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STATE OF COLORADO <br />DIVISION OF RECLAMATION, MINING AND SAFETY <br />Department of Natural Resources <br />1313 Sherman St., Room 215 <br />D O <br />O <br />O <br />Denver, Colorado 80203 i <br />l ON <br />D <br />Phone: (303) 866-3567 RECLAMATION <br />FAX: (303) 832-8106 M I N I N G <br /> <br />February 2, 2011 SAFETY <br />Kathleen G. Welt John W. Hickenlooper <br />Mountain Coal Company, LLC Governor <br />P.O. Box 591 Mike King <br />Somerset, CO 81434 Executive Director <br /> Loretta E. Pineda <br />Re: West Elk Mine Director <br />Technical Revison No. 124 (TR-124) <br />Addition of Maximum Projected Areal Extent of Potential Mining <br />Dear Ms. Welt: <br />The DRMS has reviewed your letter of January 28, 2011 in which you responded to our adequacy review letter of <br />January 20, 2011. <br />Your responses to our previous comments 1 through 9 are adequate. We have follow-up comments regarding our <br />previous comments 10 and 11. <br />10. Please revise Map 51 to show a 20-degree angle of draw around the perimeter of the workings. Please use <br />the method of determining vertical distance that is explained in our letter of January 27, 2011 regarding <br />Appendix B of MCC's Spring 2010 subsidence report. A 20-degree angle of draw is appropriate based on <br />the 18.4-degree value at Station 101 of the Appendix, plus an assumed additional amount of 10% to <br />recognize the maximum angle of draw at a location may be greater than 18.4 degrees. Also, please change <br />the wording in the Map 51 legend that begins with "Approximate limit of the maximum" to the following: <br />Subsidence boundary at 20° angle of draw using the greatest vertical distance in each <br />projected mining area (vertical distance is the elevation difference between the <br />projected edge of the subsidence basin on the land surface and the nearest edge of the <br />longwall panel). <br />11. The DRMS considers the proposed updating of Map 51 with only the Annual Reclamation Report to be <br />too infrequent for DRMS to adequately evaluate subsidence impacts. The proposal to not update the <br />permit copy of Map 51 would not meet compliance with Rule 2.03.2(1), which requires information in the <br />application to be current. The DRMS reiterates its original request to add to the permit application a <br />commitment to submit along with each semi-annual subsidence report an application for a Minor Revision <br />that updates Map 51 with all actual workings in the Projected Potential Mining Area. <br />Sincerely, <br />Tom Kaldenbach <br />Environmental Protection Specialist <br />cc: Dan Hernandez, DRMS <br />Office of Office of <br />Mined Land Reclamation Denver • Grand Junction • Durango Active and Inactive Mines