During the Manhattan Project, Los Alamos scientists worked to develop the atomic bomb later dropped on the Japanese cities of Hiroshima and Nagasaki.

LOS ALAMOS, N.M. (AP) U.S. Department of Energy contractors are scheduled to start removing contaminated soil left over in northern New Mexico from the Manhattan Project and early atomic Cold War research.

Work is expected to begin on the south-facing slopes of Los Alamos Canyon and is part of an agreement between federal and New Mexico officials, the Los Alamos Monitor reports.

Officials said the contaminated soils will be temporarily stored at Tech Area 21 at Los Alamos National Laboratory and eventually will be shipped to a permanent area once tested.

The work will include five sites in a 1-acre area. About 125 cu. yds. (95.6 cu m) of soil is scheduled to be moved. One site contains arsenic and the other four contain plutonium, officials said.

“We're cleaning up to residential level, which is the most conservative level,” Los Alamos National Laboratory spokesman Peter Hyde said. “Now that we're in there, we want to do these cleanups and be done. We don't want to go back in there under more stringent requirements and clean up again.”

The Los Alamos Canyon cleanup is one of many included in a consent order signed last month between the New Mexico Environment Department and the U.S. Department of Energy.

The settlement agreement governs the cleanup process of legacy waste for projects going all the way back to the Manhattan Project.

During the Manhattan Project, Los Alamos scientists worked to develop the atomic bomb later dropped on the Japanese cities of Hiroshima and Nagasaki. The program also involved facilities in Oak Ridge, Tenn., and Hanford, Wash.

Some American Indian tribes near Los Alamos have long complained about contamination related to decades of bomb-making and nuclear research.

New Mexico regulators identified as a priority a plume of chromium contamination near San Ildefonso Pueblo, for example.

Groundwater sampling shows increasing chromium concentrations at the edges of the plume, indicating it's migrating through an area considered sacred by the tribe and closer to the Rio Grande, which provides drinking water to communities throughout the region.

The plume has stretched about 1 mi. (1.6 km) into the upper part of the regional aquifer, and is about a half-mile wide and 100 ft. (30.5 m) thick.

San Ildefonso Pueblo, in northern New Mexico's high desert, has a tribal enrollment of about 750.

For more information, visit http://www.lamonitor.com.

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