Rule2024-09185
Supplemental Effluent Limitations Guidelines and Standards for the Steam Electric Power Generating Point Source Category
Primary source
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Published
May 9, 2024
Effective
July 8, 2024
Issuing agencies
Environmental Protection Agency
Abstract
The Environmental Protection Agency (EPA or the Agency) is finalizing a Clean Water Act regulation to revise the technology-based effluent limitations guidelines and standards (ELGs) for the steam electric power generating point source category applicable to flue gas desulfurization (FGD) wastewater, bottom ash (BA) transport water and legacy wastewater at existing sources, and combustion residual leachate (CRL) at new and existing sources. Last updated in 2015 and 2020, this regulation is estimated to cost an additional $536 million to $1.1 billion dollars annually in social costs and reduce pollutant discharges by an additional approximately 660 to 672 million pounds per year.
Full Text
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[Federal Register Volume 89, Number 91 (Thursday, May 9, 2024)]
[Rules and Regulations]
[Pages 40198-40306]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 2024-09185]
[[Page 40197]]
Vol. 89
Thursday,
No. 91
May 9, 2024
Part V
Environmental Protection Agency
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40 CFR Part 423
Supplemental Effluent Limitations Guidelines and Standards for the
Steam Electric Power Generating Point Source Category; Final Rule
Federal Register / Vol. 89, No. 91 / Thursday, May 9, 2024 / Rules
and Regulations
[[Page 40198]]
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ENVIRONMENTAL PROTECTION AGENCY
40 CFR Part 423
[EPA-HQ-OW-2009-0819; FRL-8794-02-OW]
RIN 2040-AG23
Supplemental Effluent Limitations Guidelines and Standards for
the Steam Electric Power Generating Point Source Category
AGENCY: Environmental Protection Agency (EPA).
ACTION: Final rule.
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SUMMARY: The Environmental Protection Agency (EPA or the Agency) is
finalizing a Clean Water Act regulation to revise the technology-based
effluent limitations guidelines and standards (ELGs) for the steam
electric power generating point source category applicable to flue gas
desulfurization (FGD) wastewater, bottom ash (BA) transport water and
legacy wastewater at existing sources, and combustion residual leachate
(CRL) at new and existing sources. Last updated in 2015 and 2020, this
regulation is estimated to cost an additional $536 million to $1.1
billion dollars annually in social costs and reduce pollutant
discharges by an additional approximately 660 to 672 million pounds per
year.
DATES: This final rule is effective on July 8, 2024. In accordance with
40 CFR part 23, this regulation shall be considered issued for purposes
of judicial review at 1 p.m. Eastern time on May 23, 2024. Under
section 509(b)(1) of the Clean Water Act (CWA), judicial review of this
regulation can be had only by filing a petition for review in the U.S.
Court of Appeals within 120 days after the regulation is considered
issued for purposes of judicial review. Under section 509(b)(2), the
requirements of this regulation may not be challenged later in civil or
criminal proceedings brought by EPA to enforce these requirements.
ADDRESSES: The EPA has established a docket for this action under
Docket ID No. EPA-HQ-OW-2009-0819. All documents in the docket are
listed on the <a href="https://www.regulations.gov">https://www.regulations.gov</a> website. Although listed in
the index, some information listed in the index is not publicly
available, e.g., confidential business information (CBI) or other
information whose disclosure is restricted by statute. Certain other
material, such as copyrighted material, is not placed on the internet
and will be publicly available only in hard copy form. Publicly
available docket materials are available electronically through <a href="https://www.regulations.gov">https://www.regulations.gov</a>.
FOR FURTHER INFORMATION CONTACT: For technical information, contact
Richard Benware, Engineering and Analysis Division, telephone: 202-566-
1369; email: <a href="/cdn-cgi/l/email-protection#781a1d160f190a1d560a111b10190a1c381d0819561f170e"><span class="__cf_email__" data-cfemail="a1c3c4cfd6c0d3c48fd3c8c2c9c0d3c5e1c4d1c08fc6ced7">[email protected]</span></a>. For economic information, contact
James Covington, Water Economics Center, telephone: 202-566-1034;
email: <a href="/cdn-cgi/l/email-protection#95f6fae3fcfbf2e1fafbbbfff4f8f0e6d5f0e5f4bbf2fae3"><span class="__cf_email__" data-cfemail="5f3c30293631382b303171353e323a2c1f3a2f3e71383029">[email protected]</span></a>.
SUPPLEMENTARY INFORMATION:
Preamble Acronyms and Abbreviations. The EPA uses multiple acronyms
and terms in this preamble. To ease the reading of this preamble and
for reference purposes, the EPA defines terms and abbreviations used in
appendix A (although the list of abbreviations in the appendix is not
exhaustive).
Supporting Documentation. The rule is supported by several
documents, including the following:
<bullet> Technical Development Document for the Final Supplemental
Effluent Limitations Guidelines and Standards for the Steam Electric
Power Generating Point Source Category (TDD), Document No. 821R24004.
This report summarizes the technical and engineering analyses
supporting the rule. The TDD presents the EPA's updated analyses
supporting the revisions to FGD wastewater, BA transport water, CRL,
and legacy wastewater. The TDD includes additional data that has been
collected since the publication of the 2015 and 2020 rules, updates to
the industry (e.g., retirements, updates to wastewater handling), cost
methodologies, pollutant removal estimates, non-water quality
environmental impacts associated with updated FGD and BA methodologies,
and calculations for the effluent limitations. In addition to the TDD,
the Technical Development Document for the Effluent Limitations
Guidelines and Standards for the Steam Electric Power Generating Point
Source Category (2015 TDD, Document No. EPA-821-R-15-007) and the
Supplemental Technical Development Document for Revisions to the
Effluent Limitations Guidelines and Standards for the Steam Electric
Power Generating Point Source Category (2020 Supplemental TDD, Document
No. EPA-821-R-20-001) provide a more complete summary of the EPA's data
collection, description of the industry, and underlying analyses
supporting the 2015 and 2020 rules.
<bullet> Environmental Assessment for the Final Supplemental
Effluent Limitations Guidelines and Standards for the Steam Electric
Power Generating Point Source Category (EA), Document No. 821R24005.
This report summarizes the potential environmental and human health
impacts estimated to result from implementation of the revisions to the
2015 and 2020 rules.
<bullet> Benefit and Cost Analysis for the Final Supplemental
Effluent Limitations Guidelines and Standards for the Steam Electric
Power Generating Point Source Category (BCA), Document No. 821R24006.
This report summarizes the societal benefits and costs estimated to
result from implementation of the revisions to the 2015 and 2020 rules.
<bullet> Regulatory Impact Analysis for the Final Supplemental
Effluent Limitations Guidelines and Standards for the Steam Electric
Power Generating Point Source Category (RIA), Document No. 821R24007.
This report presents a profile of the steam electric power generating
industry, a summary of estimated costs and impacts associated with the
revisions to the 2015 and 2020 rules, and an assessment of the
potential impacts on employment and small businesses.
<bullet> Environmental Justice Analysis for the Final Supplemental
Effluent Limitations Guidelines and Standards for the Steam Electric
Power Generating Point Source Category (EJA), Document No. 821R24008.
This report presents a profile of the communities and populations
potentially impacted by this rule, an analysis of the distribution of
impacts in the baseline scenario and with the revisions, and a summary
of inputs from potentially impacted communities that the EPA met with
prior to publishing the proposed rulemaking.
<bullet> Docket Index for the Supplemental Effluent Limitations
Guidelines and Standards for the Steam Electric Power Generating Point
Source Category. This document provides a list of additional memoranda,
references, and other information the EPA relied on for the final
revisions to the ELGs.
Organization of this Document. The information in this preamble is
organized as follows:
Table of Contents
I. Executive Summary
A. Purpose of Rule
II. Public Participation
III. General Information
A. Does this action apply to me?
B. What action is the EPA taking?
C. What is EPA's authority for taking this action?
D. What are the monetized incremental costs and benefits of this
action?
IV. Background
A. Clean Water Act
B. Relevant Effluent Guidelines
C. 2015 Steam Electric Power Generation Point Source Category
Rule
D. 2020 Steam Electric Reconsideration Rule and Recent
Developments
[[Page 40199]]
E. Other Ongoing EPA Rules Impacting the Steam Electric Sector
V. Steam Electric Power Generating Industry Description
A. General Description of Industry
B. Current Market Conditions and Drivers in the Electricity
Generation Sector
C. Control and Treatment Technologies
VI. Data Collection Since the 2020 Rule
A. Information from the Electric Utility Industry
B. Notices of Planned Participation
C. Information from Technology Vendors and Engineering,
Procurement, and Construction Firms
D. Other Data Sources
VII. Final Regulation
A. Description of the Options
B. Rationale for the Final Rule
C. Subcategories
D. Additional Rationale for the Proposed PSES and PSNS
E. Availability Timing of New Requirements
F. Economic Achievability
G. Non-Water Quality Environmental Impacts
H. Impacts on Residential Electricity Prices and Communities
with Environmental Justice Concerns
VIII. Costs, Economic Achievability, and Other Economic Impacts
A. Plant-Specific and Industry Total Costs
B. Social Costs
C. Economic Impacts
IX. Pollutant Loadings
A. FGD Wastewater
B. BA Transport Water
C. CRL
D. Legacy Wastewater
E. Summary of Incremental Changes of Pollutant Loadings from the
Final Rule
X. Non-Water Quality Environmental Impacts
A. Energy Requirements
B. Air Pollution
C. Solid Waste Generation and Beneficial Use
D. Changes in Water Use
XI. Environmental Assessment
A. Introduction
B. Updates to the Environmental Assessment Methodology
C. Outputs from the Environmental Assessment
XII. Benefits Analysis
A. Categories of Benefits Analyzed
B. Quantification and Monetization of Benefits
C. Total Monetized Benefits
D. Additional Benefits
XIII. Environmental Justice Impacts
A. Literature Review
B. Proximity Analysis
C. Community Outreach
D. Distribution of Risks
E. Distribution of Benefits and Costs
XIV. Regulatory Implementation
A. Continued Implementation of Existing Limitations and
Standards
B. Implementation of New Limitations and Standards
C. Reporting and Recordkeeping Requirements
D. Site-Specific Water Quality-Based Effluent Limitations
E. Severability
XV. Statutory and Executive Order Reviews
A. Executive Order 12866: Regulatory Planning and Review and
Executive Order 14094: Modernizing Regulatory Review
B. Paperwork Reduction Act (PRA)
C. Regulatory Flexibility Act (RFA)
D. Unfunded Mandates Reform Act (UMRA)
E. Executive Order 13132: Federalism
F. Executive Order 13175: Consultation and Coordination with
Indian Tribal Governments
G. Executive Order 13045: Protection of Children from
Environmental Health Risks and Safety Risks
H. Executive Order 13211: Actions That Significantly Affect
Energy Supply, Distribution, or Use
I. National Technology Transfer and Advancement Act
J. Executive Order 12898: Federal Actions to Address
Environmental Justice in Minority Populations and Low-Income
Populations and Executive Order 14096: Revitalizing Our Nation's
Commitment to Environmental Justice for All
K. Congressional Review Act (CRA)
Appendix A to the Preamble: Definitions, Acronyms, and Abbreviations
Used in This Preamble
I. Executive Summary
A. Purpose of Rule
The EPA is promulgating this final supplemental rule to update
requirements that apply to wastewater discharges from steam electric
power plants, particularly coal-fired power plants. In 2015, the EPA
set the first Federal limitations on the levels of toxic metals in
several of the largest sources of wastewater that can be discharged
from power plants after last updating these regulations in 1982 (80
Federal Register (FR) 67838; November 3, 2015) (hereinafter the ``2015
rule''). On an annual basis, the 2015 rule was projected to reduce the
amount of toxic metals, nutrients, and other pollutants that steam
electric power plants are allowed to discharge by 1.4 billion pounds
and reduce water withdrawal by 57 billion gallons. This rule was
reconsidered in 2020 and modified in part due to changing dynamics in
the power sector (85 FR 64650; October 13, 2020) (hereinafter the
``2020 rule''). Steam electric power plants are increasingly aging and
less competitive sources of electric power in many portions of the
United States.
Steam electric power plants, coal-fired power plants in particular,
are subject to several environmental regulations designed to control
(and in some cases eliminate) air, water, and land pollution over time.
This rule, the Steam Electric Power Generating Effluent Limitations
Guidelines and Standards--or steam electric ELGs--applies to the subset
of the electric power industry where ``generation of electricity is the
predominant source of revenue or principal reason for operation, and
whose generation of electricity results primarily from a process
utilizing fossil-type fuel (e.g., coal, oil, gas), fuel derived from
fossil fuel (e.g., petroleum coke, synthesis gas), or nuclear fuel in
conjunction with a thermal cycle employing the steam-water system as
the thermodynamic medium'' (40 Code of Federal Regulations (CFR)
423.10). The 2015 rule addressed discharges from FGD wastewater, fly
ash (FA) transport water, BA transport water, flue gas mercury control
(FGMC) wastewater, gasification wastewater, CRL, legacy wastewater, and
nonchemical metal cleaning wastes. The 2020 rule modified the 2015
requirements for FGD wastewater and BA transport water for existing
sources only. The 2015 limitations for CRL from existing sources and
legacy wastewater were vacated by the United States (U.S.) Court of
Appeals for the Fifth Circuit in Southwestern Electric Power Co., et
al. v. EPA, 920 F.3d 999 (5th Cir. 2019).
In the years since the EPA revised the steam electric ELGs in 2015
and 2020, new information has become available, which the EPA
considered in finalizing this supplemental rule. For example, pilot
testing and full-scale use of various, better performing treatment
technologies have continued to develop, along with more data and
information about their performance. The final supplemental rule
updates requirements for discharges from two wastestreams addressed in
the 2020 rule: BA transport water and FGD wastewater at existing
sources. The final supplemental rule also replaces the court-vacated
limitations for CRL (except for CRL discharges in one subcategory) and
a subcategory of legacy wastewater. Finally, for the remaining CRL and
legacy wastewaters, this rule finalizes a site-specific approach to
developing technology-based limitations based on the permitting
authorities' best professional judgment (BPJ), an option discussed by
the Court in Southwestern Electric Power Co. v. EPA.
B. Summary of Final Rule
For existing sources that discharge directly to surface water, with
the exception of the subcategories discussed below, the final rule
establishes the following effluent limitations based on Best Available
Technology Economically Achievable (BAT):
<bullet> A zero-discharge limitation for all pollutants in FGD
wastewater, BA transport water, and CRL.
[[Page 40200]]
<bullet> Numeric (nonzero) discharge limitations for mercury and
arsenic in unmanaged CRL \1\ and for legacy wastewater discharged from
surface impoundments during the closure process if those surface
impoundments have not commenced closure under the Coal Combustion
Residuals (CCR) regulations as of the effective date of this rule.
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\1\ As discussed in section VII.C.5 of this document, the EPA is
defining unmanaged CRL in this rule to mean CRL which either: (1)
the permitting authority determines are the functional equivalent of
a direct discharge to waters of the United States (WOTUS) through
groundwater or (2) CRL that has leached from a waste management unit
into the subsurface and mixed with groundwater prior to being
captured and pumped to the surface for discharge directly to a
WOTUS.
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The final rule eliminates the separate, 2020 rule's less stringent
BAT requirements for two subcategories: high-flow facilities and low-
utilization electric generating units (LUEGUs), except to the extent
they apply to one new permanent cessation of coal combustion
subcategory. The final rule leaves in place the existing subcategories
for oil-fired and small (50 megawatts (MW) or less) electric generating
units (EGUs) established in the 2015 rule. The final rule also leaves
in place the existing subcategory for EGUs permanently ceasing the
combustion of coal by 2028, which was established in the 2020 rule and
amended in a 2023 direct final rule by extending the date for filing a
Notice of Planned Participation (NOPP). See 88 FR 18440 (March 29,
2023). Lastly, the final rule creates a new subcategory for EGUs
permanently ceasing coal combustion by 2034. For both the existing and
new subcategories referenced immediately above, the EPA is finalizing
additional reporting and recordkeeping requirements and zero-discharge
limitations applicable after EGUs cease coal combustion, as well as
procedural requirements for affected facilities to demonstrate
permanent cessation of coal combustion or that permanent retirement
will occur.
As stated above, the rule eliminates the 2020 rule subcategories
for high flow and low utilization, except to the extent they apply to
EGUs in the new permanent cessation of coal combustion by 2034
subcategory. The elimination of the 2020 rule's subcategories will
affect the one known high-flow facility (the Tennessee Valley Authority
(TVA) Cumberland Fossil Plant) that has indicated it is planning to
close and the two known facilities with LUEGUs (GSP Merrimack LLC and
Indiana Municipal Power Agency (IMPA) Whitewater Valley Station), one
of which is also expected to close. For EGUs ceasing coal combustion by
2034, the final rule retains the 2020 rule requirements for FGD
wastewater and BA transport water and the pre-2015 BPJ-based BAT
requirements for CRL rather than requiring the new, more stringent
zero-discharge requirements for these wastestreams. After the permanent
cessation of coal combustion, however, EGUs in this subcategory must
meet limitations on arsenic and mercury based on chemical precipitation
for CRL.
Where BAT limitations in this final rule are more stringent than
previously established Best Practicable Control Technology Currently
Available (BPT) and BAT limitations, any new limitations for direct
dischargers do not apply until a date determined by the permitting
authority that is as soon as possible on or after July 8, 2024, but no
later than December 31, 2029.
For indirect discharges (i.e., discharges to publicly owned
treatment works (POTWs)), the final rule establishes pretreatment
standards for existing sources that are the same as the BAT limitations
except where limitations are for total suspended solids (TSS), a
pollutant that does not pass through POTWs. Pretreatment standards are
directly enforceable and apply May 9, 2027.
While the EPA is not aware of any planned new sources that would be
subject to the requirements of this final supplement rule, this action
sets new source performance standards and pretreatment standards for
discharges of CRL from new sources that are equivalent to the new BAT
limitations--namely, zero discharge.
C. Summary of Costs and Benefits
The EPA estimates that the final rule will cost $536 million to
$1.1 billion per year in social costs and result in $3.2 billion per
year in monetized benefits using a 2 percent discount rate.\2\
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\2\ The EPA estimated the annualized value of future benefits
and costs using a discount rate of 2 percent, following current
Office of Management and Budget (OMB) guidance in Circular A-4 (OMB,
2023). In appendix B of the BCA, the EPA also provides results of
analyses performed using 3 percent and 7 percent discount rates to
allow comparison of the final rule costs and benefits with those
estimated at proposal, which followed the guidance applicable at the
time the prior analysis was conducted (OMB, 2003).
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The EPA's analysis reflects the Agency's understanding of the
actions steam electric power plants are expected to take to meet the
limitations and standards in the final rule, including the
implementation of additional treatment technologies to reduce pollutant
discharges. The EPA based its analysis on a modeled baseline that
reflects the full implementation of the 2020 rule, the expected effects
of announced retirements and fuel conversions, and the anticipated
impacts of relevant final rules affecting the power sector. Not all
costs and benefits can be fully quantified and monetized. While some
health benefits and willingness to pay (WTP) for water quality
improvements have been quantified and monetized, those estimates may
not fully capture all important water-quality-related benefits.
Furthermore, the EPA anticipates the final rule would generate
important additional benefits that the Agency was only able to analyze
qualitatively (e.g., improved habitat conditions for plants,
invertebrates, fish, amphibians, and the wildlife that prey on aquatic
organisms).
For additional information on costs and benefits, see sections VIII
and XII of this preamble, respectively.
II. Public Participation
During the 60-day public comment period on the 2023 proposed
supplemental rule (88 FR 18824, March 29, 2023) (from March 29, 2023,
to May 30, 2023), the EPA received more than 22,000 public comment
submissions from private citizens, industry representatives, technology
vendors, government entities, environmental groups, and trade
associations. The EPA also hosted two online public hearings during the
public comment period--one on April 20, 2023, and one on April 25,
2023. These hearings had a combined total of 196 attendees, 46 of whom
registered to provide comment on the proposed rule. Available documents
from each public hearing include the presentations given by the EPA and
two transcripts (document control number (DCN) SE10469, DCN SE10469A1,
DCN SE10470 and DCN SE10470A1).
