Standard Guide for Risk-Based Corrective Action for Contaminated Sediment Sites

Importancia y uso:

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)

Subcomité:

E50.04

Referida por:

E2020-22, E3377-24, E3242-23, E2081-22, E3382-24, E2205_E2205M-22, E3344-24, E3163-24, E3164-23

Volúmen:

11.05

Número ICS:

71.020 (Production in the chemical industry)

Palabras clave:

corrective action; ecological risk; human health risk; remedial action; risk-based corrective action; sediment; site assessment; technical policy decisions; tiered approach;