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are presented in Attachment A that show that a factor of safety of at least 1.3 was calculated <br /> using a slope of 1.5H:1V and 20-foot-wide benches for the proposed diversion channel. <br /> Conclusion <br /> The slope stability analysis indicates that regrading the reclaim fill to slopes of 1.5HAV with 20- <br /> foot-wide benches every 20 vertical feet results in an acceptable factor of safety for the <br /> diversion channel foundation. The foundation will primarily be placed on existing fill but if new fill <br /> is placed it should be compacted to 95% of maximum dry density and within 2% of the optimum <br /> moisture content as determined by standard Proctor (ASTM D698). The calculations presented <br /> herein were performed without site-specific obtained from a geotechnical investigation of the <br /> reclaim fill or highwall stability analysis. Addressing these data gaps would increase the <br /> accuracy of the calculated factors of safety. <br /> Maintenance and best management practices are recommended to keep the slope at this <br /> calculated factor of safety. Allowing for water infiltration into the reclaim fill would be the most <br /> detrimental to the factor of safety. Periodic inspections of the slope for signs of movement and <br /> groundwater within the reclaim fill are recommended. <br /> References <br /> 1. GEO-SLOPE International, Ltd., GeoStudio 2023.1. <br /> 2. DRMS, 2018. Policies of The Mined Land Reclamation Board. Colorado: Division of <br /> Reclamation, Mining and Safety, The Mined Land Reclamation Board. May 16. <br /> hdrinc.com 1670 Broadway, Suite 3400, Denver, CO 80202 <br /> (303)764-1520 <br /> 3 <br />