[Federal Register Volume 72, Number 187 (Thursday, September 27, 2007)]
[Proposed Rules]
[Pages 54875-54888]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: E7-19097]


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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 63

[EPA-HQ-OAR-2004-0022; FRL-8474-2]
RIN 2050-AG29


NESHAP: National Emission Standards for Hazardous Air Pollutants: 
Standards for Hazardous Waste Combustors

AGENCY: Environmental Protection Agency (EPA).

ACTION: Solicitation of comment on legal analysis.

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SUMMARY: On October 12, 2005, pursuant to section 112(d) of the Clean 
Air Act, EPA issued national emission standards for hazardous air 
pollutants (NESHAP) emitted by various types of hazardous waste 
combusters. EPA subsequently granted reconsideration petitions relating 
to certain issues presented by the rules. 71 FR 14665, 52564, but has 
not yet issued a final determination on reconsideration. Following the 
close of the comment period on the proposed reconsideration rule, the 
United States Court of Appeals for the District of Columbia Circuit has 
issued several opinions construing section 112 (d) of the Clean Air 
Act, and one of those opinions has called into question the legality of 
some of the standards for hazardous waste combusters. This notice 
discusses the standards that EPA promulgated in October 2005, and 
specifically identifies which standards EPA believes are consistent 
with the Act and caselaw, and which standards are not and need to be 
reexamined through a subsequent rulemaking. With respect to those 
standards EPA intends to retain, this notice indicates the portions of 
the rationale upon which EPA intends to rely, and which portions EPA 
would no longer rely upon as a justification for the October 2005 
standards. EPA is seeking public comment on this analysis. EPA has also 
placed edited versions of various support documents in the public 
docket, edited to remove portions of the rationale on which EPA no 
longer plans to rely, and seeks public comment on these edits.

DATES: Comments must be received on or before October 18, 2007.

ADDRESSES: Submit your comments, identified by Docket ID No. EPA-HQ-
OAR-2004-0022, by one of the following methods:
     www.regulations.gov: Follow the on-line instructions for 
submitting comments.
     E-mail: [email protected].
     Fax: 202-566-1741.
     Mail: U.S. Postal Service, send comments to: Air and 
Radiation Docket (2822T), Docket ID No. EPA-HQ-OAR-2004-0022, U.S. 
Environmental Protection Agency, 1200 Pennsylvania Avenue, NW., 
Washington, DC 20460. Please include a total of two copies.
     Hand Delivery: In person or by courier, deliver comments 
to: HQ EPA Docket Center, Public Reading Room, EPA West, Room 3334, 
1301 Constitution Avenue, NW., Washington, DC 20004. Such deliveries 
are only accepted during the Docket's normal hours of operation, and 
special arrangements should be made for deliveries of boxed 
information. Please include a total of two copies.
    Instructions: Direct your comments to Docket ID No. EPA-HQ-OAR-
2004-0022. The EPA's policy is that all comments received will be 
included in the public docket without change and may be made available 
online at www.regulations.gov, including any personal information 
provided, unless the comment includes information claimed to be 
Confidential Business Information (CBI) or other information the 
disclosure of which is restricted by

[[Page 54876]]

statute. Do not submit information that you consider to be CBI or 
otherwise protected through www.regulations.gov or e-mail. The 
www.regulations.gov Web site is an ``anonymous access'' system, which 
means EPA will not know your identity or contact information unless you 
provide it in the body of your comment. If you send an e-mail comment 
directly to EPA without going through www.regulations.gov, your e-mail 
address will be automatically captured and included as part of the 
comment that is placed in the public docket and made available on the 
Internet. If you submit an electronic comment, EPA recommends that you 
include your name and other contact information in the body of your 
comment and with any disk or CD-ROM you submit. If EPA cannot read your 
comment due to technical difficulties and cannot contact you for 
clarification, EPA may not be able to consider your comment. Electronic 
files should avoid the use of special characters, any form of 
encryption, and be free of any defects or viruses. For additional 
information about EPA's public docket visit the EPA Docket Center 
homepage at http://www.epa.gov/epahome/dockets.htm.
    Docket: All documents in the docket are listed in the 
www.regulations.gov index. Although listed in the index, some 
information is not publicly available, e.g., CBI or other information 
the disclosure of which is restricted by statute. Certain other 
material, such as copyrighted material, will be publicly available only 
in hard copy. Publicly available docket materials are available either 
electronically in www.regulations.gov or in hard copy at the HQ EPA 
Docket Center, Public Reading Room, EPA West, Room 3334, 1301 
Constitution Avenue, NW., Washington, DC 20004. The Public Reading Room 
is open from 8:30 a.m. to 4:30 p.m., Monday through Friday, excluding 
legal holidays. The telephone number for the Public Reading Room is 
(202) 566-1744, and the telephone number for the HQ EPA Docket Center 
is (202) 566-1742. A reasonable fee may be charged for copying docket 
materials.

FOR FURTHER INFORMATION CONTACT: For more information on this notice, 
contact Frank Behan at (703) 308-8476, or [email protected], Office 
of Solid Waste (5302P), U.S. Environmental Protection Agency, 1200 
Pennsylvania Ave., NW., Washington, DC 20460.

SUPPLEMENTARY INFORMATION: Entities Potentially Affected by this 
Action. Categories and entities potentially affected by this action 
include:

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                                      NAICS      Potentially affected
              Category               code\a\           entities
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Petroleum and coal products              324  Any entity that combusts
 manufacturing.                                hazardous waste as
                                               defined in the final
                                               rule.
Chemical manufacturing.............      325
Cement and concrete product             3273
 manufacturing.
Other nonmetallic mineral product       3279
 manufacturing.
Waste treatment and disposal.......     5622
Remediation and other waste             5629
 management services.
------------------------------------------------------------------------
\a\ North American Industry Classification System.

    This table is not intended to be exhaustive, but rather provides a 
guide for readers regarding entities likely to be impacted by this 
action. This table lists examples of the types of entities EPA is now 
aware could potentially be regulated by this action. Other types of 
entities not listed could also be affected. To determine whether your 
facility, company, business, organization, etc., is affected by this 
action, you should examine the applicability criteria in 40 CFR 
63.1200.\1\ If you have any questions regarding the applicability of 
this action to a particular entity, consult the person listed in the 
preceding FOR FURTHER INFORMATION CONTACT section.
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    \1\ Unless otherwise noted, all regulatory references in this 
notice are to 40 CFR.
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    How Do I Obtain a Copy of this Document and Other Related 
Information? In addition to being available in the docket, an 
electronic copy of today's proposed rule will also be available on the 
World Wide Web (WWW). Following the Administrator's signature, a copy 
of this document may be posted on the WWW at http://www.epa.gov/hwcmact. This Web site also provides other information related to the 
NESHAP for hazardous waste combustors including the NESHAP issued on 
October 12, 2005 (70 FR 59402) and the two petition for reconsideration 
notices published on March 23, 2006 (71 FR 14665) and September 6, 2006 
(71 FR 52624).
    Preparation of Comments. Do not submit this information to EPA 
through www.regulations.gov or e-mail. Clearly mark the part or all of 
the information that you claim to be CBI. For CBI information in a disk 
or CD-ROM that you mail to EPA, mark the outside of the disk or CD-ROM 
as CBI and then identify electronically within the disk or CD-ROM the 
specific information that is claimed as CBI. In addition to one 
complete version of the comment that includes information claimed as 
CBI, a copy of the comment that does not contain the information 
claimed as CBI must be submitted for inclusion in the public docket. 
Information so marked will not be disclosed except in accordance with 
procedures set forth in 40 CFR part 2. Send or deliver information 
identified as CBI to only the following address: Ms. LaShan Haynes, 
RCRA Document Control Officer, EPA (Mail Code 5305P), Attention Docket 
ID No. EPA-HQ-OAR-2004-0022, 1200 Pennsylvania Avenue, Washington DC, 
20460. Clearly mark the part or all of the information that you claim 
to be CBI.
    Tips for Preparing Your Comments. When submitting comments, 
remember to:
     Identify the rulemaking by docket number and other 
identifying information (subject heading, Federal Register date and 
page number).
     Follow directions--The agency may ask you to respond to 
specific questions or organize comments by referencing a Code of 
Federal Regulations (CFR) part or section number.
     Explain why you agree or disagree; suggest alternatives 
and substitute language for your requested changes.
     Describe any assumptions and provide any technical 
information and/or data that you used.
     If you estimate potential costs or burdens, explain how 
you arrived at your estimate in sufficient detail to allow it to be 
reproduced.
     Provide specific examples to illustrate your concerns, and 
suggest alternatives.
     Explain your views as clearly as possible.
     Make sure to submit your comments by the comment period 
deadline identified.
    Organization of this Document. The information presented in this 
notice is organized as follows:


[[Page 54877]]


I. Background
II. Consideration of Variability in Establishing MACT Floors
III. Discussion of Individual Standards
    A. Standards for Particulate Matter
    1. Standards for Incinerator, Cement Kilns, Lightweight 
Aggregate Kilns, and Solid Fuel Boilers
    2. Standards for Liquid Fuel Boilers
    B. Standards for Semivolatile Metals and Low Volatility Metals
    1. Methodology to Establish Floor Levels
    2. Alternatives to the Particulate Matter Standard for 
Incinerators, Liquid Fuel Boilers, and Solid Fuel Boilers
    3. Alternative Mercury, Semivolatile Metals, Low Volatile 
Metals, and Total Chlorine Standards for Cement Kilns and 
Lightweight Aggregate Kilns
    4. Alternative Mercury Standards for Cement Kilns and 
Lightweight Aggregate Kilns Under the Interim Standards
    C. Standards for Total Chlorine
    1. Incinerators
    2. Cement Kilns
    3. Lightweight Aggregate Kilns
    4. Liquid Fuel Boilers
    5. Solid Fuel Boilers
    6. Hydrochloric Acid Production Furnaces
    D. Standards for Dioxins/Furans
    1. Incinerators
    2. Cement Kilns
    3. Lightweight Aggregate Kilns
    4. Liquid Fuel Boilers
    E. Non-Dioxin Organic HAP
    F. Mercury
    1. Incinerators
    2. Cement Kilns
    3. Lightweight Aggregate Kilns
    4. Liquid Fuel Boilers
    5. Solid Fuel Boilers
    G. Normalization
    H. Potential Implications to the Compliance Date Provisions If 
Standards Are Remanded to EPA

