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,.. <br /> <br />STATE OF COLORADO <br />DIVISION OF MINERALS AND GEOLOGY <br />Department o(Natural Resources <br />131 3 Sherman 5~.. Room 215 <br />Denver, CO 80203 <br />Phone: (3031 866-3567 <br />FAX: (303)872-8106 <br />March 16, 1993 <br />Attn: Colin etewart <br />Cyprus Empire Corporation <br />Eagle Coal Mine <br />P.O. Hox 68 <br />Craiq, CO 81625 <br />Re: Subsidence Reports Review from 6/91 to 12/92 <br />Eagle No. 6 Mine (C-81-044) <br />Dear Mr. Stewart: <br />of Soto <br />tie, <br />Me ^j///~~~ <br />M ~h <br />~ re l6 ~ <br />Roy Ramer <br />Governor <br />Michael B. Long <br />Division Director <br />2 have concluded my review of the three subsidence reports from <br />June 1991 to December 1992. Thank you for your cooperation in <br />forwarding them to me. Below are mentioned my comments, with <br />recommendations together with a summary of our phone conversation <br />and agreements to be added in the next subsidence report. <br />I. Report Comments <br />A. Monument Review <br />1. 5 Series <br />The pre-mining elevation figures differ from 6-12/91 <br />report to the 1-6/92 report. Reason is unclear why these <br />figures differ as they are baseline numbers and should <br />theoretically be a constant. Differences range from a <br />minimum of 2 to a maximum of 5 feet. This is a <br />significant difference in that it is from the 'baseline <br />figures from which the actual subsidence calculations are <br />made. <br />Recommendation: ' <br />Please clarify why the numbers from succeeding reports for the <br />baseline figures do not match. Or provide an explanation as <br />to why the difference exists. <br />2. A Series <br />The Division is unable to determine total subsidence to <br />date as no records exist showing the original elevation. <br />In addition, monument A8 has not been surveyed since July <br />1991. <br />