[[pp. 52927-52976]] NESHAPS: Final Standards for Hazardous Air Pollutants for

Note: EPA no longer updates this information, but it may be useful as a reference or resource.

[Federal Register: September 30, 1999 (Volume 64, Number 189)]
[Rules and Regulations]
[Page 52927-52976]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr30se99-26]

[[pp. 52927-52976]] NESHAPS: Final Standards for Hazardous Air Pollutants for
Hazardous Waste Combustors

[[Continued from page 52926]]

[[Page 52927]]

used to increase method precision. This requirement applies whether you
use Method 5i to demonstration compliance with the emission standard or
to correlate a particulate matter CEMS. In addition, if you elect to
petition the Administrator for approval to use a particulate matter
CEMS and elect to use Method 5 to correlate the CEMS, you must also
obtain paired Method 5 data to improve method precision and, thus, the
correlation.
During our CEMS testing, we collected particulate matter data using
two simultaneously-conducted manual method sampling trains. We called
the results from these simultaneous runs ``paired data.'' We discussed
the use of paired trains in the December 1997 NODA as being optional
but requested comment on whether we should require paired trains, state
a strong preference for them, or be silent on the issue. Many
commenters believe paired trains should be used at all times so
precision can be documented. With these comments in mind, and
consistent with our continued focus on the collection of high quality
emission measurements, we include a requirement in Method 5i to obtain
paired data. Method 5i also includes a minimum acceptable relative
standard deviation between these data pairs. As discussed below, both
data in the pair are rejected if the data exceed the acceptable
relative standard deviation.
To improve the correlation between the manual method and a
particulate matter CEMS, we also recommend that sources electing to use
Method 5 also obtain paired Method 5 data. Again, data sets that exceed
an acceptable relative standard deviation, as discussed below, should
be rejected. This recommendation will be implemented during the
Administrator's review of your petition requesting use a particulate
matter CEMS. If you elect to correlate the CEMS using Method 5, you are
expected to include in your petition a statement that you will obtain
paired data and will conform with our recommended relative standard
deviation for the paired data.
iii. What Are the Procedures for Identifying Outliers? We have
established maximum relative standard deviation values for paired data
for both Method 5i and Method 5. If a data pair exceed the relative
standard deviation, the pair is identified as an outlier and is not
considered in the correlation of a particulate matter CEMS with the
reference method. In addition, Method 5i pairs that exceed the relative
standard deviation are considered outliers and cannot be used to
document compliance with the emission standard.
In the initial phase of our CEMS tests, we established a procedure
for eliminating imprecise data. This consisted of eliminating a set of
paired data if the data disagree by more than some previously
established amount. Two identical methods running at the same time
should yield the same result; if they do not, the precision of both
data is suspect. Commenters agree with the need to identify and
eliminate imprecise data to enhance method precision. This is an
especially important step when comparing manual particulate matter
measurements to particulate matter CEMS measurements. As a result, we
include criteria in Method 5i to ensure data precision.
When evaluating the particulate matter CEMS Demonstration Test
data, we screened the data to remove these precision outliers. Data
outliers at that time were defined as paired data points with a
relative standard deviation ²⁰⁹ of greater than 30 percent.
We developed this 30% criterion by analyzing historical Method 5 data.
Several commenters, including a particulate matter CEMS vendor with
extensive European experience with correlation programs, recommend that
we tighten the relative standard deviation criteria. We concur, because
Method 5i is more precise than Method 5 given the improvements
discussed above. Therefore, one would logically expect a reasonable
precision criterion such as the relative standard deviation derived
from Method 5i data to be less than a similarly reasonable one derived
from Method 5 data. We investigated the particulate matter CEMS
Demonstration Test data base as well other available Method 5i data
(such as the data from a test program recently conducted at another US
incinerator). We conclude that a 10% relative standard deviation for
particulate matter emissions greater than or equal to 10 mg/dscm,
increased linearly to 25% for concentrations down to 1 mg/dscm, is a
better representation of acceptable, precise Method 5i paired data
²¹⁰. Data obtained at concentrations lower than 1 mg/dscm
have no relative standard deviation limit.
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\209\ RSD, or ``relative standard deviation'', is a
dimensionless number greater than zero defined as the standard
deviation of the samples, divided by the mean of the samples. In the
special case where only 2 data represent the sample, the mathematics
of determining the relative standard deviation simplifies greatly to
|CA-CB |/(CA + CB),
where CA and CB are the concentration results
from the two trains that represent the pair.
\210\ See Chapter 11, Section 2 of the technical background
document for details on the statistical procedures used to derive
these benchmarks: USEPA, ``Final Technical Support Document for
Hazardous Waste Combustor MACT Standards, Volume IV: Compliance With
the Hazardous Waste Combustor Standards,'' July 1999.
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The relative standard deviation criterion for Method 5 data used
for particulate matter CEMS correlations continues to be 30%.
iv. Why Didn't EPA Issue Method 5i as Guidance Rather than
Promulgating It as a Method? Most commenters state that Method 5i
should be guidance rather than a published method and it should not be
a requirement for performing particulate matter CEMS correlation
testing or documenting compliance with the emission standard. In
particular, several commenters in the cement kiln industry express
concern over the limitations of Method 5i regarding the mass of
particulate it could collect. This section addresses these concerns.
We have promulgated Method 5i as a method because it provides
significant improvement in precision and accuracy of low level
particulate matter measurements relative to Method 5. Consequently,
although Method 5i is not a required method, we expect that permitting
officials will disapprove comprehensive performance test plans that
recommend using Method 5 for low level particulate levels. Further, we
expect that petitions to use a particulate matter CEMS that recommend
performance acceptance criteria (e.g., confidence level, tolerance
level, correlation coefficient) based on correlating the CEMS with
Method 5 measurements will be disapproved. This is because we expect
the CEMS to be able to achieve better acceptance criteria values using
Method 5i (because it is more accurate and precise than Method 5), and
expect better relative standard deviation between test pairs (resulting
in lower cost of correlation testing because fewer data would be
screened out as outliers).
Given that we expect and want widespread use of Method 5i, and to
ensure that its key provisions are followed, it is appropriate to
promulgate it as a method rather than guidance. If the procedure were
issued only as guidance, the source or stack tester could choose to
omit key provisions, thus negating the benefits of the method.
Relative to the direct reference in Method 5i that the method is
``most effective for total particulate matter catches of 50 mg or
less,'' this means the method is most effective at hazardous waste
combustors with particulate matter emissions below approximately 45 mg/
dscm (0.02 gr/dscf). This applicability statement is not
intended to be a bright line; total train catches exceeding 50 mg would
not invalidate

[[Page 52928]]

the method. Rather, we include this guidance to users of the method to
help them determine whether the method is applicable for their source.
Note that this statement is found in the applicability section of the
method, rather than the method description sections that follow. As
such, the reference is clearly an advisory statement, not a quality
assurance criterion. Total train catches above 50 mg are acceptable
with the method and the results from such trains can be used to
document compliance with the emission standard and for correlating
CEMS. But, users of Method 5i are advised that problems (such as
plugging of the filter) may arise when emissions are expected to exceed
45 mg/dscm. ²¹¹
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\211\ Stack testers have developed ways to deal with plugging of
a filter. Many stack testers simply remove the filter before it
plugs, install a new, clean filter, and continue the sampling
process where they left off with the old filter. The mass gain is
then the total mass accumulated on all filters during the run.
However, using multiple filters for a single run takes more time,
not only to install the new filter but also to condition and weigh
multiple filters for a single run. For Method 5i, it would also
involve more capital cost because the stack tester would need more
light-weight filter assemblies to perform the same number of runs.
For these reasons and even though the situation can be acceptably
managed, it is impractical to have the filter plug. This led to our
recommendation that Method 5i is best suited for particulate matter
(i.e., filter) loadings of at most 50 mg, or stack concentrations of
less than 45 mg/dscm (roughly 0.02 gr/dscf).
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v. What Additional Costs Are Associated with Method 5i? Commenters
raise several issues regarding the additional costs of performing
Method 5i testing relative to using Method 5. There is an added cost
for the purchase of new Method 5i filter housings. These new
lightweight holders are the key addition to the procedure needed to
improve precision and accuracy and represent a one-time expense that
emission testing firms or sources that perform testing in-house will
have to incur to perform Method 5i. We do not view this cost as
significant and conclude that the use of a light-weight filter housing
is a reasonable and appropriate feature of the method.
Other commenters suggest that the requirement for pesticide-grade
acetone in the version of Method 5i contained in the December 1997 NODA
unnecessarily raises the cost of performing the method. Instead, they
ask us to identify a performance level for the acetone instead of a
grade requirement because it would allow test crews to meet that
performance in the most economical manner. We agree that prescribing a
certain type of acetone may unnecessarily increase costs and removed
the requirement for pesticide-grade acetone. Accordingly, the same
purity requirements cited in Method 5 for acetone are maintained for
Method 5i. The prescreening of acetone purity in the laboratory prior
to field use, consistent with present Method 5 requirements, is also
maintained in Method 5i.
Commenters make similar cost-related comments relative to the
requirement for Teflon beakers. At the request of several
commenters, we have expanded the requirement for Teflon
beakers to allow the use of beakers made from other similar light-
weight materials. Because materials other than Teflon can
be used to fabricate light-weight breakers, changing the requirement
from a technology basis to a performance basis will reduce costs while
achieving the performance goals of the method.
There were no significant comments regarding the added cost of
paired-train testing.
vi. What Is the Practical Quantification Limit of the Method 5i
Filter Sample? We received several comments related to the minimum
detection limit of Method 5i, including: the minimum sample required,
guidance on how long to sample, what mass should ideally be collected
on any filter, and the practical quantification limit.
Commenters are concerned that while we address the maximum amount
of particulate matter the method could handle, we are silent on the
issue of what minimum sample is required. This is important because
analytical errors, such as weighing of the filters, tend to have the
same error value associated with it irrespective of the mass loading.
To address this concern, Method 5i provides guidance on determining the
minimum mass of the collected sample based on estimated particulate
matter concentrations.
Related to the particulate mass collection issue is the issue of
how long a user of Method 5i needs to sample in order to an adequate
amount of particulate on the filter. The amount of particulate matter
collected is directly related to time duration of the sampling period,
i.e., the longer one samples, the more particulate is collected and
vice-versa. Therefore, Method 5i provides guidance on selecting a
suitable sampling time based on the estimated concentration of the gas
stream.
Both these issues directly relate to how much particulate matter
should ideally be collected on any individual filter. Our experience
indicates a minimum target mass is 10 to 20 mg.
Finally, we conclude that the targeted practical quantification
limit for Method 5i is 3.0 mg of sample. Discussion of how this
quantification limit is determined is highly technical and beyond the
scope of this preamble. See the technical support document for more
details.²¹²
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\212\ See USEPA, ``Final Technical Support Document for
Hazardous Waste Combustor MACT Standards, Volume IV: Compliance With
the Hazardous Waste Combustor Standards,'' July 1999.
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vii. How Are Blanks Used with Method 5i? Several commenters
question the use of acetone blanks or made recommendations for
additional blanks. We clarify in this section the collection and use of
sample blank data.
We recognize that high blank results can adversely effect the
analytical results, especially at low particulate matter
concentrations. To avoid the effect high blank results can have on the
analytical results, today's Method 5i adopts a strategy similar to
several of the organic compound test procedures (such as Method 23 in
part 60 and Method 0010 in SW-846) that require collection of blanks
but do not permit correction to the analytical results. Collection and
analysis of blanks remains an important component in the sampling and
analysis process for documenting the quality of the data, however. If a
test run has high blank results, the data may be suspect. Permitting
officials will address this issue on a case-by-case basis.
The importance of minimizing contamination is stressed throughout
Method 5i for both sample handling and use of high purity sample media.
If proper handling procedures are observed, we expect that the blank
values will be less than the method detection limit or within the value
for constant weight determination (0.5 mg). Therefore, the allowance
for blank correction that is provided in Method 5 is not permitted in
Method 5i. The method also recommends several additional types of
blanks to provide further documentation of the integrity and purity of
the acetone throughout the duration of the field sampling program.
b. What Is the Status of Particulate Matter CEMS Performance
Specification 11 and Quality Assurance/Quality Control Procedure 2? We
are not finalizing proposed Performance Specification 11 and Quality
Assurance/Quality Control Procedure 2 because the final rule does not
require the use of particulate matter CEMS. We considered stakeholder
comments on these documents, however, and have incorporated many
comments into the current drafts. We plan to publish these documents
when we address the particulate matter CEMS requirement. In the
interim, we will make them available as guidance to sources that are

[[Page 52929]]

considering the option of using a particulate matter CEMS to document
compliance.
c. How Have We Resolved Other Particulate Matter CEMS Issues? In
this section we discuss two additional issues: (1) Why didn't we
require continuous opacity monitors for compliance with the particulate
matter standard for incinerators and lightweight aggregate kilns; and
(2) can high correlation emissions testing runs exceed the particulate
matter standard?
i. Why Didn't We Require Continuous Opacity Monitors for Compliance
Assurance for Incinerators and Lightweight Aggregate Kilns? As
discussed elsewhere in today's notice, we require cement kilns to use
continuous opacity monitors (COMS) to comply with a 20 percent opacity
standard to ensure compliance with the particulate matter emission
standard. This is the opacity component of the New Source Performance
Standard for particulate matter for Portland cement plants. See
Sec. 60.62. Because we are adopting the mass-based portion of the New
Source Performance Standard for particulate matter as the MACT standard
(i.e., 0.15 kg/Mg dry feed), the opacity component of the New Source
Performance Standard is useful for compliance assurance.
We do not require that incinerators and lightweight aggregate kilns
use opacity monitors for compliance assurance because we are not able
to identify an opacity level that is achievable by sources using MACT
control and that would ensure compliance with the particulate matter
standards for these source categories. This is the same issue discussed
above in the context of particulate matter CEMS and is the primary
reason that we are not requiring use of these CEMS at this time.
Although we are requiring that cement kilns use COMS for compliance
assurance, these monitors cannot provide the same level of compliance
assurance as particulate matter CEMS. Opacity monitors measure a
characteristic of particulate matter (i.e., opacity) and cannot
correlate with the manual stack method as well as a particulate matter
CEMS. COMS are particularly problematic for sources with small stack
diameters (e.g., incinerators) and low emissions because both of these
factors contribute to very low opacity readings which results in high
measurement error as a percentage of the opacity value. Thus, we are
obtaining additional data to support rulemaking in the near future to
require use of particulate matter CEMS for compliance assurance.
Approximately 80 percent of hazardous waste burning cement kilns
are not currently subject to the New Source Performance Standard and
many of these sources may not be equipped with COMS that meet
Performance Specification 1 in appendix B, part 60. Thus, many
hazardous waste burning cement kilns will be required to install COMS,
even though we intend to require use of particulate matter CEMS in the
near future. We do not believe that this requirement will be overly
burdensome, however, because sources may request approval to install
particulate matter CEMS rather than COMS. See Sec. 63.8(f). Our testing
of particulate matter CEMS at a cement kiln will be completed well
before sources need to make decisions on how best to comply with the
COMS requirement of the rule. We will develop regulations and guidance
on performance specifications and correlation criteria for particulate
matter CEMS as a result of that testing, and sources can use that
guidance to request approval to use a particulate matter CEMS in lieu
of a COMS. We expect that most sources will elect to use this approach
to minimize compliance costs over the long term.
ii. Can High Correlation Runs Exceed the Particulate Matter
Standard? The final rule states that the particulate matter and opacity
standards of parts 60, 61, 63, 264, 265, and 266 (i.e., all applicable
parts of Title 40) do not apply during particulate matter CEMS
correlation testing, provided that you comply with certain provisions
discussed below that ensure that the provision is not abused. This
provision, as the rest of the rule, is effective immediately. Thus, you
need not wait for the compliance date to take advantage of this
particulate matter CEMS correlation test provision.
We include this provision in the rule because many commenters
question whether high correlation test runs that exceed the particulate
matter emission standard constitute noncompliance with the standard. We
have responded to this concern previously by stating that a single
manual method test run that exceeds the standard does not constitute
noncompliance with the standard because compliance is based on the
average of a minimum of three runs.²¹³ We now acknowledge,
however, that during high run correlation testing a source may need to
exceed the emission standard even after averaging emissions across
runs. Similarly, a source may need to exceed a particulate matter
operating parameter limit. Given the benefits of compliance assurance
using a CEMS, we agree with commenters that short-term excursions of
the particulate matter standard or operating parameter limits for the
purpose of CEMS correlation testing is warranted. The benefits that a
CEMS provides for compliance assurance outweighs the short-term
emissions exceedances that may occur during high end emissions
correlation testing. Consequently, we have included a conditional
waiver of the applicability of all Federal particulate matter and
opacity standards (and associated operating parameter limits).
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\213\ One exception is the destruction and removal efficiency
standard, for which compliance is based on a single test run and not
the average of three runs.
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The waiver of applicability of the particulate matter and opacity
emission standards and associated operating parameter limits is
conditioned on the following requirements to ensure that the waiver is
not abused. Based on information from commenters and expertise gained
during our testing, the rule requires that you develop and submit to
permitting officials a particulate matter CEMS correlation test plan
along with a statement of when and how any excess emissions will occur
during the correlation tests (i.e., how you will modify operating
conditions to ensure a wide range of particulate emissions, and thus a
valid correlation test). If the permitting officials fail to respond to
the test plan in 30 days, you can proceed with the tests as described
in the test plan. If the permitting officials comment on the plan, you
must address those comments and resubmit the plan for approval.
In addition, runs that exceed any particulate matter or opacity
emission standard or operating parameter limit are limited to no more
than a total of 96 hours per correlation test (i.e., including all runs
of all test conditions). We determined that the 96 hour total duration
for exceedances for a correlation test is reasonable because it is
comprised of one day to increase emissions to the desired level and
reach system equilibrium, two days of testing ²¹⁴ at the
equilibrium condition followed by a return to normal equipment settings
indicative of compliance with emissions standards and operating
parameter limits, and one

[[Page 52930]]

day to reach equilibrium at normal conditions. Finally, to ensure these
periods of high emissions are due to the bona fide need described here,
a manual method test crew must be on-site and making measurements (or
in the event some unforseen problem develops, prepared to make
measurements) at least 24 hours after you make equipment or workplace
modifications to increase particulate matter emissions to levels of the
high correlation runs.
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\214\ The two days assumes sources will conduct a total of 18
runs, 6 runs in each of the low, medium, and high particulate matter
emission ranges. To approve use of a particulate matter CEMS, we
will likely require that a minimum of 15 runs comprise a correlation
test. If this is the case, some runs will likely be eliminated
because they fail method or source-specific quality assurance/
quality control procedures.
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3. What Is the Status of Total Mercury CEMS?
We are not requiring use of total mercury CEMS in this rulemaking
because data in hand do not adequately demonstrate nationally that
these CEMS are reliable compliance assurance tools at all types of
facilities. Nonetheless, we are committed to the development of CEMS
that measure total mercury emissions and are continuing to pursue the
development of these CEMS in our research efforts.
In the April 1996 NPRM, we proposed that total mercury CEMS be used
for compliance with the mercury standards. We also said if you elect to
use a multimetals CEMS that passed proposed acceptability criteria, you
could use that CEMS instead of a total mercury CEMS to document
compliance with the mercury standard. Finally, we indicated that if
neither mercury nor multimetal CEMS were required in the final rule
(i.e., because they have not been adequately demonstrated), compliance
assurance would be based on specified operating parameter limits.
In the March 1997 NODA, we elicited comment on early aspects of our
approach to demonstrate total mercury CEMS. And, in the December 1997
NODA, we presented a summary of the demonstration test results and our
preliminary conclusion that we were unable to adequately demonstrate
total mercury CEMS at a cement kiln, a site judged to be a reasonable
worst-case for performance of the total mercury CEMS. As new data are
not available, we continue to adhere to this conclusion, and comments
received in response to the December 1997 NODA concur with this
conclusion. Therefore, we are not requiring total mercury CEMS in this
rulemaking.
Nonetheless, the current lack of data to demonstrate total mercury
CEMS at a cement kiln or otherwise on a generic bases (i.e., for all
sources within a category) does not mean that the technology, as
currently developed, cannot be shown to work at particular sources.
Consequently, the final rule provides you the option of using total
mercury CEMS in lieu of complying with the operating parameter limits
of Sec. 63.1209(l). As for particulate matter and other CEMS, the rule
allows you to petition the Administrator (i.e., permitting officials)
under Sec. 63.8(f) to use a total mercury CEMS based on documentation
that it can meet acceptable performance specifications, correlation
acceptance criteria (i.e., correlation coefficient, tolerance level,
and confidence level). Although we are not promulgating the proposed
performance specification for total mercury CEMS (Performance
Specification 12) given that we were not able to document that a
mercury CEMS can meet the specification in a (worst-case) cement kiln
application, the proposed specification may be useful to you as a point
of departure for a performance specification that you may recommend is
achievable and reasonable.
4. What Is the Status of the Proposed Performance Specifications for
Multimetal, Hydrochloric Acid, and Chlorine Gas CEMS?
We are not promulgating proposed Performance Specifications 10, 13,
and 14 for multimetal, hydrochloric acid, and chlorine gas CEMS because
we have not determined that the CEMS can achieve the specifications.
In the April 1996 NPRM, we proposed performance specifications for
multimetal, hydrochloric acid, and chlorine gas CEMS to allow sources
to use these CEMS for compliance with the metals and hydrochloric acid/
chlorine gas standards. Given that we have not demonstrated that these
CEMS can meet their performance specifications and our experience with
a mercury CEMS where we were not able to demonstrate that the mercury
CEMS could meet our proposed performance specification, we are not
certain that these CEMS can meet the proposed performance
specifications. Accordingly, it would be inappropriate to promulgate
them.
As discussed previously, we encourage sources to investigate the
use of CEMS and to petition permitting officials under Sec. 63.8(f) to
obtain approval to use them. The proposed performance specifications
may be useful to you as a point of departure in your efforts to
document performance specifications that are achievable and that ensure
reasonable correlation with reference manual methods.
5. How Have We Addressed Other Issues: Continuous Samplers as CEMS,
Averaging Periods for CEMS, and Incentives for Using CEMS?
a. Are Continuous Samplers a CEMS? Several commenters, mostly
owner/operators of on-site incinerators, suggest that we should adjust
certain CEMS criteria (e.g., averaging period, response time) to allow
use of a continuous sampler known as the 3M Method. The 3M Method is a
continuous metals sampling system. It automatically extracts stack gas
and accumulates a sample on a filter medium over any desired period--24
hours, days, or weeks. The sample is manually extracted, analyzed, and
reported. Various incinerator operators are using or have expressed an
interest in using this type of approach to demonstrate compliance with
current RCRA metals emission limits. Many commenters contend that the
3M Method is a CEMS and that we developed our performance
specifications for CEMS to exclude techniques like the 3M Method.
After careful analysis, we conclude that the 3M Method is not a
CEMS. It does not meet our long-standing definition of a CEMS in parts
60 or 63. Specifically, it is not a fully automated piece(s) of
equipment used to extract a sample, condition and analyze the sample,
and report the results of the analysis in the units of the standard.
Also, the 3M Method is unable to ``complete a minimum of one cycle of
operation (sampling, analyzing, and data recording) for each successive
15-minute period'' as required by Sec. 63.8(c)(4)(ii). As a result,
making the subtle changes (e.g., to the averaging period, response
time) to our multimetal CEMS performance specification that commenters
recommend would not alter the fact that the device does not
automatically analyze the sample on the frequency required for a CEMS.
A continuous sampler (coupled with periodic analysis of the sample)
is inferior to a CEMS for two reasons. First, if the sampling period is
longer than the time it takes to perform three manual performance
tests, compliance with the standard cannot be assured. Approaches like
the 3M Method tend to have reporting periods on the order of days,
weeks, or even a month. The reporting period is comprised of the time
required to accumulate the sample and the additional time to analyze
the sample and report results. Because the stringency of a standard is
a function of both the numerical value of the standard and the
averaging period (e.g., at a given numerical limit, the longer the
averaging period the less stringent the standard), a compliance
approach having a sampling period greater than the 12 hours we estimate
it may take to conduct three manual method stack test runs using Method
29 cannot ensure

[[Page 52931]]

compliance with the standard.²¹⁵ If the sampling period were
greater than the time required to conduct three test runs, the
numerical value of the standard would have to be reduced to ensure an
equally stringent standard. Unfortunately, we do not know how to derive
alternative emission limits as a function of the averaging period that
would be equivalent to the emission standard. We raised this issue at
proposal, and commenters did not offer a solution.
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\215\ A technical support document for the February 1991
municipal waste combustor rule contains a good description of how
not only the numerical limit, but the averaging period as well,
determines the overall stringency of the standard. See Appendices A
and B found in ``Municipal Waste Combustion: Background Information
for Promulgated Standards and Guidelines--Summary of Public Comments
and Responses Appendices A to C'', EPA-450/3-91-004, December 1990.
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Second, the results from a continuous sampler are reported after
the fact, resulting in higher excess emissions than with a CEMS.
Depending on the sample analysis frequency, it could take days or weeks
to determine that an exceedance has occurred and that corrective
measures need to be taken. A CEMS can provide near real-time
information on emissions such that exceedances can be avoided or
minimized.
Absent the generic availability of multimetal CEMS, continuous
samplers such as the 3M Method may nonetheless be a valuable compliance
tool. We have acknowledged that relying on operating parameter limits
may be an imperfect approach for compliance assurance. Sampling and
analysis of feedstreams to determine metals feedrates can be
problematic given the complexities of some waste matrices. In addition,
the operating parameters for the particulate matter control device for
which limits must be established may not always correlate well with the
device's control efficiency for metals and thus metals emissions.
Because of these concerns, we encourage sources to investigate the
feasibility of multimetal CEMS. But, absent a CEMS, a continuous
sampler may provide an attractive alternative or complement to some of
the operating parameter limits under Secs. 63.1209 (l) and (n). You may
petition permitting officials under Sec. 63.8(f) to use the 3M Method
(or other sampler) as an alternative method of compliance with the
emissions standards. Permitting officials will balance the benefits of
a continuous sampler with the benefits of the operating parameter
limits on a case-by-case basis.
b. What Are the Averaging Periods for CEMS and How Are They
Implemented? We discuss the following issues in this section: (1)
Duration of the averaging period; (2) frequency of updating the
averaging period; and (3) how averaging periods are calculated
initially and under intermittent operations.
i. What Is the Duration of the Averaging Period? We conclude that a
six-hour averaging period is most appropriate for particulate matter
CEMS, and a 12-hour averaging period is most appropriate for total
mercury, multi metals, hydrogen chloride, and chlorine gas CEMS.
We proposed that the averaging period for CEMS (i.e., other than
carbon monoxide, hydrocarbon, and oxygen) be equivalent to the time
required to conduct three runs of the comprehensive performance test
using manual stack methods. As discussed above and at proposal, we
proposed this approach because, to ensure compliance with the standard,
the CEMS averaging period must be the same as the time required to
conduct the performance test.²¹⁶
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\216\ Actually, the CEMS averaging period can be no longer than
the time required to conduct three runs of the performance test to
ensure compliance with the standard. Although compliance with the
standard would be ensured if the CEMS averaging period were less
than the time required to conduct the performance test, this
approach would be overly stringent because it would ensure
compliance with an emission level lower than the standard.
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Commenters suggest two general approaches to establish averaging
periods for CEMS: technology-based and risk-based. Commenters
supporting a technology-based approach favor our proposed approach and
rationale where the time duration of three emissions tests would be the
averaging period for CEMS. Commenters favoring a risk-based approach
state that the averaging period should be years rather than hours
because the risk posed by emissions at levels of the standard were not
found to be substantial, assuming years of exposure. We disagree with
this rationale. CEMS are an option (that sources may request under
Sec. 63.8(f)) to document compliance with the emission standard. As
discussed above, if the averaging period for CEMS were longer than the
duration of the comprehensive performance test, we could not ensure
that a source maintains compliance with the standards.
Establishing an averaging period based on the time to conduct three
manual method stack test runs is somewhat subjective. There is no fixed
sampling time for manual methods--sampling periods vary depending on
the amount of time required to ``catch'' enough sample. Thus, we have
some discretion in selecting an averaging period using this approach.
Commenters generally favor longer averaging periods as an incentive for
using CEMS (i.e., because a limit is less stringent if compliance is
based on a long versus short averaging period). We agree that choosing
a longer averaging period would provide an incentive for the use of
CEMS, but conclude that the selected averaging period must be within
the range (i.e., high end) of times required to perform the three stack
test runs.
We derive the averaging period for particulate matter CEMS as
follows. Most particulate matter manual method tests are one hour in
duration, but a few stack sampling companies sample for longer periods,
up to two hours. Therefore, we use the high end of the range of values,
2 hours, as the basis for calculating the averaging period. We
recommend a six-hour rolling average considering that it may require 2
hours to conduct each of three stack tests.
For mercury, multi-metals, hydrochloric acid, and chlorine gas
CEMS, we recommend a 12-hour rolling averaging. The data base we used
to determine the standards shows that the sampling periods for manual
method tests for these standards ranged from one to four hours.
Choosing the high end of the range of values, 4 hours, as the basis for
calculating the averaging period, we conclude that a 12-hour rolling
average would be appropriate.
ii. How Frequently Is the Rolling Average Updated? We conclude that
the rolling average for particulate matter, total mercury, and
multimetal CEMS should be updated hourly, while the rolling average for
hydrochloric acid and chlorine gas CEMS should be updated each minute.
We proposed that all rolling averages would be updated every minute
and would be based on the average of the one-minute block average CEMS
observations that occurred over the averaging period. This proposed
one-minute update is the same that is used for carbon monoxide and
total hydrocarbon CEMS under the RCRA BIF regulations. (We are
retaining that update frequency in the final rule for those monitors,
and recommend it for hydrochloric acid and chlorine gas CEMS.)
Commenters favor selecting the frequency of updating the rolling
average taking into account the variability of the CEMS and limitations
concerning how the correlation data are collected. We agree with this
approach, as discussed below.
1. Particulate Matter CEMS. Commenters said that particulate matter
CEMS correlation tests are approximately one hour in duration and, if
the rolling average were updated

[[Page 52932]]

each minute, the CEMS would observe more variability in emissions
within this one hour than the manual method (which is an average of
those emissions during the hour). For this reason, we conclude it is
reasonable that particulate matter CEMS data be recorded as a block-
hour and that the rolling average be updated every hour as the average
of the previous six block-hours. Updating the particulate matter CEMS
every hour also means the number of compliance opportunities is the
same irrespective of whether a light-scattering or beta-gage
particulate matter CEMS is used (i.e., because beta-gage CEMS make
observations periodically while light-scattering CEMS make observations
continuously).
Furthermore, to ensure consistency with existing air rules
governing CEMS other than opacity, a valid hour should be comprised of
four or more equally spaced measurements during the hour. See
Sec. 60.13(h). This means that batch systems, such as beta gages, must
complete one cycle of operation every 15 minutes, or more frequently if
possible. See Sec. 63.8(c)(4)(ii). CEMS that produce a continuous
stream of data, such as light-scattering CEMS, will produce data
throughout the hour.
You may not be able to have four valid 15-minute measurement in an
hour, however, to calculate an hourly block-average. Examples include
when the source shuts down or the CEMS produces flagged (i.e.,
problematic) data. In addressing this issue, we balanced the need for
the average of the measurements taken during the hour to be
representative of emissions during the hour with the need to
accommodate problems with data availability that will develop. We
conclude that a particulate matter CEMS needs to sample stack gas and
produce a valid result from this sample for most of the hour. This
means that the CEMS needs to be observing stack gas at least half (30
minutes, or two 15-minute cycles of operation) of the block-hour.
Emissions from less than one hour might be unrepresentative of
emissions during the hour, and on balance we conclude that this
approach is reasonable. If a particulate matter CEMS does not sample
stack gas and produce a valid result from that sample for at least 30
minutes of a given hour, the hour is not a valid block-hour. In
documenting compliance with the data availability recommendation in the
draft performance specification, invalid block-hours due to
unavailability of the CEMS that occur when the source is in operation
count against data availability. If the hour is not valid because the
source was not operating for more than 30 minutes of the hour, however,
the invalid block-hour does not count against the data availability
recommendation.²¹⁷
---------------------------------------------------------------------------

