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20 August 1998 AGE-NC Project No. 98-0483 Page 2 of 5 TPH-d was detected in one soil sample at 14,000 parts per million(ppm,reported as milligrams per kilogram or mg/kg); TPH-mo was detected in seven samples at concentrations as high as 14,000 ppm; total xylenes were detected in two samples at concentrations of 6.0 and 12 parts per billion (ppb,reported as micrograms per kilogram orµg/kg). Benzene,toluene and ethylbenzene were not detected in any of the soil samples analyzed. After removal of the USTs and sampling,the excavation was backfilled to surface grade with clean fill material. 2.3. REGIONAL GEOLOGIC SETTING The site is located in the eastern portion of the Great Valley geomorphic province of California. The valley is a nearly flat,elongate trough trending northwest and southeast for approximately 450 miles. The valley is enclosed by the granitic Sierra Nevada on the .east and the sedimentary and metamorphic Coast Ranges on the west. The surficial and upper several hundred feet of subsurface layers consist primarily of unconsolidated alluvial and flood plain deposits(predominantly sand,silt, and clay)of Quaternary age,which were derived from the mountains of the Sierra Nevada. Beneath the upper sedimentary deposits lie a thick sequence of marine deposits of Mesozoic age,which in, turn are underlain by a pre-Jurassic complex of igneous and metamorphic basement rock. - 2.4. GROUND WATER DEPTH AND FLOW DIRECTION The estimated depth to ground water at the site is between 60 and 70 feet below surface grade(bsg) based on information from Lines of Equal Depth of Water Wells Fall 1996, published by the San Joaquin County Flood Control District and Water Conservation District. However, with significant ground water recharge between 1994 and 1996, ground water depth at the site may have deceased to 40 feet bsg. Based upon data obtained from nearby sites,the prevailing ground water flow direction is estimated to be southeast at the American Transfer Company site. However, flow directions may be both locally and seasonably variable. The uppermost ground water flows in an unconfined aquifer. With increasing depth,the aquifer becomes semi-confined, due to the presence of mixed heterogeneous layers of sediments. Duck Creek is the nearest surface water to the property, located approximately 750 feet south of the site.Duck creek usually contains little water and is not likely to have a significant effect upon ground water depth or flow direction in the area. Advanced GeoEnvironmental,Inc.