2012-01-06_PERMIT FILE - C1982057 (24)

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of storage for additional volumes pumped from pits or sumps. Maintenance of available storage • capacity in the ponds involves dewatering and sediment removal. Ground Water Monitoring. Peabody began ground water monitoring began at Seneca II-W in the summer of 1979. Additional monitoring wells were installed in 1981 and 1987. Currently there are 32 ground water monitoring wells at the Seneca II-W complex. Complete details of ground water monitoring are described in Tab 15, Hydrologic Monitoring Program. Plans to monitor the extent and magnitude of any mining impacts on the ground water system are described in detail in Tab 18, Hydrologic Reclamation Plan. Tab 15 provides an update for the monitoring program including II-W South. Ground water monitoring wells will be maintained for the life of the mining operations or until such time as the DMG may agree that they are no longer necessary. All ground water monitoring installations will be removed upon completion of the postmining hydrologic monitoring phase of the Hydrologic Monitoring Plan unless they are approved for postmining land uses. All ground water data collected from monitoring wells in each water year will be compiled and submitted by the following March i to the DMG in the form of the Seneca II-W Annual Hydrology Report (AHR). • Surface Water Protection Tab 13 (Facilities) contains descriptions, designs, and plans for sediment ponds, roads, diversions, and culverts that have been or will be constructed and utilized at the Seneca II complex. All facilities that are discussed in Tab 13 have been designed to ensure that the hydrologic balance is protected (equal inputs and outputs). Plans for surface water protection are discussed based on the following parts: 1) surface water quality; 2) surface water quantity; and 3) surface water monitoring. Surface Water Quality. Seven sediment ponds (Pond 005, 006, 009, 015, 016, 016A and 017) are currently in operation at the Seneca II-W Mine. The sediment ponds will be used for controlling surface water runoff from disturbed and reclaimed areas. Ponds 009, 015, 016, 016A and 017 are proposed to be temporary structures, while Ponds 005 and 006 will serve as permanent impoundments to remain after mining. Each pond is designed to prevent additional sediment input to the streamflow outside the permit area, to minimize erosion, and maintain sufficient detention time to ensure that all applicable effluent standards will be met. Pond discharge structures are designed according to standard engineering design procedures for protection against erosion by installation of riprap and/or energy dissipators. Any plans for modification of a sediment pond will be submitted to the DMG for approval prior to construction. The temporary ponds for Seneca II-W and Seneca II-W South mines will be • removed and reclaimed after the completion of mining and reclamation. TR-50 3 Revised 11104