Sewage tunnel project 6 months behind schedule, city says

CBC News | Posted: April 18, 2018 6:24 PM | Last Updated: April 18, 2018

Construction on massive project won't wrap up until at least 2020

Image | Tunnel Boring Machine

Caption: The six-month delay is partly due to 'challenges' encountered while commissioning and assembling the tunnel boring machine that will carry out the digging, according to a memo from Alain Gonthier, the City of Ottawa's director of infrastructure services. (City of Ottawa)

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A massive downtown tunnel project intended to keep sewage overflows from spilling into the Ottawa River is running roughly six months behind schedule, the City of Ottawa says.

Construction on the $232.3-million Combined Sewage Storage Tunnel was expected to wrap up by 2019 but will now extend into 2020, according to a memo from Alain Gonthier, the city's director of infrastructure services.

$232M sewage tunnel project aims to keep Ottawa River clean

Sewage tunnel dig to begin later this fall under Kent Street

The delay is partly due to "challenges" encountered while commissioning and assembling the tunnel boring machine that will carry out the digging, Gonthier said.

"As with any complex construction project, opportunities to recover and/or mitigate this construction delay over the next 24 months are being pursued and evaluated," he said.

Image | combined sewer storage tunnel map ottawa

Caption: This map shows the path and various construction sites of the forthcoming Combined Sewage Storage Tunnel, intended to prevent sewage overflows from spilling into the Ottawa River. (City of Ottawa)

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View a PDF of the map here

Construction started 2 years ago

During major rainfalls, the tunnels will hold up to 43 million litres of surface runoff and wastewater — as much as approximately 18 Olympic-sized pools.

Once the rainfall subsides, the water will be treated before being returned to the Ottawa River.

Ottawa sewage overflow in 2017 even more than future tunnel could handle

Work began in June 2016 on a shaft that would grant access to the tunnel at the intersection of Kent Street and Chamberlain Avenue.

Last October, the city announced the 23-metre deep shaft was complete, and that work to assemble the boring machine underground was underway.

Image | Kent Street entrance

Caption: In his update, Gonthier also said there were delays associated with the initial tunnel shaft below Kent Street and Chamberlain Avenue. (City of Ottawa)

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Partially finished

Over the next few months, Gonthier said, crews will begin work at a number of other sites:

McLeod Street and Kent Street.
Catherine Street and Kent Street.
Cumberland Street and Wilbrod Street.

In addition to the delays related to the tunnel boring machine, the excavation of the Kent Street shaft and starter tunnel also took longer than expected, Gonthier said.

Gonthier said the machine is now in operation, and is boring northward under Kent Street at roughly 20 metres per day, five days a week.

Approximately 500 metres' worth of tunnel have already been installed, he added.

The project — which is being funded by the city, provincial and federal governments — remains on budget, Gonthier said.