Landslide in Saguenay: the slope will be softened

Landslide in Saguenay: the slope will be softened

BETTING À DAY

After informing the evacuees, Saguenay Mayor Julie Dufour and an MTQ engineer met with the press to explain the nature of the work that will consist of softening the slope where the landslide took place.  

Ms. Dufour first said she regretted all the outlandish theories circulating on social media about the causes of the landslide. 

She then mentioned that as of today (Wednesday ), a government employee will be working full-time on the issue of financial compensation to citizens. 

Clarifications

Denis Demers, from the Movements section from the MTQ, explained that landslides in Quebec are quite common.

“There are 200 reports a year that we assess. In 60% of cases, landslides occur in the spring. The majority occur along waterways. It's exceptional to have such a big slide in these conditions here,” he explained. 

On April 11, a crack was reported to the City when there was there was snow on the grounds. After other interventions and initial evacuations, the MTQ recommended on April 26 a security perimeter and the installation of concrete blocks. 

“It is certain that a slide was preparing, says Mr. Demers. But usually we have time to intervene before they happen. It can happen the next day, but it can also take months or years. The Englobe firm did not even have time to complete its soil study.” 

“There would have been deaths if the temporary measures had not been taken. The wall has done its job. It stopped the debris, the house tipped over due to the speed,” he added.

The causes

< p>Heavy spring rains are responsible for the slide from the crack according to the expert. But as for the crack itself, he blames the nature of the ground, an unstable clay, combined with the heavy amount of snow received. 

There would be no human factors here, “factors responsible for 40 to 50% of landslides”, he takes care to add, inviting people not to do work at the top, in or at the foot of a slope without authorization. 

Aggravation

“But now, with bare and steep ground, it is certain that other landslides will occur”, he is convinced. 

It is the possibility “of a flow very rapid clay that occurs without warning”, which led to the evacuation of 53 additional residences on June 18 and the construction of two dikes the following day. 

He pictures this phenomenon where “the liquid on top makes the top crumble and creates a lot of energy” with the consistency of “an apple that you bite into compared to one that you pass through a blender.

>

“The chances of a clay flow are very low. It happens once every two years in Quebec. But there was no chance to take, even if it came with a host of inconveniences,” says Denis Demers. 

Without the dikes, a clay flow could have come out of the perimeter.  

Looking at the past

Surveys showing an ancient landslide northeast of the mountain “dating between 1,000 and 2,000 years ago” inspired engineers to determine the scale of the task at hand. 

Four houses (five in counting the one that slipped) will certainly be demolished at the top of the embankment. If it is necessary to expand the softening area, two more at the top could be destroyed. 

Two houses at the bottom of the slope – which will be in a safe zone once the work is completed – could be demolished if they were too damaged by the landslide. 

Clarifying that the soil studies are not yet completed, that it remains to know “the quantity of soil to remove around the scar”, Mr. Demers indicated that “we know what to do, it is not complicated, but not yet how to do it.”&nbsp ;

Security

It excludes filling at the bottom of the slope. “It would be too dangerous for the workers.” This indicates that unfortunately the evacuees will not be able to return to their homes before the end of the work. 

Since certain steps are not within his purview and the study is not complete, Mr. Demers cannot give a precise timeline. But he estimates the work phase at around eight weeks “once the shovels are up”. 8m high and to put back vegetation. 

And what about the safety of the occupants who will return to their house? 

“In my work, we always say to ourselves “would we sleep in this house”. And after the work, I would even be ready to buy one of these houses”, he guaranteed. 

Do you have a scoop to send us?

Do you have any information to share with us about this story?

Do you have a scoop that our readers might be interested in?

Email us at or call us directly at 1 800-63SCOOP.