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Rule2026-04646

Standards of Performance for New Stationary Sources and Emission Guidelines for Existing Sources: Large Municipal Waste Combustors Voluntary Remand Response and Five-Year Review

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Published

March 10, 2026

Effective

May 11, 2026

Issuing agencies

Environmental Protection Agency

Abstract

The U.S. Environmental Protection Agency (EPA) is finalizing new source performance standards (NSPS) and emission guidelines (EG) for the large municipal waste combustion (MWC) source category. This final rule responds to a voluntary remand of the preceding rule for this source category and announces the results of the non-discretionary review at five-year intervals required by Clean Air Act (CAA) section 129(a)(5), fulfilling the requirements of a consent decree for the source category. The final rule revises the remanded emission limits for cadmium, lead, particulate matter, polychlorinated dibenzodioxins and dibenzofurans, mercury, hydrogen chloride, and sulfur dioxide for all sources subject to the NSPS and EG and the remanded emission limits for nitrogen oxides and carbon monoxide for some sources subject to the EG and all sources subject to the NSPS. This final rule also removes certain startup, shutdown, and malfunction (SSM) exclusions and exemptions. In addition, the EPA is taking this opportunity to streamline regulatory language; revise recordkeeping and reporting requirements; establish electronic notification; reestablish new and existing source applicability dates; eliminate title V requirements for air curtain incinerators that burn only wood waste, yard waste, and clean lumber; close a 2007 proposed reconsideration action; and make certain typographical and technical corrections and clarifications. The EPA estimates this final rule will result in 3,269 tpy reduction in regulated pollutants from existing sources through implementation of the final emission limits.

Full Text

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[Federal Register Volume 91, Number 46 (Tuesday, March 10, 2026)]
[Rules and Regulations]
[Pages 11802-11887]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 2026-04646]

[[Page 11801]]

Vol. 91

Tuesday,

No. 46

March 10, 2026

Part IV

Environmental Protection Agency

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40 CFR Part 60

Standards of Performance for New Stationary Sources and Emission
Guidelines for Existing Sources: Large Municipal Waste Combustors
Voluntary Remand Response and Five-Year Review; Final Rule

Federal Register / Vol. 91 , No. 46 / Tuesday, March 10, 2026 / Rules
and Regulations

[[Page 11802]]

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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 60

[EPA-HQ-OAR-2017-0183; FRL-5120-04-OAR]
RIN 2060-AO18

Standards of Performance for New Stationary Sources and Emission
Guidelines for Existing Sources: Large Municipal Waste Combustors
Voluntary Remand Response and Five-Year Review

AGENCY: Environmental Protection Agency (EPA).

ACTION: Final rule.

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SUMMARY: The U.S. Environmental Protection Agency (EPA) is finalizing
new source performance standards (NSPS) and emission guidelines (EG)
for the large municipal waste combustion (MWC) source category. This
final rule responds to a voluntary remand of the preceding rule for
this source category and announces the results of the non-discretionary
review at five-year intervals required by Clean Air Act (CAA) section
129(a)(5), fulfilling the requirements of a consent decree for the
source category. The final rule revises the remanded emission limits
for cadmium, lead, particulate matter, polychlorinated dibenzodioxins
and dibenzofurans, mercury, hydrogen chloride, and sulfur dioxide for
all sources subject to the NSPS and EG and the remanded emission limits
for nitrogen oxides and carbon monoxide for some sources subject to the
EG and all sources subject to the NSPS. This final rule also removes
certain startup, shutdown, and malfunction (SSM) exclusions and
exemptions. In addition, the EPA is taking this opportunity to
streamline regulatory language; revise recordkeeping and reporting
requirements; establish electronic notification; reestablish new and
existing source applicability dates; eliminate title V requirements for
air curtain incinerators that burn only wood waste, yard waste, and
clean lumber; close a 2007 proposed reconsideration action; and make
certain typographical and technical corrections and clarifications. The
EPA estimates this final rule will result in 3,269 tpy reduction in
regulated pollutants from existing sources through implementation of
the final emission limits.

DATES: This final rule is effective on May 11, 2026. The incorporation
by reference (IBR) of certain publications listed in the rule is
approved by the Director of the Federal Register as of May 11, 2026.

ADDRESSES: The EPA has established a docket for this action under
Docket ID No. EPA-HQ-OAR-2017-0183. All documents in the docket are
listed at <a href="https://www.regulations.gov">https://www.regulations.gov</a>. Although listed, some
information is not publicly available, e.g., Confidential Business
Information (CBI) or other information whose disclosure is restricted
by statute. The EPA does not place certain other material, such as
copyrighted material, on the internet; this material is publicly
available only as Portable Document Format (PDF) versions accessible
only on the EPA computers in the docket office reading room. The public
cannot download certain databases and physical items from the docket
but may request these items by contacting the docket office at 202-566-
1744. The docket office has 10 business days to respond to such
requests. With the exception of such material, publicly available
docket materials are available electronically at <a href="https://www.regulations.gov">https://www.regulations.gov</a>.

FOR FURTHER INFORMATION CONTACT: For information about this final rule,
contact Ms. Noel Cope, Natural Resources Division, 109 T.W. Alexander
Drive, P.O. Box 12055, Research Triangle Park, North Carolina 27711;
telephone number: (919) 541-2128; and email address: <a href="/cdn-cgi/l/email-protection#edae829d88c3a3828881ad889d8cc38a829b">[email&#160;protected]</a>.

SUPPLEMENTARY INFORMATION:
Preamble acronyms and abbreviations. Throughout this notice the use
of ``we,'' ``us,'' or ``our'' refers to the EPA. We use multiple
acronyms and terms in this preamble. While this list may not be
exhaustive, to ease the reading of this preamble and for reference
purposes, the EPA defines the following terms and acronyms here:

ANSI American National Standards Institute
APCD air pollution control device
ASME American Society of Mechanical Engineers
ASNCR advanced selective noncatalytic reduction
ATSDR Agency for Toxic Substances and Disease Registry
BSER Best system of emission reduction
CAA Clean Air Act
CBI Confidential Business Information
Cd cadmium
CDX Central Data Exchange
CEDRI Compliance and Emissions Data Reporting Interface
CEMS continuous emissions monitoring system
CFBS circulating fluidized bed scrubber
CFR Code of Federal Regulations
CISWI Commercial and Industrial Solid Waste Units
CO carbon monoxide
CRA Congressional Review Act
DCOT digital camera opacity technique
Dscm dry standard cubic meter
EAV equivalent annualized value
EG emission guidelines
EPA Environmental Protection Agency
ERT Electronic Reporting Tool
HAP hazardous air pollutant(s)
HCl hydrogen chloride
Hg mercury
HMIWI hospital, medical, and infectious waste incinerators
ICR Information Collection Request
LN\TM\ Low NO<INF>X</INF>
LPL lower predictive limit
MACT maximum achievable control technology
MB/RC mass burn rotary combustor
MB/WW mass burn water wall
mg milligram
MSW municipal solid waste
MWC municipal waste combustor
NAAQS National Ambient Air Quality Standards
NAICS North American Industry Classification System
ng nanogram
NO<INF>X</INF> oxides of nitrogen (nitrogen oxides)
NRDC Natural Resources Defense Council
NSPS new source performance standards
NTTAA National Technology Transfer and Advancement Act
O<INF>3</INF> Ozone
OCAP Office of Clean Air Programs
OTR Ozone Transport Region
OMB Office of Management and Budget
Pb lead
PCDD/PCDF polychlorinated dibenzodioxins and dibenzofurans (dioxins/
furans)
PDF portable document format
PM particulate matter
ppm parts per million
ppmvd parts per million by volume, dry basis
PRA Paperwork Reduction Act
PV present value
QRO Certification for Municipal Solid Waste Combustion Facilities
Operator
RATA relative accuracy test audit
RDL representative detection level
RDF/FBC refuse-derived fuel fluidized bed combustor
RDF/S refuse-derived fuel stoker combustor
RDF/SS refuse-derived fuel semi-suspension or spreader stoker wet
process conversion combustor
RFA Regulatory Flexibility Act
RIA Regulatory Impact Analysis
SCR selective catalytic reduction
SNCR selective noncatalytic reduction
SO2 sulfur dioxide
SSM startup, shutdown, and malfunction
tpd tons per day
tpy tons per year
[micro]g microgram
UMRA Unfunded Mandates Reform Act of 1995
UPL upper prediction limit
VCS voluntary consensus standards
WTEA Waste to Energy Association
XML Extensible Markup Language

Table of Contents

I. General Information
A. Executive Summary
B. Does this action apply to me?

[[Page 11803]]

C. Where can I get a copy of this document and other related
information?
D. Judicial Review and Administrative Reconsideration
II. Background
A. What is the statutory authority for this action?
B. What is the regulatory background for the large MWC source
category, and how do the NSPS and EG regulate emissions from the
source category?
C. What changes did we propose for the large MWC source category
in our January 23, 2024, proposal?
D. What outreach did we conduct following the proposal?
III. What is included in these final rules?
A. What are the final rule amendments based on the five-year
review and response to the voluntary MACT floor remand for the large
MWC source category?
B. What are the final rule amendments addressing emissions
during periods of startup, shutdown, and malfunction?
C. What are the final rule amendments addressing other changes
to the large MWC EG and NSPS?
D. What are the effective and compliance dates of the standards?
E. Severability
IV. What is the rationale for our final decisions and amendments for
the large MWC source category?
A. Five-Year Review and Response to the Voluntary MACT Floor
Remand for the Large MWC Source Category
B. Startup, Shutdown, and Malfunction
C. Other Changes to the Large MWC EG and NSPS
V. Summary of Cost, Environmental, Economic Impacts, and Additional
Analyses Conducted
A. What are the affected facilities?
B. What are the air quality impacts?
C. What are the cost impacts?
D. What are the economic impacts?
E. What are the benefits?
F. What analysis of children's environmental health did we
conduct?
VI. Statutory and Executive Order Reviews and 1 CFR Part 51
A. Executive Order 12866: Regulatory Planning and Review and
Executive Order 13563: Improving Regulation and Regulatory Review
B. Executive Order 14192: Unleashing Prosperity Through
Deregulation
C. Paperwork Reduction Act (PRA)
D. Regulatory Flexibility Act (RFA)
E. Unfunded Mandates Reform Act (UMRA)
F. Executive Order 13132: Federalism
G. Executive Order 13175: Consultation and Coordination With
Indian Tribal Governments
H. Executive Order 13045: Protection of Children From
Environmental Health Risks and Safety Risks
I. Executive Order 13211: Actions Concerning Regulations That
Significantly Affect Energy Supply, Distribution, or Use
J. National Technology Transfer and Advancement Act (NTTAA) and
1 CFR Part 51
K. Congressional Review Act (CRA)

I. General Information

A. Executive Summary

In December 1995, the EPA adopted emissions guidelines (EG) (40 CFR
part 60, subpart Cb) and new source performance standards (NSPS) (40
CFR part 60, subpart Eb) for large municipal waste combustors (MWC),
which have a combustion capacity of greater than 250 tons per day (tpd)
of municipal solid waste (MSW), pursuant to Clean Air Act (CAA) section
129.\1\ CAA section 129(a)(5) requires review of these standards at 5-
year intervals and, in 2006, the EPA promulgated amendments to the 1995
standards, revising the emission limits and compliance testing
provisions to reflect the actual performance achieved by existing MWCs
and improvements in CEMS data performance and reliability.\2\
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\1\ Note that on February 11, 1991, Subpart Ea was promulgated
that applies Standards of Performance to MWCs which commenced
construction after December 20, 1989, and on or before September 20,
1994.
\2\ 71 FR 27324 (May 10, 2006).
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Following promulgation of the 2006 rulemaking, environmental groups
filed a petition for review in the D.C. Circuit challenging the
rulemaking. The petitioners challenged the emission limits which the
EPA promulgated in 1995. In light of then-recent precedents casting
doubt on the soundness of emission limits derived in part from state-
issued air permits as the 1995 emission limits for large MWCs were, the
EPA sought a voluntary remand of the 2006 rule.\3\ In its remand
motion, the EPA announced its intention to grant the environmental
groups' administrative petition to revisit the 1995 emission limits and
reevaluate the 2006 rule as necessary to comport with any revisions.
The D.C. Circuit issued an order granting the EPA's request for a
remand in 2008, which directed the EPA to review its 2006
rulemaking.\4\
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\3\ Specifically, the petitioners pointed to a 2004 decision
from the D.C. Circuit, which remanded MACT floors established for
existing small MWCs derived from state-issued permit limits because
the Court found the EPA did not fulfill the requirement of CAA
section 129(a)(2) in setting the floors. See Northeast Maryland
Waste Disposal Authority v. EPA, 358 F.3d 936 (D.C. Cir. 2004).
Additionally, the EPA noted in its motion for a voluntary remand
that since the time the EPA finalized the 2006 rulemaking, the D.C.
Circuit issued three decisions that were relevant to rules
promulgated under sections 112 and 129 of the CAA, since the floor
setting requirements in section 129 are essentially equivalent to
those under section 112. See Sierra Club v. EPA, 479 F.3d 875 (D.C.
Cir. Mar. 13, 2007) (vacating the EPA's regulations setting national
emission standards for brick and clay ceramics kilns under Section
112); Natural Resources Defense Council v. EPA, 489 F.3d 1250 (D.C.
Cir. June 8, 2007) (vacating the EPA's regulations setting national
emission standards under section 112 for hazardous air pollutants
from industrial, commercial, and institutional boilers and process
heaters and the EPA's regulations under section 129 defining the
term ``commercial and industrial solid waste incineration unit'');
Natural Resources Defense Council v. EPA, 489 F.3d 1364 (D.C. Cir.
June 19, 2007) (vacating portions of an EPA rule promulgated under
CAA section 112 regulating hazardous air pollutants from the
manufacture of plywood and composite wood products).
\4\ Order, Sierra Club v. EPA, No. 06-1250 (D.C. Cir. filed Feb.
15, 2008).
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In 2024, the EPA proposed to revise the NSPS and EG under CAA
section 129 for large MWCs by amending existing standards for the large
MWC source category.\5\ The Agency sought comment on additional data,
including data on the number of facilities that would require retrofit
to meet any emission limits and data to inform the EPA's projections of
air pollution control device (ACPD) use by large MWCs. In addition, the
EPA sought comment on developments in practices, processes, and control
technologies that reduce pollutant emissions.
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\5\ 89 FR 4243 (Jan. 23, 2024).
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In 2025, the Agency reopened the comment period for an additional
four months to gather additional information on the proposed amendments
to the large MWC regulations.\6\ Specifically, the EPA sought
additional information and documentation on verifiable historic
pollutant emission concentration information (e.g., stack test reports,
waste characterization reports and continuous emission monitor records)
for large MWCs so that we could further assess the proposed maximum
achievable control technology (``MACT'') requirements, including
operation of the control technologies over time.
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\6\ 90 FR 4708 (Jan. 8, 2025).
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In this final rule, the EPA is revising the remanded emission
limits for cadmium, lead, particulate matter, polychlorinated
dibenzodioxins and dibenzofurans, mercury, hydrogen chloride, and
sulfur dioxide for all sources subject to the NSPS and EG and the
remanded emission limits for nitrogen oxides and carbon monoxide for
some sources subject to the EG and all sources subject to the NSPS. The
EPA is also finalizing the following amendments: removal of SSM
exclusions and exemptions; streamlined regulatory language; revisions
to recordkeeping and reporting requirements; addition of electronic
reporting requirements; reestablishment of new and existing source
applicability dates; elimination of title V requirements for air
curtain incinerators that burn only wood waste, yard waste, and clean
lumber and are not located at a major source or subject to title V for

[[Page 11804]]

other reasons; closing the 2007 proposed reconsideration action; and
other technical, typographical, and clarifying corrections to certain
provisions in the NSPS and EG.
Following consideration of comments and additional information
received on the proposed rule and the reopened comment period, the EPA
is revising its reassessment of the MACT floor limits for the EG and
NSPS. The EPA is finalizing an approach similar to that in the proposed
rule, using separate methodologies for pollutants with stack test data
(Cd, Pb, Hg, PM, HCl, and PCDD/PCDF) and pollutants with CEMS data (or
CEMS pollutants) (CO, NO<INF>X</INF>, and SO<INF>2</INF>). The final
limits incorporate new data submitted during the reopened comment
period for years 1990 to 1995 in addition to the 2000 to 2009
compliance dataset that the EPA used for the proposed limits.
The EPA estimates that this final rule will result in present value
costs of $330 million at a three percent discount rate and $210 million
at a seven percent discount rate over the 2030 to 2049 time frame, with
equivalent annualized values of $25 and $28 million per year,
respectively (in 2024 dollars, discounted to 2025).

B. Does this action apply to me?

Regulated entities. This final action applies to large MWCs that
combust more than 250 tons per day (tpd) of municipal solid waste (MSW)
as defined under CAA section 129(a)(1)(B), to be regulated under title
40 of the Code of Federal Regulations (CFR) part 60, new subparts VVVV
and WWWW. Table 1 of this preamble presents categories and entities
that this action potentially regulates.

Table 1--Industrial Source Categories Affected by This Final Action
------------------------------------------------------------------------
Category NAICS * code
------------------------------------------------------------------------
Solid Waste Combustors and Incinerators................. 562213
Administration of Air and Water Resource and Solid Waste 924110
Management Programs....................................
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The EPA does not intend Table 1 of this preamble to be exhaustive
but rather to provide a guide for readers regarding entities that this
final action likely affects. To determine whether this action affects
your facility, you should examine the applicability criteria found in
title 40 of the Code of Federal Regulations (CFR), 40 CFR 60.5690 of
subpart VVVV and 40 CFR 60.6300 of subpart WWWW. If you have questions
regarding the applicability of any aspect of the final subparts to a
particular entity, please contact the appropriate person listed in the
preceding FOR FURTHER INFORMATION CONTACT section of this preamble.

C. Where can I get a copy of this document and other related
information?

In addition to the docket, an electronic copy of this final action
will be available on the internet. In accordance with 5 U.S. Code
(U.S.C.) 553(b)(4), a brief summary of this rule may be found at
<a href="https://www.regulations.gov">https://www.regulations.gov</a>, Docket ID No. EPA-HQ-OAR-2017-0183.
Following signature by the Administrator, the EPA will post a copy of
this final action at <a href="https://www.epa.gov/stationary-sources-air-pollution/large-municipal-waste-combustors-lmwc-new-source-performance">https://www.epa.gov/stationary-sources-air-pollution/large-municipal-waste-combustors-lmwc-new-source-performance</a>.
Following publication in the Federal Register, the EPA will post the
Federal Register version and key technical documents at this same
website.

D. Judicial Review and Administrative Reconsideration

Under CAA section 307(b)(1), judicial review of this final action
is available only by filing a petition for review in the U.S. Court of
Appeals for the D.C. Circuit (``D.C. Circuit'') by May 11, 2026. CAA
section 307(b)(2) prohibits a party from challenging this final action
separately in any civil or criminal proceedings for enforcement.
CAA section 307(d)(7)(B) further provides that only an objection to
a rule or procedure that was raised with reasonable specificity during
the period for public comment (including any public hearing) may be
raised during judicial review. This section also requires the EPA to
reconsider the rule if the person raising an objection can demonstrate
to the Administrator that it was impracticable to raise such objection
within the period for public comment or if the grounds for such
objection arose after the period for public comment (but within the
time specified for judicial review) and if such objection is of central
relevance to the outcome of the rule. Any person seeking to make such a
demonstration should submit a Petition for Reconsideration to the
Office of the Administrator, U.S. EPA, Room 3000, WJC South Building,
1200 Pennsylvania Ave., NW, Washington, DC 20460, with a copy to both
the person(s) listed in the preceding FOR FURTHER INFORMATION CONTACT
SECTION and the Associate General Counsel for the Air and Radiation Law
Office, Office of General Counsel (Mail Code 2344A), U.S. EPA, 1200
Pennsylvania Ave. NW, Washington, DC 20460.