I. Background

    The Hazardous Waste Combustor (HWC) Maximum Achievable Control 
Technology (MACT) rule, 70 FR 59402 (October 12, 2005), adopts separate 
standards for six source categories, the common link being that sources 
in each category burn hazardous waste. These sources are incinerators, 
cement kilns, lightweight aggregate kilns, solid fuel boilers, liquid 
fuel boilers, and hydrochloric acid production furnaces. Liquid fuel 
boilers are further subcategorized into those burning higher heating 
value hazardous wastes and lower heating value hazardous wastes. The 
following hazardous air pollutants (``HAP'') are regulated for each of 
these source categories: dioxins and furans (``D/F''); semivolatile 
metals (lead and cadmium) (``SVM''); low volatile metals (arsenic, 
beryllium and chromium) (``LVM''); mercury, particulate matter (``PM'') 
(as a surrogate for the remaining HAP metals (antimony, cobalt, 
manganese, nickel, and selenium), and also to control HAP metals in all 
inputs to the units which are not hazardous waste); hydrogen chloride/
chlorine (measured as total chlorine) (``TCl''); carbon monoxide/total 
hydrocarbons (``CO/HC'') (as surrogates for non-dioxin organic HAP (and 
in a few cases, dioxin as well); and destruction removal efficiency 
(``DRE'') (an aspect of control of non-dioxin organic HAP, and in a few 
cases, dioxin).
    On March 13, 2007, the United States Court of Appeals for the 
District of Columbia Circuit (D.C. Circuit) issued its decision in 
Sierra Club v. EPA, 479 F.3d 875 (2007) (``Brick MACT''). EPA has 
reexamined the rule to determine if it is compliant with the statute 
with respect to the issues discussed in the Court's opinion, and 
specifically whether the MACT floors for each standard are compliant. 
For the most part, EPA believes that they are. The basic reason, for 
those standards EPA plans to retain, is that the rule identifies as 
best performers--the best performing 12 per cent or best performing 
five sources in smaller source categories for existing sources, and the 
best controlled single source for new sources--those sources which are 
likely to emit the least HAP over time, and reasonably estimates these 
sources' level of performance. Put another way, the rule identifies as 
best performers those emitting the least HAP considering variability 
(i.e., their performance over time), and accounts for that variability 
as much as possible in estimating these sources' level of performance. 
See 70 FR at 59346 (``best performers are those that perform best over 
time (i.e., day-in, day-out)'').
    The statute does not address the question of whether, in assessing 
which sources perform best or are best controlled, emission levels 
should be evaluated over time, or in a single test result. Nor does 
Brick MACT, which states at 479 F.3d 880 that ``section [112(d)(3)] 
requires floors based on the emission level actually achieved by the 
best performers (those with the lowest emission levels)'', but does not 
refer to a time period for measurement. The following example shows why 
it is reasonable to determine which sources are the best performers by 
accounting in the first instance for what their emissions are over 
time. Assume that source A in a single test emitted 10 units of 
cadmium, and source B emitted 15 units. However, assume further that 
over time source A emits cadmium at a rate of 40 units and source B 
emits cadmium at a rate of 25 (the difference being that source B's 
performance is less variable). It is at the very least reasonable to 
view source B as the better performer; over time it emits less cadmium 
than source A. Indeed, given that the chief health risks of most HAP 
emitted by Hazardous Waste Combustors results from chronic rather than 
acute exposure (i.e., amount of repeated exposure over time as opposed 
to single exposure incidents), floor standards based on evaluation of 
sources' performance over time (i.e., standards which account for 
sources' variability) best address the sources' ultimate impacts on 
human health. See 70 FR at 59533-35 where EPA discusses human health 
benefits of the standards considering reductions in chronic exposure to 
HAP.

II. Consideration of Variability in Establishing MACT Floors

    EPA may consider variability in identifying best performers and 
their level of performance. See 70 FR at 59436. See also Brick MACT, 
479 F.3d at 881-82 (variability of best performing sources may be taken 
into account in establishing MACT floors).
    EPA in this rule identified two types of variability, run-to-run 
variability and test-to-test variability. Run-to-run variability 
``encompasses variability in individual runs comprising the compliance 
tests, and includes uncertainties in correlation of monitoring 
parameters and emissions, and imprecision of stack test methods and 
laboratory analyses.'' 70 FR at 59437. A shorthand description is that 
this is within-test variability. EPA quantified run-to-run variability 
using the statistical methodology set forth in Technical Support 
Document (``TSD'') Vol. III section 7.2; \2\ see also 70 FR at 59437/1-
2, 59438, and 59439 explaining the reasonableness of this statistical 
approach. The chief element of this quantification is simply the 
standard deviation in the performance test data (standard deviation 
being the usual statistical measure for assessing variation within a 
data set by comparing a single result with the average of the data 
comprising the data set). The result is an estimate of the value which 
the source would achieve in 99 of 100 future tests if it replicated the 
operating conditions of the compliance test. 70 FR at 59437; \3\ see 
also 69 FR at 21232 and n. 69 (April 20, 2004).
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    \2\ USEPA, ``Technical Support Document for HWC MACT Standards, 
Volume III: Selection of MACT Standards,'' (TSD Vol. III) September 
2005. Unless otherwise specified, all TSD references in this notice 
are to this document, which is available in the docket to the rule. 
See docket items EPA-HQ-OAR-2004-0022-0453, 0457, 0459, and 0460.
    \3\ More precisely, this is a modified prediction limit that 
ensures at the 95% confidence level that the average of the best 
performing sources could achieve the emission level in 99 or 100 
future test conditions based on a three-run average, assuming the 
best performers could initially replicate the compliance test 
conditions. TSD Vol. III at 7-7; 70 FR at 59437.

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[[Page 54878]]

    Existence of run-to-run variability is confirmed most evidently by 
the wide variations within different runs of the best performers' 
performance tests. Moreover, simply averaging these different run 
results would lead to standards which not even the best of the best 
performers would achieve over time. TSD Vol. III section 16.4. 
Comparative test results of best performing sources (i.e., tests of the 
same source at a different time) strongly suggest that run-to-run 
variability can be appreciable (although not the only measure of 
variability), since these sources have been shown consistently to emit 
more than the averaged emissions from the performance test identifying 
the source as best performing. See TSD Vol. III Tables 16-4, 16-5, 17-
1, 17-3. Failure to consider run-to-run variability could seriously 
underestimate a source's emissions over time. See TSD Vol. III section 
17.3.3, showing that even the lowest emitting Straight Emission sources 
could have emissions higher than floor levels under a methodology that 
considers run-to-run variability. EPA has comparative data from a 
number of lowest emitting incinerators for PM in single test results. 
In other tests, these same sources were typically unable to achieve the 
same level of performance, sometimes emitting up to seven times more 
PM. 69 FR at 21232 and n. 69 (April 20, 2004).
    Test-to-test variability results from variability in pollution 
device control efficiencies over time (depending on multitudinous 
factors, including for fabric filters the point in the maintenance 
cycle at which the source is tested, and for electrostatic 
precipitators variations in combustion gas moisture and particle 
resistivity), as well as measurement variability resulting from 
different sampling crews under different meteorological conditions and 
different analytical laboratories. Id. and n. 63. A shorthand 
description is that this is long-term variability. EPA demonstrated 
generally that: (a) Test-to-test variability exists; (b) it is not 
encompassed in EPA's statistical quantification of run-to-run 
variability; (c) the amount of test-to-test variability can be 
significant such that failing to account for it in some manner means 
that the sources' performance over time can be seriously underestimated 
(i.e., since their long-term variability would be ignored); and (d) 
sources which are lowest emitting in single emission tests may not be 
the lowest emitters over time due to their test-to-test variability. 70 
FR at 59437-438 and TSD Vol. III chapters 16 and 17; see also 70 FR at 
59439 explaining why total variability is not accounted for by 
compliance test conditions.
    EPA was able to provide a quantitative estimate of test-to-test 
variability in only one instance--where fabric filters are used to 
capture particulate matter. See discussion of PM standards in section 
III.A. below. In other instances, EPA accounted for test-to-test (i.e., 
long-term) variability in one of two ways: (a) Selecting as best 
performers those which minimized their long-term (i.e., test-to-test) 
variability by best controlling the aspects of performance (notably 
removal efficiency evaluated systemwide and hazardous waste HAP 
feedrate) within their control, or (b) using a surrogate for the HAP 
where EPA could assess the long-term variability associated with 
emissions of that surrogate, but could not otherwise assess long-term 
variability.
    EPA also carefully assessed a floor methodology which simply 
assumed that the lowest emitters in individual performance tests were 
the best performers. The major problem with such a methodology is that 
it ignores the sources' performance over time, leading to situations 
where the sources' level of performance may be assessed improperly. See 
TSD Vol. III chapters 16 and 17; 70 FR at 59442-446 (explaining why 
lowest emitters in individual performance tests \4\ are not always the 
best performers). EPA consequently used this methodology to identify 
best performers and their level of performance when it was not possible 
to assess sources' waste feedrate and systemwide removal efficiency.
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    \4\ The heading to this preamble section should have explicitly 
included the words ``in individual performance tests'' in the 
section title.
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III. Discussion of Individual Standards

A. Standards for Particulate Matter

1. Standards for Incinerator, Cement Kilns, Lightweight Aggregate 
Kilns, and Solid Fuel Boilers
    EPA adopted standards for particulate matter (``PM'') for all of 
the hazardous waste combuster source categories except for hydrochloric 
acid production furnaces.\5\ Particulate Matter is a surrogate for the 
HAP metals antimony, cobalt, manganese, nickel, and selenium, the HAP 
metals not covered by the standards for semi-volatile and low-volatile 
HAP metals (referred to as `nonenumerated metals' in this rulemaking). 
See section III.B. below. In addition, as explained in section III.B., 
the PM standard also controls all non-mercury HAP metals (i.e., semi-
volatile, low volatility, and nonenumerated HAP metals) in all 
nonhazardous waste inputs to HWCs. 70 FR at 59459. Since the PM 
standards are measured by total end-of-stack output, these standards 
account for all HAP metal input to hazardous waste combustion devices 
(other than mercury). Id.
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    \5\ The alternative metal standards, in lieu of PM standards, 
for incinerators, and liquid and solid fuel boilers are discussed in 
section III.B discussing standards using the SRE Feed floor 
methodology.
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    EPA used the Air Pollution Control Device methodology to establish 
floors for PM. Under this methodology, EPA determined as a matter of 
engineering judgment which devices best control PM emissions, ranked 
these means of control, and selected as the best performers those with 
the lowest PM emissions using the best control device. See TSD Vol. III 
section 7.4; see also id. at 16-2 ranking PM control devices from best 
to worst for each source category. The floor for each source category 
was then established based on the average of these lowest emitting 
sources' PM emissions (or the lowest emitter of these sources for the 
new source floor).
    In most instances, the lowest emitters in the performance test used 
for determining best performers were equipped with the best control 
device--some type of fabric filter (``FF''). Occasionally, a lower PM 
emitter in a single test was equipped with some other type of control 
device, or, in the case of three incinerators, no control device, but 
EPA ranked these sources as lower (i.e., worse) performing than FF-
equipped sources. EPA reevaluated carefully whether the lower ranking 
of these sources, in some instances resulting in their omission from 
the pool of best performers, is consistent with the holding of Brick 
MACT, 479 F.3d at 882-83, as well as Cement Kiln Recycling Coalition v. 
EPA, 255 F.3d 855, 863-65 (D.C. Cir. 2001), that floors are not to be 
set only on performance of sources equipped with certain technology 
unless that is the only factor affecting emissions, and that EPA must 
consider all means of control when selecting best performers.
    EPA of course accepts these holdings, and believes its approach 
here is consistent with the statute and applicable case law. EPA 
selected as best performers (or as the best controlled source) those 
sources it estimated to have the lowest PM emissions over time. EPA's 
selection process has a reasoned basis. Sources equipped with control 
devices other than FFs are likely to emit more over

