[Federal Register Volume 85, Number 178 (Monday, September 14, 2020)]
[Rules and Regulations]
[Pages 57018-57072]
[FR Doc No: 2020-18114]

Vol. 85

Monday,

No. 178

September 14, 2020

Part IV

 Environmental Protection Agency

-----------------------------------------------------------------------

40 CFR Part 60

Oil and Natural Gas Sector: Emission Standards for New, Reconstructed,
and Modified Sources Review; Final Rule

Federal Register / Vol. 85, No. 178 / Monday, September 14, 2020 /
Rules and Regulations

-----------------------------------------------------------------------

ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 60

[EPA-HQ-OAR-2017-0757; FRL-10013-44-OAR]
RIN 2060-AT90

Oil and Natural Gas Sector: Emission Standards for New,
Reconstructed, and Modified Sources Review

AGENCY: Environmental Protection Agency (EPA).

ACTION: Final rule.

-----------------------------------------------------------------------

SUMMARY: This action finalizes amendments to the oil and natural gas
new source performance standards (NSPS) promulgated in 2012 and 2016.
These amendments remove sources in the transmission and storage segment
from the source category, rescind the NSPS (including both the volatile
organic compounds (VOC) and methane requirements) applicable to those
sources, and separately rescinds the methane-specific requirements of
the NSPS applicable to sources in the production and processing
segments. Furthermore, the U.S. Environmental Protection Agency (EPA)
adopts an interpretation of Clean Air Act (CAA) section 111 under which
the EPA, as a predicate to promulgating NSPS for certain air
pollutants, must determine that the pertinent pollutant causes or
contributes significantly to dangerous air pollution.

DATES: This final rule is effective on September 14, 2020.

ADDRESSES: The EPA established a docket for this action under Docket ID
No. EPA-HQ-OAR-2017-0757. All documents in the docket are listed on the
https://www.regulations.gov/ website. Although listed, some information
is not publicly available, e.g., Confidential Business Information or
other information whose disclosure is restricted by statute. Certain
other material, such as copyrighted material, is not placed on the
internet and will be publicly available only in hard copy form.
Publicly available docket materials are available electronically
through https://www.regulations.gov/. Out of an abundance of caution
for members of the public and our staff, the EPA Docket Center and
Reading Room are closed to the public, with limited exceptions, to
reduce the risk of transmitting COVID-19. Our Docket Center staff will
continue to provide remote customer service via email, phone, and
webform. For further information and updates on EPA Docket Center
services, please visit us online at https://www.epa.gov/dockets. The
EPA continues to carefully and continuously monitor information from
the Center for Disease Control, local area health departments, and our
Federal partners so that we can respond rapidly as conditions change
regarding COVID-19.

FOR FURTHER INFORMATION CONTACT: For questions about this final action,
contact Ms. Amy Hambrick, Sector Policies and Programs Division (E143-
05), Office of Air Quality Planning and Standards, U.S. Environmental
Protection Agency, Research Triangle Park, North Carolina 27711;
telephone number:<PHONE_NUMBER>; fax number:<PHONE_NUMBER>; and email
address<EMAIL_ADDRESS>
SUPPLEMENTARY INFORMATION: Preamble acronyms and abbreviations. We use
multiple acronyms and terms in this preamble. While this list may not
be exhaustive, to ease the reading of this preamble and for reference
purposes, the EPA defines the following terms and acronyms here:

AEO Annual Energy Outlook
APA Administrative Procedure Act
BSER best system of emission reduction
CAA Clean Air Act
CFR Code of Federal Regulations
CH4 methane
CO carbon monoxide
CO2 carbon dioxide
CO2 Eq. carbon dioxide equivalent
EAV equivalent annualized value
EG Emission Guidelines
EGU Electricity Generating Units
EIA U.S. Energy Information Administration
EPA Environmental Protection Agency
GHG greenhouse gases
GHGI greenhouse gas inventory
GHGRP Greenhouse Gas Reporting Program
HAP hazardous air pollutant(s)
H2S hydrogen sulfide
ICR Information Collection Request
IR infrared
kt kilotons
MMT million metric tons
NAAQS National Ambient Air Quality Standards
NAICS North American Industry Classification System
NEI National Emissions Inventory
NEMS National Energy Modeling System
NOX nitrogen oxides
NSPS new source performance standards
NTTAA National Technology Transfer and Advancement Act
OGI optical gas imaging
OMB Office of Management and Budget
PM particulate matter
PM2.5 PM with a diameter of 2.5 micrometers or less
PM10 PM with a diameter of 10 micrometers or less
PRA Paperwork Reduction Act
PV present value
RFA Regulatory Flexibility Act
RIA Regulatory Impact Analysis
SC-CH4 social cost of methane
SCF significant contribution finding
scfh standard cubic feet per hour
SIP state implementation plan
SO2 sulfur dioxide
tpy tons per year
the Court United States Court of Appeals for the District of
Columbia Circuit
TSD technical support document
UMRA Unfunded Mandates Reform Act
U.S. United States
VOC volatile organic compounds

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

I. Executive Summary
    A. Purpose and Summary of the Regulatory Action
    B. Costs and Benefits
II. General Information
    A. Does this action apply to me?
    B. How do I obtain a copy of this document, background
information, other related information?
    C. Judicial Review
III. Background
IV. 2019 Proposal
V. Final Action and Rationale
    A. Summary of Final Action
    B. Rationale
VI. Significant Contribution
    A. Legal Interpretation Concerning the Air Pollutants That Are
Subject to CAA Section 111
    B. Flaws in the 2016 Rule's Significant Contribution Finding
    C. Criteria for Making a Significant Contribution Finding Under
CAA Section 111
VII. Implications for Regulation of Existing Sources
    A. Existing Source Regulation Under CAA Section 111(d)
    B. Impact of Lack of Regulation of Existing Oil and Natural Gas
Sources Under CAA Section 111(d)
VIII. Summary of Major Comments and Responses
    A. Revision of the Source Category To Remove Transmission and
Storage Segment
    B. Rescission of the Applicability to Methane of the NSPS for
Production and Processing Segments
IX. Summary of Significant Comments and Responses on Significant
Contribution Finding for Methane
    A. Requirement for Pollutant-Specific Significant Contribution
Finding
    B. Significant Contribution Finding in 2016 Rule
    C. Criteria for Making a Significant Contribution Finding Under
CAA Section 111
X. Summary of Significant Comments and Responses Concerning
Implications for Regulation of Existing Sources
    A. Existing Source Regulation Under CAA Section 111(d)
    B. Limited Impact of Lack of Regulation of Existing Oil and
Natural Gas Sources Under CAA Section 111(d)
XI. Impacts of This Final Rule
    A. What are the air impacts?
    B. What are the energy impacts?
    C. What are the compliance costs?
    D. What are the economic and employment impacts?

    E. What are the benefits of the final standards?
XII. Statutory and Executive Order Reviews
    A. Executive Order 12866: Regulatory Planning and Review and
Executive Order 13563: Improving Regulation and Regulatory Review
    B. Executive Order 13771: Reducing Regulations and Controlling
Regulatory Costs
    C. Paperwork Reduction Act (PRA)
    D. Regulatory Flexibility Act (RFA)
    E. Unfunded Mandates Reform Act (UMRA)
    F. Executive Order 13132: Federalism
    G. Executive Order 13175: Consultation and Coordination With
Indian Tribal Governments
    H. Executive Order 13045: Protection of Children From
Environmental Health Risks and Safety Risks
    I. Executive Order 13211: Actions Concerning Regulations That
Significantly Affect Energy Supply, Distribution, or Use
    J. National Technology Transfer and Advancement Act (NTTAA)
    K. Executive Order 12898: Federal Actions To Address
Environmental Justice in Minority Populations and Low-Income
Populations
    L. Congressional Review Act (CRA)

I. Executive Summary

A. Purpose and Summary of the Regulatory Action

    The EPA is finalizing amendments to its 2012 and 2016 Rules
affecting the oil and natural gas industry, titled, respectively, ``Oil
and Natural Gas Sector: New Source Performance Standards and National
Emission Standards for Hazardous Air Pollutants Reviews; Final Rule''
(``2012 Rule'') \1\ and ``Oil and Natural Gas Sector: Emission
Standards for New, Reconstructed, and Modified Sources; Final Rule''
(``2016 Rule'').\2\ Those rules established NSPS for VOC emissions from
the oil and natural gas industry, and the 2016 Rule also established
NSPS for greenhouse gases (GHG), in the form of limitations on methane,
for that industry.\3\ The amendments that the EPA is finalizing are
intended to continue existing protections from emission sources within
the source category that the EPA originally listed for regulation under
CAA section 111--termed the Oil and Natural Gas Production Source
Category--while removing regulatory duplication.
---------------------------------------------------------------------------

    \1\ 77 FR 49490 (August 16, 2012).
    \2\ 81 FR 35824 (June 3, 2016).
    \3\ Docket ID No. EPA-HQ-OAR-2010-0505.
---------------------------------------------------------------------------

    In response to President Donald J. Trump's March 2017 Executive
Order on Promoting Energy Independence and Economic Growth, the EPA has
reviewed the 2012 and 2016 Rules with attention to whether they
``unduly burden the development of domestic energy resources beyond the
degree necessary to protect the public interest or otherwise comply
with the law'' and, thus, should be ``suspend[ed], revise[d], or
rescind[ed]''.4 5 From this review, the EPA has determined
that some of the requirements under those rules are inappropriate. For
example, some of these requirements affect sources that are not
appropriately identified as part of the regulated source category. In
addition, some of the requirements under the 2016 Rule are unnecessary
insofar as they impose redundant requirements. Accordingly, the EPA is
acting to rescind those requirements while maintaining health and
environmental protections from appropriately identified emission
sources within the regulated source category.\6\
---------------------------------------------------------------------------

    \4\ Executive Order 13783, ``Promoting Energy Independence and
Economic Growth,'' section 1(c) (March 28, 2017); see also section
7(a) (specifically directing the EPA to review the 2016 Rule, ``and
any rules and guidance issued pursuant to it, for consistency with
the policy set forth in section 1 of this order and, if appropriate,
[to], as soon as practicable, suspend, revise, or rescind the
guidance, or publish for notice and comment proposed rules
suspending, revising, or rescinding those rules'').
    \5\ 82 FR 16331 (April 4, 2017) (review of 2016 Rule pursuant to
Executive Order 13783, signed by the EPA Administrator).
    \6\ We note that the EPA is addressing certain specific
reconsideration issues--fugitive emissions requirements at well
sites and compressor stations, well site pneumatic pump standards,
and the requirements for certification of closed vent systems by a
professional engineer (PE)--in a separate final rule. See Docket ID
Item No. EPA-HQ-OAR-2010-0505-7730 and 82 FR 25730.
---------------------------------------------------------------------------

    Specifically, the EPA is finalizing what it referred to as the
primary proposal in the September 24, 2019, proposed action (``2019
Proposal''). Thus, this final rule contains two main actions. First,
the EPA is finalizing a determination that the source category includes
only the production and processing segments of the industry and is
rescinding the standards applicable to the transmission and storage
segment of the industry. This determination is based on the EPA's
review of the original source category listing and its 2012 and 2016
Rules' interpretations of, and its 2016 Rule's revision to, the scope
of the source category, which, as revised, covered sources in the
transmission and storage segment. Having reexamined its prior
rulemakings regarding the scope of this source category and the
transmission and storage segment, the EPA has determined that the
revision in the 2016 Rule of the original source category was not
appropriate. Because the EPA is determining that the original source
category did not cover the transmission and storage segment, and that
this segment constitutes a separate source category from the production
and processing segments, the EPA was authorized to list it for
regulation under CAA section 111(b) only by making a cause-or-
contribute-significantly and endangerment finding as required by the
statute, which the EPA never did. Accordingly, in this first action,
the EPA is rescinding the standards applicable to sources in the
transmission and storage segment of the oil and natural gas industry.
    Second, the EPA is separately rescinding the methane requirements
of the NSPS applicable to sources in the production and processing
segments. The EPA is concluding that those methane requirements are
redundant with the existing NSPS for VOC and, thus, establish no
additional health protections. The emission source control technologies
that apply to the sources achieve reductions in both methane and VOC
emissions, and the recordkeeping and other requirements overlap as
well. Rescinding the applicability of the 2016 Rule requirements to
methane emissions, while leaving the applicability to VOC emissions in
place, will not affect the amount of methane emission reductions that
those requirements will achieve.
    This final rule also concludes that, as a prerequisite for newly
regulating any air pollutant that the EPA did not consider when listing
or initially regulating the source category, CAA section 111 requires
the EPA to make a finding that emissions of that air pollutant from the
source category cause or contribute significantly (which we term the
significant contribution finding, or SCF) to air pollution which may
reasonably be anticipated to endanger public health or welfare (which
we sometimes refer to as dangerous air pollution). Further, the final
rule determines that the SCF for methane that the EPA made in the
alternative in the 2016 Rule was invalid and did not meet this
statutory standard, for two reasons: (i) The EPA made that finding on
the basis of methane emissions from the production, processing, and
transmission and storage segments, instead of just the production and
processing segments; and (ii) the EPA failed to support that finding
with either established criteria or some type of reasonably explained
and intelligible standard or threshold for determining when an air
pollutant contributes significantly to dangerous air pollution. The
fact that the 2016 Rule's SCF for methane was invalid provides another
basis for rescinding the methane requirements for the

production and processing segments. While the EPA took comment in the
2019 Proposal on what criteria should inform its judgment as to whether
a pollutant causes or contributes significantly to dangerous air
pollution, the EPA is not taking further action on such criteria in
this rulemaking.

