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6560-50

EO12866_Landfills_ANPRM 2060AS23 ANPRM_20140616

ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 60

[EPA-HQ-OAR-2014-0451; FRL- ]

RIN 2060-AS23

Emission Guidelines and Compliance Times for Municipal Solid 

Waste Landfills

AGENCY: Environmental Protection Agency.

ACTION: Advanced Notice of Proposed Rulemaking.

SUMMARY: The purpose of this Advanced Notice of Proposed 

Rulemaking (ANPRM) is to request public input on methods to 

reduce emissions from existing municipal solid waste (MSW) 

landfills. The Environmental Protection Agency (EPA) intends to 

consider the information received in response to the ANPRM in 

evaluating whether additional changes beyond those in the 

proposed revisions for new sources are warranted. MSW landfill 

emissions are commonly referred to as “landfill gas” or “LFG”

and contain methane, carbon dioxide (CO2), and nonmethane 

organic compounds (NMOC). Some existing landfills are currently 

subject to control requirements in either the landfill new 

source performance standards (NSPS) or the federal or state 

plans implementing the landfill emission guidelines; both the 

NSPS and emission guidelines were promulgated in 1996. The EPA 
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believes that these guidelines merit review to determine the

potential for additional reductions in emissions of LFG. Such 

reductions would reduce air pollution and the resulting harm to 

public health and welfare. Significant changes have occurred in 

the landfill industry over time, including changes to the size 

and number of existing landfills, industry practices, and gas 

control methods and technologies. The ANPRM recognizes changes 

toin the population of landfills and presents preliminary 

analysis regarding methods for reducing emissions of LFG. In 

determining whether changes to the emission guidelines are 

appropriate, the EPA will, in addition to evaluating the 

effectiveness of various methods for reducing emissions of LFG, 

consider the total methane emission reductions that can be 

achieved in addition to the reductions of NMOC emissions. The 

EPA is also seeking input on whether it should regulate methane 

directly. The ANPRM also addresses other regulatory issues 

including the definition of LFG treatment systems and 

requirements for closed areas of landfills, among other topics. 

DATES: Comments. Comments must be received on or before 

[INSERT THE DATE 60 DAYS AFTER THE DATE OF PUBLICATION IN THE 

FEDERAL REGISTER].

ADDRESSES: Submit your comments, identified by Docket ID 

Number EPA-HQ-OAR-2014-0451, by one of the following methods:
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• Federal eRulemaking Portal: http://www.regulations.gov. 

Follow the online instructions for submitting comments.

• Email: A-and-R-Docket@epa.gov. Include Docket ID No. EPA–

HQ–OAR–2014-0451 in the subject line of your message.

• Fax: (202) 566–9744. Attention Docket ID No. EPA–HQ–OAR–

2014-0451.

• Mail: Environmental Protection Agency, EPA Docket Center 

(EPA/DC), Mailcode 28221T, Attention Docket ID No. EPA–HQ–

OAR–2014-0451, 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–2014-0451. 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. 

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Roberto Morales, OAQPS Document Control Officer (Room C404-02), 

U.S. EPA, Research Triangle Park, NC 27711, Attention Docket ID 

No. EPA-HQ-OAR-2014-0451. The http://www.regulations.gov website 

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 
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available only in hard copy. Publicly available docket materials 

are available either electronically inat

http://www.regulations.gov or in hard copy at the Air Docket, 

EPA/DC, WJC 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 

ANPRM, contact Ms. Hillary Ward, Fuels and Incineration Group, 

Sector Policies and Programs Division, Office of Air Quality 

Planning and Standards (OAQPS)(E143-05), Environmental 

Protection Agency, Research Triangle Park, NC 27711; telephone 

number: (919) 541-3154; fax number: (919) 541-0246; email 

address: ward.hillary@epa.gov.

SUPPLEMENTARY INFORMATION:

Acronyms and Abbreviations. The following acronyms and 

abbreviations are used in this document.

ACT Alternative compliance timeline

ANPRM Advanced Notice of Proposed Rulemaking

AR4 IPCC Fourth Assessment Report

ARB Air Resources Board

BMP Best management practice

CAA Clean Air Act

CBI Confidential business information

CFR Code of Federal Regulations
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CO2 Carbon dioxide

CO2e Carbon dioxide equivalent

CRDS Cavity ringdown spectroscopy

DOC Degradable organic carbon

EPA Environmental Protection Agency

FTIR Fourier Transform Infrared

GCCS Gas collection and control system

GHG Greenhouse gas

GHGRP Greenhouse Gas Reporting Program

GWP Global warming potential

HAP Hazardous air pollutants

HOV Higher operating value

IPCC Intergovernmental Panel on Climate Change

IRIS Integrated Risk Information System

LFG Landfill gas

LMOP Landfill Methane Outreach Program

m3 Cubic meters

Mg Megagram

Mg/yr Megagram per year

MSW Municipal solid waste

NAAQS National ambient air quality standards

NAICS North American Industry Classification System

NMOC Nonmethane organic compounds

NOx Nitrogen oxides

NSPS New source performance standards

NTTAA National Technology Transfer and Advancement Act

OAQPS Office of Air Quality Planning and Standards

OMB Office of Management and Budget

PM2.5 Fine particulate matter

ppm Parts per million

ppmv Parts per million by volume

PRA Paperwork Reduction Act

RCRA Resource Conservation and Recovery Act

RFA Regulatory Flexibility Act

RPM Radial plume mapping 

SEM Surface emissions monitoring

SIP State implementation plan
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Tg Teragram

TDL Tunable diode laser

Tg Teragram

TTN Technology Transfer Network

UMRA Unfunded Mandates Reform Act

VOC Volatile organic compounds

Organization of This Document. The following outline is 

provided to aid in locating information in this notice.

I. General Information

A. Does this action apply to me?

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

C. Where can I get a copy of this document and other related 

information?

II. Background

A. Landfill Gas Emissions and Climate Change

B. What is the EPA’s authority for reviewing the emission 

guidelines?

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

D. Why are we reviewing the emission guidelines?

E. What is the statutory authority for landfill emission 

guidelines?

F. What are the landfill emission guidelines and what sources 

would be affected by a review of the emission guidelines?

G. How would changes in applicability affect sources currently 

subject to subpart WWW?

III. Why is the EPA concerned about air quality effects from MSW 

landfills?

A. Background on the MSW Landfill Sector

B. What emissions are associated with existing MSW landfills?

C. What emission reductions are currently being achieved from 

MSW landfills?

D. What are the health and welfare effects of LFG emissions?

IV. Topics for Which the EPA is Seeking Input

A. Taking Reductions in Methane Emissions Into Account in 

Reviewing the Emission Guidelines
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B. Potential Changes to Regulatory Framework for Existing 

Sources

C. Emission Reduction Techniques and GCCS Best Management 

Practices

D. Alternative Monitoring, Reporting, and Other Requirements

E. Alternative Emission Threshold Determination Techniques

F. Considerations for Implementation at Closed vs. Active 

Landfills

G. Implementation Issues

V. Statutory and Executive Order Reviews

I. General Information

A. Does this action apply to me?

This ANPRM addresses existing MSW landfills and associated 

solid waste management programs. Potentially affected categories 

and entities include those listed in Table 1 of this notice.

Table 1. Regulated Entities

Category NAICSa Examples of affected facilities

Industry: Air 

and water 

resource and 

solid waste 

management

924110 Solid waste landfills

Industry: 

Refuse systems-

-solid waste 

landfills

562212 Solid waste landfills

State, local 

and tribal 

government 

agencies

924110 Administration of air and water 

resource and solid waste management

programs

a North American Industry Classification System.

This table is not intended to be exhaustive but rather 

provides a guide for readers regarding entities likely to be 

Formatted: TOC 1,TOC 1-GHG Preamble,TOC

1-GHG Rule, Tab stops: 6.49", Right,Leader: ...
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regulated. The EPA is specifically requesting input on MSW 

landfills subject to state plans or federal plan (40 CFR part 

62, subpart GGG) that implement the emission guidelines at 40 

CFR part 60, subpart Cc. The EPA will also take this information 

into account in determining if additional changes to the NSPS at 

40 CFR part 60, subpart WWW are appropriate. If you have any 

questions regarding whether the EPA is seeking input regarding a 

particular MSW landfill, 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.
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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-2014-0451. 

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.

Make sure to submit your comments by the comment period 

deadline identified in the preceding section titled DATES.

2. Docket

The docket number for the review of the municipal solid 

waste landfills emission guidelines is Docket ID No. EPA-HQ-OAR2014-0451. Docket ID Nos. EPA-HQ-OAR-2003-0215 and A-88-09 

contain supporting information for 40 CFR part 60, subparts Cc

and WWW.

C. Where can I get a copy of this document and other related 

information? 

WorldwideWorld Wide Web (WWW). In addition to being 

available in the docket, an electronic copy of this ANPRM is 

available on the Technology Transfer Network (TTN) website. 

Following signature, the EPA will post a copy of this notice on 
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the TTN’s policy and guidance page for newly proposed or 

promulgated rules at 

http://www.epa.gov/ttn/oarpgatw/landfill/landflpg.html. The TTN 

provides information and technology exchange in various areas of 

air pollution control.

II. Background

A. Landfill Gas Emissions and Climate Change 

In June 2013, President Obama issued a Climate Action Plan 

directing the EPA and five other federal agencies to take a wide 

variety of significant steps to reduce methane emissions. The 

plan, which encompassed a wide range of actions and voluntary

initiatives, 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.”

The focus on reducing methane emissions reflects the fact 

that methane is a potent GHG with a global warming potential 
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(GWP) that is 25 times greater than that of CO2.1

In response to the directive in the 2013 Climate Action 

Plan, the “Climate Action Plan: Strategy to Reduce Methane 

Emissions” (the Methane Strategy) was released in March 2014. 

The Methane Strategy noted that the landfill standards at issue 

here and voluntary programs already in place have considerably 

reduced methane emissions, while creating jobs and improving 

public health. 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; to issue an ANPRM to 

explore options to address emissions from existing landfills;

and to encourage energy recovery from LFG through voluntary 

programs.

Methane has an 

atmospheric life of 12 years, and because of its potency as a 

GHG and its atmospheric life, reducing methane emissions is one 

of the best ways to achieve a near-term beneficial impact in 

mitigating global climate change.

The EPA has long recognized the climate benefits associated 

with reducing methane emissions from landfills. In the 1991 

 

1 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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Landfill NSPS Background Information Document,2

“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 the rate and magnitude of these 

changes are uncertain.”

the EPA noted 

that reduction of methane emissions from MSW landfills is one of 

the many options available to reduce global warming. When the 

EPA promulgated the NSPS for MSW landfills, which regulates MSW 

landfill emissions (landfill gas), in 1996, the EPA noted the 

climate co-benefit of controlling methane, which was not as well 

understood at the time as today (61 FR 9917, March 12, 1996). In 

1996, the EPA stated:

Since 1996, the EPA and the scientific community have 

gained a better understanding of GHGs, including methane, and 

their effects on climate change and human health and welfare. In 

2009, the EPA Administrator issued the document known as the 

 

2 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) 
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Endangerment Finding under CAA section 202(a)(1).3 In the 

Endangerment Finding, which focused on public health and public 

welfare impacts within the United States, the Administrator 

found that elevated concentrations of GHGs4

The EPA is reviewing the MSW landfills emission guidelines 

and in light of the President’s Climate Action Plan, the Methane 

Strategy, and improvements in the science related to GHG 

emissions, is exploring opportunities to achieve additional 

reductions in emissions, including methane emissions. The EPA 

intends to proposeissue a proposed review of the emission 

guidelines by March 2015 and take final action on the proposal 

by March 2016.

in the atmosphere may 

reasonably be anticipated to endanger the public health and 

welfare of current and future generations. In light of this 

finding, the EPA has been examining regulatory options for 

reducing GHG emissions.

Landfill gas is a collection of air pollutants, including 

methane and NMOC. Landfill gas is typically composed of roughly 

50-percent methane, 50-percent CO2, and less than 1 percent NMOC

by volume. The NMOC portion of LFG, although a small amount by 

 page 2-15. 3 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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volume, can contain a variety of significant air pollutants. 

NMOC includes various organic hazardous air pollutants (HAP) and 

volatile organic compounds (VOC). When 40 CFR part 60, subparts 

Cc and WWW were promulgated in 1996, NMOC was selected as a 

surrogate for MSW landfill emissions because NMOC contains the 

landfill air pollutants that pose more concern due to their 

adverse health and welfare effects. Today, there is a greater 

emphasis on methane emissions because of their effects on 

climate change, resulting in risk to human health and welfare..

Note that in 2012, landfills represented 18.1 percent of total 

U.S. methane emissions.5 Methane represents 8.7 percent of all 

GHG emissions (in CO2e) in the United States.6

B. What is the EPA’s authority for reviewing the emission 

guidelines? 

For these reasons, 

the EPA is considering changes to the emission guidelines that

are based on reducing the methane and NMOC components of LFG. 

The EPA is seeking input on whether it should regulate methane 

directly. 

 4 Carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), hydrofluorocarbons 

(HFCs), perfluorocarbons (PFCs), and sulfur hexafluoride (SF6). 5 Total U.S. methane emissions were just below 600 million Mg CO2e in 2012.

“Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2012.” Available at

http://www.epa.gov/climatechange/ghgemissions/gases/ch4.html

6 U.S. EPA. 2012. “Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-

2012. Executive Summary.” Available at

http://www.epa.gov/climatechange/Downloads/ghgemissions/US-GHG-Inventory-2014-

Chapter-Executive-Summary.pdf.
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The EPA is not statutorily obligated to conduct a review of 

the emission guidelines, but has the discretionary authority to 

do so when circumstances indicate that this is appropriate. 

Based on changes in the landfills industry and changes to the 

populationin size, ownership, and age of landfills since the 

emission guidelines were promulgated in 1996, the EPA has 

concluded that it is appropriate to review the landfills 

emission guidelines at this time. As part of the data collection 

efforts for the statutorily mandated review of the MSW landfills 

NSPS, the EPA received, and has since compiled, new information 

on existing landfills. That information, together with the 

information being solicited through this ANPRM, will allow the 

EPA to conduct an assessment of the current population of

existing landfills, their practices, emissions and the potential 

for reductions in emissions. Any changes to the emission 

guidelines that might result from this review will ultimately

apply to landfills that accepted waste on or after November 8, 

19877

 

7 This date in 1987 is the date on which permit programs were established 

under the Hazardous and Solid Waste Amendments of RCRA. This date was also 

selected as the regulatory cutoff in the EG for landfills no longer receiving 

wastes because EPA judged States would be able to identify active facilities 

as of this date.

, and that commenced construction, reconstruction, or 

modification prior to publication of proposed revisions to the 
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landfills NSPS, 40 CFR part 60, subpart XXX, as discussed in 

further detail in sections II.F and II.G of this notice.

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

The purpose of this ANPRM is to request public input on 

methods to reduce emissions from existing MSW landfills and to 

request input on potential resolutions or clarifications 

regarding issues that have arisen during implementation of the 

existing standards. 

D. Why are we reviewing the emission guidelines?

The EPA is considering changes to the emission guidelines 

for a number of reasons, including the following: (1) The 

opportunity to build on progress to date and achieve additional 

reductions of LFG and its components, consistent with the 

President’s Methane Strategy, (2) changes to thein size, 

ownership, and age of landfills population as reflected in new 

data, (3) new options for demonstrating compliance, and (4) the 

completion of efforts regarding implementation issues for which 

the EPA previously proposed resolution. The EPA is considering 

these topics in its review, as discussed in the following 

sections.

1. Opportunity to Achieve Additional Reductions from Existing 

Landfills
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The EPA recognizes the opportunity to build on progress to 

date and achieve additional reductions of LFG and its 

components. A subset of existing landfills are controlled by 

either the landfill emission guidelines (40 CFR part 60, subpart 

Cc) or by the landfill NSPS (40 CFR part 60, subpart WWW). 

Controls installed as a result of these regulations have 

successfully reduced LFG emissions. Although methane emissions 

from landfills in 2012 are 30 percent lower than they were in 

1990, methane emissions from landfills continue to be a concern. 

Despite these controls installed to date, in 2012, landfills 

emitted 102.8 teragrams (Tg) (or 102.8 million metric tons)

CO2e, making landfills the third largest source of human-related 

methane emissions in the United States. The number of existing 

landfills (>1,800) is significantly higher than the number of 

new landfills (21) that are projected to open in the next 5 

years. Therefore, anyif there are cost effective changes to 

thefor existing landfills, revising these regulations may 

realize their greatesta great benefit when applied togiven the 

number of existing landfills.