[[Page 54879]]

time than they do in individual test conditions, even after adjusting 
test results to account for run-to-run variability. (Put another way, 
these sources' performance in individual test conditions are likely not 
representative of what they will emit over time.) This is because test-
to-test variability, that is, long-term variability, has not been taken 
into account. Since these other control devices are known to be more 
variable and less efficient than FFs, TSD Vol. III pp. 16-3 to 4 and 
11, failure to consider long-term variability (i.e., looking 
exclusively at results of single performance tests) results in these 
sources' performance not being fully characterized. Long-term 
variability exists due to, among other things, variation over time in 
control device performance and varying ash feed rates.\6\ EPA confirmed 
in a series of analyses of HWCs that this test-to-test variability for 
non-FF equipped devices both exists and is appreciable. See TSD Vol. 
III section 16.5 showing among other things that ostensibly lowest 
emitting, non-FF equipped sources in other tests (i.e., other occasions 
when the same source was tested) were unable to duplicate (i.e., 
achieve): (a) Their own level of performance (i.e., their performance 
in the other test), (b) their own performance adjusted to account for 
run-to-run variability, (c) floors based on the average of the lowest 
single test emitters' performance, (d) design level of the floor 
actually adopted in the rule (i.e., the level sources would design to 
in order to comply with the rule), and, in one case, (e) the floor 
level established in the rule (i.e., the floor reflecting application 
of the Air Pollution Control Device methodology). EPA further examined 
whether this difference in performance resulted from legitimate 
operating variability, rather than from differing ash feed rates, and 
in the instance where direct comparison was possible, determined that 
it did not. TSD Volume III pp. 16-15 through 17.
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    \6\ Ash content is an indicator of the noncombustible matter 
(i.e., inorganic content, including metals) in the feed to the 
source.
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    In contrast, EPA was able to quantify the long-term performance 
(i.e., performance accounting for both run-to-run and test-to-test 
variability) of HWC sources equipped with FFs. This is the only type of 
air pollution control device for HWCs, and the only pollutant, for 
which such a calculation is possible. The reason this quantification is 
possible is that FFs are less variable than other control devices, and 
perform relatively constantly regardless of input loadings. 70 FR at 
59449. EPA thus developed a so-called Universal Variability Factor 
algorithm for fabric filters, which is derived from the quantified 
measure of the total variability (i.e., both run-to-run and long-term 
test-to-test variability) of the FF-equipped hazardous waste combusters 
identified as best performers based on the historical test conditions 
for those sources. See TSD Vol. III section 5.3.
    As a result, for HWCs EPA has a considerably more reliable idea of 
what fabric filter-equipped sources' actual performance for PM is over 
time than for any other type of control device-equipped source (or for 
sources without air pollution control devices). Second, as just noted 
above, the record demonstrates that the performance data from sources 
that emitted less PM in individual performance tests but are not 
equipped with FFs significantly underestimates the amount of PM these 
sources emit over time (i.e., fails to account for their long-term 
variability). Third, over time, these emissions in some instances 
exceed (i.e., are higher than) the lowest emitting FF-equipped sources, 
even though emitting less in an individual performance test. 70 FR at 
59448; TSD Vol. III section 16.5. Putting all this together, EPA 
selected the lowest emitting FF-equipped sources as the best 
performing. 70 FR at 59448.
    This approach is consistent with the statute and applicable case 
law. EPA selected as best performers (or best controlled sources) those 
sources it reasonably estimated to have the lowest PM emissions over 
time. Performance of units equipped with fabric filters can be reliably 
estimated over time--i.e., all of the variability can be quantified. 
Performance of other units over time cannot be estimated as reliably 
(the long-term variability cannot be quantified at all), but is known 
to be less efficient and more variable. Short-term performance tests 
thus demonstrably and dramatically understate the amount of PM (and HAP 
metal) these sources emit, so that these units could (and demonstrably 
do in some instances) emit more PM (and therefore more HAP metal) than 
the lowest emitting FF-equipped sources notwithstanding lower PM 
emissions in individual tests. The D.C. Circuit has held repeatedly 
that EPA may use reasonable means to estimate the performance of best 
performing sources, and may account for sources' variability in doing 
so. CKRC, 255 F.3d at 865-66; Mossville, 370 F.3d at 1240, 1242; 
National Lime Ass'n v. EPA, 627 F. 2d 416, 431 n. 46, 443 (D.C. Cir. 
1980); see also Brick MACT, 479 F.3d at 881-82 (estimates of 
variability are to be for the variability of the best performing 
sources). EPA's approach here is consistent with these requirements.
    The D.C. Circuit has stressed in both Brick MACT and CKRC that 
factors such as low HAP feed that influence emissions cannot be ignored 
in assessing performance. 479 F.3d at 882-83; 255 F.3d at 864-65. EPA 
thus carefully reexamined those instances where low PM emitters in 
single tests were not equipped with any pollution control equipment so 
that their emission levels necessarily reflected low ash inputs. There 
are three incinerators that had lower PM emissions in single tests that 
were lower than the worst of the lowest-emitting FF-equipped 
incinerators on whose performance the floor standard is based. TSD Vol. 
III App. F at APCD-INC-PM. EPA continues to believe that it properly 
chose not to include these sources among the pool of best performers. 
First, even in single test conditions, these sources' emissions were 
not significantly lower (0.0018 to 0.0009 gr/dscf lower, that is, 
roughly a 7-14% difference) than the average of the best performing 12% 
of sources EPA identified as best performing using the Air Pollution 
Control methodology. Id. These sources also emit more PM than all but 
one of the best performing incinerators in EPA's pool of best 
performers, and the difference in performance between these 
uncontrolled sources and the last of the EPA pool is small, roughly a 
factor of 2. Id. Since these devices lack any pollution control 
equipment, their performance over time will be highly variable as ash 
feedrates vary and their emissions could \7\ well exceed the emissions 
of the sources comprising EPA's pool of best performing incinerators. 
Second, and of at least equal importance, low ash feedrates are not a 
guarantee of low HAP metal emissions. Low PM emissions from 
uncontrolled sources could still reflect high metal HAP emissions 
since, if the ash has high metal content, all of it would be emitted. 
See 70 FR at 59449 (``ash feedrates are not reliable indicators of 
nonmercury metal HAP feed control levels and are therefore 
inappropriate parameters to assess in the MACT evaluation process. For 
example, a source could reduce its ash feed input by reducing the 
amount of silica in its feedstreams. This would not result in * * * 
emission reductions of metal HAP''). In contrast, ``particulate matter 
emissions from baghouses [e.g., FF-equipped units] are not 
significantly affected by inlet particulate matter

[[Page 54880]]

loadings'', id., so that PM (and hence HAP metal emissions) from these 
units will remain best controlled regardless of relative amounts fed to 
the device. See also TSD Vol. III section 17.7 documenting that PM 
emissions from FF-equipped sources are not affected appreciably by 
inlet loadings. EPA is thus giving preference as best performers to 
those incinerators we know are effectively controlling non-mercury 
metal HAP because they are the lowest emitting of the most efficiently 
controlled sources. Moreover, although a severable part of the 
rationale, EPA believes it reasonable that most efficiently controlled 
sources can be viewed as ``best performing'' and ``best controlled'' 
under appropriate circumstances. See discussion in section B.1 below.
---------------------------------------------------------------------------

    \7\ There are no comparative test data in the record for these 
sources.
---------------------------------------------------------------------------

    EPA does, however, believe that certain parts of the justification 
for the PM standards in the final rule are not proper after Brick MACT, 
and EPA is no longer relying on them and will revise the record 
accordingly. The principal revisions are to discussions relating to how 
EPA considered raw material inputs in assessing which sources are best 
performers. See Brick MACT, 479 F. 3d at 882-83. The specific 
alterations EPA is contemplating (generally excising existing language) 
are found in red line/strike out versions of the Preamble, Technical 
Support Documents, and Response to Comment Document which EPA has 
placed in the docket for this rule.
2. Standards for Liquid Fuel Boilers
    EPA's initial decision is not to defend the PM standard for liquid 
fuel boilers (LFBs), and we thus contemplate requesting the Court to 
remand the standard so that EPA can reexamine it. Most of the liquid 
fuel boilers with lowest PM emissions are uncontrolled units with 
extremely low ash feeds. TSD Vol. III App. F at APCD-LFB-PM. Unlike the 
situation with incinerators, the difference in PM emissions between 
these sources and those lowest-emitting LFBs equipped with FFs is 
great, ranging from a factor of 6 (comparing lowest emitting FF-
equipped LFB with lowest emitting uncontrolled LFB) to over three 
orders magnitude (comparing worst of the lowest emitting FF-equipped 
LFB to lowest emitting uncontrolled LFB). Id. These uncontrolled 
sources' emissions are also roughly an order of magnitude lower than 
the promulgated floor based on performance of FF-equipped sources. Id. 
There are also ten uncontrolled LFBs in the data base with lower PM 
emissions than the lowest emitting FF-equipped LFB. Id. Under these 
circumstances, EPA is less certain that these LFBs could emit more PM 
over time than the FF-equipped sources EPA selected as best performers 
and therefore will reexamine the standard with a view to amending it. 
However, EPA notes further that this difference in emission levels 
between controlled and uncontrolled sources suggests that 
subcategorization may be appropriate. EPA intends to investigate that 
possibility in subsequent rulemaking.

