Ottawa's next big dig set to start on $230M sewage tunnels

Another big dig is set to start under Ottawa's downtown, this time to carve out tunnels with the capacity to store up to 43 million litres of raw sewage and runoff resulting from big storms.

Storage tunnels centrepiece of massive plan to clean up the Ottawa River

Tim Plumptre, president of the New Edinburgh Community Alliance, stands in Stanley Park near the city's odour control facility, which will be upgraded as part of the sewage storage tunnel project. (Kate Porter/CBC)

Another big dig is set to start under Ottawa's downtown, this time to carve out tunnels with the capacity to store up to 43 million litres of raw sewage and runoff resulting from big storms.

The combined sewage storage tunnel is the centrepiece of the Ottawa River Action Plan approved by city council in 2010, and aimed at preventing sewage from spilling into the waterway.

Two tunnels, each about three metres in diameter, will stretch six kilometres under the city core. When they're completed, they'll be able to hold up to 18 Olympic swimming pools of sewage and storm water.

One tunnel will run north-south under Kent Street from near Highway 417 to the Supreme Court on Wellington Street. Another, longer tunnel will stretch from LeBreton Flats in the west to New Edinburgh in the east.
Two intersecting storage tunnels, each three metres in diameter, will be built under Ottawa's core to prevent sewage and storm water from spilling into the Ottawa River. (City of Ottawa)

The project was expected to cost $195 million, when the Ontario and federal governments each signed on to contribute $62 million. The total project cost is now estimated at $232.3 million, with $108 million committed by the city.

A joint venture between Tomlinson and Dragados, the Spanish tunneling firm that is also digging Ottawa's light rail tunnel, won the contract in July to build the tunnel.

Tunnel construction will 'bisect' Stanley Park

Tomlinson-Dragados has started mobilizing on site, and construction will begin soon, according to the city's manager of infrastructure services, Marco Manconi.

The first dig site will be at Kent Street and Chamberlain Avenue, alongside Highway 417.

But perhaps the most visible sign of construction will be in New Edinburgh next summer, when a portal will be constructed in Stanley Park so trucks can remove material from the tunnel site.
The first portal to the storage tunnels will be located at Kent Street and Chamberlain Avenue, near Highway 417. (Kate Porter/CBC)

"It's going to bisect the park," said Tim Plumptre, president of the New Edinburgh Community Alliance.

The construction zone will be located between a popular spot for dog walkers and a playground.

"Safety, I think, would be a big concern, with the large trucks going through," said Plumptre.

Public meeting planned

The city plans to hold a public meeting this fall to address residents' concerns and inform them about next summer's construction, said ward Coun. Tobi Nussbaum.

"We're going to absolutely make sure that any of the truck movements that take place to and from the tunnel are done thoughtfully, carefully, recognizing that there are playgrounds in the area and residents live on those streets," he said.

Nussbaum said the city has plans to renovate the park after construction on the sewage tunnel is finished. That may even offer a chance to build a berm, he said, because New Edinburgh has long been vulnerable to spring flooding at that point on the Rideau River.

"It's not going to be great," said Plumptre of the upcoming construction in a picturesque park. 

"But on the other hand, it's a good thing the city is doing something about the sewage issue because having your raw sewage going directly into the Ottawa River is not the greatest thing either."