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• Removal of wells and Ponds by Mining. There are no righted or unrighted walls within the <br />area of proposed nti nlnq disturbance. Thus, there is no potential for any Smpacta to wells <br />from the mining construction activities. Two unregistered stock ponds 1500 and 2800 feet <br />upstream of Pond 011) exist In areas of proposed mining disturbance on land owned by <br />Seneca Coal Company Isee Exhibit 16-1, Tab 16). SCC does not plan to replace these ponds. <br />PSt Pumpage Drawdown Effects on Adjacent Water Users. Analysis of pit pumpage [ates and <br />estimated drawdown distances was performed for the Overburden and the Wadge Coal aquifers <br />(see Ground Water Inflows to PS is and Drawdowna). A summary of the pun~age rates and <br />drawdown distances for the two aquifers is presented Sn Table 17-4. A map of one-foot <br />drawdown distances for both aquifers la contained in Exhibit 17-1. The drawdown contour <br />map indicates [hat the predicted overburden one-foot drawdown contour Se located within <br />the Yoast Mine leasehold area. The estimated one-foot drawdown contour for the Wadge Coal <br />is located less than 120 feet beyond the pi[ excavation boundary and Se situated well <br />within the Yoaet leasehold. Exhibit i6-1 depicts the location of righted and unrighted <br />water sources Sn [he Yoast area. <br />• Adjacent water users Identified Sn Tab 16 will not be impacted by pit pumpage drawdowns ae <br />all are located well beyond the one-Foot drawdown contours for the overburden and Wadge <br />coal units. SCC's Yoast production well will not be in~acted by pit pumpage drawdown <br />because it produces from a hyd raullcally separate aquifer well below the base elevation of <br />[he mine pit. Thus, there is no potential for pit inflow and pit pumpage drawdowns to <br />affect any local water source. <br />Production Well Impacts on Adjacent Water Users. A computer simulation of the effects of <br />the Yoast production well pumpage on streamflow was performed (see Attachment 16-2). The <br />model simulated hydraulic conditions that would compute maximum pumpage and drawdown in <br />the Trout Creek Sandstone for the 15 and 9-year pumping periods for [he Seneca II-W and <br />Yoast production wells. The predicted maximum drawdown of 186 feet was calculated for the <br />Yoas[ well at the end of the 9-year pumping period. The predicted residual draWown of <br />less than 2 feet was tabulated for the end of the 20 year recovery pe rlod to a distance of <br />within 1 mile of [he Yoast production well. Maximum radial distances for the pumping well <br />cone of influence were predicted [o be 10 miles at the one-foot drawdown level, 2.5 miles <br />a[ the 20-foot tlrawdown level, and approximately 1.7 miles at the 50-foot drawdown level. <br />• Dravdown is directed toward the northwest and southeast area of the mine. The non- <br />concentric pattern of drawdown predicted by the model and shown Sn Flqure Ba (Attachment <br />13 Revised 11/01/95 <br />