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11 August 2004 - AGE-NC Project No. 04=1180 Page 2 of 8 concentrations of contaminants detected in sample P1-W did not justify placement of the site into the Local Oversight Program (LOP): _ 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). The estimated depth to ground water at the site is approximately 30 to 40 feet below surface grade based on information from surrounding sites monitored by AGE.However, this may be greatly modified by local recharge and discharge patterns. 3.0. SCOPE OF WORK At the request of the entities involved in the property transfer of the site,AGE proposes to drill and install one ground water monitoring well approximately 30-feet northeast(inferred down-gradient direction)of boring P 1 (June 2004). The monitoring well installation and sampling will include the following tasks: • Permitting and pre-field work activities; • Drilling and completion of the monitoring well; Advanced GeoEnvironmental,Inc.