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By ATL Date 10/11/2020 Client Aggregate Industries Sheet 1 of 7 <br /> Updated Rocktall Evaluation—Lyons Quarry:Technical Review <br /> Chkd.By NJL Date 10212020 Descripbon Update Job# 10246984-002 <br /> 1.00BJECTIVE: <br /> The objective of this Updated Rockfall Evaluation of Lyons Quarry is to use the Colorado Rockfall <br /> Simulation Program (CRSP) (Jones et al, 2000) to simulate rocks falling down the dacite highwall, <br /> design appropriate mitigation measures, and evaluate the required size of rockfall catchment areas <br /> and height of catchment berms. <br /> The dacite highwall at Lyons Quarry has two main faces as shown in Figure 1; the northeast(NE) and <br /> northwest(NW)facing highwalls. Section A was selected as the critical slope for the northeast-facing <br /> slope based on highwall height, steepness and lack of benches. This location coincides with Section <br /> D-D' from the 2008 Kleinfelder report(Kleinfelder, 2008). This section was evaluated to find the <br /> necessary runout area to catch 100% of rocks falling from the slope and to evaluate the effect of a <br /> catchment berm at the end of the runout area. Section B was selected as the critical slope for the <br /> northwest-facing wall based on height and steepness and was evaluated to find the necessary height <br /> of a catchment berm to be placed along the northwest side of the bench as shown in Figure 1. <br /> Proposed <br /> Swale Berm <br /> Alternative Catchment <br /> Quarry 1 Rockfalll Berm Alignment <br /> Catchment Basin (18 ft high with 1:1 side slopes) <br /> Access Restriction <br /> Fencing <br /> Catchment Berm �\ <br /> Alignment Quarry 1 / <br /> (12 feet high with 1:1 <br /> side slopes) <br /> B <br /> NW Dacite A <br /> Wall NE Dacite <br /> Wall <br /> Quarry 2 <br /> (to be backtilled) j <br /> Dacite/Sandstone <br /> Contact <br /> / (2:1 grading above thi11ine) <br /> Figure 1. Plan view of Lyons Quarry showing dacite walls and proposed rockfall mitigation <br />