\217\ Data availability is defined as the fraction, expressed as
a percentage, of the number of block-hours the CEMS is operational
and obtaining valid data during facility operations, divided by the
number of block-hours the facility was operating.
---------------------------------------------------------------------------

2. Total Mercury and Multimetal CEMS. As discussed for particulate
matter CEMS, we also expect manual methods will be required to
correlate total mercury and multimetal CEMS prior to using them for
compliance. For the reasons discussed above in the context of
particulate matter CEMS, we therefore recommend the observations from
these CEMS be recorded as block-hour averages and that the 12-hour
rolling average be updated every hour based on the average of the
previous 12 block-hour averages.
3. Hydrochloric Acid and Chlorine Gas CEMS. Unlike the particulate
matter, total mercury, and multimetal CEMS, hydrochloric acid and
chlorine gas CEMS are likely to be calibrated using Protocol 1 gas
bottles rather than correlated to manual method stack test results.
Therefore, the variability of observations measured by the CEMS over
some averaging period versus the duration of a stack test is not an
issue. We conclude that it is appropriate to update the 12-hour rolling
average for these CEMS every minute, as required for carbon monoxide
and hydrocarbons CEMS.
iii. How Are Averaging Periods Calculated Initially and under
Intermittent Operations?
1. Practical Effective Date of Rolling Averages for CEMS. As
discussed in Part Five, Sections VII.B.4 above in the context of
continuous monitoring systems in general, CEMS recordings will not
become effective for compliance monitoring on the compliance date until
you have recorded enough observations to calculate the rolling average
applicable to the CEMS. For example, the six hourly rolling average for
particulate matter CEMS does not become effective until you have
recorded six block-hours of observations on the compliance date. Given
that compliance with the standards begins nominally at 12:01 am on the
compliance date, the six hour rolling average for particulate matter
CEMS does not become effective as a practical matter until 6:01 am on
the compliance date. Similarly, the 12-hour rolling average for a
multimetal CEMS does not become effective until you have recorded 12
block-hours of observations after the compliance date. Thus, the 12-
hour rolling average for multimetals CEMS becomes effective as a
practical matter at 12:01 p.m. on the compliance date.
We adopt this approach simply because a rolling average does not
exist until enough observations have been recorded to calculate the
rolling average.
2. How Rolling Averages Are Calculated Upon Intermittent
Operations. We have determined that you are to ignore periods of time
when CEMS observations are not recorded for any reason (e.g., source
shutdown) when calculating rolling averages. For example, consider how
the six hour rolling average for a particulate matter CEMS would be
calculated if a source shuts down for yearly maintenance for a three
week period. The first one-hour block average value recorded when the
source renews operations is added to the last 5 one-hour block averages
recorded before the source shut down for maintenance to calculate the
six hour rolling average.
We adopt this approach for all continuous monitoring systems,
including CEMS, because it is simple and reasonable. See discussion in
Part Five, Section B.4 above.
c. What Are the Incentives for Using CEMS as Alternative
Monitoring? We strongly support the use of CEMS for compliance with
standards, even though we are not requiring their use in today's rule
(except for carbon monoxide, hydrocarbon, and oxygen CEMS) for the
reasons discussed above. We endorse the principle that, as technology
advances, current rules should not act as an obstacle to adopting new
CEMS technologies for compliance. For instance, today's rule does not
require total mercury CEMS because implementation and demonstration
obstacles observed during our tests under what we consider worst-case
conditions (i.e., a cement kiln) could not be resolved in sufficient
time to require total mercury CEMS at all hazardous waste combustors.
However, we fully expect total mercury CEMS will improve to the point
that the technical issues encountered in our tests can be resolved. At
that point, we do not want the compliance regime of today's rule--
comprised of emissions testing and limits on operating parameters--to
be so rigid as to preclude the use of CEMS. Commenters are generally
supportive of this concept, but note that facilities would be reluctant
to adopt new technologies without adequate incentives. This section
describes potential incentives: emissions testing would not be
required; limits on operating parameters would not apply while the CEMS
is in service; and the feedstream analysis requirements for the

[[Page 52933]]

parameters measured by the CEMS (i.e., metals or chlorine) would not
apply.
i. What Incentives Do Commenters Suggest? Several commenters
suggest that we provide various incentives to encourage development and
implementation of new and emerging CEMS. Comments by the Coalition for
Responsible Waste Incineration (CRWI) include a variety of actions to
encourage voluntary installation of CEMS,²¹⁸ including:
Reduce testing for any parameter measured by a CEMS to the correlation
and maintenance of that CEMS; waive operating parameter limits that are
linked to the pollutant measured by the CEMS; minimize regulatory
oversight on waste analysis if compliance is consistently demonstrated
by a CEMS; increase the emission limit for a source using a CEMS to
account for the uncertainty of CEMS observations; allow a phase-in
period when a source can evaluate CEMS performance and develop
maintenance practices and the CEMS would not be used for compliance;
allow a phase-in period to establish a reasonable availability
requirement for that CEMS at a particular location; and allow sources
to evaluate CEMS on a trial basis to determine if these instruments are
appropriate for their operations with no penalties if the units do not
work or have excessive downtime. Many of CRWI's suggestions have merit,
as discussed below.
---------------------------------------------------------------------------

\218\ By ``optional use of CEMS'', we mean using CEM not
required by this rule, i.e., other than those for carbon monoxide,
oxygen, and hydrocarbon.
---------------------------------------------------------------------------

ii. How Do We Respond to Commenter's Recommended Incentives?
1. Waiver of Emissions Testing and Operating Parameter Limits.
CRWI's first two suggestions (reduced testing and waiver of operating
parameter limits) are closely linked. The purpose of conducting a
comprehensive performance test is to document compliance with emission
standard initially (and periodically thereafter) and establish limits
on specified operating parameters to ensure that compliance is
maintained. Because a CEMS ensures compliance continuously, it serves
the purpose of both the performance test and compliance with operating
parameter limits. Accordingly, we agree with CRWI that both emissions
testing and operating parameter limits for the pollutant in question
would not apply to sources using a CEMS.
There is one key caveat to this position, however. Because 100%
availability of any CEMS is unrealistic, we require a means of assuring
compliance with the emission standards during periods when the CEMS is
not available. To meet that need, you may elect to install redundant
CEMS or assure continuous compliance by monitoring and recording
traditional operating parameter limits during periods when the CEMS is
not available. Most likely, you will elect to use operating parameters
as the back-up when the CEMS is unavailable because it would be a less
expensive approach. You could establish these operating parameter
limits, though, through CEMS measurements rather than comprehensive
performance test measures. In fact, it may be prudent for you to
evaluate relationships between various operating parameters for the
particulate matter control device ²¹⁹ and emission levels
recorded by the CEMS to develop a good predictive model of emissions.
You could then petition the Administrator (i.e., permitting officials)
under Sec. 63.8(f) to base compliance during CEMS malfunctions on
limits on alternative monitoring parameters derived from the predictive
model.
---------------------------------------------------------------------------

\219\ You are not restricted to those specified in Sec. 63.1209.
You may identify parameters for your source that correlate better
with particulate emissions than those we have specified generically.
---------------------------------------------------------------------------

2. Waiver of Feedstream Analysis Requirements. If you obtain
approval to use a CEMS for compliance under the petitioning provisions
of Sec. 63.8(f), we agree with the commenter's recommendation that you
should not be subject to the feedstream analysis requirements pertinent
to the pollutant you are measuring with a CEMS. As examples, if you use
a total mercury CEMS, you are not subject to a feedrate limit for
mercury, and if you operate an incinerator and use a particulate matter
CEMS, you are not subject to a feedrate limit for total ash.
If you are not subject to a feedrate limit for ash, metals, or
chorine because you use a CEMS for compliance, you are not subject to
the feedstream analysis requirements for these materials. As a
practical matter, however, this waiver may be moot because, as
discussed above, you will probably elect to comply with operating
parameter limits during CEMS malfunctions. However, a second, back-up
CEMS would also be acceptable. Absent a second CEMS, you would need to
establish feedrate limits for these materials as a back-up compliance
approach, and you would need to know the feedrate at any time given
that the CEMS may malfunction at any time. In addition, even when the
CEMS is operating within the performance specifications approved by the
permitting officials, you have the responsibility to minimize
exceedances by, for example, characterizing your feedstreams adequately
to enable you to take corrective measures if a CEMS-monitored emission
is approaching the standard. This level of feedstream characterization,
however, is less than the characterization required to establish and
comply with feedrate operating limits during CEMS malfunctions or
absent a CEMS.
3. Increase the Averaging Period for CEMS-Monitored Pollutants. The
averaging period for a CEMS-monitored pollutant should not be
artificially inflated (i.e., increased beyond the time required to
conduct three manual method test runs) because the standard would be
less stringent. See previous discussions on this issue.
4. Increase Emission Limits to Account for CEMS Uncertainty. We do
not agree with the suggestion that an emission limit needs to be
increased on a site-specific basis to accommodate CEMS inaccuracy and
imprecision (i.e., the acceptance criteria in the CEMS performance
specification that the source recommends and the permitting officials
approve will necessarily allow some inaccuracy and imprecision). Again,
we encourage sources to use a CEMS because it is a better indicator of
compliance than the promulgated compliance regime (i.e., periodic
emissions testing and operating parameter limits). We established the
final emission standards with achievability (through the use of the
prescribed compliance methods) in mind. We have accounted for the
inaccuracies and imprecisions in the emissions data in the process of
establishing the standard. See previous discussions in Part Four,
Section V.D. If the CEMS performance specification acceptance criteria
(that must be approved by permitting officials under a Sec. 63.8(f)
petition) were to allow the CEMS measurements to be more inaccurate or
imprecise than the promulgated compliance regime of performance testing
coupled with limits on operating parameters, the potential for improved
compliance assurance with the CEMS would be negated. Consequently, we
reject the idea that the standards need to be increased on a site-
specific basis as an incentive for sources to use CEMS.
5. Allow a CEMS Phase-In Period. CRWI's final three incentive
suggestions deal with the need for a CEMS phase-in period. This phase-
in period would be used to evaluate CEMS performance, including
identifying acceptable performance specification levels, maintenance
requirements, and measurement location. CRWI further suggested that the
Agency not penalize

[[Page 52934]]

a source if the CEMS does not work or has excessive downtime.
CRWI provided these comments in response to our proposal to require
compliance using CEMS and that sources document that the CEMS meets a
prescribed performance specification and correlation acceptance
criteria. Although we agree that a phase-in period would be
appropriate, the issue is moot given that we are not requiring the use
of CEMS.²²⁰ Prior to submitting a petition under
Sec. 63.8(f) to gain approval to use a CEMS, we presume a source will
identify the performance specification, correlation criteria, and
availability factors they believe are achievable. (We expect sources to
use the criteria we have proposed, as revised after considering
comments and further analysis and provided through guidance, as a point
of departure.) Thus, each source will have unlimited opportunity to
phase-in CEMS and subsequently recommend under Sec. 63.8(f) performance
specifications and correlation acceptance criteria.
---------------------------------------------------------------------------

\220\ Other than carbon monoxide, hydrocarbon, and oxygen CEMS.
---------------------------------------------------------------------------

We do not agree as a legal matter that we can state generically
that CEMS data obtained during the demonstration period are shielded
from enforcement if the CEMS data are credible and were to indicate
exceedance of an emission standard. In this situation, we cannot shield
a source from action by either by a regulatory agency or a citizen
suit. On balance, given our legal constraints, our policy desire to
have CEMS used for compliance, and uncertainty about the ultimate
accuracy of the CEMS data, we can use our enforcement discretion
whether to use particulate matter CEMS data as credible evidence in the
event the CEMS indicates an exceedance until the time the CEMS is
formally adopted as a compliance tool. Sources and regulators may
decide to draft a formal testing agreement that states that the CEMS
data obtained prior to the time the CEMS is accepted as a compliance
tool cannot be used as credible evidence of exceedance of an emission
standard.
D. What Are the Compliance Monitoring Requirements?
In this section we discuss the operating parameter limits that
ensure compliance with each emission standard.
1. What Are the Operating Parameter Limits for Dioxin/Furan?
You must maintain compliance with the dioxin/furan emission
standard by establishing and complying with limits on operating
parameters. See Sec. 63.1209(k). The following table summarizes these
operating parameter limits. All sources must comply with the operating
parameter limits applicable to good combustion practices. Other
operating parameter limits apply if you use the dioxin/furan control
technique to which they apply.

BILLING CODE 6560-50-P

[[Page 52935]]

[GRAPHIC] [TIFF OMITTED] TR30SE99.000

[[Page 52936]]

[GRAPHIC] [TIFF OMITTED] TR30SE99.001

BILLING CODE 6560-50-C

[[Page 52937]]

Dioxin/furan emissions from hazardous waste combustors are
primarily attributable to surface-catalyzed formation reactions
downstream from the combustion chamber when gas temperatures are in the
450 deg.F to 650 deg.F window (e.g., in an electrostatic precipitator
or fabric filter; in extensive ductwork between the exit of a
lightweight aggregate kiln and the inlet to the fabric filter; as
combustion gas passes through an incinerator waste heat recovery
boiler). In addition, dioxin/furan partition in two phases in stack
emissions: a portion is adsorbed onto particulate matter and a portion
is emitted as a vapor (gas). Because of these factors, and absent a
CEMS for dioxin/furan, we are requiring a combination of approaches to
control dioxin/furan emissions: (1) Temperature control at the inlet to
a dry particulate matter control device to limit dioxin/furan formation
in the control device; (2) operation under good combustion conditions
to minimize dioxin/furan precursors and dioxin/furan formation during
combustion; and (3) compliance with operating parameter limits on
dioxin/furan emission control equipment (e.g., carbon injection) that
you may elect to use.
We discuss below the operating parameter limits that apply to each
dioxin/furan control technique.
a. Combustion Gas Temperature Quench. To minimize dioxin/furan
formation in a dry particulate matter control device that suspends
collected particulate matter in the gas flow (e.g., electrostatic
precipitator, fabric filter), the rule limits the gas temperature at
the inlet to these control devices ²²¹ to levels occurring
during the comprehensive performance test. For lightweight aggregate
kilns, however, you must monitor the gas temperature at the kiln exit
rather than at the inlet to the particulate matter control device. This
is because the dioxin/furan emission standard for lightweight aggregate
kilns specifies rapid quench of combustion gas to 400 deg.F or less at
the kiln exit. ²²²
---------------------------------------------------------------------------

\221\ The temperature at the inlet to a cyclone separator used
as a prefiltering process for removing larger particles is not
limited. Cyclones do not suspend collected particulate matter in the
gas stream. Thus, these devices do not have the same potential to
enhance dioxin/furan formation as electrostatic precipitators and
fabric filters.
\222\ As discussed in Part Four, Section VIII, lightweight
aggregate kilns can have extensive ducting between the kiln exit and
the inlet to the fabric filter. If gas temperatures are limited at
the inlet to the fabric filter, substantial dioxin/furan formation
could occur in the ducting.
---------------------------------------------------------------------------

If your combustor is equipped with a wet scrubber as the initial
particulate matter control device, you are not required to establish
limits on combustion gas temperature at the scrubber. This is because
wet scrubbers do not suspend collected particulate matter in the gas
stream and gas temperatures are well below 400 deg.F in the
scrubber.²²³ Thus, scrubbers do not enhance surface-
catalyzed formation reactions.
---------------------------------------------------------------------------

\223\ For this reason, you are not required to document during
the comprehensive performance test that gas temperatures in the wet
scrubber are not greater than 400 deg.F. Also, we note that the 400
deg.F temperature limit of the dioxin/furan standard does not apply
to wet scrubbers, but rather to the inlet to a dry particulate
matter control device and the kiln exit of a lightweight aggregate
kiln.
---------------------------------------------------------------------------

We proposed limits on the gas temperature at the inlet to a dry
particulate matter control device (see 61 FR at 17424). Temperature
control at this location is important because surface-catalyzed
formation reactions can increase by a factor of 10 for every 150 deg.F
increase in temperature within the window of 350 deg.F to
approximately 700 deg.F. We received no adverse comments on the
proposal, and thus, are adopting this compliance requirement in the
final rule.
You must establish an hourly rolling average temperature limit
based on operations during the comprehensive performance test. The
hourly rolling average limit is established as the average of the test
run averages. See Part Five, Sections VII.B.1 and B.3 above for a
discussion on the approach for calculating limits from comprehensive
performance test data.
b. Good Combustion Practices. All hazardous waste combustors must
use good combustion practices to control dioxin/furan emissions by: (1)
Destroying dioxin/furan that may be present in feedstreams; (2)
minimizing formation of dioxin/furan during combustion; and (3)
minimizing dioxin/furan precursor that could enhance post-combustion
formation reactions. As proposed, you must establish and continuously
monitor limits on three key operating parameters that affect good
combustion: (1) Maximum hazardous waste feedrate; (2) minimum
temperature at the exit of each combustion chamber; and (3) residence
time in the combustion chamber as indicated by gas flowrate or kiln
production rate. We have also determined that you must establish
appropriate monitoring requirements to ensure that the operation of
each hazardous waste firing system is maintained. We discuss each of
these parameters below.
i. Maximum Hazardous Waste Feedrate. You must establish and
continuously monitor a maximum hazardous waste feedrate limit for
pumpable and nonpumpable wastes. See 61 FR at 17422. An increase in
waste feedrate without a corresponding increase in combustion air can
cause inefficient combustion that may produce (or incompletely destroy)
dioxin/furan precursors. You must also establish hazardous waste
feedrate limits for each location where waste is fed.
One commenter suggests that there is no reason to limit the
feedrate of each feedstream; a limit on the total hazardous waste
feedrate to each combustion chamber would be a more appropriate control
parameter. We concur in part. Limits are not established for each
feedstream. Rather, limits apply to total and pumpable wastes feedrates
for each feed location. Limits on pumpable wastes are needed because
the physical form of the waste can affect the rate of oxygen demand and
thus combustion efficiency. Pumpable wastes often will expose a greater
surface area per mass of waste than nonpumpable wastes, thus creating a
more rapid oxygen demand. If that demand is not satisfied, inefficient
combustion will occur. We also note that these waste feedrate limit
requirements are consistent with current RCRA permitting requirements
for hazardous waste combustors.
As proposed, you must establish hourly rolling average limits for
hazardous waste feedrate from comprehensive performance test data as
the average of the highest hourly rolling averages for each run. See
Part Five, Section VII.B.3 above for the rationale for this approach
for calculating limits from comprehensive performance test data.
ii. Minimum Gas Temperature in the Combustion Zone. You must
establish and continuously monitor limits on minimum gas temperature in
the combustion zone of each combustion chamber irrespective of whether
hazardous waste is fed into the chamber. See 61 FR at 17422. These
limits are needed because, as combustion zone temperatures decrease,
combustion efficiency can decrease resulting in increased formation of
(or incomplete destruction of) dioxin/furan precursors.²²⁴
---------------------------------------------------------------------------

\224\ See USEPA, ``Final Technical Support Document for
Hazardous Waste Combustor MACT Standards, Volume IV: Compliance with
the Hazardous Waste Combustor Standards'', February, 1999.
---------------------------------------------------------------------------

Monitoring combustion zone temperatures can be problematic,
however, because the actual burning zone temperature cannot be measured
at many units (e.g., cement kilns). For this reason, the BIF rule
requires

[[Page 52938]]

measurement of the ``combustion chamber temperature where the
temperature measurement is as close to the combustion zone as
possible.'' See Sec. 266.103(c)(1)(vii). In some cases, temperature is
measured at a location quite removed from the combustion zone due to
extreme temperatures and the harsh conditions at the combustion zone.
We discussed this issue at proposal and indicated that we were
concerned that monitoring at such remote locations may not accurately
reflect changes in combustion zone temperatures. See 61 FR at 17423.
We requested comment on possible options to address the issue.
Under one option, the final rule would have allowed the source to
identify a parameter that correlates with combustion zone temperature
and to provide data or information to support the use of that parameter
in the operating record. Under another option, the final rule would
have enabled regulatory officials on a case-specific basis to require
the use of alternate parameters as deemed appropriate, or to determine
that there is no practicable approach to ensure that minimum combustion
chamber temperature is maintained (and what the recourse/consequence
would be).
Some commenters recommend the status quo as identified by the BIF
rule requirements for monitoring combustion zone temperature. These
commenters suggest that more prescriptive requirements would not be
implementable for cement kilns because use of the temperature
measurement instrumentation would simply not be practicable under
combustion zone conditions in a cement kiln. We agree that combustion
zone temperature monitoring for certain types of sources requires some
site-specific considerations (as evidenced in our second proposed
option discussed above), and conclude that more specific language than
that used in the BIF rule to address this issue would not be
appropriate. Accordingly, we adopt language similar to the BIF rule in
today's final rule. You must measure the temperature of each combustion
chamber at a location that best represents, as practicable, the bulk
gas temperature in the combustion zone of that chamber. You are
required to identify the temperature measurement location and method in
the comprehensive performance test plan, which is subject to Agency
approval.
The temperature limit(s) apply to each combustion zone, as
proposed. See 61 FR at 17423. For incinerators with a primary and
secondary chamber, you must establish separate limits for the
combustion zone in each chamber.²²⁵ For kilns, you must
establish separate temperature limits at each location where hazardous
waste may be fired (e.g., the hot end where clinker is discharged; and
the upper end of the kiln where raw material is fed). We also proposed
to include temperature limits for hazardous waste fired at the midkiln.
One commenter indicates that it is technically infeasible to measure
temperature directly at the midkiln waste feeding location, however. We
agree that midkiln gas temperature is difficult to measure due to the
rotation of the kiln.²²⁶ Thus, the final rule allows
temperature measurement at the kiln back-end as a surrogate.
---------------------------------------------------------------------------

\225\ The temperature limits apply to a combustion chamber even
if hazardous waste is not burned in the chamber for two reasons.
First, an incinerator may rely on an afterburner that is fired with
a fuel other than hazardous waste to ensure good combustion of
organic compounds volatilized from hazardous waste in the primary
chamber. Second, MACT controls apply to total emissions (except
where the rule makes specific provisions), irrespective of whether
they derive from burning hazardous waste or other material, or from
raw materials.
\226\ See USEPA. ``Final Technical Support Document for
Hazardous Waste Combustor MACT Standards, Volume IV: Compliance with
the Hazardous Waste Combustor Standards'', February, 1999, for
further discussion.
---------------------------------------------------------------------------

You must establish an hourly rolling average temperature limit
based on operations during the comprehensive performance test. The
hourly rolling average limit is established as the average of the test
run averages. See Part Five, Sections VII.B.1 and B.3 above for a
discussion on the approach for calculating limits from comprehensive
performance test data.
iii. Maximum Flue Gas Rate or Kiln Production Rate. As proposed,
you must establish and continuously monitor a limit on maximum flue gas
flowrate or, as a surrogate, kiln production rate. See 61 FR at 17423.
Flue gas flowrates in excess of those that occur during comprehensive
performance testing reduce the time that combustion gases are exposed
to combustion chamber temperatures. Thus, combustion efficiency can
decrease potentially causing an increase in dioxin/furan precursors
and, ultimately, dioxin/furan emissions.²²⁷
---------------------------------------------------------------------------

\227\ We note that an increase in gas flowrate can also
adversely affect the performance of a dioxin/furan emission control
device (e.g., carbon injection, catalytic oxidizer). Thus, gas
flowrate is controlled for this reason as well.
---------------------------------------------------------------------------

For cement kilns and lightweight aggregate kilns, the rule allows
the use of production rate as a surrogate for flue gas flowrate. This
is the approach currently used for the BIF rule for these devices,
given that flue gas flowrate correlates with production rate (e.g.,
feedrate of raw materials or rate of production of clinker or
aggregate).
At proposal, however, we expressed concern that production rate may
not relate well to flue gas flowrate in situations where the moisture
content of the feed to the combustor changes dramatically. See 61 FR at
17423. Some commenters concur and also express concern that production
rate is not a reliable surrogate for flue gas flowrate because changes
in ambient temperature can cause increased heat rates and changes in
operating conditions can result in variability in excess air rates.
Based on an analysis of kiln processes, however, we conclude that these
issues should not be a concern. With respect to changes in moisture
content of the feed, kilns tend to have a steady and homogeneous waste
and raw material processing system. Thus, the feed moisture content
does not fluctuate widely, and variation in moisture content of the
stack does not significantly affect gas flowrate.²²⁸ Thus,
production rate should be an adequate surrogate for gas flowrate for
our purposes here.
---------------------------------------------------------------------------

\228\ See USEPA, ``Final TSD for hazardous Waste Combustor MACT
Standards, Volume IV: Compliance with the Hazardous Waste Combustor
Standards'', February, 1999 for further discussion.
---------------------------------------------------------------------------

You must establish a maximum gas flowrate or production rate limit
as the average of the maximum hourly rolling averages for each run of
the comprehensive performance test. See Part Five, Sections VII.B.3
above for the rationale for the approach for calculating limits from
comprehensive performance test data.
iv. Operation of Each Hazardous Waste Firing System. You must
recommend in the comprehensive performance test plan that you submit
for review and approval operating parameters, limits, and monitoring
approaches to ensure that each hazardous waste firing system continues
to operate as efficiently as demonstrated during the comprehensive
performance test.
It is important to maintain operation of the hazardous waste firing
system at levels of the performance test to ensure that the same or
greater surface area of the waste is exposed to combustion conditions
(e.g., temperature and oxygen). Oxidation takes place more quickly and
completely as the surface area per unit of mass of the waste increases.
If the firing system were to degrade over time such that smaller
surface area is exposed to combustion conditions, inefficient
combustion could result leading potentially to an increase in dioxin/
furan precursors.

[[Page 52939]]

At proposal, we discussed establishing operating parameter limits
only for minimum nozzle pressure and maximum viscosity of wastes fired
using a liquid waste injection system. In developing the final rule,
however, we determined that RCRA permit writers currently establish
operating parameter limits on each waste firing system to ensure
compliance with the RCRA destruction and removal efficiency (DRE)
standard. We are continuing the DRE requirement as a MACT standard, and
as discussed in Section VII.D.7 below, the DRE operating parameter
limits are identical to those required to maintain good combustion
practices for compliance with the dioxin/furan standard. This is
because compliance with the DRE standard is ensured by maintaining good
combustion practices. Consequently, we include a requirement to
establish limits on operating parameters for each waste or fuel firing
system as a measure of good combustion practices for the dioxin/furan
standard as well to be technically correct and for purposes of
completeness.²²⁹ Because this requirement is identical to an
existing RCRA requirement, it will not impose an incremental burden.
---------------------------------------------------------------------------

\229\ Because incomplete combustion of fuels (e.g., oil, coal,
tires) could contribute to increased dioxin/furan emissions by
producing dioxin/furan precursors, permitting official may require
(during review and approval of the comprehensive performance test
plan) that you establish limits on operating parameters for firing
systems in addition to those firing hazardous waste.
---------------------------------------------------------------------------

The rule does not prescribe generic operating parameters and how to
identify limits because, given the variety of firing systems and waste
and fuel properties, they are better defined on a site-specific basis.
Examples of monitoring parameters for a liquid waste firing system
would be, as proposed, minimum nozzle pressure established as an hourly
rolling average based on the average of the minimum hourly rolling
averages for each run, coupled with a limit on maximum waste viscosity.
The viscosity limit could be monitored periodically based on sampling
and analysis. Examples of monitoring parameters for a lance firing
system for sludges could be minimum pressure established as discussed
above, plus a limit on the solids content of the waste.
v. Consideration of Restrictions on Batch Size, Feeding Frequency,
and Minimum Oxygen Concentration. We proposed site-specific limits on
maximum batch size, batch feeding frequency, and minimum combustion gas
oxygen concentration as additional compliance requirements to ensure
good combustion practices. See 61 FR at 17423. After carefully
considering all comments, and for the reasons discussed below, we
conclude that the carbon monoxide and hydrocarbon emission standards
assure use of good combustion practices during batch feed operations.
This is because the carbon monoxide and hydrocarbon CEMS are reliable
and continuous indicators of combustion efficiency. In situations where
batch feed operating requirements may be needed to better assure good
combustion practices, however, we rely on the permit writer's
discretionary authority under Sec. 63.1209(g)(2) to impose additional
operating parameter limits on a site-specific basis.
Many hazardous waste combustors burn waste fuel in batches, such as
metal drums or plastic containers. Some containerized waste can
volatilize rapidly, causing a momentary oxygen-deficient condition that
can result in an increase in emissions of carbon monoxide, hydrocarbon,
and dioxin/furan precursors. We proposed to limit batch size, batch
feeding frequency, and minimum combustion gas oxygen concentration to
address this concern.
Commenters suggest that the proposed batch feed requirements (that
would limit operations to the smallest batch, the longest time
interval, and the maximum oxygen concentration demonstrated during the
comprehensive performance test) would result in extremely conservative
limits that would severely limit a source's ability to batch-feed
waste. Given these concerns and our reanalysis of the need for these
limits, we conclude that the carbon monoxide and hydrocarbon emission
standards will effectively ensure good combustion practices for most
batch feed operations. Consequently, the final rule does not require
limits for batch feed operating parameters.
Carbon monoxide or hydrocarbon monitoring may not be adequate for
all batch feed operations, however, to ensure good combustion practices
are maintained. We anticipate that permitting officials will determine
on a site-specific basis, typically during review of the initial
comprehensive performance test plan, whether limits on one or more
batch feed operating parameters need to be established to ensure good
combustion practices are maintained. This review should consider your
previous compliance history (e.g., frequency of automatic waste feed
cutoffs attributable to batch feed operations that resulted in an
exceedance of an operating limit or standard under RCRA regulations
prior to the compliance date), together with the design and operating
features of the combustor. Providing permitting officials the authority
under Sec. 63.1209(g)(2) to establish batch feed operating parameter
limits only where warranted precludes the need to impose the limits on
all sources.
Permitting officials may also determine that limits on batch feed
operating parameters are needed for a particular source based on the
frequency of automatic waste feed cutoffs after the MACT compliance
date. Permitting officials would consider cutoffs that are attributable
to batch feed operations and that result in an exceedance of an
operating parameter limit or the carbon monoxide or hydrocarbon
emission standard. Given that you must notify permitting officials if
you have 10 or more automatic waste feed cutoffs in a 60-day period
that result in an exceedance of an operating parameter limit or CEMS-
monitored emission standard, permitting officials should take the
opportunity to determine if batch feed operations contributed to the
frequency of exceedances. If so, permitting officials should use the
authority under Sec. 63.1209(g)(2) to establish batch feed operating
parameter limits.
Although we are not finalizing batch feed operating parameter
limits, we anticipate that permitting officials will require you
(during review and approval of the test plan) to simulate worst-case
batch feed operating conditions during the comprehensive performance
test when demonstrating compliance with the dioxin/furan and
destruction and removal efficiency standards. It would be inappropriate
for you to operate your batch feed system during the comprehensive
performance test in a manner that is not considered worst-case,
considering the types and quantities of wastes you may burn, and the
range of values you may encounter during operations for batch feed-
related operating parameters (e.g., oxygen levels, batch size and/or
btu content, waste volatility, batch feeding frequency).
To ensure that the CEMS-monitored carbon monoxide and hydrocarbon
emission standards ensure good combustion practices for batch feed
operations, the final rule includes special requirements to ensure that
``out-of-span'' carbon monoxide and hydrocarbon CEMS readings are
adequately accounted for. We proposed batch feed operating parameter
limits in part because of concern that the carbon monoxide and
hydrocarbon CEMS may not accurately calculate hourly rolling averages
when you encounter emission concentrations that exceed the span of the
CEMS. This is an important

