`[Federal Register Volume 90, Number 13 (Wednesday, January 22, 2025)]
[Proposed Rules]
[Pages 7942-7991]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2025-00685]



[[Page 7941]]

Vol. 90

Wednesday,

No. 13

January 22, 2025

Part IV





Environmental Protection Agency





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40 CFR Part 63





National Emission Standards for Hazardous Air Pollutants: Chemical 
Manufacturing Area Sources Technology Review; Proposed Rule

  Federal Register / Vol. 90 , No. 13 / Wednesday, January 22, 2025 / 
Proposed Rules  

[[Page 7942]]


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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 63

[EPA-HQ-OAR-2024-0303; FRL-7623-01-OAR]
RIN 2060-AU73


National Emission Standards for Hazardous Air Pollutants: 
Chemical Manufacturing Area Sources Technology Review

AGENCY: Environmental Protection Agency (EPA).

ACTION: Proposed rule.

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SUMMARY: The Environmental Protection Agency (EPA) is proposing to 
establish a new area source category to address chemical manufacturing 
process units (CMPUs) using ethylene oxide (EtO). The EPA is proposing 
to list EtO in table 1 to the National Emission Standards for Hazardous 
Air Pollutants (NESHAP) for Chemical Manufacturing Area Sources 
(referred to as the CMAS NESHAP in this document) and to add EtO-
specific requirements to the CMAS NESHAP. The EPA is also proposing to 
add a fenceline monitoring program for EtO. In addition, the EPA is 
proposing new requirements for pressure vessels and pressure relief 
devices (PRDs). This proposal also presents the results of the EPA's 
technology review of the CMAS NESHAP as required under the Clean Air 
Act (CAA). As part of this technology review, the EPA is proposing to 
add new leak detection and repair (LDAR) requirements to the CMAS 
NESHAP for equipment leaks in organic HAP service and heat exchange 
systems. The EPA is also proposing performance testing once every 5 
years and to add provisions for electronic reporting. We estimate that 
the proposed amendments to the CMAS NESHAP, excluding the proposed EtO 
emission standards, would reduce hazardous air pollutant (HAP) 
emissions from emission sources by approximately 158 tons per year 
(tpy). Additionally, the proposed EtO emission standards are expected 
to reduce EtO emissions by approximately 4.6 tpy.

DATES: 
    Comments. Comments must be received on or before March 24, 2025. 
Under the Paperwork Reduction Act (PRA), comments on the information 
collection provisions are best assured of consideration if the Office 
of Management and Budget (OMB) receives a copy of your comments on or 
before February 21, 2025.
    Public hearing: If anyone contacts us requesting a public hearing 
on or before January 27, 2025 we will hold a virtual public hearing. 
See SUPPLEMENTARY INFORMATION for information on requesting and 
registering for a public hearing.

ADDRESSES: You may send comments, identified by Docket ID No. EPA-HQ-
OAR-2024-0303, by any of the following methods:
     Federal eRulemaking Portal: https://www.regulations.gov/ 
(our preferred method). Follow the online instructions for submitting 
comments.
     Email: [email protected]. Include Docket ID No. EPA-
HQ-OAR-2024-0303 in the subject line of the message.
     Fax: (202) 566-9744. Attention Docket ID No. EPA-HQ-OAR-
2024-0303.
     Mail: U.S. Environmental Protection Agency, EPA Docket 
Center, Docket ID No. EPA-HQ-OAR-2024-0303, Mail Code 28221T, 1200 
Pennsylvania Avenue NW, Washington, DC 20460.
     Hand/Courier Delivery: EPA Docket Center, WJC West 
Building, Room 3334, 1301 Constitution Avenue NW, Washington, DC 20004. 
The Docket Center's hours of operation are 8:30 a.m.-4:30 p.m., Monday-
Friday (except Federal Holidays).
    Instructions: All submissions received must include the Docket ID 
No. for this rulemaking. Comments received may be posted without change 
to https://www.regulations.gov/, including any personal information 
provided. For detailed instructions on sending comments and additional 
information on the rulemaking process, see the SUPPLEMENTARY 
INFORMATION section of this document.

FOR FURTHER INFORMATION CONTACT: For questions about this proposed 
action, contact U.S. EPA, Attn: Mr. William Gallagher, Mail Drop: E143-
01, 109 T.W. Alexander Drive, P.O. Box 12055, RTP, North Carolina 
27711; telephone number: (919) 541-2336; and email address: 
[email protected].

SUPPLEMENTARY INFORMATION: Participation in virtual public hearing. To 
request a virtual public hearing, contact the public hearing team at 
(888) 372-8699 or by email at [email protected]. If requested, 
the hearing will be held via virtual platform. The EPA will announce 
the date of the hearing and further details at https://www.epa.gov/stationary-sources-air-pollution/chemical-manufacturing-area-sources-national-emission-standards. The hearing will convene at 11:00 a.m. 
Eastern Time (ET) and will conclude at 4:00 p.m. ET. The EPA may close 
a session 15 minutes after the last pre-registered speaker has 
testified if there are no additional speakers.
    The EPA will begin pre-registering speakers for the hearing no 
later than 1 business day after a request has been received. To 
register to speak at the virtual hearing, please use the online 
registration form available at https://www.epa.gov/stationary-sources-air-pollution/chemical-manufacturing-area-sources-national-emission-standards or contact the public hearing team at (888) 372-8699 or by 
email at [email protected]. The last day to pre-register to 
speak at the hearing will be February 3, 2025. Prior to the hearing, 
the EPA will post a general agenda that will list pre-registered 
speakers at: https://www.epa.gov/stationary-sources-air-pollution/chemical-manufacturing-area-sources-national-emission-standards.
    The EPA will make every effort to follow the schedule as closely as 
possible on the day of the hearing; however, please plan for the 
hearings to run either ahead of schedule or behind schedule.
    Each commenter will have 4 minutes to provide oral testimony. The 
EPA encourages commenters to submit a copy of their oral testimony as 
written comments to the rulemaking docket.
    The EPA may ask clarifying questions during the oral presentations, 
but will not respond to the presentations at that time. Written 
statements and supporting information submitted during the comment 
period will be considered with the same weight as oral testimony and 
supporting information presented at the public hearing.
    Please note that any updates made to any aspect of the hearing will 
be posted online at https://www.epa.gov/stationary-sources-air-pollution/chemical-manufacturing-area-sources-national-emission-standards. While the EPA expects the hearing to go forward as set forth 
above, please monitor these websites or contact the public hearing team 
at (888) 372-8699 or by email at [email protected] to determine 
if there are any updates. The EPA does not intend to publish a document 
in the Federal Register announcing updates.
    If you require the services of a translator or a special 
accommodation such as audio description, please pre-register for the 
hearing with the public hearing team and describe your needs by January 
29, 2025. The EPA may not be able to arrange accommodations without 
advanced notice.
    Docket. The EPA has established a docket for this rulemaking under 
Docket ID No. EPA-HQ-OAR-2024-0303. All

[[Page 7943]]

documents in the docket are listed in https://www.regulations.gov/. 
Although listed, some information is not publicly available, e.g., 
Confidential Business Information (CBI) or other information whose 
disclosure is restricted by statute. Certain other material, such as 
copyrighted material, is not placed on the internet and will be 
publicly available only in hard copy. With the exception of such 
material, publicly available docket materials are available 
electronically in https://www.regulations.gov/.
    Instructions. Direct your comments to Docket ID No. EPA-HQ-OAR-
2024-0303. The EPA's policy is that all comments received will be 
included in the public docket without change and may be made available 
online at https://www.regulations.gov/, including any personal 
information provided, unless the comment includes information claimed 
to be CBI or other information whose disclosure is restricted by 
statute. Do not submit electronically to https://www.regulations.gov/ 
any information that you consider to be CBI or other information whose 
disclosure is restricted by statue. This type of information should be 
submitted as discussed below.
    The EPA may publish any comment received to its public docket. 
Multimedia submissions (audio, video, etc.) must be accompanied by a 
written comment. The written comment is considered the official comment 
and should include discussion of all points you wish to make. The EPA 
will generally not consider comments or comment contents located 
outside of the primary submission (i.e., on the Web, cloud, or other 
file sharing system). For additional submission methods, the full EPA 
public comment policy, information about CBI or multimedia submissions, 
and general guidance on making effective comments, please visit https://www.epa.gov/dockets/commenting-epa-dockets.
    The https://www.regulations.gov/ website allows you to submit your 
comment anonymously, which means the EPA will not know your identity or 
contact information unless you provide it in the body of your comment. 
If you send an email comment directly to the EPA without going through 
https://www.regulations.gov/, your email address will be automatically 
captured and included as part of the comment that is placed in the 
public docket and made available on the internet. If you submit an 
electronic comment, the EPA recommends that you include your name and 
other contact information in the body of your comment and with any 
digital storage media you submit. If the EPA cannot read your comment 
due to technical difficulties and cannot contact you for clarification, 
the EPA may not be able to consider your comment. Electronic files 
should not include special characters or any form of encryption and be 
free of any defects or viruses. For additional information about the 
EPA's public docket, visit the EPA Docket Center homepage at https://www.epa.gov/dockets.
    Submitting CBI. Do not submit information containing CBI to the EPA 
through https://www.regulations.gov/. Clearly mark the part or all of 
the information that you claim to be CBI. For CBI information on any 
digital storage media that you mail to the EPA, note the docket ID, 
mark the outside of the digital storage media as CBI, and identify 
electronically within the digital storage media the specific 
information that is claimed as CBI. In addition to one complete version 
of the comments that includes information claimed as CBI, you must 
submit a copy of the comments that does not contain the information 
claimed as CBI directly to the public docket through the procedures 
outlined in Instructions above. If you submit any digital storage media 
that does not contain CBI, mark the outside of the digital storage 
media clearly that it does not contain CBI and note the docket ID. 
Information not marked as CBI will be included in the public docket and 
the EPA's electronic public docket without prior notice. Information 
marked as CBI will not be disclosed except in accordance with 
procedures set forth in 40 Code of Federal Regulations (CFR) part 2.
    Our preferred method to receive CBI is for it to be transmitted 
electronically using email attachments, File Transfer Protocol (FTP), 
or other online file sharing services (e.g., Dropbox, OneDrive, Google 
Drive). Electronic submissions must be transmitted directly to the 
Office of Air Quality Planning and Standards (OAQPS) CBI Office at the 
email address [email protected] and, as described above, should include 
clear CBI markings and note the docket ID. If assistance is needed with 
submitting large electronic files that exceed the file size limit for 
email attachments, and if you do not have your own file sharing 
service, please email [email protected] to request a file transfer link. 
If sending CBI information through the postal service, please send it 
to the following address: U.S. EPA, Attn: OAQPS Document Control 
Officer, Mail Drop: C404-02, 109 T.W. Alexander Drive, P.O. Box 12055, 
RTP, North Carolina 27711, Attention Docket ID No. EPA-HQ-OAR-2024-
0303. The mailed CBI material should be double wrapped and clearly 
marked. Any CBI markings should not show through the outer envelope.
    Preamble acronyms and abbreviations. Throughout this preamble the 
use of ``we,'' ``us,'' or ``our'' is intended to refer to the EPA. We 
use multiple acronyms and terms in this preamble. While this list may 
not be exhaustive, to ease the reading of this preamble and for 
reference purposes, the EPA defines the following terms and acronyms 
here:

ACC American Chemistry Council
ACS American Community Survey
ADAF age-dependent adjustment factor
AFPM American Fuels and Petrochemical Manufacturers
APCD air pollution control device
API American Petroleum Institute
AVO audio, visual, and olfactory
BACT best available control technology
CAA Clean Air Act
CBI Confidential Business Information
CEDRI Compliance and Emissions Data Reporting Interface
CFR Code of Federal Regulations
CMAS Chemical Manufacturing Area Source(s)
CMPU chemical manufacturing process unit
CO carbon monoxide
CO2 carbon dioxide
EAV equivalent annualized value
EFR external floating roof
EIS Emissions Inventory System
EJ environmental justice
EMACT Ethylene Production MACT
EPA Environmental Protection Agency
ERT Electronic Reporting Tool
EtO ethylene oxide
FID flame ionization detector
FR Federal Register
GACT generally available control technologies
HAP hazardous air pollutant(s)
HON Hazardous Organic NESHAP
HQ hazard quotient
HRVOC highly reactive volatile organic compound
ICR information collection request
IFR internal floating roof
IRIS Integrated Risk Information System
km kilometer(s)
kPa kilopascal(s)
LAER lowest achievable emission rate
lb pound(s)
lb/yr pound(s) per year
LDAR leak detection and repair
MACT maximum achievable control technology
MIR maximum individual lifetime [cancer] risk
MON Miscellaneous Organic Chemical Manufacturing NESHAP
MTVP maximum true vapor pressure
NAICS North American Industry Classification System
NATA National Air Toxics Assessment
NEI National Emissions Inventory
NESHAP national emission standards for hazardous air pollutants
NOX nitrogen oxides
N2O nitrous oxide

[[Page 7944]]

NPRA National Petrochemical and Refiners Association
NSPS new source performance standards
OAQPS Office of Air Quality Planning and Standards
OAR Office of Air and Radiation
OLD Organic Liquids Distribution
OMB Office of Management and Budget
P&R I Group I Polymers and Resins
PDF portable document format
PEPO Polyether Polyols Production
PM2.5 particulate matter 2.5
PMPU polyether polyol manufacturing process unit
ppmv parts per million by volume
ppmw parts per million by weight
PRA Paperwork Reduction Act
PRD pressure relief device
PV present value
RACT reasonably available control technology
RDL representative detection limit
RFA Regulatory Flexibility Act
RTR risk and technology review
SOCMI Synthetic Organic Chemical Manufacturing Industry
SO2 sulfur dioxide
TCEQ Texas Commission on Environmental Quality
TOC total organic compounds
TOSHI target organ-specific hazard index
tpy tons per year
TRE total resource effectiveness
UMRA Unfunded Mandates Reform Act
U.S.C. United States Code
VCS voluntary consensus standards
VOC volatile organic compound(s)
[micro]g/m3 micrograms per cubic meter

    Organization of this document. The information in this preamble is 
organized as follows:

I. General Information
    A. Does this action apply to me?
    B. Where can I get a copy of this document and other related 
information?
II. Background
    A. What is the statutory authority for this action?
    B. What are the source categories and how does the current 
NESHAP regulate HAP emissions?
    C. What data collection activities were conducted to support 
this action?
    D. What other relevant background information and data are 
available?
    E. What are the results of the EPA's risk assessment?
III. Analytical Procedures and Decision-Making
    A. How do we determine GACT?
    B. How do we perform the technology review?
IV. Analytical Results and Proposed Decisions
    A. What are our proposed decisions regarding standards 
representing GACT for EtO emissions from CMAS, and what is the 
rationale for those decisions?
    B. What are our other proposed decisions regarding GACT 
standards for CMAS, and what is the rationale for those decisions?
    C. What are the results and proposed decisions based on our 
technology review, and what is the rationale for those decisions?
    D. What other actions are we proposing, and what is the 
rationale for those actions?
    E. What compliance dates are we proposing, and what is the 
rationale for the proposed compliance dates?
V. Summary of Cost, Environmental, and Economic Impacts
    A. What are the affected sources?
    B. What are the air quality impacts?
    C. What are the cost impacts?
    D. What are the economic impacts?
    E. What are the benefits?
    F. What analysis of environmental justice did we conduct?
    G. What analysis of children's environmental health did we 
conduct?
VI. Request for Comments
    VII. Statutory and Executive Order Reviews
    A. Executive Order 12866: Regulatory Planning and Review and 
Executive Order 14094: Modernizing Regulatory Review
    B. Paperwork Reduction Act (PRA)
    C. Regulatory Flexibility Act (RFA)
    D. Unfunded Mandates Reform Act (UMRA)
    E. Executive Order 13132: Federalism
    F. Executive Order 13175: Consultation and Coordination With 
Tribal Governments
    G. Executive Order 13045: Protection of Children From 
Environmental Health Risks and Safety Risks
    H. Executive Order 13211: Actions Concerning Regulations That 
Significantly Affect Energy Supply, Distribution, or Use
    I. National Technology Transfer and Advancement Act (NTTAA) and 
1 CFR Part 51
    J. Executive Order 12898: Federal Actions To Address 
Environmental Justice in Minority Populations and Low-Income 
Populations and Executive Order 14096: Revitalizing Our Nation's 
Commitment to Environmental Justice for All

I. General Information

A. Does this action apply to me?

    The source categories that are the subject of this proposal are 
Agricultural Chemicals and Pesticides Manufacturing, Chemical 
Manufacturing with Ethylene Oxide, Cyclic Crude and Intermediate 
Production, Industrial Inorganic Chemical Manufacturing, Industrial 
Organic Chemical Manufacturing, Inorganic Pigments Manufacturing, 
Miscellaneous Organic Chemical Manufacturing, Plastic Materials and 
Resins Manufacturing, Pharmaceutical Production, and Synthetic Rubber 
Manufacturing, regulated under 40 CFR part 63, subpart VVVVVV. The 
North American Industry Classification System (NAICS) code for the 
chemical manufacturing operations at any of the ten chemical 
manufacturing area source (CMAS) categories is 325. This list of 
categories and NAICS codes is not intended to be exhaustive, but rather 
provides a guide for readers regarding the entities that this proposed 
action is likely to affect. The proposed standards, once promulgated, 
will be directly applicable to the affected sources. Federal, state, 
local, and Tribal government entities would not be affected by this 
proposed action. We listed Cyclic Crude and Intermediate Production, 
Industrial Inorganic Chemical Manufacturing, Industrial Organic 
Chemical Manufacturing, Plastic Materials and Resins Manufacturing, and 
Synthetic Rubber Manufacturing as area source categories under CAA 
section 112(c)(3) as part of the 1999 Integrated Urban Air Toxics 
Strategy (64 FR 38721, July 19, 1999). On June 26, 2002, we amended the 
area source category list by adding source categories, including 
Agricultural Chemicals and Pesticides Manufacturing, Miscellaneous 
Organic Chemical Manufacturing, and Pharmaceutical Production (67 FR 
43112, 43113). On November 22, 2002, we added Inorganic Pigments 
Manufacturing to the area source category list (67 FR 70427, 70428). In 
this action, we are proposing to amend the area source category list by 
adding Chemical Manufacturing with Ethylene Oxide (see section II.A.1 
of this preamble). The other nine CMAS categories are discussed further 
in section II.B of this preamble.

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

    In addition to being available in the docket, an electronic copy of 
this action is available on the internet. In accordance with 5 U.S.C. 
553(b)(4), a summary of this rulemaking may be found at https://www.regulations.gov/, Docket ID No. EPA-HQ-OAR-2024-0303. Following 
signature by the EPA Administrator, the EPA will post a copy of this 
proposed action at https://www.epa.gov/stationary-sources-air-pollution/chemical-manufacturing-area-sources-national-emission-standards. Following publication in the Federal Register, the EPA will 
post the Federal Register version of the proposal and key technical 
documents at this same website.
    A memorandum showing the edits that would be necessary to 
incorporate the changes to the CMAS NESHAP (40 CFR part 63, subpart 
VVVVVV) proposed in this action is available in the docket (Docket ID 
No. EPA-HQ-OAR-2024-0303). Following signature by the EPA 
Administrator, the EPA also will post a copy of this document to 
https://www.epa.gov/stationary-sources-air-pollution/chemical-
manufacturing-

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area-sources-national-emission-standards.

II. Background

A. What is the statutory authority for this action?

    The statutory authority for this action is provided by sections 112 
and 301 of the CAA, as amended (42 U.S.C. 7401 et seq.). Several CAA 
sections are relevant to this action as they specifically address 
regulations of HAP emissions from area sources. Collectively, CAA 
sections 112(c)(3), (d)(5), and (k)(3) are the basis of the Area Source 
Program under the Urban Air Toxics Strategy, which provides the 
framework for regulation of area sources under CAA section 112. Section 
112(k)(3)(B) of the CAA requires the EPA to identify at least 30 HAP 
that pose the greatest potential health threat in urban areas with a 
primary goal of achieving a 75 percent reduction in cancer incidence 
attributable to HAP emitted from stationary sources. As discussed in 
the Integrated Urban Air Toxics Strategy (64 FR 38706, 38715, July 19, 
1999), the EPA identified 30 HAP emitted from area sources that pose 
the greatest potential health threat in urban areas, and these HAP are 
commonly referred to as the ``30 urban HAP.'' CAA section 112(c)(3), in 
turn, requires the EPA to list sufficient categories or subcategories 
of area sources to ensure that area sources representing 90 percent of 
the emissions of the 30 urban HAP are subject to regulation. The EPA 
implemented these requirements through the Integrated Urban Air Toxics 
Strategy by identifying and setting standards for categories of area 
sources including the original nine CMAS categories that are addressed 
in this action. This proposed action presents the required CAA 
112(d)(6) technology review of the generally available control 
technology (GACT) standards that the EPA established in 2009 \1\ for 
the nine CMAS categories. In this action, we are also proposing to set 
additional GACT standards for these categories. In addition to the 
source categories and subcategories listed pursuant to CAA section 
112(c)(3), CAA section 112(c)(5) provides the EPA discretion to 
establish additional categories and subcategories of sources for 
regulation if a threat of adverse effects to human health or the 
environment is identified, per the criteria set forth in CAA section 
112(c)(1) and (3). Pursuant to CAA section 112(c)(5), and consistent 
with the requirements of CAA section 112(c)(3), this action also 
proposes for regulation as part of the CMAS NESHAP a new area source 
category, Chemical Manufacturing with Ethylene Oxide, and proposes GACT 
standards for that new source category pursuant to CAA section 
112(d)(5). Information about establishing a new area source category 
for regulation pursuant to CAA section 112(c)(3) and (5), setting GACT 
standards under CAA section 112(d)(5), and reviewing standards under 
CAA section 112(d)(6) are provided in sections II.A.1, II.A.2, and 
II.A.3 of this preamble, respectively.
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    \1\ See 74 FR 56008, October 29, 2009.
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1. Listing An Additional Category Under CAA Section 112(c)(5)
    CAA section 112(c)(5) provides that ``the Administrator may at any 
time list additional categories and subcategories of sources of 
hazardous air pollutants according to the same criteria for listing 
applicable under [CAA section 112(c)(1) and (3)].'' CAA 112(c)(3), in 
turn, provides in part that ``[t]he Administrator shall list . . . each 
category or subcategory of area sources which the Administrator finds 
presents a threat of adverse effects to human health or the environment 
(by such sources individually or in the aggregate) warranting 
regulation under this section.''
    In 2016, the EPA updated the integrated risk information system 
(IRIS) value for EtO to reflect new science related to the 
pollutant.\2\ The updated IRIS value indicates that EtO is far more 
carcinogenic than previously understood. In response to this update, 
the EPA Office of Inspector General (OIG) released a report in 2021 
using data from the 2014 National Air Toxics Assessment (NATA) 
identifying facilities that could present lifetime cancer risks to the 
public greater than or equal to 100-in-1 million.\3\ Several of these 
facilities were area source chemical manufacturers. Based on the 
revised carcinogenicity of EtO, the EPA decided to assess whether EtO 
emissions from CMAS should be listed as an area source category 
pursuant to CAA section 112(c)(3) and (5).
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    \2\ The review is available at https://iris.epa.gov/static/pdfs/1025tr.pdf.
    \3\ The report is available at https://www.epaoig.gov/sites/default/files/2021-05/documents/_epaoig_20210506-21-p-0129.pdf.
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    EtO is not one of the fifteen urban HAP currently regulated by the 
CMAS NESHAP. Therefore, to fully assess whether a source category 
including EtO emissions from area source chemical manufacturing 
operations presents an adverse effect to human health or the 
environment, facilities not currently part of the nine regulated source 
categories were considered. To that end, we conducted a risk assessment 
evaluating all reported HAP emissions from sources currently subject to 
the CMAS NESHAP as well as sources that we believe would become subject 
to the CMAS NESHAP if EtO were to be added to table 1 to 40 CFR part 
63, subpart VVVVVV. The results of the risk assessment are summarized 
in section II.E of this preamble. Based on the assessment, seven area 
source chemical manufacturing facilities were estimated to have maximum 
cancer risks greater than 100-in-1 million, all of which were driven 
primarily (greater than 90 percent) by EtO emissions.\4\ The maximum 
individual lifetime [cancer] risk (MIR) posed by the evaluated sources 
is 800-in-1 million, driven by EtO emissions from process vents (97 
percent).
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    \4\ For additional details on these facilities, please see the 
document titled Risk Assessment for the Chemical Manufacturing Area 
Source (CMAS) Categories in Support of the 2025 Technology Review 
for the Proposed Rule in the docket for this action.
---------------------------------------------------------------------------

    Given these estimates of risk, we propose that an area source 
category associated with EtO emissions from area source chemical 
manufacturers presents a threat of adverse effect on human health. 
Accordingly, consistent with CAA section 112(c)(3) and (5), we are 
proposing to list a new area source category. This area source 
category, Chemical Manufacturing with Ethylene Oxide, would encompass 
processes that produce a material or family of materials described by 
NAICS code 325 where EtO is used as a feedstock, generated as a 
byproduct, or is the material produced. This proposed source category 
matches the scope of the nine source categories currently regulated by 
the CMAS NESHAP, as described in section II.B of this preamble. Since 
the existing CMAS NESHAP currently regulates these nine area source 
categories collectively, we are proposing to also regulate the new 
Chemical Manufacturing with Ethylene Oxide area source category under 
the CMAS NESHAP at 40 CFR part 63, subpart VVVVVV. Alongside the 
listing of this new area source category, the EPA is proposing to add 
EtO specific applicability requirements at 40 CFR 63.11494(a)(2)(v) and 
to list EtO in table 1 to 40 CFR part 63, subpart VVVVVV.
    In conjunction with proposing to establish a new area source 
category for Chemical Manufacturing with Ethylene Oxide, the EPA must 
establish the level of control for the source category. Section II.A.2 
provides details on our authority to establish GACT standards pursuant 
to CAA section 112(d)(5) in lieu of maximum achievable control

[[Page 7946]]

technology (MACT) standards pursuant to CAA section 112(d)(2) and (3).
2. Alternative Standards for Area Sources Under CAA Section 112(d)(5)
    Under CAA section 112(d)(5), the EPA may elect to promulgate 
standards or requirements for area sources ``which provide for the use 
of generally available control technologies or management practices by 
such sources to reduce emissions of hazardous air pollutants.'' 
Additional information on GACT or management practices is found in the 
Senate report on the legislation (Senate report Number 101-228, 
December 20, 1989), which describes GACT as ``. . . methods, practices 
and techniques which are commercially available and appropriate for 
application by the sources in the category considering economic impacts 
and the technical capabilities of the firms to operate and maintain the 
emissions control systems.''
    Consistent with the legislative history, we can consider costs and 
economic impacts in determining GACT. Determining what constitutes GACT 
involves considering the control technologies and management practices 
that are generally available to the area sources in the source 
category. As previously mentioned, GACT standards were set for the CMAS 
categories in 2009. These GACT standards are discussed in section IV.C 
of this preamble. See section II.B of this preamble for details about 
each of the nine currently regulated CMAS categories.
    In this action, we are proposing to set additional GACT standards 
for the CMAS categories that would apply to certain emission sources 
(i.e., equipment leaks, heat exchange systems, process vents, storage 
tanks, wastewater, and transfer operations) associated with the 
proposed area source category, Chemical Manufacturing with Ethylene 
Oxide. In addition, we are proposing to set GACT standards for pressure 
vessels and PRDs. The proposed GACT standards are discussed in sections 
IV.A and IV.B of this preamble. In setting GACT, we always look to the 
standards applicable to major sources in the same industrial sector to 
determine if the control technologies and management practices are 
transferable and generally available to area sources. In appropriate 
circumstances, we may also consider technologies and practices at area 
and major sources in similar categories to determine whether such 
technologies and practices could be considered generally available for 
the area source category at issue. In this case, the control 
technologies and management practices for process units are 
transferable because process units at major source chemical 
manufacturing facilities are essentially no different than process 
units at area source chemical manufacturing facilities excepting that 
the former exceeds the major source HAP thresholds with respect to 
emissions and the latter does not. Finally, as we have already noted, 
in determining GACT for a particular area source category, we consider 
the costs and economic impacts of available control technologies and 
management practices on that category.
    GACT differs from MACT in that cost can be considered in the first 
instance when establishing a GACT standard. By contrast, when 
establishing MACT standards pursuant to CAA section 112(d)(3), the EPA 
must determine the average emission limitation achieved by the best 
performing 12 percent of existing sources (or average emission 
limitation achieved by the best performing 5 sources for existing 
sources with fewer than 30 sources) and the emission limitation 
achieved by the best controlled similar source for new sources, without 
regard to cost.
    As explained in greater detail in sections IV.A and IV.B of this 
preamble, we determined that the GACT standards we are proposing for 
sources emitting EtO (i.e., GACT standards for equipment leaks, heat 
exchange systems, process vents, storage tanks, wastewater, and 
transfer operations) located at CMAS, and the GACT standards we are 
proposing for pressure vessels and PRDs at these same area sources, 
should be similar, if not the same, as the major source standards that 
were finalized in the Miscellaneous Organic Chemical Manufacturing 
NESHAP (MON) and Hazardous Organic NESHAP (HON) pursuant to CAA section 
112(d)(6) and (f) (see 85 FR 49084, August 12, 2020 and 89 FR 42932, 
May 16, 2024, respectively). Our rationale for this is based on the 
similarities between production processes, emission points, emissions, 
and control technologies that are characteristic of both major and area 
source chemical manufacturing facilities and considerations of cost.\5\
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    \5\ The EPA also considers the costs and economic impacts of 
available control technologies and management practices when 
determining whether to revise a standard pursuant to section 
112(d)(6); and the EPA also considers costs, energy, and other 
relevant factors when determining whether to revise a standard in 
the second step of the ample margin of safety analysis pursuant to 
CAA section 112(f)(2)(A).
---------------------------------------------------------------------------

    We note that if standards for EtO are finalized, the EPA has 
committed to the Office of the Inspector General (OIG) to assess the 
risk posed from EtO emission sources subject to the CMAS NESHAP. 
Specifically, the EPA committed to assess risk within four years of 
promulgation of standards. At that time, the EPA would determine if it 
is appropriate to review the standards prior to the date required by 
CAA section 112(d)(6) (i.e., 8 years).\6\
---------------------------------------------------------------------------

    \6\ On June 1, 2022, the EPA, in response to the OIG's report 
stating that EPA should revise the CMAS NESHAP to regulate EtO and 
conduct a residual risk review, stated: ``. . . technology-based 
standards for EtO have not yet been established for the CMAS source 
category. Therefore, we plan to first evaluate EtO emissions from 
the source category, and if EtO emissions present a public health 
concern (i.e., by considering risk information), we will regulate 
EtO in the CMAS rule . . . However, within four years of 
promulgation (enough time to understand the level of emissions 
remaining after implementation of new standards) of an any initial 
EtO standards for CMAS, EPA would assess the risks from EtO 
emissions from CMAS sources to inform us on whether an earlier 
review date is appropriate.'' Refer to https://www.epaoig.gov/sites/default/files/documents/2022-06/_epaoig_21-P-0129_Agency_Response2.pdf for additional details.
---------------------------------------------------------------------------

3. Technology Review Under CAA Section 112(d)(6)
    CAA section 112(d)(6) requires the EPA to review standards 
promulgated under CAA section 112(d) and revise them ``as necessary 
(taking into account developments in practices, processes, and control 
technologies)'' no less often than every 8 years following promulgation 
of those standards. This is referred to as a ``technology review'' and 
is required for all standards established under CAA section 112(d) 
including GACT standards that apply to area sources.
    As previously mentioned, GACT standards were set for the CMAS 
categories in 2009. Although in this action we are proposing additional 
GACT standards for these categories, this proposed action also presents 
the required CAA 112(d)(6) technology review of the 2009 GACT standards 
for these source categories.

B. What are the source categories and how does the current NESHAP 
regulate HAP emissions?

    The EPA promulgated the CMAS NESHAP on October 29, 2009 (74 FR 
56008), and codified the NESHAP at 40 CFR part 63, subpart VVVVVV. As 
promulgated in 2009, and further amended on December 21, 2012 (77 FR 
75740), the CMAS NESHAP regulates HAP emissions from chemical 
manufacturing process units at an area source of HAP emissions if HAP 
listed in table 1 to 40 CFR part 63, subpart VVVVVV are present in the 
CMPU. A CMPU includes all process vessels, equipment, and activities 
necessary to

[[Page 7947]]

operate a chemical manufacturing process that produces a material or a 
family of materials described by NAICS code 325.\7\ A CMPU consists of 
one or more unit operations and any associated recovery devices. A CMPU 
also includes each storage tank, transfer operation, surge control 
vessel, and bottoms receiver associated with the production of such 
NAICS code 325 materials. The affected source is the facility-wide 
collection of CMPUs and each heat exchange system and wastewater system 
associated with a CMPU.
---------------------------------------------------------------------------

    \7\ Except for: (1) processes classified in NAICS Code 325222, 
325314, 325413, or 325998; (2) processes subject to standards for 
other listed area source categories in NAICS 325; (3) certain 
fabricating operations; (4) manufacture of photographic film, paper, 
and plate where material is coated or contains chemicals (but the 
manufacture of the photographic chemicals is regulated); and (5) 
manufacture of radioactive elements or isotopes, radium chloride, 
radium luminous compounds, strontium, and uranium.
---------------------------------------------------------------------------

    The CMAS NESHAP currently applies to chemical manufacturing 
operations at nine area source categories: (1) Agricultural Chemicals 
and Pesticides Manufacturing; (2) Cyclic Crude and Intermediate 
Production; (3) Industrial Inorganic Chemical Manufacturing; (4) 
Industrial Organic Chemical Manufacturing; (5) Inorganic Pigments 
Manufacturing; (6) Miscellaneous Organic Chemical Manufacturing; (7) 
Plastic Materials and Resins Manufacturing; (8) Pharmaceutical 
Production; and (9) Synthetic Rubber Manufacturing. These nine CMAS 
categories encompass facilities that use as feedstocks,\8\ generate as 
byproducts, or produce as products any of the following 15 HAP: 1,3-
butadiene; 1,3-dichloropropene; acetaldehyde; chloroform; ethylene 
dichloride; hexachlorobenzene; methylene chloride; quinoline (these 
eight HAP are referred to as the ``Table 1 \9\ organic HAP''); 
compounds of arsenic, cadmium, chromium, lead, manganese, or nickel 
(these six HAP are referred to as the ``Table 1 metal HAP''); or 
hydrazine. In this preamble we refer to the nine source categories 
collectively as CMAS categories (we are also proposing a tenth source 
category as discussed in section II.A.1 of this preamble). Descriptions 
of the nine source categories are as follows:
---------------------------------------------------------------------------

    \8\ Feedstocks are reactants, solvents, or any other additives 
to the process.
    \9\ ``Table 1'' refers to table 1 to 40 CFR part 63, subpart 
VVVVVV.
---------------------------------------------------------------------------

    Agricultural Chemicals and Pesticides Manufacturing. The 
agricultural chemicals and pesticides manufacturing source category is 
designated by NAICS codes 325311 (nitrogenous fertilizer 
manufacturing), 325312 (phosphatic fertilizer manufacturing), and 
325320 (pesticide and other agricultural chemical manufacturing). 
Products of this industry include nitrogenous and phosphatic fertilizer 
materials including anhydrous ammonia, nitric acid, ammonium nitrate, 
ammonium sulfate, urea, phosphoric acid, superphosphates, ammonium 
phosphates, and calcium metaphosphates. The source category also 
includes the formulation and preparation of ready-to-use agricultural 
and household pest control chemicals from technical chemicals or 
concentrates, the production of concentrates which require further 
processing before use as agricultural pesticides, and the manufacturing 
or formulating of other agricultural chemicals such as minor or trace 
elements and soil conditioners.
    Organic Chemical Production. The cyclic crude and intermediate 
production, industrial organic chemical manufacturing, and 
miscellaneous organic chemical manufacturing source categories are 
discussed collectively because there is considerable overlap in the 
NAICS codes that apply to these source categories. These source 
categories include cellulosic organic fiber manufacturing as well as 
other source categories that are designated by NAICS codes 32511 
(petrochemical manufacturing), 325130 (synthetic dye and pigment 
manufacturing), 32519 (other basic organic chemical manufacturing), and 
3256 (soap, cleaning compound, and toilet preparation manufacturing). 
The source category also includes organic gases designated by NAICS 
code 325120 (industrial gas manufacturing), and it includes production 
of chemicals such as explosives and photographic chemicals designated 
by NAICS code 3259 (other chemical product and preparation 
manufacturing). Raw materials for this industry include, for example, 
refined petroleum chemicals, coal tars, and wood. The industry 
manufactures a wide variety of final products as well as numerous 
chemicals that are used as feedstocks to produce these final products 
and products in other chemical manufacturing source categories. 
Examples of types of products include solvents, organic dyes and 
pigments, plasticizers, alcohols, detergents, and flavorings.
    Industrial Inorganic Chemical Manufacturing. The industrial 
inorganic chemical manufacturing source category includes manufacturing 
of inorganic gases that are designated by NAICS code 325120 (industrial 
gas manufacturing), manufacturing of inorganic dyes that are designated 
by NAICS code 325130 (synthetic dye and pigment manufacturing), and 
most manufacturing designated by NAICS code 32518 (other basic 
inorganic chemical manufacturing). Exceptions to production designated 
by NAICS code 32518 include carbon black and mercury cell chlor-alkali 
production, which are separate source categories.
    Inorganic Pigment Manufacturing. Inorganic pigments are part of 
NAICS code 325130 (synthetic dye and pigment manufacturing). The 
majority of inorganic pigments are oxides, sulfides, oxide hydroxides, 
silicates, sulfates, or carbonates that normally consist of single 
component particles. The inorganic pigment manufacturing processes can 
generally be divided between those that use partial combustion and 
those that use pure pyrolysis. Inorganic pigments generally are used to 
impart colors to a variety of compounds. They may also impart 
properties of rust inhibition, rigidity, and abrasion resistance. 
Inorganic pigments are generally insoluble and remain unchanged 
physically and chemically when mixed with a carrier. Pigment 
manufacturers supply inorganic colors in a variety of forms including 
powders, pastes, granules, slurries, and suspensions. Pigments are used 
in the manufacture of paints and stains, printing inks, plastics, 
synthetic textiles, paper, cosmetics, contact lenses, soaps, 
detergents, wax, modeling clay, chalks, crayons, artists' colors, 
concrete, masonry products, and ceramics.
    Pharmaceutical Production. The pharmaceutical manufacturing source 
category consists of chemical production operations that produce drugs 
and medication. These operations include chemical synthesis (deriving a 
drug's active ingredient) and chemical formulation (producing a drug in 
its final form). The source category is designated by NAICS codes 
325411 (medicinal and botanical manufacturing), 325412 (pharmaceutical 
preparation manufacturing), and 325414 (biological product, except 
diagnostic, manufacturing).
    Plastic Materials and Resins Manufacturing. This source category is 
designated by NAICS code 325211 (plastics material and resin 
manufacturing). Examples of products in this source category include 
epoxy resins, nylon resins, phenolic resins, polyesters, polyethylene 
resins, and styrene resins. The source category does not include 
polyvinyl chloride and copolymers production, which is a separate 
source category.
    Synthetic Rubber Manufacturing. The synthetic rubber manufacturing 
source category is designated by NAICS code

