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til exhaust hose to measure the concentration of hydrocarbon vapors being withdrawn In the boring through the former dispenser island, three readings were made 11 feet, 12 5 feet, and 14 feet A sample was also collected at 12 5 feet in a tedlar bag and was transported to Sequoia Analytical for laboratory analysis The laboratory report is included in Appendix A ' i 3.2 Results I Significant soil vapors were detected only in the probe through the dispenser island PID concentrations of 360 ppm, 660 ppm and 970 ppm were measured at 11, 12 5, and 14 feet, respectively Concentrations of 15 ppm and 5 ppm were detected briefly in the two probes to the north and northeast of the dispenser island (Figure 3) The laboratory reported concentrations of 450 ppmv TPH-g, 2 5 ppmv toluene, 17 ppmv ethylbenzene, and 60 ppmv xylene The concentration of benzene was below the detection limit of 0 016 ppmv 4.0 SOIL BORINGS 4.1 Procedures Soil borings were drilled with a standard Mobil Drill B-61 auger rig Three borings were planned, including one monitoring well, but only two were drilled, neither of which was completed as a monitoring well, for reasons that are explained below Figure 2 shows the location of the new borings The first boring, HP-4, was drilled to a total depth of 75 feet on March 23 Samples were collected continuously from 5 feet to 40 feet and described in detail on the boring log in order to provide a highly accurate profile of the subsurface soil types through the contaminated zone Samples were collected at 5-foot intervals from 40 to 75 feet Selected samples were screened with the PID and preserved for laboratory analysis The boring log is included in Appendix B Saturated soil conditions were encountered at a depth of 39 feet, and a hydropunch sampler was used to collect a groundwater sample dust below this depth The sampler filled rapidly and three 40-m1 vials and a 1-liter bottle were collected for laboratory analysis Drilling then continued to the 75-foot depth, at which point a Simulprobe sampler was used to collect discrete soil and water samples at this depth, as required by PHS/EHD The boring was then backfilled with cement grout from total depth to the surface, using a tremmie pipe A total of 15 soil samples and two water samples were sent to various laboratories for analytical tests The results are discussed in section 4 2 and the laboratory reports and chain of custody forms are included in Appendix C The work plan called for leaving the augers in the hole overnight and analyzing the Simulprobe water sample on 24-hour turnaround in order to determine whether the water at that depth is contaminated PHS/EHD had requested that the well be completed as a dual-zone well if contaminated groundwater was detected at 75 feet However, we decided to analyze the sample on 48-hour turnaround and return to the site later in the week to drill the monitoring well 5