EPA's Supplemental Proposal to Reduce Pollution from Oil and Natural Gas
Operations to Fight the Climate Crisis and Protect Public Health:

Summary of Proposed Technical Requirements: Fact Sheet
Supplemental Proposal: Highlights

•	November 11, 2022 - EPA is proposing to update, strengthen and expand its November 2021 proposal
that would secure major climate and health benefits for all Americans by reducing emissions of methane
and other harmful air pollution from both new and existing sources in the oil and natural gas industry. Oil
and natural gas operations are the nation's largest industrial source of methane, a highly potent climate
pollutant that is responsible for approximately one-third of current warming resulting from human
activities. It is also a leading source of other harmful air pollutants, including smog-forming volatile
organic compounds (VOC) and air toxics such as benzene.

•	EPA's supplemental proposal would achieve more comprehensive emissions reductions from oil and
natural gas facilities by improving standards in the 2021 proposal and adding proposed requirements for
sources not previously covered by the rules. The supplemental proposal would reduce methane
emissions from the sources it covers by 87 percent below 2005 levels, and would sharply reduce
emissions of VOCs and hazardous air pollutants that can harm health and air quality in nearby
communities.

•	The supplemental proposal also provides greater clarity for states that must develop plans to reduce
methane emissions from existing sources, and for Tribes that choose to develop plans for existing
sources in Indian country. It would give stakeholders - especially communities - a stronger voice as
states and Tribes develop plans to reduce methane from existing oil and natural gas sources. And it
includes updated requirements to ensure that existing source plans provide more rigorous and consistent
protection for public health and the environment.

•	EPA's supplemental proposal promotes innovation, reflecting input and information the Agency received
from a diverse range of perspectives during the public comment period on the November 2021 proposal.
EPA received more than 470,000 written comments on the proposal, held government-to-government
consultation with several tribal nations and held a three-day public hearing.

•	The Clean Air Act standards in the supplemental proposal will work hand-in-hand with new resources and
programs in the Inflation Reduction Act, which will incentivize early implementation of innovative
methane reduction technologies and support methane mitigation and monitoring activities. These
complementary efforts will allow the United States to achieve greater methane emissions

reductions more quickly.

•	EPA is seeking comments on all aspects of the supplemental proposal. After considering public feedback,
the Agency intends to finalize requirements for new and existing oil and gas sources that:

o Achieve the greatest possible reductions in emissions of methane and smog-forming volatile
organic compounds (VOCs),

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o Are cost-effective,
o Promote technological innovation, and
o Are anchored in science and the law.

•	The Agency plans to issue a final rule in 2023.

Benefits of the Supplemental Proposal Are Much Larger than the Costs of Compliance

•	In the supplemental proposal, EPA has updated the projected costs and benefits of all of its proposed
standards for both new and existing sources (including those in the November proposal as well as in the
supplemental proposal) to reflect improved estimates of the number of facilities covered by the rule and
the amount of VOCs and methane they emit.

•	The supplemental proposal would:

o Avoid an estimated 36 million tons of methane emissions from 2023 to 2035, the equivalent of 810
million metric tons of carbon dioxide - nearly the same as all greenhouse gases emitted from coal-
fired electricity generation in the U.S. in 2020.

o In 2030 alone, the proposal would reduce methane emissions from covered sources by an
estimated 87 percent compared to 2005.

o Avoid smog-forming VOC emissions by 9.7 million tons from 2023 to 2035, along with 390,000 tons
of toxic air pollutants like benzene and toluene, among others.

o Yield $3.1 to $3.2 billion in climate benefits per year, with total net benefits valued at $34 to $36
billion from 2023 through 2035.

o Increase recovery of natural gas - valued at $3.3 to $4.6 billion from 2020 through 2035 - that
otherwise would go to waste.

•	These estimates may understate the benefits of the supplemental proposal because they do not include
reductions identified through EPA's proposed Super-Emitter Response Program. Super emitters may be
responsible for a large portion of total emissions from the oil and natural gas sector.

•	Because EPA has updated its modeling approach to reflect the newest information and improved
analyses, the emissions reductions and costs and benefits estimates are not directly comparable to the
numbers from the November proposal.

