St-Charles | Building on “garbage juice”.

St-Charles | Building on “garbage juice”.

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

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

Montreal is now hoping to attract green businesses.

The big change? With little fanfare – because of the pandemic – a new system for capturing and cleaning underground “waste juice” went live last year. Liquid is continuously collected via 23 wells before being pumped to a small on-site treatment plant. Two underground partitions are designed to prevent pollutants from flowing into the river.

Photo by Robert Skinner, The Press

A series of wells collect the “waste juice” and direct it to the treatment plant.

At this point in the St. Lawrence River, “there were obvious surface observations of hydrocarbons in 2012,” recalls Marie-Andre Magar, director of the environmental department of the City of Montreal’s management committee. “We had a duty to filter this groundwater. […] We have put an end to an environmental problem that has dragged on for years, decades. »

New factory

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

On site, two separate machines process the diluted ‘waste juice’ collected from collection wells to remove two main contaminants: hydrocarbons on the one hand and ammonia – organic waste produced during decomposition – on the other.

The set looks like a small sewage treatment plant. No smell disturbs the nose of the visitor.

Photo by Robert Skinner, The Press

Marion Arizabalaga, City of Montreal Engineer, and Claire Merckhardt, City of Montreal Environmental Protection Agency

“We analyze 100% of the flow [d’eau contaminée] Who’s coming in,” explained Claire Merkert of the City of Montreal’s Department of Environmental Protection in front of a plan from the department. Large concentrations of hydrocarbons and ammonia are often found in the same places, but this filthy soil still holds many mysteries. “There is rubbish, ashes, all sorts of things. We more or less know what it is,” Ms. Merkert said. “When they excavated the wall, they got surprises,” added urban engineer Marian Arizabalag: tires, cement blocks, organic matter.

After the contaminated water is treated at the facility, it is diverted to the city’s sewage system, where it is treated before being returned to the river. The removed impurities are buried. The city of Montreal is looking for a way to recycle ammonia-contaminated sludge with nitrogen, likely in agriculture.

At this point, all the signals about the performance of the system are green, Mme Arrizabalaga said: “We can no longer see any recoil of hydrocarbons in the river”.

It’s not necessarily the most economical solution we chose, but it does end the migration for good. [contaminants].

Marion Arizabalaga, Engineer at the City of Montreal

The factory itself was built from rubble over a century. “It’s waste, so it decomposes, sinking, but not evenly,” Ms Merkert said. Therefore, all pipes should be modified so that they do not break at the slightest movement of the building.

Unlike a classic remediation project, excavation to remediate the soil is not a problem: it will take decades, maybe a century, before the field is considered contaminated.

Future “workplace”

Waiting and waiting is not an option for the city of Montreal at this point.

Montreal “plans to redevelop this site soon,” said Marie-Andrée Mauger, director of the Plante administration’s environmental department. “It still represents a large perimeter, two or three kilometers from the city center. »

Photo by Robert Skinner, The Press

The future MELS studio buildings will be built on piles anchored in bedrock

Some buildings have already been erected on the old landfill in recent years. Above all, the large MELS film studios are two commercial buildings. They are built on piles anchored in the rock, can have no foundations and have special systems to manage the risk of biogas infiltration.

But by clearing the land, the administration hopes to speed up business creation and “prepare for 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. »

Mme Mauger was delighted to complete a project on budget and on schedule.

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