Work is getting underway this week to repair a sinkhole that's developed at the Waterfront Flag Plaza at the end of London Road.
The area has been cordoned off by a fence since the discovery in April of this year.
GM of Engineering David Jackson said the sinkhole was initially a 1.2 metre storm sewer outlet to the St. Clair River that was built in 1974.
He said this week's work will include an exploratory dig to check out the pipe.
"It's a pretty unique situation here," said Jackson. "This section of pipe is underwater, just because it is below the groundwater table. We looked at various options for the repair, trying to block the water off or those kinds of things, but we deemed that too challenging. Luckily, it's not very deep so our plan is to replace it in the wet. They'll actually be installing the pipe underwater. It's not something that we do too often, but we think this one should be pretty straightforward."
Jackson said the pipe replacement is planned for early November and should last a couple of weeks.
About 20 linear metres need to be replaced on the land side of the retaining wall.
No “in water” work is expected in the Sarnia Bay but the work may impact pedestrian traffic and access to the nearby parking lot.
The cost of the repair is not known at this time.