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21 ELR 10020 | Environmental Law Reporter | copyright © 1991 | All rights reserved Managing Contaminated Sediments in Aquatic Environments: Identification, Regulation, and RemediationW. Andrew MarcusEditors' Summary: The contamination of sediments in aquatic environments poses a direct threat to water quality, bottom-dwelling organisms, and animals feeding on those organisms. In recognition of the pervasive nature of this problem, several state and federal agencies are attempting to fashion guidelines for identifying, regulating, and cleaning up polluted sediments. This Article summarizes those efforts in light of the key regulatory and scientific dilemmas faced by agencies attempting to manage such sediments. Specifically, it provides a brief synopsis of the history and extent of contamination problems in the United States and the need for management strategies. A major problem in developing these management strategies has been defining what constitutes a "clean" or a "polluted" sediment. The Article summarizes historical and contemporary approaches to identifying polluted sediments and discusses hydrologic, biochemical, and regulatory problems involved with each methodology. It then examines the legal bases for federal management of aquatic sediments and what practitioners need to know when navigating current hazardous waste and water issues. The Article concludes with a discussion of the techniques for mitigating contamination in aquatic sediments and the difficulties practitioners and regulatory personal must address when implementing these techniques. W. Andrew Marcus is an Assistant Professor in the Department of Geography, University of Maryland at College Park. He received his Ph.D. in geography from the University of Colorado, his M.A. in geography from Arizona State University, and his B.S. in geology from Stanford University. His research has focused on water policy and human impacts on runoff, erosion, and contaminant transport in sediments. Dr. Marcus teaches classes on environmental systems, geomorphology, hydrology, field research techniques, and water resources policy. The author wishes to thank Mr. Chris Zarba for his critical review and comments. Problems associated with the contamination of aquatic sediments have been recognized for at least 60 years,1 although widespread concern did not surface until the late 1970s. Early efforts to reduce pollution in aquatic systems focused on reducing point-source discharges to surface waters, which deflected attention from the threat posed by already polluted sediments. Public and scientific pressure to regulate sediments erupted after well publicized incidents of sediment damage to fisheries and wildlife, such as polychlorinated biphenyl (PCB) contamination in the Hudson River2 and a wide variety of pollutants in Puget Sound3 and Great Lakes4 sediments. This heightened concern has resulted in research documenting the processes contributing to sediment pollution, the extent of this pollution, and problems associated with sediment contamination.5 Contamination of Aquatic Sediments and Environmental Consequences Risk-posing aquatic sediments are generated in three ways. In the most obvious pathway, contaminated sediments are created directly, as with sewage sludges or fly ash from power plants. In another pathway, solids with naturally high concentrations of a contaminant are altered so that the pollutant can be more easily released to the environment. This most commonly occurs in mining operations, where heavy metal-bearing rocks are milled into very fine particles for extraction purposes.6 Only a portion of the total metal content is removed in the refining process, which leaves substantial quantities of metal in the fine grained sediments. When these sediments are disposed of, usually in tailings piles, they can introduce metal contamination to points far from the original source through groundwater percolation, windblown dispersion, and erosion and transport by streams. The third and perhaps most prevalent pathway of sediment contamination is via the sorption of dissolved substances onto sediment surfaces.7 A large portion (often the majority) of organic and inorganic pollutants in aqueous solution will migrate to sediment surfaces, particularly if the sediments have a large clay component or a high organic content. Processes of atmospheric deposition and water-borne contamination can thus pollute sediments that are tens and even hundreds of kilometers from the original source. Once contaminated, aquatic sediments pose a particularly pernicious form of pollution, acting as a long-term reservoir that can introduce toxins to the environment far from the original source and long after discharge activity has shut down. Pollutants in aquatic sediments cause environmental damage by releasing toxins to surrounding waters, directly contaminating flora and fauna that live within and ingest the sediments, and by introducing toxins into the food chain, which are then transferred up the trophic ladder to higher organisms, including humans. The releaseof sediment-bound toxins into the water column is particularly notable during storms, when increased flows and turbulence place bottom sediments in suspension, promoting rapid chemical fluxes between sediments and the surrounding water. The introduction of these slugs of contaminated sediments into the water column can have immediate effects, leading to significant fish kills.8 Equally damaging, but less obvious, is the long-term release of contaminants to interstitial waters and the overlying water column. Major factors that can mobilize substances from sediments and into surrounding waters include changes in salinity and oxygen content of the water, acidity, introduction of organic complexing agents, and microbial activity.9 The variability in these factors creates a complex coupling of the aqueous and sedimentary environments, which can produce counter-intuitive and frustrating results for water quality managers. Thus, one cannot assume that high concentrations of a pollutant in sediments are necessarily linked to high pollutant concentrations in the nearby waters. In Boulder Creek, Arizona, for example, concentrations of copper, lead, and cadmium make up almost two percent by weight of the bottom sediments near an old mine, but alkaline stream conditions prevent large quantities of toxins from entering the water and the stream supports a robust aquatic community a short distance below the mine.10 In a more disheartening example, a 1983 algal bloom in the Potomac River was partially linked to improved sewage treatment, with summer nitrification of sewage discharge increasing the water alkalinity and promoting large releases of phosphorous from bottom sediments.11 The biological effects of chemicals in sediments are even more difficult to define than the relation between sediments and water quality. Although damage to aquatic organisms from sediment contamination has been well documented in numerous settings, the ability to predict potential damages is poor.12 Under natural environmental conditions, a host of factors other than the concentration of a given contaminant in sediments can influence the viability of an organism. These factors include the chemical form of the contaminant; synergistic effects when multiple contaminants are present; the nature of the individual organism and specie; community structure; physical disturbances (e.g., boat traffic and associated turbulence); water quality; and related environmental conditions, such as temperature, salinity, and pH. Damages to water quality and aquatic organisms resulting from contaminated sediments have prompted a number of agencies to take regulatory and remedial actions at specific sites.13 Preliminary work by the Environmental[21 ELR 10022] Protection Agency (EPA) and the consulting firm Battelle strongly suggests, however, that sediment pollution is not limited to these sites but is present nationwide in both fresh and marine waters.14 Despite using a data set with geographic gaps, the study discovered that metal concentrations at 293 sites across the United States exceeded tentative sediment standards by a factor of three. Pesticides exceeded sediment standards by a factor of three at 453 sites; and PCBs, polynuclear aromatic hydrocarbons (PAHs), cyanide, and phthalates exceeded these tentative standards by a factor of three at 134 locations. Pesticide hot spots tended to be uniformly distributed across the country, while metal and non-pesticide organic pollutants in sediments were generally clustered near industrial areas of the Northeast, Great Lakes, and West Coast. These results are even more disturbing because the data did not include floodplain or offshore environments, where concentrations may be orders of magnitude higher due to the high clay component of the sediments. Damage to natural resources resulting from contamination of aquatic sediments has been well documented. The ongoing debate within environmental, industrial, and regulatory communities no longer centers on whether sediment contamination should be regulated, but rather on how to best regulate sediment pollution. Identifying Polluted Sediments: The First Step in Regulation The starting point in the debate over regulating sediment contamination has consistently revolved around a simple question: how can one distinguish between a clean and a polluted sediment? The answer will largely define the scope of the contaminant problem, the responsible parties, the remedial cleanup efforts needed, and the costs of cleanup. Given the potential for the answer to force costly investments by the government and private