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Summary
Pages 1-15

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From page 1...
... From a regulatory standpoint, contaminated sediments are challenging to manage. The Superfund program,1 administered by the U.S.
From page 2...
... The techniques include removing the sediments from the aquatic environment (for example, by dredging) , capping or covering contaminated sediments with clean material, and relying on natural processes while monitoring the sediments to ensure that contaminant exposures are decreasing, or at least not increasing.
From page 3...
... In brief, the committee's charge requests an evaluation of the expected effectiveness of dredging of contaminated sediments at Superfund megasites. The committee was asked to consider such aspects of dredging as short-term and long-term changes in contaminant transport and ecologic effects.
From page 4...
... .3 Various sites were examined, including full-scale dredging projects, pilot studies at sites, and dredging projects within a large-scale remediation effort. Conclusions The committee concluded that dredging is one of the few options available for the remediation of contaminated sediment and that it should be considered, with other options, to manage the risks that the contaminated sediments pose.
From page 5...
... Residual contamination and contaminant release are inevitable during dredging and should be explicitly considered in estimating risk reduction. Some site conditions and dredging practices can limit the amount of residual contamination remaining after dredging and can limit contaminants released into the water column.
From page 6...
... EPA should centralize sediment-related resources, responsibility, and authority at the national level to ensure that necessary improvements are made in site tracking, in the implementation of monitoring and adaptive management, and in research to examine the relationship between the remedial actions, site conditions, and risk reduction. measures necessary to evaluate risk over time,4 dredging may have occurred in concert with other remedies or natural processes that affect risk, insufficient time has passed to evaluate long-term risk reduction, and a systematic compilation of site data necessary to track remedial effectiveness nationally is lacking.
From page 7...
... Residual contamination after dredging can result from the incomplete removal of targeted sediments or the deposition of sediment resuspended during dredging. Residual contaminated sediments hamper the ability to achieve desired cleanup levels and are exacerbated by site conditions like obstructions in the dredging area and impenetrable or uneven formations underlying the contaminated sediments.
From page 8...
... Backfilling and capping can be used following dredging to manage residual contaminated sediments. Contracting mechanisms can be used to encourage a focus on specified cleanup levels and remedial-action objectives instead of on attaining mass removal targets.
From page 9...
... It is impossible to evaluate effectiveness in the absence of sufficient baseline data and appropriate reference sites. Monitoring needs to be conducted to confirm not only that desired cleanup levels have been met, but that they result in risk reduction.
From page 10...
... Fish-tissue monitoring for contaminants is useful for indicating risks to the health of people and other piscivorous species, particularly if long-term monitoring trend data exist. However, linking changes in fishtissue concentrations to remedial actions can be problematic, because fish are mobile and can be exposed to offsite conditions.
From page 11...
... IMPROVING FUTURE DECISION-MAKING AT SUPERFUND MEGASITES Conclusions The historical perspective and hindsight gained from the committee's retrospective analysis of sediment sites provide an opportunity to derive common lessons and to improve on the manner in which environmental dredging is planned and implemented. It is important that this type of review be on-going and be part of a shared experience among regulators, practitioners, and the public.
From page 12...
... Thus, the process for remedy selection at large, complex sediment megasites needs to allow more adaptive site investigation, remedy selection, and remedy implementation. Second, improved risk assessment that specifically considers the full range and real-world limitations of remedial alternatives is needed to allow valid comparisons of technologies and uncertainties.
From page 13...
... • EPA should compare the estimated net risk reductions associated with different remedial alternatives, taking into account the realworld limitations of each approach (such as residuals and resuspension) in selecting site remedies.
From page 14...
... EPA and its federal part ners should develop a research and evaluation strategy to under stand the risk reduction attained by various technologies under vari ous site conditions and the associated uncertainty. EPA's efforts should focus on moving forward with remedies at sites while testing and learning with each new pilot test or remedy to determine what works, what does not work, and why.
From page 15...
... Summary 15 Many of the sites are vast and expensive, and it is worthwhile to invest time and resources now to ensure more cost-effective remedies in the future. That focus is warranted if the country is to make the best use of the billions of dollars yet to be spent on remediation.


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