Significance and Use
4.1 This guide provides a consistent and transparent decision-making process for selecting risk-based corrective actions at sediment sites (that is, a Sediment-RBCA). Sediment-RBCA shares the same process as other RBCAs described in E1739, E2081, and E2205/E2205M but with explicit consideration of the constraints on how the available sediment assessment techniques impact decision making. Several factors exist that distinguish sediment sites from upland sites and warrant unique consideration, including background, potential for recontamination, sediment stability, sediment processes, lack of control on exposure and transport, exposure pathways and receptors, and unique site characteristics such as public lands, lack of site control on use and access. The diversity of available assessment techniques for a sediment site is considerably larger than for other media. Guidance on the technical tools themselves are described in other ASTM guides and regulatory guidance manuals.
4.2 Sediment-RBCA incorporates the same paradigm of planning and scoping, problem formulation, exposure and effects assessments, risk characterization, and uncertainty analysis that is common to ecological and human health risk assessment guidance documents. Irrespective of terminology, both Sediment-RBCA and risk assessment share the same science-based process and share the same goal of informing risk management decisions. The specific approach used to develop risk-based human health and ecological criteria and risk-based management plans may vary from site to site based on jurisdictional requirements, site complexity, TPDs, and best professional judgment regarding the appropriate use of different assessment techniques. Some attributes of Sediment-RBCA are:
4.2.1 Description of a tiered approach, including process flow charts, to identify critical steps and provide an overview of the entire RBCA process;
4.2.2 Identification, development, and use of TPDs throughout the Sediment-RBCA process;
4.2.3 Indications of the value and timing of stakeholder involvement, recognizing that some jurisdictions require varying degrees of coordination with a variety of stakeholders;
4.2.4 Identification of situations under which a risk assessment may or may not be necessary;
4.2.5 Identification of decision points where risk assessment results are used as part of the risk management decision making; and
4.2.6 Identification and development of appropriate RAOs to support risk management.
4.3 Activities described in this guide should be conducted by qualified professionals familiar with site characterization, remedial action science and technology, human health and ecological risk assessment methodologies, or related scientific and engineering subject areas, as they relate to complex sediment sites. A defensible application of a RBCA process is often a collaboration of multiple subject matter experts.
4.4 To properly apply the Sediment-RBCA process, the user should AVOID the following:
4.4.1 Using Tier 1 RBSLs as a default remedial action standard without considering if proceeding to develop more refined RBSLs through a Tier 2 or Tier 3 evaluation is appropriate;
4.4.2 Placing arbitrary time constraints on the corrective action process that do not reflect the actual urgency and risk posed by the site;
4.4.3 Failing to document the purpose of the Sediment-RBCA process (that is, defining the management goal per the problem formulation requirement) and connecting that management goal to the specific assessment techniques in a logical and transparent way (that is, developing a clear set of assessment endpoints and measures of effects per risk assessment guidance);
4.4.4 Using unjustified or inappropriate exposure factors, toxicity parameters, or other assumptions required by an assessment technique or applying a model that is not supported by site-specific data;
4.4.5 Developing ecologically-based RBSLs from data that do not exhibit a dose- or concentration-response relationship, or failing to consider cumulative risks or additive effects when required to do so by jurisdiction-specific guidance;
4.4.6 Neglecting aesthetic, narrative, or other constraints when using RBSLs to establish the RAOs for a site;
4.4.7 Initiating remedial action(s) (other than an action taken to address imminent or priority issues) before determining the appropriate RAOs for the site. RAOs must be attainable using existing technology (that is, technically practicable and cost effective) and must reflect the desired long-term outcome for a sediment site in the context of current and realistic future site uses, as well as background concentrations and the potential for recontamination. It is also inappropriate to proceed with remedial action(s) without consideration of site source-control measures (due to the potential for recontamination from uncontrolled sources).
4.4.8 Limiting remedial action options to a single type of remedial technology, failing to consider options for remedial activity or failing to consider use limitations of remedial technologies. In all cases, a robust remedial options analysis that is not biased towards a particular remedial action option is needed;
4.4.9 Using an interim remedial action to delay the RBCA process rather than to reduce risk;
4.4.10 Failing to consider the impact of a potential remedial action on relevant receptors as part of the selection process;
4.4.11 Failing to consider the long-term effectiveness of a potential remedial action during the selection process, or failing to monitor the effectiveness of the option once selected and implemented; and
4.4.12 Continuing to monitor a site once the RAOs have been achieved (unless the RAOs were explicitly designed to involve such monitoring). (Guide E3164)
Scope
1.1 Sediment-RBCA is based on protecting human health and the environment. The guide supplements the RBCA (Guide E2081) and Eco-RBCA (Guide E2205/E2205M) processes and provides a decision-making process for the management of contaminated sediment. Contaminated sediment sites vary greatly in terms of setting, usage, spatial and temporal complexity, and physical and chemical characteristics; and, therefore, they also vary greatly in terms of the risk that they may pose to human health and the environment. The Sediment-RBCA recognizes this diversity by using a tiered approach for gathering and evaluating data to determine the need for additional evaluation or risk management tailored to site-specific conditions and risks.
