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BRIERLEY <br /> ASSOCIATES <br /> Creating Space Underground <br /> February 10, 2015 <br /> File No.: 514104-000 <br /> Asphalt Paving Co. <br /> 14802 W 44th Ave <br /> Golden, CO 80403 <br /> Attention: M.L. Richardson <br /> Director of Strategy and Sustainable Development <br /> Subject: Summary of Material properties for Rock Mass and Joints <br /> Ralston Quarry <br /> Golden, Colorado <br /> Ladies and Gentlemen: <br /> Brierley Associates (Brierley) is providing this letter to summarize the material properties used <br /> for the rock mass and its joints during the evaluation of rock slope stability provided in our letter <br /> dated July 22, 2014 for Asphalt Paving Co. (APC's) rock quarry located at 6569 Highway 93, <br /> just west of the intersection with West 64th Parkway, in Golden, Colorado. This summary has <br /> been prepared in response to Michael Cunningham's email to Ben Langenfeld dated January <br /> 22, 2015. <br /> Rock Mass and Joint Properties <br /> Values for material properties for the rock mass and its joints were determined based on <br /> laboratory testing, field observations, and back analysis of existing failures observed in the field. <br /> Laboratory testing included direct shear testing on six representative samples selected from the <br /> rock core recovered during the field investigation. Two samples were selected from each rock <br /> type, rim-phase basalt and core-phase basalt, and were tested via direct shear methods along <br /> existing joints. The average results of these tests for each rock type are summarized below as <br /> well as a conservative representative value for an "average" basalt joint that was used during <br /> the analyses. The test results in their entirety are included in Appendix A. <br /> Effective Effective Moist Unit <br /> Material Friction Angle cohesion Weight <br /> �' (degrees) c' (psf) 7. (pcf) <br /> Core Basalt 28 10,000 173 <br /> Joint <br /> Rim Basalt Joint 36 3,000 172 <br /> Average Basalt 33 4,000 177 <br /> Joint <br /> 990 S.Broadway,Ste. 222,Denver,CO 80209 1303.703.1405 1 www.BrierleyAssociates.com <br />