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r 26 September 1997 AGE-NC Project No 97-0330 rPage 2 of 7 r been filled to its present elevation with thick sequences of sediment ranging in age from Jurassic to 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 r are comprised of the California Coast Range and the Sierra Nevada, respectively The Great Valley Province is subdivided into two mayor divisions designated the Sacramento and San Joaquin Valleys r 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 rgenerally consist of moderate to poorly drained, fine textured soils The soils are generally derived from both marine and non-marine sediment, and are generally formed in alluvium derived from mixed rock sources r r2 3 GROUND WATER DEPTH AND GRADIENT According to the map titled Lines Of Equal Depth To Groundwater - Spring 1996, published by the San Joaquin County Flood Control and Water Conservation District, the estimated depth to ground water at the property is between 50 and 60 feet bsg Prevailing ground water flow direction in eastern Stockton is generally toward the northeast, although flow directions may vary locally and seasonably r 3 0. PROCEDURES 3 1 SCOPE OF WORK ' The scope of work for this investigation was to test for and assess petroleum hydrocarbon impact beneath the underground storage tank (UST) and dispenser island area at the site The scope of work for this site assessment included advancement of two soil borings, collection of both soil and ground ' water samples for laboratory analysis, and preparation of this report ' 3 2 ADVANCEMENT OF SOIL BORINGS On 02 September 1997, two soil borings(P-3 and P-4) were advanced vertically to depths of 65 feet bsg near the former UST and dispenser island area at the site Advancement of soil borings was accomplished utilizing a CME-75 truck-mounted drill rig equipped with 8-inch diameter, hollow stem augers Soil cuttings generated during drilling activities were stockpiled on plastic sheeting in an area lacking public access at the site Soil boring P-3, and the earlier soil boring P-2, were advanced in the reported former area of a product line The locations of soil borings P-3 and P-4 are depicted on Advanced GeoEnviroiunental,Inc r