```

[Federal Register Volume 90, Number 9 (Wednesday, January 15, 2025)]
[Proposed Rules]
[Pages 3734-3752]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2024-31227]

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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 60

[EPA-HQ-OAR-2024-0358; FRL-12031-01-OAR]
RIN 2060-AW35

Reconsideration of 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: Proposed rule.

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SUMMARY: The Environmental Protection Agency (EPA) is proposing 
amendments to the New Source Performance Standards and Emission 
Guidelines for Existing Sources for the Crude Oil and Natural Gas 
Source Category in response to petitions for reconsideration. 
Specifically, this action proposes discrete technical changes to two 
different aspects of the rules. First, this action proposes discrete 
technical changes to the temporary flaring provisions for associated 
gas in certain situations. Second, this action proposes discrete 
technical changes to the vent gas net heating value (NHV) continuous 
monitoring requirements and alternative performance test (sampling 
demonstration) option for flares and enclosed combustion devices. In a 
letter dated May 6, 2024, the EPA notified petitioners and the public 
that the Agency granted reconsideration on these two aspects of the 
March 8, 2024 (89 FR 16820) final rule. These amendments neither 
propose changes to any other aspect of the final rule, nor propose to 
alter the substance of any emission standards within the final rule. 
Also, in this action, the EPA proposes to make formatting changes to 
the regulatory text to meet the required formatting standards of the 
Office of the Federal Register.

DATES: Comments. Comments must be received on or before March 3, 2025.
    Public Hearing. If anyone contacts us requesting a public hearing 
on or before January 20, 2025, we will hold a virtual public hearing. 
Please refer to the SUPPLEMENTARY INFORMATION for information on 
requesting and registering for a public hearing.

ADDRESSES: You may send comments, identified by Docket ID No. EPA-HQ-
OAR-2024-0358, by any of the following methods:
     Federal eRulemaking Portal: https://www.regulations.gov 
(our preferred method). Follow the online instructions for submitting 
comments.
     Email: [email protected]. Include Docket ID No. EPA-
HQ-OAR-2024-0358 in the subject line of the message.
     Mail: U.S. Environmental Protection Agency, EPA Docket 
Center, Docket ID No. EPA-HQ-OAR-2024-0358, Mail Code 28221T, 1200 
Pennsylvania Avenue NW, Washington, DC 20460.
     Hand/Courier Delivery: EPA Docket Center, WJC West 
Building, Room 3334, 1301 Constitution Avenue NW, Washington, DC 20004. 
The Docket Center's hours of operation are 8:30 a.m.-4:30 p.m., Monday-
Friday (except Federal Holidays).
    Instructions: All submissions received must include the Docket ID 
No. for this rulemaking. Comments received may be posted without change 
to https://www.regulations.gov, including any personal information 
provided. For detailed instructions on sending comments and additional 
information on the rulemaking process, see the SUPPLEMENTARY 
INFORMATION section of this document.

FOR FURTHER INFORMATION CONTACT: Frank Benjamin-Eze, Sector Policies 
and Programs Division (E143-05), Office of Air Quality Planning and 
Standards, U.S. Environmental Protection Agency, 109 T.W. Alexander 
Drive, P.O. Box 12055 RTP, North Carolina 27711; telephone number: 
(919) 541-3753; and email address: [email protected]. 
Additional questions may be directed to the following email address: 
[email protected].

SUPPLEMENTARY INFORMATION: 
    Participation in virtual public hearing. To request a virtual 
public hearing, contact the public hearing team at (888) 372-8699 or by 
email at [email protected]. If requested, the virtual public 
hearing will be held via virtual platform. The EPA will announce the 
date of the hearing and further details on the virtual public hearing 
at https://www.epa.gov/controlling-air-pollution-oil-and-natural-gas-operations. The hearing will convene at 11:00 a.m. Eastern Time (ET) 
and will conclude at 4:00 p.m. ET. The EPA may close a session 15 
minutes after the last pre-registered speaker has testified if there 
are not additional speakers.
    The EPA will begin pre-registering speakers for the hearing no 
later than 1 business day after a request has been received. To 
register to speak at the virtual hearing, please use the online 
registration form available at https://www.epa.gov/controlling-air-pollution-oil-and-natural-gas-operations or contact the public hearing 
team at (888) 372-8699 or by email at [email protected]. The 
last day to pre-register to speak at the hearing will be January 27, 
2025. Prior to the hearing, the EPA will post a general agenda that 
will list pre-registered speakers at: https://www.epa.gov/controlling-air-pollution-oil-and-natural-gas-operations.
    The EPA will make every effort to follow the schedule as closely as 
possible on the day of the hearing; however, please plan for the 
hearings to run either ahead of schedule or behind schedule. Each 
commenter will have 4 minutes to provide oral testimony. The EPA 
encourages commenters to submit a copy of their oral testimony as 
written comments to the rulemaking docket. The EPA may ask clarifying 
questions during the oral presentations but will not respond to the 
presentations at that time. Written statements and supporting 
information submitted during the comment period will be considered with 
the same weight as oral testimony and supporting information presented 
at the public hearing.
    Please note that any updates made to any aspect of the hearing will 
be posted online at https://www.epa.gov/controlling-air-pollution-oil-and-natural-gas-operations. While the EPA expects the hearing to go 
forward as set forth above, please monitor these websites or contact 
the public hearing team at (888) 372-8699 or by email at 
[email protected] to

[[Page 3735]]

determine if there are any updates. The EPA does not intend to publish 
a document in the Federal Register announcing updates.
    If you require the services of a translator or a special 
accommodation such as audio description, please pre-register for the 
hearing with the public hearing team and describe your needs by January 
22, 2025. The EPA may not be able to arrange accommodations without 
advance notice.
    Docket. The EPA has established a docket for this rulemaking under 
Docket ID No. EPA-HQ-OAR-2024-0358. All documents in the docket are 
listed in the Regulations.gov index. Although listed in the index, 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 as pdf 
versions that can only be accessed on the EPA computers in the docket 
office reading room. Certain data bases and physical items cannot be 
downloaded from the docket but may be requested by contacting the 
docket office at (202) 566-1744. The docket office has up to 10 
business days to respond to these requests. With the exception of such 
material, publicly available docket materials are available 
electronically in Regulations.gov.
    Written Comments. Submit your comments, identified by Docket ID No. 
EPA-HQ-OAR-2024-0358, at https://www.regulations.gov (our preferred 
method), or the other methods identified in the ADDRESSES section. Once 
submitted, comments cannot be edited or removed from the docket. The 
EPA may publish any comment received to its public docket. Do not 
submit to the EPA's docket at https://www.regulations.gov any 
information you consider to be CBI or other information whose 
disclosure is restricted by statute. This type of information should be 
submitted as discussed in the Submitting CBI section of this document.
    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). Please visit https://www.epa.gov/dockets/commenting-epa-dockets for additional submission methods; the full EPA 
public comment policy; information about CBI or multimedia submissions; 
and general guidance on making effective comments.
    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.
    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 Written Comments 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 
Office of Air Quality Planning and Standards (OAQPS) CBI Office at the 
email address [email protected], and as described above, should include 
clear CBI markings and note the docket ID. If assistance is needed with 
submitting large electronic files that exceed the file size limit for 
email attachments, and if you do not have your own file sharing 
service, please email [email protected] to request a file transfer 
link. If sending CBI information through the postal service, please 
send it to the following address: OAQPS Document Control Officer (C404-
02), OAQPS, U.S. Environmental Protection Agency, 109 T.W. Alexander 
Drive P.O. Box 12055 RTP, North Carolina 27711, Attention Docket ID No. 
EPA-HQ-OAR-2024-0358. The mailed CBI material should be double wrapped 
and clearly marked. Any CBI markings should not show through the outer 
envelope.
    Preamble acronyms and abbreviations. Throughout this document the 
use of ``we,'' ``us,'' or ``our'' is intended to refer to the EPA. We 
use multiple acronyms and terms in this preamble. While this list may 
not be exhaustive, to ease the reading of this preamble and for 
reference purposes, the EPA defines the following terms and acronyms 
here:

AGR Acid gas removal
AMP Alternative Monitoring Plan
API American Petroleum Institute
ASTM American Society for Testing and Materials
BPV back pressure valve
BSER best system of emission reduction
Btu/lb British thermal units per pound
Btu/scf British thermal units per standard cubic feet
[deg]C degrees Celsius
CAA Clean Air Act
CBI Confidential Business Information
CFR Code of Federal Regulations
CO2 carbon dioxide
CRA Congressional Review Act
CVS closed vent systems
EG emission guidelines
EJ environmental justice
EOR enhanced oil recovery
EPA Environmental Protection Agency
FR Federal Register
ft3 cubic feet
GC gas chromatograph
GHG greenhouse gas
GHGRP Greenhouse Gas Reporting Program
ICR information collection request
MACT maximum achievable control technology
MS mass spectrometer
NAICS North American Industry Classification System
NHV net heating value
NHVcz combustion zone NHV
NHVdil NHV dilution parameter
NHVS net heating values
NSPS new source performance standards
NTTAA National Technology Transfer and Advancement Act

[[Page 3736]]

O2 oxygen
OAQPS Office of Air Quality Planning and Standards
OMB Office of Management and Budget
PRA Paperwork Reduction Act
RFA Regulatory Flexibility Act
RIA regulatory impact analysis
RLSO redline strike out
scf standard cubic feet
TAR Tribal Authority Rule
UMRA Unfunded Mandates Reform Act
U.S. United States
VISR Video Imaging Spectro-Radiometry
VOC volatile organic compound(s)

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

I. General Information
    A. Does this action apply to me?
    B. Where can I get a copy of this document and other related 
information?
II. Statutory Background and Regulatory History
    A. Statutory Background of CAA Sections 111(b), 111(d), and 
General Implementing Regulations
    B. What is the regulatory history and background of NSPS and EG 
for the Crude Oil and Natural Gas Source Category?
III. Summary and Rationale of Proposed Amendments to NSPS OOOOb and 
EG OOOOc
    A. Temporary Flaring Provisions for Associated Gas in Certain 
Situations
    B. Vent Gas Net Heating Value (NHV) Continuous Monitoring 
Requirements and Alternative Performance Test (Sampling 
Demonstration) Option for Flares and Enclosed Combustion Devices
IV. How do these proposed amendments impact the implementation of EG 
OOOOc?
V. Summary of Cost, Environmental, and Economic Impacts
VI. Statutory and Executive Order Reviews
    A. Executive Order 12866: Regulatory Planning and Review and 
Executive Order 14094: Modernizing Regulatory Review
    B. Paperwork Reduction Act (PRA)
    C. Regulatory Flexibility Act (RFA)
    D. Unfunded Mandates Reform Act (UMRA)
    E. Executive Order 13132: Federalism
    F. Executive Order 13175: Consultation and Coordination With 
Indian Tribal Governments
    G. Executive Order 13045: Protection of Children From 
Environmental Health Risks and Safety Risks
    H. Executive Order 13211: Actions Concerning Regulations That 
Significantly Affect Energy Supply, Distribution, or Use
    I. National Technology Transfer and Advancement Act (NTTAA) and 
1 CFR Part 51
    J. Executive Order 12898: Federal Actions To Address 
Environmental Justice in Minority Populations and Low-Income 
Populations and Executive Order 14096: Revitalizing Our Nation's 
Commitment to Environmental Justice for All

I. General Information

A. Does this action apply to me?

    The source category that is the subject of this proposal is the 
Crude Oil and Natural Gas Source Category regulated under Clean Air Act 
(CAA) section 111, New Source Performance Standards (NSPS) and Emission 
Guidelines (EG). The 2022 North American Industry Classification System 
(NAICS) code for the source category is summarized in table 1. The 
NAICS codes serve as a guide for readers outlining the entities that 
this proposed action is likely to affect. The NSPS codified in 40 CFR 
part 60, subpart OOOOb, are directly applicable to affected facilities 
that begin construction, reconstruction, or modification after December 
6, 2022. As shown in table 1, Federal, State, and local government 
entities would not be affected by the NSPS action.

      Table 1--Industrial Source Categories Affected by NSPS Action
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                                                  Examples of regulated
             Category               NAICS code          entities
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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 and Local Government.......      . . . .  Not affected.
Tribal Government................       921150  American Indian and
                                                 Alaska Native Tribal
                                                 Governments.
------------------------------------------------------------------------

    This table is not intended to be exhaustive but rather provides a 
guide for readers regarding entities likely to be affected by the NSPS 
action. Other types of entities not listed in the table could also be 
affected by these NSPS action. To determine whether your entity is 
affected by any of the NSPS action, you should carefully examine the 
applicability criteria found in the final NSPS rule. If you have 
questions regarding the applicability of the NSPS rule to a particular 
entity, consult the person listed in the FOR FURTHER INFORMATION 
CONTACT section, your State air pollution control agency with delegated 
authority for NSPS, or your EPA Regional Office.
    The issuance of the CAA section 111(d) EG in March of 2024 did not 
impose binding requirements directly on existing sources. The EG 
codified in 40 CFR part 60, subpart OOOOc, applies to States in the 
development, submittal, and implementation of State plans to establish 
performance standards to reduce emissions of GHGs from designated 
facilities that are existing sources on or before December 6, 2022. 
Under the Tribal Authority Rule (TAR), eligible Tribes may seek 
approval to implement a plan under CAA section 111(d) in a manner 
similar to a State. See 40 CFR part 49, subpart A. Tribes may, but are 
not required to, seek approval for treatment in a manner similar to a 
State for purposes of developing a Tribal implementation plan (TIP) 
implementing the EG codified in 40 CFR part 60, subpart OOOOc. The TAR 
authorizes Tribes to develop and implement their own air quality 
programs, or portions thereof, under the CAA. However, it does not 
require Tribes to develop a CAA program. Tribes may implement programs 
that are most relevant to their air quality needs. If a Tribe does not 
seek and obtain the authority from the EPA to establish a TIP, the EPA 
has the authority to establish a Federal CAA section 111(d) plan for 
designated facilities that are located in areas of Indian country.\1\ A 
Federal plan would apply to all designated facilities located in the 
areas of Indian country covered by the Federal plan unless and until 
the EPA approves a TIP applicable to those facilities.
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    \1\ See the EPA's website, https://www.epa.gov/tribal/tribes-approved-treatment-state-tas, for information on those Tribes that 
have treatment as a state for specific environmental regulatory 
programs, administrative functions, and grant programs.

