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Vest Elk Mine <br />• Tilt above the western panels, for E Seam mining only, is projected to range from 0.017 on the <br />higher ridge areas to about 0.048 in the lower areas of Horse Gulch. Following completion of E and <br />B Seam mining, tilt is projected to range from about 0.033 on the higher ridges to 0.085 in Horse <br />Gulch. <br />Box Canyon Minim Area - Maximum tilt, based on analyses of West Elk Mine subsidence <br />measurements, is projected to range from 0.004 beneath West Flatiron to 0.035 above the <br />northernmost panel beneath Box Canyon. <br />South of Divide Mining Area and Dry Fork Lease Area - Tilt above the nine longwall panels <br />(panels El-E9) within the South of Divide mining area is projected to range between 2.2 and 2.3 <br />Sm/d for coal extraction thickness ranging between 8 and 14 feet. These values are based on <br />subsidence measurements at West Elk Mine (Table 1, and Figure 5 of Exhibit 60B). As <br />represented in Table 2 of Exhibit 60B, the overburden depth above the longwall panel centers <br />ranges from 400 to 1,425 feet. <br />• Panels El to E8. Maximum tilt in these panels is projected to range from 0.007 to 0.037 (0.7 <br />to 3.7 percent) where 8 feet of coal is extracted, from 0.013 to 0.044 (1.3 to 4.4 percent) <br />where 12 feet of coal is mined, .and from 0.013 to 0.064 (1.3 to 6.4 percent) where a 14-foot <br />thickness of coal is mitred. <br />• Panel E9. Maximum tilt in this panel is predicted to range from 0.034 to 0.044 (3.4 and 4.4 <br />percent), where 12 feet of coal is mined and from 0.039 to 0.052 (3.9 to 5.2 percent) where <br />14 feet of coal is produced. <br />Maximum Curvature <br />Curvature, i.e., subscript (Cm) which is the reciprocal of radius of curvature (and thus expressed in <br />radians/foot [rad/ft]), is calculated front differential tilt. Maximum positive (convex upward) <br />curvature in the West Elk Mine monitoring network is as much as 50 percent more over chain <br />pillars than it is above longwall panel boundaries. Maximum positive curvature at the current West <br />Elk Mine ranges fiom 14.4 to 18-(Sn,/d') with a numeric range of 0.000060 to 0.000065 rad/ft above <br />longwall panel boundaries to an average of 24-(S,,,/d) with a numeric range of 0.000144 to 0.00022 <br />rad/ft above the chain pillars. <br />Maximum negative (concave upward) curvature averaged about the same when measured above the <br />chain pillars as it did above the panel boundaries. Maximum negative curvature ranges from about <br />-20 to -25-(Sn,/d2) (-0.000111 to -0.000066 rad/ft) above longwall panel boundaries and has an <br />average value of -24 (Sm/d') (-0.00012 to 0.00025 rad/ft) in the panel centers between the chain. <br />pillars. Maximum positive and negative curvature in four different areas of the Western United <br />States ranges from 9 to 45 (S,,,/d`). l-ai-Kirr_um curvature ranges are given below for the eastern and <br />western panels of the Apache Rocks and the Box Canyon mining areas. <br />Apache Rocks Mining Area - Maximum positive curvature projected for B-Sear mining in the <br />eastern panels of the Apache Rocks mining area (using an average West Elk Mine value of <br />• 24 (S,,,/d')), ranges fiom 0.000023 to 0.00025 rad/ft; maximum negative curvature (using a similar <br />average of -24-[S,,,/d']) ranges from -0.000033 to -0.00069 rad/ft. Maximum positive curvature <br />2.05-130 Revised June 200.1 PRIG. Rev. Afarch 2006:.Ala), 2006 PRI G, Alov. 2006TR107,Apri12007TR108. Sep. 2007 PR12; Feb. 2008 PR-12