ASTM E 3268 : 2025

1.1Many contaminants (such as petroleum products and coal tar) are emplaced in sediment in the form of an immiscible liquid, known as a non-aqueous phase liquid (NAPL). NAPL can either be a light non-aqueous phase liquid (LNAPL) that is less dense than water or a dense non-aqueous phase liquid (DNAPL) that is denser than water. To develop an overall conceptual site model (CSM) for a sediment site, it is important to (1) investigate the nature and extent of NAPL in the sediment, and (2) evaluate if (and how) human and ecological receptors may be exposed to NAPL (such as by the advective movement of the NAPL in the sediment).

1.2This guide is applicable for a wide range of sediment sites where NAPL is present or suspected to be present. The conditions affecting NAPL emplacement and movement in sediment are typically significantly different than in upland soils (Guide E3248).

1.3Understanding the movement of NAPL in sediment was historically complicated by the lack of standardized protocols for characterizing NAPL movement in the diverse range of sediment environments. Any NAPL movement evaluation approaches historically used were site-specific in nature, but no common methods or decision-making frameworks were available to consistently use at various sediment sites. To address these issues, this guide and three associated guides (Guides E3248, E3281, and E3282) addressing the advective movement of NAPL in sediment have been developed.

1.4This guide describes sample collection, sample field screening, and sample handling of sediment containing NAPL to assist in data collection to evaluate NAPL movement in sediment and to characterize the presence and extent of NAPL in the sediment.

1.5The goal of this guide is to provide a technical framework for sample collection, sample field screening, and sample handling activities used when collecting sediment samples to evaluate NAPL conditions, in particular NAPL movement (that is, NAPL mobility at the pore scale and NAPL migration at the NAPL body scale) in sediment using a multiple lines of evidence (LOEs) approach (Guide E3282). The results of NAPL movement assessments (Guide E3248) can be used to inform the development and selection of remedial options and post-remedial monitoring activities.

1.6This guide discusses direct sample collection methods (that is, core and grab samples) and indirect investigation methods (that is, DART^® systems,2 laser-induced florescence (LIF) methodologies, and porewater samplers) for assessing NAPL presence or absence in sediment.

1.7This guide discusses field screening methods to assess NAPL-impacted sediment including visual observations, stratification observation, sediment-water shake tests, ultraviolet (UV) light, NAPL FLUTe^TM3 and organic vapor monitor (OVM) screening.

1.8This guide discusses sample handling considerations to obtain sediment samples representative of in situ conditions. This includes methods used to deploy and retrieve the sediment sampling device, evaluate sediment sample acceptability and integrity, characterize core sample recovery, identify samples, temporarily store samples for later processing, cut cores, remove samples from the sampling device, and freeze or cool sediment samples. Methods to be used will depend on site-specific considerations.

1.9Petroleum hydrocarbon, coal tar, and other tar NAPLs (including fuels, oils, and creosote) are the primary focus of this guide. These forms of contamination are commonly related to historical operations at petroleum refineries, petroleum distribution terminals, manufactured gas plants, and various large industrial sites.

1.10Related ASTM Standards—This guide is related to several other guides that cover various aspects of NAPL mobility and migration in sediment. Guide E3248 provides guidance on NAPL emplacement mechanisms in sediment and the differences between NAPL in sediment and upland soils; this guide also outlines a framework to be used to determine whether a NAPL Movement Assessment should be performed at a sediment site. Guide E3281 discusses the use of field screening methodologies as part of a framework to select sediment samples to be submitted for laboratory NAPL mobility testing. Guide E3282 discusses metrics (for various LOEs) to evaluate whether NAPL is mobile or immobile at the pore scale and (if the NAPL is mobile) describes other metrics (using additional LOEs) to evaluate whether NAPL is migrating or stable at the NAPL body scale. Guide E3282 also presents example decision analysis frameworks for ascertaining if NAPL is mobile at the pore scale or migrating at the NAPL body scale (or both). Guide E3300 discusses ebullition fundamentals and how to measure ebullition-facilitated transport (EFT) fluxes for NAPL and associated contaminants (which can be used to estimate NAPL/contaminant loadings to the surface water body). Guide E3447 discusses the use of flux chambers to measure EFT fluxes and estimate NAPL/contaminant loadings to the water body.

1.11Units—The values stated in SI or CGS units are to be regarded as the standard. No other units of measurement are included in this standard.

1.12This 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.

1.13This 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.