The City of Whitehorse has settled on a permanent solution to the problem of landslides closing Robert Service Way, but its construction is many months away. In the meantime, city officials say they recognize the frustration road closures have caused but recognized there will likely be more in the future.
“As everybody’s noted, over the past week, we’d have been back and forth with closures. And while it’s currently open, we know that conditions can change at a moment’s notice. So we don’t know if we have to close it again. This is frustrating. And I really want to emphasize that it’s frustrating for all of us, for residents, tourists, visitors, even our staff,” Mayor Laura Cabott said at a June 7 press conference convened to offer an update on road and escarpment conditions.
Cabott described the road closures as a last resort for the city but that periodic closures are a new reality that will persist until a permanent solution is in place.
The mayor said some progress has been made towards that permanent mitigation plan for the landslide threat as the city has approved the broad strokes of a plan to realign the north end of Robert Service Way, moving the road away from the foot of the escarpment. The plan would also see the regrading of the escarpment and the extension of the sheet pile wall that has been in place further south since last year. Cabott said the city has already entered into a $50,000 contract for conceptual design on the project. City engineering manager Taylor Eshpeter said that conceptual design could be finished by the end of July but that detailed design for the project couldn’t commence until 2024 at the earliest.
Eshpeter said among the other options considered for the long-term mitigation by the city was a geo grid mesh to stabilize the surface of the slope but this was rejected based on future maintenance and replacement expenses.
The conceptual design will offer a better sense of what the project will cost but Cabott said whatever the final number is, it will be a massive undertaking for the city. To offset this, Whitehorse plans an application to the federal government’s disaster mitigation and adaptation fund.
As the June 4 closure of the road that persisted through the following day was unexpected for motorists and trail users, city officials showed some of the data from the slope scanner monitoring a wide area of the escarpment that prompted the closure.
Eshpeter showed visual representations of the scans made of the escarpment with the areas the earth was shifting represented by dark reds and purples while areas that did not shift were in light green. He explained that movement was detected in the early morning hours of June 4 and by noon the rate of movement had accelerated from 40 millimetres per day to 100 mm per day.
Along with what was detected by the slope scanner, Eshpeter said unknowns including the weather played a part in the decision to close the road. He said the kind of rain that was forecast for early this week creates variables that the city can’t react quickly enough to, prompting the closure before the storm hit.
He showed images from the scanner demonstrating significant movement after the rain hit even though it didn’t fall as heavily after the forecast predicted it might.
An additional slide took place on the morning of June 8 but it was contained by the berm and did not reach the road. Because of this and ongoing inspections and slope scanner data, the city kept the road open.
Once the freshet and melt has concluded, the city still intends to remove the temporary berms and jersey barriers constructed this year allowing traffic to flow in a pattern more similar to the one seen before this year’s landslides.
Contact Jim Elliot at firstname.lastname@example.org