During the 45 years of plutonium production at Hanford, waste water was being dumped or injected into the ground. We oversee the monitoring and cleanup of contaminated water under the Hanford site.
Today at the 580-square-mile Hanford site, the water under 65 square miles is still contaminated beyond safe drinking water limits. We continue to monitor the groundwater and the treatment activities to limit the amount of contamination entering the Columbia River.
Each year about 1,000 wells around the site are sampled to determine what contaminants exist under the Hanford site and where they have spread. Some of Hanford's contaminated groundwater enters the Columbia River. Because the river is so large, and typically has hundreds of thousands of gallons of water flowing by every second, the contamination that enters the river is diluted to barely detectable levels.
How was the groundwater contaminated?
Hanford's initial nuclear reactors used cold water pumped directly from the Columbia River to cool the nuclear fuel, and then released the contaminated water directly back into the river. In later reactor designs, the waste water was sent to cooling ponds to reduce the amount of radioactive materials entering the river. However, the contaminated water trickled down through the soil and eventually reached the groundwater.
During nuclear arsenal production at Hanford, an estimated 440 billion gallons of waste water was created. It was then dumped or injected into the ground in cribs (covered, open-ground waste filtration beds), pits, trenches, injection wells. Waste water sometimes overflowed as it moved from reactors and processing facilities to tanks or other storage areas.
The primary contaminants of concern include uranium, technetium-99, iodine-129, tritium, carbon tetrachloride, hexavalent chromium, and strontium-90; and nitrate contamination is widespread. While plutonium might be present in a few sites at very low levels, it’s not considered a major contaminant.