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a � L 20 July 2000 AGE Project No. 98-0456 Page 2 of 7 used to collect a soil sample from 3 feet below the end of the former UST. A soil sample was also collected from the soil stockpile. The soil removed to uncover the tank was replaced and compacted back into the UST excavation. �. TPH-g was present in both samples analyzed at concentrations as high as 250 milligrams per kilogram (mg/kg). TPH-d was present in both samples analyzed at concentrations as high as 3,500 mg/kg. BTEX compounds were present in both samples analyzed at concentrations as high as 10 >`. mg/kg. Fuel additives were not detected in the soil samples. Chlorinated hydrocarbons were detected in both soil samples analyzed. The compounds trichloroethene (TCE) and tetrachloroethene (PCE) were detected in both of the soil samples at concentrations as high as 220 micrograms per kilogram (4g/kg). Other solvents and chlorinated compounds were detected in both of the soil samples. Polycholorinated biphenyls (PCBs)PCE were Ia detected in the soil sample collected from beneath the invert of a former UST at a concentration of 3,500 Ag/kg. A summary of soil analytical results were previously presented or shown in Table 1. w 2.3. REGIONAL GEOLOGIC SETTING Le The property is situated within the Great Valley Geomorphic Province of California, a large, elongate, northwest trending, asymmetric structural trough. The Great Valley Province has been filled with thick sequences of sediment ranging in age from Jurassic to Recent, creating a nearly flat- lying alluvial plain, extending from the Tehachapi Mountains in the south to the Klamath Mountains �.. in the north. The western and eastern boundaries of this province are comprised of the California Coast Range and the Sierra Nevada, respectively. Rocks composing the basement complex of the province have not been completely defined but are believed to be metamorphic and igneous in origin. Ir The northern and southern portions of the Great Valley Province have been designated the Sacramento and San Joaquin Valleys, respectively. �. The Modesto, Riverbank, Turlock Lake Formations and overlying recent alluvium are the principal source of domestic ground water in the 13,500-square-mile San Joaquin Valley Ground Water Basin (Basin 5-22). This basin is drained primarily by the San Joaquin River. LM 2.4. GROUND WATER DEPTH AND GRADIENT Le Based on review of the Lines of Equal Depth to Groundwater Fall 1997 map published by the San Joaquin County Flood Control District and Water Conservation District(FCD&WCD),the estimated depth to ground water at the site is 50 feet below surface grade (bsg). Based on the map Lines of Advanced GeoEnviron mental,Inc.