Longueuil set to start dumping raw sewage into the St. Lawrence

Longueuil is set to begin dumping raw sewage in the St. Lawrence River on Thursday.
Why is this being done?
Longueuil says it must remove and replace two six-metre-long sections of a sewage pipe at the bottom of the river that carries effluent from the mainland to a water-treatment plant on Île Charron. Workers discovered a leak in the 90-centimetre pipe in June. The cause is under investigation. Installed in 1990, the pipe was supposed to have a lifespan of 60 to 80 years.
Where is t