Dozens of people came out Tuesday night in Yellowknife to voice their fears about Giant Mine.
Many expressed their anxiety over the government’s cleanup plan, which is to freeze the thousands of tonnes or arsenic dust underground forever.
"The health of this community, the health of this land, that's at stake, and it's at stake forever," said Lois Little, a Back Bay resident.
She said the federal government is only looking at a short-term solution.
"We might just get this cleaned up, the thermosyphons in, the water treatment plant working or not working, then 10 years down the road, everyone throws up their hands and walks away from it," she said.
Little wants the arsenic removed so it's not a threat hanging over the community.
"The only solution is to keep on working toward a management-free, safe alternative, and that means neutralizing the arsenic."
Peter Redvers said there are no guarantees that future governments will maintain the site.
"How do you solve this problem as opposed to tuck it underground and hope that 100 years from now, someone else will take responsibility for looking after it," he asked.
Redvers said people need more assurance that the water pumped off the mine into Yellowknife Bay will be clean.
Gerry Cheezie worries about his grandchildren, who play on the lakeshore in Ndilo.
"I ain't a scientist and I ain't an engineer, I'm just a common citizen that lives in the community and is faced with the worry of what might happen," he said.
Cheezie said he has a hard time trusting the government’s cleanup plan.
"It's a constant reminder to me of the government’s lax attitudes toward industrial development in the North. So, when they say they're going to clean something up, I want to believe them. But I have difficultly believing them."
The Mackenzie Valley Environmental Impact Review Board will decide this fall whether to approve the federal government’s cleanup plan, and whether to make any recommendations.
Residents are urging the board not to leave them and future generations with questions of "what if?".
Expert says flooding of site is inevitable
An expert reviewing the Giant Mine cleanup said eventually, the mine will flood and the government needs to be prepared.
Franco Oboni is a risk-assessment expert from Italy examining the project for the review board.
At the public hearings Tuesday, he showed a video taken close to a coal mine in Australia in 2010. It showed water from a creek overflowing into a mine pit and within seconds, filling the massive pit.
"I would like you to give us a detailed understanding of the consequences of such a flooding in the pit at Giant Mine, when it will occur. Because it will occur of course," he said.
Oboni said he wants to know the impact that will have on nearby tailings ponds if Baker Creek floods, like they did last year.
Some groups who have been following the cleanup say it will impact not only the immediate area around the mine, but all of Great Slave Lake.
They want to know how ice thickness will be affected by treated mine water which will be discharged into Back Bay.
"They say there is going to be local ice thining — how much, where, is it on the shoulder seasons? Is it going to be safe? They can't really answer question, that's a fundamental thing in terms of public safety. It's hard to believe that after four years into the environmental assessment they can't answer that question," said resident Kevin O'Reilly.
Government officials said the water in the bay will be safe enough for recreation, wildlife and to be used as a drinking source.