Standards of Performance for New, Reconstructed, and Modified Sources and Emissions Guidelines for Existing Sources: Oil and Natural Gas Sector Climate Review

Federal RegisterDec 6, 2022

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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 60

[EPA-HQ-OAR-2021-0317; FRL-8510-04-OAR]

RIN 2060-AV16

Standards of Performance for New, Reconstructed, and Modified Sources and Emissions Guidelines for Existing Sources: Oil and Natural Gas Sector Climate Review

AGENCY:

Environmental Protection Agency (EPA).

ACTION:

Supplemental notice of proposed rulemaking.

SUMMARY:

The EPA is issuing this supplemental proposal to update, strengthen, and expand the standards proposed on November 15, 2021 (November 2021 proposal), which are intended to significantly reduce emissions of greenhouse gases (GHGs) and other harmful air pollutants from the Crude Oil and Natural Gas source category. First, the EPA proposes standards for certain sources that were not addressed in the November 2021 proposal. Second, the EPA proposes revisions that strengthen standards for sources of leaks, provide greater flexibility to use innovative advanced detection methods, and establish a super emitter response program. Third, the EPA proposes to modify and refine certain elements of the proposed standards in response to information submitted in public comments on the November 2021 proposal. Finally, the EPA proposes details of the timelines and other implementation requirements that apply to states to limit methane pollution from existing designated facilities in the source category under the Clean Air Act (CAA).

DATES:

Comments.

Comments must be received on or before February 13, 2023. Under the Paperwork Reduction Act (PRA), OMB is required to make a decision concerning the collections of information contained in the proposed rule between 30 and 60 days after publication and submission to OMB. A comment to OMB is best assured of consideration if the Office of Management and Budget (OMB) receives it on or before January 5, 2023.

Public hearing.

The EPA will hold a virtual public hearing on January 10, 2023, and January 11, 2023. See

SUPPLEMENTARY INFORMATION

for information on the hearing.

ADDRESSES:

You may send comments, identified by Docket ID No. EPA-HQ-OAR-2021-0317 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-2021-0317 in the subject line of the message.

•

Fax:

(202) 566-9744. Attention Docket ID No. EPA-HQ-OAR-2021-0317.

•

Mail:

U.S. Environmental Protection Agency, EPA Docket Center, Docket ID No. EPA-HQ-OAR-2021-0317, 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 “Public Participation” heading of the

SUPPLEMENTARY INFORMATION

section of this document. For further information on EPA Docket Center services and the current status, please visit us online at

https://www.epa.gov/dockets.

FOR FURTHER INFORMATION CONTACT:

For questions about this proposed action, contact Ms. Karen Marsh, Sector Policies and Programs Division (E143-05), Office of Air Quality Planning and Standards, U.S. Environmental Protection Agency, Research Triangle Park, North Carolina 27711; telephone number: (919) 541-1065; fax number: (919) 541-0516; and email address:

marsh.karen@epa.gov

or Ms. Amy Hambrick, Sector Policies and Programs Division (E143-05), Office of Air Quality Planning and Standards, Environmental Protection Agency, Research Triangle Park, North Carolina 27711; telephone number: (919) 541-0964; fax number: (919) 541-0516; email address:

hambrick.amy@epa.gov.

SUPPLEMENTARY INFORMATION:

Participation in virtual public hearing.

The public hearing will be held via virtual platform on January 10, 2023, and January 11, 2023, and will convene at 10:00 a.m. Eastern Time (ET) and conclude at 8:00 p.m. ET each day. On each hearing day, 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 announce further details at

https://www.epa.gov/controlling-air-pollution-oil-and-natural-gas-industry.

If the EPA receives a high volume of registrations for the public hearing, we may continue the public hearing on January 12, 2023. The EPA does not intend to publish a document in the

Federal Register

announcing the potential addition of a third day for the public hearing or any other updates to the information on the hearing described in this document. Please monitor

https://www.epa.gov/controlling-air-pollution-oil-and-natural-gas-industry

for any updates to the information described in this document, including information about the public hearing. For information or questions about the public hearing, please contact the public hearing team at (888) 372-8699 or by email at

SPPDpublichearing@epa.gov.

The EPA will begin pre-registering speakers for the hearing no later than 1 business day following the publication of this document in the

Federal Register

. The EPA will accept registrations on an individual basis. To register to speak at the virtual hearing, follow the directions at

https://www.epa.gov/controlling-air-pollution-oil-and-natural-gas-industry

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 January 5, 2023. Prior to the hearing, the EPA will post a general agenda that will list pre-registered speakers in approximate order at:

https://www.epa.gov/controlling-air-pollution-oil-and-natural-gas-industry.

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 provide the EPA with a copy of their oral testimony by submitting the text of your 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.

If you require the services of an interpreter or a special accommodation

such as audio description, please pre-register for the hearing with the public hearing team and describe your needs by December 13, 2022. 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-2021-0317. 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-2021-0317. 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 statute. 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 the

Instructions

section of this document. 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 OAQPS CBI Office at the email address

oaqpscbi@epa.gov,

and as described in the preceding paragraph, 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: OAQPS Document Control Officer (C404-02), OAQPS, U.S. Environmental Protection Agency, Research Triangle Park, North Carolina 27711, Attention Docket ID No. EPA-HQ-OAR-2021-0317. 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.

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:

AMEL alternate means of emissions limitation

ANSI American National Standards Institute

APA Administrative Procedures Act

API American Petroleum Institute

ASME American Society of Mechanical Engineers

ASTM American Society for Testing and Materials

AVO audio, visual, and olfactory

AWP alternative work practice

BMP best management practices

boe barrels of oil equivalents

BSER best system of emission reduction

Btu/scf British thermal unit per standard cubic foot

°C degrees Centigrade

CAA Clean Air Act

CBI Confidential Business Information

CCR Code of Colorado Regulations

CDX EPA's Central Data Exchange

CEDRI Compliance and Emissions Data Reporting Interface

CFR Code of Federal Regulations

methane

CO carbon monoxide

carbon dioxide

Eq. carbon dioxide equivalent

CRA Congressional Review Act

CVS closed vent systems

CWA Clean Water Act

D.C. Circuit U.S. Court of Appeals for the District of Columbia Circuit

DOE Department of Energy

EAV equivalent annual value

EDF Environmental Defense Fund

EG emission guidelines

EIA U.S. Energy Information Administration

EJ environmental justice

E.O. Executive Order

EPA Environmental Protection Agency

ESD emergency shutdown devices

°F degrees Fahrenheit

FEAST Fugitive Emissions Abatement Simulation Toolkit

FR Federal Register

FRFA final regulatory flexibility analysis

g/hr grams per hour

GHG greenhouse gas

GHGI Inventory of U.S. Greenhouse Gas Emissions and Sinks

GHGRP Greenhouse Gas Reporting Program

HAP hazardous air pollutant(s)

ICR information collection request

IRFA initial regulatory flexibility analysis

IWG Interagency Working Group on the Social Cost of Greenhouse Gases

kg kilograms

low-e low emission

LDAR leak detection and repair

Mcf thousand cubic feet

METEC Methane Emissions Technology Evaluation Center

MW megawatt

NAAQS National Ambient Air Quality Standards

NAICS North American Industry Classification System

NDE no detectable emissions

NESHAP National Emissions Standards for Hazardous Air Pollutants

NGO non-governmental organization

NHV net heating value

nitrogen oxides

NSPS new source performance standards

NTTAA National Technology Transfer and Advancement Act

OAQPS Office of Air Quality Planning and Standards

OGI optical gas imaging

OMB Office of Management and Budget

2.5

particulate matter with a diameter of 2.5 micrometers or less

ppm parts per million

PRA Paperwork Reduction Act

PTE potential to emit

PV present value

REC reduced emissions completion

RFA Regulatory Flexibility Act

RIA regulatory impact analysis

RULOF remaining useful life and other factors

SBAR Small Business Advocacy Review

SC-CH

social cost of methane

SC-GHG social cost of greenhouse gases

scf standard cubic feet

scfh standard cubic feet per hour

scfm standard cubic feet per minute

SIP state implementation plan

sulfur dioxide

SPeCS State Planning Electronic Collaborative System

tpy tons per year

the court U.S. Court of Appeals for the District of Columbia Circuit

TAR Tribal Authority Rule

TIP tribal implementation plan

TSD technical support document

UMRA Unfunded Mandates Reform Act

U.S. United States

VCS Voluntary Consensus Standards

VOC volatile organic compounds

VRU vapor recovery unit

Organization of this document.

The information in this preamble is organized as follows:

I. Executive Summary

A. Purpose of the Regulatory Action

B. Summary of the Major Provisions of This Regulatory Action

C. Costs and Benefits

II. General Information

A. Does this action apply to me?

B. How do I obtain a copy of this document, background information, other related information?

III. Purpose of This Regulatory Action

A. What is the purpose of this supplemental proposal?

B. What date defines a new, modified, or reconstructed source for purposes of the proposed NSPS OOOOb?

C. What date defines an existing source for purposes of the proposed EG OOOOc?

D. How will the proposed EG OOOOc impact sources already subject to NSPS KKK, NSPS OOOO, or NSPS OOOOa?

E. How does the EPA consider costs in this supplemental proposal?

F. Legal Basis for Rulemaking Scope

G. Inflation Reduction Act

IV. Summary and Rationale for Changes to the Proposed NSPS OOOOb and EG OOOOc

A. Fugitive Emissions From Well Sites, Centralized Production Facilities, and Compressor Stations

B. Advanced Methane Detection Technologies

C. Super-Emitter Response Program

D. Pneumatic Controllers

E. Pneumatic Pumps

F. Wells and Associated Operations

G. Centrifugal Compressors

H. Combustion Control Devices

I. Reciprocating Compressors

J. Storage Vessels

K. Covers and Closed Vent Systems

L. Equipment Leaks at Natural Gas Processing Plants

M. Sweetening Units

N. Recordkeeping and Reporting

V. Supplemental Proposal for State, Tribal, and Federal Plan Development for Existing Sources

A. Overview

B. Establishing Standards of Performance in State Plans

C. Components of State Plan Submission

D. Timing of State Plan Submissions and Compliance Times

VI. Use of Optical Gas Imaging in Leak Detection (Appendix K)

A. Overview of the November 2021 Proposal

B. Significant Changes Since Proposal

C. Summary of Proposed Requirements

VII. Impacts of This Proposed Rule

A. What are the air impacts?

B. What are the energy impacts?

C. What are the compliance costs?

D. What are the economic and employment impacts?

E. What are the benefits of the proposed standards?

VIII. Statutory and Executive Order Reviews

A. Executive Order 12866: Regulatory Planning and Review and Executive Order 13563: Improving Regulation and Regulatory Review

B. Paperwork Reduction Act (PRA)

C. Regulatory Flexibility Act (RFA)

D. Unfunded Mandates Reform Act (UMRA)

E. Executive Order 13132: Federalism

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

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

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

I. National Technology Transfer and Advancement Act (NTTAA)

J. Executive Order 12898: Federal Actions To Address Environmental Justice in Minority Populations and Low-Income Populations

I. Executive Summary

A. Purpose of the Regulatory Action

On November 15, 2021, the EPA published a proposed rule (November 2021 proposal) that was intended to mitigate climate-destabilizing pollution and protect human health by reducing greenhouse gas (GHG) and VOC emissions from the Oil and Natural Gas Industry,

specifically the Crude Oil and Natural Gas source category.

A wide range of stakeholders, as well as state and tribal governments, submitted public comments on the November 2021 proposal. Over 470,000 public comments were submitted. Many commenters representing diverse perspectives expressed general support for the proposal and requested that the EPA further strengthen the proposed standards and make them more comprehensive. Other commenters highlighted implementation or cost concerns related to elements of the November 2021 proposal or provided specific data and information that the EPA was able to use to refine or revise several of the standards included in the November 2021 proposal.

The EPA characterizes the Oil and Natural Gas Industry operations as being generally composed of four segments: (1) Extraction and production of crude oil and natural gas (“oil and natural gas production”), (2) natural gas processing, (3) natural gas transmission and storage, and (4) natural gas distribution.

The EPA defines the Crude Oil and Natural Gas source category to mean: (1) Crude oil production, which includes the well and extends to the point of custody transfer to the crude oil transmission pipeline or any other forms of transportation; and (2) natural gas production, processing, transmission, and storage, which include the well and extend to, but do not include, the local distribution company custody transfer station, commonly referred to as the “city-gate.”

In the November 2021 proposal, the EPA proposed new standards and emission guidelines under CAA section 111 which would be included in 40 CFR part 60 at subpart OOOOb (NSPS OOOOb) and subpart OOOOc (EG OOOOc). The purpose of this supplemental proposed rulemaking is to strengthen, update, and expand the proposed standards for certain emissions sources, including: (1) To reduce emissions from the source category more comprehensively by adding proposed standards for certain sources that were not addressed in the November 2021 proposal, revising the

proposed requirements for fugitive emissions monitoring and repair, and establishing a super-emitter response program; (2) to encourage the deployment of innovative technologies and techniques for detecting and reducing methane emissions by providing additional options for the use of advanced monitoring; (3) to modify and refine certain elements of the proposed standards in response to concerns and information identified in an initial review of public comments on the November 2021 proposal; and (4) to provide additional information not included in the November 2021 proposal for public comment, such as the content for the new subparts that reflects the proposed standards and emission guidelines, and details of the timelines and other requirements that apply to states as they develop state plans to implement the emission guidelines.

In the November 2021 proposal, the EPA performed a comprehensive analysis of the available data from emission sources in the Crude Oil and Natural Gas source category and the latest available information on control measures and techniques to identify achievable, cost-effective measures to significantly reduce methane and VOC emissions, consistent with the requirements of section 111 of the CAA.

This supplemental proposal builds on that analysis to apply additional information and data provided to the Agency since the November 2021 proposal to identify areas to further strengthen standards, such as measures to address large emissions events, commonly referred to as super-emitters. If finalized and implemented, the proposed actions in this rulemaking, as detailed in the November 2021 proposal and this supplemental proposal, would lead to significant and cost-effective reductions in climate and health-harming pollution and encourage the continued development and deployment of innovative technologies to further reduce this pollution in the Crude Oil and Natural Gas source category.

42 U.S.C. 7411.

This supplemental proposal comprises distinct actions:

• Update, strengthen, and/or expand on the standards proposed in November 2021 under CAA section 111(b) for methane and VOC emissions from new, modified, and reconstructed facilities that commenced construction, reconstruction, or modification after November 15, 2021,

• Update, strengthen, and/or expand the presumptive standards proposed in November 2021 as part of the CAA section 111(d) emission guidelines for methane emissions from existing designated facilities that commenced construction, reconstruction, or modification on or before November 15, 2021,

• And establish the implementation requirements for states to limit methane pollution from existing designated facilities in the source category under CAA section 111(d).

The Oil and Natural Gas Industry is the United States' largest industrial emitter of methane, a highly potent GHG.

