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Mine are the same. The lithologic logs indicate that the back fill material will generally be <br />composed of more than 50 percent fragments of blasted sandstone with lesser amounts of shale <br />and siltstone and minor amounts of bentonite. Sections 2.05.3 and 2.05.4 describe the details of <br />the mining and reclamation methods. The recharge capacity and permeability of the back fill <br />material will be increased due to greater porosity and hydrologic conductivities than the <br />undisturbed strata due to increased void volumes. As an example, Peabody conducted a constant <br />discharge pumping test in the backfill (spoils) of the old Peabody Nucla Mine using the formula <br />for the well recovery at GW -N27. The results of the test showed the backfill material to have a <br />transmissivity of 261 ft2/day and a hydraulic conductivity of 40 ft/day (about 0.21 gpm/ft2) which <br />are many times higher than average values of transmissivity and hydraulic conductivity from tests <br />of the overburden, coal and underburden zones in the area (see Tables 7-5 and 7-6, pgs. 7-22 and <br />7-24 of the New Horizon 1 Mine Permit copies of which are contained in the Appendix 2.04.7-2 <br />to this Section). The resaturation of the back fill material will be greatly limited by its tendency to <br />drain down dip along the floor of the pit to the existing outcrop where it will discharge at Spoil <br />Spring # 1 (SS#1) as it currently does (see Map 2.04.7-1 for the location of SS#1 and SS#2). <br />Discharge Discharge rates from the coal and the underburden is relatively small compared to the <br />overburden which is more a function of the thickness of the respective zones than it is the <br />difference in lateral permeability. Again, seasonal irrigation is the cause of the saturation of the <br />NHN strata as the monitoring wells show. Without the seasonal irrigation the NHN strata would <br />be dry. The overburden strata is the primary source of discharge to the drainages of Tuttle Draw <br />(to the south) and Coal Canyon (to the west) which help maintain the surface water base flow of <br />the two drainages (see Map 2.04.5-1 this application showing coal outcrop). The primary factor of <br />which is the much greater surface area of recharge from the seasonal irrigation for the overburden <br />than for the other two zones. Fourteen aquifer tests have been conducted on the overburden, coal <br />and underburden strata in the NHN permit area (see Tables 7-5 and 7-6, ppgs.7-22 and 7-24 of the <br />New Horizon 1 Mine Permit copies of which are contained in the Appendix 2.04.7-1 of this <br />Section). These tests show average hydraulic conductivities for: the overburden of 0.72 ft/day; the <br />coal zone of 0.19 ft/day; and the underburden of 1.61 ft/day. One of these tests was at GW -N9 <br />which is located within the NHN Permit area (see Map 2.04.7-1). This was a slug test analysed by <br />the McWhorter method on the overburden and coal zone. The results of this test indicated a <br />hydraulic conductivity of 2.1 ft/day for the two zones combined, (see Table 7-5, pg 7-22 of the <br />New Horizon 1 Mine Permit a copy of which is contained in the Appendix 2.04.7-1 to this Section). <br />Estimating discharge from the overburden, coal, and underburden zones into the NHN pit can be <br />based on the average overburden zone aquifer characteristics. For the overburden, the average <br />hydraulic conductivity (or K) is 0.72ft/day. The pit length will be about 2,197 feet long. The <br />average saturated thickness of the overburden zone just north of the highwall is about 16 feet. The <br />average gradient in the overburden just north of the highwall is about 0.05. Based on the existing <br />overburden characteristics, the annual discharge from the highwall is calculated using Darcy's <br />Section 2.04.7 Page 6 Sept. 2015 (TR -11) <br />