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FINDINGS AND RECOMMENDATIONS EXTENT OF CONTAMINATION Findings Many marine s ites are known to contain sediments with high levels of anthropogenic chemicals or to have altered biological characteristics. However, there are no generally accepted definitions of contamination that trigger consideration of remedial action. The working definition of contaminated sediments used in this report is those which contain chemical substances at concentrations that pose a known or suspected environmental or human health threat. The sites that require the most urgent attention are those reservoirs of contamination that affect regions or that have the most severe impacts on health and the environment. Pending revisions of the Superfund Hazard Ranking System will facilitate the assessment and prioritization of human health and ecological risks associated with contaminated sediments. Many contaminated marine sediments are located along all coasts of the contiguous United States, both in local "hot spots" and distributed over large areas. Some of these sites, but not many, have been well characterized. Existing data on individual sites and their contamination vary widely in content and organization. Assessments using available data have been conducted on the national extent of contamination and have identified a partial picture of the total contaminated sediment problem. These studies have shown that a wide variety of contaminants are found in sediments, including heavy metals, polychlorinated biphenols (PCBs), DOT, and polynuclear aromatic hydrocarbons (PAHs). However, no federal agency has assumed the full responsibility of establishing a national inventory of sites with contaminated sediments or a comprehensive assessment of the extent of contamination on a national basis. A number of state and federal agencies collect data for different purposes and use different approaches. However, sediment contamination data collected for one purpose may be of little relevance or applicability for another because of parameters measured, methods used, or temporal and spatial scales designated. For example, sediment data assembled for setting regulatory criteria or for following national or regional trends may be of little value in detecting site-specific problems or in defining site-specific remediation requirements. 4
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5 This can be illustrated by N()AA's National Status and Trends Program. As part of this program, NO M has acquired sediment data from approximately 200 sites around the coasts of the United States (see Robertson and O'Connor, pages 47-62~. This information is used to determine broad national- and regional-scale status and trends in sediment contamination levels. However, the network of stations is not sufficiently dense to allow the data to be used to set clean-up priorities or to make site-specific judgments. Indeed, the NOAA program intentionally excluded from its database, sampling stations deemed to be reflective of localized hot spots rather than of broad regional contamination trends. In short, care should be exercised to ensure that data generated by monitoring programs are not inappropriately used beyond the limits or intent of the original monitoring program. At present, there are no generally accepted and validated sampling techniques, testing protocols, or classification methodologies for determining sediment contamination. A certain uniformity in parameters measured and data reported is desirable to facilitate intercomparisons. This must be accomplished by setting some national standards, criteria, or guidelines. In general, efforts by states to address potential marine sediment contamination are diffuse and not well focused. For example, most state water quality agencies focus on discharges and impacts to the water column. Thus, little effort is being expended by state agencies on identifying and remediating contaminated marine sites. State hazardous waste agencies are, in most cases, directing their efforts to upland areas so their involvement in marine sediments problems is limited. Recommendations Search for Contaminated Sites The location and extent of contaminated marine sediments have not been comprehensively assessed on a national basis to identify site-specific remediation targets. The federal government should initiate such a program to delineate areas with contaminated sediment. The objective should be neither detailed mapping nor duplication of NOAA's regional National Status and Trends Program. In regions of concern, or in areas of known hot spots, special attention should be directed to identifying and characterizing specific contaminated sites. The search for new sites or the reclassification of known sites should proceed concurrently with remedial action. Utilization of Federal, Regional, and Local Expertise Due to the variability in environmental conditions among sites, well-info``ued local specialists provide a critical complement to our national expertise. Neither federal , regional, nor local managers can
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6 operate effectively in a vacuum. Managers at all levels of government should interact and cooperate and remain receptive to the expertise and concerns of other specialists in assessing or remediating contamination at a particular site. Coordination of Efforts An interagency technical committee, including nongovernmental as well as state and federal experts, should be established to evaluate existing and emerging data on sediment contamination. This committee would assemble data, prepare reports, and make recommendations as to the need for and direction of sediment research and monitoring activities, including sediment and sampling assessment methodologies. The objective of the committee would be to focus the limited resources on the most needed research and monitoring, reduce redundancy, and help eliminate improper uses of data. CLASSIFICATION METHODOLOGIES Findings A variety of biological and chemical sediment classification methods are available. Individually or in combination, they attempt to systematically characterize marine sediments with elevated levels of contaminants, and correlate such concentration increases with adverse biological effects. With one possible exception (the acute amphipod bioassay), none of these techniques are routinely used and each has its limitations. Indeed the cost and complexity of a number of these tests virtually ensures that they will be used routinely only at large sites. Several contaminated sediment classification techniques were examined by the committee: sediment bioassays, sediment quality triad approach, apparent effects threshold technique, and equilibrium partitioning. Each technique is discussed in detail in a presented symposium paper (in this volume) and some of the advantages and disadvanges of each (for remedial action screening and sediment quality criteria development) are set forth in Table 1. From a remedial clean-up standpoint, the most useful sediment testing and classification procedures would be those that are simple and inexpensive, with rapidly available test results. If sediment quality criteria methodologies are adopted by EPA, a routine basis for establishing the presence of unacceptably high levels of sediment contaminants may be available. The design and implementation of remedial action for contaminated sediments are likely to be delayed and frustrated unless one can readily determine "how clean is clean." Development of an interim working methodology to establish such a criterion would alleviate the delay.
