Landfill Air Quality Rules

U.S. Environmental Protection Agency (USEPA) has regulations that affect air emissions from municipal solid waste landfills (MSWLF). A municipal solid waste landfill is a site that receives household waste and may also receive nonhazardous solid wastes and very small quantity generators (VSQG). MSWLFs emit landfill gas (LFG) generated from the biodegradation of organic materials. The focus of most of the rules are LFG air pollutants such as nonmethane organic compounds (NMOCs) and hazardous air pollutants (HAPs). Currently, regulations regarding MSWLF methane emissions pertain to safety issues and reporting of emissions.

For more information on landfills and methane, go to Cimarron’s blog:

Below is a summary of federal regulations affecting MSWLFs.


New Source Performance Standards – Nonmethane organic compounds emissions

USEPA New Source Performance Standards (NSPS) are federal technology-based standards for criteria air pollutants emitted by “new” facilities. “New” facilities are facilities that were constructed, reconstructed, or modified after the proposal date of the NSPS standard. NSPSs set minimum control requirements known as best demonstrated technology. NSPS regulations are typically administered by the State environmental permitting agency.

These rules regulate emissions of nonmethane organic compounds (NMOC).

The NSPSs that affect municipal solid waste landfills (MSWL) include the following:

  • 40 CFR 60 Subpart WWW – Standards of Performance for Municipal Solid Waste Landfills That Commenced Construction, Reconstruction, or Modification on or After May 30, 1991, but Before July 18, 2014.
  • 40 CFR 60 Subpart XXX – Standards of Performance for Municipal Solid Waste Landfills That Commenced Construction, Reconstruction, or Modification After July 17, 2014.

Generally, these rules require control of NMOC emissions. Emission controls are required if the NMOC emission rate is equal to or greater than 34 megagrams per year (37.5 tons/yr). Methods for calculating NMOC emission rate specified in the rules.

The rule lists the following emission options:

  1. Non-enclosed flare designed and operated according to the requirements of 40 CFR 60.18
  2. Enclosed combustion device (ECD) with a 98% NMOC destruction efficiency or an outlet concentration of 20 ppm NMOC by volume or less
  3. A gas treatment system that processes the collected gas for subsequent sale or beneficial use such as Renewable Natural Gas (RNG). 


Emission Guidelines (EG) for MSWL – State Rules

USEPA Emission Guidelines (EG) are used to guide States to create NSPS-like rules for existing facilities not covered by a NSPS regulation. EG regulations cover existing MSWL facilities not constructed, reconstructed or modified on or after the effective date of the corresponding NSPS. EG regulations are State specific rules that meet federal requirements.

Rules in 40 CFR 60 Subpart OOO – Federal Plan Requirements for Municipal Solid Waste Landfills That Commenced Construction On or Before July 17, 2014 and Have Not Been Modified or Reconstructed Since July 17, 2014 are the guidance for State MWLF rules. These rules, as implemented by the States, regulate emissions of nonmethane organic compounds (NMOC).

Each State implements rules that follow the guidelines in OOO EG.


40 CFR 63 Subpart AAAA – National Emission Standards for Hazardous Air Pollutants: Municipal Solid Waste Landfills

National Emission Standards for Hazardous Air Pollutants (NESHAPs) are rules regulating hazardous air pollutants (HAPs) from all emission sources. The rules set standards for major sources and area sources of HAPs. A HAP major source has the potential to emit 10 tons per year (tpy) of any one HAP or 25 tpy of any combination of HAPs. Area sources of HAPs are defined as any source that is not a major source. Standards are in effect for existing and new facilities based on the dates specified in the rules.

The rule affects MSWLs that are major sources of HAPs and MSWLs with greater than 2.5 million megagrams (Mg) and 2.5 million cubic meters capacity that have uncontrolled emissions greater than 50 Mg/year of nonmethane organic compounds (NMOC). Affected facilities must install and operate a gas collection and control system. The rule has overlapping requirements with NSPS XXX.

Approximately 738 MSW MSWLs are subject to the NESHAP rules.

The primary HAPs emitted by MSWLs include:

  • Vinyl chloride
  • Benzene
  • Ethyl benzene
  • Toluene
  • Xylenes

The rule specifies methods for calculating nonmethane organic compounds (NMOC) mass emission rates and control efficiency.

MSWLs with NMOC emissions equal to or greater than 50 megagrams per year were required to comply with the new requirements in NESHAP AAAA beginning no later than September 27, 2021. Requires a collection system to control landfill gas NMOC emissions. Controls can be:

  • Open-tipped flare
  • Enclosed combustion device (ECD) that reduces NMOC by at least 98 weight percent or reduces outlet NMOC concentration to less than 20 ppmv, dry basis as hexane at 3-percent oxygen.

