The Environmental Protection Agency has approved a $53 million plan to clean up the Gilt Edge open-pit gold mine in the Black Hills.

The mine became a Superfund pollution site after Dakota Mining Corp., the parent company of Brohm Mining, went broke in 1999 and abandoned it - sticking taxpayers with the cleanup bill.

The state took over the 260-acre site and confiscated a $6 million Brohm bond, but that was far short of the cleanup costs.

EPA declared the mine a Superfund site in 2000 and is paying 90 percent of the costs.

The site is plagued with acidic-water drainage from a large waste-rock dump. It costs $2 million a year to treat the water.

Victor Ketellapper of the EPA said the new plan to bury mine tailings and reclaim the site will reduce treatment costs, but he said some water treatment will need to go on forever.

Reclamation will begin in 2010 and take up to five years to complete, Ketellapper said.

The open-pit Gilt Edge Mine was opened in 1986 on a 258-acre site about five miles southeast of Deadwood and Lead. Workers heaped gold-bearing rock in large mounds treated with diluted cyanide that dissolved the gold. They collected the gold from the solution, which then was refreshed with cyanide and recycled over the mound to repeat the process.

The waste-rock dump also was created and, according to officials, was the main pollution problem.

When sulfides in the rock at the site are exposed to air and water from rain and snow, they become acidic. The runoff contains naturally existing toxics that contaminate Strawberry and Bear Butte creeks.

The site included three open pits.

Frontier miners worked the site as early as 1876, when gold was first discovered in the Black Hills.