Richard Gleeson
Northern News Services

Yellowknife (Mar 01/02) - In a few months, the federal government will make a decision that will affect the Yellowknife area for generations to come.

After more than two years of studying the problem, the government is about to decide what to do with the 237,000 tonnes of highly toxic dust stored in caverns beneath Giant Mine.

"By June we want to be comfortable in selecting a preferred option," said David Nutter, acting head of the group determining what to do with the arsenic trioxide dust, a byproduct of half a century of gold refining at the mine.

The Department of Indian Affairs and Northern Development, which inherited environmental liability for the mine when owner Royal Oak went bankrupt in 1999, intends to present a detailed plan to the Mackenzie Valley Land and Water Board by Oct. 1.

A recurring theme from presenters at an information meeting at the Yellowknife Inn Wednesday night was the need for public support for whatever method DIAND chooses to proceed with.

That support will be key when DIAND proceeds to an environmental review.

Senior technical consultant on the project, Daryl Hockley, said his reading of the regulatory legislation that would apply suggests that it would be nearly impossible to approve a method that is vigorously opposed by the public.

At the very least, significant pubic opposition would result in a longer review.

One person at Wednesday's meeting -- a copy editor at this paper -- suggested a public vote should be used to determine the preferred option.

Two basic choices

The options being considered include variations on two basic approaches -- leaving the water soluble dust in the ground and removing it.

When the range of options was presented last year, there was vocal opposition to leaving the toxic dust where it is and isolating it from the water table by freezing the ground around it.

When that opposition surfaced again on Wednesday night, Nutter suggested it was based on unrealistic expectations.

"It came from Yellowknife, it originated in Yellowknife -- I think Yellowknife has to deal with it" he said, betraying some frustration.

"It's easy to say we shouldn't leave the problem for future generations, but it's going to be here for future generations.

"There's problems for future generations all around us."

DIAND and Steffen Robertson and Kirsten, the international consulting firm Hockley works for, believe whatever option is taken will require perpetual care. Each of the options being considered would require 15 to 20 years to implement.

The pumps used to artificially lower the water table beneath the mine will continue for up to a century.

Variations on the removal option centre on what would be done with the dust once it is removed.

Hockley conceded that one of the three removal options, purifying and selling the arsenic, is becoming increasingly impractical as health concerns about using arsenic as a wood preservative increase.

The other two removal options, stabilizing the dust chemically and stabilizing it in a concrete-like mix, would leave between 700,000 and 1.3 million cubic metres of waste to monitor forever.

Another significant difference between the options is cost. Freezing the ground and leaving the arsenic where it is projected to cost up to $70 million.

Cost estimates for the removal options range from $185 million to $410 million.

Regardless of what is done with the arsenic trioxide once it is removed, the extraction method would be the same.

"Nobody"s come up with a way to get all of this dust out of the ground," Hockley said.

Extraction would begin with boring a hole to the caverns from the surface, mixing water with the dust to create a sludge and pumping the sludge to the surface for treatment. Residual slurry would be removed from underground using remotely operated scoops.

Open pit mining would be used to remove the residual slurry from irregularly shaped caverns, requiring diversion of the Ingraham Trail "by a few hundred metres," according to Hockley.