Prepared for submission to Contaminated Soil, Sediment & Water Magazine

March 13, 2002

Richard J. Wenning 1

¹ Environ International Corporation, Marketplace Tower, 6001 Shellmound Street, Suite 700, Emeryville, California USA 94608 TEL 510-420-2556 / FAX 510-655-9517 / E-MAIL rjwenning@environcorp.com

* Richard J. Wenning is a senior manager in the environmental sciences practice and the firm’s national contaminated sediment practice at ENVIRON International Corporation in San Francisco, California.

Earlier Sediments Forum columns described how several academic institutions, industry, and the United States Environmental Protection Agency (USEPA) have initiated projects and research programs to develop testing methods, assessment tools, management technologies and decision-making matrices for addressing contaminated sediments. From these efforts, the concept of risk assessment and risk-based decision-making has often emerged as a potentially unifying principle for managing contaminated sediments.

Two significant developments over the past year exemplify the federal government’s renewed focus on risk-based decision-making. First was the National Research Council’s (NRC) January 2001 publication, Risk Management Strategy for PCB-Contaminated Sediments¹. The NRC report summarized the current state of knowledge on human health and ecological impacts posed by PCB contaminated sediments, and provided recommendations for a wide-range of investigation and research activities as part of a strategy to reduce risks. The NRC report described the framework developed by the Presidential/Congressional Commission on Risk Assessment and Risk Management² as the appropriate foundation for developing a management framework. It encouraged the use of risk assessment methods to manage the risks posed by PCB-contaminated sediments, evaluate potential remediation options, and evaluate post-remediation conditions.

The second important development was USEPA’s Office of Emergency and Remedial Response (OERR) May 2001 technical forum on managing contaminated sediments³. The forum brought together several state regulatory agencies, industry, environmentalists, and Native American tribes to exchange views on the important science and policy issues involved in making site-specific remediation and risk management decisions.

USEPA’s Eleven Guiding Principles

The Office of Solid Waste and Emergency Response (OSWER) is the latest to weigh-in on sediments with the release on February 12 of this year of eleven guiding principles for managing contaminated sediment risks at hazardous waste sites⁴. OSWER directive 9285.6-08 issued by USEPA Assistant Administrator Marianne Lamont Horinko to Superfund National Policy Managers and RCRA Senior Policy Advisors is intended to guide USEPA site managers toward development of scientifically sound and nationally consistent risk management decisions at contaminated sediment sites. The directive lists eleven risk management principles that Remedial Project Managers (RPMs), On-Scene Coordinators (OSCs), and RCRA Corrective Action project managers should consider when planning and conducting sediment investigations and selecting and implementing a response.

The OSWER guidance recommends that USEPA site managers make risk-based site decisions using an iterative decision process that evaluates the short-term and long-term risks of all potential cleanup alternatives. Decisions must continue to be consistent with the National Oil and Hazardous Substances Pollution Contingency Plan’s (NCP’s) nine remedy selection criteria (40 CFR Part 300.430). But in addition, USEPA site managers are now explicitly encouraged to consider the societal and cultural impacts of sediment contamination and potential remedies through involvement of affected stakeholders. Implementation of decisions at particular sites also should be tailored to the size and complexity of the site, to the magnitude of site risks, and to the type of action contemplated.

With permission from USEPA, the eleven guiding principles are reprinted below.

Principle 1: Control Sources Early

As early in the process as possible, site managers should try to identify all direct and indirect continuing sources of significant contamination to the sediments under investigation. These sources might include discharges from industries or sewage treatment plants, spills, precipitation runoff, erosion of contaminated soil from stream banks or adjacent land, contaminated groundwater and non-aqueous phase liquid contributions, discharges from storm water and combined sewer outfalls, upstream contributions, and air deposition.

Next, site managers should assess which continuing sources can be controlled and by what mechanisms. It may be helpful to prioritize sources according to their relative contributions to site risks. In the identification and assessment process, site managers should solicit assistance from those with relevant information, including regional Water, Air, and PCB Programs (where applicable); state agencies (especially those responsible for setting Total Maximum Daily Loads (TMDLs) and those that issue National Pollutant Discharge Elimination System (NPDES) permits); and all Natural Resource Trustees. Local agencies and stakeholders may also be of assistance in assessing which sources can be controlled.

