[Federal Register Volume 64, Number 189 (Thursday, September 30, 1999)]
[Rules and Regulations]
[Pages 52828-53077]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 99-20430]
[[Page 52827]]
_______________________________________________________________________
Part II
Environmental Protection Agency
_______________________________________________________________________
40 CFR Part 60, et al.
NESHAPS: Final Standards for Hazardous Air Pollutants for Hazardous
Waste Combustors; Final Rule
Federal Register / Vol. 64, No. 189 / Thursday, September 30, 1999 /
Rules and Regulations
[[Page 52828]]
ENVIRONMENTAL PROTECTION AGENCY
40 CFR Parts 60, 63, 260, 261, 264, 265, 266, 270, and 271
[FRL-6413-3]
RIN 2050-AEO1
NESHAPS: Final Standards for Hazardous Air Pollutants for
Hazardous Waste Combustors
ACTION: Final rule.
-----------------------------------------------------------------------
SUMMARY: We are promulgating revised standards for hazardous waste
incinerators, hazardous waste burning cement kilns, and hazardous waste
burning lightweight aggregate kilns. These standards are being
promulgated under joint authority of the Clean Air Act (CAA) and
Resource Conservation and Recovery Act (RCRA). The standards limit
emissions of chlorinated dioxins and furans, other toxic organic
compounds, toxic metals, hydrochloric acid, chlorine gas, and
particulate matter. These standards reflect the performance of Maximum
Achievable Control Technologies (MACT) as specified by the Clean Air
Act. These MACT standards also will result in increased protection to
human health and the environment over existing RCRA standards.
DATES: This final rule is in effect on September 30, 1999. You are
required to be in compliance with these promulgated standards 3 years
following the effective date of the final rule (i.e., September 30,
2002). You are provided with the possibility of a site-specific one
year extension for the installation of controls to comply with the
final standards or for waste minimization reductions. The incorporation
by reference of certain publications listed in the rule was approved by
the Director of the Federal Register as of September 30, 1999.
ADDRESSES: The official record (i.e., public docket) for this
rulemaking is identified as Docket Numbers: F-96-RCSP-FFFFF, F-97-CS2A-
FFFFF, F-97-CS3A-FFFFF, F-97-CS4A-FFFFF, F-97-CS5A-FFFFF, F-97-CS6A-
FFFFF, F-98-RCSF-FFFFF, and F-1999-RC2F-FFFFF. The official record is
located in the RCRA Information Center (RIC), located at Crystal
Gateway One, 1235 Jefferson Davis Highway, First Floor, Arlington,
Virginia. The mailing address for the official record is RCRA
Information Center, Office of Solid Waste (5305W), U.S. Environmental
Protection Agency Headquarters, 401 M Street, SW, Washington, DC 20460.
Public comments and supporting materials are available for viewing
in the RIC. The RIC is open from 9 a.m. to 4 p.m., Monday through
Friday, excluding federal holidays. To review docket materials, you
must make an appointment by calling 703-603-9230 or by sending a
message via e-mail to: RCRA-Docket@epamail.epa.gov. You may copy a
maximum of 100 pages from any regulatory docket at no charge.
Additional copies cost 15 cent/page. The index for the official record
and some supporting materials are available electronically. See the
``Supplementary Information'' section of this Federal Register notice
for information on accessing the index and these supporting materials.
FOR FURTHER INFORMATION CONTACT: For general information, you can
contact the RCRA Hotline at 1-800-424-9346 or TDD 1-800-553-7672
(hearing impaired). In the Washington metropolitan area, call 703-412-
9810 or TDD 703-412-3323. For additional information on the Hazardous
Waste Combustion MACT rulemaking and to access available electronic
documents, please go to our Web page: www.epa.gov/hwcmact. Any
questions or comments on this rule can also be sent to EPA via our Web
page.
For more detailed information on technical requirements of this
rulemaking, you can contact Mr. David Hockey, 703-308-8846, electronic
mail: Hockey.David@epamail.epa.gov. For more detailed information on
permitting associated with this rulemaking, you can contact Ms.
Patricia Buzzell, 703-308-8632, electronic mail:
Buzzell.Tricia@epamail.epa.gov. For more detailed information on
compliance issues associated with this rulemaking, you can contact Mr.
Larry Gonzalez, 703-308-8468, electronic mail:
Gonzalez.Larry@epamail.epa.gov. For more detailed information on the
assessment of potential costs, benefits and other impacts associated
with this rulemaking, you can contact Mr. Lyn Luben, 703-308-0508,
electronic mail: Luben.Lyn@epamail.epa.gov. For more detailed
information on risk analyses associated with this rulemaking, you can
contact Mr. David Layland, 703-308-0482, electronic mail:
Layland.David@epamail.epa.gov.
SUPPLEMENTARY INFORMATION:
Official Record. The official record is the paper record maintained
at the address in ADDRESSES above. All comments that were received
electronically were converted into paper form and placed in the
official record, which also includes all comments submitted directly in
writing. Our responses to comments, whether the comments are written or
electronic, are located in the response to comments document in the
official record for this rulemaking.
Supporting Materials Availability on the Internet. The index for
the official record and the following supporting materials are
available on the Internet as:
--Technical Support Documents for HWC MACT Standards:
--Volume I: Description of Source Categories
--Volume II: HWC Emissions Database
--Volume III: Selection of MACT Standards and Technologies
--Volume IV: Compliance with the MACT Standards
--Volume V: Emission Estimates and Engineering Costs
--Assessment of the Potential Costs, Benefits and Other Impacts of the
Hazardous Waste Combustion MACT Standards--Final Rule
--Risk Assessment Support to the Development of Technical Standards for
Emissions from Combustion Units Burning Hazardous Wastes: Background
Information Document
--Response to Comments for the HWC MACT Standards Document
To access the information electronically from the World Wide Web
(WWW), type: www.epa.gov/hwcmact
Outline
Acronyms Used in the Rule
acfm--Actual cubic feet per minute
BIF--Boilers and industrial furnaces
CAA--Clean Air Act
CEMS--Continuous emissions monitors/monitoring system
CFR--Code of Federal Regulations
DOC--Documentation of Compliance
DRE--Destruction and Removal Efficiency
dscf--Dry standard cubic foot
dscm--Dry standard cubic meter
EPA/USEPA--United States Environmental Protection Agency gr--Grains
HSWA--Hazardous and Solid Waste Amendments
kg--Kilogram
MACT--Maximum Achievable Control Technology
mg--Milligrams
Mg--Megagrams (metric tons)
NOC--Notification of Compliance
NESHAP--National Emission Standards for HAPs
ng--Nanograms
NODA--Notice of Data Availability
NPRM--Notice of Proposed Rulemaking
POHC--Principal Organic Hazardous Constituent
[[Page 52829]]
ppmv--Parts per million by volume
ppmw--Parts per million by weight
RCRA--Resource Conservation and Recovery Act
R & D--Research and Development
SSRA--Site specific risk assessment
TEQ--Toxicity equivalence
g--Micrograms
Outline
Part One: Overview and Background for This Rule
I. What Is the Purpose of This Rule?
II. In Brief, What Are the Major Features of Today's Rule?
A. Which Source Categories Are Affected By This Rule?
B. How Are Area Sources Affected By This Rule?
C. What Emission Standards Are Established In This Rule?
D. What Are the Procedures for Complying with This Rule?
E. What Subsequent Performance Testing Must Be Performed?
F. What Is the Time Line for Complying with This Rule?
G. How Does This Rule Coordinate With the Existing RCRA
Regulatory Program?
III. What Is the Basis of Today's Rule?
IV. What Was the Rulemaking Process for Development of This
Rule?
Part Two: Which Devices Are Subject to Regulation?
I. Hazardous Waste Incinerators
II. Hazardous Waste Burning Cement Kilns
III. Hazardous Waste Burning Lightweight Aggregate Kilns
Part Three: How Were the National Emission Standards for Hazardous
Air Pollutants (NESHAP) in This Rule Determined?
I. What Authority Does EPA Have to Develop a NESHAP?
II. What Are the Procedures and Criteria for Development of
NESHAPs?
A. Why Are NESHAPs Needed?
B. What Is a MACT Floor?
C. How Are NESHAPs Developed?
III. How Are Area Sources and Research, Development, and
Demonstration Sources Treated in this Rule?
A. Positive Area Source Finding for Hazardous Waste Combustors
1. How Are Area Sources Treated in this Rule?
2. What Is an Area Source?
3. What Is the Basis for Today's Positive Area Source Finding?
B. How Are Research, Development, and Demonstration (RD&D)
Sources Treated in this Rule?
1. Why Does the CAA Give Special Consideration to Research and
Development (R&D) Sources?
2. When Did EPA Notice Its Intent to List R&D Facilities?
3. What Requirements Apply to Research, Development, and
Demonstration Hazardous Waste Combustor Sources?
IV. How Is RCRA's Site-Specific Risk Assessment Decision Process
Impacted by this Rule?
A. What Is the RCRA Omnibus Authority?
B. How Will the SSRA Policy Be Applied and Implemented in Light
of this Mandate?
1. Is There a Continuing Need for Site-Specific Risk
Assessments?
2. How Will the SSRA Policy Be Implemented?
C. What Is the Difference Between the RCRA SSRA Policy and the
CAA Residual Risk Requirement?
Part Four: What Is The Rationale for Today's Final Standards?
I. Emissions Data and Information Data Base
A. How Did We Develop the Data Base for this Rule?
B. How Are Data Quality and Data Handling Issues Addressed?
1. How Are Data from Sources No Longer Burning Hazardous Waste
Handled?
2. How Are Nondetect Data Handled?
3. How Are Normal Versus Worst-Case Emissions Data Handled?
4. What Approach Was Used to Fill In Missing or Unavailable
Data?
II. How Did We Select the Pollutants Regulated by This Rule?
A. Which Toxic Metals Are Regulated by This Rule?
1. Semivolatile and Low Volatile Metals
2. How Are the Five Other Metal Hazardous Air Pollutants
Regulated?
B. How Are Toxic Organic Compounds Regulated By This Rule?
1. Dioxins/Furans
2. Carbon Monoxide and Hydrocarbons
3. Destruction and Removal Efficiency
C. How Are Hydrochloric Acid and Chlorine Gas Regulated By This
Rule?
III. How Are the Standards Formatted In This Rule?
A. What Are the Units of the Standards?
B. Why Are the Standards Corrected for Oxygen and Temperature?
C. How Does the Rule Treat Significant Figures and Rounding?
IV. How Are Nondioxin/Furan Organic Hazardous Air Pollutants
Controlled?
A. What Is the Rationale for DRE as a MACT Standard?
1. MACT DRE Standard
2. How Can Previous Successful Demonstrations of DRE Be Used To
Demonstrate Compliance?
3. DRE for Sources that Feed Waste at Locations Other Than the
Flame Zone
4. Sources that Feed Dioxin Wastes
B. What Is the Rationale for Carbon Monoxide or Hydrocarbon
Standards as Surrogate Control of Organic Hazardous Air Pollutants?
V. What Methodology Is Used to Identify MACT Floors?
A. What Is the CAA Statutory Requirement to Identify MACT
Floors?
B. What Is the Final Rule Floor Methodology?
1. What Is the General Approach Used in this Final Rule?
2. What MACT Floor Approach Is Used for Each Standard?
C. What Other Floor Methodologies Were Considered?
1. April 19, 1996 Proposal
2. May 1997 NODA.
D. How Is Emissions Variability Accounted for in Development of
Standards?
1. How Is Within-Test Condition Emissions Variability Addressed?
2. How Is Waste Imprecision in the Stack Test Method Addressed?
3. How Is Source-to-Source Emissions Variability Addressed?
VI. What Are the Standards for Existing and New Incinerators?
A. To Which Incinerators Do Today's Standards Apply?
B. What Subcategorization Options Did We Evaluate?
C. What Are the Standards for New and Existing Incinerators?
1. What Are the Standards for Incinerators?
2. What Are the Standards for Dioxins and Furans?
3. What Are the Standards for Mercury?
4. What Are the Standards for Particulate Matter?
5. What Are the Standards for Semivolatile Metals?
6. What Are the Standards for Low Volatile Metals?
7. What Are the Standards for Hydrochloric Acid and Chlorine
Gas?
8. What Are the Standards for Carbon Monoxide?
9. What Are the Standards for Hydrocarbon?
10. What Are the Standards for Destruction and Removal
Efficiency?
VII. What Are the Standards for Hazardous Waste Burning Cement
Kilns?
A. To Which Cement Kilns Do Today's Standards Apply?
B. How Did EPA Initially Classify Cement Kilns?
1. What Is the Basis for a Separate Class Based on Hazardous
Waste Burning?
2. What Is the Basis for Differences in Standards for Hazardous
Waste and Nonhazardous Waste Burning Cement Kilns?
C. What Further Subcategorization Considerations Are Made?
D. What Are The Standards for Existing and New Cement Kilns?
1. What Are the Standards for Cement Kilns?
2. What Are the Dioxin and Furan Standards?
3. What Are the Mercury Standards?
4. What Are the Particulate Matter Standards?
5. What Are the Semivolatile Metals Standards?
6. What Are the Low Volatile Metals Standards?
7. What Are the Hydrochloric Acid and Chlorine Gas Standards?
8. What Are the Hydrocarbon and Carbon Monoxide Standards for
Kilns Without By-Pass Sampling Systems?
9. What Are the Carbon Monoxide and Hydrocarbon Standards for
Kilns With By-Pass Sampling Systems?
10. What Are the Destruction and Removal Efficiency Standards?
VIII. What Are the Standards for Existing and New Hazardous
Waste Burning Lightweight Aggregate Kilns?
A. To Which Lightweight Aggregate Kilns Do Today's Standards
Apply?
B. What Are the Standards for New and Existing Hazardous Waste
Burning Lightweight Aggregate Kilns?
1. What Are the Standards for Lightweight Aggregate Kilns?
[[Page 52830]]
2. What Are the Dioxin and Furan Standards?
3. What Are the Mercury Standards?
4. What Are the Particulate Matter Standards?
5. What Are the Semivolatile Metals Standards?
6. What Are the Low Volatile Metals Standards?
7. What Are the Hydrochloric Acid and Chlorine Gas Standards?
8. What Are the Hydrocarbon and Carbon Monoxide Standards?
9. What Are the Standards for Destruction and Removal
Efficiency?
Part Five: Implementation
I. How Do I Demonstrate Compliance with Today's Requirements?
A. What Sources Are Subject to Today's Rules?
1. What Is an Existing Source?
2. What Is a New Source?
B. How Do I Cease Being Subject to Today's Rule?
C. What Requirements Apply If I Temporarily Cease Burning
Hazardous Waste?
1. What Must I Do to Comply with Alternative Compliance
Requirements?
2. What Requirements Apply If I Do Not Use Alternative
Compliance Requirements?
D. What Are the Requirements for Startup, Shutdown and
Malfunction Plans?
E. What Are the Requirements for Automatic Waste Feed Cutoffs?
F. What Are the Requirements of the Excess Exceedance Report?
G. What Are the Requirements for Emergency Safety Vent Openings?
H. What Are the Requirements for Combustion System Leaks?
I. What Are the Requirements for an Operation and Maintenance
Plan?
II. What Are the Compliance Dates for this Rule?
A. How Are Compliance Dates Determined?
B. What Is the Compliance Date for Sources Affected on April 19,
1996?
C. What Is the Compliance Date for Sources That Become Affected
After April 19, 1996?
III. What Are the Requirements for the Notification of Intent to
Comply?
IV. What Are the Requirements for Documentation of Compliance?
A. What Is the Purpose of the Documentation of Compliance?
B. What Is the Rationale for the DOC?
C. What Must Be in the DOC?
V. What Are the Requirements for MACT Performance Testing?
A. What Are the Compliance Testing Requirements?
1. What Are the Testing and Notification of Compliance
Schedules?
2. What Are the Procedures for Review and Approval of Test Plans
and Requirements for Notification of Testing?
3. What Is the Provision for Time Extensions for Subsequent
Performance Tests?
4. What Are the Provisions for Waiving Operating Parameter
Limits During Subsequent Performance Tests?
B. What Is the Purpose of Comprehensive Performance Testing?
1. What Is the Rationale for the Five Year Testing Frequency?
2. What Operations Are Allowed During a Comprehensive
Performance Test?
3. What Is the Consequence of Failing a Comprehensive
Performance Test?
C. What Is the Rationale for Confirmatory Performance Testing?
1. Do the Comprehensive Testing Requirements Apply to
Confirmatory Testing?
2. What Is the Testing Frequency for Confirmatory Testing?
3. What Operations Are Allowed During Confirmatory Performance
Testing?
4. What Are the Consequences of Failing a Confirmatory
Performance Test?
D. What Is the Relationship Between the Risk Burn and
Comprehensive Performance Test?
1. Is Coordinated Testing Allowed?
2. What Is Required for Risk Burn Testing?
E. What Is a Change in Design, Operation, and Maintenance?
F. What are the Data In Lieu Allowances?
VI. What Is the Notification of Compliance?
A. What Are the Requirements for the Notification of Compliance?
B. What Is Required in the NOC?
C. What Are the Consequences of Not Submitting a NOC?
D. What Are the Consequences of an Incomplete Notification of
Compliance?
E. Is There a Finding of Compliance?
VII. What Are the Monitoring Requirements?
A. What Is the Compliance Monitoring Hierarchy?
B. How Are Comprehensive Performance Test Data Used to Establish
Operating Limits?
1. What Are the Definitions of Terms Related to Monitoring and
Averaging Periods?
2. What Is the Rationale for the Averaging Periods for the
Operating Parameter Limits?
3. How Are Performance Test Data Averaged to Calculate Operating
Parameter Limits?
4. How Are the Various Types of Operating Parameters Monitored
or Established?
5. How Are Rolling Averages Calculated Initially, Upon
Intermittent Operations, and When the Hazardous Waste Feed Is Cut
Off?
6. How Are Nondetect Performance Test Feedstream Data Handled?
C. Which Continuous Emissions Monitoring Systems Are Required in
the Rule?
1. What Are the Requirements and Deferred Actions for
Particulate Matter CEMS?
2. What Are the Test Methods, Specifications, and Procedures?
3. What Is the Status of Total Mercury CEMS?
4. What Is the Status of the Proposed Performance Specifications
for Multimetal, Hydrochloric Acid, and Chlorine Gas CEMS?
5. How Have We Addressed Other Issues: Continuous Samplers as
CEMS, Averaging Periods for CEMS, and Incentives for Using CEMS?
D. What Are the Compliance Monitoring Requirements?
1. What Are the Operating Parameter Limits for Dioxin/Furan?
2. What Are the Operating Parameter Limits for Mercury?
3. What Are the Operating Parameter Limits for Semivolatile and
Low Volatile Metals?
4. What Are the Monitoring Requirements for Carbon Monoxide and
Hydrocarbon?
5. What Are the Operating Parameter Limits for Hydrochloric
Acid/Chlorine Gas?
6. What Are the Operating Parameter Limits for Particulate
Matter?
7. What Are the Operating Parameter Limits for Destruction and
Removal Efficiency?
VIII. Which Methods Should Be Used for Manual Stack Tests and
Feedstream Sampling and Analysis?
A. Manual Stack Sampling Test Methods
B. Sampling and Analysis of Feedstreams
IX. What Are the Reporting and Recordkeeping Requirements?
A. What Are the Reporting Requirements?
B. What Are the Recordkeeping Requirements?
C. How Can You Receive Approval to Use Data Compression
Techniques?
X. What Special Provisions Are Included in Today's Rule?
A. What Are the Alternative Standards for Cement Kilns and
Lightweight Aggregate Kilns?
1. What Are the Alternative Standards When Raw Materials Cause
an Exceedance of an Emission Standard?
2. What Special Provisions Exist for an Alternative Mercury
Standard for Kilns?
B. Under What Conditions Can the Performance Testing
Requirements Be Waived?
1. How Is This Waiver Implemented?
2. How Are Detection Limits Handled Under This Provision?
C. What Other Waiver Was Proposed, But Not Adopted?
D. What Equivalency Determinations Were Considered, But Not
Adopted?
E. What are the Special Compliance Provisions and Performance
Testing Requirements for Cement Kilns with In-line Raw Mills and
Dual Stacks?
F. Is Emission Averaging Allowable for Cement Kilns with Dual
Stacks and In-line Raw Mills?
1. What Are the Emission Averaging Provisions for Cement Kilns
with In-line Raw Mills?
2. What Emission Averaging Is Allowed for Preheater or
Preheater-Precalciner Kilns with Dual Stacks?
G. What Are the Special Regulatory Provisions for Cement Kilns
and Lightweight Aggregate Kilns that Feed Hazardous Waste at a
Location Other Than the End Where Products Are Normally Discharged
and Where Fuels Are Normally Fired?
H. What is the Alternative Particulate Matter Standard for
Incinerators?
[[Page 52831]]
1. Why is this Alternative Particulate Matter Standard
Appropriate under MACT?
2. How Do I Demonstrate Eligibility for the Alternative
Standard?
3. What is the Process for the Alternative Standard Petition?
XI. What Are the Permitting Requirements for Sources Subject to
this Rule?
A. What Is the Approach to Permitting in this Rule?
1. In General What Was Proposed and What Was Commenters'
Reaction?
2. What Permitting Approach Is Adopted in Today's Rule?
3. What Considerations Were Made for Ease of Implementation?
B. What Is the Applicability of the Title V and RCRA Permitting
Requirements?
1. How Are the Title V Permitting Requirements Applicable?
2. What Is the Relationship Between the Notification of
Compliance and the Title V Permit?
3. Which RCRA Permitting Requirements Are Applicable?
4. What Is the Relationship of Permit Revisions to RCRA
Combustion Permitting Procedures?
5. What is the Relationship to the RCRA Preapplication Meeting
Requirements?
C. Is Title V Permitting Applicable to Area Sources?
D. How will Sources Transfer from RCRA to MACT Compliance and
Title V Permitting?
1. In General, How Will this Work?
2. How Will I Make the Transition to CAA Permits?
3. When Should RCRA Permits Be Modified?
4. How Should RCRA Permits Be Modified?
5. How Should Sources in the Process of Obtaining RCRA Permits
be Switched Over to Title V?
E. What is Meant by Certain Definitions?
1. Prior Approval
2. 50 Percent Benchmark
3. Facility Definition
4. No New Eligibility for Interim Status
5. What Constitutes Construction Requiring Approval?
XII. State Authorization
A. What is the Authority for Today's Rule?
B. How is the Program Delegated Under the Clean Air Act?
C. How are States Authorized Under RCRA?
Part Six: Miscellaneous Provisions and Issues
I. Does the Waiver of the Particulate Matter Standard or the
Destruction and Removal Efficiency Standard Under the Low Risk Waste
Exemption of the BIF Rule Apply?
II. What is the Status of the ``Low Risk Waste'' Exemption?
III. What Concerns Have Been Considered for Shakedown?
IV. What Are the Management Requirements Prior to Burning?
V. Are There Any Conforming Changes to Subpart X?
VI. What Are the Requirements for Bevill Residues?
A. Dioxin Testing of Bevill Residues
B. Applicability of Part 266 Appendix VIII Products of
Incomplete Combustion List
VII. Have There Been Any Changes in Reporting Requirements for
Secondary Lead Smelters?
VIII. What Are the Operator Training and Certification
Requirements?
IX. Why Did the Agency Redesignate Existing Regulations
Pertaining to the Notification of Intent to Comply and Extension of
the Compliance Date?
Part Seven: National Assessment of Exposures and Risks
I. What Changes Were Made to the Risk Methodology?
A. How Were Facilities Selected for Analysis?
B. How Were Facility Emissions Estimated?
C. What Receptor Populations Were Evaluated?
D. How Were Exposure Factors Determined?
E. How Were Risks from Mercury Evaluated?
F. How Were Risks from Dioxins Evaluated?
G. How Were Risks from Lead Evaluated?
H. What Analytical Framework Was Used to Assess Human Exposures
and Risk?
I. What Analytical Framework Was Used to Assess Ecological Risk?
II. How Were Human Health Risks Characterized?
A. What Potential Health Hazards Were Evaluated?
1. Dioxins
2. Mercury
3. Lead
4. Other Metals
5. Hydrogen Chloride
6. Chlorine
B. What are the Health Risks to Individuals Residing Near HWC
Facilities?
1. Dioxins
2. Mercury
3. Lead
4. Other Metals
5. Inhalation Carcinogens
6. Other Inhalation Exposures
C. What are the Potential Health Risks to Highly Exposed
Individuals?
1. Dioxins
2. Metals
3. Mercury
D. What is the Incidence of Adverse Health Effects in the
Population?
1. Cancer Risk in the General Population
2. Cancer Risk in the Local Population
3. Risks from Lead Emissions
4. Risks from Emissions of Particulate Matter
III. What is the Potential for Adverse Ecological Effects?
A. Dioxins
B. Mercury
Part Eight: Analytical and Regulatory Requirements
I. Executive Order 12866: Regulatory Planning and Review (58 FR
51735)
II. What Activities Have Led to Today's Rule?
A. What Analyses Were Completed for the Proposal?
1. Costs
2. Benefits
3. Other Regulatory Issues
4. Small Entity Impacts
B. What Major Comments Were Received on the Proposal RIA?
1. Public Comments
2. Peer Review
III. Why is Today's Rule Needed?
IV. What Were the Regulatory Options?
V. What Are the Potential Costs and Benefits of Today's Rule?
A. Introduction
B. Combustion Market Overview
C. Baseline Specification
D. Analytical Methodology and Findings--Engineering Compliance
Cost Analysis
E. Analytical Methodology and Findings--Social Cost Analysis
F. Analytical Methodology and Findings--Economic Impact Analysis
1. Market Exit Estimates
2. Quantity of Waste Reallocated
3. Employment Impacts
4. Combustion Price Increases
5. Industry Profits
6. National-Level Joint Economic Impacts
G. Analytical Methodology and Findings--Benefits Assessment
1. Human Health and Ecological Benefits
2. Waste Minimization Benefits
VI. What Considerations Were Given to Issues Like Equity and
Children's Health?
A. Executive Order 12898, ``Federal Actions to Address
Environmental Justice in Minority Populations and Low-Income
Populations'' (February 11, 1994)
B. Executive Order 13045: Protection of Children from
Environmental Health Risks and Safety Risks (62 FR 19885, April 23,
1997)
C. Unfunded Mandates Reform Act of 1995 (URMA) (Pub. Law 104-4)
VII. Is Today's Rule Cost Effective?
VIII. How Do the Costs of Today's Rule Compare to the Benefits?
IX. What Consideration Was Given to Small Businesses?
A. Regulatory Flexibility Act (RFA) as amended by the Small
Business Regulatory Enforcement Fairness Act of 1996 (SBREFA), 5
U.S.C. 601 et seq.
B. Analytical Methodology
C. Results--Direct Impacts
D. Results--Indirect Impacts
E. Key Assumptions and Limitations
X. Were Derived Air Quality and Non-Air Impacts Considered?
XI. The Congressional Review Act (5 U.S.C. 801 et seq., as added
by the Small Business Regulatory Enforcement Fairness Act of 1996)
XII. Paperwork Reduction Act (PRA), 5 U.S.C. 3501-3520
XIII. National Technology Transfer and Advancement Act of 1995
(Pub L. 104-113, section 12(d)) (15 U.S.C. 272 note)
XIV. Executive Order 13084: Consultation and Coordination With
Indian Tribal Governments (63 FR 27655)
Part Nine: Technical Amendments to Previous Regulations
I. Changes to the June 19, 1998 ``Fast-track'' Rule
A. Permit Streamlining Section
B. Comparable Fuels Section
[[Page 52832]]
Part One: Overview and Background for This Rule
I. What Is the Purpose of This Rule?
In this final rule, we adopt hallmark standards to more rigorously
control toxic emissions from burning hazardous waste in incinerators,
cement kilns, and lightweight aggregate kilns. These emission standards
and continuation of our RCRA risk policy create a national cap for
emissions that assures that combustion of hazardous waste in these
devices is properly controlled.
The standards themselves implement section 112 of the Clean Air Act
(CAA) and apply to the three major categories of hazardous waste
burners--incinerators, cement kilns, and lightweight aggregate kilns.
For purposes of today's rule, we refer to these three categories
collectively as hazardous waste combustors. Hazardous waste combustors
burn about 80% of the hazardous waste combusted annually within the
United States. As a result, we project that today's standards will
achieve highly significant reductions in the amount of hazardous air
pollutants being emitted each year by hazardous waste combustors. For
example, we estimate that 70 percent of the annual dioxin and furan
emissions from hazardous waste combustors will be eliminated. Mercury
emissions already controlled to some degree under existing regulations
will be further reduced by about 55 percent.
Section 112 of the CAA requires emissions standards for hazardous
air pollutants to be based on the performance of the Maximum Achievable
Control Technology (MACT). The emission standards in this final rule
are commonly referred to as MACT standards because we use the MACT
concept to determine the levels of emission control under section
112(d) of the CAA.1 At the same time, these emissions
standards satisfy our obligation under the main statute regulating
hazardous waste management, the Resource Conservation Recovery Act
(RCRA), to ensure that hazardous waste combustion is conducted in a
manner adequately protective of human health and the environment. Our
use of both authorities as the legal basis for today's rule and details
of the MACT standard-setting process are explained more fully in later
sections of this preamble. Most significantly, by using both
authorities in a harmonized fashion, we consolidate regulatory control
of hazardous waste combustion into a single set of regulations, thereby
eliminating the potential for conflicting or duplicative federal
requirements.
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\1\ The MACT standards reflect the ``maximum degree of reduction
in emissions of * * * hazardous air pollutants'' that the
Administrator determines is achievable, taking into account the cost
of achieving such emission reduction and any nonair quality health
and environmental impacts and energy requirements. Section
112(d)(2).
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Today's rule also has other important features in terms of our
legal obligations and public commitments. First, promulgation of these
standards fulfills our legal obligations under the CAA to control
emissions of hazardous air pollutants from hazardous-waste burning
incinerators and Portland cement kilns.2 Second, today's
rule fulfills our 1993 and 1994 public commitments to upgrade emission
standards for hazardous waste combustors. These commitments are the
centerpiece of our Hazardous Waste Minimization and Combustion
Strategy.3 Finally, today's rulemaking satisfies key terms
of a litigation settlement agreement entered into in 1993 with a number
of groups that had challenged our previous rule addressing emissions
from hazardous waste boilers and industrial furnaces.4
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\2\ In a 1992 Federal Register notice, we published the inital
list of categories of major and area sources of hazardous air
pollutants including hazardous waste incinerators and Portland
cement plants. See 57 FR 31576 (July 16, 1992). Today's rule meets
our obligation to issue MACT standards for hazardous waste
incinerators. Today's rule also partially meets our obligation to
issue MACT standards for Portland cement plants. To complete the
obligation, we have finalized, in a separate rulemaking, MACT
standards for the portland cement industry source category. Those
standards apply to all cement kilns except those kilns that burn
hazardous waste. See 64 FR 31898 (June 14, 1999). Those standards
also apply to other HAP emitting sources at a cement plant (such as
clinker coolers, raw mills, finish mills, and materials handling
operations) regardless of whether the plant has hazardous waste
burning cement kilns.
\3\ EPA Document Number 530-R-94-044, Office of Solid Waste and
Emergency Response, November 1994.
\4\ ``Burning of Hazardous Waste in Boilers and Industrial
Furnaces'' (56 FR 7134, February 21, 1991). These groups include the
Natural Resources Defense Council, Sierra Club, Environmental
Technology Council, National Solid Waste Management Association, and
a number of local citizens' groups.
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II. In Brief, What Are the Major Features of Today's Rule?
The major features of today's final rule are summarized below.
A. Which Source Categories Are Affected by This Rule?
This rule establishes MACT standards for three source categories,
namely: Hazardous waste burning incinerators, hazardous waste burning
cement kilns, and hazardous waste burning lightweight aggregate kilns.
As mentioned earlier, we refer to these three source categories
collectively as hazardous waste combustors.
B. How Are Area Sources Affected by This Rule?
This rule establishes that MACT standards apply to both major
sources--sources that emit or have the potential to emit 10 tons or
greater per year of any single hazardous air pollutant or 25 tons per
year or greater of hazardous air pollutants in the aggregate--and area
sources, all others. Area sources may be regulated under MACT standards
if we find that the category of area sources ``presents a threat of
adverse effects to human health or the environment * * * warranting
regulation (under the MACT standards).'' We choose to regulate area
sources in today's rule and, as a result, all hazardous waste burning
incinerators, cement kilns, and lightweight aggregate kilns will be
regulated under standards reflecting MACT.
C. What Emission Standards Are Established in This Rule?
This rule establishes emission standards for: Chlorinated dioxins
and furans; mercury; particulate matter (as a surrogate for antimony,
cobalt, manganese, nickel, and selenium); semivolatile metals (lead and
cadmium); low volatile metals (arsenic, beryllium, and chromium);
hydrogen chloride and chlorine gas (combined). This rule also
establishes standards for carbon monoxide, hydrocarbons, and
destruction and removal efficiency as surrogates in lieu of individual
standards for nondioxin/furan organic hazardous air pollutants.
D. What Are the Procedures for Complying With This Rule?
This rule establishes standards that apply at all times (including
during startup, shutdown, or malfunction), except if hazardous waste is
not being burned or is not in the combustion chamber. When not burning
hazardous waste (and when hazardous waste does not remain in the
combustion chamber), you may either follow the hazardous waste burning
standards in this rule or emission standards we promulgate, if any, for
other relevant nonhazardous waste source categories.
Initial compliance is documented by stack performance testing. To
document continued compliance with the carbon monoxide or hydrocarbon
standards, you must use continuous emissions monitoring systems. For
the remaining standards, you must document continued compliance by
monitoring limits on specified operating parameters. These operating
parameter
[[Page 52833]]
limits 5 are calculated based on performance test conditions
using specified procedures intended to ensure that the operating
conditions (and by correlation the actual emissions) do not exceed
performance test levels at any time. You must also install an automatic
waste feed cutoff system that immediately stops the flow of hazardous
waste feed to the combustor if a continuous emissions monitoring system
records a value exceeding the standard or if an operating parameter
limit is exceeded (considering the averaging period for the standard or
operating parameter). The standards and operating parameter limits
apply when hazardous waste is being fed or remains in the combustion
chamber irrespective of whether you institute the corrective measures
prescribed in the startup, shutdown, and malfunction plan.
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\5\ The term ``operating parameter limit'' and ``operating
limit'' have the same meaning and are used interchangeably in the
preamble and rule language.
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E. What Subsequent Performance Testing Must Be Performed?
You must conduct comprehensive performance testing every five
years. This testing regime is referred to as ``subsequent performance
testing.'' You must revise the operating parameter limits as necessary
based on the levels achieved during the subsequent performance test. In
addition, you must conduct confirmatory performance testing of dioxins/
furans emissions under normal operating conditions midway between
subsequent performance tests.
F. What Is the Time Line for Complying With This Rule?
The compliance date of the standards promulgated in today's rule is
three years after the date of publication of the rule in the Federal
Register, or September 30, 2002 (See CAA section 112(i)(3)(A)
indicating that the Environmental Protection Agency (EPA) may establish
a compliance date no later than three years from the date of
promulgation.) A one-year extension of the compliance date may be
requested if you cannot complete system retrofits by the compliance
date despite a good faith effort to do so.6 CAA section
112(i)(3)(B).
Continuous emissions monitoring systems and other continuous monitoring
systems for the specified operating parameters must be fully
operational by the compliance date. You must demonstrate compliance by
conducting a performance test no later than 6 months after the
compliance date (i.e., three and one-half years from the date of
publication of today's rule in the Federal Register).
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\6\ In June 1998, we promulgated a rule to allow hazardous waste
combustors also to request a one-year extension to the MACT
compliance date in cases where additional time will be needed to
install pollution prevention and waste minimization measures to
significantly reduce the amount or toxicity of hazardous waste
entering combustion feedstreams. See 63 FR at 43501 (June 19, 1998).
This provision is recodified in today's rule as 40 CFR 63.1213.
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To ensure timely compliance with the standards, by the compliance
date you must place in the operating record a Documentation of
Compliance identifying limits on the specified operating parameters you
believe are necessary and sufficient to comply with the emission
standards. These operating parameter limits (and the carbon monoxide or
hydrocarbon standards monitored with continuous monitoring systems) are
enforceable until you submit to the Administrator a Notification of
Compliance within 90 days of completion of the performance test.
The Notification of Compliance must document: (1) Compliance with
the emission standards during the performance test; (2) the revised
operating parameter limits calculated from the performance test; and
(3) conformance of the carbon monoxide or hydrocarbon continuous
emissions monitoring systems and the other continuous monitoring
systems with performance specifications. You must comply with the
revised operating parameter limits upon submittal of the Notification
of Compliance.
G. How Does This Rule Coordinate With the Existing RCRA Regulatory
Program?
You must have a RCRA permit for stack air emissions (or RCRA
interim status) until you demonstrate compliance with the MACT
standards. You do so by conducting a comprehensive performance test and
submitting a Notification of Compliance to the Administrator, as
explained above.7 Hazardous waste combustors with RCRA
permits remain subject to RCRA stack air emission permit conditions
until the RCRA permit is modified to delete those conditions. (As
discussed later in more detail, we recommend requesting modification of
the RCRA permit at the time you submit the Notification of Compliance.)
Only those provisions of the RCRA permit that are less stringent than
the MACT requirements specified in the Notification of Compliance will
be approved for deletion.8 Hazardous waste combustors still
in interim status without a full RCRA permit are no longer subject to
the RCRA stack air emissions standards for hazardous waste combustors
in Subpart O of Part 265 and subpart H of part 266 once compliance with
the MACT standards has been demonstrated and a Notification of
Compliance has been submitted to the Administrator.
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\7\ Hazardous waste combustors, of course, also continue to be
subject to applicable RCRA requirements for all other aspects of
their hazardous waste management activities that are separate from
the requirements being deferred to the CAA by this rule.
\8\ RCRA permit requirements that may be less stringent than
applicable MACT standards are nonetheless enforceable until the RCRA
permit is modified.
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You must satisfy both sets of requirements during the relatively
short period when both RCRA and MACT stack air emissions standards and
associated requirements in the RCRA permit or in RCRA interim status
regulations are effective.
You also may have existing site-specific permit conditions. On a
case-by-case basis during RCRA permit issuance or renewal, we determine
whether further regulatory control of emissions is needed to protect
human health and the environment, notwithstanding compliance with
existing regulatory standards. Additional conditions may be included in
the permit in addition to those derived from the RCRA emission
standards as necessary to ensure that facility operations are
protective of human health and the environment. Any of these risk-based
permit provisions more stringent than today's MACT standards (or that
address other emission hazards) will remain in the RCRA permit.
After the MACT compliance date, hazardous waste combustors must
continue to comply with the RCRA permit issuance process to address
nonMACT provisions (e.g., general facility standards) and potentially
conduct a risk review under Sec. 270.32(b)(2) to determine if
additional requirements pertaining to stack or other emissions are
warranted to ensure protection of human health and the environment.
III. What Is the Basis of Today's Rule?
As stated previously, this rule issues final National Emissions
Standards for Hazardous Air Pollutants (NESHAPS) under authority of
section 112 of the Clean Air Act for three source categories of
combustors: Hazardous waste burning incinerators, hazardous waste
burning cement kilns, and hazardous waste burning lightweight aggregate
kilns. The main purposes of the CAA are to protect and enhance the
quality of our Nation's
[[Page 52834]]
air resources, and to promote the public health and welfare and the
productive capacity of the population. CAA section 101(b)(1). To this
end, sections 112(a) and (d) of the CAA direct EPA to set standards for
stationary sources emitting (or having the potential to emit) ten tons
or greater of any one hazardous air pollutant or 25 tons or greater of
total hazardous air pollutants annually. Such sources are referred to
as ``major sources.''
Today's rule establishes MACT emission standards for the following
hazardous air pollutants emitted by hazardous waste burning
incinerators, hazardous waste burning cement kilns, and hazardous waste
burning lightweight aggregate kilns: Chlorinated dioxins and furans,
mercury, two semivolatile metals (lead and cadmium), three low
volatility metals (arsenic, beryllium, and chromium), and hydrochloric
acid/chlorine gas. This rule also establishes MACT control for the
other hazardous air pollutants identified in CAA section 112(b)(1)
through the adoption of standards using surrogates. For example, we
adopt a standard for particulate matter as a surrogate to control five
metals that do not have specific emission standards established in
today's rule. These five metals are antimony, cobalt, manganese,
nickel, and selenium. Also, we adopt standards for carbon monoxide,
hydrocarbons, and destruction and removal efficiency to control the
other organic hazardous air pollutants listed in section 112(b)(1) that
do not have specific emission standards established in this rule.
Today's standards meet our commitment under the Hazardous Waste
Minimization and Combustion Strategy, first announced in May 1993, to
upgrade the emission standards for hazardous waste burning facilities.
EPA's Strategy has eight goals: (1) Ensure public outreach and EPA-
State coordination; (2) pursue aggressive use of waste minimization
measures; (3) continue to ensure that combustion and alternative and
innovative technologies are safe and effective; (4) develop and impose
more rigorous controls on combustion facilities; (5) continue
aggressive compliance and enforcement efforts; (6) enhance public
involvement opportunities in the permitting process for combustion
facilities; (7) give higher priority to permitting those facilities
where a final permit decision would result in the greatest
environmental benefit or the greatest reduction in risk; and (8)
advance scientific understanding on combustion issues and risk
assessment and ensure that permits are issued in a manner that provides
proper protection of human health and the environment.
We have made significant progress in implementing the Strategy.
Today's rule meets the Strategy goal of developing and implementing
rigorous state-of-the-art safety controls on hazardous waste combustors
by using the best available technologies and the most current
science.9 We also developed a software tool (i.e., the Waste
Minimization Prioritization Tool) that allows users to access relative
persistent, bioaccumulative and toxic hazard scores for any of 2,900
chemicals that may be present in RCRA waste streams. We also committed
to the reduction of the generation of the most persistent,
bioaccumulative and toxic chemicals by 50 percent by 2005. To
facilitate this reduction we are developing a list of the persistent,
bioaccumulative and toxic chemicals of greatest concern and a plan for
working with the regulated community to reduce these chemicals. In
addition, we promulgated new requirements to enhance public involvement
in the permitting process 10 and performed risk evaluations
during the permitting process for high priority facilities. We also
made allowances for one-year extensions to the MACT compliance period
as incentives designed to promote the installation of cost-effective
pollution prevention technologies to replace or supplement emission
control technologies for meeting MACT standards.
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\9\ The three source categories covered by today's final rule
burn more than 80 percent of the total amount of hazardous waste
being combusted each year. The remaining 15-20 percent is burned in
industrial boilers and other types of industrial furnaces, which
will be addressed in a future NESHAPS rulemaking for hazardous waste
burning sources.
\10\ See 60 FR 63417 (December 11, 1995).
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Finally, with regard to the regulatory framework that will result
from today's rule, we are eliminating the existing RCRA stack emissions
national standards for hazardous waste incinerators, cement kilns, and
lightweight aggregate kilns. That is, after submittal of the
Notification of Compliance established by today's rule (and, where
applicable, RCRA permit modifications at individual facilities), RCRA
national stack emission standards will no longer apply to these
hazardous waste combustors. We originally issued air emission standards
under the authority of section 3004(a) of RCRA, which calls for EPA to
promulgate standards ``as may be necessary to protect human health and
the environment.'' In light of today's new MACT standards, we have
determined that RCRA emissions standards for these sources would only
be duplicative and so are no longer necessary to protect human health
and the environment. Under the authority of section 3004(a), it is
appropriate to eliminate such duplicative standards.
Emission standards for hazardous waste burning incinerators and
other sources burning hazardous wastes as fuel must be protective of
human health and the environment under RCRA. We conducted a
multipathway risk assessment to assess the ecological and human health
risks that are projected to occur under the MACT standards. We have
concluded that the MACT standards are generally protective of human
health and the environment and that separate RCRA emission standards
are not needed. Please see a full discussion of the national assessment
of exposures and risk in Part VIII of this preamble.
Additionally, RCRA section 1006(b) directs EPA to integrate the
provisions of RCRA for purposes of administration and enforcement and
to avoid duplication, to the maximum extent practicable, with the
appropriate provisions of the Clean Air Act and other federal statutes.
This integration must be done in a way that is consistent with the
goals and policies of these statutes. Therefore, section 1006(b)
provides further authority for EPA to eliminate the existing RCRA stack
emissions standards to avoid duplication with the new MACT standards.
Nevertheless, under the authority of RCRA's ``omnibus'' clause (section
3005(c)(3); see 40 CFR 270.32(b)(2)), RCRA permit writers may still
impose additional terms and conditions on a site-specific basis as may
be necessary to protect human health and the environment.
IV. What Was the Rulemaking Process for Development of This Rule?
We proposed MACT standards for hazardous waste burning
incinerators, hazardous waste burning cement kilns, and hazardous waste
burning lightweight aggregate kilns on April 19, 1996. (61 FR 17358) In
addition, we published five notices of data availability (NODAs):
1. August 23, 1996 (61 FR 43501), inviting comment on information
pertaining to a peer review of three aspects of the proposed rule and
information pertaining to the since-promulgated ``Comparable Fuels''
rule (see 63 FR 43501 (June 19, 1998));
2. January 7, 1997 (62 FR 960), inviting comment on an updated
hazardous waste combustor data base containing the emissions and
ancillary
[[Page 52835]]
data that the Agency used to develop the final rule;
3. March 21, 1997 (62 FR 13775), inviting comment on our approach
to demonstrate the technical feasibility of monitoring particulate
matter emissions from hazardous waste combustors using continuous
emissions monitoring systems;
4. May 2, 1997 (62 FR 24212), inviting comment on several topics
including the status of establishing MACT standards for hazardous waste
combustors using a revised emissions data base and the status of
various implementation issues, including compliance dates, compliance
requirements, performance testing, and notification and reporting
requirements; and
5. December 30, 1997 (62 FR 67788), inviting comment on several
status reports pertaining to particulate matter continuous emissions
monitoring systems.
Finally, we have had many formal and informal meetings with
stakeholders, representing an on-going dialogue on various aspects of
the rulemaking.
We carefully considered information and comments submitted by
stakeholders on these rulemaking actions and during meetings. We
address their comments in our Response to Comments documents, which can
be found in the public docket supporting this rulemaking. In addition,
we addressed certain significant comments at appropriate places in this
preamble.
Part Two: Which Devices Are Subject to Regulation?
I. Hazardous Waste Incinerators
Hazardous waste incinerators are enclosed, controlled flame
combustion devices, as defined in 40 CFR 260.10. These devices may be
fixed or transportable. Major incinerator designs used in the United
States are rotary kilns, fluidized beds, liquid injection and fixed
hearth, while newer designs and technologies are also coming into
operation. Detailed descriptions of the designs, types of facilities
and typical air pollution control devices were presented in the April
1996 NPRM and in the technical background document prepared to support
the NPRM. (See 61 FR 17361, April 19, 1996.) In 1997, there were 149
hazardous waste incinerator facilities operating 189 individual units
in the U.S. Of these 149 facilities, 20 facilities (26 units) were
commercial hazardous waste incinerators, while the remaining 129
facilities (163 units) were on-site hazardous waste incinerators.
II. Hazardous Waste Burning Cement Kilns
Cement kilns are horizontally inclined rotating cylinders, lined
with refractory-brick, and internally fired. Cement kilns are designed
to calcine, or drive carbon dioxide out of, a blend of raw materials
such as limestone, shale, clay, or sand to produce Portland cement.
When combined with sand, gravel, water, and other materials, Portland
cement forms concrete, a material used widely in many building and
construction applications.
Generally, there are two different processes used to produce
Portland cement: a wet process and a dry process. In the wet process,
raw materials are ground, wetted, and fed into the kiln as a slurry. In
the dry process, raw materials are ground and fed dry into the kiln.
Wet process kilns are typically longer in length than dry process kilns
to facilitate water evaporation from the slurried raw material. Dry
kilns use less energy (heat) and also can use preheaters or
precalciners to begin the calcining process before the raw materials
are fed into the kiln.
A number of cement kilns burn hazardous waste-derived fuels to
replace some or all of normal fossil fuels such as coal. Most kilns
burn liquid waste; however, cement kilns also may burn bulk solids and
small containers containing viscous or solid hazardous waste fuels.
Containers are introduced either at the upper, raw material end of the
kiln or at the midpoint of the kiln.
All existing hazardous waste burning cement kilns use particulate
matter control devices. These cement plants either use fabric filters
(baghouses) or electrostatic precipitators to control particulate
matter.
In 1997, there were 18 Portland cement plants operating 38
hazardous waste burning kilns. Of these 38 kilns, 27 kilns use the wet
process to manufacture cement and 11 kilns use the dry process. Of the
dry process kilns, one kiln uses a preheater and another kiln used a
preheater and precalciner. Detailed descriptions of the design types of
facilities and typical air pollution control devices are presented in
the technical background document.\11\
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\11\ USEPA, ``Final Technical Support Document for HWC MACT
Standards, Volume I: Description of Source Categories,'' July 1999.
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In developing standards, the Agency considered the appropriateness
of distinguishing among the different types of cement kilns burning
hazardous waste. We determined that distinguishing subcategories of
hazardous waste burning cement kilns was not needed to develop uniform,
achievable MACT standards. (See Part Four, Section VII of the preamble
for a discussion of subcategory considerations.)
III. Hazardous Waste Burning Lightweight Aggregate Kilns
The term ``lightweight aggregate'' refers to a wide variety of raw
materials (such as clay, shale, or slate) that, after thermal
processing, can be combined with cement to form concrete products.
Lightweight aggregate concrete is produced either for structural
purposes or for thermal insulation purposes. A lightweight aggregate
plant is typically composed of a quarry, a raw material preparation
area, a kiln, a cooler, and a product storage area. The material is
taken from the quarry to the raw material preparation area and from
there is fed into the rotary kiln.
A rotary kiln consists of a long steel cylinder, lined internally
with refractory bricks, which is capable of rotating about its axis and
is inclined horizontally. The prepared raw material is fed into the
kiln at the higher end, while firing takes place at the lower end. As
the raw material is heated, it melts into a semiplastic state and
begins to generate gases that serve as the bloating or expanding agent.
As temperatures reach their maximum, the semiplastic raw material
becomes viscous and entraps the expanding gases. This bloating action
produces small, unconnected gas cells, which remain in the material
after it cools and solidifies. The product exits the kiln and enters a
section of the process where it is cooled with cold air and then
conveyed to the discharge. Kiln operating parameters such as flame
temperature, excess air, feed size, material flow, and speed of
rotation vary from plant to plant and are determined by the
characteristics of the raw material.
In 1997, there were five lightweight aggregate kiln facilities in
the United States operating 10 hazardous waste-fired kilns. Detailed
descriptions of the lightweight aggregate process and air pollution
control techniques are presented in the technical support document.\12\
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\12\ USEPA, ``Final Technical Support Document for HWC MACT
Standards, Volume I: Description of Source Categories,'' July 1999.
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[[Page 52836]]
Part Three: How Were the National Emission Standards for Hazardous
Air Pollutants (NESHAP) in This Rule Determined?
I. What Authority Does EPA Have To Develop a NESHAP?
The 1990 Amendments to the Clean Air Act (CAA) significantly
revised the requirements for controlling emissions of hazardous air
pollutants. EPA is required to develop a list of categories of major
and area sources of the hazardous air pollutants identified in section
112 and to develop, over specified time periods, technology-based
performance standards for sources of these hazardous air pollutants.
See CAA sections 112(c) and 112(d). These source categories and
subcategories are to be listed pursuant to section 112(c)(1). We
published an initial list of 174 categories of such major and area
sources in the Federal Register on July 16, 1992 (57 FR 31576), which
was later amended at 61 FR 28197 (June 4, 1996) \13\ and 63 FR 7155
(February 12, 1998). That list includes the Hazardous Waste
Incineration, Portland Cement Manufacturing, and Clay Products
Manufacturing source categories.
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\13\ A subsequent Notice was published on July 18, 1996 (61 FR
37542) which corrected typographical errors in the June 4, 1996
Notice.
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Promulgation of technology-based standards for these listed source
categories is not necessarily the final step in the process. CAA
section 112(f) requires the Agency to report to Congress on the
estimated risk remaining after imposition of technology-based standards
and make recommendations as to additional legislation needed to address
such risk. If Congress does not act on any recommendation presented in
this report, we are required to impose additional controls if such
controls are needed to protect public health with an ample margin of
safety or (taking into account costs, energy, safety, and other
relevant factors) to prevent adverse environmental effects. In
addition, if the technology-based standards for carcinogens do not
reduce the lifetime excess cancer risk for the most exposed individual
to less than one in a million (1 x 10-6), then we must
promulgate additional standards.
We prepared the Draft Residual Risk Report to Congress and
announced its release on April 22, 1998 (63 FR 19914-19916). In that
report, we did not propose any legislative recommendation to Congress.
In section 4.2.4 of the report, we state that: ``The legislative
strategy embodied in the 1990 CAA Amendments adequately maintains the
goal of protecting the public health and the environment and provides a
complete strategy for dealing with a variety of risk problems. The
strategy recognizes that not all problems are national problems or have
a single solution. National emission standards will be promulgated to
decrease the emissions of as many hazardous air pollutants as possible
from major sources.''
II. What Are the Procedures and Criteria for Development of NESHAPs?
A. Why Are NESHAPs Needed?
NESHAPs are developed to control hazardous air pollutant emissions
from both new and existing sources. The statute requires a NESHAP to
reflect the maximum degree of reduction of hazardous air pollutant
emissions that is achievable taking into consideration the cost of
achieving the emission reduction, any nonair quality health and
environmental impacts, and energy requirements. NESHAPs are often
referred to as maximum achievable control technology (or MACT)
standards.
We are required to develop MACT emission standards based on
performance of the best control technologies for categories or sub-
categories of major sources of hazardous air pollutants. We also can
establish lower thresholds for determining which sources are major
where appropriate. In addition, we may require sources emitting
particularly dangerous hazardous air pollutants such as particular
dioxins and furans to control those pollutants under the MACT standards
for major sources.
In addition, we regulate area sources by technology-based standards
if we find that these sources (individually or in the aggregate)
present a threat of adverse effects to human health or the environment
warranting regulation. After such a determination, we have a further
choice whether to require technology-based standards based on MACT or
on generally achievable control technology.
B. What Is a MACT Floor?
The CAA directs EPA to establish minimum emission standards,
usually referred to as MACT floors. For existing sources in a category
or subcategory with 30 or more sources, the MACT floor cannot be less
stringent than the ``average emission limitation achieved by the best
performing 12 percent of the existing sources. * * *'' For existing
sources in a category or subcategory with less than 30 sources, the
MACT floor cannot be less stringent than the ``average emission
limitation achieved by the best performing 5 sources. * * *'' For new
sources, the MACT floor cannot be ``less stringent than the emission
control that is achieved by the best controlled similar source. * * *''
We must consider in a NESHAP rulemaking whether to develop
standards that are more stringent than the floor, which are referred to
as ``beyond-the-floor'' standards. To do so, we must consider statutory
criteria, such as the cost of achieving emission reduction, cost
effectiveness, energy requirements, and nonair environmental
implications.
Section 112(d)(2) specifies that emission reductions may be
accomplished through the application of measures, processes, methods,
systems, or techniques, including, but not limited to: (1) Reducing the
volume of, or eliminating emissions of, such pollutants through process
changes, substitution of materials, or other modifications; (2)
enclosing systems or processes to eliminate emissions; (3) collecting,
capturing, or treating such pollutants when released from a process,
stack, storage, or fugitive emissions point; (4) design, equipment,
work practice, or operational standards (including requirements for
operator training or certification); or (5) any combination of the
above. See section 112(d)(2).
Application of techniques (1) and (2) are consistent with the
definitions of pollution prevention under the Pollution Prevention Act
and the definition of waste minimization under RCRA. In addition, these
definitions are in harmony with our Hazardous Waste Minimization and
Combustion Strategy. These terms have particular applicability in the
discussion of pollution prevention/waste minimization incentives, which
were finalized at 63 FR 33782 (June 19, 1998) and which are summarized
in the permitting and compliance sections of this final rule.
C. How Are NESHAPs Developed?
To develop a NESHAP, we compile available information and in some
cases collect additional information about the industry, including
information on emission source quantities, types and characteristics of
hazardous air pollutants, pollution control technologies, data from
emissions tests (e.g., compliance tests, trial burn tests) at
controlled and uncontrolled facilities, and information on the costs
and other energy and environmental impacts of emission control
techniques. We use this information in analyzing and developing
possible regulatory
[[Page 52837]]
approaches. Of course, we are not always able to assemble the same
amount of information per industry and typically base the NESHAP on
information practically available.
NESHAPs are normally structured in terms of numerical emission
limits. However, alternative approaches are sometimes necessary and
appropriate. Section 112(h) authorizes the Administrator to promulgate
a design, equipment, work practice, or operational standard, or a
standard that is a combination of these alternatives.
III. How Are Area Sources and Research, Development, and Demonstration
Sources Treated in This Rule?
A. Positive Area Source Finding for Hazardous Waste Combustors
1. How Are Area Sources Treated in This Rule?
In today's final rule, we make a positive area source finding
pursuant to CAA section 112(c)(3) for hazardous waste burning
incinerators, hazardous waste burning cement kilns, and hazardous waste
burning lightweight aggregate kilns. This rule subjects both major and
area sources in these three source categories to the same standards--
the section 112(d) MACT standards. We make this positive area source
determination because emissions from area sources subject to today's
rule present a threat of adverse effects to human health and the
environment. These threats warrant regulation under the section 112
MACT standards.
2. What Is an Area Source?
Area sources are sources emitting (or having the potential to emit)
less than 10 tons per year of an individual hazardous air pollutant,
and less than 25 tons per year of hazardous air pollutants in the
aggregate. These sources may be regulated under MACT standards if we
find that the sources ``presen[t] a threat of adverse effects to human
health or the environment (by such sources individually or in the
aggregate) warranting regulation under this section.'' Section
112(c)(3).
As part of our analysis, we estimate that all hazardous waste
burning lightweight aggregate kilns are major sources, principally due
to their hydrochloric acid emissions. We also estimate that
approximately 80 percent of hazardous waste burning cement kilns are
major sources, again due to hydrochloric acid emissions. Only
approximately 30 percent of hazardous waste burning incinerators appear
to be major sources, considering only the stack emissions from the
incinerator. However, major and area source status is determined by the
entire facility's hazardous air pollutant emissions, so that many on-
site hazardous waste incinerators are major sources because they are
but one contributing source of emissions among others (sometimes many
others at large manufacturing complexes) at the same facility.
3. What Is the Basis for Today's Positive Area Source Finding?
The consequences of us not making a positive area source finding in
this rule would result in an undesirable bifurcated regulation. First,
the CAA provides independent authority to regulate certain hazardous
air pollutant emissions under MACT standards, even if the emissions are
from area sources. These are the hazardous air pollutants enumerated in
section 112(c)(6), and include 2,3,7,8 dichlorobenzo-p-dioxins and
furans, mercury, and some specific polycyclic organic hazardous air
pollutants--hazardous air pollutants regulated under this rule. See 62
FR at 24213-24214. Thus, all sources covered by today's rule would have
to control these hazardous air pollutants to MACT levels, even if we
were not to make a positive area source determination. Second, because
all hazardous air pollutants are fully regulated under RCRA, area
source hazardous waste combustors would have not only a full RCRA
permit, but also (as just explained) a CAA title V permit for the
section 112(c)(6) hazardous air pollutants. One purpose of this rule is
to avoid the administrative burden to sources resulting from this type
of dual permitting, and these burdensome consequences of not making a
positive area source finding have influenced our decision that area
source hazardous waste combustors ``warrant regulation'' under section
112(d)(2).
a. Health and Environmental Factors. Our positive area source
finding is based on the threats presented by emissions of hazardous air
pollutants from area sources. We find that these threats warrant
regulation under the MACT standards given the evident Congressional
intent for uniform regulation of hazardous waste combustion sources, as
well as the common emission characteristics of these sources and
amenability to the same emission control mechanisms.
As discussed in both the April 1996 proposal and May 1997 NODA, all
hazardous waste combustion sources, including those that may be area
sources, have the potential to pose a threat of adverse effects to
human health or the environment, although some commenters disagree with
this point. These sources emit some of the most toxic, bioaccumulative
and persistent hazardous air pollutants--among them dioxins, furans,
mercury, and organic hazardous air pollutants. As discussed in these
Federal Register notices and elsewhere in today's final rule, potential
hazardous waste combustor area sources can be significant contributors
to national emissions of these hazardous air pollutants. (See 62 FR
17365 and 62 FR 24213.)
Our positive area source finding also is based on the threat posed
by products of incomplete combustion. The risks posed by these
hazardous air pollutants cannot be directly quantified on a national
basis, because each unit emits different products of incomplete
combustion in different concentrations. However, among the products of
incomplete combustion emitted from these sources are potential
carcinogens.\14\ The potential threat posed by emissions of these
hazardous air pollutants is manifest and, for several reasons, we do
not believe that control of these products of incomplete combustion
should be left to the RCRA omnibus permitting process. First, we are
minimizing the administrative burden on sources from duplicative
permitting in this rule by minimizing the extent of RCRA permitting and
hence minimizing our reliance on the omnibus process. Second, we are
dealing with hazardous air pollutant emissions from these sources on a
national rather than a case-by-case basis. We conclude that the control
of products of incomplete combustion from all hazardous waste
combustors through state-of-the art organic pollution control is the
best way to do so from an implementation standpoint. Finally, a basic
premise of the CAA is that there are so many uncertainties and
difficulties in developing effective risk-based regulation of hazardous
air pollutants that the first step should be technology-based standards
based on Maximum Available Control Technology. See generally S. Rep.
No. 228, 101st Cong. 1st Sess. 128-32 (1990). The positive area source
finding and consequent MACT controls is consistent with this primary
legislative objective.
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\14\ E.g., benzene, methylene chloride, hexachlorobenzene,
carbon tetrachloride, vinal chloride, benzo(a)pyrene, and
chlorinated dioxins and furans. Energy and Environmental Research
Corp., surrogate Evaluation for Thermal Treatment Systems, Draft
Report, October 1994. Also see: USEPA, ``Final technical Support
Document for HWC MACT Standards, Volume III: Section of MACT
Standards and Technologies,'' July 1999.
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The quantitative risk assessment for the final rule did not find
risk from
[[Page 52838]]
mercury emissions from hazardous waste burning area source cement kilns
to be above levels we generally consider acceptable. However, the
uncertainties underlying the analysis are such that only qualitative
judgments can be made. We do not believe our analysis can be relied
upon to make a definitive quantitative finding about the precise
magnitude of the risk. See Part Five, Section XIII for a discussion of
uncertainty. Background exposures, which can be quite variable, were
not considered in the quantitative assessment and are likely to
increase the risk from incremental exposures to mercury from area
source cement kilns. Commenters, on the other hand, believed that
cement kilns did not pose significant risk and questioned our risk
estimates made in the April 1996 NPRM and May 1997 NODA. However,
taking into account the uncertainty of our mercury analysis and the
likelihood of background exposures, a potential for risk from mercury
may exist. Furthermore, the information available concerning the
adverse human health effects of mercury, along with the magnitude of
the emissions of mercury from area source cement kilns, also indicate
that a threat of adverse effects is presumptive and that a positive
area source finding is warranted.
b. Other Reasons Warranting Regulation under Section 112. Other
special factors indicate that MACT standards are warranted for these
sources.
The first reason is Congress's, our, and the public's strong
preference for similar, if not identical, regulation of all hazardous
waste combustors. Area sources are currently regulated uniformly under
RCRA, with no distinction being made between smaller and larger
emitters. This same desire for uniformity is reflected in the CAA. CAA
section 112(n)(7) directs the Agency, in its regulation of HWCs under
RCRA, to ``take into account any regulations of such emissions which
are promulgated under such subtitle (i.e., RCRA) and shall, to the
maximum extent practicable and consistent with the provisions of this
section, ensure that the requirements of such subtitle and this section
are consistent.'' Congress also dealt with these sources as a single
class by excluding hazardous waste combustion units regulated by RCRA
permits from regulation as municipal waste combustors under CAA section
129(g)(1). Thus, a strong framework in both statutes indicates that air
emissions from all hazardous waste combustors should be regulated under
a uniform approach. Failure to adopt such a uniform approach would
therefore be inconsistent with Congressional intent as expressed in
both the language and the structure of RCRA and the CAA. Although many
disagree, several commenters support the approach to apply uniform
regulations for all hazardous waste combustors and assert that it is
therefore appropriate and necessary to make the positive area source
finding.
Second, a significant number of hazardous waste combustors could
plausibly qualify as area sources by the compliance date through
emissions reductions of one or more less dangerous hazardous air
pollutants, such as total chlorine. We conclude it would be
inappropriate to exclude from CAA 112(d) regulation and title V
permitting a significant portion of the sources contributing to
hazardous air pollutant emissions, particularly nondioxin products of
incomplete combustion should this occur.
Third, the MACT controls identified for major sources are
reasonable and appropriate for potential area sources. The emissions
control equipment (and where applicable, feedrate control) defined as
floor or beyond-the-floor control for each source category is
appropriate and can be installed and operated at potential area
sources. There is nothing unique about the types and concentrations of
emissions of hazardous air pollutants from any class of hazardous waste
combustors that would make MACT controls inappropriate for that
particular class of hazardous waste combustors, but not the others.
Commenters also raised the issue of applying generally available
control technologies (GACT), in lieu of MACT, to area sources.
Consideration of GACT lead us to the conclusion that GACT would likely
involve the same types and levels of control as we identified for MACT.
We believe GACT would be the same as MACT because the standards of this
rule, based on MACT, are readily achievable, and therefore would also
be determined to be generally achievable, i.e., GACT.
Finally, we note that the determination here is unique to these
RCRA sources, and should not be viewed as precedential for other CAA
sources. In the language of the statute, there are special reasons that
these RCRA sources warrant regulation under section 112(d)(2)--and so
warrant a positive area source finding--that are not present for usual
CAA sources. These reasons are discussed above--the Congressional
desire for uniform regulation and our desire (consistent with this
Congressional objective) to avoid duplicative permitting of these
sources wherever possible. We repeat, however, that the positive area
source determination here is not meant as a precedent outside the dual
RCRA/CAA context.
B. How Are Research, Development, and Demonstration (RD&D) Sources
Treated in This Rule?
Today's rule excludes research, development, and demonstration
sources from the hazardous waste burning incinerator, cement kiln, and
lightweight aggregate kiln source categories. We discuss below the
statutory mandate to give special consideration to research and
development (R&D) sources, an Advanced Notice of Proposed Rulemaking to
list R&D facilities that we published in 1997, and qualifications for
exclusion of R&D sources from the hazardous waste combustor source
categories.
1. Why Does the CAA Give Special Consideration to Research and
Development (R&D) Sources?
Section 112(c)(7) of the Clean Air Act requires EPA to ``establish
a separate category covering research or laboratory facilities, as
necessary to assure the equitable treatment of such facilities.''
Congress included such language in the Act because it was concerned
that research and laboratory facilities should not arbitrarily be
included in regulations that cover manufacturing operations. The Act
defines a research or laboratory facility as ``any stationary source
whose primary purpose is to conduct research and development into new
processes and products, where such source is operated under the close
supervision of technically trained personnel and is not engaged in the
manufacture of products for commercial sale in commerce, except in a de
minimis manner.''
We interpret the Act as requiring the listing of R&D major sources
as a separate category to ensure equitable treatment of such
facilities. Language in the Act specifying special treatment of R&D
facilities (section 112(c)(7)), along with language in the legislative
history of the Act, suggests that Congress considered it inequitable to
subject the R&D facilities of an industry to a standard designed for
the commercial production processes of that industry. The application
of such a standard may be inappropriate because the wide range of
operations and sizes of R&D facilities. Further, the frequent changes
in R&D operations may be significantly different from the typically
large and continuous production processes.
We have no information indicating that there are R&D sources, major
or
[[Page 52839]]
area, that are required to be listed and regulated, other than those
associated with sources already included in listed source categories
listed today. Although we are not aware of other R&D sources that need
to be added to the source category list, such sources may exist, and we
requested information about them in an Advance Notice of Proposed
Rulemaking, as discussed in the next section.
2. When Did EPA Notice Its Intent To List R&D Facilities?
In May 1997 (62 FR 25877), we provided advanced notice that we were
considering whether to list R&D facilities. We requested public
comments and information on the best way to list and regulate such
sources. Comment letters were received from industry, academic
representatives, and governmental entities. After we compile additional
data, we will respond to these comments in that separate docket. As a
result we are not deciding how to address the issue in today's rule.
The summary of comments and responses will be one part of the basis for
our future decision whether to list R&D facilities as a source category
of hazardous air pollutants.
3. What Requirements Apply to Research, Development, and Demonstration
Hazardous Waste Combustor Sources?
This rule excludes research, development, and demonstration sources
from the hazardous waste incinerator, cement kiln, or lightweight
aggregate kiln source categories and therefore from compliance with
today's regulations. We are excluding research, development, and
demonstration sources from those source categories because the emission
standards and compliance assurance requirements for those source
categories may not be appropriate. The operations and size of a
research, development, and demonstration source may be significantly
different from the typical hazardous waste incinerator that is
providing ongoing waste treatment service or hazardous waste cement
kiln or hazardous waste lightweight aggregate kiln that is producing a
commercial product as well as providing ongoing waste treatment.
We also are applying the exclusion to demonstration sources because
demonstration sources are operated more like research and development
sources than production sources. Thus, the standards and requirements
finalized today for production sources may not be appropriate for
demonstration sources. Including demonstration sources in the exclusion
is consistent with our current regulations for hazardous waste
management facilities. See Sec. 270.65 providing opportunity for
special operating permits for research, development, and demonstration
sources that use an innovative and experimental hazardous waste
treatment technology or process.
To ensure that research, development, and demonstration sources are
distinguished from production sources, we have drawn from the language
in section 112(c)(7) to define a research, development, and
demonstration source. Specifically, these are sources engaged in
laboratory, pilot plant, or prototype demonstration operations: (1)
Whose primary purpose is to conduct research, development, or short-
term demonstration of an innovative and experimental hazardous waste
treatment technology or process; and (2) where the operations are under
the close supervision of technically-trained personnel.15
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\15\The statute also qualifies that research and development
sources do not engage in the manufacture of products for commercial
sale except in a de minimis manner. Although this qualification is
appropriate for research and development sources, engaged in short-
term demonstration of an innovative or experimental treatment
technology or process may produce products for use in commerce. For
example, a cement kiln engaged in a short-term demonstration of an
innovative process may nonetheless produce marketable clinker in
other than de minimis quantities. Consequently, we are not including
this qualification in the definition of a research, development, and
demonstration source.
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In addition, today's rule limits the exclusion to research,
development, and demonstration sources that operate for not longer than
one year after first processing hazardous waste, unless the
Administrator grants a time extension based on documentation that
additional time is needed to perform research development, and
demonstration operations. We believe that this time restriction will
help distinguish between research, development, and demonstration
sources and production sources. This time restriction draws from the
one-year time restriction (unless extended on a case-by-case basis)
currently applicable to hazardous waste research, development, and
demonstration sources under Sec. 270.65.
The exclusion of research, development, and demonstration sources
applies regardless of whether the sources are located at the same site
as a production hazardous waste combustor that is subject to the MACT
standards finalized today. A research, development, and demonstration
source that is co-located at a site with a production source still
qualifies for the exclusion. A research, development, and demonstration
source co-located with a production source is nonetheless expected to
experience the type and range of operations and be of the size typical
for other research, development, and demonstration sources.
Finally, hazardous waste research, development, and demonstration
sources remain subject to RCRA permit requirements under Sec. 270.65,
which direct the Administrator to establish permit terms and conditions
that will assure protection of human health and the environment.
Although we did not propose this exclusion specifically for
hazardous waste combustor research, development, and demonstration
sources, the exclusion is an outgrowth of the May 1997 notice discussed
above. In that notice we explain that we interpret the CAA as requiring
the listing of research and development major sources as a separate
category to ensure equitable treatment of such facilities. A commenter
on the April 1996 hazardous waste combustor NPRM questioned whether we
intended to apply the proposed regulations to research and development
sources. We did not have that intent, and in response are finalizing
today an exclusion of research, development, and demonstration sources
from the hazardous waste incinerator, hazardous waste burning cement
kiln, and hazardous waste burning lightweight aggregate kiln source
categories.
IV. How Is RCRA's Site-Specific Risk Assessment Decision Process
Impacted by This Rule?
RCRA Sections 3004(a) and (q) mandate that standards governing the
operation of hazardous waste combustion facilities be protective of
human health and the environment. To meet this mandate, we developed
national combustion standards under RCRA, taking into account the
potential risk posed by direct inhalation of the emissions from these
sources.16 With advancements in the assessment of risk since
promulgation of the original national standards (i.e., 1981 for
incinerators and 1991 for boilers and industrial furnaces), we
recognized in the 1993 Hazardous Waste Minimization and Combustion
Strategy that additional risk analysis was appropriate. Specifically,
we noted that the risk posed by indirect exposure (e.g., ingestion of
contamination in the food chain) to long-term deposition of metals,
[[Page 52840]]
dioxin/furans and other organic compounds onto soils and surface waters
should be assessed in addition to the risk posed by direct inhalation
exposure to these contaminants. We also recognized that the national
assessments performed in support of the original hazardous waste
combustor standards did not take into account unique and site-specific
considerations which might influence the risk posed by a particular
source. Therefore, to ensure the RCRA mandate was met on a facility-
specific level for all hazardous waste combustors, we strongly
recommended in the Strategy that site-specific risk assessments
(SSRAs), including evaluations of risk resulting from both direct and
indirect exposure pathways, be conducted as part of the RCRA permitting
process. In those situations where the results of a SSRA showed that a
facility's operations could pose an unacceptable risk (even after
compliance with the RCRA national regulatory standards), additional
risk-based, site-specific permit conditions could be imposed pursuant
to RCRA's omnibus authority (section 3005(c)(3)).
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\16\ See No CFR part 264, subpart O for incinerator standards
and 40 CFR part 266, subpart H for BIF standards.
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Today's MACT standards were developed pursuant to section 112(d) of
the CAA, which does not require a concurrent risk evaluation of those
standards. To determine if the MACT standards would satisfy the RCRA
protectiveness mandate in addition to the requirements of the CAA, we
conducted a national RCRA evaluation of both direct and indirect risk
as part of this rulemaking. If we found the MACT standards to be
sufficiently protective so as to meet the RCRA mandate as well, we
could consider modifying our general recommendation that SSRAs be
conducted for all hazardous waste combustors, thereby lessening the
regulatory burden to both permitting authorities and facilities.
In this section, we discuss: The applicability of both the RCRA
omnibus authority and the SSRA policy to hazardous waste combustors
subject to today's rulemaking; the implementation of the SSRA policy;
the relationship of the SSRA policy to the residual risk requirement of
section 112(f) of the CAA; and public comments received on these
topics. A discussion of the national risk characterization methodology
and results is provided in Part Five, Section XIII of today's notice.
A. What Is the RCRA Omnibus Authority?
Section 3005(c)(3) of RCRA (codified at 40 CFR 270.32(b)(2))
requires that each hazardous waste facility permit contain the terms
and conditions necessary to protect human health and the environment.
This provision is commonly referred to as the ``omnibus authority'' or
``omnibus provision.'' It is the means by which additional site-
specific permit conditions may be incorporated into RCRA permits should
such conditions be necessary to protect human health and the
environment.17 SSRAs have come to be used by permitting
authorities as a quantitative basis for making omnibus determinations
for hazardous waste combustors.
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\17\ The risk-based permit conditions are in addition to those
conditions required by the RCRA national regulatory standards for
hazardous waste combustors (e.g., general facility requirements).
---------------------------------------------------------------------------
In the April 1996 NPRM and May 1997 NODA, we discussed the RCRA
omnibus provision and its relation to the new MACT standards.
Commenters question whether the MACT standards supersede the omnibus
authority with respect to hazardous waste combustor air emissions.
Other commenters agree in principle with the continued applicability of
the omnibus authority after promulgation of the MACT standards. These
commenters recognize that there may be unique conditions at a given
site that may warrant additional controls to those specified in today's
notice. For those sources, the commenters acknowledge that permit
writers must retain the legal authority to place additional operating
limitations in a source's permit.
As noted above, the omnibus provision is a RCRA statutory
requirement and does not have a CAA counterpart. The CAA does not
override RCRA. Each statute continues to apply to hazardous waste
combustors unless we determine there is duplication and use the RCRA
section 1006(b) deferral authority to create a specific regulatory
exemption.18 Promulgation of the MACT standards, therefore,
does not duplicate, supersede, or otherwise modify the omnibus
provision or its applicability to sources subject to today's
rulemaking. As indicated in the April 1996 NPRM, a RCRA permitting
authority (such as a state agency) has the responsibility to supplement
the national MACT standards as necessary, on a site-specific basis, to
ensure adequate protection under RCRA. We recognize that this could
result in a situation in which a source may be subject to emission
standards and operating conditions under two regulatory authorities
(i.e., CAA and RCRA). Although our intent, consistent with the
integration provision of RCRA section 1006(b), is to avoid regulatory
duplication to the maximum extent practicable, we may not eliminate
RCRA requirements if a source's emissions are not protective of human
health and the environment when complying with the MACT
standards.19
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\18\ The risk-based permit conditions are in addition to those
conditions required by the RCRA national regulatory standards for
hazardous waste combustors (e.g., general facility requirements).
\19\ RCRA section 1006(b) authorizes deferral of RCRA provisions
to other EPA-implemented authorities provided, among other things,
that key RCRA policies and protections are not sacrificed. See
Chemical Waste Management v. EPA, 976 F. 2d 2, 23, 25 (D.C. Cir.
1992).
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B. How Will the SSPA Policy Be Applied and Implemented in Light of This
Mandate?
1. Is There a Continuing Need for Site-Specific Risk Assessments?
As stated previously, EPA's Hazardous Waste Minimization and
Combustion Strategy recommended that SSRAs be conducted as part of the
RCRA permitting process for hazardous waste combustors where necessary
to protect human health and the environment. We intended to reevaluate
this policy once the national hazardous waste combustion standards had
been updated. We view today's MACT standards as more stringent than
those earlier standards for incinerators, cement kilns and lightweight
aggregate kilns. To determine if the MACT standards as proposed in the
April 1996 NPRM would satisfy the RCRA mandate to protect human health
and the environment, we conducted a national evaluation of both human
health and ecological risk. That evaluation, however, did not
quantitatively assess the proposed standards with respect to mercury
and nondioxin products of incomplete combustion. This was due to a lack
of adequate information regarding the behavior of mercury in the
environment and a lack of sufficient emissions data and parameter
values (e.g., bioaccumulation values) for nondioxin products of
incomplete combustion. Since it was not possible to suitably evaluate
the proposed standards for the potential risk posed by mercury and
nondioxin products of incomplete combustion, we elected in the April
1996 NPRM to continue recommending that SSRAs be conducted as part of
the permitting process until we could conduct a further assessment once
final MACT standards are promulgated and implemented.
Although some commenters agree with this approach, a number of
other commenters question the necessity of a quantitative nondioxin
product of incomplete combustion assessment to demonstrate RCRA
protectiveness of the MACT standards. These commenters
[[Page 52841]]
assert that existing site-specific assessments demonstrate that
emissions of nondioxin products of incomplete combustion are unlikely
to produce significant adverse human health effects. However, we do not
agree that sufficient SSRA information exists to conclude that
emissions from these compounds are unlikely to produce significant
adverse effects on human health and the environment on a national
basis. First, only a limited number of completed SSRAs are available
from which broader conclusions can be drawn. Second, nondioxin products
of incomplete combustion emissions can vary widely depending on the
type of combustion unit, hazardous waste feed and air pollution control
device used. Third, a significant amount of uncertainty exists with
respect to identifying and quantifying these compounds. Many nondioxin
products of incomplete combustion cannot be characterized by standard
analytical methodologies and are unaccounted for by standard emissions
testing.20 (On a site-specific basis, uncharacterized
nondioxin products of incomplete combustion are typically addressed by
evaluating the total organic emissions.) Fourth, nondioxin products of
incomplete combustion can significantly contribute to the overall risk
posed by a particular facility. For example, in the Waste Technologies
Industries incinerator's SSRA, nondioxin organics were estimated to
contribute approximately 30% of the total cancer risk to the most
sensitive receptor located in the nearest subarea to the
facility.21 Fifth, national risk management decisions
concerning the protectiveness of the MACT standards must be based on
data that are representative of the hazardous waste combustors subject
to today's rulemaking. We do not believe that the information afforded
by the limited number of SSRAs now available is sufficiently complete
or representative to render a national decision.22
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\20\ USEPA, ``Development of a Hazardous Waste Incinerator
Target Analyte List of Products of Incomplete Combustion'' EPA-600/
R-98-076. 1998.
\21\ The total cancer risk for this receptor was 1 x 10E-6. The
results derived for the Waste Technologies Industries incinerator's
SSRA are a combination of measurements and conservative estimates of
stack and fugitive emissions, which were developed in tandem with an
independent external peer review. USEPA, ``Risk Assessment for the
Waste Technologies Industries Hazardous Waste Incineration Facility
(East Livepool, Ohio)'' EPA-905-R97-002.
\22\ Since publication of the April 1996 NPRM, we have expanded
our national risk evaluation of the other hazardous waste combustor
emissions (e.g., metals) from 11 facilities to 76 facilities
assessed for today's final rulemaking. The 76 facilities were
selected using a stratified random sampling approach that allowed
for a 90 percent probability of including at least one ``high risk''
facility. However, this larger set of facility assessments does not
include an evaluation nondioxin products of incomplete combustion.
See Part Five, Section XIII for further discussion.
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Some commenters recommend discontinuing conducting SSRAs
altogether. Other commenters, however, advocate continuing to conduct
SSRAs, where warranted, as a means of addressing uncertainties inherent
in the national risk evaluation and of addressing unique, site-specific
circumstances not considered in the assessment.
In developing the national risk assessment for the final MAC
standards, we expanded our original analysis to include a quantitative
assessment of mercury patterned after the recently published Mercury
Study Report to Congress.23 We were unable to perform a
similar assessment of nondioxin products of incomplete combustion
emissions because of continuing data limitations for these compounds,
despite efforts to collect additional data since publication of the
April 1996 NPRM . Thus, we conclude that sufficient data are not
available to quantitatively assess the potential risk from these
constituents on a national level as part of today's rulemaking.
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\23\ USEPA, ``Mercury Study Report to Congress, Volume III: Fate
and Transport of Mercury in the Environment,'' EPA 452/R-97-005,
December 1997.
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Given the results of the final national risk assessment for other
hazardous air pollutants, we generally anticipate that sources
complying with the MACT standards will not pose an unacceptable risk to
human health or the environment. However, we cannot make a definitive
finding in this regard for all hazardous waste combustors subject to
today's MACT standards for the reasons discussed.
First, as discussed above, the national risk evaluation did not
include an assessment of the risk posed by nondioxin products of
incomplete combustion. As reflected in the Waste Technologies
Industries SSRA, these compounds can significantly contribute to the
overall risk posed by a hazardous waste combustor. Without a
quantitative evaluation of these compounds, we cannot reliably predict
whether the additional risk contributed by nondioxin products of
incomplete combustion would or would not result in an unacceptable
increase in the overall risk posed by hazardous waste combustors
nationally.
Second, the quantitative mercury risk analysis conducted for
today's rulemaking contains significant uncertainties. These
uncertainties limit the use of the analysis for drawing quantitative
conclusions regarding the risks associated with the national mercury
MACT standard. Among others, the uncertainties include an incomplete
understanding of the fate and transport of mercury in the environment
and the biological significance of exposures to mercury in fish. (See
Part Five, Section XIII.) Given these uncertainties, we believe that
conducting a SSRA, which will assist a permit writer to reduce
uncertainty on a site-specific basis, may be still warranted in some
cases.24 As the science regarding mercury fate and transport
in the environment and exposure improves, and greater certainty is
achieved in the future, we may be in a better position from which to
draw national risk management conclusions regarding mercury risk.
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\24\ An example of the possible reduction in uncertainty which
may be derived through the performance of a SSRA includes the degree
of conversion of mercury to methyl mercury in water bodies. Due to
the wide range of chemical and physical properties associated with
surface water bodies, there appears to be a great deal of
variability concerning mercury methylation. In conducting a SSRA, a
risk assessor may choose to use a default value to represent the
percentage of mercury assumed to convert to methyl mercury.
Conversely, the risk assessor may choose to reduce the uncertainty
in the analysis by deriving a site-specific value using actual
surface water data. Chemical and physical properties that may
influence mercury methylation include, but are not limited to:
dissolved oxygen content, pH, dissolved organic content, salinity,
nutrient concentrations, and temperature. See USEPA, ``Human Health
Risk Assessment Protocol for Hazardous Waste Combustion
Facilities,'' EPA-530-D-98-001A, External Peer Review Draft, 1998.
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Third, we agree with commenters who indicated that, by its very
nature, the national risk assessment, while comprehensive, cannot
address unique, site-specific risk considerations \25\ As a result of
these considerations, a separate analysis or ``risk check'' may be
necessary to verify that the MACT standards will be adequately
protective under RCRA for a given hazardous waste combustor.
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\25\ Including for example, unusual terrain or dispersion
features, particularly sensitive ecosystems, unusually high
contaminant background concentrations, and mercury methylation rates
in surface water.
---------------------------------------------------------------------------
Thus, we are recommending that for hazardous waste combustors
subject to the Phase I final MACT standards, permitting authorities
should evaluate the need for a SSRA on a case-by-case
basis.26 SSRAs are not anticipated to be necessary for every
facility, but should be conducted for facilities where there is some
reason to believe that operation
[[Page 52842]]
in accordance with the MACT standards alone may not be protective of
human health and the environment. If a SSRA does demonstrate that
operation in accordance with the MACT standards may not be protective
of human health and the environment, permitting authorities may require
additional conditions as necessary. We consider this an appropriate
course of action to ensure protection of human health and the
environment under RCRA, given current limits to our scientific
knowledge and risk assessment tools.
---------------------------------------------------------------------------
\26\ We continue to recommend that for those HWCs not subject to
the Phase I final MACT standards, as SSRA should be conducted as
part of the RCRA permitting process.
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2. How Will the SSRA Policy Be Implemented?
Some commenters suggest that EPA provide regulatory language
specifically requiring SSRAs. Adequate authority and direction already
exists to require SSRAs on a case-by-case basis through current
regulations and guidance (none of which are being reconsidered, revised
or otherwise reopened in today's rulemaking). The omnibus provision
(codified in 40 CFR 270.32(b)(2)) directs the RCRA permitting authority
to include terms and conditions in the RCRA permit as necessary to
ensure protection of human health and the environment. Under 40 CFR
270.10(k), the permitting authority may require a permittee or permit
applicant to submit information where the permitting authority has
reason to believe that additional permit conditions may be warranted
under Sec. 270.32(b)(2). Performance of a SSRA is a primary, although
not exclusive mechanism by which the permitting authority may develop
the information necessary to make the determination regarding what, if
any, additional permit conditions are needed for a particular hazardous
waste combustor. Thus, for hazardous waste combustors, the information
required to establish permit conditions could include a SSRA, or the
necessary information required to conduct a SSRA.
In 1994, we provided guidance concerning the appropriate
methodologies for conducting hazardous waste combustor
SSRAs.27 This guidance was updated in 1998 and released for
publication as an external peer review draft.28 We
anticipate that use of the updated and more detailed guidance will
result in a more standardized assessments for hazardous waste
combustors.
---------------------------------------------------------------------------
\27\ USEPA. ``Guidance for Performing Screening Level Risk
Analyses at Combustion Facilities Burning Hazardous Wastes'' Draft,
April 1994; USEPA. ``Implementation of Exposure Assessment Guidance
for RCRA Hazardous Waste Combustion Facilities'' Draft, 1994.
\28\ USEPA. ``Human Health Risk Assessment Protocol for
Hazardous Waste Combustion Facilities'' EPA-520-D-98-001A, B&C.
External Peer Review Draft, 1998.
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To implement the RCRA SSRA policy, we expect permitting authorities
to continue evaluating the need for an individual hazardous waste
combustor risk assessment on a case-by-case basis. We provided a list
of qualitative guiding factors in the April 1996 NPRM to assist in this
determination. One commenter is concerned that the subjectivity
inherent in the list of guiding factors might lead to inconsistencies
when determining if a SSRA is necessary and suggested that we provide
additional guidance on how the factors should be used. We continue to
believe that the factors provided, although qualitative, generally are
relevant to the risk potential of hazardous waste combustors and
therefore should be considered when deciding whether or not a SSRA is
necessary. However, as a practical matter, the complexity of the
multipathway risk assessment methodology precludes conversion of these
qualitative factors into more definitive criteria. We will continue to
compile data from SSRAs to determine if there are any trends which
would assist in developing more quantitative or objective criteria for
deciding on the need for a SSRA at any given site. In the interim,
SSRAs provide the most credible basis for comparisons between risk-
based emission limits and the MACT standards.
The commenter further suggests that EPA emphasize that the factors
should be considered collectively due to their complex interplay (e.g.,
exposure is dependent on fate and transport which is dependent on
facility characteristics, terrain, meteorological conditions, etc.). We
agree with the commenter. The elements comprising multipathway risk
assessments are highly integrated. Thus, the considerations used in
determining if a SSRA is necessary are similarly interconnected and
should be evaluated collectively.
The guiding factors as presented in the April 1996 NPRM contained
several references to the proposed MACT standards. As a result, we
modified and updated the list to reflect promulgation of the final
standards and to re-focus the factors to specifically address the types
of considerations inherent in determining if a SSRA is necessary. The
revised guiding factors are: (1) Particular site-specific
considerations such as proximity to receptors, unique dispersion
patterns, etc.; (2) identities and quantities of nondioxin products of
incomplete combustion most likely to be emitted and to pose significant
risk based on known toxicities (confirmation of which should be made
through emissions testing); (3) presence or absence of other off-site
sources of pollutants in sufficient proximity so as to significantly
influence interpretation of a facility-specific risk assessment; (4)
presence or absence of significant ecological considerations, such as
high background levels of a particular contaminant or proximity of a
particularly sensitive ecological area; (5) volume and types of wastes
being burned, for example wastes containing highly toxic constituents
both from an acute and chronic perspective; (6) proximity of schools,
hospitals, nursing homes, day care centers, parks, community activity
centers that would indicate the presence of potentially sensitive
receptors; (7) presence or absence of other on-site sources of
hazardous air pollutants so as to significantly influence
interpretation of the risk posed by the operation of the source in
question; and (8) concerns raised by the public. The above list of
qualitative guiding factors is not intended to be all-inclusive; we
recognize that there may be other factors equally relevant to the
decision of whether or not a SSRA is warranted in particular
situations.
With respect to existing hazardous waste combustion sources, we do
not anticipate a large number of SSRAs will need to be performed after
the compliance date of the MACT standards. SSRAs already have been
initiated for many of these sources. We strongly encourage facilities
and permitting authorities to ensure that the majority of those risk
assessments planned or currently in progress be completed prior to the
compliance date of the MACT standards. The results of these assessments
can be used to provide a numerical baseline for emission limits. This
baseline then can be compared to the MACT limits to determine if site-
specific risk-based limits are appropriate in addition to the MACT
limits for a particular source.
Several commenters suggest that completed risk assessments should
not have to be repeated. We do not anticipate repeating many risk
assessments. It should be emphasized that changes to comply with the
MACT standards should not cause an increase in risk for the vast
majority of the facilities given that the changes, in all probability,
will be the addition of pollution control equipment or a reduction in
the hazardous waste being burned. For those few situations in which the
MACT requirements might result in increased potential risk for a
particular facility due to unique site-specific considerations, the
RCRA permit writer, however, may determine
[[Page 52843]]
that a risk check of the projected MACT emission rates is in
order.29 Should the results of the risk check demonstrate
that compliance with the MACT requirements does not satisfy the RCRA
protectiveness mandate, the permitting authority should invoke the
omnibus provision to impose more stringent, site-specific, risk-based
permit conditions as necessary to protect human health and the
environment.
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\29\ For example, hazardous waste burning cement kilns that
previously monitored hydrocarbons in the main stack may elect to
install a mid-kiln sampling port for carbon monoxide or hydrocarbon
monitoring to avoid restrictions on hydrocarbon levels in the main
stack. Thus, their stack hydrocarbon emissions may increase.
---------------------------------------------------------------------------
With respect to new hazardous waste combustors and existing
combustors for which a SSRA has never been conducted, we recommend that
the decision of whether or not a SSRA is necessary be made prior to the
approval of the MACT comprehensive performance test protocol, thereby
allowing for the collection of risk emission data at the same time as
the MACT performance testing, if appropriate (see Part Five, Section
V). In those instances where it has been determined a SSRA is
appropriate, the assessment should take into account both the MACT
standards and any relevant site-specific considerations.
We emphasize that the incorporation of site-specific, risk-based
permit conditions into a permit is not anticipated to be necessary for
the vast majority of hazardous waste combustors. Rather, such
conditions would be necessary only if compliance with the MACT
requirements is insufficient to protect human health and the
environment pursuant to the RCRA mandate and if the resulting risk-
based conditions are more stringent than those required under the CAA.
Risk-based permit conditions could include, but are not limited to,
more stringent emission limits, additional operating parameter limits,
waste characterization and waste tracking requirements.
C. What Is the Difference Between the RCRA SSRA Policy and the CAA
Residual Risk Requirement?
Section 112(f) of the CAA requires the Agency to conduct an
evaluation of the risk remaining for a particular source category after
compliance with the MACT standards. This evaluation of residual risk
must occur within eight years of the promulgation of the MACT standards
for each source category. If it is determined that the residual risk is
unacceptable, we must impose additional controls on that source
category to protect public health with an ample margin of safety and to
prevent adverse environmental effects.
Our SSRA policy is intended to address the requirements of the RCRA
protectiveness mandate, which are different from those provided in the
CAA. For example, the omnibus provision of RCRA requires that the
protectiveness determination be made on a permit-by-permit or site-
specific basis. The CAA residual risk requirement, conversely, requires
a determination be made on a source category basis. Further, the time
frame under which the RCRA omnibus determination is made is more
immediate; the SSRA is generally conducted prior to final permit
issuance. The CAA residual risk determination, on the other hand, is
made at any time within the eight-year time period after promulgation
of the MACT standards for a source category. Thus, the possibility of a
future section 112(f) residual risk determination does not relieve RCRA
permit writers of the present obligation to determine whether the RCRA
protectiveness requirement is satisfied. Finally, nothing in the RCRA
national risk evaluation for this rule should be taken as establishing
a precedent for the nature or scope of any residual risk procedure
under the CAA.
Part Four: What Is the Rationale for Today's Final Standards?
I. Emissions Data and Information Data Base
A. How Did We Develop the Data Base for This Rule?
To support the emissions standards in today's rule, we use a
``fourth generation'' data base that considers and incorporates public
comments on previous versions of the data base. This final data base
24 summarizes emissions data and ancillary information on
hazardous waste combustors that was primarily extracted from
incinerator trial burn reports and cement and lightweight aggregate
kiln Certification of Compliance test reports prepared as part of the
compliance process for the current regulatory standards. Ancillary
information in the data base includes general facility information
(e.g., location) process operating data (e.g., waste, fuel, raw
material compositions, feed rates), and facility equipment design and
operational information (e.g., air pollution control device
temperatures).
---------------------------------------------------------------------------
\24\ USEPA, ``Final Technical Support Document for HWC MACT
Standards, Volume II: HWC Emissions Database,'' July 1999.
---------------------------------------------------------------------------
The data base supporting the April 1996 proposal was the initial
data base released for public comment.25 We received a
substantial number of public comments on this data base including
identification of data errors and submission of many new trial burn and
compliance test reports not already in the data base. Subsequently, we
developed a ``second generation'' data base addressing these comments
and, on January 7, 1997, published a NODA soliciting public comment on
the updated data base. Numerous industry stakeholders submitted
comments on the second generation data base. The data base was revised
again to accommodate these public comments resulting in a ``third
generation'' data base. We also published for comment a document
indicating how specific public comments submitted in response to the
January NODA were addressed.26 In the May 1997 NODA, we used
this third generation data base to re-evaluate the MACT standards.
Since the completion of the third generation data base, we have
incorporated additional data base comments and new test reports
resulting in the ``fourth generation'' data base. This final data base
is used to support all MACT analyses discussed in today's rule.
Compared to the changes made to develop the third generation data base,
those changes made in the fourth generation are relatively minor. The
majority of these changes (e.g., incorporating a few trial burn reports
and incorporating suggested revisions to the third generation data
base) were in response to public comments received to May 1997 NODA.
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\25\ USEPA, ``Draft Technical Support Document for HWC MACT
Standards, Volume II: HWC Emissions Database,'' February 1996.
\26\ See USEPA, ``Draft Report of Revisions to Hazardous Waste
Combustor Database Based on Public Comments Submitted in Response to
the January 7, 1997 Notice of Data Availability (NODA),'' May 1997.
---------------------------------------------------------------------------
B. How Are Data Quality and Data Handling Issues Addressed?
We selected approaches to resolve several data quality and handling
issues regarding: (1) Data from sources no longer burning hazardous
waste; (2) assigning values to reported nondetect measurements; (3)
data generated under normal conditions versus worst-case compliance
conditions; and (4) use of imputation techniques to fill in missing or
unavailable data. This section discusses our selected approaches to
these four issues.
[[Page 52844]]
1. How Are Data From Sources No Longer Burning Hazardous Waste Handled?
Data and information from sources no longer burning hazardous waste
are not considered in the MACT standards evaluations promulgated today.
We note that some facilities have recently announced plans to cease
burning hazardous waste. Because we cannot continually adjust our data
base and still finalize this rulemaking, we concluded revisions to the
data base in early 1998. Announcements or actual facility changes after
that date simply could not be incorporated.
Numerous commenters responded to our request for comment on the
appropriate approach to handle emissions data from sources no longer
burning hazardous waste. In the April 1996 proposal, we considered all
available data, including data from sources that had since ceased waste
burning operations. However, in response to comments to the April 1996
NPRM, in the May 1997 NODA we excluded data from sources no longer
burning hazardous waste and reevaluated the MACT floors with the
revised data base. Of the data included in the fourth generation data
base, the number of sources that have ceased waste burning operations
include 18 incineration facilities comprising 18 sources; eight cement
kiln facilities comprising 12 sources; and one lightweight aggregate
kiln facility comprising one source.
Several commenters support the inclusion in the MACT analyses of
data from sources no longer burning hazardous waste. They believe the
performance data from these sources are representative of emissions
control achievable when burning hazardous waste because the data were
generated under compliance testing conditions. Other commenters suggest
that data from sources no longer burning hazardous waste should be
excluded from consideration when conducting MACT floor analyses to
ensure that the identified MACT floor levels are achievable.
The approach we adopt today is identical to the one we used for the
May 1997 NODA. Rather than becoming embroiled in a controversy over
continued achievability of the MACT standards, we exercise our
discretion and use a data base consisting of only facilities now
operating (at least as of the data base finalization date). Ample data
exist to support setting the MACT standards without using data from
facilities that no longer burn hazardous waste. To the extent that some
previous data from facilities not now burning hazardous waste still
remain in the data base, we ascribe to the view that these data are
representative of achievable emissions control and can be used.
2. How Are Nondetect Data Handled?
In today's rule, as in the May 1997 NODA, we evaluated nondetect
values, extracted from compliance test reports and typically associated
with feedstream input measurements rather than emissions
concentrations, as concentrations that are present at one-half the
detection limit. In the proposal, we assumed that nondetect analyses
were present at the value of the full detection limit.
Some commenters support our approach to assume that nondetect
values are present at one-half the detection limit. The commenter
states that this approach is consistent with the data analysis
techniques used in other EPA environmental programs such as in the
evaluation of groundwater monitoring data. Other commenters oppose
treating nondetect values at one-half the detection limit, especially
for dioxins/furans because Method 23 for quantitating stack emissions
states that nondetect values for congeners be treated as zero when
calculating total congeners and the toxicity equivalence quotient for
dioxins/furans. As explained in the NODA, the assumption that nondetect
measurements are present at one-half the reported detection limit is
more technically and environmentally conservative and increases our
confidence that standards and risk findings are appropriate. Further,
we considered assuming that nondetect values were present at the full
detection limit, but found that there were no significant differences
in the MACT data analysis results.27 Therefore, in today's
rule, we assume nondetect measurements are present at one-half the
detection limit.
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\27\ Using dioxins and furans as an example, for those sources
using MACT control, this difference is no more than approximately 10
percent of the standard. USEPA, ``Final Technical Support Document
for HWC MACT Standards, Volume III: Selection of MACT Standards and
Technologies,'' July 1999.
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3. How Are Normal Versus Worst-Case Emissions Data Handled?
The majority of the available emissions data for all of the
hazardous air pollutants except mercury can be considered worst-case
because they were generated during RCRA compliance testing. Because
limits on operating parameters are established based on compliance test
operations, sources generally operate during compliance testing under
worst-case conditions to account for variability in operations and
emissions. However, the data base also contains some normal data for
these hazardous air pollutants. Normal data include those where
hazardous waste was burned, but neither spiking of the hazardous waste
with metals or chlorine nor operation of the combustion unit and
emission control equipment under detuned conditions occurred.
In the MACT analyses supporting today's rule, normal data were not
used to identify or define MACT floor control, with the exception of
mercury, as discussed below. This approach is identical to the one used
in the May 1997 NODA. 62 FR 24216.
Several commenters support the use of normal emissions data in
defining MACT controls because the effect of ignoring the potentially
lower emitters from these sources would skew the analysis to higher
floor results. Other commenters oppose the use of normal data because
they would not be representative of emissions under compliance test
conditions--the conditions these same sources will need to operate
under during MACT performance tests to establish limits on operating
conditions.28
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\28\ These commenters are concerned that, if the standards were
based on normal emissions data, sources would be inappropriately
constrained to emissions that are well below what is currently
normal. This is because of the double ratcheting effect of the
compliance regime whereby a source must first operate below the
standard during compliance testing, and then again operate below
compliance testing levels (and associated operating parameters) to
maintain day-to-day compliance.
---------------------------------------------------------------------------
We conclude that it is inappropriate to perform the MACT floor
analysis for a particular hazardous air pollutant using emissions data
that are a mixture of normal and worst-case data. The few normal
emissions data would tend to dominate the identification of best
performing sources while not necessarily being representative of the
range of normal emissions. Because the vast majority of our data is
based on worst-case compliance testing, the definition of floor control
is based on worst-case data.29 Using worst-case emissions
data to establish a MACT
[[Page 52845]]
floor also helps account for emissions variability, as discussed in
Section V.D. below.
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\29\ We considered adjusting the emissions data to account for
spiking to develop a projected normal emissions data base. However,
we conclude that this is problematic and have not done so. For
example, it is difficult to project (lower) emissions from
semivolatile metal-spiked emissions data given that system removal
efficiency does not correlate linearly with semivolatile metal
feedrate. In addition, we did not know for certain whether some data
were spiked. Thus, we would have to use either a truncated data base
of despiked data or a mixed data base of potentially spiked data and
despiked data, neither of which would be fully satisfactory.
---------------------------------------------------------------------------
Sources did not generally spike mercury emissions during RCRA
compliance testing because they normally feed mercury at levels
resulting in emissions well below current limits.30
Consequently, sources are generally complying with generic,
conservative feedrate limits established under RCRA rather than
feedrate limits established during compliance testing. Because our data
base is comprised essentially of normal emissions, we believe this is
one instance where use of normal data to identify MACT floor is
appropriate. See discussion in Section V.D. below of how emissions
variability is addressed for the mercury floors.
---------------------------------------------------------------------------
\30\ Three of 23 incinerators used to define MACT floor (i.e.,
sources for which mercury feedrate data are available) are known to
have spiked mercury. No cement kilns used to define MACT floor
(e.g., excluding sources that have stopped burning hazardous waste)
are known to have spiked mercury. Only one of ten lightweight
aggregate kilns used to define MACT floor is known to have spiked
mercury.
---------------------------------------------------------------------------
4. What Approach Was Used To Fill In Missing or Unavailable Data?
With respect to today's rule, the term ``imputation'' refers to a
data handling technique where a value is filled-in for a missing or
unavailable data point. We only applied this technique to hazardous air
pollutants that are comprised of more than one pollutant (i.e.,
semivolatile metals, low volatile metals, total chlorine). We used
imputation techniques in both the proposal and May 1997 NODA; however,
we decided not to use imputation procedures in the development of
today's promulgated standards. We used only complete data sets in our
MACT determinations. Several commenters to the proposal and May 1997
NODA oppose the use of imputation techniques. Commenters express
concern that the imputation approach used in the proposal did not
preserve the statistical characteristics (average and standard
deviation) of the entire data set. Thus, commenters suggest that
subsequent MACT analyses were flawed. We reevaluated the data base and
determined that a sufficient number of data sets are complete without
the use of an imputation technique.31 A complete discussion
of various data handling conventions is presented in the technical
support document.32
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\31\ This is especially true because antimony is no longer
included in the low volatile metal standard.
\32\ See USEPA, ``Final Technical Support Document for HWC MACT
Standards, Volume III: Selection of MACT Standards and
Technologies,'' July 1999.
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II. How Did We Select the Pollutants Regulated by This Rule?
Section 112(b) of the Clean Air Act, as amended, provides a list of
188 33 hazardous air pollutants for which the Administrator
must promulgate emission standards for designated major and area
sources. The list is comprised of metal, organic, and inorganic
compounds.
---------------------------------------------------------------------------
\33\ The initial list consisted of 189 HAPs, but we have removed
caprolactam (CAS number 105602) from the list of hazardous air
pollutants. See Sec. 63.60.
---------------------------------------------------------------------------
Hazardous waste combustors emit many of the hazardous air
pollutants. In particular, hazardous waste combustors can emit high
levels of dioxins and furans, mercury, lead, chromium, antimony, and
hydrogen chloride. In addition, hazardous waste combustors can emit a
wide range of nondioxin/furan organic hazardous air pollutants,
including benzene, chloroform, and methylene chloride.
In today's rule, we establish nine emission standards to control
hazardous air pollutants emitted by hazardous waste combustors.
Specifically, we establish emission standards for the following
hazardous air pollutants: Chlorinated dioxins and furans, mercury, two
semivolatile metals (i.e., lead and cadmium), three low volatility
metals (i.e., arsenic, beryllium, chromium), and hydrochloric acid/
chlorine gas. In addition, MACT control is provided for other hazardous
air pollutants via standards for surrogates: (1) A standard for
particulate matter will control five metal hazardous air pollutants--
antimony, cobalt, manganese, nickel, and selenium; and (2) standards
for carbon monoxide, hydrocarbons, and destruction and removal
efficiency will control nondioxin/furan organic hazardous air
pollutants.
A. Which Toxic Metals Are Regulated by This Rule? 34
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\34\ RCRA standards currently control emissions of three toxic
metals that have not been designated as Clean Air Act hazardous air
pollutants: Barium, silver, and thallium. These RCRA metals are
incidentally controlled by today's MACT controls for metal hazardous
air pollutants in two ways. First, the RCRA metals are semivolatile
or nonvolatile and will, in part, be controlled by the air pollution
control systems used to meet the semivolatile metal and low volatile
metal standards in today's rule. Second, these RCRA metals will be
controlled by the measures used to meet today's MACT participate
matter standard. See text that follows.
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1. Semivolatile and Low Volatile Metals
The Section 112(b) list of hazardous air pollutants includes 11
metals: antimony, arsenic, beryllium, cadmium, chromium, cobalt, lead,
manganese, mercury, nickel, and selenium. To establish an implementable
approach for controlling these metal hazardous air pollutants, we
proposed to group the metals by their relative volatility and
established emission standards for each volatility group. We placed six
of the eleven metals in volatility groups. The high-volatile group is
comprised of mercury, the semivolatile group is comprised of lead and
cadmium, and the low volatile group is comprised of arsenic, beryllium,
and chromium.35 We refer to these six metals for which we
have established standards based on volatility group as ``enumerated
metals.'' We have chosen to control the remaining five metals using
particulate matter as a surrogate as discussed in the next section.
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\35\ Antimony was included in the low volatile group at
proposal, but we subsequently determined that the MACT particulate
matter standard serves as an adequate surrogate for this metal. See
the May 1997 NODA (62 FR at 24216). In making this determination, we
noted that antimony is an noncarcinogen with relatively low toxicity
compared with the other five nonmercury metals that were placed in
volatility groups. To be of particular concern, antimony would have
to be present in hazardous waste at several orders of magnitude
higher than shown in the available data.
---------------------------------------------------------------------------
Grouping metals by volatility is reasonable given that emission
control strategies are governed primarily by a metal's volatility. For
example, while semivolatile metals and low volatile metals are in
particulate form in the emission control train and can be removed as
particulate matter, mercury species are generally emitted from
hazardous waste combustors in the vapor phase and cannot be controlled
by controlling particulate matter unless a sorbent, such as activated
carbon, is injected into the combustion gas. In addition, low volatile
metals are easier to control than semivolatile metals because
semivolatile metals volatilize in the combustion chamber and condense
on fine particulate matter, which is somewhat more difficult to
control. Low volatile metals do not volatilize significantly in
hazardous waste combustors and are emitted as larger, easier to remove,
particles entrained in the combustion gas.36
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\36\ The dynamics associated with the fate of metals in a
hazardous waste combustor are much more complex than presented here.
For more information, see USEPA, ``Draft Technical Support Document
for HWC MACT Standards, Volume VII: Miscellaneous Technical
Issues,'' February 1996.
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Commenters agree with our proposal to group metals by their
relative volatility. We adopt these groupings for the final rule.
We note that the final rule does not require a source to control
its particulate matter below the particulate matter standard to control
semivolatile and low
[[Page 52846]]
volatile metals. It is true that when we were determining the
semivolatile and low volatile metal floor standards, we did examine the
feedrates from only those facilities that were meeting the numerical
particulate standard. See Part Four, Section V.B.2.c. This is because
we believe that facilities, in practice, use both feedrate and
particulate matter air pollution control devices in a complementary
manner to address metals emissions (except mercury). However, our
setting of the semivolatile and low volatile metal floor standards does
not require MACT particulate matter control to be installed, either
directly or indirectly, as a matter of CAA compliance. We do not think
it is necessary to require compliance with a particulate matter
standard as an additional express element of the semivolatile/low
volatile metal emission standards because the particulate matter
standard is already required to control the nonenumerated metals, as
discussed below. However, we could have required compliance with a
particulate matter standard as part of the semivolatile or low volatile
metal emission standard because of the practice of using particulate
matter control as at least part of a facility's strategy to control or
minimize metal emissions (other than mercury).
2. How Are the Five Other Metal Hazardous Air Pollutants Regulated?
We did not include five metal hazardous air pollutants (i.e.,
antimony, cobalt, manganese, nickel, selenium) in the volatility groups
because of: (1) Inadequate emissions data for these metals
37; (2) relatively low toxicity of antimony, cobalt, and
manganese; and (3) the ability to achieve control, as explained below,
by means of surrogates. Instead, we chose the particulate matter
standard as a surrogate control for antimony, cobalt, manganese,
nickel, and selenium. We refer to these five metals as ``nonenumerated
metals'' because standards specific to each metal have not been
established. We conclude that emissions of these metals is effectively
controlled by the same air pollution control devices and systems used
to control particulate matter.
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\37\ USEPA, ``Final Technical Support Document for HWC MACT
Standards, Volume II: HWC Emissions Database,'' July 1999.
---------------------------------------------------------------------------
Some commenters suggest that particulate matter is not a surrogate
for the five nonenumerated metals. Commenters also note that our own
study, as well as investigations by commenters, did not show a
relationship between particulate matter and semivolatile metals and low
volatile metals when emissions from multiple sources were considered.
However, we conclude that such a relationship is not expected when
multiple sources are considered because wide variations in source
operations can affect: (1) Metals and particulate matter loadings at
the inlet to the particulate matter control device; (2) metals and
particulate matter collection efficiency; and (3) metals and
particulate matter emissions. Factors that can contribute to
variability in source operations include metal feed rates, ash levels,
waste types and physical properties (i.e., liquid vs. solid),
combustion temperatures, and particulate matter device design,
operation, and maintenance.
Conversely, emissions of semivolatile metals and low volatile
metals are directly related to emissions of particulate matter at a
given source when other operating conditions are held constant (i.e.,
as particulate matter emissions increase, emissions of these metals
also increase) because semivolatile metals and low volatile metals are
present as particulate matter at the typical air pollution control
device temperatures of 200 to 400 deg.F that are required under today's
rule.38 A strong relationship between particulate matter and
semivolatile/low volatile metal emissions is evident from our emissions
data base of trial burn emissions at individual sources where
particulate matter varies and metals feedrates and other conditions
that may affect metals emissions were held fairly constant. Other work
also has clearly demonstrated that improvement in particulate control
leads to improved metals control.39
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\38\ The dioxin/furan emission standard requires that gas
temperatures at the inlet to electrostatic precipitators and fabric
filters not exceed 400 deg.F. Wet particulate matter control devices
reduce gas temperatures to below 400 deg.F by virtue of their design
and operation. The vapor phase contribution (i.e., nonparticulate
form that will not be controlled by a particulate matter control
device) of semivolatile metal and low volatile metal at these
temperatures is negligible.
\39\ USEPA, ``Final Technical Support Document for HWC MACT
Standards, Volume III: Selection of MACT Standards and
Technologies,'' July 1999.
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We also requested comment on whether particulate matter could be
used as a surrogate for all semivolatile and low volatile metal
hazardous air pollutants (i.e., all metal hazardous air pollutants
except mercury). See the May 1997 NODA. This approach is strongly
recommended by the cement industry. In that Notice, we concluded that,
because of varying and high levels of metals concentrations in
hazardous waste, use of particulate matter control alone may not
provide MACT control for metal hazardous air pollutants.40
Our conclusion is the same today. Without metal-specific MACT emission
standards or MACT feedrate standards, sources could feed high levels of
one or more metal hazardous air pollutant metals. This practice could
result in high metal emissions, even though the source's particulate
matter is controlled to the emission standard (i.e., a large fraction
of emitted particulate matter could be comprised of metal hazardous air
pollutants). Thus, the use of particulate matter control alone would
not constitute MACT control of that metal and would be particularly
troublesome for the enumerated semivolatile and low volatile metal
because of their toxicity.41
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\40\ However, for sources not burning hazardous waste and
without a significant potential for extreme variability in metals
feedrates, particulate matter is an adequate surrogate for metal
hazardous air pollutants (e.g., for nonhazardous waste burning
cement kilns).
\41\ Using particulate matter as a surrogate for metals is,
however, the approach we used in the final rule for five metals:
Antimony, cobalt, manganese, nickel, selenium. Technical and
practical reasons unique to these metals support this approach.
First, these metals exhibit relatively low toxicity. Second, for
some of these metals, we did not have emissions data adequate to
establish specific standards. Therefore, the best strategy for these
particular metals, at this time, is to rely on particulate matter as
a surrogate.
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Many commenters suggest that particulate matter is an adequate
surrogate for all metal hazardous air pollutants. They suggest that,
given current metal feedrates and emission rates, particularly in the
cement industry, a particulate matter standard is sufficient to ensure
that metal hazardous air pollutants (other than mercury) are controlled
to levels that would not pose a risk to human health or the
environment. While this may be true in some cases as a theoretical
matter, it may not be in all cases. Data demonstrating this
conclusively were not available for all cement kilns. Moreover, this
approach may not ensure MACT control of the potentially problematic
(i.e., high potential risk) metals for reasons discussed above (i.e.,
higher metal feedrates will result in higher metals emissions even
though particulate matter capture efficiency remains constant).
Consequently, we conclude that semi-volatile metals and low volatile
metals standards are appropriate in addition to the particulate matter
standard.
Finally, several commenters suggest that a particulate matter
standard is not needed to control the five nonenumerated metals because
the standards for the enumerated semivolatile and low volatile metals
would serve as surrogates for those
[[Page 52847]]
metals. Their rationale is that because the nonenumerated metals can be
classified as either semivolatile or nonvolatile 42, they
would be controlled along with the enumerated semivolatile and low
volatile metals. However, MACT control would not be assured for the
five nonenumerated metals even though they would be controlled by the
same emission control device as the enumerated semivolatile and low
volatile metals. For example, a source with high particulate matter
emissions could achieve the semivolatile and low volatile metal
emission standards (i.e., MACT control) by feeding low levels of
enumerated semivolatile and low volatile metals. But, if that source
also fed high levels of nonenumerated metals, MACT control for those
metals would not be achieved unless the source was subject to a
particulate matter MACT standard. Consequently, we do not agree that
the semivolatile and low volatile metal standards alone can serve as
surrogates for the nonenumerated metals.
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\42\ As a factual matter, selenium can be classified as a
semivolatile metal and the remaining four nonenumerated metals can
be classified as low volatile metals.
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We also proposed to use particulate matter as a supplemental
control for nondioxin/furan organic hazardous air pollutants that are
adsorbed onto the particulate matter. Commenters state, however, that
the Agency had not presented data showing that particulate matter in
fact contains significant levels of adsorbed nondioxin/furan organic
hazardous air pollutants. We now concur with commenters that, for
cement kiln and lightweight aggregate kiln particulate matter,
particulate matter emissions have not been shown to contain significant
levels of adsorbed organic compounds. This is likely because cement
kiln and lightweight aggregate kiln particulate matter is primarily
inert process dust (i.e., entrained raw material). Although particulate
matter emissions from incinerators could contain higher levels of
carbon that may adsorb some organic compounds, this is not likely a
significant means of control for those organic hazardous air
pollutants.43
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\43\ We recognize that sorbent (e.g., activated carbon) may be
injected into the combustion system to control mercury or dioxin/
furan. In these cases, particulate matter would be controlled as a
site-specific compliance parameter for these organics. See the
discussion in Part Five of this preamble.
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B. How Are Toxic Organic Compounds Regulated by This Rule?
1. Dioxins/Furans
We proposed that dioxin/furan emissions be controlled directly with
a dioxin/furan emission standard based on toxicity equivalents. The
final rule adopts a TEQ approach for dioxin/furans. In terms of a
source determining compliance, we expect sources to use accepted TEQ
references.44
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\44\ For example, USEPA, ``Interim Procedure for Estimating
Risks Associated With Exposures to Mixtures of Chlorinated Dibenzo-
p-Dioxin and -Dibenzofurans (CDDs and CDFs) and 1989 Update'', March
1989; Van den Berg, M., et al. ``Toxic Equivalency Factors (TEFs)
for PCBs, PCDDs, PCDFs for Humans and Wildlife'' Environmental
Health Perspectives, Volume 106, Number 12, December 1998.
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2. Carbon Monoxide and Hydrocarbons
We proposed that emissions of nondioxin/furan organic hazardous air
pollutants be controlled by compliance with continuously monitored
emission standards for either of two surrogates: carbon monoxide or
hydrocarbons. Carbon monoxide and hydrocarbons are widely accepted
indicators of combustion conditions. The current RCRA regulations for
hazardous waste combustors use emissions limits on carbon monoxide and
hydrocarbons to control emissions of nondioxin/furan toxic organic
emissions. See 56 FR 7150 (February 21, 1991) documenting the
relationship between carbon monoxide, combustion efficiency, and
emissions of organic compounds. In addition, Clean Air Act emission
standards for municipal waste combustors and medical waste incinerators
limit emissions of carbon monoxide to control nondioxin/furan organic
hazardous air pollutants. Finally, hydrocarbon emissions are an
indicator of organic hazardous air pollutants because hydrocarbons are
a direct measure of organic compounds.
Nonetheless, many commenters state that EPA's own surrogate
evaluation 45 did not demonstrate a relationship between
carbon monoxide or hydrocarbons and nondioxin/furan organic hazardous
air pollutants at the carbon monoxide and hydrocarbon levels evaluated.
Several commenters note that this should not have been a surprise given
that the carbon monoxide and hydrocarbon emissions data evaluated were
generally from hazardous waste combustors operating under good
combustion conditions (and thus, relatively low carbon monoxide and
hydrocarbon levels). Under these conditions, emissions of nondioxin/
furan organic hazardous air pollutants were generally low, which made
the demonstration of a relationship more difficult. These commenters
note that there may be a correlation between carbon monoxide and
hydrocarbons and nondioxin/furan organic hazardous air pollutants, but
it would be evident primarily when actual carbon monoxide and
hydrocarbon levels are higher than the regulatory levels. We agree, and
conclude that carbon monoxide and hydrocarbon levels higher than those
we establish as emission standards are indicative of poor combustion
conditions and the potential for increased emissions of nondioxin/furan
organic hazardous air pollutants. Consequently, we have adopted our
proposed approach for today's final rule.46
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\45\ See Energy and Environmental Research Corporation,
``Surrogate Evaluation of Thermal Treatment Systems,'' Draft Report,
October 17, 1994.
\46\ As discussed at proposal, however, this relationship does
not hold for certain types of cement kilns where carbon monoxide and
hydrocarbons emissions evolve from raw materials. See discussion in
Section VII of Part Four.
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3. Destruction and Removal Efficiency
We have determined that a destruction and removal efficiency (DRE)
standard is needed to ensure MACT control of nondioxin/furan organic
hazardous air pollutants.47 We adopt the implementation
procedures from the current RCRA requirements for DRE (see
Secs. 264.342, 264.343, and 266.104) in today's final rule. The
rationale for adopting destruction and removal efficiency as a MACT
standard is discussed later in Section IV of the preamble.
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\47\ Under this standard, several difficult to combust organic
compounds would be identified and destroyed or removed by the
combustor to at least a 99.99% (or 99.9999%, as applicable)
efficiency.
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C. How Are Hydrochloric Acid and Chlorine Gas Regulated by This Rule?
We proposed that hydrochloric acid and chlorine gas emissions be
controlled by a combined total chlorine MACT standard because: (1) The
test method used to determine hydrochloric acid and chlorine gas
emissions may not be able to distinguish between the compounds in all
situations; 48 and (2) both of these hazardous air
pollutants can be controlled by limiting feedrate of chlorine in
hazardous waste and wet scrubbing. We have adopted this approach in
today's final rule.
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\48\ See the proposed rule, 61 FR at 17376.
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One commenter questions whether it is appropriate to establish a
combined standard for hydrochloric acid and chlorine gas because the
removal efficiency of emission control equipment is substantially
different for the two pollutants. Although we agree that the efficiency
of emission control equipment is substantially different for the two
pollutants, we conclude that the MACT control techniques will readily
[[Page 52848]]
enable sources to achieve the hydrochloric acid/chlorine gas emission
standard. As discussed in Sections VI, VII, and VIII below, MACT
control for all hazardous waste combustors is control of the hazardous
waste chlorine feedrate. This control technique is equally effective
for hydrochloric acid and chlorine gas and represents MACT control for
cement kilns. MACT control for incinerators also includes wet
scrubbing. Although wet scrubbing is more efficient for controlling
hydrochloric acid, it also provides some control of chlorine gas. MACT
control for lightweight aggregate kilns also includes wet or dry
scrubbing. Although dry scrubbing does not control chlorine gas,
chlorine feedrate control combined with dry scrubbing to remove
hydrochloric acid will enable lightweight aggregate kilns to achieve
the emission standard for hydrochloric acid/chlorine gas.
III. How Are the Standards Formatted in This Rule?
A. What Are the Units of the Standards?
With one exception, the final rule expresses the emission standards
on a concentration basis as proposed, with all standards expressed as
mass per dry standard cubic meter (e.g., g/dscm), with
hydrochloric acid/chlorine gas, carbon monoxide, and hydrocarbon
standards being expressed at parts per million by volume (ppmv). The
exception is the particulate matter standard for hazardous waste
burning cement kilns where the standard is expressed as kilograms of
particulate matter per Mg of dry feed to the kiln.
Several commenters suggest that the standards should be expressed
on a mass emission basis (e.g., mg/hour) because of equity concerns
across source categories and environmental loading concerns. They are
concerned that expressing the standards on a concentration basis allows
large gas flow rate sources such as cement kilns to emit a much greater
mass of hazardous air pollutants per unit time than smaller sources
such as some on-site incinerators. Concomitantly, small sources would
incur a higher cost/lb of pollutant removed, they contend, than a large
source.49 Further, they reason that the larger sources would
pose a much greater risk to human health and the environment because
risk is a function of mass emissions of pollutants per unit of time.
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\49\ This result is not evident given that the cost of an
emission control device is generally directly proportional to the
gas flow rate, not the mass emission rate of pollutants per unit
time.
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Although we agree with commenters' point about differential
environmental loadings attributable to small versus large sources with
a concentration-based standard, we note that the mass-based standard
urged here is inherently incompatible with technology-based MACT
standards for several reasons.50 A mass-based standard does
not ensure MACT control at small sources. Small sources have lower flow
rates and thus would be allowed to emit hazardous air pollutants at
high concentrations. They could meet the standard with no or minimal
control. In addition, this inequity between small and large sources
would create an incentive to divert hazardous waste from large sources
to small sources (existing and new), causing an increase in emissions
nationally.
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\50\ Although the particulate matter standard for hazardous
waste burning cement kilns in today's rule is the New Source
Performance Standard expressed as on a mass basis (i.e., kg of
particulate matter per megagram of dry feed to the kiln), this
standard is not based on a ``mass of particulate matter emissions
per unit of time'' that commenters suggest. Rather, the cement kiln
standard can be equated to a concentration basis given that cement
kilns emit a given quantity of combustion gas per unit of dry feed
to the kiln. In fact, we proposed the cement kiln particulate matter
standard on a concentration basis, 0.03 gr/dscf, that was calculated
from the New Source Performance Standard when applied to a typical
wet process cement kiln.
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B. Why Are the Standards Corrected for Oxygen and Temperature?
As proposed, the final standards are corrected to 7 percent oxygen
and 20 deg.C because the data we use to establish the standards are
corrected in this manner and because the current RCRA regulations for
these sources require this correction. These corrections normalize the
emissions data to a common base, recognizing the variation among the
different combustors and modes of operation.
Several commenters note that the proposed oxygen correction
equation does not appropriately address hazardous waste combustors that
use oxygen enrichment systems. They recommend that the Agency
promulgate the oxygen correction factor equation proposed in 1990 for
RCRA hazardous waste incinerators. See 55 FR at 17918 (April 27, 1990).
We concur, and adopt the revised oxygen correction factor equation.
C. How Does the Rule Treat Significant Figures and Rounding?
As proposed, the final rule establishes standards and limits based
on two significant figures. One commenter notes that a minimum of three
significant figures must be used for all intermediate calculations when
rounding the results to two significant figures. We concur. Sources
should use standard procedures, such as ASTM procedure E-29-90, to
round final emission levels to two significant figures.
IV. How Are Nondioxin/Furan Organic Hazardous Air Pollutants
Controlled?
Nondioxin/furan organic hazardous air pollutants are controlled by
a destruction and removal efficiency (DRE) standard and the carbon
monoxide and hydrocarbon standards. Previous DRE tests demonstrating
compliance with the 99.99% requirement under current RCRA regulations
may be used to document compliance with the DRE standard provided that
operations have not been changed in a way that could reasonably be
expected to affect ability to meet the standard. However, if waste is
fed at a point other than the flame zone, then compliance with the
99.99% DRE standard must be demonstrated during each comprehensive
performance test, and new operating parameter limits must be
established to ensure that DRE is maintained. A 99.9999% DRE is
required for those hazardous waste combustors burning dioxin-listed
wastes. These requirements are discussed in Section IV.A. below.
In addition, the rule establishes carbon monoxide and hydrocarbons
emission standards as surrogates to ensure good combustion and control
of nondioxin/furan organic hazardous air pollutants. Continuous
monitoring and compliance with either the carbon monoxide or
hydrocarbon emissions standard is required. If you choose to
continuously monitor and comply with the carbon monoxide standard, you
must also demonstrate during the comprehensive performance test
compliance with the hydrocarbon emission standard. Additionally, you
must also set operating limits on key parameters that affect combustion
conditions to ensure continued compliance with the hydrocarbon emission
standard. Alternatively, continuous monitoring and compliance with the
hydrocarbon emissions standard eliminates the need to monitor carbon
monoxide emissions because hydrocarbon emissions are a more direct
surrogate of nondioxin/furan organic hazardous air pollutant emissions.
These requirements are discussed in Section IV.B below.
A. What Is the Rationale for DRE as a MACT Standard?
All sources must demonstrate the ability to destroy or remove 99.99
[[Page 52849]]
percent of selected principal organic hazardous compounds in the waste
feed as a MACT standard. This requirement, commonly referred to as
four-nines DRE, is a current RCRA requirement. We are promulgating the
DRE requirement as a MACT floor standard to control the emissions of
nondioxin organic hazardous air pollutants. The rule also requires
sources to establish limits on specified operating parameters to ensure
compliance with the DRE standard. See Part Five Section VII(B).
In the April 1996 NPRM, we proposed that the four-nines DRE test
requirement be retained under RCRA and be performed as part of a RCRA
approved trial burn because we did not believe that the DRE test could
be adequately implemented using the generally self-implementing MACT
performance test and notification process.51 See 61 FR
17447.
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\51\ Historically, under RCRA regulations, the permittiing
authority and hazardous waste combustion source found it necessary
to go through lengthy negotiations to develop a RCRA trial burn plan
that adequately demonstrates the unit's ability to achieve four-
nines DRE.
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In response to the April proposal, however, we received comments
that suggest the MACT comprehensive performance test and RCRA DRE trial
burn could and should be combined, and that we should combine all stack
air emission requirements for hazardous waste combustors into a single
permit. Commenters are concerned that our proposed approach required
sources to obtain two permits for air emissions and potentially be
unnecessarily subject to dual enforcement.
We investigated approaches that would achieve the goals of a single
air emission permit and inclusion of DRE in MACT. We determined that
the 40 CFR part 63 general provisions, applicable to all MACT regulated
sources unless superseded, includes a process similar to the process to
develop a RCRA trial burn test plan and allows permitting authorities
to review and approve MACT performance test plans. See 40 CFR 63.7.
Additionally, we determined that, because all hazardous waste
combustors are currently required to achieve four-nines DRE, the DRE
requirement could be included as a MACT floor standard rather than a
RCRA requirement. In the May 1997 NODA, we discussed an alternative
approach that used a modified form of the general provision's
performance test plan and approval process. The approach would allow
combination of the DRE test with the comprehensive performance test
and, therefore, facilitate implementation of DRE as a MACT standard. We
also discussed modifying the general approach to extend the performance
test plan review period to one year in advance of the date a source
plans to perform the comprehensive performance test. This extended
review period would provide sufficient time for negotiations between
permitting authorities and sources to develop and approve comprehensive
performance test plans. These test plans would identify operating
parameter limits necessary to ensure compliance with all the proposed
MACT standards, as well as, implement the four-nines DRE test as a MACT
floor standard. See 62 FR at 24241. Commenters support the process to
combine the applicable stack emission requirements into a single
permit. As for making the DRE test a MACT standard, we received no
negative comments. Many commenters, however, question the need for
subsequent DRE testing once a unit demonstrates four-nines DRE. See
discussion and our response in Subsection 2 below.
We believe that requiring the DRE test as a MACT standard is
appropriate. As we previously noted, the four-nines DRE is firmly
grounded statutory and regulatory requirement that has proven to be an
effective method to determine appropriate process controls necessary
for the combustion of hazardous waste. Specifically, RCRA requires that
all hazardous waste incinerators must demonstrate the minimum
technology requirement of four-nines DRE (RCRA section 3004(o)(1)(B)).
Additionally, the current RCRA BIF regulations require that all boiler
and industrial furnaces meet the four-nines DRE standard. Moreover,
current RCRA regulations require all sources incinerating certain
dioxin-listed contaminated wastes (F020-023 and F026-27) to achieve
99.9999% (six-nines) DRE. See Secs. 264.343(a)(2) and 266.104(a)(3).
The statutory requirement for incinerators to meet four-nines DRE
can be satisfied if the associated MACT requirements ensure that
incinerators will continue to meet the four-nines DRE minimum
technology requirement, i.e., that MACT standards provide at least the
``minimum'' RCRA section 3004(o)(1) level of control. To determine if
the RCRA statutory requirements could be satisfied, we investigated
whether DRE could be replaced with universal standards for key
operating parameters based on previous DRE demonstrations (i.e.,
standards for carbon monoxide and hydrocarbon emissions). We found
that, in the vast majority of DRE test conditions, if a unit operated
with carbon monoxide levels of less than 100 ppmv and hydrocarbon
emissions of less than 10 ppmv, the unit met or surpassed four-nines
DRE. In a small number of test conditions, units emitted carbon
monoxide and hydrocarbons at levels less than 100 and 10 ppmv
respectively, but failed to meet four-nines DRE. Most failed test
conditions were either due to questionable test results or faulty test
design.52 See U.S. EPA, ``Draft Technical Support Document
for HWC MACT Standards (NODA), Volume II: Evaluation of CO/HC and DRE
Database,'' April 1997. Even though we could potentially explain the
reasons these units failed to achieve four-nines DRE, we determined
that universal carbon monoxide and hydrocarbon emissions limits may not
ensure that all units achieve four-nines DRE because carbon monoxide
and hydrocarbon emissions may not be representative of good combustion
for all operating conditions that facilities may desire to operate. In
addition, we could not identify a better method than the DRE test to
limit combustion failures modes.
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\52\ In many of the failed test conditions that we investigated,
the facility fed a low concentration of organic compound on which
the DRE was being calculated. As has been observed many times,
organic compounds can be reformed in the post combustion gas stream
at concentrations sufficient to fail DRE. This is not indicative of
a failure in the systems ability to destroy the compound, but is
more likely the result of a poorly designed test. If the facility
had fed a higher concentration of organic compound in the waste to
the combustor, the unit would have been more likely to meet four-
nines DRE with no change in the operating conditions used during the
test. In other cases, poor test design (i.e., firing aqueous organic
waste into an unfired secondary combustion chamber) is considered to
be the cause.
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Commenters state that the test conditions under which the DRE
failures occurred involved feeding practices that were not common in
the hazardous waste combustion industry. They further state that, if it
could be ensured that hazardous waste ignited, hydrocarbon and carbon
monoxide limits would be sufficient to ensure four-nines DRE is
achieved continuously. Therefore, a DRE demonstration would not be
warranted. Although we might agree in theory, the fact that tests were
performed under these test conditions indicates that a source desired
to operate in that fashion. Only the DRE test identified that the
combustion failure occurred and was not susceptible to control via
carbon monoxide and hydrocarbon emissions. This and other similar
failures can lead to increased emissions of products of incomplete
combustion and organic hazardous air pollutants. Also, as commenters
acknowledge, carbon monoxide and hydrocarbon emissions were effective
surrogates to ensure four-nines DRE only when
[[Page 52850]]
hazardous waste ignited. However, as we identified in the May 1997
NODA, there are a number of hazardous waste combustion sources that
operate in a manner that does not ensure ignition of hazardous waste.
As a result of the DRE test investigation, we determined that a
successful DRE demonstration is an effective, appropriate, and
necessary method to identify operating parameter limits that ensure
proper and achievable combustion of hazardous waste and to limit the
emissions of organic hazardous air pollutants. Additionally, the DRE
standard is a direct measure to ensure that the RCRA section 3004(o)(1)
mandate and its protectiveness goals are being met, and also serves to
maintain a consistent test protocol for sources combusting hazardous
waste. The DRE demonstration requirement is also reasonable, provides a
sound means to allow deferral of a RCRA mandate to the CAA, and
simplifies implementation by having all stack emissions-related testing
and compliance requirements promulgated under one statute, the CAA.
Therefore, we retain the DRE demonstration as part of the MACT
comprehensive performance test unless a DRE test has already been
performed with no relevant changes.
1. MACT DRE Standard
In today's rule, all affected sources are required to meet 99.99%
DRE of selected Principal Organic Hazardous Constituents (POCs) that
are as or more difficult to destroy than any organic hazardous
pollutant fed to the unit. With one exception discussed in subsection 3
below, this demonstration need be made only once during the operational
life of a source, either before or during the initial comprehensive
performance test, provided that the design, operation, and maintenance
features do not change in a manner that could reasonably be expected to
affect the ability to meet the DRE standard.
The DRE demonstration involves feeding a known mass of POHC(s) to a
combustion unit, and then measuring for that POHC(s) in stack
emissions. If the POHC(s) is emitted at a level that exceeds 0.01% of
the mass of the individual POHC(s) fed to the unit, the unit fails to
demonstrate sufficient DRE.
Operating limits for key combustion parameters are used to ensure
four-nines DRE is maintained. The operating parameter limits are
established based on operations during the DRE test. Examples of
combustion parameters that are used to set operating limits include
minimum combustion chamber temperature, minimum gas residence time, and
maximum hazardous waste feedrate by mass. See Sec. 63.1209(j).
Today's MACT DRE requirement is essentially the same as that
currently required under RCRA. The main difference is that the vast
majority of the MACT DRE demonstrations would not have to be repeated
as often as currently required under RCRA, as discussed in section 3
below.
2. How Can Previous Successful Demonstrations of DRE Be Used To
Demonstrate Compliance?
Except as discussed below, today's rule requires that, at least
once during the operational life of a source during or before the
initial comprehensive performance test, the source must demonstrate the
ability to achieve 99.99% DRE and must set operating parameter limits
to ensure that DRE is maintained. However, we recognize that many
sources have already undergone approved DRE testing. Further, many
facilities do not intend to modify their units design or operations in
such a way that DRE performance or parameters would be adversely
affected. Therefore, the Agency is allowing sources to use results from
previous EPA or State-approved DRE demonstrations to fulfill the MACT
four-nines DRE requirement, as well as to set the necessary operating
limits on parameters that ensure continued compliance.
If a facility wishes to operate under new operating parameter
limits that could reasonably be expected to affect the ability to meet
the standard, a new DRE demonstration must be performed before or
concurrent with the comprehensive performance test. If the DRE
operating limits conflict with operating parameter limits that are set
to ensure compliance with other MACT standards, the unit must comply
with the more stringent limits. Additionally, if a source is modified
in such a way that its DRE operating limits are no longer applicable or
valid, the source must perform a new DRE test. Moreover, if a source is
modified in any way such that DRE performance or parameters are
affected adversely, the source must perform a new DRE test.
3. DRE for Sources That Feed Waste at Locations Other Than the Flame
Zone
Today's rule requires sources that feed hazardous waste in
locations other than the flame zone to perform periodic DRE tests to
ensure that four-nines DRE continues to be achieved over the life of
the unit. As indicated in the May 1997 NODA at 62 FR 25877, the Agency
is concerned that these types of sources have a greater potential of
varying DRE performance due to their waste firing practices. That is,
due to the unique design and operation of the waste firing system, the
DRE may vary over time, and those variations cannot be identified or
limited through operating limits set during a single DRE test. For
these units, we are requiring that DRE be verified during each
comprehensive performance test and that new operating parameter limits
be established to ensure continued compliance.
4. Sources That Feed Dioxin Wastes
In today's rule, we are requiring all sources that feed certain
dioxin-listed wastes (i.e., F020-F023, F026, F027) to demonstrate the
ability to achieve 99.9999 percent (six-nines) DRE as a MACT standard.
This requirement will serve to achieve a number of goals associated
with today's regulations. First, under RCRA, six-nines DRE is required
when burning certain dioxin-listed wastes. If we did not promulgate
this requirement as a MACT standard, sources that feed dioxin-listed
waste would be required to maintain two permits to manage their air
emissions. Thus, by including this requirement as a MACT standard, we
eliminate any unnecessary duplication. That outcome is contrary to our
goal which is to limit, to the greatest extent possible, the need for
sources to obtain two permits governing air emissions under different
statutory authorities. Second, six-nines DRE helps to improve control
of nondioxin organic hazardous air pollutants as well. Finally, this
requirement properly reflects floor control for sources that feed
dioxin-listed wastes. Currently, all sources that feed dioxin listed
wastes must achieve six-nines DRE. Before making the decision to
include six-nines DRE as a MACT standard, we considered whether the
requirements could be eliminated given that we are issuing dioxin/furan
emission standards with today's rule. We concluded, first, that we had
not provided sufficient notice and comment to depart from the current
regulations applicable to these sources. Second, we also decided that
because we currently require other similar highly toxic bioaccumulative
and persistent compounds (e.g., PCB wastes) to be fed to units that
demonstrate six-nines DRE, a departure from that policy for RCRA dioxin
wastes would be inconsistent. Finally, we are in discussions that may
cause us to reevaluate our overall approach to dioxin-listed wastes,
with the potential to impact this rule and the land disposal
restrictions program. Any changes to our approach will be included in a
single rulemaking that would be proposed later.
[[Page 52851]]
B. What Is the Rationale for Carbon Monoxide or Hydrocarbon Standards
as Surrogate Control of Organic Hazardous Air Pollutants?
Today's rule adopts limits on emissions of carbon monoxide and
hydrocarbons as surrogates to ensure good combustion and control of
nondioxin organic hazardous air pollutants. We require continuous
emissions monitoring and compliance with either the carbon monoxide or
hydrocarbon emissions standard. Sources can choose which of these two
standards it wishes to continuously monitor for compliance. If a source
chooses the carbon monoxide standard, it must also demonstrate during
the comprehensive performance test compliance with the hydrocarbon
emission standard. During this test the source also must set operating
limits on key parameters that affect combustion conditions to ensure
continued compliance with the hydrocarbon emission standard. These
parameters relate to good combustion practices and are identical to
those for which you must establish limits under the DRE standard. See
Sec. 63.109(a)(7) and 63.1209(j). However, this source need not install
and use a continuous hydrocarbon monitor to ensure continued compliance
with the hydrocarbon standard. As discussed previously, the limits
established for DRE are identical. If a source elects to use the
hydrocarbon limit for compliance, then it must continuously monitor and
comply with the hydrocarbon emissions standard. However, this type of
source need not monitor carbon monoxide emissions or carbon monoxide
operating parameters because hydrocarbon emissions are a more direct
surrogate of nondioxin organic hazardous air pollutant emissions.
The April 1996 NPRM proposed MACT emission standards for both
carbon monoxide and hydrocarbon as surrogates to control emissions of
nondioxin organic hazardous air pollutants. We also proposed that
cement kilns comply with either a carbon monoxide or hydrocarbons
standard due to raw material considerations.53 See 61 FR at
17375-6. Our reliance on only carbon monoxide or only hydrocarbon has
drawbacks, and therefore we proposed that incinerators and lightweight
aggregate kilns comply with emissions standards for both. Nonetheless,
we also acknowledged that requiring compliance with both carbon
monoxide and hydrocarbon standards may be redundant, and requested
comment on: (1) Giving sources the option of complying with either
carbon monoxide or hydrocarbon emission standards; or (2) establishing
a MACT standard for either carbon monoxide or hydrocarbon, but not
both.
---------------------------------------------------------------------------
\53\ See discussion regarding cement kilns compliance with the
carbon monoxide and/or hydrocarbon standards in Part Four, Section
VII.D.
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Comments to our proposed approach question the necessity of two
related surrogates to control organic hazardous air pollutants. Many
commenters assert they are capable of controlling hydrocarbon emissions
effectively, but due to their system's unique design, they could not
comply continuously with the carbon monoxide emission standard. In
general, commenters prefer an approach that would afford them maximum
flexibility in demonstrating compliance with organic control standards,
i.e., more like option (1) in the NPRM.
The May 1997 NODA included a refined version of the option that
commenters prefer that allowed sources to monitor and comply with
either a carbon monoxide or hydrocarbon emission standard. In response
to the May 1997 NODA, commenters nearly unanimously support the option
that allowed facilities to monitor and comply with either the carbon
monoxide or hydrocarbon standard as surrogates to limit emissions of
nondioxin organic hazardous air pollutants. However, a few commenters
suggest that compliance with carbon monoxide or hydrocarbons in
combination with DRE testing is redundant and unnecessary. However, in
their comments, they do not address the issue of DRE failures
associated with low carbon monoxide or hydrocarbon emissions, other
than to state that if ignition failure was avoided, emissions of carbon
monoxide or hydrocarbons would be good indicators of combustion
efficiency and four-nines DRE. This does not address our concerns,
which reflect cases in which ignition failures did not occur and in
which destruction and removal efficiencies were not met.
In the May 1997 NODA, we discussed another option that required
sources to comply with the hydrocarbon emission standard and establish
a site-specific carbon monoxide limit higher than 100 ppmv. This option
was developed because compliance with the hydrocarbon standard assures
control of nondioxin organic hazardous air pollutants, and a site-
specific carbon monoxide limit aids compliance by providing advanced
information regarding combustion efficiency. However, we conclude that
this option may be best applied as a site-specific remedy in situations
where a source has trouble maintaining compliance with the hydrocarbon
standard.
Today's final rule modifies the May 1997 NODA approach slightly.
Complying with the carbon monoxide standard now requires documentation
that hydrocarbon emissions during the performance test are lower than
the standard, and requires operating limits on parameters that affect
hydrocarbon emissions. We adopt this modification because some data
show that high hydrocarbon emissions are possible while simultaneously
low carbon monoxide emissions are found.54
---------------------------------------------------------------------------
\54\ In a number of instances, RCRA compliance test records
showed that sources emitting carbon monoxide at less than 100 ppmv
emitted hydrocarbons in excess of 10 ppmv.
---------------------------------------------------------------------------
In the BIF rule (56 FR at 7149-50), we found that both monitoring
and compliance with either carbon monoxide or hydrocarbon limits and
achieving four-nines DRE is needed to ensure control of products of
incomplete combustion (including nondioxin organic hazardous air
pollutants) that are a result of hazardous waste combustion. DRE,
although sensitive to identifying combustion failure modes, cannot
independently ensure that emissions of products of incomplete
combustion or organic hazardous air pollutants are being controlled.
DRE can only provide the assurance that, if a hazardous waste combustor
is operating normally, the source has the capability to transform
hazardous and toxic organic compounds into different compounds through
oxidation. These other compounds can include carbon dioxide, water, and
other organic hazardous air pollutants. Because carbon monoxide
provides immediate information regarding combustion efficiency
potentially leading to emissions of organic hazardous air pollutants
and hydrocarbon provides a direct measure of organic emissions, these
two parameters individually or in combination provide additional
control that would not be realized with the DRE operating parameter
limits alone.55 Neither our data nor data supplied by
commenters show that only monitoring
[[Page 52852]]
carbon monoxide, hydrocarbons, or DRE by itself can adequately ensure
control of nondioxin organics. Therefore, the approach used in the BIF
rule still provides the best regulatory model. We conclude in today's
rule that hydrocarbons and carbon monoxide monitoring are not redundant
with the DRE testing requirement to control emissions of organic
hazardous air pollutants and require both standards. For an additional
discussion regarding the use of hydrocarbons and carbon monoxide to
control emissions of organic hazardous air pollutants, see USEPA,
``Technical Support Document for HWC MACT Standards, Volume III:
Selection of MACT Standards and Technologies,'' July 1999.
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\55\ We acknowledge that although hydrocarbon emissions are a
direct measure of organic emissions, they are measured with a
continuous emissions monitoring system known as a flame ionization
detector. Some data suggest hydrocarbon flame ionization detectors
do not respond with the same sensitivity to the full spectrum of
organic compounds that may be present in the combustion gas.
Additionally, combustion gas conditions also may affect the
sensitivity and accuracy of the monitor. Nonetheless, monitoring
hydrocarbons with these detectors appears to be the best method
reasonably available to provide real-time monitoring of organic
emissions from a hazardous waste combustor.
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V. What Methodology Is Used To Identify MACT Floors?
This section discusses: (1) Methods used to identify MACT floor
controls and emission levels for the final rule; (2) the rationale for
using hazardous waste feedrate control as part of MACT floor control
for the metals and total chlorine standards; (3) alternative methods
for establishing floor levels considered at proposal and in the May
1997 NODA; and (4) our consideration of emissions variability in
identifying MACT floor levels.
A. What Is the CAA Statutory Requirement To Identify MACT Floors?
We identify hazardous waste incinerators, hazardous waste burning
cement kilns, and hazardous waste burning lightweight aggregate kilns
as source categories to be regulated under section 112. We must,
therefore, develop MACT standards for each category to control
emissions of hazardous air pollutants. Under CAA section 112, we may
distinguish among classes, types and sizes of sources within a category
in establishing such standards.
Section 112 prescribes a minimum baseline or ``floor'' for
standards. For new sources, the standards for a source category cannot
be less stringent than the emission control that is achieved in
practice by the best-controlled similar source. Section 112(d)(3). The
standards for existing sources may be less stringent than standards for
new sources, but cannot be less stringent than ``(A) * * * the average
emissions limitation achieved by the best performing 12 percent of the
existing sources (for which the Administrator has emissions
information) * * *, in the category or subcategory for categories and
subcategories with 30 or more sources, or (B) the average emissions
limitation achieved by the best performing 5 sources (for which the
Administrator has or could reasonably obtain emissions information) in
the category or subcategory for categories and subcategories with fewer
than 30 sources.'' Id.
