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3. 0 PROCEDURES 3.1 Drilling On August 16, 1993 , six soil borings were drilled at the site. Borings B1, B2 and B3 were advanced to depths of 35 feet. Boring B4 was advanced to a depth of 40 feet. Borings B5 and B6 were drilled at an angle of 300 towards the west and advanced to depths of 6 feet (approximately 5 vertical feet) . The location of the borings is shown on Figure 2 . The borings were advanced using a truck-mounted drilling rig equipped with 8-inch outside diameter hollow-stem augers. The — Mobile B-53 drill rig and crew were supplied by Turner Explorations, Inc. Auger returns were placed in 55-gallon DOT drums and stored on site. Each boring was backfilled using a concrete- bentonite slurry for the entire depth. 3.2 Soil Sampling Discrete soil samples were collected at 5-foot intervals ahead of the drill bit using a split-tube sampler loaded with three pre- cleaned 2 by 6-inch brass tubes. The sampler was driven into the soil with a 140-1b hammer, and the number of blows required to advance the sampler in 6-inch increments was recorded on the boring logs (Appendix B) . 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 :pealed with tape. The samples were then labeled, logged on a chain of custody and stored on ice pending transmission to McCampbell Analytical in Pacheco for analysis. 3.3 Logging Soil sample duplicates were described in accordance with the Unified Soil Classification System. The auger returns and soil sample duplicates were monitored for the presence of organic vapors using a photo-ionization detector (PID: Thermo Environmental 580A, 10. 0 eV, calibrated to isobutylene) . 3 .4 Laboratory Analysis - Ms. Diane Hinson of the PHS/EHD selected a total of 10 soil samples from borings #1 through #4 for analysis of total petroleum hydrocarbons (TPH as gasoline) and purgeable aromatics (BTE&X) in accordance with EPA methods 80215 modified and 8020, respectively. No samples from borings B5 and B6 were analyzed. 2