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October 25, 1993 3A Soil Borings and Sal Sampling Methodology Three borings were drilled and two wells were installed on September 27, 1993 The borings were drilled using a Mobile B-61 drilling ng equipped with 8-in diameter, continuous- flight, hollow-stem augers and operated by Woodward Drilling of Rio Vista, California, a licensed well duller The auger-flights were steam-cleaned prior to use in each boring to nunimize the possibility of downhole or cross-bonng contamination The drilling was observed by our field geologist and the soil units encountered in the borings were logged as the borings were dulled Soil boring logs are presented in Appendix A One soil boring was drilled at an angle of 300 to vertical and extended to a vertical depth of 33 5 ft The borings dniled for C constructing wells extended to depths of 50 ft During g samples drilling, soil les were collected atapproximate 5-ft intervals using a p California-modified, split-spoon sampler equipped with clean brass sleeves Samples were collected by advancing the boring to a point immediately above the sampling depth, then driving , the sampler into the native soil through the hollow center of the auger The sampler was driven 18 in with a standard 140-1b hammer dropped 30 in' The number of blows required to drive the sampler each successive 6-in interval was counted and recorded to give an indication of soil consistency ` ` - Drill cuttings were left at the site with the stockpiled soil from the excavation of the - - ..waste_oil___ tank pit pending the results of analyses Disposal of the soil remains the responsibility of the client RFA can arrange to mitigate soil contamination or to-have the soil-removed to an appropriate d si so al-facility wtti�the-authorization of-the client The lower sleeve of each soil sample was sealed with aluidminum foil,-plastic end caps,— - and duct tape These sample sleeves were labeled and placed in iced storage for transport to our office and then to the analytical laboratory Soil samples were selected for chemical analyses from each boring based on readings obtained from a photoionizing organic vapor meter (OVM) and proximity to the groundwater surface OVM readings were obtained by placing a portion of the contents of the middle sample sleeve into a sealable plastic bag and (� disaggregating the sample core After a period of two to three minutes, the intake probe of the OVM was inserted into the bag The maximum reading obtained for each sample was recorded, these values are shown on the boring logs Samples were described using the Unified Soil Classification System and descriptions of the materials encountered are presented in the Logs of Borings (Appendix A) Chain of Custody Records were initiated by the field geologist and ROGER -4- FMTT ASSOCIATES