In this ANPRM, the EPA is exploring and requesting input on 

approaches that have the potential to achieve additional 

emission reductions from MSW landfills. Some of these approaches 

are adjustments to the current framework of the landfills 
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regulations, others would complement the existing framework, and 

still others would be entirely outside the current framework. 

These approaches are presented in section IV of this notice and 

include potential adjustments to the design capacity threshold;

the NMOC emissions threshold; and the timing of installing,

expanding and removing the gas collection and control system

(GCCS). Approaches also include potential changes to emission 

threshold determinations, consideration of best management 

practices (BMPs), and new technologies that could improve 

collection and control of LFG emissions. The EPA will consider 

the input and data received on these approaches during the 

review of the landfills emission guidelines and determine 

whether it is appropriate to revise the emission guidelines to 

further reduce LFG emissions from existing landfills.

2. New Data Available Since Emission Guidelines were Originally 

Promulgated in 1996

The EPA collected current data for the statutorily required 

review of the landfills NSPS, 40 CFR part 60, subpart WWW. Three 

sources were used for that effort: A landfill and LFG energy 

project database maintained by EPA’s Landfill Methane Outreach 

Program (LMOP), a voluntary survey of landfills, and the 

Greenhouse Gas Reporting Program (GHGRP). The creation of the 

landfill dataset, including identification of the sources of the 
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information contained therein, 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 the dataset, which included landfill-specific data such 

as landfill open and closure year, landfill design capacity, 

landfill design area and landfill depth, to examine the effects 

of potential changes to the size and emission thresholds for 

installing controls. The dataset also provides information on 

landfill practices such as liquids recirculation, waste 

composition, presence and type of GCCS and energy recovery 

projects. The availability of new data on MSW landfills is 

discussed in section III.AII.D.2 of this notice.

3. New Options for Demonstrating Compliance

The EPA is considering and requesting input on potential 

options for demonstrating compliance. For example, the EPA is 

considering alternative wellhead monitoring requirements that 

could include exclusion or reduced frequency of temperature, 

oxygen/nitrogen monitoring requirements and whether such 

adjustments should be limited only to landfills that 

beneficially use LFG or should be available to all landfills, 

including small entities. The EPA is considering and requesting 

public input on potential approaches to surface emission 

monitoring. Approaches include changing the walking pattern that 
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traverses the landfill, adding an integrated methane 

concentration measurement and allowing sampling only when wind 

is below a certain speed. These new options for demonstrating 

compliance are discussed in section IV.D of this notice. The EPA 

will consider the input and data received on these approaches 

during the review of the landfills emission guidelines with the 

intent of further reducing LFG emissions from existing 

landfills.

4. Concerns Arising from Implementation of Subparts Cc and WWW 

that the EPA Plans to Address in a Forthcoming Proposal

The landfill emission guidelines were originally 

promulgated in 1996. Over time, the EPA has become aware of a 

number of implementation issues associated with the regulatory 

requirements and for which landfill owners and operators, as 

well as regulators, need clarification. The EPA proposed 

amendments to the landfills NSPS and emission guidelines (40 CFR 

part 60, subpart WWW and 40 CFR part 60, subpart Cc) on May 23, 

2002 (67 FR 36475), and September 8, 2006 (71 FR 53271). Those 

amendments were never finalized. The EPA is not taking final 

action on either the May 23, 2002, or the September 8, 2006,

proposed rules through this ANPRM, but we are soliciting input

on the unresolved implementation issues. These issues include 

but are not limited to: LFG treatment, accounting for emissions 
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from closed areas of landfills, surface monitoring, and 

corrective action timelines. Note that the EPA addressed some of 

these implementation issues as they apply to new MSW landfills 

in the Federal Register notice that proposes a new subpart 

resulting from the EPA’s review of the landfills NSPS. The EPA 

plans to address amendments and clarifications resulting from 

implementation activities as they apply to subparts Cc and WWW 

in forthcoming amendments to these subparts. See section IV.G of 

this notice for details. 

E. What is the statutory authority for landfill emission

guidelines?

Clean Air Act (CAA) section 111, which Congress enacted as 

part of the 1970 CAA Amendments, establishes mechanisms for 

controlling emissions of air pollutants from stationary sources. 

This provision requires the EPA to promulgate a list of 

categories of stationary sources that the Administrator, in his 

or her judgment, finds “causes, or contributes significantly to, 

air pollution which may reasonably be anticipated to endanger 

public health or welfare.”8 The EPA has listed more than 60 

stationary source categories under this provision, including 

municipal solid waste landfills.9

 

8 CAA section 111(b)(1)(A).

Once EPA lists a source 

9 See 40 CFR part 60, subparts Cb through OOOO.
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category, the EPA must, under CAA section 111(b)(1)(B), 

establish “standards of performance” for emissions of air 

pollutants from new sources in the source categories.10

When the EPA establishes NSPS for new sources in a 

particular source category, the EPA is also required, under CAA 

section 111(d)(1), to prescribe regulations for states to submit 

plans regulating existing sources in that source category for 

any air pollutant that, in general, is not regulated under the 

CAA section 109 requirements for the National Ambient Air 

Quality Standards (NAAQS) or regulated under the CAA section 112 

requirements for HAP. CAA section 111(d)’s mechanism for 

regulating existing sources differs from the one that CAA 

section 111(b) provides for new sources because CAA section 

111(d) contemplates states submittingis implemented through 

state plans that establish “standards of performance” for the 

affected sources and that contain other measures to implement 

and enforce those standards. 

These 

standards are known as new source performance standards or NSPS, 

and they are national requirements that apply directly to the 

sources subject to them. 

“Standards of performance” are defined under CAA section 

111(a)(1) as standards for emissions that reflect the emission 

 

10 CAA section 111(b)(1)(B), 111(a)(1).
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limitation achievable from the “best system of emission 

reduction,” considering costs and other factors, that “the 

Administrator determines has been adequately demonstrated.” CAA 

section 111(d)(1) grants states the authority, in applying a 

standard of performance to particular sources, to take into 

account the source’s remaining useful life or other factors. 

Under CAA section 111(d), a state must submit its plan to 

the EPA for approval, and the EPA must approve the state plan if 

it is “satisfactory.” 11 If a state does not submit a plan, or if 

the EPA does not approve a state’s plan, then the EPA must 

establish a plan for that state.12

The EPA issued regulations implementing CAA section 111(d) 

in 1975.

Once a state receives the 

EPA’s approval for its plan, the provisions in the plan become 

federally enforceable against the entity responsible for 

noncompliance, in the same manner as the provisions of an 

approved State Implementation Plan (SIP) under CAA section 110. 

13

 

11 CAA section 111(d)(2)(A).

These implementing regulations provide that, in 

promulgating requirements for sources under CAA section 111(d), 

the EPA first develops regulations known as “emission 

guidelines,” which establish binding requirements that states 

12 CAA section 111(d)(2)(A). 13 “State Plans for the Control of Certain Pollutants From Existing Facilities,” 

40 FR 53,340 (November 17, 1975).
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must address when they develop their plans.14 The implementing 

regulations also establish timetables for state and EPA action: 

states must submit state plans within 9 months of the EPA’s 

issuance of the guidelines,15 and the EPA must take final action 

on the state plans within 4 months of the due date for those 

plans,16 although the EPA has authority to extend those 

deadlines.17

Over the last 40 years, under CAA section 111(d), the 

agency has regulated four pollutants from five source categories 

(i.e., sulfuric acid plants (acid mist), phosphate fertilizer 

plants (fluorides), primary aluminum plants (fluorides), Kraft 

pulp plants (total reduced sulfur), and municipal solid waste 

landfills (LFG)).18

F. What are the landfill emission guidelines and what sources 

would be affected by a review of the emission guidelines?

 

14 40 CFR 60.22. In the 1975 rulemaking, the EPA explained that it used the term 

“emissions guidelines” – instead of emissions limitations – to make clear that 

guidelines would not be binding requirements applicable to the sources, but 

instead are “criteria for judging the adequacy of State plans.” 40 FR 53343. 15 40 CFR 60.23(a)(1). 16 40 CFR 60.27(b). 17 See 40 CFR 60.27(a). 18 See “Phosphate Fertilizer Plants; Final Guideline Document Availability,” 42 FR 

12022 (March 1, 1977); “Standards of Performance for New Stationary Sources; 

Emission Guideline for Sulfuric Acid Mist,” 42 FR 55796 (October 18, 1977); “Kraft 

Pulp Mills, Notice of Availability of Final Guideline Document,” 44 FR 29828 (May 

22, 1979); “Primary Aluminum Plants; Availability of Final Guideline Document,” 45 

FR 26294 (April 17, 1980); “Standards of Performance for New Stationary Sources 

and Guidelines for Control of Existing Sources: Municipal Solid Waste Landfills, 

Final Rule,” 61 FR 9905 (March 12, 1996). 
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The Emission Guidelines and Compliance Times for Municipal 

Solid Waste Landfills (emission guidelines) are codified at 40 

CFR part 60, subpart Cc. The emission guidelines cross reference 

many provisions in the Standards of Performance for Municipal 

Solid Waste Landfills (landfills NSPS)(40 CFR part 60, subpart 

WWW), including control requirements, operational standards, 

monitoring provisions, and reporting and recordkeeping

requirements. As a result, many of the proposed changes to the 

standards of performance for new, reconstructed, and modified 

MSW landfills could affect subpart Cc. A detailed summary of the 

current emission guideline requirements appears in section 

IV.B.1 of this notice.

CAA section 111(d) calls for a partnership between the EPA 

and states, as described above. To recap, the EPA establishes

source-category-specific emission guidelines that specify the 

minimum requirements for an approvable state plan, including the 

requisite level of emission reductions that must be achieved. 

Each state must develop a state plan establishing standards of 

performance for the affected sources in the state based on the 

requirements of the emission guidelines. The state must submit 

its state plan to the EPA for approval. The EPA reviews the 

state plan to ensure that it meets at least the minimum 

requirements of the emission guidelines, and approves the plan 
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if it does. If the state does not submit a state plan, or the 

state plan is disapproved, the EPA would have the authority to 

promulgate a federal plan under CAA section 111(d)(2)(A). MSW 

landfills constructed, modified or reconstructed prior to 

proposal of the revised landfills NSPS, 40 CFR part 60, subpart 

XXX that have accepted waste since November 8, 1987 would be 

considered “existing” and would be affected by any changes to 

the emission guidelines resulting from this review. States with 

designated facilities would be required to develop (or revise) 

and submit a state plan to the EPA within 9 months of 

promulgation of any revisions to the emission guidelines unless 

the EPA specifies a longer time frame. Any revisions to an 

existing state plan and any newly adopted state plan must be 

established following the requirements of 40 CFR part 60, 

subpart B. Those requirements include making the state plan 

publically available and providing opportunity for public 

discussion. Once the EPA receives a complete state plan or plan 

revision and completes its review of that plan or plan revision, 

the EPA will propose the plan or plan revision for approval or 

disapproval and must take final action to approve or disapprove 

the plan or plan revision no later than 4 months after the date 

the plan or plan revision was required to be submitted. The EPA 

will publish state plan approvals or disapprovals in the Federal 
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Register and will include an explanation of its decision. The 

EPA will also revise the existing federal plan (40 CFR part 62, 

subpart GGG) to incorporate any changes and other requirements 

that the EPA promulgates as a result of its review of the 

emission guidelines. The revised federal plan will apply in 

states which have not received approval of any necessary revised 

state plan until such time as the revised state plan is 

approved.

G. How would changes in applicability affect sources currently 

subject to subpart WWW? 

If the EPA were to revise the landfills emission guidelines

to increase their stringency, then a landfill currently subject 

to 40 CFR part 60, subpart WWW would need to comply with the 

more stringent requirements in the revised state plan or federal 

plan implementing the revised emission guidelines (40 CFR part 

60, subpart Cc) as such sources would be existing sources with 

respect to the revised NSPS.19

 

19 As discussed above, the emission guidelines currently rely on subpart WWW 

for their substantive requirements. As a result, any increase in the 

stringency of the emission guidelines would necessarily make them more 

stringent than the existing requirements in subpart WWW.

States would have to update their 

inventory of existing landfills to include these landfills. Note 

that all MSW landfills that are subject to subpart WWW would 

continue to comply with the requirements found in subpart WWW 
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unless and until they are covered by a more stringent state or 

federal plan implementing the amended emission guidelines.

III. Why is the EPA concerned about air quality effects from MSW 

landfills?

The EPA is concerned about LFG emissions because of the 

public health and welfare effects that result from these 

emissions. 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 CO2 by 

volume, with less than 1 percent NMOC. In promulgating the 

emission guidelines in 1996, the EPA’s concerns regarding the 

adverse effects of emissions of LFG on human health and welfare 

were focused primarily on the NMOC portion of LFG. The NMOC 

portion of LFG can contain a variety of air pollutants, 

including VOCs and various organic HAP, all of which have 

various health effects, as discussed in section III.D of this 

notice. In light of the Methane Strategy, the EPA is considering 

changes to the emission guidelines that are based on reducing 

emissions of the methane and NMOC components of LFG. Once 

emitted into the atmosphere, methane contributes to warming of 

the atmosphere, which over time leads to increased air and ocean 

temperatures, changes in precipitation patterns, and sea level 
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rise, among other impacts, as discussed in section III.D of this 

notice.

A. Background on the MSW Landfill Sector

Section 111 of the CAA requires the EPA Administrator to 

list categories of stationary sources that in the 

Administrator’s judgment cause or contribute significantly to 

air pollution that may reasonably be anticipated to endanger 

public health or welfare (42 U.S.C. 7411(b)(1)(A)). 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 the NSPS, which apply to new (including modified and

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). 

The EPA also defined the MSW landfills source category, 

identified municipal solid waste landfill emissions (commonly 

referred to as LFG) as the pollutant for which standards should 

be developed, and determined the applicability thresholds and 

emission level of the standards. 
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1. Definition

An MSW landfill is defined in the landfills regulations as: 

“An entire disposal facility in a contiguous geographical space 

where household waste is placed in or on land. An MSW landfill 

may also receive other types of Resource Conservation and 

Recovery Act (RCRA) subtitle D wastes such as commercial solid 

waste, nonhazardous sludge, conditionally exempt small quantity 

generator waste, and industrial solid waste. Portions of an MSW 

landfill may be separated by access roads. An MSW landfill may 

be publicly or privately owned. An MSW landfill may be a new MSW 

landfill, an existing MSW landfill or a lateral expansion” (40 

CFR 60.32c and 60.751). 

Household waste is the primary component of MSW, accounting 

for 55 to 65 percent of total MSW generated, followed by the 

commercial and institutional sectors.20

2. Characterization of Existing Landfills

Household waste includes 

solid waste from single- and multiple-family homes, hotels and 

motels, ranger stations, crew quarters, campgrounds, picnic 

grounds and day-use recreation areas. 

Many changes have occurred in the landfill industry since 

the landfill emission guidelines were originally promulgated in 
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1996. Among the changes are changes in landfill characteristics 

and population (i.e., size, ownership, age); proliferation of 

LFG energy projects; the availability of more comprehensive data 

on landfills from mandatory and voluntary EPA programs; and the 

introduction of new techniques for collecting, reducing, and 

monitoring LFG emissions.

Size, Ownership, Age. The number and size distribution of 

MSW landfills in the United States has evolvedchanged over the 

last 25 years, with a trend toward fewer active, but larger,

landfills. Since 1988, the number of active MSW landfills in the 

United States has decreased by approximately 75 percent (from 

approximately 7,900 in 1988 to approximately 1,900 in 2009).21,22

During this time, the overall disposal capacity has remained 

fairly constant, indicating a trend towards fewer, but larger 

landfills23 in more remote locations..24

The data also show a trend away from public ownership. The 

share of sites that are publicly owned has decreased from 83 

 20 U.S. Environmental Protection Agency. 2011. Municipal Solid Waste 

Generation, Recycling, and Disposal in the United States Tables and Figures 

for 2010. EPA-530-F-11-005. Washington, DC: U.S. EPA. 21 U.S. Environmental Protection Agency. 2010. “Municipal Solid Waste in the 

United States: 2009 Facts and Figures.” 22 O’Brien, Jeremy K. 2006. “Contracting out: Adapting local integrated waste 

management to regional private landfill ownership.” Waste Management World.

