After the Storm: Learning from July 8th, 2013

In 1954, Hurricane Hazel transformed Toronto. The scale of the storm’s devastation forced the city, its residents, and leaders to rethink urban development regulations and to significantly invest in infrastructure to prevent a similar disaster. That investment paid off last week.

Hurricane Hazel revealed many of the city’s vulnerabilities. The lack of serious injury, loss of life, or major damage following the record rainfall on July 8th is a testament to the lessons learned, and actions taken after 1954.  Now it’s time to assess some of the lessons we can learn from this storm, so we can be prepared for the next one. Two major areas for improvement became evident last week, our hydro system and our stormwater system.

Our hydro system

The city’s hydro system is vulnerable to major weather events. During last week’s storm, tens of thousands of people had no power for 48 hours. It’s estimated that 300,000 people in the GTA were without power at one point.  The primary reason for the outage was that one of the two hydro supply points in the city, Manby Transformer Station, experienced serious flooding.


Manby and Leaside Transformer Stations are the city’s two supply points
Source: Navigant Consulting Ltd.

Policies and investments should be promoted to build resilience into the hydro system. These can include building another supply point to reduce our dependence and increase the systems flexibility. Chicago, a city of comparable size has five supply points, and Vancouver has nine supply points. I do not think it’s impossible to imagine a scenario, such as an ice storm, where both transfer stations could be compromised.

Another strategy is to produce more power locally in smaller facilities. Markham has built a four-megawatt station, which can serve the Markham-Stouffville regional hospital in case of an outage. The plant is so small the Globe and Mail writes it “looks like an extension of an adjoining parking garage.”

We are also reaching a point where in the next twenty-years when most new buildings could power themselves.  Improving the energy efficiency and adding solar panels means that new buildings could produce more energy than they use. This could add significant resilience to our power grid.

Stormwater Management System

Monday’s storm was an excellent example of having too much water flowing into our sewers and streams. The Don River rose so fast that the GO Transit system had no warning, stranding over a 1,000 people on one commuter train in the Don River Valley.


Water levels at the Don Valley East Branch hydrometric station near Thornhill July 8, 2013
Source: Globe and Mail

As we pave over more of the region we are seeing more flash floods. The July 8th storm was the second this summer that led to a flash flood in the Don Valley. Urban growth is contributing to this. In 1990, 70% of the Don River watershed was impervious. Today it’s closer to 85%. Every year, more water runs into the river instead of into the ground. As a result, the water flows faster and rises higher.

There are many ways to reduce the amount of impervious surfaces and increase the amount of water that can be absorbed by the ground. In Chicago, over 200 laneways have been retrofitted with permeable paving to let water seep into the ground.  New York is building bioswales, essentially large planter buried in the street, to soak up water before it ends up in the sewers.

New York City Bioswale by ChrisHamby

New York City Bioswale
by ChrisHamby

Seattle, echoing the innovations that will allow buildings to produce their own power, is experimenting with removing buildings from the water grid. At one school, the Seattle Times writes:

The classroom toilet composts and treats waste on site rather than flushing it into city sewer pipes. Water washed down sinks doesn’t flow into storm drains but recirculates to a 14-foot high wall filled with plants, which will eventually soak it all up. For now, excess flows through the wall.

Large-scale engineering solutions and strong land use controls significantly reduced the risk of flooding in Toronto region in the 1950s and 1960s. Yet, looking forward our main challenge will be to improve resilience when these systems fail. We don’t need a couple of big solutions; we need thousands of smaller ones. They require building local capacity by educating residents, and training designers, engineers, and tradespeople to deal with water and power in our homes and neighbourhoods.  This will enable us to be better prepared us for the next storm.


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