II. Background

A. What is the statutory authority for this action?

CAA section 129 provides the statutory authority for this action.
CAA section 129(a)(1) requires the EPA to establish NSPS and EG
pursuant to CAA sections 111 and 129 for new and existing solid waste
incineration units, including ``incineration units with capacity
greater than 250 tons per day combusting municipal waste.'' \7\ This
final rule includes a reevaluation of the first-stage technology-based
standards established in 1995 pursuant to CAA section 129(a)(2) in
response to a voluntary remand by the D.C. Circuit. In addition, this
action includes a review of the reevaluated standards pursuant to CAA
section 129(a)(5), which requires that the EPA, at five-year intervals
review and, ``in accordance with [section 129 and section 111],'' \8\
revise the standards and the requirements promulgated for a category
solid waste incineration units, including large MWC units.
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\7\ 42 U.S.C. 7429(a)(1)(A)-(B).
\8\ Id. 7429(a)(5).
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CAA section 129(a)(2) provides that standards ``applicable to solid
waste incineration units promulgated under [section 111] and this
section shall reflect the maximum degree of reduction in emissions of
[certain listed air pollutants] that the Administrator, taking into
consideration the cost of achieving such emission reduction and any
non-air quality health and environmental impacts and energy
requirements, determines is achievable for new and existing units in
each category.'' \9\ This level of control is referred to as a maximum
achievable control technology (MACT) standard. CAA section 129(a)(4)
further directs the EPA to set numeric emission limits for certain
pollutants: cadmium (Cd),

[[Page 11805]]

mercury (Hg), lead (Pb), particulate matter (PM), hydrogen chloride
(HCl), sulfur dioxide (SO<INF>2</INF>), polychlorinated dibenzodioxins
and dibenzofurans (PCDD/PCDF), carbon monoxide (CO), and oxides of
nitrogen (NO<INF>X</INF>).\10\ In addition, the standards ``shall be
based on methods and technologies for removal or destruction of
pollutants'' before, during, and after combustion according to CAA
section 129(a)(3).\11\ The EPA has discretion to distinguish among
classes, types, and sizes of incinerator units within a category when
setting standards.\12\
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\9\ Id. 7429(a)(2).
\10\ Id. 7429(a)(4).
\11\ Id. 7429(a)(3).
\12\ Id. 7429(a)(2).
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In promulgating a MACT standard, the EPA must calculate the minimum
stringency levels for new and existing solid waste incineration units
in a category based on levels of emissions control achieved in practice
by the subject units. The minimum level of stringency is called the
MACT floor. Different approaches exist for determining the MACT floors
for new and existing sources. For new, modified, and reconstructed
sources, CAA section 129(a)(2) provides that the ``degree of reduction
in emissions that is deemed achievable . . . shall not be less
stringent than the emissions control that is achieved in practice by
the best controlled similar unit, as determined by the Administrator.''
\13\ Emissions standards for existing units may be less stringent than
standards for new units, provided that the standards ``shall not be
less stringent than the average emissions limitation achieved by the
best performing 12 percent of units in the category.'' \14\ The MACT
floors are the minimum standards that the EPA may consider for a source
category. As a part of the ``beyond-the-floor'' evaluation, however,
the EPA may consider standards more stringent than the MACT floor,
taking into account the costs, non-air quality health and environmental
impacts, and energy requirements of the more stringent controls.
---------------------------------------------------------------------------

\13\ Id.
\14\ Id.
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The MACT analysis involves assessing emissions from the best
performing units in a source category. The EPA can base this assessment
on actual emissions data and other information, such as State
regulatory requirements, that enable the EPA to estimate the
performance of the regulated units. For each source category, the
assessment involves a review of available emissions data and
information with an appropriate accounting for emissions variability.
The EPA can use other methods of estimating emissions, provided that
the methods can be shown to provide reasonable estimates of the actual
emissions performance of a source or sources in practice. Where there
is more than one method or technology to control emissions, the
analysis may result in several potential regulatory options, one of
which the EPA selects as the MACT for each pollutant. Each regulatory
option must be at least as stringent as the minimum-stringency floor
requirements. The EPA also examines, but is not required to adopt, more
stringent beyond-the-floor regulatory options to select the MACT. Based
on the EPA's consideration of the factors outlined in CAA section
129(a)(2), including the costs, any non-air quality health and
environmental impacts, and energy requirements, the EPA selects either
the MACT floor level of control or a beyond-the-floor level of control
as the MACT standard.
CAA section 129(a)(5) requires the EPA to review the NSPS and EG at
five-year intervals and, in accordance with CAA sections 129 and 111,
revise the NSPS and EG.\15\ CAA section 111 contains a similar periodic
``review and revise'' provision. Specifically, CAA section 111(b)(1)(B)
requires that the EPA, except in specified circumstances, review NSPS
promulgated under CAA section 111 every eight years and revise the
standards if the EPA determines that it is ``appropriate'' to do
so.\16\ In light of the explicit reference in CAA section 129(a)(5) to
CAA section 111, which directs the EPA to review and revise standards
previously promulgated only ``if appropriate,'' the EPA interprets CAA
section 129(a)(5) to likewise require that the EPA review and, if
appropriate, revise CAA section 129 standards.
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\15\ Id. 7429(a)(5).
\16\ Id. 7411(b)(1)(B).
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CAA section 129 provides guidance on the criteria relevant to
determining whether revising a CAA section 129 standard is
``appropriate.'' Specifically, CAA section 129(a)(3) states that
standards for solid waste incineration units under CAA sections 111 and
129 ``shall be based on methods and technologies for removal or
destruction of pollutants before, during and after combustion.'' \17\
This section's reference to methods and ``technologies'' supports the
inference that the EPA should consider advances in technology, both in
terms of effectiveness and costs, as well as the availability of new
technologies when determining whether revising a CAA section 129
standard is ``appropriate.'' This is the same general approach that the
EPA takes in periodically reviewing NSPS promulgated under CAA section
111(b)(1)(B).
---------------------------------------------------------------------------

\17\ Id. 7429(a)(3).
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CAA section 111(b)(1)(B) directs the EPA to ``review and, if
appropriate, revise [section 111 NSPS] following the procedure required
by this subsection for promulgation of such standards.'' \18\ Such
standards, as defined in section 111(a)(1), are based on ``the best
system of emission reduction'' or BSER, ``which (taking into account
the cost of achieving such reduction, and any non-air quality and
health and environmental impacts and energy requirements) the
Administrator determines has been adequately demonstrated.'' Because
the BSER is generally based on the degree of emission limitation
achievable by some type of control technology, in reviewing section 111
NSPS, the EPA evaluates advances in existing control technologies, both
in terms of performance and cost, as well as the availability of new
technologies. Based on this evaluation, the EPA then determines whether
it is appropriate to revise the standard. Similarly, in conducting CAA
section 129(a)(5) reviews, the EPA assesses the performance and
variability associated with control measures affecting emissions
performance at sources in the subject source category (including the
installed emissions control equipment), along with developments in
practices, processes and control technologies. In addition, associated
costs of control technologies are assessed to determine whether it is
appropriate to revise the NSPS and EG.
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\18\ Id. 7411(b)(1)(B).
---------------------------------------------------------------------------

The EPA does not interpret CAA section 129(a)(5), together with CAA
section 111, as requiring the Agency to recalculate MACT floors in
connection with this periodic review.\19\ CAA section 129(a)(5) does
not state that the EPA must conduct a MACT floor analysis every five
years when reviewing standards promulgated under CAA sections 129 and
111. Had Congress intended the EPA to conduct a new MACT floor analysis
every five years, Congress could have said so expressly, either by
directly incorporating such a requirement into CAA section 129(a)(5) or
by referring to CAA section 129(a)(2) specifically rather than broadly
to ``this section'' (i.e., CAA

[[Page 11806]]

section 129) \20\ and CAA section 111. Moreover, reading CAA section
129(a)(5) to require the EPA to recalculate MACT floors would be
inconsistent with Congress' direction that the EPA should revise CAA
section 129 standards in accordance with CAA section 111, which
provides that such revision should occur only if the EPA determines
that it is ``appropriate'' to do so. This approach would effectively
read the reference to CAA section 111 out of CAA section 129(a)(5).
Requiring the EPA to recalculate MACT floors would eviscerate the EPA's
ability to base revisions to CAA section 129 standards on a
determination that it is ``appropriate'' to revise such standards, as
the EPA's only discretion would be in deciding whether to establish a
standard that is more stringent than the recalculated floor. The EPA
believes that depriving the Agency of any meaningful discretion in this
manner is at odds with what Congress intended.
---------------------------------------------------------------------------

\19\ 71 FR 27324, 27327-28 (May 10, 2006); 73 FR 72962, 72971-72
(Dec. 1, 2008); 76 FR 15704, 15708 (Mar. 21, 2011); 85 FR 54178,
54182 (Aug. 31, 2020).
\20\ The scope of CAA section 129 further demonstrates why it
would be unreasonable to assume that Congress intended the EPA to
revise standards at five-year intervals based on a specific
standard-setting provision like CAA section 129(a)(2) as opposed to
a more general appropriateness standard. For example, CAA section
129(h)(3) separately requires the EPA to promulgate standards to
address residual risk (which, unlike MACT, is not a technology-based
analysis) if doing so would be required under CAA section 112(f). 42
U.S.C. 7412(h)(3). This review is required eight years after the
initial promulgation of CAA section 129 standards. Id. 7412(f)(2).
An interpretation of ``this section'' in CAA section 129(a)(5) that
incorporates the requirements of all standard-setting provisions in
CAA section 129, whether technology-based or risk-based or subject
to their own separate review schedule, would benonsensical.
---------------------------------------------------------------------------

The EPA believes that CAA section 129(a)(5) is best read as
conferring discretion to revise as ``appropriate'' taking into
consideration all relevant factors.\21\ The D.C. Circuit's ruling
regarding periodic review of hazardous air pollutant (HAP) standards
under CAA section 112(d)(6) supports this view.\22\ Like CAA section
129(a)(2), CAA section 112(d)(2) requires that the initial HAP
standards not be less stringent than the MACT floor, and CAA section
112(d)(6) requires that the EPA ``review, and revise as necessary'' the
HAP standards every eight years. The D.C. Circuit has repeatedly
rejected arguments that CAA section 112(d)(6) imposes a duty to
recalculate the MACT floor \23\ and held that the EPA may take into
account factors other than the ``non-exhaustive list of
considerations'' in section 112(d)(6) when deciding whether revision to
existing standards is ``necessary.'' \24\ The Court's rulings on
section 112(d)(6) are consistent with our interpretation of sections
129(a)(5) and 111 as providing the EPA discretion to revise, ``as
appropriate,'' MACT standards established under sections 129(a)(2) and
111.
---------------------------------------------------------------------------

\21\ See Michigan v. EPA, 576 U.S. 743, 752 (2015) (emphasizing
that `` `appropriate' is `the classic broad and all-encompassing
term that naturally and traditionally includes consideration of all
the relevant factors' '').
\22\ NRDC v. EPA, 529 F.3d 1077, 1084 (D.C. Cir. 2008).
\23\ Id.; see also Ass'n of Battery Recyclers v. EPA, 716 F.3d,
667, 673-74 (D.C. Cir. 2013); Nat'l Ass'n for Surface Finishing v.
EPA, 795 F.3d 1, 8, 11 (D.C. Cir. 2015).
\24\ La. Envtl. Action Network (LEAN) v. EPA, 955 F.3d 1088,
1097 (D.C. Cir. 2020).
---------------------------------------------------------------------------

For these reasons, the EPA does not recalculate the MACT floor in a
section 129(a)(5) review. Rather, as directed by section 129(a)(5), the
EPA follows the guidance in sections 111 and 129 and assesses advances
in existing control technologies, both in terms of performance and
cost, as well as the availability of new technologies, and then, on the
basis of this evaluation, the EPA determines whether it is appropriate
to revise the NSPS and EG.

B. What is the regulatory background for the large MWC source category,
and how do the NSPS and EG regulate emissions from the source category?

In December 1995, the EPA promulgated EG and NSPS for large MWC
units pursuant to CAA section 129.\25\ As stated in section II.A of
this preamble, these standards apply to large MWC units that have a
combustion capacity greater than 250 tpd of MSW.\26\ Both the EG and
NSPS require compliance with emission limitations that reflect the
maximum degree of emissions reductions for specific pollutants (Cd, CO,
PCDD/PCDF, HCl, Pb, Hg, NO<INF>X</INF>, PM, and SO<INF>2</INF>). The
1995 NSPS apply to new large MWC units that commenced construction,
were modified, or were reconstructed after September 20, 1994. The 1995
EG apply to existing large MWC units that commenced construction on or
before September 20, 1994. The 1995 EG required that owners or
operators of affected sources complete emission control retrofits by
December 2000. The EPA calculated the impact of floors based, in part,
on State issued air permits. These timely completed retrofits at
existing large MWC units were highly effective in reducing emissions of
most CAA section 129 pollutants from these units. Compared to a 1990
baseline of emissions, the 1995 EG reduced organic emissions (PCDD/
PCDF) by more than 99 percent, metal emissions (Cd, Pb, and Hg) by more
than 93 percent, and acid gas emissions (HCl and SO<INF>2</INF>) by
more than 91 percent.\27\ While the 1995 EG and NSPS also regulate
NO<INF>X</INF>, the emissions reductions for NO<INF>X</INF> were
relatively modest compared to those of the other CAA section 129
pollutants.\28\
---------------------------------------------------------------------------

\25\ 40 CFR part 60, subpart Cb (EG); 40 CFR part 60, subpart Eb
(NSPS).
\26\ In 1991, the EPA promulgated 40 CFR part 60, subpart Ea,
applying standards of performance to MWCs that commenced
construction after December 20, 1989, and on or before September 20,
1994. 56 FR 5507 (Feb. 11, 1991).
\27\ See memorandum entitled Emissions from Large MWC Units at
MACT Compliance, June 20, 2002. Walt Stevenson to Docket A-90-45,
entered as item A-90-45, VIII-B-11. Available online as Docket ID
EPA-HQ-OAR-2003-0072-0048.
\28\ Id.
---------------------------------------------------------------------------

In 2006, the EPA promulgated amendments to the 1995 standards after
completing a periodic review under CAA section 129(a)(5). The EPA
increased the stringency of the Cd and Hg NSPS emission limits based on
new compliance test data showing that large MWC units operating with a
full set of controls could comply with more stringent limits; similar
data were not available when the EPA previously set the NSPS emission
limits. The EPA also revised the PCDD/PCDF, Hg, and NO<INF>X</INF> EG
emission limits and compliance testing provisions to more accurately
reflect the actual performance achieved by existing MWCs and their
control technologies and to reflect improvements in continuous
emissions monitoring system (CEMS) data performance and reliability
based on large MWC compliance test data.\29\ The EPA projected that all
large MWCs could meet the 2006 EG emission limits without installing
any new control technology.\30\
---------------------------------------------------------------------------

\29\ 71 FR 27324 (May 10, 2006).
\30\ Id.
---------------------------------------------------------------------------

Following promulgation of the 2006 final rule, environmental groups
challenged the MACT floor limits that the EPA promulgated in 1995 in
connection with their challenge to the revised standards, citing a
then-recent decision questioning the legality of MACT floors derived in
part from State-issued air permits.\31\ In light of this decision and
several other relevant decisions regarding the calculation of MACT
floors under CAA section 112, the EPA sought a voluntary remand of the
2006 final rule.\32\ In its remand

[[Page 11807]]

motion, the EPA announced its intention to grant the environmental
groups' administrative petition to revisit the 1995 MACT floors and
reevaluate the 2006 final rule as necessary to comport with any
revisions.\33\ The D.C. Circuit granted the EPA's request for a remand
in February 2008.\34\
---------------------------------------------------------------------------

\31\ Specifically, petitioners pointed to a 2004 decision from
the D.C. Circuit, which remanded MACT floors established for
existing small MWCs derived from state-issued permit limits after
finding that the EPA did not fulfill the requirement of CAA section
129(a)(2). See Ne. Md. Waste Disposal Auth. v. EPA, 358 F.3d 936
(D.C. Cir. 2004).
\32\ See Sierra Club v. EPA, 479 F.3d 875 (D.C. Cir. 2007)
(vacating the EPA's regulations setting national emission standards
for brick and clay ceramics kilns under CAA section 112); NRDC v.
EPA, 489 F.3d 1250 (D.C. Cir. 2007) (vacating the EPA's regulations
setting national emission standards under CAA section 112 for
hazardous air pollutants from industrial, commercial, and
institutional boilers and process heaters and the EPA's regulations
under CAA section 129 defining the term ``commercial and industrial
solid waste incineration unit''); NRDC v. EPA, 489 F.3d 1364 (D.C.
Cir. 2007) (vacating portions of an EPA rule promulgated under CAA
section 112 regulating hazardous air pollutants from the manufacture
of plywood and composite wood products).
\33\ In its motion for a voluntary remand, the EPA explained
that it intended to ``re-analyze the floors in the 1995 rule'' and
``revisit the data and information used in the 1995 rule, as well as
obtain additional data, to determine whether the 1995 floors need to
be revised.'' EPA Motion for Voluntary Remand at 8, Sierra Club v.
EPA, No. 06-1250 (D.C. Cir. filed Nov. 9, 2007).
\34\ Order, Sierra Club v. EPA, No. 06-1250 (D.C. Cir. filed
Feb. 15, 2008).
---------------------------------------------------------------------------

In December 2021, another environmental group petitioned in the
D.C. Circuit for a writ of mandamus related to the 2008 order granting
voluntary remand.\35\ In January 2022, the same organization also filed
a citizen suit under CAA section 304(a)(2), alleging that the EPA
failed to carry out a nondiscretionary duty to timely review and, if
appropriate, revise emissions standards for large MWCs pursuant to the
five-year review provision in CAA section 129(a)(5).\36\ On November 9,
2023, the D.C. Circuit entered a consent decree requiring the EPA to
sign a proposed rule by December 31, 2023, and a final rule by November
30, 2024, to satisfy the EPA's obligations in the citizen suit and
mandamus action (i.e., to complete the five-year review and MACT floor
reevaluation). The parties later filed a joint stipulation to extend
the consent decree deadline for the final rule to December 22,
2025.\37\
---------------------------------------------------------------------------

\35\ In re E. Yard Cmtys. for Envtl. Justice, No. 21-1271 (D.C.
Cir. filed Dec. 21, 2021).
\36\ E. Yard Cmtys. for Envtl. Justice v. EPA, No. 22-cv-0094
(D.C. Cir. filed Jan. 13, 2022).
\37\ Notice of Lodging of Proposed Consent Decree, E. Yard Cmty.
for Envtl. Justice v. EPA, No. 22-cv-0094 (D.C. Cir., filed May 23,
2023).
---------------------------------------------------------------------------

C. What changes did we propose for the large MWC source category?

On January 23, 2024, the EPA proposed revisions to the NSPS and EG
for large MWCs to reflect the results of the EPA's reevaluation of the
MACT floors, pursuant to the 2008 voluntary remand, and the results of
the EPA's five-year review, pursuant to CAA section 129(a)(5).\38\ The
EPA proposed the following with respect to 40 CFR part 60, subparts Cb
and Eb:
---------------------------------------------------------------------------

\38\ 89 FR 4243 (Jan. 23, 2024).
---------------------------------------------------------------------------

<bullet> Revisions to all existing-source emission limits in the
EG, except the existing CO and NO<INF>X</INF> limits for two
subcategories of combustors, and revisions to all new-source emission
limits in the NSPS. With the exception of proposed changes to the
NO<INF>X</INF> limits, the proposed revisions resulted from the EPA's
reevaluation of the MACT floors in response to the 2008 voluntary
remand.
<bullet> Simultaneously, the EPA conducted a five-year review as
required by CAA section 129(a)(5). Based on this review, the EPA
proposed NO<INF>X</INF> standards that were more stringent than the
reevaluated MACT floor emissions limits for NO<INF>X</INF> and that
were consistent with the recently promulgated Good Neighbor Plan, which
set ozone season standards for a significant portion of the large MWC
source category.\39\
---------------------------------------------------------------------------