Methane and VOC emissions from the Crude Oil and Natural Gas source category result from a variety of industry operations across the supply chain. As natural gas moves through the necessarily interconnected system of exploration, production, storage, processing, and transmission that brings it from wellhead to commerce, emissions primarily result from intentional venting, unintentional gas carry-through (

e.g.,

vortexing from separator drain, improper liquid level settings, liquid level control valve on an upstream separator or scrubber not seating properly at the end of an automated liquid dumping event, inefficient separation of gas and liquid phases occurring upstream of tanks allowing some gas carry-through), routine maintenance, unintentional fugitive emissions, flaring, malfunctions, abnormal process conditions, and system upsets. These emissions are associated with a range of specific equipment and practices, including leaking valves, connectors, and other components at well sites and compressor stations; leaks and vented emissions from controlled storage vessels; releases from natural gas-driven pneumatic pumps and controllers; liquids unloading at well sites; and venting or under-performing flaring of associated gas from oil wells. Technical innovations have produced a range of technologies and best practices to monitor, eliminate or minimize these emissions, which in many cases have the benefit of simultaneously reducing multiple pollutants and recovering saleable product. These technologies and best practices have been deployed by individual oil and natural gas companies, required by state regulations, reflected in regulations issued by the EPA and other Federal agencies, or utilized by various non-industry groups and research teams.

Emissions from EPA (2022) Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2020. U.S. Environmental Protection Agency, EPA 430-R-22-003.

https://www.epa.gov/ghgemissions/draft-inventory-us-greenhouse-gas-emissionsand-sinks-1990-2020.

In developing this supplemental proposal, the EPA applied the latest available information to refine or supplement the analyses presented in the November 2021 proposal. This latest information provided additional insights into lessons learned from states' regulatory efforts, the emission reduction efforts of leading companies, the continued development of new and developing technologies, and peer-reviewed research from emission measurement campaigns across the United States (U.S.). As stated in the November 2021 proposal, the EPA solicited comment on all aspects of the proposed standards and stated its intent to issue a supplemental proposal that revisited and refined certain provisions of that proposal in response to information provided by the public. This supplemental proposal does just that. For instance, the EPA sought input in the November 2021 proposal on multiple aspects of the proposed approach for fugitive emissions monitoring at well sites, including the baseline emission threshold and other criteria (such as the presence of specific types of malfunction-prone equipment) that should be used to determine whether a well site is required to undertake ongoing fugitive emissions monitoring. (86 FR 63115; November 15, 2021). After considering the comments and information received, this supplemental proposal includes a revised approach for fugitive emissions monitoring at well sites utilizing modeling to establish the proposed monitoring frequency and detection method for individual sites based on the presence of specific types of equipment. In contrast to the November 2021 proposal, this supplemental proposal would establish an obligation for all well sites to routinely monitor for fugitive emissions and repair leaks found—ranging from a quarterly audio, visual, and olfactory (AVO) inspection for single wellhead-only sites to quarterly optical gas imaging (OGI) inspections for any site with significant production equipment. This revised approach to addressing fugitive emissions from well sites also would carry the monitoring requirements through the entire life of the well site and would specify the requirements for ceasing monitoring following well closures when production from the entire well site has stopped. The EPA is seeking comments about labor requirements to implement these monitoring requirements.

Super-emitter emissions events

were another key area in the November 2021 proposal for which the EPA solicited comment. (86 FR 63177; November 15, 2021). This supplemental proposal includes various standards that, when implemented by an owner or operator, could reduce or eliminate the occurrence of super-emitter emissions events, such as the inclusion of specific compliance assurance measures to ensure that flares are operating as designed with a continuously lit pilot. In addition, this supplemental notice proposes a super-emitter response program to trigger swift mitigation of super-emitter emissions events when they are identified through credible information provided by regulatory authorities or approved qualified third-party sources.

In the November 2021 proposal, the EPA solicited comment on the use of information collected by communities and others to address large emissions events, which this supplemental proposal now defines as “super-emitter emissions events.”

Content for the new subparts reflecting these proposed changes is available in the docket for this action (Docket ID No. EPA-HQ-OAR-2021-0317) and supplements the redline versions of NSPS OOOO and NSPS OOOOa provided in the November 2021 proposal (Docket ID Nos. EPA-HQ-OAR-2021-0317-0095 and EPA-HQ-OAR-2021-0317-0097). In addition, the EPA is providing an updated regulatory impact analysis (RIA) that seeks to account for the full impacts of these proposed actions.

Additionally, the EPA is seeking comment and information on the proposed provisions for the use of advanced methane measurement technologies for both periodic screening and continuous monitoring as an alternative to OGI. The revised proposal includes a matrix that provides various monitoring frequencies based on specific performance criteria a technology would need to meet in order to be used for periodic screening. In addition to this proposed matrix, this supplemental proposal includes provisions for requesting the use of alternative test method(s) that, where approved, could be used broadly for deploying these alternative technologies. Further, the EPA is proposing a framework for the use of continuous monitoring systems that provide a mass emissions rate with site-specific action levels based on changes in quarterly average emissions and on the detection of an acute large emission spike or event on a shorter term. Diverse stakeholders expressed strong interest in employing these new tools for methane identification and quantification, particularly for super-emitters, and in the EPA's creation of a regime to promote and accommodate their development and use. This proposal provides an approach for fostering those alternatives, which could provide a template for future innovation-conducive regulatory standards. The EPA is also seeking comment on the detection limits of all monitoring and inspection requirements.

Throughout this action, unless noted otherwise, the EPA is requesting comments on all aspects of the supplemental proposal to enable the EPA to develop a final rule that, consistent with our responsibilities under section 111 of the CAA, achieves the greatest possible reductions in methane and VOC emissions while remaining achievable, cost effective, and conducive to technological innovation. Because this preamble includes comment solicitations/requests on several topics and issues, we have prepared a separate memorandum that presents these comment requests by section and topic as a guide to assist commenters in preparing comments. This memorandum can be obtained from the Docket for this action (see Docket ID No. EPA-HQ-OAR-2021-0317). The title of the memorandum is “Standards of Performance for New, Reconstructed, and Modified Sources and Emissions Guidelines for Existing Sources: Oil and Natural Gas Sector Climate Review—Supplemental Proposed Rule Summary of Comment Solicitations.” It is not necessary to resubmit comments that were submitted for the November 2021 proposal.

B. Summary of the Major Provisions of the Regulatory Action

This supplemental proposal includes two distinct rulemaking actions under the CAA. First, the EPA is proposing specific changes to strengthen the proposed requirements under CAA section 111(b) for methane and VOC emissions from sources that commenced construction, modification, or reconstruction after November 15, 2021. These proposed revisions to strengthen the November 15, 2021, proposed standards of performance will be in a new subpart, NSPS OOOOb, and include proposed standards for emission sources previously not regulated for this source category.

Second, pursuant to CAA section 111(d), the EPA is proposing specific revisions to strengthen the first nationwide emission guideline (EG) for states to limit methane pollution from existing designated facilities in the Crude Oil and Natural Gas source category. The proposed revisions to strengthen the November 15, 2021, proposed presumptive standards will be in a new subpart, EG OOOOc. The emissions guidelines (EG) are designed to inform states in the development, submittal, and implementation of state plans that are required to establish standards of performance for GHGs (in the form of limitations on methane) from their designated facilities in the Crude Oil and Natural Gas source category.

As CAA section 111(a)(1) requires, the standards of performance under section 111(b) and presumptive standards under section 111(d) being proposed in this action reflect “the degree of emission limitation achievable through the application of the best system of emission reduction (BSER) which (taking into account the cost of achieving such reduction and any non-air quality health and environmental impact and energy requirement) the Administrator determines has been adequately demonstrated.”

In this proposed supplemental rulemaking, we evaluated new data made available to the EPA and information provided from public comments on the November 2021 proposal to update the analyses and evaluate whether revisions to the proposed BSER should be considered. For any potential control measure evaluated in this action, as in the November 2021 proposal, the EPA evaluated the emission reductions achievable through these measures and employed multiple approaches to evaluate the reasonableness of control costs associated with the options under consideration. For example, in evaluating controls for reducing VOC and methane emissions from new sources, we considered a control measure's cost-effectiveness under both a “single pollutant cost-effectiveness” approach and a “multipollutant cost-effectiveness” approach, to appropriately reflect that the systems of emission reduction evaluated in this rule typically achieve reductions in multiple pollutants simultaneously and secure a multiplicity of climate and public health benefits. We also

compared: (1) The capital costs that would be incurred through compliance with the proposed standards against the industry's current level of capital expenditures and (2) the annualized costs against the industry's estimated annual revenues. For a detailed discussion of the EPA's consideration of this and other BSER statutory elements, please see section III.E of this preamble, 86 FR 63133; November 15, 2021, and 86 FR 63153; November 15, 2021. Table 1 summarizes the applicability dates for the four subparts that the EPA's November 2021 proposal included.

The EPA notes that design, equipment, work practice or operational standards established under CAA section 111(h) (commonly referred to as “work practice standards”) reflect the “best technological system of continuous emission reduction” and that this phrasing differs from the “best system of emission reduction” phrase in the definition of “standard of performance” in CAA section 111(a)(1). Although the differences in these phrases may be meaningful in other contexts, for purposes of evaluating the sources and systems of emission reduction at issue in this rulemaking, the EPA has applied these concepts in an essentially comparable manner because the systems of emission reduction the EPA evaluated are all technological.

Table 1—Applicable Dates for Proposed Subparts Addressed in This Proposed Action

Subpart

Source type

Applicable dates

40 CFR part 60, subpart OOOO

New, modified, or reconstructed sources

After August 23, 2011, and on or before September 18, 2015.

40 CFR part 60, subpart OOOOa

New, modified, or reconstructed sources

After September 18, 2015, and on or before November 15, 2021.

40 CFR part 60, subpart OOOOb

New, modified, or reconstructed sources

After November 15, 2021.

40 CFR part 60, subpart OOOOc

Existing sources

On or before November 15, 2021.

The standards for dry seal centrifugal compressors will apply to those for which construction, reconstruction, or modification commenced after December 6, 2022.

The presumptive standards for dry seal centrifugal compressors will apply to those for which construction, reconstruction, or modification commenced on or before December 6, 2022.

1. Proposed Standards for New, Modified and Reconstructed Sources After November 15, 2021 (Proposed NSPS OOOOb)

As described in section IV of this preamble, the EPA is proposing several changes to the BSER and the standards for certain affected facilities based on a review of new data made available to the EPA and information provided in public comments. For the other standards proposed in the November 2021 proposal that generally remain unchanged in this action, we have provided further justifications or clarifications as needed based on the public comments and other additional information received, as described in section IV of this preamble. The proposed NSPS would apply to new, modified, and reconstructed emission sources across the Crude Oil and Natural Gas source category, including the production, processing, transmission, and storage segments, for which construction, reconstruction, or modification commenced after November 15, 2021, which is the date of publication of the proposed NSPS OOOOb. In addition, the EPA is proposing methane and VOC standards for one new emission source that is currently unregulated (

i.e.,

dry seal centrifugal compressors). Because standards for dry seal centrifugal compressors were not proposed in the November 2021 proposal, new, modified, and reconstructed dry seal centrifugal compressors are defined as those for which construction, reconstruction, or modification commenced after December 6, 2022.

In particular, this action proposes revisions to strengthen the proposed VOC and methane standards addressing fugitive emissions from well sites and pneumatic pumps; generally leaves unchanged the proposed sulfur dioxide (SO

) performance standard for sweetening units and the proposed VOC and methane performance standards for well completions, gas well liquids unloading operations, associated gas from oil wells, wet seal centrifugal compressors, reciprocating compressors, pneumatic controllers, storage vessels, fugitive emissions from compressor stations, and equipment leaks at natural gas processing plants; and proposes new VOC and methane standards for dry seal centrifugal compressors previously not regulated. A summary of the proposed BSER determination and proposed NSPS for new, modified, and reconstructed sources (NSPS OOOOb) is presented in Table 2. See section IV of this preamble for a complete discussion of the proposed changes to the BSER determination and proposed NSPS requirements.

This proposal also includes provisions for the use of alternative test methods using advanced methane detection technologies that allow for periodic screening or continuous monitoring for fugitive emissions and emissions from covers and closed vent systems (CVS) used to route emissions to control devices. These proposed alternatives would allow for advanced screening technologies, which could be used to identify large emissions or “super-emitter emissions events” sooner than the proposed use of periodic OGI monitoring for fugitive emissions, covers on storage vessels, and CVS. Various studies using aerial monitoring techniques have identified large emissions from these types of sources. Finally, in order to ensure that super-emitter emissions events are identified and mitigated as quickly as possible, the EPA is proposing a super-emitter response program where an owner or operator must investigate and take appropriate mitigation actions upon receiving certified notifications of detected emissions that are 100 kg/hr of methane or greater. See sections IV.A and IV.B of this preamble for a complete discussion of these proposed provisions.

2. Proposed EG for Sources Constructed Prior to November 15, 2021 (Proposed EG OOOOc)

As described in sections IV and V of this preamble, the EPA is proposing several changes to the BSER determinations and presumptive standards that were proposed under the authority of CAA section 111(d) in the November 2021 proposal. These changes are based on a review of new data made available to the EPA and information provided in public comments. In the November 2021 proposal the EPA proposed the first nationwide EG for GHG (in the form of methane limitations) for the Crude Oil and Natural Gas source category, including the production, processing, transmission, and storage segments (EG OOOOc).

This action proposes revisions to strengthen the proposed presumptive standards for methane addressing fugitive emissions from well sites, pneumatic controllers, pneumatic pumps, and wet seal centrifugal compressors; generally leaves unchanged the proposed methane presumptive standards for associated gas from oil wells, reciprocating compressors, storage vessels, fugitive emissions from compressor stations, and equipment leaks at natural gas processing plants; and proposes new methane presumptive standards for well liquids unloading operations and dry seal centrifugal compressors previously

not proposed to be regulated. A summary of the proposed BSER determination and proposed presumptive standards for EG OOOOc is presented in Table 3. See section IV of this preamble for a complete discussion of the proposed changes to the BSER determination and proposed presumptive standards.

This proposal also includes the same provisions described for NSPS OOOOb that allow for the use of alternative test methods using advanced methane detection technologies for periodic screening or continuous monitoring for fugitive emissions and emissions from covers and CVS used to route emissions to control devices. Finally, the EPA is also proposing a super-emitter response program, where an owner or operator that receives certified notifications of detected emissions that are 100 kg/hr or greater is obligated to take action to address those emissions. See sections IV.A and IV.B of this preamble for a complete discussion of these proposed provisions.

As stated in the November 2021 proposal,

when the EPA establishes NSPS for a source category, the EPA is required to issue EG to reduce emissions of certain pollutants from existing sources in that same source category. In such circumstances, under CAA section 111(d), the EPA must issue regulations to establish procedures under which states submit plans to establish, implement, and enforce standards of performance for existing sources for certain air pollutants to which a Federal NSPS would apply if such existing source were a new source. Thus, the issuance of CAA section 111(d) final EG does not impose binding requirements directly on sources but instead provides requirements for states in developing their plans. Although state plans bear the obligation to establish standards of performance, under CAA sections 111(a)(1) and 111(d), those standards of performance must reflect the degree of emission limitation achievable through the application of the BSER as determined by the Administrator. As provided in CAA section 111(d), a state may choose to take into account remaining useful life and other factors in applying a standard of performance to a particular source, consistent with the CAA, the EPA's implementing regulations, and the final EG.

