[Federal Register Volume 81, Number 167 (Monday, August 29, 2016)]
[Rules and Regulations]
[Pages 59331-59384]
[FR Doc No: 2016-17687]

Vol. 81

Monday,

No. 167

August 29, 2016

Part III

Environmental Protection Agency

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

40 CFR Part 60

Standards of Performance for Municipal Solid Waste Landfills; Final
Rule

Federal Register / Vol. 81 , No. 167 / Monday, August 29, 2016 /
Rules and Regulations

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

ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 60

[EPA-HQ-OAR-2003-0215; FRL-9949-51-OAR]
RIN 2060-AM08

Standards of Performance for Municipal Solid Waste Landfills

AGENCY: Environmental Protection Agency (EPA).

ACTION: Final rule.

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

SUMMARY: The Environmental Protection Agency (EPA) is finalizing a new
subpart that updates the Standards of Performance for Municipal Solid
Waste Landfills. Under section 111 of the Clean Air Act, the EPA must
review, and, if appropriate, revise standards of performance at least
every 8 years. The EPA's review of the standards for municipal solid
waste landfills considered landfills that commence construction,
reconstruction, or modification after July 17, 2014. The final
standards also reflect changes to the population of landfills and an
analysis of the timing and methods for reducing emissions. This action
will achieve additional reductions in emissions of landfill gas and its
components, including methane, by lowering the emissions threshold at
which a landfill must install controls. This action also incorporates
new data and information received in response to the proposed
rulemaking and addresses other regulatory issues including surface
emissions monitoring, wellhead monitoring, and the definition of
landfill gas treatment system.
    The new subpart will reduce emissions of landfill gas, which
contains both nonmethane organic compounds and methane. Landfills are a
significant source of methane, which is a potent greenhouse gas
pollutant. These avoided emissions will improve air quality and reduce
the potential for public health and welfare effects associated with
exposure to landfill gas emissions.

DATES: This final rule is effective on October 28, 2016.
    The incorporation by reference of certain publications listed in
the regulations is approved by the Director of the Federal Register as
of October 28, 2016.

ADDRESSES: The EPA has established a docket for this action under
Docket ID No. EPA-HQ-OAR-2003-0215. All documents in the docket are
listed in the http://www.regulations.gov index. Although listed in the
index, some information is not publicly available, e.g., Confidential
Business Information (CBI) or other information whose disclosure is
restricted by statute. Certain other material, such as copyrighted
material, is not placed on the Internet and will be publicly available
only in hard copy form. Publicly available docket materials are
available electronically through http://www.regulations.gov.

FOR FURTHER INFORMATION CONTACT: For information concerning this final
rule, contact Ms. Hillary Ward, Fuels and Incineration Group, Sector
Policies and Programs Division, Office of Air Quality Planning and
Standards (E143-05), Environmental Protection Agency, Research Triangle
Park, NC 27711; telephone number:<PHONE_NUMBER>; fax number: (919)
541-0246; email address<EMAIL_ADDRESS>
SUPPLEMENTARY INFORMATION:
    Acronyms and Abbreviations. The following acronyms and
abbreviations are used in this document.

ANPRM Advance notice of proposed rulemaking
ANSI American National Standards Institute
BMP Best management practice
BSER Best system of emission reduction
Btu British thermal unit
CAA Clean Air Act
CA LMR California Landfill Methane Rule
CBI Confidential business information
CDX Central Data Exchange
CEDRI Compliance and Emissions Data Reporting Interface
CFR Code of Federal Regulations
CO2 Carbon dioxide
CO2e Carbon dioxide equivalent
EIA Energy Information Administration
EPA Environmental Protection Agency
ERT Electronic Reporting Tool
FID Flame ionization detector
GCCS Gas collection and control system
GHG Greenhouse gas
GHGRP Greenhouse Gas Reporting Program
GWP Global warming potential
HAP Hazardous air pollutant
HOV Higher operating value
IAMS Integrated assessment models
ICR Information collection request
IPCC Intergovernmental Panel on Climate Change
IWG Interagency working group
lb/MMBtu Pounds per million British thermal unit
LFG Landfill gas
LFGCost Landfill Gas Energy Cost Model
m\3\ Cubic meters
Mg Megagram
Mg/yr Megagram per year
mph Miles per hour
MSW Municipal solid waste
mtCO2e Metric tons of carbon dioxide equivalent
MW Megawatt
MWh Megawatt hour
NAICS North American Industry Classification System
NESHAP National Emission Standards for Hazardous Air Pollutants
NMOC Nonmethane organic compound
NRC National Research Council
NSPS New source performance standards
NTTAA National Technology Transfer and Advancement Act
OAQPS Office of Air Quality Planning and Standards
OMB Office of Management & Budget
PM Particulate matter
PM2.5 Fine particulate matter
ppm Parts per million
RCRA Resource Conservation and Recovery Act
RD&D Research, development, and demonstration
RFA Regulatory Flexibility Act
RIA Regulatory Impact Analysis
SBAR Small Business Advocacy Review
SC-CH4 Social cost of methane
SC-CO2 Social cost of carbon dioxide
SEM Surface emissions monitoring
SER Small entity representative
SO2 Sulfur dioxide
SSM Startup, shutdown, and malfunction
Tg Teragram
TTN Technology Transfer Network
U.S. United States
USGCRP U.S. Global Change Research Program
VCS Voluntary consensus standard
VOC Volatile organic compound
WWW World Wide Web

    Organization of This Document. The following outline is provided to
aid in locating information in this preamble.

I. Executive Summary
    A. Purpose of Regulatory Action
    B. Summary of Major Provisions
    C. Costs and Benefits
II. General Information
    A. Does this action apply to me?
    B. Where can I get a copy of this document and other related
information?
III. Background
    A. Landfill Gas Emissions and Climate Change
    B. What are the public health and welfare effects of landfill
gas emissions?
    C. What is the EPA's authority for reviewing the NSPS?
    D. What is the purpose and scope of this action?
    E. How would the changes in applicability affect sources
currently subject to subparts Cc and WWW?
IV. Summary of the Final NSPS
    A. What are the control requirements?
    B. What are the monitoring, recordkeeping, and reporting
requirements?
    C. Startup, Shutdown, and Malfunction Provisions
    D. Other Corrections and Clarifications
V. Summary of Significant Changes Since Proposal
    A. Changes to Monitoring, Recordkeeping, and Reporting
    B. Tier 4
    C. Changes To Address Closed or Non-Productive Areas
    D. Startup, Shutdown, and Malfunction Provisions
    E. Definitions for Treated Landfill Gas and Treatment System and
Treatment System Monitoring

    F. Other Corrections and Clarifications
VI. Rationale for Significant Changes Since Proposal
    A. Changes To Monitoring, Recordkeeping, and Reporting
    B. Tier 4
    C. Changes To Address Closed or Non-Productive Areas
    D. Startup, Shutdown, and Malfunction Provisions
    E. Definitions of Treated Landfill Gas and Treatment System
    F. Other Corrections and Clarifications
VII. Impacts of This Final Rule
    A. What are the air quality impacts?
    B. What are the water quality and solid waste impacts?
    C. What are the secondary air impacts?
    D. What are the energy impacts?
    E. What are the cost impacts?
    F. What are the economic impacts?
    G. What are the benefits?
VIII. Statutory and Executive Order Reviews
    A. Executive Order 12866: Regulatory Planning and Review and
Executive Order 13563: Improving Regulation and Regulatory Review
    B. Paperwork Reduction Act (PRA)
    C. Regulatory Flexibility Act (RFA)
    D. Unfunded Mandates Reform Act (UMRA)
    E. Executive Order 13132: Federalism
    F. Executive Order 13175: Consultation and Coordination With
Indian Tribal Governments
    G. Executive Order 13045: Protection of Children From
Environmental Health Risks and Safety Risks
    H. Executive Order 13211: Actions That Significantly Affect
Energy Supply, Distribution, or Use
    I. National Technology Transfer and Advancement Act (NTTAA) and
1 CFR Part 51
    J. Executive Order 12898: Federal Actions To Address
Environmental Justice in Minority Populations and Low-Income
Populations
    K. Congressional Review Act (CRA)

I. Executive Summary

A. Purpose of Regulatory Action

    This action finalizes changes to the Standards of Performance for
Municipal Solid Waste (MSW) Landfills (landfills new source performance
standards or landfills NSPS) resulting from the EPA's review of the
landfills NSPS under Clean Air Act (CAA) section 111. The EPA's review
identified a number of advances in technology and operating practices
for reducing emissions of landfill gas (LFG) and the final changes are
based on our evaluation of those advances and our understanding of LFG
emissions. In order to avoid possible confusion regarding which MSW
landfills would actually be subject to these requirements, the EPA is
establishing a new subpart XXX (40 CFR part 60, subpart XXX) rather
than merely updating the existing subpart WWW (40 CFR part 60, subpart
WWW). The requirements in new subpart XXX apply to MSW landfills for
which construction, reconstruction, or modification commenced after
July 17, 2014, the date of the proposed rule. The requirements in
subpart WWW continue to apply to MSW landfills for which construction,
reconstruction, or modification was commenced on or after May 30, 1991
and on or before July 17, 2014. For a discussion of how changes in
applicability affect sources currently subject to subparts Cc and WWW,
see the proposed Emission Guidelines (80 FR 52110, August 27, 2016).
    The resulting changes to the NSPS found in subpart XXX will achieve
additional reductions in emissions of LFG and its components, including
methane. This final rule is consistent with the President's 2013
Climate Action Plan,\1\ which directs federal agencies to focus on
``assessing current emissions data, addressing data gaps, identifying
technologies and best practices for reducing emissions, and identifying
existing authorities and incentive-based opportunities to reduce
methane emissions.'' The final rule is also consistent with the
President's Methane Strategy,\2\ which directs the EPA's regulatory and
voluntary programs to continue to pursue emission reductions through
regulatory updates and to encourage LFG energy recovery through
voluntary programs. These directives are discussed in detail in section
III.A of this preamble. This regulatory action also resolves and
clarifies several implementation issues that were previously addressed
in amendments proposed on May 23, 2002 (67 FR 36475) and September 8,
2006 (71 FR 53271).
---------------------------------------------------------------------------

    \1\ Executive Office of the President, ``The President's Climate
Action Plan'' June 2013. https://www.whitehouse.gov/sites/default/files/image/president27sclimateactionplan.pdf.
    \2\ Executive Office of the President, ``Climate Action Plan
Strategy to Reduce Methane, March 2014. https://www.whitehouse.gov/sites/default/files/strategy_to_reduce_methane_emissions_2014-03-28_final.pdf.
---------------------------------------------------------------------------

1. Need for Regulatory Action
    Several factors led to today's final action. First, section 111 of
the Clean Air Act (CAA) (42 U.S.C. 7411) requires the EPA to review
standards of performance at least every 8 years and, if appropriate,
revise the standards to reflect improvements in methods for reducing
emissions. Second, a mandatory duty lawsuit was filed against the EPA
for failure to review the NSPS by the statutorily required deadline.
Under a consent decree resolving that lawsuit, the EPA agreed to
propose a review and take final action on the proposal. Third, the EPA
has concluded that landfill owners or operators, as well as regulators,
need clarification regarding issues that have arisen during
implementation of the existing standards. Implementation issues include
the definition of LFG treatment, among other topics. Fourth, landfills
are a significant source of methane, a very potent greenhouse gas, for
which there are cost-effective means of reduction, so this rule is an
important element of the United States' work to reduce emissions that
are contributing to climate change.
2. Legal Authority
    CAA section 111(b)(1)(B) (42 U.S.C. 7411(b)(1)(B)) requires the EPA
to ``at least every 8 years review and, if appropriate, revise'' new
source performance standards. CAA section 111(a)(1) (42 U.S.C.
7411(a)(1)) provides that performance standards are to ``reflect the
degree of emission limitation achievable through the application of the
best system of emission reduction which (taking into account the cost
of achieving such reduction and any nonair quality health and
environmental impact and energy requirements) the Administrator
determines has been adequately demonstrated.'' We refer to this level
of control as the best system of emission reduction or ``BSER.''
    As indicated above, the EPA has decided to finalize its review of
the landfill NSPS in a new subpart rather than update existing
requirements in 40 CFR part 60, subpart WWW. The EPA believes that
either approach is legally permissible.\3\ The final subpart XXX will
appear in 40 CFR part 60 and will apply to landfills that commence
construction, reconstruction, or modification after July 17, 2014.
---------------------------------------------------------------------------

    \3\ The EPA believes that it has the legal authority in updating
an NSPS to either propose and make changes to the existing subpart
or to promulgate a new subpart and has previously done both. In
either case, any substantive changes to the NSPS apply only to
sources for which construction, reconstruction, or modification
commenced on or after the date on which the proposed changes were
published in the Federal Register (July 17, 2014).
---------------------------------------------------------------------------

