Section of Ottawa LRT to be closed for two weekends as RTG looks to prevent water infiltration in tunnel

Passengers wait on the Rideau Station platform for an OTrain along the Confederation Line of Ottawa's LRT system. (CTV Ottawa)

A section of Ottawa's LRT tunnel will be closed to trains for two weekends this spring, as Rideau Transit Group looks to address water infiltration near Rideau Station.

Officials say the waterproofing system for the tunnel is compromised, causing water leaks "above the expected levels."

In a memo to council, transit services general manager Renee Amilcar says the downtown tunnel will be partially closed on April 29 and 30 and May 6 and 7, for "necessary maintenance assessment."

"This work must occur for Rideau Transit Group (RTG) to assess the scope of required repairs to prevent water infiltration in sections of the tunnel," Amilcar said.

"This type of regular maintenance is common for underground tunnels, and there are no safety concerns. This RTG assessment is necessary and will provide the basis for the development of a workplan for scheduled tunnel maintenance work in June."

Riders have long complained about an odour at Rideau Station.   Rideau Transit Group has said it believed the smell was due to "stagnant water" that was getting into the tunnel near Rideau Station in downtown Ottawa.

In 2020, the city said an environmental consulting firm was working to help determine what could be done to eliminate the smell.

O-Train service will run from Tunney's Pasture and Parliament stations in the west end, and between Hurdman and Blair stations in the east end the weekends of April 29-30 and May 6-7. R1 bus replacement service will run between Hurdman and Lyon stations during the partial LRT shutdown.

Amilcar says information will be provided to customers in advance of the shutdowns, and ahead of the maintenance work scheduled for June.

Waterproofing system compromised in LRT tunnel

Councillors on the Transit Commission were told Thursday that water appears to be travelling behind the final lining of the waterproofing remediation material in the tunnel, but officials don't know where the breach is occurring.

However, officials insist the water leaks are "not a safety issue."

"The tunnel is one of the most complex pieces of our infrastructure to maintain over the next 30 years," Nicholas Truchon of Rideau Transit Group said Thursday morning.

"The tunnel has been designed to manage water and water leaks through the drainage system, as water leaks are expected and normal. However, some of the tunnel sections have seen water leaks above the expected levels, especially around Rideau Station and extending towards the east all the way towards the east portal."

Truchon says Rideau Transit Group has tried grout "injections" to control water infiltration in the tunnel, but that may be "moving the problem to other locations."

"The problem needs to be looked at more at the waterproofing level," Truchon said.

The work to address water infiltration in the tunnel would be done in four phases, starting with investigating and testing and followed by localized remedial injection, "collect and drain" and a full structural repair.  The two weekend shutdown of the area between Parliament and Hurdman stations will allow staff to investigate and apply short-term fixes.

The outside expert hired by Rideau Transit Group to help address water infiltration into the transit tunnel says they believe the waterproofing system in the tunnel has been compromised, and work will be done in the weeks and months ahead to address that.

"Some elements of waterproofing system may be compromised or not properly embedded," David Rheault, senior tunnel engineer with Dr. Sauer and Partners, said. "We're doing some checks on those elements."

The section of the LRT tunnel will likely be shut down in mid-June to complete the repairs on the tunnel.

Amilcar says in June, OC Transpo will announce plans for the regular maintenance on the LRT system that will include grinding the track and other "things we will need to do."

Questions about maintenance

Several members of the Transit Commission questioned staff and RTG categorizing the maintenance to address the leaks in the tunnel as routine. RTG said workers would focus on addressing the leaks in the tunnel during the weekend shut downs at the end of April and May.

"Because we're being very surgical in terms of location, it does not open up the rest of the system to do a lot more," said Mario Guerra of Rideau Transit Maintenance.

Coun. Riley Brockington told the committee, "I accept the point that regular maintenance is normal on all public transit systems, but for this to happen so early on for a brand new LRT, in my mind is not normal."

"This is not regular maintenance."

Speaking on Newstalk 580 CFRA's Ottawa Now with Kristy Cameron, Coun. Wilson Lo said he's not convinced the work is "as routine as Amilcar tried to sell it."

"I do know that there is routine maintenance that has to be done in the tunnel, but I think the type of work we have to do this time might be unique to us."