A worker at the Gahcho Kué diamond mine under construction northeast of Yellowknife is speaking out about safety concerns, saying water lines to a dormitory's fire suppression system were disconnected.

CBC News agreed to conceal the worker's identity out of his fear of being fired.

He said the problems are at the temporary dormitories on the site.

"They have developed a very nice permanent camp. I hear that's nice," he said.

"It's the temporary ones that they brought in — someone said they were from 2007. So, they are a little bit older."

He said two water lines to be used in case of a fire in the temporary dorms were disconnected and management refused to explain why.

"There have been three generators catch fire in the last month and a half... that's why we kind of ask these questions like, 'why are the fire water lines disconnected?'

"They made it clear that if you keep talking then you will be on the next plane out."

Gahcho Kue dorm mold

Mould in the temporary dorms at Gahcho Kue. A spokesperson for De Beers says mould was discovered in September and rectified. (submitted)

He said employees also made complaints about mould in the temporary dorms, but he said there was no action from management.

Tom Ormsby, director of external affairs with De Beers Canada — the operator of Gahcho Kué — says these concerns have already been dealt with.

He said the fire water lines into one of the temporary dorms froze in December but were fixed earlier this week.

"This is just the water suppression line that has frozen," he said.

"The monitoring of any fire potential is still ongoing 24 hours a day. That system has not been disabled at all."

He added that the generator fires were "isolated incidents, isolated away from people, away from anything that was key.

"These were temporary incidents and these pieces are actually being decommissioned because we are moving into the permanent full-time power supply."

He said the mould problem has also been rectified.

"We did have one incident back in September... where mould was identified as part of our regular inspection process, and it was mitigated instantly," Ormsby said.

Ormsby said Gahcho Kué has gone two million work-hours without anyone taking time off for work-related injuries.

"This is one of the safest construction sites in all of Canada," he said.

"We ask the employees, every day when you step out there, look around and make sure everything is the way it's supposed to be, and if not, we want to know about it. And that's how you actually get on top of these situations. Because, as we have discussed, the things brought forward in this list have been dealt with and that's how you stay on top of them."

He encourages workers to submit all concerns to the company's anonymous hotline.

First production at the mine is scheduled for the second half of 2016.