3535 RIVERFRONT BLVD 2023-02-21 - Laserfiche WebLink

Maintenance Standards . Repair any damage immediately. . Intercept and convey all evident concentrated flows uphill of the silt fence to a sed- iment pond. . Check the uphill side of the fence for signs of the fence clogging and acting as a barrier to flow and then causing channelization of flows parallel to the fence. If this occurs, replace the fence or remove the trapped sediment. . Remove sediment deposits when the deposit reaches approximately one-third the height of the silt fence, or install a second silt fence. . Replace filter fabric that has deteriorated due to ultraviolet breakdown. BMP C234: Vegetated Strip Purpose Vegetated strips reduce the transport of coarse sediment from a construction site by providing a temporary physical barrier to sediment and reducing the runoff velocities of overland flow. Conditions of Use . Vegetated strips may be used downslope of all disturbed areas. . Vegetated strips are not intended to treat concentrated flows, nor are they intended to treat substantial amounts of overland flow. Any concentrated flows must be con- veyed through the drainage system to a sediment pond. The only circumstance in which overland flow can be treated solely by a strip, rather than by a sediment pond, is when the following criteria are met (see Table 11-4.2.4 Contributing Drain- age Area for Vegetated Strips (p.375)): Table II-4.2.4 Contributing Drainage Area for Vegetated Strips Average Contributing Average Contributing Area Max Contributing area Area Slope Percent Slope Flowpath Length 1.5H : 1V or flatter 67% or flatter 100 feet 2H : 1V or flatter 50% or flatter 115 feet 4H : 1V or flatter 25% or flatter 150 feet 6H : 1V or flatter 16.7% or flatter 200 feet 10H : 1V or flatter 10% or flatter 250 feet 2014 Stormwater Management Manual for Western Washington Volume ll- Chapter 4 -Page 375