Site managers should evaluate the potential for future recontamination of sediments when selecting a response action. If a site includes a source that could result in significant recontamination, source control measures will likely be necessary as part of that response action. However, where USEPA believes that the source can be controlled, or where sediment remediation will have benefits to human health and/or the environment after considering the risks caused by the ongoing source, it may be appropriate for the Agency to select a response action for the sediments prior to completing all source control actions. This is consistent with principle #5 below, which indicates that it may be necessary to take phased or interim actions (e.g., removal of a hot spot that is highly susceptible to downstream movement or dispersion of contaminants) to prevent or address environmental impacts or to control human exposures, even if source control actions have not been undertaken or completed.

Principle 2: Involve the Community Early and Often

Contaminated sediment sites often involve difficult technical and social issues. As such, it is especially important that a project manager ensure early and meaningful community involvement by providing community members with the technical information needed for their informed participation.

Meaningful community involvement is a critical component of the site characterization, risk assessment, remedy evaluation, remedy selection, and remedy implementation processes. Community involvement enables USEPA to obtain site information that may be important in identifying potential human and ecological exposures, as well as in understanding the societal and cultural impacts of the contamination and of the potential response options.

The NRC report (p. 249) “recommends that increased efforts be made to provide the affected parties with the same information that is to be used by the decision-makers and to include, to the extent possible, all affected parties in the entire decision-making process at a contaminated site. In addition, such information should be made available in such a manner that allows adequate time for evaluation and comment on the information by all parties.”

Through Technical Assistance Grants and other mechanisms, project managers can provide the community with the tools and information necessary for meaningful participation, ensuring their early and continued involvement in the cleanup process.

Although the Agency has the responsibility to make the final cleanup decision at CERCLA and RCRA sites, early and frequent community involvement facilitates acceptance of Agency decisions, even at sites where there may be disagreement among members of the community on the most appropriate remedy.

Site managers and community involvement coordinators should take into consideration six practices, which were recently presented in OSWER Directive 9230.0-99 Early and Meaningful Community Involvement ⁵. These are (1) energize the community involvement plan; (2) provide early, proactive community support; (3) get the community more involved in the risk assessment; (4) seek early community input on the scope of the remedial investigation/feasibility study (RI/FS); (5) encourage community involvement in identification of future land use; and, (6) do more to involve communities during removals.

Principle 3: Coordinate with States, Local Governments, Tribes, and Natural Resource Trustees

Site managers should communicate and coordinate early with states, local governments, tribes, and all Natural Resource Trustees. By doing so, they will help ensure that the most relevant information is considered in designing site studies, and that state, local, tribal, and trustee viewpoints are considered in the remedy selection process. For sites that include water bodies where TMDLs are being or have been developed, it is especially important to coordinate site investigations and monitoring or modeling studies with the state and with USEPA’s water program. In addition, sharing information early with all interested parties often leads to quicker and more efficient protection of human health and the environment through a coordinated cleanup approach.

Superfund’s statutory mandate is to ensure that response actions will be protective of human health and the environment. USEPA recognizes, however, that in addition to USEPA’s response action(s), restoration activities by the Natural Resource Trustees may be needed. It is important that Superfund site managers and the Trustees coordinate both the USEPA investigations of risk and the Trustee investigations of resource injuries in order to most efficiently use federal and state resources and to avoid duplicative efforts.

Additional information on coordinating with Trustees may be found in OSWER Directive 9200.4-22A⁶ CERCLA Coordination with Natural Resource Trustees, in the 1992 ECO Update The Role of Natural Resource Trustees in the Superfund Process⁷, and in 1999 OSWER Directive 9285.7-28 P ⁸ Ecological Risk Assessment and Risk Management Principles for Superfund Sites. Additional information on coordinating with states and tribes can be found in OSWER Directive 9375.3-03P⁹ The Plan to Enhance the Role of States and Tribes in the Superfund Program.

