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KLEINFELDER 4 CONCLUSIONS Based on the field and analytical results of the preliminary soil assessment investigation, TPH as diesel from the underground tanks and/or associated piping are present in the soil adjacent to the west edge of the previous tank excavation. TPH as diesel were detected in B-4 adjacent to the west edge of the tank excavation at 9 feet below the surface. This result corresponds with California Water Labs result of 4,400 ppm for Sample P-69750 collected at a depth of roughly 8 feet, approximately 4 feet '-' northeast of B-4. California Water Labs reported the original sample as motor oil. Verbal communication with Mr. Chris Harvey, the analyzing chemist at California Water Labs, ,., indicated that their analysis was nun over a wide boiling point range in order to examine constituents from gasoline to motor oil. Mr. Harvey stated that peaks were present in the diesel range, but the main peaks were in the motor oil range, indicating a predominance of motor oil, not diesel fuel, in the sample. Mr. Harvey also stated that it was quite possible that the compounds detected in the oil range were weathered constituents of diesel. Dan Bilbrey, the director of general services for Tracy Community Memorial Hospital, indicated that the tanks were used for diesel fuel, and the presence of a diesel pump +� approximately 20 feet south of the excavation indicates that the tanks were probably used for diesel and not oil. The low TPH value of 14 ppm from B-7 at a depth of 13 feet, could represent the westward edge of contamination. The lack of contamination in B-1 through B-3, B-5, and B-6 suggests that the lateral extent of contamination is probably limited to the western edge of the previous excavation. The cause of the contamination may have been from one of the tanks, piping, vent lines, poor tank filling practices, or any combination. '-' A preliminary assessment of the presence and concentration of TPH contamination indicates that contamination is present immediately adjacent to the west edge of the �. original excavation. Soil with a TPH concentration of over 100 mg/kg may require future remediation. TPH concentrations allowed to remain in the soil generally range from 0 to LM 100 mg/kg depending on the local lithology and regulatory agencies. TPH concentrations over 1,000 ppm are generally considered hazardous waste. One sample from B-4 (Sample 21909) had a concentration of 3,000 mg/kg. j 150-88-2193 6