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Suggested Citation:"2 Conceptual Framework." National Research Council. 2000. Long-Term Institutional Management of U.S. Department of Energy Legacy Waste Sites. Washington, DC: The National Academies Press. doi: 10.17226/9949.
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2

Conceptual Framework

Any sites retaining hazardous contaminants over a long time period will require specific forms of dedicated and ongoing vigilance. To focus and systematize its review of the major challenges that the U.S. Department of Energy (DOE) will face as sites undergo the transition from mission-oriented operations to remediation and closure as described in Chapter 1, the committee devoted the initial period of its study to developing a conceptual framework for long-term site disposition decisions. This chapter presents an overview of the committee's conceptual framework —long-term institutional management . The emphasis is on sites that face the prospect of continued management over very long periods of time.

GENERAL REQUIREMENTS

The committee's conceptual framework embodies the considerations that must be taken into account for planning remediation and stewardship activities at individual sites. In all cases reviewed by the committee, current DOE remediation planning and planning for post-remediation site stewardship can fit within the conceptual framework. In no case reviewed, however, was planning and management developed to a degree that the committee's framework suggests it should be.

Long-term institutional management of contaminated sites should be:

  • realistic in being based on recognition of practical constraints as well as capabilities;

  • systematic in its overall approach; and

  • integrative and comprehensive in its consideration of three measures:

    1. the types of contaminant reduction measures employed;

    2. the types of contaminant isolation measures employed; and

    3. the reliance placed on stewardship measures,

so that the balance achieved among reliance on each of these three types of measures is appropriate given the following contextual factors:

  • risks to members of the public, workers and the environment;

  • technical and institutional capabilities and limitations and the current state of scientific knowledge;

Suggested Citation:"2 Conceptual Framework." National Research Council. 2000. Long-Term Institutional Management of U.S. Department of Energy Legacy Waste Sites. Washington, DC: The National Academies Press. doi: 10.17226/9949.
×
  • costs and related budgetary considerations;

  • legal and regulatory requirements;

  • values and preferences of interested and affected parties; and

  • impacts on other sites.

Each of these contextual factors will receive different emphasis at different sites, depending on the site characteristics and the surrounding areas and populations, as well as social, economic, legal, and political considerations at both the local and national levels. The application of long-term institutional management should also be:

  • phased and iterative in its execution over time, with goals that are themselves adjusted over time in response to changing knowledge and public opinion, and the establishment of responsible and authoritative organizations to ensure that the goals are met;

  • adaptive in the face of future opportunities or challenges to improve upon imperfect solutions imposed by technological and other constraints; and

  • active in its search for knowledge that reduces uncertainties and in seeking the technical, institutional, and financial means to improve upon past decisions.

committee's conceptual framework for long-term institutional management is the metaphor of a three-legged stool, with its legs corresponding to the three measures mentioned above —contaminant reduction, contaminant isolation, and stewardship. This metaphor is useful for two principal reasons. First, it highlights the measures that must be present for the metaphorical stool, viewed as a “system,” to be complete and stable. Second, it emphasizes the interrelationships among these measures that are necessary to maintain that integrity over time and to give the stool the overall character that it needs, given the environment in which it will be used.

The three-legged stool that symbolizes long-term institutional management of contaminated sites is illustrated in Figure 2. The stool's legs symbolize the principal measures available to managers making disposition decisions aimed at site completion in the sense defined in Chapter 1. Contamination reduction measures (Chapter 3) are actions taken to reduce the amount of contamination by removal or in situ destruction (e.g., bioremediation). Contamination isolation measures (Chapter 4) are engineered measures implemented to stabilize, fix, or impede release of or access to contamination at a site. Physical barriers, and chemical or thermal fixation of wastes, are included in this category, as are “pump-and-treat” (or “pump-and-reinject”) actions aimed at retarding migration of subsurface plumes. Natural attenuation (including radioactive decay) is also included. Remedial action measures are, then, any combination of contaminant reduction and contaminant isolation measures. Stewardship measures (Chapter 5) include measures to maintain contaminant isolation and reduction technologies and to monitor the migration and attenuation of residual contaminants, as well as such measures as land use and access restrictions (institutional controls), oversight and enforcement, information management, and periodic reevaluation of protective systems. The latter include consideration and use of new technological options to reduce, eliminate, or contain residual contaminants.

