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Hybrid approaches may combine these three. A fourth approach, in-situ treatment, is currently under development and may become a viable alternative in the future, especially in combination with in-situ caps. Highlight 1-5 in Chapter 1 briefly summarizes these major approaches for sediment sites.
Project managers should consider the following steps, which build on EPA’s RI/FS Guidance by
adding details specific to sediment, when developing alternatives at sediment sites:
1. Develop remedial action objectives specifying the contaminants and media of interest, exposure pathways, and remediation goals that permit a range of alternatives to be
2. Identify estimated volumes or areas of sediment to which the approaches may be applied, taking into account the need for protectiveness as identified in the RAOs and the biological, chemical and physical characteristics of the site;
3. Develop additional detail concerning the equipment, methods, and locations to be evaluated for each alternative, including the three major approaches (e.g., potential natural recovery processes, potential cap materials and placement methods, number and types of dredges or excavators, transport methods, treatment methods, type of disposal units, general disposal location, need for monitoring and/or institutional controls);
4. Develop additional detail concerning known major constraints on each alternative, including the three major approaches at the site (e.g., need to maintain flow capacity for flood control, need to accommodate navigational dredging);
5. To the extent possible with information available at this stage of the FS, identify the time frame(s) in which the alternatives are expected to achieve cleanup levels and RAOs; and
This process often is best done in an iterative fashion, especially at complex sites. For example, investigation into equipment and disposal options for sediment removal may lead to evaluation of a variety of time frames for achieving risk reduction goals. Typically, the number and type of remedial alternatives that a project manager develops for any site is a site-specific decision. The project manager should take into account the size, characteristics, and complexity of the site. However, due to the limited number of approaches that may be available for contaminated sediment, generally project managers should evaluate each approach carefully, including the three major approaches (MNR, in-situ capping, and removal through dredging or excavation) at every sediment site at which they might be appropriate.
3.1.1 Alternatives that Combine Approaches
At sites with multiple water bodies or sections of water bodies with differing characteristics or uses, or differing levels of contamination, project managers have found that alternatives that combine a variety of approaches are frequently the most promising. In many cases, institutional controls are also part of many alternatives (see Section 3.6, Institutional Controls). The following examples illustrate how
different approaches might be combined into alternatives:
C An alternative might combine armored in-situ capping of contaminated sediment in more erodible areas, with MNR in highly depositional areas;
3-2 Chapter 3: Feasibility Study Considerations C An alternative might combine dredging in federal navigation channels or for areas where there is insufficient water depth to maintain navigation or flood capacity with a cap, with in-situ capping of floodplain, intertidal or under-pier areas where a more technically practicable and less costly approach is desired; and
3.1.2 No-Action Alternative The NCP at Title 40 Code of Federal Regulations (40 CFR) §300.430(e)(6) provides that the noaction alternative should be considered at every site. The no action alternative should reflect the site conditions described in the baseline risk assessment and remedial investigation. This alternative may be a no-further-action alternative if some removal or remedial action has already occurred at the site, such as under another ROD.
No-action or no-further-action alternatives normally do not include any treatment, engineering controls, or institutional controls but may include monitoring. For example, at a site where risk is acceptable (e.g., because contaminant levels in surface sediment and biota are low and the site is stable), but the site contains higher levels of contamination at depth, it may be advisable to evaluate periodically the continued stability of buried contaminants. A no action alternative may include monitoring of these buried contaminants. Project managers and others should not confuse this however with MNR, where natural processes are relied upon to reduce an unacceptable risk to acceptable levels. The difference is often the increased level and frequency of monitoring included in the MNR alternative and the fact that the MNR alternative includes a cleanup level and expected time frame for achieving that level. Project managers should normally evaluate both a no action alternative and a MNR alternative at sediment sites.
If a no-action or no-further-action alternative does not meet the NCP’s threshold criteria addressed in 40 CFR §300.430 (i.e., protection of human health and the environment and meeting applicable or relevant and appropriate requirements), it is not necessary to carry it though to the detailed analysis of alternatives. However, the ROD should explain why the no action alternative was dropped from the analysis. Chapter 7, Remedy Selection Considerations, includes guidance on when it may be appropriate to select a no-action alternative.
