3800 RIVERFRONT BLVD 2025-07-23 - Laserfiche WebLink

f� 1 f] 1 1 1 1 1 f] 1 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 Western Washington Volume 11 - Chapter 4 - Page 375