III. General Information
A. Does this action apply to me?
Entities potentially regulated by any final rule following this
action include the following:
[[Page 40201]]
------------------------------------------------------------------------
North American
Industry
Category Example of regulated Classification
entity System (NAICS)
Code
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Industry....................... Electric Power 22111
Generation Facilities--
Electric Power
Generation.
Electric Power 221112
Generation Facilities--
Fossil Fuel Electric
Power Generation.
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This section is not intended to be exhaustive, but rather provides
a guide regarding entities likely to be regulated by this final rule.
Other types of entities that do not meet the above criteria could also
be regulated. To determine whether a specific facility is regulated by
this final rule, carefully examine the applicability criteria listed in
40 CFR 423.10 and the definitions in 40 CFR 423.11. If you still have
questions regarding the applicability of this final rule to a
particular entity, consult the person listed for technical information
in the preceding FOR FURTHER INFORMATION CONTACT section.
B. What action is the EPA taking?
The Agency is revising certain BAT ELGs for existing sources in the
steam electric power generating point source category that apply to FGD
wastewater, BA transport water, CRL, and legacy wastewater.
C. What is EPA's authority for taking this action?
The EPA is finalizing this rule under the authority of sections
301, 304, 306, 307, 308, 402, and 501 of the CWA, 33 United States Code
(U.S.C.) 1311, 1314, 1316, 1317, 1318, 1342, and 1361.
D. What are the monetized incremental costs and benefits of this
action?
This final rule is estimated to have social costs of $536 million
to $1.1 billion per year and result in $3.2 billion in benefits using a
two percent discount rate.\3\
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\3\ See note 2.
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IV. Background
A. Clean Water Act
Congress passed the Federal Water Pollution Control Act Amendments
of 1972, also known as the CWA, to ``restore and maintain the chemical,
physical, and biological integrity of the Nation's waters.'' 33 U.S.C.
1251(a). The CWA establishes a comprehensive program for protecting our
nation's waters. Among its core provisions, the CWA prohibits the
discharge of pollutants from a point source to waters of the United
States (WOTUS), except as authorized under the CWA. Under section 402
of the CWA, discharges may be authorized through a National Pollutant
Discharge Elimination System (NPDES) permit. The CWA also authorizes
the EPA to establish nationally applicable, technology-based ELGs for
discharges from different categories of point sources, such as
industrial, commercial, and public sources.
Furthermore, the CWA authorizes the EPA to promulgate nationally
applicable pretreatment standards that restrict pollutant discharges
from facilities that discharge wastewater to WOTUS indirectly through
sewers flowing to POTWs, as outlined in CWA sections 307(b) and (c), 33
U.S.C. 1317(b) and (c). The EPA establishes national pretreatment
standards for those pollutants in wastewater from indirect dischargers
that may pass through, interfere with, or are otherwise incompatible
with POTW operations. Pretreatment standards are designed to ensure
that wastewaters from direct and indirect industrial dischargers are
subject to similar levels of treatment. See CWA section 301(b), 33
U.S.C. 1311(b); Chem. Mfrs. Ass'n v. NRDC, 470 U.S. 116, 119 (1985);
Envtl. Def. Fund v. Costle, 636 F.2d 1229, 1235 n.15 (D.C. Cir. 1980);
Reynolds Metals Co. v. EPA, 760 F.2d 549, 553 (4th Cir. 1985); Chem.
Mfrs. Ass'n v. EPA, 870 F.2d 177, 249 (5th Cir. 1989). In addition,
POTWs are required to implement local treatment limitations applicable
to their industrial indirect dischargers to satisfy any local
requirements. See 40 CFR 403.5.
Direct dischargers (i.e., those discharging directly from a point
source to surface waters rather than through POTWs) must comply with
effluent limitations in NPDES permits. Discharges that flow through
groundwater before reaching surface waters must also comply with
effluent limitations in NPDES permits if those discharges are the
``functional equivalent'' of a direct discharge from a point source to
a WOTUS. County of Maui v. Hawaii Wildlife Fund, 590 U.S. 165 (2020).
Indirect dischargers, who discharge through POTWs, must comply with
pretreatment standards. Technology-based effluent limitations in NPDES
permits are derived from ELGs (CWA sections 301 and 304, 33 U.S.C. 1311
and 1314) and new source performance standards (CWA section 306, 33
U.S.C. 1316) promulgated by the EPA, or based on BPJ where the EPA has
not promulgated an applicable effluent guideline or new source
performance standard. CWA section 402(a)(1)(B), 33 U.S.C.
1342(a)(1)(B); 40 CFR 125.3(c). Additional limitations based on water
quality standards are also required to be included in the permit in
certain circumstances. CWA section 301(b)(1)(C), 33 U.S.C.
1311(b)(1)(C); 40 CFR 122.44(d). The EPA establishes ELGs by regulation
for categories of point source dischargers, and these ELGs are based on
the degree of control that can be achieved using various levels of
pollution control technology.
The EPA promulgates national ELGs for major industrial categories
for three classes of pollutants: (1) conventional pollutants (i.e.,
TSS, oil and grease, biochemical oxygen demand (BOD<INF>5</INF>), fecal
coliform, and pH), as outlined in CWA section 304(a)(4) and 40 CFR
401.16; (2) toxic pollutants (e.g., toxic metals such as arsenic,
mercury, selenium, and chromium; toxic organic pollutants such as
benzene, benzo-a-pyrene, phenol, and naphthalene), as outlined in
section 307(a) of the Act, 40 CFR 401.15 and 40 CFR part 423, appendix
A; and (3) nonconventional pollutants, which are those pollutants that
are not categorized as conventional or toxic (e.g., ammonia-N,
phosphorus, total dissolved solids (TDS)).
B. Relevant Effluent Guidelines
The EPA develops effluent guidelines that are technology-based
regulations for a category of dischargers. The EPA bases these
regulations on the performance of control and treatment technologies.
The legislative history of CWA section 304(b), which is the heart of
the effluent guidelines program, describes the need to press toward
higher levels of control through research and development of new
processes, modifications, replacement of obsolete plants and processes,
and other improvements in technology, while also accounting for the
cost of controls. Legislative history and case law support that the EPA
need
[[Page 40202]]
not consider water quality impacts on individual water bodies as the
guidelines are developed; see Statement of Senator Muskie (October 4,
1972), reprinted in Legislative History of the Water Pollution Control
Act Amendments of 1972, at 170. (U.S. Senate, Committee on Public
Works, Serial No. 93-1, January 1973); see also Southwestern Elec.
Power Co. v. EPA, 920 F.3d at 1005 (``The Administrator must require
industry, regardless of a discharge's effect on water quality, to
employ defined levels of technology to meet effluent limitations.'')
(citations and internal quotations omitted).
There are many technology-based effluent limitations (TBELs) that
may apply to a discharger under the CWA: four types of standards
applicable to direct dischargers, two types of standards applicable to
indirect dischargers, and a default site-specific approach. The TBELs
relevant to this rulemaking are described in detail below.
1. Best Practicable Control Technology Currently Available
Traditionally, the EPA defines Best Practicable Control Technology
(BPT) effluent limitations based on the average of the best
performances of facilities within the industry, grouped to reflect
various ages, sizes, processes, or other common characteristics. See
Southwestern Elec. Power Co. v. EPA, 920 F3d at 1025. The EPA may
promulgate BPT effluent limitations for conventional, toxic, and
nonconventional pollutants. In specifying BPT, the EPA looks at several
factors. The EPA considers the cost of achieving effluent reductions in
relation to the effluent reduction benefits. The Agency also considers
the age of equipment and facilities, the processes employed,
engineering aspects of the control technologies, any required process
changes, non-water quality environmental impacts (including energy
requirements), and such other factors as the Administrator deems
appropriate. CWA section 304(b)(1)(B), 33 U.S.C. 1314(b)(1)(B). If,
however, existing performance is uniformly inadequate, the EPA may
establish limitations based on higher levels of control than what is
currently in place in an industrial category, when based on an agency
determination that the technology is available in another category or
subcategory and can be practicably applied.
2. Best Available Technology Economically Achievable
BAT represents the second level of stringency for controlling
direct discharge of toxic and nonconventional pollutants. Courts have
referred to this as the CWA's ``gold standard'' for controlling
discharges from existing sources. Southwestern Elec. Power Co. v. EPA,
920 F.3d at 1003; see also Kennecott v. EPA, 780 F.2d 445, 448 (4th
Cir. 1985) (``The BAT standard reflects the intention of Congress to
use the latest scientific research and technology in setting effluent
limits, pushing industries toward the goal of zero discharge as quickly
as possible.''). In general, BAT represents the best available,
economically achievable performance of facilities in the industrial
subcategory or category. As the statutory phrase intends, the EPA
considers the technological availability and the economic achievability
when determining what level of control represents BAT. CWA section
301(b)(2)(A), 33 U.S.C. 1311(b)(2)(A). Other statutory factors that the
EPA considers in assessing BAT are the cost of achieving BAT effluent
reductions, the age of equipment and facilities involved, the process
employed, potential process changes, and non-water quality
environmental impacts, including energy requirements, and such other
factors as the Administrator deems appropriate. CWA section
304(b)(2)(B), 33 U.S.C. 1314(b)(2)(B). The Agency retains considerable
discretion in assigning the weight to be accorded these factors.
Weyerhaeuser Co. v. Costle, 590 F.2d 1011, 1045 (D.C. Cir. 1978). The
EPA usually determines economic achievability based on the effect the
cost of compliance with BAT limitations has on overall industry and
subcategory financial conditions.
BAT reflects the highest performance in the industry and may
reflect a higher level of performance than is currently being achieved
based on technology transferred from a different subcategory or
category, bench scale or pilot plant studies, or foreign plants.
Southwestern Elec. Power Co. v. EPA, 920 F.3d at 1006; Chem. Mfrs.
Ass'n v. EPA, 870 F.2d at 226; Nat. Res. Def. Council v. EPA, 863 F.2d
1420, 1426 (9th Cir. 1988); American Paper Inst. v. Train, 543 F.2d
328, 353 (D.C. Cir. 1976); American Frozen Food Inst. v. Train, 539
F.2d 107, 132 (D.C. Cir. 1976). BAT may be based upon process changes
or internal controls, even when these technologies are not common
industry practice. See American Frozen Foods, 539 F.2d at 132, 140;
Reynolds Metals Co. v. EPA, 760 F.2d at 562; California & Hawaiian
Sugar Co. v. EPA, 553 F.2d 280, 285-88 (2nd Cir. 1977). ``In setting
BAT, EPA uses not the average plant, but the optimally operating plant,
the pilot plant which acts as a beacon to show what is possible.''
Kennecott v. EPA, 780 F.2d at 448 (citing A Legislative History of the
Water Pollution Control Act Amendments of 1972, 93d Cong., 1st Sess.
(Comm. Print 1973), at 798). As recently reiterated by the U.S. Court
of Appeals for the Fifth Circuit, ``Under our precedent, a
technological process can be deemed available for BAT purposes even if
it is not in use at all, or if it is used in unrelated industries. Such
an outcome is consistent with Congress'[s] intent to push pollution
control technology.'' Southwestern Elec. Power Co. v. EPA, 920 F.3d at
1031 (citation and internal quotations omitted); see also Am. Petroleum
Inst. v. EPA, 858 F.2d 261, 265 (5th Cir. 1988).
3. New Source Performance Standards
New Source Performance Standards (NSPS) reflect effluent reductions
that are achievable based on the Best Available Demonstrated Control
Technology (BADCT). Owners of new facilities have the opportunity to
install the best and most efficient production processes and wastewater
treatment technologies. As a result, NSPS should represent the most
stringent controls attainable through the application of the BADCT for
all pollutants (that is, conventional, nonconventional, and toxic
pollutants). In establishing NSPS, the EPA is directed to take into
consideration the cost of achieving the effluent reduction and any non-
water quality environmental impacts and energy requirements. CWA
section 306(b)(1)(B), 33 U.S.C. 1316(b)(1)(B).
4. Pretreatment Standards for Existing Sources
Section 307(b), 33 U.S.C. 1317(b), of the CWA calls for the EPA to
issue pretreatment standards for discharges of pollutants to POTWs.
Pretreatment standards for existing sources (PSES) are designed to
prevent the discharge of pollutants that pass through, interfere with,
or are otherwise incompatible with the operation of POTWs. Categorical
pretreatment standards are technology-based and are analogous to BPT
and BAT ELGs; thus, the Agency typically considers the same factors in
promulgating PSES as it considers in promulgating BAT. The General
Pretreatment Regulations, which set forth the framework for the
implementation of categorical pretreatment standards, are found at 40
CFR part 403. These regulations establish pretreatment standards that
apply to all non-domestic dischargers. See 52 FR 1586 (January 14,
1987).
[[Page 40203]]
5. Pretreatment Standards for New Sources
Section 307(c), 33 U.S.C. 1317(c), of the Act calls for the EPA to
promulgate Pretreatment Standards for New Sources (PSNS). Such
pretreatment standards must prevent the discharge of any pollutant into
a POTW that may interfere with, pass through, or may otherwise be
incompatible with the POTW. The EPA promulgates PSNS based on BADCT for
new sources. New indirect dischargers have the opportunity to
incorporate into their facilities the best available demonstrated
technologies. The Agency typically considers the same factors in
promulgating PSNS as it considers in promulgating NSPS.
6. Best Professional Judgment
CWA section 301 and its implementing regulation at 40 CFR 125.3(a)
indicate that technology-based treatment requirements under section
301(b) of the CWA represent the minimum level of control that must be
imposed in an NPDES permit. Where EPA-promulgated effluent guidelines
are not applicable to a non-POTW discharge, or where such EPA-
promulgated guidelines have been vacated by a court, such treatment
requirements are established on a case-by-case basis using the permit
writer's BPJ. Case-by-case TBELs are developed pursuant to CWA section
402(a)(1), which authorizes the EPA Administrator to issue a permit
that will meet either: all applicable requirements developed under the
authority of other sections of the CWA (e.g., technology-based
treatment standards, water quality standards, ocean discharge criteria)
or, before taking the necessary implementing actions related to those
requirements, ``such conditions as the Administrator determines are
necessary to carry out the provisions of this Act.'' The regulation at
40 CFR 125.3(c)(2) cites this section of the CWA, stating that
technology-based treatment requirements may be imposed in a permit ``on
a case-by-case basis under section 402(a)(1) of the Act, to the extent
that EPA-promulgated effluent limitations are inapplicable.''
Furthermore, Sec. 125.3(c)(3) indicates, ``[w]here promulgated
effluent limitations guidelines only apply to certain aspects of the
discharger's operation, or to certain pollutants, other aspects or
activities are subject to regulation on a case-by-case basis in order
to carry out the provisions of the Act.'' The factors considered by the
permit writer are the same as those that the EPA considers in
establishing technology-based effluent limitations. See 40 CFR
125.3(d)(1) through (3).
C. 2015 Steam Electric Power Generation Point Source Category Rule
1. 2015 Rule Requirements
On November 3, 2015, the EPA promulgated a rule revising the
regulations for the Steam Electric Power Generating point source
category, 40 CFR part 423. 80 FR 67838, November 3, 2015. The rule set
the first Federal limitations on the levels of toxic pollutants (e.g.,
arsenic) and nutrients (e.g., nitrogen) that can be discharged in the
steam electric power generating industry's largest sources of
wastewater, based on technology improvements in the steam electric
power industry over the preceding three decades. Before the 2015 rule,
regulations for the industry were last updated in 1982 and, for the
industry's wastestreams with the largest pollutant loadings, contained
only limitations on TSS and oil and grease.
Over those 30 years, new technologies for generating electric power
and the widespread implementation of air pollution controls had altered
existing wastewater streams or created new wastewater streams at many
steam electric facilities, particularly coal-fired facilities.
Discharges of these wastestreams include arsenic, lead, mercury,
selenium, chromium, and cadmium. Once in the environment, many of these
toxic pollutants can remain there for years and continue to cause
adverse impacts.
The 2015 rule addressed effluent limitations and standards for
multiple wastestreams generated by new and existing steam electric
facilities: BA transport water, CRL, FGD wastewater, FGMC wastewater,
FA transport water, gasification wastewater, and legacy wastewater.\4\
The rule required most steam electric facilities to comply with the
effluent limitations ``as soon as possible'' after November 1, 2018,
and no later than December 31, 2023. NPDES permitting authorities
established particular applicability date(s) within that range for each
facility (except for indirect dischargers) at the time they reissued
the facility's NPDES permit.
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\4\ These wastestreams are defined in appendix A to this
preamble.
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The 2015 rule was projected to reduce the amount of metals the CWA
defines as toxic pollutants, nutrients, and other pollutants that steam
electric facilities are allowed to discharge by 1.4 billion pounds per
year and reduce water withdrawal by 57 billion gallons. At the time,
the EPA estimated annual compliance costs for the final rule to be $480
million (in 2013 dollars, discounted at 3 percent) and estimated annual
benefits associated with the rule to be $451 to $566 million (in 2013
dollars, discounted at 3 percent).
2. Vacatur of Limitations Applicable to CRL and Legacy Wastewater
Seven petitions for review of the 2015 rule were filed in various
circuit courts by the electric utility industry, environmental groups,
and drinking water utilities. These petitions were consolidated in the
U.S. Court of Appeals for the Fifth Circuit, Southwestern Electric
Power Co. v. EPA, Case No. 15-60821 (5th Cir.). On March 24, 2017, the
Utility Water Act Group submitted to the EPA an administrative petition
for reconsideration of the 2015 rule. On April 5, 2017, the Small
Business Administration (SBA) submitted an administrative petition for
reconsideration of the 2015 rule.
On August 11, 2017, then EPA Administrator Scott Pruitt announced
his decision to conduct a rulemaking to potentially revise the new,
more stringent BAT effluent limitations and pretreatment standards for
existing sources in the 2015 rule that apply to FGD wastewater and BA
transport water. The Fifth Circuit subsequently granted the EPA's
request to sever and hold in abeyance petitioners' claims related to
those limitations and standards, and those claims are still in
abeyance. With respect to the remaining claims related to limitations
applicable to legacy wastewater and CRL, the Fifth Circuit issued a
decision on April 12, 2019, vacating those limitations as arbitrary and
capricious under the Administrative Procedure Act and unlawful under
the CWA, respectively. Southwestern Elec. Power Co. v. EPA, 920 F.3d
999. In particular, the Court rejected the EPA's BAT limitations for
each wastestream set equal to previously promulgated BPT limitations
based on surface impoundments. In the case of legacy wastewater, the
Court held that the EPA's record on surface impoundments did not
support BAT limitations based on surface impoundments. Id. at 1015. In
the case of CRL, the Court held that the EPA's setting of BAT
limitations equal to BPT limitations was an impermissible conflation of
the two standards, which are supposed to be progressively more
stringent, and that the EPA's rationale was not authorized by the
statutory factors for determining BAT. Id. at 1026. After the Court's
decision, the EPA announced its plans to address the vacated
limitations in a later action after the 2020 rule.
[[Page 40204]]
In September 2017 (82 FR 43494), using notice-and-comment
procedures, the EPA finalized a rule postponing the earliest compliance
dates for the more stringent BAT effluent limitations and PSES for FGD
wastewater and BA transport water in the 2015 rule, from November 1,
2018, to November 1, 2020 (``postponement rule''). The EPA also
withdrew a prior action it had taken to stay parts of the 2015 rule
pursuant to section 705 of the Administrative Procedure Act, 5 U.S.C.
705. The postponement rule received multiple legal challenges, but the
courts did not sustain any of them.\5\
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\5\ See Center for Biological Diversity v. EPA, No. 18-cv-00050
(D. Ariz. filed January 20, 2018); see also Clean Water Action. v.
