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' 28 August 2000 AGE-NC Project No 97-0249 ' Page 2 of 10 ' detected at concentrations as lugh as 7,100 mg/kg, and BTEX were detected at concentrations up to 180 mg/kg(xylenes,P2 at 20 feet) Results of the September 1997 investigation were reported in the Preliminary Investigation and Evaluation Report (PIER) dated 05 November 1997 and the Site ' Assessment Report dated 27 October 1998, both prepared by AGE ' 2 3 REGIONAL GEOLOGIC SETTING According to a Geologic Map of California, published in 1966 by the California Department of Conservation Division of Mines and Geology, the site area is within the Great Valley Geomorphic Province(GVGP)of California, a large, elongate,northwest trending structural trough The GVGP ' is subdivided into two major divisions designated the Sacramento and San Joaquin Valleys, which have been filled to the present elevation with thick sequences of sedunent 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 are comprised of the California Coast Range and the Sierra Nevada, respectively Based on a General Soil Map from the San Joaquin County Soil Survey, published by the United lie States Department of Agriculture Soil Conservation Service in 1992, the site area is described as within the Guard-Devnes-Riblancho (GDR) association The GDR soils are located within basin rims along the eastern edge of the Sacramento-San Joaquin Delta area, and generally consist of poorly drained, fine to coarse textured soils The GDR soils generally formed in alluvium from mixed rock sources 2 4 GROUND WATER DEPTH AND GRADIENT According to the map titled Lanes Of Equal Depth To Groundwater-Spring 1996, published by the San Joaquin County Flood Control and Water Conservation District(SJCFCWCD), the estimated , depth to ground water at the property is between 10 and 15 feet below surface grade (bsg) According to the map titled Lines of Equal Elevation of Ground Water-Spring 1996,also published by the SJCFCWCD, the prevailing ground water flow near the site is generally toward the south- southwest, although flow directions may vary locally and seasonably ' Review of ground water monitoring well data located approximately 500 feet east of the site indicated that historical ground water gradient flowed in a southerly direction,while seasonal high Iand low depth to ground water ranged between 3 and 14 feet beneath surface grade Rdiwneed GcaEnnrenmenW,Inc I