sectors, it is not surprising that the approaches to solving this issue have raised a contentious debate within the scientific and regulatory communities.15 In broad terms, several major issues have dominated the debate over how to define contaminated sediments, including: (1) what medium or media (i.e., sediments, water, or organic matter) should be tested to determine if sediments are polluted; (2) should the tests provide a universal standard applicable at any site or should the tests be based on a set of site-specific parameters; and (3) should the standards be set up for individual chemicals or should testing procedures allow for evaluation of multi-chemical mixtures? The question of which medium or media to use is crucial, since the answer in large part will determine whether the test must be site specific and whether the test must be used for individual chemicals or chemical mixtures. The many media that can be used to define contamination thresholds complicate the debate. Sediment pollution can be defined as a function of the pollutant concentrations in sediments, the pollutant concentrations in interstitial waters, the pollutant concentrations in benthic flora and fauna, how the sediments impact biological populations, or some combination of the above. Concentrations of pollutants in sediments can be used to define contaminant thresholds by setting arbitrary levels that concentrations may not exceed, or by using partition coefficients to define levels where contaminant concentrations in sediments adversely affect water quality. Concentrations in interstitial waters (i.e., the water between sediment particles) can be measured to determine if sediments are polluting surrounding waters. Measuring contaminant concentrations in body tissues of biota provides a direct measure of the transfer of pollutants into the food chain. Finally, differences between populations at different sites can be used to determine sediment impacts. The earliest sediment criteria were based on contaminant concentrations in natural, background, or reference sediments. These reference levels were used as a baseline to establish numerical criteria that were not to be exceeded in sediments. Early efforts in the Great Lakes16 and Puget Sound17 used the reference technique to set limits on contaminant levels in sediments for open-water dredge disposal. Although simple to use, relatively inexpensive to implement, and useful as a stopgap measure, this technique has major scientific and regulatory flaws. Criteria defined using the reference approach are site-specific and subject to dispute, being largely dependent on which sites are chosen to represent the background or reference conditions. [21 ELR 10023] In the case of synthetic substances (e.g., PCBs), it is impossible to define natural concentrations, and criteria must be based on existing concentrations in already polluted areas, without clear evidence of whether the criteria sufficiently protect aquatic populations and water quality.18 The criteria also do not account for chemical mixtures, the chemical form of the contaminant, or other factors that affect bioavailability and sediment impacts. The Equilibrium Partitioning Approach A more sophisticated technique based on measuring the contaminant levels in sediments is the equilibrium partitioning approach.19 This approach assumes that during unchanging (i.e., equilibrium) chemical conditions, the ratio (i.e., the partitioning) of contaminant concentrations in bed sediments and interstitial waters remains constant if one corrects for such factors as organic content. Using this technique, one can estimate sediment impacts on water quality by multiplying the contaminant concentration in sediments by the partitioning coefficient. If the resultant value violates existing water quality standards, the sediment is considered polluted. EPA's Criteria and Standards Division has used this technique to develop interim sediment criteria for nonpolar hydrophobic organic compounds (e.g., DDT, dieldrin, heptachlor, lindane, and PCB)20 and is presently modifying the approach for establishing criteria for heavy metals and polar organics.21 A major advantage of the partitioning approach is that it can theoretically account for site-specific factors, so it can be used by regulators on a nationwide basis. Thus, regulators can avoid the extensive on-site testing that most other techniques require. The partitioning approach also takes advantage of existing water quality criteria that have a well established toxicological basis. As with water quality criteria, the equilibrum partitioning approach cannot, however, take into account the effects of chemical mixtures or the potential effects of chemicals for which no water quality criteria exist. The equilibrium approach is also limited by the two major assumptions on which it is based. First, that the system is in chemical equilibrium. Second, that the biota are primarily affected by sediment contamination of the surrounding water, rather than by direct contact with and ingestion of the sediments, or by food chain enrichment. Variations in the sediment/water ratio, concentrations of dissolved organic matter, and techniques for determining the partitioning coefficient can also generate a wide range of partitioning coefficients for a given substance.22 EPA's Scientific Advisory Board has recommended additional research to validate the technique before it receives widespread application.23 In the past, the effort to develop partitioning-based numerical sediment criteria has been criticized on the grounds that a comprehensive national inventory of contaminated sediments had not been completed and EPA had failed to demonstrate a need for criteria.24 This argument creates a "catch-22": the inventory is necessary to develop the criteria, but no inventory can be completed until criteria exist to define contaminated and clean sediments. EPA has proceeded to assert that numerical criteria must first be developed in order to inventory the extent of the problem. The Interstitial Water Approach An obvious way to avoid the assumption of equilibrium partitioning among sediments, waters, and associated chemistry problems is to sample the interstitialwaters directly to determine if they violate existing water quality criteria. Although appealing at first glance, and offering the same advantages as the equilibrium partitioning technique, this approach has problems that may prove fatal to its future use. Like the equilibrum partitioning approach, the water quality approach does not account for contamination resulting from direct contact with the sediments, food chain enrichment, effects of chemical mixtures, or the impacts of chemicals for which water quality criteria do not exist. It also cannot be applied in intermittently dry and wet areas, such as floodplains, even though these areas are often major sources of contaminated sediments in aquatic systems.25 In addition, and perhaps most damaging, the accurate and consistent measurement of contaminant levels in interstitial waters is difficult.26 The invasive act of sampling often alters pore water concentrations, thus providing an inaccurate portrait of interstitial water concentrations. Extremely small colloidal materials and organic particles in the water samples are also difficult to remove on a consistent basis, which can lead to substantially different analytical results depending on which lab does the testing.27 The Sediment-Biota Technique. Ultimately, the goal of managing sediments is to minimize damage to aquatic organisms and humans. Assessing the health of aquatic organisms provides an obvious avenue for determining if [21 ELR 10024] sediments are contaminated. One variation on this organism-based approach is the sediment-biota equilibrium partitioning technique, which compares chemical levels in sediments and biota to determine how much of the contaminant load becomes part of an organism's body burden. This approach is appealing because it can be used to set sediment criteria using existing Food and Drug Administration (FDA) guidelines for human consumption or water quality criteria combined with chemical modeling. The sediment-biota technique, however, is limited to evaluating single chemicals, substances for which FDA or water quality criteria exist, and non-water-soluble organics. The assumption of equilibrium is also particularly difficult to prove in living organisms. Finally, it is not clear that FDA standards developed to protect human health effectively protect the health of aquatic organisms. The Sediment-Bioassay Approach. Another biological effects-based technique for identifying contaminated sediments is the sediment-bioassay approach. This method is more comprehensive than the biota partitioning approach, because it delineates polluted sediments on the basis of mortality, sublethal effects, and bioconcentration within aquatic organisms. The bioassay technique can be used in the laboratory with spiked sediments to determine dose-response relations for specific chemicals, or with sediments collected in the field to identify the effects of a complex chemical mixture. The sediment-bioassay technique isbased on the same methods used to develop water quality criteria and thus has clear scientific and legal precedents.28 It is also the technique that has been used in the past by EPA and the Army Corps of Engineers (the Corps) to evaluate dredge materials for ocean disposal.29 Widespread application of this approach is limited, however, by methodological considerations. Standard sediment-bioassay methods do not exist and an enormous effort would be required to develop standard methods for a wide variety of organisms with different feeding