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"SOMA <br /> Working To Restore Nature <br /> or 57% of the well loss. Screen diameter, slot size and filter pack placement are probably the <br /> primary factors of this inefficiency <br /> Capture Zone Radius <br /> The radius of plume capture for a hypothetical extraction well constructed as the existing <br /> monitoring wells was evaluated using the data obtained from the pumping tests. The minimum <br /> steady state limit of capture (downgradient) can be estimated using Darcy's law. The <br /> downgradient limit of capture occurs at the distance from the pumping well where the induced <br /> velocity/gradient toward the pumping well equals the natural velocity/gradient in the opposite <br /> direction. The formula is <br /> ' rQ <br /> = /T12-ir <br /> ' where: <br /> 3 <br /> r _ downgradient capture radius in feet <br /> Q extraction rate in gpd <br /> T = transmissivity m gpd/ft <br /> I = natural groundwater gradient <br /> The mechanics of small diameter pumps limit extraction to approximately 3 gpm in a 2-inch <br /> diameter well. For an extraction well at this site pumping 3 gallons per minute(4320 gpd), with <br /> i <br /> an aquifer transmissivity of 11,300 gpd/ft and a natural groundwater gradient of approximately <br /> 0.003 ft/ft, the downgradient limit of capture would be 20 feet This would not be acceptable, <br /> ' either in terms of hydraulic control or remediation <br /> ' Feasibility of establishing hydraulic control: <br /> The terms of the above equation can be rearranged to solve for Q in order to determine the <br /> ' pumping rate that would be required to achieve the desired results: <br /> ' Q = rT12-r <br /> ISMIUWOMWAP-07%DRF 11 <br />