Colorado plans to regulate landfill methane emissions in 2025

Landfills in Colorado release millions of metric tons of greenhouse gasses each year as organic waste including food, paper and yard trimmings decomposes into the soil, contributing to global warming and harming human health.

Colorado, as part of its multi-pronged approach to eliminate 90% of the state’s greenhouse gas emissions by 2050, is planning to address those landfill emissions next year with rules that could require operators to install new equipment to curb the amount of methane they release and to increase monitoring technology to better track just how much is being generated.

The state’s Air Quality Control Commission is expected to create the new rules in August, which would place Colorado among the nation’s first states to enact more stringent regulations on landfills than the U.S. Environmental Protection Agency.

The state kicked off its efforts last week with the first of three public hearings to explain why environmental leaders want to regulate landfill emissions of methane, a far more potent pollutant than carbon dioxide, and how they would propose doing so.

Along with reducing air pollution, the methane reduction also would benefit communities in Colorado that live near landfills, where residents often are Latino, Black or Indigenous and earn less money than the average household.

Finally, reducing methane would also help the Front Range improve its air quality, which is in severe violation of federal ozone standards.

“Methane is an incredibly potent climate pollutant and reducing methane emissions from landfills is a very cost-effective climate action solution,” said Suzanne Jones, executive director of Eco-Cycle, a nonprofit recycler in Boulder. “And it’s an opportunity for Colorado to use its expertise on methane monitoring of oil and gas operations to apply to landfills as a model for the rest of the country.”

There are 51 active landfills in Colorado, and some are owned and operated by cities and counties, while others are owned by private companies. It’s unclear how many will be impacted by the new methane reduction regulations, since regulators have not finalized their proposal that would determine how big of a polluter a landfill would need to be to fall under the new rules.

Landfills are the third-largest source of methane emissions behind oil and gas production and livestock farming in the United States.

Colorado’s landfills released 1.45 million metric tons of greenhouse gases in 2020, the most current data available from the Colorado Department of Public Health and Environment. That’s 1% of all the greenhouse gas emissions in the state, Tim Taylor, a supervisor in the department’s climate change program, said during last week’s public hearing.

However, environmentalists and even federal and state regulators believe the amount of methane leaking from landfills could be much greater.

In June, a NASA study using satellite data estimated that landfills in the U.S. are releasing 50% more methane than the EPA reports, and a subset of 70 high-emitting landfills found emissions were 77% higher on median than what was reported to the EPA.

Only 21 of Colorado’s landfills are large enough to report their methane emissions to the EPA under current regulations, but they account for 76% of the industrial methane sources in the state, ahead of mining, manufacturing and food processing, according to a report released this month by Industrious Labs and Healthy Air and Water Colorado, a coalition of health care professionals fighting climate change.

Landfills are “living masses of waste” where food scraps, discarded paper products and landscaping material break down over the years and release methane along with other chemicals such as benzene and toluene, said Katherine Blauvelt, circular economy director at Industrious Labs, a group focused on reducing industry’s impact on climate change.

“Colorado landfills are responsible for the equivalent of 1 million cars on the road,” Blauvelt said. “Every little bit of methane you don’t put in the atmosphere has a positive impact. The way you do that is through basic regulations. In Colorado, it’s like we are on Windows 2000 technology.”

The EPA already requires larger landfills to control and report emissions, but Colorado is planning to expand those requirements to smaller landfills, increasing the number that will be regulated, Taylor said. Under the EPA’s requirements, landfills are regulated based on their designed capacity, but Colorado will order landfills to follow the new rules based on the amount of waste they already have in place, he said.

Landfills that fall under the threshold Colorado sets will be required to install gas collection and control systems to capture the methane, Taylor said.

Then the operator would have choices: Install an enclosed combustion flare so methane is burned off and turned into carbon dioxide, which is a less potent pollutant, or convert the methane into a natural gas that can be used in the electrical grid, Taylor said.

The state also is considering a requirement for landfills to use biofilters or biocovers to reduce methane emissions.

“Biocovers and biofilters are passive methods for reducing landfill emissions because they rely on naturally occurring microbes or methane-eating bacteria to convert methane to carbon dioxide or water without the need for any external energy input or active intervention,” Taylor said.

Environmentalists also are pushing the state for more monitoring of landfills, including the use of drones and satellite imagery to better detect leaks that otherwise might be unseen because of looser monitoring requirements. Employees at landfills that already monitor emissions do so once a quarter by walking the property with detection devices, Blauvelt said.

Air flights conducted to look for methane leaks from the sky have detected unreported plumes at multiple Colorado landfills, including the Tower Landfill in Commerce City, the Larimer County Landfill in Fort Collins and the North Weld Landfill in Ault, according to the Industrious Labs report.

At the Tower Landfill, there were nine large methane plumes detected by flights in September 2023 and August 2024. Those plumes were so large that they would have been considered super emitters by the EPA’s standards for the oil and gas industry, the report said.

The landfill, which is owned and operated by Republic Services, detected more than 20 instances that went over federal limits for methane emissions during a quarterly inspection in August. But “a landfill can leak methane more than quarterly,” the report said.

Colorado received a federal grant for aerial monitoring of methane emissions in the state and environmentalists hope it will be applied to regulating landfills, Blauvelt said.

“This is about common sense improvements based on what we know about methane,” she said.

Melissa Quillard, a Republic Services spokeswoman, said the August 2024 plume at Tower Landfill happened as the company was constructing a new landfill cell and had multiple pieces of excavation equipment running. That work temporarily exposed waste so that engineered liners and additional infrastructure could be installed, she said.

Quillard’s email did not address the September 2023 plume.

While Republic Services does not comment on pending rule changes, Quillard noted that gas coming from landfills fluctuates throughout the day based on the age and composition of waste, weather, construction and how the trash is being moved around the landfill.

Any monitoring and reporting techniques would need to take into account those dynamics, she said in a statement emailed to The Denver Post. Satellites and drones capture a moment in time and do not follow the EPA’s existing reporting model or provide a representative assessment of a landfill’s overall emissions, she said.

Republic Services owns three landfills in metro Denver, and the company is building a new organic waste facility in the area. Two of the local sites are in the early stages of developing projects that will convert methane to usable natural gas. And the company already uses capture-and-control systems to burn off methane, Quillard said.

One thing that will not be addressed as the landfill methane emissions rule is created is how to lower the amount of waste sent to landfills through expanded composting and recycling. That’s because this rule will be created by the Air Quality Control Commission, a body that can only set air pollution policies.

Brian Loma, the hazardous waste reduction advocate for GreenLatinos Colorado, hopes the state health department’s Hazardous Waste and Materials Management Division will push for improved composting and recycling at the same time the air quality commission takes up proposed methane rules.

GreenLatinos supports more regulation of landfills because so many Latinos live within a mile of trash dumps, forcing them to breathe dirtier air.

“The No. 1 way to reduce methane emissions is to not put organic material in the landfill,” Loma said.