Principle 4: Develop and Refine a Conceptual Site Model that Considers Sediment Stability

A conceptual site model should identify all known and suspected sources of contamination, the types of contaminants and affected media, existing and potential exposure pathways, and the known or potential human and ecological receptors that may be threatened. This information is frequently summarized in pictorial or graphical form, backed up by site-specific data.

The conceptual site model should be prepared early and used to guide site investigations and decision-making. However, it should be updated periodically whenever new information becomes available, and USEPA’s understanding of the site problems increases. In addition, it frequently can serve as the centerpiece for communication among all stakeholders.

A conceptual site model is especially important at sediment sites because the interrelationship of soil, surface and groundwater, sediment, and ecological and human receptors is often complex. In addition, sediments may be subject to erosion or transport by natural or man-made disturbances such as floods or engineering changes in a waterway. Because sediments may experience temporal, physical, and chemical changes, it is especially important to understand what contaminants are currently available to humans and wildlife, and whether this is likely to change in the future under various scenarios.

The risk assessor and project manager, as well as other members of the site team, should communicate early and often to ensure that they share a common understanding of the site and the basis for the present and future risks. The May 1998 USEPA Guidelines for Ecological Risk Assessment¹⁰, the 1997 Superfund Guidance Ecological Risk Assessment Guidance for Superfund: Process for Designing and Conducting Ecological Risk Assessments¹¹, and the 1989 Risk Assessment Guidance for Superfund (RAGS), Volume 1, Part A¹² provide guidance on developing conceptual site models.

Principle 5: Use an Iterative Approach in a Risk-Based Framework

The NRC report (p. 52) recommends the use of a risk-based framework based on the one developed by the Presidential/Congressional Commission on Risk Assessment and Risk Management². However, as recognized by the NRC (p. 60): “The framework is intended to supplement, not supplant, the CERCLA remedial process mandated by law for Superfund sites.”

Although there is no universally accepted, well-defined risk-based framework or strategy for remedy evaluation at sediment sites, there is widespread agreement that risk assessment should play a critical role in evaluating options for sediment remediation. The Superfund program uses a flexible, risk-based framework as part of the CERCLA and NCP process to adequately characterize ecological and human health site risks. The guidance used by the RCRA Corrective Action program13 also recommend a flexible risk-based approach to selecting response actions appropriate for the site.

USEPA encourages the use of an iterative approach, especially at complex contaminated sediment sites. As used here, an iterative approach is defined broadly to include approaches which incorporate testing of hypotheses and conclusions and foster re-evaluation of site assumptions as new information is gathered. For example, an iterative approach might include pilot testing to determine the effectiveness of various remedial technologies at a site. As noted in the NRC report (p. 66): "Each iteration might provide additional certainty and information to support further risk-management decisions, or it might require a course correction."

An iterative approach may also incorporate the use of phased, early, or interim actions. At complex sediment sites, site managers should consider the benefits of phasing the remediation. At some sites, an early action may be needed to quickly reduce risks or to control the ongoing spread of contamination. In some cases, it may be appropriate to take an interim action to control a source, or remove or cap a hot spot, followed by a period of monitoring in order to evaluate the effectiveness of these interim actions before addressing less contaminated areas.

The NRC report makes an important point when it notes (p. 256): “The committee cautions that the use of the framework or other risk-management approach should not be used to delay a decision at a site if sufficient information is available to make an informed decision. Particularly in situations in which there are immediate risks to human health or the ecosystem, waiting until more information is gathered might result in more harm than making a preliminary decision in the absence of a complete set of information. The committee emphasizes that a ‘wait-and-see’ or ‘do-nothing’ approach might result in additional or different risks at a site.”

Principle 6: Carefully Evaluate the Assumptions and Uncertainties Associated with Site Characterization Data and Site Models

The uncertainties and limitations of site characterization data, and qualitative or quantitative models (e.g., hydrodynamic, sediment stability, contaminant fate and transport, or food-chain models) used to extrapolate site data to future conditions should be carefully evaluated and described. Due to the complex nature of many large sediment sites, a quantitative model is often used to help estimate and understand the current and future risks at the site and to predict the efficacy of various remedial alternatives.