23 Solid Waste Association of North America (SWANA). 2007. “The Regional 

Privately-Owned Landfill Trend and Its Impact on Integrated Solid Waste 

Management Systems.” February 2007.
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percent in 1984 to 64 percent in 2004.25,26 LargeInstead, large, 

private companies have the ability to accommodate the increased 

costs of owning a landfill, because owningused economy of scale 

for cost expenditures and own multiple sites, many of which have 

large capacities, provides an economy of scale for cost 

expenditures.. To offset the cost of constructing and 

maintaining modern landfills, facility owners construct large 

facilities that attract high volumes of waste from a large 

geographic area. By maintaining a high volume of incoming waste, 

landfill owners have the ability to keep tipping fees relatively 

low, which subsequently attracts more business.27

LFG Energy Projects. The number of LFG energy projects has 

also increased substantially over the last two decades. In 1996, 

there were approximately 160 operational LFG energy projects and 

approximately 700 candidate landfills according to data obtained 

by the EPA LMOP. According to LMOP, as of March 2014, there are 

636 operational LFG energy projects and 450 landfills that 

remain candidates for energy recovery. LMOP is a voluntary 

 24 Solid Waste Association of North America (SWANA). 2007. “The Regional 

Privately-Owned Landfill Trend and Its Impact on Integrated Solid Waste 

Management Systems.” February 2007. 25 U.S. Environmental Protection Agency. 2010. “Municipal Solid Waste in the 

United States: 2009 Facts and Figures.”

26 O’Brien, Jeremy K. 2006. “Contracting out: Adapting local integrated waste 

management to regional private landfill ownership.” Waste Management World. 27 U.S. Environmental Protection Agency. 2002. Solid Waste and Emergency 

Response. “Waste Transfer Stations: A Manual for Decision-Making.”

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assistance program that helps to reduce methane emissions from 

landfills by encouraging recovery and beneficial use of LFG.

Availability of More Comprehensive Data. In 2010, the EPA 

GHGRP began collecting information from existing MSW landfills 

that accepted waste on or after January 1, 1980. Approximately 

1,200 landfills generated and generate methane in amounts 

equivalent to 25,000 metric tons of carbon dioxide equivalent 

(CO2e) or more per year. According to data collected through the 

GHGRP, approximately 1,200 landfills generated methane in 

amounts equivalent to 25,000 metric tons of CO2e or more per 

year, using a GWP of 25. (CO2e is an expression of methane in 

terms of the carbon dioxide equivalents, given the methane GWP 

of 2528.) 25,000 metric tons of CO2e is equal to about 6.5 

megagrams (Mg) NMOC and 1,000 Mg methane per year.29

 

28 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.

(A megagram 

is also known as a metric ton, which is equal to 1.1 U.S. short 

tons or about 2,205 pounds.) Reporting includes data elements 

such as annual modeled methane generation and methane emissions 

from the landfill, as well as annual methane destruction (for 

landfills with GCCSs). Beginning with reporting year 2013, the 
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GHGRP data includes additional data elements for which reporting 

was previously deferred, such as landfill open and closure 

dates, waste acceptance rates, flow of LFG for destruction, 

methane concentration and gas collection efficiency.; this data 

will be used to refine the analyses discussed in “Methodology 

for Estimating Cost and Emission Impacts of MSW Landfill 

Regulations. 2014” and “Summary of Landfill Dataset Used in the 

Cost and Emission Reduction Analysis of Landfill Regulations. 

2014,” both of which are available in the docket. The EPA plans 

to incorporate this new information into the proposal for the 

emission guidelines review. LMOP has collected information on 

landfills since the program’s inception in 1996 and maintains a 

database of over 2,000 existing landfills and LFG energy 

projects. The database includes landfill information provided to 

LMOP and from publically available sources, including the GHGRP 

dataset. In addition, the EPA conducted a voluntary landfill 

survey in 2010 and received information from 167 landfills. 

A dataset of approximately 2,400 landfills resulted from 

the three sources listed above: The GHGRP, the LMOP database and 

voluntary survey of landfills. Of these 2,400 landfills, 

approximately 1,800 hadhave sufficient data to use in the 

 29 Calculated using the AP-42 default factor of 595 ppmv and 50 percent 

methane. U.S. EPA, AP-42, Fifth Edition, Compilation of Air Pollutant Emission 

Factors, Volume 1: Stationary Point and Area Sources. 1995.
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preliminary cost and reduction analysis as the EPA begins its 

review of the emission guidelines. 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.” Based on this dataset, 

several observations can be made.

Location and Size. The 1,800 landfills are located in all 

50 states and two territories and range widely in size from 208 

tons189 Mg to 142129 million tonsMg of waste-in-place as of 

2014. Approximately half of the landfills have a design capacity 

of at least 2.5 million Mg. 

Active vs. Closed. Approximately half of the existing 

landfills are still accepting waste as of 2014. Approximately 40

percent of the landfills stopped accepting waste prior to 2005.

Among landfills that have a design capacity of at least 2.5 

million Mg, only 16 percent of the landfills stopped accepting 

waste prior to 2005.

Leachate Recirculation. Leachate recirculation is used at 

many landfills to manage on-site leachate. Concurrently, this 

operational practice accelerates waste decomposition and gas 

generation rates at the landfills. Under 40 CFR part 98, subpart 

HH of the GHGRP, landfills must report whether or not they 

employ leachate recirculation and if so, the frequency of that 
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recirculation. Based on GHGRP data from the 2012 reporting year, 

over 300 landfills accepting waste after 1987 indicated that 

leachate recirculation was used. Of those, over 200 landfills 

indicated the leachate was recirculated several times per year 

over the past 10 years of operation. 

Other Liquids Addition. Since 2004, 14 states have received 

program approval to issue permits to MSW landfills to add 

liquids other than leachate under the Research Development and 

Demonstration provisions of 40 CFR 258.4. This operational 

practice also accelerates waste decomposition and gas generation 

rates at the landfills. 

Other Trends. The estimated annual quantity of waste placed 

in MSW landfills increased 26 percent from approximately 205 Tg 

in 1990 to 284 Tg in 2012.30 The annual amount of waste generated 

and subsequently disposed in MSW landfills varies annually and 

depends on several factors (e.g., the economy, consumer 

patterns, recycling and composting programs, inclusion in a 

waste collection service and the availability of other 

alternative options for disposal and their price); but the total 

amount of MSW generated is expected to continue to increase as 

the U.S. population continues to grow. The composition of 
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materials disposed of in MSW landfills has also changed 

significantly since 1990. See section IV.C.3 of this notice for 

additional details on waste composition trends.

B. What emissions are associated with existing MSW landfills? 

The EPA estimates that the potential uncontrolled emissions 

from the approximately 1,800 landfills in its regulatory 

analysis dataset (as explained in section II.D.2 of this notice)

are approximately 66,400 Mg NMOC and 10 Tgmillion Mg methane

(258 Tgmillion Mg CO2e) in 2014. 

Looking beyond the modeled dataset, the 2012 Inventory of 

U.S. Greenhouse Gas Emissions and Sinks: 1990-2012, shows a 

growth in uncontrolled emissions from MSW landfills, from 172.6 

Tg CO2e in 1990 to 280.0 Tg CO2e in 2012.31 If controls are 

considered, emissions from landfills have decreased from 147.8 

Tg CO2e in 1990 to 102.8 CO2e in 2012 from both regulatory and 

voluntary programs.32

C. What emission reductions are currently being achieved from 

MSW landfills? 

1. Emission Reductions Due to Subparts Cc and WWW 

 30 U.S. EPA. Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2012. 

April 2014. See Annex 3.14, Table A-261. 

http://www.epa.gov/climatechange/ghgemissions/usinventoryreport.html

31 U.S. EPA. Inventory of U.S. Greenhouse Gas Emissions And Sinks: 1990-2012 

(April 2014) Table 8-3 

http://www.epa.gov/climatechange/ghgemissions/usinventoryreport.html
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To estimate the emission reductions, the EPA applied the 

current design capacity and NMOC emission rate thresholds in the 

MSW landfills regulations, and the time allowed for installing, 

expanding and removing the GCCS to the modeled emission 

estimates discussed in section IV.B of this notice.

Table 2 of this notice summarizes the reductions currently 

being achieved at existing landfills in 2014 as a result of 40 

CFR part 60, subpart WWW and the federal and state plans 

implementing the emission guidelines. This table reflects the 

current baseline level of control at existing landfills: 

Landfills greater than or equal to 2.5 million Mg and 2.5 

million cubic meters (m3) must install a GCCS when NMOC 

emissions reach or exceed 50 megagrams per year (Mg/yr). The 

table includes emission reductions for NMOC and methane.

Table 2. Baseline Emission Reductions in 2014 at Existing 

Landfills

Option

No. of 

landfills 

affected

No. of 

landfills 

controlling

No. of 

landfills 

reporting 

but not 

controlling

Annual 

NMOC 

Reductions 

(Mg/yr)

Annual 

Methane 

Reductions

(million 

Mg/yr)

Annual 

Methane 

Reductions 

(million 

Mg CO2e 

/yr)

Baseline 954 559 395 49,600 7.7 193

The emission guidelines in the baseline are estimated to 

require control at 559 of the 954 affected landfills in 2014 and 

achieve reductions of 49,600 Mg/yr NMOC and 7.7 million Mg/yr

 32 Ibid, Table 8-1.

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methane (193 million Mg/yr CO2e). TheIn the baseline estimateswe 

estimate that 30 percent (559/1,832) of these existing landfills 

will operate emission controls in 2014 (1,832 is the number of 

landfills in the landfills dataset that had sufficient data to 

use in the preliminary cost and reduction analysis).

2. Other Programs Achieving Emission Reductions from Existing 

MSW Landfills 

Landfill owners and operators collect LFG for a variety of 

reasons: Toto control odor, to minimize fire and explosion 

hazards, to recover LFG to be used for energy recovery, to sell 

carbon credits, and to comply with local, state, or federal air 

quality standards. This section of this notice discusses several 

other majornon-EPA programs of which the EPA is aware. These 

reductions complement the reductions achieved by the current 

NSPS and emission guidelines framework.

i. State and Local Ordinances

The EPA is aware that some state or local ordinances 

require LFG combustion for odor or safety reasons. The number of 

landfills controlling under local ordinances is unknown. In 

addition, the state of California recently established methane 
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regulations33

ii. Market-based Mechanisms

to require a 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. 

LMOP maintains a voluntary national database of landfills 

and LFG energy projects, including information on which 

landfills have a GCCS in place. The EPA compared the list of 

landfills that are modeled to have installed a GCCS in 2014 in 

the NSPS/emission guidelines dataset to the list of landfills 

that are reported to have a GCCS installed in the LMOP database. 

While the NSPS/emission guidelines dataset estimates that 

approximately 550 landfills have installed controls to meet the

requirements of the NSPS or an approved state plan or federal 

plan implementing the emission guidelines, the LMOP database 

shows approximately 500 additional landfills as having installed 

controls, resulting in over 1,000 landfills estimated to have a 

GCCS installed.34

 

33 California Code of Regulations, title 17, subchapter 10, article 4, 

subarticle 6, sections 95460 to 95476, Methane Emissions from Municipal Solid 

Waste Landfills.

Approximately half of these 500 landfills 

exceed the design capacity of 2.5 million Mg and 2.5 million m3, 

but as of 2014, are not modeled to exceed the NMOC emission 
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threshold that dictates when a GCCS must be installed. Many of 

these systems may have been installed to recover energy and 

generate revenue through the sale of electricity or LFG. The 

LMOP database estimates that almost 200 of the 500 landfills 

with voluntary systems have an energy recovery component. Among 

landfills with larger design capacities, approximately 120 of 

the 260 landfills with a voluntary GCCS have an energy recovery 

component. Some landfills with voluntary systems may also 

receive revenues as a result of the creation of carbon credits. 

Data from the Climate Action Reserve indicates that more than 

100 LFG capture projects in 36 states have been issued credits 

known as Climate Reserve Tonnes (CRTs).35

D. What are the health and welfare effects of LFG emissions? 

1. Health Impacts of VOC and Various Organic HAP

The pollutant regulated under the landfills NSPS is “MSW 

landfill emissions.” Municipal solid waste landfill emissions, 

also commonly referred to as LFG, are a collection of air 

pollutants, including methane and NMOC, some of which are toxic. 

LFG generated from established waste (waste that has been in 

place for at least a year) is typically composed of roughly 50-

 34 See Sections III.BII.D.2 and III.DC of this notice for a detailed 

discussion of the modeling database and estimated reductions under the 

current federal regulatory framework. 35 Climate Action Reserve. Issued List of CRTs as of April 17, 2014. 

https://thereserve2.apx.com/myModule/rpt/myrpt.asp?r=112.
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percent methane and 50-percent CO2 by volume, with less than 1 

percent NMOC. The NMOC portion of LFG can contain a variety of 

air pollutants, including VOC and various organic HAP. VOC 

emissions are precursors to both fine particulate matter (PM2.5)

and ozone formation. Exposure to PM2.5 and ozone is associated 

with significant public health effects.36,37 PM2.5 is associated 

with health effects including premature mortality for adults and 

infants, cardiovascular morbidity such as heart attacks and 

respiratory morbidity such as asthma attacks, acute and chronic 

bronchitis, hospital admissions and emergency room visits, work 

loss days, restricted activity days and respiratory symptoms, as 

well as visibility impairment38. Ozone is associated with health 

effects including premature mortality, lung damage, asthma 

aggravation and other respiratory symptoms, hospital and 

emergency department visits, and school loss days, as well as 

injury to vegetation and climate effects39

 

36 U.S. EPA. 2009. “Integrated Science Assessment for Particulate Matter 

(Final Report).” EPA-600-R-08-139F. National Center for Environmental 

Assessment—RTP Division. Available at http://www.epa.gov/ncea/isa/.

. Nearly 30 organic HAP 

37 U.S. EPA. 2013. “Integrated Science Assessment for Ozone and Related 

Photochemical Oxidents (Final Report).” EPA-600-R-10-076F. National Center 

for Environmental Assessment—RTP Division. Available at 

http://www.epa.gov/ncea/isa/. 38 U.S. EPA. 2009. “Integrated Science Assessment for Particulate Matter 

(Final Report).” EPA-600-R-08-139F. National Center for Environmental 

Assessment—RTP Division. Available at http://www.epa.gov/ncea/isa/. 39 U.S. EPA. 2013. “Integrated Science Assessment for Ozone and Related 

Photochemical Oxidents (Final Report).” EPA-600-R-10-076F. National Center 

for Environmental Assessment—RTP Division. Available at 

http://www.epa.gov/ncea/isa/.
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have been identified in uncontrolled LFG, including benzene, 

toluene, ethyl benzene and vinyl chloride.40

2. Climate Impacts of Methane Emissions

In addition to the improvements in air quality and 

resulting benefits to human health and non-climate welfare 

effects discussed above, reducing emissions from landfills is 

expected to result in climate co-benefits due to reductions of 

the methane component of LFG. Methane is a potent GHG with a GWP

25 times greater than CO2.41

 

40 U.S. EPA. 1998. Office of Air and Radiation, Office of Air Quality Planning 

and Standards. “Compilation of Air Pollutant Emission Factors, Fifth Edition, 

Volume I: Stationary Point and Area Sources, Chapter 2: Solid Waste Disposal, 

Section 2.4: Municipal Solid Waste Landfills”. Available at: 

http://www.epa.gov/ttn/chief/ap42/ch02/final/c02s04.pdf.

Once emitted into the atmosphere, 

methane absorbs terrestrial , which accounts for methane’s 

stronger absorption of infrared radiation, which contributes to 

warming of per ton in the atmosphere but also its shorter 

lifetime (on the atmosphere, which over time leads to increased 

air and ocean temperatures, changes in precipitation patterns, 

melting and thawingorder of global glaciers and ice, 

increasingly severe weather events, such as hurricanes of 

greater intensity and sea level rise, among other impacts.a 

41 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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decade compared to centuries or millennia for carbon dioxide).42

According to the Intergovernmental Panel on Climate Change 

(IPCC) 5th Assessment Report, methane is the second leading longlived climate forcer after CO2 globally.43

As discussed in detail in the 2009 Endangerment Finding, 

climate change threatens public health in a number of ways: 

direct temperature effects, the effect of higher atmospheric CO2

concentrations on characteristics of air quality, and changes in 

vector-borne diseases. In addition to direct temperature health 

effects and climate change induced air quality effects, there is 

also the potential for increased mortality rates, injuries, 

infectious diseases and stress-related disorders resulting from 

more frequent extreme weather events. According to the 

assessment literature, under changing climate and environmental 

conditions there will also likely be an increase in the spread 

 

42 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.