B. Costs and Benefits

    The EPA has projected the compliance cost reductions, emissions
changes, and forgone benefits that may result from the final rule for
the years of analysis, 2021 to 2030. The projected cost reductions and
forgone benefits are presented in detail in the Regulatory Impact
Analysis (RIA) accompanying this final rule. The EPA notes that the
projected cost reductions and forgone benefits are directly associated
with the rescission of the NSPS applicable to sources in the
transmission and storage segment of the source category and not the
rescission of methane from the production and processing segments.
    A summary of the key results of this final rule is presented in
Table 1.\7\ Table 1 presents the present value (PV) and equivalent
annualized value (EAV), estimated using discount rates of 7 and 3
percent, of the changes in benefits, costs, and net benefits, as well
as the change in emissions under the final rule. Here, the EPA refers
to the cost reductions as the ``benefits'' of this rule and the forgone
benefits as the ``costs'' of this rule in Table 1. The net benefits are
the benefits (cost reductions) minus the costs (forgone benefits).
---------------------------------------------------------------------------

    \7\ In a separate action, the EPA is finalizing technical
reconsideration amendments to 40 CFR part 60, subpart OOOOa (EPA-HQ-
OAR-2017-0483; FRL-10013-60-OAR; FR Doc. 2020-18115). These
technical amendments where proposed in October 2018. 83 FR 52056.
Please reference that final rule for the summary and rationale of
those technical changes. Please refer to the RIA for both rules to
see the combined impacts.

  Table 1--Cost Reductions, Forgone Benefits, and Forgone Emissions Reductions of the Final Rule, 2021 Through
                                                      2030
                                                [Millions 2016$]
----------------------------------------------------------------------------------------------------------------
                                                      7-Percent discount rate         3-Percent discount rate
                                                 ---------------------------------------------------------------
                                                        PV              EAV             PV              EAV
----------------------------------------------------------------------------------------------------------------
Benefits (Total Cost Reductions)................             $31            $4.1             $38            $4.3
Costs (Forgone Benefits)........................              17             2.2              63             7.2
Net Benefits 1..................................              14             1.9             -25            -2.9
                                                 ---------------------------------------------------------------
Emissions.......................................                        Forgone Reductions
Methane (short tons)............................                              400,000
VOC (short tons)................................                              11,000
Hazardous Air Pollutant(s) (HAP) (short tons)...                                330
Methane (million metric tons carbon dioxide
 equivalent (CO2 Eq.))..........................                                 9
----------------------------------------------------------------------------------------------------------------
1 Note: Estimates may not sum due to independent rounding.

    This final rule is expected to result in benefits (compliance cost
reductions) for affected owners and operators. The PV of these benefits
(cost reductions), discounted at a 7-percent rate, is estimated to be
about $31 million, with an EAV of about $4.1 million (Table 1). Under a
3-percent discount rate, the PV of cost reductions is $38 million, with
an EAV of $4.3 million (Table 1).
    The estimated costs (forgone benefits) include the monetized
climate effects of the projected increase in methane emissions under
the final rule. The PV of these climate-related costs (forgone
benefits), discounted at a 7-percent rate, is estimated to be about $17
million, with an EAV of about $2.2 million (Table 1). Under a 3-percent
discount rate, the PV of the climate-related costs (forgone benefits)
is about $63 million, with an EAV of about $7.2 million (Table 1). The
EPA also expects that there will be increases in VOC and HAP emissions
as a result of this final rule. While the EPA expects that the forgone
VOC emission reductions may also degrade air quality and adversely
affect health and welfare effects associated with exposure to ozone,
particulate matter with a diameter of 2.5 micrometers or less
(PM2.5), and HAP, we are unable to quantify these effects at
this time. This omission should not imply that these forgone benefits
do not exist. To the extent that the EPA were to quantify these ozone
and particulate matter (PM) impacts, the Agency would estimate the
number and value of avoided premature deaths and illnesses using an
approach detailed in the Particulate Matter National Ambient Air
Quality Standards (NAAQS) and Ozone NAAQS RIA (U.S. EPA, 2012; U.S.
EPA, 2015).
    The PV of the net benefits of this rule, discounted at a 7-percent
rate, is estimated to be about $14 million, with an EAV of about $1.9
million (Table 1). Under a 3-percent discount rate, the PV of net
benefits is about $-25 million, with an EAV of about $-2.9 million
(Table 1).

II. General Information

A. Does this action apply to me?

    Categories and entities potentially affected by this action
include:

      Table 2--Industrial Source Categories Affected by This Action
------------------------------------------------------------------------
                                  NAICS code 1    Examples of regulated
            Category                                     entities
------------------------------------------------------------------------
Industry.......................          211120  Crude Petroleum
                                                  Extraction.
                                         211130  Natural Gas Extraction.
                                         221210  Natural Gas
                                                  Distribution.
                                         486110  Pipeline Distribution
                                                  of Crude Oil.
                                         486210  Pipeline Transportation
                                                  of Natural Gas.
Federal Government.............  ..............  Not affected.

State/local/tribal government..  ..............  Not affected.
------------------------------------------------------------------------
1 North American Industry Classification System (NAICS).

    This table is not intended to be exhaustive, but rather provides a
guide for readers regarding entities likely to be affected by this
action. Other types of entities not listed in the table could also be
affected by this action. To determine whether your entity is affected
by this action, you should carefully examine the applicability criteria
found in the final rule. If you have questions regarding the
applicability of this action to a particular entity, consult the person
listed in the FOR FURTHER INFORMATION CONTACT section, your air
permitting authority, or your EPA Regional representative listed in 40
CFR 60.4 (General Provisions).

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

    In addition to being available in the docket, an electronic copy of
the final action is available on the internet. Following signature by
the Administrator, the EPA will post a copy of this final action at
https://www.epa.gov/controlling-air-pollution-oil-and-natural-gas-industry. Following publication in the Federal Register, the EPA will
post the Federal Register version of the final rule and key technical
documents at this same website. A redline version of the regulatory
language that incorporates the final changes in this action is
available in the docket for this action (Docket ID No. EPA-HQ-OAR-2017-
0757). Additional background information about this final rule,
including industry and emissions information, regulatory history,
litigation background, other notable events, related Federal actions,
and a comprehensive summary and rationale of the proposed options can
be found at 84 FR 50244 (September 24, 2019).

C. Judicial Review

    Under section 307(b)(1) of the CAA, judicial review of this final
rule is available only by filing a petition for review in the United
States Court of Appeals for the District of Columbia Circuit (``the
Court'') by November 13, 2020. Moreover, under section 307(b)(2) of the
CAA, the requirements established by this final rule may not be
challenged separately in any civil or criminal proceedings brought by
the EPA to enforce these requirements. Section 307(d)(7)(B) of the CAA
further provides that ``[o]nly an objection to a rule or procedure
which was raised with reasonable specificity during the period for
public comment (including any public hearing) may be raised during
judicial review.'' This section also provides a mechanism for the EPA
to convene a proceeding for reconsideration, ``[i]f the person raising
an objection can demonstrate to the EPA that it was impracticable to
raise such objection within [the period for public comment] or if the
grounds for such objection arose after the period for public comment
(but within the time specified for judicial review) and if such
objection is of central relevance to the outcome of the rule.'' Any
person seeking to make such a demonstration to us should submit a
Petition for Reconsideration to the Office of the Administrator, U.S.
Environmental Protection Agency, Room 3000, WJC South Building, 1200
Pennsylvania Ave. NW, Washington, DC 20460, with a copy to both the
person(s) listed in the preceding FOR FURTHER INFORMATION CONTACT
section, and the Associate General Counsel for the Air and Radiation
Law Office, Office of General Counsel (Mail Code 2344A), U.S.
Environmental Protection Agency, 1200 Pennsylvania Ave. NW, Washington,
DC 20460.

III. Background

    The EPA reviewed the relevant background in the 2019 Proposal,
including discussing the oil and natural gas industry and its
emissions, 84 FR 50247 through 50; the statutory background, Id. at
50251; the regulatory history and litigation background regarding
performance standards for the oil and natural gas industry, Id. at
50251 and 52; other notable events, including the March 28, 2017,
Executive Order that led the EPA to initiate this rulemaking, Id. at
50252 and 53; and related state and Federal regulatory actions, Id. at
50253 and 54. The EPA incorporates that information by reference and
will not repeat it here.
    Since the 2019 Proposal, the EPA has updated information on the oil
and natural gas industry emissions inventories based on the recently
released Inventory of United States Greenhouse Gas Emissions and Sinks:
1990-2018 (published April 13, 2020) and the 2017 National Emissions
Inventory (NEI) (released February 2020). In Tables 3 to 7 below, the
EPA provides the updated estimate of emissions of methane, VOC, and
sulfur dioxide (SO2) from oil and natural gas industry
sources.
    Methane emissions in the U.S. and from the oil and natural gas
industry. Official U.S. estimates of national level GHG emissions and
sinks are developed by the EPA for the U.S. GHG Inventory (GHGI) to
comply with commitments under the United Nations Framework Convention
on Climate Change. The U.S. GHGI, which includes recent trends, is
organized by industrial sectors. The oil and natural gas production,
natural gas processing, and natural gas transmission and storage
sectors emit 25 percent of U.S. anthropogenic methane. Table 3 below
presents total U.S. anthropogenic methane emissions for the years 1990,
2008, and 2018.

                                    Table 3--U.S. Methane Emissions by Sector
                          [Million metric ton carbon dioxide equivalent (MMT CO2 eq.)]
----------------------------------------------------------------------------------------------------------------
                             Sector                                    1990            2008            2018
----------------------------------------------------------------------------------------------------------------
Oil and Natural Gas Production, and Natural Gas Processing and               185             185             163
 Transmission and Storage.......................................
    Oil and Natural Gas Production, and Natural Gas Processing..             128             153             129
    Oil and Natural Gas Transmission and Storage................              57              32              34
Landfills.......................................................             180             125             111

Enteric Fermentation............................................             164             174             178
Coal Mining.....................................................              97              76              53
Manure Management...............................................              37              54              62
Other Oil and Gas Sources.......................................              44              18              13
Wastewater Treatment............................................              15              15              14
Other Methane Sources 8.........................................              57              51              57
                                                                 -----------------------------------------------
    Total Methane Emissions.....................................             779             698             650
----------------------------------------------------------------------------------------------------------------
Emissions from the Inventory of United States Greenhouse Gas Emissions and Sinks: 1990-2018 (published April 13,
  2020), calculated using global warming potential (GWP) of 25. Note: Totals may not sum due to rounding.

    Table 4 below presents total methane emissions from natural gas
production through transmission and storage and petroleum production,
for years 1990, 2008, and 2018, in MMT CO2 Eq. (or million
metric tonnes CO2 Eq.) of methane.
---------------------------------------------------------------------------

    \8\ Other sources include rice cultivation, forest land,
stationary combustion, abandoned oil and natural gas wells,
abandoned coal mines, mobile combustion, composting, and several
sources emitting less than 1 MMT CO2 Eq. in 2018.

                     Table 4--U.S. Methane Emissions From Natural Gas and Petroleum Systems
                                                  [MMT CO2 eq.]
----------------------------------------------------------------------------------------------------------------
                             Sector                                    1990            2008            2018
----------------------------------------------------------------------------------------------------------------
Oil and Natural Gas Production and Natural Gas Processing and                185             185             163
 Transmission (Total)...........................................
Natural Gas Production..........................................              61             100              82
Natural Gas Processing..........................................              21              11              12
Natural Gas Transmission and Storage............................              57              32              34
Petroleum Production............................................              45              42              35
----------------------------------------------------------------------------------------------------------------
Emissions from the Inventory of United States Greenhouse Gas Emissions and Sinks: 1990-2018 (published April 13,
  2020), calculated using GWP of 25. Note: Totals may not sum due to rounding.

