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( Applied Geotechnology Inc. <br /> I " <br /> IAPPENDIX B <br /> Field Exploration and Sampling <br /> The following sections describe the field work performed for our <br /> environmental assessment of USG Interiors' facility at 1433 Tillie Lewis <br /> Drive, Stockton, California. <br /> Subsurface Exploration <br /> Subsurface soil and groundwater conditions were explored by drilling a <br /> total of four soil borings using a truck-mounted Mobile 3-57 drill rig <br /> equipped with a 4-inch inside diameter continuous flight hollow-stem auger. <br /> No water was added to the borings during drilling. <br /> All drilling equipment was thoroughly decontaminated prior to drilling the <br /> first boring, between subsequent borings, and after completing the final <br /> boring. Drilling equipment was decontaminated using a high-pressure steam <br /> cleaner. <br /> Soil and groundwater conditions were characterized and logged using the <br /> following methods: <br /> i. o Regularly examining the drill cuttings removed from the borehole. <br /> L <br /> o Observing the resistance to drilling, as indicated by the drilling <br /> (l rate, rig pressure applied, and overall rig behavior. <br /> t_ o Obtaining relatively undisturbed soil samples at regular <br /> intervals, as described below. <br /> Soil samples were collected at 2 1/2-foot intervals with a 2 inch inside <br /> diameter split barrel sampler with brass tube liners. All soil samples <br /> were visually examined in the field at the time of collection, and <br /> described in general accordance with the Unified Soil Classification <br /> System, ASTM Test Method P-2487-83. Based on visual, olfactory, and/or OVM <br /> evidence for contamination, soil samples were not selected for chemical <br /> analyses. <br /> Soil samples were checked while drilling PW-1 and PW-2 for organic vapors <br /> in a systematic manner. Disaggregated samples (approximately the same <br /> mount each time) were placed in a plastic resealable bag immediately after <br /> removal from the split barrel sampler and sealed. The soil was allowed to <br /> equilibrate in the air space (headspace) for approximately 5 minutes. The <br /> OVM-PID probe was then inserted through the bag into the headspace above <br /> the soil. No detections were found in any soil samples from PW-1 and PW-2, <br /> as a result no soil samples from PW-3 and PW-4 were tested. <br /> L_ <br /> I. <br />