Contaminated Sediments in Ports and Waterways Cleanup Strategies and Technologies (1997) / Chapter Skim
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6 Conclusions and Recommendations
6 Conclusions and Recommendations
Pages 154-172
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From page 154... ...
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 decisionmaking 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.
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From page 155... ...
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.
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From page 156... ...
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.
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From page 157... ...
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.
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From page 158... ...
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.
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From page 159... ...
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.
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From page 160... ...
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.
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From page 161... ...
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.
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From page 162... ...
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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From page 163... ...
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)
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From page 164... ...
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.
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From page 165... ...
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.
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From page 166... ...
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.
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From page 167... ...
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.
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From page 168... ...
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.
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From page 169... ...
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.
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From page 170... ...
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.
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From page 171... ...
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.
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From page 172... ...
The U.S. Army Corps of Engineers should support demonstrations of innovative site assessment technologies.
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