THUNDER BAY — City crews will be busy Friday and into the weekend repairing a large break in a water main just north of Thunder Bay’s Intercity area that took the better part of a week to find.
“So, we found a large failure in the water main directly underneath two 48-inch storm sewers that cross Fort William Road,” said David Warwick, Thunder Bay’s superintendent for water distribution and wastewater collection.
“It's been a challenge for the staff to get to, first identify the leak, and now excavate to prepare for repairs of it.”
The affected water main is about two metres below ground, Warwick said.
The effects of the break were made obvious last weekend, as residents in the area of First Avenue and parts of Ontario Street woke up Sunday morning to flooded conditions. The city spent the week digging several holes to expose parts of the water distribution system to try and track down the breach.
The third attempt uncovered the issue, Warwick said.
After the excavation, crews used what Warwick called a correlator, which connects to two sections of a water main and monitors the sound of the water that goes through that part of the pipe. By using that sound, Warwick said, workers can determine where a leak is.
But, he said, the process isn’t perfect.
“It is very subjective to any bends, any couplings, any joints — a lot of things can throw it off,” Warwick said. “You need exact information to input into it to be accurate, and it's very, very hard to get exact information because we often don't have records of previous repairs in the area, things like that.”
The size of a breach also has an effect, he said, as larger leaks actually make less noise, reducing the instrument’s effectiveness.
“It was difficult to find it.”
Crews are working, first to repair the broken water main and to get affected customers back to full service, Warwick said. The nearby storm sewer lines also need to be repaired, he said, as supportive ground below the surface was washed out from the leak, breaking the pipes.
Once the water main pipe is fixed, the city also has to re-load the main, flush it and conduct water sampling and testing, he added.
Finally, he said, workers can then rebuild the roadway.
There’s no firm timeline by which all the work will be done, he said, but crews are expected to be working into Friday evening and into the weekend.
