THUNDER BAY — It will take weeks longer – possibly even months – to repair a damaged 15-foot-wide culvert that carries the waters of McVicar Creek beneath River Street.
The problem came to light on May 5 when a sinkhole developed in the middle of the street, forcing the closure of the road.
City officials initially speculated that it would take a minimum of two weeks to reopen the four-lane artery.
Inspections of the culvert, however, have shown that the repair job will be more complicated than they had hoped.
"We got into the bottom of the culvert to do some surveys. A number of sections of the culvert had failed. The culvert looks like it may have shifted and twisted a bit," city project engineer Mike Vogrig said Monday.
Vogrig explained that "a couple of bottom sections of the culvert curled up, so a lot of soil was sloughing from the side of the culvert and pushing its way out into the stream. Once you lose that pressure of the soil on the side of the culvert, it can move around and roll around."
He said engineers are currently doing structural evaluations of the culvert to get a better idea of the best way to make repairs.
"It's not going to be a short-term closure by any means. There could be a significant amount of work to do to get it back in place."
Engineers are expected to have some options on the table by next week.
One option is to pour a concrete bottom on the culvert while water is diverted through a second, undamaged culvert that's right beside it.
Another repair method could be to line the inside of the culvert with a slightly smaller one before re-compacting the soil.
Studying and pricing these and other options, and finding the materials, will take time, so it's impossible to predict yet when River Street will be reopened.
In the worst-case scenario, Vogrig said, there's potential for the street to remain closed for much of the summer or perhaps even longer.
Engineers will also take a closer look at the second culvert this summer to make sure it's not at risk of developing a similar problem.