    VOC and SO2 emissions in the U.S. and from the oil and natural gas
industry. Official U.S. estimates of national level VOC and
SO2 emissions are developed by the EPA for the NEI, for
which states are required to submit information under 40 CFR part 51,
subpart A. Data in the NEI may be organized by various data points,
including sector, NAICS code, and Source Classification Code. The oil
and natural gas sources emit 5.8 and 2.4 percent of U.S. VOC and
SO2, respectively. Tables 5 and 6 below present total U.S.
VOC and SO2 emissions by sector, respectively, for the year
2017, in kilotons (kt) (or thousand metric tons).

                  Table 5--U.S. VOC Emissions by Sector
                                  [kt]
------------------------------------------------------------------------
                         Sector                                2017
------------------------------------------------------------------------
Biogenics--Vegetation and Soil..........................          25,823
Fires--Wildfires........................................           4,578
Oil and Natural Gas Production, and Natural Gas                    2,504
 Processing and Transmission............................
Fires--Prescribed Fires.................................           2,042
Solvent--Consumer and Commercial Solvent Use............           1,610
Mobile--On-Road non-Diesel Light Duty Vehicles..........           1,507
Mobile--Non-Road Equipment--Gasoline....................           1,009
Other VOC Sources 9.....................................           4,045
                                                         ---------------
    Total VOC Emissions.................................          43,118
------------------------------------------------------------------------
Emissions from the 2017 NEI (released April 2020). Note: Totals may not
  sum due to rounding.

                  Table 6--U.S. SO2 Emissions by Sector
                                  [kt]
------------------------------------------------------------------------
                         Sector                                2017
------------------------------------------------------------------------
Fuel Combustion--Electric Generation--Coal..............           1,319
Fuel Combustion--Industrial Boilers, Internal Combustion             212
 Engines--Coal..........................................
Mobile--Commercial Marine Vessels.......................             183

Industrial Processes--Not Elsewhere Classified..........             138
Fires--Wildfires........................................             135
Industrial Processes--Chemical Manufacturing............             123
Oil and Natural Gas Production and Natural Gas                        65
 Processing and Transmission............................
Other SO2 Sources 10....................................             551
                                                         ---------------
    Total SO2 Emissions.................................           2,726
------------------------------------------------------------------------
Emissions from the 2017 NEI (released April 2020). Note: Totals may not
  sum due to rounding.

    Table 7 below presents total VOC and SO2 emissions from
oil and natural gas production through transmission and storage, for
the year 2017, in kt (or thousand metric tons).
---------------------------------------------------------------------------

    \9\ Other sources include remaining sources emitting less than
1,000 kt VOC in 2017.
    \10\ Other sources include remaining sources emitting less than
100 kt SO2 in 2017.

   Table 7--U.S. VOC and SO2 Emissions From Natural Gas and Petroleum
                                 Systems
                                  [kt]
------------------------------------------------------------------------
                 Sector                         VOC             SO2
------------------------------------------------------------------------
Oil and Natural Gas Production and                 2,504              65
 Natural Gas Processing and Transmission
 (Total)................................
Oil and Natural Gas Production..........           2,478              41
Natural Gas Processing..................              12              23
Natural Gas Transmission and Storage....              14               1
------------------------------------------------------------------------
Emissions from the 2017 NEI, (published April 2020), in kt (or thousand
  metric tons). Note: Totals may not sum due to rounding.

IV. 2019 Proposal

    On September 24, 2019, the EPA issued a proposed rulemaking (2019
Proposal) to amend the 2012 Rule and 2016 Rule for the oil and natural
gas industry that would remove regulatory duplication and save the
industry millions of dollars in compliance costs each year, while
maintaining health and environmental protections from oil and natural
gas sources that the Agency considers appropriate to regulate in this
rule.\11\ The EPA issued the proposal in response to President Trump's
Executive Order on Promoting Energy Independence and Economic Growth.
Generally speaking, that order directs agencies to review existing
regulations that potentially ``burden the development or use of
domestically produced energy resources,'' including oil and natural
gas, and to suspend, revise, or rescind such regulatory requirements if
appropriate. The proposal included a primary regulatory option and an
alternative regulatory option. The primary option proposed to remove
all sources in the transmission and storage segment of the oil and
natural gas industry from regulation under the NSPS, both for VOC and
for GHG. The primary option separately proposed to rescind the methane
requirements in the 2016 Rule that apply to sources in the production
and processing segments of the industry. The alternative option
proposed to rescind the methane requirements that apply to all sources
in the oil and natural gas industry, without removing any sources from
the source category as defined in the 2016 Rule. The EPA additionally
solicited comment on alternative interpretations of the EPA's legal
authority to regulate pollutants under CAA section 111.
---------------------------------------------------------------------------

    \11\ 84 FR 50244.
---------------------------------------------------------------------------

    CAA section 111 requires the EPA to set NSPS for categories of
stationary sources that the EPA has listed (``source categories'')
because they cause, or significantly contribute to, air pollution that
may reasonably be anticipated to endanger public health or welfare. The
Agency's original source category listing for the oil and natural gas
industry, issued in 1979, included only the crude oil and natural gas
production and natural gas processing segments of the industry.
However, in the 2012 Rule and 2016 Rule, the EPA interpreted the 1979
listing to have established the scope of the source category as
including the industry's transmission and storage segment. In the 2016
Rule, the EPA also, as an alternative, expanded the source category to
include the transmission and storage segment. In the 2019 Proposal, the
EPA proposed to remove sources in the transmission and storage segment
from the Oil and Natural Gas Production source category on the grounds
that the Agency had erred in the 2012 and 2016 Rules when it had
interpreted or expanded the source category, because the transmission
and storage segment of the industry is functionally separate from the
production and processing segment. The EPA further stated that a
separate SCF would be necessary for that segment to be listed as a
source category for regulation. The proposal further stated that the
emissions limits that apply to sources in the transmission and storage
segment in the 2012 Rule and 2016 Rule would be rescinded because that
segment would be removed from the source category. Finally, the EPA
proposed to rescind emissions requirements for methane for sources
located in the production and processing segments on grounds that those
requirements are redundant to the requirements for VOC. The proposal
made clear that the emissions limits for VOC would remain for the
production and processing segments.
    In the alternative proposal, the EPA proposed to rescind the
methane requirements in the 2016 Rule for all oil and natural gas
sources, without removing the transmission and storage sources from the
source category. Under this alternative, the rule would retain VOC
standards for the production, processing, and transmission and storage
segments of the industry. As with the primary proposal, the alternative
proposal is based on the view that because the controls to reduce VOC
emissions also reduce methane, separate methane requirements for the
industry are redundant.
    The EPA further stated that the proposed amendments would remove
the Agency's obligation to develop emission guidelines (EG) to address
methane emissions from existing sources under section 111(d) of the
CAA. The EPA stated its belief that not

regulating existing sources would have limited environmental impact,
because some existing sources will ``modify'' such that they will
become subject to requirements for new sources, and because the number
of remaining sources may decline over time as they are shut down or
become obsolete.
    The EPA also took comment on an alternative interpretation of its
legal authority to regulate pollutants under CAA section 111. In the
2016 Rule, the EPA took the position that the law did not require the
Agency, as a prerequisite to regulating methane as part of the NSPS, to
first make a separate determination that GHG emissions from the oil and
natural gas industry cause, or significantly contribute to, dangerous
air pollution (a pollutant-specific SCF). However, the Agency also made
a finding in the alternative that if the CAA were interpreted to
require a pollutant-specific SCF, then GHG emissions from the Oil and
Natural Gas source category do cause or contribute significantly to
dangerous air pollution. The 2019 Proposal solicited comment on three
issues: (1) Whether the Agency should revise the interpretation it took
in the 2016 Rule, so that CAA section 111 requires the EPA to make a
pollutant-specific SCF for GHG emissions from the oil and natural gas
industry as a predicate to regulation; (2) whether, if CAA section 111
does require a pollutant-specific SCF, whether the finding in the
alternative in the 2016 Rule satisfied that requirement; and (3) what,
if any, specific criteria the EPA should use to make a pollutant-
specific SCF.
    The EPA solicited comments on all aspects of the proposal during a
60-day public comment period. The EPA held a public hearing in Dallas,
Texas, in October 2019; 105 speakers provided oral testimony and 32
observers attended. The EPA received almost 300,000 public comments on
the proposed rule. The EPA is not responding to any late comment
received.

V. Final Action and Rationale

A. Summary of Final Action

    The EPA is finalizing what was referred to as the primary proposal
in the 2019 Proposal. First, the final rule removes all sources in the
transmission and storage segment of the oil and natural gas industry
from regulation under the NSPS and removes all emissions limitations
for both VOC and GHG for sources in the transmission and storage
segment. Second, the final rule separately rescinds the standards for
methane emissions in the 2016 Rule that apply to sources in the
production and processing segments of the industry. Third, the final
rule articulates the EPA's interpretation that under CAA section
111(b)(1)(A), as a prerequisite for newly regulating any air pollutant,
the Agency is required to make a finding that emissions of the air
pollutant, from the source category, cause or contribute significantly
to air pollution which may reasonably be anticipated to endanger public
health or welfare. Further, the final rule concludes that the
alternative SCF made by the EPA in the 2016 Rule was invalid and did
not meet this statutory standard.

B. Rationale

1. Revision of the Source Category To Remove Transmission and Storage
Segment
    As noted above, the EPA is finalizing its proposal to remove the
transmission and storage segment entirely from the source category and
rescind the NSPS requirements applicable to sources within that
segment. This final action is based on the EPA's determination that its
2012 and 2016 rulemakings that interpreted or expanded the source
category to include sources in that segment were improper. The
following discussion provides background on CAA section 111, the
history of the Oil and Natural Gas Production source category, and the
rationale for this final decision.
    Under CAA section 111(b)(1)(A), the EPA must ``publish . . . a list
of categories of stationary sources, emissions from which, in the
judgment of the Administrator, cause[ ], or contribute[ ] significantly
to, air pollution which may reasonably be anticipated to endanger
public health or welfare.'' Further, CAA section 111(b)(1)(A) directs
that ``from time to time thereafter'' the EPA ``shall revise'' this
``list'' of categories of stationary sources. Following the ``inclusion
of a category of stationary sources in a list,'' the EPA then proposes
and promulgates ``standards of performance for new sources within such
category.'' CAA Section 111(b)(1)(B). Thereafter, the EPA ``shall . . .
review and, if appropriate, revise such standards.'' Id.
    CAA section 111(b)(1)(A) does not include any specific criteria for
determining the reasonable scope of a given ``category'' of
``stationary sources'' beyond the requirement that the Administrator
make a finding that, in his or her ``judgment,'' emissions from the
``category of sources . . . cause[ ], or contribute[ ]significantly to,
air pollution which may reasonably be anticipated to endanger public
health or welfare.'' Accordingly, the EPA is afforded some measure of
discretion in determining at the outset the scope of a source category.
    In 1978, the EPA published ``Priorities for New Source Performance
Standards Under the Clean Air Act Amendments of 1977.'' \12\ The
purpose of this document was to implement the requirements of CAA
section 111(f) to develop and apply a methodology for identifying,
establishing, and prioritizing the source categories that should be
considered first for in-depth analysis prior to NSPS promulgation under
CAA section 111. For purposes of the 1978 analysis, the EPA aggregated
emissions from ``oil and gas production fields'' and ``natural gas
processing'' as part of the ``Crude Oil and Natural Gas Production
Plant'' source category. The EPA identified this aggregated source
category as a major source of hydrocarbon (HC) and SO2
emissions. When the EPA finalized the priority list in 1979, it revised
the name of the source category as ``Crude Oil and Natural Gas
Production.'' 49 FR 49222 (August 21, 1979).
---------------------------------------------------------------------------

    \12\ Priorities for New Source Performance Standards Under the
Clean Air Act Amendments of 1977. April 1978. EPA-450/3-78-019.
---------------------------------------------------------------------------