[[Page 7948]]

325212 (synthetic rubber manufacturing). Facilities in this source 
category manufacture synthetic rubber or vulcanizable elastomers by 
polymerization or copolymerization. For this source category, an 
elastomer is defined as a rubber-like material capable of 
vulcanization, such as copolymers of butadiene and styrene, copolymers 
of butadiene and acrylonitrile, polybutadienes, chloroprene rubbers, 
and isobutylene-isoprene copolymers.
    The HAP emission sources at facilities subject to the CMAS NESHAP 
include process vents, storage tanks, equipment leaks, transfer 
operations, and wastewater. Additionally, some facilities have cooling 
towers or other heat exchangers. The GACT standards for CMAS include 
emission standards in the form of management practices for each CMPU as 
well as emission limits for certain emission sources including process 
vents and storage tanks. The rule also establishes management practices 
and other emission reduction requirements for wastewater systems and 
heat exchange systems.
    As of May 1, 2024, the EPA identified 251 facilities in operation 
that are subject to the CMAS NESHAP. In addition, we are aware of 29 
more facilities that would become subject to the CMAS NESHAP if EtO 
were to be added to table 1 to the CMAS NESHAP, as proposed (see 
section II.A.1 of this preamble) \10\. In this preamble, we referred to 
all 280 of these facilities collectively as ``CMAS facilities.'' The 
list of CMAS facilities located in the United States that are part of 
the CMAS categories with processes subject to the CMAS NESHAP is 
presented in the document titled List of Facilities Subject to the CMAS 
NESHAP, which is available in the docket for this rulemaking.
---------------------------------------------------------------------------

    \10\ While 29 facilities were identified to become subject to 
CMAS NESHAP if EtO were to be added to table 1 to 40 CFR part 63, 
subpart VVVVVV, four of the 251 facilities currently subject to the 
CMAS NESHAP also emit EtO. As such, in total, there are 33 
facilities emitting EtO that may be impacted by this action.
---------------------------------------------------------------------------

C. What data collection activities were conducted to support this 
action?

1. Facility List
    The EPA used several data sources to determine the facilities that 
are subject to the CMAS NESHAP discussed in section II.B of this 
preamble. We began with the facility list from the original rulemaking 
for the CMAS NESHAP (74 FR 56008, October 29, 2009). This list was 
supplemented with information from the Office of Enforcement and 
Compliance Assurance's Enforcement and Compliance History Online tool 
(https://echo.epa.gov) as well as other facility lists from the EPA's 
recent chemical sector rulemakings (e.g., HON, MON, Organic Liquid 
Distribution NESHAP (OLD), Ethylene Production MACT standards (EMACT 
standards), and Polyether Polyols Production (PEPO) NESHAP).
    We also collected and considered facility specific information from 
the regions and/or states, if the information had not already been 
captured by the previous steps. For example, we obtained title V air 
permits from publicly available online state databases (where 
available). In cases where an online database was incomplete or did not 
exist, the EPA contacted the region and/or state for help in obtaining 
the air permits or determining whether a facility was subject to the 
CMAS NESHAP or may become subject to the CMAS NESHAP if EtO were to be 
added to table 1 to 40 CFR part 63, subpart VVVVVV. The EPA also 
conducted internet searches to determine the status of the facility 
(e.g., whether the facility was still open, permanently closed, and/or 
sold). Additional details about how the facility list was developed are 
provided in the document titled List of Facilities Subject to the CMAS 
NESHAP, which is available in the docket for this rulemaking.
    The EPA solicits comment on the assumptions used to estimate the 
number of facilities anticipated to be impacted by this action.
2. Emissions Inventory
    For each facility subject to the CMAS NESHAP, we gathered emissions 
data from the most recent version of the 2017 National Emissions 
Inventory (NEI), published in January 2021. Apart from the 2020 NEI 
(which was the first year of the COVID-19 pandemic), the 2017 NEI was 
the most vetted and recent publicly available data set at the time EPA 
began gathering information for this proposed rulemaking.\11\
---------------------------------------------------------------------------

    \11\ Refer to the 2017 NEI Technical Support Document for 
detailed discussion on the types of review and augmentation 
performed for 2017 NEI (https://www.epa.gov/sites/default/files/2021-02/documents/nei2017_tsd_full_jan2021.pdf).
---------------------------------------------------------------------------

    We consulted with state agencies, EPA regions, air permits, and 
facilities to determine whether any EtO records in the CMAS emissions 
inventory needed to be updated (beyond the 2017 NEI).\12\ This review 
revealed that several facilities have either voluntarily implemented 
EtO emission reduction measures since 2017 or implemented them due to 
state or other requirements; therefore, we made amendments to these EtO 
records to reflect the specific reduction measures. See appendix 1 of 
the document titled Risk Assessment for the Chemical Manufacturing Area 
Source (CMAS) Source Categories in Support of the 2025 Technology 
Review for the Proposed Rule, which is available in the docket for this 
rulemaking, for additional details on the analysis and methodology used 
to develop the CMAS emissions inventory.
---------------------------------------------------------------------------

    \12\ For facilities that would become subject (or are already 
subject) to the CMAS NESHAP if EtO were to be added to table 1 to 40 
CFR part 63, subpart VVVVVV, as proposed.
---------------------------------------------------------------------------

3. Other Data Collection Activities
    To inform our reviews of the Agency's emission standards, we 
reviewed the EPA's Reasonably Available Control Technology (RACT)/Best 
Available Control Technology (BACT)/Lowest Achievable Emission Rate 
(LAER) Clearinghouse and regulatory development efforts for similar 
sources published after the CMAS NESHAP was developed.
    In January 2022, the EPA issued requests, pursuant to CAA section 
114, to collect information from HON facilities (nine being also 
subject to the PEPO NESHAP) owned and operated by eight entities (i.e., 
corporations). This effort focused on gathering comprehensive 
information about process equipment, control technologies, point and 
fugitive emissions, and other aspects of facility operations. 
Additionally, the EPA requested stack testing for certain emission 
sources (e.g., pollutants, including EtO, for vent streams). Also, the 
EPA required that facilities conduct fugitive emission testing (i.e., 
fenceline monitoring) for any of six specific HAP they emit: benzene; 
1,3-butadiene; chloroprene; EtO; ethylene dichloride; and vinyl 
chloride. Companies submitted responses (and follow-up responses) and 
testing results to the EPA during the summer and fall of 2022. Given 
that CMPU sources subject to the CMAS NESHAP can be similar to HON CMPU 
sources and PEPO sources,\13\ the EPA used the collected information to 
estimate environmental and cost impacts associated with some of the 
regulatory options considered and reflected in this proposed action. 
The information not claimed as CBI by respondents is provided in the 
document titled Data Received from Information Collection Request for

[[Page 7949]]

Chemical Manufacturers, which is available in the docket for this 
rulemaking.
---------------------------------------------------------------------------

    \13\ HON CMPUs and polyether polyol manufacturing process units 
(PMPUs) associated with the PEPO NESHAP have similar processes as 
CMAS CMPUs in that regardless of size, each of these process units 
may include chemical manufacturing equipment, heat exchange systems, 
process vents, storage tanks, transfer operations, and/or 
wastewater.
---------------------------------------------------------------------------

D. What other relevant background information and data are available?

    In proposing these amendments, we relied on certain technical 
reports and memoranda that the EPA developed for flares used as air 
pollution control devices (APCDs) in the Petroleum Refinery Sector risk 
and technology review (RTR) and new source performance standards (NSPS) 
rulemaking (80 FR 75178, December 1, 2015). The Petroleum Refinery 
Sector rulemaking docket is at Docket ID No. EPA-HQ-OAR-2010-0682. For 
completeness of the rulemaking record for this action and for ease of 
reference in finding these items in the publicly available Petroleum 
Refinery Sector rulemaking docket, we are including the most relevant 
flare-related technical support documents in the docket for this 
proposed action (Docket ID No. EPA-HQ-OAR-2024-0303) and including a 
list of all documents used to inform the 2015 flare provisions in the 
Petroleum Refinery Sector RTR and NSPS rulemaking in the document 
titled Clean Air Act Section 112(d)(5) GACT Standard Analysis for 
Flares that Emit Ethylene Oxide and Section 112(d)(6) Technology Review 
for Flares Associated with Chemical Manufacturing Process Units at Area 
Sources Subject to the CMAS NESHAP, which is available in the docket 
for this rulemaking.
    We are also relying on data gathered to support the rulemakings for 
the EMACT standards, HON, and MON, as well as memoranda documenting the 
technology reviews for those processes. Many of the emission sources 
for ethylene production facilities, HON facilities, and MON facilities 
are similar to CMAS facilities, and the EPA analyzed several of the 
control options for the CMAS NESHAP that the Agency also analyzed for 
the rulemakings for the EMACT standards, HON, and MON. The memoranda 
and background technical information can be found in the Ethylene 
Production RTR rulemaking docket (Docket ID No. EPA-HQ-OAR-2017-0357), 
the HON rulemaking docket (Docket ID No. EPA-HQ-OAR-2022-0730), and the 
MON RTR rulemaking docket (Docket ID No. EPA-HQ-OAR-2018-0746). 
Additional information related to the promulgation and subsequent 
amendments of the CMAS NESHAP is available in Docket ID No. EPA-HQ-OAR-
2008-0334.

E. What are the results of the EPA's risk assessment?

    As discussed in section II.A.1, the EPA conducted a human health 
risk assessment to determine if EtO emissions from CMAS present a 
threat of adverse effects to human health (e.g., a public health 
concern) and therefore warrant regulation via the creation of a new 
source category pursuant to CAA section 112(c)(3) and (5). Following 
the update to the IRIS value for EtO, it became apparent that emissions 
of EtO from CMAS could be posing a significant threat to public health. 
The OIG released a report in 2021 that identified potential elevated 
cancer risks due to EtO emissions from CMAS using data from the 2014 
NATA.\14\ While the primary focus of the risk assessment was on EtO 
emissions, consistent with other risk assessments for HAPs, we 
estimated the MIR posed by emissions of HAP that are carcinogens from 
each evaluated CMAS, the hazard index (HI) for chronic exposures to HAP 
with the potential to cause noncancer health effects, and the hazard 
quotient (HQ) for acute exposures to HAP with the potential to cause 
noncancer health effects.\15\ This section summarizes the results of 
those analyses.
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    \14\ The report is available at https://www.epaoig.gov/sites/default/files/2021-05/documents/_epaoig_20210506-21-p-0129.pdf.
    \15\ The MIR is defined as the cancer risk associated with a 
lifetime of exposure at the highest concentration of HAP where 
people are likely to live. The HQ is the ratio of the potential HAP 
exposure concentration to the noncancer dose-response value; the HI 
is the sum of HQs for HAP.
---------------------------------------------------------------------------

    The EPA often conducts risk assessments at both the facility and 
source category level when investigating human health concerns and uses 
standard methodology for all risk assessments. However, we note that 
this risk assessment was completed using the emissions inventory 
described in section II.C.2 of this preamble. As such, there are 
uncertainties with the results of the risk assessment engendered by the 
uncertainties associated with the emissions inventory. However, given 
the information available, we believe the risk assessment supports our 
conclusion that these sources present a threat of an adverse impact on 
human health. Additional details on the risk assessment and exact 
methodology are presented in the document titled, Risk Assessment for 
the Chemical Manufacturing Area Source (CMAS) Source Categories in 
Support of the 2025 Technology Review for the Proposed Rule, which is 
available in the docket for this rulemaking.
    As discussed in section II.A.1 of this preamble, the MIR posed by 
the evaluated sources is 800-in-1 million, driven primarily (greater 
than 90 percent) by EtO emissions from process vents (97 percent). 
Approximately 4.4 million people within 50 kilometers (km) of the 
evaluated CMAS are estimated to have cancer risks above 1-in-1 million 
and 3,600 people are estimated to have cancer risks above 100-in-1 
million due to emissions from the sources. The people with risks above 
100-in-1 million all reside within 10 km of the sources. The sources 
are estimated to result in 0.4 additional cancer cases per year, or 1 
cancer case every 2.5 years. Emissions from the evaluated CMAS drive 
cancer risk attributable to whole facility emissions, such that the 
risk posed by all HAP emissions from the facilities are generally the 
same as the risk posed by the evaluated sources, except that emissions 
from whole facility emissions increase the population with risk greater 
than 1-in-1 million living within 50 km by 200,000 people.
    The maximum chronic noncancer target organ-specific hazard index 
(TOSHI) for the evaluated CMAS is estimated to be 3 (for respiratory 
and immunological effects) at two facilities due to nickel compounds 
emissions from process vents at one facility and equipment leaks and 
fugitive emissions at the other facility. The same nickel emissions 
also drive the estimated maximum facility-wide TOSHI of 3. 
Approximately 1,500 people are estimated to have a TOSHI greater than 1 
due to emissions from the evaluated CMAS.
    The estimated reasonable worst-case off-site acute inhalation 
exposures to emissions from the CMAS categories results in an estimated 
maximum modeled acute noncancer HQ of 20 based on CalEPA's Chronic 
Reference Exposure Level for acrolein. It is important to note that 
when assessing acute inhalation exposures, the EPA makes conservative 
assumptions about emission rates, meteorology, and exposure location. 
We assume that an individual is present at the location of maximum 
exposure at the exact same hour that peak emissions occur (using a 
default factor of 10 from average actual annual emissions rates) and 
the exact same hour the reasonable worst-case air dispersion conditions 
(i.e., 99th percentile) occur. Together, these assumptions represent a 
reasonable worst-case actual exposure scenario. In most cases, it is 
unlikely that a person would be located at the point of maximum 
exposure during the time when peak emissions and reasonable

[[Page 7950]]

worst-case air dispersion conditions occur simultaneously. Furthermore, 
at the facility where the maximum HQ of 20 is estimated, the maximum 
exposure is modeled to occur along the fenceline of the facility at a 
location immediately surrounded by farmland making it more unlikely a 
person would be located at that point at the exact hour the peak 
emissions and the reasonable worst-case air dispersion conditions 
occur.
    We also conducted a community-based risk assessment for facilities 
currently subject to the CMAS NESHAP or who would become subject to the 
CMAS NESHAP with the proposal of the new area source category (see 
section II.C.1 of this preamble for details on how the facility list 
was developed). The goal of this assessment was to estimate cancer risk 
from HAP emitted from all local stationary point sources for which we 
have emissions data. We estimated the overall inhalation cancer risk 
due to emissions from all stationary point sources impacting census 
blocks within 10 km of the CMAS facilities. Specifically, we combined 
the modeled impacts from category and non-category HAP sources at CMAS 
facilities, as well as other stationary point source HAP emissions. The 
results indicate that the community-level maximum individual cancer 
risk is 5,000-in-1 million, with all risk attributable to chromium VI 
emissions from an area source iron foundry. The Agency will investigate 
these emissions to determine if follow-up action is necessary. We note 
that the 2020 NEI data (the baseline for the community-level 
assessment) for the facility driving the community-level MIR present an 
anomalously high year of chromium VI emissions compared to other years. 
Also, the default speciation of chromium emissions to chromium III and 
chromium VI emissions done by the NEI is a conservative estimate of 
emissions and may not be representative of the actual emissions. In 
addition, we note that there is additional uncertainty in non-CMAS 
categories emissions because they were not reviewed to the same extent 
as emissions from CMAS facilities. Within 10 km, the population exposed 
to cancer risks greater than 100-in-1 million from all nearby emissions 
is approximately 5,600. For comparison, approximately 3,600 people have 
cancer risks greater than 100-in-1 million due to emissions from the 
evaluated CMAS NESHAP (see table 1 of this preamble).
    After the controls proposed in this action are implemented for the 
CMAS categories (see sections IV.A through IV.C of this preamble), 
including the contribution from all non-EtO HAP, the maximum individual 
cancer risk is estimated to be 100-in-1 million and no facilities are 
estimated to pose cancer risk greater than 100-in-1 million. The number 
of people living within 50 km of CMAS facilities with risk greater than 
1-in-1 million due to emissions from the CMAS categories will decrease 
from 4.4 million to 2.3 million. Chronic and acute noncancer risk is 
not estimated to change, although our proposal to remove the 50 parts 
per million by volume (ppmv) criteria as part of the definition of 
``metal HAP process vent'' (see section IV.C.3 of this preamble) is 
anticipated to reduce emissions of nickel that drive the chronic 
noncancer risk. After implementation of the proposed controls, the 
community-level maximum individual cancer risk will remain unchanged at 
5,000-in-1 million. The population (within 10 km of CMAS facilities) 
exposed to cancer risks greater than 100-in-1 million from all nearby 
emissions will be reduced from 5,600 people to 1,900 people; a 66 
percent reduction from the baseline. The increased cancer risk for most 
of these 1,900 people is driven largely by emissions of chromium VI 
from non-CMAS facilities within 10 km of CMAS facilities.
    See table 1 of this preamble for a summary of the CMAS NESHAP 
inhalation risk assessment results. We present the full results and 
methods of the risk assessment in more detail, in the document titled 
Risk Assessment for the Chemical Manufacturing Area Source (CMAS) 
Source Categories in Support of the 2025 Technology Review for the 
Proposed Rule, which is available in the docket for this rulemaking.

                     Table 1--Inhalation Cancer Risk Assessment Results for Communities Living Within 10 to 50 km of CMAS Facilities
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                 Maximum     Estimated population at increased risk                                            Refined
                                                individual                 of cancer                                                           maximum
                                   Number of   cancer risk -----------------------------------------  Estimated annual     Maximum chronic    screening
         Risk assessment           facilities     (-in-1                                              cancer incidence     noncancer TOSHI      acute
                                      \1\        million)    >100-in-1 million    >=1-in-1 million    (cases per year)                        noncancer
                                                   \2\                                                                                            HQ
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                       Baseline (Pre-Control) Actual Emissions \3\
--------------------------------------------------------------------------------------------------------------------------------------------------------
Source Category.................          248          800  3,600 (10 km)......  2 million (10 km).  0.2 (10 km).......  3 (respiratory,              20
                                                            3,600 (50 km)......  4.4 million (50     0.4 (50 km).......   immunological).
                                                                                  km).
Facility-wide...................          279          800  3,600 (10 km)......  2.2 million (10     0.2 (10 km).......  3 (respiratory,          \4\ --
                                                            3,600 (50 km)......   km).               0.4 (50 km).......   immunological).
                                                                                 4.6 million (50
                                                                                  km).
Community-based.................    \5\ 9,932        5,000  5,600 (10 km)......  8.6 million (10     0.8 (10 km).......  ..................  ...........
                                                                                  km).
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                 Post-Control Emissions
--------------------------------------------------------------------------------------------------------------------------------------------------------
Source Category.................          248          100  0..................  1.3 million (10     0.1 (10 km).......  3 (respiratory,              20
                                                                                  km).               0.2 (50 km).......   immunological).
                                                                                 2.3 million (50
                                                                                  km).
Facility-wide...................          279          100  0..................  1.4 million (10     0.1 (10 km).......  3 (respiratory,     ...........
                                                                                  km).               0.2 (50 km).......   immunological).
                                                                                 2.5 million (50
                                                                                  km).
Community-based.................    \3\ 9,932        5,000  1,900 (10 km)......  8 million (10 km).  0.6 (10 km).......  ..................  ...........
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Thirty-one (31) additional facilities were modeled for the CMAS whole-facility analysis compared to the CMAS categories analysis, because 279
  facilities were originally identified as potentially subject to the CMAS NESHAP considering the current and proposed source categories based on permit
  review and/or the facility's presence in the previous rulemaking's facility list. However, upon further review, only 248 of these 279 facilities were
  identified as having emissions from the CMAS categories.

[[Page 7951]]

 
\2\ Maximum individual excess lifetime cancer risk due to HAP emissions.
\3\ Potential differences between actual emission levels and the maximum emissions allowable under EPA's standards (i.e., ``allowable emissions'') were
  also evaluated for the CMAS categories. For the 248 CMAS facilities, there were 4 facilities with allowable emissions that differed from actual
  emissions. These emissions were evaluated and it was determined there would be no appreciable difference in the risk results; therefore, the risk
  results provided based on actual emissions also describe the risk assessment results based on allowable emissions.
\4\ ``--'' Indicates where an assessment was not conducted.
\5\ 9,653 nearby non-CMAS facilities in addition to the 279 facilities CMAS facilities evaluated.

III. Analytical Procedures and Decision-Making

A. How do we determine GACT?

    As provided in CAA section 112(d)(5), we are proposing standards 
representing GACT to regulate EtO emissions from equipment leaks, heat 
exchange systems, process vents, storage tanks, wastewater, and 
transfer operations located at CMAS. The statute does not set any 
condition precedent for issuing standards under CAA section 112(d)(5) 
other than that the area source category or subcategory at issue must 
be one that EPA listed pursuant to CAA section 112(c), which is the 
case here. In determining what constitutes GACT for this proposed rule, 
we considered the control technologies and management practices that 
are generally available to EtO emission sources at CMAS by examining 
relevant data and information, including information collected from the 
Synthetic Organic Chemical Manufacturing Industry (SOCMI) and PEPO 
Production major source categories. We also considered the standards 
for major chemical manufacturing sources subject to the MON and HON 
(see 85 FR 49084, August 12, 2020, and 89 FR 42932, May 16, 2024, 
respectively) to determine if the control technologies and work 
practice standards for the major sources are generally available to 
area sources as well. Finally, we considered the costs of available 
control technologies and management practices on area sources.
    From the information that we have collected to date in conjunction 
with this rulemaking, which includes information about process 
equipment, control technologies, point and fugitive emissions, and 
other aspects of facility operations at major chemical manufacturing 
sources, we know that area sources have the same types of emissions, 
emission sources, and controls as major sources. Equipment leaks, heat 
exchange systems, process vents, storage tanks, wastewater, and 
transfer operations at major and area sources are using the same 
control technologies. There are generally no discernible differences 
between the processes at area and major chemical manufacturing sources 
excepting size. In fact, major and area sources use similar, if not 
identical, control technologies and practices to manage process 
emissions. Therefore, the control technologies used by chemical 
manufacturing major sources are generally available for CMAS.

B. How do we perform the technology review?

    For the NESHAP area source GACT standard, our technology review 
primarily focuses on the identification and evaluation of developments 
in practices, processes, and control technologies that have occurred 
since the standards were promulgated. Where we identify such 
developments, we analyze their technical feasibility, estimated costs, 
energy implications, and non-air environmental impacts. We also 
consider the emission reductions associated with applying each 
development. This analysis informs our decision of whether it is 
``necessary'' to revise the emissions standards. In addition, we 
consider the appropriateness of applying controls to new sources versus 
retrofitting existing sources. For this exercise, we consider any of 
the following to be a ``development'':
     Any add-on control technology or other equipment that was 
not identified and considered during development of the original GACT 
standards;
     Any improvements in add-on control technology or other 
equipment (that were identified and considered during development of 
the original GACT standards) that could result in additional emissions 
reduction;
     Any work practice, management practice, or operational 
procedure that was not identified or considered during development of 
the original GACT standards;
     Any process change or pollution prevention alternative 
that could be broadly applied to the industry and that was not 
identified or considered during development of the original GACT 
standards; and
     Any significant changes in the cost (including cost 
effectiveness) of applying controls (including controls the EPA 
considered during the development of the original GACT standards).
    In addition to reviewing the practices, processes, and control 
technologies that were considered at the time we originally developed 
(or last updated) the CMAS NESHAP, we review a variety of data sources 
in our investigation of potential practices, processes, or controls to 
consider. See sections II.C and II.D of this preamble for information 
on the specific data sources that were reviewed as part of the 
technology review.

IV. Analytical Results and Proposed Decisions

A. What are our proposed decisions regarding standards representing 
GACT for EtO emissions from CMAS, and what is the rationale for those 
decisions?

    As discussed in section II.A.1 of this preamble, the EPA is 
proposing, pursuant to CAA section 112(c)(3) and (5), to create an area 
source category describing chemical manufacturing operations using EtO. 
Specifically, we are proposing at 40 CFR 63.11494(a)(2)(v) that you are 
subject to the CMAS NESHAP if you own or operate a CMPU that is located 
at an area source of HAP and EtO is used as a feedstock at an 
individual concentration greater than 0.1 percent by weight; generated 
as a byproduct and is present in the CMPU in any liquid stream (process 
or waste) at a concentration of greater than or equal to 1 part per 
million by weight (ppmw); generated as a byproduct and is present in 
the CMPU in any continuous process vent or batch process vent at a 
concentration greater than 1 ppmv; or is produced as a product of the 
CMPU. The EPA is also proposing amendments to the CMAS NESHAP pursuant 
to CAA section 112(d)(5) to include:
     New monitoring requirements for leaks from equipment in 
EtO service;
     New monitoring requirements for leaks from heat exchange 
systems in EtO service;
     A new emissions standard for batch and continuous process 
vents in EtO service;
     A new emissions standard for storage tanks in EtO service;
     New control requirements for wastewater streams in EtO 
service;
     Improved operational and monitoring requirements for 
flares that emit EtO;
     A new fenceline monitoring standard related to EtO 
emissions; and
     A requirement that any release event from a PRD in EtO 
service is a deviation.
    The data, analyses, results, and proposed decisions pursuant to CAA 
section 112(d)(5) are presented for each

[[Page 7952]]

emission source in sections IV.A.1 through IV.A.8 of this preamble.
    The EPA considers multiple factors in assessing the costs of 
emission reductions.\16\ These factors include, but are not limited to, 
total capital costs, total annual costs, cost effectiveness, and annual 
costs compared to total annual revenues for ultimate owners of affected 
facilities (i.e., costs to sales ratios). EtO is a highly potent 
carcinogen and the cost-effectiveness numbers presented in sections 
IV.A.1 through IV.A.8 of this preamble are within range of values that 
we have determined to be cost effective for highly toxic HAP. For small 
hard chromium electroplating, to provide an ample margin of safety to 
protect public health, costs of $15,000 per pound (lb) ($30,000,000 per 
ton) were finalized due to the toxicity of hexavalent chromium (see 77 
FR 58227-8 and 77 FR 58239, September 19, 2012). EtO is similarly 
highly toxic. The cost-effectiveness values presented in sections 
IV.A.1 through IV.A.8 of this preamble are also within the range of 
cost-effectiveness for control of EtO emissions that the EPA found 
reasonable as part of the recent commercial sterilizers rulemaking (see 
89 FR 24090, April 5, 2024). In this rulemaking, the EPA accepted costs 
of up to $17,500,000/ton for existing sources in setting standards 
under CAA section 112(d)(5). In addition, our established methodology 
for assessing economic impacts of regulations indicates that the 
potential for adverse economic impacts begins when a costs to sales 
ratio exceeds three percent. According to our estimates, the 
anticipated annual costs of the proposed emission control options 
discussed below are well below three percent of annual sales for the 
majority of the owners of potentially impacted EtO sources.
---------------------------------------------------------------------------

    \16\ Natural Resources Defense Council v. EPA, 749 F.3d 1055, 
1060 (DC Circ. April 18, 2014) (``Section 112 does not command the 
EPA to use a particular form of cost analysis'').
---------------------------------------------------------------------------

1. Equipment Leaks in EtO Service
    Emissions from equipment leaks occur in the form of gases or 
liquids that escape to the atmosphere through connection points (e.g., 
threaded connectors) or through the moving parts of components such as 
pumps and valves. EtO emissions are released from equipment leaks when 
the components are associated with equipment that contain EtO (referred 
to as equipment in EtO service). We provide details about equipment 
leaks, including how the CMAS NESHAP regulates them, in our technology 
review discussion (see section IV.C.1 of this preamble). For the GACT 
standard analysis, we evaluated a single control option for leaks from 
equipment in EtO service. The control option evaluated is identical to 
the HON standards for leaks from equipment in EtO service and similar 
(in terms of the technology, which is using EPA Method 21 instrument 
monitoring) to the control options that we evaluated in the equipment 
leaks technology review (see section IV.C.1 of this preamble). The EPA 
recently added EtO-specific requirements into the HON for equipment in 
EtO service that requires a more stringent monitoring frequency (i.e., 
monthly monitoring) and lower leak definitions (i.e., 100 ppmv or 500 
ppmv) compared to monitoring for leaks from equipment not in EtO 
service. In the HON, equipment in EtO service is equipment that 
contains or contacts a fluid that is at least 0.1 percent by weight 
EtO.
    As such, given the transferability of major source work practice 
standards to CMAS management practices due to the minimal differences 
between performing instrument monitoring at a major source compared to 
an area source, we evaluated the following option to represent GACT for 
equipment ``in ethylene oxide service'' that are located at CMAS:
     Control Option 1 (if EtO was added to table 1 to 40 CFR 
part 63, subpart VVVVVV): conduct monthly EPA Method 21 monitoring at a 
leak definition of 100 ppmv for connectors and valves in EtO service 
and 500 ppmv for pumps in EtO service.
    We find this Control Option and the associated technologies to be 
``generally available'' per the language of CAA section 112(d)(5). 
While it was not proposed in the original CMAS rulemaking, an 
instrument monitoring program similar to the MON was evaluated as part 
of the original CMAS rulemaking in 2008. In addition, conducting EPA 
Method 21 monitoring has been an option for the CMAS management 
practices since promulgation (i.e., owners and operators may perform 
EPA Method 21 monitoring in lieu of conducting audio, visual, and 
olfactory (AVO) inspections). Also, the EPA is aware of facilities that 
have already implemented instrument monitoring in some capacity as part 
of complying with other regulatory requirements or as part of a 
company-wide initiative to address EtO emissions. Therefore, we 
conclude that instrument monitoring is generally available.
    We estimated the cost and emissions reductions of Control Option 1 
for 33 CMAS EtO facilities. Using background information available to 
the EPA (including air permits and information received from various 
EPA regional offices), it was determined that 10 CMAS EtO facilities 
are already conducting instrument monitoring as part of an LDAR program 
for their equipment in EtO service. Based on this, there are two types 
of facilities for purposes of identifying their baseline LDAR program 
for equipment in EtO service: those that do not have an LDAR program of 
any kind; and those that already conduct EPA Method 21 instrument 
monitoring. When evaluating the cost and emissions reductions for each 
facility, we calculated the incremental cost and reductions to meet 
Control Option 1 compared to a facility's baseline LDAR program. The 
memorandum 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, which is 
available in the docket for this rulemaking, summarizes the baseline 
LDAR program for each of the 33 CMAS EtO facilities evaluated for this 
control option and presents details on the methodologies used in this 
analysis.
    Table 2 of this preamble presents the nationwide impacts for 
requiring owners and operators of equipment in EtO service to perform 
EPA Method 21 monitoring in accordance with Control Option 1. Based on 
the costs and emission reductions, we are proposing to revise the CMAS 
NESHAP for equipment in EtO service to reflect Control Option 1 
pursuant to CAA section 112(d)(5).

[[Page 7953]]



  Table 2--Nationwide Emissions Reductions and Cost Impacts of Control Option 1 for Requiring EPA Method 21 Monitoring for Equipment in EtO Service at
                                                                 Certain Facilities \1\
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                              Total         Total
                                                Total      annualized    annualized                                         EtO cost         EtO cost
                                               capital      costs w/o    costs with     VOC emission     EtO emission   effectiveness w/  effectiveness
              Control option                 investment     recovery      recovery       reductions       reductions       o recovery     with recovery
                                                 ($)      credits  ($/  credits  ($/       (tpy)          (tpy) \2\       credits  ($/     credits  ($/
                                                               yr)           yr)                                              ton)             ton)
--------------------------------------------------------------------------------------------------------------------------------------------------------
1.........................................      511,000     1,261,000     1,129,400              146               83           15,100           13,500
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Facilities that would either become subject to the CMAS NESHAP if EtO is added to table 1 to 40 CFR part 63, subpart VVVVVV, as proposed, or are
  already subject to the CMAS NESHAP and emit EtO.
\2\ We note that EtO emission reductions from equipment leaks (and subsequent cost-effectiveness values for EtO from equipment leaks) differ from
  reductions expected to occur from reported emissions inventories due to use of model plants, engineering assumptions made to estimate baseline
  emissions, and uncertainties in how fugitive emissions may have been calculated for reported inventories compared to our model plants analysis (and
  are documented in the memorandum).

    The EPA is proposing to define equipment leaks ``in ethylene oxide 
service'' at 40 CFR 63.11502(b), by reference to the HON (40 CFR 
63.101). We are proposing Control Option 1 for equipment leaks in EtO 
service at 40 CFR 63.11495(a)(7). These proposed requirements would 
apply to all new and existing affected sources and specify that:
     All connectors in EtO service be monitored monthly at a 
leak definition of 100 ppmv with no skip period, and delay of repair is 
not allowed unless the equipment can be isolated such that it is no 
longer in EtO service (see 40 CFR 63.174(a)(3), (b)(3)(vi), and (g)(3), 
and 40 CFR 63.171(f)).
     All gas/vapor and light liquid valves in EtO service be 
monitored monthly at a leak definition of 100 ppmv with no skip period, 
and delay of repair is not allowed unless the equipment can be isolated 
such that it is no longer in EtO service (see 40 CFR 63.168(b)(2)(iv) 
and (d)(5), and 40 CFR 63.171(f)).
     All light liquid pumps in EtO service be monitored monthly 
at a leak definition of 500 ppmv, and delay of repair is not allowed 
unless the equipment can be isolated such that it is no longer in EtO 
service (see 40 CFR 63.163(a)(1)(iii), (b)(2)(iv), (c)(4), and (e)(7), 
and 40 CFR 63.171(f)).
2. Heat Exchange Systems in EtO Service
    Emissions of EtO from heat exchange systems occur when a heat 
exchanger's internal tubing material corrodes or cracks, allowing some 
process fluids to mix or become entrained with the cooling water. 
Pollutants (e.g., EtO) in the process fluids may subsequently be 
released from the cooling water into the atmosphere when the water is 
exposed to air (e.g., in a cooling tower for closed-loop systems or 
trenches/ponds in a once-through system). We provide more details about 
heat exchange systems, including how the CMAS NESHAP regulates them, in 
our technology review discussion (see section IV.C.2 of this preamble). 
Our CMAS heat exchange system technology review (see section IV.C.2 of 
this preamble) identified use of the Modified El Paso Method as a 
development in practice for heat exchange systems with a cooling water 
flow rate equal to or greater than 8,000 gallons per minute (gpm). 
Specifically, we identified the following control option for heat 
exchange systems: quarterly monitoring with the Modified El Paso 
Method, using a leak action level defined as a total strippable 
hydrocarbon concentration (as methane) in the stripping gas of 6.2 
ppmv. This option would also require repairing a leak no later than 45 
days after first identifying the leak, delay of repair within 120 days 
(except within no more than 30 days where a total strippable 
hydrocarbon concentration (as methane) in the stripping gas of 62 ppmv 
or higher is found), and re-monitoring at the monitoring location where 
the leak was identified to ensure that any leaks found are fixed.
    To assess what GACT standards may be appropriate if EtO is added to 
table 1 to 40 CFR part 63, subpart VVVVVV, we reviewed other 
rulemakings to identify the level of control required for heat exchange 
systems emitting EtO. As part of that review, we identified one rule 
requiring monitoring of heat exchange systems ``in ethylene oxide 
service.'' The EPA recently added EtO-specific requirements into the 
HON for heat exchange systems in EtO service that require more 
stringent monitoring frequency (weekly instead of quarterly) and repair 
of 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) (see 89 FR 42932, May 16, 2024). Additionally, delay 
of repair is not allowed unless there is no longer an active EtO leak 
once the heat exchange system is isolated and not in EtO service. A 
heat exchange system in EtO service means 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. If knowledge exists that suggests EtO 
could be present in a heat exchange system, then the heat exchange 
system is considered to be ``in ethylene oxide service'' unless the 
procedures specified in the HON at 40 CFR 63.109 are performed to 
demonstrate that the heat exchange system does not meet the definition 
of being ``in ethylene oxide service.'' Examples of information that 
could suggest EtO could be present in a heat exchange system 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.
    Given the EtO specific requirements in the HON for heat exchange 
systems in EtO service and minimal operational differences between heat 
exchange systems operating at SOCMI and CMAS facilities, we evaluated 
the following options in the selection of GACT for all heat exchange 
systems ``in ethylene oxide service'' that are located at CMAS:
     Control Option 1: quarterly monitoring (after an initial 
six months of monthly monitoring) with the Modified El Paso Method, 
using a leak action level defined as a total strippable hydrocarbon 
concentration (as methane) in the stripping gas of 6.2 ppmv; reduce the 
allowed amount of repair time from 45 days after finding a leak to 15 
days from the sampling date; and prohibit delay of repair.
     Control Option 2: same as Control Option 1, except monthly 
monitoring with the Modified El Paso Method instead of quarterly 
monitoring.
     Control Option 3: same as Control Option 1, except weekly 
monitoring with the Modified El Paso Method instead of quarterly 
monitoring. This option is required in the HON.
    The Modified El Paso Method is required and in use by sources 
regulated under other rulemakings including, but not limited to the 
MON, the HON, and the Petroleum Refineries NESHAP. The method works via 
air stripping and use of a flame ionization detector (FID), both of 
which are well understood

[[Page 7954]]

technologies in the chemical manufacturing sector and have been in use 
for decades. Given the widespread use of the fundamental technologies 
and method in other, similar chemical manufacturing facilities, we 
consider use of the Modified El Paso Method to be ``generally 
available.''
    We estimated the impacts of these Control Options using information 
from the original CMAS rulemaking.\17\ We estimated that 27 of the 33 
facilities that either would become subject to the CMAS NESHAP if EtO 
is added to table 1 to 40 CFR part 63, subpart VVVVVV or that are 
already subject to the CMAS NESHAP and emit EtO would be affected by 
Control Options 1 through 3; and we assumed each affected facility does 
not currently have an LDAR program for monitoring their cooling water. 
As part of our analysis, we also assumed all facilities monitoring 
quarterly for two or less heat exchange systems would elect to contract 
out the Modified El Paso monitoring (instead of purchasing a stripping 
column and FID analyzer and performing the monitoring in-house); 
however, facilities monitoring monthly or weekly would elect to 
purchase a stripping column and FID analyzer and perform in-house 
monitoring due to logistics. In addition, we assumed repairs could be 
performed by plugging a specific heat exchanger tube, and if a heat 
exchanger is leaking to the extent that it needs to be replaced, then 
it is effectively at the end of its useful life. Therefore, we 
determined that the cost of replacing a heat exchanger is an 
operational cost that would be incurred by the facility because of 
routine maintenance and equipment replacement, and it is not 
attributable to the Control Options.
---------------------------------------------------------------------------

    \17\ EPA, 2008. Control Options and Impacts for Cooling Tower 
Control Measures Chemical Manufacturing Area Source Standards. 
September 5, 2008. Docket ID No. EPA-HQ-OAR-2008-0334-0003; and EPA, 
2009. Update to the Control Options and Impacts for Heat Exchange 
System Control Measures for Promulgation Chemical Manufacturing Area 
Source Standards. May 5, 2009. Docket ID No. EPA-HQ-OAR-2008-0334-
0081.
---------------------------------------------------------------------------

    Table 3 of this preamble presents the nationwide impacts for 
requiring owners and operators of heat exchange systems in EtO service 
to use the Modified El Paso Method and repair leaks of total strippable 
hydrocarbon concentration (as methane) in accordance with Control 
Options 1 through 3. See the document titled Clean Air Act Section 
112(d)(5) GACT Standard Analysis for Heat Exchange Systems that Emit 
Ethylene Oxide and Section 112(d)(6) Technology Review for Heat 
Exchange Systems Associated with Chemical Manufacturing Process Units 
at Area Sources Subject to the CMAS NESHAP, which is available in the 
docket for this rulemaking, for details on the assumptions and 
methodologies used in this analysis.
    While all Control Options were identified as cost effective based 
on values accepted as part of other recent rulemakings regulating EtO 
emissions (see 89 FR 24090, April 5, 2024, for the commercial 
sterilizer rulemaking), the potency of EtO as a carcinogen, and 
historic cost-effectiveness values accepted for highly toxic HAP (such 
as hexavalent chromium), there are no records in the emissions 
inventory from heat exchangers in EtO service. We note that leaks from 
heat exchange systems handling EtO can still occur, even if there are 
no specific emissions records in the inventory. This absence of records 
is likely because most facilities emitting EtO have not been required 
to monitor leaks in their heat exchange systems. Consequently, the 
impacts associated with controlling these emissions are less certain 
due to the lack of records. In addition, there are concerns that 
monthly or weekly monitoring of heat exchangers in EtO service would be 
significantly more burdensome for area sources than major sources. 
Major sources may have additional capital and personnel bandwidth to 
accommodate installation and operation of a stripping column and lab 
equipment (such as a gas chromatograph/mass spectroscopy unit) 
necessary for in-house analysis compared to area sources who may not 
have previously been subject to any monitoring of heat exchange 
systems. As such, based on the costs, emissions reductions, and 
uncertainties, we are proposing that Control Option 1 represents GACT 
for heat exchange systems in EtO service. However, we are soliciting 
comments and data on whether more frequent monitoring (i.e., Control 
Options 2 and 3) would be appropriate for CMAS considering the proposed 
addition of EtO to table 1 to 40 CFR part 63, subpart VVVVVV.

