22 April 2021
Roxanne Gratton, MSc (Geology), Environment and Sustainable Development Specialist at JCCBI, spoke to us about the Solution Bonaventure project, whose goal is to stop contaminated water from migrating into the St. Lawrence River.
Why was the Bonaventure project launched?
For over 100 years, the shore of the St. Lawrence River was used as a landfill for industrial and household waste that has caused major contamination problems. JCCBI therefore came up with concrete solutions to prevent contaminants from migrating to the river in the sector where the Bonaventure Expressway is under its responsibility.
There are two types of contamination in this area:
What is the Solution Bonaventure’s biggest challenge?
A project of this scale has many challenges. For example, we treat an average of 280,000 m3 of water per year. That amount could fill 112 Olympic-sized pools in a single year, or almost 10 per month! That quantity is huge, and dealing with it requires very specialized know-how.
The project is also in a very busy area of the city. The Bonaventure Expressway, which runs along the edge of our retaining wall, is one of the main ways to get in and out of Montreal. We have to coordinate a great deal to keep road traffic flowing during operational work.
What is so innovative about the Solution Bonaventure?
Building a barrier wall to contain contaminants is not a new concept. However, building one in such a small space between a river and a highway required innovative construction techniques.
One of these techniques involved “converting” the existing backfill into a retaining wall. We didn’t have the space to remove it and then build a conventional wall. We therefore injected a cement-bentonite slurry into the crushed backfill mixture, which let us recreate all the properties of a retaining wall.
What is the future of the Solution Bonaventure project?
This project is here to stay, as a century of contamination has left its mark. Fortunately, the Solution Bonaventure is protecting the river and the environment by capturing all of the contaminants in the area. Today, hydrocarbons no longer flow into the river. That is a great result, and the benefits for the environment are enormous.
The Solution Bonaventure was developed with funding from the Federal Contaminated Sites Action Plan (FCSAP). The project represents a truly concerted effort by federal, provincial and municipal authorities to restore ecological balance to the area.