43 Stocker, T.F., D. Qin, G.-K. Plattner, L.V. Alexander, S.K. Allen, N.L. 

Bindoff, F.-M. Bréon, J.A. Church, U. Cubasch, S. Emori, P. Forster, P. 

Friedlingstein, N. Gillett, J.M. Gregory, D.L. Hartmann, E. Jansen, B. 

Kirtman, R. Knutti, K. Krishna Kumar, P. Lemke, J. Marotzke, V. MassonDelmotte, G.A. Meehl, I.I. Mokhov, S. Piao, V. Ramaswamy, D.Randall, M. 

Rhein, M. Rojas, C. Sabine, D. Shindell, L.D. Talley, D.G. Vaughan and S.-P. 

Xie. 2013: “Technical Summary. In: Climate Change 2013: The Physical Science 

Basis. Contribution of Working Group I to the Fifth Assessment Report of the 

Intergovernmental Panel on Climate Change” [Stocker, T.F., D. Qin, G.-K. 

Plattner, M. Tignor, S.K. Allen, J. Boschung, A. Nauels, Y. Xia, V. Bex and 
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of serial episodes of food and water-borne pathogens among 

susceptible populations, depending on the pathogens’ survival, 

persistence, habitat range and transmissioncaused by human 

emissions of GHGs threatens public health in multiple ways. By 

raising average temperatures, climate change increases the 

likelihood of heat waves, which are associated with increased 

deaths and illnesses. While climate change also increases the 

likelihood of reductions in cold-related mortality, evidence 

indicates that the increases in heat mortality will be larger 

than the decreases in cold mortality in the United States. 

Compared to a future without climate change, climate change is 

expected to increase ozone pollution over broad areas of the 

U.S., including in the largest metropolitan areas with the worst 

ozone problems, and thereby increase the risk of morbidity and 

mortality. Other public health threats also stem from projected 

increases in intensity or frequency of extreme weather 

associated with climate change, such as increased hurricane 

intensity, increased frequency of intense storms, and heavy 

precipitation. Increased coastal storms and storm surges due to 

rising sea levels are expected to cause increased drownings and 

other health impacts. Children, the elderly, and the poor are 

 P.M. Midgley (eds.)]. Cambridge University Press, Cambridge, United Kingdom 

and New York, NY, USA.
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among the most vulnerable to these climate-related health 

effects. 

As with public health, there are multiple pathways in which 

GHG air pollution and resultant climate change affect climatesensitive economic sectors and environmental media. These 

sectors include agriculture; forestry; water resources; sea 

level rise in coastal areas; energy, infrastructure and 

settlements; and ecosystems and wildlife.

As documented in the 2009 Endangerment Finding, climate 

change caused by human emissions of GHGs also threatens public 

welfare in multiple ways. Climate changes are expected to place 

large areas of the country at serious risk of reduced water 

supplies, increased water pollution, and increased occurrence of 

extreme events such as floods and droughts. Coastal areas are 

expected to face increased risks from storm and flooding damage 

to property, as well as adverse impacts from rising sea level, 

such as land loss due to inundation, erosion, wetland 

submergence and habitat loss. Climate change is expected to 

result in an increase in peak electricity demand, and extreme 

weather from climate change threatens energy, transportation, 

and water resource infrastructure. Climate change may exacerbate 

ongoing environmental pressures in certain settlements, 

particularly in Alaskan indigenous communities. Climate change 
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also is very likely to fundamentally rearrange U.S. ecosystems 

over the 21st century. Though some benefits may balance adverse 

effects on agriculture and forestry in the next few decades, the 

body of evidence points towards increasing risks of net adverse 

impacts on U.S. food production, agriculture and forest 

productivity as temperature continues to rise. These impacts are 

global and may exacerbate problems outside the U.S. that raise 

humanitarian, trade, and national security issues for the U.S.

Methane is also a precursor to ground-level ozone, a 

health-harmful air pollutant. Additionally, ozone is a shortlived climate forcer that contributes to global warming. In 

remote areas, methane is a dominant precursor to tropospheric 

ozone formation.44 Approximately 4050 percent of the global 

annual mean ozone increase since preindustrial times is believed 

to be due to anthropogenic methane.45

 

44 U.S. EPA. 2013. “Integrated Science Assessment for Ozone and Related 

Photochemical Oxidents(Final Report).” EPA-600-R-10-076F. National Center for 

Environmental Assessment—RTP Division. Available at 

http://www.epa.gov/ncea/isa/.

Projections of future 

emissions also indicate that methane is likely to be a key 

45 Task Force on Hemispheric Transport of Air Pollution (HTAP). 2010. 

Hemispheric Transport of Air Pollution 2010. Informal Document No.10. 

Convention on Long-range Transboundary Air Pollution Executive Body 28th 

Session. ECE/EB.AIR/2010/10 (Corrected). Chapter 4, pp. 148-149.45 Myhre, G., 

D. Shindell, F.-M. Bréon, W. Collins, J. Fuglestvedt, J. Huang, D. Koch, J.-

F. Lamarque, D. Lee, B. Mendoza, T. Nakajima, A. Robock, G. Stephens, T. 

Takemura and H. Zhang, 2013: Anthropogenic and Natural Radiative Forcing. In: 

Climate Change 2013: The Physical Science Basis. Contribution of Working 

Group I to the Fifth Assessment Report of the Intergovernmental Panel on 

Climate Change [Stocker, T.F., D. Qin, G.-K. Plattner, M. Tignor, S.K. Allen, 
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contributor to ozone concentrations in the future.46 Unlike NOX

and VOC, which affect ozone concentrations regionally and at 

hourly time scales, methane emissions affect ozone 

concentrations globally and on decadal time scales given 

methane’s relatively long atmospheric lifetime compared to these 

other ozone precursors.47 Reducing methane emissions, therefore, 

canmay contribute to efforts to reduce global background ozone 

concentrations, human exposure to ozone and that contribute to

the incidence of ozone-related health effects around the 

world.48,49

IV. Topics for Which the EPA is Seeking Input

These benefits are global and occur in both urban and 

rural areas.

The EPA is considering several alternative approaches for 

achieving additional LFG emission reductions from existing MSW 

landfills. The EPA requests data and input regarding each of 

these approaches, or other alternative frameworks that should be 

considered for existing landfills. The EPA is specifically 

interested in input related to new technologies and data on 

costs and emission reductions for each of these technologies or 

 J. Boschung, A. Nauels, Y. Xia, V. Bex and P.M. Midgley (eds.)]. Cambridge 

University Press, Cambridge, United Kingdom and New York, NY, USA. Pg. 680. 46 Ibid. 47 Ibid. 48 West, J.J., Fiore, A.M. 2005. “Management of tropospheric ozone by reducing 

methane emissions.” Environ. Sci. Technol. 39:4685-4691.
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practices. The EPA is also interested in ideas regarding how 

these alternatives may be incorporated into a regulatory 

framework for existing landfills. Sections IV.A through IV.F of 

this notice describe and request input on alternative approaches 

for achieving additional LFG reductions from existing landfills. 

Since the landfills regulations were implemented in 1996, 

the EPA has become aware of implementation issues for which 

landfill owners and operators, as well as regulators, need 

clarification. In this notice, the EPA is also soliciting input

on the implementation issues. Section IV.G of this notice

describes and requests input on these implementation issues.

A. Taking Reductions in Methane Emissions Into Account in 

Reviewing the Emission Guidelines

In light of the Methane Strategy discussed in section II of 

this notice, the EPA is seeking input on the extent to which 

methane should be addressed under the revised emissions 

guidelines. The EPA is also requesting input on potential 

implementation issues associated with any adjustments that could 

be made to the current rule framework or any alternative 

regulatory frameworks that may achieve a larger fraction of 

methane emission reductions from existing landfills than the 

 49 Anenberg, S.C., et al. 2009. “Intercontinental impacts of ozone pollution 

on human mortality,” Environ. Sci. & Technol. 43: 6482-6487.
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current performance-based standard of a well-designed and welloperated GCCS.

B. Potential Changes to Regulatory Framework for Existing 

Sources

The EPA is considering potential changes within the current 

regulatory framework of the landfills regulations for existing 

sources that would achieve further emission reductions. This 

section outlines the current framework and identifies potential 

adjustments to that framework. The EPA is requesting input on 

these potential adjustments, the degree of emission reductions 

that could be achieved, corresponding cost and implementation.

1. Current Framework 

The landfills regulations in 40 CFR part 60, subparts Cc 

and WWW require an MSW landfill with a design capacity of 2.5 

million Mg and 2.5 million m3 or greater to install a GCCS once 

the emissions from the landfill meet or exceed 50 Mg NMOC per 

year. The landfill has 30 months to install and begin operating 

the GCCS. This 30-month “initial lag time” is the time period 

between when the landfill exceeds the NMOC emission rate 

threshold and when controls are required to be installed and 

started up. A landfill must expand the GCCS as more waste is 

added to the landfill. This “expansion lag time” is the amount 

of time allotted for the landfill to expand the GCCS into new 
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areas of the landfill (5 years for active areas and 2 years for 

areas that are closed or at final grade). When promulgated in 

1996, the best system of emission reduction for MSW landfills 

was determined to be a well-designed and well-operated landfill 

GCCS with a control device capable of reducing NMOC by 98

percent by weight. Enclosed combustion devices have the option 

of either reducing NMOC by 98 percent by weight or reducing NMOC 

emissions to 20 parts per million, dry volume. NMOC was 

established as a surrogate for LFG in the final rule.

Without any changes to the framework of the rule, over 950 

landfills are affected, and 691 are required to install controls

on or before 2023. These current requirements are estimated to 

result in NMOC emission reductions of 55,000 Mg/yr and methane 

emission reductions of 8.5 million Mg/yr (213 million Mg/yr

CO2e), on average over the next 10-year period (2014-2023). 

These reductions are expected to be achieved at an average cost 

effectiveness of approximately $7,200 per Mg NMOC or $46 per Mg 

methane ($1.8 per Mg CO2e). Additional information about these 

estimates can be found in the docketed memo Preliminary Cost and 

Emissions Impacts Analysis for Review of the MSW Landfills 

Emission Guidelines 2014.

Within the current framework of 40 CFR part 60, subparts Cc 

and WWW, several parameters could be adjusted to potentially 
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achieve additional emission reductions. Those parameters are the 

design capacity, the NMOC emissions threshold, and the timing of 

installing and expanding the GCCS. The EPA conducted a 

preliminary analysis as described below to estimate the 

emissions and cost implications of adjusting rule parameters. 

Modeling options that varied these parameters showed the 

following general incremental results as compared to the current 

regulatory framework over the next 10-year period (2014-2023).

These preliminary cost-effectiveness values presented later in 

this section IV.B include the costs to install and operate GCCS 

as well as any revenue from energy recovery as discussed in 

further detail in the docketed memorandum, “Methodology for 

Estimating Cost and Emission Impacts of MSW Landfills 

Regulations. 2014.” Installation, operation and maintenance of 

the GCCS represents over 99 percent of the annual costs, and 

although the costs presented here do not include testing and 

monitoring costs, those costs are expected to be nominal 

relative to the control costs.

i. Reducing or Eliminating the Design Capacity Threshold

Options that decrease the design capacity threshold would 

make more landfills subject to the rule. Such options also would 

increase the overall reporting burden because more landfills 

would be required to calculate and report their NMOC emission 
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rates. Landfills that exceed aany lower design capacity 

threshold and become subject to subpart XXX would also be 

required to obtain a Title V permit because sources subject to 

an NSPS must generally obtain a Title V permit. Only a few 

additional landfills would be required to install controls 

because landfills still must exceed the NMOC emission rate 

threshold before such controls are applied., and under the 

current threshold, about 72 percent of landfills over the design 

capacity threshold exceed the NMOC emissions rate. Thus, options 

that decrease the design capacity threshold without also 

lowering the NMOC emission threshold create additional reporting 

and permitting burden with minimal additional emission 

reductions. Modeling showed that if the EPA decreased the design 

capacity threshold to 2.0 million Mg or 2.0 million m3, then 

over 90 additional landfills would be affected by the rule and 

five additional landfills would require controls, resulting in 

NMOC reductions of 74 Mg/yr and methane emission reductions of 

11,500 million Mg/yr (287,000 Mg/yr CO2e). These reductions 

could be achieved at a cost effectiveness of approximately 

$9,900 per Mg NMOC or $64 per Mg methane ($2.6 per Mg CO2e).

The EPA also explored decreasing the NMOC emission 

threshold in conjunction with decreasing the design capacity. 

Modeling showed that if the EPA decreased the design capacity 
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threshold to 2.0 million Mg or 2.0 million m3 and reduced the 

NMOC emission threshold to between 34 and 40 Mg/yr, then 

approximately 90 additional landfills would be affected by the 

rule and 80 to 160 additional landfills would require controls, 

resulting in additional NMOC reductions of 2,100 to 3,200 Mg/yr

and methane reductions of 328,000 to 494,000 Mg/yr (8.2 to 12.3 

million Mg/yr CO2e). These additional reductions could be 

achieved at an incremental cost effectiveness of between $16,000 

and $18,000 per Mg NMOC or $100 to $115 per Mg methane ($4 to $5 

per Mg CO2e).

In addition, if the EPA were to remove the design capacity 

threshold, then a significant number of additional landfills 

would be subject to the rule. Out of the approximately 1,800 

existing landfills with sufficient data to include in the 

preliminary analysis for the review of the emission guidelines, 

over 850 have a design capacity of less than 2.5 million Mg or 

2.5 million m3. Without a design capacity threshold, the NMOC 

emission rate would be the only criterion for installing 

controls. Thus, these landfills would be required to begin 

calculating and reporting their NMOC emission rate. They would 

also be required to obtain a Title V permit. A smaller number of 

additional landfills would be required to install controls, 

because currently only those landfills below the design capacity 
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threshold that exceed the NMOC emission rate would require 

controls. Note that as landfills continue to add waste and 

continue to calculate and report the annual NMOC emission rate, 

over time, more landfills would be required to install controls, 

which would thus achieve additional emission reductions. The EPA 

requests input on whether or not adjustments to the design 

capacity threshold should be considered.

ii. Reducing NMOC Emission Threshold

Decreasing the NMOC emissions threshold would not change 

the number of landfills subject to the rule or affect the 

overall reporting burden. However, a lower NMOC emissions 

threshold would require more landfills to install controls. 

Although an NMOC emission threshold would continue to use NMOC 

as a surrogate for LFG, additional methane reductions could be 

achieved as a result of lowering the NMOC threshold, which is 

consistent with the President’s Methane Strategy as described in 

section II of this notice.

Modeling showed that if the EPA decreased the NMOC 

threshold to 40 Mg/yr NMOC, then approximately 80 additional 

landfills would require controls, resulting in additional NMOC 

reductions of 1,900 Mg/yr and methane reductions of 303,000 

Mg/yr (7.6 million Mg/yr CO2e) as compared to the current rule 

requirements. These additional reductions could be achieved at 
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an incremental cost effectiveness of approximately $16,000 per 

Mg NMOC or $100 per Mg methane ($4 per Mg CO2e). The EPA’s 

preliminary analysis did not include a reduction of NMOC 

threshold below 40 Mg/yr without also reducing the design 

capacity threshold. The preliminary emission reduction impacts 

of reducing both of these parameters are presented in section 

IV.B.1 of this notice. The EPA requests input on whether or not 

adjustments to the NMOC emission threshold should be considered.

iii. Adjustments to Initial or Expansion Lag Times

As mentioned above, “lag time” is the period between when 

the landfill exceeds the NMOC emission rate threshold and when 

controls are required to be initially installed (or expanded)

and started up. 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 

affect how much and when emission reductions would be achieved. 

Based on input received from commenters50

 

50 The EPA conducted outreach with small entities, state and local officials, 

and representative organizations, hereinafter referred to as commenters.

, large filling areas at 

modern landfill designs typically do not close before 7 years. 

Because the landfills regulations allow two options for 

expanding the GCCS (2 years after initial waste placement in 
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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 

larger existing landfills because the majority of landfills are 

complying with the 5-year deadline instead of the 2-year 

deadline. Some of the smaller landfills may achieve final grade 

in a shorter time period. Modeling showed that if the EPA 

decreased the initial lag time to 2 years, then four additional 

landfills would require control, resulting in an additional NMOC 

reduction of approximately 600 Mg/yr and methane reductions of 

88,000 Mg/yr (2.2 million Mg CO2e/yr) would be achieved as 

compared to the current rule framework. These additional 

reductions could be achieved at an incremental cost 

effectiveness of approximately $4,700 per Mg NMOC or $30 per Mg 

methane ($1.2 per Mg CO2e). 

