LRT tunnel waterproofing 'compromised,' transit commission hears

The waterproofing systemfor the Confederation Line tunnel is compromised, causing higher-than-expected leaks and ice buildup in the winter, the transit commission heard Thursday morning.

The partial shutdown of the LRTover two weekends at the end of April and beginning of May, characterized by city staff earlier this week as "regular maintenance," is actually part ofa four-phase process to identify and fix problems with the waterproofing.

• Middle of LRT line to close for 2 weekends for maintenance

Nicolas Truchon, CEO of the city's contractorRideau Transit Group (RTG), told transit commissioners the tunnel isthe light rail system's most complex piece of infrastructure. RTG is tasked with maintainingthe tunnel over the 30-year life of its maintenance contract with the city.

While the tunnel isdesigned to manage expected leaks through a drainage system, "some of the tunnel sections have seen water leaks above the expected levels, especially around Rideau station and extending toward the east,"Truchon said.

The excessive tunnel leaking has been an issue since day one.Truchon said workers have injected grout multiple times over the past three years to try to seal up leaks, but "that just seems to have moved the problem to other locations."

Leaks could affect LRT during winter

Transit commission heard the LRT is safe to ride, but the tunnel leak problems could affect the reliability of the Confederation Line.

"It's not safety-related, this is clear, and I'mconfident on that," said Rene Amilcar, the city's general manager of transit. "However, weknow that we have to do that [work]toavoid ice buildup in the winter and to avoid operational problems during the winter."

David Rheault, the senior tunnel engineer with Dr. Sauer & Partners tunnel experts hired by RTG told the commissionelements of the waterproofing systemare "compromised" and water is travelling behind the membrane.

The solution might not be simple, either, because the problem could be at a different location than where the leaks are occurring, the transit commission heard.

RTG will usethe two partial weekend shutdowns to further investigate the problem and possibly apply a short-term fix. Officials hope the long-termfix will be implemented in June during the usual LRT maintenance period, which will likely see the Confederation Line partially closed for two weeks.

It's not clear exactly how the tunnel leakage will be permanently addressed, but RTG will pay for the work.

"The situation we have in the tunnel is one we are treating with the highest level of priority because if it's not being looked after, that could lead to service interruptions down the road, and that's what we want to avoid," said Truchon.

River ward Coun. Riley Brockingtonsaid he did not consider the work on the tunnel to be a "type of regular maintenance," as was indicated by a memo Amilcar sent to members of council on Wednesday.

Brockingston said he understands that regular maintenance on the tunnel is to be expected, "but for this to happen on a brand new LRT is not normal."