    In 1985, the EPA promulgated two rulemakings establishing NSPS for
the Crude Oil and Natural Gas Production source category. These were 40
CFR part 60, subpart KKK--Standards of Performance for Equipment Leaks
of VOC from Onshore Natural Gas Processing Plants (50 FR 26124, June
23, 1985); and subpart LLL--Standards of Performance for SO2
Emissions from Onshore Natural Gas Processing (50 FR 40160, October 1,
1985). When it first proposed 40 CFR part 60, subpart KKK, the EPA
noted that the ``crude oil and natural gas production industry
encompasses the operations of exploring for crude oil and natural gas
products, removing them from beneath the earth's surface, and
processing these products for distribution to petroleum refineries and
gas pipelines.'' \13\ The EPA repeated that description of the
identified source category when it proposed 40 CFR part 60, subpart
LLL, explaining that the ``crude oil and natural gas production
industry encompasses not only processing of the natural gas (associated
or not associated with crude oil) but operations of exploration,
drilling, and subsequent removal of the gas from porous geologic
formations beneath the earth's surface.'' \14\
---------------------------------------------------------------------------

    \13\ 49 FR 2637 (January 20, 1984).
    \14\ 49 FR 2658 (January 20, 1984).
---------------------------------------------------------------------------

    In 2012, the EPA reviewed the VOC and SO2 standards and
at the same time

established new requirements for additional stationary sources of VOC
emissions that had not been regulated in the 1985 rulemaking (e.g.,
well completions, pneumatic controllers, storage vessels, and
compressors)--``Oil and Natural Gas Sector: New Source Performance
Standards and National Emission Standards for Hazardous Air Pollutants
Reviews--Final Rule'' (77 FR 49490, August 16, 2012). In the preamble
of the 2011 proposal for the 2012 Rule, the EPA interpreted the 1979
listing as indicating that ``the currently listed Oil and Natural Gas
source category covers all operations in this industry (i.e.,
production, processing, transmission, storage and distribution).''
``Oil and Natural Gas Sector: New Source Performance Standards and
National Emission Standards for Hazardous Air Pollutants Reviews--
Proposed Rule,'' 76 FR 52738, 52745 (August 23, 2011). Further, the EPA
stated that ``[t]o the extent there are oil and gas operations not
covered by the currently listed Oil and Natural Gas source category. .
. ., we hereby modify the category list to include all operations in
the oil and natural gas sector.'' Id. The stated basis for that
proposed decision was that ``[s]ection 111(b) of the CAA gives the EPA
the broad authority and discretion to list and establish NSPS for a
category that, in the Administrator's judgment, causes or contributes
significantly to air pollution which may reasonably be anticipated to
endanger public health or welfare.'' Id. No additional discussion of
this listing position was provided in the 2011 proposal.
    In the 2012 final rulemaking, the EPA promulgated NSPS for emission
sources in the production, processing, and transmission and storage
segments, 77 FR 49492, and stated that ``[t]he listed Crude Oil and
Natural Gas Production source category covers, at a minimum, those
operations for which we are establishing standards in this final
rule.'' Id. at 49496. In responding to comments, the EPA took the
position that it was not actually revising the source category to
include emission sources in the transmission and storage segment, but
rather, was interpreting the 1979 listing to be ``broad,'' and
interpreting the 1985 rulemaking as ``view[ing] this source category
listing very broadly,'' Id. at 49514, so that, in the EPA's view, the
source category was already sufficiently broad to include that
segment.\15\
---------------------------------------------------------------------------

    \15\ In the 2012 Rule rulemaking, the EPA referred to the
distribution segment of the oil and natural gas industry, which
entails transporting natural gas to the end user. 76 FR 52738, 52745
(August 23, 2011) (proposed rule); 77 FR 49514, 77 FR 49493 (Table
2) (August 16, 2012) (final rule). However, in the 2016 Rule, the
EPA clarified that the scope of the Oil and Natural Gas Production
and Processing source category includes the transmission and storage
segment, but not the distribution segment. In addition, the EPA has
never treated any sources in the distribution segment as subject to
the requirements of NSPS subpart OOOO or OOOOa.
---------------------------------------------------------------------------

    In 2016, the EPA promulgated additional NSPS (40 CFR part 60,
subpart OOOOa) for the Crude Oil and Natural Gas Production source
category (81 FR 35824, June 3, 2016). As the EPA did in the 2012 Rule,
the EPA took the position that the 1979 listing was broad enough to
encompass the transmission and storage segment and that the 1985
rulemakings confirmed that broad listing. 81 FR 35832 (``The scope of
the 1978 Priority List is further demonstrated by the Agency's
pronouncements during the NSPS rulemaking that followed the
listing.''). The EPA stated that the inclusion of the transmission and
storage segment into the original 1979 source category was warranted
because equipment and operations at production, processing,
transmission and storage facilities are a sequence of functions that
are interrelated and necessary for getting the recovered gas ready for
distribution. Nevertheless, the EPA recognized that the scope of the
prior listing may have had some ambiguity. Accordingly, ``as an
alternative,'' the EPA finalized a revision of the category to broaden
it, so that ``[a]s revised, the listed oil and natural gas source
category includes oil and natural gas production, processing,
transmission, and storage'' and the EPA changed the source category
name to be ``Crude Oil and Natural Gas source category.'' (81 FR
35840).
a. Scope of 1979 Listing Action
    For this final rule, the EPA has reviewed the original 1979 listing
of the Crude Oil and Natural Gas Production source category and the
associated background materials and now finds that its 2012 and 2016
interpretation of the 1979 listing (i.e., that the 1979 listing
included natural gas transmission and storage) was erroneous. See
F.C.C. v. Fox Television Stations, Inc., 556 U.S. 502 (2009) (an agency
may revise its policy, but must demonstrate that the new policy is
permissible under the statute and is supported by good reasons, taking
into account the record of the previous rule). The EPA received
comments on the 2019 Proposal concerning this issue and the associated
rationale. These comments are provided, along with the EPA's responses,
in section VIII.A of this preamble and in Chapter 5 of the Response to
Comments Document for this action. None of the comments received
resulted in a change in the EPA's rationale and conclusions from
proposal. The following explains our decision.\16\
---------------------------------------------------------------------------

    \16\ In 1979, the EPA named the source category ``Crude Oil and
Natural Gas Production source category.'' In 2016, the EPA changed
the source category name to be ``Crude Oil and Natural Gas source
category.'' Because this final rule rescinds the 2016 expansion, the
EPA is finalizing the source category's name back to how it read in
1979.
---------------------------------------------------------------------------

    While the EPA has listed source categories that are broad,\17\ the
silence of the 1979 listing as to the transmission and storage segment
suggests that the segment was not considered for inclusion at the time
of the listing. Principles of administrative law require that in order
for something (in this case, the transmission and storage segment) to
be subject to regulation, the EPA should provide for and explain such
regulation clearly. Moreover, where the EPA has remained silent on any
explanation for its choice of regulation, the Court has held, ``a rule
without a stated reason is necessarily arbitrary and capricious.''
Small Refiner Lead Phase-Down Task Force v. U.S. EPA, 705 F.2d 506, 551
(1983). Accordingly, if the EPA had intended for the 1979 listing to
include the transmission and storage segment, the Agency's failure to
explain that decision would have rendered it arbitrary and capricious.
It is reasonable to presume that the Agency did not act arbitrarily and
capriciously, and, therefore, that its silence regarding the
transmission and storage segment indicated that it did not intend to
cover that segment in the 1979 listing.
---------------------------------------------------------------------------

    \17\ The EPA also has listed narrow source categories, as noted
in section VIII.A of this preamble.
---------------------------------------------------------------------------

    Additionally, to the extent there was ambiguity in the original
1979 listing, the EPA made clear its interpretation in 1984, when the
EPA proposed to set the first standards of performance for sources
within the Crude Oil and Natural Gas Production source category (i.e.,
40 CFR part 60, subpart KKK). The views the Agency expressed concerning
the scope of the source category are particularly relevant because this
rulemaking was conducted shortly after the listing and because it
established the initial NSPS. In this proposal, the EPA described the
category as ``encompass[ing] the operations of exploring for crude oil
and natural gas products, removing them from beneath the earth's
surface and processing these products for distribution to petroleum
refineries and gas pipelines,'' but this description made no reference
to the subsequent activities of transmission

and storage of crude oil and natural gas products.\18\ This description
is reasonably read to establish that sources in the transmission and
storage segment were not included in the Crude Oil and Natural Gas
Production source category as listed in 1979.
---------------------------------------------------------------------------

    \18\ 49 FR 2637; see also 49 FR 2658.
---------------------------------------------------------------------------

    Similarly, in the same sentence, the EPA defined the scope of the
source category as encompassing oil operations up to the point of
distribution to petroleum refineries, which are a separate source
category. In this manner, the EPA indicated that the Crude Oil and
Natural Gas Production source category includes operations from well
sites (exploration, drilling, and removal) and natural gas processing
plants (processing). While gathering and boosting compressor stations
were not specified, it is reasonable to conclude that they are also
included because they are located between two covered sites, the well
site and the processing plant. However, to reiterate, subsequent
operations, such as transmission and storage, and distribution were not
included.
    In the 1984 proposal, the EPA added that ``there are several VOC
emission points within this industry,'' which the Agency categorized as
process, storage, and equipment leaks. 49 FR 2637. In the 2016 NSPS,
the EPA used this description of the three sets of emission points as
support for the proposition that the Agency previously intended the
source category to include transmission and storage. Specifically, the
EPA stated that ``these emissions can be found throughout the various
segments of the natural gas industry.'' 81 FR 35832. The EPA has
closely reexamined the language of the 1984 proposal and found that,
importantly, in the descriptions of these three categories of emission
points, it is clear that the EPA considered these emission sources only
in the production and processing segments. Therefore, while it is true
that there are process, storage, and equipment leak emissions
throughout the oil and natural gas sector, the discussion in the 1984
proposal entirely focused on these sources in the production and
processing segments, and made no reference to the transmission and
storage segment. The following discusses each of those three sets of
sources in more detail.
    With respect to process sources, the 1984 proposal states that they
include well systems, field oil and natural gas separators, wash tanks,
settling tanks, and other sources. The proposal further states that
process sources remove the crude oil and natural gas from beneath the
earth and separate gas and water from the crude oil. 49 FR 2637. This
description of the process emission point clearly refers to the
production and processing segments and is silent concerning the
transmission and storage segment.
    For the second set of emission points, storage sources, the 1984
proposal states that they include field storage tanks, condensate
tanks, and cleaned oil tanks. These tanks emit VOC, the pollutant
addressed in the 1984 proposal. These three types of tanks are common
in the production segment and/or at natural gas processing plants; as
gas is separated from oil, condensate and impurities, these tanks are
used to store oil and condensate, which contain VOC. As such, these
tanks are storage sources of VOC emissions. In contrast, storage at
natural gas transmission and storage facilities refers to storage of
gas, mostly in the underground storage reservoirs. Because the gas
stored in underground reservoirs is pipeline quality natural gas (95-98
percent methane), these storage facilities in the transmission and
storage segment are not emission points of concern for VOC, or any of
the other pollutants identified in the 1984 proposal as being emitted
from the oil and gas industry. Additionally, the cited discussion in
the proposal made no explicit mention of transmission and storage
facilities. Furthermore, there are no oil tanks or field tanks in the
transmission and storage segment. As for condensate tanks, these tanks
are rarely used at the transmission and storage segment because, as
mentioned above, the gas that enters this segment is pipeline quality
gas and, therefore, contains little to no condensate. Given the
reference in the 1984 proposal to two other types of tanks that are
also commonly found in the production and processing segments but
absent in the transmission and storage segment, it is reasonable to
conclude that the proposal's reference to condensate tanks was also
intended to be limited to the production and processing segments. For
all of these reasons, the better reading of the 1984 proposal
discussion on storage tanks is that it was limited only to such tanks
located in the production and processing segments, and was not intended
to encompass tanks located in the transmission and storage segment.
    Similarly, the 1984 proposal describes the equipment leak emission
points as referring to the production and processing segments of the
Oil and Natural Gas source category and is silent concerning the
transmission and storage segment. The proposal explains that equipment
leaks of VOC can occur from ``pumps, valves, compressors, open ended
lines or valves, and pressure relief devices used in onshore crude oil
and natural gas production (emphasis added).'' Id. Additionally, the
preamble acknowledges that there is equipment used in crude oil and
natural gas production and distinguishes this from equipment used in
natural gas processing. The EPA examined the use of leak detection and
repair work practices for equipment leaks of VOC at natural gas
processing plants and explained in the preamble that the costs and
emission reduction numbers for the application of these techniques at
the ``widely dispersed'' crude oil and natural gas production sites
were not known at that time. In this manner, the EPA clearly
acknowledged the existence of equipment leaks at both the production
and processing segments. In contrast, although equipment leaks do occur
in the transmission and storage segment, the proposal makes no mention
of leaks in that segment. Thus, each of the three sets of emission
sources under consideration in the 1984 proposal clearly is in the
production and processing segments, and the proposal is silent about
the transmission and storage segment.
    Another indicator that the 1984 proposal did not consider
transmission and storage lies in the fact that this proposal addressed
VOC emissions. As discussed below, the composition of the natural gas
in the transmission and storage segment is significantly different than
in the production and processing segments, as the transmission and
storage segment contains considerably less VOC, and as a result,
sources in that segment emit low amounts of VOC. In many areas of the
country, particularly those that produce liquids and associated gas,
the production and processing segments have high VOC-content gases, but
the transmission and storage operations have substantially lower VOC-
content gases. In light of the fact that the 1979 listing concerned VOC
content (termed, at that time, HC), this difference between the
segments further supports the view that the EPA would not have included
transmission and storage in the 1979 listing. This corroborates that
the proposal did not consider emission sources related to the
transmission and storage of natural gas. Thus, although process,
storage, and equipment leaks are emission sources that are present
across the industry, including in natural gas transmission and storage,
additional examination of the 1984 proposal makes it clear that it
considered process, storage, and equipment leaks in only the production

