THE NATIONAL ACADEMIES

Advisers to the Nation on Science, Engineering, and Medicine

National Academy of Sciences

National Academy of Engineering

Institute of Medicine

National Research Council

Board on Radioactive Waste Management

June 11, 2002

Jessie Roberson

Assistant Secretary

Office of Environmental Management

U.S. Department of Energy Washington, DC20585

Dear Assistant Secretary Roberson:

At the direction of Congress, you asked the National Academies to assist the Department of Energy (DOE) in developing a plan for remediation of the Moab Site. This site, located adjacent to the Colorado River in Moab, Utah, contains a pile of roughly 12 million tons of uranium mill tailings and contaminated soils. The National Research Council, the chief operating arm of the National Academies, charged its Committee on Long-Term Institutional Management of DOE Legacy Waste Sites: Phase 2 with providing the requested assistance (see Appendix B of the accompanying report for the committee roster). Specifically, based on the congressional directive, the committee was asked to provide technical advice and recommendations to assist DOE in objectively evaluating costs, benefits, and risks associated with remediation alternatives for the Moab Site, including removal or treatment of radioactive or other hazardous materials at the site, ground-water restoration, and long-term management of residual contaminants. This letter summarizes the committee’s major findings and recommendations. The accompanying body of the report elaborates on these, focusing primarily on a critical examination of the technical basis available to DOE for selecting a remediation plan for the site. As explained below, and in the body of the committee’s report, the committee concludes that the current technical basis is not adequate to support a decision at this time.

DOE faces a decision between two main alternatives for remediation of the Moab Site: stabilize the pile in place or relocate the pile. All of the specific remediation options are variations on these two alternatives. Other aspects of the site remediation can be understood in relation to the decision between the main alternatives. The committee concludes that a closure path for the Moab Site is not ripe for decision because:

  • the pile, the Moab Site, and possible sites for a relocated disposal cell have not been characterized adequately;

  • the options for implementing the two primary remediation alternatives have not all been identified or sufficiently well defined;

  • the risks, costs, and benefits of the major alternatives have not been adequately characterized and estimated; and

  • the long-term-management implications for each option have not been described.

The committee further concludes that the additional data and analyses needed to enable a decision can be developed with a limited, focused effort.



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THE NATIONAL ACADEMIES Advisers to the Nation on Science, Engineering, and Medicine National Academy of Sciences National Academy of Engineering Institute of Medicine National Research Council Board on Radioactive Waste Management June 11, 2002 Jessie Roberson Assistant Secretary Office of Environmental Management U.S. Department of Energy Washington, DC20585 Dear Assistant Secretary Roberson: At the direction of Congress, you asked the National Academies to assist the Department of Energy (DOE) in developing a plan for remediation of the Moab Site. This site, located adjacent to the Colorado River in Moab, Utah, contains a pile of roughly 12 million tons of uranium mill tailings and contaminated soils. The National Research Council, the chief operating arm of the National Academies, charged its Committee on Long-Term Institutional Management of DOE Legacy Waste Sites: Phase 2 with providing the requested assistance (see Appendix B of the accompanying report for the committee roster). Specifically, based on the congressional directive, the committee was asked to provide technical advice and recommendations to assist DOE in objectively evaluating costs, benefits, and risks associated with remediation alternatives for the Moab Site, including removal or treatment of radioactive or other hazardous materials at the site, ground-water restoration, and long-term management of residual contaminants. This letter summarizes the committee’s major findings and recommendations. The accompanying body of the report elaborates on these, focusing primarily on a critical examination of the technical basis available to DOE for selecting a remediation plan for the site. As explained below, and in the body of the committee’s report, the committee concludes that the current technical basis is not adequate to support a decision at this time. DOE faces a decision between two main alternatives for remediation of the Moab Site: stabilize the pile in place or relocate the pile. All of the specific remediation options are variations on these two alternatives. Other aspects of the site remediation can be understood in relation to the decision between the main alternatives. The committee concludes that a closure path for the Moab Site is not ripe for decision because: the pile, the Moab Site, and possible sites for a relocated disposal cell have not been characterized adequately; the options for implementing the two primary remediation alternatives have not all been identified or sufficiently well defined; the risks, costs, and benefits of the major alternatives have not been adequately characterized and estimated; and the long-term-management implications for each option have not been described. The committee further concludes that the additional data and analyses needed to enable a decision can be developed with a limited, focused effort.