[[Page 52940]]

consideration because batch feed operations have the potential to
generate large carbon monoxide or hydrocarbon spikes--large enough at
times to exceed the span of the detector. When this occurs, the CEMS in
effect ``pegs out'' and the analyzer may only record data at the upper
end of its span, while in fact carbon monoxide/hydrocarbon
concentrations are much higher. In these situations, the true carbon
monoxide/hydrocarbon concentration is not being used to calculate the
hourly rolling average. This has two significant consequences of
concern to us.²³⁰
---------------------------------------------------------------------------

\230\ As explained in Part Five, Section VII.D.4 of the text,
this concern is not limited to batch feed operations.
---------------------------------------------------------------------------

First, you could experience a large carbon monoxide/hydrocarbon
spike (as a result of feeding a large or highly volatile batch) which
causes the monitor to ``peg out.'' In this situation, the CEMS would
record carbon monoxide/hydrocarbon levels that are lower than actual
levels. This under-reporting of emission levels would result in an
hourly rolling average that is biased low. You may in fact be exceeding
the emission standard even though the CEMS indicates you are in
compliance. Second, if a carbon monoxide/hydrocarbon excursion causes
an automatic waste feed cutoff, you may be allowed to resume hazardous
waste burning much sooner than you would be allowed if the CEMS were
measuring true hourly rolling averages. This is because you must
continue monitoring operating parameter limits and CEMS-monitored
emission standards after an automatic waste feed cutoff and you may not
restart hazardous waste feeding until all limits and CEMS-monitored
emission standards are within permissible levels.²³¹
---------------------------------------------------------------------------

\231\ A higher hourly rolling average carbon monoxide level that
is above the standard requires a longer period of time to drop below
the standard.
---------------------------------------------------------------------------

As explained in Part Five, Section VII.D.4 below, we have resolved
these ``out of span'' concerns by including special provisions in
today's rule for instances when you encounter hydrocarbon/carbon
monoxide CEMS measurements that are above the upper span required by
the performance specifications.²³² These special provisions
require you to assume hydrocarbons and carbon monoxide are being
emitted at levels of 500 ppmv and 10,000 ppmv, respectively, when any
one minute average exceeds the upper span level of the
detector.²³³ Although we did not propose these special
provisions, they are a logical outgrowth of the proposed batch feed
requirements and commenters concerns about those requirements.
---------------------------------------------------------------------------

\232\ The carbon monoxide CEMS upper span level for the high
range is 3000 ppmv. The upper span level for hydrocarbon CEMS is 100
ppmv. (See Performance Specifications 4B and 8A in Appendix B, part
60, and the appendix to subpart EEE, part 63--Quality Assurance
Procedures for Continuous Emissions Monitors Used for Hazardous
Waste Combustors, Section 6.3).
\233\ You would not be required to assume these one-minute
values if you use a CEMS that meets the performance specifications
for a range that is higher than the recorded one-minute average. In
this case, the CEMS must meet performance specifications for the
higher range as well as the ranges specified in the performance
specifications in Appendix B, part 60. See Sec. 63.1209 (a)(3) and
(a)(4).
---------------------------------------------------------------------------

For the reasons discussed above, we conclude that national
requirements for batch feed operating parameter limits are not
warranted.
c. Activated Carbon Injection. If your combustor is equipped with
an activated carbon injection system, you must establish and comply
with limits on the following operating parameters: Good particulate
matter control, minimum carbon feedrate, minimum carrier fluid flowrate
or nozzle pressure drop, and identification of the carbon brand and
type or the adsorption characteristics of the carbon. These are the
same compliance parameters that we proposed. See 61 FR at 17424.
i. Good Particulate Matter Control. You must comply with the
operating parameter limits for particulate matter control (see
discussion in Section VII.D.6 below and Sec. 63.1209(m)) because carbon
injection controls dioxin/furan in conjunction with particulate matter
control. Dioxin/furan is adsorbed onto carbon that is injected into the
combustion gas, and the carbon is removed from stack gas by a
particulate control device.
Although we proposed to require good particulate matter control as
a control technique for dioxin/furan irrespective of whether carbon
injection was used, commenters indicate that we have no data
demonstrating the relationship between particulate matter and dioxin/
furan emissions. Commenters further indicate that dioxin/furan occur
predominately in the gas phase, not adsorbed onto particulate. We agree
with commenters that hazardous waste combustors operating under the
good combustion practices required by this final rule are not likely to
have significant carbon particulates in stack gas (i.e., because
carbonaceous particulates (soot) are indicative of poor combustion
efficiency). Thus, unless activated carbon injection is used as a
control technique, dioxin/furan will occur predominately in the gas
phase. We therefore conclude that requiring good particulate control as
a control technique for dioxin/furan is not warranted unless a source
is equipped with activated carbon injection.²³⁴
---------------------------------------------------------------------------

\234\ We discuss below, however, that good particulate matter
control is also required if a source is equipped with a carbon bed.
This is to ensure that particulate control upstream of the carbon
bed is maintained to performance test levels to prevent blinding of
the bed and loss of removal efficiency.
---------------------------------------------------------------------------

ii. Minimum Carbon Feedrate. As proposed, you must establish and
continuously monitor a limit on minimum carbon feedrate to ensure that
dioxin/furan removal efficiency is maintained. You must establish an
hourly rolling average feedrate limit based on operations during the
comprehensive performance test. The hourly rolling average limit is
established as the average of the test run averages. See Part Five,
Sections VII.B.1 and B.3 above for a discussion of the approach for
calculating limits from comprehensive performance test data.
iii. Minimum Carrier Fluid Flowrate or Nozzle Pressure Drop. A
carrier fluid, gas or liquid, is necessary to transport and inject the
carbon into the gas stream. As proposed, you must establish and
continuously monitor a limit on either minimum carrier fluid flowrate
or pressure drop across the nozzle to ensure that the flow and
dispersion of the injected carbon into the flue gas stream is
maintained.
We proposed to require you to base the limit on the carbon
injection manufacturer's specifications. One commenter notes that there
are no manufacturer specifications for carrier gas flowrate or pressure
drop. Therefore, the final rule allows you to use engineering
information and principles to establish the limit for minimum carrier
fluid flowrate or pressure drop across the injection nozzle. You must
identify the limit and the rationale for deriving it in the
comprehensive performance test plan that you submit for review and
approval.
iv. Identification of Carbon Brand and Type or Adsorption
Properties. You must either identify the carbon brand and type used
during the comprehensive performance test and continue using that
carbon, or identify the adsorption properties of that carbon and use a
carbon having equivalent or better properties. This will ensure that
the carbon's adsorption properties are maintained.²³⁵
---------------------------------------------------------------------------

\235\ Examples of carbon properties include specific surface
area, pore volume, average pore size, pore size distribution, bulk
density, porosity, carbon source, impregnation, and activization
procedure. See USEPA, ``Technical Support Document for HWC MACT
Standards, Volume IV: Compliance with the HWC MACT Standards,'' July
1999.
---------------------------------------------------------------------------

We proposed to require you to use the same brand and type of carbon
that was

[[Page 52941]]

used during the comprehensive performance test. Commenters object to
this requirement and suggest that they should have the option of using
alternative types of carbon that would achieve equivalent or better
performance than the carbon used during the performance test. We
concur, and the final rule allows you to document in the comprehensive
performance test plan key parameters that affect adsorption and the
limits you have established on those parameters based on the carbon to
be used during the performance test. You may substitute at any time a
different brand or type of carbon provided that the replacement has
equivalent or improved properties and conforms to the key sorbent
parameters you have identified. You must include in the operating
record written documentation that the substitute carbon will provide
the same level of control as the original carbon.
d. Activated Carbon Bed. If your combustor is equipped with an
activated carbon bed, you must establish and comply with limits on the
following operating parameters: good particulate matter control;
maximum age of each carbon bed segment; identification of carbon brand
and type or adsorption properties, and maximum temperature at the inlet
or exit of the bed. These are the same compliance parameters that we
proposed. See 61 FR at 17424.
i. Good Particulate Matter Control. You must comply with the
operating parameter limits for particulate matter control (see
discussion in Section VII.D.6 below and Sec. 63.1209(m)). If good
control of particulate matter is not maintained prior to the inlet to
the carbon bed, particulate matter could contaminate the bed and affect
dioxin/furan removal efficiency. In addition, if particulate matter
control is used downstream from the carbon bed, those controls must
conform to good particulate matter control. This is because this
``polishing'' particulate matter control device may capture carbon-
containing dioxin/furan that may escape from the carbon bed. Thus, the
efficiency of this polishing control must be maintained to ensure
compliance with the dioxin/furan emission standard.
ii. Maximum Age of Each Bed Segment. As proposed, you must
establish a maximum age of each bed segment to ensure that removal
efficiency is maintained. Because activated carbon removes dioxin/furan
(and mercury) by adsorption, carbon in the bed becomes less effective
over time as the active sites for adsorption become occupied. Thus, bed
age is an important operating parameter.
At proposal, we requested comment on using carbon aging or some
form of a breakthrough calculation to identify a limit on carbon age.
See 61 FR at 17424. A breakthrough calculation would give a theoretical
minimum carbon change-out schedule that you could use to ensure that
breakthrough (i.e., the dramatic reduction in efficiency of the carbon
bed due to too many active sites being occupied) does not occur.
Commenters indicate that carbon effectiveness depends on the carbon
bed age and pollutant types and concentrations in the gas streams, and
therefore a carbon change-out schedule should be based on a
breakthrough calculation rather than carbon age. We agree that a
breakthrough calculation may be a better measurement of carbon
effectiveness, but it would be difficult to define generically for all
situations. A breakthrough calculation could be performed only after
experimentation determines the relationship between incoming adsorbed
chemicals and the adsorption rate of the carbon. The adsorption rate of
carbon could be determined experimentally, but the speciation of
adsorbed chemicals in a flue gas stream is site-specific and may vary
greatly at a given site over time.
We conclude that because carbon age contributes to carbon
ineffectiveness, it serves as an adequate surrogate and is less
difficult to implement on a national basis. Therefore, the rule
requires sources to identify maximum carbon age as the maximum age of
each bed segment during the comprehensive performance test. Carbon age
is measured in terms of the cumulative volume of combustion gas flow
through the carbon since its addition to the bed. Sources may use the
manufacturer's specifications rather than actual bed age during the
initial comprehensive performance test to identify the initial limit on
maximum bed age. If you elect to use manufacturer's specifications for
the initial limit on bed age, you must also recommend in the
comprehensive performance test plan submitted for review and approval a
schedule of dioxin/furan testing prior to the confirmatory performance
test that will confirm that the manufacturer's specification of bed age
is sufficient to ensure that you maintain compliance with the emission
standard.
If either existing or new sources prefer to use some form of
breakthrough calculation to establish maximum bed age, you may petition
permitting officials under Sec. 63.1209(g)(1) ²³⁶ to apply
for an alternative monitoring scheme.
---------------------------------------------------------------------------

\236\ We have incorporated the alternative monitoring provisions
of Sec. 63.8(f) in Sec. 63.1209(g)(1) so that alternative monitoring
provisions for nonCEMS CMS can be implemented by authorized States.
The alternative monitoring provisions of Sec. 63.1209(g)(1) do not
apply to CEMS, however. The alternative monitoring provisions of
Sec. 63.8(f) continue to apply to CEMS because implementation of
those provisions is not eligible to be delegated to States at this
time.
---------------------------------------------------------------------------

iii. Identification of Carbon Brand and Type or Adsorption
Properties. You must either identify the carbon brand and type used
during the comprehensive performance test and continue using that
carbon, or identify the adsorption properties of that carbon and use a
carbon having equivalent or better properties. This requirement is
identical to that discussed above for activated carbon injection
systems.
iv. Maximum Temperature at the Inlet or Exit of the Bed. You must
establish and continuously monitor a limit on the maximum temperature
at the inlet or exit of the carbon bed. This is because a combustion
gas temperature spike can cause adsorbed dioxin/furan (and mercury) to
desorb and reenter the gas stream. In addition, the adsorption
properties of carbon are adversely affected at higher temperatures.
At proposal, we requested comment on whether it would be necessary
to control temperature at the inlet to the carbon bed. See 61 FR at
17425. Some commenters support temperature control noting the concern
that temperature spikes could cause desorption of dioxin/furan (and
mercury). We concur, and are requiring you to establish a maximum
temperature limit at the inlet or exit of the bed. We are allowing you
the option of measuring temperature at either end of the bed to give
you greater flexibility in locating the temperature continuous
monitoring system. Monitoring temperature at either end of the bed
should be adequate to ensure that bed temperatures are maintained at
levels not exceeding those during the comprehensive performance test
(because the temperature remains relatively constant across the bed).
You must establish an hourly rolling average temperature limit
based on operations during the comprehensive performance test. The
hourly rolling average limit is established as the average of the test
run averages. See Part Five, Sections VII.B.1 and B.3 above for a
discussion of the approach for calculating limits from comprehensive
performance test data.
e. Catalytic Oxidizer. If your combustor is equipped with a
catalytic oxidizer, you must establish and comply with limits on the
following operating parameters: minimum gas temperature

[[Page 52942]]

at the inlet of the catalyst; maximum age in use; catalyst replacement
specifications; and maximum flue gas temperature at the inlet of the
catalyst. These are the same compliance parameters that we proposed.
See 61 FR at 17425.
Catalytic oxidizers used to control stack emissions are similar to
those used in automotive and industrial applications. The flue gas
passes over catalytic metals, such as palladium and platinum, supported
by an alumina washcoat on some metal or ceramic substrate. When the
flue gas passes through the catalyst, a reaction takes place similar to
combustion, converting hydrocarbons to carbon monoxide, then carbon
dioxide. Catalytic oxidizers can also be ``poisoned'' by lead and other
metals in the same manner as automotive and industrial catalysts.
i. Minimum Gas Temperature at the Inlet of the Catalyst. You must
establish and continuously monitor a limit on the minimum flue gas
temperature at the inlet of the catalyst to ensure that the catalyst is
above light-off temperature. Light-off temperature is that minimum
temperature at which the catalyst is hot enough to catalyze the
reactions of hydrocarbons and carbon monoxide.
You must establish an hourly rolling average temperature limit
based on operations during the comprehensive performance test. The
hourly rolling average limit is established as the average of the test
run averages.
ii. Maximum Time In-Use. You must establish a limit on the maximum
time in-use of the catalyst because a catalyst is poisoned and
generally degraded over use. You must establish the limit based on the
manufacturer's specifications.
iii. Catalytic Metal Loading, Maximum Space-Time, and Substrate
Construct. When you replace a catalyst, the replacement must be of the
same design to ensure that destruction efficiency is maintained.
Consequently, the rule requires that you specify the following catalyst
properties: Loading of catalytic metals; space-time; and monolith
substrate construction.
Catalytic metal loading is important because, without sufficient
catalytic metal on the catalyst, it does not function properly. Also,
some catalytic metals are more efficient than others. Therefore, the
replacement catalyst must have at least the same catalytic metal
loading for each catalytic metal as the catalyst used during the
comprehensive performance test.
Space-time, expressed in inverse seconds (s^-1), is
defined as the maximum rated volumetric flow through the catalyst
divided by the volume of the catalyst. This is important because it is
a measure of the gas flow residence time and, hence, the amount of time
the flue gas is in the catalyst. The longer the gas is in the catalyst,
the more time the catalyst has to cause hydrocarbons and carbon
monoxide to react. Replacement catalysts must have the same or lower
space-time as the one used during the comprehensive performance test.
Substrate construction is also an important parameter affecting
destruction efficiency of the catalyst. Three factors are important.
First, substrates for industrial applications are typically monoliths,
made of rippled metal plates banded together around the circumference
of the catalyst. Ceramic monoliths and pellets can also be used.
Because of the many types of substrates, you must use the same
materials of construction, monolith or pellets and metal or ceramic,
used during the comprehensive performance test as replacements. Second,
monoliths form a honeycomb like structure when viewed from one end. The
pore density (i.e., number of pores per square inch) is critical
because the pores must be small enough to ensure intimate contact
between the flue gas and the catalyst but large enough to allow
unrestricted flow through the catalyst. Therefore, if you use a
monolith substrate during the comprehensive performance test, the
replacement catalyst must have the same pore density. Third, catalysts
are supported by a washcoat, typically alumina. We require that
replacement catalysts have the same type and loading of washcoat as was
on the catalyst used during the comprehensive performance test.
iv. Maximum Flue Gas Temperature at the Inlet to the Catalyst. You
must establish and continuously monitor a limit on maximum flue gas
temperature at the inlet to the catalyst. Inlet temperature is
important because sustained high flue gas temperature can result in
sintering of the catalyst, degrading its performance. You must
establish the limit as an hourly rolling average, based on manufacturer
specifications.
In the proposed rule, we would have allowed a waiver from these
operating parameter limits if you documented to the Administrator that
establishing limits on other operating parameters would be more
appropriate to ensure that the dioxin/furan destruction efficiency of
the oxidizer is maintained after the performance test. See 61 FR at
17425. We are not finalizing a specific waiver for catalytic oxidizer
parameters because you are eligible to apply for the same relief under
the existing alternative monitoring provisions of Sec. 63.1209(g)(1).
f. Dioxin/Furan Formation Inhibitor. If you feed a dioxin/furan
formation inhibitor into your combustor as an additive (e.g., sulfur),
you must: (1) Establish a limit on minimum inhibitor feedrate; and (2)
identify either the brand and type of inhibitor or the properties of
the inhibitor.
i. Minimum Inhibitor Feedrate. As proposed, you must establish and
continuously monitor a limit on minimum inhibitor feedrate to help
ensure that dioxin/furan formation reactions continue to be inhibited
at levels of the comprehensive performance test. See 61 FR at 17425.
You must establish an hourly rolling average feedrate limit based on
operations during the comprehensive performance test. The hourly
rolling average limit is established as the average of the test run
averages.
This minimum inhibitor feedrate pertains to additives to
feedstreams, not naturally occurring inhibitors that may be found in
fossil fuels, hazardous waste, or raw materials. At proposal, we
requested comment on whether it would be appropriate to establish
feedrate limits on the amount of naturally occurring inhibitors based
on levels fed during the comprehensive performance test. See 61 FR at
17425. For example, it is conceivable that a source would choose to
burn high sulfur fuel or waste only during the comprehensive
performance test and then switch back to low sulfur fuels or waste
after the test, thus reducing dioxin/furan emissions during the
comprehensive test to levels that would not be maintained after the
test. Commenters do not provide information on this matter and we do
not have enough information on the types or effects of naturally
occurring substances that may act as inhibitors. Therefore, the final
rule does not establish limits on naturally occurring inhibitors.
Permitting officials, however, may choose to address the issue of
naturally occurring inhibitors when warranted during review of the
comprehensive performance test plan. (See discretionary authority of
permitting officials under Sec. 63.1209(g)(2) to impose additional or
alternative operating parameter limits on a site-specific basis.)
ii. Identification of Either the Brand and Type of Inhibitor or the
Properties of the Inhibitor. As proposed, you must either identify the
inhibitor brand and type used during the comprehensive performance test
and continue using that inhibitor, or identify the properties of that
inhibitor that affect its ability to inhibit dioxin/furan formation
reactions and use an inhibitor having equivalent

[[Page 52943]]

or better properties. This requirement is identical to that discussed
above for activated carbon systems.
2. What Are the Operating Parameter Limits for Mercury?
You must maintain compliance with the mercury emission standard by
establishing and complying with limits on operating parameters. See
Sec. 63.1209(l). The following table summarizes these operating
parameter limits. All sources must comply with the limits on mercury
feedrate. Other operating parameter limits apply if you use the mercury
control technique to which they apply.

[GRAPHIC] [TIFF OMITTED] TR30SE99.002

Mercury emissions from hazardous waste combustors are controlled by
controlling the feedrate of mercury, wet scrubbing to remove soluble
mercury species (e.g, mercuric chloride), and carbon adsorption. We
discuss below the operating parameter limits that apply to each control
technique. We also discuss why we are not limiting the temperature at
the inlet to the dry particulate matter control device as a control
parameter for mercury.
a. Maximum Mercury Feedrate. As proposed, you must establish and
comply with a maximum total feedrate limit for mercury for all
feedstreams. See 61 FR at 17428. The amount of mercury fed into the
combustor directly affects emissions and the removal efficiency of
emission control equipment. To establish and comply with the feedrate
limit, you must sample and analyze and continuously monitor the
flowrate of all feedstreams (including hazardous waste, raw materials,
and other fuels and additives) except natural gas, process air, and
feedstreams from vapor recovery systems for mercury content.\237\ As
proposed, you must establish a maximum 12-hour rolling average feedrate
limit based on operations during the comprehensive performance test as
the average of the test run averages.
---------------------------------------------------------------------------

\237\ See discussion in Section VII.D.3. below in the text for
rationale for exempting these feedstreams for monitoring for mercury
content.
---------------------------------------------------------------------------

Rather than establish mercury feedrate limits as the levels fed
during the comprehensive performance test, you may request as part of
your performance test plan to use the mercury feedrates and associated
emission rates during the performance test to extrapolate to higher
allowable feedrate limits and emission rates. See Section VII.D.3 below
for a discussion of the rationale and procedures for obtaining approval
to extrapolate metal feedrates.
In addition, you may use the performance test waiver provision
under Sec. 63.1207(m) to document compliance with the emission
standard. Under that provision, you must monitor the total mercury
feedrate from all feedstreams and the gas flowrate and document that
the maximum theoretical emission concentration does not exceed the
mercury emission standard. Thus, this is another compliance approach
where you would not establish feedrate limits on mercury during the
comprehensive performance test.
b. Wet Scrubbing. As proposed, if your combustor is equipped with a
wet scrubber, you must establish and comply with limits on the same
operating parameters (and in the same manner) that apply to compliance
assurance with the hydrochloric acid/chlorine gas emission standard for
wet scrubbers. See Section VII.D.5 below for a discussion of those
parameters.
c. Activated Carbon Injection. As proposed, if your combustor is
equipped with an activated carbon injection system, you must establish
and comply with limits on the same operating parameters (and in the
same manner) that apply to compliance assurance with the dioxin/furan
emission standard for activated carbon injection systems.
d. Activated Carbon Bed. As proposed, if your combustor is equipped
with an activated carbon bed, you must establish and comply with limits
on the same operating parameters (and in the same manner) that apply to
compliance assurance with the dioxin/furan emission standard for
activated carbon beds.
e. Consideration of a Limit on Maximum Inlet Temperature to a Dry
Particulate Matter Control Device. The final rule does not require you
to control inlet temperature to a dry particulate

[[Page 52944]]

matter air pollution control device to control mercury emissions. At
proposal, we expressed concern that high inlet temperatures to a dry
particulate matter control device could cause low mercury removal
efficiency because mercury volatility increases with increasing
temperature. See 61 FR at 17428. Therefore, we proposed to limit inlet
temperatures to levels during the comprehensive performance test.
Commenters suggest that a maximum inlet temperature for dry
particulate matter control devices is not needed because mercury is
generally highly volatile within the range of inlet temperatures of all
dry particulate matter control devices. We are persuaded by the
commenters that inlet temperature to these devices is not critically
important to mercury control, although temperature can potentially have
an impact on the volatility of certain mercury species (e.g., oxides).
We conclude that the other operating parameter limits are sufficient to
ensure compliance with the mercury emission standard. In particular, we
note that a limit on maximum inlet temperature to these control devices
is required for compliance assurance with the dioxin/furan,
semivolatile metal, and low volatile metal emission standards.
3. What Are the Operating Parameter Limits for Semivolatile and Low
Volatile Metals?
You must maintain compliance with the semivolatile metal and low
volatile metal emission standards by establishing and complying with
limits on operating parameters. See Sec. 63.1209(n). The following
table summarizes these operating parameter limits. All sources must
comply with the limits on feedrates of semivolatile metals, low
volatile metals, and chlorine. Other operating parameter limits apply
depending on the type of particulate matter control device you use.

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[[Page 52946]]

Semivolatile and low volatile metal emissions from hazardous waste
combustors are controlled by controlling the feedrate of the metals and
particulate matter emissions. In addition, because chlorine feedrate
can affect the volatility of metals and thus metals levels in the
combustion gas, and because the temperature at the inlet to the dry
particulate matter control device can affect whether the metal is in
the vapor (gas) or solid (particulate) phase, control of these
parameters is also important to control emissions of these metals. We
discuss below the operating parameter limits that apply to each control
technique. We also discuss use of metal surrogates during performance
testing, provisions for allowing extrapolation of performance test
feedrate levels to calculate metal feedrate limits, and conditional
waiver of the limit on low volatile metals in pumpable feedstreams.
a. Good Particulate Matter Control. As proposed, you must comply
with the operating parameter limits for particulate matter control (see
discussion in Section VII.D.6 below and Sec. 63.1209(m)) because
semivolatile and low volatile metals are primarily in the solid
(particulate) phase at the gas temperature (i.e., 400 deg.F or lower)
of the particulate matter control device. Thus, these metals are
largely removed from flue gas as particulate matter.
b. Maximum Inlet Temperature to Dry Particulate Matter Control
Device. As proposed, you must establish and continuously monitor a
limit on the maximum temperature at the inlet to a dry particulate
matter control device. Although most semivolatile and low volatile
metals are in the solid, particulate phase at the temperature at the
inlet to the dry control device mandated by today's rule (i.e.,
400 deg.F or lower), some species of these metals remain in the vapor
phase. We are requiring a limit on maximum temperature at the inlet to
the control device to ensure that the fraction of these metals that are
volatile (and thus not controlled by the particulate matter control
device) does not increase during operations after the comprehensive
performance test.
As proposed, you must establish an hourly rolling average
temperature limit based on operations during the comprehensive
performance test. The hourly rolling average limit is established as
the average of the test run averages. See Part Five, Sections VII.B.1
and B.3 above for a discussion of the approach for calculating limits
from comprehensive performance test data.
Commenters suggest that this limit may conflict with the maximum
temperature limit at the inlet to the particulate matter control device
that is also required for compliance assurance with the dioxin/furan
emission standard. We do not understand commenters' concern. If for
some reason the dioxin/furan and metals emissions tests are not
conducted simultaneously, the governing temperature limit will be the
lower of the limits established from the separate tests. This provides
compliance assurance for both standards.
c. Maximum Semivolatile and Low Volatile Metals Feedrate Limits.
You must establish limits on the maximum total feedrate of both
semivolatile metals and low volatile metals from all feedstreams at
levels fed during the comprehensive performance test. Metals feedrates
are related to emissions in that, as metals feedrates increase at a
source, metals emissions increase. See Part Four, Section II.A above
for discussion on the relationship between metals feedrates and
emissions. Thus, metals feedrates are an important control technique.
For low volatile metals, you must also establish a limit on the
maximum total feedrate of pumpable liquids from all feedstreams. The
rule requires a separate limit for pumpable feedstreams because metals
present in pumpable feedstreams may partition between the combustion
gas and bottom ash (or kiln product) at a higher rate than metals in
nonpumpable feedstreams (i.e., low volatile metals in pumpable
feedstreams tend to partition primarily to the combustion gas). The
rule does not require a separate limit for semivolatile metals in
pumpable feedstreams because partitioning between the combustion gas
and bottom ash or product for these metals does not appear to be
affected by the physical state of the feedstream.²³⁸
---------------------------------------------------------------------------

\238\ See USEPA., ``Technical Support Document for HWC MACT
Standards, Volume IV: Compliance with the MACT Standards,'' February
1998.
---------------------------------------------------------------------------

To establish and comply with the feedrate limits, you must sample
and analyze and continuously monitor the flowrate of all feedstreams
(including hazardous waste, raw materials, and other fuels and
additives) except natural gas, process air, and feedstreams from vapor
recovery systems for semivolatile and low volatile metals content. As
proposed, you must establish maximum 12-hour rolling average feedrate
limits based on operations during the comprehensive performance test as
the average of the test run averages.
i. Use of Metal Surrogates. You may use one metal within a
volatility group as a surrogate during comprehensive performance
testing for other metals in that volatility group. For example, you may
use chromium as a surrogate during the performance test for all low
volatile metals. Similarly, you may use lead as a surrogate for
cadmium, the other semivolatile metal. This is because the metals
within a volatility group have generally the same volatility. Thus,
they will generally be equally difficult to control with an emissions
control device.
In addition, you may use either semivolatile metal as a surrogate
for any low volatile metal because semivolatile metals will be more
difficult to control than low volatile metals.²³⁹ This will
help alleviate concerns regarding the need to spike each metal during
comprehensive performance testing. If you want to spike metals, you
need not spike each metal to comply with today's rule but only one
metal within a volatility group (or potentially one semivolatile metal
for both volatility groups).
---------------------------------------------------------------------------

\239\ This is because a greater portion of semivolatile metals
volatilize in the combustion chamber and condenses in the flue gas
on small particulates or as fume. The major portion of low volatile
metals in flue gas are entrained on larger particulates (rather than
condensing from volatile species) and are thus easier to remove with
a particulate control device.
---------------------------------------------------------------------------

ii. Extrapolation of Performance Test Feedrate Levels to Calculate
Metal Feedrate Limits.²⁴⁰ You may request under
Sec. 63.1209(n)(2)(ii) to use the metal feedrates and emission rates
associated with the comprehensive performance test to extrapolate
feedrate limits and emission rates at levels higher than demonstrated
during the performance test. Extrapolation can be advantageous because
it avoids much of the spiking that sources normally undertake during
compliance testing and the associated costs, risks to operating and
testing personnel, and environmental loading from emissions.
---------------------------------------------------------------------------

\240\ Although this extrapolation discussion is presented in
context of semivolatile and low volatile metal feedrates, similar
provisions could be implemented for mercury feedrates.
---------------------------------------------------------------------------

Under an approved extrapolation approach, you would be required to
feed metals at no less than normal rates to narrow the amount of
extrapolation requested. Further, we expect that some spiking would be
desired to increase confidence in the measured, performance test
feedrate levels that will be used to project feedrate limits (i.e., the
errors associated with sampling and analyzing heterogeneous feedstreams
can be minimized by spiking known quantities). Extrapolation approaches
that request feedrate limits that are significantly higher than the
historical range of

[[Page 52947]]

feedrates should not be approved. Extrapolated feedrate limits should
be limited to levels within the range of the highest historical
feedrates for the source. We are taking this policy position to avoid
creating an incentive to burn wastes with higher than historical levels
of metals. Metals are not destroyed by combustion but rather are
emitted as a fraction of the amount fed to the combustor. If you want
to burn wastes with higher than historical levels of metals, you must
incur the costs and address the hazards to plant personnel and testing
crews associated with spiking metals into your feedstreams during
comprehensive performance testing.
Although we also investigated downward interpolation (i.e., between
the measured feedrate and emission level and zero), we are concerned
that downward interpolation may not be conservative. Our data indicates
that system removal efficiency can decrease as metal feedrate
decreases. Thus, actual emissions may be higher than emissions
projected by interpolation for lower feedrates. Consequently, we are
not allowing downward interpolation.
We are not specifying an extrapolation methodology to provide as
much flexibility as possible to consider extrapolation methodologies
that would best meet individual needs. We have investigated
extrapolation approaches ²⁴¹ and discussed in the May 1997
NODA a statistical extrapolation methodology. Commenters raise
concerns, however, about defining a single acceptable extrapolation
method. They note that other methods might be developed in the future
that prove to be better, especially for a given source. We agree that
the approach discussed in the NODA may be too inflexible and are not
promulgating it today.²⁴² Consequently, today's rule does
not specify a single method but allows you to recommend a method for
review and approval by permitting officials.
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\241\ See USEPA, ``Draft Technical Support Document for HWC MACT
Standards (NODA), Volume III: Evaluation of Metal Emissions Database
to Investigate Extrapolation and Interpolation Issues,'' April 1997.
\242\ We plan to develop guidance on approaches that provide
greater flexibility.
---------------------------------------------------------------------------

