Modeling BMP and Vegetative Cover Performance for Highway Stormwater Runoff Reduction

Abstract Urbanization generally leads to increases of impervious surfaces, changes of the natural hydrologic conditions and watershed's response to stormwater runoff. The application of Best Management Practices (BMPs) can provide a solution for on-site management of post-construction stormwater runoff. This study investigated the effectiveness of various BMP alternatives for retaining the first inch of runoff from highways and roads in Illinois with the Personal Computer Stormwater Management Model (PCSWMM) and idealized catchment areas. The modeled scenarios included pre-BMP construction when there is no BMP and post-BMP construction with bioswale, infiltration trench and vegetated filter strip. The effects of vegetated covers such as turf or prairie grass on infiltration of various soil types with and without BMPs were also evaluated. For all scenarios, one-inch rainfall 24-hour accumulated precipitation was applied. Typical dimensions and sizing for BMPs were extracted from Illinois Department of Transportation (IDOT) projects. This study found that runoff reduction for bioswale, infiltration trench, and vegetated filter strip are 70 to 83%; 100%; and 68 to 78%, respectively. Results also showed that prairie grass cover is more effective than turf grass in reducing runoff on various soil types.