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Sediment cleanup levels for response actions under CERCLA are generally based on site-specific risk assessments, but are occasionally based on ARARs. Project managers may also consider nonpromulgated advisories or guidance issued by federal, state, or tribal governments, frequently called TBC (“to be considered”). While TBCs may not be legally binding on their own, and, therefore, do not have the same status as ARARs, TBCs can be used as a basis for making cleanup decisions. The project manager should refer to CERCLA Compliance with Other Laws Manual (U.S. EPA 1988b). Also, the preamble to the final NCP (55 Federal Register (FR) 8741) states that, as a matter of policy, it is appropriate to treat Indian tribes as states for the purpose of identifying ARARs (see NCP at 40 CFR §300.515(b) for provisions dealing with tribal governments).
The process of identifying ARARs typically begins in the scoping phase of the RI/FS, continues until the ROD is finalized, and may be reexamined during the five-year review process. Identification of ARARs should be done on a site-specific basis and usually involves a two-part analysis. First, a determination of whether a given requirement is applicable should be made, and second, if it is not applicable, then a determination should be made as to whether it is relevant and appropriate. Highlight 3-2 lists some examples of potential federal, state, and tribal ARARs for sediment sites and actual and hypothetical examples of how remedial strategies have been adapted to comply with ARARs.
For more information about ARARs, the project manager should consult the Compendium of CERCLA ARARs Fact Sheets and Directives (U.S. EPA 1991b), and the Assessment and Remediation of Contaminated Sediments (ARCS) Program Remediation Guidance Document (U.S. EPA 1994d).
As part of the ARARs analysis, project managers, in consultation with the site attorney, should consider appropriate requirements promulgated under the Clean Water Act (CWA). As described in the examples in Highlight 3-2, federal water quality criteria as well as state-promulgated regulations 3-7 Chapter 3: Feasibility Study Considerations including state water quality standards may be potential ARARs for surface water when water is discharged from dewatering or treatment areas or as effluent from confined disposal facilities (CDFs).
Furthermore, some states may have their own promulgated sediment quality standards that may be potential ARARs for sediment.
Total maximum daily loads (TMDLs) established or approved by the EPA under the CWA are planning tools designed to reduce contributing point and nonpoint sources of pollutants in water quality limited segments (WQLS). TMDLs calculate the greatest amount of loading of a pollutant that a water body can receive without exceeding CWA water quality standards. TMDLs are usually established by the states, territories, or authorized tribes and approved by the EPA. Effluent limits in point source national pollutant discharge elimination system (NPDES) permits should be consistent with the assumptions and requirements in a wasteload allocation in an approved TMDL.
EPA-established TMDLs are not promulgated as rules, are not enforceable, and, therefore, are not ARARs. TMDLs established by states, territories or authorized Indian tribes may or may not be promulgated as rules. Therefore, TMDLs established by states, territories, or authorized Indian tribes, should be evaluated on a regulation-specific and site-specific basis. Even if a TMDL is not an ARAR, it may aid in setting protective cleanup levels and may be appropriately a TBC. Project managers should work closely with regional EPA Water program and state personnel to coordinate matters relating to TMDLs. The project manager should remember that even when a TMDL or wasteload allocation is not enforceable, the water quality standards on which they are based may be ARARs. TMDLs can also be useful in helping project managers evaluate the impacts of continuing sources, contaminant transport, and fate and effects. Similarly, Superfund’s RI/FS may provide useful information and analysis to the federal and state water programs charged with developing TMDLs.
Project managers are also strongly encouraged to follow the consultation requirements of the Endangered Species Act. For on-site actions, the Endangered Species Act, Section 7, requires federal agencies to ensure that the actions they authorize, fund or carry out are not likely to jeopardize the continued existence of endangered or threatened species, or adversely modify or destroy their critical habitat. By policy, EPA consults with the U.S. Fish and Wildlife Service and the National Marine Fisheries Service (NMFS) where a threatened or endangered species or their habitat is or may be present.
