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iii iiiiiiiiniiiiii <br />999 <br />STATE OF COLORADO <br />DIVISION OF MINERALS AND GEOLOGY <br />Depanmenl of N~tu rat Resources <br />1311 Shcrm, n SL, Room 215 <br />Denver, Colorodu 8020] <br />Phone 1303) 866]567 <br />FAX. U03183L8106 <br />March 17, 2000 <br />Mr. Mike Refer <br />CAMAS CO. Inc. <br />3605 S. Teller St. <br />Lakewood. CO 80235 <br />RE Final Review of Slope Stability Analysis for New 112 Reclamation <br />Permit Application, Permit No. #M-99-098, Riverview Resources <br />Dear Mr. Refer, <br />DIVISION OF <br />MINERALS <br />GEOLOGY <br />RECLAMATION <br />MI NING•SAFETY <br />aill Owens <br />Co.ernor <br />Creg E Walther <br />E~ecuove Dveaor <br />Michael B. Long <br />Division D~reclor <br />This letter is being written to address the Division of Minerals and Geology's (DMG's) final review of the Slope <br />Stability Analysis submitted March 9, 2000, for the new 112 application submitted by your company, Permit No. <br />#M-99-098, Riverview Resources Pit. On March 6, the Division included the followine in our letter recommending <br />approval of the application: <br />The setback of 200' from all structures must be observed, as specified under Rule 6.4.19, unless an adequate <br />engineering analysis is submitted to DMG no later than 4 p.m. March 9, 2000. The setback From structures may be <br />determined by the Division to be less than 200' based upon such an engineering analysis. Should no analysis be <br />submitted to DMG by the time and date specified, then the 200' setback must be maintained until such time as a <br />technical revision to the permit is submitted and approved by the Division. <br />Since the Division received the analysis within the specified time period, we reviewed the submittal for the technical <br />adequacy of the factor-of-safety analysis for excavations at 20' and 42' depths. At a depth of 20', the proposed <br />setback of 40' proved to be adequate, yielding a factor of safety of I.OS, when measured from the toe of [he <br />excavated highwall. The 42' highwall excavation, however, required an 80' setback from [he toe of the mined face in <br />order to achieve an acceptable safely factor of I.00. A written commitment to these setbacks from all structures must <br />be submitted to DMG in order for us to change the currently accepted setback of 200'. Should the Operator mine any <br />deeper than 42 feet, a 2H:1 V length of setback will be required From the toe of the mine face. <br />Please confirm your acceptance of these setbacks in writing prior to the Board Hearing on March 22, 2000. If this is <br />not done prior to the Board Hearing, [he setbacks for the structures inside and adjacent to the permit area revers to <br />the previously agreed-upon 200 foot setback. <br />If you have any further questions, please feel free to contact me at (303) 866-3567. <br />Sincerely, <br />Christina L. KamniYcar <br />Environmental Protection Specialist <br />Cc: Carl B. Mount, DMG <br />Shani Eastin, Tuttle-Applegate Inc. <br />Connie Davis, CAMAS ~ ~ ' ~~ ' <br />US Fish &' Wildlife Service '~ ~ ~ ' <br />•~~ US~ArmyCorpsoPEngineers <br />Objection List <br />