habits in different habitats. The field bioassay test also does not indicate the relative effects of different chemicals within the sediments mixture, which makes it difficult to determine appropriate mitigation techniques and allocate liability. The Screening-Level Concentration Approach. The screening level concentration (SLC) approach uses contaminant concentrations and data on species' presence at multiple sites to establish criteria intended to provide protection for 95 percent of the sediment-dwelling species.30 The SLC approach can be used at any site for any substance, deals well with chemical mixtures, and is consistent with EPA's water quality goal of protecting 95 percent of aquatic organisms. Regulators, however, have shied away from the SLC approach for a number of reasons.31 The SLC can be very costly to implement, requiring extensive sampling of both sediments and a variety of species at many sites. The site and species selection process can also bias the results and produce very high or low SLCs. Because the SLC approach is based on field sampling, it cannot control for effects of such environmental variables as temperature, salinity, and pH, which can control species presence independent of any contaminant effects. Furthermore, there is a risk that the presence or absence of species at some or all of the sites is controlled by an unmonitored contaminant so that the SLC values established for monitored substances at those sites are meaningless. Like the bioassay approach, the SLC method does not distinguish between the effects of individual chemicals within the sediments, which complicates attempts to set SLCs for specific chemicals. Despite these limitations, the SLC approach provides a mechanism for establishing no-effect levels and has been used to suggest interim criteria for eight organic contaminants.32 Other widely reviewed approaches combine features from the previously discussed methods. The sediment quality triad (SQT) approach33 and the apparent effects threshold (AET) method34 are very similar, requiring documentation of sediment chemistry at a number of field sites, bioassays using field and reference sediments, and a study of indicators of the health of the benthic community at different sites (e.g., community structure or histopathological abnormalities, such as liver lesions in bottom-feeding fish). The AET approach evaluates these factors independently to generate criteria below which effects on biota are essentially nonexistent.35 The SQT technique combines the data [21 ELR 10025] to establish criteria for both minimal and severe biological effects. The AET and SQT approaches provide good means for evaluating the effects of chemical mixtures in sediments and can be used for any contaminant and any species. They also require both laboratory and field analyses of biological response to contamination, thus providing a control and a field situation to evaluate effects of unmonitored environmental variables (e.g., salinity). Interim criteria established primarily by the AET method and partially with sediment equilibrium partitioning are under consideration for adoption in Puget Sound by the State of Washington.36 These approaches, however, suffer from many of the same problems as the SLC and bioassay techniques. They are site-specific, they do not discriminate between effects of individual chemicals, results may be skewed by unmonitored contaminants, and the procedures are costly. EPA's Scientific Advisory Board has recommended the AET approach for use at specific sites, but determined that because the developed criteria do not necessarily represent cause and effect relationships, the AET should "not be used to develop general, broadly applicable sediment quality criteria."37 Present Status of Criteria Development At the moment, the sediment equilibrium partitioning and AET/triad approaches are receiving the most regulatory interest, although research into all the evaluative techniques continues. The partitioning approach provides a universal standard that requires a large initial cost in research, but would be relatively inexpensive to apply once criteria are set. Unfortunately, like the water quality standards it is based on, it is not well suited for assessing the effects of chemical mixtures and may be based on assumptions that are occasionally false. In contrast, AET/triad-type techniques provide good site-specific criteria, but cannot be applied on a general basis, which means that costs of wide-scale implementation could be prohibitive. A major thrust of ongoing research is to develop standardized methods and numerical criteria that can be applied universally. Present approaches have different strengths and most scientists recommend using several of the techniques in a tiered fashion to evaluate sites.38 EPA and the Corps, for example, have adopted a tiered protocol for evaluating whether dredge spoil can be disposed of at open ocean sites.39 The evaluation consists of a series of steps that become progressively more complex and costly, moving from simple physical and chemical analyses of sediments to long-term bioaccumulation studies.40 It is important to note that although EPA and the Corps have agreed on a specific protocol for disposal of dredge sediments in the open ocean, there is still significant debate between and within agencies regarding evaluative protocols for sediments not destined for marine dumping. Even within EPA, each of the methods discussed above is being tested or used by different divisions and regional offices. To date, the relative strengths of the different methods have been largely judged on the basis of economic and biochemical factors. As the various techniques for identifying contaminated sediments move beyond the theoretical phase and are used to regulate sediments and enforce cleanup measures, it is inevitable that the legal basis for regulating sediment contamination will be challenged. The Legal Basis for Regulating Sediments Given the pervasiveness of contaminated sediments and their potential environmental and economic impacts, it is remarkable that the legal and legislative communities have generated so little commentary on the regulation and remediation of contaminated aquatic sediments. With the exception of dredge and fill materials and activities, there is little legal precedent, or research specifically addressing who has the authority to develop sediment criteria and evaluative protocols, what sediments should be covered by these standards, and how sediment quality standards may be enforced to control discharges and force remedial efforts. In the absence of specific laws and regulations regarding contaminated sediments, regulators have largely justified their actions on provisions in existing laws, many of which do not explicitly address the issue of regulating sediments. This section outlines federal legislation frequently cited by regulators as the legal basis for governmental intervention in sediment management.41 Authority to Inventory and Evaluate Sediment Quality The authority to inventory contaminated sediments and the authority to develop procedures or numerical criteria for evaluating sediment quality are closely intertwined. Without the protocols for evaluating sediment quality, no inventory can be completed. Thus, when an agency is authorized to conduct inventories of contamination in water or sediments, it is by implication authorized to develop evaluative procedures. Historically, the authority to inventory sediment pollution and develop evaluation procedures has largely been delegated to the Corps and EPA. However, some state natural resource agencies have taken the lead in recent years. The Corps' authority evolved out of its long history [21 ELR 10026] of maintaining the nation's navigable waters, which often required the dredge and disposal of aquatic sediments as stipulated by the Rivers and Harbors Act of 1899.42 Prior to the late 1960s, issues of sediment quality and the environmental effects from dredge disposal received little, if any, attention. As discussed by Engler,43 and Ablord and O'Neill,44 the increased environmental awareness of the 1960s rapidly changed this perspective. In 1968, the Corps enlarged the scope of its review process to include evaluating the effects of sediment dredging and disposal activities on fish and wildlife, pollution, esthetics, and ecology.45 The National Environmental Policy Act (NEPA)46 of 1969 required the Corps to conduct environmental impact statements when its activities might significantly affect the quality of the human environment. In 1970, amendments to the Rivers and Harbors Act explicitly authorized the Corps to develop techniques for assessing the environmental effects of dredged material disposal. Further, the Marine Protection, Research, and Sanctuaries Act (MPRSA)47 and the Federal Water Pollution Control Act (FWPCA)48 mandated that the Corps consult with EPA in developing approaches to evaluate the effects of discharging dredge materials into ocean and inland waters. Moreover, the MPRSA specifies that criteria for ocean dumping must be updated every three years. Under § 103 of the MPRSA, the Corps is also required to develop regulatory criteria for marine dredge disposal as mandated by the 1975 international Convention on the Prevention of Marine Pollution by Dumping of Wastes and Other Matter (London Dumping Convention).49 The Corps' authority to participate in the development of sediment quality evaluation techniques was further enhanced by § 404 of the FWPCA,50 which authorizes development of methods to prevent adverse impacts from the discharge of dredge materials. Like the Corps, EPA takes its mandate to develop evaluative techniques