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.. Y:yr 67. ri; <br /> 7� S <br /> F <br /> f <br /> - 0 Pacific Gas and Electric <br /> Pacific Telephone <br /> US Sprint <br /> Continental Cable, and <br /> California Water Service. <br /> None of these companies reported underground utility lines at the <br /> site. <br /> Soil borings were placed in the area of the former excavation in order <br /> to obtain a preliminary assessment of the horizontal and vertical <br /> extent of the contamination (Figure I-4)• Three borings (3, 6, and 9) <br /> were selected in areas of known contamination to determine the <br /> vertical extent of contamination. Seven other sampling locations <br /> were selected around the perimeter to provide a prelimii.,`�'Y <br /> assessment of the horizontal extent of contamination. <br /> Borings were drilled using a truck-mounted drilling rig equipped <br /> with continuous flight augers. All drilling and sampling equipment <br /> was steam cleaned prior to drilling each boring to prevent <br /> contamination between borings. Borings were logged in accordance <br /> with the Unified Soil Classification System (See Appendix B). The <br /> boring logs may bE found in Appendix C. <br /> Sampling commenced at the interface between the fill material and <br /> the native subsoil. Samples for laboratory analysis were taken with a <br /> California Modified Split-spoon sampler equipped with brass tubes. <br /> �- Some samples were taken without brass tubes for purposes of logging <br /> relatively undisturbed soils. The samples were observed for texture, <br /> moisture, and staining or odor. Samples were taken to characterize <br /> the level of contamination observed in the field. In addition,a bottom- <br /> � of-the-hole sample .was collected in every boring to verify any field <br /> observed absence or presence of contamination. <br /> After the last sample from each boring was collected and observed for <br /> signs of contamination, two to three samples were selected for <br /> analysis. Sample selection was based on odor and visual observation <br /> with the objective of defining the vertical extent of the contamination <br /> in each boring. A photoionization detector (PID) was also employed <br /> initially to help detect petroleum hydrocarbon vapors in the soil <br /> M_ samples. However, due to the lour volatility of the.contaminants, the <br /> PID tended to pull in more ambient air than volatilized contaminants <br /> which resulted petroleum <br /> ium odors r Therefore,e, theA even e use elof the PIDersonnelwas <br /> -. oted <br /> stroaig p <br /> discontinued after the third boring. <br /> 1-8 <br />