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s <br /> Since some analytic methods require consistent data units, the field vacuum responses in <br /> inches of water were converted to equivalent vacuum in feet of air. This was accomplished <br /> by noting that the density of water is approximately 833 times that of air. Field extraction <br /> test data are presented in Appendix A. <br /> TABLE 2 <br /> VADOSE ZONE AIR PARAMETERS <br /> EXTRACTION WELL MW-10 <br /> Observation Well Transmissivity Storativity r/B <br /> (fooe per minute) (Dimensionless) (Dimensionless) <br /> MW-1 021 6 x 10-3 0 365 <br /> MW-2 65 x 10 -2 85 x 10' 06 <br /> MW-3 0 165 33 x 10' 018 <br /> MW-4 56 x 10 -2 69 x 10-4 07 <br /> DATA ANALYSIS <br /> The pressure response data obtained from MW-1, MW-2, MW-3, and MW-4 during the <br /> constant rate extraction test were analyzed using the Hantush method. This method <br /> assumes air leakage from the ground surface and no air storage. This analysis method <br /> permits the calculation of the soil transmusivity to air (T), storativity (S), and the <br /> dimensionless parameter r/B. <br /> VAPOR EXTRACTION TEST RESULTS <br /> Vapor extraction data suggest the vadose zone has an air transmissivity ranging from <br /> approximately 5 6 x 10-2 to 0.21 feet squared per minute (ft'/min), storage values ranging <br /> between 3.3 x 10' to 6 x 10'3, and r/B values ranging from 0 18 to 0.7. <br /> Effective Radius of Influence <br /> Using the estimated average air transrnissivlty values, the effective radius of influence (ERI) <br /> is estimated at approximately 130 The ERI is calculated as the distance at which a pressure <br /> response of 010 inches of water is expected to prevail, resulting in air flow through the <br /> subsurface. The calculation assumes achievable flow rates of approximately 48 chn from a <br /> single vapor extraction well <br /> 4 <br />