\39\ 88 FR 36654 (June 5, 2023).
---------------------------------------------------------------------------

<bullet> Removal of the alternative percent reduction standards to
establish a consistent approach to compliance for all facilities and
removal of the NO<INF>X</INF> emissions averaging allowance for
existing sources.
<bullet> Removal of the SSM exclusions and exemptions and
significant revisions to the monitoring provisions during these
periods. For NO<INF>X</INF>, SO<INF>2</INF>, and CO, where a CEMS
continuously measures the pollutant concentration, we proposed to
eliminate the exclusions of periods of SSM from CEMS data averaging
calculations present in the 1995 large MWC standards and instead
require a monitoring and compliance demonstration approach used in the
more recent CAA section 129 rulemaking for commercial and industrial
solid waste units (CISWI) NSPS and EG.\40\
---------------------------------------------------------------------------

\40\ 81 FR 40956 (June 23, 2016).
---------------------------------------------------------------------------

<bullet> Conversion of the 1995 large MWC regulatory text
describing emission standards and performance testing requirements from
paragraphs into tables to facilitate easier implementation and
understanding of the requirements.
<bullet> Requiring source owners and operators to submit electronic
copies of required performance test reports, performance evaluation
reports, semiannual compliance reports, and annual reports through the
EPA's Central Data Exchange (CDX), using the Compliance and Emissions
Data Reporting Interface (CEDRI), to increase the usefulness of the
data contained in those reports and to improve availability and
transparency of data.
<bullet> Reestablishing new and existing source applicability so
that large MWC units currently subject to the 2006 NSPS would become
``existing'' sources under the proposed amended standards and would be
required to meet the revised EG by the applicable compliance date for
the revised guidelines. Large MWC units that commence construction
after the date of the proposal or commence a modification on or after
the date six months after promulgation of the amended standards would
be ``new'' units subject to the more stringent NSPS emission limits.
<bullet> Eliminating the regulatory title V permitting requirement
for air curtain incinerators that burn only wood waste, yard waste, and
clean lumber and are not located at a major source or subject to title
V for other reasons.
<bullet> Other technical amendments, including closing a 2007
proposed reconsideration action, correcting certain typographical
errors, making certain technical corrections, and clarifying certain
provisions in the NSPS and EG.\41\
---------------------------------------------------------------------------

\41\ 72 FR 13016 (Mar. 20, 2007).
---------------------------------------------------------------------------

D. What outreach did we conduct following the proposal?

In developing this final rule, the EPA conducted post-proposal
outreach activities with communities, States, local governments,
industry, and Tribes. On January 11, 2024, the EPA emailed a
consultation letter to Tribal nations explaining how to comment on the
proposed rulemaking and how to request consultation with the EPA. The
EPA participated in the National Tribal Air Association monthly meeting
on January 25, 2024. On January 16, 2024, the EPA presented details of
the large MWC proposal to members of interested communities and
environmental organizations. Additionally, the EPA held an
informational webinar with air pollution control agencies on February
29, 2024. The EPA's outreach activities also included meetings with the
following: Waste-to-Energy Association (WTEA) to discuss varying
aspects of the proposal, including waste variability, Reworld Waste
(formerly Covanta) to discuss their concerns about the proposed
emission limits, compliance implications, and costs of the proposal,
and a coalition of community representatives and organizations to
discuss their concerns about the rulemaking and impacts of air
pollution near large industrial facilities. The EPA subsequently
reopened the comment period on the proposed amendments to the large MWC
regulations for an additional 4 months, from January 16, 2025, to May
30, 2025,

[[Page 11808]]

to gather additional information and documentation.

III. What is included in these final rules?

In this action, we are finalizing decisions and revisions for the
NSPS and EG for large MWC units. We discuss the significant comments on
the proposal and changes the EPA made to the final NSPS and EG in more
detail in section IV of this preamble. A comment summary and the EPA's
responses are available in the docket.\42\
---------------------------------------------------------------------------

\42\ Summary of Public Comments and Responses for Standards of
Performance for New Stationary Sources and Emission Guidelines for
Existing Sources: Large Municipal Waste Combustors Voluntary Remand
Response and 5-year Review (``Comment Response Document''), Docket
ID No. EPA-HQ-OAR-2017-0183.
---------------------------------------------------------------------------

This final rule sets out the EPA's determinations resulting from
our reevaluation of the 1995 MACT floor standards for large MWCs
pursuant to the 2008 voluntary remand and from our five-year review of
large MWC standards under CAA section 129(a)(5), as well as the final
amendments to the large MWC NSPS and EG based on those determinations.
This action also finalizes other changes to the NSPS and EG largely as
proposed, including the following: removal of SSM exclusions and
exemptions; streamlined regulatory language; revisions to recordkeeping
and reporting requirements; addition of electronic reporting
requirements; reestablishment of new and existing source applicability
dates; elimination of title V requirements for air curtain incinerators
that burn only wood waste, yard waste, and clean lumber and are not
located at a major source or subject to title V for other reasons;
closing the 2007 proposed reconsideration action; and other technical,
typographical, and clarifying corrections to certain provisions in the
NSPS and EG.
The EPA is finalizing the amendments as new subparts VVVV
(Standards of Performance for Large Municipal Waste Combustors) and
WWWW (Emissions Guidelines and Compliance Times for Large Municipal
Waste Combustors That are Constructed on or Before January 23, 2024),
in lieu of revising existing subparts Cb (Emissions Guidelines and
Compliance Times for Large Municipal Waste Combustors That are
Constructed on or Before September 20, 1994) and Eb (Standards of
Performance for Large Municipal Waste Combustors for Which Construction
is Commenced After September 20, 1994 or for Which Modification or
Reconstruction is Commenced After June 19, 1996). As proposed, we are
reserving (removing without replacing) subpart Ea (NSPS limits for
units constructed after December 20, 1989, and on or before September
20, 1994). Although we proposed to promulgate amendments as revisions
to subparts Cb and Eb, the EPA has determined that creating new
subparts will lessen confusion for affected sources and implementing
agencies. Therefore, we have created new subparts for the NSPS and EG
at 40 CFR part 60, subparts VVVV and WWWW, respectively, which will
replace subparts Cb, Ea, and Eb once facilities are required to comply
with the new subparts. The revised standards and new subparts will
become effective May 11, 2026. For the EG, States must submit revised
State plans to the EPA within one year after promulgating the
amendments, by March 10, 2027. Existing large MWC units must
demonstrate compliance with the updated standards as expeditiously as
practicable after approval of a State plan, but no later than three
years after the date of approval of a State plan or five years after
promulgation of the revised standards, whichever is earlier. For NSPS,
new sources must be in compliance with the updated standards within six
months from promulgation, by September 10, 2026, or upon startup,
whichever is later.
By incorporating these amendments as new subparts, we hope to
alleviate confusion that may arise from significant amendments to the
current subpart Cb and subpart Eb regulatory text. For example, to
support making the format and structure of the regulations more
understandable based on Federal Plain Language Guidelines, we are
moving the requirements in subparts Cb and Eb to subparts VVVV and
WWWW. Additionally, by creating new subparts VVVV and WWWW, we can omit
transitional regulatory requirement language and have a single
applicability date (i.e., January 23, 2024) for the new subparts, upon
which applicability of subparts Cb, Ea, and Eb ends and a single
subpart, WWWW, apply to all the current, operating large MWCs. (We
provide additional information on the effective and compliance dates of
the final rule in section III.D of this preamble.) Finally, to better
accommodate potential future updates to the regulations, in subparts
VVVV and WWWW, we are numbering sections in increments of five to
support adequate numeric spacing to revise or add new regulatory text
sections if needed.

A. What are the final rule amendments based on the response to the
voluntary MACT floor remand and five-year review for the large MWC
source category?

1. Emission Limits
In the proposed rule, the EPA presented amendments resulting from
its reevaluation of the 1995 large MWCs MACT standards undertaken
pursuant to the D.C. Circuit's 2008 voluntary remand and the EPA's
five-year review of large MWC standards, undertaken pursuant to CAA
section 129(a)(5). Based on the EPA's reevaluation of the MACT floors
and beyond-the-floor options and review of the standards and
requirements, the EPA proposed revised limits at the MACT floor for all
covered pollutants except for NO<INF>X</INF>, for which the EPA
proposed to implement more stringent emission standards as a result of
the five-year review.
Following consideration of comments, input from stakeholder
meetings, and additional data received post-proposal, the EPA revised
its initial reevaluation of the 1995 MACT floors and is finalizing
recalculated emission limits.\43\ Specifically, for the EG, the EPA is
finalizing newly revised emission limits for all pollutants, except for
the CO and NO<INF>X</INF> limits for two categories and subcategories
of combustors, respectively. The revised limits reflect the MACT floor
reevaluation results rather than the results of the five-year review.
For the NSPS, the EPA is finalizing revised reevaluated MACT emission
limits for all pollutants except NO<INF>X</INF>, which will retain the
proposed five-year review limit for new sources.\44\
---------------------------------------------------------------------------

\43\ As explained in sections IV.A.3 and IV.A.4 of this
preamble, the EPA received additional emissions test data from the
1990-1995 period during the original comment period and the
supplemental 2025 comment period that bolstered the dataset
available for reanalysis of the MACT floors.
\44\ See section IV of this preamble for rationale for these
revisions and summarized comments and responses on this topic.
---------------------------------------------------------------------------

Tables 2 and 3 of this preamble present the final EG and NSPS
emission limits for large MWCs, respectively. For comparison, the table
presents current emission limits (from the 2006 rule) for both existing
and new units as well. The EPA assessed NO<INF>X</INF> and CO limits by
subcategories, determined based on combustor type, including mass burn
waterwall (MB/WW), mass burn rotary combustor (MB/RC), refuse-derived
fuel stoker (RDF/S), RDF spreader stoker fixed floor/100 percent coal
capable and RDF semi-suspension/wet RDF process

[[Page 11809]]

conversion (RDF/SS), and RDF/fluidized bed combustion (RDF/FBC).\45\
---------------------------------------------------------------------------

\45\ The EG contain CO emission limits for two additional
subcategories of units that are not found in the NSPS. More recent
installations have not used these designs, and the EPA expects that
most new large MWCs will likely be MB/WW.

Table 2--Comparison of Existing Source Limits for 2006 Large MWC Rule and the Final Emission Limits for Existing Sources
--------------------------------------------------------------------------------------------------------------------------------------------------------
2006 EG Final subcategory EG limits
Pollutant Units (@7 percent O2) (current) ----------------------------------------------------------------
limits MB/WW MB/RC RDF/S RDF/SS RDF/FBC
--------------------------------------------------------------------------------------------------------------------------------------------------------
Cd......................................... [mu]g/dscm................... 35 10
Pb......................................... [mu]g/dscm................... 400 68
PM......................................... mg/dscm...................... 25 20
Hg......................................... [mu]g/dscm................... 50 50
PCDD/PCDF.................................. ng/dscm (total mass basis)... \1\ 30/35 14
HCl........................................ ppmvd........................ 29 10
SO2........................................ ppmvd........................ 29 22
----------------------------------------------------------------
NOX........................................ ppmvd........................ \2\ 180-250 \4\ 205 150 160 160 \4\ 180
CO......................................... ppmvd........................ \3\ 50-250 \4\ 100 110 110 \4\ 250 110
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ 30 ng/dscm for fabric filter equipped MWC units and 35 ng/dscm for electrostatic precipitator-equipped MWC units.
\2\ Range in limits based on combustor type. MB/WW (205); RDF (250); MB/RC (210); RDF/FBC (180).
\3\ Range in limits based on combustor type. MB/WW (100); MB/RC (250); RDF/S (200); RDF/SS (250); RDF/FBC (200); modular starved air or modular excess
air (50).
\4\ Reevaluated MACT floor limit was less stringent than current limit, so current limit was retained.

Table 3--Comparison of New Source Limits for 2006 Large MWC Rule and the Final Emission Limits for New Sources
----------------------------------------------------------------------------------------------------------------
2006 NSPS Final subcategory NSPS limits
Pollutant Units (@7 percent O2) (current) -------------------------------
limits MB RDF
----------------------------------------------------------------------------------------------------------------
Cd.................................... [mu]g/dscm.............. 10 2.3
Pb.................................... [mu]g/dscm.............. 140 23
PM.................................... mg/dscm................. 20 5.1
Hg.................................... [mu]g/dscm.............. 50 32
PCDD/PCDF............................. ng/dscm (total mass 13 11
basis).
HCl................................... ppmvd................... 25 7.2
SO2................................... ppmvd................... 30 14
NOX \1\............................... ppmvd................... 150 50
-------------------------------
CO.................................... ppmvd................... \2\ 50-150 76 100
----------------------------------------------------------------------------------------------------------------
\1\ NOX limit based on 50 ppm (24 hour) permitted limit for units currently equipped with selective catalytic
reduction (SCR) control devices.
\2\ Range in limits based on combustor type. MB/WW (100); RDF/S (150); Modular starved air or modular excess air
(50).

2. MACT Floor Assessment
This final rule fulfills the EPA's reevaluation of the 1995 MACT
floors for the large MWC source category pursuant the D.C. Circuit's
2008 voluntary remand of the 2006 large MWC rule, as discussed in
section II.B of this preamble. In response to the remand, the EPA
explained at proposal that the Agency lacked sufficient data from the
time period of the 1995 large MWC rulemaking to now characterize the
performance of all units needed to reassess the original MACT floors.
The EPA proposed to recalculate the MACT floors for large MWCs based on
compliance data from 2000 through 2009 reported for the population of
units that were operating at the time of the original EG development
(1990), adjusted to account for the installation of air pollution
control devices (APCD) and other improvements that sources made to meet
the 1995 standards. The EPA subsequently ranked the best performing
units in the source category for each covered pollutant based on the
adjusted emissions, analyzed the data to determine the average
performance of those units, considered beyond-the-floor options, and
established MACT floor emission limits.\46\
---------------------------------------------------------------------------

\46\ See discussion in section III.A.3 of this preamble.
---------------------------------------------------------------------------

Following consideration of comments and additional information
received on the proposed rule, the EPA is revising its reassessment of
the MACT floor limits for the EG and NSPS. The EPA is finalizing a
similar approach as that in the proposed rule, using separate
methodologies for pollutants having stack test data (Cd, Pb, Hg, PM,
HCl, and PCDD/PCDF) and pollutants having CEMS data (or CEMS
pollutants) (CO, NO<INF>X</INF>, and SO<INF>2</INF>). However, the
final limits incorporate new data submitted for years 1990 to 1995 for
unit ranking and UPL determinations, in addition to the 2000 to 2009
compliance dataset that the EPA used for the proposed limits.
Considering the unique situation of the MACT reevaluation, the EPA's
limited ability to gather multiple years of tests for the top
performers from several decades ago, and the high variability of waste
that these sources use as fuel, the EPA also has revised the NSPS
methodology to account for additional intra-source variability in top
performers, instead of relying on a singular test from the 1990s. For
each stack test pollutant, the EPA performed a statistical analysis on
the annual test averages from the 1990 to 1995 dataset

[[Page 11810]]

and adjusted averages from the 2000 to 2009 dataset to determine an
upper prediction limit (UPL).\47\ For EG limits, the EPA used average
annual run data corresponding to the top 12 percent of units, and for
NSPS limits, the EPA used run data for the single top performer. For
NSPS limits, the EPA also assessed the distribution and variance of
2000 to 2009 test averages for the top performer incorporated this data
into the UPL calculation.
---------------------------------------------------------------------------

\47\ For a more detailed discussion, see section IV.A.4 of this
preamble.
---------------------------------------------------------------------------

For CEMS pollutants (CO, NO<INF>X</INF>, and SO<INF>2</INF>), the
EPA reevaluated MACT floor limits by averaging annual peak CEMS data
corresponding to the top performers for each pollutant and applicable
subcategory. For NO<INF>X</INF> and CO, the EPA calculated separate
NSPS limits for only two subcategories, MB (as reflected by MB/WW
combustor technology) and RDF. In cases where results were greater
(less stringent) than the current large MWC EG limit, the EPA proposed
to retain the existing regulatory limit as the MACT floor limit. While
the methodology has not changed from proposal, based on comments and
evaluation of the data from the units identified as best performers for
CO at proposal, we performed a paired t-test analysis on the best
performers for CO and determined that the data reported for
Wheelabrator Bridgeport Units #1, #2, and #3 exhibit a different
population characteristic from the remainder of the source category,
i.e., statistically, there is a significant difference in the CO data
reported by the Wheelabrator Bridgeport facility from the CO data
reported by all other facilities that is outside the variation we would
expect of CO emissions from large MWCs. This indicates that the owner
or operator of these units may have reported the data in a different
way than requested based on a different understanding of the reporting
requirement, resulting in reported CO numbers that were much lower than
all other facilities not because of better operation and lower
emissions but because of differently understood reporting requirements.
As a result, the EPA removed the CEMS data for these units from the
CEMS pollutant calculations. The removal results in a new NSPS CO limit
of 76 ppmvd from the proposed NSPS CO limit of 16 ppmvd and an EG
SO<INF>2</INF> limit of 22 ppmvd from the proposed EG SO<INF>2</INF>
limit of 20 ppmvd. Further discussion of this change from proposal is
in section IV of this preamble.
Table 4 of this preamble presents the UPL results and the derived
final EG and NSPS MACT floor limits for stack test pollutants. Tables 5
and 6 of this preamble summarize the averages and subsequent MACT floor
EG and NSPS limits, respectively, for CEMS pollutants. Additional
discussion of the methodology, detailed results, and a copy of the UPL
template are available in the docket for this rulemaking.\48\
---------------------------------------------------------------------------

\48\ See memorandum entitled MACT Floor Calculations for Large
Municipal Waste Combustor Units--Final Rule, Docket ID No. EPA-HQ-
OAR-2017-0183.

Table 4--Large MWC MACT Floor EG and NSPS Limits for Stack Test Pollutants
----------------------------------------------------------------------------------------------------------------
EG MACT floor calculations NSPS MACT floor calculations
Units (@7 ----------------------------------------------------------------
Pollutant percent O2) MACT floor MACT floor
UPL result limit UPL result limit
----------------------------------------------------------------------------------------------------------------
Cd........................... [mu]g/dscm...... 9.99 10 0.577 \1\ 2.3
Pb........................... [mu]g/dscm...... 67.86 68 5.33 \1\ 23
PM........................... mg/dscm......... 19.05 20 5.06 5.1
Hg........................... [mu]g/dscm...... 52.67 50 31.60 32
PCDD/PCDF.................... ng/dscm......... 13.88 14 10.61 11
HCl.......................... Ppmvd........... 9.82 10 7.103 7.2
----------------------------------------------------------------------------------------------------------------
\1\ Calculated UPL result was less than three times the representative detection level (RDL), so MACT Floor
limit set at the 2 dscm 3*RDL value (2.3 ug/dscm for Cd, 23 ug/dscm for Pb).

Table 5--Large MWC MACT Floor EG Limits for CEMS Pollutants
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
EG MACT floor calculations
-------------------------------------------------------------------------------------------------------------
Pollutant Units (@7 percent O2) Average of annual peak CEMS data MACT floor limit
-------------------------------------------------------------------------------------------------------------
MB/WW MB/RC RDF RDF/SS RDF/FBC MB/WW MB/RC RDF RDF/SS RDF/FBC
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
SO2............................................ ppmvd............................ 21.26
22
-------------------------------------------------------------------------------------------------------------
NOX............................................ ppmvd............................ 226.52 142.25 157.29 290.83 \a\ 205 150 160 \1\ 180
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
CO............................................. ppmvd............................ 221.44 109.92 102.14 818.90 101.40 \a\ 100 110 110 \1\ 250 110
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Calculated limit was less stringent than current limit so kept at current limit.