•	EPA's assessment of the benefits of the proposed rule also includes a supplementary analysis that
incorporates the most recent scientific advances into updated estimates of the economic harm
associated with each ton of greenhouse gas pollution. The Agency is making a technical report explaining
the basis for these estimates available for public comment as part of the supplemental proposal. EPA also
is seeking peer review of the technical report.

Summary of proposed requirements

•	This fact sheet summarizes many of the requirements included in the supplemental proposal. The
following links will take you to specific sections of the fact sheet.

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Dates the Rules Would Applv

Alternative Technology
Approval

Liquids Unloading

Well Site and Compressor
Station Monitoring
Requirements

Super Emitter Response
Program

Flares and Combustion Control
Devices

Well Closure Requirements

Pneumatic Pumps

Centrifugal Compressors

Innovative Methane Detection
technologies

Pneumatic Controllers

Reciprocating Compressors

Continuous Methane
Detection Technologies

Associated Gas

Storage Tanks

•	Please refer to the text of the supplemental proposal to read all of the proposed requirements.

Dates the rules would apply

•	EPA is proposing to strengthen Clean Air Act requirements from its November 2021 proposal, including:

o New Source Performance Standards (NSPS) under section 111(b) of the law to reduce emissions
of methane and smog-forming volatile organic compounds (VOCs) from new, modified and
reconstructed sources; and
o The first nationwide Emissions Guidelines under section 111(d) for states that would be required
to develop plans to limit methane emissions from existing sources.

•	Some oil and natural gas sources that were subject to previous NSPS would become subject to existing
source standards under state plans. The table below shows which rule applies based on a source's
construction date:

When it was built (or
reconstructed/modified)

Which rule applies

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

NSPS issued in 2012 (also referred to as OOOO)

*Note: Existing sources built on or before November 15, 2021,* will
become subject to state plans under the Emissions Guidelines once
those take effect

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

NSPS issued in 2016 (also referred to as OOOOa)

*Note: Existing sources built on or before November 15, 2021,* will
become subject to state plans under the Emissions Guidelines once
those take effect.

After November 15, 2021

NSPS that will be finalized in 2023 (also referred to as OOOOb)

*For existing dry seal compressors, this date would be on or before the date that the supplemental proposal is published in

the Federal Register

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Key requirements in the supplemental proposal:

•	Under section 111(b) of the Clean Air Act, EPA must set NSPS and Emission Guidelines for each type of
regulated source by applying the "best system of emission reduction," or "BSER," that the Administrator
determines has been adequately determined.

•	In developing the supplemental proposal, EPA evaluated new data made available to the Agency, along
with information and public comment received on the November 2021 proposal. EPA used the data and
information to conduct new analyses to determine an updated BSER for several of the sources covered
by the rule. A summary of the proposed standards is below:

Requiring Routine Monitoring for Leaks at Every Well Site, Until Wells Are Properly Closedand at
Compressor Stations

•	After considering information and comments received from the public, EPA is revising its November
2021 proposal to find and fix leaks (fugitive emissions) at new and existing well sites. The Agency's
new approach would ensure that every well site, regardless of size, is regularly inspected for leaks.

•	The revised program would tie monitoring requirements to the types and amount of equipment at a
site rather than to estimated emissions. This approach removes exemptions from routine
monitoring for well sites with lower emissions, including well-head only well sites, which EPA had
proposed in 2021. The supplemental proposal creates a cost-effective approach to ensure that all
well sites are regularly checked for leaks.

•	EPA is proposing monitoring and repair programs for four categories of well sites:
o Single wellhead-only well sites;

o Well head only well sites with two or more wellheads;

o Well sites and centralized production facilities with major production and processing equipment;
and

o Small well sites. (Small well sites are single wellhead well sites that have no controlled storage
vessels, control devices, pneumatic controller affected facilities or pneumatic pump affected
facilities, and include only one other piece of major production and processing equipment.)

Well Closure Requirements

•	EPA's November 2021 proposal noted that abandoned and unplugged wells can be a significant
source of methane and other air pollutants. To ensure that well sites are not left unplugged and
potentially leaking, EPA is now proposing that monitoring must continue at these sites until all wells
have been plugged, equipment has been removed, and no fugitive emissions are present.

o Owners would have to submit a well closure plan that includes the necessary steps to close the
wells, including plugging all wells, documentation of financial assurance to complete the well
closure and a schedule for completing closure activities.