Modifying the 5-year provision may also have a limited 

effect on emission reductions. Many landfills in wet climates 

are already installing wells ahead of the 5-year schedule for 

odor or energy recovery purposes. Modeling showed that if the 

EPA decreased the expansion lag time to 2 years, then an 

additional NMOC reduction of nearly 1,000 Mg/yr and methane 

reductions of 152,000 Mg/yr (3.8 million Mg/yr CO2e) could be 

achieved as compared to the current rule framework. These 
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additional reductions could be achieved at an incremental cost 

effectiveness of approximately $17,000 per Mg NMOC or $106 per 

Mg methane ($4.3 per Mg CO2e). 

The EPA received input from commenters expressing concern 

about the potential shortening of lag times. The comments 

indicated that 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 re-drilling 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 are not currently 

accounted for in the LFGcost model estimates and also increase 

the amount of system down time.

In addition to the implementation concerns, reducing the 

lag times would require more frequent mobilization of drill rig 

equipment, and purchase of GCCS infrastructure and system 

repairs, which could lead to higher costs. Note that the 

preliminary cost effectiveness estimates shown above do not 

include any cost adjustments to repair wells damaged in active 

areas. We seek input on how to account for these costs.
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Commenters also 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. The EPA requests input on the assumptions outlined above 

and whether or not adjustments to lag times should nonetheless

be considered. 

Horizontal Collectors. Horizontal LFG collection wells may 

provide some relief to the implementation concerns that have 

been raised, while also allowing for the wells to be installed 

more quickly after the waste is placed in the landfill. These 

types of wells are used in active fill areas and 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 
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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. Sufficient refuse is 

necessary in order to prevent air infiltration in the landfill. 

The time to accumulate sufficient waste is, however, often 

shorter than the time needed to install vertical wells, and can 

be as short as a few months after refuse is buried.51

The EPA is aware of several horizontal collector 

installations, including at several landfills in California

As a 

result, the installation of horizontal collectors could result 

in LFG being collected sooner.

52

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 (as discussed earlier in this section IV.B.1). 

and 

18 different landfills reporting 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.” 

 

51 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). 52 SCS Engineers, Technology and Management Options for Reducing Greenhouse 

Gas Emissions. Prepared for California Integrated Waste Management Board.
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Quickly bringing these collectors online has added the benefit 

of proactively addressing odor concerns at landfills. These 

systems are also useful in landfills that practice “overfilling,” where new waste is placed on top of a section of the 

landfill that was capped temporarily. Some implementation 

concerns with horizontal collectors have been expressed, 

particularly regarding their shorter lifetime than vertical 

wells and the need for more frequent replacement. 

The EPA requests input on the assumptions outlined above 

and whether adjustments to lag times should nonetheless be 

considered.

iv. Adjustments to the Length of Time That Control Equipment 

Must Remain Operational

The EPA is requesting input on the criteria and timing for 

capping or removing the GCCS. Under 40 CFR part 60, subpart WWW, 

a landfill may cap or remove the GCCS if the following three 

criteria are met: (1) the landfill is closed; (2) the GCCS has 

been in operation for 15 years; and (3) three successive tests 

for NMOC emissions are below the NMOC emission threshold 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 greater than 30 years after 

closure for a large modern landfill to emit less than the 50 Mg 
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per year NMOC emission threshold, and in turn qualify for 

capping or removing the GCCS. 

Although some commenters expressed concerns about the 

quantity of emissions after landfills have closed and the GCCS 

has ceased to operate, the preliminary analysis the EPA 

conducted demonstrated that approximately 130 landfills that 

have closed or will close by 2023 will require a GCCS to be 

operated for between 15 and nearly 70 years after the landfill 

has stopped accepting waste. The exact length of the period 

after landfill closure is commensurate with the size and 

corresponding emissions profile of each affected landfill. 

Nonetheless, the EPA is requesting input on whether there are 

other ways to ensure emissions are minimized in the later stages 

of a landfill’s lifecycle. Specifically, the EPA is seeking 

input on whether the three criteria listed above are 

appropriate, and if. We also seek input on alternative 

criteriaapproaches, such as consecutive quarterly measurements 

below a surface emission threshold should also be considered. 

Note that RCRA, specifically subpart F of part 258, also 

requires supplemental basic post-closure care to maintain cover 

integrity, which includes cover material requirements, design 

criteria for final cover systems, and post-closure care such as 

maintaining the integrity of the final cover and maintaining and 
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operating a gas monitoring system. The California landfill 

methane regulation53

v. Other Potential Adjustments

requires that systems stay in place until 

the landfill has operated the equipment for at least 15 years 

and the surface methane concentration measurement (instead of 

the measured NMOC emission cutoff rate) does not exceed a 500 

parts per million (ppm) instantaneous reading or a 25 ppm 

integrated reading. 

The California landfill methane regulation54

The Climate Action Reserve also incorporated waste-in-place 

criteria in version 4.0 of its Landfill Protocol.

uses a 

combination of waste-in-place and gas heat input capacity in 

lieu of design capacity and NMOC thresholds to determine which 

landfills are subject to GCCS requirements. Under the California 

regulation, a GCCS must 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. 

55

 

53 California Code of Regulations, title 17, subchapter 10, article 4, 

subarticle 6, section 95467, Methane Emissions from Municipal Solid Waste 

Landfills.

This protocol 

includes waste-in-place thresholds for landfills that recover 

54 California Code of Regulations, title 17, subchapter 10, article 4, 

subarticle 6, sections 95460 to 95476, Methane Emissions from Municipal Solid 

Waste Landfills.
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energy and those thresholds vary from 0.72 million Mg for 

landfills located in a non-arid area (receiving 25 inches or 

greater precipitation per year) to 2.17 million Mg for landfills 

located in an arid area (receiving less than 25 inches of 

precipitation per year) to determine what offset projects are 

eligible. Coupling a precipitation indicator with a waste-inplace threshold recognizes that LFG emission generation rates 

are affected by the quantity of waste disposed as well as the 

moisture present in the landfill, either due to the local 

climate, or other liquids added to a landfill, as discussed in 

earlier in this section IV.B.1. 

The EPA requests input on whether it should pursue an 

alternative set of thresholds to determine which landfills are 

subject to the revised emission guidelines and what criteria 

trigger the installation of a GCCS. 

vi. Potential Unique Treatment of Landfills Located in wetWet

Climates or Those Employing Leachate Recirculation or Other 

Liquids Addition

The EPA also seeks input on whether it should consider 

reducing the design capacity thresholds or initial and expansion 

lag times for landfills that are located in a wet climate or 

 55 Climate Action Reserve. Landfill Project Protocol. Version 4.0. June 29, 

2011.
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that recirculate leachate or add other liquids to the landfills 

to accelerate decomposition of the waste. Wetter wastes 

decompose more quickly than drier wastes and as a result 

generate more LFG in the short term. Therefore, it may be 

appropriate to require these landfills to install and expand the 

gas collection system sooner. Similarly, smaller landfills in 

wetter climates, or those employing leachate recirculation (or 

other liquids addition), may also generate earlier spikes in LFG

emissions that could exceed the NMOC threshold. Although these 

landfills are not affected by the current design capacity 

threshold of 2.5 million Mg and 2.5 million m3, if a smaller 

design capacity threshold or an alternative waste-in-place based 

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, or if an adjusted modeling 

provision were adopted (see section IV.E.1 of this notice), the 

EPA requests input 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 adds other liquids to the landfill.

vii. Definition of Modification
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The EPA in this ANPRM is seeking input on options to 

achieve additional emissions reductions from existing landfills 

under CAA section 111(d). In light of our interest in reducing 

the methane and NMOC components of LFG, the EPA is also seeking 

input on whether it is reasonable to review the definition of 

modification for landfills. A revision to the definition may 

result in additional reductions in LFG emissions at little or no 

additional cost because of the close relationship of control 

strategies that may apply to both modified landfills and 

existing sources. The EPA solicits input on changes that may be 

appropriate and whether these changes should be enacted to 

achieve additional emission reductions. 

C. Emission Reduction Techniques and GCCS Best Management 

Practices 

As mentioned previously, the EPA is considering potential 

changes within the current regulatory framework of the landfills 

regulations for existing sources that would achieve further 

emission reductions. This section discusses specific LFG control 

technologies and BMPs for GCCS and landfill operations to 

improve gas collection efficiencies. 

The EPA is soliciting input to evaluate the emission 

reductions achieved by the specific technologies and BMPs 

discussed later in this section to assess whether any 
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technologies and practices could be applied to the landfills 

regulations for existing sources to achieve further reductions 

of LFG.

The EPA will review the performance data, practical 

application, and cost of these BMPs or technologies to determine 

if and how they could be incorporated in conjunction with the 

current performance-based standard. Promotion of technologies 

and practices to achieve reductions of GHG from landfills 

complements the recently issued Methane Action Plan discussed in 

section II of this notice. 

The EPA is also requesting input on other technologies or 

BMPs that might be appropriate to encourage under the emission 

guidelines, the cost and emission reduction potential of each of 

these alternatives, and how each of these other approaches might 

be incorporated into the current rule framework or a new 

alternative rule framework.

1. Oxidation Technologies

The EPA is considering whether any emerging technologies 

may achieve additional emission reductions for existing 

landfills. As part of its consideration, the EPA will evaluate 

the extent to which the technology is adequately demonstrated

for existing landfills.
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The EPA is aware of several technologies that increase the 

methane oxidation rate, thereby reducing the amount of methane 

that could escape through the surface of the landfill. The 

principle of these technologies is the use of methanotrophic 

bacteria, commonly found in most soils and compost, to oxidize 

methane into water, carbon dioxide, and biomass.

A biocover is a cover material designed to enhance methane 

oxidation and is typically made of two layers — a permeable 

layer that consists of gravel, broken glass, sand or other media 

to evenly distribute the LFG to the oxidation media and an 

oxidation layer that typically consists of soil, compost, mulch 

or other organic media. The oxidation media contains 

methanotrophic bacteria from the waste decomposition process. 

One disadvantage of alternative cover technologies is their 

sensitivity to environmental conditions because the productivity 

of methanotrophic bacteria is highly dependent on the bacteria’s 

surroundings. Certain conditions, including temperature, 

moisture and pH, must be maintained to optimize methane 

oxidation rates.56

Methane oxidation occurs to some degree in various types of 

traditional landfill covers, including simple soil covers. Some 

 

56 BAAQMD. Greenhouse Gas Mitigation: Landfill Gas and Industrial, 

Institutional and Commercial Boilers, Steam Generators and Process Heaters.
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landfills use compost, yard waste and other organic wastes and 

materials as a type of naturally occurring biocover. Chipped 

rubber tires, Styrofoam and yard waste are other common types of 

waste that could serve as good methanotrophic media when mixed 

with soil or compost.57

The most common biocover in use at landfills is shredded 

yard waste used as alternative daily cover.58

The MSW landfills subpart of the GHGRP (40 CFR part 98, 

subpart HH) had used a default value of 10 percent for the 

amount of methane oxidized when calculating methane emissions 

from MSW landfills. However, recent research studies indicate 

that a default value of 10 percent may be underestimating the 

Biocovers 

consisting of naturally occurring and often readily available 

materials may provide a cost effective method to increase 

methane oxidation, thus decreasing methane emissions, at the 

surface of existing landfills. The EPA is requesting information 

to characterize the prevalence of the practice of using these 

types of naturally occurring biocovers at existing U.S. 

landfills and the costs to manage and apply these materials.

 Bay Area Air Quality Management District, prepared by URS Corporation. April 

2008.

57 BAAQMD. Greenhouse Gas Mitigation: Landfill Gas and Industrial, 

Institutional and Commercial Boilers, Steam Generators and Process Heaters.

Bay Area Air Quality Management District, prepared by URS Corporation. April 

2008.
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level of oxidation occurring at existing landfills and the 

amount of methane oxidized may be considerably higher, depending 

on cover type and other site-specific conditions.59 A 2009 

publication indicated that a literature review resulted infound

an average value of 35 percent for traditional landfill cover 

methane oxidation rates.60 A 2011 article documents a 4-year 

research study of over 37 seasonal sampling events at 20 

landfills across the United States with intermediate covers 

reported up to 37 percent average oxidation for soil covers.61 In 

addition, recent research demonstrates that daily soil covers 

oxidize methane to a greater degree than many low permeability 

final soil covers, suggesting oxidation rates of 20 to 55 

percent.62

 58 Sullivan, P. The Importance of Landfill Gas Capture and Utilization in the 

U.S. April 6, 2010.

As a result, recent final revisions to the GHGRP

published in the Federal Register on November 29, 2013 (78 FR 

71904), now allow for the use of higher oxidation values (25 

percent and 35 percent), in addition to the 10 percent value, if 

methane flux through the soil cover is of a certain amount and 

59 Sullivan, P. The Importance of Landfill Gas Capture and Utilization in the 

U.S. April 6, 2010.

60 Chanton, J.; Powelson, D.; Green, R. Methane oxidation in landfill cover 

soils, is a 10% default value reasonable? Journal of Environmental Quality.

38, 654–663 (2009). 61 Chanton, J.; Abichou, T.; Langford, C.; Hater, G.; Green, R.; Goldsmith, 

D.; Swan, N. Landfill Methane Oxidation Across Climate Types in the U.S. 

Environmental Science And Technology. 45, 313–319 (2011). 62 Sullivan, P. The Importance of Landfill Gas Capture and Utilization in the 

U.S. April 6, 2010.
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there is 24 inches or more of soil cover.63 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.64

The estimated cost of biocover installation (including 

geomembrane and gas distribution layer) for Yolo County (CA) 

Central Landfill’s full scale bioreactor was approximately 

$48,000 per acre. Biocover application costs may vary widely 

depending upon availability of material and the level of 

monitoring, and many materials would most likely be on site or 

easily obtained for free or for a nominal cost associated with

transporting the materials from a nearby or co-located yard 

waste or compost facility.65

RCRA Subtitle D addresses cover and capping requirements 

for MSW landfills. Specific requirements address the frequency 

and type of covers allowed, including provisions for requesting 

the use of alternative materials (40 part 258, subpart C). These 

operating parameters are in place to control disease vectors, 

 

63 If methane flux is less than 10 grams per square meter per day, then a 35 

percent oxidation fraction can be used. If methane flux is between 10 to 70 

grams per square meter per day, then a 25 percent oxidation fraction can be 

used. If methane flux is greater than 70 grams per square meter per day, then 

a 25 percent oxidation fraction can be used.

64 U.S. EPA. Available and Emerging Technologies for Reducing Greenhouse Gas 

Emissions from Municipal Solid Waste Landfills. June 2011.

65 BAAQMD. Greenhouse Gas Mitigation: Landfill Gas and Industrial, 

Institutional and Commercial Boilers, Steam Generators and Process Heaters.
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fires, odors, blowing litter and scavenging at the landfill, but 

are not covers that specifically promote oxidation of LFG. 

Design criteria for final cover systems (40 part 258, subpart F) 

were also established to minimize water infiltration and erosion 

of the landfill, rather than release of LFG or its constituents. 

Rules regarding the use of daily, intermediate and final cover 

are governed by RCRA Subtitle D; however, research indicates 

that biocovers may help to reduce emissions of methane, a 

primary constituent of LFG. 

Another method for increasing the oxidation rate is to 

route passively vented LFG through a vessel containing methaneoxidizing media, commonly referred to as a biofiltration beds or 

biofilters. Biofilter media have included compost or chipped 

yard waste mixed with recycled shredded tires or Styrofoam

peanuts as well as sand and soil mixtures. Choosing the proper 

media with sufficient gas conductivity is important to reduce 

the possibility of back pressure in the landfill.66

 Bay Area Air Quality Management District, prepared by URS Corporation. April 

2008.

Biofilters 

have been tested for use at landfills over only the past 10 to 

15 years. Studies of passively-aerated methane biofilters have 

66 BAAQMD. Greenhouse Gas Mitigation: Landfill Gas and Industrial, 

Institutional and Commercial Boilers, Steam Generators and Process Heaters.

Bay Area Air Quality Management District, prepared by URS Corporation. April 

2008.
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shown methane oxidation rates vary widely by type of biofilter 

media but could reach values between 19 and 98 percent.67,68

Biofilters are likely feasible for use at small existing 

landfills or existing landfills with passive gas collection 

systems due to the size of the biofiltration bed required to 

treat the mixture of air and LFG. Due to the nature of passive 

gas collection systems, this technology lacks the ability to 

control and monitor the oxidation of methane in the LFG.69

No data exist on the long-term performance, effectiveness, 

or maintenance requirements of biocovers or biofilters.