     Table 3--Nationwide Emissions Reductions and Cost Impacts of Control Options 1 Through 3 for Requiring the Modified El Paso Method for Heat Exchange Systems in EtO Service at Certain
                                                                                         Facilities \1\
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                   Total        Total
                                                                      Total      annualized   annualized                                      EtO cost          EtO cost        EtO Incremental
                                                                     capital     costs w/o    costs with   VOC emission    EtO emission   effectiveness  w/   effectiveness   cost effectiveness
                          Control option                            investment    recovery     recovery     reductions      reductions       o recovery       with recovery      with recovery
                                                                       ($)      credits  ($/ credits  ($/      (tpy)           (tpy)      credits  ($/ton)  credits  ($/ton)    credits  (from
                                                                                    yr)          yr)                                                                          option 1)  ($/ton)
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
1................................................................      122,000      157,000      117,900            43.4            24.8             6,300             4,700  ..................
2................................................................      122,000      359,400      319,500            44.3            25.3            14,200            12,500             388,500
3................................................................      122,000    1,371,500    1,331,300            44.7            25.5            52,300            52,200           1,688,800
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Facilities that would either become subject to the CMAS NESHAP if EtO is added to table 1 to 40 CFR part 63, subpart VVVVVV, as proposed, or are already subject to the CMAS NESHAP and emit
  EtO.

    The EPA is proposing to define a heat exchange system ``in ethylene 
oxide service'' at 40 CFR 63.11502(b), by reference to the HON (40 CFR 
63.101). We are proposing Control Option 1 at 40 CFR 63.11499(e) and 
item 2 of table 8 to the CMAS NESHAP, by reference to the HON (40 CFR 
63.104(a), (f) through (i), and (k)), to specify quarterly monitoring 
(after an initial six months of monthly monitoring) for leaks for all 
new and existing affected sources with heat exchange systems in EtO 
service using the Modified El Paso Method, and if a leak is found, we 
are proposing owners and operators must repair the leak to below the 
applicable leak action level as soon as practicable, but no later than 
15 days after the sample was collected with no delay of repair allowed 
(see 40 CFR 63.104(h)(6)).
3. Process Vents and Storage Tanks in EtO Service
    Emissions of EtO can occur from several types of gas streams 
associated with CMAS processes, such as distillation columns, 
evaporator vents, and vacuum operations, as well as during vapor 
displacements and heating losses. CMAS storage tanks are used to store 
liquid and gaseous feedstocks for use in a process, as well as to store

[[Page 7955]]

liquid and gaseous products from a process. EtO is typically stored 
under pressure as a liquified gas but may also be found in small 
amounts in atmospheric storage tanks storing liquid products that are 
formed with EtO as a reactant in their production. Typical emissions 
from atmospheric storage tanks occur from working and breathing losses 
while pressure vessels are considered closed systems and, if properly 
maintained and operated, should have virtually no emissions. In some 
instances, pressurized vessels also could use a blanket of inert gas, 
most often nitrogen, to maintain a non-decomposable vapor space, and 
continuous purge of vapor space from non-loading operations could also 
lead to emissions from storage tanks. We provide details about process 
vents and storage tanks, including how the CMAS NESHAP regulates them, 
in our technology review discussion (see sections IV.C.3 and IV.C.4 of 
this preamble, respectively).
    To assess what GACT standards may be appropriate, we reviewed other 
rulemakings to identify the level of control required for process vents 
and storage vessels emitting EtO. As part of that review, we identified 
two rules requiring stringent control of emissions from vents and 
process tanks ``in ethylene oxide service.'' The EPA recently added 
EtO-specific requirements into the MON and HON for process vents and 
storage vessels in EtO service (see 85 FR 49084, August 12, 2020, and 
89 FR 42932, May 16, 2024, respectively). We note that the MON and HON 
use the term ``storage vessel'' in lieu of ``storage tank'' which is 
used in the CMAS NESHAP. According to the MON and HON, a process vent 
in EtO service is a process vent that contains a concentration of 
greater than or equal to 1 ppmv undiluted EtO when uncontrolled, and 
when all process vents within the process are combined, the sum of 
uncontrolled EtO emissions are greater than or equal to 5 pounds per 
year (lb/yr) (2.27 kilogram per year, kg/yr). A storage vessel in EtO 
service means a storage vessel of any capacity and vapor pressure 
storing a liquid that is at least 0.1 percent by weight of EtO. The 
EtO-specific standards established for the Miscellaneous Organic 
Chemical Manufacturing and SOCMI source categories are as follows:
     Requirements that owners and operators must reduce 
emissions of EtO from process vents in EtO service by either: (1) 
venting emissions through a closed vent system to a control device that 
reduces EtO by greater than or equal to 99.9 percent by weight, to a 
concentration less than 1 ppmv for each process vent, or to less than 5 
lb/yr for all combined process vents per CMPU; or (2) venting emissions 
through a closed vent system to a flare meeting certain new operating 
and monitoring requirements for flares; and
     Requirements that owners and operators must reduce 
emissions of EtO from storage tanks in EtO service by either: (1) 
venting emissions through a closed vent system to a 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 storage tank vent; or (2) 
venting emissions through a closed vent system to a flare meeting 
certain new operating and monitoring requirements for flares.
    Given the EtO specific requirements in the MON and HON for process 
vents and storage vessels in EtO service and minimal operational 
differences between an APCD controlling emissions from process vents or 
storage vessels/tanks at MON, SOCMI, and CMAS facilities, we evaluated 
a Control Option to represent GACT for process vents and storage tanks 
that are ``in ethylene oxide service'' that would require owners and 
operators at certain CMAS (i.e., facilities that would either become 
subject to the CMAS NESHAP if EtO is added to table 1 to 40 CFR part 
63, subpart VVVVVV, as proposed, or are already subject to the CMAS 
NESHAP and emit EtO) to reduce emissions of EtO by 99.9 percent from 
process vents and storage tanks that are ``in ethylene oxide service'' 
as defined by the MON and HON (i.e., Control Option 1). Our evaluation 
considered the use of a thermal oxidizer achieving a 99.9 percent 
reduction of EtO emissions to control emissions from process vents and 
storage tanks in EtO service, as it is common for the same control 
device to control emissions from both emission sources at chemical 
plants. Control Option 1 reflects the EtO-specific requirements in the 
MON and HON for process vents and storage vessels in EtO service; 
therefore, it would apply to process vents in which the uncontrolled, 
undiluted EtO emissions from all process vents in a CMPU are greater 
than or equal to 5 lb/yr and the concentration of the uncontrolled, 
undiluted stream is greater than or equal to 1 ppmv. This Control 
Option would also apply to storage tanks of any capacity and vapor 
pressure storing a liquid that is at least 0.1 percent by weight of 
EtO.
    We find this Control Option to be ``generally available'' per the 
language of CAA section 112(d)(5). Control devices include a wide array 
of potential technologies and so a facility may use whatever methods 
are available to achieve the 99.9 percent by weight reduction in EtO 
emissions. Thermal oxidizers, which we assumed will be installed by 
facilities needing to meet the proposed standards, are used to control 
emissions from process vents and storage tanks at sources regulated 
under other rulemakings including, but not limited to, the MON and the 
HON and have been in use in industry for decades. In addition, the CMAS 
NESHAP already allows for the venting of emissions through a closed 
vent system to a flare for both process vents and storage tanks. Given 
the widespread use of a readily available control technology such as a 
thermal oxidizer in other, similar chemical manufacturing facilities, 
we consider this Control Option of proposing a 99.9 percent by weight 
reduction of EtO emissions from process vents and storage tanks to be 
``generally available.''
    To determine which emission points at facilities would need 
additional control of EtO emissions, we reviewed the CMAS emissions 
inventory data (see section II.C.2 of this preamble). For each process 
vent and storage tank emission point record with EtO emissions in the 
CMAS emissions inventory, we determined whether it was controlled by a 
non-flare combustion device, a non-combustion control device, a non-
combustion control device able to achieve 99.9 percent emissions 
reduction, or was uncontrolled. There are no process vent or storage 
tank emission point records associated with a non-flare combustion 
device; however, for emission point records that are controlled by a 
non-combustion control device, our impacts analyses assumed that none 
of the facilities with existing non-combustion controls would be able 
to achieve 99.9 percent control of EtO, unless a stack test or data 
provided by a state agency confirmed otherwise. Therefore, we treated 
non-combustion control devices unable to achieve 99.9 percent control 
and uncontrolled emission point records in the same manner and assumed 
that each would need to be controlled by a thermal oxidizer. Some 
facilities that would need to install a thermal oxidizer to control EtO 
have multiple process vent and/or storage tank emission points with EtO 
emissions. Rather than costing out multiple thermal oxidizers for these 
facilities, we assumed they would combine the streams together and 
install a single thermal oxidizer (to control all EtO emissions), as is 
commonly done at chemical plants. We also recognize that some emission 
points could possibly achieve a 99.9 percent reduction in EtO emissions 
by upgrading or installing a

[[Page 7956]]

new scrubber system instead of a new thermal oxidizer; and upgrading or 
installing a new scrubber system would likely cost less than installing 
a new thermal oxidizer. However, for simplicity, we only evaluated the 
use of a thermal oxidizer to meet the Control Option because using 
thermal oxidizers is common for controlling emissions from both process 
vents and storage tanks in EtO service at chemical plants. Ultimately, 
we determined that seven facilities would be impacted by Control Option 
1 to reduce emissions of EtO by 99.9 percent from process vents and 
storage tanks that are ``in ethylene oxide service'' as defined by the 
MON and HON (1 of these 7 facilities is already subject to the CMAS 
NESHAP and the remaining 6 facilities would become subject to the CMAS 
NESHAP if EtO is added to table 1 to 40 CFR part 63, subpart VVVVVV, as 
proposed). We estimated costs to install a thermal oxidizer using the 
EPA's control cost template.\18\ Table 4 of this preamble presents the 
nationwide impacts of Control Option 1, requiring owners and operators 
to reduce emissions of EtO by 99.9 percent from process vents and 
storage tanks that are ``in ethylene oxide service'' as defined by the 
MON and HON. See the document titled Clean Air Act Section 112(d)(5) 
GACT Standard Analysis for Process Vents and Storage Tanks that Emit 
Ethylene Oxide and Section 112(d)(6) Technology Review for Process 
Vents and Storage Tanks Associated with Chemical Manufacturing Process 
Units at Area Sources Subject to the CMAS NESHAP, which is available in 
the docket for this rulemaking, for details on the assumptions and 
methodologies used in this analysis. Based on the costs and emission 
reductions for Control Option 1, we are proposing to revise the CMAS 
NESHAP for process vents and storage tanks in EtO service to reflect 
Control Option 1 pursuant to CAA section 112(d)(5). The cost 
effectiveness of this Control Option is within the range of values that 
have been accepted in other recent rulemakings regulating EtO emissions 
such as the commercial sterilizer rulemaking (see 89 FR 24090, April 5, 
2024) \19\ and is within the range of historic cost-effectiveness 
values that have been accepted for highly toxic HAP (such as hexavalent 
chromium).\20\ EtO is similarly toxic due to its potency as a 
carcinogen. As such, we find that this Control Option is cost 
effective.
---------------------------------------------------------------------------

    \18\ Refer to the file ``Incinerators and Oxidizers Calculation 
Spreadsheet (note: updated on 1/16/2018) (xlsm)'' which follows the 
methodology from the sixth edition of the EPA Air Pollution Control 
Cost Manual and can be found at the following website: https://www.epa.gov/economic-and-cost-analysis-air-pollution-regulations/cost-reports-and-guidance-air-pollution.
    \19\ The EPA finalized EtO emissions standards in the RTR for 
sterilization facilities with costs estimated to be as much as 
$17,500,000 per ton EtO.
    \20\ For small hard chromium electroplating, to provide an ample 
margin of safety, the EPA finalized a requirement with a cost 
effectiveness of $15,000 per lb ($30,000,000 per ton) (see 77 FR 
58227-8 and FR 77 58239, September 19, 2012).

Table 4--Nationwide Emissions Reductions and Cost Impacts of Control Option 1 for Requiring 99.9 Percent Control
                   of Process Vents and Storage Tanks in EtO Service at Certain Facilities \1\
----------------------------------------------------------------------------------------------------------------
                                                                                                    EtO cost
           Control option               Total capital     Total annualized     EtO emission    effectiveness ($/
                                        investment ($)      costs ($/yr)     reductions (tpy)         ton)
----------------------------------------------------------------------------------------------------------------
1...................................         1,395,000          2,126,000                1.1          1,933,000
----------------------------------------------------------------------------------------------------------------
\1\ Facilities that would either become subject to the CMAS NESHAP if EtO is added to table 1 to 40 CFR part 63,
  subpart VVVVVV, as proposed, or are already subject to the CMAS NESHAP and emit EtO.

    The EPA is proposing to define a process vent ``in ethylene oxide 
service'' at 40 CFR 63.11502(b), by reference to the HON (40 CFR 
63.101). We are proposing Control Option 1 for all new and existing 
affected sources with process vents in EtO service at 40 CFR 
63.11496(j), item 4 of table 2 to the CMAS NESHAP (for batch process 
vents), and item 4 of table 3 to the CMAS NESHAP (for continuous 
process vents), by reference to the HON. These proposed requirements 
specify that owners and operators of process vents in EtO service must 
reduce emissions of EtO by venting emissions through a closed vent 
system to a flare in accordance with the requirements in 40 CFR 63.108 
and 40 CFR 63.124 (see section IV.A.6 of this preamble for additional 
details regarding our proposed requirements for flares that emit EtO), 
or to a 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 or to less than 5 lb/yr for all combined process vents 
within the process in accordance with the requirements in 40 CFR 
63.124.
    The EPA is proposing to define a storage tank (vessel) ``in 
ethylene oxide service'' at 40 CFR 63.11502(b), by reference to the HON 
(40 CFR 63.101). We are also proposing that the exemption for ``tanks 
storing organic liquids containing HAP only as impurities'' listed in 
the definition of ``storage tank'' at 40 CFR 63.11502(b) does not apply 
for storage tanks in EtO service. We are also proposing Control Option 
1 for storage tanks in EtO service at 40 CFR 63.11497(e) and item 5 of 
table 5 to the CMAS NESHAP, by reference to the HON. These proposed 
requirements specify that owners and operators of storage tanks in EtO 
service must reduce emissions of EtO by venting emissions through a 
closed vent system to a flare in accordance with the requirements in 40 
CFR 63.108 and 40 CFR 63.124 (see section IV.A.6 of this preamble for 
additional details regarding our proposed requirements for flares that 
emit EtO), or to a 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 storage tank vent in accordance with the requirements in 40 
CFR 63.124.
    In addition, given that 40 CFR 63.124 requires owners and operators 
to comply with the HON leak inspection requirements in 40 CFR 63.148 
and the delay of repair provisions associated with these inspection 
requirements (i.e., 40 CFR 63.148(e)) rely on a definition for 
``shutdown'' that does not include batch processes, we are also 
proposing to substitute the use of ``shutdown'' with language at 40 CFR 
63.11496(j)(5)(iv) and 40 CFR 63.11497(e)(5)(iv) to accommodate both 
continuous and batch processes. We are proposing that for 40 CFR 
63.148(e), the term ``shutdown'' for a continuous operation, means the 
cessation of the unit operation for any purpose. Shutdown begins with 
the initiation of steps as described in a written standard operating 
procedure or shutdown plan to cease normal/stable operation (e.g., 
reducing or immediately stopping feed). For batch operations, we are 
proposing that for 40 CFR 63.148(e), the term ``shutdown'' means the 
cessation of a

[[Page 7957]]

batch operation except shutdown does not apply to cessation of batch 
operations at the end of a campaign or between batches within a 
campaign when the steps taken to cease operation are normal operations.
    Finally, we are also proposing to remove the option to allow use of 
a design evaluation in lieu of performance testing to demonstrate 
compliance for controlling process vents and storage tanks that are in 
EtO service. In addition, owners or operators that choose to control 
emissions with a non-flare control device would be required to conduct 
an initial performance test on each control device in EtO service to 
verify performance at the required level of control, and would also be 
required to conduct periodic performance testing on non-flare control 
devices in EtO service every 5 years (see proposed 40 CFR 63.11496(j) 
and 40 CFR 63.11497(e) by reference to 40 CFR 63.124).
4. Wastewater in EtO Service
    EtO is emitted into the air from wastewater collection, storage, 
and treatment systems that are uncovered or open to the atmosphere 
through volatilization of the compound at the liquid surface. The rate 
of volatilization is related directly to the speed of the air flow over 
the water surface. We provide more details about wastewater streams, 
including how the CMAS NESHAP regulates them, in our technology review 
discussion (see section IV.C.5 of this preamble).
    To assess what GACT standards may be appropriate for wastewater in 
EtO service, we reviewed other rulemakings to identify the level of 
control required for wastewater emitting EtO. As part of that review, 
we identified one rule requiring control of emissions from wastewater 
``in ethylene oxide service.'' In the HON rulemaking, the EPA recently 
added EtO-specific requirements for wastewater streams in EtO service 
(see 89 FR 42932, May 16, 2024). These standards require owners and 
operators to manage and treat existing and new wastewater streams with 
total annual average concentration of EtO greater than or equal to 1 
ppmw at any flow rate. As such, we evaluated a Control Option to 
represent GACT for wastewater streams that are ``in ethylene oxide 
service'' that would require owners and operators at certain CMAS 
(those that would either become subject to the CMAS NESHAP if EtO is 
added to table 1 to 40 CFR part 63, subpart VVVVVV, as proposed, or are 
already subject to the CMAS NESHAP and emit EtO) to comply with the HON 
Group 1 wastewater requirements for wastewater streams that are ``in 
ethylene oxide service'' as defined by the HON (i.e., Control Option 
1).
    The HON specifies performance standards for treatment processes 
managing Group 1 wastewater streams including performance standards for 
open or closed biological treatment systems or a design steam stripper 
with vent control. For APCDs (e.g., thermal oxidizers) used to control 
emissions from collection system components, steam strippers, or closed 
biological treatment, the HON provides owners or operators several 
compliance options, including a 95 percent destruction efficiency 
standard, a 20 ppmv outlet concentration standard, or design 
specifications for temperature and residence time. Given the EtO 
specific requirements in the HON at 40 CFR 63.138(b)(3) and (c)(3) for 
wastewater streams in EtO service to reduce, by removal or destruction, 
the concentration of EtO to a level less than 1 ppmw and minimal 
operational differences between controlling emissions from HON CMPUs 
and CMAS CMPUs, we evaluated the use of steam stripping to comply with 
Control Option 1. While we acknowledge EtO can be biodegraded, the 
compound is not on table 37 to subpart G of the HON suggesting that it 
is not a readily biodegradable compound when using a biological 
treatment method, and EtO would need to be stripped out of the 
wastewater to meet the standard at 40 CFR 63.138(b)(3) and (c)(3). 
Therefore, we evaluated Control Option 1 using a steam stripper 
achieving a 98 percent reduction of EtO emissions (based on the 
fraction removed (Fr) value of EtO \21\ in table 9 to subpart G of the 
HON).
---------------------------------------------------------------------------

    \21\ The Fr is the fraction of a HAP that is stripped from 
wastewater and is an indicator of the extent to which a HAP is 
effectively removed during the steam stripping process, which for 
EtO is 98 percent.
---------------------------------------------------------------------------

    We find Control Option 1 to be ``generally available'' per the 
language of CAA section 112(d)(5). Steam strippers are used to control 
emissions from wastewater streams at sources regulated under other 
rulemakings including, but not limited to, the MON and the HON. In 
addition, steam stripping was evaluated as part of the original 
rulemaking and is currently a method of compliance for controlling 
certain CMPU wastewater streams. Given the widespread use of this 
control technology in other, similar chemical manufacturing facilities, 
and current applicability of the technology to certain CMAS wastewater 
streams, we consider this Control Option of proposing the use of steam 
strippers to control EtO emissions from wastewater to be ``generally 
available.''
    We reviewed the CMAS emissions inventory data (see section II.C.2 
of this preamble) as well as air permits and determined that there are 
4 CMAS facilities that have wastewater processes that use and emit EtO 
and therefore would be impacted by Control Option 1. To evaluate the 
impacts of requiring these facilities to meet Control Option 1, we used 
PEPO-specific wastewater data submitted in response to the EPA's 2022 
CAA section 114 request (see section II.C.3 of this preamble). We used 
the PEPO-specific wastewater data rather than HON-specific data because 
for EtO processes, CMAS CMPUs are more like PEPO PMPUs given that both 
CMAS CMPUs and PEPO PMPUs use EtO as a reactant (often in batch 
reactions to make a product), whereas HON CMPUs produce EtO and are 
continuous. In addition, we removed all PEPO-specific wastewater data 
that could not be representative of an area source (based on the amount 
of HAP emissions that could potentially be emitted to the atmosphere 
from the wastewater streams); and therefore, not representative of a 
CMAS facility. We estimated costs to install a steam stripper using the 
cost algorithm for wastewater stripper steam requirements used for the 
development of the HON.\22\ Table 5 of this preamble presents the 
nationwide impacts of Control Option 1, requiring owners and operators 
to manage and treat existing and new wastewater streams with total 
annual average concentration of EtO greater than or equal to 1 ppmw at 
any flow rate in accordance with HON Group 1 wastewater requirements. 
See the document titled Clean Air Act Section 112(d)(5) GACT Standard 
Analysis for Wastewater Streams that Emit Ethylene Oxide and Clean Air 
Act Section 112(d)(6) Technology Review for Wastewater Systems 
Associated with Chemical Manufacturing Process Units at Area Sources 
Subject to the CMAS NESHAP, which is available in the docket for this 
rulemaking, for details on the assumptions and methodologies used in 
this analysis. Based on the costs and emission reductions for Control 
Option 1, we are proposing to revise the CMAS NESHAP for wastewater in 
EtO service to reflect Control Option 1 pursuant to CAA section 
112(d)(5). The

[[Page 7958]]

cost effectiveness of this Control Option is within the range of values 
that have been accepted in other recent rulemakings regulating EtO 
emissions, such as the commercial sterilizer rulemaking (see 89 FR 
24090, April 5, 2024) \23\, and is within the range of historic cost-
effectiveness values that have been accepted for highly toxic HAP (such 
as hexavalent chromium).\24\ EtO is similarly toxic due to its potency 
as a carcinogen. As such, we find that this Control Option is cost 
effective.
---------------------------------------------------------------------------

    \22\ EPA, 1992a. Hazardous Air Pollutant Emissions from Process 
Units in the Synthetic Organic Chemical Manufacturing Industry--
Background Information for Proposed Standards, Volume 1B: Control 
Technologies. EPA-453/D-92-016b. November 1992; and EPA, 1992b. 
Hazardous Air Pollutant Emissions from Process Units in the 
Synthetic Organic Chemical Manufacturing Industry--Background 
Information for Proposed Standards, Volume 1C: Model Emission 
Sources. EPA-453/D-92-016c. November 1992.
    \23\ See footnote 19.
    \24\ See footnote 20.

     Table 5--Nationwide Emissions Reductions and Cost Impacts of Control Option 1 for Requiring Control of
                               Wastewater in EtO Service at Certain Facilities \1\
----------------------------------------------------------------------------------------------------------------
                                                                               EtO emission         EtO cost
           Control option               Total capital     Total annualized   reductions (tpy)  effectiveness ($/
                                        investment ($)      costs ($/yr)           \2\                ton)
----------------------------------------------------------------------------------------------------------------
1...................................        12,899,400          5,471,300                8.3            659,200
----------------------------------------------------------------------------------------------------------------
\1\ Facilities that would either become subject to the CMAS NESHAP if EtO is added to table 1 to 40 CFR part 63,
  subpart VVVVVV, as proposed, or are already subject to the CMAS NESHAP and emit EtO.
\2\ We note that EtO emission reductions from wastewater (and subsequent cost-effectiveness values for EtO from
  wastewater) differ from reductions expected to occur from reported emissions inventories due to use of model
  plants, engineering assumptions made to estimate baseline emissions, and uncertainties in how fugitive
  emissions may have been calculated for reported inventories compared to our model plants analysis (and are
  documented in the memorandum).

    The EPA is proposing to define a wastewater stream ``in ethylene 
oxide service'' at 40 CFR 63.11502(b), by reference to the HON (40 CFR 
63.101). We are proposing Control Option 1 for all new and existing 
affected sources with wastewater streams in EtO service at 40 CFR 
63.11498(c) and item 3 of table 6 to the CMAS NESHAP, by reference to 
the HON. These proposed requirements specify that owners and operators 
of wastewater in EtO service must reduce, by removal or destruction, 
the concentration of ethylene oxide in existing and new wastewater 
streams (i.e., wastewater streams with total annual average 
concentration of EtO greater than or equal to 1 ppmw at any flow rate) 
to a level less than 1 ppmw as determined by the procedures specified 
in Sec.  63.145(b) and in accordance with the Group 1 wastewater stream 
requirements of Sec. Sec.  63.133 through 63.148 and the requirements 
referenced therein. Additionally, we are aware that some chemical 
manufacturing facilities dispose of certain wastewater streams that 
contain EtO by adding those wastewaters to the cooling water of their 
heat exchange systems, rather than considering those EtO-containing 
streams to be potential sources of wastewater. To eliminate these types 
of EtO emissions from wastewater being injected into heat exchange 
systems, we are also proposing to prohibit owners and operators from 
injecting water into or disposing of water through any heat exchange 
system in a CMPU meeting the conditions of 40 CFR 63.11494 if the water 
contains any amount of EtO, has been in contact with any process stream 
containing EtO, or the water is considered wastewater as defined in 40 
CFR 63.11502 (see proposed 40 CFR 63.11495(b)(4) and items 1.c and 2 of 
table 8 to the CMAS NESHAP).
5. Standards for Transfer Operations That Emit EtO
    The EPA includes transfer operations as part of the equipment 
collection that makes up a CMPU (see 40 CFR 63.11494(b)). According to 
the CMAS NESHAP, transfer operations involve loading liquid containing 
organic HAP into tank trucks and rail cars from a transfer rack. This 
does not include loading into other containers like cans, drums, and 
totes.
    The CMAS NESHAP defines a transfer rack as the system used to load 
organic liquids into tank trucks and railcars at a single location. 
This system includes all necessary loading arms, pumps, meters, shutoff 
valves, relief valves, and other piping and equipment. Transfer 
equipment that do not share common piping, valves, and other equipment 
are considered separate transfer racks.
    The CMAS NESHAP regulates transfer operations through specific 
management practices. According to 40 CFR 63.11495(a)(2), owners and 
operators must use one of the following methods to control total 
organic HAP emissions when transferring certain liquids (those 
containing any organic HAP listed in table 1 to 40 CFR part 63, subpart 
VVVVVV) to tank trucks or railcars: (1) submerged loading or bottom 
loading; (2) routing emissions to a fuel gas system or process; (3) 
vapor balancing back to the storage tank or another storage tank 
connected by a common header; or (4) venting through a closed vent 
system to a control device.
    Since we are proposing to add EtO to table 1 to 40 CFR part 63, 
subpart VVVVVV, owners and operators of new and existing affected 
sources with transferring liquids containing EtO to tank trucks or 
railcars would be subject to these same management practices. We are 
proposing that these management practices reflect GACT for these 
transfer operations. We anticipate that all facilities that may become 
subject to the CMAS NESHAP if EtO were to be added to table 1 to 40 CFR 
part 63, subpart VVVVVV already use at least one of these management 
practices when transferring liquids containing EtO to tank trucks or 
railcars. Therefore, we do not expect any additional costs from this 
proposed GACT standard.
    The EPA is soliciting comments and data on the proposed transfer 
operation practices.
6. Standards for Flares That Emit EtO
    As previously discussed in section IV.A.3 of this preamble, the EPA 
is proposing to add specific requirements for EtO to the CMAS NESHAP 
for batch process vents, continuous process vents, and storage tanks in 
EtO service. Each of these requirements mandates 99.9 percent control, 
reduction in concentration to less than 1 ppmw, or the use of a flare. 
These requirements are based on EtO-specific requirements in the MON 
and HON. If a flare is used to meet the MON and HON standards for 
process vents and storage tanks in EtO service, the owner or operator 
must comply with several operational and monitoring requirements that 
are reflective of requirements for petroleum refinery flares which 
address: (1) the presence of a pilot flame; (2) visible emissions; (3) 
flare tip velocity; (4) net heating value of flare combustion zone gas; 
and (5) net heating value dilution parameter (if the flare actively 
receives perimeter assist air). More details about these requirements 
are provided in our

[[Page 7959]]

technology review discussion (see section IV.C.6 of this preamble). As 
such, we evaluated the option (i.e., Control Option 1) to require 
flares used to comply with the proposed GACT standards for process 
vents and storage tanks in EtO service to meet the same operational and 
monitoring requirements included in the MON and HON.
    Control Option 1 requires various monitoring equipment (i.e., 
hydrogen analyzers, calorimeters, and flow monitors) be installed on 
the flare vent gas stream header and/or steam- or air-assist header. 
Flares are used to control emissions from sources such as process vents 
and storage tanks regulated under other rulemakings including, but not 
limited to, the HON and the MON. The HON and MON apply to chemical 
manufacturing facilities and already require these types of monitoring 
equipment. Given the widespread use of this monitoring equipment in 
other, similar chemical manufacturing facilities, we consider Control 
Option 1, which includes the use of hydrogen analyzers, calorimeters, 
and flow monitors, to be ``generally available'' per the language of 
CAA section 112(d)(5).
    Using information from the CMAS emissions inventory data (see 
section II.C.2 of this preamble), we estimated there are only two 
flares at two different facilities that would be impacted by Control 
Option 1 (one of the facilities is already subject to the CMAS NESHAP 
and the other facility would become subject to the CMAS NESHAP if EtO 
is added to table 1 to 40 CFR part 63, subpart VVVVVV, as proposed). We 
estimated costs for each flare for a given facility, considering 
current monitoring systems already installed on each individual flare. 
Given that the same type of equipment is used for flares in the CMAS 
categories and for the petroleum refinery sector, we estimated costs 
for any additional monitoring systems needed based on installed costs 
received from petroleum refineries. If those installed costs were 
unavailable, we estimated costs based on vendor-purchased equipment. 
The baseline emission estimate and the emission reductions achieved by 
Control Option 1 were estimated based on the CMAS emissions inventory 
data (see section II.C.2 of this preamble) and current vent gas and 
steam flow data submitted by industry representatives.\25\ The results 
of the impact estimates are summarized in table 6 of this preamble for 
Control Option 1. See the document titled Clean Air Act Section 
112(d)(5) GACT Standard Analysis for Flares that Emit Ethylene Oxide 
and Section 112(d)(6) Technology Review for Flares Associated with 
Chemical Manufacturing Process Units at Area Sources Subject to the 
CMAS NESHAP, which is available in the docket for this rulemaking, for 
details on the assumptions and methodologies used in this analysis. 
Based on the costs and emission reductions for Control Option 1, we are 
proposing to revise the CMAS NESHAP for flares used to comply with the 
proposed GACT standards for process vents and storage tanks in EtO 
service to reflect Control Option 1 pursuant to CAA section 112(d)(5). 
The cost-effectiveness of this Control Option is within the range of 
values that have been accepted in other recent rulemakings regulating 
EtO emissions such as the commercial sterilizer rulemaking (see 89 FR 
24090, April 5, 2024) \26\ and is within range of historic cost-
effectiveness values that have been accepted for highly toxic HAP (such 
as hexavalent chromium).\27\ EtO is similarly toxic due to its potency 
as a carcinogen. As such, we find that this Control Option is cost-
effective.
---------------------------------------------------------------------------

    \25\ To estimate the baseline control efficiency of volatile 
organic compounds (VOC) and HAP anticipated by applying Control 
Option 1, we reviewed data submitted to the EPA in 2011 by the 
American Petroleum Institute (API), the American Chemistry Council 
(ACC), and the National Petrochemical and Refiners Association 
(NPRA), now known as the American Fuels and Petrochemical 
Manufacturers (AFPM). This dataset includes detailed hourly 
operational information for 38 steam-assisted flares, characterizing 
different operating conditions by waste gas flow rate, steam flow 
rate, waste gas composition, and duration of that operating 
condition.
    \26\ See footnote 19.
    \27\ See footnote 20.

  Table 6--Nationwide Emissions Reductions and Cost Impacts of Control Option 1 for Requiring the Suite of Operational and Monitoring Requirements for
                                                       Flares That Emit EtO at CMAS Facilities \1\
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                                                            EtO cost
                      Control option                         Total capital     Total annualized     VOC emission       EtO emission    effectiveness ($/
                                                             investment ($)      costs ($/yr)     reductions (tpy)   reductions (tpy)         ton)
--------------------------------------------------------------------------------------------------------------------------------------------------------
1........................................................         3,770,000            960,000               12.8               1.56            606,700
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Facilities that would either become subject to the CMAS NESHAP if EtO is added to table 1 to 40 CFR part 63, subpart VVVVVV, as proposed, or are
  already subject to the CMAS NESHAP and emit EtO.

