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Mining conducted in the Eastern Mining District (EMD) and longwall panel 12 in the <br />Northern Mining District (NMD) undermined portions of Routt County Road No. 33. <br />TC conducted daily monitoring of the road when the longwall panels were <br />approaching and undermining the road. When surface observations found the asphalt <br />road surface had buckled or been damaged due to subsidence, TC temporarily repaired <br />the surface using gravel. Once subsidence monitoring indicated that subsidence had <br />ceased, permanent asphalt overlay or patch was applied to the damaged road section. <br />This method was successfully used during the mining of Longwall panels 9R, 8R, 7R, <br />6R and 5R in the Eastern Mining District, and Longwall panel 12R in the Northern <br />Mining District. Twentymile Coal re -paved segments of Routt County Road No. 33 in <br />the fall of 1999 that had experienced damage due to subsidence of Longwall Panels 5R <br />and 6R. Twentymile Coal scaled loose rock from the slope above Routt County Road <br />No. 33 prior to undermining Longwall panel 12R, and placed temporary concrete <br />barriers or chain link meshing along the north side of Routt County Road No. 33, to <br />ensure that rockfall would not reach the road. <br />PR -10 proposes to undermine Routt County Road 33. The road is located over the <br />southern gateroad for the 5RT longwall panel. TC will monitor the road for <br />subsidence impacts. Warning signs will be installed for road damage and rockfall; <br />also, signs will warn drivers they are entering a subsidence zone. TC will repair or <br />fund the repair of damage to the road caused by subsidence. <br />Union Pacific Railroad <br />Previously, when monitoring indicated that the track was damaged or the grade had <br />changed, a slow speed restriction was instituted. Re -leveling and repair of the track <br />occurred in accordance with mitigation plans required by Union Pacific Railroad. <br />During the mining proposed with PR -10, TC will monitor the railroad track for <br />subsidence impacts. TC will pre -ballast and/or re -level portions of the railroad track <br />to assure no service to the mine is disrupted. TC has indicated that these methods <br />were successfully implemented in the past during mining in the Eastern and Northern <br />Mining Districts. <br />Hayden -Gore Pass Powerline <br />TC notified the utility company 30 days prior to undermining the powerline in addition <br />to the Division's requirement to provide six months notification prior to undermining. <br />TC monitored the powerline structures daily. The powerline was subsided without <br />interruption or significant damage to the powerline towers. Power company personnel <br />inspected the powerline after subsidence had occurred and found that deformation of <br />the structures was within company specifications and did not require Twentymile Coal <br />to conduct repairs. Information regarding subsidence of the Hayden -Gore Pass <br />powerline can be found in the 1997 and 1998 Subsidence Reports. <br />Archer -Hayden, Western Area Power Administration, Tri-State, and Public Service <br />Pnwerlines <br />Page 37 of 52 <br />