EPA, No. 18-60079 (5th Cir.). On October 29, 2018, the District of
Arizona case was dismissed upon the EPA's motion to dismiss for lack
of jurisdiction, and on August 28, 2019, the Fifth Circuit denied
the petition for review of the postponement rule.
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D. 2020 Steam Electric Reconsideration Rule and Recent Developments
1. 2020 Rule Requirements
On October 13, 2020, the EPA promulgated the Steam Electric
Reconsideration Rule (85 FR 64650). The 2020 rule revised requirements
for FGD wastewater and BA transport water applicable to existing
sources. Specifically, the 2020 rule made four changes to the 2015
rule. First, the rule changed the technology basis for control of FGD
wastewater and BA transport water. For FGD wastewater, the technology
basis was changed from chemical precipitation plus high-hydraulic-
residence-time biological reduction to chemical precipitation plus low-
hydraulic-residence-time biological reduction. This change in the
technology basis resulted in less stringent selenium limitations but
more stringent mercury and nitrogen limitations. For BA transport
water, the technology basis was changed from dry-handling or closed-
loop systems to high-recycle-rate systems, allowing for a site-specific
purge not to exceed 10 percent of the BA transport system's volume.
This change in technology resulted in less stringent limitations for
all pollutants in BA transport water. Second, the 2020 rule revised the
technology basis for the voluntary incentives program (VIP) for FGD
wastewater from vapor compression evaporation to chemical precipitation
plus membrane filtration. This change in the technology basis resulted
in less stringent limitations for most pollutants but added new
limitations for bromide and nitrogen. Third, the 2020 rule created
three new subcategories for high-flow facilities, LUEGUs, and EGUs
permanently ceasing coal combustion by 2028. These subcategories were
subject to less stringent limitations: high-flow facilities were
subject to FGD wastewater limitations based on chemical precipitation;
LUEGUs were subject to FGD wastewater limitations based on chemical
precipitation and BA transport water limitations based on surface
impoundments and a best management practice (BMP) plan; and EGUs
permanently ceasing coal combustion by 2028 were subject to FGD
wastewater and BA transport water limitations based on surface
impoundments. Finally, the 2020 rule required most steam electric
facilities to comply with the revised effluent limitations ``as soon as
possible'' after October 13, 2021, and no later than December 31,
2025.\6\ NPDES permitting authorities established the particular
applicability date(s) of the new limitations within that range for each
facility (except for indirect dischargers) at the time they reissued
the facility's NPDES permit.
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\6\ The 2015 rule's VIP compliance date was revised to December
31, 2028, in the 2020 rule.
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2. Fourth Circuit Court of Appeals Litigation
Two petitions for review of the 2020 rule were timely filed by
environmental group petitioners and consolidated in the U.S. Court of
Appeals for the Fourth Circuit on November 19, 2020. Appalachian
Voices, et al. v. EPA, No. 20-2187 (4th Cir.). An industry trade group
and certain energy companies moved to intervene in the litigation,
which the Court granted on December 3, 2020. On April 8, 2022, the
Court granted the EPA's motion and placed the case into abeyance
pending the completion of the current rulemaking.
3. Executive Order 13990 and Announcement of Supplemental Rule
On January 20, 2021, President Biden issued Executive Order 13990:
Protecting Public Health and the Environment and Restoring Science to
Tackle the Climate Crisis. 86 FR 7037. Executive Order 13990 directed
Federal agencies to immediately review and, as appropriate and
consistent with applicable law, take action to address the promulgation
of Federal regulations and other actions during the previous four years
that conflict with the national objectives of protecting public health
and the environment.
On July 26, 2021, the EPA announced a new rulemaking to strengthen
certain wastewater pollution discharge limitations for coal-fired power
plants that use steam to generate electricity (86 FR 41801, August 3,
2021). The EPA later clarified that, as part of its new rulemaking, it
would be reconsidering all aspects of the 2020 rule. The EPA undertook
an evidence-based, science-based review of the 2020 rule under
Executive Order 13990, finding that there are opportunities to
strengthen certain wastewater pollution discharge limitations. For
example, the EPA discussed how treatment systems using membranes have
advanced since the 2020 rule's promulgation and continue to rapidly
advance as an effective option for treating a wide variety of
industrial pollution, including pollution from steam electric power
plants. In the announcement, the EPA also clarified that, until a new
rule is promulgated, part 423 will continue to be implemented and
enforced to achieve needed pollutant reductions.\7\
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\7\ This includes both the 2020 rule and portions of the 2015
rule which were not revised or vacated.
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4. Preliminary Effluent Guidelines Plan 15
In September 2021, the EPA issued Preliminary Effluent Guidelines
Program Plan 15.\8\ This document discussed the annual review of ELGs,
rulemakings for new and existing industrial point source categories,
and any new or existing sources receiving further analyses. Here, in
the context of the EPA's ongoing steam electric ELG rulemaking, EPA
noted relevant wastestreams including pointing out that the 2015 rule
limitations for CRL and legacy wastewater had been vacated and remanded
to the Agency. For further discussion of the vacatur and remand of the
2015 limitations applicable to CRL and legacy wastewater, see section
IV.D of this preamble.
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\8\ Available online at: <a href="http://www.epa.gov/system/files/documents/2021-09/ow-prelim-elg-plan-15_508.pdf">www.epa.gov/system/files/documents/2021-09/ow-prelim-elg-plan-15_508.pdf</a>.
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E. Other Ongoing EPA Rules Impacting the Steam Electric Sector
The EPA has recently proposed or finalized several other rules to
protect the nation's air, land, and water from pollution resulting from
coal-fired power plants. The EPA has primarily considered these other
rules to support this final rulemaking in two ways. First, when
appropriate, the EPA has included the impacts of final rules in the
baseline of its analyses. Second, the EPA has designed this final rule
to harmonize compliance dates, subcategories, and other aspects of
these rules to the extent possible and appropriate under different
statutory schemes. The following sections summarize the solid waste and
[[Page 40205]]
air rules that are most directly relevant to the electric power sector.
1. Coal Combustion Residuals Disposal Rule
On April 17, 2015, the EPA promulgated the Disposal of Coal
Combustion Residuals from Electric Utilities final rule (2015 CCR rule)
(80 FR 21302). This rule finalized national regulations to provide a
comprehensive set of requirements for the safe disposal of CCR,
commonly referred to as coal ash, from steam electric power plants. The
final 2015 CCR rule was the culmination of extensive study on the
effects of coal ash on the environment and public health. The rule
established technical requirements for CCR landfills and surface
impoundments under subtitle D of the Resource Conservation and Recovery
Act (RCRA), the Nation's primary law for regulating solid waste.
These regulations established requirements for the management and
disposal of coal ash, including requirements designed to prevent
leaking of contaminants into groundwater, blowing of contaminants into
the air as dust, and the catastrophic failure of coal ash surface
impoundments. The 2015 CCR rule also set recordkeeping and reporting
requirements, as well as requirements for each plant to establish and
post specific information to a publicly accessible website. The rule
also established requirements to distinguish the beneficial use of CCR
from disposal.
As a result of the D.C. Circuit Court decisions in Utility Solid
Waste Activities Group v. EPA, 901 F.3d 414 (D.C. Cir. 2018) (``USWAG
decision'' or ``USWAG''), and Waterkeeper Alliance Inc. et al. v. EPA,
No. 18-1289 (D.C. Cir. filed March 13, 2019), the Administrator signed
two rules: A Holistic Approach to Closure Part A: Deadline to Initiate
Closure and Enhancing Public Access to Information (CCR Part A rule)
(85 FR 53516, August 28, 2020) on July 29, 2020, and A Holistic
Approach to Closure Part B: Alternate Liner Demonstration (CCR Part B
rule) (85 FR 72506, December 14, 2020) on October 15, 2020. The EPA
finalized five amendments to the 2015 CCR rule which are relevant to
the management of the wastewaters covered by this ELG because these
wastewaters have historically been co-managed with CCR in the same
surface impoundments. First, the CCR Part A rule established a new
deadline of April 11, 2021, for all unlined surface impoundments in
which CCR are managed (``CCR surface impoundments''), as well as CCR
surface impoundments that failed the location restriction for placement
above the uppermost aquifer, to stop receiving waste and begin closure
or retrofitting. The EPA established this date after evaluating the
steps that owners and operators need to take for CCR surface
impoundments to stop receiving waste and begin closure, and the
timeframes needed for implementation. (This did not affect the ability
of plants to install new, composite-lined CCR surface impoundments.)
Second, the Part A rule established procedures for plants to obtain
approval from the EPA for additional time to develop alternative
disposal capacity to manage their wastestreams (both CCR and non-CCR)
before they must stop receiving waste and begin closing their CCR
surface impoundments. Third, the Part A rule changed the classification
of compacted-soil-lined and clay-lined surface impoundments from lined
to unlined. Fourth, the Part B rule finalized procedures potentially
allowing a limited number of facilities to demonstrate to the EPA that,
based on groundwater data and the design of a particular surface
impoundment, the unit ensures there is no reasonable probability of
adverse effects to human health and the environment. Should the EPA
approve such a submission, these CCR surface impoundments would be
allowed to continue to operate.
As explained in the 2015 and 2020 ELG rules, the ELGs and CCR rules
may affect the same EGU or activity at a plant. Therefore, when the EPA
finalized the ELG and CCR rules in 2015, and revisions to both rules in
2020, the Agency coordinated the ELG and CCR rules to minimize the
complexity of implementing engineering, financial, and permitting
activities. Likewise, the EPA considered the interaction of the two
rules during the development of this final rule. The EPA's analytic
baseline includes the final requirements of these rules using the most
recent data provided under the CCR rule reporting and recordkeeping
requirements. This is further described in Supplemental TDD, section 3.
For more information on the CCR Part A and Part B rules, including
information about their ongoing implementation, visit <a href="http://www.epa.gov/coalash/coal-ash-rule">www.epa.gov/coalash/coal-ash-rule</a>.
Concurrently with the final ELG, in a separate rulemaking, the EPA
is also finalizing regulatory requirements for inactive CCR surface
impoundments at inactive utilities (``legacy CCR surface impoundment''
or ``legacy impoundment'') (FR 2024-09157 (EPA-HQ-OLEM-2020-0107; FRL-
7814-04-OLEM)). This action is being taken in response to the August
21, 2018, opinion by the U.S. Court of Appeals for the District of
Columbia Circuit in the USWAG decision that vacated and remanded the
provision exempting legacy impoundments from the CCR regulations. This
action includes adding a definition for legacy CCR surface impoundments
and other terms relevant to this rulemaking. It also requires that
legacy CCR surface impoundments comply with certain existing CCR
regulations with tailored compliance deadlines.
The EPA is also establishing requirements to address the risks from
currently exempt solid waste management that involves the direct
placement of CCR on the land. The EPA is extending a subset of the
existing requirements in 40 CFR part 257, subpart D, to CCR surface
impoundments and landfills that closed prior to the effective date of
the 2015 CCR rule, inactive CCR landfills, and other areas where CCR is
managed directly on the land. In this action, the EPA refers to these
as CCR management units, or CCRMU. This rule will apply to all existing
CCR facilities and all inactive facilities with legacy CCR surface
impoundments subject to this final rule.
Finally, the EPA is making a number of technical corrections to the
existing regulations, such as correcting certain citations and
harmonizing definitions. For further information on the CCR
regulations, including information about the CCR Part A and Part B
rules' ongoing implementation, visit <a href="http://www.epa.gov/coalash/coal-ash-rule">www.epa.gov/coalash/coal-ash-rule</a>.
2. Air Pollution Rules and Implementation
The EPA is taking several actions to regulate a variety of
conventional, hazardous, and greenhouse gas (GHG) air pollutants,
including actions to regulate the same steam electric power plants
subject to part 423. In light of these ongoing actions, the EPA has
worked to consider appropriate flexibilities in this ELG rule to
provide certainty to the regulated community while ensuring the
statutory objectives of each program are achieved. Furthermore, to the
extent that these actions have been published before this rule's
signature and are already impacting steam electric power plant
operations, the EPA has accounted for these changed operations in its
Integrated Planning Model (IPM) modeling discussed in section VIII of
this preamble.
[[Page 40206]]
a. The Revised Cross State Air Pollution Rule Update and the Good
Neighbor Plan for the 2015 Ozone National Ambient Air Quality Standards
On June 5, 2023, the EPA promulgated its final Good Neighbor Plan,
which secures significant reductions in ozone-forming emissions of
nitrogen oxides (NO<INF>X</INF>) from power plants and industrial
facilities. 88 FR 36654. The Good Neighbor Plan ensures that 23 states
meet the Clean Air Act's (CAA's) ``Good Neighbor'' requirements by
reducing pollution that significantly contributes to problems attaining
and maintaining EPA's health-based air quality standard for ground-
level ozone (or ``smog''), known as the 2015 Ozone National Ambient Air
Quality Standards (NAAQS), in downwind states. Further information on
this action is available on the EPA's website.\9\
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\9\ See <a href="https://www.epa.gov/csapr/good-neighbor-plan-2015-ozone-naaqs">https://www.epa.gov/csapr/good-neighbor-plan-2015-ozone-naaqs</a>.
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As of September 21, 2023, the Good Neighbor Plan's ``Group 3''
ozone-season NO<INF>X</INF> control program for power plants is being
implemented in: Illinois, Indiana, Maryland, Michigan, New Jersey, New
York, Ohio, Pennsylvania, Virginia, and Wisconsin. Pursuant to court
orders staying the Agency's State Implementation Plan disapproval
action in the following States, the EPA is not currently implementing
the Good Neighbor Plan ``Group 3'' ozone-season NO<INF>X</INF> control
program for power plants in: Alabama, Arkansas, Kentucky, Louisiana,
Minnesota, Mississippi, Missouri, Nevada, Oklahoma, Texas, Utah, and
West Virginia.\10\
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\10\ Further information on EPA's response to the stay orders
can be found online at: <a href="https://www.epa.gov/Cross-State-Air-Pollution/epa-response-judicial-stay-orders">https://www.epa.gov/Cross-State-Air-Pollution/epa-response-judicial-stay-orders</a>.
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On January 16, 2024, the EPA signed a proposal to partially approve
and partially disapprove State Implementation Plan submittals
addressing interstate transport for the 2015 ozone NAAQS from Arizona,
Iowa, Kansas, New Mexico, and Tennessee and proposed to include these
States in the Good Neighbor Plan beginning in 2025 (89 FR 12666,
February 16, 2024).
On April 30, 2021, the EPA published the final Revised Cross-State
Air Pollution Rule (CSAPR) Update (86 FR 23054), which resolved 21
states' good neighbor obligations for the 2008 ozone NAAQS, following
the remand of the 2016 CSAPR Update (81 FR 74504, October 26, 2016) in
Wisconsin v. EPA, 938 F.3d 308 (D.C. Cir. 2019). Together, these two
rules establish the Group 2 and Group 3 market-based emissions trading
programs for 22 states in the eastern United States for emissions of
NO<INF>X</INF> from fossil fuel-fired EGUs during the summer ozone
season.
b. Clean Air Act section 111 Rule
Concurrently with the final ELG, the EPA is finalizing the repeal
of the Affordable Clean Energy Rule, establishing Best System of
Emissions Reduction (BSER) determinations and emission guidelines for
existing fossil fuel-fired EGUs, and establishing BSER determinations
and accompanying standards of performance for GHG emissions from new
and reconstructed fossil fuel-fired stationary combustion turbines and
modified fossil fuel-fired EGUs. Specifically, for coal-fired EGUs, the
EPA is establishing final standards based on carbon capture and
storage/sequestration with 90 percent capture with a compliance date of
January 1, 2032 (FR 2024-09233 (EPA-HQ-OAR-2023-0072; FRL-8536-01-
OAR)). For coal-fired EGUs retiring by January 1, 2039, the EPA is
establishing final standards based on 40 percent natural gas co-firing
with a compliance date of January 1, 2030.
While four subcategories for coal-fired EGUs were proposed, the EPA
is finalizing just the two subcategories for coal-fired EGUs as
described in the preceding paragraph. Consistent with 40 CFR 60.24a(e)
and the Agency's explanation in the proposal, states have the ability
to consider, inter alia, a particular source's remaining useful life
when applying a standard of performance to that source.\11\
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\11\ See 88 FR 33240 (May 23, 2023) (invoking RULOF based on a
particular coal-fired EGU's remaining useful life ``is not
prohibited under these emission guidelines'').
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In addition, the EPA is creating an option for states to provide
for a compliance date extension for existing sources of up to one year
under certain circumstances for sources that are installing control
technologies to comply with their standards of performance. States may
also provide, by inclusion in their state plans, a reliability
assurance mechanism of up to one year that under limited circumstances
would allow existing EGUs that had planned to cease operating by a
certain date to temporarily remain available to support reliability.
Any extensions exceeding 1-year must be addressed through a state plan
revision. Further information about the CAA section 111 rule is
available online at <a href="https://www.epa.gov/stationary-sources-air-pollution/greenhouse-gas-standards-and-guidelines-fossil-fuel-fired-power">https://www.epa.gov/stationary-sources-air-pollution/greenhouse-gas-standards-and-guidelines-fossil-fuel-fired-power</a>.
c. Mercury and Air Toxics Standards Rule
On March 6, 2023 (88 FR 13956), the EPA published a final rule
which reaffirmed that it remains appropriate and necessary to regulate
hazardous air pollutants (HAP), including mercury, from power plants
after considering cost. This action revoked a 2020 finding that it was
not appropriate and necessary to regulate coal- and oil-fired power
plants under CAA section 112, which covers toxic air pollutants. The
EPA reviewed the 2020 finding and considered updated information on
both the public health burden associated with HAP emissions from coal-
and oil-fired power plants, as well as the costs associated with
reducing those emissions under the Mercury and Air Toxics Standards
(MATS). After weighing the public risks these emissions pose to all
Americans (and particularly exposed and sensitive populations) against
the costs of reducing this harmful pollution, the EPA concluded that it
remains appropriate and necessary to regulate these emissions. This
action ensures that coal- and oil-fired power plants continue to
control emissions of hazardous air pollution and that the Agency
properly interprets the CAA to protect the public from hazardous air
emissions.
Concurrently with the final ELG, the EPA is finalizing an update to
the National Emission Standards for Hazardous Air Pollutants for Coal-
and Oil-Fired Electric Utility Steam Generating Units (EGUs), commonly
known as the Mercury and Air Toxics Standards (MATS) for power plants,
to reflect recent developments in control technologies and the
performance of these plants (FR 2024-0918 (EPA-HQ-OAR-2018-0794; FRL-
6716.3-02-OAR)). This final rule includes an important set of
improvements and updates to MATS and also fulfills the EPA's
responsibility under the Clean Air Act to periodically re-evaluate its
standards in light of advancements in pollution control technologies to
determine whether revisions are necessary. The improvements consist of:
<bullet> Further limiting the emission of non-mercury HAP metals
from existing coal-fired power plants by significantly reducing the
emission standard for filterable particulate matter (fPM), which is
designed to control non-mercury HAP metals. The EPA is finalizing a
two-thirds reduction in the fPM standard; \12\
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\12\ Also, the EPA is finalizing the removal of the low-emitting
EGU provisions for fPM and non-mercury HAP metals.
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[[Page 40207]]
<bullet> Tightening the emission limit for mercury for existing
lignite-fired power plants by 70 percent; \13\
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\13\ This level aligns with the mercury standard that other
coal-fired power plants have been achieving under the current MATS.
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<bullet> Strengthening emissions monitoring and compliance by
requiring coal-and oil-fired EGUs to comply with the fPM standard using
PM continuous emission monitoring systems (CEMS); \14\
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\14\ PM CEMS provide regulators, the public, and facility owners
or operators with cost-effective, accurate, and continuous emission
measurements. This real-time, quality-assured feedback can lead to
improved control device and power plant operation, which will reduce
air pollutant emissions and exposure for local communities.
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<bullet> Revising the startup requirements in MATS to assure better
emissions performance during startup.