We also must consider a more stringent standard than the floor,
referred to in today's rule as a ``beyond-the-floor'' standard. For
each beyond-the-floor analysis, we evaluate the maximum degree in
reduction of hazardous air pollutants determined to be achievable,
taking into account the cost of achieving those reductions, nonair
quality health and environmental impacts, and energy costs. Section
112(d)(2). The object of a beyond-the-floor standard is to achieve the
maximum degree of emission reduction without unreasonable economic,
energy, or secondary environmental impacts.
B. What Is the Final Rule Floor Methodology?
Today's rule establishes MACT standards for the following hazardous
air pollutants, hazardous air pollutant groups or hazardous air
pollutant surrogates: dioxin/furans, mercury, two semivolatile metals
(lead and cadmium), three low volatile metals (arsenic, beryllium, and
chromium), particulate matter, total chlorine (hydrochloric acid and
chlorine gas), carbon monoxide, hydrocarbons, and destruction and
removal efficiency. This subsection discusses the overall engineering
evaluation and data analysis methods we used to establish MACT floors
for these standards. Additional detail on the specific application of
these methods for each source category and standard is presented in
Part Four, Sections VI-VIII, of the preamble and in the technical
support document.56
---------------------------------------------------------------------------
\56\ USEPA, ``Final Technical Support Document for HWC MACT
Standards, Volume III: Selection of MACT Standards and
Technologies,'' July 1999.
---------------------------------------------------------------------------
1. What Is the General Approach Used in This Final Rule?
The starting point in developing standards is to determine a MACT
floor emission level, the most lenient level at which a standard can be
set. To identify the floor level, we first identified the control
techniques used by the best performing sources. We designate these best
performing sources the ``MACT pool'' and the emission control
technologies they use we call ``MACT floor controls.''
After identifying the MACT pool and MACT floor controls, we
determine the emission level that the MACT floor controls are routinely
achieving--that is, an achievable emission level taking into account
normal operating variability (i.e., variability inherent in a properly
designed and operated control system). This is called the floor
emission level. To ensure that the floor emission level is being
achieved by all sources using floor controls (i.e., not just the MACT
pool sources), we generally consider emissions data from all sources in
a source category that use well-designed and properly operated MACT
floor controls. (We call the data set of all sources using floor
controls the ``expanded MACT pool.'') Floor levels in this rule are
generally established as the level achieved by the source in the
expanded MACT pool with the highest emissions average 57
using well-designed and properly operated MACT floor controls.
---------------------------------------------------------------------------
\57\ Each source's emissions usually are expressed as an average
of three or more emission measurements at the same set of operating
parameters. This is because compliance is based on the average of
three or more runs.
---------------------------------------------------------------------------
Several commenters oppose considering emissions data from all
sources using MACT floor controls (i.e., the expanded MACT pool)
because they assert the expansion of the MACT pool results in inflated
floors. If we adopt these commenters' recommendation, then many sources
using MACT controls would not meet the standard, even though they were
using MACT floor control. (Indeed, in some cases, other test conditions
from the very system used to establish the MACT pool would not meet the
standard, notwithstanding no significant change in the system's design
and operation.) This result is inappropriate in that all sources using
properly designed and operated MACT floor controls should achieve the
floor emission level if the technology is well designed and operated.
In the absence of data indicating a design or operation problem, we
assume the floor emission level based on an expanded MACT pool reflects
an emission level consistently achievable by MACT floor technology. Our
resulting limits account for the fact that sources and emissions
controls will experience normal operating variability even when
properly designed and operated.
The MACT floor methodology in this rule does not use a single
uniform data analysis approach consistently across all three source
categories and standards. Our data analysis methods vary due to: (1)
Limitations of our emissions data and ancillary information; (2)
emissions of some hazardous air pollutants being related to the
feedrate of the hazardous air pollutant (e.g., semivolatile metal
emissions are affected by semivolatile metal feedrates) while emissions
of
[[Page 52853]]
other hazardous air pollutants are not (e.g., dioxin/furan emissions
are related to postcombustion dioxin/furan formation rather than
dioxin/furan feedrates); (3) the various types of emissions controls
currently in use which do not lend themselves to one type of MACT
analysis; and (4) consideration of existing regulations as themselves
establishing floor levels.
Finally, as discussed in Section D, the MACT floor levels
established through our data analysis approaches account for emissions
variability without the separate addition of a statistically-derived
emissions variability factor.
2. What MACT Floor Approach Is Used for Each Standard?
a. Dioxins and Furans. For dioxins and furans, we adopt the MACT
floor methodology discussed in the May 1997 NODA. Based on engineering
information and principles, we identify temperature of combustion gas
at the particulate matter control device of 400 deg.F or less as MACT
floor control of dioxin/furan. This technology and level of control has
been selected because postcombustion formation of dioxin/furan is
suppressed by lowering postcombustion gas temperatures, and formation
is reasonably minimized at gas temperatures of 400 deg.F or below.
Sources controlling gas temperatures to 400 deg.F or less at the
particulate matter control device represent the level achieved by the
median of the best performing 12 percent of sources where the source
category has more than 30 sources (or the median of the best performing
five sources where the source category has fewer than 30 sources).
The next step is to identify an emissions level that MACT floor
control achieved on a routine basis. We analyzed the emissions data
from all sources (within each source category) using MACT floor control
and establish the floor level equal to the highest test condition
average.
As discussed in greater detail in Part Four, Section VI,
incinerators with waste heat recovery boilers present a unique
situation for dioxin/furan control. Our data base shows that
incinerators equipped with waste heat recovery boilers have
significantly higher dioxin/furan emissions compared to other
incinerators. In the waste heat recovery boiler, combustion gas is
exposed to particles on boiler tubes within the temperature window of
450 deg. F to 650 deg. F, which promotes surface-catalyzed formation of
dioxin/furan. Therefore, we establish separate dioxin/furan standards
for incinerators with waste heat boilers and incinerators without waste
heat boilers.58 The specified floor control for both waste
heat boilers and nonwaste heat boilers is combustion gas temperature
control to 400 deg.F or less at the particulate matter control
device.59 Floor levels for waste heat boiler incinerators
are much higher, however, because of the dioxin/furan formation during
the relatively slow temperature quench in the boiler. See the
incinerator dioxin/furan discussion in Part Four, Section VI, of
today's rule for more details.
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\58\ We concluded that separate standards to control other
hazardous air pollutants were not needed for waste heat boiler-
equipped incinerators versus other incinerators. That is, whether or
not the incinerator is equipped with a waste heat recovery boiler is
only of concern for dioxin/furan emissions, not the other hazardous
air pollutants.
\59\ Wet particulate matter control devices (e.g., venturi
scrubbers) inherently preclude dioxin/furan formation because: (1)
They do not suspend particulate matter in the combustion gas flow as
do fabric filters and electrostatic precipitators, and (2) gas
temperatures are below 400 deg.F in the scrubber. Given this, floor
control is use of a wet particulate matter control device or control
of combustion gas temperature to 400 deg.F or below at the inlet to
a dry particulate matter control device.
---------------------------------------------------------------------------
b. What MACT Floor Methodology Is Used for Particulate Matter? We
adopt a final MACT floor methodology for particulate matter based on
the approaches discussed in the May 1997 NODA. For incinerators, the
final MACT floor is determined through engineering principles and
information, coupled with analysis of the emissions data base. For
cement kilns, we base final MACT on the existing requirements of the
New Source Performance Standard applicable to Portland cement kilns.
Finally, for lightweight aggregate kilns, the final floor level is
derived directly from the emissions data base (i.e., the highest test
condition average for sources using properly designed and operated
floor control).
i. Incinerators. Today's rule identifies MACT floor control as
either a well-designed, operated, and maintained fabric filter,
ionizing wet scrubber, or electrostatic precipitator, based on
engineering information and an evaluation of the particulate matter
control equipment used by at least the median of the best performing 12
percent of sources and the emission levels achieved. These types of
particulate matter control equipment routinely and consistently achieve
superior particulate matter performance relative to other controls used
by the incinerator source category and thus represent MACT. Using
generally accepted engineering information and principles, we then
identify an emission level that well-designed, operated and maintained
fabric filters, ionizing wet scrubbers, and electrostatic precipitators
routinely achieve.
The floor level is not directly identified from the emissions data
base as the highest test condition average for sources using a fabric
filter, ionizing wet scrubber, or electrostatic precipitator. The
hazardous waste combustor incinerator data base, however, was used as a
tool to determine if the identified floor level, established on
generally accepted engineering information and principles, is in
general agreement with available particulate matter data. This is
because we do not have adequate data on the features of the control
devices to accurately distinguish only those devices that are well-
designed, operated, and maintained and thus representative of MACT.
Several sources in the emissions data base that are equipped with
fabric filters, ionizing wet scrubbers, or electrostatic precipitators
have emission levels well above the emission levels of other sources
equipped with those devices. This strongly suggests that the higher
levels are not representative of those achieved by well-designed,
operated, and maintained units, even when normal operating variability
is considered. We accordingly did not use these data in establishing
the standard. See Kennecott v. EPA, 780 F.2d 445, 458 (4th Cir. 1985)
(EPA ``can reject data it reasonably believes to be unreliable
including performance data that is higher than other plants operating
the same control technology.'')
ii. Cement Kilns. As discussed in the May 1997 NODA and in more
detail in the standards section for cement kilns in Part Four, Section
VII, we base the MACT floor emission level on use of a fabric filter or
electrostatic precipitator to achieve the New Source Performance
Standard for Portland cement kilns. The MACT floor is equivalent to and
expressed as the current New Source Performance Standard of 0.15 kg/Mg
dry feed (0.30 lb/ton dry feed). In the NPRM and the May 1997 NODA, we
proposed to express the particulate matter standard on a concentration
basis. However, because we are not yet requiring sources to document
compliance with the particulate matter standard by using a particulate
matter continuous emissions monitoring system in this final rule, we
establish and express the floor emission level equivalent to the New
Source Performance Standard. Commenters' concerns about separate MACT
pools for particulate matter, semivolatile metals, and low volatile
metals are discussed in Part Four, Section VII.
iii. Lightweight Aggregate Kilns. All lightweight aggregate kilns
burning
[[Page 52854]]
hazardous waste are equipped with fabric filters. We could not
distinguish only those sources with fabric filters better designed,
operated, and maintained than others, and thus represent MACT control.
Because we could not independently use engineering information and
principles to otherwise distinguish which well-designed, operated, and
maintained fabric filters are routinely achieving levels below the
highest test condition average in the emissions data base (i.e.,
considering the high inlet grain loadings for lightweight aggregate
kilns), we establish the floor level as that highest test condition
average emission level. Commenters concerns about a high floor level
and separate MACT pools for particulate matter, semivolatile metals,
and low volatile metals are discussed in Part Four, Section VIII.
c. Metals and Total Chlorine. This rule establishes MACT standards
for mercury; semivolatile metals comprised of combined emissions of
lead and cadmium; low volatility metals comprised of combined emissions
of arsenic, beryllium, and chromium; and total chlorine comprised of
combined emissions of hydrogen chloride and chlorine gas. As shown by
the following analysis, these hazardous air pollutants are all
controlled by the best performing sources, at least in part, by
feedrate control of the metal or chlorine in the hazardous waste. In
addition to hazardous waste feedrate control, some of the hazardous air
pollutants also are controlled by air pollution control equipment. Both
semivolatile metals and low volatile metals are controlled by a
combination of hazardous waste metal feedrate control and by
particulate matter control equipment. Total chlorine is controlled by a
combination of feedrate control and, for hazardous waste incinerators,
scrubbing equipment designed to remove acid gases.
i. How Are the Metals and Chlorine Floor Control(s) Identified? We
follow the language of CAA section 112(d)(3) to identify the control
techniques used by the best performing sources. The hazardous waste
incinerator and hazardous waste cement kiln source categories are
comprised of 186 and 33 sources, respectively. From the statutory
language, we conclude that for this analysis the control techniques
used by the best performing 6% of sources represents the average of the
best performing 12% of the sources in those categories. It follows,
therefore, that floor control for metals and chlorine is the
technique(s) used by the best performing 12 incinerators and two cement
kilns.
Because the hazardous waste lightweight aggregate kiln source
category is comprised of only 10 sources, we follow the language of
section 112(d)(3)(B) to identify the control technique(s) used by the
three best performing sources, which represents the median of the best
performing five sources.
Our floor control analysis indicates that the best performing 12
incinerators, two cement kilns, and three lightweight aggregate kilns
all use hazardous waste feedrate control to limit emissions of mercury,
semivolatile metal, low volatile metal, and total chlorine. For the
semivolatile and low volatile metals, the best performing sources also
use particulate matter control as part of the floor control technique.
In addition, the best performing incinerator sources also control total
chlorine and mercury with wet scrubbing. Accordingly, we identify floor
control for semivolatile metal and low volatile metal as hazardous
waste feedrate control plus particulate matter control, and floor
control for incinerators for total chlorine and mercury as hazardous
waste feedrate control plus wet scrubbing.
ii. What is the Rationale for Using Hazardous Waste Feedrate
Control as MACT Floor Control Technique? As discussed above, MACT floor
control for mercury, semivolatile metals, low volatile metals, and
total chlorine is based on, or at least partially based on, feedrate
control of metal and chlorine in the hazardous waste. The feedrate of
metal hazardous air pollutants will affect emissions of those
pollutants, and the feedrate of chlorine will affect emissions of total
chlorine (i.e., hydrochloric acid and chlorine gas) because metals and
chlorine are elements and are not destroyed during combustion.
Emissions controls, if any, control only a percentage of the metal or
total chlorine fed. Therefore, as concentrations of metals and total
chlorine in the inlet to the control device increase, emissions
increase.
At proposal, we identified hazardous waste feedrates as part of the
technology basis for the proposed floor emission
standards.60 MACT maximum theoretical emission
concentrations 61 (MTECs) were established individually for
mercury, semivolatile metals, low volatile metals, and total chlorine
at a level equal to the highest MTEC of the average of the best
performing 12% of sources. For some hazardous air pollutants, hazardous
waste feedrate control of metals and chlorine was identified as the
sole component of floor control (i.e., where the best performing
existing sources do not use pollution control equipment to remove the
hazardous air pollutant). Examples include mercury and total chlorine
from cement kilns. For other hazardous air pollutants, we identified
hazardous waste feedrate control of metals and chlorine as a partial
component of MACT floor control (e.g., floor control for semivolatile
metals include good particulate matter control in addition to feedrate
control of semivolatile metals in hazardous waste).
---------------------------------------------------------------------------
\60\ See 61 FR at 17366.
\61\ We developed a term, Maximum Theoretical Emissions
Concentration, to compare metals and chlorine feedrates across
sources of different sizes. MTEC is defined as the metals or
chlorine feedrate divided by the gas flow rate, and is expressed in
g/dscm.
---------------------------------------------------------------------------
In the May 1997 NODA, we continued to consider hazardous waste
feedrate control of metals and chlorine as a valid floor control
technology. However, rather than defining a specific MACT control
feedrate level (expressed as a MTEC), we instead relied on another
analysis tool, an emissions breakpoint analysis, to identify sources
feeding metals and/or chlorine at high (and not MACT) levels. At the
time, we believed that the breakpoint analysis was a less problematic
approach to identify sources using MACT floor control than the
approaches proposed initially.62
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\62\ Comments had objected to our proposed approach of defining
MTECs as too reliant on engineering inspection of the data.
---------------------------------------------------------------------------
Given commenters' subsequent concerns with the emissions breakpoint
analysis as well (see discussion in Section C below), we conclude that
specifying MTECs as MACT control (partially or solely) is necessary to
properly reflect the feedrate component of MACT control.
Notwithstanding how the MACT floor MTEC is defined, many commenters
suggest that our consideration of hazardous waste feedrate as a floor
control technique is inappropriate in a technology-based rulemaking and
not permissible under the CAA. Commenters also state that hazardous
waste feedrate control is not a control technique due to the wide
variations in metals and chlorine in the hazardous waste generated at a
single facility location. Further, they believe even greater variations
occur in metals and chlorine levels in the hazardous waste generated at
multiple production sites representing different industrial sectors.
Thus, commenters suggest that basing a floor emission level on data
from sources that feed hazardous waste with low levels of metals or
chlorine is tantamount to declaring that wastes with higher levels of
metals or chlorine are not to be generated. Other
[[Page 52855]]
commenters note, however, that hazardous waste feedrate control must be
considered as a floor control technique because feedrate control is
being used as a control means to comply with existing RCRA regulations
for these combustors. Still other commenters recommend that we
establish uniform hazardous waste feedrate limits (i.e., base the
standard on an emission concentration coupled with a hazardous waste
feedrate limit on metals and chlorine) across all three hazardous waste
combustor source categories. Please refer to Part Five, Section
VII.D.3.c.iv of today's preamble and the Comment Response Document for
detailed responses to these comments.
We do not accept the argument that control of hazardous waste
metals and chlorine levels in hazardous waste cannot be part of the
floor technology. First, control of hazardous air pollutants in
hazardous waste feedstock(s) can be part of a MACT standard under
section 112(d)(2)(A), which clearly indicates that material
substitution can be part of MACT. Second, hazardous waste combustors
are presently controlling the level of metal hazardous air pollutants
and chlorine in the hazardous waste combusted because of RCRA
regulatory requirements. (See Sec. 266.103(c)(1) and (j) where metal
and chlorine feedrate controls are required, and where monitoring of
feedrates are required.) Simply because these existing controls are
risk-based, rather than technology-based, does not mean that they are
not means of controlling air emissions cognizable under the CAA. Floor
standards are to be based on ``emission limitation[s]'' achieved by the
best existing sources. An ``emission limitation'' includes ``a
requirement established by the * * * Administrator which limits the
quantity, rate, or concentration of emissions. * * * including any
requirement relating to the operation * * * of a source. * * *'' CAA
section 302(k). This is precisely what current regulations require to
control metal and chlorine levels in hazardous waste feed.
Commenters also note that contemplated floor levels were lower than
the feed limits specified in current regulations for boilers and
industrial furnaces. This is true, but not an impediment to identifying
achievable MACT floor levels. Actual performance levels can serve as a
basis for a floor. An analogy would be where a group of facilities
achieve better capture efficiency from air pollution control devices
than required by existing rule. That level of performance (if generally
achievable) can serve as the basis for a floor standard. Accordingly,
we use hazardous waste feedrate, entirely or partially, to determine
floor levels and beyond-the-floor levels for mercury, semivolatile
metals, low volatile metals, and total chlorine.
iii. How Are Feedrate and Emissions Levels Representative of MACT
Floor Control Identified? After identifying feedrate control as floor
control, we use a data analysis method called the ``aggregate feedrate
approach'' to establish floor control hazardous waste feedrate levels
and emission levels for mercury, semivolatile metals, low volatile
metals, and total chlorine. The first step in the aggregate feedrate
approach is to identify an appropriate level of aggregated mercury,
semivolatile metals, low volatile metals, and total chlorine feedrate
control, expressed as a MTEC, being achieved in practice by the best
performing incinerator, cement kiln and lightweight aggregate kiln
sources. This aggregate MTEC level is derived only from the sources
using MACT floor emission controls.
The aggregate feedrate approach involves four steps: (1)
Identifying test conditions in the data base where data are available
to calculate hazardous waste feedrate MTECs for all three metal
hazardous air pollutant groups and total chlorine; (2) screening out
test conditions where a source was not using the MACT floor emission
control device for hazardous air pollutants that are cocontrolled by an
air pollution control device 63; (3) ranking the individual
hazardous air pollutant MTECs, from the different source test
conditions, from lowest to highest and assigning each a numerical rank,
with a rank of one being the lowest MTEC; and (4) summing, for each
test condition, the individual ranking for each of the hazardous air
pollutants to determine a composite ranking. The total sum is used to
provide an overall assessment of the aggregate level of hazardous air
pollutants in the hazardous waste for each test condition. The
hazardous waste feed streams with lower total sums (i.e., hazardous air
pollutant levels) are ``cleaner'' in aggregate than those with higher
total sums.64 (See the technical support document for more
details on this procedure.65)
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\63\ For example, to potentially be considered a MACT-controlled
incinerator with respect to both the emissions control device and
hazardous waste metals and chlorine feedrate, the incinerator must
use a wet scrubber for hydrochloric acid and mercury control and
must use either a fabric filter, ionizing wet scrubber, or
electrostatic precipitator and achieve the floor particulate matter
level of 0.015 gr/dscf. Similarly, cement kilns must achieve the
particulate matter MACT floor (for this analysis only, the New
Source Performance Standard was converted to an estimated equivalent
stack gas concentration of 0.03 gr/dscf) and lightweight aggregate
kilns must meet the particulate matter MACT floor of 0.025 gr/dscf.
There is no MACT floor hydrochloric acid emissions control device
for cement kilns and lightweight aggregate kilns.
\64\ This aggregate hazardous waste MTEC ranking is done
separately for each of the three combustor source categories.
\65\ USEPA, ``Final Technical Support Document for HWC MACT
Standards, Volume III: Selection of MACT Standards and
Technologies,'' July 1999.
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The aggregate MTEC ranking process results in aggregate feedrate
data from nine incinerators, 10 cement kilns, and 10 lightweight
aggregate kilns from which to select an appropriate level of feedrate
control representative of MACT floor control.66 We
considered selecting the source with either the highest or lowest
aggregate MTEC in each source category to represent MACT floor control,
but did not believe this was appropriate based on concerns about
representativeness and achievability. We conclude that it is
reasonable, however, to consider the best 50% of the sources for which
we have data in each source category as the best performing sources.
This is because, for incinerators and cement kilns, we have only a few
sources with complete aggregate MTEC data relative to the size of the
source category. The best 50% of the sources for these categories
equates to five sources, given that we have aggregate MTEC data for
nine incinerators and 10 cement kilns. For lightweight aggregate kilns,
this equates also to five sources given that we have aggregate MTEC
data for 10 lightweight aggregate kiln sources.
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\66\ Only nine incinerators were ultimately used because (1) We
have complete metal emissions data on relatively few sources, and
(2) many sources do not use particulate matter floor control, a
major means of controlling semivolatile metals and low volatile
metals.
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Additionally, we conclude it is appropriate to identify a feedrate
MTEC representative of floor control based on the median of the best
performing five sources. In selecting a representative sample and
identifying the appropriate MTEC floor control level, we draw guidance
from section 112(d)(3)(B), in which Congress requires the Agency to use
the average of the best performing five sources when faced with small
source categories (i.e., less than 30 sources), and therefore limited
data, to establish a MACT floor. In addition, this methodology is
reasonable and appropriate because it allows consideration of a number
of best performing sources (i.e., five), which is within the range of
reasonable values we could have selected.
We considered an approach that selected both the control technique
and level of control as the average of the best performing 12% of
incinerator and
[[Page 52856]]
cement kiln sources for which we have aggregate MTEC data. This
approach resulted in using only the best single source as
representative of MACT floor control for all existing sources because
there are only nine incinerators and 10 cement kilns for which we have
adequate aggregate data. However, the level of feedrate control
achieved by the single best performing existing source is likely not
representative of the range of higher feedrate levels achieved by the
best performing existing sources and, indeed, would inappropriately
establish as a floor what amounts to a new source standard.
The final step of the aggregate feedrate approach is to determine
an emission level that is routinely achieved by sources using MACT
floor control(s). Similar to the April 1996 NPRM and May 1997 NODA, we
evaluated all available data for each test condition to determine if a
hazardous air pollutant is fed at levels at or below the MACT floor
control MTEC. If so, the test condition is added to the expanded MACT
pool for that hazardous air pollutant.67 We then define the
floor emission level for the hazardous air pollutant/hazardous air
pollutant group as the level achieved by the source with the highest
emissions average in the MACT expanded pool.
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\67\ The expanded MACT pool for each hazardous air pollutant is
comprised of test conditions from sources equipped with the
prescribed MACT floor emission control device, if any, and feeding
hazardous waste at an MTEC not exceeding the MACT floor MTEC for
that hazardous air pollutant.
---------------------------------------------------------------------------
The aggregate feedrate approach is a logical and reasonable
outgrowth of the aggregate hazardous air pollutant approach to
establish floor emission levels that we discussed in the April 1996
NPRM. The initial proposal determined MACT floors separately for each
hazardous air pollutant controlled by a different control technology,
but we also proposed an alternative whereby floors would be set on the
basis of a source's performance for all hazardous air pollutants.
Many commenters prefer the total aggregate hazardous air pollutant
approach over the individual hazardous air pollutant approach because
it better ensures that floor levels would be simultaneously achievable.
However, we reject the total aggregate approach because it tends to
result in floors that are likely to be artificially high, reflective of
limited emissions data for all hazardous air pollutants at each
facility. These floor levels, therefore, would not reflect performances
of the best performing sources for particular hazardous air pollutants.
We are assured of simultaneous achievability in our final methodology
by: (1) Establishing the MACT floor feedrate control levels on an
aggregate basis for metals and chlorine, as discussed above, rather
than for each individual hazardous air pollutant; (2) using the
particulate matter MACT pool to establish floor levels for particulate
matter, semivolatile metals, and low volatile metals; and (3) ensuring
that floor controls are not technically incompatible. In fact, our
resulting floor emission levels are already achieved in practice by 9
to 40 percent of sources in each of the three source categories,
clearly indicating simultaneously achievable standards.68
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\68\ Our analysis shows that approximately nine percent of
incinerators, 27 percent of cement kilns, and 40 percent of
lightweight aggregate kilns currently operating can meet all of the
floor levels simultaneously. See USEPA, ``Final Technical Support
Document For HWC MACT Standards, Volume V: Emissions Estimates and
Engineering Costs,'' July 1999.
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C. What Other Floor Methodologies Were Considered?
This is a brief overview of the major features of the MACT floor
methodologies that we proposed in the April 1996 NPRM or discussed in
the May 1997 NODA, accompanied by our rationale for not pursuing those
methodologies in this final rule.
1. April 19, 1996 Proposal
We proposed the same general approach to identify floor control and
floor emission levels as used in today's final rule. The proposal
contained an approach to identify the controls used by the best
performing sources (i.e., the MACT pool) and then identify an emission
level that those controls are achieving. To identify the floor emission
level, we considered emissions from all sources using properly designed
and operated controls (i.e., the expanded MACT pool) and established a
preliminary floor level as the highest test condition average for those
sources.
There are three major differences between the proposed approach and
today's final approach, however:
a. Emissions Variability. At proposal, we added a statistically-
derived emissions variability factor to the highest test condition
average in the expanded MACT pool. Today we conclude that emissions
variability is considered inherently in the floor methodology. (See
discussion in section D below for our rationale for not using a
statistically-derived variability factor.)
b. MACT Pool for Particulate Matter, Semivolatile Metals, and Low
Volatile Metals. At proposal, we identified separate and different MACT
pools (and associated MACT controls) for particulate matter,
semivolatile metals, and low volatile metals, even though all three are
controlled by a particulate matter control device. Commenters said this
is inappropriate and we concur. Specifying the MACT floor particulate
matter emission control device individually for these pollutants is
likely to result in three different definitions of floor control. Thus,
the same particulate matter control device would need to meet three
different design specifications. As a practical matter, the more
stringent specification would prevail. But, this highlights the
impracticability of evaluating floor emission control for these
standards individually rather than in the aggregate.
As discussed in the May 1997 NODA, today's approach uses the same
initial MACT pool to establish the floor levels for particulate matter,
semivolatile metals, and low volatile metals. The initial MACT pool is
comprised of those sources meeting the emission control component of
MACT control. To establish the semivolatile metal and low volatile
metal floor levels, the particulate matter MACT pool is then analyzed
to consider MACT hazardous waste feedrate control first for
semivolatile metals and then for low volatile metals, using the
aggregate feedrate approach discussed above.
c. Definition of MACT Control. At proposal, we defined MACT
emissions control by specifying the design of the emissions control
device. Commenters suggested that this was problematic because: (1) Our
data base had limited data on design of the control device; (2) some of
our available data were incorrect; and (3) the parameters the Agency
was using to characterize MACT control did not adequately correlate
with control efficiency. Given these concerns, our May 1997 NODA
contained an emissions breakpoint approach to identify those sources
that appeared to have anomalously higher emissions than other sources
in the potential MACT pool. Our rationale was that given the
anomalously high emissions, those sources were not, in fact, using MACT
control.
Commenters express serious concerns about the validity of the
nonstatistical approach used to identify the breakpoint. After
considering various statistical approaches to identify an emissions
breakpoint, we conclude that the emissions breakpoint approach is
problematic.69 For these reasons, we are
[[Page 52857]]
not defining MACT emissions control by design parameters or using an
emissions breakpoint approach to identify MACT emissions or feedrate
control. Rather, the MACT floor emission control equipment, where
applicable, is defined generically (e.g., electrostatic precipitator,
fabric filter), and the aggregate feedrate approach is used to define
MACT floor feedrates. We believe the aggregate feedrate approach
addresses the concerns that commenters raise on the proposed approach
because it more clearly defines MACT control and relies less on
engineering judgment.
---------------------------------------------------------------------------
\69\ To improve the rigor of our breakpoint approach, we
investigated a modified Rosner ``outlier'' test that: (1) Uses a
single tailed test to consider only high ``outliers'' (i.e., test
conditions that anomalously high emissions, not necessarily true
outliers in the statistical sense); (2) presumes that any potential
``outliers'' are at the 80th percentile value or higher; and (3) has
a confidence level of 90 percent. We abandoned this statistical
approach because: (1) Although modifications to the standard Rosner
test were supportable, the modified test has not been peer-reviewed;
(2) although the target confidence level was 90 percent, the true
significance level of the test, as revised, is inappropriately low--
approximately 80 percent; and (3) the ``outlier'' test does not
identify MACT-like test conditions because it only identifies
anomalously high test conditions rather than the best performing
test conditions.
---------------------------------------------------------------------------
2. May 1997 NODA
We have incorporated into the final rule several of the procedures
discussed in the May 1997 NODA. The NODA explained why it is
inappropriate to add a statistically-derived emissions variability
factor to the highest test condition average of the expanded MACT pool.
Despite comments to the contrary, we conclude that emissions
variability is inherently considered in the floor methodology. See
discussion in section D below.
In addition, the NODA discussed using the same initial MACT pool to
establish the floor levels for particulate matter, semivolatile metals,
and low volatile metals. We use this same approach in this final rule.
Commenters generally concurred with that approach.
As discussed above, we considered using an emissions breakpoint
technique, but conclude that this approach is problematic and did not
use the approach for this rule.
D. How Is Emissions Variability Accounted for in Development of
Standards?
The methodology we use to establish the final MACT emission
standards intrinsically accounts for emissions variability without
adding statistically-derived emissions variability factors. Many
commenters strongly suggest that statistically-derived emissions
variability factors must be added to the emission levels we identify
from the data base as floor emission levels to ensure that the
standards are routinely achievable.70 Other commenters
suggest that our floor methodology inherently accounts for emissions
variability. We discuss below the types of emissions variability and
why we conclude that emissions variability is inherently accounted for
by our methodology.
---------------------------------------------------------------------------
\70\ One commenter recommends specific statistical approaches to
calculate variability factors and provides examples of how the
statistical methods should be applied to our emissions data base.
See comment number CS4A-00041.
---------------------------------------------------------------------------
We account for three types of emissions variability in establishing
MACT standards: (1) Within test condition variability among test runs
(a test condition is comprised of at least three runs that are
averaged); (2) imprecision in the stack test method; and (3) source-to-
source emissions variability attributable to source-specific factors
affecting the performance of the same MACT control device. (See, e.g.
FMC Corp. v. Train, 539 F.2d 973, 985-86 (4th Cir. 1976), holding that
variability in performance must be considered when ascertaining whether
a technology-based standard is achievable.) The following sections
discuss the way in which we account for these types of variability in
the final rule.
1. How Is Within-Test Condition Emissions Variability Addressed?
Inherent process variability will cause emissions to vary from run-
to-run within a test condition, even if the stack method is 100 percent
precise and even though the source is attempting to maintain constant
operating conditions. This is caused by many factors including: Minor
changes in the feedrate of feedstreams; combustion perturbations (e.g.,
uncontrollable, minor fluctuations in combustion temperature or fan
velocity); changes in the collection efficiency of the emission control
device caused by fluctuations in key parameters (e.g., power input to
an electrostatic precipitator); and changes in emissions of materials
(e.g., sulfur dioxide) that may cause test method interferences.
At proposal, we used a statistical approach to account for
emissions variability. See 61 FR at 17366. The statistical approach
identified an emissions variability factor, which was added to the log-
mean of the emission level being achieved based on the available
``short-term'' compliance test data. We called this emission level the
``design level.'' The variability factor was calculated to ensure that
the design level could be achieved 99 percent of the time, assuming
average within-test condition emissions variability for the source
using MACT control.
In the May 1997 NODA, we discussed alternative emission standards
developed without using a statistically-derived variability factor.
Adding such a variability factor was determined inappropriate because
it sometimes resulted in nonsensical results. For example, the
particulate matter MACT floor level for incinerators under one floor
methodology would have been higher than the current RCRA standard
allows, simply due to the impact of an added variability factor. In
other cases, the floor levels would have been much higher than our
experience would indicate are routinely being achieved using MACT
control. We reasoned that these inappropriate and illogical results may
flow from either the data base used to derive the variability factor
(e.g., we did not have adequate information to screen out potentially
outlier runs on a technical basis) or selecting an inappropriate floor-
setting test condition as the design level (e.g., we did not have
adequate information on design, operation, and maintenance of emissions
control equipment used by sources in the emissions data base to
definitively specify MACT control).
Consequently, we reasoned that adequately accounting for within
test condition emissions variability is achieved where relatively large
data sets are available to evaluate for identifying the floor level.
Large sets of emissions data from MACT sources, which have emissions
below the floor level, are likely to represent the range of emissions
variability. For small data sets (e.g., dioxin/furan emissions for
waste heat recovery boiler equipped incinerators; dioxin/furan
emissions data for lightweight aggregate kilns), we acknowledged that
the same logic would not apply. For these small data sets, the floor
level was set at the highest run for the MACT source with the highest
test condition average emissions. Many commenters suggest that our
logic was flawed. Commenters say that, if we desire the floor level to
be achievable 99 percent of the time (i.e., the basis for the
statistically-derived variability factor at proposal), the emissions
data base is far too small to identify the floor level as the highest
test condition average for sources using MACT control.
We conclude, however, that the final floor levels identified, using
the procedures discussed above (i.e., without adding a statistically-
derived emissions variability factor), are levels that can be
consistently achieved by well designed, operated, and maintained MACT
sources. We
[[Page 52858]]
conclude this because our emissions data base is comprised of
compliance test data generated when sources have an incentive to
operate under worst case conditions (e.g., spiking metals and chlorine
in the waste feed; detuning the emissions control equipment). Sources
choose to operate under worst case conditions during compliance testing
because the current RCRA regulations require that limits on key
operating parameters not exceed the values occurring during the trial
burn. Therefore, these sources conduct tests in a manner that will
establish a wide envelope for their operating parameter limits in order
to accommodate the expected variability (e.g., variability in types of
wastes, combustion system parameters, and emission control parameters).
See 56 FR at 7146 where EPA likewise noted that certain RCRA operating
permit test conditions are to be ``representative of worst-case
operating conditions'' to achieve needed operating flexibility. One
company that operates several hazardous waste incinerators at three
locations comments that, because of the current RCRA compliance regime,
which is virtually identical to the compliance procedures of today's
MACT rule, ``the result is that units must be tested at rates which are
at least three standard deviations harsher than normal operations and
normal variability in order to simulate most of the statistical
likelihood of allowable emission rates.'' 71 The commenter
also states that because of the consequences of exceeding an operating
parameter limit under MACT, ``* * * clearly a source will test under
the worst possible operating conditions in order to minimize future
(exceedances of the limits).'' Finally, the commenter says that
``Because of variability and the stiff consequences of exceeding these
limits, operators do not in fact operate their units anywhere near the
limits for sustained periods of time, but instead tend to operate
several standard deviations below them, or at about 33 to 50% of the
limits.'' 72
---------------------------------------------------------------------------
\71\ See Comment No. CS4A-00029.A, dated August 16, 1996.
\72\ To estimate the compliance cost of today's rule, we assumed
that sources would design their systems to meet an emission level
that is 70% of the standard, herein after called the ``design
level.''
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We conclude from these comments, which are consistent with
engineering principles and with many discussions with experts from the
regulated community, that MACT sources with compliance test emissions
at or below the selected floor level are achieving those levels
routinely because these test conditions are worst-case and are defined
by the source itself to ensure 100 percent compliance with the relevant
standard.
We acknowledge, however, that mercury is a special case because our
mercury emission data may not be representative of worst-case
conditions. As discussed in Section I.B.3 above, sources did not
generally spike mercury emissions during RCRA compliance testing
because they normally feed mercury at levels resulting in emissions
well below current limits.73 Although our data base for
mercury is comprised essentially of normal emissions, emissions
variability is adequately accounted for in setting floor levels. First,
mercury emissions variability is minimal because the source can readily
control emissions by controlling the feedrate of mercury.74
For cement and lightweight aggregate kilns, mercury is controlled
solely by controlling feedrate. Given that there is no emission control
device that could have perturbations affecting emission rates,
emissions variability at a given level of mercury feedrate control is
relatively minor. Any variability is attributable to variability in
feedrate levels due to feedstream sampling and analysis imprecision,
and stack method imprecision (see discussion below).
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\73\ Three of 23 incenerators used to define MACT floor (i.e.,
sources for which mercury feedrate data are available) are known to
have spiked mercury. No cement kilns used to define MACT floor
(e.g., excluding sources that have stopped burning hazardous waste)
are known to have spiked mercury. Only one of ten lightweight
aggregate kilns used to define MACT floor is known to have spiked
mercury.
\74\ Although incenerators are generally equipped with wet
scrubbers that can have a mercury removal efficiency of 15 to 60
percent, feedrate control is nonetheless the primary means of
mercury emissions control because of the relatively low removal
efficiency provided by wet scrubbers.
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Second, our emissions data indicate that the mercury floor levels
are being achieved by a wide margin, which is a strong indication that
a variability factor is not needed. Only one of the 15 incinerators
using MACT floor control exceeds the design level for the floor
emission level.75 In addition, only seven of 45 incinerators
for which we have mercury emissions data exceed the design level, and
two of those eight are know to have spiked mercury in the hazardous
waste feed during compliance testing. Only six of the 45 incinerators
exceed the floor emission level.
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\75\ Commenters note that the mercury levels fed during RCRA
compliance testing may not represent the normal range of feedrates,
and thus the compliance test emission levels may not be
representative of emission levels achieved in practice. Given that
only one of 15 incinerators using floor control exceeds the design
level, it appears that the floor emission level is, in fact, being
achieved in practice. Some of these 15 sources were likely feeding
mercury at the high end of their normal range, even though others
may have been feeding mercury at normal or below normal levels. This
is also the situation of cement kilns where only two of 2 kilns
using floor control exceed the design level, and for lightweight
aggregate kilns where only one of nine kilns using floor exceeds the
design level.
---------------------------------------------------------------------------
The situation is similar for cement kilns and lightweight aggregate
kilns. Only two of 22 cement kilns using floor control exceed the
design level, only five of the 33 kilns in the source category exceed
the design level, and only one of the 33 kilns exceeds the floor
emission level. Only one of nine lightweight aggregate kilns using
floor control exceeds the design level, and only two of the 10 kilns in
the source category exceed the design level (and one of those kilns is
known to have spiked mercury in the hazardous waste feed during
compliance testing). Only one of the 10 kilns exceeds the floor
emission level, and that kiln spiked mercury.
We conclude from this analysis that the mercury floor emission
levels in this rule are readily achieved in practice even though our
mercury emissions data were not spiked (i.e., they may not represent
worst-case emissions), and therefore a separate variability factor is
not needed.
2. How Is Waste Imprecision in the Stack Test Method Addressed?
Method precision is a measure of how closely emissions data are
grouped together when measuring the same level of stack emissions
(e.g., using a paired or quad test train). Method imprecision is
largely a function of the ability of the sampling crew and analytical
laboratory to routinely follow best practices. Precision can be
affected by: (1) Measurement of ancillary parameters including gas flow
rate, pressure, and temperature; (2) recovery of materials from the
sampling train; and (3) cleaning, concentrating, and quantitating the
analyte.
Several commenters state that we must add a factor to the selected
floor level to account for method imprecision in addition to a factor
to account for within-test condition emissions variability. We
investigated the imprecision for the stack methods used to document
compliance with today's rule and determined that method imprecision may
be significant for some hazardous air pollutant/method
combinations.76 Our results indicate, however, that method
precision is much better than commenters claim, and that as additional
data sets become available,
[[Page 52859]]
the statistically-derived precision bars for certain pollutants are
reasonably expected to be reduced significantly. This is mainly because
data should become available over a wider range of emission levels thus
reducing the uncertainty that currently results in large precision bar
projections for some hazardous air pollutants at emission levels that
are not close to the currently available paired and quad-train
emissions data.
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\76\ USEPA, ``Final Technical Support Document for HWC MACT
Standards, Volume III: Selection of MACT Standards and
Technologies,'' July 1999.
---------------------------------------------------------------------------
We conclude that method imprecision, in selecting the floor levels
for hazardous waste combustors, is adequately addressed for the same
reasons that we accounted for within-test condition emissions
variability. Method precision is simply a factor that contributes to
within-test condition variability. As discussed above, sources consider
emissions variability when defining their compliance test operating
conditions to balance emissions standards compliance demonstrations
with the need to obtain a wide operating envelope of operating
parameter limits.
3. How Is Source-to-Source Emissions Variability Addressed?
If the same MACT control device (i.e., same design, operating, and
maintenance features) were used at several sources within a source
category, emissions of hazardous air pollutants from the sources could
vary. This is because factors that affect the performance of the
control device could vary from source to source. Even though a device
has the same nominal design, operating, and maintenance features, those
features could never be duplicated exactly. Thus, emissions could vary
from source to source.
We agree that this type of emissions variability must be accounted
for in the standards to ensure the standards are achieved in practice.
Source-to-source emissions variability is addressed by identifying the
floor emission level as the highest test condition average for sources
in the expanded MACT pool, as discussed above.77
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\77\ Because of the need to account for this type of
variability, we disagree with those commenters recommending that:
(1) The floor emission level be identified as the average emission
level achieved by the 12 percent of source with the lowest
emissions; and (2) it is inappropriate to base the floor emission
level on sources using floor control but that are not within the 12
percent of sources with the lowest emissions (i.e., the expanded
MACT pool should not be used to identify floor emission levels). The
floor emission level must be achieved in practice by sources using
the appropriately designed and operated floor control. Thus,
emission levels being achieved by all sources using the
appropriately designed and operated floor control (i.e., including
sources using floor control but having emission levels greater than
the average of the emissions achieved by the 12 percent of sources
with the lowest emissions) must be considered when identifying the
floor emission level.
---------------------------------------------------------------------------
The test condition average emissions for sources in the expanded
MACT pool for most standards often vary over several orders of
magnitude. That variability is attributable partially to the type of
source-to-source emissions variability addressed here as well as the
inclusion of sources with varying levels of MACT control in the pool.
Sources are included in the expanded MACT pool if they have controls
equivalent to or better than MACT floor controls. We are unable to
identify true source-to-source emissions variability for sources that
actually have the same MACT controls because we are unable to specify
in sufficient detail the design, operating, and maintenance
characteristics of MACT control. Such information is not readily
available. Therefore, we define MACT control only in general terms.
This problem (and others) are addressed in today's rule by selecting
the MACT floor level based on the highest test condition average in the
expanded MACT pool, which accounts for source-to-source variability.
We also conclude that the characteristics of the emissions data
base coupled with the methodology used to identify the floor emission
level adequately accounts for emissions variability so that the floor
level is routinely achieved in practice by sources using floor control.
As further evidence, we note that a large fraction--50 to 100 percent--
of sources in the data base currently meet the floor levels regardless
of whether they currently use floor control.78
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\78\ USEPA, ``Final Technical Support Document for HWC MACT
Standards, Volume III: Selection of MACT Standards and
Technologies,'' July 1999.
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VI. What Are the Standards for Existing and New Incinerators?
A. To Which Incinerators Do Today's Standards Apply?
The standards promulgated today apply to each existing,
reconstructed, and newly constructed incinerator (as defined in 40 CFR
260.10) burning hazardous waste. These standards apply to all major
source and area source incinerator units and to all units whether they
are transportable or fixed sources. These standards also apply to
incinerators now exempt from RCRA stack emission standards under
Secs. 264.340(b) and (c).\79\ Additionally, these standards apply to
thermal desorbers that meet the definition of a RCRA incinerator, and
therefore, are not regulated under subpart X of part 264.
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\79\ Sections 264.340(b) and (c) exempt from stack emission
standards incinerators (a) burning solely ignitable, corrosive or
reactive wastes under certain conditions, and (b) if the waste
contains no or insignificant levels of hazardous constituents.
---------------------------------------------------------------------------
B. What Subcategorization Options Did We Evaluate?
We considered whether it would be appropriate to subcategorize
incinerators based on several factors discussed below and conclude that
subcategorization is not necessary. However, for waste heat recovery
boiler-equipped incinerators, we establish a separate emission standard
solely for dioxin/furan. We explained our rationale for separate
dioxin/furan standards for waste heat recovery boilers in the May 1997
NODA (62 FR 24220). We said that waste heat recovery boilers emit
significantly higher dioxin/furan emissions than other incinerators,
probably because the heat recovery boiler precludes rapid temperature
quench of the combustion gases to below 400 deg.F, therefore warranting
separate standards for dioxin/furan only (i.e., the waste heat boiler
does not affect achievability of the other emission standards).
We considered several options for subcategorizing the hazardous
waste incinerator source category based on: (1) Size of the unit (e.g.,
small and large incinerators); (2) method of use of the hazardous waste
incinerator (e.g., commercial hazardous waste incinerator, captive (on-
site) unit); (3) facility design (e.g., rotary kiln, liquid injection,
fluidized bed, waste heat boiler), and (4) type of waste fed (e.g.,
hazardous waste mixed with radioactive waste, munitions, liquid, solid
or aqueous wastes). Subcategorization would be appropriate if one or
more of these factors affected achievability of emission standards that
were established without subcategorization. In the May 1997 NODA (62 FR
24219), we stated that subdividing the hazardous waste incinerator
source category by size or method of use (such as commercial or on-
site) would be inappropriate because it would not result in standards
that are more achievable. Many of the standards would be the same for
the subcategories while the remainder would be more stringent. That
conclusion is not altered by any of the changes in today's final rule.
Therefore, subcategorization would add complexity without any tangible
achievability benefits.
In the same notice, we also requested comment on subcategorization
and/or a deferral of standards for mixed waste incinerators based on a
comment from the Department of Energy that this type of incinerator has
several unique features that warrant subcategorization.
[[Page 52860]]
There are three Department of Energy mixed waste incinerators. Each
mixed waste incinerator has a different type of operation and different
air pollution control devices, and two of the sources have high dioxin/
furan and mercury emissions (several times the dioxin/furan standards
adopted in today's rule). We received several comments on the mixed
waste incinerator issue. These commenters contend that, because of the
radioactive component of the wastes, mixed waste incinerators pose
greater than average risk, and regulating these facilities should not
be deferred. These commenters also note that the MACT controls are not
incompatible with mixed waste incinerators and thus these incinerators
can readily achieve the emission standards. We agree that MACT controls
are compatible with mixed waste incinerators, with one exception
discussed below, and do not establish a mixed waste incinerator
subcategory.
The standards promulgated today are generally achievable by all
types and sizes of incinerators when using MACT controls. We recognize,
however, that each of the possible subcategories considered has some
unique features. At the same time, upon consideration of each
individual issue, we conclude that unique features of a particular
hazardous waste incinerator can be better dealt with on an individual
basis (through the permit process or through petitions) instead of
through extensive subcategorization. As an example, we agree with the
Department of Energy's contentions that feedstream testing for metals
is problematic for mixed waste incinerators due to radioactivity of the
waste and because risk from metal emissions is minimal in mixed waste
incinerators that use HEPA filters to prevent radioactive emissions.
Section 63.1209(g)(1) of today's rule provides a mechanism for
petitioning the Administrator for use of an alternative monitoring
method.80 This petition process appears to be an appropriate
vehicle for addressing the concerns expressed by the Department of
Energy about feedstream testing for metals and use of HEPA filters at
its mixed waste incinerators.
---------------------------------------------------------------------------
\80\ The petition for an alternative monitoring method should be
included in the comprehensive performances test plan submitted for
review and approval.
---------------------------------------------------------------------------
In summary, our decision not to subcategorize hazardous waste
incinerators is based on four reasons:
(1) Size differences among hazardous waste incinerators do not
necessarily reflect process, equipment or emissions differences among
the incinerators. Many small size hazardous waste incinerators have
emissions lower than those promulgated today even though they are not
regulated to those low levels.
(2) Types and concentrations of uncontrolled hazardous air
pollutants are similar for all suggested subcategories of hazardous
waste incinerators.
(3) The same type of control devices, such as electrostatic
precipitators, fabric filters, and scrubbers, are used by all hazardous
waste incinerators to control emissions of particular hazardous air
pollutants.
(4) The standards are achievable by all types and sizes of well
designed and operated incinerators using MACT controls.
C. What Are the Standards for New and Existing Incinerators?
1. What Are the Standards for Incinerators?
We discuss in this section the basis for the emissions standards
for incinerators. The emissions standards are summarized below:
Standards for Existing and New Incinerators
----------------------------------------------------------------------------------------------------------------
Emissions standard \1\
Hazardous air pollutant or ------------------------------------------------------------------------------
hazardous air pollutant surrogate Existing sources New sources
----------------------------------------------------------------------------------------------------------------
Dioxin /Furan.................... 0.20 ng TEQ \2\/ 0.20 ng TEQ/dscm.
dscm; or 0.40 ng
TEQ/dscm and
temperature at
inlet to the
initial
particulate matter
control device 400 deg.F.
Mercury.......................... 130 g/dscm 45 g/dscm.
Particulate Matter............... 34mg/dscm (0.015gr/ 34mg/dscm (0.015gr/dscf).
dscf).
Semivolatile Metals.............. 240 g/dscm 24 g/dscm.
Low Volatile Metals.............. 97 g/dscm. 97 g/dscm.
Hydrochloric Acid/Chlorine Gas... 77 ppmv............ 21 ppmv.
Hydrocarbons 3, 4................ 10 ppmv (or 100 10 ppmv (or 100 ppmv carbon monoxide).
ppmv carbon
monoxide).
Destruction and Removal 99.99% for each Same as for existing incinerators.
Efficiency. specific principal
organic hazardous
constituent,
except 99.9999%
for specified
dioxin-listed
wastes.
----------------------------------------------------------------------------------------------------------------
\1\ All emission levels are corrected to 7 percent oxygen.
\2\ Toxicity equivalent quotient, the international method of relating the toxicity of various dioxin/furan
congeners to the toxicity of 2,3,7,8-TCDD.
\3\ Hourly rolling average. Hydrocarbons reported as propane.
\4\ Incinerators that elect to continuously comply with the carbon monoxide standard must demonstrate compliance
with the hydrocarbon standard of 10ppmv during the comprehensive performance test.
2. What Are the Standards for Dioxins and Furans?
We establish a dioxin/furan standard for existing incinerators of
either 0.20 ng TEQ/dscm, or a combination of dioxin/furan emissions up
to 0.40 ng TEQ/dscm and temperature at the inlet to the initial dry
particulate matter control device not to exceed 400 deg.F.81
Expressing the standard as a temperature limit as well as a dioxin/
furan concentration limit provides better control of dioxin/furan,
because sources operating at temperatures below 400 deg.F generally
have lower emissions and is consistent with the current practice of
many sources. Further, without the lower alternative TEQ limit of 0.20
ng/dscm, sources that may be operating dry particulate matter control
devices at temperatures higher than 400 deg.F while achieving dioxin/
furan emissions below 0.20 ng TEQ/dscm would nonetheless be required to
incur costs to lower gas temperatures. This would not be appropriate
because lowering gas temperatures in this case would likely
[[Page 52861]]
achieve limited reductions in dioxin/furan emissions (i.e., because
emissions are already below 0.20 ng TEQ).
---------------------------------------------------------------------------
\81\ Incinerators that use wet scrubbers as the initial
particulate matter control device are presumed to meet the 400 deg.F
temperature requirement. Consequently, as a practical matter, the
standard for such incinerators is simply 0.4 ng TEQ/dscm.
---------------------------------------------------------------------------
For new incinerators, the dioxin/furan standard is 0.20 ng TEQ/
dscm. We discuss below the rationale for these standards.
a. What is the MACT Floor for Existing Sources? We establish the
same MACT floor control, as was evaluated in the May 1997 NODA, based
on the revised data base and the refinements to the analytical
approaches. This floor control is based on quenching of combustion
gases to 400 deg.F or below at the dry particulate matter control
device.82 We selected a temperature of 400 deg.F because
that temperature is below the temperature range for optimum surface-
catalyzed dioxin/furan formation reactions--450 deg.F to 650 deg.F--and
most sources operate their particulate matter control device below that
temperature. In addition, temperature is an important control parameter
because dioxin/furan emissions increase exponentially as combustion gas
temperatures at the dry particulate matter control device increase
above 400 deg.F.
---------------------------------------------------------------------------
\82\ The temperature limit applies at the inlet to a dry
particulate matter control device that suspends particulate matter
in the combustion gas stream (e.g., electrostatic precipitator,
fabric filter) such that surface-catalyzed formation of dioxin/furan
is enhanced. The temperature limit does not apply to a cyclone
control device, for example.
---------------------------------------------------------------------------
We identify a MACT floor level of 0.40 ng TEQ/dscm for incinerators
other than those equipped with waste heat recovery boilers. As
discussed in the May 1997 NODA, the floor level of 0.40 ng TEQ/dscm is
based on the highest nonoutlier test condition for sources equipped
with dry particulate matter control devices operated at temperatures of
400 deg.F or below or wet particulate matter control devices. We
screened out four test conditions from three facilities because they
have anomalously high dioxin/furan emissions and are not representative
of MACT control practices.83 Three of these test conditions
are from sources that had other test conditions with emission averages
well below 0.40 ng TEQ/dscm, indicating that the same facilities can
achieve lower emission levels in different operating modes.
---------------------------------------------------------------------------
\83\ USEPA, ``Technical Support Document for HWC MACT Standards,
Volume III: Selection of MACT Standards and Technologies,'' July
1999, Section 3.1.1.
---------------------------------------------------------------------------
We identify a MACT floor level for waste heat boiler-equipped
hazardous waste incinerators of 12 ng TEQ/dscm based on the highest
emitting individual run for sources equipped with dry particulate
matter control devices operated at temperatures of 400 deg.F or below
or wet particulate matter control devices. We use the highest run to
set the floor level rather than the average of the runs for the test
condition to address emissions variability concerns given that we have
a very small data set for waste heat boilers. All waste heat boiler-
equipped hazardous waste incinerators meet this floor level, except for
a new test conducted after the publication of the May 1997 NODA at high
temperature conditions that resulted in dioxin/furan emission levels of
47 ng TEQ/dscm. This source is not using MACT control, however, because
the temperature at the particulate matter control device exceeded
400 deg.F. Thus, we do not consider emissions from this source in
identifying the floor level.
We received numerous and diverse comments on the April 1996
proposal and the May 1997 NODA. While some commenters consider the
dioxin/furan standards too high, a large number comment that the
standards are too stringent. Many comment that the methodology used for
calculating the dioxin/furan MACT floor level is inappropriate and that
the cost-effectiveness of the standards is not reasonable. In
particular, some commenters suggest separating ``fast quench'' and
``slow quench'' units. We have fully addressed this latter concern
because we now establish separate dioxin/furan standards for waste heat
boilers given that they are a fundamentally different type of process
and that they have higher dioxin/furan emissions because of the slow
quench across the boiler. We address the other comments elsewhere in
the preamble and in the comment response document.
Approximately 65% of all test conditions at all incinerator sources
are achieving the 0.40 ng TEQ/dscm level, and over 50% of all test
conditions achieve the 0.20 ng TEQ/dscm level. We estimate that
approximately 60 percent of incinerators currently meet the TEQ limit
as well as the temperature limit. Under the statute, compliance costs
are not to be considered in MACT floor determinations. For purposes of
compliance with Executive Order 12866 and the Regulatory Flexibility
Act, we calculated the annualized cost for hazardous waste incinerators
to achieve the dioxin/furan MACT floor levels. Assuming that no
hazardous waste incinerator exits the market due to MACT standards, the
annual cost is estimated to be $3 million, and the standards will
reduce dioxin/furan emissions nationally by 3.4 g TEQ per year from the
baseline emissions level of 24.8 g TEQ per year.
b. What Are Our Beyond-the-Floor Considerations for Existing
Sources? We investigated the use of activated carbon injection, along
with limiting temperatures at the inlet to the initial dry particulate
matter control device to 400 deg.F,84 to achieve two
alternative beyond-the-floor emission levels: (1) 0.40 ng TEQ/dscm for
waste heat boiler-equipped incinerators (i.e., slow quench) to reduce
their emissions to the floor level for other incinerators; and (2) 0.20
ng TEQ/dscm for all incinerators. Activated carbon injection technology
is feasible and proven to reduce dioxin/furan emissions by 99 percent
or greater.85 It is currently used by one waste heat boiler-
equipped hazardous waste incinerator (Waste Technologies Industries in
East Liverpool, Ohio) and many municipal waste combustors.86
The removal efficiency of an activated carbon injection system is
affected by several factors including carbon injection rate and
adsorption quality of the carbon. Thus, activated carbon injection
systems can be used by waste heat boiler-equipped incinerators to
achieve alternative beyond-the-floor emissions of either 0.40 ng TEQ/
dscm or 0.20 ng TEQ/dscm.
---------------------------------------------------------------------------
\84\ Limiting the temperature at the dry particulate matter
control device reduces surface-catalyzed formation of dioxin/furan
and enhances the adsorption of dioxin/furan on the activated carbon.
\85\ USEPA, ``Technical Support Document for HWC MACT Standards,
Volume III: Selection of MACT Standards and Technologies,'' July
1999.
\86\ We have established in a separate rulemaking that activated
carbon injection is MACT floor control for municipal waste
combustors.
---------------------------------------------------------------------------
We conclude that a beyond-the-floor emission level of 0.40 ng TEQ/
dscm for waste heat boiler-equipped incinerators is cost-effective but
a 0.20 ng TEQ/dscm emission level for all incinerators is not cost-
effective. We estimate that 23 waste heat boiler-equipped incinerators
will need to install activated carbon injection systems at an
annualized cost of approximately $6.6 million. This will result in a
sizable reduction of 17.9 g TEQ dioxin/furan emissions per year and
will provide an 84 percent reduction in emissions from the floor
emission level (21.4 g TEQ per year) for all hazardous waste
incinerators. This represents a cost-effectiveness of $370,000 per gram
TEQ removed.
When we evaluated the alternative beyond-the-floor emission level
of 0.20 ng TEQ/dscm for all incinerators, we determined that 80
hazardous waste incinerators would incur costs to reduce dioxin/furan
emissions by 19.5 g TEQ from the floor level (21.4 g TEQ) at an
annualized cost of $16.1 million. The cost-effectiveness would be
$827,000 per gram of TEQ removed. In addition,
[[Page 52862]]
we determined that the vast majority of these emissions reductions
would be provided by waste heat boiler-equipped incinerators, and would
be provided by the beyond-the-floor emission level of 0.40 ng TEQ/dscm
discussed above. The incremental annualized cost of the 0.20 ng TEQ/
dscm option for incinerators other than waste heat boiler-equipped
incinerators would be $9.5 million, and would result in an incremental
reduction of only 1.6 g TEQ per year. This represents a high cost for a
very small additional emission reduction from the floor, or a cost-
effectiveness of $6.0 million per additional gram of TEQ dioxin/furan
removed. Accordingly, we conclude that the 0.20 ng TEQ/dscm beyond-the-
floor option is not cost-effective.
We note that dioxin/furan are some of the most toxic compounds
known due to their bioaccumulative potential and wide range of adverse
health effects, including carcinogenesis, at exceedingly low doses. We
consider beyond-the-floor reduction of dioxin/furan emissions a prime
environmental and human health consideration. As discussed above, our
data base indicates that a small subset of incinerators--those equipped
with waste heat recovery boilers--can emit high levels of dioxin/furan,
up to 12 ng TEQ/dscm, even when operating the dry particulate matter
control device at 400 deg.F. We are concerned that such high
dioxin/furan emission levels are not protective of human health and the
environment, as mandated by RCRA. If dioxin/furan emissions from waste
heat boiler-equipped incinerators are not reduced by a beyond-the-floor
emission standard, omnibus RCRA permit conditions would likely be
needed in many cases. This would defeat our objective of having only
one permitting framework for stack air emissions at hazardous waste
incinerators (except in unusual cases). Thus, the beyond-the-floor
standard promulgated today for waste heat boiler-equipped incinerators
is not only cost-effective, but also an efficient approach to meed the
Agency's RCRA mandate.
Some commenters suggest that the standard for waste heat boiler-
equipped hazardous waste incinerators, which is based on activated
carbon injection, be set at levels achieved by activated carbon
injection at the Waste Technologies Industries facility--an average of
0.07 ng TEQ/dscm. We determined that this would not be appropriate
because of concerns that such a low emission level may not be routinely
achievable. An emission level of 0.07 ng TEQ/dscm represents a 99.4
percent reduction in emissions from the floor level of 12 ng TEQ/dscm.
Although activated carbon injection can achieve dioxin/furan emissions
reductions of 99 percent and higher, we are concerned that removal
efficiency may decrease at low dioxin/furan emission levels. We noted
our uncertainty about how much activated carbon injection control
efficiency may be reduced at low dioxin/furan concentrations in the May
1997 NODA (62 FR at 24220). Several commenters agree with our concern,
including Waste Technologies Industries.87 No commenters
provide data or information to the contrary. Because we have data from
only one hazardous waste incinerator documenting that an emission level
of 0.07 ng TEQ can be achieved, we are concerned that an emission level
that low may not be routinely achievable by all sources.
---------------------------------------------------------------------------
\87\ Waste Technologies Industries suggested, however, that
after experience with activated carbon injection systems has been
attained by several hazardous waste incinerators, the Agency could
then determine whether an emission level of 0.07 ng TEQ/dscm is
routinely achievable. See comment number 064 in Docket F-97-CS4A-
FFFFF.
---------------------------------------------------------------------------
c. What Is the MACT Floor for New Sources? For new sources, the CAA
requires that the MACT floor be the level of control used by the best
controlled single source. As discussed above, one source, the Waste
Technologies Industries (WTI) incinerator in Liverpool, Ohio, uses
activated carbon injection. Therefore, we identify activated carbon
injection as MACT floor control for new sources. To establish the MACT
floor emission level that is being achieved in practice for sources
using activated carbon injection, data are available from only WTI. WTI
is achieving an emission level of 0.07 ng TEQ/dscm. As discussed above,
we are concerned that emission level may not be routinely achievable
because the removal efficiency of activated carbon injection may be
reduced at such low emission levels. An emission level of 0.20 ng TEQ/
dscm is routinely achievable, however. We note that activated carbon
injection is MACT floor control for dioxin/furan at new large municipal
waste combustors. We established a standard of 13 ng/dscm total mass
``equal to about 0.1 to 0.3 ng/dscm TEQ'' for these sources (60 FR
65396 (December 19, 1995)), equivalent to approximately 0.20 ng TEQ/
dscm. We conclude, therefore, that a floor level of 0.20 ng TEQ/dscm is
achievable for new sources using activated carbon injection and
accordingly set this as the standard.
d. What Are Our Beyond-the-Floor Considerations for New Sources? As
discussed in the May 1997 NODA, a beyond-the-floor standard below 0.20
ng TEQ/dscm would not be appropriate. Although installation of carbon
beds would enable new hazardous waste incinerators to achieve lower
dioxin/furan levels, we do not consider the technology to be cost-
effective. The reduction in dioxin/furan emissions would be very small,
while the costs of carbon beds would be prohibitively high. In
addition, due to the very small dioxin/furan reduction, the benefit in
terms of cancer risks reduced also will be very small. Therefore, we
conclude that a beyond-the-floor standard for dioxin/furan is not
appropriate.
3. What Are the Standards for Mercury?
We establish a mercury standard for existing and new incinerators
of 130 and 45 g/dscm respectively. We discuss below the
rationale for these standards.
a. What Is the MACT Floor for Existing Sources? We are establishing
the same MACT floor level as proposed, 130 g/dscm although, as
discussed below, the methodology underlying this standard has changed
from proposal. At proposal, the floor standard was based on the
performance of either: (1) Feedrate control of mercury at a maximum
theoretical emission concentration not exceeding 19 g/dscm; or
(2) wet scrubbing in combination with feedrate control of mercury at a
level equivalent to a maximum theoretical emission concentration not
exceeding 51 g/dscm. In the May 1997 NODA, we reevaluated the
revised data base and defined MACT control as based on performance of
wet scrubbing in combination with feedrate control of mercury at a
level equivalent to a maximum theoretical emission concentration of 50
g/dscm and discussed a floor level of 40 g/dscm.
Several commenters object to our revised methodology and are
concerned that we use low mercury feedrates to define floor control.
These commenters state that standards should not be based on sources
feeding very small amounts of a particular metal, but rather on their
ability to minimize the emissions by removing the hazardous air
pollutant. As discussed previously, we maintain that hazardous waste
feedrate is an appropriate MACT control technique. We agree with
commenters' concerns, however, that previous methodologies to define
floor feedrate control may have identified sources feeding anomalously
low levels of a metal (or chlorine). To address this concern, we have
revised the floor determination methodology for mercury, semivolatile
metals, low volatile metals and total chlorine. A
[[Page 52863]]
detailed description of this methodology--the aggregate feedrate
approach--is presented in Part Four, Section V of this preamble.
Adopting this aggregate feedrate approach, we identify a mercury
feedrate level that is approximately five times higher than the May
1997 NODA level and higher than approximately 70% of the test
conditions in our data base.
Wet scrubbers also provide control of mercury (particularly mercury
chlorides). Given that virtually all incinerators are equipped with wet
scrubbers (for control of particulate matter or acid gases), we
continue to define floor control as both hazardous waste feedrate
control of mercury and wet scrubbing. The MACT floor based on the use
of wet scrubbing and feedrate control of mercury is 130 g/
dscm.\88\
---------------------------------------------------------------------------
\88\ This is coincidentally the same floor level as proposed,
notwithstanding the use of a different methodology.
---------------------------------------------------------------------------
The floor level is being achieved by 80% of the test conditions in
our data base of 30 hazardous waste incinerators. As already discussed
above, consideration of costs to achieve MACT floor standards play no
part in our MACT floor determinations, but we nevertheless estimate
costs to the hazardous waste incinerator universe for administrative
purposes. We estimate that 35 hazardous waste incinerators, assuming no
market exit by any facility, will need to adopt measures to reduce
mercury emissions at their facilities by 3.46 Mg from the current
baseline of 4.4 Mg at an estimated annualized cost $12.2 million,
yielding a cost-effectiveness of $3.6 million per Mg of mercury
reduced.
b. What Are Our Beyond-the-Floor Considerations for Existing
Sources? As required by statute, we evaluated more stringent beyond-
the-floor controls for further reduction of mercury emissions from the
floor level. Activated carbon injection systems can achieve mercury
emission reductions of over 85 percent and we proposed them as beyond-
the-floor control in the April 1996 NPRM. In the May 1997 NODA, we
reevaluated the use of activated carbon injection 89 as
beyond-the-floor control, but cited significant cost-effectiveness
concerns. We reiterate these concerns here. Our technical support
document 90 provides details of annualized costs and
reductions that can be achieved.
---------------------------------------------------------------------------
\89\ Flue gas temperatures would be limited to 400 deg.F at the
point of carbon injection to enhance mercury removal.
\90\ USEPA, ``Technical Support Document for HWC MACT Standards,
Volume V: Emission Estimates and Engineering Costs,'' July 1999.
---------------------------------------------------------------------------
In addition, we considered a beyond-the-floor level of 50
g/dscm based on limiting the feedrate of mercury in the
hazardous waste (i.e., additional feedrate control beyond floor
control), and conducted an evaluation of the cost of achieving this
reduction to determine if this beyond-the-floor level would be
appropriate. The national incremental annualized compliance cost to
meet this beyond-the-floor level, rather than comply with the floor
controls, would be approximately $4.2 million for the entire hazardous
waste incinerator industry and would provide an incremental reduction
in mercury emissions nationally beyond the MACT floor controls of 0.7
Mg/yr, yielding a cost-effectiveness of $10 million per additional Mg
of mercury reduced. Thus, potential benefits in relation to costs are
disproportionately low, and we conclude that beyond-the-floor mercury
controls for hazardous waste incinerators are not warranted. Therefore,
we are not adopting a mercury beyond-the-floor standard.
Many commenters object to our beyond-the-floor standards as
proposed, citing high costs for achieving relatively small mercury
emission reductions, and compare the cost-effectiveness numbers with
regulations of other sources (electric utilities, municipal and medical
waste incinerators). Although comparison between rules for different
sources is not directly relevant (see, e.g., Portland Cement
Association v. Ruckelshaus 486 F.2d 375, 389 (D.C. Cir. 1973)), we
nevertheless agree that the cost of a mercury beyond-the-floor standard
in relation to benefits is substantial. Some commenters, as well as the
peer review panel, state that beyond-the-floor levels are not supported
by a need based on risk. Although the issue of residual risk can be
deferred under the CAA, an immediate question must be addressed if RCRA
regulation of air emissions is to be deferred. Our analysis \91\
indicates that mercury emissions at the floor level do not pose a
serious threat to the human health and environment and that these
standards are adequately protective to satisfy RCRA requirements as a
matter of national policy, subject, of course, to the possibility of
omnibus permit conditions for individual facilities in appropriate
cases.
---------------------------------------------------------------------------
\91\ USEPA, ``Risk Assessment Support to the Development of
Technical Standards for Emissions from Combustion Units Burning
Hazardous Wastes: Background Information Document,'' July 1999.
---------------------------------------------------------------------------
Some commenters state that the technical performance of activated
carbon injection for mercury control is not adequately proven.
Activated carbon injection performance has been adequately demonstrated
at several hazardous waste incinerators, municipal waste combustors,
and other devices.\92\ Our peer review panel also states that activated
carbon injection can achieve 85% reduction of mercury emissions.\93\
Some commenters also state that we underestimate the cost and
complexities of retrofitting incinerators to install activated carbon
injection systems (e.g., air reheaters would be required in many
cases). We reevaluated the modifications needed for retrofits of
activated carbon injection systems and have revised the costs of
installation.
---------------------------------------------------------------------------
\92\ USEPA, ``Technical Support Document for HWC MACT Standards,
Volume III: Selection of Proposed MACT Standards and Technologies,''
July 1999.
\93\ Memo from Mr. Shiva Garg, EPA to Docket No. F-96-RCSP-FFFFF
entitled ``Peer Review Panel Report in support of proposed rule for
revised standards for hazardous waste combustors'', dated August 5,
1996.
---------------------------------------------------------------------------
c. What Is the MACT Floor for New Sources? Floor control must be
based on the level of control used by the best controlled single
source. The best controlled source in our data base uses wet scrubbing
and hazardous waste feedrate control of mercury at a feedrate
corresponding to a maximum theoretical emission concentration of 0.072
g/dscm. We conclude that this feedrate is atypically low,
however, given that the next lowest mercury feedrates in our data base
are 63, 79, 110, and 130 g/dscm, expressed as maximum
theoretical emission concentrations. Accordingly, we select the mercury
feedrate for the second best controlled source under the aggregate
feedrate approach to represent the floor control mercury feedrate for
new sources. That feedrate is 110 g/dscm \94\ expressed as a
maximum theoretical emission concentration, and corresponds to an
emission level of 45 g/dscm after considering the expanded
MACT pool (i.e., the highest emission level from all sources using
floor control). Therefore, we establish a MACT floor level for mercury
for new sources of 45 g/dscm.\95\ We note that, at proposal
and in
[[Page 52864]]
the May 1997 NODA, mercury standards of 50 and 40 g/dscm
respectively were proposed for new sources. Today's final rule is in
the same range as those proposed emission levels.
---------------------------------------------------------------------------
\94\ The test conditions with mercury feedrates of 63 and 79
g/dscm do not have complete data sets for all metals and
chlorine. Thus, these conditions cannot be used under the aggregate
feedrate approach to define the floor level of feedrate control.
Mercury emissions from those test conditions are used, however, to
identify a floor emission level that is being achieved.
\95\ In addition, this floor emission level may be readily
achievable for new sources using activated carbon injection as floor
control for dioxiin/furan without the need for feedrate control of
mercury. Activated carbon injection can achieve mercury emissions
reductions of 85 percent. Given that the upper bound mercury
feedrate for ``normal'' wastes (i.e., without mercury spiking) in
our data base corresponds to a maximum theoretical emission
concentration of 300 g/dscm, such sources could achieve the
mercury floor emission level of 45 g/dscm using activated
carbon injection alone.
---------------------------------------------------------------------------
d. What Are Our Beyond-the-Floor Considerations for New Sources? We
evaluated the use of activated carbon injection as beyond-the-floor
control for new sources to achieve emission levels lower than floor
levels. In the April 1996 NPRM and May 1997 NODA, we stated that new
sources could achieve a beyond-the-floor level of 4 g/dscm
based on use of activated carbon injection. We cited significant cost-
effectiveness concerns at that level, however. We reiterate those
concerns today.
Many commenters object to our beyond-the-floor standards as
proposed, citing high costs for achieving relatively small mercury
emission reductions. They compare the proposed standards unfavorably
with other sources' regulations (e.g., electric utilities, municipal
and medical waste incinerators), where the cost-effectiveness values
are much lower. As stated earlier, comparison between rules for
different sources is not directly relevant. Nonetheless, we conclude
that use of activated carbon injection as a beyond-the-floor control
for mercury for new sources would not be cost-effective. We also note
that the floor levels are adequately protective to satisfy RCRA
requirements.
We also considered additional feedrate control of mercury as
beyond-the-floor control. We conclude, however, that significant
emission reductions using feedrate control may be problematic because
the detection limit of routine feedstream analysis procedures for
mercury is such that a beyond-the-floor mercury emission limit could be
exceeded even though mercury is not present in feedstreams at
detectable levels. Although sources could potentially perform more
sophisticated mercury analyses, cost-effectiveness considerations would
likely come into play and suggest that a beyond-the-floor standard is
not warranted.
4. What Are the Standards for Particulate Matter?
We establish standards for existing and new incinerators which
limit particulate matter emissions to 0.015 grains/dry standard cubic
foot (gr/dscf) or 34 milligrams per dry standard cubic meter (mg/
dscm).\96\ We chose the particulate matter standard as a surrogate
control for the metals antimony, cobalt, manganese, nickel, and
selenium. We refer to these five metals as ``nonenumerated metals''
because standards specific to each metal have not been established. We
discuss below the rationale for adopting these standards.
---------------------------------------------------------------------------
\96\ Particulate matter is a surrogate for the metal hazardous
air pollutants for which we are not establishing metal emission
standards: Antimony, cobalt, manganese, nickel, and selenium.
---------------------------------------------------------------------------
a. What Is the MACT Floor for Existing Sources? Our data base
consists of particulate matter emissions from 75 hazardous waste
incinerators that range from 0.0002 gr/dscf to 1.9 gr/dscf. Particle
size distribution greatly affects the uncontrolled particulate matter
emissions from hazardous waste incinerators, which, in turn, is
affected by incinerator type and design, particulate matter entrainment
rates, waste ash content, waste sooting potential and waste chlorine
content. Final emissions from the stacks of hazardous waste
incinerators are affected by the degree of control provided to
uncontrolled particulate matter emissions by the air pollution control
devices. Dry collection devices include fabric filters or electrostatic
precipitators, while wet collection devices include conventional wet
scrubbers (venturi type) or the newer patented scrubbers like
hydrosonic, free jet, or the collision type. Newer hazardous waste
incinerators now commonly use ionizing wet scrubbers or wet
electrostatic precipitators or a combination of both dry and wet
devices.
The MACT floor setting procedure involves defining MACT level of
control based on air pollution control devices used by the best
performing sources. Control devices used by these best performing
sources can be expected to routinely and consistently achieve superior
performance. Then, we identify an emissions level that well designed,
well-operated and well-maintained MACT controls can achieve based on
demonstrated performance, and engineering information and principles.
The average of the best performing 12 percent of hazardous waste
incinerators use either fabric filters, electrostatic precipitators
(dry or wet), or ionizing wet scrubbers (sometimes in combination with
venturi, packed bed, or spray tower scrubbers). As explained in Part
Four, Section V, we define floor control for particulate matter for
incinerators as the use of a well-designed, operated, and maintained
fabric filter, electrostatic precipitator, or ionizing wet scrubber.
Sources using certain wet scrubbing techniques such as high energy
venturi scrubbers, and novel condensation, free-jet, and collision
scrubbers can also have very low particulate matter emission levels. We
do not consider these devices to be MACT control, however, because, in
general, a fabric filter, electrostatic precipitator, or ionizing wet
scrubber will provide superior particulate matter control. In some
cases, sources using medium or low energy wet scrubbers are achieving
very low particulate matter emissions, but only for liquid waste
incinerators, which typically have low ash content waste. Thus, this
control technology demonstrates high effectiveness only under atypical
conditions, and we do not consider it to be MACT floor control for
particulate matter.
We conclude that fabric filters, electrostatic precipitators, and
ionizing wet scrubbers are routinely achieving an emission level of
0.015 gr/dscf based upon the following considerations:
i. Sources in our data base are achieving this emission level. Over
75 percent of the sources in the expanded MACT pool are achieving an
emission level of 0.015 gr/dscf. We investigated several sources in our
data base using floor control but failing to achieve this level, and we
found that the control devices do not appear to be well-designed,
operated, and maintained. Some of these sources are not using superior
fabric filter bags (e.g., Gore-tex, Nomex felt, or tri-lift
fabrics), some exhibit salt carry-over and entrainment from a poorly
operated wet scrubber located downstream of the fabric filter, and some
are poorly maintained in critical aspects (such as fabric cleaning
cycle or bag replacements). \97\
---------------------------------------------------------------------------
\97\ USEPA, ``Technical Support Document for HWC, MACT
Standards, Volume III: Selection of MACT Standards and
Technologies,'' July 1999.
---------------------------------------------------------------------------
ii. Well-designed, operated, and maintained fabric filters and
electrostatic precipitators can routinely achieve particulate matter
levels lower than the floor level of 0.015 gr/dscf. Levels less than
0.005 gr/dscf were demonstrated on hazardous waste incinerators and
municipal waste combustors in many cases. Well-designed fabric filters
have a surface collection area of over 0.5 ft2/acfm and high
performance filter fabrics such as Nomex and Gore-tex. Well-designed
electrostatic precipitators have advanced power system controls (with
intermittent or pulse energization), internal plate and electrode
geometry to
[[Page 52865]]
allow for high voltage potential, flue gas conditioning by addition of
water or reagents such as sulfur trioxide or ammonia to condition
particulate matter for lower resistivity, and optimized gas
distribution within the electrostatic precipitator. The technical
support document identifies many hazardous waste incinerators using
such well designed control equipment.
iii. The 0.015 gr/dscf level is well within the accepted
capabilities of today's particulate matter control devices in the
market place. Vendors typically guarantee emission levels for the
particulate matter floor control devices at less than 0.015 gr/dscf and
in some cases, as low as 0.005 gr/dscf.
iv. The 0.015 gr/dscf level is consistent with standards
promulgated for other incinerator source categories burning municipal
solid waste and medical waste, both of which are based on performance
of fabric filters or electrostatic precipitators as MACT. Comparison of
hazardous waste incinerator floor level to these standards is
appropriate because particulate matter characteristics such as particle
size distribution, loading and particulate matter type are comparable
within the above three types of waste burning source categories.
v. Hazardous waste incinerators that meet the 0.015 gr/dscf
particulate matter level also generally achieve semivolatile metal
system removal efficiencies of over 99% and low volatile metal system
removal efficiencies over 99.9%. This indicates superior particulate
matter collection efficiency because these metals are controlled by
controlling fine and medium-sized particulate matter.
vi. Over 50 percent of all test conditions in the data base,
regardless of the type of air pollution control device used, design of
the hazardous waste incinerator, or the type of waste burned, currently
meet the 0.015 gr/dscf level. This includes hazardous waste
incinerators with high particulate matter entrainment rates (such as
fluidized bed and rotary kilns) as well as those with wastes that
generate difficult to capture fine particulate matter, such as certain
liquid injection facilities.
vii. Many incinerators conducted several tests to develop the most
flexible operating envelope for day-to-day operations, keeping in view
the existing RCRA particulate matter standard of 0.08 gr/dscf. In many
test conditions, they elected to meet (and be limited to) the 0.015 gr/
dscf level, although they were only required to meet a 0.08 gr/dscf
standard.
Many commenters object to the use of engineering information and
principles in the selection of the MACT floor level. Some consider
engineering information and principles highly subjective and dependent
on reviewers' interpretation of the data, while others suggest the use
of accepted statistical methods for handling the data. We performed
analyses based on available statistical tools for outlier analysis and
variability, as discussed previously, but conclude that those
approaches are not appropriate. We continue to believe that the use of
engineering information and principles is a valid approach to establish
the MACT floor (i.e., to determine the level of performance
consistently achievable by properly designed and operated floor control
technology).
Some commenters object to the use of ``well-designed, operated and
maintained'' MACT controls. They consider the term too vague and want
specific parameters and features (e.g., air to cloth ratio for fabric
filters and power input for electrostatic precipitators) identified. We
understand commenters' concerns but such information is simply not
readily available. Further, many parameters work in relation with
several others making it problematic to quantify optimum values
separate from the other values. The system as a whole needs to be
optimized for best control efficiency on a case-by-case basis.
Some commenters object to our justification of particulate matter
achievability on the basis of vendors' claims. They contend that: (1)
Vendors' claims lack quality control and are driven by an incentive for
sales; (2) vendors' claims are based on normal operating conditions,
not on trial burn type conditions; and (3) MACT floor should not be
based on theoretical performance of state-of-the-art technology. We
would agree with the comments if the vendor information were from
advertising literature, but instead, our analysis was based on
warranties. The financial consequences of vendors' warranties require
those warranties to be conservative and based on proven performance
records, both during normal operations and during trial burn
conditions. In any case, we are using vendor information as
corroboration, not to establish a level of performance.
In the May 1997 NODA (62 FR at 24222), we requested comments on the
alternative MACT evaluation method based on defining medium and low
energy venturi-scrubbers burning low ash wastes as an additional MACT
control, but screening out facilities from the expanded MACT floor
universe that have poor semivolatile metal system removal efficiency.
The resulting MACT floor emission level under this approach would be
0.029 gr/dscf. Many commenters agree with the Agency that this
technique is unacceptable because it ignores a majority (over 75
percent) of the available particulate matter data in identifying the
MACT standard. This result is driven by the fact that corresponding
semivolatile metal data are not available from those sources. Other
commenters, however, suggest that venturi scrubbers should be
designated as MACT particulate matter control. These commenters suggest
that sources using venturi scrubbers are within the average of the best
performing 12 percent of sources, and there is no technical basis for
their exclusion. As stated above, we agree that well-designed and
operated venturi scrubbers can achieve the MACT floor level of 0.015gr/
dscf under some conditions (as when burning low ash wastes), but their
performance is generally not comparable to that of a fabric filter,
electrostatic precipitator, or ionizing wet scrubber. Thus, we conclude
that sources equipped with venturi scrubbers may not be able to achieve
the floor emission level in all cases, and the floor level would have
to be inappropriately increased to accommodate unrestricted use of
those units.
Some commenters state that we must demonstrate health or
environmental benefits if the rule were to require sources to replace
existing, less efficient air pollution control devices (e.g., venturi
scrubbers incapable of meeting the standard) with a better performing
device, particularly because particulate matter is not a hazardous air
pollutant under the CAA. These comments are not persuasive and are
misplaced as a matter of law. The MACT floor process was established
precisely to obviate such issues and to establish a minimum level of
control based on performance of superior air pollution control
technologies. Indeed, the chief motivation for adopting the technology-
based standards to control emissions of hazardous air pollutants in the
first instance was the evident failure of the very type of risk-based
approach to controlling air toxics as is suggested by the commenters.
(See, e.g., H. Rep. No. 490, 101st Cong. 2d Sess., at 318-19.) Inherent
in technology-based standard setting, of course, is the possibility
that some technologies will have to be replaced if they cannot achieve
the same level of performance as the best performing technologies.
Finally, with regard to the commenters' points regarding particulate
matter not being a hazardous air pollutant, we explain
[[Page 52866]]
above why particulate matter is a valid surrogate for certain hazardous
air pollutants, and can be used as a means of controlling hazardous air
pollutant emissions. In addition, the legislative history appears to
contemplate regulation of particulate matter as part of the MACT
process. (See S. Rep. No. 228, 101st Cong. 1st Sess., at
170.98)
---------------------------------------------------------------------------
\98\ Control of particulate matter also helps assure that the
standards are sufficiently protective to make RCRA regulation of
these sources' air emissions unnecessary (except potentially on a
site-specific basis through the omnibus permitting process). See
Technical Support Document on Risk Assessment.
---------------------------------------------------------------------------
We do not consider cost in selecting MACT floor levels.
Nevertheless, for purposes of administrative compliance with the
Regulatory Flexibility Act and various Executive Orders, we estimate
the cost burden on the hazardous waste incinerator universe to achieve
compliance. Approximately 38 percent of hazardous waste incinerators
currently meet the floor level of 0.015 gr/dscf. The annualized cost
for the remaining 115 incinerators to meet the floor level, assuming no
market exits, is estimated to be $17.4 million. Nonenumerated metals
and particulate matter emissions will be reduced nationally by 5.1 Mg/
yr and 1345 Mg/yr, respectively, or over 50 percent from current
baseline emissions.
b. What Are Our Beyond-the-Floor Considerations for Existing
Sources? In the NPRM, we proposed a beyond-the-floor emission level of
69 mg/dscm (0.030 gr/dscf) and solicited comment on an alternative
beyond-the-floor emission level of 34 mg/dscm (0.015 gr/dscf) based on
improved particulate matter control. (61 FR at 17383.) In the May 1997
NODA, we concluded that a beyond-the-floor standard may not be
warranted due to significant cost-effectiveness considerations. (62 FR
at 24222.)
In the final rule, we considered more stringent beyond-the-floor
controls that would provide additional reductions of particulate matter
emissions using fabric filters, electrostatic precipitators, and wet
ionizing scrubbers that are designed, operated, and maintained to have
improved collection efficiency. We considered a beyond-the-floor level
of 16 mg/dscm (0.007 gr/dscf), approximately one-half the floor
emission level, for existing incinerators based on improved particulate
matter control. We then determined the cost of achieving this reduction
in particulate matter, with corresponding reductions in the
nonenumerated metals for which particulate matter is a surrogate, to
determine if this beyond-the-floor level would be appropriate. The
national incremental annualized compliance cost for incinerators to
meet this beyond-the-floor level, rather than comply with the floor
controls, would be approximately $6.8 million for the entire hazardous
waste incinerator industry and would provide an incremental reduction
in nonenumerated metals emissions nationally beyond the MACT floor
controls of 1.7 Mg/yr. Based on these costs of approximately $4.1
million per additional Mg of nonenumerated metals emissions removed, we
conclude that this beyond-the-floor option for incinerators is not
acceptably cost-effective nor otherwise justified. Therefore, we do not
adopt this beyond-the-floor standard. Poor cost-effectiveness would be
particularly unacceptable here considering that these metals also have
relatively low toxicity. Thus, the particulate matter standard for new
incinerators is 34 mg/dscm. Therefore, the cost-effectiveness threshold
we would select would be less than for more toxic pollutants such as
dioxin, mercury or other metals.
c. What Is the MACT Floor for New Sources? We proposed a floor
level of 0.030 gr/dscf for new sources based on the best performing
source in the data base, which used a fabric filter with an air-to-
cloth ratio of 3.8 acfm/ft\2\. In the May 1997 NODA, we reevaluated the
particulate matter floor level and indicated that floor control for
existing sources would also appear to be appropriate for new sources.
We are finalizing the approach discussed in the May 1997 NODA whereby
floor control is a well-designed, operated, and maintained fabric
filter, electrostatic precipitator, or ionizing wet scrubber, and the
floor emission level is 0.015 gr/dscf.
d. What Are Our Beyond-the-Floor Considerations for New Sources? We
considered more stringent beyond-the-floor controls that would provide
additional reductions of particulate matter emissions using fabric
filters, electrostatic precipitators, and wet ionizing scrubbers that
are designed, operated, and maintained to have improved collection
efficiency. We considered a beyond-the-floor level of 16 mg/dscm (0.007
gr/dscf), approximately one-half the emissions level for existing
sources, for new incinerators based on improved particulate matter
control. For analysis purposes, improved particulate matter control
assumes the use of higher quality fabric filter bag material. We then
determined the cost of achieving this reduction in particulate matter,
with corresponding reductions in the nonenumerated metals for which
particulate matter is a surrogate, to determine if this beyond-the-
floor level would be appropriate. The incremental annualized compliance
cost for one new large incinerator to meet this beyond-the-floor level,
rather than comply with floor controls, would be approximately $39,000
and would provide an incremental reduction in nonenumerated metals
emissions of approximately 0.05 Mg/yr.99 For a new small
incinerator, the incremental annualized compliance cost would be
approximately $7,500 and would provide an incremental reduction in
nonenumerated metals emissions of approximately 0.008 Mg/yr. Based on
these costs of approximately $0.8-1.0 million per additional Mg of
nonenumerated metals removed, we conclude that a beyond-the-floor
standard of 16 mg/dscm is not warranted due to the high cost of
compliance and relatively small nonenumerated metals emission
reductions. Poor cost-effectiveness would be particularly unacceptable
here considering that these metals also have relatively low toxicity.
Thus, the particulate matter standard for new incinerators is 34 mg/
dscm.
---------------------------------------------------------------------------
\99\ Based on the data available, the average emissions in sum
of the five nonenumerated metals from incinerators using MACT
particulate matter control is approximately 229 g/dscm. To
estimate emission reductions of the nonenumerated metals for
specific test conditions, we assume a linear relationship between a
reduction in particulate matter and these metals.
---------------------------------------------------------------------------
5. What Are the Standards for Semivolatile Metals?
Semivolatile metals are comprised of lead and cadmium. We establish
standards which limit semivolatile metal emissions to 240 g/
dscm for existing sources and 24 g/dscm for new sources. We
discuss below the rationale for adopting these standards.
a. What Is the MACT Floor for Existing Sources? As discussed in
Part Four, Section V of the preamble, floor control for semivolatile
metals is hazardous waste feedrate control of semivolatile metals plus
MACT floor particulate matter control. We use the aggregate feedrate
approach to define the level of semivolatile metal feedrate control. We
have aggregate feedrate data for 20 test conditions from nine hazardous
waste incinerators that are using MACT floor control for particulate
matter. The semivolatile metal feedrate levels, expressed as maximum
theoretical emission concentrations, for these sources range from 100
g/dscm to 1.5 g/dscm while the semivolatile emissions range
from 1 to 6,000 g/dscm. The MACT-defining maximum theoretical
emission concentration is
[[Page 52867]]
5,300 g/dscm. Upon expanding the MACT pool, only the highest
emissions test condition of 6,000 g/dscm was screened out
because the semivolatile metal maximum theoretical emission
concentration for this test condition was higher than the MACT-defining
maximum theoretical emission concentration. The highest emission test
condition in the remaining expanded MACT pool identifies a MACT floor
emission level of 240 g/dscm.
We originally proposed a semivolatile metal floor standard of 270
g/dscm based on semivolatile metal feedrate control. We
subsequently refined the emissions data base and reevaluated the floor
methodology, and discussed in the May 1997 NODA a semivolatile metal
floor level of 100 g/dscm. Commenters express serious concerns
with the May 1997 NODA approach in two areas. First, they note that the
MACT-defining best performing sources have very low emissions, not
entirely due to the performance of MACT control, but also due to
atypically low semivolatile metal feedrates. Second, they object to our
use of a ``breakpoint'' analysis to screen out the outliers from the
expanded MACT pool (which was already small due to the screening
process to define the feedrate level representative of MACT control).
Our final methodology makes adjustments to address these concerns.
Under the aggregate feedrate approach, sources with atypically low
feedrates of semivolatile metals would not necessarily drive the floor
control feedrate level. This is because the aggregate feedrate approach
identifies as the best performing sources (relative to feedrate
control) those with low feedrates in the aggregate for all metals and
chlorine. In addition, the floor methodology no longer uses the
breakpoint approach to identify sources not using floor control. These
issues are discussed above in detail in Part Four, Section V, of the
preamble.
Although cost-effectiveness of floor emission levels is not a
factor in defining floor control or emission levels, we have estimated
compliance costs and emissions reductions at the floor for
administrative purposes. Approximately 66 percent of sources currently
meet the semivolatile metal floor level of 240 g/dscm. The
annualized cost for the remaining 64 incinerators to meet the floor
level, assuming no market exits, is estimated to be $1.8 million.
Semivolatile metal emissions will be reduced nationally by 55.9 Mg per
year from the baseline emissions level of 58.5 Mg per year, a reduction
of 95.5%.
b. What Are Our Beyond-the-Floor Considerations for Existing
Sources? We considered more stringent semivolatile metal feedrate
control as a beyond-the-floor control to provide additional reductions
in emissions. Cost effectiveness considerations would likely come into
play, however, and suggest that a beyond-the-floor standard is not
warranted. Therefore, we conclude that a beyond-the-floor standard for
semivolatile metals for existing sources is not appropriate. We note
that a beyond-the-floor standard is not needed to meet our RCRA
protectiveness mandate.
c. What Is the MACT Floor for New Sources? Floor control for new
sources is: (1) The level of semivolatile metal feedrate control used
by the source with the lowest aggregate feedrate for all metals and
chlorine;100 and (2) use of MACT floor particulate matter
control for new sources (i.e., a fabric filter, electrostatic
precipitator, or wet ionizing scrubber achieving a particulate matter
emission level of 0.015 gr/dscf). Three sources in our data base are
currently using the floor control selected for all new sources and are
achieving semivolatile emissions ranging from 2 g/dscm to 24
g/dscm. To ensure that the floor level is achievable by all
sources using floor control, we are establishing the floor level for
semivolatile metals for new sources at 24 g/dscm.
---------------------------------------------------------------------------
\100\ I.e., a semivolatile metal feedrate equivalent to a
maximum theoretical emission concentration of 3,500 g/dscm.
---------------------------------------------------------------------------
d. What Are Our Beyond-the-Floor Considerations for New Sources? We
considered more stringent beyond-the-floor controls (i.e., a more
restrictive semivolatile metal feedrate) to provide additional
reduction in emissions. We determined that cost-effectiveness
considerations would likely be unacceptable due to the relatively low
concentrations achieved at the floor. This suggests that a beyond-the-
floor standard is not warranted. We note that a beyond-the-floor
standard is not needed to meet our RCRA protectiveness mandate.
6. What Are the Standards for Low Volatile Metals?
Low volatile metals are comprised of arsenic, beryllium, and total
chromium. We establish standards that limit emissions of these metals
to 97 g/dscm for both existing and new incinerators. We
discuss below the rationale for adopting these standards.
a. What Is the MACT Floor for Existing Sources? We are using the
same approach for low volatile metals as we did for semivolatile metals
to define floor control. Floor control for low volatile metals is use
of particulate matter floor control and control of the feedrate of low
volatile metals to a level identified by the aggregate feedrate
approach.
The low volatile metal feedrates for sources using particulate
matter floor control range from 300 g/dscm to 1.4 g/dscm when
expressed as maximum theoretical emission concentrations. Emission
levels for these sources range from 1 to 803 g/dscm.
Approximately 60 percent of sources using particulate matter floor
control have low volatile metal feedrates below the MACT floor
feedrate--24,000 g/dscm, expressed as a maximum theoretical
emission concentration.
Upon expanding the MACT pool, the source using floor control with
the highest emissions is achieving an emission level of 97 g/
dscm. Accordingly, we are establishing the floor level for low volatile
metals for existing sources at 97 g/dscm to ensure that the
floor level is achievable by all sources using floor control.
We identified a low volatile metal floor level of 210 g/
dscm in the April 1996 proposal. The refined data analysis in the May
1997 NODA, based on the revised data base, reduced the low volatile
metal floor level to 55 g/dscm. As with semivolatile metals,
commenters express serious concerns with the May 1997 NODA approach,
including selection of the breakpoint ``outlier'' screening approach
and use of hazardous waste incinerator data with atypically low
feedrates for low volatile metals. We acknowledge those concerns and
adjusted our methodology accordingly. See discussions above in Part
Four, Section V.
We estimated compliance costs to the hazardous waste incinerator
universe for administrative purposes. Approximately 63 percent of
incinerators currently meet the 97 g/dscm floor level. The
annualized cost for the remaining 69 incinerators to meet the floor
level, assuming no market exits, is estimated to be $1.9 million, and
would reduce low volatile metal emissions nationally by 6.9 Mg per year
from the baseline emissions level of 8 Mg per year.
b. What Are Our Beyond-the-Floor Considerations for Existing
Sources? We considered more stringent beyond-the-floor controls (i.e.,
a more restrictive low volatile metal feedrate) to provide additional
reduction in emissions. Due to the relatively low concentrations
achieved at the floor, we determined that cost-effectiveness
considerations would likely be unacceptable. Therefore, we conclude
that a beyond-the-floor standard for low volatile metals for existing
sources is not
[[Page 52868]]
appropriate. We note that a beyond-the-floor standard is not needed to
meet our RCRA protectiveness mandate.
c. What Is the MACT Floor for New Sources? We identified a floor
level of 260 g/dscm for new sources at proposal based on the
best performing source in the data base. That source uses a venturi
scrubber with a low volatile metal feedrate equivalent to a maximum
theoretical emission concentration of 1,000 g/dscm. Our
reevaluation of the data base in the May 1997 NODA identified a floor
level of 55 g/dscm based on use of floor control for
particulate matter and feedrate control of low volatile metals. Other
than the comments on the two issues of low feedrate and the
inappropriate use of a breakpoint analysis discussed above, no other
significant comments challenged this floor level.
Floor control for new sources is the same as discussed in the May
1997 NODA (i.e., use of particulate matter floor control and feedrate
control of low volatile metals), except the floor feedrate level under
the aggregate feedrate approach used for today's final rule is 13,000
g/dscm. Upon expanding the MACT pool, the source using floor
control with the highest emissions is achieving an emission level of 97
g/dscm.101 Accordingly, we are establishing the
floor level for low volatile metals for new sources at 97 g/
dscm to ensure that the floor level is achievable by all sources using
floor control.
---------------------------------------------------------------------------
\101\ The emission level for new sources achieving a feedrate
control of 13,000 g/dscm (expressed as a maximum
theoretical emission concentration) is the same as the emission
level for existing sources achieving a feedrate control of 24,000
g/dscm because sources feeding low volatile metals in the
range of 13,000 to 24,000 g/dscm have emission levels at or
below 97 g/dscm. Although these sources feel low volatile
metals at higher levels than the single best feedrate-controlled
source, their emission control devices apparently are more
efficient. Thus, they achieved lower emissions than the single best
feedrate-controlled source.
---------------------------------------------------------------------------
d. What Are Our Beyond-the-Floor Considerations for New Sources? We
considered more stringent beyond-the-floor controls (i.e., a more
restrictive low volatile metal feedrate) to provide additional
reduction in emissions. Because of the relatively low concentrations
achieved, we determined that cost-effectiveness considerations would
likely be unacceptable. Therefore, we conclude that a beyond-the-floor
standard for low volatile metals for new sources is not appropriate. We
note that a beyond-the-floor standard is not needed to meet our RCRA
protectiveness mandate.
7. What Are the Standards for Hydrochloric Acid and Chlorine Gas?
We establish standards for hydrochloric acid and chlorine gas,
combined, for existing and new incinerators of 77 and 21 ppmv
respectively. We discuss below the rationale for adopting these
standards.
a. What Is the MACT Floor for Existing Sources? Almost all
hazardous waste incinerators currently use some type of add-on stack
gas wet scrubbing system, in combination with control of the feedrate
of chlorine, to control emissions of hydrochloric acid and chlorine
gas. A few sources use dry or semi-dry scrubbing, alone or in
combination with wet scrubbing, while a few rely upon feedrate control
only. Wet scrubbing consistently provides a system removal efficiency
of over 99 percent for various scrubber types and configurations.
Current RCRA regulations require 99% removal efficiency and most
sources are achieving greater than 99.9 percent removal efficiency.
Accordingly, floor control is defined as wet scrubbing achieving a
system removal efficiency of 99 percent or greater combined with
feedrate control of chlorine.
The floor feedrate control level for chlorine is 22 g/
dscm, expressed as a maximum theoretical emission concentration, based
on the aggregate feedrate approach. The source in the expanded MACT
pool (i.e., all sources using floor control) with the highest emission
levels of hydrogen chloride and chlorine gas is achieving an emission
level of 77 ppmv. Thus, MACT floor for existing sources is 77 ppmv.
At proposal, we also defined floor control as wet scrubbing
combined with feedrate control of chlorine. We proposed a floor
emission level of 280 ppmv based on a chlorine feedrate control level
of 21 g/dscm, expressed as a maximum theoretical emission
concentration. The best performing sources relative to emission levels
all use wet scrubbing and feed chlorine at that feedrate or lower. We
identified a floor level of 280 ppmv based on all sources in our data
base using floor control and after applying a statistically-derived
emissions variability factor. In the May 1997 NODA, we again defined
floor control as wet (or dry) scrubbing with feedrate control of
chlorine. We discussed a floor emission level of 75 ppmv based on the
revised data base and break-point floor methodology. Rather than using
a break-point analysis in the final rule, we use a floor methodology
that identifies floor control as an aggregate chlorine feedrate
combined with scrubbing that achieves a removal efficiency of at least
99 percent.
We estimated compliance costs to the hazardous waste incinerator
universe for administrative purposes. Approximately 70 percent of
incinerators currently meet the hydrochloric acid and chlorine gas
floor level of 77 ppmv. The annualized cost for the remaining 57
incinerators to meet that level, assuming no market exits, is estimated
to be $4.75 million and would reduce emissions of hydrochloric acid and
chlorine gas nationally by 2,670 Mg per year from the baseline
emissions level of 3410 Mg per year, a reduction of 78%.
b. What Are Our Beyond-the-Floor Considerations for Existing
Sources? We considered more stringent beyond-the-floor controls to
provide additional reduction in emissions. Due to the relatively low
concentrations achieved at the floor, we determined that cost-
effectiveness considerations would likely be unacceptable. Therefore,
we conclude that a beyond-the-floor standard for hydrochloric acid and
chlorine gas for existing sources is not appropriate. We note that a
beyond-the-floor standard is not needed to meet our RCRA protectiveness
mandate.
c. What Is the MACT Floor for New Sources? We identified a floor
level of 280 ppmv at proposal based on the best performing source in
the data base. That source uses wet scrubbing and a chlorine feedrate
of 17 g/dscm, expressed as a maximum theoretical emission
concentration. Our reevaluation of the revised data base in the May
1997 NODA defined a floor level of 75 ppmv. Based on the aggregate
feedrate approach used for today's final rule, we are establishing a
floor level of 21 ppmv, based on a chlorine feedrate of 4.7 g/
dscm expressed as a maximum theoretical emission concentration.
d. What Are Our Beyond-the-Floor Considerations for New Sources? We
considered more stringent beyond-the-floor controls to provide
additional reduction in emissions. Due to the relatively low
concentrations achieved at the floor, we determined that cost-
effectiveness considerations would likely be unacceptable. Therefore,
we conclude that a beyond-the-floor standard for hydrochloric acid and
chlorine gas for new sources is not appropriate. We note that a beyond-
the-floor standard is not needed to meet our RCRA protectiveness
mandate.
8. What Are the Standards for Carbon Monoxide?
We use carbon monoxide as a surrogate for organic hazardous air
pollutants. Low carbon monoxide
[[Page 52869]]
concentrations in stack gas are an indicator of good control of organic
hazardous air pollutants and are achieved by operating under good
combustion practices.
We establish carbon monoxide standards of 100 ppmv for both
existing and new sources based on the rationale discussed below.
Sources have the option to comply with either the carbon monoxide or
the hydrocarbon emission standard. Sources that elect to comply with
the carbon monoxide standard must also document compliance with the
hydrocarbon standard during the performance test to ensure control of
organic hazardous air pollutants. See discussion in Part Four, Section
IV.B.
a. What Is the MACT Floor for Existing Sources? As proposed, floor
control for existing sources is operating under good combustion
practices (e.g., providing adequate excess oxygen; providing adequate
fuel (waste) and air mixing; maintaining high temperatures and adequate
combustion gas residence time at those temperatures).102
Given that there are many interdependent parameters that affect
combustion efficiency and thus carbon monoxide emissions, we were not
able to quantify ``good combustion practices.''
---------------------------------------------------------------------------
\102\ USEPA, ``Technical Support Document for HWC MACT
Standards, Volume III: Selection of MACT Standards and
Technologies,'' July 1999.
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We are identifying a floor level of 100 ppmv on an hourly rolling
average, as proposed, because it is being achieved by sources using
good combustion practices. More than 80 percent of test conditions in
our data base have carbon monoxide levels below 100 ppmv, and more than
60 percent have levels below 20 ppmv. Of approximately 20 test
conditions with carbon monoxide levels exceeding 100 ppmv, we know the
characteristics of many of these sources are not representative of good
combustion practices (e.g., use of rotary kilns without afterburners;
liquid injection incinerators with rapid combustion gas quenching). In
addition, we currently limit carbon monoxide concentrations for
hazardous waste burning boilers and industrial furnaces to 100 ppmv to
ensure good combustion conditions and control of organic toxic
compounds. Finally, we have established carbon monoxide limits in the
range of 50 to 150 ppmv on other waste incineration sources (i.e.,
municipal waste combustors, medical waste incinerators) to ensure good
combustion conditions. We are not aware of reasons why it may be more
difficult for a hazardous waste incinerator to achieve carbon monoxide
levels of 100 ppmv.
We estimated compliance costs to the hazardous waste incinerator
universe for administrative purposes. Because carbon monoxide emissions
from these sources are already regulated under RCRA, approximately 97
percent of incinerators currently meet the floor level of 100 ppmv. The
annualized cost for the remaining six incinerators to meet the floor
level, assuming no market exits, is estimated to be $0.9 million and
would reduce carbon monoxide emissions nationally by 45 Mg per year
from the baseline emissions level of 9170 Mg per year.103
Although we cannot quantify a corresponding reduction of organic
hazardous air pollutant emissions, we estimate these reductions would
be significant based on the carbon monoxide reductions.
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\103\ As discussed previously in the text, you have the option
of complying with the hydrocarbon emission standard rather than the
carbon monoxide standard. This is because carbon monoxide is a
conservative indicator of the potential for emissions of organic
compounds while hydrocarbon concentrations in stack gas are a direct
measure of emissions of organic compounds.
---------------------------------------------------------------------------
b. What Are Our Beyond-the-Floor Considerations for Existing
Sources? We considered more stringent beyond-the-floor controls (i.e.,
better combustion practices resulting in lower carbon monoxide levels)
to provide additional reduction in emissions. Although it is difficult
to quantify the reduction in emissions of organic hazardous air
pollutants that would be associated with a lower carbon monoxide limit,
we concluded that cost-effectiveness considerations would likely come
into play, and suggest that a beyond-the-floor standard is not
warranted. Therefore, we conclude that a beyond-the-floor standard for
carbon monoxide for existing sources is not appropriate. We note that,
although control of carbon monoxide (or hydrocarbon) is not an absolute
guarantee that nondioxin/furan products of incomplete combustion will
not be emitted at levels of concern, this problem (where it may exist)
can be addressed through the RCRA omnibus permitting process.
c. What Is the MACT Floor for New Sources? At proposal and in the
May 1997 NODA, we stated that operating under good combustion practices
defines MACT floor control for new (and existing)
sources,104 and the preponderance of data indicate that a
floor level of 100 ppmv over an hourly rolling average is readily
achievable. For reasons set forth in the proposal, and absent data to
the contrary, we conclude that this floor level is appropriate.
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\104\ Because we cannot quantify good combustion practices,
floor control for the single best controlled source is the same as
for existing sources (i.e., that combination of design, operation,
and maintenance that achieves good combustion as evidenced by carbon
monoxide levels of 100 ppmv or less on an hourly rolling average).
---------------------------------------------------------------------------
d. What Are Our Beyond-the-Floor Considerations for New Sources? We
considered more stringent beyond-the-floor controls (i.e., better
combustion practices resulting in lower carbon monoxide levels) to
provide additional reduction in emissions. For the reasons discussed
above in the context of beyond-the-floor controls for existing sources,
however, we conclude that a beyond-the-floor standard for carbon
monoxide for new sources is not appropriate.
9. What Are the Standards for Hydrocarbon?
Hydrocarbon concentrations in stack gas are a direct surrogate for
emissions of organic hazardous pollutants. We establish hydrocarbon
standards of 10 ppmv for both existing and new sources based on the
rationale discussed below. Sources have the option to comply with
either the carbon monoxide or the hydrocarbon emission standard.
Sources that elect to comply with the carbon monoxide standard,
however, must nonetheless document compliance with the hydrocarbon
standard during the comprehensive performance test.
a. What Is the MACT Floor for Existing Sources? We proposed a
hydrocarbon emission standard of 12 ppmv 105 based on good
combustion practices, but revised it in the May 1997 NODA to 10 ppmv
based on refinements of analysis and the corrected data base.
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\105\ Based on an hourly rolling average, reported as propane,
corrected to 7 percent oxygen, dry basis.
---------------------------------------------------------------------------
As proposed, floor control for existing sources is operating under
good combustion practices (e.g., providing adequate excess oxygen;
providing adequate fuel (waste) and air mixing; maintaining high
temperatures and adequate combustion gas residence time at those
temperatures). Given that there are many interdependent parameters that
affect combustion efficiency and thus hydrocarbon emissions, we are not
able to quantify good combustion practices.
We are identifying a floor level for the final rule of 10 ppmv on
an hourly rolling average because it is being achieved using good
combustion practices. More than 85 percent of test conditions in our
data base have hydrocarbon levels below 10 ppmv, and nearly 75 percent
have levels below 5 ppmv. Although 13 test conditions in our data base
representing 7 sources have hydrocarbon levels higher than 10 ppmv, we
conclude that these sources
[[Page 52870]]
are not operating under good combustion practices. For example, one
source is a rotary kiln without an afterburner. Another source is a
fluidized bed type incinerator that operates at lower than typical
combustion temperatures without an afterburner while another source is
operating at high carbon monoxide levels, indicative of poor combustion
efficiency.106
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\106\ USEPA, ``Technical Support Document for HWC MACT
Standards, Volume III: Selection of MACT Standards and
Technologies,'' July 1999.
---------------------------------------------------------------------------
Some commenters on the May 1997 NODA object to the 10 ppmv level
and suggest adopting a level of 20 ppmv based on the BIF rule
(Sec. 266.104(c)), and an earlier hazardous waste incinerator proposal
(55 FR 17862 (April 27, 1990)). These commenters cite sufficient
protectiveness at the 20 ppmv level. We conclude that this comment is
not on point because the MACT standards are technology rather than
risk-based. The MACT standards must reflect the level of control that
is not less stringent than the level of control achieved by the best
performing sources. Because hazardous waste incinerators are readily
achieving a hydrocarbon level of 10 ppmv using good combustion
practices, that floor level is appropriate.
Some commenters also object to the requirement to use heated flame
ionization hydrocarbon detectors 107 in hazardous waste
incinerators that use wet scrubbers. The commenters state that these
sources have a very high moisture content in the flue gas that hinders
proper functioning of the specified hydrocarbon detectors. We agree
that hydrocarbon monitors may be hindered in these situations. For this
and other reasons (e.g., some sources can have high carbon monoxide but
low hydrocarbon levels), the final rule gives sources the option of:
(1) Continuous hydrocarbon monitoring; or (2) continuous carbon
monoxide monitoring and demonstration of compliance with the
hydrocarbon standard only during the performance test.
---------------------------------------------------------------------------
\107\ See Performance Specification 8A, appendix B, part 60,
``Specifications and test procedures for carbon monoxide and oxygen
continuous monitoring systems in stationary sources.''
---------------------------------------------------------------------------
We estimated compliance costs to the hazardous waste incinerator
universe for administrative purposes. Approximately 97 percent of
incinerators currently meet the hydrocarbon floor level of 10 ppmv. The
annualized cost for the remaining six incinerators to meet the floor
level, assuming no market exits, is estimated to be $0.35 million, and
would reduce hydrocarbon emissions nationally by 28 Mg per year from
the baseline emissions level of 292 Mg per year. Although the
corresponding reduction of organic hazardous air pollutant emissions
cannot be quantified, these reductions are qualitatively assessed as
significant.
b. What Are Our Beyond-the-Floor Considerations for Existing
Sources? We considered more stringent beyond-the-floor controls (i.e.,
better combustion practices resulting in lower hydrocarbon levels) to
provide additional reduction in emissions. Although it is difficult to
quantify the reduction in emissions of organic hazardous air pollutants
that would be associated with a lower hydrocarbon limit, cost-
effectiveness considerations would likely come into play, however, and
suggest that a beyond-the-floor standard is not warranted. Therefore,
we conclude that a beyond-the-floor standard for hydrocarbon emissions
for existing sources is not appropriate. We note further that, although
control of hydrocarbon emissions is not an absolute guarantee that
nondioxin products of incomplete combustion will not be emitted at
levels of concern, this problem (where it may exist) can be addressed
through the RCRA omnibus permitting process.
c. What Is the MACT Floor for New Sources? At proposal and in the
May 1997 NODA, we stated that operation under good combustion practices
at new (and existing) hazardous waste incinerators defines the MACT
control.108 As discussed above, sources using good
combustion practices are achieving hydrocarbon levels of 10 ppmv or
below. Comments on this subject were minor and did not identify any
problems in achieving the 10 ppmv level by new sources. Thus, we
conclude that a floor level of 10 ppmv on hourly rolling average is
appropriate for new sources.
---------------------------------------------------------------------------
\108\ Because we cannot quantify good combustion practices,
floor control for the single best controlled soruce is the same as
for existing sources (i.e., that combination of design, operation,
and maintenance that achieves good combustion as evidenced by
hydrocarbon levels of 10 ppmv or less on an hourly rolling average).
---------------------------------------------------------------------------
d. What Are Beyond-the-Floor Considerations for New Sources? We
considered more stringent beyond-the-floor controls (i.e., better
combustion practices) to provide additional reduction in emissions. For
the reasons discussed above in the context of beyond-the-floor controls
for existing sources, however, we conclude that a beyond-the-floor
standard for hydrocarbons for new sources is not appropriate.
10. What Are the Standards for Destruction and Removal Efficiency?
We establish a destruction and removal efficiency (DRE) standard
for existing and new incinerators to control emissions of organic
hazardous air pollutants other than dioxins and furans. Dioxins and
furans are controlled by separate emission standards. See discussion in
Part Four, Section IV.A. The DRE standard is necessary, as previously
discussed, to complement the carbon monoxide and hydrocarbon emission
standards, which also control these hazardous air pollutants.
The standard requires 99.99 percent DRE for each principal organic
hazardous constituent (POHC), except that 99.9999 percent DRE is
required if specified dioxin-listed hazardous wastes are burned. These
wastes are listed as--F020, F021, F022, F023, F026, and F027--RCRA
hazardous wastes under Part 261 because they contain high
concentrations of dioxins.
a. What Is the MACT Floor for Existing Sources? Existing sources
are currently subject to DRE standards under Sec. 264.342 and
Sec. 264.343(a) that require 99.99 percent DRE for each POHC, except
that 99.9999 percent DRE is required if specified dioxin-listed
hazardous wastes are burned. Accordingly, these standards represent
MACT floor. Since all hazardous waste incinerators are currently
subject to these DRE standards, they represent floor control, i.e.,
greater than 12 percent of existing sources are achieving these
controls.
b. What Are Our Beyond-the-Floor Considerations for Existing
Sources? Beyond-the-floor control would be a requirement to achieve a
higher percentage DRE, for example, 99.9999 percent DRE for POHCs for
all hazardous wastes. A higher DRE could be achieved by improving the
design, operation, or maintenance of the combustion system to achieve
greater combustion efficiency.
Sources will not incur costs to achieve the 99.99 percent DRE floor
because it is an existing RCRA standard. A substantial number of
existing incinerators are not likely to be routinely achieving 99.999
percent DRE, however, and most are not likely to be achieving 99.9999
percent DRE. Improvements in combustion efficiency will be required to
meet these beyond-the-floor DREs. Improved combustion efficiency is
accomplished through better mixing, higher temperatures, and longer
residence times. As a practical matter, most combustors are mixing-
limited. Thus, improved mixing is
[[Page 52871]]
necessary for improved DREs. For a less-than-optimum burner, a certain
amount of improvement may typically be accomplished by minor,
relatively inexpensive combustor modifications--burner tuning
operations such as a change in burner angle or an adjustment of swirl--
to enhance mixing on the macro-scale. To achieve higher and higher
DREs, however, improved mixing on the micro-scale may be necessary
requiring significant, energy intensive and expensive modifications
such as burner redesign and higher combustion air pressures. In
addition, measurement of such DREs may require increased spiking of
POHCs and more sensitive stack sampling and analysis methods at added
expense.
Although we have not quantified the cost-effectiveness of a beyond-
the-floor DRE standard, we do not believe that it would be cost-
effective. For reasons discussed above, we believe that the cost of
achieving each successive order-of-magnitude improvement in DRE will be
at least constant, and more likely increasing. Emissions reductions
diminish substantially, however, with each order of magnitude
improvement in DRE. For example, if a source were to emit 100 gm/hr of
organic hazardous air pollutants assuming zero DRE, it would emit 10
gm/hr at 90 percent DRE, 1 gm/hr at 99 percent DRE, 0.1 gm/hr at 99.9
percent DRE, 0.01 gm/hr at 99.99 percent DRE, and 0.001 gm/hr at 99.999
percent DRE. If the cost to achieve each order of magnitude improvement
in DRE is roughly constant, the cost-effectiveness of DRE decreases
with each order of magnitude improvement in DRE. Consequently, we
conclude that this relationship between compliance cost and diminished
emissions reductions associated with a more stringent DRE standard
suggests that a beyond-the-floor standard is not warranted.
c. What Is the MACT Floor for New Sources? The single best
controlled source, and all other hazardous waste incinerators, are
subject to the existing RCRA DRE standard under Sec. 264.342 and
Sec. 264.343(a). Accordingly, we adopt this standard as the MACT floor
for new sources.
d. What Are Our Beyond-the-Floor Considerations for New Sources? As
discussed above, although we have not quantified the cost-effectiveness
of a more stringent DRE standard, diminishing emissions reductions with
each order of magnitude improvement in DRE suggests that cost-
effectiveness considerations would likely come into play. We conclude
that a beyond-the-floor standard is not warranted.
VII. What Are the Standards for Hazardous Waste Burning Cement Kilns?
A. To Which Cement Kilns Do Today's Standards Apply?
The standards promulgated today apply to each existing,
reconstructed, and newly constructed Portland cement manufacturing kiln
that burns hazardous waste. These standards apply to all hazardous
waste burning cement kilns (both major source and area source cement
plants). Portland cement kilns that do not engage in hazardous waste
burning operations are not subject to this NESHAP. However, these
hazardous waste burning kilns would be subject to the NESHAP for other
sources of hazardous air pollutants at the facility (e.g., clinker
cooler stack) that we finalized in June 1999.109
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\109\ On June 14, 1999, we promulgated regulations for kiln
stack emissions for nonhazardous waste burning cement kilns and
other sources of hazardous air pollutants at all Portland
manufacturing plants. (See 64 FR 31898.)
---------------------------------------------------------------------------
B. How Did EPA Initially Classify Cement Kilns?
1. What Is the Basis for a Separate Class Based on Hazardous Waste
Burning?
Portland cement manufacturing is one of the initial 174 categories
of major and area sources of hazardous air pollutants listed pursuant
to section 112(c)(1) for which section 112(d) standards are to be
established.110 We divided the Portland cement manufacturing
source category into two different classes based on whether the cement
kiln combusts hazardous waste. This action was taken for two principal
reasons: If hazardous wastes are burned in the kiln, emissions of
hazardous air pollutants can be different for the two types of kilns in
terms of both types and concentrations of hazardous air pollutants
emitted, and metals and chlorine emissions are controlled in a
significantly different manner.
---------------------------------------------------------------------------
\110\ EPA published an initial list of 174 categories of area
and major sources in the Federal Register on July 16, 1992. (See 57
FR at 31576.)
---------------------------------------------------------------------------
A comparison of metals levels in coal and in hazardous waste fuel
burned in lieu of coal on a heat input basis reveals that hazardous
waste frequently contains higher concentrations of hazardous air
pollutant metals (i.e., mercury, semivolatile metals, low volatile
metals) than coal. Hazardous waste contains higher levels of
semivolatile metals than coal by more than an order of magnitude at
every cement kiln in our data base.111 In addition, coal
concentrations of mercury and low volatile metals were less than
hazardous waste by approximately an order of magnitude at every
facility except one. Thus, a cement kiln feeding a hazardous waste fuel
is likely to emit more metal hazardous air pollutants than a
nonhazardous waste burning cement kiln. Given this difference in
emissions characteristics, we divided the Portland cement manufacturing
source category into two classes based on whether hazardous waste is
burned in the cement kiln.
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\111\ USEPA, ``Final Technical Support Document for HWC MACT
Standards, Volume III: Selection of MACT Standards and
Technologies,'' July 1999.
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Today's rule does not establish hazardous air pollutant emissions
limits for other hazardous air pollutant-emitting sources at a
hazardous waste burning cement plant. These other sources of hazardous
air pollutants may include materials handling operations, conveyor
system transfer points, raw material dryers, and clinker coolers.
Emissions from these sources are subject to the requirements
promulgated in the June 14, 1999 Portland cement manufacturing NESHAP.
See 64 FR 31898. These standards are applicable to these other sources
of hazardous air pollutants at all Portland cement plants, both for
nonhazardous waste burners and hazardous waste burners.
In addition, this regulation does not establish standards for
cement kiln dust management facilities (e.g., cement kiln dust piles or
landfills). We are developing cement kiln dust storage and disposal
requirements in a separate rulemaking.
2. What Is the Basis for Differences in Standards for Hazardous Waste
and Nonhazardous Waste Burning Cement Kilns?
Today's final standards for hazardous waste burning cement kilns
are identical in some respects to those finalized for nonhazardous
waste burning cement kilns on June 14, 1999. The standards differ,
however, in several important aspects. A comparison of the major
features of the two sets of standards and the basis for major
differences is discussed below.
a. How Does the Regulation of Area Sources Differ? As discussed
earlier, this rule makes a positive area source finding under section
112(c)(3) of the CAA (i.e., a finding that hazardous air pollutant
emissions from an area source can pose potential risk to human health
and the environment) for existing hazardous waste burning cement kilns
and subjects area sources to the same standards that apply to major
sources. (See Part Three, Section III.B of today's preamble.) For
nonhazardous waste burning cement kilns, however, we regulate area
sources under authority of
[[Page 52872]]
section 112(c)(6) of the CAA, and so apply MACT standards only to the
section 112(c)(6) hazardous air pollutants emitted from such sources.
The positive finding for hazardous waste burning cement kilns is
based on several factors and, in particular, on concern about potential
health risk from emissions of mercury and nondioxin/furan organic
hazardous air pollutants which are products of incomplete combustion.
However, we do not have this same level of concern with hazardous
air pollutant emissions from nonhazardous waste burning cement kilns
located at area source cement plants, and so did not make a positive
area source finding. As discussed above, mercury emissions from
hazardous waste burning cement kilns are generally higher than those
from nonhazardous waste burning cement kilns. Also, nondioxin and
nonfuran organic hazardous air pollutants emitted from hazardous waste
burning cement kilns have the potential to be greater than those from
nonhazardous waste burning cement kilns because hazardous waste can
contain high concentrations of a wide-variety of organic hazardous air
pollutants. In addition, some hazardous waste burning cement kilns feed
containers of hazardous waste at locations (e.g., midkiln, raw material
end of the kiln) other than the normal coal combustion zone. If such
firing systems are poorly designed, operated, or maintained, emissions
of nondioxin and furan organic hazardous air pollutants could be
substantial (and, again, significantly greater than comparable
emissions from nonhazardous waste Portland cement plants). Finally,
hazardous air pollutant emissions from nonhazardous waste burning
cement kilns currently are not regulated uniformly under another
statute as is the case for hazardous waste burning cement kilns which
affects which pollutants are controlled at the floor for each class.
Under the June 1999 final rule, existing and new nonhazardous waste
burning cement kilns at area source plants are subject to dioxin and
furan emission standards, and a hydrocarbon 112 standard for
new nonhazardous waste burning cement kilns that are area sources.
These standards are promulgated under the authority of section
112(c)(6). That section requires the Agency to establish MACT standards
for source categories contributing significantly in the aggregate to
emissions of identified, particularly hazardous air pollutants. The
MACT process was also applied to the control of mercury, although the
result was a standard of no control.
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\112\ Hydrocarbon emissions would be limited as a surrogate for
polycyclic organic matter, a category of organic hazardous air
pollutants identified in section 112(c)(6).
---------------------------------------------------------------------------
b. How Do the Emission Standards Differ? The dioxin, furan and
particulate matter emission standards for nonhazardous waste burning
cement kilns are identical to today's final standard for hazardous
waste burning cement kilns. The standards for both classes of kilns are
floor standards and are identical because hazardous waste burning is
not likely to affect emissions of either dioxin/furan 113 or
particulate matter. We also conclude that beyond-the-floor standards
for these pollutants would not be cost-effective for either class of
cement kilns.
---------------------------------------------------------------------------
\113\ Later in the text, however, we discuss how hazardous waste
burning may potentially affect dioxin and furan emissions and the
additional requirements for hazardous waste burning cement kilns
that address this concern.
---------------------------------------------------------------------------
Under today's rule, hazardous waste burning cement kilns are
subject to emission standards for mercury, semivolatile metals, low
volatile metals, and hydrochloric acid/chlorine gas, but we did not
finalize such standards for nonhazardous waste burning cement kilns.
Currently, emissions of these hazardous air pollutants from hazardous
waste burning cement kilns are regulated under RCRA. Therefore, we
could establish floor levels for each pollutant under the CAA. These
hazardous air pollutants, however, currently are not controlled for
nonhazardous waste burning cement kilns and floor levels would be
uncontrolled levels (i.e., the highest emissions currently
achieved).114 We considered beyond-the-floor controls and
emission standards for mercury and hydrochloric acid for nonhazardous
waste burning cement kilns, but conclude that beyond-the-floor
standards are not cost-effective, especially considering the lower
rates of current emissions for nonhazardous waste burning plants.
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\114\ Although semivolatile metal and low volatile metal are
controlled by nonhazardous waste burning cement kilns, along with
other metallic hazardous air pollutants, by controlling particulate
matter. These metals are not individually controlled by nonhazardous
waste burning cement kilns as they are for hazardous waste burning
cement kilns by virtue of individual metal feedrate limits
established under existing RCRA regulations.
---------------------------------------------------------------------------
Finally, under today's rule, hazardous waste burning cement kilns
are subject to emission limits on carbon monoxide and hydrocarbon and a
destruction and removal efficiency standard to control nondioxin/furan
organic hazardous air pollutants. We identified these controls as floor
controls because carbon monoxide and hydrocarbon emissions are
controlled for these sources under RCRA regulations, as is destruction
and removal efficiency.115 For nonhazardous waste burning
cement kilns, carbon monoxide and hydrocarbon emissions currently are
not controlled, and the destruction and removal efficiency standard,
established under RCRA, does not apply. Therefore, carbon monoxide,
hydrocarbon control and the destruction and removal efficiency standard
are not floor controls for this second group of cement kilns. We
considered beyond-the-floor controls for hydrocarbon from nonhazardous
waste burning cement kilns and determined that beyond-the-floor
controls for existing sources are not cost-effective. The basis of this
conclusion is discussed in the proposed rule for nonhazardous waste
burning cement kilns (see 63 FR at 14202). We proposed and finalized,
however, a hydrocarbon emission standard for new source nonhazardous
waste cement kilns based on feeding raw materials without an excessive
organic content.116 See 63 FR at 14202 and 64 FR 31898.
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\115\ For hazardous waste burning cement kilns, existing RCRA
carbon monoxide and hydrocarbon standards do not apply to the main
stack of a kiln equipped with a by-pass or other means of measuring
carbon monoxide or hydrocarbon at mid kiln to ensure good combustion
of hazardous waste. Therefore, there is no carbon monoxide or
hydrocarbon floor control for such stacks, and we conclude that
beyond-the-floor controls would not be cost-effective.
\116\ Consistent with the nonhazardous waste burnign cement kiln
proposal, however, we subject the main stack of such new source
hazardous waste burning cemen tkilns to a hydrocarbon standard.
---------------------------------------------------------------------------
We did not consider a destruction and removal efficiency standard
as a beyond-the-floor control for nonhazardous waste burning cement
kilns because, based historically on a unique RCRA statutory provision,
the DRE standard is designed to ensure destruction of organic hazardous
air pollutants in hazardous waste fed to hazardous waste combustors.
The underlying rationale for such a standard is absent for nonhazardous
waste burning cement kilns that do not combust hazardous waste and that
feed materials (e.g., limestone, coal) that contain only incidental
levels of organic hazardous air pollutants.
c. How Do the Compliance Procedures Differ? We finalized compliance
procedures for nonhazardous waste burning cement kilns that are similar
to those finalized today for hazardous waste burning cement kilns. For
particulate matter, we are implementing a coordinated program to
document the feasibility of particulate matter continuous emissions
monitoring
[[Page 52873]]
systems on both nonhazardous waste and hazardous waste burning cement
kilns. We plan to establish a continuous emissions monitoring systems-
based emission level through future rulemaking that is achievable by
sources equipped with MACT control (i.e., an electrostatic precipitator
or fabric filter designed, operated, and maintained to meet the New
Source Performance Standard particulate matter standard). In the
interim, we use the opacity standard as required by the New Source
Performance Standard for Portland cement plants under Sec. 60.62 to
ensure compliance with the particulate matter standard for both
hazardous waste and nonhazardous waste burning cement kilns.
For dioxin/furan, the key compliance parameter will be identical
for both hazardous waste and nonhazardous waste burning cement kilns--
control of temperature at the inlet to the particulate matter control
device. Other factors that could contribute to the formation of dioxins
and furans, however, are not completely understood. As a result,
hazardous waste burning cement kilns have additional compliance
requirements to ensure that hazardous waste is burned under good
combustion conditions. These additional controls are necessary because
of the dioxin and furan precursors that can be formed from improper
combustion of hazardous waste, given the hazardous waste firing systems
used by some hazardous waste burning cement kilns and the potential for
hazardous waste to contain high concentrations of many organic
hazardous air pollutants not found in conventional fuels or cement kiln
raw materials.
We also require both hazardous waste and nonhazardous waste burning
cement kilns to conduct performance testing midway between the five-
year periodic comprehensive performance testing to confirm that dioxin/
furan emissions do not exceed the standard when the source operates
under normal conditions.
C. What Further Subcategorization Considerations Are Made?
We also fully considered further subdividing the class of hazardous
waste burning cement kilns itself. For the reasons discussed below, we
decided that subcategorization is not needed to determine achievable
MACT standards for all hazardous waste burning cement kilns.
We considered, but rejected, subdividing the hazardous waste
burning cement kiln source category on the basis of raw material feed
preparation, more specifically wet process versus dry process. In the
wet process, raw materials are ground, wetted, and fed into the kiln as
a slurry. Approximately 70 percent of the hazardous waste burning
cement kilns in operation use a wet process. In the dry process, raw
materials are ground dry and fed into the kiln dry. Within the dry
process there are three variations: Long kiln dry process, preheater
process, and preheater-precalciner process. We decided not to
subcategorize the hazardous waste burning cement kiln category based on
raw material feed preparation because: (1) The wet process kilns and
all variations of the dry process kilns use similar raw materials,
fossil fuels, and hazardous waste fuels; (2) the types and
concentrations of uncontrolled hazardous air pollutant emissions are
similar for both process types;117 (3) the same types of
particulate matter pollution control equipment, specifically either
fabric filters or electrostatic precipitators, are used by both process
types, and the devices achieve the same level of performance when used
by both process types; and (4) the MACT controls we identify are
applicable to both process types of cement kilns. For example, MACT
floor controls for metals and chlorine include good particulate matter
control and hazardous waste feedrate control, as discussed below, the
particulate matter standard promulgated today is based on the New
Source Performance Standard, which applies to all cement kilns
irrespective of process type. Further, a cement kiln operator has great
discretion in the types of hazardous waste they accept including the
content of metals and chlorine in the waste. These basic control
techniques--particulate matter control and feedrate control of metals
and chlorine--clearly show that subcategorization based on process type
is not appropriate.
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\117\ Although dry process kilns with a separate by-pass stack
can have higher metals emissions from that stack compared to the
main stack of other kilns, today's rule allows such kilns to
flowrate-average its emissions between the main and by-pass stack.
The average emissions are similar to the emissions from dry and wet
kilns that have only one stack. Similarly, kilns with in-line raw
mills have higher mercury emissions when the raw mill is off.
Today's rule allows such kilns to time-weight average their
emissions, however, and the time-weighted emissions for those kilns
are similar to emissions from other hazardous waste burning cement
kilns.
---------------------------------------------------------------------------
Some commenters stated that it is not feasible for wet process
cement kilns to use fabric filters, especially in cold climates, and
thus subcategorization based on process type is appropriate. The
problem, commenters contend, is that the high moisture content of the
flue gas will clog the fabric if the cement-like particulate is wetted
and subsequently dried, resulting in reduced performance and early
replacement of the fabric filter bags. Other commenters disagreed with
these assertions and stated that fabric filter technology can be
readily applied to wet process kilns given the exit temperatures of the
combustion gases and the ease of insulating fabric filter systems to
minimize cold spots in the baghouse to avoid dew point problems and
minimize corrosion. These commenters pointed to numerous wet process
applications currently in use at cement kilns with fabric filter
systems located in cold climates to support their claims.118
In light of the number of wet process kilns already using fabric
filters and their various locations, we conclude that wet process
cement kilns can be equipped with fabric filter systems and that
subdividing by process type on this basis is not necessary or
warranted. A review of the particulate matter emissions data for one
wet hazardous waste burning cement kiln using a fabric filter shows
that it is achieving the particulate matter standard. We do not have
data in our data base from the only other wet hazardous waste burning
cement kiln using a fabric filter; however, this cement kiln recently
installed and upgraded to a new fabric filter system.
---------------------------------------------------------------------------
\118\ We are aware of four wet process cement kiln facilities
operating with fabric filters: Dragon (Thomaston, ME), Giant
(Harleyville, SC), Holnam (Dundee, MI), and LaFarge (Paulding, OH).
Commenters also identified kilns in Canada operating with fabric
filters.
---------------------------------------------------------------------------
We also fully considered, but ultimately rejected, subdividing the
hazardous waste burning cement kiln source category between long kilns
and short kilns (preheater and preheater-precalciner) technologies, and
those with in-line kiln raw mills. This subcategorization approach was
recommended by many individual cement manufacturing member companies
and a cement manufacturing trade organization. Based on information on
the types of cement kilns that are currently burning hazardous waste,
these three subcategories consist of the following four subdivisions:
(1) Short kilns with separate by-pass and main stacks; (2) short kilns
with a single stack that handles both by-pass and preheater or
precalciner emissions; (3) long dry kilns that use kiln gas to dry raw
meal in the raw mill; and (4) others wet kilns, and long dry kilns not
using in-line kiln raw mill drying. Currently, each of the first three
categories consists of only one cement kiln facility while
[[Page 52874]]
the kilns at the remaining 15 facilities are in the fourth category:
wet kilns or long dry kilns that do not use in-line kiln raw mill
drying.
Commenters state that these subcategories should be considered
because the unique design or operating features of the different types
of kilns could have a significant impact on emissions of one or more
hazardous air pollutants that we proposed to regulate. Specifically,
commenters noted the potential flue gas characteristic differences for
cement kilns using alkali bypasses on short kilns and in-line kiln raw
mills. For example, kilns with alkali bypasses are designed to divert a
portion of the flue gas, approximately 10-30%, to remove the
problematic alkalis, such as potassium and sodium oxides, that can
react with other compounds in the cool end of the kiln resulting in
operation problems. Thus, bypasses allow evacuation of the undesirable
alkali metals and salts, including semivolatile metals and chlorides,
entrained in the kiln exit gases before they reach the preheater
cyclones. As a result, the commenters stated that the emission
concentration of semivolatile metals in the bypass stack is greater
than in the main stack, and therefore the difference in emissions
supports subcategorization.
We agree, in theory, that the emissions profile for some hazardous
air pollutants can be different for the three kilns types--short kilns
with and without separate bypass stacks, long kilns with in-line kiln
raw mills. To consider this issue further, we analyzed floor control
and floor emissions levels based only on the data and information from
the other long wet kilns and long dry kilns not using raw mill drying.
We then considered whether the remaining three kiln types could apply
the same MACT controls and achieve the resulting emission standards. We
conclude that these three types of kilns at issue can use the MACT
controls and achieve the corresponding emission levels identified in
today's rule for the wet kilns and long dry kilns not using raw mill
drying.119 As a result, we conclude that there is no
practical necessity driving a subcategorization approach even though
one would be theoretically possible. Further, to ensure that today's
standards are achievable by all cement kilns, we establish a provision
that allows cement kilns operating in-line kiln raw mills to average
their emissions based on a time-weighted average concentration that
considers the length of time the in-line raw mill is on-line and off
line. We also adopt a provision that allows short cement kilns with
dual stacks to average emissions on a flow-weighted basis to
demonstrate compliance with the emissions standards. (See Part Five,
Section X--Special Provisions for a discussion of these provisions.)
---------------------------------------------------------------------------
\119\ USEPA, ``Final Technical Support Document for HWC MACT
Standards, Volume III: Selection of MACT Standards and
Technologies,'' July 1999.
---------------------------------------------------------------------------
In the case of hydrocarbons and carbon monoxide, we developed final
standards that reflect the concerns raised by several commenters. We
determined that this approach best accommodated the unique design and
operating differences between long wet and long dry process and short
kilns using either a preheater or a preheater and precalciner.
Existing hazardous waste preheater and preheater-precalciner cement
kilns, one of each type is burning hazardous waste, are equipped with
bypass ducts that divert a portion of the kiln off-gas through a
separate particulate matter control device to remove problematic alkali
metals. Long cement kilns do not use bypasses designed to remove alkali
metals. The significance of this operational difference is that
hydrocarbon and carbon monoxide levels in the bypass gas of short kilns
is more representative of the combustion efficiency of burning
hazardous waste and other fuels in the kiln than the measurements made
in the main stack. Main stack gas measurements of hydrocarbons and
carbon monoxide, regardless of process type, also include contributions
from trace levels of organic matter volatilized from the raw materials,
which can mask the level of combustion efficiency achieved in the kiln.
Today's tailored standards require cement kilns to monitor
hydrocarbons and carbon monoxide at the location best indicative of
good combustion. For short kilns with bypasses, the final rule requires
monitoring of hydrocarbons and carbon monoxide in the bypass. Long
kilns are required to comply with the hydrocarbon and carbon monoxide
standards in the main stack. However, long kilns that operate a mid-
kiln sampling system, for the purpose of removing a representative
portion of the kiln off-gas to measure combustion efficiency, can
comply with the hydrocarbon and carbon monoxide standards at the
midkiln sampling point.
In addition, establishing separate hydrocarbon and carbon monoxide
standards reflects the long and short kiln subcategorization approach
recommended by some commenters. The standards differ because MACT floor
control for hydrocarbons and carbon monoxide is based primarily on the
existing requirements of the Boiler and Industrial Furnace rule. In
that rule, the unique design and operating features of long and short
kilns were considered in establishing type specific emission limits for
hydrocarbons and carbon monoxide. Thus, MACT floor control for long and
short kilns is different. However, we note these same unique design and
operating features were not a factor in establishing standards for
other pollutants, including mercury, semivolatile and low volatile
metals, and hydrochloric acid/chlorine gas, in the Boiler and
Industrial Furnace rule.
For the reasons discussed above, subcategorization would not appear
to be needed to establish uniform, achievable MACT standards for all
cement kilns burning hazardous waste. Thus, because the differences
among kiln types ``does not affect the feasibility and effectiveness of
air pollution control technology,'' subcategorization is not
appropriate. S. Rep. No. 228, 101st Cong. 1st sess. 166.
D. What Are The Standards for Existing and New Cement Kilns?
1. What Are the Standards for Cement Kilns?
In this section, the basis for the emissions standards for cement
kilns is discussed. The kiln emission limits apply to the kiln stack
gases, in-line kiln raw mill stack gases if combustion gases pass
through the in-line raw mill, and kiln alkali bypass stack gases if
discharged through a separate stack from cement plants that burn
hazardous waste in the kiln. The emissions standards are summarized
below:
[[Page 52875]]
Standards for Existing and New Cement Kilns
------------------------------------------------------------------------
Hazardous air pollutant or Emissions standard 1
hazardous air pollutant -------------------------------------------
surrogate Existing sources New sources
------------------------------------------------------------------------
Dioxin and furan............ 0.20 ng TEQ/dscm; or 0.20 ng TEQ/dscm; or
0.40 ng TEQ/dscm 0.40 ng TEQ/dscm
and control of flue and control of flue
gas temperature not gas temperature not
to exceed 400 deg.F to exceed 400 deg.F
at the inlet to the at the inlet to the
particulate matter particulate matter
control device. control device.
Mercury..................... 120 g/dscm. 56 g/dscm.
Particulate matter 2........ 0.15 kg/Mg dry feed 0.15 kg/Mg dry feed
and 20% opacity. and 20% opacity.
Semivolatile metals......... 240 g/dscm. 180 g/dscm.
Low volatile metals......... 56 g/dscm.. 54 g/dscm.
Hydrochloric acid and 130 ppmv............ 86 ppmv.
chlorine gas.
Hydrocarbons: kilns without 20 ppmv (or 100 ppmv Greenfield kilns: 20
by-pass 3, 6. carbon monoxide) 3. ppmv (or 100 ppmv
carbon monoxide and
50 ppmv 5
hydrocarbons).
.................... All others: 20 ppmv
(or 100 ppmv carbon
monoxide) 3.
Hydrocarbons: kilns with by- No main stack 50 ppmv 5.
pass; main stack 4, 6. standard.
Hydrocarbons: kilns with by- 10 ppmv (or 100 ppmv 10 ppmv (or 100 ppmv
pass; by-pass duct and carbon monoxide). carbon monoxide).
stack 3, 4, 6.
Destruction and removal For existing and new sources, 99.99% for
efficiency. each principal organic hazardous
constituent (POHC) designated. For
sources burning hazardous wastes F020,
F021, F022, F023, F026, or F027, 99.9999%
for each POHC designated.
------------------------------------------------------------------------
\1\ All emission levels are corrected to 7% O2, dry basis.
\2\ If there is an alkali by-pass stack associated with the kiln or in-
line kiln raw mill, the combined particulate matter emissions from the
kiln or in-line kiln raw mill and the alkali by-pass must be less than
the particulate matter emissions standard.
\3\ Cement kilns that elect to comply with the carbon monoxide standard
must demonstrate compliance with the hydrocarbon standard during the
comprehensive performance test.
\4\ Measurement made in the by-pass sampling system of any kiln (e.g.,
alkali by-pass of a preheater and/or precalciner kiln; midkiln
sampling system of a long kiln).
\5\ Applicable only to newly-constructed cement kilns at greenfield
sites (see discussion in Part Four, Section VII.D.9). 50 ppmv standard
is a 30-day block average limit. Hydrocarbons reported as propane.
\6\ Hourly rolling average. Hydrocarbons are reported as propane.
2. What Are the Dioxin and Furan Standards?
In today's rule, we establish a standard for new and existing
cement kilns that limits dioxin/furan emissions to either 0.20 ng TEQ/
dscm; or 0.40 ng TEQ/dscm and temperature at the inlet to the
particulate matter control device not to exceed
400 deg.F.120 Our rationale for these standards is discussed
below.
---------------------------------------------------------------------------
\120\ The temperature limit applies at the inlet to a dry
particulate matter control device that suspends particulate matter
in the combustion gas stream (e.g., electrostatic precipitator,
fabric filter) such that surface-catalyzed formation of dioxin/furan
is enhanced. The temperature limit does not apply to a cyclone
control device, for example.
---------------------------------------------------------------------------
a. What Is the MACT Floor for Existing Sources? In the April 1996
proposal, we identified floor control as either temperature control at
the inlet to the particulate matter control device of less than
418 deg.F, or achieving a specific level of dioxin/furan emissions
based upon levels achievable using proper temperature control. (61 FR
at 17391.) The proposed floor emission level was 0.20 ng TEQ/dscm, or
temperature at the inlet to the electrostatic precipitator or fabric
filter not to exceed 418 deg.F. In the May 1997 NODA, we identified an
alternative data analysis method to identify floor control and the
floor emission level. Floor control for dioxin/furan was defined as
temperature control at the inlet to the electrostatic precipitator or
fabric filter at 400 deg.F, which was based on further engineering
evaluation of the emissions data and other available information. That
analysis resulted in a floor emission level of 0.20 ng TEQ/dscm, or
0.40 ng TEQ/dscm and temperature at the inlet to the electrostatic
precipitator or fabric filter not to exceed 400 deg.F. (62 FR at
24226.) The 0.40 ng TEQ/dscm standard is the level that all cement
kilns, including data from nonhazardous waste burning cement kilns, are
achieving when operating at the MACT floor control level or better. We
considered a data set that included dioxin/furan emissions from
nonhazardous waste burning cement kilns because these data are
adequately representative of general dioxin/furan behavior and control
in either type of kiln. The impacts of hazardous waste constituents
(HAPs) on the emissions of those HAPs prevent us from expanding our
database for other HAPs in a similar way.
We conclude that the floor methodology discussed in the May 1997
NODA is appropriate and we adopt this approach in today's final rule.
We identified two technologies for control of dioxin/furan emissions
from cement kilns in the May 1997 NODA. The first technology achieves
low dioxin/furan emissions by quenching kiln gas temperatures at the
exit of the kiln so that gas temperatures at the inlet to the
particulate matter control device are below the temperature range of
optimum dioxin/furan formation. For example, we are aware of several
cement kilns that have recently added flue gas quenching units upstream
of the particulate matter control device to reduce the inlet
particulate matter control device temperature resulting in
significantly reduced dioxin/furan levels.121 The other
technology is activated carbon injected into the kiln exhaust gas.
Since activated carbon injection is not currently used by any hazardous
waste burning cement kilns, this technology was evaluated only as part
of a beyond-the-floor analysis.
---------------------------------------------------------------------------
\121\ USEPA, ``Final Technical Support Document for HWC MACT
Standards. Volume III: Selection of Proposed MACT Standards and
Technologies'', July 1999. See Section 3.2.1.
---------------------------------------------------------------------------
As discussed in the May 1997 NODA, specifying a temperature
limitation of 400 deg.F or lower is appropriate for floor control
because, from an engineering perspective, it is within the range of
[[Page 52876]]
reasonable values that could have been selected considering that: (1)
The optimum temperature window for surface-catalyzed dioxin/furan
formation is approximately 450-750 deg.F; and (2) temperature levels
below 350 deg.F can cause dew point condensation problems resulting in
particulate matter control device corrosion, filter cake cementing
problems, increased dust handling problems, and reduced performance of
the control device. (62 FR at 24226.)
Several commenters disagreed with our selection of 400 deg.F as the
particulate matter control device temperature limitation and stated
that other higher temperature limitations were equally appropriate as
MACT floor control. Based on these NODA comments, we considered
selecting a temperature limitation of 450 deg.F, generally regarded to
be the lower end of the temperature range of optimum dioxin/furan
formation. However, available data indicate that dioxin/furan formation
can be accelerated at kilns operating their particulate matter control
device at temperatures between 400-450 deg.F. Data from several kilns
show dioxin/furan emissions as high as 1.76 ng TEQ/dscm when operating
in the range of 400-450 deg.F. Identifying a higher temperature limit
such as 450 deg.F is not consistent with other sources achieving much
lower emissions at 400 deg.F, and thus identifying a higher temperature
limit would not be MACT floor control.
