UBC Theses and Dissertations

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UBC Theses and Dissertations

Source controls for runoff treatment : hydrologic response and water quality attenuation in urban catchments Stime, Samuel Eugene


The lower Fraser Valley receives considerable rainfall, the vast majority of which percolated to groundwater for summer recharge of streams that supported healthy ecosystems and robust salmon populations. But as the cities in the valley grew and expanded, land use rapidly changed and impervious surface area from roads, parking lots, and buildings, like elsewhere, have contributed to increased flooding events, reduced groundwater recharge, lower summer base flow in urban streams, and reduced water quality that has led to significantly compromised biotic integrity and reduced biodiversity in the streams. Low impact development best management practices that promote infiltration of rainfall where it falls, reduce peak runoff flows and total event runoff volumes, and offer a level of treatment of contaminated waters, are slowly gaining recognition and use. This investigation was performed in two parts. First, using a paired catchment approach in the Township of Langley, it examines whether reductions in peak runoff flow and total event runoff volumes are proportionate to the effective reduction in directly connected impervious area, by installation of a suite of on-lot best management practices in one catchment. Second, using a treatment effectiveness approach in the District of Maple Ridge, it examines whether a roadside infiltration swale is removing contaminants and improving water quality both as predicted by the literature, and as required by Canadian guidelines for the protection of aquatic life. By disconnecting roof areas from direct connection to storm sewer, amending soil depths, and installing on-lot infiltration trenches in the Routley catchment in the Township of Langley, the hydraulic benefits are nearly as great as the scope of practices applied. Years after construction of a progressive suite of practices in Maple Ridge, the Foreman Drive bioswale appears to be removing contaminants as designed, and providing significant water quality benefits.

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