When former miner Roy Chavez heard about plans to develop the nation's largest copper mine near Superior, Ariz., he thought it might be the salvation of the economically struggling town where he'd grown up and served as mayor.

But as he learned more about the proposal to tap an ore body more than 7,000 feet deep with a method known as "block cave" mining, he changed his mind. Now he fears that the project would be environmentally destructive and limit Superior's ability to develop tourism and other industries.

"Mining is the nature of the beast in this area. I support the industry and the livelihood it provides," said Chavez, who comes from a mining family and worked in the Magma Copper mine nearby until it closed in 1996. "But there's a situation here with this project that just doesn't sit well with us."

Resolution Copper Mining, a firm owned by subsidiaries of international mining giants Rio Tinto and BHP Billiton, is seeking a land swap with the federal government that would give it ownership of 2,400 acres in the Tonto National Forest, where the rich mineral vein was discovered a decade ago. In return, Resolution Copper would give the public more than 5,500 acres of land it owns in various parcels around the region.

But the land the company wants to mine includes popular rock-climbing areas and Oak Flat Campground, which President Dwight D. Eisenhower in 1955 designated off-limits to mining. Native American tribes consider much of the area sacred, and they worry about earth caving in and damaging landmarks such as Apache Leap, where warriors are said to have jumped to their deaths rather than surrender to Arizona soldiers. The proposed mining area is also home to at least one federally listed endangered species, the Arizona hedgehog cactus.

Resolution Copper says the mine would become the country's largest source of copper - supplying half a billion tons a year and meeting a fifth of national demand for 50 years. It would also employ 1,400 people on-site during peak operations, for an estimated total economic impact of $46.4 billion during its 66-year lifetime, according to the company.

To secure the land swap, Arizona Sens. John McCain (R) and Jon Kyl (R) introduced legislation in 2009. Senate Majority Leader Harry M. Reid (D-Nev.) added authorization of the deal to the America's Great Outdoors Act of 2010, an omnibus lands bill that was pulled in late December in the face of Republican opposition. While McCain's 2009 bill would have basically ensured the land transfer, Reid's would have authorized the land swap with final approval contingent on the environmental assessment process mandated by the National Environmental Policy Act and approval from the secretary of the interior.

Jon Cherry, Resolution Copper vice president for legal, external and environmental affairs, said the company is confident legislation similar to Reid's bill will pass in 2011. Along with McCain and Kyl, Rep.-elect Paul Gosar (R-Ariz.) supports the project and recently toured the mine site.

'This is a mining town'



Superior Mayor Michael Hing said the mine would make a "night and day" difference for the town that he's watched shrink to less than half its former size - currently about 3,200 residents - since the Magma mine closed. Hing's grandfather came to the area from China in the 1920s to start small businesses serving miners.

"We've been through the ups and downs of the boom times, when strikes happened, when mines shut down," he said. "This has always been our livelihood. This is a mining town. That's why we live here."

But Chavez, who now works as a planning consultant and owns a bar, and other opponents say the mine would destroy the landscape, severely affect tourism and potentially contaminate groundwater. They are particularly concerned about the block-cave method, which involves blasting a space below the ore body and using gravity to harvest the ore. This leaves large empty cavities underground. There are several other block-cave copper mines in the region, 60 miles east of Phoenix, causing the surface to collapse and crack in some areas.

In an e-mail, Cherry said the company is doing studies to ensure that groundwater will not be contaminated and that natural features such as Apache Leap will not be harmed. He said the mine would increase rather than reduce tourism, and that part of the land swap involves the company transferring land ideal for rock climbing to the public.