The amount of site-specific data required and the complexity of models used to support site decisions should depend on the complexity of the site and the significance of the decision (e.g., level of risk, response cost, community interest). All new models and the calibration of models at large or complex sites should be peer-reviewed consistent with the Agency’s peer review process as described in its Peer Review Handbook¹⁴.

Site managers should clearly describe the basis for all models used and their uncertainties when using the predicted results to make a site decision. As recognized by the NRC report (p. 65), however, “Management decisions must be made, even when information is imperfect. There are uncertainties associated with every decision that need to be weighed, evaluated, and communicated to affected parties. Imperfect knowledge must not become an excuse for not making a decision.”

Principle 7: Select Site-specific, Project-specific, and Sediment-specific Risk Management Approaches that will Achieve Risk-based Goals

USEPA’s policy has been and continues to be that there is no presumptive remedy for any contaminated sediment site, regardless of the contaminant or level of risk. This is consistent with the NRC report’s statement (p. 243) that “There is no presumption of a preferred or default risk-management option that is applicable to all PCB-contaminated-sediment sites.”

At Superfund sites, for example, the most appropriate remedy should be chosen after considering site-specific data and the NCP’s nine remedy selection criteria. All remedies that may potentially meet the removal or remedial action objectives (e.g., dredging or excavation, in-situ capping, in-situ treatment, monitored natural recovery) should be evaluated prior to selecting the remedy. This evaluation should be conducted on a comparable basis, considering all components of the remedies, the temporal and spatial aspects of the sites, and the overall risk reduction potentially achieved under each option.

At many sites, a combination of options will be the most effective way to manage the risk. For example, at some sites, the most appropriate remedy may be to dredge high concentrations of persistent and bioaccumulative contaminants such as PCBs or DDT, to cap areas where dredging is not practicable or cost-effective, and then to allow natural recovery processes to achieve further recovery in net depositional areas that are less contaminated.

Principle 8: Ensure that Sediment Cleanup Levels are Clearly Tied to Risk Management Goals

Sediment cleanup levels have often been used as surrogates for actual remediation goals (e.g., fish tissue concentrations or other measurable indicators of exposure relating to levels of acceptable risk). While it is generally more practical to use measures such as contaminant concentrations in sediment to identify areas to be remediated, other measures should be used to ensure that human health and/or ecological risk reduction goals are being met. Such measures may include direct measurements of indigenous fish tissue concentrations, estimates of wildlife reproduction, benthic macroinvertebrate indices, or other “effects endpoints” as identified in the baseline risk assessment.

As noted in the NRC report (p. 123), “The use of measured concentrations of PCBs in fish is suggested as the most relevant means of measuring exposures of receptors to PCBs in contaminated sediments.” For other contaminants, other measures may be more appropriate. For many sites, achieving remediation goals, especially for bioaccumulative contaminants in biota, may take many years. Site monitoring data and new scientific information should be considered in future reviews of the site (e.g., the Superfund five-year review) to ensure that the remedy remains protective of human health and the environment.

Principle 9: Maximize the Effectiveness of Institutional Controls and Recognize their Limitations

Institutional controls, such as fish consumption advisories and waterway use restrictions, are often used as a component of remedial decisions at sediment sites to limit human exposures and to prevent further spreading of contamination until remedial action objectives are met. While these controls can be an important component of a sediment remedy, site managers should recognize that they might not be very effective in eliminating or significantly reducing all exposures. If fish consumption advisories are relied upon to limit human exposures, it is very important to have public education programs in place.

For other types of institutional controls, other types of compliance assistance programs may also be needed (e.g., state/local government coordination). Site managers should also recognize that institutional controls seldom limit ecological exposures. If monitoring data or other site information indicates that institutional controls are not effective, additional actions may be necessary.

Principle 10: Design Remedies to Minimize Short-term Risks while Achieving Long-term Protection

The NRC report notes (p. 53) that: “Any decision regarding the specific choice of a risk management strategy for a contaminated sediment site must be based on careful consideration of the advantages and disadvantages of available options and a balancing of the various risks, costs, and benefits associated with each option.”

