Abstract Manager

The Edmonton Valley Line West Light Rail Transit (LRT) extension project is a 14 km at-grade extension of the Valley Line, stretching from downtown Edmonton to the western terminus at Lewis Farms. This project, representing the second stage of the Valley Line, includes 14 stops, 2 elevated stations, 2 km of elevated guide-way, the expansion of the Gerry Wright Operations and Maintenance Facility, a new storage facility at Lewis Farms, and all associated light rail transit infrastructure, including systems integration, testing, and commissioning.

In addition to the necessary drainage and municipal sewer system modifications due to the proposed road improvements and the new LRT extension, there was an opportunity to implement stormwater management (SWM) measures along the project limits to meet design requirements. Given the limited construction space, Low Impact Development (LID) measures were considered instead of traditional SWM facilities (e.g., wet ponds, wetlands, storage tanks) to address SWM quantity and quality control requirements. Linear retention/detention options within the City’s construction limits were incorporated into the SWM strategy, supported by a hydrodynamic modelling approach. The soil cell LID features were integrated with the landscaping design to fulfill both SWM and streetscaping requirements. The proposed drainage design was developed to accommodate the increased runoff resulting from the project works and to ensure that the municipal sewer system is not adversely impacted.

The Valley Line West LRT project was a design-build project governed by a Design-Build Agreement between the City of Edmonton and Marigold Infrastructure Partners (MIP). Existing guidelines addressed most design requirements; however, the City of Edmonton’s construction limits, the presence of various dry and wet utilities along the corridor, and compliance with horizontal and vertical clearance requirements posed significant challenges for the drainage and SWM LID design. MIP collaborated closely with the City and other stakeholders to address various issues that arose during design and construction by employing more complex hydrologic and hydraulic modelling.

Keywords: Hydrology, Drainage, Edmonton Valley Line West, Stormwater Management, Low Impact Development (LID)