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CITY OF EVERETT STORMWATER MANAGEMENT MANUAL <br /> �� 3.2.6 BMP C107: Construction RoadfParking Area Stabilization <br /> Purpose <br /> Stabilizing subdivision roads,parking arcas and other onsite vehidc transportation routes immediately <br /> after grading reduces erosion caused by construction traffic or ruoofi. <br /> Condltions of Use <br /> • Roads or parking areas shall be stabilized wherever they are cnnstructed,whether pertnanent or <br /> temporary, for use by conswction haffia <br /> • Fencing(sce BMP C 103)shall be installed,if nccessary,to limit the access of vehicles to only <br /> those roads and pazking areas that are stabilized. <br /> Design and Installation Specifications <br /> 1. On arcas that w�ll receive asphalt as part of the ptoject,install the first lift as soon as possible. <br /> 2. A 6-inch depth of 2-to 4•inch crushed rock,gravel base, or crushed surfacing base course shall <br /> be applied immediatcly after grading or utility installation. A 4-inch course of asphalt tre2tcd <br /> basc mey also bc used,or the roac�/pazking azea may bc paved. It may also be possible to use <br /> cement or calcium chloride for soil stabilization. If cement or cement kiln dust is used for road <br /> base stabilization,pH monitoring and BMI's are necessary ta evaluate and minimize the effects <br /> on stocmwater. If the area will not be used fot permanent roads,parking arees,or struchues,a <br /> 6-inch depth of hog f�el may also be used,but this is likely lo require more maintenance. <br /> Whenever possible,conshuction roads and perking arcas shell be placed on a firm,compacted <br /> subgrade. <br /> ' 3. Temporary road gradients shall nut exceed l5 percent. Roadways shall be cazefully�aded to <br /> drain. Drainage ditches shall be provided on each sidc of the roadway in the case of a crowned <br /> section,or on one side in the case of a super-elevated sectiou. Drainage ditches shall be directed <br /> to a sediment contro! BMI'. <br /> 4. Rsther.than celying on ditches, it mey also be possible to�ade the road so that runoff sheet-flows <br /> into a 6eavily v^_be:ated area with a well-develaQed topsoil. Landscaped areas are not adequate. <br /> If this area has at least 50 fect of vcgctation,then it is generally prefcrable to use the vegetation to <br /> treat runoff, rather than a sedimcnt pond or trap. The 50 feet shall not ir�clude H�etlands. If runofT <br /> is allowed to shectflow through adjacent vegctated arcas, it isvital to dcsign thc roadways and <br /> parking araas su that no conccntrated tunoff is created ' <br /> 5. Storm drain inlcts shall bc protected to preveot sedimenbladen watcr entering lhe stortnwater <br /> drainage system(see BMP C220). <br /> Maintenance Sfandards <br /> I. Inspect stubilized arcas regularly,especially after large stom�events <br /> 2. Cnished rock,gravel base,hog fuel,etc. shall be added as requircd to maintain a stable driving <br /> surface and to stabilize any areas that havic eroded <br /> 3. Following constmction,thcse arcas shall be restorcd to preconstruction condition or bettcr to <br /> prevent future erosion. <br /> Vofume 11—Constructron Stormwater Pollution Prevention <br /> &8 <br />