The Del Amo site covers 280 acres in Los Angeles, California, where a synthetic rubber plant operated from 1943 to 1972. Manufacturing wastes were deposited in unlined pits and evaporation ponds, releasing hazardous substances into soil and groundwater. The site was added to the National Priorities List (NPL), the federal list of priority Superfund cleanup sites, and most of the property has since been redeveloped into an industrial park. As of December 2024, 157 businesses operate there, employing more than 4,300 people.
EPA has identified 39 contaminants of concern across the site. These include benzene, toluene, ethylbenzene, and xylene in soil and groundwater, along with chlorinated solvents such as trichloroethene and tetrachloroethene, petroleum hydrocarbons, metals including arsenic and copper, and polynuclear aromatic hydrocarbons. Contamination affects soil, non-aqueous phase liquids (NAPLs, meaning dense liquid chemicals that do not mix with water), waste pits, and groundwater. No contamination has been detected in drinking water supplies serving nearby communities including Torrance, Carson, and Gardena.
Cleanup is divided into three operable units (OUs), which are distinct areas or problems addressed separately. OU-1 covers soil and NAPLs. A soil vapor extraction system was installed in May 2023, and in March 2025, EPA deleted 46 acres from the NPL after completing cleanup there. OU-2 covers the former waste pits, which have been capped and are now in an operation and monitoring phase. OU-3 addresses groundwater, with an active pump-and-treat system running for the chlorobenzene plume and monitored natural attenuation applied to the benzene plume. Cleanup is being carried out by responsible parties under oversight from EPA and the California Department of Toxic Substances Control.
EPA completed its most recent five-year reviews in September 2025. All three cleanup areas were found to be short-term protective, meaning current systems are protecting human health and the environment now. Long-term protection still requires additional work. For groundwater, cleanup plans for the trichloroethylene and benzene plumes need to be finalized. For soils, further cleanup is needed in source area 11 in the southeast corner of the site. For waste pits, soil monitoring must continue to confirm cleanup goals are met.
EPA held a virtual public meeting on April 21, 2026 to discuss cleanup updates at Del Amo and the nearby Montrose Superfund site. Residents with questions can contact the EPA staff assigned to this site and/or review site documents at local libraries in the Carson and Torrance area.
