1.37 BMP C232 - Gravel Filter Berm
A gravel filter berm retains sediment by filtering runoff through a berm of gravel or crushed rock.
Use a gravel filter berm where a temporary measure is needed to retain sediment from construction sites.
Do not place gravel filter berms in traffic areas; gravel filter berms are not intended to be driven over.
Place gravel filter berms perpendicular to the flow of runoff, such that the runoff will filter through the berm prior to leaving the site.
1.37.3 Design and Installation Specifications
Berm material shall be ¾ to 3 inches in size, washed well-graded gravel or crushed rock, with less than 5 percent fines. Do not use crushed concrete.
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
1 foot high with 3H:1V side slopes
8 linear feet per 1 cubic foot per second runoff based on the 10-year, 24-hour design storm event assuming a Type 1A rainfall distribution (3.0-inches) using a 10-minute timestep.
Regular inspection is required. Sediment shall be removed and filter material replaced as needed.