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Figure 23 <br /> • Subsidence Calculations Control Point TP-3 and 4-5 North Pillar <br /> Area , No. 5 Mine <br /> TP-3 is outside of the 4-5 North pillared area, worked in mid-1982. <br /> Point was not surveyed between installation in 1981. and 8/9/85; no <br /> movement since installation was detected. <br /> Distance from 5 North pillared area to TP-3 (x) : 680 ft. <br /> Surface elevation TP-3: 11 ,446 ft. <br /> Coal elevation, edge of 5 North pillared area: 9,360 ft. <br /> Surface elevation over edge of 5 North pillared area: 11,230 ft. <br /> Depth to coal (H) : 1,870 ft. <br /> TP-3 x <br /> ly <br /> H no scale <br /> A <br /> 4-5 North pillar area <br /> A-6 bed <br /> Slope angle (0) : _ Y <br /> 0 = tan lx <br /> = tan-1 216 <br /> 680 <br /> = 17.62° <br /> Apparent angle of draw to TP-3 (8; no subsidence detected) : <br /> 8 = tan-1 x <br /> Hcos20 <br /> = tan-1 680 <br /> 1870cos217.62 <br /> = tan-1 680 <br /> 1870 0.91 <br /> = tan-1(0.40) <br /> ° <br /> = 21.82 <br />