Whitehorse landslides need multi-million-dollar 'mega project' to fix, mayor says

The mayor of Whitehorse says she's concerned about more landslides along the escarpment by Robert Service Way, after a slide on Saturday closed the road.

Parts of the road will stay closed for now, with barricades in place, as well as along the Millennium Trail and the escarpment trail, and Mayor Laura Cabott said the city has been advised that it's dangerous for people to be in certain areas.

"We're very concerned about that. And it's not just along Robert Service Way," Cabott said Tuesday morning.

"We've been advised by the engineers that are looking at [the escarpment] that there are more tension cracks and there's movement along the escarpment right now."

The slide is similar to one that happened last summer, which spilled across the whole road and caused Robert Service Way to close for weeks. Unlike that incident, Saturday's slide sent dry rocks and rubble across one lane.

It was closer to the city than last year's slide and thus didn't get caught by the retaining wall that was built last year.

Cabott said there's a possibility of putting in more retaining walls, but they're meant to be temporary.

"It's not going to get us out of this problem for the long-term future," she said. "A longer-term solution is what the city requires at this point."

That will require a "mega project," likely costing tens of millions of dollars, Cabott said later in a news conference Tuesday. 

She said the city is talking with the territorial government, as well as the federal government and engineers to determine what's needed. But it's too early to tell what could keep the road safe from future slides, or how such a project could be funded.

"Going forward, it is a very hefty price tag, which the city cannot take on on its own," Cabott told reporters.

That would be on top of a $10 million dollar project to replace the Takhini sanitary trunk line, which carries nearly half the city's raw sewage to the Marwell lift station. A tension crack on the escarpment puts it at risk.

"If we don't deal with that, the slides are gonna take it out," Cabott said. "And then we're gonna have a huge mess."

Jeff Bond, who is with the Yukon Geological Survey, said Yukoners should expect to see more landslides this year.

The latest slide comes just weeks after he warned that landslide season was approaching.

"We didn't have quite as much snowfall as the year before, but it was still quite high," he said over the weekend.

"We had plenty of areas that were kind of set up for failure last year that didn't fail, and so, you know, you have to anticipate that there's going to be more activity."

Saturday's landslide wasn't prompted as much by meltwater as last year's slide, he noted — and it didn't come as a surprise, since the city's engineer consultants had been keeping a close eye on that area.

He said the steep parts of the escarpment are the areas they need to monitor.

"The entire slope isn't an issue — there's certain zones that are potentially problematic. This was a good example of one of those zones, where you have a little bit of accumulation of sediment sort of hung up on the slope," he said.

City engineer Taylor Eshpeter told reporters Tuesday that this weekend's landslide was smaller than those seen last spring. He said larger slides last year included a range of 3,000 to 5,000 cubic metres of material. Taylor said there's no thorough estimation from this weekend yet, but he guesses about 500 cubic metres of soil slid Saturday.

No timeline to reopen road

At Tuesday's news conference, Cabott said the Robert Service Highway will remain closed indefinitely. 

"There are new tension cracks that have been identified and the slope continues to show signs of instability," she said. 

Cabott said crews will continue to assess the slope to see when the road could reopen. That might require an intermittent or partial reopening at first, she said, but drivers should prepare for "significant disruptions" this spring. She urged people to respect closures for their own safety.

Parts of the Millennium Trail and the trail along the upper escarpment also remain closed.

Alternative routes are already in place for buses affected by the slide. Cabott said the city is considering offering temporary free transit to ease traffic congestion while the road's closed. That's something the city did after last year's slide.

Whitehorse's acting fire chief Jason Wolski says there's currently no threat to residents living along the base of the cliffs.

"If there is a concern, we will definitely alert people and put plans in place to notify people and, if the need be, evacuate them."