Additional information on the final MATS is available on the EPA's
website.\15\
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\15\ See <a href="https://www.epa.gov/stationary-sources-air-pollution/mercury-and-air-toxics-standards">https://www.epa.gov/stationary-sources-air-pollution/mercury-and-air-toxics-standards</a>.
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d. National Ambient Air Quality Standards Rules for Particulate Matter
On February 7, 2024, the EPA Administrator signed a final rule
strengthening the National Ambient Air Quality Standards for
Particulate Matter (PM NAAQS) to protect millions of Americans from
harmful and costly health impacts, such as heart attacks and premature
death (89 FR 16202, March 6, 2024). Particle or soot pollution is one
of the most dangerous forms of air pollution, and an extensive body of
science links it to a range of serious and in some cases deadly
illnesses. The EPA set the level of the primary (health-based) annual
particulate matter (PM<INF>2.5</INF>) standard at 9.0 micrograms per
cubic meter to provide increased public health protection, consistent
with the available health science. The EPA did not change the current
primary and secondary (welfare-based) 24-hour PM<INF>2.5</INF>
standards, the secondary annual PM<INF>2.5</INF> standard, and the
primary and secondary PM<INF>10</INF> standards. The EPA also revised
the Air Quality Index to improve public communications about the risks
from PM<INF>2.5</INF> exposures and made changes to the monitoring
network to enhance protection of air quality in communities
overburdened by air pollution. More information about this action is
available on the EPA's website.\16\
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\16\ See <a href="https://www.epa.gov/pm-pollution/national-ambient-air-quality-standards-naaqs-pm">https://www.epa.gov/pm-pollution/national-ambient-air-quality-standards-naaqs-pm</a>.
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V. Steam Electric Power Generating Industry Description
A. General Description of Industry
For each previous regulatory action--the 2013 proposed rule (78 FR
34432, June 7, 2013), the 2015 final rule, the 2019 proposed rule (84
FR 64620, November 22, 2019), the 2020 final rule, and the 2023
proposed rule--the EPA provided general descriptions of the steam
electric power generating industry. The Agency has continued to collect
information and update this industry profile. The previous descriptions
reflected the known information about the universe of steam electric
power plants and incorporated final environmental regulations
applicable at that time. For this rule, as described in the
Supplemental TDD, section 3, the EPA has revised its description of the
steam electric power generating industry (and its supporting analyses)
to incorporate major changes such as additional retirements, fuel
conversions, ash handling conversions, wastewater treatment updates,
and updated information on capacity utilization.\17\ The analyses
supporting this rule use an updated baseline that incorporates these
changes in the industry and include the 2015 and 2020 rules'
limitations for FGD wastewater, BA transport water, CRL, and legacy
wastewater. The analyses then compare the effect of the new rule's
requirements to this baseline.
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\17\ The data presented in the general description continue to
reflect some conditions existing in 2009.The 2010 steam electric
industry survey remains the EPA's best available source of
information for characterizing operations across the industry in
cases where the EPA has not received newer information.
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As described in the Regulatory Impact Analysis, of the 858 steam
electric power plants in the country identified by the EPA, only those
coal-fired power plants that discharge FGD wastewater, BA transport
water, CRL, legacy wastewater and/or unmanaged CRL may incur compliance
costs under this rule. The EPA estimates that 141 to 170 such plants
may incur compliance costs under this rule, depending on the scenario
used to model the occurrence of unmanaged CRL costs. See section
VII.C.5 of this preamble for more information regarding subcategory for
discharges of unmanaged CRL. See the EPA's memorandum, Changes to
Industry Profile for Coal-Fired Generating Units for the Steam Electric
Effluent Guidelines Final Rule (DCN SE11618), for more information
about plant retirements, fuel conversions, ash handling conversions,
wastewater treatment updates, and updated information on capacity
utilization.
B. Current Market Conditions and Drivers in the Electricity Generation
Sector
1. Inflation Reduction Act Implementation
On August 16, 2022, President Biden signed into law the Inflation
Reduction Act (IRA). The IRA marks the most significant action Congress
has taken on clean energy and climate change in the nation's history.
The IRA provides tax credits, financing programs, and other incentives,
some of which are administered by the EPA, that will accelerate the
transition to forms of energy that produce little or no GHG emissions
and other water and air pollutants. As such, it includes many
provisions that will affect the steam electric power generating
industry, causing both direct effects through changes in the production
of electricity and indirect effects on electricity demand and changes
to fuel markets.
In September 2023, the EPA published a report on the effect of the
IRA on the electricity sector and on the economy in general.\18\ The
report found that the IRA would lead to emission reductions from the
electric power sector of 49 to 83 percent below 2005 levels in 2030.
The associated shifts from fossil fuel generation would also lead to
reductions in water and air pollution from the sector. The study also
found that the IRA would lower economy-wide CO<INF>2</INF> emissions,
including emissions from electricity generation and use, by 35 to 43
percent below 2005 levels in 2030. Across the end-use sectors, the
study found that buildings exhibit the greatest reductions from 2005
levels of direct plus indirect CO<INF>2</INF> emissions from
electricity, followed by industry and transportation. Though it focuses
on changes in climate-forcing emissions (in part attributable to the
models it uses), the study also implies important changes in the
emissions of other pollutants throughout the economy. The EPA used IPM
to evaluate the impacts of the final ELG relative to a baseline that
reflects impacts from other relevant policies and environmental
regulations that affect the power sector, including the IRA and other
on-the-books Federal and state rules (see section VIII.C.2 of this
preamble for more information).
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\18\ U.S. EPA (Environmental Protection Agency). 2023.
Electricity Sector Emissions Impacts of the Inflation Reduction Act:
Assessment of Projected CO<INF>2</INF> Emission Reductions from
Changes in Electricity Generation and Use. U EPA 430-R-23-004.
Available online at: <a href="https://www.epa.gov/inflation-reduction-act/electric-sector-emissions-impacts-inflation-reduction-act">https://www.epa.gov/inflation-reduction-act/electric-sector-emissions-impacts-inflation-reduction-act</a>.
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[[Page 40208]]
2. Recent Developments in Ensuring Electric Reliability and Resource
Adequacy
The nature and components of the bulk power sector have been
evolving away from older and less efficient legacy fossil generation
(mostly coal-fired power plants) towards more decentralized, renewable
assets and flexible gas-fired generation. Stakeholders have raised
concerns that centralized, dispatchable power plants are coming offline
faster than new generation can replace the reliability attributes
associated with them. However, a combination of technology innovation,
revised market signals from the Regional Transmission Organizations
(RTOs) and Independent System Operators (ISOs), and reforms recently
completed and underway by Federal Energy Regulatory Commission (FERC)
are collectively poised to address current reliability challenges
associated with the transition along with expected higher load growth
and the increasing frequency of extreme weather events. EPA has
continued to learn and engage on reliability issues, particularly as
part of the Agency's implementation of the Joint Memorandum on
Interagency Communication and Consultation on Electric Reliability.\19\
As part of this process, EPA has engaged in regular meetings with
Department of Energy (DOE), North American Electric Reliability
Corporation (NERC), FERC, and the various ISOs/RTOs.
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\19\ Available online at: <a href="https://www.epa.gov/power-sector/electric-reliability-mou">https://www.epa.gov/power-sector/electric-reliability-mou</a>.
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FERC, NERC, RTOs, and ISOs are already taking steps to ensure
reliability during this period of asset evolution. Among FERC's actions
to help address reliability is Order 2023, or ``Improvements to
Generator Interconnection Procedures,'' which will help expedite
interconnections for new assets waiting to connect to the grid. This is
a very important development to ensure future resource adequacy because
interconnection wait times for new energy assets entering energy
markets have increased, which is stifling the ability of replacement
generation to connect to the grid. FERC's final action on extreme cold
weather preparedness will support the new peak demand hours, which have
migrated to winter months. New reliability standards issued for
inverter-based resources ``will help ensure reliability of the grid by
accommodating the rapid integration of new power generation
technologies, known as inverter-based resources (IBRs), that include
solar photovoltaic, wind, fuel cell and battery storage resources. . .
.'' \20\ FERC has also undertaken various transmission-related efforts,
from inter-regional transmission capacity efforts to reconductoring and
dynamic line rating, that would help bolster reliability by increasing
the transmission capacity of existing lines and creating incentives for
new, inter-regional transmission. Increasing transmission capacity can
enhance reliability by increasing the amount of generation that can
access the grid to help meet demand.
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\20\ For further information about FERC actions to address IBRs,
see <a href="https://www.ferc.gov/news-events/news/ferc-moves-protect-grid-transition-clean-energy-resources">https://www.ferc.gov/news-events/news/ferc-moves-protect-grid-transition-clean-energy-resources</a>.
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Furthermore, there are new technologies coming online that can also
help provide reliability attributes. The deployment of many of these
technologies has been accelerating due to the incentives in the IRA.
The rapid increase in energy storage deployment across the nation is an
important part of future grid reliability, particularly as the duration
of storage assets expands. Examples of existing and emerging storage
resources include various types of fuel cells, batteries, pumped hydro-
electric reservoirs, and underground hydrogen caverns. Energy storage
can help buttress reliability by storing renewable energy for dispatch
when demand is high. Improved management of demand response assets,
better designed electricity tariff structures, aggregation of
distributed resources like roof-top solar panels, and integration of
behind-the-meter battery storage can further support balancing peak
demand on power grids. For example, programs to manage demand, which
have shown value well before the recent energy transition, incentivize
customers to shift their demand during periods when there is ample
supply, which can help reduce instances when supply is tight.
Despite these concerns, there are also existing procedures in place
to ensure electricity system reliability and resource adequacy over
both the short and long-term. For example, regional planning
organizations typically have incentive or planning procedures to ensure
that there is sufficient capacity to meet future demand such as day-
ahead reserve and capacity markets and seasonal reserve margins.
Furthermore, the EPA understands that before a unit implements a
retirement decision, the unit's owner will follow the processes put in
place by the relevant RTO, balancing authority, or state regulator to
protect electric system reliability. These processes typically include
analysis of the potential impacts of the proposed EGU retirement on
electrical system reliability, identification of options for mitigating
any identified adverse impacts, and, in some cases, temporary provision
of additional revenues to support the EGU's continued operation until
longer-term mitigation measures can be put in place.
C. Control and Treatment Technologies
In general, control and treatment technologies for some
wastestreams have continued to advance since the 2015 and 2020 rules.
Often, these advancements provide plants with additional approaches for
complying with any effluent limitations. In some cases, these
advancements have also decreased the associated costs of compliance.
For this rule, the EPA incorporated updated information and evaluated
several technologies available to control and treat FGD wastewater, BA
transport water, CRL, and legacy wastewater generated by the steam
electric power generating industry. See section VIII of this preamble
for details on updated cost information.
1. FGD Wastewater
FGD scrubber systems are used to remove sulfur dioxide from flue
gas so it is not emitted into the air. Dry FGD systems use water in
their operation but generally do not discharge wastewater because it
evaporates during operation. Wet FGD systems do produce a wastewater
stream.
Steam electric power plants discharging FGD wastewater currently
employ a variety of wastewater treatment technologies and operating/
management practices to reduce the pollutants associated with FGD
wastewater discharges. The EPA identified the following types of
treatment and handling practices for FGD wastewater:
<bullet> Chemical precipitation. Chemicals are added as part of the
treatment system to help remove suspended solids and dissolved solids,
particularly metals. The precipitated solids are then removed from the
solution by coagulation/flocculation followed by clarification and/or
filtration. The 2015 and 2020 rules focused on a specific design that
employs hydroxide precipitation, sulfide precipitation (organosulfide),
and iron coprecipitation to remove suspended solids and convert soluble
metal ions to insoluble metal hydroxides or sulfides. Chemical
precipitation was part of the BAT technology basis for the effluent
limitations in the 2015 and 2020 rules.
<bullet> High-hydraulic-residence-time biological reduction (HRTR).
The EPA
[[Page 40209]]
identified three types of biological treatment systems used to treat
FGD wastewater: anoxic/anaerobic fixed-film bioreactors (which target
removals of nitrogen compounds and selenium), anoxic/anaerobic
suspended growth systems (which target removals of selenium and other
metals), and aerobic/anaerobic sequencing batch reactors (which target
removals of organics and nutrients). An anoxic/anaerobic fixed-film
bioreactor designed to remove selenium and nitrogen compounds using
high hydraulic residence times of approximately 10 to 16 hours was part
of the BAT technology basis for the effluent limitations in the 2015
rule.
<bullet> Low-hydraulic-residence-time biological reduction (LRTR).
LRTR is a biological treatment system that targets removal of selenium
and nitrate/nitrite using fixed-film bioreactors in smaller, more
compact reaction vessels. This system differs from the HRTR biological
treatment system evaluated in the 2015 rule, in that the LRTR system is
designed to operate with a shorter residence time (approximately one to
four hours, compared to a residence time of 10 to 16 hours for HRTR)
while still achieving significant removal of selenium and nitrate/
nitrite. LRTR was part of the BAT technology basis for the effluent
limitations in the 2020 rule.
<bullet> Membrane filtration. A membrane filtration system (e.g.,
microfiltration, ultrafiltration, nanofiltration, forward osmosis,
electrodialysis reversal, or reverse osmosis (RO)) is designed
specifically for high-TDS and high-TSS wastestreams. These systems are
designed to minimize fouling and scaling associated with industrial
wastewater. These systems typically use pretreatment for potential
scaling agents (e.g., calcium, magnesium, sulfates) combined with one
or more type of membrane technology to remove a broad array of
particulate and dissolved pollutants from FGD wastewater. The membrane
filtration units may also employ advanced techniques, such as vibration
or creation of vortexes to mitigate fouling or scaling of the membrane
surfaces. Membrane filtration can achieve zero discharge by
recirculating permeate from an RO system back into plant operations.
<bullet> Spray evaporation. Spray evaporation technologies, which
include spray dry evaporators (SDEs) and other similar proprietary
variations, evaporate water by spraying fine misted wastewater into hot
gases. The hot gases allow the water to evaporate before contacting the
walls of an evaporation vessel, treating wastewater across a range of
water quality characteristics such as TDS, TSS, or scale forming
potential. Spray evaporation technologies use a less complex treatment
configuration than brine concentrator and crystallizer systems (see the
description of thermal evaporation systems) to evaporate water using a
heat source, such as a slipstream of hot flue gas or an external
natural gas burner. Spray evaporation technologies can be used in
combination with other volume reduction technologies, such as
membranes, to maximize the efficiency of each process. Concentrate from
an RO system can then be processed through the spray evaporation
technology to achieve zero discharge by recirculating permeate from the
RO system back into plant operations.
<bullet> Thermal evaporation. Thermal evaporation systems use a
falling-film evaporator (or brine concentrator), following a softening
pretreatment step, to produce a concentrated wastewater stream and a
distillate stream to reduce wastewater volume by 80 to 90 percent and
reduce the discharge of pollutants. The concentrated wastewater is
usually further processed in a crystallizer that produces a solid
residue for landfill disposal and additional distillate that can be
reused within the plant or discharged. These systems are designed to
remove the broad spectrum of pollutants present in FGD wastewater to
very low effluent concentrations.
<bullet> Some plants operate their wet FGD systems using approaches
that eliminate the discharge of FGD wastewater. These plants use a
variety of operating and management practices to achieve this,
including the following:
--Complete recycle. The FGD wastestream is allowed to recirculate.
Particulates (e.g., precipitates and other solids) are removed and
landfilled. Water is supplemented when needed to replace water that
evaporated or was removed with landfilled solids. This process does not
produce a saleable product (e.g., wallboard grade gypsum) but it does
not need a wastewater purge stream to maintain low levels of chlorides.
--Evaporation impoundments. Some plants located in warm, dry climates
use surface impoundments as holding basins where the FGD wastewater is
retained until it evaporates. The evaporation rate from these
impoundments is greater than the flow rate of the FGD wastewater and
amount of precipitation entering the impoundments; therefore, there is
no discharge to surface water.\21\ These impoundments must be large
enough to accommodate extreme precipitation events to prevent
overtopping and runoff.
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\21\ Such impoundments must be lined based on the requirements
in the CCR rule. This lining would significantly reduce the
potential for a discharge through groundwater that would be the
functional equivalent of a direct discharge to a WOTUS.
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--FA conditioning. Many plants that operate dry FA handling systems use
the water from their FGD system in the FA handling system to suppress
dust or improve handling and/or compaction characteristics in an on-
site landfill.
--Combination of wet and dry FGD systems. The dry FGD process involves
atomizing and injecting wet lime slurry, which ranges from
approximately 18 to 25 percent solids, into a spray dryer. The water
contained in the slurry evaporates from the heat of the flue gas within
the system, leaving a dry residue that is removed from the flue gas
using a fabric filter (i.e., baghouse) or electrostatic precipitator.
--Underground injection. These systems dispose of wastes by injecting
them into a permitted underground injection well as an alternative to
discharging wastewater to surface waters.
The EPA also collected information on other FGD wastewater
treatment technologies, including direct contact thermal evaporators
and ion exchange. These treatment technologies have been evaluated, in
full- or pilot-scale, or are being developed to treat FGD wastewater.
More information on these technologies is available in section 4.1 of
the Supplemental TDD.
2. BA Transport Water
BA (bottom ash) consists of heavier ash particles that are not
entrained in the flue gas and fall to the bottom of the furnace. In
most furnaces, the hot BA is quenched in a water-filled hopper.\22\
Some plants use water to transport (sluice) the BA from the hopper to
an impoundment or dewatering bins. The water used to transport the BA
to the impoundment or dewatering bins is usually discharged to surface
water as overflow from the systems after the BA has settled to the
bottom. The industry also uses the following BA handling systems that
generate BA transport water:
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\22\ Consistent with the 2015 and 2020 rule, EGU slag is
considered BA.
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<bullet> Remote mechanical drag system (MDS). These systems
transport BA to a remote MDS using the same processes as wet-sluicing
systems. A drag chain conveyor pulls the BA out of the water bath on an
incline to dewater the BA. The system can be operated either as a
[[Page 40210]]
closed-loop system (part of the technology basis for the 2015 rule) or
a high-recycle-rate system (technology basis for the 2020 rule).\23\
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\23\ In some cases, additional treatment may be necessary to
maintain a closed-loop system. This additional treatment could
include polymer addition to enhance removal of suspended solids or
membrane filtration of a slipstream to remove dissolved solids.
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<bullet> Mobile MDS. This technology is a smaller, mobile version
of a remote MDS with an additional clarification system. It is not
intended to be a permanent installation, which allows facilities to
reduce capital costs. Once in place, the system works like a remote
MDS--the incoming water is clarified and primary separation occurs. The
clarified water is taken from the mechanical drag system to a mobile
clarifier and polished to a level suitable for recirculation. The
mobile clarifier thickens the collected solids, which are then sent
back to the mechanical drag system portion and mixed with coarse BA.
This mixture is sent up an incline, dewatered, and disposed of.
<bullet> Dense slurry system. These systems use a dry vacuum or
pressure system to convey the BA to a silo (as described below for the
``dry vacuum or pressure system''), but instead of using trucks to
transport the BA to a landfill, the plant mixes the BA with a lower
percentage of water compared to a wet-sluicing system and pumps the
mixture to the landfill.
As part of the 2020 rule and this rule, the EPA identified the
following BA handling systems that do not, by definition or practice,
generate BA transport water.
<bullet> MDS. These systems are located directly underneath the
EGU. The BA is collected in a water quench bath. A drag chain conveyor
pulls the BA out of the water bath along an incline to dewater the BA.
<bullet> Dry mechanical conveyor. These systems are located
directly underneath the EGU. The system uses ambient air to cool the BA
in the boiler and then transports the ash out from under the EGU using
a conveyor. There is no water used in this process.
<bullet> Dry vacuum or pressure system. These systems transport BA
from the EGU to a dry hopper without using any water. Air is percolated
through the ash to cool it and combust unburned carbon. Cooled ash then
drops to a crusher and is conveyed via vacuum or pressure to an
intermediate storage destination.