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TABLE 1 Assessment of Sediment Classification Methodologies Classification method Advantages Disadvantages Bioassay Sediment Quality Triad · follows toxicologi- cal methods developed for water quality criteria · a direct measure of sediment toxicity · does not require identification of individual contaminants · does not assume a specific route of uptake · acute results available quickly · established test procedures in use for dredged material characterization · based on a combina- tion of laboratory and field data indicating effects of actual contaminated sediments · based on observed biological effects · does not assume a specific route of chemical uptake · applicable to complex mixtures requires development of standard chronic bioassay methodologies · may be more costly than some chemical analyses · difficult to translate laboratory results to natural conditions · difficult to determine chemical effects · does not address human health impacts · results of chronic tests may not be timely · may not identify causative contaminants · limited by the availability of existing data or by the ability to collect large amounts of new data · available data may be of highly variable quality · difficult to translate laboratory results to natural conditions · does not address human health impacts · may not identify causative contaminants r
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8 TABLE 1 ( Continued) Classif ication methods Advantages Disadvantages Sediment Quality Triad (cons . ~ Apparent Effects Threshold · indicators are not independent; c ovary with grain size and organic carbon content · potentially not comparable between geographic locations · does not consider chemical bioavailability from site to site · uses existing data (from field and laboratory; e.g., Sediment Quality Triad) · applicable to all chemicals and all biological effects · most useful for prioritizing contaminated areas within a large site · based on observed biological effects · does not assume a specific route of chemical uptake · applicable to complex mixtures r · limited by the availability and quality of existing data · varies with choice of biological effects indicator · relies on correlations/ may not identify causative contaminants · potentially not comparable between geographic locations · may be both over- and under-protective difficult to translate laboratory results to natural conditions · does not address human health impacts · multicompound interactions not accounted for · Indicators are not independent; c ovary with grain size and organic content
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9 TABLE 1 ~ Continued) Classification method Advantages Disadvantages Equilibrium Partitioning · provides a chemical specific criterion · utilizes large toxicological data base incorporated in water quality criteria and other toxico- logical endpoints · relies on well- developed partitioning theory · accounts for the bioavailability of the chemical interest · provides a standard basis for comparison within and among sites · where data are available allows quick and inexpensive characterization · incorporates a built-in "how clean is clean" standard · is a direct measure- ment of sediment characteristics · can be readily incorporated into existing regulatory frameworks ~ does not consider complex mixtures and chemical interactions ~ currently limited to hydrophobic neutral organic compounds · does not address human health impacts · limited to contaminants for which both water quality criteria (or other suitable toxicological endpoints) and sediment- water partitioning coefficients are available 0 relies on KoCa measurements which are often variable · does not account for contaminant uptake by ingestion of particles or direct absorption/ adsorption from sediments · sediment and water may not be at equilibrium with respect to contaminant concentration · does not use toxico- logical data derived from the sediment of interest · assumption of constant- bioaccumulation factor for various contaminants and organisms is questionable aKOc--carbon normalized sediment-water partition coefficient.
