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Pilot Testing Report and Conceptual Corrective Action Plan July 15, 1994 Manna Pro, 4004 South EI Dorado, Stockton, CA 24 63 Groundwater Pumping and High Vacuum Extraction System ' The conceptual remedial design focuses on an area 330 feet by 370 feet as shown on Figure 11 The treatment technology recommended for the area is groundwater pumping and HVE The results from the HVE pilot test indicate that groundwater pumping and HVE will be most effective in removing adsorbed- and dissolved-phase hydrocarbons present in the saturated and unsaturated 1 zone 6.31 Design Basis IThe HVE design was based on the results of the Vent-ROI model, using field data collected during pilot test activities The primary factor impacting the effectiveness of a vapor extraction system is 1 the volume of air passing through the vadose zone volatilizing adsorbed hydrocarbons As shown in the mass estimates (Section 4 1 2), the majority of the hydrocarbon mass is present in the adsorbed ' phase The Vent-ROI model accounts for lithologic factors and conservatively estimates the effective radius that sod vapor may be extracted from a single extraction well By overlapping effective radii of influence, a is possible to address large areas of hydrocarbon impact The well spacing and layout presented is expected to adequately remediate the area of impact at the Manna Pro facility To ensure that groundwater with dissolved hydrocarbons does not continue to migrate from currently impacted areas, a negative net groundwater flow across these areas must be induced This implies that the rate of groundwater pumping and treating of a groundwater remediation system must match or exceed the rate of groundwater flow across the hydrocarbon impacted area of the property under static water table conditions The groundwater extraction well network design was conservatively based on the results of the aquifer test (i e , using groundwater extraction alone) Although, combined groundwater extraction and HVE is expected to produce more favorable results 6 3 2 Conceptual Corrective Action Plan The conceptual Corrective Action Plan has been prepared to address hydrocarbons In the area of concern The conceptual system design is based on the results of the aquifer test and the ' combined groundwater pumping and HVE pilot test The pilot test results indicate that an HVE extraction point may achieve a radius of influence of 18 feet at 15 scfm flow rate and 148 5 inches of water vacuum per point In addition, 3 groundwater pumping wells may achieve a combined ' 2819RO34 070 GROUNDWATER TECHNOLOGY, INC