for dredge sediments from the FWPCA, the MPRSA, and the London Dumping Convention. EPA, however, is interested in protecting all aquatic resources, not just those subject to dredging and dumping. To justify this broader authority, EPA turned to FWPCA § 304, which directs EPA's Administrator to develop "criteria for water quality" for "pollutants in any body of water."51 EPA has interpreted these phrases to include "river bed, lake bed and wetland substrate" based on "the principle that the [FWPCA] should generally be construed broadly to achieve its purposes."52 The authority to inventory contamination or to develop a set of sediment criteria or evaluative methods is also directly mandated or implied by the FWPCA in § 104, which authorizes the EPA Administrator to conduct and promote research on the effects and extent of pollution. In addition, § 115 gives EPA the authority to identify the location of in-place pollutants, and § 118 requires annual reports on the status of Great Lake sediments. Moreover, § 305 mandates biennial state reports on bodies of water in violation of state water quality standards, and § 319 requires reports on environmental problems associated with nonpoint source pollution. Development of testing procedures is also authorized in § 4 of the Toxic Substances Control Act (TSCA).53 A partial summary of legislation that may be used to justify development of sediment evaluation procedures is shown in Table 1. Table 1: Federal Legislation Providing Possible Authority to Manage Contaminated Sediments2
In contrast to the extensive amount of thought and effort put into developing sediment criteria, relatively little research or commentary has examined implementation of these criteria — with the exception of dredge materials. Dredging locations and types of dredge sediments subject to sediment quality evaluation are relatively well defined under existing codes and legislation. Under the FWPCA (Table 1), permits to dredge and dispose of dredge material are subject to sediment quality evaluation. In these cases, the regulatory authority is clearly limited to sediments in dredging or disposal areas. Dredging sites are largely confined to ports, navigation channels, and other congressionally mandated locations. Disposal sites are limited to areas that have undergone environmental evaluation as stipulated by § 404 of the FWPCA and § 103 of the MPRSA. The MPRSA and the London Dumping Convention prohibit dumping of highly radioactive wastes, or chemical or biological warfare agents. Materials that are not chemically contaminated need only be evaluated for compatibility with the disposal site and do not need to undergo complete sediment quality evaluation.54 However, outside of dredging areas, basic issues as to what types of sediments may be regulated, where they may be regulated, and when they may be regulated have not been raised. Defining the boundaries where sediments may be regulated will be a major point of contention in areas such as marshes, wetlands, floodplains, tidal flats, and ephemeral streams that are not permanently inundated, but are occasionally submerged and environmentally linked to adjoining aquatic environments.55 Many of the mining operations in the western United States, for example, have introduced large quantities of heavy metals into such stream beds, which only occasionally contain water. Attempts to apply submerged sediments criteria to these dry land areas will encounter both scientific and legal criticism.56 Alternatively, these areas cannot be ignored, [21 ELR 10028] because they introduce large quantities of contaminants into aquatic systems. Wide-spread attempts to regulate and clean up aquatic sediments will require codification of what constitutes an aquatic sediment for regulatory purposes and what techniques should be used to evaluate sediment quality in different portions of these systems (e.g., in floodplains, marshes, and stream bottoms). On a smaller scale, even if an area has been clearly defined as falling within the regulatory authority of an agency, the issue of where and when sediments at that site are sampled can be a major point of contention. For example, when using equilibrium partitioning or laboratory assays to evaluate sediment quality, the location of sites can substantially alter the test results. Sediment composition, particularly in moderate and high energy environments (e.g., stream bottoms), is notoriously heterogeneous in size. Because contaminants tend to concentrate in fine sediments and composition may vary widely over short distances, samples from adjacent sites may contain widely varying concentrations of contaminants.57 The timing of sample collection can also be critical to test results. In the most extreme example, dry period sampling of dry streams will indicate high sediment contaminant concentrations, because much of the dissolved load is left behind on sediment surfaces as the water is lost to evaporation and percolation. Even in permanently submerged bottom sediments, contaminant concentrations may change during high or low energy conditions as fine particles are scoured or deposited. Given the wide extent of sediment contamination and growing governmental intervention in forcing sediment cleanups, it is only a matter of time before issues of location, timing, and sampling generate legal challenges to sediment quality standards and their application in defining andregulating contaminated sediments. Authority to Enforce Source Control and Remediation With the exception of dredge materials, few laws or regulations exist that explicitly outline governmental authority to enforce sediment cleanup. In a survey of regulators, most stated that their authority to enforce sediment remedial efforts derived from laws aimed at protecting water quality, with over 75 percent of those surveyed citing the MPRSA and the FWPCA.58 The MPRSA, the FWPCA, and other laws provide regulators with two potential mechanisms for managing contaminated sediments: discharge controls, and site cleanup and restoration (Table 1). Source controls are the first step in mitigating sediment contamination, because it makes little sense to restore a site if ongoing pollutant discharges will recontaminate it. A key issue in justifying source controls on water discharges and air emissions will be the linkage of those emissions to downstream contamination of the aquatic sediments. This can be a difficult point to prove, especially in areas where multiple sources exist. If the linkage can be well defined, several pieces of legislation provide potential regulatory tools for controlling discharges. The FWPCA has provisions that might be used to implement controls on discharges with local and watershed scale sediment impacts. Nonpoint controls might be instituted under § 319 of the FWPCA, which requires states to develop nonpoint source management programs, although this section provides weak enforcement options. Sections 303 and 402 provide potentially more powerful weapons for curtailing point source discharges that contaminate sediments. Under these sections, equilibrium partitioning sediment criteria might be used as a basis for setting waste load allocations and granting national pollution discharge elimination system (NPDES) permits, much as present water quality criteria are used to regulate point source discharges.59 However, the granting of discharge permits on the basis of sediment quality criteria will be problematic. The scientific protocol for using sediment quality criteria to set discharge limits on contaminants in water is, at best, unclear. Moreover, discharges in compliance with NPDES permits based on water quality criteria can generate contaminant levels in sediments that violate sediment quality standards. For example, long-term low-level releases to river waters may gradually accumulate to dangerous levels in sediments. NPDES permits based on sediment quality criteria in this case could be very restrictive. Both the Resource Conservation and Recovery Act (RCRA)60 and the Comprehensive Environmental Response, Compensation, and Recovery Act (CERCLA)61 might be used at local sites to reduce or eliminate sediment contaminating discharges. Under RCRA, EPA can force operators of treatment, storage, or disposal facilities for hazardous wastes to restrict or cease operations that are polluting groundwaters or surface waters. CERCLA provides similar provisions at abandoned waste sites, although preventive measures generally are not taken unless contamination is bad enough to place the site on the Superfund National Priorities List. Discharges of substances that contaminate sediments on a regional or national basis could potentially be regulated under TSCA, the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA),62 or under the Clean Air Act.63 Under § 5 of TSCA, discharges can be limited by restricting the use of chemicals or by totally banning their production, as with the production of PCBs. Likewise, pesticides with widespread distribution in sediments might also be regulated under FIFRA, which empowers the federal government to restrict where and when biocides can be used. Provisions of the Clean Air Act might be invoked to curtail emissions linked to widespread contamination of sediments.64 Once contaminated discharges have been curtailed, remedial steps can be taken. Remediation may consist of in-place treatment or removal and disposal at another site. On-site treatment is largely regulated through CERCLA's [21 ELR 10029] remedial investigation/feasibility study (RI/FS) process, which requires evaluation of remedial approaches on environmental and cost/benefit bases. Disposal of contaminated dredge materials from navigation channels