Rule Applicability
Why many high-emitting landfills escape basic federal standards to control emissions
The Problem
The U.S. EPA regulates landfill gas, not methane. The federal landfill methane rule uses a two-step trigger that is fundamentally misaligned with actual methane emissions. These criteria were first set in 1996 and have remained unchanged. First, EPA regulates non-methane organic compounds (NMOC) rather than methane itself. Yet methane is the dominant climate pollutant emitted from landfills. By tying applicability to NMOC emissions instead of methane generation or measured methane emissions, the rule uses an indirect proxy that means a landfill can be generating plenty of methane emissions, but still fall below the NMOC formula.
Second, the rule requires landfills to meet both:
A minimum design capacity of 2.5 million metric tons or 2.5 million cubic meters of waste. Methane generation, however, is driven by the amount of biodegradable waste actually in the landfill. A landfill can be permitted for 2.5 million Mg but take years to reach that volume. During that time, methane is being generated without triggering controls.
NMOC emissions of at least 34 Mg/year: Unfortunately, NMOC emissions are highly variable and not tied to methane generation.
Even the EPA’s own 2024 White Paper acknowledges that adjusting the landfill size threshold would bring hundreds more landfills under control sooner, capturing methane that is currently escaping unchecked. This structure also allows many landfills that emit substantial methane to escape regulation simply because they fall below one of the two criteria.
Recognizing this, a number of states have adjusted applicability of landfill air emissions requirements to better target large methane emitters, substituting in a calculated methane generation rate and actual waste-in-place figures. The methane generation rate is dependent on a number of factors including waste-in-place, age of the waste, type of waste (composition), and how much precipitation the landfill receives.
How States Have Closed Federal Gaps
The U.S. EPA regulates landfill gas, not methane. The federal landfill methane rule uses a two-step trigger that is fundamentally misaligned with actual methane emissions. These criteria were first set in 1996 and have remained unchanged. First, EPA regulates non-methane organic compounds (NMOC) rather than methane itself. Yet methane is the dominant climate pollutant emitted from landfills. By tying applicability to NMOC emissions instead of methane generation or measured methane emissions, the rule uses an indirect proxy that means a landfill can be generating plenty of methane emissions, but still fall below the NMOC formula.
Second, the rule requires landfills to meet both:
A minimum design capacity of 2.5 million metric tons or 2.5 million cubic meters of waste. Methane generation, however, is driven by the amount of biodegradable waste actually in the landfill. A landfill can be permitted for 2.5 million Mg but take years to reach that volume. During that time, methane is being generated without triggering controls.
NMOC emissions of at least 34 Mg/year: Unfortunately, NMOC emissions are highly variable and not tied to methane generation.
Even the EPA’s own 2024 White Paper acknowledges that adjusting the landfill size threshold would bring hundreds more landfills under control sooner, capturing methane that is currently escaping unchecked. This structure also allows many landfills that emit substantial methane to escape regulation simply because they fall below one of the two criteria.
Recognizing this, a number of states have adjusted applicability of landfill air emissions requirements to better target large methane emitters, substituting in a calculated methane generation rate and actual waste-in-place figures. The methane generation rate is dependent on a number of factors including waste-in-place, age of the waste, type of waste (composition), and how much precipitation the landfill receives.
Costs and Benefits
EPA estimates that once landfills hit the rule applicability threshold, design and construction of landfill gas collection and control systems (GCCS) typically cost $1–3 million per site, with annual operation and maintenance costs of $150,000–$400,000, and monitoring/reporting around $60,000 per year.
Budget challenges can be mitigated through bonding and by leveraging landfill gas energy. These practices can also save operators money by quickly identifying and remediating issues before they develop into more costly problems.
Exhaustive analysis of Colorado’s Regulation No. 31 found that publicly owned landfills face modest per-acre compliance costs while delivering benefit-to-cost ratios between 4.8 and 5.3, meaning every dollar spent yields nearly five dollars in climate benefits. Installing gas collection and control systems (GCCS) at the 18 landfills that currently lack them is expected to capture and destroy 12.3 million metric tons of CO₂-equivalent emissions. These reductions would also generate major economic benefits by avoiding climate damages. Using a 2.5% discount rate, the avoided climate costs from these emission reductions are estimated to be worth about $1.05 billion. Importantly, Colorado found that many publicly owned landfills were operating below thresholds requiring new gas collection systems, instead requiring monitoring or simple reporting.
