Over 80% of Landfill Methane Emissions Go Undetected Under Flawed Standards

Landfills are harming people and accelerating global warming. When organic waste, like food waste or yard clippings, is tossed in a landfill, it immediately begins decomposing into methane — a highly potent greenhouse gas and major contributor to climate change. Methane doesn’t travel alone. When it spews into the atmosphere, it carries along a toxic cocktail of co-pollutants — including benzene, PFAs, and hydrogen sulfide — all of which are associated with severe health conditions like asthma, heart disease, and cancer.

For decades, regulators have relied on a manual method to do Surface Emission Monitoring (SEM). Someone from a landfill, often a contracted consultant, will walk around a waste facility just four times a year with a methane detection device, walking a grid pattern spaced out 100 feet (30 meters) — the length of a full basketball court — and skipping the active working face of the landfill and areas where it is deemed too dangerous to monitor.  These methods are by definition labor-intensive, spotty, vulnerable to human error, and pose safety threats to the person monitoring, causing leaks to go undetected.

A new peer-reviewed study has found that this method fails to capture the majority of emissions. Dr. David Risk and researchers at St. Francis Xavier University in Canada tested manual surface emissions monitoring at ten landfills, using the same method that U.S. EPA and most states require.  First, they determined the actual methane emissions and location, utilizing mobile sensors and taking collecting about 50,000 geolocated concentrations measurements. Then, they used the manual SEM method and compared the results. 

They found that over 80% of methane went undetected. And a lot of that methane that manual monitoring missed was found to be coming from the active face of the landfill, or where trash is being dumped.  

Let’s just take a step back. In any other context, would we say an 80% failure rate is ok?  If a doctor screwed up their diagnoses over 80% of the time, would that be acceptable?  

And this isn’t the only evidence. Studies across North America and Europe have consistently found the same blind spots. Ute-Röwer et al. (2016) and Mønster et al. (2019) showed that SEM often fails to capture the patchy, uneven nature of landfill emissions — especially hotspots. In March 2024, scientists from Carbon Mapper, EPA, and others published a study providing the largest, most comprehensive assessment of hundreds of U.S. landfills using aerial surveys. Super-emitters — or very large releases of methane — were identified at 52 percent of landfills surveyed. On average, aerial emission rates were 40 percent higher than the EPA’s Greenhouse Gas Reporting Program (GHGRP), confirming a significant discrepancy between reported and actual methane emissions.

Examples of places where methane can escape through the surface of a landfill

Real-World Consequences: Republic Ignores over 90% of Landfill Surface 

Remember, landfills emit methane and other harmful pollutants 365 days a year.  Every day that passes, the problem gets worse. The Statesman Journal recently reported that at Republic-owned Coffin Butte landfill, Republic exempted more than 90 percent of the landfill surface from monitoring requirements.  This is the same landfill where EPA inspectors found explosive levels of methane and serious compliance issues. 

Valley Neighbors for Environmental Quality and Safety (VNEQS) and Beyond Toxics Oregon have been calling out this gap and pressing for stronger, more effective state rules from Oregon DEQ.  Meanwhile, the people living by the Coffin Butte landfill are shouldering the consequences, as are the school children in nearby schools.  Neighbors report days they cannot let their kids outside to play, and fear the river and well water are being contaminated.  

A Better Way Forward: Policymakers Should Ensure Landfills Use Proven Tools

The good news is that cost-effective, advanced methane monitoring technologies—including drones, fixed sensors and more —are already widely available and in use.  These tools provide far more accurate data than traditional manual monitoring that this study examined.  That’s why many landfills are already utilizing advanced monitoring like drones from Kansas to North Carolina. Again, these technologies are cost-competitive with the traditional manual monitoring  - making their adoption feasible for landfill operators. In fact, using remote sensing can actually reduce long-term costs by quickly identifying and fixing methane leaks before they worsen, rather than relying on costly reactive measures after the problem has already spread. 

The data from these systems also provides desperately needed transparency, giving regulators and the public access to real-time emissions tracking, ensuring accountability.

Risks’ study found a significant amount of methane emissions from the working face missed by manual SEM methods. Thankfully, there is a straightforward upgrade to regulations that can slash methane from the working face -  Require earlier installation of gas capture systems and leak detection. According to EPA’s own research, 50% of the carbon in food waste degrades into methane within 3.6 years. Yet current EPA federal rules allow five years to pass before landfill operators are required to expand gas collection systems. As a result, an estimated 61% of methane generated by landfilled food waste is released into the atmosphere. 

In addition, current regulations are absolutely silent on a major source of methane emissions - the working face of the landfill.  A Cal Poly field investigation of methane gas emissions from a representative set of California landfills recommended limiting the working face and concentration of wet waste as much as possible and, because daily cover had the most emissions potential, that intermediate cover should be installed within days — not weeks — of waste placement.

To protect communities, we need regulations that match the reality on the ground. State regulators should require more effective, comprehensive monitoring for methane leaks and institute common-sense best practices to limit working face emissions.