Department of Energy:
Preliminary Information on the Potential for Columbia River Contamination from the Hanford Site
GAO-06-77R, Nov 4, 2005
- Accessible Text:
The Department of Energy's (DOE) Hanford site in southeastern Washington state was established in 1943 to produce nuclear materials, especially plutonium, for the nation's defense. The site occupies 586 square miles northwest of the cities of Richland, Pasco, and Kennewick, with a combined regional population of over 200,000. The Columbia River, the nation's second largest river and a source of hydropower production and drinking water for downstream communities, as well as a major route for salmon migration, flows through the site for almost 50 miles. DOE built nine nuclear reactors to produce plutonium and other materials near the river shore to take advantage of river water for reactor cooling. Several miles away from the river, DOE built other facilities used in making nuclear materials. During operations from 1943 to 1989, activity at these reactors and other facilities generated large volumes of hazardous and radioactive waste. Some of this waste was deposited directly into the ground in trenches, injection wells, or other facilities designed to allow the waste to disperse into the soil. Some of the most hazardous and radioactive material was stored in large underground tanks. Over time, concern has developed about the impact of Hanford's waste moving through the ground and toward the Columbia River. Besides the waste discharged directly into the ground, DOE has assumed, based on tank monitoring data and other techniques to detect contamination in the soil, that 67 of the 177 underground storage tanks have also leaked contaminants into the soil. Many types of hazardous and radioactive waste produced at Hanford can be borne by water through the ground. While Hanford is a near-desert location with limited rainfall and thick layers of soil and rock beneath its surface, water from precipitation and other sources moves through these layers, and the groundwater moves in the general direction of the river. In the center of the site, the groundwater is more than 200 feet below the surface, but at the river, the groundwater is at or near river level. Over time, the movement of these contaminants through the "vadose zone"--the span of soil and rock between the surface and the groundwater beneath--has resulted in a number of contaminant "plumes." These plumes are volumes of contamination extending downward and outward from their sources. When these plumes reach the level of the groundwater, the contamination they contain enters the groundwater. In some cases, contamination from these plumes has already reached the river. Since the early 1990s, DOE has shifted its efforts at the Hanford site from production of nuclear materials to cleaning up the contamination and other materials left over from the production era. Milestones and requirements for this cleanup are specified in an agreement between DOE and its regulators--the U.S. Environmental Protection Agency and the Washington State Department of Ecology. DOE spends about $2 billion per year on the cleanup of the Hanford site and estimates that the cost of Hanford's cleanup effort will eventually total about $45 billion and will be completed around 2035. The cleanup effort includes exhuming and treating buried waste, cleaning up facilities, and other necessary steps, including protecting the Columbia River by keeping contamination from migrating through the groundwater to the river. This report responds to a Congressional request for preliminary information about DOE's efforts to address river contamination. It addresses (1) the past, current, and future sources of contaminants to the Columbia River and the status of the contaminant plumes that threaten the river; and (2) DOE's planned approach to prevent contamination from reaching the Columbia River and DOE's efforts to implement its plan.
Contamination from the Hanford site that may threaten the Columbia River includes (1) contamination that resulted from disposal activities during the era in which DOE produced nuclear material; (2) contamination that could occur during cleanup activities, such as from an accidental spill; and (3) possible future migration of contamination from waste that will be permanently disposed of on the Hanford site in accordance with the cleanup actions DOE and the regulators plan to use. Based on groundwater sampling results, DOE reports that plumes of contamination continue to move through the vadose zone and the groundwater and are leaching into the river. DOE estimates that about 80 square miles of groundwater under the site contain contaminants at or above federal drinking water standards. Because the groundwater and the river are at the same relative elevation, these plumes are leaching directly into about 10 of the nearly 50 miles of river shore on the site. DOE's approach to addressing contaminants in the vadose zone and groundwater that threaten the river is to first address threats from contamination at sites located near the river or requiring immediate action and then to address contamination threats that are farther away from the river's edge. In conjunction with these efforts, DOE has a groundwater monitoring program to better understand the threats. These efforts are carried out by several DOE and contractor organizations. Both the National Academy of Sciences and the DOE Inspector General have issued reports noting concerns about DOE's management of the program.