Table 6--Large MWC MACT Floor NSPS Limits for CEMS Pollutants
----------------------------------------------------------------------------------------------------------------
NSPS MACT floor calculations
---------------------------------------------------------------
Units (@7 Average of annual peak CEMS MACT floor limit
Pollutant percent O2) data -------------------------------
--------------------------------
\1\ MB \1\ RDF \1\ MB \1\ RDF
----------------------------------------------------------------------------------------------------------------
SO2........................... ppmvd........... 13.96
14
---------------------------------------------------------------
NOX........................... ppmvd........... 130.50 154.46 \2\ 140 \2\ \3\ 150
CO............................ ppmvd........... 75.71 99.03 76 100
----------------------------------------------------------------------------------------------------------------
\1\ The MB/RC, RDF/SS, and RDF/FBC subcategories are representative of unique facilities that likely will not be
a design used in any future large MWC units. For the NSPS purposes, it is assumed the overarching MB or RDF
subcategories will represent performance of any units built in the future.

[[Page 11811]]

\2\ These values represent limits that would have resulted if the EPA had selected the MACT floor as its basis
for the NSPS NOX limits; however, the EPA is finalizing the proposed 50 ppmvd NOX limit for all subcategories
based on units currently equipped with SCR control devices.
\3\ Calculated limit was less stringent than current limit, so current limit would have been retained if the
MACT floor were selected.

3. Beyond-the-Floor and Five-Year Review Results and Selection of
Emission Limits
Following consideration of comments received on the proposed rule,
the EPA is not finalizing the beyond-the-floor and five-year review
assessments for the EG as proposed. The final rule uses the MACT floor
calculations to establish EG and NSPS limits for existing and new units
for all pollutants except for NO<INF>X</INF> (which reflect the results
of the MACT floor calculations for the EG as well as the results of the
five-year review for the NSPS).
For its proposed assessment of beyond-the-floor in the reevaluation
of the 1995 standards, the EPA assumed that the beyond-the-floor option
for existing sources is the new source MACT floor (emissions control
achieved in practice by the best controlled similar unit, as required
by CAA section 129(a)(2)) which is more stringent than the existing
source MACT floor (an average of a broader range of best performing
units, also as required by CAA section 129(a)(2)). To assess
additional, currently in-use control options as part of the five-year
review pursuant to CAA section 129(a)(5), the EPA evaluated the
performance of control measures at large MWC sources (including the
installed emissions control equipment), and recent developments in
practices, processes, and control technologies, including the recently
finalized Good Neighbor Plan rulemaking. The EPA proposed
NO<INF>X</INF> control technologies consistent with those discussed in
the Good Neighbor Plan as five-year review options for consideration.
For the other covered pollutants, there are some controls that have
been demonstrated on non-MWC combustion sources that could potentially
be applied to large MWCs; however, the technical feasibility and cost-
effectiveness of these controls when used on large MWCs are highly
uncertain at this time.
Following its evaluation of these scenarios, the EPA proposed a 110
ppmvd (24-hour) NO<INF>X</INF> limit (which was consistent with the
NO<INF>X</INF> limit finalized under the Good Neighbor Plan), as the
five-year review option for existing units based on the application of
advanced selective noncatalytic reduction (ASNCR) or Covanta
LNTM NO<INF>X</INF> technologies. The EPA also proposed a
NO<INF>X</INF> NSPS limit of 50 ppmvd (24-hour), based on the permitted
NO<INF>X</INF> limit for the only facility currently using selective
catalytic reduction (SCR) technology with an air-to-air heat exchanger
providing flue gas reheat prior to entering the SCR reactor to
represent the five-year technology review standard for new sources.
Based on the consideration of several factors, including the stay
of the Good Neighbor Plan,\49\ the EPA is not finalizing the five-year
review limit for NO<INF>X</INF> emissions from existing units as
proposed. First, the total compliance costs for existing sources to
meet the proposed 110 ppmvd NO<INF>X</INF> limit is significantly
higher than the EPA's estimate in the proposed rule. At proposal, the
EPA excluded units expected to be covered by the Good Neighbor Plan
from the $257 million capital cost estimate. Inclusion of the
compliance costs for those units significantly increases the total
estimated capital cost to $412 million. These large capital
expenditures likely will pose a significant challenge to the large MWC
industry. The EPA recognizes that this is a unique industry providing
essential public services, with many facilities owned and operated by
State or local governments. These large capital expenditures could
hinder government funded municipalities' ability to continue to utilize
large MWCs for the public MSW disposal needs.
---------------------------------------------------------------------------

\49\ See Ohio v. EPA, 603 U.S. 279 (2024) (staying the Good
Neighbor Plan as likely arbitrary and capricious).
---------------------------------------------------------------------------

Second, at the same time, emission reductions from the proposed 110
ppmvd NO<INF>X</INF> limit likely are much lower than the EPA's
estimate at proposal. The EPA estimated baseline NO<INF>X</INF>
emissions using the average of the available annual peak 24-hour CEMs
data from 2000 through 2007. Using the peak values likely overestimates
annual emissions by about 30% compared to the 2008 National Emissions
Inventory and, in turn, likely overestimates the amount of emission
reductions and therefore the cost effectiveness of the proposed
NO<INF>X</INF> limit.\50\
---------------------------------------------------------------------------

\50\ 2008 National Emissions Inventory (<a href="https://www.epa.gov/air-emissions-inventories/2008-national-emissions-inventory-nei-data">https://www.epa.gov/air-emissions-inventories/2008-national-emissions-inventory-nei-data</a>).
---------------------------------------------------------------------------

For these reasons, the EPA is not finalizing the 110 ppmvd limit
for NO<INF>X</INF> for existing sources and is instead promulgating the
re-evaluated MACT floor limits for existing sources discussed in
section III.A.2 of this preamble. The EPA is finalizing the 50 ppmvd
NO<INF>X</INF> limit for new sources as proposed, as there are units
operating that have cost-effectively used SCR to perform at this level
for several years, and the EPA sees no technical or economic barriers
to future sources doing likewise.

B. What are the final rule amendments addressing emissions during
periods of startup, shutdown, and malfunction?

The EPA is finalizing, as proposed, revisions to the SSM provisions
of the NSPS and EG in response to the D.C. Circuit's decision in Sierra
Club v. EPA.\51\ This final rule removes the exemption for SSM periods
contained in the 1995 large MWC rule so that the emission standards
apply at all times. The EPA is not finalizing a separate emission
standard for large MWC units during periods of startup and
shutdown.\52\
---------------------------------------------------------------------------

\51\ 551 F.3d 1019 (D.C. Cir. 2008).
\52\ See the rationale in section IV.B of this preamble.
---------------------------------------------------------------------------

The EPA notes that on September 5, 2025, the D.C. Circuit held in
SSM Litigation Group v. EPA that although the EPA has no authority
under the CAA to ``create a regulatory `defense' that limits the
remedial authority granted by Congress to the Federal courts,'' a
``complete affirmative defense, like the one at issue [in that case],
is permissible because it relates to the antecedent question of
liability and therefore does not impinge on the judiciary's authority
to award `appropriate civil penalties.' '' \53\ The EPA is not
addressing SSM litigation Group in this action because the LMWC NSPS
and EG do not contain affirmative defense provisions. However, the EPA
may in an appropriate future action request comment on whether and how
we should establish affirmative defense provisions within section 129
regulations in response to the D.C. Circuit's SSM Litigation Group
decision. As proposed, the emission standards that the EPA is
finalizing do not factor emissions that occur during periods of
malfunction into the development of the standards. This is consistent
with the D.C. Circuit's decision in U.S. Sugar Corp. v.
EPA,54 as explained further below.
---------------------------------------------------------------------------

\53\ 150 F.4th 593, 599 (D.C. Cir. 2025) (quoting CAA section
304(a), 42 U.S.C. 7604(a)).
\54\ 830 F.3d 579, 606-10 (D.C. Cir. 2016).
---------------------------------------------------------------------------

The EPA is also finalizing, as proposed, revisions to eliminate the
exclusions of periods of warmup, startup, and shutdown from CEMS data
averaging calculations and to replace

[[Page 11812]]

them with a monitoring and compliance demonstration approach. The final
rule requires that affected sources collect CEMS data and use this data
to determine compliance when the large MWC unit is operating. While the
large MWC unit is warming up, starting up, or shutting down, CEMS data
must be flagged as warmup, startup, or shutdown period data. The final
rule requires that affected sources use the CEMS data to calculate
rolling or block averages and to average the data as measured instead
of applying a seven percent oxygen diluent cap for the warmup period
and an allowance of up to three hours of startup or shutdown time per
occurrence. Under the final rule, a deviation occurs when an operating
combustor does not record monitoring data due to monitor malfunctions.

C. What are the final rule amendments addressing other changes to the
large MWC EG and NSPS?

1. Changes to the Applicability Date of the Large MWC EG and NSPS
As noted earlier in section III of this preamble, the EPA is
finalizing the amendments as 40 CFR part 60, subparts VVVV (Standards
of Performance for Large Municipal Waste Combustors) and WWWW
(Emissions Guidelines and Compliance Times for Large Municipal Waste
Combustors That are Constructed on or Before January 23, 2024), in lieu
of revising existing subparts Cb (Emissions Guidelines and Compliance
Times for Large Municipal Waste Combustors That are Constructed on or
Before September 20, 1994) and Eb (Standards of Performance for Large
Municipal Waste Combustors for Which Construction is Commenced After
September 20, 1994 or for Which Modification or Reconstruction is
Commenced After June 19, 1996).
The EPA is finalizing, as proposed, that large MWC units currently
subject to the NSPS are existing sources with respect to the emission
standards promulgated in this final rule. Under this final rule, large
MWC units that currently are subject to the NSPS at 40 CFR part 60,
subparts Ea and Eb will be subject to the revised EG standards at 40
CFR part 60, subpart WWWW through meeting requirements of the relevant
approved State or Federal plans. Those sources will continue to be NSPS
units subject to the current large MWC NSPS until the sources come into
compliance with the requirements of the revised EG standards. The
revised EG standards are as stringent as, or more protective than, the
1995 large MWC new source emission limits, as revised in 2006, with the
sole exception of PCDD/PCDF. For the PCDD/PCDF limit, large MWC units
that are subject to NSPS subpart Eb but are existing sources under the
new EG subpart WWWW remain new sources under NSPS subpart Eb and, as
such, must continue to comply with the more stringent NSPS limit (i.e.,
13 ng/dscm total mass basis at seven percent oxygen) in NSPS subpart
Eb.
Under the final rule, large MWC units that commence construction
after January 23, 2024, and units that are modified or reconstructed
after September 10, 2026 are new units subject to the NSPS emission
limits. Large MWC units that commence construction, reconstruction, or
modification prior to those dates would be existing units subject to
the revised EG standards under 40 CFR part 60, subpart WWWW. Under the
final rule, any large MWC unit that commenced construction on or before
January 23, 2024, or that is reconstructed or modified prior to
September 10, 2026, remains subject to 40 CFR part 60 subparts Cb, Ea,
or Eb, as appropriate, until the unit comes into compliance with the
relevant approved State or Federal plan to implement and enforce the
revised EG. Large MWC units that commence construction after January
23, 2024, or that are reconstructed or modified on or after September
10, 2026 must meet the revised NSPS emission limits in 40 CFR part 60,
subpart VVVV by September 10, 2026, or upon startup, whichever is
later.
As stated in the proposal, the EPA intends to ``reserve'' 40 CFR
part 60, subpart Ea NSPS standards once the revised EG emission limits
are implemented. Due to the resetting of the ``new'' and ``existing''
definitions, any units that meet 40 CFR part 60, subpart Ea
applicability would become existing units subject to the new 40 CFR
part 60, subpart WWWW once implemented through a relevant State or
Federal plan. Additionally, based on changes the EPA has made since
proposal to introduce the new subparts to 40 CFR part 60 for large MWC
regulations, once all existing units are in compliance with the
requirements of 40 CFR part 60, subpart WWWW through a State or Federal
plan, subparts Cb and Eb will no longer be necessary. Therefore, we
intend to reserve all three subparts (40 CFR part 60 subparts Cb, Ea,
and Eb) in a future action for potential use in a future rulemaking
once all large MWC units are in compliance with the requirements of 40
CFR part 60, subpart WWWW through either a State or Federal plan.
2. Changes to Alternative Percent Reduction Standards for Hg, HCl, and
SO<INF>2</INF> and Removal of Emissions Averaging Allowance for
NO<INF>X</INF>
The EPA is not finalizing, as proposed, the removal of the
alternative percent reduction standards, including the 85 percent
reduction allowed for Hg (NSPS and EG), the 95 percent allowed for HCl
(NSPS and EG), and the 80 percent (NSPS) and 75 percent (EG) allowed
for SO<INF>2</INF>. Instead, after considering public comments and upon
further review, we are finalizing recalculated alternative percent
reduction standards based on additional removal efficiency data from
the years 1990 to 1995 for the best performing units used in the
reevaluated MACT standards for Hg, HCl and SO<INF>2</INF>.
The EPA is finalizing, as proposed, the removal of the
NO<INF>X</INF> emissions averaging alternative provided in 40 CFR
60.33b(d)(1) of the existing EG regulation and will not include this
provision in subpart WWWW. Once implementation of subpart WWWW occurs,
sources will no longer be able to comply with applicable requirements
using NO<INF>X</INF> emissions averaging.\55\
---------------------------------------------------------------------------

\55\ See the rationale in section IV.C of this preamble.
---------------------------------------------------------------------------

3. Changes for Optional Continuous Monitoring
The EPA is finalizing, as proposed, the incorporation of new
performance specifications for the optional use of PM CEMS, HCl CEMS or
Hg CEMS in place of stack testing and for the optional use of multi-
metal, PCDD/PCDF CEMS in place of stack tests after promulgation of a
performance specification or approval of a site-specific monitoring
plan. As discussed in the preamble to the proposed rule, in the 2006
final amendments to the large MWC requirements, the EPA revised the PM
and Hg compliance testing requirements to allow the optional use of a
PM CEMS or Hg CEMS in place of stack testing and the optional use of
multi-metal, HCl, PCDD/PCDF CEMS in place of stack tests after
promulgation of performance specifications for these CEMS.\56\ This
final rule incorporates promulgated performance specifications (PS),
including PS-11 (PM), PS-12A (Hg), and PS-12B (Hg).\57\ These updates
do not require a facility that already has an approved site-specific
monitoring plan to incorporate these optional CEMS or to obtain
reapproval of that plan on that basis. If owners and operators use
these optional CEMS for compliance

[[Page 11813]]

demonstration purposes, owners and operators must submit these data to
the EPA in the same manner as data for the required CEMS pollutants
(CO, NO<INF>X,</INF> and SO<INF>2</INF>).
---------------------------------------------------------------------------

\56\ 89 FR 4257 (Jan. 23, 2024); 71 FR 27326 (May 10, 2006).
\57\ Appendix B to Part 60, Title 40.
---------------------------------------------------------------------------

4. Changes To Streamline Regulatory Text Within the Large MWC EG and
NSPS
The EPA is finalizing, with revisions, proposed changes to the
regulatory format of the large MWC standards. The final rule converts
text describing emission standards and performance testing requirements
to tables to facilitate easier implementation and understanding of the
requirements. As noted throughout this section of the preamble, the EPA
is finalizing the large MWC NSPS and EG as new subparts VVVV (Standards
of Performance for Large Municipal Waste Combustors) and WWWW
(Emissions Guidelines and Compliance Times for Large Municipal Waste
Combustors That are Constructed on or Before January 23, 2024), in lieu
of revising existing subparts Cb and Eb. The EPA has converted the
proposed streamlining changes to the new subparts to reduce potential
confusion for affected sources and implementing agencies. The EPA also
developed the new final subparts VVVV and WWWW to update the format and
structure of the regulations to be more accessible, based on Federal
Plain Language Guidelines, and establish section-numbering increments
of five to allow for adequate numeric spacing to revise or add new
regulatory text sections, if needed, in the future.\58\
---------------------------------------------------------------------------

\58\ Federal Plain Language Guidelines: <a href="https://digital.gov/guides/plain-language">https://digital.gov/guides/plain-language</a>.
---------------------------------------------------------------------------

5. Closing the 2007 Proposed Reconsideration of the Large MWC EG and
NSPS
In 2007, the EPA announced that the Agency would reconsider three
aspects of the 2006 final rule in response to requests by stakeholders:
(1) operator stand-in provisions, (2) data requirements for continuous
monitors, and (3) the status of operating parameters during the two
weeks prior to Hg and PCDD/PCDF testing.\59\ In both 2007 and 2024, the
EPA proposed that no changes were necessary to resolve the 2007
reconsideration.\60\ As we received no adverse comments on our proposed
approach, we are now completing action on this reconsideration by
making no changes to these three aspects of the rule.
---------------------------------------------------------------------------

\59\ 72 FR 13016 (Mar. 20, 2007).
\60\ 72 FR 13016 (Mar. 20, 2007); 89 FR 4257 (Jan. 23, 2024).
---------------------------------------------------------------------------

6. Updating Operator Training Examination Requirements
The final rule updates the citation to and incorporates by
reference the American Society of Mechanical Engineers (ASME) Standard
for the Qualification and Certification of Resource Recovery Facility
Operators (QRO) to reflect 2005 updates made to the QRO by ASME. The
rule and text of 40 CFR 60.17(g), 60.5865, and 60.6420 update the
citation to this document and incorporate it by reference as QRO-1-
2005.
7. Revisions to Title V Permitting Requirements for Air Curtain
Incinerators Burning Only Wood Waste, Clean Lumber, and Yard Waste
For air curtain incinerators that burn only wood waste, clean
lumber, yard waste and that are not located at a major source or
subject to title V for other reasons, the EPA is finalizing, as
proposed, removal of the requirement in the 1995 large MWC final rule
that air curtain incinerators that burn only wood waste, clean lumber,
and yard waste and comply with the opacity limits established under CAA
section 129(g)(1)(C)) must apply for and obtain a title V operating
permit.\61\ CAA section 129(e), which requires title V permits for
``solid waste incineration units,'' \62\ does not apply to these ACI
because, as noted in the proposed rule, the definition of ``solid waste
incineration unit'' in CAA section 129(g)(1) ``does not include (C) air
curtain incinerators [that] only burn wood wastes, yard wastes and
clean lumber'' and comply with applicable opacity limits.\63\ CAA
section 502(a) \64\ and the EPA's regulations at 40 CFR 70.3 identify
the types of sources that must obtain a title V permit for operation.
In particular, title V permitting applies to any major source as
defined in 40 CFR 70.2 without exceptions, including ACI that are not
solid waste incineration units under CAA section 129(g)(1) but are
themselves major sources. Based on available data, ACI that burn
exclusively wood waste, clean lumber, and yard waste are commonly
located at facilities that are not major sources and would not
otherwise require a title V operating permit, such as land clearing
operations on public or private land. Further, to the EPA's knowledge,
no large MWC facility operates an ACI that burns exclusively wood
waste, clean lumber, and yard waste on its premises. This final rule
clarifies the applicability of title V permitting requirements for ACIs
that burn exclusively wood waste, clean lumber, and yard waste or a
combination of these materials and comply with the applicable CAA
section 129 opacity limitations and related requirements.
---------------------------------------------------------------------------

\61\ 60 FR 65387 (Dec. 19, 1995).
\62\ 42 U.S.C. 7429(e).
\63\ 89 FR 4258 (Jan. 23, 2024) (quoting 42 U.S.C. 7429(g)(1)).
\64\ 42 U.S.C. 7661a(a).
---------------------------------------------------------------------------