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[[Page 3737]]

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

    In addition to being available in the docket, at Docket ID No. EPA-
HQ-OAR-2024-0358 located at https://www.regulations.gov/, an electronic 
copy of this action is available on the internet at https://www.epa.gov/controlling-air-pollution-oil-and-natural-gas-operations. 
In accordance with 5 U.S.C. 553(b)(4), a brief summary of this proposed 
rule may be found at www.regulations.gov, Docket ID No. EPA-HQ-OAR-
2024-0358. Following publication in the Federal Register, the EPA will 
post the Federal Register version of the proposal and key technical 
documents at this same website.
    A memorandum showing the edits that would be necessary to 
incorporate the changes to 40 CFR part 60 subpart OOOOb and 40 CFR part 
60 subpart OOOOc proposed in this action is available in the docket 
(Docket ID No. EPA-HQ-OAR-2024-0358). Following signature by the EPA 
Administrator, the EPA also will post a copy of this document to 
https://www.epa.gov/controlling-air-pollution-oil-and-natural-gas-operations.

II. Statutory Background and Regulatory History

A. Statutory Background of CAA Sections 111(b), 111(d), and General 
Implementing Regulations

    The EPA's authority for this rulemaking is CAA section 111, 42 
U.S.C. 7411,which governs the establishment of standards of performance 
for stationary sources. This CAA section requires the EPA to list 
source categories to be regulated, establish standards of performance 
for air pollutants emitted by new sources in that source category, and 
establish EG for States to establish standards of performance for 
certain pollutants emitted by existing sources in that source category. 
For a comprehensive discussion of the statutory background of CAA 
sections 111(b), 111(d), and general implementing regulations, refer to 
the discussion provided in section IV.A (Statutory Background of the 
CAA sections 111(b), 111(d), and General Implementing Regulations) of 
the March 2024 final rule preamble. (89 FR 16846-16848; March 8, 2024).

B. What is the regulatory history and background of NSPS and EG for the 
Crude Oil and Natural Gas Source Category?

    On November 15, 2021, the EPA published a proposed rule (November 
2021 Proposal) to mitigate climate-destabilizing pollution and protect 
human health by reducing greenhouse gas (GHG) and volatile organic 
compound (VOC) emissions from the oil and natural gas industry,\2\ 
specifically the Crude Oil and Natural Gas source 
category.3 4 In the November 2021 Proposal, the EPA proposed 
new and updated standards of performance under section 111(b) of the 
CAA for GHGs (in the form of methane limitations) and VOC emissions 
from new, modified, and reconstructed sources in this source category, 
as well as revisions to standards of performance already codified at 40 
CFR part 60, subparts OOOO and OOOOa. The EPA also proposed EG under 
section 111(d) of the CAA for GHGs emissions (in the form of methane 
limitations) from existing sources (designated facilities).\5\ The EPA 
also proposed several related actions stemming from the joint 
resolution of Congress, adopted on June 30, 2021, under the 
Congressional Review Act (CRA), disapproving the EPA's final rule 
titled, ``Oil and Natural Gas Sector: Emission Standards for New, 
Reconstructed, and Modified Sources Review,'' September 14, 2020 (2020 
Policy Rule). Lastly, in the November 2021 Proposal the EPA proposed a 
protocol for optical gas imaging (OGI) under the part 60 general 
provisions. The only portions of the November 2021 Proposal that are 
relevant to this rulemaking are specific limited provisions of the NSPS 
(OOOOb) and EG (OOOOc) identified in this proposal.
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    \2\ The EPA characterizes the oil and natural gas industry 
operations as being generally composed of 4 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.
    \3\ ``Standards of Performance for New, Reconstructed, and 
Modified Sources and Emissions Guidelines for Existing Sources: Oil 
and Natural Gas Sector Climate Review.'' Proposed rule (86 FR 63110; 
November 15, 2021).
    \4\ 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.''
    \5\ The term ``designated facility'' means ``any existing 
facility which emits a designated pollutant and which would be 
subject to a standard of performance for that pollutant if the 
existing facility were an affected facility.'' See 40 CFR 60.21a(b).
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    On December 6, 2022, the EPA published a supplemental proposed rule 
(``December 2022 Supplemental Proposal'') that was composed of two main 
additions.\6\ First, the EPA proposed updated, strengthened, and 
expanded NSPS OOOOb standards compared to those proposed in November 
2021 under CAA section 111(b) for GHGs (in the form of methane 
limitations) and VOC emissions from new, modified, and reconstructed 
facilities. Second, the EPA proposed updated, strengthened, and 
expanded presumptive standards compared to those proposed for EG OOOOc 
in the November 2021 Proposal as part of the CAA section 111(d) EG for 
GHGs emissions (in the form of methane limitations) from designated 
facilities. For purposes of EG OOOOc, the EPA also proposed the 
implementation requirements for State plans developed to limit GHGs 
pollution (in the form of methane limitations) from designated 
facilities in the Crude Oil and Natural Gas source category under CAA 
section 111(d).
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    \6\ ``Standards of Performance for New, Reconstructed, and 
Modified Sources and Emissions Guidelines for Existing Sources: Oil 
and Natural Gas Sector Climate Review.'' Supplemental notice of 
proposed rulemaking (87 FR 74702; December 6, 2022).
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    On March 8, 2024, at 89 FR 16820 (hereafter, referred to as the 
March 2024 final rule), the EPA published the final rule with multiple 
separate actions to reduce air pollution emissions from the Crude Oil 
and Natural Gas source category. First, the EPA finalized NSPS OOOOb 
regulating GHG (in the form of a limitation on emissions of methane) 
and VOCs emissions for the Crude Oil and Natural Gas source category 
pursuant to CAA section 111(b)(1)(B). Second, the EPA finalized the EG 
in OOOOc to limit GHGs. Third, the EPA finalized several related 
actions (including final amendments to NSPS OOOOa) stemming from the 
joint resolution of Congress, adopted on June 30, 2021, under the CRA, 
disapproving the 2020 Policy Rule. Fourth, the EPA finalized a protocol 
under the General Provisions for optical gas imaging (OGI). The final 
rule became effective 60 days after publication, which was May 7, 2024.
    After the publication of the March 2024 final rule, the EPA 
identified, through its own internal reassessment of the regulatory 
text, as well as through communications with stakeholders and the 
Office of the Federal Register, erroneous cross-references and 
typographical errors within the regulatory text. Through those same 
processes, the EPA also identified the need for some minor wording 
changes to clarify erroneous language (or, in some cases, erroneous 
omissions) in the regulatory text, and to ensure that the

[[Page 3738]]

regulatory text aligns with the descriptions of the relevant provisions 
in the final rule preamble and other parts of the regulation(s). The 
EPA published an interim final rule (89 FR 62872; August 1, 2024) \7\ 
which made minor and non-substantive corrections to the March 2024 
final rule in order to correct the identified inadvertent errors.
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    \7\ Docket ID No. EPA-HQ-OAR-2021-0317-4057.
---------------------------------------------------------------------------

    Further, after the publication of the March 2024 final rule, the 
EPA received multiple petitions \8\ for reconsideration. On May 6, 
2024,\9\ we notified certain petitioners and the public that we granted 
reconsideration on two narrow and discrete aspects of the March 2024 
final rule: (1) The temporary flaring provisions for associated gas in 
certain situations; and (2) the vent gas NHV continuous monitoring 
requirements and alternative performance test (sampling demonstration) 
option for flares and enclosed combustion devices. These issues were 
raised in petitions for reconsideration from: (1) The American 
Petroleum Institute (API) and the American Exploration and Production 
Council (AXPC); \10\ (2) Second petition from API/AXPC; \11\ (3) The 
Texas Oil & Gas Association (TXOGA); \12\ (4) GPA Midstream Association 
(GPA Midstream); and (4) Environmental Integrity Project et. al.\13\ 
This action proposes amendments to the March 2024 final rule as a 
result of our reconsideration of these two narrow issues.\14\
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    \8\ See Docket No. EPA-HQ-OAR-2024-0358 for petitions for 
reconsideration received.
    \9\ See Docket No. EPA-HQ-OAR-2024-0358 for May 6, 2024, letter 
granting reconsideration.
    \10\ Letter to Michael S. Regan, EPA Administrator, from API and 
AXPC. Re: Provisions in the EPA's Final Rule ``New Source 
Performance Standards and Emission Guidelines for Crude Oil and 
Natural Gas Facilities: Climate Review.'' Reconsideration of the 
Final Rule. May 6, 2024. Hereinafter referred to as the ``May 2024 
API and AXPC petition.''
    \11\ Letter to Michael S. Regan, EPA Administrator, from TXOGA. 
Request for Reconsideration of the EPA's Final Rule ``New Source 
Performance Standards and Emission Guidelines for Crude Oil and 
Natural Gas Facilities: Climate Review.'' May 7, 2024. Hereinafter 
referred to as the ``May 2024 TXOGA petition.''
    \12\ Letter to Michael S. Regan, EPA Administrator; Gautam 
Srinivasan, Associate General Counsel, EPA; and Amy Hambrick, SPPD, 
EPA; from GPA Midstream Association. GPA Midstream Association 
Petition for Reconsideration and Request for Stay of Standards of 
Performance for New, Reconstructed, and Modified Sources and 
Emissions Guidelines for Existing Sources: Oil and Natural Gas 
Sector Climate Review. May 2, 2024. Hereinafter referred to as the 
``May 2024 GPA Midstream petition.''
    \13\ Letter to Michael S. Regan, EPA Administrator, from Air 
Alliance Houston; Clean Air Council; and Environmental Integrity 
Project. Re: Petition for Reconsideration of the Standards of 
Performance for New, Reconstructed, and Modified Sources and 
Emissions Guidelines for Existing Sources: Oil and Natural Gas 
Sector Climate Review; Final Rule, 89 FR 16,820 (March 8, 2024), 
Docket No. EPA-HQ-OAR-2021-0317. May 7, 2024. Hereinafter referred 
to as the ``May 2024 EIP, et al. petition.''
    \14\ In the May 6, 2024, letter to petitioners, the EPA also 
took the opportunity to clarify the applicable timeframe for 
performance testing with respect to NHV sampling.
---------------------------------------------------------------------------

III. Summary and Rationale of Proposed Amendments to NSPS OOOOb and EG 
OOOOc

    The amendments proposed in this action only relate to two narrow 
aspects of the March 2024 final rule: (1) The temporary flaring 
provisions for associated gas in certain situations; and (2) the vent 
gas NHV continuous monitoring requirements and alternative performance 
test (sampling demonstration) option for flares and enclosed combustion 
devices. This proposal does not address, and therefore the EPA is not 
reopening, any other aspects of the March 2024 final rule aside from 
these two specific aspects. Further, the two issues addressed in this 
proposal are separate and distinct from each other. Each of these two 
issues concern different portions of the March 2024 final rule that do 
not rely on the other. Also, in this action, the EPA proposes to make 
formatting changes to the regulatory text to meet the required 
formatting standards of the Office of the Federal Register.\15\
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    \15\ To view the proposed formatting changes, see the full 
redline strike out (RLSO) of the regulatory text located in the 
public docket at EPA-HQ-OAR-2024-0358.
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A. Temporary Flaring Provisions for Associated Gas in Certain 
Situations

    The final NSPS OOOOb requirements, and EG OOOOc presumptive 
standards (model rules), allow oil wells that are not routinely flaring 
associated gas (i.e., oil wells that route associated gas to sales line 
or equivalent alternative), to route associated gas to a flare or 
control device temporarily in certain situations. During situations 
where a malfunction or incident endangers the safety of operator 
personnel or the public, and during repair, maintenance including blow 
downs, a production test, or commissioning, owners and operators are 
allowed to route to a flare or control device for 24 hours or less per 
incident. Petitions for reconsideration include information that 
suggest that 24 hours for temporary flaring may not be sufficient time 
in these situations to troubleshoot and repair equipment. A summary of 
the relevant promulgated provisions being reconsidered is presented in 
section III.A.1, and specific concerns and supporting information 
provided by petitioners and other industry representatives are 
presented in section III.A.2 of this preamble. After consideration of 
the petitioners' concerns and supporting information, the EPA is 
proposing certain discrete changes to these particular requirements 
finalized in the March 2024 final rule. The proposed changes are 
presented in section III.A.3 of this preamble and the EPA's rationale 
for those proposed changes is presented in section III.A.4 of this 
preamble.
1. Summary of Promulgated Provisions Being Reconsidered
    When developing the March 2024 final rule requirements for 
associated gas, the EPA recognized that temporary situations may occur 
beyond the reasonable control of an owner or operator that could make 
it technically infeasible or unsafe to comply with the standard that 
requires the associated gas be recovered and either routed into a gas 
gathering flow line or collection system to a sales line, used as an 
onsite fuel source, used for another useful purpose that a purchased 
fuel or raw material would serve, or reinjected into the well or inject 
the recovered gas into another well. Therefore, for all associated gas 
wells subject to NSPS OOOOb and complying with one of these four 
options, the final rule allows owners and operators to route the 
associated gas to a flare or control device temporarily. 40 CFR 
60.5377b(d). The EG also includes similar provisions as part of the 
model rule at 40 CFR 60.5391c(c). The NSPS OOOOb final rule allow 
temporary flaring for the following situations:
    (1) During a malfunction or incident that endangers the safety of 
operator personnel or the public, an owner or operator is allowed to 
route to a flare or control device for 24 hours or less per incident.
    (2) During repair, maintenance including blow downs, a production 
test, or commissioning, an owner or operator is allowed to route to a 
flare or control device for 24 hours or less per incident.
    (3) During a temporary interruption in service from the gathering 
or pipeline system, an owner or operator is allowed to route to a flare 
or route to a control device for the duration of the temporary 
interruption not to exceed 30 days per incident.
    (4) During periods when the composition of the associated gas does 
not meet pipeline specifications for sources, or when the composition 
of the associated gas does not meet the quality requirements for use as 
a fuel for sources, or when the composition of the associated gas does 
not meet the quality requirements for another useful purpose, an owner 
or operator is

[[Page 3739]]

allowed to route to a flare or control device until the associated gas 
meets the required specifications or for 72 hours per incident, 
whichever is less.
    This proposed rule only concerns the first two situations listed 
above: (1) Malfunction/safety, and (2) repair/maintenance. The EPA is 
not reopening the other two situations listed. Specifically, the EPA is 
proposing changes to the following regulatory text only: 40 CFR 
60.5377b(d)(1) and (2), and 60.5391c(c)(1) and (2). To view the 
proposed changes, see the full redline strike out (RLSO) of the 
regulatory text located in the public docket at EPA-HQ-OAR-2024-0358.
