2122 106TH ST SW 2025-03-12 - Laserfiche WebLink

BMP C232: Gravel Filter Berm Purpose A gravel filter berm is constructed on rights -of -way or traffic areas within a construction site to retain sediment by using a filter berm of gravel or crushed rock. Conditions of Use Where a temporary measure is needed to retain sediment from rights -of - way or in traffic areas on construction sites. Design and • Berm material shall be 1/4 to 3 inches in size, washed well -grade gravel Installation or crushed rock with less than 5 percent fines. Specifications Spacing of berms: — Every 300 feet on slopes less than 5 percent - Every 200 feet on slopes between 5 percent and 10 percent — Every 100 feet on slopes greater than 10 percent • Berm dimensions: — 1 foot high with 3H:1 V side slopes — 8 linear feet per 1 cfs runoff based on the 10-year, 24-hour design storm Maintenance • Regular inspection is required. Sediment shall be removed and filter Standards material replaced as needed. BMP C233: Silt Fence Purpose Use of a silt fence reduces 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. See Figure 4.2.12 for details on silt fence construction. Conditions of Use Silt fence may be used downslope of all disturbed areas. • Silt fence shall prevent soil carried by runoff water from going beneath, through, or over the top of the silt fence, but shall allow the water to pass through the fence. • Silt fence is not intended to treat concentrated flows, nor is it intended to treat substantial amounts of overland flow. Convey any concentrated flows through the drainage system to a sediment pond. • Do not construct silt fences in streams or use in V-shaped ditches. Silt fences do not provide an adequate method of silt control for anything deeper than sheet or overland flow. Volume H— Construction Stormwater Pollution Prevention - December 2014 4-89