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r <br /> `kll <br /> { <br /> Page 11 <br /> February 6, 1990 <br /> Job No. 211-71-6 <br /> of 0.024 Teet per foot and the average aquifer parameters determined from the aquifer test data presented earlier <br /> in this report. <br /> . TABLE R <br /> PREDICTED CAPTURE ZONE DIMENSIONS <br /> OF RECOVERY WELL RW-1 <br /> Discharge Dcwa�-Gradient ':Crus.,-Gradient <br /> H RaCapture te. Capture Zone r Zone <br /> ,.a .. -. <br /> {g> } Radius(ft) Radius; it} ,. <br /> 4' 220 BSO <br /> 160 520 <br /> 110 340 . <br /> The capture zone dimensions listed in Table B are based on the aquifer araine ars determined from the aqu der <br /> H test`Pnalyzed in this report, isotropic and homogeneous aquifer characteristics, and a ground-water gradient ' <br /> similar to that shown in Figure 2. <br /> CONCLUSIONS AND RECOMMENDATIONS <br /> The drawdown experienced in recovery well RW-1(13 feet)during the aquifer tes:run at a discharge rate of 4 <br /> gpm was very close to what is expected to be the maximum allowable drawdow:i for the well. Drawdown within <br /> the recovery well at a discharge rate of 3 gpm (over a 24-hour period)is predicted to be approximately 9.5 feet. <br /> _ Therefore,assuming the aquifer is isotropic and homogeneous and is lateraly"extensive",Du Pont recommends <br /> a long-term discharge rate of 3 gpm for recovery well RW-1 and other recovery wells of similar construction <br /> completed in the same shallow aquifer. <br /> At a discharge rate of 3 gpm, the predicted dow4—,gladient and cross-gradient radii of capture are predictc.i to <br /> be-160 feet and 520 feet,respectively. Based on these capture zone dimensions-it is recommended that at least <br /> one additional recovery well of simiiar design to well RW-1 lx_installed at the location (.riangle) shown on <br /> Figure 5, Well Location and Benzene Isopleth Map,'for the purpose of collecting the shallow&'ound;'water <br /> a known to contain detectable-'evels of benzene at the subject site, <br /> t <br /> Dn Pani;Environmental Services <br /> - <br /> METRIC <br /> f <br />