Hamilton Kent Blog

Is your municipality ready for its 100-year storm?

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It all starts with a few drops of water falling from the sky.

Drops turn into torrential downpour. Puddles turn into rivers. Public transit systems turn into stationary shelters for commuters. Basements turn into swimming pools.

And manhole covers and underground water infrastructure can’t work out whether water is flowing in, or out.

What started with a few drops is now the storm of the century, also known as the 100-year storm.

What is a 100-year storm?

Despite its name, a 100-year storm can happen more than once in 100 years. The likelihood of one happening in any given year is a 1 in 100 chance, or 1 percent. The data used to determine this is based on historical data taken from precipitation patterns in each separate municipality over a number of years. This means that each municipality will have their own measurement for a 100-year storm.

Due to factors like urbanization, increased infrastructure and climate change, the measurements for what qualifies as a 100-year storm could be changing as well.

Why is it important to prepare?

Currently, many cities in both Canada and the United States are unprepared to handle the impact of a 100-year storm. We’ve spoken before about Chicago’s 500-year storm in 2008 that lead to 11 billion gallons of combined sewer overflow ending up in Lake Michigan.

This is only one example of water going untreated due to a water system reaching capacity. In other examples, a municipality could also end up treating extraneous water due to large amounts of inflow and infiltration.

Increasing dangers leading to increasing costs

Research from both Princeton University and MIT shows that climate change could cause powerful storm surges to occur every three to 20 years.

Another study out of the University of Iowa found that floods are increasing in the northern US, while they’re decreasing in the south. The declines are related to a decrease in ground water in the south; meanwhile in the north, where ground water is more abundant, there is a greater risk of flooding. The reason that these sections of the country are getting more or less rainfall is so far unknown.

In 2016, Canada broke records for the amount of insurable damage caused by natural disasters country-wide. The Insurance Bureau of Canada reported that $4.9 billion of insurable damage was claimed in 2016. Three-billion, seven-hundred thousand of that $4.9 billion is directly related to wildfires in Fort McMurray, while the rest can be attributed to floods in southwest Ontario (where the mayor of Windsor declared a state of emergency) and Atlantic Canada (where manhole covers came off due to water pressure). The increase in insurance claims can also be attributed to 70 percent of Canadians now living in urban areas, where natural disasters leave large numbers of households susceptible to damages.

Why are floods more frequent?

We’ve talked before about the longevity of water infrastructure. Pipes generally last between 50 to 150 years. Pipes installed in the 1800s are thicker than ones installed over the last century—meaning that they will all begin to fail around the same time. Unfortunately, that time is now. Pipes will continue to fail over the next few decades due to age, corrosion, design and installation.

Not only this, but as mentioned above, there is an increase in urbanization in both Canadaand the United States—meaning an increase in grey infrastructure and fewer cases of more permeable green infrastructure.

Essentially, if our infrastructure can’t handle an increase in frequency in 100-year storms, water won’t have anywhere to go, and the number of disruptive and damaging floods will increase.

What can you do?

The Canadian government has already begun to address increases in storms with the National Disaster Mitigation Program (NDMP) created in 2014. The NDMP earmarked more than $200 million over five years to prepare communities and municipalities for future storms.

The 2016 Federal budget also allocated $75 million in new funding to tackle climate change.

In terms of what municipalities can do with this type of funding, watertight solutions will ensure that if a storm does happen more frequently, residents won’t be caught off guard with systems backing up into basements, streets and waterways.

Ensure you’re choosing manhole covers that can lock in place, and watertight joints for pipes, so that if a storm surge leads to flooding, extraneous water doesn’t enter into your sanitary sewer system.