2023-06-28_ENFORCEMENT - M1982121 (2)

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On the East Face, planar, very high persistence, moderately rough to rough, south-dipping bedding planes defined the structure between the two upper limestone beds. Photo 5 in Appendix A shows this structure. The bedding plane dips 30 degrees in a 189-degree azimuth direction. Appendix A photos demonstrate the plane becomes more undulatory and rough with large crystals and second-order asperities traversing from east to west. The mudstone interbed has eroded back from the face of the outcrop face and was difficult to evaluate for strength parameters. The mudstone appears to be well cemented with clasts of limestone entrained. In areas reachable with a geologic pick the mudstone was evaluated as weak(R2). CaCO3 stalactites are forming across the 4 to 7-inch aperture between the upper and lower limestone forming a connection between the two beds. The larger stalactites are forming on the face of the limestone indicating deposition from CaCO3-rich surface runoff. Smaller stalactites were observed within the asperity.The stalactite connections indicate the East Face has not slid on the bedding plane over an extensive period of geologic time. The structure dominating the limestone bed face appears to be comparable to the apparent release plane for the West Face ground event. The secondary joint set dips 45 degrees in a 055- degree azimuth direction. The joint is generally planar, slightly rough, low to medium persistence with moderately close to wide joint spacing.The secondary joint set was observed consistently across the East Face. KINEMATIC ANALYSIS OF FAILURE MODES Kinematic analyses incorporate the discontinuity data collected from the Mid-Continent Limestone Quarry and slope above to help identify potential rock slope failure conditions. Discontinuity data from the field mapping were compiled on stereographic projections (lower hemisphere, equal angle) and analyzed with the computer program DIPS v. 8.021 (RocScience, 2022) to evaluate trends and discontinuity sets. The resulting stereographic plots are included in Appendix C. The purpose of these analyses is to evaluate the potential for shallow failures in the cut slope walls rather than circular failure.The results are used in analyzing the stability and factor of safety for failure modes. Characteristics of individual discontinuities identified on the East Face slope are provided in Appendix B. Global mean planes and rosette plots illustrate the East Face rock mass is controlled primarily by bedding, dipping moderately to the south-southwest, creating dip slopes that dictate slope topography. Nine bedding structure measurements from the CGS throughout the quarry expansion area are presented on Kirkham et al., 2008, ranging from 24 to 44 degrees, all dipping to the south- southwest. The CGS measurements are generally consistent with data collected during the KUE April 2023 field reconnaissance that indicate a tighter cluster of dip ranging from 29 to 32 degrees, all dipping to the south-southwest (192' +/-10).The steeper CGS measurement of 44 degrees is assumed to be lower on the face where the fold is steeper. The primary discontinuities controlling rock mass stability in the slope are generally persistent and control rock mass response. Page.4 535 16th STREET,SUITE 620 1 DENVER,CO 80202 1 (303)732-3692 1 WWW.KILDUFFUNDERGROUND.COM