See 86 FR 63117 (November 15, 2021).

In this supplemental proposal, the EPA is proposing changes to the BSER determinations and the degree of limitation achievable through application of the BSER for certain existing equipment, processes, and activities across the Crude Oil and Natural Gas source category. Those changes are discussed in section IV of this preamble. Section V of this preamble discusses the components of EG, including the steps, requirements, and considerations associated with the development, submittal, and implementation of state, tribal, and Federal plans, as appropriate. For the EG, the EPA is proposing to translate the degree of emission limitation achievable through application of the BSER (

i.e.,

level of stringency) into presumptive standards that states may use in the development of state plans for specific designated facilities. By doing this, the EPA has formatted the proposed EG such that if a state chooses to adopt these presumptive standards, once finalized, as the standards of performance in a state plan, the EPA could approve such a plan as meeting the requirements of CAA section 111(d) and the finalized EG, if the plan meets all other applicable requirements. In this way, the presumptive standards included in the EG serve a function similar to that of a model rule,

because they are intended to assist states in developing their plan submissions by providing states with a starting point for standards that are based on general industry parameters and assumptions. The EPA anticipates that providing these presumptive standards will create a streamlined approach for states in developing plans and the EPA in evaluating state plans. However, the EPA's action on each state plan submission is carried out via rulemaking, which includes public notice and comment. Inclusion of presumptive standards in the EG does not seek to pre-determine the outcomes of any future rulemaking.

The presumptive standards are not the same as a Federal plan under CAA section 111(d)(2). The EPA has an obligation to promulgate a Federal plan if a state fails to submit a satisfactory plan. In such circumstances, the final EG and presumptive standards would serve as a guide to the development of a Federal plan. See section VIII.F. for information on Federal plans.

Designated facilities located in Indian country would not be encompassed within a state's CAA section 111(d) plan. Instead, an eligible tribe that has one or more designated facilities located in its area of Indian country would have the opportunity, but not the obligation, to seek authority and submit a plan that establishes standards of performance for those facilities on its Tribal lands. If a tribe does not submit a plan, or if the EPA does not approve a tribe's plan, then the EPA has the authority to establish a Federal plan for that tribe. A summary of the proposed EG for existing sources (EG OOOOc) for the oil and natural gas sector is presented in Table 3. See sections IV and V of this preamble for a complete discussion of the proposed EG requirements.

Table 2—Summary of Proposed BSER and Proposed Standards of Performance for GHGs and VOCs

[NSPS OOOOb]

Affected source

Proposed BSER

Proposed standards of performance

for GHGs and VOCs

Super-Emitters

Root cause analysis and corrective action following notification of super-emitter emissions event

Root cause analysis and corrective action following notification of super-emitter emissions event.

Fugitive Emissions: Single Wellhead Only Well Sites and Small Well Sites

Quarterly AVO inspections

Quarterly AVO inspections. Repair for indications of potential leaks within 15 days of inspection.

Fugitive monitoring continues for all well sites until the site has been closed, including plugging the wells at the site and submitting a well closure report.

Fugitive Emissions: Multi-wellhead Only Well Sites (2 or more wellheads)

Quarterly AVO inspections

AND

Quarterly AVO inspections. Repair for indications of potential leaks within 15 days of inspection.

Monitoring and repair based on semiannual monitoring using OGI

Semiannual OGI monitoring (Optional semiannual EPA Method 21 monitoring with 500 ppm defined as a leak).

First attempt at repair within 30 days of finding fugitive emissions. Final repair within 30 days of first attempt.

Fugitive monitoring continues for all well sites until the site has been closed, including plugging the wells at the site and submitting a well closure report.

Fugitive Emissions: Well Sites with Major Production and Processing Equipment and Centralized Production Facilities

Bimonthly AVO monitoring (

i.e.,

every other month)

AND

Well sites with specified major production and processing equipment: Monitoring and repair based on quarterly monitoring using OGI

Bimonthly AVO inspections. Repair for indications of potential leaks within 15 days of inspection.

AND

Well sites with specified major production and processing equipment: Quarterly OGI monitoring. (Optional quarterly EPA Method 21 monitoring with 500 ppm defined as a leak).

First attempt at repair within 30 days of finding fugitive emissions. Final repair within 30 days of first attempt.

Fugitive monitoring continues for all well sites until the site has been closed, including plugging the wells at the site and submitting a well closure report.

Fugitive Emissions: Compressor Stations

Monthly AVO monitoring

AND

Monthly AVO monitoring.

AND

Monitoring and repair based on quarterly monitoring using OGI

Quarterly OGI monitoring. (Optional quarterly EPA Method 21 monitoring with 500 ppm defined as a leak).

First attempt at repair within 30 days of finding fugitive emissions. Final repair within 30 days of first attempt.

Fugitive Emissions: Well Sites and Compressor Stations on Alaska North Slope

Monitoring and repair based on annual monitoring using OGI

Annual OGI monitoring. (Optional annual EPA Method 21 monitoring with 500 ppm defined as a leak).

First attempt at repair within 30 days of finding fugitive emissions. Final repair within 30 days of first attempt.

Fugitive Emissions: Well Sites and Compressor Stations

(Optional) Screening, monitoring, and repair based on periodic screening using an advanced measurement technology instead of OGI monitoring

(Optional) Alternative periodic screening with advanced measurement technology instead of OGI and AVO monitoring according to minimum detection sensitivity of technology.

Fugitive Emissions: Well Sites and Compressor Stations

(Optional) Monitoring and repair based on using a continuous monitoring system instead of OGI monitoring

(Optional) Alternative continuous monitoring system instead of OGI and AVO monitoring.

Storage Vessels: A Single Storage Vessel or Tank Battery with PTE

of 6 tpy or more of VOC and PTE of 20 tpy or more of methane

Capture and route to a control device

95 percent reduction of VOC and methane.

Pneumatic Controllers: Natural gas-driven that Vent to the Atmosphere

Use of zero-emissions controllers

VOC and methane emission rate of zero.

Pneumatic Controllers: Alaska (at sites where onsite power is not available—continuous bleed natural gas-driven)

Use of low-bleed pneumatic controllers

Natural gas bleed rate no greater than 6 scfh.

Pneumatic Controllers: Alaska (at sites where onsite power is not available—intermittent natural gas-driven)

Monitor and repair through fugitive emissions program

OGI monitoring and repair of emissions from controller malfunctions.

Well Liquids Unloading

Employ techniques or technologies that eliminate methane and VOC emissions. If this is not feasible for safety or technical reasons, employ best management practices to minimize venting of emissions to the maximum extent possible

Perform liquids unloading with zero methane or VOC emissions. If this is not feasible for safety or technical reasons, employ best management practices to minimize venting of emissions to the maximum extent possible.

Wet Seal Centrifugal Compressors (except for those located at well sites)

Capture and route emissions from the wet seal fluid degassing system to a control device

95 percent reduction of methane and VOC emissions.

Dry Seal Centrifugal Compressors (except for those located at well sites)

Conduct preventative maintenance and repair to maintain flow rate at or below 3 scfm

Volumetric flow rate of 3 scfm.

Reciprocating Compressors (except for those located at well sites)

Repair or replace the reciprocating compressor rod packing in order to maintain a flow rate at or below 2 scfm

Volumetric flow rate of 2 scfm.

Pneumatic Pumps

Use of zero-emission pumps that are not powered by natural gas

Methane and VOC emission rate of zero.

Well Completions: Subcategory 1 (non-wildcat and non-delineation wells)

Combination of REC

and the use of a completion combustion device

Applies to each well completion operation with hydraulic fracturing.

REC in combination with a completion combustion device; venting in lieu of combustion where combustion would present demonstrable safety hazards.

Initial flowback stage: Route to a storage vessel or completion vessel (frac tank, lined pit, or other vessel) and separator.

Separation flowback stage: Route all salable gas from the separator to a flow line or collection system, re-inject the gas into the well or another well, use the gas as an onsite fuel source or use for another useful purpose that a purchased fuel or raw material would serve. If technically infeasible to route recovered gas as specified, recovered gas must be combusted. All liquids must be routed to a storage vessel or well completion vessel, collection system, or be re-injected into the well or another well.

The operator is required to have (and use) a separator onsite during the entire flowback period.

Well Completions: Subcategory 2 (exploratory, wildcat, and delineation wells and low-pressure wells)

Use of a completion combustion device

Applies to each well completion operation with hydraulic fracturing.

The operator is not required to have a separator onsite. Either: (1) Route all flowback to a completion combustion device with a continuous pilot flame; or (2) Route all flowback into one or more well completion vessels and commence operation of a separator unless it is technically infeasible for a separator to function. Any gas present in the flowback before the separator can function is not subject to control under this section. Capture and direct recovered gas to a completion combustion device with a continuous pilot flame.

For both options (1) and (2), combustion is not required in conditions that may result in a fire hazard or explosion, or where high heat emissions from a completion combustion device may negatively impact tundra, permafrost, or waterways.

Equipment Leaks at Natural Gas Processing Plants

LDAR

with bimonthly OGI

LDAR with OGI following procedures in appendix K.

Oil Wells with Associated Gas

Route associated gas to a sales line. If access to a sales line is not available, the gas can be used as an onsite fuel source, used for another useful purpose that a purchased fuel or raw material would serve, or routed to a flare or other control device that achieves at least 95 percent reduction in methane and VOC emissions

Route associated gas to a sales line. If access to a sales line is not available, the gas can be used as an onsite fuel source or used for another useful purpose that a purchased fuel or raw material would serve. If demonstrated that a sales line and beneficial uses are not technically feasible, the gas can be routed to a flare or other control device that achieves at least 95 percent reduction in methane and VOC emissions.

Sweetening Units

Achieve SO

emission reduction efficiency

Achieve required minimum SO

emission reduction efficiency.

tpy (tons per year).

OGI (optical gas imaging).

ppm (parts per million).

PTE (potential to emit).

scfh (standard cubic feet per hour).

BMP (best management practices).

scfm (standard cubic feet per minute).

REC (reduced emissions completion).

LDAR (leak detection and repair).

Table 3—Summary of Proposed BSER and Proposed Presumptive Standards for GHGs From Designated Facilities (EG OOOO

)

Designated facility

Proposed BSER

Proposed presumptive standards for GHGs

Super-Emitters

Root cause analysis and corrective action following notification of super-emitter emissions event

Root cause analysis and corrective action following notification by an EPA-approved entity or regulatory authority of a super-emitter emissions event.

Fugitive Emissions: Single Wellhead Only Well Sites and Small Well Sites

Quarterly AVO inspections

Quarterly AVO inspections. Repair for indications of potential leaks within 15 days of inspection.

Fugitive monitoring continues for all well sites until the site has been closed, including plugging the wells at the site and submitting a well closure report.

Fugitive Emissions: Multi-wellhead Only Well Sites (2 or more wellheads)

Quarterly AVO inspections

AND

Monitoring and repair based on semiannual monitoring using OGI

Quarterly AVO inspections. Repair for indications of potential leaks within 15 days of inspection.

Semiannual OGI monitoring (Optional semiannual EPA Method 21 monitoring with 500 ppm defined as a leak).

First attempt at repair within 30 days of finding fugitive emissions. Final repair within 30 days of first attempt.

Fugitive monitoring continues for all well sites until the site has been closed, including plugging the wells at the site and submitting a well closure report.

Fugitive Emissions: Well Sites and Centralized Production Facilities

Bimonthly AVO monitoring (

i.e.,

every other month)

AND

Well sites with specified major production and processing equipment: Monitoring and repair based on quarterly monitoring using OGI

Bimonthly AVO inspections. Repair for indications of potential leaks within 15 days of inspection.

AND

Well sites with specified major production and processing equipment: Quarterly OGI monitoring. (Optional quarterly EPA Method 21 monitoring with 500 ppm defined as a leak).

First attempt at repair within 30 days of finding fugitive emissions. Final repair within 30 days of first attempt.

Fugitive monitoring continues for all well sites until the site has been closed, including plugging the wells at the site and submitting a well closure report.

Fugitive Emissions: Compressor Stations

Monthly AVO monitoring

AND

Monitoring and repair based on quarterly monitoring using OGI

Monthly AVO monitoring.

AND

Quarterly OGI monitoring. (Optional quarterly EPA Method 21 monitoring with 500 ppm defined as a leak).

First attempt at repair within 30 days of finding fugitive emissions. Final repair within 30 days of first attempt.

Fugitive Emissions: Well Sites and Compressor Stations on Alaska North Slope

Monitoring and repair based on annual monitoring using OGI

Annual OGI monitoring. (Optional annual EPA Method 21 monitoring with 500 ppm defined as a leak).

First attempt at repair within 30 days of finding fugitive emissions. Final repair within 30 days of first attempt.

Fugitive Emissions: Well Sites and Compressor Stations

(Optional) Screening, monitoring, and repair based on periodic screening using an advanced measurement technology instead of OGI monitoring

(Optional) Alternative periodic screening with advanced measurement technology instead of OGI monitoring.

Fugitive Emissions: Well Sites and Compressor Stations

(Optional) Monitoring and repair based on using a continuous monitoring system instead of OGI monitoring

(Optional) Alternative continuous monitoring system instead of OGI monitoring.

Storage Vessels: Tank Battery with PTE of 20 tpy or More of Methane

Capture and route to a control device

95 percent reduction of methane.

Pneumatic Controllers: Natural gas-driven that Vent to the Atmosphere

Use of zero-emissions controllers

Methane emission rate of zero.

Pneumatic Controllers: Alaska (at sites where onsite power is not available—continuous bleed natural gas-driven)

Use of low-bleed pneumatic controllers

Natural gas bleed rate no greater than 6 scfh.

Pneumatic Controllers: Alaska (at sites where onsite power is not available—intermittent natural gas-driven)

Monitor and repair through fugitive emissions program

OGI monitoring and repair of emissions from controller malfunctions.

Gas Well Liquids Unloading

Employ techniques or technologies that eliminate methane emissions. If this is not feasible for safety or technical reasons, employ best management practices to minimize venting of emissions to the maximum extent possible

Perform liquids unloading with zero methane emissions. If this is not feasible for safety or technical reasons, employ best management practices to minimize venting of emissions to the maximum extent possible.

Wet Seal Centrifugal Compressors (except for those located at well sites)

Conduct preventative maintenance and repair to maintain flow rate at or below 3 scfm

Volumetric flow rate of 3 scfm.

Dry Seal Centrifugal Compressors (except for those located at well sites)

Conduct preventative maintenance and repair to maintain flow rate at or below 3 scfm

Volumetric flow rate of 3 scfm.

Reciprocating Compressors (except for those located at well sites)

Repair or replace the reciprocating compressor rod packing in order to maintain a flow rate at or below 2 scfm

Volumetric flow rate of 2 scfm.

Pneumatic Pumps

Use of zero-emission pumps that are not powered by natural gas

Methane emission rate of zero.

