SITE INFORMATION AND CORRESPONDENCE

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� y i then driving a six inch brass sleeve into the soil that had been collected in the bucket. The brass sleeve was sealed with Teflon tape and plastic caps, labeled, and placed in a secured, iced cooler for transportation. A single sample was also obtained from the excavated soil for characterization. Each soil sample was screened in the field with a flame-ioniation detector (FID) to assess the presence of volatile organics in parts per million by volume (ppmv), No FID readings were recorded for the excavation confirmation samples. FID readings ranged from 1 to 2 ppmv in the stockpile soil. Additionally, no soil discoloration or odor was observed in the excavation confirmation samples. The soil samples were transported under chain of custody protocol to Superior Analytical Laboratory. h Analytical Results The excavation and stockpile samples were analyzed for total petroleum hydrocarbons (diesel- heavy oil range) using EPA method 8015. BTEX was not included in the confirmation analysis, because it was not detected in the original boring investigation (include the sample with 11,000 mg/kg TPH). The four sidewall samples did not contain TPH concentrations above the laboratory reporting limit. The excavation bottom sample and the stockpile sample both contained 51 mg/kg total petroleum hydrocarbons. The sample depths and results are summerized on Table 1. The laboratory data sheets and chain of custody are attached. Conclusions Approximately 25 cubic yards of soil contaminated with fuel oil were excavated and stockpiled on site. Confirmation samples indicate that the bulk of the contaminated soil has been removed. The sidewall samples were non-detect indicating the lateral extent of contamination. The excavation bottom sample was 51 mg/kg, which is a significant reduction from the 11,000 mg/kg detected in boring B-4. BTEX contaminants were not detected in the previous boring investigation and are not a concern at the site. j 4 Given the results of the initial boring assessment which indicated that contamination was not present beyond a depth of 11 feet; the limited volume of soil removed from the excavation; the significant reduction of TPH concentrations; the lack of BTEX contamination; and a depth to groundwater of 30 to 35 feet, Kleinfelder does not recommend additional assessment or additional excavation at this time. The low concentration of TPH remaining at the bottom of the excavation will degrade naturally over time. It is Kleinfelder's understanding that O'Brien-Krietzer has taken the 25 cubic yards of soil removed to an on-site area, and TPH in the stockpile soil will be allowed to degrade naturally over time. A copy of this report should be submitted to San Joaquin County Public Health Services Environmental Division for their' review and approval prior to proceeding with further construction or activities at the site. I i ,i 24-220152-FOO/CR32-1 (1994) Page 2 of 3 January 13, 1994 Copyright 1994 Kleinfelder, Inc. KLEINFELDER 3077 Fite Circle, 5acrawentn, CA 95827 (9161 306-1701 -