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771 <br /> -14 August 2000 <br /> AGE-NC'Proj ect No. 98=0492 j <br /> Page 3.of 8 <br /> concentration of 4.5 µg/1 in the ground water sample ollected from probe boring P-2. No other <br /> I nalytes were detected above laboratory reporting limits i�the.groundwater sample analysis.Results <br /> of the investigation can be found on Table 2. <br /> 2.4. REGIONAL GEOLOGIC/HYDROGOLOGId SETTING <br /> The site is located within the southern San Joaquin Valley which comprises part of the Great Valley <br /> geomorphic province of California. The-San Joaquiii 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 Kl*ath Mountains and Cascade Range to the <br /> north;'and the Sierra Nevada to the east. This trough h4s been'filled with sediments derived.from . <br /> both marine .and continental sources. Thickness of the I sedimentary fill-ranges from thin veneers <br /> along the valley edges to more than 20,000 feet in,thsouth central portion of the valley. The <br /> sedimentary formations range in age with theA older depo its being primarily marine in origin and the <br /> younger deposits being primarily continental. Contifrental-derived sediments were primarily <br /> deposited in lacustrine,fluvial, and alluvial environment -with sediment sources being the mountain <br /> ranges surrounding the valley(Olinsted and Davis, 1961.. The site is located on unconsolidated and . <br /> semi-consolidated alluvium, lake playa and terrace.depoisits of Quaternary age (California Division <br /> 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 13,5 0-square mile San Joaquin Valley Ground <br /> Water Basin (Basin 5-22). <br /> 2.5, GROUND WATER DEPTH-AND FLOW DIR�CTION . <br /> Based on information obtained from anearby site and prvious investigations by AGE,ground water <br /> depth in the vicinity of the site is approximately 15 to 20 feet bs&The prevailing ground water flow <br /> direction in the vicinityof the site is inferred to be towar the northwest to north-northeast.However, <br /> flow direction maybe both locally and seasonably van ble. <br /> 3.0. SCOPE OF WORK <br /> Based.ori the results of the UST removal soil sampli�g, an.unauthorized.release of petroleum <br /> hydrocarbon compounds from the fuel USTs has been,dgtermimd to have occurred at the site. AGE <br /> proposes to collect soil samples and in-situ grab grouid.water samples to assess the lateral and <br /> Advanced GeoEnvironmental,Inc.- <br />