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' GeoHydrologic Consultants, Inc <br /> The groundwater extraction wells will consist of the pump wells that were tested (EW-5D <br />' and EW-5S) and four other wells (TB-7, TB-10, MW-2, and MW-4) containing elevated <br /> levels of dissolved gasoline constituents (Figures 5A, 5B, and 5C) The pumps placed in <br /> TB-10, MW-2, and MW-4 will need to be 1 5-inch diameter pumps capable of producing <br />' between 0 25 to 2 25-gallons per minute and should be set at depths of approximately <br /> five feet from the bottom of each respective well The pumps placed in EW-5D, EW-5S, <br /> and TB-7 will need to be 2 0-inch diameter pumps capable of producing between 0 25 to <br /> 2 25-gallons per minute and should be also be set at depths of approximately five feet <br /> from the bottom of each respective well It is estimated that approximately 285 feet of <br /> trenching will be required in order to bury the secondary containment line at an estimate <br />' cost of approximately $30,000 to $40,000 including saw cutting, removal, trenching, <br /> installation of the two-inch diameter secondary containment piping, installation of liquid <br /> discharge and air supply hoses, pressure testing of lines, backfill and compaction, <br /> resurfacing, and removal of construction debris <br /> These pumps will be operated between approximately 0 25 to 2 25-gallons per minute <br />' depending on the yield of each well Groundwater will be discharged back to the <br /> treatment compound from each well with %-inch flexible discharge line The discharge <br /> lines will be placed inside individual two-inch diameter PVC conduits leading back to the <br />' treatment compound (Figure 10) A flow meter totalizer will be installed between the last <br /> carbon vessel and the discharge point The combined system flow rate is estimated to be <br /> between five and ten gpm <br /> 9.1 Closure Sampling <br />' Quarterly groundwater monitoring and vapor influent sampling will be used to establish <br /> the quality of groundwater beneath the Site over time and to monitor the effectiveness of <br /> long-term vapor/groundwater extraction and treatment remediation activities Once <br /> tasymptotic vapor concentrations are reached and maintained, and reasonable groundwater <br /> goals are reached, the long-term remedial activities will cease and the vapor wells will be <br /> tested for rebound If no significant rebound is observed, soil confirmation sampling will <br />' be performed <br />' 9.2 Conclusions <br /> Soil and groundwater beneath the Site has been impacted with petroleum hydrocarbon <br />' constituents (TPHg, BTEX, and MTBE) The soil and groundwater plumes beneath the <br /> Site can be effectively remediated by using long-term vapor/groundwater extraction and <br /> treatment with a fixed permanent oxidation system Pilot tests have already been <br />' performed which demonstrated the effectiveness of this technology at the Site at reducing <br /> the relatively moderate concentrations and mass that are present in the subsurface, the <br /> results which have been incorporated in to the remedial design included in this Remedial <br />' Action Plan Vapor extraction is currently being performed effectively at the Site <br /> Removal of source material through long term vapor/groundwater extraction and <br /> treatment should eliminate any continued contribution to groundwater contamination thus <br />' TOC 171 Pilot Study Page 26 <br />