8. Electronic Reporting
The EPA is finalizing, as proposed, a requirement that owners and
operators of large MWC units submit electronic copies of required
performance test reports, performance evaluation reports, semiannual
compliance reports, annual reports, and certain notifications through
the EPA's CDX using CEDRI. Owners or operators must submit performance
test results collected using test methods that the EPA's Electronic
Reporting Tool (ERT) supports, as listed on the ERT website at the time
of the test, and in the format generated through the use of the ERT or
an electronic file consistent with the XML schema on the ERT website.
Owners or operators must submit other performance test results in PDF
format using the attachment module of the ERT.\65\ Owners or operators
must submit performance evaluation results of CEMS measuring relative
accuracy test audit (RATA) pollutants in the format generated through
the use of the ERT or an electronic file consistent with the XML schema
on the ERT website, and must submit performance evaluation results in
PDF format using the attachment module of the ERT. Owners or operators
must submit certain other notifications in CEDRI. For semiannual and
annual reports, the final rule requires that owners and operators use
the appropriate spreadsheet template to submit information to CEDRI.
---------------------------------------------------------------------------

\65\ See ERT Tool: <a href="https://www.epa.gov/electronic-reporting-air-emissions/electronic-reporting-tool-ert">https://www.epa.gov/electronic-reporting-air-emissions/electronic-reporting-tool-ert</a>.
---------------------------------------------------------------------------

The final rule also provides extensions for electronic reporting in
two specific circumstances: (1) outages of the EPA's CDX or CEDRI which
preclude an owner or operator from accessing the system and submitting
required reports, and (2) force majeure events, which the rule defines
as events that have been caused by circumstances beyond the control of
the affected facility, its contractors, or any entity controlled by the
affected facility that prevent an owner or operator from complying with
the requirement to submit a report electronically.\66\ In both
circumstances, the decision to accept

[[Page 11814]]

the request for additional time to report is within the discretion of
the Administrator, and reporting should occur as soon as possible.
---------------------------------------------------------------------------

\66\ See 40 CFR 63.2 (definition of force majeure).
---------------------------------------------------------------------------

9. Technical and Implementation Corrections
The EPA is finalizing corrections and clarifications to the NSPS
and EG that the Agency and stakeholders identified during
implementation of the previous regulations as proposed, with minimal
revisions to accommodate the new subparts.\67\ Specifically, the EPA
includes the proposed clarifications and corrections in the final new
subparts VVVV and WWWW and has updated citations and cross-references
accordingly.
---------------------------------------------------------------------------

\67\ See memorandum entitled Proposed Regulation Edits for 40
CFR part 60, subparts Cb and Eb: Review of the Emission Guidelines
for Existing Sources and New Source Performance Standards: Large
Municipal Waste Combustors Voluntary Remand Response and 5-year
Review, Docket ID No. EPA-HQ-OAR-2017-0183.
---------------------------------------------------------------------------

D. What are the effective and compliance dates of the standards?

The revisions to the NSPS and EG standards that the EPA is
promulgating in this action are effective on May 11, 2026.
The EPA is finalizing the compliance dates of the NSPS and EG as
proposed. Under the final EG and consistent with CAA section 129(b)(2),
revised State plans containing the revised existing source emission
limits and other requirements in the proposed amendments are due within
one year after promulgation of the amendments. States must submit
revised plans to the EPA by March 10, 2027.
The final EG allow existing large MWC units to demonstrate
compliance with the amended standards as expeditiously as practicable
after approval of a State plan, but no later than three years after the
date of approval of a State plan or five years after promulgation of
the revised standards, whichever is earlier. Consistent with CAA
section 129(b)(2), the EPA expects States to require compliance as
expeditiously as practicable. Because we anticipate that several large
MWC units will need to retrofit existing emission control equipment
and/or install additional emission control equipment to meet the final
revised limits, the EPA anticipates that some States may choose to
provide the three-year compliance period allowed by CAA section
129(f)(2).\68\
---------------------------------------------------------------------------

\68\ CAA section 129 does not require or authorize the EPA to
specify the control technology sources must use to meet a numeric
emission limit. The costs are based on assumptions of air pollution
control device retrofits, new equipment, or increased use of sorbent
that may be needed to comply with the emission limits, but owners
will evaluate and use the controls that they determine are necessary
for their source.
---------------------------------------------------------------------------

In revising the standards in a State plan, a State may have two
options, depending on the performance of the large MWC units in that
State. First, a State could include both the 2006 large MWC standards
and the new standards in its revised State plan, which would allow a
phased approach for applying the new emissions limits. The State plan
would clarify that the standards in the 2006 large MWC final rule
remain in effect for large MWC units and apply until the compliance
date of the revised existing source standards (as defined in the State
plan).\69\ Second, a State with existing large MWC units that do not
need to improve performance to meet the revised standards could replace
the 2006 large MWC final rule standards with the standards in this
final rule; follow the procedures in 40 CFR part 60, subpart B and
submit a revised State plan to the EPA for approval. If the revised
State plan contains only the revised standards (i.e., does not retain
the 2006 large MWC final rule standards), the revised standards must be
effective immediately for units subject to the 2006 large MWC final
rule.
---------------------------------------------------------------------------

\69\ All sources currently subject to the 1995 large MWC EG or
NSPS will become existing sources once the final revised large MWC
standards are in place. See section III.B of this preamble for
further discussion.
---------------------------------------------------------------------------

The EPA will revise or replace the existing Federal plan to
incorporate changes to the existing source emission limits and other
requirements that the EPA is promulgating in this action.\70\ The
Federal plan applies to large MWC units in any State without an
approved State plan. The final amendments to the EG allow existing
large MWC units subject to the Federal plan a maximum of five years
after promulgation of the revised standards to demonstrate compliance
with the amended standards, as required by CAA section 129(b)(3).
---------------------------------------------------------------------------

\70\ See 40 CFR part 62, subpart FFF--Federal Plan Requirements
for Large Municipal Waste Combustors Constructed on or before
September 20, 1994.
---------------------------------------------------------------------------

For new sources, the final NSPS requires compliance within six
months after promulgation of this final rule, or upon startup of the
new MWC, whichever is later. This compliance timeline for new sources
is consistent with the requirements of CAA section 129(f)(1).

E. Severability

This final action contains several discrete components, which the
EPA views as severable as a practical matter--i.e., they are
functionally independent and operate in practice independently of the
other components. These discrete components are generally delineated by
the section headings within this section (section III) and section IV
of this preamble. For example, the recalculated MACT floor standards,
calculated using 1990's data, are severable from the 5-year review
standard.\71\ Further, each new or existing source standard for a
specific pollutant is severable from the new or existing source
standard for any other pollutant. The final rule also includes other
revisions to the LMWC NSPS and EG that generally function independently
of one another (e.g., changes to startup, shutdown malfunction
provisions, alternative percentage reduction standards).
---------------------------------------------------------------------------

\71\ As discussed in section IV.A.4, the EPA is finalizing one
standard (50 ppmvd NO<INF>X</INF> limit for new sources) as a result
of the 5-year review.
---------------------------------------------------------------------------

IV. What is the rationale for our final decisions and amendments for
the large MWC source category?

For each issue, this section describes what we proposed and what we
are finalizing, the EPA's rationale for the final decisions and
amendments, and a summary of key comments and responses. The EPA
solicited comment on the proposed rule from January 23, 2024, to March
25, 2024. Specifically, we gathered general comments, additional data,
and information regarding developments in practices, processes, and
control technologies that reduce pollutant emissions as well as
associated costs, feasibility concerns, and other drawbacks. The EPA
subsequently reopened the comment period on the proposal for an
additional four months, from January 16, 2025, to May 30, 2025.
Specifically, we then gathered additional information and documentation
on verifiable historic pollutant emission concentration information
(e.g., stack test reports, waste characterization reports and
continuous emission monitor records) for the source category so we
could further assess the proposed MACT requirements, including
operation of the control technologies over time. For all comments that
this preamble does not discuss, comment summaries and our responses are
available in the comment summary and response document in the
docket.\72\
---------------------------------------------------------------------------

\72\ Docket ID No. EPA-HQ-OAR-2017-0183.

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[[Page 11815]]

A. Five-Year Review and Response to the Voluntary MACT Floor Remand for
the Large MWC Source Category

1. What did we propose based on the five-year review and voluntary MACT
floor remand for the large MWC source category?
a. Emission Limits
In developing the proposed standards, the EPA considered four
scenarios for setting new EG and NSPS emission limits and conducted the
five-year review under CAA section 129(a)(5). In the first scenario, we
considered the MACT floor limits established by the best performing
units for each covered pollutant. In a second scenario, we considered
the appropriateness of additional beyond-the-floor controls for each
covered pollutant. In a third scenario, we evaluated a combination of
MACT floor emission limits for some covered pollutants and limits based
on technology innovations identified in the five-year review for
others. In the fourth scenario, we evaluated a combination of beyond-
the-floor emission limits for some covered pollutants and limits based
on technology innovations identified in the five-year review for
others. As part of the EPA's reevaluation of the MACT floors
established in 1995, we first considered the best performing units to
establish MACT floor limits and then further considered whether beyond-
the-floor controls are appropriate, including by evaluating
improvements in pollution controls and associated costs and other
drawbacks. Following its reevaluation, the EPA proposed standards
resulting from the third scenario, which includes the MACT floor limits
(as assessed and described in section IV.A.1.b of this preamble) for
all covered pollutants except for NO<INF>X</INF>, for which the EPA
proposed to implement more stringent emission standards as a result of
the five-year review. Tables 2 and 3 of the preamble to the proposed
rule present the proposed emission limits.\73\
---------------------------------------------------------------------------

\73\ 89 FR 4251 (Jan. 23, 2024).
---------------------------------------------------------------------------

b. MACT Floor Assessment
As discussed in sections II.B and III.A.2 of this preamble, the EPA
sought and received a voluntary remand of the 2006 revisions to the
large MWC regulations to reevaluate the 1995 MACT floors. In this
rulemaking, the EPA proposed to recalculate the large MWC MACT floors
from its initial analysis in 1995.\74\
---------------------------------------------------------------------------

\74\ Id.
---------------------------------------------------------------------------

While reviewing the data and information originally used to
calculate the 1995 MACT floors, the EPA determined that it did not have
sufficient data from that time period to characterize the performance
of all units necessary to re-evaluate MACT floors. Accordingly, the EPA
proposed to base the calculation of the MACT floors on additional
emissions data from sources in the large MWC source category. The EPA
also proposed to reevaluate the MACT floors based on the state of the
industry at the time the EPA first calculated limits for large MWCs in
1995. The EPA proposed using 1990-1995 performance levels to
reestablish MACT floor requirements to acknowledge the steps that large
MWC facilities took to reduce emissions following the promulgated 1995
standards and to meet the EPA's obligation to correctly set MACT floor
standards for each source category regulated under CAA section 129.
In other words, the EPA accounted for the fact that the 1995
regulations resulted in changes to the operation and APCDs of many
large MWCs in a manner that altered the characteristics of the ``best''
performing units. As explained in the proposed rule, the composition of
the industry remained relatively stable between the promulgation of the
1995 MACT floors and the time of our reevaluation. The EPA thus
proposed to recalculate the MACT floors for large MWCs based on the
population of units operating at the time of the original EG
development (i.e., approximately 1990), taking into account the
installation of APCDs and other improvements sources made to meet the
1995 standards as based on compliance data reported for the same units
from 2000 through 2009. Specifically, the EPA adjusted the initial MACT
floors by assigning default control efficiencies to each APCD
configuration for each covered pollutant, back-calculated an
``uncontrolled'' emissions value from the post-retrofit data, and then
applied the control efficiencies corresponding to pre-retrofit
configurations to estimate emissions that would more accurately
represent the performance level of units operating in 1990. The EPA
subsequently ranked the best performing units within the source
category for each covered pollutant based on the adjusted emissions;
analyzed the data to determine the average performance of those units,
with appropriate accounting for emissions variability; and proposed
MACT floor emission limits.\75\
---------------------------------------------------------------------------

\75\ In calculating MACT floors, for existing sources, CAA
section 129(a)(2) requires that MACT reflect the average emissions
limitation achieved by the best performing twelve percent of units
in the source category; for new sources, MACT limits most be no less
stringent that the emissions control achieved by the best performing
similar unit.
---------------------------------------------------------------------------

The EPA proposed separate methodologies for pollutants having stack
test data (Cd, Pb, Hg, PM, HCl, and PCDD/PCDF) and pollutants having
CEMS data (CO, NO<INF>X</INF>, and SO<INF>2</INF>) due to inherent
differences in the data (i.e., test run data vs. hourly averages). For
each stack test pollutant, we performed a statistical analysis on
annual averages of screened run data from the 2000 to 2009 dataset to
determine UPL, based on the EPA's most recent UPL template (January
2022). For EG limits, we used average annual test data corresponding to
the top 12 percent of units, and for NSPS limits, we used average
annual run data for the single best performer in the UPL
calculations.\76\ The EPA used the most recent UPL template to conduct
the analysis and then rounded up UPL results to two significant
figures.
---------------------------------------------------------------------------

\76\ For PCDD/PCDF, the top performing unit only had enough
reported data to derive two annual averages. In this case, because
the UPL template can only accommodate data sets of n >= 3, the EPA
used unit run data instead of the test average in the UPL
calculation.
---------------------------------------------------------------------------

For CEMS pollutants (CO, NO<INF>X</INF>, and SO<INF>2</INF>), the
EPA proposed that the reported CEMS data already accounted for
emissions variability because the available data consisted of the
reported annual peak 24-hour or four-hour average selected from the
year's CEMS data and represents only the highest end of readings for
the year. We therefore reevaluated limits for CEMS pollutants by
averaging annual peak CEMS data corresponding to the top performers for
each pollutant and applicable subcategory. For NO<INF>X</INF> and CO,
we calculated separate NSPS limits for only two subcategories, MB/WW
and RDF. For NSPS purposes, the EPA assumed that the overarching MB or
RDF subcategories will represent performance of any units built in the
future. We rounded up the resulting averages for CEMS pollutants to two
significant figures. In cases where results were greater (less
stringent) than the current large MWC EG limit, we proposed to retain
the current limit as the MACT floor limit.
The proposed EG and NSPS MACT floor limits for stack test
pollutants and CEMS pollutants and additional information regarding the
EPA's MACT floor assessment are available in section III.A.2 of the
preamble to the proposed rule.\77\
---------------------------------------------------------------------------

\77\ Id.

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

[[Page 11816]]

c. Beyond-the-Floor and Five-Year-Review Results
For assessing beyond-the-floor options in the reevaluation of the
1995 standards, in conjunction with addressing the remand of the
original rule's MACT floors, the EPA proposed to represent the beyond-
the-floor emission limits for existing sources numerically by assuming
that the beyond-the-floor option for existing sources is the new source
MACT floor (emissions control achieved in practice by the best
controlled similar unit, as required by CAA section 129(a)(2)) which is
more stringent than the existing source MACT floor (an average of a
broader range of best performing units, also as required by CAA section
129(a)(2)).
As part of the five-year review pursuant to CAA section 129(a)(5),
to assess additional control options, the EPA evaluated the performance
of, and variability associated with control measures affecting
emissions performance at large MWC sources (including the installed
emissions control equipment) and recent developments in practices,
processes, and control technologies along with associated costs and
other drawbacks. As part of this review, the EPA considered at proposal
developments from the Good Neighbor Plan rulemaking, which found cost-
effective advances in NO<INF>X</INF> control technologies that are
available for the large MWC sector.\78\ The EPA proposed NO<INF>X</INF>
standards, consistent with those finalized in the Good Neighbor Plan as
the CAA section 129(a)(5) five-year review options for consideration
combined with either the MACT floor or beyond-the-floor controls for
the other covered pollutants. Specifically, the EPA's third scenario
consisted of evaluating MACT floor emission limits for all covered
pollutants except NO<INF>X</INF>, which the EPA proposed as a five-year
review emission limit. The EPA's fourth scenario consisted of
evaluating beyond-the-floor emission limits for all pollutants except
NO<INF>X</INF>, which the EPA proposed as a five-year review emission
limit. Based on the EPA's analyses and the findings of the Good
Neighbor Plan, the EPA selected at proposal the MACT floor plus five-
year review approach (scenario three) as the most cost-effective means
to maximize emissions reductions.
---------------------------------------------------------------------------

\78\ 88 FR 36654 (June 5, 2023).
---------------------------------------------------------------------------

In the proposed rule, the EPA found that the 14,200 tpy emissions
reductions achieved by the third scenario (the combination of MACT
floors for all covered pollutants except for NO<INF>X</INF>, which the
EPA proposed updating per the five-year review) are significantly
greater than the reductions achieved by the first scenario (updates to
the MACT floors alone), by approximately 5,020 tpy. The 16,800 tpy
emissions reductions achieved by the fourth scenario (the combination
of beyond-the-floor limits with the updated NO<INF>X</INF> standard
under the five-year review) equal 2,600 tpy in incremental emissions
reduction above those achieved by scenario three. In reviewing the cost
effectiveness of the third and fourth scenarios, the EPA found that the
third scenario included a cost effectiveness of approximately $7,000
per ton emissions reduction of regulated pollutants, while the fourth
scenario resulted in a cost effectiveness of approximately $35,000 per
ton emissions reduction of regulated pollutants. As such, the EPA
proposed that the third scenario--reevaluated MACT floor limits coupled
with the five-year review for NO<INF>X</INF> standards--provided the
most cost-effective means to maximize emissions reductions and was
therefore the most appropriate set of emission standards.
In the proposal, through selection of the third scenario, the
combination of MACT floor emission limits for all covered pollutants
except for NO<INF>X</INF> with the five-year review emission limit, the
EPA recognized that owners or operators have retrofitted most sources
with APCDs that were state of the art for MWCs in the 1990s (i.e.,
spray dryers, fabric filters, and activated carbon injection) for
covered pollutants other than NO<INF>X</INF>. The EPA also believed
that the NO<INF>X</INF> control retrofits that are currently
available--but were not in the 1990s--for most existing large MWCs
appear to be cost-effective (approximately $5,000 to $6,000 per ton)
and technically feasible for several existing large MWC units currently
operating in the U.S. More details on the cost effectiveness of the
options considered are in the memorandum entitled Compliance Cost
Analyses for Large MWC Final Rule Amendments in the docket for this
rulemaking.
The EPA proposed the 110 ppmvd (24-hour) NO<INF>X</INF> limit
consistent with the NO<INF>X</INF> limit finalized under the Good
Neighbor Plan based on the application of ASNCR or Covanta
LNTM NO<INF>X</INF> technology, finding that this limit was
cost effective for existing units outside of the Ozone Transport Region
that the Good Neighbor Plan did not cover; separately, in the Good
Neighbor Plan, the EPA found that the limit was cost-effective for
units inside of the Ozone Transport Region.\79\ Unlike the Good
Neighbor Plan, the EPA did not propose a mechanism for existing large
MWCs to request a case-by-case emission limit based on a demonstration
that application of ASNCR and Covanta's LNTM Technology or
any other NO<INF>X</INF> emission reduction technologies or measures is
not technically feasible.
---------------------------------------------------------------------------

\79\ Id.
---------------------------------------------------------------------------

For all new units, the EPA proposed a NSPS NO<INF>X</INF> limit of
50 ppmvd (measured in 24-hour period). The EPA based this limit on the
permitted NO<INF>X</INF> limit for the only facility currently using
SCR technology with an air-to-air heat exchanger providing flue gas
reheat prior to entering the SCR reactor to represent the five-year
review standard for new sources. The EPA determined that owners or
operators only reasonably can apply this design during construction of
the unit, so retrofitting SCRs to other existing units would be
technically infeasible and/or very costly if provision of reheat
requires use of a supplemental burner.
Although the EPA considered other potential improvements that could
be technically feasible for large MWCs as part of the five-year review,
including circulating fluidized bed scrubbers (CFBS) for acid gas
control and oxidation catalysts for CO control, we did not propose
standards based on the performance improvements these technologies
might yield. The EPA determined that retrofitting existing large MWC
units with CO oxidation catalysts would be prohibitively costly, as
accommodating an entirely new piece of equipment in the APCD system
would require new facility footprint space and flue gas routing. For
CFBS, the EPA acknowledged that although theoretically owners or
operators could replace existing acid gas control devices with a CFBS
to achieve slightly better acid gas control, the EPA lacked data
demonstrating technical feasibility for new or existing MWC units.
2. How did the proposed emission limits and MACT floor assessment
change for the large MWC source category?
As introduced in section III.A of this preamble, the EPA has
revised its MACT floor assessment for the EG and NSPS in response to
new data and associated comments since the proposal. The EPA is
finalizing the same fundamental analytical approach as proposed,
specifically using separate methodologies for pollutants with stack
test data (Cd, Pb, Hg, PM, HCl, and PCDD/PCDF) and pollutants with CEMS
data (CO, NO<INF>X</INF>, and SO<INF>2</INF>). For each stack

