Construction of new sewer and storm-water tunnel underway

By Devon Litster

Construction has begun on a huge downtown sewer and storm-water tunnel — considered critical to cleaning up the Ottawa River — that will run the full north-south length of Centretown along Kent Street.

The massive Combined Sewage Storage Tunnel, a multi-year, $232-million project funded by the City of Ottawa and both the federal and provincial government, includes the installation of a massive, three-metre-wide pipe below Kent Street and a second, east-west tunnel and pipe from LeBreton Flats to New Edinburgh.

The CSST, scheduled for completion in September of 2019, is the single biggest component of the 17-project Ottawa River Action Plan, a 10-year, $380-million modernization of Ottawa’s sewage and storm-water management system.

The city announced preparations to begin tunnelling the Kent Street portion for the CSST on Oct. 24. Equipment being used for the project, including a bright yellow overhead crane now towering above the Queensway, currently occupies a sprawling construction zone at the intersection of Kent and Chamberlain streets.
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The overall goal of the project is to reduce the frequency of sewage overflow into the Ottawa River during storms. During major rainfall, the water can carry sewage over into the Ottawa River, contaminating it downstream.

The CSST along Kent Street will run north to a site behind the Supreme Court, where it will intersect with the river.

Bert Hendriks, executive vice-president of Tomlinson Group, a company involved in the project, said the tunnel-boring machine is now being assembled underground.

“It’s a very large machine so we have to put it together underground piece-by-piece,” he said. The machine is expected to take two months to fully assemble, and another four months to finish the first stretch of tunnel.

In addition to reducing runoff into the river, the CSST is also expected to decrease the risk of basement flooding for houses in low-lying areas of the Glebe and southern Centretown. The CSST will also increase the flexibility of major collector sewers and lessen the burden placed on them, according to the initial CSST plan outline on the City of Ottawa website.

Meredith Brown, head of the Ottawa Riverkeeper environmental group, said although the project is still a few years from completion, the effect on the water will be almost immediate.

“Once it’s complete, it will be an immediate change. We’ll be able to see a difference in what’s going into the river after rainfall… It’s going to have an impact on everything in the National Capital region and everything downstream from it,” said Brown.

Brown said in the aftermath of one of the rainiest years on record in Ottawa, the CSST cannot come soon enough.
“Climate change predictions are saying that the expectation is more severe storms,” she said. Brown said cities must make changes in order to keep up with the weather.

Hendriks said that though the construction company is trying to make changes efficiently, it has run into complications.

“The process is going slower than we expected… there have been problems with Public Works and [other] government agencies slowing us down,” he said. “People change their mind all the time… We have to keep redoing proposals.”

He described how a plan for construction activity at a Public Works parking lot was delayed for six months before permission was granted to move forward with the project.

“We hope to complete sooner than the original date, but it all depends on how well the tunnel boring machine actually works,” he said.

Hendriks said completion is expected around September 2019.