[Federal Register Volume 79, Number 137 (Thursday, July 17, 2014)]
[Proposed Rules]
[Pages 41795-41843]
[FR Doc No: 2014-16405]

Vol. 79

Thursday,

No. 137

July 17, 2014

Part IV

Environmental Protection Agency

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40 CFR Part 60

Standards of Performance for Municipal Solid Waste Landfills; Proposed
Rule

Federal Register / Vol. 79 , No. 137 / Thursday, July 17, 2014 /
Proposed Rules

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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 60

[EPA-HQ-OAR-2003-0215; FRL-9912-12-OAR]
RIN 2060-AM08

Standards of Performance for Municipal Solid Waste Landfills

AGENCY: Environmental Protection Agency.

ACTION: Proposed rule.

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SUMMARY: The Environmental Protection Agency (EPA) is proposing a new
subpart, 40 CFR part 60, subpart XXX 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 applies to landfills
that commence construction, reconstruction, or modification after July
17, 2014. The proposed standards reflect changes to the population of
landfills and an analysis of the timing and methods for reducing
emissions. The proposed standards also address other regulatory issues
including the definition of landfill gas treatment systems, among other
topics. The new subpart will reduce emissions of landfill gas, which
contains both nonmethane organic compounds and methane. These avoided
emissions will improve air quality and reduce public health and welfare
effects associated with exposure to landfill gas emissions.

DATES: Comments. Comments must be received on or before September 15,
2014.
    Public Hearing. If anyone contacts the EPA requesting a public
hearing by July 22, 2014, we will hold a public hearing on August 12,
2014, in Washington, DC at the William Jefferson Clinton East Building,
Room 1153, 1201 Constitution Avenue NW., Washington, DC 20004. The
public hearing will convene at 9:00 a.m. and end at 6:00 p.m. (Eastern
Standard Time). There will be a lunch break from 12:00 p.m. to 1:00
p.m. Please contact Ms. Virginia Hunt at<PHONE_NUMBER> or at
<EMAIL_ADDRESS>to register to speak at one of the hearings. The
last day to pre-register in advance to speak at the hearings will be
Friday August 8, 2014. Additionally, requests to speak will be taken
the day of the hearing at the hearing registration desk, although
preferences on speaking times may not be able to be fulfilled. If you
require the service of a translator or special accommodations such as
audio description, please let us know at the time of registration.
    If no one contacts the EPA requesting a public hearing to be held
concerning this proposed rule by July 22, 2014, a public hearing will
not take place. If a hearing is held, it will provide interested
parties the opportunity to present data, views or arguments concerning
the proposed action. The EPA will make every effort to accommodate all
speakers who arrive and register. Because this hearing, if held, will
be at U.S. government facilities, individuals planning to attend the
hearing should be prepared to show valid picture identification to the
security staff in order to gain access to the meeting room. In
addition, you will need to obtain a property pass for any personal
belongings you bring with you. Upon leaving the building, you will be
required to return this property pass to the security desk. No large
signs will be allowed in the building, cameras may only be used outside
of the building and demonstrations will not be allowed on federal
property for security reasons.
    The EPA may ask clarifying questions during the oral presentations,
but will not respond to the presentations at that time. Written
statements and supporting information submitted during the comment
period will be considered with the same weight as oral comments and
supporting information presented at the public hearing. Commenters
should notify Ms. Hunt if they will need specific equipment, or if
there are other special needs related to providing comments at the
hearings. Verbatim transcripts of the hearing and written statements
will be included in the docket for the rulemaking. The EPA will make
every effort to follow the schedule as closely as possible on the day
of the hearing; however, please plan for the hearing to run either
ahead of schedule or behind schedule. Information regarding the hearing
(including information as to whether or not one will be held) will be
available at: http://www.epa.gov/ttnatw01/landfill/landflpg.html.

ADDRESSES: Submit your comments, identified by Docket ID Number EPA-HQ-
OAR-2003-0215, by one of the following methods:
     Federal eRulemaking Portal: http://www.regulations.gov.
Follow the online instructions for submitting comments.
     Email<EMAIL_ADDRESS>Include docket ID No. EPA-
HQ-OAR-2003-0215 in the subject line of the message.
     Fax:<PHONE_NUMBER>. Attention Docket ID No. EPA-HQ-OAR-
2003-0215.
     Mail: Environmental Protection Agency, EPA Docket Center
(EPA/DC), Mailcode 28221T, Attention Docket ID No. EPA-HQ-OAR-2003-
0215, 1200 Pennsylvania Avenue NW., Washington, DC 20460. Please
include a total of two copies. In addition, please mail a copy of your
comments on the information collection provisions to the Office of
Information and Regulatory Affairs, Office of Management and Budget,
Attn: Desk Officer for EPA, 725 17th Street NW., Washington, DC 20503.
     Hand/Courier Delivery: EPA Docket Center, Room 3334, EPA
WJC West Building, 1301 Constitution Avenue NW., Washington, DC 20004.
Such deliveries are only accepted during the Docket's normal hours of
operation, and special arrangements should be made for deliveries of
boxed information.
    Instructions: Direct your comments to Docket ID No. EPA-HQ-OAR-
2003-0215. The EPA's policy is that all comments received will be
included in the public docket without change and may be made available
online at http://www.regulations.gov, including any personal
information provided, unless the comment includes information claimed
to be confidential business information (CBI) or other information
whose disclosure is restricted by statute.
    Do not submit information that you consider to be CBI or otherwise
protected through http://www.regulations.gov or email. Send or deliver
information identified as CBI to only the mail or hand/courier delivery
address listed above, attention: Mr. Roberto Morales, OAQPS Document
Control Officer (Room C404-02), Office of Air Quality Planning and
Standards, U.S. EPA, Research Triangle Park, NC 27711, Attention Docket
ID No. EPA-HQ-OAR-2003-0215. The http://www.regulations.gov Web site is
an ``anonymous access'' system, which means the EPA will not know your
identity or contact information unless you provide it in the body of
your comment. If you send an email comment directly to the EPA without
going through http://www.regulations.gov, your email address will be
automatically captured and included as part of the comment that is
placed in the public docket and made available on the Internet. If you
submit an electronic comment, the EPA recommends that you include your
name and other contact information in the body of your comment and with
any disk or CD-ROM you submit. If the EPA cannot read your comment due
to technical difficulties and cannot contact

you for clarification, the EPA may not be able to consider your
comment. Electronic files should avoid the use of special characters,
any form of encryption, and be free of any defects or viruses.
    Docket: 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., CBI or other information
whose disclosure is restricted by statute. Certain other material, such
as copyrighted material, will be publicly available only in hard copy.
Publicly available docket materials are available either electronically
in http://www.regulations.gov or in hard copy at the Air Docket, EPA/
DC, William Jefferson Clinton West Building, Room B102, 1301
Constitution Ave. NW., Washington, DC. This Docket Facility is open
from 8:30 a.m. to 4:30 p.m., Monday through Friday, excluding legal
holidays. The telephone number for the Public Reading Room is (202)
566-1744, and the telephone number for the Air Docket is (202) 566-
1742.

FOR FURTHER INFORMATION CONTACT: For information concerning this
proposal, 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:
    World Wide Web (WWW). In addition to being available in the docket,
an electronic copy of proposed subpart XXX for 40 CFR part 60 is
available on the Technology Transfer Network (TTN) Web site. Following
signature, the EPA will post a copy of the proposed subpart XXX on the
TTN's policy and guidance page for newly proposed or promulgated rules
at http://www.epa.gov/ttnatw01/landfill/landflpg.html. The TTN provides
information and technology exchange in various areas of air pollution
control.
    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
CAA Clean Air Act
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
CRDS Cavity ringdown spectroscopy
DOC Degradable organic carbon
EPA Environmental Protection Agency
ERT Electronic Reporting Tool
FLIR Forward-looking infrared
FTIR Fourier Transform Infrared
GCCS Gas collection and control system
GHGRP Greenhouse Gas Reporting Program
GWP Global warming potential
HAP Hazardous air pollutants
ICR Information collection request
IRIS Integrated Risk Information System
lb/MMBtu Pounds per million British thermal unit
LFG Landfill gas
LFGCost Landfill Gas Energy Cost Model
LMOP Landfill Methane Outreach Program
m\3\ Cubic meters
Mg Megagram
Mg/yr Megagram per year
MSW Municipal solid waste
MW Megawatt
MWh Megawatt hour
NAICS North American Industry Classification System
NMOC Nonmethane organic compound
NSPS New source performance standards
NSR New Source Review
NTTAA National Technology Transfer and Advancement Act
OAQPS Office of Air Quality Planning and Standards
OMB Office of Management & Budget
ppm Parts per million
ppmvd Parts per million by dry volume
RCRA Resource Conservation and Recovery Act
RFA Regulatory Flexibility Act
RIA Regulatory impacts analysis
RPM Radial plume mapping
SBAR Small Business Advocacy Review
SER Small entity representative
SISNOSE Significant impact on a substantial number of small entities
SSM Startup, shutdown and malfunction
TDL Tunable diode laser
tpy Tons per year
TTN Technology Transfer Network
USG U.S. government
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. What should I consider as I prepare my comments?
III. Background
    A. Legal Authority
    B. What is the purpose and scope of this action?
    C. Where in the Code of Federal Regulations will these changes
appear?
IV. Summary of Proposed Changes Based on Periodic Review of the MSW
Landfills NSPS Under the CAA
V. What analyses did the EPA conduct to determine BSER?
    A. Review of Control Technology
    B. What data and control criteria did the EPA consider in
evaluating potential changes to the timing of installing, expanding,
and removing the GCCS?
    C. What control options did the EPA consider?
    D. What are the implementation concerns with changing the design
capacity criteria?
    E. What are the implementation concerns with reducing the NMOC
threshold?
    F. What are the implementation concerns with shortening the
initial or expansion lag times?
    G. Request for Comment on BSER
VI. Rationale for the Proposed Changes Based on Review of the NSPS
    A. What are the environmental impacts and costs associated with
the baseline?
    B. How did the EPA determine which control option to propose?
VII. Summary of Clarifications and Resolutions That Are the Result
of Implementation Activity
    A. Definitions for Treated Landfill Gas and Treatment System and
Treatment System Monitoring
    B. Startup, Shutdown and Malfunction Provisions
    C. Closed Areas
    D. Surface Monitoring
    E. Electronic Reporting
    F. Wellhead Monitoring Requirements
    G. Requirements for Updating the Design Plan
    H. Submitting Corrective Action Timeline Requests
    I. Other Corrections and Clarifications
VIII. Rationale for the Clarifications and Resolutions That Are the
Result of Implementation Activity
    A. Definitions for Treated Landfill Gas and Treatment System and
Treatment System Monitoring
    B. Startup, Shutdown and Malfunction Provisions
    C. Closed Areas
    D. Surface Monitoring
    E. Electronic Reporting
    F. Wellhead Monitoring Requirements
    G. Requirements for Updating Design Plan
    H. Submitting Corrective Action Timeline Requests
    I. Other Corrections and Clarifications
IX. Request for Comment on Specific Provisions
    A. Definitions for Treated Landfill Gas and Treatment System and
Treatment System Monitoring
    B. Wellhead Monitoring Requirements
    C. Enhanced Surface Monitoring Requirements
    D. Alternative Emission Threshold Determination Techniques
X. Impacts of Proposed Revisions
    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?