Like any metaphor, the three-legged stool as a metaphor for long-term site management is not perfect. It will not apply, for example, in situations where contaminant reduction is sufficient to allow unrestricted use or if engineered contaminant isolation measures are not required. At complicated sites, however, some reliance on all three of the functions represented by the stool's legs—contaminant reduction, contaminant isolation, and stewardship measures—can usually be expected. Also, the three measures are not as independent of one another as the figure suggests, as stewardship, properly construed, applies to each of the other two legs.

In many cases, the three sets of measures will bear a “funnel” relationship to one another. Remediation occurs first, then containment barriers are applied to the residual that remains, and then institutional controls are developed to protect humans and the environment from harm. The three-legged stool metaphor emphasizes the dependency on all three measures at the expense of indicating the actual order of application in some instances. In doing so, however, it serves to make a key point that stewardship is a pervasive concept and not simply a set of measures to be implemented once remediation is complete.

The emphasis placed on each of these three basic measures in site disposition decisions will depend on the

Suggested Citation:"2 Conceptual Framework." National Research Council. 2000. Long-Term Institutional Management of U.S. Department of Energy Legacy Waste Sites. Washington, DC: The National Academies Press. doi: 10.17226/9949.
×

FIGURE 2 Long-term institutional management conceptual framework.

capabilities and limitations of each, as well as on the nature of the site problem that is being addressed (i.e., metaphorically, the terrain upon which the stool is to rest), and in part on broader contextual factors (such as risks, costs, public values, legal and regulatory requirements, technical and institutional capabilities and scientific knowledge, and impacts on other sites). The latter are symbolized by the rungs of the stool, which, metaphorically speaking, connect and fix the legs. The role that such factors play in long-term disposition decisions is elaborated upon in Chapter 6. The rugged terrain on which the stool rests (illustrated in Figure 2) is intended to represent the wide range of contamination characteristics present between and within sites that will drive decisions toward determining the appropriate balance of reliance to be placed on contaminant reduction, contaminant isolation, and stewardship measures, given site characteristics.

The legs of the stool in Figure 2 support a seat that symbolizes a planned end state, which may or may not be

Suggested Citation:"2 Conceptual Framework." National Research Council. 2000. Long-Term Institutional Management of U.S. Department of Energy Legacy Waste Sites. Washington, DC: The National Academies Press. doi: 10.17226/9949.
×

the final goal envisioned for the site. Here again, the limitations of the metaphor must be recognized. In some ways the seat is the ultimate purpose of the stool—it is both an end in itself and the means by which desired future site uses can be achieved—but, at the same time, the distinctly limited capabilities to anticipate changes at a site, or in society and its technologies more broadly, must be acknowledged. For example, the range of possible future land uses may broaden as remediation technologies improve. On the other hand, the range of potential land uses may narrow, or unsuspecting future citizens could be exposed to unacceptable risks, if contaminant isolation or stewardship measures begin to fail.

In the conceptual model, progress toward planned goals occurs in stages. This iterative, phased feature of long-term disposition decision making is symbolized by the successive layers of rungs (or interim states) in the stool pictured in Figure 2. Interim cleanup goals are currently in wide use throughout the DOE complex, and even where end state goals have been selected, they may have been set provisionally. Or, the remedial actions necessary to achieve them may need to unfold in successive stages over fairly long periods of time. As will be discussed in Chapter 7, there is a clear need to recognize that, at present, we do not have reasonable assurance that such followthrough can reliably be counted on to occur. Successive stages of evaluation could involve reconsideration of the goals previously selected, or adjustment of how the three sets of measures symbolized by the stool's legs are to be applied to attain the selected goals. Finally, the nature and relative importance of the individual contextual factors that make up the rungs, and the interrelationships among these factors, can also change through time.

