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Vehicles and pedestrians negotiate the deep water flooding the Lakeshore Rd. at the foot of Reese Street in Toronto, after heavy rains and lightning storms passed through the region.Peter Power/The Globe and Mail

Glenn McGillivray, managing director, Institute for Catastrophic Loss Reduction

The rain that hit the Toronto area Tuesday morning, while heavy at times, was not really anything to write home about. I mean, it was in no way comparable to, say, the 138 millimetres that fell over a 12-hour period (with 102 mm in just two hours) on July 8, 2013. That event triggered over 30,000 insurance claims, totalling more than $1-billion.

Yet, parts of the lower Don Valley Parkway and eastern portions of Lakeshore Road flooded this week – again. Another Tuesday, another flood. And while little if any direct damage was caused by this latest event, the commute was made difficult for many private motorists and commercial drivers, likely leading to at least some economic loss.

Toronto seems to be a place that is beginning to chronically flood, even from what once were fairly benign rainfall events. And as heavy rainfalls are projected to become more common in a warming world and as increased urbanization, under the mantra of densification, continues to plod on, the situation will only worsen in the years ahead.

So what to do? Let’s start by clearing a few things up.

First, when heavy rainfall-related flood events (know technically as pluvial flooding or more colloquially as urban floods) hit Toronto, there are always calls from the peanut gallery blaming the city’s ancient storm sewer system. We almost always hear the same old pearls that the city’s system was designed for storms of the past but can’t handle the extremes that we get today.

The truth is that underground storm sewer systems were never constructed to handle extremes such as the July 2013 storm. These systems were generally built to deal with fairly average, run-of-the mill precipitation events. And while true that some places in Canada, including Toronto, have invested heavily in their underground and overland storm water systems to handle heavier rainfall events, examples of these projects are relatively few and far between. Disaster researchers muse that if we had storm sewers in place to handle extremes, we’d have no money left for schools, hospitals or police.

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Muskoka chairs near the shore of Olympic Island sit partly submerged in water.Fred Lum/The Globe and Mail

There is also a perception, particularly shared by those who have experienced chronic basement flooding, that local governments are doing nothing to address the flooding/storm water management issue.

However, the myth that Toronto and other cities are essentially doing nothing on the storm water/urban flood matter couldn’t be further from the truth.

Toronto, for one, has implemented a master plan for wet weather flow outlining a number of projects to improve storm water management across the city. In its 10-year capital plan (2016-2025), $1.5-billion has been earmarked for such work.

As part of its involvement in the Rockefeller Foundation’s 100 Resilient Cities Initiative, Toronto also formed an expert Flood Resilient Working Group. The Group helped produce a flood resilience charter for the city, released as part of Toronto’s Resilience Strategy. The charter includes strategies such as improved understanding and modelling of urban flood risk throughout the city, integrating flood risk considerations into infrastructure decision making and working to increase public understanding and action to reduce risk.

The city has also implemented a subsidy program to help homeowners fund the disconnection of weeping tiles from the public sewer system and pay for the installation of sewage backwater valves and sump pump systems. This is key, as these programs facilitate actions needed by homeowners that are crucial to solving the basement flood problem.

Toronto also has a proactive basement flood education and communication program, which includes multi-channel print/mass media/online advertisements and social media outreach. Further, the city has also enacted bylaws to make downspout disconnection mandatory and has banned the use of reverse slope driveways in new home construction in the city. These are a design relic from the 1960s and 1970s, which are horrible for bringing water to – not away from – homes.

Toronto is actually one of the leaders in Canada in the area of urban and basement flood risk reduction.

That being said, change will not come overnight, as the city has close to 11,000 kilometres of sanitary and combined sewers, and all work on these and new systems is completely supported by revenues from water bills, with no reliance on the property tax base.

The challenge facing Toronto and, indeed, a long list of other cities in the country, on the storm water and flooding issue is huge. And it will only get bigger as our urban areas join many of their international counterparts in the move toward more compact cities where roofs, asphalt and cement overtake trees, wetlands and grass.

Part of the answer to the dilemma sits not only with so-called grey engineered infrastructure (i.e. pipes, culverts and drains) but also with a mix of other solutions currently being investigated by the city.

Some of these solutions will make big differences, others will be much smaller. But every little bit will help, particularly in older neighbourhoods where huge below-ground pipe solutions are costly, destructive and disruptive.

The alternative? A lot more Tuesdays.

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