Equipment Leaks at Natural Gas Processing Plants

LDAR with bimonthly OGI

LDAR with OGI following procedures in appendix K.

Oil Wells with Associated Gas

C. Costs and Benefits

accordance with the requirements of Executive Order (E.O.) 12866, the EPA projected the emissions reductions, costs, and benefits that may result from this proposed action if finalized as proposed. These results are presented in detail in the RIA accompanying this proposal developed in response to E.O. 12866. The RIA focuses on the elements of the proposed rule that are likely to result in quantifiable cost or emissions changes compared to a baseline that incorporates changes to the regulatory requirements induced by the Congressional Review Act (CRA) resolution

but does not incorporate the proposed standards. We estimated the cost, emissions, and benefit impacts for the 2023 to 2035 period. We present the present value (PV) and equivalent annual value (EAV) of costs, benefits, and net benefits of this action in 2019 dollars.

As described in section IV.C, the EPA is proposing a super-emitter response program under the statutory rationale that super-emitters are a designated facility. The EPA is also proposing the program under a second rationale that the super-emitter response program constitutes work practice standards for certain sources and compliance assurance measures for other sources. Under either rationale, state plans are generally required to adopt the super-emitter response program either as presumptive standards or as measures that provide for the implementation and enforcement of such standards.

See November 2021 Proposal, 86 FR at 63116 (discussing the CRA Resolution and its effect on regulatory requirements).

The initial analysis year in the RIA is 2023 as we assume the proposed rule will be finalized early in 2023. The NSPS will take effect immediately and impact sources constructed after publication of the proposed rule. The EG will take longer to go into effect as states will need to develop implementation plans in response to the rule and have them approved by the EPA. We assume in the RIA that this process will take 3 years, and so EG impacts will begin in 2026. The final analysis year is 2035, which allows us to provide 10 years of projected impacts after the EG is assumed to take effect.

The cost analysis presented in the RIA reflects a nationwide engineering analysis of compliance cost and emissions reductions, of which there are two main components. The first component is a set of representative or model plants for each regulated facility, segment, and control option. The characteristics of the model plant include typical equipment, operating characteristics, and representative factors including baseline emissions and the costs, emissions reductions, and product recovery resulting from each control option. The second component is a set of projections of activity data for affected facilities, distinguished by vintage, year, and other necessary attributes (

e.g.,

oil versus natural gas wells). Impacts are calculated by setting parameters on how and when affected facilities are assumed to respond to a particular regulatory regime, multiplying activity data by model plant cost and emissions estimates, differencing from the baseline scenario, and then summing to the desired level of aggregation. In addition to emissions reductions, some control options result in natural gas recovery, which can then be combusted in production or sold. Where applicable, we present projected compliance costs with and without the projected revenues from product recovery.

The EPA expects climate and health benefits due to the emissions reductions projected under this proposed rule. The EPA estimated the climate benefits of

methane (CH

) emission reductions expected from this proposed rule using the social cost of methane (SC-CH

) estimates presented in the “Technical Support Document: Social Cost of Carbon, Methane, and Nitrous Oxide Interim Estimates under E.O. 13990” (IWG 2021) published in February 2021 by the Interagency Working Group on the Social Cost of Greenhouse Gases (IWG). As a member of the IWG involved in the development of the February 2021 TSD, the EPA agrees that these estimates continue to represent at this time the most appropriate estimate of the SC-CH

until revised estimates have been developed reflecting the latest, peer-reviewed science. However, as discussed in Section VII.E, the EPA also presents a sensitivity analysis of the monetized climate benefits using a set of SC-CH

estimates that incorporates recent research addressing recommendations of the National Academies of Sciences, Engineering, and Medicine (2017). The EPA notes that the benefits analysis is entirely distinct from the statutory BSER determinations proposed herein and is presented solely for the purposes of complying with E.O. 12866.

Under the proposed rule, the EPA expects that VOC emission reductions will improve air quality and are likely to improve health and welfare associated with exposure to ozone, particulate matter with a diameter of 2.5 micrometers or less (PM

2.5

), and hazardous air pollutants (HAP). Calculating ozone impacts from VOC emissions changes requires information about the spatial patterns in those emissions changes. In addition, the ozone health effects from the proposed rule will depend on the relative proximity of expected VOC and ozone changes to population. In this analysis, we have not characterized VOC emissions changes at a finer spatial resolution than the national total. In light of these uncertainties, we present an illustrative screening analysis in appendix C of the RIA based on modeled oil and natural gas VOC contributions to ozone concentrations as they occurred in 2017 and do not include the results of this analysis in the estimate of benefits and net benefits projected from this proposal.

The projected national-level emissions reductions over the 2023 to 2035 period anticipated under the proposed requirements are presented in Table 4. Table 5 presents the PV and EAV of the projected benefits, costs, and net benefits over the 2023 to 2035 period under the proposed requirements using discount rates of 3 and 7 percent. The estimates presented in Tables 4 and 5 reflect an updated analysis compared with the RIA that accompanied the November 2021 proposal. The updated analysis not only incorporates the new provisions put forth in the supplemental proposal (in addition to the elements of the November 2021 proposal that are unchanged), but also includes key updates to assumptions and methodologies that impact both the baseline and policy scenarios. As such, the estimates presented in the tables are not directly comparable to corresponding estimates presented in the November 2021 proposal. Additionally, we note that the estimated emission reductions in both proposals may not fully characterize the emissions reductions achieved by this rule because they might not fully account for the emissions resulting from super-emitter emissions events that would be prevented or quickly corrected as a result of this rule.

The EPA solicits comments on any relevant data, appropriate methodologies, or reliable estimates to help quantify the costs, emissions reductions, benefits, and potential distributional effects related to super-emitter events, the proposed emissions control requirements for associated gas from oil wells, and the proposed storage vessel control requirements at centralized production facilities and in the gathering and boosting segment.

Table 4—Projected Emissions Reductions Under the Proposed Rule, 2023-2035 Total

Pollutant

Emissions reductions

(2023-2035 total)

Methane (million short tons)

VOC (million short tons)

9.7

Hazardous Air Pollutant (million short tons)

0.39

Methane (million metric tons CO

Eq.)

810

To convert from short tons to metric tons, multiply the short tons by 0.907. Alternatively, to convert metric tons to short tons, multiply metric tons by 1.102.

Carbon dioxide equivalent (CO

Eq.) calculated using a global warming potential of 25.

Table 5—Benefits, Costs, Net Benefits, and Emissions Reductions of the Proposed Rule, 2023 Through 2035

[Dollar estimates in millions of 2019 dollars]

Present value

Equivalent annual value

Present value

Equivalent annual value

3 Percent Discount Rate

Climate Benefits

$48,000

$4,500

$48,000

$4,500

3 Percent Discount Rate

7 Percent Discount Rate

Net Compliance Costs

$14,000

$1,400

$12,000

$1,400

Compliance Costs

19,000

1,800

15,000

1,800

Product Recovery

4,600

440

3,300

390

Net Benefits

34,000

3,200

36,000

3,100

Non-Monetized Benefits

Climate and ozone health benefits from reducing 36 million short tons of methane from 2023 to 2035.

2.5

and ozone health benefits from reducing 9.7 million short tons of VOC from 2023 to 2035.

HAP benefits from reducing 390 thousand short tons of HAP from 2023 to 2035.

Emissions reductions from the super-emitter response program.

Visibility benefits.

Reduced vegetation effects.

Values rounded to two significant figures. Totals may not appear to add correctly due to rounding.

Climate benefits are based on reductions in methane emissions and are calculated using four different estimates of the SC-CH

(model average at 2.5 percent, 3 percent, and 5 percent discount rates; 95th percentile at 3 percent discount rate). For the presentational purposes of this table, we show the benefits associated with the average SC-CH

at a 3 percent discount rate, but the Agency does not have a single central SC-CH

point estimate. We emphasize the importance and value of considering the benefits calculated using all four SC-CH

estimates; the present value (and equivalent annual value) of the additional benefit estimates ranges from $19 billion to $130 billion ($2.1 billion to 12 billion) over 2023 to 2035 for the proposed option. Please see Table 3-5 and Table 3-8 of the RIA for the full range of SC-CH

estimates. As discussed in Section 3 of the RIA, a consideration of climate benefits calculated using discount rates below 3 percent, including 2 percent and lower, are also warranted when discounting intergenerational impacts. Appendix B of the RIA presents the results of a sensitivity analysis using a set of SC-CH

estimates that incorporates recent research addressing recommendations of the National Academies of Sciences, Engineering, and Medicine (2017). All net benefits are calculated using climate benefits discounted at 3 percent.

A screening-level analysis of ozone benefits from VOC reductions can be found in appendix C of the RIA, which is included in the docket.

II. General Information

A. Does this action apply to me?

Categories and entities potentially affected by this action include:

Table 6—Industrial Source Categories Affected by This Action

Category

NAICS code

Examples of regulated entities

Industry

211120

Crude Petroleum Extraction.

211130

Natural Gas Extraction.

221210

Natural Gas Distribution.

486110

Pipeline Distribution of Crude Oil.

486210

Pipeline Transportation of Natural Gas.

Federal Government

Not affected.

State/local/tribal government

Not affected.

North American Industry Classification System (NAICS).

This table is not intended to be exhaustive, but rather provides a guide for readers regarding entities likely to be affected by this action. Other types of entities not listed in the table could also be affected by this action. To determine whether your entity is affected by this action, you should carefully examine the applicability criteria found in the final rule. If you have questions regarding the applicability of this action to a particular entity, consult the person listed in the

FOR FURTHER INFORMATION CONTACT

section, your air permitting authority, or your EPA Regional representative listed in 40 CFR 60.4 (General Provisions).

B. How do I obtain a copy of this document, background information, and other related information?

In addition to being available in the docket, an electronic copy of the proposed action is available on the internet. Following signature by the Administrator, the EPA will post a copy of this proposed action at

https://www.epa.gov/controlling-air-pollution-oil-and-natural-gas-industry.

Following publication in the

Federal Register

, the EPA will post the

Federal Register

version of the supplemental proposal and key technical documents at this same website and at Docket ID No. EPA-HQ-OAR-2021-0317 located at

https://www.regulations.gov/.

III. Purpose of This Regulatory Action

A. What is the purpose of this supplemental proposal?

On November 15, 2021, the EPA published a proposed rulemaking that included proposed NSPS and EGs to mitigate climate-destabilizing pollution and to protect human health by reducing GHG and VOC emissions from the Oil and Natural Gas Industry, specifically the Crude Oil and Natural Gas source category. The November 2021 proposal included comprehensive analyses of the available data for methane and VOC emissions sources in the Crude Oil and Natural Gas source category and the latest available information on control measures and techniques to identify achievable, cost-effective measures to significantly reduce emissions, consistent with the requirements of section 111 of the CAA. The November 2021 proposal also solicited comment and information on specific topics.

New information was received and reviewed that was not considered in the November 2021 proposal. As a result, changes to some of the standards and other provisions proposed in November 2021 are being proposed in this supplemental notice.

Some of the new information was provided by commenters during the November 2021 proposal public comment period. Approximately 470,000 public comment letters were submitted on the November 2021 proposal representing a wide range of stakeholders and state and tribal governments. The EPA reviewed and considered the comments received, including the responses to the specific solicitations for information and input in the development of this supplemental proposal. Several of the commenters

representing diverse stakeholder perspectives expressed general support for the proposal and requested that the EPA further strengthen the proposed standards and make them more comprehensive. Other commenters highlighted implementation or cost concerns related to some of the elements proposed in the November 2021 proposal. Some commenters also provided data and information that the EPA was able to use to refine or revise several of the standards included in the November 2021 proposal.

This supplemental proposal only addresses specific comments that the EPA determined warranted changes to what was proposed. It does not address/summarize all of the comments submitted on the November 2021 proposal. The EPA will continue to evaluate all the previously submitted comments, as well as new comments submitted on this supplemental action, in the development of a final NSPS OOOOb and EG OOOOc. All relevant comments submitted on both proposals will be responded to at that time.

In summary, the purpose of this supplemental proposed rulemaking is to update, strengthen, and expand the standards proposed in the November 2021 proposal under CAA section 111(b) for methane and VOC emissions from new, modified, and reconstructed facilities, and the presumptive standards proposed under CAA section 111(d) for methane emissions from existing sources. In addition, this proposal: (1) Proposes to reduce emissions from the source category more comprehensively by adding proposed standards for certain sources that were not addressed in the November 2021 proposal, revising the proposed requirements for fugitive emissions monitoring and repair, and by establishing a super-emitter response program to target timely mitigation of super-emitter emissions events; (2) encourages the deployment of innovative technologies and techniques for detecting and reducing methane emissions by providing additional options for the use of advanced monitoring; (3) modifies and refines certain aspects of the proposed standards in response to concerns and information submitted in public comments; and (4) provides additional information not included in the November 2021 proposal for public comment, such as content for the new subparts that reflects the proposed standards and emission guidelines, and details of the timelines and other implementation requirements that apply to states to limit methane pollution from existing designated facilities in the source category under CAA section 111(d).

This supplemental notice also includes an updated RIA that accounts for the full impacts of these proposed actions. If finalized and implemented, the proposed actions in this rulemaking, as detailed in the November 2021 proposal and this supplemental proposal, would result in significant and cost-effective reductions in climate and health-harming pollution while encouraging the continued development and deployment of innovative technologies to further reduce this pollution in the Crude Oil and Natural Gas source category.

The summary and rationale for changes to the November 2021 proposed NSPS OOOOb and EG OOOOc standards are presented in section IV of this preamble. For each change, a high-level summary of the relevant points raised by commenters leading to the change is provided, followed by the EPA's rationale for the change. In addition to changes from the November 2021 proposal that are the result of public comments, the EPA has also included changes made as a result of additional EPA review and consideration of available information.

Section V of this preamble proposes specific requirements for the implementation of the proposed EG to provide states with information needed for purposes of EG state plan development. First, we discuss changes to the proposed requirements for establishing standards of performance in state plans. Second, we discuss changes to the proposed components of an approvable state plan submission. Third, we discuss the proposed timing for state plan submissions, and changes to the proposed timeline for designated facilities to come into final compliance with the state plan.

Section VI of this preamble includes requirements for using optical gas imaging in leak detection as appendix K to 40 CFR part 60 (appendix K). It provides an overview of the November 2021 proposal, significant changes made to the proposal and the basis for those changes, and a summary of the updated appendix K requirements.

Section VII of this supplemental proposal includes updates to the impacts of the November 2021 NSPS proposal based on changes discussed in sections IV and V of this preamble.

The EPA is requesting comments on all aspects of the supplemental proposal to enable the EPA to develop a final rule that, consistent with our responsibilities under section 111 of the CAA, achieves the greatest possible reductions in methane and VOC emissions while remaining achievable, cost effective, and conducive to technological innovation. Because this preamble includes comment solicitations/requests on several topics and issues, we have prepared a separate memorandum that presents these comment requests by section and topic as a guide to assist commenters in preparing comments. This memorandum and supporting materials can be obtained from the Docket for this action (see Docket ID No. EPA-HQ-OAR-2021-0317). The title of the memorandum is “Standards of Performance for New, Reconstructed, and Modified Sources and Emissions Guidelines for Existing Sources: Oil and Natural Gas Sector Climate Review—Supplemental Proposed Rule Summary of Comment Solicitations.”