and processing segments of the oil and natural gas industry.
    For the reasons noted above, the EPA concludes that its statements
in the 2012 and 2016 Rules that the 1979 listing of the Crude Oil and
Natural Gas Production source category included the transmission and
storage segment, and that the 1984 proposal confirmed that action, were
in error. Rather, the record of the 1979 action indicates that the
source category did not include that segment, and the Agency confirmed
that narrower scope of the source category in its 1984 proposal to
promulgate the initial set of NSPS.
b. Operations in the Transmission and Storage Segment Are Distinctly
Different
    As noted above, the 2016 Rule stated that the ``1979 listing of
[the Crude Oil and Natural Gas Production] source category provides
sufficient authority for this action'' to promulgate NSPS for sources
in the transmission and storage segment, but then added that, ``to the
extent that there is ambiguity in the prior listing, the EPA hereby . .
., as an alternative, . . . revis[es] . . . the category listing to
broadly include the oil and natural gas industry.'' \19\ ``As
revised,'' the 2016 Rule continued, ``the listed oil and natural gas
category includes oil and natural gas production, processing,
transmission, and storage.'' \20\ As discussed in the following
paragraphs, the EPA is concluding, in line with the 2019 Proposal, that
this alternative approach of revising the scope of the source category
to include sources within the transmission and storage segment was also
in error and should be rejected.
---------------------------------------------------------------------------

    \19\ 81 FR 35833.
    \20\ Id. (footnote omitted).
---------------------------------------------------------------------------

    The EPA received comments on this issue, including the associated
rationale. These comments are provided, along with the EPA's responses,
in section VIII.A of this preamble and in Chapter 5 of the Response to
Comments Document for this action. None of the comments received
resulted in a change in the EPA's rationale and conclusions from
proposal.
    While CAA section 111(b)(1)(A) and (B) respectively authorize the
EPA to ``revise,'' where warranted, both the ``list of source
categories'' and ``standards of performance'' that the EPA has
promulgated, nothing in CAA section 111 expressly authorizes or directs
the EPA to ``revise'' a particular ``source category'' by altering its
scope once the EPA has listed that source category. However, the EPA
has inherent authority to reconsider, repeal, or revise past decisions,
to the extent permitted by law, so long as the Agency provides a
reasoned explanation. See Sang Seup Shin v. INS, 750 F.2d 122, 130
(D.C. Cir. 1984) (in absence of specific statutory prohibition, an
agency has inherent authority to reconsider its decisions). The CAA
complements the EPA's inherent authority to reconsider prior
rulemakings by providing the Agency with broad authority to prescribe
regulations as necessary, under CAA section 301(a). Even so, the
authority to revise the scope of a source category must be exercised
within reasonable boundaries and cannot be employed in a way that
results in an unreasonable expansion of an existing source category.
For the reasons discussed below, the EPA is not authorized to expand
the scope of a listed source category to cover a new set of sources
that are not sufficiently related to the sources in the pre-existing
category, so that they constitute a separate source category for which
the EPA would be required to make a new SCF and endangerment finding
under CAA section 111(b)(1)(A) as a prerequisite to regulating them.
Otherwise, expanding the source category by including new sources could
be used to circumvent that requirement.
    The EPA proposed to determine that the operations in the
transmission and storage segment are not sufficiently related to the
production and processing segments that were included in the original
source category listing. In the 2016 Rule, the EPA held that the source
category should be expanded because equipment and operations at
production, processing, and transmission and storage facilities are a
sequence of functions that are interrelated and necessary for getting
the gas ready for distribution. In the 2019 Proposal, the EPA proposed
to determine that this 2016 finding was unreasonable and proposed that
transmission and storage operations are distinct from production and
processing operations because (among other things) the natural gas that
enters the transmission and storage segment has different composition
and characteristics than the natural gas that enters the production and
processing segments. 84 FR 50257.
    While CAA section 111 does not define the term ``source category''
or use the phrase ``sufficiently related,'' this concept is inherent in
the everyday definition of ``category.'' Merriam-Webster defines
``category'' as ``any of several fundamental and distinct classes to
which entities or concepts belong,'' \21\ and it defines a ``class[ ]''
as ``a group, set, or kind sharing common attributes'' (emphasis
added).\22\ Commenters point out what they view as commonalities among
both the production and processing and transmission and storage
segments. These comments implicitly acknowledge that, to be a
``category,'' the associated sources must have something in common,
that is, they must be sufficiently related to merit being associated as
part of the same category. The EPA may not have articulated the
``sufficiently related'' test in those terms in prior actions, but,
again, that test is implicit in the everyday meaning of ``category.''
That is, for items to be part of a ``category'' they must have key
things in common, and if they have substantial differences, they should
not be included in the same category. Without this test, it would be
difficult to develop a basis for ascertaining the scope of a category.
For this reason, the EPA has in effect regularly applied this test. For
example, fugitive VOC emissions from leaking equipment occurs across
several industries, including the synthetic organic chemical
manufacturing industry and the petroleum refinery industry, but there
are substantial enough differences between those industries to warrant
putting them in separate source categories, notwithstanding the fact
that some of their equipment is similar. For another example, when
proposing to expand the original Asphalt Roofing Plants source category
listing to include other locations where the preparation of asphalt for
roofing may take place, such as oil refineries, the EPA stated that,
``the emissions, processes, and applicable controls for blowing stills
and asphalt storage tanks at oil refineries and asphalt processing
plants are the same as those at asphalt roofing plants. It is therefore
reasonable to treat the asphalt processing and roofing manufacture
industry as a single category of sources for the purposes of
establishing standards of performance.'' 45 FR 76428. By finding
commonality in emissions, processes, and applicable controls for these
otherwise different sources, the EPA determined that they should be
part of the same source category.
---------------------------------------------------------------------------

    \21\ ``Category.'' Merriam-Webster.com Dictionary, Merriam-
Webster, https://www.merriam-webster.com/dictionary/category.
Accessed 21 May, 2020.
    \22\ ``Class.'' Merriam-Webster.com Dictionary, Merriam-Webster,
https://www.merriam-webster.com/dictionary/class. Accessed 19 May,
2020.

---------------------------------------------------------------------------

    In contrast, based on a reexamination of the processes and
operations found in the transmission and storage segment, the EPA is
finalizing its determination that transmission and storage sources are,
in fact, sufficiently distinct from production and processing sources
so that the Agency erred when, in the 2016 Rule, it revised the source
category to include sources in the transmission and storage segment.
Specifically, the EPA now concludes that the processes and operations
found in the transmission and storage segment are distinct from those
found in the production and processing segments because the purposes of
the operations are different and because the natural gas that enters
the transmission and storage segment has different composition and
characteristics than the natural gas that enters the production and
processing segments.
    The primary operations of the production and processing segments
are exploring crude oil and natural gas products beneath the earth's
surface, drilling wells to extract these products, and processing the
crude oil and field gas for distribution to petroleum refineries and
natural gas pipelines. As stated previously in this section, the EPA
described this source category's operations similarly when proposing 40
CFR part 60, subpart KKK, in 1984. 49 FR 2637. The primary purpose of
these segments is to obtain the product and then, in the case of
natural gas, to remove impurities from the extracted product. At a well
site (production segment), crude oil and natural gas are extracted from
the ground. Some processing can take place at the well site, such as
the physical separation of gas, production fluids, and condensate. Of
these products, crude oil and natural gas undergo successive, separate
processing. Crude oil is separated from water and other impurities and
transported to a refinery via truck, railcar, or pipeline. The EPA
treats oil refineries as a separate source category, accordingly, for
present purposes, the oil component of the production segment ends at
the point of custody transfer at the refinery.\23\ The separated gas
(``field gas'') is then sent through gathering pipelines to the natural
gas processing plant (processing segment).\24\ At the processing plant,
the field gas is converted to sales gas or pipeline quality gas. This
involves several steps, including the extraction of natural gas liquids
(e.g., a mixture of propane, butane, pentane) from the field gas, the
fractionation of these natural gas liquids into individual products
(e.g., liquid propane), or both extraction and fractionation. The final
natural gas that exits in the processing plant is sales gas, which is
predominantly methane. In these segments, the field gas has physically
changed such that it is a usable product.
---------------------------------------------------------------------------

    \23\ See 40 CFR part 60, subparts J and Ja, and 40 CFR part 63,
subparts CC and UUU.
    \24\ Natural gas with high methane content is referred to as
``dry gas,'' while natural gas with significant amounts of ethane,
propane, or butane is referred to as ``wet gas.'' The degree and
location of processing is dependent on various factors, one being
the type of natural gas (e.g., wet or dry gas). In some ``dry gas''
areas, the field gas, with naturally higher methane content, may go
from the well site directly into the transmission and storage
segment without processing in a gas processing plant. The fact that
some produced natural gas does not require processing and can be
transported directly into the transmission and storage segment does
not diminish the differences between the production and processing
segments, on the one hand, and the transmission and storage segment,
on the other. Rather, it just means that some gas does not need to
go through the processing segment.
---------------------------------------------------------------------------

    The operations of the production and processing segments differ
from the transmission and storage segment operations because in the
latter, the natural gas does not undergo changes in composition, except
for some limited removal of liquids that condensed during the
temperature and pressure changes as the natural gas moves through the
pipeline. Therefore, the natural gas that enters the transmission and
storage segment has approximately the same composition and
characteristics as the natural gas that leaves the segment for
distribution. The segment includes natural gas transmission compressor
stations, whose primary operation is to move the natural gas through
transmission pipelines by increasing the pressure. Dehydration, which
can also occur at compressor stations, is a secondary operation used
when the natural gas has collected water during transmission. As
discussed in the 2019 Proposal, this differs from the significant
natural gas processing in the production and processing segments, which
involves a series of processing steps dependent on factors such as the
type of natural gas (e.g., wet or dry gas), market conditions, and
company contract specifications. 84 FR 50258. At storage facilities,
natural gas is injected into underground storage for use during peak
seasons.\25\ When demand increases, the natural gas is extracted from
the underground storage, dehydrated to remove water that has entered
during storage, compressed, and moved through distribution pipelines.
---------------------------------------------------------------------------

    \25\ Storage can also take place in above ground storage
vessels; however, it is the EPA's understanding that these are more
commonly used after the local distribution company custody transfer
(LDC) or commonly ``city gate,'' which has not been included in the
source category at any point. The term ``local distribution company
custody transfer,'' defined in 40 CFR part 60, subpart OOOOa, means
a metering station where the LDC receives a natural gas supply from
an upstream supplier, which may be an interstate transmission
pipeline or a local natural gas producer, for delivery to customers
through the LDC's intrastate transmission or distribution lines.
This final rule adds the definition of LDC to 40 CFR part 60,
subpart OOOO.
---------------------------------------------------------------------------

    Analysis of the composition of natural gas on a nationwide basis in
the various industry segments confirms the different character of the
segments. In 2011 and subsequently in 2018, the EPA conducted an
analysis of the composition, expressed in percent volume, of natural
gas based on the methane, VOC, and HAP content across the various
industry segments.26 27 For example, in 2011, the nationwide
composition for the production segment, which included wells and
unprocessed natural gas, consisted of approximately 83-percent methane,
4-percent VOC, and less than 1-percent HAP. In contrast, the
transmission segment, which included pipeline and sales gas (i.e., post
processing), consisted of approximately 93-percent methane, 1-percent
VOC, and less than 0.01-percent HAP. In 2018, the EPA reviewed new
studies available and found similar results for the production segment.
The nationwide composition for the production segment consisted of
approximately 88-percent methane and 4-percent VOC. At proposal in
2019, we concluded that these differences in the gas composition
demonstrated that the emissions profile is different following gas
processing. After proposal in 2019, the EPA conducted a comprehensive
analysis of data reported directly to the Greenhouse Gas Reporting
Program (GHGRP) for reporting years 2015 through 2018 to determine
whether the composition of natural gas, in terms of methane content, is
statistically different between industry segments.\28\ In order to
determine whether the methane content is statistically different
between industry segments, the analysis evaluated the average methane
concentration for each segment based on the 2015-2018 GHGRP reporting
data.\29\

