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TABLE 3 <br /> RELATIVE GROUNDWATER ELEVATIONS* <br /> October 7, 1993 <br /> ' Relative Depth to Groundwater Relative Groundwater <br /> Well No. Casing Elevation Elevation <br /> MW-1 98.16 60.47 37.69 <br /> MW-3 97.32 ---- ---- <br /> MW-4 98.30 60.75 37.55 <br /> ' MW-5 96.78 59.54 37.24 <br /> MW-6 97.60 59.81 37.79 <br /> MW-7 98.11 60.57 37.54 <br /> MW-8 97.94 60.27 37.67 <br /> ' Measurements ui teet <br /> ' 2.7.1 Drilling and Sampling <br /> In order to access the contaminated soil directly beneath the former tank, well RW-1 was <br /> drilled at a 15° angle (from vertical) from a surface location behind the building (Figure 3). <br /> The well was drilled to a total depth of 50 feet (true vertical depth of 48.2 feet) using a <br /> truck-mounted 10-inch hollow-stem auger rig. <br /> ' Discrete soil samples were collected at five-foot intervals using - <br /> smg a 1401b hammer to advance <br /> a split-spoon sampler loaded with three 2 by 6-inch brass sleeves. The number of blows <br /> required to advance the sampler 18 inches was recorded on the boring log (Appendix A). <br /> To avoid cross contamination, the sampling equipment was washed in a tri-sodium <br /> phosphate (TSP) solution and rinsed twice with water prior to each sampling run. <br /> ' After removal from the sampler, the he sample in the bottom tube was covered with aluminum <br /> sheets, capped, sealed with tape, and stored on ice pending transportation to Alpha <br />' Analytical Laboratories in Ukiah, California. Soil in the middle tube was extruded into a <br /> plastic bag and screened for volatile organic compounds using a photo-ionization detector <br />' (PID: Thermo Environmental 580A, 10.0 eV, calibrated to isobutylene). The reading was <br /> recorded on the boring log, and the soil was described in accordance with the Unified Soil <br /> Classification System (Appendix A). <br /> Geoingial Audit Servira,Inc, <br /> AAA PAM-29.9411.47 8 <br /> 1 <br />