Richard Gleeson
Northern News Services

NNSL (Feb 17/99) - Though there's no question arsenic trioxide is a deadly substance, no one really knows the nature of the threat posed by the 200,000 tonnes stored at Giant Mine.

One thing is certain, taxpayers and not Royal Oak Mines are paying to find out.

In a Feb. 5 letter to the NWT Water Board, Royal Oak reported it was unable to develop a plan for the permanent storage and disposal of the arsenic trioxide by Oct. 1, 1999. The deadline is a condition of Giant's water licence.

"With the ongoing (cash flow) crisis it will be impossible for Royal Oak, on its own, to complete the project as laid out under...the water licence," informed Royal Oak.

The letter also says the company has applied to the Department of Indian Affairs and Northern Development for a grant to develop the plan, known as the Arsenic Trioxide Management Project.

DIAND has already been doing work required of Royal Oak. In late January of last year it commissioned Fracflow Consultants Inc. to study groundwater flow. A more comprehensive study is now in the works.

"We have a company going in there now to get a better handle on these numbers," said DIAND spokesperson Dave Nutter.

The main numbers Nutter is referring to deal with the unlikley prospect of the mines being flooded, something the preliminary studies have indicated will take five to seven years if the pumps that have been removing water from the mine were shut off.

"More importantly, what we're trying to find out is if the arsenic stopes were flooded, at what rate would arsenic be picked up out of the stopes by groundwater and transported to Great Slave Lake," said Nutter. "In other words, what is the real effect? Because we have no idea of just how quickly arsenic might be transmitted and how much of a risk it is."

The water table in the area, normally at the level of Baker Creek, is artificially depressed by pumping water from the lowest reaches of the mine. Royal Oak estimates it pumped 573,396 cubic metres of groundwater out of the mine last year, enough to fill the Ruth Inch Pool 862 times.

Not all the water is going where it's supposed to. Royal Oak is now building what it has agreed will be its last arsenic storage vault.

According to a submission to the water board, things are not going well. Groundwater keeps seeping into cracks in the vault. When the cracks have been grouted, the water table rises. Water is also getting into the chamber next to it, which contains arsenic trioxide.

According to a report by Golder Associates, both the new and old chambers are acting as "sinks" for groundwater in the area.

Seepage into the vault drains into a sump beneath it, explained Nutter. From there, it is treated and pumped out.

"The one thing that makes us breathe a little bit easier is that we feel that even if everything was turned off it would be a number of years (before the mine floods)," said Nutter. "Since we have no intention of turning the pumps off, we feel that over the long term, maintaining the pumps is a viable and acceptable means of keeping the arsenic from entering the environment."