B. Summary of Major Provisions
    The final NSPS apply to landfills that commenced construction,
reconstruction, or modification after July 17, 2014 (the date of
publication of the proposed NSPS). The final rule provisions are
described below.
    Thresholds for Installing Controls. The final NSPS retain the
current design capacity threshold of 2.5 million megagrams (Mg) and 2.5
million cubic meters (m\3\), but reduce the nonmethane

organic compounds (NMOC) emission threshold for the installation and
removal of a gas collection and control system (GCCS) from 50 megagrams
per year (Mg/yr) to 34 Mg/yr. An MSW landfill that exceeds the design
capacity threshold must install and start up a GCCS within 30 months
after LFG emissions reach or exceed an NMOC level of 34 Mg/yr. (A
megagram is also known as a metric ton, which is equal to 1.1 United
States (U.S.) short tons or about 2,205 pounds.) Consistent with the
existing NSPS (40 CFR part 60, subpart WWW), the owner or operator of a
landfill may control the gas by routing it to a non-enclosed flare, an
enclosed combustion device, or a treatment system that processes the
collected gas for subsequent sale or beneficial use.
    Emission Threshold Determination. The EPA is finalizing an
alternative site-specific emission threshold methodology for when a
landfill must install and operate a GCCS. This alternative methodology,
referred to as ``Tier 4,'' is based on surface emission monitoring
(SEM) and demonstrates whether or not surface emissions are below a
specific threshold. The Tier 4 SEM demonstration allows landfills that
exceed the threshold using modeled NMOC emission rates using Tier 1 or
2 to demonstrate that actual site-specific surface methane emissions
are below the threshold. A landfill that can demonstrate that surface
emissions are below 500 parts per million (ppm) for four consecutive
quarters does not trigger the requirement to install a GCCS even if
Tier 1, 2, or 3 calculations indicate that the 34 Mg/yr threshold has
been exceeded. Landfills that have calculated NMOC emissions of 50 Mg/
yr or greater are not eligible for the Tier 4 emission threshold
determination in order to prevent conflicting requirements between
subpart XXX and the landfills NESHAP (40 CFR part 63, subpart AAAA).
Many landfills that are subject to subpart XXX will also be subject to
the landfills NESHAP. The landfills NESHAP requires landfills that
exceed the size threshold (2.5 million Mg and 2.5 million m\3\) and
exceed the NMOC emissions threshold (50 Mg/yr) to install and operate a
GCCS.
    Low LFG Producing Areas. The EPA is also finalizing criteria for
determining when it is appropriate to cap or remove all or a portion of
the GCCS. The final criteria for capping or removing all or a portion
of the GCCS are: (1) The landfill is closed, (2) the GCCS has operated
for at least 15 years or the landfill owner or operator can demonstrate
that the GCCS will be unable to operate for 15 years due to declining
gas flows, and (3) the calculated NMOC emission rate at the landfill is
less than 34 Mg/yr on three successive test dates.
    Landfill Gas Treatment. In the final NSPS, the EPA has addressed
two issues related to LFG treatment. First, the EPA is clarifying that
the use of treated LFG is not limited to use as a fuel for a stationary
combustion device but may be used for other beneficial uses such as
vehicle fuel, production of high-British thermal unit (Btu) gas for
pipeline injection, or use as a raw material in a chemical
manufacturing process. Second, the EPA is finalizing the definition of
treated landfill gas that applies to LFG processed in a treatment
system meeting the requirements in 40 CFR part 60, subpart XXX and
defining treatment system as a system that filters, de-waters, and
compresses LFG for sale or beneficial use. The definition of treatment
system allows the level of treatment to be tailored to the type and
design of the specific combustion equipment or the other beneficial
uses such as vehicle fuel, production of high-Btu gas for pipeline
injection, or use as a raw material in a chemical manufacturing process
in which the LFG is used. Owners or operators must develop a site-
specific treatment system monitoring plan that includes monitoring
parameters addressing all three elements of treatment (filtration, de-
watering, and compression) to ensure the treatment system is operating
properly for the intended end use of the treated LFG. They also must
keep records that demonstrate that such parameters effectively monitor
filtration, de-watering, and compression system performance necessary
for the end use of the treated LFG.
    Wellhead Operational Standards. The EPA is finalizing changes to
certain operational standards (i.e., the requirement to meet specific
operating limits) for nitrogen/oxygen level at the wellheads. Landfill
owners or operators are not required to take corrective action based on
exceedances of specified operational standards for nitrogen/oxygen
levels at wellheads, but they must continue to monitor and maintain
records of nitrogen/oxygen levels on a monthly basis in order to inform
any necessary adjustments to the GCCS and must maintain records of
monthly readings. The operational standard, corrective action, and
corresponding recordkeeping and reporting remain for temperature and
maintaining negative pressure at the wellhead.
    Surface Monitoring. The EPA is finalizing the requirement to
monitor all surface penetrations at landfills. In final 40 CFR part 60,
subpart XXX, landfills must conduct SEM at all cover penetrations and
openings within the area of the landfill where waste has been placed
and a gas collection system is required to be in place and operating
according to the operational standards in final 40 CFR part 60, subpart
XXX. Specifically, landfill owners or operators must conduct surface
monitoring on a quarterly basis at the specified intervals and where
visual observations indicate elevated concentrations of LFG, such as
distressed vegetation and cracks or seeps in the cover and all cover
penetrations.
    Startup, Shutdown, and Malfunction. The EPA is finalizing a
requirement that standards of performance in the NSPS apply at all
times, including periods of startup, shutdown, and malfunction (SSM).
The EPA is also finalizing an alternative standard during SSM events:
In the event the collection or control system is not operating, the gas
mover system must be shut down and all valves in the collection and
control system that could contribute to venting of the gas to the
atmosphere must be closed within 1 hour of the collection or control
system not operating.
    Other Clarifications. The EPA is finalizing a number of
clarifications to address several issues that have been raised by
landfill owners or operators during implementation of the current NSPS
and Emission Guidelines. These clarifications include adding criteria
for when an affected source must update its design plan and clarifying
when landfill owners or operators must submit requests to extend the
timeline for taking corrective action. The EPA is also updating several
definitions in the NSPS. In addition, while the EPA is not mandating
organics diversion, we are finalizing two specific compliance
flexibilities in the NSPS to encourage wider adoption of organics
diversion and GCCS Best Management Practices (BMPs) for emission
reductions at landfills. These compliance flexibilities are discussed
in sections VI.A.1 and VI.A.2 (wellhead monitoring) and section V.B and
VI.B (Tier 4 emission threshold determination) of this preamble.

C. Costs and Benefits

    The final NSPS are expected to significantly reduce emissions of
LFG and its components, which include methane, volatile organic
compounds (VOC), and hazardous air pollutants (HAP). Landfills are a
significant source of methane emissions, and in 2014 landfills
represented the third largest source of human-related methane emissions
in the U.S. This rulemaking applies to landfills that commence

construction, modification, or reconstruction after July 17, 2014. In
the 5 years following July 17, 2014, the EPA estimates that 14
landfills will commence construction and 123 landfills will modify.
Note that landfills are not expected to reconstruct (63 FR 32745, June
16, 1998).
    To comply with the emissions limits in the final rule, owners or
operators of new or modified MSW landfills are expected to install the
least-cost control for collecting and treating or combusting LFG. The
annualized net cost for the final NSPS is estimated to be $6.0 million
(2012$) in 2025, when using a 7 percent discount rate. The annualized
costs represent the costs compared to no changes to the current NSPS
(i.e., baseline) and include $11 million to install and operate a GCCS,
as well as $0.08 million to complete the corresponding testing and
monitoring. These control costs are offset by $5.1 million in revenue
from electricity sales, which is incorporated into the net control
costs for certain landfills that are expected to generate revenue by
using the LFG to produce electricity.
    Installation of a GCCS to comply with the 34 Mg/yr NMOC emissions
threshold at new or modified landfills would achieve reductions of 281
Mg/yr NMOC and 44,300 Mg/yr methane (about 1.1 million metric tons of
carbon dioxide equivalent per year (mtCO2e/yr)) beyond the
baseline in year 2025. In addition, the final rule is expected to
result in the net reduction of 26,000 Mg-CO2, due to reduced
demand by landfills for electricity from the grid as landfills generate
electricity from LFG. The NMOC portion of LFG can contain a variety of
air pollutants, including VOC and various organic HAP. VOC emissions
are precursors to both fine particulate matter (PM2.5) and
ozone formation. These pollutants, along with methane, are associated
with substantial health effects, welfare effects, and climate effects.
The EPA expects that the reduced emissions will result in improvements
in air quality and lessen the potential for health effects associated
with exposure to air pollution related emissions, and result in climate
benefits due to reductions of the methane component of LFG.
    The EPA estimates that the final rule's estimated methane emission
reductions and secondary CO2 emission reductions in the year
2025 would yield global monetized climate benefits of $31 million to
approximately $180 million, depending on the discount rate. Using the
mean social cost of methane (SC-CH4) and social cost of
CO2 (SC-CO2), at a 3-percent discount rate,
results in an estimate of about $68 million in 2025 (2012$).
    The SC-CH4 and SC-CO2 are the monetary values
of impacts associated with marginal changes in methane and
CO2 emissions, respectively, in a given year. Each metric
includes a wide range of anticipated climate impacts, such as net
changes in agricultural productivity, property damage from increased
flood risk, and changes in energy system costs, such as reduced costs
for heating and increased costs for air conditioning.
    With the data available, we are not able to provide quantified
health benefit estimates for the reduction in exposure to HAP, ozone,
and PM2.5 for this rule. This is not to imply that there are
no such benefits of the rule; rather, it is a reflection of the
difficulties in modeling the direct and indirect impacts of the
reductions in emissions for this sector with the data currently
available.
    Based on the monetized benefits and costs, the annual net benefits
of the standards are estimated to be $62 million ($2012) in 2025, based
on the average SC-CH4 at a 3 percent discount rate, average
SC-CO2 at a 3 percent discount rate, and costs at a 7
percent discount rate.

II. General Information

A. Does this action apply to me?

    This final rule addresses MSW landfills that are new,
reconstructed, or modified after July 17, 2014, and associated solid
waste management programs. Potentially affected categories include
those listed in Table 1 of this preamble.

                                           Table 1--Regulated Entities
----------------------------------------------------------------------------------------------------------------
                    Category                            NAICS \a\             Examples of affected facilities
----------------------------------------------------------------------------------------------------------------
Industry: Air and water resource and solid                        924110  Solid waste landfills
 waste management.
Industry: Refuse systems--solid waste landfills                   562212  Solid waste landfills
State, local, and tribal government agencies...                   924110  Administration of air and water
                                                                           resource and solid waste management
                                                                           programs
----------------------------------------------------------------------------------------------------------------
\a\ North American Industry Classification System.

    This table is not intended to be exhaustive, but rather provides a
guide for readers regarding entities likely to be regulated by the new
subpart. To determine whether your facility would be regulated by this
action, you should carefully examine the applicability criteria in
final 40 CFR 60.760 of subpart XXX. If you have any questions regarding
the applicability of the final subpart to a particular entity, contact
the person listed in the preceding FOR FURTHER INFORMATION CONTACT
section.

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

    In addition to being available in the docket, an electronic copy of
this action is available through EPA's Technology Transfer Network
(TTN) Web site, a forum for information and technology exchange in
various areas of air pollution control. Following signature by the EPA
Administrator, the EPA will post a copy of this action at http://www.epa.gov/ttnatw01/landfill/landflpg.html. 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 Web site.

III. Background

    On July 17, 2014, the EPA proposed a new NSPS subpart (40 CFR part
60, subpart XXX) based on its ongoing review of the MSW Landfills NSPS
(40 CFR part 60, subpart WWW) (79 FR 41796). On August 27, 2015 (80 FR
52162), the EPA issued a supplemental proposal to achieve additional
reductions of LFG and its components, including methane, through a
lower emission threshold at which MSW landfills must install and
operate a GCCS. On August 27, 2015, the EPA issued a concurrent
proposal for revised Emission Guidelines for existing MSW Landfills (80
FR 52100). The EPA considered information it received in response to an
Advanced Notice of Proposed Rulemaking (ANPRM) for the MSW landfills
Emission Guidelines (79 FR 41772) and a Notice of Proposed Rulemaking
for existing landfills (80 FR 52100), in addition to the Notice of

Proposed Rulemaking for new landfills (79 FR 41796), in evaluating
these final provisions for new sources.