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10 Although a variety of methods for assessing contamination are available, there is no single method that is widely accepted and~some may be more suited to a particular situation than others. Approaches that develop single numeric criteria often do not provide sufficient data for assessing the overall significance of contamination at a site. A number of approaches may be needed to evaluate the significance and extent of contamination at any given site. Recommendations Improved Methodologies In order to ensure that decision making is informed and scientifically based, continued research and use of assessment methodologies should provide information to determine · a range of concentrations of chemicals in sediments that will result in biological effects, and · whether in-place sediments are causing biological impacts. Additionally, increased efforts should be made to refine methods for sediment classification to be used by regulatory agencies. Tiered Testing A tiered approach to the assessment of contaminated sediments should be used. The approach would progress from relatively easy and less expensive (but perhaps less definitive) tests to more sensitive methods as needed. RISKS TO HUMAN HEALTH AND THE ECOSYSTEM Findings The most significant human health risk associated with marine sediment contamination may be ingestion of contaminated fish and shellfish. Many compounds, such as some polyaromatic hydrocarbons (PAHs), may be readily metabolized by enzymatic systems in higher aquatic organisms such as fish, although there is uncertainty about whether they are detoxified. Some invertebrates, such as bivalve mollusks, have only a limited ability to metabolize PAHs and tend to accumulate them to higher concentrations and retain them more. Therefore, consumption of these animals may be a source of human exposure. Trace metals are not degraded and may be bioaccumulated by aquatic organisms and then transferred to humans via consumption of seafood. Reports of "fin rot" and tumors in finfish, particularly bottom-feeding fish in Puget Sound and the New York Bight in recent years, provide further evidence that there may be substantial risk to the ecosystem and potentially to human health due to the contamination
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11 in marine sediments. Although there is general consensus that seafoods present a route of transfer of contaminants to humans from contaminated sediments, the extent of risk that is posed is unknown. In addition to the carcinogenic nature of many of these contaminants, reproductive impairments and other sublethal effects in humans are concerns that require increased attention. Risk assessments of these latter endpoints have not been conducted. Furthermore, inadequate attention has been given to mammalian studies of the long-term chronic effects of ingesting contaminated fish and shellfish. Epidemiological studies of human populations living near contaminated sediment sites also have been under-emphasized. Assessment of the ecological effects resulting from sediment contamination is an area that needs additional study. This is especially true for soft-bottom communities in trying to correlate ecological impacts with chemical- specific factors . Accumulation of contaminants in marine sediments can cause death, reproductive failure, growth impairment, or other detrimental changes in the organisms exposed to these contaminants. Such changes can impact not only individuals but also entire benthic populations and communities. Both localized and widespread contamination has in the past resulted in significant population and community changes. Typically this involves the elimination of less tolerant species and an increase in more tolerant species. Such changes can have far reaching, long-term effects on a given ecosystem. Generally, those species that are eliminated have not received the attention they deserve in the assessment of ecological effects. Furthermore, the technical capability has not evolved for interpreting population and community responses in relation to specific chemicals. Sublethal and chronic effects of contaminants on the marine ecosystem are a significant environmental concern. However, at the present time there are no widely accepted sublethal and/or chronic effects tests available. Much research is being conducted on tests for growth, reproduction, or biological abnormalities . Interpretation of such tests is often difficult and there are few established criteria available to j udge the sublethal and chronic effects of contaminants on the marine ecosystem. Recommendations Assessment of Risk Due to Contamination Although the assessment of human health risk is important, a more balanced approach requires greater emphasis on ecosystem impacts. This will require regulatory agencies to utilize new assays being developed to detect and gauge the effect of contamination on physiology (assays such as immune suppress ion, enzyme induction, and DNA adduct formation), life stage impacts (using parameters such as reproductive success, growth, and recruitment), pathological effects, and changes in community structure.
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12 In terms of risks to human health, consideration should be given to conducting available retrospective human epidemiology studies of exposed populations in the development of an overall assessment and remedial plan. MOBILIZATION AND RESUSPENSION OF CONTAMINANTS Findings The decision to manage contaminated marine sediments in place or to remove and relocate them on land involves consideration of the potential for contaminant mobilization and release to the environment. There is a tendency for heavy metals in marine sediments placed in on-land disposal sites to desorb under changing geochemical conditions (such as decreased pH due to acid formation) and potentially allow chemicals to leach into groundwater. Organic chemicals found in marine sediments tend to maintain relatively constant solubility and mobility potential when disposed of on land. When contaminated sediments are excavated and placed in contact with the air, relatively low concentrations of volatile organics can contaminate the air. The most obvious difference in risks associated with on-land and aquatic disposal of contaminated marine sediments is the greater significance of food chain contamination as an exposure pathway in aquatic disposal. Estimates of both deposition rates and erosion rates are needed in order to decide whether to remove contaminated sediments. If natural sedimentation causes the rapid burial of contaminated sediments in place, then other remediation may not be needed. However, if the contaminated sediment is subject to resuspension and dispersion, in-place capping or removal may be necessary, even if the contamination is distributed over large areas or long distances. Where the environmental impact potential is severe (e.g., downstream shellfish beds or drinking water intakes) a significant erosion or resuspension potential may suggest the need for quick remedial or removal action while sediment contaminants are still relatively localized and concentrated. Our understanding of the transport of coarse-grained, noncohesive sediments is relatively well developed. Unfortunately, contaminants are most often associated with fine-grained cohesive sediments and the ability to forecast their behavior with confidence is very poor. Significant research is under way by the Army Corps of Engineers and the Environmental Protection Agency to try to define the sediment-water boundary layer conditions that limit the use of predictive models. With information concerning the strength of the currents, some general statements can be made concerning whether a site is likely to be one of scour or of deposition. However, the rates of either erosion or deposition cannot now be estimated from measured parameters. General statements are usually not an adequate basis for management decisions. A more complete understanding of the sediment transport processes for fine-grained cohesive sediments is needed.
