The EPA has reached a $55 million settlement with Shell Oil Company and the US General Services Administration for the cleanup of contaminated soil at the Del Amo Superfund Site in Los Angeles, California.
The cleanup work will prevent surface exposure of industrial chemicals and reduce sources of groundwater contamination from across the 280-acre site, the EPA says.
The Del Amo facility was the site of a synthetic rubber manufacturing plant that was built in the 1940s and ceased operations in 1972. Benzene, propane, butylene and butane, used to produce synthetic rubber were disposed in unlined pits and ponds and covered with soil, resulting in contamination of soil and groundwater. The Del Amo Superfund Site was placed on the EPA’s National Priorities List in 2002. The GSA is the successor to the plant’s former federal government owners, the Defense Plant Corporation and Rubber Reserve Company. Shell was a former operator and eventual owner of the plant.
Part of the cleanup will involve injecting chemicals into the ground in three locations to accelerate the breakdown of the contamination deep within the soil. In addition, a vacuum system will extract and filter harmful vapors trapped within the soil. These treatment techniques are estimated to take three to five years to complete.
In addition, several areas will be capped by materials such as concrete and asphalt to prevent exposure to shallow soil contamination. To reduce the potential for indoor air pollution, one building will increase its ventilation or add floor sealants. The settlement also requires stricter building permit reviews and disclosures to ensure that no one is exposed to any residual contamination when conducting construction work at any of the businesses on the site.
The settlement, in the form of a consent decree, provides funding for the cleanup program and payment of the EPA’s and the state of California’s oversight costs. The settlement claim was brought by the US Department of Justice on behalf of the EPA, and the state of California also brought a claim on behalf of the Department of Toxic Substances Control.
To date, extensive investigations and cleanup actions have been performed at the Del Amo Superfund Site, including the construction of a multi-layer impermeable cap, soil-vapor extraction and a treatment system at the waste pits, and construction of a groundwater extraction and treatment system. In addition, during the spring of 2015, the EPA conducted indoor vapor intrusion testing at 107 homes in the area of the Del Amo and nearby Montrose Superfund Sites as part of an ongoing investigation.