Toronto

City of Toronto may install pumping station in flooded Lower Simcoe underpass

While spring flooding in the Lower Simcoe Street underpass has become as seasonal as cherry blossoms — the rising levels of Lake Ontario and increased development are creating a perfect storm that could overwhelm the drainage system there for weeks.

The underpass has been flooded for roughly 2 weeks, which is expected to continue: Toronto Water

A car tries to navigate the flooded Lower Simcoe CN underpass on Monday night. (Chris Dunseith/CBC)

While spring flooding in the Lower Simcoe Street underpass has become as seasonal as cherry blossoms — rising water levels on Lake Ontario and increased development are creating a perfect storm that could overwhelm the drainage system there for weeks.

It's the same underpass that garnered international attention in 2013 as images of a waterlogged Ferrari abandoned to the roadway-turned-waterway circulated around the internet.

And the next year, the city commissioned a report that found the flooding has been a perennial problem since the underpass opened in 2009. It flooded five times between 2010 and 2013.

Ever-rising water

Although the city addressed the issue that swamped the Ferrari — a manhole with missing bolts gushed water into the underpass — Toronto Water's general manager said the larger flaw is that the design can't compete with Mother Nature.

To build the road, the city had to lower the existing sewer pipes in the area, something that made them more vulnerable to filling with lake water in spring and during major storms, Lou Di Gironimo said.

"Lake Ontario is in its high-level cycle right now," he said. "It's the highest we've seen it in many years."

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"A persistent severe thunderstorm" dropped heavy rain over Toronto Wednesday evening, causing some flooding along some major roadways.

When those levels rise, the sewage line closes so that lake water cannot flow up into the siphon and overwhelm the roadway.

But there's a catch — the groundwater from surrounding condo and business parking lots collects in the closed pipe, Di Gironimo, said.

So, instead, it floods the underpass.

The underpass had been designed to withstand the five-year average water levels of Lake Ontario in 2006. But Di Gironimo said the water levels have been consistently higher than that ever since.

Permanent pumping?

Last July, after a particularly bad bout of flooding, Mayor John Tory said the city needed to come up with a long-term solution — and one that could handle severe weather.

On Monday, Tory said staff are reviewing the best options to manage the flooding based on the results of an engineering study conducted in the past year.

The city has been manually pumping out the underpass for the past two weeks. And municipal staff are considering whether to install a permanent pumping station in the underpass.

Pylons block off a flooded section of the underpass. Municipal crews pumped out the northbound lane Monday night and then began on the southbound lane. (Chris Dunseith/CBC)

Water management specialist Jenn Drake told CBC Toronto much of the city's stormwater infrastructure is designed to handle average conditions rather than the extremes — because the latter is much more expensive to build and maintain.

A permanent pumping station, however, would resolve the soggy underpass, the University of Toronto civil engineering professor said.

"It'll be an expensive solution, but it's certainly something that could be constructed over a couple of months after the design has been complete."

With files from Chris Glover

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