Sediment cleanups should be designed to minimize short-term impacts to the extent practicable, even though some increases in short-term risk may be necessary in order to achieve a long-lasting solution that is protective. For example, the long-term benefits of removing or capping sediments containing persistent and bioaccumulative contaminants often outweigh the additional short-term impacts on the already-affected biota.

In addition to considering the impacts of each alternative on human health and ecological risks, the short-term and long-term impacts of each alternative on societal and cultural practices should be identified and considered, as appropriate. For example, these impacts might include effects on recreational uses of the water body, road traffic, noise and air pollution, commercial fishing, or disruption of way of life for tribes. At some sites, a comparative analysis of impacts such as these may be useful in order to fully assess and balance the tradeoffs associated with each alternative.

Principle 11: Monitor During and After Sediment Remediation to Assess and Document Remedy Effectiveness

A physical, chemical, and/or biological monitoring program should be established for sediment sites in order to determine if short-term and long-term health and ecological risks are being adequately mitigated at the site and to evaluate how well all remedial action objectives are being met. Monitoring should normally be conducted during remedy implementation and as long as necessary thereafter to ensure that all sediment risks have been adequately managed. Baseline data needed for interpretation of the monitoring data should be collected during the remedial investigation.

Depending on the risk management approach selected, monitoring should be conducted during implementation in order to determine whether the action meets design requirements and sediment cleanup levels, and to assess the nature and extent of any short-term impacts of remedy implementation. This information can also be used to modify construction activities to assure that remediation is proceeding in a safe and effective manner.

Long-term monitoring of indicators such as contaminant concentration reductions in fish tissue should be designed to determine the success of a remedy in meeting broader remedial action objectives. Monitoring is generally needed to verify the continued long-term effectiveness of any remedy in protecting human health and the environment and, at some sites, to verify the continuing performance and structural integrity of barriers to contaminant transport.

Two-Tiered Consultation for CERCLA Sites

To help ensure that USEPA site managers consider these principles before site-specific decisions are made at CERCLA sites, OSWER has established a two-tiered consultation process. The consultation process applies to all proposed or listed NPL sites where USEPA will sign or concur on the ROD, all non-time-critical removal actions where USEPA will sign or concur on the Action Memorandum, and all “NPL-equivalent” sites where there is or will be an USEPA-enforceable agreement in place.

Tier 1 consultation applies to sediment action(s) involving more than 10,000 cubic yards or five acres of contaminated sediment. Consultation entails the submission of the draft proposed action plan, a written discussion of how the above eleven principles were considered, and basic site information that will assist OERR in tracking significant sediment sites.

Tier 2 consultation applies to the largest and most complex, or controversial, contaminated sediment sites. Tier 2 includes a new technical advisory group (Contaminated Sediments Technical Advisory Group–CSTAG) to monitor progress at these sites and provide advice. The group will be comprised of ten regional USEPA staff and approximately five staff from OSWER, OW, and ORD. For most sites, the group will meet with the site manager and the site team several times throughout the site investigation, response selection, and action implementation processes.

For new NPL sites, OSWER indicates that the CSTAG group will meet within one year after the proposed listing. It is anticipated that for most sites, the CSTAG group will meet annually until the ROD is signed and thereafter as needed until all remedial action objectives have been met. The specific areas of assistance or specific documents to be reviewed will be decided by the CSTAG group on a case-by-case basis in consultation with the site team.

RCRA Corrective Action Facilities

OSWER proposes a similar two-tiered consultation process at USEPA-lead RCRA Corrective Action facilities where a sediment response action is anticipated or planned. The Tier 1 consultation process applies to sites where sediment action(s) for the entire site will address more than 10,000 cubic yards or five acres of contaminated sediment. The Tier 2 consultation process is nearly the same as that proposed for the CERCLA program.