[[Page 11817]]

test pollutant, the EPA performed a statistical analysis on annual
averages of screened run data to determine a UPL. For CEMS pollutants,
we averaged peak annual values, maintaining its stance that the data in
this form already account for emissions variability. For EG limits, we
used data corresponding to the top 12 percent of units, and for NSPS
limits, we used data for the single top performer, consistent with CAA
section 129(a)(2).
The emissions test data that the EPA used for the UPL analyses for
stack test pollutants includes the 2000 through 2009 compliance data
and newly received data from 1990 through 1995. The EPA made minor
revisions to the 2000 through 2009 data set based on comments received.
The 1990s data came from test reports and related documents submitted
via email to the EPA in 2024 and 2025 by the WTEA or from attachments
to comments submitted to the docket. The EPA assessed the performance
of large MWCs operating in 1990 primarily based on the 1990s data.
However, these data accounted for 75% of units operating in 1990, so we
filled data gaps, where possible, based on adjusted emissions data from
the 2000s dataset. Similar to the approach used at proposal, we
accounted for performance improvement over time by adjusting the 2000
through 2009 emissions data to reflect 1990s performance. In the
revised analysis, the EPA used paired 1990s and 2000s data to inform
its adjustment factor development based on combustor/APCD combinations
rather than relying on default APCD efficiencies alone, as the EPA did
at proposal.
For the NSPS analysis for stack test pollutants, the EPA revised
the UPL approach to address variability concerns raised by commenters
regarding the limited number of data points available for the top
performers. For every stack test pollutant, only one test was available
for the top performer. To account both for more recent operational
practices and waste characteristics that a single test from the 1990s
may not sufficiently characterize and for the fact that we could not
obtain additional years of data from the early 1990s, we assessed the
distribution and variance of 2000s test averages (i.e., data from
several years) for the same performer. In all cases, the 2000s data
distribution matched the 1990s distribution, and the EPA combined
variance of the 2000s data with the variance of the 1990s data in the
UPL calculation.
For CEMS pollutants, the EPA made no changes to the MACT floor
calculation methodology; however, revisions to the dataset as described
in this section yielded a new EG limit for SO<INF>2</INF> and a new
NSPS limit for CO for mass burn waterwall units. Further details
regarding the revised MACT floor assessment are provided in the LMWC
MACT Floor memorandum for the final rule.\80\
---------------------------------------------------------------------------

\80\ See memorandum entitled MACT Floor Calculations for Large
Municipal Combustor Units--Final Rule, available at Docket ID No.
EPA-HQ-OAR-2017-0183.
---------------------------------------------------------------------------

For the five-year review and beyond-the-MACT floor approaches, the
EPA is not finalizing our determinations as proposed for existing
units, meaning that the EPA is not basing the NO<INF>X</INF> standard
on the findings of our five-year review. Tables 2 and 3 of this
preamble present the resulting final emission limits.
3. What key comments did we receive on the emissions limits, MACT floor
assessment, beyond-the-floor, and five-year review, and what are our
responses?
Comment: The EPA received numerous comments on the proposed control
factor adjustment approach to emulate data from large MWCs that were
operating in 1990 for reevaluating the original MACT floor. Commenters
suggested that the EPA's proposed approach did not adequately
characterize operational and waste composition differences from the
2000-2009 timeframe to the early 1990s and urged the EPA to use actual
data from the 1990s to better inform any adjustments or calculations.
Several commenters provided emission tests, spreadsheets, or test
report summaries with emissions test information for a portion of the
large MWC units in operation in 1990, as well as for some units that
came into operation after that time but had performance data from the
early 1990s. These industry commenters also provided some emissions
test summary data from units within the 2000-2009 timeframe, consisting
mainly of test averages for years and units for which we did not
already have data in the 2000-2009 database. Other commenters argued
that the EPA should not adjust the emissions data to reflect less
protective performance and should not limit the reevaluation of the
MACT floor to units operating in 1990, stating that this approach
ignores better equipment and performance exhibited by newer large MWCs
and that the five-year review requires use of newer units' data.
Response: The EPA agrees with commenters' arguments that adjusting
post-compliance data based purely on expected APCD performance may not
adequately reflect differences in waste composition or operational
improvements from the 1990s to the 2000-2009 compliance data in the
EPA's database. The EPA therefore reopened the comment period for
commenters to compile and submit available data from the 1990s. The
data received during the additional comment period significantly
increased the amount of information available to evaluate performance
in the 1990s, especially in cases where no data was available for a
unit. The additional data also allowed the development of a more robust
adjustment factor to apply to 2000-2009 compliance data.
The EPA assessed the performance of large MWCs operating in 1990
primarily based on the 1990s data. However, these data accounted for
75% of units operating in 1990, so the EPA filled data gaps, where
possible, based on adjusted emissions data from the 2000s dataset.
Similar to the approach used in the proposal, the EPA accounted for
performance improvement over time by adjusting the 2000s emissions data
to reflect 1990s performance. In the revised analysis, we used paired
1990s and 2000s data to inform its adjustment factor development on
combustor/APCD combinations rather than relying on default APCD control
efficiencies alone, as we did at proposal.
For the NSPS analysis for stack test pollutants, the EPA revised
the UPL approach to address variability concerns that commenters raised
regarding the limited number of data points available for the top
performers. For every stack test pollutant, only one test was available
for the top performer. To account both for more recent operational
practices and waste characteristics that a single test from the 1990s
may not sufficiently characterize and for the fact that we could not
obtain additional years of data from the early 1990s, we assessed the
distribution and variance of 2000s test averages (i.e., data from
several years) for the same performer. In all cases, the 2000s data
distribution matched the 1990s distribution, and we combined the
variance of the 2000s data with the variance of the 1990s data in the
UPL calculation.
For CEMS pollutants, the EPA made no changes to the MACT floor
calculation methodology; however, revisions to the dataset yielded a
new EG limit for SO<INF>2</INF> and a new NSPS limit for CO for mass
burn waterwall units.
The EPA disagrees with some commenters' argument that using data
from more recently constructed units to

[[Page 11818]]

establish the MACT floor is appropriate here, as that suggested
approach would characterize best performers that were already in
compliance with the existing MACT standards. The goal of the remand is
not to calculate MACT on top of the existing MACT but to reevaluate the
original standards to ensure they appropriately reflect MACT when
initially promulgated.\81\ Thus, the analysis continues to reflect only
units that were operating in 1990 because the EPA is reevaluating this
original MACT floor as part of this rulemaking. Further, we have not
changed our approach to using the UPL for calculating stack test
pollutant emission limits and the average of the highest annual values
for the best performers for the CEMS pollutants (CO, NO<INF>X</INF>,
SO<INF>2</INF>), although we have reevaluated the data for the units
identified in the proposal as best performers.\82\ Additional specific
comments on various aspects of the emission limit calculation approach,
such as use of the UPL, subcategorization and other approaches to
addressing variability are in section 4.0 of the Comment Response
Document in the docket for this rulemaking.
---------------------------------------------------------------------------

\81\ See U.S. Sugar Corp., 113 F.4th 984 (upholding the EPA's
decision to rely on original dataset to correct prior MACT standards
errors and recalculate MACT floor during remand); cf. Med. Waste
Inst. Energy Recovery Council v. EPA, 645 F.3d 420 (D.C. Cir. 2011)
(holding that the EPA was reasonable in its decision to use post-
compliance data to reset MACT floor during remand after concluding
that the prior dataset was flawed).
\82\ See comment and response below on NSPS CO emission limit
for further discussion.
---------------------------------------------------------------------------

Comment: Commenters argued that the proposed new source limits do
not consider the variability of waste streams from different
communities as well as seasonal variation within a community. One
commenter proposed that the EPA base the variance on the top 12% of
units identified for development of the MACT floors for existing units
to provide a more representative estimate of variability, given the
lack of actual data. Other commenters stated that the EPA's UPL
approach for stack test pollutants limits the data set to only a
handful of tests and leads to an extremely high calculation of
variability under the extreme (99th percentile) UPL employed. These
commenters asserted that in the past, the EPA has instead set ``beyond-
the-floor'' limits for units where the 99th percentile UPL for the
single ``best'' unit was less stringent than the UPL for the average of
the top 12 percent.
Response: The EPA recognizes that there is some merit to the
argument that a single emissions test taken more than 30 years ago may
not accurately characterize waste and operational variability that a
large MWC unit may see on a day-to-day basis. Further, we acknowledge
that, after extensive industry efforts to collect legacy emissions data
from the 1990s, the best performing units each only have a single
emissions test reflecting performance at that time, and there are not
additional tests from that timeframe available that we could use to
gauge waste variability impacts in the 1990s. To address these
commenters' concerns, we have reviewed the available 2000-2009 data for
the best performing units, for which several years of data are
available. The EPA compared the variance observed for the best
performing units' 1990s data and 2000s data and found them to be the
same distribution type and so we replaced the variance from the single
1990s emissions test with the variance observed from the multiple year
2000s data set available for the best performer in the UPL calculation.
The resulting limits therefore incorporate variance observed over
multiple years, which presumably would incorporate waste variance, and
apply this variance to the UPL calculation using 1990s emissions data.
The resulting limits are more stringent than the reevaluated EG MACT
floors, so beyond-the-floor emission limits suggested by commenters are
not necessary for the stack test pollutant limits calculated using UPL
methodology.\83\
---------------------------------------------------------------------------

\83\ To represent beyond-the-floor emission limits numerically,
we assumed the new source MACT floor (i.e., emissions control
achieved in practice by the best controlled similar unit) as the
emission limit applied to existing sources. From a cost-
effectiveness viewpoint, the beyond-the-floor/5-year review scenario
was five times more costly with less incremental emissions
reductions of regulated pollutants. For further discussion of the
rationale, see section III.A.3 of the preamble to the proposed rule.
---------------------------------------------------------------------------

Comment: Commenters questioned the data that the EPA used to
calculate the NSPS CO emission limit for MB/WW units and questioned the
validity of the low CO emissions reported for the Wheelabrator
Bridgeport large MWC. Commenters added that the proposed 16 ppmvd
emission limit is unachievable.
Response: Acknowledging differences in the reporting method for the
Wheelabrator Bridgeport data from the data submitted for other sources,
the EPA assessed whether it was appropriate to consider the
Wheelabrator Bridgeport data as part of the larger dataset that
included other submissions. The EPA performed a paired t-test analysis,
using ProUCL software, of the three Wheelabrator Bridgeport units
against the rest of the best performers in order to determine whether
these units are in fact representative of the best performers or
whether they are a statistically distinct dataset. The paired t-test
indicates that, at the 99.9 percent confidence coefficient, there are
two distinct populations of data--those from Wheelabrator and those for
the other units. Figure 1 depicts the two distinct data sets.

Figure 1. Probability Distribution Function of Adjusted Raw CO 1990
Data

[[Page 11819]]

[GRAPHIC] [TIFF OMITTED] TR10MR26.124

There are no known operational differences that would cause the
Wheelabrator Bridgeport units to be distinct from the rest of the best
performers. Wheelabrator Bridgeport did not report emissions that
occurred during SSM, which is inconsistent with the new standard (which
includes periods of SSM), while other units included SSM data. While
emissions of covered pollutants are typically low during periods of
startup and shutdown because no waste has been added to the large MWC,
this is not always true of CO because low emissions of CO in a
combustor is an indicator of good combustion efficiency. The goal of
warmup and startup in a combustor is to establish steady-state,
maintainable good combustor efficiency to begin normal operations;
before the combustor reaches steady-state, the CO emissions can vary
widely with the changes in the combustion environment characteristic of
warmup, startup, and shutdown. For large MWCs, annual maximum average
CO emission concentrations frequently occur during periods of SSM.\84\
The EPA finds it most likely that the low reported concentrations in
data from the Wheelabrator Bridgeport units exclude emissions during
periods of SSM, which other facilities include in their reported data.
We attribute this likely exclusion to the reporting requirements of the
applicable rule. Specifically, although the NSPS and EG, subparts Eb
and Cb only require regulated facilities to report the maximum average
during the year, some State and local agencies require the reporting of
all periods of operation, and others require reporting only during
normal operations. Because the EPA therefore determined that the
Wheelabrator Bridgeport data from the CEMS dataset are
nonrepresentative and not appropriately comparable to data from units
whose reported emissions data included SSM periods, we removed the
Wheelabrator Bridgeport data from the dataset and redetermined the best
performers and the associated MACT floor. This approach resulted in a
NSPS CO emission limit of 76 ppmvd and an EG SO<INF>2</INF> emission
limit of 22 ppmvd, because the EPA had identified the Wheelabrator
Bridgeport units as the best performer for CO and within the top 12
percent of best performers for SO<INF>2</INF> at proposal and these
data were excluded from the dataset in this final rule.
---------------------------------------------------------------------------

\84\ This is why we are finalizing that CEMS data collected
during warmup, startup, or shutdown periods will be averaged at
stack oxygen content and not corrected to seven percent oxygen, as
are data during normal operations.
---------------------------------------------------------------------------

Comment: Commenters both supported and criticized the five-year
review finding that there are cost-effective methods such as ASNCR
technology and Covanta's LNTM Technology, available for
existing units to meet a 110 ppmvd emission limit for NO<INF>X.</INF>
Some commenters suggested a more stringent NO<INF>X</INF> limit based
on the application of hybrid selective noncatalytic reduction (SNCR)
and SCR.
Response: The EPA is not finalizing the proposed NO<INF>X</INF>
emission limit of 110 ppmvd for existing large MWCs due primarily to
the large capital expense (more than $412 million) that the EPA
reasonably anticipates for the existing large MWC source category as a
whole. As noted previously, the stay of the Good Neighbor Plan means
costs to comply with this standard would be higher than previously
estimated and the emissions reductions estimates are more uncertain
than previously believed. At proposal, the EPA excluded units that we
expected the Good Neighbor Plan to cover from the capital cost
estimate, which was $257 million for the remaining units. The inclusion
of those previously excluded units increases the total estimated
capital cost to $412 million. The EPA recognizes that this industry
provides public services, and these large capital expenditures on the
industry could be challenging, especially for municipalities that own
large MWCs or parent companies that operate multiple large MWC
facilities.
In addition, the EPA recognizes significant uncertainty in the
emission reductions and cost effectiveness estimates from proposal,
based on a likely overestimation when using the average of peak 24-hour
CEMs data to calculate baseline NO<INF>X</INF> emissions. We are,
however, maintaining the proposed 50 ppmvd NO<INF>X</INF> limit for new
sources within the NSPS based on the availability and continued
operation of a large MWC unit equipped with SCR controls.\85\ Regarding
SNCR-SCR hybrid

[[Page 11820]]

technologies, limited information is available about application of
these technologies, and no information is available about long-term
performance of these controls applied to municipal waste combustors.
However, the final standards do not specify the controls that owners
and operators must use to meet the emission limits for NO<INF>X</INF>,
and owners or operators may investigate whether an SNCR-SCR hybrid
system is a viable option for their emission control needs.
---------------------------------------------------------------------------

\85\ See memorandum entitled Clean Air Act Section 129(a)(5) 5-
Year Review for the Large Municipal Waste Combustor Source Category,
available in docket EPA-HQ-OAR-2017-0183. Also note that the Good
Neighbor Plan supporting documentation came to similar conclusion:
``[T]he study concluded that there are significant space
considerations with SCR system installation which can be managed in
a cost effective way in a new development, but which make retrofit
installation very costly and complex.'' Municipal Waste Combustor
Workgroup Report (Revised May 2023), Ozone Transport Commission
Stationary and Area Sources Committee: <a href="https://otcair.org/upload/Documents/Reports/OTC%20MWC%20report%20revised%205_2023.pdf">https://otcair.org/upload/Documents/Reports/OTC%20MWC%20report%20revised%205_2023.pdf</a>.
---------------------------------------------------------------------------

4. What is the rationale for our final approach?
The underlying approach to and premise for our reevaluation of the
1995 MACT floors as described in the proposed rule remains the same. As
discussed in sections II.B and III.A of this preamble and in the
proposed rule, the EPA has recalculated the large MWC MACT floors using
actual 1990-1995 test data in order to correct the EPA's 1995 analysis
of MACT floors to account for case law questioning standards based on
State-issued permit levels without evidence that the permit levels
reflect the performance of the best performing sources. In
recalculating the 1995 MACT floors to correct errors in our initial
analysis, the EPA is assessing the state of the industry at the time
that we first calculated limits for large MWCs. Given the history of
limited data availability of this source category, the EPA views this
approach as appropriate to establish MACT floors that reflect the
emission levels actually achieved by the best performing sources using
the MACT before sources in the category first complied with the 1995
standards. The EPA determined that utilizing 1990s performance levels
to reestablish MACT floor requirements appropriately balances competing
interest in this rulemaking, by recognizing on one hand that large MWC
facilities have taken steps to reduce emissions since the EPA first
promulgated 1995 standards, and on the other hand the EPA's obligation
to correctly set MACT floor standards for each source category
regulated under CAA section 129. At proposal, the EPA determined that
it did not have sufficient data from the 1990s to characterize the
performance of all units during that time period and that it was
necessary to utilize a different dataset to recalculate new MACT floors
from the one used to set the initial MACT floors in 1995. Emissions
data received during the public comment periods allowed the EPA to
develop a 1990-1995 data set, which the EPA used in conjunction with
the 2000-2009 compliance data to better reflect 1990s performance when
reevaluating the MACT floors for the final rule.\86\
---------------------------------------------------------------------------

\86\ The EPA further notes that this approach is consistent with
the congressional design of CAA section 129, which envisioned the
calculation and implementation of MACT floors for this source
category through rulemaking by 1990. See 42 U.S.C. 7429(a)(1)(B).
---------------------------------------------------------------------------

In the related context of hospital, medical, and infectious waste
incinerators (HMIWI) also regulated under CAA section 129, the EPA
issued a rule on remand from the D.C. Circuit to further explain our
reasoning in determining MACT floors for new and existing HMIWI.\87\ In
that situation, after the original MACT floors went into effect for
HMIWI, approximately 94 percent of HMIWI units shut down, and an
additional three percent of units obtained exemptions from the
regulations.\88\ Because of these significant changes in the regulated
industry, we were not confident in using much of the same data used to
set the original MACT floors, in part because data were unavailable
from the many units that shut down following promulgation of the
original standards. The EPA instead found ``the best course of action
[was] to re-propose a response to the remand based on data from the 57
currently operating HMIWI.'' \89\ Subsequently, in reviewing the EPA's
recalculated MACT floors for HMIWI, the D.C. Circuit found that
``[w]hen the EPA determined that its regulation rested on unreliable
data and that it had to reset the floors, the Agency was functionally
regulating on a blank slate even though the regulation continued to
remain on the books.'' \90\
---------------------------------------------------------------------------

\87\ 74 FR 51368 (Oct. 6, 2009).
\88\ 72 FR 5510, 5518 (Feb. 6, 2007).
\89\ 73 FR 72962, 72970 (Dec. 1, 2008).
\90\ Med. Waste Inst. & Energy Recovery Council, 645 F.3d 420.
---------------------------------------------------------------------------

