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2.05 <br />• 2.05.6 <br />A,F'PiSCATION FUR PERt~ffT FOR SURFACE OR UNDERGROUND MINIIQ(' ACTIVITIES <br />MiNaiLIIQ RFX,~UIItFS~Pl7.5 FUR OYf3tATION AND RECLAMATION PI.At~. <br />Mitigation of Surface Coal Mining Operation III~aCts. (Cont'd.) <br />(6) (c) (i) (B) (Cont'd.) <br />• <br />and 2600 ft. centers nor~~h-south. These stations are surveyed <br />once per year and provide general information on horizontal <br />and vertical displacement, yet do not provide specific <br />infor^.iaticn on draw angle. Score widely spaced grid monuments <br />will not yield furt~er information on subsidence. Either the <br />stations will not be undermined or surveying began too long <br />after secondary retreat mining and subsequent subsidence <br />effects were not detect~l. Stations 3, 4, & 5 have not been <br />undermined and CWI does not intend to undermine these <br />monuments. The remaining monuments (1, 2, 9, 10, & 11) were <br />surveyed initially after secondary retreat mining and future <br />information due to subsidence effects cannot be obtained from <br />these monuments because no movement has been detected. <br />Additional wide-spaced grid monitoring stations will be <br />constructed to analyze subsidence effects within the area of <br />the Orchard Valley West mine during the remaining permit term <br />(see Map 3-1). Monitoring stations 90, 92, and 93 will be <br />installed in 1987 to allow monitoring of the land within East <br />Reatcap Creek. Additional high resolution grids may be <br />emplaced in the Renewable Resource Lands to substantiate the <br />subsidence predictions described in Section (6)(b)(i)(B) <br />during future permit texas. These charx~es in monument <br />placement will be proposed in CrT2's "Annual Hydrology and <br />Subsidence Report." <br />Monitoring stations 28 through 69, and 201 through 224 <br />represent a high resolution network designed to portray site <br />specific data in varying geologic and topographic conditions. <br />Stations 201 through 224 are intended to depict draw angles <br />and any possible differential subsidence on alternating fault <br />bloc:ss. <br />These stations are also intended to depict subsidence effects <br />in varying topographic relief (refer to subsidence cross <br />sections in the Subsidence Appendix, Volume 3). <br />Stations 42 through 51 are intended to depict subsidence <br />effects inclusive of draw angle under conditions typical of <br />mast of the permit arm-'ncderate overburden and gentle <br />topography. <br />By November of 1988, C.dI felt that the major percentage of „ <br />expected movement had occurred within the close spaced grids <br />28-69 and 201-224. P.nalysis of the data available indicated <br />• TR 91-16 Revised 10/22/91 <br />146 <br />