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o Once a well site is closed, owners/operators would have to conduct a final survey using OGI to
ensure no emissions are found. If emissions are detected, the owners/operators would have to
make repairs according to the schedule for leaks found with OGI and resurvey the site.

• The table below summarizes the proposed requirements for well sites, showing both the proposed
Best System of Emission Reduction (BSER) and the proposed standards.

Summary of Proposed Leaks Monitoring Requirements for New and Modified Well Sites *
(Proposed Presumptive Methane Standards for the Emissions Guidelines are the Same)

(table continues on next page)

Type of site Proposed BSER Proposed monitoring and repair

requirements

Single wellhead-only sites

• Quarterly AVO (audio, visual,
olfactory) inspections

•	Quarterly AVO inspections, repair
identified leaks within 15 days.

•	Monitoring must continue until the
well site has been closed including
plugging the wells at the site and
submitting a well closure report

Wellhead-only sites with two or
more wellheads

• Quarterly AVO inspections and
monitoring and repair based on
semiannual monitoring using OGI

•	Quarterly AVO inspections, repair
identified leaks within 15 days.

•	Semiannual OGI monitoring (or
optional semiannual monitoring using
EPA method 21 with 500 ppm defined
as a leak)

•	First attempt at repair within 30 days
of finding a leak using OGI; final repair
within 30 days of the first attempt.

•	Monitoring must continue until the
well site has been closed including
plugging the wells at the site and
submitting a well closure report

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Type of site Proposed BSER Proposed monitoring and repair

requirements

Sites with major production and
processing equipment and
centralized production facilities

•	AVO monitoring every other month
and

•	Monitoring and repair based on
quarterly monitoring using OGI (for
well sites with specified major
production and processing
equipment)

•	AVO monitoring every other month;
repair for indications of potential leaks
within 15 days of inspection AND

•	For well sites with specified production
and processing equipment: Quarterly
OGI monitoring (optional quarterly EPA
Method 21 monitoring with 500 ppm
define as a leak)

•	First attempt at repair within 30 days
of finding a leak; final repair within 30
days of the first attempt.

•	Monitoring must continue until the
well site has been closed including
plugging the wells at the site and
submitting a well closure report

Small well sites

(These are single wellhead well
sites with no controlled storage
tanks, control devices, pneumatic
controller affected facilities or
pneumatic pump affected
facilities) and only one other
piece of major production and
processing equipment.)

• Quarterly AVO (audio, visual
olfactory) inspections

•	Quarterly AVO inspections, repair
identified leaks within 15 days.

•	Monitoring must continue until the
well site has been closed including
plugging the wells at the site and
submitting a well closure report

Compressor stations

• Monthly AVO monitoring AND
monitoring and repair base on
quarterly monitoring using OGI

•	Monthly AVO monitoring AND

•	Quarterly OGI monitoring (option to
use quarterly EPA Method 21
monitoring with 500 ppm defined as a
leak)

•	First attempt at repair within 30 days
of finding a leak; final repair within 30
days of the first attempt.

* Well sites and compressor stations on the Alaska North Slope would be subject to annual monitoring using OGI.

EPA is proposing that owners and operators monitoring for leaks at well sites follow OGI procedures
outlined in the proposed NSPS regulatory text instead of the proposed Appendix K. Read a fact sheet on
the proposed update to Appendix K.

Innovative Technologies

• EPA received overwhelming support for allowing owners and operators the flexibility to use advanced
methane detection technologies to monitor for leaks (or "fugitive emissions").

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•	In the supplemental proposal, the Agency would provide a pathway for the use of a broader range of
advanced technologies in lieu of optical gas imaging (OGI) or EPA Method 21. This pathway is a
technology-neutral approach that ties the frequency of required monitoring surveys to the detection
ability of the technology used, while keeping the same deadlines for repairs as OGI.

•	This "matrix approach" would provide multiple options for conducting methane screening surveys while
providing incentives for continued advancement of methane detection technology. EPA is also proposing
a streamlined process to approve these screening technologies, with clearly defined requirements for
those seeking EPA approval to use these alternative test methods.

