islandsailingclub.co.uk/libraries/417/22.php 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. 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. 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.
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. 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.
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. 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 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.
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.
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. Three approaches can be applied to inform and improve decision making about contaminated sediments, particularly with respect to weighing the risks,.
The application of these approaches requires time and training. 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. 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.
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. 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.
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. More extensive use of appropriate methods for cost-benefit analysis have the potential to improve decision making. 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.
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. In addition to the suggestions for statutory changes that have already been made, the committee makes the following recommendations.
The Environmental Protection Agency and the U. 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. 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.
To facilitate the application of decision-making tools, the Environmental Protection Agency and U. 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.
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. 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. 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. Overall, the uneven state of the art suggests that technologies need to be selected, combined, and optimized using a systems engineering approach. Although 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.
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. Reducing volume i. 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. The data are inconsistent with respect to the types of costs included and the units of measure e. 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.
Contaminated Soils, Sediments and Water: Successes and Challenges, Volume 10 contains a valuable collection of success stories (and challenges) in the. Contaminated Soils Volume 9 contains 38 technical papers, covering a wide range of environmental issues. Volume discussion includes: Part I Bioremediation;.
Although the lack of reliable cost data does not preclude project planning, better cost information would contribute to sound decision making. 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.
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. 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. 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.
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. Immobilization techniques may not be applicable to fine-grained sediments with a high water content. Biodegradation has been observed in soils, in groundwater, and along shorelines contaminated by a variety of organic compounds e. However, biodegradation in subaqueous environments.
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. 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.
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. Under some circumstances, CDFs can foster development in urban areas. Each brought together scientists and engineers who are developing sensor technologies for environmental applications, and end-users.
The participants addressed important topics such as monitoring environmental and remediation processes, simultaneous measurement of multiple parameters, definition of emerging monitoring tasks, new parameters for sensor application, calibration and reference methods, and sensors to meet evolving demands. The sensor instruments were used on site to measure environmentally sensitive parameters in soil, sediments and river waters.
Promising results were obtained with measurements of heavy metals, calcium, chloride, general toxicity and genotoxicity. The speed of data production was fast enough for daily decision making. Three workshops and two practical meetings were held. Two specialised working groups were activated.
Virotec's senior management and operational staff have built a tremendous amount of experience in complex waste and remediation projects over the last 20 years always achieving a positive outcome. Wastes are periodically tilled to aerate the waste. 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. Outreach to Stakeholders and Consensus Building. Several projects have been initiated to better understand the occurrence, fate and transport of PFASs; a description of the Statements of Need and related projects can be found in the overall program description here. A key factor in determining the utility of a remediation technology is cost.
Collaboration between many individual European groups and also with networks was stimulated. Publications were produced and presentations were made to scientific and user groups. Project objectives: The overall objective is to enhance the development of chemical sensors, biosensors and biomimetic systems for practical applications in the abatement of water pollution from contaminated land, landfills and sediment.
Paths will be identified to resolve the most effective sensor systems for use in monitoring multiple pollutants contaminating water, soil and sediments and for use in site management in order to protect g round and surface water from pollution. Proceedings Only those asterisked are still downloadable.