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Mr. Bob Fratto a July 27, 1993 ; 1 Page 2 i. j1 Five boreholes were drilled to depths ranging from 71.5 to 85 feet. Four borings (TW1-TW4) were drilled 5 to 10 feet into groundwater. Boring SB 10 was drilled to a few feet from groundwater. Four of the borings (TVLW1-TW4) were continuously cored for lithologic identification and visual inspection of hydrocarbons. Four borings (TW4 excluded) were sampled every 5 feet using a California modified split spoon sampler, for possible laboratory submittal and lithologic samples. Four samples each from borings TW 1, TW2, TW3, and SB10 and one sample from TW4 were submitted to WEST Laboratory in Davis for analysis. Soil samples were analyzed for benzene, toluene, ethylbenzene, and total xylenes (BTEX) using Environmental Protection Agency (EPA) Method 8020/Purge-and-Trap, total petroleum 1 hydrocarbon (TPH) as gasoline using EPA Method 8015/Purge-and-Trap, and TPH as diesel and motor oil using EPA Method Modified 8015/Extraction. Laboratory results are discussed i in the Analytical Results section. Visual observations showed hydrocarbon-affected soil in borings TW2 and TW4. Colors that may be indicative of hydrocarbon-affected soil range from black to grayish green to green. Discoloration extended approximately 2 feet below the surface in TW2. Visual inspection of. the core from TW4 showed soil discoloration to approximately 44 feet and free oil to a depth of approximately 33 feet. The deepest recorded discoloration occurred in a sand at 44 vertical feet. A grab sample of the discolored sand was collected at 44.5 to 45.0 feet for laboratory y analysis. Soil samples were not collected within the free oil zones. F l F Boreholes were placed at a safe distance (at least 10 feet away) on each side of the open excavation, as shown on Figure 1. Boring SB 10 was placed in the area of a former steam plant approximately 25 feet west of TW1. Borehole TW4 was placed west of the open excavation to accommodate an angle boring that would horizontally and vertically extend i below the approximate center of the excavation. The boring was drilled 30 degrees from f j vertical. It was calculated that the boring extended approximately 47 horizontal feet and 81 vertical feet below the ground surface. The bottom of the borehole was calculated to reach the approximate center of the excavation and approximately 40 feet below the bottom of the deepest part of the excavation. Soil sampling using a California modified split spoon sampler k is not feasible during angle borings due to the mechanics necessary to drive the sampler. E Therefore, one grab soil sample for analytical purposes was collected directly from the core barrel. Temporary Well Installation and Water Level Measurements Four boreholes (TWl - TW4) were drilled approximately 6 to 10 feet into groundwater. Prior to drilling, groundwater was estimated to occur at 60 feet below ground surface but was encountered between 75 and 78 feet. A temporary well was installed in borings TW 1 - TW4 to measure groundwater levels and collect groundwater samples. Each temporary well } consisted of 2-inch Schedule 40 polyvinyl chloride (PVC) blank casing with 15 feet of slotted ; screen at the bottom. The wells remained in place until the casings were surveyed for relative elevations and groundwater samples were collected. Brawn and Caldwell 7603CORREM7603-OLL-1 Consultants