6
Conclusions and Recommendations

The challenges to be overcome in the management of contaminated sediments are multifaceted, and there are no easy solutions. The problem is not intractable, however, as long as two key issues are addressed: forging partnerships to replace adversarial relationships; and changing laws, regulations, and practices.

To provide a framework for the committee's specific proposals, a number of general observations can be made based on the analysis presented in this report. Most important, there is no simple solution, although many people may assume there is, and there is no breakthrough technology on the immediate horizon for treating large volumes of contaminated sediments effectively and economically. Although in situ and handling technologies have been used with some degree of effectiveness, ex situ decontamination technologies are generally not affordable except when sediment volumes are small or when the benefits to public health or the environment are expected to be extremely high. Thus, near-term improvements in sediment management are likely to come from changes in the decision-making processes that will speed the implementation of solutions, improve the political acceptability of the management strategy and decisions, and apply systems engineering to reduce overall costs. In other words, there is no reason to delay urgent projects in anticipation of new technological solutions; decision makers should continue to try to make incremental improvements in the overall management process.

Some impediments to effective remedial action are legal and regulatory in nature. In some cases, the problems stem from how laws and regulations are interpreted rather than their original intent; but even these difficulties can impede the decision-making process. Some barriers could be removed through revisions



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--> 6 Conclusions and Recommendations The challenges to be overcome in the management of contaminated sediments are multifaceted, and there are no easy solutions. The problem is not intractable, however, as long as two key issues are addressed: forging partnerships to replace adversarial relationships; and changing laws, regulations, and practices. To provide a framework for the committee's specific proposals, a number of general observations can be made based on the analysis presented in this report. Most important, there is no simple solution, although many people may assume there is, and there is no breakthrough technology on the immediate horizon for treating large volumes of contaminated sediments effectively and economically. Although in situ and handling technologies have been used with some degree of effectiveness, ex situ decontamination technologies are generally not affordable except when sediment volumes are small or when the benefits to public health or the environment are expected to be extremely high. Thus, near-term improvements in sediment management are likely to come from changes in the decision-making processes that will speed the implementation of solutions, improve the political acceptability of the management strategy and decisions, and apply systems engineering to reduce overall costs. In other words, there is no reason to delay urgent projects in anticipation of new technological solutions; decision makers should continue to try to make incremental improvements in the overall management process. Some impediments to effective remedial action are legal and regulatory in nature. In some cases, the problems stem from how laws and regulations are interpreted rather than their original intent; but even these difficulties can impede the decision-making process. Some barriers could be removed through revisions

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--> to, or objectives-based application of, existing laws and regulations. Substantial uncertainties will remain, however, in methods for assessing the effects of contaminated sediments on human health and the environment and for evaluating the risks, costs, and benefits of various management options. In addition, intangible factors, such as social perceptions, will continue to have an important influence on the feasibility of particular options. The balanced consideration of risks, costs, and benefits can focus management decisions on a range of options, but qualitative judgment will continue to be the deciding factor. The following formal conclusions and recommendations are organized into three broad areas where improvement is both necessary and possible: decision making, remediation technologies, and project implementation. IMPROVING DECISION MAKING Cost-effective management of contaminated sediments requires informed decisions about the levels of analysis and action required to characterize contaminated sites, to identify and manage appropriately the risks associated with sediment contaminants, and to confirm the results of remediation or containment through monitoring. Decision making is influenced by the statutory framework for remediating contaminated sediments, the interests of stakeholders, systems engineering considerations, and approaches to decision making Improvements in each of these areas can contribute to better decision making Regulatory Constraints Because the laws and regulations that affect the characterization, management, and monitoring of contaminated sediments were originally written to address other issues (such as water quality), contaminated sediments are often treated as an afterthought. As a result, barriers to sediment management may be imposed without technical justification. Moreover, regulations tend to emphasize the mechanics of tasks (e.g., placement location) rather than an appropriate balance of risks, costs, and benefits. These features of the regulatory framework can interfere with efforts to implement the best management practices and timely, cost-effective solutions. For example, the three sets of regulations governing the evaluation of remedial alternatives use different approaches, and none fully considers either the degree of risk posed by contaminated marine sediments or the costs and benefits (i.e., economic and technical viability) of the various solutions. The MPRSA requires biological testing of dredged material to determine its inherent toxicity but does not fully consider site-specific considerations that may influence the exposure of organisms in the receiving environment, meaning that, at best, risk is considered only indirectly, and actual impacts are only approximated. This rigid approach may obstruct efforts to reach the best decision for a particular case and