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Based on these conclusions, the committee makes the following recommendations: (I) DOE should undertake further, but bounded, investigations of several unresolved questions related to science and engineering in order to arrive at a sound remediation decision. (II) DOE’s decisionmaking process should recognize the connections and potential tradeoffs between short- and long-term actions. (III) DOE should critically examine important assumptions and conclusions in its analyses of the two primary alternatives, examine the likelihood that they might be invalid over the relevant time frames, and reassess the risks in this new light. (IV) DOE should continue to plan remediation of the site in a way that explicitly involves the public, consistent with good risk-based decision-making practice. (V) DOE should draw more explicitly from its own experience in managing tailings piles in developing its plan for remediation at Moab. (VI) Issues that will not result in a net difference between the remediation alternatives (e.g., issues that require the same action under either remediation alternative) should not confuse the remediation decision-making process. These recommendations are further explained below, and documented in detail in the body of the committee’s report. Much of the body of the committee's report raises questions regarding the stabilize-in-place alternative. This is an incomplete focus, however, and could produce a misunderstanding of what DOE needs for its decision on a remediation alternative. The committee, like DOE, has worked from the information available, closely examining aspects of stabilizing the pile in place because that alternative was developed more extensively. Less attention has been devoted to the relocate alternative because DOE has only a superficial knowledge of most of the sites under consideration for the relocate alternative and of the impacts of transporting the tailings. Therefore, fuller development of alternatives is needed. Until the relocate alternative is better characterized and the committee’s findings and recommendations are addressed, it is premature to decide that one site is better than another or that one remediation alternative is better than another. In part for these reasons, the committee’s report does not identify a preferred remediation alternative. In addition, that decision involves tradeoffs among human-health risk (public and worker), environmental hazards, costs (including opportunity costs), and other relevant considerations. While the committee makes recommendations about what factors should be considered in making these choices, the decisions themselves are properly made by elected and appointed government officials. DOE should undertake further, but bounded, investigations of several unresolved questions related to science and engineering in order to arrive at a sound remediation decision. Over the years, the former site owner, a bankruptcy trustee, and the U.S. Nuclear Regulatory Commission (U.S. NRC) have worked with several contractors to analyze different aspects of the pile and the site. The information in these studies is insufficient to provide an understanding of the health and environmental risks and other matters that are needed to inform the decision. The documents and reports preceding DOE’s involvement were prepared to support a license amendment to close the site by capping the pile in place. U.S. NRC had to decide whether to approve that particular application; it was not charged with identifying and selecting the best approach for remediation, accounting for all of the relevant factors. DOE is not responsible for the previous studies, and only limited new studies could be completed for the committee’s review, because DOE only received funding for work at the site in July 2001. DOE does, however, have responsibility for ensuring that the information upon which it bases the remediation decision is sufficient and of high quality. The committee recommends that DOE undertake a bounded process of fact-finding and analysis before reaching a final decision on site remediation. The committee finds that previous studies either do not address or do not adequately answer a set of questions that the committee sees as critical to assessing each alternative. These questions are discussed in detail in Sections III and V of the body of the committee’s report. DOE should set priorities among these questions, addressing first those that

