Combined Sewage Storage Tunnel now operating

The City has started operations of the Combined Sewage Storage Tunnel, a major investment to protect the health of the Ottawa River.

The Combined Sewage Storage Tunnel is one of the most significant projects of the Ottawa River Action Plan, which is a roadmap to protect the river for future generations. Construction began in 2016 on the two interconnected tunnels, which total 6.2 kilometres. The tunnels intercept surface runoff and wastewater (called combined sewage), store it temporarily, send it for treatment at the Robert O. Pickard Environmental Centre, and return it safely to the Ottawa River. The project also includes 15 underground chambers and access shafts and four odour control facilities.

Now in operation, the Combined Sewage Storage Tunnel will significantly reduce the frequency of combined sewage overflows to the Ottawa River, bringing the City into compliance with Ontario Ministry of the Environment, Conservation and Parks guidelines. It will reduce the volume of combined sewage overflows to the Ottawa River by up to 43,000 m3 per event – or approximately 18 Olympic-sized swimming pools – while also reducing the risk of basement flooding for approximately 7,000 residential properties in the north end of the Glebe and in Centretown. The tunnels also allow flow to be diverted from a major downtown sanitary sewer for improved inspections and maintenance on this critical infrastructure.

The Combined Sewage Storage Tunnel is a $232.3 million investment and part of the Ottawa River Action Plan. Funding was provided by the Government of Canada, the Government of Ontario, and the City of Ottawa. The Government of Canada and Province of Ontario each provided $62.09 million. In addition, the City contributed $108 million.

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Address: 110 Laurier Ave W, Ottawa, ON K1P 1J1