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\ _ - <br />III IIIIIIIIIIIII III <br />STATE OF COLORADO <br />DIVISION OF MINERALS AND GEOLOGY <br />Department of Natural Resources <br />1313 Sherman 51., Room 215 <br />Denver, CO 80203 <br />Phone (303) 866-3567 <br />FAX. (303) 832-8106 <br />DATE: October 18, 1993 <br />TO: Christine Johnston <br />FROM: Jim Pendleton <br />pF COO <br />tip. <br />. ~g: <br />„e// <br />r8 i6 ~ <br />Roy Romer <br />Governor <br />Michael 9. Long <br />Division Dveuor <br />RE: West Elk M{neS~fiu-Annual Subsidence Report, September '93 <br />(Permit No: C-80-00'n <br />In response to your request, I have reviewed the Mountain Coal <br />Company's semi-annual subsidence report dated September, 1993. The <br />format of the report and attached map and cross-sections is <br />generally well done. I would offer several suggestions. <br />The extreme topographic relief at the site makes the vertical scale <br />of the cross-sections relatively non-informative. Perhaps a <br />separate vertically aligned "Amount of Subsidence" portion of <br />cross-section display would allow a more detailed and informative <br />depiction of the subsidence. <br />The primary purpose of semi-annual subsidence report is to monitor <br />the progress of subsidence at the mine site. Their secondary <br />purpose is to compare the manifestation of subsidence with the <br />projection forwarded by the operator in the permit documents. To <br />facilitate comparison with the original permit's subsidence plan <br />projections, it would be helpful if the projected subsidence <br />profile was depicted on the cross-sections. <br />The subsidence at the site to date appears to be consistent with <br />permit projections, for both the F and B Seams separately and <br />superimposed. <br />If you desire any additional comment please do not hesitate to <br />contact me. <br />cc: David Berry <br />