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• SS No. 6348, Tracy <br /> PIER, 1/31/92 <br /> Complete results of laboratory analyses are shown in <br /> Table 2 . These show that MW-1 and MW-2 soil and water were Non <br /> Detect for all components tested. MW-•3 was Non Detect for all <br /> components in the soil, but showed low levels of TPHg and BTEX <br /> in water. MW--4 initially showed low levels of TPHg and BTEX in <br /> the water sample, but two subsequent samples were Non Detect. <br /> There was no contamination found in soil samples taken during <br /> the drilling of MW--4 . <br /> All borings which were not converted into monitoring <br /> wells (B-1 through B-12) were Non Detect for all substances <br /> analyzed , with the following exceptions : TPHg and BTEX <br /> contamination was identified in B-1 at the 8 . 0 foot depth, B-7 <br /> at the 3 . 5 foot depth, B-9 at the 9 . 5 foot depth, and B-10 at <br /> both the 5 .5 foot and the 9 . 5 foot depth. <br /> Oil and grease contamination was found at B-1, B-6, <br /> and B-9 at shallow depth. Of these, the B--6 sample was analyzed <br /> for solvents and metals and had no significant amounts of these <br /> components. <br /> As required by San Joaquin County for wells within 50 <br /> feet of a sewer , wells were checked for fecal coliform <br /> bacteria. The grounwater from all four wells were reported to <br /> contain less than the 3 per gram detection limit. <br /> Laboratory reports and Chain--of-Custody documentation <br /> can be found in Appendix C. <br /> GEOLOGY AND HYDROGEOLOGY <br /> The subject property is situated on a relatively <br /> level lot in low terrain gently grading toward the San Joaquin <br /> Delta to the north. The site is located in the Central Valley <br /> geomorphic province of California, an area underlain by a thick <br /> sequence of continental and marine sediments ranging in age <br /> from Recent to pre-Cretaceous (Calif. Dept. of Water Resources <br /> Bull. 146, 1967) . <br /> The late Tertiary to Recent sediments which comprise <br /> the uppermost sequence underlying the area of the subject site <br /> consist primarily of continental deposits derived from hills to <br /> the southwest. These, 1n turn, have been overlain by fluvial <br /> and lacustrine clays and silts. <br /> As exposed in the borings , the sediments at this <br />