Across the United States, there are more than 2,500 municipal solid waste landfills. As buried food scraps, yard clippings, and cardboard decompose in these landfills, they generate methane: a powerful greenhouse gas with more than 80 times the near-term warming potential of carbon dioxide. Beyond the significant warming impacts, landfills release hazardous air pollutants, pungent odors, and ozone precursors, which can harm the health and quality of life of neighboring communities. More than 36 million Americans live within three miles of a landfill.

For these communities, reducing landfill pollution is one of the most impactful and cost-effective ways to slow near-term warming while also improving air quality, protecting public health, and boosting the local economy. Local governments are well positioned to implement solutions. Many counties own and operate their local landfills and thereby have direct control over landfill design and management decisions, while others can advance best management practices through contracts with the private sector. In this article, we describe the top five opportunities to cut landfill methane pollution and the benefits of acting today.

Mitigating methane through improved monitoring and control

While solid waste and air regulations set minimum standards for landfill pollution control, there is a substantial opportunity to improve landfill design, operations, and monitoring beyond regulatory requirements to better control methane, odors, and other health-harming pollutants. This article does not provide a comprehensive list of all methane control strategies, but rather highlights five high-impact and cost-effective measures that local government could consider, in consultation with professional engineers. These strategies have already been embraced by leading operators across the country.

Early installation and expansion of the GCCS is one of the most effective strategies to increase methane capture over the landfill's operational life, especially from fast-decaying materials like food waste. Current federal regulations allow up to five years to pass before GCCS expansion, during which significant emissions escape capture. However, it is technically feasible and cost-effective to install and expand the GCCS as waste is being placed, before this federal threshold is triggered. In fact, Michigan law requires that all new and expanding landfills have an active GCCS installed prior to waste acceptance. Horizontal collectors, slope collectors, bottom-up caisson wells, and gabion cubes can all be leveraged to support early gas collection at landfills.

Once the GCCS is in place, wellfield monitoring and tuning are critical to ensure that the system is functioning effectively. Automated systems take continuous measurements of landfill gas composition, flow, temperature, pressure, and liquid levels and adjust the GCCS to increase methane capture and reduce fugitive emissions. Compared to manual monitoring and tuning, real-time control systems can improve overall gas collection efficiency by at least 10%-20%, while alerting operators to other potential issues to inform faster mitigation. These systems are more cost-effective than manual tuning over time and have already been deployed at more than 140 North American landfills.

Once landfill gas is captured, it must be destroyed, recovered, or treated to minimize venting and leaking into the atmosphere. As such, landfills should ensure that all destruction devices and energy recovery systems achieve a methane destruction efficiency of at least 99% by weight and that any flares used at the landfill are enclosed. All flares, recovery devices, and treatment systems should be equipped with a gas flow rate measuring device that records at least every 15 minutes, and devices should undergo annual performance tests. The cost-effectiveness of these measures is well documented.

Landfill cover, which is material used as a protective barrier over buried waste, plays a critical role in methane mitigation. Recent remote sensing surveys have identified significant emissions coming from the landfill's working face (or active fill area), which can dominate total site emissions. Fugitive emissions generally decrease with the order of daily, intermediate, and final covers; high to low permeability covers; and thin to thick covers.

To better control surface emissions, landfill operators can minimize the size of the working face, reduce lag times for cover installation, use materials that promote oxidation, and monitor frequently to ensure cover integrity. Biocovers can be applied as intermediate or final cover at sites with or without active GCCS, to boost methane oxidation and control volatile organic compounds. Biocovers typically consist of a layer of organic oxidizing material, densely populated by methanotrophic bacteria, over a layer of coarse materials that promote even gas distribution.

Comprehensive monitoring is essential to effectively identify and repair leaks and ensure proper functioning of the gas collection system, cover, and destruction devices. There are significant gaps in conventional landfill monitoring protocols: walking surveys conducted with handheld equipment often miss emissions that could be mitigated due to incomplete spatial coverage, infrequency, and susceptibility to human error and manipulation.

