Rule2026-05261
National Emission Standards for Hazardous Air Pollutants: Polyether Polyols Production Industry Review
Primary source
Metadata and text below are from the Federal Register, a public-domain U.S. government work. Always verify the official published version before relying on it for any legal matter.
Published
March 18, 2026
Effective
March 18, 2026
Issuing agencies
Environmental Protection Agency
Abstract
The U.S. Environmental Protection Agency (EPA) is finalizing amendments to the National Emission Standards for Hazardous Air Pollutants (NESHAP) for the Polyether Polyols (PEPO) Production source category ("PEPO NESHAP") under Clean Air Act (CAA) section 112. Specifically, the EPA is finalizing certain ethylene oxide (EtO)- specific standards pursuant to CAA section 112(d)(6) rather than finalizing the proposed second residual risk review and corresponding amendments pursuant to CAA section 112(f)(2). In addition, the EPA is taking final action addressing certain issues raised in an administrative petition for reconsideration. Lastly, the EPA is finalizing maximum achievable control technology (MACT) standards for certain emission points, work practice standards for certain activities where alternatives are appropriate, performance testing requirements once every five years for certain process vents, and electronic reporting requirements for performance test reports, flare management plans, and periodic reports.
Full Text
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<title>Federal Register, Volume 91 Issue 52 (Wednesday, March 18, 2026)</title>
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[Federal Register Volume 91, Number 52 (Wednesday, March 18, 2026)]
[Rules and Regulations]
[Pages 13116-13195]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 2026-05261]
[[Page 13115]]
Vol. 91
Wednesday,
No. 52
March 18, 2026
Part II
Environmental Protection Agency
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40 CFR Part 63
National Emission Standards for Hazardous Air Pollutants: Polyether
Polyols Production Industry Review; Final Rule
Federal Register / Vol. 91 , No. 52 / Wednesday, March 18, 2026 /
Rules and Regulations
[[Page 13116]]
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ENVIRONMENTAL PROTECTION AGENCY
40 CFR Part 63
[EPA-HQ-OAR-2023-0282; FRL-10854-02-OAR]
RIN 2060-AW01
National Emission Standards for Hazardous Air Pollutants:
Polyether Polyols Production Industry Review
AGENCY: Environmental Protection Agency (EPA).
ACTION: Final rule.
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SUMMARY: The U.S. Environmental Protection Agency (EPA) is finalizing
amendments to the National Emission Standards for Hazardous Air
Pollutants (NESHAP) for the Polyether Polyols (PEPO) Production source
category (``PEPO NESHAP'') under Clean Air Act (CAA) section 112.
Specifically, the EPA is finalizing certain ethylene oxide (EtO)-
specific standards pursuant to CAA section 112(d)(6) rather than
finalizing the proposed second residual risk review and corresponding
amendments pursuant to CAA section 112(f)(2). In addition, the EPA is
taking final action addressing certain issues raised in an
administrative petition for reconsideration. Lastly, the EPA is
finalizing maximum achievable control technology (MACT) standards for
certain emission points, work practice standards for certain activities
where alternatives are appropriate, performance testing requirements
once every five years for certain process vents, and electronic
reporting requirements for performance test reports, flare management
plans, and periodic reports.
DATES: This final rule is effective on March 18, 2026. The Director of
the Federal Register (FR) has approved incorporation by reference (IBR)
of certain publications listed in the rule as of March 18, 2026.
ADDRESSES: The EPA established a docket for this action under Docket ID
No. EPA-HQ-OAR-2023-0282. All documents in the docket are listed in
<a href="https://www.regulations.gov/">https://www.regulations.gov/</a>. Although listed, some information is not
publicly available, e.g., Confidential Business Information (CBI) or
other information whose disclosure is restricted by statute. The EPA
does not place certain other material, such as copyrighted material, on
the internet; this material is publicly available only as portable
document format (PDF) versions accessible on EPA computers in the
docket office reading room. The public cannot download certain
databases and physical items from the docket but may request these
items by contacting the docket office at (202) 566-1744. The docket
office has 10 business days to respond to these requests. With the
exception of such material, publicly available docket materials are
available electronically at <a href="https://www.regulations.gov">https://www.regulations.gov</a> or on EPA
computers in the docket office reading room at the EPA Docket Center,
WJC West Building, Room Number 3334, 1301 Constitution Ave. NW,
Washington, DC. The Public Reading Room hours of operation are 8:30
a.m. to 4:30 p.m. Eastern Time (ET), Monday through Friday. The
telephone number for the Public Reading Room is (202) 566-1744, and the
telephone number for the EPA Docket Center is (202) 566-1742.
FOR FURTHER INFORMATION CONTACT: For information about this final rule,
contact U.S. EPA, Attn: Johanna Klein, Mail Drop: Industrial Processing
and Power Division (E143-01), 109 T.W. Alexander Drive, P.O. Box 12055,
Research Triangle Park, North Carolina 27711; telephone number: (919)
541-2283; and email address: <a href="/cdn-cgi/l/email-protection#450e29202c2b6b0f2a2d242b2b24052035246b222a33"><span class="__cf_email__" data-cfemail="fcb790999592d2b693949d92929dbc998c9dd29b938a">[email protected]</span></a>.
SUPPLEMENTARY INFORMATION:
Preamble acronyms and abbreviations. Throughout this notice the use
of ``we,'' ``us,'' or ``our'' refers to the EPA. The Agency uses
multiple acronyms and terms in this preamble. While this list may not
be exhaustive, to ease the reading of this preamble and for reference
purposes, the EPA defines the following terms and acronyms here:
ANSI American National Standards Institute
APCD air pollution control device
ASME American Society of Mechanical Engineers
1-BP 1-bromopropane
CAA Clean Air Act
CDX Central Data Exchange
CEDRI Compliance and Emissions Data Reporting Interface
CEMS continuous emission monitoring system
CFR Code of Federal Regulations
CMPU chemical manufacturing process unit
CO carbon monoxide
CO<INF>2</INF> carbon dioxide
EAV equivalent annualized value
ECO extended cookout
EIA Economic Impacts Analysis
EPA Environmental Protection Agency
ERT Electronic Reporting Tool
EtO Ethylene Oxide
Fe Fraction emitted
kg/yr kilograms per year
HAP hazardous air pollutant(s)
HON Hazardous Organic NESHAP
ICR information collection request
IFR internal floating roof
kPa kilopascals
lb/hr pounds per hour
lb/yr pounds per year
LDAR leak detection and repair
LEAN Louisiana Environmental Action Network
LEL lower explosive limit
m\3\ cubic meters
MACT maximum achievable control technology
MON Miscellaneous Organic Chemical Manufacturing NESHAP
MTVP maximum true vapor pressure
NAICS North American Industry Classification System
NEI National Emissions Inventory
NESHAP national emission standards for hazardous air pollutants
NO<INF>X</INF> nitrogen oxides
NRDC Natural Resources Defense Council
NTTAA National Technology Transfer and Advancement Act
OAR Office of Air and Radiation
OMB Office of Management and Budget
PDF portable document format
PEPO polyether polyol(s)
PMPU polyether polyol manufacturing process unit
ppmv parts per million by volume
ppmw parts per million by weight
PRA Paperwork Reduction Act
psia pounds per square inch absolute
psig pounds per square inch gauge
PRD pressure relief devices
PV present value
RFA Regulatory Flexibility Act
RTR Risk and Technology Review
scmm standard cubic meters per minute
SO<INF>2</INF> sulfur dioxide
THF tetrahydrofuran
TOC total organic compound
tpy tons per year
TRE total resource effectiveness
[mu]g/m\3\ micrograms per cubic meter
UMRA Unfunded Mandates Reform Act
U.S.C. United States Code
VCS voluntary consensus standards
VOC volatile organic compound(s)
Table of Contents
I. General Information
A. Executive Summary
B. Does this action apply to me?
C. What is the statutory authority for this final action?
D. Where can I get a copy of this document and other related
information?
E. Judicial Review and Administrative Reconsideration
F. Severability
II. Background
A. What is the PEPO Production source category, and how does the
NESHAP regulate HAP emissions from the source category?
B. What changes did we propose for the PEPO Production source
category in our December 27, 2024, proposal?
III. What is included in this final rule?
A. What are the final rule amendments based on the second
residual risk review for the PEPO Production source category?
B. What are the final rule amendments based on the technology
review for the PEPO Production source category?
C. What are the final rule amendments we are taking pursuant to
CAA section 112(d)(2) and (3) and 112(h) for the PEPO Production
source category?
[[Page 13117]]
D. What other changes have we made to the NESHAP?
E. What are the effective and compliance dates of the standards?
IV. What is the rationale for our final decisions and amendments for
the PEPO Production source category?
A. Second Residual Risk Review for the PEPO Production Source
Category
B. Technology Review for the PEPO Production Source Category
C. Amendments Pursuant to CAA Section 112(d)(2) and (3) and
112(h) for the PEPO Production Source Category
D. Other Amendments to the PEPO NESHAP
V. Summary of Cost, Environmental, and Economic Impacts and
Additional Analyses Conducted
A. What are the affected facilities?
B. What are the air quality impacts?
C. What are the cost impacts?
D. What are the economic impacts?
E. What are the benefits?
VI. Statutory and Executive Order Reviews
A. Executive Order 12866: Regulatory Planning and Review and
Executive Order 13563: Improving Regulation and Regulatory Review
B. Executive Order 14192: Unleashing Prosperity Through
Deregulation
C. Paperwork Reduction Act (PRA)
D. Regulatory Flexibility Act (RFA)
E. Unfunded Mandates Reform Act (UMRA)
F. Executive Order 13132: Federalism
G. Executive Order 13175: Consultation and Coordination With
Indian Tribal Governments
H. Executive Order 13045: Protection of Children From
Environmental Health Risks and Safety Risks
I. Executive Order 13211: Actions Concerning Regulations That
Significantly Affect Energy Supply, Distribution, or Use
J. National Technology Transfer and Advancement Act (NTTAA) and
1 CFR Part 51
K. Congressional Review Act (CRA)
I. General Information
A. Executive Summary
The EPA promulgated the PEPO NESHAP on June 1, 1999, and codified
the NESHAP at 40 CFR part 63, subpart PPP.\1\ In 2014, the EPA
finalized a technology review and residual risk review (``RTR'') for
the PEPO NESHAP under the provisions of CAA sections 112(d)(6) and
(f)(2); \2\ subsequently, the EPA agreed to reconsider two aspects of
the 2014 rulemaking in response to a petition for reconsideration.
Through these actions, the Agency addressed its statutory obligations
to promulgate MACT standards under CAA section 112(d)(2)-(3), conduct a
residual risk review within eight years of promulgating the MACT
standards under CAA section 112(f)(2), and conduct the first technology
review (which must occur going forward every eight years) under CAA
section 112(d)(6). The Agency concluded in 2014 that further amendments
were not required under the RTR but took the opportunity in the 2014
rulemaking to make certain other amendments to the NESHAP.
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\1\ 64 FR 29420 (June 1, 1999).
\2\ 79 FR 17340 (Mar. 27, 2014).
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On December 27, 2024, in connection with a consent decree
obligation related to the ongoing technology review requirement in CAA
section 112(d)(6), the EPA proposed revisions to the PEPO NESHAP based
on the second technology review and reconsideration issues stemming
from the 2014 rule. Although the Agency had already completed the
residual risk review for this source category in the 2014 RTR, the EPA
also proposed a second, ``discretionary'' residual risk review and
certain amendments based on the results of the proposed review.\3\
Sections II.B.3 and 4 of this preamble describe other revisions that
the EPA proposed for the PEPO NESHAP.
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\3\ 89 FR 105986 (Dec. 27, 2024).
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In this action, the EPA is finalizing decisions and revisions for
the PEPO NESHAP. The EPA summarizes and responds to the more
significant public comments on the proposed rule within this
preamble.\4\ Following the 81-day comment period, the EPA conducted
listening sessions with representatives of PEPO production facilities'
owners and operators through meetings with the American Chemistry
Council, American Fuel and Petrochemical Manufacturers, and Huntsman
Corporation.\5\ Consistent with the EPA Policy on Consultation and
Coordination with Indian Tribes, the EPA offered government-to-
government consultation with Tribes in December 2024.
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\4\ A summary of all other public comments on the proposal and
the EPA's responses to those comments is available in the document
Summary of Public Comments and Responses for National Emission
Standards for Hazardous Air Pollutants for Polyether Polyols
Production Industry, Docket ID No. EPA-HQ-OAR-2023-0282.
\5\ Additional details about these meetings are in the documents
titled Documentation of May 2025 Meetings With Industry
Stakeholders, Documentation of Meetings With Industry Stakeholders--
June through September, and Documentation of Meetings With Industry
Stakeholders--December 2025 through February 2026, Docket ID EPA-HQ-
OAR-2023-0282.
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Specifically, after reviewing public input and considering the
issues further, the EPA agrees with public comments that, instead of
finalizing a second, ``discretionary'' residual risk review and EtO-
specific standards based on that review, it is more appropriate to
evaluate EtO-specific standards under the CAA section 112(d)(6)
requirement to conduct periodic technology reviews and revise standards
``as necessary.'' The EPA is finalizing the proposed EtO-specific
standards (with revisions) for process vents, storage vessels,
equipment leaks, heat exchange systems, and wastewater under CAA
section 112(d)(6) rather than CAA section 112(f)(2). This pathway
satisfies the EPA's obligations under the statute and the applicable
consent decree, provides additional protections for public health, and
reflects the typical approach the Agency has taken to revising
standards after completion of the RTR. To note, the EPA is not
finalizing the proposed fenceline monitoring work practice standard and
the proposed revision to the continuous process vent standard.
Otherwise, the EPA is finalizing provisions as proposed, with some
clarifying changes and technical corrections. A ``track changes''
version of the regulatory language that incorporates the changes in
this action is available in the docket.
B. Does this action apply to me?
Regulated entities. Table 1 of this preamble lists categories and
entities potentially regulated by this action.
Table 1--NESHAP and Industrial Source Categories Affected by This Final
Action
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NAICS \1\
NESHAP and source category code
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40 CFR part 63, subpart PPP, PEPO Production.............. 325199
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\1\ North American Industry Classification System (NAICS).
Table 1 of this preamble, although not exhaustive, provides a guide
for readers regarding entities likely to be affected by the final
action for the source category listed. To determine whether your
facility is affected, you should examine the applicability criteria in
the appropriate NESHAP. If you have any questions regarding the
applicability of any aspect of this NESHAP, please contact the
appropriate person listed in the preceding FOR FURTHER INFORMATION
CONTACT section of this preamble.
C. What is the statutory authority for this final action?
1. NESHAP
The statutory authority for this final action is provided by CAA
section 112, as amended (42 U.S.C. 7412). CAA section 112 establishes a
two-stage regulatory process to develop standards for emissions of
hazardous air pollutant(s) (HAPs) from stationary sources. In the first
stage, the EPA
[[Page 13118]]
promulgates technology-based standards under CAA section 112(d) for
categories of sources identified as emitting one or more of the HAP
listed in CAA section 112(b). ``Major sources'' are those that emit, or
have the potential to emit, any single HAP at a rate of 10 tons per
year (tpy) or more, or 25 tpy or more of any combination of HAP.\6\ For
major sources, these standards are commonly referred to as MACT
standards; CAA section 112(d)(2) provides that these must reflect the
maximum degree of emission reductions of HAP achievable (after
considering cost, energy requirements, and non-air quality health and
environmental impacts). In developing MACT standards, CAA section
112(d)(2) directs the EPA to consider the application of measures,
processes, methods, systems, or techniques, including, but not limited
to, those that reduce the volume of or eliminate HAP emissions through
process changes, substitution of materials, or other modifications;
enclose systems or processes to eliminate emissions; collect, capture,
or treat HAP when released from a process, stack, storage, or fugitive
emissions point; are design, equipment, work practice, or operational
standards; or any combination of the above.
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\6\ 42 U.S.C. 7412(a)(1).
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CAA section 112(d)(3) establishes a minimum control level for MACT
standards, known as the MACT ``floor,'' based on emission controls
achieved in practice by the best performing sources. For new sources,
the MACT floor cannot be less stringent than the emission control
achieved in practice by the best-controlled similar source. The MACT
standards for existing sources can be less stringent than floors for
new sources, but they cannot be less stringent than the average
emission limitation achieved by the best-performing 12 percent of
existing sources in the category or subcategory (or the best-performing
five sources for categories or subcategories with fewer than 30
sources). The EPA also considers control options that are more
stringent than the floor and may establish standards more stringent
than the floor, based on the consideration of the cost of achieving the
emissions reductions, any non-air quality health and environmental
impacts, and energy requirements.\7\ Standards more stringent than the
floor are commonly referred to as ``beyond-the-floor'' standards.
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\7\ Id. 7412(d)(2).
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In the second stage of the regulatory process, the CAA requires the
EPA to undertake two different analyses, which the Agency refers to as
the technology review and the residual risk review. Under the
technology review, the EPA must review the technology-based standards
and revise them ``as necessary (taking into account developments in
practices, processes, and control technologies)'' no less frequently
than every eight years, pursuant to CAA section 112(d)(6). In
conducting this review, the EPA is not required to recalculate the MACT
floors that were established in earlier rulemakings.\8\ The EPA may
consider cost in deciding whether to revise the standards pursuant to
CAA section 112(d)(6).\9\ Pursuant to the D.C. Circuit's decision in
Louisiana Environmental Action Network (LEAN) v. EPA,\10\ the EPA also
reviews available data to determine if there are unregulated emissions
of HAP within the source category and evaluate these data for use in
developing new emission standards. Under the residual risk review,
pursuant to CAA section 112(f), the EPA must within eight years of
promulgating the technology-based standards for a source category
evaluate the risk to public health remaining after application of the
technology-based standards and revise the standards, if necessary, to
provide an ample margin of safety to protect public health or to
prevent, taking into consideration costs, energy, safety, and other
relevant factors, an adverse environmental effect.
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\8\ Ass'n of Battery Recyclers, Inc. v. EPA, 716 F.3d 667 (D.C.
Cir. 2013); Natural Resources Defense Council (NRDC) v. EPA, 529
F.3d 1077, 1084 (D.C. Cir. 2008).
\9\ 42 U.S.C. 7412(d)(2), (6); Ass'n of Battery Recyclers, 716
F.3d at 673-74.
\10\ 955 F.3d 1088 (D.C. Cir. 2020).
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In the proposal published on December 27, 2024, the EPA conducted a
review that included both a technology review, required by CAA section
112(d)(6), and a second residual risk review, which the Agency claimed
was allowed but not required under CAA section 112(f)(2).\11\ Notably,
the EPA's practice prior to 2024 had not involved conducting second,
``discretionary'' risk reviews or promulgating additional standards
based on such a second review when the RTR had already been completed.
As discussed below, the EPA is not finalizing the proposed residual
risk review in this action and is instead finalizing EtO-specific
standards under CAA section 112(d)(6), which authorizes the Agency to
revise standards ``as necessary.'' \12\
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\11\ 89 FR 105986 (Dec. 27, 2024).
\12\ See section IV.A.4 of this preamble for more information.
