The City of Montreal’s Rehabilitation of the Pointe-Saint-Charles industrial park project is the 2020 winner in the brownfields category of FCM’s Sustainable Communities Awards.
The Pointe-Saint-Charles industrial park is built on part of a 123-hectare former landfill site. When contamination from the site was observed in the Saint Lawrence River, temporary containment and pumping measures were put in place until a more permanent, sustainable solution was identified. Now an impermeable barrier prevents further leakage, and an innovative treatment process is being used to remediate the site.
Project creates permanent barrier while toxins are removed
Since the project site was used as a landfill for 100 years, the contaminated material was as deep as 16 metres. To fully stop contaminant migration into the Saint Lawrence, the project team built an impermeable cement-bentonite wall to permanently block the flow of groundwater and associated contaminants and hydrocarbons. To remediate the brownfield site, water is pumped from a network of wells and directed to the appropriate treatment method for the type of contamination. This process is designed to limit the use of raw materials and generate less waste.
Remediation of the brownfield improves the area for residents, businesses
The environmental impacts of the project are being carefully measured to ensure the groundwater levels remain similar to what they were before the impermeable barrier was built, and to monitor contamination levels in the water being pumped. The system has the flexibility to automatically adjust the pumping rate as well as the treatment process. In addition, the project contributes to improving the living environment in the business park as part of the City’s urban development plan.
By remediating the site, the City will be able to improve residents’ access to the Saint Lawrence by redeveloping an expressway into an urban boulevard along the river and adding a bike path connecting the downtown area to the West Island and the South Shore. Over 200 trees will be planted on the site to foster ecological diversity and migratory bird nesting. With these improvements to make the industrial park more appealing, the City hopes to attract new businesses to the area, and in the coming years the City will be able to sell several lots, both economic benefits of the project.
Technical challenges led to innovative solutions
One of the challenges the project faced was the presence of ammoniacal nitrogen, which can be toxic to wildlife and contributes to deteriorating health of waterways. Few treatments exist, and the most common one is sensitive to changes in temperature, pH and effluent. The innovative struvite precipitation treatment that the project team used is less sensitive to change and produces a salt composed of nitrogen, phosphorus and magnesium that can be used as fertilizer, creating a virtuous circle. It is a new technology that can easily be replicated in other communities.
Another challenge the project faced was the construction of the barrier wall itself. Extensive investigative work and detailed plans were required to mitigate the risks of building among waste materials in an urban area with sensitive underground infrastructure, such as fibre optics.