A. Landfill Gas Emissions and Climate Change

    In June 2013, President Obama issued a Climate Action Plan that
directed federal agencies to focus on ``assessing current emissions
data, addressing data gaps, identifying technologies and best practices
for reducing emissions, and identifying existing authorities and
incentive-based opportunities to reduce methane emissions.'' \4\
Methane is a potent greenhouse gas (GHG) that is 28-36 times greater
than carbon dioxide (CO2) and has an atmospheric life of
about 12 years.\5\ Because of methane's potency as a GHG and its
atmospheric life, reducing methane emissions is one of the best ways to
achieve near-term beneficial impacts in mitigating global climate
change.
---------------------------------------------------------------------------

    \4\ Executive Office of the President, ``The President's Climate
Action Plan'' June 2013. https://www.whitehouse.gov/sites/default/files/image/president27sclimateactionplan.pdf.
    \5\ The IPCC updates GWP estimates with each new assessment
report, and in the latest assessment report, AR5, the latest
estimate of the methane GWP ranged from 28-36, compared to a GWP of
25 in AR4. The impacts analysis in this final rule is based on AR4
instead of AR5 (i.e., a GWP of 25) to be consistent with and
comparable to key Agency emission quantification programs such as
the Inventory of Greenhouse Gas Emissions and Sinks (GHG Inventory),
and the GHGRP.
---------------------------------------------------------------------------

    The ``Climate Action Plan: Strategy to Reduce Methane Emissions''
\6\ (the Methane Strategy) was released in March 2014. The strategy
recognized the methane reductions achieved through the EPA's regulatory
and voluntary programs to date. It also directed the EPA to continue to
pursue emission reductions through regulatory updates and to encourage
LFG energy recovery through voluntary programs.
---------------------------------------------------------------------------

    \6\ Executive Office of the President, ``Climate Action Plan
Strategy to Reduce Methane'', March 2014. https://www.whitehouse.gov/sites/default/files/strategy_to_reduce_methane_emissions_2014-03-28_final.pdf.
---------------------------------------------------------------------------

    The EPA recognized the climate benefits associated with reducing
methane emissions from landfills nearly 25 years ago. The 1991 NSPS
Background Information Document \7\ asserted that the reduction of
methane emissions from MSW landfills was one of many options available
to reduce global warming. The NSPS for MSW landfills, promulgated in
1996, also recognized the climate co-benefits of controlling methane
(61 FR 9917, March 12, 1996).
---------------------------------------------------------------------------

    \7\ Air Emissions from Municipal Solid Waste Landfills-
Background Information for Proposed Standards and Guidelines, U.S.
EPA (EPA-450/3-90-011a) (NTIS PB 91-197061) page 2-15.
---------------------------------------------------------------------------

    A recent study assessed EPA regulations and voluntary programs over
the period 1993-2013 and found that they were responsible for the
reduction of about 130 million metric tons of methane emissions (equal
to about 18 percent of the total U.S. methane emissions over that time
period), leading to a reduction in atmospheric concentrations of
methane of about 28 parts per billion in 2013 \8\ (compared to an
observed increase in methane concentrations of about 80 ppb over those
20 years).
---------------------------------------------------------------------------

    \8\ Melvin, A.M.; Sarofim, M.C.; Crimmins, A.R., ``Climate
benefits of U.S. EPA programs and policies that reduced methane
emissions 1993-2013'', Environmental Science & Technology, 2016, in
press. http://pubs.acs.org/doi/pdf/10.1021/acs.est.6b00367. DOI
10.1021/acs.est.6b00367.
---------------------------------------------------------------------------

    The review and final revision of the MSW landfills NSPS capitalizes
on additional opportunities to achieve methane reductions while
acknowledging historical agency perspectives and research on climate, a
charge from the President's Climate Action Plan, the Methane Strategy,
and improvements in the science surrounding GHG emissions.
    LFG is a collection of air pollutants, including methane and NMOC.
LFG is typically composed of 50-percent methane, 50-percent
CO2, and less than 1-percent NMOC by volume. The NMOC
portion of LFG can contain various organic HAP and VOC. When the
Emission Guidelines and NSPS were promulgated in 1996, NMOC was
selected as a surrogate for MSW LFG emissions because NMOC contains the
air pollutants that at that time were of most concern due to their
adverse effects on health and welfare. Today, methane's effects on
climate change are also considered important. In 2014, methane
emissions from MSW landfills represented 18.2 percent of total U.S.
methane emissions and 1.9 percent of total U.S. GHG emissions (in
carbon dioxide equivalent (CO2e)).\9\ In 2014, MSW landfills
continued to be the third largest source of human-related methane
emissions in the U.S., releasing an estimated 133.1 million metric tons
of CO2e.\10\ For these reasons and because additional
emissions reductions can be achieved at a reasonable cost, the EPA is
finalizing changes to the NSPS that are based on reducing the NMOC and
methane components of LFG.
---------------------------------------------------------------------------

    \9\ Total U.S. methane emissions were 731 Teragram (Tg)
CO2e and total U.S. GHG emissions were 6,870.5 Tg in
2014. A teragram is equal to 1 million Mg. (A megagram is also known
as a metric ton, which is equal to 1.1 U.S. short tons or about
2,205 pounds.) U.S. EPA ``Inventory of U.S. Greenhouse Gas Emissions
and Sinks: 1990-2014.'' Table ES-2. Available at http://www.epa.gov/climatechange/ghgemissions/usinventoryreport.html.
    \10\ Ibid, Section 7. Waste, Table 7-3.
---------------------------------------------------------------------------

B. What are the public health and welfare effects of landfill gas
emissions?

1. Health Effects of VOC and Various Organic HAP
    VOC emissions are precursors to both PM2.5 and ozone
formation. As documented in previous analyses (U.S. EPA, 2006,\11\
2010,\12\ and 2014[hairsp]\13\), exposure to PM2.5 and ozone
is associated with significant public health effects. PM2.5
is associated with health effects, including premature mortality for
adults and infants, cardiovascular morbidity such as heart attacks, and
respiratory morbidity such as asthma attacks, acute bronchitis,
hospital admissions and emergency room visits, work loss days,
restricted activity days and respiratory symptoms, as well as welfare
impacts such as visibility impairment.\14\ Ozone is associated with
health effects, including hospital and emergency department visits,
school loss days and premature mortality, as well as ecological effects
(e.g., injury to vegetation and climate change).\15\ Nearly 30 organic
HAP have been identified in uncontrolled LFG, including benzene,
toluene, ethyl benzene, and vinyl chloride.\16\ Benzene is a known
human carcinogen.
---------------------------------------------------------------------------

    \11\ U.S. EPA. RIA. National Ambient Air Quality Standards for
Particulate Matter, Chapter 5. Office of Air Quality Planning and
Standards, Research Triangle Park, NC. October 2006. Available on
the Internet at http://www.epa.gov/ttn/ecas/regdata/RIAs/
Chapter%205_Benefits.pdf.
    \12\ U.S. EPA. RIA. National Ambient Air Quality Standards for
Ozone. Office of Air Quality Planning and Standards, Research
Triangle Park, NC. January 2010. Available on the Internet at http://www.epa.gov/ttn/ecas/regdata/RIAs/s1-supplemental_analysis_full.pdf.
    \13\ U.S. EPA. RIA. National Ambient Air Quality Standards for
Ozone. Office of Air Quality Planning and Standards, Research
Triangle Park, NC. December 2014. Available on the Internet at
http://www.epa.gov/ttnecas1/regdata/RIAs/20141125ria.pdf.
    \14\ U.S. EPA. Integrated Science Assessment for Particulate
Matter (Final Report). EPA-600-R-08-139F. National Center for
Environmental Assessment--RTP Division. December 2009. Available at
http://cfpub.epa.gov/ncea/cfm/recordisplay.cfm?deid=216546.
    \15\ U.S. EPA. Air Quality Criteria for Ozone and Related
Photochemical Oxidants (Final). EPA/600/R-05/004aF-cF. Washington,
DC: U.S. EPA. February 2006. Available on the Internet at http://cfpub.epa.gov/ncea/CFM/recordisplay.cfm?deid=149923.
    \16\ U.S. EPA. 1998. Office of Air and Radiation, Office of Air
Quality Planning and Standards. ``Compilation of Air Pollutant
Emission Factors, Fifth Edition, Volume I: Stationary Point and Area
Sources, Chapter 2: Solid Waste Disposal, Section 2.4: Municipal
Solid Waste Landfills''. Available at: http://www.epa.gov/ttn/chief/ap42/ch02/final/c02s04.pdf.

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

2. Climate Impacts of Methane Emissions
    In addition to the improvements in air quality and resulting
benefits to human health and the non-climate welfare effects discussed
above, reducing emissions from landfills is expected to result in
climate co-benefits due to reductions of the methane component of LFG.
Methane is a potent GHG with a global warming potential (GWP) 28-36
times greater than CO2, which accounts for methane's
stronger absorption of infrared radiation per ton in the atmosphere,
but also its shorter lifetime (on the order of 12 years compared to
centuries or millennia for CO2).17 18 According
to the Intergovernmental Panel on Climate Change (IPCC) 5th Assessment
Report, methane is the second leading long-lived climate forcer after
CO2 globally.\19\
---------------------------------------------------------------------------

    \17\ IPCC, 2013: Climate Change 2013: The Physical Science
Basis. Contribution of Working Group I to the Fifth Assessment
Report of the Intergovernmental Panel on Climate Change [Stocker,
T.F., D. Qin, G.-K. Plattner, M. Tignor, S.K. Allen, J. Boschung, A.
Nauels, Y. Xia, V. Bex and P.M. Midgley (eds.)]. Cambridge
University Press, Cambridge, United Kingdom and New York, NY, USA.
    \18\ Note that this final uses a GWP value for methane of 25 for
CO2 equivalency calculations, consistent with the GHG
emissions inventories and the IPCC Fourth Assessment Report.
    \19\ IPCC, 2013: Climate Change 2013: The Physical Science
Basis. Contribution of Working Group I to the Fifth Assessment
Report of the Intergovernmental Panel on Climate Change [Stocker,
T.F., D. Qin, G.-K. Plattner, M. Tignor, S.K. Allen, J. Boschung, A.
Nauels, Y. Xia, V. Bex and P.M. Midgley (eds.)]. Cambridge
University Press, Cambridge, United Kingdom and New York, NY, USA.
---------------------------------------------------------------------------

    In 2009, based on a large body of robust and compelling scientific
evidence, the EPA Administrator issued an Endangerment Finding under
CAA section 202(a)(1).\20\ In the Endangerment Finding, the
Administrator found that the current, elevated concentrations of GHGs
in the atmosphere--already at levels unprecedented in human history--
may reasonably be anticipated to endanger public health and welfare of
current and future generations in the U.S. We summarize these adverse
effects on public health and welfare briefly here.
---------------------------------------------------------------------------

    \20\ ``Endangerment and Cause or Contribute Findings for
Greenhouse Gases Under Section 202(a) of the Clean Air Act,'' 74 FR
66496 (Dec. 15, 2009) (``Endangerment Finding'').
---------------------------------------------------------------------------

3. Public Health Impacts Detailed in the 2009 Endangerment Finding
    The 2009 Endangerment Finding documented that climate change caused
by human emissions of GHGs threatens the health of Americans. By
raising average temperatures, climate change increases the likelihood
of heat waves, which are associated with increased deaths and
illnesses. While climate change also increases the likelihood of
reductions in cold-related mortality, evidence indicates that the
increases in heat mortality will be larger than the decreases in cold
mortality in the United States. Compared to a future without climate
change, climate change is expected to increase ozone pollution over
broad areas of the U.S., including in the largest metropolitan areas
with the worst ozone problems, and thereby increase the risk of
morbidity and mortality. Climate change is also expected to cause more
intense hurricanes and more frequent and intense storms of other types
and heavy precipitation, with impacts on other areas of public health,
such as the potential for increased deaths, injuries, infectious and
waterborne diseases, and stress-related disorders. Children, the
elderly, and the poor are among the most vulnerable to these climate-
related health effects.
4. Public Welfare Impacts Detailed in the 2009 Endangerment Finding
    The 2009 Endangerment Finding documented that climate change
impacts touch nearly every aspect of public welfare. Among the multiple
threats caused by human emissions of GHGs, climate changes are expected
to place large areas of the country at serious risk of reduced water
supplies, increased water pollution, and increased occurrence of
extreme events such as floods and droughts. Coastal areas are expected
to face a multitude of increased risks, particularly from rising sea
level and increases in the severity of storms. These communities face
storm and flooding damage to property, or even loss of land due to
inundation, erosion, wetland submergence and habitat loss.
    Impacts of climate change on public welfare also include threats to
social and ecosystem services. Climate change is expected to result in
an increase in peak electricity demand. Extreme weather from climate
change threatens energy, transportation, and water resource
infrastructure. Climate change may also exacerbate ongoing
environmental pressures in certain settlements, particularly in Alaskan
indigenous communities, and is very likely to fundamentally rearrange
U.S. ecosystems over the 21st century. Though some benefits may balance
adverse effects on agriculture and forestry in the next few decades,
the body of evidence points towards increasing risks of net adverse
impacts on U.S. food production, agriculture and forest productivity as
temperature continues to rise. These impacts are global and may
exacerbate problems outside the U.S. that raise humanitarian, trade,
and national security issues for the U.S.
5. New Scientific Assessments
    In 2009, based on a large body of robust and compelling scientific
evidence, the EPA Administrator issued the Endangerment Finding under
CAA section 202(a)(1).\21\ In the Endangerment Finding, the
Administrator found that the current, elevated concentrations of GHGs
in the atmosphere--already at levels unprecedented in human history--
may reasonably be anticipated to endanger public health and welfare of
current and future generations in the U.S. The D.C. Circuit later
upheld the Endangerment Finding from all challenges. Coalition for
Responsible Regulation v. EPA, 684 F. 3d 102, 116-26 (D.C. Cir. 2012).
---------------------------------------------------------------------------

    \21\ ``Endangerment and Cause or Contribute Findings for
Greenhouse Gases Under Section 202(a) of the Clean Air Act,'' 74 FR
66496 (Dec. 15, 2009) (``Endangerment Finding'').
---------------------------------------------------------------------------

