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By ATL Date 10/11/2020 Client Aggregate Industries Sheet 7 of 7 <br /> Updated Rockfall Evaluation—Lyons Quarry.Technical Review <br /> Chkd.By NA Date 1012112020 Description Update Job# 10246984-002 <br /> 5.0 CONCLUSIONS: <br /> According to the results of the rockfall evaluation described herein, the proposed berm across the <br /> opening at the base of the northeast quarry highwall along with the natural topography will create a <br /> catchment basin that will be adequate with a factor of safety to catch dacite and sandstone rocks <br /> falling from the northeast-facing highwall. The factor of safety could be increased by filling the <br /> catchment area with water and maintaining a pond at the base of the highwall or placing a layer of <br /> loose sand or pea gravel at the base of the highwall to reduce the rockfall energy. The evaluation of <br /> the northwest-facing wall shows a 30 foot runout area and an 8 foot high berm are necessary to catch <br /> 100% of rockfall. A factor of safety of 1.5 added to the berm height results in a 12 foot high berm with <br /> 1 H:1 V side slopes to catch all rockfall from the northwest facing dacite slope. <br /> 6.0 REFERENCES: <br /> Jones, C.L., Higgins, J.D., and Andrew, R.D., 2000, Colorado Rockfall Simulation Program (CRSP), <br /> Version 4.0, Colorado Department of Transportation, Colorado Geological Survey, Colorado School of <br /> Mines, March <br /> Kleinfelder West, Inc., 2008, Summary Report of Engineering Stability Analysis, Lyons Quarry, <br /> Boulder County Colorado, Submitted to Aggregate Industries, February 13th <br />