The trunk line that transports 40 per cent of Whitehorse’s sewage is being rerouted in April to avoid an anticipated landslide.
That temporary bypass will be brought online before the melt, according to Gareth Earl, the city’s associate manager of engineering services. The Takhini subdivision can expect road closures on Range Road and potential diversions toward Yukon University.
Earl outlined the city’s plan at a media briefing on Feb. 21.
The university, Takhini Elementary School, Softball Yukon and the Whitehorse Correctional Centre will experience brief disruptions in April, including a pause in plumbing expected to last about 12 hours. The city will consult before scheduling the tie-in, Earl said.
Residences in Takhini shouldn’t be impacted, unless an “emergency situation” necessitates decreased water consumption, Earl explained.
“We’re working away from that, hopefully. That’s a last resort,” he said.
The temporary pipe precedes a permanent bypass, which will divert the line down a “more gentle slope” along the west side of Mountain View Drive.
The project is slated to cost $10 million and is scheduled for completion this winter. The construction tender closes in April.
The project was pitched to city council last summer, when the tension crack was discovered. At that time, the city’s engineering manager said the 1975-era line would have needed replacing in the next decade to increase capacity, regardless.
The current line, which moves sewage from Takhini and Copper Ridge to the Marwell Lift Station, intersects with a tension crack located just outside the Pepsi Softball Centre in Takhini.
The crack signals that a landslide is “highly probable,” Earl explained. It could pull the main sewer pipe with it, or separate a nearby manhole from the main line, resulting in “uncontrolled release” of sewage flowing at about 200 litres per second. Earl compared the flow rate to the flow of “1,000 kitchen taps left on.”
Once the sewer pipe is out of the way, the city isn’t anticipating major risk to people or property.
The slide will have a “decent run out distance,” according to Earl. It isn’t expected to reach Mountain View Drive, but may cause Trans Canada Trail closures.
Contact Gabrielle Plonka at gabrielle.plonka@yukon-news.com