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Subsidence Evaluation for the <br />Exhibit 60E Southern Panels, Apache Rocks West, & Sunset Trail Mining Areas Page 13 <br /> <br />831-032.923 Wright Water Engineers, Inc. <br />December 2021 <br />1. Maximum vertical displacement above the chain pillars (Scp) is expected to range <br />from 0.9 to 2.7 feet (0.1 to 0.3t) where the extraction thickness is 9 feet, and from <br />1.4 to 4.2 feet (0.1 to 0.3t) where the extraction thickness is 14 feet. <br />2. Maximum vertical displacement above the mined longwall panels (subsidence, Sm= <br />a • t) is projected to range from 5.4 to 7.2 feet (0.6 to 0.8t) where the extraction <br />thickness is 9 feet, and from 8.4 to 11.2 feet (0.6 to 0.8t) where the extraction <br />thickness is 14 feet. <br />Overburden depth above the projected B-seam longwall centers ranges from approximately 600 to <br />1,500 feet. With a projected longwall panel width of approximately 1,080 feet, maximum <br />subsidence (vertical displacement Sm = a • t) is predicted as follows (Table 2) for the Southern <br />Panels mining area of panels B26 to B29: <br />• Panels B26 to B29: These longwall panels range in width from subcritical to supercritical <br />(width-to depth ratio (W/d) ranges from 0.72 to 1.80). <br />1. Maximum vertical displacement above the chain pillars (Scp) is expected to range <br />from 0.9 to 2.7 feet (0.1 to 0.3t) where the extraction thickness is 9 feet, and from <br />1.4 to 4.2 feet (0.1 to 0.3t) where the extraction thickness is 14 feet. <br />2. Maximum vertical displacement above the mined longwall panels (subsidence, Sm= <br />a • t) is projected to range from 5.4 to 7.2 feet (0.6 to 0.8t) where the extraction <br />thickness is 9 feet, and from 8.4 to 11.2 feet (0.6 to 0.8t) where the extraction <br />thickness is 14 feet. <br />The E-seam panels E1 to E5 and B-seam panels B26 to B29 occur on top of one another, but are <br />not stacked based on the current panel layout (Figure 1). Therefore, while the subsidence (vertical <br />displacement Sm = a • t) of the two seams is additive, the maximum subsidence due to mining in <br />each seam will not occur at the same location. The closer the alignment of the B-seam panel occurs <br />in a stacked manner relative to the E-seam panels, the more additive the maximum subsidence will <br />be. <br />The superposition of the subsidence curves for the longwall mining of the E-seam and B-seam <br />indicates that the combined maximum subsidence will be roughly 80 percent of the sum of the <br />maximums for each seam. To be conservative, the maximum for the two-seam mining will be <br />estimated by summation of the maximums for each seam. <br />1. Maximum vertical displacement above the chain pillars (Scp) due to both E-seam <br />and B-seam mining is conservatively estimated to be the summation of the <br />subsidence for each seam, as the chain pillars for the E-seam and B-seam are nearly <br />located on top of one another. For the two-seam panel area, the maximum vertical <br />displacement is estimated to range from 2.8 to 8.4 feet (0.1 to 0.3t) where the <br />extraction thickness is 14 feet. <br />2. Maximum vertical displacement above the mined longwall panels (subsidence, Sm= <br />a • t) for the B-seam and E-seam mining is projected to range from 10.8 to 14.4 feet <br />(0.6 to 0.8t) where the extraction thickness is 9 feet, and from 16.8 to 22.4 feet (0.6