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Water likely culprit of Saskatoon’s latest riverbank slump

Click to play video: 'Rapid slumping along Saskatoon’s riverbank' Rapid slumping along Saskatoon’s riverbank
WATCH ABOVE: Homeowners along a stretch of slumping roadway in Saskatoon should be concerned according to a U of S expert. Joel Senick tells us a large crack has become a crevice in a week and the rapid degeneration could continue because of groundwater – Apr 29, 2016

SASKATOON – Standing feet away from an eye-level blue barricade donning the sign “Danger, Keep Out,” Alec Aitken admitted he would be nervous if he owned a home on this now blocked off Saskatoon roadway.

“My training allows me to identify it for what it is, a rotational slump,” said Aitken, a professor of geography at the University of Saskatchewan, of the large hole in the road that’s behind the barricade.

“If I were people located in this block, yeah I’d be concerned about what’s happening in my front yard.”

Homeowners in the area initially received word from the city that crews were assessing the situation near Saskatchewan Crescent and 16th Street in early April. However over recent days, what was a crack in the road has evolved into a chunk of the street retreating into the ground.

“The displacement is about a meter and that’s happened quite quickly,” said Jeff Jorgenson, the city’s transportation and utilities general manager.

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Jorgenson added that “there’s a good chance that it is going to keep moving,” however he said homeowners in the area shouldn’t panic.

“The risk to the houses would be very low, the slope, the slide area and volume would have to increase exponentially in order for there to be any risks to the houses,” said Jorgenson.

“There would be lots of evidence if there was any movement that would cause us to get concerned about the houses.”

READ MORE: Riverbank slump forces city to close part of Saskatchewan Crescent

Both Jorgenson and Aitken said a steep slope and a high level of groundwater were contributing to the riverbank failure at the site. Officials say they first noticed instability in the area in 2012, but it was below the street on the Meewasin pathway. The path was closed in 2014, after tension cracks were noticed along the area.

A Saskatoon-based engineering firm will present the city with options on how to fix the slope in late May and Jorgenson said he expected construction to begin in the area in the fall.

“We knew that there was a slope slump there of course and we’re confident that we can get it fixed in 2016,” said Jorgenson.

Riverbank slumps “are things that we should anticipate being part of the normal way the river valley works,” said Aitken. He said the rising level of groundwater was compounded by water that naturally runs through the city’s landscape and is discharged into the river.

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“That movement of water, slow as it may be actually is capable of eroding channels beneath the ground level, we call it groundwater piping,” said Aitken.

“Over time that groundwater piping can lead to collapse.”

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