For oil and natural gas production, the analysis estimated an average
methane content of 69 and 83 percent, respectively. For gathering and
boosting,\30\ the analysis estimated an average methane content of 81
percent, and for gas processing, an average methane content of 78
percent. The analysis estimated an average methane content of 94
percent for transmission and 95 percent for storage. The analysis
performed additional calculations and statistical assessments to
generate the final statistical analysis and subsequent conclusions.
---------------------------------------------------------------------------

    \26\ Memorandum to Bruce Moore, U.S. EPA from Heather Brown, EC/
R. ``Composition of Natural Gas for use in the Oil and Natural Gas
Sector Rulemaking.'' July 2011. Docket ID Item No. EPA-HQ-OAR-2010-
0505-0084.
    \27\ Memorandum to U.S. EPA from Eastern Research Group.
``Natural Gas Composition.'' November 13, 2018. Docket ID No. EPA-
HQ-OAR-2017-0757.
    \28\ Memorandum. Analysis of Average Methane Concentrations in
the Oil and Gas Industry Using Data Reported Under 40 CFR part 98
Subpart W. April 9, 2020. Included in Docket ID No. EPA-HQ-OAR-2017-
0757.
    \29\ See Table 17 of Memorandum. Analysis of Average Methane
Concentrations in the Oil and Gas Industry Using Data Reported Under
40 CFR part 98 Subpart W. April 9, 2020. Included in Docket ID No.
EPA-HQ-OAR-2017-0757.
    \30\ Gathering and boosting is located between well sites and
natural gas processing plants in the Oil and Natural Gas Production
source category.
---------------------------------------------------------------------------

    This analysis found that there is a substantial difference in
methane concentrations between (1) gas production, gathering and
boosting, and gas processing and (2) transmission and storage. This
agrees with earlier data and analyses and the conclusion that there is
a difference in the emissions profile between the production and
processing segments and the transmission and storage segment.
    It should be noted that in regulating HAP from the oil and natural
gas industry, the EPA created separate source categories for the
production and processing segments, regulated under subpart HH of 40
CFR part 63; and the transmission and storage segment, regulated under
subpart HHH of 40 CFR part 63. See 64 FR 32610, June 17, 1999. In
addition, the EPA has made a similar distinction between other source
categories with segments that handle the production and processing of a
material and subsequent transport of the product. As the EPA noted in
the 2019 Proposal, 84 FR 50258, one example is the petroleum industry,
in which production facilities,\31\ refineries,\32\ and bulk gasoline
terminals \33\ all have operational differences, and the EPA placed
them in three different source categories. Those operational
differences are similar to the operational differences between the
production and processing segments and the transmission and storage
segment at issue in this final rule.
---------------------------------------------------------------------------

    \31\ U.S. EPA. ``Revised Prioritized List of Source Categories
for NSPS Promulgation.'' March 1979. EPA-450/3-79-023.
    \32\ 38 FR 15406 (May 4, 1973); 39 FR 9315 (March 8, 1974).
    \33\ 45 FR 83126 (December 12, 1980); 48 FR 37578 (August 18,
1983).
---------------------------------------------------------------------------

    It should be noted that in the 2016 Rule, the EPA justified
including the transmission and storage segment in the Crude Oil and
Natural Gas source category partly because some similar equipment
(e.g., storage vessels, pneumatic pumps, compressors) is used across
the industry. While that is true, the differences in the operations of,
and the differences in emission profiles of, the different segments
support excluding the transmission and storage segment from the source
category. A review of 2016 Rule compliance reports from sources in the
EPA Regions (3, 6, 8, 9, and 10) with the greatest oil and natural gas
activity indicates that there were no storage vessels emitting more
than 6 tons per year (tpy) VOC reported in the transmission and storage
segment.\34\ Therefore, even though there are storage vessels in the
transmission and storage segment, the liquids (condensate) stored and
the throughputs are such that the VOC emissions are significantly
different. This supports our understanding that VOC emissions are lower
in the transmission and storage segment and that any gas processing
that occurs in the transmission and storage segment generally is
limited to removing liquids that condensed during the temperature and
pressure changes as the gas moves through the pipeline. In addition,
there are types of equipment present in the production segment (e.g.,
oil tanks, three-phase separators) and processes at natural gas
processing plants (e.g., natural gas liquid extraction, natural gas
liquids fractionation, sulfur and CO2 removal) that are
either not present or uncommon at natural gas transmission and storage
facilities.
---------------------------------------------------------------------------

    \34\ These reports have since been made available for public
viewing at https://www.foiaonline.gov/foiaonline/action/public/submissionDetails?trackingNumber=EPA-HQ-2018-001886&type=request.
---------------------------------------------------------------------------

    In summary, there are distinct differences in the operations
between oil and natural gas production and natural gas processing, on
the one hand, and natural gas transmission and storage, on the other.
The primary operations of the production and processing segments are
exploring crude oil and natural gas products beneath the earth's
surface, drilling wells that are used to extract these products, and
processing the crude oil and field gas for distribution to petroleum
refineries and natural gas pipelines. The operations of the production
and processing segments differ from the transmission and storage
segment operations because in the latter, the natural gas does not
undergo changes in composition, except for some limited removal of
liquids that condensed during the temperature and pressure changes as
the natural gas moves through the pipeline. Second, there are
statistically significant differences in the emissions profiles between
the production and processing segments and the transmission and storage
segment. Third, there are equipment types and processes present in the
oil and natural gas production and processing segments that are not
present, or not common, at natural gas transmission and storage
facilities. The EPA is, therefore, finalizing a revised source category
which excludes transmission and storage sources from the Crude Oil and
Natural Gas Production source category.
    As the EPA stated in the 2019 Proposal, the 2016 Rule's expansion
of the source category to include sources in the transmission and
storage segment did, in fact, exceed the reasonable boundaries of the
EPA's authority to revise source categories. 81 FR 35833. The 2016 Rule
also erred in purporting to list, under CAA section 111(b)(1)(A), the
source category, as expanded to include transmission and storage
sources, for regulation on grounds that it causes or contributes
significantly to air pollution which may reasonably be anticipated to
endanger public health or welfare. Id. Rather, in order to include the
transmission and storage segment on the CAA section 111(b)(1)(A) list
for regulation, the EPA is required to treat it as a separate source
category and determine that in and of itself it causes or contributes
significantly to air pollution which may reasonably be anticipated to
endanger public health or welfare. The EPA did not make that
determination in the course of promulgating the 2016 Rule. 81 FR 35833.
2. Rescission of the NSPS for Sources in Transmission and Storage
Segment
    A prerequisite for the EPA to promulgate an NSPS applicable to new
sources is that the new sources must be in a source category that the
EPA has listed under CAA section 111(b)(1). As stated in section V.B.1
of this preamble, the EPA is removing the transmission and storage
segment from the source category. Accordingly, the promulgation of NSPS
for transmission and storage sources was contrary to law, and as a
result, the EPA is also rescinding the standards for both VOC and GHG
emissions in the 2012 Rule and the 2016 Rule for emission sources
located in the transmission and storage segment. Specifically, we are
rescinding the requirements for compressor affected facilities,
pneumatic controller affected facilities, storage vessel affected
facilities, and the affected facility that is the collection of
fugitive emissions components located at a compressor

station, where these affected facilities are located downstream of the
natural gas processing plant or, if no gas processing plant is present,
after the point of custody transfer. To further clarify that the
requirements do not apply to these units, we are adding a definition of
``natural gas transmission and storage segment'' which describes the
boundaries of the segment. The definitions of ``natural gas processing
plant'' and ``custody transfer'' are unchanged.
3. Status of Sources in Transmission and Storage Segment
    The result of this final rule, as it relates to the transmission
and storage segment, is that these sources are not part of a listed
source category under CAA section 111(b)(1)(A) and, thus, are not
subject to regulation under CAA section 111(b) (for new sources) or CAA
section 111(d) (for existing sources that emit certain air pollutants).
This is consistent with the treatment of emissions sources in other
industries that the EPA has not listed as a source category under CAA
section 111(b)(1)(A). In the future, the EPA may evaluate these
emissions more closely and determine whether the transmission and
storage segment should be listed as a source category under CAA section
111(b)(1)(A).\35\
---------------------------------------------------------------------------

    \35\ Methane emissions from the transmission and storage segment
are 34 MMT CO2 Eq. (1,355 kt methane) per the Inventory
of United States Greenhouse Gas Emissions and Sinks: 1990-2018
(published April 13, 2020), which amounts to 5 percent of United
States methane emissions and 0.6 percent of total U.S. GHG emissions
on a CO2 equivalent basis (using a GWP of 25 for
methane). With respect to VOC emissions, the transmission and
storage segment emitted 14 kt in 2017, which amounts to just 5.8
percent of national VOC emissions from that year. With respect to
SO2 emissions, there were 1 kt emitted from the
transmission and storage segment in 2017, or just 1.8 percent of
national SO2 emissions. For HAP emissions, the
transmission and storage segment emitted 1,143 tons in 2014, or just
0.01 percent of national HAP emissions for that year.
---------------------------------------------------------------------------

4. Rescission of the Limitations on Methane for Sources in the
Production and Processing Segments
    As the second of the two main actions of this final rule, the EPA
is also rescinding the limits on methane emissions for the NSPS
applicable to sources in the production and processing segments. The
EPA finds that, in the specific circumstances presented here, the EPA
erred in establishing the methane NSPS because those requirements are
redundant with the NSPS for VOC, establish no additional health
protections, and are, thus, unnecessary. Even if the 2016 Rule's
establishment of limits on methane emissions is not considered to be,
the EPA would exercise its discretion to rescind them on those same
grounds. Rescinding the applicability of the 2016 Rule requirements to
methane emissions, while maintaining the applicability of those
requirements to VOC emissions, will not affect the amount of methane
reductions that those requirements will achieve, because the controls
that reduce VOC emissions simultaneously reduce methane emissions.
    Comments were received on both sides of this proposed decision and
the rescission of the requirements for methane and the associated
rationale. We respond to some of the major comments in the discussion
immediately below and in section VIII.B of this preamble, and to the
rest in Chapter 6 of the Response to Comments Document. None of the
comments received have led the EPA to materially change its views from
the proposal, and as a result, the EPA is rescinding the methane NSPS.
The following is the rationale for this decision.
    In the 2016 Rule, the EPA justified regulating methane for the
following reasons: At the outset, the EPA noted that methane is a GHG,
that the EPA has determined that GHG pollution endangers public health
and welfare, and that the Crude Oil and Natural Gas Production source
category is one of the nation's largest industrial emitters of methane.
81 FR 35825. The EPA also noted that ``[r]educing methane emissions . .
. will contribute to efforts to reduce global background ozone
concentrations that contribute to the incidence of ozone-related health
effects.'' Id. at 35837. The EPA went on to determine that the amounts
of emissions of methane from the source category were sufficiently
large that it was rational to regulate them under CAA section 111, and
that, in the alternative, assuming that it was necessary to determine
that those emissions cause or contribute significantly to dangerous GHG
air pollution, the EPA made that determination as well. Id. at 35841-
43.
    The EPA recognized that the controls that facilities use to meet
the VOC NSPS ``also reduce methane emissions incidentally.'' Id. at
35841. However, the Agency added that ``in light of the current and
projected future GHG emissions from the oil and natural gas industry,
reducing GHG emissions from this source category should not be treated
simply as an incidental benefit to VOC reduction; rather, it is
something that should be directly addressed through GHG standards in
the form of limits on methane emissions under CAA section 111(b) based
on direct evaluation of the extent and impact of GHG emissions from
this source category and the emission reductions that can be achieved
through the best system for their reduction.'' Id. The Agency added,
``The standards detailed in this final action will achieve meaningful
GHG reductions and will be an important step towards mitigating the
impact of GHG emissions on climate change.'' Id.
    The EPA further justified methane requirements by noting that
``there are cost-effective controls that can simultaneously reduce both
methane and VOC emissions from these equipment across the industry, and
in many instances, they are cost effective even if all the costs are
attributed to methane reduction.'' Id. In addition, the EPA noted that
``establishing both GHG and VOC standards for equipment across the
industry will also promote consistency by providing the same regulatory
regime for this equipment throughout the oil and natural gas source
category for both VOC and GHG, thereby facilitating implementation and
enforcement.'' Id. The Agency added that, ``[w]hile this final rule
will result in additional reductions [of GHG] . . ., the EPA often
revises standards even where the revision will not lead to any
additional reductions of a pollutant because another standard regulates
a different pollutant using the same control equipment. For example, in
2014, the EPA revised the Kraft Pulp Mill NSPS in 40 CFR part 60
subpart BB published at 70 FR 18952 (April 4, 2014) to align the NSPS
standards with the National Emission Standards for Hazardous Air
Pollutants (NESHAP) standards for those sources in 40 CFR part 63,
subpart S. Although no previously unregulated sources were added to the
Kraft Pulp Mill NSPS, several emission limits were adjusted downward.
The revised NSPS did not achieve additional reductions beyond those
achieved by the NESHAP, but aligning the NSPS with the NESHAP eased the
compliance burden for the sources.'' Id. n.60.
    In F.C.C. v. Fox Television Stations, Inc., 556 U.S. 502 (2009),
the U.S. Supreme Court described the type of reasoning an agency must
provide to justify changing a rule it has previously adopted:

