California Tightens Landfill Rules After Fires and Methane Leaks Threaten Communities and Climate

A smoldering canyon of buried trash in the Santa Clarita Valley has produced geysers of liquid waste and foul-smelling gases that have drifted into nearby neighborhoods. Elsewhere in Southern California, surface fires have erupted at other landfills, an elementary school in the San Fernando Valley has occasionally canceled outdoor recess because toxic gases seeped from a nearby site, and animals tunneling into a former landfill in the Bay Area may have released explosive methane concentrations.

These incidents have focused attention on the state's landfill oversight. Decomposing food, paper and other organic waste produce methane and other hazardous pollutants — and experts say aging infrastructure, inadequate monitoring and regulatory gaps have allowed emissions and dangerous underground reactions to worsen.

What regulators are proposing

The California Air Resources Board (CARB) is poised to adopt a package of stricter rules for nearly 200 large landfills. Key elements include expanding the use of satellites, drones and other modern detection tools; requiring state-approved technologies to routinely scan areas operators deem inaccessible; and shortening response times when leaks or elevated temperatures are detected.

Under the proposal, landfill operators would have to repair detected leaks within three days (down from 10), limit gas-collection wells to five days of allowable downtime for repairs, and install gas-collection systems within six months of putting waste into a new cell instead of the current 18-month window. Operators would also need to disclose temperatures in their gas-collection systems and take steps to reduce oxygen if high heat is detected — a measure aimed at preventing the kind of underground combustion that can become nearly impossible to extinguish.

Incidents that prompted action

At Chiquita Canyon Landfill in Castaic, a chemical reaction beginning in May 2022 scorched roughly 30 acres of buried waste. By 2023 residents had submitted thousands of odor complaints citing headaches, nausea, nosebleeds and breathing problems. Inspectors later found temperatures above 200°F that melted plastic piping, saw geysers of liquid waste and white smoke venting from cracks, and detected elevated sulfur compounds and benzene. Air samples at a nearby park adjacent to Live Oak Elementary showed benzene concentrations more than eight times the state's short-term health limit.

The landfill's owner installed heat-resistant equipment to extract liquids and placed coverings over affected areas; the facility stopped accepting new waste and closed this year. Still, the hot reaction zone has expanded and could persist for years — similar underground landfill fires have remained active for over a decade in other places.

Earlier this year regulators also identified a high-heat "area of concern" at El Sobrante Landfill in Corona, where temperatures exceeded 200°F and surface fires had been observed. An analysis by California Communities Against Toxics found 18 landfills with prolonged heat signatures identified by NASA's thermal detection system, and public records show at least 11 received regulatory waivers to operate at higher-than-allowed temperatures.

Methane: climate and safety risks

Methane from decaying waste is California's second-largest source of this potent greenhouse gas after the state's large dairy and livestock industry. Over 20 years, methane traps far more heat than the same amount of carbon dioxide, making rapid reductions a powerful near-term climate strategy. Methane is also the primary component of natural gas and can create explosive conditions at certain concentrations; regulators have found potentially hazardous methane levels in air and shallow soil near some landfills.

This summer California partnered with the nonprofit Carbon Mapper to use satellites to detect methane plumes; the effort identified 17 distinct plumes from nine landfills between July and October. Under the proposed rules, CARB could require operators to repair leaks detected by satellite and to use approved scanning technologies where ground access is unsafe.

Costs, opposition and community impacts

CARB estimates the amendments could cost private companies and local governments about $12 million a year collectively. Many landfill operators and some local governments — including Sacramento County, which operates the Kiefer Landfill — say the new requirements would impose substantial operational burdens and higher costs that may be passed to residents through increased garbage fees.

Community members and environmental advocates counter that the public-health and climate benefits justify the expense. Residents affected by Chiquita Canyon plan to testify at the CARB hearing to describe how odors and pollutants have disrupted daily life. Val Verde resident Jennifer Elkins said she transferred her children to schools farther away and saw health improvements; another longtime resident, Abigail DeSesa, said the pollution has put families at risk of losing life savings tied up in their homes.

Advocates want regulators nationwide to stop issuing waivers that allow landfills to operate at elevated temperatures. "We would really like EPA and state agencies to stop granting landfill waivers. It's a permission slip to speed in a school zone," said Jane Williams of California Communities Against Toxics.

Assemblymember Pilar Schiavo said stricter rules may come too late to reverse damage at sites like Chiquita Canyon but could help prevent similar disasters elsewhere in the state. The Air Resources Board is expected to vote on the proposal this week.

Sources quoted: Bill Magavern (Coalition for Clean Air), Jane Williams (California Communities Against Toxics), Jennifer Elkins and Abigail DeSesa (local residents), Assemblymember Pilar Schiavo.