Bioretention cell efficacy in a cold climate

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More recently, industry professionals have started to implement Low Impact Developments (LID) as a way of controlling runoff flow volumes, recharging groundwater and to improve water quality by intercepting and treating runoff at the source. One promising example of an LID is a bioretention cell. These are densely vegetated depressions in the land, commonly placed in parking lots and traffic islands, which capture and treat stormwater runoff. The long term impacts of pollutant loading and its effect on infiltration rates, removal efficiencies and on the bioretention system have not been widely explored. Furthermore, there has been little research into seasonal effects on bioretention performance, especially the efficiency during cold periods and during freeze-thaw cycles that are dominant in parts of Canada. This research will determine the efficacy of bioretention cells for attenuating stormwater hydrographs during spring freshet, during the summer, and during freeze-up in fall months; and determine the efficacy of these cells for removing total suspended solids (TSS), for leaching or retaining phosphorus, nitrogen (in its various forms), and chloride ions from the outlet of the system over seasonal conditions. The information will be disseminated to municipalities charged with stormwater mitigation in both cold and temperate climates. This will help them to provide better and more cost-effective LID designs.