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l Section 5 FIELD WORK PROCEDURES BOREHOLE ADVANCEMENT AND SOIL SAMPLING On November 23 and 24, 1992, nine exploratory soil borings (B-1 through B-9) were advanced and sampled at the locations shown on Figure 4. Borings B-1 and B-3 through B-6 were located in the immediate vicinity of the former reboiler unit and borings B-2, B-7, B-8 and B-9 were located near the east, south,west and northwest boundaries of the site, respectively(B-2 was drilled off site). The purpose of borings B-1 and B-3 through B-6 were to assist in defining the lateral and vertical extent of the potentially impacted soils. Borings B-2, B-7, B-8 and B-9 were drilled to ascertain if elevated levels of petroleum hydrocarbons extend beyond the property boundaries of the site. The boreholes were drilled to depths ranging from 13'/�to 20 feet. Soil borings 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 lb. 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 a potable water rinse. 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). Materials encountered during the drilling were described on a boring log by a PG&E geologist. This description included soil classification (Unified Soil Classification System, ASTM D-2487-83), color, cca/08/18/93/9449arpt.doc/mkn4 5-1