Your recommended extrapolation methodology must be included in the
performance test plan. See Sec. 63.1207(f)(1)(x). Permitting officials
will review the methodology considering in particular whether: (1)
Performance test metal feedrates are appropriate (i.e., whether
feedrates are at least at normal levels, whether some level of spiking
would be appropriate depending on the heterogeneity of the waste, and
whether the physical form and species of spiked material is
appropriate); and (2) the requested, extrapolated feedrates are
warranted considering historical metal feedrate data.
We received comments both in favor of and in opposition to metals
extrapolation and interpolation. Those in favor suggest extrapolation
would simplify the comprehensive performance test procedure, reduce
costs, and decrease emissions during testing. Those in opposition are
concerned about: (1) Whether there is a predictable relationship
between feedrates and emission rates; (2) the possibility of higher
overall metals loading to the environment over the life of the facility
(i.e., because higher feedrate limits would be relatively easy to
obtain); (3) the difficulty in defining a ``normal'' feedrate for
facilities with variable metal feeds; and (4) whether all conditions
influencing potential metals emissions, such as combustion temperature
and metal compound speciation, could be adequately considered.
Given the pros and cons associated with various extrapolation
methodologies and policies, we are still concerned that sources would
be able to: (1) Feed metals at higher rates without a specific
compliance demonstration of the associated metals emissions; and (2)
obtain approval to feed metals at higher levels than normal, even
though all combustion sources should be trying to minimize metals
feedrates. However, because the alternative is metal spiking (as
evidenced in facility testing for BIF compliance) and metal spiking is
a significant concern as well, we find that the balance is better
struck by allowing, with site-specific review and where warranted
approval, extrapolation as a means to reduce unnecessary emissions,
reduce unnecessary costs incurred by facilities, and better protect the
health of testing personnel during performance tests.
iii. Conditional Waiver of Limit on Low Volatile Metals in Pumpable
Feedstreams. Commenters indicate that they may want to base feedrate
limits only on the worst-case feedstream--pumpable hazardous waste. The
feedrate limit would be based only on the feedrate of the pumpable
hazardous waste during the comprehensive performance test, even though
nonpumpable feedstreams would be contributing some metals to emissions.
In this situation, commenters suggest that separate feedrate limits for
total and pumpable feedstreams would not be needed. We agree that if
you define the total feedstream feedrate limit as the pumpable
feedstream feedrate during the performance test, dual limits are not
required. The feedrate of metals in total feedstreams must be monitored
and shown to be below the pumpable feedstream-based limit. See
Sec. 63.1209(n)(2)(C).
iv. Response to other Comments. We discuss below our response to
several other comments: (1) Recommendation for national uniform
feedrate limits; (2) concerns that feedstream monitoring is
problematic; and (3) recommendations that monitoring natural gas and
vapor recovery system feedstreams is unnecessary.
A commenter states that nationally uniform feedrate limits are
needed for metals and chlorine and that any other approach would be
inconsistent with the CAA. The commenter stated that hazardous waste
combustion device operators should not be allowed to self-select any
level of toxic metal feedrate just because they can show compliance
with the MACT standard. We believe that standards prescribing national
feedrate limits on metals or chlorine are not necessary to ensure MACT
control of metals and hydrochloric acid/chlorine gas and may be overly
restrictive. Emissions of metals and hydrochloric acid/chlorine gas are
controlled by controlling the feedrate of metals and chlorine, and
emission control devices. In developing MACT standards for a source
category, if we can identify emission levels that are being achieved by
the best performing sources using MACT control, we generally establish
the MACT standard as an emission level rather than prescribed operating
limits (e.g., feedrate limits). This approach is preferable because it
gives the source the option of determining the most cost-effective
measures to comply with the standard. Some sources may elect to comply
with the emission standards using primarily feedrate control, while
others may elect to rely primarily on emission controls. Under either
approach, the emission levels are equivalent to those being achieved by
the best performing existing sources. Other factors that we considered
in determining to express the standards as an emission level rather
than feedrate limits include: (1) There is not a single, universal
correlation factor between feedrate and metal emissions to use to
determine a national feedrate that would be equivalent to the emission
levels achieved by the best performing sources; (2) emission standards
communicate better to the public that meaningful controls are being
applied because the hazardous waste combustor

[[Page 52948]]

emission standards can be compared to standards for other waste
combustors (e.g., municipal and medical waste combustors) and
combustion devices; and (3) CEMS, the ultimate compliance assurance
tool that we encourage sources to use,²⁴³ are incompatible
with standards expressed as feedrate limits.
---------------------------------------------------------------------------

\243\ As discussed previously in the text, feedrate limits as a
compliance tool can be problematic for difficult to sample or
analyze feedstreams. Further, the emissions resulting from a given
feedrate level may increase (or decrease) over time, providing
uncertainty about actual emissions.
---------------------------------------------------------------------------

Another commenter is concerned that feedrate monitoring of highly
heterogeneous waste streams is problematic and analytical turnaround
times can be rather long. The commenter suggests that alternatives
beyond feedstream monitoring (such as predictive emissions monitoring)
should be allowed. Although we acknowledge that there may be
difficulties in monitoring the feedrate of metals or chlorine in
certain waste streams, there generally is no better way to assure
compliance with these standards other than using CEMS. Predictive
modeling appears to introduce unnecessarily some greater compliance
uncertainty than feedstream testing. Thus, we conclude that feedstream
monitoring is a necessary monitoring tool if a multimetals CEMS is not
used. (We also note that feedstream monitoring under MACT will not be
substantially more burdensome or problematic than the requirements now
in place under RCRA regulations.)
In addition, another commenter suggests that sources should not
have to monitor metals and chlorine in natural gas feedstreams because
it is impractical and levels are low and unvarying. The commenter
suggests that sources should be allowed to use characterization data
from natural gas vendors. We agree that the cost and possible hazards
of monitoring natural gas for metals and chlorine is not warranted
because our data shows metals are not present at levels of concern.
Therefore, you are not required to monitor metals and chlorine levels
in natural gas feedstreams. However, you must document in the
comprehensive performance test plan the expected levels of these
constituents and account for the expected levels in documenting
compliance with feedrate limits (e.g., by assuming worst-case
concentrations and monitoring the natural gas flowrate). See
Sec. 63.1209(c)(5).
Finally, some commenters are concerned that feedstreams from vapor
recovery systems (e.g., waste fuel tank and container emissions) are
difficult, costly, and often dangerous to monitor frequently for metals
and chlorine levels. Particularly because of some of the safety issues
concerned, the rule does not require continuous monitoring of metals
and chlorine for feedstreams from vapor recovery systems. However, as
is the case for natural gas, you must document in the comprehensive
performance test plan the expected levels of these constituents and
account for the expected levels in documenting compliance with feedrate
limits.
d. Maximum Chlorine Feedrate. As proposed, you must establish a
limit on the maximum feedrate for total chlorine (both organic and
inorganic) in all feedstreams based on the level fed during the
comprehensive performance test. A limit on maximum chlorine feedrate is
necessary because most metals are more volatile in the chlorinated
form. Thus, for example, more low volatile metals may report to the
combustion gas as a vapor than would be otherwise be entrained in the
combustion gas absent the presence of chlorine. In addition, the vapor
form of the metal is more difficult to control. Although most
semivolatile and low volatile metal species are in the particulate
phase at gas temperatures at the inlet to the particulate matter
control device, semivolatile metals that condense from the vapor phase
partition to smaller particulates and are more difficult to control
than low volatile metals that are emitted in the form of entrained,
larger particulates.
To establish and comply with the feedrate limit, you must sample
and analyze, and continuously monitor the flowrate, of all feedstreams
(including hazardous waste, raw materials, and other fuels and
additives) except natural gas, process air, and feedstreams from vapor
recovery systems for total chlorine content. As proposed, you must
establish a maximum 12-hour rolling average feedrate limit based on
operations during the comprehensive performance test as the average of
the test run averages.
Commenters suggest that chlorine feedrate limits are not needed for
sources with semivolatile and low volatile metal feedrates, when
expressed as maximum theoretical emission concentrations, less than the
emission standard. We agree. In this situation, you would be eligible
for the waiver of performance test under Sec. 63.1207(m). The
requirements of that provision (e.g., monitor and record metals
feedrates and gas flowrates to ensure that metals feedrate, expressed
as a maximum theoretical emission concentration, does not exceed the
emission standard) apply in lieu of the operating parameter limits
based on performance testing discussed above. We note, however, that
you would still need to establish a maximum feedrate limit for total
chlorine as an operating parameter limit for the hydrochloric acid/
chlorine gas emission standard (discussed below), unless you also
qualified for a waiver of that emission standard under Sec. 63.1207(m).
4. What Are the Monitoring Requirements for Carbon Monoxide and
Hydrocarbon?
You must maintain compliance with the carbon monoxide and
hydrocarbon emission standards using continuous emissions monitoring
systems (CEMS). In addition, you must use an oxygen CEMS to correct
continuously the carbon monoxide and hydrocarbon levels recorded by
their CEMS to 7 percent oxygen.
As proposed, the averaging period for carbon monoxide and
hydrocarbon CEMS is a one-hour rolling average updated each minute.
This is consistent with current RCRA requirements and commenters did
not recommend an alternative averaging period.
We also are promulgating performance specifications for carbon
monoxide, hydrocarbon, and oxygen CEMS. The carbon monoxide and oxygen
CEMS performance specifications are codified as Performance
Specification 4B in appendix B, part 60. This performance specification
is the same as the specification currently used for BIFs in appendix
IX, part 266. It also is very similar to existing appendix B, part 60
Performance Specifications 3 (for oxygen) and 4A (for carbon monoxide).
New specification 4B references many of the provisions of
Specifications 3 and 4A.
The hydrocarbon CEMS performance specification is codified as
Performance Specification 8A in appendix B, part 60. This specification
is also identical to the specification currently used for BIFs in
section 2.2 of appendix IX, part 266, with one exception. We deleted
the quality assurance section and placed it in the appendix to subpart
EEE of part 63 promulgated today to be consistent with our approach to
part 60 performance specifications.
We discuss below several issues pertaining to monitoring with these
CEMS: (1) The requirement to establish site-specific alternative span
values in some situations; (2) consequences of exceeding the span value
of the CEMS; and (3) the need to adjust the oxygen correction factor
during startup and shutdown.
a. When Are You Required to Establish Site-Specific Alternative
Span

[[Page 52949]]

Values? As proposed, if you normally operate at an oxygen correction
factor of more than 2 (e.g., a cement kiln monitoring carbon monoxide
in the by-pass duct), you must use a carbon monoxide or hydrocarbon
CEMS with a span proportionately lower than the values prescribed in
the performance specifications relative to the oxygen correction factor
at the CEMS sampling point. See the appendix to Subpart EEE, part 63:
Quality Assurance Procedures for Continuous Emissions Monitors Used for
Hazardous Waste Combustors.
This requirement arose from our experience with implementing the
BIF rule when we determined that the prescribed span values for the
carbon monoxide and hydrocarbon CEMS may lead to high error in
corrected emission values due to the effects of making the oxygen
correction. For example, a cement kiln may analyze for carbon monoxide
emissions in the by-pass duct with oxygen correction factors on the
order of 10. At the low range of the carbon monoxide CEMS span--200 ppm
as prescribed by Performance Specification 4B--with an acceptable
calibration drift of three percent, an error of 6 ppm is the result.
Accounting for the oxygen correction factor of 10, however, drives the
error in the measurement due to calibration drift up to 60 ppm. This is
more than half the carbon monoxide emission standard of 100 ppm and is
not acceptable. At carbon monoxide readings close to the 100 ppm
standard, true carbon monoxide levels may be well above or well below
the standard.
Consider the same example under today's requirement. For an oxygen
correction factor of 10, the low range span for the carbon monoxide
CEMS must be 200 divided by 10, or 20 ppm. The allowable calibration
drift of three percent of the span allows an error of 0.6 ppm at 20
ppm. Applying an oxygen correction factor of 10 results in an absolute
calibration drift error of 6ppm at an oxygen-corrected carbon monoxide
reading of 200.
b. What Are the Consequences of Exceeding the Span Value for Carbon
Monoxide and Hydrocarbon CEMS? If you do not elect to use a carbon
monoxide CEMS with a higher span value of 10,000 ppmv and a hydrocarbon
CEMS with a higher span value of 500 ppmv, you must configure your CEMS
so that a one-minute carbon monoxide value reported as 3,000 ppmv or
greater must be recorded (and used to calculate the hourly rolling
average) as 10,000 ppmv, and a one-minute hydrocarbon value reported as
200 ppmv or greater must be recorded as 500 ppmv.
If you elect to use a carbon monoxide CEMS with a span range of 0-
10,000 ppmv, you must use one or more carbon monoxide CEMS that meet
the Performance Specification 4B for three ranges: 0-200 ppmv; 1-3,000
ppmv; and 0-10,000 ppmv. Specification 4B provides requirements for the
first two ranges. For the (optional) high range of 0-10,000 ppmv, the
CEMS must also comply with Performance Specification 4B, except that
the calibration drift must be less than 300 ppmv and calibration error
must be less than 500 ppmv. These values are based on the allowable
drift and error, expressed as a percentage of span, that the
specification requires for the two lower span levels.
If you elect to use a hydrocarbon CEMS with a span range of 0-500
ppmv, you must use one or more hydrocarbon CEMS that meet Performance
Specification 8A for two ranges: 0-100 ppmv, and 0-500 ppmv.
Specification 8A provides requirements for the first range. For the
(optional) high range of 0-500 ppmv, the CEMS must also comply with
Performance Specification 8A, except: (1) The zero and high-level daily
calibration gas must be between 0 and 100 ppmv and between 250 and 450
ppmv, respectively; (2) the strip chart recorder, computer, or digital
recorder must be capable of recording all readings within the CEMS
measurement range and must have a resolution of 2.5 ppmv; (3) the CEMS
calibration must not differ by more than 15 ppmv after each
24 hour period of the seven day test at both zero and high levels; (4)
the calibration error must be no greater than 25 ppmv; and (5) the zero
level, mid-level, and high level values used to determine calibration
error must be in the range of 0-200 ppmv, 150-200 ppmv, and 350-400
ppmv, respectively. These requirements for the optional high range (0-
500 ppmv) are derived proportionately from the requirements in
Specification 8A for the lower range (0-100 ppmv).
The rule provides this requirement because we are concerned that,
when carbon monoxide and hydrocarbon monitors record a one-minute value
at the upper span level, the actual level of carbon monoxide or
hydrocarbons may be much higher (i.e., these CEMS often ``peg-out'' at
the upper span level). This has two inappropriate consequences. First,
the source may actually be exceeding the carbon monoxide or hydrocarbon
standard even though the CEMS indicates that it is not. Second, if the
carbon monoxide or hydrocarbon hourly rolling average were to exceed
the standard, triggering an automatic waste feed cutoff, the emission
level may drop back below the standard much sooner than it otherwise
would if the actual one-minute average emission levels were recorded
(i.e., rather than one-minute averages pegged at the upper span value).
Thus, this diminishes the economic disincentive for incurring automatic
waste feed cutoffs of not being able to restart the hazardous waste
feed until carbon monoxide and hydrocarbon levels are below the
standard.
We considered applying these ``out-of-span'' requirements when any
recorded value (i.e., any value recorded by the CEMS on a frequency of
at least every 15 seconds), rather than one-minute average values,
exceeded the upper span level. Commenters point out, however, that CEMS
may experience short-term electronic glitches that cause the monitored
output to spike for a very short time period. We concur, and conclude
that we should be concerned only about one-minute average values
because these short-term electronic glitches (that are not caused by
emission excursions) could result in an undesirable increase in
automatic waste feed cutoffs.
You may prefer to use carbon monoxide or hydrocarbon CEMS that have
upper span values between 3,000 and 10,000 ppmv and between 100 and 500
ppmv, respectively. If you believe that you would not have one-minute
average carbon monoxide or hydrocarbon levels as high as 10,000 ppmv
and 500 ppmv, respectively, you may determine that it would be less
expensive to use monitors with lower upper span levels (e.g., you may
be able to use a single carbon monoxide CEMS to meet performance
specifications for all three spans--the two lower spans required by
Specification 4B, and a higher span (but less than 10,000)). You must
still record, however, any one-minute average carbon monoxide or
hydrocarbon levels that are at or above the span as 10,000 ppmv and 500
ppmv, respectively.
c. How Is the Oxygen Correction Factor Adjusted during Startup and
Shutdown? You must identify in your Startup Shutdown, and Malfunction
Plan a projected oxygen correction factor to use during periods of
startup and shutdown. The projected oxygen correction factor should be
based on normal operations. See Sec. 63.1206(c)(2)(iii). The rule
provides this requirement because the oxygen concentration in the
combustor can exceed 15% during startup and shutdown, causing the
correction factor to increase exponentially from the normal value. Such
large correction factors result in corrected carbon

[[Page 52950]]

monoxide and hydrocarbon levels that are inappropriately inflated.
5. What Are the Operating Parameter Limits for Hydrochloric Acid/
Chlorine Gas?
You must maintain compliance with the hydrochloric acid/chlorine
gas emission standard by establishing and complying with limits on
operating parameters. See Sec. 63.1209(o). The following table
summarizes these operating parameter limits. All sources must comply
with the maximum chlorine feedrate limit. Other operating parameter
limits apply depending on the type of hydrochloric acid/chlorine gas
emission control device you use.

BILLING CODE 6560-50-P

[[Page 52951]]

[GRAPHIC] [TIFF OMITTED] TR30SE99.004

BILLING CODE 6560-50-C

[[Page 52952]]

Hydrochloric acid/chlorine gas emissions from hazardous waste
combustors are controlled by controlling the feedrate of total chlorine
(organic and inorganic) and either wet or dry scrubbers. We discuss
below the operating parameter limits that apply to each control
technique.
a. Maximum Chlorine Feedrate Limit. As proposed, you must establish
a limit on the maximum feedrate of chlorine, both organic and
inorganic, from all feedstreams based on levels fed during the
comprehensive performance test. Chlorine feedrate is an important
emission control technique because the amount of chlorine fed into a
combustor directly affects emissions of hydrochloric acid/chlorine gas.
To establish and comply with the feedrate limit, you must sample and
analyze, and continuously monitor the flowrate, of all feedstreams
(including hazardous waste, raw materials, and other fuels and
additives) except natural gas, process air, and feedstreams from vapor
recovery systems for chlorine content.²⁴⁴ Also as proposed,
you must establish a maximum 12-hour rolling average feedrate limit
based on operations during the comprehensive performance test as the
average of the test run averages.
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\244\ See discussion in Section VII.D.3 above in the text for
the rationale for exempting these feedstreams for monitoring for
chlorine content.
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One commenter states that a chlorine feedrate is not necessary for
cement kilns because cement kilns have an inherent incentive to control
chlorine feedrates: to avoid operational problems such as the formation
of material rings in the kiln or alkali-chloride condensation on the
walls. Although we understand that cement kilns must monitor chlorine
feedrates for operational reasons, several cement kilns in our data
base emit levels of hydrochloric acid/chlorine gas at levels above
today's emissions standard. We conclude, therefore, that the
operational incentive to limit chlorine feedrates is not adequate to
ensure compliance with the hydrochloric acid/chlorine gas emission
standard.
b. Wet Scrubbers. If your combustor is equipped with a wet
scrubber, you must establish, continuously monitor, and comply with
limits on the following operating parameters:
i. Maximum Flue Gas Flowrate or Kiln Production Rate. As proposed,
you must establish a limit on maximum flue gas flowrate or kiln
production rate as a surrogate. See 61 FR at 17433. Gas flowrate is a
key parameter affecting the control efficiency of a wet scrubber (and
any emissions control device). As gas flowrate increases, control
efficiency generally decreases unless other operating parameters are
adjusted to accommodate the increased flowrate. Cement kilns and
lightweight aggregate kilns may establish a limit on maximum production
rate (e.g., raw material feedrate or clinker or aggregate production
rate) in lieu of a maximum gas flowrate given that production rate
directly relates to flue gas flowrate.
As proposed, you must establish a maximum gas flowrate or
production rate limit as the average of the maximum hourly rolling
averages for each run of the comprehensive performance test.
We did not receive adverse comment on this compliance parameter.
ii. Minimum Pressure Drop Across the Scrubber. You must establish a
limit on minimum pressure drop across the scrubber. If your combustor
is equipped with a high energy scrubber (e.g., venturi, calvert), you
must establish an hourly rolling average limits based on operations
during the comprehensive performance test. The hourly rolling average
is established as the average of the test run averages.
If your combustor is equipped with a low energy scrubber (e.g.,
spray tower), you must establish a limit on minimum pressure drop based
on the manufacturer's specification. You must comply with the limit on
an hourly rolling average basis.
Pressure drop across a wet scrubber is an important operating
parameter because it is an indicator of good mixing of the two fluids,
the scrubber liquid and the flue gas. A low pressure drop indicates
poor mixing and, hence, poor efficiency. A high pressure drop indicates
good removal efficiency.
One commenter states that wet scrubber pressure drop is not an
important parameter for packed-bed, low energy wet scrubbers. The
commenter states that the performance of a packed-bed scrubber is based
on good liquid-to-gas contacting. Thus, performance is dependent on
packing design and scrubber fluid flow. In addition, the commenter
states that scrubber liquid flow rate (and recirculation rate and make-
up water flow rate) are adequate for assuring proper scrubber
operation. We note that for many types of low energy wet scrubbers,
pressure drop can be a rough indicator of scrubber liquid and flue gas
contacting. Thus, although it is not a critical parameter, the minimum
pressure drop of a low energy scrubber should still be monitored and
complied with on a continuous basis.
Because pressure drop for a low energy scrubber (e.g., spray
towers, packed beds, or tray towers) is not as important as for a high
energy scrubber to maintain performance, however, the rule requires you
to establish a limit on the minimum pressure drop for a low energy
scrubber based on manufacturer specifications, rather than levels
demonstrated during compliance testing. You must comply with this limit
on an hourly rolling average basis. The pressure drop for high energy
wet scrubbers, such as venturi or calvert scrubbers, however, is a key
operating parameter to ensure the scrubber maintains performance.
Accordingly, you must base the minimum pressure drop for these devices
on levels achieved during the comprehensive test, and you must
establish an hourly rolling average limit.
iii. Minimum Liquid Feed Pressure. You must establish a limit on
minimum liquid feed pressure to a low energy scrubber. The limit must
be based on manufacturer's specifications and you must comply with it
on an hourly rolling average basis.
The rule requires a limit on liquid feed pressure because the
removal efficiency of a low energy wet scrubber can be directly
affected by the atomization efficiency of the scrubber. A drop in
liquid feed pressure may be an indicator of poor atomization and poor
scrubber removal efficiency. We are not requiring a limit on minimum
liquid feed pressure for high energy scrubbers because liquid flow rate
rather than feed pressure is the dominant operating parameter for high
energy scrubbers.
We acknowledge, however, that not all wet scrubbers rely on
atomization efficiency to maintain performance. If manufacturer's
specifications indicate that atomization efficiency is not an important
parameter that controls the efficiency of your scrubber, you may
petition permitting officials under Sec. 63.1209(g)(1) to waive this
operating parameter limit.
iv. Minimum Liquid pH. You must establish dual ten-minute and
hourly rolling average limits on minimum pH of the scrubber water based
on operations during the comprehensive performance test. The hourly
rolling average is established as the average of the test run averages.
The pH of the scrubber liquid is an important operating parameter
because, at low pH, the scrubber solution is more acidic and removal
efficiency of hydrochloric acid and chlorine gas decreases.
These requirements, except for the proposed ten-minute averaging
period, are the same as we proposed. See 61 FR at 17433. We did not
receive adverse comments.

[[Page 52953]]

v. Minimum Scrubber Liquid Flowrate or Minimum Liquid/Gas Ratio.
You must establish an hourly rolling average limits on either minimum
scrubber liquid flowrate and maximum flue gas flowrate or minimum
liquid/gas ratio based on operations during the comprehensive
performance test. The hourly rolling average is established as the
average of the test run averages.
Liquid flowrate and flue gas flowrate or liquid/gas ratio are
important operating parameters because a high liquid-to-gas-flowrate
ratio is indicative of good removal efficiency.
We had proposed to limit the liquid-to-gas ratio only. Commenters
suggest that a limit on liquid-to-gas flow ratio would not be needed if
the liquid flowrate and flue gas flowrate were limited instead. They
reason that, because gas flowrate is already limited, limiting liquid
flowrate as well would ensure that the liquid-to-gas ratio is
maintained. We agree. During normal operations, the liquid flowrate can
only be higher than levels during the performance test, and gas
flowrate can only be lower than during the performance test. Thus, the
numerator in the liquid flowrate/gas flowrate ratio could only be
larger, and the denominator could only be smaller. Consequently, the
liquid flowrate/gas flowrate during normal operations will always be
higher than during the comprehensive performance test. Consequently, we
agree that a limit on liquid-to-gas-ratio is not needed if you
establish a limit on liquid flowrate and flue gas flowrate.
Establishing limits on these parameters is adequate to ensure that the
liquid flowrate/gas ratio is maintained.²⁴⁵
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\245\ In fact, complying with limits on liquid flowrate and gas
flowrate, rather than complying with a liquid flowrate/gas flowrate
ratio, is a more conservative approach to ensure that the
performance test ratio is maintained (at a minimum). Thus, we prefer
that you establish a limit on liquid flowrate (in conjunction with
the limit gas flowrate) in lieu of a limit on the ratio.
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c. Dry Scrubbers. A dry scrubber removes hydrochloric acid from the
flue gas by adsorbing the hydrochloric acid onto sorbent, normally an
alkaline substance like limestone. As proposed, if your combustor is
equipped with a dry scrubber, you must establish, continuously monitor,
and comply with limits on the following operating parameters: Gas
flowrate or kiln production rate; sorbent feedrate; carrier fluid
flowrate or nozzle pressure drop; and sorbent specifications. See 61 FR
at 17434.
i. Maximum Flue Gas Flowrate or Kiln Production Rate. As proposed,
you must establish a limit on maximum flue gas flowrate or kiln
production rate as a surrogate. The limit is established and monitored
as discussed above for wet scrubbers.
ii. Minimum Sorbent Feedrate. You must establish an hourly rolling
average limit on minimum sorbent feedrate based on feedrate levels
during the comprehensive performance test. The hourly rolling average
is established as the average of the test run averages.
Sorbent feedrate is important because, as more sorbent is fed into
the dry scrubber, removal efficiency of hydrochloric acid and chlorine
gas increases.²⁴⁶ Conversely, lower sorbent feedrates tend
to cause removal efficiency to decrease.
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\246\ We note that sorbent should be fed to a dry scrubber in
excess of the stoichiometric requirements for neutralizing the anion
component in the flue gas. Lower levels of sorbent, even above
stoichiometric requirements, would limit the removal of acid gasses.
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At proposal, we invited comment on whether a ten-minute rolling
average is appropriate for sorbent feedrate (61 FR at 17434). We were
concerned that some facilities may not automate their dry scrubbers to
add sorbent solutions but instead add batches of virgin sorbent
solution. Thus, we were concerned that a ten-minute rolling average may
not be practicable in all cases. Some commenters are concerned that a
ten-minute limit would be difficult to measure, especially in the case
of batch addition of sorbent. Nonetheless, we have determined upon
reanalysis that sorbent is not injected into the flue gas in
``batches.'' Although sorbent may be added in batches to storage or
mixing vessels, it must be injected into the flue gas continuously to
provide continuous and effective removal of acid gases. Thus, ten-
minute rolling average limits would be practicable and appropriate for
sorbent injection feedrates if ten-minute averages were required in
this final rule.²⁴⁷ However, as discussed in Part Five,
Section VII.B, we have decided to not require ten-minute averaging
periods on a national basis. Permitting officials may, however,
determine that shorter averaging periods are needed to better assure
compliance with the emission standard.
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\247\ We note that flowrate measurement devices are available
for ten-minute average times (e.g., those based on volumetric screw
feeders which provide instantaneous measurements).
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iii. Minimum Carrier Fluid Flowrate or Nozzle Pressure Drop. A
carrier fluid, normally air or water, is necessary to transport and
inject the sorbent into the gas stream. As proposed, you must establish
and continuously monitor a limit on either minimum carrier gas or water
flowrate or pressure drop across the nozzle to ensure that the flow and
dispersion of the injected sorbent into the flue gas stream is
maintained. You must base the limit on manufacturer's specifications,
and comply with the limit on a one-hour rolling average basis.
Without proper carrier flow to the dry scrubber, the sorbent flow
into the scrubber will decrease causing the efficiency to decrease.
Nozzle pressure drop is also an indicator of carrier gas flow into the
scrubber. At higher pressure drops, more sorbent is carried to the dry
scrubber.
iv. Identification of Sorbent Brand and Type or Adsorption
Properties. You must either identify the sorbent brand and type used
during the comprehensive performance test and continue using that
sorbent, or identify the adsorption properties of that sorbent and use
a sorbent having equivalent or better properties. This will ensure that
the sorbent's adsorption properties are maintained.
We proposed to require sources to continue to use the same sorbent
brand and type as they used during the comprehensive performance test
or obtain a waiver from this requirement from the Administrator. See 61
FR at 17434. As discussed above in the context of specifying the brand
of carbon used in carbon injection systems to control dioxin/furan, we
have determined that sources should have the option of using
manufacturer's specifications to specify the sorption properties of the
sorbent used during the comprehensive performance test. You may use
sorbent of other brands or types provided that it has equivalent or
better sorption properties. You must include in the operating record
written documentation that the substitute sorbent will provide the same
level of control as the original sorbent.
6. What Are the Operating Parameter Limits for Particulate Matter?
You must maintain compliance with the particulate matter emission
standard by establishing and complying with limits on operating
parameters. See Sec. 63.1209(m). The following table summarizes these
operating parameter limits. All incinerators must comply with the limit
on maximum ash feedrate. Other operating parameter limits apply
depending on the type of particulate matter control device you use.

