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ME <br /> WE <br /> KIN <br /> i <br /> IIMI <br /> .4e- <br /> During well installation, soil samples were collected from <br /> Mw--6 and MW--8 immediately above the water table, at a depth <br /> of 3 feet below grade. There was no visual evidence of <br /> gasoline contamination in the soil cuttings obtained during <br /> drilling. The total petroleum hydrocarbon concentrations <br /> detected in the soil samples from MW-6 and MW-7 were 1.8 <br /> and 24.0 ppm, respectively. <br /> The four additional wells (Mw-5 to MW-R) were developed <br /> and sampled in February 1987. No free product or sheen <br /> was noted in any of the samples. Analysis of the ground <br /> water samples from the four monitoring wells showed <br /> detectable levels of total petroleum hydrocarbons ranging <br /> from 6.3 to 41.0 ppm (Kaprealian, 1987) . <br /> 2.2.4 Ground water Monitoring and Sampling <br /> The eight existing ground water monitoring wells were <br /> sampled on a monthly basis beginning in September 1987. <br /> Results of ground water level monitoring are presented in <br /> Table 1, while the results of ground water analysis are <br /> presented in Table 2. Free-floating product was <br /> subsequently observed in MW-3, while dissolved gasoline <br /> continuously detected in five of the <br /> _ constituents were y <br /> wells (MW-4 to MW-8) . The last sampling event performed by <br /> KEI was in October 1988. <br /> --� 2.3 Regional l Geology Ind H\drggeology J <br /> The following description of regional geology with respect to <br /> the site wag based on the United States Geological Survey <br /> Professional Paper 1401-C (1986) . <br /> The site lies in the Central Valley of California, which is <br /> ' about 400 miles long and averages about 50 miles wide, <br /> encompassing about 20,000 square Miles. Geologically, the <br /> valley is a large asymetric trough that is bounded by <br /> -- granitic, metamorphic, and marine sedimentary rocks of <br /> pre-Tertiary age. The trough has been filled with as much as <br /> 30,000 feet of sediment in the San Joaquin Valley to the <br /> south and as much as 60,000 feet of sediment in the <br /> Sacramento Valley to the north. These sediments range in age <br /> from Jurassic to Holocene and include both marine and <br /> continental rocks and sedimentary deposits. <br /> The scope of this investigation includes only the uppermost <br /> deposits within the Central Valley. Continental rocks and <br /> deposits of Tertiary and Quaternary age compose a number of <br /> formations; in total they constiLute the major aquifer of the <br /> Central Valley-and-yield--large-quantities of-water-to <br /> --wells.-- - --- <br /> Lithologically these deposits are heterogenous mixtures of <br /> 4 <br />