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5 August 1992 (GeoAudit CV 30-34E3-1.47) Page 2 of 6 i1 MONITORING WELL INSTALLATION AND SAMPLING � Two additional monitoring wells were installed on 22 and 23 June x 1992 (Figure 2) . MW-4 was installed approximately 50 feet northeast of MW-1. MW-5 was installed immediately adjacent to MW-2 . I The borings were advanced to a h using a truck ;. mounted 8-inch hollow-stem auger rig. The "r -2 drill rig and two man crew were supplied by West Hazmat Drilling Corporation. t Discrete soil samples were collected ahead of the drill bit using a split-tube sampler loaded with three pre-cleaned 2. 5 by 6 inch brass tubes. The samples were obtained at five foot intervals. To avoid cross contamination, the sampling equipment was washed in a tri-sodium phosphate (TSP) 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 stored on ice pending transmission to a state certified laboratory N - (Alpha Analytical Laboratories in Ukiah) . Selected samples were analyzed for TPH as gasoline, BTE&X and total lead. Soil from the second brass tube was extruued and screened for the presence of organic vapors using a photo-ionization detector (PID: Thermo Environmental 580A, 10. 0 eV, calibrated to isobutylene) . The ;. soil was then describers in accordance with the Unified Soil Classification System (see Boring Logs) . The borings were completed as groundwater monitoring wells by the installation of 0. 020 screen PVC liner. MW-4 was screened from 49 to 74 feet. Bentonite pellets were used from 47 to 49 feet and the ' well was backfilled to the surface with Portland Cement. MW-5 was m screened from 50 to 75 feet. Bentonite pellets were used from 48 to 50 feet and the well was backfilled to the surface with Portland I, Cement. All five on-site wells were surveyed on 30 June 1992 and water levels were measured. Water samples were collected from the new wells (MW-4 and MW-5) , but neither MW-1 nor MW-3 could be sampled due to low water levels (although the depth to water could be measured in MW-1) . A PVC bailer. as used to surge and purge the . —+i.., ...... ..trt✓a..xJ3LibM14Gi� ! .y�uP�yciv�^aa W& Wuni Wele et:A1uVCl1 Liulu eaQh well prior to sample collection. Water temperature, pH and conductivity were measured at one gallon intervals using a Hydac water analyzer (Table 3) . The purged water was stored in a 55- gallon drum on site. Awl .