2. Petitioner's Concerns and Supporting Information
    The EPA received a petition for reconsideration of the March 2024 
final rule from API-AXPC \16\ that included support for the EPA's 
general approach finalized at 40 CFR 60.5377b(d) that allows temporary 
flaring of associated gas for unique situations. However, petitioners 
highlighted that there are certain oil and natural gas production 
operations that are remote and spread out over many miles that are 
prone to severe winter weather events that could prevent operators from 
accessing these remote sites for longer than 24 hours. They provided, 
for example, that seasonal weather in North Dakota may cause local 
agencies to close roads whereby people and equipment would be prevented 
from arriving at a location within 24 hours. They requested that the 
EPA extend the temporary flaring provisions for malfunction and repair 
or maintenance activity to 72 hours from 24 hours as finalized. They 
added that the March 2024 final rule's specific timing restrictions for 
flaring were not in the proposals and therefore they did not have the 
opportunity to comment on the timelines finalized.
---------------------------------------------------------------------------

    \16\ April 2024 API and AXPC petition.
---------------------------------------------------------------------------

    The petitioners added that the March 2024 final rule preamble 
includes language that they believe indicates that the EPA intended to 
allow up to 72 hours for temporary flaring, ``. . .during repair, 
maintenance including blowdowns, a packer leakage test, a production 
test, or commissioning.'' \17\ Petitioners asking the EPA to reconsider 
this issue interpreted that it was the EPA's intention that 72 hours be 
allowed for temporary flaring, ``. . . during repair, maintenance 
including blowdowns, a packer leakage test, a production test, or 
commissioning,'' based on language in the final rule preamble.
---------------------------------------------------------------------------

    \17\ 89 FR 16820, at 16949.
---------------------------------------------------------------------------

    However, the EPA is now clarifying that the language cited by 
Petitioners was an inadvertent error. Elsewhere in the final rule 
preamble (e.g., Table 17--Situations and Durations where Associated Gas 
May Temporarily be Routed to a Flare or Control Device) and the final 
rule regulatory text correctly specify 24 hours as the allowance for 
temporary routing to a flare or control device during repair and 
maintenance. The final rule does allow for up to 72 hours in a 
different scenario, if associated gas does not meet pipeline 
specifications. In the March 2024 final rule, the EPA did not intend, 
and the existing regulatory text does not permit, to allow up to 72 
hours for repair and maintenance.
    As a follow-up to their petition, API conducted a survey \18\ from 
June through July 2024 with its members to understand the distribution 
of temporary associated gas flaring duration due to malfunction or 
maintenance and repair and submitted to the EPA for consideration. The 
API survey-provided responses include information on duration, data 
(month and year), and cause of temporary flaring events due to 
malfunction or maintenance or repair based on readily available data 
collected over 6 years (with 70 percent of the data collected within 
the last 3 years). The API survey data set represents over 2,800 total 
data points from six operators across three basins. The majority of the 
information (92 percent of the data points) was from the Permian Basin, 
with 6 percent and 2 percent from the Williston and San Juaquin Basins, 
respectively. Overall, according to API, the results indicate that over 
17 percent of events across the three basins required temporary flaring 
greater than 24 hours per event and over 15 percent of events required 
temporary flaring greater than 72 hours per event. Broken down by 
basin, 12 percent of the events in the Permian Basin required temporary 
flaring greater than 24 hours, and 11 percent required flaring 
durations greater than 72 hours. For the Williston Basin, 92 percent of 
events required flaring for greater than 24 hours and 78 percent 
required flaring for greater than 72 hours. For the San Joaquin Basin, 
7 percent of events required flaring greater than 24 hours and 0 
percent required flaring greater than 72 hours. The average duration of 
a temporary flaring event for all basins was reported to be 46 hours. 
The average flaring event durations by basin were 26 hours for the 
Permian Basin, 378 hours for the Williston Basin, and 8 hours for the 
San Joaquin Basin. API reported that inclement weather is one of many 
factors that contributes to the need for longer temporary flaring 
durations, which is reflected in the longer durations in the Williston 
Basin.\19\ They concluded that the data set supports their position 
that a 24-hour limit is a potential issue across various causes of 
temporary flaring including planned events, with geographically 
dispersed sites presenting additional challenges to rapid response.
---------------------------------------------------------------------------

    \18\ API (Prepared for API by John Beath Environmental, LLC). 
Operator Survey: Temporary Flaring. Slide Presentation and Excel 
Workbook. July 2024.
    \19\ The Williston Basin spans western North Dakota, 
northwestern South Dakota, eastern Montana and into a southern 
section of Canada.
---------------------------------------------------------------------------

    Additional takeaways from the survey data, according to API, are 
that: (1) Operators are already making efforts to reduce the duration 
of temporary flaring, with approximately 83 percent of flaring events 
represented in the data set being less than 24 hours; and (2) API 
believes that a 72-hour flaring limit would be more realistic, force 
operational innovation, minimize emissions, and would reduce the 
duration of roughly 15 percent of events. API acknowledged that 
although the results of the survey may not be statistically 
representative of the entire population (the entire industry in terms 
of all wells with associated gas), they believe that the collected data 
indicates that 72 hours is more appropriate than 24 hours as a national 
standard for temporary flaring due to malfunction or planned repair and 
maintenance.
    The EPA had also received a briefing by Hess Corporation prior to 
receiving the April 2024 API and AXPC petition on temporary flaring 
concerns.\20\ Their briefing stressed that well sites are unmanned 
facilities that are spread over hundreds of miles throughout North 
Dakota. They stressed that seasonal conditions such as road 
restrictions in spring and fall and extreme winter conditions can 
prevent personnel and equipment from getting to site, and that it may 
take days and up to over a week until access roads to a well site are 
cleared of snow. They added that, if a maintenance crew is required for 
repair, it can take multiple days even with equipment available. They 
suggested that it would be more appropriate and achievable for the EPA 
to allow 72

[[Page 3740]]

hours for temporary flaring due to safety and repair conditions.
---------------------------------------------------------------------------

    \20\ Hess Briefing for the EPA: Oil and Natural Gas Final 
Methane Rule NSPS OOOOb and EG OOOOc. February 29, 2024, Slide 
Presentation. See slides 19-23.
---------------------------------------------------------------------------

    Hess Corporation provided two specific scenarios in their briefing 
that they believe would require the need for flaring greater than 24 
hours: (1) Back pressure valve (BPV) failure; and (2) frozen sales gas 
piping on well site. Under the first scenario, they reported that it 
can take over a week to fix a BPV where an operator cannot fix it 
without involving others to perform corrective work and to obtain the 
necessary parts. Under the second scenario, once a freeze is 
identified, mitigation needs to be scheduled with a 3rd party and work 
can entail over a day to remove snow to provide access to thaw piping.
    In June of 2024, Hess Corporation presented an updated briefing 
\21\ to the EPA on their concerns related to the temporary flaring 
provisions which included additional supporting information for the 
above-mentioned scenarios. For example, for the first scenario above, 
Hess provided BPV failure notification to resolution timeline data 
indicating that it takes anywhere from a half day to 8 days (with an 
average resolution time of 3.2 days). Hess emphasized that weather-
related closures/restrictions that prevent personnel and repair 
equipment from getting to a site, and well sites in North Dakota that 
are unmanned facilities spread over hundreds of miles are both 
instances that would prevent maintenance and repair within 24 hours as 
required by the March 2024 final rule. Hess represented that their 
operations in North Dakota span an area of roughly 7,200 square miles. 
Thus, the company stated that even under normal business processes--
that incorporate efficiencies--maintenance and repair within 24 hours 
is unlikely and infeasible in many instances, even without a reason 
beyond an operator's control.
---------------------------------------------------------------------------

    \21\ Hess Briefing for the EPA: NSPS OOOOb Safety, Malfunction & 
Repair Temporary Flaring Allowance. June 3, 2024. Slide 
Presentation.
---------------------------------------------------------------------------

3. Summary of Proposed Changes
    After consideration of the petitioners' concerns and supporting 
information, the EPA is proposing to revise the temporary flaring 
provisions for associated gas in certain situations finalized in the 
March 2024 final rule. Specifically, these proposed revisions only 
apply to situations during: (1) Malfunction/safety, and (2) repair/
maintenance. The EPA is proposing to extend the allowable time for 
temporary flaring from 24 to 48 hours for malfunction, including for 
reasons of safety, and during all repairs and maintenance.
    Further, the EPA recognizes Petitioners' claim that there may be 
some instances in which an owner or operator encounters a malfunction, 
safety, repair, or maintenance event that requires routing to a flare 
or control device beyond 48 hours. To address such instances, the EPA 
is soliciting comment on allowing owners or operators of associated gas 
affected facilities to route to a flare or control device for up to 72 
hours if ``exigent circumstances'' exist. Such ``exigent 
circumstances'' would include situations where an owner or operator 
cannot physically access a site due to weather or other conditions 
(e.g., road closures). In addition to extreme weather events/road 
closures, the EPA is also soliciting comment on whether there are other 
specific ``exigent circumstances'' where the EPA should consider 
allowing an owner or operator to include as a basis of a ``exigent 
circumstance'' claim requiring the need to route to a flare or control 
device beyond the proposed 48-hour allowance for repairs and 
malfunctions. The EPA also solicits comment on the records and reports 
that should be required if the EPA were to include an allowance for 
owners or operators of associated gas affected facilities to route to a 
flare or control device for up to 72 hours for ``exigent 
circumstances.'' Specifically, the EPA solicits comment on requiring an 
owner or operator who must make use of the extended timeframe to 
maintain records that include: (1) A written description of the 
``exigent circumstance''; (2) the rationale for the need to route to a 
flare or control device beyond 48 hours; (3) a description of the 
measures taken to minimize temporary flaring/routing to a control 
device; and (4) the duration of temporary flaring/routing to a control 
device due to the identified ``exigent circumstance.'' Lastly, the EPA 
solicits comment on requiring an owner or operator to include a summary 
of their annual ``exigent circumstance'' recorded events in their 
annual report.
    The basis for the EPA's proposed changes and solicitations is 
discussed in III.A.4 of this preamble.
4. Basis for Proposed Changes
    The March 2024 final rule allows temporarily routing associated gas 
to a flare or control device for 24 hours during situations where a 
malfunction or incident endangers the safety of operator personnel or 
the public, and during repair, maintenance including blow downs, a 
production test, or commissioning. These provisions were based on 
requirements of existing State rules, information from the World Bank 
Global Flaring and Methane Reduction Partnership, and specific 
recommendations provided by comments received on the proposal and 
supplemental proposal.\22\
---------------------------------------------------------------------------

    \22\ 89 FR 16943 to 16944 and 89 FR 16948 to 16950.
---------------------------------------------------------------------------

    As discussed in section III.A.2 of this preamble, industry 
petitioners indicated that the 24-hour limitation for temporary routing 
to a flare or control device in the final rule during situations where 
a malfunction or incident endangers the safety of operator personnel or 
the public, and during repair, maintenance including blow downs, a 
production test, or commissioning, is not sufficient. They claim that a 
72-hour timeframe for all these situations is more appropriate for 
temporary routing to a flare or control device due to the unique 
characteristics of some well sites, weather conditions, or a 
combination of both.
    The EPA considered this information, and examined the scenarios 
provided by the petitioners where they claimed there was a need for 
temporary routing to a flare or control device beyond 24 hours. First, 
the information provided by petitioners is persuasive in demonstrating 
that a blanket 24-hour limit on temporary flaring can pose compliance 
challenges for certain owners and operators. While we still expect that 
owners and operators can feasibly limit temporary flaring to less than 
24 hours in a large majority of situations (and this is supported by 
the API survey data cited above), we acknowledge that in certain 
instances, fundamental aspects of well site operational schedules can 
make this requirement challenging, particularly for remote unmanned 
sites. The EPA understands that owners' and operators' operational 
schedules outline the staffing and work shifts of oil and gas 
operations, ensuring that personnel are available to monitor and 
respond to issues within a designated timeframe while maintaining safe 
and efficient operations. We recognize that challenges arise when 
problems occur outside of an operator's working hours, such as during 
night shifts, shift changes or when fewer staffs are present leading to 
delays in identifying and addressing repairs and malfunctions. Hess has 
shared information with the EPA highlighting how the 24 hour 
operational schedule may not be sufficient for quick response in such 
cases, particularly with the remote

[[Page 3741]]

nature of these sites.\23\ We also recognize that the gathering of 
available parts and prioritization of corrective work to correct a 
situation, such as the BPV failure example cited by Hess, could require 
the need for routing to a flare or control device for a period greater 
than 24 hours. Further, we also recognize that circumstances outside of 
the control of the owner/operator, such as weather events, can also 
impact the ability to address the situation within 24 hours.
---------------------------------------------------------------------------

    \23\ An example of the timeline challenges with well site 
operational schedules is presented in slide 5 of Hess Briefing for 
the EPA: NSPS OOOOb Safety, Malfunction & Repair Temporary Flaring 
Allowance. June 3, 2024. Slide Presentation.
---------------------------------------------------------------------------

    However, the EPA believes at this time that proposing to change the 
requirement to allow temporary routing to a flare or control device for 
up to 48 hours is likely to address most of the issues raised by the 
petitioners. We maintain that equipment needs for failures should be 
planned for in advance to minimize routing to a flare or control device 
(i.e., owners and operators should plan to have equipment on hand for 
failures on site), and that additional time beyond 48 hours should not 
be necessary to address issues at remote sites since these sites are 
typically accessible within a 24 hour period (except during certain 
conditions e.g., seasonal weather, road closures that may prevent 
operators from accessing the site). Therefore, we are proposing to 
double the time frame for which temporary routing to a flare or control 
device is allowed during situations where a malfunction or incident 
endangers the safety of operator personnel or the public, and during 
repair, maintenance including blow downs, a production test, or 
commissioning, from 24 hours per event to 48 hours per event. This 
timeframe is supported by API's survey, which found the average 
duration of temporary flaring was 46 hours per event.
