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PROPOSED RETAINING WALL <br />RPEE HAUL ROAD SWITCHBACK <br />WEST ELK MINE <br />GUNNISON COUNTY, STATE OF COLORADO <br />1. General <br />1.1 The retaining wall design presented herein is based on the provided AutoCAD file " RPEE <br />Haul Road 2, Switchback" prepared by Mountain Coal Company, dated June 17, 2013. <br />1.2 Location of the proposed retaining wall shall be based on the wall layout on the provided <br />AutoCAD file. Field adjustments for the wall horizontal layout may be necessary. Any <br />adjustments should be approved by the Project Engineer. These drawings should be <br />reviewed and approved by the Project Civil Engineer, with regards to wall geometry, prior to <br />construction. <br />1.3 Construction of the retaining walls shall be in accordance with the design drawings and the <br />manufacturers construction guidelines. <br />1.4 The Contractor shall verify the location of proposed and existing underground features prior <br />to excavation. <br />1.5 Locations and elevations of precast blocks and drainpipes shall be periodically verified by <br />Owner's surveyor during and at completion of construction. <br />1.6 This set of retaining wall plans is based specifically on the wall to be constructed by a <br />approved wall subcontractor of West Elk Mine, Mountain Coal Company, L L C and <br />constructed with a Redi -Rock wall system. No substitution is allowed <br />1.7 Wall subgrade shall be compacted to a minimum of 98% of the maximum standard Proctor <br />dry density (ASTM D698) at moisture contents from 3 percent below to 1 percent above the <br />optimum moisture content prior to construction of the walls. <br />1.8 Wall backfili shall be compacted to a minimum of 95% of the maximum modified Proctor dry <br />density (ASTM D1557) at moisture contents within 2 percent of the optimum moisture <br />Content <br />1.9 Gravel bac kfill (drains) shall be vibratory compacted. <br />2. Design Criteria <br />2.1 Design parameters used for wall design: <br />Material Type <br />Friction Angle <br />(degree) <br />Cohesion <br />(W <br />Unit Weight <br />(Pcf) <br />Existing Fill <br />Is <br />350 <br />overturnim <br />atrve <br />600 <br />1 <br />mpo <br />Global Stability <br />1.3 <br />2.3 <br />Assumed allowable bearing capacity = 3,000 Pat <br />3 <br />Abbreviations <br />2.2 External Stability <br />Criteria <br />Min. Factor ct Saf <br />Base Sliding <br />1.5 <br />overturnim <br />1.5 <br />Bearina <br />2.0 <br />Global Stability <br />1.3 <br />2.3 <br />Assumed allowable bearing capacity = 3,000 Pat <br />3 <br />Abbreviations <br />BG Finish grade at bottom of wall <br />BIN Bottom of wall at top of leveling pad <br />EQU Equal <br />H Design wall height <br />MAX Maximum <br />MIN Minimum <br />NTS Not to scale <br />RL Reinforcement length <br />STA Station <br />STD Standard <br />TG Finished grade at top of wall <br />TW Top of wall <br />4. <br />Index of Drewinas <br />Figure 1 General Notes <br />Figure 2 Well A Site Plan <br />Figure 3 Wall A Elevation <br />Figure 4 Typical Wall Section <br />Figure 5 Typical Wall Details <br />5 <br />Wall Face Area <br />Well A 1,802 SF <br />