B. Standards for Semivolatile Metals and Low Volatility Metals

1. Methodology To Establish Floor Levels
    EPA used the so-called system removal efficiency/hazardous waste 
feed control (``SRE Feed'') methodology to establish floor levels for 
semivolatile metal HAP (``SVM''--lead and cadmium) and low volatile 
metal HAP (``LVM''--arsenic, beryllium, and chromium) for all source 
categories except hydrochloric acid production furnaces. Under this 
methodology, best performers are ranked by hazardous waste feed rate of 
metal HAP, and by system removal efficiency (the degree to which HAP 
are removed from stack emissions across the entire system, be it by an 
air pollution control device or by any other means). 70 FR at 59441. 
Best performers are those with the best combination of hazardous waste 
feed rate for the HAP at issue and system removal efficiency (i.e., 
lowest hazardous waste feed rate and best removal efficiency). EPA 
assessed SVM and LVM separately, so that there are separate pools of 
best performing sources for each of these HAP metal groups for each of 
the source categories.
    Once best sources are identified by this methodology, EPA 
calculated the floor (accounting for run-to-run variability) based on 
the averaged emission levels of SVM or LVM from these best performing 
sources (or for new sources, the SVM or LVM emission level of the 
single best performer). For source categories where SVM and LVM 
standards are normalized by hazardous waste heat input (cement kilns, 
lightweight aggregate kilns, and the higher heating value hazardous 
wastes subcategory for liquid fuel boiler), see 70 FR at 59451-53, the 
standard is expressed exclusively in terms of SVM or LVM attributable 
to hazardous waste inputs. For all source categories, total SVM and LVM 
emissions are addressed and controlled by the PM standard.
    The SRE Feed methodology does not always identify the lowest 
emitters of SVM or LVM in single tests as the best performers; it 
identifies the lowest emitters as the sources with the best combination 
of hazardous feed rate control and back end control (removal efficiency 
across the entire system). Some of these sources were also the lowest 
emitters in single test results, but were not in all cases. EPA 
selected this methodology, rather than the so-called Straight Emissions 
approach of simply identifying best performers as those with the lowest 
emissions after accounting for run-to-run variability, because the SRE 
Feed methodology better identifies who the lowest emitters will be over 
time, and better assesses their performance (i.e., how much SVM or LVM 
they will emit as they operate). 70 FR at 59441-442; TSD Vol. III at 
17-1. SRE Feed best performers are likely to emit less of these metals 
over time than sources identified as best under the Straight Emissions 
methodology--averaged performance of lowest emitting sources in the 
most recent performance test accounting for run-to-run variability (see 
TSD Vol. III at section 7.2)--because the Straight Emissions 
methodology (even after accounting for run-to-run variability) ignores 
sources' long-term (test-to-test) variability, and so underestimates 
(indeed, ignores) their performance over time. The SRE Feed methodology 
accounts for test-to-test variability, albeit qualitatively. Id.\8\ For 
the same reason, the SRE Feed methodology better estimates sources' 
performance over time since it accounts in some measure for their long-
term variability instead of ignoring it. As discussed earlier, elements 
of long-term variability include such things as chlorine feed rates 
(since metals are more volatile in the chlorinated form), back-end 
control devices' controllable operating parameters (e.g. ESP power 
levels, pressure drop across baghouses, and other such operating 
parameters), the matrix in which the metal is fed (solid, liquid, 
pumpable) and the hazardous waste feedrate. TSD Vol. III at p. 17-5. 
SRE Feed best performers are those that best control these and other 
controllable parameters and therefore are less variable (i.e., are more 
efficient at controlling SVM and LVM emissions), and therefore likely 
to emit less SVM and LVM over time. Id. at p. 17-11. Put more broadly, 
the methodology best evaluates the two things sources can do to control 
SVM and LVM emissions: limit the feed rate of these HAP in hazardous 
waste (since hazardous waste feed rate is controlled under RCRA rules), 
and manage

[[Page 54881]]

controllable parameters to limit emissions across the entire system 
(both through emission control device control and by any other means), 
the result being that these sources are likely to emit less SVM and LVM 
over time. 70 FR at 59441.
---------------------------------------------------------------------------

    \8\ See TSD Vol. III at 17-1 to 4 explaining why long-term 
variability for SVM and LVM cannot be determined quantitatively, 
even for sources equipped with baghouses (FFs).
---------------------------------------------------------------------------

    Data confirm that lowest emitters in single tests (i.e., performers 
identified as best under the Straight Emissions methodology) can and do 
emit more SVM and LVM over time than the sources EPA identified as best 
performers using the SRE Feed methodology. See TSD Vol. III sections 
17.2 and 17.3.1 and 17.3.2. Looking at all the data in the record where 
there were multiple test results (i.e., tests conducted at different 
times) from sources with the lowest SVM or LVM emissions in single 
tests, EPA found that a) three of four of these sources emitted more 
SVM or LVM in historical tests than allowed under the Straight 
Emissions floor (i.e., average emissions (not considering run-to-run 
variability) of SVM or LVM were higher than the average of the best 
performers using the Straight Emissions methodology (which considers 
run-to-run variability)) (id. Table 17-1); \9\ (b) 5 of 15 of these 
sources were projected to emit more SVM or LVM than allowed under the 
SRE Feed floor using the reasonable assumption that these sources fed 
the same amount of LVM and SVM in hazardous waste as they did in the 
performance test identifying them as a best performer (lowest emitter) 
under the straight emission approach, but had the system removal 
efficiency demonstrated in their other tests. Id. at Tables 17-2 and 
17-3; \10\ and (c) 8 of 13 straight emission best performers would 
exceed the SRE Feed floor if their system removal efficiency from all 
tests (i.e., whether the system removal efficiency was higher or lower 
than that demonstrated in the single performance test identifying it as 
a best performer under the straight emissions methodology) were pooled 
and applied to the hazardous waste federate for LVM or SVM used in the 
single performance test identifying it as a best performer under the 
straight emissions methodology. Id. at 17.3.2 and Tables 17-6 and 7. In 
addition, most of the straight emissions best performers emitted more 
SVM and LVM in previous performance tests than they did in the single 
performance test identifying them as a straight emission best performer 
(or were projected to do so under the same reasonable assumptions), and 
often exceeded their earlier performance by wide margins (failing 
routinely, for example, to achieve their own performance test results 
adjusted upward to account for run-to-run variability, the Straight 
Emissions approach floor level (which also accounts for run-to-run 
variability), and the design level of the SRE Feed floor level). See 
TSD Vol. III sections 17.2 and 17.3.1 and 17.3.2.
---------------------------------------------------------------------------

    \9\ It should be noted that source 3016 was feeding more LVM in 
this test than in its most recent performance test, although the 
source was operating within its permit limits, and so far as can be 
determined was also otherwise properly designed and operated in this 
test.
    \10\ EPA also showed that these sources were operating properly 
in the tests where they removed SVM and LVM less efficiently. TSD 
Vol. III at 17-14 to 15 and Tables 17-4 and 5.
---------------------------------------------------------------------------

    EPA's approach is consistent with the statute and with applicable 
caselaw. EPA may consider variability in assessing sources' 
performance, and it did so here for the evident reason that variability 
is an aspect of a source's performance. CKRC, 255 F.3d at 865-66; 
Mossville, 370 F.3d at 1242. Here, short-term and long-term variability 
(i.e., run-to-run and test-to-test) in SVM and LVM performance 
demonstrably exists. The SRE Feed methodology accounts for both types 
of variability. The Straight Emissions methodology demonstrably does 
not. The Straight Emissions methodology thus not only consistently 
underestimates sources' performance, but identifies as best performers 
those which may emit more SVM and LVM over time. For these reasons we 
believe the record of this rulemaking demonstrates that the SRE Feed 
methodology better accounts for variability, and hence performance, 
than does the Straight Emissions approach (even with consideration of 
run-to-run variability), and consequently, the SRE Feed methodology 
more accurately identifies the best performing sources and their level 
of performance.
    It is also no answer to say that the Straight Emissions best 
performing sources could simply retrofit their devices to achieve over 
time what they were able to achieve in a single performance test. 
Section 112(d)(3) requires EPA to determine the best performers and 
their level of performance based on sources as they now exist, not how 
they might be retrofitted. Requiring even the pool of best performers 
(i.e., those whose performance was measured at below the average of the 
best performers) to retrofit to meet a floor level is a de facto beyond 
the floor standard and therefore impermissible unless costs and other 
factors under section (d)(2) factors are considered. 70 FR at 59445. 
Moreover, a source so retrofitted would not be an existing source as 
required by section 112(d)(3), but rather some hypothetical entity 
which does not even presently exist. See 71 FR 14665 (March 23, 2006).
    As noted above, the SVM and LVM standards which are normalized by 
hazardous waste thermal input apply only to SVM and LVM contributed by 
the hazardous waste. MACT standards must address all HAP emitted by a 
source, not just some portion of the HAP. Brick MACT, 479 F.3d at 882-
83 (raw material input contributions to HAP emissions must be addressed 
by MACT floor). Although most SVM and LVM emitted by these sources 
comes from the hazardous waste,\11\ hazardous waste is not the sole 
input of these metals. However, all SVM and LVM emissions from these 
sources is controlled by virtue of the PM standard. In addition, 
although the SVM and LVM floor standards for cement kilns and 
lightweight aggregate kilns are normalized by hazardous waste thermal 
input, EPA also capped these standards by the interim standards for SVM 
and LVM, which are standards that control all SVM and LVM emissions 
emitted from the combustor, not just emissions of SVM and LVM from 
hazardous waste.\12\ Moreover, there is strong direct correlation 
between the control of total PM and control of metal HAP (including SVM 
and LVM), so that emission limits reflecting best PM control will also 
similarly control the total SVM and LVM. Sierra Club v. EPA (``Primary 
Copper MACT''), 353 F.3d 976, 984-85 (D.C. Cir. 2004) (PM proper 
surrogate for HAP metals ``even in light of the potential variability 
of impurities in copper ore''). Furthermore, as a cross-check, EPA 
determined that total SVM and LVM emissions from the sources EPA 
identified as the PM best performers from these source categories are 
generally comparable to (and often lower than) total SVM and LVM 
emissions from the sources identified as best performers under EPA's 
SRE Feed methodology.\13\ Thus, on the facts here, the thermally 
normalized floors for SVM and LVM (i.e., the SVM and LVM standards for 
cement kilns, lightweight aggregate kilns, and the higher heating value 
hazardous wastes subcategory of liquid fuel boilers), in combination 
with the PM standards, provide control of

[[Page 54882]]

SVM and LVM reflecting the average SVM and LVM emissions of the best 
performing sources.
---------------------------------------------------------------------------

    \11\ See Source Data for Hazardous Waste Combustors, Source 
Category Summary Sheets, at http://www.epa.gov/epaoswer/hazwaste/combust/finalmact/source.htm.
    \12\ See 70 FR at 59457-458, Sec.  63.1220(a)(3)(ii), 
(a)(4)(ii), (b)(3)(ii), and (b)(4)(ii), and Sec.  63.1221(a)(3)(ii), 
(a)(4)(ii), (b)(3)(ii), and (b)(4)(ii).
    \13\ See note from Bob Holloway, USEPA, to Docket ID No. EPA-HQ-
OAR-2004-0022 entitled ``SVM/LVM Emissions from PM Best Performers 
Are Generally Comparable to SVM/LVM Emissions from SVM/LVM Best 
Performers,'' dated August 23, 2007.
---------------------------------------------------------------------------

    EPA further justified its use of the SRE Feed methodology on two 
additional bases, both of which are severable from the analysis just 
presented. First, EPA appropriately utilized the SRE Feed methodology 
because the Straight Emissions approach would force some best-
controlled commercial hazardous waste treatment units to stop burning 
hazardous waste (or to burn less waste), even though hazardous waste 
must be treated before it can be land disposed under sections 3004(d), 
(e), (g), and (m) of RCRA and combustion is the only means of 
successfully treating the hazardous waste. 70 FR at 59442; TSD Vol. III 
section 17.4. EPA noted further that the Clean Air Act requires that 
EPA take into account RCRA requirements when issuing MACT standards for 
hazardous waste combustion units.\14\ CAA section 112(n)(7). Although a 
severable part of EPA's rationale, 70 FR at 59447/3, EPA continues to 
believe that use of the Straight Emissions methodology is unreasonable 
here because it could have significant adverse cross-media 
environmental impacts by reducing the amount of needed, and statutorily 
mandated hazardous waste treatment capacity. See id. at 59442 (``EPA 
doubts that a standard which precludes effective treatment mandated by 
a sister environmental statute must be viewed as a type of best 
performance under section 112(d)''). EPA's concern here is not that 
certain sources are unable to achieve a floor standard. See Brick MACT, 
479 F.3d at 881-82. Rather, the concern is the adverse cross-media 
environmental impact resulting from undermining ``the heart of RCRA's 
hazardous waste management program'', the restrictions on land disposal 
of untreated hazardous waste. Chemical Waste Management v. EPA, 976 
F.2d 2, 23 (D.C. Cir. 1992). Section 112(n)(7) of the Clean Air Act 
requires EPA to consider RCRA standards when adopting section 112(d) 
standards for RCRA sources, and EPA's consideration of the issue here 
reinforces the conclusion that the SRE Feed methodology is reasonable, 
and the proper means here of assessing which sources are best, and 
their level of performance, for SVM and LVM emissions.
---------------------------------------------------------------------------