•	The table below shows the proposed survey matrix for well sites with major production and processing
equipment, controlled storage vessels, natural gas-driven pneumatic controllers, associated covers and
closed vent systems, and control devices, centralized production facilities, and compressor stations.

Proposed Survey Matrix for Alternative Periodic Screening Approach for
Affected Facilities Subject To Quarterly OGI Monitoring for Methane

(proposed requirements for the NSPS and the Emissions Guidelines are the same)

Minimum Screening Frequency

Minimum Detection Threshold of
Screening Technology

Quarterly + Annual OGI

<1 kilograms per hour (kg/hr)

Bimonthly

<2 kg/hr

Monthly

<4 kg/hr

Bimonthly + Annual OGI

<10 kg/hr

Monthly + Annual OGI

<30 kg/hr

• The next table shows the proposed survey matrix for single and multi- wellhead-only sites and small well
sites. The minimum detection threshold is based on a 90 percent probably of detection:

Proposed Survey Matrix for Alternative Periodic Screening Approach
for Single and Multi-Wellhead-Only Sites And Small Well Sites

(proposed requirements for the NSPS and the Emissions Guidelines are the same)

Minimum Screening Frequency

Minimum Detection Threshold of
Screening Technology

Semiannual

<1 kilograms per hour (kg/hr)

Triannual

<2 kg/hr

Triannual + Annual OGI

<5 kg/hr

Quarterly + Annual OGI

<15 kg/hr

Monthly + Annual OGI

<30 kg/hr

• To reflect changes to the proposed alternative periodic screening approach, EPA is proposing to allow
owners and operators to use any applicable approved alternative screening approach as long as they
develop a site-specific monitoring plan that details the use of the alternative screening approach, and
notify the Administrator that they are using it.

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•	The supplemental proposal would require owners and operators to conduct an initial periodic monitoring
survey within:

o 90 days of the startup of production for each "fugitive emissions component affected facility"
and/or storage vessel affected facility that is located at a new, modified, or reconstructed well
site or centralized production facility and that has not begun any fugitive monitoring;

o 90 days of startup for each fugitive emissions components affected facility and storage vessel
affected facility located at a new compressor station; and

o 90 days of modification for each fugitive emissions components affected facility and storage
vessel affected facility located at a modified compressor station.

•	When a periodic survey identified emissions, owners/operators would be required to conduct a ground-
based survey using OGI to identify the source of the emissions and any other leaks present. Repairs
would be required within 30 days of the screening survey.

o In addition, if the ground-based survey confirms that leaks were caused by a control device
failure, owners and operators would have to begin a root cause analysis and determine
appropriate corrective action within 24 hours for fugitive emissions components, and take the
corrective action as soon as possible.

o For covers and controlled vent systems, if a leak or defect is identified, owners and operators
would have to conduct a root cause analysis to determine the cause of the leak within five days
of complaint the ground-based survey and take actions to resolve the emissions and ensure there
are no detectable emissions, which is the standard for covers and controlled vent systems. EPA is
seeking comment on an appropriate deadline for completing all corrective actions.

Continuous Technologies

•	The supplemental proposal would also give owners and operators the option to use continuous
monitoring technologies that operate around the clock to check for methane leaks and that can
determine site-level emissions at least once every 12 hours.

•	Owners or operators using continuous technologies would be required to determine the cause of a leak
and take corrective action whenever emissions exceed an action level at the boundary of a regulated
facility. This approach is similar to the approach used in the fenceline monitoring requirements in EPA's
air toxics rules for petroleum refineries.

•	EPA is proposing two action levels for continuous monitoring, which are designed to address both smaller
leaks that persist over time as well as large leaks or malfunctions.

