Enforcement Alert: EPA Finds MSW Landfills are Violating Monitoring and Maintenance Requirements

EPA Investigations Find Municipal Solid Waste Landfill Operators are Failing to Properly Conduct Compliant Monitoring and Maintenance of Gas Collection and Control System

This Enforcement Alert is intended to remind municipal solid waste (MSW) landfill operators and owners, and their consultants, of their obligation to conduct proper monitoring techniques and system maintenance to ensure compliance with the Clean Air Act’s MSW landfill requirements.

 The U.S. Environmental Protection Agency (EPA) has found recurring Clean Air Act compliance issues at MSW landfills leading to the significant release of methane, a climate super-pollutant, and other air pollutants. MSW landfills are the third largest source of methane emissions in the United States, and more than 100 inspections over the past three years reveal that that many operators are not complying with the Clean Air Act’s applicable regulatory requirements. 

Compliance issues include: 

  • Improper monitoring resulting in excess surface emissions of methane,  

  • Failure to properly design, install, operate, and maintain the gas collection and control system (also referred to as the “GCCS”), and  

  • Failure to maintain adequate MSW landfill cover integrity. 

Reducing methane emissions from MSW landfills is an integral part of the EPA’s Mitigating Climate Change National Enforcement and Compliance Initiative. In this effort, the EPA is concentrating its compliance monitoring efforts on significant sources of air emissions at MSW landfills and employing civil and criminal enforcement resources where needed. In addition to addressing climate concerns, ensuring compliance at MSW landfills will achieve emission reductions that benefit downwind communities. 

MSW landfill gas is comprised of roughly 50% carbon dioxide and 50% methane gases by volume. Methane is a greenhouse gas that is 28 times more potent than carbon dioxide in trapping heat in the atmosphere. It is also flammable and explosive if not properly managed. Other trace gaseous constituents include non-methane organic compounds (also referred to as “NMOC”), which include volatile organic compounds (VOCs) and hazardous air pollutants (HAPs), as well as sulfur-based compounds, all of which can contribute to air quality issues and public health concerns.

Methane and VOCs contribute to ground-level ozone formation, and VOC emissions are a precursor to fine particulate matter formation. Ground-level ozone, particulate matter, sulfur gases, and HAP emissions are associated with premature mortality, respiratory distress, irritation, asthma, nausea, and cancer, among other issues. NMOC and sulfur gases contribute to odors and quality of life issues for surrounding communities. 

The EPA is issuing two enforcement alerts on MSW landfills at the same time. The other alert addresses violations of the emission reporting requirements that result in landfills improperly avoiding control requirements. Enforcement Alert: EPA Finds MSW Landfills are Violating Landfill Gas Emission Rate Calculation Requirements is available on the Agency’s website.

On this page:

I. Regulation of MSW Landfills

MSW landfills are regulated under several environmental laws and regulatory programs. This Enforcement Alert focuses on MSW landfills that may be subject to a combination of the following standards under the Clean Air Act:  

Under these regulations, MSW landfills with a reported NMOC emission rate of above 34 megagrams per year must install and operate a well-designed GCCS to control landfill gas emissions. The purpose of a GCCS is to capture and control the gas generated in the MSW landfill. 

Under the Clean Air Act, MSW landfills subject to control requirements are required to conduct quarterly surface emissions monitoring (also referred to as “SEM”) to ensure methane emissions are below 500 parts per million (ppm) above background concentrations and to determine if the GCCS is adequately collecting gas from all areas of the MSW landfill. In addition, monthly wellhead monitoring is required for temperature, oxygen (or nitrogen), and wellhead pressure (vacuum) to ensure the GCCS is operating properly and collecting gas at a sufficient rate.  

II. Findings from EPA Inspection at Municipal Solid Waste Landfills 

More than 100 EPA inspections over the past three years reveal that many MSW landfill operators are not complying with applicable regulatory requirements, including GCCS requirements, SEM procedures, and maintaining cover surface integrity.  

A.  Surface Emission Monitoring Procedures 

Exposed waste creates paths for surface emissions.

In numerous field inspections, the EPA observed that many MSW landfill operators, and their contractors, are failing to comply with the SEM requirements at 40 C.F.R. §§ 63.1958(d) and 63.1960(c)-(d), including properly following Method 21. MSW landfills operators are required to use Method 21 to determine compliance with the surface methane standard. Recent inspections also revealed widespread shortcomings in the SEM program at MSW landfills, including methane emissions at higher rates of exceedance, with many above 50,000 ppm, which is 100 times higher than the regulatory limit.

Clean Air Act regulations require MSW landfill operators to follow the proper monitoring procedures for SEM, as follows: 

  • Monitoring speed: In order to get the most accurate Method 21 readings, the SEM should be conducted while walking at a slow pace. If the pace on the serpentine path is too fast, the equipment will not have adequate time to identify an elevated concentration. The regulations require that the technician must pause and seek the emission source when readings rise, potentially backtracking to account for delayed readings due to instrument response time. Monitoring from ATVs or 4x4 vehicles cannot produce accurate readings. Drone-based SEM may only be conducted if following the requirements of Other Test Method (OTM) 51.  

  • Monitoring time: When elevated readings are observed, Method 21 – 8.3.1 requires technicians to slowly sample until the maximum reading is obtained and then leave the probe at this location for twice the instrument response time.  

