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#n KLEINFELDER was drilled through the backfilled tank excavation, it is possible that the low and (• inconsistent levels of gasoline and benzene detected in the well duringw the first two 4 sampling events may have been induced during the drilling and well completion. r Kleinfelder recommends that Nor-Cal Beverage seek closure of the site as , an environmental concern, and approval from San Joaquin County Public Health Services to ` abandon the well. Based on the following results, Kleinfelder does not recommend additional ground water monitoring wells or assessment. y • The monitoring well was drilled through the approximate center of the backfilled tank excavation in an area likely to encounter the vertical migration of petroleum hydrocarbons if present. • Elevated petroleum hydrocarbon concentrations were not detected in the two soil borings drilled vertically to a depth of 40 feet. These borings were drilled in the vicinity of elevated petroleum hydrocarbon concentrations remaining• in the excavation after soil removal. r The bulk of the contaminated soil and source of potential future contamination was removed during the tank and soil excavation activities. I • Ground water is approximately 70 feet below the ground surface and approximately 50 feet below the remaining two elevated petroleum hydrocarbon areas- detected in the excavation. The site is currently capped with asphalt, thus reducing the potential for surface water infiltration and the vertical migration of hydrocarbons to the ground water surface. • Low TPH and benzene concentrations were detected in the first sampling event, but these concentrations were not consistently detected in the second sampling event (including the laboratory retained by San Joaquin County). Concentrations were not detected during the third sampling round conducted by Kleinfelder. Concentrations detected during the first round of sampling may have been induced during the drilling and construction of the well. FR1-92-15 Page 19 of 21 Copyright 1992 Meinfelder, Inc.