Laserfiche WebLink
Pacific Ridge — DRH, LLC ES-7829.01 <br /> August 26, 2021 Page 10 <br /> Provided the structures will be supported as described above, the following parameters may be <br /> used for design of the new foundations: <br /> • Allowable soil bearing capacity 2,500 psf <br /> • Passive earth pressure 300 pcf <br /> • Coefficient of friction 0.40 <br /> A one-third increase in the allowable soil bearing capacity can be assumed for short-term wind <br /> and seismic loading conditions. The passive earth pressure and coefficient of friction values <br /> include a safety factor of 1.5. With structural loading as expected, total settlement in the range of <br /> one inch is anticipated, with differential settlement of about one-half inch. The majority of the <br /> settlement should occur during construction as dead loads are applied. <br /> Retaining Walls <br /> Retaining walls must be designed to resist earth pressures and applicable surcharge loads. The <br /> following parameters may be used for retaining wall design: <br /> • Active earth pressure (unrestrained condition) 35 pcf <br /> • At-rest earth pressure (restrained condition) 55 pcf <br /> • Traffic surcharge (passenger vehicles) 70 psf (rectangular distribution) <br /> • Passive earth pressure 300 pcf <br /> • Coefficient of friction 0.40 <br /> • Seismic surcharge 8H psf* <br /> * Where H equals the retained height(in feet) <br /> The passive earth pressure and coefficient of friction values include a safety factor of 1 .5. <br /> Additional surcharge loading from adjacent foundations, sloped backfill, or other loads should be <br /> included in the retaining wall design. <br /> Retaining walls should be backfilled with free-draining material that extends along the height of <br /> the wall and a distance of at least 18 inches behind the wall. The upper 12 inches of the wall <br /> backfill may consist of a less permeable soil, if desired. <br /> Drainage should be provided behind retaining walls such that hydrostatic pressures do not <br /> develop. If drainage is not provided, hydrostatic pressures should be included in the wall design. <br /> A perforated drainpipe should be placed along the base of the wall and connected to an approved <br /> discharge location. A typical retaining wall drainage detail is provided on Plate 3. <br /> Earth Solutions NW, LLC <br />