    \14\ EPA investigated the possibility of subcategorizing by 
commercial/non-commercial sources but found this undesirable because 
it would lead to anomalously high floors for some subcategories due 
to sparse available data. 70 FR at 59442 and n. 78.
---------------------------------------------------------------------------

    Second, as a legal matter, section 112(d)(3) does not specifically 
address the question of whether ``best performing'' sources are those 
with the lowest net emissions, or those which control HAP emissions the 
most efficiently. 70 FR at 59443. EPA posited the example of whether a 
source emitting 100 units of HAP and feeding 100 units of the HAP must 
be considered better performing than a source emitting 101 units of the 
HAP but feeding 10,000 units. Id. Indeed, floors for new sources are to 
be based on the performance of the ``best controlled'' similar source. 
Section 112(d)(3). In the example just given, a source with control 
efficiency of 99.9 per cent can naturally be viewed as better 
controlled than one with 0 per cent control efficiency. EPA's decision 
to incorporate control efficiency (i.e., system removal efficiency) 
into the SRE Feed methodology as one of the two factors used to 
identify best performing/best controlled sources reasonably reflects 
that the statute allows performance to be evaluated in terms of control 
efficiency. See further discussion of this issue in the analysis of the 
total chlorine emission standard for hydrochloric acid production 
furnaces.
    EPA does, however, realize that certain parts of the justification 
for the SVM and LVM standards in the final rule may not be consistent 
with Brick MACT, and EPA is no longer relying on them. These relate 
principally to how MACT standards reflect HAP metal inputs from 
variable raw materials. The specific alterations EPA is contemplating 
(generally excising existing language) are found in red line/strike out 
versions of the Preamble, Technical Support Documents, and Response to 
Comment Document which EPA has placed in the docket for this rule.
2. Alternatives to the Particulate Matter Standard for Incinerators, 
Liquid Fuel Boilers, and Solid Fuel Boilers
    EPA promulgated alternatives to the PM standard for incinerators, 
liquid fuel boilers, and solid fuel boilers.\15\ In the case of liquid 
fuel boilers, separate alternatives to the PM standard were finalized 
for each subcategory: those burning higher heating value hazardous 
wastes and those burning lower heating value hazardous wastes. The 
alternative to the PM standard allows sources to comply with standards 
limiting emissions of all SVM and LVM metals, including the five 
nonenumerated metal HAP not covered by the standards for SVM and LVM, 
in lieu of complying with the PM standard. Under these alternatives, 
the numerical emission limits for SVM and LVM HAP are identical to the 
promulgated standards. However, for SVM, the alternative standard 
applies not only to the combined emissions of lead and cadmium, but 
also includes selenium, a semivolatile nonenumerated metal HAP; for 
LVM, the standard applies to the combined emissions of arsenic, 
beryllium, chromium, antimony, cobalt, manganese, and nickel, the 
latter four being low volatile nonenumerated metal HAP.
---------------------------------------------------------------------------

    \15\ For incinerators, the alternative to the PM standard are 
promulgated Sec. Sec.  63.1206(b)(14) and 63.1219(e). For the higher 
and lower heating value hazardous wastes subcategories for the 
liquid fuel boiler category, the alternatives are promulgated under 
Sec.  63.1217(e)(2) and (e)(3). The alternative to the PM standard 
is under Sec.  63.1216(e) for solid fuel boilers.
---------------------------------------------------------------------------

    As noted above, some SVM and LVM standards are normalized by 
hazardous waste thermal input and apply only to SVM and LVM contributed 
by the hazardous waste. For these standards, SVM and LVM emissions from 
nonhazardous waste inputs is controlled by the PM standard. However, if 
a source were to elect to comply with the alternative to the PM 
standard, then the nonhazardous waste inputs would not be controlled 
because, under the alternative, the source would not be required to 
comply with a PM standard. In such instances, the alternative to the PM 
standard would not address all HAP emitted by a source. This does not 
appear to be consistent with the holding of Brick MACT that the 
standard must apply to all HAP emitted. 479 F.3d at 882-83. Of the 
source categories for which EPA promulgated alternatives to the PM 
standard, the higher heating value hazardous wastes subcategory for 
liquid fuel boilers is the only category for which SVM and LVM 
standards normalized by hazardous waste thermal input were established. 
Therefore, EPA believes (subject to comment) that it must reassess the 
alternative to the PM standard for this subcategory (and intends to 
seek remand of this standard). See Sec.  63.1217(e)(2)(ii) and 
(e)(3)(ii).
3. Alternative Mercury, Semivolatile Metals, Low Volatile Metals, and 
Total Chlorine Standards for Cement Kilns and Lightweight Aggregate 
Kilns
    EPA promulgated provisions that allow cement kilns and lightweight 
aggregate kilns to petition the Administrator for alternative mercury, 
semivolatile metals, low volatile metals,

[[Page 54883]]

and total chlorine standards.\16\ 64 FR at 52962-967 and 70 FR at 
59503-504. Under these provisions, the alternative standard was not 
prescribed, and could take the form of an operating requirement, such 
as a hazardous waste feedrate limitation of metals and chlorine or an 
emission limitation, subject to approval by the Administrator. The rule 
discusses two sets of circumstances under which a source could petition 
for such an alternative standard. One reason is that the source cannot 
achieve the standard due to contributions of metals and chlorine HAP in 
the raw materials. The second reason is limited to mercury, and applies 
in situations where a source cannot comply with the mercury standard 
when mercury is not present in the raw materials at detectable levels 
(e.g., the mercury emission standard could be exceeded by a source if 
it assumed mercury is present in the raw materials at the detection 
limit). These circumstances appear to be inappropriate bases for an 
alternative standard after Brick MACT. Accordingly, EPA currently 
intends to seek a remand of these alternative metals and total chlorine 
standards and remove these provisions in a subsequent rulemaking.
---------------------------------------------------------------------------

    \16\ The alternative standard provisions are promulgated under 
Sec.  63.1206(b)(9) for lightweight aggregate kilns and Sec.  
63.1206(b)(10) for cement kilns.
---------------------------------------------------------------------------

4. Alternative Mercury Standards for Cement Kilns and Lightweight 
Aggregate Kilns Under the Interim Standards
    EPA promulgated an alternative to the interim standards for mercury 
for cement and lightweight aggregate kilns in 2002. Section 
63.1206(b)(15) and 67 FR 6792 (February 13, 2002). Under this 
alternative, sources are allowed to comply with a hazardous waste 
maximum theoretical emissions concentration of mercury.\17\ This 
alternative mercury standard does not address all mercury emitted by a 
source, and, therefore, is not permissible in light of the holding of 
Brick MACT that the standard must apply to all HAP emitted. 479 F.3d at 
882-83. Accordingly, EPA currently intends to seek a remand of these 
alternative standard provisions and remove them in a subsequent 
rulemaking.
---------------------------------------------------------------------------

    \17\ Maximum theoretical emissions concentration (MTEC) is a 
term to compare metals (and chlorine) feedrates across sources of 
different sizes. MTEC is defined as the metals (or chlorine) 
feedrate divided by the gas flow rate and is expressed in units of 
ug/dscm.
---------------------------------------------------------------------------

C. Standards for Total Chlorine

    EPA established standards for total chlorine (TCl, which controls 
emissions of both hydrochloric acid and chlorine) for all of the source 
categories. For all of the source categories except HCl production 
furnaces, EPA established floors using the SRE Feed methodology 
described in the previous section. For HCl production furnaces, EPA 
selected sources with the best removal efficiency as the best 
performers. EPA believes that most of these standards are consistent 
with the statute and applicable caselaw, although certain of the 
standards probably are not.
1. Incinerators
    For hazardous waste incinerators, all of the best performers using 
the SRE Feed methodology were also the lowest emitters using the 
Straight Emissions methodology. Thus, choice of floor methodology is 
not at issue here. However, EPA found that the analytic method used to 
gather these data is biased below 20 ppmv. 70 FR at 59427-428. EPA's 
determination of how to estimate these best performers' level of 
performance is explained in detail in 71 FR at 52628-30 (Sept. 6, 
2006). As there stated, this determination is consistent with Brick 
MACT and all other applicable statutory and caselaw.
2. Cement Kilns
    EPA used the SRE Feed methodology to establish floors for new and 
existing sources, but believed that the data did not fully reflect 
variability that best performing kilns experience due to fluctuating 
alkalinity levels within the kiln. Rather, the TCl emissions data 
reflect the alkalinity of the limestone raw material used at the time 
of performance tests. 70 FR at 59469-70, TSD Vol. III section 13.7.1. 
To account for this variability, EPA assumed a 90 per cent system 
removal efficiency for all cement kiln sources. The best performing 
sources then effectively become the lowest chlorine feeders. Although 
this assumed system removal efficiency has some factual basis, see 
Table 1 at 70 FR 59470 showing that the median of the best performing 
sources (Ash Grove) demonstrated removal efficiencies ranging from 85.1 
to 98.8%, the standard reflects concerns relating to raw material 
variability, and also may reflect a level that is achievable (albeit by 
best performers) rather than actually achieved. Neither of these 
rationales is permissible after Brick MACT, 479 F.3d at 880-81, 882-83. 
Accordingly, subject to consideration of comments on this issue, EPA 
currently intends to seek a remand on this standard and reexamine it in 
a subsequent rulemaking. EPA notes further that the health-based 
compliance alternatives for total chlorine under Sec.  63.1215 would 
not be affected by this reexamination and thus would provide an 
alternative means of demonstrating compliance.
3. Lightweight Aggregate Kilns
    Choice of a floor methodology for TCl is essentially academic for 
existing lightweight aggregate kilns, since both the SRE/Feed and 
Straight Thermal Emission (and Straight Mass Emission) methodologies 
yield floor levels higher than the interim standard for these devices, 
in which case the floor level is capped by the level of the interim 
standard. 70 FR at 59457; see TSD Vol. III appendices C, D, and E for 
data and calculations. The reason for this seeming anomaly in all the 
methodologies is that EPA has little data from this source category 
(and there are only a few sources to begin with), so that differences 
in individual performance runs are magnified when the standard is 
calculated. In addition, all of the data in the record came from tests 
conducted before EPA adopted the interim standards. This is especially 
relevant for this standard because the interim standard is a beyond-
the-floor standard. See generally TSD Vol. III chapter 19. The interim 
standard thus remains the best measure of evaluating best performing 
sources.
    However, for new sources, EPA noted only that the new source floor 
calculated using the SRE Feed methodology would be less stringent than 
the interim standard but did not closely examine whether the 
methodology clearly identified the best controlled source. TSD Vol. III 
section 12.6.3. EPA therefore intends to reexamine this standard in a 
subsequent rulemaking, subject to consideration of comment (and to seek 
remand of the standard).
4. Liquid Fuel Boilers
    a. Higher Heating Value Hazardous Wastes Subcategory. EPA believes 
(subject to comment) that it must reassess this standard (for both new 
and existing sources) since the standard applies only to TCl 
attributable to hazardous waste inputs, and currently intends to seek 
remand of the standard. See Sec.  63.1217(a)(6)(ii). This is not 
permissible in light of the holding of Brick MACT that the standard 
must apply to all HAP emitted, notwithstanding variable HAP levels in 
raw materials. 479 F.3d at 881-82.
    b. Lower Heating Value Hazardous Wastes Subcategory. The SRE Feed 
and Straight Emissions methodologies give