Some commenters also state that EPA has failed to demonstrate that
the best performing 12 percent of existing sources currently use
temperature control to reduce dioxin/furan emissions, and therefore,
temperature control is more appropriately considered in subsequent
beyond-the-floor analyses. However, particulate matter control device
operating temperatures associated with the emissions data used to
establish the dioxin/furan standard are based on the maximum operating
limits set during compliance certification testing required by the
Boiler and Industrial Furnace rule. See 40 CFR 266.103(c)(1)(viii). As
such, cement kilns currently must comply with these temperature limits
on a continuous basis during day-to-day operations, and therefore,
these temperature limits are properly assessed during an analysis of
MACT floors.
Several commenters also oppose consideration of dioxin/furan
emissions data from nonhazardous waste burning cement kilns in
establishing the floor standard. Commenters state that pooling the
available emissions data from hazardous waste burning cement kiln with
data from nonhazardous waste burning cement kilns to determine the MACT
floor violates the separate category approach that EPA decided upon for
the two classes of cement kilns. Notwithstanding our decision to divide
the Portland cement manufacturing source category based on the kiln's
hazardous waste burning status, we considered both hazardous waste
burning cement kiln and nonhazardous waste burning cement kiln data
together because both data sets are adequately representative of
general dioxin/furan behavior and control in either type of kiln. This
similarity is based on our engineering judgement that hazardous waste
burning does not have an impact on dioxin/furan formation, dioxin/furan
is formed post-combustion. Though the highest dioxin/furan emissions
data point from MACT (i.e., operating control device less than
400 deg.F) hazardous waste and nonhazardous waste burning cement kiln
sources varies somewhat (0.28 vs 0.37 ng TEQ/dscm respectively), it is
our judgment that additional emissions data, irrespective of hazardous
waste burning status, would continue to point to a floor of within the
range of 0.28 to 0.37 ng TEQ/dscm. This approach ensures that the floor
levels for hazardous waste burning cement kilns are based on the
maximum amount of relevant data, thereby ensuring that our judgment on
what floor level is achievable is as comprehensive as possible.
We estimate that approximately 70 percent of test condition data
from hazardous waste burning cement kilns are currently emitting less
than 0.40 ng TEQ/dscm (irrespective of the inlet temperature to the
particulate matter control device). In addition, approximately 50
percent of all test condition data are less than 0.20 ng TEQ/dscm. The
national annualized compliance cost for cement kilns to reduce dioxin/
furan emissions to comply with the floor standard is $4.8 million for
the entire hazardous waste burning cement industry and will reduce
dioxin/furan emissions by 5.4 g TEQ/yr or 40 percent from current
baseline emissions.
b. What Are Our Beyond-the-Floor Considerations for Existing
Sources? We considered in the April 1996 proposal and May 1997 NODA a
beyond-the-floor standard of 0.20 ng TEQ/dscm based on activated carbon
injection at a temperature of less than 400 deg.F. We continue to
believe that a beyond-the-floor standard 0.20 ng TEQ/dscm based on
activated carbon injection is the appropriate beyond-the-floor standard
to evaluate given the risks posed by dioxin/furan emissions.
Carbon injection is routinely effective at removing 99 percent of
dioxin/furans for numerous municipal waste combustor and mixed waste
incinerator applications and one hazardous waste incinerator
application. However, currently no hazardous waste burning cement kilns
use activated carbon injection for dioxin/furan removal. For cement
kilns, we believe that it is conservative to assume only 95 percent is
achievable given that the floor level is already low at 0.40 ng/dscm.
As dioxin/furans decrease, activated carbon injection efficiency is
expected to decrease. In addition, we assumed for cost-effectiveness
calculations that cement kilns needing activated carbon injection to
achieve the beyond-the-floor standard would install the activated
carbon injection system after the normal particulate matter control
device and add a new, smaller fabric filter to remove the injected
carbon with the absorbed dioxin/furan and mercury.122 The
costing approach addresses commenter's concerns that injected carbon
may interfere with cement kiln dust recycling practices.
---------------------------------------------------------------------------
\122\ We received many comments on the use of activated carbon
injection as a beyond-the-floor control techniques at cement kilns.
Since we do not adopt a beyond-the-floor standard based on activated
carbon injection in the final rule, these comments and our responses
to them are only discussed in our document that responds to public
comments.
---------------------------------------------------------------------------
The national incremental annualized compliance cost for the
remaining cement kilns to meet this beyond-the-floor level, rather than
comply with the floor controls, would be approximately $2.5 million for
the entire hazardous waste burning cement industry and would provide an
incremental reduction in dioxin/furan emissions nationally beyond the
MACT floor controls of 3.7 g TEQ/yr. Based on these costs,
approximately $0.66 million per g dioxin/furan removed, we determined
that this dioxin/furan beyond-the-floor option for cement kilns is not
justified. Therefore, we are not adopting a beyond-the-floor standard
of 0.2 ng TEQ/dscm.
We note that one possible explanation of high cost-effectiveness of
the beyond-the-floor standard may be due to the significant reduction
in national dioxin/furan emissions achieved over the past several years
by hazardous waste burning cement kilns due to emissions improving
modifications. The hazardous waste burning cement kiln national dioxin/
furan emissions estimate for 1997 decreased by nearly
[[Page 52877]]
97% since 1990, from 431 g TEQ/yr to 13.1 g TEQ/yr.123
---------------------------------------------------------------------------
\123\ USEPA, ``Final Technical Support Document for HWC MACT
Standards, Volume V: Emission Estimates and Engineering Costs'',
July 1999. See also 63 FR 17338, April 10, 1998.
---------------------------------------------------------------------------
c. What Is the MACT Floor for New Sources? At proposal, we
identified floor control for new sources as temperature control at the
inlet to the particulate matter control device at 409 deg.F. The
proposed floor emission level was 0.20 ng TEQ/dscm, or temperature at
the inlet to the particulate matter control device not to exceed
409 deg.F. In the May 1997 NODA, we identified an alternative data
analysis method to identify floor control and the floor emission level.
The May 1997 NODA dioxin/furan floor control for new sources was
defined as temperature control at the inlet to the electrostatic
precipitator or fabric filter at 400 deg.F, which was based on an
engineering evaluation of the emissions data and other available
information. That analysis resulted in a floor emission level of 0.20
ng TEQ/dscm, or 0.40 ng TEQ/dscm and temperature at the inlet to the
electrostatic precipitator or fabric filter not to exceed 400 deg.F. We
continue to believe that the floor methodology is appropriate for new
sources and we adopt this approach in this final rule.
d. What Are Our Beyond-the-Floor Considerations for New Sources? In
both the April 1996 proposal and May 1997 NODA, we proposed activated
carbon injection as beyond-the-floor control and a beyond-the-floor
standard of 0.20 ng TEQ/dscm for new sources. For reasons discussed
above for existing sources, we conclude that it is also not cost-
effective for new cement kilns to achieve this level. Thus, we do not
adopt a beyond-the-floor dioxin/furan standard for new cement kilns.
3. What Are the Mercury Standards?
In today's rule, we establish a standard for existing and new
cement kilns that limits mercury emissions to 120 and 56 g/
dscm, respectively. The rationale for these standards is discussed
below.
a. What Is the MACT Floor for Existing Sources? All cement kilns
use either electrostatic precipitators or fabric filters for
particulate matter control. However, since mercury is generally in the
vapor form in and downstream of the combustion chamber, including the
air pollution control device, electrostatic precipitators and fabric
filters do not achieve good mercury control. Mercury emissions from
cement kilns are currently regulated by the Boiler and Industrial
Furnace rule, which establishes limits on the maximum feedrate of
mercury in total feedstreams (e.g., hazardous waste, raw materials,
coal). Thus, MACT floor control is based on hazardous waste feed
control.
In the April 1996 proposal, we identified floor control as
hazardous waste feedrate control not to exceed a feedrate level of 110
g/dscm, expressed as a maximum theoretical emission
concentration, and proposed a floor standard of 130 g/dscm
based on an analysis of data from all cement kilns with a hazardous
waste mercury feedrate of this level or lower. (61 FR at 17393.) In May
1997 NODA, we conducted a breakpoint analysis on low to high ranked
mercury emissions data from sources floor control and established the
floor level as the test condition average emission of the breakpoint
source. The breakpoint analysis was intended to reflect an engineering-
based evaluation of the data so that the few cement kilns spiking
mercury during compliance testing did not drive the floor standard to
levels higher than the preponderance of the emissions data. We reasoned
that sources with emissions higher than the breakpoint source were not
controlling the hazardous waste feedrate of mercury to levels
representative of MACT. This analysis resulted in a MACT floor level of
72 g/dscm. (62 FR at 24227.)
For today's rule, in response to comments questioning our May 1997
NODA approach, we use a revised engineering evaluation and data
analysis method to establish the MACT floor for mercury. As discussed
in greater detail in the methodology section previously, we use an
aggregate feedrate approach to establish MACT floors for the three
metal hazardous air pollutant groups and hydrochloric acid/chlorine
gas. The aggregate feedrate approach first identifies a MACT floor
feedrate level for mercury and then establishes the floor emission
level as the highest emissions level achieved by any cement kilns using
floor control or better. Using this approach, the resulting mercury
floor emission level is 120 g/dscm.
We received comments on several overarching issues including the
appropriateness of considering feedrate control of mercury in hazardous
waste as a MACT floor control technique and the specific procedure of
identifying breakpoints in arrayed emissions data. These issues and our
response to them are discussed in the floor methodology section in Part
Four, Section V. In addition, we received comment on a special
provision that would allow cement kilns (and lightweight aggregate
kilns) to petition the Administrator for an alternative mercury
standard for kilns with mercury concentrations in their mineral and
related process raw materials that causes an exceedance of the emission
standard. This issue and the alternative standard promulgated in the
final rule is fully discussed in Part Five, Section X.A.
We also received comments from the cement manufacturing industry
indicating that cement kilns with in-line raw mills have unique design
and operating procedures that necessitate the use of emission averaging
when demonstrating compliance with the emission standards. These
commenters stated that the mercury standard is not achievable without a
procedure for kilns to emissions average. The commenters supported a
provision allowing cement kilns with in-line raw mills to demonstrate
compliance with the emission standards on a time-weighted average basis
to account for different emission characteristics when the raw mill is
active as opposed to when it is inactive. After fully considering
comments received, we adopt an emission averaging provision in the
final rule. This provision is fully discussed in Part Five, Section
X.E.
Several commenters expressed concern that the mercury emissions
data base for cement kilns is comprised of normal data, that is, cement
kilns did not spike mercury during RCRA compliance testing as they did
for other metals and chlorine. Thus, commenters stated that an
emissions variability factor should be added to a floor level derived
directly from the emissions data to ensure that the floor emission
level is being achieved in practice. As discussed in Section V.D.1
above, we conclude that emissions variability is adequately accounted
for by the MACT floor methodology finalized today.
We estimate that 85 percent of cement kilns currently meet the
floor level. The national annualized compliance cost for cement kilns
to reduce mercury emissions to comply with the floor level is $1.1
million for the entire hazardous waste burning cement industry and will
reduce mercury emissions by 0.2 Mg/yr or 15 percent from current
baseline emissions.
b. What Are Our Beyond-the-Floor Considerations for Existing
Sources? In the April 1996 NPRM, we proposed a beyond-the-floor
standard of 50 g/dscm based on flue gas temperature reduction
to 400 deg.F followed by activated carbon injection for mercury
capture. (61 FR at 17394.) In the May 1997 NODA, we considered a
beyond-the-floor standard of 30 g/dscm based on activated
carbon
[[Page 52878]]
injection; however, an evaluation was not conducted to determine if
such a level would be cost-effective. (62 FR at 24227.)
In developing the final rule, we identified three techniques for
control of mercury as a basis to evaluate a beyond-the-floor standard:
(1) Activated carbon injection; (2) limiting the feed of mercury in the
hazardous waste; and (3) limiting the feed of mercury in the raw
materials. The results of each analysis are discussed below.
i. Activated Carbon Injection. To investigate activated carbon
injection, we applied a carbon injection capture efficiency of 80
percent to the floor emission level of 120 g/dscm. Our basis
for selecting a capture efficiency of 80 percent 124 is
discussed in the support document.125 The resulting beyond-
the-floor emission level is 25 g/dscm.
---------------------------------------------------------------------------
\124\ We received many comments on the use of activated carbon
injection as a beyond-the-floor control technique at cement kilns.
Since we do not adopt a beyond-the-floor standard based on activated
carbon injection in the final rule, these comments and our responses
to them are only discussed in our document that responds to public
comments.
\125\ USEPA, ``Final Technical Support Document for HWC MACT
Standards, Volume III: Selection of MACT Standards and
Technologies.'' July 1999.
---------------------------------------------------------------------------
We then determined the cost of achieving this reduction to
determine if a beyond-the-floor standard of 25 g/dscm would be
appropriate. The national incremental annualized compliance cost for
the remaining cement kilns to meet this beyond-the-floor level, rather
than comply with the floor controls, would be approximately $11.1
million for the entire hazardous waste burning cement kiln industry and
would provide an incremental reduction in mercury emissions nationally
beyond the MACT floor controls of 0.7 Mg/yr. Based on these costs of
approximately $16 million per additional Mg of mercury removed, we
conclude that this mercury beyond-the-floor option for cement kilns is
not acceptably cost-effective nor otherwise justified. Therefore, we do
not adopt this beyond-the-floor standard.
ii. Limiting the Feedrate of Mercury in the Hazardous Waste. We
also considered a beyond-the-floor standard of 50 g/dscm based
on limiting the feedrate of mercury in the hazardous waste. An emission
level of 50 g/dscm represents the practicable extent that
additional feedrate control of mercury in hazardous waste (beyond
feedrate control needed to achieve the floor emission level) can be
used and still achieve modest emissions reductions. We investigated the
cost of achieving this reduction to determine if this beyond-the-floor
standard would be appropriate. The national incremental annualized
compliance cost for cement kilns to meet a beyond-the-floor level of 50
g/dscm, rather than comply with the floor controls, would be
approximately $4.2 million for the entire hazardous waste burning
cement kiln industry and would provide an incremental reduction in
mercury emissions nationally beyond the MACT floor controls of 0.4 Mg/
yr. Based on these costs of approximately $10.9 million per additional
Mg of mercury removed, we conclude that this mercury beyond-the-floor
option for cement kilns is not warranted. Therefore, we did not adopt
this mercury beyond-the-floor standard.
iii. Limiting the Feedrate of Mercury in Raw Materials. Finally, we
considered a beyond-the-floor standard based on limiting the feedrate
of mercury in the raw materials. Cement manufacturing involves the
heating of raw materials such as limestone, clay, shale, sand, and iron
ore. Limestone, shale, and clay comprise the vast majority of raw
material feed to the kiln, and these materials are typically mined at
quarries nearby the cement kiln. Since feed materials can contain
significant quantities of hazardous air pollutants, we considered
establishing a beyond-the-floor standard based on limiting the feedrate
of mercury in these raw materials. A source can achieve a reduction in
mercury emissions by substituting a feed material containing lower
levels of mercury for a primary raw material with higher mercury
levels. For example, shale is the primary feed material used as a
source of silica. Under this beyond-the-floor option, a source using a
high mercury-containing shale could substitute a feed material lower in
mercury such as a coal ash to achieve lower mercury emissions. This
beyond-the-floor option appears to be less cost-effective compared to
either of the options evaluated above, however. This conclusion is
based on the fact that cement kilns are sited proximate to primary raw
material supply and transporting large quantities of an alternative
source of raw material(s) is likely to be cost-prohibitive, thereby
making a beyond-the-floor standard not cost-effective. Therefore, we do
not adopt this mercury beyond-the-floor standard.
Thus, the promulgated mercury standard for existing hazardous waste
burning cement kilns is the floor level of 120 g/dscm.
c. What Is the MACT Floor for New Sources? In the April 1996
proposal, we identified floor control for new sources as hazardous
waste mercury feedrate control not to exceed a feedrate level of 28
g/dscm expressed as a maximum theoretical emission
concentration. We proposed a floor level of 82 g/dscm. We
discussed a floor emission level for new cement kilns in the May 1997
NODA of 72 g/dscm, based on a floor feedrate control level of
110 g/dscm.
Today we identify floor control for new cement kilns as feedrate
control of mercury in the hazardous waste, expressed as a maximum
theoretical emission concentration, based on the single source with the
best aggregate feedrate of mercury in hazardous waste. Using the
aggregate feedrate approach to establish this floor level of control
and the corresponding floor emission level, we identify a MACT floor
emission level of 56 g/dscm for new hazardous waste burning
cement kilns.126
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\126\ Given that the emission level is substantially higher than
the feedrate level expressed as a maximum theoretical emission
concentration, 56 vs 7 g/dscm, the contributions of mercury
from raw materials and coal for the floor-setting source must be
substantial.
---------------------------------------------------------------------------
d. What Are Our Beyond-the-Floor Considerations for New Sources? At
proposal, we based beyond-the-floor control for new cement kilns on
activated carbon injection and proposed a standard of 50 g/
dscm. In the May 1997 NODA we considered a beyond-the-floor standard of
30 g/dscm based on activated carbon injection as done for
existing sources.
We identified two techniques for control of mercury as a basis to
evaluate a beyond-the-floor standard for new sources: (1) Activated
carbon injection; and (2) limiting the feedrate of mercury in the
hazardous waste. The results of each analysis are discussed below.
i. Activated Carbon Injection. As discussed above, we conclude that
flue gas temperature reduction to 400 deg.F followed by activated
carbon injection to remove mercury is an appropriate beyond-the-floor
control option for improved mercury control at cement kilns. Based on
the MACT floor emission level of 56 g/dscm and assuming a
carbon injection capture efficiency of 80 percent, we identified a
beyond-the-floor emission level of 10 g/dscm. We then
determined the cost of achieving this reduction to determine if a
beyond-the-floor standard of 10 g/dscm would be appropriate.
The incremental annualized compliance cost for one new large cement
kiln to meet this beyond-the-floor level, rather than comply with floor
controls, would be approximately $2.3 million and would provide an
incremental reduction in mercury emissions beyond the MACT floor
controls of approximately 0.17 Mg/yr. For a new small cement kiln, the
[[Page 52879]]
incremental annualized compliance cost would be approximately $0.9
million and would provide an incremental reduction in mercury emissions
beyond the MACT floor controls of approximately 0.04 Mg/yr. Based on
these costs of approximately $13-22 million per additional Mg of
mercury removed, we concluded that a beyond-the-floor standard of 10
g/dscm is not justified due to the high cost of compliance and
relatively small mercury emissions reductions.
ii. Limiting the Feedrate of Mercury in Hazardous Waste. We also
considered a beyond-the-floor standard based on limiting the feedrate
of mercury in the hazardous waste. Considering that the floor emission
level for new cement kilns is approximately half of the floor emission
level for existing kilns (56 versus 120 g/dscm), we conclude
that a mercury beyond-the-floor standard for cement kilns is not
warranted. This conclusion is based on the limited incremental
emissions reductions achieved 127 and because the cost-
effectiveness of beyond-the-floor controls for new cement kilns would
be even higher than for existing sources, which we found unacceptable
in paragraph (b) above. Therefore, we do not adopt a mercury beyond-
the-floor standard based on limiting feedrate of mercury in hazardous
waste.
---------------------------------------------------------------------------
\127\ Achieving substantial additional mercury emissions
reductions by further controls on hazardous waste feedrate may be
problematic because the mercury contribution from raw materials and
coal represents an even larger proportion of the total mercury fed
to the kiln.
---------------------------------------------------------------------------
Thus, the promulgated mercury standard for new hazardous waste
burning cement kilns is the floor emissions level of 56 g/
dscm.
4. What Are the Particulate Matter Standards?
We establish standards for both existing and new cement kilns which
limit particulate matter emissions to 0.15 kg/Mg dry
feed.128 In addition, opacity cannot exceed 20 percent. We
chose the particulate matter standard as a surrogate control for the
metals antimony, cobalt, manganese, nickel, and selenium. We refer to
these five metals as ``nonenumerated metals'' because standards
specific to each metal have not been established. The rationale for
adopting these standards is discussed below.
---------------------------------------------------------------------------
\128\ Approximately equivalent to a particulate matter
concentration of 0.03 gr/dscf (69 mg/dscm) as expressed in the April
1996 NPRM and May 1997 NODA. The calculation is approximate due to
the different types of cement kilns and their associated flow rates.
---------------------------------------------------------------------------
a. What Is the MACT Floor for Existing Sources? In the April 1996
proposal, we discussed particulate matter floor control based upon the
performance of a fabric filter with an air-to-cloth ratio of 2.3 acfm/
f, 2 resulting in a nominal floor emission level of 0.065
gr/dscf. However, we believed it more appropriate to establish the
floor standard based on the cement kiln 1971 New Source Performance
Standard. (See discussion in 61 FR at 17392.) The 1971 New Source
Performance Standard is 0.15 kg/Mg dry feed (0.30 lb/ton of dry feed).
(see 40 CFR 60.60.) Cement kilns currently achieve this standard with
well-designed and properly operated electrostatic precipitators and
fabric filters.
In the May 1997 NODA, we considered two data analysis methods to
identify the particulate matter floor emission level. The first method
established and expressed the floor level equivalent to the existing
New Source Performance Standard promulgated in 1971. We subsequently
proposed and finalized this approach for nonhazardous waste burning
cement kilns. See 63 FR at 14198-199 and 64 FR 31898, respectively. The
second approach discussed expressed the New Source Performance Standard
as a stack gas concentration limit, as opposed to a production-based
emission limit format. The May 1997 reevaluation suggested that the
1971 New Source Performance Standard was approximately equivalent to a
particulate matter concentration of 0.03 gr/dscf (69 mg/
dscm).129 We indicated a preference for expressing the
particulate matter standard on a concentration basis because we also
proposed that sources would comply with the particulate matter standard
with a particulate matter continuous emissions monitoring system.
---------------------------------------------------------------------------
\129\ See USEPA, ``Final Technical Support Document for HWC MACT
Standards, Volume III: Selection of MACT Standards and
Technologies,'' July 1999 for a discussion of the approximate
equivalency.
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However, we now conclude that basing the floor on the 1971 New
Source Performance Standard is the most appropriate approach. Cement
kilns achieve the 1971 New Source Performance Standard with well-
designed and properly operated fabric filters and electrostatic
precipitators. Since approximately 20% of hazardous waste burning
cement kilns now are subject to the 1971 New Source Performance
Standard, consideration of this existing federal regulation as a floor
is appropriate because greater than 12% of existing sources are
achieving it. The available emissions test data show a wide range of
particulate matter results--some emissions data are well below while
other data are at the 1971 New Source Performance Standard
level.130 Even though the hazardous waste burning cement
kiln particulate matter data span two orders of
magnitude,131 we have limited data on design parameters of
the particulate matter control device and could not identify a cause
(i.e., differentiate among control equipment) for the wide range in
particulate matter emissions. We thus believe that the variation
reflects normal operating variability. Therefore, the MACT floor
emission level for existing cement kilns is the 1971 New Source
Performance Standard.
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\130\ The variation in the particulate matter data is consistent
with data from nonhazardous waste burning cement kilns. We neither
expect nor have any data indicating that waste-burning operations
increase particulate matter emissions at a cement kiln. An estimated
30% of existing nonhazardous waste burning cement kilns are subject
to the requirements of the new Source Performance Standard for
cement plants. The particulate matter data for these kilns also
exhibit a wide range in measurements. (63 FR at 14198.)
\131\ USEPA, ``Final Technical Support Document for HWC MACT
Standards, Volume III: Selection of MACT Standards and
Technologies,'' July 1999.
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The New Source Performance Standard at Sec. 60.62 also specifies
that opacity must be monitored continuously and establishes an opacity
standard of 20 percent as a measure to ensure compliance with the
particulate matter standard. We are therefore also adopting this
opacity standard for today's rule.132 We are adopting it for
the final rule because: (1) We proposed to base the particulate matter
standard for hazardous waste burning cement kilns on the New Source
Performance Standard, and the opacity standard is an integral component
of that standard; and (2) we proposed to base the MACT particulate
matter standard for nonhazardous waste burning cement kilns on the New
Source Performance Standard and explicitly identified both the
particulate emission and opacity components of the standard. Hazardous
waste burning cement kiln stakeholders have commented on both the
nonhazardous waste and hazardous waste cement kiln proposed rules and
suggest that there is little or no difference in emissions from the two
classes of kilns and that they should be regulated the same. Although
we do not agree that emissions of all hazardous pollutants are the same
for both classes of kilns and should be regulated the same, we agree
that particulate
[[Page 52880]]
emissions are comprised largely of entrained raw material and are not
significantly affected by burning hazardous waste. Thus, we concur that
the standard for particulate matter should be the same for both classes
of sources and are therefore adopting the New Source Performance
Standard opacity standard for the final rule.133 In the NPRM
and the May 1997 NODA, we proposed to express the particulate matter
standard on a concentration basis rather than express it as the same
format as the 1971 New Source Performance Standard, which is a
production-based emission limit format. However, because we are not yet
requiring sources to document compliance with the particulate matter
standard by using a particulate matter continuous emissions monitoring
system in this final rule 134, we establish and express the
floor emission level equivalent to the 1971 New Source Performance
Standard. Thus, the particulate matter floor is 0.15 kg/Mg dry feed
based on the performance of a well-designed and operated fabric filter
or electrostatic precipitator.
---------------------------------------------------------------------------
\132\ Given that we adopt the New Source Performance Standard
for particulate matter and opacity for the MACT standards for
hazardous waste burning cement kilns, we exempt these sources from
the New Source Performance Standard to avoid duplicative regulation.
See Sec. 63.1204(h).
\133\ We are not adopting the opacity standard component of the
New Source Performance Standard for hazardous waste burning
lightweight aggregate kilns, however. This is because that opacity
standard (see Sec. 60.732) is a measure to ensure compliance with
the particulate emissions component of that standard, which is
substantially higher than the MACT standard that we promulgate
today. Thus, the NSPS opacity standard for lightweight aggregate
kilns would not be a useful measure of compliance with today's
particulate matter standard for lightweight aggregate kilns.
\134\ We anticipate rulemaking on a particulate matter
continuous emissions monitoring system requirement for hazardous
waste combustors in the near future. Under this rulemaking,
combustors would be required to document compliance with national
emission standards by complying with continuous emissions monitoring
system-based particulate matter levels that are being achieved by
sources equipped with MACT controls. See Part Five, Section VII.C.
for details.
---------------------------------------------------------------------------
Several commenters expressed concern in their comments to the NPRM
that the Agency identified separate, different MACT pools and
associated MACT controls for particulate matter, semivolatile metals,
and low volatile metals, even though all three are controlled, at least
in part, by a particulate matter control device. Commenters stated that
our approach is likely to result in three different design
specifications. We agree with the need to use the same pool for
particulate matter, semivolatile metals, and low volatile metals and
used the same initial MACT pool to establish the floor levels for these
pollutants. See Part Four, Section V for a detailed discussion of our
floor methodology.
We estimate that over 60 percent of cement kilns currently meet the
floor emission level. The national annualized compliance cost for
cement kilns to reduce particulate matter emissions to comply with the
floor level is $6.2 million for the entire hazardous waste burning
cement industry and will reduce nonenumerated metals and particulate
matter emissions by 1.1 Mg/yr and 873 Mg/yr, respectively, or over 30
percent from current baseline emissions.
b. What Are Our Beyond-the-Floor Considerations for Existing
Sources? In the proposal and May 1997 NODA, we considered a beyond-the-
floor level of 34 mg/dscm (0.015 gr/dscf) based on improved particulate
matter control. However, after examining the costs of such control and
the relatively low incremental reductions in air emissions that would
result, we determined that a beyond-the-floor standard would not likely
be cost-effective. (61 FR at 17393.)
Several commenters support a beyond-the-floor option for
particulate matter because some cement kilns are readily achieving
particulate matter levels well below the floor emission level based on
the New Source Performance Standard. Other commenters oppose a beyond-
the-floor option for cement kilns because of the high costs and
anticipated poor cost-effectiveness. In the final rule, we evaluated a
beyond-the-floor emission level for existing cement kilns to determine
if such a level would be appropriate.
Improved particulate matter control for existing cement kilns would
require the use of high efficiency electrostatic precipitators and
fabric filters. These may include fabric filters with low air-to-cloth
ratios, high performance fabrics, electrostatic precipitators with
large specific collection areas, and advanced control systems.
Currently, the majority of hazardous waste burning cement kilns use
electrostatic precipitators for particulate matter control and usually
achieve removal efficiencies greater than 99.8%. Cement kilns can meet
the MACT floor with well designed and properly operated particulate
matter control equipment that for many kilns may require only minor
system upgrades from their current systems. A beyond-the-floor
standard, however, would likely involve more than a minor system
upgrade, and may require new control equipment or retrofitting a
baghouse with new higher performance fabric materials. The total
annualized costs associated with such major system upgrades would be
significant, while only achieving modest incremental emissions
reductions in particulate matter and nonenumerated metals.
In the final rule, we considered a beyond-the-floor level of 34 mg/
dscm, approximately one-half the New Source Performance Standard, for
existing cement kilns based on improved particulate matter control. For
analysis purposes, improved particulate matter control entails the use
of higher quality fabric filter bag material. We then determined the
cost of achieving this level of particulate matter, with corresponding
reductions in the nonenumerated metals for which particulate matter is
a surrogate, to determine if this beyond-the-floor level would be
appropriate. The national incremental annualized compliance cost for
cement kilns to meet this beyond-the-floor level, rather than comply
with the floor controls, would be approximately $7.4 million for the
entire hazardous waste burning cement kiln industry and would provide
an incremental reduction in nonenumerated metals emissions nationally
beyond the MACT floor controls of 0.7 Mg/yr. Based on these costs of
approximately $10.7 million per additional Mg of nonenumerated metals
emissions removed, we conclude that this beyond-the-floor option for
cement kilns is not acceptably cost-effective nor otherwise justified.
Therefore, we do not adopt this beyond-the-floor standard. The
promulgated particulate matter standard for existing hazardous waste
burning cement kilns is the floor emission level of 0.15 kg/Mg dry feed
and opacity not to exceed 20 percent.
c. What Is the MACT Floor for New Sources? In the proposal, we
defined floor control based on the performance of a fabric filter with
an air-to-cloth ratio of less than 1.8 acfm/ft2. As discussed for
existing sources, we proposed the floor level based on the existing
cement kiln New Source Performance Standard. 61 FR at 17400. In the May
1997 NODA, we again considered basing the floor emission level on the
New Source Performance Standard and solicited comment on the two
alternatives to express the standard identical to those discussed above
for existing cement kilns. (62 FR at 24228.)
All cement kilns use fabric filters and electrostatic precipitators
to control particulate matter. As discussed earlier, we have limited
detailed information on the design and operation characteristics of
existing control equipment currently used by cement kilns. As a result,
we are unable to identify a specific design or technology that can
consistently achieve lower emission levels than the controls used by
cement kilns achieving the New Source Performance Standard. Cement
kilns meet the New Source Performance Standard with well-
[[Page 52881]]
designed and properly operated fabric filters and electrostatic
precipitators. Thus, floor control for new cement kilns is also a well-
designed and properly operated fabric filter and electrostatic
precipitator. As discussed for existing sources, we conclude that
expressing the floor based on the New Source Performance Standards is
appropriate for the final rule. Therefore, the MACT floor level for new
cement kilns is 0.15 kg/Mg dry feed and opacity not to exceed 20
percent.
d. What Are Our Beyond-the-Floor Considerations for New Sources? In
the April 1996 NPRM and May 1997 NODA, we considered a beyond-the-floor
standard based on improved particulate matter control to be consistent
with existing sources. However, we proposed that such a beyond-the-
floor level was not likely cost-effective.
As discussed for existing sources, we considered a beyond-the-floor
level of 34 mg/dscm, approximately one-half the New Source Performance
Standard, for new cement kilns based on improved particulate matter
control. For analysis purposes, improved particulate matter control
entails the use of higher quality fabric filter bag material. We then
determined the cost of achieving this level of particulate matter, with
corresponding reductions in the nonenumerated metals for which
particulate matter is a surrogate, to determine if this beyond-the-
floor level would be appropriate. The incremental annualized compliance
cost for one new large cement kiln to meet this beyond-the-floor level,
rather than comply with floor controls, would be approximately $309,000
and would provide an incremental reduction in nonenumerated metals
emissions of approximately 0.18 Mg/yr.135 For a new small
cement kiln, the incremental annualized compliance cost would be
approximately $120,000 and would provide an incremental reduction in
nonenumerated metals emissions of approximately 0.04 Mg/yr. Based on
these costs of approximately $1.7-3.0 million per additional Mg of
nonenumerated metals removed, we conclude that a beyond-the-floor
standard of 0.015 gr/dscf is not justified due to the high cost of
compliance and relatively small nonenumerated metals emission
reductions. Thus, the particulate matter standard for new cement kilns
is the floor level of 0.15 kg/Mg dry feed and opacity not to exceed 20
percent.
---------------------------------------------------------------------------
\135\ Based on the data available, the average emissions in sum
of the five nonenumerated metals from cement kilns using MACT
particulate matter control is approximately 80 g/dscm. To
estimate emission reductions of the nonenumerated metals, we assume
a linear relationship between a reduction in particulate matter and
these metals.
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5. What Are the Semivolatile Metals Standards?
Today's rule establishes standards for existing and new cement
kilns that limit semivolatile metals emissions to 240 and 180
g/dscm, respectively. The rationale for these standards is
discussed below.
a. What Is the MACT Floor for Existing Sources? In the April 1996
proposal, we defined floor control as a fabric filter with an air-to-
cloth ratio less than 2.1 acfm/ft 2 and a hazardous waste
feedrate level of 84,000 g/dscm, expressed as a maximum
theoretical emission concentration. The proposed floor emission level
was 57 g/dscm, based on the level a source with properly
designed and operated floor technology could achieve. In the proposed
rule, we also solicited comment on an alternative floor approach
whereby ``equivalent technology'' to MACT control is identified and
evaluated. This approach resulted in an emission level of 160
g/dscm (See 61 FR at 17395.) In the May 1997 NODA, we
discussed a floor methodology where we used a breakpoint analysis to
identify sources that were not using floor control with respect either
to semivolatile metals hazardous waste feedrate or emissions control.
Under this approach, we ranked semivolatile metals emissions data from
sources that were using MACT floor particulate matter control, i.e.,
sources achieving the New Source Performance Standard or better. We
identified the floor level as the test condition average associated
with the breakpoint source. Thus, sources with atypically high
emissions because of high semivolatile metals feedrates or poor
semivolatile metals control even though they appeared to be using floor
control for particulate matter were screened from the pool of sources
used to define the floor emission level. Based on this analysis, we
identified a floor level in the May 1997 NODA of 670 g/dscm.
(See 62 FR at 24228.)
As discussed previously in the methodology section, we use a
revised engineering evaluation and data analysis method to establish
the MACT floor for semivolatile metals based on the same underlying
data previously noticed for comment. The aggregate feedrate approach,
in conjunction with floor control for particulate matter, identified a
semivolatile metals floor emission level of 650 g/dscm.
In addition, several commenters stated strongly that the feedrate
of semivolatile metals in hazardous waste cannot be considered MACT
floor control in conjunction with particulate matter control. These
commenters believe that floor control for semivolatile metals is
control of particulate matter only. We disagree with these commenters
for reasons we discuss in Part Four, Section V of the preamble, mainly
that feedrate is currently control for hazardous waste combustors under
RCRA regulations, and conclude that control of the feedrate of
semivolatile metals in hazardous waste is floor control, in conjunction
with particulate matter control.
We estimate that approximately 60 percent of cement kilns currently
meet this floor level. The national annualized compliance cost for
cement kilns to reduce semivolatile metal emissions to comply with the
floor level is $1.3 million for the entire hazardous waste burning
cement industry and will reduce semivolatile metal emissions by 19.5
Mg/yr or 65 percent from current baseline emissions.
b. What Are Our Beyond-the-Floor Considerations for Existing
Sources? In the proposal, we considered a beyond-the-floor standard for
semivolatile metals based on improved particulate matter control below
the New Source Performance Standard. However, we concluded that a
beyond-the-floor standard would not be cost-effective, given that the
semivolatile metal floor level of 57 g/dscm alone resulted in
an estimated 94 percent semivolatile metal reduction in emissions. (see
61 FR at 17396.) In the May 1997 NODA, we considered a lower
particulate matter emissions level of 0.015 gr/dscf, based on improved
particulate matter control, as a beyond-the-floor standard to further
reduce semivolatile and low volatile metals. Even though we did not
quantify cost-effectiveness values, we expressed concern that a beyond-
the-floor standard would not likely be cost-effective. (see 62 FR at
24229.)
Commenters believed there were several control techniques that
should be considered, therefore, we identified three potential beyond-
the-floor control techniques in developing the final rule: (1) Limiting
the feedrate of semivolatile metals in hazardous waste; (2) improved
particulate matter control; and (3) limiting the feedrate of
semivolatile metals in raw materials. We conclude that a beyond-the-
floor standard is warranted based on limiting the feedrate of
semivolatile metals in hazardous waste. The results of each analysis
are discussed below.
i. Limiting the Feedrate of Semivolatile Metals in Hazardous Waste.
Under this approach, we selected a beyond-the-floor emission level of
240
[[Page 52882]]
g/dscm from among the range of possible levels that reflect
improved feedrate control. This emission level represents a significant
increment of emission reduction from the floor of 650 g/dscm,
it is within the range of levels that are likely to be reasonably
achievable using feedrate control, and it is consistent with the
incinerator standard thereby advancing a potential policy objective of
essentially common standards among combustors of hazardous waste.
The national incremental annualized compliance cost for the
remaining cement kilns to meet this beyond-the-floor level, rather than
comply with the floor controls, would be approximately $2.7 million for
the entire hazardous waste burning cement kiln industry and would
provide an incremental reduction, beyond emissions at the MACT floor,
in semivolatile metal emissions nationally of 5.5 Mg/yr. The cost-
effectiveness of this standard would be approximately $500,000 per
additional Mg of semivolatile metals removed. Notwithstanding the
relatively poor cost-effectiveness of this standard on a dollar per Mg
removed basis, we conclude that additional beyond-the-floor control of
the feedrate of semivolatile metals in hazardous waste to achieve an
emission level of 240 g/dscm is warranted because this
standard would reduce lead and cadmium emissions which are particularly
toxic hazardous air pollutants. See Health Human Effects discussion in
USEPA, ``Technical Background Document for HWC MACT Standards: Health
and Ecological Risk Assessment'', July 1999. Further, approximately 90%
of the lead and cadmium fed to the cement kiln is from the hazardous
waste,136 not the raw material (about 9%) or coal (about
1%). We are willing to accept a more marginal cost-effectiveness to
ensure that hazardous waste combustion sources are using the best
controls for pollutants introduced almost exclusively for the burning
of hazardous waste. We do so to provide a strong incentive for waste
minimization of lead and cadmium sent for combustion. By providing
stringent limits, we can help assure that hazardous waste with lead
does not otherwise move from better controlled units in other
subcategories to units in this subcategory because of a lesser degree
of control. Moreover, this beyond-the-floor semivolatile metal standard
supports our Children's Health Initiative in that lead emissions, which
are of highest significance to children's health, will be reduced by
another 20-25 percent from today's baseline. As part of this
initiative, we are committed to reducing lead emissions wherever and
whenever possible. Finally, this beyond-the-floor standard is
consistent with European Union standards for hazardous waste
incinerators of approximately 200 g/dscm for lead and cadmium
combined. For all these reasons, we accept the cost-effectiveness of
this level of feedrate control and adopt a beyond-the-floor standard of
240 g/dscm for existing cement kilns.
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\136\ USEPA, ``Final Technical Support document for HWC MACT
Standards, Volume III: Selection of MACT Standards and
Technologies'', July 1999.
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Additionally, we received comments shortly before promulgation from
the cement kiln industry that expressed their achievability and
economic concerns with a beyond-the-floor standard in the range of 240
g/dscm based on limiting the feedrate of semivolatile metals
in the hazardous waste. We considered their comments in adopting the
240 g/dscm beyond-the-floor standard and included a copy of
their November 18, 1998 presentation to the Office of Management and
Budget in the docket along with our responses to their concerns, many
of which are addressed above.
ii. Improved Particulate Matter Control. We also evaluated improved
particulate matter control as a beyond-the-floor control option for
improved semivolatile metals control. Cadmium and lead are volatile at
the high temperatures within the cement kiln itself, but typically
condense onto the fine particulate at control device temperatures,
where they are collected. As a result, control of semivolatile metals
emissions is closely associated with particulate matter control.
Examples of improved particulate matter control include the use of more
expensive fabric filter bags, optimizing the design and operation
features of the existing control equipment, and the addition to or the
replacement of control equipment with a new fabric filter.
We evaluated the costs to achieve a beyond-the-floor emission level
of 240 g/dscm based on improved particulate matter control.
The national incremental annualized compliance cost for cement kilns to
meet this beyond-the-floor level, rather the floor level, would be
approximately $4.1 million for the entire hazardous waste burning
cement kiln industry and would provide an incremental reduction in
semivolatile metal emissions beyond the MACT floor controls of 5.5 Mg/
yr. Because this beyond-the-floor control option would have a cost-
effectiveness of approximately $800,00 per additional Mg of
semivolatile metal removed, contrasted to a cost-effectiveness of
approximately $500,000 using hazardous waste feedrate control and
remove an identical amount of semivolatile metals, we conclude that
basing the beyond-the-floor standard on improved particulate matter
control is not warranted.
iii. Limiting the Feedrate of Semivolatile Metals in Raw Materials.
A source can achieve a reduction in semivolatile metal emissions by
substituting a feed material containing lower levels of lead and/or
cadmium for a primary raw material with higher levels of these metals.
We expect this beyond-the-floor option to be less cost-effective
compared to either of the options evaluated above. Cement kilns are
sited proximate to primary raw material supply and transporting large
quantities of an alternative source of raw material(s) is likely to be
cost-prohibitive. Therefore, we are not adopting a semivolatile metal
beyond-the-floor standard based on limiting the feedrate of
semivolatile metals in raw materials.137
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\137\ We, however, reject the proposition in comments that we
are without legal authority to regulate HAPs in raw materials
processed in cement kilns based on legislative history to the 1990
amendments. This legislative history is not reflected in the
statutory text, which unambiguously gives us that authority.
---------------------------------------------------------------------------
Thus, the promulgated semivolatile metals standard for existing
hazardous waste burning cement kilns is a beyond-the-floor standard of
240 g/dscm based on limiting the feedrate of semivolatile
metals in the hazardous waste.
c. What Is the MACT Floor for New Sources? In the proposal, we
defined floor control as a fabric filter with an air-to-cloth ratio
less than 2.1 acfm/ft 2 and a hazardous waste feedrate level
of 36,000 g/dscm, expressed as a maximum theoretical emission
concentration. The proposed floor emission level for new cement kilns
was 55 g/dscm. (See 61 FR at 17400.) In the May 1997 NODA, we
concluded that the floor control and emission level for existing
sources for semivolatile metals also would be appropriate for new
sources. Floor control was based on a combination of good particulate
matter control and limiting hazardous waste feedrate of semivolatile
metals. We used a breakpoint analysis of the semivolatile metal
emissions data to exclude sources achieving substantially poorer
semivolatile metal control than the majority of sources because of
atypically high semivolatile metals feedrates or poor emission control.
We established the floor level at the test condition average of the
breakpoint source: 670 g/dscm. (See 62 FR at 24229.)
As discussed above for existing sources, we developed the final
rule
[[Page 52883]]
using the aggregate feedrate approach to identify MACT floors for the
metals. See Methodology Section for detailed discussion of aggregate
feedrate approach. Using this approach, we establish the semivolatile
metal floor emission level for new sources at 180 g/dscm.
d. What Are Our Beyond-the-Floor Considerations for New Sources? In
the April 1996 NPRM and May 1997 NODA, we considered a semivolatile
metal beyond-the-floor emission level for new sources, but determined
that it would not be cost-effective.
For the final rule, we do not consider a beyond-the-floor level for
new cement kilns because the MACT floor for new cement kilns is already
lower than the beyond-the-floor emission standard for existing sources.
As a result, a beyond-the-floor standard for new cement kilns is not
warranted due to the likely significant costs of control and the
minimal incremental emissions reductions. In addition, our policy goal
of state of the art control of lead is achieved at the floor standard
for new sources. We, therefore, adopt a semivolatile metal floor
standard of 180 g/dscm for new hazardous waste burning cement
kilns.
6. What Are the Low Volatile Metals Standards?
We establish standards for existing and new cement kilns in today's
rule that limit low volatile metal emissions to 56 and 54 g/
dscm, respectively. The rationale for these standards is discussed
below.
a. What Is the MACT Floor tor Existing Sources? In the April 1996
NPRM, we defined floor control as either: (1) A fabric filter with an
air-to-cloth ratio less than 2.3 acfm/ft \2\ and a hazardous waste
feedrate level of 140,000 g/dscm, expressed as a maximum
theoretical emission concentration; or (2) an electrostatic
precipitator with a specific collection area of 350 ft \2\/kacfm and
the same hazardous waste feedrate level of 140,000 g/dscm. The
proposed floor level was 130 g/dscm. (See 61 FR at 17396.) In
the May 1997 NODA, we used a breakpoint analysis to identify sources
that were not using floor control with respect either to low volatile
metals hazardous waste feedrate or emissions control. Under this
approach, we ranked low volatile metals emissions data from sources
that were achieving the particulate matter floor of 69 mg/dscm or
better. We identified the floor level as the test condition average
associated with the breakpoint source. Thus, sources with atypically
high emissions because of high low volatile metals feedrates or poor
low volatile metals control, even though they were using floor control
for particulate matter, were screened from the pool of sources used to
define the floor emission level. The May 1977 NODA MACT floor level was
63 g/dscm. (See 62 FR at 24229.)
We received limited comments in response to the NPRM and May 1997
NODA concerning the low volatile metals floor standard. We received
comments, however, on several overarching issues including the
appropriateness of considering feedrate control of metals including low
volatile metals in hazardous waste as a MACT floor control technique
and the specific procedure of identifying breakpoints in arrayed
emissions data. These issues and our responses to them are discussed in
the floor methodology section in Part Four, Section V.
Today we use a revised engineering evaluation and data analysis
method to establish the MACT floor for low volatile metals on the same
underlying data previously noticed for comment. As explained earlier,
the aggregate feedrate approach, in conjunction with floor control for
particulate matter, replaces the breakpoint analysis for metals and
results in a low volatile metal floor emission level of 56 g/
dscm.
We estimate that over 76 percent of cement kilns in our data base
meet the floor level. The national annualized compliance cost for
cement kilns to reduce low volatile metal emissions to comply with the
floor level is $0.8 million for the entire hazardous waste burning
cement industry, and will reduce low volatile metal emissions by 0.2
Mg/yr or approximately 25 percent from current baseline emissions.
b. What Are Our Beyond-the-Floor Considerations for Existing
Sources? In the proposal, we considered a beyond-the-floor standard for
low volatile metals based on improved particulate matter control.
However, we concluded that a beyond-the-floor standard would not likely
be cost-effective based on the limited emissions reductions of low
volatility metals. In the May 1997 NODA, we considered a lower
particulate matter emissions level, based on improved particulate
matter control, as a beyond-the-floor standard with corresponding
beyond-the-floor reductions in low volatile and semivolatile metals.
Even though we did not quantify cost-effectiveness values, we expressed
concern that a beyond-the-floor standard would not likely be cost-
effective. (62 FR at 24229.)
For today's final rule, we identified three potential beyond-the-
floor techniques for control of low volatile metals: (1) Improved
particulate matter control; (2) limiting the feedrate of low volatile
metals in the hazardous waste; and (3) limiting the feedrate of low
volatile metals in the raw materials. We discuss the results of our
analysis of each option below.
Improved Particulate Matter Control. Our judgment is that a beyond-
the-floor standard based on improved particulate matter control would
be less cost-effective than a beyond-the-floor standard based on
limiting the feedrate of low volatile metals in the hazardous waste.
First, our data show that all cement kilns are already achieving
greater than a 99% system removal efficiency for low volatile metals,
with most attaining 99.99% removal. Thus, equipment retrofit costs for
improved control would be significant and result in only a small
increment in reduction of emissions. Our beyond-the-floor analysis for
semivolatile metals supports this conclusion. There, the semivolatile
metals analysis showed that the beyond-the-floor option based on
limiting the feedrate of semivolatile metals was approximately 30% more
cost-effective than a beyond-the-floor option based on improved
particulate matter control. We believe the low volatile metals would
require similar particulate matter control device retrofits at cement
kilns as for semivolatile metals. However, the total emissions
reduction achieved would be less because hazardous waste burning cement
kilns emit less low volatile metals than semivolatile metals. We do not
have any of the serious concerns present for semivolatile metals that
suggest we should accept a more marginal cost-effectiveness. Thus, we
conclude that a beyond-the-floor standard for low volatile metals based
on improved particulate matter control is not warranted.
Limiting the Feedrate of Low Volatile Metals in the Hazardous
Waste. We also considered a beyond-the-floor standard of 40 g/
dscm for low volatile metals based on additional feedrate control of
low volatile metals in the hazardous waste. This would reduce the floor
emission level by approximately 30 percent. Our investigation shows
that this beyond-the-floor option would achieve an incremental
reduction in low volatile metals of only 0.1 Mg/yr. Given that this
beyond-the-floor level would not achieve appreciable emissions
reductions, we conclude that cost-effectiveness considerations would
likely come into play suggesting that this beyond-the-floor standard is
not warranted.
[[Page 52884]]
Limiting the Feedrate of Low Volatile Metals in the Raw Materials.
Sources can achieve a reduction in low volatile metal emissions by
substituting a feed material containing lower levels of arsenic,
beryllium, and/or chromium for a primary raw material with higher
levels of these metals. We believe that this beyond-the-floor option
would be even less cost-effective than either of the options evaluated
above, however. Cement kilns are sited proximate to primary raw
material supply and transporting large quantities of an alternative
source of raw material(s) is likely to be cost-prohibitive. Therefore,
we do not adopt a low volatile metal beyond-the-floor standard based on
limiting the feedrate of low volatile metals in raw materials.
For the reasons discussed above, we do not adopt a beyond-the-floor
level for low volatile metals and establish the emission standard for
existing hazardous waste burning cement kilns at 56 g/dscm.
c. What Is the MACT Floor for New Sources? In the proposal, we
defined floor control as a fabric filter with an air-to-cloth ratio
less than 2.3 acfm/ft2 and a hazardous waste feedrate
control level of 25,000 g/dscm, expressed as a maximum
theoretical emission concentration. The proposed floor for new cement
kilns was 44 g/dscm. (61 FR at 17400.) In the May 1997 NODA,
we concluded that the floor control and emission level for existing
sources for low volatile metals would also be appropriate for new
sources. Floor control was based on a combination of good particulate
matter control and limiting hazardous waste feedrate of low volatile
metals. We used a breakpoint analysis of the low volatile metal
emissions data to exclude sources achieving substantially poorer low
volatile metal control than the majority of sources. We established the
floor level at the test condition average of the breakpoint source. The
NODA floor was 63 g/dscm. (62 FR at 24230.)
As discussed above for existing sources, in developing the final
rule we use the aggregate feedrate approach to identify MACT floors for
the metals and hydrochloric acid/chlorine gas in combination with MACT
floor control for particulate matter. Based on the low volatile metal
feedrate in hazardous waste from the single best performing cement kiln
using floor control for particulate matter, the MACT floor for new
hazardous waste burning cement kilns is 54 g/dscm.
d. What Are Our Beyond-the-Floor Considerations for New Sources? In
the proposal and May 1997 NODA, we considered a low volatile metal
beyond-the-floor level for new sources, but determined it would not be
cost effective. For reasons similar to those discussed for existing
sources, we do not believe that a beyond-the-floor standard is
warranted for new cement kilns due to the high expected compliance cost
and relatively low reductions in emissions of low volatile metals.
Therefore, we adopt a low volatile metals standard of 54 g/
dscm for new hazardous waste burning cement kilns.
7. What Are the Hydrochloric Acid and Chlorine Gas Standards?
In today's rule, we establish standards for existing and new cement
kilns that limit hydrochloric acid and chlorine gas emissions to 130
and 86 ppmv, respectively. The rationale for these standards is
discussed below.
a. What Is the MACT Floor for Existing Sources? In the proposal, we
identified floor control for hydrochloric acid/chlorine gas as feedrate
control of chlorine in the hazardous waste and proposed a floor
standard of 630 ppmv. (61 FR at 17396.) In the May 1997 NODA, we used a
data analysis method similar to that at proposal and discussed a floor
emission level of 120 ppmv. (62 FR at 24230.)
Some commenters to the May 1997 NODA expressed concern that cement
kilns may not be able to meet the hydrochloric acid/chlorine gas
standard while making low alkali cement. Commenters noted that chlorine
is sometimes added specifically to volatilize potassium and sodium
compounds that must be removed to produce low alkali cement. One
commenter manufacturing a low alkali cement submitted data showing a
large range in hydrochloric acid/chlorine gas emissions while operating
under varying conditions and production requirements. This commenter
stated that they may not be able to meet the NODA hydrochloric acid/
chlorine gas standard of 120 ppmv while making low alkali cement. We
conclude, however, that the data they submitted do not adequately
support this ultimate conclusion. The commenter's emissions data range
from 6 ppmv to 83 ppmv while operating under RCRA compliance testing
conditions. These emission levels are well below the final standard of
130 ppmv, and the expected operational range in this rule is 70% of the
standard. We conclude that the hydrochloric acid/chlorine gas standard
of 130 ppmv finalized today is readily achievable by all cement kilns
irrespective of the type of cement manufactured.
For today's rule, we use a revised engineering evaluation and data
analysis method to establish the MACT floor for hydrochloric acid and
chlorine gas on the same underlying data previously noticed for
comment. Using the aggregate feedrate approach discussed previously, we
establish a hydrochloric acid/chlorine gas floor emission level of 130
ppmv.
We estimate that approximately 88 percent of cement kilns in our
data base currently meet the floor level. The national annualized
compliance cost for cement kilns to reduce hydrochloric acid/chlorine
gas emissions to comply with the floor level is $1.4 million for the
entire hazardous waste burning cement industry and will reduce
hydrochloric acid/chlorine gas emissions by 383 Mg/yr or 12 percent
from current baseline emissions.
b. What Are Our Beyond-the-Floor Considerations for Existing
Sources? In the proposal, we defined beyond-the-floor control as wet
scrubbing with a 99 percent removal efficiency, but determined that a
beyond-the-floor standard would not be cost-effective. (61 FR at
17397.) In the May 1997 NODA, we identified a more stringent floor
standard and therefore reasoned that a beyond-the-floor standard based
on wet scrubbing would likely also not be cost-effective. (62 FR at
24230.)
For today's rule, we identified three potential beyond-the-floor
techniques for control of hydrochloric acid/chlorine gas emissions: (1)
Scrubbing; (2) limiting the feedrate of chlorine in the hazardous
waste; and (3) limiting the feedrate of chlorine in the raw materials.
We discuss our analysis of each option below.
Scrubbing. We continue to believe that a beyond-the-floor standard
based on dry or wet scrubbing is not likely to be cost-effective.
Cement kilns achieve control of hydrochloric acid/chlorine gas
emissions from alkaline raw materials in the kiln. Control
effectiveness varies among kilns based on the alkalinity of the raw
materials. Thus, the cement manufacturing process serves essentially as
a dry scrubber. We conclude, therefore, that the addition of a dry
scrubber will only marginally improve hydrochloric acid/chlorine gas
removal and is not warranted as beyond-the-floor control.
It is also our judgment that a beyond-the-floor standard based on
wet scrubbing is not warranted. The total estimated engineering
retrofit costs would be approximately equivalent to those identified at
proposal for this option. However, emissions reductions would be less
given that the final MACT floor level is more stringent than the
[[Page 52885]]
level proposed. Therefore, the cost-effectiveness of a beyond-the-floor
standard would be less attractive than the number we rejected at
proposal. As a result, we must reaffirm that conclusion here.
Limiting the Feedrate of Chlorine in the Hazardous Waste. We also
considered a beyond-the-floor standard for hydrochloric acid/chlorine
gas based on additional feedrate control of chlorine in the hazardous
waste. We are concerned, however, that cement kilns making low alkali
cement may not be able to achieve a beyond-the-floor standard by
controlling feedrate of chlorine in the hazardous waste. As noted
above, chlorine is sometimes added specifically to volatilize potassium
and sodium compounds that must be removed from the clinker to produce
low alkali cement. Based on limited data submitted by a cement facility
manufacturing low alkali cement, achievability of a beyond-the-floor
standard of 70 ppmv, representing a 45% reduction from the floor level,
may not be feasible for this source using feedrate control and others
by inference. Therefore, we conclude that a beyond-the-floor standard
based on chlorine feedrate control in the hazardous waste is not
appropriate.
Limiting the Feedrate of Chlorine in the Raw Materials. A source
can achieve a reduction in hydrochloric acid/chlorine gas emissions by
substituting a feed material containing lower levels of chlorine for a
primary raw material with higher levels of chlorine. This beyond-the-
floor option is less cost-effective compared to the scrubbing options
evaluated above because cement kilns are sited proximate to the primary
raw material supply and transporting large quantities of an alternative
source of raw material(s) is not technically achievable. Therefore, we
do not adopt a hydrochloric acid/chlorine gas beyond-the-floor standard
based on limiting the feedrate of chlorine in raw materials.
In summary, we establish the hydrochloric acid/chlorine gas
standard for existing hazardous waste burning cement kilns at the floor
level of 130 ppmv.
c. What Is the MACT Floor for New Sources? At proposal, we defined
floor control for new sources as hazardous waste feedrate control for
chlorine and the proposed floor level was 630 ppmv. (See 61 FR at
17401.) In the May 1997 NODA, we concluded that the floor control and
emission level for existing sources for hydrochloric acid/chlorine gas
would also be appropriate for new sources. Floor control was based on
limiting hazardous waste feedrates of chlorine. After screening out
some data with anomalous system removal efficiencies compared to the
majority of sources, we established the floor level at the test
condition average of the breakpoint source. We identified a floor level
for new kilns of 120 ppmv. (See 62 FR at 24230.)
As discussed above for existing sources, in developing the final
rule, we use the aggregate feedrate approach to identify MACT floors
for hydrochloric acid/chlorine gas. The resulting MACT emissions floor
for new hazardous waste burning cement kilns is 86 ppmv.
d. What Are Our Beyond-the-Floor Considerations for New Sources? In
the proposal, we considered a beyond-the-floor standard for new cement
kilns of 67 ppmv based on wet scrubbing and concluded that it would not
be cost-effective. In the May 1997 NODA, we also concluded that a
beyond-the-floor standard based on wet scrubbing would likewise not be
cost-effective. Considering the level of the floor standard for new
kilns, we do not believe that a more stringent beyond-the-floor
standard is warranted for the final rule, especially considering our
concerns for cement kilns manufacturing low alkali cements.
In summary, we adopt the floor level of 86 ppmv as the standard for
hydrochloric acid/chlorine gas for new sources.
8. What Are the Hydrocarbon and Carbon Monoxide Standards for Kilns
Without By-Pass Sampling Systems? 138
---------------------------------------------------------------------------
\138\ See USEPA, ``Final Technical Support Document for
Hazardous Waste Combustor MACT Standards, Volume I: Description of
Source Categories,'' July 1999, for further explanation of by-pass
and midkiln sampling systems. Hydrocarbon and carbon monoxide
standards for kilns equipped with by-pass sampling systems are
discussed in Section VI.D.9 f the text.
---------------------------------------------------------------------------
See Sec. 63.1205(a)(5) and (b)(5).
In today's rule, we establish hydrocarbon and carbon monoxide
standards for new and existing cement kilns without by-pass sampling
systems as surrogates to control emissions of nondioxin organic
hazardous air pollutants. The standards for existing sources limit
hydrocarbon or carbon monoxide concentrations to 20 ppmv \139\ or 100
ppmv, \140\ respectively. The standards for new sources limit: (1)
Hydrocarbons to 20 ppmv; or (2) carbon monoxide to 100. New, greenfield
\141\ kilns that elect to comply with the 100 ppmv carbon monoxide
standard, however, must also comply with a 50 ppmv \142\ hydrocarbon
standard. New and existing sources that elect to comply with the 100
ppmv carbon monoxide standard, including new greenfield kilns that
elect to comply with the carbon monoxide standard and 50 ppmv
hydrocarbon standard, must also demonstrate compliance with the 20 ppmv
hydrocarbon standard during the comprehensive performance test.\143\
(See Part Four, Section IV.B of the preamble for the rationale for this
requirement.) We discuss the rationale for these standards below.
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\139\ Hourly rolling average, reported as propane, dry basis,
and corrected to 7% oxygen.
\140\ Hourly rolling average, dry basis, corrected to 7% oxygen.
\141\ A greenfield cement kiln is a kiln that commenced
construction or reconstruction after April 19, 1996 at a site where
no cement kiln previously existed, irrespective of the class of kiln
(i.e., nonhazardous waste or hazardous waste burning). A newly
constructed or reconstructed cement kiln at an existing site would
not be classified as a greenfield cement kiln, and would be subject
to the same carbon monoxide and hydrocarbon standards as an existing
cement kiln.
\142\ Thirty day block average, reported as propane, dry basis,
and corrected to 7 percent oxygen.
\143\ As discussed in Part 5, Section X.F, sources that feed
hazardous waste at a location other than the end where products are
normally discharged and where fuels are normally fired must comply
with the 20 ppmv hydrocarbon standard i.e., these sources do not
have the option to comply with the carbon monoxide standard).
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a. What Is the MACT Floor for Existing Sources? As discussed in
Part Four, Section II.B.2, we proposed limits on hydrocarbon emissions
for kilns without by-pass sampling systems as a surrogate to control
nondioxin organic hazardous air pollutants. In the April 1996 proposal
(61 FR at 17397), we identified a hydrocarbon floor emission level of
20 ppmv for cement kilns not equipped with by-pass sampling systems,
and proposed that floor control be based on the current federally-
enforceable RCRA boiler and industrial furnace standards, control of
organics in raw materials coupled with operating under good combustion
practices to minimize fuel-related hydrocarbon. In the May 1997 NODA,
we also indicated that this approach was appropriate.
Some commenters stated that a carbon monoxide limit of 100 ppmv was
necessary for these cement kilns to better control organic hazardous
air pollutants. Commenters also wrote that, alone, neither carbon
monoxide nor hydrocarbons is an acceptable surrogate for organic
hazardous air pollutant emissions. Additionally, commenters suggested
that by requiring both carbon monoxide and hydrocarbon limits, we would
further reduce emissions of organic hazardous air pollutants.
We conclude that continuous compliance with both a carbon monoxide
and hydrocarbon standard is unwarranted for the following reasons.
First, stack gas carbon monoxide levels are not a universally reliable
indicator
[[Page 52886]]
of combustion intensity and efficiency for kilns without by-pass
sampling systems. This is due to carbon monoxide generation by
disassociation of carbon dioxide to carbon monoxide at the high
sintering zone temperatures and evolution of carbon monoxide from the
trace organic constituents in raw material feedstock.\144\ (See 56 FR
at 7150, 7153-55). Thus, carbon monoxide can be a too conservative
surrogate for this type of kiln for potential emissions of hazardous
air pollutants from combustion of hazardous waste. There are other
sources of carbon monoxide unrelated to combustion of hazardous
waste.\145\
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\144\ Raw materials enter the upper end of the kiln and move
counter-current to the combustion gas. Thus, as the raw materials
are heated in the kiln, organic compounds can evolve from trace
levels of organics in the raw materials. These organic compounds can
be measured as hydrocarbons and, when only partially oxidized,
carbon monoxide. This process is not related to combustion of
hazardous waste or other fuels in the combustion zone at the other
end of the kiln.
\145\ Of course, if a source elects to comply with the carbon
monoxide standard, then we are more assured of good combustion
conditions in the combustion zone, and thus good control of organic
hazardous air pollutants that could be potentially emitted from
feeding hazardous waste in the combustion zone.
---------------------------------------------------------------------------
Second, requiring continuous compliance with both a carbon monoxide
and hydrocarbon emission limitation in the stack can be redundant for
control of organic emissions from combustion of hazardous waste
because: (1) Hydrocarbon alone is a direct and reliable surrogate for
organic hazardous air pollutants; and (2) in most cases carbon monoxide
is a conservative indicator of good combustion conditions and thus good
control of organic hazardous air pollutants. As discussed in the
following paragraphs, however, we have concluded that a source must
demonstrate compliance with the hydrocarbon standard during the
comprehensive performance test if it elects to continuously comply with
the carbon monoxide standard to ensure that carbon monoxide is an
adequate continuously monitored indicator of combustion efficiency. See
Part Four, Section IV of the preamble for a discussion of the merits of
using limits on stack gas concentrations of carbon monoxide and
hydrocarbon to control organic emissions.
One commenter suggested cement kilns be given the option to comply
with a carbon monoxide limit of 100 ppmv instead of the 20 ppmv
hydrocarbon limit. The commenter emphasized that this option is
currently allowed under the RCRA boiler and industrial furnace
regulations, and that it would be conservative because hydrocarbon
levels would always be below 20 ppmv when carbon monoxide levels are
below 100 ppmv. As discussed below, we agree that cement kilns should
be given the option to comply with either standard, but do not agree
that compliance with the carbon monoxide standard ensures compliance
with the hydrocarbon standard.
We have determined that it is necessary to require a source that
elects to continuously comply with the carbon monoxide standard to also
demonstrate compliance with the 20 ppmv hydrocarbon standard during the
comprehensive performance test. We concluded that this requirement is
necessary because we have limited data that shows a source can produce
high hydrocarbon emissions while simultaneously producing low carbon
monoxide emissions. This requirement to demonstrate compliance with the
hydrocarbon standard during the performance test is sufficient to
ensure that carbon monoxide alone is an appropriate continuously
monitored indicator of combustion efficiency. See Part 4, Section IV.B,
for a more detailed discussion. Consistent with this principle,
incinerators and lightweight aggregate kilns are also required to
demonstrate compliance with hydrocarbon standard during the
comprehensive performance test if they elect to comply with the carbon
monoxide standard.
In today's final rule, we are identifying a carbon monoxide level
of 100 ppmv and a hydrocarbon level of 20 ppmv as floor control for
existing sources because they are currently enforceable Federal
standards for hazardous waste burning cement kilns. See Sec. 266.104(b)
and (c). As current rules allow, sources would have the option of
complying with either limit. However, sources that elect to comply with
the carbon monoxide standard must also demonstrate compliance with the
hydrocarbon standard during the comprehensive performance test.
Given that these are current RCRA rules, all cement kilns without
by-pass sampling systems can currently achieve these emission levels.
Thus, we estimate no emissions reductions (or new costs) for compliance
with these floor levels.
b. What Are Our Beyond-the-Floor Considerations for Existing
Sources? In the April 1996 proposal, we identified beyond-the-floor
control levels for carbon monoxide and hydrocarbon in the main stack of
50 ppmv and 6 ppmv, respectively. (See 61 FR at 17397.) These beyond-
the-floor levels were based on the use of a combustion gas afterburner.
We indicated in the proposal, however, that the beyond-the-floor
control was not practical since no kilns currently achieved these
emission levels, and because of the high costs to retrofit a kiln with
an afterburner.
One commenter wrote that we rejected the 50 ppmv and 6 ppmv beyond-
the-floor carbon monoxide and hydrocarbon standards, respectively,
without providing any justification. In order to confirm the reasoning
discussed above, we have now estimated that the annualized cost for an
afterburner for cement kilns will range from $3-8 million dollars per
facility.\146\ As proposed, and as we reiterated in the May 1997 NODA a
beyond-the-floor standard based on an afterburner would be not be cost-
effective due to the high retrofit costs and minimal incremental
emissions reductions, and we do not adopt a beyond-the-floor standard
for existing cement kilns.
---------------------------------------------------------------------------
\146\ See `Final Technical Support Document for Hazardous Waste
Combustor MACT Standards, Volume V: Emission Estimates and
Engineering Costs'', February, 1999.
---------------------------------------------------------------------------
In summary, we adopt the floor emission levels as standards for
carbon monoxide, 100 ppmv, and hydrocarbons, 20 ppmv.
c. What Is the MACT Floor for New Sources? In the April 1996
proposal (see 61 FR at 17401) and the May 1997 NODA, we identified a
new source hydrocarbon floor emission level of 20 ppmv for new cement
kilns not equipped with by-pass sampling systems based on the current
Federally-enforceable BIF standards. The hydrocarbon limit is based on
control of organics in raw materials coupled with good combustion
practices.
In developing the final rule, we considered the comment discussed
above that the rule should allow compliance with either a carbon
monoxide standard of 100 ppmv or a hydrocarbon standard of 20 ppmv.
Given that this option is available under the current BIF rule for new
and existing sources, we now conclude that it represents MACT floor for
new sources, except as discussed below.
As discussed previously, we have also proposed MACT standards for
nonhazardous waste burning cement kilns. See 63 FR 14182, March 24,
1998. In that proposal, we determined that some existing sources have
used the combination of feed material selection, site location, and
feed material blending to optimize operations. We then concluded that
site selection based on availability of acceptable raw material
hydrocarbon content is a feasible approach to control hydrocarbon
emissions at new sources. See 63 FR at 14202-03. We proposed a new
source
[[Page 52887]]
floor hydrocarbon emission level of 50 ppmv at nonhazardous waste
burning Portland cement kilns because it is being consistently achieved
during thirty-day block averaging periods when high hydrocarbon content
raw materials are avoided. We have since promulgated a standard of 50
ppmv for hydrocarbons for new nonhazardous waste burning cement kilns.
64 FR 31898.
We now conclude for the same reasons that site selection is floor
control for new source, greenfield hazardous waste burning cement kilns
\147\ and that the floor hydrocarbon emission level is 50 ppmv.\148\
Sources must document compliance with this standard for each thirty-day
block period of operation. We reconcile this hydrocarbon floor level of
50 ppmv with the floor levels discussed above of 20 ppmv hydrocarbons
or 100 ppmv carbon monoxide by establishing the floor as follows. For
new source greenfield kilns, the floor is either: (1) 20 ppmv
hydrocarbons; or (2) 100 ppmv carbon monoxide and 50 ppmv hydrocarbons.
For other new sources not located at greenfield sites, the floor is
either 20 ppmv hydrocarbons or 100 ppmv carbon monoxide, which is
identical to the standards for existing sources.
---------------------------------------------------------------------------
\147\ At least one hazardous waste burning cement kiln in our
data base used raw material substitution to control hydrocarbon
emissions.
\148\ We concluded that this new source hydrocarbon standard of
50 ppms should not apply to new sources that are not located at
greenfield sites since these kilns are not capable of using site-
selection to control hydrocarbon emissions.
---------------------------------------------------------------------------
The combined 20 ppmv hydrocarbon and 100 ppmv carbon monoxide
standards control organic hazardous air pollutant emissions that
originate from the incomplete combustion of hazardous waste. The 50
ppmv hydrocarbon standard for new greenfield kilns controls organic
hazardous air pollutant emissions that originate from the raw material.
We conclude that the 50 ppmv hydrocarbon standard is necessary to deter
new kilns from siting at locations that have on-site raw material that
is high in organic content, since siting a cement kiln at such a
location could result in elevated hydrocarbon emissions.
We considered whether new greenfield kilns would be required to
monitor hydrocarbons continuously, or just document compliance with the
50 ppmv limit during the comprehensive performance test. We determined
that hydrocarbons must be continuously monitored because compliance
with the 100 ppmv carbon monoxide limit may not always ensure
compliance with the 50 ppmv hydrocarbon limit. This is because
hydrocarbons could potentially evolve from raw materials in the upper
drying zone end of the kiln under conditions that inhibit sufficient
oxidation of the hydrocarbons to form carbon monoxide.
As with existing sources, we are requiring new sources that elect
to continuously comply with the carbon monoxide standard, and new
greenfield sources that elect to comply with the carbon monoxide and 50
ppmv hydrocarbon standard, to also demonstrate compliance with the 20
ppmv hydrocarbon standard during the comprehensive performance test.
Consistent with this principle, incinerators and lightweight aggregate
kilns are also required to demonstrate compliance with the hydrocarbon
standard during the comprehensive performance test if they elect to
comply with the carbon monoxide standard.
d. What Are Our Beyond-the-Floor Considerations for New Sources? In
the April 1996 proposal, we identified beyond-the-floor emission levels
for carbon monoxide and hydrocarbon of 50 ppmv and 6 ppmv,
respectively, for new sources. (See 61 FR at 17401.) These beyond-the-
floor levels were based on the use of a combustion gas afterburner. We
indicated in the proposal, however, that beyond-the-floor control was
not practical since none of the kilns in our data base are achieving
these emission levels, and because of the high costs to retrofit kilns
with an afterburner. We reiterated in the May 1997 NODA that a beyond-
the-floor standard based on use of an afterburner would not be cost-
effective.
One commenter supported these beyond-the-floor standards for new
sources, but did not explain why these were considered to be
appropriate standards. As discussed above for existing sources, we
continue to believe that a beyond-the-floor standard based on use of an
afterburner would not be cost-effective.
In summary, we adopt the floor levels as standards for new sources.
For new source greenfield kilns, the standard monitored continuously is
either: (1) 20 ppmv hydrocarbons; or (2) 100 ppmv carbon monoxide and
50 ppmv hydrocarbons. For other new source kilns, the standard is
either 20 ppmv hydrocarbons or 100 ppmv carbon monoxide monitored
continuously. New sources that elect to comply with the carbon monoxide
standard, and new greenfield sources that elect to comply with the
carbon monoxide and 50 ppmv hydrocarbon standard, must also demonstrate
compliance with the 20 ppmv hydrocarbon standard, but only during the
comprehensive performance test.
9. What Are the Carbon Monoxide and Hydrocarbon Standards for Kilns
With By-Pass Sampling Systems? 149
---------------------------------------------------------------------------
\149\ This also includes cement kilns which have midkiln
sampling systems. See USEPA, ``Final Technical Support Document for
Hazardous Waste Combustor MACT Standards, Volume I: Description of
Source Categories,'' July 1999, for further explanation of by-pass
and midkiln sampling systems.
---------------------------------------------------------------------------
See Sec. 63.1204(a)(5) and (b)(5).
We establish carbon monoxide and hydrocarbon standards for existing
and new cement kilns with by-pass sampling systems as surrogates to
control emissions of nondioxin organic hazardous air
pollutants.150 Existing kilns are required to comply with
either a carbon monoxide standard of 100 ppmv or a hydrocarbon standard
of 10 ppmv on an hourly rolling average basis. Both standards apply to
combustion gas sampled in the by-pass or a midkiln sampling port that
samples representative kiln gas. Sources that elect to comply with the
carbon monoxide standard, however, must also document compliance with
the hydrocarbon standard during the comprehensive performance
test.151 See Part Four, Section IV.B of the preamble for the
rationale for this requirement.
---------------------------------------------------------------------------
\150\ As discussed in Part 5, Section X.F, cement kilns equipped
with bypass sampling systems that feed hazardous waste at a location
other than the end where products are normally discharged and at a
location downstream of the bypass sampling location (relative to the
combustion gas flow direction) must comply with the 20 ppmv main
stack hydrocarbon standard discussed in the previous section in lieu
of the bypass gas hydrocarbon standard.
\151\As discussed in Part 5, Section X.F, cement kilns that feed
hazardous waste at a location other than the end where products are
normally discharged and where fuels are normally fired must comply
wit the 10 ppmv hydrocarbon standard (i.e., these sources do not
have the option to comply with the carbon monoxide standard).
---------------------------------------------------------------------------
New kilns are subject to the same by-pass gas carbon monoxide and
hydrocarbon standards as existing sources. But, new, greenfield
152 kilns must also comply with a 50 ppmv hydrocarbon
standard continuously monitored in the main stack. Sources must
document compliance with this standard for each thirty-day block period
of operation.
---------------------------------------------------------------------------
\152\ A greenfield cement kiln is a kiln that commenced
construction or reconstruction after April 19, 1996 at a site where
no cement kiln previously existed, irrespective of the class of kiln
(i.e., nonhazardous waste or hazardous waste burning). A newly
constructed or reconstructed cement kiln at an existing site would
not be classified as a greenfield cement kiln, and would be subject
to the same carbon monoxide and hydrocarbon standards as an existing
cement kiln.
---------------------------------------------------------------------------
We discuss the rationale for adopting these standards below.
[[Page 52888]]
a. What Is the MACT Floor for Existing Sources? In the April 1996
proposal, we identified floor carbon monoxide and hydrocarbon emission
standards for by-pass gas of 100 ppmv and 6.7 ppmv, respectively. Floor
control was good combustion practices. (See 61 FR at 17397.) In the May
1997 NODA, we used an alternative data analysis method to identify a
hydrocarbon floor level of 10 ppmv.153 See 62 FR at 24230.
Our decision to use engineering information and principles to set the
proposed floor standard was based, in part, on the limited hydrocarbon
data in our data base. In addition, we reasoned that the hydrocarbon
levels being achieved in an incinerator, (i.e., 10 ppmv) are also being
achieved in a cement kiln's by-pass duct.154
---------------------------------------------------------------------------
\153\ The proposed hydrocarbon standard of 6.7 ppmv was based on
a statistical and breakpoint analysis. Today's final rule,
consistent with May 1997 NODA, instead uses engineering information
and principles to identify the floor hydrocarbon level of 10 ppmv.
\154\ See USEPA, ``Final Technical Support Document for
Hazardous Waste Combustor MACT Standards, Volume III: Selection of
MACT Standards and Technologies,'' February, 1999.
---------------------------------------------------------------------------
Some commenters stated that we did not have sufficient hydrocarbon
emissions data from cement kilns equipped with by-pass sampling systems
to justify a by-pass duct hydrocarbon standard. We disagree and
conclude that we have adequate data because the MACT data base includes
seven cement kilns that monitored hydrocarbons at the bypass sampling
location. These sources are achieving hydrocarbon levels of 10 ppmv or
less.155 The fact that these sources achieve hydrocarbon
levels below 10 ppmv supports our use of engineering information and
principles to set the floor limit at 10 ppmv.156
---------------------------------------------------------------------------
\155\ Four of these kilns have ceased hazardous waste
operations, and one of the kilns collected that data during time
periods other than Certification of Compliance testing.
\156\ We note that we could have elected to establish this 10
ppmv hydrocarbon standard as a beyond-the-floor standard rather than
a floor standard.
---------------------------------------------------------------------------
Many commenters questioned whether cement kilns with by-pass
sampling systems should comply with both a hydrocarbon and carbon
monoxide standard. Those in favor of requiring cement kilns to comply
with both standards wrote that neither carbon monoxide nor hydrocarbons
are sufficient surrogates for organic hazardous air pollutant
emissions. Commenters also noted that by requiring both a carbon
monoxide and hydrocarbon limit, we would achieve appropriate organic
hazardous air pollutant emission reductions. Other commenters wrote
that continuous compliance with both a hydrocarbon and a carbon
monoxide standard would be redundant and unnecessarily costly. We agree
with the latter view, in that requiring continuous compliance with both
standards for bypass gas is redundant for control of organic emissions
from combustion of hazardous waste because, as previously discussed:
(1) Hydrocarbon alone is a direct and reliable surrogate for organic
hazardous air pollutants; and (2) in most cases, carbon monoxide is a
conservative indicator of good combustion conditions and thus good
control of organic hazardous air pollutants. However, as discussed
earlier, we have concluded that a source must demonstrate compliance
with the hydrocarbon standard during the comprehensive performance test
if it elects to continuously comply with the carbon monoxide standard
to ensure that carbon monoxide is an adequate continuously monitored
indicator of combustion efficiency. See discussion in Part Four,
Section IV.B of the preamble for more discussion on this issue.
One commenter stated that due to some by-pass gas quenching
methods, and the need to correct for moisture and oxygen, it may not be
possible to accurately measure hydrocarbons to the level of the
proposed standard, i.e., 6.7 ppmv. We disagree with this reasoning
because, as explained in the technical support document, cement kiln
by-pass hydrocarbon levels should be reasonably achievable and
measurable by decreasing the span and increasing the calibration
frequency of the hydrocarbon monitor.157 We also note that a
cement kiln has the option to petition the Administrator for
alternative monitoring approaches under Sec. 63.8(f) if the source has
valid reasons why a total hydrocarbon monitor cannot be used to
document compliance.
---------------------------------------------------------------------------
\157\ See USEPA, ``Final Technical Support Document for
Hazardous Waste Combustor MACT Standards, Volume III: Selection of
MACT Standards and Technologies,'' February, 1999.
---------------------------------------------------------------------------
We conclude that floor control can achieve by-pass gas emission
levels of 100 ppmv for carbon monoxide and 10 ppmv for hydrocarbons. As
discussed in Part Four, Section IV.B, a source may comply with either
standard. If the source elects to comply with the carbon monoxide
standard, however, it must also demonstrate compliance with the
hydrocarbon standard during comprehensive performance testing.
We estimate that all cement kilns with by-pass sampling systems can
currently achieve the carbon monoxide floor of 100 ppmv. We also
estimate that approximately 97 percent of cement kilns with by-pass
sampling systems meet the hydrocarbon floor level of 10 ppmv. The
national annualized compliance cost for cement kilns to comply with the
floor level is $37K and hydrocarbon emissions will be reduced by 11 Mg/
yr, two percent from current baseline emissions .
b. What Are Our Beyond-the-Floor Considerations for Existing
Sources? In the April 1996 proposal, we identified a beyond-the-floor
control level for carbon monoxide and hydrocarbons in the main stack of
50 ppmv and 6 ppmv, respectively, based on the use of a combustion gas
afterburner. (See 61 FR at 17399.) We indicated in the proposal that
this beyond-the-floor level was not practical, however, since none of
the kilns currently achieve these emission levels and because of the
high costs of retrofitting kilns with an afterburner. We estimate that
the annualized cost for each cement kiln to operate afterburners range
from three to eight million dollars.158 We continue to
believe that it is not cost-effective based on the high retrofit costs
and minimal incremental emissions reductions to adopt these beyond-the-
floor standards.
---------------------------------------------------------------------------
\158\ See ``Final Technical Support Document for Hazardous Waste
Combustor MACT Standards, Volume V: Emission Estimates and
Engineering Costs'', February, 1999.
---------------------------------------------------------------------------
In the April 1996 NPRM, we also considered limiting main stack
hydrocarbon emissions to a beyond-the-floor level of 20 ppmv based on
the use of a low-organic raw material.159 This was in
addition to floor controls limiting carbon monoxide and/or hydrocarbon
levels in the by-pass. See 61 FR at 17398. We considered this beyond-
the-floor option to address concerns that: (1) organics desorbed from
raw materials may contain hazardous air pollutants, even absent any
influence from burning hazardous waste; and, (2) it is reasonable to
hypothesize that the chlorine released from burning hazardous waste can
react with the organics desorbed from the raw material to form
generally more toxic chlorinated hazardous air pollutants. Many
commenters supported this approach. For the reasons discussed below,
however, we conclude it is not appropriate to adopt this beyond-the-
[[Page 52889]]
floor hydrocarbon standard for existing sources.
---------------------------------------------------------------------------
\159\ The definition of floor control for existing cement kilns
equipped with by-pass sampling systems does not include the use of
low organic raw material. Although we have limited data indicating
that some kilns used low organic raw material to control hydrocarbon
emissions, there are enough facilities using this method of control
to establish it as a floor control for existing sources.
---------------------------------------------------------------------------
Also, many commenters stated that we should establish a main stack
hydrocarbon standard because, as stated above, hazardous waste
combustion byproducts from cement kilns, particularly chlorine, can
react with organic compounds desorbed from raw materials to form
hazardous air pollutants. Commenters believe that an additional main
stack hydrocarbon emission standard would limit the emissions of
chlorinated organic hazardous air pollutants that are generated due to
the interaction of the hazardous waste combustion byproducts and the
organics desorbed from the raw material.
We disagree that a main stack hydrocarbon emission limit is an
appropriate beyond-the-floor control for existing sources. First, we do
not believe it is cost-effective to require an existing kiln to
substitute its raw material with an off-site raw
material.160 Cement kilns are sited proximate to the primary
raw material supply and transporting large quantities of an alternative
source of raw material(s) is likely to be very costly. Second,
establishing a main stack hydrocarbon limit for existing sources is
likely to be counter-productive in controlling organic hazardous air
pollutants. It may compel the operator to avoid the unacceptable costs
of importing low organic raw material by increasing back-end kiln
temperatures to oxidize organics desorbed from raw material, thus
lowering hydrocarbon levels. This increase in temperature may result in
increased dioxin formation and is counter to our dioxin control
strategy. Third, it is debatable whether there is a strong relationship
between chlorine feedrates and chlorinated organic hazardous air
pollutant emissions, as is suggested by commenters.161
Finally, we anticipate that any potential risks associated with the
possible formation of these chlorinated hazardous air pollutants at
high hydrocarbon emission levels can be adequately addressed in a site-
specific risk assessment conducted as part of the RCRA permitting
process. This increased potential for emissions of chlorinated
hazardous air pollutants is not likely to warrant evaluation via a
site-specific risk assessment under RCRA, however, unless main stack
hydrocarbon levels are substantially higher than the 20 ppmv limit
currently applicable under RCRA for cement kilns not equipped with by-
pass systems.
---------------------------------------------------------------------------
\160\ We did not quantify actual costs associated with raw
material substitution due to the lack of information.
\161\ It is true that some studies have shown a relationship
between chlorine levels in the flue gas and the generation of
chlorobenzene in cement kiln emissions: the more chlorine, the more
chlorobenzene is generated. Some full-scale tests, however, have
shown that there is no observable or consistent trend when comparing
``baseline'' (i.e., nonhazardous waste operation) organic hazardous
air pollutant emissions with organic hazardous air pollutant
emissions associated with hazardous waste operations, as well as
comparing hazardous waste conditions with varying levels of
chlorine. See USEPA, ``Final Technical Support Document for
Hazardous Waste Combustor MACT Standards, Volume III: Selection of
MACT Standards and Technologies,'' July 1999, for further
discussion.
---------------------------------------------------------------------------
In summary, we adopt the floor levels as standards for carbon
monoxide, 100 ppmv, and hydrocarbons, 10 ppmv. As discussed above, a
source may comply with either standard. If the source elects to comply
with the carbon monoxide standard, however, it must also demonstrate
compliance with the hydrocarbon standard during comprehensive
performance testing.
c. What Is the MACT Floor for New Sources? In the April 1996
proposal, we identified new source floor standards for carbon monoxide
and hydrocarbon emissions in the by-pass of 100 ppmv and 6.7 ppmv,
respectively. We identified good combustion practices as floor control.
(See 61 FR at 17401.) In the May 1997 NODA, we used an alternative data
analyses method, in part, to identify an alternative new source
hydrocarbon floor level. (See 62 FR at 24230.) As a result of this
analysis and the use of engineering information and principles, we
identified a floor hydrocarbon emission level of 10 ppmv in the by-pass
for new cement kilns. We continue to believe that the new source
hydrocarbon floor methodology discussed in the May 1997 NODA, and the
new source carbon monoxide floor methodology discussed in the April
1996 proposal, are appropriate. Therefore, we adopt these floor
emission levels for by-pass gas in today's final rule.
We also establish a 50 ppmv hydrocarbon floor level for the main
stack of new greenfield kilns. As discussed above (Part Four, Section
VII.8.c), we concluded during development of the final rule that some
cement kilns are currently controlling their feed material selection,
site location, and feed material blending to optimize operations.
Because these controls can be used to control hydrocarbon content of
the raw material and, thus, hydrocarbon emissions in the main stack,
they represent floor control for main stack hydrocarbons for new
sources.162 We established a floor hydrocarbon emission
level of 50 ppmv because it is being consistently achieved during
thirty-day block averaging periods when high hydrocarbon content raw
materials are avoided.
---------------------------------------------------------------------------
\162\ At least one hazardous waste burning cement kiln in our
data base used raw material substitution to control hydrocarbon
emissions.
---------------------------------------------------------------------------
d. What Are Our Beyond-the-Floor Considerations for New Sources? In
the April 1996 proposal, we identified main stack beyond-the-floor
emission levels for carbon monoxide and hydrocarbon of 50 ppmv and 6
ppmv, respectively, for new sources. (See 61 FR at 17401.) These
beyond-the-floor levels were based on the use of a combustion gas
afterburner. We indicated in the proposal, however, that beyond-the-
floor control was not practical since none of the kilns in our data
base are achieving these emission levels, and because of the high costs
to retrofit kilns with an afterburner. We reiterated in the May 1997
NODA, that a beyond-the-floor standard based on use of an afterburner
would not be cost-effective.
One commenter wrote that we rejected these beyond-the-floor carbon
monoxide and hydrocarbon standards without providing any justification.
Another commenter supported these beyond-the-floor standards for new
sources. As discussed above (in greater detail) for existing sources,
we continue to believe that a beyond-the-floor standard based on use of
an afterburner would not be cost-effective.
In the April 1996 proposal, we considered limiting main stack
hydrocarbon emissions at new sources equipped with by-pass sampling
systems to a beyond-the-floor level of 20 ppmv.163 This
addressed concerns that: (1) Organics desorbed from raw materials
contain hazardous air pollutants, even absent any influence from
burning hazardous waste; and (2) it is reasonable to hypothesize that
the chlorine released from burning hazardous waste can react with the
organics desorbed from the raw material to form generally more toxic
chlorinated hazardous air pollutants. Although not explicitly stated,
beyond-the-floor control would have been control of feed material
selection, site location, and feed material blending to control the
hydrocarbon content of the raw material and, thus, hydrocarbon
emissions in the main stack. As discussed above, however, we adopt
today a main stack hydrocarbon floor standard of 50 ppmv for newly
constructed greenfield cement kilns equipped with by-pass systems. We
are not adopting a main stack beyond-the floor hydrocarbon standard of
20 ppmv for these kilns because we
[[Page 52890]]
are concerned that it may not be readily achievable using beyond-the-
floor control.
---------------------------------------------------------------------------
\163\ This was in addition to limiting hydrocarbon and/or carbon
monoxide at the by-pass sampling location.
---------------------------------------------------------------------------
In summary, we establish the following standards for new sources
based on floor control: (1) By-pass gas emission standards for carbon
monoxide and hydrocarbons of 100 ppmv and 10 ppmv, respectively;
164 and (2) a main stack hydrocarbon standard of 50 ppmv at
greenfield sites.
---------------------------------------------------------------------------
\164\ A source may comply with either bypass gas standard. If
the source elects to comply with the carbon monoxide standard,
however, it must also demonstrate compliance with the hydrocarbon
standard during comprehensive performance testing.
---------------------------------------------------------------------------
10. What Are the Destruction and Removal Efficiency Standards?
We establish a destruction and removal efficiency (DRE) standard
for existing and new cement kilns to control emissions of organic
hazardous air pollutants other than dioxins and furans. Dioxins and
furans are controlled by separate emission standards. See discussion in
Part Four, Section IV.A. The DRE standard is necessary, as previously
discussed, to complement the carbon monoxide and hydrocarbon emission
standards, which also control these hazardous air pollutants.
The standard requires 99.99 percent DRE for each principal organic
hazardous constituent (POHC), except that 99.9999 percent DRE is
required if specified dioxin-listed hazardous wastes are burned. These
wastes are listed as--F020, F021, F022, F023, F026, and F027--RCRA
hazardous wastes under part 261 because they contain high
concentrations of dioxins.
a. What Is the MACT Floor for Existing Sources? Existing sources
are currently subject to DRE standards under Sec. 266.104(a) that
require 99.99 percent DRE for each POHC, except that 99.9999 percent
DRE is required if specified dioxin-listed hazardous wastes are burned.
Accordingly, these standards represent MACT floor. Since all hazardous
waste cement kilns are currently subject to these DRE standards, they
represent floor control, i.e., greater than 12 percent of existing
sources are achieving these controls.
b. What Are Our Beyond-the-Floor Considerations for Existing
Sources? Beyond-the-floor control would be a requirement to achieve a
higher percentage DRE, for example, 99.9999 percent DRE for POHCs for
all hazardous wastes. A higher DRE could be achieved by improving the
design, operation, or maintenance of the combustion system to achieve
greater combustion efficiency.
Sources will not incur costs to achieve the 99.99% DRE floor
because it is an existing RCRA standard . A substantial number of
existing hazardous waste combustors are not likely to be routinely
achieving 99.999% DRE, however, and most are not likely to be achieving
99.9999% DRE. Improvements in combustion efficiency will be required to
meet these beyond-the-floor DREs. Improved combustion efficiency is
accomplished through better mixing, higher temperatures, and longer
residence times. As a practical matter, most combustors are mixing-
limited. Thus, improved mixing is necessary for improved DREs. For a
less-than-optimum burner, a certain amount of improvement may typically
be accomplished by minor, relatively inexpensive combustor
modifications--burner tuning operations such as a change in burner
angle or an adjustment of swirl--to enhance mixing on the macro-scale.
To achieve higher and higher DREs, however, improved mixing on the
micro-scale may be necessary requiring significant, energy intensive
and expensive modifications such as burner redesign and higher
combustion air pressures. In addition, measurement of such DREs may
require increased spiking of POHCs and more sensitive stack sampling
and analysis methods at added expense.
Although we have not quantified the cost-effectiveness of a beyond-
the-floor DRE standard, we do not believe that it would be cost-
effective. For reasons discussed above, we believe that the cost of
achieving each successive order-of-magnitude improvement in DRE will be
at least constant, and more likely increasing. Emissions reductions
diminish substantially, however, with each order of magnitude
improvement in DRE. For example, if a source were to emit 100 gm/hr of
organic hazardous air pollutants assuming zero DRE, it would emit 10
gm/hr at 90 percent DRE, 1 gm/hr at 99 percent DRE, 0.1 gm/hr at 99.9
percent DRE, 0.01 gm/hr at 99.99 percent DRE, and 0.001 gm/hr at 99.999
percent DRE. If the cost to achieve each order of magnitude improvement
in DRE is roughly constant, the cost-effectiveness of DRE decreases
with each order of magnitude improvement in DRE. Consequently, we
conclude that this relationship between compliance cost and diminished
emissions reductions associated with a more stringent DRE standard
suggests that a beyond-the-floor standard is not warranted.
c. What Is the MACT Floor for New Sources? The single best
controlled source, and all other hazardous waste cement kilns, are
subject to the existing RCRA DRE standard under Sec. 266.104(a).
Accordingly, we adopt this standard as the MACT floor for new sources.
d. What Are Our Beyond-the-Floor Considerations for New Sources? As
discussed above, although we have not quantified the cost-effectiveness
of a more stringent DRE standard, diminishing emissions reductions with
each order of magnitude improvement in DRE suggests that cost-
effectiveness considerations would likely come into play. We conclude
that a beyond-the-floor standard is not warranted.
VIII. What Are the Standards for Existing and New Hazardous Waste
Burning Lightweight Aggregate Kilns?
A. To Which Lightweight Aggregate Kilns Do Today's Standards Apply?
The standards promulgated today apply to each existing,
reconstructed, and newly constructed lightweight aggregate plant where
hazardous waste is burned in the kiln. These standards apply to major
source and area source lightweight aggregate facilities. Lightweight
aggregate kilns that do not engage in hazardous waste burning
operations are not subject to this NESHAP; however, these kilns will be
subject to future MACT standards for the Clay Products source category.
B. What Are the Standards for New and Existing Hazardous Waste Burning
Lightweight Aggregate Kilns?
1. What Are the Standards for Lightweight Aggregate Kilns?
In this section, the basis for the emissions standards for
hazardous waste burning lightweight aggregate kilns is discussed. The
kiln emission limits apply to the kiln stack gases from lightweight
aggregate plants that burn hazardous waste. The emissions standards are
summarized below:
[[Page 52891]]
Standards for Existing and New Lightweight Aggregate Kilns
------------------------------------------------------------------------
Hazardous air pollutant or Emissions standard \1\
hazardous air pollutant -------------------------------------------
surrogate Existing sources New sources
------------------------------------------------------------------------
Dioxin/furan................ 0.20 ng TEQ/dscm; or 0.20 ng TEQ/dscm; or
0.40 ng TEQ/dscm 0.40 ng TEQ/dscm
and rapid quench of and rapid quench of
the flue gas at the the flue gas at the
exit of the kiln to exit of the kiln to
less than 400 deg.F. less than 400
deg.F.
Mercury..................... 47 g/dscm.. 43 g/dscm.
Particulate matter.......... 57 mg/dscm (0.025 gr/ 57 mg/dscm (0.025 gr/
dscf). dscf).
Semivolatile metals \2\..... 250 g/dscm. 43 g/dscm.
Low volatile metals \3\..... 110 g/dscm. 110 g/dscm.
Hydrochloric acid/chlorine 230 ppmv............ 41 ppmv.
gas.
Hydrocarbons 2,3............ 20 ppmv (or 100 ppmv 20 ppmv (or 100 ppmv
carbon monoxide). carbon monoxide).
Destruction and removal For existing and new sources, 99.99% for
efficiency. each principal organic hazardous
constituent (POHC) designated. For
sources burning hazardous wastes F020,
F021, F022, F023, F026, or F027, 99.9999%
for each POHC designated.
------------------------------------------------------------------------
\1\ All emission levels are corrected to 7% O2, dry basis.
\2\ Hourly rolling average. Hydrocarbons are reported as propane.
\3\ Lightweight aggregate kilns that elect to continuously comply with
the carbon monoxide standard must demonstrate compliance with the
hydrocarbon standard of 20 ppmv during the comprehensive performance
test.
2. What Are the Dioxin and Furan Standards?
In today's rule, we establish a standard for new and existing
lightweight aggregate kilns that limits dioxin/furan emissions to
either 0.20 ng TEQ/dscm; or 0.40 ng TEQ/dscm and rapid quench of the
flue gas at the exit of the kiln to less than 400 deg.F. Our rationale
for adopting these standards is discussed below.
a. What Is the MACT Floor for Existing Sources? In the April 1996
proposal, we had dioxin/furan emissions data from only one lightweight
aggregate kiln and pooled that data with the dioxin/furan data for
hazardous waste burning cement kilns to identify the MACT floor
emission level. We stated that it is appropriate to combine the two
data sets because they are adequately representative of general dioxin/
furan behavior and control in either type of kiln. Consequently, floor
control and the floor emission level for lightweight aggregate kilns
were the same as for cement kilns. We proposed a floor emission level
of 0.20 ng TEQ/dscm, or temperature at the inlet to the fabric filter
not to exceed 418 deg.F. (61 FR at 17403.)
Several commenters opposed our proposed approach of pooling the
lightweight aggregate kiln data with the cement kiln dioxin/furan data
for the MACT floor analysis. In order to respond to commenter concerns,
we obtained additional dioxin/furan emissions data from lightweight
aggregate kiln sources. In a MACT reevaluation discussed in the May
1997 NODA, we presented an alternative data analysis method to identify
floor control and the floor emission level. In that NODA, dioxin/furan
floor control was defined as temperature control not to exceed
400 deg.F at the inlet to the fabric filter. That analysis resulted in
a floor emission level of 0.20 ng TEQ/dscm, or 4.1 ng TEQ/dscm and
temperature at the inlet to the fabric filter not to exceed 400 deg.F.
(62 FR at 24231.) An emission level of 4.1 ng TEQ/dscm represents the
highest single run from the test condition with the highest run
average. We concluded that 4.1 ng TEQ/dscm was a reasonable floor
level, from an engineering perspective, given our limited dioxin/furan
data base for lightweight aggregate kilns. (We noted that if this were
a large data set, we would have identified the floor emission level
simply as the highest test condition average.) Due to variability among
the runs of the test condition with the highest condition average and
because a floor level of 4.1 ng TEQ/dscm is 40 percent higher than the
highest test condition average of 2.9 ng TEQ/dscm lightweight aggregate
kilns using floor control will be able to meet routinely a floor
emission level of 4.1 ng TEQ/dscm.
We maintain that the floor methodology discussed in the May 1997
NODA is appropriate and we adopt this approach in today's rule. In that
NODA we identified two technologies for control of dioxin/furan
emissions from lightweight aggregate kilns. The first technology
controls dioxin/furans by quenching kiln gas temperatures at the exit
of the kiln so that gas temperatures at the inlet to the particulate
matter control device are below the temperature range of optimum
dioxin/furan formation. The other technology is activated carbon
injected into the kiln exhaust gas. Because activated carbon injection
is not currently used by any hazardous waste burning lightweight
aggregate kilns, this technology was evaluated only as part of a
beyond-the-floor analysis.
One commenter opposes our approach specifying a MACT floor control
temperature limitation of 400 deg.F at the particulate matter control
device. Instead, the commenter supports a temperature limitation of
417 deg.F, which is the highest temperature associated with any dioxin/
furan test condition in our data base. Although only two of the three
test conditions for which we have dioxin/furan emissions data operated
the fabric filter at 400 deg.F or lower (the third operated at
417 deg.F), we do have other fabric filter operating temperatures from
kilns performing RCRA compliance testing for other hazardous air
pollutants that document fabric filter operations at 400 deg.F or
lower. From these data, we conclude that lightweight aggregate kilns
can operate the fabric filter at temperatures of 400 deg.F or lower.
Thus, identifying floor control at a temperature limitation of
400 deg.F ensures that all lightweight aggregate kilns will be
operating consistent with sound operational practices for controlling
dioxin/furan emissions.
As discussed in the May 1997 NODA, specifying a temperature
limitation of 400 deg.F or lower is appropriate for floor control
because, from an engineering perspective, it is within the range of
reasonable values that could have been selected considering that: (1)
The optimum temperature window for surface-catalyzed dioxin/furan
formation is approximately 450-750 deg.F; and (2) temperature levels
below 350 deg.F can cause dew point condensation problems resulting in
particulate matter control device corrosion. Further, lightweight
aggregate kilns can operate at air pollution control device
temperatures between 350 to 400 deg.F. In
[[Page 52892]]
fact, all lightweight aggregate kilns use (or have available) fabric
filter ``tempering'' air dilution and water quench for cooling kiln
exit gases prior to the fabric filter (some kilns also augment this
with uninsulated duct radiation cooling). Thus, the capability of
operating fabric filters at temperatures lower than 400 deg.F currently
exists and is practical. See the technical support document for further
discussion.165
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\165\ USEPA, ``Final Technical Support document for HWC MACT
Standards, Volume III: Selection of MACT Standards and
Technologies,'' July 1999.
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In summary, today's floor emission level for dioxin/furan emissions
for existing lightweight kilns is 0.20 ng TEQ/dscm or 4.1 ng TEQ/dscm
and control of temperature at the inlet to the fabric filter not to
exceed 400 deg.F. We estimate that all lightweight aggregate kiln
sources currently are meeting the floor level.
b. What Are Our Beyond-the-Floor Considerations for Existing
Sources? We considered in the April 1996 proposal a beyond-the-floor
standard of 0.20 ng TEQ/dscm based on injection of activated carbon at
a flue gas temperature of less than 400 deg.F. (61 FR at 17403.) In the
May 1997 NODA, we considered a beyond-the-floor standard of 0.20 ng
TEQ/dscm standard based on rapidly quenching combustion gases at the
exit of the kiln to 400 deg.F, and insulating the duct-work between the
kiln exit and the fabric filter to maintain gas temperatures high
enough to avoid dew point problems. (62 FR at 24232.)
One commenter, however, disagrees that there is adequate evidence
(test data) supporting rapid quench of kiln exit gases to less than
400 deg.F can achieve a level of 0.20 ng TEQ/dscm. Based on these NODA
comments and upon closer analysis of all available data, we find that a
level of 0.20 ng TEQ/dscm has not been clearly demonstrated for
lightweight aggregate kilns with rapid quench less than 400 deg.F prior
to the particulate matter control device. The data show that some
lightweight aggregate kilns can achieve a level of 0.20 TEQ ng/dscm
with rapid quench. In addition, one commenter, who operates two
lightweight aggregate kilns with heat exchangers that cool the flue gas
to a temperature of approximately 400 deg.F at the fabric filter,
stated that they achieve dioxin/furan emissions slightly below 0.20 ng
TEQ/dscm. However, because of the small dioxin/furan data base we are
concerned that these limited data may not show the full range of
emissions. Due to the similarity of dioxin/furan control among cement
kilns and lightweight aggregate kilns, we looked to the cement kiln
data to complement our limited lightweight aggregate kiln dataset. As
discussed earlier, cement kilns are able to control dioxin/furans to
0.40 ng TEQ/dscm with temperature control. Since we do not expect a
lightweight aggregate kiln to achieve lower dioxin/furan emissions than
a cement kiln with rapid quench, we agree with these commenters and
conclude that lightweight aggregate kilns can control dioxin/furans to
0.40 ng TEQ/dscm with rapid quench of kiln exit gases to less than
400 deg.F.
Thus, for the final rule, we considered two beyond-the-floor
levels: (1) Either 0.20 ng TEQ/dscm; or 0.40 ng TEQ/dscm and rapid
quench of the kiln exhaust gas to a temperature less than 400 deg.F;
and (2) a level of 0.20 ng TEQ/dscm based on activated carbon
injection.
The first option is a beyond-the-floor standard of either 0.20 ng
TEQ/dscm, or 0.40 ng TEQ/dscm and rapid quench of the kiln exhaust gas
to less than 400 deg.F. The national incremental annualized compliance
cost for lightweight aggregate kilns to meet this beyond-the-floor
level rather than comply with the floor controls would be approximately
$50,000 for the entire hazardous waste burning lightweight aggregate
kiln industry, and would provide an incremental reduction in dioxin/
furan emissions beyond the MACT floor controls of nearly 2 g TEQ/yr.
Based on these costs of approximately $25 thousand per additional g
of dioxin/furan removed and on the significant reduction in dioxin/
furan emissions achieved, we have determined that this dioxin/furan
beyond-the-floor option for lightweight aggregate kilns is justified,
especially given our special concern about dioxin/furans. Dioxin/furans
are some of the most toxic compounds known due to their bioaccumulation
potential and wide range of health effects, including carcinogenesis,
at exceedingly low doses. Exposure via indirect pathways is a chief
reason that Congress singled out dioxin/furans for priority MACT
control in section 112(c)(6) of the CAA. See S. Rep. No. 128, 101st
Cong. 1st Sess. at 154-155.
We also evaluated, but rejected, activated carbon injection as a
beyond-the-floor option. Carbon injection is routinely effective at
removing 99 percent of dioxin/furans at numerous municipal waste
combustor and medical waste combustor applications and one hazardous
waste incinerator application. However, no hazardous waste burning
lightweight aggregate kiln currently uses activated carbon injection
for dioxin/furan removal. We believe that it is conservative to assume
that only 95 percent is achievable given potential uncertainties in its
application to lightweight aggregate kilns. In addition, we assumed for
cost-effectiveness calculations that lightweight aggregate kilns
needing activated carbon injection would install the activated carbon
injection system after the existing fabric filter device and add a new
smaller fabric filter to remove the injected carbon with the absorbed
dioxin/furans and mercury. This costing approach addresses commenter's
concerns that injected carbon may interfere with current dust recycling
practices.
The national incremental annualized compliance cost for lightweight
aggregate kilns to meet a beyond-the-floor level based on activated
carbon injection rather than comply with the floor controls would be
approximately $1.2 million for the entire hazardous waste burning
lightweight aggregate kiln industry. This would provide an incremental
reduction in dioxin/furan emissions beyond the MACT floor controls of
2.2 g TEQ/yr, or 90 percent. Based on these costs of approximately
$0.53 million per additional g of dioxin/furan removed and the small
incremental dioxin/furan emissions reduction beyond the dioxin/furan
beyond-the-floor option discussed above (2.0 g TEQ/yr versus 2.2 g TEQ/
yr), we have determined that this second beyond-the-floor option for
lightweight aggregate kilns is not justified. Therefore, we are not
promulgating a beyond-the-floor standard of 0.20 ng TEQ/dscm for
lightweight aggregate kilns based on activated carbon injection.
Thus, the promulgated dioxin/furan standard for existing
lightweight aggregate kilns is a beyond-the-floor standard of 0.20 ng
TEQ/dscm; or 0.40 ng TEQ/dscm and rapid quench to a temperature not to
exceed 400 deg.F based on rapid quench of flue gas at the exit of the
kiln.
c. What Is the MACT Floor for New Sources? In the April 1996
proposal, the floor analysis for new lightweight aggregate kilns was
the same as for existing kilns, and the proposed standard was the same.
The proposed floor emission level was 0.20 ng TEQ/dscm, or temperature
at the inlet to the particulate matter control device not to exceed
418 deg.F. (61 FR at 17408.) In the May 1997 NODA, we used an
alternative data analysis method to identify floor control and the
floor emission level. As done for existing sources, floor control for
new sources was defined as temperature control at the inlet to the
particulate matter control device to less than 400 deg.F. That
[[Page 52893]]
analysis resulted in a floor emission level of 0.20 ng TEQ/dscm, or 4.1
ng TEQ/dscm and temperature at the inlet to the fabric filter not to
exceed 400 deg.F. Our engineering evaluation indicated that the best
controlled source is one that is controlling temperature control at the
inlet to the fabric filter at 400 deg.F. (62 FR at 24232.) We continue
to believe that the floor methodology discussed in the May 1997 NODA is
appropriate for new sources and we adopt this approach in the final
rule. The floor level for new lightweight aggregate kilns is 0.20 ng
TEQ/dscm, or 4.1 ng TEQ/dscm and temperature at the inlet to the
particulate matter control device not to exceed 400 deg.F.
d. What Are Our Beyond-the-Floor Considerations for New Sources? In
the April 1996 proposal, we proposed activated carbon injection as
beyond-the-floor control and a beyond-the-floor standard of 0.20 ng
TEQ/dscm. (61 FR at 17408.) In the May 1997 NODA, we identified a
beyond-the-floor standard of 0.20 ng TEQ/dscm based on rapid quench of
kiln gas to less than 400 deg.F combined with duct insulation or
activated carbon injection operated at less than 400 deg.F. (62 FR at
24232.) These beyond-the-floor considerations are identical to those
discussed above for existing sources.
The beyond-the-floor standard identified for existing sources
continues to be appropriate for new sources for the same reasons. Thus,
the promulgated dioxin/furan standard for new lightweight aggregate
kilns is the same as the standard for existing standards, i.e., 0.20 ng
TEQ/dscm or 0.40 ng TEQ/dscm and rapid quench of the kiln exhaust gas
to less than 400 deg.F.
3. What Are the Mercury Standards?
In the final rule, we establish a standard for existing and new
lightweight aggregate kilns that limits mercury emissions to 47 and 33
g/dscm, respectively. The rationale for adopting these
standards is discussed below.
a. What Is the MACT Floor for Existing Sources? All lightweight
aggregate kilns use fabric filters, and one source uses a venturi
scrubber in addition to a fabric filter. However, since mercury is
generally in the vapor form in and downstream of the combustion
chamber, including in the air pollution control device, fabric filters
alone do not achieve significant mercury control. Mercury emissions
from lightweight aggregate kilns are currently controlled under
existing regulations through limits on the maximum feedrate of mercury
in total feedstreams (e.g., hazardous waste, raw materials). Thus, MACT
floor control is based on limiting the feedrate of mercury in hazardous
waste.
In the April 1996 proposal, we identified floor control as
hazardous waste feedrate control not to exceed a feedrate level of 17
g/dscm, expressed as a maximum theoretical emissions
concentration, and proposed a floor emission level of 72 g/
dscm based on an analysis of data from all lightweight aggregate kilns
with a hazardous waste feedrate of mercury of this level or lower. (61
FR at 17404.) In the May 1997 NODA, we conducted a breakpoint analysis
on ranked mercury emissions data and established the floor emission
level equal to the test condition average of the breakpoint source. (62
FR at 24232.) The breakpoint analysis was intended to reflect an
engineering-based evaluation of the data whereby the few lightweight
aggregate kilns spiking extra mercury during testing procedures did not
drive the floor emission level to levels higher than the preponderance
of the emission data. We reasoned that sources with emissions higher
than the breakpoint source were not controlling the hazardous waste
feedrate of mercury to levels representative of MACT. The May 1997 NODA
analysis resulted in a MACT floor level of 47 g/dscm.
One commenter states that the use of mercury stack gas measurements
from RCRA compliance test reports is inappropriate for setting the MACT
floor since they are based on feeding normal wastes. With the exception
of one source, no mercury spiking was done during the RCRA compliance
testing because lightweight aggregate kilns complied with Tier I levels
allowable in the Boiler and Industrial Furnace rule. The commenter
notes that the Tier I allowable levels are above, by orders of
magnitude, the total mercury fed into lightweight aggregate kilns.
Thus, to set the mercury MACT floor, the commenter states that we need
to consider the potential range of mercury levels in the hazardous
waste and raw materials, which may not represented by the RCRA
compliance stack gas measurements.
We recognize that stack gas tests generating mercury emissions data
were conducted with normal unspiked waste streams containing normal
levels of mercury in hazardous waste. However, we concluded that it is
appropriate in this particular circumstance to use unspiked data to
define a MACT floor. See discussion in Part Four, Section V.D.1. It
would hardly reflect MACT to base the floor emission level on a
feedrate of mercury greater than that which actually occurs in
hazardous waste fuels burned in these units. Furthermore, the final
rule standard is projected to be achievable by lightweight aggregate
kilns for the vast majority of the wastes they are currently handling.
The standard would allow lightweight aggregate kilns to burn wastes
with about 0.5 ppmw mercury, without use of add-on mercury control
techniques such as carbon injection. Data provided by a commenter
indicates that approximately 90% of the waste streams lightweight
aggregate kilns currently burn do not contain mercury levels at 2 ppmw.
Further, the commenter indicates that these wastes are typically less
than 0.02 ppmw mercury when more refined and costly analysis techniques
are used. Thus, the standard is consistent with the current practice of
lightweight aggregate kilns burning low-mercury waste.
We received comments from the lightweight aggregate kiln industry
expressing concern with the stringency of the mercury standard. These
commenters oppose a mercury standard of 47 g/dscm, in part,
because of the difficulty and increased cost of demonstrating
compliance with day-to-day mercury feedrate limits. One potential
problem pertains to raw material mercury detection limits. The
commenter states that mercury is generally not measured in the raw
material at detectable levels at their facilities. The commenter points
out that if a kiln assumes mercury is present in the raw material at
the detection limit, the resulting calculated uncontrolled mercury
emission concentration could exceed, or be a significant percentage of,
the mercury emission standard. This may prevent a kiln from complying
with the mercury emission standard even though MACT control is used.
Further, the commenter anticipates that more frequent analysis,
additional laboratory equipment and staff, and improved testing and
analysis procedures will be required to show compliance with a standard
of 47 g/dscm. The commenter states that the costs of
compliance will increase significantly at each facility to address this
nondetect issue.
Four provisions in the final rule offer flexibility in complying
with the mercury standard. For example, one provision allows sources to
petition for an alternative mercury standard that only requires
compliance with a hazardous waste mercury feedrate limitation, provided
that mercury not been present historically in the raw material at
detectable levels. This approach ensures that kilns using MACT controls
can achieve the mercury standard. The details of this provision are
discussed in Part Five, Section
[[Page 52894]]
X.A.2. Another provision allows kilns a waiver of performance testing
requirements when the source feeds low levels of mercury. Under this
provision, a kiln qualifies for a waiver of the performance testing
requirements for mercury if all mercury from all feedstreams fed to the
combustion unit does not exceed the mercury emission standard. For
kilns using this waiver, we allow kilns to assume mercury in the raw
material is present at one-half the detection limit whenever the raw
materials feedstream analysis determines that mercury is not present at
detectable levels. The details of this provision are presented in Part
Five, Section X.B. For a discussion of the other two methods that can
be used to comply with the mercury emission standard, see Part Five,
Section VII.B.6.
For today's rule we use a revised engineering evaluation and data
analysis method to establish the MACT floor emission level for mercury.
The approach used to establish MACT floors for the three metal
hazardous air pollutant groups and hydrochloric acid/chlorine gas is
the aggregate feedrate approach. Using this approach, the resulting
mercury floor emission level is 47 g/dscm.
We estimate that approximately 75 percent of lightweight aggregate
kiln sources currently are meeting the floor emission level. The
national annualized compliance cost for lightweight aggregate kilns to
reduce mercury emissions to comply with the floor emission level is
$0.7 million for the entire hazardous waste burning lightweight
aggregate kiln industry, and will reduce mercury emissions by
approximately 0.03 Mg/yr or 47 percent from current baseline emissions.
b. What Are Our Beyond-the-Floor Considerations for Existing
Sources? In the April 1996 NPRM, we considered a beyond-the-floor
standard based on flue gas temperature reduction to 400 deg.F or less
followed by activated carbon injection, but determined that a beyond-
the-floor level would not be cost-effective and therefore warranted.
(61 FR at 17404.) In the May 1997 NODA, we considered a beyond-the-
floor standard of 15 g/dscm based on an activated carbon
injection. However, we indicated in the NODA that a beyond-the-floor
standard would not likely be justified given the high cost of treatment
and the relatively small amount of mercury removed from air emissions.
(62 FR at 24232.)
In developing the final rule, we identified three techniques for
control of mercury as a basis to evaluate a beyond-the-floor standard:
(1) Activated carbon injection; (2) limiting the feed of mercury in the
hazardous waste; and (3) limiting the feed of mercury in the raw
materials. The results of each analysis are discussed below.
Activated Carbon Injection. To investigate this beyond-the-floor
control option, we applied a carbon injection capture efficiency of 80
percent to the floor emission level of 47 g/dscm. The
resulting beyond-the-floor emission level is 10 g/dscm.
The national incremental annualized compliance cost for lightweight
aggregate kilns to meet this beyond-the-floor level rather than comply
with the floor controls would be approximately $0.6 million for the
entire hazardous waste burning lightweight aggregate kiln industry and
would provide an incremental reduction in mercury emissions beyond the
MACT floor controls of 0.02 Mg/yr. Based on these costs of
approximately $34 million per additional Mg of mercury removed and the
small emissions reductions that would be realized, we conclude that
this mercury beyond-the-floor option for hazardous waste burning
lightweight aggregate kilns is not acceptably cost-effective nor
otherwise justified. Therefore, we do not adopt this beyond-the-floor
standard.
Limiting the Feedrate of Mercury in Hazardous Waste. We also
considered, but rejected, a beyond-the-floor emission level based on
limiting the feed of mercury in the hazardous waste. This mercury
beyond-the-floor option for lightweight aggregate kilns is not
warranted because data submitted by commenters indicate that
approximately 90% of the hazardous waste burned by lightweight
aggregate kilns contains mercury at levels below method detection
limits. We conclude from these data that there are little additional
mercury reductions possible by reducing the feed of mercury in the
hazardous waste. Therefore, we are not adopting a beyond-the-floor
emission level because it will not be cost-effective due to the
relatively small amount of mercury removed from air emissions and
likely problems with method detection limitations.
Limiting the Feedrate of Mercury in Raw Materials. A source can
achieve a reduction in mercury emissions by substituting a feed
material containing lower levels of mercury for a primary raw material
higher mercury levels. This beyond-the-floor option appears to be less
cost effective compared to either of the options evaluated above.
Because lightweight aggregate kilns are sited proximate to primary raw
material supply and transporting large quantities of an alternative
source of raw material(s) is expected to be cost prohibitive.
Therefore, we do not adopt this mercury beyond-the-floor standard.
Thus, the promulgated mercury standard for existing hazardous waste
burning lightweight aggregate kilns is the floor emission level of 47
g/dscm.
c. What Is the MACT Floor for New Sources? In the April 1996
proposal, we identified floor control for new sources as hazardous
waste feedrate control of mercury not to exceed a feedrate level of 17
g/dscm expressed as a maximum theoretical emissions
concentration. We proposed a floor emission level of 72 g/
dscm. (61 FR at 17408.) In May 1997 NODA, we conducted a breakpoint
analysis on ranked mercury emissions data from sources utilizing the
MACT floor technology and established the floor emission level as the
test condition average of the breakpoint source. The breakpoint
analysis was intended to reflect an engineering-based evaluation of the
data so that the one lightweight aggregate kiln spiking extra mercury
during testing procedures did not drive the floor emission level to
levels higher than the preponderance of the emissions data. This
analysis resulted in a MACT floor level of 47 g/dscm. (62 FR
at 24233.)
For the final rule, we identify floor control for new lightweight
aggregate kilns as feed control of mercury in the hazardous waste,
based on the single source with the best aggregate feedrate of mercury
in hazardous waste. Using the aggregate feedrate approach to establish
this floor level of control and corresponding floor emission level, we
identify a MACT floor emission level of 33 g/dscm for new
lightweight aggregate kilns.
d. What Are Our Beyond-the-Floor Considerations for New Sources? In
both the proposal and the NODA, we considered a beyond-the-floor
standard for new sources based on activated carbon injection, but
determined that it would not be cost-effective to adopt the beyond-the-
floor standard given the high cost of treatment and the relatively
small amount of mercury removed from air emissions. (61 FR at 17408 and
62 FR at 24233.)
In the final rule, we identified three techniques for control of
mercury as a basis to evaluate a beyond-the-floor standard: (1)
Activated carbon injection; and (2) limiting the feed of mercury in the
hazardous waste. The results of each analysis are discussed below.
Activated Carbon Injection. As discussed above, we conclude that
flue gas temperature reduction to 400 deg.F followed by activated
carbon injection to remove mercury is an appropriate beyond-the-floor
control option for improved mercury control at
[[Page 52895]]
lightweight aggregate kilns. The control of flue gas temperature is
necessary to ensure good collection efficiency. Based on the MACT floor
emission level of 33 g/dscm and assuming a carbon injection
capture efficiency of 80 percent, we identified a beyond-the-floor
emission level of 7 g/dscm. As discussed above for existing
sources, we do not believe that a beyond-the-floor standard of 7
g/dscm is warranted for new lightweight aggregate kilns due to
the high cost of treatment and relatively small amount of mercury
removed from air emissions. The incremental annualized compliance cost
for one new lightweight aggregate kiln to meet this beyond-the-floor
level, rather than comply with floor controls, would be approximately
$0.46 million and would provide an incremental reduction in mercury
emissions beyond the MACT floor controls of approximately 0.008 Mg/yr.
Based on these costs of approximately $58 million per additional Mg of
mercury removed, a beyond-the-floor standard of 7 g/dscm is
not warranted due to the high cost of compliance and relatively small
mercury emissions reductions. Notwithstanding our goal of reducing the
loading to the environment by bioaccumulative pollutants such as
mercury whenever possible, these costs are not justified.
Limiting the Feedrate of Mercury in Hazardous Waste. As discussed
above for existing sources, we conclude that a beyond-the-floor based
on limiting the feed of mercury in the hazardous waste is not
justified. Considering that the floor emission level for new
lightweight aggregate kilns is approximately one third lower than the
floor emission level for existing kilns (33 versus 47 g/dscm),
we again conclude that a mercury beyond-the-floor standard is not
warranted because emission reductions of mercury would be less than
existing sources at comparable costs. Thus, the cost-effectiveness is
higher for new kilns than for existing kilns. Further, achieving
substantial additional mercury reductions by further controls on
hazardous waste feedrate may be problematic because the mercury
contribution from raw materials and coal represents an even larger
proportion of the total mercury fed to the kiln. Therefore, we do not
adopt a mercury beyond-the-floor standard based on limiting feed of
mercury in hazardous waste for new sources.
Thus, the promulgated mercury standard for new hazardous waste
burning lightweight aggregate kilns is the floor emission level of 33
g/dscm.
4. What Are the Particulate Matter Standards?
We establish standards for both existing and new lightweight
aggregate kilns that limit particulate matter emissions to 57 mg/dscm.
The particulate matter standard is a surrogate control for the metals
antimony, cobalt, manganese, nickel, and selenium. We refer to these
five metals as ``nonenumerated metals'' because standards specific to
each metal have not been established. The rationale for adopting these
standards is discussed below.
a. What Is the MACT Floor for Existing Sources? In the April 1996
NPRM, we defined floor control based upon the performance of a fabric
filter with an air-to-cloth ratio of 2.8 acfm/ft2. The MACT
floor was 110 mg/dscm (0.049 gr/dscf). (61 FR at 17403.) In the May
1997 NODA, we defined the technology basis as a fabric filter for a
MACT floor, but did not characterize the design and operation
characteristics of the particulate matter control equipment, air-to-
cloth ratio of a fabric filter, because we had limited information on
these parameters. (62 FR at 24233.) Instead, for each particulate
matter test condition, we evaluated the corresponding semivolatile
metal system removal efficiency and screened out sources with
relatively poor system removal efficiencies as a means to identify and
eliminate from consideration those sources not using MACT floor
control. Our reevaluation of the lightweight aggregate kiln particulate
matter data resulted in a MACT floor of 50 mg/dscm (0.022 gr/dscf).
Some commenters state that a floor emission level of 50 mg/dscm
(0.022 gr/dscf) is too high and a particulate matter standard of 23 mg/
dscm (0.010 gr/dscf) is more appropriate because it is consistent with
the level of performance achieved by incinerators using fabric filters.
Even though we agree that well designed and properly operated fabric
filters in use at all lightweight aggregate kilns can achieve low
levels, we are concerned that an emission level of 23 mg/dscm would not
be appropriate given the high inlet grain loading inherent with the
lightweight aggregate manufacturing process, typically much higher than
the particulate loading to incinerators.
Commenters also express concern that the Agency identified
separate, different MACT pools and associated MACT controls for
particulate matter, semivolatile metals, and low volatile metals, even
though all three are controlled, at least in part, by the particulate
matter control device. These commenters stated that our approach is
likely to result in three different design specifications. We agree
with these commenters and, in the final rule, the same initial MACT
pool is used to establish the floor levels for particulate matter,
semivolatile metals, and low volatile metals. See discussion in Part
Four, Section V.
For the final rule, we conclude that the general floor methodology
discussed in the May 1997 NODA is appropriate. MACT control for
particulate matter is based on the performance of fabric filters. Since
we lack data to fully characterize control equipment from all sources
and we lack information on the relationship between the design
parameters and the system performance, we evaluated both low and
semivolatile metal system removal efficiencies associated with the
source's particulate matter emissions to identify those sources not
using MACT floor control. Our data show that all lightweight aggregate
kilns are achieving greater than 99 percent system removal efficiency
for both low and semivolatile metals, with some attaining 99.99 percent
removal. Since we found no sources with system removal efficiencies
indicative of poor performance, we conclude that all lightweight
aggregate kilns are using MACT controls and the floor emission limit is
identified as 57 mg/dscm (0.025 gr/dscf).
The performance level of 57 mg/dscm is generally consistent with
that expected from well designed and operated fabric filters, and that
achieved by other similar types of combustion sources operating with
high inlet grain loadings. We have particulate matter data from all
lightweight aggregate kiln sources, and multiple test conditions,
conducted at 3 year intervals, are available for many of the sources.
We conclude that the number of test conditions available adequately
covers the range of variability of well operated and designed fabric
filters.166
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\166\ USEPA, ``Final Technical Support Document for HWC MACT
Standards, Volume III: Selection of MACT Standards and
Technologies,'' July 1999.
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We considered, but rejected, basing the particulate matter floor
for lightweight aggregate kilns on the New Source Performance Standard.
The New Source Performance Standard limits particulate matter emissions
to 92 mg/dscm (0.040 gr/dscf), uncorrected for oxygen. (See 40 CFR
60.730, Standards of Performance for Calciners and Dryers in Mineral
Industries.) We rejected the New Source Performance Standard as the
basis for the floor emission level
[[Page 52896]]
because our MACT analysis of data from existing sources indicates that
a particulate matter floor level lower than the New Source Performance
Standard is currently being achieved by existing hazardous waste
burning lightweight aggregate kilns. Further, all available emission
data for hazardous waste burning lightweight aggregate kilns are well
below the New Source Performance Standard particulate matter standard.
Thus, the particulate matter floor emission level is 57 mg/dscm based
on an analysis of existing emissions data.
We estimate that, based on a design level of 70 percent of the
standard, over 90 percent of lightweight aggregate kiln sources
currently are meeting the floor level. The national annualized
compliance cost for lightweight aggregate kilns to reduce particulate
matter emissions to comply with the floor emission level is $18,000 for
the entire hazardous waste burning lightweight aggregate kiln industry,
and our floor will reduce nonenumerated metals and particulate matter
emissions by 0.01 Mg/yr and 2.7 Mg/yr, respectively, or 7 percent from
current baseline emissions.
b. What Are Our Beyond-the-Floor Considerations for Existing
Sources? In the NPRM, we proposed a beyond-the-floor emission level of
69 mg/dscm (0.030 gr/dscf) and solicited comment on an alternative
beyond-the-floor emission level of 34 mg/dscm (0.015 gr/dscf) based on
improved particulate matter control. (61 FR at 17403.) In the May 1997
NODA, we concluded that a beyond-the-floor standard may not be
warranted given a reduced particulate matter floor level compared to
the proposed floor emission level. (62 FR at 24233.)
In the final rule, we considered a beyond-the-floor level of 34 mg/
dscm for existing lightweight aggregate kilns based on improved
particulate matter control. For analysis purposes, improved particulate
matter control entails the use of higher quality fabric filter bag
material. We then determined the cost of achieving this level of
particulate matter, with corresponding reductions in the nonenumerated
metals for which particulate matter is a surrogate, to determine if
this beyond-the-floor level would be appropriate. The national
incremental annualized compliance cost for lightweight aggregate kilns
to meet this beyond-the-floor level, rather than comply with the floor
controls, would be approximately $110,000 for the entire hazardous
waste burning lightweight aggregate kiln industry and would provide an
incremental reduction in nonenumerated metals emissions nationally
beyond the MACT floor controls of 0.03 Mg/yr. Based on these costs of
approximately $3.7 million per additional Mg of nonenumerated metals
emissions removed, we conclude that this beyond-the-floor option for
lightweight aggregate kilns is not acceptably cost-effective nor
otherwise justified. Therefore, we do not adopt this beyond-the-floor
standard. Thus, the promulgated particulate matter standard for
existing hazardous waste burning lightweight aggregate kilns is the
floor emission level of 57 mg/dscm.
c. What Is the MACT Floor for New Sources? In the April 1996
proposal, we defined floor control for new sources based on the level
of performance of a fabric filter with an air-to-cloth ratio of 1.5
acfm/ft2. The MACT floor emission level was 120 mg/dscm (0.054 gr/
dscf). (61 FR at 17408.) In the May 1997 NODA, MACT control was defined
as a well-designed and properly operated fabric filter, and the floor
emission level for new lightweight aggregate kilns was 50 mg/dscm
(0.022 gr/dscf). (62 FR at 24233.)
All lightweight aggregate kilns use fabric filters to control
particulate matter. As discussed earlier, we have limited information
on the design and operation characteristics of existing control
equipment currently used by lightweight aggregate kilns. As a result,
we are unable to identify a specific technology that can consistently
achieve lower emission levels than the controls used by lightweight
aggregate kilns achieving the MACT floor level for existing sources.
Lightweight aggregate kilns achieve the floor emission level with well-
designed and properly operated fabric filters. Thus, floor control for
new kilns is likewise a well-designed and properly operated fabric
filter. Therefore, as discussed for existing sources, the MACT floor
level for new lightweight aggregate kilns is 57 mg/dscm (0.025 gr/
dscf).
d. What Are Our Beyond-the-Floor Considerations for New Sources? In
the April 1996 NPRM, we proposed a beyond-the-floor standard of 69 mg/
dscm (0.030 gr/dscf) based on improved particulate matter control,
which was consistent with existing sources. (61 FR at 17408.) In the
May 1997 NODA, we concluded, as we did for existing sources, that a
beyond-the-floor level for particulate matter may not be warranted due
to the high costs of control and relatively small amount of particulate
matter removed from air emissions. (62 FR at 24233.)
As discussed for existing sources, we considered a beyond-the-floor
level of 34 mg/dscm for new lightweight aggregate kilns based on
improved particulate matter control. For analysis purposes, improved
particulate matter control entails the use of higher quality fabric
filter bag material. We then determined the cost of achieving this
level of particulate matter, with corresponding reductions in the
nonenumerated metals for which particulate matter is a surrogate, to
determine if this beyond-the-floor level would be appropriate. The
incremental annualized compliance cost for one new lightweight
aggregate kiln to meet this beyond-the-floor level, rather than comply
with floor controls, would be approximately $38 thousand and would
provide an incremental reduction in nonenumerated metals emissions of
approximately 0.012 Mg/yr.167 Based on these costs of
approximately $3.1 million per additional Mg of nonenumerated metals
removed, we conclude that a beyond-the-floor standard of 34 mg/dscm is
not justified due to the high cost of compliance and relatively small
nonenumerated metals emission reductions. Further, a standard of 57 mg/
dscm would adequately control the unregulated hazardous air pollutant
metals for which it is being used as a surrogate. Thus, the particulate
matter standard for new lightweight aggregate kilns is the floor level
of 57 mg/dscm.
---------------------------------------------------------------------------
\167\ Based on the data available, the average emissions in sum
of the five nonenumerated metal from lightweight aggregate kilns
using MACT particulate matter control is approximately 83
g/dscm. To estimate emission reductions of the
nonenumerated metals, we assume a linear relationship between a
reduction in particulate matter and these metals.
---------------------------------------------------------------------------
5. What Are the Semivolatile Metals Standards?
In the final rule, we establish a standard for existing and new
lightweight aggregate kilns that limits semivolatile metal emissions to
250 and 43 g/dscm, respectively. The rationale for adopting
these standards is discussed below.
a. What Is the MACT Floor for Existing Sources? All lightweight
aggregate kilns use a combination of particulate matter control, i.e.,
a fabric filter, and hazardous waste feedrate to control emissions of
semivolatile metals. Current RCRA regulations establish limits on the
maximum feedrate of lead and cadmium in all feedstreams. Thus,
hazardous waste feedrate control is part of MACT floor control.
In the April 1996 proposal, we defined floor control as either (1)
a fabric filter with an air-to-cloth ratio of 1.5 acfm/ft 2
and a hazardous waste feedrate level of 270,000 g/dscm,
[[Page 52897]]
expressed as a maximum theoretical emissions concentration; or (2) a
combination of a fabric filter and venturi scrubber with an air-to-
cloth ratio of 4.2 acfm/ft 2 and a hazardous waste feedrate
level of 54,000 g/dscm. The proposed floor emission level was
12 g/dscm. (61 FR at 17405.) In the May 1997 NODA, we
discussed a floor methodology where we used a breakpoint analysis to
identify sources that were not using floor control with respect either
to semivolatile metals hazardous waste feedrate or emissions control.
Under this approach, we ranked semivolatile metal emissions data from
sources that were achieving the particulate matter floor level of 50
mg/dscm or better. We identified the floor level as the test condition
average associated with the breakpoint source. Thus, sources with
atypically high emissions because of high semivolatile feedrate levels
or poor semivolatile metals control were screened from the pool of
sources used to define the floor emission level. Based on this
analysis, we identified a floor emission level of 76 g/dscm.
(62 FR at 24234.)
We received few public comments in response to the proposal and May
1997 NODA concerning the lightweight aggregate kiln semivolatile metals
floor emission level. We did receive comments on the application of
techniques to identify breakpoints in the arrayed emissions data. This
issue and our response to it are discussed in the floor methodology
section in Part Four, Section V. We also received comments that our
semivolatile metals analysis in the proposal and May 1997 NODA included
several data base inaccuracies that, when corrected, would result in a
higher floor level. We agree with the commenters and we revised the
data base as necessary for the final rule analysis.
In the final rule, in general response to these comments, we use a
revised engineering evaluation and data analysis method to establish
the floor emission level for semivolatile metals. We use the aggregate
feedrate approach in conjunction with floor control for particulate
matter of 57 mg/dscm to identify a semivolatile metal floor emission
level of 1,700 g/dscm. We estimate that all lightweight
aggregate kiln sources currently are meeting the floor level.
b. What Are Our Beyond-the-Floor Considerations for Existing
Sources? In the April 1996 NPRM, we considered a beyond-the-floor
emission level for semivolatile metals based on improved particulate
matter control. We concluded that a beyond-the-floor emission level
would not be cost-effective given that the proposed semivolatile metal
floor level of 12 g/dscm alone would result in an estimated 97
percent reduction in semivolatile metal emissions. (61 FR at 17405.) In
the May 1997 NODA, we considered a beyond-the-floor emission level
based on improved particulate matter control, but indicated that such a
standard was not likely to be cost-effective due to the high costs of
control. (62 FR at 24234.)
In developing the final rule, we identified three techniques for
control of semivolatile metals as a basis to evaluate a beyond-the-
floor standard: (1) Limiting the feed of semivolatile metals in the
hazardous waste; (2) improved particulate matter control; and (3)
limiting the feed of semivolatile metals in the raw materials. The
results of each analysis are discussed below.
Limiting the Feedrate of Semivolatile Metals in Hazardous Waste.
Under this option, as with cement kilns, we selected for evaluation a
beyond-the-floor emission level of 240 g/dscm to evaluate from
among the range of possible levels that reflect improved feedrate
control of semivolatile metals in hazardous waste. This emission level
represents a significant increment of emission reduction from the floor
level of 1700 g/dscm, it is within the range of levels that
are likely to be reasonably achievable using feedrate control, and it
is generally consistent with the incinerator and cement kiln standards,
thereby advancing a policy objective of essentially common standards
among combustors of hazardous waste.
In performing an analysis of the 240 g/dscm beyond-the-
floor limit, we found that additional reductions beyond 250 g/
dscm represent a significant reduction in cost-effectiveness of
incremental beyond-the-floor levels. A beyond-the-floor standard of 250
g/dscm achieves the same goals as a beyond-the-floor standard
of 240 g/dscm in a more cost-effective manner. The national
incremental annualized compliance cost for the lightweight aggregate
kilns to meet this 250 g/dscm beyond-the-floor level, rather
than comply with the floor controls, would be approximately $88,000 and
would provide an incremental reduction beyond emissions at the MACT
floor in semivolatile metal emissions of an additional 0.17 Mg/yr. The
cost-effectiveness of this emission level is approximately $530,000 per
additional Mg of semivolatile metal removed.
We conclude that additional control of the feedrate of semivolatile
metals in hazardous waste to achieve an emission level of 250
g/dscm is warranted because this standard would reduce lead
and cadmium emissions, which are particularly toxic hazardous air
pollutants. In addition, Solite Corporation, which operates the
majority of the hazardous waste burning lightweight aggregate kilns,
stated in their public comments that a standard of 213 g/dscm
is achievable and adequately reflects the variability of lead and
cadmium in raw material for their kilns. Further, the vast majority of
the lead and cadmium fed to the lightweight aggregate kiln is from the
hazardous waste,168 not from the raw material or coal. We
are willing to accept a more marginal cost-effectiveness for sources
voluntarily burning hazardous waste in lieu of other fuels to ensure
that sources are using best controls.
---------------------------------------------------------------------------
\168\ USEPA, ``Final Technical Support Document for HWC MACT
Standards, Volume III: Selection of MACT Standards and
Technologies'', July 1999.
---------------------------------------------------------------------------
Moreover, this beyond-the-floor semivolatile metal standard better
supports our Children's Health Initiative in that lead emissions, which
are of highest significance to children's health, will be reduced by
another 60 percent from today's baseline. We are committed to reducing
lead emissions wherever and whenever possible. Finally, we note that
this beyond-the-floor standard is also consistent with European Union
standards for hazardous waste incinerators of approximately 200
g/dscm for lead and cadmium combined. Therefore, we are
adopting today a beyond-the-floor standard of 250 g/dscm for
existing lightweight aggregate kilns.
Improved Particulate Matter Control. We also evaluated improved
particulate matter control as another beyond-the-floor control option
for improved semivolatile metals control. We investigated a beyond-the-
floor standard of 250 g/dscm, an emission level consistent
with the preferred option based on limiting the feedrate of
semivolatile metals in hazardous waste. The national incremental
annualized compliance cost for lightweight aggregate kilns to meet this
beyond-the-floor level, rather than comply with the floor controls,
would be approximately $88,000 thousand for all lightweight aggregate
kilns and would provide an incremental reduction in semivolatile metal
emissions beyond the MACT floor controls of 0.17 Mg/yr. Based on these
costs of approximately $530,000 per additional Mg of semivolatile metal
removed, we determined that this beyond-the-floor option may be
warranted. However, as discussed below, the cost-effectiveness for this
beyond-the-floor option is approximately equivalent to the costs
[[Page 52898]]
estimated for a beyond-the-floor option based on limiting the feed of
semivolatile metals in the hazardous waste. We decided to base the
beyond-the-floor standard for semivolatile metals on the feedrate
option to be consistent with the cement kiln approach. Of course light-
weight aggregate kilns are free to choose to improve particulate matter
control in lieu of feedrate controls as their vehicle to achieve
compliance with 250 ug/dscm.
Limiting the Feedrate of Semivolatile Metals in Raw Materials. A
source can achieve a reduction in semivolatile metals emissions by
substituting a feed material containing lower levels of lead and/or
cadmium for a primary raw material higher in lead and/or cadmium
levels. This beyond-the-floor option appears to be less cost effective
compared to either of the options evaluated above because lightweight
aggregate kilns are sited proximate to primary raw material supply.
Transporting large quantities of an alternative source of raw
material(s) is expected to be cost prohibitive. Therefore, we do not
adopt this semivolatile metal beyond-the-floor standard.
Thus, the promulgated semivolatile metals standard for existing
hazardous waste burning lightweight aggregate kilns is a beyond-the-
floor standard of 250 g/dscm based on limiting the feedrate of
semivolatile metals in the hazardous waste.
c. What Is the MACT Floor for New Sources? In the April 1996
proposal, we defined floor control as a fabric filter with an air-to-
cloth ratio of 1.5 acfm/ft2 and a hazardous waste feedrate
level of 270,000 g/dscm, expressed as a maximum theoretical
emissions concentration. The proposed floor emission level was 5.2
g/dscm. (61 FR at 17408.) In the May 1997 NODA, we concluded
that the floor control and emission level for existing sources for
semivolatile metals would also be appropriate for new sources. Floor
control was based on a combination of good particulate matter control
and limiting hazardous waste feedrates of semivolatile metals to
control emissions. We used a breakpoint analysis of the semivolatile
metal emissions data to exclude sources achieving substantially poorer
semivolatile metal control than the majority of sources. The NODA floor
emission level was 76 g/dscm for new sources. (62 FR at
24234.)
In the final rule, as discussed previously, we use a revised
engineering evaluation and data analysis method to establish the floor
emission level for semivolatile metals. We use the aggregate feedrate
approach in conjunction with floor control for particulate matter of 57
mg/dscm to identify a semivolatile metal floor emission level of 43
g/dscm.
d. What Are Our Beyond-the-Floor Considerations for New Sources? In
the April 1996 NPRM and May 1997 NODA, we considered a semivolatile
metal beyond-the-floor emission level for new sources, but determined
that the standard would not be cost-effective because the floor
emission levels already achieved significant reductions in semivolatile
metals emissions. (61 FR at 17408 and 62 FR at 24234.)
For the final rule, we do not adopt a beyond-the-floor emission
level because the MACT floor for new sources is already substantially
lower than the beyond-the-floor emission standard for existing sources.
As a result, a beyond-the-floor standard for new lightweight aggregate
kilns is not warranted due to the high costs of control versus the
minimal emissions reductions that would be achieved. Therefore, we
adopt the semivolatile metal MACT floor standard of 43 g/dscm
for new hazardous waste burning lightweight aggregate kilns.
6. What Are the Low Volatile Metals Standards?
In the final rule, we establish a standard for both existing and
new lightweight aggregate kilns that limits low volatile metal
emissions to 110 g/dscm. The rationale for adopting these
standards is discussed below.
a. What Is the MACT Floor for Existing Sources? In the April 1996
proposal, we defined floor control based on the performance of a fabric
filter with an air-to-cloth ratio of 1.8 acfm/ft2 and a
hazardous waste feedrate level of 46,000 g/dscm, expressed as
a maximum theoretical emissions concentration. The proposed floor
emission level was 340 g/dscm. (61 FR at 17405.) In the May
1997 NODA, we discussed a floor methodology where we used a breakpoint
analysis to identify sources that were not using floor control with
respect either to low volatile metals hazardous waste feedrate or
emissions control. Under this approach, we ranked low volatile metal
emissions data from sources that were achieving the particulate matter
floor level of 50 mg/dscm or better. We identified the floor level as
the test condition average associated with the breakpoint source. Thus,
sources with atypically high emissions because of high low volatile
feedrate levels or poor low volatile metals control were screened from
the pool of sources used to define the floor emission level. Based on
this analysis, we identified a floor emission level of 37 g/
dscm. (62 FR at 24234.)
We received few comments, in response to the April 1996 NPRM and
May 1997 NODA, concerning the low volatile metals floor emission level.
We received comments, however, on several overarching issues including
the appropriateness of considering feedrate control of metals
(including low volatile metals) in hazardous waste as a MACT floor
control technique and the specific procedure of identifying breakpoints
of arrayed emissions data. These issues and our responses to them are
discussed in the floor methodology section in Part Four, Section V.
For today's rule, we use a revised engineering evaluation and data
analysis method to establish the MACT floor level for low volatile
metals. The aggregate feedrate approach in conjunction with MACT
particulate matter control to 57 mg/dscm results in a low volatile
metal floor emission level of 110 g/dscm.
We estimate that over 80 percent of existing lightweight aggregate
kiln sources in our data base meet the floor level. The national
annualized compliance cost for lightweight aggregate kilns to reduce
low volatile metal emissions to comply with the floor emission level is
$52,000 for the entire hazardous waste burning lightweight aggregate
kiln industry, and will reduce low volatile metal emissions by 0.04 Mg/
yr or 40 percent from current baseline emissions.
b. What Are Our Beyond-the-Floor Considerations for Existing
Sources? In the April 1996 NPRM and May 1997 NODA, we considered a
beyond-the-floor standard for low volatile metals based on improved
particulate matter control. However, we concluded that a beyond-the-
floor standard would not be cost-effective due to the high cost of
emissions control and relatively small amount of low volatile metals
removed from air emissions. (61 FR at 17406 and 62 FR at 24235.)
For today's rule, we identified three potential beyond-the-floor
techniques for control of low volatile metals: (1) Improved particulate
matter control; (2) limiting the feed of low volatile metals in the
hazardous waste; and (3) limiting the feed of low volatile metals in
the raw materials. The results of each analysis are discussed below.
Improved Particulate Matter Control. Our judgment is that a beyond-
the-floor standard based on improved particulate matter control would
be less cost-effective that a beyond-the-floor option based on limiting
the feedrate of low
[[Page 52899]]
volatile metals in the hazardous waste. Our data show that lightweight
aggregate kilns are already achieving a 99.9% system removal efficiency
of low volatile metals and some sources are even attaining 99.99%.
Thus, pollution control equipment retrofit costs for improved control
would be significant. Thus, we conclude a beyond-the-floor emission
level for low volatile metals based on improved particulate matter
control for lightweight aggregate kilns is not warranted.
Limiting the Feedrate of Low Volatile Metals in the Hazardous
Waste. We also considered a beyond-the-floor level of 70 g/
dscm based on additional feedrate control of low volatile metals in the
hazardous waste. Our investigation shows that this beyond-the-floor
option would achieve an incremental reduction in low volatile metals of
only 0.01 Mg/yr. Given that this beyond-the-floor level would not
achieve appreciable emissions reductions, significant cost-
effectiveness considerations would likely arise, thus suggesting that
this beyond-the-floor standard is not warranted.
Limiting the Feedrate of Low Volatile Metals in Raw Materials. A
source can achieve a reduction in low volatile metal emissions by
substituting a feed material containing lower levels of these metals
for a primary raw material higher low volatile metal levels. This
beyond-the-floor option appears to be less cost-effective compared to
either of the options evaluated above because lightweight aggregate
kilns are sited proximate to primary raw material supply. Transporting
large quantities of an alternative source of raw material(s) is
expected to be very costly and not cost-effective considering the
limited emissions reductions that would be achieved. Therefore, we do
not adopt this low volatile metals beyond-the-floor standard.
For reasons discussed above, we do not adopt a beyond-the-floor
level for low volatile metals, and establish the emissions standard for
existing hazardous waste burning lightweight aggregate kilns at 110
g/dscm.
c. What Is the MACT Floor for New Sources? At proposal, we defined
floor control based on the performance of a fabric filter with an air-
to-cloth ratio of 1.3 acfm/ft2 a hazardous waste feedrate
level of 37,000 g/dscm, expressed as a maximum theoretical
emissions concentration. The proposed floor level was 55 g/
dscm. (61 FR at 17408.) In the May 1997 NODA, we concluded that the
floor control and emission level for existing sources for low volatile
metals would also be appropriate for new sources. Floor control was
based on a combination of good particulate matter control and limiting
hazardous waste feedrate of low volatile metals to control emissions.
We used a breakpoint analysis of the low volatile metal emissions data
to exclude sources achieving substantially poorer low volatile metal
control than the majority of sources. The NODA floor was 37 g/
dscm. (62 FR at 24235.)