    We are proposing Control Option 1 for flares at new and existing 
affected sources that are used to comply with the proposed GACT 
standards for process vents and storage tanks in EtO service at item 
4.a of table 2 to the CMAS NESHAP, item 4.a of table 3 to the CMAS 
NESHAP, item 5.a of table 5 to the CMAS NESHAP, and 40 CFR 
63.11497(f)(5), all by reference to the HON (40 CFR 63.108 and 40 CFR 
63.124). These proposed requirements specify that owners and operators 
that choose to use a flare to comply with the proposed standards for 
process vents and storage tanks in EtO service as described in section 
IV.A.3 of this preamble must vent emissions through a closed vent 
system and meet the applicable requirements for flares as specified in 
40 CFR 63.670 and 63.671, including the provisions in tables 12 and 13 
to 40 CFR part 63, subpart CC (i.e., the suite of operational and 
monitoring requirements for refinery flares). In addition, we are 
proposing amendments to 40 CFR 63.11501(c)(2)(iii) and (c)(4)(vii) to 
align the recordkeeping requirements with this proposed Control Option.
    We also note that we are proposing an LDAR program for equipment 
leaks at 40 CFR 63.11495(a)(6) and (7) (see sections IV.A.1 and IV.C.1 
of this preamble). Part of this LDAR program requires owners and 
operators that vent equipment leak emissions through a closed vent 
system to a flare used to control equipment leaks in EtO service, to 
comply with the same suite of operational and monitoring requirements 
for flares as we are proposing for flares used to comply with the 
proposed GACT standards for process vents and storage tanks in EtO 
service (see proposed 40 CFR 63.11495(a)(7)). Given that we only 
identified two flares in the CMAS emissions inventory data that emit 
EtO and we have already estimated impacts for these flares to comply 
with Control

[[Page 7960]]

Option 1, we do not expect any additional costs from this proposed GACT 
standard.
7. Standards for Fenceline Monitoring EtO
    As discussed in section IV.C.7 of this preamble as well, fenceline 
monitoring is the practice by which monitors are placed around the 
perimeter of a facility to measure the concentration of certain 
pollutants. When required in conjunction with root cause analysis and 
corrective action, fenceline monitoring can reduce uncertainties 
associated with fugitive emissions estimation and characterization. 
This section of the preamble is limited to the discussion of fenceline 
monitoring for EtO. Section IV.C.7 of this preamble provides details on 
why we are not proposing fenceline monitoring for CMPUs using, 
producing, storing, or emitting other table 1 HAP.
    In the promulgated amendments to the HON, the EPA finalized a new 
EPA method (EPA Method 327 of 40 CFR part 63, appendix A) to monitor 
the concentration of EtO at facility fenceline locations. EPA Method 
327 provides procedures for canister sampling and analysis for 
measuring trace levels of targeted VOC (including organic HAP) in air. 
EPA Method 327 collects ambient air samples using specially prepared 
and pre-cleaned evacuated stainless-steel canisters. For analysis, the 
method specifies procedures for concentrating the target VOC (i.e., 
EtO) in a known volume of air drawn from the canister, desorbing the 
target VOC from the preconcentrator, and determining the concentration 
of the target VOC using a gas chromatograph-mass spectrometer. The EPA 
continues to investigate cost-effective monitoring methods and 
technologies that could offer improved sensitivity, improved time 
resolution, or increased time integration.
    As part of the HON, fenceline monitoring in combination with root 
cause analysis and corrective action was required for affected sources 
using, producing, storing, or emitting EtO. The program requires a 
cannister sample to be collected in accordance with EPA Method 327 for 
one 24-hour period every five days. This monitoring frequency is 
necessary to ensure that all onsite processes are monitored regularly 
while maintaining the cost effectiveness of implementing a canister 
monitoring network. A sampling frequency of every 5 days also ensures 
that the annual average concentration derived from the fenceline data 
are indicative of the actual average emissions from the site by 
reducing the possibility that sampling occurs only during emission 
spikes. Once samples are analyzed, the lowest sample value for EtO is 
subtracted from the highest sample value for EtO, generating a 
[Delta]c. This approach subtracts the estimated contributions from 
background emissions that do not originate from the facility. The owner 
or operator would average the [Delta]c for the most recent year of 
samples (73 sampling periods) to calculate an annual average [Delta]c 
on a rolling basis (i.e., calculate a new annual average [Delta]c every 
5 days using data from the most recent 73 sampling periods). The owner 
or operator would compare this rolling annual average [Delta]c against 
the concentration action level for EtO. The action level for EtO 
established as part of the HON is 0.2 micrograms per cubic meter 
([micro]g/m\3\) based on three times the representative detection limit 
(RDL) for EtO.
    If the annual average [Delta]c for a facility exceeds the action 
level, then root cause analysis and corrective action must be 
performed. Root cause analysis is an assessment conducted through a 
process of investigation to determine the primary underlying cause and 
other contributing causes of an exceedance of the action level. If the 
underlying causes of the action level exceedance are deemed to be from 
sources under the control of the owner or operator, the owner or 
operator is required to take corrective action to address the 
underlying cause of the exceedance and to bring the annual average 
[Delta]c back below the action level as expeditiously as possible. 
Completion of the root cause analysis and initial corrective action is 
required within 45 days of determining that the annual average [Delta]c 
exceeded the action level. If the owner or operator requires longer 
than 45 days to implement the corrective actions identified by the root 
cause analysis, the owner or operator is required to submit a 
corrective action plan no later than 60 days after completion of the 
root cause analysis.
    After completion of the initial corrective action, if the [Delta]c 
for the next three sampling periods for samples collected by EPA Method 
327 are below the action level, then the corrective action is assumed 
to have fixed the problem, and the owner and/or operator has no further 
obligation for additional corrective action. However, if the [Delta]c 
for the subsequent sampling periods after initial corrective action is 
greater than the action level, then the owner or operator must submit a 
corrective action plan and schedule for implementing design, operation, 
and maintenance changes to eliminate as quickly as possible and prevent 
recurrence of the primary cause and other contributing causes to the 
exceedance of the action level, to reduce annual average concentrations 
below the action level. If the owner or operator cannot determine the 
root cause of the exceedance within 30 days of determining that there 
was an exceedance of an action level, the proposed revisions require 
use of real-time sampling techniques (e.g., mobile gas chromatographs) 
to determine the root cause of the exceedance. While the action 
level(s) are based on annual average concentrations, once an action 
level is exceeded, each sampling period that exceeds the action level 
contributes to the [Delta]c remaining above the action level. An 
investigation must be conducted to determine the root cause and, if 
appropriate, to correct the root cause expeditiously to bring the 
annual average [Delta]c below the action level.
    Given the similarities between certain sources subject to the HON 
and CMAS CMPUs in EtO service, the threat of adverse effect on human 
health (as discussed in section II.A.1 of this preamble), and the 
observed inconsistency between modeling the fenceline concentrations of 
sources subject to the HON and actual fenceline concentration 
measurements,\28\ we assessed whether the same fenceline monitoring 
program was appropriate. We find fenceline monitoring via EPA Method 
327 to be ``generally available'' per the language of CAA section 
112(d)(5). Canister measurements for EtO have been possible since 1999 
via Method TO-15. While EPA Method 327 was finalized in May 2024 as 
part of the revisions to the HON (see 89 FR 42932); many of the 
practices, media, and instrumentation necessary for the analysis have 
been available since 2019 via an update to Method TO-15, Method TO-15A. 
EPA Method 327 codifies the best practices of Method TO-15A and 
mandates enhanced QA/QC approaches, such as a regular validation of the 
sampling media, site verification for the sampling, defined sample 
holding times, and ongoing field and spike blanks to evaluate 
performance. In addition, development of logistics and practices to 
support EPA Method 327 laboratory analysis will also be occurring 
alongside other, similar chemical manufacturing rulemakings. Lastly, as 
a practice, placing monitors around a facility to measure fugitive 
emissions has been required as part of

[[Page 7961]]

the Petroleum Refineries NESHAP (40 CFR part 63, subpart CC) since 
2018. Given the monitoring technology has been available for several 
decades and the methodology, while new, is an adjustment to a well 
understood 2019 method to ensure the validity of samples, we find EPA 
Method 327 to be ``generally available'' per the language of CAA 
section 112(d)(5). Both root cause analysis and corrective action 
already take place at facilities where large emission events occur. 
When an event occurs, the source will be determined and will be fixed. 
This is a regular part of operation and thus root cause analysis and 
corrective action are already available to every facility potentially 
impacted by the proposed fenceline monitoring management practice.
---------------------------------------------------------------------------

    \28\ EPA, 2023. Clean Air Act Section 112(d)(6) Technology 
Review for Fenceline Monitoring located in the SOCMI Source Category 
that are Associated with Processes Subject to HON and for Fenceline 
Monitoring that are Associated with Processes Subject to Group I 
Polymers and Resins NESHAP. EPA Docket ID No. EPA-HQ-OAR-2022-0730-
0091.
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    For the 33 facilities within the proposed source category, Chemical 
Manufacturing with Ethylene Oxide, EtO is ubiquitous and should be 
present in most streams associated with CMPUs in EtO service. As such, 
for these facilities, EtO can act as a surrogate pollutant to track and 
limit overall fugitive emissions of HAP at the fenceline. Therefore, 
using information from the CMAS emissions inventory (see section II.C.2 
of this preamble), we modeled what the fenceline concentrations for EtO 
would be for the 33 facilities identified to use, produce, store, or 
emit EtO based on whole facility emissions when considering those 
options proposed in sections IV.A.1 through IV.A.6 and section IV.A.8. 
The modeling showed that 32 of the 33 facilities had EtO fenceline 
concentrations at or below 0.2 [micro]g/m\3\, three times the RDL for 
EtO and the action level finalized as part of the HON. In addition, the 
one facility that was modeled to have a fenceline concentration greater 
than 0.2 [micro]g/m\3\ was identified as having a high degree of 
uncertainty associated with their emissions inventory as the facility 
only reported a single EtO record. In addition to revisions made to the 
baseline data, post-control emission reductions were established using 
state permitting and approximate impacts (for additional details on 
facility specific adjustments to emissions, see appendix 1 of the 
document entitled Risk Assessment for the Chemical Manufacturing Area 
Source (CMAS) Category in Support of the 2025 Technology Review for the 
Proposed Rule, available in the docket for this rulemaking). While 
exact emission reductions cannot be calculated due to the nature of 
fugitive emissions and uniqueness of each root cause analysis and 
corrective action performed as part of the fenceline monitoring 
program, we anticipate there will be EtO emission reductions associated 
with fenceline monitoring.
    The cost of the fenceline monitoring program is shown in table 7 of 
this preamble. We estimated the cost required for each impacted 
facility to build the necessary housing for the cannisters, purchase 
and install the cannisters, and continually monitor the fenceline 
concentration of EtO. See the document titled Clean Air Act Section 
112(d)(5) GACT Standard Analysis and CAA Section 112(d)(6) Technology 
Review for Fenceline Monitoring for Chemical Manufacturing Process 
Units Associated with the Chemical Manufacturing Area Sources NESHAP, 
which is available in the docket for this rulemaking, for additional 
details on the analysis and methodology associated with these costs.
    Based on the costs and need to monitor for fugitive emissions of 
EtO, we are proposing to revise the CMAS NESHAP to require fenceline 
monitoring for EtO if a new or existing affected source uses, produces, 
stores, or emits EtO pursuant to CAA section 112(d)(5).
    We are soliciting comment on the proposed fenceline monitoring 
program and the supporting analysis including the costs, benefits, and 
underlying assumptions.

 Table 7--Nationwide Cost Impacts for Requiring Fenceline Monitoring for
    CMAS That Use, Produce, Store, or Emit EtO at CMAS Facilities \1\
------------------------------------------------------------------------
                                                              Total
  Number of CMAS facilities impacted     Total capital      annualized
                                         investment ($)    costs ($/yr)
------------------------------------------------------------------------
33....................................         488,000       20,990,000
------------------------------------------------------------------------
\1\ Facilities that would either become subject to the CMAS NESHAP if
  EtO is added to table 1 to 40 CFR part 63, subpart VVVVVV, as
  proposed, or are already subject to the CMAS NESHAP and emits EtO.

    We are proposing to require fenceline monitoring for CMAS using, 
producing, storing, or emitting EtO at 40 CFR 63.11495(a)(8) by 
reference to the HON (40 CFR 63.184).
    A primary requirement for a fenceline monitoring system is that it 
provides adequate spatial coverage for determination of representative 
pollutant concentrations at the boundary of the facility. In an ideal 
scenario, owners or operators would place fenceline monitors so that 
any fugitive plume originating within the facility would have a high 
probability of intersecting one or more monitors, regardless of wind 
direction. Therefore, by referencing 40 CFR 63.184(b)(3) via 40 CFR 
63.11495(a)(8) we propose that each facility would place eight 
canisters evenly spaced on the monitoring perimeter. The monitoring 
perimeter may be the facility fenceline or may be inside the facility 
fenceline, provided all sources of EtO are contained within the 
perimeter. The EPA is also proposing to require that facilities move 
the canister sampling locations with alternating sampling periods to 
ensure complete spatial coverage of the facility. For facilities with 
perimeters less than or equal to 5,000 meters, all eight sampling 
points would be monitored during each sampling period. For facilities 
with perimeters greater than 5,000 meters but less than or equal to 
10,000 meters, 16 sampling points would be required; for facilities 
with perimeters greater than 10,000 meters, 24 sampling points would be 
required. For facilities with EtO emission sources that are not 
contained within one contiguous area, the EPA is proposing monitoring 
of these secondary areas as well, with the size of the secondary area 
dictating the number of canisters.
    In addition, we are proposing to allow the subtraction of offsite 
interfering sources (as they are not within the control of the owner or 
operator) through site-specific monitoring plans, but we are not 
providing this option for onsite, non-source category emissions. We 
based the action level on facility-wide emissions; therefore, we 
considered these non-source category sources in its development. 
Applying the fenceline standard to the whole facility will also limit 
emissions of EtO from all sources and provide more certainty in 
decisions being made as to whether the entire facility emissions align 
with what is expected from the EPA's analysis. It will also provide 
assurance to fenceline communities that emission reductions are 
achieved and maintained.
    The EPA is also proposing, by reference to the HON at 40 CFR 
63.182(e), that owners or operators report fenceline data on a 
quarterly basis. Each report would contain the results for each sample 
where the field portion of sampling is completed by the end of the 
quarter, as well as for associated field and method blanks (i.e., each 
report would contain data for 18 canister sampling periods). Owners or 
operators would report these data electronically to the EPA within 45 
days after the end of each quarterly period. See section IV.D.1 of this 
preamble for further discussion on electronic reporting and section 
IV.E.1 of this preamble for further discussion on the compliance dates 
being proposed.

[[Page 7962]]

8. PRDs in EtO Service
    The CMAS NESHAP regulates PRDs through equipment leak management 
practices. These practices require owners and operators to conduct 
quarterly sensory-based inspections (using sight, sound, or smell) to 
ensure that equipment (including PRDs) is ``sound and free of leaks.'' 
However, these provisions do not apply to an emissions release from a 
PRD (see section IV.B.2 of this preamble for more detail).
    The EPA is proposing an LDAR program (using EPA Method 21) for all 
equipment in organic HAP service (see section IV.C.1 of this preamble). 
Additionally, management practices for PRD releases are being proposed 
(see section IV.B.2 of the preamble). A 2023 study at an area source 
chemical manufacturing facility indicated that EtO PRD releases because 
of railcar switchover contributed to elevated levels of EtO at the 
facility's fenceline.\29\ If those emissions had not been released to 
the atmosphere, the emissions would be characterized as process vent 
emissions and potentially subject to the proposed provisions in section 
IV.A.3 of this preamble. Given that neither the equipment leaks nor the 
process vents analyses account for the episodic nature of PRD releases 
and the observed need via the 2023 study, it is reasonable to consider 
a management practice regulating PRDs in EtO service.
---------------------------------------------------------------------------

    \29\ The study, Assessment of chemical facility ethylene oxide 
emissions using mobile and multipoint monitoring, focused on 
measuring the concentration of EtO at a chemical manufacturer's 
fenceline. Elevated levels of EtO were measured nearest sources of 
ground level fugitive emissions such as wastewater outfall and 
during periods of irregular operation via PRD releases. The complete 
study can be found and read here: https://doi.org/10.1016/j.aeaoa.2023.100214.
---------------------------------------------------------------------------

    To assess appropriate GACT standards for EtO releases from PRDs, we 
reviewed other rulemakings and identified two rules with requirements 
for PRDs ``in ethylene oxide service.'' The EPA recently added 
requirements to the MON and HON making any release event from a PRD in 
EtO service a deviation \30\ from the work practice standards for PRD 
releases (see 85 FR 49084, August 12, 2020, and 89 FR 42932, May 16, 
2024, respectively).
---------------------------------------------------------------------------

    \30\ The current HON rule text does not define or use the term 
``deviation'' and instead uses the term ``violation.'' Given that 
both the CMAS NESHAP and the MON rule text define and uses the term 
``deviation'' to describe emissions events, we believe it is more 
appropriate to continue to use the term ``deviation'' (in lieu of 
``violation'') in all of the CMAS rule text.
---------------------------------------------------------------------------

    Given these EtO specific requirements in the MON and HON for PRDs 
in EtO service, the minimal operational differences between PRDs at 
MON, SOCMI, and CMAS facilities, and to ensure that EtO is not released 
to atmosphere from a PRD, we are also proposing at 40 CFR 
63.11495(a)(7), by reference to the HON (40 CFR 63.165(e)(3)(v)(D)), 
that any release event from a PRD in EtO service at a new or existing 
affected source is a deviation of the standard. We do not expect any 
additional costs from this proposed GACT standard.

B. What are our other proposed decisions regarding GACT standards for 
CMAS, and what is the rationale for those decisions?

    In addition to the GACT standards we are proposing for certain 
emission sources that emit EtO as discussed in section IV.A of this 
preamble, we are also proposing GACT standards for pressure vessels and 
PRDs as described in sections IV.B.1 and IV.B.2 of this preamble, 
respectively. In addition, we are proposing in section IV.B.3 of this 
preamble to clarify regulatory provisions for vent control bypasses for 
closed vent systems containing bypass lines.
1. Pressure Vessels
    Pursuant to CAA section 112(d)(5), we are proposing new 
requirements for pressure vessels that are associated with processes 
subject to the CMAS NESHAP. The EPA is proposing to define pressure 
vessel at 40 CFR 63.11502(a), by reference to the HON (40 CFR 63.101), 
to mean ``a storage vessel that is used to store liquids or gases and 
is designed not to vent to the atmosphere as a result of compression of 
the vapor headspace in the pressure vessel during filling of the 
pressure vessel to its design capacity.'' To eliminate any ambiguity in 
applicability or control requirements, the EPA is also proposing at 40 
CFR 63.11502(b) to remove the exemption for ``pressure vessels designed 
to operate in excess of 204.9 kilopascals (kPa) and without emissions 
to the atmosphere'' from the definition of storage tank. This long-
standing exemption is ambiguous with respect to what ``without 
emissions to the atmosphere'' means. For example, most pressure vessels 
have relief devices that allow for venting when pressure exceeds 
setpoints. In many cases, these vents are routed to control devices; 
however, control devices are not completely effective (e.g., achieve 
95-percent control), and therefore there are emissions to the 
atmosphere from these pressure vessels, even if they are controlled. 
There are also instances where other components in pressure systems may 
allow for fugitive releases because of leaks from fittings or cooling 
systems. These events arguably are ``emissions to the atmosphere'' and 
therefore it is likely that even if the CMAS NESHAP maintained this 
exemption, owners and operators of pressure vessels would still have 
uncertainty regarding whether they were subject to substantive 
requirements. Therefore, the proposed revisions remove the ambiguity 
associated with the exemption and set new GACT standards intended to 
limit emissions to the atmosphere from pressure vessels storing organic 
HAP with capacities greater than or equal to 20,000 gallons at new and 
existing affected sources. We are proposing the same standards for 
pressure vessels of any capacity and vapor pressure storing EtO such 
that it can be considered to be a storage tank in EtO service. We are 
also clarifying in the definition of CMPU at 40 CFR 63.11494(b) that 
the collection of equipment that is part of a CMPU includes pressure 
vessels.
    We estimate a pressure vessel is located at 15 of the 247 CMAS 
facilities given that these 15 facilities reported 1,3-butadiene 
emissions from processes subject to the CMAS NESHAP, and this chemical 
is stored in pressure vessels. We excluded CMAS facilities that may 
have pressure vessels storing EtO given that we are proposing more 
stringent standards for connectors in EtO service, gas/vapor and light 
liquid valves in EtO service, and light liquid pumps in EtO service 
(see section IV.A.1 of this preamble). Using information from a 2012 
analysis that identified developments for storage vessels at chemical 
manufacturing facilities and petroleum refineries,\31\ we estimate a 
total HAP emission reduction of 2.24 tpy for all affected pressure 
vessels associated with processes subject to the CMAS NESHAP (assuming 
10 percent of all CMAS pressure vessels storing 1,3-butadiene would 
have components that leak). The nationwide capital cost for the 
proposed pressure vessel LDAR requirements for the CMAS NESHAP is about 
$3,800 and the annualized capital cost is $3,330.
---------------------------------------------------------------------------

    \31\ Randall, 2012. Memorandum from Randall, D., RTI 
International to Parsons, N., EPA/OAQPS. Survey of Control 
Technology for Storage Vessels and Analysis of Impacts for Storage 
Vessel Control Options. January 20, 2012. EPA Docket ID No. EPA-HQ-
OAR-2010-0871.
---------------------------------------------------------------------------

    Based on the costs and emission reductions, we are proposing LDAR 
requirements at 40 CFR 63.11497(f) and items 6 and 7 of table 5 to the 
CMAS NESHAP that are based on similar no-detectable emission 
requirements required for closed vent systems in most chemical sector 
NESHAP, including but not limited to the HON and MON. We

[[Page 7963]]

are proposing that these LDAR requirements for pressure vessels reflect 
GACT at new and existing affected sources. We did not identify any 
additional options beyond this for controlling emissions from pressure 
vessels. The requirements would apply to all new and existing affected 
sources and impose a standard that requires no detectable emissions at 
all times (i.e., owners and operators would be required to meet a leak 
definition of 500 ppmv at each point on the pressure vessel where total 
organic HAP could potentially be emitted); require initial and annual 
leak monitoring using EPA Method 21 of 40 CFR part 60, appendix A-7; 
and require routing organic HAP through a closed vent system to a 
control device (i.e., no releases to the atmosphere through a pressure 
vessel's PRD). These proposed LDAR requirements would also subject 
connectors in EtO service, gas/vapor or light liquid valves in EtO 
service, and light liquid pumps in EtO service to more stringent LDAR 
requirements under the proposed EtO equipment leak standards.
    See the document titled Clean Air Act Section 112(d)(5) GACT 
Standard Analysis for Pressure Vessels Associated with Processes 
Subject to the CMAS NESHAP, which is available in the docket for this 
rulemaking, for details on the assumptions and methodologies used in 
this analysis.
2. PRDs
    The CMAS NESHAP regulates PRDs through equipment leak management 
practices. These practices require owners and operators to conduct 
quarterly sensory-based inspections (using sight, sound, or smell) to 
ensure that a PRD is ``sound and free of leaks'' (see 40 CFR 
63.11495(a)(3)). These inspections typically occur when the PRD is 
seated, as PRDs are designed to open only during a pressure release 
(i.e., when the system pressure exceeds the PRD's set pressure).
    The CMAS NESHAP does not explicitly regulate atmospheric pressure 
releases, regardless of whether they are single or multiple releases 
over time. Consequently, no CMAS facility is subject to numeric 
emission limits for PRDs that vent to the atmosphere. It is impractical 
to measure emissions from PRDs that release to the atmosphere, making 
numeric emission limits inappropriate. However, the EPA has included 
work practice standards that regulate atmospheric pressure releases 
from PRDs in other chemical sector NESHAP, such as the EMACT standards 
(85 FR 40386, July 6, 2020; see 40 CFR 63.1107(h)(3)), the MON (85 FR 
49084, August 20, 2020; see 40 CFR 63.2480(e)(3)), and the HON and 
Group I Polymers and Resins Industry (P&R I) NESHAP (89 FR 42932, May 
16, 2024; see 40 CFR 63.165(e)(3)). The EPA also added PRD work 
practice standards to the petroleum refinery NESHAP for similar reasons 
(81 FR 45241, December 1, 2015; see 40 CFR 63.648(j)(3)). These PRD 
work practice standards (in all these listed NESHAP) require owners and 
operators to: (1) implement at least three prevention measures; \32\ 
(2) perform root cause analysis and corrective action if a PRD releases 
emissions directly to the atmosphere; and (3) monitor PRDs using a 
system that can identify and record the time and duration of each 
pressure release and notify operators when a pressure release occurs.
---------------------------------------------------------------------------

    \32\ Examples of prevention measures include the following: Flow 
indicators, level indicators, temperature indicators, pressure 
indicators, routine inspection and maintenance programs, operator 
training, inherently safer designs, safety instrumentation systems, 
deluge systems, and staged relief systems where the initial PRD 
discharges to a control system.
---------------------------------------------------------------------------

    We assessed whether the same PRD work practice standards, already 
included in the previously mentioned NESHAPs, represent GACT (i.e., in 
the form of management practices) for CMAS. These standards would 
regulate emissions from CMAS PRDs during a pressure release. The PRD 
work practice standards require monitoring systems that can alert an 
owner or operator when a PRD release occurs. We find this equipment to 
be ``generally available'' according to CAA section 112(d)(5). As 
noted, this type of monitoring equipment is already mandated under 
other chemical sector regulations, including the HON and the MON. Given 
its widespread use in similar chemical manufacturing facilities, we 
consider the PRD work practice standards, which include the use of 
monitoring systems capable of alerting an owner or operator when a PRD 
release occurs, to be ``generally available.''
    The cost for CMAS facilities to implement a management practice 
identical to the work practice standard in the HON and MON and install 
monitors for PRDs that vent to the atmosphere is based on the number of 
PRDs at each facility. However, we do not have actual equipment counts 
for CMAS facilities. To estimate the number of PRDs at CMAS facilities 
nationwide, we used HON-specific PRD data that was submitted in 
response to the EPA's 2022 CAA section 114 request (see section II.C.3 
of this preamble). We calculated an average of 14 atmospheric PRDs in 
organic HAP service per CMAS CMPU. Multiplying this average by the 
total CMAS processes nationwide (247, assuming one CMPU per CMAS 
facility), we estimated there are 3,458 atmospheric PRDs in organic HAP 
service nationwide. We excluded 33 facilities \33\ from this analysis 
given that we anticipate that these facilities are likely to only 
operate PRDs in EtO service that already have PRD monitoring installed. 
We used work practice costs from a 2015 memorandum \34\ on PRD impacts 
for petroleum refineries to estimate costs for implementing at least 
three prevention measures and performing root cause analysis and 
corrective action at CMAS facilities. Similarly, based on the HON-
specific PRD data from the EPA's 2022 CAA section 114 request, we 
calculated an average of three atmospheric PRDs in organic HAP service 
per CMAS CMPU that have a monitoring system installed capable of 
identifying releases and recording the time and duration of each 
pressure release. Therefore, multiplying the average of 11 (14 
atmospheric PRDs less the three that already have monitoring systems 
installed) atmospheric PRDs in organic HAP service per CMAS CMPU that 
do not have a monitoring system by the total CMAS processes nationwide 
(247, assuming one CMPU per CMAS facility), we estimated that of the 
3,458 PRDs in organic HAP service nationwide, 2,717 PRDs in organic HAP 
service nationwide vent to the atmosphere without a device or 
monitoring system capable of identifying releases and recording the 
time and duration of each pressure release. We then used PRD monitor 
costs from a 2017 memorandum \35\ on PRD options for off-site waste and 
recovery operations to estimate the costs for installing PRD monitors 
at CMAS facilities. Based on our cost assumptions, the nationwide 
capital cost for complying with the PRD work practice requirements for 
the CMAS NESHAP (in the form of management practices) is $15.9 million, 
with annualized capital costs of $4.7 million. This translates to 
approximately $64,300 in total capital investment and $19,200 in total 
annual cost per CMAS

[[Page 7964]]

facility. We are unable to estimate HAP reductions from requiring 
owners and operators to comply with these management practices because 
PRD pressure releases can occur as single or multiple events over time. 
In other words, these releases can result from system overpressure 
caused by operator error, malfunctions such as power or equipment 
failures, or other unexpected causes that necessitate immediate venting 
of gas from process equipment to prevent safety hazards or equipment 
damage; all of which are too difficult to predict. Even so, we 
anticipate that implementing these additional PRD management practices, 
along with the proposed equipment leak LDAR program for PRDs (see 
section IV.C.1 of this preamble), will achieve significantly greater 
emission reductions than the equipment leak management practices 
currently required by the CMAS NESHAP.
---------------------------------------------------------------------------

    \33\ These facilities are already subject to, or may become 
subject to, the CMAS NESHAP if EtO were to be added to table 1 to 40 
CFR part 63, subpart VVVVVV.
    \34\ EPA, 2015. Coburn, Jeff, RTI International. Pressure Relief 
Device Control Option Impacts for Final Refinery Sector Rule. July 
30, 2015. EPA Docket ID No. EPA-HQ-OAR-2010-0682.
    \35\ EPA, 2017. Carey, Angela, EPA/OAQPS. Pressure Relief Device 
Control Options and Impacts for Off-Site Waste and Recovery 
Operations (OSWRO). June 26, 2017. EPA Docket ID No. EPA-HQ-OAR-
2012-0360.
---------------------------------------------------------------------------

    As such, pursuant to CAA section 112(d)(5), we are proposing new 
requirements for PRDs that are associated with processes subject to the 
CMAS NESHAP. We are proposing PRD management practices for all new and 
existing affected sources at 40 CFR 63.11495(a)(6), by reference to the 
HON (40 CFR 63.165(e)(1) through (8)), that require owners and 
operators to: (1) operate each PRD in organic HAP gas or vapor service 
with an instrument reading of less than 500 ppm above background as 
measured by the method specified in 40 CFR 63.180(c); (2) conduct 
instrument monitoring no later than 5 calendar days after the PRD 
returns to organic HAP gas or vapor service following a pressure 
release to verify that the PRD is operating with an instrument reading 
of less than 500 ppm, or if applicable, install a replacement disk as 
soon as practicable after a pressure release, but no later than 5 
calendar days after the pressure release; (3) implement at least three 
prevention measures; (4) perform root cause analysis and corrective 
action if a PRD releases emissions directly to the atmosphere; and (5) 
monitor PRDs using a system that can identify and record the time and 
duration of each pressure release and notify operators when a pressure 
release occurs. The EPA is also proposing to define ``pressure relief 
device or valve'' at 40 CFR 63.11502(a), by reference to the HON (40 
CFR 63.101), to mean ``a valve, rupture disk, or similar device used 
only to release an unplanned, nonroutine discharge of gas from process 
equipment in order to avoid safety hazards or equipment damage. A PRD 
discharge can result from an operator error, a malfunction such as a 
power failure or equipment failure, or other unexpected cause. Such 
devices include conventional, spring-actuated relief valves, balanced 
bellows relief valves, pilot-operated relief valves, rupture disks, and 
breaking, buckling, or shearing pin devices. Devices that are actuated 
either by a pressure of less than or equal to 2.5 pounds per square 
inch gauge or by a vacuum are not pressure relief devices.'' In 
addition, the EPA is proposing to define ``pressure release'' at 40 CFR 
63.11502(a), by reference to the HON (40 CFR 63.101), to mean ``the 
emission of materials resulting from the system pressure being greater 
than the set pressure of the pressure relief device. This release can 
be one release or a series of releases over a short time period.''
    See the document titled Clean Air Act Section 112(d)(5) GACT 
Standard Analysis for Pressure Relief Devices Associated with Processes 
Subject to the CMAS NESHAP, which is available in the docket for this 
rulemaking, for details on the assumptions and methodologies used in 
this analysis. We solicit comments on the proposed management practice 
for PRDs and assumptions associated with the analysis.
3. Closed Vent System Containing Bypass Lines
    For a closed vent system containing bypass lines that can divert 
the stream away from the APCD to the atmosphere, the CMAS NESHAP 
requires the owner or operator to either: (1) install, maintain, and 
operate a continuous parametric monitoring system for flow on the 
bypass line that is capable of detecting whether a vent stream flow is 
present at least once every hour, or (2) secure the bypass line valve 
in the non-diverting position with a car-seal or a lock-and-key type 
configuration. Under option 2, the CMAS NESHAP also requires owners or 
operators to inspect the seal or closure mechanism at least once per 
month to verify the valve is maintained in the non-diverting position 
(e.g., for more details see items 1.a and 1.b of tables 2 and 3 to the 
CMAS NESHAP and items 1.b and 1.c of table 5 to the CMAS NESHAP, which 
all reference provisions in 40 CFR part 63, subpart SS that ultimately 
point to bypass monitoring requirements in 40 CFR 63.983(a)(3)). To 
expressly prohibit bypassing an APCD at affected sources, as implied by 
option 2, we are proposing that an owner or operator may not bypass the 
APCD at any time and that a bypass is a violation (see proposed 40 CFR 
63.11495(e)), and owners and operators must estimate, maintain records, 
and report the quantity of organic HAP released (see proposed 40 CFR 
63.11501(c)(10) and (d)(10)). We are proposing these revisions to 
ensure continuous compliance with the GACT standards because bypassing 
an APCD could result in a release of regulated organic HAP to the 
atmosphere that would be required to be controlled under the existing 
GACT standards in the CMAS NESHAP. We are also proposing that the use 
of a cap, blind flange, plug, or second valve on open-ended valves or 
lines (following the requirements specified in 40 CFR 60.482-6(a)(2), 
(b), and (c) or following requirements codified in another regulation 
that are the same as 40 CFR 60.482-6(a)(2), (b), and (c)) is sufficient 
to prevent a bypass. We solicit comments on these proposed revisions.
    In addition, we are proposing to remove the 40 CFR 63.107(h)(9) 
exemption for ``a gas stream exiting an analyzer'' from the definition 
of continuous process vent at 40 CFR 63.11502(b) and we are proposing 
at 40 CFR 63.11495(e) to not exempt analyzer vents from the bypass 
requirements. As such, we are proposing to require that these kinds of 
vents meet the standards applicable to process vents at all times. 
Analyzer vents, or ``onstream analyzers,'' generally refer to sampling 
systems that directly feed to an analyzer located at a process unit and 
venting is expected to be routine (continuous or daily intermittent 
venting). We also note that sampling connection systems for CMPUs will 
be required to be part of a closed loop, closed purge, or closed vent 
system under our proposed equipment leak standards (e.g., 40 CFR 
63.166(a), see section IV.C.1 of this preamble for further details). In 
these applications, the analyzer vent would not be a bypass of 
emissions subject to the requirements in 40 CFR 63.11495 through 
63.11498, rather the analyzer vent would be a process vent itself, thus 
engineering calculations would be used to determine if this vent is a 
process vent requiring control as specified in tables 2 through 4 to 
the CMAS NESHAP. In rare instances, the owner or operator may classify 
a release point on a gaseous vent system associated with a CMPU as an 
``analyzer vent''. In this case, the analyzer vent when open acts as a 
bypass line (allowing direct atmospheric release) of a process vent 
stream. These examples demonstrate that depending on the circumstance, 
an analyzer vent could be construed as a process vent or a bypass line. 
Thus, we see no reason to categorically allow use of analyzer vents to 
bypass controls required for

[[Page 7965]]

emissions subject to the requirements in 40 CFR 63.11495 through 
63.11498.

C. What are the results and proposed decisions based on our technology 
review, and what is the rationale for those decisions?

    As described in section III.B of this preamble, the technology 
review for the CMAS NESHAP focused on the identification and evaluation 
of developments in practices, processes, and control technologies that 
have occurred since the NESHAP was promulgated in 2009. In conducting 
the technology review, we reviewed various sources of information 
related to the emissions from chemical manufacturing operations and 
other relevant information such as control technologies applied, 
management practices used, processes, and monitoring approaches. 
Through searches of these data sources, we identified, evaluated, and 
considered several developments in practices, processes, or control 
technologies. As discussed below, these include developments and 
improvements that could result in the addition of emission limits, 
management practices, and other emission reduction requirements, as 
well as revised compliance assurance measures. We analyzed costs and 
emissions reductions for each emission source and determined cost-
effectiveness (annualized cost per ton of emissions reduction) on a HAP 
basis. The data, analyses, results, and proposed decisions pursuant to 
CAA section 112(d)(6) are presented for each emission source in 
sections IV.C.1 through IV.C.7 of this preamble.
    Based on this review, the EPA is proposing amendments to the CMAS 
NESHAP pursuant to CAA section 112(d)(6) that improve monitoring of 
leaks from equipment and heat exchange systems and revises the 
definition of ``metal HAP process vent.'' We are not proposing any 
changes to the CMAS NESHAP for storage tanks and wastewater based on 
our technology review given that we did not identify any cost-effective 
developments in practices, processes, or control technologies for these 
emission sources that achieve a greater HAP emission reduction beyond 
the emission reduction already required by the CMAS NESHAP.
1. Equipment Leaks
    Emissions from equipment leaks occur in the form of gases or 
liquids that escape to the atmosphere through connection points (e.g., 
threaded connectors) or through the moving parts of different 
components (e.g., agitators, compressors, PRDs, pumps, valves) and 
certain types of process equipment. Each component type has a unique 
manner in which emissions are released (e.g., connectors may leak if 
the threads become damaged or corroded or if not tightened 
sufficiently, pumps can leak at the point of contact between the moving 
shaft and stationary casing, valves can leak through the seal around 
the valve stem).
    The CMAS NESHAP requires that facilities conduct quarterly 
inspections of process vessels and equipment for each CMPU in organic 
HAP service or metal HAP service. Equipment is defined as ``each pump, 
compressor, agitator, pressure relief device, sampling connection 
system, open-ended valve or line, valve, connector, and instrumentation 
system in or associated with a CMPU.'' The inspections rely on AVO 
detection methods to determine whether process vessels and equipment 
are free of leaks. The CMAS NESHAP also allows instrument monitoring 
(i.e., use EPA Method 21 with a leak definition of 500 ppmv) in lieu of 
AVO methods; or, facilities may use EPA Method 21 to confirm the 
presence of HAP for leaks identified using AVO methods.
    To identify developments in practices, processes, and control 
technologies since the GACT standards were established, we reviewed 
subsequent regulatory efforts. After reviewing multiple regulations, we 
identified developments in LDAR program practices in the form of 
specific leak definitions and monitoring frequencies for LDAR programs 
that use EPA Method 21 monitoring that are different than those 
evaluated during the original CMAS rulemaking. We used the HON and MON 
as initial points of reference to identify developments, since these 
rules apply to major source chemical manufacturing facilities which are 
similar to CMAS facilities. The HON and MON require EPA Method 21 
monitoring for specific components at varying leak definitions (from 
500 ppmv to 10,000 ppmv) and frequencies (monthly monitoring to 
monitoring every 4 years if few leaks are identified). We also reviewed 
the Gasoline Distribution area source rule, which recently undertook a 
similar technology review for equipment leaks where the EPA finalized 
an LDAR program that requires annual monitoring using EPA Method 21 at 
a leak definition of 10,000 ppmv in lieu of only AVO methods. We used 
the Gasoline Distribution LDAR program, which requires annual 
monitoring at a leak definition of 10,000 ppmv, as the starting option 
(i.e., Control Option 1). We then considered two additional options 
that would impose more stringent requirements that would allow us to 
assess the impacts of more frequent monitoring (i.e., Control Option 2 
requiring semiannual monitoring) and a lower leak definition (i.e., 
Control Option 3 requiring a leak definition of 500 ppmv). We also 
evaluated the key component types for the LDAR programs (i.e., 
connectors, valves, pumps) and did not consider an option where 
connectors were not monitored. The following summarize the three 
equipment leak control options that we evaluated for this technology 
review: \36\
---------------------------------------------------------------------------

    \36\ Each equipment leak control option that we evaluated also 
includes the HON LDAR requirements specified in 40 CFR 63.164 for 
compressors, 40 CFR 63.166 for sampling connection systems, 40 CFR 
63.167 for open-ended valves or lines, 40 CFR 63.169 for equipment 
in heavy liquid service, 40 CFR 63.173 for agitators in G/V or LL 
service.
---------------------------------------------------------------------------

     Control Option 1 (for connectors in gas and vapor (G/V) 
service or in light liquid (LL) service, valves in G/V or LL service, 
and pumps in LL service): monitor all components annually using EPA 
Method 21 and a leak definition of 10,000 ppmv.
     Control Option 2 (for connectors in G/V or LL service, 
valves in G/V or LL service, and pumps in LL service): monitor all 
components semiannually using EPA Method 21 and a leak definition of 
10,000 ppmv.
     Control Option 3 (for connectors in G/V or LL service, 
valves in G/V or LL service, and pumps in LL service): monitor all 
components annually using EPA Method 21 and a leak definition of 500 
ppmv.
    To estimate the costs and emission reductions, we assumed that 247 
CMAS facilities currently follow the CMAS requirement of performing 
quarterly AVO inspections and are impacted by this technology review. 
For simplicity, we excluded 4 other CMAS facilities from our analysis 
that may have equipment leaks in EtO service; and instead, we included 
them in our GACT analysis discussed in section IV.A.1 of this preamble. 
To get the nationwide impacts of each Control Option, we estimated the 
cost and reductions for a model CMAS facility to implement each of the 
three control options and multiplied the model facility results by 247. 
The memorandum 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, which is 
available in the docket for this rulemaking, presents

[[Page 7966]]

details on the assumptions and methodologies used in this analysis.
    Table 8 of this preamble presents the nationwide impacts for 
requiring owners and operators to perform EPA Method 21 monitoring in 
accordance with Control Options 1-3. Based on the costs and emission 
reductions, we are proposing to revise the CMAS NESHAP for equipment in 
HAP service to reflect Control Option 1 pursuant to CAA section 
112(d)(6). Control Options 2 and 3 have incremental costs and emission 
reductions (i.e., incremental to Control Option 1) that are not cost 
effective and we are not proposing to revise the CMAS NESHAP to reflect 
either of these options.