  • Departure from established path: The technician should depart from the established path as frequently as necessary to monitor areas of potential emissions. These areas include, but are not limited to dead, distressed, or missing vegetation; seeps, ruts or gullies; cracks and holes; penetrations, including gas extraction wells and any other object ultimately passing through the landfill cover, including exposed waste. See figure 1. Per Method 21 – 8.3.1, sampling should go fully around each penetration. There may be multiple penetrations at wellheads.  

  • Expired calibration gas: The technician should ensure that the equipment is calibrated according to the requirements of Method 21 and that the gases used for calibration are not expired.  

  • Excluded areas from monitoring: While the regulations allow MSW landfills to exclude certain areas from the SEM (e.g., areas with steep slopes or other dangerous areas), the EPA observed during recent inspections that areas that are not dangerous are improperly excluded from monitoring. If a MSW landfill excludes areas from the SEM, the facility should document and explain the basis for excluding each area from monitoring in the surface emission design plan and SEM reports. The regular side slopes of the landfill may not be excluded from monitoring per the regulations.

B.  Gas Collection and Control System: Design, Installation, Operations and Maintenance Considerations

A properly designed, installed, operated, and maintained GCCS greatly reduces the amount of landfill gas emissions. 

Design: The regulations require the GCCS design to cover all areas where waste has been in place for five years (or two years if at final grade), accommodate the expected maximum landfill gas generation as calculated under the regulations, and ensure the well radiuses of influence fully cover all subject waste. The regulations require a design plan prepared by a professional engineer. The initial GCCS design should be re-evaluated after analyzing operational data to assess the system performance. Design plans should ensure sufficient density of gas collection at all stages of MSW landfill and GCCS build-out.   

Installation: Clean Air Act regulations require landfill owner/operators to use proven techniques during GCCS construction to ensure a well-built system that follows the required design specifications. (40 C.F.R. § 63.1962)  

Construction oversight is important to identify potential changes in the system design needed to accommodate site conditions. Owner/operators should ensure that “as-built” drawings are maintained to document any changes from the GCCS design plan and provide MSW landfill operators with a reference point to help pinpoint the location of components in the future to address maintenance issues or expansion of the system.  

Owner/operators should include changes from the design plan in revised design plans submitted to EPA or its delegate for approval. (40 C.F.R. § 63.1981(e))  

Operation & Maintenance: Periodic evaluation of the GCCS will help MSW landfill owners and operators identify areas in need of adjustment or repair. This will optimize the performance of the system and reduce downtime. Clean Air Act regulations require monitoring on a monthly basis of wellhead data. The MSW landfill operator should evaluate these and other data for trends that may indicate a GCCS compliance issue.

Figure 2: Poorly maintained vertical LFG well with cracked hose resulting in emission leaks and introducing oxygen into the GCCS.

Common GCCS issues to watch for include liquid levels at each well (e.g., watered-in wells), subsurface well damage resulting from waste settling, header pipe damage, wellhead damage such as damaged pipes and hoses, and bad seals. See Figure 2. These components should be visually inspected and repaired as needed to ensure the GCCS is operating as originally designed.

As new lifts of waste are deposited and wells are raised, operators should ensure adequate perforation in the wells or install additional collectors to ensure landfill gas collection in the upper levels of waste.  

C.  MSW Landfill Cover Integrity

MSW landfill regulations require owners and operators to inspect the landfill cover monthly to identify and repair any cover integrity issues. A well-maintained MSW landfill cover plays a critical part by retaining gas within the MSW landfill, preventing air intrusion into the landfill (and thus avoiding sub-surface oxidation events), and preventing excessive liquid infiltration into the landfill which can cause flooded wells and create difficulty in managing leachate. The EPA observed during inspections that cover integrity issues such as exposed waste, leachate breakouts, and erosion gullies continue to be a widespread problem. Additionally, the EPA has found that many landfills do not have rigorous programs to identify and correct cover integrity problems.

III. Overview of Recent Enforcement Cases

Case examples include: 

  • Riverbend Landfill – McMinnville, OR (2021): For failing to conduct compliant SEM, ensure proper MSW landfill cover integrity, and monitor all gas wells monthly, Riverbend Landfill agreed in a settlement with the EPA to correct these Clean Air Act violations, pay a penalty, and follow improved monitoring standard operating procedures. 

  • City of Midland Landfill – Midland, MI (2020): The City of Midland Landfill failed to (1) submit semi-annual reports of GCCS operations and SEM; (2) meet the surface methane standard; (3) perform monthly cover integrity inspections; and (4) contain and control gas migration from the MSW landfill. As part of a settlement agreement to resolve these Clean Air Act violations, the city committed to a revised SEM plan and the installation of new gas extraction wells with accompanying reports documenting their operation.  

  • Gary Sanitary Landfill – Gary, IN (2020): The City of Gary failed to adequately design and properly operate, monitor, and maintain the gas collection and control system as required by the Clean Air Act. The city agreed in a settlement with EPA to pay a penalty and undertake the following corrective actions: (1) follow specific procedures to monitor active and passive gas wells for pressure, gas temperature, and oxygen levels; (2) follow SEM procedures and keep methane emissions below 500 ppm; (3) report and mitigate any methane exceedances; (4) maintain adequate cover integrity; and (5) monitor gas probes to prevent gas migration.

IV.  Resources

Helpful resources to assist owners and operators with information to achieve compliance are available on the following EPA web pages and sites:  

Disclaimer:  This Enforcement Alert addresses select provision of EPA regulatory requirements using plain language.  Nothing in this Enforcement Alert is meant to replace or revise any Clean Air Act permit, any EPA regulatory provision, or any other part of the Code of Federal Regulations, the Federal Register, or the Clean Air Act.

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Last updated on September 25, 2024