CH2M HILL Plateau Remediation Co. said Monday it hit its goal of removing nearly 200,000 pounds of contaminants from groundwater at the Energy Department’s Hanford Site in fiscal 2016.
CH2M treated 2.1 billion gallons of groundwater at the facility in Washington state that has been contaminated with radionuclides and toxic chemicals left over from plutonium production dating to World War II. The company removed more than 180,000 pounds of this contamination from the site’s groundwater for the 12-month period ended on Sept. 30, CH2M stated in a Monday press release.
CH2M is DOE’s prime contractor for solid waste and groundwater cleanup at the site near Richland, Wash. The company’s 10-year Hanford Site Central Plateau Remediation contract, managed by DOE’s Richland Operations Office, expires on Sept. 30, 2018, and is worth nearly $6 billion.
“Most of our pump-and-treats are performing far better than originally anticipated,” Karen Wiemelt, vice president of groundwater cleanup at CH2M, said in the release.
There are six groundwater treatment sites at Hanford. The public can track their operations via a website maintained by DOE’s Pacific Northwest National Laboratory. Contaminants treated include: carbon tetrachloride; nitrate; technetium-99; trichloroethene; chromium; hexavalent chromium; and iodine-129.
The majority of the contaminants removed from groundwater in fiscal 2016 were nitrates in central Hanford. The capacity of the 200 West Pump and Treat facility’s membrane bioreactors to remove sludge was expanded 20 percent via additional equipment to individual bioreactors. In addition, CHPRC began using a new pipeline between the 200 West and 200 East areas to allow contaminated groundwater from the 200 East Area to be pumped up and transferred to the 200 West Pump and Treat facility. The groundwater beneath the 200 East Area is contaminated with nitrates from the past use of nitric acid to chemically separate plutonium from irradiated fuel. Liquid waste was disposed of in the soil.
The 200 West Pump and Treat facility also began using a new system for removing uranium from contaminated groundwater in the last year. The plant, which opened in 2012, was designed with additional space to expand capacity, including for ion exchange columns to remove uranium from groundwater. Uranium is present in groundwater in both the 200 West and 200 East Areas of central Hanford.
The increased capacity and capability of the central Hanford water treatment facility helped boost the amount of contaminants removed from groundwater in fiscal 2016 by about 15 tons from the previous year. The increase came despite progress by the five pump and treat plants along the Columbia River to remove hexavalent chromium from groundwater before it can reach the river. A combination of removal of contaminated soil, in some places down to groundwater, and increased pump and treat capacity near the river have decreased the size of contaminated plumes of hexavalent chromium. The pump and treat plant near the K Reactors was shut down this summer because concentrations of the contaminant in groundwater there dropped below levels requiring treatment. The plume will be monitored to ensure hexavalent chromium levels do not rebound before a decision is made on whether groundwater treatment is completed there.
