Case Studies

Effectiveness of Best Management Practices for Stormwater Treatment as a Function of Runoff Volume


Best management practices (BMPs) such as bioretentions, dry and wet ponds, porous pavement, and many other methods are widely used to reduce the runoff volume and the concentration of sediments and nutrients in the runoff. Numerical models are used to develop and assess water quality management plans that, among others, include BMPs. Those models need to take into account the BMP effectiveness to remove pollutants, being a function of the volume of daily runoff, in order to estimate their performance under a range of different climate scenarios. Circumventing the lack of monitoring data, this study used the Environmental Protection Agency’s system for urban stormwater treatment and analysis integration model (SUSTAIN) to run 22 years (1984–2005) of runoff data from the Patuxent River (Maryland) through seven types of BMPs. It was found that BMP effectiveness decreases sooner, steeper, and deeper with increasing sizes of storm events than assumed in the Chesapeake Bay Phase 5 watershed model. At a minimum, the resulting performance curves should differentiate among BMPs.