The effects of urbanization on water resources in the United States and around the world have been well documented by scientists and engineers. Traditional storm sewer systems coupled with detention basins have historically been implemented to mitigate the increased stormwater runoff volume and peak flow rates from urbanized areas. However, this solution has been found to exacerbate the problems associated with increased peak flow rates and runoff volumes in the receiving streams by extending the duration of bank-full flows. Future effectiveness of addressing urbanization must seek to mimic the natural hydrologic processes that occurred prior to urbanization. Low Impact Development is an alternative approach to sewer systems that has been implemented to promote the natural hydrologic processes including evaporation, infiltration, and transpiration. However, detailed full-scale water quantity performance data is scarce. To address this knowledge gap, the following research objectives were developed: (1) evaluate the influential factors that impact infiltration rate in engineered soils, (2) determine the relation between the percentage of unfilled pore space, soil compaction, and plant health, (3) analyze the overall health of the planted community, and (4) evaluate how the bioretention systems have modified the surface runoff hydrograph with respect to change in total volume, the time to peak, the peak flow rate and the overall shape of the runoff hydrograph. An EPA SWMM model was developed to analyze the Michigan Avenue bioretention facilities. Results indicate that a viable alternative exists to the conventional stormwater drainage system that provides substantial reductions in runoff volume, peak flow rates, and increase the time of concentration while changing the overall shape of the runoff hydrograph. Additionally, improvements in data collection and performance testing were provided.
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