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i <br />Groundwater samples collected from wells MWl and MW2 and soil boring SBS had non- <br />detectable TPHg, BTEX, and MTBE. Hydropunch groundwater samples collected from soil <br />borings SB6 through SB8 contained TPHg concentrations ''ranging from 400 to 5,500 parts per <br />billion (ppb) and benzene concentrations ranging from 2.4t to 120 ppb. Figure 3 shows TPHg <br />concentrations in groundwater. Groundwater analytical ''esults are summarized in Table 2. <br />Appendix E contains laboratory reports and chain of custody documentation for soil and <br />groundwater samples. <br />�.: 3.2.3 Biophysical Laboratory Results <br />A number of physical, chemical and biological tests were!irun on soil samples to provide data <br />on leaching potential, adsorption potential and biodegradation potential. <br />LBiodegradation Potential <br />Biological amenability tests were run on two soil samples from boring SB -8, from an elastic silt <br />at a depth of 25.5 feet (S-SB8-25.5) and a second elastic . silt at a depth of 36 feet (S-SB8-36). <br />These samples were selected for biological testing because'boring SB8 is located in the area of <br />formerl identified soil impact and in the <br />Y p heart of the groundwater plume. Analyses consisted <br />Cof aerobic and. anaerobic plate counts (bacteria) and PKN. <br />The results of the physical and chemical/biological parameters are presented in the laboratory <br />analysis reports included in Appendix E. The levels of phosphorus and potassium nutrients are <br />sufficient to support bacterial degradation of gasoline hydrocarbons. Nitrate was detected at a <br />relatively low level. However, bacterial counts were in the 108 range, well above the 106 colony <br />r forming units typically encountered in an active colony of hydrocarbon degrading bacteria. The <br />conclusion drawn from these results is that a suitable substrate exists for biodegradation of the <br />hydrocarbons identified at the site and that degradation is indeed occurring. The relatively high <br />r <br />soil pH (8.4-8.9) may also be indicative of biological activity, as we normally see a relative <br />increase in alkalinity with intrinsic bioremediation. <br />groundzeVanuio\closure 7 <br />