Landfill Activities

This page last reviewed April 24, 2017


The landfilling of organic materials leads to the anaerobic breakdown of these materials into landfill gas. Landfill gas is primarily composed of methane and, to a lesser but significant amount, volatile organic compounds (VOC). These gases are released from the landfill as fugitive emissions. Methane is a potent greenhouse gas, which is 28-36 times more potent than CO2 as a global warming gas. VOCs react with NOx emissions to form ground-level ozone. NOx is a common combustion product: flares, boilers, internal combustion engines, and other combustion processes typically generate NOx emissions. ARB, in partnership with local, State and federal entities is working to address methane and related emissions through implementation of various programs such as the Landfill Methane Rule (discussed below), Proposed Short-Lived Climate Pollutant Strategy, and in the 2030 Target Scoping Plan Discussion Draft.

Environmental Justice Advisory Committee (EJAC) Considerations:

ARB also partners with its EJAC to ensure implementation of its climate change programs provide tangible benefits, and do not negatively impact disadvantaged communities (DACs). To assist ARB’s efforts, the EJAC has provided recommendations that will guide our efforts as we design and implement strategies to reduce climate change and health impacts from industrial, commercial, agricultural and transportation sources. More information regarding the EJAC and its recommendations, many of which are related to landfills and organics, can be found here:

U.S. EPA's Updated Rules to Regulate Municipal Solid Waste Landfills:

History and Background:

On March 12, 1996, the United States Environmental Protection Agency (U.S. EPA) promulgated a regulation requiring emission controls for large municipal solid waste (MSW) landfills (61 Fed. Reg. 9905). The regulation is entitled “Standards of Performance for Stationary Sources and Guidelines for Control of Existing Sources: MSW Landfills.” It includes both New Source Performance Standards (NSPS) that regulate emissions from new landfills and Emission Guidelines that regulate emissions from existing landfills. See the U.S. EPA webpage ( for more information.


The NSPS was implemented by the districts, who have primary authority to regulate stationary sources such as landfills in California. For existing landfills, the regulation required each state to submit a plan to U.S. EPA which identified how the State intended to meet the federal requirements contained in these guidelines. California air districts with affected landfills (in conjunction with ARB) adopted rules to implement the Emission Guidelines. These rules were forwarded to ARB and compiled for inclusion in the State plan. In September 1997, California submitted a State Plan to implement the guidelines.

2016 Updates to the Federal Landfill Rules:

On August 29, 2016, U.S. EPA finalized a new subpart under section 111(b) of the Clean Air Act for new, modified and reconstructed municipal solid waste landfills under 40 CFR Part 60, Subpart XXX (81 FR 59332) effective October 28, 2016. These New Source Performance Standards apply to landfills that commenced construction, reconstruction or modification after July 17, 2014. The districts will continue to implement the new NSPS provisions under their stationary source authority. The existing NSPS (40 CFR part WWW) for MSWs remains in effect.

Emission Guidelines
In a separate, but related action, U.S. EPA also issued updated emission guidelines for reducing emissions from existing MSW landfills under 111(d) of the Clean Air Act. The “Emission Guidelines and Compliance Timelines for Municipal Solid Waste Landfills” (Emission Guidelines) (81 FR 59275) (40 CFR Part 60, Subpart Cf), is also effective October 28, 2016. A link to U.S. EPA's NSPS and Emissions Guidelines, as well as the EPA database of the existing MSW landfills can be found below:

ARB's Responsibilities in Response to the Updated Emissions Guidelines

As before, the Emission Guidelines require each state to submit a compliance plan to U.S. EPA, which is due by May 30, 2017. ARB is currently working with the California Air Pollution Control Officers Association (CAPCOA) and local air districts to develop its 2017 compliance plan. These newly updated federal rules complement ARB's Landfill Methane Rule, help the State meet its climate change goals, and ensure emissions from this source category do not adversely affect public health.

California State Plan for Compliance with U.S. EPA's Emissions Guidelines:
Meetings and Documents

Landfill Methane Control Measure:

wellhead The Air Resources Board (ARB) approved a landfill regulation which became effective June 17, 2010 that reduces emissions of methane, a greenhouse gas, from municipal solid waste (MSW) landfills. The regulation is a discrete early action greenhouse gas emission reduction measure, as described in the California Global Warming Solutions Act (“AB 32”). The regulation primarily requires owners and operators of certain uncontrolled MSW landfills to install gas collection and control systems, and requires existing and newly installed gas and control systems to operate in an optimal manner. The regulation allows local air districts to voluntarily enter into memoranda of understanding (MOU) with ARB to implement and enforce the regulation and to assess fees to cover costs. This webpage follows the development, implementation and enforcement of the control measure.

  • Landfill Methane Control Measure Regulatory Activities 
  • Landfill Gas Tool
    • ARB staff has developed a Landfill Gas Tool to assist owners and operators in complying with the landfill regulation. The tool is based on the mathematically exact first-order decay model from the 2006 IPCC guidelines and is designed to estimate the fugitive emissions from a landfill that does not have a landfill gas collection system. It uses the Second Assessment Report (SAR) Global Warming Potential (GWP) of 21 for methane. It also includes an estimate of the landfill’s captured gas heating value (in MMBtu/hr).  If you have comments or questions about this tool please contact Larry Hunsaker, Staff Air Pollution Specialist.
      Landfill Emissions Tool Version 1.3 [Excel-523 KB]

For questions, please contact:
Renaldo Crooks at (916) 327-5618