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t 04 August 2006 AGE-NC Project No. 95-0137 Page 2 of 4 1.2. 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). The estimated depth to ground water at the site is approximately 20 feet-.71-iz below surface grade (bsg) based on data from the on-site monitoring wells. The ground water flow is generally toward the west to northwest. 2.0. SCOPE OF WORK AGE proposes to collect grab ground water samples to determine if petroleum hydrocarbon-and/or 1,2-DCA-impacted ground water is present off-site, west of Highway 99. The site assessment will include the following tasks: • Permitting and pre-field work activities; • Soil sample collection and analysis; and • Report preparation. The preliminary site assessment tasks are discussed below. Advanced GeoEnvironmental,Inc.