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f <br /> CLEARWATER <br /> c rt O LJ P, [ N C <br /> requirements All data is recorded in a written log by the vapor extraction test <br /> technician Depending on equipment used, some data is also recorded in computer <br /> generated printouts or unto electronic data logs <br /> DATA EVALUATION <br /> Radius of Influence <br /> The test is performed at several pressure/flow rate combinations (steps) to <br /> determine the optimal vacuum and flow rate needed to obtain a sufficient radius of <br /> influence for one well The radius of influence will be determined as the radius <br /> from the extraction well to a distance from the well where the measured vacuum is <br /> one percent of the applied vacuum (Buscheck & Peargin, 1991) Alternatively, the <br /> radius of influence may be defined as the estimated distance from the extraction <br /> well where vacuums are not less than 01 inches of water (Johnson, 1994) This <br /> radius of influence is assumed to approximate the maximum distance from the <br /> extraction well at which contaminated soil will be remediated through <br /> volatilization Although there are limitations inherent in_determuung the radius <br /> of influence based on pressure distributions (Johnson & Ettinger, 1994), this method <br /> is generally accepted as a screening technique The radius of influence may not <br /> necessarily increase significantly beyond a certain flow rate and vacuum Therefore, <br /> the optimal vacuum and flow rate will be based on blower efficiency relative to the <br /> area of influence and may not necessarily be the maximum vacuum and flow rate <br /> This evaluation will be determined graphically by plotting the vacuums observed at <br /> each monitoring point versus the distance of the monitoring point from the <br /> textraction well for each step test Semi-log paper may be used to obtain a straight <br /> line fit through the data for each applied flow rate and vacuum In addition, the <br /> applied flow rates and corresponding vacuums for each test will be plotted on linear <br /> paper to evaluate the effect of vacuum on flow rates <br /> Permeability <br />' Data collected from several monitoring points during each test will be evaluated to <br /> determine the permeability of the formation following the method outlined by P C <br /> Johnson, et al (1990) based on the flow rate and transient pressure distribution data <br /> Two different permeability calculations presented by Johnson, et al (1990) and <br /> summarized by Dupont (1993) can be performed depending on site parameters The <br /> first calculation assumes radial flow with no vertical leakage and relatively long <br /> screens (>10 ft) The second calculation assumes some vertical flow, shallow soil <br /> contamination and relatively short well screens (c10 ft) For a derivation and <br /> presentation of the calculations refer to the original references <br />' Soil Vapor Extraction Test Protocols Page 3 of 5 December 16,1994 <br />