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BMP C107: Construction Road/Parking Area Stabilization <br /> Purpose Stabilizing subdivision roads, parking areas, and other onsite vehicle <br /> transportation routes immediately after grading reduces erosion caused by <br /> construction traffic or runoff. <br /> Conditions of Use • Roads or parking areas shall be stabilized wherever they are constructed, <br /> whether permanent or temporary, for use by construction traffic. <br /> • Fencing (see BMPs C103 and C104) shall be installed, if necessary,to <br /> limit the access of vehicles to only those roads and parking areas that <br /> are stabilized. <br /> Design and • On areas that will receive asphalt as part of the project, install the first <br /> Installation lift as soon as possible. <br /> Specifications . A 6-inch depth of 2-to 4-inch crushed rock, gravel base, or crushed <br /> surfacing base course shall be applied immediately after grading or <br /> utility installation. A 4-inch course of asphalt treated base (ATB) may <br /> also be used, or the road/parking area may be paved. It may also be <br /> possible to use cement or calcium chloride for soil stabilization. If <br /> cement or cement kiln dust is used for roadbase stabilization,pH <br /> monitoring and BMPs are necessary to evaluate and minimize the <br /> effects on stormwater. If the area will not be used for permanent roads, <br /> parking areas, or structures, a 6-inch depth of hog fuel may also be <br /> used, but this is likely to require more maintenance. Whenever <br /> possible, construction roads and parking areas shall be placed on a firm, <br /> compacted subgrade. <br /> • Temporary road gradients shall not exceed 15 percent. Roadways shall <br /> be carefully graded to drain. Drainage ditches shall be provided on each <br /> side of the roadway in the case of a crowned section, or on one side in the <br /> case of a super-elevated section. Drainage ditches shall be directed to a <br /> sediment control BMP. <br /> • Rather than relying on ditches, it may also be possible to grade the road <br /> so that runoff sheet-flows into a heavily vegetated area with a well- <br /> developed topsoil. Landscaped areas are not adequate. If this area has at <br /> least 50 feet of vegetation,then it is generally preferable to use the <br /> vegetation to treat runoff, rather than a sediment pond or trap. The 50 <br /> feet shall not include wetlands. If runoff is allowed to sheetflow through <br /> adjacent vegetated areas, it is vital to design the roadways and parking <br /> areas so that no concentrated runoff is created. <br /> • Storm drain inlets shall be protected to prevent sediment-laden water <br /> entering the storm drain system (see BMP C220). <br /> Maintenance • Inspect stabilized areas regularly, especially after large storm events. <br /> Standards • Crushed rock, gravel base, hog fuel, etc. shall be added as required to <br /> maintain a stable driving surface and to stabilize any areas that have <br /> eroded. <br /> • Following construction,these areas shall be restored to pre-construction <br /> condition or better to prevent future erosion. <br /> 4-12 Volume ll—Construction Stormwater Pollution Prevention February 2005 <br />