Robert Service Way will remain closed for at least another three weeks as the city prepares to build a sheet pile wall as a temporary measure to make sure another landslide doesn't cross the thoroughfare, city officials said Thursday.
"[Building the wall] will give us some risk-reduction measures to allow us to get in there and remove the debris and shortly after that, open the road to the public," said Michael Abbott, the city's acting manager of engineering services.
Abbott said the sheet pile wall is made by connecting corrugated steel sheets together and driving them into the ground at a ratio of three metres for every metre of material above ground.
It will be about 100 metres wide and cost about $450,000, he said.
The wall will offer a temporary solution until this time next year, giving the city enough time to develop a permanent solution, said Abbott.
The city is considering soil berms with additional reinforcement netting, concrete blocks, or a combination of the two that could incorporate the sheet pile wall as a permanent solution, Abbott said.
'Area is incredibly unstable'
On April 30, a landslide saw an estimated 3,000 to 4,000 cubic metres of sand, silt and clay fall from the escarpment across Robert Service Way, the Millennium Trail and into the Yukon River.
Robert Service Way, one of two thoroughfares into downtown Whitehorse, has been closed from the traffic circle on 4th Avenue to the Robert Service Campground ever since.
City officials said they can't clean up the debris now because there is still too much soil moisture, which caused the landslide in the first place.
Mayor Laura Cabott said the city was acting based on the advice it received from engineers within the City of Whitehorse and from consultants who specialize in landslides.
The city's director of operations, Tracy Allen, said the soil continues to move in the slide area, anywhere from 60 mm to more than 130 mm since the slide happened.
She said while it may not sound like much, it is significant.
"What it's indicating is that there's still a lot of issues, a lot of water pressure and there's still the high risk that [the escarpment] could shear away into another failure," she said.
Allen added there are still some tension cracks forming above the area where the slide took place.
"[That's] also an indication the area is incredibly unstable and it could go any time," she said.
Typically, she explained, similar areas don't settle down until all of the snow has melted, the groundwater has dissipated and things have dried out.
That's why the city is looking at a temporary solution to allow them to open the road to residents as soon as it is safe to do so, she said.
Abbott said the city is also hoping to clean up the debris in the river, but added it could be tricky because of the melting ice and the likelihood of the water level rising soon.
"We're going to do the best we can to remove the debris without further disturbing the bed of the river," he said.