Whitehorse hires contractor to remove unstable part of escarpment

The City of Whitehorse is trying to get ahead of another landslide by giving part of the unstable slope a bit of a push.

The plan, announced Monday, is to spend $175,000 to force about 6,000 cubic metres of rock, sand and mud down the escarpment to be trucked away. Local contractor Sidhu Trucking has been hired to do the work which could begin as early as Tuesday.

"Why are we doing this? Again, there's pressure from the public, and from emergency services and what have you, to see if we can open Robert Service Way," said Mayor Laura Cabott at a media briefing on Monday.

"We've done a lot of background work on this, and worked with our experts and we've come up with this plan."

This is the second consecutive year the city has been forced to close Robert Service Way — one of the main arteries into downtown — after a landslide sent debris from the escarpment spilling across the roadway.

The city has so far seen two large slides this spring, and is expecting more in the coming weeks as the weather warms and melting snow further saturates the already-unstable ground.

The plan announced on Monday would deal with one specific area near the earlier slides. City officials say there's a tension crack there indicating that another large slide could happen at any time.

The city doesn't want to wait for the inevitable. Excavators, working from the top of the escarpment, will push the unstable material down and remove it mechanically.

Cabott calls it a temporary solution.

"It's not a fix for the entire escarpment, but we're hoping this will at least be a fix for that area," she said.

The work is expected to take about two weeks, said Taylor Eshpeter, the city's manager of engineering services. Robert Service Way will remain closed in the meantime.

The goal is to remove the unstable material in a more "controlled" way, Eshpeter said. No explosives will be used, and the work is not expected to send more debris onto the roadway. Everything will be done using heavy machinery. 

"We see this as an action we can take right now, and a known risk that we can mitigate against," he said.

"This is just a variable we can eliminate at this time."

Still, officials were unable to say when Robert Service Way might reopen. Even once the excavation work is done there will be risk of further slides elsewhere along the escarpment.

"These are all efforts to get to that ultimate goal [of opening the road]. We do hope that we're there soon. But I think it's fair to say at this point that there will still be mitigative measures in place for any opening," Eshpeter said.

Any slides in the coming weeks may in fact be more significant than the ones already seen this month. Officials characterized those earlier slides as "drier," whereas the risk now is that spring freshet triggers wetter mudslides that travel further and have more impact.

Nevertheless, the risk remains mostly in the area alongside Robert Service Way, officials said. Monitoring work has found some seepage elsewhere, but no real areas of concern in the Takhini area, or Drury Street and the rest of the downtown. 

Monitoring work will increase in the coming days and weeks, Cabott said.

She also urged city residents to stay out of areas that have been closed because of the potential risk.  

"Those of you that aren't, it's dangerous. And if we need to move into some sort of enforcement activity, the city will consider that," she said.

Cabott also said on Monday that the city is still looking at whether to waive bus fees while Robert Service Way is closed, as it did last year. She said the city has asked the Yukon government help cover the cost of making transit free until July 1.