1.1 This guide describes data visualization, statistical, forensic chemistry and geochemical methodologies (including case studies) used in the evaluation of candidate background data sets; this evaluation leads to the development of representative background data sets for the sediment site. Statistical methodologies can then be applied to the representative background data sets to develop background threshold values (BTVs) that are measures of the upper limit of representative sediment background concentrations for the sediment site. In addition, representative background data sets and sediment site data sets can be compared using two-sample statistical tests to determine if there are statistically significant differences (at a specified confidence level) between the two data sets (such as, the median or mean values of the two data sets are significantly different).

1.2 Technically defensible representative sediment background concentrations are critical for several purposes (1).2 These include sediment site delineation, establishing remedial goals and cleanup levels, remedy selection, assessment of risks posed by representative background concentrations, and establishing appropriate post-remedial monitoring plans.

1.3 The overarching framework for the development of representative sediment background concentrations at sediment sites is presented in Guide E3382. Guide E3240 provides a general discussion of how conceptual site model (CSM) development fits into the risk-based corrective action framework for contaminated sediment sites, while Guide E3382 provides a detailed discussion of the elements of a sediment site CSM that need to be considered when developing representative sediment background concentrations. Guide E3344 describes how to select an appropriate background reference area(s) from which to collect sediment samples for laboratory analysis. Guide E3164 describes the sampling methodologies to obtain sediment samples in the field (whether from the sediment site or background reference area[s]), while Guide E3163 discusses appropriate laboratory methodologies for the chemical analysis of potential contaminants of concern (PCOCs) in the sediment samples. Relevant content contained in Guides E3344 and E3382 is summarized herein, but the individual guides should be consulted for more detailed coverage of these topics.

1.4 This guide focuses on the approach for the development 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, tribal, 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 being performed should be reviewed to confirm compliance.

1.5 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 of concern (COCs) that exceed risk-based thresholds have been identified.

1.6 Units—The values stated in SI or CGS units are to be regarded as standard. No other units of measurement are included in this standard.

1.7 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.

1.8 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.