2012-06-20_PERMIT FILE - C2010089A (28)

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Water accumulating in the pit(s) will be removed by pumping the water to a sediment pond that will, at the time of pumping, have a sufficient available storage capacity, including the prescribed volume for the 10 -year, 24 -hour storm. Design criteria for all ponds are addressed in Section 2.05.3(3), Mine Facilities, and include plans for storage of additional volumes pumped from pits or sumps. Maintenance of available storage capacity in the ponds involves dewatering and sediment removal. Ground Water Monitoring Since 1979, Peabody (New Horizon Mine's predecessor) and WFC have installed an extensive network of 46 hydrologic monitoring holes to monitor the shallow bed rock zones beneath both the New Horizon 1 and the New Horizon 2 mining areas. A number of these holes were located within or in close proximity to the NHN permit area (see Map 2.04.7 -1 in Section 2.04.7, Hydrology Description). This information has been supplemented by the addition of nine new hydrologic monitoring holes which were installed during 2008 for baseline hydrologic data collection. These new holes (numbered GW -N47 through GW -N55) are described in Section 2.04.7 and the data collected presented in Appendices 2.04.7 -1. Physical data (temperature, pH, conductivity, depth) are collected monthly and samples for chemical analyses are collected quarterly. This schedule will continue for the foreseeable future. It is expected that these nine new baseline monitoring holes will be employed to monitor the extent and magnitude of any mining impacts as also discussed in Sections 2.04.7 and Section 2.05.6(3)(b)(v), Hydrologic Reclamation Plan. The ground water monitoring holes will be maintained for the life of the mining operations or until such time as DRMS may agree that they are no longer necessary. All ground water monitoring installations will be removed upon completion of the post mining hydrologic monitoring phase of the Hydrologic Monitoring Program. All ground water data collected from monitoring wells in each future water year will be compiled and submitted to DRMS in the form of the New Horizon Annual Hydrology Report (AHR). The AHRs will be submitted within three months after the end of each water year. Surface Water Protection Section 2.05.3(3), Mine Facilities, contains descriptions, designs, and plans for a sediment ponds, roads, diversions, and culverts that will be constructed and utilized at New Horizon North mining area during mining All facilities that are discussed in Section 2.05.3(3) have been designed to ensure that the hydrologic balance is protected. The discussion for surface water protection has been separated into three parts: 1) surface water quality; 2) surface water quantity; and 3) surface water monitoring. Surface Water Quality Sediment ponds will be adequately designed and will be constructed during the proposed operations for controlling surface water runoff from disturbed and reclaimed areas. An NPDES permit will be obtained from Water Quality Control Division, Colorado Department of Public Health and Environment to allow the discharge of water from the sediment Section 2.05.6(3) Page 4 November 2011