Laserfiche WebLink
17 April 2002 <br /> AGE-NC Project No. 01-0872 <br /> Page 2 of 6 <br /> • Lead was detected in the soil samples collected beneath UST TA3 and from one sample collected <br /> beneath the product lines(T4-3.5) at concentrations as high as 11 mg/kg, which is within the range <br /> of natural lead concentrations in California soils. <br /> k. <br /> 2.2. REGIONAL GEOLOGIC/HYDROGEOLOGIC SETTING <br /> �. The site is located within the northern San Joaquin Valley which comprises part of the Great Valley <br /> geomorphic province of California. The San Joaquin Valley is formed by the Great Valley <br /> geosyncline,which is a large, elongate,northwest-trending asymmetrical structural trough(basin). <br /> It is bordered by the Coast Ranges to the west, the Klamath Mountains and Cascade Range to the <br /> north, and the Sierra Nevada to the east. This trough has been filled with sediments derived from <br /> both marine and continental sources. Thickness of the sedimentary fill ranges from thin veneers <br /> along the valley edges to more than 20,000 feet in the south central portion of the valley; the older <br /> f sedimentary deposits are primarily marine in origin and the younger deposits are primarily <br /> continental. Continental-derived sediments were primarily deposited in lacustrine, fluvial, and <br /> alluvial environments;the main sediment sources were the mountain ranges surrounding the valley <br /> (Olmsted and Davis, 1961). The site is located on unconsolidated and semi-consolidated alluvium, <br /> lake,playa and terrace deposits of Quaternary age(California Division of Mines and Geology, 1977). <br /> The Modesto, Riverbank and Turlock Lake Formations and overlying Recent alluvium are the <br /> principal sources of domestic ground water in the 13,500-square mile San Joaquin Valley Ground <br /> Water Basin(Basin 5-22). <br /> 2.3. GROUND WATER DEPTH AND FLOW DIRECTION <br /> Based on information obtained during drilling,ground water depth beneath the site is approximately <br /> 25 to 30 feet below surface grade(bsg). Based upon data obtained from nearby sites, the prevailing <br /> ground water flow direction in the vicinity of the site is estimated to be north-northeast. However, <br /> r- flow direction may vary both locally and seasonally. <br /> 3.0. PROCEDURES <br /> On 05 March 2002, three soil borings (B1, B2 and 133) were advanced at the site as part of the <br /> assessment related to the former USTs. The field work was conducted as outlined in the <br /> AGE-prepared Preliminary Site Assessment Work Plan, dated 19 September 2001. <br /> rr <br /> 1r Advanced GeoEnvironmentai,Inc. <br /> 1.r <br />