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Section 4 <br /> FIELD WORK <br /> BOREHOLE ADVANCEMENT AND SOIL SAMPLING <br /> Between December 2 and 10, 1992, fifteen exploratory soil borings (B-1 through B-15) were advanced and <br /> sampled at the locations shown on Figure 3. Borings B-1 through B-6 were located in the immediate <br /> vicinity of the two above-ground production fluids tanks. Borings B-7 through B-10 were located in the <br /> drainage ditch adjacent to the west side of the dehydrator station. Borings B-1 1, B-12 and B-15 were <br /> located near the reboiler unit, and borings B-13 and B-14 were located near the sumps. The boreholes were <br /> drilled and sampled to depths ranging from 4 to 10 ft. <br /> Each of the borings were performed using a manually operated sampling device(Environmental Subsoil <br /> Probe) which collects a continuous 1-inch diameter core of the subsurface soils in 3-ft intervals. The soil <br /> cores were retained in plastic liners and a portion of each core was capped, labeled with the borehole <br /> identification information,the date of sample collection, and the initials of the sampling personnel. The <br /> samples were stored in an ice chest which was maintained at approximately 4°C from the time of collection <br /> until delivery to the analytical laboratory. <br /> Soil from each sampling interval was screened with a photoionization detector for organic vapors. The soil <br /> was placed in a zip-lock plastic bag and warmed until moisture droplets formed inside the bag. The vapors <br /> from the bag were measured using a calibrated Photovac Microtip MP-1000 and recorded on the boring log <br /> form. <br /> Materials encountered during borehole advancement were described on a boring log by a PG&E geologist. <br /> This description included soil classification (Unified Soil Classification System, ASTM-2487-83), color, <br /> moisture content and consistency(in relative terms), and estimated degree of hydrocarbon content (PID <br /> measurements). Logs of the borings are presented in Appendix A. <br /> Selected soil samples from each borehole were submitted to a State of California-certified analytical <br /> laboratory(Chromalab, San Ramon) for chemical analyses. The soil samples were analyzed for total <br /> petroleum hydrocarbons as gasoline(TPH-G) by EPA Method 5030/8015, total petroleum hydrocarbons as <br /> diesel, kerosene, and motor oil (TPH-D, TPH-K and TPH-M0, respectively) by EPA Method 3550/8015; <br /> total oil and grease by Standard Method 5520 E&F, and benzene,toluene, ethylbenzene and xylenes <br /> (BTEX) by EPA Method 8020. <br /> cca09/17/93(9784a.doc)cp45) 4-1 <br />