In the final rule, in response to general comments on the May 1997
NODA, we use a revised engineering evaluation and data analysis method
to establish the floor emission level for low volatile metals. We use
the aggregate feedrate approach in conjunction with floor control for
particulate matter of 57 mg/dscm to identify a low volatile metal floor
emission level of 110 g/dscm.
d. What Are Our Beyond-the-Floor Considerations for New Sources? In
the April 1996 NPRM and May 1997 NODA, we considered a low volatile
metal beyond-the-floor level, but determined that a beyond-the-floor
standard would not be cost-effective due to the high cost of treatment
and relatively small amount of low volatile metals removed from air
emissions. We received no comments to the contrary.
For the final rule, as discussed for existing sources, we do not
adopt a beyond-the-floor level for new sources, and conclude that the
floor emission level is appropriate. Therefore, we adopt the low
volatile metal floor level of 110 g/dscm as the emission
standard for new hazardous waste burning lightweight aggregate kilns.
7. What Are the Hydrochloric Acid and Chlorine Gas Standards?
In the final rule, we establish a standard for existing and new
lightweight aggregate kilns that limits hydrochloric acid and chlorine
gas emissions to 230 and 41 ppmv, respectively. The rationale for
adopting these standards is discussed below.
a. What Is the MACT Floor for Existing Sources? In the April 1996
proposal, we identified floor control for hydrochloric acid/chlorine
gas as either: (1) Hazardous waste feedrate control of chlorine to 1.5
g/dscm, expressed as a maximum theoretical emissions concentration; or
(2) a combination of a venturi scrubber and hazardous waste feedrate
level of 14 g/dscm, expressed as a maximum theoretical emissions
concentration. The proposed floor emission level was 2100 ppmv. (61 FR
at 17406.) In the May 1997 NODA, we used the same data analysis method
as proposed, except that a computed emissions variability factor was no
longer added. The floor emission level was 1300 ppmv. (62 FR at 24235.)
We received few comments concerning the hydrochloric acid/chlorine
gas floor methodology and emission level. One commenter supports the
use of a variability factor in calculating the floor emission level.
Generally, the final emission standards, including hydrochloric acid/
chlorine gas, already accounts for emissions variability without adding
a statistically-derived emissions variability factor. This issue and
our response to it are discussed in detail in the floor methodology
section in Part Four, Section V.
For today's rule, we use a revised engineering evaluation and data
analysis method to establish the MACT floor level for hydrochloric acid
and chlorine gas. The aggregate feedrate approach results in a floor
emission level of 1500 ppmv.
We estimate that approximately 31 percent of lightweight aggregate
kilns in our data base currently meet the floor emission level. The
national annualized compliance cost for sources to reduce hydrochloric
acid and chlorine gas emissions to comply with the floor level is
$350,000 for the entire hazardous waste burning lightweight aggregate
kiln industry, and will reduce hydrochloric acid and chlorine gas
emissions by 182 Mg/yr or 10 percent from current baseline emissions.
b. What Are Our Beyond-the-Floor Considerations for Existing
Sources? In the April 1996 proposal, we defined beyond-the-floor
control as wet or dry lime scrubbing with a control efficiency of 90
percent. We proposed a beyond-the-floor standard of 450 ppmv, which
included a statistical variability factor. (61 FR at 17406.) In the May
1997 NODA, the beyond-the-floor standard was 130 ppmv based on wet or
dry scrubbing with a control efficiency of 90 percent. (62 FR at
24235.)
We identified three potential beyond-the-floor techniques for
control of hydrochloric acid and chlorine gas emissions: (1) Dry lime
scrubbing; (2) limiting the feed of chlorine in the hazardous waste;
and (3) limiting the feed of chlorine in the raw materials. The result
of each analysis is discussed below.
Dry Lime Scrubbing. Based on a joint emissions testing program with
Solite Corporation in 1997, dry lime scrubbing at a stoichiometric lime
ratio of 3:1 achieved greater than 85 percent removal of hydrochloric
acid and chlorine gas. For the final rule, we considered a beyond-the-
floor emission level of 230 ppmv based on a 85 percent removal
efficiency from the floor level of 1500 ppmv.
[[Page 52900]]
The national incremental annualized compliance cost for all
lightweight aggregate kilns to meet this beyond-the-floor level is
approximately $1.5 million. This would provide an incremental reduction
in hydrochloric acid/chlorine gas emissions beyond the MACT floor
controls of an additional 1320 Mg/yr, or 80 percent. Based on these
costs of approximately $1,100 per additional Mg hydrochloric acid/
chlorine gas removed, this hydrochloric acid/chlorine gas beyond-the-
floor option for lightweight aggregate kilns is justified. Therefore,
we are adopting a beyond-the-floor standard of 230 ppmv for existing
lightweight aggregate kilns.
One commenter disagreed with our proposal to base the beyond-the-
floor standard on dry lime scrubbing achieving 90% removal. The
commenter states that dry lime scrubbing cannot cost-effectively
achieve 90 percent control of hydrochloric acid and chlorine gas
emissions. To achieve a 90 percent capture efficiency at a
stoichiometric ratio of 3:1, the commenter maintains that a source
would need to install special equipment and make operational
modifications that are less cost-effective than simple dry lime
scrubbing at a lower removal efficiency. The commenter identifies this
lower level of control at 80 percent based on the joint emissions
testing program.169 The commenter does agree, however, that
dry lime scrubbing can achieve 90 percent capture without the
installation of special equipment by operating at a stoichiometric lime
ratio greater than 3:1. One significant consequence of operating at
higher stoichiometric lime ratios, the commenter states, is the adverse
impact to the collected particulate matter. Currently, the collected
particulate matter is recycled into the lightweight aggregate product.
At higher stoichiometric lime ratios, unreacted lime and collected
chloride and sulfur salts would prevent this recycling practice and
would require the disposal of all the collected particulate matter at
significant and unjustified costs.
---------------------------------------------------------------------------
\169\ See ``Final Technical Support Document for HWC MACT
Standards, Volume III: Selection of MACT Standards and
Technologies,'' July 1999.
---------------------------------------------------------------------------
We agree with the commenter that data from the joint emissions
testing program does not support a 90 percent capture efficiency by
simple dry lime scrubbing at a stoichiometric lime ratio of 3:1. We
disagree with the commenter that the data support an efficiency no
greater than 80 percent. In the testing program, we evaluated the
capture efficiency of lime during four runs at a stoichiometric lime
ratio of approximately 3:1. The results show that hydrochloric acid was
removed at rates ranging from 86 to 91 percent with one exception. For
that one run, the removal was calculated as 81 percent. For reasons
detailed in the Comment Response Document and in the technical support
document,170 we conclude that the data from this run should
not be considered because the calculated stoichiometric lime ratio is
suspect. When we remove this data point from consideration, the
available information clearly indicates that dry lime scrubbing at a
stoichiometric ratio of 3:1 can achieve greater than 85 percent
removal. Therefore, in the final rule, we base the beyond-the-floor
standard of 230 ppmv on 85 percent removal.
---------------------------------------------------------------------------
\170\ See ``Final Technical Support Document for HWC MACT
Standards, Volume III: Selection of MACT Standards and
Technologies,'' July 1999.
---------------------------------------------------------------------------
Limiting the Feedrate of Chlorine in the Hazardous Waste. We also
considered a beyond-the-floor standard for hydrochloric acid/chlorine
gas based on additional feedrate control of chlorine in the hazardous
waste. This option achieves lower emission reductions and is less cost-
effective than the dry lime scrubbing option discussed above.
Therefore, we are not adopting a hydrochloric acid/chlorine gas beyond-
the-floor standard based on limiting the feed of chlorine in the
hazardous waste.
Limiting the Feedrate of Chlorine in the Raw Materials. A source
can achieve a reduction in hydrochloric acid/chlorine gas emissions by
substituting a feed material containing lower levels of chlorine for a
primary raw material higher chlorine levels. This beyond-the-floor
option appears to be less cost effective compared to either of the
options evaluated above because lightweight aggregate kilns are sited
proximate to primary raw material supply. Transporting large quantities
of an alternative source of raw material(s) is expected to be very
costly and not cost-effective considering the limited emissions
reductions that would be achieved. Therefore, we do not adopt this
hydrochloric acid/chlorine gas beyond-the-floor standard.
In summary, we establish the hydrochloric acid/chlorine gas
standard for existing lightweight aggregate kilns at 230 ppmv based on
scrubbing.
c. What Is the MACT Floor for New Sources? In the April 1996
proposal, we defined MACT floor control for new sources as a venturi
scrubber with a hazardous waste feedrate level of 14 g/dscm, expressed
as a maximum theoretical emissions concentration. We proposed a floor
emission level of 62 ppmv. (61 FR at 17409.) In the May 1997 NODA, we
concluded that the floor control and emission level for existing
sources for hydrochloric acid/chlorine gas would also be appropriate
for new sources. Floor control was based on limiting hazardous waste
feedrates of chlorine to control hydrochloric acid/chlorine gas
emissions. We screened out some data with anomalous system removal
efficiencies compared to the majority of sources. The floor emission
level for new lightweight aggregate kilns was 43 ppmv. (62 FR at
24235.)
In the final rule, we use a similar engineering evaluation and data
analysis method as discussed in the May 1997 NODA to establish the
floor emission level for hydrochloric acid/chlorine gas. We identified
MACT floor control as wet scrubbing since the best controlled source is
using this control technology. One lightweight aggregate facility uses
venturi-type wet scrubbers for the control of hydrochloric acid/
chlorine gas. We evaluated the chlorine system removal efficiencies
achieved by wet scrubbing at this facility. Our data show that this
facility is consistently achieving greater than 99 percent control of
hydrochloric acid/chlorine gas. Because we have no data with system
removal efficiencies indicative of poor performance, we conclude that
all data from this facility are reflective of MACT control (wet
scrubbers), and, therefore, the floor emission limit for new sources is
set equal to the highest test condition average of these data. Thus,
the MACT floor emission limit for new lightweight aggregate kilns is
identified as 41 ppmv.
d. What Are Our Beyond-the-Floor Considerations for New Sources? In
the April 1996 proposal and May 1997 NODA, we did not propose a beyond-
the-floor standard for new sources because the floor emission level was
based on wet scrubbing, which is the best available control technology
for hydrochloric acid/chlorine gas. (61 FR at 17409 and 62 FR at
24235.) We continue to believe that a beyond-the-floor emission level
for new sources is not warranted due to the high costs of treatment and
the small additional amount of chlorine that would be removed.
Therefore, the MACT standard for new lightweight aggregate kilns is
identified as 41 ppmv.
8. What Are the Hydrocarbon and Carbon Monoxide Standards?
In the final rule, we establish hydrocarbon and carbon monoxide
standards as surrogates to control emissions of nondioxin organic
hazardous air pollutants for existing and
[[Page 52901]]
new lightweight aggregate kilns. The standards limit hydrocarbon and
carbon monoxide concentrations to 20 ppmv 171 or 100 ppmv,
172 respectively. Existing and new lightweight aggregate
kilns can elect to comply with either the hydrocarbon limit or the
carbon monoxide limit on a continuous basis. Lightweight aggregate
kilns that choose to comply with the carbon monoxide limit on a
continuous basis must also demonstrate compliance with the hydrocarbon
standard during the comprehensive performance test. However, continuous
hydrocarbon monitoring following the performance test is not
required.173 We discuss the rationale for establishing these
standards below.
---------------------------------------------------------------------------
\171\ Hourly rolling average, reported as propane, dry basis and
corrected to 7 percent oxygen.
\172\Hourly rolling average, dry basis, corrected to 7 percent
oxygen.
\173\As discussed in Part 5, Section X.F, lightweight aggregate
kilns that feed hazardous waste at a location other than the end
where products are normally discharged and where fuels are normally
fired must comply with the 20 ppmv hydrocarbon standards (i.e.,
these sources do not have the option to comply with the carbon
monoxide standard).
---------------------------------------------------------------------------
a. What Is the MACT Floor for Existing Sources? As discussed in
Part Four, Section II.A.2, we proposed limits on hydrocarbon and carbon
monoxide emissions as surrogates to control nondioxin organic hazardous
air pollutants. In the April 1996 NPRM, we identified floor control as
combustion of hazardous waste under good combustion practices to
minimize the generation of fuel-related hydrocarbons. We proposed a
hydrocarbon emission level of 14 ppmv and a carbon monoxide level of
100 ppmv. The hydrocarbon level was based on an analysis of the
available emissions data, while the basis of the carbon monoxide level
was existing federal regulations (see Sec. 266.104(b)). (61 FR at
17407.) In the May 1997 NODA, we solicited comment a hydrocarbon
emission level of 10 ppmv. The hydrocarbon floor level was changed to
10 ppmv from 14 ppmv because of a change in the lightweight aggregate
kiln universe of facilities. The lightweight aggregate kiln with the
highest hydrocarbon emissions stopped burning hazardous waste. With the
exclusion of the hydrocarbon data from this one source, the remaining
lightweight aggregate kilns appeared to be able to meet a hydrocarbon
standard on the order of 6 ppmv. However, since we were unable to
identify an engineering reason why lightweight aggregate kilns using
good combustion practices should be able to achieve lower hydrocarbon
emissions than incinerators, we indicated that it may be more
appropriate to establish the hydrocarbon standard at 10 ppmv, which was
equal to the incinerator emission level discussed in that NODA. In the
NODA, we also continued to indicate our preference for a carbon
monoxide emission level of 100 ppmv. (62 FR at 24235.)
One commenter states that some lightweight aggregate kilns may not
be able to meet a 10 ppmv hydrocarbon standard due to organics in raw
materials. Notwithstanding our data base of short-term data indicating
the achievability of a hydrocarbon standard of 10 ppmv, the commenter
states that this standard may be unachievable over the long-term
because trace levels of organic matter in the raw materials vary
significantly. Hydrocarbon emissions could increase as the source uses
raw materials from different on-site quarry locations. Thus, the
commenter supports a hydrocarbon emission level consistent with cement
kilns (i.e., 20 ppmv), and opposes a floor emission level that is
comparable to incinerators for which low temperature organics
desorption from raw materials is not a complicating issue.
Our limited hydrocarbon data, as discussed above, indicates that a
hydrocarbon level of 10 ppmv is achievable for lightweight aggregate
kilns.174 However, we agree that over long-term operations,
lightweight aggregate kilns may encounter variations in the level of
trace organics in raw materials, similar to cement kilns, that may
preclude some kilns from achieving a hydrocarbon limit of 10 ppmv.
Thus, we conclude that a hydrocarbon emission level of 20 ppmv, the
same floor level for cement kilns, is also appropriate for lightweight
aggregate kilns. A hydrocarbon standard of 20 ppmv also is based on
existing federally-enforceable RCRA regulations, to which lightweight
aggregate kilns are currently subject. (See Sec. 266.104(c).)
---------------------------------------------------------------------------
\174\ Our data base for hydrocarbons consists of short-term
emissions data.
---------------------------------------------------------------------------
Some commenters also support a requirement for both a carbon
monoxide and hydrocarbon limit for lightweight aggregate kilns. These
commenters state that requiring both hydrocarbon and carbon monoxide
limits would further reduce emissions of organic hazardous air
pollutants. One commenter notes that 83 percent of existing lightweight
aggregate kilns are currently achieving both a hydrocarbon level of 20
ppmv and a carbon monoxide standard of 100 ppmv.
We carefully considered the merits and drawbacks to requiring both
a hydrocarbon and carbon monoxide standard. First, stack gas carbon
monoxide levels may not be a universally reliable indicator of
combustion intensity and efficiency for some lightweight aggregate
kilns due, first, to carbon monoxide generation by disassociation of
carbon dioxide to carbon monoxide at high temperatures and, second, to
evolution of carbon monoxide from the trace organic constituents in raw
material feedstock.175 One commenter supports our view by
citing normal variability in carbon monoxide levels at their kiln with
no apparent relationship to combustion conditions, such as temperature,
residence time, excess oxygen levels. Thus, carbon monoxide can be
overly conservative surrogate for some kilns.176
---------------------------------------------------------------------------
\175\ Raw materials enter the upper end of the kiln and move
counter-current to the combustion gas. Thus, as the raw materials
are convectively heated in the upper end kiln above the flame zone,
organic compounds can evolve from trace levels of organics in the
raw materials. These organic compounds can be measured as
hydrocarbons, and when only partially oxidized, carbon monoxide.
This process is not related to combustion of hazardous waste or
other fuels in the combustion zone at the other end of the kiln.
\176\ Of course, if a source elects to comply with the carbon
monoxide standard, then we are sure that it is achieving good
combustion conditions and good control of organic hazardous air
pollutants that could be potentially emitted from hazardous waste
fed into the combustion zone.
---------------------------------------------------------------------------
Second, requiring both continuous monitoring of carbon monoxide and
hydrocarbon in the stack is at least somewhat redundant for control of
organic emissions from combustion of hazardous waste because: (1)
Hydrocarbons alone are a direct and reliable surrogate for measuring
the destruction of organic hazardous air pollutants; and (2) carbon
monoxide is generally a conservative indicator of good combustion
conditions and thus good control of organic hazardous air pollutants.
See Part Four, Section IV.B of the preamble for a discussion of our
approach to using carbon monoxide or hydrocarbons to control organic
emissions.
We identify a carbon monoxide level of 100 ppmv and a hydrocarbon
level of 20 ppmv as floor control for existing sources because they are
existing federally enforceable standards for hazardous waste burning
lightweight aggregate kilns. See Sec. 266.104(b) and (c). As current
rules allow, sources would have the option of complying with either
limit. Given that these are current rules, all lightweight aggregate
kilns can currently achieve these emission levels. Thus, we estimate no
emissions reductions or costs for these floor levels.
Lightweight aggregate kilns that choose to continuously monitor and
[[Page 52902]]
comply with the carbon monoxide standard must demonstrate during the
performance test that they are also in compliance with the hydrocarbon
emission standard. In addition, kilns that monitor carbon monoxide
alone must also set operating limits on key parameters that affect
combustion conditions to ensure continued compliance with the
hydrocarbon emission standard. We developed this modification because
of some limited data that show a source can produce high hydrocarbon
emissions while simultaneously producing low carbon monoxide emissions.
We conclude from this information that it is necessary to confirm the
carbon monoxide-hydrocarbon emissions relationship for every source
that selects to monitor carbon monoxide emissions alone. See discussion
in Part Four, Section IV.B.
b. What Are Our Beyond-the-Floor Considerations for Existing
Sources? In the April 1996 proposal, we identified beyond-the-floor
control levels for carbon monoxide and hydrocarbon in the main stack of
50 ppmv and 6 ppmv, respectively. (61 FR at 17407.) These beyond-the-
floor levels were based on the use of a combustion gas afterburner. We
indicated in the proposal, however, that this type of beyond-the-floor
control would be cost prohibitive. Our preliminary estimates suggested
that going beyond-the-floor for carbon monoxide and hydrocarbons would
more than double the national costs of complying with the proposed
standards. We continue to believe that a beyond-the-floor standard for
carbon monoxide and hydrocarbons based on an afterburner is not
justified and do not adopt a beyond-the-floor standard for existing
lightweight aggregate kilns.
In summary, we adopt the floor emission levels for hydrocarbons, 20
ppmv, or carbon monoxide, 100 ppmv, as standards in the final rule.
c. What Is the MACT Floor for New Sources? In the April 1996 NPRM,
we identified MACT floor control as operating the kiln under good
combustion practices. Because we were unable to quantify good
combustion practices, floor control for the single best controlled
source was the same as for existing sources. We proposed, therefore, a
floor emission level of 14 ppmv for hydrocarbons and a 100 ppmv limit
for carbon monoxide. (61 FR at 17409.) In the May 1997 NODA, we
continued to identify MACT floor control as good combustion practices
and we took comment on the same emission levels as existing sources: 20
ppmv for hydrocarbons and 100 ppmv for carbon monoxide. (62 FR at
24235.)
In developing the final rule, we considered the comment that the
rule should allow compliance with either a carbon monoxide standard of
100 ppmv or a hydrocarbon standard of 20 ppmv. Given that this option
is available under the existing regulations for new and existing
sources, we conclude that this represents MACT floor for new sources.
These emission levels are achieved by operating the kiln under good
combustion practices to minimize fuel-related hydrocarbons and carbon
monoxide emissions. As current rules allow, sources would have the
option of complying with either limit. See Sec. 266.104(b) and (c).
We also considered site selection based on availability of
acceptable raw material hydrocarbon content as an approach to establish
a hydrocarbon emission level at new lightweight aggregate kilns. This
approach is similar to that done for new hazardous waste burning cement
kilns at greenfield sites (see discussion above). For cement kilns, we
finalize a new source floor hydrocarbon emission standard at a level
consistent with the proposed standard for nonhazardous waste burning
cement kilns. Because we are planning to issue MACT emission standards
for nonhazardous waste lightweight aggregate kiln sources, we will
revisit establishing a hydrocarbon standard at new lightweight
aggregate kilns at that time so that a hydrocarbon standard, if
determined appropriate, is consistent for these sources. We are
deferring this decision to a later date to ensure that hazardous waste
sources are regulated no less stringently than nonhazardous waste
lightweight aggregate kilns.
In summary, we are identifying a carbon monoxide level of 100 ppmv
and a hydrocarbon level of 20 ppmv as floor control for new sources
because they are existing federally enforceable standards for hazardous
waste burning lightweight aggregate kilns. As discussed for existing
sources above, lightweight aggregate kilns that choose to continuously
monitor and comply with the carbon monoxide standard must demonstrate
during the performance test that they are also in compliance with the
hydrocarbon emission standard.
d. What Are Our Beyond-the-Floor Considerations for New Sources? In
the April 1996 proposal, we identified beyond-the-floor emission levels
for hydrocarbons and carbon monoxide of 6 ppmv and 50 ppmv,
respectively for new sources. These beyond-the-floor levels were based
on the use of a combustion gas afterburner. (61 FR at 17409.) We
indicated in the proposal, however, that beyond-the-floor control was
not justified due to the significant costs to retrofit kilns with
afterburner controls. We estimated that going beyond-the-floor for
hydrocarbons and carbon monoxide would more than double the national
costs of complying with the proposed standards. We concluded that
beyond-the-floor standards were not warranted. In the May 1996 NODA, we
again indicated that a beyond-the-floor standard based on use of an
afterburner would not be cost-effective and, therefore, justified. As
discussed above for existing sources, we conclude that a beyond-the-
floor standard for carbon monoxide and hydrocarbons based on use of an
afterburner would not be justified and do not adopt a beyond-the-floor
standard for new lightweight aggregate kilns. (62 FR 24235.)
In summary, we adopt the floor emission levels for hydrocarbons, 20
ppmv, or carbon monoxide, 100 ppmv, as standards in the final rule.
9. What Are the Standards for Destruction and Removal Efficiency?
We establish a destruction and removal efficiency (DRE) standard
for existing and new lightweight aggregate kilns to control emissions
of organic hazardous air pollutants other than dioxins and furans.
Dioxins and furans are controlled by separate emission standards. See
discussion in Part Four, Section IV.A. The DRE standard is necessary,
as previously discussed, to complement the carbon monoxide and
hydrocarbon emission standards, which also control these hazardous air
pollutants.
The standard requires 99.99 percent DRE for each principal organic
hazardous constituent (POHC), except that 99.9999 percent DRE is
required if specified dioxin-listed hazardous wastes are burned. These
wastes--F020, F021, F022, F023, F026, and F027--are listed as RCRA
hazardous wastes under part 261 because they contain high
concentrations of dioxins.
a. What Is the MACT Floor for Existing Sources? Existing sources
are currently subject to DRE standards under Sec. 266.104(a) that
require 99.99 percent DRE for each POHC, except that 99.9999 percent
DRE is required if specified dioxin-listed hazardous wastes are burned.
Accordingly, these standards represent MACT floor. Since all hazardous
waste lightweight aggregate kilns must currently achieve these DRE
standards, they represent floor control.
b. What Are Our Beyond-the-Floor Considerations for Existing
Sources? Beyond-the-floor control would be a requirement to achieve a
higher
[[Page 52903]]
percentage DRE, for example, 99.9999 percent DRE for POHCs for all
hazardous wastes. A higher DRE could be achieved by improving the
design, operation, or maintenance of the combustion system to achieve
greater combustion efficiency.
Even though the 99.99 percent DRE floor is an existing RCRA
standard, a substantial number of existing hazardous waste combustors
are not likely to be routinely achieving 99.999 percent DRE, however,
and most are not likely to be achieving 99.9999 percent DRE.
Improvements in combustion efficiency will be required to meet these
beyond-the-floor DREs. Improved combustion efficiency is accomplished
through better mixing, higher temperatures, and longer residence times.
As a practical matter, most combustors are mixing-limited and may not
easily achieve 99.9999 percent DRE. For a less-than-optimum burner, a
certain amount of improvement may typically be accomplished by minor,
relatively inexpensive combustor modifications--burner tuning
operations such as a change in burner angle or an adjustment of swirl--
to enhance mixing on the macro-scale. To achieve higher DREs, however,
improved mixing on the micro-scale may be necessary. This involves
significant, energy intensive and expensive modifications such as
burner redesign and higher combustion air pressures. In addition,
measurement of such DREs may require increased spiking of POHCs and
more sensitive stack sampling and analysis methods at added expense.
Although we have not quantified the cost-effectiveness of a beyond-
the-floor DRE standard, it would not appear to be cost-effective. For
reasons discussed above, the cost of achieving each successive order-
of-magnitude improvement in DRE will be at least constant, and more
likely increasing. Emissions reductions diminish substantially,
however, with each order of magnitude improvement in DRE. For example,
if a source were to emit 100 gm/hr of organic hazardous air pollutants
assuming zero DRE, it would emit 10 gm/hr at 90 percent DRE, 1 gm/hr at
99 percent DRE, 0.1 gm/hr at 99.9 percent DRE, 0.01 gm/hr at 99.99
percent DRE, and 0.001 gm/hr at 99.999 percent DRE. If the cost to
achieve each order of magnitude improvement in DRE is roughly constant,
the cost-effectiveness of DRE decreases with each order of magnitude
improvement in DRE. Consequently, we conclude that this relationship
between compliance cost and diminished emissions reductions suggests
that a beyond-the-floor standard is not warranted in light of the
resulting, poor cost-effectiveness.
c. What Is the MACT Floor for New Sources? The single best
controlled source, and all other hazardous waste lightweight aggregate
kilns, are subject to the existing RCRA DRE standard under
Sec. 266.104(a). Accordingly, we adopt this standard of 99.99% DRE for
most wastes and 99.9999% DRE for dioxin listed wastes as the MACT floor
for new sources.
d. What Are Our Beyond-the-Floor Considerations for New Sources? As
discussed above, although we have not quantified the cost-effectiveness
of a more stringent DRE standard, diminishing emissions reductions with
each order of magnitude improvement in DRE suggests that cost-
effectiveness considerations would likely come into play. We conclude
that a beyond-the-floor standard is not warranted.
Part Five: Implementation
I. How Do I Demonstrate Compliance with Today's Requirements?
If you operate a hazardous waste burning incinerator, cement kiln,
or lightweight aggregate kiln, you are required to comply with the
standards and requirements in today's rule at all times, with one
exception. If you are not feeding hazardous waste to the combustion
device and if hazardous waste does not remain in the combustion
chamber, these rules do not apply under certain conditions discussed
below. You must comply with all of the notification requirements,
emission standards, and compliance and monitoring provisions of today's
rule by the compliance date, which is three years after September 30,
1999. As referenced later, the effective date of today's rule is
September 30, 1999. The compliance and general requirements of this
rule are discussed in detail in the follow sections. Also, we have
included the following time line that will assist you in determining
when many of the notifications and procedures, discussed in the later
sections of this part, are required to be submitted or accomplished.
A. What Sources Are Subject to Today's Rules?
Sources affected by today's rule are defined as all incinerators,
cement kilns and lightweight aggregate kilns burning hazardous waste
on, or following September 30, 1999. This definition is essentially the
same as we proposed in the April 1996 NPRM. Comments, regarding this
definition, suggested that there was confusion as to when and under
what conditions you would be subject to today's hazardous waste MACT
regulations. In this rule, we specify that once you are subject to
today's regulations, you remain subject to these regulations until you
comply with the requirements for sources that permanently suspend
hazardous waste burning operations, as discussed later.
However, just because you are subject to today's regulations does
not mean that you must comply with the emission standards or operating
limits at all times. In later sections of today's rule, we identify
those limited periods and situations in which compliance with today's
emission standards and operating limits may not be required.
1. What Is an Existing Source?
Today's rule clarifies that existing sources are sources that were
constructed or under construction on the publication date for our
NPRM---April 19, 1996. This is consistent with the current regulatory
definition of existing sources, but is different from the definition in
our April 1996
NPRM. In the April 1996 NPRM, we defined existing sources as those
burning hazardous waste on the proposal date (April 19, 1996) and
defined new sources as sources that begin burning hazardous waste after
the proposal date. Commenters note that the proposed definition of new
sources is not consistent with current regulations found in 40 CFR part
63 or the Clean Air Act. Commenters also believe that our definition
does not consider the intent of Congress, i.e., to require only those
sources that incur significant costs during upgrade or modification to
meet the most stringent new source emission standards. Commenters note
that a large number of sources that are currently not burning hazardous
waste could modify their combustion units to burn hazardous waste at a
cost that would not surpass the reconstruction threshold and therefore
they should not be required to meet the new source emission standards.
Commenters suggest we use the statutory definition of an existing
source found at section 112(a)(4) of the CAA and codified at 40 CFR
63.2. We agree with commenters and therefore adopt the definition of an
existing source found at 40 CFR 63.2.
2. What Is a New Source?
Today's rule clarifies that new sources are those that commence
construction or meet the definition of a reconstructed source following
the proposal date of April 19, 1996. In the proposal, we define new
sources as those that newly begin to burn hazardous waste after the
proposal date. However, as noted earlier, commenters object to the
[[Page 52904]]
proposed definition because of conflicts with the statutory language of
the CAA and the current definition found in MACT regulations. In the
CAA regulations, we define new sources as those that are newly
constructed or reconstructed after a rule is proposed. Here again, we
agree with commenters and adopt the current regulatory definition of
new sources. We also adopt the CAA definition of reconstruction. This
definition also is generally consistent with the RCRA definition of
reconstruction and should avoid any confusion regarding what standards
apply to reconstructed sources.
B. How Do I Cease Being Subject to Today's Rule?
Once you become an affected source as defined in Sec. 63.2, you
remain an affected source until you: (1) Cease hazardous waste burning
operations, (i.e., hazardous waste is not in the combustion chamber);
(2) notify the Administrator, and other appropriate regulatory
authorities, that you have ceased hazardous waste burning operations;
and (3) begin complying with other applicable MACT standards and
regulations, if any, including notifications, monitoring and
performance tests requirements.
If you permanently stop burning hazardous waste, the RCRA
regulations require you to initiate closure procedures within three
months of the date you received your last shipment of hazardous waste,
unless you have obtained an extension from the Administrator. The
requirement to initiate closure pertains to your RCRA status and should
not be a barrier to operational changes that affect your regulatory
status under today's MACT requirements. This approach is a departure
from the requirements proposed in the April 1996 NPRM, but is
consistent with the approach we identified in the May 1997 NODA.
Once you permanently stop burning hazardous waste, you may only
begin burning hazardous waste under the procedures outlined for new or
existing sources that become affected sources following September 30,
1999. See later discussion.
C. What Requirements Apply If I Temporarily Cease Burning Hazardous
Waste?
Under today's rule, if you temporarily cease burning hazardous
waste for any reason, you remain subject to today's requirements as an
affected source. However, even as an affected source, you may not have
to comply with the emission standards or operating limits of today's
rule when hazardous waste is not in the combustion chamber. Today's
standards, associated operating parameter limits, and monitoring
requirements are applicable at all times unless hazardous waste is not
in the combustion chamber and either: (1) You elect to comply with
other MACT standards that would be applicable if you were not burning
hazardous waste (e.g. the nonhazardous waste burning Portland Cement
Kiln MACT, the nonhazardous waste burning lightweight aggregate kiln
MACT (Clay Products Manufacturing), or the Industrial Incinerator
MACT); or (2) you are in a startup, shutdown, or malfunction mode of
operation. We note that until these alternative MACT standards are
promulgated, you need to comply only with other existing applicable air
requirements if any. This approach is consistent with the current RCRA
regulatory approach for hazardous waste combustion sources, but differs
from our April 1996 proposed approach.
In our April 1996 NPRM, we proposed that sources always be subject
to all of the proposed regulatory requirements, regardless of whether
hazardous waste was in the combustion chamber. Commenters question the
legitimacy of this requirement because the requirement was: (1) more
stringent than current requirements; (2) not based on CAA statutory
authority; and (3) contrary to current allowances under current MACT
general provisions.
In response, we agree with commenters on issues (1) and (3) above.
However, we disagree with commenters on issue number (2). The CAA does
not allow sources to be subject to multiple MACT standards
simultaneously. Because current CAA regulations also allow sources to
modify their operations such that they can become subject to different
MACT rules so long as they provide notification to the Administrator,
our proposed approach appears to further complicate a situation that it
was intended to resolve. One of the main reasons we proposed to subject
hazardous waste burning sources to the final standards at all times was
to eliminate the ability of sources to arbitrarily switch between
regulation as a hazardous waste burning source and regulation as a
nonhazardous waste burning source. We were concerned about the
compliance implications associated with numerous notifications to the
permitting authority to govern operations that may only occur for a
short period of time. However, our concern appears unfounded because
the MACT general provisions currently allow sources to change their
regulatory status following notification, and we cannot achieve this
goal without restructuring the entire MACT program. Therefore,
consistent with the current program, we adopt an approach that allows a
source to comply with alternative compliance requirements, while
remaining subject to today's rule. This regulatory approach eliminates
the reporting requirements and compliance determinations we intended to
avoid with our proposed approach, while preserving the essence of the
current RCRA approach, which applies more stringent emissions standards
when hazardous waste is in the combustor.
1. What Must I Do to Comply with Alternative Compliance Requirements?
If you wish to comply with alternative compliance requirements, you
must: (1) Comply with all of the applicable notification requirements
of the alternative regulation; (2) comply with all the monitoring,
record keeping and testing requirements of the alternative regulation;
(3) modify your Notice Of Compliance (or Documentation of Compliance)
to include the alternative mode(s) of operation; and (4) note in your
operating record the beginning and end of each period when complying
with the alternative regulation.
If you intend to comply with an alternative regulation for longer
than three months, then you also must comply with the RCRA requirements
to initiate RCRA closure. You may be able to obtain an extension of the
date you are required to begin RCRA closure by submitting a request to
the Administrator.
2. What Requirements Apply If I Do Not Use Alternative Compliance
Requirements?
If you elect not to use the alternative requirements for compliance
during periods when you are not feeding hazardous waste, you must
comply with all of the operating limits, monitoring requirements, and
emission standards of this rule at all times.177 However, if
you are a kiln operator, you also may be able to obtain and comply with
the raw material variance discussed later.
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\177\ The operating requirements do not apply during startup,
shutdown, or malfunction provided that hazardous waste is not in the
combustion chamber. See the discussion below in the text.
---------------------------------------------------------------------------
D. What Are the Requirements for Startup, Shutdown and Malfunction
Plans?
Sources affected by today's rule are subject to the provisions of
40 CFR 63.6 with regard to startup, shutdown and malfunction plans.
However, the plan applies only when hazardous waste is
[[Page 52905]]
not in the combustion chamber. If you exceed an operating requirement
during startup, shutdown, or malfunction when hazardous waste is in the
combustion chamber, your exceedance is not excused by following your
plan. If you exceed an operating requirement during startup, shutdown,
or malfunction when hazardous waste is not in the combustion chamber,
you must follow your startup, shutdown, and malfunction plan to come
back into compliance as quickly as possibly, unless you have elected to
comply with the requirements of alternative section 112 or 129
regulations that would apply if you did not burn hazardous waste.
Failure to comply with the operating requirements to follow your
startup, shutdown, and malfunction plan during the applicable periods
is representative of a violation and may subject you to appropriate
enforcement action.
In the April 1996 NPRM (see 63 FR at 17449), we proposed that
startup, shutdown, and malfunction plans would not be applicable to
sources affected by the proposed rule because affected sources must be
in compliance with the standards at all times hazardous waste is in the
combustion chamber. We reasoned that hazardous waste could not be fired
unless you were in compliance with the emission standards and operating
requirements, and stated that the information contained in the plan and
the purpose of the plan was not intended to apply to sources affected
by this rule.
In response, commenters state that startup, shutdown, and
malfunction plans are appropriate for hazardous waste burning sources
because malfunctioning operations are going to occur, and these plans
are designed to reestablish compliant or steady state operations as
quickly as possible. Furthermore, commenters maintain that because
sources must prepare and follow facility-specific plans to address
situations that could lead to increased emissions, rather than just
note such an occurrence in the operating record, the public and we are
better assured that the noncompliant operations are being remedied
rather than awaiting for an after-the-fact enforcement action.
Commenters also note that hazardous waste burning sources are no
different than other MACT sources who are required to use such plans.
After considering comments, we agree with commenters that startup,
shutdown, and malfunction plans are valuable compliance tools and
should be applicable to hazardous waste burning sources. However, we
are concerned that some sources may attempt to use startup, shutdown,
and malfunction plans to circumvent enforcement actions by claiming
they were never out of compliance if they followed their plan.
Therefore, we restrict the applicability of startup, shutdown, and
malfunction plans to periods when hazardous waste is not in the
combustion chamber. This restriction addresses the concern that
operations under startup, shutdown, and malfunction could lead to
increased emissions of hazardous air pollutants.
We considered whether to specifically prohibit sources from feeding
hazardous waste during periods of startup and shutdown. However, we
decided not to adopt this requirement because of a potential regulatory
problem. The requirement could have inadvertently subjected sources
that experience unscheduled shutdowns to enforcement action if
hazardous waste remained in the combustion chamber during the shutdown
process even if operating requirements were not exceeded. Additionally,
we decided that the prohibition was unnecessary because performance
test protocols restrict the operations of all sources when determining
operating parameter limits. The following factors are pertinent in this
regard: (1) Sources are required to be in compliance with their
operating parameter limits at all times hazardous waste is in the
combustion chamber; (2) operating parameter limits are determined
through a performance test which must be performed under steady-state
conditions (see Sec. 63.1207(g)(1)(iii)); and (3) periods of startup
and shutdown are not steady state conditions and therefore operating
parameter limits determined through performance testing would not be
indicative of those periods. Accordingly, burning hazardous waste
during startup or shutdown would significantly increase the potential
for a source to exceed an operating parameter limit, and we expect that
sources would be unwilling to take that chance as a practical matter.
E. What Are the Requirements for Automatic Waste Feed Cutoffs?
As proposed, you must operate an automatic waste feed cutoff system
that immediately and automatically cuts off hazardous waste feed to the
combustion device when:
(1) Any of the following are exceeded: Operating parameter limits
specified in Sec. 63.1209; an emission standard monitored by a
continuous emissions monitoring system; and the allowable combustion
chamber pressure; (2) The span value of any continuous monitoring
system, except a continuous emissions monitoring system, is met or
exceeded; (3) A continuous monitoring system monitoring an operating
parameter limit under Sec. 63.1209 or emission level malfunctions; or
(4) Any component of the automatic waste feed cutoff system fails.
These requirements are provided at Sec. 63.1206(c)(3). The system
must be fully functional on the compliance date and interlocked with
the operating parameter limits you specify in the Document of
Compliance (as discussed later) as well as the other parameters listed
above.
Also as proposed, after an automatic waste feed cutoff, you must
continue to route combustion gases through the air pollution control
system and maintain minimum combustion chamber temperature as long as
hazardous waste remains in the combustion chamber. These requirements
minimize emissions of regulated pollutants, including organic hazardous
air pollutants, that could result from a perturbation caused by the
waste feed cutoff. Additionally, you must continue to calculate all
rolling averages and cannot restart feeding hazardous waste until all
operating limits are within allowable levels.
Additionally, as currently required for BIFs, we proposed that the
automatic waste feed cutoff system and associated alarms must be tested
at least once every seven days. This must be done when hazardous waste
is burned to verify operability, unless you document in the operating
record that weekly inspections will unduly restrict or upset operations
and that less frequent inspections will be adequate. At a minimum, you
must conduct operational testing at least once every 30 days.
Commenters express the following concerns with the proposed
automatic waste feed cutoff requirements: (1) Violations of the
automatic waste feed cutoff linked operating parameters should not
constitute a violation of the associated emission standard; (2)
apparent redundancy exists between the proposed MACT requirements with
the current RCRA requirements; (3) the proposed automatic waste feed
cutoff requirements are inappropriate for all sources; and (4)
uncertainty exists about how ``instantaneous'' is defined with regard
to the nature of the automatic waste feed cutoff requirement.
We address issue (1) later in this section. With respect to issue
(2), our permitting approach (i.e., a single CAA title V permit to
control all stack emissions) minimizes the potential redundancy of two
permitting programs.
In response to issue (3), we acknowledge that not all sources may
be capable of setting operating limits or
[[Page 52906]]
continuously monitoring all of the prescribed operating parameters due
to unique design characteristics inherent to individual units. However,
you may take advantage of the provisions found in Sec. 63.8(f) which
allow you to request the use of alternative monitoring techniques. See
also Sec. 63.1209(g)(1).
For issue (4), commenters express concern that requiring an
immediate, instantaneous, and abrupt cutoff of the entire waste feed
can cause perturbations in the combustion system that could result in
exceedances of additional operating limits. We agree with commenters
that a ramping down of the waste feedrate could preclude this problem
in many cases and in the final rule allow a one-minute ramp down for
pumpable wastes. To ensure that your ramp down procedures are bona fide
and not simply a one-minute delay ending in an abrupt cutoff, you must
document your ramp down procedures in the operating and maintenance
plan. The procedures must specify that the ramp down begins immediately
upon initiation of automatic waste feed cutoff and provides for a
gradual ramp down of the hazardous waste feed. Note that if an emission
standard or operating limit is exceeded during the ramp down, you
nonetheless have failed to comply with the emission standards or
operating requirements. The ramp down is not applicable, however, if
the automatic waste feed cutoff is triggered by an exceedance of any of
the following operating limits: minimum combustion chamber temperature;
maximum hazardous waste feedrate; or any hazardous waste firing system
operating limits that may be established for your combustor on a site-
specific basis. This is because these operating conditions are
fundamental to proper combustion of hazardous waste and an exceedance
could quickly result in an exceedance of an emission standard. We
restrict the ramp down to pumpable wastes because: (1) Solids are often
fed in batches where ramp down is not relevant (i.e., ramp down is only
relevant to continuously fed wastes); and (2) incinerators burning
solids also generally burn pumpable wastes and ramping down on
pumpables only should preclude the combustion perturbations that could
occur if all wastes were abruptly cutoff.
Finally, with respect to issue number (1), if you exceed an
operating parameter limit while hazardous waste is in the combustion
chamber, then you have failed to ensure compliance with the associated
emission standard. Accordingly, appropriate enforcement action on the
exceedance can be initiated to address the exceedance. This enforcement
process is consistent with current RCRA enforcement procedures
regarding exceedances of operating parameter limits. However, as
commenters note, we acknowledge that an exceedance of an operating
parameter limit does not necessarily demonstrate that an associated
emissions standard is exceeded. Nevertheless, in general, an exceedance
of an operating parameter limit in a permit or otherwise required is an
actionable event for enforcement purposes.
Operating parameter limits are developed through performance tests
that successfully demonstrate compliance with the standards. If a
source exceeds an operating limit set during the performance test to
show compliance with the standard, the source can no longer assure
compliance with the associated standard. Furthermore, these operating
parameter limits appear in enforceable documents, such as your NOC or
your title V permit.
F. What Are the Requirements of the Excess Exceedance Report?
In today's rule, we finalize the requirement to report to the
Administrator when you incur 10 exceedances of operating parameter
limits or emissions standards monitored with a continuous emissions
monitoring system within a 60 day period. See Sec. 63.1206(c)(3)(vi).
If a source has 10 exceedances within the 60 day period, the 60 day
period restarts after the notification of the 10th exceedance. This
provision is intended to identify sources that have excess exceedances
due to system malfunction or performance irregularities. This
notification requirement both highlights the source to regulatory
officials and provides an added impetus to the facility to correct the
problem(s) that may exist to limit future exceedances. For example, a
source that must submit an excess exceedance report may be unable to
operate under its current operating limits, which suggests that the
source may need to perform a new comprehensive performance test to
establish more appropriate operating limits.
We discussed this provision in the April 1996 NPRM. Some commenters
may have misunderstood our proposal while others felt that 10
exceedances in sixty days was not a feasible number to set the
reporting limit. Other commenters state that an industry wide MACT-like
analysis is necessary to identify an achievable or appropriate number
of exceedances upon which to set the reporting limit.
We disagree with such comments. A MACT-like analysis is not called
for in this case because this requirement is not an emission standard.
This is a notification procedure that is a compliance tool to identify
sources that cannot operate routinely in compliance with their
operating parameter limits and emissions standards monitored with a
continuous emissions monitoring system. Ideally, all sources should
operate in compliance with all the standards and operating parameter
limits at all times. Because, in the past, sources have been able to
exceed their operating limits without having to notify the Agency, this
does not mean that we condone, expect, or are unconcerned with such
activity. In fact, the main reason we require this notification is
because such activity exists to the current extent and because the
Regions and States have identified it as a problem. We select 10
exceedances in sixty days as the value that triggers reporting after
discussions with Regional and State permit writers. Our discussions
revealed that many hazardous waste combustion sources are required to
notify regulatory officials following a single exceedance of an
operating limit, while others don't have any reporting requirements
linked to exceedances. Regions and States noted that because there is
no current regulatory requirement for exceedance notifications, it is
very difficult to require such notifications on a site-specific basis.
Following these discussions, we contemplated requiring a notification
following a single exceedance, but decided that the such a reporting
limit might unnecessarily burden regulatory officials with reports from
facilities that have infrequent exceedances. Therefore, our approach of
10 exceedances in a 60 day period is a reasonably implementable limit
and is not overly burdensome. Adopting this approach achieves an
appropriate balance between burden on facilities and regulators and the
need to identify underlying operational problems that may present
unacceptable risks to the public and environment.
To reiterate, this provision applies to any 10 exceedances of
operating parameter limits or emission standards monitored with a
continuous emissions monitoring system.
G. What Are the Requirements for Emergency Safety Vent Openings?
In today's rule, we finalize requirements that govern the operation
of emergency safety vents. See Sec. 63.1206(c)(4). These requirements:
clarify the regulatory status of emergency safety vent events; require
[[Page 52907]]
development of an emergency safety vent operating plan that specifies
procedures to minimize the frequency and duration of emergency safety
vent openings; and specify procedures to follow when an emergency
safety vent opening occurs.
Key requirements regarding emergency safety vent openings include:
(1) Treatment of combustion gases--As proposed, you must route
combustion system off-gases through the same emission control system
used during the comprehensive performance test. Any bypass of the
pollution control system is considered an exceedance of operating
limits defined in the Documentation of Compliance (DOC) or Notification
of Compliance (NOC);
(2) Emergency safety vent operating plan--As proposed, if you use
an emergency safety vent in your system design, you must develop and
submit with the DOC and NOC an emergency safety vent operating plan
that outlines the procedures you will take to minimize the frequency
and duration of emergency safety vent openings and details the
procedure you will follow during and after an emergency safety vent
opening; and
(3) Emergency safety vent reporting requirements--As proposed, if
you operate an emergency safety vent, you must submit a report to the
appropriate regulatory officials within five days of an emergency
safety vent opening. In that report, you must detail the cause of the
emergency safety vent opening and provide information regarding
corrective measures you will institute to minimize such events in the
future.
Commenters on the April 1996 NPRM (61 FR at 17440) state that
emergency safety vent openings are safety devices designed to prevent
catastrophic failures, safeguard the unit and operating personnel from
pressure excursions and protect the air pollution control train from
high temperatures and pressures. They suggest that restricting these
operations is contrary to common sense. Furthermore, they state that
emergency safety vent openings are most often due to local power
outages and fluctuations in water flows going to the air pollution
equipment. Commenters believe that emergency safety vent openings
should not be considered violations and that not every emergency safety
vent opening should be reportable for a variety of reasons including:
--Emergency safety vent openings have not been shown to be acutely
hazardous. A study finds that they will not have any short-term impact
on the health of workers on-site or residents of the nearby off-site
community.
--Proper use of emergency safety vent systems minimizes the potential
for impacts on operators and the neighboring public.
--Many emergency safety vents are downstream of the secondary
combustion chamber and thus have low organic emissions.
--Some facilities have emergency safety vents connected to the air
pollution control system and should be considered in compliance as long
as the continuous emissions monitoring systems monitoring data does not
indicate an exceedance.
Commenters propose several alternatives:
--Recording emergency safety vent openings (including the time,
duration and cause of each event) in the operating record, available to
the Administrator, or any authorized representative, upon request.
--Making emergency safety vent openings a part of startup, shutdown,
malfunction and abatement plans.
--Reporting openings that occurs more frequently than once in any 90
day period, whereupon the Administrator may require corrective
measures.
--Reporting only emergency safety vent openings in excess of 10 in a 60
day period.
--Conditions relating to an emergency safety vent operation should be a
part of the site-specific permit.
--Rely on the present RCRA permit process which provides the
opportunity for permit writers and hazardous waste combustion device
owner/operators to review emergency safety vent system designs.
We agree that emergency safety vents are necessary safety devices
for some incinerator designs that are intended to safeguard employees
and protect the equipment from the dangers associated with system over-
pressures or explosions. However, simply because emergency safety vents
are necessary safety devices for some incinerator designs in the event
of a major malfunction does not mean that their routine use is
acceptable. We cannot overlook an event when combustion gases are
emitted into the environment prior to proper treatment by the pollution
control system. Therefore, an emergency safety vent opening is evidence
that compliance is not being achieved. Nonetheless, we expect sources
to continue to use safety vents when the alternative could be a
catastrophic failure and substantial liability even though opening the
vent is evidence of failure to comply with the emission standards.
Today's requirements are based on the fundamental need to ensure
protection of human health and the environment against unquantified and
uncontrolled hazardous air pollutant emissions. We do not agree that a
change in the proposed emergency safety vent reporting requirement is
warranted. These events are indicative of serious operational problems,
and each event should be reported and investigated to reduce the
potential of future similar events. As for including the emergency
safety vent operating plan in the source-specific startup, shutdown,
and malfunction plan, we see no reason to discourage that practice
provided that a combined plan specifically addresses the events
preceding and following an emergency safety vent opening.
H. What Are the Requirements for Combustion System Leaks?
You must prevent leaks of gaseous, liquid or solid materials from
the combustion system when hazardous waste is being fed to or remains
in the combustion chamber. To demonstrate compliance with this
requirement you must either: (1) Maintain the combustion system
pressure lower than ambient pressure at all times; (2) totally enclose
the system; or (3) gain approval from the Administrator to use an
alternative approach that provides the same level of control achieved
by options 1 and 2.
Currently, these requirements exist for all sources under RCRA
regulations. Many commenters question whether they were capable of
meeting this requirement for various technical reasons. We acknowledge
that certain situations may exist that prevent or limit a source from
instantaneously monitoring pressure inside the combustion system, but
in such situations, we can approve alternative techniques (under
Sec. 63.1209(g)(1)) that allow sources to achieve the objectives of the
requirements. Because this requirement is identical to the current RCRA
requirements, and because we have specifically provided alternative
techniques to demonstrate compliance, modifications to this provision
are not warranted.
I. What Are the Requirements for an Operation and Maintenance Plan?
You must prepare and at all times operate according to a operation
and maintenance plan that describes in detail procedures for operation,
inspection, maintenance, and corrective measures for all components of
the combustor, including associated pollution control equipment, that
could affect emissions of regulated hazardous
[[Page 52908]]
air pollutants. The plan must prescribe how you will operate and
maintain the combustor in a manner consistent with good air pollution
control practices for minimizing emissions at least to the levels
achieved during the comprehensive performance test. You must record the
plan in the operating record. See Sec. 63.1206(c)(7)(i).
In addition, if you own or operate a hazardous waste incinerator or
hazardous waste burning lightweight aggregate kiln equipped with a
baghouse, your operation and maintenance plan for the baghouse must
include a prescribed inspection schedule for baghouse components and
use of a bag leak detection system to identify malfunctions. This
baghouse operation and maintenance plan must be submitted to the
Administrator with the initial comprehensive performance test for
review and approval. See Sec. 63.1206(c)(7)(ii).
We require an operation and maintenance plan to implement the
provisions of Sec. 63.6(e). That paragraph requires you to operate and
maintain your source in a manner consistent with good air pollution
control practices for minimizing emissions. That paragraph, as all
Subpart A requirements, applies to all MACT sources unless requirements
in the subpart for a source category state otherwise. In addition,
Sec. 63.6(e)(2) states that the Administrator will determine whether
acceptable operation and maintenance procedures are used by reviewing
information including operation and maintenance procedures and records.
Thus, paragraph (e)(2) effectively requires you to develop operation
and maintenance procedures. Consequently, explicitly requiring you to
develop an operation and maintenance plan is a logical outgrowth of the
proposed rule.
Similarly, although we did not prescribe baghouse inspection
requirements or require a bag leak detection system at proposal for
incinerators and lightweight aggregate kilns, this is a logical
outgrowth of the proposed rule. Section 63.6(e) requires sources to
operate and maintain emission control equipment in a manner consistent
with good air pollution control practices for minimizing emissions.
Inspection of baghouse components is required to provide adequate
maintenance, and a bag leak detection system is a state-of-the-art
monitoring system that identifies major baghouse malfunctions. Absent
use of a particulate matter CEMS or opacity monitor, use of a bag leak
detection system is an essential monitoring approach to ensure that the
baghouse continues to operate in a manner consistent with good air
pollution control practices. Bag leak detection systems are required
under the MACT standards for secondary lead smelters. See Sec. 63.548.
We have also proposed to require them as MACT requirements for several
other source categories including primary lead smelters (see 63 FR
19200 (April 17, 1998)) and primary copper smelters (see 63 FR 19581
(April 20, 1998)). In addition, we have published a guidance document
on the installation and use of bag leak detection systems: USEPA,
``Fabric Filter Bag Leak Detection,'' September 1997, EPA-454/R-98-015.
Thus, although not explicitly required at proposal, a requirement to
use bag leak detection systems is a logical outgrowth of the (proposed)
requirements of Sec. 63.6(e).
We are not prescribing a schedule for inspection of baghouse
components or requiring a bag leak detection system for cement kilns
because cement kilns must use a continuous opacity monitoring system
(COMS) to demonstrate compliance with an opacity standard. A COMS is a
better indicator of baghouse performance than a bag leak detection
system. We could not use COMS for incinerators and lightweight
aggregate kilns, however, because we do not have data to identify an
opacity standard that is achievable by MACT sources (i.e., sources
using MACT control and achieving the particulate matter standard).
We are not specifying the type of sensor that must be used other
than: (1) The system must be certified by the manufacturer to be
capable of detecting particulate matter emissions at concentrations of
1.0 milligram per actual cubic meter; and (2) the sensor must provide
output of relative particulate matter loadings. Several types of
instruments are available to monitor changes in particulate emission
rates for the purpose of detecting fabric filter bag leaks or similar
failures. The principles of operation of these instruments include
electrical charge transfer and light scattering. The guidance document
cited above applies to charge transfer monitors that use
triboelectricity to detect changes in particle mass loading, but other
types of monitors may be used. Specifically, opacity monitors may be
used.
The economic impacts of requiring fabric filter bag leak detection
systems are minimal. These systems are relatively inexpensive. They
cost less than $11,000 to purchase and install. Further, we understand
that most hazardous waste burning lightweight aggregate kilns are
already equipped with triboelectric sensors. Finally, there are few
hazardous waste incinerators that are currently equipped with fabric
filters.
II. What Are the Compliance Dates for this Rule?
A. How Are Compliance Dates Determined?
In today's rule, as with other MACT rules, we specify the
compliance date and then provide you additional time to demonstrate
compliance through performance testing. Generally, you must be in
compliance with the emission standards on September 30, 2002 unless you
are granted a site-specific extension of the compliance date of up to
one year. By September 30, 2002, you must complete modifications to
your unit and establish preliminary operating limits, which must be
included in the Documentation of Compliance (DOC) and recorded in the
operating record. Following the compliance date you have up to 180 days
to complete the initial comprehensive performance test and an
additional 90 days to submit the results of the performance test in the
Notification of Compliance (NOC). In the NOC, you also must certify
compliance with applicable emission standards and define the operating
limits that ensure continued compliance with the emission standards.
In the April 1996 NPRM, we proposed that sources comply with all
the substantive requirements of the rule on the compliance date. This
required sources to conduct their performance test as well as submit
results in the NOC by the compliance date. The compliance date
discussed in the April 1996 NPRM contained a statutory limitation of
three years following the effective date of the final rule (i.e., the
publication date of the final rule) with the possibility of a site-
specific extension of up to one year for the installation of controls
to comply with the final standards, or to allow for waste minimization
reductions.
In the May 1997 NODA, we acknowledged that the April 1996 NPRM
definition of compliance date and our approach to implementation
created a number of unforseen difficulties (see 63 FR at 24236).
Commenters note that the proposed compliance date definition and the
ramifications of noncompliance create the potential for an
unnecessarily large number of source shut-downs due to an insufficient
period to perform all the required tasks. Commenters recommend we
follow the general provisions applicable to all MACT regulated sources,
which allow sources to demonstrate compliance through
[[Page 52909]]
performance testing and submission of emission test results up to 270
days following the compliance date.
In the May 1997 NODA, we outlined an approach that allowed
facilities to use the Part 63 general approach, which requires sources
to complete performance testing within 180 days of the compliance date
and submit test results 90 days after completing the performance
test.178 Today, we adopt this approach to foster consistent
implementation of this rule as a CAA regulation.
---------------------------------------------------------------------------
\178\ The general provisions of part 63 allow for 180 days after
the compliance date to conduct a performance test and 60 days to
submit its results to the appropriate regulatory agency. However, as
commenters note, dioxin/furan analyses can require 90 days to
complete. Therefore, the time allowed for submission of test results
should be extended to 90 days, increasing the total time following
the compliance date to 270 days. We agree with commenters and
increase the time allowed for submission of test results from 60 to
90 days.
---------------------------------------------------------------------------
Your individual dates for: (1) Compliance; (2) comprehensive
performance testing; (3) submittal of test results; and (4) submittal
of your NOC and title V permit requests depend on whether you were an
existing source on April 19, 1996. Compliance dates for existing and
new sources are discussed in the following two subsections.
B. What Is the Compliance Date for Sources Affected on April 19, 1996?
The compliance date for all affected sources constructed, or
commencing construction or reconstruction before April 19, 1996 is
September 30, 2002.
C. What Is the Compliance Date for Sources That Become Affected After
April 19, 1996?
If you began construction or reconstruction after April 19, 1996,
your compliance date is the latter of September 30, 1999 or the date
you commence operations. If today's final emission standards are less
stringent or as stringent as the standards proposed on April 19, 1996,
you must be in compliance with the 1996 proposed standards upon
startup. If today's final standards are more stringent than the
proposed standards, you must be in compliance with the more stringent
standards by September 30, 2002.
III. What Are the Requirements for the Notification of Intent to
Comply?
For the reader's convenience, we summarize here the Notice of
Intent to Comply (NIC) requirements finalized in the ``fast-track''
rule of June 19, 1998. (See 63 FR at 33782.)
The NIC requires you to prepare an implementation plan that
identifies your intent to comply with the final rule and the basic
means by which you intend to do so. That plan must be released to the
public in a public forum and formally submitted to the Agency. The
notice of intent certifies your intentions--either to comply or not to
comply--and identifies milestone dates that measure your progress
toward compliance with the final emission standards or your progress
toward closure, if you choose not to comply. Prior to submitting the
NIC to the regulatory Agency, you must provide notice of a public
meeting and conduct an informal public meeting with your community to
discuss the draft NIC and your plans for achieving compliance with the
new standards.
We have redesignated the existing NIC provisions to meld them into
the appropriate sections of subpart EEE. We have also revised the
regulatory language to include references to the new provisions
promulgated today. See Part Six, Section IX of today's preamble.
IV. What Are the Requirements for Documentation of Compliance?
A. What Is the Purpose of the Documentation of Compliance?
The purpose of the Documentation of Compliance 179 (DOC)
is for you to certify by the compliance date that: (1) You have made a
good faith effort to establish limits on the operating parameters
specified in Sec. 63.1209 that you believe ensure compliance with the
emissions standards; (2) required continuous monitoring systems are
operational and meet specifications; and (3) you are in compliance with
the other operating requirements. See Sec. 63.1211(d). This is
necessary because all sources must be in compliance by the compliance
date even though they are not required to demonstrate compliance,
through performance testing, until 180 days after the compliance date.
To fulfill the requirements of the DOC, you must place it in the
operating record by the compliance date, September 30, 2002. (See
compliance dates in Section II above.) Information that must be in the
DOC includes all information necessary to determine your compliance
status (e.g., operating parameter limits; functioning automatic waste
feed cutoff system). All operating limits identified in the DOC are
enforceable limits. However, if these limits are determined, after the
initial comprehensive performance test, to have been inadequate to
ensure compliance with the MACT standards, you will not be deemed to be
out of compliance with the MACT emissions standards, if you complied
with the DOC limits.180
---------------------------------------------------------------------------
\179\ We renamed the proposed Precertification of Compliance as
the Documentation of Compliance to avoid any confusion with the RCRA
requirement of similar name.
\180\ Once you determine that you failed to demonstrate
compliance during the performance test, all monitoring data is
subject to potential case-by-case use as credible evidence to show
noncompliance following that determination. Therefore, you could
potentially find yourself in noncompliance for the period which the
DOC limits were in effect following that determination, but before
submission of the NOC.
---------------------------------------------------------------------------
B. What Is the Rationale for the DOC?
In the May 1997 NODA, we discussed the concept of the
precertification of compliance (Pre-COC). The discussion required
sources to precertify their compliance status on the compliance date by
requiring them to submit a notification to the appropriate regulatory
agency. This notification would detail the operating limits under which
a source would operate during the period following the compliance date,
but before submittal of the initial comprehensive performance test
results in the Notification of Compliance.
Commenters question this provision since the Pre-COC operating
limits would be effective only for the 270 days following the
compliance date. Other commenters support the Pre-COC requirements
provided the process is focused, straightforward, and limited to the
minimum operating parameters necessary to document compliance.
Commenters also stress that the Agency needed to specify the
requirements of the prenotification, using appropriate sections of 40
CFR 266.103(b) and Section 63.9 when developing the specific regulatory
requirements. In addition, commenters suggest that the Agency clarify
the relationship between the Pre-COC and the title V permit, and
indicate how or if the Pre-COC operating limits would be placed in the
title V permit.
Other commenters state that the rationale underlying the Pre-COC is
faulty because sources would remain subject to the RCRA permit
conditions until the NOC is submitted or until the title V permit is
issued, which was our proposed approach to permitting at that time.
Therefore, the Agency's concern that sources could be between
regulatory regimes is not relevant. Commenters also state that Pre-COC
requirements would be resource intensive and a needless exercise that
diverted time and attention from preparing to come into compliance with
MACT standards.
The DOC requirements and process adopted today provide the Agency
and public a sound measure of assurance
[[Page 52910]]
that, on the compliance date, combustion sources are operated within
limits that should ensure compliance with the MACT standards and
protection to human health and the environment. We agree that operating
limits in the DOC will be in effect only for a short period of time and
that affected sources will not be between regulatory regimes at any
time. Given the relatively short period of time the DOC conditions will
be in effect, however, we chose for the final rule not to specify
whether the conditions need to be incorporated into a title V permit
and do not require the permitting authority to do so. We provide
flexibility for agencies implementing title V programs to determine the
appropriate level of detail to include in the permit, thereby allowing
them to minimize the potential need for permit revisions. In addition,
we do not require that the DOC be submitted to the permitting
authority, to avoid burdening the permitting agency with unnecessary
paper work during the period that they are reviewing site-specific
performance test plans. In today's rule, we better define the period
during which the DOC applies by specifying that the DOC is superseded
by the NOC upon the postmark date for submittal of the NOC. Once you
mail the NOC, its contents become enforceable unless and until
superseded by test results submitted within 270 days following
subsequent performance testing. This approach provides clarity on when
the NOC supersedes the DOC.
C. What Must Be in the DOC?
You must complete your site-specific DOC and place it in your
operating record by the compliance date. The DOC must contain all of
the information necessary to determine your compliance status during
periods of operation including all operating parameter limits. You must
identify the DOC operating limits through the use of available data and
information. If your unit requires modification or upgrades to achieve
compliance with the emission standards, you can base this judgment on
results of shakedown tests and/or manufacturers assertions or
specifications. If your unit does not require modifications or upgrades
to meet the emission standards of today's rule, you can develop the
operating limits through analysis of previous performance tests or
knowledge of the performance capabilities of your control equipment.
Your limitations on operating parameters must be based on an
engineering evaluation prepared under your direction or supervision in
accordance with a system designed. This evaluation must ensure that
qualified personnel properly gathered and evaluated the information and
supporting documentation, and considering at a minimum the design,
operation, and maintenance characteristics of the combustor and
emissions control equipment, the types, quantities, and characteristics
of feedstreams, and available emissions data.
This requirement should not involve a significant effort because
your decisions on whether to upgrade and modify your units will be
based on the current performance of your control equipment and the
performance capabilities of new equipment you purchase. We expect that,
by the compliance date, you will have an adequate understanding of your
unit's capabilities, given the three years to develop this expertise.
Therefore, by the compliance date, you are expected to identify
operating limits that are based on technical or engineering judgment
that should ensure compliance with the emission standards.
V. What Are the Requirements for MACT Performance Testing?
A. What Are the Compliance Testing Requirements?
Today's final rule requires two types of performance testing to
demonstrate compliance with the MACT emission standards: Comprehensive
and confirmatory performance testing. See Sec. 63.1207. The purpose of
comprehensive performance testing is to demonstrate compliance and
establish operating parameter limits. You must conduct your initial
comprehensive performance tests by 180 days (i.e., approximately six
months) after your compliance date. You must submit results within 90
days (i.e., approximately 3 months) of completing your comprehensive
performance test. If you fail a comprehensive performance test, you
must stop burning hazardous waste until you can demonstrate compliance
with today's MACT standards. Comprehensive performance testing must be
repeated at least every five years, but may be required more frequently
if you change operations or fail a confirmatory performance test.
The purpose of confirmatory performance tests is to confirm
compliance with the dioxin/furan emission standard during normal
operations. You must conduct confirmatory performance tests midway
between comprehensive performance tests. Confirmatory performance tests
may be conducted under normal operating conditions. If you fail a
confirmatory performance test, you must stop burning hazardous waste
until you demonstrate compliance with the dioxin/furan standard by
conducting a comprehensive performance test to establish revised
operating parameter limits.
The specific requirements and procedures for these two performance
tests are discussed later in this section. In addition, this section
discusses the interaction between the RCRA permitting process and the
MACT performance test.
1. What Are the Testing and Notification of Compliance Schedules?
Section 63.7 of the CAA regulations contains the general
requirements for testing and notification of compliance. In today's
rule, we adopt some Sec. 63.7 requirements without change and adopt
others with modifications. As summarized earlier, you must commence
your initial comprehensive performance test within 180 days after your
compliance date, consistent with the general Sec. 63.7 requirements.
You must complete testing within 60 days of commencement, unless a time
extension is granted. This requirement is necessary because testing and
notification of compliance deadlines are based on the date of
commencement or completion of testing. Those deadlines could be
meaningless if a source had unlimited time to complete testing.
Although we propose to require testing to be completed within 30 days
of commencement, commenters state that unforeseen events could occur
(e.g., system breakdown causing extensive repairs; loss of samples from
breakage of equipment or other causes requiring additional test runs)
that could extend the testing period beyond normal time frames. We
concur, and provide for a 60-day test period as well as a case-by-case
time extension that may be granted by permit officials if warranted
because of problems beyond our control.
Additionally, you must submit comprehensive performance test
results to the Administrator within 90 days of test completion, unless
a time extension is granted. We are allowing an additional 30 days for
result submittal beyond the Secs. 63.7(g) and 63.8(e)(5) 60-day
deadlines because the dioxin/furan analyses required in today's rule
may take this additional time to complete. We also are including a
provision for a case-by-case time extension in the final rule because
commenters express concern that the limited laboratory facilities
nationwide may be taxed by the need to handle analyses simultaneously
for many hazardous
[[Page 52911]]
waste combustors. The available analytical services may not be able to
handle the workload, that could cause some sources to miss the proposed
90-day deadline. We concur with commenters' concerns and have added a
provision to allow permit officials to grant a case-by-case time
extension, if warranted.
Test results must be submitted as part of the notification of
compliance (NOC) submitted to the Administrator under Secs. 63.1207(j)
and 63.1210(d) documenting compliance with the emission standards and
continuous monitoring system requirements, and identifying applicable
operating parameter limits. These provisions are similar to
Secs. 63.7(g) and 63.8(e)(5), except that the NOC must be postmarked by
the 90th day following the completion of performance testing and the
continuous monitoring system performance evaluation.
Overall, the initial NOC must be postmarked within 270 days (i.e.,
approximately nine months) after your compliance date. You must
initiate subsequent comprehensive performance tests within 60 months
(i.e., five years) of initiating your initial comprehensive performance
test. You must submit subsequent NOCs, containing test results, within
90 days after the completion of subsequent tests.
The rule allows you to initiate subsequent tests any time up to 30
days after the deadline for the subsequent performance test. Thus, you
can modify the combustor or add new emission control equipment at any
time and conduct new performance testing to document compliance with
the emission standards. In addition, this testing window allows you to
plan to commence testing well in advance of the deadline to address
unforseen events that could delay testing.181 This testing
window applies to both comprehensive performance tests and confirmatory
performance tests. For example, if the deadline for your second
comprehensive performance test is January 10, 2008, you may commence
the test at any time after completing the initial comprehensive
performance test but not later than February 10, 2008. The deadline for
subsequent comprehensive and confirmatory performance tests are based
on the commencement date of the previous comprehensive performance
test.
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\181\ We note that a case-by-case time extension for
commencement of subsequent performance testing is also provided
under Sec. 63.1207(i).
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2. What Are the Procedures for Review and Approval of Test Plans and
Requirements for Notification of Testing?
In the April 1996 NPRM, we proposed in Sec. 63.7(b)(1) to require
submittal of a ``notification of performance test'' to the
Administrator 60 days prior to the planned test date. This notification
included the site-specific test plan itself for review and approval by
the Administrator (Sec. 63.8(e)(3)). In the May 1997 NODA, to ensure
coordination of destruction removal efficiency (DRE) and MACT
performance testing, we considered requiring you to submit the test
plan one year rather than 60 days prior to the scheduled test date to
allow the regulatory official additional time to consider DRE testing
in context with MACT comprehensive performance testing. This one-year
test review period would only have applied to sources required to
perform a DRE test.
In today's final rule, we maintain the requirement for you to
submit the test plan one year prior to the scheduled test date, but
apply that requirement to all sources, not just those performing a DRE
test. After consideration of comments (described below), we determined
that this one-year period is needed to provide regulatory officials
sufficient time (i.e., nine months) to review and approve or notify you
of intent to disapprove the plan. Nine months is needed for the review
for all sources given the amount of technical information that would be
included in the test plan, and would also allow time to assess whether
a source is required to perform a DRE test (see Part IV, Section IV,
for discussion of DRE testing requirements; see also
Sec. 63.1206(b)(8)). During this nine-month period, the regulatory
officials will review your test plan and determine if it is adequate to
demonstrate compliance with the emission standards and establish
operating requirements.
After submittal of the test plan, review and approval or
notification of intent to deny approval of the test plan will follow
the requirements of Sec. 63.7(c)(3). That section provides procedures
for you to provide additional information before final action on the
plan. It also requires you to comply with the testing schedule even if
permit officials have not approved your test plan. The only exception
to this requirement is if you proposed to use alternative test methods
to those specified in the rule. In that case, you may not conduct the
performance test until the test plan is approved, and you have 60 days
after approval to conduct the test.
Several commenters suggest that it would be difficult for permit
officials to review and approve test plans within the nine-month window
given that many test plans may be submitted at about the same time.
They cite experiences under RCRA trial burn plan approvals where permit
officials have taken much longer than nine months to approve a plan,
and have requested that the final rule allow for a longer review
period. Commenters are concerned with the consequences of being
required to conduct the performance test even though permit officials
may not have had time to approve the test plan. They recite various
concerns that permit officials may at a later date determine that the
performance test was inadequate and require retesting. Commenters
suggest that the rule establish the date for the initial comprehensive
performance test as 60 days following approval of the test plan,
whenever that may occur, thus extending the deadline for the
performance test indefinitely from the current requirement of six
months after the compliance date.
We maintain that the nine-month review period is appropriate for
several reasons. First, we are unwilling to build into the regulations
an indefinite period for review. This would have the potential to delay
implementation of the MACT emission standards without any clear and
compelling reason to do so.
Second, the RCRA experience with protracted approval schedules,
sometimes over a decade ago, is not applicable or analogous to the MACT
situation. Under the RCRA regulatory regime, particularly at the early
stages, there were few incentives for either permit officials or owners
or operators to expeditiously negotiate acceptable test plans. No
statutory deadlines existed for a compliance date, and existing
facilities operated under interim status (a type of grand fathering
tantamount to a permit). This interim status scheme placed at least
some controls on hazardous waste combustors during the permit
application and trial burn test plan review periods. As a result,
regulatory officials could take significant amounts of time to address
what was then a new type of approval, that for trial burn testing to
meet RCRA final permit standards.
Under MACT, the situation today is quite different. In light of the
statutory compliance date of 3 years and the existing regulatory
framework, sources know as of today's final rule that they need to
respond promptly and effectively to permit officials' concerns about
the test plan because the performance test must be conducted
[[Page 52912]]
within six months after the compliance date whether or not the test
plan is approved. And they have at least two years to prepare and
submit these plans, and to work with regulatory officials even before
doing so. For their part, permit officials recognize that they have the
responsibility to review and approve the plan or notify the source of
their intent to deny approval within the nine-month window given that
the source must proceed with expensive testing on a fixed deadline
whether or not the plan is approved. To the extent regulatory officials
anticipate that many test plans will be submitted at about the same
time, the agencies have at least two years to figure out ways to
accommodate this scenario from a resource and a prioritization
standpoint. If permit officials nevertheless fail to act within the
nine-month review and approval period, a source could argue that this
failure is tacit approval of the plan and that later ``second-
guessing'' is not allowable. This should be a very strong incentive for
regulatory officials to act within the nine months, especially with a
two-year lead time to avoid this type of situation
In addition, the RCRA experience is not a particularly good
harbinger of the future MACT test plan approval, as commenters suggest,
because most sources will have already completed trial burn testing
under RCRA. Thus, both the regulatory agencies and the facilities have
been through one round of test plan submittal, review, and approval for
their combustion units. Given that MACT testing is very similar to RCRA
testing, approved RCRA test protocols can likely be modified as
necessary to accommodate any changes required under the MACT rule.
Although some of these changes may be significant, we expect that many
will not be. For example, RCRA trial burn testing always included DRE
testing. Under the MACT rule, DRE testing will not be required for most
sources. And for sources where DRE testing is required under MACT, most
will have already been through a RCRA approval of the DRE test
protocol, which should substantially simplify the process under MACT.
The third reason that we maintain the nine-month review and
approval window is appropriate is that discussions with several states
leads us to conclude that they are prepared to meet their obligations
under this provision. This is a highly significant indicator that the
nine-month review and approval period is a reasonable period of time,
particularly since all permitting agencies have at least two years to
plan for submittal of test plans from the existing facilities in their
jurisdictions.
In summary, sound reasons exist to expect that today's final rule
provides sufficient time for the submittal, review, and approval of
test plans. Furthermore, clear incentives exist for both owners and
operators and permit officials to work together expeditiously to ensure
that an approval or notice of intent to disapprove the test plan can be
provided within the nine-months allotted.
On a separate issue, we also retain, in today's final rule, the 60-
day time frame and requirements of Sec. 63.7(b)(1) for submittal of the
notification of performance test. Additionally, the final rule
continues to provide an opportunity for, but does not require, the
regulatory agency to review and oversee testing.
3. What Is the Provision for Time Extensions for Subsequent Performance
Tests?
The Administrator may grant up to a one year time extension for any
performance test subsequent to the initial comprehensive performance
test. This enables you to consolidate MACT performance testing and any
other emission testing required for issuance or reissuance of Federal/
State permits.182
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\182\ In addition, this provision also may assist you when
unforseen events beyond your control (e.g., power outage, natural
disaster) prevent you from meeting the testing deadline.
---------------------------------------------------------------------------
At the time of proposal, we were concerned about how to allow
coordination of MACT performance tests and RCRA trial burns. As
discussed elsewhere, the RCRA trial burn is superseded by MACT
performance testing. However, a one-year time extension may still be
necessary for you to coordinate performance of a RCRA risk burn. In
addition, commenters state that there may be additional reasons to
grant extension requests (e.g. some TSCA-regulated hazardous waste
combustors may be required to perform stack tests beyond those required
by MACT). Furthermore, some sources may have to comply with state
programs requiring RCRA trial burn testing. To address these
situations, to promote coordinated testing, and to avoid unnecessary
source costs, the final rule allows up to a one-year time extension for
the performance test.
When performance tests and other emission tests are consolidated,
the deadline dates for subsequent comprehensive performance tests are
adjusted correspondingly. For example, if the deadline for your
confirmatory performance test is January 1 and your state-required
trial burn is scheduled for September 1 of the same year, you can apply
to adjust the deadline for the confirmatory performance test to
September 1. If granted, this also would delay by a corresponding time
period the deadline dates for subsequent comprehensive performance
tests.
The procedures for granting or denying a time extension for
subsequent performance tests are the same as those found in
Sec. 63.6(i), which allow the Administrator to grant sources up to one
additional year to comply with standards.183 These are also
the same procedures apply to a request for a time extension for the
initial NOC.
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\183\ Note, however, that Sec. 63.6(i) applies to an entirely
different situation: extension of time for initial compliance with
the standards, not subsequent performance testing.
---------------------------------------------------------------------------
4. What Are the Provisions for Waiving Operating Parameter Limits
During Subsequent Performance Tests?
Operating parameter limits are automatically waived during
subsequent comprehensive performance tests under an approved
performance test plan. See Sec. 63.1207(h). This waiver applies only
for the duration of the comprehensive performance test and during
pretesting for an aggregate period up to 720 hours of operation. You
are still required to be in compliance with MACT emissions standards at
all times during these tests, however.
In the April 1996 NPRM, we proposed to allow the burning of
hazardous waste only under the operating limits established during the
previous comprehensive performance test (to ensure compliance with
emission standards not monitored with a continuous emissions monitoring
system). Two types of waivers from this requirement would have been
provided during subsequent comprehensive performance tests: (1) An
automatic waiver to exceed current operating limits up to 5 percent;
and (2) a waiver that the Administrator may grant if warranted to allow
the source to exceed the current operating limits without restriction.
We proposed an automatic waiver because, without the waiver, the
operating limits would become more and more stringent with subsequent
comprehensive performance tests. This is because sources would be
required to operate within the more stringent conditions to ensure that
they did not exceed a current operating limit. This would result in a
shrinking operating envelope over time.
A number of commenters question the comprehensive performance
test's 5%
[[Page 52913]]
limit over existing permit conditions. Some commenters state that the
EPA should not limit a facility's operating envelope from test to test
based on operating conditions established during the previous test. The
operator should be free to set any conditions for the comprehensive
performance test, short of what the regulator deems to pose a short-
term environmental or health threat or inadequate to ensure compliance
with an emission standard. Commenters also state that the requirement
that the facility accept the more stringent of the existing 5% limit or
the test result will inevitably result in the ratcheting down of limits
over time. Since certain conditions have much greater variation than 5%
over a limit, sufficient variability must be allowed so the operator
can run a test under the conditions it wishes to use as the basis for
worst case operation.
We agree that a waiver is necessary to avoid ratcheting down the
operating limits in subsequent tests. Further, in view of the natural
variability in hazardous waste combustor operations, a 5% waiver may be
insufficient. Because you are required to comply with the emission
standards, there does not appear to be any reason to establish national
restrictions on operations during subsequent performance tests.
Therefore, the final rule allows a waiver from previously established
operating parameter limits, as long as you comply with MACT emission
standards and are operating under an approved comprehensive performance
test plan. Operating parameter limits will be reset based on the new
tests. Furthermore, the permitting authority will review and has the
opportunity to disapprove any proposed test conditions which may result
in an exceedance of an emission standard.
B. What Is the Purpose of Comprehensive Performance Testing?
The purposes of the comprehensive performance test are to: (1)
Demonstrate compliance with the continuous emissions monitoring
systems-monitored emission standards for carbon monoxide and
hydrocarbons; (2) conduct manual stack sampling to demonstrate
compliance with the emission standards for pollutants that are not
monitored with a continuous emissions monitoring system (e.g., dioxin/
furan, particulate matter, DRE, mercury, semivolatile metal, low
volatile metal, hydrochloric acid/chlorine gas); (3) establish limits
on the operating parameters required by Sec. 63.1209 (Monitoring
Requirements) to ensure compliance is maintained with those emission
standards for which a continuous emissions monitoring system is not
used for compliance monitoring; and (4) demonstrate that performance of
each continuous monitoring system is consistent with applicable
requirements and the quality assurance plan. In general, the
comprehensive performance test is similar in purpose to the RCRA trial
burn and BIF interim status compliance test, but with relatively less
Agency oversight and a higher degree of self-implementation, as
discussed below.
The basic framework for comprehensive performance testing is set
forth in the existing general requirements of subpart A, part 63.
Therefore, for convenience of the reader, we will review key elements
of those regulations and highlight any modifications made specifically
for hazardous waste combustors.
1. What Is the Rationale for the Five Year Testing Frequency?
As discussed earlier, you must perform comprehensive performance
testing every five years. We require periodic comprehensive performance
testing because we are concerned that long-term stress to the critical
components of a source (e.g., firing systems, emission control
equipment) could adversely affect emissions.
In the April 1996 NPRM, we proposed that large sources (i.e., those
with a stack gas flow rate greater than 23,127 acfm) and sources that
accept off-site wastes would be required to perform comprehensive
performance testing every three years. We also proposed that small, on-
site sources perform comprehensive performance testing every five years
unless the Administrator determined otherwise on a case-specific basis.
Commenters suggest that the proposed three year testing frequency is
too restrictive. They said that test plan approval time, bad weather,
mechanical failure, and the testing itself combine to make the proposed
test frequency too tight for tests of this magnitude.
We agree that, due to the magnitude of the comprehensive
performance test, a more appropriate testing schedule is required.
Therefore, we adopt a comprehensive performance testing frequency of
every five years for small and large sources. In addition, this
comprehensive performance testing schedule should correspond to the
renewal of the title V permit. More frequent comprehensive performance
testing is required, however, if there is a change in design,
operation, or maintenance that may adversely affect compliance. See
Sec. 63.1206(b)(6).
2. What Operations Are Allowed During a Comprehensive Performance Test?
Because day-to-day limits are established for operating parameters
during the comprehensive performance test, we allow operation during
the performance test as necessary provided the unit complies with the
emission standards. Accordingly, you can spike feedstreams with metals
or chlorine, for example, to ensure that the feedrate limits are
sufficient to accommodate normal operations while allowing some
flexibility to feed higher rates. See Part Four, Section I. B. above
for further discussion of normal operations. We note that this differs
from Sec. 63.7(e) which requires performance testing under ``normal''
operating conditions. See Sec. 63.1207(g).
Most commenters agree that the comprehensive performance test
should be conducted under extreme conditions at the edge of the
operating envelope. Commenters point out that they needed to operate in
this mode to establish operating parameter limits to cover all possible
normal operating emissions values. Commenters also state that
feedstreams may need to be spiked with metals or chlorine to ensure
limits high enough to allow operational flexibility. We agree that
these modes of operation are needed to establish operating parameter
limits that cover all possible normal operating emissions
values.184 There is precedent for this approach in current
rules regulating hazardous waste combustors (e.g., the RCRA incinerator
and BIF rules).
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\184\ Allowing sources to operate during MACT comprehensive
performance testing under the worst-case conditions, as allowed
during RCRA compliance testing, rather than under normal conditions
as provided by Sec. 63.7(e) for other MACT sources, ensures that the
emissions standards do not restrict hazardous waste combustors using
MACT control to operations resulting in emissions that are lower
than normal. Therefore, allowing performance testing on a worst-case
basis provides that the MACT emission standards are achievable in
practice by sources using MACT control.
---------------------------------------------------------------------------
In addition, two or more modes of operation may be identified, for
which separate performance tests must be conducted and separate limits
on operating conditions must be established. If you identify two modes
of operation for your source, you must note in the operating record
which mode you are operating under at all times. For example, two modes
of operation must be identified for a cement kiln that routes kiln off-
gas through the raw meal mill to help dry the raw meal. When the raw
meal mill is not operating (perhaps 15% of the time), the kiln gas
bypasses the raw meal mill. Emissions of particulate matter and other
hazardous air
[[Page 52914]]
pollutants or surrogates may vary substantially depending on whether
the kiln gas bypasses the raw meal mill.
As discussed below for confirmatory testing, when conducting the
comprehensive performance test, you also must operate under
representative conditions for specified parameters that may affect
dioxin/furan emissions. These conditions must ensure that emissions are
representative of normal operating conditions. Also, when demonstrating
compliance with the particulate matter, semivolatile metal, and low
volatile metal emission standards, when using manual stack sampling,
and when demonstrating compliance with the dioxin/furan and mercury
emission standards using carbon injection or carbon bed, you must
operate under representative conditions for the cleaning cycle of the
particulate matter control device. This is because particulate matter
emissions increase momentarily during cleaning cycles and can affect
emissions of these pollutants.
3. What Is the Consequence of Failing a Comprehensive Performance Test?
If you determine that you failed any emission standard during the
performance test based on: (1) Continuous emissions monitoring systems
recordings; (2) results of analysis of samples taken during manual
stack sampling; or (3) results of the continuous emissions monitoring
systems performance evaluation, you must immediately stop burning
hazardous waste. However, if you conduct the comprehensive performance
test under two or more modes of operation, and you meet the emission
standards when operating under one or more modes of operation, you are
allowed to continue burning under the mode of operation for which the
standards were met.
If you fail one or more emission standards during all modes of
operation tested, you may burn hazardous waste only for a total of 720
hours and only for the purposes of pretesting (i.e., informal testing
to determine if the combustor can meet the standards operating under
modified conditions) or comprehensive performance testing under
modified conditions. The same standards apply for the retest as applied
for the original test. These conditions apply when you fail the initial
or subsequent comprehensive performance test.
A number of commenters suggest that the 720 operating hours allowed
after a failed performance test should be renewable, as they are under
existing incinerator and BIF rules. We are persuaded by the commenters'
rationale and will adopt this practice in today's rule. The final rule
allows the 720 hours of operation following a failed performance test
to be renewed as often as the Administrator deems reasonable. We note
that hazardous waste combustors are currently subject to virtually
these same requirements under RCRA rules.
If you fail a comprehensive performance test, you must still submit
a NOC as required indicating the failure. We want to ensure that the
regulatory authorities are fully aware of a failure and the need for
the facility to initiate retesting.
We do not specifically address other consequences of failing the
comprehensive performance test in the regulatory language. We will
instead rely on the regulating agency's enforcement policy to govern
the type of enforcement response at a facility that exceeds an emission
standard, fails to ensure compliance with the standards, or fails to
meet a compliance deadline.
C. What Is the Rationale for Confirmatory Performance Testing?
Confirmatory performance testing for dioxin/furan is required
midway between the cycle required for comprehensive performance testing
to ensure continued compliance with the emission standard. We require
such testing only for dioxin/furan given: (1) The health risks
potentially posed by dioxin/furan emissions; (2) the lack of a
continuous emissions monitoring system for dioxin/furan; (3) the lack
of a material that directly and unambiguously relates to dioxin/furan
emissions which could be monitored continuously by means of feedrate
control (as opposed to, for example, metals feedrates, which directly
relate to metals emissions); and (4) wear and tear on the equipment,
including any emission control equipment, which over time could result
in an increase in dioxin/furan emissions even though the source stays
in compliance with applicable operating limits.
Although emissions of dioxins/furans appear to be primarily a
function of whether particulate matter is retained in post-combustion
regions of the combustor (e.g., in an electrostatic precipitator or
fabric filter, or on boiler tubes) in the temperature range that
enhances dioxin/furan formation, the factors that affect dioxin/furan
formation are imperfectly understood. Certain materials seem to inhibit
formation while others seem to enhance formation. Some materials seem
to be precursors (e.g., PCBs). Changes in the residence time of
particulate matter in a control device may affect the degree of
chlorination of dioxins/furans, and thus the toxicity equivalents of
the dioxins/furans. Given these uncertainties, the health risks posed
by dioxins/furans, and the relatively low cost of dioxin/furan testing,
it appears prudent to require confirmatory testing to determine if
changes in feedstocks or operations that are not limited by the MACT
rule may have increased dioxin/furan emissions to levels exceeding the
standard. We also note that confirmatory dioxin/furan testing is
required for municipal waste combustors (60 FR at 65402 (December 19,
1995)).
Confirmatory testing differs from comprehensive testing, however,
in that you are required to operate under normal, representative
conditions during confirmatory testing. This will reduce the cost of
the test, while providing the essential information, because you will
not have to establish new operating limits based on the confirmatory
test.
1. Do the Comprehensive Testing Requirements Apply to Confirmatory
Testing?
The following comprehensive performance testing requirements
discussed above also apply to confirmatory testing: Agency oversight,
notification of performance test, notification of compliance, time
extensions, and failure to submit a timely notice of compliance.
However, we modify some of the comprehensive test requirement for
confirmatory tests, as discussed below.
2. What Is the Testing Frequency for Confirmatory Testing?
You are required to conduct confirmatory performance testing 30
months (i.e., 2.5 years) after the previous comprehensive performance
test. The same two-month testing window, applicable for comprehensive
tests, also applies to confirmatory tests.
Several commenters state that the proposed schedule for
confirmatory tests is too frequent. The April 1996 NPRM would have
required large and off-site sources to conduct confirmatory performance
testing 18 months after the previous comprehensive performance test.
Small, on-site sources would have been required to conduct the testing
30 months after the previous comprehensive performance test. One
commenter suggests that the frequency should be at multiples of 12
months to avoid seasonal weather problems in many locations. Other
commenters state that EPA's justification for confirmatory tests is not
supported by evidence
[[Page 52915]]
showing increased emissions due to equipment aging and that the
performance of combustion practice parameters is already assured
through continuous monitoring systems.
We agree that due to the magnitude and expense of the test, a more
appropriate testing schedule would be every 2.5 years, mid-way between
the comprehensive performance test cycle. In addition, we agree that
testing in certain locations at certain times of the year (e.g.,
northern states in the winter) can be undesirable. Although possible,
it would add to the difficulty and expense of the testing. As
previously discussed, sources can request a time extension to allow for
a more appropriate testing season. However, the regulatory date for
confirmatory testing remains midcycle to the comprehensive performance
testing.
3. What Operations Are Allowed During Confirmatory Performance Testing?
As proposed, you are required to operate under normal conditions
during confirmatory performance testing. Normal operating conditions
are defined as operations during which: (1) The continuous emissions
monitoring systems that measure parameters that could relate to dioxin/
furan emissions--carbon monoxide or hydrocarbons--are recording
emission levels within the range of the average value for each
continuous emissions monitoring system (the sum of all one-minute
averages, divided by the number of one minute averages) over the
previous 12 months to the maximum allowed; (2) each operating parameter
limit established to maintain compliance with the dioxin/furan emission
standard (see discussion in Part Five, Section VI.D.1 below and
Sec. 63.1209(k)) is held within the range of the average values over
the previous 12 months and the maximum or minimums, as appropriate,
that are allowed; (3) chlorine feedrates are set at normal or greater;
and (4) when using carbon injection or carbon bed, the test is
conducted under representative conditions for the cleaning cycle of the
particulate matter control device. See Sec. 63.1207(g)(2).
We define normal operating conditions in this manner because,
otherwise, sources could elect to limit levels of the regulated dioxin/
furan operating parameters (e.g., hazardous waste feedrate, combustion
chamber temperature, temperature at the inlet to the dry particulate
matter control device) to ensure minimum emissions. Thus, without
specifying what constitutes normal conditions, the confirmatory test
could be meaningless. On the other hand, the definition of normal
conditions is broad enough to allow adequate flexibility in operations
during the test. The confirmatory test confirms that your under day-to-
day operations are meeting the dioxin/furan standard. Thus, the
confirmatory test differs from the comprehensive performance test in
which you may choose to extend to the edge of the operating envelope to
establish operating parameters.
The April 1996 NPRM would have required normal operating conditions
for particulate matter continuous emissions monitoring systems. For the
final rule, particulate matter levels are limited during confirmatory
testing to ensure normal operations only when your source is equipped
with carbon injection or carbon bed for dioxin/furan emissions control
(see dioxin/furan operating limits discussion below).
The April 1996 NPRM also would have required you to operate under
representative conditions for types of organic compounds in the waste
(e.g., aromatics, aliphatics, nitrogen content, halogen/carbon ratio,
oxygen/carbon ratio) and volatility of wastes when demonstrating
compliance with the dioxin/furan emission standard. Several commenters
object to this requirement. We agree that restrictions on these organic
compounds in the waste are redundant and not necessary to assure good
combustion. In addition, the requirement would be impracticable because
in most cases measured data would not be available on these parameters.
Therefore, the final rule does not require ``representative'' wastes
with regard to these organic compounds for confirmatory testing.
It is prudent to require that chlorine be fed at normal levels or
greater during the dioxin/furan confirmatory performance test. Although
most studies show poor statistical correlation between dioxin/furan
emissions and chlorine feedrate, some practical considerations are
important. Chlorinated dioxin/furan obviously contain chlorine and some
level of chlorine is necessary for its formation. During the
confirmatory testing for dioxin/furan, we want you to operate your
combustor under normal conditions relative to factors that can affect
emissions of dioxin/furan. Therefore, you must feed chlorine at normal
or greater levels given the potential for chlorine feedrates to affect
dioxin/furan emissions. For the confirmatory performance test, normal
is defined as the average chlorine fed over the previous 12 months. If
you have established a maximum chlorine value for metals or total
chlorine compliance in your previous comprehensive performance test,
then that value can be used in the confirmatory test.
Several commenters suggest that when defining normal operation, a
provision should be made to exclude inappropriate data, such as those
occurring during instrument malfunction, at unit down time, or during
instrument zero/calibration adjustment. The April 1996 NPRM did not
allow for any data to be excluded. To define ``normal'' operation, we
agree it is reasonable to exclude inappropriate data. For the final
rule, calibration data, malfunction data, and data obtained when not
burning hazardous waste do not fall into the definition of ``normal''
operation.
4. What Are the Consequences of Failing a Confirmatory Performance
Test?
If you determine that you failed the dioxin/furan emission standard
based on results of analysis of samples taken during manual stack
sampling, you must immediately stop burning hazardous waste. You must
then modify the design or operation of the unit, conduct a new
comprehensive performance test to demonstrate compliance with the
dioxin/furan emission standard (and other standards if the changes
could adversely affect compliance with those standards), and establish
new operating parameter limits. Further, prior to submitting a NOC
based on the new comprehensive performance test, you can burn hazardous
waste only for a total of 720 hours (renewable based on the discretion
of the Administrator) and only for purposes of pretesting or
comprehensive performance testing. These conditions apply when you fail
the initial or any periodic confirmatory performance test.
However, if you conduct the comprehensive performance test under
two or more modes of operation, and meet the dioxin/furan emission
standards during confirmatory testing when operating under one or more
modes of operation, you may continue burning under the modes of
operation for which you meet the standards.
Other than stopping burning of hazardous waste, we do not
specifically address the consequences of failing the confirmatory
performance test in the regulatory language but will instead rely on
the regulating agency's enforcement policy to govern the type of
enforcement response at a facility that exceeds an emission standard,
fails to ensure compliance with the standards, or fails to meet a
compliance deadline. This approach is consistent with the way
[[Page 52916]]
other MACT standards are implemented.
Some commenters suggest that the requirement to stop burning waste
after a failed confirmatory test is overly harsh. They suggest that
temporarily restricted burning should be allowed, conservative enough
to insure compliance, while a permanent solution is developed. We
continue to believe that a source should stop burning hazardous waste
until it reestablishes operating parameter limits that ensure
compliance with the dioxin/furan emission standard. We note that
hazardous waste combustors are currently subject to virtually these
same requirements under RCRA rules.
D. What Is the Relationship Between the Risk Burn and Comprehensive
Performance Test?
1. Is Coordinated Testing Allowed?
Traditionally, a RCRA trial burn serves three primary functions:
(1) Demonstration of compliance with performance standards such as
destruction and removal efficiency; (2) determination of operating
conditions that assure the hazardous waste combustor can meet
applicable performance standards; and (3) collection of emissions data
for incorporation into a SSRA that, subsequently, is used to establish
risk-based permit conditions where necessary.185 Today's
rulemaking transfers the first two functions of a RCRA trial burn from
the RCRA program to the CAA program. The responsibility for collecting
emissions data needed to perform a SSRA is not transferred because
SSRAs are exclusively a RCRA matter.
---------------------------------------------------------------------------
\185\ Under 40 CFR 270.10(k), which is the RCRA Part B
information requirement that supports implementation of the RCRA
omnibus permitting authority, a regulatory authority may require a
RCRA permittee or an applicant to submit information to establish
permit conditions as necessary to protect human health and the
environment. Under this authority, risk burns and SSRAs may be
required.
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Generally speaking, the type of emissions data needed to conduct a
SSRA includes concentration and gas flow rate data for dioxin/furans,
nondioxin/furan organics, metals, hydrogen chloride, and chlorine gas.
Additionally, particle-size distribution data are normally needed for
the air modeling component of the SSRA. We have recently published
guidance on risk burns and the data to be collected. See USEPA, ``Human
Health Risk Assessment Protocol for Hazardous Waste Combustion
Facilities'' External Peer Review Draft, EPA-530-D-98-001A, B & C and
USEPA, ``Guidance on Collection of Emissions Data to Support Site-
Specific Risk Assessments at Hazardous Waste Combustion Facilities,''
EPA 530-D-98-002, August 1998.
A large number of hazardous waste combustors subject to today's
rule will have completed a RCRA trial burn and SSRA emissions testing
prior to the date of the MACT comprehensive performance test. There may
exist, however, some facilities for which this is not the case. For
these facilities, the Agency proposed, in both the April 1996 NPRM and
the May 1997 NODA, an option of coordinating SSRA emissions data
collection with MACT performance testing. Facilities choosing to
perform coordinated testing would be expected to factor SSRA data
collection requirements into the MACT performance test plan. Commenters
support this approach, emphasizing that coordinated testing would
conserve the resources of both the regulatory authority and regulated
source. The Agency agrees with the commenters and continues to support
coordinated testing. There is no need, however, for today's final rule
to include regulatory language for coordinated testing since it is
simply matter of submitting and implementing a test plan which
accomplishes the objectives of both a risk burn and MACT performance
test.
Coordinated testing may not be possible for all hazardous waste
combustors subject to today's MACT standards. Some sources may not be
able to test under one set of conditions that addresses all data needs
for both MACT implementation and SSRAs. SSRA emissions testing
traditionally is performed under worst-case conditions, but may be
obtained under normal testing conditions when necessary.186
As noted in the April 1996 NPRM, as well as in this preamble, we
generally anticipate sources will conduct MACT performance testing
under conditions that are at the edge of the operating envelope or the
worst-case to ensure operating flexibility. Regardless of which test
conditions are used to collect SSRA emissions data, under the
coordinated testing scenario, those conditions should be consistent
with the MACT performance test to the extent possible.
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\186\ Criteria for determining the circumstances under which
SSRA emissions data should be collected using normal versus worst-
case testing conditions are provided in EPA's Guidance on Collection
of Emissions Data to Support Site-Specific Risk Assessments at
Hazardous Waste Combustion Facilities (EPA 530-D-98-002, August
1998).
---------------------------------------------------------------------------
Similarly, a source may experience difficulty integrating MACT
performance testing with SSRA emissions testing due to conflicting
goals in establishing enforceable operating parameters, i.e., a
parameter cannot be maximized for purposes of the SSRA data collection
while at the same time be properly maximized or minimized for purposes
of performance testing. It is additionally important to ensure that the
feed material used during the performance testing is appropriate for
SSRA emissions testing. When collecting emissions data for a SSRA,
testing with actual worst-case waste is preferred to ensure that the
testing material is representative of the toxic, persistence and
bioaccumulative characteristics of the waste that ultimately will be
burned. However, even if multiple tests need to be performed to
accomplish all of the objectives, it is still advantageous to conduct
these tests in the same general time frame to minimize mobilization and
sampling costs.
The timing of the required tests may cause difficulty for some
sources wishing to use coordinated testing. As we discussed in the May
1997 NODA, if the timing of the SSRA data collection does not coincide
with the MACT performance test requirement, the performance test should
not be unduly delayed. Commenters agree with this approach.
2. What Is Required for Risk Burn Testing?
We expect that sources for which coordinated testing is not
possible will need to obtain SSRA emissions data through a separate
risk burn. Similar to a traditional RCRA trial burn, risk burn testing
should be conducted pursuant to a test plan that is reviewed and
approved by the RCRA permitting authority. 40 CFR 270.10(k) provides
that the permitting authority may require the submittal of information
to establish permit conditions to ensure a facility's operations will
be protective of human health and the environment. This regulatory
requirement provides for the collection of emissions data, as
appropriate, for incorporation into a SSRA as well as for the
performance of the SSRA itself. We clarify in amendments to
Secs. 270.19, 270.22, 270.62 and 270.66 that the Director may apply
provisions from those sections, on a case-by-case basis, to establish a
regulatory framework for conducting the risk burn under Sec. 270.10(k)
and imposing risk-based conditions under Sec. 270.32(b)(2) (omnibus
provisions). This clarifying language is intended to prevent any
confusion from other language added to Secs. 270.19, 270.22, 270.62 and
270.66 today stating that
[[Page 52917]]
these provisions otherwise no longer apply once a source has
demonstrated compliance with the MACT standards and limitations of 40
CFR part 63, subpart EEE. (See Part Five, Section XI.B.3 for further
discussion.) Facilities and regulatory authorities may consult existing
EPA guidance documents for information regarding the elements of risk
burn testing.187
---------------------------------------------------------------------------
\187\ USEPA. ``Human Health Risk Assessment Protocol for
Hazardous Waste Combustion Facilities'' External Peer Review Draft.
EPA-530-D-98-001A,B&C. Date.; USEPA, ``Guidance on Collection of
Emissions Data to Support Site-Specific Risk Assessments at
Hazardous Waste Combustion Facilities'' EPA 530-D-98-002. August
1998.
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E. What Is a Change in Design, Operation, and Maintenance? (See
Sec. 63.1206(b)(6).)
The April 1996 NPRM noted that sources may change their design,
operation, or maintenance practices in a manner that may adversely
affect their ability to comply with the emission standards. These
sources would be required to conduct a new comprehensive performance
test to demonstrate compliance with the affected emission standards and
would be required to re-establish operating limits on the affected
parameters specified in Sec. 63.1209. (See 61 at FR 17518.) The
proposal stated that until a complete and accurate revised NOC is
submitted to the Administrator, sources would be permitted to burn
hazardous waste following such changes for time a period not to exceed
720 hours and only for the purposes of pretesting or comprehensive
performance testing. The approach in the April 1996 NPRM remains
appropriate, and we are adopting it in today's final rule with minor
modifications.
For changes made after submittal of your NOC that may adversely
affect compliance with any emission standard, as defined later in this
section, today's rule requires you to notify the Administrator at least
60 days prior to the change unless you document circumstances that
dictate that such prior notice is not reasonably feasible. The
notification must include a description of the changes and which
emission standards may be affected. The notification must also include
a comprehensive performance test schedule and test plan that will
document compliance with the affected emission standard(s). You must
conduct a comprehensive performance test to document compliance with
the affected emission standard(s) and establish operating parameter
limits as required and submit a revised NOC to the Administrator. You
also must not burn hazardous waste for more than a total of 720 hours
after the change and prior to submitting your NOC, and you must burn
hazardous waste during this time period only for the purposes of
pretesting or comprehensive performance testing.
Some commenters are uncomfortable with the proposed regulatory
language, stating that it was too generic and that the Agency could
require a comprehensive performance test even after minor changes in
maintenance practices. One commenter suggests that EPA incorporate a
list of changes significant enough to affect compliance, similar to
what is currently done in the RCRA permit modification classification
scheme in Appendix I of Sec. 270.42.
We intentionally proposed an approach that provides some degree of
flexibility to permit authorities. Individual facilities will need to
consult with these permit authorities who will make the decision on the
site-specific facts. We do not intend to require a comprehensive
performance test after minor modifications to system design, or after
implementing minor changes to operating or maintenance practices. We
considered incorporating sections of Appendix I of Sec. 270.42 to
further clarify when comprehensive performance tests would be
required.188 However, it is impossible to envision all
scenarios in which changes in design, operation, or maintenance
practices may or may not trigger the requirement of a complete, or even
partial, comprehensive performance test. Discussion of specific
scenarios is more suitable in an Agency guidance document as opposed to
regulatory provisions, and implemented on a site-specific basis. Thus,
the April 1996 NPRM set out the regulatory approach as well as can be
done, and we are adopting it today with minor modifications.
---------------------------------------------------------------------------
\188\ One approach would be to require performance tests for
modifications covered by the class 2 and class 3 permit
modifications associated with combustion source design and operating
parameter changes.
---------------------------------------------------------------------------
In the April 1996 NPRM, we did not address what must be done when
you change design, operation, or maintenance practices during the time
period between the compliance date and when you submit your NOC. If you
make a change during this time period, today's rule requires you to
revise your DOC, which is maintained on-site, to incorporate any
revised limits necessary to comply with the standards. For purposes of
this provision, today's rule defines ``change'' as any change in
reported design, operation, or maintenance practices you previously
documented to the Administrator in your comprehensive performance test
plan, NOC, DOC, or startup, shutdown, and malfunction plan.
Commenters point out that the proposal did not discuss
recordkeeping requirements necessary for the Administrator to determine
if you are adequately concluding that changes in design, operation, or
maintenance practices do not trigger a comprehensive performance test
requirement 189. As a result, today's rule requires you to
document in your operating record whenever you make a change (as
defined above) in design, operation, or maintenance practices,
regardless of whether the change may adversely affect your ability to
comply with the emission standards. See Sec. 63.1206(b)(6)(ii). You are
also required to maintain on site an updated comprehensive performance
test plan, NOC, and startup, shutdown, and malfunction plan that
reflect these changes. See Sec. 63.1211(c).
---------------------------------------------------------------------------
\189\ We cannot determine if a source has accurately concluded
that a change does not adversely affect its ability to comply with
the emission standards if we are never aware that changes were made
to the source.
---------------------------------------------------------------------------
F. What Are the Data In Lieu Allowances?
You are allowed to submit data from previous emissions tests in
lieu of performing a MACT performance test to set operating limits. See
Sec. 63.1207(c)(2). To use previous emissions test data, the data must
have been collected less than 5 years before the date you intend to
submit your notification of compliance. The data must also have been
collected as part of a test that was for the purpose of demonstrating
compliance with RCRA or CAA requirements. Additionally, you must submit
your request to use previous test data in your comprehensive
performance test plan which is submitted 1 year in advance of the MACT
performance test. Finally, you must schedule your subsequent MACT
performance test and MACT confirmatory test 5 years and 2.5 years
respectively following the date the emissions test data your submitting
was collected.
We developed this allowance in response to comments that suggested
we should allow previous RCRA testing to be used in lieu of performing
a new MACT performance test if the data could be used to demonstrate
compliance and establish operating limits to ensure compliance with the
MACT emissions standards. Commenters reasoned, and we agreed, that such
an allowance was reasonable and necessary for those sources that
[[Page 52918]]
must perform emissions tests to satisfy other state or federal
requirements. As we developed this allowance, we decided that it is
necessary to limit the age of the data and specify the date of the
following performance test because we need to be consistent with the
MACT performance test requirements with respect to testing frequency.
We can further justify the time and testing limitations of the data in
lieu of allowance by acknowledging that we don't want some sources
gaining an advantage over others by extending the date between
performance tests. However, we also weighed the fact that some sources
may be required to perform RCRA testing fairly close to the compliance
date or promulgation date of today's rule and we didn't want to
penalize them by forcing them to perform a new performance test before
five years had elapsed since their previous test. So we settled on an
approach that allows the use of previous emissions test data and
effectively sets the same testing frequency as is applied to test data
collected via a MACT performance test following the compliance date.
This approach doesn't penalize or favor any source over another and it
allows each source to take advantage of this provision when it makes
sense. For instance, a source may be granted approval to use data from
a RCRA trial burn performed 1 year before today's date, thus not
requiring the source to perform a comprehensive performance test 270
days following the compliance date. Instead, the source must schedule
its next MACT performance test five years after the date the test was
performed. However, the source must perform a confirmatory test 270
days following the compliance date because the test schedule for the
confirmatory test is also linked to the date of the performance test.
So in this situation the source must determine if its better to run the
comprehensive performance test on a normal schedule after the
compliance date or delay the comprehensive test and perform a
confirmatory test instead.
VI. What Is the Notification of Compliance?
A. What Are the Requirements for the Notification of Compliance?
You must submit to the Administrator the results of the
comprehensive performance test in a notification of compliance (NOC) no
later than three months after the conclusion of the performance test.
You must submit the initial NOC later than nine months following the
compliance date.
B. What Is Required in the NOC?
You must include the following information in the NOC:
--Results of the comprehensive performance test, continuous monitoring
system performance evaluation, and any other monitoring procedures or
methods that you conducted;
--Test methods used to determine the emission concentrations and
feedstream concentrations, as well as a description of any other
monitoring procedures or methods that you conducted;
--Limits for the operating parameters;
--Procedures used to identify the operating parameter limits specified
in Sec. 63.1209;
--Other information documenting compliance with the operating
requirements, including but not limited to automatic waste feed cutoff
system operability and operator training;
--A description of the air pollution control equipment and the
associated hazardous air pollutant that each device is designed to
control; and
--A statement from you or your company's responsible official that the
facility is in compliance with the standards and requirements of this
rule.
C. What Are the Consequences of Not Submitting a NOC?
The normal CAA enforcement procedures apply if you fail to submit a
timely notification of compliance. We do not adopt our proposed
approach that would have required you to immediately stop burning
hazardous waste if you failed to submit a timely NOC.
We proposed regulatory language stating that failure to submit a
notification of compliance by the required date would result in the
source being required to immediately stop burning hazardous waste. This
proposal was similar to requirements applied to BIFs certifying
compliance under RCRA. Under the proposal, if you wanted to burn
hazardous waste in the future, you would be required to comply with the
standards and permit requirements for new MACT and RCRA sources.
In the 1997 NODA, however, we proposed to rely on the regulating
agency's policy regarding enforcement response to govern the type of
enforcement response at a facility that fails to submit a notification
of compliance. Based on NODA comments and review of this enforcement
process, we are not including in the final rule regulatory language
addressing the consequences of failure to submit a timely or complete
NOC. Instead, we rely on the regulating agency's policy regarding
enforcement response to govern the type of enforcement response at a
facility that fails to meet a compliance deadline. This approach is
more practical to implementing today's MACT standards and is more
consistent with the way other MACT standards are implemented.
D. What Are the Consequences of an Incomplete Notification of
Compliance?
In response to our April 1996 NPRM, commenters state that we were
unclear as to the consequences of an incomplete NOC. Furthermore,
commenters state that it was important that we specify what is needed
and the consequences if an NOC is incomplete or more information is
needed. Additionally, commenters recommend that if the NOC contains
emission information, the certification statement, and a signature, we
should judge the NOC to be administratively complete and an acceptable
submission. In addition, commenters suggest that if the regulatory
official reviewing the NOC determines that additional information is
required, the source should be given ample time to submit that
information.
Our enforcement approach to incomplete submissions, under RCRA or
the CAA, is generally determined on a site-specific basis. We will not
attempt to foresee and develop enforcement responses to all the
possible levels of incompleteness for the NOC. This is beyond the scope
of our national rulemaking. Furthermore, defining what constitutes an
incomplete submission requires us to specifically prescribe a complete
submission, which is not possible for all situations or all source
designs. Some sources may require more detail than others in defining
the parameters necessary to determine compliance on a continuous basis.
Therefore, we instead define the minimum information necessary in the
submission and allow the implementing agency to determine if more
information is necessary in a facility's site-specific NOC.
In response to comments advocating that facilities be given ample
time to submit additional information required by the regulatory
official, we prefer to allow the implementing agency to determine the
time periods that will be granted to submit additional information
because some information requests may require widely varying degrees of
time and effort to develop. Many potential problems associated with
incomplete submissions can be prevented through interaction between
[[Page 52919]]
the source and the regulatory agency during the test plan review and
approval process. We do not want our rules to act as disincentive to
those discussions by providing a complete shield, regardless of the
severity of the omission.
E. Is There a Finding of Compliance?
We adopt the requirement we proposed for the regulatory agencies to
make a finding of compliance based on performance test results (see
Sec. 63.1206(b)(3)). This provision specifies that the regulatory
agency must determine whether an affected source is in compliance with
the emissions standards and other requirements of subpart EEE, as
provided by the general provisions governing findings of compliance in
Sec. 63.6(f)(3). Thus, the regulatory agency is obligated to make this
finding upon obtaining all the compliance information required by the
standards, including the written reports of performance test results,
monitoring results, and other applicable information. This includes,
but may not be limited to, the information submitted by the source in
its NOC.
VII. What Are the Monitoring Requirements?
In this section, we discuss the following topics: (1) The
compliance monitoring hierarchy that places a preference on compliance
with a CEMS; (2) how limits on operating parameters are established
from comprehensive performance test data; (3) status and use of CEMS
other than carbon monoxide, hydrocarbon, and oxygen CEMS; and (4) final
compliance monitoring requirements for each emission standard.
A. What Is the Compliance Monitoring Hierarchy?
We proposed the following three-tiered compliance monitoring
hierarchy in descending order of preference to ensure compliance with
the emission standards: (1) Use of a continuous emission monitoring
system (CEMS) for a hazardous air pollutant; (2) absent a CEMS for that
hazardous air pollutant, use of a CEMS for a surrogate of that
hazardous air pollutant and, when necessary, setting limits on
operating parameters to account for the limitations of using
surrogates; and (3) lacking a CEMS for either, requiring periodic
emissions testing and site-specific limits on operating parameters.
Accordingly, we proposed to require the use of carbon monoxide,
hydrocarbon, oxygen, particulate matter, and total mercury CEMS. We
also proposed performance specifications for multimetal, hydrochloric
acid, and chlorine gas CEMS to give sources the option of using a CEMS
for compliance with the semivolatile and low volatile metal emissions
standards, and the hydrochloric acid/chlorine gas emission standard.
Commenters question the availability and reliability of CEMS other
than those for carbon monoxide, hydrocarbon, and oxygen. We concur with
some of the commenters' concerns and are not requiring use of a total
mercury CEMS in the final rule or specifying the installation deadline
and performance specifications for particulate matter CEMS. In
addition, we have not promulgated performance specifications for these
CEMS or multimetal, hydrochloric acid, and chlorine gas CEMS. We
nonetheless continue to encourage sources to evaluate the feasibility
of using these CEMS to determine the performance specifications,
correlation acceptance criteria, and detector availability that can be
achieved. Sources may request approval from permitting officials under
Sec. 63.8(f) to use CEMS to document compliance with the emission
standards in lieu of periodic performance testing and compliance with
limits on operating parameters. See discussion in Section VII.C below
on these issues.
B. How Are Comprehensive Performance Test Data Used To Establish
Operating Limits?
In this section, we discuss: (1) The definitions of terms related
to monitoring and averaging periods; (2) the rationale for the
averaging periods for operating parameter limits, (3) how comprehensive
performance test data are averaged to calculate operating parameter
limits; (4) how the various types of operating parameters are
monitored/established; (5) how nondetect performance test feedstream
data are handled; and (6) how rolling averages are calculated
initially, upon intermittent operations, and when the hazardous waste
feed is cut off.
1. What Are the Definitions of Terms Related to Monitoring and
Averaging Periods?
In the April 1996 NPRM, we proposed definitions for several terms
that relate to monitoring and averaging periods. For the reasons
discussed below, we conclude that the proposed definitions are
appropriate and are adopting them in today's rule. We also finalize
definitions for ``average run average'' and ``average highest or lowest
rolling average'' which were not proposed. We conclude these new
definitions are necessary to clarify the meaning and intent of
regulatory provisions associated with the monitoring requirements that
are discussed in Part 5, Section VII.D. of this preamble.
We promulgate the following definitions in today's rule (see
Sec. 63.1201).
``Average highest or lowest rolling average'' means the average of
each run's highest or lowest rolling average run within the test
condition for the applicable averaging period.
``Average run average'' means the average of each run's average of
all associated one minute values.
``Continuous monitor'' means a device that: (1) Continuously
samples a regulated parameter without interruption; (2) evaluates the
detector response at least once every 15 seconds; and (3) computes and
records the average value at least every 60 seconds, except during
allowable periods of calibration and as defined otherwise by the CEMS
Performance Specifications in appendix B of part 60.
``Feedrate operating limits'' means limits on the feedrate of
materials (e.g., metals, chlorine) to the combustor that are
established based on comprehensive performance testing. The limits are
established and monitored by knowing the concentration of the limited
material (e.g., chlorine) in each feedstream and the flow rate of each
feedstream.
``Feedstream'' means any material fed into a hazardous waste
combustor, including, but not limited to, any pumpable or nonpumpable
solid, liquid, or gas.
``Flowrate'' means the rate at which a feedstream is fed into a
hazardous waste combustor.
``Instantaneous monitoring'' means continuously sampling,
detecting, and recording the regulated parameter without use of an
averaging period.
``One-minute average'' means the average of detector responses
calculated at least every 60 seconds from responses obtained at least
each 15 seconds.
``Rolling average'' means the average of all one-minute averages
over the averaging period.
One commenter opposes the requirement to take instrument readings
every 15 seconds. This commenter contends that such an approach is
simply impractical, unnecessary, and imposes a harsh burden upon
members of the regulated community. Another commenter maintains that
the CEMS Data Acquisition System should be capable of sampling the
analyzer outputs at least every 15 seconds. With today's processing
power and speed, the commenter states that this can easily be achieved.
We agree with the second commenter and are requiring instrument
[[Page 52920]]
readings at least every 15 seconds because this is currently required
in the Boilers and Industrial Furnace rulemaking. (See
Sec. 266.102(e)(6))
Another commenter states that the Agency's definition of
``instantaneous monitoring'' of combustion chamber pressure to control
combustion system leaks is not clear.190 The commenter
states that, although an instantaneous limit cannot be exceeded at any
time, continuous monitoring systems are required to detect parameter
values only once every 15 seconds. We note that the final rule requires
instantaneous monitoring only for the combustion chamber pressure limit
to control combustion system leaks. The rule requires an automatic
waste feed cutoff if the combustion chamber pressure at any time (i.e.,
instantaneously) exceeds ambient pressure (see Sec. 63.1209(p)). The
definition of a continuous monitoring system is that it must record
instrument readings at least every 15 seconds. For instantaneous
monitoring of pressure, the detector must clearly record a response
more frequently than every 15 seconds.191 It must detect and
record pressure constantly without interruption and without any
averaging period.
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\190\ ``Combustion system leaks'' is the term used in today's
rule to refer to leaks that are called fugitive emissions under
current RCRA regulations. We use the term combustion system leaks to
refer to those emissions because the term fugitive emissions has
other meanings under part 63.
\191\ Typical pressure transducers in use today are capable of
responding to pressure changes once every fifty milliseconds. See
USEPA, ``Final Technical Support Document for Hazardous Waste
Combustor MACT Standards, Volume IV: Compliance with the Hazardous
Waste Combustor Standard,'' July 1999.
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2. What Is the Rationale for the Averaging Periods for the Operating
Parameter Limits?
The final rule establishes the following averaging periods: (1) No
averaging period (i.e., instantaneous monitoring) for maximum
combustion chamber pressure to control combustion system leaks; (2) 12-
hour rolling averages for maximum feedrate of mercury, semivolatile
metals, low volatile metals, chlorine, and ash (for incinerators); and,
(3) one-hour averaging periods for all other operating parameters. As
discussed later in this section, we conclude that the proposed ten-
minute averaging periods are not necessary, on a national basis, to
better ensure compliance with the emission standards at hazardous waste
combustors, and have not adopted these averaging periods in this
rulemaking.
a. When Is an Instantaneous Limit Used? An instantaneous limit is
required only for maximum combustion chamber pressure to control
combustion system leaks. This is because any perturbation above the
limit may result in uncontrolled emissions exceeding the standards.
b. When Is an Hourly Rolling Average Limit Used? An hourly rolling
average limit is required for all parameters that are based on
operating data from the comprehensive performance test, except
combustion chamber pressure and feedrate limits. Hourly rolling
averages are required for these parameters rather than averaging
periods based on the duration of the performance test because we are
concerned that there may be a nonlinear relationship between operating
parameter levels and emission levels of hazardous air pollutants.
c. Why Has the Agency Decided Not to Adopt Ten-Minute Averaging
Periods? Dual ten-minute and hourly rolling averages were proposed for
most parameters for which limits are based on the comprehensive
performance test. See 61 FR at 17417. We proposed ten-minute rolling
averages in addition to hourly rolling averages for these parameters
because short term excursions of the parameter can result in a
disproportionately large excursion of the hazardous air pollutant being
controlled.
Commenters claim that the Agency's concerns with emission
excursions due to short term perturbations of these operating
parameters were not supported with data and are therefore unjustified,
and claim that averaging periods shorter than those required in the
existing BIF regulations would provide no environmental benefit.
We acknowledge that the Agency does not have extensive short-term
emission data that show operating parameter excursions can result in
disproportionately large excursions of hazardous air pollutants being
emitted. These short-term data cannot be obtained without the use of
continuous emission monitors that measure dioxin/furans, metals, and
chlorine on a real-time basis. Such monitors, for the most part, are
not currently used for compliance purposes at hazardous waste
combustors. However, known relationships between operating parameters
and hazardous air pollutant emissions indicate that a nonlinear
relationship exists between operating parameter levels and emissions.
This nonlinear relationship can result in source emissions that exceed
levels demonstrated in the performance test if the operating parameters
are not properly controlled. An explanation of these nonlinear
relationships, including examples that explain why this relationship
can result in daily emissions that exceed levels demonstrated in the
performance test, are included in the Final Technical Support
Document.192 Thus, at least in theory, an environmental
benefit can result from shorter averaging periods, including ten-minute
rolling averages and perhaps instantaneous readings in certain
situations.
---------------------------------------------------------------------------
\192\ See USEPA, ``Final Technical Support Document for
Hazardous Waste Combustor MACT Standards, Volume IV: Compliance With
the Hazardous Waste Combustor Standards, July 1999, Chapters 2 and
3.
---------------------------------------------------------------------------
We also acknowledge, however, that the Agency's ability to assess
this potential benefit in practice for all hazardous waste combustors
affected by this final rule is limited significantly by the paucity of
short-term, minute-by-minute, operating parameter data. Without this
data we cannot effectively evaluate whether operating parameter
excursions occur to an extent that warrant national ten-minute
averaging period requirements for all hazardous waste combustors. We
therefore conclude that averaging period requirements shorter than
those required by existing BIF regulations are not now appropriate for
adoption on a national level, and do not adopt ten-minute averaging
period requirements in this rulemaking.
We maintain, however, that there may be site-specific circumstances
that warrant averaging periods shorter than one hour in duration,
including possibly instantaneous measurements. Regulatory officials may
determine, on a site-specific basis, that shorter averaging periods are
necessary to better assure compliance with the emission standards. The
provisions in Sec. 63.1209(g)(2) authorize the regulatory official to
make such a determination. Factors that may be considered when
determining whether shorter averaging periods are appropriate include
(1) the ability of a source to effectively control operating parameter
excursions to levels achieved during the performance test; (2) the
source's previous compliance history regarding operating parameter
limit exceedances; and (3) the difference between the source's
performance test emission levels and the relevant emission standard.
For additional information, see the Final Technical Support Document,
Volume 4, Chapter 2.
d. What Is the Basis for 12-Hour Rolling Averages for Feedrates?
The rule requires 12-hour averages for the feedrate of mercury,
semivolatile metals, low volatile metals, chlorine, and ash (for
incinerators) because feedrate and emissions are, for the most part,
linearly
[[Page 52921]]
related. A 12-hour averaging period for feedrates is appropriate
because it is the upper end of the range of time required to perform
three runs of a comprehensive performance test. Thus, a 12-hour
averaging period will ensure (if all other factors affecting emissions
are constant) that emissions will not exceed performance test levels
during any interval of time equivalent to the time required to conduct
a performance test. A 12-hour averaging period is also achievable and
appropriate from a compliance perspective because the emission
standards are based on emissions data obtained over (roughly) these
sampling periods.193
---------------------------------------------------------------------------
\193\ See Chemical Waste Management v. EPA, 976 F.2d, 2, 34
(D.C. Cir. 1992) (It is inherently reasonable to base compliance on
the same type of data used to establish the requirement).
---------------------------------------------------------------------------
e. Has the Agency Over-Specified Compliance Requirements? Some
commenters state that the Agency is over-specifying compliance
requirements by requiring limits on many operating parameters,
requiring dual ten-minute and hourly rolling average limits on many
parameters, and requiring that sources interlock the operating
parameter limits with the automatic waste feed cutoff system. These
commenters wrote that this compliance regime may lead to system over-
control and instability, and an unreasonable and unnecessary increase
in automatic waste feed cutoffs, a result that is contrary to good
process control principles. They propose that we work with industry to
develop a process control system and performance specification
regulatory approach to establish minimum system standards. These would
include: (1) Minimum process instrument sampling time; (2) maximum
calculation capability for output signals; (3) minimum standard for
process control sequences; and (4) minimum requirements for
incorporating automatic waste feed cutoffs into the control scheme. The
specifications would be incorporated into guidance, rather than
regulation. Commenters suggest that the rule should only specify
general goals, similar to the guidance approach we took for hazardous
waste incinerators in the 1981 RCRA regulations.194
---------------------------------------------------------------------------
\194\ The incinerator regulations promulgated in 1981, at the
outset of the RCRA regulatory program, used such a general guidance
approach. However, sources have had over 15 years since then to gain
experience with process control techniques associated with the
combustion of hazardous waste.
---------------------------------------------------------------------------
We evaluated these comments carefully, balancing the need to
provide industry with operational flexibility with the need for
compliance assurance. As previously discussed, we are not adopting ten-
minute averaging period requirements in this rulemaking, although it
can be imposed on a site-specific basis under appropriate
circumstances. This addresses commenter's concerns that relate to the
complexity of the proposed dual averaging period requirements. We
acknowledge, however, that today's rule requires that more operating
parameter limits be interlocked to the automatic waste feed cutoff
system than is currently required by RCRA regulations. Nonetheless, we
conclude that the compliance regime of today's final rule is necessary
to ensure compliance with the emission standards and will not overly
constrain process control systems for the following reasons.
Automatic waste feed cutoffs are (by definition) automatic, and the
control systems used to avoid automatic waste feed cutoffs require
adequate response time and are primarily site-specific in design. The
closer a source pushes the edge of the operating envelope, the better
that control system must perform to ensure that an operating parameter
limit (and emission standard) is not exceeded. Therefore, a source has
extensive control over the impact of these requirements.
Under the compliance regime of today's rule, sources will continue
to perform comprehensive performance testing under ``worst case''
conditions as they currently do under RCRA requirements to establish
limits on operating parameters that are well beyond normal levels. This
cushion between normal operating levels and operating parameter limits
enables the source to take corrective measures well before a limit is
about to be exceeded, thus avoiding an automatic waste feed cutoff.
Regulatory officials do not have the extensive resources that would
be required to develop and implement industry-specific control
guidelines and we are not confident that this approach would provide
adequate compliance assurance. Although specifying only emissions
standards and leaving the compliance method primarily up to the source
and the permit writer (aided by guidance) would provide flexibility, it
would place a burden on the permit writers and the source during the
development and approval of the performance test plan and the finding
of compliance subsequent to Notification of Compliance. In addition,
this level of interaction between permitting officials and the source
is contrary to our policy of structuring the MACT standards to be as
self-implementing as possible.195 The Agency therefore
maintains its position that the compliance scheme adopted in today's
rule, is appropriate.
---------------------------------------------------------------------------
\195\ The time that would be associated with this type of review
and negotiation between permit writer and source would be better
spent on developing, reviewing, and approving the comprehensive
performance test plan under today's compliance regime.
---------------------------------------------------------------------------
f. Why Isn't Risk Considered in Determining Averaging Periods?
Several commenters state that long averaging periods (e.g., monthly
metal feedrate rolling averages) for the operating parameter limits and
CEMS-monitored emission standards would be appropriate. These
commenters believe that long averaging periods would be appropriate
given that the Agency has performed a risk assessment and concluded
that the emission standards would be protective over long periods of
exposure. They state that long averaging periods would ensure that
emissions are safe and reduce compliance costs.
Consideration of risk is not an appropriate basis for determining
averaging periods to ensure compliance with the technology-based MACT
emission standards.196 As previously stated, we must
establish averaging periods that ensure compliance with the emission
standard for time durations equivalent to the emission sampling periods
used to demonstrate compliance. Longer averaging periods would not
ensure compliance with the emission standard because many of the
operating parameters do not relate to emissions linearly.
---------------------------------------------------------------------------
\196\ We note, however, that within eight years of promulgating
MACT standards for a source category, we must consider risk in
determining under section 112(f) whether standards more stringent
than MACT are necessary to provide an ample margin of safety to
protect public health and the environment.
---------------------------------------------------------------------------
In addition, a longer averaging period is not warranted even for
those operating parameters than may relate linearly to emissions
because this would allow a source to emit hazardous air pollutants in
excess of the emission standard for times periods equivalent to the
stack emission sampling periods used to demonstrate compliance. For
example, a monthly averaging period for metal feedrates could result in
a source emitting metals at a level three times the regulatory standard
continuously for a one week period.197 This would not be
consistent with the level of control that was achieved by the best
performing sources in our data base. Modifying the results of the MACT
process based on risk considerations is thus contrary to Congressional
intent that MACT
[[Page 52922]]
standards, at a minimum, must represent the level of control being
achieved by the average of the best performing 12 percent of the
sources. We therefore conclude that we must limit averaging times at
least to time durations equivalent to the emission sampling periods
used to demonstrate compliance.
---------------------------------------------------------------------------
\197\ For this to occur, the source would have to emit metals
far below the standard for time periods before and after this one-
week period.
---------------------------------------------------------------------------
g. Will Relaxing Feedrate Averaging Times Increase Environmental
Loading? One commenter questions whether relaxing the averaging time
for the feedrate of metals and chlorine from an hourly rolling average
under current RCRA regulations to the 12-hour rolling average of
today's rule would increase total environmental loading of pollutants
and be counter to the Agency's pollution prevention objectives.
Contrary to the commenter's concern, we conclude that today's rule will
decrease environmental loading of hazardous air pollutants because the
emission standards are generally more stringent than current RCRA
standards. Today's standards more than offset any difference in
environmental loading associated with longer averaging times. As
previously discussed, the averaging periods in today's rule were chosen
to ensure compliance with the emission standard for intervals of time
equivalent to the time required to conduct a performance test.
Although current RCRA standards generally establish hourly rolling
averages for the feedrate of metals, sources are actually allowed to
establish up to 24-hour rolling averages for arsenic, beryllium,
chromium, cadmium, and lead, provided they restrict the feedrate of
these metals at any time to ten times what would be normally allowed
under an hourly rolling average basis. For these reasons, the
commenter's concern is not persuasive.
3. How Are Performance Test Data Averaged To Calculate Operating
Parameter Limits?
The rule specifies which of two techniques you must use to average
data from the comprehensive performance test to calculate limits on
operating parameters: (1) Calculate the limit as the average of the
maximum (or minimum, as specified) rolling averages for each run of the
test; or (2) calculate the limit as the average of the test run
averages for each run of the test.
Hourly rolling averages for two parameters--combustion gas flowrate
(or kiln production rate as a surrogate) and hazardous waste feedrate--
are based on the average of the maximum hourly rolling averages for
each run. Hourly rolling average and 12-hour rolling average limits for
all other parameters, however, are based on the average level occurring
during the comprehensive performance test. We determined that this more
conservative approach is appropriate for these parameters because they
can have a greater effect on emissions, and because it is consistent
with how manual method emissions results are determined.198
---------------------------------------------------------------------------
\198\ Manual method emission test results for each run
represents average emissions over the entire run.
---------------------------------------------------------------------------
These are examples of how the averages work. The hourly rolling
average hazardous waste feedrate limit for a source is calculated using
the first technique. If the highest hourly rolling averages for each
run of the comprehensive performance test were 200 lbs/hour, 210 lbs/
hr, 220 lbs/hr, the hourly rolling average feedrate limit would be 210
lbs/hr.
The second approach uses the average of the test run averages for a
given test condition to calculate the limit. Each test run average is
calculated by summing all the one-minute readings within the test run
and dividing that sum by the number of one-minute readings. For
example, if: (1) The sum of all the one-minute semivolatile metal
feedrate readings for each run within a test condition is 2,400 lbs/
hour, 2,500 lbs/hour, and 2,600 lbs/hour; and (2) there are 240, 250,
and 200 one-minute readings in each run, respectively; then (3) the
average feedrate for each of these three runs is 10 lbs/hour, 10 lbs/
hour, and 13 lbs/hour, respectively. The 12-hour rolling average
semivolatile metal feed rate limit for this example is the average of
these three values: 11 lbs/hour. This averaging methodology is not
equivalent to an approach where the limit is calculated by taking the
time-weighted average over all three runs within the test condition,
because, as noted by the example, sampling times may be different for
each run. The time-weighted average feedrate over all three test runs
for the previous example is equivalent to 10.9 lbs/hr.199
Although the two averaging techniques may not result in averages that
are significantly different, we conclude that basing the limits on the
average of the test run averages is more appropriate, because this
approach is identical to how we determine compliance with the emission
standards.
---------------------------------------------------------------------------
\199\ This time weighted average is calculated by summing all
the one-minute feedrate values in the test condition and dividing
that sum by the number of one minute readings in the test condition.
---------------------------------------------------------------------------
These averaging techniques are the same as we proposed (see 61 FR
at 17418).200 A number of commenters object to the more
conservative second technique of basing the limits on the average
levels that occur during the test. The commenters claim that this
approach ensures a source would not comply with the limits 50% of the
time when operating under the same conditions as the performance test.
Further, they are concerned that this approach would establish
operating parameter limits that would ``ratchet'' emissions to levels
well below the standards, and further ratcheting would occur with each
subsequent performance test (i.e., because the current operating limits
could not be exceeded during subsequent performance testing). Some
commenters prefer the approach of setting the limit as the average of
the highest (or lowest) rolling average from each run, technique one
above, which is the same approach used in the BIF rule.
---------------------------------------------------------------------------
\200\ Except that average hourly rolling average limits are
calculated as the average of the test run averages rather than
simply the average over all runs as proposed.
---------------------------------------------------------------------------
Notwithstanding the conservatism of the promulgated approach
(technique two above) for many operating parameter limits, we maintain
that the approach results in achievable limits and is necessary to
ensure compliance with the emission standards. Comprehensive
performance tests are designed to demonstrate compliance with the
emission standards and establish corresponding operating parameter
limits. Thus, sources will operate under ``worst-case'' conditions
during the comprehensive performance tests, just as they do currently
for RCRA trial burns. Given that the source can readily control (during
the performance test and thereafter) the parameters for which limits
are established based on the average of the test run averages during
performance testing (i.e., rather than on the average of the highest
(or lowest) hourly rolling averages), and that these parameters will be
at their extreme levels during the performance test, the limits are
readily achievable.
There may be situations, however, where a source cannot
simultaneously demonstrate worst-case operating conditions for all the
regulated operating parameters. An example of this may be minimum
combustion chamber temperature and maximum temperature at the inlet to
the dry particulate matter control device because when the combustion
chamber temperature is minimized, the inlet temperature to the control
device may also be minimized. Sources should consult permitting
officials to resolve
[[Page 52923]]
compliance difficulties associated with conflicting operating
parameters. Potential solutions to conflicting parameters could be to
conduct the performance test under two different modes of operation to
set these conflicting operating parameter limits, or for the
Administrator to use the discretionary authority provided by
Sec. 63.1209(g)(2) to set alternative operating parameter limits.
We address commenters' concern that subsequent performance tests
would result in a further ratcheting down of operating parameter limits
by waiving the operating limits during subsequent comprehensive
performance tests (see Sec. 63.1207(h)). The final rule also waives
operating limits for pretesting prior to comprehensive performance
testing for a total operating time not to exceed 720 hours. See
discussion in Part Five, Section VI for more information on this
provision.
Some commenters suggest that we use a statistical analysis to
determine rolling average limits, such that the limits are calculated
as the mean plus or minus three standard deviations of all rolling
averages for all runs. Commenters state that this would ensure that the
operating parameter limits are achievable. If such an approach were
adopted, there would be no guarantee that a source is maintaining
compliance with the emission standards for the time durations of the
manual stack sampling method used to demonstrate compliance during the
comprehensive performance test. Such an approach could conceivably
encourage a source to intentionally vary operating parameter levels
during the comprehensive performance test to such an extent that the
statistically-derived rolling average limits would be significantly
higher than the true average of the test condition. This could also
result in widely varying statistical correction factors from one source
to another, which is undesirable for reasons of consistency and
fairness.
Such a statistical approach prevents us from establishing the
minimum emission standards that Congress generally envisioned under
MACT because we would not be assured that the sources are achieving the
emission standard. We would also have difficulty estimating
environmental benefits if this statistical approach were used because
we would not know what level of emission control each source achieves.
Again, the methodology promulgated for averaging performance test data
to calculate operating parameter limits results in limits that are
achievable and necessary to ensure compliance with the emission
standards for time durations equivalent to emission sampling periods.
Several commenters oppose the compliance regime whereby limits on
operating parameters are established during performance testing. They
are concerned that this approach encourages sources to operate under
worst-case conditions during testing. One commenter states that this
approach effectively punishes sources for demonstrating emissions
during their performance test that are lower than the standards (i.e.,
by establishing limits on operating parameters that would be well below
those needed to comply with the standards).
We understand these concerns, but absent the availability of
continuous emissions monitoring systems, we are unaware of another
compliance assurance approach that effectively addresses the (perhaps
unique) problem posed by hazardous waste combustors. The Agency is
using this same approach to implement the RCRA regulations for these
sources. Compliance assurance for hazardous waste combustors cannot be
maintained using the general provisions of Subpart A in Part 63--
procedures that apply to all MACT sources unless we promulgate
superseding provisions for a particular source category. Those
procedures require performance testing under normal operating
conditions, but operating limits are not established based on
performance test operations. This approach is appropriate for most
industrial processes because process constraints and product quality
typically limit ``normal'' operations to a fairly narrow range that is
easily defined.
Hazardous waste combustors may be somewhat unique MACT sources,
however, in that the characteristics of the hazardous waste feed (e.g.,
metals concentration, heating value) can vary over a wide range and
have a substantial effect on emissions of hazardous air pollutants. In
addition, system design, operating, and maintenance features can
substantially affect pollutant emissions. This is not the same
situation for many other MACT source categories where feedstream
characteristics and system design, operation, and maintenance features
must be confined to a finite range so that the source can continue to
produce a product. Hazardous waste incinerators do not have such
inherent controls (i.e., because they provide a waste treatment service
rather than produce a product), and cement and lightweight aggregate
kilns can vary substantially hazardous waste characteristics in the
fuel, as well as system design, operation, and maintenance features and
still produce marketable product.
To address commenters' concerns at least in part, however, we have
included a metals feedrate extrapolation provision in the final rule.
This will reduce the incentive to spike metals in feedstreams during
performance testing (and thus reduce the cost of testing, the hazard to
test crews, and the environmental loading) by explicitly allowing
sources to request approval to establish metal feedrate limits based on
extrapolating upward from levels fed during performance testing. See
discussion in Section VII.D.4 below, and Secs. 63.1209(l)(1) and
63.1209(n)(2)(ii).
4. How Are the Various Types of Operating Parameters Monitored or
Established?
The operating parameters for which you must establish limits can be
categorized according to how they are monitored or established as
follows: (1) Operating parameters monitored directly with a continuous
monitoring system; (2) feedrate limits; and (3) miscellaneous operating
parameters. (Each of these parameters is discussed in Section VII.D
below.)
a. What Operating Parameters Are Monitored Directly with a
Continuous Monitoring System? Operating parameters that are monitored
directly with a continuous monitoring system include: Combustion gas
temperature in the combustion chamber and at the inlet to a dry
particulate matter control device; baghouse pressure drop; for wet
scrubbers, pressure drop across a high energy wet scrubber (e.g.,
venturi, calvert), liquid feed pressure, pH, liquid-to-gas ratio,
blowdown rate (coupled with either a minimum recharge rate or a minimum
scrubber water tank volume or level), and scrubber water solids
content; minimum power input to each field of an electrostatic
precipitator; flue gas flowrate or kiln production rate; hazardous
waste flowrate; and adsorber carrier stream flowrate. These operating
parameters are monitored and recorded on a continuous basis during the
comprehensive performance test and during normal operations. The
continuous monitoring system also transforms and equates the data to
its associated averaging period during the performance test so that
operating parameter limits can be established. The continuous
monitoring system must operate in conformance with Sec. 63.1209(b).
b. How Are Feedrate Limits Monitored? Feedrate limits are monitored
by knowing the concentration of the regulated parameter
[[Page 52924]]
in each feedstream and continuously monitoring the flowrate of each
feedstream. See Sec. 63.1209(c)(4). You must establish limits on the
feedrate parameters specified in Sec. 63.1209, including: semivolatile
metals, low volatile metals, mercury; chlorine, ash (for incinerators),
activated carbon, dioxin inhibitor, and dry scrubber sorbent. The
flowrate continuous monitoring system must operate in conformance with
Sec. 63.1209(b).
c. How Are the Miscellaneous Operating Parameters Monitored/
Established? Other operating parameters specified in Sec. 63.1209
include: Specifications for activated carbon, acid gas sorbent,
catalyst for catalytic oxidizers, and dioxin inhibitor; and maximum age
of carbon in a carbon bed. Because each of these operating parameters
may be unique to your source, you are expected to characterize the
parameter (e.g., using manufacturer specifications) and determine how
it will be monitored and recorded. This information must be included in
the comprehensive performance test plan that will be reviewed and
approved by permitting officials.
5. How Are Rolling Averages Calculated Initially, Upon Intermittent
Operations, and When the Hazardous Waste Feed Is Cut Off?
a. How Are Rolling Averages Calculated Initially? You must begin
complying with the limits on operating parameters specified in the
Documentation of Compliance on the compliance date.201 See
Sec. 63.1209(b)(5)(i). Given that the one-hour, and 12-hour rolling
averages for limits on various parameters must be updated each minute,
this raises the question of how rolling averages are to be calculated
upon initial startup of the rolling average requirements. We have
determined that an operating parameter limit will not become effective
on the compliance date until you have recorded enough monitoring data
to calculate the rolling average for the limit. For example, the hourly
rolling average limit on the temperature at the inlet to an
electrostatic precipitator does not become effective until you have
recorded 60 one-minute average temperature values on the compliance
date. Given that compliance with the standards begins nominally at
12:01 am on the compliance date, the hourly rolling average temperature
limit does not become effective as a practical matter until 1:01 am on
the compliance date. Similarly, the 12-hour rolling average limit on
the feedrate of mercury does not become effective until you have
recorded 12 hours of one-minute average feedrate values after the
compliance date. Thus, the 12-hour rolling average feedrate limits
become effective as a practical matter at 12:01 pm on the compliance
date.
---------------------------------------------------------------------------
\201\ The operating parameters for which you must specify limits
are provided in Sec. 63.1209. You must include these limits in the
Documentation of Compliance, and you must record the Documentation
of Compliance in the operating record.
---------------------------------------------------------------------------
Although we did not specifically address this issue at proposal,
commenters raised the question in the context of CEMS. Given that the
same issue applies to all continuous monitoring systems, we adopt the
same approach for all continuous monitoring systems, including CEMS.
See discussion below in Section VII.C.5.b. We adopt the approach
discussed here because a rolling average limit on an operating
parameter does not exist until enough one-minute average values have
been obtained to calculate the rolling average.
b. How Are Rolling Averages Calculated upon Intermittent
Operations? We have determined that you are to ignore periods of time
when one-minute average values for a parameter are not recorded for any
reason (e.g., source shutdown) when calculating rolling averages. See
Sec. 63.1209(b)(5)(ii). For example, consider how the hourly rolling
average for a parameter would be calculated if a source shuts down for
yearly maintenance for a three week period. The first one-minute
average value recorded for the parameter for the first minute of
renewed operations is added to the last 59 one-minute averages before
the source shutdown for maintenance to calculate the hourly rolling
average.
We adopt this approach for all continuous monitoring systems,
including CEMS (see discussion below in Section VII.C.5.b) because it
is simple and reasonable. If, alternatively, we were to allow the
``clock to be restarted'' after an interruption in recording parameter
values, a source may be tempted to ``clean the slate'' of high values
by interrupting the recording of the parameter values (e.g., by taking
the monitor off-line for a span or drift check). Not only would this
mean that operating limits would not be effective again until an
averaging period's worth of values were recorded, but it would be
contrary to our policy of penalizing a source for operating parameter
limit exceedances by not allowing hazardous waste burning to resume
until the parameter is within the limit. Not being able to burn
hazardous waste during the time that the parameter exceeds its limit is
intended to be an immediate economic incentive to minimize the
frequency, duration, and intensity of exceedances.
c. How Are Rolling Averages Calculated when the Hazardous Waste
Feed Is Cut Off? Even though the hazardous waste feed is cut off, you
must continue to monitor operating parameters and calculate rolling
averages for operating limits. See Sec. 63.1209(b)(5)(iii). This is
because the emission standards and operating parameter limits continue
to apply even though hazardous waste is not being burned. See, however,
the discussion in Part Five, Sections I.C and I.D above for exceptions
(i.e., when a hazardous waste combustor is not burning hazardous waste,
the emission standards and operating requirements do not apply: (1)
During startup, shutdown, and malfunctions; or (2) if you document
compliance with other applicable CAA section 112 or 129 standards).
6. How Are Nondetect Performance Test Feedstream Data Handled?
You must establish separate feedrate limits for semivolatile metal,
low volatile metal, mercury, total chlorine, and/or ash for each
feedstream for which the comprehensive performance test feedstream
analysis determines that these parameters are not present at detectable
levels. The feedrate limit must be defined as nondetect at the full
detection limit achieved during the performance test. See
Sec. 63.1207(n).
You will not be deemed to be exceeding this feedrate limit when
detectable levels of the constituent are measured, provided that: (1)
Your total system constituent feedrate, considering the detectable
levels in the feedstream (whether above or below the detection limit
achieved during the performance test) that is limited to nondetect
levels, is below your total system constituent feedrate limit; or (2)
except for ash, your uncontrolled constituent emission rate for all
feedstreams, calculated in accordance with the procedures outlined in
the performance test waiver provisions (see Sec. 63.1207(m)) are below
the applicable emission standards.
We did not address in the April 1996 NPRM how you must handle
nondetect compliance test feedstream results when determining feedrate
limits, nor did commenters suggest an approach. After careful
consideration, we conclude that the approach presented above is
reasonable and appropriate.
The LWAK industry has expressed concern about excessive costs with
compliance activities that would be needed for the mercury standard.
They
[[Page 52925]]
claim that the increased costs associated with achieving lower mercury
detection limits are large, and does not result in significant
environmental benefits.
The final rule includes four different methods an LWAK can use to
comply with the mercury emission standard in order to provide maximum
flexibility. The basic compliance approach (described below) does not
require an LWAK to achieve specified minimum mercury detection limits
for mercury standard compliance purposes.202 Under this
approach, analytical procedures that achieve given detection limits are
evaluated on a site-specific basis as part of the waste analysis plan
review and approval process, which is submitted as part of the
performance test plan. An LWAK can make the case to the regulatory
official that the increased costs associated with achieving a very low
mercury detection limit is not warranted. We therefore do not believe
that the LWAK industry will incur significant additional analytical
costs over current practices for daily mercury compliance activities.
We acknowledge, however, that site-specific circumstances may lead a
regulatory official to conclude that lower detection limits are
warranted. To better understand this concept, the following paragraphs
summarize this basic mercury emission standard compliance scheme and
discusses why a regulatory official may determine, on a site-specific
basis, that lower detection limits are needed to better assure
compliance with the emission standard.
