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→Berms
===Berms===
===Berms===
*When designed as a stand alone water quality BMP (i.e., not pretreatment to another BMP) the vegetated filter strip should be designed with a pervious berm at the toe of the slope for shallow ponding of runoff.
*When designed as a stand alone water quality BMP (i.e., not pretreatment to another BMP) the vegetated filter strip should be designed with a pervious berm at the toe of the slope for shallow ponding of runoff.
*Media for the berm should consist of 40% excavated [[topsoil]], 40% [[sand]], and 20% [[fine gravel|choking layer]].
*Media for the berm should consist of 40% excavated [[topsoil]], 40% [[sand]], and 20% [[choking layer|fine gravel]].
*The berm should be 150 to 300 mm in height above the bottom of the depression and should contain a perforated pipe [[underdrain]] connected to the storm sewer,
*The berm should be 150 to 300 mm in height above the bottom of the depression and should contain a perforated pipe [[underdrain]] connected to the storm sewer,
*Runoff ponds behind the berm and gradually flows through it, into the underdrain connected to the storm sewer system. The volume ponded behind the berm should be equal to the water quality storage requirement. During larger storms, runoff will overtop the berm and flow directly into a storm sewer inlet. <ref>Cappiella, K., T. Schueler, and T. Wright. 2006. Urban Watershed Forestry Manual, Part 2. Conserving and Planting Trees at Development Sites. Center for Watershed Protection. Prepared for United States Department of Agriculture, Forest Service.</ref>.
*Runoff ponds behind the berm and gradually flows through it, into the underdrain connected to the storm sewer system. The volume ponded behind the berm should be equal to the water quality storage requirement. During larger storms, runoff will overtop the berm and flow directly into a storm sewer inlet. <ref>Cappiella, K., T. Schueler, and T. Wright. 2006. Urban Watershed Forestry Manual, Part 2. Conserving and Planting Trees at Development Sites. Center for Watershed Protection. Prepared for United States Department of Agriculture, Forest Service.</ref>.