    H. What are the health and welfare effects of LFG emissions?
XI. 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
    C. Regulatory Flexibility Act
    D. Unfunded Mandates Reform Act
    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
    J. Executive Order 12898: Federal Actions to Address
Environmental Justice in Minority Populations and Low-Income
Populations

I. Executive Summary

A. Purpose of Regulatory Action

    The EPA has conducted an initial review of the Standards of
Performance for Municipal Solid Waste Landfills (landfill new source
performance standards or landfills NSPS). The EPA's review is ongoing
and will be informed by, among other matters, comments received on
today's proposed action. Based on its initial review, the EPA is
proposing a number of changes to the existing landfills NSPS. In order
to avoid possible confusion regarding which MSW landfills would
actually be subject to any revised, or new, requirements, the EPA is
establishing a new subpart XXX (40 CFR part 60, subpart XXX) rather
than merely updating existing subpart WWW (40 CFR part 60, subpart
WWW). The requirements in new subpart XXX will apply to MSW landfills
for which construction, modification, or reconstruction is commenced on
or after July 17, 2014. The requirements in subpart WWW will continue
to apply to MSW landfills on which construction, modification or
reconstruction was commenced on or after May 30, 1991 and before July
17, 2014. Note that this preamble uses both of the terms ``MSW
landfills'' and ``landfills'' to refer to MSW landfills.
1. Need for Regulatory Action
    Several factors led to today's proposed action. First, section 111
of the Clean Air Act (CAA) (42 U.S.C. Sec.  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 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 and operators, as well as
regulators, need clarification regarding issues that have arisen during
implementation of the existing standards. Implementation issues include
the definition of landfill gas treatment, among other topics.
2. Legal Authority
    CAA section 111(b)(1)(B) (42 U.S.C. Sec.  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. Sec.  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 propose 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.\1\ Proposed subpart XXX would
appear in 40 CFR part 60 and would apply to landfills that commence
construction, reconstruction, or modification on or after July 17,
2014.
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    \1\ 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 will 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.
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B. Summary of Major Provisions

    The proposed new subpart retains the same design capacity threshold
but reduces the non-methane organic compounds (NMOC) emission threshold
at which MSW landfills must install controls. The new subpart also
resolves or clarifies issues that the EPA and stakeholders identified
during implementation of the current landfills NSPS.
    Thresholds for installing controls. Under the current NSPS, an MSW
landfill that has a design capacity of 2.5 million megagrams (Mg) and
2.5 million cubic meters (m\3\) must install and start up a gas
collection control system within 30 months after landfill gas emissions
reach or exceed a level of 50 Mg NMOC per year. (A megagram is also
known as a metric ton, which is equal to 1.1 U.S. short tons or about
2,205 pounds.) The current NSPS is referred to as the ``baseline'' in
this document. Proposed subpart XXX retains the same design capacity
threshold as the baseline, but reduces the NMOC emission threshold to
40 Mg/yr. 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.
    Landfill gas treatment. The EPA is addressing two issues related to
landfill gas treatment. First, the EPA is proposing to clarify that the
use of treated landfill gas 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 proposing to clarify what constitutes landfill gas treatment.
For filtration and dewatering, the definition contains specific
numerical values that would provide long-term protection of the
combustion equipment, which would support good combustion. We are also
proposing to clarify monitoring, recordkeeping, and reporting
requirements for treatment systems.
    Startup, shutdown and malfunction. In today's action, the EPA is
proposing that the standards in proposed subpart XXX apply at all
times, including periods of startup or shutdown, and periods of
malfunction. In addition, to enable the EPA to determine the severity
of an emissions exceedance for periods when the gas collection system
or a control device is not operating, the EPA is proposing to add a
recordkeeping and reporting requirement for landfill owners or
operators to estimate emissions during such periods.
    Other clarifications. The EPA is proposing other clarifications to
address issues that have been raised by landfill owners or operators
during implementation of the current NSPS. These other clarifications
include improvements to criteria for exempting areas from collection
and control, adding criteria for when an affected source must update
its design plan, and clarifying when landfill owners or operators must
submit corrective action timeline requests. We intend to address

clarifications and other implementation issues for existing landfills
in a separate rulemaking.

C. Costs and Benefits

    An MSW landfill owner or operator is expected to install the least-
cost control for collecting and combusting landfill gas. The control
costs include the costs to install and operate a GCCS. For certain
landfills that were expected to generate revenue by using the landfill
gas for energy, revenue from electricity sales was incorporated into
the net control costs. The annualized costs also include testing and
monitoring costs.
    Proposed subpart XXX, which tightens the NMOC emissions threshold
from 50 to 40 Mg/yr NMOC, would achieve reductions of 79 Mg NMOC/yr and
12,300 Mg methane/yr (about 307,600 Mg CO2e/yr) beyond the
baseline in year 2023. The associated annualized net cost for proposed
subpart XXX is estimated to be an additional $471,000 (2012$) in 2023.
The EPA expects that the avoided emissions will result in improvements
in air quality and reduce health effects associated with exposure to
air pollution related emissions, and result in climate co-benefits due
to reductions of the methane component of landfill gas. However,
because this rulemaking is not an ``economically significant regulatory
action'' under Executive Order 12866 because it is not likely to have
an annual effect on the economy of $100 million or more, we have not
conducted a Regulatory Impact Analysis (RIA) or a benefits analysis.
The baseline NSPS in effect today is estimated to achieve a reduction
of 610 Mg/yr NMOC and 94,800 Mg/yr methane (about 2.4 million Mg/yr
CO2e) in 2023, compared to the absence of control (see
section VI.A. of this preamble and the Economic Impact Analysis for
more detail). The associated annualized net cost of the baseline is
estimated to be $2.7 million ($2012) in 2023.

II. General Information

A. Does this action apply to me?

    This proposal affects municipal solid waste (MSW) landfills and
associated solid waste management programs. Affected categories and
entities include those listed in Table 1 of this preamble.

                       Table 1--Regulated Entities
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                                                   Examples of affected
              Category                NAICS \a\         facilities
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Industry: Air and water resource          924110  Solid waste landfills.
 and solid waste management.
Industry: Refuse systems--solid           562212  Solid waste landfills.
 waste landfills.
State, local, and tribal government       924110  Administration of air
 agencies.                                         and water resource
                                                   and solid waste
                                                   management programs.
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\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
proposed 40 CFR 60.760 of subpart XXX. If you have any questions
regarding the applicability of the proposed subpart to a particular
entity, contact the person listed in the preceding FOR FURTHER
INFORMATION CONTACT section.

B. What should I consider as I prepare my comments?

1. Submitting CBI
    Clearly mark the part or all of the information that you claim to
be CBI. For CBI information in a disk or CD ROM that you mail to the
EPA, mark the outside of the disk or CD ROM as CBI and then identify
electronically within the disk or CD ROM the specific information that
is claimed as CBI. In addition to one complete version of the comment
that includes information claimed as CBI, a copy of the comment that
does not contain the information claimed as CBI must be submitted for
inclusion in the public docket. Information marked as CBI will not be
disclosed except in accordance with procedures set forth in 40 CFR part
2.
    Do not submit information that you consider to be CBI or otherwise
protected through http://www.regulations.gov or email. Send or deliver
information identified as CBI to only the following address: Mr.
Roberto Morales, OAQPS Document Control Officer (Room C404-02), U.S.
EPA, Research Triangle Park, NC 27711, Attention Docket ID No. EPA-HQ-
OAR-2003-0215.
    If you have any questions about CBI or the procedures for claiming
CBI, please consult the person identified in the FOR FURTHER
INFORMATION CONTACT section.
2. Docket
    The docket number for the municipal solid waste landfills new
source performance standards (40 CFR part 60, subpart XXX) is Docket ID
No. EPA-HQ-OAR-2003-0215. Docket ID No. A-88-09 contains supporting
information for related 40 CFR part 60, subparts WWW and Cc.

III. Background

    In June 2013, President Obama issued a Climate Action Plan which,
among other matters, directed the EPA and five other federal agencies
to develop a comprehensive interagency strategy to reduce methane
emissions. The plan recognized that methane emissions constitute a
significant percentage of domestic greenhouse gas (GHG) emissions,
highlighted reductions in methane emissions since 1990, and outlined
specific actions that could be taken to achieve additional progress.
Specifically, the federal agencies were instructed 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.''
    As a follow up to the 2013 Climate Action Plan, the Climate Action
Plan: Strategy to Reduce Methane Emissions (the Methane Strategy) was
released in March 2014. The focus on reducing methane emissions is due
to the fact that methane is a potent GHG with a global warming
potential that is 25 times greater than carbon dioxide.\2\ Methane has
an atmospheric life of 12 years, and because of its potency as a GHG
and its atmospheric life, reducing methane emissions achieves a near-
term beneficial impact in mitigating global climate change.
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    \2\ IPCC Fourth Assessment Report (AR4), 2007. Climate Change
2007: The Physical Science Basis. Contribution of Working Group I to
the Fourth Assessment Report of the Intergovernmental Panel on
Climate Change [Core Writing Team, Pachauri, R.K. and Reisinger, A.
(eds.)]. IPCC, Geneva, Switzerland, 104 pp.
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    The targeted strategy noted that the landfill standards at issue
here and voluntary programs already in place

have considerably reduced methane emissions.\3\ With respect to
landfills, the Methane Strategy directs the agency to build upon
progress to date through updates to the EPA's rules for reducing
emissions from new, modified, and reconstructed landfills, issuance of
an Advance Notice of Proposed Rulemaking (ANPRM) to explore options to
address emissions from existing landfills, and encouragement of
beneficial use through voluntary programs.
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    \3\ Climate Action Plan: Strategy to Reduce Methane Emissions.
March 2014. p.5. http://www.whitehouse.gov/sites/default/files/strategy_to_reduce_methane_emissions_2014-03-28_final.pdf.
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    The EPA has long recognized the climate benefits associated with
reducing methane emissions from landfills. In the 1991 Landfill NSPS
Background Information Document \4\ the EPA noted that reduction of
methane emissions from MSW landfills is one of the many options
available to reduce possible global warming. When the EPA promulgated
the NSPS for MSW landfills, which regulates MSW landfill emissions
(commonly referred to as landfill gas), in 1996, the EPA noted the co-
benefits of controlling methane, but recognized the then relatively
limited understanding of GHG and their effect on global climate change
(61 FR 9917, March 12, 1996). In 1996, we stated:
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    \4\ 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.

    An ancillary benefit from regulating air emissions from MSW
landfills is a reduction in the contribution of MSW landfill
emissions to global emissions of methane. Methane is a major
greenhouse gas, and is 20 to 30 times more potent than
CO2 on a molecule-per-molecule basis. There is a general
concern within the scientific community that the increasing
emissions of greenhouse gases could lead to climate change, although
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the rate and magnitude of these changes are uncertain.

    Since 1996, the EPA and the scientific community have gained a
better understanding of GHGs, such as methane, and their effects on
climate change and human health and welfare. In 2009, the EPA
Administrator issued the document known as the Endangerment Finding
under CAA section 202(a)(1).\5\ In the Endangerment Finding, which
focused on public health and public welfare impacts within the United
States, the Administrator found that elevated concentrations of GHGs in
the atmosphere may reasonably be anticipated to endanger the public
health and welfare of current and future generations.
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    \5\ ``Endangerment and Cause or Contribute Findings for
Greenhouse Gases Under Section 202(a) of the Clean Air Act,'' 74 FR
66496 (December 15, 2009) (``Endangerment Finding'').
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    There is now scientific consensus that GHGs affect climate change
and, as recognized by the President in the Methane Strategy, this
scientific consensus increases the need for the EPA to examine
regulatory options for reducing methane emissions. The EPA is currently
reviewing the MSW Landfills NSPS in light of the President's Climate
Action Plan, the Methane Strategy, and improvements in the science
related to GHG emissions, and is exploring opportunities to achieve
additional reductions in emissions, including methane emissions.

