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March 17, 1999 <br /> Page 3 <br /> BTEX, and MtBE Additionally, the groundwater samples were <br /> analyzed for the oxygenates MtBE, Ethanol, Methanol, TBA, DIPE, <br /> ETBE, and TAME by EPA Method 8260 <br /> • Well Surveying. The wells were surveyed for location and elevation <br /> relative to mean sea level (MSL)by a California State-certified <br /> surveyor Surveyor's map and data are presented as Attachment C <br /> FINDINGS <br /> Subsurface Conditions <br /> Soils encountered during drilling (maximum explored depth of approximately 39 feet <br /> bgs) consisted of sandy silt, silty sand, and sand These conditions are consistent <br /> throughout the site A more complete descnption of the subsurface lithology is shown <br /> on the boring logs presented in Attachment A <br /> Groundwater was first encountered at approximately 11 to 14 feet bgs and stabilized at <br /> approximately 11 feet Groundwater elevation data for the October 8, 1998 sampling <br /> event indicate that the direction of groundwater flow beneath the site on that date was <br /> toward the north-northwest at an approximate gradient of 0 002 A groundwater <br /> contour map is presented as Figure 3 <br /> Soil Analytical Results <br /> Maximum TPH-g concentrations were detected in well MW-3 at 16 feet bgs at 6,800 <br /> ppm Benzene was detected in maximum concentrations in the sample collected from <br /> well MW-4 at 15 feet bgs at 14 ppm Maximum MtBE concentrations were detected <br /> well MW-2 at l l feet bgs at 7 2 ppm A soil sample collected from GP-1 at 39 feet bgs �[ , <br /> reported non-detect for TPH-g, benzene and MtBE All maximum concentrations were <br /> detected within the capillary fringe Soil analytical data are summarized below and are ,f <br /> presented in Table 1 and Figure 4 <br /> Physical parameter data is presented as Table 3 <br /> Groundwater Analytical Results <br /> Maximum TPH-g concentrations were detected in MW-1 at 29,000 parts per billion <br /> (ppb) This location was immediately downgradient and within approximately 12 feet <br /> of the former underground storage tanks Maximum benzene and MtBE concentrations <br /> were detected in MW-2 at 210 and 4,000 ppb respectively Groundwater analytical data <br /> are summarized below and are presented on Table 2 and Figure 5 <br />