3.1.3 In-Situ Treatment and Other Innovative Alternatives
Generally, in-situ treatment is an approach that involves the biological, chemical, or physical treatment of contaminated sediment in place. This approach is currently under development by researchers and several pilot- and full-scale applications of the more promising technologies are underway. Although significant technical limitations currently exist for many of the treatment technologies, the results of the ongoing testing may demonstrate the viability of some of these approaches in certain situations. Project managers are encouraged to track the development of in-situ treatment
methods. Potential in-situ treatment methods include the following:
• Biological Treatment: Enhancement of microbial degradation of contaminants by the addition of materials such as oxygen, nitrate, sufate, hydrogen, nutrients, substrate (e.g., organic carbon), or microorganisms into the sediment or into a reactive cap;
• Chemical Treatment: The destruction of contaminants through oxidation and dechlorination processes by providing chemical reagents, such as permanganate, hydrogen peroxide, or potassium hydroxide, into the sediment or into a reactive cap; and
Most techniques for in-situ treatment of sediment are in the early stages of development, and few methods are currently commercially available. Experiences gained to date in experimental or small-scale applications of in-situ remedies have indicated that technical limitations to the effectiveness of available in-situ treatments continue to exist. For example, in-situ remedies relying on the addition of required substrates and nutrients, reagents, or catalysts have been developed for some contaminants, such as polychlorinated biphenyls (PCBs), but developing an effective in-situ delivery system to add and mix the needed levels of reagents to contaminated sediment is more problematic. The lack of an effective delivery system has also hindered the application of in-situ stabilization systems [National Research Council (NRC) 2001]. However, new developments may make this a more promising approach in the future.
Several EPA-funded bench and field studies in this area are underway. These include studies conducted by EPA’s Superfund Innovative Technology Evaluation (SITE) program, which encouraged the development and routine use of innovative treatment, monitoring, and measurement technologies.
The SITE program is in the process of completing demonstration of several in-situ treatment technologies (Highlight 3-1). More information on the SITE program is available at http://www.epa.gov/ORD/SITE/.
Also, the Hazardous Substance Research Center (HSRC) - South and Southwest, is performing research about in-situ treatment and other innovative capping alternatives for contaminated sediment in the Anacostia River in Washington, DC. More information on this program is available from the HSRC Web site at http://www.hsrc.org.
3-4 Chapter 3: Feasibility Study Considerations Other sources of information about innovative approaches to contaminated sediment management include the U.S. Army Corps of Engineers’ (USACE) Dredging Operations Environmental Research Program (DOER), which has contributed substantially to work in the area of risk assessment methods, fate and transport models, and dredging and capping technologies. Information on this program and on the Dredging Operations Technical Support (DOTS) program is available at http://el.erdc.usace.army.
mil/dots. In addition, the Strategic Environmental Research and Development Program (SERDP) has made recent investments in contaminated sediment research. Information about these projects can be accessed from the SERDP Web site at http://www.serdp.org.
3.2 NCP REMEDY SELECTION CRITERIA
The NCP at 40 CFR §300.430(e)(9) establishes a framework of nine criteria for evaluating remedies. These criteria address the requirements of the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA), and additional technical and policy considerations that are important for selecting remedial actions. Many of these criteria are also important for actions under the Resource Conservation and Recovery Act (RCRA).
The NCP at 40 CFR §300.430(e)(7) describes a method for screening potential alternatives prior to developing detailed alternatives when a number of alternatives are being considered at a site. Only the alternatives judged as the best or most promising following this screening should be retained for further development and detailed analysis. The three broad criteria for screening preliminary remedial alternatives are: 1) effectiveness; 2) implementability; and 3) cost. Although a screening level analysis may be necessary in some cases, due to the relatively limited number of approaches available for sediment, project managers generally should not screen out any of the three major approaches early in the FS.
