Combined Sewage Storage Tunnel (CSST) – City of Ottawa

Combined Sewage Storage Tunnel (CSST) – City of Ottawa

(Theme 6 – Natural Capital, Theme 8 – Health)

Organization: City of Ottawa

Timeline for Completion: Start 2016 and Operational in fall 2020


The Combined Sewage Storage Tunnel (CSST) is one of the most important projects of the Ottawa River Action Plan (ORAP), which is the City of Ottawa’s roadmap to protect the Ottawa River for future generations.

The CSST will greatly reduce the frequency of sewage overflows during storms from entering the Ottawa River, and will help protect the river. These tunnels will hold up to 43,000m3 of sewer overflow during major rainfalls, the equivalent capacity of approximately 18 Olympic sized pools. Once rainfall has subsided, this water will then be treated and returned safely to the Ottawa River.

The CSST project is a $232.3 million investment and part of the Ottawa River Action Plan. Funding is being provided by the Government of Canada, the Government of Ontario, and the City of Ottawa. The Government of Canada and Province of Ontario are each providing $62.09 million. In addition, the City has committed $108 million.

The CSST is about 85-percent complete, with a rollout date of fall 2020.


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Project entered on: August 30, 2019 at 12:52 pm

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