97-11155. Revised Technical Standards for Hazardous Waste Combustion Facilities

[Federal Register Volume 62, Number 85 (Friday, May 2, 1997)]
[Proposed Rules]
[Pages 24212-24254]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 97-11155]

[[Page 24211]]

_______________________________________________________________________

Part III

Environmental Protection Agency

_______________________________________________________________________

40 CFR Part 60, et al.

Revised Technical Standards for Hazardous Waste Combustion Facilities;
Proposed Rule

Federal Register / Vol. 62, No. 85 / Friday, May 2, 1997 / Proposed
Rules

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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Parts 60, 63, 260, 261, 264, 265, 266, 270, and 271

[FRL-5818-9]

Revised Technical Standards for Hazardous Waste Combustion
Facilities

AGENCY: Environmental Protection Agency (EPA).

ACTION: Notice of data availability and request for comments.

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SUMMARY: This document is a notice of availability and invitation for
comment on the following information pertaining to the proposed revised
standards for hazardous waste combustors (61 FR 17358 (April 19,
1996)): Report on the status of setting national emission standards for
hazardous air pollutants (NESHAPS) based on the revised emissions
database; Report on the selection of pollutants and source categories,
including area and major sources; report on the status of various
implementation issues, including compliance dates, compliance
requirements, performance testing, and notification and reporting
requirements; and report on the status of permit requirements,
including waste minimization incentives.

DATES: Written comments must be submitted by June 2, 1997.

ADDRESSES: Commenters must send an original and two copies of their
comments referencing docket number F-97-CS4A-FFFFF to: RCRA Docket
Information Center, Office of Solid Waste (5305G), U.S. Environmental
Protection Agency Headquarters (EPA, HQ), 401 M Street, SW.,
Washington, DC 20460. Deliveries of comments should be made to the
Arlington, Virginia address listed below. Comments may also be
submitted electronically through the Internet to: docket@epamail.epa.gov. Comments in electronic format should also be
identified by the docket number F-97-CS4A-FFFFF. All electronic
comments must be submitted as an ASCII file avoiding the use of special
characters and any form of encryption. For other information regarding
submitting comments electronically or viewing the comments received or
supporting information, please refer to the proposed rule (61 FR 17358
(April 19, 1996)).
Commenters should not submit electronically any confidential
business information (CBI). An original and two copies of the CBI must
be submitted under separate cover to: RCRA CBI Document Control
Officer, Office of Solid Waste (5305W), U.S. EPA, 401 M Street, SW.,
Washington, DC 20460.
Public comments and supporting materials are available for viewing
in the RCRA Information Center (RIC), located at Crystal Gateway One,
1235 Jefferson Davis Highway, First Floor, Arlington, Virginia. The RIC
is open from 9 a.m. to 4 p.m., Monday through Friday, except for
Federal holidays. To review docket materials, the public must make an
appointment by calling 703-603-9230. The public may copy a maximum of
100 pages from any regulatory docket at no charge. Additional copies
cost $0.15 per page.

FOR FURTHER INFORMATION CONTACT: For general information, 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. The RCRA Hotline is open Monday-Friday, 9 a.m. to 6
p.m., Eastern Standard Time. The RCRA Hotline can also provide
directions on how to access electronically some of the documents and
data referred to in this notice via EPA's Cleanup Information Bulletin
Board System (CLU-IN). The CLU-IN modem access phone number is 301-589-
8366, or Telnet to clu-in.epa.gov for Internet access. The files posted
on CLU-IN are in Portable Document Format (PDF) and can be viewed and
printed using Acrobat Reader.
For more detailed information on specific aspects of this notice,
contact Larry Denyer, Office of Solid Waste (5302W), U.S. Environmental
Protection Agency, 401 M Street, SW., Washington, DC 20460, 703-308-
8770, e-mail address: denyer.larry@epamail.epa.gov.

SUPPLEMENTARY INFORMATION:

The Agency specifically solicits comment on the following
documents:
(1) Draft Technical Support Document for HWC MACT Standards (NODA),
Volume I: MACT Evaluations Based on Revised Database, April 1997.
(2) Draft Technical Support Document for HWC MACT Standards (NODA),
Volume II: Evaluation of CO/HC and DRE Database, April 1997.
(3) Draft Technical Support Document for HWC MACT Standards (NODA),
Volume III: Evaluation of Metals Emissions Database to Investigate
Extrapolation and Interpolation Issues, April 1997.
In preparing this notice, the Agency considered comments on the
proposed rule, including those listed below. EPA is soliciting
responsive comments regarding certain data and information presented in
these comments:
(1) Cement Kiln Recycling Coalition
(2) Chemical Manufacturers Association
(3) Coalition for Responsible Waste Incineration
(4) Don Clay Associates
(5) The Dow Chemical Company
(6) Environmental Technology Council
(7) Holnam Inc.
(8) Lafarge Corporation
(9) Molten Metal Technology, Inc.
(10) The Natural Resources Defense Council, Inc.
(11) Rollins Environmental Services, Inc.
(12) Safety-Kleen Corp.
(13) Texas Natural Resource Conservation Commission
(14) vonRoll/WTI
Readers should note that only comments about new information
discussed in this notice will be considered by the Agency. Issues
related solely to the April 19, 1996 proposed rule and other subsequent
notices that are not directly affected by the documents or data
referenced in today's Notice of Data Availability are not open for
further comment.

Glossary of Acronyms

acfm--Actual Cubic Feet per Minute
ACI--Activated Carbon Injection
APCD--Air Pollution Control Device
BIF--Boiler and Industrial Furnace
BTF--Beyond-the-Floor
CAA--Clean Air Act
CEMS--Continuous Emissions Monitoring System
D/F--Dioxins/Furans
ESP--Electrostatic Precipitator
gr/dscf--Grains per Dry Standard Cubic Foot
HAP--Hazardous Air Pollutant
HC--Hydrocarbons
HWC/HWI--Hazardous Waste Combustor/Incinerator
IWS--Ionizing Wet Scrubber
LVM--Low-volatile Metals
LWAK--Lightweight Aggregate Kiln
MACT--Maximum Achievable Control Technology
MTEC--Maximum Theoretical Emission Concentration
NESHAPs--National Emission Standards for HAPs
NODA--Notice of Data Availability
NPRM--Notice of Proposed Rulemaking
NSPS--New Source Performance Standards
PM--Particulate Matter
RCRA--Resource Conservation and Recovery Act
SRE--System Removal Efficiency
SVM--Semi-volatile Metals
TEQ--Toxic Equivalent
g/dscm--Micrograms per Dry Standard Cubic Meter

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TABLE OF CONTENTS

Part One: Background and Overview of Today's Notice

I. Background
II. Overview of Today's Notice

Part Two: Standards For Hazardous Air Pollutants (NESHAPs)

I. Regulation of Area Sources
A. Approach to Regulate Area Sources, as Proposed
B. Positive Area Source Finding for HWCs
C. Title V Permitting Requirements for Area Sources
II. Revisions to Proposed Standards Using the Revised Emissions
Database and Data Analysis Methods
A. Notice of Data Availability on the Revised Emissions Database
B. PM as a Surrogate for Non-Hg Metals
C. Options for Controlling Emissions of Organic HAPs
D. Accounting for Emissions Variability in Establishing Emission
Standards
E. Re-Evaluation of Proposed MACT Standards for Incinerators
F. Re-Evaluation of Proposed MACT Standards for Cement Kilns
G. Re-Evaluation of Proposed MACT Standards for Lightweight
Aggregate Kilns

Part Three: Implementation

I. Compliance Date Considerations
A. Definition of Compliance Date
B. Pre-Certification of Compliance
C. Consequences of Non-compliance
II. Compliance Requirements
A. Compliance with CO and/or HC Emission Standards
B. Startup, Shutdown, and Malfunction Plans
C. Metals Extrapolation and Interpolation Considerations
D. Consideration of Site-Specific Variances for Cement Kilns and
LWAKs
E. Emissions Averaging for Cement Kilns
III. DRE Testing Considerations
A. Options for Ensuring Compliance with a DRE Standard
B. DRE As a MACT Versus RCRA Standard
IV. Notification and Reporting Requirement Considerations
A. Public and Regulatory Notification of Intent to Comply
B. Data Compression Allowances
V. Waste Minimization and Pollution Prevention
A. Overview
B. EPA Proposed Flexible Waste Minimization Incentives
C. Comments Received
D. Comments Requested on Additional Waste Minimization
Incentives
VI. Permit Requirements
A. Coordination of RCRA and CAA Permitting Processes
B. Permit Process Issues
C. Omnibus and RCRA/CAA Testing Coordination

Part Four: Miscellaneous Issues

I. 5000 Btu per Pound Policy for Kiln Products
II. Foundry Sand Thermal Reclamation Units
A. Background
B. Deferral and Variance Options for Consideration
III. Status of Gaseous Fuels Generated from Hazardous Waste
Management Activities
IV. Regulatory Flexibility Analysis

Part One: Background and Overview of Today's Notice

I. Background

On April 19, 1996, EPA proposed revised standards for three source
categories of hazardous waste combustors (i.e., hazardous waste
incinerators and hazardous waste-burning cement kilns and lightweight
aggregate kilns (LWAKs)), 61 FR 17358. After an extension, the comment
period closed on August 19, 1996.
The Agency subsequently published two Notices of Data Availability
(NODA). The first NODA, published on August 23, 1996 (61 FR 43501)
invited comment on information pertaining to a peer review of three
aspects of the proposed rule, additional analyses of fuel oils that
would be used to establish a comparable fuels exclusion, and
information on a synthesis gas process. The comment period on that NODA
closed on September 23, 1996. The second NODA, published on January 7,
1997 (62 FR 960) provided notice and opportunity to comment on an
updated hazardous waste combustor database containing the emissions and
ancillary data that the Agency plans to use to develop the final rule.
The comment period on that NODA closed on February 6, 1997.
EPA's proposal to revise standards for hazardous waste incinerators
and hazardous waste-burning cement kilns and LWAKs is under joint
authority of the Clean Air Act, as amended, (CAA) and the Resource
Conservation and Recovery Act, as amended (RCRA). The proposed emission
standards were developed under the CAA provisions concerning the
maximum level of achievable control over hazardous air pollutants
(HAPs), taking into consideration the cost of achieving the emission
reduction, any non-air quality health and environmental impacts, and
energy requirements. These Maximum Achievable Control Technology (MACT)
standards, also re ferred to as National Emission Standards for
Hazardous Air Pollutants (NESHAPs), were proposed for the following
HAPs: dioxins/furans (D/F), mercury, two semi-volatile metals (lead and
cadmium), four low volatility metals (antimony, arsenic, beryllium, and
chromium), particulate matter, and hydrochloric acid/chlorine gas.
Other toxic organic emissions were addressed by standards for carbon
monoxide (CO) and hydrocarbons (HC).
Because of the joint authorities for this rule, the proposal also
contained an implementation scheme to harmonize the RCRA and CAA
programs to the maximum extent permissible by law. In pursuing a
common-sense approach towards this objective, the proposal sought to
establish a framework that: (1) Provides for combined (or at least
coordinated) CAA and RCRA permitting of these facilities; (2) allows
maximum flexibility for regional, state, and local agencies to
determine which of their resources will be used for permitting,
compliance, and enforcement efforts; and (3) integrates the monitoring,
compliance testing, and record keeping requirements of the CAA and RCRA
so that facilities will be able to avoid two potentially different
regulatory compliance schemes.

II. Overview of Today's Notice

The Agency received a large number of public comments in response
to the proposal. The Agency evaluated the public comments received and
their applicability to the proposed rule. In those instances where
comments provided new information or new insights, the Agency has
reevaluated certain aspects of the proposal based on this new
information. The Agency is issuing this NODA in an effort to inform the
public of: (1) Significant changes the Agency is considering on aspects
of the proposal based on public comments and new information; and (2)
the Agency's own reevaluation (and to some degree narrowing) of MACT
standard-setting approaches based on new data and (at least in part) on
public comments.

Part Two: Standards for Hazardous Air Pollutants (NESHAPs)

I. Regulation of Area Sources

In this section, we solicit comment on making a positive area
source finding to subject hazardous waste combustor area sources to the
same MACT standards that would apply to major sources and on whether,
under such a finding, area sources should be subject to Title V permit
requirements.
A. Approach To Regulate Area Sources, as Proposed
A major source is a source that has the potential to emit
(considering controls) either 10 tons per year of any hazardous air
pollutant or 25 tons of any combination of HAPs. Area sources are any
sources which are not major sources.
The Agency proposed to subject area sources to MACT standards under
authority of CAA section 112(c)(6). See 61 FR at 17365. That section
requires

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the Agency to subject to MACT standards ¹ all sources in
source categories that account for not less than 90 percent of the
aggregate emissions of each enumerated pollutant. ² The
enumerated pollutants emitted by hazardous waste combustors (HWCs)
include mercury (Hg), D/F, and other polycyclic organic HAPs. The
Agency explained at proposal that HWCs were significant emitters of D/F
and Hg, and that much of the human health risk from emissions of HAPs
from HWCs comes from these high priority HAPs, and D/F in particular.
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\1\ For area sources, section 112(c)(6) requires the Agency to
establish either MACT standards under section 112(d)(2), or
generally available control technology (GACT) standards under
section 112(d)(5). Given the similarities between major and area
source HWCs as discussed in subsequent sections of the text, area
sources should be subject to MACT.
\2\ Section 112(c)(6) enumerates the following high-priority
hazardous pollutants for special regulation: alkylated lead
compounds, polycyclic organic matter, hexachlorobenzene, mercury,
polychlorinated biphenyls, and 2,3,7,8-tetrachlorodibenzofurans and
p-dioxin.
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We received many comments pertaining to this part of the proposal,
and we will address those comments in the final rule. The area source
issue is discussed in today's notice because commenters said that
another, more appropriate reading of section 112(c)(6) is that this
authority could be used to apply MACT control to area sources only for
the enumerated HAPs, not the full array of HAPs that the Agency
proposed to regulate (e.g., particulate matter (PM), semivolatile
metals (SVM), low volatile metals (LVM)). Nonetheless, were EPA to
adopt this reading, the Agency continues to believe that area sources
need to be regulated for this full array of HAPs.
In light of issues commenters raised, we solicit comment on an
alternative approach that would subject area sources to all of the MACT
standards for major sources based on the Agency making a positive area
source finding.
B. Positive Area Source Finding For HWCs
Area sources must be regulated by technology-based standards
³ if the area source category is listed pursuant to section
112(c)(3) based on the Agency's finding that these sources
(individually or in the aggregate) present a threat of adverse effects
to human health or the environment. Such a finding is termed a positive
area source finding. The Agency is today soliciting comment on whether
a positive area source finding is appropriate for hazardous waste
incinerators and hazardous waste burning cement kilns and lightweight
aggregate kilns.
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\3\ That is, MACT standards under section 112(d)(2) or GACT
standards under section 112(d)(5).
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A positive area source finding would be based on the risk
assessment performed for the proposed rule and ultimately the final
rule. Even though the sources modeled in support of the proposed rule
may have met the definition of a major source, EPA believes their HAP
emissions, other than HCl, are also representative of area source
emissions. This is because, as discussed below, these example sources
may be able to reduce their HCl emissions to become area sources
without reducing emissions of D/F, Hg, or other metal HAPs that could
pose significant health risk.⁴
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\4\ From a technical perspective related to the nature of common
air pollution control devices, reducing HCl emissions would not
generally reduce emissions of other HAPs.
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Many comments were submitted on the risk assessment methodology
used to support the proposed rule. We are considering these comments in
development of the final rule and are making appropriate changes to the
risk methodology, including modeling additional facilities. These
changes could affect the Agency's findings for both major and area
sources. The Agency is not today reopening the comment period on the
risk assessment.
1. Risks that could be posed by area source incinerators. We showed
at proposal that baseline emissions from incinerators could pose high
end individual lifetime cancer risks from D/F up to 9E-5. See 61 FR at
17389. In addition, although the risk from low volatile metals (i.e.,
As, Be, Cr, and Sb) was not estimated to exceed 4E-6, the example sites
modeled were not representative of the short stacks of many on-site
incinerators. The direct inhalation component of the individual cancer
risk estimates may increase when incinerators with short stacks are
included in the risk assessment supporting the final rule.
2. Risks that could Be posed by area source cement kilns. The
Agency showed at proposal that baseline emissions from cement kilns
could pose high end individual lifetime cancer risks from D/F up to 9E-
5. See 61 FR at 17402. Although several high D/F-emitting cement kilns
have recently reduced their D/F emissions significantly, a revised risk
assessment may well show that cement kilns (both area and major
sources) can pose significant health risk at current emission levels.
3. Risks that could Be posed by area source lightweight aggregate
kilns. Although the Agency did not show high baseline D/F cancer risks
for LWAKs at proposal, the risk assessment assumed extremely low D/F
emissions--0.04 ng TEQ/dscm--based on very limited data from a single
LWAK. However, as discussed below in section II.G, new data from two
additional LWAKs show substantially higher emission levels--up to 4.1
ng TEQ/dscm. At these emission levels, the high end individual lifetime
cancer risk from D/F could exceed 1E-5.
4. Basis for a positive area source finding. In evaluating these
estimated risk levels to determine whether they are sufficient to make
a positive area source finding, the Agency considered other factors
which EPA believes to be relevant in determining how to exercise its
discretion regarding area source determinations for these sources:
a. HWC area sources can pose the same hazard to human health or the
environment as major sources. An area source may have the same emission
rates of HAPs other than hydrogen chloride (HCl, the principal HAP that
causes a HWC to be a major source) as a major source, and thus pose
essentially the same hazard to human health or the environment. In
other words, sources could have HCl emissions low enough to avoid a
major source classification, but have emissions of D/F that could pose
a health risk given that there is no direct correlation between HCl and
D/F emissions.⁵
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\5\ For well-designed and operated combustion systems, D/F
emissions are related primarily to post-combustion particle surface
catalyzed reactions and the temperature of the combustion gas (the
optimum temperature window for formation is 450-750 deg.F),
virtually irrespective of HCl concentrations in the gas.
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In addition, some HWCs that would currently be classified as major
sources because of their HCl emissions may be able to lower their HCl
emissions to become area sources. The Agency projects that all LWAKs
are currently major sources principally because of their HCl emissions,
and that approximately 80 percent of cement kilns are major sources,
again because of HCl. These HWCs may be able to lower their HCl
emissions to otherwise become area sources.⁶
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\6\ Some commercial incinerators may also be able to lower their
allowable HCl emission levels to become area sources. It could be
more problematic for on-site incinerators to lower their emissions
to become area sources because facility-wide HAP emissions must be
considered when making the major/area source determination. For
example, on-site incinerators located at large chemical production
facilities would need to reduce HAP emissions at a large number of
sources.
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Sources have until the compliance date of the MACT standards (i.e.,
three years after publication in the Federal

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Register) to make a major source determination. Many kilns spiked
chlorine in the hazardous waste feed during compliance testing to get
approval to feed chlorine (and emit HCl/Cl2) at levels ostensibly
higher than normal. Given that sources ``have the potential to emit''
at these ostensibly higher than normal emission rates, these emission
rates must be used for the major source determination. See CAA section
112(a)(1), definition of major source. These sources may be able to
operate successfully at lower allowable chlorine feedrates and emission
rates, however. If so, they can elect to retest their units and base
the major/area source determination on potentially lower HCl/Cl2
emission rates.
b. RCRA sections 3004(o)(2) and 3004(q) essentially command
regulation of all HWCs. Under this RCRA mandate, the Agency has
regulated all (i.e., both major and area sources) hazardous waste
incinerators since 1981 (see 46 FR 7678 (Jan. 23, 1981) as amended at
48 FR 14295 (Apr. 1, 1983)) and all hazardous waste burning cement and
lightweight kilns since 1991 (see 56 FR 7134 (Feb. 21, 1991)).
Deferring regulation of HWCs to the CAA would not be appropriate unless
all HWC sources were covered. In addition, although somewhat more than
half of the commercial incinerators appear to be area sources, the
majority of on-site incinerators are likely to be major
sources.⁷ The public expectation is that all HWCs would
continue to be regulated.⁸
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\7\ Only approximately 30 percent of incinerators appear to be
major sources. This estimate is based on only the incinerators'
stack emissions, however. Given that facility-wide emissions of HAPs
are considered when making a major source determination, many on-
site incinerators are likely to be classified as major sources
because they are located at large petrochemical facilities.
\8\ It would be particularly problematic from a RCRA perspective
for commercial incinerators that are area sources to be exempt from
MACT standards.
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c. MACT controls are reasonable and appropriate for both major and
area sources. The emission control equipment (and where applicable,
feedrate control) defined as floor or beyond-the-floor (BTF) control
for each source category is applicable and appropriate to area sources.
There is nothing unique about the types and concentrations of emissions
of HAPs from area sources versus major sources that would make MACT
inappropriate for an area source.
d. Area source HWCs contribute significantly to D/F and Hg
emissions. Both area and major source HWCs contribute significantly to
aggregate emissions of D/F and Hg, two high priority HAPs. See CAA
section 112(c)(6) and proposal discussion at 61 FR at 17366.
For these reasons, the Agency is taking comment on making positive
area source findings for each of the three source categories covered by
the proposal. Again, the effect would be to subject all sources within
these categories to MACT standards, which also would be the effect of
the original proposal.

C. Title V Permitting Requirements for Area Sources

Under Sec. 63.1(c)(2), area sources subject to MACT (or GACT) are
subject to the requirement to obtain a Title V permit unless the
standard for the source category (e.g., Subpart EEE for HWCs) specifies
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. The Agency has determined that if it
makes a positive area source finding and subjects area sources to MACT
standards as discussed above, the Agency would also consider subjecting
area sources immediately to Title V permitting requirements, as
provided by Sec. 63.1(c)(2)(iii). The Agency has determined that area
source compliance with Title V permit requirements would not be
``impracticable, infeasible, or unnecessarily burdensome''. See CAA
section 502(a). As noted above, area sources can be virtually identical
to major sources with respect to size, type of combustor, and
commercial versus on-site status, except that their mass emissions of
HCl are lower. Thus, waiver of Title V permitting would not be
warranted.
In addition, if the Agency were to waive the Title V permit
requirement for area sources, we would be concerned about the confusion
it would likely create for the regulated community and the public if
the air emissions standards for some hazardous waste combustors (even
in the same source category) were addressed in the Title V permitting
process and the air emissions standards for others were addressed in
the RCRA permitting process. Since a source can make modifications to
their emissions levels that could change their major/area source
determination, a source could move from one permitting program to the
other, creating difficulties for the permitting agencies in tracking
sources and for the public in trying to participate in or follow the
permitting process. Therefore, it appears most appropriate from an
implementation standpoint to subject area sources to Title V
permitting. In this way, all HWCs (both major and area sources) would
be subject to the same Title V permitting requirements.

II. Revisions to Proposed Standards Using the Revised Emissions
Database and Data Analysis Methods.

In this section, the Agency discusses comments on the revised
emissions database and the revised standards that would result from
applying an engineering evaluation and data analysis methods to that
revised database. In addition, we discuss several issues that are
generic to the MACT standards for all three source categories: (1)
Consideration of PM as a surrogate for non-Hg metal HAPs; (2) options
for controlling emissions of organic HAPs; and (3) emissions
variability.
A. Notice of Data Availability on the Revised Emissions Database
On January 7, 1997 the Agency published a NODA on an updated
database of emissions and ancillary information. See 62 FR 960. The
Agency updated the database used at proposal to correct errors and
include additional emissions data. The NODA explained that the updated
database would be used to identify MACT standards for the final rule
and to evaluate economic impacts and, for RCRA purposes, risks
associated with the final MACT standards.
The Agency received comments on the revised database from 16
stakeholders representing the cement industry, lightweight aggregate
industry, and on-site and commercial incinerators. The database was
revised again to accommodate the comments received on the database
NODA. The Agency then re-analyzed the database to determine the MACT
floor standards discussed below.
We received several specific comments (i.e., as opposed to generic
and undocumented comments that, for example, the Agency's data are
inconsistent with the commenter's) that were not accompanied with
supporting documentation. Most of these comments pertain to
miscellaneous data on feedstream feedrates and equipment design
information that do not have a significant impact on developing MACT
floor standards under the data analysis methods discussed in today's
NODA. Where there was a significant possibility that the data might
affect the Agency's determinations, references were re-checked to
determine the more accurate number to be used.
The Cement Kiln Recycling Coalition (CKRC) provided an extensive
run-by-run, HAP-by-HAP comparison of the Agency's database with theirs.
While

[[Page 24216]]

potentially useful in some cases, their submission unfortunately did
not distinguish between significant versus insignificant differences;
nor did they verify which data were more accurate for the purposes in
question. Within current time constraints, the Agency has identified
which appear to us to be significant and relevant differences and then
checked these data to determine which appear to be more accurate and
has made necessary changes. The current database, as updated and
revised, is appropriate and sufficient considering the engineering and
data analysis methods discussed below to identify MACT standards. For
example, although there may still remain differences between CKRC's and
the Agency's database regarding electrostatic precipitator (ESP) and
fabric filter design and performance characteristics, those
characteristics are not germane to the engineering and data analysis
methods for determining relevant MACT standards, as discussed below. In
these situations, the Agency has elected not to revise inconsequential
data, particularly where it is not clear which data are more accurate.
Some overall decisions on data quality issues have also been made
for purposes of revising the database. Regarding assigning values to
reported nondetects, we are assuming that nondetected values were
present at one-half the detection limit. We considered assuming
nondetected values were present at the full detection limit, but found
in most cases no significant difference in the MACT data analysis
results. It represents a judgment by the Agency based on its experience
that, for assessing standards and risk, this more conservative approach
increases our confidence that standards and risk are appropriate and
acceptable.
In addition, we are excluding data from sources no longer burning
hazardous waste, as suggested by several commenters on the proposed
rule. Although such data may well be indicative of the capabilities of
control equipment and thus relevant, the resulting database is still
large enough to ensure that potential final MACT standards can be
judged to be achievable (or not as the case may be) without including
these more controversial data. Regarding older emissions data when more
recent data was available for a source, we are considering all data
sets for sources that currently burn hazardous waste. Both recent and
old data are instructive in assessing the capabilities of the control
equipment at these operating facilities.
Finally, we screened out so-called ``normal'' emissions data from
the MACT analyses. Although doing so may appear counterintuitive at
first blush, one must consider that facility compliance will generally
be based on operating limits established during the MACT performance
test (except if compliance is based on a continuous emissions
monitoring system (CEMS)). During these MACT performance tests, sources
will likely operate under the same worst-case conditions as they did
during trial burns and Boiler and Industrial Furnace (BIF) rule
certification of compliance testing. Operating under worst-case
conditions with respect to emissions and operating parameters gives
operators a wide allowable envelope of operating limits needed to
efficiently and economically operate the combustor and yet maintain
compliance. Considering normal emissions data in the MACT analysis
could inappropriately result in the Agency establishing a MACT standard
based on normal emissions and conditions while the source would be
operating under worst-case conditions to demonstrate compliance. Thus,
emissions while complying with operating limits would be
inappropriately constrained to below current normal emission levels,
even for sources equipped with well-designed and operated MACT floor
control.
B. PM as a Surrogate for Non-Hg Metals
The Agency proposed a MACT PM standard as a surrogate for non-D/F
organic HAPs (that are adsorbed onto the PM) and for the metal HAPs not
individually regulated under the proposed metal standards (i.e., Co,
Mn, Ni, and Se). See 61 FR at 17376.
Since proposal, the Agency has reconsidered in the context of this
joint RCRA-CAA rulemaking whether a MACT PM emission standard could
serve as a surrogate for six non-Hg metal HAPs for which the Agency did
propose specific standards--semivolatiles (Cd and Pb) and low volatiles
(As, Be, Cr, and Sb). This issue arises, in part, because the risk
assessment at proposal on the MACT standards estimated that the high-
end individual lifetime cancer risks using 90th percentile metal
emission levels were well below 10^-6 for cement kilns and
LWAKs. For incinerators, the highest estimated cancer risks exceeded
10-6 but were below 10^-5.\9\
---------------------------------------------------------------------------

\9\ Note, however, that the example incinerators modeled for the
risk assessment had relatively tall stacks which may not result in
the higher ground level concentrations (and thus higher direct
inhalation risk) that could result from small incinerators.
---------------------------------------------------------------------------

To evaluate PM as a surrogate for non-Hg metals in the context of
this joint RCRA-CAA rulemaking, questions that must be addressed are:
(1) Would a MACT PM standard control the six non-Hg metals to MACT
emission levels in the special context of hazardous waste combustors;
and (2) would there be significant health risk at MACT emission levels
that would have to be addressed with RCRA controls (based at least in
part on site-specific risk assessments using omnibus authority)?
Because, in the case of hazardous waste combustors, there are
significant levels of metals in the hazardous waste-derived fuel being
burned, the Agency has initially concluded that a MACT PM emission
standard in this particular rule may not adequately control the six
non-Hg metals to the nominal MACT emission levels. The residual risk
that could result from emissions of some of the six non-Hg metals could
be significant ¹⁰, and regulation of these problematic
metals under RCRA would therefore be warranted. From an implementation
standpoint, this result of mixed statutory controls is not desirable.
Although establishing six additional specific limits on the non-Hg
metals eliminates this particular implementation disadvantage, this
would add to the compliance and implementation burdens on facility and
regulator alike. Consequently, it does not currently appear appropriate
to use PM as a surrogate for all six toxic, non-Hg metals.
---------------------------------------------------------------------------

\10\ This is at least partly because a PM control device alone
does not give the same targeted degree of control for individual
metals that a combination of metal feed control plus a PM control
device does.
---------------------------------------------------------------------------

In investigating this issue, however, we determined that antimony
(Sb), one of the four low volatile metals, may not warrant direct
control. That is, the MACT PM standard may serve as an adequate
surrogate for Sb to ensure that it is not emitted at levels that pose a
health risk. ¹¹ We also considered whether beryllium (Be),
another LVM, warranted control given that it is not generally present
in significant concentrations in hazardous waste, and baseline
emissions of Be do not appear to be posing a health hazard. Given that
Be is a toxic carcinogen, however, direct MACT controls should be
provided even if current feedrates (and emission rates) are low.
---------------------------------------------------------------------------

\11\ Sb is a non-carcinogen with relatively low toxicity
compared with the other five non-Hg metals, and would have to be
present in hazardous waste (and emitted PM) at extremely high levels
(perhaps over 1000 times the current levels) to pose a health
hazard. Current data suggest that metals feedrates generally are
either not increasing or increasing at much lower rates.
---------------------------------------------------------------------------

Only a preliminary analysis (see discussion below) was used to
investigate whether some of the

[[Page 24217]]

remaining semivolatile and low volatile metals--Cd, Pb, As, and Cr--may
warrant only indirect control through a PM standard for any or all of
the HWC source categories. We continue to believe that direct standards
are warranted for these four metals (either individually or in
volatility groups). For purposes of public comment, we have identified
MACT standards for these individual metals in case individual standards
are ultimately deemed more appropriate than continuing to group the
metals by relative volatility. However, we remain concerned about the
compliance and implementation complexities that would be introduced.
(See the discussion below of revised SVM and LVM standards for each
source category.)
We solicit further comment on how to ensure appropriate and
effective control of non-Hg metal HAPs while ensuring that the
regulatory scheme and associated compliance elements are implementable
and not unnecessarily burdensome. Some of the pertinent issues are
highlighted below for commenter response.
1. Can PM serve as a surrogate for SVM and LVM? A MACT PM standard
would provide MACT emissions control technology (i.e., the air
pollution control device) for non-Hg metals. This is because stack
emissions of non-Hg metals in combustion gases are controlled by the PM
control device. Thus, MACT control (i.e., the emission control device)
for PM would also be MACT control for non-Hg metals.
However, emissions of non-Hg metals from HWCs are also controlled
by the feedrate of non-Hg metals (for kilns, the feedrate of non-Hg
metals in hazardous waste) in addition to the PM control device. Thus,
a MACT PM standard alone may not result in control of non-Hg metals to
MACT emissions levels because emissions of non-Hg metals will vary at a
given PM level as feedrate varies (i.e., emissions of non-Hg metals
will be a greater percentage of PM emitted as the feedrate rises).
Some commenters have argued that PM is not a good surrogate for
non-Hg metals emissions. When sources (within a source category) are
considered in the aggregate, a poor correlation between PM and non-Hg
metals emissions appears to exist. This is because sources have various
feedrates of the metals and because different types of PM control
devices have different collection efficiencies for these metals.\12\.
\13\ Nonetheless, at a given source with a given non-Hg metal feedrate,
metal emissions will correlate with PM emission levels. Although the
correlation will be different for more volatile versus less volatile
metals, emissions of these metals will increase as PM emissions
increase.
---------------------------------------------------------------------------

