New W.W. Ashley Park dry storm pond system exceeded expectations Monday

The new dry storm pond in W.W. Ashley District performed exceptionally well when approximately 65 millimetres of rain fell (Aden Bowman Collegiate rain gauge) during the afternoon of Monday, June 20, 2022. The pond, which was completed last fall, was designed to handle a 1-in-10-year rain event but accommodated a storm closer to a 1-in-25-year rain event, preventing water damage to approximately 37 neighbourhood homes that typically experience flooding during intense rainfall.

“Flash flooding, especially in neighbourhoods developed prior to storm water infrastructure standard improvements in 1989, can be devastating which is why we have been working to protect as many people and properties as we can through our Flood Control Strategy,” says Angela Gardiner, General Manager of Utilities and Environment. “Monday’s rain was an ideal test. We are very impressed as we have not received any reports of flooded homes adjacent to the new pond and the infrastructure handled more water than anticipated. The pond had completely drained by 8 o’clock that evening.”

Dry storm ponds hold water that would otherwise cause nearby flooding during intense rainfalls. The water flows into storm drains and through pipes into the dry storm pond, then slowly drains into the storm sewer before it drains into the South Saskatchewan River. Whenever dry, it is used as park space. When it fills with storm water, it is deep and dangerous, and residents should stay away.

The W.W. Ashley Park Dry Storm Pond will open to the public this fall after the landscaping has fully rooted. Residents are asked to stay out of the enclosed area until then.

Construction on a dry storm pond in Churchill Park is underway right now and will be completed later this year. Plans are in the works for a dry storm pond in Weaver Park in 2023 and more flood mitigation projects will be built between 2024 and 2027.

“Once these flood control projects are completed, we anticipate seeing a substantial decrease in the amount of neighbourhood flooding in the top 10 highest risk areas of the city.” says Gardiner.

On Monday, storm water and debris infiltrated the sewer system and ended up at the Wastewater Treatment Plant. As a result, the city’s lift stations were operating at capacity and there was a minor sewage spill into the South Saskatchewan River.

“This is an extremely rare occurrence. Due to the small volume, the sewage quickly diluted, and downstream lab sampling did not detect any harmful impacts. The spill was reported to the Water Security Agency and there was no risk to the public.”

A report on the City’s June 20, 2022 Rain Event Response will be presented to City Council on Monday, June 27, 2022.