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--> lead to the needless waste of scarce resources. The CWA procedures, which consider chemical and physical as well as biological characteristics in assessing whether the discharge of dredged material will cause unacceptable adverse impacts, are not risk-based, but at least they do not specify rigid pass-fail criteria; they are geared to the identification of the least environmentally damaging, practical (i.e., economically and technically viable) alternative. The Superfund remedial action program addresses risks and costs to some degree. An exposure assessment (but not a full risk analysis) is required to assess in-place risks, remedial alternatives are identified based on their capability to reduce exposure risks to an acceptable level, and the final selection involves choosing the most cost-effective solution. However, Superfund has no risk-based cleanup standards for underwater sediments. Although inconsistencies among the three sets of regulations is not a major problem in and of itself, the lack of emphasis on risks, costs, and benefits impedes efforts to reach technically sound decisions about cost-effective management. One way to change the emphasis might be through legislation. For example, the U.S. Congress, by enacting and revising environmental laws as they apply to contaminated sediments, and the EPA and USACE, in implementing these laws, could adopt objectives-based approaches that reflect an appropriate balance among risks, costs, and benefits. Conclusion The evaluation of disposal and management options needs to be based on the fullest practical consideration of the relevant risk factors as well as on technological feasibility and economic viability. Similar inattention to risk is evident in the permitting processes for sediment disposal. Currently, different types of permits must be secured for the placement of sediments in navigation channels or ocean waters as part of the construction of land or containment facilities (under the RHA), the dumping of sediment in the ocean (under the MPRSA), sediment disposal in inland waters or wetlands (under CWA), and the containment of contaminated sediments on land (under the RCRA). The regulations also distinguish between sediments removed during navigation dredging (CWA or MPRSA) and sediments excavated for environmental remediation (Superfund). In other words, the regulatory framework does not differentiate between the placement of contaminated sediments in an ecologically sensitive and commercially valuable shellfish bed and the deposition of contaminated sediments within the confining walls of an offshore containment dike or in the depths of an anoxic, deep ocean pit. The committee can see little technical justification for the inconsistent regulation of contaminated sediments, given that neither the location of an aquatic disposal site (freshwater versus saltwater) nor the reason for the dredging (navigation versus environmental remediation) necessarily affects the risks posed by the in-place contamination. In the committee's view, the regulatory regime pays

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--> little or no attention to the question of risk, focusing instead on the types of activities to be carried out—removal, placement, or treatment. The problem has been eased in some cases by objectives-based interpretation of regulations, as demonstrated by the carefully considered solution in the Port of Tacoma case history. Conclusion The failure to regulate contaminated sediments based on systematic consideration of risk management is inefficient and leads to less than optimum expenditures of time and money. Systematic, integrated decision making may also be undermined by regulations governing cost allocation and cost-benefit analysis. The federal government pays for a share of new-work dredging and all maintenance dredging through a user-fee mechanism but pays for none of the costs of sediment disposal. The local sponsors of federal navigation projects must bear the burden of identifying, constructing, operating, and maintaining the placement sites for dredged material, under the project cooperation requirement of the WRDA of 1986. This inconsistent approach to cost sharing may foster irrational allocations of scarce resources. Because the project sponsor must pay for disposal on land, whereas open-water disposal is paid for by the federal government as a component of dredging costs, the WRDA provision creates a strong preference for the latter, regardless of whether it is in society's (or the environment's) best interest. Furthermore, a local sponsor bearing the full burden of disposal costs has little incentive to seek out opportunities for the beneficial uses of dredged materials, which usually add to the project cost and may benefit third parties, such as the public. Additional inconsistencies are introduced in the area of cost-benefit analysis. Currently, an elaborate weighing of costs and benefits must be performed for new-work dredging. But no similar cost-benefit analysis is required for either maintenance dredging or the placement of dredged material. Conclusion The cost effectiveness of managing dredged material would be improved if the various elements of federal projects—including dredging and placement—were subject to consistent approaches to cost-sharing and to cost-benefit analysis. One option Congress might consider is amending the project cooperation requirement of WRDA as it relates to financial responsibility for the construction of land-based or aquatic sediment containment facilities, so that consistent cost-sharing formulas apply to dredging and placement for federal projects To ensure that costs are controlled, dredging and disposal for a project could both be subjected to cost-benefit analysis (preferably on a combined basis) and to the application of a systems engineering approach.