Proposed Alternative Continuous Monitoring Approach for New and Modified Well Sites

(Presumptive Methane Standards for the Emissions Guidelines are the Same)

Type of site

Type of Action Level

Proposed monitoring and repair requirements

Wellhead-only sites

Long-term

1.2 kilograms per hour (kg/hr), rolling 90-day
average calculated each day

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Type of site

Type of Action Level

Proposed monitoring and repair requirements

Wellhead-only sites

Short-term

15 kg/hr, rolling seven-day average calculated
each day

Other well sites and
compressor stations

Long-term

1.6 kg/hr, rolling 90-day average calculated each
day

Other well sites and
compressor stations

Short-term

21 kg/hr rolling seven-day average calculated each
day

Alternative Technology Approval

•	EPA is also encouraging the continued development of innovative technologies by proposing a clear
and streamlined pathway for technology developers and others to seek approval for using advanced
technologies to monitor for methane. Once the Agency approves a technology and technique, owners
and operators would be able to use it widely without the need for additional approval.

•	EPA is proposing to require owners and operators who want to use an alternative technology that has
not yet been approved to seek approval under the Agency's alternative test method provisions, rather
than though site-specific monitoring plans.

•	If the alternative method has been approved and is broadly applicable, EPA will post it to the Agency's
Emission Measurement Center website. Owners and operators would identify the approved method
they intend to use in their leak monitoring plans.

•	EPA is proposing clear requirements to streamline these approvals, including basic eligibility criteria to
apply for approval and necessary information about the screening technology and its capabilities. EPA
is proposing to approve or disapprove an alternative technology application, in writing, within 270
days.

•	The Agency also is proposing to allow conditional approval if it has not made a determination by that
deadline. EPA would make the approvals and supporting information available to the public on an EPA-
supported website.

Super Emitter Response Program

•	Studies show that emissions from a small number of sources are responsible for as much as half of the
methane emissions from oil and natural gas operations, along with significant amounts of smog-
forming VOCs and air toxics that are of concern in many communities. These large emissions events,
known as "super emitters," often are caused by malfunctions or abnormal operating conditions,
including unlit flares and open thief hatches on storage tanks.

•	While many of EPA's proposed requirements would reduce the number of super emitters, EPA also is
proposing a Super-Emitter Response Program to quickly identify these events for prompt mitigation.
EPA is proposing to define a super-emitting event as emissions of 100 kilograms (220.5 pounds) of
methane per hour or larger, with a focus on super emitters at an individual well site, centralized
production facility, compressor station, or natural gas processing plant.

•	The Super-Emitter Response Program would leverage expertise and data from regulatory agencies or
EPA-approved qualified third parties with access to EPA-approved remote methane detection
technology.

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•	Under the proposed program, regulatory authorities or qualified third parties that have been approved
by EPA could notify owners and operators of regulated facilities when a super emitter is detected.

o Notifiers could be any technology vendors, industry, researchers, non-profit organizations, or
other parties demonstrating technical expertise in the use of the detection technology and the
interpretation or analysis of the data the technology collects.

o The notifiers would have to provide credible, well-documented identification of the event, using
one of several allowed remote-sensing technologies and approaches. Each notification must
contain specific information to help owners and operators verify that the emissions are correctly
linked to their site, and to help them swiftly identify the source of the super emitter.

o EPA would maintain a public list of approved qualified third-party notifiers, so owners and
operators can verify approval before being required to act on a notification.

•	Once they are notified, owners and operators would be required to conduct a root cause analysis and,
where appropriate, take corrective actions to address the source of emissions.

o If the owner or operator confirms the existence of a super-emitter emissions event that requires
mitigation, it must take prompt steps to eliminate the super-emitter emissions event and report
both its root-cause analysis and corrective actions to the EPA and the appropriate state or tribal
authority.

•	EPA also is proposing a mechanism for owners and operators to seek a revocation of a notifier's EPA
certification if they establish that more than one notification contained demonstrable errors.

•	To ensure this program operates in a transparent manner, the EPA will make available in a document
repository the notices to operators that the EPA receives, as well as the reports sent to the EPA by
owners and operators in response, so that notifiers, communities, and owners and operators have
quick access to the information submitted to the EPA under the super-emitter provisions.

•	The table below summarizes the proposed requirements for super emitters, showing both the
proposed Best System of Emission Reduction (BSER) and the proposed standards.

Summary of Proposed Requirements for Super Emitters

(Presumptive Methane Standards for the Emissions Guidelines are the Same)

Type of site

Proposed BSER

Proposed requirements

Super-emitter sites

Root cause analysis and

• Root cause analysis withing five days of receiving a



corrective action following

notification of a super-emitter event AND



notification of super-emitter
emissions event.