B. What date defines a new, modified, or reconstructed source for purposes of the proposed NSPS OOOOb?

For the reasons explained below, NSPS OOOOb would apply to all emissions sources (“affected facilities”) identified in the proposed 40 CFR 60.5365b, except dry seal centrifugal compressors, that commenced construction, reconstruction, or modification after November 15, 2021. NSPS OOOOb would apply to dry seal centrifugal compressor affected facilities that commence construction, reconstruction, or modification after December 6, 2022.

Pursuant to CAA section 111(b), the EPA proposed new source performance standards (NSPS) for a wide range of emissions sources in the Crude Oil and Natural Gas source category (to be codified in 40 CFR part 60 subpart OOOOb) in a

Federal Register

notice published November 15, 2021. Some of the proposed standards resulted from the EPA's review of the current NSPS codified at 40 CFR part 60 subpart OOOOa (NSPS OOOOa), while others were proposed standards for additional emissions sources that are currently unregulated. The emissions sources for which the EPA proposed standards in the November 2021 proposal are as follows:

• Well completions

• Gas well liquids unloading operations

• Associated gas from oil wells

• Wet seal centrifugal compressors

• Reciprocating compressors

• Pneumatic controllers

• Pneumatic pumps

• Storage vessels

• Collection of fugitive emissions components at well sites, centralized production facilities, and compressor stations

• Equipment leaks at natural gas processing plants

• Sweetening units

These standards of performance would apply to “new sources.” CAA section 111(a)(2) defines a “new source” as “any stationary source, the construction or modification of which is commenced after the publication of regulations (or, if earlier, proposed regulations) prescribing a standard of performance under this section which will be applicable to such source.” Because the proposed regulation proposing the standards for these emission sources was published November 15, 2021, “new sources” to which these standards apply are those that commenced construction, reconstruction, or modification after November 15, 2021.

We received comments on the November 2021 proposal that it lacks regulatory text and therefore should not be used to define new sources for purposes of NSPS OOOOb.

The EPA disagrees for the following reasons. CAA section 307(d)(3) specifies the information that a proposed rule under the CAA must contain, such as a statement of basis, supporting data, and major legal and policy considerations; the list of required information does not include proposed regulatory text. Similarly, the Administrative Procedures Act (APA), which governs most Federal rulemaking, does not require publication of the proposed regulatory text in the

Federal Register

. Section 553(b)(3) of the APA provides that a notice of proposed rulemaking shall include “

either

the terms or substance of the proposed rule

a description of the subjects and issues involved.” (Emphasis added). Thus, the APA clearly provides flexibility to describe the “subjects and issues involved” as an alternative to inclusion of the “terms or substance” of the proposed rule. See also

Rybachek

EPA,

904 F.2d 1276, 1287 (9th Cir. 1990) (the EPA's “failure to propose in advance the actual wording” of a regulation does not make the regulation invalid where the “proposal . . . clearly describe[s] `the subjects and issues' ” involved). The EPA solicits comments on whether CAA section 111(a) provides the EPA discretion to define “new sources” based on the publication date of a supplemental proposal and, if so, whether there are any unique circumstances here that would warrant the exercise of such discretion in this rulemaking by the EPA.

See Document ID Nos. EPA-HQ-OAR-2021-0317-0424, EPA-HQ-OAR-2021-0317-0539, EPA-HQ-OAR-2021-0317-0579, EPA-HQ-OAR-2021-0317-0598, EPA-HQ-OAR-2021-0317-0599, EPA-HQ-OAR-2021-0317-0815, and EPA-HQ-OAR-2021-0317-0929.

In addition to the proposed standards, this supplemental proposal includes proposed standards for an additional emissions source, specifically dry seal centrifugal compressors. Because the EPA is proposing standards for dry seal centrifugal compressors for the first time in this supplemental proposal, “new sources” to which these standards apply are dry seal centrifugal compressors that commence construction, reconstruction, or modification after the date this supplemental proposal is published, which is December 6, 2022.

C. What date defines an existing source for purposes of the proposed EG OOOOc?

The November 2021 proposal also included proposed emissions guidelines for states to follow and develop plans to regulate existing sources in the Crude Oil and Natural Gas source category under EG OOOOc. Under CAA section 111, a source is either new,

i.e.,

construction, reconstruction, or modification commenced after a proposed NSPS is published in the

Federal Register

(CAA section 111(a)(1)), or existing,

i.e.,

any source other than a new source (CAA section 111(a)(6)). Accordingly, any source that is not subject to the proposed NSPS OOOOb as described is an existing source subject to EG OOOOc. As explained, new sources, with the exception of dry seal centrifugal compressors, are those that commenced construction, reconstruction, or modification after November 15, 2021; therefore, existing sources are those that commenced construction, reconstruction, or modification on or before November 15, 2021. Similarly, because new dry seal centrifugal compressors are those that commenced construction, reconstruction, or modification after December 6, 2022, existing dry seal centrifugal compressors are those that commenced construction, reconstruction, or modification on or before December 6, 2022.

D. How will the proposed EG OOOOc impact sources already subject to NSPS KKK, NSPS OOOO, or NSPS OOOOa?

Sources currently subject to 40 CFR part 60, subpart KKK (NSPS KKK), 40 CFR part 60 subpart OOOO (NSPS OOOO), or NSPS OOOOa would continue to comply with their respective standards until a state or Federal plan implementing EG OOOOc becomes effective. For most designated facilities, the EPA proposes to conclude that compliance with the implementing state or Federal plan that is consistent with the presumptive standards in EG OOOOc would constitute compliance with the older NSPS because the presumptive standards proposed for EG OOOOc result in the same or greater emission reductions than the current standards in the older NSPS.

In this rulemaking, the EPA is proposing standards for dry seal centrifugal compressor and intermittent bleed pneumatic controllers for the first time in NSPS OOOOb and EG OOOOc. Because these designated facilities (

i.e.,

dry seal centrifugal compressors and intermittent bleed pneumatic controllers) are not subject to regulation under a previous NSPS, they only need to comply with the state or Federal plan implementing EG OOOOc. The EPA is proposing presumptive standards for fugitive emissions at compressor stations, pneumatic pumps at natural gas processing plants, and pneumatic controllers at natural gas processing plants that are all the same or greater stringency than NSPS KKK, NSPS OOOO, and NSPS OOOOa, as applicable. Therefore, compliance with the state or Federal plan implementing EG OOOOc would satisfy compliance with the respective NSPS regulation. Additionally, the proposed presumptive standards in EG OOOOc for pneumatic pumps (excluding processing) and natural gas processing plant equipment leaks are more stringent than the standards in NSPS OOOOa for pneumatic pumps and all three NSPS for natural gas processing plant equipment leaks, and therefore compliance with the state or Federal plan implementing EG OOOOc would satisfy compliance with the respective NSPS regulation.

For wet seal centrifugal compressors, two different standards are in place for the older NSPS. NSPS KKK is an equipment standard that provides several compliance options including: (1) Operating the compressor with the barrier fluid at a pressure that is greater than the compressor stuffing box pressure; (2) equipping the compressor with a barrier fluid system degassing reservoir that is routed to a process or fuel gas system, or that is connected by a CVS to a control device that reduces VOC emissions by 95 percent or more; or (3) equipping the compressor with a system that purges the barrier fluid into a process stream with zero VOC emissions to the atmosphere. NSPS KKK exempts compressors from these requirements if it is either equipped with a closed vent system to capture and transport leakage from the compressor drive shaft back to a process or fuel gas system or to a control device

that reduces VOC emissions by 95 percent, or if it is designated for no detectable emissions. NSPS OOOO and NSPS OOOOa require 95 percent reduction of emissions from each centrifugal compressor wet seal fluid degassing system. NSPS OOOO and OOOOa also allow the alternative of routing the emissions to a process. The proposed presumptive standards under EG OOOOc would be a numerical emission limit of 3 scfm, as described in IV.G. of this preamble, and includes an alternative compliance option to reduce methane emissions by 95 percent by routing to a control or process. The proposed presumptive standard of 3 scfm is less stringent than the standards in NSPS OOOO and OOOOa, and therefore, compliance with a state or Federal plan implementing EG OOOOc using the 3 scfm presumptive standard would not satisfy compliance with NSPS OOOO and NSPS OOOOa for wet seal centrifugal compressor designated facilities. However, the EPA is not aware of any wet seal centrifugal compressors subject to NSPS OOOO or NSPS OOOOa and the EPA believes that centrifugal compressors installed since those rules went into effect (August 2011 and September 2015) are utilizing dry seals rather than wet seals. For wet seal centrifugal compressors currently subject to KKK (those designated as new sources between January 1984 and August 2011), compliance with NSPS KKK would allow for compliance with the state or Federal plan implementing EG OOOOc because the zero emissions limit would also achieve the 3 scfm limit proposed in EG OOOOc. For an owner or operator who uses the alternative compliance method proposed in EG OOOOc of routing to a control or process, achieving 95 percent emissions reductions can be accomplished using the same compressor requirements as required in NSPS OOOOa. Thus, compliance with a state or Federal plan implementing EG OOOOc using the 95 percent control alternative would satisfy compliance with NSPS OOOO and NSPS OOOOa for wet seal centrifugal compressor designated facilities.

The NSPS KKK standard is more stringent than the proposed 3 scfm presumptive standard in EG OOOOc for methane emissions. Accordingly, for centrifugal compressors, NSPS KKK would still apply to compressors at natural gas processing plants for which construction, reconstruction, or modification commenced after January 20, 1984, and on or before August 23, 2011.

There are two different standards for reciprocating compressors in the older NSPS: (1) NSPS KKK requires the use of a seal system and includes a barrier fluid system that prevents leakage of VOC to the atmosphere for reciprocating compressors located at natural gas processing plants, and (2) NSPS OOOO and NSPS OOOOa require changing out the rod packing every 3 years or routing emissions to a control. The proposed presumptive standard for EG OOOOc is a volumetric flow rate of 2 scfm. The proposed BSER is to repair and/or replace the reciprocating compressor rod packing in order to maintain the flow rate at or below 2 scfm (based on annual monitoring and additional preventative or corrective measures) and includes an alternative compliance option to route emissions to a process, as described in IV.I. of this preamble.

The NSPS KKK standard is more stringent than the proposed 2 scfm presumptive standard in EG OOOOc for methane emissions. Accordingly, for reciprocating compressors subject to NSPS KKK, the NSPS KKK provisions would still apply to reciprocating compressors at natural gas processing plants for which construction, reconstruction, or modification commenced after January 20, 1984, and on or before August 23, 2011. For NSPS KKK, several provisions effectively exempt certain reciprocating compressors at natural gas processing plants from the seal system requirements, including: an exemption for reciprocating compressors in wet gas service, a requirement that reciprocating compressors must be in VOC service (

i.e.,

at least 10 percent by weight VOC in the process fluid in contact with the compressor) for standards to apply, and an exemption for reciprocating compressors designated with no detectable emissions. If a reciprocating compressor at a natural gas processing plant was constructed, reconstructed, or modified between January 20, 1984, and August 23, 2011, is exempt from the provisions of NSPS KKK due to one of these conditions, it would be subject to the requirements of the state or Federal plan implementing EG OOOOc.

As explained in section XII.E.1.d. of the November 2021 proposal

and section IV.I of this preamble, the EPA finds that the proposed EG OOOOc standard is more efficient at discovering and reducing any emissions that may develop than the set 3-year replacement interval from NSPS OOOO and NSPS OOOOa. Overall, the proposed presumptive standards would produce more rod packing replacements, thereby reducing more emissions compared to the 3-year interval. Therefore, the EPA is proposing that compliance with the state or Federal plan implementing EG OOOOc will satisfy compliance with the respective NSPS OOOO and OOOOa regulations for reciprocating compressor designated facilities.

86 FR 63215 to 63220 (November 15, 2021).

The affected facility for storage vessels is defined in the NSPS OOOO and NSPS OOOOa as a single storage vessel with the potential to emit greater than 6 tons of VOC per year and the standard that applies is 95 percent emissions reduction. Under the proposed EG OOOOc, the designated facility is a tank battery with the potential to emit greater than 20 tons of methane per year with the same 95 percent emission reduction standard, as discussed in IV.J. of this preamble. Affected facilities under NSPS OOOO or OOOOa that are part of a designated facility under the EG would be required to meet the 95 percent reduction standard, and therefore would satisfy their respective NSPS requirement to do the same. Affected facilities under NSPS OOOO or OOOOa that emit 6 tpy or more of VOCs but that do not meet the potential to emit 20 tons of methane per year definition would continue to comply with the 95-percent emissions reduction standard in their respective NSPS. Scenarios regarding further physical or operational changes in NSPS OOOOb that would reclassify sources from the older NSPS and/or EG OOOOc into NSPS OOOOb are discussed in section IV.J.1.b. of this preamble.

Similarly, pneumatic controller affected facilities not located at natural gas processing plants are defined as single high-bleed controllers with a low-bleed standard under NSPS OOOO and NSPS OOOOa, while the designated facility under EG OOOOc is defined as a collection of natural gas-driven pneumatic controllers at a site with a zero emissions standard (discussed further in Section IV.D. of this preamble). The proposed zero-emissions presumptive standard in EG OOOOc is more stringent than the low-bleed standard found in the older NSPS, therefore the EPA is proposing that compliance with the state or Federal plan implementing EG OOOOc would satisfy compliance with the respective NSPS regulation for pneumatic controllers not located at a natural gas processing plant.

Lastly, standards for fugitive emissions from well sites under NSPS OOOOa require semiannual OGI monitoring on all components at the well site except for wellhead only well sites (which are not affected facilities), while the presumptive standards under the proposed EG OOOOc would require quarterly OGI monitoring at well sites

with major production and processing equipment, semiannual OGI combined with quarterly AVO inspections at multi-wellhead only well sites,

and quarterly AVO inspections for small sites and single wellhead well sites, as described in section IV.A of this preamble. It is clear that the proposed presumptive standards for well sites with major production and processing equipment and the proposed presumptive standards for multi-wellheads only well sites are both more stringent than the semiannual OGI monitoring standard under NSPS OOOOa because one would require more frequent OGI monitoring while the other would require AVO inspections in addition to semiannual OGI monitoring; therefore, for these existing wellsites that are also subject to NSPS OOOOa, compliance with proposed presumptive standards would be deemed in compliance with the semiannual OGI monitoring standard in NSPS OOOOa. With respect to existing single wellhead only well sites and small sites that are also subject to the semiannual monitoring under NSPS OOOOa, the EPA is proposing that compliance with the proposed presumptive standards, specifically quarterly AVO, would satisfy NSPS OOOOa for the following reasons. First, as explained in more detail in section IV.A, AVO is effective, and therefore OGI is unnecessary, for detecting fugitive emissions from many of the fugitive emissions components at these sites. Second, by requiring more frequent visits to the sites, the proposed presumptive standard would allow earlier detection and repair of fugitive emissions, in particular large emissions from components such as thief hatches on uncontrolled storage vessels. In light of the above, the EPA finds that the presumptive standards under the proposed EG OOOOc would effectively address the fugitive emissions at these well sites, and that semiannual OGI monitoring would no longer be necessary for these well sites that are also subject to NSPS OOOOa. For the reasons stated above, the EPA is proposing to conclude that compliance with the state or Federal plan implementing the presumptive fugitive emissions standards in the proposed EG OOOOc may be deemed to satisfy compliance with monitoring standards (

i.e.,

semiannual monitoring using OGI) in NSPS OOOOa for all well sites.

