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...were modeled to determine the resisting force required to reach a factor of safety of 1.5." The <br /> West section resultant FOS is 1.45 and resultant FOS for the East section for <br /> are 1.4 and 1.41 respectively as provided in Appendix G. In order to ensure the minimum criteria <br /> of the Division's Section 30 is met,please have KUE provide updated mechanical stabilization <br /> recommendations and associated analyses that meets or exceeds the minimum FOS requirements <br /> of 1.5 for static conditions. <br /> KUE:Stability models in Appendix G have been revised to achieve a FOS of 1.5 static and 1.3 <br /> seismic. <br /> Division: During the Division's review of the applied seismic coefficient, it was observed that <br /> the value was not provided within discussion of the Report.Additionally it was unclear as to what <br /> methodology was used in determining the applied seismic coefficient. Please have KUE provide <br /> additional clarification within Section 7 regarding the design seismic coefficient value used along <br /> with the methodology and rational. <br /> KUE:Further discussion of reasoning and how the seismic design coefficient was selected has <br /> been included in section 7. <br /> After reviewing KUE's updated Section 7 of the Report,KUE has provided additional rational regarding <br /> the applied seismic design coefficient. KUE states in the Report that due to the similarities between soil <br /> nail design and rock dowel design,the seismic design methodology from FHWA GEC 7 was utilized <br /> which was developed following AASHTO LRFD Bridge Design Specifications. Both methodologies and <br /> design references are published and widely accepted engineering methodology. Additionally,as noted in <br /> the Division's February 6,2024 memo,the Division was able to corroborate the peak gravitational <br /> acceleration, site adjustment factors and resulting seismic coefficient provided under Appendices D and G <br /> with published information from the applicable USGS Seismic Design Map Web Services. With the <br /> additional provided rational and discussion,the Division has no additional comments and this item has <br /> been satisfied. <br /> Division's Comments and/or Questions <br /> Based on the updated and provided Report conducted by KUE for the Mine,all remaining adequacy items <br /> from the Division's February 6,2024 memo have been satisfied and I have no further comments. <br /> This concludes my review of the provided geotechnical report, "Rock Failure Analysis and Stability", <br /> conducted by Kilduff Underground Engineering, Inc. on behalf of RMR Aggregates, Inc. regarding the <br /> rock failure event that occurred on January 18,2023 at the Mid Continent Limestone Quarry(Mine). If <br /> you have any questions feel free to contact me. <br /> Sincerely, <br /> Zach Trujillo <br /> Environmental Protection Specialist <br /> (303) 866-3567 ext. 8164 <br /> Zach.Trujillo@state.co.us <br /> Mid Continent Limestone Quarry Geotechnical Review Memo March 25,2024 <br />