Netami Stuart

Waterfront Toronto, Toronto, Canada

The Port Lands Flood Protection and Enabling Infrastructure (PLFP) Project is a $1.25B project led by Waterfront Toronto, the City of Toronto, Toronto and Region Conservation Authority (TRCA) and CreateTO, with the support and involvement of Ports Toronto, and funding from the three levels of government.  In addition to providing flood protection to approximately 250ha of flood vulnerable lands, this project will transform ~30 hectares of industrial brownfields into a naturalized, multi-outlet river valley system with associated channel spanning infrastructure, while unlocking the area for revitalization and facilitate billions of dollars in investment.  PLFP will improve quality of life, bring nature back to an underused industrial site and better protect our neighbourhoods from extreme weather conditions.

A comprehensive vision for the renaturalization of the river has been developed, recreating a river which then acts as an organizing structure for a system of new parks and public open spaces that will become catalysts for a range of memorable activities and experiences. At the intersection of two major systems – urban waterfront and natural river corridor – the project focuses on flood control, naturalization, and placemaking to bring the Don Valley and the Toronto’s public realm together in a robust and meaningful way.

This project allows the river and its associated parks and open space to shape and define the following neighbourhoods and the relationship of their inhabitants to the river. Additionally, innovative solutions have been proposed to knit both the roadway and the parks together, taking a systems-based approach to design.

This presentation will highlight the major project elements related to sustainable placemaking that combine to make the Port Lands Flood Protection and Enabling Infrastructure Project one of the most significant changes to the Lake Ontario shoreline in decades, and one of largest infrastructure projects in Canada.

Herb Sweeney

Michael Van Valkenburgh Associates, Inc., Landscape Architects, Cambridge, MA, USA

The Port Lands Flood Protection and Enabling Infrastructure Project (PLFP) presents a unique opportunity at a large scale for the public to have an authentic engagement with a functioning riverine condition within a highly urbanized environment – an experience of nature in the city. This presentation will highlight how public access is woven into the naturalization design for the mouth of the Don River, through the description of topographical features such as the Forest Frame, the meander, the levees, the gravel beach and the stone transitions. Areas such as the island in the Don Greenway will be discussed in terms of balancing human occupation with areas primarily intended for wildlife, which is a concept that informs the circulation and public area design overall. As Landscape Architects and team leader, MVVA used their experience with large park making to integrate the engineering design at the core of the constructed river with the upland park system to create a publicly accessible landscape that provides flood protection and hosts wildlife in real time. Constructed nature in the city is anticipated to become a more common 21^st century land use program, in response to ongoing urbanization and the environmental resiliency required to address global climate changes.

Marty Melchior¹, Nicholas Nelson², Sarah Widing², Kristen Covaleski³, Jonathon Kusa³, Emily Alcott⁴, Matt Cox⁴

¹ Interfluve, Madison, Wisconsin, USA

² Interfluve, Cambridge Massachusetts, USA

³ Interfluve, , St. Paul, Minnesota, USA

⁴ Interfluve, Hood River, Oregon, USA

The Port Lands Flood Protection and Enabling Infrastructure Project (PLFP) centers around the restoration of the lower Don River and its estuary. The naturalization of the corridor includes construction of a 1500 meter river valley segment, river channel and riparian wetlands. This presentation will review the hydrologic, hydraulic, geomorphic and ecological basis for the channel and wetland design aspects of the project. Analog and analytical design methods will be explored for channel bed and bank design, levee features, erosion countermeasures, plantings and habitat elements. Project constraints such as inundation frequency, contaminant and groundwater barriers, space limitations, bridges, ice and sediment will be presented, and their impact on design discussed. Habitat elements will be presented in detail, including large wood and stone applications for fish and waterfowl habitat, spawning habitat, bird roosting and nesting habitat, turtle nesting grounds and bat habitat.

Don Forbes

Waterfront Toronto, Toronto, Ontario

The Port Lands Flood Protection Project (PLFP) includes the construction of over 1 km of new naturalized river valley that extends from the mouth of the Don River through a formal industrial (brownfield) area as part of a comprehensive plan to protect the city’s downtown from flooding during a regulatory storm event and facilitate redevelopment of an historically industrial area with new parklands. The project involves the creation of a new multi-outlet river valley system through a combination of cutting into the existing contaminated soils and raising the grade of adjacent lands.

The placement of poor-quality historical lakefill over native lacustrine marsh soils (consisting of unconsolidated sand, peat and organic silts), combined with a high water table have resulted in very poor geotechnical conditions within the Port Lands. These lands were also home to extensive industrial activities for much of the 1900s and early 2000s. As such, the soil and groundwater are impacted with contaminants related to the historical industrial activity.  Additionally, the Port Lands soils are hydraulically connected to Lake Ontario and therefore difficult and expensive to dewater. Together these factors create an environment that is very challenging for construction.

The project design has taken into consideration constructability and long-term functionality associated with known environmental risks and the management of contaminated groundwater during and post-construction. The presentation will provide technical details of the various risk management measures used to address poor geotechnical conditions, environmental risks, and groundwater conditions to create 30 hectares of new aquatic and terrestrial habitat in the middle of a contaminated, former industrial, urban area.

David Kirkland, Chris Trevochka and Dmitri Perlov

EllisDon Civil Ltd., Mississauga, Canada

The Port Lands Flood Protection and Enabling Infrastructure (PLFPEI) project is comprised of 21 components with an overall project value of $1.25-billion funded by the City of Toronto, Province of Ontario, and the Government of Canada. The project is led by Waterfront Toronto with construction being managed by EllisDon. The PLFPEI project aims to mitigate flood risk of approximately 250ha of land prone to flooding. This is achieved primarily by conveyance of floodwater via a multi-outlet river valley system, but also involves flood protection landforms and valley wall features to block flow. In the process, approximately 30ha of industrial brownfields will be converted into a naturalized river valley ecosystem surrounded by park and play areas. To achieve this, approximately 2,100 m of secant pile and slurry cutoff walls were installed to prevent horizontal migration of contaminants, and in combination with a series of structural plugs, to achieve complete hydraulic cutoff and enable construction activities in the river valley to be conducted in dry conditions while occurring below the water table. During the river valley works, approximately 1,400,000 m³ of material will be excavated, with an intent to reuse as much of the excavated soil as possible in order to limit reliance of imported materials, which is achieved by stringent soil tracking and soil management plans. Waste water generated from dewatering activities required to facilitate the excavation is subject to a multi-treatment process with subsequent discharge into Lake Ontario. As an additional precaution to contaminant management and prevention of vertical contaminant migration into the newly constructed river valley, various risk management measures are utilized. Finally, given the nature of the project, marine construction comprises a substantial portion of the work, from construction of new dock walls, carp gates, stone revetment, timber crib walls, fabric encased soil lifts and other fish habitat features. The project anticipated completion the end of 2024.