Standard Guide for Non-Aqueous Phase Liquid (NAPL) Mobility and Migration in Sediment—Sample Collection, Field Screening, and Handling

Importancia y uso:

4.1 Intended Users: 

4.1.1 This guide may be used by various parties involved in programs evaluating the movement of NAPL in sediment, including regulatory agencies, project sponsors, environmental consultants, risk assessors, site remediation professionals, environmental contractors, environmental contractors, analytical testing laboratories, data reviewers and users, and other stakeholders, which may include (but are not limited to) owners, buyers, developers, lenders, insurers, government agencies, and community members and groups.

4.1.2 This guide does not replace the need for engaging competent persons to collect, field screen, and handle sediment samples for use in the evaluation of NAPL mobility and migration in sediment. Activities described in this guide should be conducted by persons familiar with NAPL-impacted sediment site characterization techniques, as well as sediment NAPL movement assessment protocols. The users of this guide should consider assembling a team of experienced professionals (4.1.1) with appropriate expertise to scope, plan, and execute sediment NAPL data acquisition activities.

4.2 Reference Materials: 

4.2.1 This guide should be used in conjunction with other ASTM guides listed in 2.1 (especially Guides E3248, E3281, and E3282), as well as the material in the References section.

4.3 Flexible Site-Specific Implementation: 

4.3.1 Demonstrating the potential for movement of NAPL in sediment to regulators and other stakeholders has been historically hampered by the lack of standardized terminology and characterization protocols. The complexity of NAPL movement in sediment, and the historical lack of agreed upon methods for analyzing and interpreting site data, have led to uncertainty in corrective action decision-making, which has sometimes resulted in misleading expectations about remedial outcomes.

4.3.2 Assessment of NAPL movement in sediment is an evolving science. This guide provides a systematic, yet flexible, guidance on sample collection, sample field screening, and sample handling to accommodate variations in approaches by regulatory agencies and users, based on project objectives, site complexity, unique site features, programmatic and regulatory requirements, newly developed guidance, newly published scientific research, use of alternative scientifically based methods and procedures, changes in regulatory criteria, advances in scientific knowledge and technical capability, multiple LOEs approach, and unforeseen circumstances.

4.4 Regulatory Frameworks: 

4.4.1 This guide is to inform, complement, and support (but not supersede) the requirements or guidelines established by local, state, tribal, federal, or international agencies. As such, this guide does not provide a detailed discussion of the requirements or guidance associated with any of these jurisdictions, nor is it intended to supersede applicable regulations and guidance. Users of this guide will need to be aware of (and comply with) the regulatory requirements and guidance in the jurisdiction where the work is being performed.

4.4.2 This guide may be used to support existing regulatory requirements or guidelines for collecting, field screening, and handling sediment samples used to evaluate NAPL mobility and migration in sediment.

4.5 Systematic Project Planning and Scoping Process: 

4.5.1 When applying this guide, users 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. These practitioners should have the appropriate expertise to scope, plan, and execute a sediment corrective action program. This team may include (but is not limited to) the personnel outlined in 4.1.1.

4.6 Stakeholder Engagement: 

4.6.1 Users of this guide are encouraged to engage key stakeholders early and often in the project planning and scoping process, especially regulators, project sponsors, and service providers. A concerted, ongoing effort should be made by users to continually engage regulators and other relevant stakeholders as the project progresses to gain insight, technical support, and input for resolving technical issues and challenges that may arise during project implementation.

4.7 Importance of NAPL Movement Assessments: 

4.7.1 The movement (or lack of movement) of NAPL in sediment is a key factor in developing protective remedial options for NAPL-impacted sediment and for the long-term management of sediment sites. Typical exposure pathways that are addressed through risk management decisions at upland sites are usually not applicable to sediment sites. Rather, “contaminants in the biologically active layer of the surface sediment at a site often drive exposure,” (1)6 because in aquatic environments, benthic organisms live in the surface sediment to maintain access to oxygenated overlying surface water. NAPL that is present in subsurface sediment below the biologically active zone (BAZ) that is not migrating (that is, NAPL that is stable at the NAPL body scale) and has overlying sediment that is expected to remain in place (that is, the sediment will not be dredged or eroded) typically does not pose a risk to human or ecological receptors, because there is no pathway for exposure other than transport of dissolved-phase contaminants from the buried NAPL source to the BAZ. Removal of stable NAPL may not be warranted during remedial actions if (1) risks from dissolved-phase contaminants originating from this stable NAPL have been evaluated and found to be acceptable or (2) unacceptable risks from the dissolved-phase contaminants can be adequately mitigated (such as by the placement of an amended cap). Thus, understanding NAPL presence, extent, and potential movement is a key factor in managing contaminated sediment sites.

4.8 Application of This Guide: 

4.8.1 The use of this guide is consistent with the sediment risk-based corrective action (RBCA) process (Guide E3240) that guides users to acquire and evaluate appropriate data and use each piece of data to refine goals, objectives, receptors, exposure pathways, and the CSM. As the sediment RBCA process proceeds, data and conclusions reached at each stage help to focus subsequent evaluations. This integrated process results in efficient, cost-effective decision-making and timely, appropriate response actions for NAPL-impacted sediment. This guide is not intended to provide specific guidance on sediment site risk assessment, monitoring, or remedial action.

4.9 Structure and Components of This Guide: 

4.9.1 Users of this guide should review the overall structure and components of this guide before proceeding with use, including:

Section 1 - Scope

Section 2 - Referenced Documents

Section 3 - Terminology

Section 4 - Significance and Use

Section 5 - NAPL Mobility Field Investigation Overview

Section 6 - Sediment Sample Collection Methods

Section 7 - Sediment Sample Field Screening Methods

Section 8 - Sediment Sample Handling, Storage, and Transport Methods

Section 9 - Keywords

Appendix X1 - Additional Sediment Sample Collection Considerations

Appendix X2 - Case Study

References

Subcomité:

E50.04

Referida por:

E3281-21A, E3248-25

Volúmen:

11.05

Número ICS:

13.080.01 (Soil quality and pedology in general)

Palabras clave:

contaminated sediment; field screening; migration; mobility; NAPL; sampling; sediment;