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Section 5 FIELD WORK BOREHOLE ADVANCEMENT AND SOIL SAMPLING On November 24 and 30, 1992, nine exploratory soil borings (B-1 through B-9) were advanced and sampled at the locations shown on Figure 5. Borings B-1 and B-2 were located in the immediate vicinity of the former reboiler unit and sump. Borings B-3 and B-4 were located adjacent to the former underground piping that ran from the dehydrator tower to the reboiler unit before the site was reconstructed. Borings B-5 and B-6 were located near the former above -ground production fluids tank and borings B-7 through B-9 were located off-site to ascertain if elevated levels of petroleum hydrocarbons extend beyond the north and east property boundaries of the site. The boreholes were drilled to depths ranging from 6 to 18%: feet. Soil borings B-1 through B-8 were advanced and sampled by a PG&E drilling crew using a Mobile B-80 truck -mounted, hollow -stem auger drilling rig under the direction of a State of California Registered Geologist. Soil samples were collected from the borings at five foot intervals using a 2 -inch I.D. split spoon sampler equipped with three 6 -inch brass liners. The split spoon sampler was driven ahead of the lead auger into the undisturbed soils using a 140 Ib. hammer with a 30 -inch drop. Generally, the lower or middle brass liner at each sampling interval was saved for possible chemical analyses. All sampling equipment was thoroughly cleaned before each use with a trisodium phosphate solution and potable water lofii.Y:a Soil from each sampling interval was screened for organic vapors using a photoionization detector. The soil was placed in a zip -lock plastic bag and warmed until moisture droplets formed inside the bag. The vapors from the bag were measured using a calibrated Photovac Microtip MP -1000 and recorded on the boring log form. The soil samples retained in the brass liners were covered at both ends with Teflon sheets and fitted with plastic end caps. All samples were labeled with the borehole identification information, the requested chemical analyses, date of sample collection, and the initials of the sampling personnel. The samples were stored in an ice chest which was maintained at approximately 4°C from the time of collection until delivery to a State of California -certified analytical laboratory (Chromalab, San Ramon). Boring B-9 was performed using a manually -operated sampling device (Environmental Subsoil Probe) which collects a continuous 1 -inch diameter core of the subsurface soils. The soil cores were retained in plastic liners and a portion of each core was capped, labeled and stored in an ice chest for submittal to a State of California -certified analytical laboratory (Chromalab, San Ramon). cca08/19/93(9660a.doc/cp43) 5-1