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Morrison Quarry AM-07 Geotechnical Stability Exhibit <br /> DRMS Permit M-1973-021 <br /> Aggregate Industries WCR Inc. <br /> in 2017. The sillimanitic gneiss is typically identified by its lighter color and 'oily'texture <br /> in hand specimen. Figure 2 shows the locations of sillimanitic gneiss in the South Quarry <br /> as well as mapped dikes and other structures. Photo 3 shows an outcrop of sillimanitic <br /> gneiss as observed in the South Quarry. <br /> Other geologic units include mafic dikes and granitic pegmatites, which crosscut <br /> foliations within the gneiss units and therefore post-date these formations. A total of 5 <br /> mafic dikes were mapped within the Central, South, and West Quarry areas during <br /> reconnaissance mapping performed by GEI in 2018. Only one mafic dike is mapped in <br /> the South Quarry, and it trends 280-300 degrees with an apparent dip of 55-65 degrees. <br /> The dike is easily visible in several east-facing highwalls and trends towards the gulch <br /> between South Quarry and West Quarry. Photo 4 shows a mafic dike as observed in the <br /> South Quarry and Photo 5 shows a mafic dike in the Central Quarry. <br /> A fault/shear zone has been mapped through the footprint of the south quarry that is <br /> observable in highwall benches around El. 6700 and 6760. Where exposed, the fault <br /> dips approximately 70 degrees to the south. <br /> The bedrock structure within the South Quarry is dominated by an undulating, <br /> subhorizontal foliation. Host rocks are jointed and cut by subvertical dikes with <br /> northwesterly strikes, which are locally folded and faulted. The observed and mapped <br /> faults typically have moderate dips (— 35°)to north and south, striking generally east- <br /> west. Figure 3 contains a stereonet showing measurements from onsite discontinuities, <br /> including foliations and Primary and Secondary joint sets. <br /> Project Data: Bedrock samples collected from the South Quarry have been analyzed for their strength <br /> properties, including the unconfined compressive strength (UCS) and shear strength <br /> parameters. Results of UCS and direct shear testing are contained at the end of this <br /> calculation package. <br /> Approach: The slope stability evaluation includes assessing the potential for localized failures(less <br /> than 250 feet high), and the potential for global failures that encompass the entire rock <br /> slope. Strength parameters are developed for both scenarios using the Hoek-Brown <br /> Method. <br /> GEI Consultants, Inc. 2 of 25 Appendix C.1 <br /> November 2020 <br />