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2. Petition for Reconsideration
In addition to amendments promulgated under CAA section 112(d)(6),
this final action includes the EPA's response to issues raised in an
administrative petition submitted pursuant to CAA section 307(d)(7)(B)
on certain aspects of the 2014 review of the PEPO NESHAP. In May 2014,
the EPA received a petition for reconsideration of the PEPO NESHAP (40
CFR part 63, subpart PPP), Pesticide Active Ingredient Production
NESHAP (40 CFR part 63, subpart MMM), and Group IV Polymers and Resins
NESHAP (40 CFR part 63, subpart JJJ) pursuant to CAA section
307(d)(7)(B) from the Louisiana Environmental Action Network, Ohio
Valley Environmental Coalition, and Sierra Club, collectively.\13\ For
the PEPO NESHAP, the petitioners requested that the EPA: (1) remove the
affirmative defense provisions from the rules in light of the judicial
opinion in NRDC v. EPA; \14\ (2) provide adequate opportunity to
comment on the requirements associated with emissions from pressure
relief devices (PRDs) (including associated compliance dates, the EPA's
decision to not specifically require electronic indicators and alarms
to monitor PRD releases to the atmosphere, and the standard's
applicability to PRDs in organic HAP service versus PRDs in total HAP
service); (3) redo the risk assessment using updated emission factors;
(4) set additional monitoring requirements for flares to reduce flaring
emissions; (5) set fenceline monitoring requirements; (6) reconsider
its decision not to set standards that account for developments in leak
detection and repair (LDAR); and (7) use existing regulatory authority
to strengthen chemical facility safety and prevent accidents in
accordance with the U.S. Chemical Safety and Hazard Investigation Board
and Executive Order 13650. On August 26, 2014, the EPA sent a letter to
the petitioners informing them that the EPA was granting their request
for reconsideration on issues (1) and (2).\15\ In the letter, the EPA
also stated that it would initiate a notice-and-comment rulemaking on
the issues for which the Agency granted reconsideration. The EPA
addressed issue (1), the removal of affirmative defense provisions
associated with the violation of air emission standards due
[[Page 13119]]
to malfunctions, in a separate rulemaking; therefore, this final rule
does not address that issue.\16\ This action formally responds to the
remaining issues concerning the PEPO NESHAP raised in the petition.\17\
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\13\ A copy of the petition and subsequent EPA correspondence
granting reconsideration are in the docket for this rulemaking; see
Document ID No. EPA-HQ-OAR-2023-0282-0044.
\14\ 749 F.3d 1055 (D.C. Cir. 2014).
\15\ A copy of the August 26, 2014, letter is in the docket for
this rulemaking; see Document ID No. EPA-HQ-OAR-2023-0282-0045.
\16\ 90 FR 42323 (Sept. 2, 2025).
\17\ Although the issues identified in this paragraph (in
addition to one other issue related to alternative compliance
demonstration methods for periods of startup and shutdown) were also
raised for 40 CFR part 63, subparts JJJ and MMM; this action does
not respond to the reconsideration of these NESHAP, as the EPA is
not reviewing those subparts in this action.
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D. Where can I get a copy of this document and other related
information?
In addition to the docket, an electronic copy of this final action
will be available on the internet. Following signature by the EPA
Administrator, the EPA will post a copy of this final action at <a href="https://www.epa.gov/stationary-sources-air-pollution/polyether-polyols-production-national-emission-standards-hazardous">https://www.epa.gov/stationary-sources-air-pollution/polyether-polyols-production-national-emission-standards-hazardous</a>. Following publication
in the Federal Register, the EPA will post the Federal Register version
and key technical documents at this same website.
Additional information is available on the Risk and Technology
Review (RTR) website at <a href="https://www.epa.gov/stationary-sources-air-pollution/risk-and-technology-review-national-emissions-standards-hazardous">https://www.epa.gov/stationary-sources-air-pollution/risk-and-technology-review-national-emissions-standards-hazardous</a>. This information includes an overview of the RTR program and
links to project websites for the RTR source categories.
E. Judicial Review and Administrative Reconsideration
Under CAA section 307(b)(1), judicial review of this final action
is available only by filing a petition for review in the United States
Court of Appeals for the District of Columbia Circuit by May 18, 2026.
CAA section 307(b)(2) prohibits a party from challenging this final
rule separately in any civil or criminal proceedings brought by the EPA
for enforcement.
CAA section 307(d)(7)(B) further provides that only an objection to
a rule or procedure that was raised with reasonable specificity during
the period for public comment (including any public hearing) may be
raised during judicial review. This section also provides a mechanism
for the EPA to reconsider the rule if the person raising an objection
can demonstrate to the Administrator that it was impracticable to raise
such objection within the period for public comment or if the grounds
for such objection arose after the period for public comment (but
within the time specified for judicial review) and if such objection is
of central relevance to the outcome of the rule. Any person seeking to
make such a demonstration should submit a Petition for Reconsideration
to the Office of the Administrator, U.S. EPA, Room 3000, WJC South
Building, 1200 Pennsylvania Ave. NW, Washington, DC 20460, with a copy
to both the person(s) listed in the FOR FURTHER INFORMATION CONTACT
section of this preamble and the Associate General Counsel for the Air
and Radiation Law Office, Office of General Counsel (Mail Code 2344A),
U.S. EPA, 1200 Pennsylvania Ave. NW, Washington, DC 20460.
F. Severability
This final rule contains several discrete components, which the EPA
views as severable as a practical matter--i.e., they are functionally
independent and will operate in practice independently of the other
components. These discrete components are detailed in sections III.A
through III.D of this preamble and the technical memoranda available in
the docket. For example, the final requirements for equipment in
organic HAP service, equipment in EtO service, flare operation and
monitoring, transfer operations, and performance testing generally
function independently of one another and would not be impacted if a
reviewing court were to vacate one or more of the other final
provisions. In addition, as this final rule revises an existing NESHAP,
the EPA notes that if a reviewing court were to vacate one or more of
the standards finalized here, the affected standards will revert to
those present in the 2014 RTR final rule.
II. Background
A. What is the PEPO Production source category, and how does the NESHAP
regulate HAP emissions from the source category?
The PEPO Production source category is the subject of this final
action. The EPA promulgated the PEPO NESHAP on June 1, 1999, and
codified the NESHAP at 40 CFR part 63, subpart PPP.\18\ As promulgated
in 1999 and further amended on July 1, 2004,\19\ and March 27,
2014,\20\ the PEPO NESHAP regulates HAP emissions from polyether polyol
manufacturing process units (PMPUs) \21\ that produce PEPO \22\ as
their primary product. A PMPU consists of purification systems,
reactors and their associated product separators and recovery devices,
distillation units and their associated distillate receivers and
recovery devices, other associated unit operations, storage vessels,
surge control vessels, bottoms receivers, product transfer racks,
connected ducts and piping, and combustion, recovery, or recapture
devices or systems. A PMPU also includes pumps, compressors, agitators,
PRDs, sampling connection systems, open-ended valves or lines, valves,
connectors, and instrumentation systems.
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\18\ 64 FR 29420 (June 1, 1999).
\19\ 69 FR 39862 (July 1, 2004).
\20\ 59 FR 17340 (Mar. 27, 2014).
\21\ A PMPU also includes flexible operation process units when
an owner or operator cannot determine that a PEPO is not the primary
product and a PEPO is produced or anticipated to be produced during
time spans described in 40 CFR 63.1420(e)(2).
\22\ PEPO are compounds formed through the polymerization of EtO
or propylene oxide or other cyclic ethers with compounds having one
or more reactive hydrogens (i.e., a hydrogen atom bonded to
nitrogen, oxygen, phosphorus, sulfur, etc.) to form polyethers
(i.e., compounds with two or more ether bonds). This definition of
PEPO excludes cellulose ethers (such as methyl cellulose,
carboxymethyl cellulose, hydroxyethyl cellulose, hydroxyethyl
cellulose, and hydroxypropyl methyl cellulose) and materials
regulated under the HON, such as glycols and glycol ethers.
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Manufacturers use PEPO to make a variety of other products
including lubricants, adhesives, sealants, cosmetics, pharmaceuticals,
soaps, and feedstock for polyurethanes production. Urethane grade PEPO
(i.e., those that are free of water) serve as raw material in the
production of polyurethanes, including slabstock and molded flexible
foams, rigid foams, and other polyurethanes, including microcellular
products, surface coatings, elastomers, fibers, adhesives, and
sealants.
Facilities produce PEPO by polymerizing either epoxides (i.e., a
three-membered cyclic ether, such as EtO or propylene oxide) or
tetrahydrofuran (THF). Facilities usually conduct the former process as
a batch process and the latter as a continuous process. EtO and
propylene oxide are both HAPs, but THF is not. In the original NESHAP,
the EPA created two subcategories of PEPO based on the use of either
epoxides or THF in polymerization.
The HAP emission sources at PEPO facilities include process vents,
storage vessels, equipment leaks, heat exchange systems, and
wastewater. In the production of PEPO, facilities use HAP primarily as
reactants or extraction solvents. HAP emitted from PEPO facilities
include EtO, propylene oxide, toluene, methanol, and glycol ethers. The
MACT standards for PEPO production include emission limits for process
vents; a combination of equipment standards and work practices for
storage vessels, wastewater, and
[[Page 13120]]
equipment leaks; and work practice standards for heat exchange systems.
As of December 1, 2025, the EPA identified 23 PEPO facilities in
operation that are subject to the PEPO NESHAP. The list of facilities
in the United States that are part of the PEPO Production source
category with processes subject to the PEPO NESHAP is in the document
titled List of Facilities Subject to the PEPO NESHAP, for Final Rule,
which is in the docket for this action.\23\
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\23\ Docket ID No. EPA-HQ-OAR-2023-0282.
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B. What changes did we propose for the PEPO Production source category
in our December 27, 2024, proposal?
On September 18, 2023, the EPA received a complaint alleging that
the Agency failed to undertake non-discretionary duties to conduct a
technology review of the PEPO NESHAP at least every eight years, and on
December 7, 2023, the plaintiffs amended the complaint to additionally
allege that the Agency unreasonably delayed taking final agency action
on reconsideration of the 2014 rule. As a result, on November 22, 2024,
the EPA entered into a consent decree to take action on the
reconsideration petition and the technology review of the PEPO NESHAP
by December 10, 2025, later amended to March 13, 2026. The EPA's
December 27, 2024, proposal addressed the Agency's statutory and
consent decree obligation to conduct another technology review pursuant
to CAA section 112(d)(6). However, the EPA also took the opportunity to
conduct a second, ``discretionary'' residual risk review and proposed
several standards based on the proposed results of that second review.
This section explains what the EPA proposed with respect to the second,
``discretionary'' residual risk review, the mandatory eight-year
technology review, and additional issues covered in the proposed rule.
1. Proposed Actions Related to CAA Section 112(f) Risk Assessment
The EPA proposed a second, ``discretionary'' residual risk review
for the PEPO Production source category focused on emissions of EtO
from PEPO sources. The EPA proposed control options for EtO under CAA
section 112(f) to reduce risk from the PEPO Production source category
as construed in the Agency's proposed findings. The EPA proposed under
CAA section 112(f) to require additional control of EtO emissions from:
(1) process vents, (2) storage vessels, (3) equipment leaks, (4) heat
exchange systems, and (5) wastewater ``in ethylene oxide service.''
\24\
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\24\ See 88 FR 25080 (Apr. 25, 2023) for the EPA's proposed
definition of ``in ethylene oxide service.''
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<bullet> For process vents and storage vessels in EtO service, the
EPA proposed that owners and operators reduce emissions of EtO by
either: (1) venting emissions through a closed vent system to a non-
flare control device that reduces EtO by greater than or equal to 99.9
percent by weight or to a concentration less than 1 parts per million
by volume (ppmv) for each process vent and storage vessel, or (2)
venting emissions through a closed vent system to a flare meeting new
proposed operating and monitoring requirements for flares. For process
vents, the EPA also proposed an annual limit of 5 pounds per year (lb/
yr) or less for all combined process vents as an alternative to the
percent control and concentration options.
<bullet> For equipment leaks in EtO service, the EPA proposed the
following combined requirements: monitoring of connectors in gas/vapor
and light liquid service at a leak definition of 100 ppmv on a monthly
basis with no reduction in monitoring frequency and no delay of repair;
monthly monitoring of light liquid pumps at a leak definition of 500
ppmv; and monthly monitoring of gas/vapor and light liquid valves at a
leak definition of 100 ppmv with no reduction in monitoring frequency
and no delay of repair.\25\
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\25\ Leak definition refers to the concentration at or above
which the equipment is considered leaking, and the owner or operator
must repair the leaking equipment.
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<bullet> For heat exchange systems in EtO service, the EPA proposed
to require owners or operators to conduct more frequent leak monitoring
(weekly instead of quarterly) and to repair leaks within 15 days from
the sampling date (in lieu of the current 45-day repair requirement
after receiving results of monitoring indicating a leak), and to not
allow owners or operators to delay repairs.
<bullet> For wastewater in EtO service, the EPA proposed to revise
the Group 1 wastewater stream threshold for sources to include
wastewater streams in EtO service, and to prohibit owners and operators
from injecting wastewater in EtO service into or disposing of water
through any heat exchange system in a PMPU.
The EPA proposed that these requirements would reduce risk to an
acceptable level for the PEPO Production source category and provide an
ample margin of safety under the proposed approach to utilize CAA
section 112(f)(2). We also proposed that no additional requirements
were needed to prevent an adverse environmental effect.
2. Proposed Actions Related to CAA Section 112(d)(6) Technology Review
Pursuant to the CAA section 112(d)(6) technology review for the
PEPO NESHAP, the EPA proposed that no revisions to the current
standards beyond the fenceline monitoring work practice standard
discussed later in this preamble are necessary for wastewater streams.
However, the Agency proposed additional changes under CAA section
112(d)(6) for heat exchange systems, storage vessels, process vents,
and equipment leaks. The EPA also proposed a fenceline monitoring work
practice standard under CAA section 112(d)(6).
<bullet> For heat exchange systems at existing and new affected
sources, the EPA proposed requirements that owners or operators conduct
quarterly monitoring (after an initial six months of monthly monitoring
if not already completed) using the Modified El Paso Method and a leak
definition of 6.2 ppmv of total strippable hydrocarbon concentration
(as methane) in the stripping gas.\26\
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\26\ The Modified El Paso Method uses a dynamic or flow-through
system for air stripping a sample of the water and analyzing the
resultant off-gases for volatile organic compounds (VOC) using a
common flame ionization detector analyzer.
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<bullet> For storage vessels at existing and new affected sources,
the EPA proposed to revise applicability thresholds to require existing
storage vessels between 38 cubic meters (m\3\) (10,000 gal) and 151
m\3\ (40,000 gal) with a vapor pressure >=6.9 kilopascals (kPa) to add
controls, and to require upgraded deck fittings and controls for
guidepoles for all storage vessels equipped with an internal floating
roof (IFR).
<bullet> For continuous process vents at existing and new affected
sources associated with nonepoxide organic HAP (from making or
modifying product) and process vents associated with existing and new
affected sources that produce PEPO using THF, the EPA proposed to: (1)
remove the total resource effectiveness (TRE) concept in its entirety;
(2) remove 50 ppmv and 0.005 standard cubic meters per minute (scmm)
Group 1 process vent thresholds associated with a PMPU using THF; and
(3) redefine a Group 1 process vent (require control) as any process
vent that emits >=1.0 pounds per hour (lb/hr) of total organic HAP.
<bullet> For batch process vents at existing and new affected
sources that are associated with the use of a nonepoxide organic HAP to
make or modify the
[[Page 13121]]
product, the EPA proposed to change the PEPO NESHAP control threshold
from 26,014 lb/yr to 10,000 lb/yr and remove the associated flow rate
applicability thresholds.
<bullet> For equipment leaks at existing and new affected sources,
the EPA proposed to revise the leak definition from 500 ppmv to 100
ppmv for valves that are in either gas/vapor service or light liquid
service.
<bullet> For managing fugitive emissions, the EPA proposed a
fenceline monitoring work practice standard requiring owners and
operators to monitor EtO if their site uses, produces, stores, or emits
EtO, and conduct a root cause analysis and corrective action upon
exceeding an annual average EtO concentration action level of 0.2
micrograms per cubic meter ([micro]g/m\3\).
3. Proposed Actions Related to CAA Section 112(d)(2) and (3) and 112(h)
The EPA proposed other requirements for the PEPO NESHAP based on
analyses performed pursuant to CAA section 112(d)(2) and (3) and 112(h)
and to ensure that CAA section 112 standards apply continuously, as
required by Sierra Club v. EPA.\27\ These proposed requirements
included:
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\27\ 551 F.3d 1019 (D.C. Cir. 2008).
---------------------------------------------------------------------------
<bullet> new monitoring and operational requirements for flares;
<bullet> regulatory provisions for vent control bypasses for closed
vent systems containing bypass lines;
<bullet> work practice standards for startup and shutdown periods
for maintenance vents and planned routine maintenance of storage
vessels;
<bullet> new monitoring requirements for pressure vessels;
<bullet> new emission standards for surge control vessels and
bottoms receivers;
<bullet> new emission standards for transfer operations;
<bullet> the addition of butylene oxide to the list of HAP
presented in table 4 to 40 CFR 63, subpart PPP; and
<bullet> removal of exemption at 40 CFR 63.1420(d)(3) for certain
processes currently excluded from the affected source as defined in 40
CFR 63.1420(a).
4. Other Proposed Actions
In addition to the actions described in sections II.B.1 through
II.B.3 of this preamble, the EPA also proposed:
<bullet> to retain the existing PRD requirements in the PEPO NESHAP
(in response to the Agency's reconsideration of issue (2) in the
petition for reconsideration described in section I.C.2 of this
preamble);
<bullet> to change the recordkeeping and reporting requirements to
require the use of the EPA's Central Data Exchange (CDX) using the
Compliance and Emissions Data Reporting Interface (CEDRI) for
performance test reports, flare management plans, and periodic reports;
<bullet> to require subsequent performance testing once every five
years to demonstrate compliance with emission limits for certain
process vents (if you route emissions to a control device other than a
flare);
<bullet> to eliminate the option in 40 CFR 63.1427(a)(2)(ii) that
exempts owners or operators using extended cookout (ECO) as a control
technique from the requirement to directly measure the concentration of
unreacted epoxide of some products when determining the batch cycle
percent epoxide emission reduction; \28\
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\28\ ECO refers to extending the duration of the PEPO
polymerization reaction to reduce the quantity of unreacted epoxides
at the end of the reaction, thereby reducing epoxide emissions that
would occur after opening the reactor. The PEPO NESHAP allows owners
and operators to use ECO as a control technique to comply with the
epoxide standard for process vents.
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<bullet> to revise the phrasing in 40 CFR 63.1423(a) to refer to 40
CFR part 63, subpart F, where a definition in the PEPO NESHAP currently
points to either 40 CFR part 63, subpart G or H;
<bullet> to add monitoring requirements for adsorbers that cannot
be regenerated and regenerative adsorbers that are regenerated offsite;
<bullet> to find that the inclusion of 1-bromopropane (1-BP) as an
organic HAP will not have any effect on the MACT standards; and
<bullet> to make additional changes that address technical and
editorial corrections for the PEPO NESHAP.
III. What is included in this final rule?
Upon further consideration of the issues and public comments
received, the EPA is finalizing EtO-specific standards (similar to
those proposed under CAA section 112(f)(2)) under CAA section 112(d)(6)
and is not finalizing the proposed second residual risk review for the
PEPO Production source category (see section III.A of this preamble).
The EPA is also finalizing the Agency's determinations pursuant to the
technology review provisions of CAA section 112(d) for the PEPO
Production source category and amending the PEPO NESHAP in several
respects based on those determinations.\29\ In this action, the EPA is
also finalizing other changes to the PEPO NESHAP, including amendments
pursuant to CAA section 112(d)(2) and (3) and 112(h), described in
sections III.C and III.D of this preamble. This action also reflects
several changes to the December 27, 2024, proposal in consideration of
comments received during the public comment period, as described in
section IV of this preamble.
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\29\ See section III.B of this preamble for a summary of
requirements the EPA is finalizing for the PEPO NESHAP under the
technology review.
---------------------------------------------------------------------------
A. What are the final rule amendments based on the second residual risk
review for the PEPO Production source category?
As explained later in this preamble, after further consideration of
the issues and public comments received, the EPA is not finalizing the
proposed second, ``discretionary'' residual risk review for the PEPO
Production source category.\30\ Consequently, the EPA is not finalizing
any standards under CAA section 112(f)(2), although the Agency is
finalizing EtO-specific standards under CAA section 112(d)(6), which
requires periodic technology reviews and authorizes the Agency to
revise the NESHAP ``as necessary.'' The EtO-specific standards being
finalized under CAA section 112(d)(6) are discussed in the following
sections.
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\30\ See section IV.A of this preamble for additional details.
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B. What are the final rule amendments based on the technology review
for the PEPO Production source category?
For heat exchange systems, the EPA determined that developments in
practices, processes, and control technologies have occurred that
warrant revisions to the MACT standards for heat exchange systems in
the PEPO Production source category. Therefore, pursuant to CAA section
112(d)(6) and consistent with the proposed rule, the EPA is revising
the MACT standards for the heat exchange systems.\31\ These revisions
will now require that owners and operators conduct quarterly monitoring
for existing and new heat exchange systems (after an initial six months
of monthly monitoring if not already completed) using the Modified El
Paso Method and repair leaks of total strippable hydrocarbon
concentration (as methane) in the stripping gas of 6.2 ppmv or greater.
