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STATE OP COLORADO HiCn ~Hn D ~.i,w ~.i„n, <br />DEPARTMENT OF NATURAL RESOURCES <br />D. Monte Pascoe, Ezecu Live Director <br />III IIIIIIIIIIIII III <br />999 <br />~'ILNED LAND RE(:LAIVtA'I'ION <br />423 Centennial Building, 1353 Sherman Street <br />Denver, Colorado 80203 Tel. (303) 866-3567 <br />David C. Shelton <br />Director <br />September 15, 1982 <br />TO: Dan Mathews '~ <br />(/ i ^.~~-{~ <br />FROPf: Jim Pendleton _~ ,-', _.t„~yf/.~_ <br />/- /'j <br />RE: Subsidence 9oni~oring above the Bear No. 1 and No. 2 Mines and <br />its implica ions for the Bear No. 3 Mine <br />I have completed a review of the 1979 through 1981 subsidence monitoring <br />survey data submitted by Bear Coal Company for the monuments installed <br />above the Bear No. 1 and No. 2 underground coal mines. The results <br />indicate a relatively random movement of the monuments during that period. <br />These results may be indicative of inadequacy of the installed survey <br />monuments. Potential significant movements appeared to occurred at <br />monuments no, 3 and no. 13. Monument no, 3 appears to have moved .62~feet <br />down, .214 feet laterally to the north and .015 feet laterally to the <br />east. bl0nument no.. 13 appears to have moved 1.01 feet vertically downward, <br />2.02 feet laterally to the north and .99 feet laterally to the east. <br />Both of these.locations overlie fairly recent underground workings within <br />the Bear No. 1 and No. 2. Both demonstrate predominantly downslope movement, <br />which may or may not be related to ground surface subsidence. The data <br />is inadequate to correlate the observed movements with subsidence response. <br />Bear Coal Company is currently preparing to mine coal within the neighboring <br />Bear No. 3 underground coal mine. Stipulation no. 15 of the permanent program <br />permit No. C-033-81 calls for Che development of an appropriate subsidence <br />tronitoring program and the installation of appropriate subsidence monuments <br />above the proposed underground workings of the Bear No. 3. The stipulated <br />subsidence monitoring program submission was to have occurred within 30 days <br />following permit approval. The company has failed to meet that deadline. <br />I recommend that we advise the operator that submission of this plan is <br />required as soon as possible. The operator's attention should be called <br />to the findings document for a discussion of the reasons for monitoring, and <br />the minimum constituents of an appropriate subsidence monitoring program, <br />Cc: Brian F/unSOn <br />/ys <br />