The Commencement Bay NPL (National Priorities List) site provides an example of how a remedial strategy has been adapted to comply with this act. Chinook salmon are threatened species that are found at this site during part of the year. After following EPA’s policy of consulting with the NMFS, EPA decided that to avoid harming the species, some in-water remedial work would be conducted only during a window of time when juvenile salmon were not migrating through the area. Other in-water work would be performed outside of this window, using special conditions recommended by NMFS to minimize impacts to salmon.
Project managers are also strongly encouraged to follow the consultation requirements of the National Historic Preservation Act, Section 106 (36 CFR part 800). Section 106 requires federal agencies to consider the effects of their actions on historic properties that are on or are eligible for listing on the National Register of Historic Places. Compliance generally includes conducting a preliminary survey to determine the presence of significant resources, including among others, historic, prehistoric, archeological, architectural, engineering or cultural resources. If significant resources are found, generally a documentation package is prepared for review and comment by the State or Tribal Historic Preservation Office and appropriate mitigation is included in site plans. Examples of how remedial strategies have been adapted to comply with this Act include the Pine Street Canal Site in Vermont, where mitigation for damages related to capping sunken barges and other historic features included study and artifact collection by a local maritime museum related to a historic sunken barge of similar type in nearby Lake Champlain. In addition, at the Fox River PCB (polychlorinated biphenyl) site in Wisconsin, historic and prehistoric artifacts will be protected during nearby site activities and a potential shipwreck site will either be avoided during dredging or a diver study employed for further examination.
Project managers should also be aware of Executive Orders such as those covered by the Statement of Procedures on Floodplain Management and Wetland Protections (Appendix A of 40 CFR part 6). Although not ARARs, the Agency normally follows Executive Orders as a matter of policy. The Statement of Procedures cited above sets forth EPA policy and guidance for carrying out Executive Orders 11988 and 11990, which were written in furtherance of the National Environmental Policy Act (NEPA) and other environmental statutes. Executive Order 11988 concerns floodplain management and the evaluation by federal agencies of the potential effects of actions they may take in a floodplain to avoid, to the extent possible, adverse effects associated with direct and indirect development of a floodplain. Executive Order 11990 concerns protection of wetlands and the avoidance by federal agencies, to the extent possible, of the adverse impacts associated with the destruction or loss of wetlands if a practical alternative exists. OSWER Directive 9280.0-03, Considering Wetlands at CERCLA Sites (U.S. EPA 1994e), contains further guidance on addressing this Executive Order.
Examples of ways in which remedial strategies for sediment have been adapted in light of these
Executive Orders as a matter of policy include the following:
• EPA determined that capping above grade would be an inappropriate alternative for remediating contaminated sediment in a small river, as the increased bottom elevation would increase the risk of flooding. Instead, the final EPA remedy called for dredging contaminated sediment and capping back to the existing grade; and • EPA selected a route that avoided the wetland and would minimize the potential for effects on the floodplain, after evaluating possible alignments for the access road to the contaminated sediment site. During design of the access road, additional features were incorporated to further minimize any indirect impact on the floodplain.
3.4 EFFECTIVENESS AND PERMANENCE OF SEDIMENT ALTERNATIVES
Two NCP balancing criteria for which project managers of sediment sites may find additional guidance helpful are those related to short-term effectiveness, and long-term effectiveness and permanence. Each is described in more detail below, as it relates to evaluation of contaminated sediment
alternatives. The NCP describes the assessment of short-term effectiveness as follows 40 CFR
The short-term impacts of alternatives shall be assessed considering the following:
(1) Short-term risks that might be posed to the community during implementation of an alternative;
(2) Potential impacts on workers during remedial action and the effectiveness and reliability of protective measures;
(3) Potential environmental impacts of the remedial action and the effectiveness and reliability of mitigative measures during implementation; and (4) Time until protection is achieved.
For contaminated sediment alternatives, short-term risks to the community and workers may include those that may occur during dredging or capping operations or during the first few years of a MNR remedy. For a sediment remedy involving bioaccumulative contaminants, short-term impacts may include those due to continued human or ecological exposure to contaminants currently in the food chain.
