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Yorkton Council received an update on its West Storm Drainage Study and design project during its regular meeting Monday.

Associated Engineering (EA) has been doing the review, and company representative Jason Horner made Monday's presentation.

"Associated Engineering has evaluated the storm system through the use of a computer model. A key outcome of the modeling exercise is that additional survey is required to verify system evaluations prior to carrying out any upgrades," explained material circulated to Council.

"The model results indicate that the storm sewers in Yorkton have the capacity for a one-in-two year storm event. They likely do not have the capacity for a one-in-five year storm event which is commonly used in the design of storm sewers. When larger storm events occur, flooding is expected in areas where it has previously occurred," said Gord Shaw with the City's Planning & Engineering Department.

Horner said in creating the model they found Yorkton's "storm sewer system was a bit lacking in information," including information on pipe elevations.

So EA undertook a 'skeleton' survey, including an aerial look at the city, and incorporating information from the Assiniboine Watershed Stewardship Association to provide data for a workable computer model.

The model takes in not the underground pipes, but the road system above ground, said Horner,
"It's quite a complex model," he said.

The reason for the dual model is simple, in situations where the underground system cannot handle waterflows, the streets become a secondary option to control where water goes.

Horner said specific solution ideas will now be put into the model to determine the effectiveness of the idea in terms of handling run-off. That will lead to some specific recommendations in April.
Horner did add it would not be a single "silver bullet" solution.

"It will be a series of small things," which will all contribute to handling run-off.

Horner added the finished plan would be geared to having the underground system handle what they termed a one-in-two year rain event, with basins and other above ground work helping handle a one-in-five year event.

For a major one-in-25-year rain event Horner said some flooding and resulting property damage is likely to still occur even after the plan is implemented.

The next phase of this study will look at these areas to create a means to reduce the likelihood of this. This could include storage in storm water ponds, surface re-grading, and/or pipe and ditch upgrading.

"The goal of this next part of the study is to prevent as much as possible, flooding of private property," said Shaw.