• Corrective action, if needed, following notification of
super-emitter emissions event.

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Pneumatic Pumps

•	The supplemental proposal would update the definition of "affected facility" for pneumatic pumps to
be the collection of all natural gas-driven diaphragm and piston pumps a well site, centralized
production facility, onshore natural processing plant, or compressor station.

•	EPA is proposing to require pneumatic pumps to have zero methane and VOC emissions. This means
pumps used at an affected facility should not be driven by natural gas.

•	At sites that do not have access to electricity, owners/operators would be allowed to use natural gas-
driven pneumatic pumps if they demonstrate that it is not technically feasible to use pneumatic pumps
that are not driven by natural gas. In these cases, owners/operators would have to use the emissions
from the gas-driven pumps by routing them to a process on site. If routing emissions to a process is not
feasible, owner/operators would have to control emissions, with the requirement depending on the
number of pumps on site.

•	The table below summarizes the proposed requirements for pneumatic pumps, showing both the
proposed Best System of Emission Reduction (BSER) and the proposed standards.

Summary of Proposed Requirements for Pneumatic Pumps

Type of source

Proposed BSER

Proposed requirements

Pneumatic pumps

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

•	Proposed NSPS: Methane and VOC emission rate = zero

•	Proposed presumptive methane standards under the
Emissions Guidelines: methane emission rate = zero

Pneumatic Controllers

•	EPA is proposing to update the definition of "affected facility" for pneumatic controllers, based on
comments the Agency received on the November proposal.

•	Under the supplemental proposal, a pneumatic controller affected facility would be the collection of
continuous bleed and intermittent vent natural gas-driven controllers at a well site, centralized
production facility, onshore natural processing plant or compressor station. This would include two
types of natural gas-driven controllers that previously were excluded from coverage: controllers where
emissions are routed to a sales line or used for onsite fuel or another useful purpose, and self-
contained natural gas pneumatic controllers. The supplemental proposal clarifies that these controllers,
which should not emit methane and VOCs if they are properly maintained, can be used to meet a zero-
emissions standard.

•	Like the November proposal, the supplemental proposal would require pneumatic controller affected
facilities to have zero methane and VOC emissions, with the exception of natural gas-driven pneumatic
controllers that function as emergency shutdown devices, pneumatic controllers that are not driven by
natural gas, and pneumatic controllers at sites in Alaska that do not have power.

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• The table below summarizes the proposed requirements for pneumatic controllers, showing both the
proposed Best System of Emission Reduction (BSER) and the proposed standards.

Summary of Proposed Requirements for Pneumatic Controllers

Type of source

Proposed BSER

Proposed requirements

Natural gas-driven pneumatic
controllers that vent to the
atmosphere

Use of zero-emissions
controllers

•	Proposed NSPS: VOC and methane emission rate = zero

•	Proposed presumptive methane standards under the
Emissions Guidelines: methane emission rate = zero

*Pneumatic controllers at sites in Alaska where onsite power is not available would have different requirements.

Additional Requirements for Wells

• EPA is proposing to update the definition of affected facility for wells to be a single well. The Agency is
updating proposed requirements for associated gas from oil wells and for well liquids unloading.

Associated Gas from Oil Wells

•	EPA is proposing to limit the use of flares for eliminating venting of associated gas from oil wells.

•	The supplemental proposal allows owners and operators four compliance options to reduce or
eliminate emissions of methane and VOC from associated gas from oil wells. They are:

o Route the gas to a sales line;

o Recover the associated gas from the separator and use the recovered gas as an onsite fuel
source;

o Recover the associated gas from the separator and use the recovered gas for another useful
purpose that a purchased fuel or raw material would serve; or

o Recover the associated gas from the separator and reinject the recovered gas into the well or
inject the recovered gas into another well for enhanced oil recovery.

•	The supplemental proposal would allow flaring of the gas only if the owner or operator demonstrates
that all four compliance options are infeasible due to technical or safety reasons, and that
demonstration is approved by a certified professional engineer. In these situations, owners and
operators would have to use a flare or other control device that reduces methane and VOC emissions
by 95 percent.

