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/f A S S 0 C I A T E S I N C <br /> encountered. When the sampler was advanced, O-ring seals and an expendable drive point <br /> provided a watertight system to ensure sample integrity. <br /> When the tool was advanced to the desired depth, extension rods were sent downhole to brace <br /> the bottom of the sample screen as the tool casing was retracted. When the casing was retracted, <br /> fJ. <br /> approximately 41-inches of screen with slot sizes of 0.004 inches was exposed. Teflon tubing <br /> with a check valve attached to one end was inserted down the casing until it was immersed in <br /> i_ groundwater. Water was then pumped through the tubing and to the ground surface by <br /> oscillating the tubing up and down. Groundwater samples were placed on ice and delivered under <br /> chain-of-custody documentation to State-certified Argon Laboratories Inc. for chemical analysis. <br /> Following soil and groundwater sample collection, the borings were backfilled with neat cement <br /> grout to the ground surface. <br /> 2.4 Soil and Groundwater Sample Analysis <br /> Five selected soil samples and all five groundwater samples were analyzed by Argon for TPHd by <br /> EPA Method 8015M. The analytical results for soil samples are summarized in Table 1 and the <br /> analytical results for groundwater samples are summarized in Table 3. Laboratory data sheets and <br /> chain-of-custody documentation are included in Appendix B. <br /> 3.4 SUBSURFACE CONDITIONS <br /> Fr <br /> Soils encountered beneath the site consist primarily of clay, to a depth of approximately 20 feet <br /> below grade. From approximately 20 to 26 feet bgs, soil consisted of silty sand. <br /> >' Groundwater beneath the site was encountered at depths ranging from 20 to 25 feet bgs. Based <br /> on historical groundwater monitoring data collected at the site, groundwater flows to the north. <br /> 4.0 RESULTS (' +,.I m o') <br /> r.. <br /> 4.1 Petroleum Hydrocarbons in Soil <br /> Results of laboratory analyses performed on selected soil samples indicate that TPHd was present <br /> only in the samples collected from boring SB 17. Field observations indicated that the samples <br /> exhibited background concentrations of organic vapors except from the 15 foot sample of SB 17. <br /> Soil sample SB17-15' contained TPHd at a concentration of 61 ppm. All the remaining soil <br /> '- samples were nondetect. Analytical results of soil samples are summarized in Table 1. <br /> w:162574162574.021reportslsup_sub_inv.doc 5 <br /> L� <br />