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<br />• <br /> <br />2.05.6(6) <br />(f)(i) A description of the physical conditions, such as depth of cover, seam <br />thickness, and lithology, which affect the likelihood or extent of subsidence <br />is presented in Volume III, Exhibit 15. The depth of cover data is presented <br />on Map 27, Subsidence. <br />(f)(ii) <br />(f)(ii)(A) <br /> <br />PR-08 <br />APPRov~ <br />9/2-5/d3 <br />A narrative of the detailed description of the mining method and other <br />measures to be taken which may affect subsidence follows: <br />Room and pillar and longwall mining will be used for coal removal. The size <br />sequence and timing for development is presented on Map 14, Mine Plan. <br />Nearly all of the areas to be mined are areas in which planned-subsidence <br />mining methods will be used. There are a few exceptions to this statement <br />as outlined below. <br />In orderto protect against chimneysubsidence, only development mining will <br />be performed in areas with less than 110 feet of overburden. <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 water which 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 />2.05 - 106 - 07/03 <br />