SITE DISPOSITION DECISIONS FROM A LONG-TERM INSTITUTIONAL MANAGEMENT PERSPECTIVE

The sites and situations that the committee considered are extremely varied in character. Neither within the DOE complex nor with regard to contaminated industrial sites in the private sector do many generalizations apply to all waste site disposition decisions. This section elaborates on selected aspects of the committee's long-term institutional management framework as applied to current practice or planning at individual sites.

“End States” as Guides to Site Disposition Decisions

The iterative or phased character of remediation efforts, with goals successively defined and redefined, was apparent at many of the DOE sites visited by the committee. Although individual remediation actions are usually directed at relatively well-defined end states (typically, cleanup goals set by the U.S. Environmental Protection Agency [EPA] or state regulators for groundwater or soils), the ultimate end state for the site as a whole may for all intents and purposes be unknown, and may remain so for a considerable time as site remediation proceeds. Especially for the larger sites, end states appear at present to be emerging as the de facto result of multiple interim actions. These interim actions are aimed at achieving interim states and are being applied in serial fashion via regulatory definition to often relatively small and relatively dispersed, former operational units within the larger site, or facilities or disposal areas within operational units.

The effect of cleanup proceeding this way is to produce a relatively clean site with pockets that may remain contaminated and therefore in need of institutional management into the indefinite future. The larger sites within the DOE defense complex appear to be evolving toward a “Swiss cheese” configuration, which while potentially able to support multiple uses in land areas where successful contaminant reduction or the lack of contamination in the first place enables unrestricted use, may also present challenges for ongoing management efforts in other areas where stewardship measures are required because residual contamination persists and represents a hazard.

One example of site cleanup proceeding this way is the program of soils cleanup at the Hanford Site 100 Area, adjacent to the Columbia River. Cleanup is guided by highly specific target decontamination levels tailored to the risk to a hypothetical future resident atop the filled pits and trenches that are small parts of defined operational units. Disposition of reactors, spent fuel sites, buried wastes, and other nearby contaminated sites is proceeding on separate tracks and time scales, with relatively few final decisions yet made about the specifics and ultimate goals of remediation efforts (particularly with regard to the ultimate disposition of reactors and contaminated groundwater plumes).

Suggested Citation:"2 Conceptual Framework." National Research Council. 2000. Long-Term Institutional Management of U.S. Department of Energy Legacy Waste Sites. Washington, DC: The National Academies Press. doi: 10.17226/9949.
×

This fragmented decision-making approach appears to have developed for a variety of reasons. Under the Comprehensive Environmental Response, Compensation, and Liability Act of 1980, as amended (CERCLA) and the Resource Conservation and Recovery Act of 1976 (RCRA), the dominant federal laws governing cleanup at most DOE sites, cleanup goals are likely to be negotiated over time on an operational unit or solid waste management unit basis. (Appendix E contains a summary of the legal structure for closure of DOE sites.) When wastes are left on site, as is likely at most large sites, all operable units may not be able to achieve the same cleanup goals. For example, the presence of DNAPLs (dense, non-aqueous phase liquids), metals, or other difficult-to-address contamination problems may mean that cleanup levels (i.e., ARARs—applicable or relevant and appropriate requirements—under CERCLA) may not be achievable and a finding of technical impracticability may be made under CERCLA (National Research Council, 1999e). As demonstrated by the Hanford Site 100 Area, cleanup will tend to move forward on problems where agreement exists, while decisions in other areas of the larger cleanup problem are deferred.1

The ultimate disposition of contaminated facilities within larger areas undergoing remediation can also strongly influence the end state that is achievable for the larger area. An example includes the plutonium production reactors in the 100 Area at the Hanford Site where the C Reactor has recently been put into “interim safe storage” by placing it in a “cocoon” that has a 75-year design life (see Sidebar 2-1). But major decisions remain to be made on the disposition of the reactors in the 100 Area as a group. Current options range from permanent entombment in place (following removal of the reactor cores to permanent disposal in the 200 Area, the Hanford Site's central waste management area) to physical removal of entire reactor buildings to this same area. One variant has the historic B Reactor remaining on site to become a museum, open for public visits.