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--> Outreach to Stakeholders and Consensus Building To be successful, a remediation project needs strong proponents, whether federal agencies or ports The identification and timely implementation of effective solutions also depend heavily on how project proponents interact with stakeholders. Many parties—including government agencies at all levels, environmental groups, and members of the local community—have interests or stakes in the management of contaminated sediments, but they may have different perspectives on the problem and proposed solutions. Because any participant in the decision-making process can block or delay remedial action, project proponents need to identify all stakeholders and build consensus among them. The development of consensus can be fostered by using various tools, including mediation, negotiated rule making, collaborative problem solving, and effective communication of risks. Conclusion It is impossible to legislate agreement on issues that are inherently subject to debate. Therefore, the early involvement of stakeholders is important for heading off disagreements and for building consensus. Project proponents need to identify all stakeholders early in the decision-making process and continue to devote significant efforts to building relationships with stakeholders and reaching consensus. Systems Engineering The complexity of decision making can be accommodated by a systems approach in which interrelated issues and tasks are considered in concert. Systems engineering and analysis are widely used but have seldom been applied rigorously to decisions about the management of contaminated sediments. The overall goal is to manage the system in such a way that the results are optimized. In particular, a systems approach is advisable for the selection and optimization of interim and long-term control technologies. Limited resources and the high cost of technology demand that trade-offs be made and that remediation solutions be optimized. Conclusion Systems engineering techniques can enhance the cost-effectiveness of the management of contaminated sediments. The use of systems engineering in choosing a remediation technology will help ensure that the solution meets all removal, containment, transport, and placement requirements while satisfying environmental, social, and legal requirements. Approaches to Decision Making Three approaches can be applied to inform and improve decision making about contaminated sediments, particularly with respect to weighing the risks,

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--> costs, and benefits of proposed solutions: risk analysis, cost-benefit analysis, and decision analysis. The application of these approaches requires time and training Risk Analysis To ensure the cost-effective management of risks to human health and the environment, risk analysis (the combination of risk assessment and risk management) needs to be used throughout the management process. Currently, risk analysis is not fully applied in the context of managing contaminated sediments. Typically, risks are assessed only at the beginning of the decision-making process, with the focus on in-place contamination. Risks are seldom reassessed after the implementation of solutions. As a result, capabilities for evaluating management strategies and remediation technologies are limited. Extended application of risk analysis, particularly in the selection and evaluation of management strategies, would not only inform decision making in specific situations but would also provide data that could be used to evaluate generic approaches and plan future projects. The results of risk analysis are also essential ingredients for other important decision-making tools, such as cost-benefit analysis and decision analysis. Conclusion. The committee recognizes that there are uncertainties but believes that risk analysis techniques can be applied more widely than they are now in the sediment management process to improve decision making, particularly with respect to the selection and evaluation of management strategies and remediation technologies. The scientific underpinning of risk analysis as applied to contaminated sediments also requires attention. A fundamental uncertainty in current approaches lies in the methods used to assess initial risks. The effects-based testing methods currently used are being improved to include protocols for both acute and chronic effects as a basis for making decisions concerning the placement of dredged materials. The USAGE and EPA are also moving toward applying formal risk assessment to the results of bioaccumulation tests. Risk assessment will provide improved end-points, but there will still be a need to understand and interpret biological end-points in a regulatory context to determine unacceptable adverse effects. Conclusion. Continued development and risk-based interpretation of the results of effects-based testing methods would promote cost-effective management, support the quantitative evaluation of the performance of remediation technologies, and assist in the assessment and selection of options for sediment disposal and options for the beneficial use of treated sediments.

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--> Cost-Benefit Analysis Cost-benefit analysis is not applied widely to the management of contaminated sediments. It is currently used only for major new navigation dredging projects and is usually narrow in scope. However, cost-benefit analysis could be used in many cases to help identify the best strategy for managing contaminated sediments. From an economic standpoint, the best strategy is one in which benefits outweigh the costs by as the much as possible. The costs involved in the management of contaminated sediments are difficult to calculate and cannot be measured precisely, but a comprehensive cost-benefit analysis may be worth the effort in very expensive or extensive projects. Informal estimates or cost-effectiveness analysis may suffice for smaller projects. Current federal guidelines for the computation and use of benefit and cost data (generally confined to the navigation dredging context) are neither comprehensive nor applied systematically to the management of contaminated sediments. For example, the guidelines do not take into account the economic effects of shifts in transportation patterns or changes in the prices of navigation services. Conclusion. More extensive use of appropriate methods for cost-benefit analysis have the potential to improve decision making. Decision Analysis Methods are needed for balancing consideration of the risks, costs, and benefits of various sediment management strategies. One tool that can help resolve problems with multiple variables is decision analysis, which uses both factual and subjective information to evaluate the relative merits of alternative courses of action. This technique could be particularly valuable in certain situations because it can accommodate more variables (including uncertainty) and different perspectives than techniques like cost-benefit analysis that measure single outcomes. Decision analysis can also be a consensus-building tool because it enables stakeholders to explore subjective elements of contaminated sediments problems and perhaps find common ground. However, because it is technical in design and involves complex, logical computations, decision analysis is probably worth the effort only in highly contentious situations in which stakeholders are willing to devote enough time to gain confidence in the approach. Conclusion. Decision analysis could be used to help balance consideration of the risks, costs, and benefits of various management strategies in situations in which the issues are exceptionally complex and divisive.

