Safely Digging a New River

Waterfront Toronto came together in 2001 to tackle big issues along the waterfront and as part of this work, we’ve been responsible for the dramatic transformation of contaminated lands. Our work on the beloved park Corktown Common and the entire West Don Lands, is an example of how we can turn industrial lands into a sustainable, mixed-use, riverside community that puts people at the centre by design.

We hope to bring the same kind of transformation to the Port Lands. But before we can do anything, we must begin by cleaning the soil that has become contaminated after years of industrial activity in the area. Our plan to create a new river valley through the Port Lands is complicated by that fact that we are working on land built over a marsh, some of which is contaminated, surrounded by water and connected to Lake Ontario.

Our challenge is to complete the project so that we can undo the negative effects of industrial activities in the Port Lands while safeguarding Lake Ontario or the Don River. This will involve a combination of soil excavation and treatment. Much of the soil we excavate will be treated within the construction site.

The approach we take to environmental management is based on results from remediation pilot tests recently completed in the Port Lands as well as reviews and consultation with regulatory agencies, project partners (including the City) and stakeholders (land owners, tenants, community and indigenous communities).

What have we done so far?

Working with the City of Toronto, Toronto and Region Conservation (TRCA) and CreateTO, we completed a Due Diligence exercise – a process that included assessing environmental conditions in the Port Lands – to ensure our plan to flood protect and revitalize the Port Lands could work. Those findings tell us what types of contaminants are present and where. We are also conducting a Community Based Risk Assessment (CBRA) for the entire project area. A CBRA helps determine how changing an area’s land use – for instance, from a parking lot to an office building – can affect the environment. It will give us confidence to make the right choices when it comes to protecting people and the environment. To help manage any potential effects on the environment, we also developed a Remediation and Risk Management Plan through the CBRA process. This was a requirement of our approved Don Mouth Naturalization and Port Lands Flood Protection Project Environmental Assessment.

Soil treatment pilot testing

We’ve tested technologies to help us clean and stabilize soil in the Port Lands before we start digging the new river. This will allow us to reuse the soil we excavate in the Port Lands to raise grades along the new river edge, green spillway and Keating Channel, protecting these lands from flooding.

In 2016, we requested technical proposals for innovative but proven technologies to address the environmental and geotechnical challenges of this project. We chose 13 technology companies to conduct lab tests using soil samples from the Port Lands, six of which  completed pilot tests in the Port Lands before we chose the ones that will work best with the qualities of soil in the Port Lands.

Having also conducted extensive surveys to assess the state of the soil throughout the project area, we’ve chosen a variety of approaches to excavating the kilometre-long river valley, a new Sediment and Debris Management Area south of the Keating Channel, and a third outlet for the river, the Don Greenway.

What will happen during construction?

The river valley will be excavated in stages. During excavation, we’ll take extra measures to secure any contaminants in existing soil or groundwater and make sure the new river is protected. For example, we’ll build a temporary barrier during construction to isolate each section of the river valley as we excavate. 

The soil, groundwater, lake water and air in our project area will be tested continuously during construction. We’ll also continue testing the health of the natural environment after construction is complete. Find more details about how we will manage contaminated soil and protect groundwater and lake water during construction in Section 6.5 of the Don Mouth Naturalization Environmental Assessment (DMNP EA). Find other requirements related to long-term monitoring in Section 8 of the DMNP EA.