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site The first boring (MW-5) was drilled using a truck-mounted B-61 HDX drill rig The drill rig and two-man crew were supplied by V & W Drilling of Rio Vista, California During well completion, the borehole "squeezed" at a depth of approximately 60 feet, and the well had to be abandoned On January 14, 1994, Turner Exploration of Rancho Cordova redrilled MW-5 and drilled borings B7 and B8 Monitoring well MW-6 was drilled on January 17, 1994 by Turner Exploration A truck-mounted BK-81 drill rig was used to install these borings During drilling, auger returns were monitored for the presence of organic vapors using a photo-ionization detector (PID Thermo Environmental 580A, 10 0 eV, calibrated to isobutylene) ' In three of the borings, soil samples were collected ahead of the drill bit using a split-tube sampler loaded with three pre-cleaned 2-inch by 6-inch brass sleeves The samples were collected at five-foot intervals, using a 140-pound hammer to advance the sampler 18 inches The number of blows required to advance the sampler in 6-inch increments was recorded on the boring logs A continuous core sampler was used to sample boring MW-6 from 20 feet to 75 feet Samples were collected in this interval by pressing a brass tube into the core sample at the desired sample depths To avoid cross-contamination, the sampling equipment was washed in a tri-sodium phosphate (TSP) solution and rinsed twice with water prior to Ieach sampling run For each sample, both ends of the lead tube were covered with aluminum sheets, capped and sealed with tape The samples were then stored on ice and transported under chain of custody to McCampbell Analytical Inc in Pacheco, California (MAI) 3.2 Logging The continuous core was described in detail on the boring log (Appendix A) The other ' borings were logged by extruding soil from the middle and upper bi ass-tubes Samples were then screened for the presence of organic vapors, using a PID, and the readings were recorded on the boring logs Due to background interference, high PID readings were recorded even where no hydrocarbon odors were present in the samples ' 3.3 Well Completion Barings MW-5 and MW-6 were completed as groundwater monitoring wells using 2-inch diameter PVC casing with 0 020 screen from 65 to 85 feet The filter pack (#3 Lonestar I sand) was installed from 85 feet to 63 feet in MW-5 and from 85 feet to approximately 59 feet in MW-6 Bentonite chips were used to make a 3-foot plug and the wells were grouted ' to the surface with Portland cement Borings B-7 and B-8 were grouted horn total depth to the surface with Portland cement Ge0I0yaA-&SeNKYa LAC Loci¢ford Sema QRA 94H645