9908 18TH AVE W 2024-12-03 - Laserfiche WebLink

Pacific Ridge — DRH, LLC ES-7852.01 March 15, 2022 Page 5 Site Preparation and Earthwork Site preparation activities should consist of installing temporary erosion control measures and performing site stripping within the designated clearing limits. Subsequent earthwork activities will involve mass grading and infrastructure and utility installations. Temporary Erosion Control The following temporary erosion control measures should be considered: • Temporary construction entrances and drive lanes, consisting of at least six inches of quarry spalls, should be considered to both minimize off-site soil tracking and provide stable surfaces at site entrances. Placing geotextile fabric underneath the quarry spalls will provide greater stability if needed. • Silt fencing should be placed around the appropriate portions of the site perimeter. • When not in use, soil stockpiles should be covered or otherwise protected to reduce the potential for soil erosion, especially during periods of wet weather. • Temporary measures for controlling surface water runoff, such as interceptor trenches, sumps, or interceptor swales, should be installed prior to beginning earthwork activities. • Dry soils disturbed during construction should be wetted to minimize dust and airborne soil erosion. • When appropriate, permanent planting or hydroseeding will help to stabilize site soils. Additional Best Management Practices, as specified by the project civil engineer and indicated on the plans, should be incorporated into construction activities. Temporary erosion control measures may be modified during construction as site conditions require, as approved by the site erosion control lead. Stripping Topsoil thickness was variable and extended to depths of about 4 to 28 inches, and root intrusions generally extended below the topsoil into the upper weathered soil. The organic-rich topsoil should be stripped and segregated into a stockpile for later use on site or to haul off site. The native soil remaining immediately below the topsoil may have some root zones and will likely be variable in composition, density, and/or moisture content. The native soil exposed after initial topsoil stripping will likely not be suitable for direct structural support as is and will likely need to either be compacted in place or stripped and stockpiled for reuse as fill; depending on the time of year stripping occurs, the native soil exposed below the topsoil may be too wet to compact and may need to be aerated or treated. The existing fill will need to be removed and replaced as part of initial stripping/mass grading activities. ESNW should observe initial stripping activities to provide recommendations regarding stripping depths and soil suitability. Earth Solutions NW, LLC