                 Table 8--Nationwide Emissions Reductions and Cost Impacts of Control Options 1-3 for Requiring EPA Method 21 Monitoring for Equipment Leaks at CMAS Facilities
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                                                                                                        HAP
                                                                                                                                                                                    incremental
                                                                                       Total           Total                                         HAP cost        HAP cost          cost
                                                                   Total capital    annualized      annualized     VOC emission    HAP emission    effectiveness   effectiveness   effectiveness
                         Control option                           investment ($)     costs w/o      costs with      reductions      reductions     w/o recovery    with recovery   with recovery
                                                                                     recovery        recovery          (tpy)           (tpy)        credits ($/     credits ($/    credits (from
                                                                                  credits ($/yr)  credits ($/yr)                                       ton)            ton)        option 1) ($/
                                                                                                                                                                                       ton)
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
1...............................................................       2,499,600       2,220,500         862,000           1,510             151          14,700           5,700
2...............................................................       2,499,600       3,109,700       1,516,600           1,772             177          17,600           8,600          25,000
3...............................................................       2,499,600       3,465,400       1,968,600           1,662             166          20,900          11,800          72,700
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

    We are proposing Control Option 1 for equipment leaks at 40 CFR 
63.11495(a)(6). To effectively incorporate Control Option 1 into the 
CMAS NESHAP, we specify at proposed 40 CFR 63.11495(a)(6) that owners 
and operators of new and existing affected sources with equipment in 
organic HAP service must conduct annual leak detection monitoring of 
all pumps in light liquid service, valves in gas/vapor service and in 
light liquid service, and connectors in gas/vapor service and in light 
liquid service by the method specified in 40 CFR 63.180(b)(1) through 
(3), with certain exceptions (e.g., pumps, valves, and connectors that 
are unsafe to monitor may be exempt). We also specify at proposed 40 
CFR 63.11495(a)(6) that a leak from any of these types of equipment is 
detected if the instrument reading equals or exceeds 10,000 ppmv and a 
first attempt at repair must be made no later than 5 calendar days 
after a leak is detected. Also, we are proposing that equipment must be 
repaired as soon as practicable, but no later than 15 calendar days 
after the leak is detected, except as allowed in the HON for delay of 
repair at 40 CFR 63.171. Additionally, we are proposing at 40 CFR 
63.11495(a)(6) the HON LDAR requirements for compressors (i.e., 40 CFR 
63.164), sampling connection systems (i.e., 40 CFR 63.166), open-ended 
valves or lines (i.e., 40 CFR 63.167), equipment in heavy liquid 
service (i.e., 40 CFR 63.169), and agitators in G/V or LL service 
(i.e., 40 CFR 63.173). We note that we are also proposing the HON LDAR 
requirements for PRDs (i.e., 40 CFR 63.165) which are discussed in 
section IV.B.2 of this preamble, and the HON fenceline monitoring 
requirements (i.e., 40 CFR 63.184) which are discussed in sections 
IV.A.7 and IV.C.7 of this preamble, respectively.
2. Heat Exchange Systems
    Heat exchangers are devices or collections of devices used to 
transfer heat from process fluids to another process fluid (typically 
water) without intentional direct contact of the process fluid with the 
cooling fluid (i.e., non-contact heat exchanger). There are two types 
of heat exchange systems: closed-loop recirculation systems and once-
through systems. Closed-loop recirculation systems use a cooling tower 
to cool the heated water leaving the heat exchanger and then return the 
newly cooled water to the heat exchanger for reuse. Once-through 
systems typically use surface freshwater (e.g., from a nearby river) as 
the influent cooling fluid to the heat exchangers, and the heated water 
leaving the system is then discharged from the facility. At times, the 
internal tubing material of a heat exchanger can corrode or crack, 
allowing some process fluids to mix or become entrained with the 
cooling water. Pollutants in the process fluids may subsequently be 
released from the cooling water into the atmosphere when the water is 
exposed to air (e.g., in a cooling tower for closed-loop systems or 
trenches/ponds in a once-through system).
    The CMAS NESHAP at 40 CFR 63.11502(a), by reference to the HON (40 
CFR 63.101), defines a heat exchange system as ``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).'' Pursuant to the recent 
technology review for the HON (see 79 FR 25080, May 16, 2024), the 
definition also clarifies that: (1) For closed-loop recirculation 
systems, the heat exchange system consists of a cooling tower, all CMPU 
heat exchangers that are in organic HAP service serviced by that 
cooling tower, and all water lines to and from these process unit heat 
exchangers; (2) for once-through systems, the heat exchange system 
consists of all heat exchangers that are in organic HAP service, 
servicing an individual CMPU and all water lines to and from these heat 
exchangers; (3) sample coolers or pump seal coolers are not considered 
heat exchangers and are not part of the heat exchange system; and (4) 
intentional direct contact with process fluids results in the formation 
of a wastewater.
    The current CMAS NESHAP requirements for heat exchange systems at 
40 CFR 63.11499, by reference to the HON (40 CFR 63.104), includes an 
LDAR program for owners or operators of certain heat exchange systems 
(i.e., those not meeting one or more of the conditions in 40 CFR 
63.104(a)) with a cooling water flow rate equal to or greater than 
8,000 gpm. The LDAR program specifies that owners or operators must 
monitor heat exchange systems for leaks of process fluids into cooling 
water and take actions to repair detected leaks within 45 days; and 
owners or operators may delay the repair of leaks if they meet the 
applicable criteria in 40 CFR 63.104. The CMAS NESHAP allows owners or 
operators to use any method listed in 40 CFR part 136 to sample cooling 
water for leaks for the HAP listed in table 4 to 40 CFR part 63, 
subpart F (for recirculating systems) and table 9 to 40 CFR part 63, 
subpart G (for once-through systems) (and other

[[Page 7967]]

representative substances such as total organic compounds (TOC) or VOC 
that can indicate the presence of a leak can also be used). A leak in 
the heat exchange system is detected if the exit mean concentration of 
HAP (or other representative substance) in the cooling water is at 
least 1 ppmw or 10 percent greater than (using a one-sided statistical 
procedure at the 0.05 level of significance) the entrance mean 
concentration of HAP (or other representative substance) in the cooling 
water. Furthermore, the CMAS NESHAP allows owners or operators to 
monitor for leaks using a surrogate indicator (e.g., ion-specific 
electrode monitoring, pH, conductivity), provided that certain criteria 
in 40 CFR 63.104(c) are met. The CMAS NESHAP requires quarterly 
monitoring for heat exchange systems. The leak monitoring frequencies 
are the same whether water sampling and analysis or surrogate 
monitoring is used to identify leaks.
    For heat exchange systems at CMAS CMPUs with a cooling water flow 
rate less than 8,000 gpm that are not meeting one or more of the 
conditions in 40 CFR 63.104(a), owners and operators must develop and 
operate in accordance with a heat exchange system inspection plan that 
describes the inspections to be performed at least once per quarter. 
Inspections must provide evidence of hydrocarbons in the cooling water 
and may include checks for visible floating hydrocarbon on the water, 
hydrocarbon odor, discolored water, and/or chemical addition rates. 
Owners and operators of these heat exchange systems must also perform 
repairs to eliminate the leak within 45 calendar days after indications 
of the leak are identified but may delay the repair if a reason is 
documented in the next semiannual compliance report. As an alternative 
to the requirements described in this paragraph, owners and operators 
of heat exchange systems at CMAS CMPUs with a cooling water flow rate 
less than 8,000 gpm can choose to comply with the LDAR monitoring 
options specified for heat exchange systems with a cooling water flow 
rate equal to or greater than 8,000 gpm.
    As part of our technology review, we reviewed the criteria in 40 
CFR 63.11495(b) and 40 CFR 63.11499(a) (i.e., the reference to the 
exemptions listed in the HON at 40 CFR 63.104(a)), to see if these 
exemptions were still reasonable to maintain. We identified two 
criteria in 40 CFR 63.104 dealing with once-through heat exchange 
systems meeting certain NPDES permit conditions (i.e., 40 CFR 
63.104(a)(3) and (4)) that warranted further assessment. Once-through 
heat exchange systems typically have systems open to the air (e.g., 
open sewer lines, trenches, and ponds) that are used to transport used 
cooling water to a discharge point (e.g., an outfall) of a facility. 
This cooling water can also be mixed with other sources of water (e.g., 
cooling water used in once-through heat exchange systems in non-CMAS 
processes, stormwater, treated wastewater, etc.) in sewers, trenches, 
and ponds prior to discharge from the plant. If this point of discharge 
from the plant is into a ``water of the United States,'' the facility 
is required to have a NPDES permit and to meet certain pollutant 
discharge limits. In reviewing the requirements of 40 CFR 63.104(a)(3), 
we find that there is a clear disconnect between having a NPDES permit 
that meets certain allowable discharge limits (i.e., 1 ppmw or less 
above influent concentration, or 10 percent or less above influent 
concentration, whichever is greater) at the discharge point of a 
facility (e.g., outfall) versus being able to adequately identify a 
leak from a once-through heat exchange system given that these systems 
are open to the atmosphere prior to this discharge point and, 
therefore, any volatile HAP leaking from a once-through heat exchange 
system would likely be emitted to the atmosphere prior to the NPDES 
outfall. Similarly, while the requirements of 40 CFR 63.104(a)(4) allow 
facilities with once-through heat exchange systems that have certain 
requirements (i.e., the requirements of 40 CFR 63.104(a)(3) and (4)) 
incorporated into their NPDES permit to not comply with the 
requirements of 40 CFR 63.104(b) and (c), we find this exemption to be 
problematic. Specifically, the NPDES requirements at 40 CFR 
63.104(a)(4) lack the specificity of where a sample must be taken to 
adequately find and quantify a leak from a once-through heat exchange 
system (e.g., just prior to the outfall from the plant versus from the 
exit of the once-through heat exchange system prior to being open to 
atmosphere), what concentration and/or mass emissions rate constitutes 
a leak that must be fixed, how quickly a leak must be fixed, what 
pollutants must be adequately accounted for, and what test method(s)/
surrogates facilities are allowed. As such, we find 40 CFR 63.104(a)(4) 
to be inadequate in terms of being able to detect and repair leaks that 
are at least as equivalent to those that would be identified if once-
through heat exchange systems were complying with 40 CFR 63.104(b) or 
(c) instead. Therefore, for purposes of demonstrating continuous 
compliance with the underlying GACT standard, we are proposing at 40 
CFR 63.11495(b) and 40 CFR 63.11499(d) and (e) to remove the exemptions 
for once-through heat exchange systems meeting certain NPDES permit 
conditions at 40 CFR 63.104(a)(3) and (4) and to instead require 
facilities to monitor the cooling water for the presence of leaks.
    Our technology review also identified one development in LDAR 
practices and processes for heat exchange systems: the use of the 
Modified El Paso Method \37\ to monitor for leaks. The EPA identified 
the Modified El Paso Method, which is included in the HON, MON, EMACT 
standards, the Petroleum Refinery Sector rule, and in our review of the 
RACT/BACT/LAER clearinghouse database. The Texas Commission on 
Environmental Quality (TCEQ) also requires the method for facilities 
complying with TCEQ's highly reactive volatile organic compound (HRVOC) 
rule (i.e., 30 Texas Administrative Code Chapter 115, Subchapter H, 
Division 3). The Modified El Paso Method measures a larger number of 
compounds than the current methods required in the CMAS NESHAP and is 
more effective in identifying leaks. For LDAR programs applied to heat 
exchange systems, the compliance monitoring option, leak definition, 
and frequency of monitoring for leaks are all important considerations 
affecting emission reductions by identifying when there is a leak and 
when to take corrective actions to repair the leak. Therefore, we 
evaluated the Modified El Paso Method for use at CMAS facilities as 
described below, including an assessment of appropriate leak 
definitions and monitoring frequencies.
---------------------------------------------------------------------------

    \37\ 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 VOC using an FID analyzer. The method is 
described in detail in appendix P of the TCEQ's Sampling Procedures 
Manual: The Air Stripping Method (Modified El Paso Method) for 
Determination of Volatile Organic Compound (VOC) Emissions from 
Water Sources. Appendix P is included in the docket for this 
rulemaking.
---------------------------------------------------------------------------

    To identify an appropriate Modified El Paso Method leak definition 
for facilities subject to the CMAS NESHAP, we identified five rules 
(i.e., TCEQ HRVOC rule, the HON, the MON, the EMACT standards, and the 
Petroleum Refinery Sector rule) all of which incorporate this 
monitoring method and have leak definitions corresponding to the use of 
this methodology. We also reviewed data submitted in response to a CAA 
section 114 request for the Ethylene Production RTR where facilities 
performed sampling using the Modified El Paso Method.
    The TCEQ HRVOC rule, the HON, the MON, EMACT standards, and the

[[Page 7968]]

Petroleum Refinery Sector rule have leak definitions of total 
strippable hydrocarbon concentration (as methane) in the stripping gas 
ranging from 3.1 ppmv to 6.2 ppmv. In addition, sources subject to the 
HON, the MON, EMACT standards, or the Petroleum Refinery Sector rule 
must repair a leak no later than 45 days after first identifying the 
leak, and also may not delay the repair of leaks for more than 30 days 
where, during subsequent monitoring, owners or operators find a total 
strippable hydrocarbon concentration (as methane) in the stripping gas 
of 62 ppmv or higher. In reviewing the Ethylene Production RTR CAA 
section 114 data, we identified a clear delineation in the hydrocarbon 
mass emissions data at 6.1 ppmv of total strippable hydrocarbon (as 
methane) in the stripping gas. Taking into account the range of 
actionable leak definitions in use by other rules that require use of 
the Modified El Paso Method currently (i.e., 3.1 ppmv to 6.2 ppmv of 
total strippable hydrocarbon (as methane) in the stripping gas), and 
the magnitude of emissions for leaks as a result of total strippable 
hydrocarbon (as methane) in the stripping gas above 6.1 ppmv, we chose 
to evaluate a leak definition at the upper end of identified actionable 
leak definitions in our analysis. Thus, we evaluated the Modified El 
Paso Method leak definition of 6.2 ppmv of total strippable hydrocarbon 
concentration (as methane) in the stripping gas for both new and 
existing heat exchange systems, along with the requirement to repair a 
leak no later than 45 days after first identifying the leak, and not 
allowing delay of repair of leaks for more than 30 days where, during 
subsequent monitoring, a total strippable hydrocarbon concentration (as 
methane) in the stripping gas of 62 ppmv or higher is found.
    We also considered more stringent monitoring frequencies. Both the 
Petroleum Refinery Sector rule, which includes monthly monitoring for 
existing sources under certain circumstances, and the TCEQ HRVOC rule, 
which includes continuous monitoring provisions for existing and new 
sources, have more stringent monitoring frequencies.
    Based on this technology review, we identified the following two 
Control Options as developments in practices for heat exchanger systems 
at CMAS facilities:
     Control Option 1 (for heat exchange systems with a cooling 
water flow rate equal to or greater than 8,000 gpm): quarterly 
monitoring with the Modified El Paso Method, using a leak action level 
defined as a total strippable hydrocarbon concentration (as methane) in 
the stripping gas of 6.2 ppmv (with the requirement to repair a leak no 
later than 45 days after first identifying the leak, and allow delay of 
repair up to 120 days except no more than 30 days where a total 
strippable hydrocarbon concentration (as methane) in the stripping gas 
of 62 ppmv or higher is found). This option would also require re-
monitoring at the monitoring location where the leak was identified to 
ensure that any leaks found are fixed.
     Control Option 2: same as Control Option 1, except monthly 
monitoring with the Modified El Paso Method instead of quarterly 
monitoring.
    We then estimated the impacts of these Control Options. Using 
information from the original CMAS rulemaking,\38\ we estimated 51 of 
247 CMAS facilities would be affected by Control Options 1 and 2; and 
we assumed these facilities already conduct water sampling. For 
simplicity, we excluded 4 other CMAS facilities from our analysis that 
may have a heat exchange system in EtO service; and instead, we 
included them in our GACT analysis discussed in section IV.A.2 of this 
preamble. As part of our analysis, we also assumed all facilities 
monitoring quarterly for two or less heat exchange systems would elect 
to contract out the Modified El Paso monitoring (instead of purchasing 
a stripping column and FID analyzer and performing the monitoring in-
house); however, facilities monitoring monthly would elect to purchase 
a stripping column and FID analyzer and perform in-house El Paso 
monitoring due to logistics. In addition, we assumed repairs could be 
performed by plugging a specific heat exchanger tube, and if a heat 
exchanger is leaking to the extent that it needs to be replaced, then 
it is effectively at the end of its useful life. Therefore, we 
determined that the cost of replacing a heat exchanger is an 
operational cost that would be incurred by the facility because of 
routine maintenance and equipment replacement, and it is not 
attributable to the Control Options.
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    \38\ EPA, 2008. Control Options and Impacts for Cooling Tower 
Control Measures Chemical Manufacturing Area Source Standards. 
September 5, 2008. Docket ID No. EPA-HQ-OAR-2008-0334-0003; and EPA, 
2009. Update to the Control Options and Impacts for Heat Exchange 
System Control Measures for Promulgation Chemical Manufacturing Area 
Source Standards. May 5, 2009. Docket ID No. EPA-HQ-OAR-2008-0334-
0081.
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    Table 9 of this preamble presents the nationwide impacts for 
requiring owners and operators to use the Modified El Paso Method and 
repair leaks of total strippable hydrocarbon concentration (as methane) 
in accordance to Control Options 1 and 2. See the document titled Clean 
Air Act Section 112(d)(5) GACT Standard Analysis for Heat Exchange 
Systems that Emit Ethylene Oxide and Section 112(d)(6) Technology 
Review for Heat Exchange Systems Associated with Chemical Manufacturing 
Process Units at Area Sources Subject to the CMAS NESHAP, which is 
available in the docket for this rulemaking, for details on the 
assumptions and methodologies used in this analysis. Based on the costs 
and emission reductions for the identified Control Options, we are 
proposing to revise the CMAS NESHAP for heat exchange systems to 
reflect Control Option 1 pursuant to CAA section 112(d)(6).

Table 9--Nationwide Emissions Reductions and Cost Impacts of Control Options 1 and 2 for Requiring the Modified El Paso Method for Heat Exchange Systems
                                                                   at CMAS Facilities
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                           Total                                                             Total
                                                        annualized     VOC emission    HAP emission       HAP cost        annualized        HAP cost
           Control option              Total capital     costs w/o      reductions      reductions    effectiveness w/    costs with      effectiveness
                                      investment ($)     recovery          (tpy)           (tpy)         o recovery        recovery       with recovery
                                                      credits ($/yr)                                   credits ($/ton)  credits ($/yr)   credits ($/ton)
--------------------------------------------------------------------------------------------------------------------------------------------------------
1...................................               0          57,100            44.6            4.46            12,800          16,900             3,800
2...................................       1,046,400         214,200            46.1            4.61            46,500         172,700            37,500
--------------------------------------------------------------------------------------------------------------------------------------------------------


[[Page 7969]]

    We are proposing Control Option 1 at 40 CFR 63.11499(d) and item 
1.c of table 8 to the CMAS NESHAP, by reference to the HON (40 CFR 
63.104(a) and (f) through (l)), to specify quarterly monitoring for 
existing and new heat exchange systems (after an initial 6 months of 
monthly monitoring) 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. Owners and operators of new and 
existing affected sources would be required to repair the leak to 
reduce the concentration or mass emissions rate to below the leak 
action level as soon as practicable, but no later than 45 days after 
identifying the leak. We are also proposing at 40 CFR 63.11499(d) and 
item 1.c of table 8 to the CMAS NESHAP, by reference to the HON, a 
delay of repair action level of total strippable hydrocarbon 
concentration (as methane) in the stripping gas of 62 ppmv, 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). This would 
apply to both monitoring heat exchange systems and individual heat 
exchangers by replacing the use of any 40 CFR part 136 water sampling 
method with the Modified El Paso Method and removing the option that 
allows for use of a surrogate indicator of leaks. We are also proposing 
at 40 CFR 63.11499(d) and item 1.c of table 8 to the CMAS NESHAP, by 
reference to the HON, that repair include re-monitoring at the 
monitoring location where a leak is identified to ensure that any leaks 
found are fixed. We are proposing that none of these proposed 
requirements would apply to heat exchange systems that have a maximum 
cooling water flow rate of less than 8,000 gallons per minute because 
owners and operators of smaller heat exchange systems would be 
disproportionally affected and forced to repair leaks with a much lower 
potential HAP emissions rate than owners and operators of heat exchange 
systems with larger recirculation rate systems.
3. Process Vents
    A process vent is a gas stream that is discharged during the 
operation of a particular unit operation (e.g., separation processes, 
purification processes, mixing processes, reaction processes). The gas 
stream(s) may be routed to other unit operations for additional 
processing (e.g., a gas stream from a reactor that is routed to a 
distillation column for separation of products), sent to one or more 
recovery devices, sent to a process vent header collection system 
(e.g., blowdown system) and APCD (e.g., flare, thermal oxidizer, carbon 
adsorber), and/or vented to the atmosphere. Process vents may be 
generated from continuous and/or batch operations, as well as from 
other intermittent types of operations (e.g., maintenance operations). 
If process vents are required to be controlled prior to discharge to 
the atmosphere to meet an applicable emissions standard, then they are 
typically collected and routed to an APCD through a closed vent system.
    The CMAS NESHAP defines batch process vents as a vent from a CMPU 
or vents from multiple CMPUs within a process that are manifolded 
together into a common header, through which a HAP-containing gas 
stream is, or has the potential to be, released to the atmosphere. 
Batch process vents include vents from batch operations and vents with 
intermittent flow from continuous operations that are not combined with 
any stream that originated as a continuous gas stream from the same 
continuous process. Batch process vents at existing affected sources 
are subject to controls if the total organic HAP emissions from all 
batch process vents combined are greater than or equal to 10,000 lb/yr. 
Owners and operators have three options for controlling batch process 
vents meeting the criteria: (1) reduce collective uncontrolled total 
organic HAP emissions from the sum of all batch process vents by 
greater than or equal to 85 percent by weight or to less than or equal 
to 20 ppmv by routing emissions through a closed vent system to any 
combination of control devices (except a flare); (2) route emissions 
from batch process vents containing greater than or equal to 85 percent 
of the uncontrolled total organic HAP through a closed vent system to a 
flare; or (3) comply with the alternative standard specified in 40 CFR 
63.2505, which requires owners and operators to achieve specified 
outlet concentrations for TOC and total hydrogen halides and halogens 
on a continuous basis (both emission limits are 20 ppmv for combustion 
devices, and 50 ppmv for non-combustion devices). The requirements for 
batch process vents at new affected sources are the same, except 
instead of 85 percent control, the CMAS NESHAP requires 90 percent 
control.
    The CMAS NESHAP currently defines ``continuous process vents'' 
using the definition of ``process vent'' in the HON (40 CFR part 63, 
subpart F), but includes a few caveats that address any references to 
the HON. In other words, a ``continuous process vent'' is the point of 
discharge to the atmosphere (or the point of entry into a control 
device, if any) of a gas stream if the gas stream has the 
characteristics specified in 40 CFR 63.107(b) through (h), or meets the 
criteria specified in 40 CFR 63.107(i). Additionally, any references to 
``air oxidation reactors, distillation units, or reactors'' in the HON 
process vent definition, instead mean ``any continuous operation'' 
within the context of the ``continuous process vent'' definition in the 
CMAS NESHAP. The definition of ``continuous process vent'' in the CMAS 
NESHAP also requires a separate determination for the emissions from 
each CMPU, even if emission streams from two or more CMPUs are combined 
prior to discharge to the atmosphere or to a control device. Continuous 
process vents at both existing and new affected sources with a total 
resource effectiveness (TRE) index value \39\ less than or equal to 1.0 
are subject to controls and have three options to meet this 
requirement. Owners and operators can either: (1) reduce emissions of 
total organic HAP by greater than or equal to 95 percent by weight (85 
percent by weight for periods of startup or shutdown) or to less than 
or equal to 20 ppmv by routing emissions through a closed vent system 
to any combination of control devices (except a flare); (2) reduce 
emissions of total organic HAP by routing all emissions through a 
closed vent system to a flare; or (3) comply with the alternative 
standard specified in 40 CFR 63.2505. Continuous process vents at both 
existing and new affected sources with a TRE index value greater than 
1.0 but less than or equal to 4.0 may comply with the operating, 
monitoring, recordkeeping, and reporting requirements of 40 CFR 
63.982(e) if a recovery device is used to maintain a

[[Page 7970]]

TRE greater than 1.0 but less than or equal to 4.0.
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    \39\ The TRE index value is a measure of the supplemental total 
resource requirement per unit VOC (or HAP) reduction. It takes into 
account all the resources which are expected to be used in VOC (or 
HAP) control by thermal oxidation and provides a dimensionless 
measure of resource burden based on cost effectiveness. Resources 
include supplemental natural gas, labor, and electricity. 
Additionally, if the off-gas contains halogenated compounds, 
resources will also include caustic and scrubbing and quench makeup 
water. For the CMAS NESHAP, 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), which is available in the docket for 
this action (Docket ID No. EPA-HQ-OAR-2024-0303).
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    Additionally, both batch and continuous process vents have 
different requirements under the CMAS NESHAP if the process vent stream 
is halogenated. Halogenated batch and continuous process vent streams 
at new or existing sources that are controlled through combustion must 
also use halogen scrubbers to: (1) reduce overall emissions of hydrogen 
halide and halogen HAP after the combustion device by greater than or 
equal to 95-percent, to less than or equal to 0.45 kilogram per hour 
(kg/hr), or to a concentration less than or equal to 20 ppmv; or (2) 
reduce the halogen atom mass emission rate before the combustion device 
to less than or equal to 0.45 kg/hr or to a concentration less than or 
equal to 20 ppmv.
    The CMAS NESHAP also defines metal HAP process vents as the point 
of discharge to the atmosphere (or inlet to a control device, if any) 
of a metal HAP-containing gas stream from any CMPU at an affected 
source containing at least 50 ppmv metal HAP (see 40 CFR 63.11502(b)). 
The metal HAP concentration may be determined using any of the 
following: process knowledge, an engineering assessment, or test data. 
For purposes of the CMAS NESHAP, metal HAP are the compounds containing 
metals listed as HAP in section 112(b) of the CAA. Metal HAP process 
vents at both existing and new affected sources with total metal HAP 
emissions greater than or equal to 400 lb/yr are subject to controls. 
Owners and operators must reduce collective uncontrolled emissions of 
total metal HAP emissions by greater than or equal to 95 percent by 
weight by routing emissions from a sufficient number of the metal 
process vents through a closed vent system to any combination of 
control devices.
    We are proposing to make a change to the definition of ``metal HAP 
process vent'' at 40 CFR 63.11502(b). In 2012, as part of a response to 
a petition for reconsideration, the EPA added the 50 ppmv threshold to 
the definition of ``metal HAP process vent'' at 40 CFR 63.11502(b).\40\ 
This threshold was included because two commenters argued it was 
necessary to better represent GACT, based on their sulfuric acid 
regeneration units already achieving over 95 percent reduction in metal 
HAP. However, the EPA did not conduct any analysis to justify this 
addition. We believe the threshold is inappropriate and has allowed 
process vents previously subject to control to freely emit metal HAP. 
We identified a facility through the emissions inventory (see section 
II.C of this preamble) that is currently subject to the CMAS NESHAP. 
This facility reported emitting 1.99 tpy of nickel compounds from 
process vents. Since the facility emits more than 400 lb/year of metal 
HAP, the provisions in table 4 of 40 CFR part 63, subpart VVVVVV should 
apply. However, if these standards were applied, it would suggest that 
the facility was emitting nearly 40 tpy of nickel compounds 
uncontrolled. This amount of nickel seems unrepresentative of the 
source. It is more likely that, due to the 50 ppmv threshold, the 
facility determined it was not required to control the metal HAP 
process vents. Additionally, we note that this facility was included in 
the original rulemaking's facility list, so the impacts of installing 
controls have already been considered.
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    \40\ On January 30, 2012, the EPA proposed revisions to several 
provisions of the CMAS NESHAP (see 77 FR 4522). The proposed 
revisions were made, in part, in response to a petition for 
reconsideration received by the Administrator following the original 
promulgation of the October 29, 2009, final rule. In the proposed 
rule revisions, the EPA solicited comment on whether the definition 
of ``metal HAP process vent'' was applicable to all types of 
equipment from which metal HAP are emitted. The original rule 
defined a metal HAP process vent as ``the point of discharge to the 
atmosphere (or inlet to a control device, if any) of a metal HAP 
containing gas stream from any CMPU at an affected source,'' 
regardless of the concentration of metal HAP in the stream. Based on 
two commenters' requests, the EPA revised the definition of ``metal 
HAP process vent'' in the final rule revisions (77 FR 75740, 
December 21, 2012), to include only those streams which contain at 
least 50 ppmv metal HAP. The EPA also revised the final rule to 
state that process vents from CMPUs that only contain metal HAP in a 
liquid solution or other form that will not result in particulate 
emissions of metal HAP (e.g., metal HAP that is in ingot, paste, 
slurry or moist pellet form or other form) are not required to 
comply with the metal HAP process vent requirements.
---------------------------------------------------------------------------

    We are now proposing to remove the 50 ppmv threshold from the 
definition of ``metal HAP process vent'' at 40 CFR 63.11502(b). We 
believe this concentration-based threshold is unnecessary because the 
CMAS NESHAP already has a mass-based metal HAP threshold. Specifically, 
if the total uncontrolled metal HAP emissions from all metal HAP 
process vents from a CMPU are less than 400 lb/yr, then owners and 
operators are only subject to recordkeeping requirements, not the metal 
HAP process vent standards in table 4 of the CMAS NESHAP.
    In addition to being a necessary revision made as part of CAA 
section 112(d)(6), the standards were originally promulgated as part of 
the Area Source Program under the Urban Air Toxics Strategy to ensure 
greater than 90 percent of emissions of the 30 urban HAP were subject 
to regulation. In setting the 50 ppmv threshold, vents that were 
previously subject to regulation may have been improperly exempted from 
the standards that were established to address those emissions. By 
proposing to remove the 50 ppmv threshold and returning the definition 
to its originally promulgated state, the standards will once again 
apply to those metal HAP vents previously subject as part of the 
original rulemaking.
    As part of our technology review, we also examined subsequent 
regulatory development efforts and found that the EPA recently 
evaluated emission reduction options for continuous process vents 
subject to the HON, including the removal of the TRE concept in its 
entirety from the NESHAP or revising the TRE index value threshold from 
1.0 to 5.0. The EPA determined that removing the TRE concept in its 
entirety from the HON was cost effective and finalized this in that 
rule (see 89 FR 42932, May 16, 2024). It is reasonable to consider 
removing the TRE concept in its entirety from the CMAS NESHAP given 
that CMPU sources subject to the CMAS NESHAP are similar to CMPU 
sources that are subject to the HON; however, we do not have data 
representative of CMAS continuous process vents to evaluate this 
option. In other words, none of the continuous process vent data that 
the EPA used in the HON rulemaking are representative of an area 
source; and therefore, not representative of a CMAS facility. For 
further information, see the document titled Clean Air Act Section 
112(d)(5) GACT Standard Analysis for Process Vents and Storage Tanks 
that Emit Ethylene Oxide and Section 112(d)(6) Technology Review for 
Process Vents and Storage Tanks Associated with Chemical Manufacturing 
Process Units at Area Sources Subject to the CMAS NESHAP, which is 
available in the docket for this rulemaking. We solicit comment and 
data on whether removing the TRE concept in its entirety is feasible 
for continuous process vents from CMAS CMPUs.
    Except for the proposed change to the definition of `metal HAP 
process vent' and the TRE options we could not evaluate due to 
insufficient data on CMAS continuous process vents, we found no 
additional practices, processes, or control technologies beyond those 
already required by the CMAS NESHAP for process vents. Our review did 
not reveal any other developments in emissions reduction practices for 
CMAS process vents that are any more stringent than the GACT standards 
in the CMAS NESHAP.

[[Page 7971]]

Therefore, we are not proposing any other changes to the CMAS NESHAP 
for process vents pursuant to CAA section 112(d)(6).
4. Storage Tanks
    Storage tanks are used to store liquid and gaseous feedstocks for 
use in a process, as well as to store liquid and gaseous products from 
a process. Most CMAS storage tanks are designed for operation at 
atmospheric or near atmospheric pressures; pressure vessels are used to 
store compressed gases and liquefied gases. Atmospheric storage tanks 
are typically cylindrical with a vertical orientation, and they are 
constructed with either a fixed roof or a floating roof. Some, 
generally small, atmospheric storage tanks are oriented horizontally. 
Pressure vessels are either spherical or horizontal cylinders. As 
discussed in section IV.B.1 of this preamble, we are proposing new GACT 
standards for pressure vessels.
    The CMAS NESHAP requires owners and operators to control emissions 
from storage tanks with: (1) capacities greater than or equal to 40,000 
gallons storing a liquid with a maximum true vapor pressure (MTVP) 
greater than or equal to 5.2 kPa but less than 76.6 kPa; (2) capacities 
greater than or equal to 20,000 gallons and less than 40,000 gallons 
storing a liquid with a MTVP greater than or equal to 27.6 kPa and less 
than 76.6 kPa; and (3) capacities greater than or equal to 20,000 
gallons storing a liquid with a MTVP greater than or equal to 76.6 kPa. 
Owners and operators of storage tanks meeting any of these criteria are 
required to reduce total organic HAP emissions by greater than or equal 
to 95 percent by weight by operating and maintaining a closed vent 
system and control device (other than a flare), reduce total HAP 
emissions by operating and maintaining a closed vent system and a 
flare, vapor balance, or route emissions to a fuel gas system or 
process. Owners and operators of storage tanks meeting the first two 
sets of capacity and MTVP criterion can also comply with the 
requirements of 40 CFR part 63, subpart WW which requires owners and 
operators to operate and maintain an external floating roof (EFR) or 
internal floating roof (IFR) according to specific monitoring, 
recordkeeping, and reporting standards.
    Additionally, storage tanks within the capacity and MTVP thresholds 
listed in the preceding paragraph have different requirements under the 
CMAS NESHAP if the storage tank emits a halogenated vent stream. 
Halogenated storage tank vent streams at new or existing sources that 
are controlled through a combustion device must also use a halogen 
reduction device to: (1) reduce emissions of hydrogen halide and 
halogen HAP after the combustion device by greater than or equal to 95-
percent, to less than or equal to 0.45 kg/hr, or to a concentration 
less than or equal to 20 ppmv; or (2) reduce the halogen atom mass 
emission rate before the combustion device to less than or equal to 
0.45 kg/hr or to a concentration less than or equal to 20 ppmv.
    We did not identify any practices, processes, or control 
technologies beyond those already required by the CMAS NESHAP for 
storage tanks. Our review did not reveal any developments in emissions 
reduction practices for CMAS storage tanks that are any more stringent 
than the GACT standards in the CMAS NESHAP. Therefore, we are not 
proposing any changes to the CMAS NESHAP for storage tanks pursuant to 
CAA section 112(d)(6). As part of our technology review, we examined 
subsequent regulatory development efforts and found that the EPA 
recently evaluated emission reduction options for storage vessels \41\ 
subject to the HON, including revising capacity and MTVP thresholds, 
requiring certain IFR controls pursuant to 40 CFR part 63, subpart WW, 
and requiring the conversion of EFRs to IFRs through use of geodesic 
domes. The EPA determined that revising capacity and MTVP thresholds 
and requiring certain IFR controls pursuant to 40 CFR part 63, subpart 
WW was cost effective for HON storage vessels and finalized this in the 
rule (see 89 FR 42932, May 16, 2024). It is reasonable to consider 
these Control Options for the CMAS NESHAP given that CMPU sources 
subject to the CMAS NESHAP are similar to CMPU sources that are subject 
to the HON; however, we do not have data representative of CMAS storage 
tanks to evaluate these options. In other words, none of the storage 
vessel data that the EPA used in the recent HON rulemaking are 
representative of an area source; and therefore, not representative of 
a CMAS facility. Even still, we note that the CMAS NESHAP already 
includes complying with 40 CFR part 63, subpart WW as an option. 
Additionally, the EPA found the option of converting EFRs to IFRs 
through the use of geodesic domes to not be cost effective for HON 
storage vessels; therefore, we anticipate this option would likewise 
not be cost effective for CMAS storage tanks. For further information, 
see the document titled Clean Air Act Section 112(d)(5) GACT Standard 
Analysis for Process Vents and Storage Tanks that Emit Ethylene Oxide 
and Section 112(d)(6) Technology Review for Process Vents and Storage 
Tanks Associated with Chemical Manufacturing Process Units at Area 
Sources Subject to the CMAS NESHAP, which is available in the docket 
for this rulemaking.
---------------------------------------------------------------------------

    \41\ The HON uses the term ``storage vessel'' in lieu of 
``storage tank'' like the CMAS NESHAP.
---------------------------------------------------------------------------

5. Wastewater
    HAP are emitted into the air from wastewater collection, storage, 
and treatment systems that are uncovered or open to the atmosphere 
through volatilization of the compound at the liquid surface. Emissions 
occur by diffusive or convective means, or both. Diffusion occurs when 
organic pollutant concentrations at the water surface are much higher 
than ambient concentrations. The organic pollutants volatilize, or 
diffuse into the air, to reach equilibrium between the aqueous and 
vapor phases. Convection occurs when air flows over the water surface, 
sweeping organic vapors from the water surface into the air. The rate 
of volatilization is related directly to the speed of the air flow over 
the water surface.
    The CMAS NESHAP defines wastewater to mean water that is discarded 
from a CMPU or control device and that contains at least 5 ppmw of any 
HAP listed in table 9 to 40 CFR part 63, subpart G and has an annual 
average flow rate of 0.02 liters per minute (lpm). Wastewater means 
both process wastewater \42\ and maintenance wastewater \43\ that is 
discarded from a CMPU or control device.
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    \42\ Process wastewater means wastewater which, during 
manufacturing or processing, comes into direct contact with or 
results from the production or use of any raw material, intermediate 
product, finished product, by-product, or waste product. Examples 
are product tank drawdown or feed tank drawdown; water formed during 
a chemical reaction or used as a reactant; water used to wash 
impurities from organic products or reactants; water used to cool or 
quench organic vapor streams through direct contact; and condensed 
steam from jet ejector systems pulling vacuum on vessels containing 
organics.
    \43\ Maintenance wastewater means wastewater generated by the 
draining of process fluid from components in the CMPU into an 
individual drain system in preparation for or during maintenance 
activities. Maintenance wastewater can be generated during planned 
and unplanned shutdowns and during periods not associated with a 
shutdown. Examples of activities that can generate maintenance 
wastewater include descaling of heat exchanger tubing bundles, 
cleaning of distillation column traps, draining of pumps into an 
individual drain system, and draining of portions of the CMPU for 
repair. Wastewater from routine cleaning operations occurring as 
part of batch operations is not considered maintenance wastewater.
---------------------------------------------------------------------------

