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S' <br /> a <br /> ' A <br /> NI <br /> Temporary Vacuum Extraction Probes and Existing <br /> Groundwater Monitoring Wells <br /> 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 MST-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 /> 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 i <br /> 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 /> u <br /> 1 capture radii expected from the temporary vacuum extraction j <br /> 1 probes: and groundwater monitoring wells (vacuum extraction i <br /> j wells) are given in Figures 3 and 4, respectively. <br /> I ; <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 /> Manifold <br /> a The manifold box consists of 10 valves and sampling ports <br /> that_control__individual.extraction points__(Detail_A-6) .__. 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 /> r <br /> to be utilized. This will expedite the -remedial effort and <br /> minimize :the cost per pound of hydrocarbon abatement. <br /> Equipment <br /> The system equipment will include a pumping unit, a <br /> catalytic incinerator, and an accumulator/water knockout. <br /> Im <br /> The system equipment will be located at -the northeast earner <br /> of the former station building (Figure 1) . ]Extracted scil <br /> 3 <br /> l <br /> t <br /> s <br /> c� <br />