ARCHIVED REPORTS XR0005968 - Laserfiche WebLink

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Lead was detected at concentrations ranging between 4 and 23 mg/kg in the soil samples. Normal background concentrations due to inorganic lead generally range from 5 to 15 mg/kg in the Stockton area. The detected concentrations therefore pose no health threat. The samples were also analyzed for several gasoline additives (ethers and alcohols) that are used in California clean-burning fuels. These oxygenated compounds include MTBE (methyl-tertiary- butyl-eiher), TAME (tertiary-amyl-methyl-ether), ETBE (ethyl-tertiary-butyl-ether), D1PE (di- isopropyl-ether), and TBA (tertiary-butyl-alcohol). MTBE was detected in two excavation soil samples, two stockpile samples, and both water samples (Table 1). TBA was also detected, but in both of the stockpile samples and in one of the water samples, the reported concentrations are approximate because the reported concentrations are less than the Practical Quantitation Limit (i.e. the product of the Reporting Limit x the Dilution Factor). MTBE and TBA are the only two oxygenates that had previously been detected in water samples from the wells. 7.0 SUMMARY Two 10,000-gallon unleaded gasoline tanks and associated piping and dispensers were removed from the Kwikee Foods property on March 3, 1998. Small holes were found in both tanks, implying that both were sources of unauthorized releases of gasoline over an unknown length of time. The total volume of gasoline that was released cannoi be estimated at this time, but examination of past inventory reports may provide some indication of the magnitude of the release. Soil samples collected from the excavated soil and from native soil at the base of the excavation at the north and south ends of both tanks confirm that soil in the vicinity of the tanks is contaminated with gasoline. The extent of this contamination is presently unknown, but should be investigated during the next phase of assessment. Our October 1997 work plan should be amended to include soil borings in and around the tank excavation. An addendum to this effect will be submitted in April 1998. Gasoline was observed as a sheen floating on groundwater at the base of the excavation, and was detected in groundwater samples. Monitoring of this contamination will continue on a quarterly basis as required by PHS/EHD. 4