    For each wastewater stream containing partially soluble HAP at a 
concentration greater than or equal to

[[Page 7972]]

10,000 ppmw that also has separate organic and water phases, the CMAS 
NESHAP requires owners and operators to use a decanter, steam stripper, 
thin film evaporator, or distillation unit to separate the water phase 
from the organic phase(s); and the organic layer must be recycled to a 
process, used as a fuel, or disposed of as hazardous waste either 
onsite or offsite. The CMAS NESHAP also provides an alternative 
compliance option that allows owners and operators to hard-pipe the 
entire stream to onsite treatment as a hazardous waste or to a point of 
transfer to onsite or offsite hazardous waste treatment. For single 
phase wastewater streams and the aqueous phase for two phase streams, 
the CMAS NESHAP requires the wastewater streams be sent to a wastewater 
treatment process.
    As part of our technology review, we found that many of the NESHAP 
for different chemical manufacturing source categories (e.g., the HON, 
MON, and PEPO NESHAP) require treatment of wastewater streams that meet 
certain flow and HAP concentration levels. These standards require 
either the use of a treatment unit that meets specified design criteria 
or that achieves specified destruction efficiencies for the HAP in the 
wastewater. They also typically require the use of covers and other 
techniques to suppress emissions from the wastewater conveyance system 
and treatment units. During the original CMAS rulemaking (74 FR 56008, 
October 29, 2009), the EPA evaluated treating CMAS wastewater streams 
using controls that meet the HON requirements; however, the EPA found 
the option to not be cost effective.\44\ We find no reason for the HON 
requirements to be any more cost effective today compared to the cost 
effectiveness that was determined in 2008. Therefore, we are not 
proposing any changes to the CMAS NESHAP for wastewater pursuant to CAA 
section 112(d)(6).
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    \44\ See 73 FR 58352, October 6, 2008. ``We are proposing that 
[wastewater] controls needed to meet more stringent emission limits 
like those required by the HON do not represent GACT for either 
subcategory because the costs are unreasonable.''
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6. Flares
    The CMAS NESHAP allows for the use of a flare to control emissions 
(except halogenated emissions) from batch process vents, continuous 
process vents, and/or storage tanks. The CMAS NESHAP points to the 
flare requirements specified in 40 CFR part 63, subpart SS which 
requires owners and operators to conduct a flare compliance assessment 
to demonstrate initial compliance, and continuously monitor applicable 
operating parameters in accordance with 40 CFR 63.11 to demonstrate 
continuous compliance. Although GACT for batch process vents is 
emission reductions of 85 percent by weight (for existing) and 90 
percent by weight (for new); for continuous process vents is 95 percent 
by weight (except 85 percent by weight for startup and shutdown); and 
for storage tanks is 95 percent by weight, the available data at the 
time the CMAS NESHAP was promulgated suggested that flares meeting 
these design and operating requirements of 40 CFR 63.11 would achieve a 
minimum destruction efficiency of no less than 98 percent by weight 
emissions control. However, more recent studies on flare performance 
\45\ indicate that the requirements in 40 CFR 63.11 are inadequate to 
ensure 98 percent by weight control. These studies compelled the EPA to 
finalize a suite of operational and monitoring requirements for 
refinery flares on December 1, 2015 (80 FR 75178-75354; see 40 CFR 
63.670 and 40 CFR 63.671) including requirements addressing: (1) the 
presence of a pilot flame; (2) visible emissions; (3) flare tip 
velocity; (4) net heating value of flare combustion zone gas; and (5) 
net heating value dilution parameter (if the flare actively receives 
perimeter assist air). The EPA determined that this suite of 
operational and monitoring requirements for flares is necessary to 
ensure the level of destruction efficiency needed to conform with the 
petroleum refineries NESHAP. Importantly, given that the flare dataset 
that formed the underlying basis of the new standards for refinery 
flares also included flares at olefin and other petrochemical plants, 
the EPA also revised the suite of operational and monitoring 
requirements for flares in other chemical manufacturing source 
categories, including the EMACT standards (85 FR 40386, July 6, 2020; 
see 40 CFR 63.1103(e)(4)), the Organic Liquids Distribution (OLD) 
NESHAP (85 FR 40740, July 7, 2020; see 40 CFR 63.2380(a)), the MON (85 
FR 49084, August 20, 2020; see 40 CFR 63.2450(e)(5)), and the HON and 
P&R I NESHAP (89 FR 42932, May 16, 2024; see 40 CFR 63.108 and 63.508, 
respectively). The EPA did this for the same reason as was done for the 
petroleum refineries NESHAP, to ensure the level of destruction 
efficiency needed to conform with each NESHAP.
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    \45\ For a list of studies, refer to the technical report titled 
Parameters for Properly Designed and Operated Flares, in Docket ID 
Item No. EPA-HQ-OAR-2010-0682-0191. This document can also be found 
at https://www.epa.gov/stationary-sources-air-pollution/review-peer-review-parameters-properly-designed-and-operated-flares.
---------------------------------------------------------------------------

    We acknowledge that none of the performance standards in the CMAS 
NESHAP are as stringent as 98 percent by weight emissions control; 
however, under CAA section 112(d)(6), we still evaluated the option 
(i.e., Control Option 1) to require all flares at CMAS facilities to 
comply with the same suite of flare operational and monitoring 
requirements included in the petroleum refineries NESHAP, EMACT 
standards, OLD NESHAP, MON, HON, and P&R I and Group II Polymers and 
Resins NESHAP. The monitoring equipment needed to comply with the suite 
of flare operational and monitoring requirements (i.e., hydrogen 
analyzers, calorimeters, and flow monitors) were not identified or 
considered during development of the original GACT standards; 
therefore, we consider this a development under this technology review. 
Additionally, we believe the suite of flare operational and monitoring 
requirements could be relevant to the CMAS NESHAP due to the 
similarities between processes at chemical manufacturing plants, 
regardless of size.
    Using information from the CMAS emissions inventory data (see 
section II.C.2 of this preamble), we estimated there are 22 flares at 
20 CMAS facilities that would be affected by Control Option 1 (we did 
not identify any other flares in the CMAS emissions inventory). To 
avoid double counting, we excluded two of the 22 flares from our 
analysis that emit EtO; and instead, we included them in our GACT 
analysis discussed in section IV.A.6 of this preamble. We estimated 
costs for each flare for a given facility, considering current 
monitoring systems already installed on each individual flare. Given 
that the same type of equipment is used for flares in the CMAS 
categories and for the petroleum refinery sector, we estimated costs 
for any additional monitoring systems needed based on installed costs 
received from petroleum refineries and, if installed costs were 
unavailable, we estimated costs based on vendor-purchased equipment. 
The baseline emission estimate and the emission reductions achieved by 
Control Option 1 were estimated based on the CMAS emissions inventory 
data (see section II.C.2 of this preamble) and current vent gas and 
steam flow data submitted by industry representatives.\46\

[[Page 7973]]

The results of the impact estimates for Control Options 1 are 
summarized in table 10 of this preamble. See the document titled Clean 
Air Act Section 112(d)(5) GACT Standard Analysis for Flares that Emit 
Ethylene Oxide and Section 112(d)(6) Technology Review for Flares 
Associated with Chemical Manufacturing Process Units at Area Sources 
Subject to the CMAS NESHAP, which is available in the docket for this 
rulemaking, for details on the assumptions and methodologies used in 
this analysis. We determined that Control Option 1 is not cost 
effective and are not proposing to revise the CMAS NESHAP to reflect 
the requirements of this option pursuant to CAA section 112(d)(6).
---------------------------------------------------------------------------

    \46\ To estimate the baseline control efficiency of VOC and HAP 
anticipated by applying Control Option 1, we reviewed data submitted 
to the EPA in 2011 by the API, the ACC, and the NPRA, now known as 
the AFPM. This dataset includes detailed hourly operational 
information for 38 steam-assisted flares, characterizing different 
operating conditions by waste gas flow rate, steam flow rate, waste 
gas composition, and duration of that operating condition.

  Table 10--Nationwide Emissions Reductions and Cost Impacts of Control Option 1 for Requiring the Suite of Operational and Monitoring Requirements for
                                                                Flares at CMAS Facilities
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                         Total
                                                                        capital        Total        VOC emission       HAP emission         HAP cost
                           Control option                             investment    annualized    reductions (tpy)   reductions (tpy)  effectiveness ($/
                                                                          ($)      costs ($/yr)                                               ton)
--------------------------------------------------------------------------------------------------------------------------------------------------------
1..................................................................   26,000,000     6,160,000              1,114               89.4             68,200
--------------------------------------------------------------------------------------------------------------------------------------------------------

7. Fenceline Monitoring
    Fenceline monitoring refers to the placement of monitors along the 
perimeter of a facility to measure pollutant concentrations. Coupled 
with requirements for root cause analysis and corrective action upon 
triggering an actionable level, this management practice is a 
development in practices considered under CAA section 112(d)(6) for the 
purposes of managing fugitive emissions. The measurement of pollutant 
concentrations and comparison to concentrations estimated from mass 
emissions via dispersion modeling is used to verify emission estimates 
from a facility's emissions inventory. If concentrations at the 
fenceline are greater than expected, potential causes may include 
underreported or unknown emissions, leaking equipment, or other issues, 
usually related to ground-level fugitive emissions. Fenceline 
monitoring also provides information on the location of potential 
emissions sources because it provides complete spatial coverage of a 
facility. Further, when used with a mitigation strategy, such as root 
cause analysis and corrective action upon exceedance of an action 
level, fenceline monitoring can be effective in reducing emissions and 
reducing the uncertainty associated with emissions estimation and 
characterization. Finally, public reporting of fenceline monitoring 
data provides public transparency and greater visibility, leading to 
more focus and effort in reducing emissions.
    The EPA has successfully applied fenceline monitoring to the 
petroleum refineries source category as a technique to manage and 
reduce benzene emissions from fugitive emissions sources such as 
storage vessels, wastewater treatment systems, and leaking equipment. 
In 2015, the EPA promulgated the RTR for the petroleum refineries 
source category and required that refineries install and operate 
fenceline monitors following EPA Method 325 A/B to monitor benzene 
emissions. Additionally, the 2015 rule required that refineries conduct 
a root cause analysis to identify sources of high fenceline monitoring 
readings (i.e., above an annual action level) and then develop a 
corrective action plan to address the sources and reduce emissions to a 
level that will bring fenceline monitoring concentrations below the 
action level.\47\ To date, the EPA has received fenceline monitoring 
data from petroleum refineries for more than 5 years.\48\ These data 
show that petroleum refinery fenceline concentrations have dropped by 
an average of 30 percent since the inception of the monitoring program 
requirements and illustrate that fenceline monitoring is an effective 
tool in reducing emissions and preserving emission reductions on an 
ongoing basis for these sources.
---------------------------------------------------------------------------

    \47\ 40 CFR 63.658(f)-(h).
    \48\ Quarterly fenceline monitoring reports are available 
through the EPA's WebFIRE database at https://cfpub.epa.gov/webfire/. The EPA has also developed a dashboard to improve public 
access to this data. The dashboard is available at https://awsedap.epa.gov/public/extensions/Fenceline_Monitoring/Fenceline_Monitoring.html?sheet=MonitoringDashboard.
---------------------------------------------------------------------------

    Additionally, in 2024, the EPA promulgated amendments to the HON 
(40 CFR part 63, subpart H) and the P&R I NESHAP (40 CFR part 63, 
subpart U) that included work practice standards requiring owners and 
operators to conduct fenceline monitoring for any of six specific HAP 
(i.e., benzene; 1,3-butadiene; ethylene dichloride; vinyl chloride; 
EtO; and chloroprene) if their affected source uses, produces, stores, 
or emits any of them, and conduct root cause analysis and corrective 
action upon exceeding the annual average concentration action level 
established for each HAP. The final HON and P&R I NESHAP amendments 
require owners and operators to conduct passive diffusive tube 
fenceline monitoring for benzene, 1,3-butadiene, chloroprene, and 
ethylene dichloride in accordance with EPA Methods 325A/B of 40 CFR 
part 63, appendix A, and to use canister sampling in accordance with 
EPA Method 327 of 40 CFR part 63, appendix A, for EtO and vinyl 
chloride.\49\
---------------------------------------------------------------------------

    \49\ In the same action (see 89 FR 42932, May 16, 2024), the EPA 
also finalized EPA Method 327 of 40 CFR part 63, appendix A, as a 
canister sampling and analysis method that provides procedures for 
measuring trace levels of targeted VOC (including organic HAP) in 
ambient air.
---------------------------------------------------------------------------

    Given the similarities between CMAS CMPUs and sources subject to 
the HON or P&R I NESHAP, we evaluated the application of fenceline 
monitoring as a development in practices, processes, and control 
technologies pursuant to CAA section 112(d)(6). Non-EtO pollutants for 
which there are established EPA Methods to measure fenceline 
concentrations and which are one of the fifteen urban HAP regulated as 
part of the CMAS NESHAP include 1,3-butadiene, 1,3-dichloropropene, 
ethylene dichloride, and chloroform. We reviewed the 2017 NEI to 
determine whether CMAS facilities reported emissions of 1,3-butadiene, 
chloroform 1,3-dichloropropene, and ethylene dichloride. Based on this 
review, we determined that at most CMAS facilities that emit 1,3-
butadiene, chloroform, 1,3-dichloropropene, and ethylene dichloride, 
small amounts of these HAP are emitted from fugitive sources. Most of 
the reported emissions are attributed to non-source category emission 
sources. Based on this information, the EPA is not proposing to 
implement a fenceline monitoring program for non-EtO pollutants under 
CAA section 112(d)(6). However, we are proposing a

[[Page 7974]]

fenceline monitoring program to limit fugitive EtO emissions under CAA 
section 112(d)(5), as discussed in section IV.A.7 of this preamble and 
in further detail in the document titled Clean Air Act Section 
112(d)(5) GACT Standard Analysis and CAA Section 112(d)(6) Technology 
Review for Fenceline Monitoring for Chemical Manufacturing Process 
Units Associated with the Chemical Manufacturing Area Sources NESHAP 
available in the docket for this action.

D. What other actions are we proposing, and what is the rationale for 
those actions?

    In addition to the proposed GACT standards pursuant to CAA 
112(d)(5) (see sections IV.A and IV.B of this preamble) and our 
proposed actions on the CAA 112(d)(6) review (see section IV.C of this 
preamble), we are also proposing other changes to the CMAS NESHAP, 
including: revisions to the recordkeeping and reporting requirements to 
require the use of electronic reporting of certain reports; performance 
testing once every 5 years for batch and continuous process vents to 
demonstrate compliance with emission limits; and corrections to section 
reference errors and other minor editorial revisions. Our rationale and 
proposed changes related to these issues are discussed below.
1. Electronic Reporting
    The EPA is proposing that owners and operators subject to the CMAS 
NESHAP submit electronic copies of required notification of compliance 
status reports, performance test reports, flare management plans, and 
periodic reports (including fenceline monitoring reports) through the 
EPA's Central Data Exchange using the Compliance and Emissions Data 
Reporting Interface (CEDRI) (see proposed edits to 40 CFR 
63.11496(f)(3)(ii) for notification of compliance status reports 
associated with the HAP metals emissions limit, proposed 40 CFR 
63.11501(b) for notification of compliance status reports, 40 CFR 
63.11496(g)(1)(iv) for performance test reports, 40 CFR 63.11501(d) for 
semiannual compliance reports, and references to flare requirements 
which include flare management plans in proposed entries 4.a to tables 
2 and 3 to subpart VVVVVV of part 63 and proposed entry 5.a to table 5 
to subpart VVVVVV of part 63). A description of the electronic data 
submission process is provided in the document titled Electronic 
Reporting Requirements for New Source Performance Standards (NSPS) and 
National Emission Standards for Hazardous Air Pollutants (NESHAP) 
Rules, available in the docket for this action.
    The proposed rule requires that performance test results collected 
using test methods that are supported by the EPA's Electronic Reporting 
Tool (ERT) as listed on the ERT website \50\ at the time of the test be 
submitted in the format generated through the use of the ERT or an 
electronic file consistent with the xml schema on the ERT website, and 
other performance test results be submitted in portable document format 
(PDF) using the attachment module of the ERT. Flare management plans 
would be uploaded as a PDF file.
---------------------------------------------------------------------------

    \50\ https://www.epa.gov/electronic-reporting-air-emissions/electronic-reporting-tool-ert.
---------------------------------------------------------------------------

    For semiannual compliance reports (including fenceline monitoring 
reports), the proposed rules require that owners and operators use an 
appropriate spreadsheet template to submit information to CEDRI. A 
draft version of the proposed templates for these reports is included 
in the docket for this action.\51\ The EPA specifically requests 
comment on the content, layout, and overall design of the templates. We 
are proposing owners and operators begin using the templates for 
semiannual compliance reports other than fenceline reports within 3 
years of the publication date of the final rule in the Federal 
Register, or after the reporting template for the subpart has been 
available on the CEDRI website for 1 year, whichever date is later. 
Owners and operators would begin using the templates for fenceline 
monitoring reports starting when the first fenceline monitoring report 
is due.
---------------------------------------------------------------------------

    \51\ See 
part_63_subpart_VVVVVV_63.11501(d)_semiannual_compliance.xlsx 
available in the docket for this action.
---------------------------------------------------------------------------

    The electronic submittal of the reports addressed in these proposed 
rulemakings will increase the usefulness of the data contained in those 
reports, is in keeping with current trends in data availability and 
transparency, will further assist in the protection of public health 
and the environment, will improve compliance by facilitating the 
ability of regulated facilities to demonstrate compliance with 
requirements and by facilitating the ability of delegated state, local, 
Tribal, and territorial air agencies and the EPA to assess and 
determine compliance, and will ultimately reduce burden on regulated 
facilities, delegated air agencies, and the EPA.\52\ Electronic 
reporting also eliminates paper-based, manual processes, thereby saving 
time and resources, simplifying data entry, eliminating redundancies, 
minimizing data reporting errors, and providing data quickly and 
accurately to the affected facilities, air agencies, the EPA, and the 
public. Moreover, electronic reporting is consistent with the EPA's 
plan \53\ to implement Executive Order 13563 and is in keeping with the 
EPA's Agency-wide policy \54\ developed in response to the White 
House's Digital Government Strategy.\55\ For more information on the 
benefits of electronic reporting, see the document titled Electronic 
Reporting Requirements for New Source Performance Standards (NSPS) and 
National Emission Standards for Hazardous Air Pollutants (NESHAP) 
Rules, referenced earlier in this section.
---------------------------------------------------------------------------

    \52\ We are proposing at 40 CFR 63.11503(b)(5) that the approval 
to an alternative to any electronic reporting to the EPA proposed 
for the CMAS NESHAP cannot be delegated to state, local, or Tribal 
agencies.
    \53\ EPA's Final Plan for Periodic Retrospective Reviews, August 
2011. Available at: https://www.regulations.gov/document?D=EPA-HQ-OA-2011-0156-0154.
    \54\ E-Reporting Policy Statement for EPA Regulations, September 
2013. Available at: https://www.epa.gov/sites/production/files/2016-03/documents/epa-ereporting-policy-statement-2013-09-30.pdf.
    \55\ Digital Government: Building a 21st Century Platform to 
Better Serve the American People, May 2012. Available at: https://obamawhitehouse.archives.gov/sites/default/files/omb/egov/digital-government/digital-government.html.
---------------------------------------------------------------------------

2. Affirmative Defense
    As part of the December 21, 2012, CMAS NESHAP final rule (see 77 FR 
75740), the EPA included the ability to assert an affirmative defense 
to civil penalties for violations caused by malfunctions (see 40 CFR 
63.11501(e)) in an effort to create a system that incorporated some 
flexibility, recognizing that there is a tension, inherent in many 
types of air regulation, to ensure adequate compliance while 
simultaneously recognizing that despite the most diligent of efforts, 
emission standards may be violated under circumstances entirely beyond 
the control of the source. Although the EPA recognized that its case-
by-case enforcement discretion provides sufficient flexibility in these 
circumstances, it included the affirmative defense provision to provide 
a more formalized approach and more regulatory clarity. See 
Weyerhaeuser Co. v. Costle, 590 F.2d 1011, 1057-58 (D.C. Cir. 1978) 
(holding that an informal case-by-case enforcement discretion approach 
is adequate); but see Marathon Oil Co. v. EPA, 564 F.2d 1253, 1272-73 
(9th Cir. 1977) (requiring a more formalized approach to consideration 
of ``upsets beyond the control of the permit holder.''). Under the 
EPA's regulatory

[[Page 7975]]

affirmative defense provisions, if a source could demonstrate in a 
judicial or administrative proceeding that it had met the requirements 
of the affirmative defense in the regulation, civil penalties would not 
be assessed. However, the court vacated the affirmative defense in one 
of the EPA's CAA section 112 regulations. NRDC v. EPA, 749 F.3d 1055 
(D.C. Cir., 2014) (vacating affirmative defense provisions in the CAA 
section 112 rule establishing emission standards for Portland cement 
kilns). The court found that the EPA lacked authority to establish an 
affirmative defense for private civil suits and held that under the 
CAA, the authority to determine civil penalty amounts in such cases 
lies exclusively with the courts, not the EPA. Specifically, the court 
found: ``As the language of the statute makes clear, the courts 
determine, on a case-by-case basis, whether civil penalties are 
`appropriate.' '' See NRDC, 749 F.3d at 1063 (``[U]nder this statute, 
deciding whether penalties are `appropriate' in a given private civil 
suit is a job for the courts, not EPA.'').\56\ In light of NRDC, the 
EPA is proposing to remove all of the regulatory affirmative defense 
provisions from the CMAS NESHAP at 40 CFR 63.11501(e) in its entirety 
and the definition of ``affirmative defense'' at 40 CFR 63.11502(b). As 
explained above, if a source is unable to comply with emissions 
standards as a result of a malfunction, the EPA may use its case-by-
case enforcement discretion to provide flexibility, as appropriate. 
Further, as the court recognized, in an EPA or citizen enforcement 
action, the court has the discretion to consider any defense raised and 
determine whether penalties are appropriate. Cf. NRDC, 749 F.3d at 1064 
(arguments that violation was caused by unavoidable technology failure 
can be made to the courts in future civil cases when the issue arises). 
The same is true for the presiding officer in EPA administrative 
enforcement actions.\57\
---------------------------------------------------------------------------

    \56\ The court's reasoning in NRDC focuses on civil judicial 
actions. The court noted that ``EPA's ability to determine whether 
penalties should be assessed for CAA violations extends only to 
administrative penalties, not to civil penalties imposed by a 
court.'' Id.
    \57\ Although the NRDC case does not address the EPA's authority 
to establish an affirmative defense to penalties that are available 
in administrative enforcement actions, we are not including such an 
affirmative defense in the proposed rule. As explained above, such 
an affirmative defense is not necessary. Moreover, assessment of 
penalties for violations caused by malfunctions in administrative 
proceedings and judicial proceedings should be consistent. Cf. CAA 
section 113(e) (requiring both the Administrator and the court to 
take specified criteria into account when assessing penalties).
---------------------------------------------------------------------------

    The EPA previously proposed to remove the affirmative defense 
provisions from the CMAS NESHAP as part of the Removal of Affirmative 
Defense Provisions from Specified New Source Performance Standards and 
National Emissions Standards for Hazardous Air Pollutants action (see 
89 FR 52425, June 24, 2024). We now propose the removal of these 
provisions as part of this action. We are soliciting comment on our 
proposal to remove the affirmative defense provisions from the CMAS 
NESHAP as part of this rulemaking. Comments previously submitted on the 
Removal of Affirmative Defense Provisions from Specified New Source 
Performance Standards and National Emissions Standards for Hazardous 
Air Pollutants proposal will not be considered as part of this action 
and must be submitted to the docket for this action (Docket ID No. EPA-
HQ-OAR-2024-0303) in order to be considered.
3. Technical and Editorial Changes
    We are proposing several technical amendments and definition 
revisions to improve the clarity and enforceability of certain 
provisions in the CMAS NESHAP. This section of the preamble described 
these additional proposed revisions and our rationale.
a. Certain Definitions That Refer to the HON
    We note that to remove redundancy and improve consistency, the EPA 
recently finalized moving all of the definitions from NESHAP subpart G 
(i.e., 40 CFR 63.111) into the definition section of NESHAP subpart F 
(i.e., 40 CFR 63.101) (see 89 FR 42932, May 16, 2024). Given that the 
CMAS NESHAP directly references these subparts for certain definitions 
(see 40 CFR 63.11502(a)), we are proposing to revise the phrasing used 
in 40 CFR 63.11502(a) to point to NESHAP subpart F in instances where a 
definition in the CMAS NESHAP points to NESHAP subpart G. We are also 
proposing editorial changes in 40 CFR 63.11502(b) that clarify 
references in the CMAS NESHAP definition of ``point of determination'' 
to properly cite the correct HON subpart.
b. Performance Testing
    The EPA is proposing at 40 CFR 63.11496(g)(1)(iii) and 40 CFR 
63.11497(g)(1)(iii) performance testing once every 5 years to 
demonstrate compliance with organic HAP emission limits for batch and 
continuous process vents and storage tanks (for owners and operators 
that route emissions to a control device other than a flare). 
Similarly, we are also proposing at 40 CFR 63.11496(f)(3)(iv), (4), and 
(5) performance testing once every 5 years to demonstrate compliance 
with the metal HAP emission limit for batch and continuous process 
vents. We determined that periodic emission testing should be required 
to help ensure continuous compliance. Currently, facilities conduct a 
one-time performance test, engineering assessment, or design evaluation 
and then monitor operating parameters. A design evaluation (in lieu of 
performance testing) is currently allowed at 40 CFR 63.11496(g)(2) for 
determining initial compliance with a percent reduction or outlet 
concentration process vent organic HAP emission limit. A design 
evaluation (in lieu of performance testing) is also currently allowed 
at 40 CFR 63.985(b)(1)(i) (via items 1.b, 2.a, and 3.a of table 5 to 
the CMAS NESHAP) for determining initial compliance with a percent 
reduction or outlet concentration storage tank organic HAP emission 
limit. An engineering assessment (in lieu of performance testing) is 
currently allowed at 40 CFR 63.11496(f)(3)(ii) for determining initial 
compliance with the percent reduction process vent metal HAP emission 
limit. However, we are proposing to remove the design evaluation option 
at 40 CFR 63.11496(g)(2) and table 5 to the CMAS NESHAP, and the 
engineering assessment option at 40 CFR 63.11496(f)(3)(ii), and 
instead, require on-going performance tests at proposed 40 CFR 
63.11496(f)(3)(iv), (4), and (5), and 40 CFR 63.11496(g)(1)(iii) (for 
owners and operators using a control device other than a flare to 
comply with the emission limits and other requirements for batch and 
continuous process vents) and 40 CFR 63.11497(g)(1)(iii) (for owners 
and operators using a control device other than a flare to comply with 
the emission limits and other requirements for storage tanks). We are 
proposing that the on-going performance tests be conducted at a minimum 
frequency of once every 5 years to supplement the parameter monitoring 
and to ensure that emission controls continue to operate as 
demonstrated during the initial performance test. We are soliciting 
comment and data on whether design evaluations and engineering 
assessments are appropriate for demonstrating compliance for certain 
APCDs.
    We are also proposing to add a performance testing requirement at 
40 CFR 63.11496(g)(1)(iii) and 40 CFR 63.11497(g)(1)(iii) intended to 
replace a

[[Page 7976]]

portion of the performance testing requirements of 40 CFR 
63.997(e)(1)(i). The proposal does not include the language that 
precludes startup and shutdown periods from being considered 
``representative'' for purposes of performance testing, and instead 
allows performance testing during periods of startup or shutdown if 
specified by the Administrator. In addition, as specified in 40 CFR 
63.997(e)(1)(i), performance tests should not be conducted during 
malfunctions because conditions during malfunctions are often not 
representative of normal operating conditions. The EPA is also 
proposing to add language at 40 CFR 63.11496(g)(1)(iii) and 40 CFR 
63.11497(g)(1)(iii) that requires the owner or operator maintain 
records of process information that is necessary to document operating 
conditions during the test and include in such record an explanation to 
support that such conditions represent the entire range of normal 
operation, including operational conditions for maximum emissions if 
such emissions are not expected during maximum production.
c. Other Editorial and Technical Corrections
    The EPA is proposing additional changes that address technical and 
editorial corrections for the CMAS NESHAP. The most significant of 
these corrections are summarized in table 11 of this preamble. Please 
see the document Proposed Regulation Edits for 40 CFR part 63 Subpart 
VVVVVV: National Emission Standards for Hazardous Air Pollutants for 
Chemical Manufacturing Area Sources, available in the docket for this 
rulemaking, to review all of the proposed technical and editorial 
corrections.

   Table 11--Proposed Technical and Editorial Corrections for the CMAS NESHAP (Not Discussed Elsewhere in This
                                                    Preamble)
----------------------------------------------------------------------------------------------------------------
              Provision                               Issue summary                      Proposed revision
----------------------------------------------------------------------------------------------------------------
40 CFR 63.11494(c)(2)(iv)............  Provision refers to specific NAICS codes    The EPA is proposing to add
                                        but does not specify which version (i.e.,   language to specify the 2007
                                        year) to use.                               version of the NAICS code.
40 CFR 63.11495(d)...................  Provision does not include all language on  The EPA is proposing to add
                                        the general duty to minimize emissions.     the sentence ``The general
                                                                                    duty to minimize emissions
                                                                                    does not require the owner
                                                                                    or operator to make any
                                                                                    further efforts to reduce
                                                                                    emissions if levels required
                                                                                    by the applicable standard
                                                                                    have been achieved.''
40 CFR 63.11496(g)(5)................  Provision is redundant to the language at   The EPA is proposing to
                                        40 CFR 63.11496(i).                         remove the provision to
                                                                                    eliminate redundancy and
                                                                                    reduce confusion with how
                                                                                    the standards are applied.
40 CFR 63.11497(a)...................  Provision does not contain a heading;       The EPA is proposing to add
                                        therefore, is inconsistent with other       the heading: ``Organic HAP
                                        paragraphs within the section.              emissions from storage
                                                                                    tanks'' for consistency with
                                                                                    the rest of the paragraphs
                                                                                    included in the section.
40 CFR 63.11497(c)...................  Provision does not contain a heading;       The EPA is proposing to add
                                        therefore, is inconsistent with other       the heading: ``SSM
                                        paragraphs within the section.              provisions'' for consistency
                                                                                    with the rest of the
                                                                                    paragraphs included in the
                                                                                    section.
40 CFR 63.11498(b)...................  Provision provides an exemption for         Given that in the October 29,
                                        certain wastewater streams during periods   2009, final rule the EPA
                                        of startup and shutdown.                    removed the exemption from
                                                                                    emissions standards for
                                                                                    periods of SSM in accordance
                                                                                    with a decision of the
                                                                                    United States Court of
                                                                                    Appeals for the District of
                                                                                    Columbia Circuit, Sierra
                                                                                    Club v. EPA, 551 F.3d 1019
                                                                                    (D.C. Cir. 2008), cert.
                                                                                    denied, 130 S. Ct. 1735
                                                                                    (U.S. 2010), the EPA is
                                                                                    proposing to remove the
                                                                                    sentence ``The requirements
                                                                                    in Item 2 of table 6 to this
                                                                                    subpart do not apply during
                                                                                    periods of startup or
                                                                                    shutdown.''
40 CFR 63.11500(a)(2)................  Provision contains a cross reference error  The EPA is proposing to
                                        to table 4 in 40 CFR part 63, subpart       correct the reference to
                                        VVVVVV.                                     table 4 with a reference to
                                                                                    table 5.
40 CFR 63.11500(b)...................  Provision refers to certain NSPS but does   The EPA is proposing to add
                                        not include the most recent promulgated     NSPS subparts VVa, VVb,
                                        versions of certain NSPS.                   IIIa, NNNa, and RRRa to
                                                                                    allow owners and operators
                                                                                    to comply with any of the
                                                                                    requirements in these rules
                                                                                    that are at least as
                                                                                    stringent as the
                                                                                    corresponding requirements
                                                                                    in the CMAS NESHAP to
                                                                                    constitute compliance with
                                                                                    the CMAS NESHAP.
40 CFR 63.11501(c)(1)(vii) and (viii)  Certain provisions are specific to          The EPA is proposing to
 and (d)(1) and (8).                    malfunctions and are being clarified to     revise the malfunction and
                                        include any deviation. Also, the            deviation recordkeeping and
                                        deviation reporting provision does not      reporting requirements to
                                        specify all the information to be           clarify what must be
                                        reported.                                   maintained as records and
                                                                                    reported.
40 CFR 63.11501(d)...................  Provision does not specify how to report    The EPA is proposing to
                                        basic facility information.                 clarify that all semiannual
                                                                                    compliance reports must
                                                                                    contain the company name and
                                                                                    address (including county),
                                                                                    as well as the beginning and
                                                                                    ending dates of the
                                                                                    reporting period.
40 CFR 63.11501(d)...................  Provision allows facilities to skip         The EPA is proposing to
                                        semiannual reporting for periods where no   remove this exemption as it
                                        events described by 40 CFR 63.11501(d)(1)-  contradicts the General
                                        (8) occur.                                  Provisions at 40 CFR
                                                                                    63.10(e)(3)(v) and revise
                                                                                    the paragraph to include a
                                                                                    reference to 40 CFR
                                                                                    63.10(e)(3)(v).
40 CFR 63.11501(d)(1)................  Provision does not specify what             The EPA is proposing to
                                        information to collect when a deviation     clarify that owners and
                                        occurs.                                     operators must report the
                                                                                    start date, start time,
                                                                                    duration in hours, cause, a
                                                                                    list of the affected sources
                                                                                    or equipment, an estimate of
                                                                                    the quantity of each
                                                                                    regulated pollutant emitted
                                                                                    over any emission limit, a
                                                                                    description of the method
                                                                                    used to estimate the
                                                                                    emissions, actions taken to
                                                                                    minimize emissions, and any
                                                                                    corrective action taken to
                                                                                    return the affected unit to
                                                                                    its normal or usual manner
                                                                                    of operation for each
                                                                                    deviation from the
                                                                                    standards.
40 CFR 63.11502(b)...................  The definition of ``batch process vent''    The EPA is proposing to
                                        does not consider the impacts of the        update the definition to
                                        proposed EtO standards.                     clarify that the exemption
                                                                                    that ``emission streams from
                                                                                    emission episodes that are
                                                                                    undiluted and uncontrolled
                                                                                    containing less than 50 ppmv
                                                                                    HAP are not part of any
                                                                                    batch process vent'' does
                                                                                    not apply to batch process
                                                                                    vents in EtO service.
40 CFR 63.11502(b)...................  The definition of ``continuous process      The EPA is proposing to
                                        vent'' does not consider the impacts of     clarify that the 0.005
                                        the proposed EtO standards.                 weight percent total organic
                                                                                    HAP criteria at 40 CFR
                                                                                    63.107(d) does not apply for
                                                                                    continuous process vents in
                                                                                    EtO service.

