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12 March 1999 i AGE-NC Project No 97-0333 Page 2 of 6 collected from the floor of the excavation and beneath product piping Total pets oleum hydrocarbons quantified as gasoline (TPH-g) were detected beneath the east ends of the three USTs at concentrations ranging to 2,600 milligrams per kilogram(mg/kg),beneath the west ends of the USTs at concentrations ranging to 25 mg/kg,and beneath product piping at concentrations ranging to 8,000 mg/kg Volatile aromatics (benzene,toluene, ethylbenzene and xylenes BTEX) were detected beneath the east ends of three USTs at concentrations ranging to 340 mg/kg, beneath the west ends of the USTs at concentrations ranging to 2 7 mg/kg, and beneath product piping at concentrations ranging to 880 mg/kg Fuel oxygenates (methyl tertiary butyl ether MTBE, tert-amyl methyl ether TAME and tert-- butanol TBA) were detected beneath the east ends of the three USTs at concentrations ranging to 16 mg/kg, beneath the west ends of the USTs at concentrations ranging to 3 1 mg/kg, and beneath product piping at concentrations ranging to 690 mg/kg 23 REGIONAL GEOLOGIC SETTING 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 fat- 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 The northern and southern portions of the Great Valley Province have been designated the Sacramento and San Joaquin Valleys, respectively Based on the General Soil Map from the San Joaquin County Soil Survey, published by the United States Department of Agnculture Soil Conservation Service in 1992,the site area is within the Delhi- Ventas-Tinrun (DVT) association The DVT soils are located within dunes, alluvial fans and stream terraces along the Stanislaus River, and generally consist of well drained coarse textured soils The soils are generally derived from both marine and non-manne sediment, and are generally formed in alluvium denved from granitic and mixed rock sources 24 GROUND WATER DEPTH AND FLOW DIRECTION The estimated depth to ground water at the site is between 15 and 20 feet below surface grade (bsg) Advanced GeoEmkronmentai,Inc