Summary of Proposed Requirements for Oil Wells with Associated Gas
(Presumptive Methane Standards for the Emissions Guidelines are the Same)

Type of source

Proposed BSER

Proposed requirements

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

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

Liquids Unloading

•	The supplemental proposal no longer considers all liquids unloading at existing wells to be a
modification.

•	EPA is proposing a presumptive standard of zero methane emissions for liquids unloading events at
existing wells, which aligns with the standard for liquids unloading at new and modified wells. That
standard would require liquids unloading to be conducted with zero methane and VOC emissions.

•	Where it is technically infeasible or not safe to meet the zero emissions standard, the Agency is
proposing to require that owners and operators employ best management practices to minimize
venting of emissions to the maximum extent possible.

•	In addition, the Agency is proposing reporting requirements for well liquids unloading operations.
Owners and operators who use methods that vent to the atmosphere would have to document why
it is not feasible to use a non-venting method for technical, safety or economic reasons, along with
the best management practices used to minimize emissions during each liquids unloading operation.

Summary of Proposed Requirements for Well Liquids Unloading
(Presumptive Methane Standards for the Emissions Guidelines)

Type of source



Proposed BSER

Proposed requirements

Well Liquids Unloading

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

Proposed presumptive standards under the
Emissions Guidelines: Perform liquids unloading
with zero methane or VOC emissions. If this is not
feasible for safety or technical reasons, employ best
management practices to minimize venting of
emissions to the maximum extent possible.
The proposed presumptive standards are the same
as those proposed for the NSPS in November 2021.

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Flare and Combustion Control Devices

•	EPA is proposing that control devices used for any affected facility must demonstrate that they meet a 95
percent VOC and methane emission reduction requirement through a performance test or
manufacturer's performance test. For condensers and carbon adsorbers this can be done through a
design evaluation.

•	The Agency also is proposing several requirements to ensure that all flares and enclosed combustion
devices operate properly. Those include requirements that flares and enclosed combustors:

o Have a continuous pilot flame and install a continuous parameter monitoring system capable of
monitoring for the presence of a pilot or combustion flame at least once every 5 minutes;

o Are inspected monthly (or at other times as requested by the EPA Administrator) for visible
emissions using section 11 of EPA Method 22, with an observation period of 15 minutes to
determine whether the flare is exceeding the visible emissions limit;

o Are monitored for the net heating value of the vent gas sent to the flare or combustor. Owners
and operators would install a continuous parameter monitoring system, such as a calorimeter, to
continuously determine the net heating value of the gas sent to the flare or combustor; and

o Have a continuous parameter monitoring system to determine the flow of gas sent to the flare or
combustor, except as noted below for pressure-assisted devices.

•	The supplemental proposal includes alternative compliance options for some of these requirements.

Centrifugal Compressors

Wet seal centrifugal compressors

•	EPA is proposing to require that emissions from new, modified and reconstructed wet seal centrifugal
compressors reduce methane and VOC emission by 95 percent. This can be achieved by capturing and
routing emissions from the wet seal degassing system to a combustion device. As a compliance
alternative, EPA is proposing to allow owners and operators to meet the 95 percent reduction
requirement by routing the emissions to a process.

•	For existing wet seal compressors, EPA is proposing a presumptive standard of a volumetric flow rate of 3
standard cubic feet per minute (scfm) to prevent emissions. As a compliance alternative, EPA is proposing
to allow owners and operators to reduce methane emissions by 95 percent or greater by routing
emissions to a control device or to a process.

•	Self-contained wet seal centrifugal compressors would have to comply with the standard for dry seal
compressors.

Dry seal centrifugal compressors

•	In the November 2021 proposal, EPA sought comment on whether the Agency should consider
developing standards for dry seal compressors. Based on information the Agency received, EPA is

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proposing standards for new and existing dry seal compressors, which previously have not been
regulated.

• Owners or operators of dry seal compressors would be required to maintain the volumetric flow rate at
or below 3 scfm to prevent emissions.