A. Legal Authority

    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. Sec.  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. Sec.  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. Sec.  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 thresholds and emission level of the standards.
    CAA section 111(a)(1) (42 U.S.C. Sec.  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 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. 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. Sec.  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
regulated for that source category 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., parts per million (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).)

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

    The purpose of this action is (1) to review the MSW landfills NSPS,
(2) to propose a resolution or to provide clarification regarding
implementation issues that were addressed in prior proposed rules
published on May 23, 2002 (67 FR 36475) and September 8, 2006 (71 FR
53271), as they apply to new sources, and (3) to take comment on
specific aspects of EPA's review that will be considered in
promulgating the final NSPS standard. These proposed revisions appear
in the proposed 40 CFR part 60 subpart XXX.
    Many changes have occurred in the landfill industry since the
landfills NSPS was originally promulgated in 1996 that have
necessitated this review. Among the factors contributing to the need
for review are the following: Changes in landfill characteristics
(i.e., size, ownership, age) and population; proliferation of landfill
gas energy projects; the availability of more comprehensive data on
landfills from mandatory (Greenhouse Gas Reporting Program (GHGRP)) and
voluntary EPA programs; and the introduction of new techniques for
monitoring landfill gas emissions. The number and size distribution of
MSW landfills in the United States has also evolved since 1996. Public
opposition to local MSW disposal facilities and the increasing cost of
disposal at locations near where the waste is generated have resulted
in consolidation and led to an increase in long-distance hauls to large
regional landfills. As a result, the corresponding emission profiles
and per landfill compliance costs have also changed.
    The number of landfill gas to energy projects has also increased
substantially. In 1996, there were approximately 160 operational
landfill gas energy projects and approximately 700 candidate landfills
according to data obtained by the EPA Landfill Methane Outreach Program
(LMOP). According to LMOP, as of March 2014, there were 636 operational
projects using landfill gas to produce energy and 450 landfills that
remain candidates for energy recovery. LMOP is a voluntary assistance
program that encourages recovery and beneficial use of landfill gas,
and in turn, helps to reduce methane emissions from landfills. During
our review, the EPA has also become aware of techniques and procedures
for monitoring landfill gas emissions that were not available at the
time of the original rule.
    The EPA is required to review the MSW Landfills NSPS and sections
IV, V, and VI of this preamble present our initial determinations. In
addition, the EPA has determined that it is appropriate to propose a
revised NSPS based on these initial determinations.
    This action also provides clarification regarding issues that arose
during the implementation of the current landfills regulations and
proposes regulatory text addressing some of those issues. We addressed
these issues in previous notices as published on May 23, 2002 (67 FR
36475) and September 8, 2006 (71 FR 53271). These issues include the
definition of landfill gas treatment and other topics such as surface
monitoring, how to address closed areas of landfills and when to allow
removal of controls. Although the cited notices addressed these issues
in the context of subparts Cc and WWW, the clarifications and
resolutions discussed in sections VII and VIII of this preamble would
affect only landfills that commence construction, reconstruction, or
modification on or after July 17, 2014.
    The EPA plans to address amendments and clarifications resulting
from implementation activities for landfills subject to 40 CFR part 60,
subpart WWW and state or federal plans implementing subpart Cc in a
separate action.
    This action also requests comment on specific aspects of the EPA's
review, the consideration of which will be integral to the EPA in
taking final action to promulgate a new NSPS. These provisions include
landfill gas treatment, wellhead monitoring, and surface monitoring.
See section IX of this preamble for a discussion of those provisions.

C. Where in the Code of Federal Regulations will these changes appear?

    The EPA is proposing to add new subpart XXX to 40 CFR part 60.
Subpart XXX would apply to landfills that commence construction,
reconstruction, or modification on or after July 17, 2014. Proposed
subpart XXX in 40 CFR part 60 contains a revision to the NMOC emission
rate threshold, as well as provisions that provide clarification and
proposed resolutions to technical and implementation issues.

IV. Summary of Proposed Changes Based on Periodic Review of the MSW
Landfills NSPS Under the CAA

    The EPA is proposing to reduce the NMOC emission rate threshold for
installing and operating a gas collection and control system to 40 Mg/
yr from the current NSPS level of 50 Mg/yr. The proposal retains the
design capacity cutoff of 2.5 million Mg and 2.5 million cubic meters
that appears in subpart WWW. See sections V and VI of this preamble for
a discussion of the proposed rule changes. The new subpart also
resolves or clarifies issues that the EPA and stakeholders identified
during implementation of the current landfills NSPS.
    The EPA is proposing this revised emission threshold that takes
into account the total methane emission reductions that can be achieved
in addition to the reductions of NMOC emissions that are realized when
the GCCS is installed at an earlier point in time. While the proposal
continues to require measurement of NMOC as a surrogate for landfill
gas, the EPA asserts that the methane reductions achieved are
consistent with the President's Methane Strategy as described in
section III of this preamble.

V. What analyses did the EPA conduct to determine BSER?

    The EPA first undertook a review to determine whether a well
designed and well operated landfill GCCS, which EPA previously
determined was BSER for controlling landfill gas, remains BSER for that
purpose. The EPA considered GCCSs, as well as other emission control
technologies that are either currently in place at landfills, or could
be adopted, and considered the emission reductions achieved by those
systems. Based on this analysis, the EPA determined that a well
designed and operated landfill GCCS remains BSER. The EPA then
undertook an analysis to determine whether applying the existing
criteria for installing and operating a landfill GCCS to the expected
population of new MSW landfills remains the preferred approach to
implementing BSER. To do so, the EPA developed and applied a model
program in Microsoft[supreg] Access to revisit the design capacity
cutoff, the NMOC emission rate cutoff, and the time allowed for
installing and expanding a gas collection system. In addition to
reviewing the thresholds that determine the schedule for installing and
expanding the GCCS system, the EPA also reviewed whether the schedule
for removing the GCCS needed adjustment (see section V.A of this
preamble). For

the above analyses, the EPA compared the environmental benefits and
corresponding costs that are expected to be achieved under various
control options to the environmental benefits and corresponding costs
that are expected to be achieved under the baseline.

A. Review of Control Technology

    Prior to promulgation of the MSW landfills NSPS (40 CFR part 60,
subpart WWW) in 1996, we conducted a review that identified the
existing types of emission control systems being used and the
corresponding emission reductions that were being achieved in practice.
Based on that evaluation, we determined BSER to be: (1) A well designed
and well operated landfill GCCS and (2) a control device capable of
reducing NMOC in the collected gas by 98 percent by weight (56 FR
24468, May 30, 1991 and 61 FR 9914, March 12, 1996). For BSER, we set
design and operating standards for the gas collection system and set an
emission limit for the control system. Then, we established a schedule
for installing and then expanding the GCCS based on the landfill's
design capacity (2.5 million megagrams and 2.5 million cubic meters)
and the estimated NMOC emissions rate (50 Mg/yr).
    The current technology review shows that the same types of
collection and control systems reviewed in 1996 (see Docket ID No. A-
88-09) continue to be prominently used to reduce landfill gas emissions
and the design and operational standards promulgated in 1996 continue
to be robust. Section VI of this preamble discusses our findings
resulting from consideration of potential revisions affecting the
criteria and schedule for installing and then expanding the GCCS. We
undertook this evaluation to determine if the thresholds associated
with BSER established in 1996 are still relevant today, ``taking into
account the cost of achieving such reduction and any non-air quality
health and environmental impact and energy requirements'' in accordance
with CAA section 111(a)(1).
    In 1996, the EPA set design and operational standards in subpart
WWW for the GCCS and an emission limit for the control device (61 FR
9907; March 12, 1996).\6\ Subpart WWW established design criteria for
both horizontal and vertical collection systems because both types of
systems are used. The criteria ensure that owners and operators design,
construct, and operate gas collection systems to maximize collection
and minimize emissions of landfill gas. Landfill GCCS designed
according to these criteria are expected to, at a minimum: (1) Be
capable of handling the maximum gas generation rate, (2) have a design
that provides for monitoring and adjusting the operation of the system,
(3) be able to collect gas effectively from all areas of the landfill
that warrant control, and (4) be expandable through the addition of
further collection system components to collect gas from new areas of
the landfill as they require control. Within 1 year of reaching or
exceeding an NMOC emission rate of 50 Mg/yr, landfill owners and
operators must submit (or update in the case of modification or
reconstruction) a collection and control system design plan prepared by
a professional engineer to the EPA or delegated authority for approval.
---------------------------------------------------------------------------

    \6\ In developing the current NSPS, the EPA determined that in
order to set a performance standard such as a collection efficiency
for the gas collection system it would be necessary to quantify the
landfill gas available for collection in comparison to the amount
collected and that it was not technically feasible to measure the
amount of gas available for collection. On that basis, the EPA
concluded that it was necessary to establish a design and operation
standard for the gas collection system (56 FR 24484, May 30, 1991).
---------------------------------------------------------------------------

    Gas collection system technology review. Our review shows that a
gas collection system comprising gas collection wells, horizontal or
vertical piping, and blowers continues to be the most common technology
used to collect landfill gas, regardless of whether a landfill is
complying with subpart WWW, state or local regulations, or voluntarily
controlling landfill gas for other reasons. Landfills continue to
collect landfill gas using gas collection systems that are similar to
the types of systems described in the background information of the
1996 landfill NSPS and emission guidelines proposal.\7\ As of 2013,
hundreds of landfills have installed collection systems to comply with
subpart WWW. The EPA is also aware that many landfill owners and
operators have installed collection systems on a voluntary basis. As of
2013, approximately 500 landfills voluntarily collect and control
landfill gas using the same technologies required by subpart WWW. The
EPA estimated this number by comparing the list of landfills that are
modeled to have installed a GCCS in 2014 in the NSPS/EG dataset to the
list of landfills that are reported to have a GCCS installed in the
LMOP database. See section V.B of this preamble for a discussion of the
dataset of landfills and corresponding model that the EPA used to
examine the potential impact of changes to the landfills NSPS. The LMOP
database is a voluntary national database of landfills and landfill gas
energy projects, including information on which landfills have a GCCS
in place.
---------------------------------------------------------------------------

    \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).
---------------------------------------------------------------------------

