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Extracted Ground Water Treatment Objective <br /> Ground water extracted at dual phase extraction wells and plume margin <br /> wells will be routed to the Treatment System. There are three treatment <br /> mechanisms for ground water treatment prior to recharge. These are: <br /> • In Situ Stripping within the Extraction Tube Ground water <br /> extracted at dual phase extraction wells is subject to the stripping <br /> action within the extraction tube. <br /> • Treatment at the Multi-Stage Diffuser Ground water extracted at <br /> both plume margin ground water extraction wells and at dual <br /> phase extraction wells will be processed through a multi-stage air <br /> diffuser. The VOC-laden vapor effluent stream from the multi- <br /> stage air diffuser will be routed to the catalytic oxidizer. <br /> • Treatment by Carbon Adsorption Treated ground water effluent <br /> from the multi-stage air diffuser will be subject to a final polishing <br /> step by processing through two 1,800 lbs granular activated carbon <br /> vessels installed in-series. Following the carbon polishing step, <br /> treated ground water will be reinjected at the ground water <br /> reinjection system. <br /> Table 4-4 summarizes the VOC effluent concentrations in ground water <br /> for each of these ground water treatment mechanisms. <br /> TABLE 4-4 <br /> Extracted Ground Water Treatment Objectives <br /> Constituent Untreated Ground Expected Expected Expected <br /> Water Influent Concentration Concentration Concentration <br /> Concentration following Stripping at following following Carbon <br /> (dual phase extraction the Extraction Tube Processing through Polish* <br /> well/plume margin (dual phase extraction the Multi-Stage (Reinjection <br /> well contribution) well contribution only) Diffuser Concentration) <br /> (ug/L (ug/L) (ug/L) (ug/L) <br /> cis 1,2-Dichloroethene 87.6/8.3 8.8 1.3 <5 <br /> 1,1-Dichloroethane 42.3/16.0 4.2 1.2 <5 <br /> Vinyl Chloride 103.4/2.3 10.3 0.01 <0.5 <br /> Benzene 2.3/0 0.23 0.02 <1.0 <br /> Total HVOCs ?53.4/39.1 25.3 4.5 <5 <br /> Total AVOCs 15.9/0 1 1.6 1.1 <5 <br /> *Effluent concentrations of VOCs in treated ground water will be less than the maximum <br /> contaminant level(MCL) indicated. <br /> 4-9 <br />