Even where future land use preferences guide the choice of remediation end points, the experience of the EPA Superfund program suggests that the correlation between land use preferences and end point selection is poor (Hersh et al., 1997). Thus, exit point from a particular phase in site management is perhaps a more accurate term than end state to define site condition at the point where remediation ends. An absence of the kind of systems-oriented thinking that is espoused in the committee's long-term institutional management framework is evident in these examples drawn from the Hanford Site. A systems engineering approach for analyzing various pathways with related uncertainties toward an end point has been discussed in several recent reports about cleanup of Hanford from the National Research Council (1998a, 1999d).

Tradeoffs Between Present-Day Remediation and the Need for Long-Term Stewardship

For numerous contamination problems within the DOE complex, site disposition decisions rely heavily on engineered containment and subsequent stewardship activities. The situations are quite varied and include cases where fairly extensive waste removal is being undertaken, as well as those in which relatively little waste is being removed. Examples in the latter category include natural attenuation sites and sites receiving “technical impracticability” waivers under EPA guidelines (National Research Council, 1999e).2 While technical impracticability waivers have to date been applied on a very contaminant- and situation-specific basis, these cases will nevertheless

1  

Although there is strong local support for the approach being taken to the Hanford Site 100 Area soils cleanup, the use to which these lands along the Columbia River are ultimately to be put remains undecided. The DOE Inspector General (IG) has argued for less stringent cleanup standards than those in use in the soils cleanup, stating that residential standards are inappropriate to the future land uses that are most likely to be adopted. The IG estimates that a cost savings of $12 million would result from the remediation of just the first few of the 70 or so soil sites if they are cleaned up to a “rural-residential ” land use scenario (Seattle Post-Intelligencer, July 8, 1999). Under current plans a total of some 3 million cubic yards of soil and solid waste will be excavated (U.S. Department of Energy, 1999, Appendix E).

2  

EPA's “technical impracticability” waiver guidance is aimed at DNAPLS and similar difficult-to-remedy groundwater cleanup problems found at Superfund sites. DOE's contention that some cleanup problems around the complex (e.g., the underground test cavities at the Nevada Test Site [see Appendix F], the hydrofracture zones at the Oak Ridge Site) are technically impractical to clean up does not constitute a regulatory determination to that effect. There is no formal process for making such declarations with respect to DOE sites, other than where the contaminants are similar to those for which such declarations have been made at privately owned sites.

Suggested Citation:"2 Conceptual Framework." National Research Council. 2000. Long-Term Institutional Management of U.S. Department of Energy Legacy Waste Sites. Washington, DC: The National Academies Press. doi: 10.17226/9949.
×

SIDEBAR 2-1

HANFORD SITE REACTOR ‘INTERIM SAFE STORAGE'

In the Hanford 100 Areas, one reactor, the C Reactor, has been put into an “interim safe storage” condition (Richland Environmental Restoration Project and Bechtel Hanford, Inc., 1999). Construction on this water-cooled, graphite-moderated production reactor was begun in June 1951 and it was started up in November 1952, just 17 months after groundbreaking. It was one of nine constructed between 1942 and 1955 at the Hanford Site along the Columbia River to produce weapons-grade plutonium. The reactor was shut down in April 1969, and deactivation was completed in early 1971.

The C Reactor building was 106 m by 93 m (346 feet by 305 feet) in size, with a height of 30 m (98 feet) and constructed of reinforced concrete in its lower levels and the central portions surrounding the reactor. The design objectives for the interim safe storage included:

  • safe storage for up to 75 years;

  • no releases of radionuclides to the environment under normal design conditions;

  • required interim inspections on a 5-year frequency basis; and

  • completion of a safe storage enclosure configuration that would not preclude or significantly increase the cost of any final decommissioning alternative.

