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J^ <br /> s <br /> gig <br /> c I <br /> provide the basis of the proposed system. The proposed vapor <br /> -� extraction system will utilize the three existing vadose wells (VP1, <br /> VP2, and VP3) in addition to a fourth well which will be installed at <br /> the location shown on Figure 9. The existing wells are screened from <br /> approximately 5 to 30 feet below grade as indicated on the lithologic <br /> lags (Appendix I) . The fourth well will be completed in a similar <br /> manner. <br /> T^, affect the area of concern, approximately 50 cfm of soil vapor <br /> 7 will be extracted from each of the three existing wells creating a <br /> radius of influence of approximately 28 feet from each extraction <br /> r- well. This extraction rate is based on a 5 month operW on period. <br /> It is anticipated that the extraction rate and radius of .influence <br /> from the fourth will be somewhat less than the existing wells. <br /> Because the long term performance of a system cannot be completely <br /> predicted from short term testing, careful monitoring will be <br /> performed in order to assess the need for operational modifications <br /> M and/or the installation of additional extraction wells. The <br /> predicted area of influence for the vapor extraction system is shown <br /> on Figure 9. <br /> i.: The influent pair stream from the vapor extraction wells will, be <br /> routed to the treatment compound within the below grade piping <br /> system. The tzeatment compound will house all of the above grade <br /> portion of the xemediation system and will be located behind the . <br /> existing service station building (Figure 9) . <br /> r <br /> ` Four alternatives for the control of off-gas emissions from the vapor <br /> `-' extraction system were evaluator. These are (1) thermal. oxidation, <br /> (2) catalytic oxidation, (3) carbon adsorption, and (4) the <br /> destruction by internal combustion (IC) engine. Based on the <br /> relatively low levels of hydrocarbons in the vapor samples collected <br /> during the -Pilot test, the low flowrates required, and the relatively <br /> _high permeabilities,_ a^combination of vapor phase carbon and an IC <br /> engine are proposed. <br /> Kober Paint Property — 475 - <br /> MP0591.w 12 .. <br />