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--> Recommendations for Improving Decision Making In addition to the suggestions for statutory changes that have already been made, the committee makes the following recommendations. Recommendation. The Environmental Protection Agency and the U.S. Army Corps of Engineers should continue to develop uniform or parallel procedures to address the environmental and human health risks associated with the freshwater, marine, and land-based disposal, containment, or beneficial reuse of contaminated sediments. Recommendation. Because consensus building is essential for project success, federal, state, and local agencies should work together with appropriate private-sector stakeholders to interpret statutes, policies, and regulations in a constructive manner so that negotiations can move forward and sound solutions are not blocked or obstructed. Recommendation. To facilitate the application of decision-making tools, the Environmental Protection Agency and U.S. Army Corps of Engineers should (1) develop and disseminate information to stakeholders concerning the available tools; (2) use appropriate risk analysis techniques throughout the management process, including the selection and evaluation of remediation strategies; and (3) demonstrate the appropriate use of decision analysis in an actual contaminated sediments case. Recommendation. The USACE should modify the cost-benefit analysis guidelines and practices it uses to ensure the comprehensive, uniform treatment of issues involved in the management of contaminated sediments. IMPROVING REMEDIATION TECHNOLOGIES Technologies for remediating contaminated sediments are at various stages of development. Sediment handling technologies are the most advanced, although there are benefits to be realized by improvements in the precision of dredging (and, concurrently, in site characterization). The state of practice for in situ controls ranges from immature (e.g., bioremediation) to rapidly evolving (e.g., capping). A number of ex situ treatment technologies exist that probably can be applied successfully to contaminated sediments, but additional R&D and full-scale demonstrations are needed to determine their effectiveness. Moreover, these technologies are expensive, and it is not certain whether unit costs would drop significantly in full-scale implementation. Ex situ containment, however, is commonplace.

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--> Overall, the uneven state of the art suggests that technologies need to be selected, combined, and optimized using a systems engineering approach. Although 100 percent effectiveness is not possible, available technologies do offer adequate solutions. A key factor in determining the utility of a remediation technology is cost. Therefore, cost issues are addressed before specific technologies. Engineering Costs of Cleanup The engineering costs of cleanup depend not only on the type of approach used but also on the number of steps involved-the more handling, the higher the cost. The costs of removing and transporting contaminated sediments (generally less than $15 to $20/yd3) tend to be higher than the costs of conventional navigation dredging for ''clean" sediments (seldom more than $5/yd3) but much lower than the costs of treatment (often more than $100/yd3). Reducing volume (i.e., removing only sediments that require treatment and entraining as little water as possible) offers greater cost savings than increasing production rates. Improved site characterization coupled with precision dredging techniques is particularly promising for reducing volume. Treatment costs may be reduced through pretreatment. For example, silt- and clay-sized particles may be separated from cleaner sand using hydrocyclones However, the cost savings vary depending on the proportion of fine-grained sediments requiring further treatment, as well as the cost of that treatment. Pretreatment is usually worthwhile only when the sediment contains a substantial fraction of relatively clean sand. Although post-cleanup data on actual costs are limited because of the small number of completed projects, numerous cost projections are available for approved or proposed projects. These figures, in the judgment of the committee, are sufficient for an evaluation of the practicality of various technologies. Conclusion Many contaminated sediments can be managed effectively using natural recovery, capping, or containment Where remediation is necessary, high-volume, low-cost technologies are the first choice, if they are feasible. Because treatment is expensive, reducing volume is very important. At the current state of practice, treatment is usually justified only for relatively small volumes of highly contaminated sediments, unless there are compelling public health or natural resource considerations Advanced treatment processes are too costly in the majority of cases of (typically low-level) contamination. The unit cost of advanced treatments will probably decline slightly as these technologies move through the demonstration phase, but it is unlikely to become competitive with the cost of less-expensive technologies, such as containment. Problems with available cost data include the lack of standardized documentation and the lack of a common basis for defining all relevant benefits and costs.

