Conceptual designs for long-term flood mitigation at Exshaw and Jura creeks has the MD of Bighorn and ratepayers considering options and prices.
Golder Associates presented five options for Jura, and four options for Exshaw at an open house on Tuesday (Dec. 15). Every option came with a 40 per cent contingency.
“Coming up with a scheme that was affordable and functional that all stakeholders will buy into was necessary,” said Les Sawatsky, Golder senior consultant.
Once the choices are narrowed, preliminary designs are expected to be before MD administration for recommendation early in 2016, with construction on Jura Creek slated for after July 1, 2016. Estimated completion of Jura Creek mitigation work is November 2016.
Construction on Exshaw Creek would follow.
The high and low costs for the Jura Creek options, with a conceptual design for a 350-year event, ranged from $15.5 million to $4.5 million, with a price tag to the MD attached at $4.05 million to $750,000.
Each option design varied, with three focused on controlling water and debris flow from Jura sloping westbound, towards the hamlet of Exshaw. The designs would drain water overflow to the south, towards the Bow River.
The fourth and fifth options – the most and least expensive – tackled the issue right on Jura Creek. A concrete culvert box installed under Highway 1A, with a sediment trap before it, would divert water flow south, instead of rushing west towards the hamlet.
At the high price end, the creek would see a 350-metre channel extension that would be armoured with costly riprap.
For the Exshaw Creek options, with conceptual designs for a 500-year event, they peaked at $18.6 million and bottomed out at $9.5 million, with an estimated cost to the MD of $4.98 million to $2.25 million.
The priciest option would involve the creation of a new eight-metre high dam before flow reached the hamlet and upgrades to the Highway 1A bridge.
Sawatsky said they are currently in talks with Lafarge at Exshaw about receiving gifts in kind to help lower overall costs.
In 2013, the floodwater and debris that smacked Exshaw caused about 75 per cent damage to the hamlet.
MD Reeve Dene Cooper said the municipality will take some time to digest the designs before organizing and requesting funds from the provincial government.
“Golder worked within the scope that was outlined for them and brought to us a number of interesting proposals for each of the creeks, not a solution, but several solutions for each,” Cooper said. “And also a cost bracket, which makes it easier for us to find the dynamic we’re trying to defend against and also the possibilities that are there because not everything we can imagine is not actually possible when it comes to the engineering.”
