Significance and Use 4.1 Intended Use: This guide may be used by various parties involved in sediment corrective action programs, including regulatory agencies, project sponsors, environmental consultants, toxicologists, risk assessors, site remediation professionals, environmental contractors, and other stakeholders. 4.2 Related ASTM Standards: This guide is related to Guide E3164, which addresses corrective action monitoring before, during, and after sediment remediation activities; as well as Guide E3163, concerning sediment analytical techniques used during sediment programs. 4.3 Use of Representative Background to Set a Boundary: Representative background concentrations for sediments can be used to delineate a sediment corrective action, establishing the boundary of the sediment corrective action by distinguishing site-related impacts from representative background concentrations. 4.4 Use of Representative Background to Establish Cleanup Levels: Representative background concentrations for sediments can also be used to establish cleanup levels for use in sediment corrective actions. In cases where risk-based sediment cleanup levels are below representative background concentrations, background concentrations are typically used as the cleanup level. This ensures that the cleanup levels are sustainable. Any recontamination from ongoing sources will eventually result in surface sediment concentrations greater than the risk-based cleanup level, but the surface sediment should still meet a cleanup level based on representative background concentrations, even after recontamination. 4.5 Use of Representative Background in Risk Assessments: Representative background concentrations can be used in the risk assessment process (including human and ecological risk assessments) to understand risks posed by background levels of contaminants to human health and the environment, and the incremental risks posed by site-related releases and/or activities that result in sediment concentrations that exceed representative background concentrations. Conversely, they can be used to estimate the risk reduction for various contaminants, if sediment is remediated from existing PCOC concentrations to lower values (that is, representative background concentrations). 4.6 Use of Representative Background in Long-Term Monitoring Programs: Long-term monitoring programs can also use representative background concentrations in sediment, either as a corrective action target or to understand how post-corrective action concentrations compare to sources not attributable to site releases and/or activities. Typically, source control actions taken to ensure that site-related releases are controlled and will not re-contaminate the post-corrective action sediments must be developed based on an understanding of ongoing contributions from representative background. Ongoing sources not related to site-related releases and/or activities (that may or may not be subject to source control actions) must be considered in this evaluation. 4.7 Importance of the CSM: The users of this guide are encouraged to continuously update and refine the CSM used to describe the physical properties, chemical composition and occurrence, biologic features, and environmental conditions of the sediment corrective action project (Guide E1689). 4.8 Reference Material: This guide should be used in conjunction with other reference material (refer to Section 2 and References at the end of this guide) to direct the user in developing and implementing sediment corrective action programs. 4.9 Flexible Site-Specific Implementation: This guide provides a systematic, but flexible, framework to accommodate variations in approaches by regulatory agencies and by the user based on project objectives, site complexity, unique site features, regulatory requirements, newly developed guidance, newly published scientific research, changes in regulatory criteria, advances in scientific knowledge and technical capability, and unforeseen circumstances. 4.10 Systematic Project Planning and Scoping Process: When applying this guide, the user should undertake a systematic project planning and scoping process to collect information to assist in making site-specific, user-defined decisions for a particular project, including assembling an experienced team of project professionals (that is, experienced practitioners familiar with current sediment site characterization and remediation techniques, as well as geochemistry, and statistics). These practitioners should have the appropriate expertise to scope, plan, and execute a sediment data acquisition and analysis program. This team may include, but is not limited to, project sponsors, environmental consultants, toxicologists, site remediation professionals, analytical chemists, geochemists, and statisticians.Scope 1.1 This guide focuses on the approach for determination of representative sediment background concentrations used for remedial actions performed under various regulatory programs, including the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA). Although many of the references cited in this guide are CERCLA oriented, the guide is applicable to remedial actions performed under local, state, federal, and international cleanup programs. However, the guide does not describe requirements for each jurisdiction. The requirements for the regulatory entity under which the cleanup is performed should be reviewed to confirm compliance. 1.2 This guide provides a framework, including specific statistical and geochemical considerations, as well as case studies, demonstrating the approach to determine representative sediment background concentrations. This guide is intended to inform, complement, and support, but not supersede, local, state, federal, or international regulations. 1.2.1 This guide does not address methods and means of data collection (Guide E3163, Guide E3164.) 1.2.2 This guide is designed to apply to contaminated sediment sites where sediment data have been collected and are readily available. Additionally, this guide assumes that risk assessments have been performed, so that the contaminants/chemicals of interest that exceed risk-based thresholds have been identified. 1.2.3 Furthermore, this guide presumes that risk-based thresholds identified are low enough to pose corrective action implementation challenges, and/or the site is subject to recontamination from ongoing anthropogenic and/or natural sources that are not controlled. In both cases, representative sediment background concentrations will be useful for determining the extent of corrective remedial actions (when used as remedial goals), evaluating risks posed by representative background concentrations, and establishing appropriate post-remedial monitoring plans. 1.3 Units—The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard. 1.4 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. 1.5 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.
