EFFECTS OF SEDIMENTS ON BMPS FOR HIGHWAY RUNOFF CONTROL

Numerous studies conducted on highway stormwater runoff and its control with Best Management Practices (BMPs) indicate that sediment is the major pollutant that affects performance and longevity of BMPs. Currently, there are several knowledge gaps related to the effects of sediments on highway BMPs: a) how much sediment will be generated by a construction site by a section of highway with its surrounding watershed under different conditions; b) how sediment is intercepted by different BMPs with or without pretreatment sections; and c) what are the effects of these sediments on BMPs’ hydraulic behavior, longevity, and pollutants removal or release. The objectives of this study are to: 1) develop models to predict both surface runoff and sediment yield from highway systems under different conditions; and 2) evaluate how to incorporate models into design and management of BMPs for highway runoff control. RUSLE2 was used to estimate sediment yield for different settings (e.g., construction sites, different highway sections) under different environmental (e.g., soils, vegetation, slopes) and weather conditions (e.g., different rain events). Several highway sites across the state were selected to model runoff and sediment delivery under various construction scenarios. Several BMP designs were modeled at each of the highway sites to assess how the sediments would affect longevity of the BMP. Results indicate that BMPs reduce pollutants within channels. The data also points to BMPs on stabilized sites having higher efficiencies and longer lifespans. The developed models will assist in the planning, design and management of structural BMPs for highway runoff control. Advisor: John Stansbur