Fortunately, advancements in methane monitoring technology — from satellites to aircraft to drones and fixed sensors — can fill these gaps. Compared to manual methods, they offer broader coverage, more frequent or even continuous data, and a more replicable and objective approach. These tools can enhance operators' leak detection and repair efforts, inform landfill design improvements to prevent emissions, enhance transparency by making data quickly accessible to the public, and keep workers and communities informed and safe.

These technologies are cost-effective, widely available, and already deployed by leading states and operators to identify and reduce emissions. There are dozens of technology vendors, and the per-survey cost is often a fraction of walking surveys.

Reducing organic waste disposal in landfills is the most effective solution for preventing future methane generation and promoting resource recovery. This approach includes reducing and redistributing surplus food and recycling the remaining organic waste. For example, minimizing on-farm losses, improving food inventory practices, and donating excess edible food to shelters or converting it to animal feed all help keep organics out of the waste stream. Remaining organic waste can then be separated and processed into compost, biogas, or other beneficial end products.

Successful organics diversion programs typically require enabling policies, adequate infrastructure, and robust end markets for waste-derived products. Organics recycling infrastructure, such as composting and biogas facilities, can also be co-located at the landfill.

Some of the strategies described above involve upfront capital costs, such as a new GCCS or composting facility. Other best practices, such as earlier GCCS expansion or cover installation, have little effect on total cost — they simply shift expenditures earlier. And many of these strategies can actually generate cost savings for operators or unlock new revenue streams by selling captured gas or compost.

For example, advanced monitoring surveys are typically a fraction of the cost of walking surveys, and automated wellhead tuning is more cost-effective than manual tuning over time. These practices can ultimately also save operators money by quickly identifying and remediating issues, such as a flooded well or fire risk, before they develop into more costly problems. Furthermore, earlier gas capture and improvements to wellfield tuning, cover, and monitoring can all increase gas flow to energy projects, boosting revenue.

The environmental, health, and economic benefits of methane mitigation far exceed any implementation costs. Colorado, for example, estimated a 6:1 benefit-to-cost ratio in its proposed landfill methane rule.

• Climate: More effective landfill methane control helps slow near-term warming and reduces the risk of extreme weather events, which can cost counties millions.
• Air quality and public health: Stronger landfill pollution controls reduce local exposure to odors, ozone, and health-harming compounds in landfill gas — protecting workers and communities.
• Economic opportunity: Capturing landfill methane can generate new revenue streams for local governments through energy projects or carbon markets. Closed landfills can also be repurposed to host solar panels. Organics diversion strategies can create jobs, reduce food insecurity, and generate valuable products like compost, which boosts soil health and crop yields.

For landfills that need support incorporating these technologies, financing strategies are available and will vary by county and local context. For some landfills, costs to implement these best practices can be covered within the annual operating budget or could be offset with moderate increases to tipping fees. Others may need to pursue municipal bond financing, lease financing, project finance, or private equity, or may be eligible for state or federal grant programs supporting climate pollution reduction. Leveraging voluntary carbon markets to monetize additional methane captured can also create a revenue stream to help offset costs.

Local governments are integral to waste management and well-positioned to make progress curbing methane pollution. Jurisdictions with direct control over landfill design and operations can implement these strategies today. Local governments that outsource landfill operations to the private sector can integrate best practices into contracts, permits, or host-community agreements with private sector entities. Communities without landfills can focus on waste prevention and organics diversion strategies, while ensuring remaining landfill-bound waste generated in their communities is sent to landfills that adopt these best practices. States can support local implementation of landfill methane mitigation strategies through guidance, funding, and regulations.

Landfill methane mitigation offers a fast, actionable opportunity to slow near-term warming. A 15% reduction in landfill methane emissions nationwide would reduce more than 43 million tons of carbon dioxide equivalent annually, which has roughly the same climate benefits as taking 10 million gas-powered cars off the road for a year. By taking action today, local governments can address one of the largest sources of climate pollution, while delivering real benefits locally: cleaner air, healthier communities, and new economic opportunities.