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<br />planned under either the Williams Fork or the Yampa River. <br />However, it should be noted than an old abandoned mine exists <br />near the areas of confluence for the Williams Fork and Yampa, and <br />may have removed sufficient coal to induce subsidence (see Map <br />IV-12). <br />Mining of the seams in Eagle No. 5 and 9 t4ines will <br />result in roof fracture, caving and subsidence only in certain <br />planned areas. The remainder of the areas will experience no <br />roof fracturing. The maximum height of caving has been calcu- <br />lated to be approximately 98 feet where subsidence is planned <br />(see Section 9.6). Caving will result in increased vertical per- <br />meabilities within the maximum cave height and a drawdown cure in <br />that area; sandstones, shales and coals above the maximum cave <br />height may subside, but are projected to remain intact. An <br />increased amount of water has been factored into the inflow <br />formulas to account for this subsidence. Except for the materials <br />within 48 feet of the coal seam, there is expected to be no <br />change in the hydrologic characteristics of the overburden ma- <br />terials. Collapse of the roof materials will result in signi- <br />ficantly improved vertical connection between the coal and the <br />collapsed aquifers. <br /> <br />IV-74A Revised 05/16/80 <br />