The city was aware of a small leak in a water main near Smyth Road and it was scheduled for repair, but it ruptured Friday night and flooded nearby streets before city crews could get to it.
The water main at Smyth and Botsford Street failed at about 7:30 p.m., sending water up and into streets and lawns for hours.
Water main failures are more common during this time of year once frost begins to set in and moves pipes around, said Jean Cere of the city's Public Works department.
In this case, the city was aware of a small leak in the water main and it was scheduled to be repaired, but it got bigger and caused a rupture before they could get to it, Cere said.
The initial leak was being monitored, but it wasn't deemed severe, he said.
"They knew it was here and it was scheduled for repairs. It was a small leak and our water works branch was coming in to do the repairs. But unfortunately last night the break got bigger, and we're now fixing it," he said.
Residents upset by lack of city crews on scene
After the break, the water wasn't shut off until well after 10 p.m., three hours later.
People in the affected neighbourhood were left wondering why no workers were showing up at the site to deal with the flooding water. Firefighters did show up to make sure basements weren't flooding and to keep an eye on the situation, residents said.
The city says shut-off valves aren't always close to the sites of water main breaks. And in this case, once crews found the appropriate valves, one of them wasn't working, said Dixon Weir, the city's general manager of environmental services.
That meant the crews had to find valves to shut off water to a bigger area.
But Weir said after the 7:30 p.m. water main break, crews had begun assessing the situation at about 8 p.m.
Excavation work at site underway by 11 p.m.
"The city crews did respond quite rapidly," Cere said, adding that there was a smaller crew working Friday night due to the weekend.
Working shut-off valves were found west along Smyth more than two hours later, and city crews were excavating the street at Botsford and Smyth to make repairs by 11 p.m.
"It took them significantly longer time to isolate a wider area," said Coun. Peter Hume. "So as a result, we couldn't get the water turned off until approximately 11 o'clock at night so that they could begin work on the water main break."
Maintenance work to prevent shut-off valves from failing is done once every three years, Weir said, but failures aren't uncommon.
2 other water main breaks reported nearby
The failed water main at Botsford was made of PVC pipe, not the unlined cast-iron pipe found along Smyth, which was installed in 1955.
Though the PVC pipe is newer, it comes apart much like a zipper when it fails, Weir said, sending a lot of water into the street.
Two other water mains failed later Friday night along Smyth Road, and Hume said the failures were a result of shutting off the water supply.
The second happened at about 10:20 p.m. along Smyth, near Edgecombe Street, just one block east of Botsford.
The third happened at midnight along Smyth near Lynda Lane, three blocks west of Botsford.