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vertical hvdraulic conductivity of 33 to 100, or an approximately 1 to 2 orders of magnitude • difference, which is consistent with the stratified sediments of silt and clay encountered at this site + Zone of Capture An estimate of the steady state downgradient limit of an extraction well capture zone can be made using the following equation r, = Q/2xTi, where r. = limit of capture zone downgradient of a pumping test well (point where pumping induced ground-water velocity equals the natural velocity), Q = pumping rate T = average transmissivity i = average ground-water gradient magnitude However, for this site the groundwater gradient is highly irregular and has shifted in both magnitude and direction Therefore calculation of a steady state capture zone is not valid For purposes of evaluating remediation feasibility an extremely conservative approach (greatly underestimates potential capture zone) is to use the steepest observed gradient moving away from the tank area This is the northeast gradient with magnitude of 04 calculated from the July 23, 1990 monitoring event. Using this calculated gradient, the estimated maximum sustainable extraction rate of 3 5 gpm from well RW-1 and the average value of T based on data collected during the pumping test, ry = 12 feet This value must be considered very conservative and it is more likely that the gradient direction reversals result in an average gradient over the hydrologic cycle that is relatively flat This would result in a rather large potential capture zone Longer term static monitoring at the site would be needed to define the capture zone more precisely Conclusions The analyses of pumping test data from the site yields the following conclusions o The water-bearing zone from approximately 48 to 60 feet below grade is heterogeneous, . anisotropic, and unconfined