Mike Bryant
Northern News Services

Yellowknife (Sep 02/05) - As mines go, Giant mine isn't all that deep, but it's underground chambers are as dark as any.

It was hard not to notice for members of the Giant Mine Community Alliance as they took a crash course on spelunking the old mine's cavernous depths last week.

One of the first lessons was to watch your step. Rail car tracks and overhead pipes are just a few of the hazards in the muck-filled tunnels.

The Alliance - a community liaison group set up by the federal government three years ago - was invited to have a look at a few of the mine's arsenic trioxide chambers, which all together hold 237,000 tonnes of the stuff. A single teaspoon-full can kill a person.

Within a couple of years, the federal government plans to begin freezing the arsenic to prevent it from leaching into the water table.

"We've done a lot of work underground just to gain access to these chambers, and of course you'd never see that on the surface," said Bill Mitchell, the federal government's manager of Giant Mine clean-up.

The department of Indian and Northern Affairs plans to cut several drifts of their own underground in order to conduct inspections of the arsenic chambers, plus haul in the equipment needed to freeze them.

A network of distribution tubes filled with coolant will be set up to do the job. Ultimately, the plan is to chill 15 arsenic chambers to about -2 C.

Water in the mine is the main reason why the government wants to freeze the arsenic. It filters down from the surface through cracks in the rock, before it is pumped back up to the top through a pipe nearly two kilometres-long to the water treatment plant.

At the 750-foot level, Alliance members marvelled at a fast-flowing freshet of water pouring from the ceiling to the passage floor.

"We'll still be pumping water for quite a long time," said Mitchell.

"We're not going to let the water flood up to the (chambers) until they're totally frozen. It'll probably take in the order of 10 to 12 years."

Although the arsenic is confined behind concrete bulkheads, small amounts of it still percolates out - forming toxic stalagmites near the bulkhead doors.

Mark Liskowich, Mitchell's right-hand man, pointed to a puddle of greenish water at the foot of bulkhead No. 63. It's sickly colour is likely from some kind of bacteria living it and not the arsenic. It's bad stuff nonetheless.

Don't drink

"You wouldn't want to drink it," he said. "It's probably about 3,000 to 4,000 parts per million of arsenic."

The maximum allowable for residential standards is 160 parts per million.

This fall, the government plans to submit a closure plan to the Mackenzie Valley Land and Water Board. With their approval, the real work of freezing and containing the arsenic will begin.

"It's going to be a lot of work," said Mitchell.