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Revised 11/85 <br />• The anticipated extent of subsidence falls within the proposed permit <br />boundary. To the east of the Bear No. 3 permit area, the extent of <br />subsidence will fall outside the existing permit boundary. This area <br />has previously been mined (C coal seam) by the Bear No. 1 and No. 2 <br />mine. The subsidence line for Bear No. 1 and No. 2 falls within the <br />Bear No. 3 permit area. Since the Bear No. 3 Mine is a revision to the <br />Bear No. 1 and No. 2 Mine, the subsidence line is covered under this <br />application. <br />Subsidence Effect on Upper Coal Seams. Subsidence will have a minor <br />effect on the recovery of coal resources above the C Seam. Many case <br />histories of older coal mining districts indicate that recovery of coal <br />above lower mined out seams is possible. Seams have been mined above <br />lower mined out seams with partings of 50 feet or less. <br />The E and F Seams range from 180 to 410 feet above the C Seam. The <br />large parting should allow later extraction of the upper seams with only <br />• a slight increase in mining costs due to subsidence. <br />Areal type subsidence will ensure that the E and F Seams are subsided <br />more or less evenly over the mining area. Areal subsidence will further <br />ensure that the in situ stress fields in the E and F Seams after mining <br />of the C seam will be approximately the same as the stress field found <br />in the E and F Seams prior to mining of the C Seam. By employing areal <br />type subsidence and ensuring a minimum disturbance to the stress fields <br />in and around the E and F Seams, the effects on coal recovery in the E <br />and F Seams will be minimized. <br />Cost of coal recovery in the E and F Seams will probably be slightly <br />higher after the mining the C Seam than they would have otherwise been <br />had the seams been mined before the C Seam. The disturbances caused by <br />subsidence in the E and F Seams may result in disturbance to <br />pre-existing geologic discontinuities in the E and F Seams. Higher roof <br />. control costs in these areas may occur. In addition, lower coal <br />extraction in the E and F Seams around the geologic discontinuities. <br />The disturbance of pre-existing geologic discontinuities will not <br />-23- <br />