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Evaluation of Potential Well Impacts From <br />The Proposed Nix Property Sand and Gravel Operation <br />Using a spreadsheet, an iterative process was used to assign a pumping rate (Q) that would create <br />a drawdown equivalent to the maximum elevation difference (described previously using <br />September 14, 2001 data) at the upgradient side of each mining azea after a period of 365 days <br />(t). Using this assumed pumping rate and a period of one yeaz, WWE calculated the drawdown <br />effect (i.e., the difference between the pre-mining groundwater surface and the post-mining <br />groundwater surface) at various upgradient well locations. Table 4 is the spreadsheet used to <br />evaluate potential reductions in groundwater levels at various distances from Mine Areas 1, 3, 4 <br />and 5. <br />Using this data, it can be demonstrated that the greatest potential reduction in groundwater level <br />resulting from wet mining the Nix property is to the wells located closest to the excavated pits. <br />Review of Sheet 1 shows that the Mayer irrigation well (identified as Well No. 38 on Sheet 1 and <br />on Table 1) is located approximately 300 feet away from Mine Area 3. However, its location is <br />near the middle of Mine Area 3 and, due to lake leveling, will likely see no more than 1.2 feet of <br />groundwater level change. More importantly, the presence of an unlined pit in such close <br />proximity to the well will provide a nearly unlimited recharge source, thus offsetting a potential <br />reduction in the saturated thickness neaz the well. <br />The Kurtz irrigation well (Well No. 35 on Sheet 1) is located 300 feet downgradient of Mine <br />Area 5. Because of its location downgradient of the excavated pit, this well will likely benefit <br />from an elevated groundwater surface relative to the pre-mining groundwater surface elevation <br />(i.e., an increased saturated thickness). <br />In a similaz fashion, an evaluation of groundwater level changes has been conducted on each well <br />identified in Table 2. Table 5 has been prepazed to identify the neazest pit location to each of the <br />wells, the maximum elevation difference at the upgradient end of the pit due to lake leveling and <br />the resulting estimated decrease in groundwater level anticipated at each well location based on <br />September 14, 2001 conditions. In all cases, drawdown effects on wells greater than 600 feet <br />from the respective pits aze estimated to be less than 1 foot. <br />011-074.000 Wright Water Engineers, Inc. Page 8 <br />November 2001 <br />