[[Page 54884]]

the same floor value for this subcategory, and the standard applies to 
all TCl emissions from the boiler, not just those attributable to 
hazardous waste. See Sec.  63.1217(a)(6)(i). The issue is how to 
account for analytical bias at levels below 20 ppmv, and EPA's 
resolution of the issue is explained at 71 FR at 52628-630. EPA does 
not believe this approach raises issues under the statue, or under 
Brick MACT or other applicable caselaw.
5. Solid Fuel Boilers
    The SRE Feed and Straight Emission methodologies give the same 
floor level for both existing and new solid fuel boilers, so the issue 
of appropriate floor methodology is academic. TSD Vol. III at App. E 
and C.
6. Hydrochloric Acid Production Furnaces
    The TCl standard for this source category controls TCl emissions 
and also serves as a surrogate for all metal HAP. TSD Vol. III sections 
15.2 and 15.3. EPA selected as best performers sources with the best 
TCl system removal efficiency (or, for new sources, the single source 
with the best TCl system removal efficiency). The standard is then 
expressed as a required degree of control: 99.923 percent for existing 
sources (the average efficiency of the five best controlled sources), 
99.987 percent for new sources (the control efficiency of the single 
best controlled source). Id. section 15.3.
    EPA continues to believe that this standard is consistent with the 
statute and applicable caselaw. First, the statutory language requiring 
floors to be based on ``best controlled'' (new) /``best performing'' 
(existing) does not specify whether ``best'' is to be measured on 
grounds of control efficiency or emission level. See Sierra Club v. 
EPA, 167 F.3d 658, 661 (`` `average emissions limitation achieved by 
the best performing 12 percent of units' * * * on its own says nothing 
about how the performance of the best units is to be calculated''). The 
requirement that the new source floor reflect ``emission control'' 
achieved in practice reinforces that the standard can be determined and 
expressed in terms of control efficiency. Existing floors determined 
and expressed in terms of control efficiency are likewise consistent 
with the requirement that the floor for existing sources reflect 
``average emission limitation achieved'', since ``emission limitation'' 
includes standards which limit the ``rate'' of emissions on a 
continuous basis--exactly what the standards do here. CAA section 
302(k). Moreover, where Congress wanted to express performance solely 
in terms of numerical limits, rather than performance efficiency, it 
said so explicitly. See CAA section 129(a)(4).
    The policy reason for EPA's interpretation here is that a standard 
limiting volumetric TCl emissions means that less product is produced, 
since these sources recover hydrogen chloride to produce hydrochloric 
acid. TSD Vol. III at 15-6; 70 FR at 59450. EPA does not believe that 
the MACT floor provisions should compel an otherwise best performing 
source to limit the amount of product it produces. See 2 Legislative 
History at 3352 (House Report) (``MACT is not intended to * * * drive 
sources to the brink of shutdown'').
    Moreover, all that is at issue here is how to express the 
performance of sources ranked as best performing under both EPA's 
methodology and under the Straight Emissions methodology. This is 
because, with one exception, the best performing sources are the same 
under EPA's methodology as those identified as best performing under 
the Straight Emissions methodology. TSD Vol. III App. C at E-HCLPF-CL 
and App. E at SO-HCLPF-CL. The one exception is where EPA chose a 
parallel test condition which exhibits more variability to characterize 
the source's performance (source 855 condition 11 rather than condition 
13), and consequently resulted in this source not being selected as a 
best performer. Given this documented variability, this is a reasonable 
choice. Thus, EPA is selecting as best performers those with the lowest 
measured emissions of chlorine, but chose to express their performance 
in terms of system removal efficiency to avoid impacts on amount of 
product these best performing sources produce. EPA continues to regard 
this choice as reasonable.
    EPA has carefully reexamined this standard in light of Brick MACT. 
The opinion does not address the issue directly, since no standard 
there was determined or expressed in terms of control efficiency. 
Moreover, as noted above, unlike section 129, section 112 contains no 
directive to express standards as numerical limits (see section 
129(a)(4)), further supporting EPA's view that it could reasonably 
choose to express this standard in per cent reduction terms. See also 
section 112(i)(5)(A), which allows sources that achieve early 
reductions based on measured rates of removal efficiency a reprieve 
from MACT, a provision reasonably read to allow section 112(d) 
performance to be expressed in terms of rate of removal efficiency.
    The opinion does hold, however, that different HAP levels in raw 
materials could not justify a conclusion that floor standards were 
unachievable, so that emissions attributable to raw material HAP had to 
be accounted for in the standard. 479 F.3d at 882-883. The TCl standard 
at issue here accounts for emissions from all HAP inputs, 70 FR at 
59450, and so does not present this deficiency. Nor are the floor 
standards designed to be achieved by all sources with a specific 
emission control technology. 479 F.3d at 880-81. The removal efficiency 
standard is not based on performance of any particular technology, and 
simply is the averaged (or single best) efficiencies of the best 
performing sources (after accounting for run-to-run variability).
    EPA, however, does not (subject to comment) believe that the 
alternative standard of 150 ppmv by volume for existing sources 
(section 63.1218 (a) (6) (i)) should be retained and EPA currently 
intends to seek remand of this alternative standard. The standard 
appears inconsistent with the SRE MACT standard, since it allows 
sources to operate with less efficient system removals.
    EPA also recognizes that certain parts of the rationale for the 
standard, generally related to whether standards are to reflect varying 
raw material HAP inputs, do not appear to be consistent with Brick 
MACT. EPA is making appropriate revisions to the key record documents, 
which are available in red line strike out versions in the 
administrative record.

D. Standards for Dioxins/Furans

    Polychlorinated dioxins and furans (D/F, or `dioxins') are 
typically not present in any of the inputs to hazardous waste 
combustion devices. Rather, they are formed post-combustion (often from 
some type of chlorinated precursor, which precursor is itself typically 
a product of incomplete combustion). 70 FR at 59461. As combustion 
efficiency increases, complex organic molecules which can be D/F 
precursors are oxidized to form carbon dioxide or carbon monoxide, 
helping to minimize D/F formation and emission. Id. Different levels of 
chlorine in waste or other inputs do not appreciably influence D/F 
emission rates. TSD Vol. IV \18\ section 3.3 (documenting that D/F 
formation and emission is ordinarily not dependent on feed levels of 
chlorinated

[[Page 54885]]

materials); TSD Vol. III at 10-6. Nor does burning hazardous waste 
generally have an appreciable impact on CDD formation and emissions, so 
that it is technically appropriate in some instances to consider D/F 
emission levels from sources which do not burn hazardous waste in 
evaluating emission potential from those that do. TSD Vol. III at 11-4 
and n. 72.
---------------------------------------------------------------------------

    \18\ USEPA, ``Technical Support Document for HWC MACT Standards, 
Volume IV: Compliance with the HWC MACT Standards'' (TSD Vol. IV), 
September 2005. See docket item EPA-HQ-OAR-2004-0022-0435.
---------------------------------------------------------------------------

    Precise formation and control mechanisms of D/Fs are thought to be 
fairly well understood for systems with dry air pollution control 
devices (or extensive ductwork containing particulates on surfaces, 
such as for certain lightweight aggregate kilns). For these systems, D/
Fs are formed on particles entrained in the control device by surface-
catalyzed reactions where entrained particulate matter provides the 
reaction surfaces.\19\ D/F formation can increase exponentially as gas 
temperatures increase from 400 [deg]F to 750 [deg]F.\20\ Formation 
mechanisms, or their degree, are less well understood for systems with 
wet air pollution control or no air pollution control systems, making 
it less certain how much D/F these sources may emit over time. TSD Vol. 
III pp. 10-5 to 6.
---------------------------------------------------------------------------

    \19\ USEPA, ``Draft Technical Support Document for HWC MACT 
Standards, Volume IV: Compliance with the HWC MACT Standards,'' 
March 2004, Section 3.0.
    \20\ To be clear, the dry air pollution control device does not 
control D/F emission (except insofar as some of the formed dioxins/
furans adsorb to particulate which is collected). Rather, the inlet 
to these devices serves as an agent for the actual formation of the 
chemical, to the availability of a surface catalyzed reaction which 
occurs under these conditions.
---------------------------------------------------------------------------

    EPA used the Straight Emissions methodology rather than the SRE 
Feed methodology as the starting point for calculating floors for D/F 
because dioxins/furans do not come from inputs (but rather are formed 
post-combustion), so that it is not possible to calculate system 
removal efficiencies (which is calculated from inputs and outputs). 
However, for a number of the source categories where best performers do 
not have dry air pollution control devices, EPA's professional judgment 
was that this methodology did not give an accurate assessment of the 
best performing sources' performance over time (i.e., the best 
performers' variability). This is because there are myriad factors that 
can affect D/F emissions for these sources \21\ and, unlike sources 
equipped with a dry emission control device where gas temperature at 
the inlet to the control device is generally the dominant factor 
affecting D/F emissions),\22\ there is no generic, dominant factor 
affecting emissions. In these instances, EPA consequently selected as 
best performers those sources which best minimized the formation of 
dioxin precursors by maintaining the most efficient combustion 
conditions, as measured by carbon monoxide (CO) or total hydrocarbon 
emissions (HC), as well as by destruction/removal of hardest-to-burn 
hazardous waste constituents at an efficiency of 99.99 percent. The 
floor standards for these sources consequently is either meeting a CO 
standard of 100 ppmv or an HC standard of 10 ppmv, plus demonstrating a 
destruction/removal efficiency (DRE) of 99.99 percent on the hardest-
to-combust hazardous constituents present in the hazardous waste. In 
instances where the interim standard applied to such sources, EPA used 
that standard as the measure of best performers' good combustion 
instead of quantified CO/HC and destruction/removal efficiency.
---------------------------------------------------------------------------

    \21\ Factors that can affect D/F emissions from sources with a 
wet control device or no control device include: Soot buildup on 
boiler tubes and presence of metals in the feed that can catalyze D/
F formation reactions. 70 FR at 59502.
    \22\ For sources with dry emission control devices, D/F 
emissions during the compliance tests EPA used to characterize 
emissions would generally be at the upper end of the range of normal 
operations. Because an operating limit is established on gas 
temperature at the inlet to the control device based on levels 
achieved during the compliance test, operators had the incentive to 
maximize gas temperatures while still complying with the D/F 
emission standard under part 266, subpart H (Sec.  266.104(e)).
---------------------------------------------------------------------------

