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Morrison Quarry AM-07 Geotechnical Stability Exhibit <br /> DRMS Permit M-1973-021 <br /> Aggregate Industries WCR Inc. <br /> Global Failures <br /> The global stability evaluation includes highwall slopes as high as 1,400 feet, which is the anticipated <br /> final mining depth. The Hoek-Brown method is also used to develop strength parameters for the slope <br /> stability evaluation. The global failure case uses the same input for the intact rock and the rock mass <br /> but does not include a disturbance factor. The input parameters for global failures are summarized <br /> below. <br /> Parameter Description Selected Basis <br /> Value <br /> UCS (oci) Uniaxial compressive strength of 12.5 ksi Avg. value of 7 UCS tests <br /> intact specimen from lab testing performed in 2018 <br /> Geologic Strength Quantified value of rock mass 40 Based on blocky, disturbed <br /> Index (GSI) based on visual assessment of rockmass with Fair to Good <br /> structure and the condition of discontinuity surfaces <br /> discontinuities <br /> Material Constant Based on rock type 28 Recommended value from Roc <br /> (m;) Lab for gneiss bedrock (28±5) <br /> Disturbance Accounts for disturbance due to 0 Failure plane is deep within <br /> Factor(D) blasting highwall and likely not disturbed. <br /> Modulus Ratio Based on rock type 500 Recommended value from <br /> (MR) RocLab for gneiss bedrock <br /> (500±225) <br /> Hoek Brown Criterion-Global Failures <br /> m b 3.28494 <br /> s 0.00127263 <br /> a 0.511368 <br /> Global Failure Envelope <br /> 2.5 <br /> 2Approx.Max.Mine Depth 1400ft <br /> Y <br /> 1.5 <br /> C1 <br /> N <br /> L 1 <br /> N <br /> —Hoek-Brown Criterion <br /> 0.5 <br /> 0 <br /> 0 0.5 1 1.5 2 <br /> Normal stress(ksi) <br /> GEI Consultants, Inc. 6 of 25 Appendix C.1 <br /> November 2020 <br />