---------------------------------------------------------------------------
\31\ See 40 CFR 63.1435(a), which references the Hazardous
Organic NESHAP (HON) (i.e., 40 CFR 63.104(g) through (j) and (l))
and accounts for differences between the HON and the PEPO NESHAP.
---------------------------------------------------------------------------
The EPA is also finalizing, as proposed, a provision allowing
owners and operators to use the current leak monitoring requirements
for heat exchange systems at 40 CFR 63.104(b) in lieu of using the
Modified El Paso Method, provided that 99 percent by weight or more of
the organic
[[Page 13122]]
compounds that could leak into the heat exchange system are both water
soluble and have a Henry's Law Constant less than 5.0E-6 atmospheres-
cubic meters/mol at 25 degrees Celsius. The EPA is also finalizing
requirements under CAA section 112(d)(6) for heat exchange systems that
emit EtO. For these heat exchange systems, the EPA is finalizing the
term ``in ethylene oxide service'' at 40 CFR 63.1423(b) to mean any
heat exchange system in a process that cools process fluids (liquid or
gas) that are 1.0 percent or greater by weight of EtO. In addition, the
EPA is finalizing a requirement to conduct monthly monitoring for leaks
for heat exchange systems in EtO service using the Modified El Paso
Method.\32\ If an owner or operator finds a leak, the EPA is requiring
repair of the leak to reduce the concentration or mass emissions rate
below the applicable leak action level as soon as practicable but no
later than 45 days after the owner or operator receives results of
monitoring tests indicating a leak. The EPA is also not allowing delay
of repair of leaks for more than 30 days if subsequent monitoring
determines the presence of a total strippable hydrocarbon concentration
(as methane) in the stripping gas of 62 ppmv or higher.\33\ Sections
IV.B.2 through IV.B.4 of this preamble provide a more in-depth analysis
of the decision to finalize additional requirements for heat exchange
systems operating in EtO service, pursuant to CAA section 112(d)(6).
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\32\ See 40 CFR 63.1435(i), which references the HON and
accounts for differences between the HON and the PEPO NESHAP.
\33\ See 40 CFR 63.1435(i).
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For storage vessels, the EPA determined that developments in
practices, processes, and control technologies have occurred that
warrant revisions to the MACT standards for storage vessels in the PEPO
Production source category. Therefore, pursuant to CAA section
112(d)(6) and consistent with the proposed rule, the EPA is revising
the MACT standards to change the Group 1 storage capacity criterion for
storage vessels at new and existing sources, from the former range of
75 m\3\ (inclusive) to 151 m\3\ to the new range of 38 m\3\ (inclusive)
to 151 m\3\,\34\ and to require upgraded deck fittings and controls for
guidepoles for all storage vessels equipped with an IFR, as already
required in 40 CFR part 63, subpart WW.\35\ The EPA is also finalizing
requirements under CAA section 112(d)(6) for storage vessels that emit
EtO. For these storage vessels, the EPA is finalizing, pursuant to CAA
section 112(d)(6), the term ``in ethylene oxide service'' at 40 CFR
63.1423(b) to mean that the concentration of EtO in the stored liquid
is greater than or equal to 1.0 percent by weight. The EPA is
finalizing at 40 CFR 63.1432(s) a requirement--by reference to the
Hazardous Organic NESHAP (HON) (i.e., 40 CFR 63.119(a)(5)) and
accounting for differences between the HON and the PEPO NESHAP--that
PEPO storage vessels in EtO service reduce emissions of EtO by either:
(1) venting emissions through a closed vent system to a non-flare
control device that reduces EtO by at least 99.9 percent by weight or
to a concentration less than 1 ppmv for each storage tank vent; or (2)
venting emissions through a closed vent system to a flare meeting the
flare operating requirements that the EPA is finalizing, as proposed,
and discussed in section IV.C of this preamble.\36\ Sections IV.B.2
through IV.B.4 later in this preamble provide a more in-depth analysis
of decision to finalize additional requirements for storage vessels in
EtO service pursuant to CAA section 112(d)(6).
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\34\ See table 3 to 40 CFR part 63, subpart PPP.
\35\ See 40 CFR 63.1432, which refers to the HON including 40
CFR 63.119(b)(5)(ix), (x), (xi), and (xii).
\36\ See 40 CFR 63.1436.
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For continuous process vent requirements, the final rule retains
the use of the TRE index value concept and the current definition of a
``Group 1 continuous process vent.'' This definition refers to a
process vent from a continuous unit operation that is associated with
the use of a nonepoxide organic HAP to make or modify the product and
that has: (1) a flow rate greater than or equal to 0.005 scmm, (2) a
total organic HAP concentration greater than or equal to 50 ppmv, and
(3) a TRE index value less than or equal to 1.0. However, for batch
process vents, the EPA determined that there are developments in
practices, processes, and control technologies that warrant revisions
to the MACT standards for process vents in the PEPO Production source
category. Therefore, pursuant to CAA section 112(d)(6), the EPA is
revising the MACT standards, consistent with the proposed rule, to
change the Group 1 combination of batch process vents threshold (for
batch process vents that are associated with the use of a nonepoxide
organic HAP to make or modify the product) from 26,014 lb/yr to 10,000
lb/yr and to remove the associated flow rate applicability threshold
specified in the PEPO NESHAP at 40 CFR 63.1423(b). The EPA is also
finalizing requirements under CAA section 112(d)(6) for process vents
that emit EtO. For these process vents, the EPA is finalizing the term
``in ethylene oxide service'' at 40 CFR 63.1423(b) to mean each process
vent in a process that, when uncontrolled, contains a concentration of
greater than or equal to 1 ppmv undiluted EtO, and when combined, the
sum of all these process vents within the process would emit
uncontrolled EtO emissions greater than or equal to 100 lb/yr (45.4
kilograms per year, kg/yr). The EPA is finalizing at 40 CFR 63.1425(g)
a requirement that PEPO process vents in EtO service reduce emissions
of EtO by either: (1) venting emissions through a closed vent system to
a non-flare control device that reduces EtO by at least 99.9 percent by
weight, to a concentration less than 1 ppmv for each process vent, or
to less than 100 lb/yr for all combined process vents within the
process; or (2) routing emissions through a closed vent system to a
flare meeting the flare operating requirements that the EPA is
finalizing, as proposed and as discussed in section IV.C of this
preamble.\37\ Sections IV.B.2 through IV.B.4 of this preamble provide a
more in-depth analysis of the decision to finalize requirements for
process vents in EtO service pursuant to CAA section 112(d)(6).
---------------------------------------------------------------------------
\37\ See 40 CFR 63.1436.
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The EPA's proposed technology review for wastewater streams
concluded that no developments in practices, processes, or control
technologies warrant revisions to the MACT standards. However, this was
because the Agency proposed stringent EtO-specific standards under CAA
section 112(f)(2) and thus proposed to conclude that additional
standards were not ``necessary'' under CAA section 112(d)(6). In
response to comments recommending that the EPA evaluate the proposed
EtO-specific standard for wastewater under CAA section 112(d)(6), the
EPA is finalizing an EtO-specific standard for wastewater as
``necessary'' under CAA section 112(d)(6) rather than under CAA section
112(f)(2) as initially proposed.
Based on this evaluation, the EPA is finalizing additional
requirements under CAA section 112(d)(6) for wastewater that contains,
and thus emits, EtO. For these wastewater streams, the EPA is
finalizing the term ``in ethylene oxide service'' at 40 CFR 63.1423(b)
to mean any wastewater stream that contains a total annual average
concentration of EtO greater than or equal to 10 parts per million by
weight (ppmw) at any flow rate. The EPA is finalizing at 40 CFR
63.1433(s)(23) a requirement--by reference to the HON and accounting
for differences between the HON and the
[[Page 13123]]
PEPO NESHAP--that owners and operators reduce the concentration of EtO
of each wastewater stream, by removal or destruction, to a level less
than 1 ppmw, or comply with the Group 1 wastewater stream control
requirements outlined in 40 CFR 63.138(d) or (e). Additionally, the EPA
is finalizing an exemption to this requirement for wastewater streams
in EtO service that cumulatively contain less than 1 megagram
(approximately 1.1 tons) of EtO per year. Sections IV.B.2 through
IV.B.4 of this preamble provide a more in-depth analysis of the
decision to finalize requirements for wastewater in EtO service
pursuant to CAA section 112(d)(6).
For equipment leaks, the EPA determined there are developments in
practices, processes, and control technologies that warrant revisions
to the MACT standards for equipment leaks in the PEPO Production source
category. Therefore, pursuant to CAA section 112(d)(6) and consistent
with the proposed rule, the EPA is revising the MACT standards to use a
leak definition of 100 ppmv for valves that are in either gas/vapor
service or light liquid service.\38\ The EPA is also finalizing
requirements under CAA section 112(d)(6) for equipment that emits EtO
via equipment leaks. For this equipment, the EPA is finalizing the term
``in ethylene oxide service'' at 40 CFR 63.1423(b) to mean any
equipment that contains or contacts a fluid (liquid or gas) that is at
least 1.0 percent by weight EtO. The EPA is finalizing at 40 CFR
63.1434(a)(3) requirements--by reference to the HON and accounting for
differences between the HON and the PEPO NESHAP--for quarterly
monitoring at a leak definition of 100 ppmv for connectors in gas and
vapor service or in light liquid service in EtO service, monthly
monitoring at a leak definition of 100 ppmv for valves in gas and vapor
service or in light liquid service in EtO service, and monthly
monitoring at a leak definition of 500 ppmv for pumps in light liquid
service in EtO service. Additionally, the EPA is finalizing
requirements for owners or operators to repair a detected leak as soon
as practicable but no later than 15 days after collecting the sample,
allowing delayed repair for a small amount of equipment in EtO
service.\39\ Sections IV.B.2 through IV.B.4 later in this preamble
provide a more in-depth analysis of the decision to finalize additional
requirements for equipment in EtO service pursuant to CAA section
112(d)(6).
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\38\ See 40 CFR 63.1434(a)(6).
\39\ See 40 CFR 63.1434(a)(3).
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Section III.E of this preamble provides a detailed discussion of
the effective and compliance dates for the requirements the EPA is
finalizing in this action for the PEPO NESHAP. Section IV.B.3 of this
preamble provides a summary of key comments the EPA received on the
proposed CAA section 112(d)(6) provisions and the Agency's responses.
Section IV.B.3 also explains the basis for the EPA's decision to
finalize specific requirements for EtO emissions under CAA section
112(d)(6).
C. What are the final rule amendments we are taking pursuant to CAA
section 112(d)(2) and (3) and 112(h) for the PEPO Production source
category?
Consistent with Sierra Club v. EPA \40\ and the proposed rule,\41\
the EPA is revising monitoring and operational requirements for flares
to ensure that PEPO flares meet MACT standards at all times when
controlling HAP emissions.\42\ In addition, the EPA is finalizing
provisions and clarifications for bypass lines on closed vent
systems.\43\ The EPA is also finalizing work practice standards for
certain activities where alternatives are appropriate, including:
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\40\ 551 F.3d 1019 (D.C. Cir. 2008).
\41\ 89 FR 105986 (Dec. 27, 2024).
\42\ See 40 CFR 63.1436.
\43\ See 40 CFR 63.1425(f), by references to 40 CFR 63.114(d)(2)
and (3), 63.118(a)(5) and (f)(7), 40 CFR 63.1429(c)(3), and 40 CFR
63.1430(d)(6) and (h)(7).
---------------------------------------------------------------------------
<bullet> maintenance vents and equipment openings (excluding
storage vessel degassing); \44\
---------------------------------------------------------------------------
\44\ See 40 CFR 63.1425(f) by reference to 40 CFR 63.113(k) for
process vents at PMPUs that produce PEPO products using THF, and 40
CFR 63.1425(h) for all other regulated PEPO process vents.
---------------------------------------------------------------------------
<bullet> storage vessel degassing; \45\ and
---------------------------------------------------------------------------
\45\ See 40 CFR 63.1432(a), by reference to 40 CFR 63.119(a)(6).
---------------------------------------------------------------------------
<bullet> planned routine maintenance for storage vessels.\46\
---------------------------------------------------------------------------
\46\ See 40 CFR 63.1432(a), by reference to 40 CFR 63.119(e)(7).
---------------------------------------------------------------------------
The EPA is also finalizing the proposed requirements for several
other PEPO emission sources, including:
<bullet> pressure vessels; \47\
---------------------------------------------------------------------------
\47\ See 40 CFR 63.1432(a), by reference to 40 CFR 63.119(a)(7).
---------------------------------------------------------------------------
<bullet> surge control and bottoms receivers; \48\
---------------------------------------------------------------------------
\48\ See 40 CFR 63.1434(a)(7).
---------------------------------------------------------------------------
<bullet> transfer racks; \49\
---------------------------------------------------------------------------
\49\ See 40 CFR 63.1434(i), which references the HON at 40 CFR
63.126 through 63.130 and accounts for difference between the HON
and the PEPO NESHAP.
---------------------------------------------------------------------------
<bullet> process units using butylene oxide; \50\ and
---------------------------------------------------------------------------
\50\ See 40 CFR 63.1423(b) for the definition of ``epoxide'' and
the list of HAP presented in table 4 to the PEPO NESHAP.
---------------------------------------------------------------------------
<bullet> affected source reactions or processing that occur after
completion of epoxide polymerization and all catalyst removal steps, if
any (which may include, but are not limited to, solvent removal,
purification, drying, and solids handling operations).\51\
---------------------------------------------------------------------------
\51\ See 40 CFR 63.1420(d)(3).
---------------------------------------------------------------------------
The EPA is finalizing the requirements with a few changes from the
proposed rule, after considering comments the EPA received during the
public comment period. In response to comments received on the proposed
provisions for flares, the EPA is allowing the use of pressure-assisted
multi-point flares as a control option, provided they meet certain
operational and monitoring requirements. In response to comments
received on the proposed provisions for affected source reactions or
processing that occur after completion of epoxide polymerization and
all catalyst removal steps, the EPA is including overlap provisions for
owners and operators currently complying with the Miscellaneous Organic
Chemical Manufacturing NESHAP (MON).
The comments and the EPA's specific responses to the items
discussed earlier in this preamble are in the document titled Summary
of Public Comments and Responses for National Emission Standards for
Hazardous Air Pollutants for Polyether Polyols Production Industry,
which is in the docket for this rulemaking, and in section IV.C.3 of
this preamble.
D. What other changes have we made to the NESHAP?
This rule also finalizes, as proposed, revisions to several other
PEPO NESHAP requirements. This section describes these revisions, as
well as other provisions that have changed since proposal.
To increase the ease and efficiency of data submittal and data
accessibility, the EPA is finalizing, as proposed, a requirement that
owners or operators submit electronic copies of continuous monitoring
system performance evaluations,\52\ flare management plans,
Notification of Compliance Status reports, and periodic reports through
the EPA's CDX using the CEDRI.\53\ The PEPO NESHAP already requires
electronic submittal of performance test results collected using test
methods that are compatible with the EPA-provided
[[Page 13124]]
software. In addition to the new electronic reporting requirements, the
EPA is making minor updates to the electronic reporting language for
performance tests that do not change the requirements but reflect the
EPA's current electronic reporting process (e.g., noting the required
software and the system to which the reports are submitted). A
description of the electronic data submission process is in the
memorandum Electronic Reporting Requirements for New Source Performance
Standards (NSPS) and National Emission Standards for Hazardous Air
Pollutants (NESHAP) Rules.\54\ The final rule requires that owners and
operators submit performance test results in the format generated
through the use of the EPA's Electronic Reporting Tool (ERT) or an
electronic file consistent with the XML schema on the ERT website.\55\
Similarly, owners and operators must submit performance evaluation
results of CEMS in the format generated through the use of the ERT or
an electronic file consistent with the XML schema on the ERT website.
For both performance test results and CEMS performance evaluation
results, all the information required by 40 CFR 63.7(g)(2) in PDF
format must accompany electronic files consistent with the XML schema
on the ERT website.
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\52\ If a continuous emission monitoring system (CEMS) is used
to continuously monitor the EtO concentration at the exit of an air
pollution control device (APCD) as allowed at 40 CFR 63.1426(g) and
40 63.1432(s), by reference to 40 CFR 63.124.
\53\ See 40 CFR 63.1436(b); and 40 CFR 63.1439(e)(5), (6), and
(9).
\54\ Document ID No. EPA-HQ-OAR-2023-0282-0016.
\55\ <a href="https://www.epa.gov/electronic-reporting-air-emissions/electronic-reporting-tool-ert">https://www.epa.gov/electronic-reporting-air-emissions/electronic-reporting-tool-ert</a>.
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For periodic reports, the final rule requires that owners or
operators use the appropriate spreadsheet template to submit
information to CEDRI. The EPA has made minor clarifying edits to the
spreadsheet templates based on comments received during the public
comment period. The final version of the template for these reports
will be on the CEDRI website.\56\ The final rule requires that owners
or operators submit flare management plans as a PDF upload in CEDRI.
For a more detailed discussion of these final amendments, see section
III.E.2 of the proposal preamble, as well as sections IV.D and VI.C of
this preamble.
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\56\ <a href="https://www.epa.gov/electronic-reporting-air-emissions/cedri">https://www.epa.gov/electronic-reporting-air-emissions/cedri</a>.
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The EPA is also finalizing at 40 CFR 63.1437(a), as proposed,
performance testing once every five years to demonstrate compliance
with emission limits for certain process vents that route emissions to
a control device other than a flare. Specifically, the EPA is
finalizing the removal of the design evaluation option at 40 CFR
63.1426(b)(6) and (7) and (f) and requiring ongoing performance tests
for owners and operators using a combustion, recovery, or recapture
device to comply with: an epoxide or organic HAP percent reduction
efficiency requirement in 40 CFR 63.1425(b)(1)(i), (b)(2)(ii),
(c)(1)(ii), (c)(3)(ii), or (d)(2); an epoxide concentration limitation
in 40 CFR 63.1425(b)(1)(ii) or (b)(2)(iii); or an annual epoxide
emission limitation in 40 CFR 63.1425(b)(1)(iii) or (b)(2)(iv).
The EPA is also finalizing, as proposed, the elimination of the
option in 40 CFR 63.1427(a)(2)(ii) that exempts owners and operators
using ECO as a control technique from the requirement to directly
measure the concentration of unreacted epoxide for a representative
product of each product class when determining the batch cycle percent
epoxide emission reduction. However, based on comments received on the
proposed rulemaking, in the final rule the EPA is limiting the number
of product classes requiring direct measurement.\57\
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\57\ See 40 CFR 63.1427(a)(2)(iii).
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Also, the EPA is finalizing as proposed both the phrasing used in
40 CFR 63.1423(a) to refer to 40 CFR part 63, subpart F, in instances
where a definition in the PEPO NESHAP points to either 40 CFR part 63,
subpart G or H, and the clarifying revisions to 40 CFR 63.1423(b) to
reference the correct HON citation for ``continuous recorder,''
``maximum true vapor pressure,'' ``residual,'' and ``waste management
unit.'' Additionally, the EPA is finalizing the proposed definition of
``heat exchange system'' at 40 CFR 63.1423(b) to mean a device or
collection of devices used to transfer heat from process fluids to
water without intentional direct contact of the process fluid with the
water (i.e., non-contact heat exchanger) and to transport and/or cool
the water in a closed-loop recirculation system (cooling tower system)
or a once-through system (e.g., river or pond water). For closed-loop
recirculation systems, the heat exchange system consists of a cooling
tower, all PMPU heat exchangers that are in organic HAP service and
serviced by that cooling tower, and all water lines to and from these
process unit heat exchangers. For once-through systems, the heat
exchange system consists of all heat exchangers in an individual PMPU
that are in organic HAP service and all water lines to and from these
heat exchangers. Sample coolers or pump seal coolers are not considered
heat exchangers for the purpose of this definition and are not part of
the heat exchange system. Intentional direct contact with process
fluids results in the formation of a wastewater. The EPA is also
finalizing the proposed definition of ``in organic HAP service'' to
include a heat exchange system, to be consistent with the use of ``in
organic HAP service'' in the definition of ``heat exchange system.''