Implications for Contaminated Sediment Sites

OSWER is encouraging both CERCLA and RCRA project managers within the Agency to immediately begin to apply these principles at all sites where the risks from contaminated sediment are under investigation. The exceptions to implementation are time-critical actions, emergency removal actions, and sites with only sediment-like materials in wastewater lagoons, tanks, storage or containment facilities, or drainage ditches. The Agency does not wish to delay action in these cases.

OSWER’s directive continues Agency-wide efforts for development of a coordinated national regulatory approach to investigation, remediation, and management of contaminated sediments at hazardous waste sites, active industrial facilities, ports and harbors, and in other impacted waterways. The USEPA is formalizing a process it believes will help promote nationally consistent approaches to evaluate, select and implement protective, scientifically sound, and cost-effective remedies. The Agency is encouraging both state and USEPA project managers working on sediment contamination to consult with their colleagues in other regulatory programs to promote consistent and effective cleanup actions.

Will implementation of the eleven guiding principles and a two-tiered consultation process help at large-scale, complex sediment investigations and cleanups? Only time will tell. For additional information on this guidance, contact the OERR Sediments Team Leader (Stephen Ells at 703-603-8822) or the OSW Corrective Action Programs Branch Chief (Tricia Buzzell at 703-308-8632).

References

1. National Research Council (NRC), A Risk Management Strategy for PCB-Contaminated Sediments, National Academy Press, Washington, D.C. January, 2001. www.nap.edu/openbook/0309073219/html/4.html
2. Presidential/Congressional Commission on Risk Assessment and Risk Management, Framework for Environmental Health Risk Management: Final Report. Washington, D.C. January, 1997. http://www.riskworld.com/Nreports/1996/risk_rpt/Rr6me001.htm.
3. Wenning, R.J. 2001. USEPA’s Forum on Managing Contaminated Sediments at Hazardous Waste Sites: Summary of Policy Discussions. Contam. Soil Sed. Water June/July: 49-54. http://www.epa.gov/OST/cs/congress.html
4. USEPA, Office of Solid Waste and Emergency Response (OSWER). Principles for Managing Contaminated Sediment Risks at Hazardous Waste Sites. Directive 9285.6-08. February, 2002. http://www.epa.gov/superfund/resources/principles/9285.6-08.pdf
5. USEPA, Office of Solid Waste and Emergency Response (OSWER). Early and Meaningful Community Involvement. Directive 9230.0-99. October, 2001. http://www.epa.gov/superfund/pubs.htm.
6. USEPA, Office of Solid Waste and Emergency Response (OSWER). CERCLA Coordination with Natural Resource Trustees. Directive 9200.4-22A. July 1997.
7. USEPA, ECO Update- The Role of Natural Resource Trustees in the Superfund Process. 1999. http://www.epa.gov/superfund/programs/risk/tooleco.htm
8. USEPA, Office of Solid Waste and Emergency Response (OSWER). Ecological Risk Assessment and Risk Management Principles for Superfund Sites. Directive 9285.7-28 P. 1999. http://www.epa.gov/superfund/programs/risk/tooleco.htm
9. USEPA, Office of Solid Waste and Emergency Response (OSWER). The Plan to Enhance the Role of States and Tribes in the Superfund Program. Directive 9375.3-03P. 1999.
   http://www.epa.gov/superfund/states/strole/index.htm
10. USEPA. Guidelines for Ecological Risk Assessment. Federal Register 63(93): 26846 26924. May, 1998. http://www.epa.gov/superfund/programs/risk/tooleco.htm
11. USEPA. Ecological Risk Assessment Guidance for Superfund: Process for Designing and Conducting Ecological Risk Assessments. EPA 540-R-97-006. 1997. http://www.epa.gov/superfund/programs/risk/tooleco.htm
12. USEPA. Risk Assessment Guidance for Superfund (RAGS), Volume 1, Part A. EPA 540-1-89-002. 1989. http://www.epa.gov/superfund/programs/risk/ragsa
13. USEPA, RCRA Corrective Action program http://www.USEPA.gov/correctiveaction/resource/guidance
14. USEPA, Peer Review Handbook. EPA100-B-00-001. 2000. http://www.USEPA.gov/ORD/spc/2peerrev.htm

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