---------------------------------------------------------------------------
\202\ The other three approaches are (1) performance test waiver
provisions (see preamble, part 5, section X.B); (2) alternative
standards when raw materials cause an exceedance of the emission
standard (see preamble, part 5, section X.A); and, (3) alternative
mercury standards for kilns that have non-detect levels of mercury
in the raw material (see preamble, part 5, section X.A). These
mercury standard compliance alternatives require a source to achieve
feedstream detection limits that either ensure compliance with an
emission standard or ensure compliance with a hazardous waste
feedrate limit that is used in lieu of a numerical emission
standard. See previous referenced preamble for further discussion.
---------------------------------------------------------------------------
Under this basic approach, the source conducts a performance test
and samples the emissions for mercury to demonstrate compliance with
the emission standard. To ensure compliance with the emission standard
during day-to-day operations, the source must comply with mercury
feedrate limits that are based on levels achieved during the
performance test. A source must establish separate mercury feedrate
limits for each feed location. As previously discussed in this section,
for feedstreams where mercury is not present at detectable levels, the
feedrate limit must be defined as ``nondetect at the full detection
limit''.
There is no regulatory requirement for a source to achieve a given
detection limit under this approach. We acknowledge, however, that
feedstream detection limits can be high enough such that a mercury
feedrate limit that is based on nondetect performance test results may
not completely ensure compliance with the emission standard during day-
to-day operations. For example, the LWAK industry has indicated that a
hazardous waste mercury detection limit of 2 ppm is reasonably
achievable at an on-site laboratory. If we assume that mercury is
present in the hazardous waste at a concentration of 1.99 ppm (just
below the detection limit), the expected mercury emission concentration
would be approximately 80 g/dscm, which is above the
standard.203 (Note also that this does not consider mercury
emission contributions from the raw material.) This is not to say that
this LWAK will be exceeding the mercury emission standard during day-
to-day operations. However, their inability to achieve low mercury
detection limits results in less assurance that the source is
continuously complying with the emission standard.
---------------------------------------------------------------------------
\203\ This assumes that all the mercury fed to the unit is
emitted, and is based on typical LWAK gas emission rates.
---------------------------------------------------------------------------
The regulatory official should consider such emission standard
compliance assurance concerns when reviewing the waste analysis plan to
determine if lower detection limits are appropriate (if, in fact such
lower detection limits are reasonably achievable). Factors that should
be considered in this review should include: (1) The costs associated
with achieving lower detection limits; and (2) the estimated maximum
mercury concentrations that can occur if the source's feedstreams
contain mercury just below the detection limit (as described above).
C. Which Continuous Emissions Monitoring Systems Are Required in the
Rule?
Although the final rule does not require you to use continuous
emissions monitoring systems (CEMS) for parameters other than carbon
monoxide, hydrocarbon, oxygen, and particulate matter 204 we
have a strong preference for CEMS because they: (1) Are a direct
measure of the hazardous air pollutant or surrogate for which we have
established emission standards; (2) lead to a high degree of certainty
regarding compliance assurance; and (3) allow the public to be better
informed of what a source's emissions are at any time. Additionally,
from a facility standpoint, CEMs provide you with real time feedback on
your combustion operations and give you a greater degree of process
control. Therefore, we encourage you to use CEMS for other parameters
such as total mercury, multimetals, hydrochloric acid, and chlorine
gas. You may use the alternative monitoring provision of Sec. 63.8(f)
to petition the Administrator (i.e., permitting officials) to use CEMS
to document compliance with the emission standards in lieu of emissions
testing and the operating parameter limits specified in Sec. 63.1209.
You may submit the petition at any time, such as with the comprehensive
performance test plan. See Section VII.C.5.c below for a discussion of
the incentives for using CEMS.
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\204\ The final rule requires that particulate matter CEMS be
installed, but defers the effective date of the requirement to
install, calibrate, maintain, and operate PM CEMS until these
actions can be completed.
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In this section, we discuss the status of development of particular
CEMS and provide guidance on issues that pertain to case-by-case
approval of CEMS in lieu of compliance using operating parameter limits
and periodic emissions testing. Key issues include appropriate CEMS
performance specifications, reference methods for determining the
performance of CEMS, averaging periods, and temporary waiver of
emission standards if necessary to enable sources to correlate
particulate matter CEMS to the reference method.
1. What Are the Requirements and Deferred Actions for Particulate
Matter CEMS?
In the April 1996 NPRM, we proposed the use of particulate matter
CEMS to document compliance with the particulate matter emission
standards. Particulate matter CEMS are used for compliance overseas
205, but are not yet a regulatory compliance tool in the
U.S. Concurrent with this proposal, we undertook a demonstration of
particulate matter CEMS at a hazardous waste incinerator to determine
if these CEMS were feasible in U.S. applications. We selected the test
incinerator as representative of a worst-case application for a
particulate matter CEMS at any hazardous waste
[[Page 52926]]
combustor. It was important to document feasibility of the CEMS at a
worst-case application to minimize time and resources needed to
determine whether the CEMS were suitable for compliance assurance at
all hazardous waste combustors.
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\205\ The EU guidelines for hazardous waste combustion state
that particulate matter is a parameter for which compliance must be
documented continuously. In addition, proposals from vendors that we
received in response to our February 27, 1996 NODA (see 61 FR 7262)
indicate that there are many installations elsewhere overseas where
particulate matter CEMS are used for compliance assurance.
---------------------------------------------------------------------------
We published preliminary results of our CEMS testing and sought
comment on our approach to demonstrating particulate matter CEMS in the
March 1997 NODA. We then revised our approach and sought comment on the
final report in the December 1997 NODA. The December 1997 NODA also
clarified several issues that came to light during the demonstration
test pertaining to the manual reference method, particulate matter
CEMS, and general quality assurance issues. These clarifications were
embodied in a new manual method, Method 5-I (Method 5i), a revision to
the proposed Performance Specification 11 for particulate matter CEMS,
and a new quality assurance procedure, Procedure 2.
We believe that our tests adequately demonstrate that particulate
matter CEMS are a feasible, accurate, and reliable technology that can
and should be used for compliance assurance. In addition, preliminary
analyses of the cost of PM CEMS applied to hazardous waste combustors
suggest that these costs are reasonable. Accordingly, the final rule
contains a requirement to install PM CEMS. However, we agree with
comments that indicate a need to develop source-specific performance
requirements for particulate matter CEMS and to resolve other
outstanding technical issues. These issues include all questions
related to implementation of the particulate matter CEMS requirement
(i.e. relation to all other testing, monitoring, notification, and
recordkeeping), relation of the particulate matter CEMS requirement to
the PM emission standard, as well as technical issues involving
performance, maintenance and correlation of the particulate matter CEMS
itself. These issues will be addressed in a subsequent rulemaking.
Therefore, we defer the effective date of this requirement pending
further testing and additional rulemaking.
As a result, in today's final rule, we require that particulate
matter CEMS be installed at all hazardous waste burning incinerators,
cement kilns, and lightweight aggregate kilns. However, since we have
not finalized the performance specifications for the use of these
instruments or resolved some of the technical issues noted above, we
are deferring the effective date of the requirement to install,
calibrate, maintain and operate particulate matter CEMS until these
actions can be completed. The particulate matter CEMS installation
deadline will be established through future rulemaking, along with
other pertinent requirements, such as final Performance Specification
11, Appendix F Procedure 2. Finally, it should be noted that EPA has a
concurrent rulemaking process underway for nonhazardous waste burning
cement kilns and plans to adopt the same approach in that rule.
2. What Are the Test Methods, Specifications, and Procedures for
Particulate Matter CEMS?
a. What Is Method 5i? We promulgate in the final rule a new manual
method for measuring particulate matter, Method 5i. See appendix A to
part 60. We first published this new method in the December 1997 NODA.
One outgrowth of these particulate matter CEMS demonstration tests is
that we made significant improvements in making low concentration
Method 5 particulate measurements. We first discussed these
improvements in the preliminary report released in the March 1997 NODA,
and commenters to that NODA ask that these improvements be documented.
We documented these improvements by creating Method 5i.
We incorporated the following changes to Method 5 into Method 5i:
Improved sample collection; minimization of possible contamination;
Improved sample analysis; and an overall emphasis on elimination of
systemic errors in measurement. These improvement achieved significant
improvements in method accuracy and precision at low particulate matter
concentrations, relative to Method 5.
We are promulgating Method 5i today, in advance of any particulate
matter CEMS requirement, for several reasons. We expect this new method
will be preferred in all cases where low concentration (i.e., below 45
mg/dscm (0.02 gr/dscf) 206) measurements are
required for compliance with the standard. Given that all incinerators,
nearly all lightweight aggregate kilns, and some cement kilns are
likely to have emissions lower than 45 mg/dscm, we expect that Method
5i will become the particulate method of choice for most hazardous
waste combustors. In addition, we expect that Method 5i will be used to
correlate manual method results to particulate matter CEMS outputs for
those sources that elect to petition the Administrator to use a CEMS in
lieu of operating parameter limits for compliance assurance with the
particulate matter standard.207 This is because, unlike the
worst-case particulate matter measurements normally used to verify
compliance with the standard, low (or lower than normal) concentration
particulate matter data are required to develop a good correlation
between the CEMS output and the manual, reference method.
---------------------------------------------------------------------------
\206\ As noted later in the text, the filter and assembly used
for Method 5i is smaller than the one used for Method 5. This means
that the Method 5i filter plugs more easily than the one used for
Method 5. This issue becomes important at particulate matter
concentrations above 45 mg/dscm, or 0.02 gr/dscf.
\207\ As alluded to previously, sources may elect to use a CEMS
to comply with the numerical value of the particulate matter
emission standard on a six-hour rolling average in lieu of complying
with operating parameter limits specified by Sec. 63.1209(m).
---------------------------------------------------------------------------
Many of the issues commenters raise relate to how Method 5i should
be used to correlate particulate matter CEMS outputs to manual method
measurements. Even though we are deferring a CEMS requirement, we
address several key issues here given that sources may elect to
petition the Administrator under Sec. 63.8(f) to use a CEMS. This
discussion may provide a better understanding on our thinking on
particulate matter CEMS issues. In addition, certain comments are
specific to how Method 5i is performed. These comments and our
responses are relevant even if you use Method 5i only as a stack
particulate method and not to correlate a particulate matter CEMS to
the reference method.
i. Why Didn't EPA Validate Method 5i Against Method 5? Several
commenters recommend that we perform a full Method 301 validation to
confirm that Method 5i is equivalent to Method 5. We determined that a
full Method 301 validation is not necessary because the differences in
the two methods do not constitute a major change in the way particulate
samples are collected from an operational or an analytical standpoint.
We validated the filter extraction and weighting process--the only
modification from Method 5 (see ``Particulate Matter CEMS Demonstration
Test Final Report,'' Appendix A, in the Technical Support Document
208) `` and documented that Method 5i gives nearly identical
results as Method 5. Therefore, we disagree with the commenters'
underlying concern and conclude that Method 5i has been validated.
---------------------------------------------------------------------------
\208\ See USEPA, ``Final Technical Support Document for
Hazardous Waste Combustor MACT Standards, Volume IV: Compliance With
the Hazardous Waste Combustor Standards,'' July 1999.
---------------------------------------------------------------------------
ii. When Are Paired Trains Required? We have included in Method 5i
a requirement that paired trains must be
[[Page 52927]]
used to increase method precision. This requirement applies whether you
use Method 5i to demonstration compliance with the emission standard or
to correlate a particulate matter CEMS. In addition, if you elect to
petition the Administrator for approval to use a particulate matter
CEMS and elect to use Method 5 to correlate the CEMS, you must also
obtain paired Method 5 data to improve method precision and, thus, the
correlation.
During our CEMS testing, we collected particulate matter data using
two simultaneously-conducted manual method sampling trains. We called
the results from these simultaneous runs ``paired data.'' We discussed
the use of paired trains in the December 1997 NODA as being optional
but requested comment on whether we should require paired trains, state
a strong preference for them, or be silent on the issue. Many
commenters believe paired trains should be used at all times so
precision can be documented. With these comments in mind, and
consistent with our continued focus on the collection of high quality
emission measurements, we include a requirement in Method 5i to obtain
paired data. Method 5i also includes a minimum acceptable relative
standard deviation between these data pairs. As discussed below, both
data in the pair are rejected if the data exceed the acceptable
relative standard deviation.
To improve the correlation between the manual method and a
particulate matter CEMS, we also recommend that sources electing to use
Method 5 also obtain paired Method 5 data. Again, data sets that exceed
an acceptable relative standard deviation, as discussed below, should
be rejected. This recommendation will be implemented during the
Administrator's review of your petition requesting use a particulate
matter CEMS. If you elect to correlate the CEMS using Method 5, you are
expected to include in your petition a statement that you will obtain
paired data and will conform with our recommended relative standard
deviation for the paired data.
iii. What Are the Procedures for Identifying Outliers? We have
established maximum relative standard deviation values for paired data
for both Method 5i and Method 5. If a data pair exceed the relative
standard deviation, the pair is identified as an outlier and is not
considered in the correlation of a particulate matter CEMS with the
reference method. In addition, Method 5i pairs that exceed the relative
standard deviation are considered outliers and cannot be used to
document compliance with the emission standard.
In the initial phase of our CEMS tests, we established a procedure
for eliminating imprecise data. This consisted of eliminating a set of
paired data if the data disagree by more than some previously
established amount. Two identical methods running at the same time
should yield the same result; if they do not, the precision of both
data is suspect. Commenters agree with the need to identify and
eliminate imprecise data to enhance method precision. This is an
especially important step when comparing manual particulate matter
measurements to particulate matter CEMS measurements. As a result, we
include criteria in Method 5i to ensure data precision.
When evaluating the particulate matter CEMS Demonstration Test
data, we screened the data to remove these precision outliers. Data
outliers at that time were defined as paired data points with a
relative standard deviation 209 of greater than 30 percent.
We developed this 30% criterion by analyzing historical Method 5 data.
Several commenters, including a particulate matter CEMS vendor with
extensive European experience with correlation programs, recommend that
we tighten the relative standard deviation criteria. We concur, because
Method 5i is more precise than Method 5 given the improvements
discussed above. Therefore, one would logically expect a reasonable
precision criterion such as the relative standard deviation derived
from Method 5i data to be less than a similarly reasonable one derived
from Method 5 data. We investigated the particulate matter CEMS
Demonstration Test data base as well other available Method 5i data
(such as the data from a test program recently conducted at another US
incinerator). We conclude that a 10% relative standard deviation for
particulate matter emissions greater than or equal to 10 mg/dscm,
increased linearly to 25% for concentrations down to 1 mg/dscm, is a
better representation of acceptable, precise Method 5i paired data
210. Data obtained at concentrations lower than 1 mg/dscm
have no relative standard deviation limit.
---------------------------------------------------------------------------
\209\ RSD, or ``relative standard deviation'', is a
dimensionless number greater than zero defined as the standard
deviation of the samples, divided by the mean of the samples. In the
special case where only 2 data represent the sample, the mathematics
of determining the relative standard deviation simplifies greatly to
|CA-CB |/(CA + CB),
where CA and CB are the concentration results
from the two trains that represent the pair.
\210\ See Chapter 11, Section 2 of the technical background
document for details on the statistical procedures used to derive
these benchmarks: USEPA, ``Final Technical Support Document for
Hazardous Waste Combustor MACT Standards, Volume IV: Compliance With
the Hazardous Waste Combustor Standards,'' July 1999.
---------------------------------------------------------------------------
The relative standard deviation criterion for Method 5 data used
for particulate matter CEMS correlations continues to be 30%.
iv. Why Didn't EPA Issue Method 5i as Guidance Rather than
Promulgating It as a Method? Most commenters state that Method 5i
should be guidance rather than a published method and it should not be
a requirement for performing particulate matter CEMS correlation
testing or documenting compliance with the emission standard. In
particular, several commenters in the cement kiln industry express
concern over the limitations of Method 5i regarding the mass of
particulate it could collect. This section addresses these concerns.
We have promulgated Method 5i as a method because it provides
significant improvement in precision and accuracy of low level
particulate matter measurements relative to Method 5. Consequently,
although Method 5i is not a required method, we expect that permitting
officials will disapprove comprehensive performance test plans that
recommend using Method 5 for low level particulate levels. Further, we
expect that petitions to use a particulate matter CEMS that recommend
performance acceptance criteria (e.g., confidence level, tolerance
level, correlation coefficient) based on correlating the CEMS with
Method 5 measurements will be disapproved. This is because we expect
the CEMS to be able to achieve better acceptance criteria values using
Method 5i (because it is more accurate and precise than Method 5), and
expect better relative standard deviation between test pairs (resulting
in lower cost of correlation testing because fewer data would be
screened out as outliers).
Given that we expect and want widespread use of Method 5i, and to
ensure that its key provisions are followed, it is appropriate to
promulgate it as a method rather than guidance. If the procedure were
issued only as guidance, the source or stack tester could choose to
omit key provisions, thus negating the benefits of the method.
Relative to the direct reference in Method 5i that the method is
``most effective for total particulate matter catches of 50 mg or
less,'' this means the method is most effective at hazardous waste
combustors with particulate matter emissions below approximately 45 mg/
dscm (0.02 gr/dscf). This applicability statement is not
intended to be a bright line; total train catches exceeding 50 mg would
not invalidate
[[Page 52928]]
the method. Rather, we include this guidance to users of the method to
help them determine whether the method is applicable for their source.
Note that this statement is found in the applicability section of the
method, rather than the method description sections that follow. As
such, the reference is clearly an advisory statement, not a quality
assurance criterion. Total train catches above 50 mg are acceptable
with the method and the results from such trains can be used to
document compliance with the emission standard and for correlating
CEMS. But, users of Method 5i are advised that problems (such as
plugging of the filter) may arise when emissions are expected to exceed
45 mg/dscm. 211
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\211\ Stack testers have developed ways to deal with plugging of
a filter. Many stack testers simply remove the filter before it
plugs, install a new, clean filter, and continue the sampling
process where they left off with the old filter. The mass gain is
then the total mass accumulated on all filters during the run.
However, using multiple filters for a single run takes more time,
not only to install the new filter but also to condition and weigh
multiple filters for a single run. For Method 5i, it would also
involve more capital cost because the stack tester would need more
light-weight filter assemblies to perform the same number of runs.
For these reasons and even though the situation can be acceptably
managed, it is impractical to have the filter plug. This led to our
recommendation that Method 5i is best suited for particulate matter
(i.e., filter) loadings of at most 50 mg, or stack concentrations of
less than 45 mg/dscm (roughly 0.02 gr/dscf).
---------------------------------------------------------------------------
v. What Additional Costs Are Associated with Method 5i? Commenters
raise several issues regarding the additional costs of performing
Method 5i testing relative to using Method 5. There is an added cost
for the purchase of new Method 5i filter housings. These new
lightweight holders are the key addition to the procedure needed to
improve precision and accuracy and represent a one-time expense that
emission testing firms or sources that perform testing in-house will
have to incur to perform Method 5i. We do not view this cost as
significant and conclude that the use of a light-weight filter housing
is a reasonable and appropriate feature of the method.
Other commenters suggest that the requirement for pesticide-grade
acetone in the version of Method 5i contained in the December 1997 NODA
unnecessarily raises the cost of performing the method. Instead, they
ask us to identify a performance level for the acetone instead of a
grade requirement because it would allow test crews to meet that
performance in the most economical manner. We agree that prescribing a
certain type of acetone may unnecessarily increase costs and removed
the requirement for pesticide-grade acetone. Accordingly, the same
purity requirements cited in Method 5 for acetone are maintained for
Method 5i. The prescreening of acetone purity in the laboratory prior
to field use, consistent with present Method 5 requirements, is also
maintained in Method 5i.
Commenters make similar cost-related comments relative to the
requirement for Teflon beakers. At the request of several
commenters, we have expanded the requirement for Teflon
beakers to allow the use of beakers made from other similar light-
weight materials. Because materials other than Teflon can
be used to fabricate light-weight breakers, changing the requirement
from a technology basis to a performance basis will reduce costs while
achieving the performance goals of the method.
There were no significant comments regarding the added cost of
paired-train testing.
vi. What Is the Practical Quantification Limit of the Method 5i
Filter Sample? We received several comments related to the minimum
detection limit of Method 5i, including: the minimum sample required,
guidance on how long to sample, what mass should ideally be collected
on any filter, and the practical quantification limit.
Commenters are concerned that while we address the maximum amount
of particulate matter the method could handle, we are silent on the
issue of what minimum sample is required. This is important because
analytical errors, such as weighing of the filters, tend to have the
same error value associated with it irrespective of the mass loading.
To address this concern, Method 5i provides guidance on determining the
minimum mass of the collected sample based on estimated particulate
matter concentrations.
Related to the particulate mass collection issue is the issue of
how long a user of Method 5i needs to sample in order to an adequate
amount of particulate on the filter. The amount of particulate matter
collected is directly related to time duration of the sampling period,
i.e., the longer one samples, the more particulate is collected and
vice-versa. Therefore, Method 5i provides guidance on selecting a
suitable sampling time based on the estimated concentration of the gas
stream.
Both these issues directly relate to how much particulate matter
should ideally be collected on any individual filter. Our experience
indicates a minimum target mass is 10 to 20 mg.
Finally, we conclude that the targeted practical quantification
limit for Method 5i is 3.0 mg of sample. Discussion of how this
quantification limit is determined is highly technical and beyond the
scope of this preamble. See the technical support document for more
details.212
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\212\ See USEPA, ``Final Technical Support Document for
Hazardous Waste Combustor MACT Standards, Volume IV: Compliance With
the Hazardous Waste Combustor Standards,'' July 1999.
---------------------------------------------------------------------------
vii. How Are Blanks Used with Method 5i? Several commenters
question the use of acetone blanks or made recommendations for
additional blanks. We clarify in this section the collection and use of
sample blank data.
We recognize that high blank results can adversely effect the
analytical results, especially at low particulate matter
concentrations. To avoid the effect high blank results can have on the
analytical results, today's Method 5i adopts a strategy similar to
several of the organic compound test procedures (such as Method 23 in
part 60 and Method 0010 in SW-846) that require collection of blanks
but do not permit correction to the analytical results. Collection and
analysis of blanks remains an important component in the sampling and
analysis process for documenting the quality of the data, however. If a
test run has high blank results, the data may be suspect. Permitting
officials will address this issue on a case-by-case basis.
The importance of minimizing contamination is stressed throughout
Method 5i for both sample handling and use of high purity sample media.
If proper handling procedures are observed, we expect that the blank
values will be less than the method detection limit or within the value
for constant weight determination (0.5 mg). Therefore, the allowance
for blank correction that is provided in Method 5 is not permitted in
Method 5i. The method also recommends several additional types of
blanks to provide further documentation of the integrity and purity of
the acetone throughout the duration of the field sampling program.
b. What Is the Status of Particulate Matter CEMS Performance
Specification 11 and Quality Assurance/Quality Control Procedure 2? We
are not finalizing proposed Performance Specification 11 and Quality
Assurance/Quality Control Procedure 2 because the final rule does not
require the use of particulate matter CEMS. We considered stakeholder
comments on these documents, however, and have incorporated many
comments into the current drafts. We plan to publish these documents
when we address the particulate matter CEMS requirement. In the
interim, we will make them available as guidance to sources that are
[[Page 52929]]
considering the option of using a particulate matter CEMS to document
compliance.
c. How Have We Resolved Other Particulate Matter CEMS Issues? In
this section we discuss two additional issues: (1) Why didn't we
require continuous opacity monitors for compliance with the particulate
matter standard for incinerators and lightweight aggregate kilns; and
(2) can high correlation emissions testing runs exceed the particulate
matter standard?
i. Why Didn't We Require Continuous Opacity Monitors for Compliance
Assurance for Incinerators and Lightweight Aggregate Kilns? As
discussed elsewhere in today's notice, we require cement kilns to use
continuous opacity monitors (COMS) to comply with a 20 percent opacity
standard to ensure compliance with the particulate matter emission
standard. This is the opacity component of the New Source Performance
Standard for particulate matter for Portland cement plants. See
Sec. 60.62. Because we are adopting the mass-based portion of the New
Source Performance Standard for particulate matter as the MACT standard
(i.e., 0.15 kg/Mg dry feed), the opacity component of the New Source
Performance Standard is useful for compliance assurance.
We do not require that incinerators and lightweight aggregate kilns
use opacity monitors for compliance assurance because we are not able
to identify an opacity level that is achievable by sources using MACT
control and that would ensure compliance with the particulate matter
standards for these source categories. This is the same issue discussed
above in the context of particulate matter CEMS and is the primary
reason that we are not requiring use of these CEMS at this time.
Although we are requiring that cement kilns use COMS for compliance
assurance, these monitors cannot provide the same level of compliance
assurance as particulate matter CEMS. Opacity monitors measure a
characteristic of particulate matter (i.e., opacity) and cannot
correlate with the manual stack method as well as a particulate matter
CEMS. COMS are particularly problematic for sources with small stack
diameters (e.g., incinerators) and low emissions because both of these
factors contribute to very low opacity readings which results in high
measurement error as a percentage of the opacity value. Thus, we are
obtaining additional data to support rulemaking in the near future to
require use of particulate matter CEMS for compliance assurance.
Approximately 80 percent of hazardous waste burning cement kilns
are not currently subject to the New Source Performance Standard and
many of these sources may not be equipped with COMS that meet
Performance Specification 1 in appendix B, part 60. Thus, many
hazardous waste burning cement kilns will be required to install COMS,
even though we intend to require use of particulate matter CEMS in the
near future. We do not believe that this requirement will be overly
burdensome, however, because sources may request approval to install
particulate matter CEMS rather than COMS. See Sec. 63.8(f). Our testing
of particulate matter CEMS at a cement kiln will be completed well
before sources need to make decisions on how best to comply with the
COMS requirement of the rule. We will develop regulations and guidance
on performance specifications and correlation criteria for particulate
matter CEMS as a result of that testing, and sources can use that
guidance to request approval to use a particulate matter CEMS in lieu
of a COMS. We expect that most sources will elect to use this approach
to minimize compliance costs over the long term.
ii. Can High Correlation Runs Exceed the Particulate Matter
Standard? The final rule states that the particulate matter and opacity
standards of parts 60, 61, 63, 264, 265, and 266 (i.e., all applicable
parts of Title 40) do not apply during particulate matter CEMS
correlation testing, provided that you comply with certain provisions
discussed below that ensure that the provision is not abused. This
provision, as the rest of the rule, is effective immediately. Thus, you
need not wait for the compliance date to take advantage of this
particulate matter CEMS correlation test provision.
We include this provision in the rule because many commenters
question whether high correlation test runs that exceed the particulate
matter emission standard constitute noncompliance with the standard. We
have responded to this concern previously by stating that a single
manual method test run that exceeds the standard does not constitute
noncompliance with the standard because compliance is based on the
average of a minimum of three runs.213 We now acknowledge,
however, that during high run correlation testing a source may need to
exceed the emission standard even after averaging emissions across
runs. Similarly, a source may need to exceed a particulate matter
operating parameter limit. Given the benefits of compliance assurance
using a CEMS, we agree with commenters that short-term excursions of
the particulate matter standard or operating parameter limits for the
purpose of CEMS correlation testing is warranted. The benefits that a
CEMS provides for compliance assurance outweighs the short-term
emissions exceedances that may occur during high end emissions
correlation testing. Consequently, we have included a conditional
waiver of the applicability of all Federal particulate matter and
opacity standards (and associated operating parameter limits).
---------------------------------------------------------------------------
\213\ One exception is the destruction and removal efficiency
standard, for which compliance is based on a single test run and not
the average of three runs.
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The waiver of applicability of the particulate matter and opacity
emission standards and associated operating parameter limits is
conditioned on the following requirements to ensure that the waiver is
not abused. Based on information from commenters and expertise gained
during our testing, the rule requires that you develop and submit to
permitting officials a particulate matter CEMS correlation test plan
along with a statement of when and how any excess emissions will occur
during the correlation tests (i.e., how you will modify operating
conditions to ensure a wide range of particulate emissions, and thus a
valid correlation test). If the permitting officials fail to respond to
the test plan in 30 days, you can proceed with the tests as described
in the test plan. If the permitting officials comment on the plan, you
must address those comments and resubmit the plan for approval.
In addition, runs that exceed any particulate matter or opacity
emission standard or operating parameter limit are limited to no more
than a total of 96 hours per correlation test (i.e., including all runs
of all test conditions). We determined that the 96 hour total duration
for exceedances for a correlation test is reasonable because it is
comprised of one day to increase emissions to the desired level and
reach system equilibrium, two days of testing 214 at the
equilibrium condition followed by a return to normal equipment settings
indicative of compliance with emissions standards and operating
parameter limits, and one
[[Page 52930]]
day to reach equilibrium at normal conditions. Finally, to ensure these
periods of high emissions are due to the bona fide need described here,
a manual method test crew must be on-site and making measurements (or
in the event some unforseen problem develops, prepared to make
measurements) at least 24 hours after you make equipment or workplace
modifications to increase particulate matter emissions to levels of the
high correlation runs.
---------------------------------------------------------------------------
\214\ The two days assumes sources will conduct a total of 18
runs, 6 runs in each of the low, medium, and high particulate matter
emission ranges. To approve use of a particulate matter CEMS, we
will likely require that a minimum of 15 runs comprise a correlation
test. If this is the case, some runs will likely be eliminated
because they fail method or source-specific quality assurance/
quality control procedures.
---------------------------------------------------------------------------
3. What Is the Status of Total Mercury CEMS?
We are not requiring use of total mercury CEMS in this rulemaking
because data in hand do not adequately demonstrate nationally that
these CEMS are reliable compliance assurance tools at all types of
facilities. Nonetheless, we are committed to the development of CEMS
that measure total mercury emissions and are continuing to pursue the
development of these CEMS in our research efforts.
In the April 1996 NPRM, we proposed that total mercury CEMS be used
for compliance with the mercury standards. We also said if you elect to
use a multimetals CEMS that passed proposed acceptability criteria, you
could use that CEMS instead of a total mercury CEMS to document
compliance with the mercury standard. Finally, we indicated that if
neither mercury nor multimetal CEMS were required in the final rule
(i.e., because they have not been adequately demonstrated), compliance
assurance would be based on specified operating parameter limits.
In the March 1997 NODA, we elicited comment on early aspects of our
approach to demonstrate total mercury CEMS. And, in the December 1997
NODA, we presented a summary of the demonstration test results and our
preliminary conclusion that we were unable to adequately demonstrate
total mercury CEMS at a cement kiln, a site judged to be a reasonable
worst-case for performance of the total mercury CEMS. As new data are
not available, we continue to adhere to this conclusion, and comments
received in response to the December 1997 NODA concur with this
conclusion. Therefore, we are not requiring total mercury CEMS in this
rulemaking.
Nonetheless, the current lack of data to demonstrate total mercury
CEMS at a cement kiln or otherwise on a generic bases (i.e., for all
sources within a category) does not mean that the technology, as
currently developed, cannot be shown to work at particular sources.
Consequently, the final rule provides you the option of using total
mercury CEMS in lieu of complying with the operating parameter limits
of Sec. 63.1209(l). As for particulate matter and other CEMS, the rule
allows you to petition the Administrator (i.e., permitting officials)
under Sec. 63.8(f) to use a total mercury CEMS based on documentation
that it can meet acceptable performance specifications, correlation
acceptance criteria (i.e., correlation coefficient, tolerance level,
and confidence level). Although we are not promulgating the proposed
performance specification for total mercury CEMS (Performance
Specification 12) given that we were not able to document that a
mercury CEMS can meet the specification in a (worst-case) cement kiln
application, the proposed specification may be useful to you as a point
of departure for a performance specification that you may recommend is
achievable and reasonable.
4. What Is the Status of the Proposed Performance Specifications for
Multimetal, Hydrochloric Acid, and Chlorine Gas CEMS?
We are not promulgating proposed Performance Specifications 10, 13,
and 14 for multimetal, hydrochloric acid, and chlorine gas CEMS because
we have not determined that the CEMS can achieve the specifications.
In the April 1996 NPRM, we proposed performance specifications for
multimetal, hydrochloric acid, and chlorine gas CEMS to allow sources
to use these CEMS for compliance with the metals and hydrochloric acid/
chlorine gas standards. Given that we have not demonstrated that these
CEMS can meet their performance specifications and our experience with
a mercury CEMS where we were not able to demonstrate that the mercury
CEMS could meet our proposed performance specification, we are not
certain that these CEMS can meet the proposed performance
specifications. Accordingly, it would be inappropriate to promulgate
them.
As discussed previously, we encourage sources to investigate the
use of CEMS and to petition permitting officials under Sec. 63.8(f) to
obtain approval to use them. The proposed performance specifications
may be useful to you as a point of departure in your efforts to
document performance specifications that are achievable and that ensure
reasonable correlation with reference manual methods.
5. How Have We Addressed Other Issues: Continuous Samplers as CEMS,
Averaging Periods for CEMS, and Incentives for Using CEMS?
a. Are Continuous Samplers a CEMS? Several commenters, mostly
owner/operators of on-site incinerators, suggest that we should adjust
certain CEMS criteria (e.g., averaging period, response time) to allow
use of a continuous sampler known as the 3M Method. The 3M Method is a
continuous metals sampling system. It automatically extracts stack gas
and accumulates a sample on a filter medium over any desired period--24
hours, days, or weeks. The sample is manually extracted, analyzed, and
reported. Various incinerator operators are using or have expressed an
interest in using this type of approach to demonstrate compliance with
current RCRA metals emission limits. Many commenters contend that the
3M Method is a CEMS and that we developed our performance
specifications for CEMS to exclude techniques like the 3M Method.
After careful analysis, we conclude that the 3M Method is not a
CEMS. It does not meet our long-standing definition of a CEMS in parts
60 or 63. Specifically, it is not a fully automated piece(s) of
equipment used to extract a sample, condition and analyze the sample,
and report the results of the analysis in the units of the standard.
Also, the 3M Method is unable to ``complete a minimum of one cycle of
operation (sampling, analyzing, and data recording) for each successive
15-minute period'' as required by Sec. 63.8(c)(4)(ii). As a result,
making the subtle changes (e.g., to the averaging period, response
time) to our multimetal CEMS performance specification that commenters
recommend would not alter the fact that the device does not
automatically analyze the sample on the frequency required for a CEMS.
A continuous sampler (coupled with periodic analysis of the sample)
is inferior to a CEMS for two reasons. First, if the sampling period is
longer than the time it takes to perform three manual performance
tests, compliance with the standard cannot be assured. Approaches like
the 3M Method tend to have reporting periods on the order of days,
weeks, or even a month. The reporting period is comprised of the time
required to accumulate the sample and the additional time to analyze
the sample and report results. Because the stringency of a standard is
a function of both the numerical value of the standard and the
averaging period (e.g., at a given numerical limit, the longer the
averaging period the less stringent the standard), a compliance
approach having a sampling period greater than the 12 hours we estimate
it may take to conduct three manual method stack test runs using Method
29 cannot ensure
[[Page 52931]]
compliance with the standard.215 If the sampling period were
greater than the time required to conduct three test runs, the
numerical value of the standard would have to be reduced to ensure an
equally stringent standard. Unfortunately, we do not know how to derive
alternative emission limits as a function of the averaging period that
would be equivalent to the emission standard. We raised this issue at
proposal, and commenters did not offer a solution.
---------------------------------------------------------------------------
\215\ A technical support document for the February 1991
municipal waste combustor rule contains a good description of how
not only the numerical limit, but the averaging period as well,
determines the overall stringency of the standard. See Appendices A
and B found in ``Municipal Waste Combustion: Background Information
for Promulgated Standards and Guidelines--Summary of Public Comments
and Responses Appendices A to C'', EPA-450/3-91-004, December 1990.
---------------------------------------------------------------------------
Second, the results from a continuous sampler are reported after
the fact, resulting in higher excess emissions than with a CEMS.
Depending on the sample analysis frequency, it could take days or weeks
to determine that an exceedance has occurred and that corrective
measures need to be taken. A CEMS can provide near real-time
information on emissions such that exceedances can be avoided or
minimized.
Absent the generic availability of multimetal CEMS, continuous
samplers such as the 3M Method may nonetheless be a valuable compliance
tool. We have acknowledged that relying on operating parameter limits
may be an imperfect approach for compliance assurance. Sampling and
analysis of feedstreams to determine metals feedrates can be
problematic given the complexities of some waste matrices. In addition,
the operating parameters for the particulate matter control device for
which limits must be established may not always correlate well with the
device's control efficiency for metals and thus metals emissions.
Because of these concerns, we encourage sources to investigate the
feasibility of multimetal CEMS. But, absent a CEMS, a continuous
sampler may provide an attractive alternative or complement to some of
the operating parameter limits under Secs. 63.1209 (l) and (n). You may
petition permitting officials under Sec. 63.8(f) to use the 3M Method
(or other sampler) as an alternative method of compliance with the
emissions standards. Permitting officials will balance the benefits of
a continuous sampler with the benefits of the operating parameter
limits on a case-by-case basis.
b. What Are the Averaging Periods for CEMS and How Are They
Implemented? We discuss the following issues in this section: (1)
Duration of the averaging period; (2) frequency of updating the
averaging period; and (3) how averaging periods are calculated
initially and under intermittent operations.
i. What Is the Duration of the Averaging Period? We conclude that a
six-hour averaging period is most appropriate for particulate matter
CEMS, and a 12-hour averaging period is most appropriate for total
mercury, multi metals, hydrogen chloride, and chlorine gas CEMS.
We proposed that the averaging period for CEMS (i.e., other than
carbon monoxide, hydrocarbon, and oxygen) be equivalent to the time
required to conduct three runs of the comprehensive performance test
using manual stack methods. As discussed above and at proposal, we
proposed this approach because, to ensure compliance with the standard,
the CEMS averaging period must be the same as the time required to
conduct the performance test.216
---------------------------------------------------------------------------
\216\ Actually, the CEMS averaging period can be no longer than
the time required to conduct three runs of the performance test to
ensure compliance with the standard. Although compliance with the
standard would be ensured if the CEMS averaging period were less
than the time required to conduct the performance test, this
approach would be overly stringent because it would ensure
compliance with an emission level lower than the standard.
---------------------------------------------------------------------------
Commenters suggest two general approaches to establish averaging
periods for CEMS: technology-based and risk-based. Commenters
supporting a technology-based approach favor our proposed approach and
rationale where the time duration of three emissions tests would be the
averaging period for CEMS. Commenters favoring a risk-based approach
state that the averaging period should be years rather than hours
because the risk posed by emissions at levels of the standard were not
found to be substantial, assuming years of exposure. We disagree with
this rationale. CEMS are an option (that sources may request under
Sec. 63.8(f)) to document compliance with the emission standard. As
discussed above, if the averaging period for CEMS were longer than the
duration of the comprehensive performance test, we could not ensure
that a source maintains compliance with the standards.
Establishing an averaging period based on the time to conduct three
manual method stack test runs is somewhat subjective. There is no fixed
sampling time for manual methods--sampling periods vary depending on
the amount of time required to ``catch'' enough sample. Thus, we have
some discretion in selecting an averaging period using this approach.
Commenters generally favor longer averaging periods as an incentive for
using CEMS (i.e., because a limit is less stringent if compliance is
based on a long versus short averaging period). We agree that choosing
a longer averaging period would provide an incentive for the use of
CEMS, but conclude that the selected averaging period must be within
the range (i.e., high end) of times required to perform the three stack
test runs.
We derive the averaging period for particulate matter CEMS as
follows. Most particulate matter manual method tests are one hour in
duration, but a few stack sampling companies sample for longer periods,
up to two hours. Therefore, we use the high end of the range of values,
2 hours, as the basis for calculating the averaging period. We
recommend a six-hour rolling average considering that it may require 2
hours to conduct each of three stack tests.
For mercury, multi-metals, hydrochloric acid, and chlorine gas
CEMS, we recommend a 12-hour rolling averaging. The data base we used
to determine the standards shows that the sampling periods for manual
method tests for these standards ranged from one to four hours.
Choosing the high end of the range of values, 4 hours, as the basis for
calculating the averaging period, we conclude that a 12-hour rolling
average would be appropriate.
ii. How Frequently Is the Rolling Average Updated? We conclude that
the rolling average for particulate matter, total mercury, and
multimetal CEMS should be updated hourly, while the rolling average for
hydrochloric acid and chlorine gas CEMS should be updated each minute.
We proposed that all rolling averages would be updated every minute
and would be based on the average of the one-minute block average CEMS
observations that occurred over the averaging period. This proposed
one-minute update is the same that is used for carbon monoxide and
total hydrocarbon CEMS under the RCRA BIF regulations. (We are
retaining that update frequency in the final rule for those monitors,
and recommend it for hydrochloric acid and chlorine gas CEMS.)
Commenters favor selecting the frequency of updating the rolling
average taking into account the variability of the CEMS and limitations
concerning how the correlation data are collected. We agree with this
approach, as discussed below.
1. Particulate Matter CEMS. Commenters said that particulate matter
CEMS correlation tests are approximately one hour in duration and, if
the rolling average were updated
[[Page 52932]]
each minute, the CEMS would observe more variability in emissions
within this one hour than the manual method (which is an average of
those emissions during the hour). For this reason, we conclude it is
reasonable that particulate matter CEMS data be recorded as a block-
hour and that the rolling average be updated every hour as the average
of the previous six block-hours. Updating the particulate matter CEMS
every hour also means the number of compliance opportunities is the
same irrespective of whether a light-scattering or beta-gage
particulate matter CEMS is used (i.e., because beta-gage CEMS make
observations periodically while light-scattering CEMS make observations
continuously).
Furthermore, to ensure consistency with existing air rules
governing CEMS other than opacity, a valid hour should be comprised of
four or more equally spaced measurements during the hour. See
Sec. 60.13(h). This means that batch systems, such as beta gages, must
complete one cycle of operation every 15 minutes, or more frequently if
possible. See Sec. 63.8(c)(4)(ii). CEMS that produce a continuous
stream of data, such as light-scattering CEMS, will produce data
throughout the hour.
You may not be able to have four valid 15-minute measurement in an
hour, however, to calculate an hourly block-average. Examples include
when the source shuts down or the CEMS produces flagged (i.e.,
problematic) data. In addressing this issue, we balanced the need for
the average of the measurements taken during the hour to be
representative of emissions during the hour with the need to
accommodate problems with data availability that will develop. We
conclude that a particulate matter CEMS needs to sample stack gas and
produce a valid result from this sample for most of the hour. This
means that the CEMS needs to be observing stack gas at least half (30
minutes, or two 15-minute cycles of operation) of the block-hour.
Emissions from less than one hour might be unrepresentative of
emissions during the hour, and on balance we conclude that this
approach is reasonable. If a particulate matter CEMS does not sample
stack gas and produce a valid result from that sample for at least 30
minutes of a given hour, the hour is not a valid block-hour. In
documenting compliance with the data availability recommendation in the
draft performance specification, invalid block-hours due to
unavailability of the CEMS that occur when the source is in operation
count against data availability. If the hour is not valid because the
source was not operating for more than 30 minutes of the hour, however,
the invalid block-hour does not count against the data availability
recommendation.217
---------------------------------------------------------------------------
\217\ Data availability is defined as the fraction, expressed as
a percentage, of the number of block-hours the CEMS is operational
and obtaining valid data during facility operations, divided by the
number of block-hours the facility was operating.
---------------------------------------------------------------------------
2. Total Mercury and Multimetal CEMS. As discussed for particulate
matter CEMS, we also expect manual methods will be required to
correlate total mercury and multimetal CEMS prior to using them for
compliance. For the reasons discussed above in the context of
particulate matter CEMS, we therefore recommend the observations from
these CEMS be recorded as block-hour averages and that the 12-hour
rolling average be updated every hour based on the average of the
previous 12 block-hour averages.
3. Hydrochloric Acid and Chlorine Gas CEMS. Unlike the particulate
matter, total mercury, and multimetal CEMS, hydrochloric acid and
chlorine gas CEMS are likely to be calibrated using Protocol 1 gas
bottles rather than correlated to manual method stack test results.
Therefore, the variability of observations measured by the CEMS over
some averaging period versus the duration of a stack test is not an
issue. We conclude that it is appropriate to update the 12-hour rolling
average for these CEMS every minute, as required for carbon monoxide
and hydrocarbons CEMS.
iii. How Are Averaging Periods Calculated Initially and under
Intermittent Operations?
1. Practical Effective Date of Rolling Averages for CEMS. As
discussed in Part Five, Sections VII.B.4 above in the context of
continuous monitoring systems in general, CEMS recordings will not
become effective for compliance monitoring on the compliance date until
you have recorded enough observations to calculate the rolling average
applicable to the CEMS. For example, the six hourly rolling average for
particulate matter CEMS does not become effective until you have
recorded six block-hours of observations on the compliance date. Given
that compliance with the standards begins nominally at 12:01 am on the
compliance date, the six hour rolling average for particulate matter
CEMS does not become effective as a practical matter until 6:01 am on
the compliance date. Similarly, the 12-hour rolling average for a
multimetal CEMS does not become effective until you have recorded 12
block-hours of observations after the compliance date. Thus, the 12-
hour rolling average for multimetals CEMS becomes effective as a
practical matter at 12:01 p.m. on the compliance date.
We adopt this approach simply because a rolling average does not
exist until enough observations have been recorded to calculate the
rolling average.
2. How Rolling Averages Are Calculated Upon Intermittent
Operations. We have determined that you are to ignore periods of time
when CEMS observations are not recorded for any reason (e.g., source
shutdown) when calculating rolling averages. For example, consider how
the six hour rolling average for a particulate matter CEMS would be
calculated if a source shuts down for yearly maintenance for a three
week period. The first one-hour block average value recorded when the
source renews operations is added to the last 5 one-hour block averages
recorded before the source shut down for maintenance to calculate the
six hour rolling average.
We adopt this approach for all continuous monitoring systems,
including CEMS, because it is simple and reasonable. See discussion in
Part Five, Section B.4 above.
c. What Are the Incentives for Using CEMS as Alternative
Monitoring? We strongly support the use of CEMS for compliance with
standards, even though we are not requiring their use in today's rule
(except for carbon monoxide, hydrocarbon, and oxygen CEMS) for the
reasons discussed above. We endorse the principle that, as technology
advances, current rules should not act as an obstacle to adopting new
CEMS technologies for compliance. For instance, today's rule does not
require total mercury CEMS because implementation and demonstration
obstacles observed during our tests under what we consider worst-case
conditions (i.e., a cement kiln) could not be resolved in sufficient
time to require total mercury CEMS at all hazardous waste combustors.
However, we fully expect total mercury CEMS will improve to the point
that the technical issues encountered in our tests can be resolved. At
that point, we do not want the compliance regime of today's rule--
comprised of emissions testing and limits on operating parameters--to
be so rigid as to preclude the use of CEMS. Commenters are generally
supportive of this concept, but note that facilities would be reluctant
to adopt new technologies without adequate incentives. This section
describes potential incentives: emissions testing would not be
required; limits on operating parameters would not apply while the CEMS
is in service; and the feedstream analysis requirements for the
[[Page 52933]]
parameters measured by the CEMS (i.e., metals or chlorine) would not
apply.
i. What Incentives Do Commenters Suggest? Several commenters
suggest that we provide various incentives to encourage development and
implementation of new and emerging CEMS. Comments by the Coalition for
Responsible Waste Incineration (CRWI) include a variety of actions to
encourage voluntary installation of CEMS,218 including:
Reduce testing for any parameter measured by a CEMS to the correlation
and maintenance of that CEMS; waive operating parameter limits that are
linked to the pollutant measured by the CEMS; minimize regulatory
oversight on waste analysis if compliance is consistently demonstrated
by a CEMS; increase the emission limit for a source using a CEMS to
account for the uncertainty of CEMS observations; allow a phase-in
period when a source can evaluate CEMS performance and develop
maintenance practices and the CEMS would not be used for compliance;
allow a phase-in period to establish a reasonable availability
requirement for that CEMS at a particular location; and allow sources
to evaluate CEMS on a trial basis to determine if these instruments are
appropriate for their operations with no penalties if the units do not
work or have excessive downtime. Many of CRWI's suggestions have merit,
as discussed below.
---------------------------------------------------------------------------
\218\ By ``optional use of CEMS'', we mean using CEM not
required by this rule, i.e., other than those for carbon monoxide,
oxygen, and hydrocarbon.
---------------------------------------------------------------------------
ii. How Do We Respond to Commenter's Recommended Incentives?
1. Waiver of Emissions Testing and Operating Parameter Limits.
CRWI's first two suggestions (reduced testing and waiver of operating
parameter limits) are closely linked. The purpose of conducting a
comprehensive performance test is to document compliance with emission
standard initially (and periodically thereafter) and establish limits
on specified operating parameters to ensure that compliance is
maintained. Because a CEMS ensures compliance continuously, it serves
the purpose of both the performance test and compliance with operating
parameter limits. Accordingly, we agree with CRWI that both emissions
testing and operating parameter limits for the pollutant in question
would not apply to sources using a CEMS.
There is one key caveat to this position, however. Because 100%
availability of any CEMS is unrealistic, we require a means of assuring
compliance with the emission standards during periods when the CEMS is
not available. To meet that need, you may elect to install redundant
CEMS or assure continuous compliance by monitoring and recording
traditional operating parameter limits during periods when the CEMS is
not available. Most likely, you will elect to use operating parameters
as the back-up when the CEMS is unavailable because it would be a less
expensive approach. You could establish these operating parameter
limits, though, through CEMS measurements rather than comprehensive
performance test measures. In fact, it may be prudent for you to
evaluate relationships between various operating parameters for the
particulate matter control device 219 and emission levels
recorded by the CEMS to develop a good predictive model of emissions.
You could then petition the Administrator (i.e., permitting officials)
under Sec. 63.8(f) to base compliance during CEMS malfunctions on
limits on alternative monitoring parameters derived from the predictive
model.
---------------------------------------------------------------------------
\219\ You are not restricted to those specified in Sec. 63.1209.
You may identify parameters for your source that correlate better
with particulate emissions than those we have specified generically.
---------------------------------------------------------------------------
2. Waiver of Feedstream Analysis Requirements. If you obtain
approval to use a CEMS for compliance under the petitioning provisions
of Sec. 63.8(f), we agree with the commenter's recommendation that you
should not be subject to the feedstream analysis requirements pertinent
to the pollutant you are measuring with a CEMS. As examples, if you use
a total mercury CEMS, you are not subject to a feedrate limit for
mercury, and if you operate an incinerator and use a particulate matter
CEMS, you are not subject to a feedrate limit for total ash.
If you are not subject to a feedrate limit for ash, metals, or
chorine because you use a CEMS for compliance, you are not subject to
the feedstream analysis requirements for these materials. As a
practical matter, however, this waiver may be moot because, as
discussed above, you will probably elect to comply with operating
parameter limits during CEMS malfunctions. However, a second, back-up
CEMS would also be acceptable. Absent a second CEMS, you would need to
establish feedrate limits for these materials as a back-up compliance
approach, and you would need to know the feedrate at any time given
that the CEMS may malfunction at any time. In addition, even when the
CEMS is operating within the performance specifications approved by the
permitting officials, you have the responsibility to minimize
exceedances by, for example, characterizing your feedstreams adequately
to enable you to take corrective measures if a CEMS-monitored emission
is approaching the standard. This level of feedstream characterization,
however, is less than the characterization required to establish and
comply with feedrate operating limits during CEMS malfunctions or
absent a CEMS.
3. Increase the Averaging Period for CEMS-Monitored Pollutants. The
averaging period for a CEMS-monitored pollutant should not be
artificially inflated (i.e., increased beyond the time required to
conduct three manual method test runs) because the standard would be
less stringent. See previous discussions on this issue.
4. Increase Emission Limits to Account for CEMS Uncertainty. We do
not agree with the suggestion that an emission limit needs to be
increased on a site-specific basis to accommodate CEMS inaccuracy and
imprecision (i.e., the acceptance criteria in the CEMS performance
specification that the source recommends and the permitting officials
approve will necessarily allow some inaccuracy and imprecision). Again,
we encourage sources to use a CEMS because it is a better indicator of
compliance than the promulgated compliance regime (i.e., periodic
emissions testing and operating parameter limits). We established the
final emission standards with achievability (through the use of the
prescribed compliance methods) in mind. We have accounted for the
inaccuracies and imprecisions in the emissions data in the process of
establishing the standard. See previous discussions in Part Four,
Section V.D. If the CEMS performance specification acceptance criteria
(that must be approved by permitting officials under a Sec. 63.8(f)
petition) were to allow the CEMS measurements to be more inaccurate or
imprecise than the promulgated compliance regime of performance testing
coupled with limits on operating parameters, the potential for improved
compliance assurance with the CEMS would be negated. Consequently, we
reject the idea that the standards need to be increased on a site-
specific basis as an incentive for sources to use CEMS.
5. Allow a CEMS Phase-In Period. CRWI's final three incentive
suggestions deal with the need for a CEMS phase-in period. This phase-
in period would be used to evaluate CEMS performance, including
identifying acceptable performance specification levels, maintenance
requirements, and measurement location. CRWI further suggested that the
Agency not penalize
[[Page 52934]]
a source if the CEMS does not work or has excessive downtime.
CRWI provided these comments in response to our proposal to require
compliance using CEMS and that sources document that the CEMS meets a
prescribed performance specification and correlation acceptance
criteria. Although we agree that a phase-in period would be
appropriate, the issue is moot given that we are not requiring the use
of CEMS.220 Prior to submitting a petition under
Sec. 63.8(f) to gain approval to use a CEMS, we presume a source will
identify the performance specification, correlation criteria, and
availability factors they believe are achievable. (We expect sources to
use the criteria we have proposed, as revised after considering
comments and further analysis and provided through guidance, as a point
of departure.) Thus, each source will have unlimited opportunity to
phase-in CEMS and subsequently recommend under Sec. 63.8(f) performance
specifications and correlation acceptance criteria.
---------------------------------------------------------------------------
\220\ Other than carbon monoxide, hydrocarbon, and oxygen CEMS.
---------------------------------------------------------------------------
We do not agree as a legal matter that we can state generically
that CEMS data obtained during the demonstration period are shielded
from enforcement if the CEMS data are credible and were to indicate
exceedance of an emission standard. In this situation, we cannot shield
a source from action by either by a regulatory agency or a citizen
suit. On balance, given our legal constraints, our policy desire to
have CEMS used for compliance, and uncertainty about the ultimate
accuracy of the CEMS data, we can use our enforcement discretion
whether to use particulate matter CEMS data as credible evidence in the
event the CEMS indicates an exceedance until the time the CEMS is
formally adopted as a compliance tool. Sources and regulators may
decide to draft a formal testing agreement that states that the CEMS
data obtained prior to the time the CEMS is accepted as a compliance
tool cannot be used as credible evidence of exceedance of an emission
standard.
D. What Are the Compliance Monitoring Requirements?
In this section we discuss the operating parameter limits that
ensure compliance with each emission standard.
1. What Are the Operating Parameter Limits for Dioxin/Furan?
You must maintain compliance with the dioxin/furan emission
standard by establishing and complying with limits on operating
parameters. See Sec. 63.1209(k). The following table summarizes these
operating parameter limits. All sources must comply with the operating
parameter limits applicable to good combustion practices. Other
operating parameter limits apply if you use the dioxin/furan control
technique to which they apply.
BILLING CODE 6560-50-P
[[Page 52935]]
[GRAPHIC] [TIFF OMITTED] TR30SE99.000
[[Page 52936]]
[GRAPHIC] [TIFF OMITTED] TR30SE99.001
BILLING CODE 6560-50-C
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Dioxin/furan emissions from hazardous waste combustors are
primarily attributable to surface-catalyzed formation reactions
downstream from the combustion chamber when gas temperatures are in the
450 deg.F to 650 deg.F window (e.g., in an electrostatic precipitator
or fabric filter; in extensive ductwork between the exit of a
lightweight aggregate kiln and the inlet to the fabric filter; as
combustion gas passes through an incinerator waste heat recovery
boiler). In addition, dioxin/furan partition in two phases in stack
emissions: a portion is adsorbed onto particulate matter and a portion
is emitted as a vapor (gas). Because of these factors, and absent a
CEMS for dioxin/furan, we are requiring a combination of approaches to
control dioxin/furan emissions: (1) Temperature control at the inlet to
a dry particulate matter control device to limit dioxin/furan formation
in the control device; (2) operation under good combustion conditions
to minimize dioxin/furan precursors and dioxin/furan formation during
combustion; and (3) compliance with operating parameter limits on
dioxin/furan emission control equipment (e.g., carbon injection) that
you may elect to use.
We discuss below the operating parameter limits that apply to each
dioxin/furan control technique.
a. Combustion Gas Temperature Quench. To minimize dioxin/furan
formation in a dry particulate matter control device that suspends
collected particulate matter in the gas flow (e.g., electrostatic
precipitator, fabric filter), the rule limits the gas temperature at
the inlet to these control devices 221 to levels occurring
during the comprehensive performance test. For lightweight aggregate
kilns, however, you must monitor the gas temperature at the kiln exit
rather than at the inlet to the particulate matter control device. This
is because the dioxin/furan emission standard for lightweight aggregate
kilns specifies rapid quench of combustion gas to 400 deg.F or less at
the kiln exit. 222
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\221\ The temperature at the inlet to a cyclone separator used
as a prefiltering process for removing larger particles is not
limited. Cyclones do not suspend collected particulate matter in the
gas stream. Thus, these devices do not have the same potential to
enhance dioxin/furan formation as electrostatic precipitators and
fabric filters.
\222\ As discussed in Part Four, Section VIII, lightweight
aggregate kilns can have extensive ducting between the kiln exit and
the inlet to the fabric filter. If gas temperatures are limited at
the inlet to the fabric filter, substantial dioxin/furan formation
could occur in the ducting.
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If your combustor is equipped with a wet scrubber as the initial
particulate matter control device, you are not required to establish
limits on combustion gas temperature at the scrubber. This is because
wet scrubbers do not suspend collected particulate matter in the gas
stream and gas temperatures are well below 400 deg.F in the
scrubber.223 Thus, scrubbers do not enhance surface-
catalyzed formation reactions.
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\223\ For this reason, you are not required to document during
the comprehensive performance test that gas temperatures in the wet
scrubber are not greater than 400 deg.F. Also, we note that the 400
deg.F temperature limit of the dioxin/furan standard does not apply
to wet scrubbers, but rather to the inlet to a dry particulate
matter control device and the kiln exit of a lightweight aggregate
kiln.
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We proposed limits on the gas temperature at the inlet to a dry
particulate matter control device (see 61 FR at 17424). Temperature
control at this location is important because surface-catalyzed
formation reactions can increase by a factor of 10 for every 150 deg.F
increase in temperature within the window of 350 deg.F to
approximately 700 deg.F. We received no adverse comments on the
proposal, and thus, are adopting this compliance requirement in the
final rule.
You must establish an hourly rolling average temperature limit
based on operations during the comprehensive performance test. The
hourly rolling average limit is established as the average of the test
run averages. See Part Five, Sections VII.B.1 and B.3 above for a
discussion on the approach for calculating limits from comprehensive
performance test data.
b. Good Combustion Practices. All hazardous waste combustors must
use good combustion practices to control dioxin/furan emissions by: (1)
Destroying dioxin/furan that may be present in feedstreams; (2)
minimizing formation of dioxin/furan during combustion; and (3)
minimizing dioxin/furan precursor that could enhance post-combustion
formation reactions. As proposed, you must establish and continuously
monitor limits on three key operating parameters that affect good
combustion: (1) Maximum hazardous waste feedrate; (2) minimum
temperature at the exit of each combustion chamber; and (3) residence
time in the combustion chamber as indicated by gas flowrate or kiln
production rate. We have also determined that you must establish
appropriate monitoring requirements to ensure that the operation of
each hazardous waste firing system is maintained. We discuss each of
these parameters below.
i. Maximum Hazardous Waste Feedrate. You must establish and
continuously monitor a maximum hazardous waste feedrate limit for
pumpable and nonpumpable wastes. See 61 FR at 17422. An increase in
waste feedrate without a corresponding increase in combustion air can
cause inefficient combustion that may produce (or incompletely destroy)
dioxin/furan precursors. You must also establish hazardous waste
feedrate limits for each location where waste is fed.
One commenter suggests that there is no reason to limit the
feedrate of each feedstream; a limit on the total hazardous waste
feedrate to each combustion chamber would be a more appropriate control
parameter. We concur in part. Limits are not established for each
feedstream. Rather, limits apply to total and pumpable wastes feedrates
for each feed location. Limits on pumpable wastes are needed because
the physical form of the waste can affect the rate of oxygen demand and
thus combustion efficiency. Pumpable wastes often will expose a greater
surface area per mass of waste than nonpumpable wastes, thus creating a
more rapid oxygen demand. If that demand is not satisfied, inefficient
combustion will occur. We also note that these waste feedrate limit
requirements are consistent with current RCRA permitting requirements
for hazardous waste combustors.
As proposed, you must establish hourly rolling average limits for
hazardous waste feedrate from comprehensive performance test data as
the average of the highest hourly rolling averages for each run. See
Part Five, Section VII.B.3 above for the rationale for this approach
for calculating limits from comprehensive performance test data.
ii. Minimum Gas Temperature in the Combustion Zone. You must
establish and continuously monitor limits on minimum gas temperature in
the combustion zone of each combustion chamber irrespective of whether
hazardous waste is fed into the chamber. See 61 FR at 17422. These
limits are needed because, as combustion zone temperatures decrease,
combustion efficiency can decrease resulting in increased formation of
(or incomplete destruction of) dioxin/furan precursors.224
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\224\ See USEPA, ``Final Technical Support Document for
Hazardous Waste Combustor MACT Standards, Volume IV: Compliance with
the Hazardous Waste Combustor Standards'', February, 1999.
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Monitoring combustion zone temperatures can be problematic,
however, because the actual burning zone temperature cannot be measured
at many units (e.g., cement kilns). For this reason, the BIF rule
requires
[[Page 52938]]
measurement of the ``combustion chamber temperature where the
temperature measurement is as close to the combustion zone as
possible.'' See Sec. 266.103(c)(1)(vii). In some cases, temperature is
measured at a location quite removed from the combustion zone due to
extreme temperatures and the harsh conditions at the combustion zone.
We discussed this issue at proposal and indicated that we were
concerned that monitoring at such remote locations may not accurately
reflect changes in combustion zone temperatures. See 61 FR at 17423.
We requested comment on possible options to address the issue.
Under one option, the final rule would have allowed the source to
identify a parameter that correlates with combustion zone temperature
and to provide data or information to support the use of that parameter
in the operating record. Under another option, the final rule would
have enabled regulatory officials on a case-specific basis to require
the use of alternate parameters as deemed appropriate, or to determine
that there is no practicable approach to ensure that minimum combustion
chamber temperature is maintained (and what the recourse/consequence
would be).
Some commenters recommend the status quo as identified by the BIF
rule requirements for monitoring combustion zone temperature. These
commenters suggest that more prescriptive requirements would not be
implementable for cement kilns because use of the temperature
measurement instrumentation would simply not be practicable under
combustion zone conditions in a cement kiln. We agree that combustion
zone temperature monitoring for certain types of sources requires some
site-specific considerations (as evidenced in our second proposed
option discussed above), and conclude that more specific language than
that used in the BIF rule to address this issue would not be
appropriate. Accordingly, we adopt language similar to the BIF rule in
today's final rule. You must measure the temperature of each combustion
chamber at a location that best represents, as practicable, the bulk
gas temperature in the combustion zone of that chamber. You are
required to identify the temperature measurement location and method in
the comprehensive performance test plan, which is subject to Agency
approval.
The temperature limit(s) apply to each combustion zone, as
proposed. See 61 FR at 17423. For incinerators with a primary and
secondary chamber, you must establish separate limits for the
combustion zone in each chamber.225 For kilns, you must
establish separate temperature limits at each location where hazardous
waste may be fired (e.g., the hot end where clinker is discharged; and
the upper end of the kiln where raw material is fed). We also proposed
to include temperature limits for hazardous waste fired at the midkiln.
One commenter indicates that it is technically infeasible to measure
temperature directly at the midkiln waste feeding location, however. We
agree that midkiln gas temperature is difficult to measure due to the
rotation of the kiln.226 Thus, the final rule allows
temperature measurement at the kiln back-end as a surrogate.
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\225\ The temperature limits apply to a combustion chamber even
if hazardous waste is not burned in the chamber for two reasons.
First, an incinerator may rely on an afterburner that is fired with
a fuel other than hazardous waste to ensure good combustion of
organic compounds volatilized from hazardous waste in the primary
chamber. Second, MACT controls apply to total emissions (except
where the rule makes specific provisions), irrespective of whether
they derive from burning hazardous waste or other material, or from
raw materials.
\226\ See USEPA. ``Final Technical Support Document for
Hazardous Waste Combustor MACT Standards, Volume IV: Compliance with
the Hazardous Waste Combustor Standards'', February, 1999, for
further discussion.
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You must establish an hourly rolling average temperature limit
based on operations during the comprehensive performance test. The
hourly rolling average limit is established as the average of the test
run averages. See Part Five, Sections VII.B.1 and B.3 above for a
discussion on the approach for calculating limits from comprehensive
performance test data.
iii. Maximum Flue Gas Rate or Kiln Production Rate. As proposed,
you must establish and continuously monitor a limit on maximum flue gas
flowrate or, as a surrogate, kiln production rate. See 61 FR at 17423.
Flue gas flowrates in excess of those that occur during comprehensive
performance testing reduce the time that combustion gases are exposed
to combustion chamber temperatures. Thus, combustion efficiency can
decrease potentially causing an increase in dioxin/furan precursors
and, ultimately, dioxin/furan emissions.227
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\227\ We note that an increase in gas flowrate can also
adversely affect the performance of a dioxin/furan emission control
device (e.g., carbon injection, catalytic oxidizer). Thus, gas
flowrate is controlled for this reason as well.
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For cement kilns and lightweight aggregate kilns, the rule allows
the use of production rate as a surrogate for flue gas flowrate. This
is the approach currently used for the BIF rule for these devices,
given that flue gas flowrate correlates with production rate (e.g.,
feedrate of raw materials or rate of production of clinker or
aggregate).
At proposal, however, we expressed concern that production rate may
not relate well to flue gas flowrate in situations where the moisture
content of the feed to the combustor changes dramatically. See 61 FR at
17423. Some commenters concur and also express concern that production
rate is not a reliable surrogate for flue gas flowrate because changes
in ambient temperature can cause increased heat rates and changes in
operating conditions can result in variability in excess air rates.
Based on an analysis of kiln processes, however, we conclude that these
issues should not be a concern. With respect to changes in moisture
content of the feed, kilns tend to have a steady and homogeneous waste
and raw material processing system. Thus, the feed moisture content
does not fluctuate widely, and variation in moisture content of the
stack does not significantly affect gas flowrate.228 Thus,
production rate should be an adequate surrogate for gas flowrate for
our purposes here.
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\228\ See USEPA, ``Final TSD for hazardous Waste Combustor MACT
Standards, Volume IV: Compliance with the Hazardous Waste Combustor
Standards'', February, 1999 for further discussion.
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You must establish a maximum gas flowrate or production rate limit
as the average of the maximum hourly rolling averages for each run of
the comprehensive performance test. See Part Five, Sections VII.B.3
above for the rationale for the approach for calculating limits from
comprehensive performance test data.
iv. Operation of Each Hazardous Waste Firing System. You must
recommend in the comprehensive performance test plan that you submit
for review and approval operating parameters, limits, and monitoring
approaches to ensure that each hazardous waste firing system continues
to operate as efficiently as demonstrated during the comprehensive
performance test.
It is important to maintain operation of the hazardous waste firing
system at levels of the performance test to ensure that the same or
greater surface area of the waste is exposed to combustion conditions
(e.g., temperature and oxygen). Oxidation takes place more quickly and
completely as the surface area per unit of mass of the waste increases.
If the firing system were to degrade over time such that smaller
surface area is exposed to combustion conditions, inefficient
combustion could result leading potentially to an increase in dioxin/
furan precursors.
[[Page 52939]]
At proposal, we discussed establishing operating parameter limits
only for minimum nozzle pressure and maximum viscosity of wastes fired
using a liquid waste injection system. In developing the final rule,
however, we determined that RCRA permit writers currently establish
operating parameter limits on each waste firing system to ensure
compliance with the RCRA destruction and removal efficiency (DRE)
standard. We are continuing the DRE requirement as a MACT standard, and
as discussed in Section VII.D.7 below, the DRE operating parameter
limits are identical to those required to maintain good combustion
practices for compliance with the dioxin/furan standard. This is
because compliance with the DRE standard is ensured by maintaining good
combustion practices. Consequently, we include a requirement to
establish limits on operating parameters for each waste or fuel firing
system as a measure of good combustion practices for the dioxin/furan
standard as well to be technically correct and for purposes of
completeness.229 Because this requirement is identical to an
existing RCRA requirement, it will not impose an incremental burden.
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\229\ Because incomplete combustion of fuels (e.g., oil, coal,
tires) could contribute to increased dioxin/furan emissions by
producing dioxin/furan precursors, permitting official may require
(during review and approval of the comprehensive performance test
plan) that you establish limits on operating parameters for firing
systems in addition to those firing hazardous waste.
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The rule does not prescribe generic operating parameters and how to
identify limits because, given the variety of firing systems and waste
and fuel properties, they are better defined on a site-specific basis.
Examples of monitoring parameters for a liquid waste firing system
would be, as proposed, minimum nozzle pressure established as an hourly
rolling average based on the average of the minimum hourly rolling
averages for each run, coupled with a limit on maximum waste viscosity.
The viscosity limit could be monitored periodically based on sampling
and analysis. Examples of monitoring parameters for a lance firing
system for sludges could be minimum pressure established as discussed
above, plus a limit on the solids content of the waste.
v. Consideration of Restrictions on Batch Size, Feeding Frequency,
and Minimum Oxygen Concentration. We proposed site-specific limits on
maximum batch size, batch feeding frequency, and minimum combustion gas
oxygen concentration as additional compliance requirements to ensure
good combustion practices. See 61 FR at 17423. After carefully
considering all comments, and for the reasons discussed below, we
conclude that the carbon monoxide and hydrocarbon emission standards
assure use of good combustion practices during batch feed operations.
This is because the carbon monoxide and hydrocarbon CEMS are reliable
and continuous indicators of combustion efficiency. In situations where
batch feed operating requirements may be needed to better assure good
combustion practices, however, we rely on the permit writer's
discretionary authority under Sec. 63.1209(g)(2) to impose additional
operating parameter limits on a site-specific basis.
Many hazardous waste combustors burn waste fuel in batches, such as
metal drums or plastic containers. Some containerized waste can
volatilize rapidly, causing a momentary oxygen-deficient condition that
can result in an increase in emissions of carbon monoxide, hydrocarbon,
and dioxin/furan precursors. We proposed to limit batch size, batch
feeding frequency, and minimum combustion gas oxygen concentration to
address this concern.
Commenters suggest that the proposed batch feed requirements (that
would limit operations to the smallest batch, the longest time
interval, and the maximum oxygen concentration demonstrated during the
comprehensive performance test) would result in extremely conservative
limits that would severely limit a source's ability to batch-feed
waste. Given these concerns and our reanalysis of the need for these
limits, we conclude that the carbon monoxide and hydrocarbon emission
standards will effectively ensure good combustion practices for most
batch feed operations. Consequently, the final rule does not require
limits for batch feed operating parameters.
Carbon monoxide or hydrocarbon monitoring may not be adequate for
all batch feed operations, however, to ensure good combustion practices
are maintained. We anticipate that permitting officials will determine
on a site-specific basis, typically during review of the initial
comprehensive performance test plan, whether limits on one or more
batch feed operating parameters need to be established to ensure good
combustion practices are maintained. This review should consider your
previous compliance history (e.g., frequency of automatic waste feed
cutoffs attributable to batch feed operations that resulted in an
exceedance of an operating limit or standard under RCRA regulations
prior to the compliance date), together with the design and operating
features of the combustor. Providing permitting officials the authority
under Sec. 63.1209(g)(2) to establish batch feed operating parameter
limits only where warranted precludes the need to impose the limits on
all sources.
Permitting officials may also determine that limits on batch feed
operating parameters are needed for a particular source based on the
frequency of automatic waste feed cutoffs after the MACT compliance
date. Permitting officials would consider cutoffs that are attributable
to batch feed operations and that result in an exceedance of an
operating parameter limit or the carbon monoxide or hydrocarbon
emission standard. Given that you must notify permitting officials if
you have 10 or more automatic waste feed cutoffs in a 60-day period
that result in an exceedance of an operating parameter limit or CEMS-
monitored emission standard, permitting officials should take the
opportunity to determine if batch feed operations contributed to the
frequency of exceedances. If so, permitting officials should use the
authority under Sec. 63.1209(g)(2) to establish batch feed operating
parameter limits.
Although we are not finalizing batch feed operating parameter
limits, we anticipate that permitting officials will require you
(during review and approval of the test plan) to simulate worst-case
batch feed operating conditions during the comprehensive performance
test when demonstrating compliance with the dioxin/furan and
destruction and removal efficiency standards. It would be inappropriate
for you to operate your batch feed system during the comprehensive
performance test in a manner that is not considered worst-case,
considering the types and quantities of wastes you may burn, and the
range of values you may encounter during operations for batch feed-
related operating parameters (e.g., oxygen levels, batch size and/or
btu content, waste volatility, batch feeding frequency).
To ensure that the CEMS-monitored carbon monoxide and hydrocarbon
emission standards ensure good combustion practices for batch feed
operations, the final rule includes special requirements to ensure that
``out-of-span'' carbon monoxide and hydrocarbon CEMS readings are
adequately accounted for. We proposed batch feed operating parameter
limits in part because of concern that the carbon monoxide and
hydrocarbon CEMS may not accurately calculate hourly rolling averages
when you encounter emission concentrations that exceed the span of the
CEMS. This is an important
[[Page 52940]]
consideration because batch feed operations have the potential to
generate large carbon monoxide or hydrocarbon spikes--large enough at
times to exceed the span of the detector. When this occurs, the CEMS in
effect ``pegs out'' and the analyzer may only record data at the upper
end of its span, while in fact carbon monoxide/hydrocarbon
concentrations are much higher. In these situations, the true carbon
monoxide/hydrocarbon concentration is not being used to calculate the
hourly rolling average. This has two significant consequences of
concern to us.230
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\230\ As explained in Part Five, Section VII.D.4 of the text,
this concern is not limited to batch feed operations.
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First, you could experience a large carbon monoxide/hydrocarbon
spike (as a result of feeding a large or highly volatile batch) which
causes the monitor to ``peg out.'' In this situation, the CEMS would
record carbon monoxide/hydrocarbon levels that are lower than actual
levels. This under-reporting of emission levels would result in an
hourly rolling average that is biased low. You may in fact be exceeding
the emission standard even though the CEMS indicates you are in
compliance. Second, if a carbon monoxide/hydrocarbon excursion causes
an automatic waste feed cutoff, you may be allowed to resume hazardous
waste burning much sooner than you would be allowed if the CEMS were
measuring true hourly rolling averages. This is because you must
continue monitoring operating parameter limits and CEMS-monitored
emission standards after an automatic waste feed cutoff and you may not
restart hazardous waste feeding until all limits and CEMS-monitored
emission standards are within permissible levels.231
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\231\ A higher hourly rolling average carbon monoxide level that
is above the standard requires a longer period of time to drop below
the standard.
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As explained in Part Five, Section VII.D.4 below, we have resolved
these ``out of span'' concerns by including special provisions in
today's rule for instances when you encounter hydrocarbon/carbon
monoxide CEMS measurements that are above the upper span required by
the performance specifications.232 These special provisions
require you to assume hydrocarbons and carbon monoxide are being
emitted at levels of 500 ppmv and 10,000 ppmv, respectively, when any
one minute average exceeds the upper span level of the
detector.233 Although we did not propose these special
provisions, they are a logical outgrowth of the proposed batch feed
requirements and commenters concerns about those requirements.
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\232\ The carbon monoxide CEMS upper span level for the high
range is 3000 ppmv. The upper span level for hydrocarbon CEMS is 100
ppmv. (See Performance Specifications 4B and 8A in Appendix B, part
60, and the appendix to subpart EEE, part 63--Quality Assurance
Procedures for Continuous Emissions Monitors Used for Hazardous
Waste Combustors, Section 6.3).
\233\ You would not be required to assume these one-minute
values if you use a CEMS that meets the performance specifications
for a range that is higher than the recorded one-minute average. In
this case, the CEMS must meet performance specifications for the
higher range as well as the ranges specified in the performance
specifications in Appendix B, part 60. See Sec. 63.1209 (a)(3) and
(a)(4).
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For the reasons discussed above, we conclude that national
requirements for batch feed operating parameter limits are not
warranted.
c. Activated Carbon Injection. If your combustor is equipped with
an activated carbon injection system, you must establish and comply
with limits on the following operating parameters: Good particulate
matter control, minimum carbon feedrate, minimum carrier fluid flowrate
or nozzle pressure drop, and identification of the carbon brand and
type or the adsorption characteristics of the carbon. These are the
same compliance parameters that we proposed. See 61 FR at 17424.
i. Good Particulate Matter Control. You must comply with the
operating parameter limits for particulate matter control (see
discussion in Section VII.D.6 below and Sec. 63.1209(m)) because carbon
injection controls dioxin/furan in conjunction with particulate matter
control. Dioxin/furan is adsorbed onto carbon that is injected into the
combustion gas, and the carbon is removed from stack gas by a
particulate control device.
Although we proposed to require good particulate matter control as
a control technique for dioxin/furan irrespective of whether carbon
injection was used, commenters indicate that we have no data
demonstrating the relationship between particulate matter and dioxin/
furan emissions. Commenters further indicate that dioxin/furan occur
predominately in the gas phase, not adsorbed onto particulate. We agree
with commenters that hazardous waste combustors operating under the
good combustion practices required by this final rule are not likely to
have significant carbon particulates in stack gas (i.e., because
carbonaceous particulates (soot) are indicative of poor combustion
efficiency). Thus, unless activated carbon injection is used as a
control technique, dioxin/furan will occur predominately in the gas
phase. We therefore conclude that requiring good particulate control as
a control technique for dioxin/furan is not warranted unless a source
is equipped with activated carbon injection.234
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\234\ We discuss below, however, that good particulate matter
control is also required if a source is equipped with a carbon bed.
This is to ensure that particulate control upstream of the carbon
bed is maintained to performance test levels to prevent blinding of
the bed and loss of removal efficiency.
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ii. Minimum Carbon Feedrate. As proposed, you must establish and
continuously monitor a limit on minimum carbon feedrate to ensure that
dioxin/furan removal efficiency is maintained. You must establish an
hourly rolling average feedrate limit based on operations during the
comprehensive performance test. The hourly rolling average limit is
established as the average of the test run averages. See Part Five,
Sections VII.B.1 and B.3 above for a discussion of the approach for
calculating limits from comprehensive performance test data.
iii. Minimum Carrier Fluid Flowrate or Nozzle Pressure Drop. A
carrier fluid, gas or liquid, is necessary to transport and inject the
carbon into the gas stream. As proposed, you must establish and
continuously monitor a limit on either minimum carrier fluid flowrate
or pressure drop across the nozzle to ensure that the flow and
dispersion of the injected carbon into the flue gas stream is
maintained.
We proposed to require you to base the limit on the carbon
injection manufacturer's specifications. One commenter notes that there
are no manufacturer specifications for carrier gas flowrate or pressure
drop. Therefore, the final rule allows you to use engineering
information and principles to establish the limit for minimum carrier
fluid flowrate or pressure drop across the injection nozzle. You must
identify the limit and the rationale for deriving it in the
comprehensive performance test plan that you submit for review and
approval.
iv. Identification of Carbon Brand and Type or Adsorption
Properties. You must either identify the carbon brand and type used
during the comprehensive performance test and continue using that
carbon, or identify the adsorption properties of that carbon and use a
carbon having equivalent or better properties. This will ensure that
the carbon's adsorption properties are maintained.235
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\235\ Examples of carbon properties include specific surface
area, pore volume, average pore size, pore size distribution, bulk
density, porosity, carbon source, impregnation, and activization
procedure. See USEPA, ``Technical Support Document for HWC MACT
Standards, Volume IV: Compliance with the HWC MACT Standards,'' July
1999.
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We proposed to require you to use the same brand and type of carbon
that was
[[Page 52941]]
used during the comprehensive performance test. Commenters object to
this requirement and suggest that they should have the option of using
alternative types of carbon that would achieve equivalent or better
performance than the carbon used during the performance test. We
concur, and the final rule allows you to document in the comprehensive
performance test plan key parameters that affect adsorption and the
limits you have established on those parameters based on the carbon to
be used during the performance test. You may substitute at any time a
different brand or type of carbon provided that the replacement has
equivalent or improved properties and conforms to the key sorbent
parameters you have identified. You must include in the operating
record written documentation that the substitute carbon will provide
the same level of control as the original carbon.
d. Activated Carbon Bed. If your combustor is equipped with an
activated carbon bed, you must establish and comply with limits on the
following operating parameters: good particulate matter control;
maximum age of each carbon bed segment; identification of carbon brand
and type or adsorption properties, and maximum temperature at the inlet
or exit of the bed. These are the same compliance parameters that we
proposed. See 61 FR at 17424.
i. Good Particulate Matter Control. You must comply with the
operating parameter limits for particulate matter control (see
discussion in Section VII.D.6 below and Sec. 63.1209(m)). If good
control of particulate matter is not maintained prior to the inlet to
the carbon bed, particulate matter could contaminate the bed and affect
dioxin/furan removal efficiency. In addition, if particulate matter
control is used downstream from the carbon bed, those controls must
conform to good particulate matter control. This is because this
``polishing'' particulate matter control device may capture carbon-
containing dioxin/furan that may escape from the carbon bed. Thus, the
efficiency of this polishing control must be maintained to ensure
compliance with the dioxin/furan emission standard.
ii. Maximum Age of Each Bed Segment. As proposed, you must
establish a maximum age of each bed segment to ensure that removal
efficiency is maintained. Because activated carbon removes dioxin/furan
(and mercury) by adsorption, carbon in the bed becomes less effective
over time as the active sites for adsorption become occupied. Thus, bed
age is an important operating parameter.
At proposal, we requested comment on using carbon aging or some
form of a breakthrough calculation to identify a limit on carbon age.
See 61 FR at 17424. A breakthrough calculation would give a theoretical
minimum carbon change-out schedule that you could use to ensure that
breakthrough (i.e., the dramatic reduction in efficiency of the carbon
bed due to too many active sites being occupied) does not occur.
Commenters indicate that carbon effectiveness depends on the carbon
bed age and pollutant types and concentrations in the gas streams, and
therefore a carbon change-out schedule should be based on a
breakthrough calculation rather than carbon age. We agree that a
breakthrough calculation may be a better measurement of carbon
effectiveness, but it would be difficult to define generically for all
situations. A breakthrough calculation could be performed only after
experimentation determines the relationship between incoming adsorbed
chemicals and the adsorption rate of the carbon. The adsorption rate of
carbon could be determined experimentally, but the speciation of
adsorbed chemicals in a flue gas stream is site-specific and may vary
greatly at a given site over time.
We conclude that because carbon age contributes to carbon
ineffectiveness, it serves as an adequate surrogate and is less
difficult to implement on a national basis. Therefore, the rule
requires sources to identify maximum carbon age as the maximum age of
each bed segment during the comprehensive performance test. Carbon age
is measured in terms of the cumulative volume of combustion gas flow
through the carbon since its addition to the bed. Sources may use the
manufacturer's specifications rather than actual bed age during the
initial comprehensive performance test to identify the initial limit on
maximum bed age. If you elect to use manufacturer's specifications for
the initial limit on bed age, you must also recommend in the
comprehensive performance test plan submitted for review and approval a
schedule of dioxin/furan testing prior to the confirmatory performance
test that will confirm that the manufacturer's specification of bed age
is sufficient to ensure that you maintain compliance with the emission
standard.
If either existing or new sources prefer to use some form of
breakthrough calculation to establish maximum bed age, you may petition
permitting officials under Sec. 63.1209(g)(1) 236 to apply
for an alternative monitoring scheme.
---------------------------------------------------------------------------
\236\ We have incorporated the alternative monitoring provisions
of Sec. 63.8(f) in Sec. 63.1209(g)(1) so that alternative monitoring
provisions for nonCEMS CMS can be implemented by authorized States.
The alternative monitoring provisions of Sec. 63.1209(g)(1) do not
apply to CEMS, however. The alternative monitoring provisions of
Sec. 63.8(f) continue to apply to CEMS because implementation of
those provisions is not eligible to be delegated to States at this
time.
---------------------------------------------------------------------------
iii. Identification of Carbon Brand and Type or Adsorption
Properties. You must either identify the carbon brand and type used
during the comprehensive performance test and continue using that
carbon, or identify the adsorption properties of that carbon and use a
carbon having equivalent or better properties. This requirement is
identical to that discussed above for activated carbon injection
systems.
iv. Maximum Temperature at the Inlet or Exit of the Bed. You must
establish and continuously monitor a limit on the maximum temperature
at the inlet or exit of the carbon bed. This is because a combustion
gas temperature spike can cause adsorbed dioxin/furan (and mercury) to
desorb and reenter the gas stream. In addition, the adsorption
properties of carbon are adversely affected at higher temperatures.
At proposal, we requested comment on whether it would be necessary
to control temperature at the inlet to the carbon bed. See 61 FR at
17425. Some commenters support temperature control noting the concern
that temperature spikes could cause desorption of dioxin/furan (and
mercury). We concur, and are requiring you to establish a maximum
temperature limit at the inlet or exit of the bed. We are allowing you
the option of measuring temperature at either end of the bed to give
you greater flexibility in locating the temperature continuous
monitoring system. Monitoring temperature at either end of the bed
should be adequate to ensure that bed temperatures are maintained at
levels not exceeding those during the comprehensive performance test
(because the temperature remains relatively constant across the bed).
You must establish an hourly rolling average temperature limit
based on operations during the comprehensive performance test. The
hourly rolling average limit is established as the average of the test
run averages. See Part Five, Sections VII.B.1 and B.3 above for a
discussion of the approach for calculating limits from comprehensive
performance test data.
e. Catalytic Oxidizer. If your combustor is equipped with a
catalytic oxidizer, you must establish and comply with limits on the
following operating parameters: minimum gas temperature
[[Page 52942]]
at the inlet of the catalyst; maximum age in use; catalyst replacement
specifications; and maximum flue gas temperature at the inlet of the
catalyst. These are the same compliance parameters that we proposed.
See 61 FR at 17425.
Catalytic oxidizers used to control stack emissions are similar to
those used in automotive and industrial applications. The flue gas
passes over catalytic metals, such as palladium and platinum, supported
by an alumina washcoat on some metal or ceramic substrate. When the
flue gas passes through the catalyst, a reaction takes place similar to
combustion, converting hydrocarbons to carbon monoxide, then carbon
dioxide. Catalytic oxidizers can also be ``poisoned'' by lead and other
metals in the same manner as automotive and industrial catalysts.
i. Minimum Gas Temperature at the Inlet of the Catalyst. You must
establish and continuously monitor a limit on the minimum flue gas
temperature at the inlet of the catalyst to ensure that the catalyst is
above light-off temperature. Light-off temperature is that minimum
temperature at which the catalyst is hot enough to catalyze the
reactions of hydrocarbons and carbon monoxide.
You must establish an hourly rolling average temperature limit
based on operations during the comprehensive performance test. The
hourly rolling average limit is established as the average of the test
run averages.
ii. Maximum Time In-Use. You must establish a limit on the maximum
time in-use of the catalyst because a catalyst is poisoned and
generally degraded over use. You must establish the limit based on the
manufacturer's specifications.
iii. Catalytic Metal Loading, Maximum Space-Time, and Substrate
Construct. When you replace a catalyst, the replacement must be of the
same design to ensure that destruction efficiency is maintained.
Consequently, the rule requires that you specify the following catalyst
properties: Loading of catalytic metals; space-time; and monolith
substrate construction.
Catalytic metal loading is important because, without sufficient
catalytic metal on the catalyst, it does not function properly. Also,
some catalytic metals are more efficient than others. Therefore, the
replacement catalyst must have at least the same catalytic metal
loading for each catalytic metal as the catalyst used during the
comprehensive performance test.
Space-time, expressed in inverse seconds (s-1), is
defined as the maximum rated volumetric flow through the catalyst
divided by the volume of the catalyst. This is important because it is
a measure of the gas flow residence time and, hence, the amount of time
the flue gas is in the catalyst. The longer the gas is in the catalyst,
the more time the catalyst has to cause hydrocarbons and carbon
monoxide to react. Replacement catalysts must have the same or lower
space-time as the one used during the comprehensive performance test.
Substrate construction is also an important parameter affecting
destruction efficiency of the catalyst. Three factors are important.
First, substrates for industrial applications are typically monoliths,
made of rippled metal plates banded together around the circumference
of the catalyst. Ceramic monoliths and pellets can also be used.
Because of the many types of substrates, you must use the same
materials of construction, monolith or pellets and metal or ceramic,
used during the comprehensive performance test as replacements. Second,
monoliths form a honeycomb like structure when viewed from one end. The
pore density (i.e., number of pores per square inch) is critical
because the pores must be small enough to ensure intimate contact
between the flue gas and the catalyst but large enough to allow
unrestricted flow through the catalyst. Therefore, if you use a
monolith substrate during the comprehensive performance test, the
replacement catalyst must have the same pore density. Third, catalysts
are supported by a washcoat, typically alumina. We require that
replacement catalysts have the same type and loading of washcoat as was
on the catalyst used during the comprehensive performance test.
iv. Maximum Flue Gas Temperature at the Inlet to the Catalyst. You
must establish and continuously monitor a limit on maximum flue gas
temperature at the inlet to the catalyst. Inlet temperature is
important because sustained high flue gas temperature can result in
sintering of the catalyst, degrading its performance. You must
establish the limit as an hourly rolling average, based on manufacturer
specifications.
In the proposed rule, we would have allowed a waiver from these
operating parameter limits if you documented to the Administrator that
establishing limits on other operating parameters would be more
appropriate to ensure that the dioxin/furan destruction efficiency of
the oxidizer is maintained after the performance test. See 61 FR at
17425. We are not finalizing a specific waiver for catalytic oxidizer
parameters because you are eligible to apply for the same relief under
the existing alternative monitoring provisions of Sec. 63.1209(g)(1).
f. Dioxin/Furan Formation Inhibitor. If you feed a dioxin/furan
formation inhibitor into your combustor as an additive (e.g., sulfur),
you must: (1) Establish a limit on minimum inhibitor feedrate; and (2)
identify either the brand and type of inhibitor or the properties of
the inhibitor.
i. Minimum Inhibitor Feedrate. As proposed, you must establish and
continuously monitor a limit on minimum inhibitor feedrate to help
ensure that dioxin/furan formation reactions continue to be inhibited
at levels of the comprehensive performance test. See 61 FR at 17425.
You must establish an hourly rolling average feedrate limit based on
operations during the comprehensive performance test. The hourly
rolling average limit is established as the average of the test run
averages.
This minimum inhibitor feedrate pertains to additives to
feedstreams, not naturally occurring inhibitors that may be found in
fossil fuels, hazardous waste, or raw materials. At proposal, we
requested comment on whether it would be appropriate to establish
feedrate limits on the amount of naturally occurring inhibitors based
on levels fed during the comprehensive performance test. See 61 FR at
17425. For example, it is conceivable that a source would choose to
burn high sulfur fuel or waste only during the comprehensive
performance test and then switch back to low sulfur fuels or waste
after the test, thus reducing dioxin/furan emissions during the
comprehensive test to levels that would not be maintained after the
test. Commenters do not provide information on this matter and we do
not have enough information on the types or effects of naturally
occurring substances that may act as inhibitors. Therefore, the final
rule does not establish limits on naturally occurring inhibitors.
Permitting officials, however, may choose to address the issue of
naturally occurring inhibitors when warranted during review of the
comprehensive performance test plan. (See discretionary authority of
permitting officials under Sec. 63.1209(g)(2) to impose additional or
alternative operating parameter limits on a site-specific basis.)
ii. Identification of Either the Brand and Type of Inhibitor or the
Properties of the Inhibitor. As proposed, you must either identify the
inhibitor brand and type used during the comprehensive performance test
and continue using that inhibitor, or identify the properties of that
inhibitor that affect its ability to inhibit dioxin/furan formation
reactions and use an inhibitor having equivalent
[[Page 52943]]
or better properties. This requirement is identical to that discussed
above for activated carbon systems.
2. What Are the Operating Parameter Limits for Mercury?
You must maintain compliance with the mercury emission standard by
establishing and complying with limits on operating parameters. See
Sec. 63.1209(l). The following table summarizes these operating
parameter limits. All sources must comply with the limits on mercury
feedrate. Other operating parameter limits apply if you use the mercury
control technique to which they apply.
[GRAPHIC] [TIFF OMITTED] TR30SE99.002
Mercury emissions from hazardous waste combustors are controlled by
controlling the feedrate of mercury, wet scrubbing to remove soluble
mercury species (e.g, mercuric chloride), and carbon adsorption. We
discuss below the operating parameter limits that apply to each control
technique. We also discuss why we are not limiting the temperature at
the inlet to the dry particulate matter control device as a control
parameter for mercury.
a. Maximum Mercury Feedrate. As proposed, you must establish and
comply with a maximum total feedrate limit for mercury for all
feedstreams. See 61 FR at 17428. The amount of mercury fed into the
combustor directly affects emissions and the removal efficiency of
emission control equipment. To establish and comply with the feedrate
limit, you must sample and analyze and continuously monitor the
flowrate of all feedstreams (including hazardous waste, raw materials,
and other fuels and additives) except natural gas, process air, and
feedstreams from vapor recovery systems for mercury content.\237\ As
proposed, you must establish a maximum 12-hour rolling average feedrate
limit based on operations during the comprehensive performance test as
the average of the test run averages.
---------------------------------------------------------------------------
\237\ See discussion in Section VII.D.3. below in the text for
rationale for exempting these feedstreams for monitoring for mercury
content.
---------------------------------------------------------------------------
Rather than establish mercury feedrate limits as the levels fed
during the comprehensive performance test, you may request as part of
your performance test plan to use the mercury feedrates and associated
emission rates during the performance test to extrapolate to higher
allowable feedrate limits and emission rates. See Section VII.D.3 below
for a discussion of the rationale and procedures for obtaining approval
to extrapolate metal feedrates.
In addition, you may use the performance test waiver provision
under Sec. 63.1207(m) to document compliance with the emission
standard. Under that provision, you must monitor the total mercury
feedrate from all feedstreams and the gas flowrate and document that
the maximum theoretical emission concentration does not exceed the
mercury emission standard. Thus, this is another compliance approach
where you would not establish feedrate limits on mercury during the
comprehensive performance test.
b. Wet Scrubbing. As proposed, if your combustor is equipped with a
wet scrubber, you must establish and comply with limits on the same
operating parameters (and in the same manner) that apply to compliance
assurance with the hydrochloric acid/chlorine gas emission standard for
wet scrubbers. See Section VII.D.5 below for a discussion of those
parameters.
c. Activated Carbon Injection. As proposed, if your combustor is
equipped with an activated carbon injection system, you must establish
and comply with limits on the same operating parameters (and in the
same manner) that apply to compliance assurance with the dioxin/furan
emission standard for activated carbon injection systems.
d. Activated Carbon Bed. As proposed, if your combustor is equipped
with an activated carbon bed, you must establish and comply with limits
on the same operating parameters (and in the same manner) that apply to
compliance assurance with the dioxin/furan emission standard for
activated carbon beds.
e. Consideration of a Limit on Maximum Inlet Temperature to a Dry
Particulate Matter Control Device. The final rule does not require you
to control inlet temperature to a dry particulate
[[Page 52944]]
matter air pollution control device to control mercury emissions. At
proposal, we expressed concern that high inlet temperatures to a dry
particulate matter control device could cause low mercury removal
efficiency because mercury volatility increases with increasing
temperature. See 61 FR at 17428. Therefore, we proposed to limit inlet
temperatures to levels during the comprehensive performance test.
Commenters suggest that a maximum inlet temperature for dry
particulate matter control devices is not needed because mercury is
generally highly volatile within the range of inlet temperatures of all
dry particulate matter control devices. We are persuaded by the
commenters that inlet temperature to these devices is not critically
important to mercury control, although temperature can potentially have
an impact on the volatility of certain mercury species (e.g., oxides).
We conclude that the other operating parameter limits are sufficient to
ensure compliance with the mercury emission standard. In particular, we
note that a limit on maximum inlet temperature to these control devices
is required for compliance assurance with the dioxin/furan,
semivolatile metal, and low volatile metal emission standards.
3. What Are the Operating Parameter Limits for Semivolatile and Low
Volatile Metals?
You must maintain compliance with the semivolatile metal and low
volatile metal emission standards by establishing and complying with
limits on operating parameters. See Sec. 63.1209(n). The following
table summarizes these operating parameter limits. All sources must
comply with the limits on feedrates of semivolatile metals, low
volatile metals, and chlorine. Other operating parameter limits apply
depending on the type of particulate matter control device you use.
BILLING CODE 6560-50-P
[[Page 52945]]
[GRAPHIC] [TIFF OMITTED] TR30SE99.003
BILLING CODE 6560-50-C
[[Page 52946]]
Semivolatile and low volatile metal emissions from hazardous waste
combustors are controlled by controlling the feedrate of the metals and
particulate matter emissions. In addition, because chlorine feedrate
can affect the volatility of metals and thus metals levels in the
combustion gas, and because the temperature at the inlet to the dry
particulate matter control device can affect whether the metal is in
the vapor (gas) or solid (particulate) phase, control of these
parameters is also important to control emissions of these metals. We
discuss below the operating parameter limits that apply to each control
technique. We also discuss use of metal surrogates during performance
testing, provisions for allowing extrapolation of performance test
feedrate levels to calculate metal feedrate limits, and conditional
waiver of the limit on low volatile metals in pumpable feedstreams.
a. Good Particulate Matter Control. As proposed, you must comply
with the operating parameter limits for particulate matter control (see
discussion in Section VII.D.6 below and Sec. 63.1209(m)) because
semivolatile and low volatile metals are primarily in the solid
(particulate) phase at the gas temperature (i.e., 400 deg.F or lower)
of the particulate matter control device. Thus, these metals are
largely removed from flue gas as particulate matter.
b. Maximum Inlet Temperature to Dry Particulate Matter Control
Device. As proposed, you must establish and continuously monitor a
limit on the maximum temperature at the inlet to a dry particulate
matter control device. Although most semivolatile and low volatile
metals are in the solid, particulate phase at the temperature at the
inlet to the dry control device mandated by today's rule (i.e.,
400 deg.F or lower), some species of these metals remain in the vapor
phase. We are requiring a limit on maximum temperature at the inlet to
the control device to ensure that the fraction of these metals that are
volatile (and thus not controlled by the particulate matter control
device) does not increase during operations after the comprehensive
performance test.
As proposed, you must establish an hourly rolling average
temperature limit based on operations during the comprehensive
performance test. The hourly rolling average limit is established as
the average of the test run averages. See Part Five, Sections VII.B.1
and B.3 above for a discussion of the approach for calculating limits
from comprehensive performance test data.
Commenters suggest that this limit may conflict with the maximum
temperature limit at the inlet to the particulate matter control device
that is also required for compliance assurance with the dioxin/furan
emission standard. We do not understand commenters' concern. If for
some reason the dioxin/furan and metals emissions tests are not
conducted simultaneously, the governing temperature limit will be the
lower of the limits established from the separate tests. This provides
compliance assurance for both standards.
c. Maximum Semivolatile and Low Volatile Metals Feedrate Limits.
You must establish limits on the maximum total feedrate of both
semivolatile metals and low volatile metals from all feedstreams at
levels fed during the comprehensive performance test. Metals feedrates
are related to emissions in that, as metals feedrates increase at a
source, metals emissions increase. See Part Four, Section II.A above
for discussion on the relationship between metals feedrates and
emissions. Thus, metals feedrates are an important control technique.
For low volatile metals, you must also establish a limit on the
maximum total feedrate of pumpable liquids from all feedstreams. The
rule requires a separate limit for pumpable feedstreams because metals
present in pumpable feedstreams may partition between the combustion
gas and bottom ash (or kiln product) at a higher rate than metals in
nonpumpable feedstreams (i.e., low volatile metals in pumpable
feedstreams tend to partition primarily to the combustion gas). The
rule does not require a separate limit for semivolatile metals in
pumpable feedstreams because partitioning between the combustion gas
and bottom ash or product for these metals does not appear to be
affected by the physical state of the feedstream.238
---------------------------------------------------------------------------
\238\ See USEPA., ``Technical Support Document for HWC MACT
Standards, Volume IV: Compliance with the MACT Standards,'' February
1998.
---------------------------------------------------------------------------
To establish and comply with the feedrate limits, you must sample
and analyze and continuously monitor the flowrate of all feedstreams
(including hazardous waste, raw materials, and other fuels and
additives) except natural gas, process air, and feedstreams from vapor
recovery systems for semivolatile and low volatile metals content. As
proposed, you must establish maximum 12-hour rolling average feedrate
limits based on operations during the comprehensive performance test as
the average of the test run averages.
i. Use of Metal Surrogates. You may use one metal within a
volatility group as a surrogate during comprehensive performance
testing for other metals in that volatility group. For example, you may
use chromium as a surrogate during the performance test for all low
volatile metals. Similarly, you may use lead as a surrogate for
cadmium, the other semivolatile metal. This is because the metals
within a volatility group have generally the same volatility. Thus,
they will generally be equally difficult to control with an emissions
control device.
In addition, you may use either semivolatile metal as a surrogate
for any low volatile metal because semivolatile metals will be more
difficult to control than low volatile metals.239 This will
help alleviate concerns regarding the need to spike each metal during
comprehensive performance testing. If you want to spike metals, you
need not spike each metal to comply with today's rule but only one
metal within a volatility group (or potentially one semivolatile metal
for both volatility groups).
---------------------------------------------------------------------------
\239\ This is because a greater portion of semivolatile metals
volatilize in the combustion chamber and condenses in the flue gas
on small particulates or as fume. The major portion of low volatile
metals in flue gas are entrained on larger particulates (rather than
condensing from volatile species) and are thus easier to remove with
a particulate control device.
---------------------------------------------------------------------------
ii. Extrapolation of Performance Test Feedrate Levels to Calculate
Metal Feedrate Limits.240 You may request under
Sec. 63.1209(n)(2)(ii) to use the metal feedrates and emission rates
associated with the comprehensive performance test to extrapolate
feedrate limits and emission rates at levels higher than demonstrated
during the performance test. Extrapolation can be advantageous because
it avoids much of the spiking that sources normally undertake during
compliance testing and the associated costs, risks to operating and
testing personnel, and environmental loading from emissions.
---------------------------------------------------------------------------
\240\ Although this extrapolation discussion is presented in
context of semivolatile and low volatile metal feedrates, similar
provisions could be implemented for mercury feedrates.
---------------------------------------------------------------------------
Under an approved extrapolation approach, you would be required to
feed metals at no less than normal rates to narrow the amount of
extrapolation requested. Further, we expect that some spiking would be
desired to increase confidence in the measured, performance test
feedrate levels that will be used to project feedrate limits (i.e., the
errors associated with sampling and analyzing heterogeneous feedstreams
can be minimized by spiking known quantities). Extrapolation approaches
that request feedrate limits that are significantly higher than the
historical range of
[[Page 52947]]
feedrates should not be approved. Extrapolated feedrate limits should
be limited to levels within the range of the highest historical
feedrates for the source. We are taking this policy position to avoid
creating an incentive to burn wastes with higher than historical levels
of metals. Metals are not destroyed by combustion but rather are
emitted as a fraction of the amount fed to the combustor. If you want
to burn wastes with higher than historical levels of metals, you must
incur the costs and address the hazards to plant personnel and testing
crews associated with spiking metals into your feedstreams during
comprehensive performance testing.
Although we also investigated downward interpolation (i.e., between
the measured feedrate and emission level and zero), we are concerned
that downward interpolation may not be conservative. Our data indicates
that system removal efficiency can decrease as metal feedrate
decreases. Thus, actual emissions may be higher than emissions
projected by interpolation for lower feedrates. Consequently, we are
not allowing downward interpolation.
We are not specifying an extrapolation methodology to provide as
much flexibility as possible to consider extrapolation methodologies
that would best meet individual needs. We have investigated
extrapolation approaches 241 and discussed in the May 1997
NODA a statistical extrapolation methodology. Commenters raise
concerns, however, about defining a single acceptable extrapolation
method. They note that other methods might be developed in the future
that prove to be better, especially for a given source. We agree that
the approach discussed in the NODA may be too inflexible and are not
promulgating it today.242 Consequently, today's rule does
not specify a single method but allows you to recommend a method for
review and approval by permitting officials.
---------------------------------------------------------------------------
\241\ See USEPA, ``Draft Technical Support Document for HWC MACT
Standards (NODA), Volume III: Evaluation of Metal Emissions Database
to Investigate Extrapolation and Interpolation Issues,'' April 1997.
\242\ We plan to develop guidance on approaches that provide
greater flexibility.
---------------------------------------------------------------------------
Your recommended extrapolation methodology must be included in the
performance test plan. See Sec. 63.1207(f)(1)(x). Permitting officials
will review the methodology considering in particular whether: (1)
Performance test metal feedrates are appropriate (i.e., whether
feedrates are at least at normal levels, whether some level of spiking
would be appropriate depending on the heterogeneity of the waste, and
whether the physical form and species of spiked material is
appropriate); and (2) the requested, extrapolated feedrates are
warranted considering historical metal feedrate data.
We received comments both in favor of and in opposition to metals
extrapolation and interpolation. Those in favor suggest extrapolation
would simplify the comprehensive performance test procedure, reduce
costs, and decrease emissions during testing. Those in opposition are
concerned about: (1) Whether there is a predictable relationship
between feedrates and emission rates; (2) the possibility of higher
overall metals loading to the environment over the life of the facility
(i.e., because higher feedrate limits would be relatively easy to
obtain); (3) the difficulty in defining a ``normal'' feedrate for
facilities with variable metal feeds; and (4) whether all conditions
influencing potential metals emissions, such as combustion temperature
and metal compound speciation, could be adequately considered.
Given the pros and cons associated with various extrapolation
methodologies and policies, we are still concerned that sources would
be able to: (1) Feed metals at higher rates without a specific
compliance demonstration of the associated metals emissions; and (2)
obtain approval to feed metals at higher levels than normal, even
though all combustion sources should be trying to minimize metals
feedrates. However, because the alternative is metal spiking (as
evidenced in facility testing for BIF compliance) and metal spiking is
a significant concern as well, we find that the balance is better
struck by allowing, with site-specific review and where warranted
approval, extrapolation as a means to reduce unnecessary emissions,
reduce unnecessary costs incurred by facilities, and better protect the
health of testing personnel during performance tests.
iii. Conditional Waiver of Limit on Low Volatile Metals in Pumpable
Feedstreams. Commenters indicate that they may want to base feedrate
limits only on the worst-case feedstream--pumpable hazardous waste. The
feedrate limit would be based only on the feedrate of the pumpable
hazardous waste during the comprehensive performance test, even though
nonpumpable feedstreams would be contributing some metals to emissions.
In this situation, commenters suggest that separate feedrate limits for
total and pumpable feedstreams would not be needed. We agree that if
you define the total feedstream feedrate limit as the pumpable
feedstream feedrate during the performance test, dual limits are not
required. The feedrate of metals in total feedstreams must be monitored
and shown to be below the pumpable feedstream-based limit. See
Sec. 63.1209(n)(2)(C).
iv. Response to other Comments. We discuss below our response to
several other comments: (1) Recommendation for national uniform
feedrate limits; (2) concerns that feedstream monitoring is
problematic; and (3) recommendations that monitoring natural gas and
vapor recovery system feedstreams is unnecessary.
A commenter states that nationally uniform feedrate limits are
needed for metals and chlorine and that any other approach would be
inconsistent with the CAA. The commenter stated that hazardous waste
combustion device operators should not be allowed to self-select any
level of toxic metal feedrate just because they can show compliance
with the MACT standard. We believe that standards prescribing national
feedrate limits on metals or chlorine are not necessary to ensure MACT
control of metals and hydrochloric acid/chlorine gas and may be overly
restrictive. Emissions of metals and hydrochloric acid/chlorine gas are
controlled by controlling the feedrate of metals and chlorine, and
emission control devices. In developing MACT standards for a source
category, if we can identify emission levels that are being achieved by
the best performing sources using MACT control, we generally establish
the MACT standard as an emission level rather than prescribed operating
limits (e.g., feedrate limits). This approach is preferable because it
gives the source the option of determining the most cost-effective
measures to comply with the standard. Some sources may elect to comply
with the emission standards using primarily feedrate control, while
others may elect to rely primarily on emission controls. Under either
approach, the emission levels are equivalent to those being achieved by
the best performing existing sources. Other factors that we considered
in determining to express the standards as an emission level rather
than feedrate limits include: (1) There is not a single, universal
correlation factor between feedrate and metal emissions to use to
determine a national feedrate that would be equivalent to the emission
levels achieved by the best performing sources; (2) emission standards
communicate better to the public that meaningful controls are being
applied because the hazardous waste combustor
[[Page 52948]]
emission standards can be compared to standards for other waste
combustors (e.g., municipal and medical waste combustors) and
combustion devices; and (3) CEMS, the ultimate compliance assurance
tool that we encourage sources to use,243 are incompatible
with standards expressed as feedrate limits.
---------------------------------------------------------------------------
\243\ As discussed previously in the text, feedrate limits as a
compliance tool can be problematic for difficult to sample or
analyze feedstreams. Further, the emissions resulting from a given
feedrate level may increase (or decrease) over time, providing
uncertainty about actual emissions.
---------------------------------------------------------------------------
Another commenter is concerned that feedrate monitoring of highly
heterogeneous waste streams is problematic and analytical turnaround
times can be rather long. The commenter suggests that alternatives
beyond feedstream monitoring (such as predictive emissions monitoring)
should be allowed. Although we acknowledge that there may be
difficulties in monitoring the feedrate of metals or chlorine in
certain waste streams, there generally is no better way to assure
compliance with these standards other than using CEMS. Predictive
modeling appears to introduce unnecessarily some greater compliance
uncertainty than feedstream testing. Thus, we conclude that feedstream
monitoring is a necessary monitoring tool if a multimetals CEMS is not
used. (We also note that feedstream monitoring under MACT will not be
substantially more burdensome or problematic than the requirements now
in place under RCRA regulations.)
In addition, another commenter suggests that sources should not
have to monitor metals and chlorine in natural gas feedstreams because
it is impractical and levels are low and unvarying. The commenter
suggests that sources should be allowed to use characterization data
from natural gas vendors. We agree that the cost and possible hazards
of monitoring natural gas for metals and chlorine is not warranted
because our data shows metals are not present at levels of concern.
Therefore, you are not required to monitor metals and chlorine levels
in natural gas feedstreams. However, you must document in the
comprehensive performance test plan the expected levels of these
constituents and account for the expected levels in documenting
compliance with feedrate limits (e.g., by assuming worst-case
concentrations and monitoring the natural gas flowrate). See
Sec. 63.1209(c)(5).
Finally, some commenters are concerned that feedstreams from vapor
recovery systems (e.g., waste fuel tank and container emissions) are
difficult, costly, and often dangerous to monitor frequently for metals
and chlorine levels. Particularly because of some of the safety issues
concerned, the rule does not require continuous monitoring of metals
and chlorine for feedstreams from vapor recovery systems. However, as
is the case for natural gas, you must document in the comprehensive
performance test plan the expected levels of these constituents and
account for the expected levels in documenting compliance with feedrate
limits.
d. Maximum Chlorine Feedrate. As proposed, you must establish a
limit on the maximum feedrate for total chlorine (both organic and
inorganic) in all feedstreams based on the level fed during the
comprehensive performance test. A limit on maximum chlorine feedrate is
necessary because most metals are more volatile in the chlorinated
form. Thus, for example, more low volatile metals may report to the
combustion gas as a vapor than would be otherwise be entrained in the
combustion gas absent the presence of chlorine. In addition, the vapor
form of the metal is more difficult to control. Although most
semivolatile and low volatile metal species are in the particulate
phase at gas temperatures at the inlet to the particulate matter
control device, semivolatile metals that condense from the vapor phase
partition to smaller particulates and are more difficult to control
than low volatile metals that are emitted in the form of entrained,
larger particulates.
To establish and comply with the feedrate limit, you must sample
and analyze, and continuously monitor the flowrate, of all feedstreams
(including hazardous waste, raw materials, and other fuels and
additives) except natural gas, process air, and feedstreams from vapor
recovery systems for total chlorine content. As proposed, you must
establish a maximum 12-hour rolling average feedrate limit based on
operations during the comprehensive performance test as the average of
the test run averages.
Commenters suggest that chlorine feedrate limits are not needed for
sources with semivolatile and low volatile metal feedrates, when
expressed as maximum theoretical emission concentrations, less than the
emission standard. We agree. In this situation, you would be eligible
for the waiver of performance test under Sec. 63.1207(m). The
requirements of that provision (e.g., monitor and record metals
feedrates and gas flowrates to ensure that metals feedrate, expressed
as a maximum theoretical emission concentration, does not exceed the
emission standard) apply in lieu of the operating parameter limits
based on performance testing discussed above. We note, however, that
you would still need to establish a maximum feedrate limit for total
chlorine as an operating parameter limit for the hydrochloric acid/
chlorine gas emission standard (discussed below), unless you also
qualified for a waiver of that emission standard under Sec. 63.1207(m).
4. What Are the Monitoring Requirements for Carbon Monoxide and
Hydrocarbon?
You must maintain compliance with the carbon monoxide and
hydrocarbon emission standards using continuous emissions monitoring
systems (CEMS). In addition, you must use an oxygen CEMS to correct
continuously the carbon monoxide and hydrocarbon levels recorded by
their CEMS to 7 percent oxygen.
As proposed, the averaging period for carbon monoxide and
hydrocarbon CEMS is a one-hour rolling average updated each minute.
This is consistent with current RCRA requirements and commenters did
not recommend an alternative averaging period.
We also are promulgating performance specifications for carbon
monoxide, hydrocarbon, and oxygen CEMS. The carbon monoxide and oxygen
CEMS performance specifications are codified as Performance
Specification 4B in appendix B, part 60. This performance specification
is the same as the specification currently used for BIFs in appendix
IX, part 266. It also is very similar to existing appendix B, part 60
Performance Specifications 3 (for oxygen) and 4A (for carbon monoxide).
New specification 4B references many of the provisions of
Specifications 3 and 4A.
The hydrocarbon CEMS performance specification is codified as
Performance Specification 8A in appendix B, part 60. This specification
is also identical to the specification currently used for BIFs in
section 2.2 of appendix IX, part 266, with one exception. We deleted
the quality assurance section and placed it in the appendix to subpart
EEE of part 63 promulgated today to be consistent with our approach to
part 60 performance specifications.
We discuss below several issues pertaining to monitoring with these
CEMS: (1) The requirement to establish site-specific alternative span
values in some situations; (2) consequences of exceeding the span value
of the CEMS; and (3) the need to adjust the oxygen correction factor
during startup and shutdown.
a. When Are You Required to Establish Site-Specific Alternative
Span
[[Page 52949]]
Values? As proposed, if you normally operate at an oxygen correction
factor of more than 2 (e.g., a cement kiln monitoring carbon monoxide
in the by-pass duct), you must use a carbon monoxide or hydrocarbon
CEMS with a span proportionately lower than the values prescribed in
the performance specifications relative to the oxygen correction factor
at the CEMS sampling point. See the appendix to Subpart EEE, part 63:
Quality Assurance Procedures for Continuous Emissions Monitors Used for
Hazardous Waste Combustors.
This requirement arose from our experience with implementing the
BIF rule when we determined that the prescribed span values for the
carbon monoxide and hydrocarbon CEMS may lead to high error in
corrected emission values due to the effects of making the oxygen
correction. For example, a cement kiln may analyze for carbon monoxide
emissions in the by-pass duct with oxygen correction factors on the
order of 10. At the low range of the carbon monoxide CEMS span--200 ppm
as prescribed by Performance Specification 4B--with an acceptable
calibration drift of three percent, an error of 6 ppm is the result.
Accounting for the oxygen correction factor of 10, however, drives the
error in the measurement due to calibration drift up to 60 ppm. This is
more than half the carbon monoxide emission standard of 100 ppm and is
not acceptable. At carbon monoxide readings close to the 100 ppm
standard, true carbon monoxide levels may be well above or well below
the standard.
Consider the same example under today's requirement. For an oxygen
correction factor of 10, the low range span for the carbon monoxide
CEMS must be 200 divided by 10, or 20 ppm. The allowable calibration
drift of three percent of the span allows an error of 0.6 ppm at 20
ppm. Applying an oxygen correction factor of 10 results in an absolute
calibration drift error of 6ppm at an oxygen-corrected carbon monoxide
reading of 200.
b. What Are the Consequences of Exceeding the Span Value for Carbon
Monoxide and Hydrocarbon CEMS? If you do not elect to use a carbon
monoxide CEMS with a higher span value of 10,000 ppmv and a hydrocarbon
CEMS with a higher span value of 500 ppmv, you must configure your CEMS
so that a one-minute carbon monoxide value reported as 3,000 ppmv or
greater must be recorded (and used to calculate the hourly rolling
average) as 10,000 ppmv, and a one-minute hydrocarbon value reported as
200 ppmv or greater must be recorded as 500 ppmv.
If you elect to use a carbon monoxide CEMS with a span range of 0-
10,000 ppmv, you must use one or more carbon monoxide CEMS that meet
the Performance Specification 4B for three ranges: 0-200 ppmv; 1-3,000
ppmv; and 0-10,000 ppmv. Specification 4B provides requirements for the
first two ranges. For the (optional) high range of 0-10,000 ppmv, the
CEMS must also comply with Performance Specification 4B, except that
the calibration drift must be less than 300 ppmv and calibration error
must be less than 500 ppmv. These values are based on the allowable
drift and error, expressed as a percentage of span, that the
specification requires for the two lower span levels.
If you elect to use a hydrocarbon CEMS with a span range of 0-500
ppmv, you must use one or more hydrocarbon CEMS that meet Performance
Specification 8A for two ranges: 0-100 ppmv, and 0-500 ppmv.
Specification 8A provides requirements for the first range. For the
(optional) high range of 0-500 ppmv, the CEMS must also comply with
Performance Specification 8A, except: (1) The zero and high-level daily
calibration gas must be between 0 and 100 ppmv and between 250 and 450
ppmv, respectively; (2) the strip chart recorder, computer, or digital
recorder must be capable of recording all readings within the CEMS
measurement range and must have a resolution of 2.5 ppmv; (3) the CEMS
calibration must not differ by more than 15 ppmv after each
24 hour period of the seven day test at both zero and high levels; (4)
the calibration error must be no greater than 25 ppmv; and (5) the zero
level, mid-level, and high level values used to determine calibration
error must be in the range of 0-200 ppmv, 150-200 ppmv, and 350-400
ppmv, respectively. These requirements for the optional high range (0-
500 ppmv) are derived proportionately from the requirements in
Specification 8A for the lower range (0-100 ppmv).
The rule provides this requirement because we are concerned that,
when carbon monoxide and hydrocarbon monitors record a one-minute value
at the upper span level, the actual level of carbon monoxide or
hydrocarbons may be much higher (i.e., these CEMS often ``peg-out'' at
the upper span level). This has two inappropriate consequences. First,
the source may actually be exceeding the carbon monoxide or hydrocarbon
standard even though the CEMS indicates that it is not. Second, if the
carbon monoxide or hydrocarbon hourly rolling average were to exceed
the standard, triggering an automatic waste feed cutoff, the emission
level may drop back below the standard much sooner than it otherwise
would if the actual one-minute average emission levels were recorded
(i.e., rather than one-minute averages pegged at the upper span value).
Thus, this diminishes the economic disincentive for incurring automatic
waste feed cutoffs of not being able to restart the hazardous waste
feed until carbon monoxide and hydrocarbon levels are below the
standard.
We considered applying these ``out-of-span'' requirements when any
recorded value (i.e., any value recorded by the CEMS on a frequency of
at least every 15 seconds), rather than one-minute average values,
exceeded the upper span level. Commenters point out, however, that CEMS
may experience short-term electronic glitches that cause the monitored
output to spike for a very short time period. We concur, and conclude
that we should be concerned only about one-minute average values
because these short-term electronic glitches (that are not caused by
emission excursions) could result in an undesirable increase in
automatic waste feed cutoffs.
You may prefer to use carbon monoxide or hydrocarbon CEMS that have
upper span values between 3,000 and 10,000 ppmv and between 100 and 500
ppmv, respectively. If you believe that you would not have one-minute
average carbon monoxide or hydrocarbon levels as high as 10,000 ppmv
and 500 ppmv, respectively, you may determine that it would be less
expensive to use monitors with lower upper span levels (e.g., you may
be able to use a single carbon monoxide CEMS to meet performance
specifications for all three spans--the two lower spans required by
Specification 4B, and a higher span (but less than 10,000)). You must
still record, however, any one-minute average carbon monoxide or
hydrocarbon levels that are at or above the span as 10,000 ppmv and 500
ppmv, respectively.
c. How Is the Oxygen Correction Factor Adjusted during Startup and
Shutdown? You must identify in your Startup Shutdown, and Malfunction
Plan a projected oxygen correction factor to use during periods of
startup and shutdown. The projected oxygen correction factor should be
based on normal operations. See Sec. 63.1206(c)(2)(iii). The rule
provides this requirement because the oxygen concentration in the
combustor can exceed 15% during startup and shutdown, causing the
correction factor to increase exponentially from the normal value. Such
large correction factors result in corrected carbon
[[Page 52950]]
monoxide and hydrocarbon levels that are inappropriately inflated.
5. What Are the Operating Parameter Limits for Hydrochloric Acid/
Chlorine Gas?
You must maintain compliance with the hydrochloric acid/chlorine
gas emission standard by establishing and complying with limits on
operating parameters. See Sec. 63.1209(o). The following table
summarizes these operating parameter limits. All sources must comply
with the maximum chlorine feedrate limit. Other operating parameter
limits apply depending on the type of hydrochloric acid/chlorine gas
emission control device you use.
BILLING CODE 6560-50-P
[[Page 52951]]
[GRAPHIC] [TIFF OMITTED] TR30SE99.004
BILLING CODE 6560-50-C
[[Page 52952]]
Hydrochloric acid/chlorine gas emissions from hazardous waste
combustors are controlled by controlling the feedrate of total chlorine
(organic and inorganic) and either wet or dry scrubbers. We discuss
below the operating parameter limits that apply to each control
technique.
a. Maximum Chlorine Feedrate Limit. As proposed, you must establish
a limit on the maximum feedrate of chlorine, both organic and
inorganic, from all feedstreams based on levels fed during the
comprehensive performance test. Chlorine feedrate is an important
emission control technique because the amount of chlorine fed into a
combustor directly affects emissions of hydrochloric acid/chlorine gas.
To establish and comply with the feedrate limit, you must sample and
analyze, and continuously monitor the flowrate, of all feedstreams
(including hazardous waste, raw materials, and other fuels and
additives) except natural gas, process air, and feedstreams from vapor
recovery systems for chlorine content.244 Also as proposed,
you must establish a maximum 12-hour rolling average feedrate limit
based on operations during the comprehensive performance test as the
average of the test run averages.
---------------------------------------------------------------------------
\244\ See discussion in Section VII.D.3 above in the text for
the rationale for exempting these feedstreams for monitoring for
chlorine content.
---------------------------------------------------------------------------
One commenter states that a chlorine feedrate is not necessary for
cement kilns because cement kilns have an inherent incentive to control
chlorine feedrates: to avoid operational problems such as the formation
of material rings in the kiln or alkali-chloride condensation on the
walls. Although we understand that cement kilns must monitor chlorine
feedrates for operational reasons, several cement kilns in our data
base emit levels of hydrochloric acid/chlorine gas at levels above
today's emissions standard. We conclude, therefore, that the
operational incentive to limit chlorine feedrates is not adequate to
ensure compliance with the hydrochloric acid/chlorine gas emission
standard.
b. Wet Scrubbers. If your combustor is equipped with a wet
scrubber, you must establish, continuously monitor, and comply with
limits on the following operating parameters:
i. Maximum Flue Gas Flowrate or Kiln Production Rate. As proposed,
you must establish a limit on maximum flue gas flowrate or kiln
production rate as a surrogate. See 61 FR at 17433. Gas flowrate is a
key parameter affecting the control efficiency of a wet scrubber (and
any emissions control device). As gas flowrate increases, control
efficiency generally decreases unless other operating parameters are
adjusted to accommodate the increased flowrate. Cement kilns and
lightweight aggregate kilns may establish a limit on maximum production
rate (e.g., raw material feedrate or clinker or aggregate production
rate) in lieu of a maximum gas flowrate given that production rate
directly relates to flue gas flowrate.
As proposed, you must establish a maximum gas flowrate or
production rate limit as the average of the maximum hourly rolling
averages for each run of the comprehensive performance test.
We did not receive adverse comment on this compliance parameter.
ii. Minimum Pressure Drop Across the Scrubber. You must establish a
limit on minimum pressure drop across the scrubber. If your combustor
is equipped with a high energy scrubber (e.g., venturi, calvert), you
must establish an hourly rolling average limits based on operations
during the comprehensive performance test. The hourly rolling average
is established as the average of the test run averages.
If your combustor is equipped with a low energy scrubber (e.g.,
spray tower), you must establish a limit on minimum pressure drop based
on the manufacturer's specification. You must comply with the limit on
an hourly rolling average basis.
Pressure drop across a wet scrubber is an important operating
parameter because it is an indicator of good mixing of the two fluids,
the scrubber liquid and the flue gas. A low pressure drop indicates
poor mixing and, hence, poor efficiency. A high pressure drop indicates
good removal efficiency.
One commenter states that wet scrubber pressure drop is not an
important parameter for packed-bed, low energy wet scrubbers. The
commenter states that the performance of a packed-bed scrubber is based
on good liquid-to-gas contacting. Thus, performance is dependent on
packing design and scrubber fluid flow. In addition, the commenter
states that scrubber liquid flow rate (and recirculation rate and make-
up water flow rate) are adequate for assuring proper scrubber
operation. We note that for many types of low energy wet scrubbers,
pressure drop can be a rough indicator of scrubber liquid and flue gas
contacting. Thus, although it is not a critical parameter, the minimum
pressure drop of a low energy scrubber should still be monitored and
complied with on a continuous basis.
Because pressure drop for a low energy scrubber (e.g., spray
towers, packed beds, or tray towers) is not as important as for a high
energy scrubber to maintain performance, however, the rule requires you
to establish a limit on the minimum pressure drop for a low energy
scrubber based on manufacturer specifications, rather than levels
demonstrated during compliance testing. You must comply with this limit
on an hourly rolling average basis. The pressure drop for high energy
wet scrubbers, such as venturi or calvert scrubbers, however, is a key
operating parameter to ensure the scrubber maintains performance.
Accordingly, you must base the minimum pressure drop for these devices
on levels achieved during the comprehensive test, and you must
establish an hourly rolling average limit.
iii. Minimum Liquid Feed Pressure. You must establish a limit on
minimum liquid feed pressure to a low energy scrubber. The limit must
be based on manufacturer's specifications and you must comply with it
on an hourly rolling average basis.
The rule requires a limit on liquid feed pressure because the
removal efficiency of a low energy wet scrubber can be directly
affected by the atomization efficiency of the scrubber. A drop in
liquid feed pressure may be an indicator of poor atomization and poor
scrubber removal efficiency. We are not requiring a limit on minimum
liquid feed pressure for high energy scrubbers because liquid flow rate
rather than feed pressure is the dominant operating parameter for high
energy scrubbers.
We acknowledge, however, that not all wet scrubbers rely on
atomization efficiency to maintain performance. If manufacturer's
specifications indicate that atomization efficiency is not an important
parameter that controls the efficiency of your scrubber, you may
petition permitting officials under Sec. 63.1209(g)(1) to waive this
operating parameter limit.
iv. Minimum Liquid pH. You must establish dual ten-minute and
hourly rolling average limits on minimum pH of the scrubber water based
on operations during the comprehensive performance test. The hourly
rolling average is established as the average of the test run averages.
The pH of the scrubber liquid is an important operating parameter
because, at low pH, the scrubber solution is more acidic and removal
efficiency of hydrochloric acid and chlorine gas decreases.
These requirements, except for the proposed ten-minute averaging
period, are the same as we proposed. See 61 FR at 17433. We did not
receive adverse comments.
[[Page 52953]]
v. Minimum Scrubber Liquid Flowrate or Minimum Liquid/Gas Ratio.
You must establish an hourly rolling average limits on either minimum
scrubber liquid flowrate and maximum flue gas flowrate or minimum
liquid/gas ratio based on operations during the comprehensive
performance test. The hourly rolling average is established as the
average of the test run averages.
Liquid flowrate and flue gas flowrate or liquid/gas ratio are
important operating parameters because a high liquid-to-gas-flowrate
ratio is indicative of good removal efficiency.
We had proposed to limit the liquid-to-gas ratio only. Commenters
suggest that a limit on liquid-to-gas flow ratio would not be needed if
the liquid flowrate and flue gas flowrate were limited instead. They
reason that, because gas flowrate is already limited, limiting liquid
flowrate as well would ensure that the liquid-to-gas ratio is
maintained. We agree. During normal operations, the liquid flowrate can
only be higher than levels during the performance test, and gas
flowrate can only be lower than during the performance test. Thus, the
numerator in the liquid flowrate/gas flowrate ratio could only be
larger, and the denominator could only be smaller. Consequently, the
liquid flowrate/gas flowrate during normal operations will always be
higher than during the comprehensive performance test. Consequently, we
agree that a limit on liquid-to-gas-ratio is not needed if you
establish a limit on liquid flowrate and flue gas flowrate.
Establishing limits on these parameters is adequate to ensure that the
liquid flowrate/gas ratio is maintained.245
---------------------------------------------------------------------------
\245\ In fact, complying with limits on liquid flowrate and gas
flowrate, rather than complying with a liquid flowrate/gas flowrate
ratio, is a more conservative approach to ensure that the
performance test ratio is maintained (at a minimum). Thus, we prefer
that you establish a limit on liquid flowrate (in conjunction with
the limit gas flowrate) in lieu of a limit on the ratio.
---------------------------------------------------------------------------
c. Dry Scrubbers. A dry scrubber removes hydrochloric acid from the
flue gas by adsorbing the hydrochloric acid onto sorbent, normally an
alkaline substance like limestone. As proposed, if your combustor is
equipped with a dry scrubber, you must establish, continuously monitor,
and comply with limits on the following operating parameters: Gas
flowrate or kiln production rate; sorbent feedrate; carrier fluid
flowrate or nozzle pressure drop; and sorbent specifications. See 61 FR
at 17434.
i. Maximum Flue Gas Flowrate or Kiln Production Rate. As proposed,
you must establish a limit on maximum flue gas flowrate or kiln
production rate as a surrogate. The limit is established and monitored
as discussed above for wet scrubbers.
ii. Minimum Sorbent Feedrate. You must establish an hourly rolling
average limit on minimum sorbent feedrate based on feedrate levels
during the comprehensive performance test. The hourly rolling average
is established as the average of the test run averages.
Sorbent feedrate is important because, as more sorbent is fed into
the dry scrubber, removal efficiency of hydrochloric acid and chlorine
gas increases.246 Conversely, lower sorbent feedrates tend
to cause removal efficiency to decrease.
---------------------------------------------------------------------------
\246\ We note that sorbent should be fed to a dry scrubber in
excess of the stoichiometric requirements for neutralizing the anion
component in the flue gas. Lower levels of sorbent, even above
stoichiometric requirements, would limit the removal of acid gasses.
---------------------------------------------------------------------------
At proposal, we invited comment on whether a ten-minute rolling
average is appropriate for sorbent feedrate (61 FR at 17434). We were
concerned that some facilities may not automate their dry scrubbers to
add sorbent solutions but instead add batches of virgin sorbent
solution. Thus, we were concerned that a ten-minute rolling average may
not be practicable in all cases. Some commenters are concerned that a
ten-minute limit would be difficult to measure, especially in the case
of batch addition of sorbent. Nonetheless, we have determined upon
reanalysis that sorbent is not injected into the flue gas in
``batches.'' Although sorbent may be added in batches to storage or
mixing vessels, it must be injected into the flue gas continuously to
provide continuous and effective removal of acid gases. Thus, ten-
minute rolling average limits would be practicable and appropriate for
sorbent injection feedrates if ten-minute averages were required in
this final rule.247 However, as discussed in Part Five,
Section VII.B, we have decided to not require ten-minute averaging
periods on a national basis. Permitting officials may, however,
determine that shorter averaging periods are needed to better assure
compliance with the emission standard.
---------------------------------------------------------------------------
\247\ We note that flowrate measurement devices are available
for ten-minute average times (e.g., those based on volumetric screw
feeders which provide instantaneous measurements).
---------------------------------------------------------------------------
iii. Minimum Carrier Fluid Flowrate or Nozzle Pressure Drop. A
carrier fluid, normally air or water, is necessary to transport and
inject the sorbent into the gas stream. As proposed, you must establish
and continuously monitor a limit on either minimum carrier gas or water
flowrate or pressure drop across the nozzle to ensure that the flow and
dispersion of the injected sorbent into the flue gas stream is
maintained. You must base the limit on manufacturer's specifications,
and comply with the limit on a one-hour rolling average basis.
Without proper carrier flow to the dry scrubber, the sorbent flow
into the scrubber will decrease causing the efficiency to decrease.
Nozzle pressure drop is also an indicator of carrier gas flow into the
scrubber. At higher pressure drops, more sorbent is carried to the dry
scrubber.
iv. Identification of Sorbent Brand and Type or Adsorption
Properties. You must either identify the sorbent brand and type used
during the comprehensive performance test and continue using that
sorbent, or identify the adsorption properties of that sorbent and use
a sorbent having equivalent or better properties. This will ensure that
the sorbent's adsorption properties are maintained.
We proposed to require sources to continue to use the same sorbent
brand and type as they used during the comprehensive performance test
or obtain a waiver from this requirement from the Administrator. See 61
FR at 17434. As discussed above in the context of specifying the brand
of carbon used in carbon injection systems to control dioxin/furan, we
have determined that sources should have the option of using
manufacturer's specifications to specify the sorption properties of the
sorbent used during the comprehensive performance test. You may use
sorbent of other brands or types provided that it has equivalent or
better sorption properties. You must include in the operating record
written documentation that the substitute sorbent will provide the same
level of control as the original sorbent.
6. What Are the Operating Parameter Limits for Particulate Matter?
You must maintain compliance with the particulate matter emission
standard by establishing and complying with limits on operating
parameters. See Sec. 63.1209(m). The following table summarizes these
operating parameter limits. All incinerators must comply with the limit
on maximum ash feedrate. Other operating parameter limits apply
depending on the type of particulate matter control device you use.
BILLING CODE 6560-50-P
[[Page 52954]]
[GRAPHIC] [TIFF OMITTED] TR30SE99.005
BILLING CODE 6560-50-C
[[Page 52955]]
Particulate matter emissions from hazardous waste combustors are
controlled by controlling the feedrate of ash to incinerators and using
a particulate matter control device. We discuss below the operating
parameter limits that apply to each control technique.
a. Maximum Ash Feedrate. As proposed, if you own or operate an
incinerator, you must establish a limit on the maximum feedrate of ash
from all feedstreams based on the levels fed during the comprehensive
performance test. To establish and comply with the feedrate limit, you
must sample and analyze, and continuously monitor the flowrate of all
feedstreams (including hazardous waste, and other fuels and additives)
except natural gas, process air, and feedstreams from vapor recovery
systems for ash content.248 Also as proposed, you must
establish a maximum 12-hour rolling average feedrate limit based on
operations during the comprehensive performance test as the average of
the test run averages. See 61 FR at 17438.
---------------------------------------------------------------------------
\248\ See discussion in Section VII.D.3 above in the text for
the rationale for exempting these feedstreams from monitoring for
ash content.
---------------------------------------------------------------------------
Ash feedrate for incinerators is an important particulate matter
control parameter because ash feedrates can relate directly to
emissions of particulate matter (i.e., ash contributes to particulate
matter in flue gas). We are not requiring an ash feedrate limit for
cement or lightweight aggregate kilns because particulate matter from
those combustors is dominated by raw materials entrained in the flue
gas. The contribution to particulate matter of ash from hazardous waste
or other feedstreams is not significant. We discussed this issue at
proposal.
A commenter states that ash feedrate limits are not needed for
combustors using fabric filters, suggesting that fabric filter pressure
drop and opacity monitoring are sufficient for compliance assurance. We
discuss previously in this section (i.e., Part Five, Section VII) our
concern that neither opacity monitors, nor limits on control device
operating parameter, nor limits on the feedrates of constituents that
can contribute directly to emissions of hazardous air pollutants
comprise an ideal compliance assurance regime. We would prefer the use
of a particulate matter CEMS for compliance assurance but cannot
achieve that goal at this time. Absent the use of a CEMS and given the
limitations of the individual compliance tools currently available, we
are reluctant to forgo on a national, generic basis requiring limits on
an operating parameter such as ash feedrate that we know can relate
directly to particulate emissions. However, you may petition permitting
officials under Sec. 63.1209(g)(1) for approval to waive the ash
feedrate limit based on data or information documenting that pressure
drop across the fabric filter coupled with an opacity monitor would
provide equivalent or better compliance assurance than a limit on ash
feedrate.
b. Wet Scrubbers. As proposed, if your combustor is equipped with a
wet scrubber, you must establish, continuously monitor, and comply with
limits on the operating parameters discussed below. High energy wet
scrubbers (e.g., venturi, calvert) remove particulate matter by
capturing particles in liquid droplets and separating the droplets from
the gas stream. Ionizing wet scrubbers use both an electrical charge
and wet scrubbing to remove particulate matter. Low energy wet
scrubbers that are not ionizing wet scrubbers (e.g., packed bed, spray
tower) are only subject to the scrubber water solids content operating
parameter requirements for particulate matter control because they are
primarily used to control emissions of acid gases and only provide
incidental particulate matter control.
i. Maximum Flue Gas Flowrate or Kiln Production Rate. For high
energy and ionic wet scrubbers, you must establish a limit on maximum
flue gas flowrate or kiln production rate as a surrogate. See 61 FR at
17438. Gas flowrate is a key parameter affecting the control efficiency
of a wet scrubber (and any emissions control device). As gas flowrate
increases, control efficiency generally decreases unless other
operating parameters are adjusted to accommodate the increased
flowrate. Cement kilns and lightweight aggregate kilns may establish a
limit on maximum production rate (e.g., raw material feedrate or
clinker or aggregate production rate) in lieu of a maximum gas flowrate
given that production rate directly relates to flue gas flowrate.
As proposed, you must establish a maximum gas flowrate or
production rate limit as the average of the maximum hourly rolling
averages for each run of the comprehensive performance test.
ii. Minimum Pressure Drop Across the Scrubber. For high energy
scrubbers only, you must establish an hourly rolling average limits on
minimum pressure drop across the scrubber based on operations during
the comprehensive performance test. The hourly rolling average is
established as the average of the test run averages. See the discussion
in Section VII.D.5.b above for a discussion on the approach for
calculating limits from comprehensive performance test data.
iii. Minimum Scrubber Liquid Flowrate or Minimum Liquid/Gas Ratio.
For high energy wet scrubbers, you must establish an hourly rolling
average limits on either minimum scrubber liquid flowrate and maximum
flue gas flowrate or minimum liquid/gas ratio based on operations
during the comprehensive performance test. The hourly rolling average
is established as the average of the test run averages. See the
discussion in Section VII.D.5.b above for a discussion on the approach
for calculating limits from comprehensive performance test data.
iv. Maximum Solids Content of Scrubber Water or Minimum Blowdown
Rate Plus Minimum Scrubber Tank Volume or Level. For all wet scrubbers,
to maintain the solids content of the scrubber water to levels no
higher than during the comprehensive performance test, you must
establish a limit on either: (1) Maximum solids content of the scrubber
water; or (2) minimum blowdown rate plus minimum scrubber tank volume
or level. If you elect to establish a limit on maximum solids content
of the scrubber water, you must comply with the limit either by: (1)
Continuously monitoring the solids content and establishing 12-hour
rolling average limits based on solids content during the comprehensive
performance test; or (2) periodic manual sampling and analysis of
scrubber water for solids content. Under option 1, the 12-hour rolling
average is established as the average of the test run averages. Under
option 2, you must either comply with a default sampling and analysis
frequency for scrubber water solids content of once per hour or
recommend an alternative frequency in your comprehensive performance
test plan that you submit for review and approval.
Solids content in the scrubber water is an important operating
parameter because as the solids content increases, particulate
emissions increase. This is attributable to evaporation of scrubber
water and release of previously captured particulate back into the flue
gas. Blowdown is the amount of scrubber liquid removed from the process
and not recycled back into the wet scrubber. As scrubber liquid is
removed and not recycled, solids are removed. Thus, blowdown is an
operating parameter that affects solids content and can be used as a
surrogate for measuring solids content directly. See 61 FR 17438.
The proposed rule would have required continuously monitored limits
on either minimum blowdown or a
[[Page 52956]]
maximum solids content. In response to comments and upon reanalysis of
the issues, we conclude that we need to make two revisions to these
requirements. First, we are concerned that it may be problematic to
continuously monitor the solids content of scrubber water.
Consequently, we revised the requirements to allow manual sampling and
analysis on an hourly basis, unless you justify an alternative
frequency. Second, we are concerned that a limit on blowdown rate
without an associated limit on either minimum scrubber water tank
volume or level would not be adequate to provide control of solids
content. The solids concentration in blowdown tanks could be higher at
lower water levels. Therefore, water levels need to be at least
equivalent to the levels during the comprehensive performance test.
This should not be a significant additional burden. Sources should be
monitoring the water level in the scrubber water tank as a measure of
good operating practices. Consequently, we revise the requirement to
require a minimum tank volume or level in conjunction with a minimum
blowdown rate for sources that elect to use that compliance option.
c. Fabric Filter. If your combustor is equipped with a fabric
filter, you must establish, continuously monitor, and comply with
limits on the operating parameters discussed below.
i. Maximum Flue Gas Flowrate or Kiln Production Rate. As proposed,
you must establish a limit on maximum flue gas flowrate or kiln
production rate as a surrogate. Gas flowrate is a key parameter
affecting the control efficiency of a fabric filter (and any emissions
control device). As gas flowrate increases, control efficiency
generally decreases unless other operating parameters are adjusted to
accommodate the increased flowrate. Cement kilns and lightweight
aggregate kilns may establish a limit on maximum production rate (e.g.,
raw material feedrate or clinker or aggregate production rate) in lieu
of a maximum gas flowrate given that production rate directly relates
to flue gas flowrate.
As proposed, you must establish a maximum gas flowrate or
production rate limit as the average of the maximum hourly rolling
averages for each run of the comprehensive performance test.
ii. Minimum Pressure Drop and Maximum Pressure Drop Across the
Fabric Filter. You must establish a limit on minimum pressure drop and
maximum pressure drop across each cell of the fabric filter based on
manufacturer's specifications.
Filter failure is typically due to filter holes, bleed-through
migration of particulate through the filter and cake, and small ``pin
holes'' in the filter and cake. Because low pressure drop is an
indicator of one of these types of failure, pressure drop across the
fabric filter is an indicator of fabric filter failure.
We had proposed to establish limits on minimum pressure drop based
on the performance test. Commenters indicate, however, that maintaining
a pressure drop not less than levels during the performance test will
not ensure baghouse performance. We concur. The pressure change caused
by fabric holes may not be measurable, especially at large sources with
multiple chamber filter housing units that operate in parallel. In
addition, operating at high pressure drop may not be desirable because
high pressures can create pin holes.
Nonetheless, establishing a limit on minimum pressure drop based on
manufacturer's recommendations, as suggested by a commenter, is a
reasonable and prudent approach to help ensure fabric filter
performance. We have since determined that an operating parameter limit
for maximum pressure drop across each cell of the fabric filter, based
on manufacturer specifications, is also necessary. As discussed above,
a high pressure drop in a cell of a fabric filter may cause small
pinholes to form or may be indicative of bag blinding or plugging,
which could result in increased particulate emissions. We do not
consider this additional provision to be burdensome, especially because
both the maximum and minimum pressure drop limits are based on
manufacturer specifications on an hourly rolling average. These
pressure drop monitoring requirements, in combination with COMS for
cement kilns and bag leak detection systems for incinerators and
lightweight aggregate kilns, provide a significant measure of assurance
that control performance is maintained.
d. Electrostatic Precipitators and Ionizing Wet Scrubbers. As
proposed, if your combustor is equipped with an electrostatic
precipitator or ionizing wet scrubber, you must establish, continuously
monitor, and comply with limits on the operating parameters discussed
below.
i. Maximum Flue Gas Flowrate or Kiln Production Rate. You must
establish a limit on maximum flue gas flowrate or kiln production rate
as a surrogate. Gas flowrate is a key parameter affecting the control
efficiency of an emissions control device. As gas flowrate increases,
control efficiency generally decreases unless other operating
parameters are adjusted to accommodate the increased flowrate. Cement
kilns and lightweight aggregate kilns may establish a limit on maximum
production rate (e.g., raw material feedrate or clinker or aggregate
production rate) in lieu of a maximum gas flowrate given that
production rate directly relates to flue gas flowrate.
As proposed, you must establish a maximum gas flowrate or
production rate limit as the average of the maximum hourly rolling
averages for each run of the comprehensive performance test.
ii. Minimum Secondary Power Input to Each Field. You must establish
an hourly rolling average limit on minimum secondary power (kVA) input
to each field of the electrostatic precipitator or ionizing wet
scrubber based on operations during the comprehensive performance test.
The hourly rolling average is established as the average of the test
run averages.
Electrostatic precipitators capture particulate matter by charging
the particulate in an electric field and collecting the charged
particulate on an inversely charged collection plate. Higher voltages
improve magnetic field strength, resulting in charged particle
migration to the collection plate. High current leads to an increased
particle charging rate and increased electric field strength near the
collection electrode, increasing collection at the plate, as well.
Therefore, maximizing both voltage and current by specifying minimum
power input to the electrostatic precipitator is desirable for good
particulate matter collection in electrostatic precipitators. For these
reasons, the rule requires you to monitor power input to each field of
the electrostatic precipitator to ensure that collection efficiency is
maintained at performance test levels.
Power input to an ionizing wet scrubber is important because it
directly affects particulate removal. Ionizing wet scrubbers charge the
particulate prior to it entering a packed bed wet scrubber. The
charging aids in the collection of the particulate onto the packing
surface in the bed. The particulate is then washed off the packing by
the scrubber liquid. Therefore, power input is a key parameter to
proper operation of an ionizing wet scrubber.
One commenter suggests that a minimum limit on electrostatic
precipitator voltage be used instead of power input because, at low
particulate matter loadings, operation at maximum power input is
inefficient. Another commenter suggests that neither a limit on voltage
or power input is appropriate because a minimum limit would
[[Page 52957]]
actually cause a potential decrease in operational efficiency (required
power input and voltage are strong functions of gas and particulate
characteristics, electrostatic precipitator arcing and sparking at high
voltage and power requirements, etc.). Alternatively, they recommend
that a limit on the minimum number of energized electrostatic
precipitator fields be established. We continue to maintain that a
minimum limit on power input to each field of the electrostatic
precipitator is generally accepted as an appropriate parameter for
assuring electrostatic precipitator performance. Consequently, it is an
appropriate parameter for a generic, national standard. If you believe,
however, that in your situation limits on alternative operating
parameters may better assure that control performance is maintained you
may request approval to use alternative monitoring approaches under
Sec. 63.1209(1).
Another commenter suggests that, in addition to a minimum power
input for an ionizing wet scrubber, a limit should be set on the
maximum time allowable to be below the minimum voltage. While feasible,
we conclude that this limit is not necessary on a national basis
because the one hour rolling average requirement limits the amount of
time a source can operate below its minimum voltage limit. We
acknowledge, however, that a permit writer may find it necessary to
require shorter averaging periods (e.g., ten-minute or instantaneous
limits) to better control the amount of time a source can operate at
levels below its limit.
7. What Are the Operating Parameter Limits for Destruction and Removal
Efficiency?
You must establish, monitor, and comply with the same operating
parameter limits to ensure compliance with the destruction and removal
efficiency (DRE) standard as you establish to ensure good combustion
practices are maintained for compliance with the dioxin/furan emission
standard. See Sec. 63.1209(j) and the discussion in Section VII.D.1
above. This is because compliance with the DRE standard is ensured by
maintaining combustion efficiency using good combustion practices.
