Toronto, Ontario, Canada

Waterfront Toronto

Michael Van Valkenburgh Associates (MVVA), Inter-Fluve, GEI

Our Expert:

As trends in urbanization and revitalization continue, cities are working to restore waterways to create vibrant connections between nature and the urban environment. LimnoTech worked on a team led by Michael Van Valkenburgh Associates (MVVA) on behalf of Waterfront Toronto, a local development authority, to design major redevelopment, flood protection, and naturalization of the Don River mouth on the Toronto waterfront.

The Challenge

The Lower Don Lands area of Toronto has suffered from neglect and urban decay, which are typical of many older cities. LimnoTech was part of a team led by MVVA. A broad range of experts across multiple disciplines were on the team, including urban planners, landscape architects, transportation and structural engineers, building architects, ecologists, and environmental and water resource engineers.

The challenge was creating a new scheme for planning and developing the Port Lands, a 300-acre block of land on Toronto’s waterfront that had been neglected for many years, in part due to flood risk. Finding a solution for the Don Lands and the mouth of the Lower Don required simultaneously meeting the City’s needs for residential, commercial, and industrial uses in the Don Lands area, conveyance of extreme flood events, and addressing the community’s strong desire to restore ecological function and recreation along the river.

How We Helped

LimnoTech brought its extensive knowledge of how rivers flow and move sediments to a collaborative working relationship with the ecologists and architects working on the project to “Engineer a River.” The team created a plan for the development of the Don Lands. Elements of the plan include the design of levees and flood protection landforms; the development of dams and flow control structures that manage both low flows for ecological benefit and extreme flows for flood protection; plans for navigational channel maintenance and dockwall modifications; and the design of bridge piers and channel armoring to manage flood induced scour.

During the detailed design process, LimnoTech developed a highly resolved 2‐dimensional flow and sediment transport models in MIKE 21 and EFDC/SEDZLJ to guide the rest of the design team in meeting the project flood protection requirements while informing the design of adjacent bridges and infrastructure systems and the ecosystem restoration. The detailed hydraulic design includes evaluating the proposed flood protection measures, including channel modifications, a new river outlet to the Toronto Inner Harbor, and an overflow spillway to the Ship Channel activated during high flow events.

The detailed hydrodynamic models were applied to inform the design of the ecosystem restoration, including evaluation of shear stresses and hydrodynamic forces on natural bank stabilization measures and analysis of the inundation frequency of the riverine wetland systems based on the seasonally varying Lake Ontario water levels and the river flows to guide plant selection. The sediment transport models were applied to evaluate the anticipated scour of the river beds during extreme flow events and to evaluate and design the long‐term maintenance strategy for the Sediment and Debris management area included upstream of the naturalized river mouth. Sediment scour during high‐flow events was evaluated with the sediment transport model to understand the impact of scour and deposition on the flood conveyance capacity and to ensure that adjacent dockwalls, bridge piers, and other infrastructure were designed to be protected during these high‐flow events.

The Outcome

LimnoTech’s experience in hydrodynamics and sediment transport, ecosystem restoration design, and applied urban geomorphology was key in informing the design. The team of scientists, engineers, and architects have developed an award‐winning plan for the development of the Don Lands area that is exceptionally well integrated. The plan includes a revitalized riverine ecology, comprehensive flood management, management of sediment and debris, and creation of recreational opportunities.

Construction on the Port Lands began in December 2017 and is currently estimated for completion by the end of 2024. Once complete, a multi-threaded river mouth will run through a vibrant new neighborhood in Toronto with a highly interwoven mix of commercial and residential development, multi-modal transportation infrastructure, parks, and recreational opportunities. There will be a corridor of river and wetlands that provide the required capacity for flood protection and restore ecological function to a major Great Lakes (Lake Ontario) river mouth.

The project is an economic boon to the City of Toronto, with the potential to add billions of dollars in economic value to the Canadian economy. We are proud of our role in this precedent-setting project and look forward to seeing construction completed in the near future.

This project has received several awards and recognitions, including being selected as one of 16 founding global projects of the Climate Positive Development Program by the Clinton Climate Initiative and the U.S. Green Building Council to demonstrate sustainable development of large-scale urban projects that show cities can grow in ways that are “climate positive.”


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