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i i Since borings MW-11 through MW-12 were drilled near previous CPT borings for the installation of groundwater monitoring wells, and since the sandy sediments present beneath the site presented the possibility of heaving (flowing) sands during drilling, the bottom of the auger was iplugged with a wooden block and no soil sampling was conducted in these borings In these borings, the drilling was halted at the desired depth o f the bottom of the well to be constructed, and the wooden plug at the bottom of the augers was knocked out with a 140-1b hammer dropped through the augers prior to the construction of the monitoring wells i Drilling equipment was steam-cleaned prior to use, and sampling equipment was washed with a TSP solution between sampling intervals to prevent cross-contamination Rinsate was contained on-site in sealed and ilabeled 55-gallon steel drums Drill cuttings were contained in steel bins and were transported to Forward Landfill for disposal i 5 . 0 SUBSURFACE LITHOLOGY AND HYDROGEOLOGY Sediments encountered during drilling generally consisted of sand of relatively high permeability from beneath the asphalt/concrete surface to approximately 18-feet bgs, followed by low permeability clayey and silty isediments from approximately 18-feet bgs to approximately 37-feet bgs Below 37-feet bgs lies sediments with high permeability until a depth of at r least 50-feet bgs is reached Below 50-feet bgs, the sediment layers 1 become discontinuous with high, medium and low permeability layers at various depths in different portions of the site until a depth of 120-feet bgs in reached where a relatively continuous layer of low permeability sediments is encountered At a depth of 130-feet bgs, a relatively continuous layer of high permeability sand is encountered Two geologic icross-sections have been prepared for this site The location of the geologic cross-sections is shown on Figure 4, and the geologic cross- sections are presented as Figures 5 and 6 Groundwater was encountered between 11 and 12-feet bgs The boring logs and well construction details are included as Appendix C 6 . 0 ANALYTICAL RESULTS FOR SOIL i The soil samples collected from 11 5-feet bgs (the capillary zone) in borings P-1, P-2, P-3, P-4, MW-13 and MW-14 were submitted to Kiff Analytical of Davis, California (ELAP 2236) for analyses The soil samples i Franks One Stop Report — May 2000 -8-