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--> The data are inconsistent with respect to the types of costs included and the units of measure (e.g., cubic yards, tons, hectares), and geographical variations in cost are not taken into account. The problem stems in part from the lack of a formal structure for reporting cost data. Even if good cost data were available, measures of effectiveness must be improved before reliable comparative analyses of technologies can be made. Conclusion Improved cost information is needed for full-scale remediation systems for fair, overall comparisons and to provide benchmarks for R&D and systems design. Although the lack of reliable cost data does not preclude project planning, better cost information would contribute to sound decision making. Remediation Technology Options In Situ Controls In situ management offers the potential advantage of avoiding the costs and material losses associated with the excavation and relocation of sediments. Among the inherent disadvantages of in situ management is that it is seldom feasible in navigation channels that are subject to routine maintenance dredging. Another limitation is that monitoring needs to be an integral part of any in situ approach to ensure effectiveness over the long term. Natural recovery is a viable alternative under some circumstances. It offers the advantages of low cost and, in certain situations, the lowest risk of human and ecosystem exposure to sediment contamination. Natural recovery is most likely to be effective where surficial concentrations of contaminants are low, where surface contamination is being covered over rapidly by cleaner sediments, or where other processes destroy or modify the contaminants thus decreasing contaminant releases to the environment over time. For natural recovery to be relied upon with confidence, the physical, chemical, and hydrological processes at a site need to be characterized adequately (although chemical movements cannot be quantified completely). Extensive site-specific studies may be required for this. Conclusion. For many projects, natural recovery is a viable option. It may be the optimum solution where surficial concentrations of contaminants are low, where surface contamination is being covered over rapidly by cleaner sediments, or where contaminated sediment is modified by natural chemical or biological processes and the release of contaminants to the environment decreases over time. A better understanding of natural processes is needed, and models need to be verified through long-term monitoring. The advantages of in situ capping are that it isolates the contaminants and may protect against sediment resuspension. At appropriate locations, capping

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--> materials can be emplaced readily and, if necessary, repaired. In situ capping requires that the original bed be able to support the cap, that suitable capping materials to create the cap are available, and that hydraulic conditions (including water depth) permit cap emplacement and will not compromise the integrity of the cap. Changes in the local substrate, benthic community structure, or bathymetry at a depositional site may subject the cap to erosion. These changes, among others, need to be verified by short-term pre-project and long-term post-project monitoring. A regulatory barrier to the use of capping is the language of Superfund legislation (§121[b]), which gives preference to "permanent" controls. Capping is not considered by regulators to be a permanent control, but the available evidence suggests that properly managed caps can be effective in reducing risks associated with underwater sediments. Furthermore, capping may be preferable to some other strategies because it is relatively inexpensive and easy to implement, and it capitalizes on the tendency of contaminants to remain bound to sediment particles and to settle in low-energy sinks. Conclusion. When natural recovery is not feasible, capping may be an appropriate way to reduce bioavailability by minimizing contaminant contact with the benthic community. The efficacy of capping needs to be monitored, not only to ensure that risks are reduced, but also to gather data that can be used to advance the state of practice. The appropriate use of capping might be advanced if it were viewed as a permanent solution in the Superfund context. In situ immobilization and the chemical treatment of contaminated sediments have not been demonstrated successfully in the marine environment, although the concept is attractive because the cost of sediment removal would be avoided. In situ chemical treatment would be complicated by the need to isolate sediments from the water column during treatment, by inaccuracies in reagent placement, and by the need for long-term follow-up monitoring. Other constituents in this sediment (e.g., natural organic matter, oil and grease, metal sulfide precipitates) could interfere with chemical oxidation. Immobilization techniques may not be applicable to fine-grained sediments with a high water content. Conclusion. Although there are conceptual advantages to in situ chemical treatment, considerable R&D will be needed before successful application can be demonstrated. Biodegradation has been observed in soils, in groundwater, and along shorelines contaminated by a variety of organic compounds (e.g., petroleum products, benzene, toluene and xylene, PCBs, polyaromatic hydrocarbons, chlorinated phenolics, pesticides). However, biodegradation in subaqueous environments

