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9. Limitations <br /> This Stability Exhibit was prepared for the exclusive use of Al for the permitting of the <br /> revised highwall configurations within the Morrison Quarry South and West Quarries <br /> through the Colorado DRMS. Our analyses and recommendations may require modification <br /> if there are any changes in the nature, composition, structural characteristics, etc. of the base <br /> rock material within the highwalls exposed by mining within the South Quarry. <br /> The recommendations in this report are based in part on the data obtained from rock core <br /> borings conducted by multiple parties over the entire development phase of the South <br /> Quarry. Subsurface conditions between exploration locations may differ significantly from <br /> those encountered. Additionally, GEI Annual Report mapping data from 2014 through 2019 <br /> was utilized. This data, while developed to be as accurate and representative as possible, was <br /> obtained from a"safe distance" from the active highwall (-30 to 50 feet) to ensure field staff <br /> safety and was not obtained from final highwall locations, but rather active mining fronts. <br /> Significantly differing subsurface conditions could affect the results of our analyses and the <br /> recommendations presented herein. If variations from the anticipated conditions are <br /> encountered, it may be necessary to revise the recommendations in this Exhibit. It is <br /> important to re-evaluate modes of failure potential with relevant geological characteristics <br /> such as discontinuities (spacing, continuity, shear strength); bench orientations relative to the <br /> highwall face; and bench properties that contribute to rock mass behavior as new geological <br /> information becomes available. Therefore, we recommend that GEI be engaged to make site <br /> visits during all phases of mining activity construction to: a) check that the subsurface <br /> conditions exposed during mining are in general conformance with our design assumptions, <br /> and b) ascertain that, in general, the geotechnical aspects of the work are being performed in <br /> compliance with this Exhibit. <br /> Our professional services for this project have been performed in accordance with generally <br /> accepted engineering practices; no warranty, express or implied, is made. <br /> 45 <br /> Aggregate Industries—Morrison Quarry GEI Consultants, Inc. <br /> AM-07 Geotechnical Stability Exhibit November 2020 <br />