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4.1 Groundwater Extraction 4.0 FINDINGS Due to the limited water column in MW-2, a maximum drawdown of only 4 feet was possible The application of a vacuum at the well head did increase well recharge The percent increase in recharge was not measured The maximum drawdown of 4 feet was maintained throughout the groundwater extraction test During pumping, groundwater depth in MW-6 decreased by 0 12 feet The vacuum applied to MW-2 may have had an effect on the depth-to-groundwater, the lateral influence of this vacuum was not investigated Volatile organics were detected with the PID from the blower output at concentrations from ' 230 ppm to 335 ppm TPH as gasoline was detected in the air sainple collected from MW-2 at a concentration of 3,600 molar ppm The analytical results aie summarized on Table 1 The laboratory report and chain-of-custody are included in Appendix B 4.2 Vapor Extraction No organic vapors were detected fioin the blower output with the PID during extraction No hydroeaibon odors were noticed during extraction Xylene wars detected in the 15-minute sample at a concentration of 0 088 ppin TPH as gasoline and xylene were detected in the 90-minute sample at 10 ppm and 026 ppm, respectively The analytical results are summarized on Table 1 The laboratory report and chain-of-custody are included in Appendix B TABLE 1 ANALYTICAL RESULTS OF AIR SAMPLES Lockeford Beacon molar ppin Sample Sample TPH as Benzene Toluene Ethyl- Total I D Location gasoline benzene Xylenes 1 MW-2 3,600 25 40 51 75 2 UST piping ND ND ND ND 0 088 3 UST piping 10 ND ND ND 026 4.3 Relative Groundwat.-r Elevation and Gradient The relative elevation of groundwater in each well was calculated by subtracting the depth to water from the surveyed casing elevation (Table 2) All wells were surveyed relative to as'..'"' d i S< 'K t��w B-0m,ft aeas 7