    While the EPA is proposing to change the allowed duration for 
temporarily routing associated gas to a flare or control device from 24 
to 48 hours, we recognize that there is some information that could 
support retaining the 24-hour time frame. As noted above, the API 
survey indicated that 83 percent of the circumstances encountered that 
required temporary flaring were resolved in 24 hours or less. Further, 
Colorado 2 Colo. Code. Regs. sec. 4041:903 allow gas to be flared (or 
vented during an upset condition), but for a period not to exceed 24 
cumulative hours per event. In addition, information from New Mexico 
\24\ indicates that only 11 percent of the total volume of gas flared 
(from all sources, not only associated gas) results from flaring 
activities with durations greater than 8 hours. We request information 
and data on whether the proposed temporary flaring duration of 48 hours 
has the potential to increase the amount of primary or secondary 
emissions. The duration of flaring will vary by basin and by the reason 
for flaring. We request that any data on changes in emissions due to 
flaring specifically identify the basin, reasons for flaring, and 
duration of the temporary flaring. We request that commenters consider 
this information in submitting comments related to the proposed change 
to 48 hours. We also request additional information to support the 
proposal, or to support retaining the 24-hour period in the final rule.
---------------------------------------------------------------------------

    \24\ https://wwwapps.emnrd.nm.gov/OCD/OCDPermitting/Reporting/NaturalGasWaste/UpstreamNaturalGasWasteSummaryReportExpanded.aspx.
---------------------------------------------------------------------------

    While the EPA expects that the vast majority of temporary flaring 
situations can be addressed within the 48-hour timeframe proposed in 
these amendments, we recognize that incidents might not be resolved 
within 48 hours due to circumstances beyond an owner or operator's 
control. Examples of such ``exigent circumstances'' mentioned by the 
petitioners include road closures and seasonal weather that could 
prevent operators from accessing the site to conduct a necessary 
repair. As discussed above, EPA is not proposing to allow temporary 
flaring beyond 48 hours during such circumstances; however, we are 
soliciting comment on the need to allow routing to a flare or control 
device for up to 72 hours where a legitimate and supported ``exigent 
circumstance'' claim is made. We solicit comment on what would 
constitute an exigent circumstance and defining these incidences. 
Relatedly, we are soliciting comment on the potential ``exigent 
circumstances'' recordkeeping criteria explained above, and on when an 
``exigent circumstance'' claim should be sent to the Agency (in the 
annual report or otherwise). This longer time frame of up to 72 hours 
for special situations is consistent with the duration recommended by 
reconsideration petitioners. We acknowledge that such circumstances 
represent real-life scenarios that are beyond an owner or operator's 
control but seek more information on this as an option. See section 
III.A.3 of this preamble for more explanation on our solicitation for 
information.

B. Vent Gas Net Heating Value (NHV) Continuous Monitoring Requirements 
and Alternative Performance Test (Sampling Demonstration) Option for 
Flares and Enclosed Combustion Devices

    A summary of the relevant promulgated provisions being reconsidered 
related to the vent gas NHV continuous monitoring requirements and 
alternative performance test (sampling demonstration) option for flares 
and enclosed combustion devices is presented in section III.B.1, and 
specific concerns and supporting information provided by petitioners 
and other industry representatives are presented in section III.B.2 of 
this preamble. After consideration of the petitioners' concerns and 
supporting information, the EPA is proposing certain discrete changes 
to these particular requirements finalized in the March 2024 final 
rule. The proposed changes are presented in section III.B.3 of this 
preamble and the EPA's rationale for those proposed changes is 
presented in III.B.4 of this preamble.
1. Summary of Promulgated Provisions Being Reconsidered
    The EPA finalized compliance requirements for continuous monitoring 
and initial and periodic performance testing for flares and enclosed 
combustion devices in the March 2024 final rule. Of relevance to this 
proposal are the final requirements for those two control devices 
regarding the NHV monitoring requirements and alternative performance 
test (sampling demonstration) option. In the March 2024 final rule, 
with exceptions for catalytic vapor incinerators, boilers and process 
heaters, and enclosed combustors where temperature is an indicator of 
destruction efficiency, all flares and enclosed combustors must 
maintain the NHV of the gas sent to the device above a minimum NHV 
value if the combustion device is pressure-assisted or uses no assist 
gas. If an owner or operator uses a steam- or air-assisted enclosed 
combustion device or flare, the owner or operator must maintain the 
combustion zone NHV (NHVcz) above a minimum level. If the 
owner or operator uses an air-assisted enclosed combustion device or 
flare, the owner or operator must maintain the NHV dilution parameter 
(NHVdil) above a minimum level. The NHVcz and 
NHVdil parameter terms account for the reduction in heating 
value caused by the introduction of air or steam. These

[[Page 3742]]

terms ensure that the assist gas does not overwhelm the heating value 
provided by the vent gas to the point where proper combustion is no 
longer occurring. Owners or operators also have the option to apply to 
use an alternative test method that either demonstrates continuous 
compliance with the combustion efficiency limit or directly 
demonstrates continuous compliance with the NHVcz operating 
limit and, if applicable, the NHVdil operating limit.
    Associated gas from a well site affected facility was exempt from 
NHV monitoring (i.e., assumed to always have high NHV) under the March 
2024 final rule. For each enclosed combustor and flare used to control 
gases other than associated gas from a well site affected facility, the 
owner or operator must conduct continuous monitoring using a 
calorimeter, gas chromatograph (GC), or mass spectrometer (MS) in order 
to determine the NHV of the vent stream. As an alternative to 
continuous monitoring of NHV, the owner or operator may conduct a 
performance test to demonstrate the NHV of the vent stream consistently 
exceeds the applicable NHV operating limit in one of two ways: (1) 
Continuous sampling for 14 consecutive days plus ongoing (3 samples 
every 5 years) sampling, or (2) manual sampling (twice daily for 14 
consecutive days) plus ongoing (3) samples every 5 years) sampling. The 
minimum collection time for each individual manually collected sample 
must be at least one hour. If inlet gas flow is intermittent such that 
collecting 28 samples in 14 days is infeasible, an owner or operator 
must continue to collect samples beyond 14 days in order to collect a 
minimum of 28 samples. Owners or operators also have the option to use 
an alternative test method 25 26 that demonstrates 
continuous compliance with the combustion efficiency limit; if there 
are no values of the combustion efficiency measured by the alternative 
test method over the 14-day period that are less than 95 percent, the 
gas stream is considered to consistently exceed the applicable NHV 
operating limit and the owner or operator is not required to 
continuously monitor or conduct sampling of the NHV of the inlet gas to 
the enclosed combustion device or flare. Owners or operators of steam-
assisted and air-assisted enclosed combustors and flares also must 
monitor the vent gas and assist gas flow rates and calculate 
NHVcz and NHVdil in accordance with the 
provisions in 40 CFR 63.670 (i.e., the refinery maximum achievable 
control technology rule, or Refinery MACT). Alternatively, owners or 
operators of air-assisted flares may provide a one-time demonstration 
based on maximum air assist rates, minimum waste gas flow rates (based 
on back pressure regulator setting), and minimum NHV from the most 
recent sampling rather than continuously monitor vent gas and assist 
gas flow rates.
---------------------------------------------------------------------------

    \25\ Under the provisions outlined in 40 CFR 60.5412b(d) and 
60.5415b(f)(1)(xi), sources can request to use an ``equivalent 
method'' pursuant to 40 CFR 60.8(b)(2), or ``an alternative method 
the results of which [the Administrator] has determined to be 
adequate for indicating whether a specific source is in compliance'' 
pursuant to 40 CFR 60.8(b)(3). The EPA is currently accepting and 
reviewing applications for alternative (ALT) test methods for NHV 
monitoring in the oil and natural gas sector. See https://
www.epa.gov/emc/oil-and-gas-alternative-test-
methods#:~:text=The%20application%20portal%20can%20be,Air%20Emission%
20Measurement%20Center%20web page. Since the rule's publication date 
of March 8, 2024, two alternative test method requests have been 
approved by the EPA for use under NSPS subpart OOOOb: (1) ALT-156 
Alternative Test Method to monitor the NHV of the flare combustion 
zone at facilities Subject to NSPS OOOOb and (2) ALT-157 Alternative 
Test Method for determining NHV from gas sent to an ECD or Flare 
subject to NSPS OOOOb. A list of the EPA's approved alternative test 
methods can be found at https://www.epa.gov/emc/broadly-applicable-approved-alternative-test-methods.
    \26\ Per 40 CFR 60.8(b)(5), the EPA has more general authority 
to approve alternative test methods involving ``shorter sampling 
times and smaller sample volumes when necessitated by process 
variables or other factors.''
---------------------------------------------------------------------------

    Finally, as discussed in section II.B of this preamble, the EPA 
issued a letter on May 6, 2024, whereby the EPA clarified performance 
testing deadlines with respect to the alternative NHV sampling 
demonstration that owners or operators must meet in order to 
demonstrate compliance with the applicable NSPS subpart OOOOb emission 
standard. The EPA stated that as applied to the March 2024 final rule, 
affected sources that were new, modified, or reconstructed after the 
supplemental proposal (December 6, 2022), but before the rule's 
effective date of May 7, 2024, have 180 calendar days after the 
effective date of the rule to conduct performance (i.e., compliance) 
testing. For NSPS subpart OOOOb sources that are new, modified or 
reconstructed after the final rule's effective date of May 7, 2024, the 
applicable monitoring requirements (including the 14-day NHV 
performance test) must be completed within 180 calendar days after 
initial startup of the source.
2. Petitioners' Concerns and Supporting Information
    API and AXPC 27 28, TXOGA \29\, GPA Midstream \30\, and 
EIP \31\ raised issues in their petitions relating to the March 2024 
final rule requirements for the NHV compliance demonstration, which 
consists of either monitoring the NHV content of the vent gas on a 
continuous basis, or utilizing the alternative performance test option. 
The April and May 2024 API and AXPC petitions, May 2024 TXOGA petition, 
and May 2024 GPA Midstream Association petitions raised issues 
regarding the need for the NHV compliance demonstration, technical 
infeasibility of the demonstration, and compliance timing (including 
supply chain issues). The May 2024 EIP, et. al. petition contended that 
the EPA did not support its conclusion in the March 2024 final rule 
that initial assessments of flares and other control devices, in lieu 
of continuous monitoring, can capture the variability of NHV in the oil 
and gas sector, and that no sampling or monitoring of NHV is needed 
when only associated gas from wells is sent to control devices.
---------------------------------------------------------------------------

    \27\ April 2024 API and AXPC petition.
    \28\ May 2024 API and AXPC petition.
    \29\ May 2024 TXOGA petition.
    \30\ May 2024 GPA Midstream petition.
    \31\ May 2024 EIP, et al. petition.
---------------------------------------------------------------------------

a. Need for NHV Compliance Demonstration
    The April and May 2024 API and APXC and May 2024 GPA Midstream 
petitions state that vent gases in this industry are not expected to 
fall below the minimum NHV unless diluted by inert gases,\32\ and 
therefore the NHV requirements in the March 2024 final rule are 
unnecessary. The May 2024 GPA Midstream petition raised concerns with 
operations in the midstream and stated that waste gas streams routed to 
combustion devices have very high British thermal unit (Btu) values, 
when compared to the minimum NHV values finalized in the March 2024 
final rule, because these midstream gas streams consist of natural gas 
and field gas with NHVs typically in excess of 1,000 Btu/standard cubic 
feet (scf). Further, this petitioner stated that inert gases, such as 
nitrogen, are rarely used at midstream sources and any water in the gas 
is eliminated well before the control device. This petitioner also 
cited to prior responses to public comments

[[Page 3743]]

from the EPA which acknowledged the NHV of the vent gas to a flare in 
this sector is likely to be well above the minimum required NHV \33\ 
and questioned what it perceived as a change in the EPA's position \34\ 
in the March 2024 final rule. In a letter \35\ to the EPA dated July 
31, 2024, GPA Midstream provided additional information, not previously 
provided during the course of the prior rulemaking, regarding operating 
scenarios in midstream operations where vent gases may have a lower NHV 
than typical gathering, boosting, and processing operations. In this 
same letter, GPA Midstream also provided new NHV data from gathering, 
boosting, and processing vent gas streams routed to controls, along 
with four new operating scenarios for the EPA's consideration, where 
the NHV content in vent gas streams may be lower than normal:
---------------------------------------------------------------------------

    \32\ For the purposes of the NHV compliance provisions, inert 
gases (or inerts) are gases that do not readily undergo combustion. 
Inert gases consist of or contain high concentrations of nitrogen, 
carbon dioxide (CO2), water, or other compounds that have 
a net heating value of zero.
    \33\ See RTC, Response II-17-46 and II-17-47.
    \34\ See 89 FR 16966.
    \35\ GPA Midstream--EPA 06/24/24 Meeting Follow-Up. Re: Response 
to EPA Request for Additional Information regarding OOOOb GPA 
Midstream Net Heating Value Case Scenarios and Data. (Attachment 
Summarizing NHV Data Included as an Attachment). Hereinafter 
referred to as the ``July 2024 GPA Midstream Letter.''
---------------------------------------------------------------------------

    1. Combining acid gas removal (AGR) system amine regenerator still 
column vent gas with affected facility vent gas streams--GPA Midstream 
explained that AGR amine regenerator still column vent gases typically 
are routed to an individual control device due to the low flow rate, 
low pressure, and corrosive nature of the vent stream, and that the low 
NHV of the stream typically requires supplemental gas for proper 
control device operation. However, GPA Midstream explained it is 
possible to combine the still column vent gas with other vent gas 
streams, which would lower the NHV of the combined stream, primarily 
due to the high CO2 content of the still column vent gas.
    2. Combining glycol dehydration unit reboiler vent gas with 
affected facility vent gas streams without water removal--GPA Midstream 
explained that typically glycol dehydration unit reboiler vent gas is 
routed through a condenser to remove liquids (including VOC and water 
vapor) and then routed to a process or control device. However, it is 
possible to combine the glycol dehydration unit reboiler gas, without 
routing through a condenser, with other vent gases routed to common 
control. The high water content of the reboiler vent gas stream could 
lower the NHV of the combined vent gas streams.
    3. Use of inert gases and entrainment in affected facility vent gas 
stream--GPA Midstream explained that midstream operations usually do 
not employ the use of inert gases such as nitrogen because if a blanket 
gas is needed, its midstream operations use natural gas as it is 
readily available and compatible with control devices due to the high 
NHV. In instances where an inert gas such as nitrogen is used as a 
blanket gas, this could cause lower NHV of the vent gas stream.
    4. High water content in vent gas streams from storage vessels--
Finally, GPA Midstream explained that midstream operations employ the 
use of storage vessels for storing hydrocarbons and produced water, 
which typically have NHVs well above the thresholds required by the 
March 2024 final rule. However, it is possible that some production 
areas could have higher water content in the vent stream coming from 
the storage vessels, which would lower the NHV. GPA Midstream notes 
that in these cases, the high water content would increase the 
probability that the storage vessel emissions thresholds for 
applicability would not be exceeded. In any event, GPA Midstream 
explained that in such scenarios, the NHVs are still above the lower 
NHV thresholds of the rule.
