Landfill Methane Rules and Organics, What Landfill Owners Need to Know

Landfill methane rules regulate the gas a landfill produces, not the waste that goes into it: federal rules under 40 CFR part 60 and part 62 require larger landfills to estimate emissions, monitor the surface and install gas collection and control once thresholds are crossed, and some states, such as California and Maryland, go further. Organic waste is the main source of that gas, so diverting food and yard material to composting reduces how much gas the landfill makes in the future. It does not reduce the gas from waste already in place, and it does not by itself bring a site into compliance.

Key takeaways

The federal framework has three parts: standards for newer landfills (40 CFR 60 subpart XXX), emission guidelines for older landfills (40 CFR 60 subpart Cf) carried out through state plans, and a federal plan (40 CFR 62 subpart OOO) where no state plan is approved.
The key federal triggers are a design capacity of at least 2.5 million megagrams and 2.5 million cubic meters, and an estimated nonmethane organic compound (NMOC) emission rate of 34 megagrams per year or more.
California’s Landfill Methane Regulation is stricter and uses its own thresholds. CARB says amendments approved by the Office of Administrative Law take effect January 1, 2027.
Food waste decays fast. EPA estimates it is the source of about 58% of fugitive methane from municipal landfills, and it can produce methane before a collection system is installed.
Composting diverted organics lowers future gas generation and supports state diversion mandates. Treat it as one part of a methane strategy, alongside a working gas system.

Why organics drive landfill gas

Landfill gas comes from the anaerobic breakdown of organic material buried in the cells. EPA’s Landfill Methane Outreach Program describes it as roughly 50% methane and 50% carbon dioxide, and reports that municipal landfills were the third-largest source of human-related methane emissions in the United States in 2022, about 14.4% of the total. EPA also notes that methane is at least 28 times more effective than carbon dioxide at trapping heat over a 100-year period.

Food is the critical material. EPA’s research on landfilled food waste finds that food makes up about 24% of municipal waste disposed of in landfills, that its quick decay rate makes it the largest methane producer of any landfilled material, and that an estimated 58% of fugitive landfill methane comes from it. The same research points out that food can generate methane before landfill gas collection systems are in place, which is the gap a collection system cannot close on its own.

The federal framework

Three rules, one structure

Rule	Applies to	How it works
40 CFR 60 subpart XXX (new source performance standards)	Landfills that commenced construction, reconstruction or modification after July 17, 2014	Federal standards apply directly
40 CFR 60 subpart Cf (emission guidelines)	Landfills that commenced construction, reconstruction or modification on or before July 17, 2014	States write plans that carry out the guidelines
40 CFR 62 subpart OOO (federal plan)	Older landfills that accepted waste after November 8, 1987 or have capacity left, in places without an approved and effective state plan	Federal requirements apply until a state plan is approved

EPA’s landfill rules page lists the 2016 final standards and guidelines, a 2017 reconsideration and stay, 2020 amendments, the 2021 final federal plan, and a non-regulatory docket EPA opened in October 2024 to gather information on new technologies and work practices, with comments accepted until May 23, 2025. As of October 2026 the page lists no later rule action. Check it for changes before you rely on this summary.

The thresholds that matter

Under subpart XXX and subpart Cf, the main triggers are:

Design capacity. A landfill with a design capacity of at least 2.5 million megagrams and 2.5 million cubic meters must estimate and report its NMOC emission rate, and it falls under Title V operating permit requirements.
NMOC emission rate. If the estimated rate is below 34 megagrams per year, the owner reports it and recalculates annually. At 34 megagrams per year or more, the owner must install and start a gas collection and control system within 30 months of the report, unless more detailed sampling shows the rate is lower. Subpart Cf uses 50 megagrams per year for its closed landfill subcategory.
Surface monitoring. Once a collection system is required, the owner must keep surface methane below 500 parts per million above background and check it quarterly. Tier 4, an optional quarterly surface monitoring method, can be used instead of installing a system only where the estimated NMOC rate is at least 34 but below 50 megagrams per year.
Control. Collected gas goes to a flare meeting federal parameters or to a control device designed to reduce NMOC by 98 weight-percent (or, for an enclosed combustion device, to an outlet concentration below 20 parts per million by volume as hexane at 3% oxygen).
Removal. A collection system may be capped or removed only when the landfill is closed, the system has run at least 15 years (or cannot run that long because gas flow has declined), and the NMOC rate is below 34 megagrams per year on three successive tests.

How waste composition enters the calculation

The NMOC estimate is driven by the mass of waste placed. The default (Tier 1) values in subpart XXX are a methane generation rate constant (k) of 0.05 per year, a methane generation potential (L0) of 170 cubic meters per megagram, and an NMOC concentration of 4,000 parts per million by volume as hexane, with k set at 0.02 per year in areas averaging under 25 inches of precipitation a year. Those defaults do not change with the share of food in your waste. Tons kept out of the landfill lower the mass in the equation, and the faster decay of food is only reflected if the owner measures a site-specific decay rate (k) under the Tier 3 procedure. Tier 2 measures a site-specific NMOC concentration, not the decay rate.