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13 Present practice, based on state-of-the-art knowledge, is to employ empirical models. For example, several major studies have been conducted by the Corps of Engineers for Mississippi Sound in the Gulf of Mexico, Los Angeles and Long Beach harbors, and Chesapeake Bay. These investigations have attempted to modify and adapt three-dimensional models to site- specific conditions. Resuspension rate, settling velocity, deposition rate, critical erosion velocity, rate of consolidation, rate of biological mixing, and other variables must be empirically determined for each site. The relevant processes are described by direct measurements in the field to determine a set of empirical parameters that are then applied to the site. Measured site- specific data then provide the quantitative examples that are assumed to be typical of that site at all times. Although the models rely on highly empirical approaches, they are the best tools presently available for making predictions of sediment resuspension and transport. Empirical models for predicting the resuspension and mixing of contaminated sediments have serious limitations which include the following: 1. Relying on measurements made at a specific time and place under a particular set of conditions. There is no guarantee that the measured rates will be accurate if any of the conditions change. Small changes in the environment can lead to very large discrepancies between the empirical forecast and the actual phenomenon. As a result, the empirical models are accompanied by potentially large, and usually, unspecified uncertainties. In many cases, the magnitude of the uncertainties may be acceptable in the management decision if it is known with confidence. 2. Development of empirical models can be extremely costly. There are many types of data needed and the measurements have to be made at many locations over long time periods to improve confidence in the results . Additionally, measurements have to be made for every s ite of interest. This would not be a serious disadvantage if there were only a few contaminated sites. Unfortunately, there are many sites that need attention. Recommendations Contaminant Transport and Partitioning Continued and expanded support should be given to understanding the partitioning of contaminants among sediments, soils, water, organisms, and the atmosphere, as well as the transport of substances in the various phases. In
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14 Research in Sediment Transport To keep costs of modeling fine-grained sediment transport reasonable, models built on basic processes need to be developed. While empirical models continue to be used to reach management decisions, effort should be simultaneously directed to understanding the basic processes to be modeled and the validation of models in the field. Specifically, support should be expanded for research to determine the fundamental processes responsible for sediment cohesion and the factors controlling their resuspension. There is also a need to improve the reliability of estimates of both deposition and resuspension. Research programs in this area should be expanded and diversified. Tiered Response Strategy A tiered strategy is needed to address contaminated sediment problems in situations in which high erosion rates or resuspension potential may rapidly alter the distribution of contaminants and there is no time to carry out more detailed assessments. Problems in high-energy environments should be assessed promptly. CONTAMINATED SEDIMENT MANAGEMENT STRATEGIES Findings Although the dredged material management strategy developed by the Corps of Engineers may be relevant to severely contaminated sediments, it is important from a management standpoint to differentiate them from less contaminanted sediments. In particular, most highly sophisticated remedial technologies (i.e., those involving treatment or destruction of associated contaminants) are likely to be cost-effective only in small areas and for sediments with relatively high contamination levels. Sediment contamination problems often involve large volumes of sediment with relatively low contamination levels. As a result, some highly sophisticated technologies may be inapplicable or inefficient for remediating contaminated sediments. "No action" may be the preferred alternative in cases in which the remedy may be worse than the disease--e."., where dredging or stabilizing contaminated sediments results in more biological damage than leaving the material in place. Contaminants generally accumulate in depositional zones, and, if the source is controlled, new sediments will deposit and cap the contaminated material over time. In effect, no action alternatives in such cases may result in natural capping. Extensive preremediation studies, as practiced at very large sites (e.g., Commencement Bay, New Bedford Harbor, upper Hudson River) may not be practical at much smaller sites. Routine screening procedures and validated sediment assessment methods may be especially valuable in such cases. Large-scale remedial technologies are often not applicable
