MONTREAL — The sewer repair work that led the city of Montreal to dump raw sewage directly into the St. Lawrence river was completed three days early, the city announced Saturday.
In a statement, the city reported its wastewater was once again being treated normally after 89 hours of work.
Early Wednesday, the city began dumping billions of litres of raw sewage into the river to access and perform critical repair work on the support arches of a major sanitary sewer as well as relocate a snow chute.
The city said the amount of sewage dumped had been downgraded from an estimated 8 billion litres down to 4.9 billion since the work was completed in four days instead of seven.
The statement credited "the unwavering commitment of experts, technical staff and project partners" for the early finish.
The city had already announced late Friday that 17 kilometres of the sewer being repaired was reopened and wastewater was being treated in that sector again.
Preliminary results from the water-quality tests taken during the week were "broadly consistent with expected values" in most areas, the city said.
Jean-Francois Blais, who works with the Universite du Quebec's research institute, said earlier this week the discharge plume is probably not any more polluted than the water that is directly released from the treatment facility under normal circumstances.
"Everything that is soluble is not really removed by the treatment station," he said. "In the case of bacteria and micro-organisms, there isn't any disinfection that goes on."
He said the difference is that the treatment centre removes solid materials and phosphorus.
Blais also cautioned against reading too much into news reports that indicated the river water at some points is currently 40,000 times more polluted than normal.
"[The news reports] don't really have any value," he said. "You have to look at it from the bigger picture. Anyone would have been able to tell you that if you take a sample from contaminated water it's going to show it's contaminated."
He said in a few days the normal flow of the river will dilute the discharge and water levels will return to the way they were last week.
The city said more test results were expected Sunday.
With files from Pierre Saint-Arnaud
Morgan Lowrie, The Canadian Press