In 

general, biofilter costs are expected to be lower than biocover 

costs due to their smaller scale and utilization of existing 

passive vents.

70,71,72

 

67 Abichou, T.; Chanton, J.; Powelson, D. Field Performance of Biocells, 

Biocovers, and Biofilters to Mitigate Greenhouse Gas Emissions from 

Landfills. Florida Center for Solid and Hazardous Waste Management, 

University of Florida. March 2006.

Therefore, 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 also 

68 Morales, J.J. Mitigation of Landfill Methane Emissions from Passive Vents 

by Use of Oxidizing Biofilters. Fall 2006. 69 U.S. EPA. Available and Emerging Technologies for Reducing Greenhouse Gas 

Emissions from Municipal Solid Waste Landfills. June 2011.

70 U.S. EPA. Available and Emerging Technologies for Reducing Greenhouse Gas 

Emissions from Municipal Solid Waste Landfills. June 2011.

71 Abichou, T.; Chanton, J.; Powelson, D. Field Performance of Biocells, 

Biocovers, and Biofilters to Mitigate Greenhouse Gas Emissions from 

Landfills. Florida Center for Solid and Hazardous Waste Management, 

University of Florida. March 2006.
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seeking input on biocover parameters and their effect on 

oxidation. Such parameters may include depth, soil 

characteristics, measurement and their affect on percent 

oxidation. The EPA is also seeking input on appropriate 

mechanisms to monitor the performance of these alternatives.

2. Best Management Practices

The EPA is considering how certain BMPs that achieve 

additional emission reductions for existing landfills may be 

encouraged under a revised regulatory framework. The EPA seeks 

input on how to demonstrate that the BMPs are properly 

implemented and what additional maintenance records or other 

requirements might demonstrate that the BMPs can ensure the same 

level of environmental protection as the current framework. The 

EPA also invites input on other requirements that could be 

adjusted to encourage BMPs. 

i. LFG Collection from Leachate Removal Systems

The EPA is aware of landfills that have connected the LFG

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.73

 72 Yazdani, R, and Imhoff, P. Contractor’s report to CalRecycle: Biocovers at 

Landfills for Methane Emissions Reduction Demonstration. October 2010. 73 SCS Engineers, Technology and Management Options for Reducing Greenhouse 

Gas Emissions. Prepared for California Integrated Waste Management Board. 

Prepared by SCS Engineers. April 2008.
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The efficiency of capturing LFG emissions through this BMP 

depends on the efficiency of both the LFG collection system and 

the leachate recirculation system. Section 60.752(b)(2)(i)(D) of 

subpart WWW 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 sitespecific, the design plan has the flexibility to include 

collection of LFG from leachate collection systems.

The cost of each connection of GCCS to a leachate removal 

system would include $400 to $650 for a LFG wellhead and $10 to 

$15 per foot for a 3- or 4-inch HDPE pipe (2008 cost 

estimates).74

 

74 California Integrated Waste Management Board, Technologies and Management 

Options for Reducing Greenhouse Gas Emissions From Landfills, April 2008.

However, there are currently no broad mandates for 

requiring gas collection from leachate removal systems. The EPA 

requests input on the efficacy and costs of enhancing gas 

collection systems to collect LFG from leachate removal or 

storage systems. The EPA also requests information 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 
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when the use of an enhanced gas collection system that collects 

LFG from the leachate removal system may be appropriate.

ii. Preventing Waterlogged Wells

The EPA is also consideringseeks input on requiring a gas 

collection system to more proactively prevent waterlogged wells, 

perhaps through the use of leachate removal pumps or alternative 

GCCS infrastructure. Leachate and condensate can accumulate in 

collection wells, blocking LFG capture. Because a flooded well 

cannot collect gas, fixing a flooded well would have a high 

emission reduction potential. 

The most practical and cost effective method for keeping 

liquid out of gas extraction wells is to prevent its entry in 

the first place by ensuring proper sealing and grading at the 

surface. Infiltration of leachate from within the waste mass is

more difficult to control. Once liquid is inside the well, it 

often must be removed via pumping to restore the gas collection 

capability of the well. When performed in conjunction with 

effective leachate removal, it may be possible to dewater wells 

with a portable pump and a mobile storage tank that can be used 

to transport liquid removed from the well to a suitable leachate 

disposal point. Multiple iterations of dewatering could be 

required at each well because liquid often seeps back into the 

well after pumping. While labor intensive, this approach 
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alleviates the need for a dedicated pump and piping at multiple 

wells. If liquid accumulation in wells is an ongoing issue, then 

a dedicated pumping system may be suitable. Long term costs for 

a dedicated pumping system are still high, including the initial 

cost of pumps and piping, as well as ongoing operation and 

maintenance costs and disposal of the leachate. A single well 

dewatering pump system could cost over $3,000,75

Another method for reducing GHG emissions at landfills with 

waterlogged wells is to install a surface collector. A surface 

collector usually consists of perforated pipes laid across the 

top of the waste mass and covered by an impermeable geomembrane 

or by final cover. Surface collectors can be used to collect gas 

from a wet landfill where traditional horizontal and vertical 

wells fail due to water infiltration. Surface collectors can be 

used with or instead of horizontal collector systems.

but could also 

have a high impact onimprove LFG collection and GHG emission 

reduction.

76

 

75 Kaminski, D. and M. Varljen. Increasing LFG Collection Rates Using Gas Well 

Dewatering Systems: Lessons Learned. 15th Annual LMOP Conference. January 

2012. 

Because 

surface collectors are installed after final waste acceptance, 

they are not effective in controlling LFG emissions while the 

landfill is open and accepting waste. Surface collectors also do 

76 California Integrated Waste Management Board, Technologies and Management 

Options for Reducing Greenhouse Gas Emissions From Landfills, April 2008.
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not apply a vacuum into the waste so they are only effective at 

controlling gas that has escaped other collection systems. Their 

impact on emissions is therefore expected to be low in cases 

where a well-designed and well-operated LFG collection system 

already exists. The overall cost of surface collectors is 

comparatively high due to additional geomembrane material costs, 

if they are not already required by regulations. One 2008 study 

estimates the cost of installing a geomembrane to be $40,000 to 

$50,000 per acre of landfill surface. If a landfill already has 

a geomembrane, the added cost would be $25 to $35 per linear 

foot for a 6-foot deep trench and gravel backfill.77

Wellhead operating parameters in 40 CFR part 60, subpart 

WWW 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 help identify any inoperable wells 

resulting from flooding. Surface emissions monitoring would also 

help identify any elevated methane levels resulting from an 

inoperable well. Because some of the wells at existing landfills 

may have been installed for 15 years or more, the EPA requests 

 

77 California Integrated Waste Management Board, Technologies and Management 

Options for Reducing Greenhouse Gas Emissions From Landfills, April 2008.
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input 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 monitoring 

systems in 40 CFR part 60, subpart WWW are deficient for 

identifying flooded wells, the EPA also asks for input on 

whether any additional recordkeeping, such as periodic 

measurement of liquid levels in gas wells, might be useful to 

identify flooded wells that are not collecting gas. The EPA 

requests input on whether any more specific corrective action 

guidance should be developed, such as the need to dewater the 

well or employ alternative GCCS technologies such as surface 

collectors if a flooded well is identified. 

iii. Redundant Seals

The EPA is also considering a BMP of requiring redundant 

seals and the use of enhanced sealing materials on wellheads. 

One study includes a survey using a forward-looking infrared 

surveycamera suggesting that LFG wellheads and other surface 

penetrations present high potential for concentrated leaks of 

organic compounds.78

 

78 ARCADIS. Quantifying Methane Abatement Efficiency at Three Municipal Solid 

Waste Landfills. Prepared for U.S. EPA/ORD. January 2012.

The use of advanced seals at wellheads may 

help to ensure that the well can apply sufficient vacuum to the 
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landfill to facilitate gas extraction while preventing leaks of 

LFG to the atmosphere. The design for vertical wells typically 

includes the use of bentonite or bentonite soil mixtures near 

the surface as part of the well boring backfill to reduce the 

potential for air to be pulled into the well.79

Because a good seal is critical for proper well 

performance, multiple seals are often used. One reference 

indicates that manyMany engineers already require two and 

sometimes three seals in a well when preparing design plans for 

GCCS.

Compacted 

backfill soil can also be considered, but may not be practicable 

and adds risk of damaging the well casing pipe. A well’s 

connecting pipes are typically sealed using three different 

techniques: (1) Bentonite clay seal, (2) compacted clay seal or 

(3) plastic well bore seal.

80

 

79 California Integrated Waste Management Board, Technologies and Management 

Options for Reducing Greenhouse Gas Emissions From Landfills, April 2008.

However, for wells that are not properly sealed, their 

zone of influence is likely reduced, resulting in LFG between 

wells not being collected. In such cases, the effect on 

emissions reduction is high while the relative cost of adding 

80 Ibid.
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seals is low. Costs can range from $500 to $2500 per well based 

on 2008 estimates depending on the type of seal used.81

Because the design plan is not prescriptive and instead 

contains design and operational standards that are sitespecific, the design plan has the flexibility to determine the 

number or type of seals in order to accommodate the conditions 

and climates at different landfills. 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. The design plan, coupled with 

wellhead and surface monitoring requirements, ensures that leaks 

from wells are minimized. The EPA is soliciting input on what 

mechanisms, if any, might be appropriate to further promote or 

mandate enhanced seals in this emission guidelines review.

iv. Early Installation of Final Cover

Early installation of final cover systems can also reduce 

methane emissions. Current rules for landfills under RCRA 

Subtitle D require intermediate cover (typically at least 12 

inches of native soil) to be installed in areas of the landfill 

that are no longer receiving waste or will not be used for over 

12 months within 180 days of final waste placement (40 CFR part 

 

81 California Integrated Waste Management Board, Technologies and Management 

Options for Reducing Greenhouse Gas Emissions From Landfills, April 2008.81
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258, subpart C). The final cover system must consist of an 

infiltration layer of at least 18 inches of earthen material 

covered by an erosion layer of at least 6 inches of earthen 

material that is capable of sustaining native plant growth. An 

alternative cover design may be used as long as it provides 

equivalent protection against infiltration and erosion (40 CFR 

part 258, subpart F). Once a landfill has received its final 

shipment of waste, it must begin closure operations within 30 

days. A landfill, however, may delay closure for up to 1 year if 

additional capacity remains. Any further delays after 1 year 

require approval from the appropriate state agency. After 

beginning, all closure activities must be completed within 180 

days.

Despite these rules, landfill operators often leave 

intermediate cover in place for years or even decades and 

intermediate cover frequently is the only cover on the majority 

of the landfill surface. Recent studies indicate that 

installation of intermediate and final cover has a direct and 

significant effect on LFG emissions.82

 Ibid.

Intermediate cover 

significantly reduces emissions compared to daily cover on 

working faces. Final cover has the ability to reduce emissions 
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even further compared to intermediate cover. By installing these 

more rigorous cover systems sooner, significant emissions may be 

prevented from being released. Furthermore, final cover has been 

shown to increase LFG collection efficiency at landfills with a 

gas collection system.83

3. Organics Diversion and Source Separation 

Early installation of cover should not 

incur any additional cost to the landfill as long as waste 

acceptance or placement plans do not change after the cover 

(particularly final cover) is installed. Early installation of 

cover could result in a cost savings due to the general increase 

in the cost of materials over time and the added gas collection 

realized when more rigorous cover systems are installed –

especially if the gas is collected for beneficial use. 

LFG is a by-product of the decomposition of organic 

material in MSW under anaerobic conditions in landfills. The 

amount of LFG created primarily depends on the quantity of waste 

and its composition and moisture content, as well as the design 

and management practices at the site. Decreasing the amount of 

organics disposed in landfills would decrease the generation of 

LFG. 

 82 Goldsmith et al., Methane Emissions from 20 Landfills Across the United 

States Using Vertical Radial Plume Mapping, Journal of the Air & Waste Mgmt. 

Association, 62:2, 183-197 (2012).
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Organic materials are historically the largest component of 

materials discarded in the MSW stream, constituting nearly 49 

percent of discarded material in 2012. Food waste is the largest 

portion of the organic materials, followed by paper and 

paperboard, yard trimmings and wood wastes.84 Material recovery, 

including composting and recycling, has been increasing over 

time for all materials, except rubber and leather. For example, 

the percent of paper and paperboard that is recovered has 

increased from 16.9 percent in 1960 to 62.5 percent in 2012. The 

amount of recovered yard trimmings has increased from negligible 

amount in 1960 to 57.7 percent in 2012. Recovered food waste has 

increased less significantly from negligible amounts in 1960 to 

4.8 percent in 2012.85

Although material recovery has increased over time, there 

is potential to further increase the recovery of materials. Yard 

trimmings, paper, and paperboard recovery already exceed 50 

percent of the generated amount, but states and cities with 

vigorous recovery programs have proven that a greater percentage 

 83 Barlaz et al., Controls on Landfill Gas Collection Efficiency: 

Instantaneous and Lifetime Performance, Journal of the Air & Waste Mgmt. 

Association, 59, 1399-1404 (2009). 84 U.S. EPA, Municipal Solid Waste Generation, Recycling, and Disposal in the 

United States Tables and Figures for 2012. February 2014.

http://www.epa.gov/waste/nonhaz/municipal/pubs/2012_msw_dat_tbls.pdf.

85 U.S. EPA, Municipal Solid Waste Generation, Recycling, and Disposal in the 

United States Tables and Figures for 2012. February 2014.

http://www.epa.gov/waste/nonhaz/municipal/pubs/2012_msw_dat_tbls.pdf.
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recovery is possible. Recovery is still a small percentage of 

the amount of generated waste for some organic materials; for 

example, only 4.8 percent of generated food waste is recovered 

and only 15.2 percent of wood is recovered. 

Organic waste diversion regulations and zero waste 

programs are currently in effect in multiple U.S. states and 

cities, with 183 municipalities providing separate curbside 

collection of residential food waste.86 For example, state 

programs in California, Connecticut, and Massachusetts focus on 

diversion from commercial or certain multifamily residential 

waste generators.87,88,89 Vermont’s Universal Recycling Law 

implements a phased material ban beginning in 2016 for leaf and 

yard debris and food waste in 2020. City ordinances in New York 

City and Portland, Oregon, mandate materials separation from 

commercial and multifamily generators.90,91

 

86 Residential Food Waste Collection in the U.S. Biocycle. 54:3, 23, March 

2013.

Ordinances in Seattle 

87 California Code of Regulations, title 14, division 7, chapter 9.1, article 

4, subarticle 6, section 18835, Mandatory Commercial Recycling. 

http://www.calrecycle.ca.gov/recycle/commercial/

88 General Statutes of Connecticut, title 22a, chapter 446d, sections 22a226e, Recycling of Source-Separated Organic Materials. 

http://cga.ct.gov/2014/sup/chap_446d.htm#sec_22a-226e 89 Code of Massachusetts Regulations, title 310 CMR 19.000. January 2014 

amendments. http://www.mass.gov/eea/docs/dep/service/regulations/wbreg14.pdf 90 City of Portland Administrative Rules, Business Solid Waste, Recycling and 

Composting, ENN-2.06 http://www.portlandonline.com/auditor/?c=27430&a=294923 91 Administrative Code of the city of New York. Title 16, chapter 3, 

subchapter 2, section 1 (16-306.1). 

http://legistar.council.nyc.gov/LegislationDetail.aspx?ID=1482542&GUID=DDD940

82-C0E5-4BF9-976B-BBE0CD858F8F
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and San Francisco extend the separation mandate to single family 

dwellings.92,93

In the 1996 Landfills NSPS Background Information Document 

(page 1-25) the EPA “decided not to include materials separation 

requirements within the final rules because the EPA continues to 

believe RCRA and local regulations are the most appropriate 

vehicle to address wide-ranging issues associated with solid 

waste management for landfills.” 

Although the EPA is not requesting input on mandating

source separation under the upcoming emission guidelines review, 

the EPA is soliciting input and ideas for encouraging organic 

waste diversion under the revised emission guidelines, including 

the specific mechanisms described below and in section IV.E of 

this notice or other ideas in general.

