2016-01-07_PERMIT FILE - C2010089A (3)

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winter to summer. The under burden zone artesian head at GW -N50 varies from about 15 feet to about 39 feet above the zone from winter to summer. Backfill Water Levels The NHN permit area encompasses part of the area of the old Peabody Nucla Mine, which ceased production in 1983. Overburden backfill material exists south of the old Peabody high -wall. Four wells (GW -N10, GW -N26, GW -N27 and GW -N28) monitored water levels in this backfill material through the end of 1987. All four of these wells were abandoned and reclaimed in November of 2001. Map 2.04.7-1 shows the backfill monitor well locations. The backfill is essentially dry with the exception of the area in the vicinity of GW -N27 and GW -N10. At GW -N27 the back fill has approximately 6.4 feet of maximum saturation. At GW -N10 the backfill is dry from time to time with maximum saturation of only slightly more than 1 foot. GW - N27 was installed in August of 1987 and shows seasonal fluctuation of a little over 3.0 feet corresponding with run off from the irrigation flow ( hydrographs for monitor wells GW -10 and GW -27 are contained in the Appendix 2.04.7-1 of this section). Recharge and Hydrologic Boundaries The predominate source of recharge to the shallow bedrock zones at the NHN permit area is direct leakage from the 2nd Park Lateral irrigation ditch where it crosses the outcrop of each of the respective zones (overburden, coal and underburden) and infiltration of excess flood irrigation waters into the weathered overburden. Minor recharge also results from infiltration of precipitation. Discharge is down dip to the outcrops and old Peabody high -wall (see Map 2.04.5-1 of this application). Although exploration drilling has indicated the presence of faults (see Map 2.04.6-2), there is no evidence that the faulting is affecting ground water flow. Infiltration and Permeability of the Unsaturated Zone Using the soil hydrologic properties defined by the Soil Conservation Service of the U.S. Department of Agriculture, it is possible to estimate the infiltration rates of soils occurring within the vicinity of the New Horizon 1 & 2 mining areas. The New Horizon 1 & 2 soils have been mapped at a scale of 1 inch equals 400 feet. The soils maps are included in Section 2.04.9 of this permit application. At the adjacent New Horizon 2 Mine the majority of the soils have a moderate (0.6 - 2.0 in/hr) permeability and infiltration rate. A minor amount of the soils have a moderately rapid (2.0 - 6.0 in/hr) permeability and infiltration rate. The subsurface strata in these areas consist predominately of tightly cemented sandstones and shales which act as barriers inhibiting vertical percolation. However, field observation of exposed outcrops, mine high -walls, and aquifer analysis data indicate that secondary porosity (weathered and fractured bedrock strata) play a significant role in allowing vertically infiltrating ground water to infiltrate through the unsaturated to the saturated zone. The NHN permit area is impacted by irrigation which is a primary source of infiltrating water. Infiltration as a result of precipitation is only a minor component of recharge in the NHN area but the majority of infiltration comes from irrigation. The large majority of the soils in the mining area have a slow to medium runoff potential. The strata at the NHN permit area and the New Horizon Section 2.04.7 Page 5 Sept. 2015 (TR -11)