The safe storage condition for the reactor building included several significant steps. A significant portion of the structure outside of the reactor was removed (reducing its area by about 80 percent of its original size). Before this occurred, the highly contaminated sediments from the irradiated fuel element discharge area that were stored in the fuel storage basin transfer pits were encapsulated in grout to form monoliths. Finally, the remaining reactor core was encased in 3- to 5-foot thick concrete shielding walls and a corrosion resistant galvanized steel roof. Although initial planning for the C Reactor decontamination and decommissioning project included filling the main reactor building with grout, this element of safe storage enclosure construction was abandoned out of concern that grouting might preclude later dismantling of the entire reactor structure and moving it to the waste management area on the site's central plateau (the 200 Areas). The safe storage enclosure was completed in September 1998.

Major decisions remain to be made on the disposition of the production reactors as a group, with current options ranging from permanent entombment in place to physical removal of the main reactor buildings in whole or in pieces to the Hanford Site's central waste management area (the 200 Areas). It has been suggested that reactor building removal could be accomplished via tracked vehicles similar to those used to move the Space Shuttle to its launch pad. An interesting variant on all these options has the B Reactor remaining on site to become a museum to the Atomic Age, open for public visitation. The consequences of this latter possibility for current cleanup planning for nearby lands within the 100 Areas have as yet received scant attention.

REFERENCE

Richland Environmental Restoration Project and Bechtel Hanford, Inc. 1999 (February). Submittal for 1998 Project of the Year—C Reactor Interim Safe Storage. Richland, Wash.

often necessitate that humans and the environment be protected from contact with contaminants for very long periods of time.

Where physical systems like pump-and-treat are employed, they may need to be maintained in good working order for very long time periods, placing additional burdens on site stewardship. At Hanford, some 85 square miles of the site are underlain by contaminated groundwater that currently does not meet drinking water standards (U.S.

Suggested Citation:"2 Conceptual Framework." National Research Council. 2000. Long-Term Institutional Management of U.S. Department of Energy Legacy Waste Sites. Washington, DC: The National Academies Press. doi: 10.17226/9949.
×

Department of Energy, 1999, Appendix E). Groundwater plumes are contaminated with radionuclides and other hazardous chemicals and are now impinging on the Columbia River. A pump-and-reinject system of wells is in use in the 100 Area in an attempt to retard migration of strontium into the river. The intention is that natural decay will reduce radiation levels to drinking water standards (8 pCi/l for strontium) before significant release to the river occurs. With strontium-90 having a half-life of 29 years, such an operation may have to be run for about 300 years to reduce the radioactivity by a factor of about 1,000.

Choices between reduction of contaminants now and continued reliance on contaminant isolation and stewardship measures far into the future exist throughout the complex. At the Nevada Test Site (NTS), for example, fairly extensive surface soils cleanup has been directed at plutonium dust and fragments (the result of subcritical nuclear testing), while no remediation is contemplated for the underground test cavities (Appendix F). DOE has attempted to set goals for cleanup at NTS that it believes are consistent with the site's anticipated future use as a high-security standby site for the possible resumption of underground nuclear testing and its relative remoteness from human populations. Some commercial use of the NTS is also contemplated, possibly including a satellite launching center.

Adaptability and Flexibility in Remediation Approaches

At DOE sites for which no currently known waste removal option exists, the long-term nature of the problem poses a dilemma. The inability to foresee future land use, possible failure of containment barriers or other remediation technologies or development of better ones, or the character of future society, are all factors that point to the need for building adaptability and flexibility into current site remediation planning. Adaptive and flexible approaches can take a wide variety of forms (for example, the Hanford Site reactor “interim safe storage”, see Sidebar 2-1). The Hanford decision to abandon the use of grout vaults for on-site disposal of the low-activity fraction of the wastes separated and removed from the high-level waste stored in underground tanks in the 200 Area was based in part on similar considerations. This decision shifts from disposal of these wastes in the 200 Areas in the form of grout vaults to the form of containers of vitrified waste that can be stored in a variety of locations, albeit with their own inherent problems.

In summary, long-term institutional management is a concept that represents a systematic approach to protect the public and the environment from contaminants that remain at sites upon cessation of remediation activities. It includes three sets of measures that are supported by applying the results of the new scientific understanding and technical development:

  1. contaminant reduction—actions that may be applied to reduce the level of risk presented by the residual contaminants;

  2. contaminant isolation—actions taken to monitor existing barriers to residual contaminant migration and to reduce the chance of migration in the future; and

  3. stewardship—actions taken by responsible authorities to protect the public and the environment from risks present at residually contaminated sites.