Because of a difference in the definition of a wellhead only well site in NSPS OOOOa and the proposed EG OOOOc, some single and multi-wellhead only well sites could be subject to the semiannual OGI monitoring under NSPS OOOOa.

The EPA is soliciting comment on all aspects of the proposed comparison of standards in the older NSPS to the proposed presumptive standards in EG OOOOc. Specifically, the EPA is requesting comment relevant to the comparison of stringency for compressors (both centrifugal and reciprocating) to NSPS KKK and for fugitive emissions monitoring at small well sites.

E. How does the EPA consider costs in this supplemental proposal?

In the November 2021 proposal, the EPA described the various approaches for evaluating control costs in its BSER analyses. 86 FR 63154-63157 (November 15, 2021). As described in that document, in considering the costs of the control options evaluated in this action, the EPA estimated the control costs under various approaches, including annual average cost-effectiveness and incremental cost-effectiveness of a given control. In its cost-effectiveness analyses, the EPA recognized and took into account that these multi-pollutant controls reduce both VOC and methane emissions in equal proportions, as reflected in the single-pollutant and multipollutant cost effectiveness approaches for the proposed NSPS OOOOb. The EPA also considered cost saving from the natural gas recovered instead of vented due to the proposed controls. In both the November 2021 proposal

and this supplemental proposal,

the EPA proposes to find that cost-effectiveness values up to $5,540/ton of VOC reduction are reasonable for controls that we have identified as BSER and within the range of what the EPA has historically considered to represent cost effective controls for the reduction of VOC emissions. Similarly, for methane, the EPA finds the cost-effectiveness values up to $1,970/ton of methane reduction to be reasonable for controls that we have identified as BSER in both the November 2021 proposal and this supplemental proposal, well below the $2,185/ton

of methane reduction that EPA has previously found to be reasonable for the industry.

86 FR 63155 (November 15, 2021).

See November 2021 TSD at Document ID No. EPA-HQ-OAR-2021-0317-0166 and Supplemental TSD for this action located at Docket ID No. EPA-HQ-OAR-2021-0317.

80 FR 56627 (June 6, 2016). See also, “Background Technical Support Document for the New Source Performance Standards 40 CFR part 60 subpart OOOOa (May 2016)”, at page 93, Table 6-7 located at Document ID No. EPA-HQ-OAR-2010-0505-7631.

For this supplemental proposal, we also updated the two additional analyses that the EPA performed for the November 2021 proposal to further inform our determination of whether the cost of control of the collection of proposed standards would be reasonable, similar to compliance cost analyses we have completed for other NSPS.

The two additional analyses include: (1) A comparison of the capital costs incurred by compliance with the proposed rules to the industry's estimated new annual capital expenditures, and (2) a comparison of the annualized costs that would be incurred by compliance with the proposed standards to the industry's estimated annual revenues. In this section, the EPA provides updated information regarding these cost analyses based on the proposed standards described in this notice. See 86 FR 63156 (November 15, 2021) for additional discussion on these two analyses.

For example, see our compliance cost analysis in “Regulatory Impact Analysis (RIA) for Residential Wood Heaters NSPS Revision. Final Report.” U.S. Environmental Protection Agency, Office of Air Quality Planning and Standards. EPA- 452/R-15-001, February 2015.

First, for the capital expenditures analysis, the EPA divided the nationwide capital expenditures projected to be spent to comply with the proposed standards by an estimate of the total sector-level new capital expenditures for a representative year to determine the percentage that the nationwide capital cost requirements under the proposal represent of the total capital expenditures by the sector. We combine the compliance-related capital costs under the proposed standards for the NSPS and for the presumptive standards in the proposed EG to analyze the potential aggregate impact of the proposal. The EAV of the projected compliance-related capital expenditures over the 2023 to 2035 period is projected to be about $1.4 billion in 2019 dollars. We obtained new capital expenditure data for relevant NAICS codes for 2019 from the U.S. Census 2020 Annual Capital Expenditures Survey.

While Census data on capital expenditures are available for 2020, these figures were heavily influenced by COVID-19-related impacts such that 2020 does is not an appropriate representative year to use in this analysis. According to these data, new capital expenditures for the sector in 2019 were about $156 billion in 2019

dollars.

Note that new capital expenditures for pipeline transportation of natural gas (NAICS 4862) includes only expenditures on structures as data on expenditures on equipment data are withheld to avoid disclosing data for individual enterprises. As a result, the capital expenditures used here represent an underestimate of the sector's expenditures. Comparing the EAV of the projected compliance-related capital expenditures under the proposal with the 2019 total sector-level new capital expenditures yields a percentage of about 0.9 percent, which is well below the percentage increase previously upheld by the courts.

U.S. Census Bureau, 2020 Annual Capital Expenditures Survey, Table 4b. Capital Expenditures for Structures and Equipment for Companies with Employees by Industry: 2019 Revised,

https://www.census.gov/data/tables/2020/econ/aces/2020-aces-summary.html,

accessed 7/12/2022.

The total capital expenditures for the same NAICS codes during COVID 19-impacted 2020 were about $90 billion.

Second, for the comparison of compliance costs to revenues, we use the EAV of the projected compliance costs without and with projected revenues from product recovery under the proposal for the 2023 to 2035 period then divided the nationwide annualized costs by the annual revenues for the appropriate NAICS code(s) for a representative year to determine the percentage that the nationwide annualized costs represent of annual revenues. Like we do for capital expenditures, we combine the costs projected to be expended to comply with the standards for NSPS and the presumptive standards in the proposed EG to analyze the potential aggregate impact of the proposal. The EAV of the associated increase in compliance cost over the 2023 to 2035 period is projected to be about $1.7 billion without revenues from product recovery and about $1.2 billion with revenues from product recovery (in 2019 dollars). Revenue data for relevant NAICS codes were obtained from the U.S. Census 2017 County Business Patterns and Economic Census, the most recent revenue figures available.

According to these data, 2017 receipts for the sector were about $358 billion in 2019 dollars. Comparing the EAV of the projected compliance costs under the proposal with the sector-level receipts figure yields a percentage of about 0.5 percent without revenues from product recovery and about 0.4 percent with revenues from product recovery. More data and analysis supporting the comparison of capital expenditures and annualized costs projected to be incurred under the rule and the sector-level capital expenditures and receipts is presented in the TSD for this action, which is in the public docket.

2017 County Business Patterns and Economic Census. The Number of Firms and Establishments, Employment, Annual Payroll, and Receipts by Industry and Enterprise Receipts Size: 2017,

https://www.census.gov/programs-surveys/susb/data/tables.2017.html,

accessed September 4. 2021. Note receipts data are available only for Economic Census years (years ending in 2 and 7) so 2017 data remains the most recent data available.

In considering the costs of the control options evaluated in this action, the EPA estimated the control costs under various approaches, including annual average cost-effectiveness and incremental cost-effectiveness of a given control. In its cost-effectiveness analyses, the EPA recognized and took into account that these multi-pollutant controls reduce both VOC and methane emissions in equal proportions, as reflected in the single-pollutant and multipollutant cost effectiveness approaches for the proposed NSPS OOOOb. The EPA also considered cost saving from the natural gas recovered instead of vented due to the proposed controls. Based on all of the considerations described, the EPA concludes that the costs of the controls that serve as the basis of the standards proposed in this action are reasonable. The EPA solicits comment on its approaches for considering control costs, as well as the resulting analyses and conclusions.

F. Legal Basis for Rulemaking Scope

In the November 2021 proposal, the EPA described the regulatory history of its authority to regulate methane emissions from the oil and gas source category under CAA section 111. The EPA explained that the 2016 Rule, 81 FR 35823 (June 3, 2016), established the agency's authority to regulate these methane emissions; the 2020 Policy Rule, 85 FR 57018 (September 14, 2020) had rescinded certain parts of the 2016 Rule, including its authorization to regulate methane; and a joint resolution under the Congressional Review Act (CRA), signed into law by President Biden on June 30, 2021, had rescinded the 2020 Policy Rule, and thereby reinstated the 2016 Rule's authorization to regulate methane. 86 FR 63135-36 (November 15, 2021).

In describing this history, the EPA noted that in the 2016 Rule, in response to comments, the EPA had explained that once it had listed a source category for regulation under section 111(b)(1)(A), it was not required to make, as a predicate to regulating GHG emissions from the source category, an additional pollutant-specific finding that those GHG emissions contribute significantly to dangerous air pollution (termed, a pollutant-specific significant contribution finding). However, in the alternative, the 2016 Rule did make such a finding, relying on information concerning the large amounts of methane emissions from the source category. 86 FR 63135 (November 15, 2021) (citing 81 FR 35843; June 3, 2016). The November 2021 proposal further noted that in the legislative history of the CRA resolution, Congress made clear its intent that section 111 did not require or authorize a pollutant-specific significant contribution finding, and the EPA confirmed that it agreed with that interpretation. 86 FR 63148 (November 15, 2021).

Some commenters on the November 2021 proposal reiterated the argument that the EPA is required to make a pollutant-specific significant contribution finding for GHG emissions from the oil and gas source category and stated that in order to make such a finding, the EPA must identify a standard or criteria for when a contribution is significant.

We may respond further to these comments in the final rule, but the November 2021 proposal notes that the legislative history of the CRA joint resolution rejected the position that a standard or criteria is necessary for determining significance, and explained, “It is fully appropriate for EPA to exercise its discretion to employ a facts-and-circumstances approach, particularly in light of the wide range of source categories and the air pollutants they emit that EPA must regulate under section 111.” 86 FR 63151 (November 15, 2021) (quoting House Report at 11). That continues to be the EPA's view and is consistent with decades of practice under section 111. The EPA has listed dozens of source categories, beginning in 1971,

in many cases on the basis of multiple pollutants emitted by the particular source category,

and has never identified a standard or criteria for determining significance.

Comments of Permian Basin Petroleum Ass'n, Document ID No. EPA-HQ-OAR-2021-0317-0793 at 3-4 (citing 85 FR 57018, 57038 (September 14, 2020).

List of Categories of Stationary Sources, 36 FR 5931 (March 31, 1971);

see

40 CFR part 60.

For example, when it listed “stationary gas turbines” as a source category, EPA considered emissions of particulates, nitrogen oxides, sulfur dioxide, carbon monoxide, and hydrocarbons. Addition to the List of Categories of Stationary Sources, 42 FR 53657 (October 3, 1977); Standards of Performance for New Stationary Sources: Proposed rule, 42 FR 53782, 53783 (October 3, 1977).

If the EPA were required to develop a standard or criteria to determine significance, any reasonable set of criteria would necessarily focus on the amount of emissions from the source category and the harmfulness of the pollutant emitted. In the case of the oil and gas source category, the “massive quantities of methane emissions”

contributed by the sector to the levels of well-mixed GHG in the atmosphere, as described in the November 2021 proposal, 86 FR 63148 (November 15, 2021), coupled with the potency of methane (with a global warming potential (GWP) of almost 30 or more than 80, depending on the time period of the impacts, 86 FR 63130; November 15, 2021), demonstrate that the source category's GHG emissions would be significant under any rational criteria-based approach. More specifically, as the EPA stated in the November 2021 proposal, as illustrated by the domestic and global GHGs comparison data summarized in that notice, the collective GHG emissions from the Crude Oil and Natural Gas source category are significant, whether the comparison is domestic (where this sector is the largest source of methane emissions, accounting for 28 percent of U.S. methane and 3 percent of total U.S. emissions of all GHGs), global (where this sector, accounting for 0.4 percent of all global GHG emissions, emits more than the total national emissions of over 160 countries, and combined emissions of over 60 countries), or when both the domestic and global GHG emissions comparisons are viewed in combination. See 86 FR 63131 (November 15, 2021).

The large quantity of methane emitted by the oil and gas source category is brought into sharp relief by the fact that, as the November 2021 proposal further stated, no single GHG source category dominates on the global scale. While the Crude Oil and Natural Gas source category, like many (if not all) individual GHG source categories, could appear small in comparison to total emissions, in fact, it is a very important contributor in terms of both absolute emissions, and in comparison, to other source categories globally or within the U.S. See 86 FR 63131 (November 15, 2021).

Importantly, the oil and gas source category is the largest emitter of methane of any source category in the United States. 86 FR 63129 (November 15, 2021). As described in the November 2021 proposal, methane is a potent greenhouse gas; over a 100-year timeframe, it is nearly 30 times more powerful at trapping climate warming heat than CO

, and over a 20-year timeframe, it is 83 times more powerful. Because methane is a powerful greenhouse gas and is emitted in large quantities, reductions in methane emissions provide a significant benefit in reducing near-term warming. Indeed, one third of the warming due to GHGs that we are experiencing today is due to human emissions of methane. See 86 FR 63129 (November 15, 2021).

The large amounts of methane emissions from the oil and gas source category in relation to other domestic and global sources of methane, coupled with the harmfulness of methane, should be considered more than sufficient to satisfy any criterion or standard for evaluating significant contribution. In particular, in the context of a problem like climate change that is caused by the collective contribution of many different sources, the fact that the oil and gas source category has the largest amount of methane emissions in the United States confirms that those emissions would meet a criterion or standard for significance.

The EPA acknowledges that the collective nature of the climate change problem means it will likely also be appropriate to regulate other source categories of methane emissions that are not necessarily as large as the oil and gas source category,

cf. EPA

EME Homer City,

572 U.S. 489, 514 (2014) (affirming framework to address “the collective and interwoven contributions of multiple upwind States” to ozone nonattainment), as indicated by the fact that EPA has long regulated landfill gas, which consists of methane in 50 percent part. “Emission Guidelines and Compliance Times for Municipal Solid Waste Landfills; Final Rule,” 81 FR 59276, 59281 (August 29, 2016). But this does not mean that it would be appropriate to regulate

all

other types of sources, even ones with few emissions. In the past, the EPA has declined to regulate air pollutants emitted from source categories in quantities too small to be worrisome and because regulation would have produced little environmental benefit.

See Nat'l Lime Ass'n.

EPA,

627 F.2d 416, 426 & n.27 (D.C. Cir. 1980) (small amounts of emissions of nitrogen oxides and carbon monoxide from lime kilns was a key factor in EPA decision not to promulgate new source performance standards for those pollutants; citing Standards of Performance for New Stationary Sources Lime Manufacturing Plants—Proposed Rule, 42 FR 22506, 22507 (May 3, 1977)).