and ports is specifically regulated under the MPRSA, the FWPCA, and the London Dumping Convention (Table 1). In addition, §§ 5 and 6 of TSCA provide that materials with certain PCB levels must be incinerated or disposed of in a TSCA/RCRA-approved site or an alternative facility approved by the EPA regional administrator. Furthermore, under RCRA, any hazardous waste must be disposed of in a RCRA-approved site. RCRA's definition of hazardous waste can be very restrictive and can make disposal of dredge material prohibitively costly in many cases. The Corps' position is that dredge materials are not a solid waste, but are natural and therefore exempt from RCRA requirements. It is likely that the potential legislative and administrative conflicts resulting from managing extremely contaminated sediments in navigable channels and ports have not yet been fully played out. As regulators become more aggressive in pushing for sediment cleanups in the coming decade, it is likely that industry will challenge the government's right to regulate sediments. Legal challenges will doubtlessly exploit the fact that existing laws do not specifically address issues of sediment contamination. Courtroom arguments will focus on the inaccurate scientific documentation of sediment contamination due to sampling problems, insufficient proof that contaminant levels in sediments are environmentally harmful, and inadequate linking of industrial discharges to sediment contamination. Scientific arguments will also focus on the costly and uncertain status of efforts to remediate sediment contamination. The development of remediation techniques for contaminated aquatic sediments is recent. The range of cleanup responses to the contamination of aquatic sediments include no action, in-situ containment and/or treatment, and dredging and disposal, sometimes with treatment.65 Sediment treatments alter the contaminant load by reducing the sediment volume or by destroying, extracting, or immobilizing the contaminant.66 There are few widely accepted cleanup techniques, so attempts to remediate sediment pollution can easily bog down in a morass of uncertainty. Major issues confronting sediment cleanups include the following: causing damaging environmental side effects from sediment removal or treatment; allocating remediation costs; choosing among various remedial measures in the absence of clear criteria and experimental evidence; setting appropriate cleanup goals; and finding appropriate remediation methods for extremely large volumes of low-level contaminated sediments (in contrast to the relatively small volumes of extremely contaminated sediments for which techniques have been developed at Superfund sites). The following sections outline the basic nature of the cleanup techniques, the situations in which those techniques are considered most appropriate, and some problems associated with different cleanup measures. The no-action approach is a viable option that should be given serious consideration in the context of contaminated aquatic sediments. It is viable because natural sedimentation may bury and contain the pollutants, and natural degradation and solution processes can sometimes reduce contaminant loads. For example, 13 years of fishing restrictions in Virginia's James River were lifted in 1988 when natural dilution and burial by clean sediments reduced kepone concentrations in surface sediments to tolerable levels.67 The no action option is appealing because of its low cost and because it entails none of the environmental side effects associated with dredging or capping procedures. Measures required to remediate the 500 km2 of kepone in James River sediments, for instance, would have adversely affected large areas of benthic habitat and cost between $ 3 billion and $ 9 billion.68 "No-action," as used in sediment mitigation jargon, may be misleading. Although no direct actions are taken to confine, remove, or treat sediments at the site, substantial activity may be directed at preventing further pollution or mitigating pollutant effects. In particular, it is essential that the polluting discharge be halted in the no-action scenario, because the sediments will continue to be repolluted even as natural processes cleanse them. Moreover, efforts to secure the polluted area to prevent human contact or contamination of wildlife may be necessary until the area is relatively clean. Securing such areas may have far-reaching effects, as with the commercial fishing ban in response to James River kepone contamination. Natural processes of sediment mixing and burial may also be encouraged in order to dilute or to cover the contaminated sediments. Although contrary to most environmental policy, maintaining a constant or accelerated input of clean sediments to contaminated systems can provide a rapid burial system. If the polluted area is small, silt curtains or flocculents can also be used to enhance sedimentation and burial of the contaminated sediments.69 The no-action alternative is appropriate when natural processes will substantially reduce the environmental effects of polluted sediments within a reasonable time. No-action is therefore suitable when the polluting discharge has been halted, when natural burial or dilution processes are rapid, and when the contaminated sediments will not be remobilized by human or natural activities. This final factor can be troublesome, especially when pollutants are located in navigation ways that require periodic dredging that reintroduces buried contaminated sediments to surface waters. The no-action alternative is also appropriate when environmental impacts of sediment cleanup are more damaging than allowing the sediments to remain in place. The process of dredging or treating sediments can lead to [21 ELR 10030] widespread destruction of aquatic wildlife,70 while disposal of the sediments can destroy valuable habitat. Possible in-place controls consist of containment, treatment, or combinations of the two. In practice, in-place treatment of contaminated aquatic sediments has been carried out only at experimental levels or on small scales, and most management agencies do not presently consider it a viable option.71 In-place controls therefore generally focus on containment. Contaminated sediments can be contained by placing a cap over the sediments or by combining capping with lateral confining structures, such as dikes.72 Lateral confinement is necessary in cases where contaminated and cap materials might spill (e.g., on sloping surfaces) or be disturbed (e.g., in shallow waters subject to wave action). Lateral confining structures also help ensure that cap materials are properly placed and effectively cover the contaminated sediments. Capping is generally accomplished by dumping clean sands or silts on top of the contaminated sediments. Silt caps need to be thicker because currents can easily displace the materials, and because silts are bioturbated to a greater depth.73 Long-term monitoring of a number of sites in New England indicates that capping with silts and sands can effectively contain contaminated sediments over a period of 10 years. At smaller sites, flexible hollow containers may be laid over a site and filled with grout to confine the sediments. Active cap materials can also be used that inhibit the contaminant flux from sediments to overlying waters. Lime or calcium carbonate caps, for example, increase the pH of nearby waters and decrease the solubility of metals.74 Addition of calcium carbonate or aluminum sulfate has also been shown to reduce the phosphorous flux to overlying waters and eutrophication.75 It is possible that a cap with activated carbon will reduce contaminant flux to the water column, although experiments on this have been conducted only at the laboratory scale.76 Confinement is appropriate if: the no-action option does not provide sufficient protection; polluting discharges have been halted; the cost and environmental effects of moving or treating the sediments are too great; sources of capping materials are available; hydrologic conditions will not disturb the site; and the area is not subject to dredging. In some cases, capping can be used for habitat enhancement, as at the St. Paul Waterway Superfund site in Washington, where clean sediments will be used to create a large intertidal area with varying substrates for aquatic biota.77 Problems associated with capping generally result from inaccurate emplacement of the cap (particularly in deeper waters) or erosion of the cap. Confinement options must always be accompanied by long-term monitoring plans to ensure that sediments remain in place and that contaminants do not bioaccumulate in local biota. Cost allocation is also problematic. Covering costs of sediment capping is further complicated by the fact that capping probably does not constitute a "preferred treatment" under § 121 of CERCLA, which provides for Superfund contributions to capping programs.78 Experimental in-place treatments have primarily focused on solidifying the sediments or on immobilizing the contaminants. Setting agents, such as cement, can be added to sediments to physically solidify and sometimes chemically immobilize the contaminants. However, difficulties with generating correct mixtures of water, setting agent, and sediment in subaqueous settings limit application of this technique. In-place solidification has been practiced with success in Japan, but this work did not address chemical mobility.79 Bacteria have been tested in attempts to immobilize metals by converting them into insoluble sulfides.80 Problems associated with in-situ treatments are largely a function of their unproven nature. Little is known about costs of large-scale