[[Page 7977]]

 
40 CFR 63.11502(b)...................  The definition of ``continuous process      The EPA is proposing to
                                        vent'' improperly relies on the control     replace the references to 40
                                        criteria of the HON as detailed at 40 CFR   CFR 63.107(i) with a similar
                                        63.107(i).                                  provision that relies on the
                                                                                    requirements of table 3 in
                                                                                    40 CFR part 63, subpart
                                                                                    VVVVVV.
40 CFR 63.11502(b)...................  The definition of ``in organic HAP          The EPA is proposing to
                                        service'' does not consider the impact of   revise the definition to
                                        the proposed EtO standards for equipment    specify that any piece of
                                        leaks and the proposed LDAR program for     equipment in EtO service is
                                        all equipment leaks, nor does it consider   also in organic HAP service
                                        that the proposed term for ``heat           and establish that, for the
                                        exchange system'' uses the phrase ``in      proposed LDAR programs
                                        organic HAP service''.                      associated with equipment
                                                                                    and heat exchange systems,
                                                                                    in organic HAP service means
                                                                                    ``that a piece of equipment
                                                                                    or heat exchange system
                                                                                    either contains or contacts
                                                                                    a fluid (liquid or gas) that
                                                                                    is at least 5 percent by
                                                                                    weight of total organic
                                                                                    HAP's as determined
                                                                                    according to the provisions
                                                                                    of 40 CFR 63.180(d).'' The
                                                                                    EPA is also proposing to
                                                                                    clarify that for purposes of
                                                                                    the definition of ``heat
                                                                                    exchange system'', the term
                                                                                    ``equipment'' in Sec.
                                                                                    63.180(d) includes heat
                                                                                    exchange systems.
40 CFR 63.11502(b)...................  The definition of ``process vessel'' is     The EPA is proposing to
                                        contradictory with the definition of        revise the definition of
                                        ``continuous process vent.''                ``process vessel'' to remove
                                                                                    reactors and distillation
                                                                                    units from the list of
                                                                                    provided examples given that
                                                                                    reactors and distillation
                                                                                    units are a source of
                                                                                    continuous process vents
                                                                                    (i.e., some, or all, of a
                                                                                    gas stream originates ``as a
                                                                                    continuous flow from an air
                                                                                    oxidation reactor,
                                                                                    distillation unit, or
                                                                                    reactor during operation of
                                                                                    the chemical manufacturing
                                                                                    process unit'').
40 CFR 63.11502(b)...................  The definition of ``wastewater'' does not   The EPA is proposing to
                                        consider the impact of the proposed EtO     specify that the phrase
                                        standards.                                  ``and that contains at least
                                                                                    5 ppmw of any HAP listed in
                                                                                    table 9 to subpart G of this
                                                                                    part and has an annual
                                                                                    average flow rate of 0.02
                                                                                    liters per minute'' does not
                                                                                    apply to wastewater in
                                                                                    ethylene oxide service.
Table 9 to subpart VVVVVV of Part 63.  Entries include language specific to        The EPA is proposing to
                                        malfunctions.                               revise the entries for
                                                                                    63.10(b)(2)(ii), (c)(10),
                                                                                    (c)(11), and (d)(5) to
                                                                                    reflect the changes to the
                                                                                    malfunction and deviation
                                                                                    recordkeeping and reporting
                                                                                    requirements.
Table 9 to subpart VVVVVV of Part 63.  Entries do not consider EtO specific        The EPA is proposing to
                                        monitoring requirements.                    update table 9 to the CMAS
                                                                                    NESHAP to specify which
                                                                                    General Provisions do not
                                                                                    apply for EtO specific
                                                                                    sources to be consistent
                                                                                    with the proposed EtO
                                                                                    standards.
Various..............................  Rule contains incorrect phrases, does not   The EPA is proposing to make
                                        contain certain phrases, or incorrectly     editorial corrections where
                                        cross references other provisions.          necessary including, but not
                                                                                    limited to, adding missing
                                                                                    words, correcting errors,
                                                                                    updating acronyms, and
                                                                                    correcting cross references.
----------------------------------------------------------------------------------------------------------------

E. What compliance dates are we proposing, and what is the rationale 
for the proposed compliance dates?

    The proposed amendments in this rulemaking for adoption under CAA 
section 112(d)(5) and (6) (see sections IV.A through IV.C of this 
preamble) are subject to the compliance deadlines outlined in the CAA 
under section 112(i). For all the EtO requirements we are proposing 
under CAA section 112(d)(5) (see section IV.A of this preamble), we are 
proposing at 40 CFR 63.11494(l) that existing affected sources and 
affected sources that were new sources under the current CMAS NESHAP 
(i.e., they commenced construction or reconstruction after October 6, 
2008 and on or before January 22, 2025) must comply with all of the 
amendments no later than 2 years after the effective date of the final 
rule or upon startup, whichever is later. For all the non-EtO 
requirements we are proposing under CAA section 112(d)(5) and all the 
requirements we are proposing under CAA section 112(d)(6) (see sections 
IV.B and IV.C of this preamble, respectively), we are proposing at 40 
CFR 63.11494(k) that existing affected sources and affected sources 
that were new sources under the current CMAS NESHAP (i.e., they 
commenced construction or reconstruction after October 6, 2008 and on 
or before January 22, 2025) must comply with all of the amendments no 
later than 3 years after the effective date of the final rule or upon 
startup, whichever is later.
    For fenceline monitoring (see section IV.A.7 of this preamble), we 
are proposing at 40 CFR 63.11494(m) that owners and operators of all 
existing affected sources and all affected sources that were new under 
the current rule (i.e., sources that commenced construction or 
reconstruction after October 6, 2008, and on or before January 22, 
2025) must begin fenceline monitoring 2 years after the effective date 
of the final rule and, starting 3 years after the effective date of the 
final rule, perform root cause analysis and apply corrective action 
requirements upon exceedance of an annual average concentration action 
level.
    For existing sources, CAA section 112(i) provides that the 
compliance date shall be as expeditious as practicable, but no later 
than 3 years after the effective date of the standard (``Section 
112(i)(3)'s three-year maximum compliance period applies generally to 
any emission standard . . . promulgated under [section 112].'' 
Association of Battery Recyclers v. EPA, 716 F.3d 667, 672 (D.C. Cir. 
2013)). In determining what compliance period is as expeditious as 
practicable, we consider the amount of time needed to plan and 
construct projects and change operating procedures. As provided in CAA 
section 112(i) and 5 U.S.C. 801(3), all new affected sources that 
commenced construction or reconstruction after January 22, 2025 would 
be required to comply with these requirements upon the effective date 
of the final rule or upon startup, whichever is later (see proposed 40 
CFR 63.11494(h) and (j)).
1. Rationale for Proposed Compliance Dates of Proposed CAA 
Section112(d)(5) and (6) Amendments
    Many of the GACT requirements that we are proposing under CAA 
section 112(d)(5) address emissions of EtO from equipment leaks, heat 
exchange systems, process vents, storage tanks, and wastewater at CMAS 
processes (see sections IV.A.1 through IV.A.4 of this

[[Page 7978]]

preamble). The proposed provisions will require time to plan, purchase, 
and install equipment for EtO control. For example, for CMAS process 
vents in EtO service (see section IV.A.3 of this preamble for 
additional details), if the affected source cannot demonstrate 99.9 
percent control of EtO emissions, or reduce EtO emissions to less than 
1 ppmv (from each process vent) or 5 lb/yr (for all combined process 
vents), then the owner or operator would need to install a new control 
system, improve their existing control system, or otherwise reduce 
emissions. In addition, we are proposing a suite of operational and 
monitoring requirements for flares that emit EtO (see section IV.A.6 of 
this preamble). We anticipate that the proposed provisions for flares 
that emit EtO (used to control EtO emissions from process vents and 
storage tanks) would require the installation of new monitoring 
equipment, and we project owners and operators would need to install 
new control systems to monitor and adjust assist gas (air or steam) 
addition rates. Similar to the addition of new monitoring equipment and 
control systems, these new monitoring requirements for flares that emit 
EtO would require engineering evaluations, solicitation and review of 
vendor quotes, contracting and installation of the equipment, and 
operator training. Installation of new monitoring and control equipment 
on flares will require the flare to be taken out of service. Depending 
on the configuration of the flares and flare header system, taking the 
flare out of service may also require a significant portion of the CMPU 
to be shutdown. Therefore, we are proposing a compliance date of 2 
years after the publication date of the final rule, or upon startup, 
whichever is later, to comply with the proposed EtO requirements for 
all existing affected sources and all new affected sources under the 
current rules that commenced construction or reconstruction after 
October 6, 2008, and on or before January 22, 2025. For all new 
affected sources that commence construction or reconstruction after 
January 22, 2025, we are proposing owners or operators comply with the 
EtO requirements upon the effective date of the final rule or upon 
startup, whichever is later. We are soliciting comment on whether an 
alternate compliance timeframe (i.e., shorter or longer than the 
proposed 2 years) would be more appropriate for the EtO requirements 
established pursuant to CAA section 112(d)(5).
    Compliance dates for the fenceline monitoring provisions proposed 
under CAA section 112(d)(5) consider the amount of time that it will 
take owners and operators to develop their siting plans and secure the 
capabilities to conduct the monitoring and analyze the results. For 
fenceline monitoring, the compliance timeline also must consider time 
to allow commercial labs to conduct the needed method development, 
expand capacity, and develop the logistics needed to meet the 
requirements in the final rule. In addition, time is needed to read and 
assess the new fenceline monitoring requirements; prepare sampling and 
analysis plans; develop and submit site-specific monitoring plans; 
identify representative, accessible, and secure monitoring locations 
for offsite monitors and obtain permission from the property owner to 
both place and routinely access the monitors; make any necessary 
physical improvements to fencelines to be able to site monitors, 
including construction of access roads, physical fencing, and potential 
drainage improvements; and obtain approval of any necessary capital 
expenditures. Therefore, we are proposing that owners and operators of 
all existing sources and all new affected sources under the current 
rules that commenced construction or reconstruction after October 6, 
2008, and on or before January 22, 2025 must begin fenceline monitoring 
2 years after the publication date of the final rule and must perform 
root cause analysis and apply corrective action requirements upon 
exceedance of an annual average concentration action level starting 3 
years after the publication date of the final rule. For all new 
affected sources that commence construction or reconstruction after 
January 22, 2025, we are proposing that owners or operators begin 
fenceline monitoring upon the effective date of the final rule or upon 
startup, whichever is later. We are also proposing to require quarterly 
reporting of fenceline results beginning 1 year after monitoring begins 
for such sources.
    For PRDs, we are establishing management practices in the CMAS 
NESHAP under CAA section 112(d)(5) that require a process hazard 
analysis and implementation of a minimum of three redundant measures to 
prevent atmospheric releases (see section IV.B.2 of this preamble). 
Alternately, owners or operators may elect to install closed vent 
systems to route these PRDs to a flare, drain (for liquid thermal 
relief valves), or other control system. We anticipate that sources 
will need to identify the most appropriate preventive measures or 
control approach; design, install, and test the system; install 
necessary process instrumentation and safety systems; and may need to 
time installations with equipment shutdown or maintenance outages. 
Therefore, for all existing affected sources, and all new affected 
sources under the current CMAS NESHAP that commenced construction or 
reconstruction after October 6, 2008, and on or before January 22, 
2025, we are proposing a compliance date of 3 years from the 
publication date of the final rule (or upon startup, whichever is 
later) for owners or operators to comply with the management practices 
for atmospheric PRD releases. For all new affected sources that 
commence construction or reconstruction after January 22, 2025, we are 
proposing owners or operators comply with the management practices for 
atmospheric PRD releases upon the effective date of the final rule or 
upon startup, whichever is later.
    Other amendments we are proposing under CAA section 112(d)(5) 
include LDAR requirements for pressure vessels (see section IV.B.1 of 
this preamble). We are also proposing new LDAR requirements under CAA 
section 112(d)(6) for equipment leaks in organic HAP service and heat 
exchange systems with cooling water flow rates greater than 8,000 gpm 
(see section IV.C.1 of this preamble). We project some owners and 
operators would require engineering evaluations, solicitation and 
review of vendor quotes, contracting and installation of monitoring 
equipment, and operator training. In addition, facilities will need 
time to read and understand the amended rule requirements and update 
standard operating procedures. Also, any of these proposed provisions 
may require additional time to plan, purchase, and install equipment 
for emissions control; and even if not, the EPA recognizes the 
confusion that multiple different compliance dates for individual 
requirements would create and the additional burden such an assortment 
of dates would impose. Lastly, other recent rulemakings are requiring 
updates to LDAR provisions for hundreds of sources not previously 
required to do EPA Method 21 monitoring (see the Gasoline Distribution 
NESHAP, 89 FR 39304 May 8, 2024). As such, the demand on contractor 
support may be greater than can be immediately accommodated. Therefore, 
for all existing affected sources, and all new affected sources under 
the current rules that commenced construction or reconstruction after 
October 6, 2008, and on or before January 22, 2025, we are proposing a 
compliance date of 3 years from the publication date of the final rule 
(or upon startup, whichever is

[[Page 7979]]

later) for owners or operators to comply with these other proposed 
amendments. For all new affected sources that commence construction or 
reconstruction after January 22, 2025, we are proposing owners or 
operators comply with these other proposed amendments upon the 
effective date of the final rule or upon startup, whichever is later.
2. Rationale for Proposed Compliance Dates of Other Proposed Amendments
    We are proposing electronic reporting requirements (see section 
IV.D.1 of this preamble), and we anticipate that facilities would need 
some time to successfully accomplish these reporting revisions 
including time to read and understand the amended rule requirements, to 
make any necessary adjustments (including adjusting standard operating 
procedures), and to convert reporting mechanisms and install necessary 
hardware and software. From our assessment of the timeframe needed for 
compliance with the new proposed electronic reporting requirements for 
flare management plans and periodic reports, the EPA considers a period 
of 3 years after the publication date of the final rule to be the most 
expeditious compliance period practicable. Thus, we are proposing that 
all existing affected sources, and all new affected sources under the 
current rule that commenced construction or reconstruction after 
October 6, 2008, and on or before January 22, 2025 be in compliance 
with these revised requirements upon initial startup or within 3 years 
of the publication date of the final rule, whichever is later. For all 
new affected sources that commence construction or reconstruction after 
January 22, 2025, we are proposing owners or operators comply with 
these revised requirements upon the effective date of the final rule or 
upon startup, whichever is later. However, we are proposing at 40 CFR 
63.11496(g)(1)(iv) to provide 60 days after the publication date of the 
final rule (or upon startup, whichever is later) for owners or 
operators of all affected sources to comply with the requirement to 
submit performance test reports electronically following the procedure 
specified in 40 CFR 63.9(k). We are also proposing at 40 CFR 
63.11501(b) to provide 60 days after the publication date of the final 
rule (or upon startup, whichever is later) for owners or operators of 
all affected sources to submit all subsequent Notification of 
Compliance Status reports in PDF format electronically following the 
procedure specified in 40 CFR 63.9(k).

V. Summary of Cost, Environmental, and Economic Impacts

A. What are the affected sources?

    We estimate that there are 251 facilities subject to the CMAS 
NESHAP. There are another 29 facilities that would become subject to 
the rule if EtO were to be added to table 1 to 40 CFR part 63, subpart 
VVVVVV, as proposed. The list of facilities is available in the 
document titled List of Facilities Subject to the CMAS NESHAP, which is 
available in the docket for this rulemaking.

B. What are the air quality impacts?

    This proposed action would reduce HAP and VOC emissions from CMAS 
emission sources. We estimate that the proposed amendments to the 
NESHAP would reduce overall HAP emissions, not including EtO emission 
reductions, from CMAS by approximately 158 tpy. In addition, the EPA 
estimates reductions of approximately 4.6 tpy of EtO emissions based on 
the emissions inventories. With respect to secondary impacts on non-HAP 
pollutants, the EPA estimates that the proposed amendments would reduce 
VOC emissions by 1,557 tpy and on net would reduce emissions of methane 
by 251 tpy.
    The EPA also estimates that the proposed action would result in 
secondary impacts for greenhouse gas emissions and criteria air 
pollutant emissions. The increased electricity and natural gas use to 
power some of the proposed controls would increase emissions of several 
pollutants, including an estimated increase of 36 tpy of carbon 
monoxide (CO), 57,000 tpy of carbon dioxide (CO2), 43 tpy of 
nitrogen oxides (NOX) (including 0.97 tpy of nitrous oxide 
(N2O)), 3 tpy of particulate matter (PM2.5), and 
0.26 tpy of sulfur dioxide (SO2). On net, after accounting 
for the methane emission reductions and the increases in CO2 
and N2O emissions, this proposed rule would increase GHG 
emissions on a CO2-equivalent basis (CO2e) by an 
estimated 50,000 tpy. More information about the estimated emission 
reductions and secondary impacts of this proposed action for the CMAS 
NESHAP can be found in the documents titled Economic Impact Analysis 
and Secondary Impacts for Flares, Thermal Oxidizers, and Wastewater 
Controls for the CMAS NESHAP, which are available in the docket for 
this action; and in documents referenced in sections IV.A through IV.C 
of this preamble. The EPA solicits comments on the quantitative aspects 
of the emissions reductions and secondary impacts of this proposed 
action.

C. What are the cost impacts?

    The EPA estimates the cost of the requirements in this proposed 
action would be approximately $37.6 million (in 2022 dollars for the 
entire period of analysis) in total capital costs and $36.4 million in 
total annual costs (including product recovery), based on our analyses 
of the proposed actions described in sections IV.A through IV.C of this 
preamble. The `total annual costs' are the sum of the annualized 
capital costs and other annual costs (e.g., operating and maintenance 
costs, recordkeeping and reporting costs). To obtain annualized capital 
costs, a capital recovery factor is multiplied by the capital costs. 
The capital recovery factor is based on the lifetime of the capital 
equipment as well as the interest rate. The total annual cost of the 
proposed action without including the value of product recovery is 
estimated to be about $38 million. Thus, product recovery accounts for 
about $1.6 million in annual cost savings, or about four percent of the 
total annual costs without product recovery.

D. What are the economic impacts?

    The economic impacts of this proposal, including the small entity 
impact analysis, are discussed in greater detail in the document titled 
Economic Impact Analysis, which is available in the docket for this 
action.
    As part of fulfilling the analytical requirements of Executive 
Orders 12866 as amended by Executive Order 14094, the EPA presents 
estimates of the present value (PV) of the costs over the 15-year 
analytical period from 2027 to 2041. Costs are in 2022 dollars and 
discounted to 2027 at a two percent discount rate per the 
recommendation in OMB Circular A-4. The EPA also presents the 
equivalent annualized value (EAV) at a two percent discount rate. The 
EAV takes the non-uniform stream of costs (i.e., different costs in 
different years) and converts them into a single annual value that, if 
paid each year from 2027 to 2041, would equal the original stream of 
values in PV terms.
    The PV of the costs over the 15-year period from 2027 to 2041 
without including the value of product recovery is estimated to be $495 
million at a two percent discount rate and the EAV is $38.5 million. 
The PV of the costs including the value of product recovery is 
estimated to be $474 million at a two percent discount rate and the EAV 
is $37 million.
    This proposed action impacts 58 small entities, which own a total 
of 64 CMAS facilities. The EPA evaluates economic impacts of 
rulemakings on

[[Page 7980]]

small entities by examining total annual cost estimates compared to the 
annual revenues of the companies (i.e., entities) that are the ultimate 
owners of the facilities affected by the rule. The EPA estimates cost-
to-sales ratios, which are the total annual costs estimated for each 
entity divided by the entity's annual revenues. This ratio provides a 
measure of the direct economic impact to ultimate owners of CMAS 
facilities.
    The EPA estimates the average cost-to-sales ratio for small 
entities impacted by the proposal will be 0.3 percent with a maximum 
cost-to-sales ratio estimated at 5.5 percent, not considering the value 
of product recovery due to compliance (i.e., the cost savings). With 
product recovery, the EPA estimates that the average cost-to-sales 
ratio for small entities impacted by the proposal will be 0.3 percent 
with a maximum cost-to-sales ratio of 5.4 percent. We estimate that 
about nine percent of impacted small entities (five small entities out 
of a total of 58) will incur total annual costs greater than one 
percent of their annual revenue, and two percent of small entities (one 
small entity in total) will incur total annual costs greater than three 
percent of their annual revenue. The number of entities with a one 
percent or greater cost-to-sales ratio falls to three entities, or five 
percent of all small entities, when the total annual cost estimates 
include the value of product recovery, and one entity has a cost-to-
sales ratio that remains above three percent. The EPA does not 
anticipate that this proposed action will have a substantial impact on 
a significant number of small entities. The EPA also does not expect 
this proposed action to have significant market impacts or employment 
impacts.
    It is important to note that the small entities that own facilities 
affected by the proposed EtO standards have relatively higher estimated 
cost-to-sales ratios, with an average cost-to-sales ratio of 3 percent 
for the three EtO facilities that are owned by small entities. The 
small entity with the maximum cost-to-sales ratio of 5.5 percent owns a 
facility affected by the proposed EtO standards. These three small 
entities also have smaller average annual revenues compared to the 
whole population of small entities, averaging $47 million in annual 
revenues compared to $230 million for all small entities. For 
additional details on the costs of this proposed rulemaking, please see 
the document titled Economic Impact Analysis, available in the docket 
for this action.

E. What are the benefits?

    The EPA did not monetize the benefits from the estimated emission 
reductions of HAP associated with this proposed action. The EPA 
currently does not have sufficient methods to monetize benefits 
associated with HAP reductions and risk reductions for this rulemaking. 
However, we estimate that the final rule amendments would reduce EtO 
emissions by 4.6 tpy and expect that these reductions will lower the 
risk of adverse health effects, including cancer, for individuals in 
communities near CMAS facilities. For additional information on the 
nonmonetized benefits of this rulemaking and a qualitative discussion 
of the health risks associated with exposure to EtO and several other 
HAP, please see the document titled Economic Impact Analysis, available 
in the docket for this action. The EPA solicits comments on the 
benefits of HAP reductions discussed in this section.
    The secondary emissions impacts estimated for this proposed action 
include net reductions in VOC and methane emissions, and increases in 
emissions of PM2.5, SO2, NOX 
(including N2O), CO2, and CO. The EPA was not 
able to monetize the health and environmental impacts associated with 
the estimated changes in criteria air pollutant emissions for this 
proposed rule, which include increased PM2.5 and 
PM2.5 precursor emissions and changes in VOC and 
NOX emissions, which impact the formation of ground-level 
ozone.
    The EPA provided monetized estimates of the impacts associated with 
the methane emissions reductions and the net increases in 
CO2 and N2O emissions using the EPA's social cost 
of greenhouse gas (SC-GHG) estimates. The estimated climate benefits 
are negative on net. The PV of the climate benefits for the 15-year 
period from 2027 to 2041 is estimated to be negative $195 million in 
2022 dollars discounted at a two percent rate, and the EAV is estimated 
to be negative $15 million.

F. What analysis of environmental justice did we conduct?

    For purposes of analyzing regulatory impacts, the EPA relies upon 
its June 2016 ``Technical Guidance for Assessing Environmental Justice 
in Regulatory Analysis,'' which provides recommendations that encourage 
analysts to conduct the highest quality analysis feasible, recognizing 
that data limitations, time, resource constraints, and analytical 
challenges will vary by media and circumstance. The Technical Guidance 
states that a regulatory action may involve potential environmental 
justice (EJ) concerns if it could: (1) create new disproportionate 
impacts on communities with EJ concerns; (2) exacerbate existing 
disproportionate impacts on communities with EJ concerns; or (3) 
present opportunities to address existing disproportionate impacts on 
communities with EJ concerns through this action under development.
    The EPA's EJ technical guidance states that ``[t]he analysis of 
potential EJ concerns for regulatory actions should address three 
questions: (1) Are there potential EJ concerns associated with 
environmental stressors affected by the regulatory action for 
population groups of concern in the baseline? (2) Are there potential 
EJ concerns associated with environmental stressors affected by the 
regulatory action for population groups of concern for the regulatory 
option(s) under consideration? (3) For the regulatory option(s) under 
consideration, are potential EJ concerns created or mitigated compared 
to the baseline?'' \58\
---------------------------------------------------------------------------

    \58\ ``Technical Guidance for Assessing Environmental Justice in 
Regulatory Analysis'', U.S. EPA, June 2016. Quote is from Section 
3--Key Analytic Considerations, page 11.
---------------------------------------------------------------------------

    The EJ analysis is presented for the purpose of providing the 
public with as full as possible an understanding of the potential 
impacts of this proposed action. The EPA notes that analysis of such 
impacts is distinct from the determinations proposed in this action 
under CAA section 112, which are based solely on the statutory factors 
the EPA is required to consider under that section.
    To examine the potential for EJ concerns, the EPA conducted three 
different demographic analyses: a proximity analysis, a baseline cancer 
risk-based analysis (i.e., before implementation of any controls 
required by this proposed action), and a post-control cancer risk-based 
analysis (i.e., after implementation of the controls required by this 
proposed action). The proximity demographic analysis is an assessment 
of individual demographic groups in the total population living within 
10 km (~6.2 miles) and 50 km (~31 miles) of the facilities. The 
baseline risk-based demographic analysis is an assessment of risks to 
individual demographic groups in the population living within 10 km and 
50 km of the facilities prior to the implementation of any controls 
required by this proposed action (``baseline''). The post-control risk-
based demographic analysis is an assessment of risks to individual

[[Page 7981]]

demographic groups in the population living within 10 km and 50 km of 
the facilities after implementation of the controls required by this 
proposed action (``post-control''). The risk-based demographic analyses 
were performed for the following three different HAP emissions 
scenarios (described in sections V.F.1 through V.F.3 of this preamble): 
CMAS categories HAP emissions (10 km and 50 km), CMAS whole-facility 
HAP emissions (10 km and 50 km), and CMAS community HAP emissions (10 
km only).
1. CMAS Categories Demographics
    For the CMAS categories, the EPA examined the potential for the 247 
CMAS facilities (for which the EPA had HAP emissions inventories for 
emissions from the CMAS categories) to pose concerns to communities 
living in proximity to facilities, both in the baseline and under the 
control option established in this proposed action. Specifically, to 
examine the potential for EJ concerns, the EPA conducted three 
different demographic analyses of the populations living within 10 km 
and 50 km of the CMAS facilities: a proximity analysis, baseline cancer 
and noncancer risk-based analyses (i.e., before implementation of any 
controls required by this proposed action), and post-control cancer and 
noncancer risk-based analyses (i.e., after implementation of the 
controls required by this proposed action). In this preamble, we focus 
on the results from the demographic analyses using a 10 km radius 
because this area captures the majority of the population with higher 
cancer risks due to HAP emissions from CMAS facilities. Specifically, 
100 percent of the population with baseline cancer risks greater than 
or equal to 50-in-1 million and with noncancer hazard indices greater 
than 1 from emissions associated with the CMAS categories live within 
10 km of the CMAS facilities. The methodology and detailed results of 
the demographic analysis, including the demographic analyses for 
populations living within 10 km and 50 km of facilities, are presented 
in the document titled Analysis of Demographic Factors for Populations 
Living Near Chemical Manufacturing Area Source (CMAS) Facilities--
Source Category Analysis of Proposed Amendments, which is available in 
the docket for this rulemaking. The following paragraphs briefly 
summarize the results of these demographic analyses.
    For all three demographic analyses, the affected populations (i.e., 
those living within 10 km of the facilities) are compared to the 
national population. The total population, population percentages, and 
population count for each demographic group for the entire U.S. 
population are shown in the column titled ``Nationwide Average for 
Reference'' in tables 11 through 13 of this preamble. These national 
data are provided as a frame of reference to compare the results of the 
proximity analysis, the baseline cancer and noncancer risk-based 
analyses, and the post-control cancer and noncancer risk-based 
analysis. The column titled ``Proximity Analysis for Population living 
within 10 km of CMAS Facilities'' in tables 11 through 13 of this 
preamble shows the share and count of people for each of the 
demographic categories for the total population living within 10 km 
(~6.2 miles) of CMAS facilities. These are the results of the proximity 
analysis and are repeated in tables 11 through 13 of this preamble for 
ease of comparison to the risk-based analyses discussed later.
    The results of the proximity analysis indicate that a total of 33.7 
million people live within 10 km of the 247 CMAS facilities 
analyzed.\59\ The percent of the population living within 10 km of the 
CMAS facilities is above the corresponding national average for the 
following demographic groups: Black, Hispanic or Latino, Other/
Multiracial, people living below the poverty level, people living below 
two times the poverty level, people over the age of 25 without a high 
school diploma, and linguistic isolation. The results of the proximity 
analysis indicate that the proportion of other demographic groups 
living within 10 km of CMAS facilities is similar to or below the 
national average.
---------------------------------------------------------------------------

    \59\ There are 248 CMAS facilities with emissions data specific 
to the categories, however, one facility has no population living 
within 10 km and thus was not included in the EJ analysis.
---------------------------------------------------------------------------

    The baseline cancer risk-based demographic analysis focuses on 
populations that have higher cancer risks. The baseline risk-based 
demographic analysis results are shown in the ``baseline'' column of 
tables 11 through 13 of this preamble. This analysis focused on the 
populations living within 10 km (~6.2 miles) of the CMAS facilities 
with estimated cancer risks greater than or equal to 1-in-1 million 
resulting from emissions from CMAS categories (table 11 of this 
preamble), greater than or equal to 50-in-1 million (table 12 of this 
preamble), and greater than 100-in-1 million (table 13 of this 
preamble).
    The results of the cancer risk-based demographic analysis indicate 
that a total of 2 million people living within 10 km of 76 of the CMAS 
facilities analyzed have a cancer risk greater than or equal to 1-in-1 
million from CMAS HAP emissions. The percent of the population living 
within 10 km of these CMAS facilities with cancer risks greater than or 
equal to 1-in-1 million is above the corresponding national average for 
the following demographic groups: Black, Hispanic or Latino, people 
living below the poverty level, people living below two times the 
poverty level, people over 25 without a high school diploma, and 
linguistic isolation. The percent of the population with cancer risks 
greater than or equal to 1-in-1 million that are Black (25 percent) is 
higher than in the proximity analysis (19 percent) and is approximately 
two times higher than the national average (12 percent). The percent of 
the population with cancer risks greater than or equal to 1-in-1 
million that are Hispanic/Latino (25 percent) is higher than in the 
proximity analysis (21 percent) and the national average (19 percent).
    The results of the cancer risk-based demographic analysis indicate 
that a total of 36,100 people living within 10 km of 15 of the CMAS 
facilities analyzed have cancer risks greater than or equal to 50-in-1 
million from CMAS HAP emissions. The percent of the population living 
within 10 km of these CMAS facilities with cancer risks greater than or 
equal to 50-in-1 million is above the corresponding national average 
for the following demographic groups: Hispanic or Latino, people living 
below the poverty level, people living below two times the poverty 
level, people over 25 without a high school diploma, and linguistic 
isolation. The percent of the population with cancer risks greater than 
or equal to 50-in-1 million that are Black is at the national average 
(12 percent), which is a lower percentage than for the proximity 
analysis (19 percent). The percent of the population with cancer risks 
greater than or equal to 50-in-1 million that are Hispanic/Latino (40 
percent) is about two times that in the proximity analysis (21 percent) 
and the national average (19 percent).
    The results of the cancer risk-based demographic analysis indicate 
that a total of 3,600 people living within 10 km of 4 of the CMAS 
facilities analyzed have a cancer risk greater than 100-in-1 million 
from CMAS HAP emissions. The percent of the population living within 10 
km of these CMAS facilities with cancer risks greater than 100-in-1 
million is above the corresponding national average for the following 
demographic groups: Hispanic or Latino, people living below the poverty

[[Page 7982]]

level, people living below two times the poverty level, and people over 
25 without a high school diploma. The percent of the population with 
cancer risks greater than 100-in-1 million that are Black (5 percent) 
is well below the national average (12 percent). The percent of the 
population with cancer risks greater than 100-in-1 million that are 
Hispanic/Latino (34 percent) is over 1.5 times greater than in the 
proximity analysis (21 percent) and nearly double the national average 
(19 percent).
    The results of the noncancer risk-based demographic analysis 
indicate that a total of 1,500 people living within 10 km of 2 CMAS 
facilities analyzed have a respiratory hazard index greater than 1 from 
CMAS HAP emissions. The percent of the population living within 10 km 
of these CMAS facilities with respiratory hazard index greater than 1 
is above the corresponding national average for the following 
demographic groups: Hispanic or Latino (90 percent for the source 
categories compared to 19 percent nationwide), people living in 
linguistic isolation (15 percent for the source categories compared to 
5 percent nationwide), people 25 years old and older without a high 
school diploma (33 percent for the source categories compared to 12 
percent nationwide), people living below twice the poverty level (44 
percent for the source categories compared to 29 percent nationwide), 
and people living below the poverty level (24 percent for the source 
categories compared to 13 percent nationwide).
    The results of the noncancer risk-based demographic analysis 
indicate that a total of 1,300 people living within 10 km of 2 CMAS 
facilities analyzed have an immunological hazard index greater than 1 
from CMAS HAP emissions. The demographic results indicate that the 
percentage of the population potentially impacted by CMAS emissions is 
greater than its corresponding nationwide percentage for the following 
demographic groups: Hispanic or Latino (90 percent for the source 
category compared to 19 percent nationwide), people living in 
linguistic isolation (16 percent for the source category compared to 5 
percent nationwide), people 25 years old and older without a high 
school diploma (33 percent for the source category compared to 12 
percent nationwide), people living below twice the poverty level (44 
percent for the source category compared to 29 percent nationwide), and 
people living below the poverty level (24 percent for the source 
category compared to 13 percent nationwide).
    The post-control risk-based demographic analysis shows that the 
controls required by this proposed action will notably reduce the 
number of people who are exposed to cancer risks resulting from 
emissions from the CMAS categories at all risk levels. The results of 
the post-control risk-based demographics analysis are in the columns 
titled ``Post-Control'' of tables 11 through 13 of this preamble. At 
greater than or equal to a cancer risk of 1-in-1 million, the number of 
individuals exposed will decrease from 2.1 million to 1.4 million. The 
demographic composition of those individuals exposed to cancer risk 
greater than or equal to 1-in-1 million post-control is similar to the 
demographic composition of the individuals exposed to a cancer risk of 
1-in-1 million at baseline. The number of individuals exposed to cancer 
risk greater than or equal to 50-in-1 million will decrease from 36,100 
to 4,400.
    The percent of the population living within 10 km of these CMAS 
facilities with post-control cancer risks greater than or equal to 50-
in-1 million is above the corresponding national average for the 
following demographic groups: Hispanic or Latino, Age 0-17, people 
living below poverty, people living below two times poverty, those over 
25 without a high school diploma, and linguistic isolation. The percent 
of the population with post-control cancer risks greater than or equal 
to 50-in-1 million that are Hispanic or Latino (66 percent) is over 
three times the national average (19 percent), with 98 percent of this 
Hispanic or Latino population living around two CMAS facilities (one in 
Illinois and one in Kansas).
    After control is implemented, the number of people who are exposed 
to cancer risks greater than 100-in-1 million resulting from emissions 
from the CMAS categories will decrease from 3,600 to zero. Therefore, 
there are no disparities among demographic groups at this risk level. 
The actions of this proposed rulemaking will improve human health of 
current and future populations that live near these facilities.
    The post-control noncancer risk demographic results are the same as 
those for the baseline scenario because the controls being proposed in 
this action do not directly reduce the nickel emissions that drive the 
noncancer risk.

  Table 11--Source Categories: Comparison of Baseline and Post-Control Demographics of Populations With Cancer
 Risk Greater Than or Equal to 1-in-1 Million Living Within 10 km of CMAS Facilities to the National Average and
                                           the Proximity Demographics
----------------------------------------------------------------------------------------------------------------
                                                                                          Cancer risk >=1-in-1
                                                                   Proximity analysis    million within 10 km of
                                                      Nationwide  for total population       CMAS facilities
                 Demographic group                   average for   living within 10 km -------------------------
                                                      reference    of CMAS facilities                   Post-
                                                                                          Baseline     control
----------------------------------------------------------------------------------------------------------------
Total Population...................................         330M                 33.7M         2.1M         1.4M
Number of Facilities...............................  ...........                   247           76           71
----------------------------------------------------------------------------------------------------------------
                                Race and Ethnicity by Percent [Number of People]
----------------------------------------------------------------------------------------------------------------
White..............................................          60%                   49%          45%          40%
                                                          [196M]               [16.7M]       [925K]       [564K]
Black..............................................          12%                   19%          25%          26%
                                                           [40M]                [6.5M]       [513K]       [377K]
American Indian and Alaskan Native.................         0.6%                  0.2%         0.2%         0.2%
                                                          [2.1M]                 [75K]       [4.1K]       [2.5K]
Hispanic or Latino (white and nonwhite)............          19%                   21%          25%          28%
                                                           [63M]                [7.1M]       [514K]       [404K]
Other and Multiracial..............................           9%                   10%           6%           5%
                                                           [29M]                [3.4M]       [119K]        [78K]
----------------------------------------------------------------------------------------------------------------

[[Page 7983]]

 
                                        Age By Percent [Number of People]
----------------------------------------------------------------------------------------------------------------
Age 0 to 17 years..................................          22%                   22%          24%          24%
                                                           [74M]                [7.4M]       [492K]       [339K]
Age 18 to 64 years.................................          62%                   63%          62%          62%
                                                          [203M]               [21.3M]       [1.3M]       [881K]
Age >=65 years.....................................          16%                   15%          14%          14%
                                                           [53M]                  [5M]       [301K]       [205K]
----------------------------------------------------------------------------------------------------------------
                                      Income by Percent [Number of People]
----------------------------------------------------------------------------------------------------------------
Below Poverty Level................................          13%                   14%          15%          17%
                                                           [42M]                [4.7M]       [318K]       [240K]
Below 2x Poverty Level.............................          30%                   31%          36%          39%
                                                          [100M]               [10.4M]       [750K]       [554K]
----------------------------------------------------------------------------------------------------------------
                                     Education by Percent [Number of People]
----------------------------------------------------------------------------------------------------------------
Over 25 and without a High School Diploma..........          12%                   13%          15%          16%
                                                           [38M]                [4.3M]       [306K]       [232K]
----------------------------------------------------------------------------------------------------------------
                              Linguistically Isolated by Percent [Number of People]
----------------------------------------------------------------------------------------------------------------
Linguistically Isolated............................           5%                    6%           6%           7%
                                                           [17M]                [2.1M]       [123K]       [102K]
----------------------------------------------------------------------------------------------------------------
Notes:
 Nationwide population and demographic percentages are based on Census' 2016-2020 American Community
  Survey (ACS) 5-year block group averages. Total population count is based on 2020 Decennial Census block
  population.
 To avoid double counting, the ``Hispanic or Latino'' category is treated as a distinct demographic
  category. A person who identifies as Hispanic or Latino is counted as Hispanic or Latino, regardless of race.
 The number of facilities represents facilities with a cancer MIR above level indicated. When the MIR
  was located at a user assigned receptor at an individual residence and not at a census block centroid, we were
  unable to estimate population and demographics for that facility.
 The sum of individual populations with a demographic category may not add up to total due to rounding.
  K = Thousands, M = Millions.


  Table 12--Source Categories: Comparison of Baseline and Post-Control Demographics of Populations With Cancer
Risk Greater Than or Equal to 50-in-1 Million Living Within 10 km of CMAS Facilities to the National Average and
                                           the Proximity Demographics
----------------------------------------------------------------------------------------------------------------
                                                                                          Cancer risk >=50-in-1
                                                                   Proximity analysis    million within 10 km of
                                                      Nationwide  for total population       CMAS facilities
                 Demographic group                   average for   living within 10 km -------------------------
                                                      reference    of CMAS facilities                   Post-
                                                                                          Baseline     control
----------------------------------------------------------------------------------------------------------------
Total Population...................................         330M                 33.7M          36K         4.4K
Number of Facilities...............................  ...........                   247           15            8
----------------------------------------------------------------------------------------------------------------
                                Race and Ethnicity by Percent [Number of People]
----------------------------------------------------------------------------------------------------------------
White..............................................          60%                   49%          39%          28%
                                                          [196M]               [16.7M]        [14K]       [1.2K]
Black..............................................          12%                   19%          12%           4%
                                                           [40M]                [6.5M]       [4.5K]        [200]
American Indian and Alaskan Native.................         0.6%                  0.2%         0.1%         0.0%
                                                          [2.1M]                 [75K]       [<100]       [<100]
Hispanic or Latino (white and nonwhite)............          19%                   21%          40%          66%
                                                           [63M]                [7.1M]      [14.4K]       [2.9K]
Other and Multiracial..............................           9%                   10%           8%           2%
                                                           [29M]                [3.4M]       [2.9K]       [<100]
----------------------------------------------------------------------------------------------------------------
                                        Age By Percent [Number of People]
----------------------------------------------------------------------------------------------------------------
Age 0 to 17 years..................................          22%                   22%          30%          34%
                                                           [74M]                [7.4M]        [11K]       [1.5K]

[[Page 7984]]

 
Age 18 to 64 years.................................          62%                   63%          60%          59%
                                                          [203M]               [21.3M]        [22K]       [2.6K]
Age >=65 years.....................................          16%                   15%          10%           7%
                                                           [53M]                  [5M]       [3.7K]        [300]
----------------------------------------------------------------------------------------------------------------
                                      Income by Percent [Number of People]
----------------------------------------------------------------------------------------------------------------
Below Poverty Level................................          13%                   14%          21%          23%
                                                           [42M]                [4.7M]       [7.5K]         [1K]
Below 2x Poverty Level.............................          30%                   31%          49%          47%
                                                          [100M]               [10.4M]        [18K]       [2.1K]
----------------------------------------------------------------------------------------------------------------
                                     Education by Percent [Number of People]
----------------------------------------------------------------------------------------------------------------
Over 25 and without a High School Diploma..........          12%                   13%          27%          30%
                                                           [38M]                [4.3M]        [10K]       [1.3K]
----------------------------------------------------------------------------------------------------------------
                              Linguistically Isolated by Percent [Number of People]
----------------------------------------------------------------------------------------------------------------
Linguistically Isolated............................           5%                    6%          13%          11%
                                                           [17M]                [2.1M]       [4.5K]        [500]
----------------------------------------------------------------------------------------------------------------
Notes:
 Nationwide population and demographic percentages are based on Census' 2016-2020 ACS 5-year block group
  averages. Total population count is based on 2020 Decennial Census block population.
 To avoid double counting, the ``Hispanic or Latino'' category is treated as a distinct demographic
  category. A person who identifies as Hispanic or Latino is counted as Hispanic or Latino, regardless of race.
 The number of facilities represents facilities with a cancer MIR above level indicated. When the MIR
  was located at a user assigned receptor at an individual residence and not at a census block centroid, we were
  unable to estimate population and demographics for that facility.
 The sum of individual populations with a demographic category may not add up to total due to rounding.
  K = Thousands, M = Millions.


