Dive Brief:

• Colorado’s Department of Public Health & Environment is pressing forward with a range of modifications to landfill gas emissions requirements, including earlier installation of gas collection and control systems and the adoption of technologies like aerial monitoring and biofilters.
• The draft rule aligns Colorado’s rules more closely with states such as California, Washington and Maryland that exceed federal requirements. Landfill operators WM and Republic Services weighed in on the proposal during a technical advisory process last year, as have environmental justice groups.
• CDPHE held its final public meeting last week to discuss the landfill methane rule. It plans to submit its proposed rule to the state’s Air Quality Control Commission in April.

Dive Insight:

The state is looking to mitigate greenhouse gas emissions through the rule. In 2020, landfills emitted 1.445 million metric tons of carbon dioxide equivalent in Colorado. 

Federal regulations for landfill air emissions are designed to address non-methane organic compounds. Landfills are expected to install a gas collection and control system after reaching a certain level of permitted capacity. Those systems can in turn divert methane gas, a potent climate pollutant, to generate electricity or produce pipeline-quality renewable natural gas.

But researchers have discovered inefficiencies and gaps in those systems where methane can escape. 

The state is planning to set a waste-in-place threshold at 450,000 tons, after which operators must measure their methane generation rates. The waste-in-place threshold is lower than federal standards. Closed landfills would also be required to submit a one-time waste-in-place report to regulators, according to language shared by CDPHE during public meetings.

Regulators are planning to require landfills to install gas collection systems after reaching a certain methane generation rate. They expect to set that threshold lower than what any other state has required, Tim Taylor, a supervisor in CDPHE’s Climate Change Program, said at the agency’s Feb. 26 hearing.

Walking surveys of surface emissions would be required to follow a path with 25-foot spacing, as opposed to 100-foot spacing in federal requirements. The state would also increase expectations around when landfill operators must address detected methane emission plumes.

The state also plans to require gas collection systems be installed earlier than federal requirements, including by installing horizontal wells in the working face of a landfill. 

The state is also planning to allow a range of technologies to monitor and measure landfill gas emissions, including drones, planes and satellites. Those technologies have seen rising adoption as a more accurate means of monitoring emissions than walking surveys. The technologies are also able to measure emissions in areas of landfills that are unsafe for a person to walk — Colorado is considering requiring the use of technologies for those areas.

The state is also proposing the use of biocovers or biofilters on the face of landfills. Such systems include the installation of a porous layer like sand or gravel and a second organic layer like compost, which contains bacteria that can break down methane. Biofilters use similar cover materials and include the use of a piping system to route gases through such methane-destroying media. Colorado would be the first state to propose the use of such systems, which Taylor said are ideal for small or closed landfills with declining methane generation rates where a flare may not be as effective.

Environmental groups have largely praised regulators’ efforts to tighten landfill emission requirements, while urging the state to adopt measures that are maximally protective of fenceline communities. The rule proposal would end the use of open gas flares by requiring them to be enclosed, which CDPHE staff say would reduce pollutants impacting those communities.

Others questioned how the requirements would impact landfill operators and the waste sector more broadly. Craig Fuller, a Delta County commissioner, said requiring the installation of gas collection systems could be prohibitively expensive for rural counties that own their landfills. 

Representatives from major waste companies WM and Republic Services were members of a technical working group that held six meetings. They weighed in on issues like operational and maintenance requirements for gas collection systems. They also provided feedback on the timing for when gas collection systems should be installed.

Questions remain about the relative benefits of promoting organics diversion alongside landfill gas systems, according to Suzanne Jones, executive director of **nonprofit** Eco-Cycle. She said composters in the state had expressed concern to her organization, which promotes zero-waste strategies, that “landfill operators are going to have to choose between investing in landfill gas collection systems or advancing their organics diversion operations at the landfill.”

“While we know waste that's already in the landfill is going to continue to emit … it's really important I think that we recognize that diverting organics at the landfill is a key methane reduction strategy and landfill operators need to be able to pursue both of these and should be encouraged to do so,” she added.

Other outside forces may also impact the rule. Colorado was selected to receive $129 million from the **U.S. EPA? federal government** through the Climate Pollution Reduction Grants program. Of that, $23 million was designated for **CDPHE’s the** Air Pollution Control Division for methane monitoring efforts, according to an agency spokesperson.

But Taylor said the status of that funding remains uncertain, given the Trump administration’s attempts to claw back funding contracted out under that program. He said CDPHE is still planning to move forward with its plan to require operators to respond to third-party landfill gas plume detections, though the agency may “reassess how it might be implemented depending on what happens in the future.”