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Mr. Brennan Middleton <br /> September 30, 2022 <br /> Page 5 <br /> CONCLUSIONS <br /> The stability analysis results indicate the underdrain and the concrete ditch are both stable based of the Factors of <br /> Safety listed above. Factors of Safety at other structures with 200-feet of the mine slope will be greater because they <br /> are at a greater distance from the mine slopes than those summarized in the table above. <br /> LIMITATIONS <br /> Our review is based on regional geologic mapping, present mining conditions, and borehole data in some case <br /> performed by others. Stability analyses were performed using typical strength parameters for the various strata in the <br /> critical sections. Should the mining plans change or subsurface conditions vary from those portrayed in this letter, we <br /> should be contacted in order to re-evaluate the potential affects on permanent man-made structures. Stability analyses <br /> were run at the structure in question and were not run on failure surfaces closer to the highwall. Note also that <br /> surcharge loads due to temporary material stockpiles and overburden berms were not considered in the analysis. <br /> Please call with any questions or comments. <br /> Sincerely, <br /> Civil Resources, LLC <br /> Gary Linden, P.G. <br /> Senior Engineering Geologist <br /> Reference: <br /> Colton, R.B., 1978, "Geologic Map of the Boulder-Fort Collins-Greeley Area, Colorado", U.S.G.S. Map 1-855-G <br /> Attachments: <br /> U.S.G.S. Uniform Hazard Tool Earthquake Acceleration <br /> Galena Model Outputs: South and Southeast Sections <br /> J:0roonnfield-329\DRMS\Stabiity Analyses\Stability analysis-Heit.doc <br />