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--> presents a number of significant microbial, geochemical, and hydrological problems and has yet to be demonstrated. Conclusion. Using bioremediation to treat in-place marine sediments, although theoretically possible, requires further R&D because it raises a number of significant microbial, geochemical, and hydrological issues that have yet to be resolved. Sediment Removal Technologies Efficient hydraulic and mechanical methods are available for the removal and transport of sediments for ex situ remediation or confinement. Most dredging technologies that can be used to remove contaminated sediments have been designed for large-volume navigation dredging rather than for the precise removal of hot spots. Promising technologies for precision control include electronically positioned dredge heads and bottom-crawling hydraulic dredges. The latter also may offer the capability of dredging in depths beyond the standard maximum operating capacity. The cost effectiveness of dredging innovations can best be judged through side-by-side comparisons to current technologies. Conclusion. Because of the high cost of ex situ treatment relative to dredging, dredges need to be made widely available that can remove sediments at near in situ densities and that have the capability for the precise removal of contaminated sediments, so that the capture of clean sediments and water can be limited, thus reducing the volume of dredged material requiring containment or treatment. Ex Situ Technologies Containment technologies, particularly CDFs, have been used successfully in numerous projects. A CDF can be effective for long-term disposal if it is well designed to contain sediment particles and contaminants and if a suitable site can be found. A CDF can also be a treatment or interim storage facility where sediments can be separated for varying levels of treatment and, in some cases, for beneficial reuse. Costs of CDFs are reasonable; in some parts of the country reusing CDFs may be cheaper than building new ones. Under some circumstances, CDFs can foster development in urban areas. Disadvantages of this technology include the imperfect methods of controlling pathways of contaminant release. Improved long-term monitoring methods are also needed. Conclusion. Research is needed to improve the control of contaminant releases, to improve long-term monitoring methods, and to improve techniques for preserving the capacity of existing CDFs.

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--> Contained aquatic disposal (CAD) is an appropriate method for managing contaminated sites in shallow waters where in situ capping is not possible and for containing moderately contaminated material from navigation dredging. Some advantages of CAD are that it can be performed with conventional dredging equipment and that the chemical environment surrounding the cap is not changed. The committee could not locate any useful estimates of actual costs. A disadvantage is the possible loss of small quantities of contaminated sediments during placement operations. Improved tools are needed for designing sediment caps and armor layers and for evaluating long-term stability and effectiveness. Conclusion. Construction of CADs on or near contaminated sites is likely to be acceptable, but the applications have not been explored fully. Research is needed to improve design tools and long-term monitoring methods and to control contaminant losses and determine their effects and associated risks. Scores of ex situ treatment technologies have been bench and pilot tested, and some may warrant broader testing in marine systems, depending on their applicability to particular problems. Ex situ treatment in general is more promising than the same treatment in situ because conditions can be controlled more effectively in a contained facility. Chemical separation, thermal desorption, and immobilization technologies have been used successfully but are expensive, complicated, and limited to treating certain types of sediments. Because of extraordinarily high unit costs, thermal and chemical destruction techniques do not appear to be cost-effective near-term approaches for remediating large volumes of contaminated dredged sediment. Conclusion. R&D on ex situ treatment technologies is warranted in the search for reasonable possibilities for the cost-effective treatment of large volumes of sediment. Bench and pilot testing of ex situ treatment technologies, and eventually full-scale demonstrations in marine systems, are needed to improve cost estimates, resolve technical problems, and improve treatment effectiveness. Ex situ bioremediation, which is not as far along in development as other ex situ treatments, presents an enormous number of technical problems, making it a costly option, at least initially, for treating contaminated sediments. However, if the technical problems can be resolved, ex situ bioremediation has the potential, over the long term, to provide cost-effective remediation of large volumes of sediment. Ex situ bioremediation has greater potential than the in situ approach because conditions can be controlled better in a contained facility. The technique has been demonstrated on a pilot scale with some success, but complex questions about how to engineer the system remain.

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--> Conclusion. In the search to develop reasonable, cost-effective treatments for large volumes of sediment, R&D on ex situ bioremediation is warranted The initial focus should be on developing and verifying methods for marine systems Remediation Technology Research, Development, Testing, and Demonstration It is unrealistic to expect dramatic breakthroughs that would substantially reduce the cost of large-scale ex situ treatment. In the near term, therefore, the optimal use of existing technologies—optimizing dredging and containment technologies through systems engineering, for example—appears to be the best way to enhance management effectiveness. Yet continuing efforts to identify, develop, and demonstrate new and improved remediation approaches are crucial to improving the management of contaminated sediments. Major technological challenges to be overcome include high costs, inadequate methods of predicting effectiveness, and the lack of extensive testing of many advanced treatment technologies, as well as the uncertainty associated with any innovative approach. The value of demonstration projects and of peer review of proposed technologies was confirmed by the Assessment and Remediation of Contaminated Sediments research and planning program in the Great Lakes. The development and use of innovative technologies might be promoted through side-by-side demonstrations with current technologies, an approach used in the EPA's Superfund Innovative Technology Evaluations program, which evaluates cleanup technologies for toxic and hazardous waste. Conclusion Additional R&D and demonstration projects are needed to improve existing remediation technologies and to reduce the risks associated with the development and use of innovative approaches to treating marine sediments. The development and wide use of cost-effective, innovative solutions would be advanced by (1) the peer review of proposals for R&D on new technologies for handling, containing, and remediating sediments and (2) the establishment of mechanisms for side-by-side demonstrations of new and current technologies. Recommendations for Improving Long-Term Controls and Technologies Based on the conclusions regarding the engineering costs of cleanup, in situ controls, sediment removal technologies, ex situ technologies, and remediation technology R&D, the committee offers the following recommendations, presented in order of priority: Recommendation. The Environmental Protection Agency and U.S Army Corps of Engineers should develop a program to support research and development and

