Evaluation of Low Impact Development Models for Storm Water Flow Reduction and Demand Management in Downtown Seattle

The combined sewer overflow to Downtown Seattle's water front has been a problems for many years. The City has been evaluating different strategies to reduce the stormwater flows into City's infrastructure. One of the strategies is to evaluate low impact development (LID) alternative such as green roof retrofit, bioretention and porous pavement or the combination of any of them. This paper compares various LID models used to perform stormwater evaluations for Seattle's downtown basin. All models are running for continuous simulations for 29 year — 5 minutes rainfall data. Uncertainties associated with each model run are setup to assess the reliable reduction of stormwater flows.