Operators of heaping trash piles will one day have to put a lid on their methane emissions, as Colorado begins the process of adopting stronger landfill rules.
Earlier in December, the state health department held the first of several public meetings to collect feedback about its proposal to curb emissions from municipal solid waste landfills that accept common household waste like food and plastic.
State law requires Colorado to reduce its greenhouse gas emissions in 2030 by 50 percent of 2005 levels. State health and environment officials, along with environmental advocates, believe that stricter landfill rules are low-hanging fruit to help reach that target. Organic waste like fruit is responsible for two-thirds of methane emissions from landfills, according to the state.
“Waste is one sector where Colorado has yet to take any additional actions to reduce greenhouse gases,” said Tim Taylor, a supervisor in the air pollution control division of the health department, during the meeting. “So this landfill methane rulemaking will really be our first foray.”
Colorado’s current landfill rules are set by the U.S. Environmental Protection Agency. The state has 51 active municipal solid waste landfills, according to Taylor, although only 21 have high enough emissions to be reported to the EPA.
Under the current rules, if large landfills emit enough of a hazardous class of compounds known as volatile organic compounds, operators must install systems to collect the wafting methane — a potent climate-warming gas. Ten landfills in Colorado meet those standards, Taylor said.
The problem, though, is that current standards for detecting methane may not detect how much is actually escaping into the atmosphere. Current rules require some operators to conduct “surface emissions monitoring” four times a year. That involves a technician walking the perimeter of a 100-foot grid on top of a landfill, and pointing a hand-held sensor at the ground to pick up emissions.
Under current rules, however, technicians are allowed to skip vast parts of landfills, including active areas where trash is being dumped, which may account for much of the emissions. Operators are also allowed to use drones to conduct the testing.
“It’s kind of like the approach of using a Windows 2000 operating system, and we gotta upgrade to today’s technology,” said Katherine Blauvelt of Industrious Labs, an environmental advocacy firm that released a Colorado landfill methane report.
Colorado landfills release around 1 percent of statewide greenhouse gas emissions, according to Taylor. But that’s likely an underestimate: An October NASA study found that U.S. landfill emissions may be 50 percent higher than what’s reported to the EPA.
Aerial flights and satellite imagery collected by the group Carbon Mapper found several massive methane plumes over the Tower Landfill in Commerce City, some of which happened outside of quarterly monitoring periods.
The proposed rules will likely require more landfills to wrangle their emissions than current EPA rules. The rules may also tighten the timeline for landfill operators to capture and burn leaking methane gas, which creates carbon dioxide and water, though regulators may phase out burning off methane through open-air flames known as flaring.
The state is also considering using “biocovers” and “biofilters,” which harness microbes to eat methane, which could be useful at less-polluting landfills. Blauvelt said that outside of new technology, fixes could be as simple as dumping enough dirt overexposed patches to tamp down leaks.
“You don’t have to split an atom to address and effectively prevent harmful emissions,” Blauvelt said.
The state is modeling its rules in part based on standards from California, Oregon, Maryland and Washington, which all have stricter rules than the EPA for landfill methane emissions.
In October, Colorado’s Air Quality Control Commission updated greenhouse gas reporting requirements for municipal solid waste landfills, in order to make way for these upcoming rules.
The state health agency will hold two more public information meetings before presenting proposed rules to the commission in April 2025. The commission might then begin formal rulemaking in August 2025.
