ARCHIVED REPORTS_XR0003686 - Laserfiche WebLink

Home Browse Search

S . 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 predominantly low permeability clayey and silty sediments from approximately 18-feet bgs t o approximately 35-feet bgs Below 35-feet bgs lies sediments with high permeability until a depth of at least 52-feet bgs is reached Below 52- feet bgs, the sediment layers become discontinuous with high, medium and low permeability layers at various depths in different portions of the site until a depth of 125-feet bgs in reached where a relatively continuous layer of high permeability sand is encountered The lithology of the new borings is relatively consistent with the lithology in borings previously drilled at the site In addition, the lithology described by the CPT is relatively consistent with geologist's logs Two geologic cross-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 5 and 13 5-feet bgs The boring logs and well construction details are included as Appendix D 6 . 0 ANALYTICAL RESULTS FOR SOIL iSoil samples collected from 11 5-feet bgs in borings MW-19, RW-1 and RW-3, and 110-feet bgs in boring MW-20 were submitted to Kiff Analytical of Davis, California (ELAP 2236) for analyses These depths represent the capillary zone in each boring All of the samples were analyzed for TPH-D by modified EPA Method 8015 and TPH-G, BTEX, HVOCs, oxygenates and alcohols by EPA Method 8260 The analytical results are tabulated in Table One A copy of the certified analytical reports and chain of custody forms are included in Appendix E The soil sample from 11 5-feet bgs in boring RW-1 contained 200 p p m TPH-G, 77 ppm TPH-D, 0 008 ppm benzene, 0 86 ppm toluene, 1 0 p p m ethyl benzene, 7 9 ppm total xylenes and 0 012 ppm MTBE The soil sample from 11 5-feet bgs in boring RW-3 contained 86 ppm TPH-G, 14 0 ppm TPH-D, 0 011 ppm toluene, 0 10 ppm ethyl benzene, 0 81 ppm total xylenes, and 0 0079 ppm MTBE Please note that although hydrocarbon concentrations were detected in the diesel range in both of these samples, the laboratory reported that the chromatogram patterns resembled that • of aged gasoline rather than diesel No hydrocarbons were detected in t h e Franks One Stop Report — November 2000 -11-