The city of Toronto has nearly completed the first phase of a massive, roughly $2.2 billion project designed to eliminate frequent combined sewer overflows into the Don River, the city’s inner harbor and a local creek that flows into the river.
The centerpiece of the sprawling, six-phase project, which is expected to be completed around 2037, is a network of three interconnected, concrete-lined deep tunnels — roughly 13½ miles long in total — that will hold CSOs until there’s sufficient treatment capacity available. The project also includes 12 wet-weather flow storage shafts that connect to the tunnels and seven offline storage
