Efficacy of Bioretention for Treatment of Stormwater in Semi Arid Cold Climates

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Low Impact Development technologies (LIDs) are modern stormwater management methods that can improve stormwater quality and reduce stormwater quantity. Bioretention, which involves vegetated depressions in the land surface, is one of these technologies. They has seen widespread implementation but primarily in an ad hoc manner and in regions of mild and warm climates, which are atypical of most climate zones in Canada. The knowledge of the underlying processes to remove pollutants is still lacking and hence, so are the practical tools necessary for predictable bioretention design. In order to equip engineering practitioners with the confidence to use such a technology in Canada, the benefits of bioretention in managing stormwater quantity and quality need to be clearly quantified, and the practical tools for designing bioretention need to be developed. The proposed research project will combine modelling with observations collected on facilities developed at different scales to answer the following questions: i) What are the underlying processes controlling the removal of pollutants (especially nutrients) in bioretention? ii) How can bioretention performance under different hydrologic conditions and different pollutant loadings be compared and evaluated? iii) How can knowledge obtained from bioretention facilities be used to develop predictive tools? iv) How does bioretention perform under varying Canadian climate conditions? The results from this project will not only provide useful and definitive technical information on bioretention, but the practical, useful tools necessary for bioretention design. Therefore, we propose to: (1) investigate bioretention systems to treat urban stormwater runoff with particular attention paid to the characterization of nutrients, sediment and volume attenuation in terms of their quantity and quality, through field monitoring of various land cover types; (2) examine the impacts of these pullutants on the long term performance of these systems; (3) develop modeling tools for urban storwmater runoff; and (4) develop recommendations using evidence based knowledge for enhancing guidelines and standards associated with urban stormwater management for better protection of our source water and ecosystems in Alberta and beyond.