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

Federal RegisterJan 22, 2025

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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.

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: a-and-r-docket@epa.gov.

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:

gallagher.william@epa.gov.

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

SPPDpublichearing@epa.gov.

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

SPPDpublichearing@epa.gov.

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

SPPDpublichearing@epa.gov

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

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

oaqpscbi@epa.gov

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

oaqpscbi@epa.gov

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

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

nitrogen oxides

O nitrous oxide

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

2.5

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

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)

µg/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-

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

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.

See 74 FR 56008, October 29, 2009.

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.

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.

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).

The review is available at

https://iris.epa.gov/static/pdfs/1025tr.pdf.

The report is available at

https://www.epaoig.gov/sites/default/files/2021-05/documents/_epaoig_20210506-21-p-0129.pdf.

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.

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).

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

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.

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).

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

operate a chemical manufacturing process that produces a material or a family of materials described by NAICS code 325.

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.

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,

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

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:

Feedstocks are reactants, solvents, or any other additives to the process.

“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

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)

. 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.

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.

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).

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.

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,

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

Chemical Manufacturers,

which is available in the docket for this rulemaking.

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.

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.

This section summarizes the results of those analyses.

The report is available at

https://www.epaoig.gov/sites/default/files/2021-05/documents/_epaoig_20210506-21-p-0129.pdf.

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

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

Risk assessment

Number of facilities

Maximum individual cancer

risk (-in-1

million)

Estimated population at increased risk of cancer

>100-in-1

million

≥1-in-1 million

Estimated

annual cancer

incidence

(cases per year)

Maximum chronic noncancer TOSHI

Refined maximum screening acute noncancer HQ

Baseline (Pre-Control) Actual Emissions

Source Category

248

800

3,600 (10 km)

3,600 (50 km)

2 million (10 km)

4.4 million (50 km)

0.2 (10 km)

0.4 (50 km)

3 (respiratory, immunological)

Facility-wide

279

800

3,600 (10 km)

3,600 (50 km)

2.2 million (10 km)

4.6 million (50 km)

0.2 (10 km)

0.4 (50 km)

3 (respiratory, immunological)

—

Community-based

9,932

5,000

5,600 (10 km)

8.6 million (10 km)

0.8 (10 km)

Post-Control Emissions

Source Category

248

100

1.3 million (10 km)

2.3 million (50 km)

0.1 (10 km)

0.2 (50 km)

3 (respiratory, immunological)

Facility-wide

279

100

1.4 million (10 km)

2.5 million (50 km)

0.1 (10 km)

0.2 (50 km)

3 (respiratory, immunological)

Community-based

9,932

5,000

1,900 (10 km)

8 million (10 km)

0.6 (10 km)

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.

Maximum individual excess lifetime cancer risk due to HAP emissions.

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.

“—” Indicates where an assessment was not conducted.

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

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.

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.

Natural Resources Defense Council

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).

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

Control option

Total capital investment

($)

Total annualized costs w/o recovery credits

($/yr)

Total annualized costs with recovery credits

($/yr)

VOC emission

reductions

(tpy)

EtO emission

reductions

(tpy)

EtO cost

effectiveness

w/o recovery

credits

($/ton)

EtO cost

effectiveness

with recovery

credits

($/ton)

511,000

1,261,000

1,129,400

146

15,100

13,500

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 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

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.

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.

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

Control option

Total capital

investment

($)

Total

annualized

costs w/o

recovery credits

($/yr)

Total annualized costs with recovery credits

($/yr)

VOC emission

reductions

(tpy)

EtO emission

reductions

(tpy)

EtO cost

effectiveness

w/o recovery

credits

($/ton)

EtO cost

effectiveness

with recovery

credits

($/ton)

EtO Incremental

cost effectiveness

with recovery

credits

(from option 1)

($/ton)

122,000

157,000

117,900

43.4

24.8

6,300

4,700

122,000

359,400

319,500

44.3

25.3

14,200

12,500

388,500

122,000

1,371,500

1,331,300

44.7

25.5

52,300

52,200

1,688,800

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

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

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.

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)

and is within the range of historic cost-effectiveness values that have been accepted for highly toxic HAP (such as hexavalent chromium).

EtO is similarly toxic due to its potency as a carcinogen. As such, we find that this Control Option is cost effective.

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.

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.

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

Control

option

Total capital

investment

($)

Total

annualized costs

($/yr)

EtO emission

reductions

(tpy)

EtO cost

effectiveness

($/ton)

1,395,000

2,126,000

1.1

1,933,000

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

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

in table 9 to subpart G of the HON).

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.

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

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)

, and is within the range of historic cost-effectiveness values that have been accepted for highly toxic HAP (such as hexavalent chromium).

EtO is similarly toxic due to its potency as a carcinogen. As such, we find that this Control Option is cost effective.

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.

See footnote 19.

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

Control option

Total capital

investment

($)

Total

annualized costs

($/yr)

EtO emission

reductions

(tpy)

EtO cost

effectiveness

($/ton)

12,899,400

5,471,300

8.3

659,200

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 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 § 63.145(b) and in accordance with the Group 1 wastewater stream requirements of §§ 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

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.

The results of the impact estimates are summarized in table 6 of this preamble for Control Option 1. See the document titled

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)

and is within range of historic cost-effectiveness values that have been accepted for highly toxic HAP (such as hexavalent chromium).

EtO is similarly toxic due to its potency as a carcinogen. As such, we find that this Control Option is cost-effective.

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.

See footnote 19.

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

Control option

Total capital

investment

($)

Total

annualized costs

($/yr)

VOC emission

reductions

(tpy)

EtO emission

reductions

(tpy)

EtO cost

effectiveness

($/ton)

3,770,000

960,000

12.8

1.56

606,700

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

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 Δc. This approach subtracts the estimated contributions from background emissions that do not originate from the facility. The owner or operator would average the Δc for the most recent year of samples (73 sampling periods) to calculate an annual average Δc on a rolling basis (

i.e.,

calculate a new annual average Δc every 5 days using data from the most recent 73 sampling periods). The owner or operator would compare this rolling annual average Δc 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 (µg/m

) based on three times the representative detection limit (RDL) for EtO.

If the annual average Δc 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 Δc 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 Δc 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 Δc 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 Δc 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 Δc 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 Δc 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,

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

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.

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.

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 µg/m

, 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 µg/m

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

Number of

CMAS

facilities

impacted

Total

capital

investment

($)

Total

annualized

costs

($/yr)

488,000

20,990,000

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.

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.

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.

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

from the work practice standards for PRD releases (see 85 FR 49084, August 12, 2020, and 89 FR 42932, May 16, 2024, respectively).

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,

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.

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

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;

(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.

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

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

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

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

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.

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.

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

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