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• days up to many years. The amount and timing of subsidence, 1f anyt ie <br />dependent primarily upon the structural characteristics of the overburden, <br />the thickness of the seam, the depth of the mining beneath the surface, the <br />percentage of coal extraction, and the width of.coal extraction areas. <br />Superimposed upon Map Exhibit II, are the areas where coal is to be <br />extracted in each of the 3 seams, the buildings and stock pond, and the re- <br />newable resource land, that is, the cleared property used for hay fields and <br />grazing. An examination of this map shows that the areas of potential damage <br />by subsidence are: <br />1. the buildings and stock pond. <br />2, the area of the Lower Pinnacle seam [o be mined in fault <br />blocks 1 and 2, which is partially overlain by a cleared <br />area used for grazing, and <br />3, the cleared land in fault block 3 where the cleared land <br />' partially covers the area where 2 and 3 seam mining ie to <br />be conducted. <br />Through the use of empirical data gathered from recent studies in <br />• subsidence of underground operations, which is summarized on Figures 1 and 2, <br />tl~e case histories indicate that Sunland's general plan to use the room and <br />pillar method of mining with maximum pillar extraction estimated to give an <br />SOX recovery might eventually cause subsidence [o the surface in some areas. <br />Tl~e geologic conditions at the mines studied reported that: <br />1. the coal seams were nearly flat lying, from 6-9 feet thick <br />and very uniform and continuous, <br />2. the bed rock was largely shale and silts tones with the im- <br />mediate roof material quite variable, and ranged in thickness <br />from 0-800 Ecet, <br />3. material a[ the surface was mostly glacial or glacially <br />derived seJlments from 0-65 Eeet In thickness,' <br />4. in general, the surface topography was nearly flat lying <br />to vary gently rolling. <br />The geologic conditions at the mines included in [he studies; relative <br />to Uw coal scam pat'ameC~rs and general surface topography, is similar to <br />' that of Sunland's. The big difference Ls in the overburden material in that <br />(99 <br />5 D. H. EMLING COMPANY <br />