\12\ In addition, metal collection efficiency of the PM control
device varies at different metal feedrates.
\13\ See, for example, comments submitted by Chemical
Manufacturers Association, RCRA Docket # F-96-RCSP-FFFFF comment #
RCSP-00128.
---------------------------------------------------------------------------

In summary, although there is a correlation between PM and non-Hg
metal emissions on a facility-specific basis, and the MACT PM standard
likely would ensure use of MACT emission control device for these
metals, it may not ensure attainment of MACT emission levels of these
metals. Given the potential for HWCs to emit high levels of some of
these metals, metal-specific emission controls--MACT standards--are
warranted either individually or in volatility groups.
2. Which non-Hg metals warrant specific control by establishing
MACT emission standards? As an alternative to establishing MACT
standards for SVM and LVM as proposed, we are re-evaluating which non-
Hg metals warrant special control and whether to establish individual
MACT emission standards for them. ¹⁴ As discussed above, our
preliminary analysis indicates that standards may not be warranted for
Sb. We are continuing to investigate whether any of the remaining
metals--As, Be, Cd, Cr, and Pb--may not warrant direct emission
standards but may warrant only indirect controls via the PM standard.
Further, we are investigating how the metal standards should be
structured: (1) MACT standards for individual metals; or (2) MACT
standards for volatility groupings (SVM and LVM) if we determine, as
currently contemplated, that direct standards for all five remaining
metals are warranted (i.e., as proposed).
---------------------------------------------------------------------------

\14\ Other metal HAPs (other than Hg and the six toxic metals
covered at proposal) would be controlled indirectly by the PM
standard and any individual or volatility group metal standards.
This is essentially unchanged from the proposal.
---------------------------------------------------------------------------

For cement kilns and LWAKs, we examined a comparison of potentially
allowable emission levels for non-Hg metals under the BIF rule and
actual allowable (i.e., levels emitted during Certificate of Compliance
(CoC) testing) emission levels. (Note that the actual allowable levels
are generally much higher than normal emission levels because sources
spiked metals during CoC testing.) A wide margin exists--generally an
order of magnitude or greater--between BIF potentially allowable
emission levels and CoC allowable emission levels. This means that: (1)
Cement kilns and LWAKs are not emitting these metals at levels posing a
risk using BIF risk assessment procedures; and (2) cement kilns and
LWAKs are feeding these metals at rates well below those that would be
allowed under BIF risk-based limits and, thus, indirect PM control
under MACT may similarly keep feedrates (and emission rates) of these
metals low.
We also examined data on the percentage of emitted particulate
matter that each non-Hg metal would have to comprise to pose a health
risk, assuming BIF risk assessment procedures were applied. Under this
analysis, Pb and Sb would have to comprise from 10-100 percent of
emitted PM to pose a health risk. Data suggest that these percentages
are not approached in today's operations by a wide margin.
These preliminary analyses were performed assuming BIF risk
assessment procedures. Thus, our evaluation may not be representative
of results that will be forthcoming shortly using updated, more
detailed procedures for evaluating risks under the final MACT
standards. For example, the risk assessment for this rule considers
indirect exposure (i.e., ingestion and food-chain uptake) while BIF
procedures consider only direct inhalation. On the other hand, BIF
direct inhalation exposure assessment procedures are more conservative
(i.e., result in a higher estimate of risk) than those that will be
used for the final MACT standards because the Agency has revised those
procedures in part to consider more realistic exposure scenarios.
Nonetheless, the analyses discussed above are viewed as suggestive that
regulation of each and every semivolatile and low volatile metal as
proposed may not be warranted.
We could not perform similar preliminary analyses for incinerators
because we do not have dispersion coefficients readily available that
would be representative of the short stacks used by many on-site
incinerators. However, a review of the emissions database indicates
that, as expected, some incinerators--both commercial and on-site
incinerators--emit much higher levels of these metals than cement kilns
or LWAKs. Nonetheless, we may find (as may be the case for cement kilns
and LWAKs) that Sb may not warrant a direct metal-specific standard for
incinerators as well, either as part of the LVM group or an individual
standard.

[[Page 24218]]

C. Options for Controlling Emissions of Organic HAPs
Based on evaluation of the revised emissions database, the Agency
is soliciting comment on options to control emissions of organic HAPs
by: (1) Establishing MACT standards for carbon monoxide (CO) and/or HC
emissions as surrogate indicators of good combustion conditions;
¹⁵ and (2) ensuring that sources achieve 99.99 percent
destruction and removal efficiency (DRE).¹⁶ These options
are presented in Part Three: Implementation, Sections II and III,
because the DRE issue has implementation implications, and the CO/HC
issue relates to the DRE issue.
---------------------------------------------------------------------------

\15\ The Agency proposed to establish MACT standards for both CO
and HC, but solicited comment on whether a standard based on one
surrogate or the other may be sufficient. See 61 FR at 17376.
\16\ The Agency proposed to retain DRE as a RCRA standard
because of concerns that it would be difficult to self-implement
under MACT implementation procedures. See 61 FR at 17447. The Agency
is reconsidering this issue and solicits comment on alternative
approaches to ensure compliance with the DRE standard, including
incorporating DRE as a MACT standard.
---------------------------------------------------------------------------

D. Accounting for Emissions Variability in Establishing Emission
Standards
At proposal, the Agency used a statistical approach to identify an
emission level that MACT floor control could achieve routinely
considering that the emissions database was comprised of ``short-term''
test data. See 61 FR at 17366. To identify an appropriate standard, a
computed variability factor considering within-test condition emissions
variability was added to the log-mean of the highest test condition
average for any source using floor control. The log-mean of the runs
for the standard-setting test condition is the ``design level'--the
emission level the source would be designed to meet to ensure emissions
were less than the standard 99 percent of the time, assuming a source
had average within-test condition emissions variability (average based
on all sources using floor control).
We are concerned that this computed variability factor approach may
be inappropriate in this particular rulemaking.¹⁷ For
example, this computed variability factor led to illogical results for
the PM standards for incinerators and LWAKs. In the case of PM, the
calculated standard using the computed variability factor is 50 percent
higher than the current legally-mandated RCRA PM limit for
incinerators. For LWAKs, using the variability factor results in a PM
standard of approximately 0.04 gr/dscf (corresponding to a design level
of 0.022 gr/dscf) nearly twice as high as any PM emission value in the
entire LWAK database. Further, given that floor control would be a
fabric filter, our engineering evaluation ¹⁸ (and the LWAK
database itself) indicates that a fabric filter can readily achieve
levels of 0.022 or below, not the calculated 0.04.
---------------------------------------------------------------------------

\17\ See, for example, proposed rule (61 FR at 17367).
\18\ See USEPA, ``Draft Technical Support Document for HWC MACT
Standards (NODA), Volume I: MACT Evaluations Based on Revised
Database'', April 1997.
---------------------------------------------------------------------------

These inappropriate and illogical results may flow from either the
variability factor itself or the test condition average identified as
the standard-setting test condition (to which the variability factor is
added). For example, the variability factor itself (which considers
within-test conditions emissions variability) could be inappropriately
high if there are outlier runs within test conditions that are not
screened out. Although runs in many test conditions appear to be
outliers (and analytical tests may show them to be outliers) it can be
difficult to justify screening them out unless there is a specific
technical explanation (e.g., unique design or operation feature or
inadequacy) that can be identified. Unfortunately, this information is
often not available for many potential outlier data.
As noted, identifying the standard-setting test condition
inappropriately could be a factor. We have very limited information on
the design, operation, and maintenance characteristics of the emission
control devices and combustors. Accordingly, we have had to define MACT
floor control very generically (e.g., ESP or fabric filter), as
discussed below, without attempting to specify design, operation, and
maintenance characteristics.
Given these concerns and the statute's direction to establish the
maximum but achievable floor standard, we request comment on an
alternative approach to account for emissions variability. This
alternative has two elements. First, when a large data set from sources
using floor control ¹⁹ exists, the range of emission levels
from those sources should adequately reflect emissions variability.
That is, a standard established as the highest test condition average
for sources using floor control represents an emission level that the
control technology is capable of achieving, considering normal
variability in combustor operations, emission control device
operations, and test methods. Where these data show that many sources
using floor control can achieve well below the standard, this
demonstrates that additional emissions variability considerations are
not warranted. Source(s) with emission levels close to the standard
should be able to determine how to emit at levels below the standard
based on the specific design, operation, and maintenance information
available to them, especially since many other sources with the same
basic equipment are doing so.²⁰ Second, where only a small
set of data from sources using floor control exists, the range of
emission levels from these sources may be less likely to reflect
emissions variability. In this case, consideration of an additional
variability factor (to be added to the highest test condition average
for a MACT-control facility) may be appropriate.
---------------------------------------------------------------------------

\19\ Or, in the case of LWAKs, where the data set is essentially
complete (i.e., where we have data from all or most of the sources
in the source category).
\20\ No patterns in process design or operation in the
information we have explain why some sources thought to be using
floor control had significantly higher emissions than other sources
thought to be using floor control. Where floor control is based on
an emission control device, these high emitters are likely not in
fact using floor controls--considering the suite of design,
operation, and maintenance factors that affect performance of the
control equipment but on which the Agency has no data. Where floor
control is based on finite control such as combustion gas
temperature or feedrate control, the high emitters may be
experiencing emissions during the compliance test on the high end of
the range of emissions variability.
---------------------------------------------------------------------------

The impact of this alternative approach has been examined. We do
not have a large data set in the expanded universe for two standards:
D/F standards for incinerators equipped with waste heat recovery
boilers and D/F standards for LWAKs. In each case, we have data from
only three sources, and consequently floor control is based on the
suite of controls used by all three sources.²¹ If the data
set were large, we would identify the floor level as the test condition
with the highest run average. But, given the small data set, it is
reasonable from an engineering vantage point to identify the standard
as the highest single run for the highest test condition (when the unit
was properly operated).
---------------------------------------------------------------------------

\21\ When data are available from fewer than 30 sources, MACT
floor is defined as the median emission limitation achieved by the
best five performing sources. Thus, the best performing three
sources (representing the median (and better performers)) define
MACT in this case.
---------------------------------------------------------------------------

We discuss below engineering and data analysis methods and the
resulting standards for each HAP and source category where a computed
variability factor is not used to establish emission standards.

[[Page 24219]]

Finally, we are using an engineering evaluation to identify a
design level for each standard for purposes of estimating economic
impacts and, for RCRA purposes, the risk associated with the design
level for a given MACT standard. The design level is the emission level
to which the control equipment must be designed to ensure compliance
with the standard. For the RCRA risk analysis of the final MACT
standards, we will analyze risks under the more realistic assumption
that a source is emitting at the design level on average, rather than
right at the standard all of the time.
Based on discussions with several air pollution control device
vendors and facility operators, a design level of 70 percent of the
standard is deemed appropriate because it is within the range of
reasonable values that may be encountered--50 percent to 90 percent. To
the extent that industry engineering experience suggest that a
different design level assumption would be more typical and reasonable,
we invite commenters to provide that information.
We also considered whether the design level as a percentage of the
standard (i.e., design factor) should vary depending on whether the
control is finite (e.g., temperature control or feedrate control)
versus an emission control device that is affected by various
parameters, or the type of emission control device (e.g., metals
controlled by feedrate and an ESP or fabric filter). However, we do not
have enough information to establish such tailored and case-specific
design factors. If commenters supply sufficient information, we will
consider using this approach.
As noted, we will use the design factor to estimate costs of
retrofitting for all sources with emissions exceeding the standard. For
these sources, we will estimate the costs of upgrading emission control
equipment to meet the design level. For sources using floor control
(i.e., sources in the expanded universe) that have emissions greater
than the design level, however, we will not attribute retrofit costs
for compliance. Given that these sources are using floor control and
that, as discussed above, the large data set of sources using floor
control and meeting the floor standard amply accounts for emissions
variability, we will presume that these relatively high emissions for
such floor-controlled sources represent the high end of the range of
emissions variability. In other words, when these sources retest
emissions under the same conditions, their emissions should meet the
standard.
E. Re-Evaluation of Proposed MACT Standards for Incinerators
We discuss in this section the basis for the revised standards for
incinerators that result from applying engineering and data analysis to
the revised emissions database. We also discuss refinements to
analytical approaches used in the proposal for identifying floor
controls and levels.²² A comparison of the originally
proposed and potentially revised standards for existing and new sources
is presented in the table below:
---------------------------------------------------------------------------

\22\ Additional details of the engineering and data analysis
evaluations performed on the revised emissions database can be found
in the Agency's background document: USEPA, ``Draft Technical
Support Document for HWC MACT Standards (NODA), Volume I: MACT
Evaluations Based on Revised Database'', April 1997.

Table II.E.--Revised Standards for Existing and New Incinerators \1\
----------------------------------------------------------------------------------------------------------------
Existing sources New sources
-------------------------------------------------------
HAP or HAP surrogate Proposed Revised Proposed Revised
standard standard standard standard
----------------------------------------------------------------------------------------------------------------
D/F (ng TEQ/dscm)....................................... 0.20 0.20 0.20 0.20
Hg (g/dscm).................................... 50 40 50 40
PM (gr/dscf)............................................ 0.030 0.015 0.030 0.015
HCl/Cl2 (ppmv).......................................... 280 75 67 75
CO (ppmv)............................................... 100 100 100 100
HC (ppmv)............................................... 12 10 12 10
SVM (g/dscm)................................... 270 100 62 100
LVM (g/dscm)................................... 210 55 60 55
----------------------------------------------------------------------------------------------------------------
\1\ All emission levels are corrected to 7% O2.

1. Subcategorization considerations. Since proposal, the Agency has
refined potential options for subdividing the incinerator source
category to determine if subdivided standards would be appropriate: (1)
Small \23\ versus large sources; (2) commercial versus on-site sources;
and (3) small on-site sources versus large on-site and commercial
sources. In large part, commenters believed that small, on-site
incinerators should have less stringent standards to reduce costs of
compliance. However, given that our analysis shows that the revised
standards for the small on-site sources would either remain the same or
be more stringent under these options, we continue to believe that
subdividing would be inappropriate.\24\
---------------------------------------------------------------------------

\23\ An analysis of gas flowrates in actual cubic feet per
minute (ACFM) indicated that a maximum flowrate of 20,000 acfm would
be within the range of values that could be selected to designate
small versus medium incinerators. We performed a similar analysis at
proposal and selected a flowrate of 23,127 to designate small
incinerators. See 61 FR at 17372.
\24\ The Agency requested at proposal comments on other means of
reducing costs to small, on-site incinerators (e.g., waiving
requirements for CEMS). We will consider all submitted comments on
options to reduce costs on these units in the final rule.
---------------------------------------------------------------------------

We also received comments from the US Department of Energy (DOE)
suggesting that DOE's mixed waste \25\ incinerators had several unique
features (discussed below) that would warrant subcategorization.\26\ We
are investigating whether DOE's incinerators pose unique implementation
and compliance problems and therefore are considering several options
for the final rule: (1) no subcategorization; (2) subcategorization for
mixed waste incinerators; and (3) deferral of MACT regulation for mixed
waste incinerators (with RCRA rules continuing to apply).
---------------------------------------------------------------------------

\25\ Mixture of low level radioactive waste and hazardous waste.
\26\ See summary of DOE/EPA meeting at RCRA Docket # F-96-RCSP-
FFFFF item # S00270.
---------------------------------------------------------------------------

Under the No Subcategorization Option, we would find that the MACT
controls and emission standards applicable to other incinerators are
appropriate for DOE's mixed waste incinerators. Under this option we
could still define special compliance requirements that account for any
unique features of mixed waste incinerators.

[[Page 24220]]

Under the Subcategorization Option, we would find that because of
unique design or operating features, the MACT controls or emission
standards identified for other incinerators are not appropriate for
mixed waste incinerators. MACT standards unique to these incinerators
would be developed, and special compliance requirements could be
defined.
Under the Deferral Option, we would determine that we do not have
the resources to make an appropriate MACT determination on mixed waste
incinerators in time to meet the schedule for the HWC rulemaking (i.e.,
the Phase I rule establishing MACT standards for incinerators, cement
kilns, and LWAKs). Regulation of mixed waste incinerators would be
deferred to the Phase II rule where the Agency will establish MACT
standards for hazardous waste burning boilers, halogen acid furnaces,
and sulfur recovery furnaces. The RCRA rules which now apply would
continue to do so.
DOE suggests that its mixed waste incinerators have several unique
features that would require subcategorization and special compliance
standards:
Each of DOE's four conventional incinerators meet the
Agency's definition of small incinerators (i.e., <20,000 acfm="" gas="" flow="" rate),="" and="" one="" is="" batch-operated="" only="" once="" or="" twice="" a="" year="" with="" a="" gas="" flow="" rate="" of="" 3,000="" acfm.=""> Several mixed waste thermal treatment units meeting the
Agency's definition of an incinerator are small vitrification devices
designed to process metal bearing wastes and feed wastes with extremely
low organic content.
Given that most of the mixed waste incinerators are very
small units, a mass-based emission limit would be more appropriate than
a concentration-based emission limit.
Approximately 95 percent of the mixed waste that is
incinerated is ``legacy waste'' generated during production of nuclear
weapons from 1943 until 1989 and may contain high levels of mercury
that cannot be lowered by source reduction.
Control of mercury emissions using activated carbon
injection (ACI) would be problematic because the spent carbon would be
a mixed waste, and if it contained more than 260 ppm of mercury,
mercury retorting would be required under the Agency's land disposal
restrictions even though there are no retorters in the country that
manage mixed waste (and so a variance would have to be obtained under
Sec. 268.44).
Given that CEMS are not yet demonstrated for multi-metals
(and a CEMS requirement for mercury alone is also problematic for the
final Phase I rule), compliance with MACT metal emission limits would
be based on feedrate limits for metals in feedstreams, a potentially
unworkable approach for mixed waste since sampling and analysis of
radioactive feedstreams raises serious human health concerns.
DOE has negotiated plans and agreements with States under
Site Cleanup Agreements mandated by RCRA section 3021(b) and CERCLA
section 120(e), and such plans and agreements would probably require
renegotiation (and delay) to comply with the proposed MACT standards.
The Agency is continuing to investigate these issues and will make
a determination regarding the appropriate regulatory option in the
final rule.
2. Dioxins and Furans (D/F) a. MACT floor for existing sources. We
proposed a MACT floor standard of ``0.20 ng TEQ/dscm or gas temperature
at the PM control device 400 deg.F'' based on floor control
of temperature at the PM control device. During subsequent analysis of
the revised database, we noticed again that incinerators equipped with
waste heat boilers have significantly higher D/F emissions than other
incinerators. This is likely because the heat recovery boiler precludes
rapid temperature quench of combustion gases to a temperature of
400 deg.F (usually with a wet scrubber), which would be
floor control for non-waste heat boilers. Floor control for waste heat
boilers would be rapid quench of combustion gases at the exit of the
boiler to a temperature of 400 deg.F.
Based on the revised database, the floor standard for waste heat
boilers would be ``0.20, or 12 ng TEQ/dscm and a temperature of
400 deg.F at the PM control device.'' Given that the waste
heat boiler expanded universe (i.e., the entire database) is comprised
of only three sources, the highest single run for the test condition
with the highest run average is a reasonable floor level. (Note that if
this were a large data set, we would define the floor level simply as
the highest test condition average.) This floor level is 50 percent
higher than the highest test condition average, and thus appears to be
a level that waste heat boilers should be able to meet routinely using
floor control.
The floor standard for non-waste heat boilers would be ``0.20, or
0.40 ng TEQ/dscm and a temperature of 400 deg.F at the PM
control device.'' This standard is based on arraying emission levels
for sources using floor control and screening out four test conditions
with anomalously high emissions. Three of these test conditions were
from sources for which we had other test conditions with emissions
averages well below 0.40 ng TEQ.
We did not originally propose separate standards for waste heat
boilers because the floor standard at proposal was ``0.20 ng TEQ/dscm
or temperature at the PM control device of <400 deg.f.''="" waste="" heat="" boilers="" could="" meet="" that="" standard,="" and="" moreover,="" we="" proposed="" a="" btf="" standard="" of="" 0.20="" ng="" teq/dscm="" for="" all="" incinerators="" (a="" preference="" we="" do="" not="" depart="" from="" in="" today's="" notice).="" today,="" however,="" we="" are="" presenting="" the="" option="" of="" stating="" the="" standard="" in="" the="" form="" of="" a="" teq="" level="" combined="" with="" a="" maximum="" temperature="" at="" the="" pm="" control="" device.="" this="" form="" of="" the="" standard="" is="" consistent="" with="" the="" revised="" data,="" and="" would="" result="" in="" somewhat="" lower="" emissions.="" this="" is="" because,="" without="" the="" teq="" limit,="" some="" sources="" could="" exceed="" that="" teq="" level="" at="" the="" specified="" temperature.="" b.="" btf="" considerations="" for="" existing="" sources.="" incinerators="" can="" be="" equipped="" with="" aci="" at="" temperatures="">400 deg.F to achieve D/F
levels below 0.20 ng TEQ/dscm. Given the limited application of the
technology to control D/F emissions from hazardous waste incinerators
and given that control efficiency is likely to decrease at D/F emission
levels below 0.20, a BTF standard of 0.20 ng TEQ/dscm would continue to
be appropriate. See proposal for extended discussion, 61 FR at 17382.
Another option arising from the refinement of our original analysis
is to establish a BTF standard for waste heat boilers at ``0.20, or
0.40 ng TEQ/dscm and a temperature of 400 deg.F at the PM
control device'', and to remain at the floor standard for non-waste
heat boilers. These standards would ensure that most, but not all,
sources would have emissions 0.20 ng TEQ/dscm. Given that
only a few sources would need to take additional measures to get their
emissions below 0.20, however, it would be appropriate to establish a
0.20 BTF standard, assuming this level remains appropriate after
considering statutory factors for establishing standards more stringent
than the floor.
c. MACT floor for new sources. At proposal, we identified the same
floor control for new sources as for existing sources: wet scrubbing
and 400 deg.F at the PM device. This is because the sources
with the lowest emissions used this control. In re-evaluating the
database for this NODA, however, an engineering evaluation may be more
appropriate to identify ACI as floor control because one source (i.e.,
the single best controlled source) uses it. Even though most sources
using rapid quench by wet scrubbing can achieve D/F levels less than
0.20 TEQ, some

[[Page 24221]]

sources using wet scrubbing have higher D/F levels. ACI operated at 400
deg.F or lower can universally achieve D/F levels of 0.20 ng TEQ/dscm
or less and is thus the better performing technology. (Note that waste
heat boilers cannot use rapid quench of combustion gases but can use
ACI.)
Although the source equipped with ACI (Waste Technologies
Industries) is achieving D/F levels of 0.07 ng TEQ/dscm, we believe
that it is appropriate to conclude that ACI can routinely achieve a
standard of 0.20 ng TEQ/dscm given the limited application to date of
the technology for hazardous waste incinerators and the uncertainties
about how much ACI control efficiency is reduced at extremely low D/F
emission concentrations. However, we specifically invite comment on the
potential levels that can be reached with ACI, and on industry-wide
achievability of 0.07 ng TEQ/dscm as the floor for new sources.
d. BTF considerations for new sources. At proposal, BTF for new
sources was based on performance of ACI given that floor control was
based on performance of rapid quench. Under today's analysis, MACT
floor for new sources would be based on ACI. Although carbon beds would
be able to achieve lower emissions, they are not thought to be cost-
effective (particularly if the floor for new sources was well below
0.20 ng TEQ/dscm), and a BTF standard would likely not be appropriate.
3. Mercury (Hg). a. MACT floor for existing sources. At proposal,
the Agency identified floor control as either (1) feedrate control of
Hg at an maximum theoretical emission concentration (MTEC) not to
exceed 19 g/dscm, or (2) wet scrubbing with feedrate control
of Hg at an MTEC not to exceed 51 g/dscm. We proposed a floor
standard of 130 g/dscm.
Mercury emissions from incinerators are currently controlled by
limiting the feedrate of Hg combined with some removal by air pollution
control systems (APCS). There are two APCS techniques currently used by
hazardous waste incinerators (HWIs) to control Hg: wet scrubbers and
ACI. Although primarily intended for acid gas control, nearly all
incinerators employ wet scrubbers that capture the soluble forms of Hg
species (e.g., mercury salts). ACI is used by one incinerator for
control of Hg (and D/Fs). The Agency also has data from one additional
facility using ACI; however, these data were generated during a
demonstration testing program.
Review of the updated Hg data in the revised database shows that
feedrates vary substantially. Generally the higher feedrates are the
result of Hg spiking. We re-evaluated the revised database for today's
notice using a data analysis method similar to that used at proposal to
determine floor levels: (1) Rank Hg emissions from lowest to highest;
(2) define as floor control the air pollution control device (APCD) and
associated highest Hg MTEC for the 6 percent of sources with the lowest
emissions; and (3) define as the floor standard the highest test
condition average emissions of any test condition operated at or below
the Floor MTEC. Using the revised database, MACT control would be
defined as wet scrubbing with a MTEC of 50 g/dscm, and the
revised floor standard would be 40 g/dscm. Nearly 60 percent
of HWIs for which we have data are achieving this level.
b. BTF considerations for existing sources. The Agency originally
considered flue gas temperature reduction to 400 deg.F or less
followed by ACI as the BTF option for improved Hg control. As discussed
at proposal, EPA believes that ACI incinerator applications can achieve
Hg emission reductions greater than 90 percent. In the Notice of
Proposed Rulemaking (NPRM), the Agency proposed a BTF standard of 50
g/dscm.
As mentioned above for existing sources, the Agency has in its
database Hg data from one facility (with two test conditions) currently
employing ACI as a permanent application. Both test conditions achieved
Hg removal efficiencies between 97 and 98 percent at varying Hg
feedrates. The Agency also has data from a second facility generated
during a demonstration test that show about a 98 percent effectiveness
at capturing Hg though at one of the highest feedrates in the database.
These data, in addition to ACI applications on full-scale municipal
waste combustors and medical waste incinerators,²⁷ support
the Agency's assumption that ACI systems can readily achieve capture
efficiencies of 90 percent or more on incinerators.
---------------------------------------------------------------------------

\27\ USEPA, Section 5 of ``Draft Technical Support Document For
HWC MACT Standards, Volume III: Selection of Proposed MACT Standards
and Technologies,'' February 1996.
---------------------------------------------------------------------------

In light of the revised database, EPA can initially identify 4
g/dscm as the potential BTF standard based on ACI and flue gas
temperature reduction to 400 deg.F or less. This is based on a source
achieving the floor level of 40 g/dscm and then applying ACI
with a 90 percent removal efficiency. However, a BTF level of 4
g/dscm will likely raise significant cost-effectiveness
considerations. Given that the floor level discussed today would be
substantially lower than the proposed floor, a BTF standard of 4
g/dscm would be less cost-effective than the BTF levels of 30
g/dscm and 5 g/dscm analyzed at proposal.
c. MACT floor for new sources. At proposal, the floor control for
new sources was similar as for existing sources: wet scrubbing with
feedrate control of Hg at an MTEC not to exceed 51 g/dscm. We
proposed a floor standard of 115 g/dscm.
As discussed for existing sources, both wet scrubbing and ACI are
used for Hg control. The single best performing source for Hg control
in our database, measured by lowest emissions, is a wet scrubber with
Hg feedrate, expressed as a MTEC, of 50 g/dscm. Since MACT for
new HWIs is identical to MACT for existing sources, analysis of
emissions using these or better controls would result in a floor level
for new HWIs of 40 g/dscm.
The Agency also considered a MACT floor based on ACI, a technology
more effective at Hg control than typical wet scrubbing applications.
The three test conditions in the database indicate that ACI was
effective in removing over 97 percent of Hg. However, the Hg feedrate
during the single best ACI test condition was higher than the feedrate
associated with the single best performing wet scrubber. In fact, Hg
feedrates during the ACI test conditions ranged from 5 to 300 times
greater than the wet scrubber MTEC level. To determine an emissions
level that ACI could routinely achieve, we applied a capture efficiency
of 90 percent to a Hg MTEC of 500 g/dscm, a typical feedrate
identified by a MTEC breakpoint analysis. Thus, using the revised
database, the floor level for the ACI evaluation would be 50
g/dscm which is slightly higher than the wet scrubber floor
analysis. The floor for new sources based on the wet scrubber
evaluation appears to be more appropriate because the floor level for
new sources should be at least as stringent as for existing sources.
d. BTF considerations for new sources. At proposal, BTF for new
sources was based on ACI. Similar to existing sources, the Agency re-
considered the use of ACI as the BTF technology. We identified a level
of 4 g/dscm as a potential BTF standard for new sources based
on ACI and flue gas temperature reduction to 400 deg.F or less. As
discussed for existing sources, this BTF level based on ACI will likely
raise significant cost-effectiveness considerations.
4. Particulate Matter (PM). a. MACT floor for existing sources. At
proposal, EPA defined floor control based on either (1) a fabric filter
with an air-to-

[[Page 24222]]

cloth ratio of 10 acfm/ft², or (2) a venturi scrubber used
with an ionizing wet scrubber (IWS). The resulting floor level, which
included a statistically-derived variability factor, was 0.107 gr/dscf.
Since this level is higher than the current federal standard of 0.08
gr/dscf, the Agency identified the floor level as 0.08 gr/dscf.
Today, in light of the revised database, EPA is taking comment on
two refined engineering and data analysis methods to identify the PM
MACT floor for HWIs. The evaluation technique and results from both
analyses are presented below.
For the first (and possibly EPA's preferred) data method, EPA would
use the following steps to identify the PM floor level: (1) Identify
all PM control equipment currently in use within the HWI source
category, regardless of measured performance; (2) identify as MACT
control those PM APCD applications used by at least 6 percent of
sources that could be expected to routinely and consistently achieve
superior PM performance relative to all control strategies considered;
and (3) identify an emissions level that well-designed, operated and
maintained MACT controls can readily achieve based on generally-
accepted technical and engineering information.
Using this approach, MACT controls would be fabric filter, IWS, and
ESP. Based on the revised database, EPA's evaluation of the MACT floor
performance level readily achievable by a well designed, operated and
maintained MACT control device (fabric filter, IWS, ESP) is 0.015 gr/
dscf. Note that even though the PM MACT floor is based on fabric
filter, IWS and ESP APCDs, a source is not required to employ MACT
floor control but rather only achieve the standard.
Approximately 75 percent of sources employing MACT (measured by
available test condition data) currently are achieving 0.015 gr/dscf.
An evaluation of the remaining PM data exceeding 0.015 gr/dscf from
sources ostensibly employing MACT indicate that 20 to 40 percent of
these data may be inappropriate for inclusion (e.g., an incinerator
with multiple test conditions well below and a few above 0.015 gr/
dscf). Generally, over 50 percent of HWIs, regardless of the PM control
currently employed, are currently achieving a 0.015 gr/dscf level.
The second refined data evaluation method EPA is considering for PM
Floor analysis is similar to the standard-setting process applied at
proposal. This evaluation is a four-step process: (1) Rank all PM
emissions data and identify the MACT floor controls used by the best
performing 6 percent of sources; (2) develop the expanded universe to
include all sources employing MACT control, without further
characterizing MACT control (e.g., air-to-cloth ratio of the fabric
filter, specific collection area for an ESP) as done in the proposal
because of the absence of reliable detailed design, operating, and
maintenance information in the database; (3) for each PM test
condition, evaluate the corresponding SVM system removal efficiency
(SRE) and screen out sources that have relatively poor SREs (i.e.,
outliers above a breakpoint in the data array), which are indicators of
poor design, operation, and maintenance characteristics of the MACT
controls at the source; and (4) identify the MACT floor equal to the
highest test condition average of all test conditions in the PM
expanded universe.
Using this alternative evaluation approach as applied to the
revised database, MACT would be based on any of the following PM
controls: (1) Fabric filter, (2) IWS, (3) ESP, or (4) venturi scrubber
burning liquid low ash wastes. The resultant MACT floor would be 0.029
gr/dscf. Over 70 percent of HWIs, regardless of the PM control
equipment employed, are currently achieving this level. A potential
drawback of using this second alternative evaluation technique is that
nearly 75 percent of the available incinerator PM data do not have
corresponding SVM data such that a SRE could be calculated. This
impacts our ability to identify and screen out poorer performing MACT
APCDs from the expanded universe, a critical step in evaluating an
appropriate performance level achievable by MACT control. As a result,
this evaluation technique may not be appropriately identifying a PM
floor level representative of MACT. For these reasons, the first data
method evaluation appears to be more reliable and sound for the
Agency's revised database. The Agency requests comments on the both
data analysis methods presented.
In the NPRM, the Agency proposed that sources maintain continuous
compliance with the PM standard through the use of a PM CEMS. A
decision whether to require incinerators to install a PM CEMS will be
made at the completion of an on-going demonstration testing program to
determine if at least one PM CEMS can meet the proposed performance
specifications. Since the floor standards discussed above were based on
manual test method data, the Agency will re-evaluate at the completion
of the CEMS testing program whether these PM floor standards would be
appropriate in the event that the final rulemaking requires continuous
compliance with a PM CEMS. The Agency will notice the results and
conclusions of the demonstration test program in the docket for the HWC
rule.
b. BTF considerations for existing sources. In the NPRM, the Agency
proposed a BTF level of 0.030 gr/dscf and solicited comment on an
alternative BTF level of 0.015 gr/dscf based on improved PM control.
Based on the revised database, we can evaluate a reduced PM
emissions level lower than 0.015 gr/dscf as the BTF standard (in
conjunction with corresponding BTF reductions in SVMs and LVMs) for
existing HWIs. This would require an improved PM collection technology
such as the use of more expensive bag material for fabric filters or
increased plate area or power input to an ESP. Given that the
alternative floor level analyses presented today would be substantially
lower than the proposed floor and BTF levels, significant cost-
effectiveness considerations come into play and suggest that a BTF
standard may not ultimately prove to be appropriate.
c. MACT floor for new sources. At proposal, the Agency defined
floor control as a fabric filter with an air-to-cloth ratio of less
than 3.8 acfm/ft². The proposed floor level was 0.039 gr/
dscf.
Based upon our evaluation of the revised database, the floor
control and emission level discussed above for existing sources would
also appear to be appropriate for new sources. If this eventuates, then
MACT floor control would be a well-designed and properly operated PM
control device (e.g., fabric filter, IWS, or ESP), and the MACT floor
for new HWIs would be around 0.015 gr/dscf.
d. BTF considerations for new sources. At proposal, EPA proposed
the same BTF standard of 0.030 gr/dscf (based on improved PM control)
as that proposed for existing sources.
Today, given the cost-effectiveness considerations discussed above
for existing sources, the Agency is inclined to think that a BTF
standard beyond a PM floor level of 0.015 gr/dscf (and corresponding
BTF reductions for SVMs and LVMs) would not ultimately prove to be
acceptable.
5. Semivolatile metals (SVM) (cadmium and lead) a. MACT floor for
existing sources. At proposal, EPA defined floor control as either (1)
a venturi scrubber with a MTEC not to exceed 170 g/dscm, (2) a
combination of an ESP and wet scrubber with a MTEC not to exceed 5,800
g/dscm, or (3) a combination of venturi scrubber and IWS with
a MTEC less than 49,000

[[Page 24223]]

g/dscm. The proposed floor level was 270 g/dscm.
HWIs use a combination of good PM control and limiting hazardous
waste feedrates to control SVM emissions. SVMs, which typically
vaporize at combustion chamber temperatures and recondense onto small-
size particulates in the APCD, are controlled most efficiently by
technologies that are effective at capturing fine PM. EPA's revised
database shows that SVM emissions vary substantially from 2 to nearly
30,000 g/dscm.
The refined data analysis method used by EPA to evaluate and
identify a MACT floor would be based directly on the results from the
PM floor analyses discussed above. As mentioned there, a floor of 0.015
gr/dscf would appear to represent the MACT floor for HWIs based on good
PM control. Since SVMs are controlled, in part, by a well-designed and
operated PM control devices, it follows that sources achieving this PM
performance level at typical SVM feedrates should also be controlling
SVMs emissions.
Therefore, in its refined SVM analyses of the revised database, the
Agency first considers all SVM data when corresponding PM measurements
are below 0.015 gr/dscf. To identify the SVM floor from these data, we
would determine either the highest SVM test condition average or the
level that excludes sources achieving substantially poorer SVM control
than the majority of sources. It is most likely appropriate to use the
latter approach--excluding sources with significantly poorer SVM
performance--because their higher SVM emissions may be the result of
exceedingly high SVM feedrates or some other factor that cannot be
readily identified with available information (e.g., sampling or
analysis anomalies). An SVM emissions breakpoint analysis is the
approach for excluding these poorer performing test conditions.
Applying this evaluation technique to the revised HWI SVM database
results in a MACT floor of 100 g/dscm. Approximately 53
percent of all HWI SVM test condition data, regardless of PM emissions
level, are currently achieving this emissions level.
As discussed above for PM, the Agency is soliciting comment on an
alternative evaluation of the HWI PM data which identified a floor of
0.029 gr/dscf. Conducting the same SVM floor analysis discussed above
when PM measurements were below 0.029 gr/dscf also results in the same
floor of 240 g/dscm. Approximately 60 percent of all HWI SVM
test condition data, regardless of PM emissions level, are currently
achieving this emissions level.
Finally, as discussed in an earlier section, a preliminary analysis
indicates that MACT standards may not be warranted for one HAP metal,
antimony. Since the number of metals being considered for MACT
standards may change, we are investigating the appropriate structure of
metals standards (e.g., retain the volatility groups or establish
individual metals standards). Using the refined method discussed above
for SVM, we analyzed the revised database with respect to Cd and Pb
data. The floor analysis corresponding to PM measurements below 0.015
gr/dscf would result in the following floor levels: Cd 20 g/
dscm, and Pb 95 g/dscm. The alternative data analysis method
for individual metals when corresponding PM measurements were below
0.029 gr/dscf would result in the following floor levels: Cd 57
g/dscm, and Pb 95 g/dscm.
b. BTF considerations for existing sources. In the NPRM, the Agency
considered a BTF standard for SVMs based on improved PM control below
0.030 gr/dscf. However, the Agency concluded that a BTF standard would
not be cost-effective given that the floor level alone would result in
an estimated 94 percent SVM reduction in emissions.
As discussed for PM BTF considerations, we also re-evaluated the
possible appropriateness of using a reduced PM emissions level based on
improved PM control as a BTF standard (taking into consideration
corresponding BTF reductions in SVMs) for existing HWIs. Given that the
alternative PM floor level analyses presented today would be lower than
the proposed floor and BTF floor levels, significant cost-effectiveness
considerations emerge and suggest that a BTF standard for either SVMs
or individual Pb or Cd standards based on improved PM control may not
ultimately prove to be cost-effective.
If, however, the revised risk assessment yet to be conducted would
show significant risk at a SVM floor standard of either 100 g/
dscm or 240 g/dscm, which are floor levels from the two data
analysis methods discussed above, the Agency will determine whether a
BTF standard based on control of SVM feedrate to levels below those at
the floor would be appropriate. This feedrate limitation would in turn
reduce SVM emissions. The BTF standard and the corresponding level of
feedrate control would be dictated by considerations of cost-
effectiveness and the need to establish more stringent RCRA-related
controls.
c. MACT floor for new sources. At proposal, the Agency defined
floor control, based on the best performing source, as a combination of
venturi scrubber and IWS with a MTEC less than 49,000 g/dscm.
The proposed floor level for new HWIs was 240 g/dscm.
Based upon our re-evaluation of the database, the floor control and
emission level discussed above for existing sources for PM and SVMs
would also appear to be appropriate for new sources. In this event,
MACT floor control would be a well-designed, operated and maintained PM
control device (e.g., fabric filter, IWS, or ESP) achieving the PM
floor level of 0.015 gr/dscf, and the MACT floor would be around 100
g/dscm.
As discussed above, the Agency is soliciting comment on an
alternative evaluation of the revised SVM database which concludes that
MACT floor control is a well designed, operated and maintained PM
control device (i.e., fabric filter, IWS, or ESP) achieving a PM level
of 0.029 gr/dscf. The floor analysis considering all revised SVM data
when corresponding PM measurements are below 0.029 gr/dscf results in a
floor for new sources of 240 g/dscm.
Finally, we have evaluated what individual metal floor levels for
new sources would be. When PM measurements are below 0.015 gr/dscf, the
analysis would result in floor levels for Cd of 20 g/dscm and
for Pb 95 g/dscm. Under the alternative data analysis method
for individual metals when PM measurements were below 0.029 gr/dscf,
floor levels would be 57 g/dscm for Cd and 95 g/dscm
for Pb.
d. BTF considerations for new sources. In the NPRM, the Agency
proposed a BTF level of 62 g/dscm based on improved PM control
below 0.030 gr/dscf.
As discussed for PM, a reduced PM emissions level based on improved
PM control could be considered in evaluating a potential BTF standard
(considering corresponding BTF reductions in SVMs and LVMs) for new
HWIs. Because the PM floor level presented today would be substantially
lower than the proposed floor and proposed BTF floor level, cost-
effectiveness issues are again raised and suggest that a BTF standard
for either SVMs or individual Pb or Cd standards based on improved PM
control may likewise ultimately prove to be inappropriate.
6. Low volatile metals (LVM) (arsenic, beryllium, and chromium). a.
MACT Floor for Existing Sources. At proposal, EPA defined floor control
as either (1) a venturi scrubber with a MTEC not to exceed 1,000
g/dscm, or (2) an IWS with a MTEC less than 6,200 g/
dscm.

[[Page 24224]]

The proposed floor level was 210 g/dscm, which included
antimony.
HWIs use a combination of good PM control and limiting hazardous
waste feedrates to control LVM emissions. LVMs are less likely to
vaporize at combustion temperatures and therefore partition primarily
to the residue or adsorb onto particles in the combustion gas. EPA's
database shows that LVM emissions from HWIs vary widely from 1 to over
130,000 g/dscm.
To identify a LVM MACT floor, the Agency used the same data
analysis method applied to the revised SVM database. As was determined
in the PM analysis of the revised database, a floor of 0.015 gr/dscf
represents MACT for HWIs based on good PM control. Considering all LVM
data from sources achieving a PM level 0.015 gr/dscf or better, the
Agency's evaluation of the revised HWI data results in a LVM floor of
55 g/dscm (excluding sources above a breakpoint and therefore
achieving substantially poorer LVM emissions than the majority of
sources). Over 70 percent of HWI LVM test condition data are currently
achieving this emissions level.
As discussed earlier, the Agency is soliciting comment on an
alternative evaluation of the revised HWI PM data which identified a
floor of 0.029 gr/dscf. Evaluating the revised LVM data using this
method results in a LVM floor of 190 g/dscm. Approximately 90
percent of HWI LVM test condition data are currently achieving this
level.
Finally, as discussed in an earlier section, a preliminary analysis
indicates that MACT standards may not be warranted for one HAP,
antimony. Since the number of metals being considered for MACT
standards may change, we are investigating the appropriate structure of
metals standards (e.g., retain the volatility groups or establish
individual metals standards). Using the refined method discussed above
for LVM, we analyzed the revised database with respect to As, Be, and
Cr (hexavalent). The floor analysis corresponding to PM measurements
below 0.015 gr/dscf results in the following floor levels: As 21
g/dscm, Be 2 g/dscm, and Cr (hexavalent) 3
g/dscm. The alternative data analysis method for individual
metals when corresponding PM measurements were below 0.029 gr/dscf
results in the following Floor levels: As 21 g/dscm, Be 2
g/dscm, and Cr (hexavalent) 5.5 g/dscm.
The Agency is concerned that some of the potential floor standards
for some individual metals (e.g., Be, Cr (hexavalent)) may be present
at levels approaching practical quantitation limits (PQLs). PQLs are
the lowest level of quantification that the Agency believes a competent
analytical laboratory can be expected to reliably achieve. The Agency
will investigate whether this issue may need to be addressed in the
development of any individual metals standards that may be considered
for the final rulemaking. We invite comment on the issue of PQLs and
LVM BTF standards.
b. BTF considerations for existing sources. In the NPRM, the Agency
considered a BTF standard for LVMs based on improved PM control below
0.030 gr/dscf. However, the Agency concluded that a BTF standard would
not be cost-effective given that the floor level alone would result in
an estimated 91 percent LVM reduction in emissions.
As discussed for PM, a reduced PM emissions level based on improved
PM control could be considered in evaluating a potential BTF standard
(taking into consideration corresponding BTF reductions in LVMs and
SVMs) for existing HWIs. Because the PM floor level presented today
would be substantially lower than the proposed floor and BTF floor
levels, a BTF standard for either LVMs or individual As, Be, and Cr
(hexavalent) standards based on improved PM control would raise
significant cost-effectiveness concerns and may not be appropriate.
If, however, the revised risk assessment yet to be conducted would
show significant risk at a LVM floor standard of either 55 g/
dscm or 190 g/dscm, which are floor levels from the two data
analysis methods discussed above, the Agency will determine whether a
BTF standard based on control of LVM feedrate to levels below those at
the floor would be appropriate. This feedrate limitation would in turn
reduce LVM emissions. The BTF standard and the corresponding level of
feedrate control would be dictated by considerations of cost-
effectiveness and the need to establish more stringent RCRA-related
controls.
c. MACT floor for new sources. At proposal, the Agency defined
floor control, based on the best performing source, as a venturi
scrubber with a MTEC less than 1,000 g/dscm. The proposed
floor level for new HWIs was 260 g/dscm.
Based upon our re-evaluation of the database, the floor control and
emission level discussed above for existing sources for PM and LVMs
would also appear to be appropriate for new sources. MACT floor control
is a well-designed, operated and maintained PM control device (e.g.,
fabric filter, IWS, or ESP) achieving the PM floor level of 0.015 gr/
dscf, and analysis of the revised data results in a LVM MACT floor of
55 g/dscm.
As discussed above, the Agency is soliciting comment on an
alternative evaluation of the revised LVM database which identifies
MACT floor control as a well-designed, operated and maintained PM
control device (e.g., fabric filter, IWS, or ESP) achieving a PM level
of 0.029 gr/dscf. The floor analysis considering all revised LVM data
when corresponding PM measurements are below 0.029 gr/dscf results in a
floor for new sources of 190 g/dscm.
Finally, individual metal floor levels for new sources, when PM
measurements are below 0.015 gr/dscf, are: As 21 g/dscm, Be 2
g/dscm, and Cr (hexavalent) 3 g/dscm. Under the
alternative data analysis method for individual metals when PM
measurements are below 0.029 gr/dscf, the floor levels are: As 21
g/dscm, Be 2 g/dscm, and Cr (hexavalent) 5.5
g/dscm. [Note: The same PQL concerns would be present here as
well.]
d. BTF considerations for new sources. In the NPRM, the Agency
proposed a BTF level of 60 g/dscm based on improved PM control
below 0.030 gr/dscf.
As discussed for PM BTF considerations, the Agency considered a
reduced PM emissions level based on improved PM control as the BTF
standard (taking into consideration corresponding BTF reductions in
LVMs and SVMs) for new (and existing) HWIs. Because the alternative PM
floor level presented today is substantially lower than the proposed
floor and BTF floor levels, a BTF standard for either LVMs or
individual As, Be, or Cr (hexavalent) standards based on improved PM
control may be inappropriate in light of the cost-effectiveness issues
inherent in this scenario.
7. Hydrochloric Acid and Chlorine (HCl/Cl2). a. MACT Floor for
Existing Sources. At proposal, the Agency defined floor control as wet
scrubbing with a chlorine MTEC (i.e., maximum theoretical emission
concentration) up to 2.1E7 ``g/dscm and proposed a floor
standard of 280 ppmv. While evaluating the revised database, we
investigated another data analysis method whereby floor control would
be defined as wet scrubbing combined with chlorine feedrate control to
achieve an emission level of 75 ppmv.²⁸ Under this method,

[[Page 24225]]

emissions data from sources using wet or dry scrubbing were arrayed
from lowest to highest (without explicit regard to chlorine feedrate)
and sources achieving substantially poorer HCl/Cl2 control than other
sources were screened from the analysis. Accordingly, after five of 48
test conditions were screened from the analysis for anomalously high
emission rates,²⁹ the floor standard was established as the
highest remaining test condition average--75 ppmv.³⁰ Nearly
90 percent of test conditions ³¹ in the revised database
have emission levels below 75 ppmv.
---------------------------------------------------------------------------

\28\ Although a specific feedrate (i.e., MTEC) level is not used
to define MACT floor, feedrate control is part of floor control to
achieve the 75 ppmv standard using wet scrubbing (i.e., a source
would probably not be able to feed chlorine at extremely high rates
and still achieve the standard using wet scrubbing). Further, as
discussed below in the text, sources with anomalously high emissions
were screened from consideration. One reason that a source may have
anomalously high emissions is that it may be feeding unusually high
levels of chlorine.
\29\ The anomalously high emissions could have been caused by:
(1) Poor design, operation, or maintenance of the scrubber, and thus
the device would not represent MACT (e.g., a dry scrubber was
screened from the analysis because dry scrubbers are generally less
efficient than wet scrubbers); (2) unusually high chlorine
feedrates; or (3) sampling or analysis anomalies.
\30\ The floor standard under this alternative analysis method--
75 ppmv--would be substantially lower than the proposed floor
standard--280 ppmv--even though feedrate control of chlorine would
not be used explicitly to help define floor control under this
alternative method because, to identify the proposed standard, the
Agency: (1) Selected as the standard-setting test condition the
highest test condition for sources appearing to be using floor
control without screening anomalous test conditions; and (2) added a
computed emissions variability factor to emissions from that
standard-setting test condition.
\31\ Considering approximately 50 test conditions where
emissions levels on both HCl and Cl2 were available.
---------------------------------------------------------------------------

The Agency requests comment on whether this alternative approach to
define floor control and a floor level would be more appropriate than
the proposed approach.
b. BTF considerations for existing sources. At proposal, the Agency
determined that a BTF standard would not be warranted. Specifically,
the Agency noted that risk from emissions at the floor standard would
not likely trigger the need for additional control under RCRA.
Although that may prove to be the case as well for the alternative
standard discussed in today's notice (i.e., 75 ppmv), the risk
assessment accompanying the final rule will consider incinerators with
short stacks and will also consider acute risk from HCl and Cl2 during
short-term exposures. The risk assessment at proposal modeled emissions
only from incinerators with relatively tall stacks, and did not
consider acute exposure to HCl and Cl2. If, however, the revised risk
assessment yet to be conducted shows significant risk at a floor
standard of 75 ppmv, the Agency will determine whether a BTF standard
would be appropriate considering cost-effectiveness of such a standard
and the need to establish more stringent controls under RCRA. In that
case, BTF control could be based on a minimum system removal efficiency
(e.g., 99.9 percent) and/or control of chlorine feedrate.
c. MACT floor for new sources. At proposal, the Agency identified
floor control for new incinerators as wet scrubbing with an MTEC of
1.7E7 g/dcsm See 61 FR at 17388. Although the floor control
for new sources was based on the single best performing source and was
more stringent than floor control for existing sources, the floor
emission level was the same for new and existing sources: 280 ppmv.
When evaluating the revised emissions database considering various
data analyses methods for today's notice, we determined that floor
control for new sources should be the same as for existing sources: Wet
scrubbing with chlorine feedrate control to achieve an emission level
of 75 ppmv. This is state-of-the-art control for these HAPs.
Accordingly, the floor standard for new sources would be 75 ppmv under
this data analysis method.
d. BTF considerations for new sources. The Agency proposed BTF
control for new incinerators as 99 percent SRE and a BTF standard of 67
ppmv. This standard was based on applying 99 percent reduction to the
test condition in the database with the highest average emission
without an emission control device (i.e., 1100 ppmv). Then, considering
other factors including a computed emissions variability factor, the
Agency determined that a BTF standard of 67 ppmv would be appropriate.
In retrospect, as we discussed above, virtually all sources are
already equipped with some form of scrubber and 90 percent are
achieving emission levels of 75 ppmv or below. Thus, this would be an
appropriate floor control and standard for new sources. As discussed
above for existing sources, a BTF standard appears to be unnecessary,
unless the upcoming final risk analysis indicates that more stringent
controls under RCRA would be warranted. A BTF standard could be based
on a minimum system removal efficiency (e.g., 99.9 percent) and/or
control of chlorine feedrate.
8. Carbon Monoxide (CO). As proposed, the Agency continues to
believe that floor control for CO (as a surrogate for organic HAPs) for
both existing and new sources would be operation under good combustion
practices. The preponderance of the revised emissions data indicate
that a floor standard of 100 ppmv over an hourly rolling average (HRA)
would be readily achievable. In addition, the Agency continues to
believe that a BTF standard for CO based on better good combustion
practices is likely to raise significant cost-effectiveness
considerations.
9. Hydrocarbons (HC). The Agency proposed that floor control for HC
(as a surrogate for otherwise unaddressed organic HAPs) for both
existing and new sources would be operated under good combustion
practices and that a floor standard of 12 ppmv over an hourly rolling
average (HRA), would be appropriate. In evaluating the revised emission
database for today's notice, we used the same general approach for HC
as at proposal--the entire database was arrayed from the lowest to the
highest emission levels and assumed that test conditions beyond a
breakpoint were not operated under good combustion practices. Based on
that analysis, a floor level for HC of 10 ppmv, HRA, results. (This 10
ppmv standard does not include a variability factor for reasons
discussed above, unlike the proposed standard of 12 ppmv that did.) Not
only does the revised database show that the preponderance of the data
are below 10 ppmv, but engineering experience and other engineering
information suggests that a HC level of 10 ppmv is readily achievable
using good combustion practices.
As discussed at proposal, the Agency continues to be concerned
about cost-effectiveness considerations related to BTF controls for HC
based on operating under better combustion practices.
F. Re-Evaluation of Proposed MACT Standards for Cement Kilns
We discuss in this section the basis for the revised standards for
cement kilns that result from applying engineering and data analysis to
the revised emissions database.³² A comparison of the
proposed and potentially revised standards for existing and new sources
is presented in the table below:
---------------------------------------------------------------------------

\32\ Additional details of the engineering and data analysis
evaluations performed on the revised emissions database can be found
in the Agency's background document: USEPA, ``Draft Technical
Support Document for HWC MACT Standards (NODA), Volume I: MACT
Evaluations Based on Revised Database'', April 1997.

[[Page 24226]]

Table II.F.--Revised Standards for Existing and New Cement Kilns
----------------------------------------------------------------------------------------------------------------
Existing sources New sources
-------------------------------------------------------
HAP or HAP Surrogate Proposed Revised Proposed Revised
standard standard standard standard
----------------------------------------------------------------------------------------------------------------
D/F (ng TEQ/dscm)....................................... \1\ 0.20 0.20 0.20 0.20
Hg (g/dscm).................................... 50 72 50 72
PM (gr/dscf)............................................ 0.030 0.030 0.030 0.030
HCl/Cl2 (ppmv).......................................... 630 120 67 120
CO (ppmv)............................................... 100 100 100 100
HC (ppmv):
Main Stack \2\...................................... 20 20 20 20
By-Pass............................................. 6.7 10 6.7 10
SVM (g/dscm)................................... 57 670 55 670
LVM (g/dscm)................................... 130 63 44 63
----------------------------------------------------------------------------------------------------------------
\1\ All emission levels are corrected to 7% O2.
\2\ Not applicable to preheater and/or precalciner kilns.

1. Subcategorization considerations. After analyzing comments
submitted by the Cement Kiln Recycling Coalition (CKRC) on the proposed
rule, including information on the types of cement kilns that are
currently burning hazardous waste, we considered whether the following
subcategories would be appropriate: (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
(i.e., wet kilns, and long dry kilns not using raw mill drying). Each
of the first three categories is comprised of only one cement kiln
facility while the kilns at the remaining 19 facilities are in the
fourth category: wet kilns or long dry kilns that do not use raw mill
drying. We find that these subcategories should be considered because
the unique design or operating features of these kilns could have a
significant impact on emissions of one or more HAPs that the Agency
proposed to regulate.
To determine whether special standards would be appropriate for any
of the three unique cement kiln types, we identified floor control and
emission levels considering data only for the other kilns (i.e., wet
kilns, and long dry kilns not using raw mill drying). We then
considered whether the unique kiln types could apply the those MACT
controls and achieve those emission standards. It appears that these
unique kilns can employ the MACT controls and achieve the corresponding
emission levels identified in today's notice for the other kilns (i.e.,
wet kilns, and long dry kilns not using raw mill drying). Thus,
subcategorization would not appear to be needed to determine achievable
MACT floors for all cement kilns burning hazardous waste.
2. Dioxins and Furans (D/F). a. MACT Floor for Existing Sources. At
proposal, the Agency identified floor control as ``temperature control
at the inlet to the ESP or fabric filter at 418 deg.F''. The proposed
floor emission level was ``0.20 ng TEQ/dscm, or temperature at the
inlet to the ESP or fabric filter not to exceed 418 deg.F''.
Upon re-evaluation of the revised database, we have identified an
alternative data analysis method that seems more appropriate to
identify floor control and the floor emission level. Based on an
engineering evaluation of these data and other available information,
floor control would be ``temperature control at the inlet to the ESP or
fabric filter at 400 deg.F''. This results in a floor emission level
of ``0.20 ng TEQ/dscm, or 0.40 ng TEQ/dscm and temperature at the inlet
to the ESP or fabric filter not to exceed 400 deg.F''.³³
---------------------------------------------------------------------------

\33\ The standard would be expressed in the form of a TEQ level
combined with a maximum temperature at the PM control device. This
form of the standard is consistent with the revised data and would
result in somewhat lower emissions (i.e., because without the TEQ
limit, some sources could exceed that TEQ level at the specified
temperature). Thus, expressing the standard in this form better
achieves the statutory mandate to establish standards that provide
the maximum degree of reduction that is achievable in practice.
---------------------------------------------------------------------------

Temperature control to 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 D/F
formation is 450-750 deg.F; and (2) below 350 deg.F, kiln gas can
fall below the dew point which can increase corrosion in ESPs and
fabric filters and reduce performance of the control devices. In
addition, approximately 20 percent of the test conditions in our
revised database reflect operations at temperatures of 400 deg.F or
below. Thus, this temperature level is readily achievable.
To identify an emission level that temperature control
400 deg.F could achieve, it is appropriate to pool the
available emissions data for hazardous waste burning kilns with data
from nonwaste burning kilns.³⁴ This is because we are not
aware of an engineering reason why hazardous waste burning would affect
emissions of D/F. In fact, when the data sets are evaluated separately,
the highest emitting HW cement kiln operating the ESP or fabric filter
at temperatures 400 deg.F had D/F emissions of 0.28 ng TEQ/
dscm. The highest emitting nonwaste cement kiln operating at those
temperatures had D/F emissions of 0.37 ng TEQ/dscm. We believe that the
difference in emission levels is simply a reflection of many design,
operation, and maintenance factors on which we have little or no
information, but which could affect D/F emission levels. An appropriate
emission level associated with that operating temperature for all
cement kilns would be 0.40 ng TEQ/dscm. Thus, the floor standard would
be: ``0.20 ng TEQ/dscm, or 0.40 ng TEQ/dscm and temperature at the
inlet to the ESP or fabric filter not to exceed 400 deg.F''.
---------------------------------------------------------------------------

\34\ We considered whether nonwaste cement kiln emission data
should be pooled with HW cement kiln data for other HAPs and
determined that emissions of other HAPs, except for PM, could be
affected by hazardous waste burning. For example, hazardous waste
can have higher levels of chlorine and metals such as Pb. With
respect to PM, although it appears appropriate to pool the data
sets, the better-suited data analysis method is based on the New
Source Performance Standard, not an analysis of the emissions
database. Thus, pooling of data would not affect the standard
derived from that data analysis method. See discussion on the PM
standard in the text.
---------------------------------------------------------------------------

b. BTF considerations for existing sources. The Agency proposed a
BTF standard of 0.20 ng TEQ/dscm based on ACI operated at a temperature
of 400

[[Page 24227]]

deg.F. We continue to believe that this BTF standard is appropriate
given the concerns the Agency has expressed about the risks posed by D/
F emissions, and the Hg reductions that ACI would also provide. See 61
FR at 17392. Only sources emitting between 0.20 and 0.40 ng TEQ/dscm
with temperature control alone would need to take further measures to
reduce D/F levels to 0.20 ng under the BTF standard. Although these
sources could achieve D/F emission levels well below 0.20 ng TEQ/dscm
using ACI (i.e., ACI removal efficiency should be in the 95-99 percent
range), a 0.20 ng TEQ/dscm appears still to be appropriate because it
may allow some sources to meet the standard more cost-effectively by
lowering gas temperatures at the ESP or fabric filter below 400 deg.F.
Further, a BTF standard of 0.20 ng TEQ/dscm would likely avoid the need
to provide further controls under RCRA authority.
c. MACT floor for new sources. At proposal, the Agency identified
floor control for new sources as ``temperature control at the inlet to
the ESP or fabric filter at 409 deg.F''. The proposed floor emission
level was ``0.20 ng TEQ/dscm, or temperature at the inlet to the ESP or
fabric filter not to exceed 409 deg.F''.
Upon evaluation of the revised database, the floor control and
emission level discussed above for existing sources would also be
appropriate for new sources (i.e., ``temperature control at the inlet
to the ESP or fabric filter at 400 deg.F'' corresponding to an
emission level of ``0.20 ng TEQ/dscm, or 0.40 ng TEQ/dscm and
temperature at the inlet to the ESP or fabric filter not to exceed 400
deg.F''. This is because our engineering evaluation of available
information and facility operating experience indicates that the best
controlled source is one that is controlling temperature control at the
inlet to the fabric filter at 400 deg.F.
d. BTF considerations for new sources. The Agency proposed ACI as
BTF control and a BTF standard of 0.20 ng TEQ/dscm. We continue to
believe that this BTF standard is appropriate for new sources for the
same reasons discussed above in the context of existing sources.
3. Mercury (Hg). a. MACT floor for existing sources. At proposal,
the Agency identified floor control as hazardous waste feedrate control
not to exceed an MTEC of 110 g/dscm. EPA proposed a floor
standard of 130 g/dscm.
All cement kilns employ either ESPs and fabric filters for PM
control. However, since Hg is generally in the vapor form in and
downstream of the combustion chamber, including the air pollution
control device, ESPs and fabric filters do not achieve good mercury
control. Mercury emissions from cement kilns are currently controlled
by the BIF rule which establishes limits on the maximum feedrate of Hg
in total feedstreams (e.g., hazardous waste, raw materials, coal).
Thus, MACT is based on hazardous waste feed control.
Review of the revised database indicate that cement kilns only
infrequently conducted Hg spiking of the hazardous wastes (contrary to
the Agency's initial information), and thus the Hg content in the
wastes during testing is likely representative of the Hg content during
typical operations. The revised data also show that raw materials can
represent a significant source Hg input to the kiln system. Since
cement kilns do not employ a dedicated device capable of Hg control,
the Agency believes that the Hg data are essentially ``normal'' even
though generated during worst case compliance testing conditions for
other parameters.
To evaluate these revised data for the purpose of determining a
MACT floor, the Agency used the following data analysis steps: (1) Rank
Hg emissions from lowest to highest; (2) conduct a breakpoint analysis
on the ranked Hg emissions data, and (3) establish the floor standard
as the test condition average of the breakpoint source. The breakpoint
analysis reflects an engineering-based evaluation of the data and
ensures that the few cement kilns spiking extra Hg do not drive the
floor level to levels higher than the preponderance of this ``normal''
data indicates is routinely achievable. The Agency's analysis results
in a MACT floor level of 72 g/dscm. The revised database
indicates that approximately 80 percent of cement kilns are achieving
this floor level.
b. BTF considerations for existing sources. The Agency proposed a
BTF standard of 50 g/dscm based on flue gas temperature
reduction to 400 deg.F or less followed by ACI. EPA continues to
believe that ACI is an appropriate BTF technology for cement kilns.
Although ACI is not employed for Hg control at any full-scale HW cement
kiln, the Agency is not aware of any cement kiln flue gas conditions
that would preclude the applicability of ACI--which has been
demonstrated for other similar types of combustion applications. As
discussed in the NPRM, EPA assumes that cement kilns employing ACI to
meet a BTF standard would install the ACI system after the existing ESP
or fabric filter, and then add on a new fabric filter to remove the
injected carbon with the adsorbed Hg. Although adding a new fabric
filter in series is an expensive approach, it will enable cement kilns
to continue current cement kiln dust (CKD) recycling practices by
avoiding potential internal build-up of Hg from CKD recycling.
In the NPRM, the cement kiln BTF standard was based on the
assumption that an ACI system could routinely achieve Hg emissions
reductions of 80 to 90 percent. The Agency received public comments
from, among others, the cement manufacturing industry questioning
whether a ACI application on a cement kiln could routinely achieve
capture efficiencies as proposed. The commenters went on to say that
removal efficiencies of approximately 60 percent were perhaps more
realistic. We will address these comments specifically as part in the
final rulemaking, but for the purposes of today's analysis, EPA has
assumed an ACI effectiveness of 60 percent in identifying BTF levels
for cement kilns. Thus, the BTF standard for cement kilns would be 30
g/dscm based on an ACI efficiency of 60 percent applied to the
potential floor level of 72 g/dscm.
Ultimately adopting a BTF standard of 30 g/dscm for cement
kilns will likely involve close scrutiny of cost-effectiveness and
other factors, including the costs of retrofits that sources will need
to undertake (e.g., installing the ACI system, add-on of a new fabric
filter, managing the captured carbon) relative to the emissions
reductions achieved. Without pre-judging this issue, the Agency's
experience to date suggests that the final analysis may well reveal
significant drawbacks associated with the BTF level.
c. MACT floor for new sources. At proposal, the Agency identified
floor control for new sources as hazardous waste feedrate control not
to exceed an MTEC of 28 g/dscm. EPA proposed a floor standard
of 82 g/dscm.
The Agency believes that the floor control and emission level
discussed above for existing sources would also be appropriate for new
sources. Thus, the MACT floor for new cement kilns would be 72
g/dscm based on the revised database.
d. BTF considerations for new sources. At proposal, BTF for new
sources was based on ACI and we proposed a BTF standard of 50
g/dscm.
As discussed for existing sources, the Agency is considering the
use of ACI and flue gas temperature reduction to 400 deg.F as the BTF
technology. In evaluating the revised database, EPA has identified a
level of 30 g/dscm as the BTF standard for new sources based
on ACI. This is based on a source achieving the MACT new floor level of

[[Page 24228]]

72 g/dscm and then applying ACI with a 60 percent removal
efficiency. For the same reasons identified for existing sources, the
Agency is concerned about whether this BTF level based on ACI will
ultimately prove to be cost-effective for new cement kiln sources.
4. Particulate Matter (PM). a. MACT floor for existing sources. At
proposal, EPA defined floor control as a fabric filter with an air-to-
cloth ratio of 2.3 acfm/ft². The floor analysis led to a
level of 0.065 gr/dscf, but due to concerns with the appropriateness of
using a statistically-derived variability factor, the Agency instead
established the floor standard based on the cement kiln New Source
Performance Standard (NSPS). The NSPS is a process emissions rate that
converts to an approximate flue gas concentration of 0.03 gr/dscf.
Today, EPA is taking comment on two data analysis methods to
identify the PM floor standard for cement kilns. The first data
analysis method would be to establish the floor standard equivalent to
the NSPS, which is 0.3 lbs PM per ton of dry raw material feed.
Currently, approximately 20 percent of HW cement kilns are subject to
the NSPS. Cement kilns achieve the NSPS with well-designed and properly
operated ESPs or fabric filters.
A second data analysis method considered and potentially preferred
would be to express the NSPS as a stack gas concentration limit as done
in the NPRM. The conversion of the NSPS to a concentration standard
will vary by kiln process type (e.g., wet, dry, preheater, preheater/
precalciner) because the amount of flue gas generated per ton of raw
material feed varies by process type. Based on typical factors of flue
gas quantities generated per ton of raw material feed and flue gas
moisture content, the NSPS equates to a PM concentration of
approximately 0.03 gr/dscf for wet process kilns (also the least energy
efficient) and 0.05 gr/dscf for preheater kilns (the most energy
efficient). The total HW cement kiln universe is comprised of 41 kilns
with varying process types: 27 wet, 12 long dry, one preheater/
precalciner, and one preheater. Of the cement kilns currently subject
to the NSPS standard, four are wet, two are long dry, one preheater/
precalciner, and one preheater.
Notwithstanding that the concentration equivalent of the NSPS can
vary by process type, establishing the floor standard for all cement
kilns at 0.030 gr/dscf appears to be appropriate regardless of
manufacturing process utilized, for the following reasons: (1) The
majority (66 percent) of the cement kilns are wet process kilns for
which the NSPS concentration equivalent is 0.030 gr/dscf. For these
kilns, this floor method would not differ from the initial NSPS method
used in the proposal. (2) Our database shows non-wet process kilns have
at least one test condition (in addition to three quarters of all non-
wet process kiln data) achieving 0.030 gr/dscf. Therefore,
achievability of the floor appears to be satisfied. (3) Even though wet
process kilns typically have lower inlet grain loadings than the non-
wet processes, non-wet kilns are achieving the 0.030 gr/dscf level.
Again, the achievability requirement is met. Thus, the Agency believes
that it is appropriate to establish the MACT floor for existing sources
at 0.030 gr/dscf.
In the NPRM, the Agency proposed that sources maintain continuous
compliance with the PM standard through the use of a PM CEMS. A
decision whether to require cement kilns to install a PM CEMS will be
made at the completion of an on-going demonstration testing program to
determine if at least one PM CEMS can meet the proposed performance
specifications. Since the floor standards discussed above were based on
manual test method data, the Agency will re-evaluate at the completion
of the CEMS testing program whether these PM floor standards would be
appropriate in the event that the final rulemaking requires continuous
compliance with a PM CEMS. The Agency will make available the results
and conclusions of the demonstration test program in the docket for the
HWC rule.
b. BTF considerations for existing sources. In the NPRM, the Agency
considered a BTF level of 0.015 gr/dscf based on improved PM control.
However, we determined that such a standard would not likely be cost-
effective. We did not have adequate data to ensure that, given the high
inlet grain loading caused by entrained raw material, cement kilns
could routinely achieve 0.015 gr/dscf and below with a single fabric
filter or ESP.
In light of the revised database, the Agency again considered a BTF
PM emissions level based on improved PM control. Because the floor
level of 0.030 gr/dscf presented today is the same as the proposed
floor, a BTF standard lower than 0.030 gr/dscf (even with corresponding
BTF reductions for SVMs and LVMs) appears not to be cost-effective
based on information developed at proposal.
c. MACT floor for new sources. At proposal, the Agency defined
floor control as a fabric filter with an air-to-cloth ratio of less
than 1.8 acfm/ft². The floor analysis lead to a level of
0.065 gr/dscf. Due to concerns with the appropriateness of the
statistically-derived variability factor, the Agency instead
established the floor standard based on the cement kiln NSPS. The NSPS
is a process emissions rate that the Agency converted to an approximate
flue gas concentration of 0.030 gr/dscf.
Upon evaluation of the revised database discussed for existing
sources, EPA continues to believe that the floor standard discussed
above for existing sources would also be appropriate for new sources.
Therefore, MACT floor control is a well-designed and properly operated
PM control device (e.g., fabric filter, ESP), and the MACT floor for
new cement kilns would be 0.030 gr/dscf.
d. BTF considerations for new sources. In the NPRM, EPA considered
a BTF standard based on improved PM control to be consistent with
existing sources. However, we found that the BTF level would not be
cost-effective.
Today, as discussed above for existing source BTF considerations
and based upon examining the revised database in light of the findings
at proposal, a BTF standard beyond a PM level of 0.030 gr/dscf (and
corresponding BTF reductions for SVMs and LVMs) would not appear to be
cost-effective.
5. Semivolatile Metals (SVM) (cadmium and lead). a. MACT Floor for
Existing Sources. At proposal, EPA defined floor control as a fabric
filter with an air-to-cloth ratio less than 2.1 acfm/ft²and
a HW MTEC of 84,000 g/dscm. The proposed floor level was 57
g/dscm.
Cement kilns use a combination of good PM control and limiting
hazardous waste feedrates to control SVM emissions. SVMs are controlled
most efficiently by technologies, such as fabric filters, which are
effective at capturing fine PM. EPA's database shows that SVM emissions
vary substantially from 1 to over 6,000 g/dscm.
The engineering evaluation and data analysis method used by EPA to
evaluate and identify a MACT floor from the revised database is an
extension of the PM floor analyses of the revised database. As
discussed in the PM analysis, a floor of 0.030 gr/dscf could represent
MACT based on good PM control. Since SVMs are controlled, in part, by a
well-designed and operated PM control device, it follows that sources
achieving this PM performance level should also be controlling SVM
emissions at typical SVM feedrates. Therefore, in its refined SVM
analysis of the revised database, EPA would first consider all SVM data
when corresponding PM measurements are below 0.030 gr/dscf. To identify
the SVM floor from these data, we would identify the floor at the level
that

[[Page 24229]]

excludes (by breakpoint analysis) sources achieving substantially
poorer SVM control than the majority of sources. As noted earlier in
the case of HWIs, it is appropriate to exclude sources with
significantly poorer SVM performance because their higher SVM emissions
may be the result of exceedingly high SVM feedrates or some other
factor that shows the test condition did not actually reflect MACT
floor controls. The Agency does not have available information to
otherwise screen out these non-MACT test conditions from the expanded
universe for SVM.
The Agency's evaluation of the revised cement kiln SVMs data
results in a MACT floor of approximately 670 g/dscm.
Approximately 85 percent of SVM test condition data are currently
achieving this emissions level.
Finally, as discussed in an earlier section, a preliminary analysis
indicates that MACT standards may not be warranted for one HAP metal,
antimony. Since the number of metals being considered for MACT
standards may change, we are investigating the appropriate structure of
metals standards (e.g., retain the volatility groups or establish
individual metals standards). Using the refined method discussed above
for SVM, we analyzed the revised database with respect to Cd and Pb
data. The floor analysis corresponding to PM measurements below 0.030
gr/dscf would result in the following floor levels: Cd 60 g/
dscm, and Pb 560 g/dscm.
b. BTF considerations for existing sources. In the NPRM, the Agency
considered a BTF standard for SVMs based on improved PM control below
0.030 gr/dscf. However, the Agency concluded that a BTF standard would
not be cost-effective given that the SVM Floor level of 57 g/
dscm alone would result in an estimated 94 percent SVM reduction in
emissions.
As discussed for PM BTF considerations, the Agency also re-
evaluated the possible appropriateness of using a reduced PM emissions
level based on improved PM control as a BTF standard (with
corresponding BTF reductions in SVMs and LVMs). Even though the SVM
floor standard is higher than at proposal, our preliminary judgment is
that significant cost-effectiveness considerations will likely be
encountered in a final analysis of whether to establish a BTF standard
for either SVMs or for Pb or Cd individually.
If, however, the revised risk assessment yet to be conducted would
show significant risk at a SVM floor standard of either 670 g/
dscm, the Agency will determine whether a BTF standard based on control
of HW SVM feedrate to levels below those at the floor would be
appropriate. This feedrate limitation would in turn reduce SVM
emissions. The BTF standard and the corresponding level of feedrate
control would be dictated by considerations of cost-effectiveness and
the need to establish more stringent RCRA-related controls.
c. MACT floor for new sources. At proposal, the Agency defined
floor control, based on the best performing source, as a fabric filter
with an air-to-cloth ratio less than 2.1 acfm/ft² and a HW
MTEC of 36,000 g/dscm The proposed floor level for new cement
kilns was 55 g/dscm.
Upon evaluation of the revised database, EPA believes that the
floor control and emission level discussed above for existing sources
for SVMs would also be appropriate for new sources. In this event, MACT
floor control would be a well-designed, operated and maintained PM
control device (i.e., fabric filter or ESP) achieving the PM floor
level of 0.030 gr/dscf. The Agency's evaluation of the revised SVM data
results in a MACT floor of 670 g/dscm.
Finally, based on the revised database, individual metal floor
levels for new sources are identical to those for existing sources.
Thus, individual Cd and Pb standards are: Cd 65 g/dscm and Pb
550 g/dscm.
d. BTF Considerations for new sources. In the NPRM, the Agency
considered a SVM BTF level, but determined that a BTF standard would
not be cost-effective.
As discussed for existing sources, the Agency considered a more
stringent PM emissions level for improved control of PM, SVM and LVM
emissions for new cement kilns in light of the revised database. Even
though the SVM floor standard is higher than at proposal, our
preliminary judgment is that significant cost-effectiveness
considerations will likely be encountered in a final analysis of
whether to establish a BTF standard for either SVMs or for Pb or Cd
individually.
6. Low Volatile Metals (LVM) (arsenic, beryllium, and chromium). a.
MACT floor for existing sources. At proposal, EPA defined floor control
as either (1) a fabric filter with an air-to-cloth ratio less than 2.3
acfm/ft ² and a HW MTEC of 140,000 g/dscm, or (2)
an ESP with a specific collection area of 350 ft²/kacfm. The
proposed floor level was 130 g/dscm, which included antimony.
The engineering and data analysis method used by EPA to evaluate
the revised database and identify a MACT floor for LVMs is also related
directly to the PM floor analysis. As was determined in the PM
analysis, a floor of 0.030 gr/dscf represents MACT for cement kilns
based on good PM control. Considering all LVM data from sources
achieving a PM level 0.030 gr/dscf or better, EPA's evaluation of the
revised cement kiln data would result in a LVM floor of 63 g/
dscm (excluding sources above a breakpoint and therefore excluding
those with substantially poorer LVM emissions than the majority of
sources). Approximately 90 percent of cement kiln LVM test condition
data are currently achieving this emissions level.
Finally, as discussed for SVMs, EPA is continuing to investigate
the appropriate structure of metals standards (e.g., retain the
volatility groups or establish individual metals standards). The Agency
analyzed individual As, Be, and Cr (hexavalent) data and established
individual metal floor levels consistent with the engineering
evaluation and data analysis method. Where PM measurements are below
0.030 gr/dscf, the result would be: As 10 g/dscm, Be 1.1
g/dscm, and Cr (hexavalent) 4.6 g/dscm.
The Agency is concerned that some of the potential floor standards
for some individual metals (e.g., Be, Cr (hexavalent)) may be present
at levels approaching practical quantitation limits (PQLs). PQLs are
the lowest level of quantification that the Agency believes a competent
analytical laboratory can be expected to reliably achieve. The Agency
will investigate whether this issue may need to be addressed in the
development of any individual metals standards that may be considered
for the final rulemaking. We invite comment on the issue of PQLs and
LVM BTF standards.
b. BTF considerations for existing sources. In the NPRM, the Agency
considered a BTF standard for LVMs based on improved PM control below
0.030 gr/dscf. However, the Agency concluded that a BTF LVM standard
would not be cost-effective.
As discussed for PM, a reduced PM emissions level based on improved
PM control could be considered in evaluating a potential BTF standard
(taking into consideration corresponding BTF reductions in LVMs and
SVMs) for existing CKs. Because both the PM and LVM floor levels
presented today would be similar to the proposed floor, a BTF standard
for either LVMs or individual As, Be, and Cr (hexavalent) standards
based on improved PM control would likely raise

[[Page 24230]]

significant cost-effectiveness concerns and may not ultimately be
appropriate.
c. MACT floor for new sources. At proposal, the Agency defined
floor control, based on the best performing source, as a fabric filter
with an air-to-cloth ratio less than 2.3 acfm/ft² and a HW
MTEC of 25,000 g/dscm. The proposed LVM floor level for new
CKs was 44 g/dscm.
Based upon our re-evaluation of the database, the floor control and
emission level discussed above for existing sources for LVMs would also
appear to be appropriate for new sources. MACT floor control is a well-
designed and properly operated PM control device (i.e., fabric filter,
ESP) achieving the PM floor level of 0.030 gr/dscf. The Agency's
evaluation of the LVM data results in a MACT floor of 63 g/
dscm.
Finally, individual metal floor levels for new sources are
identical to those for existing sources. Thus, the standards would be:
As 10 g/dscm, Be 1.1 g/dscm, and Cr (hexavalent) 4.6
g/dscm.
d. BTF considerations for new sources. In the NPRM, the Agency
considered a LVM BTF level, but determined that a BTF standard would
not be cost-effective.
As discussed for existing sources, the Agency considered a more
stringent PM emissions level for improved control of PM, SVM and LVM
emissions for new CKs. Because both the alternative PM and LVM floor
levels presented today are lower than the proposed floors, a BTF
standard for either LVMs or individual As, Be, or Cr (hexavalent)
standards based on improved PM control may be inappropriate in light of
the cost-effectiveness concerns inherent in this scenario.
7. Hydrochloric Acid and Chlorine (HCl/Cl2). a. MACT
floor for existing sources. At proposal, the Agency identified floor
control for total chlorine (i.e., HCl + Cl2) as feedrate
control of chlorine in the hazardous waste at an MTEC not to exceed 1.6
g/dscm, and proposed a floor standard of 630 ppmv. When we evaluated
the revised database prior to today's notice, we used a data analysis
method similar to that used at proposal. The floor control would be
defined the same way as proposed, but the floor standard would be 120
ppmv. This standard should be readily achievable given that 93 percent
of the test conditions in the revised database are meeting that level.
We used the following data analysis steps for both the proposed
standard and today's alternative standard: (1) Rank emissions from
lowest to highest; (2) define as floor control the highest hazardous
waste chlorine MTEC for the 6 percent of sources \35\ with the lowest
emissions; and (3) define as the floor standard the highest test
condition average emissions of any test condition operated at or below
the floor MTEC (i.e., the expanded universe). We then refined the data
analysis method in two respects based on an engineering evaluation of
the revised database: (1) We did not add a computed emissions
variability factor \36\; and (2) several test conditions were deleted
from the expanded universe where an engineering evaluation revealed
that SREs were significantly worse than the majority of other SREs.
---------------------------------------------------------------------------

\35\ Or where we had data from fewer than 30 sources, the three
sources with the lowest emissions (i.e., 3 represents the median of
the five best performing sources).
\36\ See previous discussion in the text. As we discussed at
proposal (61 FR at 17396), the computed variability factor for this
standard resulted in a standard that did not comport with
engineering information on the APCDs at issue, engineering
experience on facility performance within this source category, or
the emissions database.
---------------------------------------------------------------------------

In the case of total chlorine emissions for CKs, it appears not to
be appropriate to use a breakpoint analysis to screen from the expanded
universe sources that are not achieving an appropriate removal
efficiency. This is because total chlorine is removed incidentally by
reactions with the alkaline raw materials (e.g., limestone). Thus, it
is difficult to reason that poor SRE is caused by poor design,
operation, or maintenance of the control system. Nonetheless, we
believe it is still appropriate to screen out clearly anomalous SREs
because they are likely indicative of an incorrect MTEC value or
emission measurement. An incorrect value for either could affect the
floor standard.\37\
---------------------------------------------------------------------------

\37\ The floor standard without screening the anomalous SREs
would have been 160 ppmv.
---------------------------------------------------------------------------

b. BTF considerations for existing sources. At proposal, the Agency
defined BTF control as wet scrubbing with a 99 percent removal
efficiency, but determined that a BTF standard would not be cost-
effective. Given that the alternative floor level presented today would
be substantially lower than the proposed floor, a BTF standard would be
less cost-effective. Thus, we believe that our final analysis is likely
to conclude that a BTF standard would not be warranted.
c. MACT floor for new sources. At proposal, the Agency defined
floor control for new sources as hazardous waste feedrate control for
chlorine at an MTEC of 1.6 g/dscm or less. The proposed floor standard
was 630 ppmv, the same as the floor standard for existing sources.
Given that the alternative data analysis method discussed above for
existing sources did not change the expanded universe, except to screen
out test conditions with anomalous SREs, MACT floor control and the
floor emission level would be the same as for existing sources:
hazardous waste feedrate control for chlorine at an MTEC of 1.6 g/dscm
or less, resulting in a floor standard of 120 ppmv (i.e., after
screening out test conditions with anomalous SREs).
d. BTF considerations for new sources. The Agency proposed a BTF
standard for new sources of 67 ppmv based on wet scrubbing. Given that
under the revised data analysis method discussed today the floor
standard would be much lower than proposed, the Agency believes that
the economic impact analysis being conducted in support of the final
rule is likely to raise significant concerns about cost-effectiveness.
In that event, the Agency would promulgate the 120 ppmv floor standard
for new sources.
8. Carbon Monoxide (CO). The Agency proposed the same MACT floor
standards for CO for existing and new CKs, and determined that BTF
controls would not be cost-effective. Floor control was defined for
kilns with by-pass ducts as operation under good combustion practices
and the standard was 100 ppmv, HRA, measured in the by-pass duct. For
kilns without a by-pass duct (i.e., long wet and dry kilns), no CO
standard was proposed given that CO levels in the main stack would not
be an indicator of combustion efficiency. This is because CO can be
generated by process chemistry (i.e., dissociation of CO2 to
form CO) and evolution from trace organics in the raw material
feedstocks, as well as from combustion of fuels.
The Agency continues to believe that the proposed CO standard for
kilns equipped with a by-pass duct would be appropriate. However, under
one option being considered for limiting CO (and HC) emissions, kilns
without a by-pass duct would also be required to comply with a CO limit
based on the level achieved during the performance test demonstrating
compliance with the HC limit. See discussion in Part Two, Section II.C.
Finally, the Agency continues to believe that a BTF standard for CO
based on better combustion practices is likely to raise significant
cost-effectiveness considerations.
9. Hydrocarbons (HC). The Agency proposed the same MACT floor
standards for HC for existing and new CKs, and determined that BTF
controls would not be cost-effective. Floor

[[Page 24231]]

control was defined for kilns with by-pass ducts as operation under
good combustion practices and the standard was 6.7 ppmv, based on an
hourly rolling average (HRA and measured in the by-pass duct. For kilns
without a by-pass duct (i.e., long wet and dry kilns), floor control
was defined as good combustion practices and use of raw materials with
relatively low organic content, and the standard was 20 ppmv, HRA,
measured in the main stack.
In evaluating the revised database for today's notice, the 20 ppmv
standard still appears to be appropriate for the main stack of long
kilns ³⁸. When considering by-pass kilns, however, the
revised database still lacks HC emissions data for the only two CKs
currently burning hazardous waste in units equipped with by-pass ducts.
These two sources are complying with the BIF rules by documenting that
CO levels are below 100 ppmv, HRA. ³⁹ Under one attractive
option for compliance with the CO and HC standards (i.e., sources would
have the option of complying with either the CO or HC standard; see
discussion in Part Two, Section II.C), we would expect that these two
sources would continue to comply with the CO limit. Thus, it may not be
necessary to establish a HC limit for them. However, given that it may
be prudent to establish a HC limit for these by-pass kilns, we would
transfer the good combustion practices-based HC standard for
incinerators--10 ppmv, HRA--to these kilns. This is appropriate
because: (1) Good combustion practices is floor control for CO and HC
for these kilns as well as for incinerators; and (2) given that the
good combustion practices-based CO standard is the same for
incinerators and by-pass kilns, the good combustion practices-based HC
standard should also be the same.
---------------------------------------------------------------------------

\38\ The Agency did not propose a HC standard for the main
stack of a preheater or preheater/precalciner kiln. See FR at 17397-
8. The Agency is currently developing MACT standards for non-waste
burning cement kilns, however. Any standards that the Agency may
propose that are applicable to the main stack of a preheater or
preheater/precalciner non-waste burning kiln may also be appropriate
for the main stack of such hazardous waste burning kilns.
\39\ The two kilns operating with by-pass ducts are Medusa's
facility in Demopolis, AL, and Lone Star's facility in Cape
Girardeau, MO. We note that Holnam has a long wet kiln in
Clarksville, MO that has been retrofitted with a mid-kiln sampling
port for purposes of monitoring CO in compliance with the BIF rule.
That monitoring approach would be acceptable under the MACT rule as
well.
---------------------------------------------------------------------------

As discussed at proposal, the Agency continues to be concerned
about cost-effectiveness considerations related to BTF controls for HC
based on operating under better combustion practices.
G. Re-Evaluation of Proposed MACT Standards for Lightweight Aggregate
Kilns
We discuss in this section the basis for the revised standards for
LWAKs that could result from applying various engineering evaluation
and data analysis methods to the revised emissions database
⁴⁰. A comparison of the proposed and potentially revised
standards for existing and new sources is presented in the table below:
---------------------------------------------------------------------------

\40\ Additional details of the engineering and data analysis
evaluations performed on the revised emissions database can be found
in the Agency's background document: USEPA, ``Draft Technical
Support Document for HWC MACT Standards (NODA), Volume I: MACT
Evaluations Based on Revised Database'', April 1997.

Table II.G:--Revised Standards for Existing and New LWAKs \1\
----------------------------------------------------------------------------------------------------------------
Existing sources New sources
-------------------------------------------------------
HAP or HAP surrogate Proposed Revised Proposed Revised
standard standard standard standard
----------------------------------------------------------------------------------------------------------------
D/F (ng TEQ/dscm)....................................... 0.20 0.20 0.20 0.20
Hg (g/dscm).................................... 72 47 72 47
PM (gr/dscf)............................................ 0.030 0.022 0.030 0.022
HCl/Cl2 (ppmv).......................................... 450 130 62 43
CO (ppmv)............................................... 100 100 100 100
HC (ppmv)............................................... 14 10 14 10
SVM (g/dscm)................................... 12 76 5.2 76
LVM (g/dscm)................................... 340 37 55 37
----------------------------------------------------------------------------------------------------------------
\1\ All emission levels are corrected to 7% O2.

1. Dioxins and Furans (D/F). a. MACT floor for existing sources. At
proposal, the Agency had D/F emissions for only one LWAK and therefore
pooled that LWAK data point with D/F data for CKs to identify MACT
standards. Consequently, floor control and the floor emission level for
LWAKs were the same as for CKs. The proposed floor control was
``temperature control at the inlet to the fabric filter ⁴¹
at 418 deg.F'', and the proposed floor emission level was ``0.20 ng
TEQ/dscm, or temperature at the inlet to the fabric filter not to
exceed 418 deg.F''. The Agency reasoned that pooling D/F data for
LWAKs and CKs could be appropriate because both types of devices are
designed and operated similarly with respect to factors that can affect
surface-catalyzed D/F formation. Both LWAKs and CKs have high PM inlet
loadings comprised primarily of entrained raw material and both are
equipped with fabric filters that operate within the same temperature
range.
---------------------------------------------------------------------------

\41\ All LWAKs currently burning hazardous waste are equipped
with fabric filters.
---------------------------------------------------------------------------

Commenters on the proposed rule, however, argued that pooling LWAK
and CK D/F data was inappropriate for purposes of establishing MACT
standards for LWAKs. Since proposal, the Agency has obtained D/F
emissions data from two additional LWAK facilities. These data are
included in the revised emissions database and are used to identify the
alternative standards presented here.
Based upon evaluation of the revised LWAK D/F database, our
engineering evaluation of the data and other information on LWAK
performance suggests the floor control can be specified as
``temperature control at the inlet to the fabric filter at 400
deg.F''. This would result 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'.⁴² Given that the entire
revised database also comprises the expanded universe (all sources
using floor control) the highest single run for the test condition

[[Page 24232]]

with the highest run average would be a reasonable floor level from an
engineering perspective. (Note that if this were a large data set, the
floor level could be identified simply as the highest test condition
average.) This floor level is more than 40 percent higher than the
highest test condition average (because of substantial variability
among the runs for that test condition), and thus appears to be a level
that LWAKs should be able to meet routinely using floor control.
---------------------------------------------------------------------------

\42\ The standard would be expressed in the form of a TEQ level
combined with a maximum temperature at the PM control device. This
form of the standard is consistent with the revised data and would
result in somewhat lower emissions (i.e., because without the TEQ
limit, some sources could exceed that TEQ level at the specified
temperature). Thus, expressing the standard in this form better
achieves the statutory mandate to establish standards that provide
the maximum degree of reduction that is achievable in practice.
---------------------------------------------------------------------------

As discussed for CKs, temperature control to 400 deg.F or less 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 D/F formation is 450-750 deg.F; and (2) below 350
deg.F, kiln gas can fall below the dew point which can increase
corrosion in fabric filters and reduce performance of the control
device. In addition, more than three LWAKs in the revised database were
operated at temperatures of 400 deg.F or less (even though we do not
have D/F emissions data for them). Thus, this temperature level appears
to be readily achievable.
Although only two of the three LWAKs for which we have D/F
emissions data operated the fabric filter at 400 deg.F or lower (the
third operated at 417 deg.F), we have fabric filter operating data for
other LWAKs when performing emissions testing for other HAPs that
document fabric filter operations at 400 deg.F or lower. The LWAK
whose fabric filter was operated at 417 deg.F had lower D/F emissions
than a kiln whose fabric filter was operated at 400 deg.F. Thus, even
though our engineering evaluation did not explicitly include the LWAK
whose fabric filter operated at 417 deg.F, defining MACT floor control
as ``temperature control at the inlet to the fabric filter at 400
deg.F'' did not result in a lower MACT floor emission level (i.e.,
lower than 4.1 ng TEQ/dscm). Rather, doing so ensures that LWAKs will
be operating at floor levels consistent with sound operational
practices for controlling D/F.
b. BTF considerations for existing sources. The Agency proposed a
BTF standard of 0.20 ng TEQ/dscm based on ACI operated at a temperature
of 400 deg.F.
Upon evaluation of the revised LWAK D/F database, LWAKs appear to
be able to achieve a 0.20 ng TEQ/dscm standard simply by rapidly
quenching combustion gases at the exit of the kiln to 400
deg.F, and insulating the duct-work leading to the fabric filter to
maintain gas temperatures and avoid dew point problems. Although the
data are not conclusive, and further testing is warranted to confirm
this approach, our engineering evaluation of all available information
indicates that this approach should be feasible.⁴³ If this
approach proves to be less effective than anticipated, then ACI can be
used to achieve the BTF standard.
---------------------------------------------------------------------------

\43\ See USEPA, ``Draft Technical Support Document for HWC MACT
Standards (NODA), Volume I: MACT Evaluations Based on Revised
Database'', April 1997.
---------------------------------------------------------------------------

We continue to believe that this BTF standard is appropriate given
the concerns the Agency has expressed about the risks posed by D/F
emissions. See discussion regarding a D/F BTF standard for CKs at 61 FR
17392. Further, a BTF standard of 0.20 ng TEQ/dscm would preclude the
need to provide further controls under RCRA authority.
c. MACT floor for new sources. At proposal, the BTF considerations
for new LWAKs were the same as for new CKs, and the proposed standards
were the same.
Upon evaluation of the revised LWAK D/F database, the floor control
and emission level discussed above for existing sources would also
appear to be appropriate for new sources (i.e., ``temperature control
at the inlet to the fabric filter at 400 deg.F'' corresponding to an
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 indicates that the best controlled
source is one that is controlling temperature control at the inlet to
the fabric filter at 400 deg.F.
d. BTF considerations for new sources. The Agency proposed ACI as
BTF control and a BTF standard of 0.20 ng TEQ/dscm. We continue to
believe that this BTF standard is appropriate for new sources for the
same reasons discussed above in the context of existing sources. Note
that BTF control, as for existing sources, would be defined as rapid
quench of kiln gas to 400 deg.F combined with duct
insulation, as required, or ACI operated at 400 deg.F.
2. Mercury (Hg) a. MACT Floor for existing sources. At proposal,
the Agency identified floor control as hazardous waste feedrate control
not to exceed an MTEC of 17 g/dscm. EPA proposed a floor
standard of 72 g/dscm.
All LWAKs employ fabric filters and one source uses a fabric filter
and venturi scrubber to control mercury. However, since Hg is generally
in the vapor form in and downstream of the combustion chamber,
including the air pollution control device, fabric filters alone do not
achieve good mercury control. Mercury emissions from LWAKs are
currently controlled under the BIF rule, which establishes limits on
the maximum feedrate of Hg in total feedstreams (e.g., hazardous waste,
raw materials). Thus, MACT is based on hazardous waste feed control.
Review of the updated Hg data in the revised database indicate that
LWAKs did not conduct Hg spiking of the hazardous wastes with the
exception of one facility, and thus the Hg content in the wastes during
testing is likely representative of typical operations. The data from
this testing also show that raw materials can represent a significant
source Hg input to the kiln system. Since the best performing sources,
measured by Hg emissions, do not employ a dedicated device capable of
Hg control, the Agency believes that the Hg data are essentially
``normal'' even though generated during worst case compliance testing
conditions for other parameters.
To evaluate these revised data for the purpose of determining a
MACT floor, the Agency used the following data analysis steps: (1) Rank
Hg emissions from lowest to highest; (2) conduct a breakpoint analysis
on the ranked Hg emissions data, and (3) establish the floor standard
equal to the test condition average of the breakpoint source. The
breakpoint analysis reflects an engineering evaluation of the data and
ensures that the one source that spiked elevated quantities of Hg did
not drive the floor level upward to levels higher than the
preponderance of this ``normal'' data indicates is routinely
achievable. The Agency's analysis results in a MACT floor level of 47
g/dscm. The revised database indicates that approximately 75
percent of LWAKs are achieving this floor level.
b. BTF considerations for existing sources. The Agency originally
considered a BTF standard based on flue gas temperature reduction to
400 deg.F or less followed by ACI, but determined that a BTF level
would not be warranted.
EPA continues to believe that flue gas temperature reduction to 400
deg.F followed by ACI is the appropriate BTF control option for
improved Hg control at LWAKs. As discussed above for existing CKs, we
have assumed an ACI effectiveness of 60 percent in identifying BTF
levels for LWAKs for the purposes of today's analysis. Thus, the BTF
standard is 15 g/dscm which is based on a ACI efficiency of 60
percent applied to the floor level of 33 g/dscm. Going to a
BTF standard of 15 g/dscm for mercury is consistent with the
range examined in the proposal.