G. Inflation Reduction Act

The Inflation Reduction Act (IRA) was signed into law on August 16, 2022. Section 60113 of the IRA amended the CAA by adding section 136, “Methane Emissions and Waste Reduction Incentive Program for Petroleum and Natural Gas Systems.” Under this new section of the CAA, subsection 136(c), “Waste Emission Charge,” requires the Administrator to “impose and collect a charge on methane emissions that exceed an applicable waste emissions threshold under subsection (f) from an owner or operator of an applicable facility that reports more than 25,000 metric tons of carbon dioxide equivalent of greenhouse gases emitted per year pursuant to subpart W of part 98 of title 40, Code of Federal Regulations (40 CFR part 98), regardless of the reporting threshold under that subpart.” An “applicable facility” is defined under CAA section 136(d) by reference to specific industry segments as defined in the Greenhouse Gas Reporting Program (GHGRP) petroleum and natural gas systems source category (40 CFR part 98, subpart W, also referred to as “GHGRP subpart W”). Pursuant to CAA section 136(g), the charge is to be imposed and collected beginning with respect to emissions reported for calendar year 2024 and for each year thereafter.

CAA section 136(f) identifies several circumstances under which the charges shall not be imposed on an owner or operator of an affected facility. In particular, CAA section 136(f)(6)(A) states that “charges shall not be imposed pursuant to subsection (c) on an applicable facility that is subject to and in compliance with methane emissions requirements pursuant to subsections (b) and (d) of section 111 upon a determination by the Administrator that:

(i) Methane emissions standards and plans pursuant to subsections (b) and (d) of section 111 have been approved and are in effect in all States with respect to the applicable facilities; and

(ii) compliance with the requirements described in clause (i) will result in equivalent or greater emissions reductions as would be achieved by the proposed rule of the Administrator entitled `Standards of Performance for New, Reconstructed, and Modified Sources and Emissions Guidelines for Existing Sources: Oil and Natural Gas Sector Climate Review' (86 FR 63110 (November 15, 2021)), if such rule had been finalized and implemented.”

Per section 136(c)(6)(B) “if the conditions in clause (i) or (ii) of subparagraph (A) cease to apply after the Administrator has made the determination in that subparagraph, the applicable facility will again be subject to the charge under subsection (c) beginning in the first calendar year in which the conditions in either clause (i) or (ii) of that subparagraph are no longer met.”

The EPA intends to take one or more separate actions in the future to implement the Methane Emissions and Waste Reduction Incentive Program, including revisions to certain requirements of GHGRP subpart W, and will provide an opportunity for public comment on the implementation of the Methane Emissions and Waste Reduction Incentive Program in those actions. Accordingly, the EPA considers the implementation of the Methane Emissions and Waste Reduction Incentive Program to be outside the scope of this supplemental proposed rule. However, the EPA is requesting comments on the criteria and approaches that the Administrator

should consider in making the CAA section 136(f)(6)(A)(ii) determination (“IRA equivalence determination”) because the EPA expects that the public and regulated industry will be interested in how the scope of the final oil and gas standards and emission guidelines may influence the applicability of the statutory exemption.

With respect to CAA section 136(f)(6)(A)(ii), the Administrator must determine that the methane emission standards in effect pursuant to CAA sections 111(b) and (d) “will result in equivalent or greater emissions reductions as would be achieved” by the EPA's November 2021 proposed rule. As a general matter, the EPA believes that the changes being proposed in today's action do not reduce expected methane emission reductions relative to the November 2021 proposal. Instead, the EPA anticipates that most, if not all, of the proposed changes contained in this supplemental proposal would likely lead to greater methane emissions reductions when fully implemented. For this reason, the Agency further anticipates that promulgation of Federal and state standards consistent with this supplemental proposal would result in methane emissions reductions at least as great as the November 2021 proposal. However, at this point, the EPA's analysis is purely qualitative. The EPA does not believe that it is appropriate to quantitatively compare the emission reductions from the November 2021 proposal and this supplemental proposal because, as is discussed in section 1.3 of the RIA, the analysis of this supplemental proposal includes key updates to assumptions and methodologies that impact both the baseline and policy scenarios. As such, the estimated impacts presented in the RIA of this supplemental proposal are not directly comparable to corresponding estimates presented in the RIA of the November 2021 proposal.

Moreover, the statutory language in CAA section 136(f)(6)(A)(ii) does not indicate how the EPA should conduct this equivalency evaluation and what factors should influence how the EPA conducts the comparison. Because of this ambiguity in the statutory language, the EPA is requesting comments on how to best conduct this evaluation and on factors and assumptions the EPA should consider in conducting such an evaluation.

First, the EPA seeks comments on temporal elements of the evaluation. The EPA believes that the appropriate temporal comparison should be based on when requirements are fully implemented by the sources (

i.e.,

if a state phases in installation of zero-emitting pneumatic controllers over more than one year, the comparison should be made at the point that the emission guidelines require full use of zero-emitting controllers). The EPA seeks comment on this approach versus an alternative such as making a multi-year comparison beginning with the effective date of the rule. In either case, as discussed below, such a determination could be made prospectively based either on the rule finalized by the EPA or when state plans have been approved. As discussed in section V.D. of the supplemental proposal, the EPA is proposing to require the submission of state plans under EG OOOOc within 18 months after publication of the final EG. In addition, the EPA is proposing to require that state plans impose a compliance timeline on designated facilities to require final compliance with the standards of performance as expeditiously as practicable, but no later than 36 months following the state plan submittal deadline.

Second, the EPA seeks comments on geographical elements of the evaluation. Per the statutory language in CAA section 136(f)(6)(A)(i), the EPA's evaluation is to be done with respect to all states. The EPA requests comments on whether we should consider making a national evaluation of equivalency or whether we should consider a state-by-state evaluation instead. Under a national evaluation, the EPA envisions conducting an assessment of the reductions achieved across all states and then evaluating those reductions collectively against the collective reductions anticipated from implementation of the November 2021 proposal. Under a state-by-state evaluation, the EPA envisions needing to analyze whether every state is achieving equivalent or greater reductions than that state would have achieved under the November 2021 proposal.

Third, the EPA requests comments on whether the EPA should make the evaluation and the IRA equivalency determination in advance of states having submitted fully approvable plans or instead make the evaluation and IRA equivalency determination at a later date once the standards of performance pursuant to CAA section 111(b) and 111(d) are fully promulgated (

e.g.,

the EPA has approved state plans and/or developed a Federal Plan). In particular, the EPA request comments on whether the EPA's analysis should compare the November 2021 EG proposal and final EG OOOOc by assuming designated facilities would be subject to their corresponding EG presumptive standards once state plans are implemented, or whether we should compare the November 2021 EG proposal to the actual state plans that are approved. As to the latter approach, the EPA seeks comments on how a state's invocation of RULOF to apply a less stringent standard to a designated facility might affect the equivalency evaluation and IRA equivalency determination. In establishing standards of performance for individual sources, CAA section 111(d) and the EPA's regulations provide that states may invoke RULOF for the application of less stringent standards provided they meet the certain requirements established in the EPA's regulations and the EG (see section V.B.3 below). As a result, it is possible that those state plans (individually or collectively) may not result in equivalent or greater emissions reductions as would be achieved by full implementation of the presumptive standards in the November 2021 proposal, unless the state plans require other sources to overperform to compensate for the less stringent RULOF standards or the EPA's geographical evaluation is national in scope and national emissions result in equivalent or greater emissions reductions, even taking into account RULOF. The EPA requests comments on whether and how to account for the potential application of RULOF in state plans in the IRA equivalency determination and whether it would be appropriate to conduct any evaluation without considering the application of RULOF.

The EPA notes that nothing in the new CAA section 136 supersedes the EPA's statutory obligations under CAA section 111. The Methane Emission and Waste Reduction Incentive Program does not supersede the EPA's statutory obligation, under CAA section 111, to regulate methane emissions from the Crude Oil and Natural Gas source category. The EPA first regulated GHG emissions from new, reconstructed, and modified sources through limitations on methane emissions in its 2016 NSPS OOOOa rulemaking. Therefore, the Agency is obligated to review those standards at least every 8 years pursuant to CAA section 111(b)(1)(B). Moreover, CAA section 111(d) requires the EPA to establish emission guidelines to regulate methane emissions from any existing sources in the sector to which a standard of performance would apply if it were a new source. Although CAA section 136(f)(6) provides that facilities may be exempted from the obligation to pay methane charges if they are

compliant with applicable CAA section 111(b) and (d) standards meeting certain criteria after the Administrator makes the IRA equivalency determination in CAA section 136(f)(6)(A), CAA section 136 does not provide that the Methane Emission and Waste Reduction Incentive Program may, in the alternative, serve as a compliance alternative for any applicable CAA section 111 standards for methane. Accordingly, affected facilities subject to the final NSPS OOOOb must continue to comply with the final standards of performance regardless of whether they are subject to or exempted from the waste emissions charge. Likewise, designated facilities subject to standards of performance pursuant to either an approved state plan or a federal plan according to the requirements in CAA section 111(d) and the final EG OOOOc must continue to comply with those standards regardless of whether they are subject to or exempted from the waste emissions charge. The EPA acknowledges the potential interplay between the provisions in this proposed rule and the Methane Emissions and Waste Reduction Incentive Program and invites comment on approaches for examining the economic impacts of these programs individually and collectively.

IV. Summary and Rationale for Changes to the Proposed NSPS OOOOb and EG OOOOc

A. Fugitive Emissions From Well Sites, Centralized Production Facilities, and Compressor Stations

As discussed in section XI.A of the November 2021 proposal preamble (86 FR 63169; November 15, 2021), fugitive emissions are unintended emissions that can occur from a range of components at any time. The magnitude of these emissions can also vary widely. The EPA has historically addressed fugitive emissions from the Crude Oil and Natural Gas source category through ground-based component level monitoring using OGI or Method 21 of appendix A-7 to 40 CFR part 60 (EPA Method 21).

This section presents a summary of the November 2021 proposal, the rationales for making certain changes to the proposed standards and requirements, and the resulting NSPS standards and EG presumptive standards the EPA is proposing via this supplemental proposal for fugitive emissions from well sites and compressor stations. For proposed standards and requirements that have not changed since the November 2021 proposal, their supporting rationales are not reiterated in this supplemental proposal. Rationale included in the November 2021 proposal for these standards and requirements can be found in that proposal preamble (86 FR 63110; November 15, 2021) and in the technical support document (TSD) for the November 2021 proposal located at (EPA-HQ-OAR-2017-0166).

1. Fugitive Emissions at Well Sites and Centralized Production Facilities

a. NSPS OOOOb

i. Summary of November 2021 Proposal

Affected Facility.

The November 2021 proposal defined the affected facility as the collection of fugitive emissions components located at well sites and centralized production facilities. The November 2021 proposal excluded “wellhead only well sites” as affected facilities under NSPS OOOOb, which were defined as well sites with one or more wellheads and no major production and processing equipment. Major production and processing equipment was defined as reciprocating or centrifugal compressors, glycol dehydrators, heater/treaters, separators, and storage vessels.

Definition of fugitive emissions component.

The November 2021 proposal included an expanded definition of fugitive emissions component that was intended to capture the known sources of large emission events. Specifically, the proposed definition in the November 2021 proposal defined a fugitive emissions component as “any component that has the potential to emit fugitive emissions of methane and VOC at a well site or compressor station, including valves, connectors, pressure relief devices, open-ended lines, flanges, all covers and CVS, all thief hatches or other openings on a controlled storage vessel, compressors, instruments, meters, natural gas-driven pneumatic controllers, or natural gas-driven pneumatic pumps. However, natural gas discharged from natural gas-driven pneumatic controllers or natural gas-driven pumps are not considered fugitive emissions if the device is operating properly and in accordance with manufacturers specifications. Control devices, including flares, with emissions resulting from the device operating in a manner that is not in full compliance with any Federal rule, state rule, or permit, are also considered fugitive emissions components.” (86 FR 63170; November 15, 2021).

Summary of November 2021 Proposal BSER Analysis.

The methodology used to determine BSER for the November 2021 proposal was presented in the section X.II.A of that proposal preamble (86 FR 63186; November 15, 2021). In the November 2021 proposal, the EPA proposed new work practice standards for the collection of fugitive emissions components located at well sites. The EPA proposed that well sites with total site-level baseline methane emissions less than 3 tpy would demonstrate, based on a one-time site-specific survey, that actual emissions are reflected in the baseline methane emissions calculation. For well sites with total site-level baseline methane emissions of 3 tpy or greater, the EPA proposed quarterly OGI or EPA Method 21 monitoring. The EPA also co-proposed an alternative set of work practice standards: for well sites with total site-level baseline methane emissions of 3 tpy or greater and less than 8 tpy semiannual OGI or EPA Method 21 monitoring would apply; and for well sites with total site-level baseline methane emissions of 8 tpy or greater, quarterly OGI or EPA Method 21 monitoring would apply. For sites using OGI to detect fugitive emissions under any of these proposed work practice standards, the EPA proposed that surveys would be conducted according to the procedures proposed as appendix K. See section VI of this preamble for more information regarding appendix K.

ii. Changes to Proposal and Rationale

The EPA is proposing certain changes to the November 2021 proposal standards for NSPS OOOOb. Specifically, the EPA is proposing: (1) To require OGI monitoring for well sites and centralized production facilities following the monitoring plan required in proposed 40 CFR 60.5397b instead of requiring the procedures being proposed in appendix K for these sites; (2) to expand the affected facility definition to include wellhead only well sites, which were previously exempt, and add a subcategory for small well sites; (3) to revise the definition of fugitive emissions component; (4) to require periodic AVO or other detection methods for all well sites and centralized production facilities (except those located on the Alaskan North Slope) at frequencies based on the subcategory of well site; (5) to require periodic OGI fugitive emissions monitoring based on the number and type of equipment located at the well site, in lieu of the baseline emissions calculations required in the November 2021 proposal; and (6) to include requirements for well closures that would indicate when fugitive emissions monitoring could stop.

Appendix K.

The EPA is not including a requirement to conduct OGI

monitoring according to the proposed appendix K for well sites or centralized production facilities, as was proposed in the November 2021 proposal. Instead, the EPA is proposing to require OGI surveys following the procedures specified in the proposed regulatory text for NSPS OOOOb (at 40 CFR 60.5397b) or according to EPA Method 21. The EPA received extensive comments

from oil and gas operators and other groups on the numerous complexities associated with following the proposed appendix K, especially considering the remoteness and size of many of these sites. In addition, commenters pointed out that OGI has always been the BSER for fugitive monitoring at well sites and was never designed as a replacement for EPA Method 21, while appendix K was designed for use at more complex processing facilities that have historically been subject to monitoring following EPA Method 21. The EPA agrees with the commenters and is proposing requirements within NSPS OOOOb at 40 CFR 60.5397b in lieu of the procedures in appendix K for fugitive emissions monitoring at well sites or centralized production facilities. See section VI of this preamble for additional information on what the EPA is proposing for appendix K related to other sources (

e.g.,

natural gas processing plants).

