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Mr. Phil Dawson <br /> August 26, 2009 <br /> Page 4 <br /> Chemical and hydraulic data obtained during the two pumping tests that show <br /> small radii of influence and low sustainable yields in the NWC. <br /> Hydraulic data from the pumping test indicates an average groundwater velocity of <br /> approximately one foot per day, which means groundwater moved about 30 feet during <br /> the test. Dieldrin analyses performed throughout the entire test showed that <br /> concentrations in observation wells did not decline, proving that dieldrin was moving in <br /> from beyond those monitoring wells and that the radius of influence extended to beyond <br /> 30 feet. <br /> Hydraulic data also demonstrates that the cones of depression at the end of the <br /> pumping tests were elongated ovals, not circles, indicating heterogeneous and <br /> anisotropic conditions. The State has prepared and attached a map figure showing the <br /> elongated ovals. These oval-shaped cones of depression are supported by the fact that <br /> wells located at approximately the same distance from the pumping wells had different <br /> draw downs while other wells having approximately the same drawdown were at <br /> different distances from the pumping wells. These observations are consistent with an <br /> aquifer containing long, narrow preferential pathways, such as the interconnected <br /> stream channels predicted by the State's site conceptual model described to DLA <br /> previously. <br /> The radius of influence (ROI) calculation performed by DLA appears to have <br /> significantly under predicted the actual ROI due to assumptions made during <br /> calculation. One of the calculation parameters involves well efficiency which does not <br /> appear to have adequately considered aquifer storage coefficient conversion. It is far <br /> more likely that the wells are more inefficient and have a much higher radius of <br /> influence than was calculated. <br /> Figures 3-5 and 3-6 of the aquifer pump test representing the distance-drawdown plots <br /> for the aquifer pump test presented an unrealistic 100 percent well efficiency, and never <br /> presented the other observation monitoring wells influenced by the pumping such as <br /> LM174AU or LM140AU as points on the curve, even though hydraulic data <br /> demonstrated the communication between the wells. The observation wells presented <br /> on the distance draw down curves are located in close proximity to the pumping well <br /> and bias the ROI as a much smaller value than the observed data and observation wells <br /> data demonstrates. <br /> DLA contends that the aquifer has low sustainable yields. However, the significance of <br /> the increase in drawdown late in the second test was dismissed by DLA, although <br /> acknowledged. The increase in drawdown was caused by the aquifer's transition F,om <br />