Modeling of Sedimentation in Stormwater Detention Basins

To minimize the non-point source pollution from roadway surface, the Texas Department of Transportation (TxDOT) initiated a research project for design of a small footprint non-proprietary detention basin, which consists of pipes and box culvert sections with specialized inlet and outlet system. A conceptual model was developed to estimate particle removal efficiency of the rectangular detention basin for the treatment of stormwater runoff by extending ideal horizontal tank theory under the condition in which water level is varied. A physical model was built in 1/5 scale of the prototype to measure its particle removal performance and verify the conceptual model. Several experimental runs were conducted using the physical model with steady inflow conditions, but various inflow rates, durations, and suspended solid concentrations (SSC). Measured time series outflow SSC and particle removal efficiency conformed closely to the calculated results from the conceptual model although the measured particle removal efficiency in the physical model was always few percent better than the predicted result using the conceptual model.