[Federal Register Volume 62, Number 249 (Tuesday, December 30, 1997)]
[Proposed Rules]
[Pages 67788-67818]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 97-33740]
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ENVIRONMENTAL PROTECTION AGENCY
40 CFR Parts 60 and 63
[FRL-5941-4]
Total Mercury and Particulate Continuous Emissions Monitoring
Systems; Measurement of Low Level Particulate Emissions; Implementation
at Hazardous Waste Combustors; Proposed Rule--Notice of Data
Availability and Request for Comments
AGENCY: Environmental Protection Agency (EPA).
ACTION: Notice of data availability and request for comments.
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SUMMARY: This announcement is a notice of data availability and
invitation for comment on the following reports pertaining to total
mercury and particulate continuous emissions monitoring systems: DRAFT:
Total Mercury CEMS Demonstration, Summary Table, dated December 1997;
and DRAFT: Particulate Matter CEMS Demonstration, Volume I (with
appendices), dated December 1997. EPA proposed requiring these monitors
for hazardous waste combustors in the hazardous waste combustor
proposed rule published on April 19, 1996. In addition, this document
discusses topics for implementing particulate matter continuous
emissions monitoring systems at hazardous waste combustors.
Readers should note that only comments about new information
discussed in this document will be considered. Issues related to the
April 19, 1996, proposed rule and subsequent documents that are not
directly affected by the documents or data referenced in this Notice of
Data Availability are not open for further comment.
DATES: Written comments on these documents and this document must be
submitted by January 29, 1998.
ADDRESSES: Commenters must send an original and two copies of their
comments referencing Docket Number F-97-CS6A-FFFFF to: RCRA Docket
Information Center, Office of Solid Waste (5305G), U.S. Environmental
Protection Agency Headquarters (EPA, HQ), 401 M Street, SW, Washington,
D.C. 20460. Comments may also be submitted electronically through the
Internet to: rcra-docket@epamail.epa.gov. Comments in electronic format
should also be identified by the docket number F-97-CS6A-FFFFF. All
electronic comments must be submitted as an ASCII file avoiding the use
of special characters and any form of encryption. 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, OSW (5305W), 401 M Street,
SW, Washington D.C. 20460.
For other information regarding submitting comments electronically,
viewing the comments received, and supporting information, please refer
to the proposed rule (61 FR 17358 (April 19, 1996)). The RCRA
Information Center is located at Crystal Gateway One, 1235 Jefferson
Davis Highway, First Floor, Arlington, Virginia and is open for public
inspection and copying of supporting information for RCRA rules from
9:00 a.m. to 4:00 p.m. Monday through Friday, except for Federal
holidays. The public must make an appointment to view docket materials
by calling (703) 603-9230. The public may copy a maximum of 100 pages
from any regulatory document at no cost. Additional copies cost $0.15
per page.
FOR FURTHER INFORMATION CONTACT: For general information, call the RCRA
Hotline at 1-800-424-9346 or TDD 1-800-553-7672 (hearing impaired)
including directions on how to access some of the documents and data
referred to in this notice electronically. Callers within the
Washington Metropolitan Area must dial 703-412-9810 or TDD 703-412-3323
(hearing impaired). The RCRA Hotline is open Monday-Friday, 9:00 a.m.
to 6:00 p.m., Eastern Time.
The documents referred to in this notice are available over the
Internet. The documents can be accessed by typing the following
universal resource locator (URL):
http://www.epa.gov/epaoswer/hazwaste/combust/cems
This URL provides a home page through which all electronically
available documents can be downloaded. The Technology Transfer Network
(TTN) also provides a link to this page. CEMS information is available
on TTN at the following URL:
http://ttnwww.rtpnc.epa.gov/html/emtic/cem.htm
The home page contains links to the files that are available
electronically. The files are in an executable, compressed format to
facilitate
[[Page 67789]]
downloading. Once extracted, each compressed file may result in more
than one decompressed file. The reports are in Adobe
Acrobat, PDF format. The reader should note that
figures, diagrams, and appendices may not be available electronically
or may only be available in other formats.
For other information regarding the information contained in
Sections I, II, IV, and V of this notice, contact Mr. Scott Postma,
(5302W), Office of Solid Waste, 401 M Street, SW, Washington, D.C.
20460, phone (703) 308-6120, E-MAIL: postma.scott@epamail.epa.gov. For
information regarding Section III of this notice, contact Mr. H. Scott
Rauenzahn (5302W), Office of Solid Waste, 401 M Street, SW, Washington,
D.C. 20460, phone (703) 308-8477, e-mail:
rauenzahn.scott@epamail.epa.gov.
SUPPLEMENTARY INFORMATION: On April 19, 1996, EPA proposed revised
standards (herein referred to as ``the proposed rule'') for hazardous
waste combustors (HWCs, i.e., incinerators and cement and lightweight
aggregate kilns that burn hazardous waste). See 61 FR 17358. Comments
received from the public in response to the proposed rule are found in
RCRA docket F-96-RCSP-FFFFF.
A previous notice of data availability (NODA), published on March
21, 1997, gave the public the opportunity to review the Agency's
approach to demonstrating CEMS for HWCs. This previous NODA is herein
referred to as ``the first CEMS NODA'' or ``CEMS NODA 1.'' See 62 FR
13776. Comments received from the public in response to the first CEMS
NODA are found in RCRA docket F-97-CS3A-FFFFF.
Readers should note that a separate docket was established for this
document. See the Addresses section above for more information.
Table of Contents
I. Introduction and Background
II. The Hg CEMS Demonstration Tests
III. The PM CEMS Demonstration Tests
A. PM performance Specification (PS) 11 Levels
1. Revised Specification Levels for the Correlation
Coefficient, Confidence Interval, and Tolerance Interval
2. Data Availability
3. Data Quality Objectives: New Procedures to Appendix F of 40
CFR Part 60
B. Manual Method Accuracy
1. Modification of the Filter Recovery Process
2. Improved Sample Collection
3. Elimination of Contamination
4. Improved Sample Analysis
5. Comparison of M5 and M5i Method Precision
6. Paired Data
C. Transferability of These Demonstration Test Results to Other
HWC Sources
IV. PM CEMS: Implementation and Compliance
A. PM CEMS Compliance Schedule
B. PM CEMS Operating Parameter Limit
1. Introduction
2. Data Excluded from Calculating the PM CEMS Operating
Parameter Limit
3. Determining the Normality of the Data
4. Averaging Periods for the PM CEMS Operating Parameter Limit
5. Options for Calculating the PM CEMS Operating Parameter
Limit
a. Using rank statistics to calculate the PM CEMS-based
operating parameter limit at one, fixed averaging period
b. The traditional standard setting approach
6. Consideration of a Variance Procedure to Project a Higher PM
CEMS Operating Parameter Limit
a. HAPs for which PM control is necessary to ensure compliance
b. Projecting a higher PM CEMS operating parameter limit
considering the ratio of the standard to the measured level of a HAP
c. Ensuring that the higher projected PM CEMS operating
parameter limit does not exceed the MACT PM standard
d. Establishing revised operating parameter limits for the PM
control device corresponding to the higher projected PM CEMS
operating parameter limit
e. Implementing the variance
7. EPA's PM CEMS Testing to Identify a CEMS-Based Emission
Level Achievable by MACT-Controlled Sources
C. RCA Test Frequency
D. Extrapolating PM CEMS Calibration Data
1. Extrapolating Light-Scattering PM CEMS Calibration Data
2. Extrapolation of Beta-gage Calibration Data
E. Need to Calibrate to Twice the Emission Standard
F. Allowing PM CEMS to be Used In-lieu of Method 5 Tests
G. Waivers from the PM CEMS Requirements
1. Waiver of PM and Hg CEMS Requirements for Small On-Site
Incinerators
2. PM CEMS Waiver for Sources with Short Life-Spans
3. Other Sources
V. Other Issues Concerning CEMS and Test Methods for HWCs
A. Performance Specifications for Optional CEMS
B. Stack Sampling Test Methods
PART 60--STANDARDS OF PERFORMANCE FOR NEW STATIONARY SOURCES
I. Introduction and Background
In the proposed rule, EPA proposed that continuous emissions
monitoring systems (CEMS) be used for compliance with the HWC total
mercury (Hg) and particulate matter (PM) standards. See 61 FR at 17426
and 17435. To require CEMS for compliance the Agency, among other
things, must determine that the CEMS are commercially available and
have been demonstrated to meet certain performance specifications. To
make these determinations, the Agency tested various Hg and PM CEMS
being marketed in the U.S. and Europe. The first CEMS NODA described
the approach EPA is using to demonstrate the feasibility of PM and Hg
CEMS and requested comment on certain technical issues arising from
this program. This testing is now complete. Today the Agency is
providing notice of an opportunity to comment on the following
documents resulting from these CEMS demonstration test program: DRAFT:
Total Mercury CEMS Demonstration, Summary Table, dated December 1997;
and DRAFT: Particulate Matter CEMS Demonstration, Volume I (with
appendices), dated December 1997.
The remainder of this notice describes important information
bearing upon how the reports' results relate to EPA's approach to
demonstrating Hg and PM CEMS and how PM CEMS could be used for
compliance. Many of these issues were raised by commenters in response
to CEMS NODA 1 and the proposed rule. The reader is referred to the
referenced documents for specific information regarding the Hg and PM
CEMS demonstration test program and the comments cited here.
II. The Hg CEMS Demonstration Tests
EPA seeks comment on the document DRAFT: Total Mercury CEMS
Demonstration, Summary Table, dated December 1997, provided in the
above referenced docket for this NODA. This table summarizes results
from the Hg CEMS demonstration tests EPA conducted.
In summary, the Agency found certain aspects of the testing program
revealed substantial problems regarding the measurement of the Hg CEMS
accuracy and precision. EPA found it difficult to dynamically spike
known amounts of mercury (in the elemental and ionic form) and obtain
manual method and Hg CEMS measurements that agree at the test source.
As a result, the Agency now believes it has not sufficiently
demonstrated the viability of Hg CEMS as a compliance tool at all
hazardous waste combustors and should not require their use.
Nonetheless, EPA still believes Hg CEMS can and will work at some
sources but does not have sufficient confidence that all HWC conditions
are conducive to proper operation of the Hg CEMS tested. Facilities
should have the choice of using Hg CEMS if desired so long as the
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permitting agency approves on a site-specific basis the Hg CEMS and its
site-specific performance specifications. See a related issue in
section V.A. of this NODA regarding the implementation of optional
CEMS.
III. The PM CEMS Demonstration Tests
This section describes the report DRAFT: Particulate Matter CEMS
Demonstration, Volume I (with appendices), dated December 1997,
contained in the docket identified in the Addresses section, above. EPA
issued previous notices asking vendors to participate in this program
(see 61 FR 7232, February 27, 1996) and to allow the public to comment
on the Agency's approach to demonstrating these monitors (see 62 FR
13775, March 21, 1997). Since this could represent the first time EPA
requires PM CEMS for compliance at stationary sources, the technical
discussion contained in this section is expected to have general
applicability beyond sources that burn hazardous waste. In particular,
EPA invites comment from all parties concerning the following documents
attached to this notice: Method 5I for the determination of low level
particulate emissions; Performance Specification 11 for PM CEMS; and
Quality Assurance Requirements for PM CEMS.
A. PM Performance Specification (PS) 11 Levels
In CEMS NODA 1, the Agency stated it intended to loosen the
proposed PM CEMS Performance Specification (PS) 11 to reflect what was
achievable by the monitors during this demonstration test. The test was
designed to be a reasonable worst case investigation of what
performance (relative to the proposed PS11) the monitors could achieve.
Many comments received in response to CEMS NODA 1 stated that the
proposed performance specifications were not sufficiently stringent and
opposed loosening the specification levels.
Concurrent with the Agency's invitation in CEMS NODA 1 to comment
on our approach to demonstrate PM CEMS, EPA determined that much of the
variability in the calibration curves resulted from inaccuracies in
performing the manual method, Method 5 (M5). Since the fundamental
approach in PS11 involves correlating manual method results to PM CEMS
outputs, the PS11 statistical results reflected this variability in the
manual method. Consequently, EPA undertook a systematic effort to
identify and remove this error from the manual method measurement
process. Manual method improvements were developed and observed, and
performance specification results for the PM CEMS improved as a result.
(See a related discussion in section III.B, below, regarding these
improvements to the manual method.)
1. Revised Specification Levels for the Correlation Coefficient,
Confidence Interval, and Tolerance Interval
As a result of comments on CEMS NODA 1, EPA decided to accept a
slightly modified version of the more stringent International Standards
Organization (ISO) specification 10155 for PM CEMS. Four of the five PM
CEMS tested during the PM CEMS demonstration tests were able to meet
all three performance specifications (i.e., those for the correlation
coefficient (r), confidence interval (CI), and Tolerance Interval (TI))
at all three of the emissions levels discussed in the May 2, 1997, NODA
as alternatives to the proposed emissions standards (69 mg/dscm for
cement kilns, 50 mg/dscm for light-weight aggregate kilns, and 34 mg/
dscm for hazardous waste incinerators.) See 62 FR 24212 for a
discussion of those alternative emissions standards. One technology, an
extractive light-scattering technology, did not meet all the
performance specification levels at all of the alternative
standards.1 Since EPA must show that at least one
commercially available PM CEMS can meet the proposed performance
specification, the fact that 4 of the 5 monitors were able to meet
these performance levels under reasonable worst-case test conditions
adequately shows that the modified specification levels are achievable.
The revised performance specification levels are presented in Table 1,
below.
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\1\ This technology did meet 10 of the 14 specification
comparisons.
Table 1: Revised Performance Specifications for PM CEMS
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Confidence Tolerance
Correlation coefficient interval interval
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0.90 10% 25%
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As previously stated, these performance levels are nearly identical
to the ISO specification for PM CEMS. The only major difference between
these and the ISO specification levels is the correlation coefficient,
which is 0.95 in ISO 10155 and 0.90 in the modified PS11. This is
acceptable since the correlation coefficient does not directly relate
to measurement error while the confidence and tolerance intervals
do.2 The revised PS11 also requires that a minimum of 15
runs be used for the calibration while the ISO specification requires
only 9 runs. The ISO specification is also vague regarding the PM
concentration ranges required for a calibration. The revised PS11
stipulates three ranges: 0 to 30, 30 to 60, and 60 to 100% of the
facility's range of PM emissions.
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\2\ The correlation coefficient is defined as the ratio
Sxy divided by the square root of the quantity
Sxx times Syy. Sxy is a measurement
of error as x relates to y, while Sxx and Syy
are a reflection of the range of the data set. As a result, the
correlation coefficient is not as useful a tool to evaluate
measurement error as the correlation and tolerance intervals. This
is particularly true as the correlation coefficient approaches 1.
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2. Data Availability
EPA had proposed that PM CEMS be used at all times that hazardous
waste is in the unit. See 61 FR at 17441. Commenters to the proposed
rule did not view this favorably. They said this proposal is equivalent
to a 100% data availability requirement for PM CEMS. Commenters stated
that this requirement is not achievable since all mechanical devices
fail at some point, often without warning. They said a data
availability requirement in the 85, 90, or 95% range would be more
acceptable. Commenters suggested that when the PM CEMS were not
available, the PM-related operating parameter limits EPA proposed
should be used in place of the PM CEMS.
EPA largely agrees with this comment. The PM CEMS demonstration
tests show that a 100% data availability requirement is not achievable
for all PM CEMS in all instances. The Agency also agrees that when PM
CEMS are not operating, it is reasonable to provide for some back-up
compliance system in lieu of requiring sources to either stop burning
hazardous waste or have a back-up PM CEMS available. The PM APCD
operating parameters proposed in the event there is no PM CEMS
requirement are a good starting point for identifying such a back-up
system. See the discussion later in this section for more information
on this issue.
Based on these demonstration tests and the comments received, EPA
concludes that a 95% data availability requirement is achievable for
most PM CEMS. Therefore, EPA intends that PM CEMS be used 95% of the
time for compliance. However, there are useful technologies that cannot
meet this 95% data availability requirement. This data availability
requirement should be relaxed in certain instances. For instance, beta-
gages did not meet the 95% data availability requirement during the PM
CEMS tests. EPA believes beta-gages, with their relatively superior
[[Page 67791]]
performance and ability to measure PM emissions at truly wet stacks
(i.e., those with entrained water droplets in the stack gas), will be
useful at some sources for compliance. Therefore, EPA will consider an
85% data availability requirement for beta-gage technology PM
CEMS.3 The Agency anticipates other case-by-case
determinations will be made in the future as more is learned about the
performance, benefits, and data availability limitations of other PM
CEMS technologies.
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\3\ One of the beta gage PM CEMS experienced a 74% data
availability during the PM CEMS demonstration test program. Much of
the additional downtime was because no U.S.-based technicians were
fully trained to service this instrument during this program and
parts and personnel had to be brought to the U.S. Once EPA requires
a new technology, such as PM CEMS, the market for that new
technology is expected to mature in the US similar to how one exists
overseas. As a result, data availability will be better than what
was experienced here.
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Finally, EPA believes that increasing the amount of PM data
available will enable sources to improve their understanding and better
define the relationship between operating parameters and emission
levels. EPA is aware of two relevant examples which are described here.
The first one is an ongoing cooperative effort with industry,
regulatory agencies, and the local public. This effort is focused on a
venturi scrubber-controlled lime kiln at a pulp and paper plant where
testing is being conducted to evaluate the feasibility of a predictive
emission monitoring system (PEMS). Following preliminary measurements
and an experimentally designed test matrix, 595 Method 5 runs were
performed over a wide variety of process and scrubber operating
conditions, and PM emission levels. A correlation coefficient above 0.9
was obtained in correlating PM emission levels with 54 operating
parameters. In comparison, use of PM CEMS represents a powerful tool
for accumulating much data at a cost that is far less than performing
hundreds of Method 5 runs. As a result, PM CEMS allow for a cost-
effective way to implement a PM PEMS model than making hundreds of
Method 5 measurements.
The second example directly relates to the first. The Electric
Power Research Institute (EPRI) has already produced a means to
characterize and correlate PM emissions with operating conditions at
coal-fired utility boilers. PM emissions from utility boilers are
similar to HWCs in that their emissions are affected by a complexity of
variations from a number of fuel and feed characteristics, combustor
operations, and electrostatic precipitator (ESP) operations. As in the
lime kiln case mentioned above, use of PM CEMS represents a more
powerful tool for accumulating and correlating vast amounts of PM
emission data with PM-related operating parameters at a cost that is
far less than performing a large number of Method 5 runs.
These two examples, therefore, lead EPA to believe that a PM CEMS
requirement will allow HWC facilities to better define what PM APCD
operating parameter limits correspond to a given PM emissions
concentration. As a result, the Agency encourages HWC facilities to use
PM CEMS data to better define what operating parameters correspond to
compliance with a facility's PM CEMS limit. The site-specific limit is
discussed further in section IV.B. of this notice.
3. Data Quality Objectives: New Procedure 2 to Appendix F of 40 CFR
Part 60
EPA intends to expand the ISO specification to include certain data
quality objectives. For example, PM CEMS routinely and automatically
check and correct their raw outputs to compensate for phenomena such as
``fogging'' of the optics and drift of the measurement signal. A large
and sudden auto correction is indicative of the need to perform
maintenance on the PM CEMS. To address this concern, EPA intends to
include certain data quality objectives such as: The (PM CEMS internal)
calibration drift not exceed 8% during any drift check; the (PM CEMS
internal) calibration drift not exceed more than 4% per day for five
consecutive days; and the automated (PM CEMS internal) calibration
drift adjustment not exceed 2% for five consecutive days.
These data quality criteria would appear in a new Procedure 2 of
Appendix F to 40 CFR part 60. Just as Procedure 1 of Appendix F deals
with data quality objectives for gaseous CEMS for other CAA rules (CEMS
such as NOX and SOX), Procedure 2 would address
data quality objectives for PM CEMS. Procedure 2 would also include the
following data quality objectives: treatment of ``flagged data;'' PM
CEMS automatic zero and calibration span requirements; conduct of the
Absolute Calibration Audit and the quality of the standards used for
these audits; sample volume audit requirements for extractive systems;
relative calibration audit (RCA) requirements; the treatment of audit
failures; how manual method paired data outliers (see the CEMS NODA 1,
62 FR at 13780) are handled; definition of ``out-of-control''
situations; and how facilities are to respond to these ``out-of-
control'' situations. See Procedure 2 (which appears at the end of this
notice) and the draft final PM CEMS Demonstration Test Report for more
information regarding these requirements and Procedure 2.