Thus, the DRE operating parameters are: maximum waste feedrate for
pumpable and nonpumpable wastes, minimum gas temperature for each
combustion chamber, maximum gas flowrate or kiln production rate, and
parameters that you recommend to ensure the operations of each
hazardous waste firing system are maintained.249
---------------------------------------------------------------------------
\249\ You are required to establish operating requirements only
for hazardous waste firing systems because of DRE standard applies
only to hazardous waste. Permitting officials may determine on a
site-specific basis under authority of Sec. 63.1209(g)(2), however,
that combustion of other fuels or wastes may affect your ability to
maintain DRE for hazardous waste. Accordingly, permitting officials
may define operating requirements for other (i.e., other than
hazardous waste) waste or fuel firing systems. Permitting officials
may also determine under that provision on a site-specific basis
that operating requirements other than those prescribed for DRE (and
good combustion practices) may be needed to ensure compliance with
the DRE standard.
---------------------------------------------------------------------------
VIII. Which Methods Should Be Used for Manual Stack Tests and
Feedstream Sampling and Analysis?
This part discusses the manual stack test and the feedstream
sampling and analysis methods required by today's rule.
A. Manual Stack Sampling Test Methods
To demonstrate compliance with today's rule, you must use: (1)
Method 0023A for dioxin and furans; (2) Method 29 for mercury,
semivolatile metals, and low volatile metals; (3) Method 26A for
hydrochloric acid and chlorine; and (4) Method 5 or 5i for particulate
matter. These methods are found at 40 CFR part 60, appendix A, and in
``Test Methods for Evaluating Solid Waste, Physical/Chemical Methods,''
EPA publication.
In the NPRM, we proposed that BIF manual stack test methods
currently located in SW-846 be required to demonstrate compliance with
the proposed standards. Based on public comments from the proposal, in
the December 1997 NODA we considered simply citing the ``Air Methods''
found in appendix A to part 60. Our rationale was that facilities may
be required to perform two identical tests, one from SW-846 for
compliance with MACT or RCRA and one from part 60, appendix A, for
compliance with other air rules using identical test methods simply
because one method is an SW-846 method and the other an Air Method. See
62 FR at 67803. To facilitate compliance with all air emissions stack
tests, we stated that we would list the methods found in 40 CFR part
60, appendix A, as the stack test methods used to comply with the
standards. Later in this section we present an exception for dioxin and
furan testing.
In today's rule, we adopt the approach of the December 1997 NODA
and require that the test methods found in 40 CFR part 60, appendix A
be used to demonstrate compliance with the emission standards of
today's rule, except for dioxin and furan. Specifically, today's rule
requires you to use Method 0023A in SW-846 for sampling dioxins and
furans from stack emissions. As noted by commenters, improvements have
been made to the dioxin and furan Method 0023A in the Third Update of
SW-846 that have been previously incorporated into today's regulations.
See the 40 CFR 63.1208(a), incorporation of SW-846 by reference.
However, these have not yet been incorporated into 40 CFR part 60,
Appendix A. To capture these improvements to the method, today's rule
incorporates by reference SW-846 Method 0023A. We have evaluated both
methods. Use of the improved Method 0023A will not affect the
achievability of the dioxin and furan standard.
In the proposal, we sought comment on the handling of nondetect
values for congeners analyzed using the dioxin and furan method. We
also sought comment on whether the final rule should specify minimum
sampling times. We proposed allowing facilities to assume that
emissions of dioxins and furans congeners are zero if the analysis
showed a nondetect for that congener and the sample time for the test
method run was at least 3 hours. See 61 FR 17378. Dioxin/furan results
may not be blank corrected. We received several comments this proposed
approach, which are summarized below.
One commenter believes that a minimum dioxin/furan sampling time of
two hours is sufficient. Another commenter believes that a minimum
sample time as well as a minimum sample volume should be specified.
Several commenters agree that nondetects should be treated as zero
(which is consistent with the German standard) and prefer the three
hour minimum sample period because this would help eliminate intra-
laboratory differences and difficulties with matrix effects in
attaining low detection limits. One commenter believes that EPA should
specify the required detection limit for each congener analysis,
otherwise the provision to assign zeroes to nondetected congeners in
the TEQ calculation is open to abuse and could result in an
understatement of the true dioxin/furan emissions. This commenter also
believes that a source should not be allowed to sample dioxin/furans
for time periods less than three hours, even if they assume nondetects
are present at the detection limit.
Upon carefully considering all the above comments, we conclude that
the following approach best addresses the nondetect issue. The final
rule requires all sources to sample dioxin/furans for a minimum of
three hours for each run,
[[Page 52958]]
and requires all sources to collect a flue gas sample of at least 2.5
dscm. We conclude both these requirements are necessary to maintain
consistency from source to source, and to better assure that the
dioxin/furan emission results are accurate and representative. We
conclude that these two requirements are achievable and appropriate
250. These requirements are consistent with the requirements
included in the proposed Portland Cement Kiln MACT rule (see 64 FR at
31898). The final rule also allows a source to assume all nondetected
congeners are not present in the emissions when calculating TEQ values
for compliance purposes.
---------------------------------------------------------------------------
\250\ See Final Technical Support Document, Volume IV, Chapter
3, for further discussion.
---------------------------------------------------------------------------
We considered whether it would be appropriate to specify required
minimum detection limits for each congener analysis in order to better
assure that sources achieved reasonable detection limits, as one
commenter recommended. Such a requirement would prevent abuse and
understatements of the true dioxin/furan emissions. We conclude,
however, that it is not appropriate to finalize minimum detection
limits in this rulemaking without giving the opportunity to all
interested parties to review and comment on such an approach.
However, we are concerned that (1) sources have no incentive to
achieve low detection limits; and (2) sources may abuse the provision
that allows nondetected congener results to be treated as if they were
not present. As explained in the Final Technical Support Document
referenced in the preceding paragraph, if one assumes that all dioxin/
furan congeners are present at what we consider to be poor detection
limits using Method 23A, the resultant TEQ can approach the emission
standard. This outcome is clearly inappropriate from a compliance
perspective.
As a result, we highly recommend that this issue be addressed in
the review process of the performance test workplan. Facilities should
submit information that describes the target detection limits for all
congeners, and calculate a dioxin/furan TEQ concentration assuming all
congeners are present at the detection limit (similar to what is done
for risk assessments). If this value is close to the emission standard,
both the source and the regulatory official should determine if it is
appropriate to either sample for longer time periods or investigate
whether it is possible to achieve lower detection limits by using
different analytical procedures that are approved by the Agency.
Also, EPA has developed analytical standards for certain mono-
through tri-chloro dioxin and furan congeners. We encourage you to test
for these congeners in addition to the congeners that comprise today's
standards. This can be done at very little increased cost. If you test
for these additional congeners, please include the results in your
Notification of Compliance. We would like this data so we can develop a
database from which to determine which (if any) of these compounds can
act as surrogate(s) for the dioxin and furan congeners which comprise
the total and TEQ. If easily measurable surrogate(s) can be found, we
can then start the development of a CEMS for these surrogates. A
complete list of these congeners will be included in the implementation
document for this rule and updated periodically through guidance.
One commenter suggests that a source be allowed to conduct one
extended dioxin/furan sampling event as opposed to three separate runs
with three separate sampling trains because this would minimize the
radioactive waste generated for sources that combust mixed waste. We
conclude this issue should be handled on a site-specific basis,
although an allowance of such an approach seems reasonable. A source
can petition the Agency under the provisions of Sec. 63.7(f) for an
alternative test method for such a site-specific determination.
The final rule also adopts the approach discussed in the December
1997 NODA for sampling of mercury, semi-volatile metals, and low-
volatile metals. Therefore, for stack sampling of mercury, semi-
volatile metals, and low-volatile metals, you are required to use
Method 29 in 40 CFR part 60, appendix A. No adverse comments were
received concerning this approach in the December 1997 NODA.
For compliance with the hydrochloric acid and chlorine standards,
today's rule requires that you use Method 26A in 40 CFR part 60,
appendix A. Commenters state that we should instead require a method
involving the Fourier Transform Infrared and Gas Filter Correlation
Infrared instrumental techniques. Commenters contend that Method 26A is
biased high at cement kilns because it collects ammonium chloride in
addition to the hydrochloric acid and chlorine gas emissions it was
designed to report. Commenters also indicate that the Fourier Transform
Infrared and Gas Filter Correlation Infrared were validated against
Method 26A and that these alternative methods do not bias the results
high due to ammonium chloride 251. The data for today's
hydrochloric acid standard was derived using the SW-846 equivalent to
Method 26A (Method 0050) as the reference method. Therefore, today's
standard accounts for the ammonium chloride collection bias. We reject
the idea that we should require other methods. If the commenters are
correct, other methods would not sample the ammonium chloride portion,
thus making the standard less stringent. You can obtain Administrator
approval for using Fourier Transform Infrared or Gas Filter Correlation
Infrared techniques following the provisions found in 40 CFR 63.7 if
those methods are found to pass a part 63, appendix A, Method 301
validation at the source.
---------------------------------------------------------------------------
\251\ After further review and consideration of the GFCIR Method
(322), we will not be promulgating its use in the Portland Cement
Kiln NESHAP rulemaking due to problems encountered with the method
during emission testing at lime manufacturing plants.
---------------------------------------------------------------------------
Compliance with the particulate matter standards requires the use
of either Method 5 or Method 5i in 40 CFR part 60, appendix A. See a
related discussion of Method 5i in Part 5, section VII.C.2.a of the
preamble to today's rule. Although Method 5i has better precision than
Method 5, your choice of methods depends on the emissions during the
performance test. In cases of low levels of particulate matter (i.e.,
for total train catches of less than 50 mg), we prefer that Method 5i
be used. For higher emissions, Method 5 may be used 252. In
practice this will likely mean that all incinerators and most
lightweight aggregate kilns will use Method 5i for compliance, while
some lightweight aggregate kilns and most cement kilns will use Method
5.
---------------------------------------------------------------------------
\252\ We note that this total train catch is not intended to be
a data acceptance criteria. Thus, total train catches exceeding 50
mg do not invalidate the method.
---------------------------------------------------------------------------
Today's rule also allows the use of any applicable SW-846 test
methods to demonstrate compliance with requirements of this subpart. As
an example, some commenters noted a preference to perform particulate
matter and hydrochloric acid tests together using Method 0050. Today's
rule would allow that practice. Applicable SW-846 test methods are
incorporated for use into today's rule via reference. See section
1208(a).
B. Sampling and Analysis of Feedstreams
Today's rule does not require the use of SW-846 methods for the
sampling and analysis of feedstreams. Consistent with our approach to
move toward performance based measurement
[[Page 52959]]
systems for other than method-defined parameters,253
today's rule allows the use of any reliable analytical method to
determine feedstream concentrations of metals, halogens, and other
constituents. It is your responsibility to ensure that the sampling and
analysis are unbiased, precise, and representative of the waste. For
the waste, you must demonstrate that: (1) Each constituent of concern
is not present above the specification level at the 80% upper
confidence limit around the mean; and (2) the analysis could have
detected the presence of the constituent at or below the specification
level at the 80% upper confidence limit around the mean. You can refer
to the Guidance for Data Quality Assessment--Practical Methods for Data
Analysis, EPA QA/G-9, January 1998, EPA/600/R-96/084 for more
information. Proper selection of an appropriate analytical method and
analytical conditions (as allowed by the scope of that method) are
demonstrated by adequate recovery of spiked analytes (or surrogate
analytes) and reproducible results. Quality control data obtained must
also reflect consistency with the data quality objectives and intent of
the analysis. You can read the January 31, 1996, memorandum from Barnes
Johnson, Director of the Economics, Methods, and Risk Assessment
Division, to James Berlow, Director of the Hazardous Waste Minimization
and Management Division for more information on this topic.
---------------------------------------------------------------------------
\253\ Feedstream sampling and analysis are not method defined
parameters.
---------------------------------------------------------------------------
IX. What Are the Reporting and Recordkeeping Requirements?
We discuss in this section reporting and recordkeeping requirements
and a provision in the rule for allowing data compression to reduce the
recordkeeping burden.
A. What Are the Reporting Requirements?
The reporting requirements of the rule include notifications and
reports that must be submitted to the Administrator as well as
notifications, requests, petitions, and applications that you must
submit to the Administrator only if you elect to request approval to
comply with certain reduced or alternative requirements. These
reporting requirements are summarized in the following tables. We
discuss previously in various sections of today's preamble the
rationale for additional or revised reporting requirements to those
currently required under subpart A of part 63 for all MACT sources. In
other cases, the reporting requirements for hazardous waste combustors
are the same as for other MACT sources (e.g., initial notification
under existing Sec. 63.9(b). We also show in the tables the
reference(s) in the regulations for the reporting requirement.
Summary of Notifications That You Must Submit to the Administrator
------------------------------------------------------------------------
Reference Notification
------------------------------------------------------------------------
63.9(b)................................ Initial notifications that you
are subject to Subpart EEE.
63.1210(b) and (c)..................... Notification of intent to
comply.
63.9(d)................................ Notification that you are
subject to special compliance
requirements.
63.1207(e), 63.9(e) 63.9(g) (1) and (3) Notification of performance
test and continuous monitoring
system evaluation, including
the performance test plan and
CMS performance evaluation
plan.
163.1210(d), 63.1207(j), 63.9(h), Notification of compliance,
63.10(d)(2), 63.10(e)(2). including results of
performance tests and
continuous monitoring system
performance evaluations.
63.1206(b)(6).......................... Notification of changes in
design, operation, or
maintenance.
63.9(j)................................ Notification and documentation
of any change in information
already provided under Sec.
63.9.
------------------------------------------------------------------------
\1\ You may also be required on a case-by-case basis to submit a
feedstream analysis plan under Sec. 63.1209(c)(3).
Summary of Reports That You Must Submit to the Administrator
------------------------------------------------------------------------
Reference Report
------------------------------------------------------------------------
63.1211(b)............................. Compliance progress report
associated and submitted with
the notification of intent to
comply.
63.10(d)(4)............................ Compliance progress reports, if
required as a condition of an
extension of the compliance
date granted under Sec.
63.6(i).
63.1206(c)(3)(vi)...................... Excessive exceedances reports.
63.1206(c)(4)(iv)...................... Emergency safety vent opening
reports.
63.10(d)(5)(i)......................... Periodic startup, shutdown, and
malfunction reports.
63.10(d)(5)(ii)........................ Immediate startup, shutdown,
and malfunction reports.
63.10(e)(3)............................ Excessive emissions and
continuous monitoring system
performance report and summary
report.
------------------------------------------------------------------------
Summary of Notifications, Requests, Petitions, and Applications That You
Must Submit to the Administrator Only if You Elect To Comply With
Reduced or Alternative Requirements
------------------------------------------------------------------------
Notification, request,
Reference petition, or application
------------------------------------------------------------------------
63.1206(b)(5), 63.1213, 63.6(i), You may request an extension of
63.9(c). the compliance date for up to
one year.
63.9(i)................................ You may request an adjustment
to time periods or postmark
deadlines for submittal and
review of required
information.
63.1209(g)(1).......................... You may request approval of:
(1) alternative monitoring
methods, except for standards
that you must monitor with a
continuous emission monitoring
system (CEMS) and except for
requests to use a CEMS in lieu
of operating parameter limits;
or (2) a waiver of an
operating parameter limit.
63.1209(a)(5), 63.8(f)................. You may request: (1) approval
of alternative monitoring
methods for compliance with
standards that are monitored
with a CEMS; and (2) approval
to use a CEMS in lieu of
operating parameter limits.
[[Page 52960]]
63.1204(d)(4).......................... Notification that you elect to
comply with the emission
averaging requirements for
cement kilns with in-line raw
mills.
63.1204(e)(4).......................... Notification that you elect to
comply with the emission
averaging requirements for
preheater or preheater/
precalciner kilns with dual
stacks.
63.1206(b)(1)(ii)(A)................... Notification that you elect to
document compliance with all
applicable requirements and
standards promulgated under
authority of the Clean Air
Act, including Sections 112
and 129, in lieu of the
requirements of Subpart EEE
when not burning hazardous
waste.
63.1206(b)(9)(iii)(B).................. If you elect to conduct
particulate matter CEMS
correlation testing and wish
to have federal particulate
matter and opacity standards
and associated operating
limits waived during the
testing, you must notify the
Administrator by submitting
the correlation test plan for
review and approval.
63.1206(b)(10)......................... Owners and operators of
lightweight aggregate kilns
may request approval of
alternative emission standards
for mercury, semivolatile
metal, low volatile metal, and
hydrochloric acid/chlorine gas
under certain conditions.
63.1206(b)(11)......................... Owners and operators of cement
kilns may request approval of
alternative emission standards
for mercury, semivolatile
metal, low volatile metal, and
hydrochloric acid/chlorine gas
under certain conditions.
63.1207(c)(2).......................... You may request to base initial
compliance on data in lieu of
a comprehensive performance
test.
63.1207(i)............................. You may request up to a one-
year time extension for
conducting a performance test
(other than the initial
comprehensive performance
test) to consolidate testing
with other state or federally-
required testing.
63.1209(l)(1).......................... You may request to extrapolate
mercury feedrate limits.
63.1209(n)(2)(ii)...................... You may request to extrapolate
semivolatile and low volatile
metal feedrate limits.
63.10(e)(3)(ii)........................ You may request to reduce the
frequency of excess emissions
and CMS performance reports.
63.10(f)............................... You may request to waive
recordkeeping or reporting
requirements.
63.1211(e)............................. You may request to use data
compression techniques to
record data on a less frequent
basis than required by Sec.
63.1209.
------------------------------------------------------------------------
Some commenters suggest that the rule needs to provide additional
reporting of information regarding metals fed to cement kilns,
including quarterly reporting of daily average metal feedrates, maximum
hourly feedrates, and all testing and analytical information on the
toxic metal content of cement kiln dust and clinker product. Also, they
suggest that toxic metals that are Toxics Release Inventory pollutants
and that are released to the land from cement kiln dust disposal should
be reported. While these reports might have some value for other
purposes, we must carefully scrutinize all reporting and recordkeeping
burdens for a rulemaking and determine whether the reporting and
recordkeeping requirements are necessary to ensure compliance with the
standards. (We, as an agency, cannot increase overall our reporting and
recordkeeping burden.)
We do not believe that these reports are needed to ensure
compliance with the standards and therefore are not requiring them. On
balance, quarterly filing requirements would be too burdensome. A
source must document compliance with all operating parameter limits and
emission standards at all times, and its records are subject to
inspection at any time. There is no additional need to provide
quarterly reports.
One commenter suggests that the proposed rule incorrectly focuses
on maximizing data collection as opposed to ensuring performance, thus
frustrating the use of better technology and methods. We, of course,
are also interested in ensuring performance by all reasonable means,
which for example accounts for our continued focus on continuous
emission monitors. However, we are not able to sacrifice data
collection as a means for ensuring compliance as well as a means to
undergird future rulemakings, assess achievability, and determine site-
specific compliance limits, where necessary.
B. What Are the Recordkeeping Requirements?
You must keep the records summarized in the table below for at
least five years from the date of each occurrence, measurement,
maintenance, corrective action, report, or record. See existing
Sec. 63.10(b)(1). At a minimum, you must retain the most recent two
years of data on site. You may retain the remaining three years of data
off site. You may maintain such files on: microfilm, a computer,
computer floppy disks, optical disk, magnetic tape, or microfiche.
We discuss previously in various sections of today's preamble the
rationale for additional or revised recordkeeping requirements to those
currently required under subpart A of part 63 for all MACT sources. In
other cases, the recordkeeping requirements for hazardous waste
combustors are the same as for other MACT sources (e.g., record of the
occurrence and duration of each malfunction of the air pollution
control equipment; see existing Sec. 63.10(b)(2)(ii)). We also show in
the table the reference(s) in the regulations for the recordkeeping
requirement.
[[Page 52961]]
Summary of Documents, Data, and Information That You Must Include in the
Operating Record
------------------------------------------------------------------------
Reference Document, data, or information
------------------------------------------------------------------------
63.1201(a), 63.10 (b) and (c).......... General. Information required
to document and maintain
compliance with the
regulations of Subpart EEE,
including data recorded by
continuous monitoring systems
(CMS), and copies of all
notifications, reports, plans,
and other documents submitted
to the Administrator.
63.1211(d)............................. Documentation of compliance.
63.1206 (c)(3)(vii).................... Documentation and results of
the automatic waste feed
cutoff operability testing.
63.1209 (c)(2)......................... Feedstream analysis plan.
63.1204 (d)(3)......................... Documentation of compliance
with the emission averaging
requirements for cement kilns
with in-line raw mills.
63.1204 (e)(3)......................... Documentation of compliance
with the emission averaging
requirements for preheater or
preheater/precalciner kilns
with dual stacks.
63.1206(b)(1) (ii)(B).................. If you elect to comply with all
applicable requirements and
standards promulgated under
authority of the Clean Air
Act, including Sections 112
and 129, in lieu of the
requirements of Subpart EEE
when not burning hazardous
waste, you must document in
the operating record that you
are in compliance with those
requirements.
63.1206 (c)(2)......................... Startup, shutdown, and
malfunction plan.
63.1206(c) (3)(v)...................... Corrective measures for any
automatic waste feed cutoff
that results in an exceedance
of an emission standard or
operating parameter limit.
63.1206(c) (4)(ii)..................... Emergency safety vent operating
plan.
63.1206 (c)(4)(iii).................... Corrective measures for any
emergency safety vent opening.
63.1206 (c)(6)......................... Operator training and
certification program.
63.1209 (k)(6)(iii), 63.1209 Documentation that a substitute
(k)(7)(ii), 63.1209 (k)(9)(ii), activated carbon, dioxin/furan
63.1209 (o)(4)(iii). formation reaction inhibitor,
or dry scrubber sorbent will
provide the same level of
control as the original
material.
------------------------------------------------------------------------
Some commenters are concerned that the specification of media on
which these files may be maintained unnecessarily limits the options to
facilities, especially those not equipped with computer or other
electronic data gathering equipment. We conclude, however, that the
options listed under Sec. 63.10(b)(1) seem to provide the greatest
flexibility possible, including the reasonable management of paper
records through the use of microfilm or microfiche. We encourage the
use of computer and electronic equipment, however, for logistical
reasons (retrieval and inspection can be easier) and as a means to
enhance dissemination to the local community to foster an atmosphere of
full and open disclosure about facility operations.
C. How Can You Receive Approval to Use Data Compression Techniques?
You may submit a written request to the Administrator under
Sec. 63.1211(f) for approval to use data compression techniques to
record data from CMS, including CEMS, on a frequency less than that
required by Sec. 63.1209. You must submit the request for review and
approval as part of the comprehensive performance test plan. For each
CEMS or operating parameter for which you request to use data
compression techniques, you must provide: (1) A fluctuation limit that
defines the maximum permissible deviation of a new data value from a
previously generated value without requiring you to revert to recording
each one-minute average; and (2) a data compression limit defined as
the closest level to an operating parameter limit or emission standard
at which reduced recording is allowed.
You must record one-minute average values at least every ten
minutes. If after exceeding a fluctuation limit you remain below the
limit for a ten-minute period, you may reinitiate your data compression
technique provided that you are not exceeding the data compression
limit.
The fluctuation limit should represent a significant change in the
parameter measured, considering the range of normal values. The data
compression limit should reflect a level at which you are unlikely to
exceed the specific operating parameter limit or emission standard,
considering its averaging period, with the addition of a new one-minute
average.
We provide the following table of recommended fluctuation and data
compression limits as guidance. These are the same limits that we
discussed in the May 1997 NODA.
Recommended Fluctuation and Data Compression Limits
----------------------------------------------------------------------------------------------------------------
Fluctuation limit () Data compression limit
----------------------------------------------------------------------------------------------------------------
Continuous Emission Monitoring System:
Carbon monoxide........................ 10 ppm....................... 50 ppm.
Hydrocarbon............................ 2 ppm........................ 60% of standard.
Combustion Gas Temperature Quench: Maximum 10 deg.F..................... Operating parameter limit (OPL)
inlet temperature for dry particulate minus 30 deg.F.
matter control device or, for lightweight
aggregate kilns, temperature at kiln exit.
Good Combustion Practices:
Maximum gas flowrate or kiln production 10% of OPL................... 60% of OPL.
rate.
Maximum hazardous waste feedrate....... 10% of OPL................... 60% of OPL.
Maximum gas temperature for each 20 deg.F..................... OPL plus 50 deg.F.
combustion chamber.
Activated Carbon Injection:
Minimum carbon injection feedrate...... 5% of OPL.................... OPL plus 20%.
Minimum carrier fluid flowrate or 20% of OPL................... OPL plus 25%.
nozzle pressure drop.
Activated Carbon Bed: Maximum gas 10 deg.F..................... OPL minus 30 deg.F.
temperature at inlet or exit of the bed.
Catalytic Oxidizer:
Minimum flue gas temperature at 20 deg.F..................... OPL plus 40 deg.F.
entrance.
Maximum flue gas temperature at 20 deg.F..................... OPL minus 40 deg.F.
entrance.
Dioxin Inhibitor: Minimum inhibitor 10% of OPL................... 60% of OPL.
feedrate.
Feedrate Control:
[[Page 52962]]
Maximum total metals feedrate (all 10% of OPL................... 60% of OPL.
feedstreams).
Maximum low volatile metals feedrate, 10% of OPL................... 60% of OPL.
pumpable feedstreams.
Maximum total ash feedrate (all 10% of OPL................... 60% of OPL.
feedstreams).
Maximum total chlorine feedrate (all 10% of OPL................... 60% of OPL.
feedstreams).
Wet scrubber:
Minimum pressure drop across scrubber.. 0.5 inches water............. OPL plus 2 inches water.
Minimum liquid feed pressure........... 20% of OPL................... OPL plus 25%.
Minimum liquid pH...................... 0.5 pH unit.................. OPL plus 1 pH unit.
Maximum solids content in liquid....... 5% of OPL.................... OPL minus 20%.
Minimum blowdown (liquid flowrate)..... 5% of OPL.................... OPL plus 20%.
Minimum liquid flowrate or liquid 10% of OPL................... OPL plus 30%.
flowrate/gas flowrate ratio.
Dry scrubber:
Minimum sorbent feedrate............... 10% of OPL................... OPL plus 30%.
Minimum carrier fluid flowrate or 10% of OPL................... OPL plus 30%.
nozzle pressure drop.
Fabric filter: Minimum pressure drop across 1 inch water................. OPL plus 2 inches water.
device.
Electrostatic precipitator and ionizing wet 5% of OPL.................... OPL plus 20%.
scrubber: Minimum power input (kVA:
current and voltage).
----------------------------------------------------------------------------------------------------------------
Data compression is the process by which a facility automatically
evaluates whether a specific data point needs to be recorded. Data
compression does not represent a change in the continuous monitoring
requirement in the rule. One-minute averages will continue to be
generated. With data compression, however, each one-minute average is
automatically compared with a set of specifications (i.e., fluctuation
limit and data compression limit) to determine whether it must be
recorded. New data are recorded when the one-minute average value falls
outside these specifications.
We did not propose data compression techniques in the April 1996
NPRM. In response to the proposed monitoring and recording
requirements, however, commenters raise concerns about the burden of
recording one-minute average values for the array of operating
parameter limits that we proposed. Commenters suggest that allowing
data compression would significantly reduce the recordkeeping burden
while maintaining the integrity of the data for compliance monitoring.
We note that data compression should also benefit regulatory officials
by allowing them to focus their review on those data that are
indicative of nonsteady-state operations and that are close to the
operating parameter limit or, for CEMS, the emission standard.
In response to these concerns, we presented data compression
specifications in the May 1997 NODA. Public comments on the NODA are
uniformly favorable. Therefore, we are including a provision in the
final rule that allows you to request approval to use data compression
techniques. The fluctuation and data compression limits presented above
are offered as guidance to assist you in developing your recommended
data compression methodology.
We are not promulgating data compression specifications because the
dynamics of monitored parameters are not uniform across the regulated
universe. Thus, establishing national specifications would be
problematic. Various data compression techniques can be successfully
implemented for a monitored parameter to obtain compressed data that
reflect the performance on a site-specific basis. Thus, the rule
requires you to recommend a data compression approach that addresses
the specifics of your operations. The fluctuation and data compression
limits presented above are offered solely as guidance and are not
required.
The rule requires that you record a value at least once every ten
minutes to ensure that a minimum, credible data base is available for
compliance monitoring. If you operate under steady-state conditions at
levels well below operating parameter limits and CEMS-monitored
emission standards, data compression techniques may enable you to
achieve a potential reduction in data recording up to 90 percent.
X. What Special Provisions Are Included in Today's Rule?
A. What Are the Alternative Standards for Cement Kilns and Lightweight
Aggregate Kilns?
In the May 1997 NODA, we discussed alternative standards for cement
kilns and lightweight aggregate kilns that have metal or chlorine
concentrations in their mineral and related process raw materials that
might cause an exceedance of today's standard(s), even though the
source uses MACT control. (See 62 FR 24238.) After carefully
considering commenters input, we adopt a process that allows sources to
petition the Administrator for alternative mercury, semivolatile metal,
low volatile metal, or hydrochloric acid/chlorine gas standards under
two different sets of circumstances. One reason for a source to
consider a petition is when a kiln cannot achieve the standard, while
using MACT control, because of raw material contributions to their
hazardous air pollutant emissions. The second reason is limited to
mercury, and applies when mercury is not present at detectable levels
in the source's raw material. These alternative standards are discussed
separately below.
1. What Are the Alternative Standards When Raw Materials Cause an
Exceedance of an Emission Standard? See sections 1206(b) (10) and (11)
a. What Approaches Have We Publicly Discussed? We acknowledge that
a kiln using properly designed and operated MACT control technologies,
including control of metals levels in hazardous waste feedstocks, may
not be capable of achieving the emission standards (i.e., the mercury,
semivolatile metal, low volatile metal, and/or hydrochloric acid/
chlorine gas standards). This can occur when hazardous air pollutants
(i.e., metals and chlorine) contained in the raw material volatilize or
are entrained in the flue gas such that their contribution to total
metal and chlorine emissions cause an exceedance of the emission
standard.
Our proposal first acknowledged this possible situation. In the
April 1996 NPRM, we proposed metal and chlorine standards that were
based, in part, on specified levels of hazardous waste feedrate control
as MACT control. To address our concern that kilns may not
[[Page 52963]]
be able to achieve the standards when using MACT control technologies,
given raw material contributions to emissions, we performed an
analysis. Our analysis estimated the total emissions of each kiln
including emissions from raw materials, while also assuming the source
was using MACT hazardous waste feedrate and particulate matter control.
Results of this analysis, which were discussed in the proposal,
indicated that there may be several kilns that would not be able to
achieve the proposed emission standards while using MACT control, due
to levels of metals and chlorine in raw material and/or conventional
fuel. (See 61 FR at 17393-17406.) Commenters requested that we provide
an equivalency determination to allow sources to comply with a control
efficiency requirement (e.g., a minimum metal system removal
efficiency) in lieu of the emission standard. (See response below.)
In the May 1997 NODA, we discussed revised standards that defined
MACT control, in part, based on hazardous waste metal and chlorine
feedrate control--as did the NPRM. (See 62 FR 24225-24235.) However,
our revised approach did not define specific levels of hazardous waste
metal and chlorine feedrate control, therefore, making it difficult to
attribute a kiln's failure to meet emission standards to metals levels
in raw materials.254 In response to a commenter's request,
we discussed, in the May 1997 NODA, an alternative approach to address
raw material contributions. Our approach did not subject a source to
the MACT standards if the source could document that metal or chlorine
concentrations in their hazardous waste, and any nonmineral feedstock,
is within the range of normal industry levels. The purpose of this
requirement was to ensure that metal and chlorine emissions
attributable to nonmineral feedstreams were roughly equivalent to those
from sources achieving the MACT emission standards. The use of an
industry average, or normal metal and chlorine level, was to serve as a
surrogate MACT feedrate control level for the alternative standard
because we did not define a specific level of control as MACT. We also
requested comment on how best to determine normal hazardous waste metal
and chlorine levels.
---------------------------------------------------------------------------
\254\ We could not estimate a cement kiln's total emissions
(i.e., to determine emission standard achievability) based on the
assumption that the kiln is feeding metals in the hazardous waste at
the MACT control feedrate levels.
---------------------------------------------------------------------------
Today's final rule uses a revised standard setting methodology that
defines specific levels of hazardous waste metal and chlorine feedrates
as MACT control.255 As a result, we do not need to define
normal, or average, metal and chlorine levels for the purposes of this
alternative standard provision.
---------------------------------------------------------------------------
\255\ As explained earlier, the emission standards for metals
and chlorine reflect the performance of MACT control, which includes
control of metals and chlorine in the hazardous waste feed
materials. As further explained, sources are not required to adopt
MACT control. Sources must, however, achieve the level of
performance which MACT control achieves. Therefore, sources are not
required to control metals and chlorine hazardous waste feedrates to
the same levels as MACT control in order to comply with the
standards for metals and chlorine. Rather, the source can elect to
achieve the emission standard by any means, which may or may not
involve hazardous waste feedrate control
---------------------------------------------------------------------------
b. What Comments Did We Receive on Our Approaches? There were many
comments supporting and many opposing the concept of allowing
alternative standards. Several commenters focus on the Agency's legal
basis for this type of alternative standard. Some, supporting an
alternative standard, wrote that feedrate control of raw materials at
mineral processing plants is not a permissible basis for MACT control.
In support of their position, some directed our attention to the
language found in the Conference Report to the 1990 CAA
amendments.256 However, as we noted in the April 1996 NPRM
and as was mentioned by many commenters 257, the Conference
Report language is not reflected in the statute. Section 112(d)(2)(A)
of the statute states, without caveat, that MACT standards may be based
on ``process changes, substitution of materials or other
modifications.''
---------------------------------------------------------------------------
\256\ H.R. Rep. No. 101-952, at p. 339, 101st Cong., 2d Sess.
(Oct. 26, 1990).
\257\ See 62 FR 24239, May 2, 1997.
---------------------------------------------------------------------------
As noted above, our MACT approach in today's rule relies on metal
and chlorine hazardous waste feedrate control as part of
developing MACT emission standards. It should be noted, that we do not
directly regulate raw material metal and chlorine input under this
approach, although there is no legal bar for us to do so. Since raw
material feedrate control is not an industry practice, raw material
feedrate control is not part of the MACT floor. In addition, we do not
adopt such control as a beyond-the-floor standard. We conclude it is
not cost-effective to require kilns to control metal and chlorine
emissions by substituting their current raw materials with off-site raw
materials. (See metal and chlorine emission standard discussions for
cement kilns and lightweight aggregate kilns in Part Four, Sections VII
and VIII.) 258
---------------------------------------------------------------------------
\258\ The nonhazardous waste Portland Cement Kiln MACT
rulemaking likewise controls semivolatile metal and low volatile
metal emissions by limiting particulate matter emissions, and did
not adopt beyond-the-floor standards based on raw material metal and
chlorine feedrate control--see 64 FR 31898.
---------------------------------------------------------------------------
Although today's rule offers a petition process, we considered
varying levels of metal and chlorine emissions attributable to raw
material in identifying the metal and chlorine emission standards
through our MACT floor methodology. This consideration helps to ensure
that the emission standards are achievable for sources using MACT
control. Therefore, we anticipate very few sources, if any, will need
to petition the Administrator for alternative standards. However, it is
possible that raw material hazardous air pollutant levels, at a given
kiln location, could vary over time and preclude kilns from achieving
the emission standards. We believe, therefore, that it is appropriate
to adopt a provision to allow kilns to petition for alternative
standards so that future changes in raw material feedstock will not
prevent compliance with today's emission standards.
Other commenters believe that alternative standards are not
necessary because there are kilns with relatively high raw material
metal concentrations already achieving the proposed standards. To
address this point, and to reevaluate the ability of kilns to achieve
the emission standards without new control of metals and chlorine in
raw material and conventional fuel, we again estimated the total metal
and chlorine emissions, assuming each kiln fed metal and chlorine at
the defined MACT feedrate control levels.259
---------------------------------------------------------------------------
\259\ When estimating emissions, the Agency assumed the kiln was
feeding metals and chlorine in its hazardous waste at the lower of
the MACT defining maximum theoretical emission concentration levels
or the level actually demonstrated during its performance test. See
Final Technical Support Document for Hazardous Waste Combustor MACT
Standards, Volume II: Selection of MACT Standards and Technologies,
July 1999, for further discussion.
---------------------------------------------------------------------------
The following table summarizes the estimated achievability of the
emission standards assuming kilns used MACT control. Our analysis
determined achievability both at the emission standard and at the
design level--70 percent of the standard. (To ensure compliance most
kilns will ``design'' their system to operate, at a minimum, 30 percent
below the standard.) The table describes the number of test conditions
in our data base that would not meet the emission standard or meet the
design level by estimating total emissions. For example, all cement
kiln test conditions achieve the mercury emission standard, assuming
all cement
[[Page 52964]]
kilns used MACT control. On the other hand, the table also indicates
that four cement kiln test conditions out of 27 do not achieve the
design level for mercury. In our analysis, if all test conditions
achieved both the standard and the design level, we concluded that
there is no reason to believe raw material contributions to metal and
chlorine emissions might cause a compliance problem.
Cement Kiln and Lightweight Aggregate Kiln Emission Standard
Achievability Results
------------------------------------------------------------------------
Low
Source category Mercury Semivolatile Volatile Total
metal metal chlorine
------------------------------------------------------------------------
No. of cement kiln test \1\0/27 \1\1/38 \1\1/39 \1\2/42
conditions in MACT data base
not achieving standard......
No of cement kiln test 4/27 6/38 3/39 3/42
conditions in MACT data base
not achieving 70 % design
level.......................
No of lightweight aggregate 0/17 5/22 2/22 3/18
kiln test conditions in MACT
data base not achieving
standard....................
No of lightweight aggregate 0/17 5/22 4/22 10/18
kiln test conditions in MACT
data base not achieving 70%
design level................
------------------------------------------------------------------------
*Number after slash denotes total number of test conditions.
Our analysis illustrates that, subject to the assumptions made,
some lightweight aggregate kilns and cement kilns have raw material
hazardous air pollutant levels that could affect their ability to
achieve the emission standard if no additional emission controls were
implemented (e.g., additional hazardous waste feedrate control, or
better air pollution control device efficiency). Nevertheless, we
conclude that it is difficult to determine whether raw material
hazardous air pollutant contributions to the emissions result in
unachievable emission standards because of the difficulty associated
with differentiating raw material hazardous air pollutant emissions
from hazardous waste pollutant emissions. This uncertainty has led us
to further conclude that it is appropriate to allow kilns to petition
for alternative standards, provided that they submit site-specific
information that shows raw material hazardous air pollutant
contributions to the emissions prevent the kiln from complying with the
emission standard even though the kiln is using MACT control.
Many commenters dislike the idea of an alternative standard. They
wrote that regulation of raw material metal content may be necessary to
control semivolatile metal and low volatile metal emissions at
hazardous waste burning kilns because: (1) These kilns have relatively
high chlorine levels in the flue gas (which predominately originate
from the hazardous waste); and (2) chlorine tends to increase metal
volatility. We agree that increased flue gas chlorine content from
hazardous waste burning operations may result in increased metals
volatility, which then could result in higher raw material metal
emissions.260 The increased presence of chlorine at
hazardous waste burning kilns presents a concern. To address this
concern, we require kilns to submit data or information, as part of the
alternative standard petition, documenting that increased chlorine
levels associated with the burning of hazardous waste, as compared to
nonhazardous waste operations, do not significantly increase metal
emissions attributable to raw material. This requirement is explained
in greater detail later in this section.
---------------------------------------------------------------------------
\260\ The potential for increased metal emissions is stronger
for semivolatile metals (lead, in particular), but low volatile
metal emissions still have potential to increase with increased flue
gas chlorine concentrations. See Final Technical Support Document
for Hazardous Waste Combustor MACT Standards, Volume II: Selection
of MACT Standards and Technologies, July 1999, for further
discussion.
---------------------------------------------------------------------------
Many commenters also point out that the alternative standard, at
least as originally proposed, could result in metal and chlorine
emissions exceeding the standard to possible levels of risk to human
health and the environment. We agree that this potential could exist;
however, the RCRA omnibus process serves as a safeguard against levels
of emissions that present risk to human health or the environment.
Therefore, sources operating pursuant to alternative standards may
likely be required to perform a site-specific risk assessment to
demonstrate that their emissions do not pose an unacceptable risk. The
results of the risk assessment would then be used to develop facility-
specific metal and chlorine emission limits (if necessary), which would
be implemented and enforced through omnibus conditions in the RCRA
permit.261
---------------------------------------------------------------------------
\261\ RCRA permits for hazardous waste combustors address total
emissions, regardless of the source of the pollutant due to the
nexus with the hazardous waste treatment activities. See Horsehead v
Browner, 16 F. 3d 1246, 1261-63 (D.C. Cir. 1994)(Hazardous waste
combustion standards may address hazardous constituents attributable
to raw material inputs so long as thee is a reasonable nexus with
the hazardous waste combustion activites).
---------------------------------------------------------------------------
c. How Do I Demonstrate Eligibility for the Alternative Standard?
To demonstrate eligibility, you must submit data or information which
shows that raw material hazardous air pollutant contributions to the
emissions prevent you from complying with the emission standard, even
though you use MACT control for the standard from which you seek
relief. To allow flexibility in implementation, we do not mandate what
this demonstration must entail. However, we believe that a
demonstration should include a performance test while using MACT
control or better (i.e., the hazardous waste feedrate control and air
pollution control device efficiencies that are the basis of the
emission standard from which you seek an alternative). If you still do
not achieve the emission standards when operating under these
conditions, you may be eligible for the alternative standard (provided
you further demonstrate that you meet the additional eligibility
requirements discussed below). If you choose to conduct this
performance test after your compliance date, you should first obtain
approval to temporarily exceed the emission standards (for testing
purposes only) to make this demonstration, otherwise you may be subject
to enforcement action.
In addition, you must make a showing of adequate system removal
efficiency to be eligible for an alternative standard for semivolatile
metal, low volatile metal, or hydrochloric acid/chlorine gas. This
requirement provides a check to ensure that you are exceeding the
emission standard solely because of raw material contributions to the
emissions, and not because of poor system removal efficiency for the
hazardous air pollutants for which you are seeking relief. (It is
possible that poor system removal efficiencies for these hazardous air
pollutants result in emissions that are higher than the emission
standards, even though the particulate matter emission standard is
met.) This check could be done without the expense of a second
performance test. The system removal efficiency achieved in the
performance test described above could be calculated for the hazardous
air pollutants at issue. You would then
[[Page 52965]]
multiply the MACT control hazardous waste feedrate level (or the
feedrate level you choose to comply with) 262 for the same
hazardous air pollutant by a factor of one minus the system removal
efficiency. This estimated emission value would then be compared to the
emission standard, and would have to be below the standard for you to
qualify for the alternative standard.
---------------------------------------------------------------------------
You may choose to comply with a hazardous waste feedrate limit
that is lower than the MACT control levels required by this
alternative standard.
---------------------------------------------------------------------------
As discussed in the next section, this alternative standard
requires you to use MACT control as defined in this rulemaking. For
lightweight aggregate kilns, MACT control for chlorine is feedrate
control and use of an air pollution control system that achieves a
given system removal efficiency for chlorine. Thus, lightweight
aggregate kilns that petition the Administrator for an alternative
chlorine standard must also demonstrate, as part of a performance test,
that it achieves a specified minimum system removal efficiency for
chlorine. This eligibility requirement is identical to the above-
mentioned eligibility demonstration that requires sources to make a
showing of adequate system removal efficiency, with the exception that
here we specify the system removal efficiency that must be
achieved.263
---------------------------------------------------------------------------
\263\ The requirement to achieve an 85.0% and 99.6% chlorine
system removal efficiency for existing and new lightweight aggregate
kilns, respectively, together with the requirement to comply with a
hazardous waste chlorine feedrate limitation, ensures that chlorine
emissions attributable to hazardous waste are below the standards.
---------------------------------------------------------------------------
For an alternative mercury standard, you do not have to perform a
performance test demonstration and evaluation. We do not require this
test because the mandatory hazardous waste mercury feedrate specified
in Sec. 63.1206(b)(10) and (11) ensures that your hazardous waste
mercury contribution to the emissions will always be below the mercury
standard.264
---------------------------------------------------------------------------
\264\ The MACT defining hazardous waste maximum theoretical
emission concentration for mercury is less than mercury standard
itself, thus hazardous waste mercury contributions to the emissions
will always be below the standard.
---------------------------------------------------------------------------
Finally, if you apply for semivolatile metal or low volatile metal
alternative standards, you also must demonstrate, by submitting data or
information, that increased chlorine levels associated with the burning
of hazardous waste, as compared to nonhazardous waste operations, do
not significantly increase metal emissions attributable to raw
material. We expect that you will have to conduct two different
emission tests to make this demonstration (although the number of tests
should be determined on a site-specific basis). The first test is to
determine metal emission concentrations when the kiln is burning
conventional fuel with typical chlorine levels. The second test is to
determine metal emissions when chlorine feedrates are equivalent to
allowable chlorine feedrates when burning hazardous waste. You should
structure these tests so that metal feedrates for both tests are
equivalent. You would then compare metal emission data to determine if
increased chlorine levels significantly affects raw material metal
emissions.
d. What Is the Format of the Alternative Standard? The alternative
standard requires that you use MACT control, or better, as applicable
to the standard for which you seek the alternative. MACT control, as
previously discussed, consists of hazardous waste feed control plus
(for all relevant hazardous air pollutants except mercury) further
control via air pollution control devices. Cement kilns and lightweight
aggregate kilns will first have to comply with a specified hazardous
waste metal and chlorine feedrate limit, as defined by the MACT
defining maximum theoretical emission concentration level for the
applicable hazardous air pollutant or hazardous air pollutant group.
This work practice is necessary because there is no other reliable
means of measuring that hazardous air pollutants in hazardous waste are
controlled to the MACT control levels, i.e., that hazardous air
pollutants in raw material are the sole cause of not achieving the
emission standard. (See CAA section 112(h).) To demonstrate control of
hazardous air pollutant metals emissions to levels reflecting the air
pollution control device component of MACT control, you must be in
compliance with the particulate matter standard. Finally, we require
lightweight aggregate kilns to use an air pollution control device that
achieves the specified MACT control total chlorine removal efficiency.
This work practice is necessary because there is no other way to
measure whether the failure to achieve the chlorine emission standard
is caused by chlorine levels in raw materials.265 See
Sec. 63.1206(b)(10) and (11) for a list of the maximum achievable
control technology requirements for purposes of this alternative
standard.266
---------------------------------------------------------------------------
\265\ There is no corresponding chlorine air pollution control
device efficiency requirement for cement kilns since air pollution
control is not the basis for MACT control of cement kiln chlorine
emissions.
\266\ See also ``Final Technical Support Document for Hazardous
Waste Combustor MACT Standards, Volume IV: Selection of MACT
Standards and Technologies'', Chapter 11, July 1999, for further
discussion on how the maximum achievable control technologies were
chosen for the hazardous air pollutants.
---------------------------------------------------------------------------
There may be site-specific circumstances which require other
provisions, imposed by the Administrator, in addition to the mandatory
requirement to use MACT control. These provisions could be operating
parameter requirements such as a further hazardous waste feedrate
limitation. For instance, a kiln that petitions the Administrator for
an alternative semivolatile emission standard may need to limit its
hazardous waste chlorine feedrate to better assure that chlorine
originating from the hazardous waste does not significantly affect
semivolatile metal emissions attributable to the raw material. As
discussed above, a kiln must demonstrate that increased chlorine levels
from hazardous waste do not adversely affect raw material metal
emissions to be eligible for this alternative standard. For this
scenario, the alternative standard would be in the form of a
semivolatile metal hazardous waste feedrate restriction which would
require you to use MACT control, in addition to a hazardous waste
chlorine feedrate limit.
Additional provisions also could include emission limitations that
differ from those included in today's rulemaking. For example, the
Administrator may determine it appropriate to require you to comply
with metal or chlorine emission limitations that are than the standards
in this final rulemaking. The emission limitation would likely consider
the elevated levels of metal or chlorine in your raw material. This
type of emission limitation would be no different, except for the
numerical difference than the emission limitations in today's rule
because it would limit total metal and chlorine emissions while at the
same time ensuring MACT control is used. If the Administrator
determines that such an emission limitation is appropriate, you must
comply with both a hazardous waste feedrate restriction, which requires
you to use MACT control, and an emission limitation. A potential method
of determining an appropriate emission limitation would be to base the
limit on levels demonstrated in the comprehensive performance test.
e. What Is the Process for an Alternative Standard Petition? If you
are seeking alternative standards because raw materials cause you to
exceed the standards, you must submit a petition request to the
Administrator that includes your recommended alternative
[[Page 52966]]
standard provisions. At a minimum, your petition must include data or
information which demonstrates that you meet the eligibility
requirements and that ensure you use MACT control, as defined in
today's rule.
Until the authorized regulatory agency approves the provisions of
the alternative standard in your petition (or establishes other
alternative standards) and until you submit a revised NOC that
incorporates the revised standards, you may not operate under your
alternative standards in lieu of the applicable emission standards
found in Secs. 63.1204 and 63.1205. We recommend that you submit a
petition well in advance of your scheduled comprehensive performance
test, perhaps including the petition together with your comprehensive
performance test plan. You may need to submit this petition in phases
to ultimately receive approval to operate pursuant to the alternative
standard provisions, similar to the review process associated with
performance test workplans and performance test reports. After initial
approval, alternative standard petitions should be resubmitted every
five years for review and approval, concurrent with subsequent future
comprehensive performance tests, and should contain all pertinent
information discussed above.
You may find it necessary to complete any testing associated with
documenting your eligibility requirements prior to your comprehensive
performance test to determine if in fact you are eligible for this
alternative standard, or you may choose to conduct this testing at the
same time you conduct your comprehensive performance test. This should
be determined on a site-specific basis, and will require coordination
with the Administrator or Administrator's designee.
2. What Special Provisions Exist for an Alternative Mercury Standard
for Kilns?
See Sec. 63.1206(b)(10) and (11).
a. What Happens if Mercury Is Historically Not Present at
Detectible Levels? Situations may exist in which a kiln cannot comply
with the mercury standard pursuant to the provisions in Sec. 63.1207(m)
when using MACT control and when mercury is not present in the raw
material at detectable levels.267 As a result, today's rule
provides a petition process for an alternative mercury standard which
only requires compliance with a hazardous waste mercury feedrate
limitation, provided that historically mercury not been present in the
raw material at detectable levels.
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\267\ The provisions in Sec. 63.1207(m) waive the requirement
for you to conduct a performance test, and the requirement to set
operating limits based on performance test data, provided you
demonstrate that uncontrolled mercury emissions are below the
emission standard (see Part 4, Section X.B). These provisions allow
you to assume mercury is present at half the detection limit in the
raw material, when a feedstream analysis determines that mercury is
not present at detectable levels, when calculating your uncontrolled
emissions.
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We received comments from the lightweight aggregate kiln industry
expressing concern with the stringency of the mercury standard.
Commenters oppose stringent mercury standards, in part, because of the
difficulty of complying with day-to-day mercury feedrate limits. One
potential problem cited pertains to raw material mercury detection
limits. Commenters point out that if a kiln assumed mercury is present
in the raw material at the detection limit, the resulting calculated
uncontrolled mercury emission concentration could exceed, or be a
significant percentage of, the mercury emission standard. This may
prevent a kiln from complying with the mercury emission standard
pursuant to the provisions of Sec. 63.1207(m), even though MACT control
was used.
We agree with commenters that this is a potential problem. In
addition, it is not appropriate to implement a mercury standard
compliance scheme that is relatively more burdensome for kilns with no
mercury present in raw material, as compared to kilns with high levels
of mercury in their raw material.268 Because we establish
provisions that provide alternatives to kilns with high levels of
mercury in the raw material, we are doing the same for those kilns
which do not have mercury present in raw material at detectable levels.
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\268\ Kilns that comply with alternative mercury standards
because of high mercury levels in their raw material are not
required to monitor the mercury content of their raw material unless
the Administrator requires this as an additional alternative
standard requirement. Thus, absent the alternative mercury standard
discussed in this section, a source that does not have mercury
present in their mercury at detectable levels would be subject to
more burdensome raw material feedstream analysis requirements.
---------------------------------------------------------------------------
b. What Are the Alternative Standard Eligibility Requirements? To
be eligible for this alternative mercury standard, you must submit data
or information which demonstrates that historically mercury has not
been present in your raw material at detectable levels. You do not need
to show that mercury has never been present at detectable levels. The
determination of whether your data and information sufficiently
demonstrate that mercury has not historically been present in your raw
material at detectable levels will be made on a site-specific basis. To
assist in this determination, you also should provide information that
describes the analytical methods (and their associated detection
limits) used to measure mercury in the raw material, together with
information describing how frequently you measured raw material mercury
content.
If you are granted this alternative standard, you will not be
required to monitor mercury content in your raw material for compliance
purposes. However, after initial approval, this alternative standard
must be reapproved every five years (see discussion below). Therefore,
you should develop a raw material mercury sampling and analysis program
that can be used in future alternative mercury standard petition
requests for the purpose of demonstrating that mercury has not
historically been present in raw material at detectable levels.
c. What Is the Format of Alternative Mercury Standard? The
alternative standard requires you to use MACT control for mercury
(i.e., the level of hazardous waste feedrate control specified in
today's rule). This alternative standard for mercury is conceptually
identical to the emission standards in this final rule, because it
requires the use of an equivalent level of hazardous air pollutant MACT
control as compared to the MACT control used to determine the emission
standards.
The mercury feedrate control level will differ for new and existing
sources, and will differ for cement kilns and lightweight aggregate
kilns. See Sec. 63.1206(b) (10) and (11) for a list of the mercury
hazardous waste feedrate control levels for purposes of this
alternative standard.269
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\269\ Also see Final Technical Support Document for Hazardous
Waste Combustor MACT Standards, Volume IV: Selection of MACT
Standards and Technologies, Chapeter 11, July 1999, for further
discussion on how the maximum achievable control technologies were
chosen for mercury.
---------------------------------------------------------------------------
d. What Is the Process for The Alternative Mercury Standard
Petition? If you are seeking this alternative mercury standard, you
must submit a petition request to the Administrator that includes the
required information discussed above. You will not be allowed to
operate under this alternative standard, in lieu of the applicable
emission standards found in Secs. 63.1204 and 63.1205, unless and until
the Administrator approves the provisions of this alternative standard
and until you submit a revised NOC that incorporates this alternative
standard.
[[Page 52967]]
We recommend that you submit these petitions well in advance of your
scheduled comprehensive performance test, perhaps including the
petition together with your comprehensive performance test plan. After
initial approval, alternative standard petitions should be resubmitted
every five years for review and approval, concurrent with subsequent
future comprehensive performance tests, and should contain all
pertinent information discussed above.
B. Under What Conditions Can the Performance Testing Requirements Be
Waived? See Sec. 63.1207(m).
In the April 1996 NPRM, we proposed a waiver of performance testing
requirements for sources that feed low levels of mercury, semivolatile
metal, low volatile metal, or chlorine (see 61 FR at 17447). Under the
proposed waiver, a source would be required to assume that all mercury,
semivolatile metal, low volatile metal, or chlorine (dependent on which
hazardous air pollutant(s) the source wishes to petition for a waiver)
fed to the combustion unit, for all feedstreams, is emitted from the
stack. The source also would need to show that these uncontrolled
emission concentrations do not exceed the associated emission
standards, taking into consideration stack gas flow rate. The above
requirements would apply for all periods that a source elects to
operate under this waiver and for which the source is subject to the
requirements of this rulemaking. All comments received on this topic
support this approach, and no commenters suggest alternative procedures
to implement this provision. Today's rule finalizes the proposed
performance test waiver provision, with one minor change expected to
provide industry with greater flexibility when demonstrating compliance
without compromising protectiveness.
1. How Is This Waiver Implemented?
The April 1996 proposal identified two implementation methods to
document compliance with this waiver provision. In today's rule we
finalize both proposed methods and add another implementation method to
provide greater flexibility when demonstrating compliance with the
provisions of this performance test waiver. As proposed, the first
approach allows establishment and continuous compliance with one
maximum total feedstream feedrate limit for mercury, semivolatile
metal, low volatile metal, or chlorine and one minimum stack gas flow
rate. The combined maximum feedrate and minimum stack gas flow rate
must result in uncontrolled emissions below the applicable mercury,
semivolatile metal, low volatile metal, or chlorine emission standards.
Both limits would be complied with continuously; any exceedance would
require the initiation of an automatic waste feed cut-off.
Also as proposed, the second approach accommodates operation under
different ranges of stack gas flow rates and/or metal and chlorine
feedrates. Today's rule allows establishment of different modes of
operation with corresponding minimum stack gas flow rate limits and
maximum feedrates for metals or chlorine. If you use this approach, you
must clearly identify in the operating record which operating mode is
in effect at all times, and you must properly adjust your automatic
waste feed cutoff levels accordingly.
The third approach, which is an outgrowth of our proposed
approaches, allows continuous calculation of uncontrolled stack gas
emissions, assuming all metals or chlorine fed to combustion unit are
emitted out the stack. If you use this approach, you must record these
calculated values and comply with the mercury, semivolatile metal, low
volatile metal, or chlorine emission standards on a continuous basis.
This approach provides greater operational flexibility, but increases
recordkeeping since the uncontrolled emission level must be
continuously recorded and included in the operating record for
compliance purposes.
If you claim this waiver provision, you must, in your performance
test workplan, document your intent to use this provision and explain
which implementation approach is used. Other than those limits required
by this provision, you will not be required to establish or comply with
operating parameter limits associated with the metals or chlorine for
which the waiver is claimed. Your NOC also must specify which
implementation method is used. The NOC must incorporate the minimum
stack gas flowrate and maximum metal and chlorine feedrate as operating
parameter limits, or include a statement which specifies that you will
comply with emission standard(s) by continuously recording your
uncontrolled metal and chlorine emission rate.
If you cannot continuously monitor stack gas flow rate, for the
purpose of demonstrating compliance with the provisions of this waiver,
you may use an appropriate surrogate in place of stack gas flow rate
(e.g., cement kiln production rate). However, if you use a surrogate,
you must provide in your performance test workplan data that clearly
and reasonably correlates the surrogate parameter to stack gas flow
rate.
2. How Are Detection Limits Handled Under This Provision?
We did not address in April 1996 NPRM how nondetect metal and
chlorine feedstream results are handled when demonstrating compliance
with the feedrate limits or when calculating uncontrolled emission
concentrations under this provision. Commenters likewise did not offer
suggestions of how to handle nondetect data for this provision. After
careful consideration, for the purposes of this waiver, we require that
you must assume that the metals and chlorine are present at the full
detection limit value when the analysis determines the metals and
chlorine are not detected in the feedstream (except as described in the
following paragraph). Because performance testing is waived under this
provision, it is appropriate to adopt a more conservative assumption
that metals and chlorine are present at the full detection limit for
the purposes of this waiver. (In other portions of today's rule we make
the assumption that 50 percent presence is appropriate given the
different context involved). Assuming full detection limits provides an
additional level of assurance that resulting emissions still reflect
MACT and do not pose a threat to human health and the environment. If
you cannot demonstrate compliance with the provisions of this waiver
when assuming full detection limits, then you should not claim this
waiver and should conduct emissions testing to demonstrate compliance
with the emission standard.
Based on the comments and as discussed in the previous section
(Section A.2.a), we conclude it is not appropriate, for purposes of
this performance test waiver provision, to require a kiln to assume
mercury is present at the full detection limit in its raw material when
the feedstream analysis determines mercury is not present at detectable
levels. As a result, we allow kilns to assume mercury is present at
one-half the detection limit in raw materials when demonstrating
compliance with the performance test waiver provisions whenever the raw
material feedstream analysis determines that mercury is not present at
detectable levels.
C. What Other Waiver Was Proposed, But Not Adopted?
Waiver of the Mercury, Semivolatile Metal, Low Volatile Metal, or
Chlorine Standard
[[Page 52968]]
We proposed not to subject sources to one or more of the mercury,
semivolatile metal, low volatile metal, or chlorine emission standards
(and other requirements) 270 if their feedstreams did not
contain detectable levels of that associated metal or chlorine (e.g.,
if their feedstreams did not contain a detectable level of chlorine,
the hydrochloric acid/chlorine gas standard would be waived--see 61 FR
at 17447). As part of this waiver, a feedstream sampling and analysis
plan would be developed and implemented to document that feedstreams
did not contain detectable levels of the metals or chlorine.
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\270\ Ancillary performance testing, monitoring, notification,
record keeping, and reporting requirements.
---------------------------------------------------------------------------
Several commenters supported this waiver, stating that it is of no
benefit to human health or the environment to require performance
testing, monitoring, notification, and record-keeping of constituents
not fed to the combustion unit. However, commenters were divided in
their support of the need to set minimum feedstream detection limits.
Those supporting specified detection limits wrote that detection limits
are needed to ensure that appropriate analytical procedures are used
and needed to provide consistency between sources. Those opposing
specified detection limits believed that detection limits are highly
dependent on feedstream matrices. Therefore, to impose a detection
limit that applies to all sources and all feedstreams would not be
practicable. One commenter questioned basing this waiver on nondetect
values because a feedstream analyses that detects, at any time, a
quantity of the metal or chlorine just above the detection limit may be
considered to be out of compliance.
We agree that little or no environmental benefit may be gained by
requiring performance testing, monitoring, notification, and record
keeping for a constituent not fed to the combustion unit. However,
based on our careful analysis of comments and on our reevaluation of
the practical implementation issue inherent in this type of waiver, we
find that it may not always be practicable to use detection limits to
determine if a waste does or does not contain metals or chlorine. We
are concerned that facility-specific detection limits may vary, from
source to source, at levels such that sources with detection limits in
the high-end of the distribution (due to their complex waste matrix)
have the potential for significant metal or chlorine emissions. Under
the facility-specific detection limit approach, a high-end detection
limit source with relatively high emissions could qualify for the
waiver; however, a source with a simpler feedstream matrix with
significantly lower amounts of metals in the feedstream (but just above
the detection limit) would not qualify. This not only turns the
potential benefit of a waiver provision on its head, but raises serious
questions of national consistency, fairness, and evenness of
environmental protection to surrounding communities. We also conclude
that it is impractical to set one common detection limit for each
hazardous air pollutant as part of this waiver because, as commenters
stated, detection limits are matrix dependent.
Due to these issues, we were unable to devise an implementable and
acceptable nondetect waiver provision, and therefore do not adopt one
in today's final rule. As is described in the previous section (Section
B), however, we do provide a waiver of performance testing requirements
to sources that feed low levels of mercury, semivolatile metal, low
volatile metal, or chlorine. Although this waiver provision does not
waive the emission standard, monitoring, notification, recordkeeping,
and reporting requirements, it does waive emission tests and compliance
with operating parameter limits for the associated metals or chlorine.
D. What Equivalency Determinations Were Considered, But Not Adopted?
In response to comments we received from the April 1996 NPRM, we
included in the May 1997 NODA a discussion of an allowance of a one-
time compliance demonstration for hydrocarbon and carbon monoxide at
cement kilns equipped with temporary midkiln sampling locations. (See
62 FR 24239.) This equivalency determination required that alternative,
continuously monitored, operating parameters be used in lieu of
continuous monitoring of hydrocarbon/carbon monoxide. As discussed
below, we conclude that the shortcomings associated with the proposed
alternative operating parameters created sufficient uncertainties, for
implementation and overall environmental protection, that we are not
adopting an equivalency determination option in this rulemaking.
However, cement kilns have the opportunity to petition the
Administrator under Sec. 63.8(f) and 63.1209(g)(1) to make a site-
specific case for this type of equivalency determination.
In response to the April 1996 NPRM, we received comments indicating
that some kilns would need to either operate at inefficient back-end
temperatures (to oxidize hydrocarbons desorbed from the raw material)
or be required to install and maintain a midkiln sampling system to
demonstrate compliance with the hydrocarbon/carbon monoxide standards.
Commenters believe that this may not be feasible for some kilns
because: (1) Raising back end temperatures may increase dioxin
formation; (2) most long kilns are not equipped to sample emissions at
the midkiln location; (3) costs associated with retrofit and
maintenance may be considered high; and (4) maintenance problems
associated with the sampling duct are difficult to overcome.
We received numerous comments on the proposed hydrocarbon/carbon
monoxide equivalency approach described in the May 1997 NODA. Many
cement kilns support the option and defend the use of alternative
operating parameters in lieu of continuous carbon monoxide and
hydrocarbon monitors. Many commenters oppose using any parameters other
than carbon monoxide or hydrocarbon as a combustion efficiency
indicator and as surrogate emission standards for the nondioxin organic
hazardous air pollutants. We have found that a number of factors
suggest that a special provision allowing use of alternative operating
parameters, in lieu of carbon monoxide and/or hydrocarbon, is neither
necessary nor appropriate to include in this rulemaking.
The alternative operating parameters associated with a one-time
demonstration would have to assure that compliance with the carbon
monoxide/hydrocarbon standard is maintained at the midkiln location on
a continuous basis. We considered adopting several different operating
parameters in lieu of hydrocarbon/carbon monoxide monitoring to achieve
this goal. Maximum production rate was considered as a continuous
residence time indicator. Minimum combustion zone temperature,
continuously monitored destruction and removal efficiency using sulphur
hexafluoride, and minimum effluent NOX limits were also
examined to ensure adequate temperature is continuously maintained in
the combustion zone. To ensure adequate turbulence, we considered using
minimum kiln effluent oxygen concentration. Commenters did not suggest
additional alternative operating parameters.
Each of these operating parameters have potential shortcomings, and
we are not convinced that use of these parameters, even in combination,
provides a combustion efficiency indicator as reliable as continuous
[[Page 52969]]
hydrocarbon/carbon monoxide monitoring. We have identified the
following potential problems with these alternative operating
parameters: (1) Effluent kiln oxygen concentration may not correlate
well to carbon monoxide/hydrocarbon produced from oxygen deficient
zones in the kiln; 271,272 (2) pyrometers, or other
temperature monitoring systems, may not provide direct and reliable
measurements of combustion zone temperature; 273 (3) some
combustion products of sulphur hexaflouride are toxic and regulated
hazardous air pollutants; 274 (4) there are no demonstrated
performance specifications for continuous sulphur hexaflouride
monitors; and (5) it is contrary to other air emission limitations (in
principle) to require minimum (not maximum) NOX limits.
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\271\ An oxygen deficient zone in the kiln due to inadequate
mixing, which could potentially result in the emission of
significant amounts of carbon monoxide and organic hazardous air
pollutants, could be well mixed with excess air by the time it
reaches the kiln exit, where oxygen is monitored. Thus the oxygen
monitor may not record any oxygen concentration change and would not
serve as an adequate control to ensure proper combustion turbulence.
\272\ We do not have, nor did commenters submit, data which show
whether effluent kiln oxygen concentration adequately correlates
with carbon monoxide/hydrocarbon produced from oxygen deficient
zones in the kiln.
\273\ See Part Five, Section VII.D.(2)(b)(iii), for further
discussion on combustion zone temperature measurements.
\274\ Hydrofluoric acid, a CAA hazardous air pollutant, is a
possible combustion byproduct of sulphur hexafluoride.
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On balance, the lack of adequate documentation allowing us to
resolve these uncertainties and potential problem areas prevents us
from further considering this type of hydrocarbon/carbon monoxide
equivalency determination provision for inclusion in today's final
rule. As stated above, however, cement kilns have the opportunity to
petition the Administrator under Sec. 63.8(f) to make a site-specific
case for this type of equivalency determination.
As is explained in Part Four, Section VII.C(9)(c), today's
rulemaking subjects newly constructed hazardous waste burning cement
kilns at greenfield sites to a main stack hydrocarbon standard of
either 20 or 50 ppmv. We clarify that this standard applies to these
sources even if they applied and received approval for an alternative
monitoring approach described above, because the intent of this
hydrocarbon standard is to control organic hazardous air pollutants
desorbed from raw material and not to control combustion efficiency.
E. What are the Special Compliance Provisions and Performance Testing
Requirements for Cement Kilns with In-line Raw Mills and Dual Stacks?
Preheater/precalciner cement kilns with dual stacks and cement
kilns with in-line raw mills require special compliance provisions and
performance testing requirements because they are unique in design.
Preheater/precalciner kilns with dual stacks have two separate air
pollution control systems. As discussed in Section F below, emission
characteristics from these separate stacks could be different. As a
result, these kilns must conduct emission testing in both stacks to
document compliance with the emission standards 275 and must
establish separate operating parameter limits for each air pollution
control device. See Sec. 63.1204(e)(1).
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\275\ This does not apply to the hydrocarbon and carbon monoxide
standard. See discussion in Part Four, Section VII.D on hydrocarbon
and carbon monoxide standards for cement kilns.
---------------------------------------------------------------------------
Cement kilns with in-line raw mills either operate with the raw
mill on-line or with the raw mill off-line. As discussed in Section F
below, these two different modes of operation could have different
emission characteristics. As a result, cement kilns with in-line raw
mills must conduct emission testing when the raw mill is off-line and
when the raw mill is on-line to document compliance with the emission
standards and must establish separate operating parameters for each
mode of operation. These kilns must document in the operating record
each time they change from one mode of operation to the alternate mode.
They must also begin calculating new rolling averages for operating
parameter limits and comply with the operating parameter limits for
that mode of operation, after they officially switch modes of
operation. If there is a transition period associated with changing
modes of operation, the kiln operator has the discretion to determine
when, during this transition, the kiln has officially switched to the
alternate mode of operation and when it must begin complying with the
operating parameter limits for that alternate mode of operation. See
63.1204(d)(1).
Preheater/precalciner kilns with dual stacks that also have in-line
raw mills do not have to conduct dioxin/furan testing in the bypass
stack to demonstrate compliance with the standard when the raw mill is
off-line. We have concluded that dioxin/furan emissions in the bypass
stack are not dependent on the raw mill operating status because
dioxin/furan emissions are primarily dependent on temperature control.
A kiln may assume that when the raw mill is off-line, the dioxin/furan
emissions in the bypass stack are identical to the dioxin/furan
emissions when the raw mill is on-line and may comply with the bypass
stack dioxin/furan raw mill on-line operating parameters for both modes
of operation. See Sec. 63.1204(d)(1).
F. Is Emission Averaging Allowable for Cement Kilns with Dual Stacks
and In-line Raw Mills?
In the April 1996 NPRM, we did not subdivide cement kilns by
process type when setting emission standards (see 61 FR at 17372-
17373). As a result, we received many comments from the cement kiln
industry indicating that preheater/precalciner cement kilns with dual
stacks and cement kilns with in-line raw mills have unique design and
operating procedures that necessitate the use of emission averaging
when demonstrating compliance with the emission standards. We addressed
these comments in the May 1997 NODA by discussing an allowance for
emission averaging (for all standards except for hydrocarbon/carbon
monoxide) at preheater/precalciner cement kilns with dual stacks when
demonstrating compliance with the emission standards (see 62 FR at
24240). We also discussed allowing cement kilns with in-line raw mills
to demonstrate compliance with the emission standards on a time-
weighted average basis to account for different emission
characteristics when the raw mill is active as opposed to when it is
inactive. In light of the favorable comments received, and the lack of
significant concerns to the contrary, we adopt these emission averaging
provisions in today's rule.
1. What Are the Emission Averaging Provisions for Cement Kilns with In-
line Raw Mills?
See Sec. 63.1204(d).
As explained in the May 1997 NODA, emissions of hazardous air
pollutants can be different when the raw mill is active versus periods
of time when the mill is out of service. We received many comments on
this issue, all in favor of an emissions averaging approach to
accommodate these different modes of operation. As a result, we adopt a
provision that allows cement kilns that operate in-line raw mills to
average their emissions on a time-weighted basis to show compliance
with the metal and chlorine emission standards.
Emission averaging for in line raw mills will not be allowed when
they demonstrate compliance with the hydrocarbon/carbon monoxide
standard
[[Page 52970]]
because hydrocarbon and carbon monoxide are monitored continually and
serve as a continuous indicator of combustion efficiency. No commenter
states that emission averaging is needed for hydrocarbon/carbon
monoxide. Emission averaging for particulate matter will not be allowed
because this standard is based on the New Source Performance Standards
found in Sec. 60.60 subpart F. We interpret these standards to apply
regardless if the raw mill is on or off. (Note that this is consistent
with the proposed Nonhazardous Waste Portland Cement Kiln Rule. See 56
FR 14188). In addition, emission averaging for dioxin/furan will not be
allowed because cement kilns with in-line raw mills are expected to
control temperature during both modes of operation to comply with the
standard. No commenter stated that emission averaging was needed for
dioxin/furan.
a. What Is the Averaging Methodology? In the May 1997 NODA, we did
not specify an averaging methodology. As a result, commenters suggested
that the following equation would adequately calculate the time-
weighted average concentration of a regulated constituent when
considering the length of time the in-line raw mill is on-line and off-
line:
[GRAPHIC] [TIFF OMITTED] TR30SE99.028
Where:
Ctotal = time-weighted average concentration of a regulated
constituent considering both raw mill on time and off time.
Cmill-off = average performance test concentration of
regulated constituent with the raw mill off-line.
Cmill-on = average performance test concentration of
regulated constituent with the raw mill on-line.
Tmill-off = time when kiln gases are not routed through the
raw mill.
Tmill-on = time when kiln gases are routed through the raw
mill.
We agree that this equation properly calculates the time-weighted
average concentration of the regulated constituent when considering
both raw mill operation and raw mill down time and are adopting it in
today's rule.
b. What Is Required During Emission Testing? As discussed, sources
that use this emission averaging provision must conduct performance
testing for both modes of operation (with the raw mill both on-line and
off-line), demonstrating appropriate operating parameters during both
test conditions. One commenter suggests that the Agency allow sources
to demonstrate both raw mill on-line and off-line operations within the
same test runs. This would allow a test under one condition instead of
two and would give more flexibility by ensuring identical operating
parameters for raw mill on-line operations as opposed to off-line
operations. This also could theoretically result in fewer automatic
waste feed cutoffs when transitioning from one mode of operation to
another. Although this approach may have some benefit, we conclude that
it is necessary to demonstrate, through separate emission testing, the
comparison of emissions when operating with the raw mill on-line as
opposed to the raw mill off-line. The separate emission testing is
necessary to demonstrate whether emissions are higher or lower when the
raw mill is not active to assure compliance with the emission standards
on a time-weighed basis.276
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\276\ The Agency does not have, nor did commenters submit,
sufficient data to determine whether emissions will be higher or
lower when the raw mill is inactive.
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c. How Is Compliance Demonstrated? In the May 1997 NODA, we did not
discuss specific compliance provisions of an emission averaging
approach. After careful consideration, however, we determine that to
use this emission averaging provision, you must document and
demonstrate compliance with the emission standards on an annual basis
by using the above equation. Shorter averaging times were considered,
but were not chosen since it may be difficult for a kiln with an in-
line raw mill to comply with a short averaging period if the raw mill
must be off-line for an extended period of time. Therefore, you must
annually document in your operating record that compliance with the
emission standard was demonstrated for the previous year's operation by
calculating your estimated annual emissions with the above equation.
The one-year block average begins on the day you submit your NOC. You
must include all hazardous waste operations in that one year block
period, and you also must include all nonhazardous waste operations
that you elect to comply with hazardous waste MACT standards, when
demonstrating annual compliance.277
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\277\ Today's rulemaking allows a hazardous waste source, when
not burning hazardous waste, to either comply with the hazardous
waste cement kiln MACT standards or the non hazardous waste cement
kiln standards (see Part Five, Section I).
---------------------------------------------------------------------------
d. What Notification Is Required? Again, in the May 1997 NODA, we
did not discuss specific notification requirements. After careful
consideration, we determined that if you use this emission averaging
provision, you must notify the Administrator of your intent to do so in
your performance test workplan. Several commenters favor allowing time-
weighted emissions averaging, so long as historical data are submitted
to justify allowable time weighting factors (explained below). We agree
with these comments and require that you submit historical raw mill
operation data in your performance test workplan. These data should be
used to estimate the future down-time the raw mill will experience. You
must document in your performance test workplan that estimated
emissions and estimated raw mill down-time will not result in an
exceedance of the emission standard on an annual basis. You also must
document in your NOC that the emission standard will not be exceeded
based on the documented emissions from the compliance test and
predicted raw mill down-time.
2. What Emission Averaging Is Allowed for Preheater or Preheater-
Precalciner Kilns with Dual Stacks? (See Sec. 63.1204(e).)
As explained in the May 1997 NODA, and in an earlier
section of this preamble (see Part Four, Section V.II.B), emissions of
hazardous air pollutants can be different in a preheater or preheater-
precalciner cement kiln's main stack as opposed to the bypass stack. We
received many comments on this issue, all in favor of the emissions
averaging approach discussed in the NODA to accommodate the different
emission characteristics in these stacks. Therefore, we today finalize
a provision to allow preheater or preheater-precalciner cement kilns
with dual stacks to average emissions on a flow-weighted basis to
demonstrate compliance with chlorine and metal emission standards.
Emission averaging to demonstrate compliance with the hydrocarbon/
carbon monoxide standard is not
[[Page 52971]]
needed at preheater and preheater-precalciner cement kilns with dual
stacks since today's rule requires these kilns to monitor hydrocarbon
or carbon monoxide in the bypass stack only.278 Emission
averaging for particulate matter is no longer needed since the format
of the standard (0.15 kg/Mg dry feed) implicitly requires the kiln to
consider mass emissions from both stacks to demonstrate compliance with
the emission standard. In addition, emission averaging for dioxin/furan
will not be allowed because cement kilns with dual stacks are expected
to control temperature in both air pollution control systems to comply
with the standard. No commenter stated that emission averaging was
needed for dioxin/furan.
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\278\ New kilns at greenfield locations must also comply with a
main stack hydrocarbon standards. For these sources, emission
averaging for hydrocarbons would not appropriate because the purpose
of the main stack hydrocarbon standard is to control organic
hazardous air pollutants that originate from the raw material.
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a. What Is the Average Methodology? In the May 1997 NODA, we did
not specify an averaging methodology. However, commenters suggested
that the following is an appropriate equation to calculate the flow-
weighted average concentration of a regulated constituent when
considering emissions from both stacks:
[GRAPHIC] [TIFF OMITTED] TR30SE99.029
Where:
Ctot = flow-weighted average concentration of the regulated
constituent
Cmain = average performance test concentration demonstrated
in the main stack
Cbypass = average performance test concentration
demonstrated in the bypass stack
Qmain = volumetric flowrate of main stack effluent gas
Qbypass = volumetric flowrate of bypass effluent gas
We agree that this equation properly calculates the flow-weighted
average concentration of the regulated constituent when considering
emissions from both stacks and it is adopted in today's rule.
b. What Emissions Testing and Compliance Demonstrations Are
Necessary? To use this emission averaging provision, you must
simultaneously conduct performance testing in both stacks during your
comprehensive performance test to compare emission levels of the
regulated constituents (as proposed). These emission data must be used
as inputs to the above equation to demonstrate compliance with the
emission standard.
You must develop operating parameter limits, and incorporate these
limits into your NOC, that ensures your emission concentrations, as
calculated with the above equation, do not exceed the emission
standards on a twelve-hour rolling average basis. These operating
parameters should limit the ratio of the bypass stack flowrate and
combined bypass and main stack flowrate such that the emission standard
is complied with on a twelve-hour rolling average basis. Whereas this
was not proposed, we conclude that this provision is necessary to
assure compliance with the standards since the ratio of stack gas
flowrate and bypass stack flowrate could deviate from the levels
demonstrated during the performance test.
c. What Notification Is Required? In the May 1997 NODA, we did not
discuss specific notification requirements. After careful
consideration, however, we determine that to use this emission
averaging provision, you must notify the Administrator of your intent
to do so in your performance test workplan. The performance test
workplan must include, at a minimum, information that describes your
proposed operating limits. You must document your use of this emission
averaging provision in your NOC and document the results of your
emissions averaging analysis after estimating the flow weighted average
emissions with the above equation. You must also incorporate into the
NOC the operating limits that ensures compliance with emission
standards on a twelve-hour rolling average basis.
G. What Are the Special Regulatory Provisions for Cement Kilns and
Lightweight Aggregate Kilns that Feed Hazardous Waste at a Location
Other Than the End Where Products Are Normally Discharged and Where
Fuels Are Normally Fired? (Sec. 63.1206(b)(12) and (b)(8)(ii))
As discussed in Part Four, Section IV.B., the Agency is allowing
you to comply with either a carbon monoxide or hydrocarbon standard.
However, we have concluded that this option to comply with either
standard should not apply if you operate a cement kiln or lightweight
aggregate kiln and feed hazardous waste at a location other than the
end where products are normally discharged and where fuels are normally
fired these other locations include, at the mid kiln or the cold, upper
end of the kiln. Consistent with the Boilers and Industrial Furnace
regulations (see Sec. 266.104(d)), we are today requiring you to comply
with the hydrocarbon standard, and are not giving you the option to
comply with the carbon monoxide standard, if you feed hazardous waste
in this manner. This is because we are concerned that hazardous waste
could be fired into a location such that nonmetal compounds in the
waste may be merely evaporated or thermally cracked to form pyrolysis
byproducts rather than be completely combusted.279 If this
occurs, there is the potential that little carbon monoxide will be
generated even though significant hydrocarbons are being emitted.
Carbon monoxide monitoring would thus not ensure that organic hazardous
air pollutant emissions are being properly controlled. We do not
anticipate this requirement to be overly burdensome, since it is a
current requirement of the Boilers and Industrial Furnace regulation.
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\279\ See Final Rule, Burning of Hazardous Waste in Boilers and
Industrial Furances, February 21, 1991, 56 FR at 7158.
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We have also concluded that it would not be appropriate for you to
comply with the hydrocarbon standard in the bypass duct if you operate
a cement kiln and feed hazardous waste into a location downstream of
your bypass sampling location relative to flue gas flow direction. Such
operation would result in hazardous waste combustion that would not be
monitored by a hydrocarbon monitor. Today's rulemaking thus requires
you to comply with the main stack hydrocarbon standard of 20 ppmv if
you feed hazardous waste in this manner. This is also consistent with
the Boilers and Industrial Furnace regulations, which do not allow you
to monitor hydrocarbons in the bypass duct if you operate a short kiln
and if you feed hazardous waste in the preheater or precalciner (see
Sec. 266.104(f)(1)).
In addition to the above requirements, if you operate a cement kiln
or
[[Page 52972]]
lightweight aggregate kiln and feed hazardous waste at a location other
than the end where products are normally discharged and where fuels are
normally fired, you are also required to demonstrate compliance with
the destruction and removal efficiency standard every five years as
opposed to a one-time destruction and removal demonstration We require
you to do this because the unique design and operation of such a waste
firing system necessitates a compliance demonstration for this standard
every five years (see previous discussion in part Four, Section
IV.A.3.).
H. What is the Alternative Particulate Matter Standard for
Incinerators? See Sec. 63.1206(b)(15).
As discussed in Part Four, Section II.A.2, today's rule establishes
a particulate matter standard of 0.015 gr/dscf for incinerators as a
surrogate to control nonenumerated metal hazardous air pollutants
(i.e., antimony, cobalt, manganese, nickel, selenium). Of course,
particulate matter air pollution control devices also exert control on
other metals (except highly volatile species such as mercury),
including the enumerated metals. (The enumerated metal hazardous air
pollutants are those CAA metal hazardous air pollutants regulated
directly via individual emission standards in today's rule, i.e.,
mercury, semivolatile metals, low volatile metals). A number of
commenters, primarily incinerator operators, assert that a particulate
matter standard should not be used as a surrogate control for metals in
situations where the particulate matter does not contain any metal
hazardous air pollutants (i.e., situations when the waste does not
contain any metals, except perhaps mercury and the resulting ash
contains only relatively benign ash or soot). These commenters argue
that the cost associated with reducing particulate matter levels below
0.015 gr/dscf would be excessive and that some type of alternative
standard (reflecting superior metal feedrate control) be created.
After considering these comments and another type of particulate
matter control technology, we conclude that it is appropriate to offer
an alternative particulate matter standard of 0.03 gr/dscf for
incinerators that have de minimis levels of hazardous air pollutant
metals in their feedstreams, and we have adopted a petition process to
allow incinerators to seek this alternative standard. An alternative
particulate matter standard is within the scope of our overall preamble
discussions of the control of particulate matter and metal emissions,
the ways in which the Agency was considering feedrate as part of its
MACT analysis, our approaches to enumerated and non-enumerated CAA
hazardous air pollutant metals, and the presentation of options for
compliance testing when only de minimis levels of metals are present.
1. Why is this Alternative Particulate Matter Standard Appropriate
under MACT?
An alternative particulate matter floor level of 0.030 gr/dscf is
appropriate for an incinerator that can demonstrate it has de minimis
levels of CAA hazardous air pollutant metals (except mercury), as
defined below, in its feedstreams. As discussed in other portions of
this preamble and in our technical background documents for this
rulemaking, control of metals (other than mercury) is a function, in a
practical sense, of both the feedrate of those metals into the
combustion device as well as the design, operation, and maintenance of
a source's air pollution control devices for particulate matter. Given
the intertwined relationship between these two factors, the Agency has
concluded that a particulate matter floor control level of 0.015 gr/
dscf is not warranted for sources using superior feedrate control (i.e.
beyond MACT) to reduce metal emissions, which in this case would be
shown by having non-detectable levels of metals in their feedstreams
(discussed in more detail below).280
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\280\ We do not require you to document that your feedstreams
have de minimis mercury levels to qualify for this alternative
standard because mercury is a volatile metal and is generally not
controlled with particulate matter control technologies.
---------------------------------------------------------------------------
We also conclude that the floor control for this alternative
standard is the use of a venturi scrubber or the use of the same, but
less sophisticated, particulate matter control technologies that were
established for the 0.015 gr/dscf standard.281 These floor
technologies, including venturi scrubbers, were the basis of our
particulate matter floor standard of 0.029 gr/dscf which was published
for comment in the May 1997 NODA. See 62 FR at 24221. Although we have
since determined that 0.015 gr/dscf is a technically achievable and
appropriate MACT floor control level for incinerators based on a suite
of technologies that does not include venturi scrubbers, we conclude
that an alternative floor level of 0.030 gr/dscf that includes venturi
scrubbers in the floor is appropriate for sources using superior metal
feedrate control. Put another way, we view the average of the 12
percent best performing incinerators as including incinerators with
venturi scrubbers when the incinerator is exercising beyond-MACT feed
control of hazardous air pollutant metals.282 We also note
that the final rule for medical waste incinerators establishes a
particulate matter standard of 0.030 gr/dscf for medium sized existing
sources and small new sources that is based on medium efficiency
venturi scrubbers. See 62 FR at 48348. The alternative floor level of
0.030 gr/dscf that is adopted in this final rulemaking is appropriate
when we include venturi scrubbers as an alternative floor control
technology when superior feed rate control is being
employed.283
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\281\ As discussed in Part Four, Section VI.C.4.a, particulate
matter floor control for hazardous waste incinerators is defined as
the use of either fabric filters, electrostatic precipitators (dry
or wet), or ionizing wet scrubbers (sometimes in combination with
venturi, packed bed, or spray tower scrubbers) that achieve
particulate matter emission levels of 0.015 gr/dscf or less.
\282\ See Final Technical Support Document, Volume 3, Chapter
Four, July, 1999, for further discussion.
\283\ The cement kilns and lightweight aggregate kilns that are
also covered by today's final rule have feedrates of metals far
above any de minimis threshold. See Final Technical Support
Document, Volume 3, Chapter Four, July, 1999, for further
discussion. Therefore, in light of the commenters requesting
alternative standards and in light of the feedstream levels of
metals going into the kilns, we have elected to offer an alternative
particulate matter standard only to incinerators.
---------------------------------------------------------------------------
Particulate matter control below 0.030 gr/dscf is still necessary
to control metal emissions at sources with de minimis levels of
hazardous air pollutant metals in their feedstreams for several
reasons. Even if an incinerator obtains non-detect analytical results
for one or more metals in its feedstream, this does not conclusively
prove that metals are absent. Rather, all that such laboratory results
mean is that the metals are not contained in the feedstream above the
detection limit used in the analysis. This detection limit may be low
but it can also be fairly high depending on the waste matrix. As
previously discussed in Part Five, Section X.C.1, commenters have
indicated that feedstream metal detection limits are highly dependent
on the feedstream matrix.
Given that our prerequisite for the alternative standard is that de
minimis levels of metals are present, we must take into account this
phenomenon of matrix-dependent detection limits. We are unwilling
simply to allow facilities upon a showing of non-detectable levels of
metals to avoid particulate matter controls entirely, especially given
the complementary controls in practice provided by both feedrate
control and
[[Page 52973]]
particulate matter air pollution control devices. On the other hand, it
would be overly narrow to give essentially no credit for superior
feedrate control (shown by non-detectable levels of metals) by
requiring these incinerators to meet 0.015 gr/dscf. It appears,
therefore, to be an appropriate balance to allow facilities with non-
detectable levels of metals (other than mercury) to meet a standard of
0.030 gr/dscf. This will assure control reflecting performance of the
best performing plants that use superior (i.e., beyond MACT) feedrate
control, especially in the event that detection limits for a particular
waste matrix are unusually high. Because we are moving to a Performance
Based Measurement System (PBMS) we cannot rely upon previously approved
EPA standard methods as a means to predict detection levels in various
matrices. Therefore, we are retaining a particulate matter standard
0.030 gr/dscf to offset the potential for high detection limits.
2. How Do I Demonstrate Eligibility for the Alternative Standard?
Although we adopt a particulate matter standard as a surrogate to
control nonenumerated metal hazardous air pollutants, particulate
matter control is an integral part of the semivolatile and low volatile
metal emission standards as well, as discussed above. See Part Four,
Section II.A.1, for further discussion. We therefore conclude that you
must document that not only the nonenumerated metals meet the de
minimis criteria explained below, but that the semivolatile and low
volatile metals do as well. This provides assurance that superior
feedrate control is being achieved for all hazardous air pollutant
metals, which in turn allows us to provide you with the opportunity to
use the alternative particulate matter standard.
To demonstrate eligibility, you must document that you meet two
qualification requirements. First, you must document that your
feedstreams do not contain detectable levels of CAA hazardous air
pollutant metals, apart from mercury (i.e., antimony, cobalt,
manganese, nickel, selenium, lead, cadmium, chromium, arsenic and
beryllium). This requirement is necessary to ensure that you have de
minimis levels of metals in your feedstreams, and assures us that you
are using superior feedrate control. You must conduct feedstream
analyses at least annually to document that your feedstreams do not
contain detectable levels of these metals. Permitting officials may, on
a site-specific basis, require more frequent feedstream analyses to
better ensure that you comply with this eligibility requirement.
Second, you must document that your calculated uncontrolled metal
emissions, i.e., no system removal efficiency, are below the numerical
semivolatile and low volatile metal emission standards. When
calculating these uncontrolled emissions, you must assume metals are
present at one-half the detection limit and are categorized into their
appropriate volatility grouping for purposes of this requirement. The
one-half detection limit assumption provides a relatively, but not
overly, conservative way assuring that de minimis determinations are
not given to sources with very high detection limits.
For example, the combined uncontrolled emissions for lead, cadmium
and selenium, when assuming these metals are present at one-half the
detection limit, must be below 240 g/dscm. The combined
uncontrolled emissions for antimony, cobalt, manganese, nickel,
chromium, arsenic and beryllium, when assuming these metals are present
at one-half the detection limit, must be below 97 g/dscm. We
require this second eligibility requirement because (1) it ensures you
have de minimis levels of metals in your feedstreams even though metals
can be present at levels below the detection limit, and (2) it
encourages you to obtain reasonable detection limits.
3. What Is the Process for the Alternative Standard Petition?
If you are seeking this alternative particulate matter standard,
you must submit a petition request to the Administrator, or authorized
regulatory Agency, that includes the documentation discussed above. You
will not be allowed to operate under this alternative standard until
the Administrator determines that you meet the above qualification
requirements. Although we are not requiring that you include this
petition as part of the comprehensive performance test workplan, we
strongly recommend that you do so. This approach has several
advantages: (1) It will clarify which PM standard you are complying
with as of your documentation of compliance, and avoid potential
confusion about your state of compliance; (2) it will help ensure that
the planned performance tests cover all of the relevant parameters and
standards and will facilitate interpretation of performance test
results; (3) it will help avoid costs of having to conduct a separate
performance test to show compliance with the alternative standard,
which would include re-testing and re-establishment of many of the same
parameters as would be covered in the initial comprehensive performance
test; and (4) it will help maximize the time that the regulatory agency
needs to evaluate your demonstration of the prerequisite, non-detect
levels of metals in your feed, including the time needed for you to
respond to any additional information that may be requested by the
agency. Agency approval of a comprehensive performance test workplan
that also includes this petition request will be deemed as approval for
you to operate pursuant to this alternative standard. In our
implementation of today's final rule, we will address as appropriate
various considerations related to processing these petitions, including
the timing of the submittal, review and approval. We fully expect that
Agency permit officials will act expeditiously on these petitions so
that both the source and the reviewing official know what particulate
matter level the comprehensive performance test must show is being
achieved.
XI. What Are the Permitting Requirements for Sources Subject to this
Rule?
As indicated in Part One, we intend the requirements of this rule
to meet our obligations for hazardous waste combustor air emission
standards under two environmental statutes, the Clean Air Act and the
Resource Conservation and Recovery Act. The overlapping air emission
requirements of these two statutes have historically resulted in some
duplication of effort. In developing a permitting scheme that
accommodates the requirements of both statutes, with regard to the new
air emissions limitations and standards being promulgated in this rule,
our goal is to avoid any such duplication to the extent possible. This
goal is consistent with the RCRA statutory directive of section
1006(b)(1) to ``integrate all provisions of (RCRA) for purposes of
administration and enforcement and (* * *) avoid duplication, to the
maximum extent practicable, with the appropriate provisions of the
Clean Air Act.'' 284 It also is consistent with our
objectives to streamline requirements and follow principles that
promote ``good government.''
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\284\ See also CAA section 112(n)(7) (requirements of section
112 should be consistent with those of RCRA Subtitle C to the
maximum extent practicable).
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[[Page 52974]]
A. What Is the Approach to Permitting in this Rule?
1. In General What Was Proposed and What Was Commenters' Reaction?
In the April 1996 NPRM, we proposed placing the MACT air emissions
standards in the CAA regulations at 40 CFR part 63 and proposed to
reference the standards in the RCRA regulations at 40 CFR parts 264 and
266. (see 61 FR 17451, April 19, 1996). At that time, we believed that
placing the standards in both the CAA and RCRA regulations would
provide maximum flexibility to regulatory authorities at the Regional,
State, or local levels to coordinate permitting and enforcement
activities in the manner most appropriate for their individual
circumstances.285 We also believed that this approach would
alleviate the potential for duplicative requirements across permitting
programs.
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\285\ When referring to permitting under the CAA, we mean
operating permits under title V of the CAA. The regulations
governing state and federal title V permit programs are codified in
40 CFR parts 70 and 71, respectively.
---------------------------------------------------------------------------
In addition, we presented two examples of ways for permitting
hazardous waste combustors subject to the new MACT standards. These
examples reflected, in part, the proposed approach of incorporating the
new MACT standards into both RCRA and CAA implementing
regulations.286 (See 61 FR 17451, April 19, 1996.) In the
first example, the two permitting programs would work together to issue
one permit, under joint CAA and RCRA authority, that would meet all the
requirements of both programs. In the second example, the two
permitting programs would coordinate their efforts with each program
issuing a separate permit; the items common to both (e.g., the air
emissions standards) would be included in one permit and incorporated
by reference into the other permit.
---------------------------------------------------------------------------
\286\ The possibility of issuing only one EPA permit under
either CAA or RCRA authority, and the ensuing legal barriers
rendering that approach infeasible, also were discussed in the
preamble for the proposed rule (61 FR 17451, April 19, 1996).
---------------------------------------------------------------------------
Comments on the April 1996 NPRM expressed widespread support for
providing flexibility for regulatory agencies to implement common sense
permitting schemes that fit their organization and resources. However,
commenters disagreed as to which approach would best provide such
flexibility. A few commenters thought that the April 1996 NPRM
approach, placing the standards in both CAA and RCRA regulations, would
both provide flexibility to choose which program would issue permits
and therefore avoid duplication.
On the other hand, we received several comments challenging our
assumption that placement of the standards in both CAA and RCRA
regulations would optimize flexibility for regulatory agencies. These
commenters believed that the regulatory agencies would be, in fact,
more limited. They noted that both the RCRA and CAA programs would be
responsible for incorporating the standards, to some extent, into their
permits, even if just by referencing the other. Commenters also were
concerned with the potential for conflicting conditions between the two
permits, particularly with regard to testing, monitoring, and
certification requirements. In addition, they felt that the conditions
common to both permits might be subject to separate decision-making
processes. For example, they might potentially be subject to two
different administrative or judicial appeals procedures and two permit
modification procedures. If this happened, the Agency would not achieve
its stated objective of avoiding duplication between the two programs.
Additionally, our example pointing to close coordination between
programs to avoid duplication was countered by commenters examples
where such coordination has not occurred, either due to logistical
problems within regulatory agencies or to differences in administrative
processes between the two programs.
Commenters also expressed concern about the potential for
enforcement of the same requirement under two different statutes that
they believed the proposed approach would create. Since the
requirements would have to be incorporated into both RCRA permits and
CAA title V permits, sources would have to comply with both. Although
we stated in the proposal that we did not expect to take enforcement
action under both permits (see 62 FR 17452), commenters noted that this
would not restrain State or local authorities from initiating dual
enforcement actions. In addition, commenters pointed out that they
would be vulnerable to citizen suits under both statutes.
The majority of the commenters voiced a desire for the Agency to
avoid duplicate requirements or redundant processes. We received
several suggestions for alternative approaches, which can be grouped in
three ways: (1) Requiring regulatory agencies to develop a separate
permitting program to cover elements common to both CAA and RCRA (i.e.,
air emissions and related operating requirements) while maintaining
separate permits for the other elements; (2) Developing a single multi-
media permit to cover all RCRA and CAA requirements applicable to
hazardous waste combustors; and (3) placing the standards only in CAA
regulations and incorporation only into the title V permits.
The first alternative, i.e., requiring a separate permitting
program for air emissions and related parameters, is a very different
approach that would likely require the development of more new
regulations. However, duplication may be avoided without promulgation
of an ``independent'' permitting scheme just for the elements common to
both RCRA and CAA programs. Other alternatives would not involve the
time and effort needed to craft and adopt a new regulatory scheme, such
as that suggested.
We believe that the second alternative, pursuing multi-media
permits, had some merit. As commenters pointed out, the Agency's
Permits Improvement Team expressed support for multimedia permits in
its ``Concept Paper.'' The Permits Improvement Team also acknowledged,
however, that true multimedia permits have been difficult to develop.
We still support multimedia permitting, and this rule does not preclude
this approach. Nevertheless, we do not believe that, at this point, we
can rely on multimedia permitting as an overall approach to
implementing this rule. Some States have successfully piloted multi-
media permitting or implemented ``one-stop'' permits that address both
RCRA and CAA requirements. We encourage States to continue these
efforts and to apply them to hazardous waste combustor permitting to
the extent possible. Even for States that do not currently pursue
multimedia or one-stop permits, this rule presents unique opportunities
to start moving in that direction.
The third alternative had a couple of variations. The
straightforward version was simply to place the MACT air emission
standards in the CAA regulations, incorporate them into title V
permits, and continue to issue RCRA permits for other RCRA-regulated
aspects of the combustion unit, as well as of the rest of the facility
(e.g., corrective action, general facility standards, other combustor-
specific concerns such as materials handling, risk-based emissions
limits and operating requirements, as appropriate, and other hazardous
waste management units). A variation of this was to develop a RCRA
permit-by-rule provision to defer to title V permits. The
straightforward approach was favored by the majority of the commenters.
Some offered, as further support for this
[[Page 52975]]
position, a reference to the recommendation put forth by the Permit
Improvement Team's Alternatives to Individual Permits Task Force that
called for permitting air emissions from hazardous waste combustors
under the CAA. The variation of developing a RCRA permit-by-rule
provision is not as responsive to commenters' concerns because, among
other things, that approach would not avoid the potential for dual
enforcement. Although the permit-by-rule has the effect of deferring to
the title V permit, the facility is still considered to have a RCRA
permit for the combustor's air emissions.
2. What Permitting Approach Is Adopted in Today's Rule?
We found the arguments for the straightforward approach (i.e.,
placing the standards only in the CAA regulations and relying on the
title V permitting program) persuasive. Based on the comments we
received, and our subsequent analysis, we narrowed our options for how
to permit hazardous waste combustors subject to the new MACT standards
and elaborated on our preferred approach in the May 1997 NODA (see 62
FR 24249). In the NODA, we described an approach to place the MACT
emissions standards only in the CAA regulations at 40 CFR part 63
Subpart EEE, and rely on implementation through the air program,
including operating permit programs developed under title V. Under this
approach, which we are adopting in today's final rule, MACT air
emissions and related operating requirements are to be included in
title V permits; RCRA permits will continue to be required for all
other aspects of the combustion unit and the facility that are governed
by RCRA (e.g., corrective action, general facility standards, other
combustor-specific concerns such as materials handling, risk-based
emissions limits and operating requirements, as appropriate, and other
hazardous waste management units).
Placement of the emissions standards solely in part 63 appears to
be the most feasible way to avoid duplicative permitting requirements.
We agree with the commenters' views that placement of the standards in
both RCRA and CAA regulations would require both permits to address air
emissions. Permitting authorities would not be able to choose which
program would be responsible for implementing the requirements. Placing
the standards in both sets of regulations would obligate both programs
to address the standards in permits issued under their respective
authorities. Simply put, permitting authorities would not be free to
incorporate the new standards into either CAA title V permits or RCRA
permits; rather, they would need to incorporate the new standards, to
some degree, into both permits.287 Having determined that
placement of the standards in both sets of regulations is not
desirable, we revisited the question of whether one program could defer
to the other. The CAA does not provide authority to defer to other
environmental statutes,288 so we could not place the MACT
standards solely in RCRA regulations, which would have consequently
allowed them to be incorporated only into a RCRA permit. On the other
hand, RCRA does provide authority to forego RCRA emissions standards in
favor of MACT standards imposed under the CAA. As stated above in Part
One, Section I, under the authority of RCRA section 3004(a), it is
appropriate to eliminate these RCRA standards because they would only
be duplicative and so are no longer necessary to protect human health
and the environment. Also as discussed there, RCRA section 1006(b)
provides further authority for the Administrator to eliminate the
existing RCRA air emissions standards in order to avoid duplication
with the new MACT standards. Thus, we use our authority to defer RCRA
controls on the air emissions to the part 63 MACT standards, which
ultimately are incorporated into title V permits issued under the CAA.
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\287\ As discussed earlier, states may be able to develop
combined permits that address both RCRA and CAA requirements. Such
permits would have to cite the appropriate authority (CAA or RCRA)
for each condition, and have to be signed by the appropriate
officials of each program. Permit conditions would continue to be
enforced under their respective authorities as well.
\288\ Although CAA section 112(n)(7) is directed at harmonizing
requirements with RCRA, it does not provide a jurisdictional basis
for deferral (i.e., nonpromulgation of mandated section 112(d) MACT
standards in light of the existence of RCRA standards).
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The majority of the comments received following publication of the
May 1997 NODA supported our preferred approach to permitting the
hazardous waste combustors. Several commenters expressed appreciation
for this effort, and concluded that our approach would avoid
duplication and have the RCRA and title V permits work to complement
each other rather than potentially contradict each other. Although
sources will still have two permits, the scope and subject matter of
each will be distinguishable. The title V permit will focus on the
operation of the combustion unit (e.g., air emissions and related
parameters) while the RCRA permit will continue to focus on basic
hazardous waste management at the facility (e.g., general facility
standards, corrective action, other units, and so on). The only time
there might be conditions in both RCRA and title V permits that address
the same hazardous waste combustor operating requirements and limits is
when there is a need to impose more stringent risk-based conditions,
e.g., under RCRA ``omnibus'' authority, in the RCRA permit. The RCRA
permitting authority would add terms and conditions based on the
omnibus clause only if it found, at a specific facility, that the MACT
standards were not sufficient to protect human health or the
environment. This issue is discussed in greater detail in Part III,
Section IV (RCRA Decision Process). In those limited cases, sources and
permitting agencies may agree to identify the RCRA limit in the title V
permit. Since one goal of the title V program is to clarify a source's
compliance obligations, it will be beneficial, and convenient, to
acknowledge the existence of more stringent limits or operating
conditions derived from RCRA authority for the source in the title V
permit, even though the requirements would not reflect CAA
requirements. We strongly encourage Regional, State, and local
permitting authorities to take advantage of this beneficial option.
Some commenters continued to maintain that flexibility to choose
which program would permit air emissions would only be provided if we
were to promulgate the standards in both CAA and RCRA regulations. They
reiterated the position they had taken in their comments on the initial
proposal that this approach would not result in duplication across the
programs; they discounted concerns over duplicative requirements or
dual enforcement scenarios by saying that it was basically not in a
permitting authority's best interests to issue duplicate permits. We
found the contrary, that placement of the standards in both sets of
regulations does not provide flexibility for a regulatory agency to
choose one permit program or another. Such an approach would obligate
both permits to cover air emissions and related operating requirements.
This result does not achieve our or the commenters' objective of
avoiding duplication across programs. Although the actual burden on
permit writers may not be significant if, for example, the title V
permit were to just cross-reference the appropriate sections of the
RCRA permit, the requirements would still be enforceable under both
vehicles, and would go through dual administrative processes. As
mentioned above, EPA would like to
[[Page 52976]]
avoid this type of dual enforcement and dual process scenario in
implementing the new standards.
3. What Considerations Were Made for Ease of Implementation?
Our approach in the final rule does not limit the options available
to state permitting authorities for implementing the new standards. The
primary concern about which program (RCRA or CAA) assumes lead
responsibility for administering air emissions requirements appears to
revolve around resource issues. The RCRA program has been the lead
program for permitting hazardous waste combustors for many years,
consequently, RCRA program staff have developed a great deal of
expertise in this area. They are familiar with source owners and
operators, the combustion units, and special considerations associated
with permitting hazardous waste combustion activities. Some commenters
are concerned that by deferring regulation of air emissions standards
to the CAA, that expertise will no longer be available. They express
doubt about the ability of air toxics implementation programs and title
V programs to take on these sources, given the complexity of hazardous
waste combustor operations and the volume of title V permits that need
to be issued over the next several years.289
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\289\ Title V permits are required for many more sources than
those subject to the HWC MACT standards. Currently, there are
approximately 20,000 sources that are subject to title V; there are
only about HWCs subject to today's rule.
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In response to these comments, we note that many State Air programs
currently play key roles in permitting hazardous waste combustors under
RCRA. Furthermore, States may find that much of the expertise used to
regulate other air sources is directly applicable to regulating the
hazardous waste combustor sources subject to the new MACT standards,
and that the resources in their air programs are sufficient to handle
these additional sources. If, however, a State shares commenters'
concerns that its air program, as it currently exists, may not be able
to take on these sources, the State may continue using the resources
and expertise of its RCRA program even though the new standards are
being promulgated as part of the CAA regulations.
In the May 1997 NODA, we discussed the flexibility afforded to
States by codifying the standards under only one statute (see 62 FR
24246). Two potential options were described in the NODA for how this
might be achieved: (1) A State could simply have its RCRA staff
implement the hazardous waste combustor MACT standards; or (2) a State
could formally incorporate the standards into its State RCRA program.
In response to the NODA, some State environmental agencies commented
that, as a matter of State law, they would not be able to incorporate
the new standards into their authorized hazardous waste programs unless
they are included in federal RCRA regulations. We acknowledge,
therefore, that some States may not be able to pursue the second
option. In any case, we recommend against this option because, as
discussed below, it would perpetuate having duplication between two
permits. The first option would, however, still be feasible. For
example, the States could explore the flexibility provided through
Performance Partnership Agreements 290 if they would like to
have their RCRA program staff continue their work with the hazardous
waste combustors.
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\290\ Within negotiated agreements, there is flexibility in
Performance Partnership Grants to strategically move funds, and
flexibility in Performance Partnership Agreements found in the
National Environmental Performance Partnership System to
strategically integrate programs.
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If a State chooses to use either of the above options to continue
applying RCRA expertise to hazardous waste combustors, we anticipate
that RCRA program staff would be responsible for many of the
implementation activities, such as reviewing documents submitted by the
source (e.g., the Notice of Intent to Comply, the progress report, and
the performance test plan), and working with the source to resolve any
differences (e.g., on anticipated operating requirements or on results
of comprehensive performance tests).
Where the process issues would start to diverge between the two
options is at the actual permitting stage. Under the first option (RCRA
staff implementing CAA regulations), the standards would be
incorporated only into title V permits. Title V permits cover a wide
range of applicable requirements under the CAA; the hazardous waste
combustor MACT standards are likely to be just one piece.291
We believe that the RCRA permit writer would draft the hazardous waste
combustor portion of the title V permit, and would coordinate with the
title V permit writer in the CAA program who has responsibility for the
source's overall permit to ensure that the hazardous waste combustor
portion is properly incorporated. In short, the RCRA permit writer
would simply be developing a component of a title V permit instead of
developing a component of a RCRA permit. State permitting authorities
that wish to continue using their RCRA expertise will undoubtedly
explore this approach.
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\291\ If the HWC MACT standards are the only applicable CAA
requirements, however, then there would be no other components of a
title V permit for the source.
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If a State pursues the second option of incorporating the new
hazardous waste combustor MACT standards into its State RCRA program,
there may still be a need to incorporate the standards into both title
V and RCRA permits. The CAA does not provide authority to defer title V
permitting to other environmental programs. Thus, the source would
still be subject to title V requirements (i.e., a RCRA permit could not
``replace'' a title V permit). Furthermore, an EPA Region or a State
who chooses to obtain authorization for the hazardous waste combustor
MACT standards under RCRA would also have to start implementing the new
standards under CAA authority (including title V permitting
requirements) even as the State begins efforts to incorporate the
standards into its State RCRA program.
Although close cooperation between the RCRA and title V permit
writers could minimize duplicative efforts in developing permits and
avoid conflicting conditions in the two permits (for example, by
putting the conditions in one permit and just referencing them in the
other), this approach still results in the potential for enforcement
and citizen suits under both permits. 292 As discussed
above, we intend to avoid duplicate permitting and enforcement
scenarios for hazardous waste combustor MACT standards; thus, we
strongly encourage States that choose to pursue this approach to
develop implementation schemes that minimize the potential for such
duplication to the extent practicable.
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\292\ Some States have successfully issued ``one-stop''
multimedia permits which include provisions from both the CAA and
RCRA programs in a single permit. However, it is EPA's understanding
that these permits cite both the RCRA and CAA authority; thus, the
potential for enforcement under both statutes still remains.
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B. What Is the Applicability of the Title V and RCRA Permitting
Requirements?
This section briefly summarizes the applicability of both title V
and RCRA permitting requirements under the permitting scheme discussed
in Section XI. A. above. It also discusses the relationship of this
permitting scheme to both the proposed revisions to combustion
permitting procedures from June 1994 and to the RCRA preapplication
meeting requirements. Our decision to subject hazardous waste
combustors that are considered area
[[Page 52977]]
sources under the CAA to title V permitting is discussed in a separate
section.
1. How Are the Title V Permitting Requirements Applicable?
We intend, by placing the new standards only in 40 CFR part 63 and
not cross-referencing them in RCRA regulations, to rely on existing air
programs to implement the new requirements, including operating permits
programs developed under title V. All hazardous waste combustors
subject to the MACT standards promulgated in this rule will thus be
subject to title V permitting requirements for air emissions and
related operating requirements (this includes hazardous waste
combustors that are considered area sources under the CAA, as discussed
in more detail below). In this rule, we are not amending any of the
existing air permitting procedures. The procedures of 40 CFR part 71
for federal operating permits, or a State title V program approved
under part 70, will remain applicable. Thus, all current CAA
requirements governing permit applications, permit content, permit
issuance, renewal, reopenings and revisions will apply to air emissions
from hazardous waste combustors pursuant to promulgation of the
hazardous waste combustor MACT standards.293
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\293\ Requirements of other CAA permitting programs, such as
construction permits, will continue to apply, as appropriate, to the
HWC's sources subject to today's rule.
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The public participation requirements for title V permits in parts
70 and 71, such as allowing an opportunity for public hearing and
public comments on draft permits, also apply (see 40 CFR 70.7(h) and
71.11). We are committed to enhancing public participation in all of
our programs. In 1996, we published a guidance manual on public
involvement in the RCRA program intended to improve cooperation and
communication among all participants in the RCRA permitting process
(RCRA Public Participation Manual, EPA530-R-96-007, September 1996).
Although the Manual is written in the context of the RCRA program, the
principles are common to all program areas. For example, the Manual
encourages early and meaningful involvement for communities and open
access to information. It also acknowledges the important role of
public participation in addressing environmental justice concerns.
Since these principles are applicable in all situations, we encourage
air programs and sources subject to the hazardous waste combustor MACT
standards to refer to the RCRA manual for additional guidance on
implementing effective public participation activities.
2. What Is the Relationship Between the Notification of Compliance and
the Title V Permit?
The hazardous waste combustor MACT standards promulgated in this
final rule include emissions limitations for several hazardous air
pollutants, as well as detailed compliance, testing, monitoring, and
notification requirements. Under these provisions, you not only
demonstrate compliance with the emissions limitations, but also
demonstrate that you have established operating requirements and
monitoring methods that ensure continuous compliance with those limits.
These demonstrations are made during a comprehensive performance test
and subsequently documented in an NOC.
We are requiring, in Sec. 63.1210(f), that you comply with the
general provisions governing the NOC codified in Sec. 63.9(h). Those
provisions specify that in addition to describing the air pollution
control equipment (or method) for each emission point for each
hazardous air pollutant, the NOC also must include information such as:
methods that were used to demonstrate compliance; performance test
results; and methods for determining continuous compliance (including
descriptions of monitoring and reporting requirements and test
methods). We also are requiring in Sec. 63.1207(j) that you comply with
the all of the operating requirements specified in the NOC upon
submittal to the Administrator.
Although these requirements are self-implementing, in that you must
comply in accordance with the time frames set forth in today's rule,
the requirements are ultimately implemented through title V operating
permits (see 40 CFR parts 70 and 71). Section 63.1206(c)(1) specifies
that: (1) You can only operate under the operating requirements
specified in the DOC or NOC (with some exceptions as laid out in the
regulations); (2) the DOC and NOC must contain operating requirements
including, but not limited to, those in Sec. 63.1206 (compliance with
the standards and general requirements) and Sec. 63.1209 (monitoring
requirements); (3) operating requirements in the NOC are applicable
requirements for the purposes of 40 CFR parts 70 and 71; and, (4)
operating requirements in the NOC must be incorporated into the title V
permit. In addition, because title V permits can only be issued if,
among other conditions, ``the conditions of the permit provide for
compliance with all applicable requirements'' (see Secs. 70.7(a)(1)(iv)
and 71.7(a)(1(iv)), parts 70 and 71 are clear that title V permits must
contain the operating requirements documented in the NOC.
As mentioned above, you must comply with all operating requirements
specified in the NOC as of the postmark date when the NOC is submitted
to the Administrator. Operating requirements documented in the NOC must
be included in your title V permit--either through initial issuance if
you do not yet have a title V permit, or through a permit revision if
you already have a permit. Including information from the initial NOC
in title V permits should not create the potential for any compliance
conflicts. Because it is the first time the NOC operating requirements
are incorporated into the permit, there would be no requirements
already on permit with which the NOC would conflict.
However, the potential for compliance conflicts could be created
when a subsequent NOC is submitted. For example, you are required to
conduct periodic comprehensive performance testing (see
Sec. 63.1207(d)(1)). Subsequent to each test, you must submit another
NOC to the Administrator. Because of the dynamics of the testing and
permitting cycles, it is possible that once you have information from
the initial NOC in the permit, you could find yourself, after
subsequent testing, in a situation where there might be potentially
conflicting requirements with which you must comply (i.e., requirements
in the title V permit and requirements in the most recently submitted
NOC). This might occur, for example, if any of the operating
requirements changed from the previous test.294 The
potential for compliance conflicts that might arise from this situation
can be avoided, however, by following the guidance presented below.
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\294\ On the other hand, if the limits did not change, there
would be no conflict between the NOC and the permit.
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The requirements in parts 70 and 71 govern the timing and
procedures for permit issuance, revisions, and renewals, and you should
refer to those requirements when obtaining or maintaining your permit.
For today's rule, we provide guidance on what we recommend as to how
operating requirements in the NOC should be incorporated into title V
permits.295
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\295\ We are recommending this approach as guidance in the
preamble, but not including any associated regulatory provisions.
This guidance is essentially an interpretation of the current part
70 and 71 rules.
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[[Page 52978]]
For incorporating information from an initial NOC into a title V
permit, when you have an existing title V permit, we recommend that you
and your permitting agency follow the procedures for significant
modifications. The primary rationale for using these procedures is to
afford the public an opportunity to review all of the information
pertinent to your compliance obligations. We want to ensure a level of
public involvement when including operating requirements in title V
permits that is commensurate with that under RCRA. In RCRA, operating
parameters are initially developed pursuant to trial burns and
incorporated into permits either through initial issuance (in the case
of facilities operating under RCRA interim status) or through a RCRA
class 2 or 3 permit modification (in the case of new facilities). In
either situation, significant opportunities exist for public review and
input parallel to those under initial title V permit issuance or
significant permit modification procedures.
With regard to a subsequent NOC developed pursuant to periodic
performance tests, we prefer an implementation scheme for this rule
that avoids unnecessary permit revisions. Thus, we recommend that you
coordinate your five-year comprehensive performance testing schedule
with your five-year permit term to the extent possible. This would
allow changes in the NOC to be incorporated into the permit at renewal
rather than through separate permit revisions. This also helps to
minimize the number of permit revisions, as well as, the likelihood of
having two sets of requirements with which to comply.
We recognize, however, that such coordination may not always be
possible or feasible. At times, it may be necessary to include
information from the most recent NOC through a permit revision. We
expect that this will be accomplished using, at most, the minor permit
modification procedures in Sec. 70.7(e)(2) or Sec. 71.7(e)(1). Keeping
in mind that the information from the initial NOC was included either
as part of the initial permit issuance or as a significant revision,
the information was already subject to review by both the regulatory
agency and the public. Thus, the public should have a clear
understanding of your compliance obligations. The obligation to comply
with the emissions limitations in Secs. 63.1203, 63.1204, or
Sec. 63.1205 does not change even if any of the associated compliance
information, such as operating limits, is revised pursuant to
subsequent performance tests. Given our experience in regulating (under
RCRA) the types of sources subject to today's MACT standards, we do not
expect the information in a NOC to change significantly over time. We
have been regulating these sources for almost twenty years; the testing
and monitoring requirements we are promulgating in this rule reflect
the ``lessons learned'' over time. Thus, the initial set of compliance
parameters are likely to need primarily minor changes over time. You
and your regulatory agency also are experienced in setting operating
parameter limits and monitoring systems to ensure compliance with
performance standards. Again, this expertise and experience suggests
that primarily minor adjustments will need to be made. In light these
factors, we are confident that changes in the NOC may be appropriately
incorporated into title V permits using the minor permit revisions
procedures. Furthermore, regulatory agencies are obligated under
Sec. 63.1206(b)(3) to make a finding of compliance based on performance
test results. This requirement provides an additional administrative
safeguard to ensure that you are setting the proper operating limits.
The minor permit modification process will allow you to meet your
compliance obligations under Sec. 63.1207(j) and begin to comply with
the conditions in the NOC upon submittal (i.e., post-mark). Under
Secs. 70.7(e)(2)(v) and 71.7(e)(1)(v), you may make the change proposed
in the minor permit modification application immediately after filing
such application. Following this, you must comply with both the
applicable requirements governing the change and the proposed permit
terms and conditions (i.e., the information from the NOC that you are
incorporating into your permit). The provisions in this section also
ensure that you will not be in the position of having to choose between
compliance with the NOC or compliance with your permit because this
section also specifies that during this time period, you need not
comply with the existing permit terms and conditions you seek to
modify.296 Since the NOC is submitted to the Administrator
once you have a title V permit (see Sec. 63.9(h)(3)), we expect that
you will submit the NOC together with a minor permit modification
application. Any modifications added to the permit through this process
can be reviewed by the public at the time of permit renewal.
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\296\ If, however, the source fails to comply with its proposed
permit terms and conditions during this time period, the existing
terms and conditions it seeks to modify may be enforced against it
(Secs. 70.7(e)(2)(v) and 71.7(e)(1)(v)).
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We encourage permitting authorities to develop permits in a way
that minimizes the need for future permit revisions and is consistent
with the requirements in parts 70 and 71. For example, you may request
that your permitting authority develop a permit that contains
alternative operating scenarios. This would allow you to alternate
among various approved operating scenarios while concurrently noting
the change in your operating record.
3. Which RCRA Permitting Requirements Are Applicable?
The RCRA permitting requirements particular to incinerators and
boilers and industrial furnaces are found in 40 CFR 270.19, 270.22,
270.62, and 270.66. These permitting requirements apply to new
facilities, to those operating under interim status while they pursue a
permit, and to sources seeking to renew their permits. In today's final
rule, we amend the introductory text in each of these sections to
reflect that RCRA permitting requirements for hazardous waste combustor
air emissions and related operating parameters will not apply once you
demonstrate compliance with the requirements of the new MACT standards
by completing a comprehensive performance test and submitting a NOC to
the Administrator.297 The timing for the deferral of the
RCRA permitting requirements is consistent with the timing in today's
rule for the deferral of applicable standards in 40 CFR parts 264 and
265.
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\297\ The final rule language in these sections differs from
that in the NPRM to reflect placement of the standards only in part
63 and deferral of RCRA controls to the air program.
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Even though we rely on the title V permitting program to address
air emissions from hazardous waste combustors, we still need RCRA
permits at these sources to address: (1) Other RCRA regulations
applicable to all types of RCRA units, including hazardous waste
combustors, that are not duplicated under the CAA; (2) any risk-based
emissions limits and operating parameters, as appropriate; and (3)
other RCRA units at the facility. Also, new facilities (including new
hazardous waste combustor units) must obtain RCRA permits prior to
starting construction. Thus, the remaining RCRA permitting requirements
in 40 CFR part 270 governing permit applications and permit content
continue to apply. These
[[Page 52979]]
include the provisions in Secs. 270.10(k) and 270.32(b)(2), which
together provide authority to require a facility owner or operator to
submit information necessary to establish permit conditions and to
impose site-specific conditions, including risk-based conditions,
through the RCRA permit.
Even though you will still have two permits, the scope and subject
matter of each are distinguishable. The title V permit will focus on
the operation of the combustion unit (e.g., air emissions and related
parameters) while the RCRA permit will continue to focus on the other
basic aspects of hazardous waste management. The RCRA permit would thus
include conditions to ensure compliance with relevant requirements in
40 CFR part 264, including: General facility standards; preparedness
and prevention; contingency planning and emergency procedures;
manifesting; recordkeeping and reporting; releases from solid waste
management units; closure; post-closure; financial responsibility;
corrective action; storage; materials handling; and air emissions
standards for process vents and equipment leaks from tanks and
containers.
The only time we foresee that conditions in both RCRA and title V
permits may govern the same hazardous waste combustor operating
parameters and limits is when there is a need to impose more stringent
or more extensive risk-based conditions, e.g., under RCRA omnibus
authority, to ensure protection of public health and the environment.
This situation is discussed in greater detail in Part Three, Section IV
(RCRA Site Specific Risk Assessment Decision Process).
4. What Is the Relationship of Permit Revisions to RCRA Combustion
Permitting Procedures?
In June, 1994, we published a proposed rule for RCRA Expanded
Public Participation and Revisions to Combustion Permitting Procedures
(59 FR 28680, June 2, 1994). The proposal contained amended procedures
for interim status combustion facilities during the trial burn period
that were intended to make the procedures for interim status facilities
more like those governing permitted facilities. We finalized the
expanded public participation requirements (see section immediately
below), but did not finalize the proposed permitting revisions. At the
time we began to finalize the proposal, we were already committed to
issuing comprehensive air emissions standards under MACT. It was
anticipated that there would be overlap between the emissions standards
in the proposed MACT rule and the combustion permitting procedures in
the June 1994 proposed rule. It did not make sense to finalize
provisions in one rulemaking effort only to propose changing them yet
again in another rulemaking effort. Now, given the approach being
adopted in today's final rule to permit hazardous waste combustor air
emissions under title V of the CAA, there is no longer as strong a need
to pursue the amended procedures for RCRA permitting in the June 1994
proposal. We do not, therefore, intend at this time to finalize these
proposed permitting amendments.
5. What Is the Relationship to the RCRA Preapplication Meeting
Requirements?
In 1995, we finalized the expanded RCRA public participation
requirements (60 FR 63417, December 11, 1995). These included
requirements for a facility to advertise and conduct an informal
meeting with the neighboring community to discuss anticipated
operations prior to submitting a RCRA Part B permit application. Since
hazardous waste combustors subject to the new MACT standards (and title
V permitting) still need RCRA permits for other hazardous waste
management activities, you are still subject to the RCRA preapplication
meeting requirements in 40 CFR 124.31. Even though operations and
emissions associated with the combustor unit are now to be addressed
primarily under CAA requirements, we anticipate that the public will
continue to exhibit a great deal of interest in combustor activities at
RCRA meetings. They may not always be familiar with our administrative
``boundaries'' dictated by the various environmental statutes. Given
this potential lack of familiarity, and because combustor units and
emissions are already discussed at these meetings, we strongly
encourage you to continue including combustor unit operations in
discussions during RCRA preapplication meetings. Furthermore,
conditions for hazardous waste combustor activities may sometimes be
imposed under RCRA, for example, in cases where the results of a site-
specific risk assessment indicate a need for conditions more stringent
or more extensive than those imposed under MACT. You should be prepared
to discuss the site-specific risk assessment process and how it may
result in additional conditions being included to their RCRA permits.
All other public participation requirements in 40 CFR part 124
associated with the RCRA permitting process continue to apply. These
include requirements for public notice at application submittal, public
notice of the draft permit, opportunity for public comments on the
draft permit, and opportunity for public hearings. These requirements
also are explained in the RCRA Public Participation Manual (EPA530-R-
96-007, September 1996), which provides guidance on how to implement
RCRA public participation requirements, as well as, recommendations on
how to tailor public involvement activities to the situation at hand.
For example, if the community around a facility does not speak English
as a primary language, the manual encourages use of multilingual fact
sheets. As mentioned previously, we encourage you and States to apply
the principles contained in the RCRA manual to hazardous waste
combustor MACT compliance and title V activities as well.
C. Is Title V Permitting Applicable to Area Sources?
Under today's rule, hazardous waste combustors meeting the
definition of an area source will be subject to today's MACT standards
(see discussion in Part One, Section III.B). As discussed in the May
1997 NODA, under Sec. 63.1(c)(2), area sources subject to MACT are
subject to title V permitting as well, unless the standards for that
source category (e.g., subpart EEE for hazardous waste combustors)
specify that: (1) States will have the option to exclude area sources
from title V permit requirements; or (2) States will have the option to
defer permitting of area sources. We received several comments on our
NODA discussion (see 62 FR 24215) on the issue of subjecting area
sources to title V permitting. The comments were fairly evenly split--
several supported requiring area sources to obtain title V permits,
while several were against it. After considering the comments, we have
chosen not to provide the option to the States to exclude hazardous
waste combustor area sources from title V permitting requirements or to
defer permitting of these sources.
Commenters that support the Agency's position affirm that title V
permits serve an important role to incorporate all requirements
applicable to a source in one enforceable permitting document. They
maintain that the compliance certifications and opportunities for
public involvement inherent in the title V program will serve a useful
and valuable public service. Other supporters note that requiring all
hazardous waste combustors to obtain title V permits will help to
ensure that the permits are both consistent and adequate. The idea of
[[Page 52980]]
consistency being a desirable end result is echoed by others as well.
One commenter points out that area sources in several other source
categories are not exempt from title V permitting requirements, and
recommends that hazardous waste combustor area sources also be subject
to title V to maintain consistency with the rest of the MACT program.
Finally, some commenters state that if the Agency were not to pursue
title V permitting for hazardous waste combustor area sources, then the
Agency would have to strengthen the nontitle V permitting programs with
respect to public involvement and agency approval of modifications
relating to facility emissions.
We agree with these points. Title V permits clarify your regulatory
obligation, thereby making it easier for you to keep track of your many
compliance obligations across several air programs. Clarifying the
regulatory obligations improves compliance in many cases; we have seen
an increase in compliance among air sources with the advent of the
title V permitting program. For example, through the process of
applying for and issuing title V permits, applicable requirements of
which a source is unaware or with which it is found to be out of
compliance are identified. Once these requirements are included in a
title V permit, the source must certify compliance with these
requirements both initially and then on an annual basis.
We concur with commenters about the benefits of the public
involvement opportunities afforded by the title V permit program. Our
experience in the RCRA combustion program has shown that many of the
sources that would fall into the area source classification (e.g., some
commercial incinerators and cement kilns burning hazardous waste as
fuel) are the ones in which the public is generally most interested.
Subjecting hazardous waste combustor area sources to title V permitting
will ensure that the public will continue to be involved in permit
decisions under the CAA, as they have been under RCRA. For example, the
public will have an opportunity to comment on and request a public
hearing for a draft title V permit. They have access to State or
Federal court to challenge title V permits, depending upon whether the
permit is a part 70 or part 71 permit. Title V also provides greater
access to information about sources in many cases. Under title V,
States and EPA cannot deny basic information about sources to citizens
unless it is protected as confidential business information.
Conversely, there could be disparity in what information citizens might
be able to obtain under State non-title V operating permits.
Consistency is a key objective as well. Part 70 sets out the
minimum criteria that a State program must meet. If a State fails to
develop and implement a program that meets these minimum criteria, then
a part 71 federal operating permits program is put into place. These
minimum criteria provide for consistency across State and Federal title
V permitting programs, which might not occur under other State air
permitting programs. Consistency within CAA programs is not the only
concern. We also are, as part of our approach to integrating regulation
of these sources under RCRA and the CAA, striving to maintain
consistency with how sources have been regulated under RCRA. Under
RCRA, all of the sources that would fall into an area source
classification are currently treated the same as the sources that are
classified as major under the CAA. It is appropriate to continue
treating all hazardous waste combustor sources in the same manner
(i.e., to apply the same permitting requirements to all of these
sources) under the CAA.
Commenters that do not support applying title V requirements to
area sources generally base their position on three arguments. First,
they argue that Congress had consciously differentiated between area
and major sources when developing the CAA, so that there would be a
strong incentive for facilities to limit emissions and thus avoid the
additional requirements imposed on major sources. These commenters
maintain that subjecting area sources to title V requirements would
create a disincentive for these sources to minimize emissions.
Secondly, they suggest that other CAA permitting mechanisms, such as
federally enforceable state operating permits, might be more
appropriate for the hazardous waste combustor area sources. One
commenter notes that some sources have already invested a lot of time
and effort working with permitting authorities to develop federally
enforceable state operating permits that limit their potential to emit
below major source levels, and that the Agency's action subjecting
these sources to title V permits would render this work meaningless.
Finally, they assert that this would be the first time the Agency did
not provide the option to the States to either defer title V permitting
for area sources or exempt them entirely, and they express concern
about the precedent that would be set if the Agency were to start
requiring area sources to obtain title V permits in this rule.
After careful consideration, we are not persuaded by these counter-
arguments. Although the CAA does differentiate in some provisions
between area and major sources, it did not specify that area sources
should be exempt from the title V permitting program. On the contrary,
it provides discretionary authority in section 502(a) for the
Administrator to decide whether to exempt a source category, in whole
or in part, from title V permitting requirements. Furthermore, the
implementing regulations in 40 CFR 70.3(b)(2), 71.3(b)(2), and
63.1(c)(2) specify that the Administrator will determine whether to
exempt any or all area sources from the requirement to obtain a title V
permit at the time new MACT standards are promulgated. Clearly, the
decision to subject area sources to title V permitting is intended to
be made in the context of both the source category and the applicable
standards. The exemption from title V may only be provided if
compliance with the requirements would be ``impracticable, infeasible,
or unnecessarily burdensome.'' CAA section 502(a). Given that the
hazardous waste combustors subject to today's rule, including those
that may meet the definition of area sources, have all been subject to
common permitting regulations under RCRA, subjecting these sources to
title V permitting is not impracticable, infeasible, or unnecessarily
burdensome. Furthermore, if we exempt area sources from title V
permitting requirements, we would most likely have continued to apply
RCRA permit requirements for stack emissions to these sources. Thus,
the area sources would have been subject to dual permitting regimes
(e.g., federally enforceable state operating permits under the CAA and
RCRA permits) and the resulting burden associated with duplicative
regulation. This would be contrary to a major goal of today's rule. In
conclusion, we decided that it is appropriate to subject all hazardous
waste combustor sources subject to today's MACT standards to title V
permitting requirements. As noted earlier in this preamble, this is
also consistent with the Congressional scheme under RCRA that mandates
regulation of all hazardous waste combustors for all pollutants of
concern.
Although we provided the option to defer title V permitting for
some area sources subject to other MACT standards, this rule is not the
first time we have not allowed States to defer area sources from title
V requirements. See, e.g., 64 FR 31898, 31925 (June 14, 1999) (NESHAP
for Portland Cement Manufacturing Industry to be codified at
[[Page 52981]]
40 CFR part 63, subpart LLL). Moreover, EPA regulations governing other
categories of solid waste combustors under CAA section 129 do not
differentiate between major and minor sources in imposing title V
permitting requirements. See, e.g., CAA section 129(e); 40 CFR 70.3(a)
and 70.3(b)(1), and 40 CFR 60.32e(i). Given that the decision to apply
title V requirements is made in a specific context, we do not share
commenters' concern about the precedent our approach might set for
other situations. We will continue to evaluate each situation on its
own merit. Finally, we do not agree with commenters that this approach
will provide a disincentive to limit emissions because sources will
still be ``capped'' by the emissions limits being promulgated in
today's rule. Neither would progress already achieved in developing
federally enforceable state operating permits be rendered meaningless,
as suggested by some commenters. We anticipate that a source will
likely be able to use the information gathered during the process of
developing a federally enforceable state operating permit (e.g.,
information about its emissions and applicable requirements) in
completing a title V application. Commenters appear to think that
sources will have to start totally anew and without an ability to use
past experience and results. This is neither a realistic nor practical
view of how sources are likely to act.
Commenters opposed to subjecting hazardous waste combustor area
sources to title V had also noted that these sources would be receiving
RCRA permits for the air emissions as well. This argument would have
merit if we choose to promulgate the new standards in both CAA and RCRA
regulations. Since we are promulgating the MACT standards only in the
CAA regulations, however, requirements on air emissions from hazardous
waste combustor area sources would not be included in RCRA
permits.298 Commenters also discount our position in the
NODA about difficulties that would arise if an area source were to move
from one permitting program to another as they make modifications to
their emissions levels that could change their major/area source
determination. They point to our ``once in, always in'' approach to
MACT standards that is stringently applied. Under this approach, once a
MACT standard goes into effect, a major source will always be regulated
under that standard, even if it later decreases its emissions to below
major source levels. This ensures that sources cannot routinely
``flip'' between being regulated or unregulated, which in turn means
that sources would not be moving in and out of the title V permitting
universe. The commenter was correct in raising this to our attention.
We are not relying on this argument to support our decision to subject
hazardous waste combustor area sources to the standards or to title V.
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\298\ The exception would be, as discussed earlier, cases where
States, at their own choosing, have incorporated the HWC MACT
standards into their State RCRA programs.
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D. How will Sources Transfer from RCRA to MACT Compliance and Title V
Permitting?
1. In General, How Will this Work?
As discussed in Section A (Placement of Standards and Approach to
Permitting), we are deferring RCRA controls on hazardous waste
combustor air emissions to the part 63 hazardous waste combustor MACT
standards, which are ultimately incorporated into title V permits
issued under the CAA. Promulgation of the new hazardous waste combustor
MACT standards under the CAA does not, however, by itself implement
this deferral or eliminate the need to continue complying with
applicable RCRA requirements--either those in a source's RCRA permit or
in RCRA interim status performance standards. These requirements
include obligations for RCRA permitting (for example, interim status
facilities will continue to be subject to RCRA permitting requirements,
including trial burn planning and testing).
Therefore, today's rule adopts specific provisions that address the
transition from RCRA permitting to the CAA regulatory scheme. As
discussed in Section B.3 (Applicability of RCRA permitting
requirements), the requirements in Secs. 270.19, 270.22, 270.62, and
270.66 do not apply once a source demonstrates compliance with the
standards in part 63 subpart EEE by conducting a comprehensive
performance test and submitting an NOC to the regulatory
agency.299 In this section, we discuss how regulators can
implement the deferral from RCRA to hazardous waste combustor MACT
compliance and title V permitting.
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\299\ If, however, there is a need to collect information under
Sec. 270.10(k) then the permitting authority may require, on a case-
by-case basis, that facilities use the provisions found in these
sections.
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a. What Requirements Apply Prior to Compliance Date? You have three
years following promulgation of the MACT standards to achieve
compliance with the emissions standards. However, the rule is effective
shortly after promulgation. During the approximately three years
between the effective date and the compliance date, you will be subject
to applicable requirements for hazardous waste combustor MACT
compliance and title V permitting. For example, there are compliance-
related requirements in 40 CFR part 63 subpart EEE that are separate
from the actual standards for emissions levels, such as those in
Secs. 63.1210(b) and 63.1211(b) for submitting a Notice of Intent to
Comply and a progress report, respectively. Requirements in 40 CFR
parts 70 and 71 for operating permit programs developed under title V
will also apply. These include requirements governing timing for
submitting initial applications, reopenings to include the standards,
and revisions to incorporate applicable requirements into title V
permits. The interface between an NOC and the title V permit has
already been discussed. Consequently, our discussion on implementing
the deferral of RCRA controls focuses on the transition away from RCRA
permits and permit processing once a facility demonstrates compliance
with the standards through a comprehensive performance test and submits
a NOC to the regulatory agency.
Many of the activities undertaken during the three year compliance
period play a role in implementing the transition of RCRA controls to
MACT compliance and title V. For example, some of you may have to make
changes to their design or operations to come into compliance with the
new standards. If you have a RCRA permit, you may need to modify the
RCRA permit to reflect any of these changes before they are actually
made. This may be necessary to remain in compliance with the RCRA
permit while setting the stage for demonstrating compliance with CAA
MACT requirements. We urge you (the source) to seek guidance from your
RCRA permitting authorities as early as possible in this process. As
part of our ``fast track rule'' (see 63 FR 33781, June 19, 1998), we
promulgated a streamlined process in 40 CFR 270.42(j) for modifying the
RCRA permit, so that you can make these necessary changes and begin
operating in accordance with the new limits before the compliance date
arrives. To take advantage of the streamlined process, however, you
must first comply with the Notice of Intent to Comply requirements in
Sec. 63.1210. The Notice of Intent to Comply requirements obligate you
to advertise and conduct an informal meeting with the neighboring
community to discuss plans to comply with the new standards, and to
subsequently provide information about
[[Page 52982]]
these plans to the regulatory agency.300 We anticipate
discussion at this meeting will include modifications to the RCRA
permit that must be processed before you can start upgrading equipment
to meet the emissions limits set by MACT. The goal of these activities
is to ensure that by the end of the three-year compliance period, you
will be in compliance with both the MACT standards and their RCRA
permits or interim status requirements.
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\300\ The requirements for providing notice of and conducting
the public meeting as part of the Notice of Intent to Comply
provisions are based on the RCRA preapplication meeting requirements
in 40 CFR 124.31.
---------------------------------------------------------------------------
b. What Requirements Apply After Compliance Date? After the
compliance date, a transition period exists during which there will be,
in effect, two sets of standards concerning emissions from hazardous
waste combustors: (1) The MACT standards in 40 CFR part 63; and (2) the
performance standards that are still in the RCRA permit or in the 40
CFR part 265 interim status regulations. During this period, in cases
where operating parameters and limits are addressed by both programs
(MACT and RCRA), you must comply with all applicable parameters and
limits; those which are more stringent will govern. We anticipate that
the MACT standards will be compatible with the RCRA performance
standards, although in some cases the DOC is likely to set narrower or
different operating conditions. Thus, in complying with the MACT
standards, you also will comply with corresponding conditions in the
RCRA permit or in the RCRA interim status regulations. However, at some
sites, certain RCRA permit conditions may be more stringent than the
corresponding MACT standards or may establish independent operating
requirements. Some potential reasons why such a situation would occur
are discussed in the May 2, 1997 Notice of Data Availability (62 FR
21249, 5/2/97). In these situations, you must comply with the more
stringent or more extensive conditions in the RCRA permit.
We also note that there may be situations where it is not clear
whether a RCRA compliance requirement is less stringent than a MACT
requirement. This can occur, for example, when the two compliance
requirements have different averaging periods and different numerical
limits. In this situation, we recommend that the source coordinate with
permitting officials early in the MACT process, perhaps when the source
submits RCRA permit modification pursuant to the fast-track rulemaking,
in order to determine which requirement is more stringent. We believe
the permitting officials should give sources an appropriate level of
flexibility when making this determination.
Our approach of placing the MACT air emission standards for
hazardous waste combustors in 40 CFR part 63 subpart EEE and not
including them, even by reference, in the RCRA regulations means that
the air emissions must ultimately be incorporated into title V permits
issued under the CAA. To completely implement the deferral of RCRA
controls, conditions governing air emissions and related operating
parameters should also be ultimately removed from RCRA permits. (For
the special case of risk-based conditions derived from RCRA omnibus
authority, see earlier discussions.) Similarly, hazardous waste
combustors that are in the process of obtaining RCRA permits will
likely need to have the combustor air emissions and related parameters
transitioned to MACT compliance and title V permits at some point.
We intend to avoid duplication between the CAA and RCRA programs.
We encourage you and regulators to work together to defer permit
conditions governing air emissions and related operating parameters
from RCRA to MACT compliance and title V, and to eliminate any RCRA
provisions that are no longer needed from those permits. As discussed
below, we are adopting a provision in today's final rule to help
permitting authorities accomplish this task in the most streamlined way
possible. The RCRA permits will, of course, retain conditions governing
all other aspects of the hazardous waste combustor unit and the rest of
the facility that continue to be regulated under RCRA (e.g., general
facility standards, corrective action, financial responsibility,
closure, and other hazardous waste management units). Furthermore, if
any risk-based site-specific conditions have been previously included
in the RCRA permit, based either on the BIF metals and/or hydrochloric
acid/chlorine requirements 301 or the omnibus authority, the
regulatory authority will need to evaluate those conditions vis-a-vis
the MACT standards and the operating parameters identified in the NOC.
If the MACT-based counterparts do not adequately address the risk in
question, those conditions would need to be retained in the RCRA permit
or included within an appropriate air mechanism. In those limited
cases, sources and permitting agencies may instead agree to identify
the RCRA limit in the title V permit. Since one goal of the title V
program is to clarify a source's compliance obligations, it will be
beneficial, and convenient, to acknowledge the existence of more
stringent limits or operating conditions derived from RCRA authority
for the source in the title V permit, even though the requirements
would not reflect CAA requirements. We strongly encourage Regional,
State, and local permitting authorities to take advantage of this
beneficial option.
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\301\ The BIF limits for metals under RCRA are based on
different level of site-specific testing and risk analysis (Tier I
through Tier III). It is possible that, if it were based on the more
stringent analysis, a RCRA BIF limit could be more stringent than
the corresponding MACT standard.
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2. How Will I Make the Transition to CAA Permits?
In the May 1997 NODA, we expressed our intent to rely on the title
V permitting program for implementation of the new standards, and asked
for comments on how and when the transition from RCRA should occur (see
62 FR 24250, May 2, 1997). We are amending the regulations in 40 CFR
part 270 to specify the point at which the RCRA regulatory requirements
for permitting would cease to apply. However, once you have a permit,
you must comply with the conditions in that permit until they are
either removed or they expire. Many commenters expressed an interest in
what happens to conditions in a RCRA permit once the new standards are
published. We received a variety of suggestions, but a common thread
was a request for EPA to lay out a clear path through the permit
transition process. While we recognize the desirability of having a
uniformly defined route for getting from one permit to another, it is
important to provide flexibility to allow a plan that makes the most
sense for the situation at hand. There is not a ``one size fits all''
approach that would be appropriate in all cases. Thus, we are not
prescribing a transition process via regulation, but providing guidance
in the following discussion which we hope will assist regulatory
agencies in determining a route that makes the most sense in a given
situation. Given the level of interest expressed, we will, in the
ensuing discussion, map out a process for implementing the deferral of
air emissions controls from RCRA to MACT compliance and title V
permitting. We address key considerations that should factor into the
decision of how and when to implement the deferral of permit
conditions.302
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\302\ Although we are not mandating an approach to transition by
regulation, we are, as discussed in Section 2. How Should RCRA
Permit Be Modified? below, providing a tool in the RCRA permit
modification table in 40 CFR 270.42, Appendix I, that may be used to
assist regulators and sources in effecting the transition.
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[[Page 52983]]
In identifying key aspects of the transition, we seek the optimal
balance of three basic considerations raised by commenters and other
stakeholders. The considerations are to: (1) Address public perception
issues associated with taking conditions out of a RCRA permit; (2)
minimize the amount of time a source might be potentially subject to
overlapping requirements of RCRA and the CAA (and thus subject to
enforcement under both RCRA and the CAA for the same violation); and
(3) provide flexibility to do what makes the most sense in a given
situation. The first two considerations are primarily factors of time--
when should conditions be removed from the RCRA permit? The third
consideration is more a factor of how--what mechanism should be used
for removing RCRA conditions?
Why do these particular considerations carry such importance? As
for the first, one of the points emphasized in our National Hazardous
Waste Minimization and Combustion Strategy is the importance of
bringing hazardous waste combustors under permits as quickly as
possible. The Strategy has been driving EPA Regions and authorized
States to place their top permitting priority on the hazardous waste
combustor universe. Consequently, the Strategy may have created a
certain perception on behalf of the public about the importance of the
actual permit document. The actual issue we are trying to address here
is more of a concern about a potential break in regulatory coverage of
a source as it transitions from RCRA permitting requirements to the CAA
regulatory scheme.
While it might appear that we are altering the policy expressed in
the Strategy if we allow removal of conditions from a RCRA permit
before the title V permit is in place, it is not the actual permit
document that is of paramount importance. Rather, our focus is and has
been on maintaining a complete and enforceable set of operating
conditions and standards. One of the underlying tenets of the position
taken on permitting in the Combustion Strategy was a commitment to
bring hazardous waste combustors under enforceable controls that
demonstrate compliance with performance standards. Under RCRA, the
permit was the available vehicle to achieve better enforcement of
tighter conditions than exist in interim status.
We remain committed to this underlying tenet. However, the
mechanism for achieving this objective under the CAA is not necessarily
the title V permit. In RCRA, the permitting process provides the
vehicle for the regulatory agency to approve testing protocols
(including estimated operating parameters), to ensure completion of the
testing, and to develop final operating parameters proven to achieve
performance standards. The final RCRA permit is the culmination of
these activities. Under MACT, these activities do not culminate in a
permit, but in a NOC. The development of the NOC is separate from the
development of the title V permit. The title V permitting process is
primarily a vehicle for consolidating in one document all of the
requirements applicable to the source. Conversely, it is the NOC that
contains enforceable operating conditions demonstrated through the
comprehensive performance test to achieve compliance with the hazardous
waste combustor MACT standards (which are generally more stringent than
the RCRA combustion performance standards). Thus, the NOC captures the
intent of the Strategy with regard to ensuring enforceable controls
demonstrated to achieve compliance with relevant standards are in
place.
Another basis for our position on permitting in the Combustion
Strategy is the level of oversight by the regulatory agency during the
permitting process, which is typically greater than that which occurs
during interim status. For example, although BIFs operating under
interim status are required to conduct compliance testing and
subsequently operate under conditions they identify in a certification
of compliance, there are no requirements for the regulatory agency to
review and approve compliance test plans or results. On the other hand,
oversight by the regulatory agency is more intensive during the
permitting process, e.g., through the trial burn planning (including
regulatory approval of the trial burn plan), testing, and development
of permit conditions. Although the process required for interim status
BIFs under RCRA may, at first, seem analogous to the CAA MACT process,
i.e., sources being required to conduct comprehensive performance tests
and subsequently operate under conditions in an NOC, there is a
significant difference. The difference is the level of oversight that
occurs in the MACT process. According to the MACT requirements in 40
CFR 63.1207(e) and 63.1206(b)(3), the regulatory agency must review and
approve the performance test protocol and must make a finding of
compliance based on the test results that are reported in the NOC. The
NOC consequently represents a level of agency oversight that is
actually more analogous to the RCRA permit process than to interim
status procedures.
An additional reason for the importance, under the Combustion
Strategy, of bringing hazardous waste combustors under permits was to
allow for the imposition of additional permit conditions where
necessary to protect human health and the environment. In general,
these conditions are established based on the results of a site-
specific risk assessment and imposed under the RCRA omnibus authority.
