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December 1.7.443 <br />Pag¢ 3-5 <br />lowering of the surtace after the longwall shear removes the coal. Some cracking might be evident as the <br />shear passes, and along the fringes of the extracted panel. Due to the overburden thickness in the lease <br />tract, it is anticipated that subsidence would not be easily identified by casual observers. There is <br />potential that mining subsidence could aggravate existing landslides or other geologic hazards in the <br />area. See Figure 3-1, Geologic Hazards Map. <br />The duration of subsidence resulting from mining would occur rapidly, beginning almost immediately after <br />mining. The duration of residual subsidence movements above longwall panels is relatively short, typically <br />varying from a few weeks up to a few months. Mining induced seismic events as a result of longwall <br />mining would be minimal. These events should not inflict any damage to surface resources. <br />The BLM projects the presence of four areas of faulting in the LBA tract. The areas of faulting are <br />expected to be evenly spaced north to south, and are projected from occurrences in existing mine <br />workings. These faults are occurring as fracture zones, as showing slight offset, or offset as much as 21 <br />feet. These faults are generally not discernible on the land surface, and are not expected to induce <br />surtace impacts. Encountering faults underground may slow operations, or induce conditions where <br />additional roof support for the mine would be needed. <br />Alternative 2 - No Action <br />If the no action alternative is selected, coal would not be mined in the LBA tract. The coal resource would <br />remain in place. The potential to recover the coal resource at some time in the future would be <br />questionable given the planned mining at the West Elk Mine. MCC would not extend its planned longwall <br />panels into the LBA tract. The coal would thereby be "bypassed" and left isolated with little or no chance <br />that the coal would ever be mined in the future. Landslides and rock falls would continue to occur under <br />natural conditions. <br />3.3.3 Potential Lease Stipulations <br />Subsidence monitoring and mitigation programs are discussed in Section 3.2.3, Management and <br />Mitigation Measures. These programs are required by the Colorado DMG as part of their permitting <br />program or as lease stipulations imposed on the operator/lessee by the BLM and would be highly <br />effective in reducing or eliminating impacts to the topography and geology on the LBA tract. <br />t) No surtace occupancy would be allowed in areas of high geologic hazard. Implementation of this <br />mitigation measure would be highly effective in preventing surface related impacts to the <br />topography and geology of the LBA tract. <br />3.4 Water Resources <br />For water resources, the project impact area is the W est Flatiron LBA tract area and the lower portion of <br />the Raven Creek watershed. The cumulative impact area is the area encompassed by the West Elk Mine. <br />Environmental Fsssssment <br />iNest Flatiron LB.A Tracy <br />G~.~nnison !7ount;~, Colorado <br />