    Landfill owners and operators collect landfill gas for a variety of
reasons: To control odor, to minimize fire and explosion hazards, to
recover landfill gas to be used for energy recovery, to sell carbon
credits, and to comply with local, state, or federal air quality
standards. Landfill owners and operators are motivated to design and
operate their landfill gas collection systems to efficiently collect
and control landfill gas and they continue to install a gas collection
system comprising gas collection wells, horizontal or vertical piping,
and blowers to collect and control landfill gas.
    Gas collection system as BSER. For this NSPS review, the EPA is
proposing that the combination of design and operational criteria in
subpart WWW continue to ensure that the collection system efficiently
collects landfill gas and that a gas collection and control system
meeting these criteria continues to represent BSER for MSW landfills
that commence construction, reconstruction, or modification after July
17, 2014. The EPA is also proposing that a combined design and
operation standard for the gas collection system remains the best
format for the rule. In developing subpart WWW, the EPA determined that
in order to set a performance standard such as a collection efficiency
for the gas collection system it would be necessary to quantify the
landfill gas available for collection in comparison to the amount
collected and that it was not technically feasible to measure the
amount of gas available for collection. On that basis, the EPA
concluded that it was necessary to establish a design and operation
standard for the gas collection system (56 FR 24484, May 30, 1991). The
EPA has not determined that the circumstances have changed so as to
require the establishment of a standard of performance for the gas
collection system. (CAA section 111(h)(3), 42 U.S.C. 7411(h)(3).)
Therefore, for the gas collection system, the EPA proposes to maintain
the design and operational standards in subpart WWW in subpart XXX.
    Gas control system technology review. As part of the BSER review
prior to promulgation of subpart WWW in 1996, we conducted a technology
review that identified the existing types of emission control systems,
emerging technologies, and the emission reductions achieved in

practice by those systems. Properly operated GCCS reducing NMOC by 98
percent by weight had been demonstrated on landfills of the size
affected by subpart WWW. The EPA selected a reduction of 98 percent as
the level representing BSER for control of landfill gas because this is
the level achievable by demonstrated technologies. Based on this
analysis, the EPA selected 98 percent reduction, expressed as a
performance level (i.e., a rate-based standard or percent control), as
the appropriate BSER-based standard. The EPA determined that this level
was reasonable considering costs, nonair quality health and
environmental impacts, and energy requirements.\8\ Subpart XXX,
therefore, requires all control devices to demonstrate 98 percent
reduction by weight of NMOC or an outlet concentration of 20 ppmvd of
NMOC, as hexane. Enclosed combustion devices have the option of
reducing emissions to 20 parts per million, dry volume.
---------------------------------------------------------------------------

    \8\ Air Emissions from Municipal Solid Waste Landfills--
Background Information for Final Standards and Guidelines, EPA-453/
R-94-021. EPA Office of Air and Radiation/Office of Air Quality
Planning and Standards, Emission Standards Division, December 1995,
page 2-79.
---------------------------------------------------------------------------

    Each of the estimated 1,000 gas collection systems in place today,
both required and voluntary, has an associated combustion device used
to control emissions of landfill gas. At a minimum, landfills employ a
flare to combust the gas. Both open and enclosed flares were determined
to be among BSER combustion devices and these technologies continue to
be used today. The following combustion controls can achieve at least
98 percent destruction of NMOCs and we propose that they continue to
represent BSER: Enclosed flares and incinerators, and devices that burn
landfill gas to recover energy, such as boilers, turbines, and internal
combustion engines. The EPA continues to believe that 98 percent
reduction is appropriate because this continues to be the level
achievable by demonstrated technologies. Current data are consistent
with 98 percent destruction. However, we request comment and additional
data on the NMOC destruction efficiency of incinerators and devices
that burn landfill gas to recover energy, such as boilers, turbines,
and internal combustion engines.
    Non-enclosed flares used at landfills meeting the criteria in 40
CFR 60.18(b) are thought to have destruction efficiencies similar to
enclosed flares and incinerators, and devices that burn landfill gas to
recover energy, such as boilers, turbines, and internal combustion
engines. However, in April 2012 the EPA conducted an external peer
review on flaring efficiency and made available to the public a draft
technical report, ``Parameters for Properly Designed and Operated
Flares.'' \9\ In this report, the EPA evaluated test data and
identified a variety of parameters that may affect flare performance
and that could be monitored to help assure good combustion efficiency.
Nevertheless, none of the flare performance data used in this report
comes from flares used at MSW landfills, and it does not provide any
new test data on non-assisted flare types, which, to our knowledge, are
the only non-enclosed flare type found in this source category. Thus,
while we have no new information to suggest that flares at MSW
landfills complying with 40 CFR 60.18(b) will not achieve at least 98
percent destruction of NMOCs (and methane), we solicit comments and
additional information on flare performance specifically for this
source category in order to determine whether non-enclosed flares
continue to represent BSER for new landfills. Examples of information
requested for this source category include: Prevalence of flaring;
number and types of flares used; waste gas characteristics such as flow
rate, composition and heat content; use of flare gas recovery and other
flare emission minimization practices; and existing flare monitoring
systems.
---------------------------------------------------------------------------

    \9\ U.S. EPA, Parameters for Properly Designed and Operated
Flares, Report for Flare Review Panel, April 2012. http://www.epa.gov/ttn/atw/flare/2012flaretechreport.pdf.
---------------------------------------------------------------------------

    Gas control system as BSER. Based on the above, for this stage of
the NSPS review, the EPA has determined that a control system designed
and operated within the parameters demonstrated in the performance test
to reduce NMOC (and, in turn, methane) by 98 percent by weight or
reduction to 20 parts per million by volume, continues to represent
BSER for controlling landfill gas emissions. Therefore, the EPA
proposes in subpart XXX to maintain the current performance standard
from subpart WWW for the gas control system.
    Other current technologies. The EPA is also considering emission
control technologies or practices other than GCCS that are currently in
place as part of its review. The EPA qualitatively evaluated the
emission reductions achieved by those systems in practice and also
considered whether such technologies or practices could be relied upon
in establishing a standard of performance under CAA section 111.
    The EPA reviewed several best management practices (BMPs) for GCCS
that may achieve greater reductions in landfill gas emissions than a
well designed and well operated system alone. The EPA reviewed these
BMPs to determine if and how they could be incorporated into subpart
XXX in conjunction with the current performance-based standard.
    One BMP the EPA considered was collecting landfill gas from
leachate removal systems in order to control landfill gas that exists
below the waste mass along the bottom of the landfill. The EPA is aware
of landfills with leachate recirculation systems that have connected
the landfill gas collection system and leachate collection system;
however, references suggest that connection of these systems is not
common at landfills that do not employ leachate recirculation.\10\ The
efficiency of capturing LFG emissions through this BMP depends on the
efficiency of both the gas collection system and the leachate
recirculation system. Proposed 40 CFR 60.762(b)(2)(i)(D) recognizes
that leachate collection components may be part of a site-specific
collection and control system design plan. Because the design plan is
not prescriptive and instead contains design and operational standards
that are site-specific, the design plan has the flexibility to include
collection of landfill gas from leachate collection systems. However,
since we do not currently have sufficient information on the efficacy
of collecting gas from leachate removal systems in circumstances that
do not include leachate recirculation and since the use of leachate
recirculation is not prevalent in the landfill industry, the EPA does
not currently consider this BMP to be part of BSER for controlling
landfill gas, including methane, emissions. The EPA does, however,
request comments on the efficacy and costs of enhancing gas collection
systems to collect LFG from leachate removal or storage systems. The
EPA also requests comment on the types of landfills currently
collecting gas from leachate removal systems and the specifics of the
gas collection systems used in practice. The EPA will use this
information to evaluate if and when the use of an enhanced gas
collection system that collects landfill gas from the leachate removal
system may be appropriate.
---------------------------------------------------------------------------

    \10\ SCS Engineers, Technology and Management Options for
Reducing Greenhouse Gas Emissions. Prepared for California
Integrated Waste Management Board. Prepared by SCS Engineers. April
2008.
---------------------------------------------------------------------------

    Another BMP the EPA considered is requiring a gas collection system
to prevent waterlogged wells, perhaps

through the use of leachate removal pumps. Leachate and condensate can
accumulate in collection wells, blocking landfill gas capture. Because
a flooded well cannot collect gas, fixing a flooded well would have a
high emission reduction potential. Wellhead operating parameters in
proposed subpart XXX require that each owner or operator of an MSW
landfill either operate the collection system with a negative pressure
at each wellhead or, in areas with a geomembrane or synthetic cover,
establish acceptable pressure limits in the design plan. These
performance standards would help identify any inoperable wells
resulting from flooding. The proposed surface emissions monitoring
would also identify any elevated methane levels resulting from an
inoperable well. The EPA has determined that the operating requirements
in proposed subpart XXX provide a sufficient system to detect and
correct waterlogged wells and thus ensure that the gas collection
system is well operated.
    The EPA does not currently consider requiring that the gas
collection system be operated in such a way as to prevent waterlogged
wells, rather than requiring that the wells be monitored so as to
identify any such wells, to be BSER. Nonetheless, the EPA requests
comment on whether the current combination of wellhead monitoring and
surface emission monitoring is sufficient for identifying inoperable
wells, especially in cases where wells have been installed for a
significant amount of time. If the proposed monitoring systems are
believed to be deficient for identifying flooded wells, the EPA also
asks for comment on whether any additional recordkeeping, such as
periodic measurement of liquid levels in gas wells, might be useful in
identifying flooded wells that are not collecting gas.
    The EPA also considered a BMP of requiring redundant seals and
enhanced sealing materials on wellheads. One study includes a forward-
looking infrared (FLIR) survey suggesting that landfill gas wellheads
and other surface penetrations present high potential for concentrated
leaks of organic compounds.\11\ The use of advanced seals at wellheads
may help to ensure that the well can apply sufficient vacuum to the
landfill to facilitate gas extraction while preventing leaks of
landfill gas to the atmosphere.
---------------------------------------------------------------------------

    \11\ ARCADIS. Quantifying Methane Abatement Efficiency at Three
Municipal Solid Waste Landfills. Prepared for USEPA/ORD. January
2012.
---------------------------------------------------------------------------

    Proposed subpart XXX requires the preparation of a site-specific
design plan by a professional engineer, which must be approved by the
EPA or a delegated authority. Because the design plan is not
prescriptive and instead contains design and operational standards that
are site-specific, the design plan has the flexibility to determine the
appropriate number or type of seals in order to accommodate the
conditions and climates at different landfills. The EPA believes that
this site-specific approach is preferable to specifying the use of a
particular number of seals. This site-specific approach also provides
for continued flexibility for future design plans to incorporate new
sealing materials that may be more efficient than those currently
available today. The design plan, coupled with wellhead and surface
monitoring requirements, ensures that leaks from wells are minimized.
    With this proposal, the EPA is clarifying that all cover
penetrations must be checked during quarterly surface monitoring and
this clarification would apply to checking around each wellhead for any
elevated emission levels. Proposed subpart XXX requires corrective
action for any surface monitoring reading over 500 ppm. Finally, the
EPA is taking comment on tighter traverse patterns for surface
monitoring, coupled with more rigorous surface maintenance activity, as
another level of protection against leaks from improperly sealed wells.
    Further, one reference indicates that many engineers already
require two and sometimes three seals in a well when preparing design
plans for GCCS. For all of these reasons, the EPA believes that a site-
specific approach is more effective than prescribing the use of a
particular number of seals or the use of a particular type of sealing
material. As a result, at this point in its review, the EPA has
determined that the use of advanced seals is not a component of BSER.
The EPA, nevertheless, requests comment on whether the use of advanced
seals should be a component of BSER.
    The EPA also reviewed several emerging technologies that may
achieve additional landfill gas emission reductions. The EPA evaluated
whether the technology is adequately demonstrated and the extent to
which the technology could be applied to new landfills.
    The EPA considered a number of technologies that increase the
methane oxidation rate of the landfill, thereby reducing the amount of
methane that could escape through the surface of the landfill. Co-
oxidation of NMOC has been observed during use of these alternative
landfill cover materials, which has the potential to reduce odors and
toxic air pollutants.\12\ Oxidative covers, including biocovers, use
methanotrophic bacteria to oxidize methane into water, carbon dioxide,
and biomass. A biocover is an additional layer of final cover that is
typically made of two layers, a permeable layer to evenly distribute
the landfill gas to the oxidation media, and a layer of oxidation media
typically made of soil, compost, or other porous media. While these
innovative final cover practices at MSW landfills have the potential
for achieving a moderate amount of methane emission reductions, final
cover practices are currently addressed under Subtitle D of the
Resource Conservation and Recovery Act (RCRA) and not under the CAA. As
a result, the EPA does not currently consider them to be BSER; however,
research indicates that biocovers may help to reduce emissions of
methane, a primary constituent of landfill gas.
---------------------------------------------------------------------------