This objective will continue to be met even though we are deferring
regulation of hazardous waste combustor air emissions, in general, to
the CAA. Coming into compliance with the more stringent and more
encompassing MACT standards will accomplish part of the Combustion
Strategy's goal of improved protection. For any cases where the
protection afforded by the MACT standards is not sufficient, the RCRA
omnibus authority and RCRA permitting process will continue to be used
to impose additional conditions in the RCRA permit (or, as discussed
earlier, in a title V permit).
With regard to the remaining considerations, we seek here to reduce
duplicative requirements across environmental media programs (i.e., air
emissions under the CAA and RCRA). This objective to reduce duplication
is behind our goal of minimizing the amount of time a source might be
potentially subject to dual permitting and enforcement scenarios. In
order to allow for common sense in implementing environmental
regulations, we need to provide flexibility here to do what makes sense
in a given situation. We have provided this flexibility in today's rule
by not prescribing only one process for transitioning from RCRA to the
CAA.
3. When Should RCRA Permits Be Modified?
We identified two options in the May, 1997, NODA for when
conditions should be ultimately removed from RCRA permits (see 62 FR
24250). Our preferred option at the time is to wait until the source
had completed its comprehensive performance test and the standards had
been included in its title V permit. The alternative option we
identified would be to modify the RCRA permit once the facility submits
the results of its comprehensive performance test.
[[Page 52984]]
Of the comments that spoke to the timing issue, some advocate
waiting for the title V permit, but most opposed this position. The
majority of commenters favor effecting the transition either on the
compliance date, since we had said in the NODA that the pre-NOC would
be due to the regulatory agency on that date 303 and would
contain enforceable conditions, or upon submittal of the NOC, since it
contains enforceable operating conditions demonstrated to achieve
compliance with the standards. All three of these approaches are
identified in the time line shown in Figure 1. Readers will note that
the time line shows two potential points for the title V permit to be
issued (options 1A and 1B). Option 1A is based on the statutory time
frames for issuing title V permits. Under this option, the title V
permit may be issued prior to the compliance date for the new
standards, but it might only include the standards themselves and a
schedule of compliance. Under option 1B, the operating requirements in
the NOC that actually have been demonstrated to achieve compliance
would be included in the permit.
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\303\ We are adopting a DOC (previously the pre-NOC) requirement
in today's final rule, but it is amended from how we presented it in
the NODA (as discussed in Part Five, Section IV). Rather than
submitting the DOC to the regulatory agency, a source must maintain
it in their operating record. We encourage source owners and
operators to set up the operating record in an unrestricted location
that is reasonably accessible by the public.
---------------------------------------------------------------------------
We evaluated each of the options in terms of the two timing-related
considerations listed above: addressing the perception issue that stems
from removing conditions from the RCRA permit (which, as discussed
above, is really a concern about a break in regulatory coverage--i.e.,
that there might be a period of time when the source would not have
enforceable controls demonstrated to achieve compliance with stack
emissions standards), and minimizing the amount of time sources would
potentially be subject to the same requirement(s) under both RCRA and
CAA. These considerations may not always be compatible. For example,
one way to address the perception of creating a break in regulatory
coverage would be to continue to place emphasis on the permit, rather
than on the tenet behind the permit (of having enforceable controls
that demonstrate compliance with performance standards). This would
mean waiting to remove conditions from a RCRA permit until a source has
demonstrated compliance with the MACT standards and incorporated the
appropriate combustion operating requirements in its NOC into the title
V permit (i.e., option 1B). However, this approach would maximize the
amount of time the source potentially would be subject to overlapping
requirements under RCRA and the CAA. On the other hand, one way to
address the overlapping requirements consideration would be to allow
removal of conditions from the RCRA permit at the time the standards
are promulgated. But, this would create a time period during which the
source would not have enforceable controls proven to achieve
compliance, which would not address the concern about avoiding a break
in regulatory coverage. Clearly neither of these extremes can provide a
good balance between the two timing-related considerations.
BILLING CODE 6560-50-P
[[Page 52985]]
[GRAPHIC] [TIFF OMITTED] TR30SE99.006
[[Page 52986]]
[GRAPHIC] [TIFF OMITTED] TR30SE99.007
BILLING CODE 6560-50-C
[[Page 52987]]
We evaluated each option to determine which most effectively
balances the relevant issues. Options 1A and 1B focus primarily on
tying the transition timing to title V permitting. Option 2 links the
timing for transition to the DOC (previously called the pre-NOC).
Option 3, which we are recommending be followed, ties transition to
submittal of the NOC.
a. Option 1A. This option is a variation of an option discussed in
the May, 1997, NODA. There we stated, ``The Agency's current thinking
is that the RCRA permit should continue to apply until a facility
completes its comprehensive performance testing and its title V permit
is issued (or its existing title V permit is modified) to include the
MACT standards. The RCRA permit would then be modified to remove the
air emissions limitations which are covered in the title V permit.''
(see 62 FR 24250). Although this description basically applies to
option 1B, the discussion in the NODA might also have been interpreted
to mean that once the standards are in a title V permit, the
corresponding emissions limits should be removed from the RCRA permit.
When reviewing the implementation time line in terms of the statutory
and regulatory time frames governing the title V process, we found that
sources might well have title V permits issued or modified to include
the new standards a year before they ever conduct performance testing.
Although the permit would likely include the standards and a schedule
for complying with the new limits, it would not include any of the key
combustion operating requirements demonstrated in the performance test.
Thus, even though option 1A would seem to address the concern about a
break in coverage because the title V permit would have been issued, in
actuality, the underlying tenet of the Combustion Strategy--that the
source have enforceable operating parameters proven to achieve the new
standards--is not fully addressed.
b. Option 1B. This option calls for the NOC to be incorporated into
title V permits before any conditions could be removed from RCRA
permits. As discussed earlier, this approach would not be consistent
with our goal of minimizing duplication across permitting programs,
even though it was identified as our current thinking in the NODA. As
discussed in the NOC/title V Interface Section, the initial NOC must be
incorporated into the title V permit as a significant permit
modification, which could add another nine months to the transition
period. Moreover, commenters express concern over impacts that existing
delays in title V permitting activities might have. Commenters wrote
that given the tremendous volume of permits to be issued (hazardous
waste combustors being just one small subset) there would be no way to
predict how long it might take regulatory agencies to initially issue
or modify title V permits to include the standards, or to modify
permits to include NOCs, despite time frames set forth in the title V
regulations. We agree that delaying removal of air emissions and
related parameters from RCRA permits until this occurs would
unnecessarily extend the amount of time sources might be subject to
overlapping requirements. As pointed out by commenters, having
overlapping requirements may present technical and administrative
difficulties. Examples of technical difficulties include, but are not
limited to, the potential for conflicting requirements with regard to
testing, monitoring, and compliance certifications. Examples of
administrative difficulties include, but are not limited to, permit
maintenance issues stemming from different permit modification
procedures and appeals procedures.
c. Option 2. Option 2 reflects the time frame suggested by some
commenters for effecting the transition upon submittal of the DOC,
which, under the NODA discussion, would have been due to the regulatory
agency on the compliance date (note: commenters appear to use the terms
``compliance date'' and ``effective date'' interchangeably, but they
are quite different). Basing transition on the DOC was still a viable
option to consider, even with our amended approach of having the source
maintain the DOC in its operating record. The DOC contains enforceable
operating conditions for key combustion parameters that the source
anticipates will achieve compliance with the new standards. Although
the source would have had to comply with other enforceable part 63
requirements by this point (e.g., requirements for the Notice of Intent
to Comply, the progress report, and the performance test plan), this
would be the first point where a source might have overlapping
requirements governing air emissions and related operating parameters--
those in the DOC and those in the RCRA permit. Recommending removal of
RCRA permit conditions at this point would thus minimize the potential
for duplicative requirements. However, we conclude that it would still
not address the perception issue adequately. Specifically, even though
the source is subject to enforceable operating requirements, the source
has not actually demonstrated compliance with the new standards.
d. Option 3. This option reflects the alternative approach we
suggested in the May, 1997, NODA, as well as the preferred option of
the majority of those who submitted comments on the timing issue. Under
this recommended option, a source might well have a title V permit that
addresses the new standards to some extent, even if just by including
the standards themselves and a schedule for compliance. More
importantly, the source will have conducted its comprehensive
performance test, and submitted an NOC containing key operating
parameters demonstrated to actually achieve compliance (and which are
enforceable). Although there would be some time during which a source
might have overlapping requirements (those in its NOC and those in its
RCRA permit), this would be a finite and predictable amount of time.
After considering all the comments, we conclude that option 3 best
meets the dual challenges of ensuring the source is continuously
subject to enforceable controls demonstrated to achieve compliance
while minimizing the time you would be subject to permitting
requirements for, and enforcement of, operating parameters and limits
under both RCRA and the CAA. Therefore, today's rule adopts option 3.
We acknowledge that this approach does not completely eliminate
concerns expressed by some commenters about the potential for
facilities to be subject to dual enforcement mechanisms. Although this
potential may exist during the brief transition period when a source
has enforceable conditions under both CAA and RCRA, we will exercise
enforcement discretion to avoid any duplicative inspections or actions,
and we encourage States to do so as well. If any inspections are
scheduled to occur during the brief transition period (which may be
unlikely given how short this period is), the regulatory agency could
conduct joint inspections by RCRA and CAA enforcement staff. Joint
inspections might help to alleviate some of the potential for any
duplicative efforts, either in terms of individual inspections
targeting the same areas, or enforcement actions being taken under both
RCRA and CAA authorities.
Under Option 3, you would most likely have a title V permit that
addresses the hazardous waste combustor MACT standards to some extent.
We expect that if the permit were issued prior to the comprehensive
performance test and the submittal of the NOC, it would contain the
standards
[[Page 52988]]
themselves, and related requirements in part 63 subpart EEE, such as
the requirements to develop and public notice performance test
protocols, to develop and maintain in its operating record the DOC with
anticipated (and enforceable) operating limits, to conduct the
comprehensive performance test and periodic confirmatory tests, and to
submit the NOC, including the test results, to the regulatory agency.
The public would have had an opportunity to comment on the
requirements in the title V permit as part of the normal CAA
administrative process for issuing permits. Furthermore, the public
would have had other opportunities to be involved in your compliance
planning. For example, under the requirements for the Notice of Intent
to Comply in Sec. 63.1210(b), you would have had to conduct an informal
meeting with the community to discuss how you intend to come into
compliance with the new standards. You also are required in
Sec. 63.1207(e) to provide public notice of the performance test plan,
so the public would have the opportunity to review the detailed testing
protocol that describes how the operating parameters will achieve
compliance.
4. How Should RCRA Permits Be Modified?
Once you have been issued a RCRA permit, you must comply with the
conditions of that permit. Unless the conditions have been written into
the permit with sunset (i.e., automatic expiration) clauses governing
their applicability, conditions remain in effect until the permit is
either modified to remove them or the permit is terminated or expires.
Promulgation of final MACT standards for hazardous waste combustors
does not in itself eliminate your obligation to comply with your RCRA
permit. In the May 1997 NODA, we stated that the RCRA permit would be
modified to remove air emission limitations that are covered under
MACT, but did not elaborate on what modification procedures would be
followed. We solicited comments on how the transition should occur.
Of the commenters that addressed this issue, the recurring theme in
the comments is for EPA to provide a mechanism that would impose
minimal burden on sources and permit writers to process the
modifications. Some express a desire to see the RCRA conditions removed
in some automatic fashion once the MACT standards became effective. A
mechanism for accomplishing this, suggests one commenter, would be to
include a requirement in the final rule that would effect removal of
conditions from all RCRA permits. One commenter suggests adding a new
line item to Appendix I in Sec. 270.42, designated as class 1, to
address the transition to MACT. Another suggests a new line item
designated as class 1 requiring prior agency approval. A third suggests
a new line item designated as class 2.
We do not agree with eliminating conditions from all RCRA permits
as part of a national rulemaking effort (i.e., we do not agree with an
``automatic'' removal), particularly given the existence of authorized
sate programs and state-issued permits. Permits may contain site-
specific conditions developed to address particular situations, e.g.,
conditions based on the results of a site-specific risk assessment. To
ensure that the regulatory agency continues to meet its RCRA obligation
to ensure protection of human health and the environment, these
conditions may need to be evaluated on a case-by-case basis vis-a-vis
the MACT standards before they are removed. If the RCRA risk-based
conditions are more stringent or more extensive than the corresponding
MACT requirements, the conditions must remain in the RCRA permit.
We do agree with commenters that there should be a streamlined
approach to removing conditions from a RCRA permit that are covered by
the hazardous waste combustor MACT regulations at the time an NOC
demonstrating compliance is submitted to the regulatory agency. All
other conditions would, of course, remain in the RCRA permit. Once you
demonstrate compliance with MACT, we consider the transition from RCRA
to be primarily an administrative matter since you will not only be
subject to comparable enforceable requirements under CAA authority, but
also will continue to be subject to any site-specific conditions under
RCRA that are more stringent than MACT. Our intent is not to impose an
additional burden on you or permit writers for a largely administrative
requirement. To this end, we are adding a new line item to the permit
modification table in 40 CFR 270.42, Appendix I, to specifically
address the transition from RCRA to the CAA.
The approach of adding a new line item to the permit modification
table is consistent with the comments we received pursuant to the May
1997 NODA. We agree with the commenter who suggests the new item be
designated as a class 1 modification requiring prior Agency approval.
This classification effectively balances the need to retain some
regulatory oversight of the changes with the goal of minimizing the
amount of time a source will be subject to regulation under both RCRA
and the CAA for essentially the same requirements. A class 1
modification without prior approval, suggests one commenter, would not
be sufficient to accomplish the transition with adequate confidence in
proper regulatory coverage. Even though we consider the deferral to be
an administrative matter, it is important to retain some level of
regulatory oversight prior to effecting the change to provide the
opportunity to address any differences between the two programs. On the
other hand, the administrative exercise of transitioning from RCRA to
the CAA does not warrant the extra measures (and attendant time
commitment) of a class 2 modification procedure.
We are designating the new line item (A.8.) in the Appendix I table
as class 1 requiring prior Agency approval. Thus, the administrative
procedures associated with this mechanism will not be overly
burdensome, yet RCRA permit writers will have an opportunity to confer
with their counterparts in the air program prior to approving the
request to eliminate conditions from the RCRA permit. This allows the
RCRA permit writer to verify that you have completed the comprehensive
performance test and submitted your NOC. In the few situations where
site-specific, risk-based conditions have been incorporated into RCRA
permits, it also provides the RCRA permit writer with the opportunity
to review such conditions vis-a-vis the MACT standards to ensure any
conditions that are more stringent or extensive than those applicable
under MACT are retained in the RCRA permit. The public also would be
informed that the transition from RCRA was being effected because the
modification procedures require a notice to the facility mailing list.
We recommend that the public notice for the RCRA permit modification
also briefly mention that you have completed performance testing under
the CAA, and are operating under enforceable conditions that are at
least as stringent as those being removed from your RCRA permit.
One commenter offered suggestions for preparing the RCRA
modification requests. We found some of these suggestions helpful and
recommend that, to facilitate processing of the RCRA modification
requests, you (1) identify in your modification requests which RCRA
conditions should be removed, and (2) attach your NOC to the requests.
From another perspective, today's approach for removing conditions
from the RCRA permit also may encourage
[[Page 52989]]
you to work closely with the air program to expeditiously resolve any
potential or actual disagreements on the results of the comprehensive
performance test and conditions in the NOC. The RCRA permit writer is
not likely to approve the modification request until he or she has
received confirmation that their air program counterpart is satisfied
with your compliance demonstration under MACT (i.e., that they have
made the finding of compliance based on the test results documented in
the NOC, as discussed in the following paragraph). Thus, you should
continue to be subject to requirements under both RCRA and the CAA
until the differences, if any, are resolved.
We are not including a requirement in either part 63 subpart EEE or
part 270 specifically for the regulatory agency to approve the NOC
before approving the RCRA modification request. We have incorporated
the general provision for making a finding of compliance (see
Sec. 63.6(f)(3)) into the requirements of subpart EEE at
Sec. 63.1206(b)(3). According to these provisions, the regulatory
agency has an obligation to make a finding of compliance with
applicable emissions standards upon obtaining all of the compliance
information, including the written reports of performance test results.
Because of this obligation, air program staff currently review stack
test results that are submitted in NOCs subsequent to performance
testing, and routinely transmit an official letter to you indicating
the acceptability of the test results. Furthermore, if you fail the
comprehensive performance test, there are requirements in part 63
subpart EEE specifying what you must then do. Given this combination of
regulatory obligations and current practices, we see no need to impose
additional requirements governing review of performance test results.
This approach is also consistent with the timing for when permit
requirements are deferred to CAA (see the amended rule language for 40
CFR 270.19, 270.22, 270.62, and 270.66)).
5. How Should Sources in the Process of Obtaining RCRA Permits Be
Switched Over to Title V?
In the initial NPRM and the May, 1997, NODA, we did not
specifically describe, or solicit comment on, permit process issues for
facilities operating under RCRA interim status, or facilities seeking
to renew their RCRA permits (which can occur even after the nominal
permit term has expired). In the above sections, we focused on
implementing the deferral of RCRA controls by determining how and when
to move conditions out of existing RCRA permits. For facilities that do
not yet have RCRA permits, or that need to renew their RCRA permits,
the focus of the discussion shifts to how and when to move nonrisk-
based air emissions considerations out of the RCRA permitting process.
As indicated earlier, RCRA interim status facilities will continue to
be subject to RCRA permitting requirements for air emissions standards
and related operating parameters, including trial burn planning and
testing, until they have demonstrated compliance with the new standards
by conducting a comprehensive performance test and submitting an NOC to
the agency. Facilities in the process of renewing their RCRA permits
will also continue to be subject to RCRA permitting requirements until
the same point.
Again, there is no single approach for moving these two categories
of facilities out of the RCRA permitting process (i.e., for stack air
emissions requirements). The most appropriate route to follow in each
case depends on a host of factors, including, for example: (1) The
status of the facility in the RCRA permitting process at the time this
rule is published; (2) the priorities and schedule of the regulatory
agency; (3) the level of environmental concern at a given site; and (4)
the number of similar facilities in the permitting queue. The
regulatory agency (presumably in coordination with the facility) will
balance all of these factors. In mapping out a site-specific approach,
we are encouraging permitting agencies to give weight to two key
factors. First, we should minimize to the extent practicable the amount
of time a facility would be subject to duplicative requirements between
RCRA and CAA programs. Second, as indicated in Part Five, Section V.B
(Risk Burn/Comprehensive Performance Testing), testing under one
program should not be unnecessarily delayed in order to coordinate with
testing under the other. For example, if a facility is planning to
conduct a RCRA trial burn within a fairly short amount of time after
the rule is promulgated, they generally should not be allowed to delay
the trial burn to coordinate with comprehensive performance testing
under MACT that may not occur for three more years.\304\
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\304\ There may be a short delay allowed for the purpose of
combining RCRA trial burn and MACT performance test plans. Of
course, even if the timing for the two tests is such that they may
be coordinated, that does not mean that one can simply replace the
other, particularly because test conditions for one may not be
applicable to the other (refer to Section V.B for additional
discussion on this topic).
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Even though we cannot prescribe a single national approach for the
transition from RCRA permitting for air emissions, we can provide some
other recommendations to help permitting authorities and facility
owners or operators determine a sound approach. In this section, we
walk through some examples, intended as guidance, for transitioning
facilities that are in the process of obtaining or renewing a RCRA
permit. We hope that these examples will also enhance consistency among
the various regulatory agencies.
a. Example 1. Facility has submitted a RCRA permit renewal
application. Some sources, particularly hazardous waste incinerators,
have RCRA permits that are close to expiring. These sources may already
have initiated the renewal process by the time this rule is
promulgated. In these situations, we anticipate the source might need
to modify its current permit to accommodate any upgrades necessary to
comply with the new standards. Facilities may modify RCRA permits that
have been continued under Sec. 270.51 pending final disposition of the
renewal application. Thus, facilities will be able to use the
streamlined permit modification procedures that were promulgated in
Sec. 270.42(j) to effect the necessary changes pending resolution of
their renewal application. Depending on where they are in the renewal
process, the permitting authority may, alternatively, elect to fold the
modifications into the actual renewal process, thereby streamlining
some of the administrative requirements.
Issuance of RCRA hazardous waste combustor permits often takes
several years. If the source and the permitting authority are in the
early stages of renewal, the schedule of permitting activities may not
call for a trial burn to be conducted until sometime close to when the
source would be required to conduct comprehensive performance testing
under MACT. If so, the source may be able to either coordinate the
testing requirements of the two programs, e.g., if a RCRA risk burn is
necessary, or to perform just the comprehensive performance test under
MACT. If, on the other hand, they are further along in the renewal
process, the trial burn might be scheduled for the near future. In this
case, the approach outlined in Example 2 below might be more
appropriate to follow.
Regardless of the approach followed to transition the air emissions
and related operating parameters for the combustion unit to the Air
program, the
[[Page 52990]]
RCRA permit must still be renewed for all other aspects of hazardous
waste management at the facility.
b. Example 2. Permitting authority has approved, or is close to
approving, the RCRA trial burn plan at the time the final MACT
standards are promulgated. Both interim status facilities and those
seeking permit renewal are subject to requirements in Secs. 270.62 and
270.66 to develop and obtain approval for trial burn plans.
Requirements in these sections also call for permitting authorities to
provide public notice of approved (or tentatively approved) trial burn
plans and projected schedules for conducting the burns. We anticipate
that many of the hazardous waste combustors seeking permits who are
subject to this rulemaking will have already had their trial burn plans
approved, or close to being approved, by the time this rule is
promulgated. In such situations, we expect the facility to continue
with the trial burn as planned.
If the burn is successful, we anticipate the permitting authority
will issue a final RCRA permit that covers both the operations of the
hazardous waste combustor unit as well as all other hazardous waste
management activities at the site. We recommend that the permit be
worded flexibly to facilitate transition to title V once the source
subsequently demonstrates compliance with the MACT standards. For
example, conditions in the RCRA permit that would ultimately be covered
under title V might have associated sunset provisions indicating that
the conditions will cease to apply once the combustor unit demonstrates
compliance with the MACT standards. This would ensure that the amount
of time the source might be subject to emissions limits and operating
parameters under both RCRA and the CAA would be minimized. It would
also eliminate the need to engage in a separate permit modification
action to remove the conditions after the MACT compliance
demonstration.
Facilities in this scenario may determine they need to make some
changes to their equipment or operations to meet the new emissions
limits. These facilities will be able to use the streamlined permit
modification procedures that were promulgated in Sec. 270.42(i).
If the trial burn is not successful, we expect permitting
authorities to refer to the RCRA trial burn failure policy (see
Memorandum on Trial Burns, EPA530-F-94-023, July 1994). This policy
includes discussion in the following areas: (1) Taking immediate steps
to restrict operations; (2) initiating procedures for permit denial
(which would be appropriate for interim status or renewal candidates);
(3) initiating proceedings to terminate the permit (which would be
appropriate for proposed new facilities); and (4) authorizing trial
burn retesting after the facility investigates reasons for the failure
and makes changes to address them.
c. Example 3. The permitting authority does not anticipate
approving the trial burn plan, or the trial burn is not scheduled to
occur until after the Notice of Intent to Comply is submitted. As
suggested in the previous example, if a facility is ready to proceed
with a trial burn at the time the final hazardous waste combustor MACT
rule is promulgated, we expect that activities will proceed as planned.
Once the Notice of Intent to Comply is submitted, however, the
regulatory authority will have a better understanding of how and when
the facility intends to comply with the emissions standards, and how
the trial burn would fit in with the MACT compliance demonstration.
Thus, we expect the regulatory authority may wish to decide whether to
separately continue with the trial burn schedule laid out in the RCRA
permitting process or, conversely, coordinate with MACT comprehensive
performance testing, based on a number of considerations, including,
for example: (1) The facility's schedule and planned modifications for
MACT compliance; (2) progress on completing and approving the RCRA
trial burn plan; (3) whether the risk testing that may be necessary
under RCRA is likely to fit in with the MACT performance test schedule;
and (4) whether the facility wants to combine risk testing under RCRA
with the MACT performance test.
Even after a source conducts its comprehensive performance test and
subsequently submits the NOC to the regulatory agency, separate risk
testing might be necessary. For example, if the comprehensive
performance test did not generate sufficient data for a site-specific
risk assessment, a RCRA ``risk burn'' might be required (see discussion
in Part Five, Section V.B.).
E. What Is Meant by Certain Definitions?
When we considered incorporating MACT standards into both RCRA and
CAA regulations, we anticipated some confusion about definitions that
differ between the two programs. In the NPRM, we solicited comments on
our expressed preference not to reconcile these issues on a national
basis. (See 61 FR 17452). Several commenters suggest that EPA reconcile
the issues and clarify definitions. In the final rule, we have made
some changes, as discussed below, to ensure consistency of
interpretation and to minimize uncertainty for facilities seeking to
comply with today's rule. With these changes, we believe that revisions
to the definitions themselves are not necessary.
1. Prior Approval
In the proposed rule, we stated that RCRA and CAA are similar in
that they both require EPA prior approval before construction or
reconstruction of a facility. There were no adverse comments received
regarding this statement. The requirements for obtaining prior approval
are apparently clear under both programs.
We suggested in the proposed rule that readers of part 63 might be
unaware of their obligations under RCRA. Therefore, as proposed, we are
inserting the following note into Sec. 63.1206 Compliance Dates, ``An
owner or operator wishing to commence construction of a hazardous waste
incinerator or hazardous waste-burning equipment for a cement kiln or
lightweight aggregate kiln must first obtain some type of RCRA
authorization, whether it be a RCRA permit, a modification to an
existing RCRA permit, or a change under already existing interim
status. See 40 CFR part 270''. No adverse comments were submitted.
2. 50 Percent Benchmark
As stated in the proposed rule, RCRA and CAA both classify
``reconstruction'' as any modifications of a facility that cost more
than 50 percent of the replacement cost of the facility. However, the
significance of this term is different depending on which statute is
being applied. Two commenters confirmed that the distinction is
critical. Therefore, they concluded that, to avoid confusion, EPA
should defer to the CAA definition of ``reconstruction'' under RCRA
Section 1006(b) because it is the more flexible and appropriate
definition.
The primary concern about the 50 percent benchmark is in relation
to the limit imposed on RCRA interim status facilities for making
modifications. To ensure that this limit would not present a barrier to
making upgrades necessary to comply with MACT, we finalized a revision
to Sec. 270.72(b) to specify that interim status facilities can exceed
the 50 percent limit if necessary to comply with MACT. (See 63 FR
33829, June 19, 1998). Therefore, there is no potential for practical
conflict among the CAA and RCRA regulatory regimes, and no further
amendment or clarification is needed.
[[Page 52991]]
3. Facility Definition
As stated in the NPRM, the definition of ``facility'' differs
between CAA and RCRA. The definition has bearing in determining the
value of the facility with respect to the 50 percent rule on
modifications as discussed above. We proposed that the RCRA definition
should be used for the RCRA application to changes during interim
status, and the CAA definition should be used when determining
applicability of MACT standards to new versus existing sources.
Commenters disagreed with this approach and concluded that EPA should
defer to the CAA definition of facility because it encompasses the
entire operations at a site. We continue to believe that the CAA
definition should apply to CAA requirements and that the RCRA
definition should apply to RCRA requirements, since the definitions are
used for a different purpose under each statute. By clarifying the 50
percent benchmark issue for RCRA interim status facilities as discussed
above, we believe this satisfies commenters' concerns and, thus, it is
not necessary to reconcile the facility definition.
4. No New Eligibility for Interim Status
RCRA bestows interim status on facilities that were in existence on
November 19, 1980, or are in existence on the effective date of
statutory or regulatory changes that render the facility subject to
RCRA permitting requirements. The original RCRA rules for hazardous
waste incinerators and BIFs were finalized in 1980 and 1991,
respectively. Because these rules established the dates on which
incinerators and BIFs were first subject to RCRA permitting
requirements, the effective dates of those rules created the only
opportunity for interim status eligibility. The interim status windows
that occurred in 1980 and 1991 thus are not modified by this rule. The
lone exception is that facilities currently burning only nonhazardous
wastes that become newly listed or identified hazardous waste under
other future rules would still be able, under existing law, to qualify
for interim status (Sec. 270.42(g)).
5. What Constitutes Construction Requiring Approval?
The proposed rule noted that RCRA and CAA both have restrictions
requiring approval prior to construction, but that each statute defines
construction differently. We expressed our intent in the NPRM to retain
the two definitions. In the final rule, we continue to support
retaining the two definitions. Since most facilities currently possess
RCRA and CAA permits, these definitions are already being applied
concurrently with no apparent problems. Consequently, this is the most
practical and least confusing approach for permittees and regulators.
XII. State Authorization
A. What Is the Authority for Today's Rule?
Today's rule is being issued under the joint authority of the Clean
Air Act (CAA), 42 U.S.C. 7401 et seq., and the Resource Conservation
Recovery Act (RCRA), 42 U.S.C. 6924(o), 6924(q) and 6925. The new MACT
air emissions standards are located in 40 CFR part 63. Pursuant to
sections 1006(b) and 3004(a) of RCRA, 42 U.S.C. 6905(b) and 6924(a),
the MACT program will only be carried out under the CAA delegated
program. We strongly encourage States to adopt today's MACT standards
under their CAA statute and to apply for delegation under the CAA if
they do not have section 112 delegation. State implementation of the
MACT portions of this rule through its delegated CAA program will
facilitate coordination between the regulated entity and its State and
reduce duplicative permitting requirements under the CAA and RCRA.
In addition to promulgating the MACT standards, today's rule
modifies the RCRA program in other various respects and States
authorized for the RCRA base program must revise their programs
accordingly. For example, this rule revises the test for determining
whether a facility's waste retains the Bevill exclusion by adding
dioxins/furans to the list of constituents to be analyzed.
B. How Is the Program Delegated Under the Clean Air Act?
States can implement and enforce the new MACT standards through
their delegated 112(l) CAA program and/or by having title V authority.
A State's title V authority is independent of whether it has been
delegated section 112(l) of the CAA.
Section 112(l) of the CAA allows us to approve State rules or
programs to implement and enforce emission standards and other
requirements for air pollutants subject to section 112. Under this
authority, we developed delegation procedures and requirements located
at 40 CFR part 63, subpart EEE, for National Emission Standards for
Hazardous Air Pollutants (NESHAPS) under section 112 of the CAA (see 58
FR 62262, November 26, 1993, as amended, 61 FR 36295, July 10, 1996).
Similar authority for our approval of state operating permit programs
under title V of the CAA is located at 40 CFR part 70 (see 57 FR 32250,
July 21, 1992).
Submission of rules or programs by States under 40 CFR part 63
(section 112) is voluntary. Once a State receives approval from us for
a standard under section 112(l) of the CAA, the State is delegated the
authority to implement and enforce the part 63 standards under the
State's rules and regulations (the approved State standard would be
federally enforceable). States also may apply for a partial 112
program, such that the State is not required to adopt all rules
promulgated in 40 CFR part 63. We will implement the portions of the
112 program not delegated to the State. For example, documents such as
the NOC will be submitted to the Administrator when due, if the State
is not approved for the standards in today's rule.
Under 40 CFR 70.4(a) and section 502(d) of the CAA, States were
required to submit to the Administrator a proposed part 70 (title V)
permitting program by November 15, 1993. If a State did not receive our
approval by November 15, 1995 for its title V program, the title V
program had to be implemented by us in that State. As of today's rule,
all States have approved title V programs.\305\ This means that all
States have the authority to incorporate all MACT standards (changes to
section 112 of the CAA) into the title V permits as permit conditions,
and have the authority to enforce all the terms and conditions of the
title V permits. See 40 CFR 70.4(3)(vii).
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\305\ Under the CAA, Indian tribes may apply to EPA to be
treated as States and obtain approval of their own Clean Air Act
programs. Section 301(d) of the Clean Air Act, 42 U.S.C. 7601(d);
see also 40 CFR part 49. Tribes may thus become empowered to
implement the section 112 and title V portions of today's rule is
areas where they demonstrate jurisdiction and the capacity to do so.
Currently under RCRA, there is no Tribal authorization for the RCRA
Subtitle C hazardous waste program and thus EPA generally implements
the RCRA portions of today's rule in Indian Country.
EPA has authority to implement the federal operating permits
program 940 CFR part 71) where a State fails to adequately
administer and enforce an approved part 70 program, or where a State
fails to appropriately respond to an EPA objection to a part 70
permit. Additionally, some sources in U.S. Territories, the Outer
Continental Shelf, and Indian Country, are subject, or will soon be
subject, to part 71.
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The MACT standards are effective upon promulgation of this rule.
Facilities with a remaining permit term of three or more years will be
required to submit title V applications to their permitting authorities
to revise their permits.\306\ States will write the new
[[Page 52992]]
MACT standards into any new, renewed, or revised title V permit and
enforce all terms and conditions in the title V permit. A State's
authority to write and enforce title V permits is independent of its
authority to implement the changes to the MACT standards (changes to
section 112 of the CAA). Therefore, while both we and the State can
enforce the federal MACT standards within a title V permit, until the
State receives approval from us for required changes to section 112 of
the CAA, we will implement the 112 program.
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\306\ Title V permits are issued for a period not to exceed five
years. See 40 CFR 70.4(b)(3)(iii). You will have three years to come
into compliance with the new MACT standards. If you have fewer than
three years remaining on your title V permit term, our part 70
regulations do not require you to reopen and revise your permit to
incorporate the new MACT standard into the title V permit. See 40
CFR 70.7(f)(1)(i). However, the CAA does allow State programs to
require revisions to your permit to incorporate the new MACT
standard. Therefore, if you have fewer than three years remaining on
your title V permit, you should consult your state permitting
program regulations to determine whether a revision to your permit
is necessary to incorporate the new part 63 MACT standards. If your
are not required to revise your permit to incorporate the new
standard, you must still fully comply with today's standard.
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C. How Are States Authorized Under RCRA?
Under section 3006(g) of RCRA, enacted as part of the Hazardous and
Solid Waste Amendments (HSWA) of 1984, new requirements imposed by us
as a result of authorities provided by HSWA take effect in authorized
States at the same time as they do in unauthorized States--as long as
the new requirements are more stringent than the requirements a State
is authorized to implement. We implement these new requirements until
the State is authorized for them. After receiving authorization, the
State administers the program in lieu of the Federal government,
although we retain enforcement authority under sections 3008, 3013, and
7003 of RCRA.
Most of the new Federal RCRA requirements in today's final rule are
being promulgated through the HSWA amendments to RCRA. Regulatory
changes based on HSWA authorities are considered promulgated through
HSWA. The following RCRA sections, enacted as part of HSWA, apply to
today's rule: 3004(o) (changes to the MACT standards), 3004(q) (fuel
blending), and 3005 (omnibus). As a part of HSWA, these RCRA provisions
are federally enforceable in an authorized State until the necessary
changes to a State's authorization are approved by us. See RCRA section
3006, 42 U.S.C. 6926. The Agency is adding these requirements to Table
1 in Sec. 271.1(j), which identifies rulemakings that are promulgated
pursuant to HSWA.
In contrast, the change to the permit modification table (Appendix
I to Sec. 270.42) is promulgated through authorities provided to us
prior to HSWA. Therefore, this change does not become effective until
States adopt the revision and become authorized for that revision.
Under RCRA, States that have received authorization to implement
and enforce RCRA regulatory programs are required to review and, if
necessary, to modify their programs when we promulgate changes to the
federal standards that result in the new federal program being more
stringent or broader in scope than the existing federal standards. This
is because under section 3009 of RCRA, States are barred from
implementing requirements that are less stringent than the federal
program. See also 40 CFR 271.21.
In four respects, we consider today's final rule to be more
stringent than current federal RCRA requirements: (1) The added
definitions for dioxins/furans and TEQ (40 CFR 260.10); (2) the
requirement that permits for miscellaneous units must include
appropriate terms and conditions from part 63, subpart EEE standards
(40 CFR 264.601); (3) the establishment of new standards to control
particulate matter (40 CFR 266.105(c)); and (4) the addition of dioxin/
furans as listed potential Products of Incomplete Combustion (PIC) (40
CFR 266.112; Appendix VIII to 40 CFR part 266). Authorized States must
adopt these requirements as part of their State programs and apply to
us for approval of their program revisions. The procedures and
deadlines for State program revisions are set forth in 40 CFR 271.21.
Section 3009 of RCRA allows States to impose standards that are
more stringent or more extensive (i.e., broader) in scope than those in
the Federal program (see also 40 CFR 271.1(i)(1)). Thus, for those
Federal changes that are less stringent, or reduce the scope of the
Federal program, States are not required to modify their programs.
Further, EPA will not implement those provisions promulgated under HSWA
authority that are not more stringent than the previous federal
regulations in States that have been authorized for those previous
federal provisions. EPA will implement these new provisions in States
that are not authorized to implement the previous federal regulations.
In two respects, we consider today's rule to be less stringent than
current federal requirements: (1) The inapplicability of certain
provisions of RCRA once specified part 63, subpart EEE and other
requirements have been met (40 CFR 264.340(b)(1); 265.340(b)(1);
266.100(b)(1), 266.100(d)(1) and (d)(3); 266.100(h); 270.19; 270.22;
270.62; and 270.66); and (2) the provision for RCRA permit
modifications to remove inapplicable RCRA conditions (Appendix I to 40
CFR part 270.42).\307\
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\307\ States choosing to adopt the other less stringent changes
to RCRA in today's rule also should adopt the change to 40 CFR
270.42. The change to 40 CFR 270.42 provides the RCRA permit
modification procedure to eliminate inapplicable RCRA requirements
once specified part 63, subpart EEE and other requirements have been
met.
---------------------------------------------------------------------------
The rest of the requirements in today's rule, in our view, are
neither more nor less stringent than current regulatory requirements.
They are either reiterations or clarifications of our existing
regulations or policies (40 CFR 264.340(b)(2), 265.340(b)(2),
266.100(b)(2), and 266.101).
Although States must adopt only those requirements that are more
stringent, in the spirit of RCRA section 1006(b), which directs us to
avoid duplicative RCRA and CAA requirements, we strongly urge States to
adopt all aspects of today's final rule (including the clarifying as
well as less stringent sections). The adoption of all portions of
today's final rule by state agencies will ensure clear, consistent
requirements for owners, operators, affected sources, State regulators,
and the public. Pursuant to today's rule, the permitting requirements
will be implemented solely through the CAA title V program. If a RCRA
permitted facility is required to use RCRA risk-based air emissions
standards in addition to the CAA designated technology based standards,
we will exercise our omnibus authority in section 3005 of RCRA to
modify the facility's RCRA permit.\308\ Therefore, we believe that the
standards promulgated today properly implement the goals of sections
3004(o) and (q) of RCRA to ensure the safe and proper management of the
affected combustion units and the goal of section 1006(b) of RCRA to
avoid duplicative and potentially confusing permitting requirements
under two different environmental statutes (RCRA and CAA). For these
reasons, we encourage States to adopt these
[[Page 52993]]
regulations as quickly as their legislative and regulatory processes
will allow.
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\308\ If a State has a provision in its State air statute or
regulation that is equivalent to the RCRA omnibus authority (RCRA
section 3005(c)), we expect that the State will be able to use its
air authority in pace of its RCRA omnibus authority.
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Part Six: Miscellaneous Provisions and Issues
I. Does the Waiver of the Particulate Matter Standard or the
Destruction and Removal Efficiency Standard Under the Low Risk Waste
Exemption of the BIF Rule Apply?
Section 266.109 of the current BIF regulation provides a
conditional exemption from the destruction and removal efficiency
standard and the particulate matter standard for low risk wastes. We
proposed to restrict eligibility for the waiver of the particulate
matter standard to BIFs other than cement and lightweight aggregate
kilns because the waiver could supersede the MACT requirements for the
particulate matter standards. We had the same concern for the
destruction and removal efficiency requirements. See 61 FR at 17470.
After reconsidering the issue, we are clarifying that today's MACT
requirements are separately applicable and enforceable and that no
action is needed to ensure that a BIF waiver does not supersede the
MACT requirements. See the discussions in Part Five of today's preamble
regarding integration of the MACT and RCRA standards.
II. What Is the Status of the ``Low Risk Waste'' Exemption?
Section 264.340(b) and (c) exempts certain incinerators from the
RCRA emission standards if the hazardous waste burned contains (or
could reasonably be expected to contain) insignificant concentrations
of Appendix VIII, part 261, hazardous constituents. We proposed that
this ``low risk waste'' provision no longer be applicable incinerators
on the MACT compliance date because a risk-based exemption from
technology-based MACT standards seemed inappropriate. See 61 FR at
17470. After reconsidering the issue, we have determined that no
specific action is necessary because the MACT standards are separately
applicable and enforceable standards. See the discussion in Part Five
of today's preamble regarding integration of the MACT and RCRA
standards.
III. What Concerns Have Been Considered for Shakedown?
In the proposal, we expressed concern that some new units do not
effectively use their allotted 720-hour pre-trial burn shakedown period
or appropriate extensions to correct operational problems. This can
potentially lead to trial burn failures and emission exceedances, which
pose unnecessary risks to human health and the environment. Therefore,
we proposed three shakedown options to enhance regulatory control over
trial burn testing:
(1) Prior to scheduling trial burns, we would require facilities to
provide the Director a minimum showing of operational readiness.
(2) We would require notification of operational readiness prior
to, and following, the shakedown period.
(3) We would provide guidance on how to effectively prepare for a
trial burn. These options were proposed for inclusion under both the
CAA and RCRA regulations, and comments were requested regarding their
usefulness.
A few commenters preferred Option 3 because it would be useful in
determining how to effectively prepare for a trial burn. Regarding
Options 1 and 2, two commenters felt the cost, time, and resources
required for a trial burn already provide adequate financial incentive
to prepare, plan, and conduct trial burns efficiently. Two commenters
felt that Option 3 provided the potential for inequities in
implementation of the guidance by the permit writer. In general, most
commenters agreed that additional regulatory requirements are not
necessary.
In light of the comments, we decided not to adopt any of the
proposed options. We acknowledge that it is in the facility's best
interest to conduct a successful trial burn that most facilities will
properly utilize their shakedown period. However, during the transition
period from RCRA to MACT compliance, we strongly encourage facilities
to properly use their shakedown period to correct operational problems
that pose unnecessary risks to human health and the environment.
Therefore, with the exception of risk burns, we are pursuing the
deferral of RCRA trial burns to the MACT performance test requirements.
A source remains subject to RCRA trial burns during the transition
period to MACT compliance. For facilities where unique considerations
make a SSRA necessary, risk-based permit conditions may result. In such
cases, there likely would need to be conditions for all phases of
operation in the RCRA permit. Thus, start-up and shakedown would still
be an issue for some RCRA combustor facilities given that they would
have to be in compliance with the unique RCRA emission standards even
during startup and shakedown (unless the permit conditions specify
otherwise).
IV. What Are the Management Requirements Prior to Burning?
Today, we are finalizing the proposal to revise 40 CFR 266.101
(``Management prior to burning'') to clarify that fuel blending
activities are regulated under RCRA. See 61 FR at 17474 (April 19,
1996). As described in detail in the proposal, this is already implicit
(and for some units, explicit) in existing rules. Therefore, today's
rule is more an interpretive clarification. See 52 FR 11820 (April 13,
1987). By incorporating the term ``treatment'' into the regulation, we
are clarifying that fuel blending activities that are conducted in
units other than 90-day tanks or containers also are subject to
regulation.
We received two comments expressing concern that this would subject
all fuel blending-related equipment permitting, without allowing for
case-by-case determinations. For example, these commenters believe that
some pre-processing activities conducted by blenders (shredding, drum
crushing, and other physical handling) do not meet the definition of
treatment and should not be subject to permitting standards. However,
we feel that these activities meet the existing definition of
treatment. They are ``processe(s) . . . designed to change the physical
. . . composition of . . . hazardous waste so as to . . . render such
waste amenable for recovery'' via combustion. See 40 CFR 260.10
(definition of ``treatment'').
Moreover, these pre-processing activities should be subject to
permitting requirements. Controls on these activities are necessary to
protect against releases of hazardous constituents to the environment
due to the nature of those operations (e.g., crushing or shredding of
drums containing hazardous wastes, grinding of waste materials, etc.).
See Shell Oil v. EPA, 950 F. 2d 741, 753-56 (D.C. Cir. 1991), which
broadly construes the definition of treatment to assure that the RCRA
goal of cradle-to-grave management of hazardous wastes is satisfied and
that specific types of units remain subject to subtitle C regulation.
For units that do not already meet the definition of a specific unit,
subpart X is available to provide the appropriate standards.
V. Are There Any Conforming Changes to Subpart X?
In today's rule, we are making a conforming change to part 264
subpart X (Sec. 264.601) to make reference to part 63 subpart EEE.
Hazardous waste treatment, storage, and disposal facilities that
are not
[[Page 52994]]
classified under other categories (e.g., tank systems, surface
impoundments, waste piles, incinerators, etc.) are classified as
miscellaneous units and regulated under part 264 subpart X. However,
due to the varying types and designs of miscellaneous units, subpart X
does not include specific performance standards. Instead, subpart X
makes reference to requirements in other sections of the regulations.
Section 264.601 of subpart X states that ``Permit terms and provisions
shall include those requirements of subparts I through O and subparts
AA through CC of this part, part 270, and part 146 that are appropriate
for the miscellaneous unit being permitted .'' This statement directs
the permitting agency to look at the requirements (e.g., performance
standards, operating parameters, monitoring requirements, etc.) from
other sections in the regulations when developing appropriate permit
conditions for miscellaneous units.
In the past, permitting authorities have often looked to the part
264 subpart O regulations for incinerators to develop the appropriate
permit conditions for units such as thermal desorbers and carbon
regeneration units. Since today's rule upgrades the air emission
standards for certain source categories, these new standards also
should be considered when determining the appropriate requirements for
miscellaneous units, most notably those engaged in any type of thermal
operation. Therefore, the language in Sec. 264.601 of subpart X is
being modified to incorporate a reference to part 63 subpart EEE.
VI. What Are the Requirements for Bevill Residues?
A. Dioxin Testing of Bevill Residues
In the proposal, we proposed to add polychlorinated dibenzo-p-
dioxin and polychlorinated dibenzo-furan compounds to appendix VIII of
part 266. Appendix VIII lists those compounds that may be generated as
products of incomplete combustion and that must be included in testing
of Bevill residues conducted pursuant to 40 CFR 266.112. Products of
incomplete combustion can be unburned organic compounds that were
originally present in the waste, thermal decomposition products
resulting from organic constituents in the waste, or compounds
synthesized during or immediately after combustion. We noted in the
proposal that there is a considerable body of evidence to show that
dioxin and furan compounds can be formed in the post-combustion regions
of hazardous waste burning boilers, industrial furnaces, and
incinerators, especially at temperatures between 250-450 deg.C.\309\
\310\ Collected particulate matter in the post-combustion regions of
furnaces can provide sites for adsorption of precursors, formation of
dioxins and furans by surface chlorination of precursors, catalytic
production of chlorine for subsequent chlorination of dioxin and furan
precursors, and de novo synthesis of dioxins and furans. This same
particulate matter may be subsequently managed as excluded Bevill
residue.
---------------------------------------------------------------------------
\309\ USEPA, ``Estimating Exposure to Dioxin-Like Compounds'',
EPA/600/6-88/005Ca, June 1994.
\310\ USEPA, ``Combustion Emissions Technical Resource Document
(CETRED)''. EPA/530/R-94/014, May 1994.
---------------------------------------------------------------------------
No evidence was provided by commenters to show that dioxins and
furans cannot be formed in cooler, post-combustion regions of furnaces
(e.g., ductwork, boiler tubes, heat exchange surfaces, and air
pollution control devices). A few commenters referenced the total
number of nondetects for all of the compounds in the cement kiln dust
database. However, the relevance of this information specifically to
dioxins and furans was unclear. Dioxins and furans have repeatedly been
detected in cement kiln dust, as well as other Bevill residues.\311\
\312\
---------------------------------------------------------------------------
\311\ USEPA, ``Report to Congress on Cement Kiln Dust'', EPA/
530/R-94/001, December 1993.
\312\ USEPA, ``Dioxins/Furans, Metals, Chlorine, Hydrochloric
acid, and Related Testing at a Hazardous Waste-Burning Light-Weight
Aggregate Kiln'', June 1997 Draft Report.
---------------------------------------------------------------------------
The majority of commenters were concerned about implementation
issues. Many felt that the addition of dioxins and furans to part 266
appendix VIII, in conjunction with the proposed requirement for daily
sampling and analysis of Bevill residues, would make Bevill
demonstrations prohibitively expensive. They also noted that the
turnaround time for daily dioxin and furan analyses would delay
compliance demonstrations and result in shortages in storage capacity.
One commenter felt that daily sampling for dioxins and furans is not
warranted because cement kiln dust at their site has already been shown
to meet the proposed Bevill exclusion criteria for dioxins and furans.
None of these arguments directly address our basic premise that dioxin
and furan compounds can be generated in combustion systems, are of
concern to the protection of human health and the environment, and, as
such, should be included in part 266 appendix VIII. Rather, these
comments pertain to issues that are more readily and appropriately
resolved within the context of site-specific Bevill testing plans.
The proposed daily residue test frequency, which was cited most
often as an impediment in conjunction with dioxin and furan analysis,
is not being promulgated as part of today's rule. The rule will leave
maximum flexibility for development of appropriate dioxin and furan
analysis frequencies considering site-specific factors. Most facilities
should be able to substantially limit the number of dioxin and furan
analyses after an initial sampling effort. Most residue test plans rely
on the concentration-based comparisons to F039 nonwastewater levels (40
CFR 266.112(b)(2)) in combination with a phased testing approach. Under
the phased approach, test frequency can be substantially reduced for
those constituents where initial sampling efforts reveal that
concentrations are well below the F039 levels. Of the facilities where
residue testing for dioxins and furans has been performed, we are aware
of only two facilities where dioxins and furans have exceeded the F039
levels. Thus, the burden of higher analytical costs is expected to be
appropriately limited to those few sites with significant dioxin and
furan residue concentrations.
Several commenters pointed out that some Bevill residues (e.g.,
slag from primary smelters) are generated prior to the post-combustion
regions typically associated with dioxin and furan formation. Indeed,
the preamble discussion in the proposal focused exclusively on post-
combustion residues and did not address Bevill-exempt primary smelter
slags. We currently do not have analytical data on dioxins and furans
in smelter slag. However, our current information on dioxin and furan
formation mechanisms suggests that it would be highly unlikely to
expect significant dioxins and furans in smelter slag. Therefore, we
agree that dioxin and furan analyses should be limited to those
residues where there is a reasonable expectation that dioxins and
furans could be present (e.g., post-combustion residues).
Finally, two commenters disagreed with our assertion that dioxins
and furans have been shown, in a national comparison, to be higher in
residues from hazardous waste burning cement kilns than from other
cement kilns. Although this information was included in the proposal as
background, it is not necessary to reconcile various interpretations
regarding national trends for today's rule. The 40 CFR 266.112
provisions are site-specific, and 40 CFR 266.112(b)(1) provides ample
opportunity for you to demonstrate, on a site-specific basis as
necessary, that waste-derived residues are not
[[Page 52995]]
significantly different from normal residues.
After considering all of the comments on the proposal, we are
adding dioxins and furans to part 266 appendix VIII in today's rule. A
notation has been included to clarify that dioxin and furan analyses
are required only for post-combustion residues. Commenters provided no
compelling information to challenge the classification of dioxins and
furans as products of incomplete combustion which can be formed in
post-combustion regions of combustion systems, and the presence of
dioxin and furan compounds in several post-combustion Bevill residues
is clearly documented. Also, the increased use of carbon injection
technology to achieve dioxin and furan stack emissions reductions could
increase dioxin and furan contamination of Bevill residues in the
future. The addition of dioxins and furans to part 266 appendix VIII is
not expected to unduly burden the regulated community because
facilities with dioxins and furans well below exclusion levels should
be able to justify a minimum test frequency.
Dioxins and furans will be listed in part 266 appendix VIII simply
as ``Polychlorinated dibenzo-p-dioxins'' and ``Polychlorinated dibenzo-
furans''. However, the specific form of dioxins and furans that must be
determined analytically will depend on the portion of the two-part test
that is being implemented. If you are performing a comparison with
normal residues pursuant to 40 CFR 266.112(b)(1), specific congeners
and homologues must be measured and converted to TEQ values using the
procedure provided in part 266, appendix IX, section 4.0. We received
no comments regarding this portion of the proposal. If you are
utilizing the concentration-based comparison to the F039 nonwastewater
levels in 40 CFR 268.43 as outlined in 40 CFR 266.112(b)(2), then only
the tetra-, penta-, and hexa-homologues need to be measured (these are
the only homologues with established F039 concentration limits). One
commenter seemed uncertain as to whether the tetra-, penta-, and hexa-
homologue concentrations should be converted to TEQ values. We have
revised the regulatory language to clarify that total concentrations
for each homologue, not TEQs, should be used for the F039 comparisons.
Another commenter objected to the use of F039 levels for the health-
based comparison, noting that the F039 concentrations are technology-
based levels. Our rationale for relying on the F039 concentrations has
been explained previously (see 58 FR at 59598, November 9, 1993) and is
not being revisited in today's rule.
B. Applicability of Part 266 Appendix VIII Products of Incomplete
Combustion List
In the proposal, we noted the confusion regarding whether every
constituent listed on the part 266 appendix VIII list must be included
in residue testing at every facility. We proposed to clarify that the
part 266 appendix VIII list is applicable in its entirety to every
facility.
The only comments received on this issue were objections to our
characterization of this change as a clarification. The commenters felt
this was a substantive change that should not be enforced prior to the
effective date of any final rule establishing the revision as law. The
Agency is proceeding in today's rule to make the part 266 appendix VIII
list applicable in its entirety to every facility by changing the title
of the appendix from ``Potential PICs for Determination of Exclusion of
Waste-Derived Residues'' to ``Organic Compounds for Which Residues Must
Be Analyzed.'' This change is considered a revision to the part 266
regulations effective 30 days after the date of publication of today's
rule. We will not seek to retroactively enforce this provision.
VII. Have There Been Any Changes in Reporting Requirements for
Secondary Lead Smelters?
We proposed that secondary lead smelters subject to MACT standards
for the secondary lead source category not be subject to RCRA air
emission standards. 61 FR at 17474 (April 19, 1996). This exemption
would apply only if a secondary lead smelter processed the type of feed
material we evaluated in promulgating the secondary lead MACT
standards, namely, lead-bearing hazardous wastes containing less than
500 ppm toxic nonmetals and/or hazardous wastes listed in appendix XI
to 40 CFR part 266. Id. at 14475. Secondary lead smelters are presently
not subject to RCRA air emission standards under these circumstances.
See existing Sec. 266.100 (c)(1) and (c)(3). However, they are subject
to certain notification and recordkeeping requirements found in
Sec. 266.100 (c)(1)(I) and (c) (3) and on-going sampling and analysis
requirements in Sec. 266.100 (c)(1)(ii) and Sec. 266.100 (c)(3)(i)(D).
The practical effect of the proposal was to continue to relieve
secondary lead smelters of these administrative requirements.
The proposal was supported by the public commenters. The reason for
the proposal remains. That is, now that secondary lead smelters are
complying with MACT standards for their source category, it is not
necessary for them to be regulated under RCRA also for their air
emissions. 60 FR 29750 (June 23, 1995). For the same reason, it is
unnecessary to have the same level of recordkeeping and other
administrative oversight as when these units were exempt from RCRA air
emission requirements but not yet complying with CAA standards for
hazardous air pollutants. 61 FR at 14474. Consequently, we are
finalizing this portion of the proposal.
Today's rule takes the form of an amendment to the RCRA BIF rule
(new Sec. 266.100 (h)) and indicates that secondary lead smelters are
exempt from all provisions of the BIF rule except for Sec. 266.101,
which contains the restrictions on types of hazardous waste which may
be burned, as described in the first paragraph above. As proposed, a
secondary lead smelter must provide a one-time notice to the Regional
Administrator or State Director identifying each hazardous waste burned
and stating that the facility claims an exemption from other
requirements in the BIF rules. Those secondary lead smelters which have
already notified pursuant to existing regulatory provisions (namely
Sec. 266.100 (c) (1) (i) or Sec. 266.100 (c) (3) (i) (D)) would not
have to renotify.
VIII. What Are the Operator Training and Certification Requirements?
Section 129 of the CAA requires us to develop and promulgate a
program for training and certification of operators of facilities that
burn municipal and medical wastes. We accordingly promulgated operator
training and certification requirements for the operators of municipal
waste combustors (60 FR 65424 (December 19, 1995)) and medical waste
incinerators (62 FR 48348 (September 15, 1997)). At proposal, we
considered similar requirements for hazardous waste combustor operators
also and requested comments on whether: (1) Operator certification
requirements are necessary for hazardous waste combustors, and (2) the
American Society of Mechanical Engineers (ASME) standards (or an
equivalent state certification program) are appropriate and sufficient.
We note that ASME has established a Standard for the Qualification and
Certification of Hazardous Waste Incinerator Operators in collaboration
with the American National Standards Institute (ASME Standard Number
QHO-1-1994) and has been providing certifications since 1996.
[[Page 52996]]
Commenters differed widely on two key issues: (1) Whether such a
training program should be voluntary, mandatory, or even necessary,
considering that RCRA already requires some site-specific training
program (40 CFR 264.16); and (2) whether the certifying agency should
be an independent body like ASME versus an industry organization like
the Cement Kiln Recycling Coalition. Most commenters favored the
establishment of a mandatory operator certification program by an
independent organization that develops consensus standards (e.g., ASME,
American Society for Testing and Materials, or American National
Standards Institute) in order to preserve the integrity of
certification. We agree and note that ASME has already done commendable
work in developing certification programs for operators of municipal
waste combustors, medical waste incinerators, high capacity fossil-fuel
fired plants, and hazardous waste incinerators. Each combustor program
includes defined criteria for certification, including operator
qualifications, recommended training, examination content, minimum
passing grades, and due process. These programs are incorporated (at
least in part) into EPA's combustion regulations to satisfy the CAA
section 129 mandate, and we are extending similar requirements in
today's rule to all hazardous waste combustor operators also. We find
that the concerns about good operator training and certification that
underlie the section 129 requirement for municipal waste combustors and
medical waste incinerators apply as well to those persons charged with
the responsibility for safe handling and burning of hazardous waste.
Some kiln operators and the Cement Kiln Recycling Coalition have
commented that cement and lightweight aggregate kilns are much larger
and more diverse facilities than most hazardous waste incinerators,
that these kilns operate with employee unions that object to additional
outside certification when site-specific training programs are already
in place, and that the ASME certification programs are not pertinent or
applicable to them. We recognize that there are some differences in the
operation of incinerators and cement and lightweight aggregate kilns.
However, these differences do not suggest that operator training and
certification should be abandoned. Rather, they serve to emphasize the
importance of having a rigorous operator training and certification
program in place and having it subject to regulatory agency scrutiny.
In that regard, we are aware of the Cement Kiln Recycling Coalition's
efforts to develop a suitable industry-wide training and certification
program for the kilns. However, the Cement Kiln Recycling Coalition's
efforts to date have not resulted in a final industry-wide set of
standards that can be relied upon in today's rule, and we note that the
current general facility training programs under Sec. 264.16 do not
fully cover the areas that would need to be addressed at facilities
burning hazardous waste. For example, Sec. 264.16 neither identifies
important areas of training with respect to daily operations (such as
hazardous waste and residues handling operations, air pollution control
device operations, troubleshooting, normal start-up and shut-down
procedures, continuous emissions monitoring system operation and
maintenance etc.) nor discriminates among the different categories of
operators. Also, Sec. 264.16 does not specify any operator
certification nor minimum standards for certification, which are needed
to ensure the initial and continual competence of the hazardous waste
combustor facility operators.
We expect that kiln specific programs will be developed in the near
future after complete analysis for consistency, reliability and
conformance with principles of good operating and operator practices
(including training and certification). Today's rule therefore
specifies that each hazardous waste combustor facility must develop an
operator training and certification program. In the case of cement and
lightweight aggregate kilns, the facility must submit its program to
the Agency for approval. The submittal will be evaluated for
completeness, reliability and conformance with appropriate principles
of good operator and operating practices (including training and
certification). If a state-approved certification program becomes
available, the facility's program must conform to that state program.
These are to ensure that sufficient specifics are included in each
facility program. In the case of hazardous waste incinerators, the
facility's program must conform to either a state-approved
certification program or, if none exists, to the ASME certification
program (Standard No. QHO-1-1994). Again, this is to ensure that
sufficient specifics are contained in a facility program.
IX. Why Did the Agency Redesignate Existing Regulations Pertaining to
the Notification of Intent To Comply and Extension of the Compliance
Date?
In today's final rule, we redesignate existing regulations
pertaining to the Notification of Intent to Comply with subpart EEE and
extensions of the compliance date to install pollution prevention or
waste minimization controls to meld them into the new provisions of the
subpart. This ensures that similar topics (e.g., notifications,
compliance requirements) are grouped together in the rule. We also
revise those existing regulations to: (1) Convert the regulatory
language to plain language consistent with the new provisions; (2)
include references to the new provisions; and (3) include references to
the actual effective date of the rule.
We promulgated these regulations as Part 1 of revised standards for
hazardous waste combustors. See 63 FR 33782 (June 19, 1998). We are
promulgating part 2 today, which comprises the emission standards and
compliance requirements. Today's revisions to the existing standards
does not constitute a repromulgation and does not reopen the comment
period for those standards.
We are redesignating the existing regulations as indicated in the
following table:
----------------------------------------------------------------------------------------------------------------
Existing regulation Topic Predesignated regulation
----------------------------------------------------------------------------------------------------------------
Sec. 63.1211(a) and (b)............... Notification requirements for Sec. 63.1210(b) and (c)
the notification of intent to
comply.
Sec. 63.1211(c)....................... Requirements for sources that Sec. 63.1206(a)(2)
do not intend to comply.
Sec. 63.1212.......................... Progress report requirements Sec. 63.1211(b)
for the notification of
intent to comply.
Sec. 63.1213.......................... Certification that must Sec. 63.1212(a)
accompany the notice of
intent to comply.
Sec. 63.1214.......................... Extension of the compliance Sec. 63.1206(a)(1)
date.
Sec. 63.1215.......................... Requirements for sources that Sec. 63.1212(b)
become affected sources after
the effective date of the
emission standards.
[[Page 52997]]
Sec. 63.1216.......................... Extension of the compliance Sec. 63.1213
date to install pollution
prevention or waste
minimization controls.
----------------------------------------------------------------------------------------------------------------
Part Seven: National Assessment of Exposures and Risks
We received many public comments on the risk assessment for the
proposed rule.313 In addition, the risk assessment was peer
reviewed in accordance with EPA guidelines. Many of the commenters
commented on similar topics. These topics included the
representativeness of the HWC facilities modeled, the estimation of
facility emissions, the exposure scenarios evaluated, and the
assessment of risks from mercury. As of result of these comments, we
made significant changes in the risk assessment for the final rule.
Also, new information became available after proposal on food intake
rates for home-produced foods and methods for assessing exposures to
mercury. In addition, EPA issued guidance for use of probabilistic
techniques in risk assessments and a policy for evaluating risks to
children. These were also considered in making revisions to the risk
assessment. A complete discussion of the risk assessment for today's
rule may be found in the background document.314
---------------------------------------------------------------------------
\313\ ``Risk Assessment Support to the Development of Technical
Standards for Emissions from Combustion Units Burning Hazardous
Wastes: Background Information Document,'' February, 1996.
\314\ See the background document, ``Human Health and Ecological
Risk Assessment Support to the Development of Technical Standards
for Emissions from Combustion Units Burning Hazardous Wastes:
Background Document--Final Report,'' July, 1999.
---------------------------------------------------------------------------
I. What Changes Were Made to the Risk Methodology?
A. How Were Facilities Selected for Analysis?
The representativeness of the example facilities used in the risk
assessment at proposal was widely questioned by commenters. We analyzed
eleven example facilities for the proposed rule: two commercial
incinerators, two on-site incinerators, two lightweight aggregate
kilns, and five cement kilns.315 While these facilities
represented a geographically diverse set of facilities in each source
category, it was not possible to demonstrate in any formal way that the
facilities were representative of the universe of facilities covered by
the rule.
---------------------------------------------------------------------------
\315\ See 61 FR 17370 and ``Risk Assessment Support to the
Development of Technical Standards for Emissions from Combustion
Units Burning Hazardous Wastes: Background Information Document''
(February, 1996).
---------------------------------------------------------------------------
Because of this difficulty, we concluded that the most efficient
approach for assuring the representativeness of the facilities analyzed
was to select a stratified random sample. The number of strata was
determined by the number of categories and subcategories of sources for
which risk information was desired. The final sample of facilities
chosen for analysis includes 66 randomly selected facilities and 10 of
the 11 facilities selected at proposal for a total sample of 76
facilities out of a universe of 165 facilities within the contiguous
United States.316 The sample sizes are as follows:
---------------------------------------------------------------------------
\316\ A large on-site incinerator analyzed at proposal that is
undergoing RCRA closure was excluded from the analysis.
Hazardous Waste Combustion Facility Stratum and Sample Sizes
----------------------------------------------------------------------------------------------------------------
High end
Combustion facility category Stratum size Random sample NPRM sample Final sample sampling
size size size probability
--------------------------------------------------------------------------------------------------------\1\-----
Cement Kilns.................... 18 10 5 15 98
Lightweight Aggregate Kilns..... 5 3 2 5 100
Commercial Incinerators:
Including Waste Heat Boilers 20 11 2 13 97
Excluding Waste Heat Boilers 12 7 2 9 95
Large On-Site Incinerators:
Including Waste Heat Boilers 43 17 1 18 94
Excluding Waste Heat Boilers 36 15 0 15 90
Small On-Site Incinerators:
Including Waste Heat Boilers 79 25 0 25 96
Excluding Waste Heat Boilers 65 16 0 16 88
Incinerators With Waste Heat 29 15 1 16 92
Boilers........................
----------------------------------------------------------------------------------------------------------------
\1\ Probability that a facility that lies in the upper 10% of the distribution of risk will be sampled.
For the randomly selected facilities, sample sizes within a given
category were chosen such that the probability of sampling a facility
in the upper ten percent of the distribution of risk would be 90
percent or greater. The probabilities actually achieved range from 88
to 100 percent depending on the size of the original, non-randomly
chosen sample and changes in the sampling frame that occurred during
the random sampling process.317
---------------------------------------------------------------------------
\317\ Changes in the sampling frame occurred as a result of
facilities that were missing from the original sampling frame were
misclassified, or were no longer burning hazardous waste and had
begun RCRA closure.
---------------------------------------------------------------------------
We did not target area sources specifically for sampling because
the statutory definition of major sources versus area sources is based
on facility-wide emissions of hazardous air pollutants and such
information was not available at the time the sampling was performed.
Therefore, it was not possible to determine the sampling frame. We
expect that on-site incinerators, both large and small, at large
industrial facilities are major sources rather than area sources.
Because area sources are of interest, we made risk inferences based on
those area source incinerators that could be identified and had
otherwise been
[[Page 52998]]
sampled.318 For cement kilns, all area sources were sampled
and used for making such inferences.
---------------------------------------------------------------------------
\318\ Area source incinerators that were identified included
commercial incinerators and on-site incinerators at U.S. Department
of Defense installations.
---------------------------------------------------------------------------
B. How Were Facility Emissions Estimated?
At proposal, we estimated baseline emissions (reflecting current
conditions) for the example facilities from the distribution of stack
gas concentrations for the corresponding category of sources. Both
central tendency and high end emissions estimates were made based on
the 50th and 90th percentiles of the stack gas concentration
distributions. For the purpose of evaluating risks associated with the
proposal, we assumed that facilities emitted at the design level
determined to be necessary to meet the standard, even if this meant an
increase in emissions over baseline. Many commenters thought that using
percentiles to estimate emissions was inappropriate and that site-
specific emissions should be used instead. Commenters also thought that
it was incorrect to project an increase in risk with the proposed
standards (which occurred as a result of allowing emissions to increase
over baseline). We agree with these comments. For the final rule, we
estimated emissions based on site-specific stack gas emission
concentrations and flow rates. Site-specific stack gas concentration
data were used where emissions measurements were available; otherwise,
stack gas concentrations were imputed. For today's rule, we assumed
emissions would remain unchanged from baseline in instances where a
facility's emissions are already below the design level (which is taken
as 70 percent of the MACT standard).319 In instances where a
facility's emissions exceed the design level, we determined the
percentage reduction in emissions required to meet the design level. We
then applied this reduction to each chemical constituent to which the
standard applies.
---------------------------------------------------------------------------
\319\ This is also consistent with the assumption made in the
cost and economic analysis that facilities that are currently
emitting below the design level will not need to retrofit using new
control technology.
---------------------------------------------------------------------------
The imputation approach we used in instances where measured data
were not available involves the random selection of emissions
concentrations from a pool of emissions concentrations for other
facilities and test conditions that are believed to be reasonably
representative of the facility in question. For groups of interrelated
constituents (e.g., different dioxin congeners or mercury species),
imputation was carried out for the group of interrelated constituents
taken together rather than each individual constituent separately. We
used the random imputation approach to preserve the variability in
emissions exhibited by the pooled data. Another commonly used approach
for estimating emissions, emissions factors, generally represents
average conditions and does not reflect the variability in emissions
across facilities in a given source category. Because the objective of
the risk assessment is to characterize the distribution of risks across
a given source category, we deemed the use of average emissions to be
inappropriate except where only very limited data are available (i.e.,
for cobalt, copper, and manganese). Although the random imputation
approach may significantly over or under estimate emissions for a given
facility (a problem also inherent in emission factors), we expect that
the distributions of risk across a given source category are better
characterized using random imputation than with an emissions factor
approach or any other approach that does not account for the variation
in emissions from one facility to the next.
Emissions estimates were made for all chemical constituents covered
by the rule for which sufficient data were available, including all
2,3,7,8-chlorine substituted dibenzo(p)dioxins and dibenzofurans,
elemental mercury (Hg0), divalent mercury (Hg+2),
lead, cadmium, arsenic, beryllium, trivalent chromium
(Cr+3), hexavalent chromium (Cr+6), chlorine, and
hydrogen chloride. In addition, emissions estimates were made for
particulate matter (PM10 and PM2.5) and nine
other metals, three of which (cobalt, copper, and manganese) were not
assessed at proposal but were included in the risk assessment for the
final rule. Chemical-specific emissions estimates could not be made for
organic constituents other than dioxins and furans (e.g., various
products of incomplete combustion) due to the lack of sufficient
emission measurements. We assessed the risks from all constituents for
which chemical-specific emissions estimates could be made, as well as
from particulate matter. A complete discussion of the emissions
estimates used in the risk assessment may be found in the technical
support documents for today's rule.320
---------------------------------------------------------------------------
\320\ See ``Final technical Support Document for HWC MACT
Standards, Volume V: Emission Estimates and Engineering Costs.''
July, 1999.
---------------------------------------------------------------------------
C. What Receptor Populations Were Evaluated?
The risk assessment at proposal examined risks to individuals
engaged in subsistence activities such as farming and fishing. Some
commenters viewed these types of activities as unlikely to occur and
questioned whether these types of exposures are representative of
actual exposures and risk. Other commenters thought the exposure
pathways included in the analysis did not fully reflect potential
exposures to individuals living a true subsistence lifestyle. We share
the concerns raised by commenters and have refocused the assessment on
non-subsistence receptor populations such as commercial farmers,
recreational anglers, and non-farm residents whose numbers and
locations can be estimated from available census data. At the same
time, we retained the subsistence scenarios and revised them to be more
reflective of a subsistence lifestyle. Although it is not known
precisely how many individuals are engaged in subsistence activities or
exactly where those activities take place, subsistence does occur in
some segments of the U.S. population, and we believe it is important to
evaluate the associated risks.
D. How Were Exposure Factors Determined?
Since the risk assessment at proposal, we have developed new
information on factors that are used to estimate exposures. We obtained
data collected from previously published studies and used the data to
derive exposure factor information, including information for
children.321 In particular, we reanalyzed data collected by
USDA to estimate consumption of home-produced foods, such as meat,
milk, poultry, fish, and eggs. Over half of farm households report
consuming home-produced meats, including nearly 40 percent that report
consumption of home-produced beef. In the Northeast, nearly 40 percent
of farm households report consuming home-produced dairy products, and,
in the Midwest, nearly 20 percent do. The percentage is lower
elsewhere, averaging about 13 percent nationally. Presumably most of
these households are associated with dairy farms. Most farm households
that consume home-produced foods are engaged in farming as an
occupation rather than a means of subsistence.
---------------------------------------------------------------------------
\321\ EPA published the new exposure factor information in the
``Exposure Factors Handbook,'' EPA/600/P-95/002Fb, August, 1997.
---------------------------------------------------------------------------
The data indicate that individual consumption of home-produced
foods is
[[Page 52999]]
higher than consumption of the same foods in the general populace. We
have used the information on home-produced foods to estimate the
exposures to farm households and to households engaged in subsistence
farming. Only the primary food commodity produced on the farm was
assumed to be consumed by farm households. In contrast, a wide variety
of foods was assumed to be produced and consumed by households engaged
in subsistence farming.
E. How Were Risks from Mercury Evaluated?
Commenters viewed the absence of a quantitative assessment of risks
from mercury as a significant failing at proposal. However, a number of
issues related to assessing risks from mercury had not been adequately
resolved at the time of proposal that would have allowed us to proceed
with a quantitative analysis. We have since issued our Mercury Study
Report to Congress, a study that has been subject to extensive peer
review, and the Utility Study Report to Congress.322
323 With today's rule, we conclude that sufficient technical
basis exists for conducting a quantitative assessment of mercury risks
from hazardous waste combustors. We recognize, however, that
significant uncertainties remain and the results of our mercury
analysis should be interpreted with caution and be used only
qualitatively.
---------------------------------------------------------------------------
\322\ ``Mercury Study Report to Congress, Volume III: Fate and
Transport of Mercury in the Environment,'' U.S. Environmental
Protection Agency, EPA-452/R-97-005, December 1997.
\323\ ``Study of Hazardous Air Pollutant Emissions from Electric
Utility Steam Generating Units--Final Report to Congress,'' U.S.
Environmental Protection Agency, EPA-453/R-98-004a and b, February
1998.
---------------------------------------------------------------------------
Although the mercury analysis that accompanies today's rule is
patterned after the analysis done for the Mercury Study, there are
differences between the two studies in the methods used. The model we
used for evaluating the fate and transport of mercury in lakes is the
same as the IEM-2M model used in the Mercury Study Report to Congress.
However, modifications were made to adapt it for use with rivers and
streams.324 Both studies used the ISC air dispersion model
for modeling wet deposition of mercury. However, for the Mercury Study
the ISC model was modified to include dry deposition of mercury vapor
whereas, for the current analysis, we used a simplified treatment of
dry vapor deposition. In the Mercury Study, air modeling was carried
out to a distance of 50 kilometers whereas, for the current analysis,
air modeling (and, therefore, the effective size of the modeled
watersheds) was limited to a distance of 20 kilometers. Long-range
transport of mercury emissions (beyond 50 kilometers) was considered in
the Mercury Study but was not included in the current analysis. In the
Mercury Study, a large number of different sources were investigated to
identify whether reductions in anthropogenic or environmental sources
of mercury would reduce the total exposures of mercury to the general
population. The current analysis was designed to assess what reductions
may occur in incremental exposures from specific industrial sources of
mercury to specific individuals rather than what reductions would occur
in total exposures of mercury. Also, the Mercury Study modeled
exposures under varying background assumptions, but the current
analysis did not assess the impact that variable background
concentrations would have on the risk results. In addition, the Mercury
Study received external peer review, whereas we have not conducted an
external peer review of the current analysis.
---------------------------------------------------------------------------
\324\ For a discussion of the mercury surface water model, see
the background document, ``Human Health and Ecological Risk
Assessment Support to the Development of Technical Standards for
Emissions from Combustion Units Burning Hazardous Wastes: Background
Document--Final Report,'' July, 1999.
---------------------------------------------------------------------------
In addition, there are a variety of uncertainties related to the
fate and transport of mercury in the environment, such as the
deposition of mercury emitted to the atmosphere via wet and dry removal
processes, the transport of mercury deposited in upland areas of a
watershed to a body of water, and the disposition of mercury in the
water body itself, including methylation and demethylation processes,
sequestering in the water column and sediments, and uptake in aquatic
organisms. Furthermore, the form of mercury emitted by a given facility
is thought to be a determining factor in the fate and transport of
mercury in the atmosphere. Only limited data are available on the form
of the mercury emitted from hazardous waste combustors. A more complete
discussion of the uncertainties related to the fate and transport of
mercury may be found in the Mercury Study Report to Congress.
Also important to consider is that the reference dose for methyl
mercury represents a ``no-effects'' level that is presumed to be
without appreciable risk. We used an uncertainty factor of 10 to derive
the reference dose for methyl mercury from a benchmark dose that
represents the lower 95% confidence level for the 10% incidence rate of
neurologic abnormalities in children.325 Therefore, there is
a margin of safety between the reference dose and the level
corresponding to the threshold for adverse effects, as indicated by the
human health data. Furthermore, we applied the reference dose, which
was developed for maternal exposures, to childhood exposures. This
introduces additional uncertainty in the risk estimates for children.
Additional uncertainties associated with assessing individual mercury
risks to nonsubsistence populations and subsistence receptors are
discussed under the ``Human Health Risk Characterization'' section
below.
---------------------------------------------------------------------------
\325\ The uncertainty factor is intended to cover three areas of
uncertainty: Lack of data from a two-generation reproductive assay;
variability in the human population, in particular the wide
variation in the distribution and biological half-life of methyl
mercury; and lack of data on long term sequelae of developmental
effects.
---------------------------------------------------------------------------
We do not know the direction or magnitude of many of the
uncertainties discussed above and did not attempt to quantify the
overall uncertainty of the analysis. Thus, the cumulative impact of
these uncertainties is unknown, and the uncertainties implicit in the
quantitative mercury analysis continue to be sufficiently great so as
to limit its ultimate use for decision-making. Therefore, we have used
the quantitative assessment to make qualitative judgments about the
risks from mercury but have not relied on the quantitative assessment
(nor do we believe it is appropriate) to draw quantitative conclusions
about the risks associated with particular national emissions
standards.
F. How Were Risks From Dioxins Evaluated?
Few changes have been made to the methods used for assessing risk
from dioxins since proposal. Some commenters thought we should modify
the toxicity equivalence factors that are used to characterize the
relative risk from 2,3,7,8-chlorine substituted congeners relative to
that from 2,3,7,8,-tetrachlorodibenzo(p)dioxin. As a matter of policy,
we continue to use the international consensus values that were
published by EPA in 1989. We are aware that revisions to the toxicity
equivalence factors are being considered by the international
scientific community. However, we have not adopted revised values and
continue to use the 1989 toxicity equivalence factors.
We have changed the data being relied upon to characterize the
bioaccumulation of dioxins in fish. Specifically, we believe that the
biota-
[[Page 53000]]
sediment accumulation factors used at proposal, which were derived from
data for the Great Lakes, significantly understate the bioaccumulation
potential in aquatic systems that have recent and ongoing
contamination. Studies in Sweden and elsewhere show that where
contamination is ongoing, biota-sediment accumulation factors may be
higher by as much as an order of magnitude or more relative to the
Great Lakes and other aquatic systems where levels in biota are
influenced primarily by past contamination. For the risk assessment for
today's rule, biota-sediment accumulation factors were derived from
data collected by the Connecticut Department of Environmental
Protection. The Connecticut study, which is discussed in detail in the
dioxin reassessment, involved extensive monitoring of soils, sediments,
and fish near resource recovery facilities operating in the
state.326 The data show biota-sediment accumulation factors
that are a factor of two to nine times higher (depending on the
individual congener) than those used previously.
---------------------------------------------------------------------------
\326\ ``Estimating Exposure to Dioxin-Like Compounds, Volume
III: Site-Specfic Assessment Procedures, U.S. Environmental
Protection Agency, External Review Draft, EPA/600/6-88/005Cc, June
1994
---------------------------------------------------------------------------
G. How Were Risks from Lead Evaluated?
Risks from exposures to lead were assessed at proposal by comparing
model-predicted lead levels in soil to a health-based soil benchmark
criterion. Commenters pointed out that there are pathways of exposure
other than those related to soils and that we should look at the
overall impact of lead emissions on blood lead levels in children. We
agree with these comments and have modified the risk assessment to
include other pathways of exposure such as inhalation and dietary
exposures, in addition to soil ingestion. The revised assessment
employs the Intake/Exposure Uptake BioKinetic model to assess the
incremental impact of lead intake on blood lead levels in children. The
results of the blood lead modeling are used together with information
on background levels of blood lead in the general population to
estimate the number of children whose blood levels exceed 10 micrograms
per deciliter. Our goal is to reduce children's blood lead to below
this level.
H. What Analytical Framework Was Used To Assess Human Exposures and
Risk?
As a result of the public and peer review comments received on the
risk assessment at proposal, we modified the analysis to focus on the
entire population of persons that are exposed to facility emissions
rather than persons living on a few individual farms and residences. A
study area was defined for each sample facility as the area surrounding
the facility out to a distance of 20 kilometers (or about 12 miles).
All persons residing within the study area were included in the
analysis.327 The study area was divided up into sixteen (16)
sectors defined by the intersection of rings at two, five, ten and
twenty kilometers and radii extending to the north, south, east, and
west. For each sector, census data were used to estimate the population
of those persons living in farm households by type of farm and the
population of those persons living in non-farm households. Census data
were also used to determine the age of all household members. Four age
groups were delineated: Preschoolers (0 to 5 years), preteens (6 to 11
years), adolescents (12 to 19 years) and adults (20 years and older).
---------------------------------------------------------------------------
\327\ Because the analysis at proposal indicated that exposures
beyond 20 kilometers were well below levels of concern, we did not
consider persons exposed to facility emissions that are transported
beyond 20 kilometers. Also, as discussed elsewhere, the risk
assessment was peer reviewed in accordance with EPA guidelines, and
peer reviewes did not comment that the range of the local scale
study area was insufficient (or recommend that it be increased to 50
or more kilometers).
---------------------------------------------------------------------------
Within each study area, three or four bodies of water were chosen
for analysis based on their proximity to the sample facility and the
likelihood of their being used for recreational purposes, as indicated
by factors such as size and accessibility. Water bodies were also
chosen if they were used to supply drinking water to the surrounding
community. The watershed of each water body was delineated out to a
distance of 20 kilometers from the facility.
We conducted a multi-pathway exposure analysis for all the human
receptors considered in the risk assessment. Household members
regardless of the type of household were assumed to be exposed to
facility emissions through direct inhalation and incidental ingestion
of soil. In addition, in study areas where surface waters are used for
drinking water, household members were also assumed to be exposed
through tap water ingestion. A portion of non-farm households were
assumed to engage in home gardening based on the prevalence of home
gardening in national surveys. Farm households were assumed to consume
the primary food commodity produced on the farm. This contrasts with
the subsistence farmer who was assumed to consume predominantly home-
produced foods, including meat, milk, poultry, fish, and eggs, as well
as fruits and vegetables. For the purpose of characterizing the range
of risks that could result from subsistence farming, it was assumed
that a subsistence farm was located in every sector in a given study
area. A portion of the households in each study area were assumed to
engage in recreational fishing based on the prevalence of recreational
fishing in national surveys. It was assumed that individual
recreational anglers would fish at all of the water bodies delineated
in a given study area. In contrast, households engaged in subsistence
fishing were assumed to consume fish from only a single body of water.
For the purpose of characterizing the range of risks that could result
from subsistence fishing, the assumption was made that every body of
water delineated in a given study area was used for subsistence
fishing.
Air dispersion and deposition modeling were performed for each
study area at all sample facilities using facility-specific information
on stack configuration and emissions, along with site-specific
meteorological data, terrain data (in areas of elevated terrain), and
land use data. Air modeling was conducted to a distance of 20
kilometers. Long-range transport of emissions beyond this distance was
not considered. Bioaccumulation in the terrestrial food chain was
modeled from estimates of deposition and uptake in plants and
subsequent uptake in agricultural livestock from consumption of forage
and silage. Bioaccumulation in the aquatic food chain was modeled from
estimates of deposition to watershed soils (and subsequent soil erosion
and runoff) and direct deposition to water bodies and subsequent uptake
in fish. Surface water modeling was conducted for each body of water
using site-specific information relative to watershed size, surface
runoff, soil erosion, water body size, and dilution flow.
Exposure modeling was performed using central tendency exposure
factors (e.g., duration of exposure and daily food intake) for all
receptor populations. As noted below, an exposure variability analysis
was also performed for selected constituents and receptor populations
using exposure factor distributions. Exposure pathways varied depending
on the particular human receptor and the types of activities that lead
to human exposures. Age-specific rates of mean daily food intake and
media contact rates, in conjunction with sector-specific media
concentrations and concentrations in food, were used
[[Page 53001]]
to calculate the total (administered or potential) dose from all
exposure pathways combined. Lifetime average daily dose was used as the
exposure metric for assessing cancer risk and average daily dose
(reflecting less than lifetime exposure) was used for assessing risks
of non-cancer effects.
We estimated the risk of developing cancer from the estimated
lifetime average daily dose and the slope of the dose-response curve. A
cancer slope factor is derived from either human or animal data and is
taken as the upper bound on the slope of the dose-response curve in the
low-dose region, generally assumed to be linear, expressed as a
lifetime excess cancer risk per unit exposure. Total carcinogenic risk
was determined for each receptor population assuming additivity. The
same approach was used for estimating cancer risks in both adults and
children. This is also the same approach we used at proposal for
estimating lifetime cancer risks stemming from childhood exposures.
However, individuals exposed to carcinogens in the first few years of
life may be at increased risk of developing cancer. For this reason, we
recognize that significant uncertainties and unknowns exist regarding
the estimation of lifetime cancer risks in children. Although the risk
assessment at proposal was externally peer reviewed, EPA's charge to
the peer review panel did not specifically identify the issue of cancer
risk in children and the peer review panel did not address it.
To characterize the potential risk of non-cancer effects, we
compared the average daily dose (reflecting less than lifetime
exposure) to a reference dose and expressed the result as a ratio or
hazard quotient. The reference dose is an estimate of a daily exposure
to the human population, including sensitive subgroups, that is likely
to be without an appreciable risk of deleterious effects during a
lifetime. The hazard quotient, by indicating how close the average
daily dose is to the reference dose, is a measure of relative risk.
However, the hazard quotient is not an absolute measure of risk. For
inhalation exposures, we compared modeled air concentrations to a
reference concentration and expressed the result as a ratio or
inhalation hazard quotient. The reference concentration is an estimate
of a concentration in air that is likely to be without an appreciable
risk of deleterious effects in the human population, including
sensitive subgroups, from continuous exposures over a lifetime. In
addition, inhalation and ingestion hazard indices were generated for
each receptor population by adding the constituent-specific hazard
quotients by route of exposure. The hazard index is an indicator of the
potential for risk from exposures to chemical mixtures.
For dioxins, we used a margin of exposure approach to assess the
potential risks of non-cancer effects. The average daily dose, in terms
of 2,3,7,8-TCDD toxicity equivalents (TEQ), was compared to background
TEQ exposures in the general population and expressed as a ratio or
incremental margin of exposure. An incremental margin of exposure was
generated for infants exposed through intake of breast milk and for
other age groups exposed through dietary intake and other pathways of
exposure. For lead, we characterized the risk of adverse effects in
children by modeling body burden levels in blood that result from
intake of lead in the diet, direct inhalation, and incidental soil
ingestion and comparing these levels to levels at which community-wide
efforts aimed at prevention of elevated blood levels are indicated.
Distributions of individual risk were generated for a given
category of sources by weighting the individual risks using sector-
specific population weights and facility-specific sampling weights.
Such distributions, which were derived using central tendency exposure
factors, were generated for all constituents and receptor populations.
In addition, for those receptor populations and chemical constituents
that exhibited risks within an order of magnitude of a potential level
of concern (using central tendency exposure factors), we performed an
exposure variability analysis. Normalized, age-specific distributions
of food intake and exposure duration were used to adjust the risk
estimates to generate a distribution of risks in each sector. For
children, food intake changes significantly with age, which can affect
the lifetime average daily dose. To adjust for this, a life table
analysis was conducted in which individuals were followed over the
duration of exposure to arrive at an age adjustment factor. The
individual sector distributions were combined for a given source
category using Monte Carlo sampling and the appropriate sector-specific
population weights and facility-specific sampling weights.
Estimates of population risk, or the incidence of health effects in
the exposed population, were made for selected receptor populations and
chemical constituents. Local excess cancer incidence was estimated from
the mean individual risk for a given sector and the number of persons
who reside in a sector. These sector-specific cancer incidence rates
were then adjusted using facility-specific sampling weights and summed
for a given category of sources. Cancer incidence associated with the
consumption of dioxin contaminated beef, pork, and milk by the general
population was estimated at the sector level from the number of dairy
cattle and the number of beef cattle and hogs slaughtered annually,
adjusted using facility-specific sampling weights, and summed by source
category. Excess incidence of lead poisoning in children (over and
above background) was estimated at the sector level from the intake of
lead in the diet, direct inhalation, and incidental soil ingestion,
adjusted using facility-specific sampling weights, and summed.
Generally speaking, incidence rates for non-cancer effects can be
estimated from the number of persons exposed above the reference dose
(i.e., the number of exceedances) and the annual turnover in the
exposed population. However, non-cancer incidence rates of interest,
such as the incidence of exceedances of the methyl mercury reference
dose from consumption of freshwater fish, could not be estimated due to
the difficulty in determining the number and frequency of visits made
by recreational anglers to a given body of water. However, by making
certain assumptions, it was possible to make an estimate of the portion
of recreational anglers who consume fish from local water bodies that
may be at risk.328
---------------------------------------------------------------------------
\328\ The assumption is that fishing activity typical of
recreational fishing takes place only at the particular water bodies
delineated in the analysis.
---------------------------------------------------------------------------
Due to concerns of commenters about the representativeness of the
risk assessment, we also made estimates of confidence intervals about
the risk estimates. Estimation of confidence intervals was made
possible by virtue of the sampling design used for facility selection.
The confidence intervals quantify the magnitude of the uncertainty of
the risk estimates associated with sampling error only. We emphasize
that the confidence intervals do not reflect other sources of
uncertainty, which may be of considerably greater magnitude.
In addition to the risk estimates for individual chemical
constituents, we estimated the incidence of excess mortality and
morbidity associated with particulate matter emissions. Mortality and
morbidity estimates were made for children and the elderly, as well as
the general population, using concentration-response functions derived
from human epidemiological studies. Incidence rates
[[Page 53002]]
in a given sector were estimated from the size of the exposed
population, including susceptible populations such as children and the
elderly, and either annual mean PM10 and PM2.5
concentrations or distributions of daily PM10 and
PM2.5 concentrations. Morbidity effects include respiratory
and cardiovascular illnesses requiring hospitalization, as well as
other illnesses not requiring hospitalization, such as acute and
chronic bronchitis, acute upper and lower respiratory symptoms, and
asthmatic attacks. As with other incidence estimates, sector-specific
incidence rates were adjusted using facility-specific sampling weights
and summed for a given source category.
I. What Analytical Framework Was Used to Assess Ecological Risk?
Public comments on the ecological assessment at proposal expressed
the view that we should expand the assessment beyond water quality
criteria. We agree with these commenters and have extended the
ecological analysis to include the use of soil and sediment criteria,
in addition to water quality criteria. Also, the analysis was expanded
to include additional metals that are of ecological concern, such as
mercury and copper.
The ecological assessment represents a screening level analysis
that uses media-specific ecological criteria thought to be protective
of a range of ecological receptors. Modeled surface water
concentrations were compared to water quality criteria protective of
aquatic life, such as algae, fish, and aquatic invertebrates, as well
as piscivorous wildlife. Similarly, modeled soil concentrations were
compared to soil criteria protective of the terrestrial soil community,
as well as terrestrial plants and mammalian and avian wildlife. Modeled
sediment concentrations were compared to sediment criteria protective
of the benthic aquatic community. As a screening level analysis, we did
not attempt to determine whether the specific ecological receptors upon
which the media-specific criteria are based are actually present at a
given site. Furthermore, we did not ascertain the occurrence of
threatened or endangered species at individual sites. However, the
ecological receptors upon which the media-specific criteria are based
are commonly occurring species and may not be any less sensitive than
other species and may be more sensitive than some, including perhaps
threatened or endangered species.329
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\329\ Multiple ecological criteria were available for most
constituents and the lowest criteria were used to establish the
media-specific values that were in the eco-analysis. In addition,
ecotoxicological benchmarks for mammals and birds were typically
derived from studies involving measures of reproductive success.
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II. How Were Human Health Risks Characterized?
This section describes the conclusions of the human health risk
assessment. For a full discussion of the methodology and the results of
the assessment, see the background document for today's
rule.330
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\330\ ``Human Health and Ecological Risk Assessment Support to
the Development of Technical Standards for Emissions from Combustion
Units Burning Hazardous Wastes: Background Document--Final Report,''
July 1999.
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A. What Potential Health Hazards Were Evaluated?
This section summarizes the potential health hazards from exposures
to emissions from hazardous waste combustors, in particular the human
health hazards associated with the chemical constituents evaluated in
the risk assessment, including dioxins, mercury, lead, other metals,
hydrogen chloride and chlorine, and particulate matter.
1. Dioxins
A large body of evidence demonstrates that chlorinated
dibenzo(p)dioxins and dibenzofurans can have a wide variety of health
effects, ranging from cancer to various developmental, reproductive and
immunological effects. Dioxins are persistent and highly
bioaccumulative in the environment and most human exposures occur
through consumption of foods derived from animal products such as meat,
milk, fish, poultry, and eggs. In 1985, we developed a carcinogenic
slope factor for 2,3,7,8-TCDD of 1.56e-4 per picogram per kilogram body
weight per day.331 The slope factor represents the 95
percent upper confidence limit estimate of the lifetime excess cancer
risk. Re-analysis of data from laboratory animals and cancer in humans
lends support to the slope factor derived in 1985, and we continue to
use the 1985 estimate pending completion of our dioxin
reassessment.332 333
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\331\ USEPA, ``Health Assessment Document for Polychlorinated
Dibenzo-p-Dioxins,'' EPA/600/8-84-014F, September 1985.
\332\ USEPA, ``Health Assessment Document for 2,3,7,8-
Tetrachlorodibenzo-p-Dioxin (TCDD) and Related Compounds,'' External
Review Draft, EPA/600/BP-92/001b, June 1994.
\333\ USEPA, ``Dose Response Modeling of 2,3,7,8-TCDD,''
Workshop Review Draft, EPA/600/P-92/100C8, January 1997.
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For non-cancer effects, we believe it is inappropriate to develop a
reference dose, or level which is without appreciable risk, using
standard uncertainty factors. This is due to the high levels of
background exposures in the general population and the low levels at
which effects have been seen in laboratory animals. Instead, we have
chosen to use a margin of exposure approach in which the average daily
dose from a given facility is compared to the average daily dose in the
general population. The ratio of the two represents the incremental
margin of exposure and, as such, measures the relative increase in
exposures over background.
2. Mercury
The most bioavailable form of mercury is methyl mercury, and most
human exposures to methyl mercury occur through consumption of fish.
Methyl mercury is known to cause neurological and developmental effects
in humans at low levels. The most susceptible human population is
thought to be developing fetuses. We have developed a reference dose
for methyl mercury of 0.1 microgram per kilogram body weight per day
that is presumed to be protective of the most sensitive human
populations.334 The reference dose is based on neurotoxic
effects observed in children exposed in utero. Although epidemiological
studies in fish-eating populations are ongoing, we believe that the
reference dose is the best estimate at the present time of a daily
exposure that is likely to be without an appreciable risk of
deleterious effects. However, because it was derived from maternal
exposures, application of the reference dose to assess children's
exposures carries with it additional uncertainty beyond that otherwise
related to the data and methods used for its development.
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\334\ USEPA, ``Mercury Study Report to Congress,'' EPA-452/R-97-
007, December 1997.
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3. Lead
Exposures to lead in humans are associated with toxic effects in
the nervous system at low doses and at higher doses in the kidneys and
cardiovascular system. Infants and children are particularly
susceptible to
[[Page 53003]]
the effects of lead due to behavioral characteristics such as mouthing
behavior, heightened absorption in the respiratory and gastrointestinal
tracts, and the intrinsic sensitivity of developing organ systems.
Symptoms of neurotoxicity include impairment in psychomotor, auditory,
and cognitive function. These effects extend down to levels in blood of
at least 10 micrograms lead per deciliter. Impairment of intellectual
development, as measured by standardized tests, is thought to occur at
levels below 10 micrograms per deciliter. Maternal lead exposure has
been shown to be a risk factor in premature infant mortality, lead
being associated with reduced birth weight and decreases in gestational
age. Lead has also been associated with hypertension in both men and
women and, as such, may be a risk factor for coronary disease, stroke,
and premature mortality. Although dose-response relationships have been
developed between blood lead levels and many of these health effects,
EPA has not applied the relationships in the HWC risk analysis due to
uncertainties related to the relatively small changes in blood lead
expected to occur as a consequence of the MACT standards and the
uncertain significance of any health benefits that might be attributed
to such changes. Instead, our characterization of risks from lead
focuses on the reductions in blood levels themselves and EPA's goal of
reducing blood lead in children to below 10 micrograms per deciliter.
4. Other Metals
Metals that pose a risk for cancer include arsenic, cadmium, and
chromium. Human epidemiological studies have shown an increase in lung
cancer from inhalation exposures to arsenic, primarily in
occupationally exposed individuals, and multiple internal cancers (such
as liver, lung, kidney, and bladder), as well as skin cancer, from
exposures to arsenic through drinking water. Human epidemiological
studies have also shown an association between exposures to cadmium and
lung cancer in occupational settings. These studies have been confirmed
by animal studies which have shown significant increases in lung tumors
from inhalation exposures to cadmium. However, cadmium administered
orally has shown no evidence of carcinogenic response. A strong
association between occupational exposures to chromium and lung cancer
has been found in multiple studies. Although workers were exposed to
both trivalent and hexavalent chromium, animal studies have shown that
only hexavalent chromium is carcinogenic. There have been no studies
that have reported that either hexavalent or trivalent chromium is
carcinogenic by the oral route of exposure.
Other metals may pose a risk of noncancer effects. For example, in
animal studies thallium has been shown to have ocular, neurological,
and dermatological effects and effects on blood chemistry and the
reproductive system. Signs and symptoms of similar and other effects
have been observed in occupational studies of thallium exposures.
5. Hydrogen Chloride
Data on the effects of low-level inhalation exposures to hydrogen
chloride are limited to studies in laboratory animals. Based on a
lifetime study in rats which showed histopathological changes in the
nasal mucosa, larynx, and trachea associated with exposures to hydrogen
chloride, we estimated a reference concentration of 0.02
milligrams per cubic meter. The reference concentration was derived
from a human equivalent lowest observed adverse effects level of 6
milligrams per cubic meter using an uncertainty factor of 300 to
account for extrapolation from a lowest observed adverse effects level
to a no observed adverse effects level, as well as extrapolation from
animals to humans (including sensitive individuals).
6. Chlorine
Chlorine gas is a potent irritant of the eyes and respiratory
system. Based on a lifetime study in rats and mice which showed
histopathological changes affecting all airway tissues in the nose, we
derived an interim chronic toxicity benchmark for chlorine gas of 0.001
milligrams per cubic meter. This value was derived from a human
equivalent no observed adverse effects level of 0.04 milligrams per
cubic meter and an uncertainty factor of 30 to account for
extrapolation from animals to humans (including sensitive individuals).
The human equivalent no observed adverse effects level from this study
is also supported by a year-long study in monkeys.335
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\335\ For a complete description of the derivation of the
chronic toxicity benchmark for chlorine, see the background
document, ``Human Health and Ecological Risk Assessment Support to
the Development of Technical Standards for Emissions from Combustion
Units Burning Hazardous Wastes: Background--Final Report,'' July,
1999.
---------------------------------------------------------------------------
B. What Are the Health Risks to Individuals Residing Near HWC
Facilities?
In this section, we address risks to populations that could be
enumerated using estimation methods based on U.S. Census data and
Census of Agriculture data. Estimates of the population of persons
residing within 20 kilometers of hazardous waste combustion facilities
were made for beef, dairy, produce, and pork farming households and for
non-farm households. The number of home gardeners was estimated using
national survey data on the portion of households that engage in home
gardening. Estimates were made for each of four different age groups.
In addition, population estimates were made for recreational anglers
age 16 and older based on U.S. Fish and Wildlife Service survey data on
recreational fishing and hunting.336
---------------------------------------------------------------------------
\336\ However, it was not possible to determine the number of
recreational anglers that fish specifically at water bodies located
in the vicinity of hazardous waste combustion facilities, such as
those that were selected for modeling analyses.
---------------------------------------------------------------------------
The risks to individuals of carcinogenic effects are expressed as
the estimated increase in the probability that an individual will
develop cancer over a lifetime. For non-cancer effects, risks are
expressed as a hazard quotient, which is the ratio of an estimate of an
individual's exposure to a health benchmark thought to be without
appreciable risk. Both cancer and non-cancer risks are summarized in
terms of percentiles of the national distribution of risks to
individuals across a combustor category. High end risks are represented
by the 90th to 99th percentiles of the distribution. Distributions for
only the most highly exposed receptor populations are discussed here.
The most highly exposed population varies depending on the particular
chemical constituent, its fate and transport in the environment, and
the pathways that lead to human exposures. Also, 90 percent confidence
limits are estimated for each percentile. The size of the confidence
interval reflects sampling error which is introduced by not sampling
all the facilities in a given category of sources.\337\ In some
instances, estimates of the 90 percent confidence limits could not be
made either because there were too few data points or there was
insufficient spread in the data. For lightweight aggregate kilns, there
is no sampling error because the sample included all known
[[Page 53004]]
hazardous waste burning lightweight aggregate kilns.
---------------------------------------------------------------------------
\337\ A 90 percent confidence interval indicates that there is a
10 percent chance that the actual value could lie outside the
interval indicated, either higher or lower.
---------------------------------------------------------------------------
1. Dioxins
For dioxins, our analysis shows that the most exposed population is
children of dairy farmers who consume home-produced milk. High
exposures were estimated for this population due to the relatively high
consumption of milk by households that consume home-produced milk, the
relatively high intake of milk by children compared to other age
groups, and the tendency of chlorinated dioxins and furans to
bioaccumulate in milk fat. A distribution of cancer risks for dioxins
was generated which reflects variability in individual exposures due to
site-specific differences in dioxin emissions, location of exposure,
and other factors, as well as differences between individuals in
exposure factors such as the length of exposure and the amount of milk
consumed.
As a result of today's rule, we project that high end lifetime
excess cancer risks will be reduced in this population from 2 in
100,000 (99th percentile) for both lightweight aggregate kilns and
incinerators with waste heat recovery boilers to below one in one
million (99th percentile) for lightweight aggregate kilns and 1 in one
million (99th percentile, 90 percent upper confidence limit of 2 in one
million) for incinerators with waste heat recovery boilers. For cement
kilns, high end lifetime excess cancer risks are reduced only slightly,
from 7 in one million (99th percentile) to 5 in one million (99th
percentile). These reductions, which represent the reduction in the
increment of exposure that results from dioxin emissions from hazardous
waste combustors, are relatively small in relation to background
exposures to dioxins generally. Considering that the number of
individuals in the affected population is relatively small, only a few
individuals may benefit from such reductions.
We also project that the incremental margin of exposure relative to
background will be reduced in the same population from 0.2 (99th
percentile for lightweight aggregate kilns) and 0.3 (99th percentile
for incinerators with waste heat recovery boilers, 90 percent upper
confidence limit of 0.5) to below 0.1 across all categories of
combustors. Therefore, the risks associated with non-cancer effects
from hazardous waste combustors are an order of magnitude or more lower
than any (unknown and unquantifiable) risks that may be attributable to
background exposures.
Unlike the distribution of cancer risks, the distribution of the
margin of exposure reflects only site-to-site differences and does not
reflect differences between individuals in the amount of milk consumed.
Therefore, the exposures at the upper percentiles are likely to be
underestimated.338 Additional uncertainty is introduced
because background exposures to dioxins in children have not been well
characterized.
---------------------------------------------------------------------------
\338\ The precise extent of underestimation at the upper
percentiles associated with variability in milk consumption is
unknown but is expected to be a factor of two.
---------------------------------------------------------------------------
Other uncertainties include milk consumption rates and the
limitations of the data available to assess consumption of home-
produced milk. In addition, there are a variety of uncertainties
related to the fate and transport of dioxins in the environment,
including partitioning behavior into vapor and particle phases
following release to the atmosphere and subsequent deposition via
various wet and dry removal processes, uptake in plants such as forage
and silage used by dairy cows for grazing and feeding, and the factors
which affect the disposition of dioxins in dairy cattle and the extent
of bioaccumulation in cow's milk.
2. Mercury
For mercury, our analysis shows that the most exposed population is
recreational anglers and their families who consume recreationally-
caught freshwater fish. This is because methyl mercury is readily
formed in aquatic ecosystems and bioaccumulates in fish. Children have
the highest exposures due to their higher consumption of fish, relative
to body weight, compared to adults. Risks from exposures to methyl
mercury are expressed here in terms of a hazard quotient, which is
defined as the ratio of the modeled average daily dose to our reference
dose. Although the reference dose was developed to be protective of
exposures in utero, we applied the reference dose not just to maternal
exposures but also to non-maternal adult and childhood exposures based
on the presumption that the reference dose should be protective of
neurological and developmental effects in these populations as well.
A distribution of hazard quotients was generated that reflects
variability in individual exposures due to site-specific differences in
mercury emissions, location of water bodies, and other factors, as well
as differences between individuals in the amount of fish consumed.
Other factors, such as water body-specific differences in the extent of
methylation of inorganic mercury and the age and species of fish
consumed were not reflected in the risk distribution. However, it is
unclear what effect such factors would have on the distribution given
the high degree of variability that is attributable to the factors that
were considered in our analysis.
The results of our quantitative analysis for mercury are as
follows. For cement kilns, we project that high end hazard quotients in
adults will be reduced from a range of 0.09 to 0.4 (90th percentile,
upper confidence limit of 0.1, and 99th percentile, respectively) at
baseline to a range from 0.06 to 0.2 under today's rule (90th
percentile, upper confidence limit of 0.08, and 99th percentile,
respectively). In children, high end hazard quotients are projected to
be reduced from a range of 0.2 to 0.8 (90th percentile, upper
confidence limit of 0.3, and 99th percentile, respectively) at baseline
to a range of 0.2 to 0.6 under today's rule (90th percentile, upper
confidence limit of 0.2, and 99th percentile, respectively). For
lightweight aggregate kilns, high end hazard quotients in both adults
and children are below 0.1 at baseline and under today's rule. For
incinerators, high end hazard quotients are below 0.01 in adults and
below 0.1 in children at baseline and under today's rule. Taken
together, these results appear to suggest that risks from mercury
emissions (on an incremental basis) are likely to be small, although we
cannot be certain of this for the reasons discussed below.
The risk results for mercury are subject to a considerable degree
of uncertainty. In addition to the uncertainties discussed above in
``Overview of Methodology--Mercury'', there are other uncertainties
when assessing individual mercury risks to nonsubsistence populations.
In order to assess exposures to mercury emissions, we assumed that
recreational anglers fish only at the water bodies within a given study
area that were selected for modeling (and at no other water bodies) and
that the extent of fishing activity at a given water body is related to
the size of the water body.339 As a result, in those
situations where relatively low fish concentrations were modeled (and
particularly if the water body was relatively large), a large portion
of fish were assumed to have relatively low levels of mercury
contamination and, therefore, recreational anglers who consume
relatively large amounts of recreationally-caught fish were estimated
to have relatively low levels
[[Page 53005]]
of exposure. In reality, some portion of the fish consumed by
recreational anglers is likely to be contaminated with mercury at
levels typical of background conditions. The effect of such background
exposures is to increase actual exposures, except perhaps at the high
end of the exposure distribution.340
---------------------------------------------------------------------------
\339\ Ideally, detailed information on the fishing activities of
individual anglers, including the size of the catch taken from
individual locations, would be used to better assess exposures from
consumption of recreationally-caught fish.
\340\ We have previously estimated that median exposures to
methyl mercury in the general population from seafood consumption
are in the range of 0.01 to 0.03 g/kg BW/day (Mercury Study
Report to Congress, December 1997). These exposures correspond to
hazard quotients of 0.1 to 0.3, values which (except for cement
kilns) are higher than the 90th to 99th percentile hazard quotients
estimated here for incremental exposures among recreational anglers.
---------------------------------------------------------------------------
We believe that the uncertainties implicit in the quantitative
mercury analysis continue to be sufficiently great so as to limit its
ultimate use for decision-making. Therefore, we have used the
quantitative analysis to make qualitative judgments about the risks
from mercury but have not relied on the quantitative analysis (nor do
we believe it is appropriate) to draw quantitative conclusions about
the risks associated with the MACT standards.
3. Lead
For lead, children are the population of primary concern for
several reasons, including behavioral factors, absorption, and the
susceptibility of the nervous system during a child's development. We
have chosen to use blood lead level as the exposure metric, consistent
with the U.S. Centers for Disease Control criteria for initiating
intervention efforts. Lead exposures occur through a variety of
pathways, including inhalation, incidental ingestion of soil and
household dust, and dietary intake. Our analysis indicates that the
population having the highest exposures are children who consume home-
produced fruits and vegetables. However, children who do not consume
home-produced foods also have relatively high exposures due to
incidental ingestion of soil and household dust.
Blood lead distributions were generated that represent incremental
exposures to lead emissions from hazardous waste combustors. These
distributions reflect variability in individual exposures due to site-
specific differences in lead emissions, location of exposure, and other
factors, as well as differences between individual children in behavior
patterns, absorption, and other pharmacokinetic factors. The IEUBK
model that was used to estimate blood lead levels considers inter-
individual variability in behavior related to lead exposure, such as
mouthing activity. However, the model does not explicitly consider
variability for the specific dietary pathways assessed for children of
home gardeners, that is, consumption of home-produced fruits and
vegetables. Therefore, the blood lead distributions may not fully
reflect inter-individual variability that results from such individual
differences.
Modeled blood lead (PbB) levels can be compared with background
exposures in the same age group (children ages 0 to 5 years) in the
general population. The median blood lead level in children in the
general population is 2.7 micrograms per deciliter (g/dL), and
4.4 and 1.3 percent of children have blood lead levels that exceed 10
and 15 g/dL, the levels at which community wide prevention and
individual intervention efforts, respectively, are
recommended.341 However, the percentages vary widely
depending on such factors as race, ethnicity, income, and age of the
housing units occupied. Children whose blood lead levels are already
elevated are the most susceptible to further increases in blood lead
levels.
---------------------------------------------------------------------------
\341\ Data from the Centers for Disease Control's National
Health and Nutrition Examination survey (NHANES III, phase 2)
conducted from October 1991 to September 1994.
---------------------------------------------------------------------------
As a result of today's rule, we project that high end (90th to 99th
percentile) incremental blood lead (PbB) levels in children will
decrease from 0.24 to 0.50 micrograms per deciliter to 0.02 to 0.03
g/dL for cement kilns. For incinerators, incremental PbB
levels are projected to decrease from 0.6 to 1.2 g/dL (90th to
99th percentile) to 0.02 to 0.03 g/dL. For lightweight
aggregate kilns, incremental PbB levels are projected to decrease from
0.02 to 0.03 g/dL (90th to 99th percentile) to less than 0.01
g/dL under the MACT standards. Although these reductions in
incremental exposures represent only a fraction of the PbB level of
concern (10 g/dL), they can be significant in children with
PbB levels that are already elevated from exposures to other sources of
lead. In addition, there is evidence that effects on the neurological
development of children may occur at blood lead levels so low as to be
essentially without a threshold. Under the MACT standards, blood lead
levels attributable to HWCs will be one percent or less of background
levels typical of children in the general population.
4. Other Metals
We assessed both direct and indirect human exposures to a dozen
different metals in addition to mercury. Exposures to non-mercury
metals are generally quite low. Under today's rule, we project that
lifetime excess cancer risks from exposures to carcinogenic metals
(i.e., arsenic) will be below 1 in 10 million for all source
categories. Hazard quotients for all source categories are projected to
be at or below 0.01 (99th percentile) for all non-mercury metals under
the MACT standards. These risks reflect variability in individual
exposures due to site-specific differences in emissions, location of
exposure, and other factors. However, the risks do not reflect
differences between individuals in exposure factors such as the length
of exposure and the amount of food ingested. Therefore, we may have
underestimated risks at the upper percentiles of the
distribution.342 A full exposure factor variability analysis
was not carried out because the risks using mean exposure factors are
comparatively low. Risks from exposure to metals are also subject to
uncertainty related to modeling of fate and transport in the
environment such as deposition of airborne metals to soils, forage, and
silage and subsequent uptake in farm animals.
---------------------------------------------------------------------------
\342\ For dioxins, inclusion of exposure factor variability
increased the risk of cancer at the upper (90th to 99th) percentiles
by less than a factor of two to a factor of five. However, the
effect on the distribution of risks could differ for metals
depending on the health effect of concern (i.e., cancer versus non-
cancer), the pathway of exposure, and relative differences in the
site-to-site variability of emissions.
---------------------------------------------------------------------------
5. Inhalation Carcinogens
We also assessed the combined cancer risk associated with
inhalation exposures to all inhalation carcinogens, assuming additivity
of the risks from individual compounds. The populations that have the
highest inhalation exposures are adult farm or non-farm residents.
Adults have the longest exposure duration relative to other age groups
and adult farmers have less mobility and, therefore, longer durations
of exposure than non-farm residents. However, depending on the location
of farms and non-farm households, adult non-farm residents can have
lifetime average exposures that are as high as adult farm residents.
Under today's rule, we project that lifetime excess cancer risks
from inhalation exposures will be below 1 in 10 million for all source
categories. The risks for inhalation carcinogens reflect variability in
individual exposures due to site-specific differences in metals
emissions, location of exposure, and other factors. However, they do
not reflect differences between individuals
[[Page 53006]]
in the length of exposure or other exposure factors. Therefore, we may
have underestimated risks at the upper percentiles of the
distribution.343 A full exposure factor variability analysis
was not carried out for inhalation carcinogens because the risks using
mean exposure factors are comparatively low.
---------------------------------------------------------------------------
\343\ The precise extent of underestimation at the upper
percentiles associated with variability in the duration of exposure
is unknown but is expected to be a factor of three or less.
---------------------------------------------------------------------------
Estimates of inhalation risks are subject to a number of
uncertainties. Individuals spend a majority of their time indoors and
it is uncertain how representative modeled, outdoor, ambient air
concentrations are of concentrations indoors. Also, the daily
activities of individuals living in the vicinity of a given facility
will tend to moderate actual exposures compared to modeled exposures at
a fixed location. Meteorological information was generally obtained
from locations well removed from modeled facilities and, therefore, may
not be representative of conditions in the immediate vicinity of the
stack. Limited information was available on the size of structures
located near or adjacent to stacks at the modeled facilities. Building
downwash, that can result from the presence of such structures, may
significantly increase ground-level ambient air concentrations,
particularly at locations that are relatively close to the point of
release. In addition, the effect of elevated terrain was only
considered when the terrain rose above the height of the stack.
However, elevated terrain below stack height can lead to an increase in
ground-level concentrations depending on the distance from the stack.
Nevertheless, our projections of inhalation cancer risks are
sufficiently low that we do not believe the uncertainties introduced by
these factors impacts our conclusion that these risks are relatively
low.
6. Other Inhalation Exposures
Of the compounds we evaluated that are not carcinogenic, the
highest inhalation exposures are for hydrogen chloride and chlorine
gas. We express the risks from these in terms of an
inhalation hazard quotient, which is defined as the ratio of the
modeled air concentration to our reference concentration. The receptor
population with the highest inhalation hazard quotients is variable and
depends on site-to-site differences in the location of farm and non-
farm households and differences in emissions. A distribution of hazard
quotients was generated that reflects variability in individual
exposures due to site-specific differences in chlorine emissions,
location of exposure, and other factors. However, the distribution does
not reflect individual differences in activity patterns or breathing
rates.344 Also, because the reference concentration is
intended to be protective of long-term, chronic exposures over a
lifetime, the distribution does not reflect temporal variations in
exposure.345
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\344\ Differences in breathing rates are not considered because
the exposure factors used in deriving the reference concentration
are fixed.
\345\ Although short-term exposures to hydrogen chloride and
chlorine gas resulting from routine releases can be significantly
higher than long-term exposures, we do not believe that such
exposures are high enough to pose a health concern because the
threshold for acute effects is quite high in comparison to that for
chronic effects.
---------------------------------------------------------------------------
Under today's rule, we project that inhalation hazard quotients
will be at or below 0.01 for both hydrogen chloride and chlorine gas
for all source categories. The same uncertainties related to indoor
versus outdoor concentrations and atmospheric dispersion modeling are
also applicable to hydrogen chloride and chlorine. However, our
projections of non-cancer inhalation risks are sufficiently low that we
do not believe the uncertainties impact our conclusion that these risks
are relatively low.
C. What Are the Potential Health Risks to Highly Exposed Individuals?
We also assessed exposures to individuals that could be more highly
exposed than the populations that could be characterized using census
data. These include persons engaged in subsistence activities such as
farming and fishing. Although the frequency of these activities is
unknown, such activities do occur in some segments of the U.S.
population, and we believe that it is important to evaluate risks
associated with such activities. In addition, risks associated with
subsistence farming place a bound on potential risks to farmers who
raise more than one type of livestock. Information on the numbers of
farms that produce more than one food commodity (e.g., beef and milk)
is not available from the U.S. Census of Agriculture. Therefore, in
assessing risks to farm populations, we may have underestimated the
risks to farmers and their families that consume more than one type of
home-produced food commodity.
We assumed that subsistence farmers obtain substantially all of
their dietary intake from home-produced foods, including meats, milk,
poultry, fish, and fruits and vegetables. We used data on the mean rate
of consumption of home-produced foods in households that consume home-
produced foods to estimate the average daily intakes from subsistence
farming. For subsistence fishing, we used data on the mean rate of fish
consumption among Native American tribes that rely on fish for a major
part of their dietary intake.
We do not have specific information on the existence or location of
subsistence farms or water bodies used for subsistence fishing at sites
where hazardous waste combustors are located. Therefore, we
hypothetically assumed that subsistence farming does occur at each of
the modeled facilities and, furthermore, that it occurs within each of
the sixteen sectors within a study area. We also assumed that
subsistence fishing takes places at each of the modeled water bodies.
The results of the analysis are summarized in the form of frequency
distributions of individual risk. The distributions must be interpreted
in relation to the frequency of the modeled scenarios and not the
likelihood of such exposures actually occurring.346
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\346\ Moreover, the modeled scenarios cannot be considered
equally probable because the sectors in which farms were located are
of unequal area, being much smaller closer to a facility and much
larger farther away and because any particular sector may be more or
less likely to support farming activities depending on soils,
precipitation, existing land uses, and other conditions. Similarly,
the modeled water bodies may be more or less likely to support
intensive fishing activity depending on their size, productivity,
and other characteristics.
---------------------------------------------------------------------------
The risk results for subsistence receptors are highly uncertain,
primarily due to the lack of information on the location of subsistence
farms (or even the occurrence of subsistence farms within the study
area of a given facility) and the assumption that individuals engaged
in subsistence farming obtain essentially their entire dietary intake
from home-produced foods.
1. Dioxins
Under today's rule, we project that lifetime excess cancer risks
from dioxin exposures associated with subsistence farming will be below
1 in 100,000 for all categories of combustors, with the exception of
cement kilns at the lowest frequency of occurrence. The lifetime excess
cancer risk for cement kilns is estimated to be 2 in 100,000 at a
frequency of 1 percent. This indicates that only 1 in 100 sectors are
expected to have risks of this magnitude or greater, assuming that
subsistence farms are located in all sectors at all hazardous waste
burning cement kilns. However, because the sectors increase in size
with increasing distance, the probability that a subsistence farm would
be exposed to
[[Page 53007]]
this level of risk is probably considerably less than 1 percent.
We project that the incremental margin of exposure relative to
background will be reduced to 0.1 or below for incinerators under
today's rule except at the lowest frequency of occurrence (i.e., 1
percent) for which a margin of exposure of 0.2 is projected. However,
the incremental margins of exposure for cement kilns and lightweight
aggregate kilns are projected to remain above 0.1 at a frequency of 10
percent or greater (ranging up to 0.2 at a frequency of 5 percent for
lightweight aggregate kilns and 0.7 at a frequency of 1 percent for
cement kilns). This indicates that more than 1 in 10 sectors are
expected to have risks associated with non-cancer effects that are
within an order of magnitude of any (unknown and unquantifiable) risks
that may be attributable to background exposures. However, for the
reasons stated previously, the probability that a subsistence farm
would be exposed to this level of risk is probably considerably lower
than indicated by the number of sectors.
Under today's rule, we project lifetime excess cancer risks from
dioxin exposures associated with subsistence fishing will be below 1 in
one million for incinerators and lightweight aggregate kilns. For
cement kilns, high end cancer risks under today's rule range from 3 in
one million to 4 in one million (at frequencies of 10 and 5 percent,
respectively) in adults and from 2 in one million to 4 in one million
(at frequencies of 10 and 5 percent, respectively) in children (6 to 11
years of age). We project that the incremental margin of exposure
relative to background will be below 0.1 for subsistence fishing for
both children and adults for all categories of combustors under today's
rule.
2. Metals
Our analysis indicates that the highest risks from metals (other
than mercury) are from arsenic, thallium, and lead. Under today's rule,
we project that lifetime excess cancer risks from arsenic exposures
associated with subsistence farming will be below 1 in one million for
all source categories. Hazard quotients for thallium are projected to
be at or below 0.01 (99th percentile) under today's rule, except for
cement kilns. For cement kilns, hazard quotients for thallium are
projected to range from 0.03 to 0.4 (90th to 99th percentiles).
Incremental blood lead levels are projected to be at or below 0.03
g/dL for all source categories under today's rule. Blood lead
at these levels are about one percent of background levels typical of
children in the general population.
3. Mercury
From the results of our quantitative analysis we project that,
under today's rule, hazard quotients for incremental exposures to
mercury associated with subsistence fishing will be at or below 1 in
both adults and children. These results apply to incinerators,
lightweight aggregate kilns, and cement kilns at the very lowest
frequency of occurrence that was analyzed (i.e., 1 percent).
The risk results for mercury are subject to a considerable degree
of uncertainty. In addition to the uncertainties discussed above in
``Overview of Methodology--Mercury'', there are other uncertainties
when assessing individual mercury risks to subsistence receptors. We
assumed that individuals engaged in subsistence fishing obtain all the
fish they consume from a single water body. To the extent that
individuals may fish at more than one water body, the effect of this
assumption may be to exaggerate the risk from water bodies having
relatively high modeled fish concentrations.
The uncertainties implicit in the quantitative mercury analysis
continue to be sufficiently great so as to limit its ultimate use for
decision-making. Therefore, we have used the quantitative analysis to
make qualitative judgments about the risks from mercury but have not
relied on the quantitative analysis (nor do we believe it is
appropriate) to draw quantitative conclusions about the risks
associated with the MACT standards.
D. What Is the Incidence of Adverse Health Effects in the Population?
We estimated the overall risk to human receptor populations for
those chemical constituents that posed the highest individual risks and
whose populations could be enumerated. These included excess cancer
incidence in the general population from the consumption of
agricultural commodities produced in the vicinity of hazardous waste
burning facilities, excess cancer incidence in the local population,
and excess incidence of children with elevated blood lead levels. In
addition, we estimated the avoided incidence of mortality and morbidity
in the local population associated with reductions in exposures to
particulate matter emissions.347 Incidence is generally
expressed in terms of the annual number of new cases of disease in the
exposed population. However, for diseases such as cancer which have a
long latency period, the annual incidence represents the lifetime
incidence associated with an exposure of one year. For diseases with
recurring symptoms, the annual incidence represents the number of
episodes of disease over a year's time.
---------------------------------------------------------------------------
\347\ Excess incidence refers to the incidence of disease beyond
that which would otherwise be observed in the population, absent
exposures to the sources in question. Avoided incidence is the
reduction in incidence of disease in the population that would be
expected from a reduction in exposures to the sources in question.
---------------------------------------------------------------------------
1. Cancer Risk in the General Population
Agricultural commodities produced in the vicinity of hazardous
waste combustors may be consumed by the general population (i.e.,
individuals who reside outside the study area). Commodities such as
meat and milk may be contaminated with dioxins and, therefore, pose
some risk to individuals that consume them. We estimated the amount of
``diet accessible'' dioxin in meat and milk produced at hazardous waste
combustors that would be consumed by the general population and
estimated the number of additional cancer cases that could result from
such exposures. The approach is predicated on the assumption that
cancer risks follow a linear, no-threshold model in the low dose
region.
Our agricultural commodity analysis indicates that, as a result of
today's rule, annual excess cancer incidence in the general population
will be reduced from 0.5 cases per year (90 percent confidence
interval, 0.4 to 0.6) to 0.1 cases per year (90 percent confidence
interval, 0.1 to 0.2). Most of the risk is associated with the
consumption of milk and other dairy products. The combustor categories
that contribute most to the reduction are incinerators with waste heat
recovery boilers and lightweight aggregate kilns.
2. Cancer Risk in the Local Population
Individuals that live and work in the vicinity of hazardous waste
combustors are exposed to a number of compounds that are carcinogenic
by oral or inhalation routes of exposure or both. These include dioxin,
arsenic, beryllium, cadmium, chromium, and nickel. We estimated the
annual cancer incidence in each of the enumerated receptor populations
based on the mean individual risk in each sector and sector-specific
population estimates. The resulting incidence estimates were weighted
using facility-specific sampling weights and summed.
Our analysis of cancer risks in the local population indicates
that, as a result of today's rule, annual excess
[[Page 53008]]
cancer incidence will be reduced from 0.1 cases per year (90 percent
confidence interval, 0.08 to 0.2) to 0.02 cases per year (90 percent
confidence interval, 0.01 to 0.03). Nearly all of the risk reduction,
which occurs almost entirely among non-farm residents, is attributable
to incinerators and results mainly from reductions in emissions of
metals, primarily arsenic, cadmium, and chromium.
3. Risks From Lead Emissions
Children that live near hazardous waste combustor are exposed to
lead emissions through the diet and through inhalation and incidental
soil ingestion. Children that already have elevated blood lead levels
may have their levels further increased as a result of such exposures,
some of whom may have their blood lead levels increased beyond 10
g/dL. We estimated the increase, or excess incidence, of
elevated blood levels above 10 g/dL by estimating the number
of children in each sector with blood lead levels above 10 g/
dL as a result of background exposure and subtracting that from the
number of children above 10 g/dL as a result of both
background exposure and incremental exposures from hazardous waste
combustors. This estimate represents the annual rate of increase in the
number of children with elevated blood lead beyond background.
Our analysis indicates that, as a result of today's rule, the
excess incidence of elevated blood lead will be reduced from 7 cases
per year to less than 0.1 cases per year. The reduction is primarily
attributable to incinerators, although a small reduction (0.4 cases per
year) is attributable to cement kilns. These reductions occur entirely
among non-farm residents. Children of minority and low income
households generally have higher background exposures to lead and are
more likely to have blood levels elevated above 10 g/dL than
children from other demographic groups and, therefore, are more likely
to benefit from reductions in lead exposures. However, our analysis did
not consider the influence of such socioeconomic factors. For this
reason, we believe that we may have underestimated the reductions in
excess incidence of elevated blood lead levels, including potential
reductions attributable to cement kilns and lightweight aggregate
kilns.
4. Risks From Emissions of Particulate Matter
Human epidemiological studies have demonstrated a correlation
between community morbidity and mortality and ambient levels of
particulate matter, particularly fine particulate matter (below 2.5 or
10 microns in diameter, depending on the study), across a wide variety
of geographic settings. Lower particulate matter is associated with
lower mortality, lower rates of hospital admissions, and a lower
incidence of respiratory disease. Concentration-response functions for
various health endpoints have been derived from these studies, and we
used these functions to estimate the reduction in the incidence of
mortality and morbidity associated with a reduction in emissions of
particulate matter.
Our analysis indicates that, as a result of today's rule, there
will be between 1 and 4 fewer premature mortalities per year associated
with particulate matter emissions (depending on which study is used).
In addition, we project there will be 6 fewer hospitalizations, 25
fewer cases of chronic bronchitis, 180 fewer cases of lower respiratory
disease, per year.
The mortality estimates are subject to some uncertainty due to the
fact that the lower estimate (which is derived from long-term studies)
assumes no threshold for effects and the upper estimate (which is
derived from short-term studies) may include mortalities that are
premature by as little as a few days. The no threshold assumption may
be appropriate, however, considering that the reduction in mortality is
projected to occur entirely from incinerators, especially on-site
incinerators. Such incinerators are located at manufacturing facilities
that are likely to have other particulate matter emissions and both on-
site, and commercial incinerators are typically located in industrial
areas where there may be many other sources of particulate matter
emissions, resulting in ambient particulate matter levels that are well
above any threshold. Also, because the particulate matter modeling was
conducted to 20 rather than 50 kilometers, the inhalation risks may be
understated, especially from PM that is 2.5 microns in diameter and
smaller which can be transported over long distances from HWCs.
III. What Is the Potential for Adverse Ecological Effects?
The ecological assessment is based on a screening level analysis in
which model-estimated media concentrations are compared to media-
specific ecotoxicological criteria that are protective of multiple
ecological receptors. The analysis used an ecological hazard quotient
as the metric for assessing ecological risk. The ecological hazard
quotient is the ratio of the model-estimated media concentration to the
ecotoxicological criterion. Hazard quotients above 1 suggest that a
potential for adverse ecological effects may exist. Ecotoxicological
criteria for soils, surface waters, and sediments were used in the
analysis. Ecotoxicological criteria for soil are intended to be broadly
protective of terrestrial ecosystems, including the soil community,
terrestrial plants, and consumers such as mammals and birds.
Ecotoxicological criteria for surface water are intended to be
protective of the aquatic community, including fish and aquatic
invertebrates, primary producers such as algae and aquatic plants, and
fish-eating mammals and birds. Sediment criteria are intended to be
protective of the benthic community. The analysis was conducted for
dioxins, mercury, and fourteen other metals. Only the results for
dioxins and mercury are discussed here. Very low or no potential for
ecological risk was found for the other metals.348 For a
full discussion of the ecological assessment, see the background
document for today's rule.349
---------------------------------------------------------------------------
\348\ Although minor exceedances of the ecotoxicological
criteria for lead were noted for incinerators, the exceedances were
eliminated under today's rule.
\349\ ``Human Health and Ecological Risk Assessment Support to
the Development of Technical Standards for Emissions from Combustion
Units Burning Hazardous Wastes: Background Document--Final Report,''
July, 1999.
---------------------------------------------------------------------------
A. Dioxins
A variation on the general screening level approach was used for
assessing ecological risks from dioxins in surface water. Rather than
basing the assessment on ambient water quality criteria for the
protection of wildlife, ecotoxicological benchmarks for 2,3,7,8-
tetrachlorodibenzo(p)dioxin (TCDD) for fish-eating birds and mammals
(i.e., no observed adverse effects levels) were used to make a direct
comparison with estimated intakes of dioxins in fish in terms of
2,3,7,8-TCDD toxicity equivalents (TEQ). This approach accounts for the
different rates of bioaccumulation of the various 2,3,7,8
dibenzo(p)dioxin and dibenzofuran congeners and avoids the conservatism
of comparing an ambient water quality criterion for 2,3,7,8-TCDD to
model-estimated water concentrations in terms of 2,3,7,8-TCDD TEQs. The
results of our analysis indicate no exceedances of the ecotoxicological
benchmarks for 2,3,7,8-TCDD for any category of hazardous waste
combustors. One limitation of the ecological assessment for dioxins is
that water quality criteria for the protection of aquatic life are not
[[Page 53009]]
available. However, fish and aquatic invertebrates are generally less
sensitive to dioxins than mammals and birds.
For assessing the potential for ecological risk in terrestrial
ecosystems, soil criteria developed for 2,3,7,8-TCDD for the protection
of mammals and birds were compared to model-estimated soil
concentrations in terms of 2,3,7,8-TCDD TEQs. Because the more highly
chlorinated 2,3,7,8 dibenzo(p)dioxin and dibenzofuran congeners are
expected to bioaccumulate in prey species more slowly than 2,3,7,8-
TCDD, the potential for ecological risk is likely to be overstated. Our
analysis indicates that, at baseline, less than one percent of the
study areas surrounding hazardous waste combustors have the potential
for ecological risk from dioxins in soil. Under today's rule, we
project no exceedances of the ecotoxicological criteria for dioxins in
soil. The soil ecotoxicological criterion for dioxins is derived from
studies of reproductive and developmental effects in mammals. Potential
impacts to terrestrial plant and soil communities could not be
evaluated due to a lack of sufficient ecological toxicity data.
However, vertebrates such as mammals and birds are known to be more
sensitive to dioxin exposure than invertebrates. Therefore, we consider
the potential for risk to invertebrate receptors to be low.
B. Mercury
The ecological assessment of mercury is based on water quality
criteria for the protection of wildlife that were developed for the
Mercury Study Report to Congress. The assessment used the lowest of the
available water quality criteria for individual fish-eating avian and
mammalian wildlife species. The frequency distribution of ecological
hazard quotients for total mercury indicates the potential for adverse
ecological effects for cement kilns. Our analysis indicates that, for
cement kilns, exceedances of the ecotoxicological criteria for total
mercury may occur over 40 percent of study area surface waters at
baseline. Above a hazard quotient of 1, the frequency of exceedances
drops off quickly, with hazard quotients above 2 occurring at a
frequency of 1 percent. The ecological hazard quotients remain
essentially unchanged under today's rule. However, we project no
exceedances of the ecotoxicological criteria for methyl mercury.
Because methyl mercury is the form of mercury that is of greatest
concern for fish-eating mammals and birds, the lack of exceedances
suggests that the potential for ecological effects is relatively low.
Our analysis also suggests relatively low potential for ecological
effects for incinerators and lightweight aggregate kilns. Although our
analysis indicates that exceedances of the ecotoxicological criteria
for total mercury may occur over 22 percent of study area surface
waters for lightweight aggregate kilns and 6 percent for incinerators
at baseline, these are reduced to no exceedances and less than 1
percent, respectively, under today's rule. Moreover, we project no
exceedances of the ecotoxicological criteria for methyl mercury. The
significance of these results must be judged in the context of the
considerable uncertainties related to the fate and transport of mercury
in the environment, as discussed elsewhere in today's notice, the
presence of background levels of mercury, and the level of protection
afforded by the underlying ecotoxicological criteria.
For soils, our analysis indicates that less than one percent of the
study areas surrounding hazardous waste combustors have the potential
for ecological risk at baseline. Under today's rule, we project no
exceedances of the ecotoxicological criteria for mercury for
incinerators and lightweight aggregate kilns. For cement kilns, we
project exceedances at a frequency of much less than one percent. The
soil ecotoxicological criterion for mercury is derived from studies of
the reproductive capacity of earthworms. Although earthworms serve a
vital function in the soil community, given the redundancy and
abundance of soil organisms and the low frequency of exceedances, we
believe that adverse impacts to the terrestrial ecosystem, including
higher trophic levels such as terrestrial mammals, are unlikely.
As a screening level analysis, the ecological assessment is subject
to a number of limitations. The analysis assumes the occurrence of the
ecological receptors on which the ecotoxicological criteria are based
in all modeled sectors and water bodies. Although the ecological
receptors included in the analysis are commonly occurring species, they
may not be present in the same locations at which exceedances are
predicted due to a lack of suitable habitat or other factors.
Furthermore, the range of predator and prey species may exceed the
spatial extent of the estimated exceedances. Many primary and secondary
consumers are opportunistic feeders with substantial variability in
both the type of food items consumed as well as the seasonal patterns
of feeding and foraging. These behaviors can be expected to moderate
exposures to chemical contaminants and reduce the potential for risk.
On the other hand, gaps exist in the ecotoxicological data base such
that not all combinations of chemical constituents and ecological
receptors could be evaluated. In addition, media concentrations could
not be estimated for all habitats that may be important to ecological
receptors, such as wetlands. Also, our analysis did not consider the
possible impact of background concentrations. Therefore, although as a
screening level analysis the ecological assessment has a tendency
toward conservatism, we cannot say for certain that no potential exists
for ecological risks that fall beyond the scope of the assessment.
Part Eight: Analytical and Regulatory Requirements
I. Executive Order 12866: Regulatory Planning and Review (58 FR 51735)
Is This a Significant Regulatory Action?
Under Executive Order 12866 (58 FR 51735, October 4, 1993), we must
determine whether a regulatory action is ``significant'' and,
therefore, subject to OMB review and the requirements of the Executive
Order. The Order defines ``significant regulatory action'' as one that
is likely to result in a rule that may:
(1) Have an annual effect on the economy of $100 million or more,
adversely affect in a material way the economy, a sector of the
economy, productivity, competition, jobs, the environment, public
health or safety, or state, local, or tribal governments or
communities;
(2) Create a serious inconsistency or otherwise interfere with an
action taken or planned by another agency;
(3) Materially alter the budgetary impact of entitlement, grants,
user fees, or loan programs or the rights and obligations of recipients
thereof; or
(4) Raise novel legal or policy issues arising out of legal
mandates, the President's priorities, or the principles set forth in
this Executive Order.
Under the terms of Executive Order 12866, we have reviewed today's
rule and determined that it does not represent an ``economically
significant'' regulatory action, as defined under point one above. The
aggregate annualized social costs for this rule are under $100 million
(ranging from $50 to $63 million for the final standards). However, it
has been determined that this rule is a ``significant regulatory
action'' because it may raise novel legal or policy issues (point four
above). As such, this action was submitted to OMB for review. Changes
made in response to OMB suggestions or recommendations will be
documented in the public record.
[[Page 53010]]
We have prepared economic support materials for today's final
action. These documents are entitled: Assessment of the Potential
Costs, Benefits, and Other Impacts of the Hazardous Waste Combustion
MACT Standards--Final Rule, and, Addendum To The Assessment of the
Potential Costs, Benefits, and Other Impacts of the Hazardous Waste
Combustion MACT Standards--Final Rule. The Addendum and Assessment
documents were designed to adhere to analytical requirements
established under the Executive Order, and corresponding Agency and OMB
guidance; subject to data, analytical, and resource limitations.
This part of the Preamble is organized as follows: I. Executive
Order 12866 (as addressed above), II. What Activities have Led to
Today's Rule?--presenting a summary of the analytical methodology and
findings from the 1996 RIA for the proposed action, and, a summary of
substantive peer review and public stakeholder comments on this
document, with Agency responses, III. Why is Today's Rule Needed?--
justifying the need for Federal intervention, IV. What Were The
Regulatory Options?--presenting a brief discussion of the scope of
alternative regulatory options examined, V. What Are the Potential
Costs and Benefits of Today's Rule?--summarizing methodology and
findings from the final Assessment document, VI. What Considerations
Were Given to Issues Like Equity and Children's Health?, VII. Is
Today's Rule Cost-Effective?, VIII. How Do the Costs of Today's Rule
Compare to the Benefits?, IX. What Consideration Was Given to Small
Businesses? X. Were Derived Air Quality and Non-Air Impacts Considered?
XI. Is Today's Rule Subject to Congressional Review?, XII. How is the
Paperwork Reduction Act Considered in Today's Rule?, XIII. Was the
National Technology Transfer and Advancement Act Considered?, and, XIV.
Were Tribal Government Issues Considered? (Executive Order 13084).
The RCRA docket established for today's final rulemaking maintains
a copy of the complete final Assessment and Addendum documents for
public review. Readers interested in these economic support materials
are strongly encouraged to read both documents to ensure full
understanding of the methodology, data, findings, and limitations of
the analysis.
II. What Activities Have Led to Today's Rule?
In May of 1993, we introduced a draft Waste Minimization and
Combustion Strategy designed to reduce reliance on the combustion of
hazardous waste and encourage reduced generation of these wastes. Among
the key objectives of the strategy was the reduction of health and
ecological risks posed by the combustion of hazardous wastes. As part
of this strategy, we initiated the development of MACT emissions
standards for hazardous waste combustion facilities.
On April 19, 1996, we published the proposal, which included
revisions to standards for hazardous waste incinerators and hazardous
waste burning cement kilns and lightweight aggregate kilns. These
proposed MACT standards were designed to address a variety of hazardous
air pollutants, including dioxins/furans, mercury, semivolatile and low
volatile metals, and chlorine. We also proposed to use emissions of
carbon monoxide and hydrocarbons as surrogates for products of
incomplete combustion.
A. What Analyses Were Completed for the Proposal?
We completed an economic analysis in support of the proposal. This
Regulatory Impact Assessment (RIA), examined and compared the costs and
benefits of the proposed standards, as required under Executive Order
12866. Industry economic impacts, environmental justice, waste
minimization incentives, and other impacts were also examined. This RIA
also fulfilled the requirements of the Regulatory Flexibility Act by
evaluating the effects of regulations on small entities. This document,
Regulatory Impact Assessment for Proposed Hazardous Waste Combustion
MACT Standards (November 13, 1995), Appendices (November 13, 1995), and
two Addenda (November 13, 1995 and February 12, 1996) are available in
the docket established for the proposed action.
Throughout the development of the proposal, we considered many
alternative regulatory options. A full discussion of the methodology
and findings of all options considered is in the Regulatory Impact
Assessment (RIA). Only the floor option and our preferred option (i.e.,
the floor option and beyond-the-floor options for selected hazardous
air pollutants) are discussed in this summary.
1. Costs
To develop industry compliance cost estimates, we categorized or
modeled combustion units based on source category and size and
estimated engineering costs for the air pollution control devices
needed to achieve the proposed standards. Based on current emissions
and air pollution control device information, we developed assumptions
regarding the type of upgrades that units would require. This ``model
plants'' engineering cost analysis was used because our data were
limited.
Total annual compliance cost estimates for the floor option and the
beyond-the-floor standards ranged from $93 million to $136 million,
respectively, beyond the baseline. For the floor option, on-site
incinerators represented 55 percent of total nationwide costs, cement
kilns represented 29 percent, commercial incinerators represented 14
percent, and lightweight aggregate kilns represented 2 percent. Of the
total beyond-the-floor costs, on-site incinerators represented 50
percent, cement kilns represented 32 percent, commercial incinerators
represented 15 percent, and lightweight aggregate kilns represented 3
percent. For the incremental impacts of going from the floor to beyond-
the-floor, lightweight aggregate kilns were projected to experience a
100 percent increase in compliance costs, cement kilns would experience
a 63 percent increase, commercial incinerators and on'site
incinerators, at 54 and 34 percent, respectively. Overall, compliance
costs associated with the proposed action were projected to result in
significant economic impacts to the combustion industry.
The RIA also examined average total annual compliance costs per
combustion unit. This indicator was designed to assess the relative
impact of the rule on each facility type in the combustion universe.
Findings projected that cement kilns were likely to incur the greatest
average incremental cost per unit, totaling $770,000 annually at the
floor and $1.1 million annually for the proposed beyond-the-floor
standards. The costs for LWAKs ranged from $490,000 to $825,000. The
costs for on-site incinerators ranged from $340,000 to $486,000. The
costs for commercial incinerators ranged from $493,000 to $730,000.
These costs assume no market exits. Once market exit occurs, average
per unit costs may be significantly lower, particularly for on-site
incinerators.
The analysis also examined the floor and proposed beyond-the-floor
impacts on a per ton basis. In the baseline, average prices charged to
burn hazardous waste were estimated to be $178 per ton for cement
kilns, $188 per ton for lightweight aggregate kilns, $646 per ton for
commercial incinerators, and $580 per ton for on-site incinerators
(approximate internal transfer price).
[[Page 53011]]
Baseline burn costs (before consolidation) for these facilities were
found to average $104 per ton for cement kilns, $194 per ton for
lightweight aggregate kilns, $806 per ton for commercial incinerators,
and $28,460 per ton for on-site incinerators. 350
Incremental compliance costs at the floor and proposed BTF levels were
estimated to be $23 to $31 per ton for commercial incinerators, $40 to
$50 per ton for cement kilns, $39 to $56 per ton for lightweight
aggregate kilns, and $47 to $57 per ton for on-site incinerators.
---------------------------------------------------------------------------
\350\ Baseline costs were calculated by identifying all costs of
hazardous waste burning. For commercial incinerators and on-site
incinerators, all costs of construction, operation and maintenance
are included. This also includes RCRA permits and existing air
pollution control devices. The costs for on-site burners are
extremely high because the costs are distributed across the small
amount of hazardous waste burned. For cement kilns and lightweight
aggregate kilns, only the incremental costs of with burning
hazardous waste are included (e.g., permits). The cost of the actual
units (which are primarily for producing cement or aggregate) are
not included in the baseline.
---------------------------------------------------------------------------
From comparison of these prices and baseline burn costs, some high-
cost facilities, especially commercial and on-site incinerators,
appeared to be burning below break-even levels. The incremental
compliance costs of the proposal would make these facilities even less
competitive. The RIA estimated that, of the facilities which are
currently burning hazardous waste, three cement kilns, two lightweight
aggregate kilns, six commercial incinerators, and eighty-two on-site
incinerators would likely stop burning hazardous waste over the long
term. These were incremental to projected baseline market exits
estimated at the time of proposal. Most of the facilities that exit the
market were ones that burned smaller amounts of hazardous waste.
We also conducted a generalized cost effectiveness analysis for the
proposal. We found that the cost per hazardous air pollutant is often
difficult to estimate because the air pollution control devices often
control more than one pollutant. Therefore, it was not feasible to
estimate precise costs per pollutant. Once the compliance expenditures
had been estimated, the total mass emission reduction achieved when
facilities comply with the standards option was estimated. The total
incremental cost per incremental reduction in pollutant emissions was
then estimated. Considering all facilities together, dioxin, mercury,
and metals costs per unit reduction are quite high because small
amounts of the dioxin and metals are released into the environment. For
other pollutants, expenditures per ton are much lower. Please refer to
the November 13, 1995 draft RIA for a complete discussion of the
methodology and findings.
2. Benefits
Our evaluation showed that background levels of dioxin in beef,
milk, pork, chicken, and eggs were approximately 0.50, 0.07, 0.30,
0.20, and 0.10 parts per trillion fresh weight, respectively, on a
toxicity equivalent (TEQ) basis. These background levels and
information on food consumption were then used to estimate dietary
intake in the general population. That estimate was 120 picograms TEQ
per day. We also collected background data on dioxins in fish, taken
from 388 locations nationwide. At 89 percent of the locations, fish
contained detectable levels of at least two of the dioxin and furan
compounds for which analyses were conducted. We then estimated total
dioxin emissions from hazardous waste combustors at 0.94 kg TEQ per
year. This represented about 9 percent of total anthropogenic emissions
of dioxins in the U.S. at the time. The dioxin estimates have been
revised since then.
While no one-to-one relationship between emissions and risk exists,
it was inferred that hazardous waste-burning sources were likely to
contribute significantly to dioxin levels in foods. In the proposal, we
estimated that these dioxin emissions would be reduced to 0.07 kg TEQ
per year at the floor levels and to 0.01 kg TEQ per year at the beyond
the floor levels. We estimated this to result in decreases of
approximately 8 and 9 percent in total estimated anthropogenic U.S.
emissions, respectively. Our position at proposal was that reductions
in these emissions, in conjunction with reductions from other dioxin-
emitting sources, would help reduce dioxin levels in foods over time
and, therefore, reduce the likelihood of adverse health effects,
including cancer.
Mercury is a concern in both occupational and environmental
settings. Human exposures to methyl mercury occur primarily from
ingestion of fish. Mercury contamination results in routine fish
consumption bans or advisories in over two thirds of the States. At the
proposal, we estimated a safe exposure level to methyl mercury (the
reference dose) at 0.0001 mg per kg per day. We collected data on
chemical residues in fish from 388 locations nationwide and found that
fish contained detectable levels of mercury at 92 percent of the
locations. Similar results have been obtained in other studies,
strongly suggesting that long-range atmospheric transport and
deposition of anthropogenic emissions is occurring. Our research found
that, for persons who eat significant amounts of freshwater fish,
exposures to mercury may be significant compared to the threshold at
which effects may occur in susceptible individuals.
