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• APR °I- 951M1IuNl 15 dii 11'RIGHT H'.~TER TEL bU; d3ii Iii?ii <br />PRIVILEGED <br />AND CONI'YDENTIAL <br />MEMORANDUM <br />TO: Ms. Kathy Welt, Mountain Coal Company <br />I <br />FROM: John Rold, Consultant, Wright Water Engineers <br />DATE: April 17, 199 <br />RE: Subsidence Crack in the Lone Pine Area at West Elk Mine <br />P IIII? <br />The following memorandum, as per your request, is for a suggested response to the March <br />8, 1995 letter from Ms. Christine E. Johnston of the Office of Mined Land Reclamation <br />of the Colorado Division of Minerals and Geology (CDMG). <br />1 accompanied Ms. Johnston of the CDMG and Mr. Norm Every of Mountain Coal <br />Company (MCC) to inspect the subject crack at West Elk Mine on September 27, 199<l. <br />This memo relies on that visit, a review of field notes and photos taken at that time, and <br />reports of Mr. Norm Every's revisit to the crack on March 2?, 1995. The described crack <br />occurs near the midpoint of the south line of Sectio^ 17, T135, R90W on a high spin <br />ridge approximately ~OO~feet topographically above and north of the meadow and the old <br />cabin remnants at the Forks of Lone Fine Gulch. The described crack is the largest <br />(widest) of a lineaz family of smaller cracks which extend east-west discontinuously for <br />approximately 150 feet. 1The cracks partially cross the spur ridge between two prominent <br />cliff forming sandstones, topographically and stratigraplucally above and below the crack. <br />The description of the cr ck as being "~ feet wide, ~U feet long and 30 feet deep" taken <br />at face value would be ~arminG. A fuller description of [he crack puts it in a truer <br />perspective. <br />The 5-foot width pertains to e maximum width of the crack. Only a <br />short portion (10 to 15 feet) o that crack extent was 5 feet wide. Much <br />of tJre crack widt~l was Drily 6 to 18 inches wide. <br />1~he 30-foot depth of the crack was reported by MCC surveyors who <br />reportedly were able to extend a tape that far down along a portion of the <br />crack. Last fall when we visited the crack, a small portion of the crack <br />(approximately 12 to 18 mches in diameter) in the western corner of die <br />widest part of the crack. was the only portion of the crack more than 2 to <br />5 feet deep. That deep portion of the crack looked almost like a vertical <br />U <br />Z <br />vi <br />cc <br />W <br />W <br />Z <br />U <br />Z <br />t,u <br />cc <br />W <br />Q <br />H <br />z <br />U <br />3 <br />