Landfill Activities

This page last reviewed January 23, 2018



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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 72-84 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. CARB, 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), Short-Lived Climate Pollutant Strategy, and in the 2017 Climate Change Scoping Plan Update.

Environmental Justice Advisory Committee (EJAC) Considerations:

CARB also partners with its EJAC to ensure that implementation of its climate change programs provide tangible benefits, and do not negatively impact disadvantaged communities (DACs). To assist CARB’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: /cc/ejac/ejac.htm

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 CARB) adopted rules to implement the Emission Guidelines. These rules were forwarded to CARB and compiled for inclusion in the State plan. In September 1997, California submitted its 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 implement the new NSPS provisions under their stationary source authority. The existing NSPS (40 CFR part WWW) for MSWs remains in effect concurrently with the new NSPS.

Emission Guidelines
In a separate, but related action, U.S. EPA also issued updated emission guidelines for reducing emissions from existing MSW landfills under section 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 Emission Guidelines, as well as the EPA database of the existing MSW landfills can be found below:

CARB's Responsibilities in Response to the Updated Emission Guidelines

As before, the Emission Guidelines require each state to submit a compliance plan to U.S. EPA, which was due by May 30, 2017. On May 25, 2017, the California Air Resources Board (CARB or Board) adopted California’s State Plan (see below) to comply with the updated federal Emissions Guidelines and the plan was subsequently sent to U.S. EPA on May 30, 2017. 

Federal Reconsideration of Emission Guidelines and 90-day Stay

In response to a petition filed by industry, U.S. EPA announced the convening of a proceeding for reconsideration of the final rule.  U.S. EPA indicated as part of the reconsideration it would prepare a notice of proposed rulemaking.  Subsequently on May 31, 2017, U.S. EPA published notice of a 90-day stay of the Guidelines until August 29, 2017. The Federal Register notice of U.S. EPA’s 90-day stay of the Emissions Guidelines is available at

CARB commits to working with U.S. EPA during the stay to ensure the Emission Guidelines remain protective of environmental and public health to the maximum extent feasible.
California State Plan for Compliance with U.S. EPA's Emissions Guidelines:
Meetings and Documents

Landfill Methane Control Measure:

wellhead The California Air Resources Board (CARB) 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 CARB 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
    • CARB 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:
Mei Fong at (916) 324-2570