B. Manual Method Accuracy
One outgrowth of these PM CEMS demonstration tests is that EPA has
made significant improvements in making Method 5 particulate
measurements. As previously mentioned, the calibration process for PM
CEMS involves correlating PM CEMS outputs to manual method results.
High variability in the manual method results will negatively affect
the PS11 calibration statistics. Therefore, one important way to
improve PS11 statistics is to improve the way manual method
measurements are made. These improvements involve the use of a new
Method 5I (M5i) for low level PM emissions. M5i consists of the
following improvements: improved sample collection; elimination of
possible contamination; and improved sample analysis. Each will be
discussed in the following paragraphs. M5i will be instrumental in
correlating PM CEMS outputs to manual method results. EPA also expects
this new method will be preferred in all cases where low level (i.e.,
below 45 mg/dscm [ cents0.02 gr/dscf]) measurements are
required. In practice, this means that M5i is expected to become the
standard method for most HWCs and many other MACT sources. EPA expects
many of the improvements in M5i can and will be implemented whenever
Method 5 (collectively, including Method 5, 5A, ..., 5H) is used to
make particulate measurements.
M5i is almost identical to the traditional M5. Differences are
discussed below. We also present a comparison of the precision of M5i
(which fully implements these improvements) and the traditional M5
(which largely does not use these improvements) and discuss the need
for and handling of paired M5 data.
1. Modification of the Filter Recovery Process
One way M5i differs from the traditional M5 is through the use of a
light-weight and integrated filter and filter assembly that can be
tared and weighed together. This improves M5 by eliminating the filter
recovery step. The filter recovery step can be a significant source of
measurement error at some sources. In some cases as the filter dries,
the filter adheres itself to the filter assembly. Recovery of the
filter then involves scraping the filter off the filter assembly
leaving some of the filter (and sample) on the filter assembly or
otherwise losing it to the environment. In other cases, the filter
recovery
[[Page 67792]]
process can lead to the loss of sample to the environment as light-
weight particles are lost to the air during handling. It can also lead
to contamination of the sample in cases where fugitive dust from the
environment lands on the filter during the recovery step. Simplifying
the recovery step through the use of a light-weight, integrated filter
and assembly addresses these concerns and thereby improves the
reliability of making PM measurements.
One consequence of this improvement, though, is that the filter
used M5i is smaller than that used in the traditional M5 (47 mm
compared to approximately 90 to 100 mm in the traditional M5). This
smaller filter can plug at higher emissions levels. For this reason,
this aspect of M5i may not be implementable at sources with emissions
above 45 mg/dscm (that is, total train catches exceeding 50 mg).
2. Improved Sample Collection
Another important improvement to M5 is to the sample collection
process itself. These improvements include: ensuring that the nozzle is
90 deg. to the direction of flow at each traverse location; and using
Pesticide Grade (i.e., low residue) acetone for probe rinse. Each is
discussed in the following paragraphs. These improvements to the sample
collection process may also be implemented over time into other
versions of Method 5.
Test crews routinely check the ``level'' of the probe only once
during sampling--prior to or at the beginning of the sampling process
itself. As the traverse progresses, the probe can become ``unlevel,''
i.e., it is no longer at a right (90 deg.) angle to the direction flow
in the stack gas. As the angle of the probe departs from 90 deg.,
inconsistent amounts of sample are collected and thereby causes error
in M5 measurements. This can be corrected by applying a level to the
sample probe and checking the level continuously throughout the
traverse. Ensuring that the probe angle is constant and level
throughout the traverse eliminates this potential source of measurement
error.
Finally, residue contained in the acetone used for the probe rinse
is another source of sampling error. Acetone is used for the probe
rinse since it is a solvent that evaporates readily at room
temperatures and thereby allows rapid weighing of the specimen
following sampling. The standard M5 procedures require that acetone
residue blank levels be determined and that reagent-grade acetone in
glass bottles with no more than 0.001% residue be used for probe
rinses. Acetone comes in many grades, including reagent grade,
depending on how the purchaser intends to use the acetone. Some grades
of acetone contain higher levels of residue. This residue remains after
the acetone evaporates and contaminates the probe rinse, making the
``catch'' during the probe rinse greater than what it really is.
Acetone blanks above 0.001% are not allowed by M5, so the acetone
itself must have a concentration of residue no more than this
requirement for the blanks. M5 also requires that the acetone be stored
in glass containers because acetone from metal containers generally
have a high residue blank level. Test crews routinely use reagent-grade
acetone purchased in small, glass containers since large quantity
purchases create a fire safety and storage issue. Though ordered with
the intent of meeting specifications, acetone suppliers often store
bulk, reagent grade acetone in metal containers and transfer this
acetone to glass containers only to ship the small quantities sold.
This means that the residue concentrations found in reagent grade
acetone are often higher than what is allowed by M5. The unallowable
amount of residue from high blank levels would have a negative effect
on the accuracy and precision of M5 results. This can be avoided by
requiring low-residue, Pesticide grade acetone.
3. Elimination of Contamination
In a general sense, eliminating contamination in the filter
handling processes will eliminate potential sources of error.
Contamination can be avoided by: using a portable desiccator for use in
transporting and holding the filters to and on the stack; using glass
plugs on the filter assemblies to keep them ``pure'' prior to and after
sampling; covering the desiccant with a 0.1 micron screen to eliminate
potential external contamination of filter housing during transport;
and handling the filter assemblies with powder free latex gloves. As
previously discussed, contamination in the M5 process will make
measured PM levels appear to be higher than what they truly are. Each
of these steps to eliminate contamination of the sample will ensure
that fugitive particulate from the environment does not contaminate,
thereby inadvertently causing a positive bias to the measured PM
levels.
4. Improved Sample Analysis
Finally, improved sample analysis will help eliminate error in the
Method 5 measurement process. Specific steps to improve M5 sample
analysis include: Elimination of all sources of static charge (such as
those on the operator, beakers, liners, and balance); use of light
weight Teflon beaker liners for gravimetric analysis of the probe
rinse; maintaining the laboratory area at a humidity level of 30% or
less; and putting a covered desiccant container in the balance weighing
chamber. Each is discussed in the following paragraphs.
High, varying levels of static charge typically produce variations
in repeated weighing of susceptible materials such as glass filter
holder assemblies and Teflon beakers (probe rinse catches). The need
for maintaining a relatively dry atmosphere in the analytical room
further exaggerates the negative effect of static charge on the
weighing process. To control and minimize the consequences of static
charge, EPA found it was necessary to preclude any and all aspects of
static electricity. This entailed using: (1) A static-free mat on the
floor area under the desiccator and balance; (2) a small charge-
neutralizer in the desiccator; (3) another small charge-neutralizer in
the weighing chamber of the balance; and (4) a static dissipator
aerosol spray to prevent static buildup on the Teflon beakers. EPA
found it was not possible to consistently reproduce the same weight
results (that is, within 0.5 mg) until all four measures were done.
The particulate, filter assembly, and filter are often hydrophilic
in nature, i.e., they tend to adsorb water from the air. The amount of
water these materials adsorb depends on the amount of water in the air.
The moisture content of air is often quantified in terms of the
relative atmospheric humidity, or what percentage the actual water
concentration of the air is relative to the saturation concentration.
The higher the relative humidity of the air, the more water is
adsorbed. The converse is also true. As a result, if the relative
humidity in the analysis room is high, the amount of water adsorbed
onto the particulate, filter, and assembly becomes variable and it
becomes increasingly difficult to obtain a stable measurement. Ensuring
that the relative humidity in the analysis room remains at a constant,
low level will ensure that the amount of water adsorbed by these
materials remains relatively small and constant. EPA found that
maintaining the relative humidity of the room to below 30% will control
this source of error.4
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\4\ As humidity levels decrease, static charge tends to
increase. The elimination of static charge, previously discussed,
will aid at eliminating this problem.
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To further control and minimize the adverse affects of humidity on
reproducing results in the weighing
[[Page 67793]]
process, a small covered desiccant container was placed in the
balance's weighing chamber. This ensures that the humidity level in the
weighing chamber is consistent with the humidity level in the
desiccator. The desiccant in the weighing chamber dries fugitive air
entering the chamber from the room, preventing the adsorption of room
air humidity on the materials being weighed.
5. Comparison of M5 and M5i Method Precision
M5i has been validated against Method 5.5 It is also
important to quantify the improvements to M5 just discussed. This can
be done by comparing the precision of both methods at each of the three
proposed PM standards: 34, 50, and 69 mg/dscm for hazardous waste
burning incinerators, LWAKs, and cement kilns, respectively. Precision
at the standards is important since measurements at the standard deal
with compliance determinations at facilities. The best estimate of the
standard deviation is presented to represent this precision.
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\5\ Only the filter, extraction, and weighing steps were tested.
---------------------------------------------------------------------------
For M5i, the results presented are the best estimate of the
standard deviation at each of the three proposed emissions standards.
These results are calculated directly from the data obtained during the
PM CEMS demonstration tests. The relative standard deviation (e.g., the
best estimate of the standard deviation at an emissions concentration,
divided by that emissions concentration) for M5i is in all cases less
than 5%.
Historical data from Method 5 was derived from PM concentrations
ranging from 80 to 255 mg/dscm. This data indicates that the relative
standard deviation for M5 is constant at 10%. Therefore, if one were to
multiple the emissions standard by 10%, one can derive the best
estimate of the standard deviation at the three proposed emissions
standards.
Table 2, below, illustrates this comparison and shows that M5i is
an improvement to M5.
Table 2: Comparison of Method 5 and Method 5i Standard Deviations
------------------------------------------------------------------------
Best estimate of the
standard deviation (mg/
Proposed PM emissions standard (mg/dscm) at 7% dscm)
oxygen -------------------------
Method 5 Method 5i
------------------------------------------------------------------------
34 3.4 1.67
50 5.0 2.24
69 6.9 2.85
------------------------------------------------------------------------
6. Paired Data
Throughout most of the PM CEMS demonstration tests, EPA used two
simultaneous Method 5i sampling trains. These two simultaneous trains
are called ``paired trains'' and the paired train data are called
``paired data.'' The average of the paired data from the two trains was
considered the method result. If the ``paired data'' differed by more
than 30% from the method result, EPA eliminated the method result from
the calculation of the calibration.
EPA's experience is that, despite the efforts just discussed to
control method variability, intangibles which are unknown or
unquantifiable can cause variability in M5 (and M5i) measurements.
Since it is important that highly accurate M5 measurements be obtained
for calibrating PM CEMS, these intangibles must be identified in some
way and data affected by these intangibles must be eliminated from the
PM CEMS calibration. The fact that two simultaneously run M5 (or M5i)
measurements do not agree is ample evidence that something in the
sample collection and analysis process was not consistent.
Comments received during the comment period for CEMS NODA 1 stated
that this process would not be allowed if a facility were doing a
calibration for compliance. To address this concern, EPA has
incorporated this outlier procedure in the new Procedure 2 and M5i.
Having this procedure in the regulations will allow facilities to
exclude this type of erroneous data from their PM CEMS calibrations.
Please note that this procedure applies only if paired data are
obtained. Single measurements obtained at different times are not
paired data. Single runs cannot be eliminated by comparing these
results to other single measurements.
EPA strongly encourages facilities to use paired data during their
calibrations. Beyond the ability to eliminate paired data outliers from
the PM CEMS calibration, using the average of two runs as the method
result has a moderating affect on the calibration statistics EPA
calculated and used to base the PS11 revised in today's notice. This
moderating effect improves the PS11 criteria relative to what they
would be if paired data were not used. Some facilities may find it
difficult to obtain a suitable calibration using only single M5
measurements. However, while we encourage using paired data, we are not
requiring paired data for PM CEMS calibrations. This choice can be left
to the facilities to determine what makes the most economic and
technical sense at their site.
C. Transferability of These Demonstration Test Results to Other HWC
Sources
EPA believes this demonstration test program adequately shows that
PM CEMS will meet PS11 at most hazardous waste incinerators, cement
kilns, and light-weight aggregate kilns. These tests were conducted at
a reasonable worst-case facility for performance relative to the
proposed performance specifications6. Therefore, a PM CEMS
should pass the performance measures described in the revised draft
PS11 at most HWC sources. The paragraphs below discuss specific aspects
of PM CEMS and their applicability to each HWC source category.
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\6\ For more on EPA's rationale that this is a reasonable worst-
case test, see CEMS NODA 1 and the PM CEMS Demonstration Test report
sited here.
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For cement kilns, in-situ light scattering PM CEMS are
operationally very similar to continuous opacity monitors (COMs), a
technology employed at these sources for many years. Light-scattering
PM CEMS differ from COMs only in the way they obtain and interpret the
light from the source. As shown in the LaFarge tests,7
though, an informed decision is required to determine what type of in-
situ light-scattering PM CEMS is best suited for these sources. One PM
CEMS used at LaFarge was built with a heated air purge system to blow
cement kiln dust away from and out of the optics of the monitor while
the other was not. The monitor with the heated air purge performed very
well over the course of the tests, though improvements to the Method 5
measurements and a routine cleaning of the optics could have improved
performance. The PM CEMS without the heated air purge suffered
operational difficulty. In addition, PM from cement kilns is mostly
process dust (i.e., raw material). As such, its physical properties are
not significantly affected by changes in waste or fuel feeds.
Accordingly, in-situ light-scattering PM CEMS will pass performance
specifications at cement kilns if an informed decision is made to
[[Page 67794]]
purchase a monitor that is designed to address the dusty environment at
these facilities.
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\7\ See section 2.6.7 of the PM CEMS Demonstration Test Report.
---------------------------------------------------------------------------
EPA believes that LWAKs are very similar to cement kilns relative
to the applicability of PM CEMS, and therefore the conclusions drawn in
the preceding paragraph also apply to LWAKs.
For incinerators, there are certain unique situations which must be
discussed: incinerators with truly wet stacks; incinerators with waste
heat boilers; and mobile incinerators.
As was the case with cement kilns, HWC incinerators with truly wet
stacks (i.e., those with entrained water droplets in the stack gas)
need to make an informed choice regarding what PM CEMS technology they
elect to use. In-situ light-scattering PM CEMS are likely to have
operational difficulty since the water droplets entrained in the stack
gas will be mistaken for particulate. This is a readily accepted source
of error and means that in-situ light-scattering PM CEMS are not a
practical choice for these sources. Beta-gage and certain other light-
scattering PM CEMS, however, are designed with extractive reheat
systems which heat up the extracted gas to above the water condensation
temperature. Incinerator groups are currently working to test these
types of systems to gain first-hand experience and data regarding the
use of PM CEMS at facilities with truly wet stacks. EPA encourages
these tests since they will result in valuable data which can be
communicated to personnel at incinerators with truly wet stacks to
assist their PM CEMS purchasing decisions.
Incinerators equipped with waste heat boilers (WHBs) downstream of
the combustion chamber(s) also require special consideration. Like
boilers, these incinerators blow soot periodically to clean the boiler
tubes. PM emissions will increase and the physical properties
(pertinent to PS11) of the PM may change during periods of soot
blowing. To help address the impact of soot-blowing, sources would be
required to include soot-blowing episodes during a minimum of three
calibration runs. This will ensure that calibration captures the higher
emissions that can occur during soot-blowing, thus minimizing the need
to extrapolate the calibration curve beyond measured values. In
addition, including soot-blowing during calibration runs will enable
the source to determine whether any change in the physical properties
of the PM during soot-blowing has adversely affected the calibration
(i.e., as evidenced by an inability to meet PS 11 when the soot-blowing
runs are included).
EPA requests comment on this approach to address the special
problems that soot-blowing may cause. In particular, EPA seeks the
following information:
--How many incinerators are currently equipped with WHBs? Are sources
likely to remove WHBs to facilitate compliance with the MACT standards
(e.g., D/F)?
--The normal frequency and duration of soot-blowing. Under what
conditions does the frequency and duration of soot-blowing change? How
often does this change(s) occur?
--How do PM emissions for runs that include episodes of soot blowing
compare to runs without soot blowing?
--How does the effect of the APCS, waste and fuel types, and other
relevant factors impact changes to the PM concentrations and physical
properties when one compares PM during soot-blowing and PM at other
times.
The reader should note that EPA intends to promulgate MACT
standards for hazardous waste boilers as part of Phase II of the HWC
rulemaking. EPA intends to address the applicability of PM CEMS to
boilers then. If because of unforeseen reasons EPA provides a PM CEMS
waiver for incinerators with WHBs, EPA would readdress the
applicability of PM CEMS to hazardous waste incinerators with waste
heat boilers in Phase II.
Finally, another class of hazardous waste incinerators are used at
Superfund sites during the clean-up process. These mobile incinerators
have small, limited waste processing capacity and are often trucked to
the site as needed. EPA is concerned that the variability of the feed
to mobile incinerators is beyond what was experienced at the DuPont
facility. As such, a unique calibration might be required for every
clean-up site, which is unnecessarily burdensome. Given the PM CEMS
implementation schedule discussed in section IV.A., below, implementing
PM CEMS at these incinerators may not be feasible, and EPA is
considering whether to waive the PM CEMS requirement for Superfund
mobile incinerators.
If the PM CEMS requirement is waived for certain facilities, the
other, traditional operating parameters discussed in this NODA would be
used instead to document compliance.
IV. PM CEMS: Implementation and Compliance 8
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\8\ The reader should note that HWCs are currently regulated
under RCRA. Sources with a different regulatory history are likely
to have a different compliance regime than the one described here.
One should not assume that the compliance and implementation scheme
described here will necessarily be applied to sources with a
different regulatory history.
---------------------------------------------------------------------------
A. PM CEMS Compliance Schedule
Many comments received in response to the proposed rule stated that
facility personnel are not familiar with the operation and maintenance
characteristics of PM CEMS, or how to control their operating
conditions to ensure compliance using PM CEMS. For this and reasons
explained in section IV.B., EPA plans to allow a 12-month phase-in
period before PM CEMS would be used as a compliance parameter. This
section describes this compliance schedule.
Prior to the date PM CEMS would be used for compliance (i.e.,
during the 12-month phase-in period), limits on key PM-related and
other key operating parameters (e.g., metals feedrate) would be used to
ensure compliance with the MACT standards for PM, SVM, and LVM. This
one year phase-in period has four key milestones: The Compliance Date;
the performance Test Date; the Certification of Compliance (CoC) date;
and the Certification of PM CEMS performance date. By the Compliance
Date,9 facilities would determine, using engineering
judgment, the operating parameter limits necessary to ensure compliance
with the standards. These initial operating parameter limits would be
specified in a Precertification of Compliance (Pre-CoC) that would be
submitted to the permitting authority by the Compliance Date. By the
Test Date, which is nominally no later than six months after the
Compliance Date, facilities would have to conduct a performance test to
document compliance with the MACT emissions standards and identify
operating parameter limits based on levels achieved during the test.
Results of the performance tests and these revised operating parameter
limits would be submitted to the permitting authority in a
Certification of Compliance (CoC) nominally no more than nine months
after the Compliance Date. The operating parameter limits in the CoC
would be used as surrogate compliance measures to ensure that the
efficiency of
[[Page 67795]]
the PM control device was maintained at performance test levels until
the one-year anniversary date of the Compliance Date. Beginning at that
time, facilities would start using the PM CEMS and cease using the
operating parameters as their primary operating parameter for PM
control.
---------------------------------------------------------------------------
\9\ The Clean Air Act states that the Compliance Date can be no
more than three years after the effective date of the rule (i.e.,
date of publication in the Federal Register), unless a source
obtains an (up to) one-year time extension of the Compliance Date.
---------------------------------------------------------------------------
During this phase-in year, there are important PM CEMS-related
activities being performed. For instance, the PM CEMS, like all other
equipment necessary for compliance with the MACT standards, must be
installed by the Compliance Date. Like all other tests for the rule,
the PM CEMS calibrations and initial certifications (see section 8.3 of
PS11 and section 4 of Procedure 2) must also be performed by the Test
Date.