    \12\ U.S. EPA. Available and Emerging Technologies for Reducing
Greenhouse Gas Emissions from Municipal Solid Waste Landfills. June
2011.
---------------------------------------------------------------------------

    Another method for increasing the oxidation rate is to route
passively vented landfill gas through a vessel containing methane-
oxidizing media, commonly referred to as a biofiltration cell.
Biofilters have been tested for use at landfills over only the past 10
to 15 years, and, although they may achieve moderate to high reductions
in uncontrolled methane emissions, we cannot conclude at this time that
these systems have been adequately demonstrated, as we explain
below.13 14 Biofiltration cells are feasible for use only at
small landfills or landfills with passive gas collection systems due to
the size of the biofiltration bed required to treat the mixture of air
and landfill gas. New landfills are expected to be large and have
active gas collection systems to comply with the requirements in the
proposed subpart XXX. In addition, due to the nature of passive gas
collection systems, this technology lacks the ability to control and
monitor the oxidation of methane in the landfill gas.\15\
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    \13\ Buske, D. and M. Lannan. The Biofilter Effect on Landfill
Gas Capture. 2009 SWANA Landfill Gas Symposium Proceedings.
    \14\ Gebert, J.; and Groengroeft, A., 2006, ``Performance of a
passively vented field-scale biofilter for the microbial oxidation
of landfill methane''. Waste Management Research 26: 399-407.
    \15\ USEPA. Available and Emerging Technologies for Reducing
Greenhouse Gas Emissions from Municipal Solid Waste Landfills. June
2011. http://www.epa.gov/nsr/ghgdocs/landfills.pdf.
---------------------------------------------------------------------------

    No data exist on the long-term performance, effectiveness, or
maintenance requirements of these

systems.16 17 18 For these reasons, these methane oxidation
technologies were not considered to be BSER. However, the EPA is
requesting information about application of these technologies to
better understand these characteristics for full-scale use of biocovers
and biofilters. The EPA is seeking information and data about the long-
term performance, effectiveness, and/or maintenance requirements of
full-scale use of biocovers and biofilters, as well as comment on
appropriate mechanisms to monitor the performance of these
alternatives. Comment is also requested on biocover parameters and
their effect on oxidation. Such parameters may include depth, soil
characteristics, measurement, and their effect on percent oxidation.
---------------------------------------------------------------------------

    \16\ Ibid.
    \17\ Abichou, T, J. Chanton, D. Powelson, ``Field Performance of
Biocells, Biocovers, and Biofilters to Mitigate Greenhouse Gas
Emissions from Landfills,'' State University Systems of Florida,
Florida Center for Solid and Hazardous Waste Management March 2006.
    \18\ Yazdani, R, and Imhoff, P. Contractor's report to
CalRecycle: Biocovers at Landfills for Methane Emissions Reduction
Demonstration. October 2010.
---------------------------------------------------------------------------

B. What data and control criteria did the EPA consider in evaluating
potential changes to the timing of installing, expanding, and removing
the GCCS?

    To examine the potential impact of changes to the timing of
initiating landfill gas collection and control, the EPA developed a
dataset of information for existing and new landfills, as described
below, and applied a model to assess when controls were needed under
the baseline control scenario as well as various regulatory options.
Each regulatory option assessed variations in the design capacity and
emission rate thresholds, as well as changes to the initial lag time
and expansion lag time. The ``initial lag time'' is the time period
between when the landfill exceeds the emission rate threshold and when
controls are required to be installed and started up (30 months in
subpart WWW). The ``expansion lag time'' is the amount of time allotted
for the landfill to expand the GCCS into new areas of the landfill (5
years for active areas and 2 years for areas that are closed or at
final grade in subpart WWW).
    The EPA created a dataset of information for existing and new
landfills, which included landfill-specific data such as landfill open
and closure year, landfill design capacity, landfill design area, and
landfill depth. The creation of the landfill dataset is detailed in the
docketed memorandum, ``Summary of Landfill Dataset Used in the Cost and
Emission Reduction Analysis of Landfills Regulations. 2014.''
    The EPA used attributes of these existing landfills to develop
model landfills to represent new landfills opening in the first 5 years
after subpart XXX is proposed (2014-2018). The model future landfills
were developed by evaluating the most recently opened existing
landfills and assuming that the sizes and locations of landfills
opening in the future would be similar to the sizes and locations of
landfills that opened in the last 8 years with complete data (2003-
2010).
    The EPA then incorporated technical landfill parameters from this
dataset, such as landfill size, annual waste acceptance rate, and open
year, into a model in order to estimate when each landfill would
install GCCS under various regulatory options. This model used a first-
order decay equation to model the landfill gas emissions (i.e., NMOC
and methane) from each landfill for 50 years following the effective
date of subpart XXX.
    The EPA programmed a Microsoft[supreg] Access database to calculate
the cost and emission impacts associated with different regulatory
options (hereinafter referred to as the ``model''). To determine when
landfills exceeded regulatory emission thresholds, the model uses Tier
1 default values from subpart WWW for the methane generation potential
(L0) and the methane generation rate (k), but uses the NMOC
concentration in ``Compilation of Air Pollutant Emission Factors (AP-42
\19\)'' for determining when landfills would meet the regulatory NMOC
emissions threshold. The Tier 1 default values in subpart WWW for
L0 and k are conservatively high for the purpose of
estimating actual emissions; therefore, they are used only for
estimating uncontrolled emissions to determine when landfills could
exceed the threshold and be required to install controls. For the
average NMOC concentration, the model uses the default value specified
in AP-42. Subpart WWW allows the use of Tier 2 tests to determine NMOC
concentration, and industry experience suggests the majority of
landfills have conducted Tier 2 tests and obtained estimates that are
consistent with the AP-42 NMOC value; thus, the AP-42 NMOC value was
deemed to be more representative than Tier 1 NMOC values for
determining when landfills would meet the regulatory NMOC emissions
threshold for installing a landfill GCCS.
---------------------------------------------------------------------------

    \19\ U.S. EPA, AP-42, Fifth Edition, Compilation of Air
Pollutant Emission Factors, Volume 1: Stationary Point and Area
Sources. 1995. http://www.epa.gov/ttnchie1/ap42/.
---------------------------------------------------------------------------

    When modeled landfill gas emissions for a particular landfill
exceeded the emission rate threshold, the EPA assumed that collection
equipment was installed and started operating at the landfill after the
initial lag time specified in each option. The EPA also assumed that as
the landfill was filled over time, the landfill would expand the GCCS
into new areas of waste placement in time intervals that coincide with
the expansion lag time specified in each option.
    To determine when controls may be capped or removed, and to
calculate the amount of landfill gas, NMOC, and methane collected under
each option, the model uses L0, k, and NMOC values from AP-
42 instead of the Tier 1 default values. To determine when control
systems may be removed, subpart WWW requires landfills to conduct
actual measurements of the collected gas flow rate and NMOC
concentration. Because the AP-42 default values are more representative
of actual emissions from landfills than Tier 1 values, they are more
useful for predicting when a landfill would be able to remove its
control system. For the same reason, AP-42 values were used to
determine actual annual emissions reductions achieved by control
systems.
    To estimate the costs of each regulatory option, the EPA
incorporated the estimated landfill gas recovery rates from the first-
order decay equation and an estimated well field acreage into a set of
cost equations based on EPA's Landfill Gas Energy Cost Model (LFGcost),
version 2.3, which was developed by EPA's LMOP. (LFGcost estimates gas
collection, flare and energy recovery system capital, operating, and
maintenance costs.) The EPA also collected data on monitoring and
testing costs such as initial performance tests, subpart WWW Tier 1 and
Tier 2 calculations, and quarterly surface monitoring that were not
provided in the LFGcost model.
    The capital costs are all presented in year 2012 dollars and
annualized using an interest rate of 7 percent over the lifetime of the
equipment (typically 15 years), or in the case of drill mobilization
costs, the length of time between each wellfield expansion. These
annualized capital costs were added to the annual operating and
maintenance costs estimated by LFGcost. The annualized cost includes
capital requirements related to the purchase, installation, operation
and maintenance of GCCS, and costs related to testing and monitoring
requirements.

    For certain landfills that were expected to generate revenue by
using the LFG for energy, the EPA also estimated LFG energy recovery
rates and associated costs to install and operate the energy recovery
equipment as well as the revenue streams from the recovered energy.
These revenues were subtracted from the annualized capital and
operating and maintenance costs at each landfill in order to obtain a
net cost estimate for each option in each year. The emission reduction
and cost and revenue equations and assumptions are detailed in the
docketed memorandum, ``Methodology for Estimating Cost and Emission
Impacts of MSW Landfills Regulations. 2014.''
    Often the EPA examines the impacts of NSPS at 5 years after rule
implementation; however, the EPA selected 10 years for this landfills
NSPS review, 2023. Due to the emission characteristics of new landfills
that begin to accept waste in 2014 or after and the applicability
provisions of the NSPS, 5 years would not provide a representative
population of landfills for evaluating alternative standards, and in
fact none of the modeled landfills would be expected to have installed
controls by year five. Landfills do not become subject to the control
requirements of the NSPS on the date that they begin operation.
Instead, landfills exceeding the design capacity threshold become
subject to control requirements 30 months after the emissions exceed
the NMOC emission threshold. It may take well over 5 years for a newly
constructed landfill to exceed the NMOC threshold, depending on the
rate of waste acceptance and other site-specific factors. Therefore,
evaluating the impacts of the rule at 5 years would significantly
underestimate the impacts that subpart XXX may have on affected
facilities.
    The EPA recognizes that landfills have a unique emissions and
emission control timeline over their lifetime, compared to other
stationary sources of emissions. The quantity of emission reductions
achieved and the costs to achieve those reductions will vary depending
on where each landfill is in its lifecycle. By year 10 (year 2023),
landfills in this analysis are further along in their lifecycle than
they would be at year five and over half of the modeled landfills have
installed controls, incurred costs, and achieved emission reductions
under several options the EPA considered in its review of the NSPS.

