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Veritas Construction Inc ES-4011.03 <br /> June 17, 2016 Page 11 <br /> Revised June 22, 2016 <br /> IRetaining Walls <br /> Conventional concrete retaining walls for the project will likely consist of building foundation <br /> I walls and exterior site retaining walls. Retaining walls should be designed to resist earth <br /> pressures and any applicable preload loads. The following values should be used for concrete <br /> retaining and foundation wall design: <br /> I • Active earth pressure (yielding wall 35pcf (equivalent fluid / granular fill) <br /> Y 9 ) ( q <br /> I • At-rest earth pressure (restrained wall) 55 pcf <br /> • Traffic surcharge (passenger vehicles) 70 psf(rectangular distribution) <br /> I • Passive earth pressure 300 pcf (equivalent fluid) <br /> I • Allowable soil bearing capacity 3,000 psf <br /> • Coefficient of friction 0.40 <br /> I • Lateral seismic surcharge* 6H (where H equals wall height in feet) <br /> I *for walls at least six feet in height <br /> Additional surcharge loading from foundations, sloped backfill, or other loading should be <br /> I included in the retaining wall design, where applicable. Drainage should be provided behind <br /> retaining walls such that hydrostatic pressures do not develop. If drainage is not provided, <br /> hydrostatic pressures should be included in the wall design. The geotechnical engineer should <br /> 1 review retaining wall designs to confirm that appropriate earth pressure values have been <br /> incorporated into the design and to provide additional recommendations. <br /> IConcrete retaining walls should be backfilled with free draining material that extends along the <br /> height of the wall, and a distance of at least 18 inches behind the wall. The upper one foot of <br /> the wall backfill can consist of a less permeable soil, if desired. A perforated drain pipe should <br /> be placed along the base of the wall, and connected to an approved discharge location. A <br /> typical retaining wall drainage detail is provided as Plate 3 of this study. <br /> IMechanically Stabilized Earth (MSE) Walls <br /> I MSE walls will likely be utilized throughout the site as part of the overall final grading plan. <br /> Rockeries throughout cut areas of the site may also be utilized. ESNW previously prepared <br /> wall design recommendations and details for the MSE and rockery wall construction. <br /> I <br /> I <br /> IEarth Solutions NW, LLC <br />