A highway expansion project in the Okanagan has turned into a major headache.

The province and the federal government are spending $54 million to turn the last remaining 7-kilometre, two lane stretch of Highway 97 between Kelowna and Penticton into four lanes. The problem is the lanes have to be blasted and carved out of a large, rocky hillside.

Since the summer, this has meant intermittent road closures and delays for the approximately 14,000 vehicles which travel the corridor every day.

But now the highway is closed indefinitely, after blasting on Friday caused a 200,000 cubic metre rock face to crack and start slipping down the bluff, creating a serious rock slide risk.

On Tuesday, the province's head geo-technical engineer, Mike Oliver, told reporters that it could be up to a month before the situation is safe enough to open even a single lane of alternating traffic.

“That is not a good scenario, but that is a scenario,” he said. Pressed further, he held out the possibility the rock face could be stabilized as early as this weekend.

An access road is being built to the top of the unstable mass, so machinery can be taken up to start pushing blasted material from the top to the bottom. The idea is to lessen the weight at the top of the mass and reinforce the toe, so as to halt the slide. The unstable mass is currently slipping about 15 milimetres a day.

“In my way of thinking, if we had two days of no movement at all on this bluff and with monitoring, we could establish single lane alternating traffic with spotters,” said Oliver who acknowledged he is worried the plan might not work right away.

And in the long term, all of the material from the unstable mass, or about 20,000 dump truck loads worth, will have to be removed, a process which will take months.

The closure is wreaking havoc. To take other highways around the closure adds over 200 kms and two hours to a one-way commute that's normally 70 kms and one hour long, though the province has made some minor upgrades to a forest service road to provide a gravel detour which takes only an extra hour.

Lots of people find themselves living on one side of the closure, with their workplace on the other, notably employees with the Interior Health Authority and Okanagan College.

The ambulance service has had to put a helicopter on standby to make sure it can get emergency cases around the closure.

And a local company, Glencoe Trucking, figures the detour adds about $250 per truckload of goods moving between Kelowna and Penticton.

Transportation Minister, Kevin Falcon, said this kind of problem on a road building project is unusual.

“We haven't seen anything like this in our ministry for well over 20 years,” he told the Capital News.

Ask if the ministry was concerned the contractor which conducted the blasting, Arthon Contractors Ltd., had done something wrong to cause the problem, Falcon said, “We really don't think so.”

He went on to say Arthon has been doing a good job on the project.

Falcon chalked up the cracked bluff to the inherent challenges of putting roads through the kind of tough terrain typically found in B.C.

“What we believe likely has happened is that there was a natural geologic fault line in that rock and that fault line has been awaked likely due to the work that has been going on on that massive project,” he said. “But even that is partially speculative.

And despite this incident, Falcon is determined to see the expansion completed.

“Obviously that project will continue. It's just a question of figuring out how we best manage this particular issue,” he said.

Adrian Nieoczym reports for the Capital News in Kelowna.