After decades of fallow land, Montreal is officially ready to launch the redevelopment of the most contaminated sector of the downtown area: a peninsula floating on the “garbage juice”.
The Pointe-Saint-Charles Business Park, located along the Bonaventure Expressway between the Champlain and Victoria bridges, was a dumping ground for a century, until the 1960s. river, with meters of rubbish piled to the bottom.
Montreal now hopes to attract the cream of green businesses there.
The big change? Without much fanfare – due to the pandemic – a new system for capturing and cleaning underground “garbage juice” came into operation last year. The liquid is collected continuously using 23 wells, before being pumped to a small treatment plant located on site. Two underground partitions must prevent contaminants from flowing to the river.
“In 2012, there were obvious observations of hydrocarbons on the surface of the water” of the St. Lawrence at this location, recalled Marie-Andrée Mauger, head of the environment on the executive committee of the City of Montreal. “We had obligations to filter this groundwater. […] We put an end to an environmental problem that had dragged on for years, even decades. »
The Press was able to make the first media visit to these facilities, earlier in December.
On site, two separate series of machines process the diluted “garbage juice”, collected by the collection wells to eliminate the two main contaminants found there: hydrocarbons on one side and ammonia – resulting from degradation. of organic waste – on the other.
The set looks like a miniature sewage treatment plant. No smell disturbs the nostrils of visitors.
“We analyze 100% of the flow [d’eau contaminée] who enters, ”explained Claire Merckaert, from the environment department of the City of Montreal, in front of a map of the sector. Large concentrations of hydrocarbons and ammonia are often found in the same places, but this filthy subsoil still holds many mysteries. There is “garbage, ashes, all sorts of things. We know more or less what it is,” said M.me Merckaert. “When they dug to make the wall, they had surprises”, added Marion Arrizabalaga, engineer at the City: tires, cement blocks, organic matter.
Once the contaminated water is treated in the plant, it is redirected to the municipal sewer system, where it will be treated again before returning to the river. The contaminants removed are buried. The City of Montreal is looking for a way to recycle sludge contaminated with ammoniacal nitrogen, probably in agriculture.
For the moment, all the signals are green regarding the performance of the system, indicated Mme Arrizabalaga: “We no longer see any resurgence of hydrocarbons” in the river.
It’s not necessarily the most economical solution we’ve chosen, but it puts a definitive end to the migration of [contaminants].
Marion Arrizabalaga, engineer at the City of Montreal
The factory itself was built on top of a century of rubbish. “It’s waste, so it degrades, it sinks, but not evenly,” said M.me Merckaert. All the piping must therefore be adapted so as not to break at the slightest movement of the building.
Unlike a classic decontamination project, there is no question here of excavating the soil to treat it: it will take decades, probably a century, before this sector can be considered as decontaminated.
A future “employment hub”
For the City of Montreal, there is no question of waiting all this time.
Montreal wants to quickly “redevelop this site,” said Marie-Andrée Mauger, head of the environment within the Plante administration. “It still represents a fairly large perimeter two or three kilometers from the city center. »
Already, in recent years, some buildings have been erected on the grounds of the former dump. Huge MELS film studios, in particular, but also two commercial buildings. They are built on piles anchored in rock, cannot have a basement and have specialized systems to manage the risk of biogas infiltration.
But by decontaminating the land, the administration hopes to accelerate the installation of companies and “act upstream of an environmental crisis”.
“We really organize the planning of this sector in coherence with the development plan of Bridge-Bonaventure, she continued. We are looking to develop a job center that will focus on ecological transition. »
Mme Mauger was pleased to conclude a project within budget and schedule.