BILLING CODE 6560-50-P

[[Page 52954]]

[GRAPHIC] [TIFF OMITTED] TR30SE99.005

BILLING CODE 6560-50-C

[[Page 52955]]

Particulate matter emissions from hazardous waste combustors are
controlled by controlling the feedrate of ash to incinerators and using
a particulate matter control device. We discuss below the operating
parameter limits that apply to each control technique.
a. Maximum Ash Feedrate. As proposed, if you own or operate an
incinerator, you must establish a limit on the maximum feedrate of ash
from all feedstreams based on the levels fed during the comprehensive
performance test. To establish and comply with the feedrate limit, you
must sample and analyze, and continuously monitor the flowrate of all
feedstreams (including hazardous waste, and other fuels and additives)
except natural gas, process air, and feedstreams from vapor recovery
systems for ash content.²⁴⁸ Also as proposed, you must
establish a maximum 12-hour rolling average feedrate limit based on
operations during the comprehensive performance test as the average of
the test run averages. See 61 FR at 17438.
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\248\ See discussion in Section VII.D.3 above in the text for
the rationale for exempting these feedstreams from monitoring for
ash content.
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Ash feedrate for incinerators is an important particulate matter
control parameter because ash feedrates can relate directly to
emissions of particulate matter (i.e., ash contributes to particulate
matter in flue gas). We are not requiring an ash feedrate limit for
cement or lightweight aggregate kilns because particulate matter from
those combustors is dominated by raw materials entrained in the flue
gas. The contribution to particulate matter of ash from hazardous waste
or other feedstreams is not significant. We discussed this issue at
proposal.
A commenter states that ash feedrate limits are not needed for
combustors using fabric filters, suggesting that fabric filter pressure
drop and opacity monitoring are sufficient for compliance assurance. We
discuss previously in this section (i.e., Part Five, Section VII) our
concern that neither opacity monitors, nor limits on control device
operating parameter, nor limits on the feedrates of constituents that
can contribute directly to emissions of hazardous air pollutants
comprise an ideal compliance assurance regime. We would prefer the use
of a particulate matter CEMS for compliance assurance but cannot
achieve that goal at this time. Absent the use of a CEMS and given the
limitations of the individual compliance tools currently available, we
are reluctant to forgo on a national, generic basis requiring limits on
an operating parameter such as ash feedrate that we know can relate
directly to particulate emissions. However, you may petition permitting
officials under Sec. 63.1209(g)(1) for approval to waive the ash
feedrate limit based on data or information documenting that pressure
drop across the fabric filter coupled with an opacity monitor would
provide equivalent or better compliance assurance than a limit on ash
feedrate.
b. Wet Scrubbers. As proposed, if your combustor is equipped with a
wet scrubber, you must establish, continuously monitor, and comply with
limits on the operating parameters discussed below. High energy wet
scrubbers (e.g., venturi, calvert) remove particulate matter by
capturing particles in liquid droplets and separating the droplets from
the gas stream. Ionizing wet scrubbers use both an electrical charge
and wet scrubbing to remove particulate matter. Low energy wet
scrubbers that are not ionizing wet scrubbers (e.g., packed bed, spray
tower) are only subject to the scrubber water solids content operating
parameter requirements for particulate matter control because they are
primarily used to control emissions of acid gases and only provide
incidental particulate matter control.
i. Maximum Flue Gas Flowrate or Kiln Production Rate. For high
energy and ionic wet scrubbers, you must establish a limit on maximum
flue gas flowrate or kiln production rate as a surrogate. See 61 FR at
17438. Gas flowrate is a key parameter affecting the control efficiency
of a wet scrubber (and any emissions control device). As gas flowrate
increases, control efficiency generally decreases unless other
operating parameters are adjusted to accommodate the increased
flowrate. Cement kilns and lightweight aggregate kilns may establish a
limit on maximum production rate (e.g., raw material feedrate or
clinker or aggregate production rate) in lieu of a maximum gas flowrate
given that production rate directly relates to flue gas flowrate.
As proposed, you must establish a maximum gas flowrate or
production rate limit as the average of the maximum hourly rolling
averages for each run of the comprehensive performance test.
ii. Minimum Pressure Drop Across the Scrubber. For high energy
scrubbers only, you must establish an hourly rolling average limits on
minimum pressure drop across the scrubber based on operations during
the comprehensive performance test. The hourly rolling average is
established as the average of the test run averages. See the discussion
in Section VII.D.5.b above for a discussion on the approach for
calculating limits from comprehensive performance test data.
iii. Minimum Scrubber Liquid Flowrate or Minimum Liquid/Gas Ratio.
For high energy wet scrubbers, you must establish an hourly rolling
average limits on either minimum scrubber liquid flowrate and maximum
flue gas flowrate or minimum liquid/gas ratio based on operations
during the comprehensive performance test. The hourly rolling average
is established as the average of the test run averages. See the
discussion in Section VII.D.5.b above for a discussion on the approach
for calculating limits from comprehensive performance test data.
iv. Maximum Solids Content of Scrubber Water or Minimum Blowdown
Rate Plus Minimum Scrubber Tank Volume or Level. For all wet scrubbers,
to maintain the solids content of the scrubber water to levels no
higher than during the comprehensive performance test, you must
establish a limit on either: (1) Maximum solids content of the scrubber
water; or (2) minimum blowdown rate plus minimum scrubber tank volume
or level. If you elect to establish a limit on maximum solids content
of the scrubber water, you must comply with the limit either by: (1)
Continuously monitoring the solids content and establishing 12-hour
rolling average limits based on solids content during the comprehensive
performance test; or (2) periodic manual sampling and analysis of
scrubber water for solids content. Under option 1, the 12-hour rolling
average is established as the average of the test run averages. Under
option 2, you must either comply with a default sampling and analysis
frequency for scrubber water solids content of once per hour or
recommend an alternative frequency in your comprehensive performance
test plan that you submit for review and approval.
Solids content in the scrubber water is an important operating
parameter because as the solids content increases, particulate
emissions increase. This is attributable to evaporation of scrubber
water and release of previously captured particulate back into the flue
gas. Blowdown is the amount of scrubber liquid removed from the process
and not recycled back into the wet scrubber. As scrubber liquid is
removed and not recycled, solids are removed. Thus, blowdown is an
operating parameter that affects solids content and can be used as a
surrogate for measuring solids content directly. See 61 FR 17438.
The proposed rule would have required continuously monitored limits
on either minimum blowdown or a

[[Page 52956]]

maximum solids content. In response to comments and upon reanalysis of
the issues, we conclude that we need to make two revisions to these
requirements. First, we are concerned that it may be problematic to
continuously monitor the solids content of scrubber water.
Consequently, we revised the requirements to allow manual sampling and
analysis on an hourly basis, unless you justify an alternative
frequency. Second, we are concerned that a limit on blowdown rate
without an associated limit on either minimum scrubber water tank
volume or level would not be adequate to provide control of solids
content. The solids concentration in blowdown tanks could be higher at
lower water levels. Therefore, water levels need to be at least
equivalent to the levels during the comprehensive performance test.
This should not be a significant additional burden. Sources should be
monitoring the water level in the scrubber water tank as a measure of
good operating practices. Consequently, we revise the requirement to
require a minimum tank volume or level in conjunction with a minimum
blowdown rate for sources that elect to use that compliance option.
c. Fabric Filter. If your combustor is equipped with a fabric
filter, you must establish, continuously monitor, and comply with
limits on the operating parameters discussed below.
i. Maximum Flue Gas Flowrate or Kiln Production Rate. As proposed,
you must establish a limit on maximum flue gas flowrate or kiln
production rate as a surrogate. Gas flowrate is a key parameter
affecting the control efficiency of a fabric filter (and any emissions
control device). As gas flowrate increases, control efficiency
generally decreases unless other operating parameters are adjusted to
accommodate the increased flowrate. Cement kilns and lightweight
aggregate kilns may establish a limit on maximum production rate (e.g.,
raw material feedrate or clinker or aggregate production rate) in lieu
of a maximum gas flowrate given that production rate directly relates
to flue gas flowrate.
As proposed, you must establish a maximum gas flowrate or
production rate limit as the average of the maximum hourly rolling
averages for each run of the comprehensive performance test.
ii. Minimum Pressure Drop and Maximum Pressure Drop Across the
Fabric Filter. You must establish a limit on minimum pressure drop and
maximum pressure drop across each cell of the fabric filter based on
manufacturer's specifications.
Filter failure is typically due to filter holes, bleed-through
migration of particulate through the filter and cake, and small ``pin
holes'' in the filter and cake. Because low pressure drop is an
indicator of one of these types of failure, pressure drop across the
fabric filter is an indicator of fabric filter failure.
We had proposed to establish limits on minimum pressure drop based
on the performance test. Commenters indicate, however, that maintaining
a pressure drop not less than levels during the performance test will
not ensure baghouse performance. We concur. The pressure change caused
by fabric holes may not be measurable, especially at large sources with
multiple chamber filter housing units that operate in parallel. In
addition, operating at high pressure drop may not be desirable because
high pressures can create pin holes.
Nonetheless, establishing a limit on minimum pressure drop based on
manufacturer's recommendations, as suggested by a commenter, is a
reasonable and prudent approach to help ensure fabric filter
performance. We have since determined that an operating parameter limit
for maximum pressure drop across each cell of the fabric filter, based
on manufacturer specifications, is also necessary. As discussed above,
a high pressure drop in a cell of a fabric filter may cause small
pinholes to form or may be indicative of bag blinding or plugging,
which could result in increased particulate emissions. We do not
consider this additional provision to be burdensome, especially because
both the maximum and minimum pressure drop limits are based on
manufacturer specifications on an hourly rolling average. These
pressure drop monitoring requirements, in combination with COMS for
cement kilns and bag leak detection systems for incinerators and
lightweight aggregate kilns, provide a significant measure of assurance
that control performance is maintained.
d. Electrostatic Precipitators and Ionizing Wet Scrubbers. As
proposed, if your combustor is equipped with an electrostatic
precipitator or ionizing wet scrubber, you must establish, continuously
monitor, and comply with limits on the operating parameters discussed
below.
i. Maximum Flue Gas Flowrate or Kiln Production Rate. You must
establish a limit on maximum flue gas flowrate or kiln production rate
as a surrogate. Gas flowrate is a key parameter affecting the control
efficiency of an emissions control device. As gas flowrate increases,
control efficiency generally decreases unless other operating
parameters are adjusted to accommodate the increased flowrate. Cement
kilns and lightweight aggregate kilns may establish a limit on maximum
production rate (e.g., raw material feedrate or clinker or aggregate
production rate) in lieu of a maximum gas flowrate given that
production rate directly relates to flue gas flowrate.
As proposed, you must establish a maximum gas flowrate or
production rate limit as the average of the maximum hourly rolling
averages for each run of the comprehensive performance test.
ii. Minimum Secondary Power Input to Each Field. You must establish
an hourly rolling average limit on minimum secondary power (kVA) input
to each field of the electrostatic precipitator or ionizing wet
scrubber based on operations during the comprehensive performance test.
The hourly rolling average is established as the average of the test
run averages.
Electrostatic precipitators capture particulate matter by charging
the particulate in an electric field and collecting the charged
particulate on an inversely charged collection plate. Higher voltages
improve magnetic field strength, resulting in charged particle
migration to the collection plate. High current leads to an increased
particle charging rate and increased electric field strength near the
collection electrode, increasing collection at the plate, as well.
Therefore, maximizing both voltage and current by specifying minimum
power input to the electrostatic precipitator is desirable for good
particulate matter collection in electrostatic precipitators. For these
reasons, the rule requires you to monitor power input to each field of
the electrostatic precipitator to ensure that collection efficiency is
maintained at performance test levels.
Power input to an ionizing wet scrubber is important because it
directly affects particulate removal. Ionizing wet scrubbers charge the
particulate prior to it entering a packed bed wet scrubber. The
charging aids in the collection of the particulate onto the packing
surface in the bed. The particulate is then washed off the packing by
the scrubber liquid. Therefore, power input is a key parameter to
proper operation of an ionizing wet scrubber.
One commenter suggests that a minimum limit on electrostatic
precipitator voltage be used instead of power input because, at low
particulate matter loadings, operation at maximum power input is
inefficient. Another commenter suggests that neither a limit on voltage
or power input is appropriate because a minimum limit would

[[Page 52957]]

actually cause a potential decrease in operational efficiency (required
power input and voltage are strong functions of gas and particulate
characteristics, electrostatic precipitator arcing and sparking at high
voltage and power requirements, etc.). Alternatively, they recommend
that a limit on the minimum number of energized electrostatic
precipitator fields be established. We continue to maintain that a
minimum limit on power input to each field of the electrostatic
precipitator is generally accepted as an appropriate parameter for
assuring electrostatic precipitator performance. Consequently, it is an
appropriate parameter for a generic, national standard. If you believe,
however, that in your situation limits on alternative operating
parameters may better assure that control performance is maintained you
may request approval to use alternative monitoring approaches under
Sec. 63.1209(1).
Another commenter suggests that, in addition to a minimum power
input for an ionizing wet scrubber, a limit should be set on the
maximum time allowable to be below the minimum voltage. While feasible,
we conclude that this limit is not necessary on a national basis
because the one hour rolling average requirement limits the amount of
time a source can operate below its minimum voltage limit. We
acknowledge, however, that a permit writer may find it necessary to
require shorter averaging periods (e.g., ten-minute or instantaneous
limits) to better control the amount of time a source can operate at
levels below its limit.
7. What Are the Operating Parameter Limits for Destruction and Removal
Efficiency?
You must establish, monitor, and comply with the same operating
parameter limits to ensure compliance with the destruction and removal
efficiency (DRE) standard as you establish to ensure good combustion
practices are maintained for compliance with the dioxin/furan emission
standard. See Sec. 63.1209(j) and the discussion in Section VII.D.1
above. This is because compliance with the DRE standard is ensured by
maintaining combustion efficiency using good combustion practices.
Thus, the DRE operating parameters are: maximum waste feedrate for
pumpable and nonpumpable wastes, minimum gas temperature for each
combustion chamber, maximum gas flowrate or kiln production rate, and
parameters that you recommend to ensure the operations of each
hazardous waste firing system are maintained.²⁴⁹
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\249\ You are required to establish operating requirements only
for hazardous waste firing systems because of DRE standard applies
only to hazardous waste. Permitting officials may determine on a
site-specific basis under authority of Sec. 63.1209(g)(2), however,
that combustion of other fuels or wastes may affect your ability to
maintain DRE for hazardous waste. Accordingly, permitting officials
may define operating requirements for other (i.e., other than
hazardous waste) waste or fuel firing systems. Permitting officials
may also determine under that provision on a site-specific basis
that operating requirements other than those prescribed for DRE (and
good combustion practices) may be needed to ensure compliance with
the DRE standard.
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VIII. Which Methods Should Be Used for Manual Stack Tests and
Feedstream Sampling and Analysis?

This part discusses the manual stack test and the feedstream
sampling and analysis methods required by today's rule.
A. Manual Stack Sampling Test Methods
To demonstrate compliance with today's rule, you must use: (1)
Method 0023A for dioxin and furans; (2) Method 29 for mercury,
semivolatile metals, and low volatile metals; (3) Method 26A for
hydrochloric acid and chlorine; and (4) Method 5 or 5i for particulate
matter. These methods are found at 40 CFR part 60, appendix A, and in
``Test Methods for Evaluating Solid Waste, Physical/Chemical Methods,''
EPA publication.
In the NPRM, we proposed that BIF manual stack test methods
currently located in SW-846 be required to demonstrate compliance with
the proposed standards. Based on public comments from the proposal, in
the December 1997 NODA we considered simply citing the ``Air Methods''
found in appendix A to part 60. Our rationale was that facilities may
be required to perform two identical tests, one from SW-846 for
compliance with MACT or RCRA and one from part 60, appendix A, for
compliance with other air rules using identical test methods simply
because one method is an SW-846 method and the other an Air Method. See
62 FR at 67803. To facilitate compliance with all air emissions stack
tests, we stated that we would list the methods found in 40 CFR part
60, appendix A, as the stack test methods used to comply with the
standards. Later in this section we present an exception for dioxin and
furan testing.
In today's rule, we adopt the approach of the December 1997 NODA
and require that the test methods found in 40 CFR part 60, appendix A
be used to demonstrate compliance with the emission standards of
today's rule, except for dioxin and furan. Specifically, today's rule
requires you to use Method 0023A in SW-846 for sampling dioxins and
furans from stack emissions. As noted by commenters, improvements have
been made to the dioxin and furan Method 0023A in the Third Update of
SW-846 that have been previously incorporated into today's regulations.
See the 40 CFR 63.1208(a), incorporation of SW-846 by reference.
However, these have not yet been incorporated into 40 CFR part 60,
Appendix A. To capture these improvements to the method, today's rule
incorporates by reference SW-846 Method 0023A. We have evaluated both
methods. Use of the improved Method 0023A will not affect the
achievability of the dioxin and furan standard.
In the proposal, we sought comment on the handling of nondetect
values for congeners analyzed using the dioxin and furan method. We
also sought comment on whether the final rule should specify minimum
sampling times. We proposed allowing facilities to assume that
emissions of dioxins and furans congeners are zero if the analysis
showed a nondetect for that congener and the sample time for the test
method run was at least 3 hours. See 61 FR 17378. Dioxin/furan results
may not be blank corrected. We received several comments this proposed
approach, which are summarized below.
One commenter believes that a minimum dioxin/furan sampling time of
two hours is sufficient. Another commenter believes that a minimum
sample time as well as a minimum sample volume should be specified.
Several commenters agree that nondetects should be treated as zero
(which is consistent with the German standard) and prefer the three
hour minimum sample period because this would help eliminate intra-
laboratory differences and difficulties with matrix effects in
attaining low detection limits. One commenter believes that EPA should
specify the required detection limit for each congener analysis,
otherwise the provision to assign zeroes to nondetected congeners in
the TEQ calculation is open to abuse and could result in an
understatement of the true dioxin/furan emissions. This commenter also
believes that a source should not be allowed to sample dioxin/furans
for time periods less than three hours, even if they assume nondetects
are present at the detection limit.
Upon carefully considering all the above comments, we conclude that
the following approach best addresses the nondetect issue. The final
rule requires all sources to sample dioxin/furans for a minimum of
three hours for each run,

[[Page 52958]]

and requires all sources to collect a flue gas sample of at least 2.5
dscm. We conclude both these requirements are necessary to maintain
consistency from source to source, and to better assure that the
dioxin/furan emission results are accurate and representative. We
conclude that these two requirements are achievable and appropriate
²⁵⁰. These requirements are consistent with the requirements
included in the proposed Portland Cement Kiln MACT rule (see 64 FR at
31898). The final rule also allows a source to assume all nondetected
congeners are not present in the emissions when calculating TEQ values
for compliance purposes.
---------------------------------------------------------------------------

\250\ See Final Technical Support Document, Volume IV, Chapter
3, for further discussion.
---------------------------------------------------------------------------

We considered whether it would be appropriate to specify required
minimum detection limits for each congener analysis in order to better
assure that sources achieved reasonable detection limits, as one
commenter recommended. Such a requirement would prevent abuse and
understatements of the true dioxin/furan emissions. We conclude,
however, that it is not appropriate to finalize minimum detection
limits in this rulemaking without giving the opportunity to all
interested parties to review and comment on such an approach.
However, we are concerned that (1) sources have no incentive to
achieve low detection limits; and (2) sources may abuse the provision
that allows nondetected congener results to be treated as if they were
not present. As explained in the Final Technical Support Document
referenced in the preceding paragraph, if one assumes that all dioxin/
furan congeners are present at what we consider to be poor detection
limits using Method 23A, the resultant TEQ can approach the emission
standard. This outcome is clearly inappropriate from a compliance
perspective.
As a result, we highly recommend that this issue be addressed in
the review process of the performance test workplan. Facilities should
submit information that describes the target detection limits for all
congeners, and calculate a dioxin/furan TEQ concentration assuming all
congeners are present at the detection limit (similar to what is done
for risk assessments). If this value is close to the emission standard,
both the source and the regulatory official should determine if it is
appropriate to either sample for longer time periods or investigate
whether it is possible to achieve lower detection limits by using
different analytical procedures that are approved by the Agency.
Also, EPA has developed analytical standards for certain mono-
through tri-chloro dioxin and furan congeners. We encourage you to test
for these congeners in addition to the congeners that comprise today's
standards. This can be done at very little increased cost. If you test
for these additional congeners, please include the results in your
Notification of Compliance. We would like this data so we can develop a
database from which to determine which (if any) of these compounds can
act as surrogate(s) for the dioxin and furan congeners which comprise
the total and TEQ. If easily measurable surrogate(s) can be found, we
can then start the development of a CEMS for these surrogates. A
complete list of these congeners will be included in the implementation
document for this rule and updated periodically through guidance.
One commenter suggests that a source be allowed to conduct one
extended dioxin/furan sampling event as opposed to three separate runs
with three separate sampling trains because this would minimize the
radioactive waste generated for sources that combust mixed waste. We
conclude this issue should be handled on a site-specific basis,
although an allowance of such an approach seems reasonable. A source
can petition the Agency under the provisions of Sec. 63.7(f) for an
alternative test method for such a site-specific determination.
The final rule also adopts the approach discussed in the December
1997 NODA for sampling of mercury, semi-volatile metals, and low-
volatile metals. Therefore, for stack sampling of mercury, semi-
volatile metals, and low-volatile metals, you are required to use
Method 29 in 40 CFR part 60, appendix A. No adverse comments were
received concerning this approach in the December 1997 NODA.
For compliance with the hydrochloric acid and chlorine standards,
today's rule requires that you use Method 26A in 40 CFR part 60,
appendix A. Commenters state that we should instead require a method
involving the Fourier Transform Infrared and Gas Filter Correlation
Infrared instrumental techniques. Commenters contend that Method 26A is
biased high at cement kilns because it collects ammonium chloride in
addition to the hydrochloric acid and chlorine gas emissions it was
designed to report. Commenters also indicate that the Fourier Transform
Infrared and Gas Filter Correlation Infrared were validated against
Method 26A and that these alternative methods do not bias the results
high due to ammonium chloride ²⁵¹. The data for today's
hydrochloric acid standard was derived using the SW-846 equivalent to
Method 26A (Method 0050) as the reference method. Therefore, today's
standard accounts for the ammonium chloride collection bias. We reject
the idea that we should require other methods. If the commenters are
correct, other methods would not sample the ammonium chloride portion,
thus making the standard less stringent. You can obtain Administrator
approval for using Fourier Transform Infrared or Gas Filter Correlation
Infrared techniques following the provisions found in 40 CFR 63.7 if
those methods are found to pass a part 63, appendix A, Method 301
validation at the source.
---------------------------------------------------------------------------

\251\ After further review and consideration of the GFCIR Method
(322), we will not be promulgating its use in the Portland Cement
Kiln NESHAP rulemaking due to problems encountered with the method
during emission testing at lime manufacturing plants.
---------------------------------------------------------------------------

Compliance with the particulate matter standards requires the use
of either Method 5 or Method 5i in 40 CFR part 60, appendix A. See a
related discussion of Method 5i in Part 5, section VII.C.2.a of the
preamble to today's rule. Although Method 5i has better precision than
Method 5, your choice of methods depends on the emissions during the
performance test. In cases of low levels of particulate matter (i.e.,
for total train catches of less than 50 mg), we prefer that Method 5i
be used. For higher emissions, Method 5 may be used ²⁵². In
practice this will likely mean that all incinerators and most
lightweight aggregate kilns will use Method 5i for compliance, while
some lightweight aggregate kilns and most cement kilns will use Method
5.
---------------------------------------------------------------------------

\252\ We note that this total train catch is not intended to be
a data acceptance criteria. Thus, total train catches exceeding 50
mg do not invalidate the method.
---------------------------------------------------------------------------

Today's rule also allows the use of any applicable SW-846 test
methods to demonstrate compliance with requirements of this subpart. As
an example, some commenters noted a preference to perform particulate
matter and hydrochloric acid tests together using Method 0050. Today's
rule would allow that practice. Applicable SW-846 test methods are
incorporated for use into today's rule via reference. See section
1208(a).
B. Sampling and Analysis of Feedstreams
Today's rule does not require the use of SW-846 methods for the
sampling and analysis of feedstreams. Consistent with our approach to
move toward performance based measurement

[[Page 52959]]

systems for other than method-defined parameters,²⁵³
today's rule allows the use of any reliable analytical method to
determine feedstream concentrations of metals, halogens, and other
constituents. It is your responsibility to ensure that the sampling and
analysis are unbiased, precise, and representative of the waste. For
the waste, you must demonstrate that: (1) Each constituent of concern
is not present above the specification level at the 80% upper
confidence limit around the mean; and (2) the analysis could have
detected the presence of the constituent at or below the specification
level at the 80% upper confidence limit around the mean. You can refer
to the Guidance for Data Quality Assessment--Practical Methods for Data
Analysis, EPA QA/G-9, January 1998, EPA/600/R-96/084 for more
information. Proper selection of an appropriate analytical method and
analytical conditions (as allowed by the scope of that method) are
demonstrated by adequate recovery of spiked analytes (or surrogate
analytes) and reproducible results. Quality control data obtained must
also reflect consistency with the data quality objectives and intent of
the analysis. You can read the January 31, 1996, memorandum from Barnes
Johnson, Director of the Economics, Methods, and Risk Assessment
Division, to James Berlow, Director of the Hazardous Waste Minimization
and Management Division for more information on this topic.
---------------------------------------------------------------------------

\253\ Feedstream sampling and analysis are not method defined
parameters.
---------------------------------------------------------------------------

IX. What Are the Reporting and Recordkeeping Requirements?

We discuss in this section reporting and recordkeeping requirements
and a provision in the rule for allowing data compression to reduce the
recordkeeping burden.
A. What Are the Reporting Requirements?
The reporting requirements of the rule include notifications and
reports that must be submitted to the Administrator as well as
notifications, requests, petitions, and applications that you must
submit to the Administrator only if you elect to request approval to
comply with certain reduced or alternative requirements. These
reporting requirements are summarized in the following tables. We
discuss previously in various sections of today's preamble the
rationale for additional or revised reporting requirements to those
currently required under subpart A of part 63 for all MACT sources. In
other cases, the reporting requirements for hazardous waste combustors
are the same as for other MACT sources (e.g., initial notification
under existing Sec. 63.9(b). We also show in the tables the
reference(s) in the regulations for the reporting requirement.

Summary of Notifications That You Must Submit to the Administrator
------------------------------------------------------------------------
Reference Notification
------------------------------------------------------------------------
63.9(b)................................ Initial notifications that you
are subject to Subpart EEE.
63.1210(b) and (c)..................... Notification of intent to
comply.
63.9(d)................................ Notification that you are
subject to special compliance
requirements.
63.1207(e), 63.9(e) 63.9(g) (1) and (3) Notification of performance
test and continuous monitoring
system evaluation, including
the performance test plan and
CMS performance evaluation
plan.
163.1210(d), 63.1207(j), 63.9(h), Notification of compliance,
63.10(d)(2), 63.10(e)(2). including results of
performance tests and
continuous monitoring system
performance evaluations.
63.1206(b)(6).......................... Notification of changes in
design, operation, or
maintenance.
63.9(j)................................ Notification and documentation
of any change in information
already provided under Sec.
63.9.
------------------------------------------------------------------------
\1\ You may also be required on a case-by-case basis to submit a
feedstream analysis plan under Sec. 63.1209(c)(3).

Summary of Reports That You Must Submit to the Administrator
------------------------------------------------------------------------
Reference Report
------------------------------------------------------------------------
63.1211(b)............................. Compliance progress report
associated and submitted with
the notification of intent to
comply.
63.10(d)(4)............................ Compliance progress reports, if
required as a condition of an
extension of the compliance
date granted under Sec.
63.6(i).
63.1206(c)(3)(vi)...................... Excessive exceedances reports.
63.1206(c)(4)(iv)...................... Emergency safety vent opening
reports.
63.10(d)(5)(i)......................... Periodic startup, shutdown, and
malfunction reports.
63.10(d)(5)(ii)........................ Immediate startup, shutdown,
and malfunction reports.
63.10(e)(3)............................ Excessive emissions and
continuous monitoring system
performance report and summary
report.
------------------------------------------------------------------------

Summary of Notifications, Requests, Petitions, and Applications That You
Must Submit to the Administrator Only if You Elect To Comply With
Reduced or Alternative Requirements
------------------------------------------------------------------------
Notification, request,
Reference petition, or application
------------------------------------------------------------------------
63.1206(b)(5), 63.1213, 63.6(i), You may request an extension of
63.9(c). the compliance date for up to
one year.
63.9(i)................................ You may request an adjustment
to time periods or postmark
deadlines for submittal and
review of required
information.
63.1209(g)(1).......................... You may request approval of:
(1) alternative monitoring
methods, except for standards
that you must monitor with a
continuous emission monitoring
system (CEMS) and except for
requests to use a CEMS in lieu
of operating parameter limits;
or (2) a waiver of an
operating parameter limit.
63.1209(a)(5), 63.8(f)................. You may request: (1) approval
of alternative monitoring
methods for compliance with
standards that are monitored
with a CEMS; and (2) approval
to use a CEMS in lieu of
operating parameter limits.

[[Page 52960]]

63.1204(d)(4).......................... Notification that you elect to
comply with the emission
averaging requirements for
cement kilns with in-line raw
mills.
63.1204(e)(4).......................... Notification that you elect to
comply with the emission
averaging requirements for
preheater or preheater/
precalciner kilns with dual
stacks.
63.1206(b)(1)(ii)(A)................... Notification that you elect to
document compliance with all
applicable requirements and
standards promulgated under
authority of the Clean Air
Act, including Sections 112
and 129, in lieu of the
requirements of Subpart EEE
when not burning hazardous
waste.
63.1206(b)(9)(iii)(B).................. If you elect to conduct
particulate matter CEMS
correlation testing and wish
to have federal particulate
matter and opacity standards
and associated operating
limits waived during the
testing, you must notify the
Administrator by submitting
the correlation test plan for
review and approval.
63.1206(b)(10)......................... Owners and operators of
lightweight aggregate kilns
may request approval of
alternative emission standards
for mercury, semivolatile
metal, low volatile metal, and
hydrochloric acid/chlorine gas
under certain conditions.
63.1206(b)(11)......................... Owners and operators of cement
kilns may request approval of
alternative emission standards
for mercury, semivolatile
metal, low volatile metal, and
hydrochloric acid/chlorine gas
under certain conditions.
63.1207(c)(2).......................... You may request to base initial
compliance on data in lieu of
a comprehensive performance
test.
63.1207(i)............................. You may request up to a one-
year time extension for
conducting a performance test
(other than the initial
comprehensive performance
test) to consolidate testing
with other state or federally-
required testing.
63.1209(l)(1).......................... You may request to extrapolate
mercury feedrate limits.
63.1209(n)(2)(ii)...................... You may request to extrapolate
semivolatile and low volatile
metal feedrate limits.
63.10(e)(3)(ii)........................ You may request to reduce the
frequency of excess emissions
and CMS performance reports.
63.10(f)............................... You may request to waive
recordkeeping or reporting
requirements.
63.1211(e)............................. You may request to use data
compression techniques to
record data on a less frequent
basis than required by Sec.
63.1209.
------------------------------------------------------------------------

Some commenters suggest that the rule needs to provide additional
reporting of information regarding metals fed to cement kilns,
including quarterly reporting of daily average metal feedrates, maximum
hourly feedrates, and all testing and analytical information on the
toxic metal content of cement kiln dust and clinker product. Also, they
suggest that toxic metals that are Toxics Release Inventory pollutants
and that are released to the land from cement kiln dust disposal should
be reported. While these reports might have some value for other
purposes, we must carefully scrutinize all reporting and recordkeeping
burdens for a rulemaking and determine whether the reporting and
recordkeeping requirements are necessary to ensure compliance with the
standards. (We, as an agency, cannot increase overall our reporting and
recordkeeping burden.)
We do not believe that these reports are needed to ensure
compliance with the standards and therefore are not requiring them. On
balance, quarterly filing requirements would be too burdensome. A
source must document compliance with all operating parameter limits and
emission standards at all times, and its records are subject to
inspection at any time. There is no additional need to provide
quarterly reports.
One commenter suggests that the proposed rule incorrectly focuses
on maximizing data collection as opposed to ensuring performance, thus
frustrating the use of better technology and methods. We, of course,
are also interested in ensuring performance by all reasonable means,
which for example accounts for our continued focus on continuous
emission monitors. However, we are not able to sacrifice data
collection as a means for ensuring compliance as well as a means to
undergird future rulemakings, assess achievability, and determine site-
specific compliance limits, where necessary.
B. What Are the Recordkeeping Requirements?
You must keep the records summarized in the table below for at
least five years from the date of each occurrence, measurement,
maintenance, corrective action, report, or record. See existing
Sec. 63.10(b)(1). At a minimum, you must retain the most recent two
years of data on site. You may retain the remaining three years of data
off site. You may maintain such files on: microfilm, a computer,
computer floppy disks, optical disk, magnetic tape, or microfiche.
We discuss previously in various sections of today's preamble the
rationale for additional or revised recordkeeping requirements to those
currently required under subpart A of part 63 for all MACT sources. In
other cases, the recordkeeping requirements for hazardous waste
combustors are the same as for other MACT sources (e.g., record of the
occurrence and duration of each malfunction of the air pollution
control equipment; see existing Sec. 63.10(b)(2)(ii)). We also show in
the table the reference(s) in the regulations for the recordkeeping
requirement.

