Los Angeles County is turning up the pressure on the operators of the Chiquita Canyon Landfill in Castaic, ordering them to seal the sprawling dump under a specialized, thick geomembrane cover to trap noxious odors and landfill gases. The move comes after years of mounting complaints from nearby neighborhoods about foul smells and health symptoms tied to a subsurface elevated-temperature reaction that began in 2022. A county hearing board recently refused the landfill’s appeal and left in place a compliance order that sets a firm deadline for full cover installation.
What the county ordered
According to MyNewsLA, the Los Angeles County Local Enforcement Agency, part of the Department of Public Health, prevailed before the Solid Waste Facilities Hearing Board, which voted 3-0 to deny the landfill’s appeal and uphold the county’s Directive 4.1. That compliance measure requires a thick geomembrane cover over the entire facility and sets August 31, 2026, as the target date for installation, including a disputed 66-acre portion of the site. The county’s fact sheet notes that interim soil covers have not been fully effective and that the membrane is intended to cut gas migration and the off-site odors that have been hitting nearby neighborhoods.
Smoldering reaction and health complaints
Federal investigators have traced the underlying problem to a subsurface elevated-temperature reaction that began in 2022 and has produced increased landfill gases and hazardous leachate, the U.S. Environmental Protection Agency has reported. The EPA and local reporting describe residents filing thousands of odor complaints in 2023 and 2024, along with reports of eye and throat irritation, headaches, and anxiety. Regulators say the reaction has damaged some of the landfill’s gas-control systems and has triggered a multi-agency response aimed at limiting community exposure.
Landfill response and progress
The landfill’s operator says crews have been installing 60-mil EVOH/HDPE geomembrane panels as part of Mitigation Measure 4.1 and has been posting weekly progress updates on its public portal. Operator filings indicate that roughly 1.2 million square feet of geomembrane had been placed as of late February, while noting that wet weather and technical constraints have slowed the pace of work. The company continues to argue that the subsurface event is a chemical reaction rather than an open fire, even as regulators press for faster mitigation and more robust monitoring on and around the site.
Regulatory and legal backdrop
Los Angeles County has backed up its enforcement orders with a courtroom fight. The county filed a federal lawsuit against the landfill owners in December 2024 seeking injunctive relief and other remedies, according to disclosures in the owner’s public securities filings. State and regional agencies, including a CalEPA-led multi-agency team and the South Coast AQMD, remain heavily involved in oversight and technical review of the landfill’s mitigation plans. Those filings and state summaries indicate that regulators are prepared to seek additional orders, fines, or court remedies if current measures fail to quickly reduce off-site impacts.
What comes next for residents and regulators
With the hearing board’s ruling and the LEA’s Directive 4.1 now locked in, the operator is required to complete the geomembrane installation by August 31, 2026, while also carrying out complementary fixes such as leachate aeration and structural buttressing. The EPA’s facility updates list near-term targets, including leachate aeration expected in May and a west-toe buttress scheduled for completion in the fall, as part of a broader containment strategy. Local officials and residents say they intend to keep tracking air-quality complaints and expect independent confirmation that the cover and related measures actually reduce odors and lower community exposures.
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Sources: MyNewsLA; Los Angeles County Department of Public Health; U.S. EPA; Los Angeles Times; Chiquita Canyon operator update; CalEPA; Waste Connections SEC filing.
