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1 <br />R ~cnartl D Lamm <br />Governor <br />D~ARTMENT OF NATURAL RESOURCES. <br />D Mmgr P.i ;ror:. Exri; uli.c Dv Mloi <br />MINED LAND RECLAMATION DIVISION <br />DAVID C. SHELTO N, Director <br />~$ <br />MEMURANUUM <br />;; <br />T0: Gregg Squire <br />FROM: Jim Pendleton <br />RE: "Stability of <br />June 1983 <br /> <br />ast Highwall of the Chimney Rock Coal Mine" <br />I have reviewed the document referenced above. This report was <br />prepared by Fox Consultants, Inc., consultant to Chimney Rock Coal <br />Company. The report presents the result of a geotechnical investigation <br />of the southeast highwall at the Martinez Strip mine. This highwall <br />adjoins Colorado Highway 151. The company proposes to auger from this <br />highwall up to the right-of-way boundary of the state highway. The <br />Division imposed .a stipulation, in response to Colorado Department of <br />Highway comment, requiring the operator to complete an examination of the <br />hiyhwall prior to the commencement of augering activities. The purpose <br />• of this geotechnical investigation was to discern any geological factors <br />which might endanger the stability of the highway. <br />Fox's report, prepared by Paul V. Rosasco, conforms with the <br />prudent state-of-the-art of highwall stability analysis. It is thorough <br />and descriptive. Mr. Rosasco concludes; "... that the fracture sets <br />currently exposed within their highwall do not contain any unstable <br />planar or wedge configurations for which failure could affect the <br />stability of Highway 151. In addition, the timely placement to (of) <br />backfill in the pit against the final highwall should assure that a large <br />massive failure affecting the highway stability should not occur in the <br />future." <br />It is my recommendation that we approve Chimney Rock's request to <br />proceed with their proposed augering within the northeastern third of the <br />highwall, with the following conditions: <br />(1) Approval of the report and augering is also granted by the <br />Colorado Department of Highway District V Office; <br />(2) Placement of backfill within the pit occurs as irtmediately <br />following augering completion as 1s possible; and <br />(3) Additional examination and analysis be completed, and Division <br />and Colorado Uepartment of Highways approvals acquired, for the remaining <br />southeastern two thirds of the highwall, prior to the commencement of <br />augering within that additional area. <br />3^, <br />`}" i, <br />;:k v. <br />`'iir= <br />$it,' <br />cc: Ed Bischoff <br />Document No: 3870E <br />423 Centennial Building; 1313 Sherman Street Denver, Colorado 80203 Tel. (303) 866-3567 <br />