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--> to demonstrate innovative technologies specifically focused on the placement, treatment, and dredging of contaminated marine sediments. Innovative technologies should be demonstrated side by side with the current state-of-the-art technologies to ensure direct comparisons. The results of this program should be published in peer-reviewed publications so the effectiveness, feasibility, practicality, and cost of various technologies can be evaluated independently. The pro- gram should span the full range of research and development, from the concept stage to field implementation. Recommendation. The U.S. Army Corps of Engineers and Environmental Protection Agency should develop guidelines for calculating the costs of remediation systems, including technologies and management methods, and should maintain data on the costs of systems that have actually been used. The objective should be to collect and maintain data for making fair comparisons of remediation technologies and management methods based on relative costs as well as their effectiveness in reducing risks to human health and ecosystems. Recommendation. The Environmental Protection Agency and U.S. Army Corps of Engineers should support research and development to reduce contaminant losses from confined disposal facilities and confined aquatic disposal, to promote the reuse of existing confined disposal facilities, and to improve tools for the design of confined disposal facilities and confined aquatic disposal systems and for the evaluation of long-term stability and effectiveness. Recommendation. The Environmental Protection Agency and U.S. Army Corps of Engineers should sponsor research to develop quantitative relationships between the availability of contaminants and the corresponding risks to humans and ecosystems. The overall goal should be to enable project evaluation using performance-based standards, specifically the risk reduction from in-place sediments; disturbed sediments; capped sediments; confined disposal facilities and confined aquatic disposal; and sediments released following physical, chemical, thermal, and biological treatments. Recommendation. The Environmental Protection Agency and U.S. Army Corps of Engineers should support the development of monitoring tools to assess the long-term performance of technologies that involve leaving contaminants in or near aquatic environments. Monitoring programs should be demonstrated with the goal of ensuring that risks have been reduced through contaminant isolation. IMPROVING PROJECT IMPLEMENTATION Improvements in decision making and remediation technologies would go a long way toward ensuring the cost-effective management of contaminated

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--> sediments, but assorted practical issues also need to be addressed to remove constraints on project implementation. First, responsibilities for source control need to be allocated fairly. Second, improved site assessment capabilities need to be developed and implemented to enhance overall cost effectiveness. Third, appropriate interim controls need to be used to reduce high risks until long-term solutions have been found. Fourth, incentives are needed to encourage the beneficial reuse of contaminated sediments; this would promote public acceptance, cost effectiveness, and address the problem of the shortage of disposal space. Responsibility for Source Control By commercial necessity, ports are located in quiescent waters, which are also natural sediment traps. Because accumulations of sediment interfere with deep-draft navigation, ports need to dredge periodically If the sediments to be dredged are contaminated, then ports are responsible for sediment placement and any necessary remediation. The suggested revisions in cost-sharing formulas for dredging and placement projects would relieve some of the burden on ports but would not address the issue of source control. Upstream generators of contaminants often cannot be identified or held accountable, leaving ports to manage the problem. States, which benefit economically from dredging and which customarily engage in watershed management, could assume some of the responsibility for source control if they are not already in charge of ports. Under the CWA (§303), the EPA and the states set total maximum daily loads for waterway segments and develop local allocations for sources of pollution in an effort to control water pollution. This approach, although it might be difficult to implement, could be expanded to address sources of sediment contamination. To foster such an approach, congressional initiatives (i.e., CWA reauthorization legislation) requiring watershed planning and management to control sources of water pollution could take into consideration upstream contributions to downstream sediment. In addition, government regulators and ports could explore all available legal and enforcement tools for forcing polluters to bear a fair share of cleanup costs. Conclusion Ports bear an unfair share of the responsibilities for the remediation and placement of contaminated sediments; project implementation could be facilitated by transferring the burden for source control to states (where applicable) and polluters. Site Characterization Needs and Technologies Site assessments need to be comprehensive and accurate enough to define contamination chemically and geographically. Inaccurate or incomplete assessments can leave areas of unidentified contamination that continue to pose unmanaged