    Since the administrative record concerning the Endangerment Finding
closed following the EPA's 2010 Reconsideration Denial, the climate has
continued to change, with new records being set for a number of climate
indicators such as global average surface temperatures, Arctic sea ice
retreat, CO2 concentrations, and sea level rise.
Additionally, a number of major scientific assessments have been
released that improve understanding of the climate system and
strengthen the case that GHGs endanger public health and welfare both
for current and future generations. These assessments, from the
Intergovernmental Panel on Climate Change (IPCC), the U.S. Global
Change Research Program (USGCRP), and the National Research Council
(NRC), include: IPCC's 2012 Special Report on Managing the Risks of
Extreme Events and Disasters to Advance Climate Change Adaptation
(SREX) and the 2013-2014 Fifth Assessment Report (AR5), the USGCRP's
2014 National Climate Assessment, Climate Change Impacts in the United
States (NCA3), and the NRC's 2010 Ocean Acidification: A National
Strategy to Meet the Challenges of a Changing Ocean (Ocean
Acidification), 2011 Report on Climate Stabilization Targets:
Emissions, Concentrations, and Impacts over Decades to Millennia
(Climate Stabilization Targets), 2011 National Security Implications
for U.S. Naval Forces (National Security Implications), 2011
Understanding Earth's Deep Past: Lessons for Our Climate Future

(Understanding Earth's Deep Past), 2012 Sea Level Rise for the Coasts
of California, Oregon, and Washington: Past, Present, and Future, 2012
Climate and Social Stress: Implications for Security Analysis (Climate
and Social Stress), and 2013 Abrupt Impacts of Climate Change (Abrupt
Impacts) assessments.
    The conclusions of the recent scientific assessments confirm and
strengthen the science that supported the 2009 Endangerment Finding.
The NCA3 indicates that climate change ``threatens human health and
well-being in many ways, including impacts from increased extreme
weather events, wildfire, decreased air quality, threats to mental
health, and illnesses transmitted by food, water, and disease-carriers
such as mosquitoes and ticks.'' \22\ Most recently, the USGCRP released
a new assessment, ``The Impacts of Climate Change on Human Health in
the United States: A Scientific Assessment'' (also known as the USGCRP
Climate and Health Assessment). This assessment finds that ``climate
change impacts endanger our health'' and that in the United States we
have ``observed climate-related increases in our exposure to elevated
temperatures; more frequent, severe, or longer lasting extreme events;
diseases transmitted through food, water, or disease vectors such as
ticks and mosquitoes; and stresses to mental health and well-being.''
The assessment determines that ``[e]very American is vulnerable to the
health impacts associated with climate change.'' Climate warming will
also likely ``make it harder for any given regulatory approach to
reduce ground-level ozone pollution'', and, unless offset by reductions
of ozone precursors, it is likely that ``climate-driven increases in
ozone will cause premature deaths, hospital visits, lost school days,
and acute respiratory symptoms.'' \23\
---------------------------------------------------------------------------

    \22\ USGCRP, Third National Climate Assessment, p. 221.
    \23\ See also Kleeman, M.J., S.-H. Chen, and R.A. Harley. 2010.
Climate change impact on air quality in California: Report to the
California Air Resources Board. http://www.arb.ca.gov/research/apr/past/04-349.pdf.
---------------------------------------------------------------------------

    Assessments state that certain populations are particularly
vulnerable to climate change. The USGCRP Climate and Health Assessment
assesses several disproportionately vulnerable populations, including
those with low income, some communities of color, immigrant groups,
indigenous peoples, pregnant women, vulnerable occupational groups,
persons with disabilities, and persons with preexisting or chronic
medical conditions. The Climate and Health Assessment also concludes
that children's unique physiology and developing bodies contribute to
making them particularly vulnerable to climate change. Children also
have unique behaviors and exposure pathways that could increase their
exposure to environmental stressors, like contaminants in dust or
extreme heat events. Impacts from climate change on children are likely
from heat waves, air pollution, infectious and waterborne illnesses,
disruptions in food safety and security, and mental health effects
resulting from extreme weather events. For example, climate change can
disrupt food safety and security by significantly reducing food
quality, availability and access. Children are more susceptible to this
disruption because nutrition is important during critical windows of
development and growth. Older people are at much higher risk of
mortality during extreme heat events and pre-existing health conditions
also make older adults susceptible to cardiac and respiratory impacts
of air pollution and to more severe consequences from infectious and
waterborne diseases. Limited mobility among older adults can also
increase health risks associated with extreme weather and floods.
    The new assessments also confirm and strengthen the science that
supported the 2009 Endangerment Finding. The NRC assessment
Understanding Earth's Deep Past stated that ``[b]y the end of this
century, without a reduction in emissions, atmospheric CO2
is projected to increase to levels that Earth has not experienced for
more than 30 million years.'' In fact, that assessment stated that
``the magnitude and rate of the present GHG increase place the climate
system in what could be one of the most severe increases in radiative
forcing of the global climate system in Earth history.'' \24\ Because
of these unprecedented changes in atmospheric concentrations, several
assessments state that we may be approaching critical, poorly
understood thresholds. The NRC Abrupt Impacts report analyzed the
potential for abrupt climate change in the physical climate system and
abrupt impacts of ongoing changes that, when thresholds are crossed,
could cause abrupt impacts for society and ecosystems. The report
considered destabilization of the West Antarctic Ice Sheet (which could
cause 3-4 m of potential sea level rise) as an abrupt climate impact
with unknown but probably low probability of occurring this century.
The report categorized a decrease in ocean oxygen content (with
attendant threats to aerobic marine life); increase in intensity,
frequency, and duration of heat waves; and increase in frequency and
intensity of extreme precipitation events (droughts, floods,
hurricanes, and major storms) as climate impacts with moderate risk of
an abrupt change within this century. The NRC Abrupt Impacts report
also analyzed the threat of rapid state changes in ecosystems and
species extinctions as examples of an irreversible impact that is
expected to be exacerbated by climate change. Species at most risk
include those whose migration potential is limited, whether because
they live on mountaintops or fragmented habitats with barriers to
movement, or because climatic conditions are changing more rapidly than
the species can move or adapt. While some of these abrupt impacts may
be of low or moderate probability in this century, the probability for
a significant change in many of these processes after 2100 was judged
to be higher, with severe impacts likely should the abrupt change
occur. Future temperature changes will be influenced by what emissions
path the world follows. In its high emission scenario, the IPCC AR5
projects that global temperatures by the end of the century will likely
be 2.6 [deg]C to 4.8 [deg]C (4.7 to 8.6 [deg]F) warmer than today.
There is very high confidence that temperatures on land and in the
Arctic will warm even faster than the global average. However,
according to the NCA3, significant reductions in emissions would lead
to noticeably less future warming beyond mid-century, and therefore
less impact to public health and welfare. According to the NCA3,
regions closer to the poles are projected to receive more
precipitation, while the dry subtropics expand (colloquially, this has
been summarized as wet areas getting wet and dry regions getting
drier), while ``[t]he widespread trend of increasing heavy downpours is
expected to continue, with precipitation becoming less frequent but
more intense.'' Meanwhile, the NRC Climate Stabilization Targets
assessment found that the area burned by wildfire in parts of western
North America is expected to grow by 2 to 4 times for 1 [deg]C (1.8
[deg]F) of warming. The NCA also found that ``[e]xtrapolation of the
present observed trend suggests an essentially ice-free Arctic in
summer before mid-century.'' Retreating snow and ice, and emissions of
carbon dioxide and methane released from thawing permafrost, are very
likely to amplify future warming.
---------------------------------------------------------------------------

    \24\ National Research Council, Understanding Earth's Deep Past,
p. 138.
---------------------------------------------------------------------------

    Since the 2009 Endangerment Finding, the IPCC AR5, the USGCRP

NCA3, and three of the new NRC assessments provide estimates of
projected global average sea level rise. These estimates, while not
always directly comparable as they assume different emissions scenarios
and baselines, are at least 40 percent larger than, and in some cases
more than twice as large as, the projected rise estimated in the IPCC
AR4 assessment, which was referred to in the 2009 Endangerment Finding.
The NRC Sea Level Rise assessment projects a global average sea level
rise of 0.5 to 1.4 meters by 2100. The NRC National Security
Implications assessment suggests that ``the Department of the Navy
should expect roughly 0.4 to 2 meters global average sea-level rise by
2100.'' The NRC Climate Stabilization Targets assessment states that a
global average temperature increase of 3 [deg]C will lead to a global
average sea level rise of 0.5 to 1 meter by 2100. These NRC and IPCC
assessments continue to recognize and characterize the uncertainty
inherent in accounting for melting ice sheets in sea level rise
projections.
    In addition to future impacts, the NCA3 emphasizes that climate
change driven by human emissions of GHGs is already happening now and
it is happening in the U.S. According to the IPCC AR5 and the NCA3,
there are a number of climate-related changes that have been observed
recently, and these changes are projected to accelerate in the future:

     The planet warmed about 0.85 [deg]C (1.5 [deg]F) from
1880 to 2012. It is extremely likely (>95 percent probability) that
human influence was the dominant cause of the observed warming since
the mid-20th century, and likely (>66 percent probability) that
human influence has more than doubled the probability of occurrence
of heat waves in some locations. In the Northern Hemisphere, the
last 30 years were likely the warmest 30 year period of the last
1400 years.
     Global sea levels rose 0.19 m (7.5 inches) from 1901 to
2010. Contributing to this rise was the warming of the oceans and
melting of land ice. It is likely that 275 gigatons per year of ice
melted from land glaciers (not including ice sheets) since 1993, and
that the rate of loss of ice from the Greenland and Antarctic ice
sheets increased substantially in recent years, to 215 gigatons per
year and 147 gigatons per year respectively since 2002. For context,
360 gigatons of ice melt is sufficient to cause global sea levels to
rise 1 mm.
     Annual mean Arctic sea ice has been declining at 3.5 to
4.1 percent per decade, and Northern Hemisphere snow cover extent
has decreased at about 1.6 percent per decade for March and 11.7
percent per decade for June.
     Permafrost temperatures have increased in most regions
since the 1980s, by up to 3 [deg]C (5.4 [deg]F) in parts of Northern
Alaska.
     Winter storm frequency and intensity have both
increased in the Northern Hemisphere. The NCA3 states that the
increases in the severity or frequency of some types of extreme
weather and climate events in recent decades can affect energy
production and delivery, causing supply disruptions, and compromise
other essential infrastructure such as water and transportation
systems.

    In addition to the changes documented in the assessment literature,
there have been other climate milestones of note. According to the
National Oceanic and Atmospheric Administration (NOAA), methane
concentrations in 2014 were about 1,823 parts per billion, 150 percent
higher than concentrations were in 1750. After a few years of nearly
stable concentrations from 1999 to 2006, methane concentrations have
resumed increasing at about 5 parts per billion per year.\25\
Concentrations today are likely higher than they have been for at least
the past 800,000 years.\26\ Arctic sea ice has continued to decline,
with September of 2012 marking the record low in terms of Arctic sea
ice extent, 40 percent below the 1979-2000 median. Sea level has
continued to rise at a rate of 3.2 mm per year (1.3 inches/decade)
since satellite observations started in 1993, more than twice the
average rate of rise in the 20th century prior to 1993.\27\ And 2015
was the warmest year globally in the modern global surface temperature
record, going back to 1880, breaking the record previously held by
2014; this now means that the last 15 years have been 15 of the 16
warmest years on record.\28\
---------------------------------------------------------------------------

    \25\ Ed Dlugokencky, NOAA/ESRL (www.esrl.noaa.gov/gmd/ccgg/trends_ch4/).
    \26\ U.S. Environmental Protection Agency. 2014. Climate change
indicators in the United States,2014. Third edition. EPA 430-R-14-
004. www.epa.gov/climatechange/indicators.
    \27\ Blunden, J., and D.S. Arndt, Eds., 2015: State of the
Climate in 2014. Bull. Amer. Meteor. Soc., 96 (7), S1-S267.
    \28\ http://www.ncdc.noaa.gov/sotc/global/201513.
---------------------------------------------------------------------------

    These assessments and observed changes raise concerns that reducing
emissions of GHGs across the globe is necessary in order to avoid the
worst impacts of climate change, and underscore the urgency of reducing
emissions now. In 2011 the NRC Committee on America's Climate Choices
listed a number of reasons ``why it is imprudent to delay actions that
at least begin the process of substantially reducing emissions.'' \29\
For example, they stated:
---------------------------------------------------------------------------

    \29\ NRC, 2011: America's Climate Choices, The National
Academies Press, p. 2.

     The faster emissions are reduced, the lower the risks
posed by climate change. Delays in reducing emissions could commit
the planet to a wide range of adverse impacts, especially if the
sensitivity of the climate to GHGs is on the higher end of the
estimated range.
     Waiting for unacceptable impacts to occur before taking
action is imprudent because the effects of GHG emissions do not
fully manifest themselves for decades and, once manifested, many of
these changes will persist for hundreds or even thousands of years.
     In the committee's judgment, the risks associated with
doing business as usual are a much greater concern than the risks
associated with engaging in strong response efforts.