[[Page 52961]]

Summary of Documents, Data, and Information That You Must Include in the
Operating Record
------------------------------------------------------------------------
Reference Document, data, or information
------------------------------------------------------------------------
63.1201(a), 63.10 (b) and (c).......... General. Information required
to document and maintain
compliance with the
regulations of Subpart EEE,
including data recorded by
continuous monitoring systems
(CMS), and copies of all
notifications, reports, plans,
and other documents submitted
to the Administrator.
63.1211(d)............................. Documentation of compliance.
63.1206 (c)(3)(vii).................... Documentation and results of
the automatic waste feed
cutoff operability testing.
63.1209 (c)(2)......................... Feedstream analysis plan.
63.1204 (d)(3)......................... Documentation of compliance
with the emission averaging
requirements for cement kilns
with in-line raw mills.
63.1204 (e)(3)......................... Documentation of compliance
with the emission averaging
requirements for preheater or
preheater/precalciner kilns
with dual stacks.
63.1206(b)(1) (ii)(B).................. If you elect to comply with all
applicable requirements and
standards promulgated under
authority of the Clean Air
Act, including Sections 112
and 129, in lieu of the
requirements of Subpart EEE
when not burning hazardous
waste, you must document in
the operating record that you
are in compliance with those
requirements.
63.1206 (c)(2)......................... Startup, shutdown, and
malfunction plan.
63.1206(c) (3)(v)...................... Corrective measures for any
automatic waste feed cutoff
that results in an exceedance
of an emission standard or
operating parameter limit.
63.1206(c) (4)(ii)..................... Emergency safety vent operating
plan.
63.1206 (c)(4)(iii).................... Corrective measures for any
emergency safety vent opening.
63.1206 (c)(6)......................... Operator training and
certification program.
63.1209 (k)(6)(iii), 63.1209 Documentation that a substitute
(k)(7)(ii), 63.1209 (k)(9)(ii), activated carbon, dioxin/furan
63.1209 (o)(4)(iii). formation reaction inhibitor,
or dry scrubber sorbent will
provide the same level of
control as the original
material.
------------------------------------------------------------------------

Some commenters are concerned that the specification of media on
which these files may be maintained unnecessarily limits the options to
facilities, especially those not equipped with computer or other
electronic data gathering equipment. We conclude, however, that the
options listed under Sec. 63.10(b)(1) seem to provide the greatest
flexibility possible, including the reasonable management of paper
records through the use of microfilm or microfiche. We encourage the
use of computer and electronic equipment, however, for logistical
reasons (retrieval and inspection can be easier) and as a means to
enhance dissemination to the local community to foster an atmosphere of
full and open disclosure about facility operations.
C. How Can You Receive Approval to Use Data Compression Techniques?
You may submit a written request to the Administrator under
Sec. 63.1211(f) for approval to use data compression techniques to
record data from CMS, including CEMS, on a frequency less than that
required by Sec. 63.1209. You must submit the request for review and
approval as part of the comprehensive performance test plan. For each
CEMS or operating parameter for which you request to use data
compression techniques, you must provide: (1) A fluctuation limit that
defines the maximum permissible deviation of a new data value from a
previously generated value without requiring you to revert to recording
each one-minute average; and (2) a data compression limit defined as
the closest level to an operating parameter limit or emission standard
at which reduced recording is allowed.
You must record one-minute average values at least every ten
minutes. If after exceeding a fluctuation limit you remain below the
limit for a ten-minute period, you may reinitiate your data compression
technique provided that you are not exceeding the data compression
limit.
The fluctuation limit should represent a significant change in the
parameter measured, considering the range of normal values. The data
compression limit should reflect a level at which you are unlikely to
exceed the specific operating parameter limit or emission standard,
considering its averaging period, with the addition of a new one-minute
average.
We provide the following table of recommended fluctuation and data
compression limits as guidance. These are the same limits that we
discussed in the May 1997 NODA.

Recommended Fluctuation and Data Compression Limits
----------------------------------------------------------------------------------------------------------------
Fluctuation limit () Data compression limit
----------------------------------------------------------------------------------------------------------------
Continuous Emission Monitoring System:
Carbon monoxide........................ 10 ppm....................... 50 ppm.
Hydrocarbon............................ 2 ppm........................ 60% of standard.
Combustion Gas Temperature Quench: Maximum 10 deg.F..................... Operating parameter limit (OPL)
inlet temperature for dry particulate minus 30 deg.F.
matter control device or, for lightweight
aggregate kilns, temperature at kiln exit.
Good Combustion Practices:
Maximum gas flowrate or kiln production 10% of OPL................... 60% of OPL.
rate.
Maximum hazardous waste feedrate....... 10% of OPL................... 60% of OPL.
Maximum gas temperature for each 20 deg.F..................... OPL plus 50 deg.F.
combustion chamber.
Activated Carbon Injection:
Minimum carbon injection feedrate...... 5% of OPL.................... OPL plus 20%.
Minimum carrier fluid flowrate or 20% of OPL................... OPL plus 25%.
nozzle pressure drop.
Activated Carbon Bed: Maximum gas 10 deg.F..................... OPL minus 30 deg.F.
temperature at inlet or exit of the bed.
Catalytic Oxidizer:
Minimum flue gas temperature at 20 deg.F..................... OPL plus 40 deg.F.
entrance.
Maximum flue gas temperature at 20 deg.F..................... OPL minus 40 deg.F.
entrance.
Dioxin Inhibitor: Minimum inhibitor 10% of OPL................... 60% of OPL.
feedrate.
Feedrate Control:

[[Page 52962]]

Maximum total metals feedrate (all 10% of OPL................... 60% of OPL.
feedstreams).
Maximum low volatile metals feedrate, 10% of OPL................... 60% of OPL.
pumpable feedstreams.
Maximum total ash feedrate (all 10% of OPL................... 60% of OPL.
feedstreams).
Maximum total chlorine feedrate (all 10% of OPL................... 60% of OPL.
feedstreams).
Wet scrubber:
Minimum pressure drop across scrubber.. 0.5 inches water............. OPL plus 2 inches water.
Minimum liquid feed pressure........... 20% of OPL................... OPL plus 25%.
Minimum liquid pH...................... 0.5 pH unit.................. OPL plus 1 pH unit.
Maximum solids content in liquid....... 5% of OPL.................... OPL minus 20%.
Minimum blowdown (liquid flowrate)..... 5% of OPL.................... OPL plus 20%.
Minimum liquid flowrate or liquid 10% of OPL................... OPL plus 30%.
flowrate/gas flowrate ratio.
Dry scrubber:
Minimum sorbent feedrate............... 10% of OPL................... OPL plus 30%.
Minimum carrier fluid flowrate or 10% of OPL................... OPL plus 30%.
nozzle pressure drop.
Fabric filter: Minimum pressure drop across 1 inch water................. OPL plus 2 inches water.
device.
Electrostatic precipitator and ionizing wet 5% of OPL.................... OPL plus 20%.
scrubber: Minimum power input (kVA:
current and voltage).
----------------------------------------------------------------------------------------------------------------

Data compression is the process by which a facility automatically
evaluates whether a specific data point needs to be recorded. Data
compression does not represent a change in the continuous monitoring
requirement in the rule. One-minute averages will continue to be
generated. With data compression, however, each one-minute average is
automatically compared with a set of specifications (i.e., fluctuation
limit and data compression limit) to determine whether it must be
recorded. New data are recorded when the one-minute average value falls
outside these specifications.
We did not propose data compression techniques in the April 1996
NPRM. In response to the proposed monitoring and recording
requirements, however, commenters raise concerns about the burden of
recording one-minute average values for the array of operating
parameter limits that we proposed. Commenters suggest that allowing
data compression would significantly reduce the recordkeeping burden
while maintaining the integrity of the data for compliance monitoring.
We note that data compression should also benefit regulatory officials
by allowing them to focus their review on those data that are
indicative of nonsteady-state operations and that are close to the
operating parameter limit or, for CEMS, the emission standard.
In response to these concerns, we presented data compression
specifications in the May 1997 NODA. Public comments on the NODA are
uniformly favorable. Therefore, we are including a provision in the
final rule that allows you to request approval to use data compression
techniques. The fluctuation and data compression limits presented above
are offered as guidance to assist you in developing your recommended
data compression methodology.
We are not promulgating data compression specifications because the
dynamics of monitored parameters are not uniform across the regulated
universe. Thus, establishing national specifications would be
problematic. Various data compression techniques can be successfully
implemented for a monitored parameter to obtain compressed data that
reflect the performance on a site-specific basis. Thus, the rule
requires you to recommend a data compression approach that addresses
the specifics of your operations. The fluctuation and data compression
limits presented above are offered solely as guidance and are not
required.
The rule requires that you record a value at least once every ten
minutes to ensure that a minimum, credible data base is available for
compliance monitoring. If you operate under steady-state conditions at
levels well below operating parameter limits and CEMS-monitored
emission standards, data compression techniques may enable you to
achieve a potential reduction in data recording up to 90 percent.

X. What Special Provisions Are Included in Today's Rule?

A. What Are the Alternative Standards for Cement Kilns and Lightweight
Aggregate Kilns?
In the May 1997 NODA, we discussed alternative standards for cement
kilns and lightweight aggregate kilns that have metal or chlorine
concentrations in their mineral and related process raw materials that
might cause an exceedance of today's standard(s), even though the
source uses MACT control. (See 62 FR 24238.) After carefully
considering commenters input, we adopt a process that allows sources to
petition the Administrator for alternative mercury, semivolatile metal,
low volatile metal, or hydrochloric acid/chlorine gas standards under
two different sets of circumstances. One reason for a source to
consider a petition is when a kiln cannot achieve the standard, while
using MACT control, because of raw material contributions to their
hazardous air pollutant emissions. The second reason is limited to
mercury, and applies when mercury is not present at detectable levels
in the source's raw material. These alternative standards are discussed
separately below.
1. What Are the Alternative Standards When Raw Materials Cause an
Exceedance of an Emission Standard? See sections 1206(b) (10) and (11)
a. What Approaches Have We Publicly Discussed? We acknowledge that
a kiln using properly designed and operated MACT control technologies,
including control of metals levels in hazardous waste feedstocks, may
not be capable of achieving the emission standards (i.e., the mercury,
semivolatile metal, low volatile metal, and/or hydrochloric acid/
chlorine gas standards). This can occur when hazardous air pollutants
(i.e., metals and chlorine) contained in the raw material volatilize or
are entrained in the flue gas such that their contribution to total
metal and chlorine emissions cause an exceedance of the emission
standard.
Our proposal first acknowledged this possible situation. In the
April 1996 NPRM, we proposed metal and chlorine standards that were
based, in part, on specified levels of hazardous waste feedrate control
as MACT control. To address our concern that kilns may not

[[Page 52963]]

be able to achieve the standards when using MACT control technologies,
given raw material contributions to emissions, we performed an
analysis. Our analysis estimated the total emissions of each kiln
including emissions from raw materials, while also assuming the source
was using MACT hazardous waste feedrate and particulate matter control.
Results of this analysis, which were discussed in the proposal,
indicated that there may be several kilns that would not be able to
achieve the proposed emission standards while using MACT control, due
to levels of metals and chlorine in raw material and/or conventional
fuel. (See 61 FR at 17393-17406.) Commenters requested that we provide
an equivalency determination to allow sources to comply with a control
efficiency requirement (e.g., a minimum metal system removal
efficiency) in lieu of the emission standard. (See response below.)
In the May 1997 NODA, we discussed revised standards that defined
MACT control, in part, based on hazardous waste metal and chlorine
feedrate control--as did the NPRM. (See 62 FR 24225-24235.) However,
our revised approach did not define specific levels of hazardous waste
metal and chlorine feedrate control, therefore, making it difficult to
attribute a kiln's failure to meet emission standards to metals levels
in raw materials.²⁵⁴ In response to a commenter's request,
we discussed, in the May 1997 NODA, an alternative approach to address
raw material contributions. Our approach did not subject a source to
the MACT standards if the source could document that metal or chlorine
concentrations in their hazardous waste, and any nonmineral feedstock,
is within the range of normal industry levels. The purpose of this
requirement was to ensure that metal and chlorine emissions
attributable to nonmineral feedstreams were roughly equivalent to those
from sources achieving the MACT emission standards. The use of an
industry average, or normal metal and chlorine level, was to serve as a
surrogate MACT feedrate control level for the alternative standard
because we did not define a specific level of control as MACT. We also
requested comment on how best to determine normal hazardous waste metal
and chlorine levels.
---------------------------------------------------------------------------

\254\ We could not estimate a cement kiln's total emissions
(i.e., to determine emission standard achievability) based on the
assumption that the kiln is feeding metals in the hazardous waste at
the MACT control feedrate levels.
---------------------------------------------------------------------------

Today's final rule uses a revised standard setting methodology that
defines specific levels of hazardous waste metal and chlorine feedrates
as MACT control.²⁵⁵ As a result, we do not need to define
normal, or average, metal and chlorine levels for the purposes of this
alternative standard provision.
---------------------------------------------------------------------------

\255\ As explained earlier, the emission standards for metals
and chlorine reflect the performance of MACT control, which includes
control of metals and chlorine in the hazardous waste feed
materials. As further explained, sources are not required to adopt
MACT control. Sources must, however, achieve the level of
performance which MACT control achieves. Therefore, sources are not
required to control metals and chlorine hazardous waste feedrates to
the same levels as MACT control in order to comply with the
standards for metals and chlorine. Rather, the source can elect to
achieve the emission standard by any means, which may or may not
involve hazardous waste feedrate control
---------------------------------------------------------------------------

b. What Comments Did We Receive on Our Approaches? There were many
comments supporting and many opposing the concept of allowing
alternative standards. Several commenters focus on the Agency's legal
basis for this type of alternative standard. Some, supporting an
alternative standard, wrote that feedrate control of raw materials at
mineral processing plants is not a permissible basis for MACT control.
In support of their position, some directed our attention to the
language found in the Conference Report to the 1990 CAA
amendments.²⁵⁶ However, as we noted in the April 1996 NPRM
and as was mentioned by many commenters ²⁵⁷, the Conference
Report language is not reflected in the statute. Section 112(d)(2)(A)
of the statute states, without caveat, that MACT standards may be based
on ``process changes, substitution of materials or other
modifications.''
---------------------------------------------------------------------------

\256\ H.R. Rep. No. 101-952, at p. 339, 101st Cong., 2d Sess.
(Oct. 26, 1990).
\257\ See 62 FR 24239, May 2, 1997.
---------------------------------------------------------------------------

As noted above, our MACT approach in today's rule relies on metal
and chlorine hazardous waste feedrate controlas part of
developing MACT emission standards. It should be noted, that we do not
directly regulate raw material metal and chlorine input under this
approach, although there is no legal bar for us to do so. Since raw
material feedrate control is not an industry practice, raw material
feedrate control is not part of the MACT floor. In addition, we do not
adopt such control as a beyond-the-floor standard. We conclude it is
not cost-effective to require kilns to control metal and chlorine
emissions by substituting their current raw materials with off-site raw
materials. (See metal and chlorine emission standard discussions for
cement kilns and lightweight aggregate kilns in Part Four, Sections VII
and VIII.) ²⁵⁸
---------------------------------------------------------------------------

\258\ The nonhazardous waste Portland Cement Kiln MACT
rulemaking likewise controls semivolatile metal and low volatile
metal emissions by limiting particulate matter emissions, and did
not adopt beyond-the-floor standards based on raw material metal and
chlorine feedrate control--see 64 FR 31898.
---------------------------------------------------------------------------

Although today's rule offers a petition process, we considered
varying levels of metal and chlorine emissions attributable to raw
material in identifying the metal and chlorine emission standards
through our MACT floor methodology. This consideration helps to ensure
that the emission standards are achievable for sources using MACT
control. Therefore, we anticipate very few sources, if any, will need
to petition the Administrator for alternative standards. However, it is
possible that raw material hazardous air pollutant levels, at a given
kiln location, could vary over time and preclude kilns from achieving
the emission standards. We believe, therefore, that it is appropriate
to adopt a provision to allow kilns to petition for alternative
standards so that future changes in raw material feedstock will not
prevent compliance with today's emission standards.
Other commenters believe that alternative standards are not
necessary because there are kilns with relatively high raw material
metal concentrations already achieving the proposed standards. To
address this point, and to reevaluate the ability of kilns to achieve
the emission standards without new control of metals and chlorine in
raw material and conventional fuel, we again estimated the total metal
and chlorine emissions, assuming each kiln fed metal and chlorine at
the defined MACT feedrate control levels.²⁵⁹
---------------------------------------------------------------------------

\259\ When estimating emissions, the Agency assumed the kiln was
feeding metals and chlorine in its hazardous waste at the lower of
the MACT defining maximum theoretical emission concentration levels
or the level actually demonstrated during its performance test. See
Final Technical Support Document for Hazardous Waste Combustor MACT
Standards, Volume II: Selection of MACT Standards and Technologies,
July 1999, for further discussion.
---------------------------------------------------------------------------

The following table summarizes the estimated achievability of the
emission standards assuming kilns used MACT control. Our analysis
determined achievability both at the emission standard and at the
design level--70 percent of the standard. (To ensure compliance most
kilns will ``design'' their system to operate, at a minimum, 30 percent
below the standard.) The table describes the number of test conditions
in our data base that would not meet the emission standard or meet the
design level by estimating total emissions. For example, all cement
kiln test conditions achieve the mercury emission standard, assuming
all cement

[[Page 52964]]

kilns used MACT control. On the other hand, the table also indicates
that four cement kiln test conditions out of 27 do not achieve the
design level for mercury. In our analysis, if all test conditions
achieved both the standard and the design level, we concluded that
there is no reason to believe raw material contributions to metal and
chlorine emissions might cause a compliance problem.

Cement Kiln and Lightweight Aggregate Kiln Emission Standard
Achievability Results
------------------------------------------------------------------------
Low
Source category Mercury Semivolatile Volatile Total
metal metal chlorine
------------------------------------------------------------------------
No. of cement kiln test \1\0/27 \1\1/38 \1\1/39 \1\2/42
conditions in MACT data base
not achieving standard......
No of cement kiln test 4/27 6/38 3/39 3/42
conditions in MACT data base
not achieving 70 % design
level.......................
No of lightweight aggregate 0/17 5/22 2/22 3/18
kiln test conditions in MACT
data base not achieving
standard....................
No of lightweight aggregate 0/17 5/22 4/22 10/18
kiln test conditions in MACT
data base not achieving 70%
design level................
------------------------------------------------------------------------
*Number after slash denotes total number of test conditions.

Our analysis illustrates that, subject to the assumptions made,
some lightweight aggregate kilns and cement kilns have raw material
hazardous air pollutant levels that could affect their ability to
achieve the emission standard if no additional emission controls were
implemented (e.g., additional hazardous waste feedrate control, or
better air pollution control device efficiency). Nevertheless, we
conclude that it is difficult to determine whether raw material
hazardous air pollutant contributions to the emissions result in
unachievable emission standards because of the difficulty associated
with differentiating raw material hazardous air pollutant emissions
from hazardous waste pollutant emissions. This uncertainty has led us
to further conclude that it is appropriate to allow kilns to petition
for alternative standards, provided that they submit site-specific
information that shows raw material hazardous air pollutant
contributions to the emissions prevent the kiln from complying with the
emission standard even though the kiln is using MACT control.
Many commenters dislike the idea of an alternative standard. They
wrote that regulation of raw material metal content may be necessary to
control semivolatile metal and low volatile metal emissions at
hazardous waste burning kilns because: (1) These kilns have relatively
high chlorine levels in the flue gas (which predominately originate
from the hazardous waste); and (2) chlorine tends to increase metal
volatility. We agree that increased flue gas chlorine content from
hazardous waste burning operations may result in increased metals
volatility, which then could result in higher raw material metal
emissions.²⁶⁰ The increased presence of chlorine at
hazardous waste burning kilns presents a concern. To address this
concern, we require kilns to submit data or information, as part of the
alternative standard petition, documenting that increased chlorine
levels associated with the burning of hazardous waste, as compared to
nonhazardous waste operations, do not significantly increase metal
emissions attributable to raw material. This requirement is explained
in greater detail later in this section.
---------------------------------------------------------------------------

\260\ The potential for increased metal emissions is stronger
for semivolatile metals (lead, in particular), but low volatile
metal emissions still have potential to increase with increased flue
gas chlorine concentrations. See Final Technical Support Document
for Hazardous Waste Combustor MACT Standards, Volume II: Selection
of MACT Standards and Technologies, July 1999, for further
discussion.
---------------------------------------------------------------------------

Many commenters also point out that the alternative standard, at
least as originally proposed, could result in metal and chlorine
emissions exceeding the standard to possible levels of risk to human
health and the environment. We agree that this potential could exist;
however, the RCRA omnibus process serves as a safeguard against levels
of emissions that present risk to human health or the environment.
Therefore, sources operating pursuant to alternative standards may
likely be required to perform a site-specific risk assessment to
demonstrate that their emissions do not pose an unacceptable risk. The
results of the risk assessment would then be used to develop facility-
specific metal and chlorine emission limits (if necessary), which would
be implemented and enforced through omnibus conditions in the RCRA
permit.²⁶¹
---------------------------------------------------------------------------

\261\ RCRA permits for hazardous waste combustors address total
emissions, regardless of the source of the pollutant due to the
nexus with the hazardous waste treatment activities. See Horsehead v
Browner, 16 F. 3d 1246, 1261-63 (D.C. Cir. 1994)(Hazardous waste
combustion standards may address hazardous constituents attributable
to raw material inputs so long as thee is a reasonable nexus with
the hazardous waste combustion activites).
---------------------------------------------------------------------------

c. How Do I Demonstrate Eligibility for the Alternative Standard?
To demonstrate eligibility, you must submit data or information which
shows that raw material hazardous air pollutant contributions to the
emissions prevent you from complying with the emission standard, even
though you use MACT control for the standard from which you seek
relief. To allow flexibility in implementation, we do not mandate what
this demonstration must entail. However, we believe that a
demonstration should include a performance test while using MACT
control or better (i.e., the hazardous waste feedrate control and air
pollution control device efficiencies that are the basis of the
emission standard from which you seek an alternative). If you still do
not achieve the emission standards when operating under these
conditions, you may be eligible for the alternative standard (provided
you further demonstrate that you meet the additional eligibility
requirements discussed below). If you choose to conduct this
performance test after your compliance date, you should first obtain
approval to temporarily exceed the emission standards (for testing
purposes only) to make this demonstration, otherwise you may be subject
to enforcement action.
In addition, you must make a showing of adequate system removal
efficiency to be eligible for an alternative standard for semivolatile
metal, low volatile metal, or hydrochloric acid/chlorine gas. This
requirement provides a check to ensure that you are exceeding the
emission standard solely because of raw material contributions to the
emissions, and not because of poor system removal efficiency for the
hazardous air pollutants for which you are seeking relief. (It is
possible that poor system removal efficiencies for these hazardous air
pollutants result in emissions that are higher than the emission
standards, even though the particulate matter emission standard is
met.) This check could be done without the expense of a second
performance test. The system removal efficiency achieved in the
performance test described above could be calculated for the hazardous
air pollutants at issue. You would then

[[Page 52965]]

multiply the MACT control hazardous waste feedrate level (or the
feedrate level you choose to comply with) ²⁶² for the same
hazardous air pollutant by a factor of one minus the system removal
efficiency. This estimated emission value would then be compared to the
emission standard, and would have to be below the standard for you to
qualify for the alternative standard.
---------------------------------------------------------------------------

You may choose to comply with a hazardous waste feedrate limit
that is lower than the MACT control levels required by this
alternative standard.
---------------------------------------------------------------------------

As discussed in the next section, this alternative standard
requires you to use MACT control as defined in this rulemaking. For
lightweight aggregate kilns, MACT control for chlorine is feedrate
control and use of an air pollution control system that achieves a
given system removal efficiency for chlorine. Thus, lightweight
aggregate kilns that petition the Administrator for an alternative
chlorine standard must also demonstrate, as part of a performance test,
that it achieves a specified minimum system removal efficiency for
chlorine. This eligibility requirement is identical to the above-
mentioned eligibility demonstration that requires sources to make a
showing of adequate system removal efficiency, with the exception that
here we specify the system removal efficiency that must be
achieved.²⁶³
---------------------------------------------------------------------------

\263\ The requirement to achieve an 85.0% and 99.6% chlorine
system removal efficiency for existing and new lightweight aggregate
kilns, respectively, together with the requirement to comply with a
hazardous waste chlorine feedrate limitation, ensures that chlorine
emissions attributable to hazardous waste are below the standards.
---------------------------------------------------------------------------

For an alternative mercury standard, you do not have to perform a
performance test demonstration and evaluation. We do not require this
test because the mandatory hazardous waste mercury feedrate specified
in Sec. 63.1206(b)(10) and (11) ensures that your hazardous waste
mercury contribution to the emissions will always be below the mercury
standard.²⁶⁴
---------------------------------------------------------------------------

\264\ The MACT defining hazardous waste maximum theoretical
emission concentration for mercury is less than mercury standard
itself, thus hazardous waste mercury contributions to the emissions
will always be below the standard.
---------------------------------------------------------------------------

Finally, if you apply for semivolatile metal or low volatile metal
alternative standards, you also must demonstrate, by submitting data or
information, that increased chlorine levels associated with the burning
of hazardous waste, as compared to nonhazardous waste operations, do
not significantly increase metal emissions attributable to raw
material. We expect that you will have to conduct two different
emission tests to make this demonstration (although the number of tests
should be determined on a site-specific basis). The first test is to
determine metal emission concentrations when the kiln is burning
conventional fuel with typical chlorine levels. The second test is to
determine metal emissions when chlorine feedrates are equivalent to
allowable chlorine feedrates when burning hazardous waste. You should
structure these tests so that metal feedrates for both tests are
equivalent. You would then compare metal emission data to determine if
increased chlorine levels significantly affects raw material metal
emissions.
d. What Is the Format of the Alternative Standard? The alternative
standard requires that you use MACT control, or better, as applicable
to the standard for which you seek the alternative. MACT control, as
previously discussed, consists of hazardous waste feed control plus
(for all relevant hazardous air pollutants except mercury) further
control via air pollution control devices. Cement kilns and lightweight
aggregate kilns will first have to comply with a specified hazardous
waste metal and chlorine feedrate limit, as defined by the MACT
defining maximum theoretical emission concentration level for the
applicable hazardous air pollutant or hazardous air pollutant group.
This work practice is necessary because there is no other reliable
means of measuring that hazardous air pollutants in hazardous waste are
controlled to the MACT control levels, i.e., that hazardous air
pollutants in raw material are the sole cause of not achieving the
emission standard. (See CAA section 112(h).) To demonstrate control of
hazardous air pollutant metals emissions to levels reflecting the air
pollution control device component of MACT control, you must be in
compliance with the particulate matter standard. Finally, we require
lightweight aggregate kilns to use an air pollution control device that
achieves the specified MACT control total chlorine removal efficiency.
This work practice is necessary because there is no other way to
measure whether the failure to achieve the chlorine emission standard
is caused by chlorine levels in raw materials.²⁶⁵ See
Sec. 63.1206(b)(10) and (11) for a list of the maximum achievable
control technology requirements for purposes of this alternative
standard.²⁶⁶
---------------------------------------------------------------------------

\265\ There is no corresponding chlorine air pollution control
device efficiency requirement for cement kilns since air pollution
control is not the basis for MACT control of cement kiln chlorine
emissions.
\266\ See also ``Final Technical Support Document for Hazardous
Waste Combustor MACT Standards, Volume IV: Selection of MACT
Standards and Technologies'', Chapter 11, July 1999, for further
discussion on how the maximum achievable control technologies were
chosen for the hazardous air pollutants.
---------------------------------------------------------------------------

There may be site-specific circumstances which require other
provisions, imposed by the Administrator, in addition to the mandatory
requirement to use MACT control. These provisions could be operating
parameter requirements such as a further hazardous waste feedrate
limitation. For instance, a kiln that petitions the Administrator for
an alternative semivolatile emission standard may need to limit its
hazardous waste chlorine feedrate to better assure that chlorine
originating from the hazardous waste does not significantly affect
semivolatile metal emissions attributable to the raw material. As
discussed above, a kiln must demonstrate that increased chlorine levels
from hazardous waste do not adversely affect raw material metal
emissions to be eligible for this alternative standard. For this
scenario, the alternative standard would be in the form of a
semivolatile metal hazardous waste feedrate restriction which would
require you to use MACT control, in addition to a hazardous waste
chlorine feedrate limit.
Additional provisions also could include emission limitations that
differ from those included in today's rulemaking. For example, the
Administrator may determine it appropriate to require you to comply
with metal or chlorine emission limitations that are than the standards
in this final rulemaking. The emission limitation would likely consider
the elevated levels of metal or chlorine in your raw material. This
type of emission limitation would be no different, except for the
numerical difference than the emission limitations in today's rule
because it would limit total metal and chlorine emissions while at the
same time ensuring MACT control is used. If the Administrator
determines that such an emission limitation is appropriate, you must
comply with both a hazardous waste feedrate restriction, which requires
you to use MACT control, and an emission limitation. A potential method
of determining an appropriate emission limitation would be to base the
limit on levels demonstrated in the comprehensive performance test.
e. What Is the Process for an Alternative Standard Petition? If you
are seeking alternative standards because raw materials cause you to
exceed the standards, you must submit a petition request to the
Administrator that includes your recommended alternative

[[Page 52966]]

standard provisions. At a minimum, your petition must include data or
information which demonstrates that you meet the eligibility
requirements and that ensure you use MACT control, as defined in
today's rule.
Until the authorized regulatory agency approves the provisions of
the alternative standard in your petition (or establishes other
alternative standards) and until you submit a revised NOC that
incorporates the revised standards, you may not operate under your
alternative standards in lieu of the applicable emission standards
found in Secs. 63.1204 and 63.1205. We recommend that you submit a
petition well in advance of your scheduled comprehensive performance
test, perhaps including the petition together with your comprehensive
performance test plan. You may need to submit this petition in phases
to ultimately receive approval to operate pursuant to the alternative
standard provisions, similar to the review process associated with
performance test workplans and performance test reports. After initial
approval, alternative standard petitions should be resubmitted every
five years for review and approval, concurrent with subsequent future
comprehensive performance tests, and should contain all pertinent
information discussed above.
You may find it necessary to complete any testing associated with
documenting your eligibility requirements prior to your comprehensive
performance test to determine if in fact you are eligible for this
alternative standard, or you may choose to conduct this testing at the
same time you conduct your comprehensive performance test. This should
be determined on a site-specific basis, and will require coordination
with the Administrator or Administrator's designee.
2. What Special Provisions Exist for an Alternative Mercury Standard
for Kilns?
See Sec. 63.1206(b)(10) and (11).
a. What Happens if Mercury Is Historically Not Present at
Detectible Levels? Situations may exist in which a kiln cannot comply
with the mercury standard pursuant to the provisions in Sec. 63.1207(m)
when using MACT control and when mercury is not present in the raw
material at detectable levels.²⁶⁷ As a result, today's rule
provides a petition process for an alternative mercury standard which
only requires compliance with a hazardous waste mercury feedrate
limitation, provided that historically mercury not been present in the
raw material at detectable levels.
---------------------------------------------------------------------------

\267\ The provisions in Sec. 63.1207(m) waive the requirement
for you to conduct a performance test, and the requirement to set
operating limits based on performance test data, provided you
demonstrate that uncontrolled mercury emissions are below the
emission standard (see Part 4, Section X.B). These provisions allow
you to assume mercury is present at half the detection limit in the
raw material, when a feedstream analysis determines that mercury is
not present at detectable levels, when calculating your uncontrolled
emissions.
---------------------------------------------------------------------------

We received comments from the lightweight aggregate kiln industry
expressing concern with the stringency of the mercury standard.
Commenters oppose stringent mercury standards, in part, because of the
difficulty of complying with day-to-day mercury feedrate limits. One
potential problem cited pertains to raw material mercury detection
limits. Commenters point out that if a kiln assumed mercury is present
in the raw material at the detection limit, the resulting calculated
uncontrolled mercury emission concentration could exceed, or be a
significant percentage of, the mercury emission standard. This may
prevent a kiln from complying with the mercury emission standard
pursuant to the provisions of Sec. 63.1207(m), even though MACT control
was used.
We agree with commenters that this is a potential problem. In
addition, it is not appropriate to implement a mercury standard
compliance scheme that is relatively more burdensome for kilns with no
mercury present in raw material, as compared to kilns with high levels
of mercury in their raw material.²⁶⁸ Because we establish
provisions that provide alternatives to kilns with high levels of
mercury in the raw material, we are doing the same for those kilns
which do not have mercury present in raw material at detectable levels.
---------------------------------------------------------------------------

\268\ Kilns that comply with alternative mercury standards
because of high mercury levels in their raw material are not
required to monitor the mercury content of their raw material unless
the Administrator requires this as an additional alternative
standard requirement. Thus, absent the alternative mercury standard
discussed in this section, a source that does not have mercury
present in their mercury at detectable levels would be subject to
more burdensome raw material feedstream analysis requirements.
---------------------------------------------------------------------------

b. What Are the Alternative Standard Eligibility Requirements? To
be eligible for this alternative mercury standard, you must submit data
or information which demonstrates that historically mercury has not
been present in your raw material at detectable levels. You do not need
to show that mercury has never been present at detectable levels. The
determination of whether your data and information sufficiently
demonstrate that mercury has not historically been present in your raw
material at detectable levels will be made on a site-specific basis. To
assist in this determination, you also should provide information that
describes the analytical methods (and their associated detection
limits) used to measure mercury in the raw material, together with
information describing how frequently you measured raw material mercury
content.
If you are granted this alternative standard, you will not be
required to monitor mercury content in your raw material for compliance
purposes. However, after initial approval, this alternative standard
must be reapproved every five years (see discussion below). Therefore,
you should develop a raw material mercury sampling and analysis program
that can be used in future alternative mercury standard petition
requests for the purpose of demonstrating that mercury has not
historically been present in raw material at detectable levels.
c. What Is the Format of Alternative Mercury Standard? The
alternative standard requires you to use MACT control for mercury
(i.e., the level of hazardous waste feedrate control specified in
today's rule). This alternative standard for mercury is conceptually
identical to the emission standards in this final rule, because it
requires the use of an equivalent level of hazardous air pollutant MACT
control as compared to the MACT control used to determine the emission
standards.
The mercury feedrate control level will differ for new and existing
sources, and will differ for cement kilns and lightweight aggregate
kilns. See Sec. 63.1206(b) (10) and (11) for a list of the mercury
hazardous waste feedrate control levels for purposes of this
alternative standard.²⁶⁹
---------------------------------------------------------------------------

\269\ Also see Final Technical Support Document for Hazardous
Waste Combustor MACT Standards, Volume IV: Selection of MACT
Standards and Technologies, Chapeter 11, July 1999, for further
discussion on how the maximum achievable control technologies were
chosen for mercury.
---------------------------------------------------------------------------

d. What Is the Process for The Alternative Mercury Standard
Petition? If you are seeking this alternative mercury standard, you
must submit a petition request to the Administrator that includes the
required information discussed above. You will not be allowed to
operate under this alternative standard, in lieu of the applicable
emission standards found in Secs. 63.1204 and 63.1205, unless and until
the Administrator approves the provisions of this alternative standard
and until you submit a revised NOC that incorporates this alternative
standard.