For a MNR alternative, these impacts may also be frequently due to continued human and ecological exposure to contaminants in surface sediment. For in-situ capping, short-term impacts may be due to factors such as contaminant releases during capping or accidents during transport or placement of cap material. For dredging or excavation, short-term impacts may include those due to contaminant releases during sediment removal, transport, treatment, or disposal or accidents during construction and operation of facilities. Short-term impacts to the benthic community as a result of capping or dredging should also be considered. Additional possible short-term impacts are presented in Highlight 7-3, Examples of Some Key Differences Between Remedial Approaches for Contaminated Sediment.
The time needed until protection is achieved can be difficult to assess at sediment sites, especially where bioaccumulative contaminants are present. Generally, for sites where risk is due to contaminants in the food chain, time to achieve protection can be estimated using models. These models may have significant uncertainty, but may be useful for predicting whether or not there are significant differences between time to achieve protection using different alternatives. When comparing time to achieve protection from MNR to that for active remedies such as capping and dredging, it is generally important to include the time for design and implementation of the active remedies in the analysis.
The NCP describes the assessment of long-term effectiveness and permanence as follows (40 CFR §300.430(e)(9)(iii)(C)):
Alternatives shall be assessed for the long-term effectiveness and permanence they afford, along with the degree of certainty that the alternative will prove successful. Factors that shall be
considered, as appropriate, include the following:
(1) Magnitude of residual risk remaining from untreated waste or treatment residuals remaining at the conclusion of the remedial activities. The characteristics of the residuals should be 3-14 Chapter 3: Feasibility Study Considerations considered to the degree that they remain hazardous, taking into account their volume, toxicity, mobility, and propensity to bioaccumulate; and (2) Adequacy and reliability of controls such as containment systems and institutional controls that are necessary to manage treatment residuals and untreated waste. This factor addresses in particular the uncertainties associated with land disposal for providing long-term protection from residuals; the assessment of the potential need to repair or replace technical components of the alternative, such as a cap, a slurry wall, or a treatment system; and the potential exposure pathways and risks posed should the remedial action need replacement.
For contaminated sediment alternatives, residual risk generally may be considered to be the risk remaining after completion of dredging, capping, or MNR. In their evaluation of residual risk, project managers should consider the volume, toxicity, mobility, and bioavailability of the remaining contaminants, as well as their propensity to bioaccumulate. The adequacy and reliability of controls used to manage post-remediation sediment residuals or untreated contamination that remains in the sediment should also be considered. Where institutional controls such as fish consumption advisories are one of the controls used to manage residual risk, project managers should assess their expected effectiveness and whether resulting exposures are expected to be within protective levels. Developing answers to the following questions may help the project manager in evaluating the long-term effectiveness and
permanence of alternatives:
• What is the level of human health and/or ecological risk remaining after implementation?
• What is the expected pattern of risk reduction over time for the various alternatives and what uncertainties are associated with that pattern?
It is important to remember that each of the three major approaches may be capable of reaching acceptable levels of both short-term effectiveness and long-term effectiveness and permanence, and that site-specific characteristics should be reviewed during the alternatives evaluation to ensure that the 3-15 Chapter 3: Feasibility Study Considerations selected alternative will be effective in that environment. Project managers should evaluate and compare the effectiveness of in-situ (capping and MNR) and ex-situ (dredging) alternatives under the conditions present at the site. There should not be necessarily a presumption that removal of contaminated sediments from a water body will be necessarily more effective or permanent than capping or MNR.
Likewise, without sufficient evaluation there should not be a presumption that capping or MNR will be effective or permanent. What constitutes an acceptable level of effectiveness and permanence is a sitespecific decision that should also consider each of the other NCP remedy selection criteria. Each of the major approaches for sediment has its own remedy-specific considerations under these criteria, which are summarized below. Some aspects are discussed in more detail in the following remedy-specific chapters.
Monitored Natural Recovery
For a MNR remedy, the risk present at the time of remedy selection should decrease with time as natural processes progress. The level of risk reduction afforded by this remedy generally depends on what cleanup levels the natural processes are expected to be able to achieve in a reasonable time frame and the level of contamination which may continue to enter the system from any uncontrolled sources.