1.2 This guide is intended to help direct and streamline the corrective action process and to complement (but not supersede) jurisdiction-specific guidance and regulations. It can be employed where jurisdiction-specific guidance is absent or insufficiently detailed; it can also assist to unify guidance when overlapping jurisdictions apply. It is compatible with a variety of programmatic guidelines for risk assessment and guidance from US Environmental Protection Agency (USEPA), Environment Canada, European, US states, that share the underlying risk assessment approach. In all applications, regulatory agencies should be consulted, as appropriate. Sediment-RBCA is not intended to apply to current permitted releases or permit applications.
1.3 There are numerous TPDs related to the Sediment-RBCA process. Common examples are defining DQOs, identifying relevant receptors, defining toxicity values for risk evaluation, determining target risk levels, specifying the appropriate statistics and sample sizes, determining exposure assumptions, determining when and how to account for cumulative risks and additive effects among chemical(s) of concern, addressing resource protection, along with remedial action constraints (RACs). It is not the intent of this guide to define appropriate TPDs. Users should be aware of jurisdiction-specific guidance and should seek approvals and/or technical policy input as applicable.
1.4 The general performance standard for this guide requires that:
1.4.1 TPDs will be identified early in the Sediment-RBCA process and reevaluated throughout the process (at each tier),
1.4.2 Data and information compiled during the Sediment-RBCA process, including historical data and new data collected during the site assessment, will be relevant to and of sufficient quantity and quality to answer the questions and support the decisions made at each tier of investigation,
1.4.3 Actions taken during the risk-based decision-making process will be protective of human health and the environment, consistent with current scientific principles and practices, and in accordance with jurisdiction-specific requirements (for example, regulations, policies, and guidance), and
1.4.4 Remedial actions implemented consistent with TPDs and the Sediment-RBCA process will not result in greater long-term risks than existed before taking actions.
1.5 There are basic elements common to all RBCA guides:
1.5.1 site assessment;
1.5.2 tiered evaluations of exposure, effects, and risk;
1.5.3 risk-based decision making;
1.5.4 remedial action, and
1.5.5 monitoring.
1.6 This Sediment-RBCA focuses on releases of chemicals from sediment and is intended to be a companion to Guides E1739, E2081, and E2205/E2205M. Risks to human health from contaminated sites are discussed in Guides E1739 and E2081, while risks to ecological receptors are discussed in Guide E2205/E2205M and Guide E2020.
1.7 Both human health and ecological resource risks from contaminated sediment are addressed in this guide. Guidance on conducting human health and ecological risk assessments is available, including from various regulatory agencies, published literature, and scientific associations (see Appendix X1 to Appendix X7, Guide E2205/E2205M, and Guide E2020).
1.8 For sites that warrant remedial action, guidance is provided on developing remedial Action Objectives (RAOs) (Appendix X7) that support a remedial action plan.
1.9 This guide is organized as follows:
1.9.1 Section 2 lists referenced ASTM documents;
1.9.2 Section 3 defines terminology used in this guide;
1.9.3 Section 4 describes the significance and use of this guide;
1.9.4 Section 5 describes the tiered approach to the Sediment-RBCA process;
1.9.5 Sections 6 and 7 present Sediment-RBCA procedures in a step-by-step process; and
1.9.6 The reference section lists documents cited in this guide.
1.10 This guide also includes the following appendices, which are provided as supplemental information:
1.10.1 Appendix X1: Considerations for Design and Execution of Weight of Evidence (WOE) Approaches in Sediment Risk Assessment;
1.10.2 Appendix X2: Use of Sediment Quality Guideline Values (SQGs) in Screening Level Ecological Risk Assessments (SLERAs);
1.10.3 Appendix X3: Derivation and Use of Site-specific Ecological Criteria (SSEC) in Ecological Risk Assessments;
1.10.4 Appendix X4: Uncertainty in Risk Evaluation;
1.10.5 Appendix X5: Application of Reference Area Data in Sediment Ecological Risk Assessment;
1.10.6 Appendix X6: Biological Test Methods, and
1.10.7 Appendix X7: Guidance for Developing RAOs.
1.11 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.
1.12 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
