HELENA, Mont. (AP) — A Canadian company that wants to restart a gold and silver mine northwest of Helena has hired a company to install a water treatment system at the flooded facility.

Toronto-based RX Exploration Inc. wants to reopen the Drumlummon Mine, which once was one of the West's largest underground mines but was last worked in the 1950s.

CDM Inc. of Helena will design and install a water system to extract arsenic from the estimated 100 million gallons of water that flooded the mine years ago.

Joe Bardswich, chief mining engineer for RX Exploration, said the $328,000 contract is a milestone toward reopening the 120-year-old mine, but said things are not proceeding as quickly as the company had hoped. He said it needs to raise money to complete work on a shaft.

Randy Huffsmith, a CDM engineer, said the company will install two tanks in a large underground room and pump water through the first tank filled with a type of iron media for cleaning, then through a second tank as a backup.

The water will then be moved through a buried, perforated pipe to drain into the ground. Installation of the pipe is nearly complete, and CDM expects the water treatment plant to be operational by Nov. 10.

"The water starts out pretty clean, although it has some arsenic in it, and it will be similar or better water quality when it's released than what's already in the (Silver Creek) stream," Huffsmith said.

The water has flooded to the 400-foot level of the mine, and initial plans are to drop it to the 620-foot level so miners can gain access to the existing 500- and 600-foot levels and conduct sampling and mapping.

Warren McCullough with the state Department of Environmental Quality says RX Exploration will monitor nearby residential wells to ensure they aren't being affected by the pumping. If RX's operation causes a loss of water supply and fails to replace it, DEQ can suspend the company's exploration license.

The company believes it could find more than 70,000 ounces of gold and 1.9 million ounces of silver in 155,000 tons of rock at the mine. On Wednesday, gold was about $944 per ounce while silver was $14 an ounce.