Hwy. 407 embankment failure partly blamed for 'devastating' flood impacting Burlington, Ont., homes: mayor

A partially collapsed Highway 407 embankment is at least partly to blame for the "absolutely devastating" flooding of nearby homes in Burlington, Ont., says the mayor. 

Marianne Meed Ward told reporters Wednesday that the embankment collapsed and blocked a culvert, backing up the wastewater system. Then, with the significant rainfall Monday and Tuesday, water overflowed and poured into neighbouring properties.

Conservation Halton says the area received around 80 millimetres of rain overall on Tuesday.  

Christina Basil, a vice-president with 407 ETR — a toll highway that runs through the Greater Toronto Area — said it was "too early" to determine what exactly caused the flooding beyond the large amount of rain. 

On Cavendish Drive, where Meed Ward said the worst of the city's flooding occurred, about 20 locals gathered to speak with city officials ahead of a news conference.

Part of the hilly, winding street was blocked to traffic and while the water was now gone from the road, the street remained caked in mud. 

Pools of water could be seen on a stretch of land between the neighbourhood and the highway, and at least one home with a sloped driveway had a flooded garage. 

Resident Dana Belliveau said her family's home flooded from the basement. Their belongings floated out into their the backyard where the water was so high that it was pouring over their retaining wall. 

WATCH | A 407 embankment failed during heavy rains, official says:  

There was a 407 embankment failure during floods, Burlington official says

4 months ago

Duration 0:53

Rico Scalera, acting public works commissioner for the city of Burlington, says a 407 embankment failed during the heavy rains that lead to flooding on Tuesday July 16, 2024.

"I want to say how sorry I am you are in this situation," Meed Ward told residents. "My first priority is to find out what happened here and to ensure it never happens again to anyone in our city." 

At least 280 properties experienced flooding across the city, Meed Ward said. 

The city will review its infrastructure to see where it needs to be improved, said Rico Scalera, acting public works commissioner.

Along with the 407 embankment's failure, there was other debris that were blocking culverts, although they're designed to hold the amount of water that fell Tuesday, Scalera said. 

Toronto was also hit hard by the rain on Tuesday, while Hamilton was less impacted. There were 16 reports of basements flooding, 10 reports of private land flooding and eight other reports about missing sewer covers and odour complaints, said Hamilton public works manager Carlyle Khan. The city is not aware of any injuries. 

Hamilton's wastewater systems, for the most part, functioned properly, said Khan. Sewer tanks at the wastewater treatment plant came "very close" to overflowing but the rain stopped in time. 

'We are going to see bigger events in the future': expert

The flood wasn't Burlington's first.

In August 2014, the city experienced a massive flood after two months' worth of rain fell in a single. 

At the height of the storm, much of the city was under water and more than 500 basements were flooded and thousands of homes damaged. 

In the years following, Halton region updated some of its infrastructure including replacing or repairing some sewers and encouraging residents to disconnect their downspouts from the sewer system, says a staff report from 2017. It also created a basement subsidy program for residents looking to flood-proof their basements. 

And in 2015, the City of Burlington increased its budget for stormwater infrastructure by $20 million spread across 10 years, including widening and deepening creeks and culverts, a 2019 staff report says. 

While there have been some infrastructure upgrades, Tuesday's flooding shows it hasn't been enough, said Kathryn Bakos, a Burlington resident and managing director at the University of Waterloo's Intact Centre on Climate Adaptation.

And now is the time to adapt, she said. 

As southern Ontario warms due to climate change, more moisture is absorbed into the atmosphere. When it rains, more water falls in a shorter amount of time, said Bakos. There's also a growing population putting more pressure on the water system. 

"What we saw [Tuesday] — we are going to see bigger events in the future," she said. "And if you live anywhere that it rains, you're at risk of flooding." 

She recommended the city continue widening culverts so they can handle the increased amounts of water.

It also needs to separate its stormwater and sewage systems, which will be "massive overhaul" but one that needs to be made to prevent flooding in the future, Bakos said. 

"There's a lot we can do to reduce the risk."

Basil, the 407 ETR spokesperson, said the highway was designed to "meet or exceed" all of the province's standards including storm water management, but the company will continue to work with the city to find out what happened. 

"We recognize the disruption to Cavendish residents, and as members of the community, we've reached out to displaced residents through their local councillor to offer our assistance," Basil said in her statement.