Laserfiche WebLink
iiiniiuiiuiuiu <br />999 <br />• • <br />STATE OF COLORADO <br />DIVISION OF MINERALS AND GEOLOGY <br />Deparimenl of NaNral Resources <br />131 J Sherman St., Room 215 <br />Denver, Colorado 80203 <br />Phone. (303) 866-3567 <br />FAX: (303) 832-8106 <br />September 8, 1999 <br />Mr. Mike Altavilla <br />Seneca Coal Company <br />P.O. Drawer 670 <br />Hayden, CO 81639 <br />RE: Yoast Mine (C-94-082); Permit Revision No. 1 <br />Dear Mr. Altavilla: <br />DIVISION O F <br />MINERALS <br />GEOLOGY <br />RECLAMATION <br />MINING•gAFETY <br />Bill Owens <br />Governor <br />Reg E. Walther <br />E.eculive Dnecwr <br />Michael B. Long <br />Division Dmean. <br />The Division has concluded its review of Seneca' Coal Company's (SCC) <br />responses to our technical adequacy questions which were provided in a letter <br />dated July 15, 1999 and the reclamation cost estimate which was provided by <br />SCC on June 24. The numbered comments below correspond to the comments <br />in the Division's August 31, 1999 letter. <br />36. SCC provided stability analyses for ponds 013 and 014. The analysis <br />indicates that the embankment of pond 013 will have a minimum static safety <br />factor in excess of 1.5. The Division has no further concerns regarding the <br />designs for pond 013. We would like to remind SCC that the engineering reports <br />discussed in the "Recommendations" sections of the stability analyses should be <br />submitted to the Division with the as-built certifications for the ponds, if not <br />before. If conditions different than those assumed in the analyses are <br />encountered during construction, we suggest that SCC contact the Division <br />immediately to discuss subsequent plans and construction. <br />The stability analysis for pond 014 indicates a minimum static safety of 1.4. As <br />discussed in the Divisions' original comment, Rule 4.05.9(3)(a) requires a <br />minimum static safety factor of 1.5 for impoundments with embankments in <br />excess of ten feet. Please refer to the original comment #36 and provide an <br />analysis or modified construction plans which result in a minimum static safety <br />factor of 1.5. <br />37. Response accepted. <br />We do suggest that the height of the primary riser and length of primary <br />spillway barrel be included with the as-built certifications for the ponds. <br />