Highway 97A traffic was rerouted for 25 hours Tuesday and Wednesday as a result of a mudslide just south of Swansea Point.
The highway was closed around 10:30 a.m. Tuesday, March 14, and not reopened until 11:30 a.m. the following day, after roughly 35 cubic metres of debris rolled down the steep slope on the east side of the road and into the concrete catchment wall below.
Steve Sirrett, the Ministry of Transportation and Infrastructure’s associate district manager for Okanagan-Shuswap, said the small slide knocked two concrete blocks from the wall, into the northbound lane, and some other blocks out of alignment.
“That obviously forced the closure of our highway until we had a chance to have our geo-technical engineers assess the situation and determine what the cause might be and make sure it’s safe to… get the workers in there, start cleaning it up and getting the highway back open,” said Sirrett.
With a history of debris slides at this section of highway, a helicopter was used in the assessment to determine if any activity upland might cause further complications.
“In some cases you can do what you need to do from the ground – in most cases I should say,” said Sirrett. “But there are times, especially with this area, knowing it’s got some history, he wanted to fly it and just make sure there wasn’t anything larger going on up top… I don’t have any of the details, but I know when the flight was completed, there wasn’t anything up there of a major concern that would preclude us from getting the highway back open.”
Sirrett said crews worked through the night, removing the top two layers of blocks from the wall, clearing out the debris in behind it and re-installing the blocks.
“For the most part, the wall did it’s job – it kept the majority of the material off the road,” said Sirrett. “A couple of blocks did come off but cleaning out that catchment area behind… increases the amount of material it can hold behind it again.”
The catchment area and wall were constructed in 1993 following multiple mudslides in the area.
In October 1992, the province conducted a million-dollar slope stabilization project to remedy the problem, which had been ongoing for the past 25 years.
On March 30, 1993, two days before the highway was set to reopen on April 1, two more slides occurred nearby.
One of these brought down an estimated 500 cubic metres of debris onto the highway.
The highway reopening continued as planned, and on April 14 the province announced it would construct the catchment area with retaining wall.