Province unveils flood proof plan

CALGARY — A “very large storm sewer” under Calgary and a lengthy diversion ditch near High River are key components of a flood-proofing plan proposed to prevent a repeat of June’s disaster.

The Alberta government will make a decision “as soon as possible” on the proposal from its flood mitigation panel that could cost up to $830 million, says the official in charge of the province’s flood reconstruction.

But Andre Corbould said the province must evaluate both the potential impact and technical feasibility of the plan made public Friday at Alberta’s flood mitigation conference.

“Our job now … is to take those ideas and concepts and turn them into hard engineering that we can then put in front of the government for decisions,” said Corbould, chief assistant deputy minister of the province’s flood recovery task force.

In an interview, Corbould noted the government also has a score of other proposals from municipalities for infrastructure projects aimed at preventing and minimizing future floods.

But the flood mitigation panel’s recommendations are the first indication since the disaster of how the government may deal with future inundations.

Richard Lindseth, a member of the government’s three-person mitigation panel, told the symposium a package of five berms and two water diversion projects on the Elbow and Highwood river systems could be completed in two to three years.

“We think that this is a crucial part — but not the only part — of an Alberta flood mitigation system,” the Calgary architect said in his presentation. “It’s achievable and it’s achievable in an expedited time frame.”

The panel — chaired by veteran energy executive Allan Markin — recommends the province build two dry pond detention berms at the mountain headwaters of the Elbow River and one at the headwaters of the Highwood River. Two more should also be built in the foothills on the Highwood and Sheep rivers.

The dry berms are dam-like structures overtop a conduit in a stream. They are intended to maintain the regular stream flow, while allowing for water to be stored during heavy rainfall or snowmelt.

The total cost of the berms would be between $370 million and $430 million.

Lindseth said the government should also construct two water diversion projects at a cost between $290 million and $400 million that will “provide the extra margin of safety that we feel should be inherent in any system we propose.”

The panel says High River should have an overland bypass similar to Manitoba’s Red River Floodway.

The Calgary diversion project, in contrast, would essentially be “a very large storm sewer,” said Lindseth.

A conduit would travel underground from the western end of the Glenmore reservoir in alignment with 58th Avenue, bypassing the Elbow River valley and depositing the water in the Bow River.

Lindseth said the panel’s priority was the Elbow/ Highwood corridor, but it is now turning its attention to potential mitigation projects on the Bow River.

Premier Alison Redford — who kicked off the symposium but left before Lindseth’s presentation — said it was too soon to say how much the government will ultimately spend on mitigation measures, but dams and berms will be built.