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to small sites for a variety of reasons. In such cases, regional sites or facilities may provide a means for handling sediments from several smaller s ites . There are existing management alternatives that have been effectively used for dealing with contaminated sites. 1. No action may be an acceptable option if the contamination degrades or is buried by natural deposition of clean sediment in a short period of time. 2. In-place capping may be a useful option if the sediments are not in a navigation channel or if groundwater is not flowing through the site. 3. Removal and subaqueous burial off-site may be a viable option, although the experience with this technique is limited to relatively shallow water (< 100 ft). Incineration seems to be viable only for sites with relatively small amounts of sediments containing high concentrations of combustible contaminants. . Other techniques to assist in remediation of contaminated sediment may be appropriate in special cases. Examples include a variety of sediment stabilization or solidification techniques, and biological and/or chemical treatment. Recommendations Dredged Material Management Strategy Additional evaluation should be conducted to determine the applicability of the Corps of Engineers' dredged material management strategy to more severely contaminated sediments. No Action No action should always be considered as an alternative strategy for minimizing biological damage. In using the no-action strategy as a form of natural capping of contaminated material, consideration should be given to the length of time it takes for contaminants to be isolated from the food chain. REMEDIAL TECHNOLOGIES Findings From a remediation standpoint, the most important factors are likely to be defining of the clean-up targets technical and cost feasibility, natural recovery estimates, and ability to distinguish and/or control continuing sources of contaminants. Dredging technology exists that is capable of greatly reducing turbidity and resuspension in connection with dredging of bottom
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16 sediments in most applications. However, because of legal (i.e., Jones Act) and practical restrictions that limit access to foreign-built vessels domestically, it may be difficult to secure access to this technology in the United States--except as equipment fitted onto U.S.-built vessels or supplied through U.S. subsidiaries of foreign dredging companies. U.S. government policies have not provided adequate encouragement to domestic firms to construct innovative dredges. Although silt curtains can prevent movement of sediment in the top two or three feet of water column, they allow movement of sediment under the silt curtain. Silt curtains cannot operate with currents faster than one knot and are ineffective in waves. Thus, the use of the silt curtains is confined to low-energy areas. Capping of contaminated sediments--whether in place, as mounds, or in subaqueous pits--in many cases offers a promising means of effectively isolating and containing associated contaminants. A potentially significant legal and policy issue is whether capping with clean sediments is to be deemed a preferred treatment approach under SARA, Section 121(b). On the one hand, capping can be done on site (which is favored over offsite transport) and it can "significantly reduce the . . . mobility of the hazardous substances, pollutants, and contaminants" present. On the other hand, it is not treatment in the usual chemical, biological, or physical sense, but rather containment or permanent storage. If capping materials are modified with the addition of carbon or other materials they may sorb contaminants and thus could more reasonably be defined as a treatment alternative. While widely applicable, there are practical limits to the feasibility of capping. Among the factors that may preclude or constrain the use of capping are water depth; low sediment density; high sediment water content; active erosional area; active navigational channel requiring periodic maintenance dredging; and the use of trawls, draglines, or oyster dredges, which would destroy the integrity of the cap. Although the sediment properties needed for an effective cap are not well-defined, both clay and sand have been used successfully. Attention must also be paid to any subsequent disturbance of the cap either by natural processes (e.g., storm erosion or bioturbation) or human activity (e.g., fishing). There are several examples of capping of dredged sediment mounds on subaqueous disposal sites. These provide very useful experience for guiding future decisions. There are, however, few general standard criteria for evaluating the likely success of a planned capping operation. Where capping is clearly feasible, prudence (and/or SARA) may dictate well-directed monitoring. Such monitoring can constitute a significant proportion of the total remedial action cost.