As discussed in the PM CEMS Demonstration Test Report, the
mathematical characteristics of a light-scattering PM CEMS calibration
curve can be difficult to determine. For this reason, a second
calibration would be required within 9 months of the Compliance Date if
a light-scattering PM CEMS is used. After this second calibration is
performed the source would compare the two calibrations separately to
determine which mathematical model best represents the data. This
information (i.e., the analysis of which mathematical model is best
suited for the calibration at this source and the calibration comprised
of all valid calibration data obtained) would be included in a
Certification of PM CEMS Performance (CoP) submitted within 12 months
after the Compliance Date. (A CoP for beta-gage CEMS would also be
submitted at this time, but would certify performance based on a single
calibration.)
This CoP would also include (for all types of CEMS) the analysis of
CEMS data to identify an achievable CEMS-based PM operating parameter
limit. See section IV.B., below, for more information regarding the PM
CEMS operating parameter limit. On the one-year anniversary of the
Compliance Date, facilities would also cease using the PM control
device operating parameter limits (such as pressure drop across a
fabric filter or total power input to an ESP) and start using the PM
CEMS operating parameter limit as their primary compliance parameter
for the PM control device.
A source using a light-scattering PM CEMS would be required to
perform a third calibration of the PM CEMS within 12 months of the
Compliance Date. The third calibration would verify that the
mathematical model selected by comparing the first two calibrations is
correct. If not, to the approach must be modified based on the new
data. If the model needed to be revised, the source would be required
to recalculate the PM CEMS operating parameter limit considering the 12
months of data following the Compliance Date. If the model did not need
to be revised, the source could elect to recalculate the PM CEMS
operating parameter limit considering the full 12 months of CEMS
recordings. (We request comment on whether all sources required to
perform a third calibration should be required to recalculate the PM
CEMS operating limit even if the calibration curve model did not need
to be revised.) The results of the third calibration,10
reassessment of the calibration model, and recalculation of the PM CEMS
operating parameter limit would be submitted in a second CoP. This
second CoP would be provided to the permitting authority within 15
months of the Compliance Date. Note that this second CoP would not be
required if a source uses a beta-gage type PM CEMS that needs only one
calibration. A source using a PM CEMS that requires only one
calibration (i.e., a beta-gage) would have the option, however, of
submitting a second CoP if it wants to update the PM CEMS operating
parameter limit based on a full year of data.
---------------------------------------------------------------------------
\10\ This would involve the verification that the mathematical
model used for the calibration is correct, a recalculation of the
``master'' calibration comprised of all three calibration curves,
and a revised site-specific PM CEMS operating parameter limit (this
time, using the first 12 months of data).
---------------------------------------------------------------------------
Table 3 summarizes how PM CEMS would be implemented for compliance.
Following this implementation schedule, facilities would be required to
document compliance with the MACT PM standard during periodic
performance testing. As discussed in section IV.F. below, a source
would have the option of using the PM CEMS or the manual method for
this determination. In addition, sources would be required to
recalculate their PM CEMS operating parameter limit based on the
previous year of CEMS data recorded when the source operated within the
operating parameter limits established during the new performance test.
This recalculation of the PM CEMS operating parameter limit is
necessary since the new performance test is likely to result in
numerically different PM-related APCD operating parameters than
resulted from the previous test.11 Facilities would submit
the revised operating parameter limits, including the revised PM CEMS
operating parameter limit, in a CoC describing the results of the new
performance test.
---------------------------------------------------------------------------
\11\ If the PM concentration and operating parameter limits
resulting from the subsequent performance test are more stringent
than those from the previous test, the facility would have the
option of not recalculating their PM CEMS operating parameter limit
and continue to operate under the older, more stringent limit.
[[Page 67796]]
Table 3: PM CEMS Compliance Schedule
----------------------------------------------------------------------------------------------------------------
By this date These PM CEMS activities would be performed
----------------------------------------------------------------------------------------------------------------
Compliance date............................. PM CEMS installed
Precertification of Compliance (Pre-CoC) submitted that
establishes PM APCD (and other) operating parameter limits to
ensure compliance with the SVM and LVM (and possibly D/F)
standards based on engineering judgment.
CD + 6 months (the ``Test Date'')........... PM CEMS calibration tests performed during MACT performance test.
Method 5i used to demonstrate compliance with the manual method-
based PM standard.
CD + 9 months............................... Certification of Compliance (CoC) submitted that establishes PM
APCD (and other) operating parameter limits to ensure compliance
with the SVM and LVM (and possibly D/F) standards based on what
levels were determined to correspond to compliance with the
standard during the Performance Test. (These limits supersede
those identified in the Pre-CoC.)
A second calibration of light-scattering PM CEMS is performed.
CD + 12 months.............................. Source identifies calibration curve, calculates the PM CEMS
operating parameter limit (through 9 months), recommends
alternative PM control device operating parameters and their
numerical limits, and submits a Certification of PM CEMS
Performance (CoP).
Source ceases using PM control device operating parameters as the
primary mode of compliance for PM and starts using the PM CEMS.
The operating parameters defined in the CoC are used for
compliance only when the PM CEMS is unavailable.
Source reports initial calibration (composite of all calibrations
through 9 months), PM CEMS-based limit, and revised operating
parameter limits (for use during CEMS malfunctions) to permitting
authority.
A third calibration of light-scattering PM CEMS is performed.
CD + 15 months.............................. Sources using light-scattering PM CEMS revise the calibration
curve if necessary based on the third calibration, recalculate
the PM CEMS operating parameter limit (through 12-months), update
the PM control device operating parameter limits for use during
CEMS malfunctions, and submit a second CoP documenting this
information.
The source starts using the revised operating parameters reported
in the CoP during periods when the PM CEMS is unavailable unless
those alternatives have been disapproved by the permitting
authority.
----------------------------------------------------------------------------------------------------------------
B. PM CEMS Operating Parameter Limit
EPA proposed using site-specific limits on key operating parameters
of the PM control device (e.g., pressure drop across a fabric filter)
to ensure that the device maintained its collection efficiency at
performance test levels. These limits, in combination with other
operating parameter limits (e.g., metals feedrate controls) would
ensure compliance with the semivolatile metal (SVM) and low volatile
metal (LVM) MACT standards. See 61 FR 17376 and 17430 (April 19, 1996).
These operating parameter limits on the PM control device would also
ensure compliance with the MACT PM standard 12, and possibly
the MACT dioxin and furan (D/F) and mercury (Hg) standards if the
source uses activated carbon injection to control these HAPs.
13 The availability of PM CEMS allows the Agency to improve
upon this approach through the use of PM CEMS as the sole PM control
device operating parameter 14. PM CEMS are a more sensitive
and accurate operating parameter than the conventional PM-related
operating parameters now used.
---------------------------------------------------------------------------
\12\ The Agency has proposed a MACT PM standard as a surrogate
to control emissions of non-enumerated metals HAPs (i.e., metal HAPs
other than those for which specific standards have been proposed--
Hg, SVM, and LVM). Those non-enumerated HAPs are Sb, Co, Mn, Ni, and
Se.
\13\ The Agency proposed that the site-specific PM limit be a
compliance parameter for the D/F standard irrespective of whether
activated carbon injection was used as a control device. This
requirement was grounded upon EPA's initial view that a significant
amount of D/F (and other heavy organic compounds) are adsorbed onto
particulate. As a result, PM needed to be controlled to ensure
continuous compliance with the D/F standard. The Agency is now
considering comments that significant D/F may not be adsorbed onto
PM. Cement and lightweight kiln PM, in particular, is generally
process dust (i.e., processed raw material). This process dust has
little affinity for adsorbing D/F. However, EPA's ultimate decision
on whether to limit PM on a site-specific basic does not depend on
whether there is a need to control PM at all HWCs for D/F control. A
site-specific PM limit is still needed to ensure compliance with the
SVM and LVM standards at all HWCs. Sources that use activated carbon
injection, howver, would be expected to have a significant amount of
D/F on the PM.
\14\ Note that the MACT standard for PM would continue to be a
manual methods-based standard. See subsection IV.F., below, for
options facilities could have to use PM CEMS for direct compliance
with this PM standard.
---------------------------------------------------------------------------
This section describes how PM CEMS would be implemented as an
operating parameter for the SVM, LVM, PM, and possibly D/F and Hg
standards. The reader should note that the proposed MACT standard for
PM is and will continue to be a manual methods-based standard. The
reader is referred to section IV.F., below, for options a facility
could choose to use PM CEMS as a direct indicator of compliance with
the MACT PM standard.
1. Introduction
The PM CEMS operating parameter limit would be determined using the
PM CEMS data obtained during normal operations from the Compliance Date
to the time when the calculation of the operating parameter limit is
performed. Although the PM CEMS would be used as an operating parameter
limit here, an approach to establishing this limit could be very
similar to how EPA establishes national standards from CEMS data. The
municipal waste combustor rule published on February 11, 1991, has an
example of how this is done 15.
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\15\The methods used for establishing CEMS standards in the
February 1991 MWC rule are described in Appendices A and B of EPA
document number EPA-450/3-91-004, dated December 1990. This document
can also be found in the Air Docket, located in the Mall area of EPA
Headquarters, 401 M Street, SW, Washington, DC 20460. It is part of
docket number A-89-08-V-B-3.
---------------------------------------------------------------------------
EPA notes that even though the PM CEMS operating parameter limit
and the manual methods-based PM standard are both in units of
particulate concentration, it is likely that the PM CEMS operating
parameter limits will have a different numerical value than the manual
methods-based MACT PM standards. This is because the MACT PM standards
would be based on manual methods testing with no fixed averaging
period. PM CEMS operating parameter limits would have both a fixed
averaging period and a calculated
[[Page 67797]]
numerical limit. As discussed in section 4, below, the numerical value
of a limit or standard is a function of the averaging period. Since it
is likely that the PM MACT standard and the PM CEMS operating parameter
would have different averaging periods, one would expect the numerical
value of the PM CEMS operating parameter limit that indicates
compliance with the MACT standards would differ from the numerical
value of the MACT PM standard.
2. Data Excluded From Calculating the PM CEMS Operating Parameter Limit
Before calculating the PM CEMS operating parameter limit, the PM
CEMS data set must be screened to remove PM CEMS data recorded when the
PM CEMS was not available or the source was out of compliance with the
operating parameter limits established during the CoC.
First, the facility must remove from the data set all PM CEMS data
accumulated while the PM CEMS was not available or not performing
acceptably as defined by the regulations. Examples of the data not
included in the calculation of the PM CEMS operating parameter limit
include data obtained when the PM CEMS was ``out-of-control'' as
defined in Procedure 2 and PS11, periods when the PM CEMS was not
analyzing stack gas (as would happen during calibrations, maintenance,
etc.), and periods when the facility was not in operation.
Next, the facility would further screen the data to exclude times
when the facility was not operated in accordance with the operating
parameter limits resulting from the performance test and reported in
the CoC 16. Note that the CoC operating parameter limits
would supersede the Pre-CoC operating parameter limits for this
screening purpose. Although the Pre-CoC operating parameter limits may
be less stringent than the CoC limits and were valid limits prior to
submitting the CoC, the CoC limits are based on performance testing and
as such show what operating parameter levels reflect compliance with
the standards. The facility must also remove any data collected during
periods of PM APCS upset irrespective of whether the operating
parameter limits were exceeded. 17
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\16\ For simplicity, EPA proposes to exclude data from all
periods in which the facility operated outside of the operating
envelope defined in the CoC irrespective of whether the parameter in
question affects PM control. Defining what operating parameters are
or are not related to PM control would force another layer of
complexity in this step.
\17\ Episodes of high PM emissions caused by periodic, routine
maintenance cycles (e.g., ESP rapping; soot-blowing for waste heat
boiler equipped incinerators, etc.) would not be considered upset
conditions. We request information on how to objectively distinguish
between high PM emissions attributable to PM control device upset
conditions versus normal emissions variability.
---------------------------------------------------------------------------
3. Determining the Normality of the Data
To calculate the PM CEMS operating parameter limit, the CEMS
recordings 18 must be averaged over an appropriate averaging
period. (See the discussion in the following section.) Accordingly,
sources would be required to identify the mathematical model that best
fits the screened CEMS data for purposes of averaging the data. For
example, a log-or exponential fit may better represent a ``normal'' fit
relative to an arithmetic model. To identify which mathematical model
represents the best fit, facilities would calculate the Shapiro-Wilk
Normality test statistic (W) at the 95% confidence level using the data
obtained from the PM CEMS 19. The mathematical model with a
Shapiro-Wilk test statistic closest to one (1) would be the model used
for averaging at the facility. This mathematical model would be used
for all PM CEMS emissions averaging at the facility.
---------------------------------------------------------------------------
\18\ The light-scattering CEMS provide instantaneous data,
recorded every minute as one-minute block averages. Beta-gage CEMS
have sampling periods longer than 1 minute.
\19\ Note that batch CEMS, such as beta-gages, may have sampling
periods longer than 1 minute. In this case, the test statistic would
be performed using the batch results.
---------------------------------------------------------------------------
4. Averaging Periods for the PM CEMS Operating Parameter Limit
Fundamental to any emissions control parameter is the way averaging
affects an emissions standard or limit. At a fixed numerical value, a
standard or limit is more stringent as the averaging period decreases
and less stringent as the averaging period increases because of
emissions variability. In the proposed rule, EPA said that an
appropriate averaging period for PM CEMS would be the length of time it
takes to make three Method 5 runs. The Agency still believes this is an
appropriate point of departure for the averaging period for the PM CEMS
operating parameter limit.
We proposed a 2 hour averaging period for PM CEMS, reasoning that
it would take 40 minutes to accumulate enough PM sample to meet Method
5 requirements for sample ``catch.'' See 61 FR at 17379. Commenters
argued, however, that although it takes 40 minutes to accumulate enough
sample, test crews routinely sample for one hour. In addition, comments
received in response to CEMS NODA 1 said the sampling time for a Method
5 run can vary from 1 to 8 hours. Basing the averaging period for the
PM CEMS operating parameter limit on the length of time it takes to
perform three Method 5 runs would result in an averaging period in the
range of 3 to 24 hours 20. This is still being evaluated.
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\20\ Three to 24 hours is within the range of CEMS averaging
periods EPA typically promulgates. From a broader perspective,
averaging periods vary from regulation to regulation depending on
the analysis of issues pertaining to the technical, policy, and
regulatory history of each particular situation. Therefore, other
source categories may or may not have the same averaging period as
the one established for PM CEMS at HWC, depending on the outcome of
this analysis of issues.
---------------------------------------------------------------------------
5. Options for Calculating the PM CEMS Operating Parameter Limit
As discussed above, the stringency of the standard is a function of
two variables--its numerical limit and the averaging period. Equally
stringent standards would have a higher numerical limit at shorter
averaging period and a lower numerical limit at a longer averaging
period. Thus, to calculate the PM CEMS operating parameter limit, one
of these two variables must be held constant--either the numerical
limit or the averaging period. This section discusses two options for
calculating an achievable PM CEMS operating parameter limit by defining
the averaging period. EPA investigated ways to define the numerical
limit and allow facilities to calculate the averaging period associated
with that numerical limit, but found these alternatives often resulted
in trial-and-error type calculations and might result in all facilities
having different limits and averaging periods. We believe these
alternatives are too labor intensive and confusing--both for facilities
and the enforcement authority--and rejected this approach. Based on
comments and further analysis, the Agency will prescribe one
methodology in the final rule.
a. Using Rank Statistics to Calculate the PM CEMS-based Operating
Parameter Limit at One, Fixed Averaging Period. Under this approach,
the Agency would establish an averaging period common to all sources
and each source would calculate its PM CEMS operating parameter limit
using rank statistics. (As discussed above, EPA is considering
selecting an averaging period from within the range of three to 24
hours.) The averaging period would be the same for all facilities but
the numerical value of the PM CEMS operating parameter limit would
differ from facility-to-facility based on the historical data obtained
at each facility.
[[Page 67798]]
Using the rank statistics option to calculate the limit would
involve the following steps. First, the facility would take the
screened PM CEMS data (i.e., after non-compliance data has been
removed) and calculate rolling averages sequentially from the
Compliance Date 21 using the best-fit mathematical model and
the averaging period EPA promulgates. The facility would then take the
resulting rolling averages and sort them in order from lowest to
highest. The facility's PM CEMS operating parameter limit would be the
95th percentile highest PM CEMS rolling average, by rank, experienced
during the period the PM CEMS data was accumulated. The 95th percentile
is proposed here because it is the percentile level EPA historically
uses for these types of calculations. EPA could promulgate some other
percentile level, the 90th or 99th for example, if another percentile
level is achievable and better represents good PM control.
---------------------------------------------------------------------------
\21\ For simplicity, we believe it is best for facilities to
ignore periods when the CEMS recorded data which was screened out
and calculate the rolling averages as if the remaining data occurred
sequentially. EPA specifically requests comment on this approach.
---------------------------------------------------------------------------
This rank statistics option is easier to implement, relative to the
other options. It also would result in a PM CEMS operating parameter
limit that is in the range of actual emissions experienced by the
facility (i.e., as opposed to statistically projected emissions) and
demonstrated by the facility to be achievable over time. Since the
limit for all sources would be based on an averaging period that would
be fixed in the rulemaking, the limit would be easier to enforce as
well.
b. The Traditional Standard Setting Approach. Another approach the
Agency is considering to determine the PM CEMS operating parameter
limit is to use the way EPA has established CEMS-based standards in the
past. This approach involves calculating the average and standard
deviation of the data set and projecting an emissions level associated
with the data. As discussed in the MWC rule, EPA calculated
``continuous compliance levels'' for each source using the equation,
below.
where: y=x+K*5
y = the continuous compliance level;
``x-bar'' = the sample average
k = a constant associated with the averaging period and one
exceedance per year; and
s = the sample standard deviation.
This option has some benefits and weaknesses. As discussed, it
reflects a procedure EPA has previously used to establish CEMS-based
standards. It would also result in every facility having the same
averaging period and thus making it easier to track and enforce.
However, more complicated statistics are involved. EPA also compares
emissions from more than one facility when it uses this approach to set
standards and would be unable to oversee the application of this
approach on a site-specific basis. As a result, this approach may be
unworkable as a way to establish a PM CEMS operating parameter limit.
6. Consideration of a Variance Procedure to Project a Higher PM CEMS
Operating Parameter Limit
As discussed previously in today's notice, the PM CEMS operating
parameter limit would be based on CEMS recordings during the nine
months after the Compliance Date during those periods of time that the
source was operating within the operating parameter limits established
during the performance test (i.e., the operating parameter limits
established in the Certification of Compliance (CoC)). Comments
received in response to the proposed rule questioned the need to
establish PM-related operating parameters based on the performance test
if: (1) PM emissions measured using manual methods during the
performance test were well below the PM MACT standard; and (2)
emissions of HAPs (i.e., SVM, LVM, and possibly Hg, and D/F) for which
PM would be used as an operating parameter limit were well below their
MACT standards. Commenters were concerned that, although their sources
may readily achieve the MACT PM standard, it may be difficult
22 or expensive to ensure that performance test PM levels
are representative of the full range of levels achieved during
operations. The same situation could occur with the PM CEMS operating
parameter limit just discussed. Infrequent exceedances of the PM CEMS
operating parameter limit might or might not be an indication that the
SVM, LVM, Hg, D/F, or PM MACT emission standards have been exceeded.
Accordingly, commenters recommended that the rule allow sources to
project higher PM-related operating parameters based on how much
performance test emissions for these HAPs were below their MACT
standards.
---------------------------------------------------------------------------
\22\ For example, some PM control devices are so over-designed
that it is difficult to force them to operate at elevated PM levels
for the duration of a performance test.
---------------------------------------------------------------------------
EPA agrees in theory that establishing the PM CEMS operating
parameter limit considering performance test operations (i.e.,
historical CEMS data when the source operated within the CoC operating
parameter limits) could result in an overly conservative operating
parameter for PM control at sources with low PM and low HAPs that
require PM control to ensure compliance. To address the concerns
expressed in the comments received on the proposed rule, the Agency is
considering a variance procedure to establish an higher projected PM
CEMS operating parameter limit.
The variance procedure would allow facilities with very low
concentrations of PM and HAPs requiring PM control for compliance to
increase their PM CEMS operating parameter limit (derived from
operations within the CoC operating parameter limits). The factor used
to increase the PM CEMS operating parameter limit could be defined as
the ratio of the MACT standards for which PM control is required to
assure compliance, to the performance test levels of those HAPs. To
ensure that the source is still be in compliance with the MACT PM
standard, the same ratio would be calculated for the PM standard to the
unadjusted PM CEMS operating parameter limit. This approach is based on
the principle that, at a facility which has experienced no changes in
facility operations, the ratio of emissions of HAPs which require PM
control to ensure compliance to the PM concentration in the stack is
either constant or decreases as PM increases. In addition, revised
(i.e., less stringent) traditional operating parameter limits for the
PM control devices corresponding to the higher projected PM CEMS
operating parameter limit could be established based on historical
operating data at levels near the higher projected PM CEMS operating
parameter limit.
For illustration, an example follows. Assume that a hazardous waste
incinerator has low metals in the feed and uses a HEPA filter for PM
control. Further assume that: This incinerator's measured metals
emissions during the performance test were 10 g/dscm and 7
g/dscm for SVM and LVM, respectively; that the PM
concentration measured during the performance test was 5 g/
dscm; for simplicity that PM control is not required to assure
compliance with the D/F and Hg standards; the unadjusted PM CEMS
operating parameter limit is 15 mg/dscm; and from the HWC NODA
published on May 2, 1997, that the promulgated standards are 100
g/dscm, 55 g/dscm, and 34 mg/dscm for SVM, LVM, and
PM, respectively. The ratio of the standard to the measured levels are
10 and 7.8 for SVM and LVM. For PM,
[[Page 67799]]
the ratio is 6.8. The unadjusted PM CEMS operating parameter limit
would be increased by a factor of 6.8 since the ratio calculated for PM
has the lowest numerical value.
a. HAPs for which PM control is necessary to ensure compliance. PM
would be used as an operating parameter limit for semivolatile metals
(SVM), low volatility metals (LVM), and if activated carbon is used,
dioxin and furan (D/F) and mercury (Hg). See 61 FR 17422 and 17430
(April 19, 1996). Although the Agency is reconsidering whether PM is an
appropriate operating parameter to ensure compliance with the D/F
standard in some cases,23 PM would be an appropriate
operating parameter if activated carbon injection were used to control
D/F or mercury. This is because D/F and mercury adsorb onto the
activated carbon, and as PM emissions increase, emissions of activated
carbon with adsorbed D/F and mercury increase.
---------------------------------------------------------------------------
\23\ The Agency is considering comments that significant D/F may
not be adsorbed on emitted PM in all cases. Cement and lightweight
kiln PM, in particular, is generally process dust (i.e., raw
material) that has little affinity for absorbing D/F.
---------------------------------------------------------------------------
b. Projecting a higher PM CEMS operating parameter limit
considering the ratio of the standard to the measured level of a HAP.
The variance would be based on the principle that, as PM emissions
increase, the ratio of emissions of each HAP for which PM is an
operating parameter limit (i.e., SVM, LVM, and possibly D/F and Hg) to
PM emissions either is constant or decreases. Thus, the PM CEMS
operating parameter limit derived from operations within the CoC
operating parameter limits could be increased without exceeding the
MACT standards for those HAPs by a factor considering the ratio of the
standard for each of those HAPs to the performance test level of each
HAP.
LVM are generally not volatilized in the combustion chamber and
thus are evenly distributed over all sizes of particulates. Thus, as PM
emissions increase, the ratio of LVM emissions to PM emissions will be
constant.
SVM are generally volatilized during combustion and condense
preferentially on small particulates prior to (or in) the PM control
device. Thus for many PM control devices, as PM emissions increase, the
ratio of larger particulates to smaller particulates increases, and the
ratio of SVM emissions to total particulate emissions decreases (i.e.,
because the larger particulates have a lower concentration of SVM). For
emission control trains where PM particle size may remain constant with
an increase in PM emissions, the ratio of SVM emissions to PM emissions
would remain constant.
D/F and Hg are adsorbed onto the surface of carbonaceous
particulates (e.g., activated carbon). Smaller particulates have a
larger surface area per mass of particulate than larger particulates,
and thus D/F and Hg concentrations would be higher for smaller
particulates. Thus, similar to SVM, as PM emissions increase and the
ratio of larger particulates to smaller particulates increases, the
ratio of D/F and Hg emissions to total particulate emissions should
decrease (i.e., because the larger particulates have a lower
concentration of D/F and Hg).
The PM CEMS operating parameter limit derived from performance test
operations (i.e., calculated from historical CEMS data when the source
operated within the regulations) could be increased without exceeding
(theoretically) the MACT standards for SVM, LVM, and possibly D/F and
Hg by the ratio of the standard for each of those HAPs to the
performance test level of each HAP. It would be reasonably
conservative, however, to project the higher PM operating parameter
limit by the ratio of some fraction of the standard for those HAPs to
the performance test level of each HAP. This fraction of the standard
would need to allow for adequate flexibility for sources with low PM
and HAPs for which PM control is required while ensuring that the
standards are being met continuously. A specific percentage of the
standard within the range of reasonable values--50% to 100%-- could be
selected and would be appropriate given the uncertainty of projecting a
PM operating limit that is a primary compliance measure for several
MACT emissions standards. EPA believes choosing 75% of the standard as
the basis for calculating the ratio is a reasonable balance of these
issues. The percentage that would be appropriate is a point of interest
for the Agency.
Given that the PM CEMS operating parameter limit is a compliance
measure for SVM, LVM, and possibly D/F and Hg the allowable higher
projected PM CEMS operating parameter limit would be the lowest of the
values projected for each of these standards. For example, if the
projected PM CEMS operating parameter limit based on the ratio of 75%
of the SVM standard to the SVM performance test level was lower than
the PM CEMS operating parameter limit projections for LVM (and possibly
D/F and Hg), then the SVM-projected PM CEMS operating parameter limit
would be used to ensure that the SVM standard was not exceeded at the
higher projected PM operating parameter limit.
The Agency is concerned, however, about increasing the PM CEMS
operating parameter limit itself by the ratios discussed above. This is
because the limit would be established at the upper end of the range of
actual CEMS readings, or perhaps at levels that statistically exceed
what would be expected. See above discussion of options for calculating
the PM CEMS operating parameter limit. It may be more appropriate to
project the higher limit using the following options.
Under option 1, the ratio determined above would be applied to the
average PM emissions over time determined by the PM CEMS instead of
applying the ratio directly to the unadjusted PM CEMS limit itself. The
product of the ratio and the average PM emissions would then be
subtracted from the average emissions to determine the correction to
the PM CEMS operating parameter limit. This correction would then be
added to the PM CEMS operating parameter limit to determine the revised
PM CEMS operating parameter limit. Using the example described above
and assuming average PM CEMS emissions are 2 mg/dscm, the lowest ratio
(6.8 for PM) would be multiplied by the average PM emissions (2x6.8 =
13.6) and the average emissions would be subtracted from this product
(13.6-2). This difference (11.6) would be added to the PM CEMS
operating parameter limit to obtain the revised PM CEMS operating
parameter limit.
Under option 2, the PM CEMS recordings during the performance test
would be analyzed to calculate a PM CEMS operating parameter limit and
that limit would be increased by the factor defined by the ratio
discussed above (e.g., 6.8 in the first example). This approach would
ensure that infrequent high PM episodes that occurred over months of
CEMS operations would not be driving a PM CEMS limit that was then
projected further upward using the factors discussed above (unless
those high PM episodes actually occurred during the performance test).
Given the truncated emissions database (i.e., the performance test) for
calculating the higher projected limit under this option, however, the
limit may in fact be lower than the limit normally calculated from the
full CEMS emissions database (i.e., without attempted to project a
higher limit). In this case, the limit which is numerically higher
would be used.
The Agency requests information on which approach would be more
appropriate for projecting a higher PM CEMS operating parameter limit.
c. Ensuring that the higher projected PM CEMS operating parameter
limit
[[Page 67800]]
does not exceed the MACT PM standard. The PM CEMS operating parameter
limit would also be used to ensure compliance with the MACT PM
standard. We reiterate that the PM CEMS operating parameter limit is
not a measure of the emissions standard--the emissions standard is
defined in the rule as being measured by using manual methods--it is
instead an operating parameter limit used to ensure compliance with the
applicable standards. As discussed in section 1, above, it is likely
that due to several factors the PM CEMS operating parameter would have
a different numerical value that the MACT PM standard.
One reason for different numerical values is the use of different
techniques (i.e., one is manual methods based while the other is CEMS-
based) to determine a PM emissions value. The use of a manual method
test to determine a value is only a limited-time (e.g., 3 to 24 hours
every five years) measure of emissions, whereas a CEMS is a continuous
measure of emissions (e.g., 1 minute readings all the
time). Although the manual method will likely be a measure of ``high-
end'' PM emissions during performance testing, it may not account for
all potential variability during normal operations. The use of a CEMS
to monitor PM emissions is a way to continuously measure the
variability of (both low and high) PM emissions, inherent in any
engineered system.
Additionally, different values may be a result of the different
averaging periods stated for manual methods-based PM standard and the
PM CEMS operating parameter limit. See section 4, above, for a
discussion of the interrelationship between a numerical value of a
limit or standard and the averaging period. Having a PM CEMS operating
parameter limit with a different, possibly higher, numerical limit is
permissible and does not negate the value of the PM CEMS operating
parameter, provided there is reasonable correlation between the
operating parameter and the MACT PM standard. This section explains how
EPA would ensure that the numerically larger, revised PM CEMS operating
parameter limit would not violate the national PM standard.
Ensuring that the higher projected PM CEMS operating parameter
limit does not exceed the MACT PM standard is complicated by the fact
that the PM operating parameter limit would be CEMS-based while the
MACT PM standard would be manual method-based. Nonetheless, compliance
with the MACT PM standard can be ensured by limiting the increase in
the PM CEMS operating parameter limit (i.e., the projected PM CEMS
operating parameter limit divided by the limit prior to projection) to
the ratio of the MACT PM standard to the performance test PM level on a
manual method basis. Given that projections rather than measured values
would be used to ensure compliance with a standard, it may be prudent
to limit the increase in the projected PM CEMS operating parameter
limit to the ratio of 75% of the MACT PM standard to the performance
test PM level. A conservative factor of 75% is within the range of
reasonable values the Agency could have selected--50% to 100%.
Regarding the specific percentage EPA chooses, the reader is referred
to the previous discussion regarding the percentage EPA chooses for the
HAP standards that require PM control to ensure compliance.
Using the example from above and making the same assumptions, the
ratios would be calculated using 75 /dscm, 41/dscm,
and 26 mg/dscm in the numerator for SVM, LVM, and PM. These values are
75% of the standards for incinerators EPA discussed in the May 2, 1997,
HWC NODA. The resulting rations would be 7.5, 5.9, and 5.1. Since the
ratio calculated for PM is the lowest, ratio used to determine the
revised PM CEMS operating parameter limit would be 5.1.
d. Establishing Revised Operating Parameter Limits for the PM
Control Device Corresponding to the Higher Projected PM CEMS Operating
Parameter Limit. Ideally, PM control device operating parameter limits
(e.g, pressure drop across a fabric filter) should be established to
ensure compliance with the higher projected PM CEMS operating parameter
limit for compliance purposes while the CEMS is malfunctioning. Absent
these revised (i.e., less stringent) operating parameter limits, the
source would be required to: (1) Comply with the more stringent
operating parameter limits established during the performance test that
correspond to the original PM CEMS operating parameter limit; or (2)
ensure that a back-up CEMS is always available.
The Agency is considering an approach to establish revised
operating parameter limits for the PM control device corresponding to
operations at the higher projected PM CEMS operating parameter limit.
Under this approach, the source would analyze the historical operating
parameter values during those periods of time that PM emissions were
close to the higher projected PM CEMS operating parameter limit. Issues
that must be addressed, include: (1) What range of PM CEMS operating
parameter limit values should be considered to develop the database for
PM control device operating parameter values; and (2) how should the
database be analyzed to identify appropriate limits.
It may be appropriate to establish the revised PM control device
operating parameter limits based on the 90th percentile of values that
occur when PM levels are within 75% of the higher projected PM CEMS
operating parameter limit. This would help ensure that a significant
data set was available for evaluation and that the limits were not
based on the most lenient values recorded. This is important because
the higher projected PM CEMS operating parameter limit is likely to be
well beyond the calibration curve. 24
---------------------------------------------------------------------------
\24\ A source would be allowed to operate infrequently at levels
approaching a higher, projected PM CEMS operating parameter limit
that is beyond the calibration curve. If, however, a source operates
for prolonged periods at levels above the calibration curve, it must
perform Method 5 tests at those higher concentrations and include
those higher PM levels in the POM CEMS calibration. See discussion
on extrapolating PM CEMS calibration data elsewhere in today's
notice.
---------------------------------------------------------------------------
Based on further analysis, the Agency may consider other approaches
to define an appropriate data set of PM control device operating limits
and identify appropriate limits (e.g., considering a different
percentage of the historical data and/or basing the limit on a
different percentile of data). Alternatively, the Agency may conclude
that these approaches to revise the performance test-based operating
parameter limits would be too complicated or difficult for regulatory
officials to oversee, or that it would be difficult to confirm
compliance with the standards. In this event, sources would be required
to continue to comply with the PM control device operating parameter
limits established during the performance test when the CEMS
malfunctions even though the PM CEMS operating parameter limit has been
projected upward under procedures discussed above.
e. Implementing the Variance. Sources requesting the variance to
project a higher PM CEMS operating parameter limit would include the
request with the Certification of PM CEMS Performance (CoP) that would
be submitted within 12 months after the Compliance Date. The variance
request must include documentation of the analyses described above to
identify the higher projected PM CEMS operating parameter limit and the
revised, PM control device operating parameters associated with the
higher projected PM
[[Page 67801]]
operating parameter limit. Sources would be allowed to comply with the
higher projected PM CEMS operating parameter limit immediately upon
submitting the CoP. Regulatory officials would have three months to
review the variance request, however, and to notify the source of
intent to disapprove the higher projected PM CEMS operating parameter
limit (or the associated revised PM control device operating parameter
limits for use during CEMS malfunctions). In such cases, the regulatory
officials would provide the basis of their initial decision and provide
the source with an opportunity to present, within 30 calendar days,
additional information before final action on the variance.
7. EPA's PM CEMS Testing Program to Identify a CEMS-Based Emission
Level Achievable by MACT-Controlled Sources
The Agency is undertaking an additional PM CEMS testing program to
identify CEMS-based emission levels that are achievable by hazardous
waste combustors (i.e., hazardous waste burning incinerators, cement
kilns, and lightweight aggregate kilns) using MACT control. The testing
is scheduled to begin in December 1997 and results should be analyzed
by December 1998. The Agency is working with representatives of the
regulated community to identify one source in each of the three source
categories that is using MACT control and that would be likely to
define the most achievable level (i.e., considering average PM
emissions and emissions variability) for MACT-controlled sources.
Although these test results will not be used as part of the final
rule, the data will be valuable to permitting authorities and the
regulated community as a PM CEMS emission benchmark that is achievable
using MACT controls. Permitting authorities could use the data to
identify sources that appear to have established an anomalously high
CEMS-based PM operating parameter limit, and as a framework within
which to review Certifications of Performance in a cost-effective
manner. Likewise, sources wanting to ensure that their facility is
operating in a manner representative of MACT control could use this
information to see if their CEMS-based PM operating parameter limits
are below the levels that MACT sources show are achievable using MACT
control.
C. RCA Test Frequency
In the proposed rule, EPA said that facilities would be required to
perform relative calibration audits (RCAs) on their PM CEMS every 18
months. This testing interval would be relaxed to 30 months for small
on-site incinerators. These time intervals coincided with the proposed
Performance Test intervals. If these tests can be performed at the same
time as the performance tests, cost savings can be realized by the
facility relative to what the costs would be if the tests were not
conducted at the same time. As a result of the analysis of comments on
the performance test frequency, the Agency is considering requiring all
facilities to conduct comprehensive performance tests every five (5)
years. Therefore, we prefer that RCA tests be performed every five
years.
One of the goals of the PM CEMS Demonstration Test program was to
quantitatively define what RCA frequency is appropriate for PM CEMS.
Unfortunately, variability in the manual method masks any error that
can be identified as being caused by drift in the PM CEMS over time.
Therefore, we are unable to use the PM CEMS data from the demonstration
tests to extrapolate to an appropriate re-test frequency \25\.
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\25\ In fact as method accuracy improved, the PM CEMS
calibration statistics got better over time. Extrapolating this data
would lead to erroneous conclusion that no retesting is ever needed,
since the PM CEMS calibration keeps getting better.
---------------------------------------------------------------------------
Lacking these long-term data, it is important to look at what is
done in other countries to qualitatively determine this RCA test
frequency. The United Kingdom (UK) requires that retesting be conducted
at least every year, and in Germany testing is required every 3 to 5
years. The RCA test frequency could therefore reasonably be between one
and five years. The UK, though, heavily relies on manual methods
testing--so much so that they believe using gas bottles is cost
prohibitive for gaseous (e.g., NOx and SOx) CEMS
testing and rely on manual methods testing instead. EPA is inclined to
believe that the German's longer retest frequency is more consistent
with our regulatory framework.
D. Extrapolating PM CEMS Calibration Data
One-minute or batch PM CEMS readings during the course of
operations are likely to occasionally exceed the highest M5i
calibration point during the course of PM CEMS use. This is because the
manual method results used to derive the calibration are (nominally)
one hour block averages of emissions over the sampling period while the
PM CEMS readings are averages of emissions on the order of minutes. See
section 4, above, regarding the interrelationship the numerical limits
of a standard or limit and its associated averaging period. In
addition, emissions variability within the sampling period of M5 is not
likely to represent the full range of emissions variability over all
periods of PM CEMS operation. Therefore, a system is needed to allow
the extrapolation of data beyond the calibration curve.
The revised calibration and implementation scheme described in
today's notice (i.e., multiple calibrations (for light-scattering PM
CEMS) over the full range of emissions at the facility) will result in
a calibration from which some reasonable and limited extrapolation is
reasonable. Therefore, the Agency proposes to allow the calibration
curve to be used for measurements up to 25% more than the maximum M5
\26\ measurement observed during the calibration. (This will be
referred to as the ``125% point.'') Beyond this point (125% of the
highest M5 measurement) EPA is concerned that extrapolating the
calibration data might lead to false compliance determinations.
Therefore, some environmentally conservative approach must be employed.
---------------------------------------------------------------------------
\26\ In this context, M5 is meant to refer to all the methods
(Method 5, Method 5A, . . ., Method 5I) used to calibrate PM CEMS.
---------------------------------------------------------------------------
Note that the ability to extrapolate beyond the calibration curve
in no way would mitigate the facility's requirement to calibrate over
its full range of PM emissions. If a facility experiences continuous
periods of PM emissions beyond the calibration curve, it would be
obligated to perform tests to capture these data into the calibration
curve. For example, a facility may determine that it occasionally has
several continuous hours of PM CEMS readings which are greater than the
125% point. Several continuous hours are enough time to conduct a M5
test, so the facility would be obligated to conduct M5 tests at this
emissions level and include these data in the calibration curve used at
the facility. EPA requests comment on how long a period of sustained
operations at emissions levels greater than the 125% point would be
necessary to require these additional calibration data points.
1. Extrapolating Light-Scattering PM CEMS Calibration Data
If it is necessary to extrapolate beyond the 125% point, an
environmentally conservative approach would consist of determining the
slope of the calibration curve at the 125% point and have the
calibration continue with a slope equal to or greater than the slope of
the curve at the 125% point. For example if the
[[Page 67802]]
curve is a log-normal relation, the slope of the curve at the 125%
point would be positive, but less than the slope of a straight line
that would also describe the correlation between method results and PM
CEMS outputs. Therefore, if a log-normal relationship best describes
the calibration curve, facilities should extrapolate beyond the 125%
point using a straight line beyond the 125% point. The slope of the
straight line would be the slope of the log-normal curve, taken from
the points on the calibration curve associated with the lowest M5
measurement and the 125% point.
If the calibration curve is best described by a straight line
arithmetic fit, then extrapolating beyond this 125% point would depend
on the slope of any quadratic fit of the data. If the quadratic curve
slopes negative at higher values of PM CEMS outputs, then the straight
line defined by the calibration would be used to extrapolate beyond the
125% point. If the quadratic fit slopes positive at higher values of PM
CEMS outputs, then the quadratic fit would be used beyond the 125%
point.
Finally, if the calibration curve is a quadratic fit, then the
quadratic fit can be used to extrapolate all data \27\.
---------------------------------------------------------------------------
\27\ Note: If the slope of the quadratic fit is ever less than
zero for values of PM CEMS output above what was measured by the
manual method (that is, it ever has a negative slope), this
indicates that the correlation between M5 measurements and PM CEMS
output is not represented by a quadratic fit and that another
mathematical model should be used.
---------------------------------------------------------------------------
2. Extrapolation of Beta-gage Calibration Data
For Beta-gage PM CEMS, extrapolating beyond the 125% point would
involve continuing the straight line defined by its linear calibration
equation. Beta-gage PM CEMS apparently are not sensitive to particle
changes in the physical characteristics of particulate, as the light-
scattering PM CEMS are. Therefore, a straight-line fit best represents
the calibration for beta-gage PM CEMS at all times.
E. Need to Calibrate to Twice the Emissions Standard
One issue raised by commenters during the comment period for the
proposed rule was EPA's proposal that facilities calibrate the PM CEMS
to twice the emissions limit. Commenters raised concerns that
facilities might not be able to emit PM at a concentration equal to
twice the standard. They also said this aspect of the proposal in
essence asks facilities to violate the emission standard and could lead
to an enforcement action against the facility. Commenters also had
concerns that facility personnel may not be sufficiently familiar with
the various process and APCD factors to acceptably calibrate the PM
CEMS over the full range of operations experienced at the facility.
Each of these points are discussed in the following paragraphs.
EPA agrees that it would be difficult for many facilities to emit
PM at any prescribed level. Many facilities have redundancies in their
PM APCDs to such an extent that emitting to the emissions limit may be
problematic. However to have accurate PM CEMS measurements, facilities
need to calibrate the PM CEMS over the full range of emissions
experienced at the facility. As a result, it would be necessary to
require facilities to calibrate the PM CEMS over the full range of
operations, including PM emissions. This would eliminate the
prescriptive nature of how high the calibration needs to be while still
addressing the issue that the site-specific calibration of PM CEMS
covers the broad range of PM emissions experienced at the facility.
EPA does not agree, however, that this approach could cause
facilities to violate the manual method MACT PM standard. The PM
standard would be defined as the average of three manual method
measurements. Any single run above the standard would not be a
violation by itself. Average emissions over the calibration would be
below the standard for a source equipped with MACT controls. Therefore,
we expect that sources would be able to calibrate PM CEMS at levels
higher than the PM emissions standard and still remain in compliance
with the standard. If this is not practical, however, EPA may consider
a waiver of the manual method PM standard during periods of calibrating
(and performing RCA tests of) the PM CEMS. The need to obtain and audit
an accurate calibration at and above the PM standard may override any
concerns about high short-term PM emissions. EPA would want to limit
the frequency and duration of calibration runs that exceed the
standard, however. We request comment regarding how such limits could
be implemented. One way this could occur is to require that sources
request in the performance test plan approval to exceed the standard
during calibration. Approval to exceed the standard would only be
required if the average of all PM CEMS calibration runs is greater than
the PM standard.
The revised draft PS 11 states that different PM levels should be
obtained by varying process conditions or, alternatively, by adjusting
the APC system. It is relatively silent in presenting a well-defined
protocol with guidelines on how EPA expects calibration tests to be
performed. This is because individual sources should know best how to
vary their PM emissions. For instance, inserting a throttle plate in
lieu of one (or several) bags in a baghouse and varying the opening of
the throttle plate(s) is likely an effective way to vary PM
concentration for the calibration at a facility equipped with a
baghouse. Varying power to an ESP and simulating various failure modes
(such as lowering the temperature in the ESP to cause condensation on
the plates) is likely vary PM sufficiently for the calibration at
sources equipped with an ESP.
The experience gained during the PM CEMS Demonstration tests
suggests that one can obtain a suitable range of emissions by varying
process conditions that affect inlet PM loading to the last in a series
of PM APCDs and adjusting the performance of that last APCD. Exactly
how this is accomplished at a given facility will vary and depend on
the waste fed to the unit, how the facility is designed and operated,
and in what order the APCDs are configured. Therefore, the language in
the revised PS11 is adequate. More prescriptive language may not work
in most cases.
Finally, EPA, will be working with industry representatives to
develop approaches to better describe how calibration tests should be
performed at individual HWC facilities. EPA expects to provide this
information in a technical implementation guide.
F. Allowing PM CEMS to be Used In-lieu of Method 5 Tests
Although the PM CEMS would be required only as an operating
parameter, EPA intends to allow facilities to voluntarily elect to use
the PM CEMS for compliance with manual methods-based PM standards.
Using the PM CEMS for compliance is expected to provide a cost savings
to the facility since the facility would not have to conduct periodic
Method 5 tests to document compliance with PM standards. Instead a
facility could elect to use the PM CEMS measurements during these
periodic tests. This would be acceptable if the facility uses the block
average of the PM CEMS readings during the M29 tests for the SVM and
LVM standards as the particulate ``method result.''
G. Waivers from the PM CEMS Requirements
In the proposed rule, EPA requested comment on waiving the PM and
Hg CEMS requirement for small, on-site incinerators. See 61 FR at
17439. Upon
[[Page 67803]]
further consideration, EPA has identified other classes of incinerators
where a PM CEMS requirement may be impractical. If the PM CEMS
requirement is waived for a given source, the facility would have to
comply with operating parameter limits to assure compliance for PM. Of
course, a facility could always elect to use a PM CEMS for compliance
even if a waiver procedure is promulgated for that facility.
1. Waiver of PM and Hg CEMS Requirements for Small On-site Incinerators
EPA is considering whether to waive the PM and Hg CEMS requirements
for small, on-site incinerators (SOSI). See the proposed rule, 61 FR at
17439. If a waiver is promulgated, a SOSI would be required to use
existing operating parameters in lieu of a PM CEMS to document
compliance with the PM, SVM, and LVM standards.
2. PM CEMS Waiver for Sources With Short Life-Spans
Given the PM CEMS compliance schedule discussed in section IV.A,
above, facilities with short, fixed life-spans raise several issues.
For instance, certain government-run incinerators are constructed for
the purposes of destroying waste that is too hazardous to transport
off-site. These incinerators often have short life spans (ranging from
months to a few years) and are constructed to fulfill the requirements
of a consent decree, memorandum of understanding (MOU), or other
legally binding enforcement agreement. For example the Department of
Defense (DoD), acting under a MOU with EPA, may construct an
incinerator to destroy nerve-gas agents that are too hazardous to
transport. When this activity is complete, the MOU would obligate DoD
to dismantle and destroy the incinerator.
It does not seem practical to mandate that these facilities use PM
CEMS if they will be in service for less than, or slightly longer than,
the implementation schedule just discussed. Therefore, EPA is
considering a waiver of the PM CEMS requirement for HWCs operating
under a legally binding agreement that ensures the source will stop
burning hazardous waste within three years of the Compliance Date.
EPA could likewise grant a waiver from the PM CEMS requirement for
facilities with short life-spans that lack the legally binding
agreement discussed above. However, EPA is concerned that without a
legally binding agreement to cease operations, the Agency lacks
certainty that operations will cease by a prescribed date. For this
reason, EPA would consider a waiver for other facilities that plan to
cease operations within the first year of compliance with the HWC
regulations, that is, prior to the need to use PM CEMS as the operating
parameter for PM control. Facilities that operate after the first year
would need to have PM CEMS installed, calibrated, meet data
availability requirements, determine the PM CEMS operating parameter
limit, and use the PM CEMS as the primary operating parameter for PM
control.
3. Other Sources
As discussed in section III.C. of this NODA, EPA may be unable to
determine whether the results of the PM CEMS demonstration test can be
transferred to two classes of incinerators: Those with waste heat
boilers and mobile incinerators. See section III.C. for more
information.
V. Other Issues Concerning CEMS and Test Methods for HWCs
A. Performance Specifications for Optional CEMS
In the proposed rule, EPA proposed other performance specifications
for multi-metals, hydrochloric acid (HCl), and chlorine gas
(Cl2) CEMS. These performance specifications were proposed
as PS10, 13, and 14, respectively. Based on what EPA has learned during
the course of demonstrating PM and Hg CEMS, EPA expects not to
promulgate the draft performance specifications (PS) for these CEMS at
the time of the HWC final rule. As discussed in section II of today's
notice, EPA does not plan to promulgate a PS for total mercury (Hg)
CEMS either. The Agency has not tested MM and Cl2 CEMS to
determine what performance is achievable by the CEMS. Hg CEMS have not
been demonstrated as a compliance tool for universal application to all
HWCs. EPA has tested HCl CEMS in preparation for the medical waste
incinerator rulemaking but did not require the use of HCl CEMS in that
rulemaking (see discussion starting at 62 FR 48360, September 15, 1997)
and does not believe requiring HCl CEMS for the HWC rulemaking is
appropriate either (see 61 FR at 17433).
Instead, EPA will consider enabling sources to demonstrate these
CEMS on a site-specific basis and to develop performance levels for the
CEMS as part of the demonstration. The Agency's only concern is that
the CEMS be proven to be a better and more reliable indicator of
compliance for the HAP or standard than the requirements specified in
the regulations. This approach is now being used to demonstrate a
multi-metals CEMS at the Von Roll incinerator in East Liverpool, Ohio.
EPA intends to accumulate the CEMS demonstration results and
experience and will share that information with permitting authorities
and sources wishing to document compliance with CEMS. Since the HCl
CEMS have been demonstrated by EPA, we believe the HCl CEMS performance
specification could more easily be used as a point of departure for
implementing HCl CEMS at a given facility.
B. Stack Sampling Test Methods
Another question is whether EPA should simplify the task of
determining the appropriate manual method tests to be used for
compliance. Currently, stack sampling and analysis methods for HWCs are
(with a few exceptions) located in RCRA's SW-846 for compliance with
the BIF and incinerator rules, and in 40 CFR part 60, Appendix A for
compliance with the NSPS and other air rules. Facilities could be
required to perform two identical tests, one for compliance with MACT
or RCRA and one for compliance with other air rules, using identical
test methods simply because one method is an ``SW-846'' method and the
other an ``air method.''
Stack test methods HWCs use for compliance should be found in one
place to facilitate compliance. EPA intends to reference 40 CFR part
60, Appendix A, when it requires a specific stack-sampling test method.
A few SW-846 methods do not have equivalents in 40 CFR part 60,
Appendix A, namely the VOST and semi-VOST methods. In these few cases,
EPA would continue to refer to these SW-846 methods as well.
This discussion only affects stack sampling methods and has no
affect on feedstream sampling and analysis.
Dated: December 19, 1997.
Matt Hale,
Acting Director, Office of Solid Waste.
Appendix I--Method 5i
Method 5I--Determination of Low Level Particulate Matter Emissions From
Stationary Sources
1. Applicability and Principal
1.1 Applicability. This method applies to the determination of
low level particulate matter (PM) emissions from stationary sources
and facilities performing calibrations or calibration audits of
particulate matter continuous emission monitors as specified in the
regulations. The method is effective for total train catches of 50
mg or less. The minimum detection limit for this method can be
determined by repeatedly collecting and analyzing blank samples. A
blank sample is a sample of blank air collected and analyzed
[[Page 67804]]
in the normal manner. The limit of detection can be calculated by
collecting and analyzing seven blank samples and then calculating an
estimate of the sample standard deviation of these blanks. The limit
of detection would be three times the estimated sample standard
deviation.
1.2 Principal. The PM is withdrawn isokinetically from the
source and collected on a 47 mm glass fiber filter maintained at a
temperature of 120 deg. 14 deg.C (248 deg.
25 deg.F). The PM mass, which includes any material that
condenses at or above the filtration temperature, is determined
gravimetrically after the removal of uncombined water.
2. Apparatus
2.1 Sampling Train. The sampling train configuration is the
same as shown in Method 5, Figure 5-1. The sampling train consists
of the following components: Pitot Tube, Probe liner Differential
Pressure Gauge, Filter Heating System, Condenser, Metering System,
Barometer, and Gas Density Determination Equipment. Same as Method
5, Sections 2.1.2 to 2.1.4, 2.1.6 and 2.1.7 to 2.1.10, respectively.
2.1.1 Probe Nozzle. Same as Method 5, Sections 2.1.1 with the
exception that it is constructed of Borosilicate or quartz glass
tubing with sharp, tapered leading edge.
2.1.2 Filter Holder. The filter holder for this sampling train
is constructed of Borosilicate or quartz glass front cover designed
to hold a 47 mm glass fiber filter, with a stainless steel filter
support, a silicone rubber or Viton O-ring and Teflon tape seal. The
holder design will provide a positive seal against leakage from the
outside or around the filter. The filter holder assembly fits into a
stainless steel filter holder and attaches immediately at the outlet
of the probe (or cyclone, if used). The tare weight of the filter,
Borosilicate or quartz glass, stainless steel filter support,
silicone rubber or Viton O-ring and Teflon tape seal will not exceed
31 grams. The filter holder is designed to use a 47 mm glass fiber
filter meeting the criteria in section 3.1.1 of Method 5. Figure 5I-
1 presents a schematic of the filter holder system. These units are
commercially available.
2.1.3 Glass Plugs and Clamps. Once the filter holder has been
assembled, desiccated and tared it is critical that the filter be
isolated from any external sources of contamination. This can be
accomplished by covering the leak-free ground glass or O-ring socket
on the front half glass filter cover with a Borosilicate or quartz
ground glass plug. The plug shall be secured in place with the
appropriate sized laboratory impinger clamp or any system that can
ensure a leak-free fitting. It is beneficial to place the glass plug
on the inlet socket as soon as the unit is assembled, however do not
tare the assembly with the plug in place, as this will increase the
tare weight introducing additional error into the final weighings.
2.2 Sample Recovery. Is the same as Method 5 for: Glass Sample
Storage Containers, Graduated Cylinder and/or Balance, Plastic
Storage Containers, Funnel and Rubber Policeman (Method 5 sections
2.2.3, 2.2.5--2.2.8, respectively) with the following exceptions:
2.2.1 Probe-Liner and Probe-Nozzle Brushes. Teflon
and nylon bristle brushes with stainless steel wire handles, should
be used to clean the probe. The probe brush shall have extensions
(at least as long as the probe) of Nylon, Teflon, or
similarly inert material. The brushes shall be properly sized and
shaped to brush out the probe liner and nozzle.
2.2.2 Wash Bottles--Two. Teflon wash bottles are
recommended however, polyethylene wash bottles may be used at the
option of the tester. It is recommended that acetone not be stored
in polyethylene bottles for longer than a month.
2.2.3 Sample Holder: A portable carrying case with clean
compartments of sufficient size to accommodate each filter assembly.
The filters shall be able to lay flat with the stainless steel
filter support placed down in the compartment. This system should
have an air tight seal to prevent contamination to the filters
during transport to and from the field. It is recommended that
desiccant be used in this case. The desiccant, if used, is housed in
a container that is capped with a 0.1 micron screen to ensure that
no dust particles can contaminate the outside of the filter housings
during transport.
2.3 Analysis. The same as Method 5 for sections 2.3.2-2.3.7
with the following exception:
2.3.1 Teflon Liner: Teflon liners are used for the
analysis of the probe and nozzle particulate catch. The liners are
washed with soap (Alconox or similar low residue laboratory soap)
and water. Each liner is then rinsed with DI Water followed by an
acetone (low residue) rinse. The static charge on the liners is
removed using an anti-static rinse and then the liners are oven
dried and desiccated.
3. Reagents
3.1 Sampling. The reagents used in sampling are the same as
Method 5 for: Silica Gel, Water, Crushed Ice, Sample Recovery
Reagents, and Desiccant (sections 3.1.2-3.1.5, 3.2-3.3.2) with the
following exceptions:
3.1.1 Filters. 47 mm Glass fiber filters, without organic
binder, exhibiting at least 99.95 percent efficiency (<0.05 percent="" penetration)="" on="" 0.3-micron="" dioctyl="" phthalate="" smoke="" particles.="" the="" filter="" efficiency="" test="" shall="" be="" conducted="" in="" accordance="" with="" astm="" standard="" method="" d2986-71="" (reapproved="" 1978)="" (incorporated="" by="" reference--see="" sec.="" 60.17).="" test="" data="" from="" the="" supplier's="" quality="" control="" program="" are="" sufficient="" for="" this="" purpose.="" in="" sources="" containing="">2 or SO3, the filter material
must be of a type that is unreactive to SO2 or
SO3. Citation 10 in the Bibliography for Method 5, may be
used to select the appropriate filter.
3.1.2 Stopcock Grease. Stopcock grease cannot be used with this
sampling train. It is recommended that the sampling train be
configured with glass joints, using o-ring seals or screw-on
connectors with Teflon sleeves, or similar.
3.1.3 Acetone. Pesticide grade or equivalent low residue type
Acetone is used for the recovery of particulate matter from the
probe and nozzle.
3.1.4 Latex Gloves. Disposable, powder free, latex surgical
gloves are used for all handling of the filter housings at all
times.
4. Procedure
4.1 Sampling. The complexity of this method is such that, in
order to obtain reliable results, testers should be trained and
experienced with the test procedures. The sampling procedures are
the same as Method 5 for: Preliminary Determinations, Leak-Check
Procedures, Particulate Train Operation (sections 4.1.2, 4.1.4,
4.1.5 respectively ) with the following exceptions:
4.1.1 Pretest Preparation. Is the same as Method 5, section
4.1.1 with the following exception: Label filter supports prior to
loading filters into the holder assembly. This can be accomplished
with a diamond scribe. As an alternative, label the shipping
container compartments (glass or plastic) and keep the filter holder
assemblies in these compartments at all times except during sampling
and weighing. Using the powder free latex surgical gloves (surgical
gloves must be used at all times when handling the filter holder
assemblies). Place the Viton O-ring on the back of the
filter housing in the O-ring grove. Place a 47mm glass fiber filter
on the O-ring with the face down. Place a stainless steel filter
holder against the back of the filter. Carefully wrap \1/4\ inch
wide Teflon tape one time around the outside of the
filter holder overlapping the stainless steel filter support by
approximately \1/8\ inch. Gently brush the Teflon tape
down on the back of the stainless steel filter support. Desiccate
the filter holder assemblies at 205.6 deg. C
(6810 deg. F) and ambient pressure for at least 24 hours
and weigh at intervals of at least 6 hours to a constant weight,
i.e., 0.5 mg change from previous weighing; record results to the
nearest 0.1 mg. During each weighing the filter holder assemblies
must not be exposed to the laboratory atmosphere for a period
greater than 2 minutes and a relative humidity above 30 percent.
Alternatively (unless otherwise specified by the Administrator), the
filters holder assemblies may be oven dried at 105 deg. C (220 deg.
F) for 2 to 3 hours, desiccated for 2 hours, and weighed.
4.1.2 Same as Method 5, section 4.1.2.
4.1.3 Preparation of Collection Train. Is the same as Method 5,
section 4.1.3 with the following exception: During preparation and
assembly of the sampling train, keep all openings where
contamination can occur covered until just prior to assembly or
until sampling is about to begin. Using clean disposable powder free
latex surgical gloves, place a labeled (identified) and weighed
filter holder assembly in the stainless holder for the assembly.
Then place this whole unit in the Method 5 hot box and attach it to
the probe using clean standard connectors. Do not use any stopcock
grease.
4.2 Sample Recovery. Proper cleanup procedure begins as soon as
the probe is removed from the stack at the end of the sampling
period. Allow the probe to cool. When the probe can be safely
handled, wipe off all external particulate matter near the tip of
the probe nozzle and place a cap over it to prevent losing or
gaining particulate matter. Do not cap off the probe tip tightly
while the sampling train is cooling down as this would create a
vacuum in the filter holder, thus drawing water from the impingers
into the filter holder. Before
[[Page 67805]]
moving the sample train to the cleanup site, remove the probe from
the sample train and cap the open outlet of the probe. Be careful
not to lose any condensate that might be present. Cap the filter
inlet using a standard ground glass plug and secure the cap with an
impinger clamp. Remove the umbilical cord from the last impinger and
cap the impinger. If a flexible line is used between the first
impinger or condenser and the filter holder, disconnect the line at
the filter holder and let any condensed water or liquid drain into
the impingers or condenser. Transfer the probe and filter-impinger
assembly to the cleanup area. This area should be clean and
protected from the wind so that the chances of contaminating or
losing the sample will be minimized. Save a portion of the acetone
used for cleanup of the probe and nozzle as a blank. Take 200 ml of
this acetone directly from the wash bottle being used and place it
in a glass sample container labeled ``acetone blank.'' Inspect the
train prior to and during disassembly and note any abnormal
conditions. Treat the samples as follows:
Container No. 1. Carefully remove the filter holder assembly
from the Method 5 hot box and place it in the transport case. Use a
pair of clean disposable powder free latex surgical gloves to handle
the filter holder assembly. If the transport case is being used to
identify and track the filter holder assemblies the entire transport
container will need to be of sufficient size and shape to fit in the
desiccator at the laboratory. It is important to ensure that the
assemblies have cooled sufficiently to prevent the surgical gloves
from melting on the filter holder assembly.
Container No. 2. Same as Method 5 Container No. 2 with the
exception that it is recommended that only glass sample containers
be used for collection of the sample from the probe and nozzle to
minimize the potential for background contamination.
Container No. 3. Same as Method 5 Container No. 3.
4.3 Analysis. Same as Method 5 section 4.3 with the following
exceptions:
Container No. 1. Same as Method 5 Section 4.3 Container No. 1
with the following exception: Use disposable powder free latex
surgical gloves to remove each of the filter holder assemblies from
the desiccator or transport container.
Container No. 2. Same as Method 5 Section 4.3 Container No. 2
with the following exception: It is recommended that the contents of
Container 2 be transferred to a 250 ml beaker with a Teflon\ liner
or similar container that has a minimal tare weight prior to
bringing to dryness.
Container No. 3. Same as Method 5 Section 4.3 Container No. 3
4.4 Quality Control Procedures. The Quality Control Procedures
used in sampling are the same as Method 5 for: Meter Orifice Check
and Calibrated Critical Orifice (sections 4.4.1--4.4.2).
5. Calibration.
The Calibration Procedures used are the same as Method 5: Probe
Nozzle, Pitot Tube, Metering System, Probe Heater Calibration,
Temperature Gauges, Leak Check of Metering System Shown in Method 5
Figure 5-1, Barometer (sections 5.1--5.7).
6. Calculations
The Calculations used are the same as Method 5 for:
Nomenclature, Average Dry Gas Meter Temperature and Average Orifice
Pressure Drop, Dry Gas Volume, Volume of Water Vapor, Acetone Blank
Concentration, Total Particulate Weight, Particulate Concentration,
Conversion Factors, Isokinetic Variation, Acceptable Results, Stack
Gas Velocity and Volumetric Flow Rate (sections 6.1--6.13).
7. Alternative Procedures
The Alternative Procedures used are the same as Method 5 for:
Dry Gas Meter as a Calibration Standard, Critical Orifices As
Calibration Standards, (sections 7.1--7.2).
8. Bibliography
The Bibliography used is the same as Method 5.
BILLING CODE 6560-50-P
[[Page 67806]]
[GRAPHIC] [TIFF OMITTED] TP30DE97.028
BILLING CODE 6560-50-C
[[Page 67807]]
Appendix II--Performance Specification 11
PERFORMANCE SPECIFICATION 11--Specifications and test procedures for
particulate matter continuous emission monitoring systems in stationary
sources.
211.0 Scope and Application
1.1 Analyte. Particulate matter as defined and determined by
the Reference Method--Method 5 or Method 5I.
1.2 Applicability.
1.2.1 This specification is for evaluating the acceptability of
particulate matter (PM) continuous emission monitoring systems
(CEMS) at the time of or soon after installation and whenever
specified in the regulations. The CEMS may include, for certain
stationary sources, (a) a diluent monitor (i.e., O2, CO,
or other CEMS specified in the applicable regulation), which must
meet its own performance specifications found in this appendix, (b)
auxiliary monitoring equipment to allow measurement, determination,
or input of the gas temperature, pressure, moisture content, and/or
dry volume of stack effluent sampled, and (c) an automatic sampling
system.
This performance specification requires site specific
calibration of the PM CEMS response against manual gravimetric
Reference Method measurements. Procedures for extrapolating results
beyond the range of particulate mass loadings used to develop the
calibration are found in the applicable regulations. A new
calibration may be required if conditions at the facility change and
result in conditions which are unrepresentative of the previous
calibration (i.e., changes in emission control system, concentration
of PM emitted, or feed inputs to the device). Since the validity of
the calibration may be affected by changes in the physical
properties of the particulate (such as density, index of refraction,
and size distribution), the limitations of the CEMS used should be
evaluated with respect to these possible changes on a site specific
basis.
1.2.2 This specification is not designed to evaluate the
installed CEMS performance over an extended period of time nor does
it identify specific calibration techniques and auxiliary procedures
to assess CEMS performance. The source owner or operator, however,
is responsible to properly calibrate, maintain, and operate the
CEMS. The Administrator may require, under Section 114 of the Act,
the operator to conduct CEMS performance evaluations at other times
besides the initial test to evaluate the CEMS performance. See
Appendix F to Part 60--Procedure 2, Quality Assurance Requirements
For Particulate Matter Continuous Emission Monitoring Systems Used
For Compliance Determination.
2.0 Summary of Performance Specification.
Procedures for establishing the CEMS calibration are outlined in
this performance specification. CEMS installation and measurement
location specifications, equipment specifications, performance
specifications, and data reduction procedures are also included.
Conformance of the CEMS with the Performance Specifications is
determined.
3.0 Definitions
3.1 Batch Sampling means the technique of sampling the stack
effluent continuously and concentrating the pollutant in some
capture medium. The capture medium is moved periodically for
analysis after sufficient time has elapsed to concentrate the
pollutant to levels detectable by the analyzer. Continuous sampling
is ensured by sampling (either on a different part of the capture
medium or a different capture medium) while analysis is being
performed on a previous sample.
3.2 Calibration Drift (CD) means the difference in the CEMS
output readings from the established reference value after a stated
period of operation during which no unscheduled maintenance, repair,
or manual adjustment took place.
3.3 Calibration means the site-specific correlation between the
CEMS output and the PM mass concentration measured by the Reference
Method.
3.4 Calibration Standard means a reference material that
produces a known and unchanging response when presented to the
pollutant analyzer portion of the CEMS, and used to calibrate the
drift or response of the analyzer.
3.5 Centroidal Area means a concentric area that is
geometrically similar to the stack or duct cross section and is no
greater than 1 percent of the stack or duct cross sectional area.
3.6 Confidence Interval means the interval defined by equations
13 and 23 of this performance specification with upper and lower
limits within which the CEMS response calibration relation lies with
a given level of confidence.
3.7 Continuous Emission Monitoring System (CEMS) means the
total equipment required for the determination of particulate matter
mass concentration in units of the emission standard. The sample
interface, pollutant analyzer, diluent analyzer, other auxiliary
data monitor(s) and data recorder are the major subsystems of the
CEMS.
3.8 Correlation coefficient means that portion of the
statistical evaluation that measures how well the CEMS and Reference
Method calibration relation data fit the regression line as defined
by equation 16 of this performance specification.
3.9 Data Recorder means that portion of the CEMS that provides
a permanent record of the analyzer output and the final PM
concentration result in units of the emission standard. The data
recorder may provide automatic data reduction and CEMS control
capabilities.
3.10 Diluent Analyzer and Other Auxiliary Data Monitor(s) (if
applicable) means that portion of the CEMS that sense or otherwise
provide the diluent gas (such as O2 or CO, as specified
by the applicable regulations), temperature, pressure, and/or
moisture content, and generates an output proportional to the
diluent gas concentration or data property.
3.11 Linear Calibration means a CEMS response which is linear
relative to the measured PM concentration produced by the Reference
Method.
3.12 Path CEMS means a CEMS that measures particulate matter
mass concentrations along a path across the stack or duct cross
section which is representative of results of the cross-sectional PM
concentrations produced by the Reference Method.
3.13 Point CEMS means a CEMS that measures particulate matter
mass concentrations either at a single point, or over a small fixed
volume or path, which is representative of the cross-sectional PM
concentrations produced by the Reference Method.
3.14 Pollutant Analyzer means that portion of the CEMS that
senses the particulate matter concentration and generates a
proportional output.
3.15 Quadratic Calibration Relation means a CEMS response which
has a second order equation to define its relationship to the
measured PM concentration produced by the Reference Method.
3.16 Reference Method. The Reference Method for particulate
measurements is those methods collectively known as Method 5, found
in Appendix A of 40 CFR Part 60. Unless other variants are specified
in the regulations, Method 5 shall be used for total train catches
exceeding 50 mg (i.e., emissions concentrations of more than 45 mg/
dscm). Method 5I shall be used for total train catches of less than
or equal to 50 mg (i.e., emissions concentrations of 45 mg/dscm or
less). If variants other than Method 5I are used, care should be
taken to follow the general procedures described in Method 5I to aid
in the elimination of measurement error. Other Reference Methods may
be applicable, such as Method 1, 3, or 4. Methods other than Method
5 are referred to in this specification individually by name.
3.17 Representative Results means the results consistent with
the acceptance criteria found in section 13.2 of this specification.
3.18 Response Time means the time interval between the start of
a step change in the system input and the time when the pollutant
analyzer output reaches 95 percent of the final value.
3.19 Sample Interface means that portion of the CEMS used for
one or more of the following: sample acquisition, sample delivery,
sample conditioning, or protection of the monitor from the effects
of the stack effluent.
3.20 Span Value means the upper limit of the CEMS measurement
range. The span value shall be documented by the CEMS manufacturer
with laboratory data.
3.21 Tolerance Interval means the interval with upper and lower
limits within which are contained a specified percentage of the
population with a given level of confidence as defined by equation
14 of this performance specification.
3.22 Zero Drift (ZD) means the difference in the CEMS output
readings for zero input after a stated period of operation during
which no unscheduled maintenance, repair, or adjustment took place.
4.0 Interferences
In the Reference Method a representative sample of particulate
is collected on a filter maintained at a temperature in the range
[[Page 67808]]
specified by the method, and includes any material that deposits in
sample delivery and condenses at or above this filtration
temperature after removal of any combined water. Consequently,
condensible water droplets or condensible acid gas aerosols (i.e.,
those with condensation temperatures above those specified by the
method) at the measurement location can be interferences for PM CEMS
if the necessary precautions are not systematically met.
Interferences may develop for CEMS installed downstream of a wet air
pollution control system or any other conditions that produce flue
gases which are normally or occasionally saturated with water or
acid gases prior to release to the atmosphere. For such conditions,
the CEMS must extract and heat a representative sample of the flue
gas for measurement to simulate results produced by the Reference
Method. Independent of the CEMS measurement technology and
extractive technique, a configuration simulating the Reference
Method is required to assure that: (1) there is no formation or
deposition of particulate in sample delivery from the stack or duct;
and (2) the pollutant analyzer portion of the CEMS measures only
native particulate. Performance of a CEMS design configured to
eliminate interferences with condensible water and/or acid gases
must be documented by the CEMS manufacturer (see Section 6.1.3 of
this performance specification for specific equipment heating
requirements). In-situ CEMS measurement technologies that are not
free of interferences from any condensible constituent in the flue
gas are prohibited in stack or duct flue gas conditions which are
normally or occasionally saturated with water or acid gases.
5.0 Safety
The procedures required under this performance specification may
involve hazardous materials, operations, site conditions, and
equipment. This performance specification does not purport to
address all of the safety problems associated with these procedures.
It is the responsibility of the user to establish appropriate safety
and health practices and determine the applicable regulatory
limitations prior to performing these procedures. The CEMS users'
manual and materials recommended by the Reference Method should be
consulted for specific precautions to be taken.
6.0 Equipment and Supplies
6.1 CEMS Equipment Specifications
6.1.1 Data Recorder Scale. The CEMS data recorder output range
must include zero and a high level value. The high level value is
chosen by the source owner or operator and is defined as follows:
6.1.1.1 For a CEMS installed to measure emissions as required
with an applicable regulation, the high level value between 1.5
times the emission standard and the span value specified in the
applicable regulation is adequate.
6.1.1.2 Alternative high-level values may be used, provided the
source can measure emissions throughout the full range of emissions
concentrations experienced by the facility.
6.1.1.3 The data recorder output must be established so that the
high level value would read between 90 and 100 percent of the data
recorder full scale. (This scale requirement may only be applicable
to analog data recorders.) The zero and high level calibration gas,
filter, or other appropriate media values should be used to
establish the data recorder scale.
6.1.1.4 The high level value must be equal to the span value. If
a lower high level value is used, the CEMS must have the capability
of providing multiple outputs with different high level values (one
of which is equal to the span value) or be capable of automatically
changing the high level value as required (up to the span value)
such that the measured value does not exceed 95 percent of the high
level value.
6.1.1.5 Span. The span of the instrument shall be sufficient to
determine the highest concentration of pollutant at the facility.
The span value shall be documented by the CEMS manufacturer with
laboratory data.
6.1.2 The CEMS design should also allow daily determination and
recording of calibration drift at the zero and high-level values. If
this is not possible or practical, the design must allow these
determinations and recordings to be conducted at a low-level (zero
to 20 percent of the high-level value) and at a value between 50 and
100 percent of the high-level value. In special cases, the
Administrator may approve a single-point calibration drift
determination.
6.1.3 Specification for Saturated Flue Gas. For a CEMS installed
downstream of a wet air pollution control system such that the flue
gases are normally or occasionally saturated with water, then the
CEMS must have equipment to extract and heat a representative sample
of the flue gas for measurement so that the pollutant analyzer
portion of the CEMS measures only dry particulate. Heating shall be
sufficient to raise the temperature of the extracted flue gas to
above the water condensation temperature and shall be maintained at
all times and at all points in the sample line from where the flue
gas is extracted to and including the pollutant analyzer.
Performance of a CEMS design configured in this manner must be
documented by the CEMS manufacturer.
6.2 Sampling and Response Time. The CEMS shall sample the stack
effluent continuously or intermittently for batch sampling CEMS.
Averaging time, the number of measurements in an average, the
minimum sampling time, and the averaging procedure for reporting and
determining compliance shall conform with those specified in the
applicable emission regulation.
6.2.1 Response Time. The response time of the CEMS should not
exceed 2 minutes to achieve 95 percent of the final stable value
(except for Batch CEMS: see 6.2.2). The response time shall be
documented and provided by the CEMS manufacturer. Any changes in the
response time following installation shall be documented and
maintained by the facility.
6.2.2 Response Time for Batch CEMS. The response time
requirement of Section 6.2.1 does not apply to batch CEMS. Instead
it is required that the response time, which is the equivalent to
the cycle time, be no longer than one tenth of the averaging period
for the applicable standard or no longer than fifteen minutes,
whichever is greater. In addition, the delay between the end of the
sampling time and reporting of the sample analysis shall be no
greater than three minutes. Any changes in the response time
following installation shall be documented and maintained by the
owner or operator.
6.2.3 Sampling Time for Batch CEMS. Sampling is required to be
continuous except during brief pauses when the collected pollutant
on the capture media is being moved for analysis and the next
capture medium starts sampling. In addition, the sampling time
should be no less than thirty-five percent of the averaging period
for the applicable standard or no less than thirty-five percent of
the response time.
6.3 Other equipment and supplies, as needed by the applicable
Reference Method(s) (see Section 8.4.2 of this Performance
Specification) or as specified by the CEMS manufacturer, may be
required.
7.0 Reagents and Standards
7.1 Reference Gases, Optical filters, or other technology-
appropriate reference media. As specified by the CEMS manufacturer
for internal calibration (i.e., to adjust drift or response) of the
CEMS. These need not be certified but shall be documented by the
manufacturer to give results consistent with this performance
specification.
7.2 Reagents and Standards. May be required as needed by the
applicable Reference Method(s) (see Section 8.4.2) of this
performance specification).
8.0 Performance Specification Test Procedure
8.1 Installation and Measurement Location Specifications.
8.1.1 CEMS Installation. Install the CEMS at an accessible
location downstream of all pollution control equipment where the
particulate matter mass concentrations measurements are
representative or can be corrected to be representative of the total
emissions as determined by the Reference Method from the affected
facility or at the measurement location cross section. It is
important to select a representative measurement point(s) or path(s)
for monitoring in location(s) that the CEMS will pass the
calibration test (see Section 8.4). If the cause of failure to meet
the calibration relation test is determined to be the measurement
location and a satisfactory correction technique cannot be
established, the Administrator may require the CEMS to be relocated.
Suggested measurement locations and points or paths that are most
likely to provide data that will meet the calibration requirements
are listed below.
8.1.2 Measurement Location. It is suggested that the measurement
location be: (1) at least eight equivalent diameters downstream from
the nearest flow disturbance, such as a control device, point of
pollutant generation, bend, expansion, contraction in the stack/
duct, point of discharge, or other point at which a change of
pollutant concentration or gas streamlines may occur; and (2) at
least two equivalent
[[Page 67809]]
diameter upstream from the effluent exhaust or a flow disturbance.
8.1.2.1 Point CEMS. It is suggested that the measurement point
be: (1) no less than 30% of the stack or duct diameter from the
stack or duct wall; or (2) within or centrally located over the
centroidal area of the stack or duct cross section.
8.1.2.2 Path CEMS. It is suggested that the effective
measurement path be : (1) totally within the inner area bounded by a
line 30 percent of the stack/duct diameter from the stack or duct
wall; (2) have at least 70 percent of the path within the inner 50
percent of the stack or duct cross sectional area; or (3) be
centrally located over any part of the centroidal area.
8.1.3 Reference Method Measurement Location and Traverse Points.
8.1.3.1 Select, as appropriate: (1) an accessible Reference
Method measurement point at least eight equivalent diameters
downstream from the nearest flow disturbance, such as a control
device, point of pollutant generation, bend, expansion, contraction
in the stack or duct discharge point, or other point at which a
change of pollutant concentration or gas flow direction may occur;
and (2) at least two equivalent diameters upstream from the flow
disturbance, such as the effluent exhaust. When pollutant
concentration changes are due solely to diluent leakage (e.g., air
heater leakages) and pollutants and diluents are simultaneously
measured at the same location, a half diameter may be used in lieu
of two equivalent diameters. The CEMS and Reference Method locations
need not be the same so long as the Reference Method is placed at a
location specified by the method and the CEMS output is
representative of pollutant emissions determined by the Reference
Method.
8.1.3.2 Select traverse points that assure acquisition of
representative samples over the stack or duct cross section.
Selection of traverse points to determine the representativeness of
the measurement location should be made according to 40 CFR part 60,
Appendix A, Method 1, Section 2.2 and 2.3.
8.2 Pretest Preparation. Install the CEMS, prepare the
Reference Method test site according to the specifications in
Section 8.1, and prepare the CEMS for operation according to the
manufacturer's written instructions.
8.3 Calibration Drift Test Procedure.
8.3.1 CD test Period. While the affected facility is operating
more than 50 percent of normal load, or as specified in an
applicable Subpart, determine the magnitude of the CD once each day
(at 24-hour intervals) for 7 consecutive days according to the
procedure given in Sections 8.3.2 and 8.3.3.
8.3.2 The purpose of the CD measurement is to verify the
ability of the CEMS to conform to the established CEMS calibration
used for determining the emission concentration or emission rate.
