Laserfiche WebLink
West Elk Mane <br />The Box Canyon permit revision azea encompasses the remainder of the Box Canyon lease tract. Only <br />B Seam mining is planned in this azea. Except as noted, the following discussion of mining, geology <br />and subsidence impacts for the Box Canyon Mining azea apply to Pane125, in Sylvester Gulch. <br />West Flatiron Minine Area -- This azea is designated on Map IA and includes extensions of longwall <br />panels 18A, 18, and 19. <br />South of Divide Minine Area -The mining area encompasses the E Seam longwall panels located <br />primazily in Sections 32, 33, and 34 of Township 13 South, Range 90 West of the 6`h Principal <br />Meridian, and Sections 3, 4, and 5 of Township 14 South, Range 90 West of the 6"' Principal <br />Meridian. The panels are identified as El through E9. <br />South of Divide Permit Revision Area -The permit revision area is indicated by the regulatory <br />boundary added to the mine permit, as shown on Map lA. <br />Critical Mining Width -The width of a mining panel necessary for maximum subsidence to occur; <br />the length of the panel must also be greater than, or equal to, critical panel width for maximum <br />subsidence to occur. Critical width (Wer) commonly ranges from 1.0 to 1.4 times the overburden <br />depth (d). <br />Subcritical Mining Width -The width of a mining panel less than critical width (i.e., less than 1.0 to <br />1.4d). <br />Supercritical Mining Width -The width of a mining panel greater than critical width. <br />Table 42 <br />Definition of Subsidence Terms <br />S mbol Definition Dimensions <br />S Vertical Dis lacement (Subsidence) L <br />Sm Maximum Vertical Dis lacement (Sm a4) L <br />S/Sm Ratio of Vertical Displacement to Maximum Vertical <br />Dis lacement L/L <br />Sn Horizontal Dis lacement L <br />t Coal Extraction Thickness L <br />a~Sm/t) Subsidence Factor L/L <br /> Subsidence Factor above Chain Pillars L/L <br />S = ~t Maximum Subsidence Above Chain Pillars L <br />d Overburden D th L <br />5,,,/d Ratio of maximum vertical dis lacement to overburden de th UL <br />WQ Critical Extraction Width L/L <br />W/d Minin Width to Overburden De th Raio UL <br />M Tilt (Slo e) UL <br />Mm Maximum Tilt UL <br />C Curvature, the reci rocal of Radius of Curvature rad/L (1/L) <br />Cm Maximum Curvature rad/L (1/L) <br />E Horizontal Strain (+) is Positive, (-) is Negative UL <br />Em Maximum Horizontal Strain L/L <br />~ Angle of Draw Degrees <br />B Break An ]e De ees <br /> Angel of Major Influence Degrees <br />r Radius of Major Influence L <br />1.05-105 Revised June 1005 PRIQ Rev. Morch 1006; Rev. Apri12006 PR/0; May 1006 PRIQ T'ov. 1006 TR107 <br />