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r) tiU <br /> Supplemental Investigation Report <br /> BP Oil Site No 11193 <br /> C A M B R I A Stockton, California <br /> October 13, 2000 <br /> Drilling Method 8-mch diameter hollow stern augers were used for the installation of wells <br /> MW-9 and MW-10 10-inch diameter hollow stem augers were used for <br /> the destruction of well MW-2 and the installation of wells MW-1R and <br /> MW-2R Well MW-8 was initially sampling using 8-inch diameter <br /> hollow stem augers, and over drilled with 10-inch diameter hollow stem <br /> augers for well installation <br /> Sampling Method Wells MW-1R,MW-9 and MW-10 were sampled at 5-foot intervals using <br /> a modified California split spoon sampler, well MW-8 was continuously <br /> Mr Ago,3M <br /> cored using a Moss sampler <br /> Boring Depths Wells MW-1R, MW-9 and MW-10 were advanced to 315 feet bgs,well <br /> MW-2R was advanced to 30 feet bgs, and well MW-8 was advanced to <br /> 50 feet bgs <br /> Groundwater Depths During drilling, groundwater was first-encountered at between <br /> approximately 11 feet and 14 feet bgs On July 14, 2000, the static depth <br /> to water in the new wells was between 11 and 12 5 feet bgs(see Table 1) <br /> Soil Types Encountered Soils encountered consisted of silty sands and/or sands to the total depth <br /> explored of 50 feet bgs (see Appendix D) <br /> Chemical Analysts Selected soil samples were analyzed for TPHg using modified EPA <br /> Method 8015, and benzene, toluene, ethylbenzene, xylenes(BTEX)and <br /> MTBE using EPA Method 8260 by Pace Analytical Services, Inc of <br /> Long Beach, California (Pace) (see Table 2) Analytical results are <br /> summarized on Table 2 and presented in Appendix E <br /> 7 <br />