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Item <br />Predicted impact <br />in permit <br />application <br />Observed impact <br />Prediction accurate? <br />Vertical <br />subsidence <br />magnitude <br />Maximum 18.4 ft. <br />in two -seam mining <br />areas. Less than 1 <br />ft. near panel edges <br />in single -seam <br />mining areas. <br />Between 2000 and 2007 visual <br />o bservations were used for verifying <br />the conceptual subsidence model, <br />rather than quantitative monitoring. <br />nn <br />The Spring 2010 report included <br />p g p <br />data from pre - mining surveys of <br />panel E -1 and the thalweg of the Dry <br />Fork of Minnesota Creek. <br />Postmining surveys will be <br />conducted after Panel E -1 and the <br />Dry Fork are undermined. <br />_ <br />Survey data and calculations in Appendix B of the Spring 2010 report <br />determined a maximum predicted E -Seam angle of draw of 19% (Memorandum <br />revised February 1, 2011 in Appendix B of Spring 2010 Subsidence Report). <br />This value is within the predicted range for E Seam mining of 8 to 21 degrees. <br />Horizontal <br />displacement <br />magnitude <br />Maximum <br />horizontal strain of <br />3.9% <br />Angle of draw <br />8 — 21 degrees <br />USFS roads <br />Rockfalls, cracking <br />Yes <br />USFS ponds <br />Draining <br />No new undermining of USFS ponds <br />since previous report (Spring 2010). <br />No new draining observed from <br />previous undermining. <br />Yes <br />or structures <br />3 <br />