Laserfiche WebLink
Union Pacific Railroad (formerly Southern Pacific) <br />Due to the change in the mine plan, no further subsidence will be experienced by the mining of the 6 Right <br />longwall panel. <br />Powerlines - <br />Twentymile successfully undermined and subsided the powerlines during the mining of panel 9 Right. The <br />powerlines were monitored per the approved plan; this data was presented in the semi - annual subsidence report. <br />The results of the monitoring show that the lines subsided, but the did not fail or experience foundation failure. <br />This verified the contention that no impacts will be realized due to undermining and subsiding the lines. <br />The subsidence prediction for powerlines is presented in Exhibit 7E, Prediction of Subsidence, Eastern Expansion <br />of Foidel Creek Mine, prepared by Sub Terra, Inc. in March 1993. As is shown, the subsidence will vary from 0 to <br />73 inches over the various panels. For panels 4 Right through 6 Right, maximum subsidence is 67 inches, while <br />maximum subsidence for panels 2 Right and 3 Right is 73 inches. <br />The powerlines will be monitored, as described in the subsidence control plan, on the basis of distance from the <br />active longwall mining face to the powerlines. The monitoring will allow for rerouting power in the event the <br />Hayden -Gore Pass (metal structure) is impacted temporarily. Once the line is stabilized, power would be returned <br />to the line. A copy of the subsidence agreement, which includes rerouting power and ground -fault interruption <br />processes, has been forwarded to the Division. <br />The wooden structures supporting the other three powerlines should react the same as the wooden structures <br />undermined and subsided in the Southwest Mining District. The line experienced up to 3.1 feet of subsidence <br />without failure to the line or the pole(s). This line has been visited by the DMG inspector during prior inspections <br />conducted at the mine. The subsidence data for this line is presented in Exhibit 7G, Subsidence Report for YVEA <br />Power Poles. <br />The gang switch for the Wolcott Tap - Wolcott 230 KV transmission line was relocated during 1996 to an area <br />outside the mine area. No problems were encountered when the line was subsided by the 9 Right panel. It is <br />anticipated the line will continue to respond to future subsidence. <br />As of November 1999, TCC has undermined the powerline located over the 6 and 5 Right panels. The results of <br />the monitoring has been included in the semi -annual subsidence reports, and the results have not changed, i.e. no <br />significant impacts to the line or support towers /poles. <br />Telephone Lines <br />The buried telephone lines are not expected to be impacted by the mining operation. Twentymile has undermined <br />and subsided a section of buried line in the Southwest Mining district. In the event there is a disruption in service <br />(i.e. line severed), Twentymile would become aware of it immediately as the mine is served by that line. If service <br />were disrupted, a repair crew would be called out to service the line. <br />The line was subsided by mining conducted in the 6 and 5 Right panels without disruption to service. <br />Aquifers <br />The Twentymile Sandstone is the only large regional aquifer that is above the coal seam. It is not anticipated that <br />any wells will be impacted from the undermining of the Twentymile Sandstone. The present hydrologic monitoring <br />program conducted by Twentymile Coal Company does not show any impact to this formation outside of the <br />mining area. Therefore, it would be prudent to predict no off -site impacts to this unit. <br />APPROVED APR 2 4 2000 <br />Permit Renewal No. 3 1 2.05 -184.1 11/1/99 <br />