Overview of Climate Change Impacts in the United States

    The NCA3 assessed the climate impacts in eight regions of the U.S.,
noting that changes in physical climate parameters such as
temperatures, precipitation, and sea ice retreat were already having
impacts on forests, water supplies, ecosystems, flooding, heat waves,
and air quality. The U.S. average temperatures have similarly increased
by 1.3 to 1.9 degrees F since 1895, with most of that increase
occurring since 1970, and the most recent decade was the U.S.'s hottest
as well as the world's hottest. Moreover, the NCA3 found that future
warming is projected to be much larger than recent observed variations
in temperature, with 2 to 4 degrees F warming expected in most areas of
the U.S. over the next few decades, and up to 10 degrees F possible by
the end of the century assuming continued increases in emissions.
Extreme heat events will continue to become more common, and extreme
cold less common. Additionally, precipitation is considered likely to
increase in the northern states, decrease in the southern states, and
with the heaviest precipitation events projected to increase
everywhere.
    In the Northeast, temperatures increased almost 2 [deg]F from 1895
to 2011, precipitation increased by about 5 inches (10 percent), and
sea level rise of about a foot has led to an increase in coastal
flooding. In the future, if emissions continue to increase, the
Northeast is projected to experience 4.5 to 10 [deg]F of warming by the
2080s. This is expected to lead to more heat waves, coastal and river
flooding, and intense precipitation events. Sea levels in the Northeast
are expected to increase faster than the global average because of
subsidence, and models suggest changing ocean currents may further
increase the rate of sea level rise.
    In the Southeast, average annual temperature during the last
century cycled between warm and cool periods. A warm peak occurred
during the 1930s

and 1940s followed by a cool period and temperatures then increased
again from 1970 to the present by an average of 2 [deg]F. Louisiana has
already lost 1,880 square miles of land in the last 80 years due to sea
level rise and other contributing factors. The Southeast is
exceptionally vulnerable to sea level rise, extreme heat events,
hurricanes, and decreased water availability. Major risks of further
warming include significant increases in the number of hot days (95
[deg]F or above) and decreases in freezing events, as well as
exacerbated ground level ozone in urban areas. Projections suggest that
there may be fewer hurricanes in the Atlantic in the future, but they
will be more intense, with more Category 4 and 5 storms. The NCA
identified New Orleans, Miami, Tampa, Charleston, and Virginia Beach as
cities at particular risk of flooding.
    In the Northwest, temperatures increased by about 1.3 [deg]F
between 1895 and 2011. Snowpack in the Northwest is an important
freshwater source for the region. More precipitation falling as rain
instead of snow has reduced the snowpack, and warmer springs have
corresponded to earlier snowpack melting and reduced stream flows
during summer months. Drier conditions have increased the extent of
wildfires in the region. Average annual temperatures are projected to
increase by 3.3 [deg]F to 9.7 [deg]F by the end of the century
(depending on future global GHG emissions), with the greatest warming
is expected during the summer. Continued increases in global GHG
emissions are projected to result in up to a 30 percent decrease in
summer precipitation. Warmer waters are expected to increase disease
and mortality in important fish species, including Chinook and sockeye
salmon.
    In Alaska, temperatures have changed faster than anywhere else in
the U.S. Annual temperatures increased by about 3 [deg]F in the past 60
years. Warming in the winter has been even greater, rising by an
average of 6 [deg]F. Glaciers in Alaska are melting at some of the
fastest rates on Earth. Permafrost soils are also warming and beginning
to thaw. Drier conditions had already contributed to more large
wildfires in the 10 years prior to the NCA3 than in any previous decade
since the 1940s, when recordkeeping began, and subsequent years have
seen even more wildfires. By the end of this century, continued
increases in GHG emissions are expected to increase temperatures by 10
to 12 [deg]F in the northernmost parts of Alaska, by 8 to 10 [deg]F in
the interior, and by 6 to 8 [deg]F across the rest of the state. These
increases will exacerbate ongoing arctic sea ice loss, glacial melt,
permafrost thaw and increased wildfire, and threaten humans,
ecosystems, and infrastructure.
    In the Southwest, temperatures are now about 2 [deg]F higher than
the past century, and are already the warmest that region has
experienced in at least 600 years. The NCA notes that there is evidence
that climate-change induced warming on top of recent drought has
influenced tree mortality, wildfire frequency and area, and forest
insect outbreaks. At the time of publication of the NCA, even before
the last 2 years of extreme drought in California, tree ring data was
already indicating that the region might be experiencing its driest
period in 800 years. The Southwest is projected to warm an additional
5.5 to 9.5 [deg]F over the next century if emissions continue to
increase. Winter snowpack in the Southwest is projected to decline
(consistent with recent record lows), reducing the reliability of
surface water supplies for cities, agriculture, cooling for power
plants, and ecosystems. Sea level rise along the California coast is
projected to worsen coastal erosion, increase flooding risk for coastal
highways, bridges, and low-lying airports, and pose a threat to
groundwater supplies in coastal cities. Also, ``[t]he combination of a
longer frost-free season, less frequent cold air outbreaks, and more
frequent heat waves accelerates crop ripening and maturity, reduces
yields of corn, tree fruit, and wine grapes, stresses livestock, and
increases agricultural water consumption.'' Increased drought, higher
temperatures, and bark beetle outbreaks are likely to contribute to
continued increases in wildfires.
    The rate of warming in the Midwest has markedly accelerated over
the past few decades. Temperatures rose by more than 1.5 [deg]F from
1900 to 2010, but between 1980 and 2010 the rate of warming was three
times faster than from 1900 through 2010. Precipitation generally
increased over the last century, with much of the increase driven by
intensification of the heaviest rainfalls. Several types of extreme
weather events in the Midwest (e.g., heat waves and flooding) have
already increased in frequency and/or intensity due to climate change.
In the future, if emissions continue increasing, the Midwest is
expected to experience 5.6 to 8.5 [deg]F of warming by the 2080s,
leading to more heat waves. Specific vulnerabilities highlighted by the
NCA include long-term decreases in agricultural productivity, changes
in the composition of the region's forests, increased public health
threats from heat waves and degraded air and water quality, negative
impacts on transportation and other infrastructure associated with
extreme rainfall events and flooding, and risks to the Great Lakes
including shifts in invasive species, increases in harmful algal
blooms, and declining beach health.
    High temperatures (more than 100 [deg]F in the Southern Plains and
more than 95 [deg]F in the Northern Plains) are projected to occur much
more frequently by mid-century. Increases in extreme heat will increase
heat stress for residents, energy demand for air conditioning, and
water losses. In Hawaii, other Pacific islands, and the Caribbean,
rising air and ocean temperatures, shifting rainfall patterns, changing
frequencies and intensities of storms and drought, decreasing base flow
in streams, rising sea levels, and changing ocean chemistry will affect
ecosystems on land and in the oceans, as well as local communities,
livelihoods, and cultures. Low islands are particularly at risk.
    In Hawaii and the Pacific islands, ``[w]armer oceans are leading to
increased coral bleaching events and disease outbreaks in coral reefs,
as well as changed distribution patterns of tuna fisheries. Ocean
acidification will reduce coral growth and health. Warming and
acidification, combined with existing stresses, will strongly affect
coral reef fish communities.'' For Hawaii and the Pacific islands,
future sea surface temperatures are projected to increase 2.3 [deg]F by
2055 and 4.7 [deg]F by 2090 under a scenario that assumes continued
increases in emissions.
    Methane Specific Impacts. Methane is also a precursor to ground-
level ozone, which can cause a number of harmful effects on public
health and the environment. Additionally, ozone is a short-lived
climate forcer that contributes to global warming. In remote areas,
methane is an important precursor to tropospheric ozone formation.\30\
Almost half of the global annual mean ozone increase since
preindustrial times is believed to be due to anthropogenic methane.\31\
Projections of future emissions also indicate that methane is likely to
be a key contributor to ozone concentrations in the future.\32\ Unlike
nitrogen oxide (NOX) and VOC, which affect ozone
concentrations regionally and at hourly time scales, methane emissions
affect ozone concentrations globally and on decadal

time scales given methane's relatively long atmospheric lifetime
compared to these other ozone precursors.\33\ Reducing methane
emissions, therefore, may contribute to efforts to reduce global
background ozone concentrations that contribute to the incidence of
ozone-related health effects.34 35 36 These benefits are
global and occur in both urban and rural areas.
---------------------------------------------------------------------------

    \30\ U.S. EPA. 2013. ``Integrated Science Assessment for Ozone
and Related Photochemical Oxidants (Final Report).'' EPA-600-R-10-
076F. National Center for Environmental Assessment--RTP Division.
Available at http://www.epa.gov/ncea/isa/.
    \31\ Ibid.
    \32\ Ibid.
    \33\ Ibid.
    \34\ West, J.J., Fiore, A.M. 2005. ``Management of tropospheric
ozone by reducing methane emissions.'' Environ. Sci. Technol.
39:4685-4691.
    \35\ Anenberg, S.C., et al. 2009. ``Intercontinental impacts of
ozone pollution on human mortality,'' Environ. Sci. & Technol. 43:
6482-6487.
    \36\ Sarofim, M.C., Waldhoff, S.T., Anenberg, S.C. 2015.
``Valuing the Ozone-Related Health Benefits of Methane Emission
Controls,'' Environ. Resource Econ. DOI 10.1007/s10640-015-9937-6.
---------------------------------------------------------------------------

C. What is the EPA's authority for reviewing the NSPS?

    Section 111 of the Clean Air Act (CAA) requires the EPA
Administrator to list categories of stationary sources that in the
Administrator's judgment cause or contribute significantly to air
pollution that may reasonably be anticipated to endanger public health
or welfare. 42 U.S.C. 7411(b)(1)(A). The EPA must then issue
performance standards for new (and modified or reconstructed) sources
in each source category. 42 U.S.C. 7411(b)(1)(B). These standards are
referred to as new source performance standards or NSPS. The EPA has
the authority to define the scope of the source categories, determine
the pollutants for which standards should be developed, set the
emission level of the standards, and distinguish among classes, type
and sizes within categories in establishing the standards. 42 U.S.C.
7411(b).
    On March 12, 1996 (61 FR 9905), under the authority of CAA section
111(b)(1)(A), the EPA added the MSW landfills source category to the
priority list in 40 CFR 60.16 because, in the judgment of the
Administrator, the source category contributes significantly to air
pollution that may reasonably be anticipated to endanger public health
and welfare. In that same notice, the EPA promulgated new source
performance standards, which apply to new (and modified or
reconstructed) landfills under the authority of CAA section
111(b)(1)(B), and emission guidelines, which apply to existing
landfills, under the authority of CAA section 111(d). In the March 12,
1996 notice, the EPA defined the MSW landfills source category,
identified municipal solid waste landfill emissions (commonly referred
to as landfill gas) as the pollutant for which standards should be
developed, identified which landfills would be covered, and determined
the applicability threshold and emission level of the standards.
    CAA section 111(a)(1) (42 U.S.C. 7411(a)(1)) provides that
standards of performance are to ``reflect the degree of emission
limitation achievable through the application of the best system of
emission limitation achievable through the application of the best
system of emission reduction which (taking into account the cost of
achieving such reduction and any nonair quality health environmental
impact and energy requirements) the Administrator determines has been
adequately demonstrated.'' We refer to this level of control as the
best system of emission reduction or BSER. When promulgated in 1996,
BSER for MSW landfills was determined to be a well-designed and well-
operated LFG collection and control system with a control device
capable of reducing NMOC by 98 percent by weight. NMOC was established
as a surrogate for LFG in the final rule.
    The CAA also requires the EPA to review the NSPS at least every 8
years to determine if the level of control that was previously
established remains appropriate. Specifically, CAA section 111(b)(1)(B)
(42 U.S.C. 7411(b)(1)(B)) requires the EPA to ``at least every 8 years
review and, if appropriate, revise'' standards of performance. The
Administrator need not review a standard, however, if the
``Administrator determines that such review is not appropriate in light
of readily available information on the efficacy'' of the standard.
While not required to do so, the EPA has authority to revise an NSPS to
add emission limits for pollutants or emission sources not currently
concurrent with its review of the NSPS (77 FR 49494, August 16, 2012).
    In determining BSER, we typically conduct a review that identifies
what emission reduction systems exist and how much they reduce air
pollution in practice. Next, for each control system identified, we
evaluate its costs, energy requirements, and any nonair quality health
and environmental impacts. Based on our evaluation, we determine BSER
for each pollutant to be regulated and establish an appropriate
standard of performance based on the identified BSER. The resultant
standard is usually expressed either as a numerical emissions limit,
e.g., ppm or pounds per million British thermal unit (lb/MMBtu), or a
percent reduction requirement. Although the standards are based on the
identified BSER, the EPA may not require the use of a particular
technology to comply with a performance standard unless the
Administrator determines that it is not feasible to prescribe or
enforce a standard of performance. (CAA 111(b)(5), 42 U.S.C.
7411(b)(5).) Thus, except in rare circumstances, sources remain free to
select any control measures that will meet the requirements of the
standard(s). Upon promulgation, an NSPS becomes a national standard
with which all new, reconstructed, and modified sources must comply.
(CAA 111(e), 42 U.S.C. 7411(e).)

