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1 <br />1 <br />1 <br />1 <br />1 <br />1 <br />1 <br />1 <br />1 <br />1 <br />1 <br />1 <br />1 <br />1 <br />1 <br />1-1 <br />1 <br />PENSKE TRUCK LEASING EVERETT ONSITE IMPROVEMENTS <br />CONSTRUCTION STORMWATER POLLUTION PREVENTION PLAN <br />Sitts & Hill Engineers, Inc. <br />Job Number 17,710 <br />BMP C107: Construction Road/Parking Area Stabilization <br />Purpose <br />Stabilizing subdivision roads, parking areas, and other on -site vehicle transportation <br />routes immediately after grading reduces erosion caused by construction traffic or runoff. <br />Conditions of Use <br />Roads or parking areas shall be stabilized wherever they are constructed, whether per- <br />manent or temporary, for use by construction traffic. <br />. High Visibility Fencing (see BMP C103: High Visibility Fence (p.269)) shall be <br />installed, if necessary, to limit the access of vehicles to only those roads and park- <br />ing areas that are stabilized. <br />Design and Installation Specifications <br />. On areas that will receive asphalt as part of the project, install the first lift as soon <br />as possible. <br />. A 6-inch depth of 2- to 4-inch crushed rock, gravel base, or crushed surfacing base <br />course shall be applied immediately after grading or utility installation. A 4-inch <br />course of asphalt treated base (ATB) may also be used, or the road/parking area <br />may be paved. It may also be possible to use cement or calcium chloride for soil <br />stabilization. If cement or cement kiln dust is used for roadbase stabilization, pH <br />monitoring and BMPs (BMP C252: High pH Neutralization Using CO2 (p.409) and <br />BMP C253: pH Control for High pH Water (p.412)) are necessary to evaluate and <br />minimize the effects on stormwater. If the area will not be used for permanent <br />roads, parking areas, or structures, a 6-inch depth of hog fuel may also be used, <br />but this is likely to require more maintenance. Whenever possible, construction <br />roads and parking areas shall be placed on a firm, compacted subgrade. <br />. Temporary road gradients shall not exceed 15 percent Roadways shall be care- <br />fully graded to drain. Drainage ditches shall be provided on each side of the road- <br />way in the case of a crowned section, or on one side in the case of a super - <br />elevated section. Drainage ditches shall be directed to a sediment control BMP. <br />. Rather than relying on ditches, it may also be possible to grade the road so that run- <br />off sheet -flows into a heavily vegetated area with a well -developed topsoil. Land- <br />scaped areas are not adequate. If this area has at least 50 feet of vegetation that <br />water can flow through, then it is generally preferable to use the vegetation to treat <br />runoff, rather than a sediment pond or trap. The 50 feet shall not include wetlands <br />or their buffers. If runoff is allowed to sheetflow through adjacent vegetated areas, it <br />is vital to design the roadways and parking areas so that no concentrated runoff is <br />created. <br />2014 Stonriwater Management Manual for Westem Washington <br />Volume 11 - Chapter 4 - Page 277 <br />SITTS & HILL ENGINEERS, INC. 27 <br />TACOMA, WASHINGTON <br />