C. What control options did the EPA consider?

    When determining which control options would represent BSER, the
EPA ran many permutations of various control options. Some options
adjusted a single threshold in isolation; for example, reducing the
NMOC emission threshold while keeping the design capacity threshold
constant, or conversely, reducing the design capacity threshold while
keeping the NMOC emission threshold constant. Other options adjusted
multiple control parameters simultaneously, taking into account the
relationship between the parameters. For example, recognizing that NMOC
emissions are a function of waste-in-place, some options that
significantly reduced the NMOC emission threshold also reduced the
design capacity thresholds to avoid situations where the NMOC emission
threshold would be exceeded long before the design capacity threshold.
Other options increased the design capacity threshold while reducing
the NMOC emission threshold by relatively small increments in order to
minimize the reporting-only burden that would be imposed on landfills
that had exceeded the design capacity threshold, but not the NMOC
emission threshold, and would therefore be reporting, but not
controlling.
    In addition to adjusting applicability and emission control
thresholds, other model runs varied the initial and/or expansion lag
times. These variations estimated the impacts of requiring landfill
owners or operators to install gas collection systems more quickly
after crossing each applicable NMOC emission threshold. Specifically,
some model runs assessed the impacts of reducing the initial lag time
from 30 months (modeled as 3 years for the purpose of this analysis, as
discussed in the docketed memorandum ``Methodology for Estimating Cost
and Emission Impacts of MSW Landfills Regulations. 2014'') to 2 years.
Model runs varying the expansion lag time were also run. For expansion
lag times, subpart WWW allows 2 years after initial waste placement in
closed areas and 5 years after initial waste placement in active areas
of the landfill. As a result, the actual expansion lag time varies by
landfill depending on how quickly expansion areas are filled and
closed. Modern large landfill designs tend to expand the collection
system 5 years after initial waste placement in active areas of the
landfill. Based on input received during public outreach, most modern
large landfills do not reach final grade within 2 years and a majority
of landfills are complying with the 5 year provision. Therefore, a 4-
year expansion lag time was assumed to represent the baseline, as
discussed in more detail in the docketed memorandum ``Methodology for
Estimating Cost and Emission Impacts of MSW Landfills Regulations.
2014.'' A shorter expansion lag time of 2 years after initial waste
placement was examined as an alternative regulatory option. Some model
runs evaluated the impacts of reducing both the initial and expansion
lag times in parallel and other model runs evaluated the impacts of
reduced emission and/or design capacity thresholds in conjunction with
reduced initial and/or expansion lag times.
    Preliminary results of the model runs showed that the current set
of design capacity and NMOC emission threshold parameters in subpart
WWW was the most cost effective option in year 2023. Options that
reduced the NMOC emission threshold slightly, either in isolation or in
conjunction with a reduction in the design capacity threshold had only
a slightly higher cost effectiveness than the baseline. See the
docketed memorandum ``Cost and Emissions Impacts Resulting from the
Landfills NSPS Review. 2014'' and the docketed item ``Modeling Database
Containing Inputs and Results of Proposed Revisions to MSW Landfill
NSPS. 2014.'' Options that reduced the initial and/or expansion lag
times to 2 years were typically less cost effective than the options
that reduced the NMOC emission threshold.
    Based on the results of the preliminary analysis, the EPA presented
different model runs during Federalism consultations and small entity
outreach that represented the range of variation in both the threshold
and lag time parameters. For the options presented, Small entity
representatives (SERs) and Federalism consultation participants
provided feedback to the EPA, which included implementation concerns
with varying certain parameters as part of this NSPS review, as
discussed in the following section. The EPA took these concerns into
consideration when developing the set of proposed options in this
action.

D. What are the implementation concerns with changing the design
capacity criteria?

    Options that increase the design capacity threshold provide some
opportunities for reduced reporting burden; however, these options also
introduce the potential to miss emission reduction opportunities at
certain landfills that exceed the NMOC

emission thresholds but do not meet the design capacity thresholds.
Further, installation of GCCS at landfills with design capacities
between 2.5 and 3.0 million Mg are well demonstrated. According to the
LMOP database, there are more than 50 landfills out of 70 in this size
range that have installed GCCS.
    Options that reduce the design capacity threshold without also
lowering the NMOC emission threshold would create additional reporting
and permitting burden without any additional environmental benefit.
These types of options would not change the number of landfills
required to control emissions, but they would increase the number of
landfills required to obtain an operating permit and also increase the
number of landfills required to complete Tier 1 or Tier 2 emission
calculations and reports.
    When the EPA promulgated the 2.5 million Mg design capacity
threshold in 1996, we considered the impact on small entities based on
public comment (61 FR 9910). Today, small entities still tend to own
smaller sized landfills, whereas larger entities tend to own larger
regional landfills. Approximately 10 percent of the landfills subject
to subpart WWW or the MSW landfills state or federal plan implementing
subpart Cc are owned by small entities. Further, the cost burden for
installing a collection and control system is more significant for
small landfills, which are more often owned by small entities, than
larger landfills. Certain costs to construct the gas collection system
(e.g., flat fees for drill rig mobilization, and monitoring and
construction costs) remain relatively constant regardless of the size
of the landfill.
    For these reasons, the EPA is not proposing any changes to the
current design capacity threshold of 2.5 million Mg and 2.5 million
m\3\.

E. What are the implementation concerns with reducing the NMOC
threshold?

    The EPA recognizes that NMOC emissions are site specific, varying
widely from landfill to landfill and understands that a majority of
landfills currently affected by subpart WWW conduct Tier 2 testing in
order to refine their NMOC emission estimates before installing a GCCS.
    Lowering the NMOC emission threshold would result in earlier GCCS
installations, 13 percent more emission reductions, and a dollar-per-Mg
cost to control NMOC that is higher than the baseline ($6,000/Mg NMOC
vs. $4,400/Mg NMOC). Despite these higher costs, the EPA also
recognizes the value of reducing methane emissions ($1.50/Mg
CO2e vs. $1.10/Mg CO2e at baseline) that are
associated with a lower NMOC emission threshold, as discussed in
sections III and VI.B of this preamble. Based on these considerations,
among others, the EPA is proposing to reduce the NMOC emission
threshold from 50 Mg/yr to 40 Mg/yr. See section VI.B of this preamble
for more details.

F. What are the implementation concerns with shortening the initial or
expansion lag times?

    The emission reductions achieved by reducing the initial or
expansion lag time are affected by the size of the landfill, waste
placement patterns, and annual acceptance rates. For example, the size
of the landfill and the filling cycle affects how much and when
emission reductions would be achieved. Based on comments received from
SERs and Federalism consultation participants, modern landfill designs
typically do not reach final grade before 7 years. Because the
landfills NSPS allows two options for expanding the GCCS (2 years after
initial waste placement in closed areas and 5 years after initial waste
placement in active areas), any reduction to the 2 year lag time for
closed areas would not likely achieve any actual additional reductions
from these larger landfills because the majority of landfills are
complying with the 5-year allowance period instead of the 2-year
allowance period. Modifying the 5-year provision may also have a
limited actual impact on emission reductions. Many landfills in wet
climates install wells ahead of the 5-year schedule for odor or energy
recovery purposes. When examining the effects of shortening the lag
times, the emission reductions vary over the time period considered. To
visually observe how reducing the lag times affects emissions and
reductions over the 10-year period following proposal, see the charts
comparing emissions from reduced lag times in the docketed memorandum,
``Cost and Emissions Impacts Resulting from the Landfills NSPS Review.
2014.''
    When isolating the timeframe for initial GCCS installation from the
other control criteria, modeling showed that the reductions in year
2023 are lower than those estimated to be achieved under the current
baseline. Although the initial GCCS would be installed earlier, for
example in year 2020, it would also be designed slightly smaller (i.e.,
a smaller number of wells) than a GCCS installed in a later year. By
2023, the system would not have been expanded yet, thus, the total
amount of emission reductions achieved in 2023 will be less than the
baseline until the system is expanded in 2024.
    Reducing the expansion lag time would achieve a short period of
modeled reductions during every expansion cycle because the GCCS would
be expanded one year earlier. Emission reductions in year 2023 would be
approximately 27 percent higher than an option that did not shorten the
expansion lag time. However, when considered over a 10-year period, the
additional emission reduction would be approximately 8 percent.
    Small entity representatives and Federalism consultation
participants expressed concern about the potential shortening of lag
times. For details, refer to the docketed report ``Summary of Small
Entity Outreach. 2014.''
    According to the commenters, reduced lag times would result in the
installation of more GCCS equipment in active fill areas. Wells located
in these areas are more frequently damaged as a result of daily filling
operations and the movement of equipment. Damaged wells must be
repaired with well extensions and/or redrilling of wells. In addition,
waste in active fill areas undergoes significant settlement. This
settlement affects the alignment of gas header equipment, requiring
more frequent repairs, troubleshooting, and replacement of equipment.
These repairs can add a significant cost to the construction and
operation of a GCCS that is not currently accounted for in the LFGcost
estimates and also increase the amount of system downtime.
    In addition to the implementation concerns, reducing the lag times
would require more frequent mobilization of drill rig equipment,
purchase of GCCS infrastructure, and system repairs, which could lead
to higher costs. In year 2023, the dollar-per-Mg cost to reduce the
initial and/or expansion lag times in conjunction with reducing the
NMOC threshold are higher than the options that do not adjust the lag
times ($6,900 to $11,300/Mg NMOC vs. $6,000/Mg NMOC). This higher cost
is due in part to the timing of the first round of wellfield expansions
at these new landfills, many of which were modeled to expand their
systems in 2023, and thus incurring additional costs in that year to
operate both the initial GCCS and the first set of expansion wells.
    Small entity representatives and Federalism consultation
participants raised several practical concerns with reducing the
expansion lag time. Reducing the expansion lag time would result in
more wells located in active fill areas because more of the face of the
landfill is active after only 2 years of waste acceptance and the
landfill owner

or operator must add wells into these active areas sooner.
    In addition, active fill areas are still in the aerobic phase of
waste decomposition. Installing wells in areas with high oxygen levels
increases the chance of subsurface fires. It also leads to more
frequent exceedances of the current wellhead monitoring standards for
oxygen. In these cases the landfill owner or operator would also be
unlikely to request a higher operating value for oxygen because they
would have difficulty meeting the two criteria in proposed 40 CFR
60.763(c) for a higher operating value demonstration: A higher
operating value must not cause fires and must not significantly inhibit
anaerobic decomposition by killing methanogens. Neither of these
criteria would apply to wells located in active fill areas.
    Horizontal LFG collection wells may provide some relief to these
implementation concerns that were raised by the SERs, while also
allowing for the wells to be installed more quickly after the waste is
placed in the landfill. These types of wells consist of perforated pipe
in gravel-filled trenches constructed within the waste mass as an
active area is filled. The wellheads are installed remotely outside of
the active fill area to allow landfill owners/operators to monitor the
wells. Although the horizontal collection infrastructure is installed
as the waste is placed in the fill area, the collectors are not brought
online under an active vacuum until a sufficient refuse layer has been
placed on top of the collectors. This time period is necessary in order
to prevent air infiltration in the landfill. However, this time period
is often shorter than the timeframe needed to install vertical wells,
and can be as short as a few months after refuse is buried.\20\
---------------------------------------------------------------------------

    \20\ Barlaz et al., Controls on Landfill Gas Collection
Efficiency: Instantaneous and Lifetime Performance 59 J. Air & Waste
Mgmt. Ass'n 1399, 1402-03 (Dec. 2009).
---------------------------------------------------------------------------

    The EPA is aware of several horizontal collector installations,
including several landfills in California \21\ and 18 different
landfills that reported using horizontal collectors in the voluntary
data collection effort for this rulemaking (see ``Summary of Landfill
Dataset Used in the Cost and Emission Reduction Analysis of Landfills
Regulations. 2014'').
---------------------------------------------------------------------------

    \21\ SCS Engineers, Technology and Management Options for
Reducing Greenhouse Gas Emissions. Prepared for California
Integrated Waste Management Board.
---------------------------------------------------------------------------

    The shorter length of time associated with bringing horizontal
collectors online can be especially important at landfills employing
liquids recirculation techniques or located in wetter climates, given
the higher LFG generation rates at those sites (see section V.G of this
preamble). Bringing these collectors online more quickly and more
proactively addresses odor concerns at landfills. These systems are
also useful in landfills that practice ``over-filling,'' where new
waste is placed on top of a section of the landfill that was capped
temporarily. SERs did express some implementation concerns with
horizontal collectors, indicating that these systems have a shorter
lifetime than vertical wells and require more frequent replacement.
    For the reasons presented in this section, the EPA is not proposing
to shorten the initial or expansion lag times from the lag times
codified in subpart WWW. However, the EPA requests comment on the
feasibility and potential benefits of reducing either or both of the
lag times. Specifically, the EPA requests comment on the practicality,
cost, and emission reduction implications of installing or expanding
the wellfield on active areas in a shorter timeframe. The EPA believes
that this may be appropriate since horizontal collector systems have
been installed at several landfills that were not in operation when the
NSPS was originally promulgated in 1996. The EPA also requests data
and/or comment on the potential emission reductions and corresponding
costs that could result from reduced lag times. The EPA also notes that
the cost analysis presented in section X of this preamble is based on
vertical wells and the EPA is interested in any comments and data that
address any differential in costs between these two types of systems.

