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1 <br /> Figure 20 <br /> Subsidence Calculations, MC-10-16 Series Monitoring Points, Longwall 102. <br /> • <br /> Longwall 102 face estimated at 3,281 ft from startline, 8/9/85. <br /> Distance from face to last subsided point on 8/9/85 (MC-13) : 743 ft. <br /> Distance from face to first stable point on 8/9/85 (MC-14) : 921 ft. <br /> Surface elevation MC-13: 11 ,614 ft; MC-14: 11,590 ft. <br /> Estimated mine elevation on projection of MC series points: 8,852 ft. <br /> �------921 ' (x 43- t x Yq <br /> �--178'� _ <br /> MC-1 � - 3— h2 <br /> H <br /> \ h1 no scale <br /> 1 a <br /> 92 A longwall 102 <br /> A bed <br /> • A-B bed <br /> Projected vertical depth to coal at face (H) : <br /> H = h 1 + h 2 <br /> h1= (elev. MC-14) - (elev. face) <br /> =11,590 - 8,852 <br /> = 2,738 ft <br /> h2= 11tanO <br /> 24 0 = tano173 <br /> MC-14 173 = 7.90 <br /> h2= 921tan7.900 <br /> = 128 ft <br /> H = 2,738 + 128 <br /> = 2,866 ft <br /> • All calculations performed on HP-97 to 9 decimal places and rounded. <br />