    GPA Midstream summarized that midstream operators would be aware of 
the operating scenarios provided and should be allowed to use process 
knowledge to assess whether the NHV could not meet the requirements of 
the March 2024 final rule, and thus would require the use of 
supplemental gas.
    GPA Midstream also provided a new data set \36\ of sampled data and 
modeled data from midstream operations, stating that the data indicate 
that the vent gas streams are well above the NHV requirements of the 
rule and hence should not require continuous NHV monitoring. GPA 
Midstream further explained technical difficulties in collecting the 
data, which are described in section III.B.b of this preamble.
---------------------------------------------------------------------------

    \36\ July 2024 GPA Midstream Letter.
---------------------------------------------------------------------------

    The April 2024 API and AXPC petition referred to an NHV data set 
\37\ that they provided to the EPA after publication of the March 2024 
final rule which included over 22,000 data points from 18 operators 
across approximately 4,200 sites. The petitioners stated that this data 
set showed that more than 99.5 percent of the time NHV values were at 
least 800 Btu/scf and more than 99.9 percent of the time the NHV value 
was at least 300 Btu/scf. API and AXPC further stated that the results 
appeared consistent across five basins, representing 99 percent of the 
data. While some sources with multiple data points showed variability, 
the NHV was still well above 800 Btu/scf for those sources. API and 
AXPC stated that all NHV data scf in the survey were from 
known scenarios where large amounts of inert gas(es) are expected. The 
petitioners stated that operators know which scenarios or sites have 
the potential for large amounts of inert gases to reduce the NHV of 
vent streams below the required minimum; these known scenarios include: 
(1) Sites in fields using water or CO2 flood Enhanced Oil 
Recovery (EOR), and (2) produced water tanks not co-located with oil 
tanks in certain dry gas plays.
---------------------------------------------------------------------------

    \37\ API/AXPC-EPA 03/18/24 Meeting Follow-Up. Operator Survey: 
Net Heating Value. API-AXPC Meeting Slide Presentation to the EPA. 
(Attachment Summarizing NHV Data Included as an Attachment. Excel 
Sheet Provided of Analysis of NHV Data Provided by Operators: 
Supporting Data (Prepared by John Beath Environmental, LLC for API/
AXPC).)
---------------------------------------------------------------------------

    The April 2024 API and AXPC petition also included a letter from 
SPL, which stated it is the largest laboratory in the United States 
(U.S.) specializing in the analysis of hydrocarbon products, processing 
more than 225,000 natural gas samples each year. SPL stated that based 
on its direct experience analyzing thousands of vent gas samples from 
every major oil and gas producing region of the U.S. annually, it would 
be exceptionally uncommon for the NHV content of vent gas to fall below 
the threshold levels established by the March 2024 final rule. SPL 
explained that vent gases are exceptionally heavy gases (relative to 
air) that are typically depleted with respect to lighter hydrocarbon 
molecules such as methane and ethane, and enriched in molecules like 
propane, butane and pentane. As a result, SPL explained that these 
heavy gases have a lower vapor pressure (relative to a methane-enriched 
sales gas, for example) and therefore do not ``flash'' from the liquid 
hydrocarbon stream until the final stage of separation. The vendor 
provided NHV data for methane (909.4 Btu/ft\3\), propane, n-butane and 
n-pentane (2,315 Btu/ft\3\, 3,000 Btu/ft\3\ and 3,707 Btu/ft\3\ 
respectively).\38\ Therefore, SPL explained that, unless there is a 
source of inert gas diluting the vent gas stream (sources of inert gas 
could be added by design, or, due to leaking equipment), there should 
be no compositional reason the NHV of that gas would be under the 
threshold set by the EPA.
---------------------------------------------------------------------------

    \38\ See: GPA 2145--``Table of Physical Properties for 
Hydrocarbons and Other Compounds of Interest to the Natural Gas 
Industry.''
---------------------------------------------------------------------------

b. Technical Infeasibility
    The April and May 2024 API and AXPC petitions, May 2024 TXOGA

[[Page 3744]]

petition, and May 2024 GPA Midstream petitions raised new issues 
regarding the feasibility of conducting the sampling for the 
alternative NHV performance test (sampling demonstration), given the 
intermittent flow to control devices. The petitioners explained that in 
some cases, flow to the control device may occur for as little as a few 
minutes, making continuous monitoring or collection of single (or 28) 
one-hour samples impossible. The May 2024 TXOGA petition also explained 
that sampling equipment is not designed to operate in low temperatures 
or with all types of gases.
    The April 2024 API and AXPC petition pointed out that while the 
March 2024 final rule reduced the number of required samples from 240 
(as proposed in the December 6, 2022 supplemental rule) to 28, it did 
not address the feasibility of collecting the samples. API and AXPC 
also contended that extending the sampling duration from 10 to 14 days 
added time and costs to an already technically infeasible option. As 
noted above, these petitioners submitted information from SPL, a 
laboratory that stated that the minimum one-hour sampling requirement 
in the alternative performance test (sampling demonstration) option 
goes against traditional norms for the collection of natural gas grab 
samples and requires all sampling entities to deploy alternative 
strategies which are not currently available. SPL explained that 
typical methods for the collection of natural gas samples call for spot 
sampling techniques that procure gas on very short (seconds to minutes) 
timescales, but the one-hour requirement requires composite sampling 
techniques typically used in custody-transfer applications (and 
elsewhere) to be adapted to a more rugged and transportable setup. SPL 
suggested that the EPA allow sample collection methods such as those 
referenced in GPA 2166-22 instead. SPL also pointed out what it 
considered to be several issues with the use of Summa canisters for 
vent gas collection. SPL explained that Summa cannisters were designed 
primarily for atmospheric gas sampling and that in order to collect 1-
hour samples by Summa cannister, restrictive flow metering devices will 
be required, which rely on a restrictive orifice to meter the gas into 
the Summa cannister. SPL explained that the potentially wet and dirty 
nature of flare gas will rapidly foul these devices, resulting in 
errors in collection and potential contamination bias. Instead, SPL 
recommended that, for operators and laboratories to meet sample demand 
in a reasonable manner, single cavity stainless steel constant volume 
cylinders should be allowed for sample collection so long as they are 
maintained according to the requirements set forth in 43 CFR 3175 
(Onshore Oil and Gas Operations; Federal and Indian Oil and Gas Leases; 
Measurement of Gas).
    The May 2024 GPA Midstream petition explained that vent gas flow 
from midstream sources to control devices tended to be sporadic and at 
low pressure. They stated that intermittent flow was particularly an 
issue for storage vessels that either have low flows generally or have 
pressure control valves that only release short bursts of gas to 
control devices. GPA Midstream stated it is not possible to achieve the 
necessary flow rate for establishing a temperature limit, continuous 
monitoring, or one-hour sampling without adding gas pressure. It 
further explained that storage vessels will frequently be unable to add 
sweep gas because the necessary headspace is limited; in situations 
where facilities add gas, those situations will not be representative 
of normal operating conditions. In the July 2024 GPA Midstream letter, 
GPA Midstream provided further examples of sample collection issues. In 
addition to the availability of sampling ports, discussed below, GPA 
Midstream noted that closed vent systems (CVS) operate under a slight 
vacuum or close to atmospheric pressure and temperature, which can draw 
oxygen (O2) in with the vent stream sample. Also, because 
vent gas samples are obtained at atmospheric pressures, explained GPA 
Midstream, running the vent gas samples through the GC upon capture 
causes issues due to liquids (e.g., water) condensing during analysis, 
which often requires repairs to the GC.
    The April 2024 API and AXPC petition contended that NHV monitoring 
is not required in existing State regulations governing upstream flares 
and combustion emissions control devices and that upstream operators 
are not currently conducting NHV monitoring for operational or other 
non-regulatory reasons.\39\ Thus, the petitioners argued that the NHV 
monitoring at upstream flares and combustion emissions control devices 
has not been demonstrated to be feasible or cost-effective.
---------------------------------------------------------------------------

    \39\ API and AXPC specifically point to Colorado and New Mexico 
as examples.
---------------------------------------------------------------------------

    The April 2024 API and AXPC petition also expressed concerns that 
the Refinery MACT-based NHVcz and NHVdil 
requirements for devices which use steam- and air-assist and perimeter-
assist air, respectively, are overly burdensome because well sites, 
central production facilities, and compressor stations are 
fundamentally different than petroleum refineries. The petitioners 
explained that the oil and natural gas production sector does not 
operate at steady state conditions and equipment design must be 
tailored to the conditions and fluid compositions supplied by the 
reservoir. They added that hydrocarbon fluids (including oil, 
condensate, and produced water) and natural gas are located thousands 
of feet below the surface and must flow to the surface for separation. 
API and AXPC explained that separation occurs in either a two- or 
three-phase separator with intermittent pulses of produced water sent 
from the bottom of the separator to its storage vessel, hydrocarbon 
liquids from the middle to its storage vessel, and natural gas off the 
top of the separator to the gathering system. These petitioners further 
explained that as production declines, management of liquids can mean 
that flow to the storage vessel can vary from essentially zero to high 
flow rates and quickly back to zero rapidly and often. According to the 
petitioners, the same is true for how vapors from the storage vessel 
will be expected to flow to a control device since emissions occur from 
flashing and working losses as liquid periodically flows into the 
storage vessel from the separator. The petitioners explained that this 
highly variable, non-steady state flow requires equipment to be sized 
much larger than ideal steady state conditions would dictate and makes 
flow measurement infeasible. The petitioners also provided that the 
cost for Refinery MACT controls and monitoring equipment at refineries 
are $1 million or more, with major ongoing costs. The petitioners 
explained that these costs will be much greater at upstream facilities 
without the necessary utilities and instrumentation resources available 
for a large complex facility such as a refinery and it is unclear 
whether instrumentation that is available that would work reliably 
under these varying operating conditions.
    The April and May API and AXPC and May 2024 GPA Midstream petitions 
also raised issues with the alternative test method approval process, 
stating that alternative test methods are costly to implement (and 
unlikely to be used by small operators) and take time for agency 
approval (and which is related to issues regarding compliance timing 
discussed in section IV.B.2.c of this preamble). The May 2024 GPA

[[Page 3745]]

Midstream petition requested that the EPA revise the March 2024 final 
rule to allow alternative test methods for air and steam-assisted 
combustion devices, such as Video Imaging Spectro-Radiometry (VISR), as 
the March 2024 final rule preamble and regulatory text conflict with 
respect to what is allowable. Specifically, the petitioner cited to 89 
FR 16968, which indicates that ``an owner or operator could request an 
alternative test method to use a technology such as VISR that 
continuously monitors combustion efficiency or a technology such as 
Simplified VISR that continuously monitors NHVcz and 
NHVdil,'' but noted that the associated monitoring 
requirements at 40 CFR 60.5417b(d)(8)(iii)(H) appear to not allow 
alternative test methods to continuously monitor NHVcz and 
NHVdil.
    The May 2024 GPA Midstream petition also stated that the EPA should 
allow for compliance demonstration alternatives. This petitioner 
explained that design evaluations using process simulation software 
will be more than sufficient for midstream sources to document that 
waste streams consistently exceed the EPA's minimum NHV values. The 
petitioner repeated prior comments to the EPA \40\, that owners and 
operators can perform and document source-specific design evaluations 
to demonstrate that waste gas streams will consistently exceed the 
required minimum NHV thresholds in a manner similar to the evaluations 
used for condensers and carbon absorption units under 40 CFR 
60.5413b(c). If the EPA does not allow for compliance demonstration 
alternatives, the petitioner requested that the EPA allow for 
alternative sampling locations. In the July 2024 GPA Midstream letter, 
GPA Midstream explained that prior to NSPS OOOOb, operators were not 
required to collect NHV data because process knowledge would support 
the vent stream as having a high NHV. Because of this, CVS were not 
designed to include sampling ports. In addition to the compliance 
timing reasons discussed in section IV.B.2.c of this preamble relating 
to ``hot taps,'' the petitioner requested that the EPA allow sampling 
from existing access points, such as thief hatches, which would avoid 
the compliance timing issues, unnecessary costs, and creation of a new 
opening that would be another potential source of fugitive emissions. 
The petitioner also requested that owners or operators be able to draw 
samples from storage vessel headspace, as there are always vapors 
present in the vessel headspace and it will be representative of the 
vent gas routed to the control devices.
---------------------------------------------------------------------------

    \40\ See GPA Midstream Comments on the Supplemental Proposed 
Rule (February 13, 2023) at 42-43. See Docket ID No. EPA-HQ-OAR-
2021-0317.
---------------------------------------------------------------------------

    The May 2024 API and AXPC petition also requested that the EPA 
require a re-evaluation of the of the vent gas stream NHV only when 
there are process or equipment changes that could result in a lowering 
of the NHV and requested that the EPA provide guidance regarding the 
analytical methods required for NHV sampling. The petitioners noted 
that the March 2024 final rule requires the use of American Society for 
Testing and Materials (ASTM) Method D1945-14 for NHV analysis but 
stated that this method is not widely available for well sites, 
centralized production facilities, compressor stations, and gas plants 
since it evaluates components not typically found in vent gas from 
these operations (e.g., helium). The petitioners requested that the EPA 
revise the March 2024 final rule, or at a minimum provide guidance, to 
allow the use of GPA 2261 and other appropriate alternative methods to 
measure NHV. In support of this, the petitioner provided information 
from SPL, which stated that ASTM D1945-14 is not widely available and 
will require additional time for method development, as well as 
purchase or modification of equipment.
c. Compliance Timing
    In addition to the compliance timing issues discussed above 
relating to alternative test method approval and test method capability 
development, the May 2024 GPA Midstream petition raised the issue that 
the March 2024 final rule does not provide adequate time to conduct the 
testing after such an approval is granted. The petitioner explained 
that while 40 CFR 60.5412b(d)(1) through (5) provides requirements for 
how the alternative test is performed, it provides no period of time by 
which it should be performed, unlike 40 CFR 60.5413b(b)(5)(i) which 
specifies that performance testing is required within 180 days after 
initial startup. The petitioner further notes that unlike continuous 
monitoring, which can be installed prior to startup of a new source, 
the alternative testing protocol requires the combustion device to 
already be operating in order to determine the destruction efficiency 
and inspect of visible emissions. The petitioner is concerned that the 
March 2024 final rule can be read so that any period of operation 
before or during the alternative testing (dating back to December 2022 
for modified sources) may be a deviation. The petitioner requests that 
the EPA allow 30 days after startup to perform alternative testing.
