Excavation complete on Ottawa’s $232.3M sewage storage tunnel

The machine boring out a new sewage storage system below the nation’s capital had a major breakthrough Monday, as the city announced it had finished excavating the six kilometres of tunnels designed to reduce pollution in the Ottawa River.

The city is developing a new storage facility for sewage waste separate from its existing combined sewer system, which sends untreated water into the Ottawa River during heavy rain and snow melts. When complete, the tunnel will hold the capacity of 18 Olympic-sized swimming pools.

The tunnel-boring machine finished the four kilometres of east-west tunnelling this week. Work began last year beneath New Edinburgh and concluded near LeBreton Flats, at times drilling nine storeys below city streets.

Work had already concluded on the two kilometres of north-south tunnel last year. With work remaining on underground chambers and odour control facilities, the city says it expects the full project to wrap up in 2020.

The city tapped contractors Dragados and Tomlinson to build the new combined sewage storage tunnel back in 2016. The $232.3-million project includes $62.1 million in funding from both the federal and provincial governments and an additional $108 million from the city itself.