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1 approximately 42 feet Subsequently,groundwater depth fell below 55 feet and all wells were dry. In order to continue the groundwater investigation, we recommended the installation of additional monitoring wells. Furthermore, we recommended the drilling of one or two soil bonngs within 10 to 15 feet of the extraction well to confirm the successful removal of contaminants from the soil This report describes the installation of these bonngs and groundwater investigation 3.0 PROCEDURES 3.1 Drilling and Sampling On June 13 and 14, 1994, four soil bonngs were dnlled at the site Borings MW-8 and MW- 9 were advanced to depths of 75 feet and completed as groundwater monitoring wells Borings CB-1 and CB-2 were advanced to a depth of 65 feet and backfilled in the entire depth with Portland cement Auger returns were placed on plastic sheeting and stored on- site The boring locations are depicted in Figure 2 The bonngs were drilled using a truck-mounted B-61 HDX drill ng The drill rig and two- man crew were supplied by V & W Drilling of Rao Vista, California 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) 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 To avoid cross- contamination, the sampling equipment was washed in an alconox solution and rinsed twice with water prior to each 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 Alpha Analytical Laboratories in Ukiah, California (AAL) 3.2 Logging Soil was extruded from the second brass tube and screened for the presence of organic vapors, using a PID, and the readings were recorded on the boring logs The soil was then described in accordance with the Unified Soil Classification System (see Bonng Logs, Appendix B) 3.3 Well Completion and Backfilling Borings MW-8 and MW-9 were completed as groundwater monitoring wells using 2-inch diameter PVC casing with 0.020 screen from 55 to 75 feet The filter pack (#3 Lonestar 0--kV-1 A-&$., 1 c C ()...en Salary QR!!9Vl 1 5