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i <br /> i <br /> ITemporary Vacuum Extraction Probes and Existing <br /> Groundwater Monitoring Wells <br /> I Six temporary vacuum extraction probes will be driven <br /> pneumatically into the soil at the locations specified on <br /> Figure 1. The perforations in the probes will be located at <br /> a depth of 20 to 35 feet below grade. Groundwater <br /> monitoring wells MW-3 and MW-4 will be incorporated into the <br /> remediation system, also. Specifications for the <br /> groundwater monitoring well retrofit and the temporary <br /> vacuum extraction probes are given in Details A-1 and A--2 , <br /> respectively. <br /> I The temporary vacuum extraction probes and groundwater <br /> monitoring wells will serve as extraction points. A vacuum <br /> will be applied to an extraction point to volatilize <br /> I hydrocarbon products in the soil. The soil gas will flow <br /> from the soil through the perforations in the probes or the <br /> slotted screening in the extraction wells. The effective <br /> capture radii expected from the temporary vacuum extraction <br /> I probes and groundwater monitoring wells (vacuum extraction <br /> wells) are given in Figures 3 and 4 , respectively. <br /> Trenching and Piping <br /> The extracted soil gases will be transported through <br /> underground piping. Soil gases will be extracted from the <br /> probes and wells to a manifold, then from the manifold to <br /> the system equipment. The system underground piping will be <br /> installed in shallow trenches and avoid existing utilities. <br /> Specifications for common trenches installed in concrete and <br /> asphalt and the mainline trench are given in Details A-3 , <br /> A-5, and A-4 , respectively. <br /> IManifold <br /> The manifold box consists of 10 valves and sampling ports <br /> that control individual extraction points (Detail A-5) . The <br /> valves located in the manifold box will be either open or <br /> closed, depending on whether or not an extraction point is <br /> I to be utilized. This will expedite the remedial effort and <br /> i minimize the cost per pound of hydrocarbon abatement. <br /> IEquipment <br /> The system equipment will include a pumping unit, a <br /> catalytic incinerator, and an accumulator/water knockout. <br /> The system equipment will be located at the northeast corner <br /> of the former station building (Figure 1) . Extracted soil <br /> I <br /> I <br />