Montreal sewage dump could see ships loaded with untreated water

Tanker ships full of untreated wastewater could become a reality in Montreal waters if the city's plan to release eight billion litres of raw sewage in the St. Lawrence River is approved by Canada's environment minister.

The ships are one of a number of mitigation and monitoring measures recommended by an independent panel of scientists commissioned by Environment Canada to assess the dump's potential impact on the environment.

The scientists recommendations were made public Friday.

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The panel said tanker ships could be used to take on excess sewage at one of the main discharge points.

The panel's recommendation challenged the City of Montreal's claim that filling tanker ships with the full load of sewage was impractical, if not impossible.

A study conducted by Montreal had found that it would take an estimated 200 ships with a load capacity of 36,000 tonnes each to do the job.

Questions remain

The panel's report said the city should reconsider the measure for some of the sewage, but did not go into what would happen with the wastewater once it is taken onboard.

Options could include treating the water onboard and then releasing it into the river, or transporting the wastewater to a treatment facility.

Aziz Gherrou, a researcher in water technologies with the CEGEP de St-Laurent in Old Montreal, said treating the water onboard would work.

"They could inject the same chemicals used at water treatment facilities — this would help," he told Radio-Canada.

Finding tanker ships that could handle such a task is yet another question raised by the report's recommendation.

Louis-Marie Beaulieu of the Desgagnés Group, one of Quebec's biggest shipping companies, said there are only 20 ships in all of eastern Canada that could handle such a task, eight of which are owned by his company.

He couldn't estimate how much such an operation would cost, saying it depends on the length of the operation, the number of ships required and other variables.

The cost per ship could run between $20,000 and $40,000 per day, he said.

Chartering ships from abroad is also a possibility, he said, but that requires time.

City experts and the independent panel said that the proposed dump has to happen during the fall, when the environmental impact would be minimized.

The decision to approve or refuse the sewage dump now rests with federal Environment and Climate Change Minister Catherine McKenna.

She said she would make a decision about what to do with the wastewater in the next 24 hours.