September 25, 2018 by Ryan McKenna, The Canadian Press
HYAS, Sask.—A reeve in eastern Saskatchewan says no geotechnical investigation was performed on a riverbed where a newly built bridge collapsed only hours after opening.
The Dyck Memorial Bridge in the Rural Municipality of Clayton opened to traffic on the morning of Sept. 14. But later that same day, part of the deck collapsed into the Swan River below. No one was injured.
David Elwood, a University of Saskatchewan professor specializing in geotechnical engineering, said he thinks it’s strange tests weren’t done before the bridge was built to determine what sub-surface conditions were like.
Conducting boreholes tests would have given an indication of where the foundation should stop, how deep a contractor needs to drill and how much steel should be used for the piles.
“It’s very odd to me that one would not want to know where their piles are being pounded into,” Elwood said.
But Reeve Duane Hicks said he has checked with as many as five other engineering companies and they said they don’t do geotech investigations on these types of projects.
Hicks said he was told by the other companies that bid on the project that they wouldn’t have done anything differently than the contractor that built the bridge.
“They would have done exactly what these guys did,” Hicks said Sept. 24. “So they probably would have had the very same problem.”
The builder, Can-Struct Systems Inc., has hired an independent firm to perform tests. Greg Anderson, a bridge inspector with Can-Struct, did not respond to requests for comment.
The municipality has been told it won’t be on the hook for the cost of repairs. Clayton paid about $340,000 for the project.
Elwood estimates that a geotechnical investigation would have cost an additional $20,000 to $30,000. He said it’s possible to get away without drilling boreholes, but there may be additional costs with driving piles until they stop.
He’s not sure whether the soil was strong enough to hold the steel in place and it needed to be dug deeper.
“As a practising engineer, I would never design an in-water bridge pier without having a borehole,” Elwood said.
Bob MacDonald, executive director with the Association of Professional Engineers and Geoscientists of Saskatchewan, wouldn’t confirm whether an investigation is underway.
Most of the debris has been pulled from the river and the piles have started to be put up again, Hicks said.
He said both he and Can-Struct still don’t know what went wrong.
“I don’t care what they do as long as they make it right,” Hicks said.
“I want to be able to drive over that bridge and not have to worry about it.”