D. What is the purpose and scope of this action?

    The purpose of this action is to (1) Present the results of the
EPA's review of the MSW landfills NSPS, (2) finalize revisions to the
NSPS based on that review, and (3) resolve or clarify several
implementation issues that were addressed in prior proposed amendments
published on May 23, 2002 (67 FR 36475) and September 8, 2006 (71 FR
53271) as they apply to new, modified, or reconstructed sources. The
final revisions appear in 40 CFR part 60, subpart XXX.\37\ Although the
EPA is not required to respond to comments received on the July 17,
2014, ANPRM (79 FR 41772) for the MSW landfills Emission Guidelines or
comments it received on the concurrent proposal for revised Emission
Guidelines for existing MSW landfills, in this document, the EPA is
summarizing several comments it received to provide a framework and
support the rationale for the final revisions to the NSPS.
---------------------------------------------------------------------------

    \37\ Rather than merely updating 40 CFR part 60, subpart WWW,
the existing NSPS, the EPA has determined that the most appropriate
way to proceed is to establish a new subpart that includes both the
verbatim restatement of certain provisions in the existing NSPS and
revisions to, or the addition of, other provisions.
---------------------------------------------------------------------------

E. How would the changes in applicability affect sources currently
subject to subparts Cc and WWW?

    Landfills currently subject to 40 CFR part 60, subparts Cc and WWW
are considered ``existing'' with the promulgation of this new NSPS
subpart XXX and are not affected by any changes to the NSPS resulting
from this review. Each MSW landfill for which construction,
modification, or reconstruction commenced on or before July 17, 2014,
the date of proposal of the standard for new landfill under subpart
XXX, is an existing source. Under section 111, a source is either new,
i.e., construction, modification, or reconstruction commenced after a
proposed NSPS is published in the Federal Register (CAA section
111(a)(1))

or existing, i.e., any source other than a new source (CAA section
111(a)(6)). Since the revised NSPS apply to new (and modified or
reconstructed) sources, any source that is not subject to subpart XXX
will be subject to the revised Emission Guidelines found in 40 CFR part
60, subpart Cf. Any existing MSW landfill that modifies or reconstructs
after July 17, 2014 would become a new source subject to the NSPS
subpart XXX.

IV. Summary of the Final NSPS

A. What are the control requirements?

1. Design Capacity and Emissions Thresholds
    The revised NSPS retain the current design capacity threshold of
2.5 million Mg and 2.5 million m\3\, but reduce the NMOC emission
threshold for the installation and removal of a GCCS from 50 Mg/yr to
34 Mg/yr for landfills that commence construction, reconstruction, or
modification after July 17, 2014. An MSW landfill that exceeds the
design capacity threshold must install and start up a GCCS within 30
months after LFG emissions reach or exceed an NMOC level of 34 Mg/yr
NMOC. The owner or operator of a landfill may control the gas by
routing it to a non-enclosed flare, an enclosed combustion device, or a
treatment system that processes the collected gas for subsequent sale
or beneficial use.
2. Tier 4
    The current NSPS (40 CFR part 60, subpart WWW) provides that owners
or operators determine whether the landfill has exceeded the NMOC
emissions threshold using one of three available modeling approaches,
known as Tiers 1, 2 and 3. The EPA is finalizing in subpart XXX an
additional optional methodology based on site-specific surface methane
emissions to determine when a landfill must install and operate a GCCS.
This alternative emission threshold methodology, referred to as ``Tier
4,'' is based on SEM and demonstrates that surface methane emissions
are below a specific threshold. The Tier 4 SEM demonstration allows
certain landfills that exceed modeled NMOC emission rate thresholds
using Tier 1 or 2 to demonstrate that site-specific surface methane
emissions are below a surface concentration threshold. A landfill that
can demonstrate that surface emissions are below 500 ppm for four
consecutive quarters does not trigger the requirement to install a GCCS
even if Tier 1, 2, or 3 calculations indicate that the 34 Mg/yr
threshold has been exceeded. Owners or operators continue to keep
detailed records of each quarterly monitoring demonstration and must
submit a Tier 4 surface emissions report annually. Upon a surface
emissions reading of greater than 500 ppm methane, the landfill must
submit a GCCS design plan and install and operate a GCCS.
    Tier 4 is based on the results of quarterly site-specific methane
emissions monitoring of the perimeter of the landfill and entire
surface of the landfill along a pattern that traverses the landfill at
30-meter (98-ft) intervals, in addition to monitoring areas where
visual observations may indicate elevated concentrations of LFG, such
as distressed vegetation and cracks or seeps in the cover and all cover
penetrations. If the landfill opts to use Tier 4 and there is any
measured concentration of methane of 500 ppm or greater from the
surface of the landfill, the owner or operator must install a GCCS, and
the landfill cannot return to Tier 1, 2, or 3 modeling to demonstrate
that emissions are below the NMOC threshold.
    Tier 4 is allowed only if the landfill owner or operator can
demonstrate that NMOC emissions are greater than or equal to 34 Mg/yr,
but less than 50 Mg/yr using Tier 1 or Tier 2. If both Tier 1 and Tier
2 indicate NMOC emissions of 50 Mg/yr or greater, Tier 4 cannot be used
(a landfill need not model emissions under Tier 3 before using Tier 4).
In order to verify that the landfill is eligible for Tier 4, the EPA is
finalizing a provision to require landfill owners or operators that
choose to use Tier 4 to continue to conduct Tier 1 and Tier 2 NMOC
emission rate calculations and report results in the annual report.
    In addition, the EPA is finalizing specific requirements for the
use of Tier 4 for emission threshold determinations related to wind
speed. Since accurate measurements can be compromised in even
moderately windy conditions, the EPA is requiring the owner or operator
to use a wind barrier, similar to a funnel or other device, to minimize
surface air turbulence when onsite wind speed exceeds the limits in the
rule. Thus, when a wind barrier is used, the final rule allows the Tier
4 surface emissions demonstration to proceed when the average on-site
wind speed exceeds 4 mph, or gusts exceed 10 mph. Tier 4 measurements
cannot be conducted if the average wind speed exceeds 25 mph. Although
we are aware of the use of wind barriers in the field, the EPA intends
to provide additional guidance on their use. In addition, the owner or
operator must take digital photographs of the instrument setup,
including the wind barrier. The photographs must be time and date-
stamped and taken at the first sampling location prior to sampling and
at the last sampling location after sampling at the end of each
sampling day, for the duration of the Tier 4 monitoring demonstration.
The owner or operator must maintain those photographs per the
recordkeeping requirements. Wind speed must be measured with an on-site
anemometer with a continuous recorder and data logger for the entire
duration of the monitoring event. The average wind speed must be
determined at 5-minute intervals. The gust must be determined at 3-
second intervals. Further, when taking surface measurements, the
sampling probe must be held no more than 5 centimeters above the
landfill surface (e.g., using a mechanical device such as a wheel on a
pole).
    The EPA is also limiting the use of Tier 4 at landfills with a GCCS
installed. In order for a landfill with an operational GCCS to qualify
for Tier 4, the GCCS must have operated for at least 75 percent of the
12 months prior to initiating Tier 4 testing. The EPA is finalizing
reporting and recordkeeping requirements for the annual operating hours
of destruction devices in order to verify that a landfill with a GCCS
installed and opting for Tier 4 meets the GCCS criteria for having
operated the system.
    The EPA is also finalizing reporting and recordkeeping requirements
to improve the transparency of SEM testing. To ensure that a GCCS is
installed in a timely manner, the EPA is requiring a GCCS to be
installed and operated within 30 months of the most recent NMOC
emission rate report in which the calculated NMOC emission rate equals
or exceeds 34 Mg/yr according to Tier 2, once there is any measured
concentration of methane of 500 ppm or greater from the surface of the
landfill. To improve the transparency of SEM testing, landfill owners
or operators must notify the delegated authority 30 days prior to
conducting Tier 4 tests and maintain records of all SEM monitoring data
and calibrations.
3. Criteria for Removing GCCS
    Landfill emissions increase as waste is added to a landfill, but
decline over time; as waste decays, a landfill produces less and less
methane and other pollutants. In the proposed revisions to the NSPS (79
FR 41811), the EPA requested comment on whether the three criteria for
control device removal in 40 CFR part 60, subpart WWW were appropriate
for proposed 40 CFR part 60, subpart XXX, and whether alternative
criteria such as consecutive

quarterly measurements below a surface emission threshold should also
be considered. Additionally, in the proposed revisions to the Emission
Guidelines (80 FR 52112), the EPA recognized that many open landfills
subject to control requirements contain inactive areas that have
experienced declining LFG flows. The EPA is finalizing criteria for
determining when it is appropriate to cap, remove, or decommission a
portion of the GCCS. The criteria for capping, removing, or
decommissioning the GCCS are: (1) The landfill is closed, (2) the
calculated NMOC emission rate at the landfill is less than 34 Mg/yr on
three successive test dates, and (3) the GCCS has operated for at least
15 years or the landfill owner or operator can demonstrate that the
GCCS will be unable to operate for 15 years due to declining gas flows.
4. Excluding Non-Productive Areas From Control
    In the proposed revisions to the NSPS (79 FR 41817), the EPA
recognized that there are situations in which the quantity of gas
production has greatly declined in separate closed areas of some
landfills, and the methane content has fallen such that the area is
producing insufficient gas to properly operate a GCCS and control
device. Thus, the EPA is finalizing a provision that allows the use of
actual flow data when estimating NMOC emissions for the purposes of
excluding low- or non-productive areas of the landfill from control. To
determine whether NMOC emissions from non-productive areas of the
landfill are less than 1 percent of the total landfill NMOC emissions
(and hence controls are not required), subpart WWW relies on modeled
(calculated) NMOC rates (see 40 CFR 60.759(a)(3)(ii)). To refine the
measurements of these non-productive areas, subpart XXX (40 CFR
60.769(a)(3)(ii)) allows owners or operators of landfills with
physically separated, closed areas to either model NMOC emission rates,
or determine the flow rate of LFG using actual measurements, to
determine NMOC emissions. Using actual flow measurements yields a more
precise measurement of NMOC emissions for purposes of demonstrating the
closed area represents less than 1 percent of the landfill's total NMOC
emissions. The NSPS has historically allowed owners or operators to
exclude from control areas that are non-productive. In the final rule,
the retained the 1 percent criteria level, rather than raising it, to
prevent landfills from excluding areas from control unless emissions
were very low. But, to help owners or operators demonstrate that a non-
productive area may be excluded from control, the final rule allows the
owner or operator to use site-specific flow measurements to determine
NMOC emissions.
5. Landfill Gas Treatment
    The EPA is finalizing two provisions related to LFG treatment.
First, the EPA is clarifying that the use of treated LFG is not limited
to use as a fuel for a stationary combustion device but also allows
other beneficial uses such as vehicle fuel, production of high-Btu gas
for pipeline injection, and use as a raw material in a chemical
manufacturing process. Second, the EPA is defining ``treated landfill
gas'' as LFG processed in a treatment system meeting the requirements
in 40 CFR part 60, subpart XXX and defining ``treatment system'' as a
system that filters, de-waters, and compresses LFG for sale or
beneficial use. Owners or operators must develop a site-specific
treatment system monitoring plan that includes monitoring parameters
addressing all three elements of treatment (filtration, de-watering,
and compression) to ensure the treatment system is operating properly
for each intended end use of the treated LFG. They also must keep
records that demonstrate that such parameters effectively monitor
filtration, de-watering, and compression system performance necessary
for each end use of the treated LFG. The treatment system monitoring
plan must be submitted as part of the landfill's Title V permit
application. The permitting authority will review the permit
application, including the treatment system monitoring plan, as part of
the general permitting process. The treatment system monitoring
parameters would be included in the permit as applicable requirements
and thus become enforceable conditions (i.e., the landfill monitors the
treatment system monitoring parameters and maintains them in the
specified range).

B. What are the monitoring, recordkeeping, and reporting requirements?

1. Wellhead Monitoring
    The operational standard, corrective action, and corresponding
recordkeeping and reporting remain for temperature and maintaining
negative pressure at the wellhead. The EPA is removing the operational
standards (i.e., the requirement to meet operating limits) for
nitrogen/oxygen at the wellheads. Thus, the EPA is removing the
corresponding requirement to take corrective action for exceedances of
nitrogen/oxygen at the wellheads. These adjustments to the wellhead
monitoring parameters apply to all landfills. Although landfill owners
or operators are not required to take corrective action based on
exceedances of nitrogen/oxygen levels at wellheads, they are required
to monitor and maintain records of nitrogen/oxygen levels at wellheads
on a monthly basis to inform any necessary adjustments to the GCCS and
must maintain records of all monthly readings. The landfill owner or
operator must make these records available to the Administrator (EPA
Administrator or administrator of a state air pollution control agency
or his or her designee) upon request.
2. Surface Monitoring
    The EPA is finalizing the proposed requirement to monitor all
surface penetrations. Landfills must conduct SEM at all cover
penetrations and openings within the area of the landfill where waste
has been placed and a GCCS is required to be in place and operating
according to the operational standards in 40 CFR part 60, subpart XXX.
Specifically, landfill owners or operators must conduct surface
monitoring on a quarterly basis around the entire perimeter of the
collection area, and along a pattern that traverses the landfill at no
more than 30-meter intervals, at all cover penetrations, and where
visual observations may indicate elevated concentrations of LFG, such
as distressed vegetation and cracks or seeps in the cover. Cover
penetrations include wellheads, but do not include items such as survey
stakes, fencing or litter fencing, flags, signs, trees, and utility
poles.
3. Corrective Action
    The owner or operator must measure the LFG temperature at the
wellhead and gauge pressure in the gas collection header applied to
each individual well on a monthly basis. If there is an exceedance
(i.e., LFG temperature of 55 degrees Celsius (131 degrees Fahrenheit)
or positive pressure), the owner or operator must initiate corrective
action within 5 days. If the temperature exceedance or negative
pressure cannot be achieved within 15 days, then the owner or operator
must determine the appropriate corrective action by conducting a root
cause analysis and correct the exceedance as soon as practicable, but
no later than 60 days after the first measurement of the temperature
exceedance or positive pressure. For corrective action that takes
longer than 60 days to fully implement, the owner or operator must also
conduct a corrective action analysis and develop

