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Montreal Backs Off Dumping Massive Amounts of Sewage in St. Lawrence River — For Now

The massive flow of sewage was pitched as a necessary move this week by the city, and quickly provoked a backlash from political opponents. But one expert says there probably isn't another option.
Photo via Flickr user Márcio Cabral de Moura

Montreal has suspended a controversial plan to dump 8 billion liters of untreated waste into the St. Lawrence River.

The massive flow of sewage was pitched as a necessary move this week by the city, but quickly provoked a backlash from residents and political opponents who warned about the possible environmental consequences.

Today, at a meeting of the city's executive, officials had changed their tune.

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"The mayor, [Denis] Coderre has asked for a moratorium on the decision," city official Jacques-Alain Lavallée told VICE News in an email. "Therefore, the decision to go ahead with sewer operation is suspended until further notice."

Lavallée said the mayor wants "all options to be examined" before a decision is rendered. That could come in as little as two days.

Craig Suavé, a Projet Montréal city councillor, called the development a "positive step" but was also skeptical of how much the city can figure out quickly.

"This should've happened beforehand. There should be a contingency plan," he told VICE News. "Hopefully this will be a very productive two days and they consult all the possible water experts on this," he said.

— DenisCoderre (@DenisCoderre)September 30, 2015

If the city goes through with its plan, for seven days starting on Oct. 18, dirty water from Montreal boroughs LaSalle, Verdun, and Notre-Dame-de-Grace will gush into the St. Lawrence River, which is the gateway from the Atlantic Ocean to the Great Lakes. That's the equivalent of 2600 Olympic-sized pools.

This is the only solution the City of Montreal could come up with to deal with the closure of a major sewer interceptor during construction of the Bonaventure Expressway.

City spokesperson Philippe Sabourin had told reporters on Tuesday that "there is no other choice" and that the river has a "significant dilution capacity," meaning that there wouldn't be any long-term damage. CBC News reported that the city used to clear out its sewers this way, as recently as the 1980s, before it became unacceptable.

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Although Ronald Gehr, a civil engineering professor at McGill University whose research includes wastewater treatment processes, said the action is "not a good idea unless the circumstances force one to do it," he agrees there isn't really another option.

If the sewer — one of two major interceptors in Montreal — is compromised during the construction of the expressway, he explained, there's no choice but to dump the waste into the river. He added that the plume will eventually be significantly diluted, but that dilution doesn't happen immediately.

"Close to the discharge point, the dilution will be almost zero, but as the plume proceeds downstream, by about 10 kilometres, it'll be diluted about 500 times," he said.

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The only long-term problem Gehr foresees is the accumulation of sediments.

"What the current sewage treatment plant does is it removes about 70 or 80 percent of the particles in the raw sewage, so that would not be removed and then they would settle out in the river," he explains. "The treatment plant also removes the same amount of phosphorus, so in the summer that might be quite bad."

As for the drinking water, Gehr says towns that are downstream "might have to be more careful with their disinfection. They might see a slight increase in E. coli, but it would be quite small."

The only alternative solution is planning the construction in a way that doesn't affect the sewer altogether, he says. "Once the sewer has to be compromised, I don't see any other solution."

Gehr does feel the public's reaction to the news may have been overblown.

"Of course it sounds terrible, but when you look at it rationally, it's not quite as bad as it sounds."

Follow Tamara Khandaker on Twitter: @anima_tk

Photo via Flickr user Márcio Cabral de Moura