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iiiiiniiiiiiiiiiu <br />STATE OF COLORADO <br />DIVISION OF MINERALS AND GEOLOGY <br />Department of Natural Resources <br />I } 13 Sherman SI ,Room ? l i <br />Denver, Colorado d0?01 <br />Phone 1103) d66-3567 <br />FAX: (fOJI dl~-fl106 <br />October 1, 1997 <br />~~~ <br />DEP,°,RTMENT OF <br />NATURAL <br />RESOURCES <br />Mr <br />Richard Mills <br />. Roy Romer <br />Twentymile Coal Company cn.r~nnr <br />29515 Routt County Road No. 27 lames 5. LnchheaJ <br />Oak Creek, CO 80467 Exewnve Durcior <br /> M¢hael B. Lone <br /> Drvnino Dvenor <br />Re: Foidel Creek Mine, C-82-056, Technical Revision No. 29 <br />Dear Mr. Mills: <br />The Division has conducted preliminary review of Twentymile Coal Company's application for Technical <br />Revision No. 29. The following concerns were identified during our review: <br />1. Approved Map 23A, dated 3/3/97, shows longwall panel No. 5 terminating 1375 feet east of the <br />Routt County Bridge #927, and longwall panel No. 6 terminating 812 feet east of Routt County <br />Road 27. This approved plan leaves the county bridge well outside the projected angle of <br />subsidence. Proposed Map 23 (dated 8/11/97) depicts longwall panel 6 terminating either 156 feet <br />east of Routt County Road No. 27 or 125 feet West of the intersection of Routt County Roads 33 <br />and 27. Two panel ends are included on Map 23 (dated 8/l t/97) submitted to the Division. <br />a. Which is the correct panel terminus? <br />b. Either of the depicted panel end locations would place Routt County Bridge No. 927 <br />within the subsidence angle of draw. Has Twentymile Coal Company received <br />permission from Routt County to subside this structure? <br />c. Routt County Bridge #927 overlies the proposed configuration of 5 Right Gateroad on <br />Map 23. Reference to Foidel Creek Mine First Half 1997 Subsidence Report <br />demonstrates that monitoring over 9 Right gate road experienced 1.52 feet of subsidence. <br />The Division would project that 5 Right gateroad could experience a similar amplitude of <br />displacement as well. The bridge is not on the list of structures projected to be affected <br />by subsidence, nor is there a discussion of impacts of the bridge as a result of subsidence. <br />Please include the bridge and discussion of impacts on revised pages, or, as was CDMG's <br />understanding, change Map 23 to illustrate that the bridge structure is outside the angle of <br />draw. Please describe the subsidence control plan and monitoring plan for the bridge. <br />(Rule 2.05.6(6)(f)) <br />2. Proposed Mine Plan Map No. 23 shows that Routt County Road No. 27 will be within the planned <br />subsidence zone. The Twentymile Sandstone outcrop laying east of Routt County Road No. 27 <br />will be subsided as well. Due to the proximity of the road to the outcrop, approx. 875 k., and the <br />steepness of the slope between the outcrop and the road, how does Twentymile Coal Company <br />propose to protect Routt County Road No. 27 from rockfall? Please explain how Twentymile <br />