Our estimates for the proposal indicated that hazardous waste
combustors emitted a total of 10.1 Mg of mercury per year, representing
about 4 percent of the U.S. anthropogenic total. Implementation of the
floor levels were estimated to reduce mercury emissions from all
hazardous waste-burning sources to 3.3 Mg per year. The proposed
beyond-the-floor levels would drop this to an estimated 2.0 Mg per
year. Such reductions were estimated to lower total anthropogenic U.S.
emissions by approximately 3 percent. Reductions in these mercury
emissions, in conjunction with the Agency's efforts to reduce emissions
from other mercury-emitting sources, would help diminish mercury levels
in fish over time and, therefore, reduce the likelihood of adverse
health effects occurring in fish-consuming populations.
Other benefits we investigated for the proposal included ecological
benefits, property value benefits, soiling and material damage,
aesthetic damages, and recreational and commercial fishing impacts.
Overall, the analysis of the ecological risk suggested that water
quality criteria may be exceeded only in small watersheds located near
waste combustion facilities. Furthermore, such exceedances would occur
only when assuming very high emissions. The preliminary analysis for
the proposal indicated that property value impacts may be very
significant because of emission reductions from hazardous waste
combustion facilities. A detailed review of this analysis, as well as
other benefits (e.g., avoided clean-up as result of reduced particulate
matter releases), is presented in chapter 5 of the November 13, 1995
Regulatory Impact Assessment.
3. Other Regulatory Issues
We also examined other issues associated with the proposal. These
included environmental justice, unfunded federal mandates, regulatory
takings, and waste minimization.
a. Environmental Justice. We completed an analysis of demographic
characteristics of populations near cement plants and commercial
hazardous waste incinerators and compared them to county and state
populations. This analysis focused on spatial relationships between
these
[[Page 53012]]
facilities and the adjacent minority and low income populations. The
study did not describe the actual health status of these populations
nor how their health might be affected in proximity to hazardous waste
facilities. Results indicated that 27 percent of all cement plants and
37 percent of the sample of incinerators had minority percentages
within a one mile radius which exceed the corresponding county minority
percentages by more than five percentage points. Eighteen percent of
all cement plants and 36 percent of the sample of incinerators had
poverty percentages which exceed the county poverty percentages by more
than five percentage points. Please see chapter seven of the November
13, 1995 RIA for a full discussion of the environmental justice
methodology and findings conducted for the proposal.
b. Unfunded Federal Mandates. Our analysis of compliance with the
Unfunded Mandates Reform Act (UMRA) of 1995 found that the proposal
contained no State, local, tribal government, or private sector Federal
mandates as defined under the regulatory provisions of Title II of
UMRA. We concluded that the rule implements requirements specifically
set forth by Congress, as stated in the CAA and RCRA. The proposed
standards were not projected to result in mandated annualized costs of
$100 million or more to any state, local, or tribal government.
Furthermore, the proposed standards would not significantly or uniquely
affect small governments.
c. Regulatory Takings. We found no indication that the proposed
MACT standards would be considered a taking, as defined by legislation
being considered by Congress at the time. Property would not be
physically invaded or taken for public use without the consent of the
owner. Also, the proposed standards would not deprive property owners
of economically beneficial or productive use of their property or
reduce the property's value.
d. Incentives for Waste Minimization and Pollution Prevention. We
briefly examined the potential for waste minimization in the proposal.
Preliminary results suggested that generators have a number of options
for reducing or eliminating waste. To evaluate whether facilities would
adopt applicable waste minimization measures, a simplified pay back
analysis was used. Using information on per-facility capital costs for
each technology, we estimated the time period required for the cost of
the waste minimization measure to be returned in reduced combustion
expenditures. Our assessment of waste minimization found that
approximately 630,000 tons of waste may be amenable to waste
minimization. For a complete description of the analysis please see the
November 13, 1995 Regulatory Impact Assessment.
4. Small Entity Impacts
The Regulatory Flexibility Act (RFA) of 1980 requires Federal
agencies to consider impacts on small entities throughout the
regulatory process. Section 603 of the RFA calls for an initial
screening analysis to determine whether small entities will be
adversely affected by the regulation. If affected small entities are
identified, regulatory alternatives must be considered to mitigate the
potential impacts. Small entities, as described by the Act, are only
those ``businesses, organizations, and governmental jurisdictions
subject to regulation.'' We used information from Dunn & Bradstreet,
the American Business Directory, and other sources to identify small
businesses. Based on the number of employees and annual sales
information, we identified eleven firms which might be considered
directly affected small entities. We found that directly affected small
entities were unlikely to be significantly affected and that over one-
third of those that were considered small, while having a relatively
small number of employees, had annual sales in excess of $50 million
per year. Also, small entities impacted by the proposal were found to
be those that burn very little waste and hence face very high cost per
ton burned. These facilities were expected to discontinue burning
hazardous waste rather than complying with the proposal. These costs of
discontinuing waste burning would not be so high as to be a significant
impact. Thus, we found that the proposal may, at most, have a minor
impact on a limited number of affected small businesses.
B. What Major Comments Were Received on the Proposal RIA?
The November 13, 1995 Regulatory Impact Assessment (RIA) received
comment from many concerned stakeholders. We also conducted a formal
peer review of the RIA. We appreciate all comments received and
incorporated many of the suggestions into the final Assessment document
to improve the analysis. A summary of the key issues presented by
stakeholders and the peer reviewers is presented below, along with our
responses. You are requested to review the complete documents: Comment
Response Document--Addressing The Public Comments Received On:
Regulatory Impact Assessment for Proposed Hazardous Waste Combustion
MACT Standards, Draft, November 13, 1995, and, Peer Review Response
Document--Addressing The Peer Review Received On: Regulatory Impact
Assessment for Proposed Hazardous Waste Combustion MACT Standards,
Draft, November 13, 1995. These documents, available in the RCRA docket
established for today's action, present complete responses to all
substantive comments received on the 1995 RIA.
1. Public Comments
We received several general comments on the accuracy of the
baseline and compliance costs applied in the RIA. Several commenters
suggested that we revise baseline and compliance costs to improve their
accuracy, which we did. Instead of using a model plant approach for
assigning compliance and baseline costs to modeled combustion
facilities, costs for today's rule have been estimated using combustion
system-specific parameters including gas flow rate, baseline emissions,
air pollution control devices currently in place, total chlorine in
feed, stack moisture, and temperature at the inlet to the air pollution
control device. These system-specific baseline and compliance costs
allow for greater accuracy in estimating national costs and predicting
which facilities are likely to stop burning hazardous waste. Also, the
baseline costs include clinker production penalties at cement kilns and
use updated incinerator capital costs, labor requirements, and ash
disposal costs.
Various commenters were concerned that the consolidation routine in
the economic modeling was unrealistic. For the final economic
assessment, we revised the consolidation routine to incorporate
capacity constraints that affect the ability of combustion facilities
to consolidate wastes into fewer systems at a given facility. Maximum
capacity rates (tons per year) were derived by using the feed rates in
OSW's database (pounds per year) and assuming 8,000 hours per year of
operation. Wastes are assumed to be consolidated into fewer combustion
systems at a single facility to the extent that the capacity
constraints allow the systems to absorb the displaced hazardous wastes.
Many commenters felt that the waste minimization analysis of the
1995 RIA was unrealistic and overestimated gains. They suggested that
the waste minimization analysis be improved to reflect other
constraints faced by waste generators. For the 1999 Assessment, we
conducted an expanded and significantly improved analysis of waste
[[Page 53013]]
minimization alternatives, using a more detailed decision framework for
evaluating waste minimization investment decisions. This framework
attempts to capture the full inventory of costs, savings, and revenues,
including indirect, less tangible items typically omitted from waste
minimization analysis, such as liability and corporate image. For each
alternative that was identified as viable for currently combusted waste
streams, cost curves were developed for a range of waste quantities, as
cost varies by waste quantity. These cost curves were then used to
determine whether a waste generator would shift from combustion to
waste minimization alternatives as combustion prices rise.
Some commenters suggested that we model waste markets to reflect
segmentation across waste types, instead of simply applying different
prices for kilns and incinerators. In response, we have developed a
revised pricing approach that covers seven categories of waste types
and prices. The economic model used for the 1999 Assessment
incorporates these seven different waste types and prices. Waste
management prices depend on several factors: Waste form (solid/liquid/
sludge), heat content, method of delivery (e.g., bulk versus drum), and
contamination level (e.g., metals or chlorine content). In addition,
regulatory constraints (e.g., prohibitions against burning certain
types of wastes) and technical constraints (e.g., adverse effects of
certain waste streams on cement product quality) also influence
combustion prices. Although data limitations prevent the inclusion of
all factors, the information on heat content and constituent
concentrations from EPA's National Hazardous Waste Constituent Survey
(NHWCS) allowed us to enhance the characterization of combusted waste.
A few commenters indicated that the baseline costs of waste burning
for cement kilns should include the shared joint costs of cement
production. We do not include cement production costs in the costs of
waste burning because they are not part of the incremental costs
introduced by hazardous waste burning at kilns. We believe this
assumption is appropriate, given that cement production is the
principal activity of cement kilns that burn hazardous waste.
Furthermore, that same kiln would be required in the production of
cement regardless of hazardous waste combustion activities. We did,
however, evaluate whether some of the more economical marginal kilns
may be covering cement production costs with hazardous waste burning
revenues. These findings are reported in the 1999 Assessment document.
Some were concerned that shutdown costs and environmental risks
associated with combustion facility closures were not accounted for in
the 1995 economic analysis. We found that many of the facilities that
are expected to close are those that are were operating significantly
below capacity in the baseline. This suggests that such facilities may
not have been fully recovering their capital costs and are likely to
close, even in the absence of the MACT standards. Therefore, while
closure is not costless, closure costs attributable directly to the
MACT standards are likely to be relatively small. With regard to
increased risks from transportation of hazardous wastes, the
incremental health risks will be minimal since these facilities are
burning small quantities of waste. In fact, we estimate that less than
1.5 percent of the wastes currently burned at combustion facilities
will be reallocated due to facility closure. Moreover, spills and other
accidents caused by trucking hazardous waste (the most common means of
shipment for hazardous materials) generally are considered low-
probability events, especially relative to the total number of
accidents occurring within transportation overall.
Some commenters felt that potential impacts on generators and fuel
blenders were not adequately addressed. In the 1995 RIA, we considered
these costs and determined that hazardous waste generators and fuel
blenders would likely see price increases for combusted waste streams,
though the magnitude of the price increase will depend on the type of
waste and the non-combustion waste management alternatives available
for that waste type. The price increase faced by generators was
estimated at 10 percent of market prices.
The major hazardous waste burning sectors frequently presented
alternative views regarding various key waste burning issues. These
included: Facility market exits, revenues, impacts resulting from waste
feedrate modifications, impacts from alternative fuel usage, price
impacts, and available practical capacity. We have reviewed and
evaluated the substantiative information submitted by all concerned
stakeholders and believe our final Assessment and Addendum documents
reflect a fair and balanced representation of baseline conditions and
post-rule incremental economic impacts.
2. Peer Review
The peer reviewers suggested that we clarify the aims, objectives,
and organizing principles for the 1995 RIA. They stated that, while the
1995 RIA generally meets the requirements set forth by OMB's Guidance
regarding the economic analysis of federal regulations under Executive
Order 12866, the RIA would be substantially improved if it fully
conformed with OMB's Guidance, especially with regard to organization
and statement of objectives. For the 1999 Assessment, we have tried to
restructure the document to be more in line with OMB's 1996 Guidance
for conducting Economic Analysis of Federal Regulations Under Executive
Order 12866. The 1999 Assessment includes the following elements in the
first chapter to address concerns of the reviewers: the objectives of
the Economic Assessment, the analytical requirements the document
fulfills, the rationale for regulatory action, an examination of
alternative regulatory options, the anticipated effect of the MACT
standards, and the analytic approach and organization for the
subsequent chapters.
The peer reviewers also suggested that the compliance costs need to
be clearly distinguished from social costs, as defined by the theory of
applied welfare economics. For the 1999 Assessment, we have been
careful to clarify the difference between compliance costs and social
costs and explain how the rule will likely affect producers and
consumers. The final Assessment explicitly lays out the economic
framework for the social cost analysis and distinguishes these from
compliance cost estimates. The hazardous waste combustion market is
diverse, dynamic, and segmented. Because data are not adequate to
support a full econometric analysis at this level of complexity, we
have applied a simplified approach that brackets the welfare loss
attributable to today's rule. This approach bounds potential economic
welfare losses by considering two scenarios: (1) Compliance costs
assuming no market adjustments (the upper bound) and (2) market
adjusted compliance costs (the lower bound).
The peer reviewers also suggested that the benefits analysis was
not fully responsive to the requirements of Executive Order 12866. For
the 1999 Assessment, we have applied results from an extensive multi-
pathway risk assessment to develop human health and ecological benefit
estimates. For the human health analysis, benefits are estimated from
cancer and noncancer
[[Page 53014]]
risk reductions. Cancer risk reduction estimates are monetized by
applying the value of a statistical life (VSL) to the risk reduction
expected to result from the MACT standards. Monetary values are
assigned to noncancer benefits using a direct-cost approach which
focuses on the expenditures averted by decreasing the occurrence of an
illness or other health effect. Ecological benefits are also included
in the 1999 Assessment.
The peer reviewers suggested that easily burned waste streams would
command lower prices and that this should be reflected in the economic
modeling. They also indicated that certain combustion sectors may only
handle these easy-to-burn waste types and that this should be reflected
in baseline costs for these combustors. The pricing approach used in
the 1999 Assessment assigns different prices to different types of
wastes. Waste management prices depend on several factors, which
include: waste form (solid/liquid/sludge), heat content, method of
delivery (e.g., bulk versus drum), and contamination level (e.g.,
metals or chlorine content). In addition, regulatory constraints (e.g.,
prohibitions against burning certain types of wastes) and technical
constraints (e.g., adverse effects of certain waste streams on cement
product quality) also influence combustion prices. Although data
limitations prevent us from accounting for all factors, the information
on heat content and constituent concentrations from EPA's National
Hazardous Waste Constituent Survey (NHWCS) allowed us to enhance the
characterization of combusted waste. In addition to pricing
refinements, the 1999 Assessment adjusts baseline costs to reflect
differences in the performance and capabilities across combustion
systems.
The peer reviewers were also concerned that the 1995 RIA applied
outdated data in the analysis. The most recent available data were used
in the 1995 RIA. The 1999 Assessment, once again, applies the most
recently available, and verified data.
The peer reviewers suggested that fully-loaded cost-per-ton
estimates should be provided for each waste minimization alternative so
that these could be compared with combustion prices. For the 1999
Assessment, we conducted an expanded and significantly improved
analysis of waste minimization alternatives. This analysis used a more
detailed decision framework for evaluating waste minimization
investment decisions that captures the full inventory of costs,
savings, and revenues, including indirect, less tangible items
typically omitted from waste minimization analysis, such as liability
and corporate image. For each viable waste minimization alternative for
currently combusted waste streams, cost curves were developed for a
range of waste quantities because cost varies by waste quantity. These
cost curves were then used to determine whether a waste generator would
shift from combustion to waste minimization alternatives as combustion
prices rise.
III. Why Is Today's Rule Needed?
Today's rule will reduce the level of several hazardous air
pollutants, including dioxins and furans, mercury, semi-volatile and
low volatile metals, and chlorine gas. Carbon monoxide, hydrocarbons,
and particulate matter will also be reduced. Most hazardous waste
combustion facilities are currently operating with some air pollution
control devices in place. However, existing pollutants from these
facilities are still emitted at levels found to result in risks to
human health and the environment. Human exposure to these combustion
air toxics occurs both directly and indirectly and leads to cancer,
respiratory diseases, and possibly developmental abnormalities. A
preliminary screening analysis suggests that ecosystems are also at
risk from these air pollutants.
The hazardous waste combustion industry operates in a dynamic
market. Several combustion facilities and systems have closed or
consolidated over the past several years and this trend is likely to
continue. These closures and consolidations may lead to reduced air
pollution, in the aggregate, from hazardous waste facilities. However,
the ongoing demand for hazardous waste combustion services will
ultimately result in a steady equilibrium as the market adjusts over
the long-term. We therefore expect that air pollution problems from
these facilities, and the corresponding threats to human health and
ecological receptors, will continue if today's rule were not
implemented.
The market has generally failed to correct the air pollution
problems resulting from the combustion of hazardous wastes. This has
occurred for several reasons. First, there exists no natural market
incentive for hazardous waste combustion facilities to incur additional
costs implementing control measures because the individuals and
entities who bear the negative human health and ecological impacts
associated with these actions have no direct control over waste burning
decisions. This may be referred to as an environmental externality,
where the private industry costs of combustion do not fully reflect the
human health and environmental costs of hazardous waste combustion.
Second, the parties injured by the combusted pollutants are not likely
to have the resources or technological expertise to seek compensation
from the damaging entity (combustion facility) through legal or other
means. Finally, emissions from hazardous waste combustion facilities
directly affect a ``public good,'' the air. Improved air quality
benefits human health and the environment. These benefits cannot be
limited to just those who pay for reduced pollution. The absence of
government intervention, therefore, will result in a free market that
does not provide the socially optimal quantity and quality of public
goods, such as air.
We recognize the need for federal regulation as the optimal means
of correcting market failures leading to the negative environmental
externalities resulting from the combustion of hazardous waste. The
complex nature of the pollutants, waste feeds, waste generators, and
the diverse nature of the combustion market would limit the
effectiveness of a non-regulatory approach such as taxes, fees, or an
educational-outreach program. Furthermore, requirements for MACT
standards under the Clean Air Act, as mandated by Congress, has
compelled us to select today's regulatory approach.
IV. What Were the Regulatory Options?
We carefully assembled and evaluated all data and relevant
information acquired since the proposal. We considered several
alternative MACT options since the proposal, ultimately leading to
today's rule. Please refer to Part Four of this preamble for more
detail on option development and the specific approach and methodology
used in developing the final standards. This section of today's
preamble briefly discusses and assesses the final regulatory levels and
two primary options. The final regulatory levels, as discussed in Part
Four, establish a combination of floor and beyond-the-floor standards
for the pollutants of concern. Of the options analyzed, one addresses a
floor only scenario and the other examines beyond-the-floor levels for
dioxins/furans and mercury, based on activated carbon injection (ACI).
The reader may wish to examine the Assessment document for a complete
discussion of the analytical methodology, costs, benefits, and other
projected impacts of today's rule and options. This Assessment document
is available in the RCRA docket for today's rule.
[[Page 53015]]
V. What Are the Potential Costs and Benefits of Today's Rule?
A. Introduction
The value of any regulatory policy is traditionally measured by the
net change in social welfare that it generates. Our economic assessment
for today's rule evaluates costs, benefits, economic impacts, and other
impacts such as environmental justice, children's health, unfunded
mandates, waste minimization incentives, and small entity impacts. To
conduct this analysis, we examined the current combustion market and
practices, developed and implemented a methodology for examining
compliance and social costs, applied an economic model to analyze
industry economic impacts, quantified (and, where possible, monetized)
benefits, and followed appropriate guidelines and procedures for
examining equity considerations, children's health, and other impacts.
The data we used in this analysis were the most recently available at
the time of the analysis. Data verification, relevance, and public
disclosure issues prevented us from incorporating data from certain
sources. Furthermore, because our data were limited, the estimated
findings from these analyses should be viewed as national, not site
specific impacts.
B. Combustion Market Overview
The hazardous waste industry comprises three key segments:
hazardous waste generators, fuel blenders and intermediaries, and
hazardous waste incinerators. Hazardous waste is combusted at three
main types of facilities: Commercial incinerators, on-site
incinerators, and waste burning kilns (cement kilns and lightweight
aggregate kilns). Commercial incinerators are generally larger in size
and designed to manage virtually all types of solids, as well as liquid
wastes. On-site incinerators are more often designed as liquid-
injection systems that handle liquids and pumpable solids. Waste
burning kilns burn hazardous wastes to generate heat and power for
their manufacturing processes.
As of the date of our analysis, 172 combustion facilities are
permitted to burn hazardous waste in the United States. On-site
incinerators (private and government) represent 129 facilities (or 75
percent of this total), commercial incinerators represent 20
facilities, cement kilns represent 18 facilities, and lightweight
aggregate kilns represent five facilities. A facility may have one or
more combustion systems. Companies that generate large quantities of
uniform hazardous wastes generally find it more economical and
efficient to combust these wastes on-site using their own noncommercial
systems. Commercial incineration facilities manage a wide range of
waste streams generated in small to medium quantities by diverse
industries. Cement kilns and lightweight aggregate kilns derive heat
and energy by combining clean burning (solvents and organics) high-Btu
liquid hazardous wastes with conventional fuels. The EPA Biennial
Reporting System (BRS) reports a total demand for all combusted
hazardous waste, across all three types of facilities, at nearly 3.3
million tons in 1995.
Most of the waste managed by combustion comes from a relatively
narrow set of industries. The entire chemical industry in 1995
generated 74 percent of all combusted waste. Within this sector, the
organic chemicals subsector was the largest source of waste sent to
combustion, providing about 32 percent of all combusted waste. The
pesticide and agricultural chemical industry generated 12 percent of
the total. No other single sector generated more than 10 percent of the
total.
Regulatory requirements, liability concerns, and economics
influence the demand for combustion services. Regulatory forces
influence the demand for combustion by mandating certain hazardous
waste treatment standards (land disposal restriction requirements,
etc.). Liability concerns of waste generators affect combustion demand
because combustion, by destroying organic wastes, greatly reduces the
risk of future environmental problems. Finally, if alternative waste
management options are more expensive, hazardous waste generators will
likely choose to send their wastes to combustion facilities in order to
increase their overall profitability.
Throughout much of the 1980s, hazardous waste combustors enjoyed a
strong competitive position and generally maintained a high level of
profitability. During this period, EPA regulations requiring combustion
greatly expanded the waste tonnage for this market. In addition,
federal permitting requirements, as well as powerful local opposition
to siting of new incinerators, constrained the entry of new combustion
systems. As a result, combustion prices rose steadily, ultimately
reaching record levels in 1987. The high profits of the late 1980s
induced many firms to enter the market, in spite of the difficulties
and delays anticipated in the permitting and siting process. Hazardous
waste markets have changed significantly since the late 1980s. In the
early 1990s, substantial overcapacity resulted in fierce competition,
declining prices, poor financial performance, numerous project
cancellations, and some facility closures. Since the mid 1990s, several
additional combustion facilities have closed, while many of those that
have remained open have consolidated their operations. There still
remains significant overcapacity throughout the hazardous waste
combustion industry.
C. Baseline Specification
Proper and consistent baseline specification is vital to the
accurate assessment of incremental costs, benefits, and other economic
impacts associated with today's rule. The baseline essentially
describes the world absent today's rule. The incremental impacts of
today's rule are evaluated by predicting post MACT compliance responses
with respect to the baseline. The baseline, as applied in this
analysis, is the point at which today's rule is promulgated. We
recognize that the baseline should not simply describe a point in time,
but rather should describe the state of the world over time, absent
today's rule. The Assessment describes the data sources used in
specifying the baseline and examines how each of these factors are
likely to change over time in the absence of today's rule. Finally,
because this analysis precedes final rule promulgation, data sources
used to determine the baseline will necessarily predate the point of
rule promulgation. A full discussion of baseline specification is
presented in the Assessment document for today's rule.
D. Analytical Methodology and Findings--Engineering Compliance Cost
Analysis
The total compliance costs for existing hazardous waste combustion
facilities are developed using engineering models that assign pollution
control measures and costs to each modeled combustion system. The
engineering model also incorporates other compliance costs, such as
monitoring requirements, permit modifications, sampling and analyses,
and other recordkeeping and reporting requirements. We applied the same
basic approach in developing compliance costs for new sources as was
used for existing sources. Please see the Assessment document for a
complete discussion of the analytical methodology applied for existing
and new facilities.
Compliance costs presented in this section are based on a static
analysis assuming no market adjustments.
[[Page 53016]]
Results from this static analysis should therefore be considered
``high-end'' estimates. The engineering compliance cost analysis
reveals that each combustion system will likely comply with the final
standards through a different combination of pollution control
measures. This is likely to result in widely diverse per system
compliance costs across combustion sectors. The average annualized per
system costs, across all sectors, are projected to range from about
$0.16 to $0.72 million for compliance with the final standards. Per
system costs at the floor are estimated to range from $0.16 to $0.68
million, while these costs under the beyond-the-floor activated carbon
injection (ACI) option would range from $0.36 to $0.99 million. Cement
kilns were generally found to experience the highest per system
compliance costs, while the commercial and on-site incinerators would
generally experience the lowest per system costs. The compliance costs
per ton of hazardous waste burned are projected to increase from 31 to
41 percent for cement kilns and about 35 percent for lightweight
aggregate kilns. The increase for commercial incinerators is estimated
at 20 percent of the baseline burn costs. The regulated community is
also likely to experience some cost savings as a result of the
streamlined administrative procedures established through today's final
rule.
The compliance cost analysis contains a variety of uncertainties.
The most significant include: The limited availability of emissions
data upon which engineering controls are based, lack of baseline air
pollution control device data for a number of facilities, and the
difficulty in determining the extent to which feed control may be used
as a feasible alternative method of compliance. While uncertainties are
acknowledged, we do not believe that the above data limitations
significantly bias the results either upward or downward.
In addition to costs incurred by the private sector, today's rule
is also likely to result in incremental costs and savings to government
regulatory entities at different levels as they administer and enforce
the new emissions standards and related requirements. EPA Regional
offices, state agencies, as well as some local agencies may incur some
combination of incremental costs associated with permitting.
Modifications of the permitting process related to Clean Air Act
provisions could cost governmental entities, nationwide, approximately
$330,000 per year. Potential government activities could also include
the state rulemaking efforts necessary for agencies to modify their
RCRA permitting processes as part of the ``Fast-Track'' provisions.
State rulemakings and authorization of the modified procedures could
cost states between $500,000 and $700,000, nationwide. Streamlined RCRA
permit modification procedures may also result in aggregate savings
ranging from $0.4 to $2.1 million. Overall economic impacts on
particular governmental regulatory entities will depend on a variety of
factors that are difficult to characterize with precision. Furthermore,
economic impacts associated with governmental activities will differ in
the way in which a particular governmental entity may choose to
implement the requirements.
E. Analytical Methodology and Findings--Social Cost Analysis
We examined social cost impacts potentially associated with today's
rule. Total social costs include the value of resources used to comply
with the standards by the private sector, the value of resources used
to administer the regulation by the government, and the value of output
lost due to shifts of resources to less productive uses. To evaluate
these shifts in resources and changes in output requires predicting
changes in behavior by all affected parties in response to the
regulation, including responses of directly-affected entities, as well
as indirectly-affected private parties.
For this analysis, social costs are grouped into two categories:
economic welfare (changes in consumer and producer surplus), and
government administrative costs. The economic welfare analysis
conducted for today's rule uses a simplified partial equilibrium
approach to estimate social costs. In this analysis, changes in
economic welfare are measured by summing the changes in consumer and
producer surplus. This simplified approach bounds potential economic
welfare losses associated with the rule by considering two scenarios:
Compliance costs assuming no market adjustments, and market adjusted
compliance costs.
Social costs presented in this section assume market adjustments.
Under this scenario, increased compliance costs are examined in the
context of likely incentives combustion facilities would have to
continue burning hazardous wastes and the competitive balance in
different combustion sectors. Furthermore, combustion facilities are
likely to try to recover these increased costs by charging higher
prices to generators and fuel blenders. This scenario estimates market
adjusted compliance costs by assessing baseline profitability,
profitability post-rule using different price increase scenarios, and
waste management alternatives in order to help predict combustion price
increases.
Overall, the difference in aggregate compliance costs for all
sectors of the existing regulated community to meet any of the examined
scenarios is not substantial. Total annualized market adjusted costs
for all sectors are estimated to range from $44 to $50 million under
the floor option. Under the beyond-the-floor (ACI) option, these costs
are estimated to range from $98 to $107 million. For all sectors to
meet the final standards, our best estimate of total annualized costs
ranges from $50 to $63 million, depending upon level of price pass-
through. All cost estimates are incremental to the baseline. These
estimates, however, are not incremental to any mutual requirements
potentially associated with cement kilns meeting standards established
under the nonhazardous waste burner cement kiln rule.
Cement kilns ($17-24 million) and private on-site incinerators
($20-24 million) make up about 76 percent of aggregate national costs
under the final standards. For cement kilns, this is due primarily to
the high costs per system. For private on-site incinerators, the high
costs are primarily due to the large number of combustion systems.
Total costs are less for commercial incinerators ($5-6 million, or 10
percent) because of lower costs per system relative to cement kilns and
due to the limited number of commercial units relative to on-site
incinerators. Lightweight aggregate kilns ($3 million) represent about
5 to 6 percent of the total costs, due primarily to the limited number
of units. Government on-site units make up the remainder.
F. Analytical Methodology and Findings--Economic Impact Analysis
Various market adjustments are expected in response to the
increased costs of hazardous waste combustion associated with today's
rule. Economic impacts may be measured through numerous factors. This
analysis examines market exit estimates, waste reallocations,
employment impacts, combustion price increases, industry impacts, and
the multirule or joint impacts analysis. Economic impacts presented in
this section are distinct from the social costs analysis, which
represents only the monetary value of market disturbances.
[[Page 53017]]
1. Market Exit Estimates
The hazardous waste combustion industry operates in a dynamic
market, with a number of systems/facilities projected to exit the
hazardous waste burning market under baseline conditions (see Section
V. B of this Part). As a result, this analysis presents market exit
estimates expected to result under the baseline, as well as from
today's rule. This approach is developed in an effort to present a more
accurate estimate of ``real-world'' incremental impacts resulting from
the final standards. Market exit estimates are derived from a breakeven
analysis designed to determine system and facility viability. This
analysis is subject to several assumptions, including: engineering cost
data on the baseline costs of waste burning, cost estimates for
pollution control devices, prices for combustion services, and
assumptions about the waste quantities burned at these facilities. It
is important to note that, for most sectors, exiting the hazardous
waste combustion market is not equivalent to closing a plant. (Actual
plant closure would only be expected in the case of an exit from the
hazardous waste combustion market of a commercial incinerator closing
all its systems.)
A relatively small percentage of facilities (including no
lightweight aggregate kilns) are projected to stop burning hazardous
waste as a result of the incremental requirements associated with
today's rule. Those facilities that do exit were found to be marginally
profitable in the baseline, burning low quantities of hazardous waste.
The economic model post-consolidation results indicate that, in
response to today's rule, the following number of combustion facilities
are expected to cease burning hazardous waste in the short term: Cement
kilns, zero out of 18 facilities; lightweight aggregate kilns, zero out
of five facilities; commercial incinerators, zero out of 20 facilities;
and private on-site incinerators, 16 out of 111 facilities.
The number of anticipated market exits increases in the long term
due to the necessity of recovering the capital costs of combustion.
However, because this also holds true in the baseline, an increased
number of projected long-term baseline market exits may, in some cases,
actually decrease the number of incremental long-term exits. There
remain zero incremental market exits for LWAKs and commercial
incinerators over the long-term. Incremental market exits for cement
kilns, however, increase from zero in the short-term to up to two over
the long-term. Incremental market exits for private on-site
incinerators decline from 16 in the short-term to 13 over the long-
term. This is due to a 62 percent increase in baseline market exits
from the short-term to the long-term.
2. Quantity of Waste Reallocated
Combustion systems that can no longer cover costs (i.e., those
below the dynamic breakeven quantity) are projected to stop burning
hazardous waste. Hazardous wastes from these systems will likely be
reallocated to other viable combustion systems at the same facility if
there is sufficient capacity, alternative combustion facilities that
continue burning, or waste management alternatives (e.g., solvent
reclamation). Because combustion is likely to remain the lowest cost
option, we expect most reallocated wastes will continue to be managed
at combustion facilities.
The economic model indicates that, in response to today's rule,
between 14,000 to 42,000 tons of currently burned hazardous waste could
be reallocated to other facilities or waste management alternatives.
This estimate represents between 0.4 and 1.3 percent of the total
quantity of combusted hazardous wastes and is incremental to projected
long-term baseline reallocations of approximately 100,000 tons.
Currently, there is more than adequate capacity within the remaining
sources of the combustion market to accommodate this reallocated waste,
even at the high-end estimate.
3. Employment Impacts
Today's rule is likely to cause employment shifts across all of the
hazardous waste combustion sectors. These shifts will occur as specific
combustion facilities find it no longer economically feasible to keep
all of their systems running, or to stay in the hazardous waste market
at all. When this occurs, workers at these locations may lose their
jobs. At the same time, the rule may result in employment gains, as new
purchases of pollution control equipment stimulate additional hiring in
the pollution control manufacturing sector and as additional staff are
required at combustion facilities for various compliance activities.
a. Employment Impacts--Losses. Primary employment losses in the
combustion industry are likely to occur when combustion systems
consolidate the waste they are burning into fewer systems or when a
facility exits the hazardous waste combustion market altogether.
Operation and maintenance labor hours are expected to be reduced for
each system that stops burning hazardous waste. For each facility that
completely exits the market, employment losses will likely also include
supervisory and administrative labor.
Total incremental employment dislocations potentially resulting
from the final standards range from approximately 100 to 230 full-time-
equivalent (FTE) jobs under the floor and the recommended options.
Under the beyond-the-floor (ACI) option the high-end estimate of
employment dislocations increases by almost 9 percent to approximately
250 FTEs. Among the different sectors, on-site incinerators are
responsible for most of the total estimated number of job losses. Their
significant share of the losses is a function of both the large number
of on-site incinerators in the universe as well as the relatively high
number of expected exits within this sector. Cement kilns are
responsible for the second largest number of expected employment losses
due to the number of systems that consolidate waste-burning at these
facilities.
b. Employment Impacts--Gains. In addition to employment losses,
today's rule will also lead to job gains as firms invest to comply with
the various requirements of the rule and add additional operation and
maintenance personnel for the new pollution equipment and other
compliance activities, such as new reporting and record keeping
requirements.
The total annual employment gains (without particulate matter
continuous emission monitors) associated with the floor and recommended
final standards are approximately 300 FTEs. The beyond-the-floor (ACI)
option may increase the high-end employment gain estimate to as much as
620 FTEs. About one-third to one-half of all estimated job gains are
projected to occur in the pollution control equipment industry. The
remaining job gains will occur at the combustion facilities as
additional personnel are hired for operation and maintenance and
permitting requirements.
While it may appear that this analysis suggests overall net job
creation under particular options and within particular combustion
sectors, such a conclusion would be inappropriate. Because the gains
and losses occur in different sectors of the economy, they should not
be added together. Doing so would mask important distributional effects
of the rule. In addition, the employment gain estimates reflect within
sector impacts only and therefore do not account for job displacement
across sectors as
[[Page 53018]]
investment funds are diverted from other areas of the larger economy.
4. Combustion Price Increases
All combustion facilities that remain in operation will experience
increased operational costs under today's rule. To protect their
profits, each facility will have an incentive to pass these increased
costs on to their customers (generators and blenders) in the form of
higher combustion prices. Generators and blenders are expected to pay
these higher prices unless they have less expensive waste management
alternatives.
Under the theory of market price adjustments, as applied in the
economic model, waste would be sent to the least expensive alternatives
first, all else being equal. At the same time, prices would rise to the
point at which all demand for waste management is met. In theory, the
last tons would be managed by substituting non-combustion or waste
minimization alternatives. The most efficient waste management
substitute for these wastes would cap price increases, resulting in a
new market price. Combustion facilities, in turn, would each set their
prices at this market price in order to maximize profits. Less
efficient waste management scenarios may earn just enough to stay in
business over the short term, but would not recover capital costs.
Combustion systems operating above the market price would lower their
prices or exit the market. In reality, the hazardous waste combustion
marketplace is very complex, and the determination of an adjusted
market price would be an ongoing process affected by numerous factors,
including price differentials among regions, waste stream types, and
generators.
Available economic data on the cost of waste management
alternatives for combusted hazardous waste, including source reduction
and other waste minimization options, are not precise enough to allow
for an accurate estimate of the maximum price increase that combustors
may pass through to generators and fuel blenders. However, available
data do indicate that the demand for hazardous waste combustion is
relatively inelastic and that combustion facilities are likely to pass
through approximately 75 percent of compliance costs in the least-cost
sector. High-cost sectors, however, may pass through less than the 75
percent estimate. We also analyzed a 25 percent price pass through
scenario. Under the recommended final standards, the weighted average
combustion price per ton is projected to increase anywhere from about
0.5 to 11 percent, depending upon sector and scenario. Prices were
found to increase by as much as 25 percent under the beyond-the-floor
(ACI) option.
5. Industry Profits
Hazardous waste-burning profits for all combustion sectors, on
average, are expected to decline post-rule. This decline, however, will
not be consistent across sectors. Hazardous waste-burning profits for
cement kilns are projected to decrease by no more than 10 percent,
while profits for commercial incinerators would decrease by no more
than 2 percent. These profit margin estimates are based on a simple
calculation that subtracts projected operating costs from revenues.
These estimates provide relative measures of profit changes and should
not be used to predict absolute profit margins in these industries.
Compliance costs associated with meeting today's rule are estimated
to represent less than 2 percent of the pollution control expenditures
in industries that contain facilities with on-site incinerators. For
cement kilns, however, compliance costs are expected to increase total
pollution control expenditures by no more than 60 percent at waste-
burning facilities.
To comply with today's rule, many facilities will need to purchase
additional pollution control equipment. From the perspective of the
pollution control industry, these expenditures will translate into
additional revenues and profits. Total profits for the air pollution
control industry are likely to increase as a result of today's rule.
6. National-Level Joint Economic Impacts
Analyzing national-level economic impacts in a market context
provides an opportunity to assess the distributional effects on cement
producers, lightweight aggregate kilns, and commercial incinerators. As
a supplement to today's analysis, we used the model developed for the
Portland Cement MACT rulemaking to estimate national-level economic
impacts of today's Hazardous Waste Combustion (HWC) MACT rule in an
interactive market context. This analysis was conducted to estimate
joint impacts of today's rule in conjunction with the Portland Cement
MACT rule and the Cement Kiln Dust rule. The Portland Cement MACT model
incorporates compliance costs for each affected cement kiln,
lightweight aggregate kiln, and commercial incinerator and then
projects national level impacts associated with these facilities and
for the general Portland cement market. On-site incinerators were not
included in this analysis because they do not generally compete in the
commercial hazardous waste combustion market. Results from this
analysis are separated into three categories: Market-, industry-, and
social-level impacts associated with imposition of the recommended
final standards and the two HWC MACT options (floor and beyond-the-
floor (ACI)).
Joint national-level economic impact results combining the HWC MACT
options with the Portland Cement MACT and Cement Kiln Dust Rule are
summarized in this section. Market, industry, and social cost impacts
are discussed. This analysis assumes simultaneous implementation of all
three rules.
Market-level impacts for this joint scenario, assuming the floor
option, result in increased costs of cement production and burning
hazardous waste at affected cement kilns. The national market price of
Portland cement is projected to increase by about 2.0 percent, while
domestic production would decline by about 4.0 percent. Market impacts
for the joint scenario with the recommended final standards and the
beyond-the-floor (ACI) option were found to be generally equivalent to
results under the floor option. The extent to which domestic cement
producers face competition from foreign cement imports will limit the
degree of domestic price increases. Furthermore, the U.S. cement market
is regionally specific. While nationwide average market price and
production impacts are estimated to be relatively minor, producers in
selected regions may experience significant revenue and production
impacts, either positive or negative.
Under the joint scenario with the floor option, the market prices
for both liquid and solid hazardous waste incineration are projected to
increase by about 8.6 percent and 1.4 percent, respectively. The price
change for liquids is higher than that observed for the floor only,
while the price change for solids is virtually the same. For cement
kilns, the increased costs associated with all three regulations,
combined with their reductions in cement production, is projected to
cause their supply of hazardous waste incineration services to fall by
around 11.0 percent for both liquids and solids. In response to the
regulatory costs, lightweight aggregate kilns also reduce their supply
of liquid hazardous waste incineration by around 9.0 percent. For
commercial incinerators, the supply of hazardous waste incineration
increases by nearly 6.0 percent for liquids and close to 3.0
[[Page 53019]]
percent for solids. The market impacts for the joint scenario, using
the recommended final standards and the beyond-the-floor (ACI)
alternative, were found to be similar to those for the floor option.
One exception is the market price for liquids, which increases by a
greater percentage under the joint scenario with the beyond-the-floor
(ACI) alternative. This results in a greater reduction in liquid
hazardous waste burned at cement kilns and lesser decreases in liquids
incinerated at commercial incinerators.
Industry-level impacts under the joint impacts scenario with the
floor option indicate that Portland cement plants may see total gross
revenues decline by nearly 3.0 percent from their current baseline.
This decline in total revenue results from foregone revenues associated
with producing less Portland cement and lost revenues from burning
hazardous waste. The total net costs for these cement plants are also
projected to decrease, reflecting the increase in costs associated with
burning hazardous waste, plus the increase in cement kiln dust
management costs, and the decrease in costs associated with producing
less cement. The net result, indicates a decline in aggregate
nationwide earnings before interest and taxes (EBIT) of about 5.5
percent from the current baseline. Lightweight aggregate kilns are also
projected to incur a decline in hazardous waste-related EBIT of about
5.5 percent. Alternatively, as a group, the commercial incinerators are
expected to experience a net gain of around 11.0 percent in annual
earnings under this joint scenario with the floor option. These joint
industry-level impacts on EBIT indicate a similar pattern across each
regulatory scenario, except for lightweight aggregate kilns under the
beyond-the-floor (ACI) option, where EBIT declines by nearly 14.0
percent. Industry-level impacts under the joint impact analysis also
includes estimates of plant or system closures. The joint analysis
under each hazardous waste combustion scenario indicates that three
cement plants and 14 to 15 kilns may cease production. Furthermore,
five cement kilns are projected to stop burning hazardous waste. The
analysis also indicates that one lightweight aggregate kiln may
discontinue burning hazardous waste and one to two commercial
incinerators may close operations and stop burning hazardous waste with
the joint implementation of all three rules. These market exit
estimates include projected baseline closures.
Social-level impacts, or social costs, under the joint scenarios
indicate that, for both Portland cement and hazardous waste
incineration services, consumers are worse off due to the increase in
prices and reductions in consumption. For producers of Portland cement
and incineration services, cement kilns and lightweight aggregate kilns
are worse off (on a nationwide basis) due to the decline in market
share, while commercial incinerators are better off due to the increase
in prices and market share.
Refer to the final Assessment document and appendices for a
complete discussion of joint impacts.
G. Analytical Methodology and Findings--Benefits Assessment
This section discusses the benefits assessment for today's rule.
Results from our multi-pathway human health and ecological risk
assessment are used to evaluate incremental benefits to society of
emission reductions at hazardous waste combustion
facilities.351 Total monetized benefits are estimated at
$19.2 million. This section also summarizes how today's rule may lead
to changes in the types and quantities of wastes generated and managed
at combustion facilities through increased waste minimization.
---------------------------------------------------------------------------
\351\ The RIA for the proposal included results from a screening
analysis designed to assess the potential magnitude of property
value benefits caused by the MACT standards. This analysis is not
included in the Economic Assessment for the Final Rule due to
limitations of the benefits transfer approach and because property
value benefits likely overlap with human health and ecological
benefits. Including property value benefits would result in double-
counting.
---------------------------------------------------------------------------
1. Human Health and Ecological Benefits
a. Risk Assessment Overview. The basis for the benefits assessment
is our multi-pathway risk assessment model. This model estimates
baseline risks from hazardous waste combustion emissions, as well as
expected risks after today's rule is implemented. The model examines
both inhalation and ingestion pathways to estimate human health risks.
A less detailed screening-level analysis is used to identify the
potential for ecological risks. The risk assessment is carried out for
the regulatory baseline (no regulation), the final recommended
standards, and the two MACT options (floor and beyond-the-floor (ACI)).
The assessment uses a case study approach in which 76 hazardous waste
combustion facilities and their site-specific land uses and
environmental settings are characterized. The randomly selected
facilities in the study include 43 on-site incinerators, 13 commercial
incinerators, 15 cement kilns, and five lightweight aggregate kilns.
The pollutants analyzed in the risk assessment are dioxins and
furans, selected metals, particulate matter, chlorine, and hydrogen
chloride. The metals modeled in the analysis include antimony, arsenic,
barium, beryllium, cadmium, chromium, copper, cobalt, lead, manganese,
mercury, nickel, selenium, silver, and thallium. The fate and transport
of the emissions of these pollutants is modeled to arrive at
concentrations in air, soil, surface water, and sediments. To assess
human health risks, these concentrations can be converted to estimated
doses to the exposed populations using exposure factors such as
inhalation and ingestion rates. These doses are then used to calculate
cancer and noncancer risks, if the appropriate health benchmarks are
available. To assess potential ecological risks, soil, surface water
and sediment concentrations are compared with eco-toxicological
criteria representing protective screening values for ecological risks.
Because these criteria are based on de minimis ecological effects and
thus represent conservative values, an exceedance of the eco-
toxicological criteria does not necessarily indicate ecological
damages. It simply suggests that potential damages cannot be ruled out.
To characterize the cancer and noncancer risks to the populations
listed above, the risk assessment breaks down the area surrounding each
modeled combustion facility into 16 polar grid sectors. For each polar
grid sector, risk estimates can be developed for different age groups
and receptor populations (e.g., 0 to 5 year old children of subsistence
fishers). This approach is used because geographic and demographic
differences across polar grid sectors leads to sectoral variation in
individual risks. Thus, individual risk results are aggregated across
sectors to generate the distribution of risk to individuals in the
affected area. An additional Monte Carlo analysis was conducted to
incorporate variability in other exposure factors such as inhalation
and ingestion rates for three scenarios that were thought to comprise
the majority of the risk to the study area population. These scenarios
address cancer risk from dioxin exposure to beef and dairy farms and
noncancer risk from methyl mercury exposure to recreational anglers.
b. Human Health Benefits--Methodology. Human health benefits are
assessed by identifying those pollutants for which emission reductions
are expected to result in improvements to human health or the
[[Page 53020]]
environment. The relevant results from the risk assessment for the
pollutants of concern are then examined, focusing on population risk
results based on central tendency exposure parameters. The risk
assessment data are expressed as indicators of potential benefits, such
as reduced cancer incidence or reduced potential for developing
particular illnesses or abnormalities. Where possible, monetary values
are assigned to these benefits using a benefits transfer approach.
To assign monetary values to cancer risk reduction estimates, we
apply the value of a statistical life to the risk reduction expected to
result from the MACT standards. The value of a statistical life is
based on an individual's willingness to pay to reduce a risk of
premature death or their willingness to accept increases in mortality
risk. Because there are many different estimates of value of a
statistical life in the economic literature, we estimate the reduced
mortality benefits using a range of value of a statistical life
estimates from 26 policy-relevant value-of-life studies. The estimated
value of a statistical life figures from these studies range from $0.7
million to $15.9 million (adjusted to 1996 dollars), with a mean value
of $5.6 million. The expected number of annual premature statistical
deaths avoided are multiplied by the value of a statistical life
estimate to determine the estimated monetary value of the mortality
risk reductions.
A variety of approaches are used to evaluate the benefits
associated with noncancer risk reductions. For particulate matter, both
morbidity and mortality benefits are estimated. Particulate matter is
the only non-carcinogen in the risk assessment for which there is
sufficient dose-response information to estimate numbers of cases of
disease and deaths from exposures. For lead and mercury, upper bound
estimates of the population at risk are used. This is because
information is only available on the potential of an adverse effect,
with no estimates available on the likelihood of these effects.
We assign monetary values to noncancer benefits using a direct cost
approach which focuses on the expenditures averted, and the opportunity
cost of time spent in the hospital, by decreasing the occurrence of an
illness or other health effect. While the willingness to pay approach
used for valuing the cancer risk reductions is conceptually superior to
the direct cost approach, measurement difficulties, such as estimating
the severity of various illnesses, precludes us from using this
approach here. Direct cost measures are expected to understate true
benefits because they do not include cost of pain, suffering, and time
lost. On the other hand, because we use upper bound estimates of the
population at risk, we cannot conclude that the results are biased in
one direction or the other.
c. Human Health Benefits--Results. Human health benefits are
expected from both cancer and noncancer risk reductions. Less than one
cancer case per year is expected to be avoided due to reduced emissions
from combustion facilities. The majority of the cancer risk reductions
are linked to consumption of dioxin-contaminated agricultural products
exported beyond the boundaries of the study area. Less than one-third
of the cancer risk reductions occur in local populations living near
combustion facilities. Cancer risks for local populations are
attributed primarily to reductions in arsenic and chromium emissions.
These pollutants account for almost 85 percent of total local cancer
incidences in the baseline. By applying value of a statistical life
estimates to these cases, the total annual cancer risk reductions
(benefits) in going from the baseline to the final standards, are
valued at between $0.13 and $9.9 million, with a best estimate of
approximately $2.02 million.
Across all receptor populations, individual cancer risks are
greatest for subsistence farmers. Dioxin is the primary pollutant that
drives the cancer risk for this sensitive receptor population. A lack
of population data prevented us from quantifying benefits for this sub-
population. It is possible, however, to characterize the reduction in
risk from baseline to implementation of today's rule. With the
exception of one particular scenario, the cancer risk for all
subsistence farmers is reduced to below levels of concern after
implementation of today's rule. Today's rule is also expected to result
in lower cancer risks for children of subsistence farmers.
Most of the noncancer human health benefits from today's rule come
from reductions in particulate matter. Some additional noncancer
benefits come from reduced blood lead levels in children living near
combustion facilities. Total annual noncancer benefits from
quantifiable sources are valued at between $9.85 and $73.8 million,
with a best estimate of about $17.2 million. Uncertainties implicit in
the quantitative mercury analysis continue to be sufficiently great so
as to limit its ultimate use in the monetization of noncancer benefits.
Please review the Addendum and chapter six of the Assessment document
for a complete discussion of human health benefits resulting from
today's rule.
d. Ecological Benefits--Methodology. Ecological benefits are based
on a screening analysis for ecological risks that compares soil,
surface water, and sediment concentrations with eco-toxicological
criteria based on de minimis thresholds for ecological effects. Because
these criteria represent conservative values, an exceedance of the eco-
toxicological criteria only indicates the potential for adverse
ecological effects and does not necessarily indicate ecological
damages. For this reason, benefits of avoiding adverse ecological
impacts are discussed only in qualitative terms.
The basic approach for determining whether ecosystems or biota are
potentially at risk consists of five steps: (1) Identify susceptible
ecological receptors that represent relatively common species and
communities of wildlife, (2) develop eco-toxicological criteria for
receptors that represent acceptable pollutant concentrations, (3)
estimate baseline and post-rule pollutant concentrations in sediments,
soils, and surface waters of the study areas, (4) for each land area or
water body modeled, compare the modeled media concentrations to
ecologically protective levels to estimate eco-toxicological hazard
quotients, and (5) total the land and water areas containing hazard
quotients exceeding one and compare this number for the baseline and
post-rule scenario. The reduction in the land and water area
potentially at risk indicates a potential for avoiding adverse
ecological impacts. Monetary values are not assigned to these potential
benefits.
e. Ecological Benefits--Results. Ecological benefits are
attributable primarily to reductions in dioxin and mercury for
terrestrial ecosystems. For these ecosystems, hazard quotients are
reduced to acceptable levels for approximately 115 to 150 square
kilometers of land located within 20 kilometers of all combustion
facilities. Ecological benefits associated with freshwater aquatic
ecosystems are attributable to reductions in lead, with hazard
quotients reduced to acceptable levels for approximately 35 to 40
square kilometers of these surface waters. These reductions of
ecological risk criteria below levels of concern only indicates a
potential for ecological improvement.
2. Waste Minimization Benefits
While many facilities may implement end-of-pipe controls such as
fabric
[[Page 53021]]
filters and high-energy scrubbers to achieve MACT control, emission
reductions may also be accomplished by reducing the volume or toxicity
of wastes currently combusted. In addition, generators may also
consider waste management alternatives such as solvent recycling. For
purposes of this analysis, these types of responses will be referred to
as ``waste minimization.'' This section summarizes the potential waste
minimization benefits resulting from implementation of today's rule.
As today's rule is implemented, the costs of burning hazardous
waste will increase, resulting in market incentives for greater waste
minimization. To predict the quantity of waste that could be
reallocated from combustion to waste minimization due to economic
considerations, we conducted a comprehensive waste minimization
analysis that considered in-process recycling, out-of-process
recycling, and source reduction. The objective of the analysis was to
predict the quantity of hazardous wastes that may be reallocated to
these waste minimization alternatives under different combustion price
increase scenarios.
Overall, the analysis shows that a variety of waste minimization
alternatives are available for managing those hazardous waste streams
that are currently combusted. The quantity projected to be reallocated
from combustion to waste minimization alternatives, however, depends
upon the expected price increase for combustion services. At potential
price increases ranging from $10 to $20 per ton, as much as 240,000
tons of hazardous waste may be reallocated from combustion to waste
minimization alternatives. This represents approximately 7 percent of
the total quantity of hazardous waste currently combusted.
VI. What Considerations Were Given to Issues Like Equity and Children's
Health?
By applicable statute and executive order, we are required to
complete an analysis of today's rule with regard to equity
considerations and other regulatory concerns. This section assesses the
potential impacts of today's rule as it relates to environmental
justice, children's health issues, and unfunded federal mandates. Small
entity impacts are examined in a separate section.
A. Executive Order 12898, ``Federal Actions To Address Environmental
Justice in Minority Populations and Low-Income Populations'' (February
11, 1994)
This Order is designed to address the environmental and human
health conditions of minority and low-income populations. To comply
with the Executive Order, we have assessed whether today's rule may
have disproportionate effects on minority populations or low-income
populations. We have analyzed demographic data presented in the reports
``Race, Ethnicity, and Poverty Status of the Populations Living Near
Cement Plants in the United States'' (EPA, August 1994) and ``Race,
Ethnicity, and Poverty Status of the Populations Living Near Hazardous
Waste Incinerators in the United States'' (EPA, October 1994). These
reports examine the number of low-income and minority individuals
living near a relatively large sample of cement kilns and hazardous
waste incinerators and provide county, state, and national population
percentages for various sub-populations. The demographic data in these
reports provide several important findings when examined in conjunction
with the risk reductions projected from today's rule.
We find that combustion facilities, in general, are not located in
areas with disproportionately high minority and low-income populations.
However, there is evidence that hazardous waste burning cement kilns
are somewhat more likely to be located in areas that have relatively
higher low-income populations. Furthermore, there are a small number of
commercial hazardous waste incinerators located in highly urbanized
areas where there is a disproportionately high concentration of
minorities and low-income populations within one and five mile radii.
The reduced emissions at these facilities due to today's rule could
represent meaningful environmental and health improvements for these
populations. Overall, today's rule should not result in any adverse
environmental or health effects on minority or low-income populations.
Any impacts on these populations are likely to be positive due to the
reduction in emissions from combustion facilities near minority and
low-income population groups. The Assessment document available in the
RCRA docket established for today's rule presents the full
Environmental Justice Analysis.
B. Executive Order 13045: Protection of Children From Environmental
Health Risks and Safety Risks (62 FR 19885, April 23, 1997)
Executive Order 13045: ``Protection of Children from Environmental
Health Risks and Safety Risks'' (62 FR 19885, April 23, 1997) applies
to any rule that: (1) Is determined to be ``economically significant''
as defined under E.O. 12866, and (2) concerns an environmental health
or safety risk that EPA has reason to believe may have a
disproportionate effect on children. If the regulatory action meets
both criteria, the Agency must evaluate the environmental health or
safety effects of the planned rule on children, and explain why the
planned regulation is preferable to other potentially effective and
reasonably feasible alternatives considered by the Agency.
Today's final rule is not subject to the Executive Order because it
is not economically significant as defined under point one of the
Order, and because the Agency does not have reason to believe the
environmental health or safety risks addressed by this action present a
disproportionate risk to children.
The topic of environmental threats to children's health is growing
in regulatory importance as scientists, policy makers, and village
members continue to recognize the extent to which children are
particularly vulnerable to environmental hazards. Recent EPA actions
including today's rule, are in the forefront of addressing
environmental threats to the health of children. The risk assessment
conducted in support of today's rule indicates that children are the
beneficiaries of much of the reduction in potential illnesses and other
adverse effects associated with combustion facility emissions. The risk
assessment used a multi-pathway and multi-constituent evaluation in
order to examine potential effects of combined exposures on children.
Setting environmental standards that address combined exposures and
that are protective of the heightened risks faced by children are both
goals named within EPA's ``National Agenda to Protect Children's Health
from Environmental Threats.'' Areas for potential reductions in risks
and related health effects that were identified by the risk assessment
are all targeted as priority issues within EPA's September 1996 report,
Environmental Health Threats to Children.
A few significant physiological characteristics are largely
responsible for children's increased susceptibility to
[[Page 53022]]
environmental hazards. First, children eat proportionately more food,
drink proportionately more fluids, and breathe more air per pound of
body weight than do adults. As a result, children potentially
experience greater levels of exposure to environmental threats than do
adults. Second, because children's bodies are still in the process of
development, their immune systems, neurological systems, and other
immature organs can be more easily and considerably affected by
environmental hazards. The connection between these physical
characteristics and children's susceptibility to environmental threats
are reflected in the higher baseline risk levels for children living
near hazardous waste combustion facilities. The risk assessment
addresses threats to children's health associated with hazardous waste
combustion by evaluating reductions in risk for children as well as for
adults and the population overall. For all exposed sub-populations, the
assessment evaluated risks to four different age groups: 0 to 5 years,
6 to 11 years, 12 to 19 years, and adults over 20 years. Where
possible, the risk assessment has provided both population and
individual risk results for children. Both cancer and noncancer risks
are examined across the age groups of children, focusing on the most
susceptible sub-populations. The combined effects of several
carcinogens, one of the goals named within the Agency's ``National
Agenda to Protect Children's Health from Environmental Threats,'' were
examined.
The key findings from the risk assessment indicate that children do
not face significant cancer risks from hazardous waste combustion
emissions. Only in the case of children of subsistence farmers do
baseline cancer risks exceed 1 x 10-5 for the most highly
exposed children. Implementation of the final standards would reduce
these risks below levels of concern 352.
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\352\ Also, the analysis used the same approach to estimate
cancer risks in both adults and children. However, individuals
exposed to carcinogens in the first few years of life may be at
increased risk of developing cancer. For this reason, we recognize
that significant uncertainties and unknowns exist regarding the
estimation of lifetime cancer risks in children. We also note that
this analysis of cancer risks in children has not been externally
peer reviewed.
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The analysis also found that much of the noncancer risk reductions
resulting from implementation of today's rule may benefit children
specifically. These are projected as a result of lower exposures to
mercury, lead, and particulate matter, three types of pollutants
addressed in the noncancer risk reductions which primarily affect
children. Mercury emission reductions may reduce risks of developmental
abnormalities in potential future offspring of recreational anglers and
subsistence fishermen. In addition, particulate matter reductions may
prevent some asthma attacks affecting children, but these benefits have
not been quantified. Finally, reduced lead exposures for children are
expected from today's rule. This benefit may help prevent cognitive and
nervous system developmental abnormalities for children of the most
highly exposed sub-populations, including subsistence fishermen and
beef and dairy farmers. Analytical and data limitations prevented
reasonable monetization of these findings.
C. Unfunded Mandates Reform Act of 1995 (UMRA) (Pub. L. 104-4)
Executive Order 12875, ``Enhancing the Intergovernmental
Partnership'' (October 26, 1993), calls on federal agencies to provide
a statement supporting the need to issue any regulation containing an
unfunded federal mandate and describing prior consultation with
representatives of affected state, local, and tribal governments.
Signed into law on March 22, 1995, the Unfunded Mandates Reform Act
(UMRA) supersedes Executive Order 12875, reiterating the previously
established directives while also imposing additional requirements for
federal agencies issuing any regulation containing an unfunded mandate.
Today's rule is not subject to the requirements of sections 202,
204 and 205 of UMRA. In general, a rule is subject to the requirements
of these sections if it contains ``Federal mandates'' that may result
in the expenditure by State, local, and tribal governments, in the
aggregate, or by the private sector, of $100 million or more in any one
year. Today's final rule does not result in $100 million or more in
expenditures. The aggregate annualized social costs for today's rule
are projected to range from $50 to $63 million under the final
standards.
For rules that are subject to the requirements of these sections,
key requirements include a written statement with an analysis of
benefits and costs; input from state, local and tribal governments; and
selection of the least burdensome option (if allowed by law) or an
explanation for the option selected. We recognize the potential for
aggregate one-time capital expenditures to exceed $100 million in any
one year should various industry sectors choose not to amortize capital
expenditures. Under this scenario, the Assessment document for today's
rule meets analytical requirements established under UMRA.
Today's rule is not subject to the requirements of section 203 of
UMRA. Section 203 requires agencies to develop a small government
Agency plan before establishing any regulatory requirements that may
significantly or uniquely affect small governments, including tribal
governments. EPA has determined that this rule will not significantly
or uniquely affect small governments. The small entity impacts
analysis, presented in Appendix G of the final Assessment, found that
no hazardous waste combustion units are owned by small governments.
Finally, because we are issuing today's rule under the statutory
authority of the Clean Air Act, the rule should be exempt from all
relevant requirements of the UMRA. In addition, compliance with the
rule is voluntary for nonfederal governmental entities since state and
local agencies choose whether or not to apply to EPA for the permitting
authority necessary to implement today's rule.
VII. Is Today's Rule Cost Effective?
We have developed a cost-effectiveness measure that examines cost
per unit reduction of emissions for each hazardous air pollutant,
pollutant group, or surrogate. Cost-effectiveness measures are useful
for comparing across different air pollution regulations. Moreover, we
have typically used cost-effectiveness measures (defined as ``dollar-
per-unit of pollutant removed'') to assess the decision to go beyond-
the-floor for MACT standards.
Developing cost-effectiveness estimates for individual air
pollutants assists us in making beyond-the-floor decisions for
individual pollutants. The two analytic components of the individual
cost-effectiveness analysis are: (1) Estimates of emission control
expenditures per air pollutant for each regulatory option, and (2)
estimates of emission reductions under each regulatory option.
Individual cost-effectiveness measures for each MACT option are
calculated as follows:
HWC MACT Floor--Costs and emission reductions are
incremental to the baseline,
HWC MACT Final Standards--Costs and emission reductions
are incremental to the MACT Floor, and
Beyond-the-Floor--Activated Carbon Injection (ACI) MACT--
Costs and emission reductions are incremental to the MACT Floor.
Single-level cost-effectiveness results across all HWC MACT options
range
[[Page 53023]]
from seven hundred dollars to $34.3 million per megagram reduced for
all pollutants, individually, except dioxin. Dioxin control ranges from
$25,000 to $903,000 per gram reduced. Dioxin control for incinerators
to meet the floor standard is estimated at $903,000 per gram, with an
additional $368,000 per gram to go from the floor to the final BTF TEQ
standard. The control of SVM emitted from cement kilns is estimated to
cost $67,000 per megagram from the baseline to the floor. Moving from
the floor standard to the final BTF SVM standard for cement kilns is
estimated to cost $502,000 per megagram. These results indicate that
the more highly toxic pollutants such as dioxin are often much more
expensive to control on a per-gram basis.
We did not apply cost-effectiveness alone in establishing beyond-
the-floor levels for selected constituents regulated under the final
HWC MACT standards. Several other measurement factors were incorporated
into the beyond-the-floor decision, including: health benefits
(especially those for children), regulatory precedent, cost-
effectiveness of other MACT standards, and reliability of baseline
data.
The method for calculating cost-effectiveness makes several
simplifying assumptions. The two most important address the metrics
employed for measuring cost-effectiveness and the actual methodology
used to estimate the cost and emission reduction figures. Alternative
measurement criteria for different constituents may lead to perceived
distortions in scope. The cost-effectiveness methodology assumes that
all facilities continue operating and install pollution control
equipment or implement feed reductions to comply with the MACT
standards. Both of these limiting assumptions may lead to overstatement
or understatement of results. Other limitations that will influence
these cost-effectiveness estimates include: (1) The feed control
costing approach, which may lead to the overstatement of expenditures
per pollutant due to the assumption of upper-bound cost estimates, (2)
apportionment of costs, which are currently assigned according to the
percentage reduction required to meet the standard for each pollutant
controlled by the device, and (3) the assumption that units control
emissions to the 70 percent design level.
VIII. How Do the Costs of Today's Rule Compare to the Benefits?
Comparing overall costs and benefits may help provide an assessment
of this rule's overall efficiency and impacts on society. This section
compares the total social costs of today's rule with its total
monetized and nonmonetized benefits. The total annual monetized
benefits of today's rule are estimated at $19.2 million (undiscounted)
for the recommended final standards. These monetized benefits, however,
may represent only a subset of potential avoided health effects, both
cancer and noncancer cases. In comparison, the total annualized social
costs of the rule are projected to range from $50 to $63 million.
Social costs also include government administrative costs.
Across regulatory options, costs exceed monetized benefits more
than two-fold. However, today's rule is expected to provide benefits
that cannot be readily expressed in monetary terms. These benefits
include health benefits to sensitive sub-populations such as
subsistence anglers and improvements to terrestrial and aquatic
ecological systems. When these benefits are taken into account, along
with equity-enhancing effects such as environmental justice and impacts
on children's health, the benefit-cost comparison becomes more complex
but also more favorable. Consequently, the final regulatory decision
becomes a policy judgment which takes into account efficiency as well
as equity concerns and the positive direction of real, but
unquantifiable, benefits.
IX. What Consideration Was Given to Small Businesses?
A. Regulatory Flexibility Act (RFA) as amended by the Small Business
Regulatory Enforcement Fairness Act of 1996 (SBREFA), 5 USC 601 et seq.
This Act generally requires an agency to prepare a regulatory
flexibility analysis of any rule subject to notice and comment
rulemaking requirements under the Administrative Procedure Act or any
other statute unless the agency certifies that the rule will not have a
significant economic impact on a substantial number of small entities.
Small entities include small businesses, small not-for-profit
enterprises, and small governmental jurisdictions.
We have determined that hazardous waste combustion facilities are
not owned by small entities (local governments, tribes, etc.) other
than businesses. Therefore, only businesses were analyzed. For the
purposes of the impact analyses, small entity is defined either by the
number of employees or by the dollar amount of sales. The level at
which a business is considered small is determined for each Standard
Industrial Classification (SIC) code by the Small Business
Administration.353
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\353\ SIC codes are used rather than the new NAICS codes because
waste generator, blender, and combustor data were only available
according to SIC code. However, a general conversion table
containing NAICS codes for each reported SIC code is presented in
the Assessment document.
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Affected individual waste combustors (incinerators, cement kilns,
and lightweight aggregate kilns) will bear the impacts of today's rule.
These units will incur direct economic impacts as a result of today's
rule. While not required under the Act and guidelines, we have also
examined potential secondary impacts on small business units
potentially affected by today's rule, such as hazardous waste
generators and fuel blenders. Although hazardous waste combustors are
the only group that would bear direct economic impacts from today's
rule, this ``secondary impacts'' analysis was conducted because we
assume that some portion of the burden would be passed on to customers
of combustion facilities through price increases. This section
describes the small entity analysis we conducted in support of today's
rule.
B. Analytical Methodology
For combustors and blenders, we conducted facility-by-facility
analyses of small businesses. We examined company data on employment
and sales and then compared these data to statutory small business
thresholds based on employment or annual sales, as defined for its
industry by the Small Business Administration in 13 CFR part 121.
Combustion or blender units where the facility or parent company data
fell below the small business thresholds were classified as small
businesses. The analysis was more complex for generators, however,
because the rule may indirectly affect more than 11,000 generators.
Given the large number of generators who would be affected by today's
rule, it was necessary to conduct an initial, broad screening analysis
to identify small business generators that might face significant
secondary impacts. This screening analysis involved assigning each
facility to an industry group, identifying industry groups that are
dominated by small businesses, and then assuming that all generators in
those small business dominated industries are small. Further analyses
were then conducted on these groups or specific facilities.
We next compiled compliance cost data in an effort to establish a
threshold for measuring ``significant economic impact.'' This threshold
was set where compliance costs exceed one percent of
[[Page 53024]]
facility gross sales. If costs do not exceed one percent of sales, then
the regulation is unlikely to have a significant economic impact on
small businesses within the category examined. Finally, we examined
whether the significant economic impact (if any) would be borne by a
``substantial number'' of small businesses. If the regulation results
in required compliance costs exceeding one percent of gross sales for
more than 100 small businesses or 20 percent of all small businesses
within the industry category examined, then the ``substantial number''
threshold is exceeded.
The cost of compliance with the new standards will determine the
severity of impacts on small businesses. The costs to combustors used
in this analysis coincide with the 70 percent engineering standard
analyzed in the full economic assessment. The price increases
experienced by generators and blenders were calculated on a per ton
basis of waste shipped using 25 and 75 percent price pass-through
scenarios. The price impacts were assumed to be uniform across facility
types, with both generators and blenders experiencing the price pass-
through effect. In practice, this pass through would likely be split
between the two, depending on market factors. Note that the impacts
from these price increases are indirect effects, as only hazardous
waste combustors bear direct economic impact of today's rule.
C. Results--Direct Impacts
Only six facilities, out of the total universe of 172 hazardous
waste combustion facilities, met the definition of small businesses. Of
these six, two were found to experience annual compliance costs
exceeding one percent of sales. Both of these facilities are owned by a
common parent that qualifies as a small business. Therefore, this final
rule affects a very limited number of small business combustors and has
effects of greater than one percent on only two of these facilities
(one business).
While the significant economic impact threshold was exceeded for
two facilities (one corporation), these impacts do not extend to a
substantial number of small entities. With just two facilities
exceeding the one percent threshold, neither a substantial number of
facilities nor a substantial fraction of an affected industry would
face these impacts. After considering the economic impacts of today's
final rule on small entities, I certify that this action will not have
a significant economic impact on a substantial number of small
entities.
Although this final rule will not have a significant economic
impact on a substantial number of directly impacted small entities, EPA
nonetheless has assessed the potential of this rule to adversely impact
small entities subject to the rule.
D. Results--Indirect Impacts
Direct impacts of the rule extend only to combustors of hazardous
waste. To supplement our analysis, indirect impacts on generators and
blenders were also examined. We understand that some portion of the
combustor's compliance costs would most likely be passed on to
generators and blenders, and we have made an effort to analyze these
impacts in the spirit of the legislation.
We found that indirect economic effects on generators would not
impose a significant impact on a substantial number of small
generators. Under both price pass-through scenarios (25 and 75
percent), some generators exceeded the one percent cost as percentage
of sales threshold for ``significant impacts.'' In no case, however,
was the ``substantial number'' threshold exceeded. Under the 25 percent
pass-through scenario, 18 generators had a cost as percentage of sales
greater than one percent, but that accounts for only 0.85 percent of
all small business generators. While the impact threshold was exceeded
by 58 generators in the 75 percent pass through scenario, this is still
less than the 100 entity threshold established for a substantial
number. You should note that the sales thresholds were selected
conservatively as the average sales for the smallest establishments in
the SIC code.
Like generators, blenders do not incur direct costs as a result of
the rule. However, they may bear a portion of its impact indirectly as
costs are passed through from combustors. A total of 21 small business
blenders were identified. Depending on the pass-through assumption,
between six and 14 blenders exceed the significant impact threshold.
Impacts for some of these facilities were found to represent a
significant share of their annual gross sales.
Under the 25 percent price pass-through scenario, the number of
blenders exceeding the cost as percentage of sales threshold do not
represent a substantial number of facilities, either in absolute number
or as a percentage of total blenders. Under the 75 percent scenario,
however, the 14 establishments with cost as percentage of sales greater
than one percent represent just over 20 percent of the 67 blenders
identified for this analysis. In a few cases, the cost as percentage of
sales could exceed 10 percent.
E. Key Assumptions and Limitations
This analysis was based on several simplifying assumptions. Four
key assumptions may have the most significant impact on findings.
First, not all small generators may be captured in our analysis of
small business dominated industries. This exclusion may be offset by
the fact that some generators who are not small may be incorporated in
the small business dominated industries. Second, to calculate the
benchmark sales for generators, we used average sales by four-digit SIC
code for firms with fewer than 20 employees. This may understate
economic impacts for the smallest firms in the industry while
overstating impacts for larger firms. Third, compliance costs were
assumed to be passed through almost completely to the shipper of the
waste. This may overstate the impact on generators and blenders.
Finally, we assumed that all waste currently managed by combustion
continues to be disposed of in this manner. Impacts on combustors,
generators, and blenders may be overstated if waste minimization or
other lower cost alternatives are available.
Results from this report should also be evaluated within the
context of some key analytical limitations. For example, in recent
years there has been significant volatility in market behavior and
pricing practices in the hazardous waste combustion industry.
Furthermore, combustion prices have experienced a general downward tend
since 1985 as a result of overcapacity in the market and slow growth in
the generation of hazardous waste. Accounting for this price trend, the
increase expected under today's rule may affect generators and blenders
less significantly than anticipated. Finally, many hazardous waste
generators may be more concerned about other aspects of waste
management than with prices.
X. Were Derived Air Quality and Non-Air Impacts Considered?
The final Combustion MACT standards are projected to result in the
reallocation and diversion of relatively small amounts of hazardous
waste resulting in an unspecified increase in the level of fossil fuel
substitution. This substitution with nonhazardous waste fuel sources
may result in marginal increases in the annual number of mining and
transport injuries, in addition to potential increased emissions of
criteria pollutants (SOx, NOx, and
CO2). We recognize these
[[Page 53025]]
concerns but feel any potential non-air impacts are largely addressed
through alternative regulatory or market scenarios. First, some of the
hazardous waste reallocated from current combustors will likely be sent
to other waste-burning facilities, thereby off-setting primary or
supplementary fossil fuel usage. Even if fossil fuel burning does
increase to some degree, these SO2 and NOx
emissions are expected to be regulated under existing standards, e.g.,
criteria pollutant emissions are currently addressed by the Clean Air
Act. Finally, we find that even if fossil fuel use is increased, the
risks to miners (primarily coal miners) are voluntary risks. Miners are
compensated for these increased risks through wage premiums established
in response to market dynamics and recurrent negotiations between union
and corporate representatives.
While the primary environmental impact of the MACT standards are
improvements in air quality resulting from emissions reductions at
combustion facilities, other non-air environmental impacts also result
from the rule. Namely, use of some air pollution control equipment and
shifts in waste burning result in increased water, solid waste, and
energy impacts. We did not assess the monetary costs of these impacts
because we expect the incremental costs will be small relative to the
total compliance costs of the rule. You are requested to review the
Addendum prepared in support of today's final rule for an expanded
discussion of these impacts.
XI. The Congressional Review Act (5 U.S.C. 801 et seq., as Added by the
Small Business Regulatory Enforcement Fairness Act of 1996)
Is Today's Rule Subject to Congressional Review?
The Congressional Review Act, 5 U.S.C. 801 et seq., as added by the
Small Business Regulatory Enforcement Fairness Act of 1996, generally
provides that before a rule may take effect, the agency promulgating
the rule must submit a rule report, which includes a copy of the rule,
to each House of the Congress and to the Comptroller General of the
United States. EPA will submit a report containing this rule and other
required information to the U.S. Senate, the U.S. House of
Representatives, and the Comptroller General of the United States prior
to publication of the rule in the Federal Register. A Major rule cannot
take effect until 60 days after it is published in the Federal
Register. This action is not a ``major rule'' as defined by 5 U.S.C.
804(2). This rule will be effective September 30, 1999.
XII. Paperwork Reduction Act (PRA), 5 U.S.C. 3501-3520
How Is the Paperwork Reduction Act Considered in Today's Rule?
The Office of Management and Budget (OMB) has approved the
information collection requirements (ICR) contained in this rule under
the provisions of the Paperwork Reduction Act, 44 U.S.C. 3501 et seq.
and has assigned OMB control numbers 2050-0073 (``New and Amended RCRA
Reporting and Recordkeeping Requirements for Boilers and Industrial
Furnaces Burning Hazardous Waste'') for the RCRA provisions and 2060-
0349 (``New and Amended Reporting and Recordkeeping Requirements for
National Emissions Standards for Hazardous Air Pollutants from
Hazardous Waste Combustors'') for the CAA provisions.
EPA is required under section 112(d) of the Clean Air Act to
regulate emissions of HAPs listed in section 112(b). The requested
information is needed as part of the overall compliance and enforcement
program. The ICR requires that affected sources retain records of
parameter and emissions monitoring data at facilities for a period of
five years, which is consistent with the General Provisions to 40 CFR
part 63 and the permit requirements under 40 CFR part 70. All sources
subject to this rule will be required to obtain operating permits
either through the State-approved permitting program or, if one does
not exist, in accordance with the provisions of 40 CFR part 71, when
promulgated. Section 3007(b) of RCRA and 40 CFR part 2, subpart B,
which defines EPA's general policy on the public disclosure of
information, contain provisions for confidentiality.
The public reporting burden for this collection of information for
the CAA provisions under OMB control number 2060-0349 is estimated to
average 297 hours per respondent per year for an estimated 229
respondents. The annual public reporting and record keeping burden for
collection of information is estimated to be 67,977 hours and a cost of
approximately $1.6 million. The total annualized capital costs and
total annualized operation and maintenance costs associated with these
requirements are $15,000 and nearly $1.6 million, respectively.
The estimates for RCRA provisions under OMB control number 2050-
0073 include an annual public reporting and record keeping burden
reduction for collection of information of 131,228 hours and a cost
burden reduction of $4.9 million. The reductions in total annualized
capital costs and total annualized operation and maintenance costs
associated with these requirements are $2.1 million and $2.8 million,
respectively. The negative cost represents the reduced burden on 25
facilities getting out of the hazardous waste combustor universe due to
the comparable fuels exemption. A further reduction in this RCRA
information collection requirement burden will occur after three years
when the combustors will start reporting under the CAA information
collection requirements.
Burden means the total time, effort, or financial resources
expended by persons to generate, maintain, retain, or disclose or
provide information to or for a Federal agency. This includes the time
needed to review instructions; develop, acquire, install, and utilize
technology and systems for the purposes of collecting, validating, and
verifying information, processing and maintaining information, and
disclosing and providing information; adjust the existing ways to
comply with any previously applicable instructions and requirements;
train personnel to be able to respond to a collection of information;
search data sources; complete and review the collection of information;
and transmit or otherwise disclose the information.
An Agency may not conduct or sponsor, and a person is not required
to respond to a collection of information unless it displays a
currently valid OMB control number. The OMB control numbers for EPA's
regulations are listed in 40 CFR part 9 and 48 CFR Chapter 15. EPA is
amending the table in 40 CFR part 9 of currently approved ICR control
numbers issued by OMB for various regulations to list the information
requirements contained in this final rule.
XIII. National Technology Transfer and Advancement Act of 1995 (Pub L.
104-113, Sec. 12(d) (15 U.S.C. 272 Note)
Was the National Technology Transfer and Advancement Act Considered?
The rulemaking involves technical standards. Therefore, EPA
conducted a search to identify potentially applicable voluntary
consensus standards (VCS). However, we identified no such standards,
and none were brought to our attention in the comments, that would
ensure consistency throughout the regulated community. Our response-to-
comments document discusses this determination. Therefore, we have
decided to use the Air Methods contained in part 60, appendix A.
[[Page 53026]]
As noted in the proposed rule, the National Technology Transfer and
Advancement Act of 1995 (NTTAA) directs EPA to use voluntary consensus
standards in its regulatory activities unless to do so would be
inconsistent with applicable law or otherwise impractical. Voluntary
consensus standards are technical standards (e.g., materials
specifications, test methods, sampling procedures, and business
practices) that are developed or adopted by voluntary consensus
standards bodies. The NTTAA directs EPA to provide Congress, through
OMB, explanations when the Agency decides not to use available and
applicable voluntary consensus standards.
In the proposal, we discussed the manual emission test methods that
would be required for emission tests and calibration of continuous
emission monitors and relied heavily on the BIF methods in 40 CFR part
266, appendix IX. On December 30, 1997, we published a NODA which in
part questioned whether the task of determining the appropriate manual
method tests to be used for compliance should be simplified. The stack
sampling and analysis methods for hazardous waste combustors are under
the current BIF and incinerator rules for compliance tests (with a few
exceptions) that are located in SW-846. For compliance with the New
Source Performance Standard and other air rules, methods are located in
40 CFR part 60, appendix A. Potentially, you could be required to
perform two identical tests, one for compliance with MACT or RCRA and
one for compliance with other air rules, using identical test methods
simply because one method is an ``SW-846'' method and the other an
``air method.'' Further, the NODA stated that stack test methods
hazardous waste combustors use for compliance should be found in one
place to facilitate compliance. Therefore, we stated our intention to
reference 40 CFR part 60, appendix A (Except for dioxin/furans, where
we stated method 0023A of SW-846.), when it requires a specific stack-
sampling test method.
Since the time of the proposal, we instituted the ``Performance-
Based Measurement System.'' This system identifies performance related
criteria that can be used to evaluate alternative methods. Methods
determined to contain criteria or are a ``Methods-Based Parameters''
method are required, and are the only methods that can be used for
regulatory tests.
Commenters generally supported use of the Air Methods contained in
part 60, appendix A, or their ``SW-846'' equivalent. Furthermore,
because these methods were used to establish the final standards
contained in today's rulemaking, application of non approved methods
would result in unreliable and inconsistent measurements. Therefore,
today's rule will require the use of the Air Methods contained in part
60, appendix A. Section 63.7 describes procedures for the use of
alternative test methods for MACT sources. This procedure involves
using Method 301 of part 63, appendix A, to validate an alternate test
method and submitting the data to us. We then decide if the proposed
method is acceptable. Absent this approval under Sec. 63.7 procedures,
alternate methods cannot be used.
Today's rule, by requiring the use of only part 60, appendix A
methods (method 0023A of SW-846 for dioxin/furans) for compliance
determinations and particulate matter continuous emission monitor
correlations, would maintain national consistency with the selection of
specific manual stack sampling methods. We have determined that this
approach would facilitate ease of implementation with today's ``self
implementing'' MACT rule. Again, alternate methods may be approved by
the Administrator via the provisions of Sec. 63.7(f) and part Sec. 63,
appendix A, Method 301, Field Validation or Pollutant Measurement
Methods from Various Waste Media.
XIV. Executive Order 13084: Consultation and Coordination With Indian
Tribal Governments (63 FR 27655)
Were Tribal Government Issues Considered?
The requirements of section 3(b) of Executive Order 13084 do not
apply to this rule. They apply to rules that are not required by
statute, that significantly or uniquely affect the communities of
Indian tribal governments, and that impose substantial direct
compliance costs on those communities. EPA cannot issue those rules
unless the Federal government provides the funds necessary to pay the
direct compliance costs incurred by the tribal governments, or EPA
consults with those governments and gives required information to OMB.
But today's rule does not significantly or uniquely affect the
communities of Indian tribal governments.
For many of the same reasons described in the Unfunded Mandates
Reform Act discussion (section VI.C above), the requirements of
Executive Order 13084 do not apply to today's rule. Promulgation of
today's rule is under the statutory authority of the CAA. Also, while
Executive Order 13084 does not provide a specific gauge for determining
whether a regulation ``significantly or uniquely affects'' an Indian
tribal government, today's rule does not impose substantial direct
compliance costs on tribal governments and their communities. Tribal
communities are not predominantly located near hazardous waste
combustion facilities, when compared with other communities throughout
the nation. Finally, tribal governments will not be required to assume
any permitting responsibilities associated with this final rule because
permitting authority is voluntary for nonfederal government entities.
Shortly after forming the regulatory workgroup for this rulemaking
in April 1994, we looked for ways to obtain the input of state, local,
and tribal governments into the rulemaking process. As a result,
representatives from four State environmental agencies agreed to
participate in the workgroup. These representatives were asked to
consider the impacts of this rule of the state, local, and tribal
level. These representatives served on the workgroup until Final Agency
Review in November 1998. As members of the workgroup, they participated
in workgroup meetings and conference calls resulting in the development
of rulemaking issues and their solutions. They also provided written
comments on our work products on several occasions, including the
proposal, the May 1997 NODA, and the Final Agency Review package.
In their comments on the proposal and subsequent notices of data
availability, these representatives raised concerns over the following
issues:
--Use of site-specific risk assessments under RCRA
--Continuous emissions monitors
--Manual sampling methods
--Compliance schedule
--Use of test data to establish operating limits
--Automatic waste feed cutoffs
--Performance testing schedule
--Recordkeeping requirements
--Permitting issues
--Assessment of potential costs and benefits
--Human health benefits
--Area sources
--Notification and reporting requirements
--Protectiveness of human health as required by RCRA
--Redundant requirements
--State authorization
--Public participation
--CAAA and RCRA coordination
[[Page 53027]]
--Adequate public comment
--Implementation flexibility
--Allocation of grants
--And many other technical issues
We addressed the issues raised by these four representatives to the
fullest extent possible in today's rule. The comments received from
these representatives are included in the rulemaking docket, together
with all other comments received. We highlighted and addressed some of
these comments in today's preamble. We responded to all comments in the
Response to Comments document, which has been made available to the
Office of Management and Budget and is available in the docket for
today's rule.
Part Nine: Technical Amendments to Previous Regulations
I. Changes to the June 19, 1998 ``Fast-Track'' Rule
A. Permit Streamlining Section
Today's regulations correct a typographical error to Sec. 270.42
Appendix I entry L(9) promulgated in the Fast-track rule. Entry L(9)
incorrectly cited Sec. 270.42(i), whereas today's regulations correctly
amends entry L(9) to cite Sec. 270.42(j).
B. Comparable Fuels Section
In the June 19th rule, we explained that our methodology for
identifying the comparable fuels specifications was to select the
highest benchmark fuel value in our data base for each constituent (see
63 FR at 33786). However, the results reported in the final rule--Table
1 to Sec. 261.38--do not consistently follow our methodology. In
several instances, the highest value was not presented in the table, as
pointed out by commenters to the final rule. Therefore, in today's
rule, we are amending the comparable fuels portion of the Fast-track
rule to make necessary conforming changes to the comparable fuels
specifications as listed in Table 1 of Sec. 261.38--Detection and
Detection Limit Values for Comparable Fuel Specifications. Please see
the USEPA, ``Final Technical Support Document for HWC MACT Standards,
Volume 4'' July 1999, for a detailed discussion of the changes to Table
1.
In addition, because these are technical corrections (i.e.
corrections where we made arithmetic or other inadvertent mistakes in
applying our stated methodology for calculating the comparative fuel
levels) we find that giving notice and opportunity for public comment
is unnecessary within the meaning of 5 U.S.C. 553 (b) (B). In fact, the
errors were brought to our attention by an entity that applied the
stated methodology and derived the correct values which we are
restoring in this amendment. (We did, however, provide actual notice of
these intended corrections to entities we believed most interested in
the issue, so that these entities did have an opportunity for comment
to us.) For the same reasons, we find that there is good cause for the
rule to take effect immediately, rather than wait 30 days. See 5 U.S.C.
553 (d) (3). Finally, since notice and comment is unnecessary, this
correction is not a ``rule'' for purposes of the Regulatory Flexibility
Act (see 5 U.S.C. 601 (2)), and may take effect immediately before
submission to Congress for review (see 5 U.S.C. 808 (2)).
List of Subjects
40 CFR Part 60
Environmental protection, Administrative practice and procedure,
Air pollution control, Aluminum, Ammonium sulfate plants, Batteries,
Beverages, Carbon monoxide, Cement industry, Coal, Copper, Dry
cleaners, Electric power plants, Fertilizers, Fluoride, Gasoline, Glass
and glass products, Grains, Graphic arts industry, Heaters, Household
appliances, Insulation, Intergovernmental relations, Iron, Labeling,
Lead, Lime, Metallic and nonmetallic mineral processing plants, Metals,
Motor vehicles, Natural gas, Nitric acid plants, Nitrogen dioxide,
Paper and paper products industry, Particulate matter, Paving and
roofing materials, Petroleum, Phosphate, Plastics materials and
synthetics, Polymers, Reporting and recordkeeping requirements, Sewage
disposal, Steel, Sulfur oxides, Sulfuric acid plants, Tires, Urethane,
Vinyl, Volatile organic compounds, Waste treatment and disposal, Zinc.
40 CFR Part 63
Air pollution control, Hazardous substances, Incorporation by
Reference, Reporting and recordkeeping requirements
40 CFR Part 260
Administrative practice and procedure, Confidential business
information, Environmental protection, Hazardous waste.
40 CFR Part 261
Environmental Protection Hazardous waste, Recycling, Reporting and
recordkeeping requirements.
40 CFR Part 264
Air pollution control, Environmental protection, Hazardous waste,
Insurance, Packaging and containers, Reporting and recordkeeping
requirements, Security measures, Surety bonds.
40 CFR Part 265
Air pollution control, Environmental protection, Hazardous waste,
Insurance, Packaging and containers, Reporting and recordkeeping
requirements, Security measures, Surety bonds, Water supply.
40 CFR Part 266
Environmental protection, Energy, Hazardous waste, Recycling,
Reporting and recordkeeping requirements.
40 CFR Part 270
Administrative practice and procedure, Confidential business
information, Environmental Protection Agency, Hazardous materials
transportation, Hazardous waste, Reporting and recordkeeping
requirements, Water pollution control, Water supply.
40 CFR Part 271
Administrative practice and procedure, Confidential business
information, Environmental Protection Agency, Hazardous materials
transportation, Hazardous waste, Indians-lands, Intergovernmental
relations, Penalties, Reporting and recordkeeping requirements, Water
pollution control, Water supply.
Dated: July 30, 1999.
Carol M. Browner,
Administrator.
.For the reasons set out in the preamble, title 40 of the Code of
Federal Regulations is amended as follows:
PART 60--STANDARDS OF PERFORMANCE FOR NEW STATIONARY SOURCES
1. The authority citation for part 60 continues to read as follows:
Authority: 42 U.S.C. 7401-7601.
2. Appendix A to part 60 is amended by adding a new entry for
``Method 5I'' in numerical order to read as follows:
Appendix A--Test Methods
* * * * *
Method 5I--Determination of Low Level Particulate Matter Emissions From
Stationary Sources
Note: This method does not include all of the specifications
(e.g., equipment and supplies) and procedures (e.g., sampling and
analytical) essential to its performance. Certain information is
contained in other EPA procedures found in this part. Therefore, to
obtain reliable results, persons using this method should have
experience with and a thorough knowledge of the following Methods:
Methods 1, 2, 3, 4 and 5.
[[Page 53028]]
1. Scope and Application.
1.1 Analyte. Particulate matter (PM). No CAS number assigned.
1.2 Applicability. This method is applicable for the
determination of low level particulate matter (PM) emissions from
stationary sources. The method is most effective for total PM
catches of 50 mg or less. This method was initially developed for
performing correlation of manual PM measurements to PM continuous
emission monitoring systems (CEMS), however it is also useful for
other low particulate concentration applications.
1.3 Data Quality Objectives. Adherence to the requirements of
this method will enhance the quality of the data obtained from air
pollutant sampling methods. Method 5I requires the use of paired
trains. Acceptance criteria for the identification of data quality
outliers from the paired trains are provided in Section 12.2 of this
Method.
2. Summary of Method.
2.1. Description. The system setup and operation is essentially
identical to Method 5. Particulate is withdrawn isokinetically from
the source and collected on a 47 mm glass fiber filter maintained at
a temperature of 120 14 deg.C (248
25 deg.F). The PM mass is determined by gravimetric analysis after
the removal of uncombined water. Specific measures in this procedure
designed to improve system performance at low particulate levels
include:
1. Improved sample handling procedures
2 Light weight sample filter assembly
3. Use of low residue grade acetone
Accuracy is improved through the minimization of systemic errors
associated with sample handling and weighing procedures. High purity
reagents, all glass, grease free, sample train components, and light
weight filter assemblies and beakers, each contribute to the overall
objective of improved precision and accuracy at low particulate
concentrations.
2.2 Paired Trains. This method must be performed using a paired
train configuration. These trains may be operated as co-located
trains (to trains operating collecting from one port) or as
simultaneous trains (separate trains operating from different ports
at the same time). Procedures for calculating precision of the
paired trains are provided in Section 12.
2.3 Detection Limit. a. Typical detection limit for manual
particulate testing is 0.5 mg. This mass is also cited as the
accepted weight variability limit in determination of ``constant
weight'' as cited in Section 8.1.2 of this Method. EPA has performed
studies to provide guidance on minimum PM catch. The minimum
detection limit (MDL) is the minimum concentration or amount of an
analyte that can be determined with a specified degree of confidence
to be different from zero. We have defined the minimum or target
catch as a concentration or amount sufficiently larger than the MDL
to ensure that the results are reliable and repeatable. The
particulate matter catch is the product of the average particulate
matter concentration on a mass per volume basis and the volume of
gas collected by the sample train. The tester can generally control
the volume of gas collected by increasing the sampling time or to a
lesser extent by increasing the rate at which sample is collected.
If the tester has a reasonable estimate of the PM concentration from
the source, the tester can ensure that the target catch is collected
by sampling the appropriate gas volume.
b. However, if the source has a very low particulate matter
concentration in the stack, the volume of gas sampled may need to be
very large which leads to unacceptably long sampling times. When
determining compliance with an emission limit, EPA guidance has been
that the tester does not always have to collect the target catch.
Instead, we have suggested that the tester sample enough stack gas,
that if the source were exactly at the level of the emission
standard, the sample catch would equal the target catch. Thus, if at
the end of the test the catch were smaller than the target, we could
still conclude that the source is in compliance though we might not
know the exact emission level. This volume of gas becomes a target
volume that can be translated into a target sampling time by
assuming an average sampling rate. Because the MDL forms the basis
for our guidance on target sampling times, EPA has conducted a
systematic laboratory study to define what is the MDL for Method 5
and determined the Method to have a calculated practical
quantitation limit (PQL) of 3 mg of PM and an MDL of 1 mg.
c. Based on these results, the EPA has concluded that for PM
testing, the target catch must be no less than 3 mg. Those sample
catches between 1 mg and 3 mg are between the detection limit and
the limit of quantitation. If a tester uses the target catch to
estimate a target sampling time that results in sample catches that
are less than 3 mg, you should not automatically reject the results.
If the tester calculated the target sampling time as described above
by assuming that the source was at the level of the emission limit,
the results would still be valid for determining that the source was
in compliance. For purposes other than determining compliance,
results should be divided into two categories--those that fall
between 3 mg and 1 mg and those that are below 1 mg. A sample catch
between 1 and 3 mg may be used for such purposes as calculating
emission rates with the understanding that the resulting emission
rates can have a high degree of uncertainty. Results of less than 1
mg should not be used for calculating emission rates or pollutant
concentrations.
d. When collecting small catches such as 3 mg, bias becomes an
important issue. Source testers must use extreme caution to reach
the PQL of 3 mg by assuring that sampling probes are very clean
(perhaps confirmed by low blank weights) before use in the field.
They should also use low tare weight sample containers, and
establish a well-controlled balance room to weigh the samples.
3. Definitions.
3.1 Light Weight Filter Housing. A smaller housing that allows
the entire filtering system to be weighed before and after sample
collection. (See. 6.1.3)
3.2 Paired Train. Sample systems trains may be operated as co-
located trains (two sample probes attached to each other in the same
port) or as simultaneous trains (two separate trains operating from
different ports at the same time).
4. Interferences.
a. There are numerous potential interferents that may be
encountered during performance of Method 5I sampling and analyses.
This Method should be considered more sensitive to the normal
interferents typically encountered during particulate testing
because of the low level concentrations of the flue gas stream being
sampled.
b. Care must be taken to minimize field contamination,
especially to the filter housing since the entire unit is weighed
(not just the filter media). Care must also be taken to ensure that
no sample is lost during the sampling process (such as during port
changes, removal of the filter assemblies from the probes, etc.).
c. Balance room conditions are a source of concern for analysis
of the low level samples. Relative humidity, ambient temperatures
variations, air draft, vibrations and even barometric pressure can
affect consistent reproducible measurements of the sample media.
Ideally, the same analyst who performs the tare weights should
perform the final weights to minimize the effects of procedural
differences specific to the analysts.
d. Attention must also be provided to weighing artifacts caused
by electrostatic charges which may have to be discharged or
neutralized prior to sample analysis. Static charge can affect
consistent and reliable gravimetric readings in low humidity
environments. Method 5I recommends a relative humidity of less than
50 percent in the weighing room environment used for sample
analyses. However, lower humidity may be encountered or required to
address sample precision problems. Low humidity conditions can
increase the effects of static charge.
e. Other interferences associated with typical Method 5 testing
(sulfates, acid gases, etc.) are also applicable to Method 5I.
5. Safety.
Disclaimer. This method may involve hazardous materials,
operations, and equipment. This test method may not address all of
the safety concerns associated with its use. It is the
responsibility of the user to establish appropriate safety and
health practices and to determine the applicability and observe all
regulatory limitations before using this method.
6. Equipment and Supplies.
6.1 Sample Collection Equipment and Supplies. The sample train
is nearly identical in configuration to the train depicted in Figure
5-1 of Method 5. The primary difference in the sample trains is the
lightweight Method 5I filter assembly that attaches directly to the
exit to the probe. Other exceptions and additions specific to Method
5I include:
6.1.1 Probe Nozzle. Same as Method 5, with the exception that
it must be constructed of borosilicate or quartz glass tubing.
6.1.2 Probe Liner. Same as Method 5, with the exception that it
must be
[[Page 53029]]
constructed of borosilicate or quartz glass tubing.
6.1.3 Filter Holder. The filter holder is constructed of
borosilicate or quartz glass front cover designed to hold a 47-mm
glass fiber filter, with a wafer thin stainless steel (SS) filter
support, a silicone rubber or Viton O-ring, and Teflon tape seal.
This holder design will provide a positive seal against leakage from
the outside or around the filter. The filter holder assembly fits
into a SS filter holder and attaches directly to the outlet of the
probe. The tare weight of the filter, borosilicate or quartz glass
holder, SS filter support, O-ring and Teflon tape seal generally
will not exceed approximately 35 grams. The filter holder is
designed to use a 47-mm glass fiber filter meeting the quality
criteria in of Method 5. These units are commercially available from
several source testing equipment vendors. Once the filter holder has
been assembled, desiccated and tared, protect it from external
sources of contamination by covering the front socket with a ground
glass plug. Secure the plug with an impinger clamp or other item
that will ensure a leak-free fitting.
6.2 Sample Recovery Equipment and Supplies. Same as Method 5,
with the following exceptions:
6.2.1 Probe-Liner and Probe-Nozzle Brushes. Teflon
or nylon bristle brushes with stainless steel wire handles, should
be used to clean the probe. The probe brush must have extensions (at
least as long as the probe) of Teflon, nylon or similarly inert
material. The brushes must be properly sized and shaped for brushing
out the probe liner and nozzle.
6.2.2 Wash Bottles. Two Teflon wash bottles are recommended
however, polyethylene wash bottles may be used at the option of the
tester. Acetone should not be stored in polyethylene bottles for
longer than one month.
6.2.3 Filter Assembly Transport. A system should be employed to
minimize contamination of the filter assemblies during transport to
and from the field test location. A carrying case or packet with
clean compartments of sufficient size to accommodate each filter
assembly can be used. This system should have an air tight seal to
further minimize contamination during transport to and from the
field.
6.3 Analysis Equipment and Supplies. Same as Method 5, with the
following exception:
6.3.1 Lightweight Beaker Liner. Teflon or other lightweight
beaker liners are used for the analysis of the probe and nozzle
rinses. These light weight liners are used in place of the
borosilicate glass beakers typically used for the Method 5 weighings
in order to improve sample analytical precision.
6.3.2 Anti-static Treatment. Commercially available gaseous
anti-static rinses are recommended for low humidity situations that
contribute to static charge problems.
7. Reagents and Standards.
7.1 Sampling Reagents. The reagents used in sampling are the
same as Method 5 with the following exceptions:
7.1.1 Filters. The quality specifications for the filters are
identical to those cited for Method 5. The only difference is the
filter diameter of 47 millimeters.
7.1.2 Stopcock Grease. Stopcock grease cannot be used with this
sampling train. We recommend that the sampling train be assembled
with glass joints containing O-ring seals or screw-on connectors, or
similar.
7.1.3 Acetone. Low residue type acetone, 0.001
percent residue, purchased in glass bottles is used for the recovery
of particulate matter from the probe and nozzle. Acetone from metal
containers generally has a high residue blank and should not be
used. Sometimes, suppliers transfer acetone to glass bottles from
metal containers; thus, acetone blanks must be run prior to field
use and only acetone with low blank values (0.001 percent
residue, as specified by the manufacturer) must be used. Acetone
blank correction is not allowed for this method; therefore, it is
critical that high purity reagents be purchased and verified prior
to use.
7.1.4 Gloves. Disposable, powder-free, latex surgical gloves,
or their equivalent are used at all times when handling the filter
housings or performing sample recovery.
7.2 Standards. There are no applicable standards or audit
samples commercially available for Method 5I analyses.
8. Sample Collection, Preservation, Storage, and Transport.
8.1 Pretest Preparation. Same as Method 5 with several
exceptions specific to filter assembly and weighing.
8.1.1 Filter Assembly. Uniquely identify each filter support
before loading filters into the holder assembly. This can be done
with an engraving tool or a permanent marker. Use powder free latex
surgical gloves whenever handling the filter holder assemblies.
Place the O-ring on the back of the filter housing in the O-ring
groove. Place a 47 mm glass fiber filter on the O-ring with the face
down. Place a stainless steel filter holder against the back of the
filter. Carefully wrap 5 mm (\1/4\ inch) wide Teflon'' tape one
timearound the outside of the filter holder overlapping the
stainless steel filter support by approximately 2.5 mm (\1/8\ inch).
Gently brush the Teflon tape down on the back of the stainless steel
filter support. Store the filter assemblies in their transport case
until time for weighing or field use.
8.1.2 Filter Weighing Procedures. a. Desiccate the entire
filter holder assemblies at 20 5.6 deg.C (68
10 deg.F) and ambient pressure for at least 24 hours.
Weigh at intervals of at least 6 hours to a constant weight, i.e.,
0.5 mg change from previous weighing. Record the results to the
nearest 0.1 mg. During each weighing, the filter holder assemblies
must not be exposed to the laboratory atmosphere for a period
greater than 2 minutes and a relative humidity above 50 percent.
Lower relative humidity may be required in order to improve
analytical precision. However, low humidity conditions increase
static charge to the sample media.
b. Alternatively (unless otherwise specified by the
Administrator), the filters holder assemblies may be oven dried at
105 deg.C (220 deg.F) for a minimum of 2 hours, desiccated for 2
hours, and weighed. The procedure used for the tare weigh must also
be used for the final weight determination.
c. Experience has shown that weighing uncertainties are not only
related to the balance performance but to the entire weighing
procedure. Therefore, before performing any measurement, establish
and follow standard operating procedures, taking into account the
sampling equipment and filters to be used.
8.2 Preliminary Determinations. Select the sampling site,
traverse points, probe nozzle, and probe length as specified in
Method 5.
8.3 Preparation of Sampling Train. Same as Method 5, Section
8.3, with the following exception: During preparation and assembly
of the sampling train, keep all openings where contamination can
occur covered until justbefore assembly or until sampling is about
to begin. Using gloves, place a labeled (identified) and weighed
filter holder assembly into the stainless steel holder. Then place
this whole unit in the Method 5 hot box, and attach it to the probe.
Do not use stopcock grease.
8.4 Leak-Check Procedures. Same as Method 5.
8.5 Sampling Train Operation.
8.5.1. Operation. Operate the sampling train in a manner
consistent with those described in Methods 1, 2, 4 and 5 in terms of
the number of sample points and minimum time per point. The sample
rate and total gas volume should be adjusted based on estimated
grain loading of the source being characterized. The total sampling
time must be a function of the estimated mass of particulate to be
collected for the run. Targeted mass to be collected in a typical
Method 5I sample train should be on the order of 10 to 20 mg. Method
5I is most appropriate for total collected masses of less than 50
milligrams, however, there is not an exact particulate loading
cutoff, and it is likely that some runs may exceed 50 mg. Exceeding
50 mg (or less than 10 mg) for the sample mass does not necessarily
justify invalidating a sample run if all other Method criteria are
met.
8.5.2 Paired Train. This Method requires PM samples be
collected with paired trains.
8.5.2.1 It is important that the systems be operated truly
simultaneously. This implies that both sample systems start and stop
at the same times. This also means that if one sample system is
stopped during the run, the other sample systems must also be
stopped until the cause has been corrected.
8.5.2.2 Care should be taken to maintain the filter box
temperature of the paired trains as close as possible to the Method
required temperature of 120 14 deg.C (248
25 deg.F). If separate ovens are being used for simultaneously
operated trains, it is recommended that the oven temperature of each
train be maintained within 14 deg.C (
25 deg.F) of each other.
8.5.2.3 The nozzles for paired trains need not be identically
sized.
8.5.2.4 Co-located sample nozzles must be within the same plane
perpendicular to the gas flow. Co-located nozzles and pitot
assemblies should be within a 6.0 cm x 6.0 cm square (as cited for
a quadruple train in Reference Method 301).
8.5.3 Duplicate gas samples for molecular weight determination
need not be collected.
[[Page 53030]]
8.6 Sample Recovery. Same as Method 5 with several exceptions
specific to the filter housing.
8.6.1 Before moving the sampling train to the cleanup site,
remove the probe from the train and seal the nozzle inlet and outlet
of the probe. Be careful not to lose any condensate that might be
present. Cap the filter inlet using a standard ground glass plug and
secure the cap with an impinger clamp. Remove the umbilical cord
from the last impinger and cap the impinger. If a flexible line is
used between the first impinger condenser and the filter holder,
disconnect the line at the filter holder and let any condensed water
or liquid drain into the impingers or condenser.
8.6.2 Transfer the probe and filter-impinger assembly to the
cleanup area. This area must be clean and protected from the wind so
that the possibility of losing any of the sample will be minimized.
8.6.3 Inspect the train prior to and during disassembly and
note any abnormal conditions such as particulate color, filter
loading, impinger liquid color, etc.
8.6.4 Container No. 1, Filter Assembly. Carefully remove the
cooled filter holder assembly from the Method 5 hot box and place it
in the transport case. Use a pair of clean gloves to handle the
filter holder assembly.
8.6.5 Container No. 2, Probe Nozzle and Probe Liner Rinse.
Rinse the probe and nozzle components with acetone. Be certain that
the probe and nozzle brushes have been thoroughly rinsed prior to
use as they can be a source of contamination.
8.6.6 All Other Train Components. (Impingers) Same as Method 5.
8.7 Sample Storage and Transport. Whenever possible, containers
should be shipped in such a way that they remain upright at all
times. All appropriate dangerous goods shipping requirements must be
observed since acetone is a flammable liquid.
9. Quality Control.
9.1 Miscellaneous Field Quality Control Measures.
9.1.1 A quality control (QC) check of the volume metering
system at the field site is suggested before collecting the sample
using the procedures in Method 5, Section 4.4.1.
9.1.2 All other quality control checks outlined in Methods 1,
2, 4 and 5 also apply to Method 5I. This includes procedures such as
leak-checks, equipment calibration checks, and independent checks of
field data sheets for reasonableness and completeness.
9.2 Quality Control Samples.
9.2.1 Required QC Sample. A laboratory reagent blank must be
collected and analyzed for each lot of acetone used for a field
program to confirm that it is of suitable purity. The particulate
samples cannot be blank corrected.
9.2.2 Recommended QC Samples. These samples may be collected
and archived for future analyses.
9.2.2.1 A field reagent blank is a recommended QC sample
collected from a portion of the acetone used for cleanup of the
probe and nozzle. Take 100 ml of this acetone directly from the wash
bottle being used and place it in a glass sample container labeled
``field acetone reagent blank.'' At least one field reagent blank is
recommended for every five runs completed. The field reagent blank
samples demonstrate the purity of the acetone was maintained
throughout the program.
9.2.2.2 A field bias blank train is a recommended QC sample.
This sample is collected by recovering a probe and filter assembly
that has been assembled, taken to the sample location, leak checked,
heated, allowed to sit at the sample location for a similar duration
of time as a regular sample run, leak-checked again, and then
recovered in the same manner as a regular sample. Field bias blanks
are not a Method requirement, however, they are recommended and are
very useful for identifying sources of contamination in emission
testing samples. Field bias blank train results greater than 5 times
the method detection limit may be considered problematic.
10. Calibration and Standardization Same as Method 5, Section
5.
11. Analytical Procedures.
11.1 Analysis. Same as Method 5, Sections 11.1--11.2.4, with
the following exceptions:
11.1.1 Container No. 1. Same as Method 5, Section 11.2.1, with
the following exception: Use disposable gloves to remove each of the
filter holder assemblies from the desiccator, transport container,
or sample oven (after appropriate cooling).
11.1.2 Container No. 2. Same as Method 5, Section 11.2.2, with
the following exception: It is recommended that the contents of
Container No. 2 be transferred to a 250 ml beaker with a Teflon
liner or similar container that has a minimal tare weight before
bringing to dryness.
12. Data Analysis and Calculations.
12.1 Particulate Emissions. The analytical results cannot be
blank corrected for residual acetone found in any of the blanks. All
other sample calculations are identical to Method 5.
12.2 Paired Trains Outliers. a. Outliers are identified through
the determination of precision and any systemic bias of the paired
trains. Data that do not meet this criteria should be flagged as a
data quality problem. The primary reason for performing dual train
sampling is to generate information to quantify the precision of the
Reference Method data. The relative standard deviation (RSD) of
paired data is the parameter used to quantify data precision. RSD
for two simultaneously gathered data points is determined according
to:
[GRAPHIC] [TIFF OMITTED] TR30SE99.008
where, Ca and Cb are concentration values determined from trains A
and B respectively. For RSD calculation, the concentration units are
unimportant so long as they are consistent.
b. A minimum precision criteria for Reference Method PM data is
that RSD for any data pair must be less than 10% as long as the mean
PM concentration is greater than 10 mg/unit volume. If the mean PM
concentration is less than 10 mg/unit volume higher RSD values are
acceptable. At mean PM concentration of 1 mg/unit volume acceptable
RSD for paired trains is 25%. Between 1 and 10 mg/unit volume
acceptable RSD criteria should be linearly scaled from 25% to 10%.
Pairs of manual method data exceeding these RSD criteria should be
eliminated from the data set used to develop a PM CEMS correlation
or to assess RCA.
13. Method Performance. [Reserved]
14. Pollution Prevention. [Reserved]
15. Waste Management. [Reserved]
16. Alternative Procedures. Same as Method 5.
17. Bibliography. Same as Method 5.
18. Tables, Diagrams, Flowcharts and Validation Data. Figure 5I-
1 is a schematic of the sample train.
BILLING CODE 6560-50-P
[[Page 53031]]
[GRAPHIC] [TIFF OMITTED] TR30SE99.009
BILLING CODE 6560-50-C
[[Page 53032]]
3. Appendix B to part 60 is amended by adding Performance
Specifications 4B and 8A in numerical order to read as follows:
Appendix B--Performance Specifications
* * * * *
Performance Specification 4B---Specifications and test procedures
for carbon monoxide and oxygen continuous monitoring systems in
stationary sources
a. Applicability and Principle
1.1 Applicability. a. This specification is to be used for
evaluating the acceptability of carbon monoxide (CO) and oxygen
(O2) continuous emission monitoring systems (CEMS) at the
time of or soon after installation and whenever specified in the
regulations. The CEMS may include, for certain stationary sources,
(a) flow monitoring equipment to allow measurement of the dry volume
of stack effluent sampled, and (b) an automatic sampling system.
b. This specification is not designed to evaluate the installed
CEMS' performance over an extended period of time nor does it
identify specific calibration techniques and auxiliary procedures to
assess the CEMS' performance. The source owner or operator, however,
is responsible to properly calibrate, maintain, and operate the
CEMS. To evaluate the CEMS' performance, the Administrator may
require, under section 114 of the Act, the operator to conduct CEMS
performance evaluations at times other than the initial test.
c. The definitions, installation and measurement location
specifications, test procedures, data reduction procedures,
reporting requirements, and bibliography are the same as in PS 3
(for O2) and PS 4A (for CO) except as otherwise noted
below.
1.2 Principle. Installation and measurement location
specifications, performance specifications, test procedures, and
data reduction procedures are included in this specification.
Reference method tests, calibration error tests, calibration drift
tests, and interferant tests are conducted to determine conformance
of the CEMS with the specification.
b. Definitions
2.1 Continuous Emission Monitoring System (CEMS). This
definition is the same as PS 2 Section 2.1 with the following
addition. A continuous monitor is one in which the sample to be
analyzed passes the measurement section of the analyzer without
interruption.
2.2 Response Time. The time interval between the start of a
step change in the system input and when the pollutant analyzer
output reaches 95 percent of the final value.
2.3 Calibration Error (CE). The difference between the
concentration indicated by the CEMS and the known concentration
generated by a calibration source when the entire CEMS, including
the sampling interface is challenged. A CE test procedure is
performed to document the accuracy and linearity of the CEMS over
the entire measurement range.
3. Installation and Measurement Location Specifications
3.1 The CEMS Installation and Measurement Location. This
specification is the same as PS 2 Section 3.1 with the following
additions. Both the CO and O2 monitors should be
installed at the same general location. If this is not possible,
they may be installed at different locations if the effluent gases
at both sample locations are not stratified and there is no in-
leakage of air between sampling locations.
3.1.1 Measurement Location. Same as PS 2 Section 3.1.1.
3.1.2 Point CEMS. The measurement point should be within or
centrally located over the centroidal area of the stack or duct
cross section.
3.1.3 Path CEMS. The effective measurement path should: (1)
Have at least 70 percent of the path within the inner 50 percent of
the stack or duct cross sectional area, or (2) be centrally located
over any part of the centroidal area.
3.2 Reference Method (RM) Measurement Location and Traverse
Points. This specification is the same as PS 2 Section 3.2 with the
following additions. When pollutant concentration changes are due
solely to diluent leakage and CO and O2 are
simultaneously measured at the same location, one half diameter may
be used in place of two equivalent diameters.
3.3 Stratification Test Procedure. Stratification is defined as
the difference in excess of 10 percent between the average
concentration in the duct or stack and the concentration at any
point more than 1.0 meter from the duct or stack wall. To determine
whether effluent stratification exists, a dual probe system should
be used to determine the average effluent concentration while
measurements at each traverse point are being made. One probe,
located at the stack or duct centroid, is used as a stationary
reference point to indicate change in the effluent concentration
over time. The second probe is used for sampling at the traverse
points specified in Method 1 (40 CFR part 60 appendix A). The
monitoring system samples sequentially at the reference and traverse
points throughout the testing period for five minutes at each point.
d. Performance and Equipment Specifications
4.1 Data Recorder Scale. For O2, same as specified
in PS 3, except that the span must be 25 percent. The span of the
O2 may be higher if the O2 concentration at
the sampling point can be greater than 25 percent. For CO, same as
specified in PS 4A, except that the low-range span must be 200 ppm
and the high range span must be 3000 ppm. In addition, the scale for
both CEMS must record all readings within a measurement range with a
resolution of 0.5 percent.
4.2 Calibration Drift. For O2, same as specified in
PS 3. For CO, the same as specified in PS 4A except that the CEMS
calibration must not drift from the reference value of the
calibration standard by more than 3 percent of the span value on
either the high or low range.
4.3 Relative Accuracy (RA). For O2, same as
specified in PS 3. For CO, the same as specified in PS 4A.
4.4 Calibration Error (CE). The mean difference between the
CEMS and reference values at all three test points (see Table I)
must be no greater than 5 percent of span value for CO monitors and
0.5 percent for O2 monitors.
4.5 Response Time. The response time for the CO or
O2 monitor must not exceed 2 minutes.
e. Performance Specification Test Procedure
5.1 Calibration Error Test and Response Time Test Periods.
Conduct the CE and response time tests during the CD test period.
F. The CEMS Calibration Drift and Response Time Test Procedures
The response time test procedure is given in PS 4A, and must be
carried out for both the CO and O2 monitors.
7. Relative Accuracy and Calibration Error Test Procedures
7.1 Calibration Error Test Procedure. Challenge each monitor
(both low and high range CO and O2) with zero gas and EPA
Protocol 1 cylinder gases at three measurement points within the
ranges specified in Table I.
Table I. Calibration Error Concentration Ranges
------------------------------------------------------------------------
CO Low
Measurement point range CO High O2 (%)
(ppm) range (ppm)
------------------------------------------------------------------------
1................................. 0-40 0-600 0-2
2................................. 60-80 900-1200 8-10
3................................. 140-160 2100-2400 14-16
------------------------------------------------------------------------
Operate each monitor in its normal sampling mode as nearly as
possible. The calibration gas must be injected into the sample
system as close to the sampling probe outlet as practical and should
pass through all CEMS components used during normal sampling.
Challenge the CEMS three non-consecutive times at each measurement
point and record the responses. The duration of each gas
[[Page 53033]]
injection should be sufficient to ensure that the CEMS surfaces are
conditioned.
7.1.1 Calculations. Summarize the results on a data sheet.
Average the differences between the instrument response and the
certified cylinder gas value for each gas. Calculate the CE results
according to:
[GRAPHIC] [TIFF OMITTED] TR30SE99.010
where d is the mean difference between the CEMS response and the
known reference concentration and FS is the span value.
7.2 Relative Accuracy Test Procedure. Follow the RA test
procedures in PS 3 (for O2) section 3 and PS 4A (for CO)
section 4.
7.3 Alternative RA Procedure. Under some operating conditions,
it may not be possible to obtain meaningful results using the RA
test procedure. This includes conditions where consistent, very low
CO emission or low CO emissions interrupted periodically by short
duration, high level spikes are observed. It may be appropriate in
these circumstances to waive the RA test and substitute the
following procedure.
Conduct a complete CEMS status check following the
manufacturer's written instructions. The check should include
operation of the light source, signal receiver, timing mechanism
functions, data acquisition and data reduction functions, data
recorders, mechanically operated functions, sample filters, sample
line heaters, moisture traps, and other related functions of the
CEMS, as applicable. All parts of the CEMS must be functioning
properly before the RA requirement can be waived. The instrument
must also successfully passed the CE and CD specifications.
Substitution of the alternate procedure requires approval of the
Regional Administrator.
8. Bibliography
1. 40 CFR Part 266, Appendix IX, Section 2, ``Performance
Specifications for Continuous Emission Monitoring Systems.''
* * * * *
Performance Specification 8A--Specifications and test procedures for
total hydrocarbon continuous monitoring systems in stationary
sources
1. Applicability and Principle
1.1 Applicability. These performance specifications apply to
hydrocarbon (HC) continuous emission monitoring systems (CEMS)
installed on stationary sources. The specifications include
procedures which are intended to be used to evaluate the
acceptability of the CEMS at the time of its installation or
whenever specified in regulations or permits. The procedures are not
designed to evaluate CEMS performance over an extended period of
time. The source owner or operator is responsible for the proper
calibration, maintenance, and operation of the CEMS at all times.
1.2 Principle. A gas sample is extracted from the source
through a heated sample line and heated filter to a flame ionization
detector (FID). Results are reported as volume concentration
equivalents of propane. Installation and measurement location
specifications, performance and equipment specifications, test and
data reduction procedures, and brief quality assurance guidelines
are included in the specifications. Calibration drift, calibration
error, and response time tests are conducted to determine
conformance of the CEMS with the specifications.
2. Definitions
2.1 Continuous Emission Monitoring System (CEMS). The total
equipment used to acquire data, which includes sample extraction and
transport hardware, analyzer, data recording and processing
hardware, and software. The system consists of the following major
subsystems:
2.1.1 Sample Interface. That portion of the system that is used
for one or more of the following: Sample acquisition, sample
transportation, sample conditioning, or protection of the analyzer
from the effects of the stack effluent.
2.1.2 Organic Analyzer. That portion of the system that senses
organic concentration and generates an output proportional to the
gas concentration.
2.1.3 Data Recorder. That portion of the system that records a
permanent record of the measurement values. The data recorder may
include automatic data reduction capabilities.
2.2 Instrument Measurement Range. The difference between the
minimum and maximum concentration that can be measured by a specific
instrument. The minimum is often stated or assumed to be zero and
the range expressed only as the maximum.
2.3 Span or Span Value. Full scale instrument measurement
range. The span value must be documented by the CEMS manufacturer
with laboratory data.
2.4 Calibration Gas. A known concentration of a gas in an
appropriate diluent gas.
2.5 Calibration Drift (CD). The difference in the CEMS output
readings from the established reference value after a stated period
of operation during which no unscheduled maintenance, repair, or
adjustment takes place. A CD test is performed to demonstrate the
stability of the CEMS calibration over time.
2.6 Response Time. The time interval between the start of a
step change in the system input (e.g., change of calibration gas)
and the time when the data recorder displays 95 percent of the final
value.
2.7 Accuracy. A measurement of agreement between a measured
value and an accepted or true value, expressed as the percentage
difference between the true and measured values relative to the true
value. For these performance specifications, accuracy is checked by
conducting a calibration error (CE) test.
2.8 Calibration Error (CE). The difference between the
concentration indicated by the CEMS and the known concentration of
the cylinder gas. A CE test procedure is performed to document the
accuracy and linearity of the monitoring equipment over the entire
measurement range.
2.9 Performance Specification Test (PST) Period. The period
during which CD, CE, and response time tests are conducted.
2.10 Centroidal Area. A concentric area that is geometrically
similar to the stack or duct cross section and is no greater than 1
percent of the stack or duct cross-sectional area.
3. Installation and Measurement Location Specifications
3.1 CEMS Installation and Measurement Locations. The CEMS must
be installed in a location in which measurements representative of
the source's emissions can be obtained. The optimum location of the
sample interface for the CEMS is determined by a number of factors,
including ease of access for calibration and maintenance, the degree
to which sample conditioning will be required, the degree to which
it represents total emissions, and the degree to which it represents
the combustion situation in the firebox (where applicable). The
location should be as free from in-leakage influences as possible
and reasonably free from severe flow disturbances. The sample
location should be at least two equivalent duct diameters downstream
from the nearest control device, point of pollutant generation, or
other point at which a change in the pollutant concentration or
emission rate occurs and at least 0.5 diameter upstream from the
exhaust or control device. The equivalent duct diameter is
calculated as per 40 CFR part 60, appendix A, method 1, section 2.1.
If these criteria are not achievable or if the location is otherwise
less than optimum, the possibility of stratification should be
investigated as described in section 3.2. The measurement point must
be within the centroidal area of the stack or duct cross section.
3.2 Stratification Test Procedure. Stratification is defined as
a difference in excess of 10 percent between the average
concentration in the duct or stack and the concentration at any
point more than 1.0 meter from the duct or stack wall. To determine
whether effluent stratification exists, a dual probe system should
be used to determine the average effluent concentration while
measurements at each traverse point are being made. One probe,
located at the stack or duct centroid, is used as a stationary
reference point to indicate the change in effluent concentration
over time. The second probe is used for sampling at the traverse
points specified in 40 CFR part 60 appendix A, method 1. The
monitoring system samples sequentially at the reference and traverse
points throughout the testing period for five minutes at each point.
4. CEMS Performance and Equipment Specifications
If this method is applied in highly explosive areas, caution and
care must be exercised in choice of equipment and installation.
4.1 Flame Ionization Detector (FID) Analyzer. A heated FID
analyzer capable of meeting or exceeding the requirements of these
specifications. Heated systems must maintain the temperature of the
sample gas between 150 deg.C (300 deg.F) and 175 deg.C (350
deg.F) throughout the system. This requires all system components
such as the probe, calibration valve, filter, sample lines, pump,
and the FID to be kept heated at all times such that no moisture is
condensed out of the
[[Page 53034]]
system. The essential components of the measurement system are
described below:
4.1.1 Sample Probe. Stainless steel, or equivalent, to collect
a gas sample from the centroidal area of the stack cross-section.
4.1.2 Sample Line. Stainless steel or Teflon tubing to
transport the sample to the analyzer.
Note: Mention of trade names or specific products does not
constitute endorsement by the Environmental Protection Agency.
4.1.3 Calibration Valve Assembly. A heated three-way valve
assembly to direct the zero and calibration gases to the analyzer is
recommended. Other methods, such as quick-connect lines, to route
calibration gas to the analyzers are applicable.
4.1.4 Particulate Filter. An in-stack or out-of-stack sintered
stainless steel filter is recommended if exhaust gas particulate
loading is significant. An out-of-stack filter must be heated.
4.1.5 Fuel. The fuel specified by the manufacturer (e.g., 40
percent hydrogen/60 percent helium, 40 percent hydrogen/60 percent
nitrogen gas mixtures, or pure hydrogen) should be used.
4.1.6 Zero Gas. High purity air with less than 0.1 parts per
million by volume (ppm) HC as methane or carbon equivalent or less
than 0.1 percent of the span value, whichever is greater.
4.1.7 Calibration Gases. Appropriate concentrations of propane
gas (in air or nitrogen). Preparation of the calibration gases
should be done according to the procedures in EPA Protocol 1. In
addition, the manufacturer of the cylinder gas should provide a
recommended shelf life for each calibration gas cylinder over which
the concentration does not change by more than 2 percent
from the certified value.
4.2 CEMS Span Value. 100 ppm propane. The span value must be
documented by the CEMS manufacturer with laboratory data.
4.3 Daily Calibration Gas Values. The owner or operator must
choose calibration gas concentrations that include zero and high-
level calibration values.
4.3.1 The zero level may be between zero and 0.1 ppm (zero and
0.1 percent of the span value).
4.3.2 The high-level concentration must be between 50 and 90
ppm (50 and 90 percent of the span value).
4.4 Data Recorder Scale. The strip chart recorder, computer, or
digital recorder must be capable of recording all readings within
the CEMS' measurement range and must have a resolution of 0.5 ppm
(0.5 percent of span value).
4.5 Response Time. The response time for the CEMS must not
exceed 2 minutes to achieve 95 percent of the final stable value.
4.6 Calibration Drift. The CEMS must allow the determination of
CD at the zero and high-level values. The CEMS calibration response
must not differ by more than 3 ppm (3
percent of the span value) after each 24-hour period of the 7-day
test at both zero and high levels.
4.7 Calibration Error. The mean difference between the CEMS and
reference values at all three test points listed below must be no
greater than 5 ppm (5 percent of the span value).
4.7.1 Zero Level. Zero to 0.1 ppm (0 to 0.1 percent of span
value).
4.7.2 Mid-Level. 30 to 40 ppm (30 to 40 percent of span value).
4.7.3 High-Level. 70 to 80 ppm (70 to 80 percent of span
value).
4.8 Measurement and Recording Frequency. The sample to be
analyzed must pass through the measurement section of the analyzer
without interruption. The detector must measure the sample
concentration at least once every 15 seconds. An average emission
rate must be computed and recorded at least once every 60 seconds.
4.9 Hourly Rolling Average Calculation. The CEMS must calculate
every minute an hourly rolling average, which is the arithmetic mean
of the 60 most recent 1-minute average values.
4.10 Retest. If the CEMS produces results within the specified
criteria, the test is successful. If the CEMS does not meet one or
more of the criteria, necessary corrections must be made and the
performance tests repeated.
5. Performance Specification Test (PST) Periods
5.1 Pretest Preparation Period. Install the CEMS, prepare the
PTM test site according to the specifications in section 3, and
prepare the CEMS for operation and calibration according to the
manufacturer's written instructions. A pretest conditioning period
similar to that of the 7-day CD test is recommended to verify the
operational status of the CEMS.
5.2 Calibration Drift Test Period. While the facility is
operating under normal conditions, determine the magnitude of the CD
at 24-hour intervals for seven consecutive days according to the
procedure given in section 6.1. All CD determinations must be made
following a 24-hour period during which no unscheduled maintenance,
repair, or adjustment takes place. If the combustion unit is taken
out of service during the test period, record the onset and duration
of the downtime and continue the CD test when the unit resumes
operation.
5.3 Calibration Error Test and Response Time Test Periods.
Conduct the CE and response time tests during the CD test period.
6. Performance Specification Test Procedures
6.1 Relative Accuracy Test Audit (RATA) and Absolute
Calibration Audits (ACA). The test procedures described in this
section are in lieu of a RATA and ACA.
6.2 Calibration Drift Test.
6.2.1 Sampling Strategy. Conduct the CD test at 24-hour
intervals for seven consecutive days using calibration gases at the
two daily concentration levels specified in section 4.3. Introduce
the two calibration gases into the sampling system as close to the
sampling probe outlet as practical. The gas must pass through all
CEM components used during normal sampling. If periodic automatic or
manual adjustments are made to the CEMS zero and calibration
settings, conduct the CD test immediately before these adjustments,
or conduct it in such a way that the CD can be determined. Record
the CEMS response and subtract this value from the reference
(calibration gas) value. To meet the specification, none of the
differences may exceed 3 percent of the span of the CEM.
6.2.2 Calculations. Summarize the results on a data sheet. An
example is shown in Figure 1. Calculate the differences between the
CEMS responses and the reference values.
6.3 Response Time. The entire system including sample
extraction and transport, sample conditioning, gas analyses, and the
data recording is checked with this procedure.
6.3.1 Introduce the calibration gases at the probe as near to
the sample location as possible. Introduce the zero gas into the
system. When the system output has stabilized (no change greater
than 1 percent of full scale for 30 sec), switch to monitor stack
effluent and wait for a stable value. Record the time (upscale
response time) required to reach 95 percent of the final stable
value.
6.3.2 Next, introduce a high-level calibration gas and repeat
the above procedure. Repeat the entire procedure three times and
determine the mean upscale and downscale response times. The longer
of the two means is the system response time.
6.4 Calibration Error Test Procedure.
6.4.1 Sampling Strategy. Challenge the CEMS with zero gas and
EPA Protocol 1 cylinder gases at measurement points within the
ranges specified in section 4.7.
6.4.1.1 The daily calibration gases, if Protocol 1, may be used
for this test.
BILLING CODE 6560-50-P
[[Page 53035]]
[GRAPHIC] [TIFF OMITTED] TR30SE99.011
BILLING CODE 6560-50-C
[[Page 53036]]
6.4.1.2 Operate the CEMS as nearly as possible in its normal
sampling mode. The calibration gas should be injected into the
sampling system as close to the sampling probe outlet as practical
and must pass through all filters, scrubbers, conditioners, and
other monitor components used during normal sampling. Challenge the
CEMS three non-consecutive times at each measurement point and
record the responses. The duration of each gas injection should be
for a sufficient period of time to ensure that the CEMS surfaces are
conditioned.
6.4.2 Calculations. Summarize the results on a data sheet. An
example data sheet is shown in Figure 2. Average the differences
between the instrument response and the certified cylinder gas value
for each gas. Calculate three CE results according to Equation 1. No
confidence coefficient is used in CE calculations.
7. Equations
Calibration Error. Calculate CE using Equation 1.
[GRAPHIC] [TIFF OMITTED] TR30SE99.012
Where:
d= Mean difference between CEMS response and the known reference
concentration, determined using Equation 2.
[GRAPHIC] [TIFF OMITTED] TR30SE99.013
Where:
di = Individual difference between CEMS response and the
known reference concentration.
8. Reporting
At a minimum, summarize in tabular form the results of the CD,
response time, and CE test, as appropriate. Include all data sheets,
calculations, CEMS data records, and cylinder gas or reference
material certifications.
BILLING CODE 6560-50-P
[[Page 53037]]
[GRAPHIC] [TIFF OMITTED] TR30SE99.014
BILLING CODE 6560-50-C
[[Page 53038]]
9. References
1. Measurement of Volatile Organic Compounds-Guideline Series.
U.S. Environmental Protection Agency, Research Triangle Park, North
Carolina, 27711, EPA-450/2-78-041, June 1978.
2. Traceability Protocol for Establishing True Concentrations of
Gases Used for Calibration and Audits of Continuous Source Emission
Monitors (Protocol No. 1). U.S. Environmental Protection Agency ORD/
EMSL, Research Triangle Park, North Carolina, 27711, June 1978.
3. Gasoline Vapor Emission Laboratory Evaluation-Part 2. U.S.
Environmental Protection Agency, OAQPS, Research Triangle Park,
North Carolina, 27711, EMB Report No. 76-GAS-6, August 1975.
* * * * *
PART 63--NATIONAL EMISSION STANDARDS FOR HAZARDOUS AIR POLLUTANTS
FOR SOURCE CATEGORIES
1. The authority citation for part 63 continues to read as follows:
Authority: 42 U.S.C. 7401 et seq.
2. Part 63, subpart EEE, is revised to read as follows:
Subpart EEE--National Emission Standards for Hazardous Air
Pollutants from Hazardous Waste Combustors
General
Sec.
63.1200 Who is subject to these regulations?
63.1201 Definitions and acronyms used in this subpart.
63.1202 [Reserved]
Emissions Standards and Operating Limits
63.1203 What are the standards for hazardous waste incinerators?
63.1204 What are the standards for hazardous waste burning cement
kilns?
63.1205 What are the standards for hazardous waste burning
lightweight aggregate kilns?
Monitoring and Compliance Provisions
63.1206 When and how must you comply with the standards and
operating requirements?
63.1207 What are the performance testing requirements?
63.1208 What are the test methods?
63.1209 What are the monitoring requirements?
Notification, Reporting and Recordkeeping
63.1210 What are the notification requirements?
63.1211 What are the recordkeeping and reporting requirements?
63.1212 What are the other requirements pertaining to the NIC and
associated progress reports?
Other
63.1213 How can the compliance date be extended to install
pollution prevention or waste minimization controls?
Table 1 to Subpart EEE of Part 63--General Provisions Applicable to
Subpart EEE
Appendix A to Subpart EEE--Quality Assurance Procedures for
Continuous Emissions Monitors Used for Hazardous Waste Combustors
Subpart EEE--National Emission Standards for Hazardous Air
Pollutants from Hazardous Waste Combustors General
Sec. 63.1200 Who is subject to these regulations?
The provisions of this subpart apply to all hazardous waste
combustors: hazardous waste incinerators, hazardous waste burning
cement kilns, and hazardous waste burning lightweight aggregate kilns,
except as provided in Table 1 of this section. Hazardous waste
combustors are also subject to applicable requirements under parts 260-
270 of this chapter.
(a) What if I am an area source? (1) Both area sources and major
sources are subject to this subpart.
(2) Both area sources and major sources, not previously subject to
title V, are immediately subject to the requirement to apply for and
obtain a title V permit in all States, and in areas covered by part 71
of this chapter.
(b) These regulations in this subpart do not apply to sources
that meet the criteria in Table 1 of this Section, as follows:
Table 1 to Sec. 63.1200.-- Hazardous Waste Combustors Exempt from
Subpart EEE
------------------------------------------------------------------------
If And if Then
------------------------------------------------------------------------
(1) You are a previously (i) You ceased You are no longer
affected source. feeding hazardous subject to this
waste for a subpart (Subpart
period of time EEE).
greater than the
hazardous waste
residence time
(i.e., hazardous
waste no longer
resides in the
combustion
chamber);.
(ii) You are in
compliance with
the closure
requirements of
subpart G, parts
264 or 265 of
this chapter;.
(iii) You begin
complying with
the requirements
of all other
applicable
standards of this
part (Part 63);
and.
(iv) You notify
the Administrator
in writing that
you are no longer
an affected
source under this
subpart (Subpart
EEE).
(2) You are a research, You operate for no You are not
development, and demonstration longer than one subject to this
source. year after first subpart (Subpart
burning hazardous EEE). This
waste (Note that exemption applies
the Administrator even if there is
can extent this a hazardous waste
one-year combustor at the
restriction on a plant site that
case-by-case is regulated
basis upon your under this
written request subpart. You
documenting when still, however,
you first burned remain subject to
hazardous waste Sec. 270.65 of
and the this chapter.
justification for
needing
additional time
to perform
research,
development, or
demonstration
operations.).
(3) The only hazardous wastes ................ You are not
you burn are exempt from subject to the
regulation under Sec. requirements of
266.100(b) of this chapter. this subpart
(Subpart EEE).
------------------------------------------------------------------------
[[Page 53039]]
(c) Table 1 of this section specifies the provisions of subpart A
(General Provisions, Secs. 63.1-63.15) that apply and those that do not
apply to sources affected by this subpart.
Sec. 63.1201 Definitions and acronyms used in this subpart.
(a) The terms used in this subpart are defined in the Act, in
subpart A of this part, or in this section as follows:
Air pollution control system means the equipment used to reduce the
release of particulate matter and other pollutants to the atmosphere.
Automatic waste feed cutoff (AWFCO) system means a system comprised
of cutoff valves, actuator, sensor, data manager, and other necessary
components and electrical circuitry designed, operated and maintained
to stop the flow of hazardous waste to the combustion unit
automatically and immediately (except as provided by
Sec. 63.1206(c)(2)(viii)) when any operating requirement is exceeded.
By-pass duct means a device which diverts a minimum of 10 percent
of a cement kiln's off gas, or a device which the Administrator
determines on a case-by-case basis diverts a sample of kiln gas that
contains levels of carbon monoxide or hydrocarbons representative of
the levels in the kiln.
Combustion chamber means the area in which controlled flame
combustion of hazardous waste occurs.
Continuous monitor means a device which continuously samples the
regulated parameter specified in Sec. 63.1209 without interruption,
evaluates the detector response at least once every 15 seconds, and
computes and records the average value at least every 60 seconds,
except during allowable periods of calibration and except as defined
otherwise by the CEMS Performance Specifications in appendix B, part 60
of this chapter.
Dioxin/furan and dioxins and furans mean tetra-, penta-, hexa-,
hepta-, and octa-chlorinated dibenzo dioxins and furans.
Existing source means any affected source that is not a new source.
Feedrate operating limits means limits on the feedrate of materials
(e.g., metals, chlorine) to the combustor that are established based on
comprehensive performance testing. The limits are established and
monitored by knowing the concentration of the limited material (e.g.,
chlorine) in each feedstream and the flowrate of each feedstream.
Feedstream means any material fed into a hazardous waste combustor,
including, but not limited to, any pumpable or nonpumpable solid,
liquid, or gas.
Flowrate means the rate at which a feedstream is fed into a
hazardous waste combustor.
Hazardous waste is defined in Sec. 261.3 of this chapter.
Hazardous waste burning cement kiln means a rotary kiln and any
associated preheater or precalciner devices that produce clinker by
heating limestone and other materials for subsequent production of
cement for use in commerce, and that burns hazardous waste at any time.
Hazardous waste combustor means a hazardous waste incinerator,
hazardous waste burning cement kiln, or hazardous waste burning
lightweight aggregate kiln.
Hazardous waste incinerator means a device defined as an
incinerator in Sec. 260.10 of this chapter and that burns hazardous
waste at any time.
Hazardous waste lightweight aggregate kiln means a rotary kiln that
produces clinker by heating materials such as slate, shale and clay for
subsequent production of lightweight aggregate used in commerce, and
that burns hazardous waste at any time.
Hazardous waste residence time means the time elapsed from cutoff
of the flow of hazardous waste into the combustor (including, for
example, the time required for liquids to flow from the cutoff valve
into the combustor) until solid, liquid, and gaseous materials from the
hazardous waste, excluding residues that may adhere to combustion
chamber surfaces, exit the combustion chamber. For combustors with
multiple firing systems whereby the residence time may vary for the
firing systems, the hazardous waste residence time for purposes of
complying with this subpart means the longest residence time for any
firing system in use at the time of waste cutoff.
Initial comprehensive performance test means the comprehensive
performance test that is used as the basis for initially demonstrating
compliance with the standards.
In-line kiln raw mill means a hazardous waste burning cement kiln
design whereby kiln gas is ducted through the raw material mill for
portions of time to facilitate drying and heating of the raw material.
Instantaneous monitoring means continuously sampling, detecting,
and recording the regulated parameter without use of an averaging
period.
Monovent means an exhaust configuration of a building or emission
control device (e.g. positive pressure fabric filter) that extends the
length of the structure and has a width very small in relation to its
length (i.e., length to width ratio is typically greater than 5:1). The
exhaust may be an open vent with or without a roof, louvered vents, or
a combination of such features.
MTEC means maximum theoretical emissions concentration of metals or
HCl/Cl, expressed as g/dscm, and is calculated by dividing the
feedrate by the gas flowrate.
New source means any affected source the construction or
reconstruction of which is commenced after April 19, 1996.
One-minute average means the average of detector responses
calculated at least every 60 seconds from responses obtained at least
every 15 seconds.
Operating record means a documentation retained at the facility for
ready inspection by authorized officials of all information required by
the standards to document and maintain compliance with the applicable
regulations, including data and information, reports, notifications,
and communications with regulatory officials.
Operating requirements means operating terms or conditions, limits,
or operating parameter limits developed under this subpart that ensure
compliance with the emission standards.
Raw material feed means the prepared and mixed materials, which
include but are not limited to materials such as limestone, clay,
shale, sand, iron ore, mill scale, cement kiln dust and flyash, that
are fed to a cement or lightweight aggregate kiln. Raw material feed
does not include the fuels used in the kiln to produce heat to form the
clinker product.
Research, development, and demonstration source means a source
engaged in laboratory, pilot plant, or prototype demonstration
operations:
(1) Whose primary purpose is to conduct research, development, or
short-term demonstration of an innovative and experimental hazardous
waste treatment technology or process; and
(2) Where the operations are under the close supervision of
technically-trained personnel.
Rolling average means the average of all one-minute averages over
the averaging period.
Run means the net period of time during which an air emission
sample is collected under a given set of operating conditions. Three or
more runs constitutes a test. Unless otherwise specified, a run may be
either intermittent or continuous.
Run average means the average of the one-minute average parameter
values for a run.
TEQ means toxicity equivalence, the international method of
relating the toxicity of various dioxin/furan congeners to the toxicity
of 2,3,7,8-tetrachlorodibenzo-p-dioxin.
[[Page 53040]]
You means the owner or operator of a hazardous waste combustor.
(b) The acronyms used in this subpart refer to the following:
AWFCO means automatic waste feed cutoff.
CAS means chemical abstract services registry.
CEMS means continuous emissions monitoring system.
CMS means continuous monitoring system.
DRE means destruction and removal efficiency.
MACT means maximum achievable control technology.
MTEC means maximum theoretical emissions concentration.
NIC means notification of intent to comply.
Sec. 63.1202 [Reserved]
Emissions Standards and Operating Limits
Sec. 63.1203 What are the standards for hazardous waste incinerators?
(a) Emission limits for existing sources You must not discharge or
cause combustion gasses to be emitted into the atmosphere that contain:
(1) For dioxins and furans:
(i) Emissions in excess of 0.20 ng TEQ/dscm corrected to 7 percent
oxygen; or
(ii) Emissions in excess of 0.40 ng TEQ/dscm corrected to 7 percent
oxygen provided that the combustion gas temperature at the inlet to the
initial particulate matter control device is 400 deg.F or lower based
on the average of the test run average temperatures; \1\
---------------------------------------------------------------------------
\1\ For purposes of compliance, operation of a wet particulate
control device is presumed to meet the 400 deg.F or lower
requirement.
---------------------------------------------------------------------------
(2) Mercury in excess of 130 g/dscm corrected to 7 percent
oxygen;
(3) Lead and cadmium in excess of 240 ``g/dscm, combined emissions,
corrected to 7 percent oxygen;
(4) Arsenic, beryllium, and chromium in excess of 97 ``g/dscm,
combined emissions, corrected to 7 percent oxygen;
(5) For carbon monoxide and hydrocarbons, either:
(i) Carbon monoxide in excess of 100 parts per million by volume,
over an hourly rolling average (monitored continuously with a
continuous emissions monitoring system), dry basis and corrected to 7
percent oxygen, and hydrocarbons in excess of 10 parts per million by
volume over an hourly rolling average (monitored continuously with a
continuous emissions monitoring system), dry basis, corrected to 7
percent oxygen, and reported as propane, at any time during the
destruction and removal efficiency (DRE) test runs or their equivalent
as provided by Sec. 63.1206(b)(7); or
(ii) Hydrocarbons in excess of 10 parts per million by volume, over
an hourly rolling average (monitored continuously with a continuous
emissions monitoring system), dry basis, corrected to 7 percent oxygen,
and reported as propane;
(6) Hydrochloric acid and chlorine gas in excess of 77 parts per
million by volume, combined emissions, expressed as hydrochloric acid
equivalents, dry basis and corrected to 7 percent oxygen; and
(7) Particulate matter in excess of 34 mg/dscm corrected to 7
percent oxygen.
(b) Emission limits for new sources. You must not discharge or
cause combustion gases to be emitted into the atmosphere that contain:
(1) Dioxins and furans in excess of 0.20 ng TEQ/dscm, corrected to
7 percent oxygen;
(2) Mercury in excess of 45 g/dscm corrected to 7 percent
oxygen;
(3) Lead and cadmium in excess of 24 g/dscm, combined
emissions, corrected to 7 percent oxygen;
(4) Arsenic, beryllium, and chromium in excess of 97 g/
dscm, combined emissions, corrected to 7 percent oxygen;
(5) For carbon monoxide and hydrocarbons, either:
(i) Carbon monoxide in excess of 100 parts per million by volume,
over an hourly rolling average (monitored continuously with a
continuous emissions monitoring system), dry basis and corrected to 7
percent oxygen, and hydrocarbons in excess of 10 parts per million by
volume over an hourly rolling average (monitored continuously with a
continuous emissions monitoring system), dry basis, corrected to 7
percent oxygen, and reported as propane, at any time during the
destruction and removal efficiency (DRE) test runs or their equivalent
as provided by Sec. 63.1206(b)(7); or
(ii) Hydrocarbons in excess of 10 parts per million by volume, over
an hourly rolling average (monitored continuously with a continuous
emissions monitoring system), dry basis, corrected to 7 percent oxygen,
and reported as propane;
(6) Hydrochloric acid and chlorine gas in excess of 21 parts per
million by volume, combined emissions, expressed as hydrochloric acid
equivalents, dry basis and corrected to 7 percent oxygen; and
(7) Particulate matter in excess of 34 mg/dscm corrected to 7
percent oxygen.
(c) Destruction and removal efficiency (DRE) standard. (1) 99.99%
DRE. Except as provided in paragraph (c)(2) of this section, you must
achieve a destruction and removal efficiency (DRE) of 99.99% for each
principle organic hazardous constituent (POHC) designated under
paragraph (c)(3) of this section. You must calculate DRE for each POHC
from the following equation:
[GRAPHIC] [TIFF OMITTED] TR30SE99.015
Where:
Win=mass feedrate of one principal organic hazardous
constituent (POHC) in a waste feedstream; and
Wout=mass emission rate of the same POHC present in exhaust
emissions prior to release to the atmosphere
(2) 99.9999% DRE. If you burn the dioxin-listed hazardous wastes
FO20, FO21, FO22, FO23, FO26, or FO27 (see Sec. 261.31 of this
chapter), you must achieve a destruction and removal efficiency (DRE)
of 99.9999% for each principle organic hazardous constituent (POHC)
that you designate under paragraph (c)(3) of this section. You must
demonstrate this DRE performance on POHCs that are more difficult to
incinerate than tetro-, penta-, and hexachlorodibenzo-p-dioxins and
dibenzofurans. You must use the equation in paragraph (c)(1) of this
section calculate DRE for each POHC. In addition, you must notify the
Administrator of your intent to incinerate hazardous wastes FO20, FO21,
FO22, FO23, FO26, or FO27.
(3) Principal organic hazardous constituents (POHCs). (i) You must
treat the Principal Organic Hazardous Constituents (POHCs) in the waste
feed that you specify under paragraph (c)(3)(ii) of this section to the
extent required by paragraphs (c)(1) and (c)(2) of this section.
(ii) You must specify one or more POHCs from the list of hazardous
air pollutants established by 42 U.S.C. 7412(b)(1), excluding
caprolactam (CAS number 105602) as provided by Sec. 63.60, for each
waste to be burned. You must base this specification on the degree of
difficulty of incineration of the organic constituents in the waste and
on their concentration or mass in the waste feed, considering the
results of waste analyses or other data and information.
(d) Significant figures. The emission limits provided by paragraphs
(a) and (b) of this section are presented with two significant figures.
Although you must perform intermediate calculations using at least
three significant figures, you may round the resultant emission levels
to two significant figures to document compliance.
[[Page 53041]]
(e) Air emission standards for equipment leaks, tanks, surface
impoundments, and containers. You are subject to the air emission
standards of subparts BB and CC, part 264, of this chapter.
Sec. 63.1204 What are the standards for hazardous waste burning cement
kilns?
(a) Emission limits for existing sources. You must not discharge or
cause combustion gases to be emitted into the atmosphere that contain:
(1) For dioxins and furans:
(i) Emissions in excess of 0.20 ng TEQ/dscm corrected to 7 percent
oxygen; or
(ii) Emissions in excess of 0.40 ng TEQ/dscm corrected to 7 percent
oxygen provided that the combustion gas temperature at the inlet to the
initial dry particulate matter control device is 400 deg.F or lower
based on the average of the test run average temperatures;
(2) Mercury in excess of 120 g/dscm corrected to 7 percent
oxygen;
(3) Lead and cadmium in excess of 240