One method to encourage organic waste diversion under the 

revised emission guidelines is to provide rule exemptions for 

landfills diverting 100 percent of organic wastes. The emission 

threshold determination provisions currently in 40 CFR part 60, 

subpart WWW allow non-degradable wastes to be excluded from the 

 

92 San Francisco Environment Code. Chapter 19, sections 1901-1912. Mandatory 

Recycling and Composting Ordinance. 

http://www.sfenvironment.org/sites/default/files/policy/sfe_zw_sf_mandatory_r

ecycling_composting_ord_100-09.pdf 93 Seattle Municipal Code. Chapters 21.40 and 21.76. 

http://www.seattle.gov/util/MyServices/FoodYard/BldgOwnersManagers_FoodYard/i

ndex.htm
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total waste mass when computing the NMOC emission rate. If only 

non-degradable wastes were accepted, then the waste inputs for 

the model would be zero, the emission thresholds would not be 

exceeded, and thus GCCS would not be required. The EPA solicits 

input on the methane emission reductions from organic and 

inorganic waste diversion and whether adjustments should be made 

to the annual NMOC reporting requirements for landfills not 

accepting organic materials.

4. Encouraging New Technologies and Practices 

The EPA understands that the technologies, BMPs, and source 

separation practices discussed above can achieve reductions in 

emissions from landfills. The EPA is seeking input on whether 

the use of any of the technologies or practices discussed in 

this section in conjunction with a well-designed and welloperated GCCS should be considered as the EPA reviews the 

emission guidelines. 

Section IV.E of this notice discusses other mechanisms to 

encourage wider use of these technologies and practices such as 

emission threshold determination flexibilities. 

5. Gas Control System Technology

Subpart WWW of 40 CFR part 60 currently requires all 

control devices other than enclosed combustion devices to 

demonstrate 98-percent reduction by weight of NMOC. Enclosed 
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combustion devices have the option of reducing emissions to 20 

ppm, dry volume of NMOC, as hexane. Both enclosed and nonenclosed flares as well as a suite of other energy recovery 

devices are used to meet the control requirements under the 

current regulatory framework.

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 LFG 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.”94

 

94 U.S. EPA, Parameters for Properly Designed and Operated Flares, Report for 

Flare Review Panel, April 2012.

In the draft 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. None of the flare performance data 

used in the report comes from flares used at MSW landfills, 

however, and the report 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, 
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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, we solicit input and additional 

information on flare performance specifically for this source 

category. 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 minimization practices; and existing flare 

monitoring systems. 

D. Alternative Monitoring, Reporting, and Other Requirements

In addition to the technologies, BMPs, and other approaches 

discussed in section IV.C of this notice, the EPA is considering 

whether alternative monitoring and reporting requirements would 

be appropriate for existing landfills. These alternative 

approaches address concerns that have arisen in implementation 

of subpart WWW and state and federal plans implementing subpart 

Cc and provide an opportunity to increase the effectiveness of 

the regulation.

1. Wellhead Monitoring

The EPA is requesting public input on alternative wellhead 

monitoring requirements. Commenters have expressed concerns 

about the ability to consistently meet these parameters. One 
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alternative monitoring provision could be in the form of an 

exclusion from the temperature and oxygen/nitrogen monitoring 

requirements, or a reduction in the frequency of monitoring. For 

example, the EPA could reduce the frequency of wellhead 

monitoring for these three parameters (temperature and 

oxygen/nitrogen) from monthly to a quarterly or semi-annual 

schedule. Owners or operators would continue to monitor the 

wellhead for negative pressure. 

The EPA is specifically requesting input on whether any 

such adjustment should apply only to landfills that beneficially 

use LFG, and if so whether there should be a threshold for the 

quantity of LFG put to beneficial use above which sources would 

qualify for alternative wellhead monitoring (and below which 

they would not), or whether the beneficial use of any quantity 

of the recovered LFG should qualify for alternative wellhead 

monitoring. Alternatively, the EPA is requesting input on 

whether it would be more appropriate to require a certain 

percentage of the overall recovered LFG to be beneficially used 

in order to exempt landfills from or reduce the frequency of the 

wellhead monitoring requirements. 

If EPA were to limit adjusted monitoring to landfills that 

beneficially use LFG, these alternatives could encourage new 

landfills to beneficially use LFG. Both of these alternative 
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options (exclusion or reduced monitoring frequency) would 

provide monitoring relief to these landfills. Landfill owners 

and operators must continue to operate their GCCS in a manner 

that collects the most LFG and minimizes losses of LFG through 

the surface of the landfill. In addition, landfills would still 

have to prepare and submit to the regulating authority a gas 

collection design plan, prepared by a professional engineer. 

Subparts Cc and WWW of 40 CFR part 60 require landfill 

owners and operators to operate each interior wellhead in the 

collection system with a LFG temperature less than 55°C and with 

either a nitrogen level less than 20 percent or an oxygen level 

less than 5 percent. Compliance with these requirements is 

demonstrated through monthly monitoring. Instead of having the 

landfill owner or operator conduct monthly monitoring of 

temperature and nitrogen/oxygen at the wellheads, the EPA is 

requesting input on relying on landfill surface emission 

monitoring requirements in combination with maintenance of 

negative pressure at wellheads to indicate proper operation of 

the GCCS and minimization of surface emissions. The potential 

removal of the temperature and nitrogen/oxygen operational 

standards and associated wellhead monitoring requirements for 

these three parameters would be complemented by the addition of 
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the surface monitoring provisions discussed in section IV.D.2 of 

this notice. 

Given recent technological advancements in data storage and 

transmission, the EPA is also considering an alternative to 

automate the wellhead monthly monitoring provisions. Automation 

could reduce long-term burden on landfill owner/operators as 

well as state authorities by allowing for more frequent, but 

less labor-intensive, data collection through the use of a 

system consisting of remote wellhead sensors (i.e., thermistors, 

electronic pressure transducers, oxygen cells) and a centralized 

data logger. 

The use of continuous monitoring would allow more immediate 

detection and repair. This would eliminate the time between when 

the exceedance of the parameter occurs and when it is detected. 

It could also improve enforceability of the rule by allowing 

inspectors to review information on the data logger in real time 

during a site visit. Another advantage to automating the 

monitoring is that it could provide flexibility for 

incorporating additional parameters into the monitoring program. 

The EPA is soliciting input on this alternative in general, 

including: (1) The types of parameters that are best suited for 

an automated monitoring alternative; (2) examples of successful 

automated monitoring programs at MSW landfills and their 
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associated costs; (3) additional considerations for equipment 

calibration; and (4) input on any averaging times that might be 

appropriate to determine when one or more monitored parameters 

have been exceeded.

2. Surface Emissions Monitoring. 

The EPA is requesting input on potential alternative 

approaches to the surface emission monitoring specified in 40 

CFR part 60, subpart WWW. Subpart WWW collection and control 

requirements are intended for landfills to maintain a tight 

cover that minimizes any emissions of LFG through the surface. 

The surface emissions monitoring procedures in subpart WWW 

require quarterly surface emissions monitoring to demonstrate 

that the cover and gas collection system are working properly. 

The operational requirements in subpart WWW (40 CFR 60.753(d)) 

specify that the landfill must “* * * operate the collection 

system so that the methane concentration is less than 500 parts 

per million above background at the surface of the landfill. To 

determine if this level is exceeded, the owner or operator shall 

conduct surface testing around the perimeter of the collection 

area and along a pattern that traverses the landfill at 30 meter 

intervals and where visual observations indicate elevated 

concentrations of LFG, such as distressed vegetation and cracks 

or seeps in the cover.”
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Subpart WWW of 40 CFR part 60 includes provisions for 

increased monitoring and corrective procedures if readings above 

500 ppm are detected. Instrumentation specifications, monitoring 

frequencies, and monitoring patterns are structured to provide 

clear and straightforward procedures that are the minimum 

necessary to assure compliance. 

We are requesting public input on potential alternatives to 

the surface monitoring procedures in 40 CFR part 60, subparts Cc 

and WWW. Potential alternatives could include provisions such as 

those in the California landfill methane regulation95

We are requesting input on reducing the interval for the 

walking pattern that traverses the landfill from 30 meters (98 

ft.) to 25 ft. We are also requesting input on the addition of 

an average methane concentration limit of 25 ppm as determined 

by integrated surface emissions monitoring. This would be in 

addition to the 500 ppm emission concentration as determined by 

instantaneous surface emissions monitoring. Integrated surface 

and include 

changing the walking pattern for inspecting the surface of the 

landfill, adding an integrated methane concentration 

measurement, and allowing sampling only when wind is below a 

certain speed. 
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emissions monitoring provides an average surface emission 

concentration across a specified area. For integrated surface 

emissions monitoring, the specified area would be individually 

identified 50,000 square foot grids. A tighter walking pattern 

and the addition of an integrated methane concentration would 

more thoroughly ensure that the collection system is being 

operated properly, that the landfill cover and cover material 

are adequate, and that methane emissions from the landfill 

surface are minimized. As part of these potential changes, the 

EPA is also requesting input on not allowing surface monitoring 

when the average wind speed exceeds 5 miles per hour or the 

instantaneous wind speed exceeds 10 miles per hour because air 

movement can affect whether the monitor is accurately reading 

the methane concentration during surface monitoring. We are 

considering this change because measurements during windy 

periods are usually not representative of emissions.

We are also soliciting information and associated data on 

the cost and assumptions for conducting enhanced surface 

monitoring as described here. Several factors contribute to the 

cost of enhanced surface monitoring. Monitoring along a traverse 

with a 25 ft. interval would increase monitoring time, and,

 95 California Code of Regulations, title 17, subchapter 10, article 4, 

subarticle 6, sections 95460 to 95476, Methane Emissions from Municipal Solid 
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thus, the labor costs, compared to monitoring along a 30 meter 

(98 ft.) interval. Monitoring along the tighter traverse pattern 

would take approximately four times as long, because the 

distance is approximately four times when covering a 50,000 

square foot grid. For a landfill to conduct the integrated 

surface emissions monitoring, the EPA assumes the landfill would 

rent a handheld portable vapor analyzer with a data logger. The 

data logger would be necessary to obtain an integrated reading 

over a single 50,000 square foot grid. However, the EPA does not 

expect that requiring an integrated methane concentration would 

add significant cost because landfills could use the same 

instrument that they currently use for the instantaneous 

readings. These instruments can be programmed to provide an 

integrated value as well as an instantaneous value. 

The EPA recognizes that while these provisions could 

minimize surface emissions, the actual reduction in emissions is 

difficult to quantify. Surface monitoring is a labor intensive 

process and tightening the grid pattern would increase costs. 

Thus, the EPA is soliciting input on techniques and data to 

estimate the reductions associated with enhanced surface 

monitoring. 

 Waste Landfills.
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The EPA is also requesting input on allowing the use of 

alternative remote measurement and monitoring techniques for 

landfills that exceed the surface monitoring concentrations in 

40 CFR part 60, subpart Cc. The EPA would like information to 

determine whether to allow these alternative techniques to be 

used to demonstrate that surface emissions are below the 

specified methane surface concentrations. Alternative remote 

measurement and monitoring techniques may include radial plume 

mapping (RPM), optical remote sensing, Fourier Transform 

Infrared (FTIR) spectroscopy, cavity ringdown spectroscopy 

(CRDS), tunable diode laser (TDL), tracer correlation, 

micrometeorological eddy-covariance, static flux chamber or 

differential absorption. The EPA is also seeking input on the 

frequency of testing and the format of the standard if we allow 

the use of these technologies as an alternative to average 

surface concentrations as measured by Method 21. Incorporation 

of these technologies would require a change in format of the 

standard to be consistent with the technology.

3. Alternative Monitoring Provisions for LFG Treatment

The EPA is requesting input on defining treatment system as 

a system that filters, dewaters and compresses LFG. This 

alternative approach would be consistent with public commenters 

on previous landfills notices (67 FR 36475, May 23, 2002; 71 FR 
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53271, September 8, 2006). It is also consistent with input from 

participants in governmental outreach, who stated that the 

extent of filtration, de-watering and compression can be site 

dependent, and that different sites require different levels of 

gas treatment to protect the combustion devices that use treated 

LFG as a fuel and ensure good combustion. The alternative 

definition of treatment system would allow the level of 

treatment to be tailored to the type and design of the specific 

combustion equipment in which the LFG is used. If treatment 

system was defined in this manner, owners/operators would need 

to identify monitoring parameters and keep records that 

demonstrate that such parameters effectively monitor filtration, 

de-watering or compression system performance necessary for the 

end use of the treated LFG. 

Owners/operators would also need to develop a site-specific 

treatment system monitoring plan that would not only accommodate 

site-specific and end-use specific treatment requirements for 

different energy recovery technologies, but would also ensure 

environmental protection. Preparing the monitoring plan would 

document procedures that landfills are likely already following 

to ensure that the LFG has been adequately treated for its 

intended use. 
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The plan would be required to include monitoring parameters 

addressing all three elements of treatment (filtration, dewatering, and compression) to ensure the treatment system is 

operating properly for the intended end use of the treated LFG. 

The plan would be required to include monitoring methods, 

frequencies and operating ranges for each monitored operating 

parameter based on manufacturer’s recommendations or engineering 

analysis for the intended end use of the treated LFG. 

Documentation of the monitoring methods and ranges, along with 

justification for their use, would need to be included in the 

site-specific monitoring plan. In the plan, the owner/operator 

would also need to identify who is responsible (by job title) 

for data collection, explain the processes and methods used to 

collect the necessary data, and describe the procedures and 

methods that are used for quality assurance, maintenance, and 

repair of all continuous monitoring systems. 

The owner or operator would be required to revise the 

monitoring plan to reflect changes in processes, monitoring 

instrumentation and quality assurance procedures; or to improve 

procedures for the maintenance and repair of monitoring systems 

to reduce the frequency of monitoring equipment downtime. The 

EPA requests input on the definition of treatment system and the 

creation of site-specific treatment system monitoring plans. 
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4. Monitoring and Reporting Flexibility 

Regulatory agencies and landfill owners and operators have 

expressed concerns about the burden and response time of 

agencies responsible for reviewing and approving design plans, 

Alternative Compliance Timeline (ACT) requests, alternative 

remedies and higher operating value (HOV) requests. 

One way to minimize the need for such reviews would be to 

provide more flexibility in wellhead monitoring provisions, as 

described in section IV.D.1 of this notice.

The EPA also solicits input on other ways to streamline the 

monitoring, reporting and notification provisions as part of its 

review of the emission guidelines. For example, currently the 

subparts Cc and WWW of 40 CFR part 60 require site-specific 

design plan review and approval procedures, recognizing the 

unique site-specific topography, climate and other factors 

affecting the design of a GCCS. However, the EPA solicits input

on ways to streamline the design plan submission and approval 

procedures as part of its review of the emissions guidelines. 

Examples of streamlining may include the potential development 

of a process by which approved alternative operating parameters 

could be automatically linked to updates of design plans or 

development of a process by which alternative operating 
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parameters and updated design plans could be approved on a 

similar schedule.

The EPA is also seeking input on the possibility of 

establishing a third-party design plan certification program. 

The third-party program would supplement or replace the current 

approach of requiring the EPA or state review and approval of 

site-specific design plans and plan revisions with a program by 

which independent third parties would review the design plans, 

determine whether they conform to applicable regulatory 

criteria, and report their findings to the approved state 

programs or the EPA (for states without approved programs). The 

program would be designed to ensure that the third-party 

reviewers are competent, independent, and accredited, apply 

clear and objective criteria to their design plan reviews, and 

report appropriate information to regulators. Additionally, 

there would need to be mechanisms to ensure regular and 

effective oversight of third-party reviewers by the EPA and/or 

states that may include public disclosure of information 

concerning the third parties and their performance and 

determinations. Utilizing a third-party certification program 

could help to standardize and expedite design plan reviews, and 

reduce the burden on state regulators. The EPA is considering a 

broad range of possible design features for such a program. Such 
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features include those discussed or included in several 

articles,96,97,98 rules99,100,101 and programs.102,103

We are considering the possibility of requiring sources to 

make design plans (including revisions) available online and 

easily accessible to the public as well as any impediment to 

doing so. We are also seeking input on what constitutes a 

reasonable time period for sources to make the design plans 

available online.

In addition to electronic storage of design plans, the EPA 

also plans to include electronic reporting in athe forthcoming 

proposal amendingthat could amend subparts Cc and WWW of 40 CFR 

part 60 as a result of this review. 

E. Alternative Emission Threshold Determination Techniques

 

96 McAllister, Lesley K., Third-Party Programs to Assess Regulatory 

Compliance, Presented at the Administrative Conference of the United States, 

October 22, 2012.

