Remediation of the upper aquifer at the Beckman Instruments, Inc. , Superfund site, Porterville, California

Concentrations of volatile organic compounds, including 1,1,1-trichloroethane (1,1,1-TCA) and 1,1-dichloroethylene (1,1-DCE), were identified as present in ground water in a shallow alluvial aquifer in the vicinity of the Beckman Instruments Plant in Porterville, CA. A comprehensive program of ground-water characterization was initiated by Beckman Instruments Plant in Porterville, CA. A comprehensive program of ground-water characterization was initiated by Beckman in 1983, followed by installation and start-up of a ground-water remediation system in mid-1985. The selected remediation method was pump-and-treat utilizing two separate extraction wellfields with associated air stripping towers. Between June 1985 and September 1989, maximum concentrations of 1,1,1-TCA in upper aquifer ground water decreased from 2,000 micrograms per liter ([mu]g/1) to less than 25 [mu]g/1. During this same time period, maximum concentrations of 1,1-DCE in upper aquifer ground water decreased from140 [mu]g/1 to 4 [mu]g/1. Cleanup goals designated by EPA for upper aquifer ground water were 200 [mu]g/1 for 1,1,1-TCA and 6 [mu]g/1 for 1,1-DCE. Upper aquifer remediation was discontinued in January 1990 upon meeting upper aquifer cleanup goals. Since then, concentrations of 1,1,1-TCA and 1,1-DCE in upper aquifer ground water have continued to decrease.