treatments, their effectiveness, or possible toxic by-products from treatment processes. Removal, Disposal, and Treatment Most research and regulatory emphases on remediation of contaminated aquatic sediments have focused on dredging and disposal techniques. In particular, the Corps' Waterways Experiment Station has investigated contaminated dredge removal81 and disposal82 since the early [21 ELR 10031] 1970s. Treatment options for dredge material have been investigated on a more ad hoc basis, generally in association with Superfund sites. The removal of contaminated sediments is appropriate when environmental impacts are severe, environmental conditions such as wave turbulence or flooding and associated scour prohibit leaving the sediments in place, or sediments are located in navigation ways that must be dredged. A variety of dredges may be used to remove contaminated sediments, with the choice of dredge dependent on the nature of the sediment and contaminant, the depth to bottom, the thickness and volume of sediments, the distance to disposal site, and available machinery. Many of the best dredges for removing contaminated sediments have been developed by the Dutch and Japanese, but cannot be used in the United States because of trade restrictions.83 The biggest environmental problem associated with dredging of contaminatedsediments is resuspension of the sediments and the resulting loss of volatiles and solubles to the water column. Resuspension occurs due to dredge action at the sediment-water interface, during transfer of the sediment to a storage vessel, due to slop or leakage from the vessel, and during disposal. Water contamination by volatiles is generally less with mechanical dredges, which cut the sediments with an augur or blade. Hydraulic dredges are less likely, however, to introduce solubles to the water column.84 The price of contaminated dredge removal can pose obstacles, with costs ranging from $ 11.50 to $ 23.00 per cubic yard, as compared with $ 1 to $ 2 per cubic yard for removal of clean sediments.85 Transportation of the dredge materials can be by boat, truck, rail, or pipeline. A major concern in transporting the dredge material is spillage, particularly during loading and unloading operations. In some cases, decontamination of sediment-handling equipment is required. Chemical changes during transport are also a concern. Dewatering, for example, can lead to oxidation of sediments and increased solubility of the contaminants at the disposal site.86 Contaminated sediments may be disposed of in aquatic, nearshore, or upland dumping sites. Relatively clean contaminated sediments can be disposed of at unconfined aquatic sites.87 More polluted sediments require confinement and/or treatment. As with in-place controls,confinement of dredge materials at subaqueous sites consists of capping and lateral enclosure. Problems not encountered with in-place confinement include resuspension of contaminated sediments during emplacement and the difficulty of placing the contaminated materials precisely within the boundaries of the containment facility. There are several advantages to using confined shoreline facilities rather than subaqueous sites for disposal. Transport distances to nearshore disposal sites are often less because contaminated sediments frequently are located in shallow water harbors close to the shore. Water column contamination during emplacement of contaminated sediments is reduced because sediments are not dropped through a substantial depth of water. Accurate emplacement and monitoring are also easier at nearshore sites. Confined disposal facilities (CDFs), which effectively cap and isolate the contaminated materials, can also create valuable wildlife habitat. At other sites, however, the appearance of good wetlands habitat has attracted wildlife that became contaminated by the sediments or microorganisms in the confined shallow waters and mudflats. Securing CDFs from use by humans and wildlife can be a major concern. Construction of numerous CDFs in the Great Lakes in the 1970s demonstrated that nearshore disposal can be environmentally effective and relatively cost efficient. Costs of constructing the sites (not including land acquisition, engineering, transport of sediments, etc.) in the United States have ranged from $ 0.38 to $ 11.47 per cubic yard.88 In some cases, the value of the newly created land has offset these costs. At upland disposal sites, extremely toxic materials can be disposed of in hazardous waste dumps if sediment volumes are small. Upland disposal options for less contaminated sediments or sediments with relatively immobile contaminant loads include upland confined disposal; use for quarry or stripmine reclamation; soil enhancement in agricultural fields; beach nourishment; and creation of recreation sites (e.g., sledding hills). Bioaccumulation and toxicity must be especially attended to when using dredge material for agriculture. Guidelines already exist for permissible metal levels in sludge applications to agricultural crops intended for consumption.89 Alternatively, the dredge material can be used for nonconsumptive crops (e.g., sod farms). Similar problems confront both nearshore and upland disposal.90 Land acquisition can be difficult, particularly in already built-up nearshore areas. Permitting also poses problems, especially in the face of new wetland protection acts that restrict nearshore activities and the growing pervasiveness of the "not-in-my-backyard syndrome." Transportation to upland sites can be very expensive. Environmental problems confronting nearshore and upland disposal sites are the standard ones associated with waste facilities. They include controlling contaminant migration in groundwater and surface runoff, preventing erosion from gullying or wave action, and preventing plant and animal uptake of contaminants. Dredge sediments for landfills may have significant dewatering requirements, since contaminated materials classified as "liquid" by the RCRA paint filter liquid test may not be disposed of in landfills. Several techniques exist for treating dredge materials. These techniques work either by separating the fine sediments carrying contaminants from the dredge material and thus reducing the waste volume, by immobilizing the pollutants, by extracting the contaminants and recycling [21 ELR 10032] them, by destroying the contaminants, or by some combination of the above. Different treatments are appropriate for different contaminants. For example, stream stripping and biodegradation are only appropriate for organics, while magnetic separation and ion exchange techniques are designed for metals. As with in-situ treatments, most treatment techniques for dredge materials are experimental or have only been used at Superfund sites for small volumes of sediment with high contaminant concentrations. It is not yet clear whether these techniques are economically or scientifically feasible for large volumes of dredge material with low contaminant levels. Separation of contaminated fine sediments can be accomplished with settling basins (where the coarse load settles out first and the fine load is decanted), with clarifiers to separate the water and sediments, with belts or screens that sieve the sediments, and with hydrocyclones that centrifuge the sediments.91 Solidification with setting agents, such as cement, fly ash, slag, and lime, has proven feasible in field situations, with costs ranging from $ 45 to $ 75 per cubic yard, not including removal or disposal.92 Longterm testing of field scale solidified materials has not been carried out, however, and it is unclear whether the process adequately contains contaminants over long periods. Moreover, the chemical effects of setting agents require more research. Lime and fly ash mixtures, for example, tend to increase the solubility of arsenic, chromium, lead, and zinc.93 Techniques for extracting or destroying contaminants in sediments have rarely been attempted outside experimental settings, are expensive, and are probably years away from being useful technologies.94 In general, acid leaching, ion exchange, magnetic separation, electrochemical techniques, and biological and ligand leaching are most effective for heavy metals. Biodegradation, solvent extraction, stream stripping, and thermal treatments are more effective for organics.95 Costs of these techniques generally range between $ 150 to $ 750 per cubic yard, which makes them only feasible for relatively small volumes of very contaminated sediments. The push to regulate contamination in aquatic sediments is still in its infancy. Many basic questions have not yet been answered regarding the scope of the contamination problem, how to distinquish a clean from a polluted sediment, what the legal basis is for regulating sediments, and how to clean up contamination within sediments. Thus, regulators face much uncertainty in attempting to manage sediment pollution. Statewide, regional, and national planners should take this uncertainty into account and avoid rigid management structures for contaminated sediments that specify any one approach. In the immediate future, the best regulatory stance will be flexible, allowing for the testing of different evaluative techniques, the examination of various regulatory mechanisms, and the comparison of different cleanup techniques. 1. In perhaps the first work on problems associated with contaminated sediments, K. Carpenter demonstrated in the 1920s that the mobilization of mine tailings and debris during floods was responsible for fish kills in the lead mining district of Wales. See Carpenter, A Study of the Fauna of Rivers Polluted by Lead Mining in the Aberystwyth District of Cardiganshirer, 11 ANNALS OF APPLIED BIOLOGY 1 (1924). 