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COLORADO <br /> Division of Reclamation, <br /> AV Mining and Safety <br /> Department of Natural Resources <br /> 1313 Sherman Street, Room 215 <br /> Denver, CO 80203 <br /> February 23, 2015 <br /> Jeremy Deuto <br /> GEI Consultants, Inc. <br /> 2625 Redwing Dr., Suite 370 <br /> Fort Collins, CO 80521 <br /> Re: Martin Marietta Materials, Inc., Greely 35th Avenue Mine, File No. M-1977-036 <br /> 112c Permit Amendment (AM-02) Application, Geotechnical Stability Analysis Review <br /> Mr. Deuto, <br /> The Division of Reclamation, Mining and Safety (Division/DRMS) staff has reviewed the stability <br /> analysis dated January 13, 2015. Using Clover Technology's Galena v6.1 slope stability <br /> software,the Division conducted further analysis of two critical slope area configurations for <br /> the Greeley 35th Avenue Mine. Specific comments and requirements for each of the cross <br /> sections are provided below. <br /> Slurry Wall Station 22+60 Section—Empty Reservoir <br /> 1. The Applicant's cross section was duplicated for verification. The safety factor produced by <br /> Galena is higher (3.77)than the safety factor produced by the Applicant's model (3.6). <br /> Additionally, the Division duplicated the cross section will a full reservoir. The safety factor <br /> produced by Galena was 3.54. Therefore, the accuracy of the Applicant's analysis is <br /> confirmed. Copies of the Galena models are attached. <br /> Slurry Wall Station 22+60 Section —Vertical Mining Slope <br /> 2. The Applicant's cross section was duplicated for verification. The safety factor produced by <br /> Galena is higher (2.38)than the safety factor produced by the Applicant's model (1.9). <br /> Therefore,the accuracy of the Applicant's analysis is confirmed. A copy of the Galena <br /> model is attached. <br /> Conclusion <br /> The Division agrees with the critical slope area configurations at the Greeley 35th Avenue Mine. <br /> The Applicant must understand any transgression of the sloping criteria will be considered a <br /> violation of the permit. <br /> o_F c��� \ <br /> 1313 Sherman Street, Room 215, Denver,CO 80203 P 303.866.3567 F 303.832.8106 http://mining.state.co.uis <br /> John W. Hickentooper,Governor I Mike King, Executive Director I Virginia Brannon, Director * 1876 <br />