2014-05-12_PERMIT FILE - C2010089 (3)

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SECTION 2.04.7 HYDROLOGY DESCRIPTION The New Horizon North (NHN) permit area is shown on Map 2.04.7 -1, Hydrology Monitoring Site Locations, contained in the appendix of this section of the application. The NHN permit area is adjacent to WFC's active New Horizon Mine and incorporates part of the old Peabody Nucla Mine. Peabody performed detailed hydrologic studies at the New Horizon 1 & 2 mine areas (formerly called the Nucla and Nucla East mine areas, respectively). WFC continues to conduct water level and water quality monitoring at the New Horizon Mine. WFC refers the reader to the original Peabody permit application: Volumes B, C, D, E, F, and G for hydrology data related to old Nucla Mine (New Horizon 1 Mine area). During the spring of 2008, WFC met with DRMS personnel to discuss and agree upon a hydrologic monitoring program for the NHN permit area. The resulting plan resulted in the drilling of 9 hydrologic monitoring wells (GW -N47 through GW -N55) during the fall of 2008 and the establishment of 15 new surface water monitoring stations (SW -N200 through SW -N214) and two current New Horizon Mine stations (SW -N1 and SW -N3) to supplement the existing data that had been collected in the area at the New Horizon Mine 2 area and in the New Horizon Mine 1 area. Five additional surface water monitoring sites (SW210 — SW214) were later added. Of the nine ground water monitoring wells, three (GW- N49, GW -N52, and GW -N55) were drilled and completed as overburden monitoring wells, three were completed as coal zone monitoring wells (GW -N48, GW -N51, and GW -N54) and three were completed as underburden monitoring wells (GW -N47, GW -N50, and GW -N53. Map 2.04.7 -1 shows the locations of the nine new ground water monitoring wells. Map 2.04.7 -1 also shows the location of six ground water monitoring wells that were completed by Peabody in (and adjacent to) the incorporated area of New Horizon 1 Mine area. Map 2.04.7 -1 also shows the locations of the 17 new surface water monitoring sites (SW -N1, SW -N -3 and SW200 - SW214) as well as monitoring sites established by Peabody for the New Horizon 1 Mine area. After permit approval and prior to new disturbance, three (3) new ground water monitoring wells were installed in the southwestern portion of the NHN permit area. The locations of these 3 new wells are shown on Map 2.04.7 -1. New ground water monitor well GW -N56 will monitor the underburden (UB), well GW -N57 will monitor the coal zone (Coal) and well GW -N58 will monitor the overburden. GW -N56 was completed on August 8, 2012 while GW's N57 and N58 were completed on August 9, 2012. The completion diagrams for the three new monitor wells are shown on Figure 3 of Appendix 2.04.7 -1. These wells will be monitored and reported on the same cycle as the other ground water monitoring wells. It is anticipated that these wells will become the points of compliance after review of additional data and consultation with DRMS. SITE SPECIFIC GROUND WATER INFORMATION AND BASELINE DATA Introduction Regional and site specific geology and physiography pertinent to the description of ground water resources in the NHN Mine permit area are discussed in Section 2.04.5 and 2.04.6. Maps 2.04.5 -1 (General Geology and Hydrology Map), 2.04.6 -4 and 2.04.6 -5 (Geologic Cross Sections A —A' and B -B') graphically illustrate the site specific geology at the NHN area. New ground water monitoring wells GW -N47 through GW -N49 are located on the northwest end of Cross Section A -A'. Monitoring wells GW -N50 through GW -N52 and GW -N53 through GW -N55 are located on the northeast and southwest ends respectively of Cross Section B -B'. Section 2.04.7 Page 1 October 2013 (TR -05) N: \WFC \2013 \NHN \DRMS Permit Revisions \TR -05 \2.04.7 Hydrology Description_TR- OS.docx