The practical point for a landfill owner: diversion lowers future generation in the real landfill, while the regulatory estimate responds mainly to tonnage. Do not promise a board that a diversion program will delay a collection system trigger without your landfill engineer running the numbers.

State landfill methane rules

States can and do go beyond the federal floor. Two examples verified as of October 2026:

California

The California Air Resources Board’s Landfill Methane Regulation requires municipal landfills to reduce methane and other air pollutants through emissions monitoring and capturing fugitive methane. Under 17 CCR 95463, landfills with 450,000 tons or more of waste in place must calculate their landfill gas heat input capacity, and at 3.0 MMBtu per hour recovered or more they must meet the collection and control requirements or show, over four consecutive quarterly monitoring periods, no surface reading of 200 ppmv or more. The surface standards in 17 CCR 95465 are 500 ppmv instantaneous and an average of 25 ppmv by integrated monitoring. CARB states that its amendments have been approved by the Office of Administrative Law and take effect January 1, 2027, so check the amended text before planning monitoring.

California’s diversion law is separate. SB 1383 is an organics diversion and procurement law run by CalRecycle, not an air rule. CalRecycle says organic waste in landfills emits 20% of the state’s methane and summarizes the 2025 target as 75% less organic waste sent to landfills. See our list of key SB 1383 requirements.

Maryland

Maryland has its own chapter, COMAR 26.11.42, Control of Methane Emissions from Municipal Solid Waste Landfills, which applies to owners and operators of municipal landfills that accepted waste after November 8, 1987, with exclusions for certain closed or inactive landfills and for sites that take only inert or non-decomposable waste.

Other states have adopted or proposed rules of their own. Read your state agency’s current text rather than assuming the federal thresholds apply.

Where composting fits a landfill methane strategy

A landfill owner has four levers on methane: collect and control what is generated, cover and monitor to cut surface leaks, use the gas, and reduce the organic material coming in. Composting works on the fourth lever.

Lever	What it addresses	What it does not address
Gas collection and control	Gas from waste in place, once wells reach it	Gas generated before wells are installed in new cells
Cover and surface monitoring	Leaks through the cover	How much gas is generated
Gas use or destruction	Converts collected methane	Uncollected methane
Organics diversion to composting	Future generation from food and yard waste	Gas from waste already buried

A compost facility has its own air questions. In parts of California, compost operations face VOC rules from their air district, which is why the method matters. SG’s article on air quality rules reshaping compost facility design gives its view, and our list of covered composting systems for California air rules compares options.

Sustainable Generation (SG) supplies covered aerated static pile systems with the GORE® Cover and positive aeration controlled by oxygen and temperature feedback through the SG COMPOST CONTROL™ System. SG reports greater than 95% VOC control in third-party testing. Covered ASP with a GORE Cover is designed to contain odors at the pile. SG’s profiles of the Miramar Greenery and the Otay Landfill describe food and yard waste composting on landfill property; Otay was announced by Republic Services as California’s first fully solar-powered compost facility.

A step sequence for landfill owners

Confirm which rules apply. Construction date, design capacity, state plan status and any state rule decide whether XXX, Cf through a state plan, the federal plan or a state chapter governs your site.
Get the current NMOC estimate and the year it is projected to cross the next threshold, from your engineer.
Quantify the organics in your incoming waste using a characterization study or state data. The airspace and diversion guide shows how.
Ask your engineer to model diversion scenarios, including whether site-specific sampling would change the estimate. Treat the result as a projection, not a compliance outcome.
Check your state’s diversion mandate, because it may require the diversion anyway.
Screen a compost site on or beside the landfill, protecting wells, headers and probes.
Pilot the composting method with your own feedstock and record emissions and pathogen reduction data.
Report the program in plain terms. Describe it as reducing future methane generation, not as a substitute for gas collection.

FAQ

Does composting food waste bring a landfill into compliance with methane rules?

No. Methane rules govern gas generated, collected and leaking from the landfill, including waste placed years ago. Composting reduces the organic material added from now on, which lowers future generation. It does not replace a required collection and control system, surface monitoring or repairs. Present it to regulators and boards as part of a methane strategy.

Which federal rule applies to our landfill?

It depends on when the landfill commenced construction, reconstruction or modification. After July 17, 2014, subpart XXX applies directly. On or before that date, the emission guidelines in subpart Cf apply through your state’s approved plan, or through the federal plan in 40 CFR 62 subpart OOO where no approved plan is in effect. Your state air agency can confirm.

Will diverting organics delay the NMOC threshold?

Possibly, but not as much as the real reduction in gas. The default federal calculation uses the mass of waste placed and fixed decay values that do not vary with food content, so it responds mainly to tonnage. Site-specific testing may show a different result. Ask your landfill engineer to model it before you count on it.

Is SB 1383 a landfill methane rule?

No. SB 1383 is California’s organics diversion and procurement law, run by CalRecycle. It aims to cut the organic waste sent to landfills, which reduces methane, but landfill gas collection and surface monitoring fall under CARB’s Landfill Methane Regulation and the federal rules.

Next step

Start with the numbers: read the airspace and diversion guide to estimate what your organics are worth in volume and gas. For the composting process itself, see how covered aerated static pile composting works.

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