  Table 13--Source Categories: Comparison of Baseline and Post-Control Demographics of Populations With Cancer
    Risk Greater Than 100-in-1 Million Living Within 10 km of CMAS Facilities to the National Average and the
                                             Proximity Demographics
----------------------------------------------------------------------------------------------------------------
                                                                                          Cancer risk >100-in-1
                                                                   Proximity analysis    million within 10 km of
                                                      Nationwide  for total population       CMAS facilities
                 Demographic group                   average for   living within 10 km -------------------------
                                                      reference    of CMAS facilities                   Post-
                                                                                          Baseline     control
----------------------------------------------------------------------------------------------------------------
Total Population...................................         330M                 33.7M         3.6K            0
Number of Facilities...............................  ...........                   247            4            0
----------------------------------------------------------------------------------------------------------------
                                Race and Ethnicity by Percent [Number of People]
----------------------------------------------------------------------------------------------------------------
White..............................................          60%                   49%          58%           0%
                                                          [196M]               [16.7M]       [2.1K]            0
Black..............................................          12%                   19%           5%           0%
                                                           [40M]                [6.5M]        [200]            0
American Indian and Alaskan Native.................         0.6%                  0.2%         0.1%         0.0%
                                                          [2.1M]                 [75K]       [<100]            0
Hispanic or Latino (white and nonwhite)............          19%                   21%          34%           0%
                                                           [63M]                [7.1M]       [1.2K]            0
Other and Multiracial..............................           9%                   10%           3%           0%
                                                           [29M]                [3.4M]        [100]            0
----------------------------------------------------------------------------------------------------------------
                                        Age By Percent [Number of People]
----------------------------------------------------------------------------------------------------------------
Age 0 to 17 years..................................          22%                   22%          34%           0%
                                                           [74M]                [7.4M]       [1.2K]            0
Age 18 to 64 years.................................          62%                   63%          55%           0%
                                                          [203M]               [21.3M]         [2K]            0
Age >=65 years.....................................          16%                   15%          11%           0%
                                                           [53M]                  [5M]        [400]            0
----------------------------------------------------------------------------------------------------------------

[[Page 7985]]

 
                                      Income by Percent [Number of People]
----------------------------------------------------------------------------------------------------------------
Below Poverty Level................................          13%                   14%          15%           0%
                                                           [42M]                [4.7M]        [500]            0
Below 2x Poverty Level.............................          30%                   31%          42%           0%
                                                          [100M]               [10.4M]       [1.5K]            0
----------------------------------------------------------------------------------------------------------------
                                     Education by Percent [Number of People]
----------------------------------------------------------------------------------------------------------------
 
                                                  * * * * * * *
Over 25 and without a High School Diploma..........          12%                   13%          23%           0%
                                                           [38M]                [4.3M]        [800]            0
----------------------------------------------------------------------------------------------------------------
                              Linguistically Isolated by Percent [Number of People]
----------------------------------------------------------------------------------------------------------------
Linguistically Isolated............................           5%                    6%           5%           0%
                                                           [17M]                [2.1M]        [200]            0
----------------------------------------------------------------------------------------------------------------
Notes:
 Nationwide population and demographic percentages are based on Census' 2016-2020 ACS 5-year block group
  averages. Total population count is based on 2020 Decennial Census block population.
 To avoid double counting, the ``Hispanic or Latino'' category is treated as a distinct demographic
  category. A person who identifies as Hispanic or Latino is counted as Hispanic or Latino, regardless of race.
 The number of facilities represents facilities with a cancer MIR above level indicated. When the MIR
  was located at a user assigned receptor at an individual residence and not at a census block centroid, we were
  unable to estimate population and demographics for that facility.
 The sum of individual populations with a demographic category may not add up to total due to rounding.
  K = Thousands, M = Millions.

2. CMAS NESHAP Whole-Facility Demographics
    As described in section II.E of this preamble and the document 
titled Risk Assessment for the Chemical Manufacturing Area Source 
(CMAS) Source Categories in Support of the 2025 Technology Review for 
the Proposed Rule, which is available in the docket for this 
rulemaking, we assessed the facility-wide (or ``whole-facility'') risks 
as part of a risk assessment for 278 CMAS facilities, accounting for 
HAP emissions from the entire facility and not just those resulting 
from CMAS categories as discussed in the section V.F.1 of this 
preamble.\60\ The whole-facility risk analysis includes all sources of 
HAP emissions at each facility as reported in the emissions inventory 
developed using the NEI (described in section II.C.2 of this proposed 
rule). The following discussion of the whole-facility demographic 
analysis is focused on post-control risks.
---------------------------------------------------------------------------

    \60\ See footnote 60.
---------------------------------------------------------------------------

    The whole-facility demographic analysis is an assessment of 
individual demographic groups in the total population living within 10 
km (~6.2 miles) and 50 km (~31 miles) of the facilities. In this 
preamble, we focus on the results from the demographic analyses using a 
10 km radius because this area captures the majority of the population 
with higher cancer and noncancer risks due to HAP emissions from CMAS 
facilities. Specifically, 100 percent of the population with baseline 
cancer risks greater than or equal to 50-in-1 million and with 
noncancer hazard indices greater than 1 from emissions from the CMAS 
categories live within 10 km of the CMAS facilities. The results of the 
whole-facility demographic analysis for populations living within 10 km 
and 50 km of CMAS facilities are included in the document titled 
Analysis of Demographic Factors for Populations Living Near Chemical 
Manufacturing Area Source (CMAS) Facilities: Whole Facility Analysis of 
Proposed Amendments which is available in the docket for this 
rulemaking.
    The whole-facility demographic analysis post-control results are 
shown in table 14 of this preamble. This analysis focused on the 
populations living within 10 km of the CMAS facilities with estimated 
whole-facility post-control cancer risks greater than or equal to 1-in-
1 million, greater than or equal to 50-in-1 million, and greater than 
100-in-1 million, as well as with estimated whole-facility post-control 
noncancer hazard indices greater than 1. The risk analysis indicated 
that all emissions from the CMAS facilities, after the reductions 
imposed by the proposed rule, expose a total of about 1.65 million 
people living around 80 facilities to a cancer risk greater than or 
equal to 1-in-1 million, 5,600 people living around 10 facilities to a 
cancer risk greater than or equal to 50-in-1 million, and zero people 
to a cancer risk greater than 100-in-1 million. The risk analysis 
indicated that all emissions from the CMAS facilities, after the 
reductions imposed by the proposed rule, expose a total of about 1,700 
people to a respiratory hazard index greater than 1 and about 1,700 
people to an immunological hazard index greater than 1 (both values 
unchanged from baseline).
    When the CMAS whole-facility populations are compared to the CMAS 
categories populations in the post-control scenarios, we see 250,000 
additional people with risks greater than or equal to 1-in-1 million, 
1,200 additional people with risks greater than or equal to 50-in-1 
million, zero additional people with risks greater than 100-in-1 
million, 200 additional people with respiratory hazard indices greater 
than 1, and 200 additional people with immunological hazard indices 
greater than 1.

[[Page 7986]]

    The demographic distribution of the whole-facility population with 
post-control cancer risks greater than or equal to 1-in-1 million is 
almost identical to the distribution of the source category population 
with post-control cancer risks greater than or equal to 1-in-1 million. 
Therefore, the whole-facility population with post-control cancer risks 
greater than or equal to 1-in-1 million has disproportionately high 
representation from Blacks, Hispanics and Latinos, people living below 
the poverty level, people living below two times the poverty level, 
those over 25 without a high school diploma, and those that are 
linguistically isolated.
    The population with post-control cancer risks greater than or equal 
to 50-in-1 million in the whole-facility analysis is almost identical 
to the distribution of the source category population with post-control 
cancer risks greater than or equal to 50-in-1 million. Therefore, the 
whole-facility population with post-control cancer risks greater than 
or equal to 50-in-1 million has disproportionately high representation 
from Hispanics and Latinos, people living below the poverty level, 
people living below two times the poverty level, those over 25 without 
a high school diploma, and those that are linguistically isolated. As 
such, the Hispanic and Latino population is still disproportionately 
represented at 69 percent, which is well above the national average of 
19 percent.
    Based on results from the whole-facility emissions analysis, there 
are zero people with post-control risks greater than 100-in-1 million.
    The population with post-control respiratory hazard indices greater 
than 1 in the whole-facility analysis is almost identical to the 
distribution of the source category population with baseline and post-
control respiratory hazard indices greater than 1. Therefore, the 
whole-facility population with post-control respiratory hazard indices 
greater than 1 has disproportionately high representation from 
Hispanics or Latinos, people living below the poverty level, people 
living below two times the poverty level, those over 25 without a high 
school diploma, and those who are linguistically isolated. As such, the 
Hispanic and Latino population is disproportionately represented at 90 
percent, which is well above the national average of 19 percent, and 
people living below the poverty level are disproportionately 
represented at 24 percent, which is nearly twice the national average 
of 13 percent.
    The population with post-control immunological hazard indices 
greater than 1 in the whole-facility analysis is almost identical to 
the distribution of the source category population with baseline and 
post-control immunological hazard indices greater than 1. Therefore, 
the whole-facility population with post-control immunological hazard 
indices greater than 1 has disproportionately high representation from 
Hispanics or Latinos, people living below the poverty level, people 
living below two times the poverty level, those over 25 without a high 
school diploma, and those who are linguistically isolated. As such, the 
Hispanic and Latino population is disproportionately represented at 90 
percent, which is well above the national average of 19 percent, and 
people living below the poverty level are disproportionately 
represented at 24 percent, which is nearly twice the national average 
of 13 percent.

    Table 14--Whole-Facility: Whole-Facility Post-Control Demographics for CMAS Facilities by Risk Level for
                                  Populations Living Within 10 km of Facilities
----------------------------------------------------------------------------------------------------------------
                                                                             Whole-facility post-control cancer
                                                                            risk for populations within 10 km of
                                                               Nationwide             CMAS facilities
                      Demographic group                       average for --------------------------------------
                                                               reference     >=1-in-1    >=50-in-1    >100-in-1
                                                                             million      million      million
----------------------------------------------------------------------------------------------------------------
Total Population............................................         330M    1,651,083        5,625            0
Number of Facilities........................................  ...........           80           10            0
----------------------------------------------------------------------------------------------------------------
                                Race and Ethnicity by Percent [Number of People]
----------------------------------------------------------------------------------------------------------------
White.......................................................          60%          41%          24%           0%
                                                                   [196M]       [670K]       [1.4K]            0
Black.......................................................          12%          26%           5%           0%
                                                                    [40M]       [436K]        [300]            0
American Indian and Alaskan Native..........................         0.6%         0.2%         0.0%         0.0%
                                                                   [2.1M]         [3K]       [<100]            0
Hispanic or Latino (white and nonwhite).....................          19%          27%          69%           0%
                                                                    [63M]       [450K]         [4K]            0
Other and Multiracial.......................................           9%           6%           1%           0%
                                                                    [29M]        [91K]       [<100]            0
----------------------------------------------------------------------------------------------------------------
                                        Age By Percent [Number of People]
----------------------------------------------------------------------------------------------------------------
Age 0 to 17 years...........................................          22%          24%          33%           0%
                                                                    [74M]       [393K]         [2K]            0
Age 18 to 64 years..........................................          62%          62%          58%           0%
                                                                   [203M]         [1M]       [3.3K]            0
Age >=65 years..............................................          16%          14%           8%           0%
                                                                    [53M]       [234K]        [500]            0
----------------------------------------------------------------------------------------------------------------
                                      Income by Percent [Number of People]
----------------------------------------------------------------------------------------------------------------
Below Poverty Level.........................................          13%          17%          24%           0%
                                                                    [42M]       [281K]       [1.3K]            0

[[Page 7987]]

 
Below 2x Poverty Level......................................          30%          39%          45%           0%
                                                                   [100M]       [637K]       [2.6K]            0
----------------------------------------------------------------------------------------------------------------
                                     Education by Percent [Number of People]
----------------------------------------------------------------------------------------------------------------
Over 25 and without a High School Diploma...................          12%          16%          28%           0%
                                                                    [38M]       [262K]       [1.6K]            0
----------------------------------------------------------------------------------------------------------------
                              Linguistically Isolated by Percent [Number of People]
----------------------------------------------------------------------------------------------------------------
Linguistically Isolated.....................................           5%           7%          11%           0%
                                                                    [17M]       [109K]        [600]            0
----------------------------------------------------------------------------------------------------------------
Notes:
 Nationwide population and demographic percentages are based on Census' 2016-2020 ACS 5-year block group
  averages. Total population count is based on 2020 Decennial Census block population.
 To avoid double counting, the ``Hispanic or Latino'' category is treated as a distinct demographic
  category. A person who identifies as Hispanic or Latino is counted as Hispanic or Latino, regardless of race.
 The number of facilities represents facilities with a cancer MIR above level indicated. When the MIR
  was located at a user assigned receptor at an individual residence and not at a census block centroid, we were
  unable to estimate population and demographics for that facility.
 The sum of individual populations with a demographic category may not add up to total due to rounding.
  K = Thousands, M = Millions.

3. CMAS NESHAP Community Demographics
    As described in section II.E of this preamble and the document 
titled Risk Assessment for the Chemical Manufacturing Area Source 
(CMAS) Source Categories in Support of the 2025 Technology Review for 
the Proposed Rule, which is available in the docket for this 
rulemaking, we assessed the community risks as part of a discretionary 
risk assessment for 278 CMAS facilities.\61\ The community risks 
include HAP emissions from all stationary point sources for which we 
have emissions data within 10 km of the CMAS facilities identified in 
section II.C.1 of this preamble. The following discussion of the 
community risk analysis is focused on post-control risks. This 
community demographic analysis characterizes the remaining risks 
communities face after implementation of the controls required in this 
proposal.
---------------------------------------------------------------------------

    \61\ See footnote 60.
---------------------------------------------------------------------------

    The community demographic analysis is an assessment of individual 
demographic groups in the total population living within 10 km (~6.2 
miles) of the CMAS facilities. The community risk assessment and 
demographics were only conducted at the 10 km radius because, based on 
emissions from the CMAS categories, this distance includes 100 percent 
of the population with cancer risks greater than or equal to 50-in-1 
million. The full results of the community demographic analysis are in 
the document titled Analysis of Demographic Factors for Populations 
Living Near Chemical Manufacturing Area Source (CMAS) Facilities: 
Community-Based Assessment which is available in the docket for this 
rulemaking.
    The community demographic analysis post-control results are shown 
in table 15 of this preamble. The following discussion of the community 
demographic analysis is focused on the populations living within 10 km 
of the CMAS facilities with estimated community post-control cancer 
risks greater than or equal to 1-in-1 million, greater than or equal to 
50-in-1 million, and greater than 100-in-1 million. The risk analysis 
indicated that all emissions from all facilities within 10 km of the 
CMAS facilities, after the reductions imposed by the proposed rule, 
expose a total of about 8 million people living around 242 facilities 
to a cancer risk greater than or equal to 1-in-1 million, 65,000 people 
living around 66 facilities to a cancer risk greater than or equal to 
50-in-1 million, and about 1,900 people living around nine facilities 
to a cancer risk greater than 100-in-1 million.
    When the CMAS community populations are compared to the CMAS 
categories populations in the post-control scenarios, we see 6.6 
million additional people with cancer risks greater than or equal to 1-
in-1 million, 61,000 additional people with cancer risks greater than 
or equal to 50-in-1 million, and 1,900 additional people with cancer 
risks greater than 100-in-1 million.
    The demographic distribution of the community population with 
cancer risks greater than or equal to 1-in-1 million is similar to the 
category population and the whole-facility population with cancer risks 
greater than or equal to 1-in-1 million in the post-control scenario. 
Therefore, the community population with post-control cancer risks 
greater than or equal to 1-in-1 million has disproportionately high 
representation from Blacks, Hispanics and Latinos, people living below 
the poverty level, people living below two times the poverty level, 
those over 25 without a high school diploma, and those living in 
linguistic isolation.
    The population with cancer risks greater than or equal to 50-in-1 
million in the community analysis has a different demographic 
distribution than the source category population with cancer risks 
greater than or equal to 50-in-1 million in the post-control scenario. 
The percent of the population that is Black with risks greater than or 
equal to 50-in-1 million is lower for the community post-control 
analysis (19 percent) versus the category and whole-facility post-
control analyses (26 percent). For the community post-control 
assessment, the percentage of the population with cancer risks greater 
than or equal to 50-in-1 million that is below the poverty level (13 
percent) and below two times the poverty level (27 percent) is equal to 
or below their corresponding national averages (13 percent and 30 
percent, respectively).

[[Page 7988]]

The percentage of the population that is over 25 years old without a 
high school diploma (14 percent) is above the national average (12 
percent) for community post-control population.
    Based on results from the community emissions analysis, there are 
about 1,900 people with post-control cancer risks greater than 100-in-1 
million. The CMAS categories emissions analysis indicated that there 
are no people with post-control cancer risks greater than 100-in-1 
million. The increased cancer risk for most of these 1,900 people is 
driven largely by emissions of chromium VI from non-CMAS facilities 
within 10 km of CMAS facilities.
    The percent of the population in the community analysis with post-
control cancer risks greater than 100-in-1 million that is Black (15 
percent) and Hispanic or Latino (21 percent) are above their 
corresponding national averages (12 percent and 19 percent, 
respectively). The percent of the population in the community analysis 
with a post control cancer risk greater than 100-in-1 million that is 
below the poverty level (14 percent) and below two times the poverty 
level (36 percent) are above their corresponding national averages (13 
percent and 30 percent, respectively). The percent of the population in 
the community analysis with a post control cancer risk greater than 
100-in-1 million that is over 25 years old without a high school 
diploma (21 percent) is above the national average (12 percent).

   Table 15--Community: Community Post-Control Demographics for CMAS Facilities by Risk Level for Populations
                                        Living Within 10 km of Facilities
----------------------------------------------------------------------------------------------------------------
                                                                             Whole-facility post-control cancer
                                                                            risk for populations within 10 km of
                                                               Nationwide             CMAS  facilities
                      Demographic group                       average for --------------------------------------
                                                               reference     >=1-in-1    >=50-in-1    >100-in-1
                                                                             million      million      million
----------------------------------------------------------------------------------------------------------------
Total Population............................................         330M           8M          65K           2K
Number of Facilities........................................  ...........          242           66            9
----------------------------------------------------------------------------------------------------------------
                                Race and Ethnicity by Percent [Number of People]
----------------------------------------------------------------------------------------------------------------
White.......................................................          60%          40%          49%          64%
                                                                   [196M]       [3.2M]        [32K]       [1.2K]
Black.......................................................          12%          22%          19%          15%
                                                                    [40M]       [1.8M]        [12K]        [300]
American Indian and Alaskan Native..........................         0.6%         0.2%         0.3%         0.1%
                                                                   [2.1M]        [16K]        [200]       [<100]
Hispanic or Latino (white and nonwhite).....................          19%          30%          29%          21%
                                                                    [63M]       [2.4M]        [19K]        [400]
Other and Multiracial.......................................           9%           8%           4%           1%
                                                                    [29M]       [654K]       [2.5K]       [<100]
----------------------------------------------------------------------------------------------------------------
                                        Age By Percent [Number of People]
----------------------------------------------------------------------------------------------------------------
Age 0 to 17 years...........................................          22%          23%          25%          25%
                                                                    [74M]       [1.9M]        [16K]        [500]
Age 18 to 64 years..........................................          62%          63%          64%          62%
                                                                   [203M]         [5M]        [42K]       [1.2K]
Age >= 65 years.............................................          16%          14%          11%          13%
                                                                    [53M]       [1.1M]       [7.4K]        [300]
----------------------------------------------------------------------------------------------------------------
                                      Income by Percent [Number of People]
----------------------------------------------------------------------------------------------------------------
Below Poverty Level.........................................          13%          18%          13%          14%
                                                                    [42M]       [1.4M]       [8.6K]        [300]
Below 2x Poverty Level......................................          30%          38%          27%          36%
                                                                   [100M]       [3.1M]        [18K]        [700]
----------------------------------------------------------------------------------------------------------------
                                     Education by Percent [Number of People]
----------------------------------------------------------------------------------------------------------------
Over 25 and without a High School Diploma...................          12%          18%          14%          21%
                                                                    [38M]       [1.4M]       [9.1K]        [400]
----------------------------------------------------------------------------------------------------------------
                              Linguistically Isolated by Percent [Number of People]
----------------------------------------------------------------------------------------------------------------
Linguistically Isolated.....................................           5%           8%           5%           3%
                                                                    [17M]       [598K]       [3.3K]       [<100]
----------------------------------------------------------------------------------------------------------------
Notes:
 Nationwide population and demographic percentages are based on Census' 2016-2020 ACS 5-year block group
  averages. Total population count is based on 2020 Decennial Census block population.
 To avoid double counting, the ``Hispanic or Latino'' category is treated as a distinct demographic
  category. A person who identifies as Hispanic or Latino is counted as Hispanic or Latino, regardless of race.
 The number of facilities represents facilities with a cancer MIR above level indicated. When the MIR
  was located at a user assigned receptor at an individual residence and not at a census block centroid, we were
  unable to estimate population and demographics for that facility.
 The sum of individual populations with a demographic category may not add up to total due to rounding.
  K = Thousands, M = Millions.


[[Page 7989]]

G. What analysis of children's environmental health did we conduct?

    This action proposes to reduce HAP emissions including those 
emissions from EtO. In addition, the EPA's policy on Children's Health 
\62\ also applies to this action. Accordingly, we have evaluated the 
environmental health or safety effects of EtO emissions and exposures 
on children.
---------------------------------------------------------------------------

    \62\ Children's Health Policy available at: https://www.epa.gov/children/childrens-health-policy-and-plan.
---------------------------------------------------------------------------

    Because EtO is mutagenic (i.e., it can act directly on 
deoxyribonucleic acid and cause chromosome damage), children are 
expected to be more susceptible to its harmful effects. To take this 
into account, as part of the risk assessment performed in supported of 
this rulemaking, the EPA followed its guidelines \63\ and applied age-
dependent adjustment factors (ADAFs) to the inhalation unit risk 
estimate for childhood exposures (from birth up to 16 years of age). 
With the ADAF applied to account for greater susceptibility of 
children, the adjusted EtO inhalation unit risk estimate is 5 x 
10-3 per [micro]g/m\3\. It should be noted that because EtO 
is mutagenic, the associated emission reductions proposed in this 
preamble will be particularly beneficial to children. The results of 
the risk assessment are contained in section II.E of this preamble and 
further documented in the risk report Risk Assessment for the Chemical 
Manufacturing Area Source (CMAS) Source Category in Support of the 2025 
Technology Review for the Proposed Rule which is available in the 
docket for this rulemaking.
---------------------------------------------------------------------------

    \63\ U.S. EPA. 2005. Supplemental Guidance for Assessing 
Susceptibility from Early-Life Exposure to Carcinogens. U.S. EPA, 
Washington, DC, EPA/630/R-03/003F. https://www.epa.gov/sites/default/files/201309/documents/childrens_supplement_final.pdf.
---------------------------------------------------------------------------

VI. Request for Comments

    We solicit comments on all aspects of this proposed action. In 
addition to general comments on this proposed action, we are also 
interested in additional data that may improve the risk assessments, 
economic impact analysis, and other analyses including our assumptions 
and estimates discussed in sections IV.A through IV.C of this preamble. 
We are specifically interested in receiving any information and data 
regarding developments, limitations, or related general considerations 
in practices, processes, and control technologies that reduce HAP 
emissions. We solicit comment on the effectiveness of these proposed 
requirements on reducing ethylene oxide emissions, any capital and 
annual costs that we did not account for, the time that is needed to 
come into compliance with the proposed requirements, or any other 
potential barriers to or impacts of imposing these requirements. We 
request comment on additional information on costs, emissions, product 
recovery, and potential broader impacts to markets including impacts 
small businesses and entities. We request comment on how to address the 
non-monetized costs and benefits of the proposed rule. We request 
estimates of any potential loss of production while bringing facilities 
into compliance and forgone returns due to displaced investment.
    We are requesting comments and data on risks and impacts (both 
direct and indirect) of these proposed requirements on specific 
critical industries such as production of active pharmaceutical 
ingredients. We are interested in comments and data around the extent 
of the costs of compliance with the proposed rule to manufacturers of 
pharmaceuticals or other critical medical products, including any 
potential impacts to the public health industrial base, drug shortages, 
or other supply chain issues. We are also interested in proposals for 
alternative mitigation strategies or technologies.
    We request comment on data, methods, and approaches to monetize 
non-fatal cancer, non-cancer health effects, and other benefits of 
reducing exposure to ethylene oxide and other table 1 HAP.
    In addition, we are requesting comment and data on if more frequent 
heat exchange system monitoring periods, namely continued monthly 
monitoring and/or weekly monitoring, are appropriate for CMAS (see 
section IV.A.2 of this preamble). As mentioned in section IV.C.3 of 
this preamble, we also request comment and data on whether the removal 
of the TRE concept is feasible for CMAS facilities. With respect to 
design evaluations and engineering assessments, we are soliciting 
comment and data on whether they are appropriate for demonstrating 
compliance for certain APCDs. Also, we are soliciting comment on 
whether an alternative compliance timeline for the EtO requirements, as 
discussed in section IV.E.1 of this preamble is appropriate.

VII. Statutory and Executive Order Reviews

    Additional information about these statutes and Executive Orders 
can be found at https://www.epa.gov/laws-regulations/laws-and-executive-orders.

A. Executive Order 12866: Regulatory Planning and Review and Executive 
Order 14094: Modernizing Regulatory Review

    This action is a ``significant regulatory action'' as defined in 
Executive Order 12866, as amended by Executive Order 14094. 
Accordingly, the EPA submitted this action to the OMB for Executive 
Order 12866 review. Documentation of any changes made in response to 
the Executive Order 12866 review is available in the docket. The EPA 
conducted an economic impact analysis for this proposal in a document 
titled Economic Impact Analysis, which is available in the docket for 
this action.

B. Paperwork Reduction Act (PRA)

    The information collection activities in this proposed rule have 
been submitted for approval to the OMB under the PRA. The Information 
Collection Request (ICR) document that the EPA prepared has been 
assigned EPA ICR number 2323.09. You can find a copy of the ICR in the 
docket for this rulemaking, and it is briefly summarized here.
    The EPA is proposing amendments to the CMAS NESHAP that revise 
provisions pertaining to emissions from PRDs, pressure vessels, heat 
exchange systems, and equipment leaks. The EPA is also proposing 
requirements pertaining to EtO emissions from process vents, storage 
vessels, heat exchange systems, equipment leaks, and wastewater. In 
addition, the EPA is proposing amendments to the NESHAP for CMAS that 
revise provisions pertaining to emissions during periods of SSM, add 
requirements for electronic reporting of periodic reports and 
performance test results, fenceline monitoring, and make other minor 
clarifications and corrections. This information will be collected to 
ensure compliance with the CMAS NESHAP.
    Respondents/affected entities: Owners or operators of CMAS 
facilities.
    Respondent's obligation to respond: Mandatory (40 CFR part 63, 
subpart VVVVVV).
    Estimated number of respondents: 280.
    Frequency of response: Initially, quarterly, and semiannually.
    Total estimated burden: Average annual recordkeeping and reporting 
burden is 25,300 hours (per year) to comply with the proposed 
amendments in the CMAS NESHAP. Burden is defined at 5 CFR 1320.3(b).
    Total estimated cost: Average annual cost is $25,500,000 (per year) 
which includes $23,000,000 annualized capital and operations and 
maintenance costs,

[[Page 7990]]

to comply with the proposed amendments in the CMAS NESHAP.
    An agency may not conduct or sponsor, and a person is not required 
to respond to, a collection of information unless it displays a 
currently valid OMB control number. The OMB control numbers for the 
EPA's regulations in 40 CFR are listed in 40 CFR part 9.
    Submit your comments on the Agency's need for this information, the 
accuracy of the provided burden estimates, and any suggested methods 
for minimizing respondent burden to the EPA using the docket identified 
at the beginning of this rulemaking. The EPA will respond to any ICR-
related comments in the final rule. You may also send your ICR-related 
comments to OMB's Office of Information and Regulatory Affairs using 
the interface at https://www.reginfo.gov/public/do/PRAMain. Find this 
particular information collection by selecting ``Currently under 
Review--Open for Public Comments'' or by using the search function. OMB 
must receive comments no later than February 21, 2025.

C. Regulatory Flexibility Act (RFA)

    I certify that the proposed rule in this action will not have a 
significant economic impact on a substantial number of small entities 
under the RFA. The small entities subject to the requirements of this 
action are small businesses within the CMAS categories. The Agency has 
determined that the 58 small entities affected by this action may 
experience an average impact of total annual costs being 0.32 percent 
of their annual revenues, not including product recovery, or 0.29 
percent on average when product recovery from compliance is included. 
Five of these 58 small entities are estimated to experience total 
annual costs above one percent of annual revenues when not including 
product recovery (three small entities when product recovery is 
included), and one small entity had estimated annual costs exceeding 
three percent of annual revenues regardless of whether product recovery 
is included. The percentage of impacted small entities estimated to 
experience total annual costs greater than one or three percent of 
their annual revenues is small and therefore this action will not have 
significant impacts on a substantial number of small entities. Details 
of the analysis for the proposed rule are presented in the document 
titled Economic Impact Analysis, which is available in the docket for 
this action.

D. Unfunded Mandates Reform Act (UMRA)

    This action does not contain an unfunded mandate of $100 million or 
more as described in UMRA, 2 U.S.C. 1531-1538, and does not 
significantly or uniquely affect small governments. The costs involved 
in this action are estimated not to exceed $183 million in 2023$ ($100 
million in 1995$ adjusted for inflation using the GDP implicit price 
deflator) or more in any one year.

E. Executive Order 13132: Federalism

    This action does not have federalism implications. It will not have 
substantial direct effects on the states, on the relationship between 
the National Government and the states, or on the distribution of power 
and responsibilities among the various levels of government.

F. Executive Order 13175: Consultation and Coordination With Tribal 
Governments

    This action has tribal implications. However, it will neither 
impose substantial direct compliance costs on federally recognized 
Tribal governments, nor preempt tribal law. We have identified two 
facilities located on Tribal lands that will potentially be impacted by 
this rulemaking, one of which emits EtO. Consistent with the EPA Policy 
on Coordination and Consultation with Indian Tribes, the EPA will 
provide tribal officials the opportunity to provide meaningful and 
timely input early in the development of this action through multiple 
outreach activities such as Tribal partnership calls, webinars, and 
offers for government-to-government consultation with potentially 
impacted Tribes and other Tribes as requested.

G. Executive Order 13045: Protection of Children From Environmental 
Health Risks and Safety Risks

    Executive Order 13045 directs federal agencies to include an 
evaluation of the health and safety effects of the planned regulation 
on children in federal health and safety standards and explain why the 
regulation is preferable to potentially effective and reasonably 
feasible alternatives. This action is not subject to Executive Order 
13045 because it is not a significant regulatory action under section 
3(f)(1) of Executive Order 12866, though the EPA believes the safety 
risks addressed by this action do present a disproportionate risk to 
children. This action's assessments of potential impacts to human 
health are contained in section II.E of this preamble and in greater 
detail in the document titled Risk Assessment for the Chemical 
Manufacturing Area Source (CMAS) Source Categories in Support of the 
2025 Technology Review for the Proposed Rule, which is available in the 
docket for this rulemaking. In addition, the EPA's Policy on Children's 
Health applies to this action. Information on how the Policy was 
applied is available in section V.G of this preamble.

H. Executive Order 13211: Actions Concerning Regulations That 
Significantly Affect Energy Supply, Distribution, or Use

    This action is not a ``significant energy action'' because it is 
not likely to have a significant adverse effect on the supply, 
distribution, or use of energy. The overall economic impact of this 
proposed rule should be minimal for CMAS and their parent companies 
(which are engaged in the energy sector).

I. National Technology Transfer and Advancement Act (NTTAA) and 1 CFR 
Part 51

    This proposed action involves technical standards. Therefore, the 
EPA conducted searches for the CMAS NESHAP through the Enhanced 
National Standards Systems Network Database managed by the American 
National Standards Institute. We also conducted a review of voluntary 
consensus standards (VCS) organizations and accessed and searched their 
databases. We conducted searches for EPA Methods 5, 5D, 21, and 29 of 
40 CFR part 60, appendix A. During the EPA's VCS search, if the title 
or abstract (if provided) of the VCS described technical sampling and 
analytical procedures that are similar to the EPA's reference method, 
the EPA ordered a copy of the standard and reviewed it as a potential 
equivalent method. We reviewed all potential standards to determine the 
practicality of the VCS for this rulemaking. This review requires 
significant method validation data that meet the requirements of EPA 
Method 301 for accepting alternative methods or scientific, 
engineering, and policy equivalence to procedures in the EPA reference 
methods. The EPA may reconsider determinations of impracticality when 
additional information is available for particular VCS.
    We did not identify any applicable voluntary consensus standards 
for EPA Methods 5D and 21. However, the EPA proposes to incorporate by 
reference VCS ASTM D6784-24, ``Standard Test Method for Elemental, 
Oxidized, Particle-Bound and Total Mercury Gas Generated from Coal-
Fired Stationary

[[Page 7991]]

Sources (Ontario Hydro Method)'' as an acceptable alternative to EPA 
Method 29 (referenced in the CMAS NESHAP at 40 CFR 63.11496(f)(3)(iii)) 
with the following caveats. This ASTM procedure has been approved by 
the EPA as an alternative to EPA Method 29 only when the target 
compound is mercury; and applies to concentrations approximately 0.5 to 
100 [micro]g/m\3\. This test method was developed initially for the 
measurement of mercury in coal-fired power plants; however, it has also 
been extensively used on other stationary combustion sources including 
sources having a flue gas composition with high levels of hydrochloric 
acid and low levels of sulfur dioxide. The test method includes 
equipment and procedures for obtaining samples from effluent ducts and 
stacks, equipment and procedures for laboratory analysis, and 
procedures for calculating results of elemental, oxidized, particle-
bound, and total mercury emissions. ASTM D6784-24 is available at ASTM 
International, 1850 M Street NW, Suite 1030, Washington, DC 20036. See 
https://www.astm.org/. The standard is available to everyone at a cost 
determined by the ASTM ($90). The ASTM also offers memberships or 
subscriptions that allow unlimited access to their methods. The cost of 
obtaining these methods is not a significant financial burden, making 
the methods reasonably available to stakeholders.
    While the EPA identified 7 other VCS as being potentially 
applicable, the Agency decided not to use them because these methods 
are impractical as alternatives because of the lack of equivalency, 
documentation, validation data and other important technical and policy 
considerations. The EPA documented the search and review results in the 
document titled Voluntary Consensus Standard Results for Technology 
Review of the National Emissions Standards for Hazardous Air Pollutants 
for Chemical Manufacturing Area Sources, which is available in the 
docket for this rulemaking. Additional information for the VCS search 
and determinations can be found in this document. The EPA welcomes 
comments on this aspect of the proposed rulemaking and, specifically, 
invites the public to identify potentially applicable VCS and to 
explain why such standards should be used in this regulation.

J. Executive Order 12898: Federal Actions To Address Environmental 
Justice in Minority Populations and Low-Income Populations and 
Executive Order 14096: Revitalizing Our Nation's Commitment to 
Environmental Justice for All

    The EPA believes that the human health or environmental conditions 
that exist prior to this action result in or have the potential to 
result in disproportionate and adverse human health or environmental 
effects on communities with EJ concerns. For this rulemaking, we 
conducted a proximity demographic analysis as well as baseline and 
post-control demographic risk analyses for the source category and 
whole facility. The analysis identified that 33.7 million people live 
within 10 km of the 247 CMAS facilities analyzed. The percent of the 
population living within 10 km of the CMAS facilities is above the 
corresponding national average for the following demographic groups: 
Black, Hispanic or Latino, Other/Multiracial, people living below the 
poverty level, people living below two times the poverty level, people 
over the age of 25 without a high school diploma, and linguistic 
isolation. More details on this analysis are provided in section V.F.1 
of this preamble.
    For existing sources, the EPA believes that this action is likely 
to reduce existing disproportionate and adverse effects on communities 
with EJ concerns. Groups experiencing baseline disparities are expected 
to see reduced exposures due to the proposed level of control for those 
processes emitting EtO and proposed management practices to control 
fugitive emissions from sources of HAP. In addition, this action 
proposes fenceline monitoring for EtO to ensure proper function of 
those management practices. If the proposed changes are implemented, we 
expect no people would be exposed to cancer risk levels greater than 
100-in-1 million due to emissions from the CMAS categories. However, 
for individuals exposed to cancer risk less than 100-in-1 million, 
disparities remain in the proportion of different groups facing 
elevated risk. The controls proposed for this action do not reduce the 
risk of noncancer health impacts and thus the disparities remain the 
same. For more information on the controls proposed in this action, 
please refer to sections IV.A through IV.D of this preamble.
    For new sources, the EPA believes that it is not practicable to 
assess whether this action is likely to result in new disproportionate 
and adverse effects on communities with EJ concerns, because it is not 
possible to know the location of any future new sources.
    The information supporting this Executive Order review is contained 
in section V.F of this preamble.

List of Subjects in 40 CFR Part 63

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

Jane Nishida,
Acting Administrator.
[FR Doc. 2025-00685 Filed 1-21-25; 8:45 am]
BILLING CODE 6560-50-P`