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SubTerra, Inc. Twentymile Coal Company 6/19/2003 <br />PR6 Rail Line Evaluation <br />• anticipate that any residual issues can be completely resolved during detailed planning for 17- <br />Right's undermining of the Energy Spur track. <br />4.2 Track Coordinate and Elevation Data <br />A continuous rail has been installed since the original survey for the Energy Spur track was <br />performed. The track will therefore need to be re-surveyed prior to conducting the detailed <br />remedial planning tasks outlined in 3.3 above. <br />5. Conclusions <br />Some general conclusions that can be drawn from the preliminary work include: <br />1. The majority of the movement associated with each longwall will occur over cone-month <br />period starting when the face is within about 300-ft of the rail line and will be substantially <br />complete when the face is about 500-ft past the rail line. This distance is measured <br />parallel to face retreat. <br />2. During pre-ballasting, track differential gradients will generally be maintained below 0.4% <br />between adjacent Stations. Final differential gradients are predicted to be at or below <br />0.3% following subsidence from each of the planned longwall panels. <br />3. Re-ballasting may require placement of fill or ballast in Fish Creek or its AVF at Stations <br />• 401 and 387+50 where the energy Spur crosses the creek. However, detailed survey data <br />are required before a final determination can be made. <br />4. Both of the two remedial methods outlined in this report have been successfully <br />implemented during undermining of the Energy Spur. There is every reason to conclude <br />that they will continue to be successfully applied to remediating subsidence associated <br />with extraction of the remaining panels. <br />• <br />