[[Page 52967]]

We recommend that you submit these petitions well in advance of your
scheduled comprehensive performance test, perhaps including the
petition together with your comprehensive performance test plan. After
initial approval, alternative standard petitions should be resubmitted
every five years for review and approval, concurrent with subsequent
future comprehensive performance tests, and should contain all
pertinent information discussed above.
B. Under What Conditions Can the Performance Testing Requirements Be
Waived? See Sec. 63.1207(m).
In the April 1996 NPRM, we proposed a waiver of performance testing
requirements for sources that feed low levels of mercury, semivolatile
metal, low volatile metal, or chlorine (see 61 FR at 17447). Under the
proposed waiver, a source would be required to assume that all mercury,
semivolatile metal, low volatile metal, or chlorine (dependent on which
hazardous air pollutant(s) the source wishes to petition for a waiver)
fed to the combustion unit, for all feedstreams, is emitted from the
stack. The source also would need to show that these uncontrolled
emission concentrations do not exceed the associated emission
standards, taking into consideration stack gas flow rate. The above
requirements would apply for all periods that a source elects to
operate under this waiver and for which the source is subject to the
requirements of this rulemaking. All comments received on this topic
support this approach, and no commenters suggest alternative procedures
to implement this provision. Today's rule finalizes the proposed
performance test waiver provision, with one minor change expected to
provide industry with greater flexibility when demonstrating compliance
without compromising protectiveness.
1. How Is This Waiver Implemented?
The April 1996 proposal identified two implementation methods to
document compliance with this waiver provision. In today's rule we
finalize both proposed methods and add another implementation method to
provide greater flexibility when demonstrating compliance with the
provisions of this performance test waiver. As proposed, the first
approach allows establishment and continuous compliance with one
maximum total feedstream feedrate limit for mercury, semivolatile
metal, low volatile metal, or chlorine and one minimum stack gas flow
rate. The combined maximum feedrate and minimum stack gas flow rate
must result in uncontrolled emissions below the applicable mercury,
semivolatile metal, low volatile metal, or chlorine emission standards.
Both limits would be complied with continuously; any exceedance would
require the initiation of an automatic waste feed cut-off.
Also as proposed, the second approach accommodates operation under
different ranges of stack gas flow rates and/or metal and chlorine
feedrates. Today's rule allows establishment of different modes of
operation with corresponding minimum stack gas flow rate limits and
maximum feedrates for metals or chlorine. If you use this approach, you
must clearly identify in the operating record which operating mode is
in effect at all times, and you must properly adjust your automatic
waste feed cutoff levels accordingly.
The third approach, which is an outgrowth of our proposed
approaches, allows continuous calculation of uncontrolled stack gas
emissions, assuming all metals or chlorine fed to combustion unit are
emitted out the stack. If you use this approach, you must record these
calculated values and comply with the mercury, semivolatile metal, low
volatile metal, or chlorine emission standards on a continuous basis.
This approach provides greater operational flexibility, but increases
recordkeeping since the uncontrolled emission level must be
continuously recorded and included in the operating record for
compliance purposes.
If you claim this waiver provision, you must, in your performance
test workplan, document your intent to use this provision and explain
which implementation approach is used. Other than those limits required
by this provision, you will not be required to establish or comply with
operating parameter limits associated with the metals or chlorine for
which the waiver is claimed. Your NOC also must specify which
implementation method is used. The NOC must incorporate the minimum
stack gas flowrate and maximum metal and chlorine feedrate as operating
parameter limits, or include a statement which specifies that you will
comply with emission standard(s) by continuously recording your
uncontrolled metal and chlorine emission rate.
If you cannot continuously monitor stack gas flow rate, for the
purpose of demonstrating compliance with the provisions of this waiver,
you may use an appropriate surrogate in place of stack gas flow rate
(e.g., cement kiln production rate). However, if you use a surrogate,
you must provide in your performance test workplan data that clearly
and reasonably correlates the surrogate parameter to stack gas flow
rate.
2. How Are Detection Limits Handled Under This Provision?
We did not address in April 1996 NPRM how nondetect metal and
chlorine feedstream results are handled when demonstrating compliance
with the feedrate limits or when calculating uncontrolled emission
concentrations under this provision. Commenters likewise did not offer
suggestions of how to handle nondetect data for this provision. After
careful consideration, for the purposes of this waiver, we require that
you must assume that the metals and chlorine are present at the full
detection limit value when the analysis determines the metals and
chlorine are not detected in the feedstream (except as described in the
following paragraph). Because performance testing is waived under this
provision, it is appropriate to adopt a more conservative assumption
that metals and chlorine are present at the full detection limit for
the purposes of this waiver. (In other portions of today's rule we make
the assumption that 50 percent presence is appropriate given the
different context involved). Assuming full detection limits provides an
additional level of assurance that resulting emissions still reflect
MACT and do not pose a threat to human health and the environment. If
you cannot demonstrate compliance with the provisions of this waiver
when assuming full detection limits, then you should not claim this
waiver and should conduct emissions testing to demonstrate compliance
with the emission standard.
Based on the comments and as discussed in the previous section
(Section A.2.a), we conclude it is not appropriate, for purposes of
this performance test waiver provision, to require a kiln to assume
mercury is present at the full detection limit in its raw material when
the feedstream analysis determines mercury is not present at detectable
levels. As a result, we allow kilns to assume mercury is present at
one-half the detection limit in raw materials when demonstrating
compliance with the performance test waiver provisions whenever the raw
material feedstream analysis determines that mercury is not present at
detectable levels.
C. What Other Waiver Was Proposed, But Not Adopted?
Waiver of the Mercury, Semivolatile Metal, Low Volatile Metal, or
Chlorine Standard

[[Page 52968]]

We proposed not to subject sources to one or more of the mercury,
semivolatile metal, low volatile metal, or chlorine emission standards
(and other requirements) ²⁷⁰ if their feedstreams did not
contain detectable levels of that associated metal or chlorine (e.g.,
if their feedstreams did not contain a detectable level of chlorine,
the hydrochloric acid/chlorine gas standard would be waived--see 61 FR
at 17447). As part of this waiver, a feedstream sampling and analysis
plan would be developed and implemented to document that feedstreams
did not contain detectable levels of the metals or chlorine.
---------------------------------------------------------------------------

\270\ Ancillary performance testing, monitoring, notification,
record keeping, and reporting requirements.
---------------------------------------------------------------------------

Several commenters supported this waiver, stating that it is of no
benefit to human health or the environment to require performance
testing, monitoring, notification, and record-keeping of constituents
not fed to the combustion unit. However, commenters were divided in
their support of the need to set minimum feedstream detection limits.
Those supporting specified detection limits wrote that detection limits
are needed to ensure that appropriate analytical procedures are used
and needed to provide consistency between sources. Those opposing
specified detection limits believed that detection limits are highly
dependent on feedstream matrices. Therefore, to impose a detection
limit that applies to all sources and all feedstreams would not be
practicable. One commenter questioned basing this waiver on nondetect
values because a feedstream analyses that detects, at any time, a
quantity of the metal or chlorine just above the detection limit may be
considered to be out of compliance.
We agree that little or no environmental benefit may be gained by
requiring performance testing, monitoring, notification, and record
keeping for a constituent not fed to the combustion unit. However,
based on our careful analysis of comments and on our reevaluation of
the practical implementation issue inherent in this type of waiver, we
find that it may not always be practicable to use detection limits to
determine if a waste does or does not contain metals or chlorine. We
are concerned that facility-specific detection limits may vary, from
source to source, at levels such that sources with detection limits in
the high-end of the distribution (due to their complex waste matrix)
have the potential for significant metal or chlorine emissions. Under
the facility-specific detection limit approach, a high-end detection
limit source with relatively high emissions could qualify for the
waiver; however, a source with a simpler feedstream matrix with
significantly lower amounts of metals in the feedstream (but just above
the detection limit) would not qualify. This not only turns the
potential benefit of a waiver provision on its head, but raises serious
questions of national consistency, fairness, and evenness of
environmental protection to surrounding communities. We also conclude
that it is impractical to set one common detection limit for each
hazardous air pollutant as part of this waiver because, as commenters
stated, detection limits are matrix dependent.
Due to these issues, we were unable to devise an implementable and
acceptable nondetect waiver provision, and therefore do not adopt one
in today's final rule. As is described in the previous section (Section
B), however, we do provide a waiver of performance testing requirements
to sources that feed low levels of mercury, semivolatile metal, low
volatile metal, or chlorine. Although this waiver provision does not
waive the emission standard, monitoring, notification, recordkeeping,
and reporting requirements, it does waive emission tests and compliance
with operating parameter limits for the associated metals or chlorine.
D. What Equivalency Determinations Were Considered, But Not Adopted?
In response to comments we received from the April 1996 NPRM, we
included in the May 1997 NODA a discussion of an allowance of a one-
time compliance demonstration for hydrocarbon and carbon monoxide at
cement kilns equipped with temporary midkiln sampling locations. (See
62 FR 24239.) This equivalency determination required that alternative,
continuously monitored, operating parameters be used in lieu of
continuous monitoring of hydrocarbon/carbon monoxide. As discussed
below, we conclude that the shortcomings associated with the proposed
alternative operating parameters created sufficient uncertainties, for
implementation and overall environmental protection, that we are not
adopting an equivalency determination option in this rulemaking.
However, cement kilns have the opportunity to petition the
Administrator under Sec. 63.8(f) and 63.1209(g)(1) to make a site-
specific case for this type of equivalency determination.
In response to the April 1996 NPRM, we received comments indicating
that some kilns would need to either operate at inefficient back-end
temperatures (to oxidize hydrocarbons desorbed from the raw material)
or be required to install and maintain a midkiln sampling system to
demonstrate compliance with the hydrocarbon/carbon monoxide standards.
Commenters believe that this may not be feasible for some kilns
because: (1) Raising back end temperatures may increase dioxin
formation; (2) most long kilns are not equipped to sample emissions at
the midkiln location; (3) costs associated with retrofit and
maintenance may be considered high; and (4) maintenance problems
associated with the sampling duct are difficult to overcome.
We received numerous comments on the proposed hydrocarbon/carbon
monoxide equivalency approach described in the May 1997 NODA. Many
cement kilns support the option and defend the use of alternative
operating parameters in lieu of continuous carbon monoxide and
hydrocarbon monitors. Many commenters oppose using any parameters other
than carbon monoxide or hydrocarbon as a combustion efficiency
indicator and as surrogate emission standards for the nondioxin organic
hazardous air pollutants. We have found that a number of factors
suggest that a special provision allowing use of alternative operating
parameters, in lieu of carbon monoxide and/or hydrocarbon, is neither
necessary nor appropriate to include in this rulemaking.
The alternative operating parameters associated with a one-time
demonstration would have to assure that compliance with the carbon
monoxide/hydrocarbon standard is maintained at the midkiln location on
a continuous basis. We considered adopting several different operating
parameters in lieu of hydrocarbon/carbon monoxide monitoring to achieve
this goal. Maximum production rate was considered as a continuous
residence time indicator. Minimum combustion zone temperature,
continuously monitored destruction and removal efficiency using sulphur
hexafluoride, and minimum effluent NOX limits were also
examined to ensure adequate temperature is continuously maintained in
the combustion zone. To ensure adequate turbulence, we considered using
minimum kiln effluent oxygen concentration. Commenters did not suggest
additional alternative operating parameters.
Each of these operating parameters have potential shortcomings, and
we are not convinced that use of these parameters, even in combination,
provides a combustion efficiency indicator as reliable as continuous

[[Page 52969]]

hydrocarbon/carbon monoxide monitoring. We have identified the
following potential problems with these alternative operating
parameters: (1) Effluent kiln oxygen concentration may not correlate
well to carbon monoxide/hydrocarbon produced from oxygen deficient
zones in the kiln; ^271,272 (2) pyrometers, or other
temperature monitoring systems, may not provide direct and reliable
measurements of combustion zone temperature; ²⁷³ (3) some
combustion products of sulphur hexaflouride are toxic and regulated
hazardous air pollutants; ²⁷⁴ (4) there are no demonstrated
performance specifications for continuous sulphur hexaflouride
monitors; and (5) it is contrary to other air emission limitations (in
principle) to require minimum (not maximum) NOX limits.
---------------------------------------------------------------------------

\271\ An oxygen deficient zone in the kiln due to inadequate
mixing, which could potentially result in the emission of
significant amounts of carbon monoxide and organic hazardous air
pollutants, could be well mixed with excess air by the time it
reaches the kiln exit, where oxygen is monitored. Thus the oxygen
monitor may not record any oxygen concentration change and would not
serve as an adequate control to ensure proper combustion turbulence.
\272\ We do not have, nor did commenters submit, data which show
whether effluent kiln oxygen concentration adequately correlates
with carbon monoxide/hydrocarbon produced from oxygen deficient
zones in the kiln.
\273\ See Part Five, Section VII.D.(2)(b)(iii), for further
discussion on combustion zone temperature measurements.
\274\ Hydrofluoric acid, a CAA hazardous air pollutant, is a
possible combustion byproduct of sulphur hexafluoride.
---------------------------------------------------------------------------

On balance, the lack of adequate documentation allowing us to
resolve these uncertainties and potential problem areas prevents us
from further considering this type of hydrocarbon/carbon monoxide
equivalency determination provision for inclusion in today's final
rule. As stated above, however, cement kilns have the opportunity to
petition the Administrator under Sec. 63.8(f) to make a site-specific
case for this type of equivalency determination.
As is explained in Part Four, Section VII.C(9)(c), today's
rulemaking subjects newly constructed hazardous waste burning cement
kilns at greenfield sites to a main stack hydrocarbon standard of
either 20 or 50 ppmv. We clarify that this standard applies to these
sources even if they applied and received approval for an alternative
monitoring approach described above, because the intent of this
hydrocarbon standard is to control organic hazardous air pollutants
desorbed from raw material and not to control combustion efficiency.
E. What are the Special Compliance Provisions and Performance Testing
Requirements for Cement Kilns with In-line Raw Mills and Dual Stacks?
Preheater/precalciner cement kilns with dual stacks and cement
kilns with in-line raw mills require special compliance provisions and
performance testing requirements because they are unique in design.
Preheater/precalciner kilns with dual stacks have two separate air
pollution control systems. As discussed in Section F below, emission
characteristics from these separate stacks could be different. As a
result, these kilns must conduct emission testing in both stacks to
document compliance with the emission standards ²⁷⁵ and must
establish separate operating parameter limits for each air pollution
control device. See Sec. 63.1204(e)(1).
---------------------------------------------------------------------------

\275\ This does not apply to the hydrocarbon and carbon monoxide
standard. See discussion in Part Four, Section VII.D on hydrocarbon
and carbon monoxide standards for cement kilns.
---------------------------------------------------------------------------

Cement kilns with in-line raw mills either operate with the raw
mill on-line or with the raw mill off-line. As discussed in Section F
below, these two different modes of operation could have different
emission characteristics. As a result, cement kilns with in-line raw
mills must conduct emission testing when the raw mill is off-line and
when the raw mill is on-line to document compliance with the emission
standards and must establish separate operating parameters for each
mode of operation. These kilns must document in the operating record
each time they change from one mode of operation to the alternate mode.
They must also begin calculating new rolling averages for operating
parameter limits and comply with the operating parameter limits for
that mode of operation, after they officially switch modes of
operation. If there is a transition period associated with changing
modes of operation, the kiln operator has the discretion to determine
when, during this transition, the kiln has officially switched to the
alternate mode of operation and when it must begin complying with the
operating parameter limits for that alternate mode of operation. See
63.1204(d)(1).
Preheater/precalciner kilns with dual stacks that also have in-line
raw mills do not have to conduct dioxin/furan testing in the bypass
stack to demonstrate compliance with the standard when the raw mill is
off-line. We have concluded that dioxin/furan emissions in the bypass
stack are not dependent on the raw mill operating status because
dioxin/furan emissions are primarily dependent on temperature control.
A kiln may assume that when the raw mill is off-line, the dioxin/furan
emissions in the bypass stack are identical to the dioxin/furan
emissions when the raw mill is on-line and may comply with the bypass
stack dioxin/furan raw mill on-line operating parameters for both modes
of operation. See Sec. 63.1204(d)(1).
F. Is Emission Averaging Allowable for Cement Kilns with Dual Stacks
and In-line Raw Mills?
In the April 1996 NPRM, we did not subdivide cement kilns by
process type when setting emission standards (see 61 FR at 17372-
17373). As a result, we received many comments from the cement kiln
industry indicating that preheater/precalciner cement kilns with dual
stacks and cement kilns with in-line raw mills have unique design and
operating procedures that necessitate the use of emission averaging
when demonstrating compliance with the emission standards. We addressed
these comments in the May 1997 NODA by discussing an allowance for
emission averaging (for all standards except for hydrocarbon/carbon
monoxide) at preheater/precalciner cement kilns with dual stacks when
demonstrating compliance with the emission standards (see 62 FR at
24240). We also discussed allowing cement kilns with in-line raw mills
to demonstrate compliance with the emission standards on a time-
weighted average basis to account for different emission
characteristics when the raw mill is active as opposed to when it is
inactive. In light of the favorable comments received, and the lack of
significant concerns to the contrary, we adopt these emission averaging
provisions in today's rule.
1. What Are the Emission Averaging Provisions for Cement Kilns with In-
line Raw Mills?
See Sec. 63.1204(d).
As explained in the May 1997 NODA, emissions of hazardous air
pollutants can be different when the raw mill is active versus periods
of time when the mill is out of service. We received many comments on
this issue, all in favor of an emissions averaging approach to
accommodate these different modes of operation. As a result, we adopt a
provision that allows cement kilns that operate in-line raw mills to
average their emissions on a time-weighted basis to show compliance
with the metal and chlorine emission standards.
Emission averaging for in line raw mills will not be allowed when
they demonstrate compliance with the hydrocarbon/carbon monoxide
standard

[[Page 52970]]

because hydrocarbon and carbon monoxide are monitored continually and
serve as a continuous indicator of combustion efficiency. No commenter
states that emission averaging is needed for hydrocarbon/carbon
monoxide. Emission averaging for particulate matter will not be allowed
because this standard is based on the New Source Performance Standards
found in Sec. 60.60 subpart F. We interpret these standards to apply
regardless if the raw mill is on or off. (Note that this is consistent
with the proposed Nonhazardous Waste Portland Cement Kiln Rule. See 56
FR 14188). In addition, emission averaging for dioxin/furan will not be
allowed because cement kilns with in-line raw mills are expected to
control temperature during both modes of operation to comply with the
standard. No commenter stated that emission averaging was needed for
dioxin/furan.
a. What Is the Averaging Methodology? In the May 1997 NODA, we did
not specify an averaging methodology. As a result, commenters suggested
that the following equation would adequately calculate the time-
weighted average concentration of a regulated constituent when
considering the length of time the in-line raw mill is on-line and off-
line:
[GRAPHIC] [TIFF OMITTED] TR30SE99.028

Where:
Ctotal = time-weighted average concentration of a regulated
constituent considering both raw mill on time and off time.
Cmill-off = average performance test concentration of
regulated constituent with the raw mill off-line.
Cmill-on = average performance test concentration of
regulated constituent with the raw mill on-line.
Tmill-off = time when kiln gases are not routed through the
raw mill.
Tmill-on = time when kiln gases are routed through the raw
mill.

We agree that this equation properly calculates the time-weighted
average concentration of the regulated constituent when considering
both raw mill operation and raw mill down time and are adopting it in
today's rule.
b. What Is Required During Emission Testing? As discussed, sources
that use this emission averaging provision must conduct performance
testing for both modes of operation (with the raw mill both on-line and
off-line), demonstrating appropriate operating parameters during both
test conditions. One commenter suggests that the Agency allow sources
to demonstrate both raw mill on-line and off-line operations within the
same test runs. This would allow a test under one condition instead of
two and would give more flexibility by ensuring identical operating
parameters for raw mill on-line operations as opposed to off-line
operations. This also could theoretically result in fewer automatic
waste feed cutoffs when transitioning from one mode of operation to
another. Although this approach may have some benefit, we conclude that
it is necessary to demonstrate, through separate emission testing, the
comparison of emissions when operating with the raw mill on-line as
opposed to the raw mill off-line. The separate emission testing is
necessary to demonstrate whether emissions are higher or lower when the
raw mill is not active to assure compliance with the emission standards
on a time-weighed basis.²⁷⁶
---------------------------------------------------------------------------

\276\ The Agency does not have, nor did commenters submit,
sufficient data to determine whether emissions will be higher or
lower when the raw mill is inactive.
---------------------------------------------------------------------------

c. How Is Compliance Demonstrated? In the May 1997 NODA, we did not
discuss specific compliance provisions of an emission averaging
approach. After careful consideration, however, we determine that to
use this emission averaging provision, you must document and
demonstrate compliance with the emission standards on an annual basis
by using the above equation. Shorter averaging times were considered,
but were not chosen since it may be difficult for a kiln with an in-
line raw mill to comply with a short averaging period if the raw mill
must be off-line for an extended period of time. Therefore, you must
annually document in your operating record that compliance with the
emission standard was demonstrated for the previous year's operation by
calculating your estimated annual emissions with the above equation.
The one-year block average begins on the day you submit your NOC. You
must include all hazardous waste operations in that one year block
period, and you also must include all nonhazardous waste operations
that you elect to comply with hazardous waste MACT standards, when
demonstrating annual compliance.²⁷⁷
---------------------------------------------------------------------------

\277\ Today's rulemaking allows a hazardous waste source, when
not burning hazardous waste, to either comply with the hazardous
waste cement kiln MACT standards or the non hazardous waste cement
kiln standards (see Part Five, Section I).
---------------------------------------------------------------------------

d. What Notification Is Required? Again, in the May 1997 NODA, we
did not discuss specific notification requirements. After careful
consideration, we determined that if you use this emission averaging
provision, you must notify the Administrator of your intent to do so in
your performance test workplan. Several commenters favor allowing time-
weighted emissions averaging, so long as historical data are submitted
to justify allowable time weighting factors (explained below). We agree
with these comments and require that you submit historical raw mill
operation data in your performance test workplan. These data should be
used to estimate the future down-time the raw mill will experience. You
must document in your performance test workplan that estimated
emissions and estimated raw mill down-time will not result in an
exceedance of the emission standard on an annual basis. You also must
document in your NOC that the emission standard will not be exceeded
based on the documented emissions from the compliance test and
predicted raw mill down-time.
2. What Emission Averaging Is Allowed for Preheater or Preheater-
Precalciner Kilns with Dual Stacks? (See Sec. 63.1204(e).)
As explained in theMay 1997 NODA, and in an earlier
section of this preamble (see Part Four, Section V.II.B), emissions of
hazardous air pollutants can be different in a preheater or preheater-
precalciner cement kiln's main stack as opposed to the bypass stack. We
received many comments on this issue, all in favor of the emissions
averaging approach discussed in the NODA to accommodate the different
emission characteristics in these stacks. Therefore, we today finalize
a provision to allow preheater or preheater-precalciner cement kilns
with dual stacks to average emissions on a flow-weighted basis to
demonstrate compliance with chlorine and metal emission standards.
Emission averaging to demonstrate compliance with the hydrocarbon/
carbon monoxide standard is not

[[Page 52971]]

needed at preheater and preheater-precalciner cement kilns with dual
stacks since today's rule requires these kilns to monitor hydrocarbon
or carbon monoxide in the bypass stack only.²⁷⁸ Emission
averaging for particulate matter is no longer needed since the format
of the standard (0.15 kg/Mg dry feed) implicitly requires the kiln to
consider mass emissions from both stacks to demonstrate compliance with
the emission standard. In addition, emission averaging for dioxin/furan
will not be allowed because cement kilns with dual stacks are expected
to control temperature in both air pollution control systems to comply
with the standard. No commenter stated that emission averaging was
needed for dioxin/furan.
---------------------------------------------------------------------------

\278\ New kilns at greenfield locations must also comply with a
main stack hydrocarbon standards. For these sources, emission
averaging for hydrocarbons would not appropriate because the purpose
of the main stack hydrocarbon standard is to control organic
hazardous air pollutants that originate from the raw material.
---------------------------------------------------------------------------

a. What Is the Average Methodology? In the May 1997 NODA, we did
not specify an averaging methodology. However, commenters suggested
that the following is an appropriate equation to calculate the flow-
weighted average concentration of a regulated constituent when
considering emissions from both stacks:
[GRAPHIC] [TIFF OMITTED] TR30SE99.029

Where:
Ctot = flow-weighted average concentration of the regulated
constituent
Cmain = average performance test concentration demonstrated
in the main stack
Cbypass = average performance test concentration
demonstrated in the bypass stack
Qmain = volumetric flowrate of main stack effluent gas
Qbypass = volumetric flowrate of bypass effluent gas

We agree that this equation properly calculates the flow-weighted
average concentration of the regulated constituent when considering
emissions from both stacks and it is adopted in today's rule.
b. What Emissions Testing and Compliance Demonstrations Are
Necessary? To use this emission averaging provision, you must
simultaneously conduct performance testing in both stacks during your
comprehensive performance test to compare emission levels of the
regulated constituents (as proposed). These emission data must be used
as inputs to the above equation to demonstrate compliance with the
emission standard.
You must develop operating parameter limits, and incorporate these
limits into your NOC, that ensures your emission concentrations, as
calculated with the above equation, do not exceed the emission
standards on a twelve-hour rolling average basis. These operating
parameters should limit the ratio of the bypass stack flowrate and
combined bypass and main stack flowrate such that the emission standard
is complied with on a twelve-hour rolling average basis. Whereas this
was not proposed, we conclude that this provision is necessary to
assure compliance with the standards since the ratio of stack gas
flowrate and bypass stack flowrate could deviate from the levels
demonstrated during the performance test.
c. What Notification Is Required? In the May 1997 NODA, we did not
discuss specific notification requirements. After careful
consideration, however, we determine that to use this emission
averaging provision, you must notify the Administrator of your intent
to do so in your performance test workplan. The performance test
workplan must include, at a minimum, information that describes your
proposed operating limits. You must document your use of this emission
averaging provision in your NOC and document the results of your
emissions averaging analysis after estimating the flow weighted average
emissions with the above equation. You must also incorporate into the
NOC the operating limits that ensures compliance with emission
standards on a twelve-hour rolling average basis.
G. What Are the Special Regulatory Provisions for Cement Kilns and
Lightweight Aggregate Kilns that Feed Hazardous Waste at a Location
Other Than the End Where Products Are Normally Discharged and Where
Fuels Are Normally Fired? (Sec. 63.1206(b)(12) and (b)(8)(ii))
As discussed in Part Four, Section IV.B., the Agency is allowing
you to comply with either a carbon monoxide or hydrocarbon standard.
However, we have concluded that this option to comply with either
standard should not apply if you operate a cement kiln or lightweight
aggregate kiln and feed hazardous waste at a location other than the
end where products are normally discharged and where fuels are normally
fired these other locations include, at the mid kiln or the cold, upper
end of the kiln. Consistent with the Boilers and Industrial Furnace
regulations (see Sec. 266.104(d)), we are today requiring you to comply
with the hydrocarbon standard, and are not giving you the option to
comply with the carbon monoxide standard, if you feed hazardous waste
in this manner. This is because we are concerned that hazardous waste
could be fired into a location such that nonmetal compounds in the
waste may be merely evaporated or thermally cracked to form pyrolysis
byproducts rather than be completely combusted.²⁷⁹ If this
occurs, there is the potential that little carbon monoxide will be
generated even though significant hydrocarbons are being emitted.
Carbon monoxide monitoring would thus not ensure that organic hazardous
air pollutant emissions are being properly controlled. We do not
anticipate this requirement to be overly burdensome, since it is a
current requirement of the Boilers and Industrial Furnace regulation.
---------------------------------------------------------------------------

