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14 June 2004 AGE-NC Project No. 04-1180 Page 2 of 5 2.3. 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. 1� 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. PROCEDURES The field work reported herein was performed in accordance with procedures outlined in the AGE-prepared Limited Subsurface Investigation Work Plan, dated 25 May 2004, and approved by the San Joaquin County Environmental Health Department(SJCEHD).A boring permit and permit fee were submitted to the SJCEHD prior to implementation of field work. A copy of the approved permit is included as Appendix C. 3.1. DRILLING On 01 June 2004, two soil probe borings (P 1 and P2)were advanced at the site to collect soil and ground water samples as part of the assessment activities. Each boring was advanced to 50 feet below surface grade(bsg)using"direct push"technology,utilizing a truck-mounted Geoprobe 5400 r Advanced GeoEnvironmental,Inc. ..r