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. Contamination from production era. Contamination at Hanford resulting from plutonium production (which occurred from 1943 to 1989) that is currently migrating to the river is primarily from: Intentional disposal of liquid waste and contaminated water into the ground (about 450 billion gallons). Leaks into the soil from waste tanks and the pipelines that connect them (between 500,000 to 1 million gallons containing about 1,000,000 curies of radioactivity). Contamination that has begun to migrate from solid waste (more than 710,000 cubic meters) disposed of on-site in burial grounds, pits, and other facilities. Chemical and radioactive contamination currently affects more than 180 of the 586 square miles of the site’s groundwater and large areas of the vadose zone. While there are numerous contaminants now in the vadose zone and the groundwater below, DOE believes the key contaminants in the groundwater include hazardous chemicals (such as carbon tetrachloride, chromium, nitrate, and trichloroethane) and radioactive materials (such as iodine-129, strontium-90, technetium-99, tritium, and uranium). These contaminants are of concern because of their extent, their mobility in the groundwater, and the potential health risks associated with them—at sufficient levels, some of these contaminants are toxic to humans or fish, while others are potential carcinogens. Potential contamination from current activities. Current cleanup efforts at the Hanford site could contribute to contamination of the vadose zone and groundwater that eventually reaches the river. For example, some of the waste put into underground storage tanks as liquid has since turned into sludge or saltcake. To dissolve it, more water will have to be introduced into the tanks—including tanks known to have leaked. This process may cause additional discharges into the soil. Possible future contamination. Under DOE’s cleanup plans, and with regulator approval, a large amount of contaminants will remain on-site long into the future. This contamination may be in buildings, in mostly empty underground tanks, in covered burial grounds and waste disposal areas, and in approved disposal facilities. Contaminants may leach out of these facilities in the future and join existing contamination in the vadose zone and migrate to the groundwater, where they could migrate to the river. 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 contains 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 Office of Groundwater and Soil Remediation under the Assistant Secretary for Environmental Management sets overall policy and oversight for groundwater and soil remediation. At the Hanford site, both the Richland Operations Office and the Office of River Protection, as well as several contractors, are involved in groundwater and vadose zone activities. The monitoring of river and shoreline conditions, and groundwater sampling, is managed by the Pacific Northwest National Laboratory (PNNL). Analysis of the samples is performed by several approved laboratories. Funding for groundwater and vadose zone activities at the site is difficult to identify due to the large number of organizations and activities involved and the structure of DOE’s budget accounts. However, monitoring, characterization, well drilling and maintenance, remediation, and research activities received nearly $175 million in fiscal year 2006. DOE is taking steps to better understand the risk to the Columbia River from Hanford site contamination and to replace ineffective cleanup technologies. Specifically, DOE is addressing problems with three main aspects of its Columbia River protection efforts. First, DOE and its regulators have agreed that additional investigation of contamination in the vadose zone is needed, although doing so could delay by about 3 years the date by which DOE will propose its cleanup plans to the regulators. Second, DOE is reworking its approach to modeling the future effects of contamination on river conditions. DOE abandoned past modeling efforts in response to criticism that the models used inconsistent assumptions, were based on data of questionable reliability, and had weak quality control processes. Third, in response to concerns about the effectiveness of some of the technologies DOE had deployed to remove or contain contamination near the river, and with specific direction from Congress, DOE is evaluating alternative technologies that may be more effective at addressing the contamination. While DOE has extensive knowledge of the contaminants in the river and groundwater, and the movement of contaminants in the groundwater and on or near the surface, DOE has only recently developed limited information about the extent and location of the contamination that has migrated from the surface areas into the vadose zone above the groundwater. Understanding the nature of vadose zone contamination is critical to determining the most appropriate steps to take to protect the river now, and in future years, because contaminants still in the soil may continue to migrate until they eventually reach the groundwater and the river. DOE has studied some portions of the vadose zone, such as around the underground storage tanks, where extensive contamination from leaks and spills occurred in the past. In doing so, DOE found that some contamination, including technetium-99, had migrated as far as the groundwater. DOE contractors were able to map the migration of some of these contaminants. However, DOE acknowledges that its understanding of contaminants in the vadose zone is limited in many areas of the site. For example, cribs and trenches near the underground tanks received large volumes of contaminated wastes that dispersed directly to the ground. DOE has little information on the extent and location of the contamination in those areas, according to DOE officials responsible for planning their cleanup. They also said that characterization of the lower portions of the vadose zone is difficult and expensive, and few remediation techniques have been developed or tested for removing or isolating wastes that are located deep in the vadose zone. Understanding the extent of vadose zone contamination is critical because some contaminants still in the soil may continue to migrate until they eventually reach the groundwater and the river. Thus, understanding the type and volume of contaminants in the vadose zone and their rate of migration is essential to determining the most appropriate steps to take to protect the river now, and in future years. After finding unexpected contaminant migration in the vadose zone at one waste disposal area known as BC cribs—a location where liquids were discharged directly into the ground—DOE agreed with its regulators that its understanding of the vadose zone was inadequate to support the development of a final cleanup remedy for that area and some others. Although DOE had originally planned to defer some of its study of the vadose zone until after December 2008, when draft cleanup plans were due, DOE now agrees that more sampling and analysis of the vadose zone is needed to guide cleanup decisions. As a result, DOE has proposed to regulators to extend the date for submitting draft cleanup plans until 2011. DOE officials said this will allow the time needed to develop a better understanding of vadose zone conditions and to investigate potential remedies. In response to the discovery that its previous models to estimate the future risks of the movement of contamination toward the river were based on data of questionable reliability, DOE has begun reworking these efforts. While DOE relies on sampling to determine current conditions, it uses computer simulation models to predict future conditions and estimate future risks. In 1998, DOE groundwater program officials said DOE concluded from its simulation models that the migration was slow enough that the contaminants included in the study would not exceed their limits for 1,000 years into the future. However, DOE was concerned about the completeness of the model and began an effort, known as the System Assessment Capability, to develop a more comprehensive model. This $16 million, 8-year effort was cancelled when, in the course of a lawsuit over Hanford’s disposal plans, several quality assurance problems were found, including discrepancies in the data. DOE abandoned the past modeling efforts in response to criticisms that the models used inconsistent assumptions, were based on data of questionable reliability, and had weak quality control processes. In January 2006, DOE and Washington State settled the lawsuit. In the settlement agreement, DOE agreed to re-analyze and update its study of the cleanup’s effect on groundwater. In addition, DOE agreed to consolidate two studies of the cleanup’s effects on groundwater into a single, integrated study. Both DOE and its regulators have determined that the results of all three of DOE’s approaches to treating groundwater—pump-and-treat, chemical treatment, and natural attenuation—are not fully satisfactory. Specifically: Pump-and-treat. In a 2004 report, the DOE Inspector General concluded that the pump-and-treat system to remove strontium-90 was ineffective and that the other four pump-and-treat systems have had mixed results. However, Hanford’s acting groundwater project manager told us that four of the five pump-and-treat systems at the Hanford site meet the remedial objectives agreed to with Hanford’s regulators. The official acknowledged that the system to remove strontium-90 was largely ineffective and that DOE had been trying to obtain permission from the regulators to turn it off. Both DOE and the regulators told us that the regulators refused to allow the system to be turned off, however, until a more effective remedy was found.