Formatted Title:

Navigating New Waters in Toronto’s Port Lands: Design and Regulatory Pathways for Environmental Barriers in New River Construction

Background/Objectives:

The Port Lands Flood Protection project, being undertaken by Waterfront Toronto in collaboration with the City of Toronto, Toronto and Region Conservation Authority, the Province of Ontario and the Federal Government of Canada, is one of the largest infrastructure projects in North America. The project will flood protect 740 acres of land immediately east of downtown Toronto at the shore of Lake Ontario, create over 60 acres of publicly accessible green space, and enable the development of a new community with 9000 residential units. The Port Lands was created through infilling large wetlands at the turn of the last century, land that later was extensively used for heavy industry. Contaminants include free phase petroleum hydrocarbons, volatile organic compounds, polycyclic aromatic hydrocarbons and metals. The flood protection, a requirement to unlock the land for revitalization, involves the construction of a new, ~1 mile long, naturalized river to safely convey flood waters into Lake Ontario. The new river alignment crosses environmentally and geotechnically poor soil necessitating the need for engineered environmental barriers to ensure the long-term protection of the new river valley from potential future incursion of contaminants, from upland areas that have not yet undergone remediation.

Approach/Activities:

The river valley environmental barriers designed to isolate and prevent migration of contaminants to the new river include a combination of vertical barriers, namely structural and non-structural secant pile walls, slurry walls, and clay berms coupled with horizontal barriers in the form of geosynthetic clay liner, geomembrane, and reactive treatment layers. The design was developed to not only meet the environmental requirements and utilize beneficial reuse of excavated material but to also integrate with Port Lands infrastructure: bridges, recreational areas, utility crossings, and Port Lands construction phasing including long-term operational maintenance of the naturalized river finishes and wetlands. The design evolution was led by intense project integration while mandating rigor in achieving environmental objectives.

Results/Lessons Learned:

The success of the River Valley environmental barrier design was rooted in development of an integrated, constructible, cost-effective, and technically feasible design that was based on a systematic, defensible design basis. As the project enters the final year of construction, the phased approach of the design and integration of the environmental barriers during construction serving as both environmental protective measures and hydraulic cutoffs demonstrated the success of the cohesive approach.

Laura Solano

Affiliation

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Navigating New Waters in Toronto’s Port Lands: Design and Regulatory Pathways for Environmental Barriers in New River Construction