THE EFFECTS OF FREEZE-THAW CYCLES AND STORMWATER RUNOFF INPUT ON THREE BIOSWALE SOIL MIXTURES

Urbanization and the growth of suburbs are world-wide phenomena. One product of this development is a dramatic increase in impermeable surfaces and a consequent increase in stormwater runoff. Bioretention cells (biocells) are one best management practice frequently used to mitigate the impacts of urban stormwater runoff. To ensure that a biocell will continue to perform adequately in the long term, it is imperative that the varieties of conditions it will sustain through time are considered during its initial design. Although biocells are frequently used for stormwater management, very few quantitative data exist on how they perform through time and in varied physical environments. In regions with seasonal freeze-thaw cycles, it is important to understand the physical effects of freeze-thaw cycles on biocell materials so that the integrity of the design will not be compromised by seasonal change. This project utilizes manufactured laboratory columns to investigate the effects of freeze-thaw cycles and runoff sediment input on the infiltration capacity of three different biosoil mixtures. These tests will provide an analog for long-term changes in biocell infiltration rates due to seasonal variations, which will provide critical data on which soil mixture would be best implemented in geographic regions susceptible to freeze-thaw activity. Furthermore these results will inform design standards for biocells to insure their long-term use.