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2.05.6(6) <br />The subsidence implications of mining through the fault are summarized in <br />Exhibit 15. Inadequate roof support could result in a conical chimney <br />collapse which could breach 285 feet of overburden. Additionally, regardless <br />of the depth, when a fault is encountered and coal is mined beneath the fault <br />plane on the upthrow side of the fault, a step on the surface could result. As <br />explained in section 2.05.3(1), the Operator is committed to adequately <br />support the openings developed through the fault trace to avoid the <br />subsidence implications explained above. <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 schedule 80 6 -inch diameter heat fusible high density <br />polyethylene pipe (HDPE) adjacent to the existing Pitkin Mesa pipeline. The <br />new pipe will be placed in a trench excavated next to the existing pipeline. <br />The new pipe will replace the existing pipeline. The existing pipeline will be <br />capped and remain in place. <br />The new pipeline will be joined with the existing pipeline on each end of the <br />pipe replacement project. The tie in will take about one day. The Pitkin <br />Mesa Water Pipeline flows into a 500,000 tank. The water users obtain their <br />water from the tank. The water users consume about 40 gpm during the <br />winter. The 500,000 gallon tank has about an eight day supply. Therefore <br />the water supply to the Pitkin Mesa water users will not be interrupted. <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 />PR -14 2.05-157- 03/14 <br />