G. Request for Comment on BSER

    The EPA is requesting comment on several items regarding BSER. EPA
is requesting comment on the proposed design and operational standards
for new sources that EPA believes are necessary to ensure a GCCS is
well designed and well operated. The EPA is requesting comment on
additional emission control technologies that are in place at
landfills--other than a GCCS as described here--that could be
considered BSER. We request descriptions of such systems, an indication
of their current use, data demonstrating emission reductions, and
corresponding costs of such systems. The EPA is also requesting comment
on whether a well designed and well operated GCCS in conjunction with
any of the technologies or practices discussed in section V.A of this
preamble should be considered to be BSER.
    The EPA is also taking comment on whether it should consider
reducing the design capacity threshold or initial lag times for
landfills that are located in a wet climate or that recirculate
leachate or add other liquids to the landfills to accelerate waste
decomposition. Wetter wastes decompose more quickly than drier wastes
and as a result generate more landfill gas in the short term.
Therefore, it may be appropriate to require these landfills to install
the gas collection system sooner, which SERs indicated is already
occurring in practice for landfills in wetter climates. Similarly,
smaller landfills in wetter climates, or those employing leachate
recirculation, may also generate earlier spikes in landfill gas
emissions that could exceed the NMOC threshold. Although these
landfills are exempt from proposed subpart XXX under the design
capacity threshold of 2.5 million Mg and 2.5 million cubic meters, if a
smaller design capacity threshold were adopted for these wet landfills,
more emission reductions may be achieved.
    If a separate set of thresholds and/or lag times were to apply to
these wet landfills, the EPA requests comment on how a wet landfill
might be defined. For example, a wet landfill could be defined as a
landfill that has precipitation of greater than 25 inches per year and/
or recirculates leachate (or other liquids).

VI. Rationale for the Proposed Changes Based on Review of the NSPS

    To determine which option to propose, the EPA considered the
emission reductions that are expected to be achieved under the criteria
in the baseline (subpart WWW), as well as emission reductions that
would be achieved under several control options more stringent than the
baseline.

A. What are the environmental impacts and costs associated with the
baseline?

    In this analysis, the baseline contains the same gas collection and
control requirements and thresholds (2.5 million Mg or 2.5 million
cubic meters and 50 Mg NMOC per year) that are in subpart WWW. For the
baseline, the initial lag time is 30 months; and the expansion lag time
is 2 years after initial waste placement in cells that are closed or at
final grade or 5 years after initial waste placement in active areas of
the landfill. These parameters are described in detail in section V of
this preamble.
    Table 2 of this preamble summarizes the impacts of the baseline for
year 2023. The table includes emission reductions for NMOC, methane,
and carbon dioxide equivalent (CO2e) and corresponding
annualized net costs based on the annualized control, testing,

and monitoring costs, and annual revenues from energy recovery (when
applicable), as discussed in section V.B of this preamble.

                                                 Table 2--Baseline Emission Reductions and Costs in 2023
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                Number of
  Number of      Number of      landfills      Annual net    Annual NMOC       Annual      Annual CO2e      NMOC cost      Methane cost      CO2e cost
  landfills      landfills    reporting but   cost ($2012)    reductions      methane       reductions    effectiveness    effectiveness   effectiveness
   affected     controlling        not            \a\          (Mg/yr)       reductions      (Mg/yr)          ($/Mg)          ($/Mg)          ($/Mg)
                               controlling                                    (Mg/yr)
--------------------------------------------------------------------------------------------------------------------------------------------------------
         17              8              9      2,708,000            610         94,800      2,371,000           4,400               29             1.1
--------------------------------------------------------------------------------------------------------------------------------------------------------
\a\ The annualized net cost ($2,708,000) is the difference between the average annualized revenue ($21,315,300) and the sum of annualized control cost
  ($23,956,900) and the average annualized testing and monitoring costs ($66,400).

    The baseline is estimated to require control at eight landfills in
2023, and achieve reductions of 610 Mg/yr NMOC, 94,800 Mg/yr methane
(2,371,000 Mg/yr CO2e). The annualized net cost is $2.7
million. The cost effectiveness of the baseline is estimated to be
$4,400 per Mg NMOC, and $29 per Mg methane ($1.10 per Mg
CO2e) if all of the control cost were attributed to each
pollutant separately.
    In this analysis, the EPA projects 21 new landfills would commence
construction, reconstruction, or modification between 2014 and 2018.
The basis of this projection is discussed in detail in the docketed
memorandum ``Summary of Landfill Dataset Used in the Cost and Emission
Reduction Analysis of Landfills Regulations. 2014.'' These 21 landfills
are projected to emit, 1,040 Mg/yr of NMOC and 161,600 Mg/yr of methane
in 2023 if the landfills had no emission controls in place. However,
the baseline is modeled to require 38 percent (8/21) of these projected
landfills to install emission controls by at least year 2023. In terms
of emissions, the baseline is expected to achieve 59 percent reduction
in estimated emissions from these landfills in 2023. Further, the eight
landfills installing controls under the baseline represent 77 percent
of the estimated total waste-in-place in 2023 from all 21 of the
projected landfills.
    The baseline allows landfills to remove the GCCS only after the
following criteria are met (1) the landfill is closed, (2) the landfill
has had the GCCS in operation for at least 15 years, and (3) three
successive tests for NMOC emissions are below the NMOC emission
threshold of 50 Mg/yr. Until the GCCS is removed, the landfill must
continue to operate the system in accordance with 40 CFR 60.763, which
includes wellhead monitoring and surface emissions monitoring to detect
and correct for any emission exceedances.

B. How did the EPA determine which control option to propose?

    When determining which control options would represent BSER, the
EPA considered several factors: The implementation concerns identified
in section V of this preamble; and the incremental emission reductions,
cost, and co-benefits that would be achieved beyond the baseline.
    The EPA compared the annualized net cost and emission impacts in
2023 of the various regulatory options to the annualized net costs and
emission impacts in 2023 of the baseline. The EPA analyzed numerous
iterations of alternate control and reporting thresholds and presented
potential control options to SERs and Federalism consultation
participants, as described in section V of this preamble. After
considering feedback from the SERs and Federalism consultation
participants, the EPA selected for consideration three regulatory
alternatives as presented in Table 3 of this preamble. Table 3 of this
preamble summarizes the incremental impacts of each control option,
when compared to the baseline. The table shows the emission reductions
and corresponding annualized net costs for NMOC and methane in 2023.

                                                             Table 3--Emission Reductions and Costs for Control Options in Year 2023
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                Number of      Number of                                Annual        Annual
                                                                landfills      landfills    Annual net  Annual NMOC    methane        methane        NMOC cost     Methane cost    Methane cost
                      Control parameters                         affected     controlling      cost      reductions   reductions    reductions     effectiveness   effectiveness   effectiveness
                                                                   \a\            \a\         (2012$)      (Mg/yr)     (Mg/yr)     (Mg CO2e/yr)       ($/Mg)          ($/Mg)      *  ($/Mg CO2e)
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
                                                              Baseline = 2.5 million Mg and m\3\, design capacity and 50 Mg/yr NMOC
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Baseline (2.5 design capacity/50 Mg/yr NMOC).................           17               8   2,708,000          610       94,800       2,371,000           4,400              29             1.1
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                             Incremental values versus the Baseline
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Option (3.0 design capacity/40 Mg/yr NMOC....................            0               3     471,000           79       12,300         307,600           6,000              38             1.5
Option (2.5 design capacity/40 Mg/yr NMOC....................            0               3     471,000           79       12,300         307,600           6,000              38             1.5
Option (2.0 design capacity/40 Mg/yr NMOC....................            1               3     472,700           79       12,300         307,600           6,000              38             1.5
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
\a\ Landfills are affected by the landfills NSPS based on design capacity. Once affected, they calculate and report emissions until they exceed the NMOC threshold, which triggers control
  requirements.

    Baseline. The baseline affects 17 new landfills, meaning that 17
landfills meet the design capacity thresholds and would have to report
their emissions during this period. Eight of these landfills would have
controls in place in

year 2023. The baseline values are compared to landfills' emissions
assuming that no GCCS are installed. This comparison to a no-control
scenario may overestimate both the costs and emissions reduction
resulting from implementation of subpart XXX due to other regulatory or
voluntary reasons for installing GCCS, as discussed below.
    The EPA is aware that some state or local ordinances require
landfill gas combustion for odor, safety, or methane control reasons.
For example, methane regulations in California \22\ require GCCS to be
installed at all landfills accepting waste after January 1, 1977,
having at least 450,000 tons of waste-in-place, and having a gas heat
input capacity threshold of 3.0 MMBtu/hr or greater to install GCCS.
The emission reductions from these programs could not be quantified for
the projected set of model landfills because the EPA cannot reliably
estimate where these future landfills will be installed.
---------------------------------------------------------------------------

    \22\ California Code of Regulations, title 17, subchapter 10,
article 4, subarticle 6, sections 95460 to 95476, Methane Emissions
from Municipal Solid Waste Landfills.
---------------------------------------------------------------------------

    Finally, based on data from LMOP, the EPA is also aware of
approximately 500 landfills that have voluntarily installed a gas
collection system that would not otherwise be required under federal
NSPS or emission guideline regulations (see section V.A of this
preamble for details). These systems may have been installed to recover
energy and generate revenue, including sale of electricity or landfill
gas as well as to create carbon credits. However, because it is not
known how many projected new landfills will voluntarily collect and
combust their gas in the absence of NSPS regulation, the reductions
associated with voluntary gas collection system installations were not
considered when establishing the reductions associated with the
baseline.
    Regulatory options. The EPA considered three regulatory options
more stringent than the baseline, as presented in Table 3 of this
preamble. Based on the characteristics of the projected landfills, all
three of the more stringent options would require a total of 11
landfills to install controls by 2023. Thus, 11 landfills would incur
costs and achieve emission reductions in 2023 under all of the more
stringent options, compared with eight landfills under the baseline.
    Although the overall difference in the number of landfills
requiring control in 2023 under the more stringent options is only
three landfills, it is important to note that each of these options
would require controls to be installed earlier than the baseline,
because lower NMOC emission thresholds would subject landfills to the
control requirements at an earlier date.
    Table 4 presents the number of landfills with control systems
installed, by year, for the baseline and options considered in this
analysis. Due to the 30-month initial lag time period, no controls are
anticipated to be installed prior to 2020 under any of the options
under consideration.