    The May 2024 TXOGA and April 2024 API and AXPC petitions expressed 
concerns about the availability of sampling vendors that can perform 
the sampling. The May 2024 TXOGA petitioner also pointed out that 
finding viable sampling periods cannot be predicted due to the 
intermittent flow to the devices. The April 2024 API and AXPC petition 
estimated that a single sampling crew can typically visit no more than 
two or three sites in a day due to the geographically dispersed nature 
of upstream operations. This same petitioner provided statements from 
SPL stating that the number of samples required would be greater than 
the capacity of labs to collect and process in the 60-day window and 
that there are not enough gas chromatographs, sample cylinders, and 
human resources to make compliance within 60 days a possibility.
    The May 2024 GPA Midstream petition raised concerns with the 
feasibility of meeting compliance timelines for installation of 
sampling ports. The petitioner stated that the EPA has underestimated 
the number of sources that would be considered ``modified'' under the 
Final Rule, resulting in the need to install monitors and sampling 
ports on thousands of sources in an impracticably short time.\41\ The 
petitioner stated that it will take owners and operators several months 
to procure continuous monitoring equipment and installation will take 
additional time. The petitioner provided purchase quotations from 
vendors which indicated that calorimeters would take eight to 12 weeks 
for delivery and continuous monitoring devices would take up to 26 
weeks; installation would require an additional 2 to 3 weeks. 
Additional concerns expressed by the May 2024 GPA Midstream petition 
were that installation of monitoring equipment or sampling ports on 
existing control devices requires specialized ``hot tap'' work, which 
they stated cannot be accomplished across the industry prior to the 
deadline for compliance demonstrations, due to a limited number of 
qualified contractors and the

[[Page 3746]]

need to properly time unit shutdowns for the hot tap work.
---------------------------------------------------------------------------

    \41\ See GPA Midstream Comments on Supplemental Proposed Rule at 
37-38 (need for additional compliance time for storage vessels); 42 
(discussing supply chain shortages contributing to long lead times). 
See Docket ID No. EPA-HQ-OAR-2021-0317.
---------------------------------------------------------------------------

d. Other
    The May 2024 EIP, et. al. petition contended that the EPA did not 
support the March 2024 final rule conclusion that initial assessments 
of flares and other control devices, in lieu of continuous monitoring, 
can capture the variability of NHVs in the oil and gas sector and 
asserted that no sampling or monitoring at all is needed when only 
associated gas from wells is sent to control devices.
3. Summary of Proposed Changes
    The EPA is proposing to revise numerous aspects of the NHV 
monitoring and testing provisions in the March 2024 final rule. The EPA 
is proposing to expand the streams that are exempt from monitoring due 
to high NHV content to include unassisted flares or enclosed combustion 
devices at new sources and to include unassisted, air-assisted, and 
steam-assisted flares or enclosed combustion devices at existing 
sources. We are proposing that the NHV monitoring that is currently 
required should continue to be required for all pressure-assisted, air-
assisted, and steam assisted flares or enclosed combustion devices at 
new sources and for pressure-assisted flares or enclosed combustion 
devices at existing sources. We are proposing to remove the general 
exemption from NHV monitoring for associated gas from well site 
affected facilities for any control device. For flares or enclosed 
combustion devices that are subject only to a minimum NHV content in 
the vent gas of 200 Btu/scf or 300 Btu/scf, we are proposing to require 
NHV monitoring only in cases where inert gases are added, or for other 
miscellaneous scenarios which decreases the NHV content of the inlet 
stream gas to the enclosed combustion device or flare. These known 
operational scenarios include combining AGR system amine regenerator 
still column vent gas with affected facility vent gas, combining glycol 
dehydration unit reboiler vent gas with affected facility vent gas 
streams without water removal, high water content in vent streams from 
certain storage vessels, and EOR sites in fields using water or 
CO2 flooding. The EPA is proposing recordkeeping and 
reporting to indicate whether the flare or enclosed combustion device 
receives inert gases or other streams which may lower the NHV of the 
combined stream, and if so, a description of the operating scenario(s) 
which may lower the NHV of the combined stream through the introduction 
of those inert gases or other streams.
    In addition, when an owner or operator opts to meet the NHV 
compliance demonstration by conducting the alternative performance test 
via the NHV grab sampling option, the EPA is proposing revisions to 
clarify that sampling may be conducted on ``the inlet gas which is 
routed to the enclosed combustion device or flare'' [emphasis denotes 
proposed revision]. The EPA intends that this revised phrasing will 
clarify that sampling upstream of the inlet to the control device is 
allowed, provided that the sample is representative of the gas inlet to 
the control device. For example, sampling may be conducted from a 
location on the control device piping header, provided the sampling 
location is downstream of all waste gas inlets into the header. The EPA 
is proposing to clarify that the NHV of the vent stream shall be 
determined in Btu/scf, where standard conditions are 20 degrees Celsius 
([deg]C), not Btu per pound (Btu/lb). If the composition is determined 
in weight percent, those concentrations can be used, but they will need 
to be converted to volume percent (equivalent to mole percent) based on 
the molecular weight of the constituents. Other changes in this 
proposal include specifying that the 14-day period for the performance 
test (sampling demonstration) option shall be consecutive operating 
days and that for the purposes of determining the hourly average for 
continuous samples, the average shall be a block hourly average. The 
EPA is not proposing to amend the sampling frequency (i.e., 2 samples 
per day for 14 days with an ongoing demonstration of 3 samples every 5 
years) for the performance test (sampling demonstration) option for 
neither NSPS OOOOb nor EG OOOOc. However, the EPA is proposing to allow 
for breaks for weekends and holidays which may occur during the 14-day 
sampling period, such that the 14 days do not have to be consecutive. 
The EPA is also proposing to retain the one-hour minimum sampling time 
for the twice daily samples, except in cases where low or intermittent 
flow makes one-hour sampling infeasible. In such a case, the EPA is 
proposing to allow less than one-hour sampling times and proposing that 
the sampling time used and the reason for the reduced sampling time 
must be documented and reported. The EPA is proposing to more clearly 
allow the use of the sampling methodology alternative to continuous 
monitoring in 40 CFR 60.5417b(d)(8)(iii) for all types of air and steam 
assisted flares or enclosed combustion devices. The EPA is proposing 
these same changes in both NSPS OOOOb and EG OOOOc.
    In addition, for NSPS OOOOb, the EPA is proposing to retain the 
NHVcz and NHVdil monitoring requirements, but 
more clearly including the provisions at 40 CFR 60.5417b(d)(8)(vi) to 
allow the use of approved alternative test methods as provided in 40 
CFR 60.5412b(d)(1)(i) and (ii) for continuous monitoring of 
NHVcz and, if applicable, NHVdil. We are also 
proposing to more fully delineate in 40 CFR 60.5417b(d)(8)(iv) when 
flare flow or assist rates are not required to be monitored. On the 
other hand, for EG OOOOc, the EPA is proposing to remove the 
requirement to comply with and conduct monitoring for NHVcz 
and NHVdil for air- and steam-assisted enclosed combustion 
devices and flares used for existing sources. This series of proposed 
revisions in EG OOOOc include changes in the initial compliance 
requirements for air- or steam-assisted enclosed combustion devices or 
flares in 40 CFR 60.5412c, the continuous compliance requirements for 
these control devices in 40 CFR 60.5415c, and the continuous monitoring 
requirements for these control devices in 40 CFR 60.5417c. We are 
proposing under EG OOOOc that air- or steam-assisted enclosed 
combustion devices or flares must meet a minimum NHV in the vent gas of 
300 Btu/scf.
4. Basis for Proposed Changes
a. Proposed Revisions to Inlet Gas Streams Exempt From Monitoring
    As discussed in section III.B of this preamble, based on new 
information provided by petitioners regarding NHV characteristics of 
sample streams, the EPA is proposing changes to the requirements in the 
March 2024 final rule that would, if finalized, expand the scope of the 
exclusion for the NHV continuous monitoring requirements and 
alternative performance test (sampling demonstration) option so that 
the following control devices would not be required to make any such 
demonstration: unassisted flares or enclosed combustion devices at a 
new source and for unassisted, air-assisted, or steam-assisted flares 
or enclosed combustion devices at existing sources. New data submitted 
in the April 2024 API and AXPC petition demonstrated that, for over 
22,000 NHV data points, 99.5 percent of those data points showed that 
the NHV was at least 800 Btu/scf and more than 99.9 percent of those 
data points showed that NHV was at least 300 Btu/scf. Notably, these 
data were consistent across different

[[Page 3747]]

basins.\42\ Data supplied in the July 2024 GPA Midstream letter 
supported their prior petition submittals that gas streams in the 
midstream consist of natural gas and field gas with NHV values greater 
than 1,000 Btu/scf, with the exception of certain streams in which 
inert gases or other known low-NHV streams were added. Because these 
new data appear to demonstrate that the NHV of the vent gas is 
consistently well above the 200 or 300 Btu/scf vent gas requirements 
for these control devices when inerts are not present, and because 
there are no combustion zone or dilution parameters for these control 
devices, the EPA is proposing to determine that an expanded exclusion 
from the monitoring requirements is appropriate.
---------------------------------------------------------------------------

    \42\ 99 percent of the data were from five basins: Permian, 
Anadarko, Gulf Coast (Eagleford), Williston (Bakken), and Powder 
River. See March 18, 2024, API/AXPC Slides in Docket ID No. EPA-HQ-
OAR-2024-0358.
---------------------------------------------------------------------------

    While we previously excluded monitoring for associated gas from the 
NHV compliance demonstration requirements, some petitioners have now 
identified instances where the NHV for associated gas streams could be 
compromised. Specifically, the use of water or CO2 flooding 
EOR could introduce significant inerts as part of the associated gas 
produced and thereby lower NHV of the associated gas. We find the 
information presented by the petitioners compelling and therefore 
propose to conclude that the March 2024 final rule's exclusion of 
associated gas from the NHV compliance demonstration requirements is 
overly broad. Because the definition of associated gas in the March 
2024 final rule does specifically exclude these inert gases that may be 
released with the natural gas during the initial stage of separation 
after the wellhead, there are cases where associated gas can have high 
levels of inerts and low NHV. Therefore, we are proposing to remove 
this exclusion for associated gas in its entirety. The proposed removal 
of this exclusion would impact pressure-assisted flares and enclosed 
combustion devices at both new and existing sources and air- and steam-
assisted flares and enclosed combustion devices at new sources.
    The EPA is not proposing to exclude pressure-assisted flares or 
enclosed combustion devices from the NHV compliance demonstration 
requirements. For pressure-assisted flares or enclosed combustion 
devices, the required minimum NHV of 800 Btu/scf is not significantly 
higher than the NHV of methane, which is 896 Btu/scf (using standard 
conditions of 68 [deg]F (20 [deg]C); this value is lower than the value 
provided by SPL because they used 60 [deg]F as standard conditions). 
Therefore, sources that contain primarily methane would not require 
much dilution from inert components (e.g., nitrogen, CO2, or 
air) to be below the 800 Btu/scf NHV threshold for pressure-assisted 
flares or enclosed combustion devices. While the data provided by 
petitioners indicated that the majority of samples had NHVs above 800 
Btu/scf, we find that it is much easier for the NHV in the vent gas 
samples from these control devices to decrease and approach the 800 
Btu/scf NHV threshold and that, therefore, continuous NHV monitoring or 
an alternative performance test (sampling demonstration) is still 
warranted for pressure-assisted flares or enclosed combustion devices. 
Accordingly, we are proposing to retain the requirement that, as 
currently required in the March 2024 final rule, pressure-assisted 
flares must either continuously monitor NHV or conduct the 14-day 
performance test sampling demonstration in order to ensure that the 
gases sent to those control devices have NHVs well above the regulatory 
threshold.
    For reasons described in section III.B.4.d of this preamble, the 
EPA is proposing to retain the NHVcz and NHVdil 
requirements for air- and steam assisted flares for sources subject to 
NSPS subpart OOOOb. Because these parameters are not only dependent on 
the NHV of the vent gas but also on the flow rate of the vent gas and 
the assist gas, we propose that the NHV demonstration is necessary 
(when continuous monitoring is not used) to determine a minimum NHV to 
use in the assessments under 40 CFR 60.5417b(d)(8)(iv) and in the 
calculation of the NHVcz and NHVdil parameters in 
40 CFR 60.5417b(d)(8)(vi).
    As demonstrated by the July 2024 GPA Midstream data set, the 
addition of inert gases or streams from amine units or produced water 
tanks can decrease the NHV content of the gas stream to the point that 
the minimum NHV thresholds for non-pressure-assisted flares or enclosed 
combustion devices may not be achieved. In addition to sources of inert 
streams previously identified in the March 2024 final rule (i.e., 
streams from compressors in acid gas service and streams from EOR 
facilities), the July 2024 GPA Midstream letter explained that other 
operating scenarios can result in the addition of low-Btu value streams 
into the vent gas stream, which lowers the overall NHV for the vent 
stream. Therefore, we are proposing to require NHV monitoring for 
unassisted flares and enclosed combustion devices at new sources and 
for unassisted, air-assisted, and steam-assisted flares and enclosed 
combustion devices at existing sources in cases where there are 
contributions from inerts. In the example cases provided in section 
III.B. of this preamble, the EPA expects that these operational 
scenarios can be easily validated through the physical presence (or 
absence) of process equipment, process piping, engineering analysis, or 
process flow diagrams in order to determine when the owner or operator 
should monitor the NHV of the stream. For example, in the case of the 
AGR system amine regenerator still column vent gas, it would be easy to 
trace process piping to determine if the vent stream was routed to a 
dedicated control device or was combined with affected facility vent 
gas streams. Similarly, for the glycol dehydration unit reboiler vent 
gas, the lack of a process condenser would indicate that higher water 
content (and lower Btu) reboiler vent gas streams was combined with 
affected facility vent gas streams. The use of nitrogen as a blanket 
gas can be readily determined through the presence of nitrogen storage, 
supply systems, and process piping. Finally, regarding vent streams 
from storage tanks with higher water content, the EPA expects that 
tanks with water content high enough to depress overall NHV values 
typically would not meet the applicability thresholds of the rule and 
would not be combined with other vent streams routed to an enclosed 
combustion device or flare. However, when gas streams from produced 
water tanks are vented to control, vent lines from these tanks can be 
traced to identify sources that require monitoring or sampling.
