Laserfiche WebLink
AFS Response to DRMS Geotech Review#3 September 30, 2021 <br /> The purpose for conducting the sensitivity analysis and including the results in the Exhibit was to <br /> understand if slope stability should be reanalyzed if rock of lower strength quality is encountered <br /> during mining. Note that the material properties in the sensitivity analysis represent a <br /> hypothetical material of lower quality and outside of the collected data and parameters of the <br /> slope stability analysis. Given these factors and that a sensitivity analysis is not required to <br /> comply with the DRMS rules, AFS proposes to focus only on the slope stability analysis results <br /> based on actual rock properties to show that the DRMS required Factor of Safety of 1.15 is met. <br /> The sensitivity analysis evaluated potential Factors of Safety that may result from encountering a <br /> material of lower quality (hypothetical data) than the rock properties used for the slope stability <br /> analysis (actual data). Because the Factors of Safety for these hypothetical sensitivity analysis <br /> conditions are lower than the DRMS requirement, slope stability will be reanalyzed if rock with <br /> lower strength quality of 10 to 20 feet or more in thickness is encountered during mining, thus <br /> requiring a change in geometry to address this lower quality rock and continue to meet the <br /> required Factors of Safety. <br /> If you have any questions, please contact me at 303-913-6583. <br /> Sincerely, <br /> Joel Bolduc <br /> Land and Environment Manager <br /> Encl: <br /> Attachment 1 —Sensitivity Analysis Parameters, Variables, and Results <br /> Attachment 2—Geotechnical Stability Exhibit page 31 of 35 (revised 9/30/2021) <br /> Attachment 3 —Geotechnical Stability Exhibit Appendix I page 4 of 8 (revised 9/30/2021) <br /> Attachment 4—Exhibit R Receipt of Proof of Filing(revised 9/30/2021) <br /> Page 3 of 3 <br />