Contaminated Sediments in Ports and Waterways Cleanup Strategies and Technologies (1997) / Chapter Skim
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2 Making Better Decisions: A Conceptual Management Approach
2 Making Better Decisions: A Conceptual Management Approach
Pages 30-43
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From page 30... ...
CONCEPTUAL VIEW OF THE MANAGEMENT OF CONTAMINATED SEDIMENTS To provide a framework for a systematic analysis, the committee developed a conceptual overview of the process for managing contaminated sediments (see Figure 2-1)
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For more detail on implementing the management plan, see Figure 5-1.
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As discussed in Chapter 1, the two fundamental driving forces are dredging, which is required to meet port and harbor navigation requirements, and environmental cleanup, which is required to reduce contaminant levels to a specific value. The preliminary site assessment begins with defining the degree and distribution of contamination, as well as justifying the consideration of taking appropriate actions.
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From page 33... ...
The fundamental issue to be addressed is how best to allocate scarce resources using an integrated set of tools. The latter part of this chapter examines analytical tools -- risk analysis, cost-benefit analysis, and decision analysis -- for examining trade-offs and arriving at a management plan.
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Systems Approach to Risk-Based Management To implement a management plan, a systems framework is needed for the engineering feasibility studies, the design, and the optimization of selected remediation technologies. Systems engineering is widely used in the design of complex technological processes to ensure that the various subsystems function together smoothly and achieve optimum overall effectiveness.
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These tools include risk analysis, cost-benefit analysis, and decision analysis. Risk analysis involves the extended application of risk assessment techniques, which typically are used only to assess the severity of inplace contamination.
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Thus, there are significant opportunities for improving and extending the application of risk analysis in the contaminated sediment context. The importance of risk analysis reaches beyond the issues just discussed because the results of risk assessments are essential elements in the cost-benefit analysis and the decision analysis.
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Three types of costs are involved in contaminated sediments cases: dollar costs of remediation and cleanup, dollar costs of foregone port services, and environmental costs. None of these costs can be measured precisely.
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The assessment of sediment quality is a hazard assessment intended to determine whether the exposure of aquatic biota to a sediment will cause an increase in the incidence of adverse, unacceptable effects. To supple ment effects-based testing, the EPA also is developing sediment quality criteria (SQC)
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The SQC approach advocated by the EPA for estimating the potential risk posed by contaminated sediment uses equi librium partitioning modeling to predict pore water concentrations of non polar organic compounds. These predicted pore water concentrations are then compared to chronic water quality criteria as an effects thresh old.
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However, the extensive cleanup of contaminated sediments tends to become increasingly costly as the concentration of contaminants declines. Furthermore, the social gains from cleanup tend to increase more slowly as the contaminant concentration declines.
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However, because decision analysis is technical in design and involves complex computations, it will take some time and effort for stakeholders to gain confidence in the approach. Remediation of contaminated sediments tends to be expensive and arduous, so any approach that helps expedite corrective action and resolves environmental controversies fairly and cost effectively could prove valuable.
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Decision analysis also can serve as a consensus-building tool by enabling stakeholders to explore the subjective elements of problems and, perhaps, find common ground. However, because it is technical in design and involves complex, albeit logical, computations, decision analysis is probably worth the effort only in exceptionally complicated and contentious situations in which stakeholders are willing to devote the time to gain confidence in the approach.
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From page 43... ...
1991. Technical basis for establishing sediment quality criteria for nonionic chemicals using equilibrium partitioning.
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