2. A good overview of PCB contamination and cleanup efforts in the Hudson River is provided by Carcich & Tofflemire, Distribution and Concentration of PCB in the Hudson River and Associated Management Problems, 7 ENVTL. INT'L 73 (1982). 3. Summarized in U.S. ARMY CORPS OF ENGINEERS/WASHINGTON STATE DEPARTMENT OF NATURAL RESOURCES, FINAL ENVIRONMENTAL IMPACT STATEMENT — UNCONFINED OPEN-WATER DISPOSAL SITES FOR DREDGED MATERIAL, PHASE 1 (CENTRAL PUGET SOUND, 1988) [hereafter CORPS/WASH. ST. ENVIRONMENTAL IMPACT STATEMENT]. 4. An excellent table summarizing the wide variety and levels of sediment contamination in the Great Lakes region is found in INTERNATIONAL JOINT COMMISSION, PROCEDURES FOR THE ASSESSMENT OF CONTAMINATED SEDIMENT PROBLEMS IN THE GREAT LAKES: A REPORT TO THE GREAT LAKES WATER QUALITY BOARD BY THE SEDIMENT SUBCOMMITTEE AND ITS ASSESSMENT WORK GROUP 14 (Windsor, Ontario, 1988). 5. Although it is a recent scientific field, the research pertaining to contamination of aquatic sediments is voluminous. A good and relatively nontechnical overview of processes controlling sediment pollution and environmental consequences is supplied by R. ALLAN, THE ROLE OF PARTICULATE MATTER INTHE FATE OF CONTAMINANTS IN AQUATIC ECOSYSTEMS (Scientific Series No. 142, Inland Waters Directorate, Canada Centre for Inland Waters, 1986). 6. The process of metal contamination of sediments and the aquatic environment is comprehensively treated in two books that constitute the basic reference texts for researchers examining heavy metal pollution. See U. FORSTNER & G. WITTMANN, METAL POLLUTION IN THE AQUATIC ENVIRONMENT (2d ed. 1983); W. SALOMONS & U. FORSTNER, METALS IN THE HYDROCYCLE (1984). An abbreviated and more accessible summary for the nonscientist is in J. ELDER, METAL BIOGEOCHEMISTRY IN SURFACE-WATER SYSTEMS: A REVIEW OF PRINCIPLES AND CONCEPTS (U.S. Geological Survey Circular 1013, 1988). 7. The biogeochemical processes controlling contaminant transfer to and from sediments are complex, often difficult to study, and frequently differ from site to site. Even basic references tend to be difficult for the nonchemist to read. Appropriate starting points for persons with introductory college-level chemistry include FORSTNER & WITTMANN, supra note 6, at chap. E, and SALOMONS & FORSTNER, supra note 6, at chap. 2 for a discussion of metal-sediment interactions. See also E. THURMAN, ORGANIC GEOCHEMISTRY OF NATURAL WATERS, chap. 11 (1985) (presentation of organic-sediment geochemical processes). 8. Carpenter, supra note 1; see Wiliams, Joyce & Monk, Stream-Velocity Effects of Heavy Metal Concentrations, 65 AM. WATER WORKS CONTROL A. 275 (1973). 9. FORSTNER & WITTMANN, supra note 6, at 247-70; THURMAN, supra note 7; see also A. HOROWITZ, A PRIMER ON TRACE METAL-SEDIMENT CHEMISTRY (U.S. Geological Survey Water-Supply Paper 2277, 1985). 10. Rampe & Runnells, Contamination of Water and Sediment in a Desert Stream by Metals From an Abandoned Gold mine and Mill, Eureka District, Arizona, U.S.A., 4 APPLIED GEOCHEMISTRY 445 (1989). 11. See METROPOLITAN WASHINGTON COUNCIL OF GOVERNMENTS, POTOMAC RIVER WATER QUALITY 1982-1986, TRENDS AND ISSUES IN THE METROPOLITAN WASHINGTON AREA (1989). 12. A good introduction to the breadth of scientific literature available regarding the effects of contaminated sediments on biological systems is provided in chapters 12 through 18 of K. DICKSON, FATE AND EFFECTS OF SEDIMENT-BOUND CHEMICALS IN AQUATIC SYSTEMS (1987) [hereafter DICKSON]; see also LUOMA, BIOAVAILABILITY OF SEDIMENT-BOUND METALS, THE ROLE OF SEDIMENTS IN THE CHEMISTRY OF AQUATIC SYSTEMS—PROCEEDINGS OF THE SEDIMENT CHEMISTRY WORKSHOP, FEBRUARY 8-12, 1982 (U.S. Geological Survey Circular 969, 1988). 13. See, e.g., Carcich & Tofflemire, supra note 2; CORPS/WASH. ST. ENVIRONMENTAL IMPACT STATEMENT, supra note 3; and INTERNATIONAL JOINT COMMISSION, supra note 4, for summaries of efforts in the Hudson River, Puget Sound, and Great Lakes, respectively; see also WATER QUALITY TASK GROUP, DRAFT CHESAPEAKE BAY BASINWIDE TOXICS REDUCTION STRATEGY (U.S. Environmental Protection Agency Chesapeake Bay Program, 1989), for recent proposed efforts in the Chesapeake Bay region. 14. H. BOLTON, R. BRETELER, B. VIGON, J. SCANLON & S. CLARK, NATIONAL PERSPECTIVE ON SEDIMENT QUALITY (U.S. Environmental Protection Agency, Office of Water Regulations and Standards, EPA Contract No. 68-01-6986, 1985). 15. Much of the following discussion is condensed and summarized from more in-depth explanations of the techniques for identifying contaminated sediments and the debate over these methods. See Chapman, Establishing Sediment Criteria for Chemicals—Regulatory Perspective, in DICKISON supra note 12, at 355; Chapman, Current Approaches to Developing Sediment Quality Criteria, 8 ENVTL. TOXICOLOGY & CHEMISTRY 589 (1989) [hereafter Chapman (1989)]; 1 TETRA TECH, INC., DEVELOPMENT OF SEDIMENT QUALITY VALUES FOR PUGET SOUND (1986). Proceedings of an EPA workshop that initiated much of EPA's effort to develop sediment criteria are contained in JRB ASSOCIATES, BACKGROUND AND REVIEW DOCUMENT OF THE DEVELOPMENT OF SEDIMENT CRITERIA (U.S. Environmental Protection Agency Contract Number 68-01-6388, McLean, Virginia, 1984). The earliest work on managing contaminated sediments occurred in the 1970s and was spearheaded by the Corps in response to the disposal of dredge materials. The legislative history, legal requirements, evaluative procedures, and problems with the procedures used by the Corps prior to 1980 are well summarized in 1 CONTAMINANTS AND SEDIMENTS, ch. 27; ENGLER, PREDICTION OF POLLUTION POTENTIAL THROUGH GEOCHEMICAL AND BIOLOGICAL PROCEDURES: DEVELOPMENT OF REGULATION GUIDELINES AND CRITERIA FOR THE DISCHARGE OF DREDGED AND FILL MATERIAL (R. Baker ed.) (1980) 16. The first guidelines for the disposal of sediments are often called the Jensen criteria and were promulgated in 1971 by the Federal Water Quality Administration (predecessor of EPA), in response to contaminant problems in the Great Lakes. See R. BOWDEN, GUIDELINES FOR THE POLLUTIONAL CLASSIFICATION OF GREAT LAKES SEDIMENTS (U.S. Environmental Protection Agency Region V, 1977). Incredibly, many of the early Jensen criteria set contaminant levels that were lower than average global crustal abundance for the substance. Barium concentrations, for example, of 75 mg/kg in sediments were classified as heavily polluted, when the average crustal abundance of barium is 200 mg/kg. See Engler, supra note 15, at 147. 17. See TETRA TECH, INC., supra note 15, at 5. 18. PCBs are the only substance for which a legislative action level is set. Under TSCA, any sediments with PCB concentrations of 50 ug/g (micrograms per gram) or greater are classified as hazardous waste. Similarly, under RCRA, any sediment with contaminant concentrations in excess of 100 times established safe drinking water standards is considered hazardous. None of these criteria has a scientific basis. 19. See Pavlou, The Use of the Equilibrium Partitioning Approach in Determining Safe Levels of Contaminants in Marine Sediments, in DICKSON, supra note 12, at 388; see also JRB ASSOCIATES, supra note 15; Shea, Developing National Sediment Criteria, 388 ENVTL. SCI. & TECH. 22 (1988). 20. U.S. ENVIRONMENTAL PROTECTION AGENCY, INTERIM SEDIMENT CRITERIA VALUES FOR NONPOLAR HYDROPHOBIC ORGANIC CONTAMINANTS (Office of Water Regulations and Standards, Criteria and Standards Division, 1988). 21. EPA's ongoing effort to develop sediment partitioning-based criteria is best summarized in U.S. ENVIRONMENTAL PROTECTION AGENCY, BRIEFING REPORT TO THE EPA SCIENCE ADVISORY BOARD ON THE EQUILIBRIUM PARTITIONING APPROACH TO GENERATING SEDIMENT QUALITY CRITERIA (Office of Water Regulations and Standards, Criteria and Standards, 1989). 22. TETRA TECH, INC., supra note 15, at 17. 23. SEDIMENT CRITERIA SUBCOMMITTEE, EVALUATION OF THE EQUILIBRIUM PARTITIONING (EQP) APPROACH FOR ASSESSING SEDIMENT QUALITY (U.S. Environmental Protection Agency, Scientific Advisory Board, SAB-EPEC-90-006, 1990). 24. See Lyman, Establishing Sediment Criteria for Chemicals—Industrial Perspective, in DICKSON, supra note 12, at 378. 25. See, e.g., Marcus, Regulating Contaminated Sediments in Aquatic Environments: A Hydrologic Perspective, 13 ENVTL. MGMT. 703 (1989). 26. See, e.g., Fanning & Pilson, Interstitial Silica and pH in Marine Sediments: Some Effects of Sampling Procedures, 173 SCI. 1228 (1971). 27. TETRA TECH, INC., supra note 15, at 11. 28. Chapman (1989), supra note 15. 29. U.S. ENVIRONMENTAL PROTECTION AGENCY/U.S. ARMY CORPS OF ENGINEERS, ECOLOGICAL EVALUATION OF PROPOSED DISCHARGE OF DREDGED MATERIAL INTO OCEAN WATERS: IMPLEMENTATION MANUAL FOR SECTION 103 OF PUBLIC LAW 92-532 (Environmental Laboratory, U.S. Army Engineer Waterways Experiment Station, Vicksburg, Mississippi, 1977). 30. The SLC is determined from the sampling of contaminant concentrations in sediments and numerous benthic species at multiple locations. A species screening level concentration (SSLC) is defined for each species as being the pollutant concentration above which 90 percent of that species is found. For example, if a species is present at one site with a pollutant concentration of 110 parts per million and at nine other sites with higher concentrations, 90 percent of the specie's occurrences are found at concentrations higher than 110 ppm and 110 ppm is the SSLC. The SLC is defined as the contaminant concentration above which 95 percent of the SSLCs are found. For example, if the SSLC for one specie at a site is 20 ppm and the SSLCs for 19 other species range between 40 ppm and higher, the SLC is 40 ppm, because 19 of the 20 SSLCs (i.e., 95 percent of the SLCCs) occur at concentrations higher than 40 ppm. Setting the sediment standard in this manner creates a criteria that protects 95 percent of the species. See TETRA TECH, INC., supra note 15, at 22; see also Neff et al., An Evaluation of Screening Level Concentration Approach to Derivation of Sediment Quality Criteria for Freshwater and Saltwater Ecosystems, in 10 AQUATIC TOXICOLOGY AND HAZARD ASSESSMENT 115 (American Society for Testing and Materials STP 971) (W. Adams, G. Chapman & W. Landis eds., 1987). 