Crews are getting ready to dive to the base of N.W.T.'s Deh Cho Bridge to finally find out whether there's a hole in one of the footings.

Kevin McLeod, director of highways with the Department of Transportation, says there's discrepancies as to whether a section in one of the footings of the bridge piers was filled in back in 2008. The oval area is thought to be about a metre by a metre, and half a metre deep.

Now contractors are going to remove rock to find out if the defect still exists.

"They're going to uncover it," he said. "They're going to give us a video camera of it. They're going to confirm all the details and they're going to wait for our go-ahead."

McLeod says if there is a defect, crews will fill in the area with concrete that can be poured underwater.

The work will cost about $175,000. It is being paid for through securities guaranteed by the New Brunswick government. The province backed the bridge's original contractor, Atcon Construction for $13.3 million, before the company went into receivership.

Initially, McLeod said the territory expected to need about $4 million. Now he says most, if not all, of the money will be used to repair defects and unfinished work.

This summer, crews are also replacing scour rock around the bridge piers because of problems with the original material.

"It's too high in places and too low in other places so it needs to be spread out and the rock that Atcon had put in there is not quite the right rock and we're replacing that with harder and more jagged rock that locks itself in a bit," said McLeod.

hi-deh-cho-bridge-dec-2012-mcmillan

N.W.T.'s Deh Cho Bridge opened in 2012. This summer, divers will inspect the footings of the bridge piers to find out whether there's a defect. (Elizabeth McMillan/CBC)

The rock is there to protect the structure from the Mackenzie River's ice and currents.

Crews have also been installing new extensions on the guard rails to increase the height to 1.6 metres. McLeod says all the remaining work on the bridge should be done by the fall.