2020-06-19_REVISION - M1973021 - Laserfiche WebLink

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' 7200 10+50 7200 ' 718o 71ao 7160 DESIGN GRADE 7160 i EL 7156.3 w 7140 7140 UJ LL LL 7120 F 7120 W 7100 7100 UJ EL 7099-58 7080 d'� - EXISTING GROUND 7080 $ - l 7060 7060 EL 7064 53 j 7040 7040 ' 140 120 100 80 60 40 20 0 20 40 60 80 100 120 140 OFFSET-FEET ' Figure 2. Proposed preliminary roadcut geometry. Profile location shown in Figure 1. The current approach is to evaluate the kinematic stability of the road cut using discontinuity data that was collected from previous site studies at the South Quarry and apply this dataset to the proposed rock cut in the West Quarry. The intent of the preliminary analysis is to estimate level ' of relative risk for the rock excavation and to aid in AI's planning for future rock stabilization. The dataset utilized for the preliminary analysis was collected as part of the annual monitoring performed at the nearby South Quarry. The applicability of the dataset relies on the assumption ' that the orientations of major foliations,fractures,and other discontinuities are generally consistent between the South Quarry and the West Quarry. GEI considers this a valid assumption and is appropriate at this stage in the haul road development. As this analysis is preliminary in nature, a more refined kinematic evaluation should be performed during construction using site specific data to evaluate the potential for local kinematic failures and identify discrete locations of concern. Site Location and Description Morrison Quarry is a hard rock quarry,owned and operated by Al, located approximately one-half mile west of Colorado Highway 8 and approximately one-half mile north of U.S. Highway 285 in ' Morrison, Colorado. The mine site is located west of the Dakota hogback along the Front Range west of Denver, Colorado, in Section 10 of Township 5 South, Range 70 West of the 61h Principle Meridian. The Morrison Quarry consists of three cells; the North Quarry, the Central Quarry, and ' the South Quarry. Active mining no longer occurs within the North or Central Quarries. The bedrock at the South Quarry is largely Precambrian fine-to medium-grained granitic or biotite ' gneiss with localized intrusions of granitic pegmatites and mafic dikes. The rock is slightly weathered to moderately weathered, with increased weathering near fractures and discontinuities. It is strongly foliated with foliation spacing that ranges from less than 1-inch to several feet.