    Regarding the concerns raised in the May 2024 EIP, et. al. 
petition, since we are proposing to remove the general monitoring 
exemption for when the only inlet gas stream to the enclosed combustion 
device or flare is associated gas from a well affected facility, we 
directly resolve one of the issues raised in that petition. We consider 
the data submitted by the industry petitioners to support the proposed 
exemption from monitoring for flares and enclosed combustion devices 
subject to a vent gas NHV requirement of 200 or 300 Btu/scf (and not 
subject to NHVcz and NHVdil requirement) when no 
inerts are present because the results were consistently much higher 
than these levels. The May 2024 EIP, et. al. petition also contended 
that the EPA did not support its conclusion in the March 2024 final 
rule that initial assessments of flares and other control devices, in 
lieu of continuous monitoring, can capture the

[[Page 3748]]

variability of NHV in the oil and gas sector. We consider the data 
submitted by the industry petitioners also supports that the NHV 
demonstrations required for pressure-, air-, and steam-assisted control 
devices would be adequate data to show that the NHV from those 
demonstrations is well above the limits required by the rule and that 
continuous monitoring is not needed. When inerts are added 
intermittently or process operations change that may lower the NHV, the 
proposed standards require re-demonstration with a new 14-day sampling 
effort. The new demonstration would consider the variability associated 
with these operations and determine a reasonable lower-range value to 
use in the compliance assessments. As such, we propose to find that the 
sampling requirements, with the revisions proposed, are robust and 
sufficient for the demonstration and that continuous monitoring is not 
needed when the demonstration shows the NHV value of the gas stream 
being controlled is sufficiently high, when considering the range of 
vent gas and assist gas flow rates, to meet the required standards.
    The EPA is also requesting comment on the proposed removal of the 
associated gas monitoring exemption and the proposed requirement for 
continuous measurement or sampling requirements for pressure-assisted 
flares and enclosed combustion devices at new and existing sources and 
for air- and steam-assisted flares or enclosed combustion devices at 
new sources. The EPA is requesting comment on whether there are other 
known process or upset condition scenarios which may introduce inert 
gases or other low-Btu streams into affected facility vent gas streams, 
resulting in NHV values which could be below the thresholds in the 
March 2024 final rule for flares and enclosed combustion devices 
subject to the vent gas NHV requirements of 200 or 300 Btu/scf and 
necessitating a determination of the NHV of the combined stream(s). The 
EPA also is requesting comment on how the EPA can determine (e.g., the 
presence or absence of certain process equipment or piping 
configurations) that these scenarios are present at an affected 
facility and, therefore, require NHV continuous monitoring or the use 
of the sampling option to demonstrate that the mixed gas stream has 
sufficient NHV content to afford proper combustion efficiencies.
b. Sampling Location and Duration for the Alternative Performance Test
    The EPA is reconsidering the requirements in the March 2024 final 
rule regarding the sampling duration for the alternative performance 
test (sampling demonstration) option for the NHV compliance 
demonstration, and is proposing to allow for shorter sampling times 
when it is technically infeasible to collect a grab sample for a 
minimum of one hour. While the March 2024 final rule included 
provisions for sampling periods of longer than 14 days (where needed) 
to collect a total of 28 samples, and the general provisions in 40 CFR 
60.8(b)(5) also allow for ``shorter sampling times and smaller sample 
volumes when necessitated by process variables or other factors,'' the 
EPA finds compelling the petitioners' arguments and newly presented 
supporting information regarding the potential instances of 
intermittent flow of gas streams, which makes sampling for one hour 
technically infeasible in those cases (e.g., intermittent flow from 
sources with low pressure). As such, the EPA finds it appropriate to 
propose additional flexibility in the final rule to fully address these 
intermittent flow situations. Therefore, the EPA is proposing that 
sampling must be conducted for a minimum of one hour, when technically 
feasible. When it is not technically feasible to collect the sample for 
a minimum of one hour, the owner or operator should collect the sample 
for as long as possible, up to one hour. For samples taken during low 
or intermittent flow events, the collection time and the reason for not 
obtaining a full one-hour sample must be documented and reported with 
the NHV sampling results. We request comment on the actual duration of 
flow that is achievable in practice for those cases where sampling for 
one hour is technically infeasible on low pressure and intermittent gas 
streams, and why a one hour sample would be technically infeasible for 
those cases.
    Regarding the location for sampling, the EPA notes that, according 
to the March 2024 final rule, the sample must be taken of the inlet gas 
to the control device, but the gas need not be taken directly at the 
inlet of the control device. We consider a sample within the control 
device header system in a location after all vent streams sources have 
been added to the control device header as an inlet gas sample. While 
the EPA recognizes petitioners' concerns with installing sampling ports 
or ``taps'' on these source types, the March 2024 final rule does not 
specify a physical location where the sampling must occur. The EPA 
therefore does not believe it is necessary to specify that sampling may 
occur at another ``representative'' location or specify such 
``representative'' locations. The EPA also notes that the General 
Provisions in 40 CFR part 60 include procedures for alternatives to 
monitoring, including alternative locations for monitoring, ``when the 
owner or operator can demonstrate that installation at alternate 
locations will enable accurate and representative measurements'' \43\--
these provisions already address site-specific issues with conducting 
the alternative performance test (sampling demonstration) option. 
Accordingly, the EPA is proposing not to change the current provisions 
in the March 2024 final rule regarding sampling location for the NHV 
grab sample option.
---------------------------------------------------------------------------

    \43\ Per 40 CFR 60.5417b(d), requests for approval to monitor 
different monitoring parameters can be made under the Alternative 
Monitoring Plan (AMP) provisions in 40 CFR 60.13(i).
---------------------------------------------------------------------------

c. Methodologies for Compositional Analysis of the Gas Stream
    The EPA is reconsidering the requirements in the March 2024 final 
rule which limited the test method available for determining the 
compositional analysis of the gas stream to ASTM-D1945-14 (R2019). The 
EPA recognizes that other rules in which vent gases are analyzed, such 
as 40 CFR part 63 subpart CC (Refinery MACT) and the Greenhouse Gas 
Reporting Program (GHGRP) rule allow the use of other test methods. The 
EPA is soliciting comment to expand the use of similar consensus-based 
standards (e.g., GPA 2166 and GPA 2261) to consider if these additional 
available methods would alleviate petitioners' concerns that ASTM-D1945 
is not widely available and that testing laboratories do not have the 
capacity currently to enable its use.
    Regarding the units in which NHV is determined as prescribed in the 
March 2024 final rule, the EPA does not disallow the use of measurement 
methods that determine concentrations in terms of weight fractions, but 
the weight fractions must be converted to volume fractions because the 
calculations referenced therein from part 63 use Btu/scf (not Btu/lb). 
Therefore, the EPA is not proposing to change the units in the March 
2024 final rule, but rather proposing to clarify that NHV for 
individual components must be determined in units of Btu/scf consistent 
with the existing specification using published values of the component 
NHV per mole at 25 [deg]C and 1 atmosphere and using 20 [deg]C as the 
standard temperature for determining the volume corresponding to one 
mole of vent gas. We noted that SPL reported

[[Page 3749]]

the NHV of common constituents in vent gas streams at the incorrect 
temperature. Therefore, we are proposing to clarify that the standard 
temperature for 40 CFR part 60 (at 40 CFR 60.18(f)(3)) is 20 [deg]C and 
that the NHV values must be determined at this standard temperature. 
These clarifications are proposed to ensure the NHV determinations are 
conducted consistently and accurately. The EPA is requesting comment on 
the proposed clarifications of the NHV units of measure and calculation 
procedures.
    We are also proposing to clarify that Tedlar bags may be used to 
satisfy the grab sampling requirements, provided that the Tedlar bag 
qualifies as an ``evacuated container'' as prescribed by section 
8.2.1.1 of EPA Method 18. We request comment on the need to clarify 
that Tedlar bags can be used and the limitation proposed on when Tedlar 
bags can be used.
d. NHVcz and NHVdil for Air- and Steam-Assisted 
Flares and Enclosed Combustion Devices at Existing and New Sources
    The EPA is proposing to retain the NHVcz and 
NHVdil requirements for air- and steam assisted flares for 
sources subject to NSPS subpart OOOOb because, as noted in the November 
2021 Proposal (86 FR 63246; November 15, 2021), the EPA had received 
some data indicating air-assisted and steam-assisted flares have been 
found operating outside of the conditions necessary to achieve at least 
98 percent control efficiency on a continuous basis. We disagree with 
petitioners that these NHV-related parameters are not appropriate for 
assisted flares in the oil and gas industry because we had evidence of 
poor-performing assisted flares in the oil and gas industry. The EPA 
therefore proposes to conclude (as in the March 2024 final rule) that 
sufficient evidence exists demonstrating poor destruction efficiencies 
due to over-assisting a flare or enclosed combustion device, such that 
NHV compliance demonstrations are necessary to show that these 
particular control devices are meeting the requisite efficiency. The 
EPA requests comment on the proposed retention of the NHVcz 
and NHVdil provisions for new sources. The EPA is also 
requesting comment on whether the NHVdil parameter is 
appropriate for enclosed combustion devices with perimeter assist air 
and the appropriate effective diameter to use in the calculation of 
NHVdil, if it is retained, particularly for devices with 
multiple burner tips within the enclosed combustion device.
    Regarding petitioner GPA's statement that 40 CFR 
60.5417b(d)(8)(iii)(H) appears to not allow alternative test methods to 
continuously monitor NHVcz and NHVdil, we note 
that the provisions at 40 CFR 60.5417b(d)(8)(iii) are specific to the 
14-day alternative performance test (sampling demonstration) option and 
do not apply to continuous monitoring. We did not include provisions 
for a 14-day demonstration using continuous monitoring of 
NHVcz and NHVdil because assist rates could be 
changed and alter the control device's performance. Continuous 
monitoring using alternative test methods is expressly provided for in 
40 CFR 60.5412b(d) and 60.5415b(f)(1)(xi). Additionally, we propose to 
clarify in 40 CFR 60.5417b(d)(8)(vi) that continuous monitoring of 
NHVcz and, if applicable, NHVdil using an 
approved alternative method as provided under 40 CFR 60.5412b(d)(1)(i) 
and (ii) is allowed and that, when using this alternative test method, 
you are not required to monitor NHV of the vent gas as specified in 
paragraph (d)(8)(ii) of this section or monitor flow rates as specified 
in paragraph (d)(8)(vi) of this section provided you can demonstrate 
that the maximum flow rate to the flare cannot cause the flare tip 
velocity to exceed 18.3 meter/second (60 feet/second). The EPA requests 
comment on the proposed clarifications when using the alternative test 
method to demonstrate continuous compliance and requests comment on 
whether and how such monitoring could be used as part of the 14-day 
sampling demonstration.
    With respect to the monitoring requirements for NHVcz 
and NHVdil for air- and steam-assisted flares at new 
sources, the EPA acknowledges the petitioners' concerns but is not 
proposing significant changes to this requirement for new sources 
subject to NSPS subpart OOOOb. However, in reviewing these requirements 
we note that the requirements in 40 CFR 60.1547b(d)(8)(vi) reference 
NHV determinations using the lowest NHV result of the sampling 
demonstration in 40 CFR 60.1547b(d)(8)(iii), but 40 CFR 
60.1547b(d)(8)(iii) did not have provisions for steam-assisted nor for 
certain air-assisted flares or enclosed combustion devices. Therefore, 
we are proposing to clarify that 40 CFR 60.1547b(d)(8)(iii) can be used 
for any steam- or air-assisted flare or enclosed combustion device, and 
that the effective vent gas NHV to allow the use of the demonstration 
is 300 Btu/scf when using continuous 14-day sampling or 360 Btu/scf 
when using the 14-day grab sampling approach. This revision in 40 CFR 
60.1547b(d)(8)(iii) is necessary considering the calculation provision 
in 40 CFR 60.1547b(d)(8)(vi) and corrects an unintended error in the 
March 2024 final rule. The EPA requests comment on the use of the 
proposed use of the 14-day sampling demonstration in 40 CFR 
60.1547b(d)(8)(iii) for air- and steam-assisted flares, particularly 
those at new sources subject to NHVcz and NHVdil 
requirements.
    With the alternative sampling provisions being proposed in 40 CFR 
60.5417b(d)(8)(iii) and the assessments outlined in 40 CFR 
60.5417b(d)(8)(iv), we expect few facilities will have to install 
continuous monitoring systems. Since monitoring is necessary to ensure 
proper operation of these flares at new sources, and considering the 
monitoring options provided by the proposed revisions will afford 
sources additional flexibility when compared to the March 2024 final 
rule, we are retaining the NHVcz and NHVdil 
requirements in NSPS subpart OOOOb.
    A provision to conduct monitoring for NHVcz and 
NHVdil at existing sources was included in the March 2024 
final rule subpart OOOOc model rule in error. The EPA did not conduct 
Refinery MACT cost level monitoring for existing sources, and stated in 
the preamble to the March 2024 final rule that monitoring of 
NHVcz and NHVdil was not recommended as part of 
the Emission Guidelines for existing sources due to concerns about 
retrofitting existing flares to meet the requirements.\44\ The EPA is 
proposing to correct this inadvertent error by removing the language in 
the model rule to conduct monitoring of NHVcz and 
NHVdil at existing sources and specifying the model rule for 
these control systems is an NHV of 300 Btu/scf in the vent gas. The EPA 
is requesting comment on the appropriateness of using an NHV of 300 
Btu/scf in the vent gas for air- and steam-assisted flares or enclosed 
combustion devices at existing sources for demonstrating compliance 
with the combustion efficiency requirements for these control devices.
---------------------------------------------------------------------------

    \44\ See 89 FR 16895 and 16967.
