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~ ~ ~iiiiiiiiiiiiiiiiiii^ <br />DEPARTMENT OF NATURAL RESOURCES <br />Davitl H. Getches, Executive Director <br />MINED LAND RECLAMATION DIVISION <br />DAVID C. SHELTO N, Director <br />Richartl D. Lamm <br />Governor <br />DATE: June 10, 1986 <br />T0: Randy Price <br />FROM: Jim Pendleton <br />RE: "Interacts n of Subs' nce and Landsliding, Bear Mine No. 3, Somerset, <br />Colorado" <br />I have completed a review of the above referenced report, prepared by Rocky <br />Mountain Geotechnical, Inc., consultant to Bear Coal Company. This report was <br />prepared in response to Stipulation No. 7, placed upon approval of Bear Coal's <br />permit by the Division. Stipulation No. 7 states: <br />"THE DIVISION DIRECTS BEAR COAL COMPANY TO COMPLETE A DETAILED ANALYSIS OF <br />THE POTENTIAL EFFECTS OF SUBSIDENCE UPON THE STATBILITY OF THE LANDSLIDE <br />DEPOSITS LOCATED ABOVE THE PROPOSED UNDERGROUND WORKINGS OF THE BEAR NO. 3 <br />MINE, OPPOSITE THE TOWN OF SOMERSET. BEAR COAL COMPANY SHALL INSTALL AND <br />MONITOR ADDITIONAL MONUMENTS ON THE LANDSLIDE DEPOSITS, IF NECESSARY, IN <br />ORDER TO OBSERVE THE POTENTIAL DISPLACEMENT OF THE LANDFORM. THE DETAILED <br />TECHNICAL ANALYSIS SHALL BE COMPLETED AND SUBMITTED TO THE DIVISION FOR <br />REVIEW AND APPROVAL. BEAR COAL SHALL LIMIT FURTHER EXTRACTION TO <br />DEVELOPEMENT ONLY, NOT TO EXCEED FIFTY PERCENT EXTRACTION, IN ACCORDANCE <br />WITH THE DETAILED PLATE INCLUDED ON THEIR REVISED 'MINE PLAN' MAP, MAP <br />N0. 9. NO RETREAT MINING SHALL OCCUR WITHIN THE REMAINING PORTIONS OF THE <br />BEAR N0. 3 MINE, PRIOR TO THE RECEIPT OF WRITTEN APPROVAL FROM THE <br />DIVISION. IF SUBSIDENCE MONITORING EXPERIENCE FOR THE DETAILED STABILITY <br />ANALYSIS INDICATES THAT RETREAT EXTRACTION WOULD ADVERSELY EFFECT THE <br />STABILITY OF THE LANDSLIDE DEPOSITS OPPOSITE THE TOWN OF SOMERSET, THEN BEAR <br />COAL COMPANY SHALL SUBMIT A REVISED LIMITED EXTRACTION MINE PLAN FOR THE <br />BEAR N0. 3 MINE, DESIGNED TO PRECLUDE DISRUPTIVE DIFFERENTIAL SUBSIDENCE OF <br />THE LANDSLIDE DEPOSITS." <br />In compliance with that stipulation, Bear Coal has prepared and submitted the <br />above referenced report to the Division for review and approval. This report <br />includes analyses of land sliding and subsidence within and adjoining the Bear <br />No. 3 permit area. The report concludes that both short-term, temporary, and <br />long-term, permanent, effects of subsidence upon land sliding may be expected <br />above the Bear No. 3 Mine underground workings. "The short-term effects are <br />primarily associated with the developement of tensile ground strain and the <br />`;:~ <br />\ 423 Centennial Building, 1313 Sherman Street Denver, Colorado 80203 Tel. (303) 866-3567 <br />