1515 132ND ST SE 2022-01-20 - 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 II-4.2.4 Contributing Drain- age Area for Vegetated Strips (p.375)): Table 11-4.2.4 Contributing Drainage Area for Vegetated Strips Average Contributing Area Slope Average Contributing Area Percent Slope Max Contributing area Flowpath Length 1.5H : 1 V or flatter 67% or flatter 100 feet 2H :1 V or flatter 50% or flatter 115 feet 4H : 1 V or flatter 25% or flatter 150 feet 6H : 1 V or flatter 16.7% or flatter 200 feet 1 OH : 1 V or flatter 10% or flatter 250 feet 2014 Stormwater Management Manual for Westem Washington Volume 11 - Chapter 4 - Page 375