In addition, the EPA is finalizing requirements, as proposed, at 40
CFR 63.1429(a)(9) for owners or operators using adsorbers that cannot
be regenerated or using regenerative adsorbers that are regenerated
offsite to use dual (two or more) adsorbent beds in series and to
conduct monitoring of HAP or total organic compound (TOC) on the outlet
of the first adsorber bed in series using a sample port and a portable
analyzer or chromatographic analysis. Lastly, the EPA is finalizing all
the revisions that the Agency proposed for clarifying text and
correcting typographical errors, grammatical errors, and cross-
reference errors. The EPA discussed these editorial corrections and
clarifications in section IV.E.7 of the proposal preamble. The EPA is
also including several minor clarifying edits in the final rule based
on comments received during the public comment period.
The comments and the EPA's specific responses to the items
discussed in this section are in the document titled Summary of Public
Comments and Responses for National Emission Standards for Hazardous
Air Pollutants for Polyether Polyols Production Industry, which is in
the docket for this rulemaking, and section IV.D.3 of this preamble.
E. What are the effective and compliance dates of the standards?
For all the requirements the EPA is finalizing under CAA section
112(d)(2), (3), and (6) and 112(h), all existing affected sources and
all affected sources that were new sources under the previous PEPO
NESHAP (i.e., any source that commenced construction or reconstruction
after September 4, 1997, and on or before December 27, 2024) must
comply with all of the amendments no later than March 18, 2029, or upon
startup, whichever is later. For existing sources, CAA section 112(i)
provides that the compliance date for standards promulgated under
section 112(d) shall be as expeditious as practicable, but no later
than three years after the effective date of the standard.\58\ The EPA
agrees with commenters that owners and operators need at least three
[[Page 13125]]
years to implement the requirements the Agency is finalizing under CAA
section 112(d)(2), (3), and (6).\59\ For example, for process vents and
storage vessels in EtO service, if an affected source has uncontrolled
process vents or storage vessels that meet the definition of ``in
ethylene oxide service,'' owners or operators may need to install a new
control system, such as a thermal oxidizer with piping, ductwork, etc.
Owners or operators may require additional permits (e.g., New Source
Review and/or title V operating permit modifications) to install new
emission control equipment. Moreover, owners and operators need at
least three years to understand the final rule changes; revise site
guidance and compliance programs; ensure operations can meet the
standards during startup and shutdown; update operation, maintenance,
and monitoring plans; upgrade emission capture and control systems;
install new flare monitoring equipment; and install new process control
systems. As provided in CAA section 112(i) and 5 U.S.C. 801(3), all new
affected sources that commenced construction or reconstruction after
December 27, 2024, must comply with all requirements under CAA section
112(d)(2), (3), (6), and 112(h) by March 18, 2026, or upon startup,
whichever is later. The EPA provided additional rationale for these
compliance dates in the preamble to the proposed rule. The EPA is also
finalizing provisions, as proposed, that provide 60 days after the
publication date of the final rule (or upon startup, whichever is
later) for owners or operators of affected sources to comply with the
requirement to submit Notification of Compliance Status reports
electronically. The EPA is finalizing provisions that provide 60 days
after the publication date of the final rule for owners or operators of
affected sources to comply with the requirement to submit the results
of CEMS performance evaluations electronically. The EPA is also
finalizing provisions, as proposed, that provide three years after the
publication date of the final rule for owners or operators of affected
sources to comply with the requirements to submit periodic reports and
flare management plans electronically.
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\58\ Ass'n of Battery Recyclers, 716 F.3d at 672 (``Section
112(i)(3)'s three-year maximum compliance period applies generally
to any emission standard . . . promulgated under [section 112].'').
\59\ See section 7.0 of U.S. EPA, Summary of Public Comments and
Responses for National Emission Standards for Hazardous Air
Pollutants for Polyether Polyols Production Industry, in the docket
for this rulemaking.
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IV. What is the rationale for our final decisions and amendments for
the PEPO Production source category?
For each issue, this section provides a description of what the EPA
proposed and what the Agency is finalizing, the EPA's rationale for the
final decisions and amendments, and a summary of key comments and
responses. For all comments not discussed in this preamble, comment
summaries and the EPA's responses are in the document titled Summary of
Public Comments and Responses for National Emission Standards for
Hazardous Air Pollutants for Polyether Polyols Production Industry,
which is in the docket for this rulemaking.
A. Second Residual Risk Review for the PEPO Production Source Category
1. What did we propose pursuant to CAA section 112(f) for the PEPO
Production source category?
Although the EPA's statutory and consent decree obligations are
limited to the technology review requirement in CAA section 112(d)(6)
and reconsideration of specific 2014 RTR issues, the EPA proposed a
second, ``discretionary'' residual risk review for the PEPO Production
source category along with EtO-specific standards intended to reduce
risk based on the proposed findings. In this proposed review, the EPA
identified six facilities that emit EtO from process vents, storage
vessels, equipment leaks, or wastewater and have estimated individual
cancer risks greater than 100-in-1 million in nearby communities.
Additionally, in the proposed review, the EPA noted that an allowable
leak of EtO from a heat exchange system could contribute to individual
cancer risks greater than 100-in-1 million. Thus, the EPA proposed
control options under CAA section 112(f) to reduce EtO risk from the
PEPO Production source category.
In connection with the proposed second residual risk review, the
EPA proposed to require further control of EtO emissions from: (1)
process vents, (2) storage vessels, (3) equipment leaks, (4) heat
exchange systems, and (5) wastewater in EtO service. The proposed
definitions for being in EtO service included:
<bullet> For process vents, the EPA proposed ``in ethylene oxide
service'' to mean that when uncontrolled, each process vent contains a
concentration of greater than or equal to 1 ppmv undiluted EtO, and
when combined, the sum of all process vents within the process would
emit uncontrolled EtO emissions greater than or equal to 5 lb/yr.
<bullet> For storage vessels of any capacity and vapor pressure,
the EPA proposed ``in ethylene oxide service'' to mean that the
concentration of EtO within the tank liquid is greater than or equal to
0.1 percent by weight.
<bullet> For equipment leaks, the EPA proposed ``in ethylene oxide
service'' to mean any equipment that contains or contacts a fluid
(liquid or gas) that is at least 0.1 percent by weight of EtO.
<bullet> For heat exchange systems, the EPA proposed ``in ethylene
oxide service'' to mean any heat exchange system in a process that
cools process fluids (liquid or gas) that are 0.1 percent or greater by
weight of EtO.
<bullet> For wastewater, the EPA proposed ``in ethylene oxide
service'' to mean any wastewater stream that contains total annual
average concentration of EtO greater than or equal to 1 ppmw at any
flow rate.
For process vents and storage vessels in EtO service, the EPA
proposed that owners and operators reduce emissions of EtO by either:
(1) venting emissions through a closed vent system to a non-flare
control device that reduces EtO by greater than or equal to 99.9
percent by weight or to a concentration less than 1 ppmv for each
process vent and storage vessel, or (2) venting emissions through a
closed vent system to a flare that meets new proposed operating and
monitoring requirements for flares. For process vents, the EPA also
proposed an annual limit of 5 lb/yr or less for all combined process
vents as an alternative to the percent control and concentration
options. For equipment leaks in EtO service, the EPA proposed the
following combined requirements: monitoring of connectors in gas/vapor
and light liquid service at a leak definition of 100 ppmv on a monthly
basis with no reduction in monitoring frequency and no delay of repair;
monthly monitoring of light liquid pumps at a leak definition of 500
ppmv; and monthly monitoring of gas/vapor and light liquid valves at a
leak definition of 100 ppmv with no reduction in monitoring frequency
and no delay of repair. For heat exchange systems in EtO service, the
EPA proposed to require owners or operators to conduct more frequent
leak monitoring (weekly instead of quarterly) and to repair leaks
within 15 days from the sampling date (in lieu of the current 45-day
repair requirement after receiving results of monitoring indicating a
leak), and to not allow owners or operators to delay repairs. For
wastewater in EtO service, the EPA proposed to revise the Group 1
[[Page 13126]]
wastewater stream threshold for sources to include wastewater streams
in EtO service and to prohibit owners and operators from injecting
wastewater in EtO service into or disposing of water through any heat
exchange system in a PMPU.
In all cases, the EPA proposed that if information exists that
suggests EtO could be present in these processes, the emission source
is considered to be in EtO service unless the owner or operator
conducts the procedures specified in 40 CFR 63.109 to demonstrate that
the emission source does not meet the definition of being in EtO
service. The EPA proposed that examples of information that could
suggest EtO is present in a process stream include calculations based
on safety data sheets, material balances, process stoichiometry, or
previous test results, provided the results are still relevant to the
current operating conditions.
At the time of proposal and in the context of proposing to use CAA
section 112(f)(2) for this purpose, the EPA found that these proposed
requirements would reduce risk to an acceptable level and provide an
ample margin of safety to protect public health, and no additional
requirements were necessary to prevent an adverse environmental effect.
2. How did the risk review change for the PEPO Production source
category?
In this final rule, the EPA is not finalizing the proposed second
residual risk review for the PEPO Production source category and
instead is assessing and finalizing EtO-specific standards pursuant to
CAA section 112(d)(6). Consequently, the EPA is not finalizing the EtO-
specific standards outlined in section IV.A.1 in this action under CAA
section 112(f)(2).
3. What key comments did we receive on the risk review, and what are
our responses?
The EPA received numerous comments in support of and in opposition
to the Agency's proposed second residual risk review for the PEPO
Production source category. As the EPA has decided to not finalize any
components of the proposed second residual risk review for the PEPO
Production source category, the Agency is not including in this final
preamble any comment summaries or responses that are related to the
proposed second residual risk review authority, methodology or
findings. Instead, all these comments summaries are in the document
titled Summary of Public Comments and Responses for National Emission
Standards for Hazardous Air Pollutants for Polyether Polyols Production
Industry in the docket for this rulemaking. This section provides a
summary of and response to commenters' requests to consider evaluating
EtO-specific standards under CAA section 112(d)(6) instead of CAA
section 112(f)(2).
Comment: Regarding the decision to propose a second residual risk
review under CAA section 112(f)(2), some commenters supported the risk
review, but multiple commenters urged the EPA to consider regulatory
alternatives that provide the EPA with more flexibility. Commenters
noted that the EtO-specific standards are driven by technology
developments for emissions control devices and monitoring requirements
and are thus aligned with the CAA section 112(d)(6) technology review.
Commenters emphasized that the EPA should consider cost when setting
EtO-specific standards. Commenters also stated that the EPA should
allow facilities three years to comply with the new EtO-specific
standards.
Specifically, multiple commenters suggested that the EPA consider
evaluating EtO-specific standards (for process vents, storage vessels,
equipment leaks, heat exchange systems, and wastewater in EtO service)
under CAA section 112(d)(6) instead of under CAA section 112(f)(2). For
example, one commenter urged the EPA to ``withdraw the risk-based
portions of the proposal and repropose under the technology review
provisions'' and that ``more reasonable actions could achieve
meaningful reductions of E[t]O . . . while providing feasible
reductions and protecting the supply chain.'' \60\ The commenter also
requested that the EPA promulgate cost-effective standards for
equipment leaks under CAA section 112(d)(6) that will reduce emissions
of both organic HAP and EtO. Another commenter stated that the EPA
``should categorize and base the proposed ethylene oxide requirements
for Process Vents, Storage Tanks, and Wastewater under Section 112(d)
of the Clean Air Act instead of under the Section 112(f) residual risk
requirements.'' The commenter continued, ``In some cases, capital
projects will have to be implemented to meet the new emission
standards. The details of these requirements are largely developments
in technology that require installing or revising air pollution control
equipment for process vents or storage tanks and installing unit
operations to remove ethylene oxide from process wastewater streams.
These technologies will also require testing to confirm removal
efficiency or outlet concentrations along with the establishment of
operating parameters, and the continuous monitoring of operating
parameters. In some cases, the owner or operator will have to request
approval of the operating parameters to monitor from regulatory
agencies on a case-by-case basis. Taken together, these requirements
align more with Section 112(d) of the Clean Air Act.'' \61\
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\60\ Comment ID No. EPA-HQ-OAR-2023-0282-0103.
\61\ Comment ID No. EPA-HQ-OAR-2023-0282-0099.
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Response: The EPA agrees with commenters that it is more
appropriate to evaluate EtO-specific standards under CAA section
112(d)(6). CAA section 112(d)(6) provides that the EPA should consider
cost in deciding whether to revise the standards and allows a maximum
compliance timeline of three years (in contrast to the maximum of two
years allowed by CAA section 112(f)(2)). While the EPA may have
proposed EtO-specific standards under CAA section 112(f)(2), the
proposal demonstrated that there are developments in practices,
processes, and control technologies for reducing EtO emissions that
merit evaluation under CAA section 112(d)(6). As explained in section
IV.B.3 of this preamble, the EPA's evaluation under CAA section
112(d)(6) finds it appropriate to revise the PEPO NESHAP to include
additional standards for EtO. The EPA also agrees that facilities would
encounter significant difficulties complying with some of the proposed
requirements within two years as required by CAA section 112(f)(2).
4. What is the rationale for our final approach and final decisions for
the risk review?
In 2014, the EPA finalized a residual RTR for the PEPO NESHAP under
the provisions of CAA section 112(f)(2) and (d)(6).\62\ In 2024, the
EPA proposed a second residual risk review for the PEPO Production
source category and proposed to address residual risks associated with
EtO emissions from this source category, both pursuant to CAA section
112(f)(2). This was consistent with other recent approaches taken by
the EPA to address EtO emissions from chemical manufacturing facilities
such as the 2024 rulemaking amending the HON.\63\ The EPA is not
finalizing the residual risk review or the risk-based standards
proposed in 2024 pursuant to CAA section 112(f)(2). Several commenters
requested that the EPA
[[Page 13127]]
consider evaluating EtO-specific standards under CAA section 112(d)(6)
instead of under CAA section 112(f)(2). The EPA agrees with these
commenters that, in this circumstance, the technology review is the
more appropriate authority to use to target EtO emissions. The EPA also
notes that the consent decree requiring review of this NESHAP specifies
that a technology review under CAA section 112(d)(6) must be completed,
but it does not require a residual risk review under CAA section
112(f)(2). The EPA acknowledges that the evaluations conducted for the
proposed CAA section 112(f)(2) review demonstrated that there are
developments in practices, processes, or technology that can
meaningfully reduce EtO emissions for the PEPO Production source
category. Thus, in response to comments that the CAA section 112(d)(6)
framework is more appropriate to analyze these options, the EPA is
finalizing revisions that reflect those developments under the CAA
section 112(d)(6) authority, which requires the Agency to consider
factors such as cost, in lieu of finalizing the proposed CAA section
112(f)(2) review. See section IV.B.2 of this preamble for details
regarding the EPA's CAA section 112(d)(6) review for reducing EtO
emissions. The EPA notes that these finalized EtO-specific CAA section
112(d)(6) standards result in projected overall EtO emissions
reductions from the PEPO source category similar to those reductions
projected for the proposal. For all six facilities estimated in the
proposed risk assessment to have baseline source category cancer risks
greater than 100-in-1 million in nearby communities, the EPA estimates
that the final rule will result in significant emissions reductions
from baseline, which would lead to significant risk reductions compared
to baseline. Revisions to the baseline EtO emissions estimate of one of
the facilities have been incorporated into the EPA's final impact
analysis. More information about the estimated impacts of this final
action is in the document titled Updated Impact Calculations and
Technology Review for the PEPO Production Source Category--Final Rule,
which is in the docket for this rulemaking.
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\62\ 79 FR 17340 (Mar. 27, 2014).
\63\ See 89 FR 42932 (May 16, 2024), 2024 final rule amending
the HON.
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B. Technology Review for the PEPO Production Source Category
1. What did we propose pursuant to CAA section 112(d)(6) for the PEPO
Production source category?
Based on the EPA's technology review for the PEPO Production source
category, the Agency proposed changes under CAA section 112(d)(6) to
the PEPO NESHAP for heat exchange systems, storage vessels, process
vents, and equipment leaks in organic HAP service. In addition, the EPA
proposed no change under CAA section 112(d)(6) for wastewater streams
in organic HAP service. The EPA also proposed fenceline monitoring
requirements under CAA section 112(d)(6). This section provides a
summary of the Agency's findings, as proposed in 2024.
a. Heat Exchange Systems
In the EPA's technology review for the PEPO Production source
category, the Agency identified one development in practices and
processes for PEPO heat exchange systems in organic HAP service--the
use of the Modified El Paso Method for monitoring for leaks from heat
exchange systems.\64\ The EPA determined that this method is more
effective in identifying leaks and measures a larger number of
compounds than the previously required methods in the PEPO NESHAP.
After evaluating state and Federal regulations requiring the Modified
El Paso Method and emission data collected for the Ethylene Production
RTR,\65\ the EPA proposed pursuant to CAA section 112(d)(6) to require
use of the Modified El Paso Method with a leak definition of 6.2 ppmv
of total strippable hydrocarbon concentration (as methane) in the
stripping gas to further reduce HAP emissions from both new and
existing heat exchange systems, as well as to disallow delay of repair
of leaks if the measured concentration meets or exceeds 62 ppmv. Based
on an evaluation of incremental HAP cost effectiveness to increase the
monitoring frequency, the EPA proposed no changes to the monitoring
frequency in the PEPO NESHAP for monitoring for leaks from heat
exchange systems, which continues to be monthly monitoring in the first
six months following startup of a source and quarterly monitoring
thereafter. The EPA also proposed to require re-monitoring at the
relevant monitoring location after repair of a leak to ensure the
repair was successful. Further, the EPA proposed that none of these
proposed requirements for heat exchange systems apply to heat exchange
systems that have a maximum cooling water flow rate of 10 gallons per
minute or less. Finally, the EPA proposed that owners and operators may
use the current leak monitoring requirements for heat exchange systems
at 40 CFR 63.104(b) in lieu of using the Modified El Paso Method,
provided that 99 percent by weight or more of the organic compounds
that could leak into the heat exchange system are water soluble and
have a Henry's Law Constant less than 5.0E-6 atmospheres-cubic meters/
mol at 25 degrees Celsius. See section IV.C.1 of the proposal preamble
for a summary of the EPA's rationale for selecting the proposed leak
method, leak definition, and limitation on delay of repairs, as well as
the Agency's rationale for retaining the previous monitoring schedule.
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\64\ Texas Commission on Environmental Quality, Sampling
Procedures Manual, Appendix P: The Air Stripping Method (Modified El
Paso Method) for Determination of Volatile Organic Compound (VOC)
Emissions from Water Sources (included in EPA-HQ-OAR-2023-0282-0030)
describes in the detail the Modified El Paso Method. Appendix P is
included in the docket for this rulemaking.
\65\ See section II.D of the proposal preamble and the Ethylene
Production RTR rulemaking docket, Docket ID No. EPA-HQ-OAR-2017-
0357.
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For a detailed discussion of the EPA's findings, see the document
titled Clean Air Act Section 112(d)(6) Technology Review for Heat
Exchange Systems Located in the PEPO Production Source Category that
are Associated with Processes Subject to the PEPO NESHAP.\66\
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\66\ Document ID No. EPA-HQ-OAR-2023-0282-0072.
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b. Storage Vessels
In the EPA's technology review for the PEPO Production source
category, the EPA identified three control options for further reducing
emissions from PEPO storage vessels in organic HAP service. See section
IV.C.2 of the proposal preamble for a summary of the three options.
Based on the evaluation of the costs and emission reductions of each of
the three options, the EPA proposed, pursuant to CAA section 112(d)(6),
to: (1) revise the Group 1 PEPO storage vessel capacity and maximum
true vapor pressure (MTVP) thresholds to reflect the HON existing
source threshold, which requires existing storage vessels between 38
m\3\ (inclusive) and 151 m\3\ with a vapor pressure greater than or
equal to 6.9 kPa to reduce emissions of organic HAP by 95 percent
utilizing a closed vent system and control device, or to reduce organic
HAP emissions by utilizing an IFR, an external floating roof, routing
the emissions to a process or a fuel gas system, or vapor balancing;
and (2) require upgraded deck fittings and controls for guidepoles for
all storage vessels equipped with an IFR.\67\
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\67\ The EPA requires all openings in an IFR (except those for
automatic bleeder vents (vacuum breaker vents), rim space vents, leg
sleeves, and deck drains) to be equipped with a deck cover, and the
deck cover is required to be equipped with a gasket between the
cover and the deck.