[[Page 24233]]

However, at proposal, significant cost-effectiveness issues were raised
(and commented extensively on). It is likely that those same issues
would arise here with respect to a BTF standard of 15 g/dscm.
c. MACT floor for new sources. At proposal, the Agency identified
floor control as hazardous waste feedrate control not to exceed an MTEC
of 17 g/dscm--the same as existing sources. Thus, EPA proposed
an identical floor standard of 72 g/dscm.
For the same reasons discussed for existing LWAKs, the Agency
believes that the most appropriate engineering evaluation and data
analysis method to identify the floor level is identical to the
analysis done for existing sources. Thus, the MACT Floor standard would
be 47 g/dscm for new LWAKs.
d. BTF considerations for new sources. The Agency considered a BTF
standard for new sources based on ACI, but determined that it would not
be cost-effective to adopt the BTF standard. The Agency continues to
consider the use of ACI as the BTF technology. In evaluating the
revised database, EPA has identified a level of 15 g/dscm as
the BTF standard for new sources based on ACI and flue gas temperature
reduction to 400 deg.F or less. This is based on a source achieving
the MACT new floor level of 33 g/dscm and then applying ACI
with a 60 percent removal efficiency. Again, in light of the reasons
identified for existing sources, the Agency has concerns as to whether
a BTF level based on ACI will ultimately be warranted for new LWAK
sources.
3. Particulate Matter (PM). a. MACT Floor for Existing Sources. At
proposal, EPA defined floor control as a fabric filter with an air-to-
cloth ratio of 2.8 acfm/ft \2\. The MACT floor was 0.049 gr/dscf.
In evaluating the revised database, we examined a refined
engineering evaluation and data analysis method to identify a MACT
floor. This evaluation was a four-step process: (1) Rank all PM
emissions data and identify the MACT floor controls used by the best
performing 6 percent of sources. (2) Develop the expanded universe to
include all sources employing MACT control, without further
characterizing MACT control (e.g., air-to-cloth ratio of the fabric
filter) as done in the proposal because we do not have sufficient data
on the detailed design, operating, and maintenance characteristics
related to test conditions in the revised database. Since all LWAKs use
fabric filters for PM control, all test condition data are included in
the expanded universe. (3) For each PM test condition, evaluate the
corresponding SVM SRE and screen out sources that have relatively poor
SREs (i.e., outliers above a breakpoint in the data array), which is an
indicator of poor design, operation, and maintenance characteristics of
the MACT controls at the source. (4) Identify the MACT floor equal to
the highest test condition average of all test conditions in the PM
expanded universe.
The Agency's evaluation of the LWAK PM data results in a MACT floor
of 0.022 gr/dscf. All LWAK test condition data are achieving 0.022 gr/
dscf.
LWAKs typically operate at higher stack oxygen concentrations
compared to other combustion systems due to the LWAK manufacturing
process (e.g., excess air is forced into the kiln to aid in the
expansion of the raw material into lightweight aggregate). Typical
stack oxygen concentrations range from 12 to 16 percent, while CKs, for
example, typically range from 3 to 8 percent. Since the standards are
expressed at 7 percent oxygen, the floor standard of 0.022 gr/dscf
would be equivalent to 0.014 gr/dscf at 12 percent oxygen and 0.008 gr/
dscf at 16 percent oxygen under the conditions that LWAKs typically
operate.
In the NPRM, the Agency proposed that sources maintain continuous
compliance with the PM standard through the use of a PM CEMS. A
decision whether to require LWAKs to install a PM CEMS will be made at
the completion of an on-going demonstration testing program to
determine if at least one PM CEMS can meet the proposed performance
specifications. Since the floor standard discussed above was based on
manual test method data, the Agency will re-evaluate at the completion
of the CEMS testing program whether these PM floor standards would be
appropriate in the event that the final rulemaking requires continuous
compliance with a PM CEMS. The Agency will notice the results and
conclusions of the demonstration test program in the docket for the HWC
rule.
b. BTF considerations for existing sources. In the NPRM, the Agency
proposed a BTF level of 0.030 gr/dscf and solicited comment on an
alternative BTF level of 0.015 gr/dscf based on improved PM control.
Based on the revised database, we can evaluate a reduced PM
emissions level lower than 0.022 gr/dscf as the BTF standard (in
conjunction with BTF reductions in SVMs and LVMs). This would require
an improved PM collection technology such as the use of more expensive
fabric filter bag material. Given that the alternative floor level
analysis presented today would be substantially lower than the proposed
floor and BTF levels, significant cost-effectiveness considerations
come into play and suggest that BTF levels may not ultimately prove to
be warranted.
c. MACT floor for new sources. At proposal, EPA defined floor
control for new sources as a fabric filter with an air-to-cloth ratio
of 1.5 acfm/ft \2\. The MACT floor was 0.054 gr/dscf.
Based upon evaluation of the revised database, the floor control
and emission level discussed above for existing sources would also
appear to be appropriate for new sources. Therefore, MACT floor control
is a well-designed and properly operated fabric filter, and the MACT
floor for new LWAKs is 0.022 gr/dscf.
d. BTF considerations for new sources. In the NPRM, EPA proposed a
BTF standard of 0.030 gr/dscf based on improved PM control, which was
consistent with existing sources.
Today, as discussed above for existing source BTF considerations
and based upon examining the revised database in light of the findings
at proposal, a BTF standard for new sources beyond 0.022 gr/dscf (and
corresponding BTF reductions for SVMs and LVMs) would not appear to be
cost-effective.
4. Semivolatile Metals (SVM) (cadmium and lead). a. MACT floor for
existing sources. At proposal, EPA defined floor control as either (1)
a fabric filter with an air-to-cloth ratio of 1.5 acfm/ft \2\ with a
hazardous waste (HW) MTEC less than 270,000 g/dscm, 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 HW MTEC less than 54,000
g/dscm. The proposed floor level was 12 g/dscm.
LWAKs use a combination of good PM control and limiting hazardous
waste feedrates to control SVM emissions. SVMs are controlled most
efficiently by technologies which are effective at capturing fine PM,
such as fabric filters which are employed by all LWAKs. EPA's revised
database shows that SVM emissions vary substantially from 3 to over
1600 g/dscm with 60 percent below 80 g/dscm and the
remaining 40 percent above 400 g/dscm.
The refined data analysis method used by EPA to evaluate and
identify a MACT floor would be based directly on the results from the
PM floor analyses discussed above. As mentioned there, 0.022 gr/dscf
would appear to represent the MACT floor for LWAKs based on good PM
control. Since SVMs are controlled, in part, by a well-designed and
operated PM control devices, it follows that sources achieving this PM

[[Page 24234]]

performance level should also be controlling SVMs emissions.
Therefore, in its refined SVM analyses of the revised database, the
Agency would first consider all SVM data when corresponding PM
measurements are below 0.022 gr/dscf. To identify the SVM floor from
these data, we identify either at the highest SVM test condition
average or the level that excludes sources achieving substantially
poorer SVM control than the majority of sources. It is most likely
appropriate to use the latter approach--excluding sources with
significantly poorer SVM performance--because their higher SVM
emissions may be the result of exceedingly high SVM feedrates or some
other factor which is not able to be discerned from the data available
to the Agency. An SVM emissions breakpoint analysis is the approach for
excluding these poorer performing test conditions.
Applying this evaluation technique to the revised LWAK SVM database
results in a MACT floor of 76 g/dscm. Approximately 62 percent
of LWAK SVM test condition data are currently achieving this emissions
level.
Finally, as discussed in an earlier section, a preliminary analysis
indicates that MACT standards may not be warranted for one HAP metal,
antimony. Since the number of metals being considered for MACT
standards may change, we are investigating the appropriate structure of
metals standards (e.g., retain the volatility groups or establish
individual metals standards). Using the refined method discussed above
for SVM, we analyzed the revised database with respect to Cd and Pb
data. The floor analysis corresponding to PM measurements below 0.022
gr/dscf would result in the following floor levels: Cd 53 g/
dscm, and Pb 67 g/dscm.
b. BTF considerations for existing sources. In the NPRM, the Agency
considered a BTF standard for SVMs based on improved PM control.
However, the Agency concluded that a BTF standard would not be cost-
effective given that the SVM floor level of 12 g/dscm alone
would result in an estimated 97 percent SVM reduction in emissions.
As discussed for PM BTF considerations, the Agency also re-
evaluated the possible appropriateness of using a reduced PM emissions
level based on improved PM control as a BTF standard (with
corresponding BTF reductions in SVMs and LVMs). Even though the
alternative SVM floor standard is higher than at proposal, our
preliminary judgement is that significant cost-effectiveness
considerations will be nonetheless encountered in a final analysis of
whether to establish a BTF standard for SVMs or for Pb or Cd
individually.
If, however, the revised risk assessment yet to be conducted would
show significant risk at a SVM floor standard of 76 g/dscm,
which would be the floor level resulting from application of the data
analysis method discussed above, the Agency will determine whether a
BTF standard based on control of SVM feedrate to levels below those at
the floor would be appropriate. This feedrate limitation would in turn
reduce SVM emissions. The BTF standard and the corresponding level of
feedrate control would be dictated by considerations of cost-
effectiveness and the need to establish more stringent RCRA-related
controls.
c. MACT floor for new sources. At proposal, EPA defined floor
control as a fabric filter with an air-to-cloth ratio of 1.5 acfm/ft
\2\ with a hazardous waste (HW) MTEC less than 270,000 g/dscm.
The proposed floor level was 5.2 g/dscm.
Upon evaluation of the revised database, EPA believes that the
floor control and emission level discussed above for existing sources
for SVMs would also be appropriate for new sources. In this event, MACT
floor control would be a well-designed, operated and maintained PM
control device (e.g., fabric filter) achieving the PM floor level of
0.022 gr/dscf. The Agency's evaluation of the SVM data results in a
MACT floor of 76 g/dscm.
Finally, based on the revised database, individual metal floor
levels for new sources are identical to those for existing sources.
Thus, individual Cd and Pb standards are 53 g/dscm for Cd and
67 g/dscm for Pb.
d. BTF considerations for new sources. In the NPRM, the Agency
considered a SVM BTF level, but determined that a BTF standard would
not be cost-effective.
As discussed for existing sources, the Agency considered a more
stringent PM emissions level for improved control of PM, SVM and LVM
emissions for new LWAKs in light of the revised database. Even though
the SVM floor standard is higher than at proposal, as discussed above,
cost-effectiveness issues are again raised and suggest that a BTF
standard for either SVMs or for Pb or Cd individually based on improved
PM control may likewise ultimately prove to be inappropriate.
5. Low Volatile Metals (LVM) (arsenic, beryllium, and chromium) a.
MACT Floor for Existing Sources. At proposal, EPA defined floor control
as a fabric filter with an air-to-cloth ratio of 1.8 acfm/ft \2\ with a
HW MTEC less than 46,000 g/dscm.
The proposed floor level was 340 g/dscm, which included
antimony.
LWAKs use a combination of good PM control and limiting hazardous
waste feedrates to control LVM emissions. LVMs are less likely to
vaporize at combustion temperatures and therefore partition primarily
to the residue or adsorb onto particles in the combustion gas. EPA's
database shows that LVM emissions vary from around 20 to 285
g/dscm.
The engineering evaluation data analysis method used by EPA to
evaluate the revised database and identify a MACT floor for LVMs is
also related directly to the PM floor analysis. As was determined in
the PM analysis, a floor of 0.022 gr/dscf represents MACT for LWAKs
based on good PM control. Considering all LVM data from sources
achieving a PM level 0.022 gr/dscf or better, EPA's evaluation of the
revised LWAK data results in a LVM floor of 37 g/dscm
(excluding sources above a breakpoint and therefore achieving
substantially poorer LVM emissions than the majority of sources).
Approximately 71 percent of LWAK LVM test condition data are currently
achieving this emissions level.
Finally, as discussed for SVMs, EPA is continuing to investigate
the appropriate structure of metals standards (e.g., retain the
volatility groups or establish individual metals standards). The Agency
analyzed individual As, Be, and Cr (hexavalent) data and established
individual metal floor levels consistent with the engineering
evaluation and data analysis method. Where PM measurements are below
0.022 gr/dscf, the result would be: As 22 g/dscm, Be 3
g/dscm, and Cr (hexavalent) 6.2 g/dscm.
The Agency is concerned that some of the potential floor standards
for some individual metals (e.g., Be, Cr (hexavalent)) may be present
at levels approaching practical quantitation limits (PQLs). PQLs are
the lowest level of quantification that the Agency believes a competent
analytical laboratory can be expected to reliably achieve. The Agency
will investigate whether this issue may need to be addressed in the
development of any individual metals standards that may be considered
for the final rulemaking. We invite comment on the issue of PQLs and
LVM BTF standards.
b. BTF considerations for existing sources. In the NPRM, the Agency
considered a BTF standard for LVMs based on improved PM control.
However, the Agency concluded that a

[[Page 24235]]

BTF standard would not be cost-effective.
As discussed for PM BTF considerations, the Agency also re-
evaluated the possible appropriateness of using a reduced PM emissions
level based on improved PM control as a BTF standard (with
corresponding BTF reductions in SVMs and LVMs). Considering that the
alternative LVM floor standard would be lower than at proposal, our
preliminary judgment is that significant cost-effectiveness
considerations will likely be encountered in a final analysis of
whether to establish a BTF standard for either LVM or for As, Be, or Cr
(hexavalent) individually.
c. MACT floor for new sources. At proposal, EPA defined floor
control as a fabric filter with an air-to-cloth ratio of 1.3 acfm/ft
\2\ with a hazardous waste (HW) MTEC less than 37,000 g/dscm.
The proposed floor level was 55 g/dscm.
Based upon our re-evaluation of the database, the floor control and
emission level discussed above for existing sources for LVMs would also
appear to be appropriate for new sources. MACT floor control is a well-
designed and properly operated PM control device (i.e., fabric filter)
achieving the PM floor level of 0.022 gr/dscf. The Agency's evaluation
of the LVM data would result in a MACT floor of 37 g/dscm.
Finally, individual metal floor levels for new sources are
identical to those for existing sources. Thus, the standards would be:
As 22 g/dscm, Be 3 g/dscm, and Cr (hexavalent) 6.2
g/dscm.
d. BTF considerations for new sources. In the NPRM, the Agency
considered a LVM BTF level, but determined that a BTF standard would
not be cost-effective.
As discussed for existing sources, the Agency considered a more
stringent PM emissions level for improved control of PM, SVM and LVM
emissions for new LWAKs. Because the alternative PM and LVM floor
levels presented today are lower and approximately equivalent,
respectively, than the proposed floors, a BTF standard for either LVMs
or individual As, Be, or Cr (hexavalent) standards based on improved PM
control may be inappropriate in light of the cost-effectiveness
concerns inherent in this scenario.
6. Hydrochloric Acid and Chlorine (HCl/Cl2) a. MACT
floor for existing sources. At proposal, the Agency identified floor
control for total chlorine as either: (1) Hazardous waste feedrate
control of chlorine to a MTEC of 1.5 g/dscm or less; or (2) venturi
scrubber with hazardous waste MTEC of 14 g/dscm or less. The proposed
floor emission level was 2100 ppmv.
Upon evaluation of the revised database, the data analysis method
used at proposal appears still to be appropriate and, consequently,
floor control would be defined virtually the same as at proposal.
However, EPA no longer thinks it appropriate to add a computed
emissions variability factor to the standard-setting test condition for
large data sets ⁴⁴. Thus, the floor emission level would be
1300 ppmv rather than 2100 ppmv.
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\44\ See discussion in Part Two, Section II.D.
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b. BTF considerations for existing sources. At proposal, the Agency
defined BTF control as wet or dry lime scrubbing with a control
efficiency of 90 percent and proposed a BTF standard of 450 ppmv.
The Agency continues to believe that wet or dry lime scrubbing can
achieve at least 90 percent removal of HCl/Cl2. Therefore, the revised
BTF standard would be 130 ppmv assuming that the requisite cost-
effectiveness information continues to suggest that a BTF standard is
warranted. The two LWAKs that are equipped with wet scrubbers achieved
emission levels below 45 ppmv.
c. MACT floor for new sources. At proposal, the Agency defined MACT
floor control for new sources as a venturi scrubber with a hazardous
waste MTEC of 14 g/dscm or less, and identified a floor level of 62
ppmv.
As for existing sources, the data analysis method used at proposal
for new sources is appropriate and, consequently, floor control for new
sources would be defined the same as at proposal. Excluding a computed
emissions variability, the floor emission level would be 43 ppmv rather
than 62 ppmv.
d. BTF considerations for new sources. The Agency did not propose a
BTF standard for new sources because the floor standard was based on
best available control technology: wet scrubbing. We have no new
information in the revised database that would indicate that this
conclusion at proposal should be revisited.
7. Carbon Monoxide (CO). The Agency proposed a MACT standard for CO
of 100 ppmv based on a hourly rolling average (HRA). We continue to
believe that this standard is appropriate for the reasons expressed in
the preamble to the proposal.
8. Hydrocarbons (HC). The Agency proposed a HC level of 14 ppmv
based on floor control using good combustion practices. Although we
continue to believe that floor control is good combustion practices,
our engineering evaluation of the revised database suggests that a
floor standard of 10 ppmv, HRA, may be more appropriate. The single
LWAK facility in the revised emissions database that could not achieve
a HC standard of 10 ppmv (perhaps because of trace organics in the raw
material) has stopped burning hazardous waste. Data from that facility
have been excluded in the revised analysis. Although the remaining
LWAKs appear to be able to meet a HC standard on the order of 6 ppmv,
it may be more appropriate to establish the standard at 10 ppmv. This
is because we are not aware of an engineering reason that LWAKs using
good combustion practices should be able to achieve lower HC emissions
than incinerators. Given that the incinerator HC standard would be 10
ppmv, that standard also appears to be appropriate for LWAKs.

Part Three: Implementation

I. Compliance Date Considerations

The Agency proposed that all sources subject to the final rule be
in compliance with the final standards three years following the
effective date of the rule (61 FR 17416). The proposed compliance
period is consistent with the CAA, which defines the maximum compliance
period for sources regulated under the statute as three years, with the
possibility of a one-year extension for those sources that adequately
demonstrate a need for additional time for the installation of emission
controls. The Agency proposed the maximum compliance period allowed by
the Act because this rule will likely require the majority of units,
currently operating under RCRA regulations, to undergo substantial
modifications to come into compliance with the potentially more
stringent final MACT standards.
The general provisions of 40 CFR Part 63 do not require a
demonstration of compliance until 240 days following the compliance
date. This 240 day period between the compliance date and the
demonstration of compliance is clearly not appropriate for HWCs because
these devices are presently regulated under RCRA via enforceable
operating limits, and in this interim period the enforceable operating
limits would be undefined (61 FR 17415).
Therefore, to provide consistency with the currently-applicable
RCRA regulatory compliance scheme, the Agency departed from the general
requirements applicable to MACT sources and proposed a revised
definition of compliance date. The proposed definition of compliance
date would require sources to complete installation of controls and to

[[Page 24236]]

successfully complete performance testing and certify compliance within
the three-year compliance period, not by a date 240 days after the
three-year compliance period. Id. In addition to the revised definition
of compliance date, the Agency also proposed a number of extra
consequences for HWC sources that are not in compliance by the
compliance date: (1) Immediate termination of waste-burning activities;
(2) loss of RCRA permit or interim status; (3) a requirement to obtain
a new RCRA permit; and (4) compliance with MACT standards for new
sources.
In response to the proposal, the Agency received comments
suggesting the three-year compliance period would be impossible to meet
due to a number of competing factors, and that more time would be
necessary to comply with the rule. These factors included permit
modification, installation of controls, and documentation of
compliance. Furthermore, commenters expressed serious concerns about
combining these factors with the consequences of missing the compliance
date. Industry commented that under this proposed approach facilities
engaged in legitimate efforts to comply with the standards would be
forced to terminate waste-burning activities, and be subjected to
burdensome consequences that are unnecessary to protect the environment
or ensure the public's safety.
However, EPA has become persuaded by commenters concerns regarding
the ability of HWC sources in particular to comply with the proposed
standards by the compliance date. Sources will have to modify their
RCRA permits. Further, some sources may choose to pursue waste
minimization strategies. For these reasons, the Agency is considering
certain actions that may be finalized in advance of the final HWC rule
such as, the streamlined permit modification procedures discussed at
17455 in the proposal; as well as, the waste minimization option for
extension of the compliance date to allow for the application of waste
minimization controls to meet the final standards discussed at 17417.
The streamlined permit modification procedures would reduce the
administrative requirements and time necessary to begin modification
procedures required to comply with the final standards. The waste
minimization compliance date extension option, which provides an
additional avenue for facilities to request an extension of the
compliance date, would afford facilities that choose to institute waste
minimization measures an additional year to complete these actions.
However, even with the special provisions under consideration,
sources may require the full amount of time allowed under the CAA to
comply. Therefore, the Agency is also considering a revised
implementation scheme that will allow for a simplified approach
consistent with the implementation of general CAA-MACT rules. This
approach would provide both additional relief to sources complying with
the final rule, and information regarding a source's compliance status
on the compliance date for the Agency. The specifics of this new option
are explained in greater detail in the following paragraphs. Comments
are requested on this new approach to implementing the HWC MACT
standards.
A. Definition of Compliance Date
Today, the Agency is considering a revision to the proposed
definition of compliance date. Under this revised approach, HWC sources
would follow the CAA-MACT schedule for demonstration of compliance,
through MACT performance testing and submission of test results,
contained in Sec. 63.7. Under that section, affected sources must
conduct performance tests within 180 days following the compliance
date, and submit the results of the tests 60 days following the
completion of the performance test.⁴⁵ This CAA-based
approach responds to the comments questioning our revised definition of
compliance date and would achieve a more consistent implementation
framework. However, because the Agency is concerned about the
compliance status of affected sources on the compliance date, the
Agency also seeks comment on provisions to enhance the general
requirements for HWCs with a requirement for the submission of a
``precertification of compliance'' in the final rule. A
precertification of compliance would require facilities to precertify
their compliance status on the compliance date. The details of the
precertification of compliance are described in greater detail in the
following paragraphs.
---------------------------------------------------------------------------

\45\ In the HWC proposed rule, however, the Agency allowed
sources 90 days to submit test results because D/F analyses can
require more time than traditional MACT analyses. We continue to
believe that this 90-day allowance is appropriate.
---------------------------------------------------------------------------

B. Pre-Certification of Compliance
Today the EPA is seeking comment on an option which would require
sources to submit a notification to regulatory agencies that details
the operating limits a unit will be operated under in the interim
period following the compliance date but before the results of the
initial comprehensive performance test are submitted. This
notification, the precertification of compliance, would include all of
the information necessary to determine the compliance status of an
affected source (e.g., automatic waste feed cutoff limits, feedrate
limits, emission control device operating limits, etc.) during the 240
day period after the compliance date. At a minimum, the facility would
be required to establish operating limits on all of the parameters
identified in the proposed monitoring requirements found in table V.2.1
at 17419 of the proposed rule. This approach is appropriate because
these facilities are already regulated under RCRA. There should not be
any ambiguity for these facilities in terms of being between regulatory
regimes at any point in time.
The operating limits in the precertification of compliance would be
enforceable limits.⁴⁶ However, if following the initial
comprehensive performance test, the facility's precertification of
compliance designated operating limits are found to have been
inadequate to ensure compliance with the MACT standards, the facility
will not be deemed out of compliance with the MACT emissions standards.
EPA invites comment on this approach, and specifically invites comment
on the necessity of establishing operating limits on the entire set of
parameters identified in table V.2.1.
---------------------------------------------------------------------------

\46\ The Agency notes that under this scheme facilities are
still subject to the RCRA emission limitations, and the associated
operating limits and enforcement actions until removal of the air
emission limitations from the RCRA permit. However, because on the
compliance date all facilities must be compliance with the emission
standards of the final MACT rule, the Pre-COC operating limits,
which are expected to be more stringent than current RCRA emission
standards, take precedence over the RCRA permit limits except where
the RCRA permit limits are based on a more stringent standard
adopted under the Omnibus provisions of RCRA section 3005.
Furthermore, EPA notes that compliance with Pre-COC operating limits
that are based on standards that are more stringent than RCRA
emission standards assures compliance with the RCRA based emission
standards.
---------------------------------------------------------------------------

C. Consequences of Non-compliance
As mentioned earlier, the Agency proposed a number of serious
consequences that would befall a source that misses the compliance date
(61 FR 17416). The Agency proposed these consequences to provide an
incentive for affected sources to move swiftly to comply with the final
standards. In response to the proposal, through written comments from
industry and during round table discussions with

[[Page 24237]]

affected parties, the Agency received information suggesting that
imposition of these consequences through regulatory language was
unnecessary. Consequently, the Agency is considering deleting those
specific consequences from the regulatory language and relying on the
regulating agency's policy regarding enforcement response to govern the
type of enforcement response at a facility that fails to meet the
compliance deadline.
Upon review of this enforcement process, the Agency is presently
inclined to apply the normal CAA enforcement procedures to non-
compliant sources in the final rule for hazardous waste combustors.

