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Subsidence Evaluation for the <br />Exhibit 60E South of Divide and Dry Fork Mining Areas Page 3 <br />2.0 MINING METHOD <br />The longwall mining method will be utilized in the South of Divide and Dry Fork mining areas. <br />The planned panel design is similar to the B -seam longwall panels of the West Elk Mine, where <br />subsidence measurements were used to obtain the baseline data that were used in this report. A <br />range of 8 to 14 feet of coal will be extracted from the E -seam (Figure 1). The extraction <br />thicknesses are projected based on exploration hole data; actual thicknesses may vary depending <br />on mining conditions encountered. <br />E -seam longwall panels El through E8 are projected to be 1,080 feet wide and extend up to <br />approximately 19,000 feet in length. Panel E9 is projected to be 1,080 feet wide and 5,750 feet <br />long. The panels will be mined by the retreat longwall mining method. Panels E1 through E8 <br />will be longwall mined from east to west. Panel E9 is planned to be longwall mined from south <br />to north. <br />The trend of panels E1 through E8 is approximately N80 0 W. Panel E9 trends roughly N10 °E. <br />The overburden depth above the panels E1 to E4 ranges from roughly 375 to 1,800 feet, whereas, <br />the overburden depth for panels E5 to E8 ranges from 500 to 1,800 feet. The overburden above <br />panel E9 ranges in thickness from 500 to 600 feet. <br />All longwall panels are planned to be separated by two or three rows of chain pillars. The row <br />nearest to the headgate side of the panels is projected to be a rigid pillar design — typically on <br />centers of about 125 feet wide by 200 feet long. The row on the tailgate side of the panel will be <br />of a yield pillar design — typically on centers of about 75 feet wide by 200 feet long. A barrier <br />system, about 700 feet wide, is currently projected to separate longwall panels E1 to E4 from <br />longwall panels E5 to E8. These mine plans and pillar designs may change as mining <br />experience, geological - geotechnical conditions, and /or mine operational procedures dictate. <br />831 - 032.810 Wright Water Engineers, Inc. <br />