Bioretention Cells (BC) are a Low Impact Development technology that provide distributed storm water management near to its source. Most research envisages BC as a black box with ambiguous processes between the input and the output. This thesis aims to consider BCs as heterogeneous systems with physical processes that vary both spatially and temporally. For this study, a 5-year-old BC at Kortright Centre for Conservation in Vaughan, Ontario is used as an investigation area. The following results were observed. D30 and D60 were lower in the central flow path due to sedimentation and suspended solids deposition. Organic content was negatively correlated with bulk density. Ksat in the central pathway region and non-central pathway region showed a mild rise during and a mild decrease respectively during warm winter days possibly due to freeze-thaw action. However, after statistical outliers were identified and removed from the Ksat data, this effect was not observed. iii Acknowledgments First and foremost, I would like to thank my Lord Jesus Christ for his grace and blessings throughout this research. I wholeheartedly thank my research supervisor Dr. Jennifer Drake for offering me the opportunity to carry out research. It would not have been possible to produce this thesis without her support, suggestions, constructive feedback, and professionalism. I would also like to thank Dr. Elodie Passeport for providing many helpful suggestions and for being the second reader. I would like to thank the Sustainable Technologies Evaluation Program (STEP) at the Toronto and Region Conservation Authority (TRCA) for providing the Bioretention Cell and for collaborating with me on this research. I would also like to acknowledge TRCA staff Mark Hummel, Jacob Kloeze, Tim Van Seaters, Christy Graham, and Dean Young for technical support and help with field work. Financial support for this work was provided by NSERC, MITACS and the University of Toronto. I would also like to acknowledge undergraduate interns Alexander Tonelli, Eric Wang, Redwan Baba and Diego Domingo for carrying out data collection during the summers of 2017 and 2018. My sincere thanks go to my colleagues