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[[Page 13128]]
For a detailed discussion of the EPA's findings, see the document
titled Clean Air Act Section 112(d)(6) Technology Review for Storage
Vessels Located in the PEPO Production Source Category that are
Associated with Processes Subject to the PEPO NESHAP.\68\
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\68\ Document ID No. EPA-HQ-OAR-2023-0282-0065.
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c. Process Vents
The EPA's technology review for PEPO process vents in organic HAP
service did not identify any control options associated with: (1)
epoxide (i.e., EtO, propylene oxide, butylene oxide, and
epichlorohydrin) emissions resulting from the use of these chemicals as
reactants or (2) emissions of nonepoxide organic HAP resulting from
their use in catalyst extraction. However, the EPA identified three
emission reduction options as part of the Agency's technology review
for continuous process vents associated with nonepoxide organic HAP
from making or modifying product and process vents associated with
affected sources that produce PEPO using THF. See section IV.C.3 of the
proposal preamble for a summary of the three options. Based on the
EPA's evaluation of the costs and emission reductions of each of the
three options, the Agency proposed pursuant to CAA section 112(d)(6) to
remove the TRE index value concept in its entirety from the PEPO
NESHAP. The EPA also proposed, pursuant to CAA section 112(d)(6), to
remove the 50 ppmv and 0.005 scmm thresholds from the Group 1
definition for continuous process vents associated with nonepoxide
organic HAP and the Group 1 process vent applicability associated with
a PMPU using THF and instead to require owners and operators of these
process vents that emit greater than or equal to 1.0 lb/hr of total
organic HAP to meet the current control standards in the PEPO NESHAP.
In addition, the EPA identified one option for reducing emissions from
the combination of batch process vents that are associated with the use
of a nonepoxide organic HAP to make or modify the product.
Consequently, the EPA proposed pursuant to CAA section 112(d)(6) to
revise the PEPO NESHAP control threshold for these batch process vents
from 26,014 lb/yr to 10,000 lb/yr and to remove the associated flow
rate applicability thresholds (including the Group 1 process vent
thresholds of annual organic HAP emissions mass flow rate, cutoff flow
rate, and annual average batch vent flow rate from the definition of
``Group 1 combination of batch process vents'' specified in the PEPO
NESHAP at 40 CFR 63.1423(b)).
For a detailed discussion of the EPA's findings, see the document
titled Clean Air Act Section 112(d)(6) Technology Review for Batch and
Continuous Process Vents in the PEPO Production Source Category that
are Associated with Processes Subject to the PEPO NESHAP.\69\
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\69\ Document ID No. EPA-HQ-OAR-2023-0282-0070.
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d. Equipment Leaks
In the EPA's technology review for the PEPO Production source
category, the EPA identified three control options for further reducing
emissions from leaks of equipment in organic HAP service at PEPO
facilities. See section IV.C.5 of the proposal preamble for a summary
of the three options. Based on the EPA's evaluation of the costs and
emission reductions of each of the three options, the Agency proposed
pursuant to CAA section 112(d)(6) to revise the PEPO NESHAP to use a
leak definition of 100 ppmv for valves that are in either gas/vapor
service or light liquid service.
For a detailed discussion of the EPA's findings, see the document
titled Clean Air Act Section 112(d)(6) Technology Review for Equipment
Leaks Located in the PEPO Production Source Category that are
Associated with Processes Subject to the PEPO NESHAP.\70\
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\70\ Document ID No. EPA-HQ-OAR-2023-0282-0074.
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e. Fenceline Monitoring
In the EPA's technology review for the PEPO Production source
category, the Agency proposed a fenceline monitoring standard requiring
owners and operators to monitor for EtO if their affected source uses,
produces, stores, or emits EtO and to conduct root cause analysis and
corrective action if the affected source exceeds an annual average EtO
concentration action level of 0.2 [micro]g/m\3\. For a detailed
discussion of the EPA's findings, see the document titled Clean Air Act
Section 112(d)(6) Technology Review for Fenceline Monitoring Located at
Facilities with PEPO Production Processes Subject to the PEPO
NESHAP.\71\
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\71\ Document ID No. EPA-HQ-OAR-2023-0282-0056.
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2. How did the technology review change for the PEPO Production source
category?
Apart from the proposed requirements for continuous process vents
and fenceline monitoring, the EPA is finalizing the results of the
technology review pursuant to CAA section 112(d)(6) for the PEPO
Production source category as proposed with two minor clarifications
related to the heat exchange system and storage vessel provisions of
the review. For continuous process vent requirements, the final rule
retains the use of the TRE index value concept and the current
definition of a ``Group 1 continuous process vent.'' \72\ This
definition refers to a process vent from a continuous unit operation
that is associated with the use of a nonepoxide organic HAP to make or
modify the product and that has: (1) a flow rate greater than or equal
to 0.005 scmm, (2) a total organic HAP concentration greater than or
equal to 50 ppmv, and (3) a TRE index value less than or equal to 1.0.
Additionally, the final rule excludes all elements of the proposed
fenceline monitoring requirements. With regard to the heat exchange
system portion of the EPA's proposed technology review, the EPA is
clarifying that the PEPO NESHAP does not require owners and operators
to monitor their regulated heat exchange systems using water sampling
methods or a surrogate indicator (i.e., comply with the provisions in
either 40 CFR 63.104(b) or (c)) if the heat exchange system is
monitored for leaks using the Modified El Paso Method (according to 40
CFR 63.104(g)). For the storage vessel portion of the EPA's proposed
technology review, the Agency is allowing more time (i.e., either the
next time the storage vessel is emptied and degassed, or no later than
March 18, 2036) for owners and operators to install upgraded deck
fittings and controls for guidepoles for all storage vessels equipped
with an IFR. For more details regarding these changes to the EPA's
technology review, see section IV.B.3 of this preamble.
---------------------------------------------------------------------------
\72\ The TRE index value is derived from the cost effectiveness
associated with HAP control by a flare or thermal oxidation and is a
function of vent stream flowrate, vent stream net heating value,
hourly emissions, and a set of coefficients. The TRE index value was
first introduced in an EPA document titled Guideline Series for
Control of Volatile Organic Compound (VOC) Emissions from Air
Oxidation Processes in Synthetic Organic Chemical Manufacturing
Industry (SOCMI) (see EPA-450/3-84-015 (Dec. 1984)). The EPA
incorporated the TRE concept into the original HON (see 59 FR 19468
(Apr. 22, 1994)) and the original PEPO NESHAP rulemaking (see 64 FR
29420 (June 1, 1999)). The TRE index value is used in 40 CFR 63,
subpart G, and 40 CFR 63, subpart PPP, process vent regulations. The
TRE index value can also trigger monitoring, recordkeeping, and
reporting requirements. In general, continuous process vents with a
TRE index value equal to or less than 1.0 require control.
---------------------------------------------------------------------------
Additionally, in this final action, the EPA has reevaluated control
options under the authority of CAA section 112(d)(6) for process vents,
storage vessels, equipment, heat exchange systems, and wastewater that
emit EtO.
[[Page 13129]]
As part of this review, the EPA considered relevant comments from the
proposed CAA section 112(f)(2) analysis (which the Agency is not
finalizing in this action) that could inform or support the Agency's
current evaluation under CAA section 112(d)(6).\73\ Based on this
reassessment, the EPA is finalizing requirements for EtO-emitting
sources that reflect a higher level of control than those being
finalized under CAA section 112(d)(6) for the same types of sources in
organic HAP service that do not emit EtO. Section III.B of this
preamble describes the specific requirements for EtO emissions that the
EPA is finalizing. Section IV.B.3 of this preamble explains the
Agency's decision to finalize them under CAA section 112(d)(6).
---------------------------------------------------------------------------
\73\ In the proposal, the EPA proposed stringent EtO-specific
standards under CAA section 112(f)(2) and thus did not consider any
additional standards necessary under CAA section 112(d)(6).
---------------------------------------------------------------------------
3. What key comments did we receive that are relevant to the technology
review, and what are our responses?
The EPA received comments in support of and against the proposed
technology review. The EPA only received minor comments requesting
clarifications associated with the Agency's technology review for heat
exchange systems, storage vessels, and wastewater in organic HAP
service. Commenters argued that the Agency should not revise the leak
definition for valves in gas/vapor or light liquid service from 500 to
100 ppmv and should instead re-open and reevaluate the MACT standards
for new technologies for equipment leaks. The comments and the EPA's
specific responses to these issues are in the document titled Summary
of Public Comments and Responses for National Emission Standards for
Hazardous Air Pollutants for Polyether Polyols Production Industry,
which is in the docket for this rulemaking. Based on these comments,
the EPA is finalizing revisions (along with the minor clarifications
described in section IV.B.2 of this preamble) to require the Modified
El Paso Method for heat exchange systems, and the EPA is finalizing
revisions to the Group 1 PEPO storage vessel capacity and MTVP
thresholds and a requirement for owners and operators to upgrade deck
fittings and controls for guidepoles for all storage vessels equipped
with an IFR. For equipment leaks, the EPA is finalizing, as proposed, a
leak definition for valves in gas/vapor or light liquid service of 100
ppm. The EPA is finalizing the Agency's proposed determination that
there are currently no cost-effective developments for the organic HAP
standards for wastewater.
For continuous process vents in organic HAP service, the EPA
received numerous comments opposing the EPA's proposal under the
technology review to abandon the TRE index value concept in favor of a
1.0 lb/hr mass[hyphen]limit threshold. The EPA also received several
comments regarding the fenceline monitoring requirements that the
Agency proposed under the technology review. This section provides
summaries of and responses to the key comments received regarding: (1)
the technology review amendments proposed for continuous process vents
at existing and new affected sources associated with nonepoxide organic
HAP (from making or modifying product) and process vents associated
with existing and new affected sources that produce PEPO using THF and
(2) the proposed fenceline monitoring requirements. Comment summaries
and the EPA's responses for additional issues raised regarding the
proposed requirements resulting from the technology review for the PEPO
source category are in the document titled Summary of Public Comments
and Responses for National Emission Standards for Hazardous Air
Pollutants for Polyether Polyols Production Industry, which is in the
docket for this rulemaking.
In addition, as stated previously in this preamble, several
commenters requested that the EPA consider evaluating EtO-specific
standards (for process vents, storage vessels, equipment leaks, heat
exchange systems, and wastewater in EtO service) under CAA section
112(d)(6) instead of under CAA section 112(f)(2). As such, the EPA has
considered comments on the amendments proposed under CAA section
112(f)(2) that inform or support the Agency's current CAA section
112(d)(6) analysis. This section summarizes and responds to these
comments, presenting the outcomes and decisions from the EPA's
technology review of process vents, storage vessels, equipment leaks,
heat exchange systems, and wastewater in the PEPO Production source
category that emit EtO.
a. Continuous Process Vents in Organic HAP Service
Comment: Commenters strongly opposed the EPA's proposal to abandon
a longstanding compliance option in the PEPO NESHAP (i.e., the TRE
index value concept) for continuous process vents in organic HAP
service in favor of a 1.0 lb/hr mass-limit threshold. Commenters
provided many reasons for their opposition.
Commenters argued that removing the TRE index value concept from
the PEPO NESHAP falls outside the Agency's technology review authority,
since no significant control technology advancements had emerged since
the 2014 PEPO NESHAP review to warrant eliminating the compliance
mechanism.\74\ These commenters pointed out that the EPA had already
previously acknowledged that multiple process vents can be routed to a
single APCD and old information is not a new development. The
commenters also argued that neither a facility's voluntary control of
its Group 2 process vents nor enforcement challenges justify
eliminating the TRE index value concept from the PEPO NESHAP.
---------------------------------------------------------------------------
\74\ 79 FR 17340 (Mar. 27, 2014).
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Commenters claimed that the EPA's comparison of proposing to remove
the TRE index value concept from the PEPO NESHAP to other NESHAP that
omit the TRE index value concept was flawed from the outset. Commenters
pointed out that during the Ethylene Production rulemaking, the EPA
itself noted ``relatively few process vents,'' making any Group 1
versus Group 2 distinction largely moot. They also emphasized that the
EPA did not eliminate the TRE index value concept in its recent MON
technology review, and the generic MACT standards under 40 CFR 63,
subpart YY, continue to require TRE index value calculations for
categories with multiple vent types, underscoring the TRE index value's
ongoing regulatory relevance. Commenters also noted that while the HON
recently removed the TRE index value, industry objected to the TRE
index value's removal, in the form of comments and petitions, some of
which are still outstanding. In addition, commenters stated that many
facilities will still be required to comply with TRE-based
determinations according to their title V operating permits and
requirements under New Source Performance Standards 40 CFR 60, subparts
NNN and RRR.
Commenters also contended that the EPA had leaned too heavily on
one facility's CAA section 114 response (regarding the use of process
simulations) to paint the TRE index value concept as unduly complex.
The commenters asserted that many plants actually rely on direct source
testing to generate inputs for calculating the TRE index value; this
approach is not complex and avoids process simulation uncertainty
altogether. Commenters emphasized that the EPA had provided
[[Page 13130]]
no examples of cases in which verifying TRE index value calculations
was challenging or thwarted accurate cost[hyphen]effectiveness
determinations, and commenters pointed out that both state and Federal
programs routinely mandate intricate mathematical formulas without
issue.
Additionally, regarding the EPA's determination that some
facilities are voluntarily controlling continuous process vents that
are not required by the NESHAP, commenters highlighted that controlling
Group 2 vents is often anything but voluntary. Commenters asserted that
facilities control these types of emission streams to satisfy state or
Federal regulations, preconstruction permit conditions (such as
dispersion modeling or boilerplate requirements), Best Available
Control Technology or Lowest Achievable Emission Rate reviews, safety
protocols, or internal corporate standards. Commenters emphasized the
comprehensive usefulness of the TRE index value, explaining that it
accounts for both volumetric flow and net heating value to help
identify and prioritize the most significant emission sources.
Commenters referenced the 1994 HON preamble, in which the EPA supported
the TRE index value concept as an effective method for capturing all
relevant factors that influence emission rates.\75\
---------------------------------------------------------------------------
\75\ 59 FR 19127 (Apr. 22, 1994).
---------------------------------------------------------------------------
Commenters also argued that requiring owners and operators to route
low-emission, low-heating-value Group 2 streams to an emission control
device would produce negligible HAP reductions but would generate
carbon monoxide (CO), nitrogen oxides (NO<INF>X</INF>), and carbon
dioxide (CO<INF>2</INF>) and require significant supplemental fuel.
Finally, commenters noted that although the EPA recognized that the
cost effectiveness of replacing the TRE index value with a 1.0 lb/hr
mass[hyphen]limit threshold is nearly the same as raising the TRE index
value threshold to 5.0 (corresponding to proposed Control Options 1 and
3), the rationale behind selecting Control Option 3 was flawed for the
reasons previously outlined. Consequently, commenters urged the EPA not
to eliminate the TRE index value concept altogether. Also, some
commenters argued that the EPA has the authority to raise the TRE index
value threshold to a value that represents cost-effective control for
PEPO vents; however, they argued, the EPA's impacts analysis for
raising the threshold to a TRE index value of 5.0 overstated emissions
reductions and underestimated costs. Other commenters suggested that
the TRE index value threshold should remain at 1.0.
Response: After careful consideration of commenter feedback and
technical analysis, the EPA is not finalizing the Agency's proposal to
eliminate the TRE index value concept in the PEPO NESHAP for continuous
process vents associated with nonepoxide organic HAP from making or
modifying product and process vents associated with affected sources
that produce PEPO using THF, and the EPA is not removing the 50 ppmv
concentration and 0.005 scmm flow rate thresholds that define a ``Group
1 continuous process vent.'' As a result, the EPA also is not adopting
the proposed redefinition of a ``Group 1 continuous process vent'' as
any vent emitting greater than or equal to 1.0 lb/hr of total organic
HAP. Instead, the final rule retains the TRE index value concept as
well as the current definition of a ``Group 1 continuous process vent''
as a process vent from a continuous unit operation that is associated
with the use of a nonepoxide organic HAP to make or modify the product
and that has: (1) a flow rate greater than or equal to 0.005 scmm, (2)
a total organic HAP concentration greater than or equal to 50 ppmv, and
(3) a TRE index value less than or equal to 1.0.
In the EPA's proposal to evaluate the potential impacts of
eliminating the TRE index value concept from the PEPO NESHAP (as well
as the Agency's proposed evaluation of impacts for retaining the TRE
index value concept and the 50 ppmv and 0.005 scmm Group 1 process vent
thresholds but increasing the TRE index value threshold from 1.0 to
5.0), the EPA relied on data from approximately 50 continuous process
vents designated as Group 2, submitted by nine of the 13 HON facilities
that responded to the Agency's CAA section 114 information request. At
the time, the EPA believed that this dataset served as a reasonable
proxy, given the structural and operational similarities between PMPU
continuous process vents regulated under the PEPO NESHAP and continuous
process vents regulated under the HON. Upon further review and in light
of public comments, the EPA now has determined that it is not
appropriate to extrapolate impacts for PEPO continuous process vents
based on HON data (e.g., for evaluating the elimination of the TRE
index value concept in the PEPO NESHAP or for evaluating a change to
the TRE index value threshold in the PEPO NESHAP). In other words, the
EPA has determined that the Agency's dataset is too limited to finalize
this change. While the two source categories share certain
characteristics, there are important distinctions in process design,
emission profiles, and control strategies that limit the applicability
of HON data to PEPO operations. For example, HON sources tend to
operate under more uniform continuous processing conditions (which is
what the TRE index value applies to), whereas PEPO Production sources
mostly operate in batch processing conditions (and thus most PEPO
process vents would not be subject to the continuous process vent
standards) and exhibit greater variability in vent characteristics due
to differences in product formulations and raw material usage. Although
processes using THF to produce PEPO are generally continuous, the EPA
is not aware of any facilities currently using THF. Moreover,
facilities collected the HON Group 2 process vent data under a specific
regulatory context, and that data may not reflect the full range of
operating conditions or emission behaviors present in PMPUs. Using this
data to model the effects of removing or changing the TRE index value
with regard to the PEPO NESHAP could result in misleading conclusions,
potentially underestimating or overestimating the environmental and
compliance impacts for affected PEPO sources. Given these uncertainties
and the lack of PEPO-specific data for continuous vents to support a
robust analysis, the EPA has concluded that it would be unreasonable to
finalize the proposed changes for continuous vents and revising the TRE
index value for PEPO Production sources based on HON-derived
information.
b. Fenceline Monitoring
Comment: Commenters supported and opposed the proposed fenceline
monitoring requirements for PEPO facilities that use, produce, store,
or emit EtO. Commenters in support of fenceline monitoring stated that
fenceline monitoring is a development and key practice in the detection
and reduction of hard-to-characterize sources of emissions. These
commenters also emphasized that they have repeatedly advocated for the
application of fenceline monitoring to reduce emissions that impact
surrounding communities. Many commenters opposed the use of fenceline
monitoring and argued that fenceline monitoring was not a development
in practice, process, or control technology and that the EPA exceeded
its authority under CAA section 112(d)(6). Commenters argued that LDAR
provisions already regulate fugitive emissions, the EPA did not show
emissions reductions due to
[[Page 13131]]
fenceline monitoring in the proposal, and CAA section 112(d)(6) does
not authorize the EPA to impose standards to reduce uncertainty in
emissions estimates. A commenter also expressed concern with the
excessive annual cost of conducting canister sampling of EtO.
Response: In response to public comments and further evaluation,
the EPA is not finalizing a fenceline monitoring program for the PEPO
Production source category at this time. The EPA disagrees with
commenters' assertion that CAA section 112(d)(6) does not authorize the
proposed fenceline monitoring work practice standard. However, many
commenters raised concerns about the uncertainties and implementation
challenges associated with applying fenceline monitoring requirements
to PEPO facilities. These concerns suggest that the EPA needs to
conduct further analysis before establishing such standards, and the
EPA is deferring action until the Agency better understands those
issues.
Historically, the EPA has elected to not implement fenceline
monitoring for other chemical sector source categories when fugitive
emission standards were sufficiently stringent or when the EPA expected
other finalized provisions to enhance control or oversight of those
emissions.\76\ In the proposal, the EPA acknowledged discrepancies
between expected and measured EtO concentrations, based on fenceline
monitoring conducted for the Agency's 2022 CAA section 114 request.