II. Compliance Requirements

In this section, we discuss several compliance issues: (1)
Compliance with carbon monoxide (CO) and/or HC emission standards; (2)
compliance with a startup, shutdown, and malfunction plan when not
burning hazardous waste; (3) metals extrapolation and interpolation
considerations; (4) site-specific variances for cement kilns and LWAKs
because of inability to meet the standards solely due to metals or
chlorine in raw materials; and (5) emissions averaging for cement kilns
with unique design or operating features.
A. Compliance With CO and/or HC Emission Standards
The Agency proposed MACT emission standards for both CO and HC for
incinerators and LWAKs as surrogates to control emissions of organic
HAPs. Cement kilns would be required to comply with either a CO or HC
standard because of raw material considerations. See 61 FR at 17375-6.
The Agency explained that relying on only CO or HC alone appeared to
have drawbacks, and thus proposed that incinerators and LWAKs comply
with emissions standards for both. Nonetheless, the Agency acknowledged
that requiring compliance with standards for both CO and HC may be
unnecessarily redundant, and requested comment on the following
alternative approaches: (1) Giving sources the option of complying with
either CO or HC; or (2) establishing a MACT standard for either CO or
HC, but not both.
Although the Agency is continuing to evaluate comments and options
\47\ on how to limit CO and/or HC to control organic HAPs, we invite
comment on an additional feature of the first option whereby a source
can elect to comply with either the CO or HC standard. Under this
approach, a source that elects to comply with the CO standard (rather
than the HC standard) would be required to document during the
performance test compliance with the HC limit. This is necessary
because we have some (limited) data that show a source can have HC
levels exceeding the standard discussed in today's notice while meeting
the CO limit. Even though the vast majority of the data indicate that
HC will be low when CO levels are low, a requirement to confirm this
relationship on a site-specific basis may be warranted.
---------------------------------------------------------------------------

\47\ We are also evaluating another option whereby compliance
with the HC limit would be required, and a site-specific CO limit
(but not lower than 100 ppmv, the proposed MACT standard) would also
be established. This option would provide assurance that HC
emissions are within allowable levels, and by also limiting CO, it
would give the operator advance notice of a potential increase in HC
levels, thus helping to avoid an exceedance of the HC standard.
---------------------------------------------------------------------------

To confirm the relationship during the performance test, the source
would use a portable HC monitor to document that HC levels are below
the MACT standard. This is not expected to be a burdensome test.
Further, however, to ensure that the CO/HC relationship is maintained
over the range of operating conditions that the facility may ultimately
employ, we are considering whether to require the source to establish
limits on key operating parameters than can affect combustion
efficiency (and thus HC emissions). The limits would be established
based on parameter values observed while demonstrating the CO/HC
relationship during the performance test.
We specifically request comment on which key parameters should be
limited to ensure that the CO/HC relationship is maintained. Further,
we request comment on whether these key parameters should be identified
on a national basis or a site-specific basis during review of the
performance test protocol. In providing comment, note that the Agency
has already proposed to establish site-specific limits on several
combustion-related parameters to ensure compliance with the D/F
emission standard (e.g., minimum combustion chamber temperature;
maximum waste feedrate; and for batch fed units, maximum batch size and
feeding frequency, and minimum oxygen concentration in the combustion
gas). In addition, note that it may be appropriate to identify as key
parameters (for purposes of ensuring that the CO/HC relationship is
maintained) those parameters for which limits are currently established
during destruction and removal efficiency (DRE) testing, including: (1)
Minimum combustion temperature at each combustion chamber or feed
location; (2) minimum combustion gas residence time (i.e., maximum
combustion gas velocity, or appropriate surrogate); and (3) minimum
combustion gas oxygen concentration. If the Agency determines that DRE
testing is not necessary for some types of sources as discussed in
Section III below, testing to document the CO/HC relationship would be
used to establish limits on these heretofore DRE-limited parameters.
B. Startup, Shutdown, and Malfunction Plans
The Agency proposed that startup, shutdown and malfunction plans
are not necessary for hazardous waste combustion sources because the
allowances that such plans provide are not appropriate for hazardous
waste combustors (61 FR 17449). Specifically, the Agency stated that
EPA did not need information regarding how quickly a source is able to
correct a malfunction to come back into compliance with the standards
because affected sources cannot burn waste unless the source is in
compliance with all applicable standards.
However, in comments, the Agency was informed of a few situations
in which it is appropriate for sources to comply with a startup,
shutdown, and malfunction plan. These situations include those in which
sources temporarily stop burning hazardous waste but intend to resume
burning hazardous waste in the near future. The examples presented to
the Agency involve production units (i.e., cement kilns, LWAKs, and
possibly on-site incinerators equipped with waste heat boilers to
generate steam or heat at a chemical production facility) that must
continue operations following waste feed cutoff to maintain production
at the facility. Also, commenters cited temporary shutdowns necessary
for planned maintenance to be performed on the unit.
In light of these comments, the Agency is rethinking its proposed
approach and requests comment on a requirement for sources to comply
with the provisions listed in Sec. 63.7 regarding startup, shutdown and
malfunction plans, including the reporting requirements of
Sec. 63.10(d)(5)(I). These provisions would apply at HWCs when waste is
not being fed or does not remain in the combustor, excluding automatic
waste feed cutoff events.
Sources would be subject to the standards at all times, and the
malfunction plan would only apply during times when the source is
either temporarily not burning waste or when

[[Page 24238]]

waste no longer remains in the combustor. For example, if a source is
temporarily not burning waste and a malfunction occurs that is followed
by an exceedance of an applicable standard, the source will not be in
violation as long as it is complying with the procedures outlined in
the malfunction plan. On the other hand, if a source is burning waste
and a malfunction occurs that necessitates an automatic waste feed
cutoff followed by an exceedence of a standard, the source would be in
violation regardless of whether the source is complying with the
malfunction plan.\48\
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\48\ This situation would be considered a violation unless the
source can document that the exceedance occurred after waste was no
longer in the combustor and the residuals of the waste combustion
process had been treated by the pollution control equipment.
---------------------------------------------------------------------------

Therefore, under this option, a source may develop a malfunction
plan that details the situations in which the source is intentionally
not feeding waste, or that details the situations when certain emission
control devices will not be in operation.
C. Metals Extrapolation and Interpolation Considerations
In the NPRM, the Agency discussed the operating conditions under
which a source will likely operate to demonstrate compliance with the
metals emission limits identified in the proposed rule (61 FR at 17428-
30). The Agency also acknowledged in the proposal that operators will
likely want to operate their units during comprehensive performance
tests close to the edge of the operating envelope so that they can
comply with the emission standards and still achieve the necessary
operational flexibility required by the facility. EPA further stated
that, to achieve a sufficient level of operational flexibility, sources
could be expected to engage in the spiking of metals into the waste
matrix, which is a practice that concerns the Agency. EPA's concern
extends to the overall metals loading to the environment (for example,
Hg and Pb), exposure of facility employees, and exposure of surrounding
community to higher than normal metals concentrations due to testing
procedures that are for the purposes of developing waste feedrate
limits and operational flexibility.
Therefore, the Agency has investigated approaches that may provide
a method to afford additional metals feedrate flexibility without the
need of high metals spiking (otherwise necessary to identify a metals
feedrate for an associated metals emission level).\49\ One promising
approach would use a statistical extrapolation methodology.\50\
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\49\ 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.
\50\ Extrapolations would be based on applying a conservative
``universal variability factor'' (UVF) multiplier to the test
condition average. The UVF is based on evaluating within-test
condition emissions variability for each metal in the Agency's trial
burn and BIF certification of compliance metal emissions database.
It represents (in log form) a ``residual'' level that 95 percent of
the residual population is below, where the residual is defined as
the difference between the log of the emission level for each test
condition run and the log of the test condition average. The UVF
would range from 3x to 5x depending on the volatility grouping for
the metal. Given the conservatism of the UVF, a less conservative
approach would be used (i.e., melding extrapolating using the UVF
with extrapolating from the highest run in a test condition) to
extrapolate to feedrate and emission levels close to levels actually
tested.
---------------------------------------------------------------------------

Under this approach a source would use the metal feedrates and
emission rates associated with a MACT performance test to extrapolate
to higher allowable feedrates and emission rates. The Agency believes
that the upward extrapolation procedure developed can conservatively be
used to allow for higher metals feedrate limits, but still ensure that
the facility is well within any applicable MACT (or RCRA) emissions
limit.\51\ Although downward interpolation (i.e., between the measured
feedrate and emission level and zero) was also investigated, the Agency
is concerned that downward interpolation may not be conservative
primarily because system removal efficiency decreases as metal feedrate
decreases. Thus, projected emissions at lower feedrates may in fact be
lower than actual emissions. Consequently, the Agency is not inclined
to allow downward interpolation.
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\51\ Under the extrapolation approach, sources would be required
to feed metals at no less than normal rates to narrow the amount of
extrapolation sought. Further, we expect that some spiking would be
desired to increase confidence in the measured feedrate levels that
will be used to project higher allowable feedrates (i.e., the errors
associated with sampling and analyzing heterogeneous wastestreams
can be minimized by spiking known quantities). However, the Agency
does not want sources to extrapolate to allowable feedrates that are
significantly higher than their historical range of feedrates (i.e.,
extrapolated feedrates should be limited close to the historical
levels that a source actually fed). This may work to limit the
practical utility of extrapolation.
---------------------------------------------------------------------------

The Agency expects that any extrapolation methodology would be
reviewed and approved by regulatory officials. Sources would request
approval to extrapolate feedrates as part of the performance test plan
that would be submitted at least 60 days prior to the test date. See
Sec. 63.7(b) and (c) and proposed Sec. 63.1208. The review would
consider in particular whether: (1) Performance test metal feedrates
were appropriate (e.g., whether feedrates were at least at normal
levels; depending on the heterogeneity of the waste, whether some level
of spiking would be appropriate; and whether the physical form and
species of spiked material is appropriate); and (2) whether the
requested, extrapolated feedrates were warranted considering historical
metal feedrate data. In addition, regulatory officials would review the
performance test results in making a finding of compliance required by
Sec. 63.6(f)(3) to ensure that emission test results have been
interpreted properly and that the extrapolation procedure is
appropriate for the source.
The Agency is discussing this approach with some hesitation because
facilities 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 facilities should be trying to minimize
metals feedrates. However, because the Agency remains concerned that
sources would otherwise continue to feed metals during compliance
testing at high levels,⁵² to it may be appropriate to
consider this extrapolation approach as a means to reduce unnecessary
emissions and costs incurred by facilities (and the health risk to
testing personnel) during performance tests.
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\52\ To achieve operational flexibility due to practical testing
and compliance restrictions.
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EPA invites comment on this extrapolation approach, and in
particular, as to whether the approach is adequately conservative and
practicable.
D. Consideration of Site-Specific Variances for Cement Kilns and LWAKs
The Cement Kiln Recycling Coalition (CKRC) has provided comments on
the proposed rule suggesting that two variance procedures be
incorporated in the final rule: (1) Waiver of the Hg, SVM, LVM, and/or
HCl/Cl2 standards when metals or chlorine in minerals and related
process materials cause the source to exceed the standard even though
the source is demonstrable using MACT control; and (2) waiver of the HC
standard for the main stack of a long kiln that does not monitor CO or
HC in the by-pass duct when organics desorbed solely from minerals and
related process materials cause the source to exceed the standard in
the main stack.

[[Page 24239]]

CKRC notes that the Conference Report for the Clean Air Amendments
of 1990 ⁵³ states that:

\53\ H.R. Rep. No. 101-952, at p.339, 101st Cong., 2d Sess.
(Oct. 26, 1990).
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For categories and subcategories of sources of hazardous air
pollutants engaged in mining, extraction, beneficiation, and
processing of nonferrous ores, concentrates, minerals, metals, and
related process materials, the Administrator shall not consider the
substitution of, or other changes in, metal- or mineral-bearing raw
materials that are used as feedstocks or materials inputs, * * * in
setting emission standards, work practice standards, operating
standards or other prohibitions or requirements or limitations under
this section for such categories and subcategories.

It should be noted that this language is not reflected in the
legislative text, which states without caveat that MACT standards may
be based on ``process changes, substitution of materials or other
modifications.'' CAA section 112(d)(2)(A).⁵⁴ However,
assuming that CKRC's request for these variances has merit, and if the
variances are incorporated in the final rule, they would apply to LWAKs
as well given that LWAK raw materials could also cause those combustors
to exceed the standards using MACT control. We solicit comment on
whether these variances are appropriate and workable, and on the
potential issues raised below.⁵⁵
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\54\ CKRC cites additional authority in its letter to B.
Holloway and F. Behan (USEPA) of March 10, 1997 addressing these
issues. Available in RCRA Docket # F-97-CS4A-FFFFF.
\55\ To meet its RCRA mandate, the Agency would continue to
evaluate emissions under the omnibus permit authority to ensure that
controls were adequate to protect human health and the environment.
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1. Variance for metals or chlorine in minerals and related process
materials. It may be appropriate to waive any MACT standard for a metal
or group of metals or the standard for HCl/Cl2 if the source documents
that it cannot comply with the standard while using MACT control solely
because of raw material feed. As examples, MACT control for Hg would be
hazardous waste feedrate control at a specified MTEC. MACT control for
SVM and LVM would also be feedrate control at a specified MTEC and
compliance with the PM standard. A condition of the variance could be
that the source would be required to document that the concentration of
metal or chlorine (for which it is seeking the variance) in hazardous
waste and any non-mineral feedstock is within the range of normal
levels for the industry. This would ensure that metals and chlorine
emissions attributable to non-mineral feedstreams are equivalent to
those from sources meeting MACT.
We therefore request comment on the following issues:
How would normal levels be determined? What statistics
should be used? What should be the baseline year for the determination
(e.g., a given year (2000, or the compliance date of the rule)?
Should the variance be granted only if the hazardous waste
and/or non-mineral feedstreams have lower than normal levels of metals
or chlorine? How much lower (e.g., 25th percentile levels, 40th
percentile levels)?
Would it be necessary to establish the normal levels in
the rule, or should they be established initially, on a case-by-case
basis?
Should the Agency be concerned if levels of metals or
chlorine in mineral feedstocks decline over time thus enabling the
source to meet the standard? If so, what monitoring approach would be
appropriate to identify when that occurred?
When should variance petitions be submitted to the State
or EPA regulatory officials (e.g., 120 or 180 days prior to the
compliance date)?
2. Variance for organics in minerals and related process materials.
Although current BIF regulations limit HC levels in kilns to 20
ppmv irrespective of the source of the hydrocarbons ⁵⁶ and
the Agency proposed to maintain that standard under MACT, CKRC notes
that some sources have to operate inefficiently to meet the standard.
For example, a source may have to operate back-end temperatures at
higher than normal levels to oxidize enough of the organics being
desorbed to meet the HC standard. This means that more fuel than normal
must be fired to provide the extra heat at the back-end.⁵⁷
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\56\ The Agency has acknowledged that HC in the main stack of a
long kiln can be generated by desorption of trace organics in raw
material feedstocks as well as from fuel combustion.
\57\ Higher back-end temperatures may be associated with higher
rates of D/F formation.
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CKRC has suggested approaches whereby a source can document that
hazardous waste is being burned in compliance with either the CO limit
of 100 ppmv or the HC limit of 10 ppmv.⁵⁸ In situations
where the kiln can monitor a representative sample of combustion gas at
mid-kiln at least temporarily during a performance test to document
compliance with the CO limit of 100 ppmv (or a HC limit of 10 ppmv),
limits on key combustion parameters would be established based on
operations during the performance test. The operating limits would be
continuously monitored to ensure compliance with the CO or HC limits.
Limits on the following operating parameters would be established: kiln
gas oxygen at the kiln outlet; kiln gas residence time using raw
material feedrate as a surrogate; and combustion zone temperature,
using an appropriate surrogate or measured at an appropriate location.
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\58\ Neither approach would appear to be appropriate for kilns
that feed hazardous waste at locations other than the clinker end.
The concern is that the kiln gas that is withdrawn for testing at
the mid-kiln location for compliance with the CO or HC limit may not
be representative of hazardous waste combustion gases (i.e., either
because the hazardous waste is being fired downstream or, if the
waste is fired at mid-kiln, the waste combustion gases may not be
thoroughly mixed at the point of kiln gas withdrawal for CO and HC
monitoring).
---------------------------------------------------------------------------

CKRC also suggested that sulfur hexafluoride (SF6) could be used as
a continuously monitored compliance parameter in lieu of limits on
other parameters, except oxygen. This is because SF6 is recognized as a
temperature labile compound--it is more stable than most any other
toxic compound under a temperature-failure mode of organics
destruction. SF6 is not, however, an indicator of oxygen-deficient
combustion failure modes--it is destroyed at high temperatures
irrespective of oxygen levels. Given that both adequate temperature and
oxygen are necessary for good combustion, an oxygen limit as well as an
SF6 feed limit and emission limit would be established under this
option based on a performance test documenting compliance with either
the CO or HC limits at mid-kiln.
Finally, CKRC suggested variance approaches for the more
problematic situation where a kiln is not able to sample kiln gas at
mid-kiln for compliance with the CO or HC limit. One approach would be
to allow a kiln to document compliance with the CO limit of 100 ppmv or
the HC limit of 10 ppmv in the main stack when burning hazardous waste
but temporarily feeding imported, low organic raw material. Under this
approach, as with the approaches discussed above, operating limits on
oxygen levels in kiln gas at the kiln outlet, residence time of
combustion gas, and combustion zone temperature would be established
based on a performance test using the low organic raw material. Also,
continuous monitoring of limits on feedrates and emission rates (based
on performance testing) of SF6 could be used in lieu of establishing
limits on residence time and temperature.
E. Emissions Averaging for Cement Kilns
Several cement kilns have unique design or operating procedures
that warrant special consideration in

[[Page 24240]]

demonstrating compliance with the MACT standards, as discussed below.
1. Preheater or Preheater/Precalciner Kilns with Dual Stacks. Some
preheater or preheater/precalciner kilns are designed with separate
main and alkali by-pass stacks. To demonstrate compliance with the
emission standards (other than the CO/HC standards where compliance is
based on emissions in either the main or by-pass stack), it is
appropriate to allow such kilns to document either that both stacks
meet the applicable emission limits, or that the stacks meet the limits
considering flow-weighted average emissions. This is the approach
currently used for compliance for the PM NSPS, and it is appropriate as
well for the MACT standards that the Agency has proposed.
2. Kilns that operate an in-line raw mill. Some cement kilns vent
the kiln gas through the mill that grinds the raw material (i.e., raw
mill) to help dry the raw material before charging to the kiln. Such
designs are referred to as ``in-line raw mills''. When the raw mill is
out of service for maintenance, approximately 10% of the time annually,
kiln gas by-passes the mill and is vented to the stack after passing
through the PM control device. (Stored milled raw material is charged
during these periods of mill downtime.) The Cement Kiln Recycling
Coalition indicates that emissions of HAPs that the Agency proposed to
regulate can be different when gas is vented through the raw mill
versus periods of time when the mill is out of service.⁵⁹
---------------------------------------------------------------------------

\59\ CKRC Comments, August 19, 1996, pp 112-113, Docket Number
RCSP-0170.
---------------------------------------------------------------------------

It appears appropriate to base compliance with the MACT emission
standards for such kilns on a time-weighted average basis. Sources
would use historical information on utilization time for the in-line
raw mill to document the time-weighted average and would present this
information to regulatory officials as part of the test plan. Further,
sources would be required to conduct performance testing under both
operating conditions: with the raw mill on-line and off-line.

III. DRE Testing Considerations

In the NPRM, the Agency proposed that the 99.99 percent destruction
and removal efficiency (DRE) standard be retained under RCRA authority.
See 61 FR at 17447. Although EPA could have proposed the DRE
requirement as part of the MACT standards to help control organic HAPs,
the Agency explained that doing so would have raised significant
practical implementation concerns. This is because MACT standards are
generally self-implemented by facilities to a large degree whereas DRE
testing has historically involved a detailed and iterative process
between a facility and the regulatory agency.
The Agency received comments that raised other concerns, including:
(1) Whether it is necessary for a source to actually perform a DRE test
to ensure that it is achieving DRE; ⁶⁰ and (2) how can the
Agency ensure that RCRA DRE testing is coordinated with MACT
performance testing.
---------------------------------------------------------------------------

\60\ The statutory minimum technology requirement for
incinerators (see RCRA 3004(o)(B)) requires the ``attainment'' of
99.99 percent destruction and removal efficiency. DRE testing could
be replaced by an alternative that is equally or more stringent
(e.g., compliance with stringent limits on CO or HC) to ensure
attainment of 99.99 percent DRE.
---------------------------------------------------------------------------

The Agency has reconsidered DRE testing issues and is today
requesting comment on options for ensuring compliance with a DRE
standard, and how to coordinate DRE testing with MACT performance
testing.
A. Options for Ensuring Compliance with a DRE Standard
The Agency has investigated whether compliance with the CO or HC
MACT standards would ensure that a source is achieving 99.99% DRE
⁶¹. The vast preponderance of the data indicate that when a
source is achieving CO levels under 100 ppmv or HC levels under 10
ppmv, it is virtually always also achieving 99.99% DRE.⁶²
The Agency's investigation noted, however, an atypical, failure mode
for the CO/HC versus DRE relationship: when low organic content waste
is fed into a region of a combustor other than the flame zone (e.g.,
into an unfired afterburner). One test condition of the approximately
455 investigated failed the CO/HC versus DRE relationship for this
reason. This was a highly unusual test condition, and does not
represent good combustion practice. CO levels were likely low because
flame combustion was not occurring, and HC was likely low because the
waste could have had only trace levels of toxic organics that did not
contribute significantly to the HC loading (but which could nonetheless
pose a health or environmental hazard).
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\61\ The Agency evaluated approximately 455 DRE test
conditions, where CO was less than 100 ppmv and 273 test conditions
where HC was less than 12 ppmv, to determine if compliance with
stringent CO and HC limits would ensure that 99.99% DRE was being
achieved. Ten sources failed DRE even though CO or HC levels were
below 100 ppmv or 12 ppmv (on a run average basis), respectively.
Nine of the failures could be explained by: (1) Selecting principal
organic hazardous constituents (POHCs) that were also common
products of incomplete combustion; (2) feeding low concentrations of
POHCs (a phenomenon of DRE testing is that it is very difficult to
measure 99.99% DRE when POHCs are fed at low concentrations, even
though emission concentrations may be trivial); or (3) feeding
aqueous waste with such low concentrations of organics that, even
under poor combustion conditions, the waste did not generate high
levels of CO or HC. See USEPA, ``Draft Technical Support Document
for HWC MACT Standards (NODA), Volume II: Evaluation of CO/HC and
DRE Database'', April 1997.
\62\ It could be argued that this is due to two factors: (1)
during successful DRE testing many sources operated at CO or HC
levels that were well below the 100/10 levels; and (2) it is not
clear that those sources would continue to achieve 99.99% DRE at
higher CO or HC levels (but not exceeding the 100/10 levels). This
is unlikely to be a major concern, however, because combustion
devices operating at CO levels under 100 ppmv are generally
considered to be operating under good combustion conditions that
would ensure 99.99% DRE in any event.
---------------------------------------------------------------------------

Given the general relationship between CO, HC, and DRE and the
highly unusual nature of the lone exception, the Agency is considering
whether DRE testing is warranted in all cases for sources complying
with the MACT CO and HC standards. The DRE test is a complicated,
expensive test. In addition, although it can help indirectly to ensure
that a source is operating under good combustion conditions, it may not
provide the operationally direct level of assurance of good combustion
conditions that CO or HC does. The data show that sources can be
achieving 99.99% DRE even though CO or HC levels exceed values
considered to represent good combustion (i.e., CO of 100 ppmv, HRA, and
HC of 10 ppmv, HRA).⁶³
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\63\ Under an option the Agency is considering for establishing
MACT standards for CO and HC, a source would be able to elect
whether to comply with either the CO or HC standard. Although CO is
not a direct measure of HC emissions, the Agency is considering
requiring sources that elect to comply with the CO standard to
document that their HC emissions also meet the standard.
---------------------------------------------------------------------------

Accordingly, the Agency is considering three options for reducing
the DRE testing burden, as discussed below.⁶⁴ Under all
options where DRE testing would be waived, a source would have to be in
compliance with the final MACT standards for CO/HC, which will be
sufficient to show ensure compliance with the DRE standard as
well.⁶⁵
---------------------------------------------------------------------------

\64\ The Agency's analysis to date has focused on the 99.99% DRE
standard. We have not investigated whether sources that burn
``dioxin-listed waste'' under Sec. 264.343(a)(2) and are required to
demonstrate 99.9999% DRE are likely to achieve that DRE when
operating under stringent CO and HC levels. Given that there are few
HWCs that are permitted to manage such wastes and given the high
toxicity potential of such wastes, the Agency is inclined to
continue to require DRE testing at facilities handling those wastes.
\65\ Long cement kilns generally cannot meet the stringent CO
and HC limits applicable for waste combustion (i.e., 100/10 ppmv)
because of organics in raw materials. Thus, the Agency proposed that
such kilns comply with a CO level of 100 ppmv or a HC level of 20
ppmv. Notwithstanding the inability to document good combustion
conditions by complying with stringent CO/HC limits, the Agency
believes that cement kilns that fire hazardous waste into the
clinker end of the kiln will virtually always achieve 99.99% DRE
because, to make marketable products, clinker temperatures must be
approximately 2700 deg. F, and combustion gas temperatures are
typically several hundred degrees hotter than the solids
temperature. These temperatures are theoretically high enough to
ensure destruction of organic compounds in the waste. Consequently,
such kilns should not be precluded from the waivers discussed in the
text. If such a kiln were to inject hazardous waste at nonflame zone
locations such as mid-kiln or at the raw material end of the kiln,
however, we are concerned that DRE may not always be achieved. The
kiln would not be eligible for the DRE waiver.

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[[Page 24241]]

B. DRE As a MACT Versus RCRA Standard
In investigating approaches to ensure coordination of DRE testing
with MACT performance testing, the Agency has reconsidered whether the
DRE standard could be effectively implemented as a MACT standard (to
help control organic HAPs). To ensure coordination of DRE and MACT
performance testing, the Agency is considering extending the test plan
review period from the proposed 60 day period (see proposed
Sec. 63.1208(e) and Sec. 63.7(b)(1)) to one year to allow regulatory
officials time to consider DRE testing in context with MACT testing.
With this opportunity for coordinating the testing, the Agency's
concerns expressed at proposal about the difficulty of implementing the
DRE standard under the self-implementing regime of MACT may be largely
overcome (i.e., if the Agency incorporates into the MACT standards
opportunity to review and approve the DRE test protocol). Thus, the
Agency is considering incorporating the DRE standard as a MACT
standard.
Sources wishing to perform a combined DRE and comprehensive
performance test would have to submit the test plan one year in advance
of the test. If the review requires more than one year, the Agency can
extend the testing date for coordination purposes (assuming the source
has made a good faith effort to cooperate with regulatory officials to
identify an appropriate test protocol). However, there would be no
extensions granted for the initial comprehensive performance test
because it is imperative that sources document compliance with the MACT
emission standards (including those for the high priority HAPs, D/F,
Hg) on schedule. Sources wishing to perform a combined initial
comprehensive performance and DRE test would therefore have to be
diligent in working with regulatory officials to ensure that the
combined test protocol is developed and approved in a timely
manner.⁶⁶
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\66\ The Agency also considered requiring sources to submit
draft test protocols one year prior to the test date, regardless if
the comprehensive performance test is to be combined with a DRE
demonstration. We determined that may not be appropriate, however,
because normal comprehensive performance tests should not require a
review process longer than provided by the CAA-MACT general
requirement. Therefore, the one-year test review period would only
apply for those sources that wish to coordinate the comprehensive
performance (or confirmatory) test with a DRE test.
---------------------------------------------------------------------------

The Agency invites comment on these issues, including whether DRE
should be incorporated as a MACT standard, and irrespective of that
decision, whether a one-year review period provides adequate
opportunity to review a combined DRE test and comprehensive performance
test protocol.

IV. Notification and Reporting Requirement Considerations

A. Public and Regulatory Notification of Intent to Comply
In the proposed rule, the Agency requested comment on strategies to
encourage or require affected sources to comply with the final
emissions standards at the earliest possible date. The Agency also
asked for views on methods that could be used to determine when a
source could realistically conclude whether it will comply in a timely
fashion with the final standards (61 FR at 17416). A number of
commenters argued for the Agency to require a submission from affected
sources that identifies whether and how the facility intends to comply
with the final standards. This notification requirement was referred to
as a ``Notification of Intent to Comply.'' The purpose of the
submission would be to identify the sources that will not comply with
the final standards so that those sources could be forced to terminate
waste burning activities as soon as possible following the effective
date of the final HWC rule.
Other commenters, responding to our request for comment regarding
the proposed permit modification options (61 FR at 17455), suggested
that all facilities be required to submit a plan that outlines the
procedures each facility intends to follow to comply with the final
standards. However, the purpose of this submission would be to begin an
early process of communication between the public and the facility
through the public disclosure of the facility's compliance strategy.
The Agency has reviewed these comments and supports the goals and
purposes of a requirement that compels sources to identify their
intentions to comply with the final rule, and to describe how they will
achieve that compliance. Furthermore, the Agency supports any process
that promotes public notification and interaction with respect to a
hazardous waste combustor's future operations. To the extent that some
limitations on public participation would be the result of a
streamlined permit modification process that may be finalized ahead of
the HWC MACT rule, promotion of early public notification and
intervention in this part of the rule is appropriate and desirable
given our general policies in that regard (see, e.g., RCRA Expanded
Public Participation Rule, 60 FR 63417 (Dec. 12, 1995)). Therefore, the
Agency is considering a notification requirement, based on and growing
out of ideas that were presented in comments, that may be applied to
sources affected by the final rule. This notification requirement,
called the Public and Regulatory Notification of Intent to Comply
(PRNIC), would involve the facility submission and public disclosure of
a plan that relates to whether and how the facility intends to come
into compliance with the final standards.
However, due to enforcement and implementation issues, the Agency
is concerned that it is not feasible to use a submission that
identifies only a facility's future ``intentions'' as the legal basis
to force a facility to terminate waste burning activities before the
statutorily based compliance period of three years. Moreover, any
official review and approval of such submissions could conceivably slow
down the rate at which facilities come into compliance with the final
standards. This would thwart the objectives of a streamlined permit and
compliance process.
The Agency believes that the most effective application of such a
submission is to promote public awareness, as well as discussion
between a facility and its community, which will afford them an
opportunity to engage in discussions regarding the details of the
facility's plans to comply with the final standards. However, the
Agency does not intend for this submission to undergo a formal review
by the regulatory agencies involved.
The Agency requests comment on this option which requires sources
to prepare and submit for public comment a notification identifying the
source's intentions to comply with the final rule as well as the
strategy they intend to follow to assure compliance by the compliance
date. This notification requirement would apply to all sources

[[Page 24242]]

burning waste on the effective date of the final HWC rule, and would
require sources to prepare a draft notification, announce the
availability of the draft notification as well as a future informal
public meeting to discuss the draft notification, hold an informal
public meeting, submit the final notification to all appropriate
regulatory agencies, and update the notification as necessary.
The Agency intends for the information contained in the draft
notification to provide enough detail so that the public can engage in
a meaningful review of the facility's compliance strategy. For example,
if in the draft notification a facility identifies and describes the
type(s) of control technique(s) being considered, the facility should
include, as appropriate, waste minimization and/or pollution control
options that may have been evaluated.
EPA also requests comment on a requirement for affected sources to
hold at least one informal meeting with the public before submitting
the final notification to the appropriate regulatory agencies. The goal
of this informal meeting is to provide a forum to facilitate dialogue
between the affected source and its community. The meeting should
provide an open, flexible and informal occasion for the facility and
the public to discuss various aspects of the facility's compliance
strategy because it provides the public direct input to the facility
owners/operators. In addition, the meeting affords facility owner/
operators the opportunity to gain an understanding of the public's
expectations, which can then be addressed and included in the
facility's final submission. The Agency anticipates that the facility
and the public will share ideas, educate each other, and continue to
establish a framework for sound communication. However, as suggested in
comments received from CKRC,⁶⁷ the Agency understands that
the early timing of the meeting may affect a facility's ability to have
complete or fully accurate information, but the Agency believes that
the benefits of early public involvement and access to information
outweigh the drawbacks of incomplete information. Furthermore, the time
period between the effective date of the HWC rule and the informal
meeting announcement should provide a facility sufficient time to
collect, analyze, select, and plan a compliance strategy. However,
comments are invited on other appropriate time periods between the
public notification and the informal public meeting, and on the time
period necessary to collect the information required for the PRNIC.
---------------------------------------------------------------------------

\67\ Memorandum, from Craig Campbell (CKRC) to Matthew Hale Jr.
(EPA), regarding compliance plans under the HWC MACT Rule, dated
March 18, 1997.
---------------------------------------------------------------------------

