ASTM E3268-21 PDF

SIGNIFICANCE AND USE 4.1 Many contaminants, including chlorinated solvents and petroleum products, enter the subsurface in the form of an immiscible liquid, known as a NAPL. Understanding the potential emplacement and transport mechanism for NAPL in sediment is an important element of an overall conceptual site model (CSM) that forms a basis for (1) investigating the nature and extent of NAPL, (2) evaluating if (and how) human and ecological receptors may be exposed to NAPL, and (3) assessing remedial alternatives. In addition, demonstrating the potential movement of NAPL in sediments is hampered by the lack of standardized terminology and characterization protocols, thus necessitating this guide. 4.1.1 Understanding the presence and movement of NAPL in sediments is complicated by the lack of standardized protocols for characterizing NAPL movement in the diverse range of sediment environments. Literature searches have indicated that there is a limited body of available, applicable research. Current research has focused on site-specific sediment NAPL mobility assessment approaches, but application of common methods or decision-making processes identified across sites were limited. 4.1.2 The movement (or lack of movement) of NAPL in sediments is a key factor in developing protective remedial options for NAPL-impacted sediments 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)5, because in aquatic environments, benthic organisms live in the surface sediment to maintain access to oxygenated overlying water. NAPL that is present in subsurface sediment below the biologically active layer that is not migrating and has an overlying sediment that is expected to remain in place (that is, is not dredged or eroded) does not pose a risk to ... SCOPE 1.1 This guide provides considerations to inform sample collection, field screening, and sample handling of sediments impacted with non-aqueous phase liquid (NAPL) to assist in data collection for the evaluation of NAPL movement in sediment. The conditions affecting NAPL emplacement and movement in sediments are significantly different than in upland soils. As such, the framework for the assessment of NAPL movement in upland soils has been determined to have limited applicability for sediments. 1.2 This guide is applicable to sediment sites where the presence or suspected presence of NAPL has been identified. Sediments are the subject media considered in this guide, not surface water or groundwater. 1.3 The goal of this guide is to provide a technical framework for sample collection, field screening, and sample handling activities used to evaluate NAPL conditions, in particular NAPL movement (that is, mobility at the pore scale and migration at the NAPL body scale) in sediments, which can be used to inform the development and selection of remedial options and post-remedial monitoring activities. 1.4 This guide discusses sample collection procedures, including direct methods (that is, core and grab samples) and indirect methods (that is, DART®2, laser-induced florescence, and porewater samplers) for assessing NAPL presence or absence in sediment. 1.5 This guide discusses field characterization procedures for assessment of NAPL-impacted sediments including visual screening, stratification assessment, shake test, ultraviolet (UV) light test, NAPL FLUTe™3, and headspace vapor monitoring. 1.6 This guide discusses considerations to obtain samples representative of in situ conditions. This includes methods used to evaluate sediment integrity, sample retrieval from the sediment bed, core identification, sample storage onboard the vessel, sample retrieval from the coring device, sufficient sample recovery, core cut...