IDAHO FALLS, Idaho - Crews have begun excavating Cold War-era weapons waste from a second burial site at the U.S. Department of Energy's Radioactive Waste Management Complex is in the eastern Idaho desert.

Cleanup work at the facility, located within the 890-square mile Idaho National Laboratory, began in 2005. So far, the recovery project has focused on excavating radioactive and hazardous wastes, repackaging the materials, then shipping them in trucks for permanent disposal at the Waste Isolation Pilot Plant in New Mexico.

The majority of the waste material came from the former Rocky Flats nuclear weapons plant near Denver. From the 1950s through 1970, the waste material was shipped in drums to Idaho and buried in a 97-acre section of the INL facility, said Amy Lientz, spokeswoman for the Idaho Cleanup Project.

For the past two years, workers have concentrated on wastes buried in a pit about 20-feet below the desert surface.

Earlier this month, crews expanded the recovery to a second pit nearby, she said.

The materials in both pits contain some of the highest accumulation of plutonium and other volatile organic compounds, which pose the greatest threat to the underlying Snake River Plain Aquifer, a Lake Erie-sized reservoir nearly 600-feet beneath the burial sites.

"We're not quite finished with the first burial pit, but we have enough resources and plans in place to begin doing retrievals from both areas right now," Lientz told the Associated Press on Monday. "It'll at least be another year before we can say we're close to being finished."

The materials are a mix of plutonium-contaminated filters, graphite molds used to form weapons, contaminated sludges and oxidized uranium.

So far, more than 7,500 cubic yards of material have been exhumed, classified and repackaged into more than 2,800 55-gallon drums and shipped to New Mexico, Lientz said.