REMEDIATION OF CHEMICAL AND RADIOACTIVE CONTAMINANTS IN GROUNDWATER ALONG THE COLUMBIA RIVER - HANFORD SITE TECHNOLOGY ADVANCEMENTS

The Hanford nuclear reactor operations and chemical separations processes supported the generation of plutonium for the Cold War and left “problem areas” of contaminated soil and groundwater. Over 440 square kilometers (170 square miles) of groundwater beneath the Hanford Site are contaminated with hazardous and radioactive waste, and almost half is above state and federal drinking water standards. Conventional pump and treat and other baseline technologies are not the permanent solutions for remediating contaminated Hanford soil and groundwater and are to be supplemented or replaced with innovative technology.

One area implementing advanced technologies for contaminated soil and groundwater cleanup is along the Columbia River. In order to protect the Columbia River, immediate cleanup technology solutions are needed for hexavalent chromium, a mobile chemical contaminant; short-lived radionuclide strontium-90 which is highly absorptive, and slow moving; and the very long-lived radionuclides of uranium. Over the last several years, advanced remediation technology demonstrations were conducted for these three contaminants.

Pump and treat actions are being supplemented by an in-situ redox manipulation barrier and in- situ bio stimulation to halt chromium plume migration to the river. An apatite injection barrier is now being tested for removing strontium-90 from groundwater, along with studies conducted to evaluate the application of phytoextraction using coyote willows. Uranium remediation technology includes sequestration technology including polyphosphate addition to bind this contaminant to the soil. This technology is planned to replace the in-effective natural attenuation.

The Washington State Department of Ecology (Ecology) has a role to prevent and cleanup pollution and to support sustainable communities and natural resources. One of our priorities is to stop contamination from going to the Columbia River. Ecology’s near-river shore contamination cleanup expectation is to stop contaminants entering the river by 2016 through the deployment of cost effective, full-scale deployment of innovative and conventional technologies, especially for chromium, strontium-90, and uranium.