Hanford workers cleaned 145,000 pounds of contaminants from the groundwater beneath the nuclear reservation during the past 12 months, the Department of Energy said Thursday.
The contaminants came from 2.2 billion gallons of groundwater — an amount that would fill enough water trucks lined bumper-to-bumper to stretch from Los Angeles to New York.
The contaminated groundwater was pumped out of the ground and treated at six Hanford plants, with cleaned water reinjected into the ground.
The plants include five along the Columbia River that remove hexavalent chromium. The chemical can cause cancer in humans and is particularly poisonous to young salmon, even in small amounts that meet drinking water standards.
The sixth treatment plant, which is in central Hanford, is larger and more sophisticated. It can remove multiple contaminants from groundwater, including radioactive carbon tetrachloride and uranium.
An expansion of the plant allowed it to remove uranium from contaminated water throughout fiscal 2017.
Because there is a smaller mass of uranium in the groundwater than other contaminants, such as nitrates, contractor CH2M Hill Plateau Remediation Co., treated more water than in fiscal 2016, but removed less contamination by weight.
With half of Hanford’s plants at least five years old, including the central Hanford 200 West Pump and Treat facility, major maintenance has been required to keep them running efficiently.
Some of the groundwater treatment plants along the river had new pumps installed during the past year, increasing treatment capacity at those plants by up to 300 gallons per minute.
Since treatment plants began operating in the mid-’90s, almost 18 billion gallons of contaminated groundwater has been cleaned and returned to the ground, according to DOE.