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3.1 Mining Phase I <br />For the Phase I pit dewatering analysis, a circular pit with a radius of 1,200 feet was used for the <br />almost square pit. Based on available information and parameter assumptions, the unobstructed <br />radius of influence was estimated to extend approximately 3,300 feet beyond the pit wall <br />(Figure 3) with dewatering flows from the pit of almost 2,900 gallons per minute. Drawdown of <br />the alluvial groundwater elevation is illustrated in Figure 4 and the spreadsheet analysis results <br />are included in Appendix B. <br />As discussed above, the drawdown affects will be reduced by Arkansas River recharge and <br />obstructions on the west side of the mine site. The result of these affects on the radius of <br />influence has been estimated in Figure 3. Additionally, the drawdown affects north of the site <br />will only extend to the alluvium boundary (Figure 3). Although Figure 3 and Figure 4 present <br />estimates of potential dewatering impacts, alluvial groundwater elevation monitoring is <br />recommended to evaluate actual impacts. <br />Figure 4. Phase I Dewatering Curve <br />m 25 <br />m <br />N 20 <br />m <br />c <br />Y <br />Z <br />15 <br />® 10 <br />H <br />5 <br />E <br />7 <br />•5 0 -- <br />3 0 2,000 4.000 6.000 8,000 <br />Q <br />Distance from Edge of Pit (feet) <br />3.2 Mining Phase II <br />Potential dewatering impacts were not calculated for Phase I1 of the mining operation. Phase II <br />mining operations and dewatering will begin when mining in Phase I is complete and lining of <br />the Phase I pit has begun. Phase I pit dewatering will continue as lining and other reclamation <br />activities progress. Therefore, the affects of Phase II pit dewatering will be impeded or <br />overshadowed by Phase I reclamation activities. Similar to Phase I mining, continuous recharge <br />from the river will also influence the affects of Phase II dewatering. Impacts from dewatering <br />will not extend south of the river, and the radius of influence will be reduced immediately north <br />of the river due to the increased recharge. With the drawdown obstructions north and south of <br />(blue eorth Page 8 of 11 <br />SOLUTIONS <br />