an implementation schedule for the corrective action that does not
exceed 120 days. The owner or operator must also notify the
Administrator of any corrective action exceeding 60 days within 75 days
and also include a description of the root cause analysis, corrective
action analysis and implementation schedule in the annual report. If
corrective action is expected to take longer than 120 days after the
initial exceedance, the owner or operator must submit the corrective
action plan and corresponding implementation timeline to the
Administrator for approval within 75 days of the first measurement of
positive pressure. Owners or operators must keep records of corrective
action analyses. Owners or operators must include corrective action
records in the annual compliance report for corrective actions that
take greater than 60 days to implement.
4. Update and Approval of Design Plan
    The EPA is reaffirming some requirements and revising others to
address design plans. Design plans must continue to be prepared and
approved by a professional engineer. The landfill owner or operator
must then notify the Administrator that the plan is completed and
provide a copy of the plan's signature page. The Administrator will now
have 90 days to make a decision about whether the plan should be
submitted for review. If the Administrator chooses to review, the
approval process continues at outlined in this section. However, if the
Administrator indicates that submission is not required or doesn't
respond within 90 days, the landfill owner or operator can continue to
implement the plan with the recognition that they are proceeding at
their own risk. In the event that the design plan is required to be
modified to obtain approval, the owner/operator must take any steps
necessary to conform any prior actions to the approved design plan and
any failure to do so could result in an enforcement action.
    The EPA is also finalizing two criteria for when an affected source
must update its design plan and submit it to the Administrator for
approval. A revised design plan must be submitted on the following
timeline: (1) Within 90 days of expanding operations to an area not
covered by the previously approved design plan; and (2) prior to
installing or expanding the gas collection system in a manner other
than the one described in the previous design plan. The final rule
continues to require landfill owners or operators to prepare both an
initial and revised design plan.
5. Electronic Reporting
    The EPA is requiring owners or operators of new or modified MSW
Landfills to submit electronic copies of certain required performance
test reports, NMOC emission rate reports, annual reports, Tier 4
emission rate reports, and wet landfilling practices through the EPA's
Central Data Exchange (CDX) using the Compliance and Emissions Data
Reporting Interface (CEDRI). Owners or operators are allowed to
maintain electronic copies of the records in lieu of hardcopies to
satisfy federal recordkeeping requirements.
    The requirement to submit performance test data electronically to
the EPA applies only to those performance tests conducted using test
methods that are supported by the Electronic Reporting Tool (ERT). A
listing of the pollutants and test methods supported by the ERT is
available at: www3.epa.gov/ttn/chief/ert/ert_info.html. When the EPA
adds new methods to the ERT, a notice will be sent out through the
Clearinghouse for Inventories and Emissions Factors (CHIEF) Listserv
(www.epa.gov/air-emissions-inventories/emissions-inventory-listservs)
and a notice of availability will be added to the ERT Web site. You are
encouraged to check the ERT Web site regularly for up-to-date
information on methods supported by the ERT.
    The EPA believes that the electronic submittal of the reports
addressed in this rulemaking will increase the usefulness of the data
contained in those reports, is in keeping with current trends in data
availability, will further assist in the protection of public health
and the environment and will ultimately result in less burden on the
regulated community. Electronic reporting can also eliminate paper-
based, manual processes, thereby saving time and resources, simplifying
data entry, eliminating redundancies, minimizing data reporting errors
and providing data quickly and accurately to the affected facilities,
air agencies, the EPA and the public.
    The EPA Web site that stores the submitted electronic data,
WebFIRE, will be easily accessible to everyone and will provide a user-
friendly interface that any stakeholder could access. By making the
records, data, and reports addressed in this rulemaking readily
available, the EPA, the regulated community, and the public will
benefit when the EPA conducts its CAA-required reviews. As a result of
having reports readily accessible, our ability to carry out
comprehensive reviews will be increased and achieved within a shorter
period of time.
    We anticipate fewer or less substantial information collection
requests (ICRs) in conjunction with prospective CAA-required reviews
may be needed. Under an electronic reporting system, the EPA would have
air emissions and performance test data in hand; we would not have to
collect these data from the regulated industry. The data would provide
useful information on actual emissions, types of controls in place,
locations of facilities, and other data that the EPA uses in conducting
required reviews or future assessments. We expect this to result in a
decrease in time spent by industry to respond to data collection
requests. We also expect the ICRs to contain less extensive stack
testing provisions, as we will already have stack test data
electronically. Reduced testing requirements would be a cost savings to
industry. The EPA should also be able to conduct these required reviews
more quickly. While the regulated community may benefit from a reduced
burden of ICRs, the general public benefits from the agency's ability
to provide these required reviews more quickly, resulting in increased
public health and environmental protection.
    Air agencies could benefit from more streamlined and automated
review of the electronically submitted data. Having reports and
associated data in electronic format will facilitate review through the
use of software ``search'' options, as well as the downloading and
analyzing of data in spreadsheet format. The ability to access and
review air emission report information electronically will assist air
agencies to more quickly and accurately determine compliance with the
applicable regulations, potentially allowing a faster response to
violations which could minimize harmful air emissions. This benefits
both air agencies and the general public.
    For a more thorough discussion of electronic reporting required by
this rule, see the discussion in the 2014 proposed NSPS (79 FR 41818)
and the 2015 proposed Emission Guidelines (80 FR 52127). In summary, in
addition to supporting regulation development, control strategy
development, and other air pollution control activities, having an
electronic database populated with performance test data will save
industry, air agencies, and the EPA significant time, money, and effort
while improving the quality of emission inventories and air quality
regulations and enhancing the public's access to this important
information.

6. Landfills Recirculating Leachate or Adding Other Liquids
    In the 2014 ANPRM and 2015 proposed Emission Guidelines, the EPA
solicited input on whether additional action should be taken to address
emissions from wet landfills. As discussed in section VI.A.3 of this
preamble, there were a wide variety of perspectives provided in the
public comments, and while many commenters supported separate
thresholds for wet landfills, the EPA did not receive sufficient data
to support a separate subcategory for landfills adding leachate or
other liquids. In addition, the EPA has several other pending
regulatory actions that could affect wet landfills. Accordingly, the
EPA believes it is appropriate to further assess emissions from wet
landfills prior to taking additional action. Therefore, the EPA is
finalizing electronic reporting of additional data elements, as
discussed in Section V.A.2 of this preamble, to inform potential action
on wet landfills in the future.

C. Startup, Shutdown, and Malfunction Provisions

    The standards in 40 CFR part 60, subpart XXX apply at all times,
including periods of startup or shutdown, and periods of malfunction.
The EPA is reaffirming the work practice standard that is applicable
during SSM events wherein the landfill owner or operator is required to
shut down the gas mover system and close all valves in the collection
and control system potentially contributing to the venting of the gas
to the atmosphere within 1 hour of the collection or control system not
operating. The landfill owner or operator must also keep records and
submit reports of all periods when the collection and control device is
not operating.

D. Other Corrections and Clarifications

    The EPA is finalizing the following clarifications and corrections
to subpart XXX, which are consistent with the May 23, 2002 and
September 8, 2006 proposed amendments to subpart WWW.
    Consistent with the May 23, 2002 and September 8, 2006 proposed
amendments, the EPA is finalizing language in subpart XXX to exempt
owners/operators of boilers and process heaters with design capacities
of 44 megawatts or greater from the requirement to conduct an initial
performance test (40 CFR 60.762(b)(2)(iii)(B)).
    Consistent with the September 8, 2006 proposed amendments, the EPA
is finalizing the removal of the term ``combustion'' from the
requirement to monitor temperature of enclosed combustors (40 CFR
60.768(b)(2)(i) and 40 CFR 60.768(c)(1)(i)).
    Consistent with the September 8, 2006 proposed amendments, we are
amending the definition of ``household waste'' and adding a definition
of ``segregated yard waste'' in subpart XXX (40 CFR 60.761) to clarify
our intent regarding the applicability of the landfills NSPS to
landfills that do not accept household waste, but accept segregated
yard waste.

V. Summary of Significant Changes Since Proposal

A. Changes to Monitoring, Recordkeeping, and Reporting

1. Corrective Action
    We are revising the procedural requirements for correcting positive
pressure and temperature by allowing owners or operators 60 days to
correct exceedances. If the owner or operator cannot achieve negative
pressure or temperature of 55 degrees Celsius (131 degrees Fahrenheit)
by 60 days after the initial exceedance, owners or operators must
conduct a root cause analysis to identify the most appropriate
corrective action, which can include, but is not limited to, expanding
the GCCS. For corrective action that takes longer than 60 days, owners
or operators must develop an implementation schedule to complete the
corrective action as soon as practicable, but no more than 120 days
following the initial positive pressure or temperature reading.
Additionally, owners or operators must keep records of the corrective
action analysis. Owners or operators must submit the corrective action
and corresponding implementation timeline to the Administrator for
approval when implementation of the corrective action is expected to
take longer than 120 days after the initial exceedance.
    This change provides flexibility to owners or operators in
determining the appropriate remedy, as well as the timeline for
implementing the remedy.
2. Landfills Recirculating Leachate or Adding Other Liquids
    The EPA is adding electronic reporting requirements for wet areas
of landfills. The additional reporting applies to areas of the landfill
that have recirculated leachate within the last 10 years and to areas
where other liquids were added within the last 10 years.
    The EPA is requiring these landfills to annually report quantities
of liquids added and/or leachate recirculated. The first report will
contain historical quantities, where those data are available in on-
site records. The EPA is also requiring the landfill to report the
surface area over which the liquids are added or the leachate is
recirculated during each reporting year. The EPA is also requiring the
landfill to report the total waste disposed in the area with
recirculated leachate or added liquids as well as the annual waste
acceptance rates in those same areas. As discussed in Section VI.A.3 of
this preamble, this additional electronic reporting for wet landfills
will inform potential future action on wet landfills.
3. Portable Gas Analyzers
    We are allowing the use of portable gas composition analyzers in
conjunction with Method 3A to monitor the oxygen level at a wellhead.
The portable gas composition analyzer may be used to monitor the oxygen
level at a wellhead provided that the analyzer is calibrated and meets
all QA/QC requirements according to Method 3A. ASTM D6522-11 may be
used as an alternative to Method 3A for wellhead monitoring as long as
all the quality assurance is conducted as required by ASTM D6522-11. To
use ASTM D6522-11, the sample location must be prior to combustion.
    This change allows owners or operators to employ proven, reliable
devices that are commonly used in practice to measure wellhead
parameters. This change also eliminates the need for the landfill owner
or operator to request portable analyzers as an alternative, as well as
the need for agency review or approval of such requests. In addition to
providing reliable results when used properly, portable analyzers have
a number of benefits, including common use, the ability to provide
additional information on gas composition, and the ability to download
data to a spreadsheet for easy access and analysis.
4. More Precise Location Data
    The EPA is finalizing a requirement for landfills to report the
latitude and longitude coordinates of each surface emissions exceedance
(500 ppm methane or greater) with an instrument accuracy of at least 4
meters. This change will provide a more robust and long-term record of
GCCS performance. Landfill owners or operators and regulators can use
locational data to gain perspective on how the LFG collection system is
functioning over time and owners or operators will be able to track
trends in GCCS performance and cover practices to ensure a well
operating system and minimize emissions.

5. Update and Approval of Design Plan
    Landfill owners or operators must submit an updated design plan for
approval based on the following criteria: (1) Within 90 days of
expanding operations to an area not covered by the previously approved
design plan; and (2) before installing or expanding the gas collection
system in a way that is not consistent to the previous design plan. In
the final NSPS, the EPA removed a third criteria that was proposed:
Update the design plan prior to implementing an approved alternative
operating parameter value for temperature, nitrogen, or oxygen, if the
owner or operator has requested alternative operating parameter values.

B. Tier 4

    In the 2014 proposed NSPS, the EPA requested comment on whether to
include an additional tier, ``Tier 4,'' which would allow the use of
site-specific measurements of surface methane emissions to determine if
installation of a GCCS is required. In the 2015 proposed Emission
Guidelines, the EPA proposed Tier 4 to determine if a landfill needed
to install and operate a GCCS based on surface emission monitoring
using EPA Method 21 (80 FR 52112). As indicated in section IV.A.2 of
this preamble, the EPA is finalizing the use of Tier 4 SEM as an
alternative way of determining when a landfill must install a GCCS. The
details of the Tier 4 emission threshold methodology are presented in
sections IV.A.2 and VI.B of this preamble.

