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05 January 2009 AGE-NC Project No. 09-1664 Page 2 of 6 2.2. 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, respectively.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). 2.3. GROUND WATER DEPTH AND FLOW DIRECTION Based on data obtained from a nearby site (800 Main Street, Stockton, California) the depth to ground water at the site is approximately 30 to 35 feet bsg. The prevailing ground water flow direction in the vicinity of the site is estimated to be toward the east-northeast. However, flow direction may be both locally and seasonably variable. 3.0. SCOPE OF WORK The analytical results from the UST removal soil samples indicate that an unauthorized release of petroleum hydrocarbon compounds from the former UST has occurred at the site.AGE proposes to advance twos &borings to collect soil and an in-situ grab ground water sample to assess the extent of petroleum hydrocarbon impact to soil and ground water beneath the site. The preliminary site assessment will consist of the following tasks: .Wraad Ge EavirowealaL rac