    Our assessment of these standards, subject to comment, is:
1. Incinerators
    a. Dry Air Pollution Control Device Subcategory.\23\ EPA used the 
Straight Emissions approach to establish floor levels for existing and 
new sources for this subcategory. The existing source floor, calculated 
in this manner, was slightly higher than the interim standard, so the 
floor is capped at the level of the interim standard. TSD Vol. III p. 
10-4. The standard for new sources is based on the performance of the 
single lowest emitting source. Id. at 10-11. EPA believes this standard 
to be consistent with the statute and all applicable caselaw.
---------------------------------------------------------------------------

    \23\ EPA explained a number of times that it did not 
subcategorize incinerators by control device. Rather, the presence 
or absence of a dry air pollution device relates to differences in 
dioxin formation mechanisms and consequent dioxin emission levels. 
See e.g. 70 FR at 59467.
---------------------------------------------------------------------------

    b. Incinerators with Wet Air Pollution Control Systems or No Air 
Pollution Control Systems. For both new and existing sources, EPA 
selected the interim standard as the floor standard. Id. at 10-6 and 
10-11. EPA considered basing the floor on the performance of lowest 
emitters in single tests, but these sources had strikingly varied 
results in other tests, with one `best' performer (source 3016) having 
emissions over 1000 times greater than its previous test, and well in 
excess of the floor level established by EPA. TSD Vol. III at 10-6.\24\ 
Under these circumstances, EPA was unable to conclude that single test 
results adequately represented the sources' performance over time 
(i.e., their long term variability). TSD Vol. III at 10-6 (lowest 
emitters in single tests would prove unable to duplicate their 
performance in other tests due to their variability). Without a means 
to assess long-term performance, EPA used the interim standard as the 
measure of best performers' performance over time. Id. EPA continues to 
believe that this is a reasonable estimate of best performance, and 
that the standards are consistent with the statute and applicable 
caselaw.
---------------------------------------------------------------------------

    \24\ See also Note from Bob Holloway, USEPA, to Docket ID No. 
EPA-HQ-OAR-2004-0022 entitled ``Incinerators: Comparison of D/F 
Emissions Variability for Best Performers and Other Sources with Wet 
or No APCD,'' dated April 5, 2007.
---------------------------------------------------------------------------

2. Cement Kilns
    The calculated floor for existing cement kilns using the straight 
emissions approach was slightly higher (less stringent) than the low 
end of the interim standard (0.28 as opposed to 0.20 ng TEQ/dscm). 
However, available historical D/F emissions data for cement kiln best 
performers (other test conditions conducted at different times from 
cement kiln sources identified as best performing, which test 
conditions reflect temperature optimization) show that these sources 
performance considering run-to-run variability exceeded both the floor 
level calculated using the Straight Emissions methodology and the 
interim standard.\25\ In light of this documented variability, EPA 
considered the interim standard the more stringent and consequently 
used the interim standard (0.20 ng TEQ/dscm or 0.40 ng TEQ/dscm and a 
temperature of 400 [deg]F or less at the inlet of the dry air pollution 
control device) as the floor. The calculated floor for new cement kilns 
using the straight emissions approach was slightly higher (less 
stringent) than one part of the interim standard for new cement kilns 
(0.21 ng TEQ/dscm as opposed to 0.20 ng TEQ/dscm), and in addition, the 
lowest emitter in a single test condition (source 323B3) exhibited 
enormous variability in other

[[Page 54886]]

performance tests (see test condition 323C1; the other lowest emitters 
likewise showed significant variability in other tests (id.)) so EPA 
adopted the level of the interim standard as the MACT floor for new 
sources. TSD Vol. III p. 11-7. EPA believes that these standards are 
consistent with the statute and applicable caselaw.
---------------------------------------------------------------------------

    \25\ See data for test conditions 228C4, 403C4, and 404C3 in 
Note from Frank Behan, USEPA, to Docket ID No. EPA-HQ-OAR-2004-0022 
entitled ``Comparative D/F Data for the Cement Kiln Best 
Performers,'' dated August 23, 2007.
---------------------------------------------------------------------------

3. Lightweight Aggregate Kilns
    The calculated floors for existing and new lightweight aggregate 
kilns using the Straight Emissions approach were higher (less 
stringent) than the interim standard, so EPA adopted the level of the 
interim standard as the MACT floor for both existing and new sources. 
TSD Vol. III pp. 12-4 and 12-6. EPA continues to believe that this 
approach uses the best measure of evaluating the best sources and their 
level of performance, and that these standards are consistent with the 
statute and applicable caselaw.
4. Liquid Fuel Boilers
    a. Sources with Dry Air Pollution Control Devices. EPA used the 
Straight Emissions approach to establish a floor for existing liquid 
fuel boilers equipped with a dry air pollution control device, which 
yielded an extremely high standard of 3.3 ng TEQ/dscm.\26\ TSD Vol. III 
p. 13-7. The floor standard also includes an alternative based on 
meeting temperature control of 400[deg] F at the inlet to the dry air 
pollution control device. Id. EPA also adopted a beyond-the-floor 
standard for these sources which is (necessarily) more stringent than 
the level of the floor. Id. at 13-8. This beyond the floor standard 
would be ascertained identically whether or not the existing source 
floor included the temperature control alternative. EPA believes that 
this standard is consistent with section 112 (d) (2) of the statute, 
and that the floor is also consistent with the statute, but not of 
direct relevance given that the actual standard is beyond-the-floor.
---------------------------------------------------------------------------

    \26\ The basis for subcategorizing in this way is the same as 
for incinerators.
---------------------------------------------------------------------------

    For new sources, EPA adopted a floor standard of the lowest 
emitters' performance, or meeting temperature control of 400[deg] F or 
less at the inlet to the dry air pollution control device. Subject to 
comment, EPA does not believe that this standard accounts for all the 
factors that could influence dioxin emissions from new sources, see 
Brick MACT, 479 F.3d at 881-82, and therefore intends to seek a remand 
of the standard and further examine it in a subsequent rulemaking.
    EPA also recognizes that not all of the rationale adopted for these 
standards is consistent with Brick MACT, particularly discussions 
relating to whether sources other than those in the best performing 
half of the MACT pool of best performers could replicate best 
performers' level of performance. EPA has made appropriate edits to the 
key support documents which are available for comment in red line 
strikeout form in the administrative record.
    b. Sources with Wet or Without Air Pollution Control Equipment. EPA 
has decided (subject to comment) not to defend most of the dioxin 
standards for sources with wet air pollution control equipment or 
without air pollution control equipment.\27\ These include the 
standards for liquid fuel boilers with wet or no air pollution control 
systems and standards for hydrochloric acid production furnaces. EPA 
continues to adhere to its analysis that these sources experience 
enormous operating variability based on dioxin formation and control 
mechanisms which are uncertain and presently not quantifiable. However, 
based on the discussion at 70 FR 59202/2, EPA does not believe that it 
is certain that the promulgated standard based on quantified good 
combustion addresses all of the potential formation and control 
mechanisms for dioxins as required. See Brick MACT, 479 F.3d at 882-83; 
CKRC, 255 F.3d at 862-63. Moreover, the cited preamble discussion 
suggests that additional dioxin formation and control mechanisms can be 
quantified directionally, if not with exactitude. This again may not be 
consistent with Brick MACT, 479 F.3d at 883 (lack of data resulting in 
inability to quantify variability related to non-technology factors 
does not by itself justify by itself a less stringent floor standard). 
EPA intends to seek a remand (subject to consideration of public 
comment) and to investigate these issues further in subsequent 
rulemaking.
---------------------------------------------------------------------------

    \27\ For the same reasons, we will not defend the dioxin 
standards for solid fuel boilers.
---------------------------------------------------------------------------

E. Non-Dioxin Organic HAP

    Hazardous wastes contain non-dioxin organic HAP which are destroyed 
by effective combustion. Treatment of hazardous waste by destruction of 
organics is indeed the chief reason that there is a hazardous waste 
combustion industry. See 40 CFR 268.42. (RCRA treatment standards for 
organic hazardous wastes, reflecting application of Best Demonstrated 
Available Technology (see Hazardous Waste Treatment Council v. EPA, 886 
F.2d 355, 363-64 (D.C. Cir. 1989)), are invariably based on performance 
of combustion technology.) EPA adopted standards quantifying good 
combustion conditions for non-dioxin organic HAP emitted by liquid fuel 
boilers, solid fuel boilers, and hydrochloric acid production furnaces. 
The floor standards for these sources is either meeting a CO standard 
of 100 ppmv or an HC standard of 10 ppmv, plus demonstrating a 
destruction/removal efficiency (DRE) of 99.99 percent on the hardest-
to-combust hazardous constituents present in the hazardous waste. In 
the event a source chooses to comply with the 100 ppmv CO standard, it 
must also demonstrate that it is achieving 10 ppmv HC standard in a 
single performance test, and establish continuously monitored 
parameters reflecting the conditions of that performance test 
(including operating temperature, maximum feed rates, minimum 
combustion zone residence time, and operating requirements on the 
hazardous waste firing system that optimize liquid waste atomization 
efficiency). Sections 63.1216(a)(5), 63.1217(a)(5), and 63.1218(a)(5).
    The basis for these standards is that good combustion, as measured 
by 100 ppmv CO or 10 ppmv HC, plus meeting 99.99 percent DRE, is the 
best measure of the performance over time of best performers. However, 
in contrast to dioxin, EPA has more knowledge of formation mechanisms 
and means of control over time. Non-dioxin organics (of which there are 
over 100 on the list of HAP) can be present in hazardous waste (or 
other inputs) or can be formed as products of incomplete combustion. 
Organics are destroyed when wastes are combusted, and best performers 
are those which destroy organics through the most efficient combustion. 
70 FR at 59463; see also Horsehead Resource Development v. Browner, 16 
F.3d 1246, 1265 (D.C. Cir. 1994) (``A kiln's utility as a means of 
destroying hazardous wastes turns on its ability to fully destroy them. 
In practice, destruction of hazardous wastes in the fuel is a function 
of the combustion efficiency of the kiln: Under poor conditions of 
efficiency, the principal organic hazardous constituents * * * of the 
toxic organic compounds contained in the hazardous waste fuel will be 
only partially broken down, thereby increasing the production of 
[products of incomplete combustion]'').
    Furthermore, 100 ppmv CO or 10 ppmv HC are long-recognized levels 
representing good combustion conditions. 70 FR 59463-464 (explaining 
further that lower levels are unlikely to be associated with good 
combustion and so no longer serve as a

