The U.S. Energy Department said this week that more than 1 million tons of uranium mill tailings have been moved from the banks of the Colorado River near Moab to a disposal cell 30 miles away at Crescent Junction, north of Interstate 70.

The work is part of a $1 billion cleanup of the old Atlas Corp. uranium mill across Highway 191 from the entrance to Arches National Park.

Donald Metzler, DOE project director, said moving the millionth ton is a major milestone.

"Consistently shipping maximum trainloads of 136 containers has definitely helped us hit the 1-million-ton mark," he said, noting that federal stimulus funds has helped pay for about half of the volume moved so far.

The DOE said the volume moved over these first 11 months would be enough to fill 30 floors of the Willis Tower, formerly Sears Tower. The project entails relocating a total of 16 million tons.