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16 October 2009 AGE-NC Project No. 09-1714 Page 2 of 5 The scope of work included advancement of nineteen soil borings,for collection and analysis of soil samples, in the area of the Agricultural and Natural Resources Yard/Shima Center at SJDC, 5151 Pacific Avenue, Stockton, California. REGIONAL GEOLOGIC/HYDROGEOLOGIC SETTING The site is situated within the southern portion of the Great Valley Geomorphic Province of California, a large, elongate, northwest trending, asymmetric structural trough; the northern and southern portions of the Province have been designated the Sacramento and San Joaquin Valleys, The Province is bordered by the Coast Ranges to the west, the Klamath Mountains and Cascade Range to the north, and the Sierra Nevada to the east. The Great Valley has been filled with sediments derived from both marine and continental sources. Thickness of the sedimentary fill ranges from thin veneers along the valley edges to more than 20,000 feet in the south central portion of the valley.The sedimentary formations range in age from Jurassic to Recent,with the older deposits being primarily marine in origin and the younger deposits being primarily continental. Continental-derived sediments were primarily deposited in lacustrine, fluvial,and alluvial environments with sediment sources being the mountain ranges surrounding the valley(Olmsted and Davis, 1961);the site itself is located on unconsolidated and semi-consolidated alluvium, lake, playa and terrace deposits of Quaternary age (California Division of Mines and Geology, 1977).Rocks composing the basement complex of the Province have not been completely defined but are believed to be metamorphic and igneous in origin. The Modesto, Riverbank and Turlock Lake Formations and overlying Recent alluvium are the principal sources of domestic ground water in the 13,500-square mile San Joaquin Valley Ground Water Basin(Basin 5-22). The estimated depth to ground water at the site is approximately 50 feet below surface grade (bsg) based on information from Lines of Equal Depth of Water Wells Fall 1999,published by the San Joaquin County Flood Control District and Water Conservation District- FCD&WCD. Based on the map titled Lines of Equal Elevation of Groundwater Spring 1999 also published by the San Joaquin County FCD&WCD, the local ground water elevation is generally toward the east. However,this may be greatly modified by local recharge and discharge patterns. PREVIOUS ENVIRONMENTAL INVESTIGATIONS In May 1995,one 2,000-gallon underground storage tank(UST),two 10,000-gallon USTs and one 500-gallon UST were removed from the site. The USTs were reportedly used for storage of waste oil associated with the adjacent shop,diesel fuel and leaded gasoline.At the time of the removal,all Advanced GeoEnvironmental,Inc.