Another timing issue relates to when a facility should notify the
community regarding the availability of the draft PRNIC. At this stage,
the Agency is considering to require that the notification be made on
or before 210 days following the effective date of the final HWC rule.
This would necessitate that an announcement of the informal public
meeting and the availability of the draft PRNIC be made 30 days prior
to the meeting in a manner that is likely to reach all affected members
of the community. The Agency is considering that this announcement, of
the informal public meeting and draft PRNIC availability, should be
required in three ways: As a display advertisement in a newspaper of
general circulation; as a clearly marked sign on the facility property;
and as a radio broadcast. Each of these notices would have to include
the date, time and location of the meeting, a brief description of the
purpose, a brief description of the facility, a statement asking people
who need special access to notify the facility in advance, and a
statement describing how the draft PRNIC can be obtained. The Agency
requests comment on this approach that requires facilities to hold an
informal public meeting prior to the submission of the final PRNIC to
the regulatory authorities.
An additional requirement of the notification approach being
considered involves the submission, to the appropriate regulatory
agencies, of the final PRNIC 270 days following the effective date of
the final HWC rule. The submission would contain the following
information: The name and location of the owner operator; the location
of the source; a statement as to whether the source is a major or area
source; a description of any waste minimization and pollution control
technique(s) considered; a description of the emission monitoring
technique(s) considered; a description of the waste minimization and
pollution control technique(s) effectiveness; a description of the
evaluation process used to select the waste minimization and/or
pollution control technique(s); and an outline of the key dates in the
process that the facility plans to follow to implement the selected
waste minimization and/or pollution control technique(s). This
submittal should also capture the major comments or ideas that were
discussed in the public meeting or that were submitted in response to
the release of the draft PRNIC.
The final requirement of the notification approach being considered
involves updates to the final PRNIC following a significant change in
the facility's implementation strategy. A significant change would be
analogous to a change that would trigger a RCRA class two or class
three permit modification request, and would apply only to changes that
depart from the strategy described in the final PRNIC. Examples of some
changes that may be considered significant changes are as follows: A
change in the pollution control technique to be implemented; a request
for permit modification; a request for an extension of the compliance
date; or a decision to stop or to continue burning waste that is
contrary to the final PRNIC. Additionally, all sources could be
required to notify the public via a mailing to the facility's mailing
list within 30 days following a determination that a significant change
has occurred in the facility's implementation strategy. The change
would have to be described in writing and made available to requesting
parties via placement in an information repository or through direct
transmittal. This requirement would be in keeping with the spirit of
the PRNIC, which is to keep the public informed of any significant
changes in the facility's compliance and implementation plan.
The Agency invites comment on this submittal and the submittal
process, and requests information on the benefits and burden associated
with such a process. The Agency specifically invites comment on the use
of permit modification criteria to identify a significant change that
would necessitate an update to the PRNIC.
B. Data Compression Allowances
The Agency is considering allowing the use of data compression
techniques in the recording of continuously monitored parameters under
this rule. This is in response to comments on the proposed rule
regarding the additional burden associated with the proposed monitoring
and recording requirements and specific requests to allow data
compression. We are also considering revisions to parts 264, 265 and
266 that would be conforming revisions to ensure that the RCRA rules
are consistent with similar provisions of the proposed part 63 rules.
Commenters raised the issue of an additional burden by the proposed
monitoring and recording requirements. We do not agree that the
proposed requirements pose significant additional record keeping
burdens from current regulations (i.e., BIF rule) or existing

[[Page 24243]]

permit requirements under RCRA. However, we are interested in reducing
the information burden--for example, how much is recorded if the data
is automatically evaluated under an established set of specifications,
while maintaining the integrity of the data for compliance evaluation
purposes.
Briefly, 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 proposed in rule. One-minute averages
will continue to be generated. However, with data compression, each
one-minute average will be automatically compared with a set of
specifications to decide the need for recording. New data is recorded
when the one-minute average value falls outside the set of
specifications.
This option should provide a good opportunity to the regulating
agencies to focus their review of operating data, because facilities
using data compression will record data that is indicative of non-
steady state operations more frequently than steady state operations.
This will significantly reduce, up to 90%, the data subject to review
by the regulating agency as the facilities' self-evaluate, under a
previously approved set of specifications, the data being recorded.
The dynamics of monitored parameters are not uniform across the
regulated universe, and establishing national specifications for data
compression techniques in this rule may not be feasible. Different data
compression techniques can be successfully implemented for a monitored
parameter to obtain compressed data that reflect the performance on a
facility specific basis. As a result the Agency is considering allowing
the sources to request the regulatory agency to use data compression
techniques that reflect site-specific conditions of the monitored
parameters and establish data compression specifications accordingly.
Upon approval, sources may start data compression techniques based on
the approved set of specification.
At a minimum, a source implementing data compression will be
required to record a value once every ten minutes. In combination with
the appropriate set of specifications, a recorded value every ten
minutes will result in a potential data recording reduction up to 90%.
As a guideline, for the regulating agencies and sources EPA has
developed a table to use as a guideline developing site-specific
specification for data compression techniques. These are the basis for
the specification in the table:
1. Data compression limit. The closest level to a permit limit/
standard at which reduced recording is allowed. Within this level,
minute-by-minute data recording is required. The data compression limit
should reflect a level at which the specific parameter is unlikely to
exceed its permit limit within a one-minute change. The other
consideration is to set a data compression limit at which owners and
operators can practically implement data compression.
2. Fluctuation limits. The permissible deviation of new data value
from previously generated value. This parameter is a reflection of
tolerance of the agency to allow a parameter to change without
requiring the data point to be recorded. The considerations to
establish the fluctuation limits are (1) The potential of the regulated
parameter to change in one minute and cause an exceedance of the permit
limit on a rolling average basis and; (2) the maximum variation
tolerated from a change of other related operating parameters (i.e.,
fuel and temperature, gas flow and APCD parameters).
We invite comment on allowing data compression under this rule,
including revising parts 264, 265 and 266, and on the following table:

Fluctuation and Data Compression Limits Expressed as Percentages of the Permit/Standard Limits
----------------------------------------------------------------------------------------------------------------
Fluctuation limit ^{plus-
Device Parameter ^{minus Data compression limit
----------------------------------------------------------------------------------------------------------------
CEMS.............................. Particulate matter... 10%................... 60%.
CEMS.............................. Carbon monoxide 1 10 ppm................ 50 ppm.
hour.
CEMS.............................. Total hydrocarbon.... 2 ppm................. 60%.
CEMS.............................. Total mercury 10 hour 10%................... 60%.
CEMS.............................. Multi-metal 10 hour.. 10%................... 60%.
HCl.................. 10%................... 60%.
Chlorine............. 10%................... 60%.
Max inlet temperature 10 deg. F............. Limit -30 deg. F.
to dry PM APCD.
Activated carbon injection........ Min carbon injection 5%.................... Limit +20%.
feedrate (carbon
feed through
injector).
Min carrier fluid 20%................... Limit +25%.
flowrate or nozzle
pressure drop.
Dioxin inhibitor.................. Min inhibitor 10%................... 60%.
feedrate.
Catalytic oxidizer................ Min flue gas 20 deg. F............. Limit +40 deg. F.
temperature at
entrance.
Max flue gas 20 deg. F............. Limit -40 deg. F.
temperature at
entrance.
Maximum waste 10%................... 60%.
feedrate.
Min combustion 20 deg. F............. Limit +50 deg. F.
chamber temperature
(exit of each
chamber).
Good combustion and APCD Maximum flue gas 10%................... 60%.
efficiency. flowrate or
production rate.
Feed control...................... Maximum total metals 10%................... 60%.
feedrate (all
streams).
Maximum pumpable
liquid metals
feedrate.
Maximum total ash 10%................... 60%.
feedrate (all
streams).
Maximum total 10%................... 60%.
chlorine feedrate
(all streams).
Wet scrubber...................... Minimum pressure drop 0.5'' water........... Limit +2''.
across scrubber.
Min liquid feed press 20%................... Limit +25%.
Minimum liquid pH.... 0.5 pH unit........... Limit + 1 pH unit.
Min blowdown (liquid 5%.................... Limit +20%.
flowrate) or max
solid content in
liquid.
Minimum liquid flow 10%................... Limit +30%.
to gas flow ratio.
Ionizing wet scrubber............. Minimum pressure drop 0.5'' water........... Limit +2'' water.
across scrubber.
Minimum liquid feed 20%................... Limit +25%.
pressure.
Min blowdown (liquid 5%.................... Limit +20%.
flowrate) or max
solid content in
liquid.
Minimum liquid flow 10%................... Limit +30%.
to gas flow ratio.
Min power input (kVA: 5%.................... Limit +20%.
current and voltage).
Dry scrubber...................... Min sorbent feedrate. 10%................... Limit +30%.

[[Page 24244]]

Minimum carrier fluid 10%................... Limit +30%.
flowrate or nozzle
pressure drop.
Fabric filter..................... Minimum pressure drop 1'' water............. Limit +2'' water.
across device.
ESP............................... Min power input (kVA: 5%.................... Limit +20%.
current and voltage).
----------------------------------------------------------------------------------------------------------------

V. Waste Minimization and Pollution Prevention

A. Overview
Amendments to RCRA in 1984, and the Pollution Prevention Act of
1990 establish a clear national policy preference for pollution
prevention and environmentally sound recycling as the nation's top
priority environmental management methods, over treatment, storage and
disposal. Pollution prevention, also referred to as source reduction,
includes any practice that reduces the amount of pollutants entering a
waste stream, prior to recycling, treatment or disposal. Waste
minimization, a term particular to RCRA and EPA's hazardous waste
program, includes pollution prevention (or source reduction) and
environmentally sound recycling. Combustion for treatment or
destruction is a form of treatment, and is not included in the
definitions of pollution prevention, source reduction, waste
minimization and/or environmentally sound recycling.
Based on previous studies, stringent limits on pollution control
devices generally provide a strong incentive for companies to pursue
less costly waste minimization measures to achieve compliance. The
implementation of the Land Disposal Restrictions program has shown this
to be the case in the RCRA program. Waste minimization measures can, in
many cases, provide companies with a variety of benefits, including:
improvements in production yields, reduced worker exposure, reduced
waste volumes, reduced waste management costs, reduced liability, and
reduced compliance burdens. As a result, many companies, including
those affected by today's rulemaking, have made significant progress
identifying and installing waste minimization measures that result in
one or more of these benefits. In addition, hazardous waste generators
that transport waste off-site for treatment, storage or disposal are
required to certify on each hazardous waste manifest that they have a
waste minimization program in place. In addition, facilities that have
a RCRA permit to treat, store or dispose of hazardous wastes are
required to certify annually that they have a waste minimization
program in place (See sections 3002(b) and 3005(h) of RCRA).
Past studies indicate that existing regulations can also contain
inherent barriers that prevent companies from identifying and
installing additional waste minimization measures that could be cost
effective and provide an alternative or supplemental means to achieve
compliance. Potential regulatory impediments can include: Tight
compliance deadlines that preclude taking extra time to explore waste
minimization alternatives, perceptions that end-of-pipe technology is
preferred by government agencies over less well known waste
minimization measures to achieve compliance, a tendency to continue
relying on pollution control technology once a company has sunk
available capital into end-of-pipe controls, and a lack of government
willingness to explore more flexible compliance approaches.
During extensive interaction with public stakeholders during the
development of EPA's Hazardous Waste Minimization National Plan
(released in 1994), some companies emphasized that short compliance
deadlines after the promulgation of end-of-pipe standards are a
significant impediment to fully identifying and installing waste
minimization measures that could either replace or supplement end-of-
pipe pollution control measures that may still be necessary. As a
result, companies are likely to opt for installing ``end-of-pipe''
pollution controls to meet compliance deadlines, instead of pursuing
waste minimization and pollution control measures as a compliance
approach. At large complex manufacturing facilities (such as chemical
manufacturing plants), short compliance deadlines are a particular
barrier since completing a waste minimization options assessment
requires consideration of chemical reaction redesign, testing and
installation. In contrast end-of-pipe controls can often be installed
more quickly than waste minimization process changes, even though they
may be more expensive. In addition, once capital has been sunk into
end-of-pipe pollution controls, there is little incentive for companies
to then spend money exploring pollution prevention/waste minimization
options that would offset the need for the end-of-pipe controls. This
factor is one of the major factors to consider in today's rulemaking.
This is discussed in more detail below.
B. EPA Proposed Flexible Waste Minimization Incentives
EPA was aware, in its April 1996 proposal for this rulemaking, that
promulgating MACT standards may contain some inherent barriers to
identifying and installing waste minimization technologies that could
be more cost effective for meeting environmental protection standards
(in some cases) than end-of-pipe air pollution control equipment alone.
Consequently, EPA requested comment on three regulatory incentives that
could partially offset potential barriers and provide regulated
companies with an increased opportunity to identify and install waste
minimization technologies that reduce or eliminate hazardous waste
entering combustion feed streams as a cost effective approach to
compliance. EPA's objective in this effort is to promote flexibility in
the use of waste minimization measures that would reduce the amount
and/or toxicity of hazardous wastes entering combustion feed streams,
either as an alternative to end-of-pipe combustion measures, or in
combination with combustion measures, to meet MACT standards.
EPA requested comment on two approaches that use waste minimization
facility planning to identify cost effective waste minimization
measures that reduce hazardous wastes entering combustion feed streams.
Waste minimization planning has been used in over 20 states as a method
to encourage companies, particularly those that generate and manage
wastes on site, to identify cost effective waste minimization measures
that can be used in place of, or in combination with, end-of-pipe
pollution control measures. Of the 21 commercial incinerators and the
141 on-site hazardous waste incinerators facilities known to be covered
by today's rule, 43-44 percent

[[Page 24245]]

of the facilities are in states that have mandatory waste minimization
planning programs; 14 percent are in states that have voluntary waste
minimization planning programs; and 42-43 percent are in states that do
not have formal waste minimization planning programs.
The first waste minimization facility planning approach proposed
for comment sought to encourage facilities to reduce the amount of
hazardous waste entering combustion feed streams as much as possible
through cost effective waste minimization measures. The proposal sought
to accomplish this objective by requiring all facilities covered by
this rulemaking to provide to the appropriate EPA or State permitting
authority adequate information on waste minimization measures that
would reduce hazardous wastes entering combustion feed streams.
Requiring facilities to formally consider cost effective waste
minimization options would raise the likelihood that hazardous waste
generation could most cost effectively be reduced at the source or
recycled, as a preferred approach to combustion. Since many of these
facilities are located in states that have mandatory or voluntary waste
minimization planning programs, EPA hoped to build on a process already
in place. States that have mandatory waste minimization planning
programs generally require facilities to provide a description of
changes in process equipment, raw materials, materials handling,
recycling, maintenance or other changes that would reduce the amount
and/or toxicity of wastes that are treated or disposed. None of the
existing mandatory or voluntary State waste minimization planning
programs specifically address reductions of combusted hazardous as an
objective of the planning process. EPA requested comments on this
approach to determine if the approach could provide greater flexibility
for facilities to build on requirements of existing state programs to
achieve compliance with MACT standards.
In the second waste minimization planning option, EPA proposed to
provide EPA Regions and States with the discretionary authority to make
case by case determinations regarding which facilities would be
required to provide information on waste minimization alternatives to
reduce hazardous wastes entering combustion feed streams. This
determination could take into account several factors, including, for
example, whether an existing state program had already accomplished the
equivalent of this objective, the extent to which this requirement may
be too burdensome for some states, and the extent to which facility
specific conditions indicate emissions could be best controlled by feed
stream management and waste minimization at the source.
The third waste minimization incentive EPA proposed for comment
allows facilities to apply for up to a one year extension to the three
year compliance period allowed under the CAA and 40 CFR
63.6(i)(4)(i)(A) in cases where facilities need additional time to
identify and install waste minimization measures that would reduce
hazardous wastes entering combustion feed streams as a method (either
alone or in combination with combustion or other treatment technology)
to achieve compliance. 40 CFR 63.6(i)(6)(i) describes the requirements
for requesting a compliance extension. A request must include a
description of the pollution control, process changes or process
equipment to be installed, a compliance schedule that describes the
dates by which these controls, process changes and process equipment
will be initiated, the dates by which installation will be completed,
and the date by which compliance will be achieved. The Administrator or
a State that has an approved Part 70 permit program or has been
delegated the authority to implement and enforce the emission standard
for that source may grant such extensions. This incentive would, at
least in part, offset some of the time barriers large companies might
need to fully explore and install waste minimization options in
addition to any combustion equipment that may still be necessary.
C. Comments Received
EPA received comments on waste minimization from 22 commenters.
Companies that operate on-site units (many of which are large chemical
plants) commented that, while waste minimization can provide a cost
effective approach to compliance, neither the three year compliance
period allowed for this rule, nor the three years plus a one year
extension is sufficient time to complete the two track task of
designing, testing and installing waste minimization process changes
that reduce hazardous wastes entering combustion feed streams, and
designing and installing any combustion or other treatment equipment
that may nevertheless be necessary. Waste minimization is an on-going
process that should be continually under investigation in all
companies. However, EPA agrees that in cases where standards are
promulgated that change the economics of how much pollution can be
emitted to the environment, even on-going waste minimization programs
may not be able to anticipate the best combination of waste
minimization and treatment measures to achieve compliance. EPA agrees
that in some cases, particularly at large complex manufacturing
operations, the three year compliance period may not be sufficient time
to consider waste minimization measures, and in other cases, three
years plus a one year extension may not provide sufficient time.
Commercial facilities continue to assert that they have few direct
opportunities to pursue waste minimization since they have little
control over the wastes generated by their customers. Some commercial
companies believe EPA should implement ``good actor'' incentives for
companies that educate their customers regarding available waste
minimization resources. Such incentives could include reduced
inspection frequencies, reduced performance testing, and a recognition
program. EPA agrees that commercial combustors of hazardous waste have
little direct control over the wastes generated by their customers and
therefore will experience little if any flexibility from any the waste
minimization incentives proposed for comment. The comment to implement
good actor incentives as an incentive for commercial companies to
educate their customers on waste minimization did not contain
sufficient information to determine the merits of such an approach. EPA
does point out, however, that this type of concept, i.e., one in which
private industry proposes an improvement in environmental performance
through and innovative regulatory approach, is the type of approach
that might be appropriate for further exploration at a later time.
Three states commented. Two states believe EPA should encourage
waste minimization in this rulemaking. However, they believe three
years plus a one year extension may not be enough time for companies to
identify and install waste minimization measures. The third state said
that waste minimization incentives should not be necessary in this rule
because companies have had many years to pursue waste minimization
programs and should have already considered waste minimization as an
approach to compliance. EPA agrees with the two states that, in some
cases, three years plus a one year extension may not be sufficient time
to identify and install waste minimization measures that achieve
compliance. EPA agrees with the third state to a limited extent, in
that companies have had many years to

[[Page 24246]]

implement waste minimization programs, and notes that most, if not all,
of the companies affected by today's rulemaking probably have waste
minimization programs in place. However, as noted earlier, waste
minimization is an on-going process, and the stringent requirements of
the MACT standards for hazardous waste burning facilities may shift the
economics for particular companies in a way that makes certain waste
minimization measures more cost effective than they otherwise would
have been, and companies may need additional time to design and install
these approaches.
EPA's Interim Final Guidance to Hazardous Waste Generators on the
Elements of a Waste Minimization Program in Place (May 28,1993)
recognizes companies make these determinations on a case by case basis.
EPA's guidance describes six general program elements that contribute
to successful corporate waste minimization programs. These elements
include: (1) Top management support that emphasizes waste minimization
in its corporate policy, employee involvement and rewards for ideas
that reduce waste generation, setting goals for waste reduction, and
other proactive management steps; (2) characterization of waste
generation and waste management costs, identification of sources of
waste in the production process, how they were generated, the value of
raw materials and lost products that are escaping as waste, and the
cost of replacing and managing wasted materials; (3) periodic waste
minimization assessments that are tied into other efforts to improve
environmental management; (4) a cost allocation system that assigns the
true cost of generating and managing wastes to the activities that
generate the waste in the first place; (5) encourage technology
transfer that shares ideas and technology between parts of the
organization and with other organizations where appropriate; and (6)
program implementation and evaluation that evaluates successes and
failures, and shares information with the public. While these
principles were published in regard to RCRA's waste minimization
certification requirement, the principles can be used as relevant
guiding principles by companies who wish to consider using waste
minimization measures as a method to reduce hazardous wastes entering
combustion feed streams regulated under MACT standards and the Clean
Air Act.
One company argues in its comments that mandatory waste
minimization planning should be made a MACT requirement so that
facilities are forced to consider source reduction and recycling
alternatives, rather than simply installing end-of-the-pipe equipment
to control HAP emissions. The company argues that this approach would
be particularly useful in controlling combustion feed streams to limit
the combustion of metals and other constituents that can not be
adequately controlled using end-of-pipe measures.
EPA has examined this issue closely. While mandatory facility
planning on the surface may appear to force facilities to consider
waste minimization solutions, providing appropriate regulatory
incentives and harnessing the power of public dialogue for companies to
identify and install waste minimization measures will result in more
waste minimization measures.
Sixteen states have implemented mandatory waste minimization
planning programs and several more have implemented voluntary waste
minimization planning programs in an effort to encourage facilities to
pursue waste minimization measures over end-of-pipe measures. A Federal
mandatory and prescriptively detailed waste minimization planning
requirement would be, at best, marginally effective in causing large
companies (which make up the population of facilities affected by
today's regulation) to identify and install waste minimization measures
beyond what they would do under current requirements. Large companies
generally already have the necessary staff, information, and resources
to pursue waste minimization alternatives where it makes sense to do
so. Whether large companies choose waste minimization solutions over
end-of-pipe solutions depends on a variety of economic and other
factors that outweigh attempts to identify additional waste
minimization alternatives. EPA hopes to encourage minimizing
impediments to waste minimization by soliciting comments on the
approaches contained in today's NODA. Furthermore, the remaining States
have chosen to not implement mandatory or voluntary waste minimization
planning programs. Some States believe that mandatory waste
minimization planning does not improve waste minimization results. It
would not be appropriate for EPA to either add additional burden to
State waste minimization programs that already exist or to States that
have chosen not to have waste minimization planning programs.
EPA is, instead, asking for comment on a refined approach that
encourages facilities to consider waste minimization alternatives, uses
public dialogue to advance waste minimization efforts, and provides
regulatory incentives for companies to pursue waste minimization
solutions. This approach will achieve many of the same ends more
efficiently than a detailed and prescriptive mandatory waste
minimization planning requirement.
D. Comments Requested on Additional Waste Minimization Incentives
EPA is requesting comment on a three regulatory incentives that are
intended to encourage companies to pursue waste minimization measures
to reduce or eliminate hazardous wastes entering combustion feed
streams.
The first incentive was proposed in EPA's April 19, 1996 MACT
proposal, and is being refined in today's NODA. EPA requested comments
on granting regulated facilities the opportunity to request a one year
extension to the three compliance period allowed under the Clean Air
Act in cases where the additional time is clearly needed to identify
and install waste minimization measures that would reduce the amount of
hazardous waste combusted as a means of achieving compliance. In
today's NODA, EPA is requesting comment on several clarifying factors
that will promote consistency while still allowing flexibility in
decision-making among the EPA Regions and authorized States who will
make determinations on whether or not to grant one year extensions to
facilities who apply.
EPA is also requesting comment on extending the agency's current
audit and penalty policies to allow some companies to enter into a
written consent agreement or consent orders (CA/COs) in cases where it
is clear that longer than four years (i.e., longer than a one year
extension) is needed to identify and install waste minimization
measures that significantly reduce hazardous wastes entering combustion
feed streams. These two approaches are discussed more below.
40 CFR 63.6(i) describes the authority, procedures and requirements
for requesting a one year compliance extension for meeting MACT
standards. Requests must include certain information, including: A
description of the pollution control, process changes or process
equipment to be installed, a compliance schedule that describes the
dates by which these controls, process changes and process equipment,
will be initiated, the dates by which installation will be completed,
and the date by which compliance will be achieved. Today, EPA is
requesting comment on language that clarifies the term ``process
changes'' in 40 CFR 63.6(i)(6)(i)(B)

[[Page 24247]]

solely with respect to hazardous waste burning incinerators, LWAKs and
cement kilns, to make it clear that waste minimization measures are
included in the meaning of process changes for meeting MACT standards.
By making this clarification, EPA hopes to encourage the use of
waste minimization measures to reduce the amount of hazardous waste
entering combustion feed streams as an alternative to or supplement to
end-of-pipe emission controls. With respect to hazardous waste burning
incinerators, LWAKs and cement kilns, EPA includes in the definition of
``process changes'' the following activities: equipment or technology
modifications, reformulation or redesign of products, substitution of
raw materials, improvements in work practices, maintenance, inventory
control, and environmentally sound recycling measures which reduce the
amount and/or toxicity of hazardous waste entering feed streams of
combustion devices. The term environmentally sound recycling includes
on-site (including closed-loop recycling) and off-site recycling
activities that use, reuse or reclaim hazardous materials in accordance
with EPA regulations. Burning for energy recovery is not included in
the meaning of ``process change'' as a basis for requesting a one year
extension for waste minimization purposes. This proposed definition
would apply only to hazardous waste burning incinerators, LWAKs and
cement kilns.
The Administrator or a State that has an approved part 70 permit
program (or has been delegated the authority to implement and enforce
the emission standard for that source) may grant extensions under 40
CFR 63.6(i)(9). Under this approach, decisions to grant one year
extensions will be made by EPA Regional offices and approved or
delegated state programs. EPA recognizes that States employ a variety
of approaches for requiring or encouraging the consideration of waste
minimization measures in achieving compliance with regulatory
requirements. It is not appropriate for EPA to supersede State
approaches with a uniform set of criteria for evaluating waste
minimization requests for one year compliance extensions. However, EPA
believes it is appropriate to encourage (but not mandate) consistency
in how these decisions are made. Therefore, EPA is requesting comment
on a proposal to include four factors that must, at a minimum be
considered by EPA Regional offices and approved or delegated state
programs in approving or denying requests for one year compliance
extensions for hazardous waste burning incinerators, LWAKs, and cement
kilns). These factors include:
The extent to which the process changes (including waste
minimization measures) proposed as a basis for the extension reduce or
eliminate hazardous wastes entering combustion feed streams and are
technologically and economically feasible.
Whether the magnitude of the reductions in hazardous
wastes entering combustion feed streams through process changes are
significant enough to warrant granting an extension.
A clear demonstration that reductions of hazardous wastes
entering combustion feed streams are not shifted as increases in
pollutants emitted through other regulated media.
A demonstration that the design and installation of
process changes, which include waste minimization measures, and other
measures that are necessary for compliance cannot otherwise be
installed within the three year compliance period.
These factors will provide a degree of consistency, while still
allowing flexibility among EPA Regional offices and approved States, in
the use of this innovative regulatory approach. EPA will also provide
separate guidance that provides examples of how to apply the factors to
consider and additional information that will be helpful to government
and regulated entities. For example, the guidance will provide examples
that will help gauge whether the magnitude of proposed requests to
reduce hazardous wastes entering combustion feed streams through
process changes are significant enough to warrant granting an
extension. For example, companies that commit to a 25% or greater
reduction in hazardous wastes entering combustion feed streams may be
more likely to be considered for an extension than companies that
commits to only a five percent reduction.
EPA anticipates that the guidance will contain other examples on
how to evaluate cases where a low percentage reduction may actually
reflects a significant improvement relative to previous significant
waste minimization achievements. The guidance will address how to
evaluate shifts from combustion feed streams to other regulated media,
such as wastewater effluents or other pollutant sources. EPA
anticipates the guidance will address assuring that the proposed
process changes that include waste minimization measures are critical
path steps toward compliance, and not process improvements that have
little to do with reductions of hazardous waste feed streams, and could
otherwise have little impact on compliance. Waste minimization measures
that are not on a critical path toward compliance or that do not have a
direct impact on reducing or eliminating hazardous waste streams
entering combustion feed streams are not good candidates for a one year
extension. Finally, EPA anticipates the guidance will include a list of
states that have approved part 70 permit programs, a list of states
that operate waste minimization technical assistance programs, and a
list of States that have mandatory or voluntary waste minimization
planning programs.
EPA also points out that companies that choose to apply for a one
year extension for waste minimization purposes may wish to coordinate
the development of compliance extension applications with the
development of ``public regulatory notifications of intent to comply,''
contained in today's rule, since much of the developmental work for the
two actions should be nearly identical.
In the comments received, several companies and states said that,
in some cases, even the three year compliance period plus a one year
extension would not be adequate time to design, and install waste
minimization measures or additional combustion or treatment measures
necessary to ensure compliance with the MACT standards. It may be
appropriate, under the circumstances described below, to grant
facilities who demonstrate that longer than three years plus a one year
extension is necessary to implement waste minimization measures that
significantly reduce the amount and/or toxicity of hazardous waste
entering combustion feed streams additional time (i.e., longer than
four years). Reducing the amount of hazardous waste entering combustion
feed streams provides greater long-term levels of protection for public
health and the environment than other non-waste minimization/pollution
prevention measures that could be used to comply with the MACT
standard. Since facilities that need longer than three years or the
three year date plus a one year extension to meet compliance are
technically in violation (not including facilities that are granted a
one year compliance extension and meet compliance within the one year
extension period), EPA will require these facilities to enter into
written consent agreements/consent orders (CA/COs) to receive this
additional time. The process changes that include waste minimization
measures must clearly demonstrate the facility will achieve significant
reductions in the amount of

[[Page 24248]]

hazardous wastes entering combustion waste streams over what would have
otherwise have been combusted over the long term using combustion-based
compliance alternatives installed within the three year compliance
period (or three years plus a one year compliance extension). EPA
encourages facilities to consider undertaking longer-term waste
minimization compliance approaches, subject to limitations proposed
today. EPA will consider such requests using its enforcement discretion
and the principles articulated in the Agency's ``Policy on Encouraging
Self-Policing and Voluntary Correction'' (60 FR 66706, December 22,
1995) (i.e., the ``Audit Policy''). Within this context, EPA may, in
certain cases, consider a reduction of penalties for facilities that
are able to install compliance solutions that demonstrate significant
reductions in hazardous wastes entering combustion feed streams, but
need additional time beyond that allowable under the regulations.
To qualify for this special consideration for additional time, a
regulated entity would have to submit a written request that contains
the information listed below. Facilities must submit requests to the
EPA Regional Office that has oversight for their facility within one
year after the MACT standards for this rulemaking are promulgated. The
request would include:
An explanation of why the facility cannot reasonably
implement their proposed process changes that include waste
minimization measures within four years from the date of the
promulgation of the MACT standards.
An explanation of how the facility's proposed process
changes (that include waste minimization measures) will achieve greater
reductions in quantity and/or toxicity of hazardous wastes entering
combustion feed streams. The proposed reductions must be significant.
EPA will make these determinations on a case-by-case basis.
An explanation of how the waste minimization/pollution
prevention measures are necessary to achieve compliance with the MACT
standards (i.e., waste minimization measures which reduce hazardous
wastes entering combustion feedstreams must be shown to have a direct
impact on the subsequent design, installation and testing of combustion
or other treatment measures necessary to achieve and go beyond
compliance standards), and a schedule for implementation of the
proposal.
A waste minimization facility plan. This plan must follow
EPA's ``Pollution Prevention Facility Planning Guide'' (May, 1992; NTIS
# PB92-213206), or, if the facility is located in a State that requires
mandatory waste minimization planning, the form of waste minimization
planning required by that State.
Regulated entities must demonstrate a clear intent to achieve
compliance in a timely fashion by entering into a consent agreement/
compliance order with EPA as soon as they exceed the allotted time
provided by the regulations (including any regulatory extension). EPA
would then exercise its enforcement discretion to treat a facility's
failure to achieve compliance by the regulatory deadline as a violation
that can receive penalty mitigation under the Agency's Audit Policy.
Under the Audit Policy the Agency may give up to a 100% reduction in
the gravity based component of potential penalties. To qualify for
eliminating the gravity-based penalty a facility will have to show that
it has a compliance management program that meets the criteria for due
diligence under the Audit Policy. Otherwise, the facility may qualify
for a 75% reduction of the gravity component of the penalty. EPA will
provide examples of past cases in the supplemental guidance noted
earlier in this section.
EPA realizes that some waste minimization compliance measures may
be more cost effective than combustion based approaches. EPA will
retain its discretion to recover any economic benefit gained as a
result of noncompliance. This will ensure that facilities that delay
compliance for a specific period of time do not receive an economic
benefit during the period of non-compliance over regulated entities
that do comply within the regulatory deadline. For example, EPA may
recover the economic benefit a company receives by delaying capital
expenditures for modifying their manufacturing process to meet the new
compliance standards. EPA may exercise its discretion in appropriate
circumstances to choose the lower figure between: (1) the company's
pollution prevention/waste minimization expenditures, and (2)
expenditures the company would have incurred implementing other methods
to come into compliance, when calculating economic benefit during the
period of non-compliance with the new regulatory standards. EPA will
also use its enforcement discretion to waive recovery of insignificant
amounts of any economic benefit resulting from a facility's delayed
compliance.
EPA is also encouraging companies to pursue waste minimization
measures in an expansion of the provision in the Clean Air Act
regulations that requires facilities to submit an early notification
that they intend to comply with the MACT standards as they become
effective (usually about 2-3 years after the notification is
submitted). The expansion, called a public regulatory notifications of
intent to comply, would require facilities to include substantially
more detail in this notification on: (1) What they have considered
doing to meet the MACT standards (particularly with respect to waste
minimization); and (2) how they have decided to proceed. This expanded
notification would be sent not only to the regulatory agency, but would
also be made available to the local community. In addition, the
facility would be required to hold an informal meeting with the local
citizenry to discuss the notification. However, regulatory agency
review and approval of the notification is neither mandated nor
expected. This approach would harness the power of public opinion to
urge facilities to consider waste minimization alternatives to end-of-
pipe ways of meeting the MACT standards. This approach is described in
detail elsewhere in today's NODA for public comment.
EPA requests comment on the extent to which the proposed one year
compliance extension, the proposed opportunity for companies to enter
into consent agreements/consent orders for periods that extend beyond
four years, and the PRNIC approach provide companies with appropriate
incentives to pursue waste minimization measures to achieve compliance.

