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IBank of Stockton Page 5 Groundwater Monitoring Report ' Project No. 358.2 December 20, 1995 detected was a result of trace amounts of crank case oil drips working into the ' well. On December 7, 1995, all well caps and locks were replaced with new ones. DW-1 The domestic water well located on the Cutter Lumber facility (herein called DW-1) is located several hundred feet north of the release site of the Western Lift facility. The sample collected on November 29, 1995 was found to contain significant levels of petroleum hydrocarbons and VOCs. As shown in Table 2, ' 624 ppb of gasoline -range petroleum hydrocarbons were detected as was 206 ppb benzene as well as other VOCs. Insofar as this result was not anticipated, it was decided to re-sample the well. First, however, immediately after receiving the lab results, Geological Technics personnel contacted Cutter Lumber, informed them of the nature of the ' contamination, and advised that Cutter personnel not use the well for drinking or washing. The following morning, a Cutter representative called to advise Geological Technics that the well has not been used for any purpose. On December 7, 1995, Del-Tech Geotechnical Support personnel arrived at the location, to re-sample the well. The pump was activated, and the well was flowed for more than 30 minutes, and then collected a water sample for analysis. The results of this data indicate there was no detectable petroleum hydrocarbons ' in the well water but that low levels of VOC remained. There was 6 .ppb benzene and 0.8 ppb ethylbenzene in the sample. . ' 4.0 CONCLUSIONS The following conclusions have been drawn regarding this quarterly ' groundwater sampling event: • The direct4on of groundwater flow and gradient are consistent with prior monitoring events as reported by Geological Audit Services. • Low levels of VOCs continue to persist in monitoring wells MW-1 and MW-4. ' • Oil range petroleum hydrocarbons detected in MW-5 may be a result of motor oil from vehicles contaminating the well, which is located in a parking lot.