Laserfiche WebLink
Evaluation of Potential Impacts <br />From The Proposed Nix Property Sand and Gravel Operation <br />On Shallow Groundwater Levels, Water Wells and Wetlands <br />The evaluation conducted by David Cooper in his letter of July 16, 2001 was based on dry <br />mining of the site with relatively large reductions in the water table. The changes in the water <br />table from wet mining, as is now proposed, will be much smaller and would not result in lazge- <br />scale dewatering of the wetland. <br />5.0 CONCLUSIONS <br />Because of early concern with dry mining expressed by adjoining property owners and WWE's <br />initial evaluation of this alternative, Owens Bros. made the decision to use wet mining methods <br />to develop this resource. As such, W WE has conducted apost-mining evaluation of the potential <br />well and wetland impacts from the proposed wet mining of the Nix Sand and Gravel Operation. <br />The conclusions reached as a result of this evaluation are as follows. <br />5.1 Groundwater Levels and Water Wells <br />• Impacts to neighboring wells will occur from the leveling effects imparted on the sloping, <br />pre-mining groundwater surface resulting from the extraction of sand and gravel from below <br />the groundwater surface. <br />• This leveling effect will create post-mining lake surface elevations 0.5 to 3.0 feet lower than <br />the pre-mining groundwater surface at the upgradient end of Mine Areas 1, 2, 3 and 6 based <br />on September 14, 2001 groundwater surface observations. <br />• Using the Theis non-equilibrium equation, the lake leveling impacts (i.e., reduction in <br />available saturated thickness) to upgradient well owners within 600 feet of the mining azeas <br />can be shown to be generally less than 1 foot, with many wells projected to experience less <br />than 0.5 feet of reduced saturated thickness. <br />• Using the Theis non-equilibrium equation, it can be shown that a typical IS-gpm domestic <br />well and a 1,000-gpm imgation well create 0.2 and 10.6 feet of drawdown, respectively, in <br />the aquifer at a distance 1 foot away from the pumping well if pumped continuously for 365 <br />days. An increased reduction in saturated thickness of up to 1 foot at these representative <br />011-074.000 Wright Water Engineers, Inc. Page 14 <br />April 2002 <br />