<bullet> Vibratory belt system. These systems deposit BA on a
vibratory conveyor trough, where the ash is air-cooled and ultimately
moved through the conveyor deck to an intermediate storage destination
without using any water.
<bullet> Submerged grind conveyor. These systems are located
directly underneath the EGU and are designed to reuse slag tanks, ash
gates, clinker grinders, and transfer enclosures from the existing wet
sluicing systems. The system collects BA from the discharge of each
clinker grinder. A series of submerged drag chain conveyors transport
and dewater the BA.
More information on these technologies is available in section 4.2
of the Supplemental TDD.
3. CRL
In promulgating the 2015 rule, the EPA determined that CRL from
landfills and impoundments includes similar types of constituents as
FGD wastewater, albeit at potentially lower concentrations and smaller
volumes. Based on this characterization of the wastewater and knowledge
of treatment technologies, the EPA determined that certain treatment
technologies identified for FGD wastewater could also be used to treat
CRL. These technologies, described in section V.C.1 of this preamble,
include chemical precipitation, biological treatment (including LRTR),
membrane filtration, spray evaporation, or other thermal treatment
options. The EPA also identified other management and reuse strategies
from responses to the 2010 Questionnaire for the Steam Electric Power
Generating Effluent Guidelines, or steam electric survey, which
included using CRL from either an impoundment or landfill for moisture
conditioning FA, dust control, or truck wash. The EPA also identified
plants that collect CRL from impoundments and recycle it directly back
to the impoundment.
4. Legacy Wastewater
Legacy wastewater can be composed of FGD wastewater, BA transport
water, FA transport water, CRL, gasification wastewater and/or FGMC
wastewater generated before the ``as soon as possible'' date that more
stringent effluent limitations from the 2015 or 2020 rules would apply.
Discharges of legacy wastewater may occur through an intermediary
source (e.g., a tank or surface impoundment) or directly into a surface
waterbody, with the vast majority of legacy wastewater currently
contained in surface impoundments resulting from treating the
wastestreams listed above to the previously established BPT
limitations. The record indicates that the following technologies can
be applied to treat this type of legacy wastewater: chemical
precipitation, biological treatment (including LRTR), membrane
filtration, spray evaporation, and other thermal treatment options.
These technologies are described in section V.C.1 of this preamble.
Another option, which may be used in combination with other systems
such as chemical and physical treatment, is zero valent iron (ZVI).
<bullet> ZVI. This technology can be used to target specific
inorganics, including selenium, arsenic, nitrate, and mercury in this
type of legacy wastewater. The technology entails mixing influent
wastewater with ZVI (iron in its elemental form), which reacts with
oxyanions, metal cations, and some organic molecules in wastewater. ZVI
causes a reduction reaction in these pollutants, after which the
pollutants are immobilized through surface adsorption onto iron oxide
coated on the ZVI or generated from oxidation of elemental iron. The
coated, or spent, ZVI is separated from the wastewater with a
clarifier. The quantity of ZVI required and number of reaction vessels
can vary based on the composition and amount of wastewater being
treated.
The EPA recognizes that the characterization of legacy wastewater
differs within the layers of a CCR impoundment as it is dewatered and
prepared for closure. Therefore, treatment requirements may change as
closure continues. Wastewater characteristics may also differ across
CCR impoundments due to the different types of fuels burned at the
plant, duration of pond operation, and ash type. Each of the treatment
technologies identified for legacy wastewater above is applicable to
all legacy wastewaters; treatment may require a combination of those
technologies (e.g., chemical precipitation and membrane filtration).
In addition, solids dewatering is necessary to dredge CCR materials
from the impoundment. Mobile dewatering systems are typically self-
contained units on a trailer, allowing for the entire system to be
easily moved on-site and off-site. Legacy wastewater from a holding
area (e.g., pit, pond, collection tank) is pumped through a filter
press to generate a filter cake and water stream. A shaker screen can
be added to the treatment train to remove larger particles prior to the
filter press. Furthermore, the filter press can be equipped with
automated plate shifters to allow solids to drop from the end of the
trailer directly into a loader or truck. The resulting wastestream may
be further treated to meet any discharge requirements.
[[Page 40211]]
VI. Data Collection Since the 2020 Rule
A. Information from the Electric Utility Industry
1. Data Requests and Responses
In January 2022, the EPA requested the following pollution
treatment system performance and cost information for coal-fired power
plants from three steam electric power companies:
<bullet> FGD wastewater installations of the following
technologies: thermal technology; membrane filtration technology;
paste, solidification, or encapsulation of FGD wastewater brine;
electrodialysis; and electrocoagulation.
<bullet> Overflow from an MDS, a compact submerged conveyor, or
remote MDS installations, including purge rate and management from
remote MDS systems, as well as any pollutant concentration data to
characterize the overflow or purge.
<bullet> CRL treatment from on-site or off-site testing (full-,
pilot-, or laboratory-scale).
<bullet> On-site or off-site testing (full-, pilot-, or laboratory-
scale) and/or implementation of treatment technologies associated with
surface impoundment dewatering treatment.
<bullet> Costs associated with these technologies.
In addition, after meeting with four additional power companies,
the EPA sent each company a voluntary request inviting them to provide
the same data described above.
In July 2023, the EPA requested any full-, pilot-, or laboratory-
scale data associated with on-site or off-site testing or
implementation of a recently commissioned spray dryer evaporator for
FGD wastewater and legacy wastewater at a coal-fired power plant from
Minnesota Power. The EPA also requested information on pretreatment or
disposal systems necessary for continued spray dryer evaporator
operations and any corresponding documentation (e.g., wastestreams
generated, process flow diagram).
2. Meetings With Individual Utilities
To gather information to support this supplemental rule, the EPA
met with representatives from four utilities. Two of these utilities
reached out to the EPA after the announcement of the supplemental
rulemaking. The EPA contacted the remaining utilities due to their
known or potential consideration of membrane filtration. At these
meetings, the EPA discussed the operation of the utility's coal-fired
EGUs and the treatment and management of BA transport water, FGD
wastewater, legacy wastewater, and CRL since the 2020 rule. The EPA
learned about updates associated with plant operations and studies at
these plants, which were originally discussed during the 2015 and 2020
rules.
The objectives of these meetings were to gather general information
about coal-fired power plant operations; pollution prevention and
wastewater treatment system operations; ongoing pilot or laboratory
scale study information for FGD wastewater treatment; BA system
performance, characterization, and quantification of the overflow and
purge from remote MDS installations; and treatment technologies and
pilot testing associated with CRL and legacy wastewater. The EPA used
this information to supplement the data collected in support of the
2015 and 2020 rules.
3. Voluntary CRL Sampling
In December 2021, the EPA invited eight steam electric power
companies to participate in a voluntary program designed to obtain data
to supplement the wastewater characterization data set for CRL. The EPA
requested these data from facilities believed to have constructed new
landfills pursuant to the 2015 CCR rule. Six power companies chose to
participate in this program. The EPA incorporated these data into the
CRL analytical dataset used to estimate pollutant loadings. More
information on estimated CRL pollutant loadings is available in section
6 of the Supplemental TDD.
4. Electric Power Research Institute Voluntary Submission
The Electric Power Research Institute (EPRI) conducts industry-
funded studies to evaluate and demonstrate technologies that can
potentially remove pollutants from wastestreams or eliminate
wastestreams using zero-discharge technologies. Following the 2015
rule, the EPA reviewed 35 EPRI reports published between 2011 and 2018
that were voluntarily provided regarding characteristics of FGD
wastewater, FGD wastewater treatment pilot studies, BA transport water
characterization, BA handling practices, halogen addition rates, and
the effect of halogen additives on FGD wastewater. For this
supplemental rule, EPRI provided an additional 25 reports generated
since 2018. The EPA used the information in these reports to inform
treatment technology performance and to update methodologies for
estimating costs and pollutant removals associated with candidate
treatment technologies.
5. Meetings With Trade Associations
In 2021 and 2022, the EPA met with the Edison Electric Institute
and the American Public Power Association. These trade associations
represent investor-owned utilities and community-owned utilities,
respectively. They provided information and perspectives on the status
of many utilities transitioning away from coal. The EPA also
participated in meetings with one trade association following the 2023
proposed rule. This association requested meetings with the EPA to
discuss the association's public comments.
B. Notices of Planned Participation
The 2020 rule required facilities to file a Notice of Planned
Participation (NOPP) with their permitting authority no later than
October 13, 2021, if the facility wished to participate in the LUEGU
subcategory, the permanent cessation of coal combustion by 2028
subcategory, or in the VIP. For the permanent cessation of coal
combustion by 2028 subcategory, this filing date was extended by a 2023
direct final rule to June 27, 2023. 88 FR 18440. While the facilities
were not required to provide copies of the NOPPs to the Agency, the EPA
nevertheless obtained a number of these filings. Some facilities
provided the EPA a courtesy copy when filing with the relevant
permitting authority. The Agency received notice of other filings when
a state permitting authority sent new draft permits or modifications to
the EPA for review. The EPA also asked some states for NOPPs after
those states asked the EPA questions about the process or initiated
discussions about specific plants. Environmental groups that collected
some additional information about NOPPs also shared the information
with EPA prior to the publication of the proposed rule.
The EPA is currently aware of NOPPs covering 94 EGUs at 38 plants.
At the time of the proposed rule, four EGUs (at two plants) requested
participation in the LUEGU subcategory, an additional 12 EGUs (at four
plants) requested participation in the 2020 rule VIP, and the remaining
74 EGUs (at 33 plants) requested participation in the permanent
cessation of coal combustion by 2028 subcategory.\24\ Following the
2023 direct final rule, the EPA obtained one additional NOPP stating
that two EGUs (at one plant) requested participation in the permanent
cessation
[[Page 40212]]
of coal combustion subcategory by 2028 instead of the 2020 rule VIP.
The EPA notes that these counts are not a comprehensive picture of
facilities' plans for two reasons. First, the EPA was unable to obtain
information for all plants and states. Second, even where a facility
has filed a NOPP, under the transfer provisions of 40 CFR
423.13(o)(1)(ii), it still retains flexibility to transfer between
subcategories, or between a subcategory and the 2020 VIP provisions,
until December 31, 2025.\25\ For example, the EPA made industry profile
updates to some of the 90 EGUs with corresponding NOPPs based on public
comments and other power company data (e.g., integrated resource
planning reports). For further detail, the NOPPs the EPA is aware of
have been placed in the docket along with a memorandum summarizing the
information and providing record index numbers for locating each
facility, entitled Changes to Industry Profile for Coal-Fired
Generating Units for the Steam Electric Effluent Guidelines Final Rule
(DCN SE11618).
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\24\ Plant Scherer filed a permanent cessation of coal
combustion by 2028 NOPP for two EGUs and a 2020 rule VIP NOPP for
the remaining two EGUs; thus, the plant count for the three
groupings does not equal 38.
\25\ The ability to transfer into the LUEGU subcategory ended on
December 31, 2023.
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C. Information from Technology Vendors and Engineering, Procurement,
and Construction Firms
The EPA gathered data on the availability and effectiveness of FGD
wastewater, BA handling, CRL, and surface impoundment dewatering
operations and wastewater treatment technologies from technology
vendors and engineering, procurement, and construction firms through
presentations, conferences, meetings, and email and phone contacts.
These collected data informed the development of the technology costs
and pollutant removal estimates for FGD wastewater, BA transport water,
CRL, and legacy wastewater.
D. Other Data Sources
The EPA gathered information on steam electric generating
facilities from the DOE's Energy Information Administration (EIA) Forms
EIA-860 (Annual Electric Generator Report) and EIA-923 (Power Plant
Operations Report). The EPA used the 2019, 2020, and 2021 data to
update the industry profile, including commissioning dates, energy
sources, capacity, net generation, operating statuses, planned
retirement dates, ownership, and pollution controls at the EGUs. The
EPA also referenced 2022 EIA data to support the analysis of FGD
halogen (bromide and iodine) loads. Finally, the EPA used a 2024 EIA
study as the basis for estimating the costs of a new coal-fired steam
power plant.\26\
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\26\ U.S. Energy Information Administration (2024). Capital Cost
and Performance Characteristics for Utility-Scale Electric Power
Generating Technologies, available at: <a href="https://www.eia.gov/analysis/studies/powerplants/capitalcost/pdf/capital_cost_AEO2025.pdf">https://www.eia.gov/analysis/studies/powerplants/capitalcost/pdf/capital_cost_AEO2025.pdf</a>.
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The EPA conducted literature and internet searches to gather
information on FGD wastewater treatment technologies, including
information on pilot studies, applications in the steam electric power
generating industry, and implementation costs and timelines. The EPA
also used internet searches to identify or confirm reports of planned
facility plant and EGU retirements and reports of planned unit
conversions to dry or closed-loop recycle ash handling systems. The EPA
used this information to inform the industry profile and identify
process modifications occurring in the industry.
VII. Final Regulation
A. Description of the Options
The EPA analyzed four main regulatory options at proposal, the
details of which were discussed in the proposed rule. See 88 FR 18824,
18837-18838 (Mar. 29, 2023). For the final rule, the EPA evaluated
three main regulatory options, as shown in table VII-1 of this
preamble. Option A corresponds to the proposed regulation with
modifications, while Options B and C would require controls that would
achieve greater pollutant reductions. All three options include the
same technology basis for FGD wastewater (zero-discharge systems) and
BA transport water (dry-handling or closed-loop systems), while
incrementally increasing controls on CRL and legacy wastewater and
removing certain subcategories as one moves from Option A to Option C.
Each successive option from Option A to Option C would achieve a
greater reduction in wastewater pollutant discharges. Each
subcategorization is described further in section VII.C of this
preamble.
1. FGD Wastewater
Under all three main options, the EPA would require zero discharge
of FGD wastewater based on zero-discharge technologies and retain the
2020 FGD wastewater limitations and standards as an interim step toward
achievement of zero-discharge requirements. Under all three options,
the EPA would also eliminate the BAT and PSES subcategorizations for
high-FGD-flow facilities and LUEGUs. Options A and B would also create
a subcategory for EGUs that will permanently cease coal combustion no
later than December 31, 2034, and instead of zero discharge would
require discharges from these facilities to meet the 2020 rule
limitations as included in their CWA permit. This subcategory modifies
the proposed early adopters subcategory and is described further in
section VII.C of this preamble. Under Option C, the EPA would not
finalize a subcategory for those EGUs planning to cease coal combustion
by December 31, 2034. Note that, for all three options, the EPA would
retain the 2020 subcategory for EGUs permanently ceasing coal
combustion by 2028.
2. BA Transport Water
Under all three main options, the EPA would require zero discharge
of BA transport water based on dry-handling or closed-loop systems and
retain the 2020 BA transport water limitations and standards as an
interim step toward achievement of zero-discharge requirements. For all
three options, the EPA would also eliminate the BAT and PSES
subcategorizations for LUEGUs. Options A and B would also create a
subcategory for EGUs that will permanently cease coal combustion no
later than December 31, 2034, and instead would require discharges from
these facilities to meet the 2020 rule limitations as permitted. Under
Option C, the EPA would not finalize this subcategory. Note that, for
all three options, the EPA would retain the 2020 subcategory for EGUs
permanently ceasing coal combustion by 2028.
3. CRL
Under Option A, the EPA would establish BAT limitations and PSES
for mercury and arsenic based on chemical precipitation treatment.
Under Options B and C, BAT limitations and PSES would be zero discharge
and the EPA would establish BAT limitations for mercury and arsenic
based on chemical precipitation for discharges of unmanaged CRL.
Options A and B would also create a subcategory for EGUs that would
permanently cease coal combustion no later than December 31, 2034; CRL
discharges from EGUs in this subcategory would be subject to case-by-
case BPJ decision-making until permanent cessation of coal combustion,
after which they would be subject to mercury and arsenic limitations
based on chemical precipitation. Under Option C, the EPA would not
finalize this subcategory.
4. Legacy Wastewater
Under Option A, the EPA would not specify a nationwide technology
basis for BAT/PSES applicable to legacy
[[Page 40213]]
wastewater at this time and such limitations would be derived on a
site-specific basis by the permitting authorities, using their BPJ.
Under Options B and C, the EPA would establish a subcategory for
discharges of legacy wastewater discharged from surface impoundments
commencing closure after July 8, 2024. For such discharges, the EPA
would establish mercury and arsenic limitations based on chemical
precipitation.
[[Page 40214]]
[GRAPHIC] [TIFF OMITTED] TR09MY24.039
[[Page 40215]]
[GRAPHIC] [TIFF OMITTED] TR09MY24.040
B. Rationale for the Final Rule
After considering the technologies described in this preamble and
the TDD, as well as public comments, and in light of the factors
specified in CWA sections 301(b)(2)(A) and 304(b)(2)(B) (see section IV
of this preamble), the EPA is establishing BAT effluent limitations
based on the technologies described in Option B.\27\ While the EPA is
establishing new BAT effluent limitations for FGD wastewater and BA
transport water based on more stringent technologies than the 2020
rule, the EPA is retaining the 2020 rule BAT effluent limitations for
discharges before the applicability dates for new limitations on these
wastewaters.
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\27\ The EPA is including severability language in the final
rule that makes clear that if any provisions of the final rule are
reviewed and vacated by a court, it is the EPA's intent that as many
portions of the rule remain in effect as possible.
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1. FGD Wastewater
The EPA is identifying zero-discharge systems as the technology
basis for establishing BAT limitations to control pollutants discharged
in FGD wastewater.\28\ More specifically, the technology basis for BAT
is membrane filtration systems, SDEs, and thermal evaporation systems,
alone or in any combination, including any necessary pretreatment
(e.g., chemical precipitation) or post-treatment (e.g.,
crystallization).\29\ Furthermore, where a permeate or distillate is
generated from the final stage of treatment, the BAT technology basis
uses a process wherein this water would then be recycled back into the
plant as either FGD makeup water or EGU makeup water.\30\ After
considering the factors specified in CWA section 304(b)(2)(B), the
record shows that this suite of technologies is technologically
available, is economically achievable, and has acceptable non-water
quality environmental impacts. It is the EPA's intent that these three
technologies considered together constitute BAT for FGD wastewater, and
the EPA concludes that this BAT basis meets the requisite statutory
factors. The EPA also finds, however, that each of the individual
technologies within this suite supports a BAT determination on its own.
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\28\ As described in section VII.B.5 of this preamble, the EPA
is also finalizing a definitional change to certain wastewaters,
including FGD wastewater, that excludes discharges necessary as a
result of high intensity, infrequent storm events, as well as
wastewater removed from FGD wastewater treatment equipment within
the first 120 days of decommissioning the equipment.
\29\ While three main technologies are listed here and are used
to evaluate costs and non-water quality environmental impacts, the
list is not meant to exclude use of other known zero-discharge
treatment processes, including FA fixation, direct encapsulation, or
evaporation ponds.
\30\ The 2020 rule finalized a carve out from the definition of
FGD wastewater applicable to ``treated FGD wastewater permeate or
distillate used as boiler makeup water.''
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In the following subsections, the EPA discusses its rationale for
selecting three zero-discharge systems as BAT for the control of FGD
wastewater, as well as how each individual zero-discharge technology
supports the BAT technology basis on its own. The EPA also explains why
it is not selecting a less stringent technology as BAT. For further
discussion of the changes (now being finalized by the EPA) to the
definition of FGD wastewater related to infrequent storm events and
decommissioning wastewater, see section VII.B.5 of this preamble. For
further discussion of the EPA's retention of the 2020 rule limitations
as interim limitations, see section VII.C.7 of this preamble.
a. The EPA selects zero-discharge systems as BAT for FGD
wastewater.
Technological availability of zero-discharge systems. At proposal,
the EPA identified membrane filtration as a potential BAT on which to
base zero-discharge limitations for FGD wastewater, but also solicited
comment on several other zero-discharge technologies, such as thermal
evaporation systems and SDEs, that the EPA thought might serve alone or
in any combination as the BAT basis for a final rule.
