The Los Angeles County Sanitation Districts (Sanitation Districts) own approximately 36 acres of land (Site) at our AK Warren Water Resource Facility in the City of Carson. Due to former use of the Site as an oil refinery, the Site needed remediation for petroleum hydrocarbon contamination before it can be re-developed. 

The Los Angeles Regional Water Quality Control Board (Regional Board) is the regulatory agency responsible for overseeing environmental investigation and cleanup work at the Site. The Regional Board issued a No Further Action letter to the Sanitation Districts in 2021, indicating that no further remediation is needed for the top 30 feet of the Site. (See Site in figure above.)

The Fletcher Oil and Refining Company (FORCO) operated at the Site from 1939 through October 1992.  Operations at the Site consisted of refining and storing petroleum products including crude oil, light distillates such as gasoline and naphtha, and intermediate and heavier distillates such as diesel fuel, heavy fuel oils, and asphalt. It is apparent that contaminant releases occurred during refinery operations.

The Sanitation Districts acquired the Site in 2000 and is remediating the Site to facilitate future development at the now mostly vacant property.  In 2015, the Sanitation Districts entered into an agreement with the Metropolitan Water District of Southern California for possible construction of an advanced water treatment facility at the Site to beneficially reuse treated wastewater from the Warren Facility.

An air sparge/soil vapor extraction system has been used to clean up petroleum hydrocarbon contamination in the soil and groundwater since 2004.  That system has recovered and destroyed 1.7 million pounds of petroleum hydrocarbons to date.  Previous soil excavations have also resulted in the treatment of more than 11,000 cubic yards of contaminated soil from depths up to 10 feet below ground surface.

The top 30 feet of the Site is now clean and ready for redevelopment, as determined by the Regional Board in 2021.  Nonetheless, the Sanitation Districts are still working to further clean up the deeper soil and groundwater.

Continued remediation efforts for deeper soils and groundwater will consist of expansion of the existing air sparge/soil vapor extraction system, installation of biosparge systems, and installation of a horizontal pulsed oxygen biosparge well to address off-site groundwater contamination. The initial phase of system expansion will be within areas of the greatest impact.  The system will be operated, maintained, monitored, and reported using an adaptive site management model.  The remediation systems may be modified and expanded as needed based on remediation data.

 This project has been funded wholly or in part by the United States Environmental Protection Agency under assistance agreement 4B-98T70301 to Sanitation District No. 2 of Los Angeles County. The contents of this document do not necessarily reflect the views and policies of the Environmental Protection Agency, nor does the EPA endorse trade names or recommend the use of commercial products mentioned in this document.