Point-St-Charles | Building on “garbage juice”.

After decades of fallow land, Montreal is officially ready to begin the redevelopment of downtown Montreal’s most polluted sector: a peninsula floating on “garbage juice.”

The Pointe-Saint-Charles Business Park, located on the Bonaventure Expressway between the Champlain and Victoria bridges, was a dumping ground for a century until the 1960s. Meters of debris piled up in the river.

Montreal now hopes to attract green businesses.

The big change? Without much fanfare — because of the pandemic — a new system to capture and clean underground “waste juice” went into operation last year. Fluid is continuously collected using 23 wells before being pumped to a small treatment plant located on site. Two subterranean partitions are to prevent pollutants from flowing into the river.

At this point in the St. Lawrence “in 2012, there were obvious observations of hydrocarbons on the surface of the water”, recalls Marie-Andre Magar, head of the environment of the management committee of the city of Montreal. “We had an obligation to filter this ground water. […] We have put an end to an environmental problem that has dragged on for years, decades. »

New factory

Pres The first media visit to these facilities was possible in December.

On site, two separate machines process the diluted “garbage juice” that is collected by collection wells to remove two main contaminants: hydrocarbons on the one hand and ammonia – organic waste resulting from decomposition – on the other.

The set looks like a small sewage treatment plant. No smell disturbs the visitor’s nostrils.

“We analyze 100% of the flow [d’eau contaminée] Who is entering,” explained Claire Merkert of the City of Montreal’s Department of the Environment, in front of a map of the department. Large concentrations of hydrocarbons and ammonia are often found in the same places, but this dirty soil still holds many mysteries. “There is trash, ash, all kinds of stuff. We more or less know what it is,” said M.^me Merkert. “When they dug up the wall, they had surprises”, the city’s engineer Marian Arizabalag added: tires, cement blocks, organic matter.

Once the contaminated water is treated at the plant, it is diverted to the municipal sewage system, where it is treated before returning to the river. The removed impurities are buried. The city of Montreal is looking for a way to recycle ammonia-contaminated sludge with nitrogen, probably in agriculture.

At this time, all signals about the performance of the system are green, indicated M^me Arrizabalaga: “We can no longer see a rebound of hydrocarbons” in the river.

The factory itself was built over a century of rubble. “It’s waste, so it decomposes, sinks, but not evenly,” said M.^me Merkert. Hence all the pipes should be modified so that they do not break on the slightest movement of the building.

Unlike a classic cleanup project, there is no problem with excavating to clean up the soil: it will take decades, perhaps a century, for the field to be considered contaminated.

Future “Employment Hub”

For the city of Montreal, there is no question of waiting at this point.

Montreal soon “wants to redevelop this site,” said Marie-Andrée Mauger, head of environment at the Plante administration. “It still represents a large perimeter two or three kilometers from the city center. »

Already, in the past few years, some buildings have been built on the old dump site. The large MELS film studios, in particular, are two commercial buildings. They are built on piles anchored to rock, cannot have foundations and have special systems to manage the risk of biogas intrusion.

But by clearing the land, the administration hopes to speed up the establishment of companies and “work upstream of the environmental crisis.”

“We’re really aligning the department’s planning with Bridge-Bonaventure’s growth plan,” he continued. We are trying to create a job center that focuses on environmental change. »

M^me Mauger was pleased to complete a project within budget and schedule.