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Wendy L. Cohen -4- 4 October 1996 <br /> Monitoring wells BC9, BC 10, and BC 11 were not accessible for water level measurements in January <br /> 1996. BC9 and BC 10 were buried when a nearby canal was dredged and BC 11 is damaged. BC 17, a <br /> deep monitoring well (screened from 84 to 94 feet bgs), has not been sampled since October 1988. <br /> At that time, it had nondetectable concentrations of chloroform. <br /> Other Chloroform Investigations <br /> Two ground water investigations are being conducted in the vicinity of GP. The Triple E Produce <br /> facility is on Linne Road, approximately 1,700 feet east of MacArthur Drive and approximately <br /> 1.3 miles southeast of the GP site. Investigations at the site have shown that ground water consistently <br /> flows to the northwest from the facility and that chloroform from the Triple E facility has impacted <br /> domestic wells up to 5,000 feet from the chloroform source. Triple E is extracting ground water from <br /> two wells to remove chloroform from the source area and contain the plume. The established cleanup <br /> goal for chloroform at the Triple E site is 4.5 µg/1. <br /> The All Pure Chemical Packaging facility is on South Banta Road, east of the Tracy Defense Depot <br /> and approximately 2.5 miles east of the GP site. Investigations to date show that the shallow ground <br /> water flows southwest. Staff has requested All Pure to complete definition of the chloroform plume, <br /> but All Pure has not yet done so. Staff has not established a cleanup goal for chloroform at this site. <br /> Conclusions <br /> GP has not determined the extent of chloroform in ground water or remediated the contamination. <br /> The remediation system has been shut down since September 1991. Since then, only ground water <br /> monitoring has been conducted. <br /> In February 1985, staff set a cleanup goal for chloroform at 0.2 µg/l. The cleanup goal was revised <br /> to 5 µg/l in December 1991. The cleanup goal for chloroform at the nearby Triple E facility has been <br /> set at 4.5 µg/l. <br /> GP should re-evaluate the ground water contamination/remediation at its former Tracy facility. <br /> Considering the cleanup goal of chloroform to be 5 µg/1, GP should evaluate the effectiveness of the <br /> existing remediation system to remediate ground water in the source area and contain the full extent of <br /> the plume. This may require installing additional monitoring or recovery wells and possibly <br /> evaluating alternative remedial technologies. <br /> PAL:pal/lsb <br />