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Town reviews first phase of drainage plans to mitigate future floods

October 9, 2020   ·   0 Comments

New Tecumseth’s flood in July of 2017 left properties and cornfields in several feet of water, leading Town Council to begin developing a plan for future weather-related catastrophes.

Matrix Solutions, a consulting company, was hired to develop a Drainage Master Plan (DMP) and its water resource engineer, Karen Hofbauer, delivered an update to Council last Monday, September 28, covering Phase 1 of the project.

She said the potential cost in damages from significant weather events ranges from $7.5 million for a 5-year storm to $35 million for a 100-year storm, or as much as $380 million for a regional regulatory weather event, comparable to Hurricane Hazel in 1954 or the Timmins Storm in 1961.

“These expenses wouldn’t be incurred through the Town but these would be incurred by property owners and insurance companies,” Hofbauer noted.

“The costs related to the regional flood is quite high. This value is driven by flooding at the Honda plant and associated industrial lands which account for a very high proportion of that regional cost.”

Climate change is an important consideration for flood planning and, in some places, it may result in 100-year floods becoming the new regional regulatory event, said Hofbauer.

Fortunately, this isn’t the case in New Tecumseth and the Town won’t be chasing a moving target due to climate change, since there’s no areas where the 100-year climate change flood is larger than a regulatory weather event.

However, the Town’s rivers and creeks could increase in volume by as much as 33 per cent by the year 2100, according to climate science data.

New Tecumseth’s residential and urban areas are in low-risk locations for flooding with only four to seven per cent impacted during a regional weather event. Instead, farmlands, open spaces and low-lying areas will endure the bulk of flooding.

Mitigation plans outlined in Phase 1 of the DMP included building a culvert by Sir Fredrick Banting Road, north of John W. Taylor Road, which would prevent overflows in the area during a significant storm.

“This location received a high priority ranking due to the frequency of potential flooding as well as the number of [properties] and infrastructure impacted within this urban area,” said Hofbauer.

“It is likely the solution could be identified which could be implemented in a relatively short time frame.”

An area of concern during heavy rainfall events that was brought forward by Town residents is around the intersection of Side Rd. 20 and 5th Line.

Hofbauer told Council construction of a larger culvert along Side Road 20 in the impacted area will help prevent flooding.

Phase 1 of the DMP recommended many other areas of concern that they would like to investigate further.

“Phase 1 was primarily a fact-finding mission of existing conditions related to rivers and flooding. Our analysis was based on the best background information currently available. Updated and refined hydraulic flow data is required to confirm the existing results,” noted Hofbauer.

The Nottawasaga Valley Conservation Authority is currently working on revising this information, which, when complete, Hofbauer will return with refined high-risk areas to analyze further.

Phase 2 and 3 of the DMP will focus on flood risk areas and provide a more detailed analysis so informed decisions can be made with regard to flood planning by Council.

The next two phases of the project will be included in the Town’s 2021 budget and are expected to be complete after two years.

By Sam Odrowski
Local Journalism Initiative Reporter

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