7010 COLBY AVE 2023-06-01 - Laserfiche WebLink

Mr. Paul Korenovsky ES-6067 June 20, 2018 Page 5 Temporary Erosion Control 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 a stable access surface for construction vehicles. Geotextile fabric may be placed below the quarry spalls for greater stability of the temporary construction entrance. Erosion control measures should consist of silt fencing placed around appropriate portions of the site perimeter. Soil stockpiles should be covered or otherwise protected to reduce the potential for soil erosion during periods of wet weather. Temporary approaches for controlling surface water runoff should be established prior to beginning earthwork activities. Additional Best Management Practices (BMPs), as specified by the project civil engineer and indicated on the plans, should be incorporated into construction activities. Stripping Topsoil was encountered within the upper approximately 2 to 12 inches of existing grades at the test pit locations. ESNW should be retained to provide site stripping recommendations at the time of construction. Topsoil and/or organic-rich soil is not considered suitable for use as structural fill. If desired, topsoil and/or organic-rich soil may be used in non-structural areas. Excavations and Slopes Based on the soil conditions observed at the test pit locations, the following allowable temporary slope inclinations, as a function of horizontal to vertical (H:V) inclination, may be used. The applicable Federal Occupation Safety and Health Administration (OSHA) and Washington Industrial Safety and Health Act (WISHA) soil classifications are also provided: • Loose and medium dense soil or fill 1.5H:1 V (Type C) • Areas containing groundwater seepage 1.5H:1 V (Type C) • Medium dense to dense native soil 1 H:1 V (Type B) • Dense to very dense native soil 0.75H:1 V (Type A) Steeper temporary slope inclinations may be feasible depending on exposed soil conditions and a site-specific design by ESNW during construction. Permanent slopes should be planted with vegetation to enhance stability and to minimize erosion and should maintain a gradient of 2H:1 V or flatter. The presence of perched groundwater may cause localized sloughing of temporary slopes due to excess seepage forces. An ESNW representative should observe temporary and permanent slopes to confirm the slope inclinations are suitable for the exposed soil conditions and to provide additional excavation and slope recommendations, as necessary. If the recommended temporary slope inclinations cannot be achieved, temporary shoring may be necessary to support excavations. Earth Solutions NW,LLC