While the results of this monitoring initially suggested a need for
further scrutiny of fugitive emissions, the EPA recognizes that this
data was limited to a short period of time at eight PEPO facilities,
including only two facilities that did not also have HON sources
emitting EtO, and thus might not be representative of their annual
emissions, especially considering the episodic nature of batch process
emissions associated with PEPO facilities. In this action, the EPA is
also finalizing strengthened EtO standards, as outlined in sections
IV.B.3.c through IV.B.3.f of this preamble. These updates include
improved controls for fugitive emissions from various emission sources
such as equipment leaks, storage vessels, wastewater, and heat exchange
systems. The EPA expects these enhancements to substantially reduce
fugitive emissions of EtO (and other commingled HAP) from PEPO
facilities. In light of these changes, the Agency has determined that
it needs further data to assess the overall impact of the revised
standards on fugitive emissions across the source category. The EPA
notes that the Agency retains the authority under CAA section 112(d)(6)
to reevaluate the necessity for fenceline monitoring and associated
work practices, once the Agency better understands the impacts of the
revised standards.
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\76\ See U.S. EPA, Summary of Public Comments and Responses for
the Risk and Technology Review for Ethylene Production, Document ID
No. EPA-HQ-OAR-2017-0357-0074 (Mar. 2020); U.S. EPA, Summary of
Public Comments and Responses for the Risk and Technology Review for
Miscellaneous Organic Chemical Manufacturing, Document ID No. EPA-
HQ-OAR-2018-0746-0200 (May 2020).
---------------------------------------------------------------------------
Finally, the EPA agrees with commenters that the projected annual
cost of a fenceline monitoring program for PEPO facilities (nearly $4.5
million) is not justified without a clearer understanding of the
benefits such monitoring would provide. The Agency remains committed to
ensuring effective and efficient regulation and will continue to assess
the appropriateness of fenceline monitoring as new data become
available.
Since the Agency is not finalizing a fenceline monitoring program
for the PEPO Production source category, the EPA is not responding to
comments related to the details of the proposed fenceline monitoring
program. However, summaries of all these comments are in the document
titled Summary of Public Comments and Responses for National Emission
Standards for Hazardous Air Pollutants for Polyether Polyols Production
Industry, which is in the docket for this rulemaking.
c. Process Vents and Storage Vessels in EtO Service
Comment: As previously mentioned in this preamble, several
commenters requested that the EPA consider evaluating EtO-specific
standards under CAA section 112(d)(6) instead of under CAA section
112(f)(2). Commenters broadly urged the EPA to prioritize meaningful
reductions in EtO emissions while avoiding excessive compliance costs.
More specifically, they called on the EPA to reassess the proposed 1
ppmv threshold used to define ``in ethylene oxide service'' for process
vents emitting EtO, as well as to reassess the proposed 0.1 weight
percent threshold applied to storage vessels emitting EtO. One
commenter recommended that the EPA allow owners and operators to
determine whether a storage vessel qualifies as ``in ethylene oxide
service'' based on its annual average EtO concentration, consistent
with the approach used for equipment leaks that emit EtO. A commenter
also proposed expanding the alternative method outlined in 40 CFR
63.109(b)(2) (which allows calculation of EtO concentration when fluid-
specific data is available) to include good engineering judgment and
process knowledge. Additionally, the commenter requested that owners
and operators be permitted to revise a storage vessel's EtO service
status by documenting changes in process or raw materials that
eliminate EtO service conditions.
Response: The EPA is not finalizing standards under CAA section
112(f)(2) as part of this rulemaking. For more information on this
decision, see section IV.A.4 of this preamble. Instead, as requested by
commenters, the EPA has reevaluated control options for process vents
and storage vessels in EtO service under CAA section 112(d)(6), which
requires the EPA to take into account any ``developments in practices,
processes, or control technologies'' and to consider factors such as
cost.\77\
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\77\ See section III.C of the proposal preamble for information
on how the Agency conducts technology reviews.
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Under this framework, the EPA reassessed the proposed EtO-specific
standard for process vents and storage vessels. For process vents, the
EPA proposed to define ``in ethylene oxide service'' as any vent within
a process that, when uncontrolled, contains a concentration of
undiluted EtO at or above 1 ppmv, and when combined, the sum of all
these process vents within the process would emit uncontrolled EtO
emissions greater than or equal to 5 lb/yr, or 2.27 kg/yr. The EPA
proposed that facilities could achieve compliance for process vents
``in ethylene oxide service'' by reducing EtO emissions by 99.9 percent
by weight, controlling the EtO concentration to below 1 ppmv, routing
emissions to a flare, or ensuring that total EtO emissions from all
vents in the process fall below the 5 lb/yr threshold. For storage
vessels, the EPA proposed to define ``in ethylene oxide service'' for
storage vessels to mean that the concentration of EtO in the stored
liquid is at least 0.1 percent by weight. The EPA proposed that
facilities could achieve compliance for storage vessels ``in ethylene
oxide service'' by reducing EtO emissions by 99.9 percent by weight,
controlling the EtO concentration to below 1 ppmv, or routing emissions
to a flare.
The EPA considers these compliance options for process vents and
storage vessels to represent Control Option 1 under CAA section
112(d)(6), and the Agency finds Control Option 1 feasible for PEPO
sources. Commenters indicated that achieving 99.9 percent destruction
efficiency is possible using the ECO control technique, and the EPA
[[Page 13132]]
is aware of multiple chemical facilities, including PEPO facilities,
already achieving 99.9 percent control efficiency using a thermal
oxidizer or other method. For decades, chemical facilities have used
flares to control HAP emissions and to handle emissions from a wide
variety of emission sources. Because achieving 99.9 percent destruction
efficiency can result in very low EtO emissions that are not
measurable, thus making the percent destruction efficiency difficult or
impossible to quantify, this option includes an alternative 1 ppm
standard to demonstrate compliance. Reducing EtO in the streams to 1
ppmv represents the lower end of measurable emissions. However, the EPA
understands that changing the process vent definition (to include any
gaseous streams ``in ethylene oxide service'') will require control of
vents that currently are not routed to controls before release to the
atmosphere. Retrofitting some of these vents could be difficult,
requiring installation of different piping and additional equipment
such as gas movers to successfully route low-flow or intermittent
streams. While commenters recommended looking at changing the proposed
concentration threshold for process vents ``in ethylene oxide
service,'' the EPA finds that concentrations can vary and may not
correlate well with overall emissions from the vent stream. From stack
testing information submitted in response to the EPA's CAA section 114
request, the Agency identified two vacuum jet process vents at one unit
that have intermittent flows of less than 25 minutes per batch.
Assuming batches are completed every 10 hours, the EPA estimated that
these process vents emit 48 lb/yr combined. The EPA additionally
assumed that two additional process vents in the PMPU would also be
low-flow or intermittent streams, e.g., from certain surge control
vessels. Therefore, to avoid technical and implementation challenges
associated with capturing very small amounts of EtO emissions from
process vents, the EPA identified a second control option, which
mirrors the proposed option except that it raises the threshold of ``in
ethylene oxide service'' from 5 lb/yr to 100 lb/yr of combined
uncontrolled EtO emissions, and it changes the control option from 5
lb/yr to 100 lb/yr of combined controlled and uncontrolled EtO
emissions. Similarly, for storage vessels, the EPA understands that
there could be storage vessels storing PEPO products with low levels of
unreacted EtO, so Control Option 2 also raises the percent by weight
threshold in the definition of ``in ethylene oxide service'' from 0.1
percent by weight to 1 percent by weight to address this concern.
To assess the impacts of the two control options, the EPA updated
the Agency's proposal analysis. The EPA relied on data from the 2017
National Emissions Inventory (NEI) and identified 11 PEPO facilities
with processes that emit EtO from process vents and/or storage vessels.
In addition to the NEI, the EPA incorporated information from several
other sources, including stack test results submitted in response to
the Agency's CAA section 114 request, full questionnaire responses from
each facility, and relevant air permits. The EPA acknowledges that a
commenter recommended applying the percent-by-weight threshold on an
annual average basis. However, because the commenter provided no
rationale or supporting explanation, the EPA did not include this
suggestion in the Agency's analysis. Additionally, the EPA notes that
demonstrating compliance with an annual average would likely require
continuous sampling of materials, which could impose significant
operational and resource burdens on facilities.
Based on this comprehensive dataset, the EPA estimated that Control
Option 1 would affect nine PEPO facilities, while Control Option 2
would impact seven PEPO facilities. For each of these facilities, the
EPA calculated the cost of installing a new recuperative thermal
oxidizer with 70 percent energy recovery, using the methodology
outlined in the EPA Control Cost Manual.\78\ The EPA used a total
capital investment estimate of $1,000,000, a value that commenters
provided during the HON rulemaking.\79\ For the final rule, the EPA's
impact analysis was revised to reflect 2024 dollars and an interest
rate of 7.5 percent over a 20-year period in the capital recovery
factor for thermal oxidizers. See the document titled Updated Impact
Calculations and Technology Review for the PEPO Production Source
Category--Final Rule, which is in the docket for this rulemaking, for
details on the assumptions and methodologies used in this analysis.
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\78\ U.S. EPA, 2002. EPA Control Cost Manual (6th ed. Jan. 2002)
(EPA/452/B-02-001).
\79\ See 89 FR 42932 (May 16, 2024).
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Table 2 of this preamble presents the nationwide impacts for the
two control options considered for the final rule for process vents and
storage vessels in EtO service.
Table 2--Nationwide Emissions Reductions and Cost Impacts of Control Options Considered for Process Vents and
Storage Vessels in EtO Service at PEPO Facilities
----------------------------------------------------------------------------------------------------------------
EtO emission EtO cost
Control option Total capital Total annualized reductions effectiveness
investment ($) costs ($/yr) (tpy) ($/ton)
----------------------------------------------------------------------------------------------------------------
1............................................. 7,056,000 2,700,000 10.8 250,000
2............................................. 5,040,000 1,957,000 10.4 188,200
----------------------------------------------------------------------------------------------------------------
The EPA finds that Control Option 2 offers meaningful EtO emissions
reductions (i.e., over 95 percent of EtO emission reductions projected
for Control Option 1 would still be achieved) at a more reasonable cost
than Control Option 1 and addresses commenters' concerns with technical
implementation challenges. Importantly, Control Option 2 targets the
larger sources of EtO emissions. Although the EPA's cost estimates
conservatively assume that many facilities would need to install a new
thermal oxidizer, the added flexibilities in Control Option 2 may
reduce that number, further reducing the compliance burden. By aligning
the storage vessel applicability threshold with that finalized for
equipment leaks (i.e., a 1.0 weight percent EtO concentration or
greater; see section IV.B.3.d of this preamble), this approach
simplifies compliance and the determination of whether storage vessels
and associated equipment fall within the scope of ``in ethylene oxide
service.'' Additionally, the cost effectiveness of Control Option 2 is
within the range of values associated
[[Page 13133]]
with finalized regulatory options in recent rulemakings regulating EtO
emissions, such as the commercial sterilizers NESHAP.\80\ We also note
that the cost-effectiveness of Control Option 2 is within the range of
historically accepted cost-effectiveness values for highly toxic HAP
(such as hexavalent chromium).\81\ Therefore, the EPA is finalizing,
pursuant to CAA section 112(d)(6), at 40 CFR 63.1423(b) the term ``in
ethylene oxide service'' for process vents to mean each process vent in
a process that, when uncontrolled, contains a concentration of greater
than or equal to 1 ppmv undiluted EtO, and when combined, the sum of
all these process vents within the process would emit uncontrolled EtO
emissions greater than or equal to 100 lb/yr (45.4 kg/yr). The EPA also
is updating the definition of ``process vent'' in the final rule at 40
CFR 63.1423(b) to align with this change. The EPA also is finalizing in
the PEPO NESHAP at 40 CFR 63.1423(b) the term ``in ethylene oxide
service'' for storage vessels to mean that the concentration of EtO in
the stored liquid is greater than or equal to 1.0 percent by weight.
The EPA also is finalizing, as proposed, that the exemption for
``vessels and equipment storing and/or handling material that contains
no organic HAP, or organic HAP as impurities only'' listed in the
definition of ``storage vessel'' at 40 CFR 63.1423(b) does not apply
for storage vessels in EtO service.
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\80\ In 2024, the EPA finalized multiple EtO emissions standards
under CAA section 112(d)(6) for commercial sterilization facilities
that had cost-effectiveness estimates of approximately $2,000,000
per ton of EtO (see 89 FR 24090 (Apr. 5, 2024)).
\81\ For small hard chromium electroplating, the EPA finalized a
requirement with a cost effectiveness of $15,000 per pound
($30,000,000 per ton) to provide an ample margin of safety (see 77
FR 58227-28 and 58239 (Sept. 19, 2012)).
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In addition, the EPA is finalizing, as proposed, the procedures for
determining whether process vents and/or storage vessels in EtO service
meet the definition of the term ``in ethylene oxide service,'' by
reference to 40 CFR 63.109 for PEPO process vents and storage vessels
in EtO service. The EPA is finalizing at 40 CFR 63.1425(g) a
requirement that PEPO process vents in EtO service reduce emissions of
EtO by either: (1) venting emissions through a closed vent system to a
non-flare control device that reduces EtO by at least 99.9 percent by
weight, to a concentration less than 1 ppmv for each process vent, or
to less than 100 lb/yr for all combined process vents within the
process, or (2) routing emissions through a closed vent system to a
flare meeting the flare operating requirements at 40 CFR 63.1436 that
the EPA is finalizing as proposed and as discussed in section IV.C of
this preamble. At 40 CFR 63.1432(s)--by reference to the HON (i.e., 40
CFR 63.138(b)(3) and (c)(3)) and accounting for differences between the
HON and the PEPO NESHAP--the EPA is finalizing that PEPO storage
vessels in EtO service reduce emissions of EtO by either: (1) venting
emissions through a closed vent system to a non-flare control device
that reduces EtO by at least 99.9 percent by weight or to a
concentration less than 1 ppmv for each storage tank vent, or (2)
venting emissions through a closed vent system to a flare meeting the
flare operating requirements at 40 CFR 63.1436 that the EPA is
finalizing, as proposed, and discussed in section IV.C of this
preamble. The EPA is also finalizing procedures to determine compliance
with these EtO standards at 40 CFR 63.1426(g) (by reference to 40 CFR
63.124 for PEPO process vents in EtO service and accounting for
differences between the HON and the PEPO NESHAP) and 40 CFR
63.1432(s)(3) (by reference to 40 CFR 63.124 for PEPO storage vessels
in EtO service and accounting for differences between the HON and the
PEPO NESHAP).
Notably, the EPA disagrees with the commenters' requests to allow
for good engineering judgment and process knowledge in 40 CFR
63.109(b)(2) to determine whether a storage vessel qualifies as ``in
ethylene oxide service'' or to allow documentation of changes to the
process or raw materials to revise the determination. The final
definition of ``in ethylene oxide service'' lets an owner or operator
designate emission points based on process knowledge; however, if an
owner or operator wants to say an emission point is not in EtO service,
they must use the procedures in 40 CFR 63.109. The EPA is allowing good
engineering judgment at 40 CFR 63.109(c)(2) (for equipment leaks) and
(e) (for heat exchange systems) due to the difficulty and issues with
sampling and testing fluid in process lines, particularly if the fluid
contains EtO. Additionally, the rule already explicitly allows an owner
or operator to calculate the concentration of EtO of the fluid stored
in the storage vessels if information specific to the fluid stored,
including data based on safety data sheets, is available.
Comment: Some commenters opposed the EPA's proposal at 40 CFR
63.1427(a) that owners and operators may not use the ECO pollution
prevention technique to show compliance with the proposed standard for
PEPO process vents in EtO service. Commenters stated that they
routinely use the ECO option to reduce epoxide emissions and that the
ECO option provides an efficient and cost-effective means to control
epoxide emissions without secondary emissions or the additional energy
consumption of a traditional control device.
A commenter stated that regulated entities should have the
flexibility to perform ECO or to shorten the batch cycle and install
emission control equipment as both options reduce EtO emissions. The
commenter disagreed with the EPA's justification that achieving a 99.9
percent reduction of EtO from an onset of 1 ppmv is not practical using
ECO and said that the proposed provision does not require a 99.9
percent reduction of EtO from a 1 ppmv onset. Instead, the commenter
expressed that, in order to meet the treatment target for a process
vent in EtO service, ECO would only need to achieve either a 99.9
percent reduction of EtO emissions or a concentration of 1 ppmv of EtO
in the process vent. Additionally, the commenter argued that the EPA
did not support the statement that the use of ECO could lead to high
EtO emissions relative to the starting amount of epoxide used.
To support their argument, the commenter provided information on
emissions reductions as a result of using ECO as an emissions control
technique. The information showed that for two products, ECO can
achieve 99.9 percent reductions in EtO emissions based on the
commenter's analysis. In addition, the commenter submitted a more
detailed economic analysis as confidential business information to show
when ECO is no longer economically feasible.
A different commenter acknowledged that while the economic
breakpoint may have changed since the EPA originally promulgated the
procedures to determine the onset, they disagree with the EPA's
assertion that ECO is no longer economically viable and noted the
conclusion was drawn from a single response to the EPA's CAA section
114 request. The commenter requested a discussion with the EPA on ways
to revise the onset determination in 40 CFR 63.1427(c) while retaining
the necessary emissions reductions and economic viability of the ECO
option.
Another commenter said that the EPA did not provide adequate
explanation to support elimination of the ECO option. They said that
facilities should have the option to determine on their own whether use
of ECO is economically viable. Additionally, the commenter noted that
their facility only uses the ECO option while venting to a control
device so that EtO emissions are
[[Page 13134]]
controlled to required limits regardless of the starting amount of
epoxide used.
Response: The EPA has reevaluated the use of ECO as a control
technique to comply with EtO process vent standards. Although customer
specifications for PEPO products increase the economic incentive to
continue the reaction until less than 1 ppm EtO remains in the product,
post-reaction steps could remove the EtO. Therefore, the traditional
determination of economic breakpoint (i.e., comparing the cost of the
unreacted EtO to the cost of the reduced productivity of the reactor)
is still relevant. The EPA would need more information to update the
appropriate starting point of ECO under current economic conditions.
Thus, given these uncertainties, the EPA is not finalizing the proposed
elimination of ECO as a compliance option for the EtO process vent
standards at this time.
d. Equipment Leaks in EtO Service
Comment: As previously mentioned in this preamble, several
commenters requested that the EPA consider evaluating EtO-specific
standards under CAA section 112(d)(6) instead of under CAA section
112(f)(2). For equipment that emits EtO, to minimize burden, commenters
specifically requested that the EPA reduce the proposed monthly
connector monitoring frequency and revise the proposed 0.1 weight
percent EtO concentration threshold in the definition of equipment ``in
ethylene oxide service.'' Commenters indicated that there are
significant logistical challenges to monitor all connectors monthly due
to the large number of connectors that require monitoring. Commenters
stated that gasket failure is the primary reason for connector leaks
and, once repaired, connectors have a low frequency of repeat leaks. In
addition, the commenters emphasized that monitoring connectors monthly
would be particularly difficult if a facility is shut down for a
portion of the month, as all connectors would need to be monitored
within a 15-day period. Commenters recommended quarterly connector
monitoring and encouraged the EPA to consider annual or semiannual
connector monitoring frequencies. Commenters also stated that the EPA
did not provide a reasonable justification to define equipment ``in
ethylene oxide service'' at such a low concentration (i.e., 0.1 weight
percent EtO) and recommended that the EPA use a higher concentration
threshold.
Response: The EPA is not finalizing standards under CAA section
112(f)(2) as part of this rulemaking. For more information on this
decision, see section IV.A.4 of this preamble. Instead, as requested by
commenters, the EPA has reevaluated control options for equipment leaks
in EtO service under CAA section 112(d)(6), which requires the EPA to
take into account any ``developments in practices, processes, or
control technologies'' and to consider factors such as cost.
