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Trans-Canada Highway could fall into Oxford sinkhole 'anytime': engineer

The town of Oxford, N.S. is dotted with sinkholes across a five-kilometre stretch
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The town of Oxford, N.S. is dotted with sinkholes across a five-kilometre stretch.

One of those sinkholes, according to recently discovered images, sits under the Trans-Canada Highway.

"A failure could happen anytime," says Henry El Naggar, a professor of geotechnical engineering in the Department of Civil & Resource Engineering at Dalhousie University.

Aerial images from the 1930s show a sinkhole in the exact spot where Highway 104 was build in the 1960s.

"A sinkhole is a cavity in the ground that opens," explains El Naggar. "Some of the rocks, like limestone, when the water flows they get dissolved. You get erosion, so the sinkhole opens."

The professor tells NEWS 95.7's The Todd Veinotte Show that construction crews were likely aware of the sinkhole when the highway was built, but they didn't have proper solutions at the time.

"At that time they just filled it with rocks, and that's it," he says.

With the opening of another sinkhole in the town of Oxford in 2017, El Naggar is worried the one under the highway could open up too.

"As it's started to open, it's going to continue. But at which rate, this is what we need to know," he says.

The engineer is worried that changing climate could mean faster erosion at the sinkhole.

"We have more cycles of more storms and rain, so I think this will contribute to exercising the rate," he says.

El Naggar says Dalhousie engineers are keen to install monitoring devices near the highway to monitor the erosion.

"I want to study it at the site and we can install some kind of monitoring equipment," he adds.

The professor says there could be multiple solutions to the problem.

"We can bridge the highway in this section, this is one possibility," he says. "We can do some kind of reinforcement from underneath."

The "bridge," El Naggar explains, is actually an underground mesh that prevents more soil from falling into the sinkhole.

"We put a couple layers of it underneath the ground. It's going to provide some reinforcement for the backfill on top of it," he adds.

The most costly option, El Naggar says, would be having to relocate the entire section of highway.

El Naggar says the issue could be resolved within just a few weeks once the province comes up with a plan of action.

"We could concentrate a construction effort so it will be fixed quickly," he explains. Because this is a safety issue, we need to do that."

The Dalhousie professor says his engineering team hopes to get involved in finding a solution.

"You have all the work we need here in Halifax and at Dalhousie University we are very capable of doing this," says El Naggar. "It's my pleasure if they invite me to look at something."

 

With files from The Canadian Press


Victoria  Walton

About the Author: Victoria Walton

Victoria is HalifaxToday.ca's weekend editor and a Halifax-based freelancer. She is originally from Nova Scotia's Annapolis Valley.
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