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between 5 and 28 inches, with the higher figures more likely to be near the <br />. outcrop. In fault block 3 where the 3 seam mining is proposed, it is estimated <br />that the maximum subsidence will probably be between 12 and 67 inches, and <br />that the average over the subsided area would be somewhere between 11 and 44 <br />inches, with the higher figures more likely to be near the outcrop. <br />The type of subsidence expected would be the gentle, trough type, as <br />opposed to the sink hole or pot hole type subsidence experienced in shallower <br />cover where competent roof material is not present. In all likelihood, if <br />subsidence did occur, if probably would not show up for several decades and <br />the amount probably would be toward the low side of the above figures. <br />It is concluded that any subsidence would have a negligible effect on <br />the renewable resource lands. <br />The final area of concern for potential subsidence damage is the building <br />structures and pond. Since the projection for maximum subsidence for zone 3 <br />in the deeper cover area is estimated to be between 12 and 49 inches, it ie <br />conceivable that at this higher level there could be some damage to these <br />structures. Ilowever, under the present plan for the sequence of mining, it <br />may be a few years before any mining would be conducted under the structures. <br />It is, therefore, proposed: should the buildings still be present at the time <br />mtning is to be conducted in this area, that a barrier pillar be left under the <br />buildings and pond, within which only a 50% recovery room and pillar method be <br />employed with the support provided by uniformly distributed pillars with <br />minimum dimensions of 20' x 30' and that there be no pillar extraction. It ie <br />estimated that a SO% recovery within this barrier pillar will cause little or <br />nu subsidence to the surface. 7'lie outline of the barrier pillar is shown on <br />Map Gxhibit 11, [hc di mansions of which arc: <br />1. zone 3 upper bed, 615' x 508' <br />2. Upper Pinnacle bed, 829' x 690' <br />3. l.owcr Plnnac7c bed, 871' x 72G' <br /> <br />20 3 <br />9 D. H. EMLING COMPANY <br />