\279\ See Final Rule, Burning of Hazardous Waste in Boilers and
Industrial Furances, February 21, 1991, 56 FR at 7158.
---------------------------------------------------------------------------

We have also concluded that it would not be appropriate for you to
comply with the hydrocarbon standard in the bypass duct if you operate
a cement kiln and feed hazardous waste into a location downstream of
your bypass sampling location relative to flue gas flow direction. Such
operation would result in hazardous waste combustion that would not be
monitored by a hydrocarbon monitor. Today's rulemaking thus requires
you to comply with the main stack hydrocarbon standard of 20 ppmv if
you feed hazardous waste in this manner. This is also consistent with
the Boilers and Industrial Furnace regulations, which do not allow you
to monitor hydrocarbons in the bypass duct if you operate a short kiln
and if you feed hazardous waste in the preheater or precalciner (see
Sec. 266.104(f)(1)).
In addition to the above requirements, if you operate a cement kiln
or

[[Page 52972]]

lightweight aggregate kiln and feed hazardous waste at a location other
than the end where products are normally discharged and where fuels are
normally fired, you are also required to demonstrate compliance with
the destruction and removal efficiency standard every five years as
opposed to a one-time destruction and removal demonstration We require
you to do this because the unique design and operation of such a waste
firing system necessitates a compliance demonstration for this standard
every five years (see previous discussion in part Four, Section
IV.A.3.).
H. What is the Alternative Particulate Matter Standard for
Incinerators? See Sec. 63.1206(b)(15).
As discussed in Part Four, Section II.A.2, today's rule establishes
a particulate matter standard of 0.015 gr/dscf for incinerators as a
surrogate to control nonenumerated metal hazardous air pollutants
(i.e., antimony, cobalt, manganese, nickel, selenium). Of course,
particulate matter air pollution control devices also exert control on
other metals (except highly volatile species such as mercury),
including the enumerated metals. (The enumerated metal hazardous air
pollutants are those CAA metal hazardous air pollutants regulated
directly via individual emission standards in today's rule, i.e.,
mercury, semivolatile metals, low volatile metals). A number of
commenters, primarily incinerator operators, assert that a particulate
matter standard should not be used as a surrogate control for metals in
situations where the particulate matter does not contain any metal
hazardous air pollutants (i.e., situations when the waste does not
contain any metals, except perhaps mercury and the resulting ash
contains only relatively benign ash or soot). These commenters argue
that the cost associated with reducing particulate matter levels below
0.015 gr/dscf would be excessive and that some type of alternative
standard (reflecting superior metal feedrate control) be created.
After considering these comments and another type of particulate
matter control technology, we conclude that it is appropriate to offer
an alternative particulate matter standard of 0.03 gr/dscf for
incinerators that have de minimis levels of hazardous air pollutant
metals in their feedstreams, and we have adopted a petition process to
allow incinerators to seek this alternative standard. An alternative
particulate matter standard is within the scope of our overall preamble
discussions of the control of particulate matter and metal emissions,
the ways in which the Agency was considering feedrate as part of its
MACT analysis, our approaches to enumerated and non-enumerated CAA
hazardous air pollutant metals, and the presentation of options for
compliance testing when only de minimis levels of metals are present.
1. Why is this Alternative Particulate Matter Standard Appropriate
under MACT?
An alternative particulate matter floor level of 0.030 gr/dscf is
appropriate for an incinerator that can demonstrate it has de minimis
levels of CAA hazardous air pollutant metals (except mercury), as
defined below, in its feedstreams. As discussed in other portions of
this preamble and in our technical background documents for this
rulemaking, control of metals (other than mercury) is a function, in a
practical sense, of both the feedrate of those metals into the
combustion device as well as the design, operation, and maintenance of
a source's air pollution control devices for particulate matter. Given
the intertwined relationship between these two factors, the Agency has
concluded that a particulate matter floor control level of 0.015 gr/
dscf is not warranted for sources using superior feedrate control (i.e.
beyond MACT) to reduce metal emissions, which in this case would be
shown by having non-detectable levels of metals in their feedstreams
(discussed in more detail below).²⁸⁰
---------------------------------------------------------------------------

\280\ We do not require you to document that your feedstreams
have de minimis mercury levels to qualify for this alternative
standard because mercury is a volatile metal and is generally not
controlled with particulate matter control technologies.
---------------------------------------------------------------------------

We also conclude that the floor control for this alternative
standard is the use of a venturi scrubber or the use of the same, but
less sophisticated, particulate matter control technologies that were
established for the 0.015 gr/dscf standard.²⁸¹ These floor
technologies, including venturi scrubbers, were the basis of our
particulate matter floor standard of 0.029 gr/dscf which was published
for comment in the May 1997 NODA. See 62 FR at 24221. Although we have
since determined that 0.015 gr/dscf is a technically achievable and
appropriate MACT floor control level for incinerators based on a suite
of technologies that does not include venturi scrubbers, we conclude
that an alternative floor level of 0.030 gr/dscf that includes venturi
scrubbers in the floor is appropriate for sources using superior metal
feedrate control. Put another way, we view the average of the 12
percent best performing incinerators as including incinerators with
venturi scrubbers when the incinerator is exercising beyond-MACT feed
control of hazardous air pollutant metals.²⁸² We also note
that the final rule for medical waste incinerators establishes a
particulate matter standard of 0.030 gr/dscf for medium sized existing
sources and small new sources that is based on medium efficiency
venturi scrubbers. See 62 FR at 48348. The alternative floor level of
0.030 gr/dscf that is adopted in this final rulemaking is appropriate
when we include venturi scrubbers as an alternative floor control
technology when superior feed rate control is being
employed.²⁸³
---------------------------------------------------------------------------

\281\ As discussed in Part Four, Section VI.C.4.a, particulate
matter floor control for hazardous waste incinerators is defined as
the use of either fabric filters, electrostatic precipitators (dry
or wet), or ionizing wet scrubbers (sometimes in combination with
venturi, packed bed, or spray tower scrubbers) that achieve
particulate matter emission levels of 0.015 gr/dscf or less.
\282\ See Final Technical Support Document, Volume 3, Chapter
Four, July, 1999, for further discussion.
\283\ The cement kilns and lightweight aggregate kilns that are
also covered by today's final rule have feedrates of metals far
above any de minimis threshold. See Final Technical Support
Document, Volume 3, Chapter Four, July, 1999, for further
discussion. Therefore, in light of the commenters requesting
alternative standards and in light of the feedstream levels of
metals going into the kilns, we have elected to offer an alternative
particulate matter standard only to incinerators.
---------------------------------------------------------------------------

Particulate matter control below 0.030 gr/dscf is still necessary
to control metal emissions at sources with de minimis levels of
hazardous air pollutant metals in their feedstreams for several
reasons. Even if an incinerator obtains non-detect analytical results
for one or more metals in its feedstream, this does not conclusively
prove that metals are absent. Rather, all that such laboratory results
mean is that the metals are not contained in the feedstream above the
detection limit used in the analysis. This detection limit may be low
but it can also be fairly high depending on the waste matrix. As
previously discussed in Part Five, Section X.C.1, commenters have
indicated that feedstream metal detection limits are highly dependent
on the feedstream matrix.
Given that our prerequisite for the alternative standard is that de
minimis levels of metals are present, we must take into account this
phenomenon of matrix-dependent detection limits. We are unwilling
simply to allow facilities upon a showing of non-detectable levels of
metals to avoid particulate matter controls entirely, especially given
the complementary controls in practice provided by both feedrate
control and

[[Page 52973]]

particulate matter air pollution control devices. On the other hand, it
would be overly narrow to give essentially no credit for superior
feedrate control (shown by non-detectable levels of metals) by
requiring these incinerators to meet 0.015 gr/dscf. It appears,
therefore, to be an appropriate balance to allow facilities with non-
detectable levels of metals (other than mercury) to meet a standard of
0.030 gr/dscf. This will assure control reflecting performance of the
best performing plants that use superior (i.e., beyond MACT) feedrate
control, especially in the event that detection limits for a particular
waste matrix are unusually high. Because we are moving to a Performance
Based Measurement System (PBMS) we cannot rely upon previously approved
EPA standard methods as a means to predict detection levels in various
matrices. Therefore, we are retaining a particulate matter standard
0.030 gr/dscf to offset the potential for high detection limits.
2. How Do I Demonstrate Eligibility for the Alternative Standard?
Although we adopt a particulate matter standard as a surrogate to
control nonenumerated metal hazardous air pollutants, particulate
matter control is an integral part of the semivolatile and low volatile
metal emission standards as well, as discussed above. See Part Four,
Section II.A.1, for further discussion. We therefore conclude that you
must document that not only the nonenumerated metals meet the de
minimis criteria explained below, but that the semivolatile and low
volatile metals do as well. This provides assurance that superior
feedrate control is being achieved for all hazardous air pollutant
metals, which in turn allows us to provide you with the opportunity to
use the alternative particulate matter standard.
To demonstrate eligibility, you must document that you meet two
qualification requirements. First, you must document that your
feedstreams do not contain detectable levels of CAA hazardous air
pollutant metals, apart from mercury (i.e., antimony, cobalt,
manganese, nickel, selenium, lead, cadmium, chromium, arsenic and
beryllium). This requirement is necessary to ensure that you have de
minimis levels of metals in your feedstreams, and assures us that you
are using superior feedrate control. You must conduct feedstream
analyses at least annually to document that your feedstreams do not
contain detectable levels of these metals. Permitting officials may, on
a site-specific basis, require more frequent feedstream analyses to
better ensure that you comply with this eligibility requirement.
Second, you must document that your calculated uncontrolled metal
emissions, i.e., no system removal efficiency, are below the numerical
semivolatile and low volatile metal emission standards. When
calculating these uncontrolled emissions, you must assume metals are
present at one-half the detection limit and are categorized into their
appropriate volatility grouping for purposes of this requirement. The
one-half detection limit assumption provides a relatively, but not
overly, conservative way assuring that de minimis determinations are
not given to sources with very high detection limits.
For example, the combined uncontrolled emissions for lead, cadmium
and selenium, when assuming these metals are present at one-half the
detection limit, must be below 240 g/dscm. The combined
uncontrolled emissions for antimony, cobalt, manganese, nickel,
chromium, arsenic and beryllium, when assuming these metals are present
at one-half the detection limit, must be below 97 g/dscm. We
require this second eligibility requirement because (1) it ensures you
have de minimis levels of metals in your feedstreams even though metals
can be present at levels below the detection limit, and (2) it
encourages you to obtain reasonable detection limits.
3. What Is the Process for the Alternative Standard Petition?
If you are seeking this alternative particulate matter standard,
you must submit a petition request to the Administrator, or authorized
regulatory Agency, that includes the documentation discussed above. You
will not be allowed to operate under this alternative standard until
the Administrator determines that you meet the above qualification
requirements. Although we are not requiring that you include this
petition as part of the comprehensive performance test workplan, we
strongly recommend that you do so. This approach has several
advantages: (1) It will clarify which PM standard you are complying
with as of your documentation of compliance, and avoid potential
confusion about your state of compliance; (2) it will help ensure that
the planned performance tests cover all of the relevant parameters and
standards and will facilitate interpretation of performance test
results; (3) it will help avoid costs of having to conduct a separate
performance test to show compliance with the alternative standard,
which would include re-testing and re-establishment of many of the same
parameters as would be covered in the initial comprehensive performance
test; and (4) it will help maximize the time that the regulatory agency
needs to evaluate your demonstration of the prerequisite, non-detect
levels of metals in your feed, including the time needed for you to
respond to any additional information that may be requested by the
agency. Agency approval of a comprehensive performance test workplan
that also includes this petition request will be deemed as approval for
you to operate pursuant to this alternative standard. In our
implementation of today's final rule, we will address as appropriate
various considerations related to processing these petitions, including
the timing of the submittal, review and approval. We fully expect that
Agency permit officials will act expeditiously on these petitions so
that both the source and the reviewing official know what particulate
matter level the comprehensive performance test must show is being
achieved.

XI. What Are the Permitting Requirements for Sources Subject to this
Rule?

As indicated in Part One, we intend the requirements of this rule
to meet our obligations for hazardous waste combustor air emission
standards under two environmental statutes, the Clean Air Act and the
Resource Conservation and Recovery Act. The overlapping air emission
requirements of these two statutes have historically resulted in some
duplication of effort. In developing a permitting scheme that
accommodates the requirements of both statutes, with regard to the new
air emissions limitations and standards being promulgated in this rule,
our goal is to avoid any such duplication to the extent possible. This
goal is consistent with the RCRA statutory directive of section
1006(b)(1) to ``integrate all provisions of (RCRA) for purposes of
administration and enforcement and (* * *) avoid duplication, to the
maximum extent practicable, with the appropriate provisions of the
Clean Air Act.'' ²⁸⁴ It also is consistent with our
objectives to streamline requirements and follow principles that
promote ``good government.''
---------------------------------------------------------------------------

\284\ See also CAA section 112(n)(7) (requirements of section
112 should be consistent with those of RCRA Subtitle C to the
maximum extent practicable).

---------------------------------------------------------------------------

[[Page 52974]]

A. What Is the Approach to Permitting in this Rule?
1. In General What Was Proposed and What Was Commenters' Reaction?
In the April 1996 NPRM, we proposed placing the MACT air emissions
standards in the CAA regulations at 40 CFR part 63 and proposed to
reference the standards in the RCRA regulations at 40 CFR parts 264 and
266. (see 61 FR 17451, April 19, 1996). At that time, we believed that
placing the standards in both the CAA and RCRA regulations would
provide maximum flexibility to regulatory authorities at the Regional,
State, or local levels to coordinate permitting and enforcement
activities in the manner most appropriate for their individual
circumstances.²⁸⁵ We also believed that this approach would
alleviate the potential for duplicative requirements across permitting
programs.
---------------------------------------------------------------------------

\285\ When referring to permitting under the CAA, we mean
operating permits under title V of the CAA. The regulations
governing state and federal title V permit programs are codified in
40 CFR parts 70 and 71, respectively.
---------------------------------------------------------------------------

In addition, we presented two examples of ways for permitting
hazardous waste combustors subject to the new MACT standards. These
examples reflected, in part, the proposed approach of incorporating the
new MACT standards into both RCRA and CAA implementing
regulations.²⁸⁶ (See 61 FR 17451, April 19, 1996.) In the
first example, the two permitting programs would work together to issue
one permit, under joint CAA and RCRA authority, that would meet all the
requirements of both programs. In the second example, the two
permitting programs would coordinate their efforts with each program
issuing a separate permit; the items common to both (e.g., the air
emissions standards) would be included in one permit and incorporated
by reference into the other permit.
---------------------------------------------------------------------------

\286\ The possibility of issuing only one EPA permit under
either CAA or RCRA authority, and the ensuing legal barriers
rendering that approach infeasible, also were discussed in the
preamble for the proposed rule (61 FR 17451, April 19, 1996).
---------------------------------------------------------------------------

Comments on the April 1996 NPRM expressed widespread support for
providing flexibility for regulatory agencies to implement common sense
permitting schemes that fit their organization and resources. However,
commenters disagreed as to which approach would best provide such
flexibility. A few commenters thought that the April 1996 NPRM
approach, placing the standards in both CAA and RCRA regulations, would
both provide flexibility to choose which program would issue permits
and therefore avoid duplication.
On the other hand, we received several comments challenging our
assumption that placement of the standards in both CAA and RCRA
regulations would optimize flexibility for regulatory agencies. These
commenters believed that the regulatory agencies would be, in fact,
more limited. They noted that both the RCRA and CAA programs would be
responsible for incorporating the standards, to some extent, into their
permits, even if just by referencing the other. Commenters also were
concerned with the potential for conflicting conditions between the two
permits, particularly with regard to testing, monitoring, and
certification requirements. In addition, they felt that the conditions
common to both permits might be subject to separate decision-making
processes. For example, they might potentially be subject to two
different administrative or judicial appeals procedures and two permit
modification procedures. If this happened, the Agency would not achieve
its stated objective of avoiding duplication between the two programs.
Additionally, our example pointing to close coordination between
programs to avoid duplication was countered by commenters examples
where such coordination has not occurred, either due to logistical
problems within regulatory agencies or to differences in administrative
processes between the two programs.
Commenters also expressed concern about the potential for
enforcement of the same requirement under two different statutes that
they believed the proposed approach would create. Since the
requirements would have to be incorporated into both RCRA permits and
CAA title V permits, sources would have to comply with both. Although
we stated in the proposal that we did not expect to take enforcement
action under both permits (see 62 FR 17452), commenters noted that this
would not restrain State or local authorities from initiating dual
enforcement actions. In addition, commenters pointed out that they
would be vulnerable to citizen suits under both statutes.
The majority of the commenters voiced a desire for the Agency to
avoid duplicate requirements or redundant processes. We received
several suggestions for alternative approaches, which can be grouped in
three ways: (1) Requiring regulatory agencies to develop a separate
permitting program to cover elements common to both CAA and RCRA (i.e.,
air emissions and related operating requirements) while maintaining
separate permits for the other elements; (2) Developing a single multi-
media permit to cover all RCRA and CAA requirements applicable to
hazardous waste combustors; and (3) placing the standards only in CAA
regulations and incorporation only into the title V permits.
The first alternative, i.e., requiring a separate permitting
program for air emissions and related parameters, is a very different
approach that would likely require the development of more new
regulations. However, duplication may be avoided without promulgation
of an ``independent'' permitting scheme just for the elements common to
both RCRA and CAA programs. Other alternatives would not involve the
time and effort needed to craft and adopt a new regulatory scheme, such
as that suggested.
We believe that the second alternative, pursuing multi-media
permits, had some merit. As commenters pointed out, the Agency's
Permits Improvement Team expressed support for multimedia permits in
its ``Concept Paper.'' The Permits Improvement Team also acknowledged,
however, that true multimedia permits have been difficult to develop.
We still support multimedia permitting, and this rule does not preclude
this approach. Nevertheless, we do not believe that, at this point, we
can rely on multimedia permitting as an overall approach to
implementing this rule. Some States have successfully piloted multi-
media permitting or implemented ``one-stop'' permits that address both
RCRA and CAA requirements. We encourage States to continue these
efforts and to apply them to hazardous waste combustor permitting to
the extent possible. Even for States that do not currently pursue
multimedia or one-stop permits, this rule presents unique opportunities
to start moving in that direction.
The third alternative had a couple of variations. The
straightforward version was simply to place the MACT air emission
standards in the CAA regulations, incorporate them into title V
permits, and continue to issue RCRA permits for other RCRA-regulated
aspects of the combustion unit, as well as of the rest of the facility
(e.g., corrective action, general facility standards, other combustor-
specific concerns such as materials handling, risk-based emissions
limits and operating requirements, as appropriate, and other hazardous
waste management units). A variation of this was to develop a RCRA
permit-by-rule provision to defer to title V permits. The
straightforward approach was favored by the majority of the commenters.
Some offered, as further support for this

[[Page 52975]]

position, a reference to the recommendation put forth by the Permit
Improvement Team's Alternatives to Individual Permits Task Force that
called for permitting air emissions from hazardous waste combustors
under the CAA. The variation of developing a RCRA permit-by-rule
provision is not as responsive to commenters' concerns because, among
other things, that approach would not avoid the potential for dual
enforcement. Although the permit-by-rule has the effect of deferring to
the title V permit, the facility is still considered to have a RCRA
permit for the combustor's air emissions.
2. What Permitting Approach Is Adopted in Today's Rule?
We found the arguments for the straightforward approach (i.e.,
placing the standards only in the CAA regulations and relying on the
title V permitting program) persuasive. Based on the comments we
received, and our subsequent analysis, we narrowed our options for how
to permit hazardous waste combustors subject to the new MACT standards
and elaborated on our preferred approach in the May 1997 NODA (see 62
FR 24249). In the NODA, we described an approach to place the MACT
emissions standards only in the CAA regulations at 40 CFR part 63
Subpart EEE, and rely on implementation through the air program,
including operating permit programs developed under title V. Under this
approach, which we are adopting in today's final rule, MACT air
emissions and related operating requirements are to be included in
title V permits; RCRA permits will continue to be required for all
other aspects of the combustion unit and the facility that are governed
by RCRA (e.g., corrective action, general facility standards, other
combustor-specific concerns such as materials handling, risk-based
emissions limits and operating requirements, as appropriate, and other
hazardous waste management units).
Placement of the emissions standards solely in part 63 appears to
be the most feasible way to avoid duplicative permitting requirements.
We agree with the commenters' views that placement of the standards in
both RCRA and CAA regulations would require both permits to address air
emissions. Permitting authorities would not be able to choose which
program would be responsible for implementing the requirements. Placing
the standards in both sets of regulations would obligate both programs
to address the standards in permits issued under their respective
authorities. Simply put, permitting authorities would not be free to
incorporate the new standards into either CAA title V permits or RCRA
permits; rather, they would need to incorporate the new standards, to
some degree, into both permits.²⁸⁷ Having determined that
placement of the standards in both sets of regulations is not
desirable, we revisited the question of whether one program could defer
to the other. The CAA does not provide authority to defer to other
environmental statutes,²⁸⁸ so we could not place the MACT
standards solely in RCRA regulations, which would have consequently
allowed them to be incorporated only into a RCRA permit. On the other
hand, RCRA does provide authority to forego RCRA emissions standards in
favor of MACT standards imposed under the CAA. As stated above in Part
One, Section I, under the authority of RCRA section 3004(a), it is
appropriate to eliminate these RCRA standards because they would only
be duplicative and so are no longer necessary to protect human health
and the environment. Also as discussed there, RCRA section 1006(b)
provides further authority for the Administrator to eliminate the
existing RCRA air emissions standards in order to avoid duplication
with the new MACT standards. Thus, we use our authority to defer RCRA
controls on the air emissions to the part 63 MACT standards, which
ultimately are incorporated into title V permits issued under the CAA.
---------------------------------------------------------------------------

\287\ As discussed earlier, states may be able to develop
combined permits that address both RCRA and CAA requirements. Such
permits would have to cite the appropriate authority (CAA or RCRA)
for each condition, and have to be signed by the appropriate
officials of each program. Permit conditions would continue to be
enforced under their respective authorities as well.
\288\ Although CAA section 112(n)(7) is directed at harmonizing
requirements with RCRA, it does not provide a jurisdictional basis
for deferral (i.e., nonpromulgation of mandated section 112(d) MACT
standards in light of the existence of RCRA standards).
---------------------------------------------------------------------------

The majority of the comments received following publication of the
May 1997 NODA supported our preferred approach to permitting the
hazardous waste combustors. Several commenters expressed appreciation
for this effort, and concluded that our approach would avoid
duplication and have the RCRA and title V permits work to complement
each other rather than potentially contradict each other. Although
sources will still have two permits, the scope and subject matter of
each will be distinguishable. The title V permit will focus on the
operation of the combustion unit (e.g., air emissions and related
parameters) while the RCRA permit will continue to focus on basic
hazardous waste management at the facility (e.g., general facility
standards, corrective action, other units, and so on). The only time
there might be conditions in both RCRA and title V permits that address
the same hazardous waste combustor operating requirements and limits is
when there is a need to impose more stringent risk-based conditions,
e.g., under RCRA ``omnibus'' authority, in the RCRA permit. The RCRA
permitting authority would add terms and conditions based on the
omnibus clause only if it found, at a specific facility, that the MACT
standards were not sufficient to protect human health or the
environment. This issue is discussed in greater detail in Part III,
Section IV (RCRA Decision Process). In those limited cases, sources and
permitting agencies may agree to identify the RCRA limit in the title V
permit. Since one goal of the title V program is to clarify a source's
compliance obligations, it will be beneficial, and convenient, to
acknowledge the existence of more stringent limits or operating
conditions derived from RCRA authority for the source in the title V
permit, even though the requirements would not reflect CAA
requirements. We strongly encourage Regional, State, and local
permitting authorities to take advantage of this beneficial option.
Some commenters continued to maintain that flexibility to choose
which program would permit air emissions would only be provided if we
were to promulgate the standards in both CAA and RCRA regulations. They
reiterated the position they had taken in their comments on the initial
proposal that this approach would not result in duplication across the
programs; they discounted concerns over duplicative requirements or
dual enforcement scenarios by saying that it was basically not in a
permitting authority's best interests to issue duplicate permits. We
found the contrary, that placement of the standards in both sets of
regulations does not provide flexibility for a regulatory agency to
choose one permit program or another. Such an approach would obligate
both permits to cover air emissions and related operating requirements.
This result does not achieve our or the commenters' objective of
avoiding duplication across programs. Although the actual burden on
permit writers may not be significant if, for example, the title V
permit were to just cross-reference the appropriate sections of the
RCRA permit, the requirements would still be enforceable under both
vehicles, and would go through dual administrative processes. As
mentioned above, EPA would like to

[[Page 52976]]

avoid this type of dual enforcement and dual process scenario in
implementing the new standards.
3. What Considerations Were Made for Ease of Implementation?
Our approach in the final rule does not limit the options available
to state permitting authorities for implementing the new standards. The
primary concern about which program (RCRA or CAA) assumes lead
responsibility for administering air emissions requirements appears to
revolve around resource issues. The RCRA program has been the lead
program for permitting hazardous waste combustors for many years,
consequently, RCRA program staff have developed a great deal of
expertise in this area. They are familiar with source owners and
operators, the combustion units, and special considerations associated
with permitting hazardous waste combustion activities. Some commenters
are concerned that by deferring regulation of air emissions standards
to the CAA, that expertise will no longer be available. They express
doubt about the ability of air toxics implementation programs and title
V programs to take on these sources, given the complexity of hazardous
waste combustor operations and the volume of title V permits that need
to be issued over the next several years.²⁸⁹
---------------------------------------------------------------------------

\289\ Title V permits are required for many more sources than
those subject to the HWC MACT standards. Currently, there are
approximately 20,000 sources that are subject to title V; there are
only about HWCs subject to today's rule.
---------------------------------------------------------------------------

In response to these comments, we note that many State Air programs
currently play key roles in permitting hazardous waste combustors under
RCRA. Furthermore, States may find that much of the expertise used to
regulate other air sources is directly applicable to regulating the
hazardous waste combustor sources subject to the new MACT standards,
and that the resources in their air programs are sufficient to handle
these additional sources. If, however, a State shares commenters'
concerns that its air program, as it currently exists, may not be able
to take on these sources, the State may continue using the resources
and expertise of its RCRA program even though the new standards are
being promulgated as part of the CAA regulations.
In the May 1997 NODA, we discussed the flexibility afforded to
States by codifying the standards under only one statute (see 62 FR
24246). Two potential options were described in the NODA for how this
might be achieved: (1) A State could simply have its RCRA staff
implement the hazardous waste combustor MACT standards; or (2) a State
could formally incorporate the standards into its State RCRA program.
In response to the NODA, some State environmental agencies commented
that, as a matter of State law, they would not be able to incorporate
the new standards into their authorized hazardous waste programs unless
they are included in federal RCRA regulations. We acknowledge,
therefore, that some States may not be able to pursue the second
option. In any case, we recommend against this option because, as
discussed below, it would perpetuate having duplication between two
permits. The first option would, however, still be feasible. For
example, the States could explore the flexibility provided through
Performance Partnership Agreements ²⁹⁰ if they would like to
have their RCRA program staff continue their work with the hazardous
waste combustors.
---------------------------------------------------------------------------

\290\ Within negotiated agreements, there is flexibility in
Performance Partnership Grants to strategically move funds, and
flexibility in Performance Partnership Agreements found in the
National Environmental Performance Partnership System to
strategically integrate programs.
---------------------------------------------------------------------------

If a State chooses to use either of the above options to continue
applying RCRA expertise to hazardous waste combustors, we anticipate
that RCRA program staff would be responsible for many of the
implementation activities, such as reviewing documents submitted by the
source (e.g., the Notice of Intent to Comply, the progress report, and
the performance test plan), and working with the source to resolve any
differences (e.g., on anticipated operating requirements or on results
of comprehensive performance tests).
Where the process issues would start to diverge between the two
options is at the actual permitting stage. Under the first option (RCRA
staff implementing CAA regulations), the standards would be
incorporated only into title V permits. Title V permits cover a wide
range of applicable requirements under the CAA; the hazardous waste
combustor MACT standards are likely to be just one piece.²⁹¹
We believe that the RCRA permit writer would draft the hazardous waste
combustor portion of the title V permit, and would coordinate with the
title V permit writer in the CAA program who has responsibility for the
source's overall permit to ensure that the hazardous waste combustor
portion is properly incorporated. In short, the RCRA permit writer
would simply be developing a component of a title V permit instead of
developing a component of a RCRA permit. State permitting authorities
that wish to continue using their RCRA expertise will undoubtedly
explore this approach.
---------------------------------------------------------------------------

\291\ If the HWC MACT standards are the only applicable CAA
requirements, however, then there would be no other components of a
title V permit for the source.
---------------------------------------------------------------------------

If a State pursues the second option of incorporating the new
hazardous waste combustor MACT standards into its State RCRA program,
there may still be a need to incorporate the standards into both title
V and RCRA permits. The CAA does not provide authority to defer title V
permitting to other environmental programs. Thus, the source would
still be subject to title V requirements (i.e., a RCRA permit could not
``replace'' a title V permit). Furthermore, an EPA Region or a State
who chooses to obtain authorization for the hazardous waste combustor
MACT standards under RCRA would also have to start implementing the new
standards under CAA authority (including title V permitting
requirements) even as the State begins efforts to incorporate the
standards into its State RCRA program.
Although close cooperation between the RCRA and title V permit
writers could minimize duplicative efforts in developing permits and
avoid conflicting conditions in the two permits (for example, by
putting the conditions in one permit and just referencing them in the
other), this approach still results in the potential for enforcement
and citizen suits under both permits. ²⁹² As discussed
above, we intend to avoid duplicate permitting and enforcement
scenarios for hazardous waste combustor MACT standards; thus, we
strongly encourage States that choose to pursue this approach to
develop implementation schemes that minimize the potential for such
duplication to the extent practicable.
---------------------------------------------------------------------------

\292\ Some States have successfully issued ``one-stop''
multimedia permits which include provisions from both the CAA and
RCRA programs in a single permit. However, it is EPA's understanding
that these permits cite both the RCRA and CAA authority; thus, the
potential for enforcement under both statutes still remains.
---------------------------------------------------------------------------

B. What Is the Applicability of the Title V and RCRA Permitting
Requirements?
This section briefly summarizes the applicability of both title V
and RCRA permitting requirements under the permitting scheme discussed
in Section XI. A. above. It also discusses the relationship of this
permitting scheme to both the proposed revisions to combustion
permitting procedures from June 1994 and to the RCRA preapplication
meeting requirements. Our decision to subject hazardous waste
combustors that are considered area

[[Continued on page 52977]]

Notices For
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2003
2002
2001
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1996
1995
1994

[[pp. 52927-52976]] NESHAPS: Final Standards for Hazardous Air Pollutants for

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