The EPA is also functionally establishing new MACT floors for large
MWCs on a blank slate because the 1995 MACT floors were originally
calculated using a data set--state air permitting levels--that was not
appropriate absent evidence of actual emissions. Unlike in the HMIWI
rulemaking, however, there have not been significant retirements in the
large MWC industry since we first introduced standards in 1995, and the
industry today consists largely of the same units that were operating
before the original MACT floors went into effect. Instead of
retirements, the majority of the industry installed APCD and made other
improvements to meet the 1995 standards. Because the industry today
consists of largely the same units that were operating in 1995, we are
able, as proposed, to calculate revised MACT floors for large MWCs that
are appropriate for the current fleet, based on the industry's 1995
performance level.
Sections III.A.2 and IV.A.2 of this preamble explain the data and
methodology the EPA used to reevaluate the MACT floors for large MWCs.
In general, the EPA has used the 1990s emissions data to the fullest
extent possible considering the documentation available for the data.
For example, the EPA used emissions concentration data extracted from
emission test reports, test report executive summaries, and State-
provided compliance data that contained sufficient information to
convert the data into useable and consistent units of measure (i.e.,
mg/dscm at seven percent O<INF>2</INF>) for use in the UPL calculations
in lieu of adjusting 2000-2009 data, as done at proposal. In
calculating the MACT floors, we did not use data that was provided in
the form of emission factors (e.g., lb/ton MSW) or emission rates
(e.g., lb/hr) and that lacked sufficient supporting test data to
convert to consistent units of measure without use of default F-factors
or heat input rates. Recognizing that 1990s data were unavailable for
some of the units in operation in 1990, the EPA filled data gaps by
adjusting the 2000-2009 data for each of the units as necessary using
data adjustment factors. Unlike at proposal, the EPA used paired 1990s-
2000s data for similar combustor types and APCD configurations to
develop the data adjustment factors. These factors thus reflect all
differences in waste and operational methods from the 1990s and 2000s,
and the EPA was able to better adjust the 2000s data accordingly to
approximate performance in the 1990s when earlier data are unavailable
for specific units.
The EPA did not change the UPL calculation methodology for the EG
MACT floor standards from proposal, but recognized that the best
performers used for calculating the NSPS standards for stack test
pollutants only had one test available from the 1990s. The EPA
acknowledged that municipal waste streams are a uniquely variable fuel
source with numerous factors that can directly impact emissions (such
as seasonal changes in waste composition or consumer habits), and one
stack test

[[Page 11821]]

may not sufficiently reflect this inherent waste variability.
Considering that sources collected these data three decades ago and
that obtaining additional data from the 1990s to evaluate variability
at the unit over that time period was not possible, we reviewed the
2000-2009 data available for the best performers. The EPA compared the
variance and population distribution of the sole 1990s test data to the
multiple years of data available from the 2000s for the best performers
and found them to be of the same distribution type. Therefore, to
ensure that longer-term waste variability is adequately addressed in
this unique situation, we incorporated the variance data from the 2000s
data for the best performers into the UPL equations, using the 1990s
emissions data to develop the NSPS MACT floor emission limits.
Likewise, the EPA analyzed the data from the CO best performer at
proposal (CEMS data from Wheelabrator Bridgeport units) and, as
described in section III.A.2 of this preamble, determined that these
data are statistically unique from the remainder of the large MWC
fleet's data due to the probable non-reporting of data during SSM.
Therefore, the EPA has excluded the Wheelabrator Bridgeport CEMS data
from the CEMS pollutant MACT calculations.
Finally, after review of comments and considering the stay of the
Good Neighbor Plan, the EPA is not finalizing the results of our five-
year review as proposed. Mainly, the EPA is setting the emission
standards for NO<INF>X</INF> at the reevaluated MACT floor level
instead of the 110 ppmvd limit based on the five-year review proposed
for large MWCs in light of the then-effective Good Neighbor Plan and
the performance observed by some existing large MWC units operating in
the U.S. currently. While the standards do not prescribe a particular
control technology, as we discuss in the preamble to the proposed rule,
existing sources have used ASNCR and Covanta's LN\TM\ technologies to
achieve the 110 ppmvd performance. We evaluated the costs associated
with this performance level,\91\ and we have the following concern:
application of these controls to the remaining population of existing
large MWCs would result in an expected $411.6 million capital
expenditure by the large MWC sector, which in turn owners or operators
potentially would pass forward, resulting in tipping fee increases or
potential unit closures for municipalities that utilize large MWCs for
the MSW disposal needs.\92\
---------------------------------------------------------------------------

\91\ See memorandum entitled Compliance Cost Analyses for Large
MWC Final Rule Amendments, Docket ID No. EPA-HQ-OAR-2017-0183.
\92\ See id.
---------------------------------------------------------------------------

The EPA does not see this situation for large MWC sources that have
yet to commence construction. As noted at proposal, a facility designed
with SCR NO<INF>X</INF> controls has been operating successfully for
several years. Nothing in the comments suggests that future large MWC
unit construction could not do the same. Therefore, we are maintaining
the proposed 50 ppmvd NO<INF>X</INF> limit for NSPS units. Specific
comments on and associated responses to comments on the emission limit
calculation and 5-year review methodology and results are provided in
the Comment Response Document in the docket for this rulemaking.

B. Startup, Shutdown, and Malfunction

1. What did we propose pursuant to SSM provisions for the large MWC
source category?
The EPA proposed revisions to the SSM provisions of the large MWC
NSPS and EG to ensure that these provisions are consistent with the
D.C. Circuit's decision in Sierra Club. In that decision, the court
vacated an SSM exemption in a CAA section 112 regulation after
concluding that, pursuant to the definition of ``emission standard''
and ``emission limitation'' in CAA section 302(k), emissions standards
or limitations under CAA section 112 must apply continuously and that
the SSM exemption violated the CAA's requirement.\93\ The EPA proposed
that the reasoning in Sierra Club applies equally to CAA section 129
because the definition of ``emission standard'' in CAA section 302(k)
also applies to emission standards and limitations established pursuant
to CAA section 129.
---------------------------------------------------------------------------

\93\ 551 F.3d 1028 (vacated the SSM exemptions that were
codified at 40 CFR 63.6(e)(1), (f)(1) and (h)(1)).
---------------------------------------------------------------------------

The EPA did not propose a separate emission standard for large MWC
units during periods of startup and shutdown. We determined that large
MWC units would be able to meet the emission limits during periods of
warmup and startup because most units use natural gas or clean
distillate oil to warm up the unit and do not add waste until the unit
has reached combustion temperatures during a brief startup period.
Emissions from burning natural gas or distillate fuel oil would
generally be significantly lower than from burning solid wastes, for
most pollutants, specifically those where owners or operators measure
compliance by using stack tests (e.g., Cd, Pb, Hg, PM, PCDD/PCDF, and
HCl). Further, because we accounted for emissions variability and
proposed appropriate averaging times to determine compliance with the
revised MACT standards, we believed we adequately addressed any minor
variability that may occur during startup or shutdown.
The EPA also proposed to eliminate the exclusions of periods of
warmup, startup, and shutdown from CEMS data averaging calculations
present in the 1995 large MWC rules for NO<INF>X</INF>, SO<INF>2</INF>,
and CO and replace them with a monitoring and compliance demonstration
approach used in the more recent CAA section 129 rulemaking for CISWI
NSPS and EG.\94\ We proposed that owners or operators must collect and
report CEMS data whenever the large MWC unit is operating. Periods when
the combustor is operating but owners or operators are not recording
monitoring data due to monitor malfunctions may be considered
deviations.\95\ We proposed that owners or operators flag CEMS data
collected while the large MWC unit is warming up, starting up, and
shutting down as warmup, startup, or shutdown period data. We proposed
that owners or operators must use the CEMS data for the warmup period
and up to three hours of allowable startup or shutdown time per
occurrence to calculate rolling or block average values but average
these at stack oxygen content instead of at a seven percent
O<INF>2</INF> diluent cap. We requested comment on whether we should
adopt a 30-day hourly rolling average for demonstrating compliance for
pollutants measured using continuous monitoring, similar to provisions
that the EPA has promulgated in many recent combustion standards, such
as in CISWI, the Mercury Air Toxics Standards, and the National
Emission Standards for Hazardous Air Pollutants for Major Sources:
Industrial, Commercial and Institutional Boilers and Process
Heaters.\96\
---------------------------------------------------------------------------

\94\ 84 FR 15846 (Apr. 16, 2019).
\95\ This excludes periods of system breakdowns, repairs, and
required routine monitor calibrations or quality assurance/quality
control periods, according to 40 CFR 60.13(e).
\96\ Mercury Air Toxics Standards (40 CFR part 63, subpart
UUUU); Commercial and Institutional Boilers and Process Heaters (40
CFR part 63, subpart DDDDD).
---------------------------------------------------------------------------

Periods of startup, normal operations, and shutdown are predictable
and routine aspects of a source's operations. Malfunctions, in
contrast, are neither predictable nor routine. Instead they are, by
definition, sudden, infrequent, and not reasonably preventable failures

[[Page 11822]]

of emissions control, process, or monitoring equipment.\97\ The D.C.
Circuit in U.S. Sugar Corp. upheld the EPA's position that CAA section
112 does not require the Agency to include emissions that occur during
periods of malfunction when developing CAA section 112 MACT
standards.\98\ We proposed that the reasoning in U.S. Sugar Corp.
applies equally to section CAA 129 standards given the similarities
between the section 112 and 129 standard setting criteria.
---------------------------------------------------------------------------

\97\ See 40 CFR 63.2 (definition of malfunction).
\98\ 830 F.3d at 606-10.
---------------------------------------------------------------------------

2. How did the proposed startup, shutdown, and malfunction provisions
change for the large MWC source category?
The EPA is finalizing the proposed revisions to the SSM provisions
of the NSPS and EG. We received comments both supporting and opposed to
the proposed approach, but none presented sufficient information to
cause us to determine that the approach proposed would be unachievable
for large MWC units or otherwise as inappropriate. Moreover, in
Environmental Committee of the Florida Electric Power Coordinating
Group, Inc. v. EPA, the D.C. Circuit recognized that similar to CAA
section 112, CAA section 129(a)(1)(A) requires the use of ``emission
limitations'' consistent with the CAA section 302(k) definition.\99\
This further supports finalizing the proposed revisions to the SSM
provisions consistent with the D.C. Circuit's decision in Sierra Club.
---------------------------------------------------------------------------

\99\ 94 F.4th 77, 103 (D.C. Cir. 2024).
---------------------------------------------------------------------------

We note that large MWC units operating in Florida have operating
permits with practically the same requirements for startup and shutdown
events as those the EPA proposed. For example, the Covanta Lake II,
Inc. facility has limits that apply during startup and shutdown but
``[t]hese limits do not utilize any diluent correction.'' \100\
Specific comments and associated responses to the SSM provision
revisions are in the Comment Response Document in the docket for this
rulemaking.
---------------------------------------------------------------------------

\100\ See the Covanta Lake II, Inc. Startup-Shutdown-Malfunction
Emission Limit Project, Permit No. 0690046-017-AC, Docket ID EPA-HQ-
OAR-2017-0183.
---------------------------------------------------------------------------

C. Other Changes to the Large MWC EG and NSPS

1. Changes to the Applicability Date of the 1995 Large MWC EG and NSPS
a. What did we propose regarding applicability dates for the large MWC
source category?
The EPA proposed new applicability dates for determining whether
units are ``existing'' or ``new'' sources. Specifically, we proposed
that large MWC units that are currently subject to the NSPS would
become existing sources under the proposed amended standards and
subject to the revised EG by the applicable compliance date for the
revised guidelines. However, those units would continue to be NSPS
units subject to the 1995 large MWC final rule until they become
subject to the amended existing source EG. We proposed that large MWC
units that commence construction after the date of the proposal, or for
which a modification is commenced on or after the date six months after
promulgation of the amended standards, would be new units subject to
the NSPS emission limits. Units for which owners or operators commence
construction or modification prior to those dates would be existing
units subject to the proposed EG.
As discussed in section III of this preamble, the EPA proposed to
reserve 40 CFR part 60, subpart Ea standards, which apply to units for
which construction commenced after December 20, 1989, and on or before
September 20, 1994. The EPA proposed that any units that meet subpart
Ea applicability would become existing units subject to the EG once
implemented through a State or Federal plan.
b. How did the proposed revisions to the applicability dates change for
the large MWC source category?
The EPA did not receive comments on the proposed resetting of the
applicability dates, so we are finalizing these revisions as proposed.
However, as noted earlier in the preamble, we recognize that the Agency
may need subparts Cb and Eb at a future date once all large MWC units
are complying with the requirements of subpart WWWW through an approved
State plan or the Federal Plan. Therefore, we intend to reserve all
three subparts (40 CFR part 60, subparts Cb, Ea, and Eb) in a future
rulemaking once all large MWC units are in compliance with the
requirements of 40 CFR part 60, subpart WWWW via either State plan or
Federal plan means of implementation.
2. Changes to Alternative Percent Reduction Standards for Hg, HCl, and
SO<INF>2</INF>, and Removal of the Emissions Averaging Allowance for
NO<INF>X</INF>
a. What did we propose regarding changes to alternative percent
reduction standards for the large MWC source category and emissions
averaging allowances for NO<INF>X</INF>?
The EPA proposed to remove all alternative percent reduction
standards that the original 1991 final rule allowed, including the 85
percent reduction allowed for Hg (NSPS and EG), the 95 percent allowed
for HCl (NSPS and EG), and the 80 percent (NSPS) and 75 percent (EG)
allowed for SO<INF>2</INF>. We proposed to remove the alternative
standards based on limited data available in the large MWC emissions
database to evaluate for the alternative percent reduction standards
and to provide a numeric concentration limit for these pollutants,
which would prevent situations where a different concentration of
covered pollutants is emitted from facility to facility or unit to
unit.
The EPA also proposed to remove the NO<INF>X</INF> emissions
averaging alternative provided in the EG.\101\ We determined that
owners or operators rarely use this emissions averaging alternative and
proposed that it is incompatible with the NO<INF>X</INF> emissions
standards established in the Good Neighbor Plan, which were considered
as part of the five-year review process as discussed in sections III.A
and IV.A of this preamble.
---------------------------------------------------------------------------

\101\ 40 CFR 60.33b(d)(1).
---------------------------------------------------------------------------

b. How did the proposed revisions to the alternative percent reduction
standards change for the large MWC source category?
After considering public comments and upon further review, the EPA
is not finalizing the proposed removal of the alternative percent
reduction standards allowed in the existing NSPS and EG. Instead, we
are finalizing recalculated alternative percent reduction standards
based on additional 1990-1995 removal efficiency data for the best
performing units used in the re-evaluated MACT standards for Hg, HCl
and SO<INF>2</INF>. The EPA used emission reduction data and a
predictive statistical interval, the lower predictive limit (LPL), to
calculate alternative standards to the concentration-based emission
limits for these three pollutants.\102\ The EPA received comments
supporting and opposing the removal of the alternative

[[Page 11823]]

percent reduction standards. Considering the comments, the EPA
recognizes that the alternative percent reduction standards provide
much-needed compliance flexibility considering the variable composition
of municipal solid waste and the air pollution controls available for
covered pollutants. Occasional slugs of high sulfur or chlorine-
containing waste materials may cause brief spikes in acid gas content
of the flue gas, to which acid gas scrubbing devices may not
immediately be able to respond. Similarly, a mercury-containing item in
the municipal waste stream could cause an unanticipated spike, which
the activated carbon adsorbent injection system may not immediately be
able to respond and which may cause noncompliance with a numeric flue
gas concentration limit, although the device is still achieving a high
level of Hg removal. Because large MWC owners and operators have
limited control over the contents of the waste combusted in their
units, this flexibility furthers the goal of leveling the playing field
for large MWCs. Without the percent reduction alternative, a large MWC
could have a set of air pollution controls identified as the BSER but,
due to the unexpected or unusual presence of a waste with a high
content of a covered pollutant or precursor to a covered pollutant, be
unable to comply with the numeric flue gas concentration limit through
no fault of their own. This means that even if two large MWCs have
identical administrative and engineering controls, one may be able to
demonstrate compliance with the standard and the other may not. That
does not represent a level playing field, and only potentially subjects
the compliance status of large MWCs to the whims of what the public
throws in municipal waste on any given day. The percent reduction
alternative standard provides for a more level playing field where two
large MWCs with the same administrative and engineering controls can
consistently achieve compliance regardless of the contents of the
municipal waste, which they cannot completely control.
---------------------------------------------------------------------------

\102\ See memorandum entitled MACT Floor Calculation for Large
Municipal Waste Combustor Units--Final Rule, available in the docket
for this rulemaking.
---------------------------------------------------------------------------

The EPA also recognizes, however, that the Agency relied heavily on
engineering judgement while developing the existing alternative percent
reduction standards rather than data demonstrating the performance of
the best performing sources. Therefore, as discussed above, the EPA has
recalculated these alternative standards based on emissions data using
LPL predictive statistics. The resulting alternative percent reduction
standards are generally similar to the existing standards but now
reflect a standard based on actual emissions performance data. For
example, the EG Hg and SO<INF>2</INF> alternative percent removal
standards remain unchanged. However, the EG HCl percent reduction
standard rises from 95% to 96%. Similarly, for the NSPS, the Hg percent
reduction standard is unchanged at 85%. However, the HCl standard rises
from 95% to 98%, while the SO<INF>2</INF> drops by a percentage point,
from 80% to 79%.
The EPA is not including the NO<INF>X</INF> emissions averaging
allowance in the final subpart WWWW EG although for different reasons
than those stated at proposal. We conclude that existing sources will
not need this allowance on two distinct factors. First, we are not
aware of any units that cannot meet the revised NO<INF>X</INF> MACT
floor limits without mass retrofits and additional controls. As a
result, there will be no large scale retrofit needs across the fleet of
large MWCs to meet the final NO<INF>X</INF> emission limits and less
burden on existing sources to accomplish additional NO<INF>X</INF>
emissions reductions and retrofits about which commenters expressed
concerns. Because we are finalizing the reevaluated NO<INF>X</INF> MACT
floor emission limits, the expected need to retrofit is limited in
scope and should not result in significant limited retrofit resource
availability or scheduling concerns that an averaging allowance would
help alleviate.
Second, an analysis of the air pollution controls installed at
large MWC facilities shows that almost all units are similarly equipped
at any given facility. For NO<INF>X</INF>, this means that, with very
limited exceptions, each unit at a facility employs the same
NO<INF>X</INF> control device (i.e., SCR, SNCR) or has a lower
NO<INF>X</INF>-generating design.\103\ As a result, the EPA does not
anticipate a need to average data from a better-controlled or
performing source at a facility with that from a source without a
similar control or at a lower performance to allow that lower-
performing unit to operate. Specific comments on this topic and
associated responses to the alternative percent reduction standards and
removal of the emissions averaging allowance are in the Comment
Response Document in the docket for this rulemaking.
---------------------------------------------------------------------------

\103\ The only two exceptions are facilities where the owner or
operator constructed a new large municipal waste combustor unit at a
later date, and the new unit was subject to 40 CFR 60 subpart Eb
NSPS, which does not contain an emissions averaging allowance.
---------------------------------------------------------------------------

3. Changes for Optional Continuous Monitoring
a. What did we propose with respect to optional continuous monitoring
for the large MWC source category?
The EPA proposed to incorporate updated performance specifications
for the optional use of a PM CEMS or Hg CEMS or the use of multi-metal,
HCl, PCDD/PCDF CEMS in place of stack tests into the large MWC
requirements. The proposed changes would update the 2006 final
amendments to the large MWC rules, which revised the PM and Hg
compliance testing requirements to allow the optional use of a PM CEMS
or Hg CEMS in place of stack testing and allow the optional use of
multi-metal, HCl, PCDD/PCDF CEMS in place of stack tests after
performance specifications for these CEMS are promulgated.\104\
---------------------------------------------------------------------------

\104\ 71 FR 27326 (May 10, 2006).
---------------------------------------------------------------------------

