SITE INFORMATION AND CORRESPONDENCE

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8720019-1 CON-4 i The results of these analyses are given in Table 1 and discussed below. Copies of the lab reports are appended to this report. RESULTS The field screening and observations made during the excavation indicated that the large majority of the contaminated soil had been removed, and only minor amounts of lightly contaminated material remained. These observations were substantiated by the laboratory results which indicated that only samples E-2 and E-4 contained hydrocarbons above the detection limit. The analysis of sample E-2, which was taken from the aforementioned area adjacent to well MW-17, found a TPH level of 31 mg/kg, as well as low levels of aromatics. Sample- E-4 was found to contain TPH at the detection level of 10 mg/kg with no detectable BTEX. In either case, the concentration of hydrocarbons is low. The total lead concentrations were also low, ranging from 6 to 14 mg/kg and assumed to be naturally occurring background levels. As with the excavation samples, the composite samples of the excavated material were also found to contain relatively low TPH levels of 21, 16 and 31 mg/kg for C-2, C-2 and C-3, respectively. The lead levels were between 10 and 11 mg/kg and again assumed to be naturally occurring. Based on the above TPH levels and a San Joaquin County Air Pollution District internal memo dated October 16, 1986, declaring any material with less than 50 mg/kg organics to be exempt from aeration restrictions, the plastic was removed from the spoils pile and the material allowed to aerate. The results of the analyses of the May 19 water samples from wells MW-17 and MW-18 were suspect as they indicated a TPH concentration of 3.2 mg/L for MW-18 and nondetectable for MW-17. This is contrary to the analysis of samples taken following well installation in November 1986. At that time no detectable hydrocarbons were found in MW-18 and MW-17 levels were similar to those found currently in MW-18. In addition, observations made -6-