2009-10-30_PERMIT FILE - C1982056A (5)

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RESPONSE • TCC does not expect any material damage or diminution of value or foreseeable use of the land from subsidence as a result of the pillar extraction upon retreat mining in the various panels. No subsidence is expected under the / segment of Foidel Creek located in the Western Mining District. Consequently, no measures will be taken on the surface with respect to subsidence control other than the planned monitoring operations. Extension of Panels 5 and 6 under the designated Fish Creek AVF resulted in limited subsidence. Related subsidence effects did not, significantly impact the AVF or associated hydrologic or vegetation resources. In conjunction with planned undermining, TCC has completed detailed subsidence projections, evaluated potential related effects, and has developed, and implemented, appropriate subsidence, hydrologic, and vegetation monitoring. These measures, as detailed in Exhibits 7B, 45, and 46, Fish Creek AVF/Stream Study--Subsidence Projects, Hydrologic Analysis, and Vegetation Analysis, respectively, were designed to insure that material damage or diminution of reasonably foreseeable use did occur. EASTERN MINING DISTRICT (Panels 9 Right through 7 Right) Subsidence Control Plan The mining in the Eastern Mining District did not result in any material damage or diminution of reasonably foreseeable use of structures or resources in the five-year mine plan (1993 - 1998). The structures within the five- year mine plan area include County Road 33, Union Pacific Railroad, powerlines (Public Service, Tri-State, Western Area Power Association, Platte River Power Authority, and Yampa Valley Electric Association), telephone lines (U.S. West), Twentymile Sandstone, and Foidel and Middle Creeks. • County Road 33 In reference to County Road 33, Twentymile gained experience from undermining and subsiding County Road 27. The experience indicated that either tensional or compressional fractures were manifested in the road surface. This resulted in either cracking or buckling of the road surface. In either case, gravel was brought in to provide a temporary repair to the roads' surfaces. The permanent repair program, asphalt patches or overlay, insures that material damage or diminution of reasonably foreseeable use of the road did not occur. Union Pacific Railroad (Formerly Southern Pacific Railroad) In reference to the Union Pacific RaiUoad (Formerly Southem Pacific Railroad and Denver Rio Grande), this rail line was subsided, but no material damage or diminution of reasonably foreseeable resulted. The subsidence projections indicate there will be grade change within the course of the track. However, Twentymile or representatives of the railroad inspected the track on a daily basis during the subsidence period. In the event there were grade changes, which disrupted traffic, the railroad tracks were repaired. The repair focused on re-leveling the track and having a slow speed restriction on during that time period. The monitoring and repair of the track occurred during mining of panels 7 Right through 9 Right in the Eastern Mining District. During the repair of the track, additional ballast was required to re-level the track. [t was be replaced on an as needed basis. Twentymile stockpiled additional ballast for the repair work. APPROVED APR 2 4 2000 Permit Renewal No. 3 2.0~-195 I I/1/99