Epcor releases maps showing flood risk by sub-basin

Epcor releases maps showing flood risk by sub-basin
Epcor lays out priorities in flood prevention plan
The sub-basin where the Rossdale neighbourhood of Edmonton is located is identified by Epcor as the highest risk of flooding. Rossdale is shown from the 29th floor of Manulife Place in downtown Edmonton. Tom Braid / Postmedia, file

Three of Edmonton’s eight hospitals and urgent care facilities are in areas at a “high risk” for flooding, according to a report that delves into the city’s risk of floods due to extreme weather.

But Epcor officials say they’re optimistic that some of the areas identified in flood risk maps published Friday could be fixed with solutions that may not be costly or complicated — and that a citywide flood mitigation plan could take less time and cost less than the $2.3 billion projected in 2017.

“Three-quarters of the city is in the two lowest risk categories, and so, for prioritization, it’s not just about the sequence that we go in, but that focusing of investment into the highest priority areas,” said Martin Kennedy, Epcor’s director of public and government affairs.

The report, prepared as part of a flood risk mitigation strategy that will be presented to city council’s utility committee next Thursday, delves into what areas of the city are most at risk of flooding, and makes recommendations for what the city ought to prioritize for protection.

To come up with the risk assessment maps, the city was carved into 1,300 storm sub-basins, and risk was assessed for each area by compiling engineering studies, stormwater and climate models, insurance maps, as well as historical flooding and maintenance records. According to Epcor, a sub-basin is the combination of stormwater pipes and depressions in the ground where stormwater collects.

The report presents council with three “scenarios” that weigh different types of risk differently, but Epcor will recommend the option that relied on public engagement.

In that scenario, the sub-basin where Rossdale sits is identified on the map as the highest risk of flooding. But a big part of the reason for that is actually the presence of Epcor’s water treatment plant, said Susan Ancel, Epcor’s director of stormwater strategies.

“The solution to it, though, is that we’re just looking at raising some motors up above the flood plain, so it’s probably not going to be a very expensive solution for Rossdale,” Ancel said.

Because the facility is also home to gas and electrical substations, it elevates the risk level because protecting essential services like power and water, along with hospitals, fire and police, was deemed a priority in a process that involved a weighted survey of 1,500 Edmontonians, which also found citizens want to protect human life and services for vulnerable populations.

If a hospital — or any property — is in a high risk sub-basin, the property it sits on specifically may be all right, Ancel said. If it’s not, there’s still a chance that a feature that increases its level of risk — such as an underground parkade — could be dealt with through something as simple as installing a hump at the entrance that would block water flowing down.

Ward 10 Coun. Michael Walters, who sits on the utility committee, said the report is “much better” than anticipated but said that when committee digs into the report on Thursday, he wants to be “triple-sure” the optimism is warranted.

Ward 8 Coun. Ben Henderson, also on the committee, said he was surprised by how “contained” the higher risk areas are, though a number of them are concentrated in his ward on the southeast side of the river.

“This is something we’ve known was coming for a while. It does feel like we’re getting a handle on it, so we can actually start moving forward on it and not just sit here and worry about it,” he said in a phone interview Friday.

In the meantime, Epcor officials hope homeowners take flood prevention into their own hands, and is offering homeowners free flood protection inspections, and, for those who qualify, a rebate of up to $800 toward the cost of installing a backwater valve. More information about the program can be found on Epcor’s website.

Epcor says it has completed a plan to mitigate flooding in Edmonton neighbourhoods based on results from a survey conducted this summer.

Epcor favours a scenario it says reflects the priorities highlighted by Edmontonians in the survey.

"The most critical things that they want to protect are social infrastructures. So things like hospitals, police, critical utilities and so forth," said Steve Stanley, senior vice-president of commercial services.

The second priority for the 1,500 respondents is ensuring the health and safety of people, and ensuring social services can still be accessed.

Epcor's framework for reducing flood risk divided the city in 1,300 sub-basins. Each sub-basin includes local storm water pipes, and the areas where water collects. 

"We're going to focus on those that have a high risk of flooding. We think that by doing that we'll get the most bang for our dollar," Stanley said. 

Once Epcor receives the green light from the city, it will start breaking down the cost estimates for different mitigation strategies and how those costs will be reflected in utility rates. 

In the meantime, Epcor is urging Edmontonians to reduce the risk of flooding on their own properties. 

Homeowners need to have proper flood insurance, Stanley said, and should maintain good drainage on their property.

"Become educated on what needs to be done. We have a lot of information out there on things like drainage and so forth," he said. 

Epcor also offers a rebate of up to $800 for qualifying homeowners that want to install a backwater valve.

A backwater valve can help prevent sewage from backing up into a basement during a storm. Homes built before 1989 typically don't have one.

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