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Vapor Extraction Test Report <br /> Former Thrifty Oil Service Station # 172 <br /> September 14, 1995 <br /> Test Well VW-B (screened 5 to 48 feet below grade): <br /> • Soil transrrussibihty to air value (kh/µ): 5,478 d-ft/cp - <br /> 0 Vertical extraction interval (h): 48 feet <br /> • Soil permeability to air (k): 2.02 darty <br />' Test Well VW-C (screened 10 to 45 feet below grade): <br /> • Soil transmissibility to air value (kh/µ): 16,287 d-ft/cp <br /> • Vertical extraction interval (h): 45 feet <br /> • Soil permeability to air (k): 6.54 darty <br /> The individual values calculated using each well pair are reported at the end of Appendix D, and <br /> the average soil parameters derived from the steady-state test are summarized in Table 2. <br /> 4.3 EFFECTIVE RADIUS-OF-INFLUENCE <br /> The estimated ERI (distance from the extraction well at which a pressure drawdown of 0.10 in. <br /> H2O is anticipated durmg extraction, resulting in air flow through the subsurface) is computed <br /> using the average soil transmissibility values and Equation 6 in Appendix D. In addition, the <br /> ERI values were estimated graphically from Figure 2. The graphical solution for average ERI <br /> is preferred over the Darcy solution in this case because the observation wells' vacuum responses <br /> were low. The average estimated ERI values for each test well are as follows: <br /> Test Well VW-A: <br /> • Flow rate: 16.6 schn <br /> ERI (Darcy): 30 feet <br />' • ERI (graphically): 34 feet <br /> Test Well VW-B: <br /> • Flow rate: 17.1 schn <br /> • ERI (Darcy): 25 feet <br /> ERI (graphically): 36 feet <br /> Test Well VW-C: <br /> • Flow rate: 16.3 scfm <br /> • ERI (Darcy): 31 feet <br /> • ERI (graphically): 40 feet . <br />' 4 <br />