The EPA received many comments that were specific to individual
zero-discharge technologies, including both comments supporting and
opposed to a finding of technological availability for these individual
technologies as part of the BAT basis. Comments supporting zero-
discharge limitations pointed to the large number of operating zero-
discharge plants and pilot studies as evidence that more than just the
best performing plant or pilot plants are using zero-discharge systems.
Comments opposing such a finding primarily focused on membrane
filtration, the EPA's proposed zero-discharge technology basis under
the preferred regulatory option. The two concerns raised most commonly
in opposition to the finding of membrane filtration availability were,
first, that the EPA did not collect sufficient additional information
to alter its findings in the 2020 rule regarding this technology's
availability and, second, that the pilot studies and foreign plants
cited by the EPA were conducted on small FGD wastewater flows that were
not representative of domestic industry operations. For both membrane
filtration systems and thermal evaporation systems, commenters who
opposed a finding of availability also questioned whether back-end
management options were available for the associated wastes from zero-
discharge systems. To the extent it received comments suggesting that
waste management alternatives are not available, the EPA has addressed
these comments in the subsection discussing non-water quality
environmental impacts, below.
After consideration of public comments and as further discussed
below, the EPA is basing its determination that zero-discharge systems
are available for control of pollutants found in FGD wastewater on the
numerous full-scale domestic and foreign installations of zero-
discharge systems to treat FGD wastewater, the large number of
successful domestic and international pilot tests of zero-discharge
systems on FGD wastewater, successful use of zero-discharge systems on
other steam electric wastestreams, and the use of zero-discharge
systems on wastestreams in many different industries besides the steam
electric power generating industry. Alternatively, the EPA is basing
its determination that each of the technologies that make up the suite
of zero-discharge systems forming the BAT basis, standing alone, is
available on the several full-scale domestic and/or
[[Page 40216]]
foreign installations of each of these technologies to treat FGD
wastewater and/or the successful domestic and international pilot tests
of each of these technologies on FGD wastewater. The availability of
each technology standing alone is also supported by the successful use
of each of these technologies on other steam electric wastestreams and/
or the use of each of these technologies on wastestreams in different
industries besides the steam electric power generating industry. The
weight of the evidence supports the Agency's conclusion that the suite
of zero-discharge systems (or each of the individual technologies
alone) are available in the industry to control FGD wastewater
discharges, notwithstanding certain uncertainties the EPA described in
the 2020 rule about one of the technologies that form the zero-
discharge BAT technology basis. Agencies have inherent authority to
reconsider past decisions and to revise, replace, or repeal a decision
to the extent permitted by law and supported by a reasoned explanation.
FCC v. Fox Television Stations, Inc., 556 U.S. 502, 515 (2009); Motor
Vehicle Mfrs. Ass'n v. State Farm Mutual Auto. Ins. Co., 463 U.S. 29,
42 (1983). A finding that zero-discharge systems are available, or that
each of the zero-discharge technologies forming the BAT basis is
available, is also consistent with the technology-forcing nature of BAT
as described in the legislative history and legal precedents discussing
this provision (see section IV.B.2 of this preamble).
Full-scale domestic zero-discharge systems. In the 2020 rule, the
EPA rejected membrane filtration as a standalone BAT technology basis
due in part to the lack of a single full-scale domestic installation,
which is still the case today. In that rule, however, the EPA did not
evaluate a technology basis that includes the three zero-discharge
technologies that form this final rule's BAT basis.
First, the EPA notes that 40 coal-fired power plants in the United
States currently (as of 2024) operate wet FGD systems and manage their
wastewater to achieve zero discharge.\31\ These plants achieve zero
discharge using evaporation ponds, recycling of FGD wastewater, ash
fixation, thermal evaporation systems (e.g., falling film evaporators),
or SDEs. About 19 additional plants operated zero-discharge systems for
FGD wastewater since 2009 but have since retired or converted fuels
such that the FGD wastewater generation, and associated zero-discharge
operations, have ceased. In total, more domestic facilities operate, or
have operated, zero-discharge systems than the biological treatment
systems used as the 2015 and 2020 rule bases.\32\ Not only are there
more of these systems, but the systems for which the EPA has
information have achieved continuous, long-term zero discharge.
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\31\ One of these 40 plants, which was already achieving zero
discharge of its FGD wastewater, is now installing SDE. See <a href="https://www.woodplc.com/insights/articles/engineering-solutions-for-wastewater-treatment">https://www.woodplc.com/insights/articles/engineering-solutions-for-wastewater-treatment</a> (DCN SE10284).
\32\ The EPA accounted for four plants operating biological
treatment systems in the 2015 rule analyses (DCN SE05832) and nine
plants in the 2020 rule analyses (DCN SE08629).
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With respect specifically to the BAT basis identified in this final
rule, the EPA finds that there are four U.S. coal-fired power plants
currently operating full-scale thermal and three U.S. coal-fired power
plants currently operating full-scale SDE systems.\33\ The full-scale
domestic application of the technologies identified in the BAT basis
for this final rule support the EPA's finding that the BAT technology
basis is available, as that term is used in the CWA. It also supports a
finding that thermal evaporation systems are technologically available
on their own and that SDEs are technologically available on their own.
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\33\ In the 2020 rule and 2023 proposal, the EPA has continually
deferred to one company's representations that, contrary to
representations from the technology vendor, its membrane filtration
system is a long-term pilot system rather than a full-scale
installation. This is a distinction without a difference, as the EPA
can rely on both full-scale installations and pilot plants in
establishing BAT limitations. Therefore, the EPA addresses this
system in the section on pilot systems below (even though it could
arguably be used to treat the facility's entire wastestream in the
future).
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Full-scale, foreign zero-discharge systems and zero-discharge pilot
plants. While the full-scale, domestic operation of zero-discharge
systems is sufficient to determine availability of the BAT technology
basis, the EPA has also identified a number of full-scale, foreign
zero-discharge systems, as well as domestic and international pilot
systems; these could additionally or separately support the EPA's
conclusion that the BAT basis identified in this final rule is
available.
In 2020, the EPA declined to find that full-scale, foreign
installations of membrane filtration demonstrated the availability of
that technology, in large part because the EPA had not visited these
systems or obtained long-term performance data on them, and thus stated
there were uncertainties around these applications that prevented a
finding of availability. At the time of the 2020 rule, the Agency cited
12 foreign installations of membrane filtration systems on FGD
wastewater.\34\ These systems began operating as early as 2015, and all
of them were designed to operate as zero-discharge systems.\35\
Importantly, however, the EPA did not dispute the availability of
thermal evaporation systems in the 2020 rule. This is consistent with
the record, as even at the time of the 2015 rule, the EPA visited three
thermal evaporation systems operating in Italy, obtaining relevant
performance data on these systems, which it then used to establish BAT
limitations for a voluntary incentive program based on such technology,
as well as NSPS for FGD wastewater.\36\
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\34\ ERG. 2020. Technologies for the Treatment of Flue Gas
Desulfurization Wastewater (DCN SE09218); ERG. 2020. Notes from Call
with DuPont (DCN SE08618); Beijing Jingneng Power. 2017. Beijing
Jingneng Power Company, Ltd. Announcement on Unit No. 1 of the Hbei
Shuoshou Jingyuan Thermal Power Co., Ltd. Passing Through the 168-
hours Trial Operation. November 13 (DCN SE08624); Broglio, R. 2019.
Vendor FGD Wastewater Treatment Details--Doosan. July 15 (DCN
SE07107); Lenntech. 2020. Lenntech Water Treatment Solutions. Flue
Gas Desulfurization Treatment (DCN SE08622); Nanostone. 2019. China
Huadian Jiangsu Power Jurong Power Plant FGD Wastewater Zero Liquid
Discharge Project was Awarded the Engineering Star Award. June 27
(DCN SE08623).
\35\ Technologies for the Treatment of Flue Gas Desulfurization
Wastewater, Coal Combustion Residual Leachate, and Pond Dewatering
(DCN SE11695).
\36\ This information was also used as the basis for the 2015
rule NSPS for FGD wastewater.
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Some commenters on the 2023 proposal reiterated the EPA's 2020 rule
findings and argued that EPA has not collected sufficient new
information on foreign installations of membrane filtration to reverse
its 2020 findings. EPA first notes that, for this final rule, it has
modified its BAT basis from proposal to consist of three zero-discharge
systems (each of which was described in the proposal). Since the 2015
rule, EPA has collected information not just about membrane filtration
systems abroad, but also about an additional four thermal evaporation
systems and six SDE systems operating on FGD wastewater outside the
United States.\37\ The EPA finds that, when combined with the site
visits and performance data EPA obtained on the three Italian thermal
evaporation systems as part of the 2015 rulemaking, the current record
is more than sufficient to determine, based on full-scale, foreign
installations, that the suite of systems forming the BAT basis in this
rule is available as that term is used in the CWA.
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\37\ Technologies for the Treatment of Flue Gas Desulfurization
Wastewater, Coal Combustion Residual Leachate, and Pond Dewatering
(DCN SE11695).
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[[Page 40217]]
Furthermore, even looking at membrane filtration itself, as the EPA
noted in the 2023 proposal, the foreign membrane filtration systems
discussed in the 2020 rule have continued to successfully treat FGD
wastewater and achieve zero discharge since 2020. Despite commenters
arguing that this additional information is not important because it
does not change the overall number of plants known to operate the
technology or the number of influent and effluent concentration data
points collected from these plants, the EPA finds that continued
operations constitute significant new information. This is because the
longer each zero-discharge system operates, the less probability that
some yet unknown operational difficulty will appear and the more
certainty the EPA has that the technology is capable of achieving long-
term zero-discharge treatment of this wastewater. Thus, foreign
installations of the suite of technologies forming the BAT basis
support the EPA's conclusion that the BAT basis is available as that
term is used in the CWA. At the same time, use of thermal evaporation
systems abroad supports a finding that thermal evaporation systems are
technologically available on their own, use of SDEs abroad supports a
finding that SDEs are technologically available on their own, and use
of membrane filtration systems abroad support a finding that membrane
filtration is technologically available on its own.
With respect to pilot studies, the 2020 rule found that pilot
projects on membrane filtration did not provide sufficient long-term
concentration data on which to base a finding of availability or
calculate limitations.\38\ Commenters on the 2023 proposal reiterated
the EPA's 2020 rule findings and suggested that the EPA had not
supplemented the record with enough pilot studies to reach a new
conclusion on availability. The EPA disagrees. The Agency first notes
that the BAT technology basis in this final rule has been updated to
consist of three zero-discharge systems. When the 13 thermal pilot
projects and one SDE pilot project on FGD wastewater in the record are
combined with the 30 membrane filtration pilots on FGD wastewater
discussed in the proposed rule (including eight pilot studies conducted
since the 2020 rule), the EPA has significant evidence of the ability
of this suite of systems to handle a variety of operating
conditions.\39\ These domestic and foreign pilots have demonstrated
success removing pollutants from FGD wastewater under a number of
pretreatment settings, whether performed without chemical precipitation
pretreatment, with chemical precipitation pretreatment, or following
biological treatment.\40\ Furthermore, while some systems will not
generate a clean permeate or distillate that needs to be handled, those
that do will recycle this clean water source back into the plant to
meet the final zero-discharge limitations. Thus, long-term pollutant
removal information is no longer as relevant as it was in 2020 because
the EPA is not calculating nonzero limitations in this final rule.
While this discussion of pilot projects is used to support the
availability of the BAT technology basis comprised of multiple
technologies, the large number of successful pilot projects of membrane
filtration and thermal evaporation systems also supports the EPA's
finding that these individual technologies are available on their own.
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\38\ The EPA nevertheless established limitations based on
membrane filtration technology in the 2020 VIP.
\39\ One of the systems is a long-term pilot project at one
facility, which is a commercial-scale system that may have
sufficient capacity to treat the full FGD wastestream moving
forward. Nevertheless, because the company is still making changes
to the operation of the plant's FGD system, has also pilot tested a
biological treatment system, and has continued to leave the
possibility of biological treatment for compliance open, the EPA
defers to the company's characterization of this system as a pilot,
rather than a domestic, full-scale installation.
\40\ In one case, a utility conducted a successful membrane
pilot even when there were significant failures in the performance
of upstream pretreatment systems leading to excessive TSS
passthrough to the membrane system.
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In comments, one recurring criticism of the 2023 proposal was that
conclusions about membrane filtration system availability should not be
drawn from foreign installations and pilot plants due to their small
FGD wastewater flow rates. While the EPA acknowledges that foreign
installations and pilot plants may have had smaller FGD wastewater flow
rates than some of the plants the Agency expects would use this
technology to meet the final limitations in this rule, this does not
weigh against the EPA considering them as evidence of the technology's
availability because the record shows that membrane filtration systems
can be readily modified to handle different flow rates. This same
comment was raised as far back as the 2015 rule with respect to thermal
evaporation systems. At that time, the EPA responded to comments on the
scalability of zero-discharge thermal evaporation systems:
Additionally, even if the flow rates were smaller, the fact that
the technology can treat the FGD wastewater demonstrates that the
system is available, and the size of the system does not matter
because the system design can be scaled and designed to accommodate
different flow rates.\41\
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\41\ U.S. EPA (Environmental Protection Agency). 2015. Effluent
Limitations Guidelines and Standards for the Steam Electric Power
Generating Point Source Category: EPA's Response to Public Comments.
Part 6 of 10. Page 6-40.
The EPA has not received information since 2015 that suggests that
technologies are no longer scalable to higher flows. With respect to
membrane filtration scalability, in particular, the most common system
design for operating membrane filtration technologies is to place
modules of these systems in parallel and simply add more and more
stacks to treat higher and higher flows. Therefore, the EPA concludes
that use of zero-discharge systems in smaller flow rate pilots and
full-scale foreign facilities supports the finding that the BAT
technology basis is available; these uses also support the EPA's
finding that each of the individual technologies forming the BAT
technology basis are available on their own.\42\
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\42\ It is also possible that some plants may choose to treat
only a slipstream of FGD wastewater with a similarly small flow rate
to keep the system closed loop.
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Application to other wastestreams. While the record above is
sufficient to determine that the BAT basis of several zero-discharge
systems is available, use of the BAT basis on other wastewaters also
supports the EPA's finding regarding its availability. In the 2020
rule, the EPA declined to find that membrane filtration treatment of
non-FGD wastewaters was sufficient to support a finding of
availability. In that rule, EPA's conclusions were based on the ways in
which each non-FGD wastewater appeared different from FGD wastewater.
The EPA first notes that the BAT basis includes three zero-discharge
systems, not just membrane filtration. When considering the success
with which this suite of zero-discharge systems has operated on non-FGD
wastewater that has similar characteristics to FGD wastewater, the EPA
views application of these systems to such non-FGD wastewater as
supporting EPA's conclusion that the suite of zero-discharge
technologies identified as BAT in this rule is in fact available.
Examining all three zero-discharge systems that constitute the
basis for BAT, these systems are used in full-scale applications to
other wastestreams in the steam electric power sector and other
industrial sectors. The domestic steam electric power sector applies
[[Page 40218]]
membrane filtration and thermal evaporation systems to EGU makeup
water,\43\ cooling tower blowdown,\44\ and ash transport water.\45\
Other industrial sectors with full-scale applications of membrane
filtration, thermal evaporation, and SDE systems include the
textiles,\46\ chemical manufacturing,\47\ mining,\48\ agriculture, \49\
oil and gas extraction,\50\ food and beverage,\51\ landfills,\52\ and
automotive industries.\53\
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\43\ EPRI (Electric Power Research Institute). 2015. State of
Knowledge: Power Plant Wastewater Treatment--Membrane Technologies.
August. 3002002143.
\44\ See, e.g., Drake, M., Wise, S., Charan, N., Venkatadri, R.
2012. ZLD Treatment of Cooling Tower Blowdown with Membranes.
WaterWorld. December 1. Available online at: <a href="https://www.watertechonline.com/process-water/article/16211541/zld-treatment-of-cooling-tower-blowdown-with-membranes">https://www.watertechonline.com/process-water/article/16211541/zld-treatment-of-cooling-tower-blowdown-with-membranes</a> (DCN SE09089);
ERG. 2019. Final Notes from Meeting with New Logic Research. July
22. (DCN SE07231) ERG. 2019. Final Aquatech Meeting Notes. July 26
(DCN SE07389).
\45\ See, e.g., <a href="https://www.ge.com/in/sites/www.ge.com.in/files/GE_solves_ash%20pond_capacity_issue.pdf">https://www.ge.com/in/sites/www.ge.com.in/files/GE_solves_ash%20pond_capacity_issue.pdf</a> (DCN SE09090).
\46\ ERG. 2020. Final Notes from Call with DuPont (DCN SE08618).
\47\ ERG. 2020. Final Notes from Call with DuPont (DCN SE08618);
U.S. EPA (Environmental Protection Agency). 2022. Notes from Vendor
Call with Vacom on October 27, 2021. November 14 (DCN SE10367).
\48\ ERG. 2019. Final Notes from Meeting with Pall Water. March
5. EPA-HQ-OW-2009-0819-7613; Wolkersdorfer, C., et al. 2015.
Intelligent mine water treatment--recent international developments.
July 21 (DCN SE08581); U.S. EPA (Environmental Protection Agency).
2014. Office of Superfund and Remediation and Technology Innovation.
Reference Guide to Treatment Technologies for Mining-Influenced
Water. EPA 542-R-14-001. March (DCN SE08582); ERG. 2019. Final
Aquatech Meeting Notes. July 26 (DCN SE07389); U.S. EPA
(Environmental Protection Agency). 2022. Notes from Vendor Call with
Vacom on October 27, 2021. November 14. (DCN SE10367).
\49\ U.S. EPA (Environmental Protection Agency). 2022. Notes
from Meeting with BKT--April 9, 2021 (DCN SE10253).
\50\ ERG. 2018. Final Oasys Meeting Notes. February 16 (DCN
SE06915); ERG. 2019. Final Aquatech Meeting Notes. July 26 (DCN
SE07389); ERG. 2019. Final Veolia Meeting Notes. August 30 (DCN
SE07818); U.S. EPA (Environmental Protection Agency). 2022. Notes
from Vendor Call with Purestream on October 26, 2021. November 14
(DCN SE10366); U.S. EPA (Environmental Protection Agency). 2022.
Notes from Vendor Call with Vacom on October 27, 2021. November 14
(DCN SE10367).
\51\ U.S. EPA (Environmental Protection Agency). 2022. Notes
from Meeting with BKT--April 9, 2021 (DCN SE10253).
\52\ ERG. 2019. Sanitized_Saltworks Vendor Meeting Notes--Final
(DCN SE07089); U.S. EPA (Environmental Protection Agency). 2022.
Notes from Vendor Call with Heartland on October 19, 2021. September
26 (DCN SE10291).
\53\ U.S. EPA (Environmental Protection Agency). 2022. Notes
from Meeting with ProChem--April 9, 2021 (DCN SE10254).
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Information in the record indicates that there are many
similarities between the FGD and the non-FGD wastestreams where zero-
discharge systems have been used. In the 2020 rule record, the EPA
discussed that cooling tower blowdown at steam electric power plants
and desalination in oil and gas extraction were examples of where
membrane filtration has been used in full-scale applications for
treating high-TDS wastewaters (high-TDS being a characteristic of FGD
wastewater); 85 FR 64664-64665. The 2020 rule record also established
that mining wastewaters, which are high in gypsum scaling potential
(another characteristic of FGD wastewater), have been successfully
treated with membrane filtration applications. Finally, the 2020 rule
record established that, despite the high variability in ash transport
water (a third characteristic of FGD wastewater), it has been
successfully treated with membrane filtration. This information
indicates that membrane filtration can operate effectively on
wastestreams that contain several characteristics of FGD wastewater,
including high TDS, high gypsum scaling potential, and high
variability.\54\ The similarities of other wastewaters to FGD
wastewater are also relevant when considering the successful treatment
by thermal evaporation systems. Thermal evaporation systems have been
used to treat mining wastewaters, oil and gas wastewaters, and landfill
leachate. SDE systems have been used to treat landfill leachate. Thus,
based on the information, the use of zero-discharge systems on other
wastestreams supports the Agency's conclusion that the BAT basis of
zero-discharge systems is available for FGD wastewater discharges.
