7010 COLBY AVE 2023-06-01 - Laserfiche WebLink

Mr. Paul Korenovsky ES-6067 June 20, 2018 Page 8 A capillary break, consisting of a minimum of four inches of free-draining crushed rock or gravel, should be placed below the slabs. The free-draining material should have a fines content of 5 percent or less (where the fines content is defined as the percent passing the Number 200 sieve, based on the minus three-quarter-inch fraction). In areas where slab moisture is undesirable, installation of vapor barriers below the slabs should be considered. If a vapor barrier is to be used, it should be a material specifically designed for use as a vapor barrier and should be installed in accordance with the specifications of the manufacturer. Retaining Walls Retaining walls must be designed to resist earth pressures and applicable surcharge loads. The following parameters may be used for design: • Active earth pressure (yielding condition) 35 pcf(equivalent fluid) • At-rest earth pressure (restrained condition) 55 pcf • Traffic surcharge* (passenger vehicles) 70 psf(rectangular distribution) • Passive earth pressure 300 pcf (equivalent fluid) • Coefficient of friction 0.40 • Seismic surcharge 6H psf** * Where applicable ** Where H equals the retained height(in feet) The above design parameters are based on a level backfill condition and level grade at the wall toe. Revised design values will be necessary if sloping grades are to be used above or below retaining walls. Additional surcharge loading from adjacent foundations, sloped backfill, or other loads should be included in the retaining wall design, where applicable. Retaining walls should be backfilled with free-draining material or suitable sheet drainage that extends along the height of the wall and a distance of at least 18 inches behind the wall. The upper 12 inches of the wall backfill can consist of a less permeable soil, if desired. A perforated drainpipe should be placed along the base of the wall and connected to an approved discharge location. A typical retaining wall drainage detail is provided on Plate 3. If drainage is not provided, hydrostatic pressures should be included in the wall design. Earth Solutions NW,LLC