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sufficiently below the bottom elevation of the former tank, soil samples for PHC analysis will ' <br /> be obtained from the cores at 5-foot intervals starting at 2 feet below the bottom elevation of <br /> the former tank and ending 2 feet above the water table In addition, a groundwater sample <br /> will be collected from the first transmissive zone below the water table ' <br /> If the water table is sufficiently below the bottom elevation of the former tanks, a boring will <br /> be advanced approximately between the two former tanks near the south end of the excavation ' <br /> (the south end had the higher PHC concentrations beneath both tanks). Soil samples will be <br /> collected at 5-foot intervals starting at 2 feet below the bottom elevation of the tank and ending ' <br /> 2 feet above the water table At a minimum, the two lowermost soil samples will be analyzed <br /> for PHCs. A third boring (133-3, Figure 3) will be advanced outside the tank excavation limits <br /> Soil and groundwater samples for PHC analysis will be collected as for the initial boring <br /> If the water table is within 5 feet of the bottom elevation of the former tanks, no boring will <br /> be advanced within the former excavation Instead, two additional borings (B3-2 and 133-3, ' <br /> Figure 3) will be advanced In a radial pattern around the former excavation and within 10 feet <br /> of the former tanks Groundwater samples will be collected in these borings from the first ' <br /> transmissive zone below the water table Soil samples for PHC analysis will be collected as <br /> for the initial boring <br /> 3.1.2 Methodology <br /> The field investigation will be carried out in general accordance with Tn-Regional_Board Staff I <br /> Recommendations for Preliminary Investigation and Evaluation of Underground Storage Tanks <br /> (North--Coast-Regional=Water-Quality ControlY-Board,Wal,1990)--Soil-bonngs will-be <br /> advanced, sampled, and backfilled according to the procedures given in Appendix B, utilizing <br /> the Geoprobe direct-push method Soil samples will be collected for PHC analysis according <br /> to procedures given in Appendix C Groundwater samples will be collected for PHC analysis ' <br /> according to procedures given in Appendix D <br /> Collected soil samples will be field-screened using procedures presented in Appendix C Field ' <br /> screening procedures include examination of soil for lithologic character, odor, unusual <br /> staining, and detection of organic vapors (using a photolonization detector) After completion <br /> of soil sampling, the borehole will be backfilled using a sand-cement slurry containing five <br /> percent bentonite as described in Appendix B. <br /> Unused soil samples from the boring and nnsate from decontamination of probe equipment will ' <br /> be containenzed in U S Department of Transportation approved 55-gallon drums These <br /> drums will be properly sealed and labeled, and will be secured within a fenced area of the <br /> 6 991171,MUSrw wPN <br /> 1 <br />