Revised - The City of Whitehorse is undertaking the replacement of the Takhini sanitary trunk main at an estimated cost of $9 million because of the potential damage a landslide could cause to the line.

City engineer Gareth Earl held a briefing Thursday afternoon to explain the project, the urgency behind it and the road closures that will need to be made.

The $9 million is being provided by the federal gas tax fund, and has been confirmed, he said.

Earl said staff were forced to go with a hastened and shortened tender call in early May but did receive two bids by the closure at the end of May.

One bid was over the budget, but Norcope Enterprises did submit a compliant bid, and was awarded the work, he said.

In June 2022, a tension crack was discovered behind the Takhini softball complex off Range Road, similar to others noted along the escarpment that were associated with landslides in 2022.

“The city is concerned the tension crack could lead to a landslide that would either pull down the sanitary main with it or cause the manhole to tip over and separate from the main, resulting in an uncontrolled release,” Earl explained.

The Takhini trunk main includes flows from Copper Ridge and Takhini.

The main moves between 40 and 50 per cent of the city’s total sewage at an average of 150 to 200 litres per second.

Pipes converge into one behind the softball complex.

The sanitary trunk includes a combination of 400- to 600-millimetre steel pipe installed in 1975.

The installation of 1.2 kilometres of new pipe begins this month along the west side of Mountainview Drive.

Reduced speed limits will be posted.

Sewage will continue to flow through the existing pipe until the new pipe is connected in October.

Beginning this month and running into August and September, Range Road north of University Drive will be closed.

In September and October, Range Road south of University Drive will be closed up to the parking lot of Takhini Elementary School.

Earl said access to Takhini Elementary will be maintained along the south end of Range Road.

Residents from the Northland mobile home park who want to access the school, for instance, will have to drive down Mountainview Drive, cross over to Two Mile Hill and drive back up to Range Road.

Through to September, the northern end of the Trans-Canada Trail will be closed between Mountainview Drive and Range Road.

Range Road closures, Earl explained, will allow continued access to University Drive and the softball complex from the north or the south – though Softball Yukon will have no access to the softball complex for a few days in mid-September to the end of September.

Earl said people can expect to see reduced speeds along Mountainview Drive until the end of this month.

There will be transit delays on routes five and 402. Only route five will serve the university during Range Road closures.

Earl said there will be potential changes to the school buses schedule, and operator Standard Bus Yukon is in discussions with the territorial government regarding those potential changes.

People can expect to encounter increased traffic on Range Road, Mountainview Drive, Copper Road, Industrial Road and Two Mile Hill, depending on the closure phase, Earl cautioned.

There will be a gravel surface and dusty conditions on Range Road until asphalt resurfacing is complete in the summer of 2024, he said.

Earl said the city is in discussions with stakeholders, such as Standard Bus, the university and the Yukon Arts Centre, and has launched its Engage Whitehorse site.

There will be also be public service announcements for the project and bus schedule changes, he said.