Washington Closure Hanford and the Department of Energy have met a legal deadline to have most of the waste sites near Hanford's F Reactor cleaned up, including digging up carcasses of animals used for radiation exposure research.

"The 100 F Area is almost finished," said Rod Lobos, an environmental engineer with the Environmental Protection Agency, the regulator for the work. "We're very happy with the progress."

F Reactor operated from 1945 to 1965 as one of nine Hanford reactors to produce plutonium for the nation's nuclear weapons program. Also near F Reactor was a laboratory and an animal farm used through the early years of the Cold War for research on radiation exposure on plants and animals.

DOE had a Tri-Party Agreement deadline to finish cleaning up 53 waste sites, including nine large burial grounds, at F Reactor by the end of 2008. That included digging up contaminated soil and debris, filling holes with clean soil and planting vegetation.

Since the deadline was set, a few more contaminated areas have been found that have yet to be addressed.

But by far the worst of the work has been completed, including digging up 40,000 tons of carcasses, manure and other waste from burial trenches at the former experimental animal farms.

From all the waste sites, workers dug up more than 408,000 tons of waste. They also uncovered 300 bottles of laboratory waste, with some containing a petroleum byproduct used in radiological analyses to determine the radionuclide contained in samples.

The waste sites also yielded seven pieces of highly radioactive fuel that came from F Reactor.

Workers use long-handled tools to try to identify and remove items with unusual radiation readings. If they were suspected to be irradiated fuel, they were placed in temporary bunkers made of concrete blocks. The corroded pieces were cleaned, measured and weighed to determine their identity.

The burial grounds near the Columbia River also yielded a wide range of debris. That included hand carts, reactor hardware, a drill press and gas cylinders, most of them unpressurized.

The largest item found was a railcar in the area used for waste disposal from the experimental animal farms. Cleanup there was completed a year ago.

Animal experiments started at Hanford during World War II, when plutonium was produced for the atomic bomb dropped on Nagasaki, Japan. Some experiments were planned to learn more about the health effects of radiation to protect nuclear workers, and some were for military knowledge.

About 1,000 animals at a time were kept at the farm. They ranged from rodents to cats and dogs to farm animals, including cows, sheep, goats and pigs. In addition, the farm had alligators, although no carcasses were found, and rattlesnakes.

About 95 percent of the waste dug up from the animal farm trenches was manure, some in plastic bags, and radiation checks found quite a bit of it was contaminated with radioactive strontium 90.

Animal carcasses, some packed into a railcar, and sawdust in bags and boxes also were recovered from the trenches. Only minimal radioactive contamination was found in the carcasses.

Work to clean up the waste sites near F Reactor began in July 2005 under Bechtel Hanford, the DOE contractor that preceded Washington Closure. Washington Closure took over the work in September 2005 and shipped the last container of waste from the cleanup in August 2008. Federal Engineers & Constructors was Washington Closure's subcontractor on the project.

Washington Closure then back-filled more than 450,000 tons of soil and planted 107 acres. Contaminated material, other than the irradiated fuel, was sent to the Environmental Restoration Disposal Facility, a landfill for low-level radioactive waste in central Hanford. The fuel is planned to be sent to a national repository at Yucca Mountain, Nev.

More than half of the waste sites, 429 out of 820 total, now have been cleaned up along the Columbia River at Hanford.

"Cleaning up the waste sites continues to demonstrate progress on cleaning up land along the Columbia River and shrinking the site," Lobos said.

DOE expects to have land along the river cleaned up by 2015, shrinking the contaminated footprint of the nuclear reservation to the land in central Hanford.