Laserfiche WebLink
a000LORADO <br /> Division of Reclamation, <br /> Mining and Safety <br /> Department of natural Resources <br /> Date: March 25,2024 <br /> To: Amy Yeldell <br /> CC: Russ Means <br /> Travis Marshall <br /> Amy Eschberger <br /> From: Zach Trujillo <br /> RE: Mid Continent Limestone Quarry,DRMS File No.M-1982-121 <br /> Rock Failure Analysis and Stability Report Review <br /> Amy, <br /> As requested I have reviewed the provided geotechnical report,"Rock Failure Analysis and Stability" <br /> (Report),conducted by Kilduff Underground Engineering, Inc. (KUE)on behalf of RMR Aggregates, Inc. <br /> (RMR)regarding the rock failure event that occurred on January 18,2023 at the Mid Continent <br /> Limestone Quarry(Mine). This memo specifically addresses the updates to the Report along with the <br /> response to the Division's memos dated September 29,2023 and February 6,2024 as provided under <br /> Technical Revision No. 6 (TR-6). Discussion chronology regarding adequacy items noted in the <br /> Division's September 29,2023 that were satisfied by KUE have been removed due to redundancy and to <br /> provide clarity on the remaining adequacy items. For more information regarding the Division's previous <br /> reviews of the Report, please refer to the Division's discussed memos from Zach Trujillo to Amy Yeldell. <br /> All remaining items from the Division's February 6,2024 memo along with KUE's responses are <br /> discussed below. Questions and comments regarding the Report to ensure all Rules and requirements are <br /> satisfied will be summarized at the end of this memo. <br /> Division's Comments and/or Questions—February 6,2024 Memo <br /> • Division: Under Section 6 of the Report, a long-term static stability analysis was conducted using <br /> the post-mining configuration of the for varying bench slope geometries. <br /> A total of three bench slope geometries were analyzed with resulting FOS as provided in Table 4 <br /> of the Report. However only the results from the bench slope geometry for 1.67:1 was provided <br /> under Appendix D.Additionally, it appears an error exists in Table 4 for bench slope geometry of <br /> 1.67K-1 V. The resulting slope stability analysis under Appendix D shows a FOS of 1.66 while <br /> Table 4 has a FOS of 1.63. Please have KUE provided a corrected Table 4 (is necessary) and the <br /> slope stability analyses for the other bench slope geometries provided under Table 4. <br /> KUE:SA) Table was misnumbered and has been corrected to Table 6. SB)Appendix D now <br /> includes stability runs for bench geometries of 1:1, 1.4:1 and 1.67:1 for both static and seismic. <br /> SC)Appendix D is correct and the text has been edited. <br /> Mid Contienent Limestone Quarry Geotechnical Review Memo March 25,2024 <br /> 4F COlO <br /> �F <br /> H � <br /> 1313 Sherman Street, Room 215, Denver, CO 80203 P 303.866.3567 F 303.832.8106 http://mining.state.co.us <br /> Jared S. Polis, Governor I Dan Gibbs, Executive Director I Michael Cunningham, Director <br /> �1876� <br />