Part 5 of 5: Resilient infrastructure

A recently completed dry pond in the neighbourhood of Parkallen in Edmonton is an example of the range of measures that can contribute to stormwater mitigation. supplied — A recently completed dry pond in the neighbourhood of Parkallen in Edmonton is an example of the range of measures that can contribute to stormwater mitigation. **supplied**

A comprehensive – and inclusive – strategy for stormwater mitigation

Intense storms are becoming more frequent due to climate change, and Canadian cities look to innovative solutions for being better prepared. An exploration into stormwater mitigation in Edmonton led to the development of a methodology designed to enhance equitable outcomes without putting undue stress on ratepayers.

Work on the Stormwater Integrated Resource Plan (SIRP) brought together multiple stakeholders, including the City of Edmonton and representatives from the utilities and insurance sectors, says Susan Ancel, director of One Water Planning at EPCOR, a leading provider of clean water and safe, reliable energy. “We started with the premise that climate adaptation has to address environmental, social and economic concerns – that’s why SIRP considers stormwater mitigation from numerous perspectives.”

Since historical models often focus on the financial implications of property damage that are ranked according to property value, Ms. Ancel proposes a different approach “where priorities are assigned in a more equitable way.”

Two scenarios, of a basement versus an underpass flooding, help illustrate the distinction. With limited public funding, which of the two would take priority? And what mitigation measures are appropriate for each example?

“An underpass flooding doesn't necessarily cause physical damage, but it carries a high health and safety risk compared to a flooded basement, which can have a lot of damage but less impact on the health and safety side,” she explains. “Our strategy looks at health and safety, environmental, social and financial risks.”

To gauge Edmontonians’ priorities for mitigation measures, an online survey asked participants to rank priorities for different impact scenarios. “We had 1,500 respondents representing the city’s demographics,” says Ms. Ancel. “Participants agreed that considering financial risks is important, but they rated health, safety and social implications even higher, with key concerns revolving around the impact of potential disruptions to emergency response, health and social services, and water and power.”

To address such a wide range of considerations, SIRP proposes five actions: slow, move, secure, predict and respond. “’Slow’ means capturing stormwater closer to the source, such as through green infrastructure. When that’s not possible, we want to ‘move’ it to a location without impacting properties; for example, stormwater ponds,” Ms. Ancel explains. “The ‘secure’ component is about flood-proofing properties. ‘Predict’ is using smart technologies and monitoring to know where and when a storm is coming, and ‘respond’ is building up our emergency response protocol.”

These five dimensions can make the strategy more cost effective, she says. “For example, traffic control can be considered a more efficient investment for addressing underpass flooding, while a dry pond or green infrastructure would be a fitting intervention for areas where residential properties are at risk.”

Word about the publicly available methodology has spread across Canada: Edmonton recently placed first (tied with Regina and Toronto) on a list of 16 major Canadian cities for limiting the risk of flood mitigation, according to the Intact Centre on Climate Adaptation at the University of Waterloo. And Ms. Ancel was recognized with an individual Canada’s Clean50 award in the cities category for her leadership role in SIRP.

For more stories from this feature, visit globeandmail.com