This article was originally published in the Trends March/April 2026, Volume 57, Number 4 issue from the American Bar Association's Section of Environment, Energy, and Resources.
The management of municipal solid waste (MSW) has come a long way from disposal through open burning or discarding in unlined dumps or waterways. Modern MSW landfills are intentionally designed, highly regulated systems of environmental controls. But operating an MSW landfill comes with unique challenges to maintain protection of public health and the environment. These disposal sites accept a wide variety of municipal waste from households and businesses. As junk goes in, so must junk come out—landfills produce leachate and landfill gas, both of which must be managed in accordance with federal and state regulations. This article provides a brief overview of the current state of regulation and management of landfill gas from MSW landfills.
Landfill gas is generated through the decomposition of organic material in the landfill in the absence of oxygen. The gas is largely compromised of methane (45 to 65 percent), a potent greenhouse gas with a global warming potential roughly 30 times greater than carbon dioxide, and non-methane organic compounds (NMOC), such as volatile organic compounds. To prevent the release of these gases into the atmosphere, landfills install and operate gas collection and control systems (GCCS) that capture and destroy the landfill gas through combustion with flares. In some cases, the landfill gas is put to beneficial use—more on that below. In those cases, the combusted gas is released as carbon dioxide and water vapor.
Since 1996, the Environmental Protection Agency (EPA) has regulated landfill air emissions under the Clean Air Act (CAA), adding MSW landfills as a New Source Performance Standard (NSPS) category, establishing emission standards for new municipal solid waste landfills and emission guidelines for existing MSW landfills.1 This rule was the first requirement for MSW landfills to install GCCS to control emissions. Significant amendments to the NSPS rules occurred in 2016, with the purpose of achieving additional reductions in emissions by lowering the emissions threshold at which a landfill must install a GCCS from 50 metric tons of NMOC per year to 34 metric tons per year. In 2003, MSW landfills became subject to NESHAP; MSW landfills emit as hazardous air pollutants vinyl chloride, ethyl benzene, toluene, and benzene. These two categories of rules create the general regulatory framework for MSW landfills under the CAA.
Some states, such as California, Colorado, Washington, and Oregon, have enacted rules more stringent than the Federal CAA requirements, including by directly regulating methane. Currently, California is conducting a rulemaking to adopt amendments to its Landfill Methane Rule (LMR). The proposed LMR amendments are intended to seize opportunities for deeper emission reductions, for example by leveraging new technologies, such as satellite-based plume detection and advanced monitoring tools, to improve leak detection and repair; tightening standards and repair time lines to ensure prompt mitigation; and adding additional monitoring parameters. Colorado recently adopted revisions to its
methane reduction rule. The adopted rules require actions similar to California’s proposed LMR amendments, such as utilizing tools like satellite imaging and plane sensors to identify large emission sources at landfills, and advanced monitoring tools to improve periodic methane monitoring.
While no landfill gas rulemakings are on EPA’s docket at this time, EPA recently conducted a non-regulatory docket to obtain knowledge on emerging technologies and practices for regulating emissions from MSW landfills, in an effort “to gather input on ways [EPA] can streamline, improve, and harmonize the current suite of emissions regulations that cover these sources.” EPA requested feedback from the regulated community on a series of white papers EPA prepared, which covered topics such as organic waste diversion and reducing lag time for GCCS installation and operation. Non-regulatory dockets help inform regulators of industry specific challenges that an agency may be unaware of and should consider as it works towards a rulemaking.
Methane is not just a pollutant, but when captured, can be utilized as energy. Beneficial use of landfill gas is on the rise as technologies and permitting around these projects is better understood and tested. These projects typically include landfill gas to energy projects that generate electricity through the combustion of landfill gas in internal combustion engines or in boilers. Landfill gas can be cleaned and compressed for use as renewable natural gas. It can also be converted into hydrogen gas, which in turn can be used in hydrogen-intense industries, such as heavy transportation (trucking, shipping, aviation) and cement or glass manufacturing.
The latest challenge to landfill gas management is the occurrence of increases in temperatures within the landfill waste mass, otherwise referred to as Subsurface Elevated Temperature Events (SET). SETs can create a variety of issues, including changes in landfill gas composition, noxious odors, rapid and severe waste settlement, and (sometimes hazardous) leachate seeps and outbreaks, all of which add to operator costs and challenges for facility management. SETs are generating landfill gas with higher temperatures, increased carbon dioxide and carbon monoxide, and decreased methane content, which create NSPS compliance issues. The exact reason for SETs is not yet well known. A combination of factors may be contributing to the rise in these events, such as abnormal chemical reactions from disposal of certain wastes or operational management practices. Methods to combat the spread or rise in intensity of these events include increasing extraction of landfill gas through increased density of well coverage through the SET area.
California is contemplating first-in-kind legislation that would significantly impact how landfills experiencing SETs are managed. Under AB 28, landfill operators would be required to take escalating actions based on the severity and duration of elevated temperatures in landfill gas. For example, landfill gas temperature at the wellhead in the range of 131°F to 145°F (for 60+ days) would result in the site being flagged as a SET. This in turn would require operators to prepare a Corrective Action Plan in coordination with local enforcement agency and CalRecycle. As conditions intensify, the duties to implement corrective action and oversight by state agencies increases. Penalties as high as $1 million a week could be imposed on a landfill operator for noncompliance. As of the writing of this article, the proposed legislation is on the Senate floor’s inactive file and could be heard in the current legislative session.
The next most likely challenge on the regulatory horizon is the regulation of per- and polyfluoroalkyl substances (PFAS) in landfill gas. PFAS in landfill gas is still being studied and is somewhat inconclusive at this time. Studies show that mainly PFAS-precursors, such as fluorotelomer alcohols, are being released, although little information exists regarding these precursors in landfill gas. Currently, PFAS perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS) are not regulated under the CAA. In 2021, Congress proposed the “PFAS Actions Act,” which would have required the EPA to add PFOA and PFOS to the list of hazardous air pollutants under the CAA, but the Senate did not move the bill. As of the writing of this article, no states nor the EPA regulate PFOA/PFOS emissions from landfills, and indeed, the management of PFAS in air emissions will present new challenges. For instance, how will landfill gas be monitored for PFAS? EPA is still developing test methods for laboratory testing of PFAS. Landfill gas sampling is typically monitored through handheld equipment used; the models in use today are unable to detect PFAS in the gas.
1 See 61 FR 9905-9944 (Mar. 12, 1996).
This article is provided for informational purposes only—it does not constitute legal advice and does not create an attorney-client relationship between the firm and the reader. Readers should consult legal counsel before taking action relating to the subject matter of this article.
