Design Efficiency of Stormwater Detention Basins

In addition to increased flood runoff, urban development has caused a significant increase in sediment loads in streams. While many means of sediment and runoff control have been proposed, stormwater detention has been shown to be one of the more cost efficient means. Because detention facilities have not been used extensively in the past, a data base is not available for determining the effect of design factors on sediment trap efficiency and runoff control characteristics. A mathematical model, which includes erosion, sedimentation, and detention facility components, was developed from principles of hydraulics and classical settling mechanics. The model was used to examine the effect of: (1)Detention basin location; (2)soil particle size distribution; (3)basin depth; (4)initial storage, and (5)orifice diameter. An understanding of the relative importance of these factors may lead to better design of stormwater detention facilities.