31. See Chapman (1989), supra note 15; TETRA TECH, INC., supra note 15, at 25. 32. SLCs for PCBs, DDT, pyrene, benzo(a)pyrene, naphthalene, fluoranthene, chrysene, and benzo(a)anthracene are discussed in Neff et al., supra note 30. 33. Chapman, Sediment Quality Criteria From the Sediment Quality Triad: An Example, 5 ENVTL. TOXICOLOGY & CHEMISTRY 957 (1986); see also Chapman & Long, A Sediment Quality Triad: Measures of Sediment Contamination, Toxicity and Infaunal Community Composition in Puget Sound, 16 MARINE POLLUTION BULL. 405 (1985). 34. The AET approach has been widely reported in the literature. The best summary of its development and use may be found in PTI ENVIRONMENTAL SERVICES, BRIEFING REPORT TO THE EPA SCIENTIFIC ADVISORY BOARD: THE APPARENT EFFECTS THRESHOLD APPROACH (Bellevue, Washington, 1988). 35. To be precise, the AET specifies the criteria to be equal to the contaminant concentration above which adverse effects on biota are noted. An adverse effect is a statistically significant difference (P2 0.05) between conditions in a study area relative to conditions in an appropriate reference area. See S. BECKER, R. PASTOROK, R. BARRICK, P. BOOTH & L. JACOBS, CONTAMINATED SEDIMENTS CRITERIA REPORT 10 (PTI Environmental Services, Bellevue, Washington, 1989). 36. WASHINGTON DEPARTMENT OF ECOLOGY, INTERIM SEDIMENT QUALITY EVALUATION PROCESS FOR PUGET SOUND (1989). 37. SEDIMENT CRITERIA SUBCOMMITTEE, EVALUATION OF THE APPARENT EFFECTS THRESHOLD (AET) APPROACH FOR ASSESSING SEDIMENT QUALITY 1 (U.S. Environmental Protection Agency, Scientific Advisory Board, SAB-EETFC-89-027, 1989). 38. See, e.g., Chapman (1989), supra note 15. 39. See 40 C.F.R. § 220 et seq. (ocean dumping guidlines under the Ocean Dumping Act); 40 C.F.R. § 230 et seq. (disposal guidelines under the FWCPA). 40. See U.S. ENVIRONMENTAL PROTECTION AGENCY, ECOLOGICAL EVALUATION OF PROPOSED DISCHARGES OF DREDGED MATERIAL IN OCEAN WATERS (Draft Report) (Office of Marine and Estuarine Protection, 1989). The Corps' protocol regarding disposal of dredge material is summarized in N. FRANCIGUES, M. PALERMO, C. LEE & R. PEDDICORD, MANAGEMENT STRATEGY FOR DISPOSAL OF DREDGED MATERIAL: CONTAMINANT TESTING AND CONTROLS (Miscellaneous Paper D-85-1, U.S. Army Engineer Waterways Experiment Station, Vicksburg, Mississippi, 1985) [hereafter FRANCINGUES]. 41. A survey of regulators' views on which legislation gives them the authority to regulate sediments is contained in COWAN & ZARBA, FINAL REPORT ON REGULATORY APPLICATIONS OF SEDIMENT QUALITY CRITERIA (Battelle, U.S.E.P.A. Contract No. 68016986, 1987). 42. 33 U.S.C. § 401 et seq. 43. Engler, supra note 15, at 144. 44. Ablord & O'Neill, Wetland Protection and Section 404 of the Federal Water Pollution Control Act Amendments of 1972: A Corps of Engineers Renaissance, 1 VT. L. REV. 51 (1976). 45. 33 C.F.R. § 209.120(d) (1968). 46. 42 U.S.C. §§ 4321-4370a, ELR STAT. NEPA 001-012. 47. 33 U.S.C. §§ 1401-1445. 48. 33 U.S.C. §§ 1251-1387, ELR STAT. FWPCA 001-065. 49. Convention on the Prevention of Marine Pollution by Dumping of Wastes and Other Matter, Dec. 29, 1972, 26 U.S.T. 2403, T.I.A.S. No. 8165, 1046 U.N.T.S. 120; see also EDGAR & ENGLER, AN UPDATE ON THE LONDON DUMPING CONVENTION AND ITS APPLICATION TO DREDGED MATERIALS (Proceedings Dredging 19 Conference, American Society of Civil Engineers 14, 1984). 50. 33 U.S.C. §§ 1251-1387, ELR STAT. FWPCA §§ 001-065. 51. See C. Winer, Memorandum to David K. Sabock, Chief, Criteria and Standards Section, U.S. Environmental Protection Agency, Subject: Development of Sediment Criteria (Oct. 25, 1984) (available from Criteria and Standards Division, U.S. EPA). 52. Id. at 2. 53. 15 U.S.C. § 2603, ELR STAT. TSCA 004. a Modified from Cowan and Zarba, supra note 42, at 15. b Including authorization for demonstration and experimental remedial effort. 54. EDGAR & ENGLER, supra note 49. 55. Marcus, supra note 25. 56. To date, I am aware of only one case, the Sullivan's Ledge Superfund site in New Bedford, Massachusetts, where methods developed for aquatic sediments were applied to intermittent stream and marsh soils. Use of equilibrium partitioning criteria to define contaminated soils at the site was strongly challenged at the Scientific Advisory Board meeting evaluating the EP approach. 57. See Marcus, supra note 25, at 709. 58. COWAN & ZARBA, supra note 41, at 10. 59. Gilford & Zeller, Information Needs Related to Toxic Chemicals Bound to Sediments — A Regulatory Perspective in DICKSON, supra note 12, at 35. 60. 42 U.S.C. §§ 6901-6992k, ELR STAT. RCRA 001-050. 61. 42 U.S.C. §§ 9601-9675, ELR STAT. CERCLA 001-075. 62. 7 U.S.C. § 136-136y, ELR STAT. 001-034. 63. 42 U.S.C. §§ 7401-7642, ELR STAT. 001-052. 64. Gilford & Zeller, supra note 59. 65. Literature on sediment remediation is often hard to access, being buried in in-house company and governmental documents or in RI/FS reports and environmental impact statements. Probably the best overview and introduction to sediment cleanup techniques is found in NATIONAL RESEARCH COUNCIL, CONTAMINATED MARINE SEDIMENTS — ASSESSMENT AND REMEDIATION (1989) [hereafter NRC]. 66. A good summary of existing and experimental treatment alternatives is in INTERNATIONAL JOINT COMMISSION, OPTIONS FOR REMEDIATION OF CONTAMINATED SEDIMENTS IN THE GREAT LAKES (Great Lakes Regional Office, Windsor, Ontario, 1988) [hereafter IJC]. 67. See Huggett, Kepone and the James River, in NRC, supra note 65, at 417. 68. Id. 69. NRC, supra note 65, at 46. 70. Dredging and treatment of PCB-contaminated sediments in the Hudson River, for example, decimated benthic flora and fauna, which only reached their predredge contaminated sediment population levels three years after dredging. If the primary goal had been to protect benthic wildlife, such actions would have had questionable merit. See Carcich & Tofflemire, supra note 2. 71. See, e.g., Orchard, Remedial Technologies Used at International Joint Commission Areas of Concern, in NRC, supra note 65, at 280. 72. Good diagrams of standard capping and confinement configurations and associated containment problems are contained in Cullinane, Averett, Shafer, Truitt, Bradbury & Male, Alternatives for Control/Treatment of Contaminated Dredged Material, in NRC, supra note 65, at 234. 73. Morton, Monitoring the Effectiveness of Capping for Isolating Contaminated Sediments, in NRC, supra note 65, at 262. 74. IJC, supra note 66, at 36. 75. See Kennedy & Cooke, Control of Lake Phosphorous With Aluminum Sulfate: Dose Determination and Application Techniques, 18 WATER RESOURCES BULL. 389 (1982); T. MURPHY, K. HALL, K. ASHLEY, A. MUDROCH, M. MAWHINNEY & H. FRICKER, IN-LAKE PRECIPITATION OF PHOSPHOROUS BY LIME TREATMENT 85 (National Water Research Institute, Environment Canada, Burlington, Canada, 1985). 76. MACKENTHUN, BROSSMAN, KOHLER & TERRELL, APPROACHES FOR MITIGATING KEPONE CONTAMINATION IN THE HOPWELL/JAMES RIVER AREA OF VIRGINIA, PROCEEDINGS OF THE FOURTH U.S./JAPAN MEETING ON MANAGEMENT OF BOTTOM SEDIMENTS CONTAINING TOXIC SUBSTANCES (Water Resources Support Center, U.S. Army Corps of Engineers, 1979). 77. See Ficklin, Weitkamp & Weiner, St. Paul Waterway Remedial Action and Habitat Restoration Project, in NRC, supra note 65, at 440. 78. NRC, supra note 65, at 16. 79. OTSUKI & SHIMA, SOIL IMPROVEMENT BY DEEP CEMENT CONTINUOUS MIXING METHOD AND ITS EFFECT ON THE ENVIRONMENT, PROCEEDINGS OF THE SIXTH U.S./JAPAN EXPERTS MEETING ON MANAGEMENT OF BOTTOM SEDIMENTS CONTAINING TOXIC SUBSTANCES (Water Resources Support Center, U.S. Army Corps of Engineers, 1982). 80. ACRES CONSULTING SERVICES LIMITED, EVALUATION OF PROCEDURES FOR REMOVING AND DECONTAMINATING BOTTOM SEDIMENTS IN THE LOWER GREAT LAKES, (Niagara Falls, Ontario, 46, 1972). 81. See D. HAYES, GUIDE TO SELECTING A DREDGE FOR MINIMIZING RESUSPENSION OF SEDIMENT, ENVIRONMENTAL EFFECTS OF DREDGING PROGRAM (Technical Note EEDP-09-1) (U.S. Army Corps of Engineers Waterways Experiment Station, Vicksburg, Mississippi, 1986). 82. Summarized in FRANCIGUES, supra note 40. 83. For the types of dredges for removing contaminated sediments and their relative merits and weaknesses, see Herbich, Developments in Equipment Designed for Handling Contaminated Sediments, in NRC, supra note 65, at 239, and Cullinane et al., supra note 72. Herbich provides sketches of dredges for the novice and had a useful table outlining performance specifications for the different types of dredges. 84. Cullinane et al., supra note 72. 85. IJC, supra note 66, at 18. Table 4 of this document also provides a useful overview of the range of costs associated with different dredging, confinement, disposal, and treatment techniques for contaminated sediments. 86. FRANCIGUES, supra note 40, at 19. 87. Cullinane et al., supra note 72. 88. IJC, supra note 66, at 19. 89. Id. at 23. 90. See FRANCIGUES, supra note 40, at 21-27. 91. See U.S. ENVIRONMENTAL PROTECTION AGENCY, REMOVAL AND MITIGATION OF CONTAMINATED SEDIMENTS (Hazardous Waste Engineering Research Laboratory, 1985). 92. IJC, supra note 66, at 43. 93. Id. at 41. 94. Cullinane et al., supra note 72. 95. IJC, supra note 66, at 37, 55-65. 21 ELR 10020 | Environmental Law Reporter | copyright © 1991 | All rights reserved |