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Hydro&eo Consultants 8.0 REMEDIAL ACTION PLAN Based on the available data, vapor extraction and groundwater extraction will be ' considered the primary methodology for remediation of TPHg, BTEX, and MTBE in groundwater and soil at the Site Based on HydroGeo Consultants experience, this treatment method offers the quickest and the most cost-effective means to reduce TPHg, BTEX, and MTBE from groundwater and soil, in addition this methodology was previously proposed in a earlier Corrective Action Plan that was prepared for the Site The strategy of remediation will be to concentrate contaminant removal efforts in the ' area of greatest contamination surrounding the previous tank cluster The tentative proposed system will include groundwater extraction through pumping from wells MW-5 and MW-2 (Figure 4) Vapor extraction will continue to be performed ' simultaneously from these wells and the other vapor extraction wells at the Site The groundwater extraction wells will consist of the pump well that was tested (MW-5) ' and the well at the downgradient edge of the dissolved phase plume (MW-2), both of these wells contain elevated levels of dissolved gasoline constituents (Figure 4) Pneumatic pumps will be used to extract groundwater from each extraction well and the pump controller will be placed in the remediation compound The pump placed in MW- 5 will need to be a 1 5-inch diameter pump capable of producing between 1-2 gallons per minute and should be set at a depth of approximately 55 feet below grade This pump should be operated at approximately 1 6 gallons per minute The pump for MW-2 should be a 2-inch diameter-pump capable of pumping 0 2-1 gallon per minute and should be set at a depth of 53 feet below grade The pump should be operated at vo approximately 0 5 gallons per minute if possible, but may need to be adjusted depending on the yield of this well which is expected to be much lower than MW-5 ' since it does not intersect the sandy layer at 65-70 feet in depth Groundwater will be discharged back to-the-treatment compound from each-wellwith-'/z inch-flexible.-- discharge line for MW-5 and MW-2 The discharges lines will be placed inside the - ---- = -existing-PVC conduit-(or vapor extraction-line) that is present-leading back to-the — treatment compound or a separate conduit will be installed if necessary (Figure 4) The discharge will pass into the low profile air stripper(Figure 4) The air stripper will be designed based on the inlet concentrations (Table 7) and system flow rate of 2-3 ' gallons per minute The treated discharge will then pass through two 1,000-pound virgin carbon vessels for polishing prior to discharge to the sanitary sewer or storm ' drain under proper permit(Figure 4) A flow meter totalizer will be installed between the last carbon vessel and the discharge point The off-gas from the air stripper will be routed back into the influent of the thermal oxidizer for treatment (Figure 4) _ 1 9.0 REFERENCES Cooper, H H and C E Jacob 1946 A generalized graphical method for evaluating formation constants and summarizing well field history,Am Geophys Union ' Trans , Vol 27, pp 526-534 r --Page 14 — -- --_ --- —__ _ -- __ _ TOC#171 Aquifer Test and RAP Rpt _ _