THUNDER BAY – Finding worse-than-expected damage, the City of Thunder Bay will need to fully replace a collapsed culvert that’s kept River Street closed for months.
It’s still possible the road will reopen in time for winter, though it wouldn’t be fully repaved by that time, staff reported in an update to city council Monday.
The failure of one side of the twin culvert that carries McVicar Creek beneath the artery caused a large sinkhole to develop on River Street on May 5, following a period of heavy rain and spring flooding.
Engineering staff had expressed hope the collapsed west side of the culvert could be reinforced with a new lining instead of being fully replaced, which would potentially have brought costs as low as $1.6 million.
An inspection on July 26 found the failed pipe had continued to collapse and lost confining pressure, dashing those hopes, engineering staff reported.
Instead, staff recommend replacing the culvert with a new steel multi-plate arch culvert, which is expected to have a lifespan of around 75 years.
The step isn’t estimated to raise costs beyond the $2.5 million already approved by council for the project, but it will extend the construction timeline thanks to expanded excavation and backfilling work, said project engineer Mike Vogrig.
It won’t be possible to complete paving, curb, sidewalk, and guiderail work until 2023, he said, but Vogrig is cautiously optimistic it could be opened as a gravel surface over the winter, possibly topped with cold patch.
“Our big push is to get it done this year, but with the timeline so tight, all it takes is for something to go a little bit sideways and lose a couple of weeks,” he said.
The city plans to pre-purchase materials over the next two weeks, and launch a tender for the work by the end of the month, giving bidders about three weeks to respond.