See Document ID Nos. EPA-HQ-OAR-2021-0317-0579, EPA-HQ-OAR-2021-0317-0743, EPA-HQ-OAR-2021-0317-0764, EPA-HQ-OAR-2021-0317-0777, EPA-HQ-OAR-2021-0317-0782, EPA-HQ-OAR-2021-0317-0786, EPA-HQ-OAR-2021-0317-0793, EPA-HQ-OAR-2021-0317-0802, EPA-HQ-OAR-2021-0317-0807, EPA-HQ-OAR-2021-0317-0808, EPA-HQ-OAR-2021-0317-0810, EPA-HQ-OAR-2021-0317-0814, EPA-HQ-OAR-2021-0317-0817, EPA-HQ-OAR-2021-0317-0820, EPA-HQ-OAR-2021-0317-0831, EPA-HQ-OAR-2021-0317-0834, and EPA-HQ-OAR-2021-0317-0938.

Affected facility and subcategorization of well sites.

The EPA is proposing to expand the affected facility definition to include the collection of fugitive emissions components at all well sites, including the previously excluded wellhead only well sites. Various studies, including a recent U.S. Department of Energy funded study on quantifying methane emissions from marginal wells,

demonstrate that fugitive emissions do occur from wellheads, and in some cases can be significant. As discussed in detail later in this section, the EPA evaluated emissions reductions resulting from the implementation of a fugitive emissions monitoring and repair program for a range of well site and centralized production facility configurations, ranging from the single wellhead only well site, to sites with specific major production and processing equipment present. While different types of monitoring techniques were found appropriate at the various site configurations evaluated, the EPA did not find support for an exemption of any site from the standards. Therefore, the EPA is proposing to define the affected facility as the collection of fugitive emissions components located at a well site or centralized production facility with no exemptions.

Bowers, Richard L.

Quantification of Methane Emissions from Marginal (Low Production Rate) Oil and Natural Gas Wells.

United States.

https://doi.org/10.2172/1865859.

Further, the EPA is proposing monitoring and repair programs specific to four distinct subcategories of well sites: (1) Single wellhead only well sites,

(2) wellhead only well sites with two or more wellheads, (3) well sites and centralized production facilities

with major production and processing equipment, and (4) small well sites. The third subcategory includes well sites and centralized production facilities that have: (1) One or more controlled storage vessels, (2) one or more control devices, (3) one or more natural gas-driven pneumatic controllers or pumps, or (4) two or more other major production and processing equipment. The fourth subcategory, small well sites, are single wellhead well sites that do not contain any controlled storage vessels, control devices, pneumatic controller affected facilities, or pneumatic pump affected facilities, and include only one other piece of major production and processing equipment. Major production and processing equipment that would be allowed at a small well site would include a single separator, glycol dehydrator, centrifugal and reciprocating compressor,

heater/treater, and storage vessel that is not controlled. By this definition, a small well site could only potentially contain a well affected facility (for well completion operations or gas well liquids unloading operations that do not utilize a CVS to route emissions to a control device) and a fugitive emissions components affected facility. No other affected facilities, including those utilizing CVS (such as pneumatic pumps routing to control) can be present for a well site to meet the definition of a small well site. The proposed monitoring requirements for each of these subcategories is described in more detail later in this section.

The EPA defines a wellhead only well site as a well site that contains one or more wellheads and no major production and processing equipment.

Centralized production facilities include one or more storage vessels and all equipment at a single surface site used to gather, for the purpose of sale or processing to sell, crude oil, condensate, produced water, or intermediate hydrocarbon liquid from one or more offsite natural gas or oil production wells. This equipment includes, but is not limited to, equipment used for storage, separation, treating, dehydration, artificial lift, combustion, compression, pumping, metering, monitoring, and flowline. Process vessels and process tanks are not considered storage vessels or storage tanks. A centralized production facility is located upstream of the natural gas processing plant or the crude oil pipeline breakout station and is a part of producing operations.

The EPA is proposing to exclude compressors that are located at well sites from the definition of a centrifugal affected facility and reciprocating affected facility, consistent with the November 2021 proposal. See 86 FR 63180 (November 15, 2021).

Definition of fugitive emissions component.

The EPA is proposing specific revisions to the definition of fugitive emissions component that was included in the November 2021 proposal. First, the EPA is proposing to add yard piping as one of the specifically enumerated components in the definition of a fugitive emissions component. While not common, pipes can experience cracks or holes, which can lead to fugitive emissions. The EPA is proposing to include yard piping in the definition of fugitive emissions component to ensure that when fugitive emissions are found from the pipe itself the necessary repairs are completed accordingly.

Second, the EPA is correcting an error made in the November 2021 proposal. The EPA had proposed that all thief hatches and other openings on all controlled storage vessels would be considered fugitive emissions components. This definition inadvertently included storage vessels that would already be subject to control as storage vessel affected facilities/designated facilities, including regular inspections of thief hatches and other sources of fugitive emissions that are separately required as part of the proposed standards for storage vessel affected facilities/designated facilities (see section IV.I of this preamble). The EPA is correcting that error in this supplemental proposal to avoid establishing redundant or duplicative requirements. Instead, the EPA is defining fugitive emissions components to include all thief hatches and other openings on storage vessels that are constructed, reconstructed, or modified after November 15, 2021, and not also subject to control as storage vessel affected facilities. This would include thief hatches and other openings on both uncontrolled storage vessels and storage vessels that are controlled for other purposes but not subject to NSPS OOOOb control requirements because fugitive emissions can occur from these components.

Third, the EPA is not defining control devices as fugitive emissions

components. One commenter stated that emissions resulting from noncompliance with control device requirements should not also be defined as fugitive emissions.

This commenter opined that since control devices are inherently designed to have emissions, even when well operated, it should be expected that some amount of methane and VOC would be detected during an OGI survey for fugitive emissions. The EPA agrees that control devices should not be treated as fugitive emissions components and is therefore revising the definition in this proposal to not include those devices. Further, as discussed in more detail in section IV.H of this preamble, the EPA anticipates that control devices are used to meet at least one of the emissions standards in the proposed rules, and as such, they would be subject to the control device requirements in NSPS OOOOb or EG OOOOc. See section IV.H of this preamble for additional discussion on proposed requirements specific to control devices.

See Document ID No. EPA-HQ-OAR-2021-0317-0808.

Finally, the EPA is not maintaining the inclusion of natural gas-driven pneumatic controllers or natural gas-driven pneumatic pumps as fugitive emissions components. These devices are both separate affected facilities with separate standards identified as BSER.

See sections IV.D and IV.E of this preamble for information about the proposed BSER for natural gas-driven pneumatic controllers and natural gas-driven pneumatic pumps, respectively.

As explained in sections IV.D for pneumatic controllers and IV.E for pneumatic pumps, only natural gas-driven pneumatic controllers and pumps are defined as affected facilities. For a controller or pump to not be an affected facility, it would need to be electric or solar, which would not have the potential to emit methane or VOC emissions. Therefore, the EPA does not consider pneumatic controllers or pneumatic pumps part of the fugitive emissions components when they are not affected facilities as controllers or pumps.

The EPA is proposing specific requirements throughout this supplemental proposal that will address emissions from controlled storage vessels and natural gas-driven pneumatic controllers and pumps, including requirements for quarterly OGI monitoring. These monitoring requirements provide compliance assurance that the proposed performance standards for these sources are being complied with and obviate any need to include these sources in the definition of a fugitive emissions component. For control devices, the EPA is proposing additional initial and continuous compliance measures to ensure the required emissions reductions are being achieved. See sections IV.D for discussion on pneumatic controllers, IV.E for discussion on pneumatic pumps, IV.H for discussion on combustion control devices, IV.J for discussion on storage vessels, and IV.K for discussion on covers and CVS.

The EPA notes quarterly OGI monitoring will also be performed to demonstrate compliance with specific standards for controlled storage vessels, natural gas-driven pneumatic controllers, natural gas-driven pneumatic pumps, and CVS associated with any affected facilities at well sites. This quarterly OGI monitoring would take place during the same quarterly OGI monitoring of the fugitive emissions components affected facility located at the same well site.

Comments received on monitoring requirements.

As discussed in the November 2021 proposal, the EPA proposed to require fugitive emissions monitoring using OGI based on the site-level methane baseline emissions, as determined, in part, through equipment and component count emissions factors. Further, the EPA solicited comment on adding routine AVO monitoring in addition to periodic OGI monitoring to help identify potential large emission events. Several comments, mostly from small businesses, were received regarding the use of AVO inspections because these are low cost and simple inspections that would identify indications of leaks, such as open thief hatches on storage vessels. These comments ranged from requiring monthly to annual AVO inspections in lieu of OGI monitoring, to requests to minimize the complexity of any associated recordkeeping and reporting requirements should the EPA require this type of inspection.

See Document ID Nos. EPA-HQ-OAR-2021-0317-0585, EPA-HQ-OAR-2021-0317-0814, EPA-HQ-OAR-2021-0317-0822, EPA-HQ-OAR-2021-0317-0929, and EPA-HQ-OAR-2021-0317-0935.

The EPA received substantive comments from several commenters on the November 2021 proposal regarding OGI monitoring arguing that the proposed requirements for well sites were unreasonable and would be difficult to implement, especially for well sites with total site-level baseline methane emissions less than 3 tpy. Specifically, these commenters

asserted that there would be challenges around calculating the site-level baseline emissions and that this task would be burdensome, while other commenters

asserted the calculations would result in no regular monitoring at sites that have leak-prone equipment. Further, commenters noted that it would be difficult to verify the emissions calculations, which could result in compliance and/or enforcement challenges. According to industry commenters,

the requirement to repeat the calculation when equipment is added or removed from the site would be especially burdensome. One of the commenters further stated this requirement would force owners and operators to constantly maintain an inventory of equipment, with some operators carrying this burden for hundreds to thousands of sites.

Moreover, the commenter indicated that the EPA has not explained the need for the proposed recalculation of site-level methane emissions based on equipment changes and how this would have an environmental benefit. Another commenter argued that the EPA did not properly explain the basis for the emissions thresholds and disagreed with the components and equipment included in the calculation, as well as the use of the GHGRP emissions factors.

See Document ID Nos. EPA-HQ-OAR-2021-0317-0808 and EPA-HQ-OAR-2021-0317-0814.

See Document ID No. EPA-HQ-OAR-2021-0317-0844.

See Document ID Nos. EPA-HQ-OAR-2021-0317-0808 and EPA-HQ-OAR-2021-0317-0814.

See Document ID No. EPA-HQ-OAR-2021-0317-0808.

See Document ID No. EPA-HQ-OAR-2021-0317-0814.

In response to the proposed site-specific survey to demonstrate that actual emissions are reflected in the baseline emissions calculation, some commenters asserted that well sites with emissions less than 3 tpy should not be exempt from regular monitoring. According to commenters, even small sites can have leaks with significant emissions.

For this reason, the commenters made the case that regular monitoring should be required for all sites. Some commenters also expressed that the requirement to calculate site-level methane baseline emissions and conduct an initial survey was confusing. As explained by one commenter, “[the] EPA states well sites with site-level baseline methane emissions [less than] 3 tpy are not required to conduct OGI monitoring.”

See 86 FR 63171 (November 15, 2021); however, since the EPA also proposed that well sites would be required to perform a survey to confirm that the actual emissions are less than 3 tpy, the commenter viewed this as a contradiction within the rule, thus making it unclear what the EPA was proposing.

See Document ID Nos. EPA-HQ-OAR-2021-0317-0568, EPA-HQ-OAR-2021-0317-0769, EPA-HQ-OAR-2021-0317-0844, and EPA-HQ-OAR-2021-0317-1267.

See Document ID No. EPA-HQ-OAR-2021-0317-0727.

One commenter indicated that monitoring should also be required for

wellhead only well sites because, even though less equipment (and so fewer components) is present at a wellhead only well site, the wellhead itself is a source of emissions, which should be inspected for fugitive emissions.

Other commenters provided similar comments and urged the EPA to remove the exemption for wellhead only well sites because these well sites have other smaller equipment that leaks and malfunctions,

with large emissions having been observed from these sites,

even though these sites do not have major production and processing equipment. Further, commenters noted that well sites with equipment with potentially significant emissions should not be considered a wellhead only well site or excluded from regular monitoring. The commenter urged the EPA that, if the wellhead only well site exemption is retained, it must only apply to single wellhead sites. Even if no associated equipment is located at a wellhead only well site, sites with multiple wellheads can have a number of components and subsequently potential sources of fugitive emissions.

This same commenter, who opposes the 3 tpy threshold, noted that “failure prone equipment” such as storage vessels, separators, flares, and natural gas-driven pneumatic controllers often operate incorrectly and can cause significant emissions.

This commenter argued that sites with this type of equipment should be required to monitor on a frequent basis.

See Document ID No. EPA-HQ-OAR-2021-0317-0769.

See Document ID No. EPA-HQ-OAR-2021-0317-0586.

See Document ID No. EPA-HQ-OAR-2021-0317-0844.

Id.

Another commenter noted that the one-time survey for sites less than 3 tpy does not address the problem of future leaks or malfunctions.

The commenter indicated that malfunctions account for a large amount of methane emissions and the commenter, therefore, recommended at least annual monitoring. Comments urging the EPA to exempt small, low producing wells were also received.

Specifically, one commenter argued that low producing wells are not disproportionately large emitters.

This commenter asked that the EPA exempt these wells, asserting that these sources can least afford monitoring and have relatively small emissions. The commenter further asked that the rule exempt wells defined by states as stripper wells.

See Document ID No. EPA-HQ-OAR-2021-0317-1267.

See Document ID Nos. EPA-HQ-OAR-2021-0317-0425 and EPA-HQ-OAR-2021-0317-0814.

See Document ID No. EPA-HQ-OAR-2021-0317-0425.

As illustrated by the comments, which specifically highlight many potential challenges related to implementation, compliance assurance, and efficacy in reducing emissions, the EPA agrees that the fugitive emissions monitoring program that was proposed in the November 2021 proposal should be clarified and improved in order to address the issues identified by the various commenters. As explained below, after considering the comments, additional data, and a revised analysis, the EPA is proposing revised fugitive emissions applicability criteria, monitoring frequencies, and detection methods at well sites and centralized production facilities.

Fugitive emissions monitoring and repair modeling.

In the November 2021 proposal, the EPA also solicited comment on other thresholds that could be used to set monitoring requirements for well sites, in lieu of using self-reported baseline emissions as a threshold. One of these options included an equipment-based approach, in which well sites with specific leak-prone equipment would have one set of requirements, while well sites with other equipment (or that lack leak-prone equipment) would have a different set of requirements. In comparison to a self-reported baseline emissions threshold, such an approach would ensure routine OGI monitoring takes place at sites that have equipment that is most likely to have fugitive emissions more frequently, while also being more straightforward for owners and operators to implement and for the EPA and state regulators to verify and enforce. The EPA received feedback and additional information in response to this solicitation and used that information to develop a new analysis based on this equipment-based concept.

To evaluate an equipment-based program, the EPA developed three distinct model plants. These model plants were designed to account for various equipment types located at sites and ranged from single wellhead only well sites to complex sites with various known sources of large emis

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