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ATTACHMENT C <br /> PILOT TEST WORK PLAN <br /> Objective <br /> This pilot test has been designed to document the positive affect of spray aeration on <br /> chloroform-affected groundwater discharged to the City of Tracy's infiltration basin (Basin) <br /> and record the concentration of chloroform in water re-infiltrating the subsurface. In addition, <br /> field data collected during the pilot test will help characterize the nature and extent of the <br /> hydraulic control created by extracting groundwater from a single well and discharging the <br /> effluent to the adjacent Basin. <br /> Concept <br /> Groundwater will be extracted from existing recovery well RW-1 located immediately north <br /> of the Basin (Figure 1). Effluent will be returned for infiltration back to the shallow water- <br /> bearing unit by pumping it through a spray head set up at the east end of the Basin (Figure 2). <br /> A schematic diagram of the extraction system is attached (Figure 3). Treatment of the <br /> extracted groundwater is expected to occur through volatilization of chloroform as the water <br /> droplets fall to the foot of the Basin. <br /> Recirculation of the treated water is expected to enhance remediation of subsurface materials <br /> by washing chloroform from the unsaturated zone into shallow groundwater, where it will be <br /> transported to the extraction wells and removed. The groundwater mounding immediately <br /> beneath the Basin is expected to be controlled, hydraulically, by the extraction well. Lateral <br /> movement of groundwater is not expected beyond the capture zone created by extraction well <br /> RW-1. <br /> Pilot Test <br /> The pilot test is expected to occur over four to five days. The first three days will include test <br /> preparation activities. The pilot test will be completed on the fourth, or possibly fifth, day. <br /> Set-up. The pump in well RW-1 will be tested to see if it is still operable. <br /> Approximately 200 gallons of water will be pumped from the well into a portable above- <br /> ground storage tank. If the pump is found to be inoperable, it will be replaced prior to test <br /> initiation. A small, portable, gas-powered generator will be used as the on-site power supply <br /> throughout the preparation and testing periods. Prior to testing the pump, water levels in all <br /> site-related monitoring wells will be recorded. If accessible, static water levels will also be <br /> recorded in the two extraction wells. <br /> 05/07/98\c:Ua\2092\2092-14\Rspnsl2.doc\(pw) Page I <br />