Under this framework, to assess what standards may be appropriate
for equipment that leak EtO, the EPA considered previously reviewed
information for existing LDAR programs for the chemical manufacturing
industry discussed in the proposal and assessed the comments received
during the public comment period. As part of that review, the EPA noted
that two rules require control of leak emissions from equipment ``in
ethylene oxide service.'' In the HON and MON rulemakings, the EPA added
EtO-specific requirements for equipment in EtO service. These rules'
requirements for equipment ``in ethylene oxide service'' are more
stringent than for equipment in organic HAP service.\82\ Other
regulations, permits, and voluntary initiatives have similarly
structured LDAR programs (i.e., with a defined monitoring frequency and
leak definition) for a variety of chemical manufacturing facilities.
For example, some chemical manufacturing area source facilities perform
monthly or quarterly monitoring for EtO at leak definitions of 50 ppmv
or 100 ppmv.\83\
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\82\ 89 FR 42932 (May 16, 2024); 85 FR 49084 (Aug. 12, 2020).
\83\ Chemical manufacturing area source facility LDAR program
details are available in U.S. EPA, Clean Air Act Section 112(d)(5)
GACT Standard Analysis for Equipment Leaks that Emit Ethylene Oxide
and Section 112(d)(6) Technology Review for Equipment Leaks from
Chemical Manufacturing Process Units at Area Sources Subject to the
CMAS NESHAP, Document ID No. EPA-HQ-OAR-2024-0303-0027, appendix B.
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Given the EtO-specific requirements in the HON and MON, the
similarities in controlling equipment leak emissions across chemical
manufacturing facilities, and the issues and recommendations provided
by commenters (i.e., commenters expressed that monthly monitoring was
especially burdensome for connectors and recommended a reduced
frequency, while also urging the EPA to target equipment with higher
potential EtO emissions by raising the EtO concentration threshold for
the LDAR program), the EPA evaluated six control options under CAA
section 112(d)(6) for PEPO equipment that emit EtO for the final rule.
The first option is the same control option the EPA proposed for the
PEPO NESHAP under CAA section 112(f)(2), which reflects the same EtO
standard for equipment in EtO service subject to the HON. The first
option defines equipment ``in ethylene oxide service'' as containing or
contacting a fluid (liquid or gas) that contains at least 0.1 percent
by weight EtO. Owners or operators achieve compliance for equipment
``in ethylene oxide service'' by performing monthly monitoring at a
leak definition of 100 ppmv for gas/vapor and light liquid connectors
and gas/vapor and light liquid valves and at a leak definition of 500
ppmv for light liquid pumps. The other five control options involve the
impact of changing the EtO concentration threshold from 0.1 to 1
percent by weight EtO and changing the monitoring frequencies for
connectors (from monthly to quarterly, semiannual, and annual) and for
valves (from monthly to quarterly). The light liquid pump monitoring
frequencies and leak definitions are the same for all the control
options the EPA evaluated. Connectors account for almost 70 percent of
all components at a PEPO PMPU; any reduction in their required
monitoring frequency would substantially lower the time commitment and
costs needed for PEPO facilities to comply with an LDAR standard for
equipment leaks that emit EtO emissions.
The six EtO equipment leak control options the EPA evaluated for
the final rule are:
<bullet> Control Option 1: 0.1 percent by weight EtO concentration
threshold: monthly monitoring at 100 ppmv for gas/vapor and light
liquid connectors and gas/vapor and light liquid valves, monthly
monitoring at 500 ppmv for light liquid pumps (the proposed option);
<bullet> Control Option 2: 1 percent by weight EtO concentration
threshold: monthly monitoring at 100 ppmv for gas/vapor and light
liquid connectors and gas/vapor and light liquid valves, monthly
monitoring at 500 ppmv for light liquid pumps;
<bullet> Control Option 3: 1 percent by weight EtO concentration
threshold: quarterly monitoring at 100 ppmv for gas/vapor and light
liquid connectors, monthly monitoring at 100 ppmv for gas/vapor and
light liquid valves, monthly monitoring at 500 ppmv for light liquid
pumps;
<bullet> Control Option 4: 1 percent by weight EtO concentration
threshold: quarterly monitoring at 100 ppmv for gas/vapor and light
liquid connectors and gas/vapor and light liquid valves, monthly
monitoring at 500 ppmv for light liquid pumps;
<bullet> Control Option 5: 1 percent by weight EtO concentration
threshold: semiannual monitoring at 100 ppmv for
[[Page 13135]]
gas/vapor and light liquid connectors, quarterly monitoring at 100 ppmv
for gas/vapor and light liquid valves, monthly monitoring at 500 ppmv
for light liquid pumps; and
<bullet> Control Option 6: 1 percent by weight EtO concentration
threshold: maintain monitoring frequencies from the current PEPO
requirements for non-EtO equipment, 100 ppmv leak definition for gas/
vapor and light liquid connectors and gas/vapor and light liquid
valves, 500 ppmv leak definition for light liquid pumps.
To assess the impacts of these control options, the EPA relied on
data received pursuant to the Agency's CAA section 114 request. The EPA
first assessed the impact of increasing the EtO threshold from 0.1 to 1
percent by weight EtO. The EPA does not have sufficient data to fully
define the population of equipment between 0.1 and 1 percent by weight
EtO (i.e., EtO concentration data are not available for individual
pieces of equipment). However, the EPA approximated this impact based
on PEPO PMPU-level EtO concentration data. While a PMPU likely would
have a combination of equipment that is above and below a 1 percent by
weight EtO threshold, the responses to the EPA's CAA section 114
request only provided data to make this determination at the PEPO PMPU-
level. The EPA determined that two PEPO PMPUs have an average EtO
concentration less than 1 percent by weight EtO and excluded these
PMPUs entirely from the Agency's analyses when assessing the control
options that used a threshold of 1 percent by weight EtO (i.e., Control
Options 2 through 6). The EPA otherwise applied the same methodology to
estimate the costs and emissions reduction for the final rule as
applied for the proposal. For the final rule, the EPA's impact analysis
reflects 2024 dollars, and the Agency used an interest rate of 7.5
percent to calculate capital recovery factors. See the document titled
Updated Impact Calculations and Technology Review for the PEPO
Production Source Category--Final Rule, which is in the docket for this
rulemaking, for details on the assumptions and methodologies the EPA
used in this analysis.
Table 3 of this preamble presents the nationwide impacts for the
control options considered for the final rule for equipment in EtO
service. Table 3 shows the control options ordered from most stringent
to least stringent; the incremental cost effectiveness shown for each
option is in comparison to the next control option in the table.
Table 3--Nationwide Emissions Reductions and Cost Impacts of Control Options Considered for Equipment in EtO
Service at PEPO Facilities
----------------------------------------------------------------------------------------------------------------
Incremental
Total capital Total EtO emission EtO cost EtO cost
Control option investment annualized reductions effectiveness effectiveness
($) costs ($/yr) (tpy) ($/ton) ($/ton)
----------------------------------------------------------------------------------------------------------------
1............................... $113,000 $1,740,000 22.1 $78,900 $248,000
2............................... 65,400 1,220,000 20.0 60,900 289,000
3............................... 65,400 497,000 17.5 28,300 53,500
4............................... 65,400 235,000 12.6 18,700 38,700
5............................... 65,400 91,800 8.9 10,300 9,680
6............................... 65,400 16,300 1.1 15,100 ..............
----------------------------------------------------------------------------------------------------------------
While the cost effectiveness values of all the control options are
within the range of values associated with finalized regulatory options
in recent rulemakings regulating EtO emissions, such as the commercial
sterilizers NESHAP,\84\ and are within the range of historically
accepted cost-effectiveness values for highly toxic HAP (such as
hexavalent chromium),\85\ the EPA is finalizing Control Option 3 in
lieu of the other control options evaluated, including Control Option 1
(the proposed option). The EPA is finalizing Control Option 3 to add an
EtO-specific LDAR standard in the PEPO NESHAP for equipment in EtO
service pursuant to CAA section 112(d)(6) because this option offers
meaningful emissions reductions while significantly reducing compliance
burdens (e.g., compared to Control Option 1). As illustrated in Table 3
of this preamble, the EPA projects that Control Options 6, 5, 4, and 3
incrementally achieve increased EtO emissions reductions with steadily
increasing annual costs associated with the increased monitoring
frequencies. However, between Control Options 3 and 2 (i.e., increasing
connector monitoring frequency from quarterly to monthly), there is a
significant jump in the annual cost without a similarly significant
improvement to EtO emissions reductions. Additionally, Control Option 3
has annual costs 72 percent lower than Control Option 1, but the
emission reductions are only 21 percent lower. Industry stakeholders
also have emphasized the importance of targeting substantial sources of
EtO emissions without imposing unnecessary logistical challenges that
are not fully captured in the overall annual costs. For example,
commenters pointed to certain maintenance situations that could limit
the time available to conduct monthly connector monitoring to only a
week or two--a situation that, while infrequent, the EPA is unable to
fully account for in its costs analyses. The EPA also recognizes that
emissions reductions benefits result from focusing attention and
efforts on the equipment with higher potential for large emissions of
EtO (i.e., equipment prior to the polymerization reaction, which would
contain process fluids with higher EtO content).
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\84\ See 89 FR 24090 (Apr. 5, 2024).
\85\ See 77 FR 58227-28 and 58239 (Sept. 19, 2012).
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Therefore, pursuant to CAA section 112(d)(6), the EPA is finalizing
at 40 CFR 63.1423(b) the term ``in ethylene oxide service'' for
equipment to mean any equipment that contains or contacts a fluid
(liquid or gas) that is at least 1.0 percent by weight EtO. In
addition, the EPA is finalizing requirements for quarterly monitoring
at a leak definition of 100 ppmv for gas/vapor and light liquid
connectors in EtO service, monthly monitoring at a leak definition of
100 ppmv for gas/vapor and light liquid valves in EtO service, and
monthly monitoring at a leak definition of 500 ppmv for light liquid
pumps in EtO service, at 40 CFR 63.1434(a)(3), by reference to the HON
and accounting for the differences between the HON and the PEPO NESHAP.
Comment: Several commenters opposed the EPA's proposal to disallow
the use of delay of repair for equipment in EtO service. The commenters
said that the EPA's proposed elimination of delay of repair will
increase emissions of EtO, increase costs, and eliminate
[[Page 13136]]
needed flexibility for facilities to operate in a continuous manner
without frequent shutdowns.
Commenters stated that lead times for shutdowns provide adequate
time for facilities to order and test components but if the delay of
repair provisions are eliminated for equipment in EtO service, the
required lead times will result in extended shutdowns. The commenters
asserted that while small EtO leaks may be able to be mitigated by off-
the-shelf solutions, these cannot be used in every instance and finding
an alternative can take more than the proposed 15-day repair window.
One commenter stated that taking a tank out of service is a monumental
task that is bound by strict process requirements due to safety
concerns. The commenter said that requiring expedited shutdowns would
pose serious safety hazards for workers due to the volatile nature of
EtO.
Commenters stated that if the EPA's intent is to reduce EtO
emissions from PEPO facilities, the Agency should continue to allow
delay of repair, at least in situations where delaying repair would
result in fewer EtO emissions than shutting down. A commenter also
noted that the EPA did not quantify any potential emissions reductions
associated with delay of repair. The commenter expressed that if the
EPA had accounted for the emissions reductions from elimination of the
delay of repair provisions, the analysis would show that more frequent
shutdown events would lead to emissions of approximately 5 to 340
pounds of EtO per event. The commenter provided an example where a leak
repair would have to be delayed for 10 years before emissions exceeded
those of a shutdown event.
A commenter recommended that the EPA consider alternatives if the
full delay of repair provisions cannot be retained. The commenter
proposed that the EPA allow owners or operators to delay repair for no
more than five total components in EtO service and not allow repair
delay for any component with a leak greater than or equal to 1,000
ppmv. According to the commenter, their proposed alternative would
ensure that a minimal number of components would be on delay of repair
status at any one time and that none of those components would have
large leaks while providing facilities with flexibility needed to avoid
unplanned shutdowns.
Response: For equipment in EtO service, the EPA is finalizing
repair of leaks as soon as practicable but no later than 15 days after
the leak is detected, with delay of repair allowed in limited
circumstances, at 40 CFR 63.1434(a)(3)(iv). To address commenters'
concerns that some equipment in EtO service would be difficult to
repair without requiring a process shutdown and disrupting production,
the EPA is not finalizing the proposed removal of delay of repair
allowances for leaking equipment in EtO service. Instead, the EPA is
maintaining the delay of repair requirements for equipment in organic
HAP service at 40 CFR 63.171 as well as incorporating suggestions from
commenters to create additional enforceable guardrails for equipment in
EtO service to limit EtO emissions from leaks. These guardrails include
restricting the number of components in EtO service that can be put on
delay of repair status at a time, requiring continued monitoring of any
equipment in EtO service on delay of repair status, and finalizing a
leak action level that, if exceeded during the initial or continued
monitoring, would no longer allow the repair to be delayed and would
instead require repair consistent with the equipment leak requirements
(i.e., repaired no later than 15 calendar days after the leak action
level is exceeded).
For PEPO production sources, the EPA believes that the additional
guardrails in this action for delaying repair of equipment in EtO
service would significantly reduce the need for unscheduled shutdowns
and continue to ensure achievement of the projected emission reductions
from the revised equipment leak standards for equipment in EtO service.
First, based on commenter suggestions, the EPA is limiting the number
of components in EtO service in a PMPU that can be put on delay of
repair to no more than five components at a time. To accommodate PMPUs
with more than 5,000 pieces of equipment in EtO service, where the
number of components that could be difficult to repair without a
shutdown could increase proportionally, the EPA is alternatively
allowing delay of repair of no more than 0.1 percent of the components
in EtO service (rounded up to the next highest whole number). Second,
the EPA is requiring that PEPO sources conduct monthly monitoring for
any piece of equipment in EtO service on delay of repair to ensure the
leak remains small. Consistent with comments, the EPA is finalizing a
leak action level of 1,000 ppm for equipment in EtO service to ensure
that owners or operators will quickly fix larger leaks. Owners or
operations would need to repair equipment that they find is leaking at
or above the 1,000 ppm action level no later than 15 calendar days
after the leak action level is exceeded. This includes monthly
monitoring events for equipment on delay of repair. If a leak grows
such that a monthly monitoring event reveals that equipment placed on
delay of repair is now leaking above the leak action level, the owner
or operator of that piece of equipment can no longer delay repair.
Instead, the owner or operator will need to fix the leak no later than
15 calendar days after detection of the leak action level exceedance.
Lastly, the EPA is allowing PEPO production sources to delay repair of
equipment in EtO service if the owner or operator can isolate the
equipment from the process such that the equipment does not remain in
EtO service, similar to the requirements in 40 CFR 63.171(b). These
isolated pieces of equipment would not count toward the five components
or 0.1 percent of components calculation nor be subject to the
continued monthly leak monitoring or leak action level, since the
equipment would no longer have the potential to emit EtO.
Comment: Some commenters opposed the EPA's proposal to disallow
skip periods for monitoring equipment in EtO service. One commenter
expressed that removing skip periods increases costs for industry
without reductions in emissions. The commenter cited the CAA section
114 data and stated that seven out of nine process units in EtO service
for which the EPA had data indicated that there were no leaks detected
in 2017, and thus, the Agency cannot justify the elimination of skip
periods, given low initial leak rates. With respect to connectors
specifically, the commenter claimed that they have a lower leak rate
than valves and pumps, and that once repaired, there is a low frequency
of repeat leaks. The commenter said that it is a waste of resources to
monitor the same connectors every month if the facilities have low leak
frequencies.
Another commenter suggested that instead of removing skip periods
for gas/vapor and light liquid valves in EtO service, the EPA should
use an approach similar to 40 CFR part 60, subparts VV, VVa, and VVb
(i.e., monitor monthly for two successive months and then monitor the
first month of every subsequent quarter until a leak is detected). The
commenter said that this approach would allow their facilities to focus
resources on valves with leaks greater than 100 ppmv and not have to
continue monitoring all valves on a monthly basis. Alternatively, the
commenter recommended that owners and operators be allowed to subdivide
valves in gas/vapor or light liquid
[[Page 13137]]
service into two or three subgroups where, instead of monitoring all
valves the first month of every quarter, each subgroup may be monitored
in a different month, so long as each subgroup is monitored every three
months.
Response: The EPA is finalizing specific monitoring frequencies
consistent with its CAA section 112(d)(6) review and is not allowing
skip periods for equipment in EtO service. Leaks are often random by
nature, and the EPA has determined that consistent monitoring
frequencies are necessary to ensure that the LDAR standard maintains
the level of stringency evaluated for the technology review.
Additionally, because the EPA is not finalizing fenceline monitoring
requirements for EtO in this final rule, it is even more critical to
ensure by other means that owners or operators control fugitive
emissions to the intended level, and skip periods could lead to
prolonged emissions from a random leak that owners or operators did not
find due to a lack of monitoring. For connectors, as discussed earlier
in this section, the EPA has changed monitoring frequency in the final
rule to quarterly instead of monthly, as proposed. This change
addresses the biggest challenge indicated by commenters and alleviates
concerns about the potential impact of removing skip frequencies and
requiring monthly connector monitoring. Considering all these factors
and the cost effectiveness of the standard, the EPA is not allowing
skip periods for equipment in EtO service.
e. Heat Exchange Systems in EtO Service
Comment: As previously mentioned in this preamble, several
commenters requested that the EPA consider evaluating EtO-specific
standards under CAA section 112(d)(6) instead of under CAA section
112(f)(2). Commenters declared that the proposed requirements for heat
exchange systems that emit EtO were above and beyond what is
appropriate and necessary to control EtO emissions. Commenters stated
that the EPA's proposal to conduct weekly monitoring using the Modified
El Paso Method is an undue, repetitive strain on personnel with little
environmental benefit. Instead, commenters recommended that the EPA
consider either monthly or quarterly monitoring options. Commenters
also urged the EPA to consider setting a concentration threshold for
EtO above the proposed 0.1 weight percent when determining which heat
exchangers qualify as being ``in ethylene oxide service.'' One
commenter suggested that the current monitoring frequency and
concentration threshold for PEPO heat exchangers in organic HAP service
(i.e., quarterly monitoring, applicable to heat exchangers that contain
a process fluid that is at least 5 weight percent organic HAP) are
sufficient to control EtO emissions from heat exchangers.
Response: The EPA is not finalizing standards under CAA section
112(f)(2) as part of this rulemaking. For more information on this
decision, see section IV.A.4 of this preamble. Instead, as requested by
commenters, the EPA has reevaluated control options for heat exchange
systems in EtO service under the CAA section 112(d)(6) authority, which
requires the EPA to take into account any ``developments in practices,
processes, or control technologies'' and to consider factors such as
cost.
Under this framework, to identify and evaluate standards that may
be appropriate for heat exchange systems that emit EtO, the EPA
considered previously reviewed information from other rulemakings for
the chemical manufacturing industry, assessed the public comments, and
considered the new requirements for PEPO heat exchange systems in
organic HAP service that the EPA is finalizing in this action. The EPA
identified use of the Modified El Paso Method to monitor for heat
exchange system leaks multiple times, although the specific
requirements vary. The EPA assessed two control options for heat
exchange systems that emit EtO. To start, as discussed in sections
IV.B.1 and IV.B.2 of this preamble, the EPA proposed and are finalizing
that heat exchange systems in organic HAP service must use the Modified
El Paso Method.\86\
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\86\ In organic HAP service means the heat exchanger contains a
process fluid that is 5 percent or greater by weight organic HAP.
---------------------------------------------------------------------------
The EPA first reassessed the same control option the Agency
proposed for the PEPO NESHAP under CAA section 112(f)(2). At proposal,
the EPA identified one rule requiring control of emissions from heat
exchange systems ``in ethylene oxide service.'' In the 2024 HON
rulemaking, the EPA added EtO-specific requirements for heat exchange
systems in EtO service.\87\ There are minimal operational differences
between controlling heat exchange system emissions from HON chemical
manufacturing process units (CMPUs) and PEPO PMPUs. As such, Control
Option 1 reflects the same control option the EPA proposed for the PEPO
NESHAP under CAA section 112(f)(2) and also reflects the exact same EtO
standard for heat exchange systems in EtO service subject to the HON.
