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Harding Lewaon Asaoclates <br />III IIIIIIIIIIIIIIII <br /> <br />August 9, 1996 <br />Henry Barbe <br />Environmental Coordinator <br />Mountain Coal Company, West Elk Mine <br />P.O. Box 591 <br />Somerset, Colorado 81434 <br />SEP 0 3 1996 <br />Division of ,tit,nerars d Geology <br />RE: Survey Monitoring Data o(Mautz Cabin Above Lone Pine Gulch <br />Dear Mr. Barbe: <br />Six survey monitoring stations were established in December, 1994 in the vicinih~ of the Mautz <br />cabin above Lone Pine Gulch near Somerset, Colorado. Five stations were located around the <br />perimeter of the cabin and the sixth was located approximately 300 feet east-northeast of the cabin. <br />Just prior to and during undermining observations were made weekly. Post undermining <br />observations were made bi-monthly for [he neat six months until July, 1995, and [he final most <br />recent observation was made in June, 1996. Data has been digitally transferred and the results <br />have been tabulated, graphed, and are attached. <br />Movement is consistent and uniform within the survey margin of error for all of the cabin stations. <br />The behavior observed is expected from overburden subsidence caused by retreating longwall <br />operations. There were apparently three distinct time periods assoc,ated with movement: 1) Dec. <br />`94 -Feb. `95; 2) Mar. -Apr. `95; and 3) May -Jul. `9~. During the first period the stations <br />uniformly moved an average 2 inches north, I l inches east, and settled 9 inches. During [he <br />second period [he stations moved only a little, averaging 1 inch south, 2 inches west, and settling 1 <br />inch. During the third period the stations moved l3 inches north, then retreated south 9 inches, and <br />also moved 14 inches west and settled 14 inches. Since that time to the present the subsidence has <br />slowed considerably and now appears stabilized. Overall, the cabin moved as a unit. The position <br />of the cabin on June i, 1996 is generally 28 urches lower in elevation, 9 inches north, and l I inches <br />west of the surveyed pre-mining position on December 7, 1994. <br />Please contact either myself at (406) 933-802? or Charles Rehn at (80l) 363-445 if you have any <br />questions regarding this data. <br />Sincerely, <br />H wson Associ tes <br />~~ <br />Philip J. Meis <br />Senior Engineer <br />c~(~ ~ C <br />Charles C. Rehn, P.E. <br />Principal Engineer <br />Attachments <br />Engineering and 136 East Soulh Temple, Suite 1570, Salt Lake City, Utah 84n1 Telephone: (801) 363-4455 Telecopy: (001) 363-4476 <br />Environmental Services 1 AiFmdnv~ „/ HanG„¢.bmi ~nv~ • QQi~n Kun,~,m,d, <br />