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BBA's work shows that the closest permitted well (#116113) would be expected to see a <br />drawdown after 20 years of 0.62ft. Much farther away, permitted well (#83553) would be <br />expected to see a drawdown of 0.53 ft after 20 years of pumping. BBA reports that these levels <br />of drawdowns are insignificant and represent less than I% of the available drawdown. None of <br />the permitted wells are located within 600 ft. of PW -001 and no waiver of the 600 ft. statutory <br />limit would be necessary from the State Engineer's office. BBA's report is contained in its <br />entirety in Appendix 2.05.6(3) -la. <br />3) Impact of Spoil Material on Groundwater Flow and Recharge. The mine pit floor will <br />remain open only until the coal has been removed. The pit width will be about 110 ft wide as it is <br />at the adjacent New Horizon Mine. At NHN, each pit advance will take about 2 months so the pit <br />floor is only exposed for a few weeks at a time at most. Water levels in the bed rock zones <br />(overburden, coal, and underburden) will decline in response to the pit face advancement to the <br />north. The bedrock strata will be exposed along 3 sides. The pit side walls will be covered in a <br />relatively short period of time by the advancing backfill and reclamation. Irrigation of the areas <br />to the east, north and west of the permit area will continue unabated throughout the mine life and <br />thereafter and will continue to recharge the bedrock zones in those areas. Monitor hole GW -N8 <br />(see Figure 2.05.6(3)-2a, Appendix 2.05.6(3)-2) experienced a water level decline of about 12.2 <br />ft. in the overburden and coal zone in response to the mining at the old Peabody Nucla Mine. <br />Following backfill and reclamation of the old Peabody highwall (in early 1992), the bedrock <br />zone (OB and Coal) water level at GW -N8 has recovered about 10 ft or 80% of its decline in a <br />period of less than 20 years. This indicates, that following mining the water level in the bedrock <br />zones immediately adjacent to the mined out area that experienced decline will recover. Within <br />the permit area, and south of Meehan Draw (see Map 2.04.7-1), the structural attitude at NHN <br />(see Map 2.04.7-2) is such that irrigation and precipitation water percolating through the <br />reclaimed backfill material will drain to the south along the path of least resistance and issue as <br />spring(s) tributary to Tuttle Draw. To the north of Meehan Draw, any water percolating through <br />the backfill could pond against the "low -wall" and eventually saturate the backfill and issue as <br />springs tributary to Meehan Draw just as the irrigation return water now does. The reclamation <br />plan, (area north of Meehan Draw), is dry land pasture with no irrigation. Figure 2.05.6(3)-1 is a <br />generalized north -south cross-section showing the down gradient drainage through the NHN <br />Mine backfill material. The backfill overburden material at NHN Mine will be placed in the mine <br />pit areas using 3 techniques: 1) cast blasting, 2) end dumping of trucks from the spoil bench and <br />3) dozing. Following top soil stripping, the top bench or free dig zone (weathered zone, suitable <br />material) is loaded into trucks using a hydraulic excavator and hauled around the pit and placed <br />on the top of unsuitable material (unweathered overburden). After removal of the top bench (free <br />dig), the unweathered material is cast blasted (a majority of this material requires re -handling) <br />across the pit to the bottom of the backfill area. Dozers and the shovel and trucks remove the <br />remaining overburden and clean off the top of coal. This backfilling technique greatly increases <br />Section 2.05.6(3) Page 15 April 2016 (PR -01) <br />