Therefore, if periodic automatic or manual adjustments are made to
the CEMS zero and calibration settings, conduct the CD test
immediately before these adjustments, or conduct it in such a way
that the CD can be determined.
8.3.3 Conduct the CD test at the two points specified in
Section 6.1.2. Introduce to the CEMS the reference gases, optical
filters, or other suitable calibration reference media (these need
not be certified). Record the CEMS response and subtract this value
from the reference value.
8.4 Calibration Test Procedure
8.4.1 Calibration Test Period. Conduct the calibration test
according to the procedure given in Sections 8.4.2 through 8.4.7
while the affected facility is operating at more than 50 percent of
normal load or as specified in an applicable Subpart. The
calibration test may be conducted during the CD test period.
8.4.2 Reference Methods. Unless otherwise specified in an
applicable Subpart of the regulations, Method 3B, 4, and 5I, or
other approved alternatives, are the Reference Methods for diluent
(O2), moisture, and PM, respectively. Method 5 should be
used instead of Method 5I if PM emissions exceed 45 mg/dscm (0.02
gr/dscf).
8.4.3 Sampling Strategy for Reference Method tests. Conduct the
Reference Method tests in such a way that they will yield results
representative of the emissions from the source and can be
correlated to the CEMS data. Conduct the diluent (if applicable),
moisture, (if needed), and PM measurements simultaneously. In order
to correlate the CEMS and Reference Method data properly, make sure
the time from the CEMS data recorder and the time instrument used
for the Reference Method agree and note the beginning and end of
each Reference Method test period of each run (including the exact
time of day) on the CEMS chart recordings or other permanent record
of output. Make two sample traverses for a total of at least 60
minutes, sampling for an equal time at each traverse point (see
Section 8.1.3.2 for discussion of traverse points). The use of
paired Method 5I (or Method 5 as appropriate) trains (that is,
simultaneously traversing across two 90 deg.-opposed axes) is
recommended to improve and assure data quality.
Note: At times, CEMS calibration tests may be conducted during
new source performance standards, performance tests or other
compliance tests subject to the Clean Air Act or other statutes,
such as the Resource Conservation and Recovery Act. In these cases,
Reference Method results obtained during CEMS calibration test may
be used to determine compliance as long as the source and test
conditions are consistent with the applicable regulations.
8.4.4 Number of Runs in a Calibration Relation Test. Conduct a
minimum of 15 runs each consisting of simultaneous CEMS and
Reference Method measurements sets.
Note: More than 15 sets of CEMS and Reference Method measurement
sets may be performed. If this option is chosen, certain test
results may be rejected so long as the total number of test results
used to determine the calibration relation is greater than or equal
to 15. However, all data must be reported, including the rejected
data. The basis for rejecting data must be explicitly stated in: (1)
The Reference Method, this Performance Specification, or Procedure
2; or (2) the site's QA plan approved by the Administrator.
8.4.5 Structure of Tests. CEMS calibration tests shall be
carried out by making simultaneous CEMS and Reference Method
measurement sets at three (or more) different levels of PM mass
concentrations over the full range of operations experienced by the
facility, including emissions. Three (or more) sets of measurements
shall be obtained at each level. The different levels of PM mass
concentration should be obtained by varying process or PM control
device conditions as much as the process allows. If it is not
possible or practical to obtain PM measurement at the standard, it
is recommended that at least six measurement sets be performed at
the maximum PM emission level achievable to produce the most
accurate and representative results. This will help obtain the
smallest confidence and tolerance intervals at the maximum emission
level. Irrespective of the extent of the range, the three PM
concentration levels developed in the calibration tests must be
distributed over the complete operating range experienced by the
facility, and at least three of the minimum 15 measured data points
must lie within each of the following levels:
Level 1: 0 to 30% of the maximum PM concentration;
Level 2: 30 to 60% of the maximum PM concentration; and
Level 3: 60 to 100% of the maximum PM concentration.
8.4.6 Correlation of Reference Method and CEMS Data. If
necessary, adjust the CEMS outputs and Reference Method test data to
the same time. Determine the integrated (arithmetic average) CEMS
output over each Reference Method test period. Consider system
response time, if important, and confirm that the pair of results
are on a consistent moisture, temperature, and diluent concentration
basis. Adjust the Reference Method results to ensure they are on the
same basis as the CEMS measurements. Depending on the particular
CEMS measurement conditions, the CEMS and Method 5I (or Method 5
where applicable) correlations are based on either:
(a) Actual in-stack conditions and actual PM concentrations for
in-situ CEMS in mg/acm (i.e., account for the in-stack temperature,
pressure, and moisture),
(b) Actual CEMS measurement conditions for extractive CEMS in
mg/acm (i.e., account for the elevated temperature of the extracted
flue gas if heated), or
(c) Dry standard conditions and corresponding PM concentrations
in mg/dscm (i.e., do not correct the Reference Method results if the
CEMS outputs are on the same temperature and moisture basis as the
Reference Method). Calculate the appropriate PM concentrations as
specified by CEMS manufacturer using the applicable equations in
Section 12.0.
8.4.7 Calculate the correlation coefficient, confidence
interval, and tolerance interval for the complete set of CEMS/RM
data according to the procedures in Section 12.0.
8.5 Number of Calibration Tests
Because of the need to develop a calibration curve
representative of the facility/APC system, the following strategy
will ensure that the calibration curve facilities develop adequately
corresponds to measured PM concentrations:
Perform the initial calibration test and develop a correlation
within the time period
[[Page 67810]]
specified in the applicable regulation. For CEMS with measurement
technologies insensitive to changes in PM properties (e.g., Beta-
gage), this would be the only calibration test required.
For CEMS with measurement technologies sensitive to PM property
changes (e.g., Light-scattering), perform a second calibration
within the time period specified in the applicable regulation.
Compare the results of the two calibrations to determine what type
of mathematical model (e.g., arithmetic, log-normal, or quadratic)
best correlates with measured PM concentrations. The calibration for
the facility is a composite of both sets of calibration data.
Perform a third calibration test within the time period specified in
the applicable regulation. Compare the third calibration to the
first two. If this calibration relation confirms the findings of the
original two calibrations, then this is the last calibration test to
be performed. The final calibration relation for the facility is a
composite of all three sets of calibration data. If the third
calibration shows some fit other than the one originally determined
best correlates CEMS response to PM emission concentrations, then a
fourth calibration test must be performed within the time period
specified in the applicable regulation. This process of performing
additional calibration test continues until the facility can
determine what fit best correlates CEMS output to PM concentrations.
The final calibration is a composite of all calibration data
obtained.
8.6 Reporting. At a minimum, (check with the appropriate
regional office, State, or Local agency for additional requirements,
if any), summarize in tabular form the results of the CD tests and
the calibration tests, as appropriate. Include all data sheets,
calculations, charts (records of CEMS responses), process data
records including PM control equipment operating parameters, and
manufacturer's reference calibration media certifications necessary
to confirm that the performance of the CEMS met the performance
specifications.
9.0 Quality Control. [Reserved]
10.0 Calibration and Standardization. [Reserved]
11.0 Analytical Procedure.
Sample collection and analysis are concurrent for this
Performance Specification (see Section 8.0). Refer to the Reference
Method for specific analytical procedures.
12.0 Calculations and Data Analysis.
Summarize the results on a data sheet similar to that shown in
Table III (in Section 18.0).
12.1 Calibration and Zero Drift
12.1.1 Calibration Drift. Calculate the CD according to:
[GRAPHIC] [TIFF OMITTED] TP30DE97.029
where:
CD=the calibration drift of the CEMS in percent
RCEM=the CEMS response; and
RV=the reference value of the high level calibration
standard.
12.1.2 Calculate the ZD according to:
[GRAPHIC] [TIFF OMITTED] TP30DE97.030
where:
ZD=the zero drift of the CEMS in percent.
12.2 Calibration Evaluation
12.2.1 Treatment of Reference Method Data. All data from the
Reference Method and CEMS must be on the same basis. Correct the
Reference Method data for moisture, temperature, and pressure to the
same units as the CEMS using the equations below. Depending on the
particular CEMS measurement conditions, the CEMS and Reference
Method correlation is based on either:
(a) Actual in-stack conditions and actual PM concentrations for
in-situ monitors expressed in mg/acm (i.e., to account for the in-
stack temperature and moisture),
(b) Elevated CEMS temperature conditions and corresponding PM
concentrations in mg/acm at the analyzer (i.e., to account for the
increased temperature, relative to in-stack levels, in extracted
sample gas temperature), or
(c) Dry standard conditions and corresponding PM concentrations
in mg/dscm (i.e., to account for the moisture condensed in drying
the extracted sample before measuring gas volume, analogous to the
Reference Method).
Calculate the respective PM concentrations using the equations,
below.
Refer to the Results produced from the CFR Method 5, Section
6.9, Equation 5-6; Particulate Concentration Calculation in dry
standard units.
[GRAPHIC] [TIFF OMITTED] TP30DE97.031
where:
Cs=Concentration in mg/dscm
mn=Total amount of particulate matter collected, mg.
Vm(std)=Volume of gas sample as measured by dry gas
meter, corrected to standard condition, dscm.
12.2.2 Conversion of Reference Method Particulate
Concentrations to Other Units
where:
C=Concentration at actual stack conditions (mg/Acm),
Cs=Concentration at mg/dscm,
Cs@7%=Concentration at mg/dscm at 7% O2,
ts=Average stack gas temperature deg.F,
P=Absolute stack pressure (in Hg),
Bws=Water Vapor in the gas stream, proportion by
volume, and
O2=Stack Gas Oxygen Content.
(a) From dry standard concentration conditions to actual in
stack conditions (as applicable).
[GRAPHIC] [TIFF OMITTED] TP30DE97.032
(b) From dry standard concentration conditions to dry standard
concentration at 7 %O2.
[GRAPHIC] [TIFF OMITTED] TP30DE97.033
(c) From actual stack conditions to dry standard concentration.
[GRAPHIC] [TIFF OMITTED] TP30DE97.034
[[Page 67811]]
12.2.3 Linear Calibration. A linear calibration (i.e., linear
correlation) shall be calculated from the calibration data by
performing a linear least squares regression. The CEMS data appear
on the x axis, and the Reference Method data appear on the y axis.
Whether this fit is used depends on the outcome of the calculations
described in section 12.2.5 of this performance specification.
12.2.3.1 Linear Regression. The linear regression, which gives
the predicted mass emission,y, based on the CEMS response x, is
given by the equation:
[GRAPHIC] [TIFF OMITTED] TP30DE97.035
where:
[GRAPHIC] [TIFF OMITTED] TP30DE97.036
and
[GRAPHIC] [TIFF OMITTED] TP30DE97.037
The mean values of the x and y data sets are given by
[GRAPHIC] [TIFF OMITTED] TP30DE97.038
where xi and yi are the absolute values of the
individual measurements and n is the number of data points. The
values Sxx, Syy, and Sxy are given
by
[GRAPHIC] [TIFF OMITTED] TP30DE97.039
from which the scatter of y values about the regression line
(calibration) sL can be determined:
[GRAPHIC] [TIFF OMITTED] TP30DE97.040
12.2.3.2 Confidence Interval. The two-sided confidence
interval, yc,, for the predicted concentration y at point
x is given by the equation:
[GRAPHIC] [TIFF OMITTED] TP30DE97.041
12.2.3.3 Tolerance Interval. The two-sided tolerance interval
yt for the regression line is given by the equation:
[GRAPHIC] [TIFF OMITTED] TP30DE97.042
at the point x with kT=un' and f=n-2, where
[[Page 67812]]
[GRAPHIC] [TIFF OMITTED] TP30DE97.043
The tolerance factor unbullet for 75% of
the population is given in Table I as a function of n'. The factor
vf as a function of f is also given in Table I as well as
the t-factor at the 95% confidence level.
12.2.3.4 Correlation Coefficient. The correlation coefficient r
may be calculated from
[GRAPHIC] [TIFF OMITTED] TP30DE97.044
12.2.4 Quadratic Calibration Relation. In some cases, a
quadratic regression will provide a better fit to the calibration
data than a linear regression. The CEMS data appear on the x axis,
and the Reference Method data appear on the y axis. A test to
determine whether the quadratic regression gives a better fit to the
data than a linear regression must be performed. The relation with
the best fit must be used.
12.2.4.1 Quadratic Regression. A least-squares quadratic
regression gives the best fit coefficients b0,
b1, and b2 for the calibration relation:
[GRAPHIC] [TIFF OMITTED] TP30DE97.045
The coefficients b0, b1, and b2
are determined from the solution to the matrix equation Ab=B
where:
[GRAPHIC] [TIFF OMITTED] TP30DE97.046
The solutions to b0, b1, and b2
are:
[GRAPHIC] [TIFF OMITTED] TP30DE97.047
[GRAPHIC] [TIFF OMITTED] TP30DE97.048
[GRAPHIC] [TIFF OMITTED] TP30DE97.049
where:
[GRAPHIC] [TIFF OMITTED] TP30DE97.050
12.2.4.2 Confidence Interval. For any positive value of x, the
confidence interval is given by:
[GRAPHIC] [TIFF OMITTED] TP30DE97.051
where:
f = n-3,
tf is given in Table I,
[GRAPHIC] [TIFF OMITTED] TP30DE97.052
[GRAPHIC] [TIFF OMITTED] TP30DE97.053
[[Page 67813]]
The C coefficients are given below:
[GRAPHIC] [TIFF OMITTED] TP30DE97.054
where
[GRAPHIC] [TIFF OMITTED] TP30DE97.055
12.2.4.3 Tolerance Interval. For any positive value of x, the
tolerance interval is given by:
[GRAPHIC] [TIFF OMITTED] TP30DE97.056
where:
[GRAPHIC] [TIFF OMITTED] TP30DE97.057
[GRAPHIC] [TIFF OMITTED] TP30DE97.058
The vf and un' factors can also be found
in Table I.
12.2.5 Test to Determine Best Regression Fit. The test to
determine if the fit using a quadratic regression is better than the
fit using a linear regression is based on the values of s calculated
in the two formulations. If sL denotes the value of s
from the linear regression and sQ the value of s from the
quadratic regression, then the quadratic regression gives a better
fit at the 95% confidence level if the following relationship is
fulfilled:
[GRAPHIC] [TIFF OMITTED] TP30DE97.059
with f = n-3 and the value of Ff at the 95% confidence
level as a function of f taken from Table II below.
12.2.6 Alternative Mathematical Approaches to the Calibration.
Other non-linear relations may provide a better fit to the
calibration data than linear or quadratic relations because of the
monitor's response to some measurable property indicative of the PM
concentration. These approaches may serve as alternative approaches
for defining the mathematical relation between the CEMS response and
the Reference Method. The basis for developing such alternative
approaches must be explicitly included in the calibration relation
test report with supporting data demonstrating a better fit than
linear and quadratic relations and is subject to approval by the
Administrator.
13.0 Method Performance
13.1 Calibration Drift Performance Specification. The CEMS
internal calibration must not drift or deviate from the value of the
reference light, optical filter, Beta attenuation signal, or other
technology-suitable calibration reference media by more than 2
percent of the span value. If the CEMS includes diluent and/or
auxiliary monitors (for temperature, pressure, and/or moisture) that
are employed as a necessary part of this performance specification,
the CD must then be determined separately for each in terms of its
respective output (see the appropriate Performance Specification for
the diluent CEMS specification). None of the CDS may exceed the
specification.
13.2 Calibration Relation Performance Specifications. The CEMS
calibration relation must meet each of the following minimum
specifications for all three criteria.
Criterion A. The correlation coefficient shall be greater than
or equal to 0.90.
Criterion B. The confidence interval (95%) at the emission limit
shall be within 10% of the emission limit value specified in the
regulations.
Criterion C. The tolerance interval at the emission limit shall
have 95% confidence that 75% of all possible values are within 25%
of the emission limit value specified in the regulations.
13.3 PM Compliance Monitoring. The CEMS measurements shall be
reported to the Agency in the units of the standard expressed in the
regulations (i.e., mg/dscm,
14.0 Pollution Prevention. [Reserved]
15.0 Waste Management. [Reserved]
16.0 Alternative Procedures. [Reserved]
17.0 References
1. 40 CFR part 60, Appendix B, ``Performance Specification 2--
Specifications and Test Procedures for S02 and
NOx, Continuous Emission Monitoring Systems in Stationary
Sources.''
2. 40 CFR part 60, Appendix B, ``Performance Specification I--
Specification and Test Procedures for Opacity Continuous Emission
Monitoring Systems in Stationary Sources.
3. 40 CFR part 60, Appendix A, ``Method 1--Sample and Velocity
Traverses for Stationary Sources.''
4. 40 CFR part 266, Appendix IX, Section 2, ``Performance
Specifications for Continuous Emission Monitoring Systems.''
5. ISO 10155, ``Stationary Source Emissions--Automated
Monitoring of Mass Concentrations of Particles: Performance
Characteristics, Test Procedures, and Specifications,'' dated 1995,
American National Standards Institute, New York City.
6. G. Box, W. Hunter, J. Hunter, Statistics for Experimenters
(Wiley, New York, 1978).
7. M. Spiegel, Mathematical Handbook of Formulas and Tables
(McGraw-Hill, New York, 1968).
18.0 Reference Tables, Example Calculations, Diagrams, Flowcharts,
and Validation Data.
18.1 Reference Tables
Table I: Factors for Calculation of Confidence and Tolerance Intervals
------------------------------------------------------------------------
f tn-2 vn-2 n' un'(75)
------------------------------------------------------------------------
7................................... 2.365 1.7972 7 1.233
[[Page 67814]]
8................................... 2.306 1.7110 8 1.223
9................................... 2.262 1.6452 9 1.214
10.................................. 2.228 1.5931 10 1.208
11.................................. 2.201 1.5506 11 1.203
12.................................. 2.179 1.5153 12 1.199
13.................................. 2.160 1.4854 13 1.195
14.................................. 2.145 1.4597 14 1.192
15.................................. 2.131 1.4373 15 1.189
16.................................. 2.120 1.4176 16 1.187
17.................................. 2.110 1.4001 17 1.185
18.................................. 2.101 1.3845 18 1.183
19.................................. 2.093 1.3704 19 1.181
20.................................. 2.086 1.3576 20 1.179
21.................................. 2.080 1.3460 21 1.178
22.................................. 2.074 1.3353 22 1.177
23.................................. 2.069 1.3255 23 1.175
24.................................. 2.064 1.3165 24 1.174
25.................................. 2.060 1.3081 25 1.173
30.................................. 2.042 1.2737 30 1.170
35.................................. 2.030 1.2482 35 1.167
40.................................. 2.021 1.2284 40 1.165
45.................................. 2.014 1.2125 45 1.163
50.................................. 2.009 1.1993 50 1.162
------------------------------------------------------------------------
Table II: Values for Ff.
------------------------------------------------------------------------
f Ff f Ff
------------------------------------------------------------------------
1...................................... 161.4 16 4.49
2...................................... 18.51 17 4.45
3...................................... 10.13 18 4.41
4...................................... 7.71 19 4.38
5...................................... 6.61 20 4.35
6...................................... 5.99 22 4.30
7...................................... 5.59 24 4.26
8...................................... 5.32 26 4.23
9...................................... 5.12 28 4.20
10..................................... 4.96 30 4.17
11..................................... 4.84 40 4.08
12..................................... 4.75 50 4.03
13..................................... 4.67 60 4.00
14..................................... 4.60 80 3.96
15..................................... 4.54 100 3.94
------------------------------------------------------------------------
Table III: Field Test Data for Calibration
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
CEMS PM response M 5 Conc. (mg/
Run No. (mg/Acm) Date (arbitrary units) dscm) ave Ts ( deg.F) Bws Abs P (in Hg) O2 M5 Conc
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
1................................ .................... ................... ................... ................... ................... ................... ................... .........
2................................ .................... ................... ................... ................... ................... ................... ................... .........
3................................ .................... ................... ................... ................... ................... ................... ................... .........
4................................ .................... ................... ................... ................... ................... ................... ................... .........
5................................ .................... ................... ................... ................... ................... ................... ................... .........
6................................ .................... ................... ................... ................... ................... ................... ................... .........
