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1 <br /> Geo(�gftalTeckxccslx� Page 15 <br /> Dual Phase Extraction Pilot Test Report <br /> Project No 662 2 <br /> February 22,2005 <br /> 1 <br /> GTI calculated the mass balance for TPH-G removed during the test using the above average <br /> ' TPH-G value for EW-I/EW-2 samples and the value of 32,250 gallons of extracted <br /> groundwater The results are tabulated in Table 8 Mass Balance Calculations Groundwater <br /> Extraction The disposal of 32,250 gallons of water from the extraction wells during the one <br /> ' week test resulted in the removal of approximately 0 03 kg or 0 08 gallons of TPH-G <br /> The December 6 - 10, 2004, groundwater laboratory analytical data were submitted <br /> ' electronically to GeoTracker as required under AB2886 on February 14, 2005 (Confirmation <br /> #'s 8070687055 and 2807940840) <br /> 7.0 CONCLUSIONS & RECONVEWENDATIONS <br /> Based on our interpretation of the data collected over the course of this subsurface <br /> investigation, GTI have reached several conclusions These conclusions are based on the <br /> ' premise that the data we considered, although incomplete, are representative of actual site <br /> conditions We acknowledge that there may be undiscovered conditions, which would upon <br /> their consideration, change our interpretation and thus our conclusions <br /> The following conclusions are made <br /> 1 Soil vapor extraction is a viable technology for reducing contaminant concentrations <br /> ' in the subsurface at the site The pilot test demonstrated that up to 0 1 inches of water <br /> vacuum could be achieved at a distance of 58 feet from the extraction point (the <br /> distance from extraction well EW-2 to monitoring well MW-2) <br /> ' 2 GTI estimated that approximately 0 3 lbs or 0 05 gallons of petroleum hydrocarbons <br /> were removed by vapor extraction during the week long test This amount includes <br /> hydrocarbons removed from groundwater during the liquid ring pump separation <br /> ' process As shown in Table 3, when extraction vacuum was applied to EW-1, the <br /> amount of vapor contaminants removed from shallow well EW-2 dropped <br /> significantly with MTBE values dropping to non-detect levels This suggests that <br /> ' operating high vacuum soil vapor extraction from EW-2 should occur independently <br /> of pumping deeper groundwater to achieve maximum vapor extraction Using a <br /> ' submersible pump in well EW-1 would alleviate the need to divert extraction vacuum <br /> from shallow well EW-2 <br /> 3 A sustained pumping rate of over 5 gpm was achieved in wells EW-1 and EW-2 for <br /> ' several days accounting for the extraction of over 32,000 gallons of groundwater <br /> Higher pumping rates were possible but were not maintained during the test due to the <br /> j lack of water storage capacity This demonstrates that the site's soils are conducive to <br /> ' groundwater extraction technology If the pumping was continued then the drawdown <br /> would produce a cone of depression further exposing soil to be influenced by vapor <br /> extraction <br />