Although these three sets of measures may be implemented sequentially, planning and decision making for them must be conducted simultaneously, based on the existing conditions and the desired end point. Affecting these measures are a number of contextual factors, many of which address the uncertainty of present and future capabilities and limitations. These three sets of measures and the contextual factors will be discussed in greater detail throughout this report. The committee uses terms relevant to institutional management, as described in this chapter, throughout the report: definitions of the terms are listed in Appendix I.

Suggested Citation:"2 Conceptual Framework." National Research Council. 2000. Long-Term Institutional Management of U.S. Department of Energy Legacy Waste Sites. Washington, DC: The National Academies Press. doi: 10.17226/9949.
×
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Suggested Citation:"2 Conceptual Framework." National Research Council. 2000. Long-Term Institutional Management of U.S. Department of Energy Legacy Waste Sites. Washington, DC: The National Academies Press. doi: 10.17226/9949.
×
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Suggested Citation:"2 Conceptual Framework." National Research Council. 2000. Long-Term Institutional Management of U.S. Department of Energy Legacy Waste Sites. Washington, DC: The National Academies Press. doi: 10.17226/9949.
×
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Suggested Citation:"2 Conceptual Framework." National Research Council. 2000. Long-Term Institutional Management of U.S. Department of Energy Legacy Waste Sites. Washington, DC: The National Academies Press. doi: 10.17226/9949.
×
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Suggested Citation:"2 Conceptual Framework." National Research Council. 2000. Long-Term Institutional Management of U.S. Department of Energy Legacy Waste Sites. Washington, DC: The National Academies Press. doi: 10.17226/9949.
×
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Suggested Citation:"2 Conceptual Framework." National Research Council. 2000. Long-Term Institutional Management of U.S. Department of Energy Legacy Waste Sites. Washington, DC: The National Academies Press. doi: 10.17226/9949.
×
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Suggested Citation:"2 Conceptual Framework." National Research Council. 2000. Long-Term Institutional Management of U.S. Department of Energy Legacy Waste Sites. Washington, DC: The National Academies Press. doi: 10.17226/9949.
×
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It is now becoming clear that relatively few U.S. Department of Energy (DOE) waste sites will be cleaned up to the point where they can be released for unrestricted use. "Long-term stewardship" (activities to protect human health and the environment from hazards that may remain at its sites after cessation of remediation) will be required for over 100 of the 144 waste sites under DOE control (U.S. Department of Energy, 1999). After stabilizing wastes that remain on site and containing them as well as is feasible, DOE intends to rely on stewardship for as long as hazards persist—in many cases, indefinitely. Physical containment barriers, the management systems upon which their long-term reliability depends, and institutional controls intended to prevent exposure of people and the environment to the remaining site hazards, will have to be maintained at some DOE sites for an indefinite period of time.

The Committee on Remediation of Buried and Tank Wastes finds that much regarding DOE's intended reliance on long-term stewardship is at this point problematic. The details of long-term stewardship planning are yet to be specified, the adequacy of funding is not assured, and there is no convincing evidence that institutional controls and other stewardship measures are reliable over the long term. Scientific understanding of the factors that govern the long-term behavior of residual contaminants in the environment is not adequate. Yet, the likelihood that institutional management measures will fail at some point is relatively high, underscoring the need to assure that decisions made in the near term are based on the best available science. Improving institutional capabilities can be expected to be every bit as difficult as improving scientific and technical ones, but without improved understanding of why and how institutions succeed and fail, the follow-through necessary to assure that long-term stewardship remains effective cannot reliably be counted on to occur.

Long-Term Institutional Management of U.S. Department of Energy Legacy Waste Sites examines the capabilities and limitations of the scientific, technical, and human and institutional systems that compose the measures that DOE expects to put into place at potentially hazardous, residually contaminated sites.

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