A little work could go a long ways to reduce the flooding hazard west of town, and avoid having to spend $610,000 on a study.
At Monday’s development and planning meeting, Salmon Arm council received a presentation from representatives of WATER (Wetland Alliance: The Ecological Response) about what can be done to mitigate the flood risk from the Salmon River.
Engineer/geo-scientist Calvin Van Buskirk provided the bulk of the presentation, offering some background related to flooding from the Salmon River and what’s occurred to increase the risk.
“Historically, the biggest flood that we had with the Salmon River was in 1894… We didn’t have a lot of development back then and the Salmon River actually had several channels out…,” said Van Buskirk. “Now, unfortunately, we have one channel and it’s occupied by an undersized bridge and the other channels have more or less been chopped off by 30th.”
Van Buskirk noted how subsequent development in the area, including the current Trans-Canada Highway and 30th Street SW, have “effectively dammed up these old channels until water levels get to a point there they jump over top of their levees.”
“Once they get over their levees, they can’t get back and want to wander off someplace else…”
To address this, Van Buskirk pointed to opportunities the proposed Trans-Canada Highway upgrades will open up with the current section of highway that will be left as frontage road.
“We now have opportunities to add some culverts to that for low water flow to help drain those fields, and… to lower the grade there by maybe 18 inches, 16 inches, even a just a foot – keep it lower than 30th – so that water flows over top of the Trans-Canada Highway when there’s a flood.”
That water would then be diverted between the current TCH and the new alignment and back into the Salmon River.
“That’s a fairly cheap fix compared to a $600,000 flood hazard risk assessment.”
Van Buskirk suggested the Ministry of Transportation and Infrastructure might be able to assist with the costs.
Van Buskirk also advocated for the removal of the current Salmon River Bridge, noting the structure, with its centre pilings, adds to the flood risk and is a liability. He suggested a clear span bridge would be more appropriate if the desire is to extend the frontage road over the river.
Couns. Alan Harrison and Kevin Flynn expressed their gratitude to WATER and Van Buskirk for the cost-saving suggestions.
“My issue with the flood risk or management study: $610,000 with nothing spent on mitigation,” said Flynn.
“And so we were going to spend over half a million dolllars…for someone to tell us where all the issues are, and I think we kind of know where all the issues are, and what you’re saying is here’s an inexpensive way to hopefully resolve those issues, some of it hopefully can be done by the ministry,” he added.
Flynn asked if the work could be phased, with the grading of TCH/frontage road being done before the bridge replacement.
“That would be the first thing to do…,” replied Van Buskirk. “If the bridge triggers a flood or it’s blocked up behind the bridge, you’ve got another outlet for it, that’s great. If you do the bridge and the water goes over the levee, you still don’t have an outlet for that water.”
Mayor Nancy Cooper noted it was suggested a stormwater master plan needs to be done.
“We should be on that probably sooner rather than later so we’ll be talking to staff how we can get that through,” said Cooper.