The Yukon Water Board is raising concerns about a potential spike in arsenic levels in underground water.

The issue came up at board hearings into a California company’s plan to mine magnetite from the tailings at the old Whitehorse Copper Mine.

“It's a pretty simple process actually. We pick up the tailings, add water to produce a slurry, then we run that slurry over magnetic drums. The magnetic particles, which are the magnetite, get attracted to the drum and the other particles get washed away. So now we've separated the magnetite from all the rest of the tailings. The rest of the tailings goes back into the hole that we took it out of basically,” said Chuck Eaton, the president of Eagle Industrial Minerals.

Chuck Eaton, the president of Eagle Industrial Minerals, wants to use the magnetite his company extracts from the old tailings, and sell it to Asia where they will use it to make steel. (CBC)

Eaton wants to sell the magnetite to Asia, where it is used to make steel.

Part of Eagle's plan involves moving waste rock from what are called Valleys A and B into something called the Old Pond.

Right now, A and B do not leak any metals, but the Old Pond does.

The Yukon Water Board's technical advisor, Cord Hamilton, wants to know if that has implications for increased arsenic leakage.

"Now we're going to take the tailings from A and B Valley and reprocess them in Old Pond and stack them back up there. What should we expect for arsenic going forward, seeing that we've continued to release arsenic over 40 years? What's going to happen now," Hamilton asked.

Scott Davidson, of Access Consulting a consultant for the company, told the hearing the Eagle will be re-working the surface of Old Pond to ensure water runs off and doesn't work its way through the tailings.

He said any arsenic leaching should not be much different than what is happening now, which is within safe levels for drinking water.

The proposed project would last for 12 years, and then the company’s goal would be to re-vegetate the area.

The old mine has been shut down for the past 30 years – all that is currently left of it is 20 tonnes of waste rock, an old pit and the tailings ponds, which Eagle Industrial Minerals wants to mine.