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most affect the remediation decision process and that are most likely to yield relevant results. These additional analyses should not be viewed as yet another postponement of site cleanup, but rather as the necessary background for a well-founded and expeditious decision. DOE’s decision-making process should recognize the connections and potential tradeoffs between short- and long-term actions. The committee suggests that the ultimate objective at the Moab Site should be to implement remediation and management measures that have the best reasonably achievable probability of being protective of human health and the environment for the duration of the hazard, taking into account relevant economic and societal factors. Federal regulations (40 CFR 192) adopt 1000 years as the design objective for the maintenance of human isolation of mill tailings from the environment. The regulations require that this objective be met “to the extent reasonably achievable,” and set a lower bound for control of “at least” 200 years. These are ambitious goals, even though they fall far short of the full duration of the hazard. Lower levels of remediation in the near term typically leave greater residual long-term hazards, which may increase the need for, the importance of, and the costs of long-term actions. The committee recommends that DOE assess each alternative for disposition of the Moab pile on the basis of its entire life-cycle, including the demands for long-term institutional management (LTIM) actions, where LTIM comprises the total system of protection, including contaminant reduction, contaminant isolation, and long-term stewardship. Thus, such an assessment would specifically include consideration of the residual risk when the near-term remediation actions at the site are complete, the LTIM measures required, the likely duration of these measures, the consequences of the failures of such measures, and the total social costs expended. DOE should consider all of these factors in establishing the balance between near-term cleanup and long-term measures, as well as in designing the LTIM measures, themselves. Long-term considerations do not necessarily outweigh short-term concerns (e.g., cost and remediation risk), but they should be identified, evaluated, and any tradeoffs explicitly identified and considered as part of the decision. DOE should critically examine important assumptions and conclusions in its analyses of the two primary alternatives, examine the likelihood that they might be invalid over the relevant time frames, and reassess the risks in this new light. The future risks from the stabilize-in-place alternative will depend on the long-term stability of the pile, the durability of the cover system, the longevity of society’s memory regarding hazards at the site, the distribution and extent of contamination in the subsurface, the ability of engineered barriers to protect against movement of the course of the Colorado River toward the pile, and the persistence of organizational capabilities to respond to failures in the pile’s integrity. In the current analysis, these issues are addressed by generally assuming that all engineered and natural systems will work as expected and that institutional memory will endure. The potential for these assumptions to be wrong, and the consequences if they are, need to be considered in more detail. These matters are discussed in Section V of the body of the committee’s report. An example of an important assumption that should be reviewed at the Moab Site is DOE’s acceptance of the U.S. NRC’s finding that the risks that the Colorado River will intercept and carry away a portion of the mill-tailings pile are small and that this eventuality can be addressed by engineered measures. In contrast, it is the committee’s view that it cannot be assumed that the course of the Colorado River will remain in its current position over the next 1000 (or more) years. While one cannot predict the timing of river migration (over the coming millennia or in the next several decades), the committee sees it as a near certainty that the river’s course will run across the Moab Site at some time in the future, unless engineered barriers prevent it from

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doing so. In addition to appropriate consideration of the probability that the river will change course, the consequences if such an event were to occur have been examined only superficially. Accordingly, DOE should assess the risks—both probabilities and consequences—associated with river-pile interactions over time. If the stabilize-in-place option is selected, explicit consideration of this failure scenario is necessary, and the risks may warrant a plan for dealing with such failures. DOE should continue to plan remediation of the site in a way that explicitly involves the public, consistent with good risk-based decision-making practice. The National Research Council has advised in previous studies that decisions that involve risk management should involve the stakeholders from the earliest phases of defining the problem through the final decision. “Adequate risk analysis and characterization … depend on incorporating the perspectives and knowledge of the interested and affected parties from the earliest phases of the effort to understand the risks. The process must have an appropriately diverse participation or representation of the spectrum of interested and affected parties, of decision makers, and of specialists in risk analysis, at each step.” (p. 3, [NRC 1996]) Public participation (including both the local public and the broader, national public) can bring important issues, concerns, perspectives, and information to the attention of decision makers in a timely manner, resulting in better decisions. In addition, extensive collaboration with the public increases understanding of the decision bases and helps create support for the decisions ultimately reached. Involving the public has particular value at Moab because of the duration of the cleanup. DOE anticipates that contaminated ground water will require treatment for decades to meet the baseline regulatory standards, regardless of the remedy selected for the pile. Involving the local community during that period reduces the likelihood that the site’s dangers will be forgotten in the longer term, and that the site would be used in inappropriate and dangerous ways. Public involvement and community support or acceptance can also form a foundation for the creation of effective institutions and practices for long-term management of residual hazards at the site. The committee finds that Moab is a promising location to pursue the recommendations of previous committees of the National Research Council addressing public participation in risk-based decisionmaking. It is particularly noteworthy that the Moab community seems ready to accept a final resolution that would keep the tailings in their own county, albeit at a location farther from the river and the town. This demonstrates a degree of receptiveness to DOE’s role and an apparent atmosphere of civic responsibility in which DOE has an opportunity to work productively with local stakeholders. The openness of DOE staff, working with local and state government and the community, has brought a positive attitude to a long-festering problem. This is a strong beginning. DOE should draw more explicitly from its own experience in managing tailings piles in developing its plan for remediation at Moab. The Moab Site is the newest, the largest, and potentially the most expensive member of the population of UMTRCA Title I sites. Every one of these sites except the Moab Site has already been put through the process of selecting and implementing a remediation plan. Thus, a comparative analysis of options, risks, and decisions at Moab in light of existing information on other UMTRCA sites could provide some important perspectives. Questions that DOE might ask regarding other sites, that could aid decision making at the Moab Site, include: Have the models used to project the behavior of the disposal cells at other sites proved to be accurate to date? Have the groundwater cleanups encountered significant surprises? Do the local communities continue to be supportive of DOE's long-term surveillance and maintenance activities? How

