Laserfiche WebLink
0 2.05.6(6) <br />Also when, during development of the panels near the outcrop, low quality <br />coal is encountered, one row of development pillars will be left in place to <br />prevent the potential crushing, sliding, or other failure near the outcrop. See <br />Exhibit 15, Section 1.7. Zones Along Outcrop Barrier Pillar. <br />The applicant plans to mitigate the risk of damage to the Pitkin Mesa pipeline <br />by installing a 6 -inch diameter heat fusible high density polyethylene pipe <br />(HDPE) on the surface above the existing buried PVC pipe through the <br />projected zone of subsidence. The new HDPE pipe will be joined to the <br />existing PVC pipe outside the projected zone of subsidence. Two years after <br />mining the HDPE pipe will be buried adjacent to the existing PVC pipe. <br />The fundamental of heat fusion welding is to heat two HDPE pipe surfaces to <br />an appropriate temperature and then fuse them together by application of <br />prescribed force until cooling occurs, returning the material to its original <br />state and creating one homogeneous pipe. <br />M As explained in Exhibit 15, Section 1.6, data from the Bowie No. 1 Mine and <br />field measurements of subsidence cracks in the Mesaverde Formation by <br />Dunrud (1976), indicate subsidence cracks may develop through overburden <br />thicknesses of up to 800 feet under unfavorable conditions. While <br />unfavorable conditions can not be defined exactly, they may include zones of <br />weathered coal and overburden. Under normal conditions, subsidence <br />cracks do not appear likely to propagate through more than 500 feet of <br />overburden. <br />PR -12 2.05-146- 07/10 <br />A PPRoV E D <br />II/Ir./lo <br />