VI. Permit Requirements

A. Coordination of RCRA and CAA Permitting Processes
In the NPRM, EPA proposed to place the final MACT standards in 40
CFR Part 63 and reference those standards in 40 CFR Parts 264 and 266
(61 FR at 17451). Under this proposal the standards would only be
written out in the CAA regulations, but they would legally be part of
both the CAA and RCRA regulations. Thus, both programs would have an
obligation to address the standards in permits issued under their
authority. EPA proposed this approach to provide the maximum amount of
flexibility for state permitting authorities to coordinate the issuance
of permits and enforcement activities in a way which most effectively
addresses their particular situation.
After reviewing the NPRM comments, there is some question on
whether the proposed approach will provide the maximum amount of
flexibility to the

[[Page 24249]]

state permitting authorities. The proposed approach would still require
in most cases at least two different permitting authorities to review
the air emission standards in a permit. Since under the original
proposal the standards would be in both the RCRA and CAA regulations,
permit writers from each program might be required to address them to
some degree in a permit under that program, either by writing them
directly in the permit or by referencing them from the other permit.
The proposed approach might not have given states the flexibility to
implement the new standards under a single regulatory program. Thus,
the proposed approach would result in duplicative permitting actions in
many cases.
Commenters had several other concerns with an approach where the
air emission standards are incorporated into two permits. One major
problem described by commenters is that the overlapping permit
conditions of the Title V and RCRA permits would be subject to two
separate permit modification procedures, administrative appeals
procedures, and potentially separate judicial procedures as well. The
Agency now believes that this outcome could be needlessly duplicative
and unwieldy, and therefore not consistent with the Agency's intent to
simplify permitting.
Additionally, commenters were concerned that the proposed approach
would have allowed for dual enforcement scenarios where enforcement
actions under both statutes would be brought against the facility for a
single violation. In the NPRM, EPA stated that the Agency did not
expect to enforce under both permits (61 FR at 17452). However,
commenters noted that this statement did not restrain the states from
initiating dual enforcement actions, or citizens from initiating dual
citizen suits.
Codifying the MACT standards in only one place in the regulations
(unlike the proposed scheme) may actually provide states the greatest
flexibility in the way they issue permits and prevent duplication of
effort. Although the standards would be codified under one statute,
states could decide which program they want implementing the standards.
A state would be free to decide, for example, to have its RCRA staff
implement a set of CAA standards. Another approach would be for a state
to decide under which state statute to adopt the MACT standards based
on which part of their program they wish to implement the standards.
For example if EPA places the MACT standards in part 63 only (see
below), a state could still decide to adopt those standards under their
state solid waste statute and implement the standards through their
RCRA hazardous waste program, depending on how their state solid waste
statute is written. The basic premise in this approach is that it is
not significant to EPA, nor to proper implementation of RCRA or CAA,
under what statute a state adopts a RCRA or CAA regulation.
EPA particularly would like to take comment on this issue. Do
states believe they can decide under which program to implement the
MACT standards if they are only placed in Part 63? EPA is concerned
that states be allowed to implement the standards through either their
CAA or their RCRA program, whichever works best for their particular
situation.
Currently, EPA is considering placing the MACT standards only in 40
CFR part 63 and relying on the air program implementation scheme,
including the Title V permitting program, to bring facilities into
compliance with the new standards. This approach (as opposed to the
converse--placing the standards only in the RCRA regulations) is the
only approach that appears feasible to allow the standards to be
codified in only one place in the regulations. The Agency would rely on
the integration provision of RCRA section 1006(b)(1) to defer RCRA
controls on these air emissions to the part 63 MACT standards. (The CAA
does not have a similar integration provision which would allow
deferral of CAA requirements to RCRA regulations.)
We emphasize, however, that under this approach, there would still
be a need for a RCRA permit at HWC facilities, to address any other
RCRA units on site, and to address RCRA regulations which apply to all
types of RCRA facilities and which are not duplicated under CAA. For
example, a permit will be required to address hazardous waste storage
units that hold the waste prior to combustion. As with all RCRA
permits, the permit would require compliance with the standards in 40
CFR part 264 (including general facility standards, preparedness and
prevention requirements, contingency planning and emergency procedure
requirements, manifesting requirements, recordkeeping and reporting
requirements, releases from solid waste management units requirements,
closure and post-closure requirements, financial requirements,
corrective action requirements, storage requirements, materials
handling requirements, and air emissions standards for process vents,
equipment leaks, tanks, and containers). The omnibus provision of RCRA
Section 3005(c)(3), codified at Sec. 270.32(b)(2), which provides for
additional permit conditions as necessary at a particular site to
protect human health and the environment, would also need to be
addressed in the RCRA permit, with respect to the combustor and other
activities at the facility. (This issue is discussed further in the
next section.) Among other consequences, this means that the current
program of processing RCRA HWC permits will continue until EPA
finalizes any program changes. It remains a high priority to bring all
HWC under full Part B permits as soon as possible.
Although the RCRA permit would not need to duplicate the MACT
controls contained in a Title V permit, there will typically be a
number of waste management activities associated with the combustion
unit that would need to be addressed in the RCRA permit (and not the
Title V permit), such as materials handling (feed and residues) and
combustor-specific (but not MACT-related) waste analysis requirements
and feed restrictions. If, as under the original proposal, the Agency
decides to retain the DRE standard in the RCRA regulations, then DRE
would also need to be addressed in the RCRA permit.
The discussion above describes one approach the Agency is
considering for the final rule. If this approach were adopted, it would
establish how EPA would implement the new MACT standards where the
Agency has permitting jurisdiction. However, in many cases, states are
delegated RCRA and CAA authority. It would therefore be up to the state
program to decide how best to implement the MACT standards given the
particular authorities of the state. The approach described today may
be better suited to provide greater flexibility for state approaches,
whether the State prefers to rely primarily on the MACT and Title V
permit process or the RCRA permit process to impose the new standards.
The Agency recognizes that in many cases facilities will already
have a RCRA permit in place when the MACT standards become effective.
This situation raises the question of what happens to RCRA permit
conditions related to combustor air emissions.
From an overall standpoint, it is expected that the MACT standards
will be more stringent than many current RCRA regulations and permit
conditions. However, at some individual sites, certain RCRA permit
conditions may be more stringent than the corresponding MACT emissions
standards. Some potential reasons why such a situation would occur are
because the RCRA permit condition is

[[Page 24250]]

based on a site-specific risk evaluation under the BIF rule or the
omnibus provision; because the MACT standard is in a different format
than the permit condition (e.g., a mass emission rate or removal
efficiency format in a RCRA permit vs. a concentration-based standard
for HCl under MACT) and at that particular site the RCRA format yields
more stringent control; because, in the case of CO limits in early
incinerator permits, the RCRA permit limit was based on levels during
the trial burn; or because the facility was one of the lower emitters
in the standards development MACT pool.
The Agency's overall intent is for the MACT standards to replace
the RCRA air emissions standards for hazardous waste combustors.
Therefore, where the Agency has permitting jurisdiction, the RCRA air
emissions permit limits for HWCs, with the exception of site-specific
risk-based limits, would be deleted from RCRA permits when the MACT
standards become operational. In the case of site-specific risk-based
limits, based either on the BIF metals and HCl/Cl2 requirements or
omnibus authority, these limits would remain in RCRA permits to satisfy
the protectiveness requirement of RCRA section 3004 (a) and (q). As
with EPA issued permits, in authorized states any site-specific risk-
based limits would need to be retained where necessary to satisfy RCRA
protectiveness requirements. Since authorized states are allowed to be
more stringent, states will determine, in the process of deciding
whether to delete old RCRA-based regulations and in the permitting
process, whether to keep or delete more stringent permit conditions
which are not based on a site-specific risk finding.
EPA would like to take comment on the approach of placing the MACT
standards only in the part 63 regulations, and deferring the RCRA
standards, as described above.
B. Permit Process Issues
As discussed above, the Agency is considering an approach of
placing the MACT standards only in 40 CFR part 63 and using RCRA
1006(b) authority to defer RCRA permitting to the Title V permitting
program for the air emission standards only. This approach raises the
issues of how and when the permitting authorities should modify
existing RCRA permits to remove the air emission standards. 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 emission limitations which are covered in
the Title V permit. Another option is to modify the RCRA permit at the
time the facility submits their comprehensive performance test results.
However, it is beneficial to wait until the test results are reviewed,
approved, and written into a Title V permit before deleting any RCRA
permit conditions because of the greater level of Agency and public
review that occurs during the permit process. The Agency would like to
take comment on this issue. At what point should the RCRA permit be
modified to remove air emission standards? How should the switch-over
to the new permitting system occur? Note that irrespective of when the
Title V permit is issued/modified, the MACT standards and associated
operating limits become enforceable according to the schedule in the
final rule.
After the compliance date for the final rule, but before the RCRA
permit is modified to remove any air emission limitations, there will
be a period where a facility will have both a RCRA permit that
addresses air emissions and either: (1) A precertification of
compliance document with applicable operating conditions that they have
submitted; or (2) a Title V permit which also addresses air emissions.
Note, the RCRA permit will continue to apply until such time that it is
modified to remove any air emission limitations. The precertification
of compliance document or Title V permit will not automatically
supersede RCRA permit conditions as a matter of law. The more stringent
conditions will govern.
C. Omnibus and RCRA/CAA Testing Coordination
As discussed in the preamble to the proposed rule (61 FR at 17371),
EPA currently has a national RCRA policy of strongly recommending to
all federal and state RCRA permit writers that, under the omnibus
provision of RCRA section 3005(c)(3), site-specific risk assessments
(SSRAs) generally be performed as part of the RCRA permitting process
to determine whether additional conditions are necessary to protect
human health and the environment. The results of these risk assessments
are then used to set protective permit conditions. Under the new
permitting scheme that the Agency is considering (placing the MACT
standards only in 40 CFR part 63), the Agency is considering when the
RCRA omnibus provision would continue to be used--for example, to
require a site-specific risk assessment--and the timing of the RCRA
omnibus finding in relation to the Title V permit issuance/
modification.
As discussed in the NPRM, the Agency has indicated a preference for
modifying our current policy of recommending that a site-specific risk
assessment (SSRA) be performed during permitting at hazardous waste
combustors in most cases (61 FR at 17372). Depending on the scope and
level of the final MACT standards, this policy may need to be re-
evaluated. For at least some facilities, there might still be
sufficient cause to perform a SSRA under the RCRA omnibus permitting
authority.
Thus, the Agency is also considering the timing issue of whether a
RCRA omnibus finding would be expected to occur at the same time as the
Title V permitting decision (or the Title V permitting modification
decision, if this is more appropriate, since some of these units will
most likely already have Title V permits). The Agency expects that many
of the trial burns to support SSRAs will already be completed prior to
the effective date of the MACT rule, and would not need to be repeated
provided none of the resulting emissions limitations are relaxed based
on the MACT rule. For facilities where trial burns for risk assessments
have not been performed, a RCRA omnibus determination as to whether a
SSRA is needed can be made in most cases before the comprehensive test
protocol is finalized. This situation would allow the MACT
comprehensive test protocol and RCRA trial burn plan to be coordinated
with respect to sampling and analysis procedures and operational
protocols. However, the Agency does not plan to hold up comprehensive
performance test approval or the Title V permit process (modified or
new permits) to accommodate a RCRA omnibus finding.
If it were not possible to make the RCRA omnibus determination in
sufficient time to allow coordinated emissions testing, then a separate
RCRA trial burn might be necessary. This separate test event would
increase the costs to the facility and require more oversight by the
permitting authority. After allowing for additional time to perform a
SSRA, the findings of the risk assessment could then be used to
establish site-specific standards which, in turn, might require a
review of the Title V permit and its associated operating limits/
standards.
It should also be noted that if the DRE standard is retained under
RCRA (see discussion in Section III.A.), these same testing
coordination issues apply to DRE testing. (At sites where SSRAs are to
be performed, it is expected that DRE

[[Page 24251]]

testing and testing necessary to provide data for SSRAs will be
occurring at the same time.)
We invite comment on the workability of this approach for achieving
maximal coordination of the RCRA trial burns and omnibus findings with
the initial MACT comprehensive test and Title V permitting.

Part Four: Miscellaneous Issues

I. 5000 Btu per Pound Policy for Kiln Products

Current Agency policy exempts cement product (clinker) from cement
kilns burning hazardous waste from regulation as a hazardous waste
provided the fuel value of the hazardous waste exceeds 5000 Btu per
pound ⁶⁸. This allows cement kilns to burn high-Btu
hazardous waste for energy recovery purposes and still market the
clinker and the cement mix produced from the clinker as commercial
product free from any Subtitle C concerns. The Agency has already
provided a clarification (53 FR 31198, August 17, 1988) that the
regulations for ``waste derived products'' at Sec. 266.20 do not apply
to products from processes using hazardous waste (HW) fuels, unless
these processes also use hazardous wastes as ``ingredients'' in a
product destined for land application (i.e., the product must
``contain'' the HW as an ingredient to be covered by Sec. 266.20) or
burn hazardous waste for destruction. To implement this regulation, the
Agency has used Btu values of a waste as a proxy to determine whether
contaminants in the HW fuels will or will not be deemed to transfer to
the product (i.e., become ingredients). Over time, many commenters have
submitted data and have suggested that the heat content of a waste is
an indirect and imprecise way of identifying whether materials should
be subject to the provisions of Sec. 266.20 (hazardous wastes used in a
manner constituting disposal).
---------------------------------------------------------------------------

\68\ Wastes with energy value greater than 5000 Btu may
generally be said to be burned for energy recovery, since this is
the Btu value of low grade fuels. 48 FR 11157-59 (March 16, 1983).
However, lower energy wastes could conceivably be burned for energy
recovery in industrial furnaces, such as cement kilns, or in
industrial boilers due to these devices' general efficiency of
combustion. Id. At 11158. Thus, the 5000 Btu level is not an
absolute measure of burning for energy recovery (i.e., a rule),
particularly when industrial furnaces and industrial boilers are
involved.
---------------------------------------------------------------------------

The Agency has been interested for some time in considering whether
and how to change the existing Btu approach. For example, 60 FR 7376
(February 7, 1995) discusses a possible exclusion of clinker from the
derived-from rule, even when cement kiln dust is introduced in the
feed. EPA has also discussed with CKRC the narrower issue of whether
the 5000 Btu/lb energy value level reliably predicts whether toxic
contaminants would more likely partition to the clinker and ultimately
the cement product. Some from industry have suggested that a facility
that agrees to limit waste feed metals to their ``historic average''
could be exempted from the 5000 Btu/hr policy. The rationale is that
even if the facility took lower Btu waste, they would not be taking
higher quantities of metal waste than currently, at least on the
average. This would address EPA's concern about allowing an increase of
metals in HW fuels burned by cement kilns if the 5000 Btu restriction
were abandoned.
Today, without our endorsement at this time, the Agency is offering
this concept and some potential variations for public comment. The
Agency is interested in the possible ramifications and requests
comment, particularly with respect to limiting the concentrations of
metals in cement products from cement kilns burning hazardous waste. To
take advantage of such a policy, a facility would have to establish a
baseline of metals feed in the hazardous waste (for example, the
average of the previous three years) and then agree to enforceable
permit conditions limiting metals feedrate levels to that average plus
one standard deviation. Presumably, enforceable restrictions on metal
feed rates should control metal partitioning to clinker and CKD much
more effectively than would the Btu limit and ensure that these
materials would not contain an increase in toxic metal constituents
from the hazardous waste used as fuel. Also, metal feed limits based on
a historical average would appear to be more stringent than the current
BIF metal feed limits, which are set on a health basis considering
direct inhalation of metals emissions. (In other words, as discussed in
earlier sections of this notice, cement kilns are generally feeding
metals far below allowable BIF limits.)
EPA seeks comment on allowing cement kilns (and LWAKs) the option
of complying with the following, which is only partly based on the
suggestions discussed with cement kiln representatives, with some
additions:
An owner or operator of a cement kiln burning hazardous
waste would be allowed to burn hazardous waste with any Btu content,
provided the owner or operator agrees to enforceable hazardous waste
feed operating limits on metals of concern (see below);
These metals feed limits would be set at levels that would
ensure, at least on an annual basis, that metals on a mass basis do not
increase over current levels, which are substantially less than those
allowable under BIF (and sources would, of course, remain subject to
stack emission standards to control the emission of metal HAPs);
Feed limits would have to be established for each of the
following twelve metals: antimony, arsenic, barium, beryllium, cadmium,
chromium, cobalt, lead, nickel, selenium, thallium, and vanadium;
Sampling and analysis would be conducted as often as
necessary to document that the metals levels are below the limits and
included in the facility's waste analysis plan required by 40 CFR
264.13; and
Results of the analysis would have to be available for
public inspection.
Also, the Agency is considering a variation of this option, under
which kiln operators would have to achieve specified percentage
reductions of the total quantity (on an aggregate basis) of the
following metals in their wastes combusted: antimony, arsenic, barium,
beryllium, cadmium, chromium, cobalt, lead, nickel, selenium, thallium,
and vanadium. EPA chose these particular metals based on their
potentially high human health and ecological risk in conjunction with
their significant tendencies to persist in the environment and
accumulate in living tissue. If generators reduce metals in wastes over
time, holding kilns to the average of the past three years may actually
allow increased burning of certain metal-bearing streams. This is
because other streams may contain less metals. In contrast, commitments
to reducing metals below baseline limits would ensure that progress
continues in waste minimization. EPA requests comments on this option,
including information about: (1) The prevalence and distribution
throughout industry sectors of waste streams bearing these metals sent
to combustion, and (2) opportunities for generators to reduce these
metals in wastes sent to combustion by means of source reduction during
generation.
EPA requests comment on the impact of imposing limits on metals
concentration on waste streams combusted in cement kilns. EPA raises
these questions:
How much hazardous waste now sent to cement kilns for
energy recovery would be likely to meet such metal level limitations?
Of the fraction of wastes that would ``fail'' a metals
limit, would generators of waste now sent to cement kilns reduce metals
concentrations in these wastes, using waste minimization and pollution
prevention, so that cement

[[Page 24252]]

kilns would continue to receive the same amounts of waste?
If no such action to reduce metals concentrations
occurred, would cement kilns reject high-metals hazardous wastes now
sent to cement kilns for energy recovery and would these wastes go
instead to incinerators?
The Agency also requests comment on the related issue of
appropriate metals reduction goals. EPA has identified a national goal
for waste minimization of the most persistent, bioaccumulative and
toxic hazardous constituents by 25 percent by the year 2000 and by 50
percent by the year 2005. See EPA's Waste Minimization National Plan
(Office of Solid Waste, November 1994). Consistent with this national
waste reduction goal for metals, EPA requests public comments today on
requiring aggregate percentage reductions for the twelve metals in
waste feed, as an alternative to holding cement kilns to the historical
average feed limits of the past three years and allowing no increases
over baseline limits. This approach would also further waste
minimization planning by offering kilns a reason to motivate the
generators supplying them with hazardous waste for combustion to
undertake waste minimization. In comments related to the role of waste
minimization in the MACT proposal, Molten Metal Technologies (MMT)
states that ``without drivers favoring pollution prevention and waste
minimization in the instant rulemaking, only minimal progress will be
made.'' MMT points out that economics conspire against pollution
prevention and waste minimization since investment for compliance often
takes priority over investment for process modifications to reduce
waste generation and since corporate rate-of-return thresholds may
``squash'' pollution prevention and waste minimization initiatives.
Finally, the Agency requests comment on whether additional nonmetal
constituents (e.g., chlorinated organics) should also be identified for
similar reductions as part of this approach.

II. Foundry Sand Thermal Reclamation Units

A. Background
Foundry operations can generally be classified as either ferrous or
nonferrous, depending on their primary feed materials. Both types of
foundries use large amounts of sands for their metal molds. Over time,
the sands become contaminated with the metals being used, as well as
with certain binder materials. Nonferrous foundries (i.e., brass, lead,
etc.) sometimes generate spent sands that exhibit the Toxicity
Characteristic (40 CFR 261.24) for lead or cadmium. (The Agency has
indicated concerns with certain sand treatment methods. See 62 FR
10004, March 5, 1997.) These sands can be physically processed to
remove contaminants for continued use, resulting in less sand use for
the foundry, and less need for disposal of the sands. Interest has also
been expressed in using thermal processing or reclamation units (TRUs)
to clean the sand for continued use. TRUs may represent a significant
waste minimization technology for the foundry industry.
The TRUs remove contaminants primarily by combusting the organic
binder materials in the sand. These organic materials are generally
wax-like materials, synthetic or natural (e.g., clays, phenols, etc.).
Air emissions concerns would include lead, cadmium, and particulate
emissions, as well as products of incomplete combustion. These units
are identified as industrial furnaces under 40 CFR 260.10 as a type of
``foundry furnace'' and are subject to regulation under 40 CFR part
266, subpart E (the ``BIF rules'') when they burn hazardous
waste.⁶⁹ When the Agency developed subpart E, however, we
did not consider whether TRUs would be appropriately controlled under
those standards. The Agency created a special exemption for metal
recovery furnaces under Sec. 266.100(c) and also proposed a special
exemption for petroleum catalyst recovery units (see 60 FR 57780;
November 20, 1995). In these two cases, we found that the BIF rules
would not appropriately control the units in question, i.e., any air
emissions hazards might be more appropriately controlled under
standards specially designed for those units under either RCRA or CAA.
Under RCRA Section 1006, an important consideration for the Agency is
to avoid duplication to the extent practical between the two Acts.
Also, as noted above, TRUs may achieve significant waste minimization
benefits, an important consideration under RCRA.
---------------------------------------------------------------------------

\69\ Another potential reading of the Section 260.10 definition
is that ``foundry furnaces'' only applies to a furnace that burns a
primarily metal-bearing material. Under this reading, TRUs could not
be industrial furnaces because they burn sand with only contaminant
levels of metals. However, since TRUs are closely associated, both
physically and functionally, with the primary metal processing
functions of a foundry, they are appropriately classified as
industrial furnaces subject to part 266, subpart E.
---------------------------------------------------------------------------

B. Deferral and Variance Options for Consideration
The Agency is presently developing MACT controls under the CAA for
foundries. Although at this time it is not clear to what extent TRUs
would be subject to MACT controls, representatives from the foundry
industry have suggested that, as the new MACT rules are implemented,
all foundries with TRUs will be required, as a practical matter, to
install MACT controls on the TRUs. Among the reasons cited are that
vendors of TRU technology will have to design for situations under MACT
control, and state air officials will incorporate the MACT technology
in permits for foundries as a matter of course.
Although EPA has no way to predict whether this scenario would come
to pass, there are obvious advantages to controlling TRUs processing
sands that exhibit the TC under MACT standards, as opposed to under the
BIF rules. These advantages include administrative simplicity and
maximum flexibility for implementing agencies. EPA requests comment on
the following two approaches to ensure appropriate controls for TRUs:
1. Deferral option. Given the developments under the CAA discussed
above, and also in light of the potential waste minimization benefits,
EPA requests comments on appropriate control schemes for TRUs burning
hazardous foundry sands. Specifically, comments are requested on a
deferral of BIF applicability, similar to the existing provision for
metal recovery furnaces and proposed provision for petroleum catalyst
recovery units. This would allow development of the foundry MACT, and
potentially the eventual application of these controls to TRUs
processing sands that exhibit the TC. Under such an approach, EPA would
place an exemption in Part 266, Subpart E, identifying foundry TRUs as
an exempt BIF, and a one-time notice would be required as is now
required for metal recovery furnaces under Sec. 266.100(c)(1)(I).
2. Variance from definition of solid waste option. TRUs appear to
be integral to foundry operations. They are located at the foundry
site, operated by the foundry, and the sand being processed and
returned to the foundry operation is essential in the manufacturing
operation. The time periods between when a spent sand is generated and
when it is processed and returned is typically a matter of hours. In
fact, TRUs may reduce the need to store spent sands for processing and
may thereby reduce fugitive emissions of the sands

[[Page 24253]]

that might result from physical processing. Given that a sand appears
integral to foundry operations and TRUs can greatly improve the
efficiency of sand use, EPA could conclude that even without any rule
changes, foundry operators may be eligible for a variance from the RCRA
definition of solid waste under the variance provisions found at 40 CFR
260.30(b), 260.31(b), and 260.33.
Under these variance provisions, EPA (or an authorized State) may
grant a variance from the definition of solid waste for materials that
are reclaimed and then used as feedstock within the original production
process in which the materials were generated if the reclamation
process is an essential part of the production process. This evaluation
is guided by a number of criteria found at Sec. 260.31(b). While
foundries certainly can and do operate without thermally processing
their sands, and so TRUs are not literally ``essential'', as summarized
above the units do in fact greatly increase efficiency of sand use,
which is an essential raw material of foundry operations. Also, the
TRUs are physically proximate, and integrated into the foundry's
operations. Emissions from the TRUs are often ducted into emission
control devices used for the foundries' main production activities. As
such, the Agency could view sands being processed in TRUs as
potentially eligible for the variance under 260.31(b) ⁷⁰.
EPA (or the State) would still have to weigh the factors in paragraph
(b) on a case-by-case basis to determine if the variance should be
granted. For example, paragraph (b)(3) requires an examination of how
the sands are handled to ensure that losses are minimized before
reclamation. Also, paragraph (b)(8) allows consideration of ``other
factors'' as appropriate, and in this case, air emissions controls for
the TRU would be appropriately considered before granting a variance.
As discussed above, controls may be installed as part of the MACT
process, or simply due to state or local air pollution laws. The Agency
would expect that as a minimum, emissions of particulate matter would
have to be limited to control lead emissions, and given the organic
binder compounds being introduced to the units, limits on and
continuous monitoring of indicators of efficient combustion, such as CO
and/or HC, would seem appropriate. Under this approach, the Agency
might or might not develop special standards for TRUs under RCRA or the
CAA. The case-by-case approach might enable EPA and the States to
oversee the units without the need for federal standards.
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\70\ The Agency notes that, typically, a variance from the
definition of solid waste under 260.31(b) would apply at the point
of generation (e.g., in this case, the point where the spent sands
are removed from the casting forms). Also, typically, when such a
variance is granted, the variance is only applicable to those
secondary materials that meet the conditions of the variance (e.g.,
the variance would not include secondary materials that are not
reused in the production process).
The normal and efficient flow of materials at facilities with a
TRU may involve the processing of all of the spent sand generated.
However, after recovery of the sand, insubstantial amounts of sands
that are processed by the TRU may be found to be unusable again as
foundry sand, and so may be discarded. While treatment and disposal
of the spent foundry sand is clearly not the intent of the TRU,
``treatment and disposal'' would be the regulatory status of any
hazardous secondary material that is processed such that it is no
longer hazardous and then discarded, given the most straightforward
reading of the regulations.
Nevertheless, the Agency believes that because the TRU is
typically integrated into the facility's operations, and the flow of
spent foundry sand into the TRU becomes a standard operating
procedure, the incidental discard of an insubstantial amount of
spent foundry sand should not overshadow the basic purpose of
Sec. 260.31(b) to grant a variance from the definition of solid
waste to materials that are reclaimed and reused in the production
process, where such reclamation is, in effect, an integral step in
the flow of production. Thus, the Agency asserts that, assuming all
other conditions of the Sec. 260.31(b) variance are met, the fact
that a relatively insignificant amount of spent foundry sand is
discarded would not negate a variance granted to spent foundry sand,
or require a treatment permit for the TRU.
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III. Status of Gaseous Fuels Generated From Hazardous Waste Management
Activities

The proposed rule included a proposed exclusion from subtitle C
jurisdiction for certain synthetic gas fuels derived from hazardous
waste treatment activities (61 FR at 17465). Some commenters stated
that synthesis gas fuels are beyond EPA's regulatory authority because
they are uncontained gases, and further stated that EPA had failed to
set out any explanation for its potential jurisdiction over these
synthesis gas fuels (which jurisdiction EPA proposed to relinquish
provided the syngas met designated specifications).
The type of syngas discussed in the proposal results from thermal
reaction of hazardous wastes, which reaction is optimized to break
organic bonds and reformulate the organics into hydrogen gas and carbon
monoxide. Id. This resulting gas can be used as a fuel at manufacturing
facilities.
EPA has broad statutory authority to regulate fuels produced from
hazardous wastes. RCRA section 3004(q)(1); see also Horsehead Resource
Development Co. v. Browner, 16 F. 3d 1246, 1262 (D.C. Cir. 1994)
(broadly construing this authority). The fact that syngas (by
definition) is a gas, rather than a solid or liquid, does not appear to
raise jurisdictional issues. It is still produced from the hazardous
wastes that are being processed thermally. See Sec. 261.2(c)(2)(A) and
(B) (defining such materials as solid wastes). EPA believes its
authority to be clear under these provisions, but will consider further
comment on the issue.⁷¹
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\71\ See also 50 FR 49164, 49171 (Nov. 25, 1985); 52 FR 16982,
17021 (May 6, 1987); and 56 FR 7134, 7203-04 (Feb. 21, 1991) which
discuss this question, although inconclusively.
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IV. Regulatory Flexibility Analysis

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 be performed 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 in the
Act, are only those ``businesses, organizations and governmental
jurisdictions subject to regulation.''
In preparation of the proposed rule, EPA 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, EPA identified 13 firms which may be small entities.
That analysis also determined that the proposed rule was unlikely to
result in detrimental impacts to small businesses. This conclusion was
derived from two important findings:
First, few combustion units are owned by businesses that meet the
SBA definition. Among those that are considered small (based on number
of employees), over one-third were found to have gross sales in excess
of $50 million per year. Furthermore, available data indicate an
ongoing industry trend toward consolidation, or market exit.
Second, small entities impacted by the rule, were found to be those
that currently burn very little hazardous waste, and hence face very
high cost per ton burned. These on-site facilities are likely to
discontinue burning hazardous waste and dispose off-site, rather than
comply with the proposed rule. Based on available data, EPA found that
the incremental cost of alternative disposal associated with
discontinued burning of such waste would not exceed 0.10 to 0.20
percent of annual corporate gross revenues. Furthermore, currently
viable commercial small business facilities affected by the proposal
were found to remain profitable.

[[Page 24254]]

The above findings indicate that the proposed rule is expected to
have overall negligible impacts on small entities. The Agency is
currently refining and expanding its analysis of small entities and
makes no conclusions beyond those presented for the Proposal.

Dated: April 22, 1997.
Elizabeth Cotsworth,
Acting Director, Office of Solid Waste.
[FR Doc. 97-11155 Filed 5-1-97; 8:45 am]
BILLING CODE 6560-50-P}}

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Document Information

Published:: 05/02/1997
Department:: Environmental Protection Agency
Entry Type:: Proposed Rule
Action:: Notice of data availability and request for comments.
Document Number:: 97-11155
Dates:: Written comments must be submitted by June 2, 1997.
Pages:: 24212-24254 (43 pages)
Docket Numbers:: FRL-5818-9
PDF File:: 97-11155.pdf