1710 W MARINE VIEW DR 2024-01-03

BMP C107: Construction Road / Parking Area Stabilization Purpose Stabilizing roads, parking areas, and other on -site vehicle transportation routes immediately after grading reduces erosion caused by construction traffic or stormwater runoff. Conditions of Use Roads and parking areas shall be stabilized wherever they are constructed, whether permanent or temporary, for use by construction traffic. BMP C 103: High -Visibility Fence shall be installed, if necessary, to limit the access of vehicles to only those roads and parking areas that are stabilized. Design and Installation Specifications . On areas that will receive asphalt as part of the project, install the first lift as soon as possible. . A 6-inch depth of 2- to 4-inch crushed rock, gravel base, or crushed surfacing base course shall be applied immediately after grading or utility installation. A 4-inch course of asphalt treated base (ATB) may also be used, or the road/parking area may be paved. It may also be possible to use cement or calcium chloride for soil stabilization. If cement or cement kiln dust is used for roadbase stabilization, pH monitoring and BMP C252: Treating and Disposing of H igh pH Water is necessary to evaluate and minimize the effects on stormwater. If the area will not be used for permanent roads, parking areas, or structures, a 6-inch depth of hog fuel may also be used, but this is likely to require more maintenance. Whenever possible, con- struction roads and parking areas shall be placed on a firm, compacted subgrade. . Temporary road gradients shall not exceed 15 percent. Roadways shall be carefully graded to drain. Drainage ditches shall be provided on each side of the roadway in the case of a crowned section, or on one side in the case of a super -elevated section. Drainage ditches shall be directed to a sediment control BMP. . Rather than relying on ditches, it may also be possible to grade the road so that runoff sheet - flows into a heavily vegetated area with a well -developed topsoil. Landscaped areas are not adequate. If this area has at least 50 feet of vegetation that water can flow through, then it is generally preferable to use the vegetation to treat runoff, rather than a sediment pond or trap. The 50 feet shall not include wetlands or their buffers. If runoff is allowed to sheetflow through adjacent vegetated areas, it is vital to design the roadways and parking areas so that no con- centrated runoff is created. . Storm drain inlets shall be protected to prevent sediment -laden water entering the drainage system (see BMP C220: Inlet Protection). Maintenance Standards Inspect stabilized areas regularly, especially after large storm events. 2019 Stormwater Management Manual for Western Washington Volume /l - Chapter 3 - Page 283