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feet bsg, and 165 to 170 feet bsg Monitoring wells MW-4 and MW-5 were constructed with a fifth screened interval from approximately 193 feet bsg to 198 feet bsg ' A total of 28 soil samples were analyzed The highest concentrations of petroleum hydrocarbon compounds were detected from soil samples collected at between 40 and 60 feet bsg, in HU-1 ' Middle Zone TPH-g was detected in soil samples collected from soil borings MW-4,MW-5 and B-2 at concentrations as high as 4,500 milligrams per kilogram (mg/kg) (MW4-58), 3,600 mg/kg (MW5-50) and 2,000 mg/kg (B2-50) ' The BTEX samples compound benzene was detected in soil les collected from MW-4,MW-5 and B-2 P p ' at maximum concentrations of 33 mg/kg (MW4-58), 21 mg/kg (MW5-50) and 20 mg/kg (B2-50), toluene was detected at maximum concentrations of 180 mg/kg(MW4-58), 100 mg/kg(MW5--50) and 54 mg/kg (B2-50), ethylbenzene was detected at maximum concentrations of 19 5 mg/kg ' (MW4-58), 30 mg/kg (MW5-50) and 13 mg/kg (B2-50), and total xylenes were detected at maximum concentrations of 224 mg/kg (MW4-58), 182 mg/kg(MW5-50) and 77 mg/kg(B2-50) ' Fuel additives including DIPE,ETBE,MTBE, TAME,TBA,EDB and 1,2-DCA were not detected in the soil samples collected and analyzed from the three soil bonngs Additional VOCs detected in the analyzed samples included isopropylbenzene, n-propylbenzene,1,3,5-tnmethylbenzene, 1,2,4- ' tnmethylbenzene p-isopropyl-toluene and naphthalene REGIONAL GEOLOGIC SETTING According to the Geologic Map of California, published in 1977 by the State of California Department of Mmes and Geology, the site area is within the Great Valley Geomorphic Province of California, a large, elongate, northwest trending structural trough The Great Valley Province has been filled to its present elevation with thick sequences of sediment ranging in age from Jurassic to 1 present day, 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 Mountains, respectively The Great Valley Province is subdivided into two major divisions designated the Sacramento and San Joaquin Valleys ' Based on the General Soil Map from the San Joaquin County Soil Survey, published by the United States Department of Agriculture Soil Conservation Service in 1992, the site area is within the ' Jacktone-Hollenbeck-Stockton (JHS) association The JHS soils are located within basins, and generally consist of moderate to poorly drained fine textured soils The soils are generally derived from both marine and non-manne sediment, and are generally formed in alluvium derived from mixed rock sources GROUND WATER DEPTH AND GRADIENT According to the map titled Lines Of Equal Depth Of Water Wells-Fall 1996, published by the San Joaquin County Flood Control and Water Conservation District,the estimated depth to ground water