These uses also support the Agency's conclusion that membrane
filtration, thermal evaporation systems, or SDE systems are each
available on their own.
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\54\ Use of membrane filtration has since expanded into
additional applications, treating wastewaters and industries beyond
those where it was used at the time of the 2020 rule (e.g., the food
and beverage and automotive industries).
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For all the foregoing reasons, the EPA finds that the BAT basis of
zero-discharge systems is technologically available for the control of
discharges in FGD wastewater. Steam electric power plants have used
membrane filtration systems to achieve zero discharge of FGD wastewater
internationally for years, and they have used traditional thermal
evaporation systems \55\ and SDEs \56\ to achieve zero discharge of FGD
wastewater domestically and internationally for years, as even recent
electric utility reports acknowledge.<SUP>57 58 59 60</SUP> The
widespread use across a variety of configurations of zero-discharge
systems, when supplemented with the successful domestic and
international pilot tests and use of such systems on other wastewaters
in many industries (including the steam electric power generating
industry itself and including wastewaters with characteristics that are
similar to the FGD wastestream), further supports EPA's conclusion that
the suite of zero-discharge technologies identified as the BAT basis in
this rule is available. While this is not necessary to support its
prior availability determination, the EPA further finds that any one of
the technologies making up the BAT basis for FGD wastewater is
available as that term is used in the Act. For membrane filtration,
availability is demonstrated through full-scale use of membrane
filtration abroad and in pilot projects both domestically and abroad,
as well as its application to other wastestreams. For thermal
evaporation, availability is demonstrated through use of full-scale
thermal evaporation systems domestically and abroad and pilot projects
both domestic and abroad, as well as their application to other
wastestreams. For SDE systems, availability is demonstrated through use
of full-scale SDE systems domestically and abroad, as well as their use
in at least one known pilot project and application to a non-FGD
wastestream.
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\55\ The Italian thermal evaporation systems discussed first in
the 2013 proposed rule have been in operation for over a decade.
\56\ Spray dry absorbers, effectively the same technology as the
SDE, have been in use for decades to capture the same pollutants
present in FGD wastewater.
\57\ ``Proven technology (considered BAT for new sources by
EPA). 3+ U.S. installations and 6+ European installations by
Aquatech'' (DCN SE07206).
\58\ DCN SE10234.
\59\ DCN SE09998.
\60\ EPRI (Electric Power Research Institute). 2017. Thermal
Evaporation Technologies for Treating Power Plant Wastewater: A
Review of Six Technologies. 000000003002011665 (DCN SE06971).
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Reliance interests in connection with 2020 BAT technologies.
Several commenters on the 2023 proposal criticized EPA for continuing
to support implementation of the 2020 rule while simultaneously
revising that rule with potentially more stringent limitations. These
commenters stated that utilities relied upon materials announcing the
Agency's decision to reconsider the 2020 rule and statements in the
2023 proposal which both confirmed that utilities should continue to
implement the 2020 rule. Thus, in reliance, utilities claimed that they
have continued to install compliant technologies and that such reliance
should lead the EPA to a decision not to finalize more stringent BAT
for these wastewaters. In the
[[Page 40219]]
alternative, some commenters recommended that such facilities reliance
on, and compliance with, the 2020 rule should lead the EPA to build in
additional flexibility for any more stringent BAT. Suggested
flexibilities focused on subcategorization or longer timeframes for
cost recovery before installation of more stringent technologies.
The EPA agrees that such reliance interests should be
considered.\61\ The EPA disagrees, however, with commenters who
suggested these interests mean the Agency must retain only the 2020
limitations in all cases. First, no NPDES permittee has certainty of
its limitations beyond its five-year NPDES permit term, as reissued
permits must incorporate any newly promulgated technology-based
limitations as well as potentially more stringent limitations necessary
to achieve water quality standards. See 40 CFR 122.44(a) and (d). The
statute is designed for both technology-based and water quality-based
effluent limitations to be revisited in each permit and, when
necessary, revised consistent with these provisions and in light of the
goal of ultimately eliminating pollutant discharges from point sources
into WOTUS. See CWA section 101, 33 U.S.C. 1251.
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\61\ The Supreme Court has held that, while an agency may change
policies based upon a reasoned explanation, where a prior policy has
engendered serious reliance interests, those interests must be taken
into account. FCC v. Fox Television Stations, Inc., 556 U.S. at 515
(citation omitted).
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Moreover, the EPA has included enough time for facilities to build
in any reasonable reliance interest. As discussed in section VII.E of
this preamble, the Agency is finalizing a ``no later than'' date for
the new FGD wastewater BAT limitations of December 31, 2029. Having a
``no later than'' date approximately five-and-a-half years following
promulgation allows facilities to rely on permitted limitations for the
remainder of any permit existing as of the effective date of this final
rule.
Third, the EPA has considered the arguments that facilities have
unrecoverable costs, particularly for biological treatment systems that
the final rule may render obsolete, by evaluating both the existing
costs of the 2020 rule and the costs of this final rule together in the
IPM analysis. As discussed in sections VII.F and VIII.C, the EPA uses
IPM to analyze electric sector impacts.\62\ IPM shows small impacts
across the industry and leads the EPA to the conclusion that even the
cumulative cost of the two technologies is economically achievable
(this concept is explained in section VII.F of this preamble). Where
more stringent technologies are available, are economically achievable,
and have acceptable non-water quality environmental impacts as zero-
discharge systems do here, the fact that facilities may have to spend
more to supplement or replace existing treatment systems, even
relatively new ones, is not a sufficient reason on its own to reject
selection of the technology.
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\62\ While this modeling illustrates how the sector may comply
with the rule, the EPA notes that the rule does not require any
facilities to close.
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Lastly, to the extent that the facilities claiming to be most
impacted by having to add treatment are those that will be permanently
ceasing coal combustion by 2034, the EPA has created a new subcategory
for these facilities that would allow them to continue to meet only the
2020 BAT limitations and thereby avoid recovering the costs of two
treatment systems (i.e., biological treatment and a zero-discharge
system), each one designed to meet the requirements of the 2020 or 2024
rules, over the facility's short remaining useful life. EPA anticipates
that approximately nine EGUs may be able to avail themselves of this
subcategory with respect to FGD wastewater.\63\
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\63\ Additional EGUs are projected to participate in this
subcategory for BA transport water and CRL as discussed in the
sections below.
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Economic achievability of zero-discharge systems. The EPA finds
that the costs of zero-discharge systems for control of FGD wastewater
are economically achievable. The 2020 rule cited the increased cost of
membrane filtration as compared to the selected technology basis as a
reason for rejecting membrane filtration \64\ but did not find that the
costs of membrane filtration were not economically achievable at that
time. The EPA also declined in the 2020 rule to establish BAT based on
thermal evaporation systems, which the Agency stated were 2.4 times the
costs of the 2020 BAT technology basis of chemical precipitation plus
low-residence-time-reduction biological treatment and 1.04 times the
cost of membrane filtration. The Agency said that these costs were
unreasonably high, and it cited this finding, together with the costs
that the industry was facing due to other EPA rules, to reject thermal
technologies as not economically achievable.
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\64\ While the relative costs of technologies differ from plant
to plant, the 2020 rule acknowledged, and additional information
obtained during the 2022 information collection confirms, that, in
some cases, technologies such as membrane filtration may be less
costly than biological treatment at individual plants even where, on
average, they would be more expensive to the industry as a whole.
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After updating the cost analysis and IPM modeling for the final
rule, the EPA finds that the costs of the BAT basis of zero-discharge
systems for FGD wastewater are economically achievable for the
industry, as discussed further below and in sections VII.F and VIII.
Furthermore, the EPA notes that the estimates in IPM are conservative
with respect to FGD wastewater. To the extent that costs would have
been lower at six plants had the EPA used certain CBI costs for thermal
evaporation systems in its primary cost analysis, the economic impacts
modeled in IPM at these plants are overestimated.\65\
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\65\ To the extent that cost estimates for individual
technologies are roughly of the same magnitude as indicated in the
primary cost analysis, these costs would not be expected to alter
the findings on economic achievability, even if the Agency were to
rely on any one of the zero-discharge technologies as a standalone
BAT basis.
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Non-water quality environmental impacts of zero-discharge systems.
The EPA finds that the non-water quality environmental impacts of zero-
discharge systems are acceptable.
The EPA proposed to find that the non-water quality environmental
impacts of membrane filtration are acceptable. Specifically, the EPA
proposed to reverse findings from the 2020 rule regarding FA use to
encapsulate the brine generated by membrane filtration. The EPA also
solicited comment on the non-water quality environmental impacts of
other zero-discharge systems that might be used as a BAT technology
basis.
Some commenters raised concerns relating to the non-water quality
environmental impacts of zero-discharge systems. Specifically,
commenters expressed concerns that the EPA had incorrectly evaluated FA
availability because it did not use the most recent EIA data (which
demonstrates that there is not enough FA available for brine
encapsulation), did not use proper brine generation and encapsulation
blending rates, and did not account for the costs of lost FA sales.
Other commenters questioned the technological availability of one
method of handling the solid waste generated from zero-discharge
technologies--brine encapsulation--claiming that it has not been
demonstrated to adequately retain pollutants in a landfill and,
furthermore, that a particular form of brine encapsulation (paste
encapsulation) has not been demonstrated and may not satisfy current
disposal requirements. Finally, commenters claimed that pollutants in
encapsulated brines and unencapsulated salt crystals could be
[[Page 40220]]
remobilized in a landfill setting or could damage the landfill-liner
system. While some comments argued these disposal issues spoke to
availability of the zero-discharge technology, the EPA views this
rather as a non-water quality environmental impact (solid waste
disposal issue) that it must consider. After considering these comments
and the record, the EPA finds that the non-water quality environmental
impacts of zero-discharge systems are acceptable.
With respect to comments on FA availability, the EPA agrees with
commenters that it should evaluate the most recent EIA data, brine
generation data, and data on encapsulation blends. Therefore, the EPA
has updated its analysis to consider the most recent information in
2024 Steam Electric Supplemental Final Rule: Fly Ash Analysis (DCN
SE11692). As noted in that document, FA sold for beneficial use
fluctuates from year-to-year, but over the last five years the amount
sold would still be less than the amount available for sale even after
assuming that every plant uses FA to encapsulate brine from an FGD
wastewater and/or CRL treatment system. Thus, the EPA does not expect
that under worst-case scenarios the use of FA to encapsulate brine
would hamper the fly ash sales market, let alone constitute an
unacceptable non-water quality environmental impact.
Furthermore, the assumption that all facilities use membrane
filtration and generate a brine for encapsulation represents a
conservative estimate on FA usage. The EPA has updated its cost
estimates as discussed in section VIII and section 5 of the TDD. These
revised cost estimates consist of least-cost analysis across the
various zero-discharge systems. Part of this update also included
adjustments to better account for the amount of FA available for
encapsulation, brine generation rates, and brine encapsulation blends,
all to respond to commenters and improve the accuracy of the Agency's
analysis. The EPA finds that the now higher costs of membrane
filtration lead thermal and SDE systems to be a less costly option at
many plants. This finding is consistent with cost information received
from some companies showing that membrane filtration would not be the
least-cost technology. As a result of this analysis selecting non-
membrane systems at a number of plants, the assumptions of FA usage
presented above can be seen as a likely worst-case scenario. To the
extent that FA sales would be even less hampered than the scenario
already found to be acceptable above, it would only further support the
Agency's conclusion that FA use in brine encapsulation has acceptable
non-water quality environmental impacts. For a further discussion of
EPA's revised cost estimates, see section 5 of the TDD.
With respect to comments about potential remobilization of
pollutants from brine encapsulation and demonstration of paste
encapsulation; as far back as the 2015 rule, the EPA pointed to
multiple waste-handling alternatives that were being employed by
facilities with zero-discharge systems. Some facilities at that time
used the brine generated by thermal systems to condition ash for
disposal. In the 2020 rule record, the EPA discussed facilities that
directly engage in FA fixation of the FGD wastewater for this purpose,
skipping the volume reduction step that a membrane or thermal system
would offer (see section 4.1.5 of the 2020 TDD, DCN SE08650). When
commenters express concern that contaminants from encapsulated brines
could be remobilized, these comments assume less processing than EPA
contemplates. The commenters reference situations where FGD wastewater
or brine are merely used to condition ash without employing the further
pozzolanic reactions that the EPA expects to occur in the full
encapsulation process and that EPA included in its cost estimates of
zero discharge. Encapsulation studies demonstrate that concentrations
of leachate pass leachate toxicity tests and are of lower concentration
than raw FGD wastewater. Encapsulation would also result in far less
remobilization than exiting ash conditioning practices. Furthermore, to
the extent that the EPA considered and discussed paste encapsulation,
it was as a potentially cost-saving alternative to these conditioning
and encapsulation techniques that are already well-demonstrated. Thus,
to the extent that it is a less costly solid waste management
alternative, it only provides the promise of cost savings compared to
the EPA's estimates, but the EPA does not rely on this particular form
of brine encapsulation in determining that solid waste disposal issues
as a whole have acceptable non-water quality environmental impacts.
Even if brine encapsulation had not been adequately demonstrated as
a solid waste handling practice, other solid waste handling
alternatives are available. For example, facilities in the 2015 and
2020 rule records took the brine generated from a thermal system all
the way down to a salt crystal using a crystallizer (DCN SE11695). The
EPA evaluated these costs in the FGD Wastewater, CRL, and Legacy
Wastewater Zero Discharge Treatment Technologies Costs, Loadings, and
Non-Water Quality Environmental Impacts file (DCN SE11709) as an
alternative and found it would increase annualized costs by three
percent. These slightly higher overall costs would still be
economically achievable.\66\
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\66\ Facilities could also consider deep-well injection of their
brine. The EPA found that these costs on a nationwide basis would be
three times the costs of encapsulation, and so are unlikely to be
pursued by most facilities, though this too would constitute an
alternative disposal practice available for the management of brine.
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With respect to comments about remobilization of pollutants, the
EPA agrees with commenters that pollutants in a landfill can be
remobilized through percolation of rainwater through the disposed solid
wastes. These solid wastes would include not only any encapsulated
brines but also certain solids and salt crystals that would be disposed
of following use of some thermal and SDE alternatives where no brine is
generated. Here, absent the pozzolanic reactions from either ash
conditioning or encapsulation, remobilization of pollution is more
possible as rainfall percolates through these disposed solids.
Nevertheless, proper landfill management is designed to reduce
infiltration of water through a landfill and to capture leachate that
makes it to the liner at the bottom of a landfill. The EPA received no
comments that the facilities already generating these solids and salts
have failed to properly operate their landfills such that contaminants
were remobilized into the environment. Even where remobilization can
reduce the overall effectiveness of the pollution treatment systems, as
discussed in section VII.B.3 of this preamble, the EPA is also
finalizing zero-discharge limitations for CRL during the life of the
plant, unless they are discharges of unmanaged CRL.\67\ This is
designed to further ensure that these pollutants are kept in the
landfill to the maximum extent possible rather than remobilized and
released into the environment.
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\67\ Note that the EPA is finalizing zero-discharge limitations
for CRL, except as specified in the subcategories discussed in
sections VII.C.4 and C.5. Where lined WMUs collect and treat CRL to
zero-discharge standards during a facility's operation, permeate and
distillate can be used to condition CCR for disposal in these WMUs.
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Many of the facilities presented in the record as having zero-
discharge systems have also successfully disposed of conditioned ash or
FGD solids in landfills for years. The record supports that a properly
designed, installed, and maintained landfill can operate as intended.
As the EPA learned during implementation of the CCR rule, many
[[Page 40221]]
historical CCR landfills may suffer from the lack of an adequate liner
system. However, the Agency has no evidence that, where liners are
properly designed, installed, and maintained, they are incompatible
with the additional pollutants in FGD wastewater that zero-discharge
systems would capture.\68\
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\68\ In contrast, FGD gypsum is already removed from FGD
wastewater before discharge and is known to loosen clay soils which
sometimes form the base of older landfills designed without
composite liners.
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Finally, the EPA finds that, even to the extent that there are any
negative non-water quality environmental impacts, the positive non-
water quality environmental impacts outweigh the negative ones. In
particular, the EPA estimates that there are significant decreases in
air pollution and water withdrawals \69\ as a result of this rule.
While the rule is not being promulgated to reduce these impacts, these
resulting non-water quality environmental impacts further support the
Agency's conclusion that zero-discharge systems for FGD wastewater are
BAT.
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\69\ Reduced water withdrawals could also lead to reduced
impingement and entrainment.
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b. The EPA rejects less stringent technologies than zero-discharge
systems as BAT for FGD wastewater.
Except for the new permanent cessation of coal combustion by 2034
subcategory discussed in section VII.C.4 of this preamble, and for
discharges before the applicability dates of the new zero discharge-
requirements in this final rule, the EPA is not selecting chemical
precipitation followed by a low hydraulic residence time biological
treatment including ultrafiltration, as the BAT technology basis. BAT
is the ``gold standard'' for controlling water pollution from existing
sources, and the Supreme Court has explained that BAT must achieve
``reasonable further progress'' toward the CWA's goal of eliminating
pollution. See Southwestern Elec. Power Co. v. EPA, 920 F.3d at 1003,
1006 (citing Nat'l Crushed Stone v. EPA, 449 U.S. 64, 75 (1980)). The
record shows that the 2020 rule industrywide BAT technology basis for
FGD wastewater removes fewer pollutants than the zero-discharge BAT
technology basis identified in this final rule that has been found to
be technologically available, be economically achievable and have
acceptable non-water quality environmental impacts.\70\ Similarly,
except for the permanent cessation of coal combustion by 2028
subcategory discussed in section VII.C.3 of this preamble, the EPA is
not identifying the less stringent (and previously rejected in the 2015
and 2020 rules) technologies of surface impoundments or chemical
precipitation, as these technologies too will remove fewer pollutants
than the BAT technology basis in this rule.
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\70\ In contrast, nothing in the record or public comments
indicates that chemical precipitation plus low hydraulic residence
time biological reduction has ceased to be available, be
economically achievable, and have acceptable non-water quality
environmental impacts for discharges before the applicability dates
of the new, more stringent limitations of this rule.
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2. BA Transport Water
The EPA is identifying the zero-discharge systems of dry-handling
or closed-loop systems as the technology basis for establishing BAT
limitations to control pollutants discharged in BA transport water.\71\
Specifically, dry-handling systems include both waterless air-cooled
conveyor systems and pneumatic systems, as well as under-boiler
mechanical drag systems (e.g., submerged chain conveyors) and submerged
grind conveyors (e.g., compact submerged conveyors), which use quench
water to cool the ash but immediately remove the ash without generating
BA transport water. Closed-loop systems consist of remote mechanical
drag systems that actively sluice the ash (i.e., transport the ash with
water) and are paired with any necessary storage tanks, chemical
addition systems, and/or RO treatment necessary to fully recycle BA
transport water except during high intensity, infrequent storm events
as discussed below.\72\ The EPA finds that these technologies are
technologically available, are economically achievable, and have
acceptable non-water quality environmental impacts after evaluating the
factors specified in CWA section 304(b)(2)(B).
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\71\ As described in section VII.B.5 of this preamble, the EPA
is also finalizing a definitional change to certain wastewaters,
including BA transport water, that excludes discharges necessary as
a result of high intensity, infrequent storm events, as well as
wastewater removed from ash handling equipment within the first 120
days of decommissioning the equipment.
\72\ In addition to remote MDSs, non-BAT technologies include
many dewatering bins (also known as hydrobins), and surface
impoundments may also have the flexibility to operate as closed-loop
systems. Like remote MDSs, the latter systems may need to install
chemical addition systems (acid, caustic, and/or flocculants), RO
systems, and/or additional storage tanks to operate as fully closed
loop.
