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1 NM <br /> SARE, INC. <br /> Ceatecbakal Engineers&Construction Materials Con.sullunp <br /> MEMORANDUM <br /> Project Name: Aggregate Industries Haul Road / <br /> Project No. 20.075 <br /> From: Jonathan A. Crystal, P.E. <br /> Date: May 14, 2020 U <br /> Subject: Slope Stability of Haul Road Embankment Slopes <br /> J&T Consulting, Inc. (J&T) requested Cesare,Inc. (Cesare) perform slope stability analyses on various <br /> 1 sections of a proposed haul road for Aggregate Industries (AI). The haul road design includes a 75 <br /> foot total road width, with safety berms along both road edges, over the length of the road and a <br /> remaining travel width of about 43 feet. The design safety berm is 1 to 1, horizontal to vertical (1H <br /> to 1V) side slopes with a height of 8 feet. The original haul road embankment was designed using <br /> 1H to 1V fill slopes with embankment slope heights extending in excess of 120 feet. <br /> The embankment will be constructed predominantly of waste material from the construction <br /> aggregate quarry. Gradation and moisture/density relationship (proctor) test results for this material <br /> are attached. The gradation result indicates the proposed fill ranged from a maximum size particle <br /> of 6 inches to 13% passing the No. 200 screen, estimated as poorly graded and classified as silty <br /> gravel with sand. Cesare initially estimated the strength parameters of this material as follows: <br /> Angle of Internal Friction Cohesion Unit Weight <br /> Parameter M (C) ( ) <br /> Value 40 degrees 50 psf 135 pcf <br /> Cesare performed slope stability analyses using SLOPE/W software published by GeoSlope <br /> International and contained in the GeoStudio 2018 suite of applications (Version 18112). J&T provided <br /> sections through the embankment at approximate maximum embankment height locations within <br /> three road reaches. The section configurations included original ground surface and proposed fill <br /> surface. Surface loading included safety berms and stationary truck wheel loads adjacent to the <br /> safety berm inside toe. Initially,analysis included evaluating remedial techniques for the embankment <br /> should they not exhibit factors of safety (FS) of at least 1.2. The remedial alternatives included toe <br /> berms and Flattening the slopes. <br /> Cesare was provided Colorado Division of Reclamation, Mining, and Safety (DRMS) guidelines, <br /> indicating the following FSs. DRMS considers the haul road a critical structure due to the potential <br /> 1 loss of life on slope failure. Based on communications between various parties participating in this <br /> project, Cesare understands DRMS may not require an FS of 1.5 for the assumed strength condition. <br /> Corporate Office: 7108 South Alton Way,Building B Centennial,CO 80112 <br /> Locations:Centennial Frederick Silverthorne Salida/Crested Butte <br /> Phone 303-220-0300 www.cesareinc.com <br />