---------------------------------------------------------------------------

e. Miscellaneous Other Changes
    In addition to the proposed changes described above, the EPA is 
proposing to clarify that for the purposes of determining the hourly 
average of the NHV for continuously sampled (i.e., sampled continuously 
for 14 consecutive days) inlet streams, the hourly average shall be 
determined on a block (and not a rolling) average. The

[[Page 3750]]

EPA is proposing this clarifying edit to ensure that all owners and 
operators are using the same averaging timeframe and it is not left up 
to interpretation as to whether the average should be a block average 
or a rolling average. Block averages are required for other averaging 
time periods in the March 2024 final rule and we consider this change 
to be warranted for consistency and clarity. The EPA also is proposing 
to clarify that the 14-day period for the continuous monitoring option 
shall be consecutive operating days. However, for manual grab sampling, 
the EPA is proposing to allow for breaks for weekends and holidays 
which may occur during the 14-day representative grab sampling period, 
such that these do not have to be consecutive. Consecutive operating 
days are reasonable for continuous monitoring because these systems are 
present continuously. However, manual grab sample collection requires 
someone to be present at the site to collect samples each day, which, 
if required to be done on consecutive days, would require collection on 
weekends and potentially on holidays. The final requirements of the 
March 2024 final rule already allows for sampling beyond the 14 days if 
28 samples cannot be collected during that time frame. Allowing 
additional flexibility for non-consecutive operating day sampling can 
lengthen the time needed to collect samples and delay the conclusion of 
the NHV determination, but it does not reduce the number of samples 
required nor the representativeness of those samples. As such, we 
consider it reasonable to provide some flexibility in the grab sampling 
approach to allow twice daily sampling to determine the average NHV of 
the gas stream for 14 operating days, with no sampling day to be spaced 
more than 3 operating days apart from the previous sampling day. 
Finally, the EPA is proposing to allow 60 days for conducting the 
continuous NHV monitoring required by one of the options in 40 CFR 
60.5417b(d)(8)(ii)(A) through (D) if the results of the periodic (3 
samples every 5 years) sampling indicate that the NHV is less than 1.2 
times the applicable threshold NHV level in the rule. The EPA considers 
it necessary to specify a timeframe to install and operate the required 
continuous monitors to provide owners and operators with regulatory 
certainty for when this must occur. We consider 60 days to be an 
expedited time schedule for the installation of continuous monitoring 
systems, but we consider it a reasonable timeframe for installing 
necessary grab sampling systems to automatically collect samples at 
least once every 8 hours as provided in 40 CFR 60.5417b(d)(8)(ii)(D). 
Facilities would be required to collect grab samples every 8 hours 
until such time a continuous monitor can be installed, and installation 
of such a system requires more than 60 days. We request comment on the 
proposed 60-day compliance provision when a 5-year sampling event 
indicates the vent stream is not sufficiently above the required NHV.
    The EPA also is proposing a similar change to address compliance 
timing pending the re-evaluation that must occur after a process change 
that potentially reduces the NHV of the gas sent to an enclosed 
combustion device or flare. For the same reasons as stated above (i.e., 
for continuous monitoring which must occur after the results of 
periodic monitoring indicate the vent stream is not sufficiently above 
the required NHV), the EPA is proposing that continuous monitoring 
should commence within 60 days after the re-evaluation indicates that 
the inlet gas stream does not meet the limits. The EPA also is 
proposing to clarify, for both periodic testing and re-evaluations 
which occur after a process change, that if the results of the grab 
sampling indicate that the vent stream is not sufficiently above the 
required NHV, continuous monitoring using a calorimeter, GC, MS, or 
continuous grab sampling (i.e., once every 8 hours) sampling must 
commence within the specified timeframe.
    Finally, the EPA is proposing revisions to the provisions in 40 CFR 
60.1547b(d)(8)(v), which include one-time assessments to be used in 
lieu of installing vent gas flow monitors and, in the case of assisted 
flares, assist gas flow monitors if certain provisions are met. While 
we finalized provisions to unassisted flares to conduct an initial 
determination to ensure the flare tip velocity is not exceeded under 
worst-case flow provisions, this requirement was not included in the 
March 2024 final rule for air-assisted flares, even though the velocity 
limits apply. Therefore, we are proposing to add this maximum velocity 
assessment to the existing provisions in 40 CFR 60.1547b(d)(8)(v)(D) 
and (E) for air-assisted flares. This provision is not applicable to 
enclosed combustion devices. In reviewing these provisions, we also 
noted that there was no corresponding provision for steam-assisted 
flares or enclosed combustion devices. This was an oversight in the 
March 2024 final rule and we are proposing new provisions at 40 CFR 
60.1547b(d)(8)(v)(F) similar to those for air-assisted devices that are 
specific to steam-assisted flares or enclosed combustion devices. These 
revisions are not needed in NSPS subpart OOOOc because these provisions 
are specific to evaluations for flares complying with an 
NHVcz or NHVdil parameter. The EPA requests 
comment on these proposed provisions to ensure compliance with the 
velocity operating limit and whether, for those devices that have 
conducted NHV demonstrations, the velocity limit used in the assessment 
should be based on the allowable velocity at the lowest NHV result from 
the demonstration rather than being based on the default of 18.3 
meters/second (60 feet/second).

IV. How do these proposed amendments impact the implementation of EG 
OOOOc?

    The EPA's proposed amendments discussed in section III (Summary and 
Rationale of Proposed Amendments to NSPS OOOOb and EG OOOOc) of this 
preamble in response to several petitions for reconsideration of 
aspects of the 2024 NSPS and EG final rule would not significantly 
impact the implementation of EG OOOOc or the State planning process. 
Based on the EPA's reconsideration, the EPA is proposing amendments 
that revise two narrow aspects of the EG's model rule: (1) The 
associated gas temporary flaring provisions for certain situations and 
(2) the NHV value continuous monitoring and alternative performance 
test (sampling demonstration) provisions for certain combustion control 
devices. The proposed amendments do not alter in any way the EPA's 
identified best system of emission reduction (BSER) in the EG, the 
EPA's identified degree of emissions limitation achievable via 
application of that BSER, the timeline for State plan submittal, or 
compliance timelines finalized under EG OOOOc. Any changes that a State 
or Tribe may make to their plan as a result of this proposed action 
will be minor such that the State or Tribe should be able to make such 
changes before their plans are required to be submitted for approval.
    As indicated in section I.A (Does this action apply to me?) of this 
preamble, the issuance of the CAA section 111(d) final EG does not 
impose binding requirements directly on existing sources. The EG 
(codified in 40 CFR part 60, subpart OOOOc) applies to States in the 
development, submittal, and implementation of State plans to establish 
performance standards to reduce emissions of GHGs from designated 
facilities that are existing sources on or before December 6, 2022. 
Further, under the TAR, eligible Tribes

[[Page 3751]]

may seek approval to implement a plan under CAA section 111(d) in a 
manner similar to a State, and Tribes are authorized under the TAR to 
develop and implement their own air quality programs, or portions 
thereof, under the CAA.

V. Summary of Cost, Environmental, and Economic Impacts

    The proposed NSPS OOOOb and EG OOOOc discrete compliance 
requirement revisions included in this action and discussed in section 
III (Summary and Rationale of Proposed Amendments to NSPS OOOOb and EG 
OOOOc) of this preamble do not alter the substantive requirements of 
the final rule. The economic impacts and a qualitative discussion of 
the environmental impacts are presented in the memorandum titled 
Economic Impact Analysis for 2024 NSPS & EG Reconsideration. There are 
no other quantifiable environmental (e.g., air quality, water, waste), 
energy, or benefits beyond those already presented in accompanying 
Regulatory Impact Analysis (RIA) for the March 8, 2024, Standards of 
Performance for New, Reconstructed, and Modified Sources and Emissions 
Guidelines for Existing Sources: Oil and Natural Gas Sector Climate 
Review final rule (89 FR 16820). As such, a new environmental justice 
(EJ) analysis was not conducted for this action.

VI. Statutory and Executive Order Reviews

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

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

    This action is a ``significant regulatory action'' as defined in 
Executive Order 12866, as amended by Executive Order 14094. 
Accordingly, the EPA submitted this action to the Office of Management 
and Budget (OMB) for Executive Order 12866 review. Documentation of any 
changes made in response to the Executive Order 12866 review is 
available in the docket for this action (see memorandum titled Economic 
Impact Analysis for 2024 NSPS & EG Reconsideration).

B. Paperwork Reduction Act (PRA)

    The information collection activities for NSPS OOOOb and EG OOOOc 
were previously approved by OMB under the PRA as of June 28, 2024.
    The EPA has revised the approved information collection request 
(ICR) to include small changes to incorporate EPA's proposed 
recordkeeping and reporting to indicate whether the flare or enclosed 
combustion device receives inert gases or other streams which may lower 
the NHV of the combined stream as proposed in section III.B of this 
preamble. The EPA estimates an average of 48 respondents will be 
affected by this proposed requirement over the three-year period (2023-
2025). The average annual burden for the recordkeeping and reporting 
requirements for these owners and operators is estimated at 83 person-
hours, with an average annual cost of $4,374 over the three-year 
period.
    The EPA also revised the approved ICR to include burden estimates 
for the maintenance of records that EPA is soliciting comment on. 
Specifically, the EPA includes burden estimates in the revised ICR for 
the records and annual reporting that would be required if EPA were to 
allow for the use of the associated gas extended flaring allowance 
under ``exigent circumstances'' as specified in section III.A of this 
preamble. The incremental increase in burden that would be associated 
with these recordkeeping and reporting requirements relative to the 
baseline is estimated at 2 hours per event annually over the three-year 
period (2024-2026) at an average annual cost of $120 per flaring event 
over the three-year period. The occurrence of flaring that could 
potentially be claimed due to ``exigent circumstances'' is unknown. 
However, we expect that a maximum of 16 percent of flaring events could 
potentially require an owner or operator to need to extend flaring 
beyond 48 hours due to ``exigent circumstances''. The burden associated 
with the two proposed reconsideration items under this action minimally 
affect the ICR burden estimated for compliance with EG OOOOc. The 
annual burden for this proposed additional collection of information 
for the States would be less than 1 percent.
    The approved ICR document that the EPA prepared was assigned OMB 
Control No. 2060-0721 and EPA ICR No. 2523.07. You can find a copy of 
the previously submitted ICR in Docket EPA-HQ-OAR-2021-0317. The 
revised ICR document that the EPA prepared for this reconsideration 
proposal has been assigned OMB Control No. 2060-0721 and EPA ICR No. 
2523.08. You can find a copy of the revised ICR in Docket EPA-HQ-OAR-
2024-0358.

C. Regulatory Flexibility Act (RFA)

    I certify that this action will not have a significant economic 
impact on a substantial number of small entities under the RFA. In 
making this determination, the EPA concludes that the impact of concern 
for this rule is any significant adverse economic impact on small 
entities and that the Agency is certifying that this rule will not have 
a significant economic impact on a substantial number of small entities 
because the rule has reduced net regulatory burden on the small 
entities subject to the rule. This action addresses two discrete 
compliance requirement aspects of NSPS OOOOb and the model rules within 
EG OOOOc based on petitions for reconsideration received on the March 
2024 final rule requirements, providing additional flexibilities to 
entities subject to the NSPS requirements and to the model rules within 
EG OOOOc. We have therefore concluded that this action will have 
reduced net regulatory burden for all directly regulated small 
entities. For further details, see the document, Economic Impact 
Analysis for 2024 NSPS & EG Reconsideration, in the docket.

D. Unfunded Mandates Reform Act (UMRA)

    This action does not contain an unfunded mandate of $100 million or 
more as described in UMRA, 2 U.S.C. 1531-1538, and does not 
significantly or uniquely affect small governments. This action imposes 
no enforceable duty on any State, local or Tribal governments or the 
private sector. This action addresses two discrete compliance 
requirement aspects of NSPS OOOOb and the model rules within EG OOOOc 
based on petitions for reconsideration received on the March 2024 final 
rule requirements.

E. Executive Order 13132: Federalism

    This action does not have federalism implications. It will not have 
substantial direct effects on the States, on the relationship between 
the national government and the States, or on the distribution of power 
and responsibilities among the various levels of government. However, 
the EPA recognizes that States will have a substantial interest in this 
action and any future revisions to associated requirements. This action 
addresses two discrete compliance requirement aspects of NSPS OOOOb and 
the model rules within EG OOOOc based on petitions for reconsideration 
received on the March 2024 final rule requirements.

[[Page 3752]]

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

    This action does not have Tribal implications as specified in 
Executive Order 13175. This action addresses two discrete compliance 
requirement aspects of NSPS OOOOb and the model rules within EG OOOOc 
based on petitions for reconsideration received on the March 2024 final 
rule requirements. Thus, Executive Order 13175 does not apply to this 
action.

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

    The EPA interprets Executive Order 13045 as applying only to those 
regulatory actions that concern environmental health or safety risks 
that the EPA has reason to believe may disproportionately affect 
children, per the definition of ``covered regulatory action'' in 
section 2-202 of the Executive Order. The EPA believes that it is not 
practicable to assess whether an environmental health risk or safety 
risk affecting children may exist prior to this action. This action 
addresses two discrete compliance requirement aspects of NSPS OOOOb and 
the model rules within EG OOOOc based on petitions for reconsideration 
received on the March 2024 final rule requirements and does not result 
in any changes to the BSER of NSPS OOOOb or EG OOOOc. The EPA believes 
that the EPA's Policy on Children's Health also does not apply.

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

    This action is not a ``significant energy action'' because it is 
not likely to have a significant adverse effect on the supply, 
distribution or use of energy. Further, we have concluded that this 
action is not likely to have any adverse energy effects because this 
action addresses two discrete compliance requirement aspects of NSPS 
OOOOb and the model rules within EG OOOOc based on petitions for 
reconsideration received on the March 2024 final rule requirements and 
does not result in any changes to the BSER of NSPS OOOOb or EG OOOOc.

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

    This action does not involve any new technical standards. 
Therefore, the NTTAA does not apply.

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

    The EPA believes that it is not practicable to assess whether the 
human health or environmental conditions that exist prior to this 
action result in disproportionate and adverse effects on communities 
with EJ concerns. This action addresses two discrete compliance 
requirement aspects of NSPS OOOOb and the model rules within EG OOOOc 
based on petitions for reconsideration received on the March 2024 final 
rule requirements and does not result in any changes to the BSER of 
NSPS OOOOb or EG OOOOc. The EPA lacks specific and representative data 
on the frequency of temporary or emergency flaring, the number of 
sources flaring, or the length of time temporary flaring occurs. This 
data limitation prevents the EPA from estimating the impacts of an 
extension of allowed flaring. The March 2024 final rule describes how 
the rule will result in reductions in VOCs, which are an important 
precursor contributing to ground-level ozone formation in many regions 
of the country and reduce methane pollution that contributes to climate 
change, which itself has substantial and adverse impacts on EJ 
communities.\45\ The information supporting this Executive Order review 
is contained in the docket for this action (see memorandum titled 
Economic Impact Analysis for 2024 NSPS & EG Reconsideration).
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    \45\ 89 FR 17031.

Michael S. Regan,
Administrator.
[FR Doc. 2024-31227 Filed 1-14-25; 8:45 am]
BILLING CODE 6560-50-P
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