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of storage for additional volumes pumped from pits or sumps. Maintenance of available storage <br />capacity in the ponds involves dewatering and sediment removal. <br />• <br />Ground Water Monitoring. Peabody began ground water monitoring began at Seneca II-W in the <br />summer of 1979. Additional monitoring welts were installed in 1981 and 1987. Currently there are 32 <br />ground water monitoring wells at the Seneca II-W complex. Complete details of ground water <br />monitoring are described in Tab 15, Hydrologic Monitoring Program. Plans to monitor the extent and <br />magnitude of any mining impacts on the ground water system are described in detail in Tab 18, <br />Hydrologic Reclamation Plan. Tab 15 provides an update for the monitoring program including II-W <br />South. <br />Ground water monitoring wells will be maintained for the life of the mining operations or until such time <br />as the DMG may agree that they are no longer necessary. All ground water monitoring installations will <br />be removed upon completion of the postmining hydrologic monitoring phase of the Hydrologic <br />Monitoring Plan unless they are approved for postmining land uses. <br />All ground water data collected from monitoring wells in each water year will be compiled and <br />submitted by tha following March 1 to the DMG in the form of the Seneca II-W Annual Hydrology <br />Report (AHRI. - <br />Surface Water Protection <br />• <br />Tab 13 (Facilities) contains descriptions, designs, and plans for sediment ponds, roads, diversions, and <br />culverts that have been or will be constructed and utilized at the Seneca II complex. All facilities that <br />are discussed in Tab 13 have been designed to ensure that the hydrologic balance is protected (equal <br />inputs and outputsl. Plans for surface water protection are discussed based on the following parts: 1) <br />surface water quality; 21 surface water quantity; and 31 surface water monitoring. <br />Surface Water Quality. Three sediment ponds (Pond 005, 006, and 0091 are currently in operation at <br />the Seneca II-W Mine and Ponds 015, 016, and 017 for II-W South are planned. The sediment ponds <br />will be used for controlling surface water runoff from disturbed and reclaimed areas. Ponds 009, 015, <br />016, and 017 are proposed to be temporary structures, while Ponds 005 and 006 will serve as <br />permanent impoundments to remain after mining. Each pond is designed to prevent additional sediment <br />input to the streamflow outside the permit area, to minimize erosion, and maintain sufficient detention <br />time to ensure that all applicable effluent standards will be met. Pond discharge structures are <br />designed according to standard engineering design procedures for protection against erosion by <br />installation of riprap and/or energy dissipators. Any plans for modification of a sediment pond will be <br />submitted to the DMG for approval prior to construction. The temporary ponds for Seneca II-W and <br />Seneca II-W South mines will be removed and reclaimed after the completion of mining and <br />reclamation. <br /> <br />3 ~ Revision 9198 <br />