More detailed discussions of what should be addressed under each of the nine criteria can be found in the ROD Guidance (U.S. EPA 1999a) and the RI/FS Guidance (U.S. EPA 1988a). The following provides a summary of the nine criteria (U.S. EPA 1988a). More detailed explanations related to sediment sites are cited after each criterion, as appropriate.
• Compliance with Applicable or Relevant and Appropriate Requirements (ARARs): This criterion is used to evaluate whether the alternative complies with chemical-specific, action-specific, and location-specific ARARs or if a waiver is justified. In addition to ARARs, this criterion also commonly includes whether the alternative considers other criteria, advisories, and guidance that are to be considered at the site. This criterion is discussed further with respect to contaminated sediment in Section 3.3.
Balancing Criteria • Long-Term Effectiveness and Permanence: This criterion includes an evaluation of the magnitude of human health and ecological risk from untreated contaminated materials or treatment residuals remaining after remedial action has been concluded (known as residual risk), and the adequacy and reliability of controls to manage that residual risk. It also includes an assessment of the potential need to replace technical components of the alternative, such as a cap or a treatment system, and the potential risk posed by that replacement. This criterion is discussed further with respect to contaminated sediment in Section 3.4;
• Reduction of Toxicity, Mobility, and Volume Through Treatment: This criterion refers to the evaluation of whether treatment processes can be used, the amount of hazardous material treated, including the principal threat that can be addressed, the degree of expected reductions, the degree to which the treatment is irreversible, and the type and quantity of treatment residuals. This criterion is discussed further with respect to contaminated sediment in Chapters 4, 5, and 6 related to the individual remedies;
• Short-Term Effectiveness: This criterion includes an evaluation of the effects of the alternative during the construction and implementation phase until remedial objectives are met. This criterion includes an evaluation of protection of the community and workers during the remedial action, the environmental impacts of implementing the remedial action, and the expected length of time until remedial objectives are achieved.
This criterion is discussed further with respect to contaminated sediment in Section 3.4;
• Implementability: This criterion is used to evaluate the technical feasibility of the alternative, including construction and operation, reliability, monitoring, and the ease of undertaking an additional remedial action if the remedy fails. It also considers the administrative feasibility of activities needed to coordinate with other offices and agencies, such as for obtaining permits for off-site actions, rights of way, and institutional controls, and the availability of services and materials necessary to the alternative, such as treatment, storage, and disposal facilities. This criterion is discussed further with respect to contaminated sediment in Chapters 4, 5, and 6 related to the individual remedies; and • Cost: This criterion includes an evaluation of direct and indirect capital costs, including costs of treatment and disposal, annual costs of operation, maintenance, monitoring of the alternative, and the total present worth of these costs. This criterion is discussed further with respect to contaminated sediment in Section 3.5.
• State (Or Support Agency) Acceptance: This criterion is used to evaluate the technical and administrative concerns of the state (or the support agency, in the case of state-lead sites) regarding the alternatives, including an assessment of the state or the support agency’s position and key concerns regarding the alternative, and comments on ARARs or the proposed use of waivers. Tribal acceptance is also evaluated under this criterion.
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• Community Acceptance: This criterion includes an evaluation of the concerns of the public regarding the alternatives. It determines which component of the alternatives interested persons in the community support, have reservations about, or oppose. This criterion is discussed further with respect to contaminated sediment in Chapter 1, Section 1.6.
Additional guidance about how to apply these criteria to sediment alternatives is found throughout the guidance, as indicated above. In addition, Chapter 7, Remedy Selection Considerations, summarizes general considerations of each of the nine criteria with respect to the three major approaches.
3.3 APPLICABLE OR RELEVANT AND APPROPRIATE REQUIREMENTS
Pursuant to CERCLA §121(d)(4), all remedial actions at CERCLA sites must be protective of human health and the environment. In addition, on-site actions need to comply with the substantive portions of ARARs unless the ARAR is waived. ARARs may be waived only under limited circumstances. Compliance with administrative procedures, such as permits, is not required for on-site response actions. Off-site actions must comply with both substantive and administrative requirements of legally applicable laws and regulations.