Control Option 1 defines ``in ethylene oxide service'' for heat
exchange systems as any heat exchange system in a process that cools
process fluids (liquid or gas) that are 0.1 percent or greater by
weight of EtO. Under Control Option 1, compliance for heat exchange
systems ``in ethylene oxide service'' is achieved by conducting weekly
monitoring using the Modified El Paso Method and repairing leaks of
total strippable hydrocarbon concentration (as methane) in the
stripping gas of 6.2 ppmv or greater within 15 days from the sampling
date, with no delay of repair allowed.
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\87\ 89 FR 42932 (May 16, 2024).
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In response to commenters' concerns that the proposed control
requirements for heat exchange systems in EtO service may be
unnecessarily stringent (particularly in light of the EPA's
acknowledgment that the 2017 NEI contained no reported EtO leaks), the
Agency also evaluated an alternative approach, Control Option 2. This
option mirrors Control Option 1 in regulating heat exchange systems
``in ethylene oxide service'' but introduces key distinctions that
offer greater flexibility. Most notably, in Control Option 2, the EPA
raises the percent by weight threshold in the definition of ``in
ethylene oxide service'' from 0.1 percent by weight to 1 percent by
weight and require monthly (instead of weekly) monitoring using the
Modified El Paso Method. The EPA recognizes that there are benefits to
focusing attention and efforts on heat exchange systems that have a
higher potential for large leaks of EtO because they service process
fluids with higher EtO content; thus, the EPA evaluated a 1 percent by
weight threshold to represent the EtO content expected in process
fluids (cooled by the heat exchange system) prior to the polymerization
reaction. Control Option 2 also requires repairing leaks of total
strippable hydrocarbon concentration (as methane) in the stripping gas
of 6.2 ppmv or greater within 45 days and allows delay of repair in
certain circumstances as it encompasses a delay of repair action level
of total strippable hydrocarbon concentration (as methane) in the
stripping gas of 62 ppmv--a level that, if exceeded during leak
monitoring, would require immediate repair (i.e., the leak found cannot
be put on delay of repair and would be required to be repaired within
30 days of the monitoring event). Given the absence of data on the
prevalence and magnitude of EtO leaks from heat exchange systems in EtO
service at
[[Page 13138]]
PEPO sources, the EPA agrees with commenters that increasing the
frequency of monitoring (e.g., going from monthly monitoring in Control
Option 2 to weekly monitoring in Control Option 1) might not yield
meaningful emissions reductions and that any additional modeled
reductions appear to be minimal. Further, in evaluating Control Option
2, the EPA recognizes that less frequent monitoring could alleviate
burdens on LDAR technicians and that providing flexibility to delay
repairs may help facilities avoid unnecessary process shutdowns.
To assess the impacts of the two control options, the EPA assumed
that the provisions would affect all 20 PEPO facilities with processes
that use and emit EtO. As part of the EPA's analysis, the Agency
assumed that owners or operators conducting monitoring for three or
more heat exchange systems would elect to purchase a stripping column
and flame ionization detector analyzer and perform in-house Modified El
Paso Method monitoring, because the total annualized costs for in-house
Modified El Paso Method monitoring are less than the costs for
contracted services. In addition, the EPA assumed that owners or
operators could repair leaks by plugging a specific heat exchanger
tube, and if a heat exchanger is leaking to the extent that it needs
replacing, then it is effectively at the end of its useful life.
Therefore, the EPA determined that the cost of replacing a heat
exchanger is an operational cost that the owner or operator would incur
as a result of routine maintenance and equipment replacement and not
attributable to the control option. For the final rule, the EPA's
impact analysis reflects 2024 dollars. The EPA also used an interest
rate of 7.5 percent over a 5-year period in the capital recovery factor
for the useful life of a quality assurance plan and/or Modified El Paso
Method monitoring system (depending on whether the monitoring is
contracted out or performed in-house). See the document titled Updated
Impact Calculations and Technology Review for the PEPO Production
Source Category--Final Rule, which is in the docket for this
rulemaking, for details on the assumptions and methodologies used in
this analysis.
Table 4 of this preamble presents the nationwide impacts for the
two control options considered for the final rule for heat exchange
systems in EtO service.
Table 4--Nationwide Emissions Reductions and Cost Impacts of Control Options Considered for Heat Exchange
Systems in EtO Service at PEPO Facilities
----------------------------------------------------------------------------------------------------------------
Total capital EtO emission EtO cost
Control option investment Total annualized reductions effectiveness
($) costs ($/yr) (tpy) ($/ton)
----------------------------------------------------------------------------------------------------------------
1 (weekly).................................... 200,200 326,000 11.3 29,000
2 (monthly)................................... 200,200 73,000 11.1 6,600
----------------------------------------------------------------------------------------------------------------
Although Control Option 1 could be considered to be cost effective,
there is uncertainty in the prevalence of heat exchange system leaks
and commenters have identified potential disruptions associated with
requiring operations and lab staff to conduct monitoring activities
every week and to repair potentially complex equipment without
allowances for delays. The EPA is finalizing Control Option 2 to add
EtO standards in the PEPO NESHAP for heat exchange systems in EtO
service pursuant to CAA section 112(d)(6) because it is lower cost and
provides similar reductions to Option 1. However, the EPA observes that
the conclusion that it is necessary under CAA section 112(d)(6) to
require Option 2 based on the estimated costs and reductions is
uncertain. For example, our analysis did not consider leak data from
smaller heat exchangers such as those used in the PEPO source category.
Accordingly, we intend to reconsider this control option to allow for a
more complete understanding of these sources and their EtO emissions.
The EPA's intent to reconsider will also allow us to ensure full
consideration of similar provisions currently being reconsidered in the
HON, a related chemical sector NESHAP frequently cross-referenced by
the PEPO NESHAP. Pursuant to CAA section 112(d)(6), the EPA is
finalizing at 40 CFR 63.1423(b) the term ``in ethylene oxide service''
for heat exchange systems to mean any heat exchange system in a process
that cools process fluids (liquid or gas) that are 1.0 percent or
greater by weight of EtO. In addition, the EPA is finalizing monthly
monitoring for leaks for heat exchange systems in EtO service using the
Modified El Paso Method at 40 CFR 63.1435(a), which references the HON
(i.e., 40 CFR 63.104(g)(6)) and accounts for differences between the
HON and the PEPO NESHAP. If the owner or operator finds a leak, the EPA
is requiring repair of the leak to reduce the concentration or mass
emissions rate below the applicable leak action level as soon as
practicable but no later than 45 days after collecting the sample, with
delay of repair allowed based on a delay of repair action level of
total strippable hydrocarbon concentration (as methane) in the
stripping gas of 62 ppmv--a level that, if exceeded during leak
monitoring, would require immediate repair (i.e., the leak found cannot
be put on delay of repair and would be required to be repaired within
30 days of the monitoring event).\88\
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\88\ See 40 CFR 63.1435(a), which references the HON (i.e., 40
CFR 63.104(h)(6)) and accounts for differences between the HON and
the PEPO NESHAP.
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f. Wastewater in EtO Service
Comment: As previously discussed in this preamble, several
commenters requested that the EPA consider evaluating EtO-specific
standards under CAA section 112(d)(6) instead of under CAA section
112(f)(2). For wastewater that emits EtO, commenters suggested that the
standard should focus on streams with higher concentrations and higher
overall amounts of EtO. Commenters strongly opposed the EPA's proposed
EtO concentration threshold of 1 ppmw in the definition of wastewater
streams ``in ethylene oxide service'' and stated that there would be
significant costs to control streams at this low concentration with
minimal impact on emission reductions. Commenters further contended
that the EPA should account for the total mass of EtO present in
wastewater streams. They suggested that regulating only those streams
exceeding a specific mass threshold could achieve substantial emission
reductions while limiting the number of streams requiring control.
Response: The EPA is not finalizing standards under CAA section
112(f)(2) as part of this rulemaking. For more information on this
decision, see section IV.A.4 of this preamble. Instead, as requested by
commenters, the EPA has reevaluated control options for wastewater in
EtO service under the
[[Page 13139]]
CAA section 112(d)(6) authority, which requires the Agency to take into
account any ``developments in practices, processes, or control
technologies'' and to consider factors such as cost.
Under this framework, to assess what standards may be appropriate
for wastewater emitting EtO, the EPA considered previously reviewed
information for wastewater controls from other rulemakings and
considered the public comments. As part of that review, the EPA noted
one rule requiring control of emissions from wastewater ``in ethylene
oxide service.'' In the HON rulemaking, the EPA added EtO-specific
requirements for wastewater in EtO service; the requirements for
wastewater ``in ethylene oxide service'' are more stringent than for
wastewater in organic HAP service.\89\
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\89\ 89 FR 42932 (May 16, 2024).
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Given the EtO-specific requirements in the HON, the minimal
operational differences between controlling emissions from HON CMPUs
and PEPO PMPUs, and the issues and recommendations provided by
commenters (i.e., focus on streams with higher EtO concentrations and
higher overall amounts of EtO), the EPA evaluated two control options
under CAA section 112(d)(6) for PEPO wastewater that emit EtO for the
final rule. The first option is the same control option the EPA
proposed for the PEPO NESHAP under CAA section 112(f)(2), which
reflects the same EtO standard for wastewater in EtO service subject to
the HON. This option defines ``in ethylene oxide service'' for
wastewater as any wastewater stream that contains total annual average
concentration of EtO greater than or equal to 1 ppmw at any flow rate,
and a wastewater stream in EtO service is considered a Group 1
wastewater stream. Under Control Option 1, facilities achieve
compliance for wastewater ``in ethylene oxide service'' by reducing, by
removal or destruction, the concentration of EtO to a level less than 1
ppmw.
In response to commenter feedback urging the EPA to target
wastewater streams with higher EtO concentrations and total EtO
amounts, the Agency evaluated Control Option 2 for the final rule. This
option mirrors Control Option 1 in regulating wastewater ``in ethylene
oxide service'' but introduces key distinctions that offer greater
flexibility. Most notably, in Control Option 2, the EPA raises the EtO
concentration threshold that triggers control requirements from 1 ppmw
to 10 ppmw, based on commenters' suggestions that the Agency consider
raising the threshold and consider wastewater control requirements
similar to those in 40 CFR part 61, subpart FF, which has a threshold
of 10 ppmw (for benzene, the pollutant regulated in subpart FF). This
means that only wastewater streams with EtO concentrations at or above
10 ppmw would be subject to control under Control Option 2, whereas
Control Option 1 applies to streams with concentrations as low as 1
ppmw. The data from the CAA section 114 request show that PEPO
wastewater streams reported with EtO concentrations below 10 ppmw
contribute a small amount (less than 0.1 percent) to the overall
wastewater EtO load and EtO emissions. This provision distinguishes
Control Option 2 from Control Option 1 by prioritizing regulatory focus
on streams with higher EtO concentrations and total emissions, where
control measures are likely to be more effective at achieving emissions
reductions. In response to commenter feedback urging the EPA to
consider a total source EtO mass flow rate threshold in the final rule
(e.g., commenters recommended alignment with standards like 40 CFR part
61, subpart FF, that contain a total source mass flow rate threshold),
Control Option 2 also introduces an exemption for wastewater streams in
EtO service that is not part of Control Option 1. Specifically, Control
Option 2 includes an exemption for wastewater streams in EtO service
that cumulatively contain less than 1 megagram (approximately 1.1 tons)
of EtO per year, thus excluding low-volume streams from control
requirements.
Additionally, the EPA understands that the proposed compliance
option (i.e., reduce the concentration of EtO of each wastewater
stream, by removal or destruction, to a level less than 1 ppmw), could
be difficult to achieve for streams with a high EtO load. Therefore,
the EPA is expanding the compliance pathways to allow facilities to
choose between using three different performance standards for
treatment processes, including reducing the concentration of EtO of
each wastewater stream, by removal or destruction, to a level less than
1 ppmw, or complying with the Group 1 wastewater stream requirements
outlined in 40 CFR 63.138(d) or (e). Per 40 CFR 63.138(d), the owner or
operator must operate and maintain a steam stripper that meets certain
design requirements. Per 40 CFR 63.138(e), the owner or operator must
reduce, by removal or destruction, the mass flow rate of EtO by at
least 98 percent. Although EtO is biodegradable, its low
biodegradability factor indicates that conventional biological
treatment alone would only reduce its concentration by about half.\90\
Therefore, additional treatment, such as steam stripping, is necessary
to reliably remove the remaining EtO from the wastewater. With any of
these compliance options, the EPA expects that facilities would use
steam stripping to control the wastewater streams, but facilities would
have more flexibility in demonstrating compliance. Regardless of the
compliance option an owner or operator chooses, they still must comply
with the applicable control device requirements in 40 CFR 63.139 and 40
CFR 63.145(i) and (j) when venting gases from the treatment process, as
well as the applicable leak inspection provisions in 40 CFR 63.148.
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\90\ EtO has a fraction emitted (Fe) factor of 0.5. The Fe is
the mass fraction of a HAP emitted from the wastewater collection
and downstream biological treatment system. Fe is an indicator of
the fraction of a compound expected to be an air emission out of
wastewater in typical chemical sector collection and treatment
systems.
---------------------------------------------------------------------------
To assess the impacts of the two control options, the EPA used
information for 24 PEPO wastewater streams (each containing a total
annual average concentration of EtO greater than or equal to 1 ppmw)
that four PEPO facilities that received the CAA section 114 request
provided to the EPA. Using this comprehensive dataset, the EPA
estimated that both control options would affect five PEPO facilities
(i.e., all four PEPO facilities that received the CAA section 114
request plus one additional PEPO facility). Importantly, for the final
rule, the EPA implemented procedures for addressing ambiguity in
certain reported EtO concentrations by interpreting reported values
(from the CAA section 114 request) that contained a ``less than''
symbol for values reported as ``<1,000'' and ``<100'' as one order of
magnitude lower than stated. For instance, if a respondent reported a
value as ``<1,000,'' the EPA's approach for the final rule assumed the
actual value to be ``100.'' The EPA's underlying rationale for this
approach is that if the respondent had intended to indicate a value
below 100, they would have explicitly reported it as ``<100'' rather
than using the broader ``<1,000'' threshold. This method ultimately
provides a conservative estimate of impacts that accounts for ambiguity
in the data.
The EPA calculated the cost of installing a steam stripper using
the cost algorithm for wastewater steam stripper requirements, used for
the development of the HON, for each of the five PEPO facilities that
the Agency determined
[[Page 13140]]
the two control options would impact.\91\ For the final rule, the
impact analysis reflects 2024 dollars. The EPA also uses an interest
rate of 7.5 percent over a 20-year period in the capital recovery
factor for steam strippers. See the document titled Updated Impact
Calculations and Technology Review for the PEPO Production Source
Category--Final Rule, which is in the docket for this rulemaking, for
details on the assumptions and methodologies the EPA used in this
analysis.
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\91\ U.S. EPA, Hazardous Air Pollutant Emissions from Process
Units in the Synthetic Organic Chemical Manufacturing Industry--
Background Information for Proposed Standards, vol. 1C: Model
Emission Sources (Nov. 1992) (EPA-453/D-92-016c).
---------------------------------------------------------------------------
Table 5 of this preamble presents the nationwide impacts for the
two control options considered for the final rule for wastewater in EtO
service.
Table 5--Nationwide Emissions Reductions and Cost Impacts of Control Options Considered for Wastewater in EtO
Service at PEPO Facilities
----------------------------------------------------------------------------------------------------------------
Total capital EtO emission EtO cost
Control option investment Total annualized reductions effectiveness
($) costs ($/yr) (tpy) ($/ton)
----------------------------------------------------------------------------------------------------------------
1............................................. 14,100,000 5,500,000 38.2 144,000
2............................................. 13,600,000 5,200,000 37.2 140,000
----------------------------------------------------------------------------------------------------------------
While the cost effectiveness values of both control options are
within the range of values associated with finalized regulatory options
in recent rulemakings regulating EtO emissions, such as the commercial
sterilizers NESHAP,\92\ and are within the range of historically
accepted cost-effectiveness values for highly toxic HAP (such as
hexavalent chromium \93\), the EPA is finalizing Control Option 2 in
lieu of Control Option 1. The EPA is finalizing Control Option 2 to add
EtO standards in the PEPO NESHAP for wastewater in EtO service pursuant
to CAA section 112(d)(6) because this option offers meaningful
emissions reductions while significantly reducing compliance burdens,
compared to Control Option 1. Commenters have emphasized the importance
of targeting substantial sources of EtO emissions without imposing
unnecessary complexity on facilities managing smaller sources. The EPA
recognizes that requiring control of minor EtO sources can introduce
implementation challenges, which the EPA has mitigated by refining the
definition of ``in ethylene oxide service.''
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\92\ See 89 FR 24090 (Apr. 5, 2024).
\93\ See 77 FR 58227-28 and 58239 (Sept. 19, 2012).
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For wastewater ``in ethylene oxide service,'' the EPA's data
indicate that the revised criteria (i.e., Control Option 2) would
exclude at least 30 percent of the wastewater streams in EtO service
that the proposed rule (i.e., Control Option 1) would have affected.
The EPA's analysis indicates that a small subset of wastewater streams
accounts for the majority of EtO emissions at most PEPO facilities. In
contrast, low-flow, low-concentration, or intermittent streams
contribute minimally to EtO emissions at most PEPO facilities and are
often subject to significant variability, making consistent control
both technically challenging and potentially inefficient.
Overall, the EPA believes Control Option 2 strikes a balance
between meaningful emissions reductions and practical implementation,
making it a sound choice despite having a similar cost to Control
Option 1. Therefore, pursuant to CAA section 112(d)(6) the EPA is
finalizing at 40 CFR 63.1423(b) the term ``in ethylene oxide service''
for wastewater to mean any wastewater stream that contains total annual
average concentration of EtO greater than or equal to 10 ppmw at any
flow rate. The EPA is also updating the definition of ``wastewater'' in
the final rule at 40 CFR 63.1423(b) to align with this change. In
addition, the EPA is finalizing, as proposed, the procedures for
determining whether a wastewater stream is in EtO service within the
definition of the term ``in ethylene oxide service'' by reference to 40
CFR 63.109 for PEPO wastewater streams in EtO service. The EPA also is
finalizing at 40 CFR 63.1433(s)(23) a requirement--by reference to the
HON and accounting for differences between the HON and the PEPO
NESHAP--that owners and operators must reduce the concentration of EtO
of each wastewater stream, by removal or destruction, to a level less
than 1 ppmw, or comply with the Group 1 wastewater stream control
requirements outlined in 40 CFR 63.138(d) or (e). Additionally, the EPA
is finalizing an exemption to this requirement at 40 CFR
63(s)(23)(iii)(D) for wastewater streams in EtO service that
cumulatively contain less than 1 megagram (approximately 1.1 tons) of
EtO per year, where the owner or operator annually samples the exempted
wastewater streams to verify that they are below this threshold. The
EPA also is finalizing language at 40 CFR 63.1433(s)(23) to clarify
that if an owner or operator elects to either reduce the EtO
concentration in each wastewater stream to below 1 ppmw or achieve at
least a 98 percent reduction in EtO mass flow rate, they must conduct a
performance test to demonstrate compliance instead of a design
evaluation. Alternatively, if the owner or operator chooses to operate
and maintain a steam stripper that meets the design specifications
outlined in 40 CFR 63.138(d), the EPA is not requiring a performance
test or design evaluation.
4. What is the rationale for our final approach and final decisions for
the technology review?
The EPA's technology review focused on the identification and
evaluation of developments in practices, processes, and control
technologies that have occurred since the EPA promulgated the previous
technology review for the PEPO NESHAP.\94\ Specifically, the EPA
focused the technology review on all existing MACT standards for the
various emission sources in the PEPO Production source category,
including heat exchange systems, storage vessels, process vents,
wastewater, and equipment leaks in organic HAP service. In the
proposal, the EPA identified cost-effective developments for PEPO heat
exchange systems, storage vessels, process vents, and equipment leaks,
and the Agency proposed revising the standards for these four emissions
sources under the technology review. The EPA did not identify
developments in practices, processes, or control technologies for
wastewater in organic HAP service. For managing fugitive emissions, the
EPA also proposed a fenceline monitoring work practice standard under
the technology review. Further information regarding the
[[Page 13141]]
technology review is in the proposed rule and in the supporting
materials in the rulemaking docket.
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\94\ See 59 FR 17340 (Mar. 27, 2014).
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[…truncated; see source link]Indexed from Federal Register on March 18, 2026.
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.