Pothole-turned-sinkhole a headache for Saanich neighbourhood

What started out as a pothole on a Saanich, B.C.,street during a snowstorm in February has turned into months of geotechnical investigation and likely acostly fix for the Vancouver Island district located immediately north of Victoria.

Over the winter, road crews discovered a sinkhole had formed under Albina Street at Gorge Road, and it was growing.

Steel plates were installed to stabilize Gorge Road, which is a busy thoroughfare, so traffic could keep flowing.A block of the quieter Albina Street has been cordoned off by safety fencing since the the discovery.

Determining the cause of the sinkhole was no easy feat, saidHarley Machielse,the director of engineering for the District of Saanich.But geotechnical experts have zeroed in on a sewer main installed eight metres below the road in the 1950s.

"At the timethey would have used kind of mining technology where they would have excavated a shaft and used timberframing to support it," he said.

"So over time, 70 years has gone by and part of that timber has probably rotted allowing some of the soil above it to migrate down."

The investigation found other sections of the street areslumping above the pipe and repairsare likely needed along an entire block of Albina Street.

Plus, the sewer pipe is still in use, complicating plans to make thoserepairs,Machielse.

"Here we are with something we didn't expect and now we are we are working to find out what are some remediation options are to fix it."

The block of Albina Street affected by the sinkholeis flanked by a shopping plaza, homes and an apartment complex, but there are no public safety risks to any of thestructures,Machielsesaid.

The district is working on a plan to open up access to the shopping plaza parking lot as soon as possible, but full remediation of thesinkhole could take a couple of years, he added.

The cost of repairs has not yet to be determined, but is expected tobe significant. However,the sewer pipe construction that has likely caused the sinkhole is not believed to be widespread in Saanich.

In the meantime, Albina Street remains closed to all traffic. Weight restrictions for vehicles have also been put in place on Gorge Road from Tillicum to Harriet roads in both directions, although transit buses are operating normally in the area.