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can the high costs for some of the projects, measured in terms of risk reduction per dollar spent, be lowered at Moab? Have measures for LTIM been effective at these sites so far? Are there other non-UMTRCA sites with similar characteristics that have been remediated using the alternatives proposed at Moab (i.e., moved or stabilized in place) and, if so, what lessons can be learned from these sites? Are there sites where the initial decision had to be reevaluated or reversed and, if so, why? Although DOE has shared gross cost estimates and first-order cost breakdowns with the committee, the committee believes that a more thorough examination of past experiences will provide DOE with both technical and social lessons helpful in planning remediation and long-term management at Moab. The committee particularly recommends that DOE examine cost data (initial bids and final costs) to identify where the costs significantly exceeded early estimates, which could help DOE judge whether cost estimates for the remediation alternatives at the Moab Site are reliable and could be improved. Issues that will not result in a net difference between the remediation alternatives (e.g., issues that require the same action under either remediation alternative) should not confuse the remediation decision-making process. Some issues do not produce a preference for either remediation alternative, and should not confuse the remediation decision-making process. An example is the threat to potential habitats for endangered species such as the Colorado pikeminnow. Such threats can probably be mitigated temporarily by simple remedies that will be required under either alternative. For the long term, it appears that ground-water remediation will be required for reasons independent of the endangered-species issue. If both the temporary measures and the ground-water remediation are required and can be fulfilled under any remediation alternative, then there is no net difference related to endangered species. In conclusion, DOE has made a useful start to its evaluation of the Moab Site and the options for remediating it, and the committee appreciates the active cooperation of DOE staff in the committee’s study. The body of the committee’s report provides more detailed findings and recommendations that the committee hopes will help those specifically charged with planning and carrying out the site remediation. Thank you for the opportunity to assist in addressing this important issue. Sincerely, Kai N. Lee Chairman, Committee on Long-Term Institutional Management of DOE Legacy Waste Sites: Phase 2

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Table of Contents I   Introduction   7 II   Scope of the study and overall recommendations   8 III   Characterizing the primary remediation alternatives   10 IV   Addressing concerns raised under the Endangered Species Act (ESA)   11 V   Understanding interactions between water and the pile, and designing a cleanup plan for contaminated ground water.   12     A Would engineered barriers on the exterior of the pile prevent significant infiltration of water, either from precipitation or from flooding by the Colorado River, and thus prevent further contamination of ground water?   14     B Do floods and lateral migration of the river threaten long-term stability of the pile if it is stabilized in place?   17     C Can social capacity for long-term monitoring of the site(s) and appropriate response to the failure of engineered barriers be provided reliably, so that the consequences of failures can be managed?   19     D Would loss of even a substantial portion of the pile into the Colorado River produce only small and transitory consequences downstream?   22     E Is the life-cycle cost of moving the pile substantially higher than that of capping it in place, and is there almost no differential cost of ground-water remediation and long-term management between the alternatives?   23 VI   Observations about the Moab Site and its remediation   25     A Passive measures for ground-water remediation   25     B Settlement analysis of the pile during dewatering   25     C Ecological Issues   26     References   27 Appendix A   Background on the Moab area and the site   30 Appendix B   Committee Roster; Committee Member Biographies; List of Reviewers; Agenda of the January 14-15, 2002, Meeting in Moab, Utah; List of people and agencies who provided Input   39