[[Page 54887]]

measure of organic destruction). EPA adopted these levels here as the 
best measure of the sources' long-term performance (and reiterates that 
finding here). Id. and TSD Vol. III at 13-35, 14-26, and 15-9. In 
addition to good combustion being the long-recognized metric for 
organic destruction and performance, EPA lacked any data on individual 
organic HAP emissions from these devices, so had no choice but to use 
some type of surrogate to evaluate sources' performance.
    EPA views these standards as consistent with the statute and 
applicable caselaw. Regarding use of the quantified good combustion 
surrogate, the D.C. Circuit has held repeatedly that EPA may select a 
surrogate for control of HAP in adopting section 112(d) standards. See, 
e.g. National Lime Ass'n v. EPA, 233 F.3d 625, 639 (D.C. Cir. 2000); 
Sierra Club v. EPA (``Primary Copper MACT''), 353 F.3d 976, 984-85 
(D.C. Cir. 2004). EPA has shown here a valid basis for choosing good 
combustion as a surrogate: There is a strong correlation between 
optimized combustion conditions and minimized organic emissions in that 
oxidation of heavier, more complex organic molecules will be maximized 
when combustion conditions are optimized, thus minimizing emission of 
organics. 70 FR at 59463; see also id. at 59461-62; see also National 
Lime, 233 F.3d at 639 (upholding EPA's selection of PM as a surrogate 
for HAP metals where EPA demonstrated a correlation between removal of 
PM and metal HAP, and further holding both that EPA need not quantify 
the precise amount of metal HAP removed, and that the amount of HAP 
metal removed may vary); Primary Copper MACT, 353 F.3d at 984. EPA has 
further demonstrated the reasonableness of 100 ppmv CO or 10 ppmv HC as 
measures of good combustion.
    National Lime further indicates (in dicta) that choice of a 
surrogate may not be valid if emissions of the HAP could increase by 
some mechanism for which the surrogate fails to account, specifically 
noting that if HAP metal feedrates decreased and PM emissions did not 
decrease proportionately, PM might not be a valid surrogate. 233 F.3d 
at 639. This discussion has no direct factual applicability here since 
organic emissions are not input dependent. See also Primary Copper 
MACT, 353 F.3d at 985 (rejecting argument that input variability made 
PM an arbitrary surrogate for metals). The situation here is similar to 
that in Mossville, where the court held that EPA could account for best 
performers' performance over time, and could estimate performance over 
time by some means other than emission levels. 370 F.3d at 1242. The 
difference here is that EPA is using a quantified surrogate to do so, 
but EPA believes this is a difference without legal significance given 
the reasonableness of the surrogate on the facts presented here. 
Indeed, EPA selected here an existing regulatory standard as a measure 
of best performers' performance over time (RCRA standards for CO/HC and 
DRE), just as in Mossville EPA selected the existing uniform vinyl 
chloride regulatory standard as that measure. 370 F.3d at 1240.\28\
---------------------------------------------------------------------------

    \28\ Brick MACT holds that EPA may not select floor standards to 
assure that all sources in the category will be able to meet the 
standards. 479 F.3d at 880-81. EPA did not do so here. The CO/HC and 
DRE standards are EPA's best estimate of best performers' 
performance over time. As in Mossville, EPA selected an existing 
regulatory limit not because all sources were (by definition) 
meeting that regulatory limit, but because no other means of 
accurately assessing variability were available. 370 F.3d at 1240. 
Moreover, sources will establish parametric monitoring conditions, 
which will vary by source, as part of the process of meeting the 10 
ppmv HC standard, so the standards in fact are not uniform across 
the source category.
---------------------------------------------------------------------------

    One commenter maintained that CO/HC standards should be numerically 
lower to reflect lowest CO/HC emissions, and further maintained that CO 
and HC are not the sole measures of organic combustion efficiency, 
which, as EPA noted, can be influenced by such factors as inadequate 
time, temperature and turbulence within individual combustion zones, 
and, the argument goes, are therefore improper or inadequate 
surrogates. 70 FR at 59463/2; cf. National Lime, 233 F.3d at 639. EPA 
addressed these issues in the record. 70 FR at 59462-63. With respect 
to the level for CO/HC, extremely low CO floors are unlikely to be met 
at all times by best performers due to all the potential minor sources 
of variability. So the 100 ppmv standard--which must be met 
continuously (and is measured by a continuous emission monitor), is the 
best measure of best performers' variability and hence performance over 
time. TSD Vol. III at 13-35, 14-26 and 15-9 (best sources' inability to 
duplicate a lower level of performance at all times for these reasons); 
see also Mossville, 370 F.3d at 1242 (if floor standard must be met 
continuously, then the best performers' maximum variability must be 
reflected in that standard). Of equal importance, lower levels of 
either CO or HC are no longer likely to be associated with increased 
organic destruction efficiency. 70 FR at 59462-64 (CO itself is a 
conservative indicator of combustion efficiency because it is a 
thermally stable, refractory compound which is the final stage of the 
combustion process of an organic molecule, and levels lower than 100 
ppmv are no longer reliably associated with levels of organic HAP). 
Finally, the factors mentioned by the commenter which can influence 
organic destruction are in fact encompassed within the CO and HC 
standards because, as EPA explained, sources must conduct a performance 
test for HC and DRE, and continuously monitored parameters, including 
minimum operating temperature, maximum feed rates, minimum combustion 
zone residence time, and operating requirements on hazardous waste 
firing systems (i.e., all of the factors mentioned by the commenter), 
are established based on the conditions established in that performance 
test. 70 FR at 59464/1. EPA consequently views all of these standards 
as consistent with Brick MACT and the statute.
    Edited versions of the key support documents for this standard, 
edited to reflect changes necessary in light of Brick MACT, are 
available in red line strike out format for comment in the 
administrative record.

F. Mercury

1. Incinerators
    For existing incinerators, both the SRE/Feed methodologies and 
straight emissions methodologies (even without calculation of run-to-
run variability) produced floors which were higher than the interim 
standard. TSD Vol. III appendices C and E, tables E-INC-HG CT and SF-
INC-HG, respectively. EPA's decision to use the interim standard as the 
level of the floor consequently does not raise issues vis-[aacute]-vis 
Brick MACT. See also Mossville, 370 F.3d at 1241-42 (selection of 
regulatory standard as floor is a legitimate means of assessing best 
performers' variability when these performers demonstrably emit at a 
level close to that regulatory level).
    For new incinerators, EPA selected the emission level of the lowest 
emitting source since the same source was the lowest emitter under both 
the SRE methodology and the Straight Emissions methodology, TSD Vol. 
III appendices C and E, tables E-INC-HG CT and SF-INC-HG, respectively, 
again raising no issues vis-[aacute]-vis Brick MACT.
2. Cement Kilns
    For both new and existing cement kilns, the mercury floor standard 
appears inconsistent with the Brick MACT opinion and the statute 
because it is based in whole or in substantial part on emissions 
attributable exclusively to hazardous waste control. The standard thus 
does not result in control of all mercury which could be

[[Page 54888]]

emitted by cement kilns (mercury in raw materials being the notable 
example), and so appears to require revision. 479 F.3d at 882-83. 
Subject to comment, it is thus EPA's intent to amend this standard and 
to seek remand of the standard.
3. Lightweight Aggregate Kilns
    The methodology for developing floor standards for mercury for 
lightweight aggregate kilns is essentially a Straight Emissions 
approach for mercury contributed by hazardous waste.\29\ The floor 
calculated thereby produced existing and new source floors higher than 
the interim standard of 120 [mu]g/dscm total mercury emissions (110 
[mu]g/dscm for new sources), which EPA therefore adopted as the floor 
standard. TSD Vol. III at 12-8 to 9, 12-12 and section 7.2.3.5. EPA 
continues to believe that the interim standard remains the best measure 
of best sources' performance given the available data. However, the 
interim standard contains a compliance option based solely upon mercury 
emissions attributable to hazardous waste. Section 63.1206(b)(15). 
Subject to comment, this alternative compliance mechanism appears to be 
inconsistent with Brick MACT since it would not control all mercury 
emitted by the kiln. 479 F.3d at 882-83; see also section III.B.3 
above. Subject to consideration of public comment, EPA intends to seek 
a remand of this alternative standard and to consider this issue 
further in subsequent rulemaking.
---------------------------------------------------------------------------

    \29\ EPA used the Straight Emissions approach here for data-
specific reasons explained at section 7.5.3.2 of Volume III of the 
TSD.
---------------------------------------------------------------------------

4. Liquid Fuel Boilers
    a. Higher Heating Value Hazardous Wastes Subcategory. The mercury 
floor standard for this subcategory for both existing and new sources 
accounts only for mercury emissions from hazardous waste. TSD Vol. III 
pp. 13-14 and 13-16. These standards thus appear to require revision, 
and EPA accordingly currently expects to seek remand of this standard. 
Brick MACT, 479 F.3d at 882-83.
    b. Lower Heating Value Hazardous Wastes Subcategory. The mercury 
floor standard for this subcategory for both existing and new sources 
is based on the Straight Emissions methodology. TSD Vol. III at 13-16 
and 13-18; see also 69 FR 21286-87 (because so many of the data 
measurements were non-detects, EPA was unable to calculate removal 
efficiencies, and so did not use the SRE Feed methodology). The 
standard also applies to all mercury emitted by the source, not just 
that attributable to hazardous waste. Section 63.1217(a)(2)(i). EPA 
does not believe that this approach creates any issues vis-[aacute]-vis 
Brick MACT.
5. Solid Fuel Boilers
    EPA used the SRE Feed methodology to identify best sources and 
their level of performance for both new and existing solid fuel 
boilers. TSD Vol. III at 14-7, 14-9. The floor standards are identical 
to those using the Straight Emissions methodology because the best 
performing sources (and single best performing source) are the same 
under either methodology. TSD Vol. III at App. C (E-SFB-HG-CT) and E 
(SF-SFB-HG). EPA does not believe that these standards pose issues vis-
[aacute]-vis Brick MACT.

G. Normalization

    A number of the standards are ``normalized,'' that is expressed as 
a given amount of pollutant per amount of some production related 
parameter such as air flow or thermal inputs. See generally 70 FR at 
59451. Most technology-based standards are expressed in terms of some 
type of normalizing parameter in order to allow meaningful comparison 
between performance of different sources. Weyerhaeuser v. Costle, 590 
F.2d 1011, 1059 (D.C. Cir. 1978). As EPA pointed out, comparing 
unnormalized performance is like asking which baseball pitcher is the 
better performer, the one who has given up 6 earned runs or the one who 
has given up 20. Unless and until the figure is normalized over 9 
innings pitched, the question is meaningless. 70 FR at 59451 n. 101.
    EPA sees nothing in the statute which precludes use of 
normalization in determining who best performers are for purposes of 
MACT floor determinations. Section 112(d)(3) does not specifically 
address the issue (the terms ``best performing'' and ``best 
controlled'' being amenable to an interpretation allowing comparisons 
of normalized emissions to assess which source is ``better'' or 
``best''). The issue of normalization was not presented in Brick MACT, 
so that EPA likewise does not view the opinion as precluding the 
approach.

H. Potential Implications to the Compliance Date Provisions if 
Standards Are Remanded to EPA

    The compliance date of the final rule is October 14, 2008. As 
discussed above, we are contemplating requesting the Court to remand 
several standards so that we can reexamine them in a future rulemaking, 
a process that likely would be concluded well after the compliance date 
of the rule. It is not our intent to ask the Court to vacate any 
standards, including those standards that may have to be revised in a 
future rulemaking. As a result, sources would need to comply with the 
standards promulgated in October 2005 according to the compliance date 
provisions codified under Sec.  63.1206(a). See NRDC v. EPA, 489 F.3d 
1364, 1373-74 (D.C. Cir. 2007).

List of Subjects in 40 CFR Part 63

    Environmental protection, Air pollution control, Hazardous 
substances, Reporting and recordkeeping requirements.

    Dated: September 21, 2007.
Stephen L. Johnson,
Administrator.
[FR Doc. E7-19097 Filed 9-26-07; 8:45 am]
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