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Project No 58080-06-02 January 5, 1995 Page 4 j Groundwater samples were tested for TPHg/TPHd, BTEX/ MTBE and halogenated volatile , organics (VOC's) following EPA Test Methods 8015, 8020 and 601 respectively • A vapor extraction test was performed by extracting soil gas from vapor extraction wells VW-5 and VW-6 while measuring process flowrate, vacuum and temperature and monitoring vacuum response in other onsite and offsite groundwater monitoring and vapor extraction wells 1 FINDINGS ' Site Geology Fill soils were encountered to depths of between 4 and 10 5 feet bgs in borings GB-6, GB-7, GB8, ' GB-9 and GB-10 The fill soils are generally comprised of silty, fine to coarse grained sand and are similar in nature to the near surface alluvial deposits encountered in previous borings drilled at the site The alluvial deposits encountered underlying the fill soils generally consist of interbedded sand, silt and clay More specifically, an orangish brown silty fine- to medium-grained sand was encountered underlying the fill soils to depths on the order of 15 to 17 feet bgs Interbedded olive brown to greenish gray clayey sands and sandy clay, clay and silt was encountered underlying the orangish- brown silty sand layer These interbedded soil layers extend to depths on the order of 29 to 38 feet ' bgs A white to gray, fine- to medium-grained sand layer with low cohesion was encountered underlying the mterbedded clayey sands and sandy clay layers The sand is er was encountered in each of the borings and extends to a depth of approximately 4l feet_bgs Very stiff to hard olive to greenish gray, silty On andvery clavey sand was encountered beneath e sand layer, extending to depths on the order of 47 to 51 feet bgs Interbedded sand and clay strata, in thicknesses ranging rom to 3 feet, were encountered below the silty clay and clayey sand layer to 55 feet bgs Aquifer sediments were encountered at a depth of approximately 60 feet bgs and consist of dense or moderately dense fine to medium grained sand to the maximum boring ' depth of 71 5 feet bgs i Generalized north-south and east-west trending geological cross sections are presented as Figures 3 and 4, respectively Copies of boring logs and well completion diagrams are included in ' Appendix A ti 1 Site Hydrology Thee oundwater across the site measured on November 30, 1994 ranged from -9 81 to - 9 47 feet below Mean Sea Level (MSL), or approximately5 fee The direction of groundwater flow is generally to the south-soutlAcaLwith a gradient ranging from approximately 0 002 to 0 005 feet/foot A summary of the groundwater elevation measurements are presented on