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ON <br />, x <br /> Coca-Cola Enterprises-West <br /> USTEC Job No.94054.03 <br /> s The extraction of air from the unsaturated zone will reduce the concentrations of petroleum <br /> hydrocarbons in the soil. As the hydrocarbon containing vapor is removed,it is replaced by sail <br /> j.; <br /> vapor from outside the affected area. The hydrocarbons adsorbed in the soil will volatilize and <br /> diffuse into the soil vapor, which is in turn removed by the applied vacuum. 1fius, the <br /> 3 <br /> concentration of volatile hydrocarbons is reduced over time. In addition,the oxygen introduced <br /> 3 <br /> in the hydrocarbon contaminated unsaturated zone will also promote natural biodegradation of <br /> the hydrocarbons. <br /> t <br /> � ;4 <br /> i <br /> Following in of the VES wells,a final vapor extraction test will be performed using the <br /> R existing monitoring wells as test points. The conclusions made from data recovered from this rxPPu'i' I ti <br /> t <br /> test will be used to review the computer analysis resented in Section 7.1. Based an the radius <br /> of influence indicated by the final vapor extraction pilot test and USTEC's experience gained on <br /> systems of this type in similar soils, we anticipate a flow rate of about 20 to 10 cfm per well. <br /> s <br /> -. 5.3 VAPOR EXTRACTION SYSTEM <br /> # The four vapor extraction wells(VEW-1 through VEW-4)which were constnzcteci to perform the <br /> 1 initial vapor extraction pilot tests will be incorporated into the proposed vapor extraction system <br /> ' shown on Figure 15. <br /> - The construction of the four additional vapor extraction wells will be similar to that shown on <br /> Figure 5. Three of the vapor extraction wells will be completed to a depth of 45 feet bgs with <br /> a screened interval from 8 to 45 feet bgs. The fourth well will be completed to a depth of 68 feet <br /> — bgs with a screened interval from 8 to 68 feet bgs. <br /> The vapor extraction wells will be constructed of 4-inch diameter PVC blank casing and screen. <br /> ' The screen will have an 0.010-inch slot size. A sand pack of Number 3 Monterey silica sand will <br /> be added to a height of about 2 feet above the screened interval. A 2-foot thick bentonite seal <br /> will be placed above the sand pack and hydrated with about 15 gallons of distilled water. <br /> i fill the remainder of the annular space to the surface. At the <br /> Cement grout will be used to <br /> -- --19 -- <br /> i <br /> IS <br /> , o <br /> y <br />