C-11. Treatment Swale Design Objective Swales remove pollutants from stormwater by biofiltration, settling, and infiltration. Grassed swales filter pollutants as stormwater runoff moves through the leaves and roots of the grass. By reducing flow velocities and increasing a site’s time of concentration, grassed swales contribute to reducing runoff peaks. Grassed swales that are designed with check dams or incorporate depression storage promote infiltration and can help contribute to satisfying a site runoff capture/storage requirement. Vegetated conveyances designed primarily to convey stormwater from a project rather than to remove pollutants are not subject to this Rule, but instead shall meet the minimum requirements of Rule .1003(2)(c).
