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r constructed in these borings. This drilling was directed by ASE associate geologist Ian Reed. Undisturbed soil samples were collected at least every 5-feet as drilling progressed for lithologic and hydrogeologic description and for possible analysis. The samples .were collected by driving a split-barrel sampler lined with brass tubes using hydraulic direct push methods. Selective soil samples were immediately trimmed, sealed with Teflon tape, plastic end caps and tape, labeled, sealed in plastic bags and stored on ice f o r transport to Kiff Analytical, LLC of Davis, California under chain o f custody. Soil from the remaining tubes was described by the site geologist using the Unified Soil Classification System and was screened for volatile compounds using an Organic Vapor Meter (OVM). The soil was screened by emptying soil from one of the sample tubes into a plastic bag. The bag was then sealed and placed in the sun for approximately 10 minutes. After the volatile compounds were allowed to volatilize, the OVM measured the vapor in the bag through a small hole punched in the bag. OVM readings are used as a screening tool only, since the procedures are not as rigorous as those used in the laboratory. OVM readings can be found on the boring logs located in Appendix E. 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 and drill cuttings were contained in sealed and labeled 55-gallon steel drums and left on-site for temporary storage. This water will be transported to an appropriate facility for recycling. 7 . 0 SUBSURFACE LITHOLOGY AND HYDROGEOLOGY Sediments encountered during drilling generally consisted of silty clay and clayey silt from beneath the asphalt or grass surface to the total depth explored of 20-feet bgs. In soil borings MW-1, MW-3, and MW-4 there was a silty sand or sand zone encountered between 14.5 and 16-feet bgs. Groundwater was encountered between 5.5 and 6-feet bgs. The boring logs and well construction details are included as Appendix E. Geological cross-sections showing the permeability of the lithology beneath the site are presented as Figures 4 and 5. The locations of transects used for the geological cross-sections are shown. on Figure 6. The cross-sections show a lower permeability unit to the northwest, which is the downgradient flow direction. This indicates that there may also be some groundwater flow to the west and northeast 574 West Grant Line Road Report — October 2000 -6-