The EPA also requested comment on whether the use of CEMS for
compliance testing requires adopting alternative emission limits. We
noted that more recent combustion rulemakings have included 30-day
hourly rolling averages for pollutants measured with Hg CEMS (e.g.,
Mercury Air Toxics Standards, 40 CFR part 63, subpart UUUU) or other
optional CEMS (e.g., CISWI NSPS and EG, 40 CFR part 60, subparts CCCC
and DDDD). We also requested comment on whether the 30-day rolling
hourly average is appropriate to use in the large MWC source category.
b. How did the revisions to the optional continuous monitoring
provisions change for the large MWC source category?
The EPA is finalizing the proposed changes to continue to allow the
optional use of CEMS in place of stack testing after performance
specifications for the CEMS are promulgated and incorporate currently
available applicable performance specifications. This allows
flexibility for a facility to use CEMS for which performance
specifications do not yet exist through the use of site-specific
performance evaluation plans. Additionally, we are not finalizing 30-
day averaging times for any of the required CEMS pollutant monitoring
(CO, SO<INF>2</INF> and NO<INF>X</INF>). The EPA at this time has
insufficient information to assess the suitability and magnitude of a
potential 30-day rolling average, as the data consists solely of the
maximum four-hour or 24-hour average, recorded over the course of a
reporting year. The EPA received comments mainly supporting the

[[Page 11824]]

allowance of CEMS for additional pollutants as an option, but some
commenters urged the EPA to require monitoring using CEMS. Specific
comments and associated responses to the optional use of CEMS and a 30-
day hourly rolling average are in the Comment Response Document in the
docket for this rulemaking.
4. Changes To Streamline Regulatory Text Within the Large MWC EG and
NSPS
a. What did we propose with respect to streamlining regulatory text for
the large MWC source category?
The EPA proposed changes to the regulatory format of the large MWC
standards to be more accessible and easier to follow than the 1995
large MWC final rule. The proposed rule converted paragraph text
describing emission standards and performance testing requirements to
tables to facilitate easier implementation and understanding of the
requirements. The EPA added these new tables to the ends of the
subparts for these requirements, similar to the approach in other,
recent CAA section 129 rulemakings.
b. How did the proposed revisions to streamline regulatory text change
for the large MWC source category?
The EPA is finalizing changes to the regulatory format of the large
MWC standards as proposed, with additional revisions to convert the
text and tables to new subparts VVVV and WWWW, incorporate Federal
Plain Language Guidelines, and establish section-numbering increments
of five to allow or adequate numeric spacing to revise or add new
regulatory text sections if needed in the future. The EPA received no
substantive comments on streamlining the regulatory text.
5. Closing the 2007 Proposed Reconsideration of the Large MWC EG and
NSPS
a. What did we propose in connection with closing the 2007 proposed
reconsideration for the large MWC source category?
The EPA proposed to complete action on the March 20, 2007
reconsideration that the EPA had not finalized. In that 2007 notice, we
announced our reconsideration of three aspects of the 2007 final rule
based on stakeholder requests: operator stand-in provisions, data
requirements for continuous monitors, and the status of operating
parameters during the two weeks prior to Hg and PCDD/PCDF testing.\105\
We proposed that no changes to the 2007 final rule were warranted as a
result of the reconsideration.\106\ In the proposed rule for this
action, the EPA reiterated the issues raised and discussed in the 2007
notice, acknowledged that we received only one supportive comment on
these issues, and proposed to finalize the 2007 reconsideration, as
previously proposed, with no changes to those three aspects of the
rule, if the Agency received no adverse comments during the comment
period for this rulemaking.\107\
---------------------------------------------------------------------------

\105\ 72 FR 13016 (Mar. 20, 2007).
\106\ Id.
\107\ 89 FR 4257 (Jan. 23, 2024). As a miscellaneous and
superfluous observation, the EPA notes that the reconsideration
petition issue concerning the Pb standard, which the EPA did not
grant, is moot based on this final action to address the voluntary
remand of the MACT floors, which results in more stringent Pb
standards.
---------------------------------------------------------------------------

b. How did the proposed revisions change for the large MWC source
category?
The EPA is making no additional changes to the final rule as a
result of the proposed closing of the issues raised in the 2007
reconsideration, as recent comments received generally support closing
these issues. We received comments both supporting the operator stand-
in provisions as they exist and supporting revisions to the provisions
to shorten the timeframe that provisionally certified operators may
operate the MWC unit. Additionally, commenters supported not changing
the mass carbon feed rate operating parameter provisions for PCDD/PCDF
and Hg testing. Our response to these comments is in the Comment
Response Document in the docket for this rulemaking.
6. Updating Operator Training Examination Requirements
a. What did we propose with respect to updating operator training exam
requirements for the large MWC source category?
The EPA proposed to include and incorporate by reference the
updated QRO in the final rulemaking. The 1995 large MWC final rule
cited the 1994 version, QRO-1-1994. However, ASME released an updated
version in 2005, identified as QRO-1-2005, which the EPA proposed to
include in the regulatory text and incorporate by reference.
b. How did the proposed revisions change for the large MWC source
category?
The EPA is promulgating as proposed with no additional changes to
the final rule. We received one comment requesting increased training
requirements for MWC operators, supervisors, and personnel. Our
response to this comment is in the Comment Response Document in the
docket for this rulemaking. The reference to QRO-1-2005 has been added
to 40 CFR 60.17(g), 60.5865, and 60.6420.
7. Revisions to Title V Permitting Requirements for Air Curtain
Incinerators Burning Only Wood Waste, Clean Lumber, and Yard Waste
a. What did we propose in connection with title V permitting
requirements for air curtain incinerators for the large MWC source
category?
The EPA proposed to remove a title V permitting requirement in the
1995 large MWC final rule for air curtain incinerators that only burn
wood wastes, yard wastes, and clean lumber (and that comply with
applicable opacity limitations) and are not at a major source or
subject to title V for other reasons.\108\ The EPA noted in the
proposed rule that CAA section 129(e), which requires title V permits
for solid waste incineration units, does not apply to these ACI because
they are not solid waste incineration units, as defined in CAA section
129(g)(1)(C). The proposed rule explained that the EPA nevertheless
required title V permitting for these air curtain incinerators in
previous rulemakings for various reasons, primarily because we believed
that compliance with a title V permit was necessary to assure
compliance with the opacity requirements established for such
incinerators. However, we proposed to remove this requirement based on
feedback from several States indicating that the title V requirements
are unnecessarily burdensome and expensive for States to maintain and
based on data showing that air curtain incinerators that burn
exclusively wood waste, clean lumber, and yard waste are commonly at
facilities that would not otherwise require a title V operating permit.
---------------------------------------------------------------------------

\108\ 89 FR 4258 (Jan. 23, 2024).
---------------------------------------------------------------------------

b. How did the proposed revisions concerning title V permitting
requirements for air curtain incinerators change for the large MWC
source category?
The EPA received comments supporting and opposing the removal of
the title V permitting requirements for air curtain incinerators that
only burn wood waste, clean lumber, and yard waste; comply with opacity
limitations; and that are not at a major source or subject to title V
for other reasons. After

[[Page 11825]]

consideration of these comments and the exclusion of these ACI from the
title V permitting requirement in section 129(e) as they are not
``solid waste incineration units'' as defined in 129(g)(1)(C), we are
finalizing, as proposed, the removal of the title V permitting
requirements for these units. As noted in the proposed rule, to the
EPA's knowledge, no large MWC facility also operates an air curtain
incinerator that burns exclusively wood waste, clean lumber, and yard
waste. Our response to comments on the removal of this requirement is
in the Comment Response Document in the docket for this rulemaking.
8. Electronic Reporting
a. What did we propose in terms of electronic reporting for the large
MWC source category?
The EPA proposed that owners and operators of large MWC units
submit electronic copies of required performance test reports,
performance evaluation reports, semiannual compliance reports, annual
reports, and certain notifications through CDX using CEDRI. We proposed
that owners or operators must collect performance test results using
test methods that ERT supports, as listed on the ERT website at the
time of the test; submit theses in the format generated by the ERT or
an electronic file consistent with the XML schema on the ERT website;
and submit other performance test results in PDF using the attachment
module of the ERT.\109\ We also proposed that owners or operators must
submit performance evaluation results of CEMS measuring RATA pollutants
in the format generated by the ERT or an electronic file consistent
with the XML schema on the ERT website, and submit other performance
evaluation results in PDF using the attachment module of the ERT. The
proposed rule would require owners or operators to submit certain other
notifications as a PDF upload in CEDRI. For semiannual and annual
reports, the EPA proposed that owners and operators use an appropriate
spreadsheet template (provided in the docket for review) to submit
information to CEDRI.
---------------------------------------------------------------------------

\109\ See Electronic Reporting Tool (ERT): <a href="https://www.epa.gov/electronic-reporting-air-emissions/electronic-reporting-tool-ert">https://www.epa.gov/electronic-reporting-air-emissions/electronic-reporting-tool-ert</a>.
---------------------------------------------------------------------------

The EPA proposed two broad circumstances in which the Agency may
provide electronic reporting extensions: first, outages of CDX or CEDRI
that preclude an owner or operator from accessing the system and
submitting required reports, and second, force majeure events, defined
as events that will be or have been caused by circumstances beyond the
control of the affected facility, its contractors, or any entity
controlled by the affected facility that prevent an owner or operator
from complying with the requirement to submit a report
electronically.\110\
---------------------------------------------------------------------------

\110\ See 40 CFR 63.2 (definition of force majeure).
---------------------------------------------------------------------------

b. How did the proposed revisions for electronic reporting change for
the large MWC source category?
Commenters generally supported the proposed requirements for
electronic reporting. One commenter requested flexibility on the
effective dates for electronic reporting, and another commenter
suggested that the EPA require reporting of all large MWC CEMS data in
averaging times that an entity can compare to the standard. To address
this, the EPA has revised the regulatory text at 40 CFR 60.6090(c)(2)
and 60.6630(c)(2) to add the requirement that owners or operators
report all block averages during the reporting period as well as
identify the periods of warmup, startup, and shutdown during which they
collect all CEMS data and the large MWC is operating. We are not
changing the effective dates for electronic reporting in response to
comments received. Our complete responses to these comments are in the
Comment Response Document in the docket for this rulemaking.
9. Technical and Implementation Corrections
a. What did we propose in terms of technical and implementation
corrections for the large MWC source category?
The EPA proposed corrections and clarifications to the NSPS and EG
that the Agency and stakeholders identified during implementation of
the previous regulations, as follows:
1. Applicability and Delegation of Authority
<bullet> Adding 40 CFR 60.6300(d) and 60.5705 to clarify that large
MWC units subject to 40 CFR part 60, subpart WWWW are not subject to 40
CFR part 60, subpart Db. This makes the NSPS and EG consistent with 40
CFR part 60, subpart Db, which exempts large MWC units from that
subpart.
<bullet> Revising 40 CFR 60.6255 to clarify that the EPA
Administrator retains approval of certain exemption claims in 40 CFR
60.6305(a), (b), (c), (d), and (g); approval of major alternatives to
test methods and monitoring; approval of waivers of recordkeeping;
performance test and data reduction waivers; and approval of
alternatives to electronic reporting to the EPA and that the approval
authority does not transfer to a State upon delegation of authority to
that State to implement an approved State plan.
<bullet> Revising 40 CFR 60.5710 to clarify that the EPA
Administrator retains sole authority to issue the federally enforceable
11 tpd limit for exemptions in 40 CFR 60.5700(a) and the 30 percent
municipal waste limit for co-fired units in 40 CFR 60.5700b(g).
<bullet> Revising 40 CFR 60.5710(a)(4) to correct a typographical
error and clarify that the EPA Administrator retains sole authority to
review and approve demonstrations that establish the relationship
between carbon dioxide (not CO) and oxygen as part of initial and
annual performance tests.
2. Definitions
<bullet> Amending the definition of ``federally enforceable'' in 40
CFR 60.6145 to correct a cross-referencing error, i.e., to reference 40
CFR 51.165 and 51.166 instead of 40 CFR 51.18 and 51.24.
3. Performance Testing and Monitoring
<bullet> Revising 40 CFR 60.5960 and 60.5970(b) to correct an
oversight and clarify that the revised testing schedule (once per
calendar year but no less than nine months and no more than 15 months
following the previous test) also applies to fugitive ash and HCl
testing.
4. Reporting and Recordkeeping Requirements
<bullet> Revising 40 CFR 60.6255 to clarify that State plans are
due on March 10, 2027.
<bullet> Adding 40 CFR 60.6045(h)(i) to clarify that owners or
operators must record all data for continuous monitoring systems using
``local time'' for the location of the affected facility unless the
Administrator approves an alternative time system.
<bullet> Revising 40 CFR 60.6090(c) to require owners and operators
to additionally report the annual arithmetic average of all hourly
values recorded during operations for the reporting year.
b. How did the proposed technical and implementation corrections change
for the large MWC source category?
The EPA received minimal comments on these proposed revisions, and
is not making significant changes to the final rule from the proposed
clarifications and corrections. The EPA has converted the proposed
clarifications and corrections to text in the final rule at 40 CFR part
60, subparts VVVV and WWWW and updated citations and

[[Page 11826]]

cross-references accordingly. The comments received on these proposed
changes mainly focused on other suggestions for monitoring and testing
requirements of the rule. Our response to these comments is in the
Comment Response Document in the docket for this rulemaking.

V. Summary of Cost, Environmental and Economic Impacts, and Additional
Analyses Conducted

A. What are the affected facilities?

The large MWC source category comprises units with a capacity
greater than 250 tpd of MSW. The EPA estimates the current fleet of
large MWC units to include 152 units at 57 facilities nationwide. Of
these, 129 (85 percent) are mass-burn units, and the remaining are
refuse-derived fuel systems. Approximately 30 percent of currently
operating large MWCs are subject to 40 CFR part 60, subpart Eb (2006
NSPS limits), with the remaining subject to 40 CFR part 60, subparts Ea
(NSPS limits for units constructed after December 20, 1989, and on or
before September 20, 1994), or Cb (EG for units constructed before
September 20, 1994). The EPA estimates that there are 22 municipally
owned or operated facilities, with a total of 62 municipally owned or
operated large MWC units. As discussed in section III of this preamble,
the final rule creates new subparts VVVV (NSPS for facilities for which
construction is commenced after January 23, 2024) and WWWW (EG for
units constructed on or before January 23, 2024), which will replace
subparts Ea, Eb, and Cb, once effective. All units currently subject to
subparts Ea, Eb, and Cb will need to be in compliance with 40 CFR part
60, subpart WWWW not later than three years after the Administrator
approves the applicable State plan but not later than five years after
the EPA promulgates the guidelines, as required by CAA section
129(b)(2).

B. What are the air quality impacts?

The EPA estimates this final rule will result in 3,269 tpy
reduction in regulated pollutants from existing sources through
implementation of the final emission limits. The EPA estimated
emissions reductions for all units that would likely need add-on
controls, improvements to existing control devices, or increased carbon
or lime injection rates to meet a given limit.\111\ Because the EPA
assumes that good combustion practices are the most effective control
for CO, compared to add-on controls or control improvements, the Agency
assessed no additional control costs or associated emission reductions
for CO.\112\ For all other pollutants, the EPA assumed that units would
comply with emission limits by operating the control measure(s)
described in the large MWC cost memorandum.\113\ Table 7 of this
preamble presents these reductions.
---------------------------------------------------------------------------

\111\ See memorandum entitled Emission Reduction Estimates for
Existing Large MWCs Final Rule Amendments, Docket ID No. EPA-HQ-OAR-
2017-0183.
\112\ Further, the annual maximum data for the majority of
sources do not reflect actual performance. As noted in section IV.B
of this preamble, the EPA is finalizing significant changes to the
continuous monitoring reporting provisions so that we have access to
continuous data. Therefore, an assessment of any presumed emissions
reductions in comparison to the reevaluated MACT floor for CO is not
possible at this time.
\113\ See memorandum entitled Compliance Cost Analyses for Large
MWC Final Rule Amendments, Docket ID No. EPA-HQ-OAR-2017-0183.

Table 7--Estimated Annual Emissions Reductions for the Final Rule
------------------------------------------------------------------------
Reductions achieved
Pollutant \2\ Unit of measure through final rule
implementation
------------------------------------------------------------------------
Cd........................... ton/yr.......... 0.0024
Pb........................... ton/yr.......... 0.0409
PCDD/PCDF.................... g/yr............ 4.0
HCl.......................... ton/yr.......... 641
NOX.......................... ton/yr.......... 2,630
------------------------------------------
Total \1\................ ton/yr.......... 3,269
------------------------------------------------------------------------
\1\ Values have been rounded to three significant figures. Rows may not
appear to sum correctly due to rounding.
\2\ Hg or SO2 have no emission reductions.

Indirect or secondary air emissions can result from the increased
energy requirements associated with the operation of new control
devices (i.e., increased emissions of criteria pollutants from the
power plants supplying that additional electricity). The EPA expects
that existing units still operating electrostatic precipitators for
particulate control may need to retrofit with a fabric filter control
device, but we expect the difference in energy needs for each of these
devices to be minimal. Further, any improvements made to existing
fabric filters will not be significant enough to require a larger fan,
meaning that electricity consumption would remain unchanged. For
NO<INF>X</INF> control, most units already have SNCR, so further
control, if needed, could require retrofitting with ASNCR or
LNTM NO<INF>X</INF> technology. Owners or operators would
likely use existing SNCR equipment for these retrofit options, meaning
any additional power consumption requirements would be minimal. In the
rare case where a unit goes from no SNCR to SNCR, the unit's own
generating capabilities, rather than through fossil fuel combustion,
would supply the minimal amount of power required to pump reagent to
the furnace. We expect sources to further control Hg and PCDD/PCDF
through increased carbon injection for units that already have
activated carbon injection systems or by installing new activated
carbon injection systems.
We expect increases in power demand for existing systems and demand
for new systems to be minimal and met with a small fraction of the
power generation from the facility. Similarly, we expect power demand
increases for acid gas control systems to be minimal and met with power
that facilities are already generating. Sources typically control acid
gases with a dry sorbent injector scrubber or spray dryer absorber.
Additional control (i.e., increased sorbent injection rates in the
existing control device) would require only minimal increases in
sorbent conveying equipment power needs. If an owner or operator
determined a need for a retrofit to a CFBS to meet the standards for
acid gases, this retrofit could provide a small savings in sorbent
injection and power consumption needs. A CFBS is generally more

[[Page 11827]]

effective at acid gas control for the same amount of sorbent and at a
power consumption equal to or less than that of spray dryer absorbers.
As a result of these assessments, the reevaluated emission limits
for large MWCs are unlikely to have any consequential secondary air
impacts because the increase in energy requirements due to new control
measures is minimal, and power already being generated at the plant
would support what little additional energy may be required. For the
same reason, impacts on the overall nationwide energy requirements are
expected to be negligible.

C. What are the cost impacts?

We have estimated compliance costs for all existing units to add
the necessary controls to meet the final standards.\114\ We anticipate
an overall capital investment of approximately $90 million, with an
associated total annualized cost (including operating and maintenance
costs) of approximately $26 million (in 2024 dollars). Table 8 of this
preamble provides the cost breakdown by pollutant grouping and
regulatory option.
---------------------------------------------------------------------------

\114\ See memorandum entitled Compliance Cost Analyses for Large
MWC Final Rule Amendments, Docket ID No. EPA-HQ-OAR-2017-0183. Final
rule cost estimates in Table 8 reflect updates to cost inputs for
hydrated lime and landfill tipping fees received during the public
comment period.

Table 8--Compliance Costs of Final Rule
[2030-2049] \1\
----------------------------------------------------------------------------------------------------------------
Final rule estimate
------------------------------------------------
Pollutant grouping Total capital cost Total annualized cost ($/
($) yr) \1\
----------------------------------------------------------------------------------------------------------------
Cd, Pb......................................................... $19,000,000 $1,100,000
Dioxins/Furans (PCDD/PCDF)..................................... 0 0
HCl............................................................ 0 11,000,000
Nitrogen Oxides (NOX).......................................... 71,000,000 14,000,000
------------------------------------------------
Total control costs........................................ $90,000,000 $26,000,000
----------------------------------------------------------------------------------------------------------------
\1\ Includes operating and maintenance costs. We have annualized capital costs over 20 years at an interest rate
of 7.5 percent unless noted otherwise, except for particulate ca

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