Two “large” slides that occurred over the weekend have prompted evacuation orders for three at-risk properties along the escarpment, according to the latest update from the City of Whitehorse.
Mayor Laura Cabott told reporters during a May 30 news conference that two of the homes were unoccupied at the time.
One of the large slides occurred overnight May 27 between Wood Street and Jarvis Street behind a fenced-off area where a smaller slide had previously taken place.
The other large slide, which occurred May 28 around 10:40 a.m. at Jeckell Street, was caught on video by the Yukon Geological Survey that has been shared hundreds of times on social media.
The camera had only been set up above the slope looking down by Jeff Bond, the survey’s head of surficial geology, and his colleague on Friday morning based on their predictions of where the land was not going to hold.
“What you see on the video is the actual earth flow or the landslide happening,” Bond said.
In the video, Bond explained, the surface layer on the slope can be seen giving away “in a wave of material” due to being super saturated from the groundwater flow.
By noon on Saturday, the City of Whitehorse had activated its emergency operation centre to respond. That response involves working closely and collaboratively with the Yukon government’s emergency measures organization and experts in the areas of geotechnical engineering, geology and hydrology, as well as with groundwater specialists.
Since then, the city has expanded the perimeter of closed areas and issued extra signage to advise residents to stay out of the closed areas.
“I can’t emphasize that enough,” said Mayor Laura Cabott.
“Most people respect that – they understand the danger – but it’s absolutely important that people stay out of the closed areas because you are putting yourself in danger as well as anyone that has to come and rescue you.”
On the evening of May 28, city staff went door-to-door sharing information about the recent slides and how to be prepared in the case of an emergency.
“I can say at this point that there are no [additional] buildings or homes that are in danger,” Cabott said.
“We’re continuing to monitor that.”
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The city had previously shut down Cliffside Park, located at Sixth Avenue between Jeckell and Taylor streets, last year due to instability of the slope above the park. The park remains closed while that playground is relocated to another area.
Cabott explained the slides are being triggered by the significant high level of water, previously in the form of snow, that has saturated the ground.
Construction in the area as a result of previous slides did not contribute to additional slides, she said, although the latest slides have caused a delay in the work underway to re-open Robert Service Way. The main artery to downtown has been off limits since the initial escarpment slide on April 30.
Crews will return to the site to continue working on May 31.
Tracy Allen, the city’s director of operations, said the city hopes to open the road in a controlled traffic situation within the next two weeks, depending on weather and groundwater activity over the next few weeks.
Allen predicted the area could withstand some sprinkled showers, while torrential downpour would “definitely not be helpful.”
The latest two large slides are each estimated to be approximately 3,000 to 4,000 cubic metres, which in each case amounts to more land displaced than the initial slide a month ago.
“People can expect — can anticipate — that there will be more activity, very likely more slides and sloughing,” Cabott said.
“That’s why the perimeter is still up. That’s why we’ve moved it out a little bit, as we learn a little bit more with each slide and the saturation level in the water.”
Cabott said the current financial toll to deal with the “the here and the now” is approximately half-a-million dollars.
“It will eventually become quite costly for us to deal with this on a more permanent solution, so that will come later,” Cabott said.
The city continues to watch the “whole escarpment” and is keeping an eye on areas showing tension cracks using drones and visual inspections.
People are being asked to report any slipping and sliding to the city. They are being reminded to call 911 in the case of emergencies.