    We find no basis in the Administrative Procedure Act or in our
opinions for a requirement that all agency change be subjected to
more searching review. The Act mentions no such heightened standard.
And our opinion in Motor Vehicle Mfrs. Assn. of United States, Inc.
v. State Farm Mut. Automobile Ins. Co., 463 U.S. 29 (1983)

neither held nor implied that every agency action representing a
policy change must be justified by reasons more substantial than
those required to adopt a policy in the first instance. . . . The
statute makes no distinction, however, between initial agency action
and subsequent agency action undoing or revising that action.
    To be sure, the requirement that an agency provide reasoned
explanation for its action would ordinarily demand that it display
awareness that it is changing position. . . . And of course the
agency must show that there are good reasons for the new policy. But
it need not demonstrate to a court's satisfaction that the reasons
for the new policy are better than the reasons for the old one; it
suffices that the new policy is permissible under the statute, that
there are good reasons for it, and that the agency believes it to be
better, which the conscious change of course adequately indicates.
This means that the agency need not always provide a more detailed
justification than what would suffice for a new policy created on a
blank slate. Sometimes it must--when, for example, its new policy
rests upon factual findings that contradict those which underlay its
prior policy; or when its prior policy has engendered serious
reliance interests that must be taken into account. Smiley v.
Citibank (South Dakota), N. A., 517 U.S. 735, 742, 116 S.Ct. 1730,
135 L.Ed.2d 25 (1996). It would be arbitrary or capricious to ignore
such matters. In such cases it is not that further justification is
demanded by the mere fact of policy change; but that a reasoned
explanation is needed for disregarding facts and circumstances that
underlay or were engendered by the prior policy.

Id. at 514-16.
    In the 2019 Proposal, the EPA acknowledged that in the 2016 Rule,
it decided to add methane requirements even though it was aware that
the VOC requirements would, by themselves, achieve the same reductions
in methane. 84 FR 50259-60 and n.64 (citing 81 FR 35841). However, in
that proposal, the EPA nevertheless stated that upon further review, it
was proposing that it erred in 2016 by including methane requirements
and explained that those requirements were redundant to the VOC
requirements. Id. The EPA is finalizing this position for several
reasons, which meet the requirements of Fox Television for reversing
the 2016 Rule and rescinding the methane requirements.
    In the 2016 Rule, the EPA justified regulating methane on grounds
that methane emissions from this source category are great enough to
provide a rational basis for regulation in light of the dangers of GHG
air pollution and, in fact, if it were necessary, the Agency would
determine that those emissions contribute significantly to GHG air
pollution. However, in the present action, the EPA is determining that
its rational basis finding and alternative SCF in the 2016 Rule were
invalid because they included emissions from the transmission and
storage segment, as discussed in section VI of this preamble.
Accordingly, this basis \36\ in the 2016 Rule for regulating methane is
invalid.
---------------------------------------------------------------------------

    \36\ 81 FR 35833.
---------------------------------------------------------------------------

    Considering only the production and processing segments, the 2016
rational basis determination was incorrect because the methane NSPS was
redundant on the grounds that it does not achieve any additional
methane reductions beyond what sources achieve by implementing the VOC
NSPS.\37\ The EPA explained its basis for this view at length in the
2019 Proposal, noting that ``for each emission source in the source
category subject to the NSPS, the requirements overlap completely.'' 84
FR 50259. The EPA explained that each emission source in the source
category emits methane and VOC as co-pollutants through the same
emission points and processes. The requirements of the NSPS, including
the emission limits, required controls or changes in operations,
monitoring, recordkeeping, reporting, and all other requirements, apply
to each emission source's emission points and processes and, therefore,
to each emission source's methane and VOC emissions, in precisely the
same way. The capture and control devices used to meet the NSPS
requirements are the same for these co-pollutants and are not selective
with respect to either VOC or methane emissions. Id. In the proposal,
the EPA gave several examples of how the VOC and methane requirements
are duplicative of each other. Some examples include the requirements
for well affected facilities, pneumatic controllers, pneumatic pumps,
and compressors. For each of these emission points, the applicability
requirements in NSPS subpart OOOOa are entirely ``pollutant-blind.''
That is, the requirement to control is based on applicability criteria
that are not specific to VOC. For example, a pneumatic controller
affected facility is a controller operating at a natural gas bleed rate
of greater than 6 standard cubic feet per hour (scfh). The ``natural
gas'' bleed rate is based on total gas and does not consider the amount
of VOC in the gas. In fact, the VOC content could be zero. Similarly,
pneumatic pumps are affected facilities if they are ``natural gas
driven.'' All reciprocating and wet-sealed compressors, except those at
well sites, are affected facilities. Rescission of the methane
standards will have no impact on the number of affected facilities that
will be subject to the control requirements in NSPS subpart OOOOa.
Further, for well completions, pneumatic controllers, reciprocating
compressors, and pneumatic pumps at natural gas processing plants, the
control requirements are either equipment standards or work practices
that do not distinguish between VOC and methane. For pneumatic pumps,
the requirement is a 95-percent reduction in ``natural gas emissions.''
Finally, for wet-sealed centrifugal compressors, the requirement is the
only one that specifically mentions VOC or methane, as it requires a
95-percent reduction in VOC and methane. However, removal of
``methane'' will not result in any change in methane reduction as the
test method required to demonstrate this level of reduction (EPA Method
25A) measures the reduction of total organic carbon, which includes
methane.
---------------------------------------------------------------------------

    \37\ The same is true for methane reductions that reduce global
ozone levels.
---------------------------------------------------------------------------

    Thus, after the rescission of the methane standards, there will be
no change in the number of affected facilities subject to the rule.
There will also be no impact in the methane emission reductions
achieved from those sources. While commenters recognized this fact,
some raised concerns that in the future, advances in leak measurement
technology may result in situations where VOC and methane controls are
not redundant. The EPA points out that any future request for an
alternative means of emissions limitation must include a demonstration
that the alternative identifies emissions for repair that are at least
equivalent to the visible emissions observed (and repaired) using
optical gas imaging (OGI) with the current levels of sensitivity to
methane, especially where the technology speciates emissions. Section
VIII.B of this preamble, as well as Chapter 6 of the Response to
Comments Document, includes comments and responses on this topic.
Because methane reductions occur anyway as a result of the same
controls required under the VOC requirements, the benefits of the
methane reductions in protecting public health or welfare do not
justify regulation of methane under CAA section 111. By the same token,
the fact that the controls are cost effective--even, in many cases,
when all of the costs are assigned to the methane requirements--does
not justify those requirements. Again, the controls, imposed to reduce
VOC, would result in the same amount of methane reductions, even
without the methane requirements.
    Nor can the methane requirements be justified on grounds that their
overlap with VOC requirements is a means to

promote consistency by providing the same regulatory regime for this
equipment throughout the Oil and Natural Gas source category for both
VOC and methane, thereby facilitating implementation and enforcement.
Although, as noted above, the EPA regulates the same sources/same
pollutants at kraft mills under two differing rules, the requirements
were established under two different CAA regulatory programs (i.e.,
under CAA sections 111 and 112) (two different regulatory regimes). The
pollutants regulated under CAA section 111(b) for new, modified, or
reconstructed emission units at kraft pulp mills are filterable PM and
total reduced sulfur compounds. Opacity is regulated to ensure proper
operation and maintenance of the electrostatic precipitator used to
control PM emissions. Particulate matter emissions and opacity are also
regulated under a separate Federal standard, the subpart MM NESHAP for
chemical recovery combustion sources at kraft, soda, sulfite, and
stand-alone semichemical pulp mills (40 CFR part 63).
    It is rational for the EPA to determine that requirements that are
redundant to other requirements are not necessary because they do not
result in emission reductions beyond what would otherwise occur. As the
EPA noted in the 2019 Proposal, the rulemaking to promulgate NSPS for
lime manufacturing plants provides another example of the Agency
determining not to promulgate a NSPS for an air pollutant,
SO2, on grounds that the emissions were adequately
controlled by emissions controls required under a NSPS for another air
pollutant, PM. Standards of Performance for New Stationary Sources Lime
Manufacturing Plants, 42 FR 22506 (May 3, 1977). Although in that
rulemaking, the EPA did not explicitly state that SO2
controls would have been redundant and, thus, were unnecessary, the
Agency's reasoning was fully consistent with that characterization.
Specifically, the EPA noted that the controls it was requiring for PM
(a baghouse or an electrostatic precipitator) would achieve 85- to 90-
percent reductions in SO2, and that although the EPA could
impose further controls to achieve another 7 percent reduction in
SO2, based on the use of a scrubber, the cost would be too
high and the environmental benefits too little for that approach to be
appropriate. Id. at 22507. Accordingly, the EPA prescribed standards
for PM but not for SO2. Id. at 22509 (40 CFR 60.342). That
is, it appears that the EPA could have promulgated standards for
SO2 that required the same 85- to 90-percent level of
control achieved through compliance with the PM standards (and not the
additional 7 percent that would have necessitated installation of a
scrubber), but the Agency declined to do so. Even though the EPA did
not explicitly describe the potential SO2 NSPS as redundant
and, therefore, unnecessary, the fact that it did not promulgate any
standards for SO2 coupled with its explanation that PM
controls reduced SO2 by 85 to 90 percent make clear that the
rulemaking serves as a precedent for the present rulemaking and the
Agency's present position that the methane NSPS is redundant to the VOC
NSPS. By the same token, in the Lime Manufacturing Plants rule, the EPA
declined to promulgate NSPS for (1) nitrogen oxides (NOX)
because they are emitted in low concentrations or (2) CO because, among
other things, regulation would produce little environmental benefit.
Id. at 22507. These rationales for not adopting controls for those air
pollutants are similar to the redundancy rationale--the essential point
in all cases is that any controls would not result in meaningful
emission reductions.
    In a more recent rulemaking, under the Comprehensive Environmental
Response, Compensation, and Liability Act (CERCLA), the EPA also
declined to promulgate requirements that it considered to be redundant,
and the Court upheld that action. Under 42 U.S.C. 9608(b)(1), the EPA
is required to ``promulgate requirements . . . that classes of
facilities establish and maintain evidence of financial responsibility
consistent with the degree and duration of risk associated with the
production, transportation, treatment, storage, or disposal of
hazardous substances.'' In 2018, the EPA took an action in which it
declined to issue financial responsibility regulations for the hardrock
mining industry. Financial Responsibility Requirements Under CERCLA
Section 108(b) for Classes of Facilities in the Hardrock Mining
Industry (Final Action), 83 FR 7556, 7556 (February 21, 2018). As
summarized by the Court, the EPA stated that ``existing federal and
state programs as well as modern mining practices reduced the risk that
the EPA would be required to use the Superfund to finance response
actions at currently active mines.'' Idaho Conservation League v.
Wheeler, 930 F.3d 494, 501 (D.C. Cir. 2019) (citing 83 FR 7556). The
Court upheld that determination, stating that 42 U.S.C. 9608(b)(1)
``does not place any obligation on the EPA to issue redundant financial
responsibility requirements.'' Id. at 504-5.38 39
---------------------------------------------------------------------------