Summary of Proposed Requirements for Centrifugal Compressors

Type of source

Proposed BSER

Proposed requirements

Wet seal centrifugal
compressors (except those
located at well sites)

NSPS: capture and route emissions
from the wet seal fluid degassing
system to a control device

NSPS: 95 percent reduction of methane and VOC
emissions



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

Presumptive methane standards for the Emissions
Guidelines: Volumetric flow rate of 3 scfm.

Dry seal centrifugal
compressors (except those
located at well sites)

NSPS and Emissions Guidelines:
Conduct preventative
maintenance and repair to
maintain flow rate at or below 3
standard cubic feet per minute
(scfm)

NSPS and presumptive methane standards for the
Emissions Guidelines: Volumetric flow rate of 3 scfm

Reciprocating Compressors

• EPA is proposing several changes to the standard the Agency proposed in November for reciprocating
compressors:

o Changes to the format of the standard - EPA is proposing a numerical emission limit. Owners and
operators would be required to keep emissions below a flow rate of 2 scfm.

¦ As a compliance alternative, owners and operator would be allowed to route emissions to
a process via a closed vent system, but this would not have to occur under negative
pressure.

o Repair or replacement - Owners would be allowed to replace rod packing and/or conduct other
necessary repairs and maintenance to keep emissions below this rate.

o Periodic flow rate monitoring - EPA is proposing to allow for periodic flow rate monitoring based
on 8,760 hours of operation instead of requiring monitoring on a calendar year basis.

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Summary of Proposed Requirements for Reciprocating Compressors
(Presumptive Methane Standards for the Emissions Guidelines are the Same)

Type of source

Proposed BSER

Proposed requirements

Reciprocating compressors
(except those located at well
sites)

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

Volumetric flow rate of 2 scfm.

Storage tanks

•	The supplemental proposal would update the definition of tank battery. EPA is proposing to define a tank
battery as a group of storage tanks that are manifolded together for transferring liquids. A tank battery
also could include a single tank, if only one is present at the site, or if the tanks at the site are not
manifolded together for transferring liquids.

•	EPA also is proposing to update the applicability requirements for new, modified and reconstructed tank
batteries. In the November proposal, tank batteries would be subject to requirements to reduce
methane and VOC emissions by 95 percent if their potential VOC emissions were 6 tons per year or
higher. The supplemental proposal would add potential methane emissions to that threshold, meaning
tank batteries would be required to reduce methane and VOC emissions by 95 percent emissions if their
potential VOC emissions are 6 tons per year or higher or their potential methane emissions are 20 tons
per year or higher.

•	In addition, the Agency is proposing that a "generally accepted model or calculation methodology" used
to determine VOC and methane emissions must account for flashing, working and breathing losses. The
supplemental proposal includes regulatory text that instructs the owner or operator on how to
determine the potential for VOC or methane emissions as the cumulative emissions from all storage
vessels within the tank battery, according to certain timelines.

Summary of Proposed Requirements for Storage Vessels

Type of source Proposed BSER Proposed requirements

NSPS; A single storage vessel
or tank battery with potential
to emit (PTE) 6 tpy or more
of VOC and PTE of 20 tpy or
more of methane

Capture and route to a control
device.

NSPS: 95 percent reduction of VOC and methane
(same as in November proposal)

Emissions Guidelines: Tank
battery with PTE of 20 tpy or
more of methane (same as in
November proposal).

Capture and route to a control
device.

Emissions Guidelines: 95 percent reduction of
methane (same as in November proposal)

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Other Proposed Updates

•	EPA also is proposing updates to requirements for:

o Covers and closed vent systems;
o Equipment leaks at natural gas processing plants; and
o Sweetening units.

•	In addition, the Agency is proposing updates to recordkeeping and reporting requirements.

Content of the Proposed Rules (Regulatory Text)

•	EPA is providing the content (regulatory text) reflecting the proposed NSPS (referred to as OOOOb) and
the proposed Emissions Guidelines (referred to as 0000c). The proposed regulatory text is available in
the docket for the supplemental proposal and on EPA's website.

Proposed Requirements for State Plans

•	The supplemental proposal also includes a number of updates to requirements for state plans limiting
methane emissions from existing sources under the proposed Emissions Guidelines. Read a fact sheet
about proposed requirements for states.

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