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24 July 1997 AGE-NC Project No. 97-0349 Page 2of5 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 floodplain 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 50 feet below surface grade (bsg) based on information from Lines of Equal Depth of Water Wells Fall 1993, published by the San Joaquin County Flood Control District and Water Conservation ,District and ground water depth measurements in monitoring wells located approximately 400 feet north and 200 feet south of the site (Re-Manufacturing). Ground water flow direction, as determined from the Re-Manufacturing site, is south-southeast. However,due to seasonal variations in ground water depth, flow direction may vary. 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. 3.0. SCOPE OF WORK The scope of work includes the collection and analysis of subsurface soil samples from the former UST area. AGE proposes to collect soil samples using direct push technology (DPT). Initially, one soil probe boring will be advanced within the former UST excavation; the probe boring will be advanced to a depth of approximately 50 feet or until groundwater is encountered. If necessary, additional soil probe borings will be advanced to adequately characterize the lateral and vertical extent of hydrocarbon-impacted soil. 3.1. PROBING AND SAMPLING Soil probe borings will be advanced using a Geoprobe 5400 soil probing unit equipped with 1.125- inch diameter probe rods and an attached 2.15-inch diameter soil sampler. The initial probe boring Advanced GeoEnvironmental,Inc.