    \38\ In addition, as the EPA noted in the 2019 Proposal, it
``ha[s] `historically declined to propose standards for a pollutant
[that] is emit[ted] in low amounts . . . .' '' 80 FR 56599 (quoting
75 FR 54970, 54997 (September 9, 2010). This situation is similar to
the present situation in which a pollutant (methane) is fully
controlled by requirements applicable to a second pollutant (VOC).
    \39\ The EPA notes that removing the applicability of the NSPS
to methane emissions does not alter the basis for the applicability
of the NSPS to VOC emissions for affected sources in the source
category, which for some affected sources have been regulated since
the 2012 Rule. To determine the best system of emission reduction
(BSER), the EPA assesses a set of factors, which include the amount
of emissions reduction, costs, energy requirements, non-air quality
impacts, and the advancement of particular types of technology or
other means of reducing emissions, and retains discretion to weight
the factors differently in any case. In the 2016 NSPS subpart OOOOa,
the EPA gave primary weight to the amount of emission reductions and
cost. The EPA describes this analysis in depth in the 2015 NSPS
subpart OOOOa proposal at 80 FR 56618 through 56620 and 80 FR 56625
through 56627. For the source types in the production and processing
segments, the NSPS requirements, considered on a VOC-only basis, are
cost effective (relatively low cost and relatively high emissions
reductions). See memorandum titled ``Control Cost and Emission
Changes under the Amendments to 40 CFR part 60, subpart OOOOa Under
Executive Order 13783,'' in the public docket for this action. The
EPA provides this information for the benefit of the public and is
not reopening the above-described determination in the 2016 NSPS
subpart OOOOa that the VOC-only requirements for sources in the
production and processing segments meet the requirements of CAA
section 111.
---------------------------------------------------------------------------

    One commenter cites two Court cases that it asserts support the
view that the EPA must regulate a source's emissions of a particular
pollutant under CAA section 111 even where the source already controls
those emissions because of other legal obligations. In New York v.
Reilly, 969 F.2d 1147, 1153 (D.C. Cir. 1992), the Court rejected the
EPA's argument that it need not ban the burning of lead-acid vehicle
batteries under the NSPS for municipal waste combustors because the
Resource Conservation and Recovery Act precludes the burning of lead-
acid batteries. The Court responded that ``the mere existence of other
statutory authority which might undergird EPA's final stance is
insufficient to justify the omission of the battery ban.'' In Portland
Cement Ass'n v. EPA, 665 F.3d 177, 191 (D.C. Cir. 2011), the Court
rejected legal challenges to an NSPS limit for PM that tracked a
concurrently issued PM standard adopted under CAA section 112. The
Court explained that, ``[a]lthough both the NSPS and NESHAP rulemaking
resulted in a PM emissions limit of 0.01 pounds per ton, EPA arrived at
that limit using two different mechanisms,'' and added that ``the final
rule . . . noted that kilns would have to install fabric filter
technology to comply

with NESHAP, . . . and the parallel NSPS rule would therefore have no
additional cost.'' The commenter states that, similarly, while the EPA
set the same BSER for methane and VOC in the 2016 Rule, the
considerations underlying the BSER analysis differs significantly for
these pollutants, which cause distinct harms. However, these cases are
distinguishable because they stand for the proposition that when two
separate statutory requirements apply, each must be given effect, and
compliance with one does not obviate the other. In the present
rulemaking, only one statutory requirement is applicable--the CAA
section 111(b)(1)(B) requirement to promulgate standards of
performance--and the EPA has determined that promulgating a standard of
performance for VOC emissions obviates the need for a standard of
performance for methane emissions from the same sources. Further, as
the EPA noted in the 2019 Proposal, the EPA has historically declined
to propose standards for a pollutant that is emitted in small amounts.
84 FR 50260. In the case of the Oil and Natural Gas Production source
category, there are no methane emissions from the sources subject to
the NSPS beyond those emissions already subject to control by the
provisions to control VOC in the NSPS. Accordingly, there is no need to
add NSPS requirements applicable to methane.
    The EPA recognizes that in rescinding one set of standards in part
for its redundancy with another set, the EPA is choosing to rescind the
applicability of those standards to methane emissions and not VOC
emissions, rather than vice-versa. Rescinding the methane-specific
standards is reasonable because the requirements for VOC and
correspondingly, sources' compliance with those requirements, are
longer established than those for methane. As described earlier, the
EPA regulated VOC first, beginning in 1985 and continuing in 2012, and
then added regulation of methane for some sources in 2016.
    Additionally, redundancy is not uniform across affected facilities
in the production and processing segments. All sources in the segments
are subject to VOC requirements and many are subject to methane
requirements as well. However, some sources, such as storage vessels,
are subject only to VOC requirements and not methane requirements. For
those sources, it cannot be said that regulation of VOC is redundant to
regulation of methane because the EPA has not regulated methane from
them. In addition, there are no sources that are subject to only
methane requirements. For these reasons, in choosing between the two
requirements, the EPA considers it appropriate and less disruptive to
rescind the methane standards.
    Commenters asserted that the methane NSPS are not redundant to the
VOC NSPS because the former trigger the requirements in CAA section
111(d) to regulate methane from existing sources, but the VOC NSPS do
not trigger CAA section 111(d) requirements to regulate VOC from
existing sources. The commenters noted that the EPA must consider
emissions from existing sources when determining whether to list the
source category, which is the predicate to regulating a given pollutant
under CAA section 111.
    The commenters are correct that methane NSPS, but not VOC NSPS,
would trigger the CAA section 111(d) requirements for existing
sources,\40\ but the fact that the methane NSPS carries with it a
trigger for CAA section 111(d) regulation of existing sources is simply
a legal consequence of the requirements of CAA section 111, and does
not undermine the EPA's conclusion that methane NSPS are redundant. Nor
does the fact that the EPA considers emissions from existing sources in
listing the source category. These conclusions are supported by the
structure of CAA section 111. This provision establishes a multi-step
process for regulation. Section 111(b)(1)(A) of the CAA directs the EPA
to list source categories for regulation, CAA section 111(b)(1)(B)
directs the EPA then to promulgate standards of performance for
pollutants emitted from new sources, and CAA section 111(d)(1) directs
the EPA then to promulgate guidelines for states to adopt standards of
performance for certain of those pollutants emitted by existing
sources. As explained above and in responses to comments, the basis for
rescinding the applicability of the standards of performance for
methane emissions is that those NSPS are redundant with the VOC NSPS.
The legal consequence of that rescission is that the EPA is not
authorized to promulgate CAA section 111(d) guidelines for existing
sources. That consequence does not negate the fact that the methane
NSPS is redundant with the VOC NSPS.
---------------------------------------------------------------------------

    \40\ In section VII below, we finalize our proposal that VOC
NSPS do not trigger CAA section 111(d) requirements.
---------------------------------------------------------------------------

    As discussed in section VII.B of this preamble, the EPA believes
that the impact of not regulating existing oil and natural gas sources
under CAA section 111(d) will be limited due to existing factors that
encourage or require control of emissions from oil and natural gas
existing sources. For comments on that view, and the EPA's response to
those comments, see section X.B of this preamble.
    Additional comments and responses by the EPA on the rescission of
the applicability to methane are provided in section VIII.B of this
preamble and in Chapter 6 of the Response to Comments Document.
    In the next section, the EPA concludes that the 2016 Rule's
determination that methane emissions from the source category
contribute significantly to dangerous air pollution was erroneous and
must be rescinded. Rescinding that determination also requires
rescinding the methane NSPS. The redundancy of the methane requirements
and the inadequacy of the 2016 Rule's SCF for methane are separate and
independent reasons for rescinding the methane NSPS, and, thus, are
severable from each other.

VI. Significant Contribution

    The EPA is finalizing the position that the Administrator is
required to determine that methane emissions from the Crude Oil and
Natural Gas Production source category cause or contribute
significantly to GHG air pollution as a predicate for promulgating
standards of performance for methane. The EPA solicited comment on this
position in the 2019 Proposal, based on an interpretation of section
111 of the CAA, and the EPA bases this final action on a refinement of
that interpretation. Specifically, the EPA interprets the requirement
of CAA section 111(b)(1)(B) that the Administrator propose to
``establish[ ] . . . standards of performance'' and then finalize
``such standards''--together with the CAA section 111(a)(1) definition
of ``standard of performance'' as a ``standard for emissions of air
pollutants''--to limit the standards of performance to only those air
pollutants that the Administrator determined cause or contribute
significantly to dangerous air pollution when listing the source
category under CAA section 111(b)(1)(A). If the Administrator did not,
when listing the source category, determine that a particular air
pollutant causes or contributes significantly to dangerous air
pollution, then the Administrator must do so as a predicate to
promulgating standards of performance for that air pollutant.
    Section VI.A of this preamble, immediately below, discusses that
interpretation of CAA section 111. In section VI.B of this preamble, we
explain how this interpretation applies

to the regulation of methane from the Crude Oil and Natural Gas
Production source category. In section VI.C of this preamble, we
briefly discuss criteria for making a SCF under CAA section 111.

A. Legal Interpretation Concerning the Air Pollutants That Are Subject
to CAA Section 111

1. 2019 Proposal
    As noted above, CAA section 111 establishes a process for the EPA
to regulate air pollutants from industrial source categories. Section
111(b)(1)(A) of the CAA requires the first step: the Administrator must
list a particular category of stationary sources that ``causes, or
contributes significantly to, air pollution which may reasonably be
anticipated to endanger public health or welfare,'' and then, under CAA
section 111(b)(1)(B), the Administrator must proceed to promulgate
standards of performance for that source category. For convenience, we
refer to ``air pollution which may reasonably be anticipated to
endanger public health or welfare'' as dangerous air pollution, and we
refer to the reference to ``causes or contributes significantly'' as
the SCF. In the 2019 Proposal, we solicited comment on whether CAA
section 111(b)(1)(A) must be read, or reasonably could be read, to
require the Administrator to make not only a SCF to list the source
category, but also a SCF for a particular air pollutant as a predicate
to promulgating a standard of performance for that pollutant under CAA
section 111(b)(1)(B).
    The EPA supported this interpretation with a detailed discussion of
the relevant statutory provisions, their context, and purpose, as well
as past administrative practice. At the outset, the EPA acknowledged
that CAA section 111(b)(1)(A) by its terms requires that the
Administrator make a SCF for the source category, and is silent on
individual air pollutants.\41\ However, the EPA noted that CAA section
111(b)(1)(A) should be read in conjunction with CAA sections
111(b)(1)(B) and 111(a)(1), which require the Administrator to
promulgate ``standards of performance,'' defined as ``standard[s] for
emissions of air pollutants.'' The EPA posited that those provisions,
read together, by virtue of their focus on emissions of air pollutants,
could be interpreted to require or authorize the EPA to require a
pollutant-specific SCF as a predicate for promulgating a standard of
performance. 84 FR 50263. The EPA acknowledged that in the past it has
not promulgated a pollutant-specific SCF, and instead has taken the
position that it may promulgate a standard of performance for a
pollutant not previously regulated under CAA section 111 as long as it
simply has a rational basis for doing so. In the 2019 Proposal, the EPA
explained that this approach is flawed because it is vague and not
guided by any statutory criteria, and that as a result, it could result
in the Agency promulgating standards for air pollutants that are
emitted in relatively minor amounts. 84 FR 50263. The Agency stated
that interpreting CAA section 111 to require a pollutant-specific SCF
as a predicate to regulating the pollutant would guard against this
possibility.\42\
---------------------------------------------------------------------------

    \41\ It should be noted that even though CAA section
111(b)(1)(A) is clear in requiring a SCF for the source category,
its silence as to individual air pollutants, which of course are
what causes or contributes significantly to dangerous air pollution
and are the subject of regulation, leaves to the EPA the task of
addressing individual air pollutants.
    \42\ The EPA went on to review other provisions in the CAA that
explicitly require a pollutant-specific SCF; the legislative history
accompanying these provisions; the references in another CAA section
111 provision, CAA section 111(f)(2)(A) and (B), to the impacts of
particular pollutants on dangerous air pollution; and previous
interpretations that the EPA had made of the CAA section 111
requirements concerning individual air pollutants. 84 FR 50263-67.
---------------------------------------------------------------------------

2. Comments
    The EPA received comment on all aspects of its solicitation of
comment. Some commenters supported the EPA's arguments and urged the
Agency to finalize an interpretation that requires the Administrator to
make a pollutant-specific SCF as a predicate to promulgating standards
of performance for that pollutant from a source category. Other
commenters opposed this interpretation and sought to counter the
support for it that the EPA offered. They argued that under CAA section
111(b)(1)(A), the SCF applies only to source categories. They further
argued that the references in CAA sections 111(b)(1)(B) and 111(a)(1)
to air pollutants are unremarkable because standards of performance
necessarily apply to particular air pollutants, and should not be read
to elucidate the meaning of CAA section 111(b)(1)(A) in the manner the