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In the 2020 rule, the EPA rejected dry-handling or closed-loop
systems as the BAT technology basis in favor of high-recycle-rate
systems with a site-specific purge allowance of up to 10 percent of the
BA transport water system's volume to address four potential purge
needs.\73\ The EPA justified this change in BAT due to process changes
plants were making to comply with the CCR regulations, as well as the
additional costs of dry-handling or closed-loop systems. In the 2023
proposal, the EPA reevaluated the four asserted purge needs relied upon
in establishing the 2020 purge, and for each asserted purge need, the
Agency explained why the record no longer supported that these purges
should be part of the BAT technology basis. As a result, the EPA
proposed returning to the dry-handling or closed-loop systems that
served as the BAT technology basis in the 2015 rule.
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\73\ The four asserted purge needs related to precipitation,
maintenance, water chemistry, and water balance.
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The EPA received comments both supporting and criticizing the
proposed return to the BAT basis of dry-handling or closed-loop systems
selected in the 2015 rule. Comments supporting the EPA's proposal to
return to the 2015 BAT technology basis for BA transport water focused
on the lack of evidence in the record of facilities with a demonstrated
need to purge BA transport water. These comments also focused on the
legal standard that BAT represents the best performing plant, arguing
further that the EPA has never disputed that the best performing plant
can achieve zero discharge. Comments opposing the return to the 2015
rule standard reiterated the four potential purge needs discussed in
the 2020 rule. In the alternative, these commenters asked the EPA to
formulate flexibilities for purges that in practice might be more or
less flexible than the site-specific 10 percent volumetric purge
allowance arrived at in the 2020 rule.
Commenters also responded to the EPA's solicitation about the
potential disparity between the purges from closed-loop systems and the
purges from under-boiler ``dry'' handling systems that still use quench
water. These comments asked EPA not to further regulate quench water
from under-boiler systems because the water is not used to transport
ash and these facilities had relied on the quench water from dry-
handling systems being treated as a ``low volume waste source'' rather
than BA transport water.
After considering all public comments and the EPA's extensive
record in light of the statutory factors, and as explained below, the
EPA finds that dry-handling or closed-loop systems are available and
economically achievable, and that they have acceptable non-water
quality environmental impacts. Therefore, the
[[Page 40222]]
EPA is selecting dry-handling or closed-loop systems as the BAT
technology basis for BA transport water but is retaining the 2020 rule
limitations for discharges before the applicability dates of the new
zero-discharge requirement.
In the first subsection immediately below, the EPA discusses its
rationale for selecting dry-handling or closed-loop systems as the BAT
technology basis for BA transport water. In the following subsection,
the EPA explains why it is not selecting less stringent technologies
than dry-handling or closed-loop systems as the BAT technology basis
for BA transport water. In the final subsection, the EPA discusses the
definition of BA transport water and why, in light of the record, it
declines to change how under-boiler ``dry'' systems with a discharge
are regulated. For further discussion of the definitional changes to BA
transport water that are being finalized with respect to high
intensity, infrequent storm events, as well as decommissioning
wastewater, see section VII.B.5 of this preamble. For further
discussion of the EPA's retention of the 2020 rule limitations as
interim limitations, see section VII.C.7 of this preamble.
a. The EPA selects dry-handling or closed-loop systems as BAT for
BA transport water.
Technological availability of dry-handling or closed-loop systems.
Based on the record, the EPA finds that dry-handling or closed-loop
systems are technologically available. At the time of the 2020 rule,
the EPA estimated that more than 75 percent of plants already employed
dry-handling systems or wet-sluicing systems in a closed-loop manner,
or they had announced plans to switch to such systems soon. Some of
these systems have been in use since the 1970s, and today, most
facilities have installed one or more such systems.\74\ The high
percentage of plants employing these systems indicates that they are
technologically available.
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\74\ One vendor estimates that only seven ash conversions remain
in the entire industry.
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In the 2015 and 2020 rule preambles, the EPA discussed the
widespread use of dry-handling systems for control of BA transport
water servicing about 200 EGUs at over 100 plants. In the 2020 rule,
the EPA also discussed advances in dry BA handling systems.
Specifically, the Agency discussed a newer technology called submerged
grind conveyors (one example of which is called a compact submerged
conveyor). At the time, compact submerged conveyors were known to be
installed and in operation at two plants. The EPA has since learned
that an additional plant has installed compact submerged
conveyors.<SUP>75 76</SUP> In addition to the increased use of compact
submerged conveyors, a higher number and broader array of dry-handling
systems are currently in place than the EPA originally forecasted. For
example, as indicated in the 2020 rule record, one utility commented
that it had space constraints at a facility that would preclude the
installation of a compact submerged conveyor, and the EPA thus
projected that this facility would employ a high recycle rate system
under the 2020 rule. After the 2020 rule, however, that utility
ultimately installed a different dry-handling system--which highlights
the broad array of dry-handling options available for coal-fired power
plants, regardless of their configuration. Even where space constraints
may prohibit certain dry systems, a plant could use a pneumatic system,
albeit at a somewhat greater cost. The 2020 rule record included
information on 50 pneumatic installations from as early as 1992. Given
that BAT is to reflect the best performing plant in the field,
Kennecott v. EPA, 780 F.2d at 447, and that the facts in the record
support the use of dry-handling technology to achieve zero discharge of
BA transport water, it is likely the EPA could have selected dry-
handling systems as the sole technology basis for control of BA
transport water. Nonetheless, as it did in the 2015 rule, the EPA is
also identifying closed-loop systems as a BAT technology basis for
controlling discharges of BA transport water, given that a limited
number of plants may find that option to be more attractive due to
space constraints and lower costs when compared to a pneumatic system.
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\75\ Some utilities have even suggested that the discussion of
compact submerged conveyors in the final 2020 rule preamble and
additional compliance timeframes have led them to consider these
newer dry systems rather than a previously contemplated high-
recycle-rate/closed-loop system.
\76\ Final Burns & McDonnell Meeting Notes (DCN SE10248).
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After the 2015 rule and during the 2020 rulemaking, certain
industry representatives argued that there are challenges to operating
a closed-loop BA handling system in a truly zero-discharge manner. They
argued that closed-loop systems, including remote MDS and dewatering
bins, cannot maintain fully closed-loop operations due to chemistry
issues or water imbalances in the system, such as those that might
occur from unexpected maintenance or large precipitation events. Even
accounting for these issues, however, the 2020 rule did not find that
closed-loop systems are not technologically available. Information in
the EPA's 2020 rule record indicated that plants can operate their
closed-loop systems to achieve zero discharge, although this could
require some process changes and their resulting costs. Instead, the
Agency rejected this technology as a basis for BAT based process
changes happening at plants to comply with the CCR regulations
(addressed further below), while also noting the additional costs over
the 2015 rule's estimates. As explained below, the record indicates
that closed-loop BAT handling systems are economically achievable. See
section VIII of this preamble for a further discussion of costs
associated with the closed-loop system technology basis.
In the 2020 rule, the EPA discussed four potential challenges with
maintaining closed-loop systems: (1) managing non-BA transport water
inflows, (2) managing precipitation-related inflows, (3) managing
unexpected maintenance events, and (4) maintaining water system
chemistry. The 2023 proposal discussed these issues at length,
including why EPA did not view them as a basis for rejecting zero-
discharge requirements. As explained in the proposal and further
discussed below, based on the current record, the EPA continues to view
none of these previously discussed challenges as providing a basis for
rejecting closed-loop systems as not technologically available,
although these issues may in certain circumstances require a plant to
incur additional costs (which are found to be economically achievable)
or to have an infrequent precipitation-related discharge (which would
be addressed by the definitional changes the EPA is finalizing in this
rule).
First, in 2020, the EPA stated that managing non-BA transport water
inflows had the potential to result in water imbalances within a
closed-loop system. In the 2023 proposal, the EPA found that closed-
loop systems can be sized to handle additional wastestreams. The EPA
received comments reiterating the 2020 rule findings; however, none of
these comments provided specific data or information demonstrating that
even one system cannot handle non-BA transport water inflows. Thus, EPA
is maintaining its finding from proposal that a purge in response to
water imbalance due to management of other wastestreams is not
necessary.
Second, in 2020, EPA stated that managing precipitation-related
inflows had the potential to result in water imbalances in the BA
handling system. At proposal, EPA found that precipitation-related
inflows can be
[[Page 40223]]
adequately managed with design improvements, including the use of
roofing where appropriate. The 2015 BAT technology basis and 2020 rule
remote MDS technology designs included covers to avoid collecting
precipitation, and the costs for covers were included in the associated
cost analysis. The EPA received comments on the 2023 proposal
reiterating the 2020 rule findings; however, none of these comments
provided specific data or information demonstrating that even one
system cannot handle common precipitation-related inflows.\77\ To the
extent that a plant experiences precipitation-related inflows as a
result of a 10-year storm event of 24-hour or longer duration (e.g., a
10-year, 30-day storm event), the EPA is finalizing a definitional
change discussed in section VII.B.5 of this preamble.
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\77\ In one comment, a utility suggested that it could not
employ roofing at its plant without jeopardizing the necessary
cooling of the BA, but this plant did not provide any data showing
that it could not manage this heat transfer with standard heating,
ventilation, and air conditioning (HVAC) equipment.
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The 2020 rule mentioned a third previously discussed challenge to
operating a remote MDS as a closed-loop system: the possibility of
infrequent maintenance events that might fall outside the 2015 rule
exclusion of ``minor maintenance'' and ``leaks'' from the definition of
BA transport water. EPRI <SUP>78 79</SUP> listed several such
maintenance events; most were expected to occur less than annually.
EPRI provided information about the estimated frequency and volume of
water associated with each maintenance event; however, EPRI did not
provide information about a specific remote MDS unable to manage these
maintenance events with existing maintenance tanks. In the 2023
proposal, the EPA found that maintenance could be managed within a
closed-loop system. Furthermore, even where maintenance wastewater
volumes are too large to be managed in existing maintenance tanks,
utilities can, at additional cost, lease storage tanks for short-term
maintenance where these infrequent maintenance events are foreseeable.
Commenters did not provide any information on maintenance activities
that would require a purge if facilities properly planned and executed
regular operation and maintenance (O&M). Thus, the EPA is maintaining
its finding from proposal that a purge of BA transport water for
maintenance is not necessary.
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\78\ EPRI, 2018. Closed-Loop Bottom Ash Transport Water: Costs
and Benefits to Managing Purges (DCN SE06920).
\79\ EPRI, 2016. Guidance Document for Management of Closed-Loop
Bottom Ash Handling Water in Compliance with the 2015 Effluent
Limitations Guidelines (DCN SE06963).
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The final engineering challenge discussed in the 2020 rule record
with respect to closed-loop systems was the need to maintain water
system chemistry. The 2020 rule discussed potentially problematic
system chemistries, such as extreme acidic conditions, high scaling
potential, and the buildup of fine particulates that could clog pumps
and other equipment. The 2015 closed-loop system BAT design basis
included a chemical addition system to manage these system chemistries,
as does the BAT basis in this final rule. In particular, corrosivity
can be managed through pH adjustment, scaling can be managed with acid
and/or antiscalants, and fines can be further settled out with polymers
and other coagulants. EPRI has documented that some systems have gone
slightly further, pairing the chemical addition systems with changes in
operations, such as higher flow rates or longer contact time. Some
commenters on the 2023 proposal suggested that systems would not be
able to manage these chemistry problems but did not provide information
supporting this assertion. In the absence of information, the EPA finds
that, even assuming that the previously mentioned strategies would not
apply at a given plant, the same slipstream of purge allowed under the
2020 rule could be treated with RO and recycled back in as clean makeup
water. The EPA has considered these additional costs as discussed in
sections VII.F and VIII, and outside the additional cost (which is
found to be economically achievable), there is no record evidence that
this chemistry-related challenge cannot be overcome with reasonable
steps. Therefore, this concern does not provide a basis for rejecting
closed-loop systems as BAT.
For all the foregoing reasons, the EPA finds that the record
indicates that dry-handling or closed-loop systems are technologically
available for control of discharges in BA transport water.
Economic achievability of dry-handling or closed-loop systems. The
EPA finds that the costs of dry-handling or closed-loop systems are
economically achievable. In the 2020 rule, the EPA cited the costs of
closed-loop systems as an additional basis for selecting high recycle
rate systems. In the 2020 rule, the EPA noted that it had
``conservatively'' estimated costs of $63 million per year based on all
facilities using a remote MDS needing a 10 percent purge to be treated
with RO in order to achieve complete recycle (i.e., zero discharge
operations). The EPA never found, however, that the additional costs to
achieve zero discharge were not economically achievable.
The EPA's updated cost estimates demonstrate that, after including
the costs of treating all wastestreams--including achieving zero
discharge for BA transport water--the final rule would result in
minimal economic impacts. (For further information, see sections VII.F
and VIII.) After considering these results, the EPA finds that these
additional costs are economically achievable as that term is used in
the CWA.
Non-water quality environmental impacts of dry-handling or closed-
loop systems. The EPA finds that the non-water quality environmental
impacts associated with dry-handling or closed-loop systems for
controlling BA transport water discharges are acceptable. See sections
VII.G and X below for more details.
Process changes associated with dry-handling or closed-loop
systems. In the 2020 rule, the EPA also rejected dry handling or
closed-loop systems due to process changes happening at steam electric
facilities as they moved toward compliance with the CCR regulations.
The EPA stated that, as plants close their surface impoundments under
the CCR regulations, they may choose to send certain non-CCR
wastewaters to their BA handling system. This was said to potentially
complicate their efforts to fully close their BA handling systems due
to increased scaling, corrosivity, or plugging of equipment.
Alternatively, a closed-loop requirement might incentivize plants to
discharge their non-CCR wastes rather than send them to their BA
handling systems for control, in which case they would be subject to
less stringent requirements governing low volume waste sources. The EPA
also suggested that requiring limitations based on closed-loop systems
could result in plants using their surface impoundments longer,
assuming plants cannot build alternative storage capacity and need to
continue to send their non-CCR wastes to unlined impoundments.
The rationale in the 2020 rule is no longer persuasive as a reason
to select high recycle rate systems rather than dry-handling or closed-
loop systems because the changes happening at plants under the CCR
regulations are expected to be complete by the time the final BAT
limitations apply to any given plant. In particular, the final rule BA
transport water requirements will be included in NPDES permits with an
applicability date of no later than December 31, 2029. This is over a
decade after the
[[Page 40224]]
promulgation of the 2015 CCR rule and eight years after even the
revised CCR surface impoundment deadline of April 11, 2021, by which
facilities were required to cease receipt of all wastes into their
unlined CCR surface impoundment.\80\ As of the publication of this
rule, most facilities have already completed conversions of their
leaking, unlined CCR surface impoundments under the CCR regulations,
which means that they no longer rely on these unlined surface
impoundments as part of their BA handling systems, but rather have
installed systems to handle their BA transport water that do not rely
on unlined CCR surface impoundments.\81\
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\80\ 40 CFR 257.101(a)(1).
\81\ See, e.g., <a href="https://www.epa.gov/coalash/coal-combustion-residuals-ccr-part-implementation">https://www.epa.gov/coalash/coal-combustion-residuals-ccr-part-implementation</a>.
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Of the remaining unlined CCR surface impoundments that might exist
following promulgation of this rule, those operating under the CCR Part
A rule flexibility found in Sec. 257.103(f)(2) must permanently cease
coal combustion, and as discussed below, the EPA is retaining the
subcategory for EGUs permanently ceasing coal combustion by 2028, which
does not require zero discharge of BA transport water. For those
unlined CCR surface impoundments that are not permanently ceasing coal
combustion and are required to close for cause but where alternative
capacity is technically infeasible, there is some flexibility under the
CCR Part A rule allowing for a maximum timeframe of October 15, 2023,
or October 15, 2024, for the surface impoundment to cease receipt of
waste.\82\ The 2023 and 2024 extended timeframes require EPA
approval.\83\ Even with these extensions, the majority of facilities
will have ceased receipt of waste in its non-compliant surface
impoundment and completed its conversion to a CCR regulation-compliant
BA handling method (necessary to remain in operation) within a few
months of the effective date of this rule. Since there are no looming
deadlines and tight timeframes under the CCR regulations that would
justify continued flexibility, facilities with high recycle rate
systems are free to focus on transitioning those high recycle rate
systems to closed-loop operations.\84\ Because ash handling changes
will no longer be compelled by the CCR regulations by the time this
final rule is effective, the EPA concludes that there are no ``process
change'' or non-water quality environmental impact reasons related to
the CCR regulations that weigh against the EPA's decision to select
dry-handling or closed-loop systems as the BAT basis for control of BA
transport water discharges.
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\82\ 40 CFR 257.103(f)(1)(vi).
\83\ Further information on the implementation of these Part A
applications is available on EPA's website at: <a href="https://www.epa.gov/coalash/coal-combustion-residuals-ccr-part-implementation">https://www.epa.gov/coalash/coal-combustion-residuals-ccr-part-implementation</a>.
\84\ Although the EPA estimates that fully closing the loop
would be less expensive than converting to a dry-handling system,
nothing would preclude a facility with a high recycle rate system
from installing one of the technologically available and
economically achievable dry-handling systems.
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b. The EPA rejects less stringent technologies than dry-handling or
closed-loop systems as BAT for BA transport water.
Except for the new subcategory for EGUs permanently ceasing coal
combustion by December 31, 2034, and for discharges before the
applicability dates for the new zero-discharge requirement of this
rule, the EPA is not establishing BAT limitations based on high recycle
rate systems. In the 2020 rule, the EPA reversed its decision from the
2015 rule and determined that dry-handling or closed-loop systems were
not BAT. As a result, the EPA established a volumetric purge allowance
(with a maximum of 10 percent of the system volume) to be determined on
a case-by-case basis by the permitting authority, which required a
permitting authority's BPJ analysis to determine any appropriate
further control. As discussed above, the technological issues
identified in the 2020 rule can be resolved, albeit at potentially
additional costs, which the EPA finds are economically achievable.
Furthermore, a dewatering bin or remote MDS with a purge removes fewer
pollutants than the BAT basis of dry-handling or closed-loop systems,
which the Agency finds is technologically available, economically
achievable, and has acceptable non-water quality environmental
impacts.\85\ BAT is the ``gold standard'' for controlling water
pollution from existing sources, and the Supreme Court has explained
that BAT must achieve ``reasonable further progress'' toward the Act's
goal of eliminating pollution. See Southwestern Elec. Power Co. v. EPA,
920 F.3d at 1003, 1006 (citing Nat'l Crushed Stone v. EPA, 449 U.S. at
75). For these reasons, the EPA is not selecting high-rate-recycle
systems as BAT.
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\85\ In contrast, nothing in the record or public comments
indicates that high-recycle-rate systems ceased to be available, be
economically achievable, and have acceptable non-water quality
environmental impacts for discharges before the applicability dates
of the new, more stringent limitations of this rule.
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Except for the subcategory for EGUs permanently ceasing coal
combustion by December 31, 2028, the EPA is also not identifying the
less stringent (and previously rejected in the 2015 and 2020 rules)
technology of surface impoundments as the technology basis for BAT, as
this technology would also remove fewer pollutants than the BAT basis
of dry-handling or closed-loop systems, which the EPA finds is
technologically available, is economically achievable, and has
acceptable non-water quality environmental impacts.
c. The EPA continues to regulate discharges from some dry-handling
BA systems as a low volume waste source.
As previously discussed, the final BAT technology basis for BA
transport water is dry-handling or closed-loop systems. This technology
basis incorporates systems that operate so as to not generate BA
transport water at all (so-called ``dry'' systems), as well as systems
that do generate BA transport water but recycle that transport water in
a closed-loop manner so as to achieve no discharge (so-called ``wet''
systems). At proposal
[…truncated; see source link]Indexed from Federal Register on May 9, 2024.
This is legal information, not legal advice. Laws vary by jurisdiction and change frequently. Always verify current law with official sources and consult a licensed attorney in your jurisdiction for advice on your specific situation.