The facility also must implement a Startup, Shutdown and Malfunctions (SSM) plan.


NSPS JJJJ Internal Combustion Engines Used at MSWL

NSPS 40 CFR 60 Subpart JJJJ – Standards of Performance for Stationary Spark Ignition Internal Combustion Engines applies to new engines operating at facilities. This NSPS rule has specific requirements for spark ignition internal combustion engines using landfills/digester gas applications.

Landfill gas is defined as, a gaseous by-product of the land application of municipal refuse typically formed through the anaerobic decomposition of waste materials and composed principally of methane and CO2.

NSPS JJJJ, Table 1 of the rule has engine NOx, CO and VOC emission limits that are less stringent than other engines burning natural gas.


GHG Reporting Rules

The USEPA’s GHG Reporting Rule in 40 CFR 98 Subpart HH requires MSWLs that received waste on or after January 1, 1980, and emit 25,000 metric tons of GHGs to annually report GHG emissions. The primary GHG for MSWLs is methane. Emissions from the combustion of fuels (e.g., landfill gas, natural gas, diesel) by engines would report under 40 CFR 98 Subpart C. Subpart HH reporting requires calculations based on modeled methane generation using measured and estimated historic annual waste disposal quantities, soil oxidation and quantity of methane recovered and destroyed.

In 2020, there were 1,123 MSWLs reporting GHG emissions for a total of 85 million metric tons CO2e. Data on MWLF facilities reporting GHG emissions can be found using the Facility Level Information on Greenhouse Gases (FLIGHT) tool.

Reports are submitted using USEPA’s electronic Greenhouse Gas Reporting Tool (e-GGRT).


EPA Solid Waste Regulations – Methane

Federal rules in 40 CFR 258 – Criteria for Municipal Solid Waste Landfills require gas monitoring to ensure the concentration of methane does not exceed 25% of lower explosion limit (LEL) of methane in facility structures and at the facility’s property boundary. Facilities must take corrective action if methane gas levels exceed the LEL limits.


Air Permitting

MSWLs with a design capacity greater than or equal to 2.5 million metric tons and 2.5 million cubic meters are subject to Title V/Part 70 or Part 71 federal permitting requirements. Part 70 operating permits are administered by the State air permitting agency. Part 71 permits are administered by the USEPA. Most MSWLs would obtain a State administered Title V/Part 70 permit. Title V air permits do not have specific emission controls for facilities or emission sources. Title V permit operating permits are designed to ensure that all Federal and State applicable requirements are listed for the operator and air permitting regulator.


EPA Air Quality Regulation Navigation Tools

The following link is for navigation rules for EPA regulations that apply to landfills.


Summary and Conclusions

Municipal solid waste landfills (MSWLs) emit landfill gas (LFG) that contains methane and nonmethane organic compounds (NMOC). These gases are generated by the decomposition of organic matter. Methane is a greenhouse gas that is targeted for reduction to address climate change. NMOC are air pollutants that are regulated by federal and State air quality rules.

Rules affecting MSWLs include federal EPA rules and State rules based on federal guidance regulations.

Typical control of LFG includes flares and enclosed combustion devices (ECD). Also, LFG can be treated/conditioned to meet renewable natural gas (RNG) standards and used for a beneficial use.


Cimarron – Who We Are

Cimarron’s overall goal is to reduce greenhouse gas emissions for all industries as we work with our clients to create a cleaner environment.

We can assist you in your landfill gas emission control needs.

The company engineers and manufactures environmental, production and process equipment for the upstream, midstream and downstream energy industries, as well as environmental control solutions for biogas at wastewater facilities, digester tanks and landfills.

Cimarron offers our customers the know-how and environmental expertise to meet the environmental standards of today and tomorrow. Cimarron is committed to bring value to the Energy industry and their shareholders based on our financial strength, experienced personnel, and engineering capabilities.

As a company, we thrive every day to make a difference through innovation (e.g. ESG), customer focus, and operational efficiency. In addition to being present in all major regions in the US, Cimarron serves more than 45 countries around the world, ranging from offshore to desert. From key operational centers in the United States, Italy and the United Arab Emirates, Cimarron offers ongoing service and support through its own field service personnel and strategic third-party partners, creating a cleaner environment for our customers and their shareholders.

Since its founding in the mid-1970’s in Oklahoma, the company’s product offering has expanded from production equipment to include the largest line of environmental solutions that capture or incinerate fugitive vapors. With the acquisitions of HY-BON/EDI in 2019 and AEREON (including Jordan Technologies) in 2020, Cimarron has added strong brands, products, and services to its portfolio.

Please contact us to learn more about our products and services and about all our ESG solutions at or visit our website

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