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
18.2 Example Calculations
18.2.1 Method 5 concentrations conversions
Example (a): CEMS measurement conditions were made at actual
stack conditions, requiring that the Method 5 concentration must be
converted from dry standard to actual stack conditions.
where:
C= Concentration at actual stack conditions (mg/Acm): is unknown
Cs= 38.66 mg/dscm
ts= 291.7 deg.F
P = 30.13 in Hg
O2=Assumed to be 11.63% O2
Bws= .226
[[Page 67815]]
[GRAPHIC] [TIFF OMITTED] TP30DE97.060
C = 21.17 mg/Acm
Example (b) CEMS measurement conditions were made at the dry
standard condition. Convert the concentration to units of the
emission regulation (dry standard conditions at 7% O2).
where:
C [email protected]%= Concentration at standard conditions @ 7%
O2; is unknown
O2=Assumed to be 11.63% O2
[GRAPHIC] [TIFF OMITTED] TP30DE97.061
C s @7%=57.97 mg/dscm @ 7% O2
Example (c): The emission regulation (dry standard conditions at
7% O2) must be converted to actual stack conditions.
Using the Proposed Emission Limit: 50 mg/dscm @ 7% O2
where:
C s @7%= 50 mg/dscm @ 7% O2
ts = 291.4 deg.F, average temperature during initial
calibration
Bws = .201, average moisture during initial
calibration
P = 30.08, average absolute stack pressure during initial
calibration
[GRAPHIC] [TIFF OMITTED] TP30DE97.062
O2=Assumed to be 11.63% O2
C @7%= 28.22 mg/Acm 7% O2
[GRAPHIC] [TIFF OMITTED] TP30DE97.063
C=18.82 mg/Acm
Example (d) The following table is the data set of a
representative monitor and its initial calibration. These CEMS
measurement conditions are at actual stack conditions. X is the CEMS
arbitrary unit measurements and Y is the corresponding Method 5
concentration at actual stack conditions.
------------------------------------------------------------------------
Run x y
------------------------------------------------------------------------
1....................................................... 18.48 10.93
2....................................................... 21.85 11.19
3....................................................... 27.10 13.80
4....................................................... 31.54 16.70
5....................................................... 32.33 16.61
6....................................................... 8.35 2.64
7....................................................... 15.83 6.65
8....................................................... 11.95 6.01
9....................................................... 8.43 3.02
10...................................................... 9.59 4.15
11...................................................... 13.81 7.31
12...................................................... 21.48 11.93
13...................................................... 27.64 11.27
14...................................................... 7.08 3.11
15...................................................... 6.15 2.21
16...................................................... 8.92 5.50
17...................................................... 8.77 3.59
18...................................................... 17.10 6.96
19...................................................... 13.58 5.33
20...................................................... 14.14 6.70
21...................................................... 15.28 6.59
22...................................................... 13.92 7.00
23...................................................... 14.00 6.52
24...................................................... 15.09 4.76
25...................................................... 17.43 9.78
26...................................................... 21.63 10.22
27...................................................... 18.56 10.83
28...................................................... 48.53 18.81
29...................................................... 82.25 29.01
30...................................................... 83.04 28.88
31...................................................... 21.20 8.98
32...................................................... 60.00 22.38
33...................................................... 32.08 15.94
34...................................................... 43.05 20.19
35...................................................... 30.51 13.77
36...................................................... 12.45 3.84
------------------------------------------------------------------------
where:
Sxx = 12338.81
Syy = 1690.99
Sxy = 4410.24
x__ave = 23.699
y__ave = 10.365
SL = 1.836
[GRAPHIC] [TIFF OMITTED] TP30DE97.064
From equations 7,8, and 9, the line regression is
Correlation coefficient
From equation 16, the correlation coefficient is 0.966
Confidence interval
Using the Proposed Emission Limit: 50 mg/dscm @ 7% O2
converted to actual conditions in example (c) C=18.82 mg/Acm.
Calculate CEMS response (x) using line regression calculated above.
where:
tf = 2.032
[GRAPHIC] [TIFF OMITTED] TP30DE97.065
[[Page 67816]]
=18.82 mg/Acm1.0
Tolerance interval
where:
n' = 13
vf = 1.253
kT = 1.498
[GRAPHIC] [TIFF OMITTED] TP30DE97.066
18.3 Diagrams [Reserved]
YT=18.82 mg/Acm2.75
18.4 Flowcharts [Reserved]
18.5 Validation Data [Reserved]
Appendix III--Procedure 2
Procedure 2. Quality Assurance Requirements for Particulate Matter
Continuous Emission Monitoring Systems Used for Compliance
Determination
1. Applicability and Principal
1.1 Applicability. Procedure 2 is used to evaluate the
effectiveness of quality control (QC) and quality assurance (QA)
procedures and the quality of data produced by any particulate
matter (PM) continuous emission monitoring system (CEMS) that is
used for determining compliance with the emission standards on a
continuous basis as specified in the applicable regulation. The CEMS
may include diluent (e.g., O2) monitors and other
auxiliary monitoring equipment for measurement, determination, or
input of the gas temperature, pressure, moisture content, or sample
volume .
This procedure specifies the minimum QA requirements necessary
for the control and assessment of the quality of CEMS data submitted
to the Environmental Protection Agency (EPA). Source owners and
operators responsible for one or more CEMS's used for compliance
monitoring must meet these minimum requirements and are encouraged
to develop and implement a more extensive QA program or to continue
such programs where they already exist.
Data collected as a result of QA and QC measures required in
this procedure are to be submitted to the Agency. These data are to
be used by both the Agency and the CEMS operator in assessing the
effectiveness of the CEMS QC and QA procedures in the maintenance of
acceptable CEMS operation and valid emission data.
Appendix F, Procedure 2 applicability and the CEMS accuracy
assessments are determined by individual regulations.
1.2 Principal. The QA procedure consist of two distinct and
equally important functions. One function is the assessment of the
quality of the CEMS data by estimating accuracy. The other function
is the control and improvement of the quality of the CEMS data by
implementing QC policies and corrective actions. These two functions
form a control loop: When the assessment function indicates that the
data quality is inadequate, the control effort must be increased
until the data quality is acceptable. In order to provide uniformity
in the assessment and reporting of data quality, this procedure
explicitly specifies the assessment methods for response drift and
accuracy. The methods are based on procedures included in the
applicable performance specifications (PS's) in general, and are
specifically applicable to PS 11, in appendix B of 40 CFR part 60.
Procedure 2 also requires CEMS measurements of samples concurrent
with reference method (RM) measurements.
Because the control and corrective action function encompasses a
variety of policies, specifications, standards, and corrective
measures, this procedure treats QC requirements in general terms to
allow each source owner or operator to develop a QC system that is
most effective and efficient for the circumstances.
2. Definitions
2.1 Continuous Emissions Monitoring System means the total
equipment required for the determination of a particulate matter
mass concentration in units of the emission standard. The sample
interface, pollutant analyzer, diluent analyzer, other auxiliary
data monitor(s) and data recorder are the major subsystems of the
CEMS.
2.2 Calibration Drift (CD) means the difference in the CEMS
output readings from the established reference value after a stated
period of operation during which no unscheduled maintenance, repair,
or adjustment took place.
2.3 Calibration relation means the relationship between a CEMS
response and measured PM concentrations by the reference method
which is defined by a mathematical equation.
2.4 Calibration Standard means a reference material that
produces a known and unchanging response when presented to the
pollutant analyzer portion of the CEMS, and used to calibrate the
drift or response of the analyzer.
2.5 Flagged data means data marked by the CEMS indicating that
the response value is suspect or invalid.
2.6 Span Value means the upper limit of the CEMS measurement
range. The span value shall be documented by the CEMS manufacturer
with laboratory data.
2.7 Zero Drift (ZD) means the difference in the CEMS output
readings for zero input after a stated period of operation during
which no unscheduled maintenance, repair, or adjustment took place.
3. QC Requirements
Each source owner or operator must develop and implement a QC
program. As a minimum, each QC program must include written
procedures which should describe in detail, complete, step-by-step
procedures and operations for each of the following activities:
1. Internal-Calibration of CEMS relative to assessing CD.
2. CD determination and adjustment of CEMS.
3. Preventative maintenance of CEMS (including spare parts
inventory and sampling probe integrity).
4. Data recording, calculations, and reporting.
5. Accuracy audit procedures including sampling and analysis
methods, sampling strategy, and structuring test conditions over the
prescribed range of PM concentrations.
6. Program of corrective action for malfunctioning CEMS,
including flagged data periods.
As described in Section 5.2, whenever excessive inaccuracies
occur, the source owner or operator must revise the current written
procedures or modify or replace the CEMS to correct the deficiency
causing the excessive inaccuracies.
These written procedures must be kept on record and available
for inspection by the enforcement agency.
4. CD Assessment
4.1 CD Requirement. As described in 40 CFR 60.13(d), source
owners and operators of CEMS must check, record, and quantify the CD
at two concentration values at least daily (approximately 24 hours)
in accordance with the method prescribed by the manufacturer. The
CEMS calibration must, as minimum, be adjusted whenever the daily
zero drift or the daily span value exceeds two times the limits of
PS 11 in appendix B of this regulation.
4.2 Recording Requirement for Automatic CD Adjusting Monitors.
Monitors that automatically adjust the instrument responses to the
corrected calibration values (e.g., microprocessor control) must be
programmed to record the unadjusted concentration measured in the CD
prior to resetting the calibration, if performed, or record the
amount of adjustment.
4.3 Criteria for Excessive CD. If either the zero drift or the
daily span value exceeds twice the PS 11 drift specification for
five, consecutive, daily periods, the CEMS is out-of-control. If
either the zero drift or the daily span value exceeds four times the
PS 11 drift specification during any CD check, the CEMS is out-of-
control. If the CEMS is out-of-control, take necessary corrective
action. Following corrective action, repeat the CD checks.
4.3.1 Out-Of-Control Period Definition. The beginning of the
out-of-control period is the time corresponding to the completion of
the fifth, consecutive, daily CD check with a CD in excess of two
times the allowable limit, or the time corresponding to the
completion of the daily CD check that results in a CD in excess of
four times the allowable limit. The end of the out-of-control period
is the time corresponding to the completion of the CD check
following corrective action that results in the CD's at both the
zero or the daily span value points being within the corresponding
allowable CD limit (i.e., either two times or four times the
allowable limit in appendix B).
4.3.2 CEMS Data Status During Out-Of-Control Period. During the
period the CEMS is out-of-control, the CEMS data may not be used in
calculating emission compliance nor be counted towards meeting
minimum data availability as required and described in the
applicable subpart [e.g., 60.47a(f)].
4.4 Data Recording and Reporting. As required in 60.7(d) of
this regulation (40 CFR part 60), all measurements from the CEMS
must be retained on file by the source owner for at least 2 years.
However emission data obtained on each successive day while the CEMS
is out-of-control may not be included as part of the minimum daily
requirement of the applicable subpart [e.g., 60.47a(f)] nor be used
in the calculation of reported emissions for that period.
[[Page 67817]]
5. Data Accuracy Assessment
5.1 Auditing Requirements. Each CEMS must be audited at least
once each calender quarter. Successive quarterly audits shall occur
no closer than 2 months. The audits shall be conducted as follows:
5.1.1 Response Calibration Audit (RCA). The RCA must be
conducted at the frequency specified in the applicable regulation.
Conduct the RCA test according to the sampling strategy described in
Section 8.4.3 and according to the structure of test described in
Section 8.4.5, both of which are in PS 11 in appendix B, except that
the minimum of runs required shall be 12 in the RCA instead of 15 as
specified in PS 11. If it is not possible/practical to obtain three
measured data points in all three PM concentration ranges as
specified in Section 8.4.5 of PS 11, a minimum of three measured
data points in any of the two ranges specified in Section 8.4.5 is
acceptable, as long as at least all 12 data points lie within the
range of the calibration relation test.
5.1.2 Absolute Calibration Audit (ACA). If applicable, an ACA
shall be conducted each quarter except in the quarters when a RCA is
conducted.
To conduct an ACA: (1) Challenge the CEMS with an audit standard
or an equivalent audit reference to reproduce the monitor's
measurement at three points within the following ranges:
------------------------------------------------------------------------
Audit point Audit range
------------------------------------------------------------------------
1......................................... 0 to 20% of span value.
2......................................... 40 to 60% of span value and.
3......................................... 80 to 100% of span value.
------------------------------------------------------------------------
Challenge the CEMS three times at each audit point, and use the
average of the three responses in determining accuracy.
Use a separate audit standard or an equivalent audit reference
for audit points 1, 2, and 3.
The monitor should be challenged at each audit point for a
sufficient period of time to assure that the CEMS response has
stabilized.
(2) Operate each monitor in the mode, manner and range specified
by the manufacturer.
(3) Use only audit standards or equivalent audit references
specified and provided by the manufacturer. Store, maintain, and use
audit standards or equivalent audit references as specified by the
manufacturer. When National Institute of Standards and Testing
(NIST)-traceable audit standards become available for PM CEMS, their
use will be required.
The difference between the actual known value of the audit
standard or equivalent audit reference specified by the manufacturer
and the response of the monitor is used to assess the accuracy of
the CEMS.
5.1.3 Relative Accuracy Audit (RAA) [Reserved].
5.1.4 Sample Volume Audit (SVA). For applicable units with a
sampling system, an audit of the equipment to determine sample
volume (e.g., equipment measuring sampling flowrate for a known
time) must be performed once a year. The SVA procedure specified by
the manufacturer will be followed to assure that sample volume is
accurately measured across the normal range of sample volumes made
over the past year.
5.1.5 Other Alternative Audits. Other alternative audit
procedures may be used as approved by the Administrator for the
quarters when ACAs are to be conducted.
5.2 Excessive Audit Inaccuracy. If the audit results using the
RCA, ACA, RAA, or SVA, do not meet the criteria in Section 5.2.3,
the CEMS is out-of-control. If the CEMS is out-of-control, take
necessary corrective action to eliminate the problem. Following
corrective action, the source owner or operator must audit the CEMS
with a calibration relation test, ACA, RAA, or SVA to determine if
the CEMS is operating within the specifications. A calibration
relation test must always be used following an out-of-control period
resulting from a RCA. If audit results show the CEMS to be out-of-
control, the CEMS operator shall report both the audit showing the
CEMS to be out-of-control and the results of the audit following
corrective action showing the CEMS to be operating within
specifications.
5.2.1 Out-Of-Control Period Definitions. The beginning of the
out-of-control period is the time corresponding to the completion of
an unsuccessful RCA, ACA, RAA, or SVA. The end of the out-of-control
period is the time corresponding to the completion of the subsequent
successful calibration test or audit.
5.2.2 CEMS Data Status During Out-Of-Control Period. During the
period the monitor is out-of-control, the CEMS data may not be used
in calculating emission compliance nor be counted towards meeting
minimum data availability as required and described in the
applicable subpart.
5.2.3 Criteria for Excessive Audit Inaccuracy. Unless specified
otherwise in the applicable subpart, the criteria for excessive
inaccuracy are:
(1) For the RCA, at least 75% of a minimum number of 12 sets of
CEMS/reference method measurements from the test must fall within a
specified area on a graph developed by the calibration relation
regression line over the calibration range and the tolerance
interval set at +/-25% of the emission limit. The specified area on
a graph is (a) bounded by two lines parallel with the calibration
regression line, and offset at a distance +/-25% of the numerical
emission limit from the calibration regression line on the y-axis,
and (b) traversing across the calibration range bounded by the
lowest and the highest CEMS reading of the calibration test on the
x-axis.
(2) For the ACA, +/-15 percent of the average audit value or
7.5% of the applicable standard, whichever is greater.
(3) For the SVA, +/-5 percent of the average sample volume audit
value .
5.3 Criteria For Acceptable QC Procedure. Repeated excessive
inaccuracies (i.e., out-of-control conditions resulting from the
quarterly audits) indicates the QC procedures are inadequate or that
the CEMS is incapable of providing quality data. Therefore, whenever
excessive inaccuracies occur for two consecutive quarters, the
source owner or operator must revise the QC procedures (see Section
3) or modify or replace the CEMS.
6. Calculations for CEMS Data Accuracy and Acceptability
Determination
6.1 RCA Calculations and Determination of Acceptability.
6.1.1 RCA Calculations. Follow the equations described in
Section 12 of appendix B, PS 11 to calculate results from the RCA
tests. The reference method results from the RCA must be calculated
in units consistent with the CEMS measurement approach in use (e.g.,
mg/m3 or mg/dscm).
6.1.2 Acceptability Determination of RCA Data. Plot each of the
CEMS/reference method data from the RCA test on a figure based on
the calibration relation regression line to determine if the
appropriate criterion in Section 5.2.3 (1) is met.
6.2 ACA Accuracy Calculation. Use Equations 1 and 2 to
calculate results from the ACA tests.
[GRAPHIC] [TIFF OMITTED] TP30DE97.067
where:
A = Accuracy of the CEMS, percent.
RCEM = Average CEMS response during audit.
RV = Reference value of the audit calibration
standard or the equivalent audit.
[GRAPHIC] [TIFF OMITTED] TP30DE97.068
where:
A = Accuracy of the CEMS, percent.
RCEM = Average CEMS response.
RV = Reference value of the audit calibration
standard or the equivalent audit.
REM = the emission limit value.
6.3 SVA Accuracy Calculation. The appropriate SVA calculations
will be provided by the CEMS manufacturer.
6.4 Treatment of Flagged Data. All flagged CEMS data are
considered invalid; as such, these data may not be used in
determining compliance nor be counted towards meeting minimum data
availability as required and described in the applicable subpart.
6.5 Alternative Calibration Relation Approaches. Certain PM
CEMS have technologies established on principles measuring PM
concentration directly, whereas other technologies measure PM
properties indirectly indicative of PM concentration. It has been
shown empirically that a linear relationship can exist between these
properties and PM concentration over a narrow range of
concentrations, provided all variables remain essentially constant.
However, if all variables affecting this relationship do not remain
constant, then a linear relationship will probably not occur. Such
is the case expected for facilities with PM emissions over a wide
range of PM concentrations with certain process and air pollution
control configurations. Other non-linear relations may provide a
better fit to the calibration data than linear relations because the
monitor's response is based on some measurable, and changing,
property of the PM concentrations. These non-linear
[[Page 67818]]
approaches may serve as improved approaches for defining the
mathematical relation between the CEMS response and reference method
measured PM concentrations. The basis and advantage for developing
and implementing such alternative approaches for determining
compliance must be explicitly included in the calibration relation
test report with supporting data demonstrating a better fit than a
linear relation. Use of these alternative approaches is subject to
approval by the Administrator.
6.6 Example Accuracy Calculation. Example calculations and
illustration for the RCA are available in Citation 1. Example
calculations for the ACA are available in Citation 3 of Appendix F--
Procedure 1 and will be available in Citation 2.
7. Reporting Requirements
At the reporting interval specified in the applicable
regulation, report for each CEMS the accuracy results from Section 6
and the CD assessment results from Section 4. Report the drift and
accuracy information as a Data Assessment Report (DAR), and include
one copy of this DAR for each quarterly audit with the report of
emissions required under the applicable subparts of this part.
As a minimum, the DAR must contain the following information:
1. Source owner or operator name and address
2. Identification and location of monitors in the CEMS.
3. Manufacturer and model number of each monitor in the CEMS.
4. Assessment of CEMS data accuracy/acceptability and date of
assessment as determined by a RCA, ACA, RAA, or SVA described in
Section 5 including the acceptability determination for the RCA, the
A for the ACA or RAA or SVA, the RM results, the calibration audit
standards or equivalent audit references, the CEMS responses, and
the calculation results as defined in Section 6. If the accuracy
audit results show the CEMS to be out-of-control, the CEMS operator
shall report both the audit results showing the CEMS to be out-of-
control and the results of the audit following corrective action
showing the CEMS to be operating within specifications.
5. Summary of all corrective actions taken when CEMS was
determined out-of-control, as described in Sections 4 and 5.
An example of a DAR format will be shown later in Figure 1.
8. Bibliography
To Be Determined
Figure 1--Example Format For Data Assessment Report: To Be Determined
[FR Doc. 97-33740 Filed 12-29-97; 8:45 am]
BILLING CODE 6560-50-P
