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• 2.05.6(6) <br />The subsidence implications dealing with mining in low overburden areas <br />adjacent to the fault trace are a concern. The First North Mains mined into <br />the fault in late 1997 or early 1998. Additionally, the Operator has probe <br />drilled the fault on numerous occasions. The fault is characterized as a <br />shear fault as opposed to a roll fault and little fracturing was noted. The <br />probe drilling has not encountered any appreciable waterwhich indicates the <br />fault trace is virtually dry. <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, orotherfailure nearthe outcrop. See <br />Exhibit 15, Section 1.7. Zones Along Outcrop Barrier Pillar. <br />Dove Cave will be supported with timber posts prior longwall extraction under <br />the cave or within the angle of draw of the cave. Timber posts, four to six <br />inches in diameter, will be installed in Dove Cave on approximately five foot <br />centers with an emphasis on supporting the edge of the sandstone ledge. <br />The timber posts will be removed from Dove Cave two years after mining has <br />occurred. If after the two year period, the support timbers appear to be <br />taking on load, thereby providing the primary support for the overhand, the <br />Operator will consult with the USFS in order to determine future action and <br />long term support. In addition, if the timber supports do not appear to be <br />functioning properly, the Operator will contact USFS representatives <br />immediately to determine necessary steps to minimize resource damage. <br />• <br />PR-11 2.05 - 111 - 11/08 <br />ApPRov~ <br />