 Table 4--Total Number of New Landfills Projected To Control Landfill Gas Emissions in Each Year of the 10-Year
                                                Period, by Option
----------------------------------------------------------------------------------------------------------------
                                                 Number of landfills with  control systems installed
         Control parameters         ----------------------------------------------------------------------------
                                      2014-2019        2020            2021            2022            2023
----------------------------------------------------------------------------------------------------------------
Baseline 2.5/50....................            0               0               6               7               8
Option 3.0/40......................            0               3               6               7              11
Option 2.5/40......................            0               3               6               7              11
Option 2.0/40......................            0               3               6               7              11
----------------------------------------------------------------------------------------------------------------

    Emission reductions. Under all three of the options considered,
three additional landfills would be required to install controls in
2023 compared to the baseline. The reductions achieved under these
three options are the same because each option has the same NMOC
threshold trigger of 40 Mg/yr. The corresponding emission reductions in
2023 would be an additional 79 Mg/year NMOC, 12,300 Mg/year methane
(307,600 Mg/year CO2e) compared to the baseline. The wide
range in magnitude of emission reductions among pollutants is due to
the composition of landfill gas: NMOC represents less than 1 percent of
landfill gas, while methane represents approximately 50 percent.
CO2e is an expression of methane in terms of the carbon
dioxide equivalents, given the methane global warming potential (GWP)
of 25.\23\ Each of these options represents approximately a 13 percent
reduction beyond the baseline.
---------------------------------------------------------------------------

    \23\ IPCC Fourth Assessment Report (AR4), 2007. Climate Change
2007: The Physical Science Basis. Contribution of Working Group I to
the Fourth Assessment Report of the Intergovernmental Panel on
Climate Change [Core Writing Team, Pachauri, R.K and Reisinger, A.
(eds.)]. IPCC, Geneva, Switzerland, 104 pp.
---------------------------------------------------------------------------

    Cost. Under both options 2.5/40 and 3.0/40, the incremental annual
cost would be $471,000. The cost is identical for these two options
because all of the projected new landfills that exceed the NMOC
thresholds and install controls by 2023 have a design capacity greater
than 3.0 million Mg. Based on the characteristics of recently
constructed landfills, it is likely that most new landfills will be
larger sites. The incremental annual cost of option 2.0/40 is $2,700
higher, at $472,700 due to additional reporting costs for one landfill
that is projected to exceed the lowered design capacity threshold but
not the NMOC threshold. All of these options represent approximately 17
percent in additional costs beyond the baseline.
    In terms of cost effectiveness, the overall dollar-per-Mg cost for
NMOC reductions is $4,400 per Mg NMOC under the baseline in Table 3 of
this preamble. Note the cost of controlling methane is significantly
lower than for NMOC because methane constitutes approximately 50
percent of landfill gas, while NMOC represents less than 1 percent of
landfill gas. The incremental dollar-per-Mg cost for NMOC reductions is
$6,000 per Mg NMOC under all of the other options. For option 2.0/40,
however, there are additional reporting requirements for one landfill
affected by this option that would result in a marginally higher actual
cost compared with the option 2.5/40. Therefore, we are not proposing
option 2.0/40. Other than the added reporting costs, the emission
reductions and control costs are identical for options 2.5/40 and 3.0/
40. For the reasons stated in section V.D of this preamble (potential
to miss reductions at landfills that exceed the NMOC emission
thresholds but do not

meet the design capacity thresholds and application of GCCS at
landfills with design capacities between 2.5 and 3.0 million Mg is well
demonstrated), alternative option 3.0/40 is also not being proposed.
    Proposed option 2.5/40. Based on the emission reduction and cost
discussions above and consistent with the President's Methane Strategy
as discussed in section III of this preamble, the EPA is proposing to
reduce the NMOC threshold to 40 Mg/yr. Lowering the NMOC threshold
would result in earlier GCCS installations and additional NMOC and
methane reductions compared to the baseline, as shown in Table 3 of
this preamble. This lowered threshold achieves reductions without
adjusting the initial and expansion lag times and incurring the
associated costs and implementation concerns.
    Reducing the NMOC threshold from the baseline-level of 50 Mg/yr to
40 Mg/yr would affect only three more landfills in 2023 but would
achieve an estimated 13 percent additional reduction in emissions of
NMOC and methane compared to the baseline. Further, this proposal would
maintain the same control device removal criteria as the baseline
except that the controls would have to stay on until three successive
tests for NMOC emissions were below the NMOC emission threshold of 40
Mg/yr instead of 50 Mg/yr. Depending on the waste-in-place of the
landfill at closure and other site-specific factors (e.g., waste
composition, climate), it may take more than 30 years after closure for
a large modern landfill to emit less than the NMOC emission threshold,
and in turn qualify for capping or removing the GCCS. Although the
emission reductions associated with these later years in the landfills'
lifetimes are not incorporated in the environmental and economic
impacts of the baseline and options under consideration, the lower
threshold associated with this proposal would require controls to be
installed for a slightly longer period than the baseline.
    Although some commenters have expressed concerns about the quantity
of emissions after landfills have closed and the GCCS has ceased to
operate, the analysis the EPA conducted demonstrates that GCCS would be
installed for a significant period after landfill closure that is
commensurate with the size and corresponding emissions profile of each
affected landfill. For these reasons, the EPA is proposing that
emissions must be below an emissions threshold of 40 Mg/yr as one of
the three criteria for determining when a GCCS may be capped or
removed. The EPA is also requesting comment on whether these three
criteria are appropriate, and if alternative criteria such as
consecutive quarterly measurements below a surface emission threshold
should also be considered. RCRA, specifically subpart F of Part 258,
also requires supplemental basic post-closure care to maintain cover
integrity.
    Reducing the NMOC threshold also recognizes the opportunity to
build upon progress to date and achieve even more reductions of
landfill gas and its components, consistent with the President's
Methane Strategy as discussed in section III of this preamble. Landfill
gas generated from established waste (waste that has been in place for
at least a year) is typically composed of roughly 50 percent methane
and 50 percent carbon dioxide by volume, with less than 1 percent NMOC.
Because the components of landfill gas are associated with substantial
health, welfare, and climate effects, additional reductions of landfill
gas would improve air quality and reduce health and welfare effects
associated with exposure to landfill gas emissions. Note that in 2012,
landfills continued to be the third largest source of human-related
methane emissions in the United States, representing 18.1 percent of
total methane emissions.\24\ Methane emissions represent 8.7 percent of
all GHG emissions (in CO2e) in the United States.
    Alternative option 2.0/34. Consistent with the President's Methane
Strategy and the potential to achieve a near-term beneficial impact in
mitigating global climate change (see section III of this preamble),
the EPA considered even more stringent alternatives in its analysis of
control options that may achieve additional reductions of methane and
NMOC. For example, reducing the NMOC threshold below 40 Mg/yr in
conjunction with reducing the design capacity to below 2.5 million Mg
or 2.5 million cubic meters, an alternative option 2.0/34 would require
controls at 11 landfills by 2023, which is the same number of landfills
required to control under this proposal. However, under this more
stringent option, four of the 11 landfills would install controls one
year earlier. The extent of the emission reductions for this option
depends on the time period considered. For example, in year 2023,
emission reductions would not be any greater than the proposal.
However, when averaged over the 10-year period (2014-2023), this more
stringent option would achieve additional NMOC and methane reductions
compared with the proposal. Refer to the Environmental Impacts
Analysis,\25\ and the docketed memoranda ``Cost and Emissions Impacts
Resulting from the Landfills NSPS Review. 2014'' for details on the
estimated reductions. Additional emission reductions would be expected
to be achieved over the lifetime of the landfills subject to subpart
XXX because the lower NMOC threshold would require earlier installation
of controls and also require the controls to remain installed for a
longer period. The annualized cost to implement alternative option 2.0/
34 would be higher than the proposal. The EPA did not analyze an option
that reduced the NMOC threshold below 40 Mg/year without also reducing
the design capacity threshold. In light of these additional reductions,
as well as the additional costs to affected entities, the EPA is
soliciting comment on whether an NMOC threshold below 40 Mg/yr in
conjunction with a reduced design capacity threshold should be
considered for new landfills subject to subpart XXX.
---------------------------------------------------------------------------

    \25\ Municipal Solid Waste Landfills, Economic Impact Analysis
for the Proposed New Subpart to the New Source Performance
Standards.
---------------------------------------------------------------------------

VII. Summary of Clarifications and Resolutions That Are the Result of
Implementation Activity

    The EPA proposed amendments to the landfills NSPS (40 CFR part 60,
subpart WWW) on May 23, 2002 (67 FR 36475) to address implementation
issues. Consideration of public comments received and additional
implementation activity led to the proposal of further clarifications
on implementing the landfills regulations on September 8, 2006. After
considering public comments received on the September 8, 2006
amendments and additional implementation activity, we are proposing
resolutions and clarifications of the issues specifically identified
below under new subpart XXX. The EPA plans to address amendments and
clarifications resulting from implementation activities as they apply
to subparts Cc and WWW in a separate document. The EPA will also
address any potential changes to subparts Cc and WWW in a separate
document. Thus EPA is not taking final action on either the May 23,
2002 or the September 8, 2006 proposed rules at this time. In addition
to the specifically identified resolutions and clarifications
associated with the May 23, 2002 and September 8, 2006 proposed rules,
we are proposing a number of provisions in subpart XXX that are
intended to address other implementation issues

that have arisen in the context of subpart WWW.
    2002 Proposed amendments. On May 23, 2002 (67 FR 36475), the EPA
proposed several amendments to subpart WWW, including clarifying what
constitutes treated landfill gas by adding a definition of treatment
system that specified that the system must filter, de-water, and
compress landfill gas.
    2006 Proposed amendments. Public comments on the May 23, 2002
amendments created new questions and caused the EPA to reconsider the
approach we had taken on several proposed amendments, including our
approach to clarifying what constitutes treated landfill gas.
Specifically, we proposed refined definitions of ``treated landfill
gas'' and ``treatment system'' by adding specific numerical values for
filtration and de-watering to provide long-term protection of the
combustion equipment, which would also support good combustion. The
September 8, 2006 amendments also proposed to clarify the monitoring
requirements for treatment systems.
    The following resolutions and clarifications apply to proposed
subpart XXX.

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

    Subpart XXX contains requirements for landfill gas treatment that
are consistent with the September 8, 2006 proposed amendments, except
that the treatment definition would require the water dew point of
landfill gas to be reduced to at least 45 [deg]F, rather than lowered
by at least 20 [deg]F. We also propose to specify a location for the
temperature monitoring device that would demonstrate continuous
compliance with the 45 [deg]F requirement. The measurement device would
be located at (or immediately after) the coalescing filter or other
direct contact moisture removal device that follows the chiller and
removes the condensed moisture. If a landfill owner/operator uses de-
watering equipment that is not based on cooling the gas, such as a
desiccant system, the landfill owner/operator would monitor dew point
instead of temperature. For particulate matter filtration, we propose
to retain the requirement for a filter system to have an absolute
rating no greater than 10 microns.
    We also propose to clarify monitoring, recordkeeping, and reporting
requirements for treatment systems. To ensure that treatment systems
are operating properly to achieve the filtration and de-watering levels
specified in the revised proposed treatment system definition, owners/
operators would install equipment to continuously monitor pressure drop
across a filter, temperature for a chiller-based de-watering system,
and dew point for a non-chiller-based de-watering system. Owners/
operators would record 24-hour block averages. Owners/operators may use
other site-specific monitoring parameters if they demonstrate that such
parameters would effectively monitor filtration or de-watering system
performance. For other site-specific monitoring parameters, owners/
operators must develop operating ranges for each monitored operating
parameter based on manufacturer's recommendations or engineering
analysis and submit those ranges, along with justification, for
approval by the Administrator in an amended design plan. The proposed
recordkeeping and reporting requirements for treatment systems are
similar to those for control device temperature monitoring requirements
already in the NSPS.
    The EPA is considering and taking public comment on an alternative
approach to defining landfill gas treatment and the corresponding
monitoring requirements, as discussed in section IX.A of this preamble.
    Uses of treated landfill gas. Subpart WWW allows landfill owners or
operators the option of achieving compliance by routing the collected
gas to a treatment system ``that processes the collected gas for