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• Remove sediment deposits when the deposit reaches approximately <br />one-third the height of the silt fence, or install a second silt fence. <br />• Replace filter fabric that has deteriorated due to ultraviolet breakdown. <br />BMP C234: Vegetated Strip <br />Purpose Vegetated strips reduce the transport of coarse sediment from a <br />construction site by providing a temporary physical barrier to sediment <br />and reducing the runoff velocities of overland flow. <br />Conditions of Use • Vegetated strips may be used downslope of all disturbed areas. <br />Vegetated strips are not intended to treat concentrated flows, nor are <br />they intended to treat substantial amounts of overland flow. Any <br />concentrated flows must be conveyed through the drainage system to a <br />sediment pond. The only circumstance in which overland flow can be <br />treated solely by a strip, rather than by a sediment pond, is when the <br />following criteria are met (see Table 4.2.4): <br />Table 4.2.4 <br />Contributing Drainage Area for Vegetated Strips <br />Average Contributing <br />area Sloe <br />Average Contributing area <br />Percent Sloe <br />Max Contributing <br />area Flowpath Length <br />1.5H:1 V or flatter <br />67% or flatter <br />100 feet <br />2H:1 V or flatter <br />50% or flatter <br />115 feet <br />4H:1 V or flatter <br />25% or flatter <br />150 feet <br />6H:1 V or flatter <br />16.7% or flatter <br />200 feet <br />1OH: 1 V or flatter 4-10% <br />or flatter <br />250 feet <br />Design and <br />The vegetated strip shall consist of a minimum of a 25-foot flowpath <br />Installation <br />length continuous strip of dense vegetation with topsoil. Grass - <br />Specifications <br />covered, landscaped areas are generally not adequate because the <br />volume of sediment overwhelms the grass. Ideally, vegetated strips <br />shall consist of undisturbed native growth with a well -developed soil <br />that allows for infiltration of runoff. <br />• The slope within the strip shall not exceed 4H:IV. <br />• The uphill boundary of the vegetated strip shall be delineated with <br />clearing limits. <br />Maintenance <br />• Any areas damaged by erosion or construction activity shall be <br />Standards <br />seeded immediately and protected by mulch. <br />• If more than 5 feet of the original vegetated strip width has had <br />vegetation removed or is being eroded, sod must be installed. <br />• If there are indications that concentrated flows are traveling across the <br />buffer, surface water controls must be installed to reduce the flows <br />Volume H— Construction Stormwater Pollution Prevention - December 2014 <br />4-95 <br />