By Thia James

VIDEO/PHOTOS: Water recedes at Little Red River Park, damage to be assessed

Jul 4, 2013 | 6:51 AM

The waters that flooded Little Red River Park just outside of the city centre have started to recede, revealing some of the damage done to the banks and bridges.

A layer of silt covers the grass and gravel where the Little Red River spilled over its natural banks and up into the park. The cracking layer of silt covers paths and roadways in the park and had even left deposits on a small washroom building in the park.

Where the river flooded and flowed with strong currents, the rocks and gravel are now exposed, cleaned of the silt. And where there is now a layer of silt, that’s where the water ponded and stood still.

At one point the water in the park was a few feet deep. The sheer volume of water that flooded the park came from the North Saskatchewan River, but the soil erosion around the riverbanks was caused by the Little Red River’s overflowing and the force of the flow.

Community services director Greg Zeeben said the silt line that’s evident in the grass is where the North Saskatchewan River just backed up to.

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“So, with 2,600 cubic metres per second flow rate, we had over the long weekend here, you can see where it’s deposited water in the grass areas and things like that. That water has now receded. But our main problem is the erosion that’s being created by the Spruce River itself. And that’s where we’re going to continue to see those high flow levels and we just ask people to stay away because it is a very dangerous site due to the erosion.”

Zeeben said the tree roots are trying to hold the banks together. But at some points, parts of the bank could fall off into the river at any given time.

“The banks are all getting compromised by the erosion that is occurring underneath the bank and underneath the vegetation. So the banks can slough off in as much as 20 foot pieces. So that’s why we want everybody to stay out of the park.”

He said if someone falls into the current, there’s all kinds of unseen debris in the water that would make it near impossible for someone to recover from falling in.

“We just continue to ask people to stay out of the park until we can give a go-ahead as to when the park is safe,” Zeeben said. “We don’t anticipate that that’s going to be anytime soon. There still is high water levels in Anglin Lake and in the north, and that water still has to come through, and those flows are going to continue to erode the banks here in Little Red River Park.”

The Little Red River’s flooding has been caused by the release of water from a dam to relieve pressure on Anglin Lake after heavy rainfall accumulation. The Water Security Agency opened the dam and issued flood advisories for areas downstream from the lake.

The hope is that the area doesn’t experience any more heavy rainfalls that could push river levels – and flow – higher.

But it’s not just the riverbanks that have been damaged by the flooding.

A few of the bridges have had their abutments damaged by the high-flowing water. The Concrete Arch – or ‘Hands’ – Bridge, Sports Council Bridge, and the Swinging Bridge appear to have fared well during the flooding.

But the Lion’s Bridge, and the main road bridge west of the Cosmo Lodge have abutment issues. That’s because the material from the abutments is being washed into the river from underneath the bridge structure, Zeeben said.

The main road bridge, a traffic bridge, the rapidly flowing water is pulling the material from out of the abutments into the river, causing cracks on either side of the bridge.

Some of the concrete adjacent to the bridge has caved in, creating what looks like sinkholes where road should be.

“The water has been moving quickly now for about two weeks, and what it does, is, the scour line has gone down, so in other words, the level of the river bottom has lowered from all the current and it got below the last boards that hold the abutments in place and now it’s pulling the material out from underneath.”

However, he said the bridge structure itself seems to be fine. The city will need to work on the roadway abutments, and Zeeben said they’ll have to dig out around the abutments, since there’s evidence of stress cracks on the roadway itself that make it evident that other things could have happened below the bridge.

He said there are some areas where the city will have to pull off some of the foot bridges. Almost all of the abutments on the foot bridges have been compromised in one way or another, he said.

As well, waters didn’t quite reach the Hesco barrier surrounding the Cosmo Lodge. It missed it by at least a foot. But the waters did come close, and the city hopes to have the Lodge open to the public soon.

Before the city re-opens the park, it will most likely wait until the flow stops and then it will assess the park. After the city has finished assessing the park, it’ll go over how it will be able to open the park, Zeeben said.

He said when the North Saskatchewan River backed up, it filled the washrooms at the front of the park. SaskPower will also have to come into the park and assess the damage done to their power lines. The power had to be cut to an area surrounding a pole that is hanging at a precarious angle.

“And we’re going to have to come up with a good operational, logistical plan in dealing with how we’re going to make the park safe and useable.”

The kind of soil damage done in the park could be unprecedented.

“I cannot recollect where flow rates have done this much erosion. Now, we’ve had high flow rates for going on the third year and I think finally the vegetation and the things that used to hold our banks together have finally released and we’re seeing just, you know, the outcome of many continuous seasons of high flow rates in Little Red or in the Spruce River.”

The city hasn’t begun to put a price tag on the damage done – it’ll wait until the water goes down and it has seen what needs to be done to clean up and make repairs in the park.

“We know that there’ll be a lot of bank restoration that’s going to be required, because the banks have widen themselves out so much, we know that when the water level goes down, and the flow rate lessens, it’s going to return to its old channel, unless there’s some new channels that have been cut, and at that point in time, we’ll be able to figure out exactly what we’re up against, and then we’ll put some costs against it.”

tjames@panow.com

On Twitter: @thiajames