C. Changes To Address Closed or Non-Productive Areas

    Criteria for Removing GCCS. Since the emission threshold was
reduced from 40 Mg/yr in the 2014 NSPS proposal to 34 Mg/yr in the 2015
supplemental NSPS proposal, the EPA is editing the criteria for removal
in this final rule to be consistent with the final NMOC threshold of 34
Mg/yr. In addition, the EPA is finalizing an option for the landfill to
demonstrate the GCCS will be unable to operate for 15 years due to
declining gas flows to provide additional flexibility on low producing
areas. The GCCS can be capped, removed, or decommissioned when a
landfill owner or operator demonstrates that (1) the landfill is
closed, (2) the calculated NMOC emission rate at the landfill is less
than 34 Mg/yr on three consecutive test dates, and (3) the GCCS has
operated for at least 15 years or the landfill owner or operator can
demonstrate that the GCCS will be unable to operate for 15 years due to
declining gas flows.

D. Startup, Shutdown, and Malfunction Provisions

    In the 2014 NSPS proposal (79 FR 41812), the EPA clarified that
performance standards apply at all times, including periods of SSM. The
EPA also added requirements to estimate emissions during SSM events.
Consistent with Sierra Club v. EPA, 551 F.3d 1019 (D.C. Cir. 2008), the
EPA is clarifying that standards outlined in the NSPS apply at all
times. In recognition of the unique nature of landfill emissions and
consistent with the need for standards to apply at all times, including
during periods of SSM, the EPA is reaffirming a work practice standard
that applies during SSM events. During such events, owners or operators
must shut down the gas mover system and close within 1 hour all valves
in the collection and control system contributing to the potential
venting of the gas to the atmosphere. The landfill owner or operator
must also keep records and submit reports of all periods when the
collection and control device is not operating.

E. Definitions for Treated Landfill Gas and Treatment System and
Treatment System Monitoring

    The definition of treated LFG is clarified to include not only use
as a fuel for stationary combustion devices, but also allows other
beneficial uses such as vehicle fuel, production of high-Btu gas for
pipeline injection, and use as a raw material in a chemical
manufacturing process. Additionally, the treatment system is defined as
a system that filters, de-waters, and compresses LFG for sale or
beneficial use. Further, the EPA is requiring site-specific treatment
system monitoring plans that include monitoring parameters that address
filtration, de-watering, and compression to ensure the treatment system
is operating properly for the intended end use of the treated LFG.

F. Other Corrections and Clarifications

    The use of EPA Method 25A and Method 18 (on a limited basis, e.g.,
specific compounds like methane) are included in the final rule. Method
25A in conjunction with Method 18 (for methane) or Method 3C can be
used to determine NMOC for the outlet concentrations that are less than
50 ppm NMOC as carbon.

VI. Rationale for Significant Changes Since Proposal

    After considering public comments and further analyzing the
available data, the EPA made several changes in this final rule
relative to what we proposed. A complete list of public comments
received on the proposed rule and the responses to them can be viewed
in the document, ``Responses to Public Comments on EPA's Standards of
Performance for Municipal Solid Waste Landfills and Emission Guidelines
and Compliance Times for Municipal Solid Waste Landfills: Proposed
Rules'' (hereafter ``Response to Comments document''), which is
available in Docket EPA-HQ-OAR-2003-0215. This section of this preamble
summarizes comments and presents responses for only provisions that
have changed since the 2014 proposed NSPS and 2015 supplemental
proposal.

A. Changes to Monitoring, Recordkeeping, and Reporting

1. Wellhead Monitoring
    In the 2014 proposed NSPS, the EPA requested comment on alternative
wellhead monitoring requirements, including potential removal of the
temperature and nitrogen/oxygen monitoring requirements, or a reduction
in the frequency of this monitoring. For example, the EPA indicated
that it could reduce the frequency of wellhead monitoring for these
three parameters (temperature and nitrogen/oxygen) from monthly to a
quarterly or semi-annual schedule. The EPA requested comments on
whether the potential exclusion should apply to a subset of landfills
or landfill areas based on beneficial use of LFG.
    In the 2015 proposed Emission Guidelines, the EPA proposed to
remove the operational standards (i.e., the requirement to meet
operating limits) for temperature and nitrogen/oxygen at the wellheads,
thus removing the corresponding requirement to take corrective action
for exceedances of these parameters. This approach was taken to
eliminate the need for owners or operators to request higher operating
values (HOVs) for these parameters, submit alternative timelines for
corrective action, or expand the GCCS to address exceeding these
wellhead standards. The EPA proposed to maintain the requirement to
monitor nitrogen/oxygen and temperature on a monthly basis, but to
remove the requirement to report exceedances from fluctuations or
variations in these parameters in the annual reports. Instead of annual
reporting, the EPA proposed that landfill owners or operators maintain
the records of this monthly monitoring on site to inform any necessary
adjustments to the GCCS and make these records available to the
Administrator upon request. The EPA proposed to maintain the
requirement to

operate the GCCS at negative pressure and in a manner that collects the
most LFG and minimizes losses of LFG through the surface of the
landfill. The EPA also requested comments on whether it should add a
requirement to monitor wellhead flowrate, or any other wellhead
monitoring parameters, that would help to ensure a well-operated GCCS
(80 FR 52138).
    Comment: Several commenters want the EPA to maintain the wellhead
operational standards, including states, industry consultants, and
environmental organizations, with one environmental organization
stating that these wellhead parameters are the only warning signal for
potential fire hazard. One state stated that the removal of the
operational standards could lead to some landfill owners or operators
not operating the GCCS in an effective manner, thus creating a
potential for increased LFG emissions through the landfill surface.
    Many other commenters supported removing the nitrogen/oxygen and
temperature operational standards, including industry, some states, and
the Small Business Association. Several commenters indicated that a
lack of response or approval of HOV requests or alternative timelines
for corrective action, despite appropriate justification, is a
significant administrative barrier in the current NSPS and Emission
Guidelines. These commenters stated that a lack of response to or
approval of HOVs results in owners or operators having to install new
wells to correct for temperature or oxygen exceedance even though such
expansion of the GCCS does not correct the exceedance and may be
contrary to a well-operated GCCS. One commenter stated that removing
the operational standards would alleviate one of the most significant
barriers to installing interim gas collection measures and would
alleviate the corresponding administrative burden of requesting HOVs.
Other commenters stated that removing the operational standards would
not only reduce administrative burden, but would also facilitate early
installation of GCCS and the use of appropriate best management
practices to maximize gas collection. Two comments from state agencies
agreed with removing the operational standards, and agreed with
retaining monthly monitoring of temperature and nitrogen/oxygen and
retaining the corresponding monitoring data.
    Several commenters suggested that certain monitoring data should be
reported on a semi-annual basis so that agencies can identify or
prevent fires. For example, state agency commenters suggested that the
EPA require semi-annual reporting of wellhead readings above 5 percent
oxygen and 130 degrees Fahrenheit, which was supported by supplemental
comments received from the industry and industry trade organizations.
One commenter also suggested reporting of any subsurface fire. One
regional agency wanted the results to be reported if temperature
exceeds 150 degrees Fahrenheit and also suggested reporting any methane
to carbon dioxide ratio less than 1.
    Commenters that supported the removal of the operational standards
for temperature and nitrogen/oxygen also contended that the nitrogen/
oxygen and temperature wellhead parameters are poor indicators of
landfill fires or inhibited decomposition and that landfill owners or
operators already have their own incentive to prevent landfill fires.
Commenters added that expanding the LFG collection system by drilling
new wells may introduce more air into the landfill, which can
exacerbate a fire and actually increase oxygen content. Commenters that
favored retaining the operational standards for temperature and
nitrogen/oxygen contend that temperature and nitrogen/oxygen data are
essential to inform regulators of the presence of potential for a
landfill fire.
    Response: After carefully considering public comments and available
data, the EPA is removing the operational standards (i.e., the
requirement to meet operating limits) for nitrogen/oxygen, but not
temperature. Landfill owners or operators must continue to monitor
nitrogen/oxygen on a monthly basis, however, to ensure that the GCCS is
well maintained and operated, collects the most LFG, and minimizes
losses of LFG through the surface of the landfill. Landfill owners or
operators must maintain records of this monthly monitoring and make
these records available to the Administrator upon request. The EPA is
requiring monthly monitoring and recordkeeping for these wellhead
monitoring parameters (i.e., oxygen, nitrogen, temperature, and
pressure), since these are key indicators that are already being
monitored by landfill owner or operators to determine how well the
landfill is being operated, including the capturing and destroying
landfill gas, promoting efficient anaerobic decomposition and/or
preventing landfill fires.
    Because of concerns regarding fire hazards, the EPA is retaining
the operational standard for temperature. Landfill owners or operators
must electronically submit, as part of their annual report, all
readings that show LFG temperatures greater than 55 degrees Celsius
(131 degrees Fahrenheit), and document the root cause and corrective
action taken to correct for this exceedance, as discussed in section
VI.A.2 of this preamble. While several commenters supported removing
the temperature parameters, other commenters were concerned with fire
risks if the parameter was removed. In addition, given the EPA
experience with consent decrees and other enforcement actions involving
elevated temperature values, the EPA has decided to retain temperature
as an operating standard in the final rule. This overall approach will
reduce the number of requests for HOVs and alternative timeliness for
nitrogen/oxygen parameters. In addition, note that regulatory agencies
can request data records of oxygen, nitrogen, or temperature
monitoring, as measured on a monthly basis, at any time.
    Landfills are subject to 40 CFR part 60, subpart A. These
provisions require landfill owners or operators, to the extent
practicable, to maintain and operate any affected facility including
associated air pollution control equipment in a manner consistent with
good air pollution control practice for minimizing emissions. Due to
the extreme environmental consequences of a subsurface landfill fire,
these provisions obligate landfill owners or operators to take all
practical steps necessary to avoid landfill fires. While this action
removes requirements to meet operational standards for nitrogen/oxygen
at wellheads and to make corrective actions, landfill owners or
operators must continue all due diligence to ensure that the GCCS is
not overdrawn, thereby creating a flammable subsurface environment.
Because the corrective action requirements for certain parameters have
been retained, the EPA is reaffirming its provisions for HOVs. The HOV
provisions were originally enacted to address variations in temperature
between landfills and between wells. With a sufficient demonstration
(i.e., supporting data showing the elevated parameter does not cause
fires or significantly inhibit anaerobic decomposition by killing
methanogens), an HOV may be established for temperature, nitrogen, or
oxygen at a particular well. The EPA encourages regulatory authorities
review requests for HOVs in a timely manner and to make use of these
mechanisms where appropriate.\38\
---------------------------------------------------------------------------

    \38\ The EPA asserts the importance of case specific HOV
requests and approvals. However, to address concerns from HOV
request reviewers and those submitting requests, an example of
regulatory guidance for HOV demonstrations can be found at http://www.epa.ohio.gov/portals/34/document/guidance/gd_1002.pdf.

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

2. Corrective Action
    In a 1998 Federal Register notice (63 FR 32748, June 16, 1998), the
EPA amended the wellhead monitoring provisions of 40 CFR part 60,
subpart WWW to allow an alternative timeline for correcting wellhead
exceedances to be submitted to the Administrator for approval. The rule
change made the wellhead monitoring provisions consistent with the SEM
provisions, which allow an alternative remedy and corresponding
timeline for correcting an exceedance to be submitted to the
Administrator for approval. The EPA noted in the 1998 preamble that any
timeline extending more than 120 days must be approved by the
regulating agency. Since 1998, questions have been raised about the
timing of correcting wellhead exceedances and whether a landfill needs
agency approval for corrective action timelines that exceed 15 calendar
days but are less than the 120 days allowed for expanding the GCCS.
    The EPA clarified in the proposed subpart XXX that, with the
exception of system expansion, all corrective actions expected to
exceed 15 calendar days should be submitted to the agency for approval
of an alternate timeline. Additionally, the EPA proposed that if a
landfill owner or operator expects the system expansion to exceed the
120-day allowance period, it should submit a request and justification
for an alternative timeline. Further, the EPA solicited comment on
extending the requirement for notification from 15 days to as soon as
practicable, but no later than 60 days.
    The proposed Emission Guidelines noted that the proposed removal of
operational standards for nitrogen/oxygen and temperature would
drastically reduce the number of requests for alternative corrective
action timelines. However, the requirement to maintain negative
pressure at the wellhead remained in the proposal. Therefore, the EPA
proposed a timeline for correcting positive pressure, including a
requirement to submit an alternative corrective action timeline request
to the Administrator if the landfill cannot restore negative pressure
within 15 calendar days or the initial failure to maintain negative
pressure and the landfill is unable to (or does not plan to) expand the
gas collection within 120 days of the initial exceedance.
    The EPA explained in the preamble for the 2015 Emission Guidelines
proposal that it did not specify a schedule in the proposed rule
language by when a landfill would need to submit alternative timeline
requests because the EPA determined that investigating and determining
the appropriate corrective action, as well as the schedule for
implementing corrective action, would be site specific and depend on
the reason for the exceedance (80 FR 52126). In addition, the EPA
requested comment (80 FR 52126) on an alternative timeline that extends
the requirement for notification from 15 days to as soon as
practicable, but no later than 60 days from when an exceedance is
identified.
    Comment: The EPA received comments on the proposed changes,
including the time allowed for corrective action and for submitting
alternative timeline requests for approval by the Administrator.
Regarding the timeframe for submitting a request, several state
agencies recommended extending the 15-day timeline for a request to be
submitted and indicated that 15 days is not sufficient time to evaluate
the problem and plan for corrective action, which may often involve
construction activities. There were varied opinions from the state
agencies on what length of time beyond 15 days is appropriate. Two
agencies supported an extension to as soon as practicable but no later