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C 1 detected in either sample with the exception of benzene, which was detected at a concentration of 2.4 mg/kg from the sample collected at the south end of the former tank. g g P 3.0 SUMMARY OF ACTIVITIES DriIling and sampling services were performed by Fisch Environmental Exploration Services (Fisch) of Valley Springs California, a C-57 licensed drilling contractor. Borings were advanced using a Geoprobe®Model 5400 equipped with a GH-40 Soil Probing Hammer. Prior to drilling operations, Fisch obtained an "Application for Well/Pump Permit" from PHS/EHD to install the soil borings (Appendix A). DriIling and sampling activities were conducted on August 4, in general accordance with procedures described in the Work Plan. The initial boring (B4-1) was drilled to a total depth of 20 feet below ground surface (bgs) and was located approximately 10 feet away from the northeastern edge of the former tank (Figure 2). Per the Work Plan, continuous-core samples were collected from the initial boring using a 4-foot long, 2-inch diameter, Macro-Core Open Tube Sampler equipped with a clear, polyvinyl chloride (PVC) plastic liner. Following extraction from the Macro-Core Sampler, core tubes were typically cut in half, capped, labeled and temporarily stored=in an ice-cooled chest. A lithologic log was prepared during drilling based on examination of the soil cores and utilizing the Unified Soil Classification System and generally accepted geologic interpretive descriptions (Appendix A). Soil cores were examined for the presence of staining, discoloration, or odors indicative of .petroleum hydrocarbon contamination. In addition, a photoionization' detector (PID) was used to check for the presence of ionizable petroleum hydrocarbon vapors in the open borehole. No indications of petroleum hydrocarbons were noted during drilling of either of the two borings drilled at the site. Based on the lack of field evidence of PHC impacted soils, and in consultation with Margaret Lagorio and Carol Oz of PHS/EHD, who were on site during the drilling of the initial boring, two soil samples at 12 and 17 feet bgs were prepared from the soil cores for submittal to the laboratory for PHC analysis. Groundwater was noted to be flowing into the open borehole after the boring was advanced beyond about 17 feet bgs. A groundwater sample was collected after the boring was advanced to the total depth of 20 feet bgs. The groundwater sample was collected by inserting 1-inch diameter PVC tubing, machine slotted with 0.001-inch diameter openings, from the bottom of the boring to the surface. Prior to collecting the groundwater sample; the depth-to-water was measured using an electric water-level sounder inserted into the PVC tubing. One quarter-inch diameter Teflon tubing, equipped with a check valve at the submerged end, was then inserted 3 981I7ffVRJ' W4USTJNV.xrr L� IE;t BOYAJIAN .& ROSS, INC. Environmental Scientists & Engineers