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The fmal area to be impacted by subsidence is associated with mining of the 16 -Right Panel. The State of <br /> Colorado is the surface owner of the parcel to be undermined and subsided. As presented above, a total of 4 <br /> acres will be flooded by the mining of this panel. As is the case for all lands along Fish Creek to be undermined <br /> and subsided, no flood irrigation system has been established to increase the productivity of the land nor are <br /> management practices established for haying this area. The land is treated as unimproved rangeland, utilized for <br /> grazing by TCC's grazing lessee. <br /> Ashley Impoundment and Irrigation Ditch - The Ashley impoundment is located in the SW /4SW /4 of Section <br /> 15, T5N, R86W. This impoundment is of earthen construction, and typically holds water throughout the year. <br /> The headgate for the irrigation ditch is located in the SE /4NE /4 of Section 19, T5N, R86W. TCC has <br /> undermined and subsided sediment ponds during the mining of reserves located in the west part of the Permit <br /> Area. No material damage to the ponds resulted from mining activities. It is anticipated that the Ashley <br /> impoundment will react in the same manner. If cracks develop in the embankment, they will be repaired and <br /> regraded, to maintain the integrity of the impoundment. <br /> In reference to the smaller impoundment, TCC does not plan any maintenance for this structure due to its <br /> current poor condition. If the owner repairs and upgrades it prior to mining, TCC will perform any necessary <br /> repairs, as needed. <br /> NMD and WMD (Panels 17- through 24 -Right and 12- through 17 -Left, PR 03 -06, PR06 -07 and PR09 -08) <br /> Proposed mining in the remaining portion of the NMD, and longwall mining of the WMD reserves should not <br /> result in material damage or diminution of reasonably foreseeable use of structures or resources. Structures <br /> which will be undermined and subsided include portions of County Roads 27 and 37A, ranch roads, powerlines <br /> (Public Service, Western Area Power Association, Tri- State, and Yampa Valley Electric Assn.), portions of the <br /> Union Pacific Railroad Spur (formerly Denver & Rio Grande), Fish Creek and its associated Alluvial Valley <br /> Floor areas, several stock ponds, TCC monitoring wells and surface water monitoring sites, and portions of the <br /> Twentymile Sandstone, as a natural feature. It should be noted that mining- related subsidence is not expected to <br /> impact the proposed 6MN Reservoir, since the Reservoir is entirely outside of the projected subsidence limits, <br /> and the Reservoir embankment is a minimum of 540 feet from the nearest supported mine workings <br /> (development entries) and 1,250 feet to the nearest projected subsidence limit line (refer to 6MN Storage <br /> Reservoir — distance from Embankment Structure to Current and Future Supported and Subsided Mine <br /> Workings, Exhibit 490). <br /> Aquifers - The Twentymile Sandstone is the only regional aquifer above the coal seam. It is not anticipated that <br /> any water supply wells will be impacted from undermining of the Twentymile Sandstone, since no supply wells <br /> in the Twentymile Sandstone exist in the affected area. TCC's ongoing hydrologic monitoring program does <br /> not show any impacts to this formation outside of the mining area. <br /> County Roads 27 and 37A and Ranch Roads - Relative to the response of existing roads to undermining and <br /> subsidence, TCC has gained considerable applicable local experience through previous undermining of RCR27 <br /> and RCR33 in the SWMD and EMD. Experience confirms that subsidence does not significantly change road <br /> configuration or disrupt use of the road, since any resulting changes in road elevation and gradient are gradual <br /> and incremental. While asphalt pavements are somewhat flexible, any significant changes in elevation/gradient <br /> may result in tensile or compressive forces that may cause localized cracking or buckling of the road surface. In <br /> either case, gravel can be placed as a temporary repair, then hot tar or asphalt can be used to fill any cracks or <br /> voids. For larger areas of cracking or buckling, or where heavy loads or traffic is anticipated, a permanent <br /> asphalt overlay may be appropriate. Ranch roads are either dirt- or gravel - surfaced. Any damage to these roads <br /> can be readily repaired by regrading the road. Any necessary temporary and permanent repairs, assure that <br /> material damage or diminution of reasonably foreseeable use of roads does not occur. <br /> For a segment of RCR33 overlying the 9 -Right Longwall Panel that was damaged by subsidence, temporary <br /> placement of gravel allowed continued use of the road, and an asphalt patch returned the road to a condition <br /> comparable to its premining condition. Where RCR33 crossed the 8 -Right Panel, subsidence caused the road to <br /> buckle. The damaged area was excavated, gravel was placed as a temporary repair, and following completion of <br /> PR09 -08 2.05 -184.7 04/29/09 <br />