97 Esther Duflo, et al., Truth-Telling By Third-Party Auditors and the 

Response of Polluting Firms: Experimental Evidence From India, 128 Quarterly 

Journal of Economics 4 at 1499-1545 (2013). 98 First Annual Oversight Report of the Decentralized Gateway Vehicle 

Inspection Program, Missouri Department of Natural Resources and the Missouri 

State Highway Patrol, 2008. 

http://www.dnr.mo.gov/gatewayvip/docs/enforcementrpt.pdf. 99 Renewable Fuel Standard program. 

http://www.epa.gov/OTAQ/fuels/renewablefuels/. 100 Wood Heater Compliance Monitoring Program. 

http://www.epa.gov/compliance/monitoring/programs/caa/woodheaters.html. 101 Mandatory Greenhouse Gas Emissions Reporting, California Environmental 

Protection Agency. http://www.arb.ca.gov/cc/reporting/ghg-rep/ghg-rep.htm. 102 Massachusetts Department of Environmental Protection, Third-Party 

Underground Storage Tank Inspection Program. 

http://www.mass.gov/eea/agencies/massdep/toxics/ust/third-party-ustinspection-program.html
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The EPA is considering adjusting the emission threshold 

determinations that dictate when a GCCS must be installed, 

including variations in the modeling parameters as well as 

adding site-specific emission threshold determination. These 

alternatives may provide additional reporting and compliance 

flexibilities for owners and operators of affected landfills, 

including those that use new technologies to increase oxidation 

of emissions, employ BMPs to increase the effectiveness of GCCS, 

or increase organics diversion and source separation practices.

1. Modeling Adjustments

An affected landfill currently has three different options 

(tiers) for estimating whether the landfill exceeds the NMOC 

emission threshold of 50 Mg per year. The simplest of these, the 

Tier 1 calculation method, uses default values for the potential 

methane generation capacity (L0) and methane generation rate (k) 

to determine when the landfill exceeds the 50 Mg NMOC per year 

emission threshold. The default L0 is 170 m3 per Mg of waste 

(equal to 5,458 cubic feet methane per ton of waste) and the k 

values are 0.05 per year for areas receiving 25 inches or more 

of rainfall per year and 0.02 per year for areas receiving less 

than 25 inches of rainfall. The Tier 1 default NMOC 

 103 Massachusetts Licensed Hazardous Waste Site Cleanup Professional Program, 

http://www.mass.gov/eea/agencies/massdep/cleanup/licensed-site-
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concentration is 4,000 parts per million by volume (ppmv) as 

hexane. If the Tier 1 calculated NMOC exceeds 50 Mg per year, 

the landfill must install controls or demonstrate, using more 

complex Tier 2 or 3 procedures, that NMOC emissions are less 

than 50 Mg per year.

A revised rule could allow for alternative Tier 1 default 

values and modeling techniques based on the amount of organics 

in the waste. For example, the L0 is a function of the moisture 

content and organic content of the waste and L0 decreases as the 

amount of organic matter decreases. Recent studies have shown 

that average U.S. landfill L0 values have decreased 22 percent 

between 1990 and 2012 (from 102.6 m3 per Mg of waste to 79.8 m3

per Mg of waste) due to increased recovery of organic 

materials.104

Subpart HH of the GHGRP also provides separate k-values for 

different types of materials, which could be used as alternate 

Tier 1 default values in revised emission guidelines. Sewage 

A revised rule could allow for landfill-specific L0 

values to be calculated based on the amount of degradable 

organic carbon (DOC), similar to components of Equation HH-1 in 

the GHGRP for MSW landfills (40 CFR part 98, subpart HH).

 professionals.html. 104 Stege, Alex. The Effects of Organic Waste Diversion on LFG Generation and 

Recovery from U.S. Landfills. SWANA’s 37th Annual Landfill Gas Symposium. 

2014. 
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sludge and food waste have the highest k values, followed by 

garden waste, diapers, paper, textiles and wood and straw.11

The IPCC model employs a modeling method to accommodate 

separate k and DOC modeling parameters as well as separate 

calculations for six different categories of organic wastes.105

If the EPA pursues incorporating alternative Tier 1 

modeling values in any revised emission guidelines, the EPA 

would also need to allow for an alternative first-order decay 

model structure to compute a total methane generation rate for 

the landfill based on the sum of the methane generated from each 

separate waste stream. This alternative model may incorporate 

material-specific k and L0 values, instead of a single pair of k 

and L0 values applied to bulk MSW. The EPA requests input on 

whether the alternative modeling parameters and model structure 

in subpart HH of 40 CFR part 98, or other default parameters or 

modeling procedures would be appropriate to use for emission 

threshold determinations in revised emission guidelines. 

The EPA also requests input on whether such an alternative 

modeling procedure would be limited to only those landfills that 

are employing organic diversion or source separation.

2. Site-specific Measurements
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As indicated above, under the current emission guidelines, 

there are three different tiers available to an affected 

landfill to estimate whether the landfill exceeds the NMOC 

emission threshold of 50 Mg/yr. If an affected landfill fails a 

Tier 2 test (i.e., the calculated NMOC emissions are greater 

than 50 Mg/yr), then the landfill must conduct Tier 3 testing or 

install and operate an active GCCS.

The EPA received input recommending the addition of a new 

Tier 4 surface emission monitoring (SEM) demonstration to allow 

increased flexibility for landfills that exceed modeled NMOC 

emission rates if they can demonstrate that site-specific 

methane emissions are actually low. This SEM demonstration would 

be conducted using procedures similar to those currently in 40 

CFR part 60, subpart WWW (see 40 CFR 60.755(d)). If the 

monitoring finds that methane emissions are below a level that 

the EPA adopts in the revised emission guidelines, then 

installation of a GCCS could be delayed. 

As an example, the California Air Resources Board (ARB) 

adopted the Methane Emissions from MSW Landfills regulation in 

 105 Intergovernmental Panel on Climate Change (IPCC), IPCC Guidelines for 

National Greenhouse Gas Inventories. Volume 5 (Waste), Chapter 3 (Solid Waste 

Disposal). 2006.
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2009.106 Under this rule, if a landfill exceeds the waste-inplace and heat input thresholds, the landfill may conduct an SEM 

demonstration prior to being required to install a GCCS. If the 

measured surface methane emissions exceed 200 ppm, the landfill 

must install a GCCS. This SEM demonstration is similar to the 

Tier 4 option being considered by EPA.

The EPA is soliciting input about this new Tier 4 option or 

other ideas for more flexible emission threshold determination 

“Tiers” and what implementation procedures may be appropriate 

for each determination. As the EPA takes this new Tier 4 option 

under consideration, there are some implementation procedures 

that would need to be established. The EPA requests input on all 

aspects of implementing a new Tier 4 option, including the 

following specific items: (1) Which areas of the landfill would 

be subject to SEM requirements because these areas would no 

longer be limited to areas with GCCS installed; (2) what number 

of exceedances over a specified time period would require GCCS 

installation (40 CFR part 60, subpart WWW specifies a new well 

must be installed at three or more exceedances in a quarter); 

(3) what frequency of SEM demonstration (e.g., quarterly 

monitoring for landfills accepting waste, annual monitoring for 

 

106 California Code of Regulations, title 17, subchapter 10, article 4, 

subarticle 6, section 95463, Methane Emissions from Municipal Solid Waste 
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closed landfills) is appropriate; (4) what exceedance level is 

appropriate for determining if a GCCS must be installed (200 ppm 

or some other level); and (5) whether the Tier 4 option would 

apply to all landfills that could demonstrate surface emissions 

less than the determined exceedance level, regardless of how 

this level was achieved; or, whether this option would be made 

available to only those landfills employing and maintaining 

oxidative cover practices, utilizing biofiltration cells, or 

implementing other established best practices or organics 

diversion programs as discussed later in this section. 

F. Considerations for Implementation at Closed vs. Active 

Landfills

The landfills included as part of this review include 

landfills that have accepted waste since November 8, 1987, and 

that commenced construction, reconstruction or modification 

before [DATE OF PUBLICATION OF PROPOSED 40 CFR PART 60, SUBPART 

XXX RULE IN THE FEDERAL REGISTER]. Table 3 of this notice 

summarizes the closure patterns of the approximately 1,800

landfills potentially affected by 40 CFR part 60, subparts Cc 

and WWW.107

 

Landfills.

107 See Docketed Memorandum “Summary of Landfill Dataset Used in the Cost and 

Emission Reduction Analysis of Landfills Regulations. 2014.”
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Table 3. Age Distribution of Existing Landfills 

When did 

landfill 

stop 

accepting 

waste?

All Landfills

Landfills with Design 

Capacity of 2.5 Million 

Mg or Greater

Number of 

Landfills

Cumulative 

Waste-in-Place 

(tons) in 2014

Number of 

Landfills

Cumulative 

Waste-in-Place 

(tons) in 2014

Before 

1990a 33 84,300,000 10 63,200,000

Between 

1990 and 

1995

335 662,300,000 62 465,500,000

Between 

1995 and 

2000

242 583,300,000 56 429,500,000

Between 

2000 and 

2005

97 402,300,000 29 343,000,000

Between 

2005 and 

2010

82 310,900,000 27 250,500,000

Between 

2010 and 

2013 77 469,800,000 31 408,400,000

N/A. 

Active as 

of 2014b 966 6,695,300,000 739 6,493,000,000

Total 1,832 9,208,200,000 954 8,453,100,000

a But accepted waste after November 8, 1987.

b Excludes model landfills that began operating in 2014 and are expected to be 

subject to the proposed subpart XXX NSPS for MSW Landfills.

The EPA recognizes that existing landfills represent a wide 

range of points in the life cycle of a typical landfill. 

Approximately 39 percent of the existing landfills (707/1,832) 

closed prior to 2005 and those landfills collectively account 

for approximately 19 percent of the total waste disposed through 

2014. Because these wastes were disposed of between 10 and 25 

years ago, the LFG emission rates from these older sites are 
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decreasing and have a significantly smaller contribution to 

emissions from this source category. 

Given the wide range of points within a lifecycle that are 

represented by potentially affected existing landfills, and 

recognizing that some of the affected sites have not disposed of 

waste in over 25 years, the EPA believes that the implementation 

of any adjustments to the current framework or incorporation of 

alternative control frameworks or monitoring requirements may 

affect active landfills differently than inactive landfills. 

Therefore, the EPA requests input on how adjusting the current 

framework, selecting an alternative framework or modifying the 

monitoring requirements should be evaluated in terms of 

practicality, cost and emission reductions as these adjustments 

affect landfills of various ages and activity levels. 

G. Implementation Issues

Since the landfills emission guidelines were promulgated in 

1996, the EPA has become aware of a number of implementation 

issues for which landfill owners and operators, as well as 

regulators, need clarification. This section presents those 

issues and requests input on those clarifications and potential 

resolutions. 

1. LFG Treatment
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In this notice, the EPA is soliciting input on what 

constitutes sufficient LFG treatment. In the Federal Register

notice proposing a new subpart resulting from its review of the 

landfills NSPS (40 CFR part 60, subpart XXX), the EPA refined a 

numeric definition of LFG treatment and solicited input on a 

non-numeric definition that required compression, dewatering,

and filtration of LFG, as well as the creation of a sitespecific monitoring plan. The EPA requests input on whether a 

non-numeric or numeric treatment requirement is appropriate for 

landfills subject to the emission guidelines. Further, the EPA 

requests input on whether previously proposed definitions of LFG

treatment should be adopted or if other approaches to LFG

treatment should be explored. We are also requesting input on 

expanding the use of treated LFG fuel for a stationary 

combustion device, as some people have previously interpreted 

this compliance option, but also include other uses such as the 

production of vehicle fuel, production of high-Btu gas for 

pipeline injection, or use as a raw material in a chemical 

manufacturing process.

2. Closed Areas 

To determine whether NMOC emissions from nonproductive 

areas of a landfill are less than 1 percent of the total 

landfill NMOC emissions (and hence controls are not required), 
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the landfills regulations (40 CFR part 60, subparts Cc and WWW) 

rely on modeled NMOC rates. To refine the measurements of these 

nonproductive areas, the EPA is requesting input on allowing 

landfill owners or operators to use either the measured or

modeled flow of LFG to determine if an area is nonproductive. 

The EPA is also requesting input on what criteria and procedures 

would be considered acceptable for making these estimates. The 

provisions would apply to physically separated, closed areas of 

landfills.

3. Submitting Corrective Action Timeline Requests

If a landfill exceeds a wellhead operating parameter, the 

landfill owner or operator must initiate corrective action 

within 5 days and follow the timeline in 40 CFR part 60, subpart 

WWW for correcting the exceedance. During implementation of 

subpart WWW, the question has been raised whether a landfill 

needs agency approval of corrective action timelines that exceed 

15 calendar days but are less than the 120 days allowed for 

installing a GCCS.

The EPA is seeking input on whether a specific schedule for 

submitting these requests for alternative corrective action 

timelines is appropriate because investigating and determining 

the appropriate corrective action, as well as the schedule for 

implementing the corrective action, will be site specific and 
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depend on the reason for the exceedance. We also solicit input

on whether any clarifications should be included in the revised 

emission guidelines to expedite the submission of any 

alternative time line requests (i.e., as soon as they know that 

they would not be able to correct the exceedance in 15 days or 

expand the system in 120 days) to avoid being in violation of 

the rule.

To address implementation concerns associated with the time 

allowed for corrective action, the EPA requests input on an 

approach that extends the requirement for notification from 15 

days to as soon as practicable, but no later than 60 days. Many 

requests for an alternative compliance timeline express the need 

for additional time to make necessary repairs to a well that 

requires significant construction activities. Extending the time 

period to as soon as practicable but no later than 60 days may 

reduce the burden and ensure sufficient time for correction. If 

the EPA were to extend the time period, then the EPA also would

consider removing the requirement to submit an alternative 

timeline for correcting the exceedance. Thus, by no later than 

day 60, the landfill would have to either have completed the 

adjustments and repairs necessary to correct the exceedance, or 

be prepared to have the system expansion completed by day 120.

The EPA is also requesting input on whether 60 days is the 
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appropriate amount of time that would allow owners or operators 

to make the necessary a repairs.

V. Statutory and Executive Order Reviews

Under Executive Order 12866, titled Regulatory Planning and 

Review (58 FR 51735, October 4, 1993), this is a “significant 

regulatory action” because the action raises novel legal or 

policy issues. Accordingly, the EPA submitted this action to the 

Office of Management and Budget (OMB) for review under Executive 

Order 12866 and any changes made in response to OMB 

recommendations have been documented in the docket for this 

action. Because this action does not propose or impose any 

requirements, other statutory and Executive Order reviews that 

apply to rulemaking do not apply. Should the EPA subsequently 

determine to pursue a rulemaking, the EPA will address the 

statues and Executive Orders as applicable to that rulemaking. 

Nevertheless, the EPA welcomes input and/or information 

that would help the EPA to assess any of the following: The 

potential impact of a rule on small entities pursuant to the 

Regulatory Flexibility Act (RFA) (5 U.S.C. 601 et seq.); 

potential impacts on federal, state, or local governments 

pursuant to the Unfunded Mandates Reform Act ((UMRA) (2 U.S.C. 

1531-1538); federalism implications pursuant to Executive Order 

13132, titled Federalism (64 FR 43255, November 2, 1999); 
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availability of voluntary consensus standards pursuant to 

section 12(d) of the National Technology Transfer and 

Advancement Act of 1995 (NTTAA), Public Law 104-113; tribal 

implications pursuant to Executive Order 13175, titled 

Consultation and Coordination with Indian Tribal Governments (65 

FR 67249, November 6, 2000); environmental health or safety 

effects on children pursuant to Executive Order 13045, titled 

Protection of Children from Environmental Health Risks and 

Safety Risks (62 FR 19885, April 23, 1997); energy effects 

pursuant to Executive Order 13211, titled Actions Concerning 

Regulations that Significantly Affect Energy Supply, 

Distribution, or Use (66 FR 28355, May 22,2001); paperwork 

burdens pursuant to the Paperwork Reduction Act (PRA) (44 U.S.C. 

§3501); or human health or environmental effects on minority or 

low-income populations pursuant to Executive Order 12898, titled 

Federal Actions to Address Environmental Justice in Minority 

Populations and Low-Income Populations (59 FR 7629, February 16, 

1994). The EPA will consider such comments during the 

development of any subsequent rulemaking.
Emission Guidelines and Compliance Times for 

Municipal Solid Waste Landfills

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List of Subjects in 40 CFR Part 60

Environmental protection, Administrative practice and 

procedure, Air pollution control, Reporting and recordkeeping 

requirements.

.

Dated:

Gina McCarthy, 

Administrator.