In 2025, CARB estimated that needed updates to their regulations would deliver roughly three dollars in climate benefits for every dollar in compliance costs, driven by avoided social costs of methane and co-pollutant reductions. Even under a conservative assumption that 100 percent of compliance costs are passed through to residents, the estimated impact would amount to approximately $0.31 per person per year—a negligible cost relative to the benefits in avoided climate damage and improved air quality. CARB further found that improved methane controls would reduce emissions of toxic air contaminants and ozone-forming pollutants, delivering additional, unquantified public health benefits to nearby communities.
Industry Claim: Expanding landfill emissions rule applicability will impose unmanageable costs on small landfills.
Fact: Experience from hundreds of landfills operating under expanded applicability shows that stronger standards are workable, especially for publicly owned sites.
After adopting the lowest applicability threshold in the country (200,000 tons of waste-in-place), the Oregon Department of Environmental Quality found that 84 percent of locally owned landfills (32 of 38) only needed to submit a report. Just three landfills were required to conduct surface methane monitoring, and three were required to install or update an existing gas collection and control system (GCCS)—demonstrating that stronger rules primarily improve verification and accountability, not capital intensity (Oregon DEQ, 2021).
This pattern is consistent with outcomes in other states. Close to 400 municipal solid waste landfills across the country are already subject to updated state-level landfill methane requirements, including many of the same elements proposed here—earlier GCCS installation, tighter surface emissions monitoring, and enhanced operational oversight. Roughly 70 percent of these landfills are publicly owned, directly contradicting claims that public operators cannot comply with modern standards.
At the national level, concerns about municipal burden are further undermined by the structure of the landfill industry. The five largest publicly traded waste companies control approximately 61 percent of U.S. landfill volume, while local governments manage about 27 percent, with the remainder held by smaller private operators. As a result, most landfill capacity—and most methane emissions—are controlled by large, well-capitalized private firms, not cities or counties.
These firms operate within a U.S. waste and recycling sector valued at over $100 billion annually, with individual companies reporting billions in yearly revenue and net income. Against this backdrop, the compliance costs associated with modern methane monitoring and control represent a small operational expense, especially compared to the substantial climate, public health, and community benefits of reducing methane and toxic co-pollutant emissions.
Emissions Reductions
EPA’s modeling shows that lowering landfill size threshold across the country could result in a reduction of 538 million metric tons of CO₂-equivalent (Global warming potential - 100 years), by 2060 compared to the current standard. In other words, revising the threshold would deliver on the order of half a billion metric tons of additional climate pollution reductions by mid-century.
A study by Energy Vision found that if new collection systems are installed at all open landfills emitting at least 50,000 MT of CO2e annually, combined with early collection of gas and real-time auto-tuning technology, it would collectively cut annual MSW landfill emissions by 58.9% and total U.S. methane by 8.63% (59.2 million metric tons of CO2 equivalent) based on 2023 emissions (or 8.84% from total U.S. methane in 2020).
Emerging Concepts: Expanding Applicability Beyond Size
Lowering the waste-in-place threshold is one way to capture more methane sooner—but states are also exploring new, performance-based triggers that go beyond size altogether.
Remote Sensing as a Regulatory Trigger
Remote methane detection is an emerging tool for finding and verifying emissions - moving from a needle-in-a-haystack-approach to quickly identifying “super-emitter” sites that might not otherwise be regulated. EPA’s recent white papers highlight this as a key innovation for future landfill oversight.
Colorado and California have now incorporated remote sensing technologies into their landfill rules, allowing satellite, aircraft, or ground-based mobile instruments—certified under EPA’s Methane Super-Emitter Program—to identify big methane plumes.
Future state regulations could use persistent detections as an applicability trigger, requiring GCCS installation or other control measures even if a landfill is below the traditional WIP threshold. This approach transforms methane regulation from a static, size-based system to a dynamic, emissions-based system, ensuring that regulators can directly target the worst-performing sources regardless of size.
Biocover as an Alternative Applicability Pathway
For smaller or closed landfills where traditional gas systems are less cost effective or cannot be deployed due to lower levels of methane, biocovers—engineered soil layers enriched with methanotrophic bacteria—offer a biological control option that effectively substitutes for GCCS.
Under Colorado’s updated landfill rules, Regulation 31, closed or low-flow sites can replace gas control devices with biocovers or biofilters that oxidize methane biologically before release.
These systems must demonstrate surface methane ≤ 25% of the lower explosive limit and maintain conditions that support oxidation.
Once methane levels drop below 10%, ongoing monitoring and corrective action can end.
This represents a tiered compliance model, where smaller or end-of-life sites still reduce emissions meaningfully without the high costs of installing active gas collection.