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--> risks. Another compelling argument for accurate site assessment is the need to control remediation costs; precise site definition is necessary to facilitate the removal of only those sediments that are contaminated, thus reducing the volume of sediment that requires expensive remediation. But site assessment is also expensive The challenge lies in selecting the technique(s) and level of detail appropriate for the management phase and site in question. In a systems approach to sediment management, overall cost effectiveness is maximized when the accuracy of the site assessment is matched to the precision of the dredging equipment. However, the high costs of physical coring and sample testing (the most common site characterization approach) hinders precise definition of either horizontal or vertical contaminant distributions, often leading to the removal and "remediation" of large quantities of "uncontaminated" sediments at unnecessarily high costs. Conclusion New and improved techniques are needed to reduce the costs and improve the precision of site assessment. Acoustic profiling helps define the thickness and distribution of disparate sediment types Because contaminants tend to be associated with fine-grained material, acoustic profiling may provide for the cost-effective, remote surveying of contaminated sediments, thereby increasing the precision and accuracy of site assessment Additional R&D is needed, however. Meanwhile, chemical sensors used for soil and groundwater site assessments are being adapted for marine use Examples include X-ray fluorescence for the detection of metals in sediments and fiber-optic chemical sensors. Conclusion Remote-sensing technologies, including rapid and accurate sensors, could reduce the costs and improve the precision of site assessments. Interim Controls The use of interim controls may be advisable when sediment contamination poses an imminent danger and an immediate risk reduction is required More complete remediation solutions usually require considerable time to implement (3 to 15 years according to the committee's case histories). Identifying an imminent hazard is usually a matter of judgment, but in general an imminent hazard exists when contamination levels exceed a threshold level by a significant amount. Both administrative interim controls (e.g., signs, health advisories) and structural controls have been used, and additional structural controls, such as CDFs for temporary storage, appear promising. However, few data are available concerning the effectiveness of interim controls because few have been used, and even fewer have been evaluated.

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--> Conclusion Although few data are available concerning the effectiveness of interim controls, a number of measures appear to be practical and are likely to reduce risk to some (albeit unknown) degree. Other advantages include low cost and ease of implementation. Promotion of Beneficial Uses Dredged material has been used for many beneficial purposes, including the creation of islands for seabird nesting, landfills for urban development, and wetlands, as well as for beach nourishment and shoreline stabilization. The policy focus and most of the experience has been with clean sediments, but the beneficial reuse of contaminated sediments is both possible and worthwhile. Reuse can provide alternatives to increasingly scarce disposal sites while making management plans more attractive, or at least palatable, to stakeholders. Some contaminated sites have been successfully transformed into wetlands, and research is under way on the safe use of contaminated sediments for various purposes, including "manufactured" topsoil and landfill covers. However, funding for this type of research is limited, and technical guidelines have yet to be developed. Other barriers include the USACE policy of selecting lowest-cost disposal options with little regard for the possibilities of beneficial use and disputes over whether the incremental costs of beneficial use should be borne by the project proponent or the beneficiary. Conclusion The beneficial use of dredged contaminated material, although constrained by both the contamination and the poor structural properties of most contaminated sediments, can provide much-needed disposal alternatives and enhance the social acceptance of a project. Recommendations for Improving Project Implementation Based on the conclusions regarding source control, site characterization, interim controls, and the beneficial use of contaminated sediments, the committee offers the following recommendations, presented in order of priority: Recommendation. The U.S. Army Corps of Engineers should revise its policies to allow for the implementation of placement strategies that involve the beneficial use of contaminated sediments even if they are not lowest cost alternatives. In addition, regulatory agencies involved in contaminated sediments disposal should develop incentives for and encourage implementation of beneficial use alternatives. Recommendation. Funding should be continued for research and development of innovative beneficial uses for contaminated sediments and the development of

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--> technical guidelines and procedures for environmentally acceptable, beneficial reuse. Recommendation. Federal and state regulators, as well as ports, should investigate the use of appropriate legal and enforcement tools to require upstream contributors to sediment contamination to bear a fair share of cleanup costs. Recommendation. The Environmental Protection Agency and U.S. Army Corps of Engineers should conduct joint research and development projects to advance the state of the art in site assessment technologies. Objectives should include the identification and development of advanced survey approaches and new and improved chemical sensors for both surveying and monitoring. Recommendation. The U.S. Army Corps of Engineers should support demonstrations of innovative site assessment technologies. Remote sensing technologies should be demonstrated in an integrated survey operation at a major contaminated sediment site The project should demonstrate the capability of accurately defining a hot spot or larger critical area that requires either in situ treatment or accurate removal for ex situ treatment or placement.