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The slurry backfill operation has an estimated life of 5 years. Mine workings will be <br /> monitored for water quality and recovery of the formation aquifer. Monitoring informa- <br /> tion, backfill volumes, and water quality will be reported in the annual hydrology report. <br /> The slurry backfill operation has been designed to minimize adverse impacts to the <br /> hydrologic balance. <br /> There will be a number of benefits resulting from disposal of coal fines underground. <br /> First, underground disposal of coal fines will increase the stability of the coal refuse pile. <br /> Currently the coal fines are disposed in the refuse pile. The fines often create disposal <br /> problems because when they are recovered from the preparation plant, they are <br /> saturated and do not dry well due to their fine-grained nature. In this state, the fines do <br /> not compact and create a stability problem in the refuse pile if not handled properly. <br /> Second, underground disposal of coal fines will extend the life of the coal refuse pile, <br /> reducing the immediacy for construction of a new disposal area. Third, underground <br /> disposal of the fines may diminish the magnitude of subsidence, if any were to occur, in <br /> the mains. The filling of the void spaces in the mains with coal fines will give some <br /> support to the roof if subsidence should occur. <br /> Due to the continuing use of most of the surface facilities, much of the disturbed area will <br /> not be cleared of structures and reclaimed until the completion of mining. When actual <br /> coal extraction ceased, the portals were temporarily sealed. Backfilling and final sealing <br /> has not occurred at this time (February 1999). The bench areas will be graded to the <br /> approximate original contour. The disturbed areas will be topsoiled to the extent topsoil <br /> is available, then seeded and mulched to establish a vegetative cover of a variety <br /> consistent with surrounding vegetation. The stream channel diversion of the Middle <br /> Fork of the Purgatoire River, which was approved under Permit Revision #1, is <br /> permanent and will remain as constructed. Monitoring has demonstrated that this work <br /> was successful and the reconstructed channel is stable. <br /> Topsoil will be salvaged from the area above the RDA during each successive <br /> movement of the clean water diversion ditch above the RDA. This material will be used <br /> in the reclamation of the pile. Any other suitable soil material available will be used to <br /> reclaim the areas of the existing and proposed surface facilities. Due to previous <br /> disturbance prior to the enactment of the Colorado Surface Coal Mining Reclamation <br /> Act, very little topsoil is available for use during reclamation of areas previously <br /> disturbed. <br /> The post-mining land use is rangeland, which is compatible with the surrounding uses. <br /> The proximity to the Purgatoire River and heavily forested areas to the south indicate a <br /> high probability of wildlife use following reclamation. Riparian vegetation as well as <br /> native grasses and shrubs are planned. <br /> -8- <br />