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17 Recommendations Source Control Source control measures must be cons idered in all cases, including no action. Federal and state regulatory agencies requiring remedial action should implement source control measures as a component of remedial action when applicable and appropriate. Use of financial incentives through strict liability for assessment costs, remedial actions, and damages also may play an important role in source control, provided that trustees make aggressive efforts to hold responsible parties liable for releases into the environment. Technology and Information Transfer Aggressive technology and information transfer mechanisms are needed to ensure that knowledge gained and lessons learned from all remedial actions are available and accessible to managers confronting new remediation problems at federal, regional, and local levels. Knowledge gained should be systematically compiled in guidance documents. Lessons learned regarding the feasibility of sophisticated remedial technologies under varying conditions of contamination severity and extent should be documented and made widely available to facilitate future decision making. Lastly, experience gained through the use of screening procedures at large sites should be distilled and generalized into routine methodologies for economically assessing smaller sites. Remediation and Navigational Dredging When possible, remediation projects should be designed to take advantage of existing navigational dredging activities that may already be authorized in conjunction with the Clean Water Act, Section 115 or Section 10/404. Remedial Technologies Research and development should be encouraged by the federal government to develop technology and equipment for efficiently removing contaminated sediments and to make it available in the United States. Foreign technologies should continue to be examined relative to their appropriateness in this country. Efforts to conduct and fund research and development as a partnership between government and industry should be encouraged. Use of Capping Although capping might not, in the strictest terms, be considered a remedial technology, it should not be ignored because it can play a valuable role in remediating contaminated sites.
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18 Well-focused Monitoring Monitoring programs should be well-focused on testing forecasts made during design of the remediation plan. To the extent possible, monitoring should be extended to remove uncertainties in the basic understanding of contaminated sediment behavior. For example, monitoring of capped areas might focus on changes of cap thickness, erosion around boundaries, and leakage of contaminants through the cap. REMEDIATION AND SOURCE CONTROL: ECONOMIC CONSIDERATIONS Findings Remedial actions are costly and become more expensive as additional levels of clean-up or treatment are pursued. The role of tradeoffs between possible technologies at and among sites must be considered, given the scarcity of funds to clean up contaminated sites and the potentially great number of sites. The use of benefit-cost analysis as part of the remedial action decision process would provide perspective on the issues involved. It would place investments in this area on the same footing as other public investments. However, difficulty in quantifying benefits from remedial actions in monetary terms makes reliance on benefit-cost analysis infeasible in a number of cases. Nonetheless, in light of the high cost of remedial actions, it is important that implicit (if not explicit) consideration be given to potential benefits before remedial actions are undertaken. Cost-effectiveness analysis is also a valuable technique for helping to guide clean-up efforts at and among sites when a decision to remediate has been made. However, to be applied correctly, both short- and long-term costs must be included, and costs must be estimated consistently for alternative actions at and among sites. The process of assessing the need for remediation and evaluating alternative remedial actions for a site appears to be excessively long and costly. In many cases, millions of dollars and several years are expended before a decision is made. If remedial action is excessively delayed, benefits may diminish over time. Removal of contaminated sediments can be very expensive, varying widely from several hundred thousand dollars to tens of millions of dollars. Data on 15 clean-up sites indicate that total clean-up costs can reach $500,000 to $1,000,000 per acre. This compares with iFor purposes of comparison, assume that a one-acre cleanup involved removing overburden to a depth of one yard, or a total of 43,560 yds3 of contaminated material. In that event, total cleanup costs would range from $11.50 to $23.00 per yd3. 2U.S. Congress Office of Technology Assessment . 1988 . Are we cleaning up? 10 Superfund case studies. Special Report OTA-ITE-362. Washington, D.C.: U.S. Government Printing Office.
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19 an average unit cost of navigation dredging of $1 to $2 per cubic yard of sediment dredged. The average unit cost of all dredging, both government and private, is estimated at $1.67 per cubic yard of material dredged. 3 Onsite incineration, one of the remedial measures proposed at various sites, is also very expensive. The estimates quoted are from $186 to $750 per cubic yard. 4 Recommendations Use of Benefit-Cost Comparisons In view of the high cost of remedial actions in most cases, greater use should be made of benefit-cost comparisons over ecologically relevant time periods in order to place investments in this area on the same economic footing as investments in other public proj ects . Cost-Effectiveness Analysis Cost-effectiveness analysis of alternative remedial actions should consider both short- and long-term costs. Comparisons at and among sites should be based on costs estimated using a consistent approach. Degree of Remediation In evaluating the degree of remediation to be conducted at a site, it should be recognized that incremental costs typically will increase rapidly as additional levels of clean-up are sought. Economic and Environmental Cons iterations The decision as to whether or not remedial actions are undertaken should be based on a balanced comparison of the anticipated environmental and public health benefits of actions with their costs, including possible environmental and health risks. Infeasible Remedial Options Clearly infeasible options should be eliminated at the outset, before alternative remedial actions are considered in depth. 3Pequegnat, W.E. 1987. Relationship between dredged material and toxicity. TERRA et AQUA 34. 40p. cit., no. 1.
Representative terms from entire chapter: