1.1 本指南旨在广泛应用于存在或怀疑存在非水相液体（NAPL）的各种沉积物场所。本指南描述了可能导致沉积物地层剖面中存在NAPL的多种侵位机制，以及沉积物特征、水环境和NAPL特性如何影响沉积物中的NAPL运动。本指南提供了沉积物中NAPL侵位的示例概念模型，以建立一个通用框架，用于评估通过平流影响NAPL移动的条件。 1.2 本指南补充了根据国际、联邦、州和地方环境计划进行的表征和补救工作的方法，但并不取代监管机构的要求。 本指南的用户应审查沉积物现场的现有信息和数据，以确定适用的监管机构要求以及本指南的最合适入口和使用。 1.3 ASTM标准指南不是法规；它们是共识标准指南，可自愿遵循，以支持适用的监管要求。本指南可与其他为评估沉积物位置而制定的ASTM指南结合使用。 1.4 单位- 以国际单位制表示的数值应视为标准。本标准不包括其他计量单位。 1.5 本标准并非旨在解决与其使用相关的所有安全问题（如有）。 本标准的用户有责任在使用前制定适当的安全、健康和环境实践，并确定监管限制的适用性。 1.6 本国际标准是根据世界贸易组织技术性贸易壁垒（TBT）委员会发布的《关于制定国际标准、指南和建议的原则的决定》中确立的国际公认标准化原则制定的。 ====意义和用途====== 4.1 了解NAPL在沉积物中的潜在侵位和运输机制是构成整体概念场地模型（CSM）的一个重要元素，该模型为 (1) 调查NAPL的性质和范围， (2) 评估人类和生态受体是否（以及如何）暴露于NAPL，以及 (3) 评估补救方案。此外，由于缺乏标准化的术语和表征协议，向监管机构和其他利益相关者证明沉积物中NAPL的潜在移动一直受到阻碍。沉积物中NAPL运动的复杂性，以及缺乏商定的现场数据分析和解释方法，导致了纠正措施决策的不确定性。这有时会导致对补救结果的误解。由于沉积物和高地环境之间存在各种物理、地球化学和生物差异，NAPL在沉积物中的侵位和运输机制不同于高地环境中的侵位和运输机制，因此需要本指南。 4.2 本指南旨在补充根据《污染场地概念性场地模型指南》中概述的原则开发的CSM E1689 ，轻型非水相液体（LNAPL）现场用CSM开发的标准指南 E2531 ，以及基于风险的纠正措施（RBCA）指南 E1739 和 E2081年 通过考虑沉积物环境特有的NAPL侵位和运动条件（即平流）。本指南将帮助用户了解影响沉积物中NAPL发生和行为的沉积物环境的独特和基本特征。了解沉积物中NAPL的来源、NAPL在沉积物中的侵位机制以及影响NAPL在沉积物柱内平流运动的场地特征，将有助于确定调查这些条件所需的具体数据要求，并为补救决策提供可靠依据。 4.2.1 平流传输是本指南中讨论的主要NAPL迁移机制。 4.2.2 除了平流输送外，生物气泡在沉积物中移动（即沸腾）也可能促进NAPL迁移；然而，这一过程超出了本指南的范围。 4.2.3 与侵蚀引起的NAPL移动相关的过程（例如，propwash）不在本指南的范围内。 4.3 本指南描述了侵位机制和平流过程，并确定了技术可靠和全面的CSM所需的相关信息，以支持沉积物中NAPL的调查和/或修复。 技术上可靠和全面的CSM将导致对沉积物中NAPL进行更有效和一致的调查（例如，评估与沉积物中NAPL相关的风险，和/或补救决定）。评估沉积物中NAPL的存在和流动性的关键因素包括 (1) 水文环境， (2) 沉积物的物理和化学特征， (3) NAPL的物理和化学特性，以及 (4) NAPL区域的物理范围。本指南未涉及收集此类信息的手段和方法，包括评估沉积物中NAPL的流动性。 4.4 许多污染物（例如氯化溶剂、石油产品和杂酚油）以不混溶液体（即NAPL）的形式进入地下。 NAPL可以作为与水分离的相流动。如果NAPL的密度大于水（称为致密非水相液体，或DNAPL），则它会在重力的影响下下沉。如果液体密度低于水（称为轻非水相液体，或LNAPL），它将浮在水上。 4.5 本指南为沉积物环境中NAPL运动的初步评估提供了逻辑框架。它将帮助用户了解影响NAPL移动的物理条件和定位机制，并帮助确定收集数据的优先方法，以支持CSM的开发。 4.5.1 沉积物现场NAPL的CSM元素描述了环境的物理和化学特性、水力条件、NAPL的来源、侵位机制以及NAPL区的性质和范围。 CSM是一个动态的、不断发展的模型，随着新数据的收集和评估以及/或由于自然或工程过程导致的现场物理条件变化，该模型将随着时间而变化。CSM的目标是充分详细地描述NAPL的性质、分布和设置，以便能够充分解决有关当前和潜在未来风险、寿命和补救措施适应性的问题。 4.5.2 NAPL沉积物场地CSM的独特元素（与高地NAPL场地相比）包括但不限于: (1) 沉积物和水体的特征。 （a） 物理特性 :水文学（例如，河流水流、潮汐条件）、沉积学（例如，原生水体底部特征、沉积沉积物特征、沉积速率、侵蚀力）和水文地质学（例如，地下水）- 地表水相互作用）。 （b） 地球化学: 例如，氧化还原条件 （c） 生物学特性: 例如，底栖生物群落的存在 (2) NAPL释放的特征，包括影响NAPL在沉积物中侵位条件的地表水和沉积物特有的来源、机制和时间。 (3) NAPL在沉积物中的侵位机制，包括: （a） 高地源的平流输送， （b） 直接释放到地表水的合格沉积物表面上的沉积，可能因沉积物沉积而埋藏（仅适用于DNAPL），以及 （c） OPA的形成和沉积，可能因沉积物沉积而埋藏。 (4) NAPL潜在存在和范围的指标，包括观察水体内的渗漏、水滴和/或光泽。 (5) 人类和生态暴露于沉积物中NAPL或通过NAPL释放到上覆地表水的可能性。 4.6 在继续使用之前，本指南的用户应查看本指南的整体结构和组件，包括: 4.6.1 部分 1. – 范围 4.6.2 部分 2. – 参考文件； 4.6.3 部分 3. – 术语 4.6.4 部分 4. – 意义和用途； 4.6.5 部分 5. – 沉积物位置的独特方面； 4.6.6 部分 6. – NAPL侵位机制； 4.6.7 部分 7. – NAPL运动决策分析框架； 4.6.8 部分 8. – 关键词； 4.6.9 附录X1 – 侵位模型:地表水边界的潜在NAPL相互作用和对NAPL运动的影响； 4.6.10 附录X2 – 沉积过程和地下水-地表水相互作用； 4.6.11 附录X3 – NAPL运动术语。 4.7 本指南概述了影响水生沉积物环境中NAPL存在和潜在移动的独特特征。本指南无意为沉积物现场调查、风险评估、监测或补救行动提供具体指导。 4.7.1 本指南可供沉积物现场相关各方使用，包括监管机构、项目发起人、环境顾问、现场修复专业人员、环境承包商、分析测试实验室、数据审查员和用户以及其他利益相关者。 4.7.2 本指南并不取代聘请合格人员评估NAPL在沉积物中的侵位和移动的需要。开发CSM所需的活动应由熟悉NAPL影响的沉积物现场表征技术、NAPL在沉积物中的物理和化学特性、归宿和运输过程、修复技术和沉积物评估协议的人员进行。本指南的用户应考虑组建一个由经验丰富、具有适当专业知识的项目专业人员组成的团队，以确定范围、规划和执行沉积物NAPL数据采集活动。

1.1 This guide is designed for general application to a wide range of sediment sites where non-aqueous phase liquid (NAPL) is present or suspected to be present. This guide describes multiple emplacement mechanisms that can result in NAPL presence within the sediment stratigraphic profile and how the characteristics of the sediment, aquatic environment, and NAPL properties influence NAPL movement within sediments. This guide provides example conceptual models for NAPL emplacement in sediments in order to establish a common framework that can be used to assess conditions influencing NAPL movement by means of advection. 1.2 This guide supplements methodologies for characterization and remedial efforts performed under international, federal, state and local environmental programs, but does not replace regulatory agency requirements. The users of this guide should review existing information and data available for a sediment site to determine applicable regulatory agency requirements and the most appropriate entry point into and use of this guide. 1.3 ASTM standard guides are not regulations; they are consensus standard guides that may be followed voluntarily to support applicable regulatory requirements. This guide may be used in conjunction with other ASTM guides developed for assessing sediment sites. 1.4 Units— The values stated in SI units are to be regarded as the standard. No other units of measurement are included in this standard. 1.5 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. 1.6 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. ====== Significance And Use ====== 4.1 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 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 lack of agreed upon methods for analysis and interpretation of site data, has led to uncertainty in corrective action decision-making. This has sometimes resulted in misleading expectations about remedial outcomes. The emplacement and transport mechanisms for NAPL in sediments are different from those in upland environments, due to a variety of physical, geochemical, and biological differences between sediment and upland environments, thus necessitating this guide. 4.2 This guide is intended to supplement the CSM developed according to the principles outlined in the contaminated sites conceptual site model Guide E1689 , the standard guide for developing a CSM for Light Non-Aqueous Phase Liquid (LNAPL) sites Guide E2531 , and the Risk-Based Corrective Action (RBCA) Guides E1739 and E2081 , by considering conditions for NAPL emplacement and movement (that is, advection) that are unique to a sediment environment. This guide will aid users in understanding the unique and fundamental characteristics of sediment environments that influence the occurrence and behavior of NAPL in sediments. Understanding the sources of NAPL encountered in sediment, the mechanisms for NAPL to become emplaced in sediments, and the site characteristics that influence the advective movement of NAPL within the sediment column will aid in identifying specific data requirements necessary to investigate these conditions and to provide a sound basis for remedy decisions. 4.2.1 Advective transport is the primary NAPL migration mechanism that is addressed within this guide. 4.2.2 In addition to advective transport, biogenic gas bubbles moving through sediments (that is, ebullition) may also facilitate NAPL migration; however, this process is beyond the scope of this guide. 4.2.3 Processes associated with NAPL movement due to erosion (for example, propwash) are not within the scope of this guide. 4.3 This guide describes the emplacement mechanisms and advective processes, and identifies the relevant information necessary for a technically reliable and comprehensive CSM in support of the investigation and/or remediation of NAPL in sediments. A technically reliable and comprehensive CSM will result in more efficient and consistent investigation of NAPL in sediments (for example, assessment of risks associated with NAPL in sediment, and/or remedy decisions). The key elements in assessing the presence and mobility of NAPL in sediment include (1) the hydrological setting, (2) the physical and chemical characteristics of the sediment, (3) the physical and chemical characteristics of the NAPL, and (4) the physical extent of the NAPL zone. The means and methods for collecting this information, including evaluating the mobility of NAPL in sediments, is not addressed in this guide. 4.4 Many contaminants (for example, chlorinated solvents, petroleum products and creosote) enter the subsurface as an immiscible liquid, known as NAPL. NAPLs may flow as a separate phase from water. If the NAPL is denser than water (known as dense non-aqueous phase liquid, or DNAPL), it will sink under the influence of gravity. If the liquid is less dense than water (known as a light nonaqueous phase liquid, or LNAPL), it will float on water. 4.5 This guide provides a logical framework for the initial assessment of NAPL movement in sediment environments. It will help users understand the physical conditions and emplacement mechanisms that influence NAPL movement and aid in prioritizing methods for gathering data to support development of a CSM. 4.5.1 The elements of a CSM for NAPL at sediment sites describe the physical and chemical properties of the environment, the hydraulic conditions, the source of the NAPL, the emplacement mechanisms, and the nature and extent of the NAPL zone. The CSM is a dynamic, evolving model that will change through time as new data are collected and evaluated and/or as physical conditions of the site change due to natural or engineered processes. The goal of the CSM is to describe the nature, distribution, and setting of the NAPL in sufficient detail, so that questions regarding current and potential future risks, longevity, and amenability to remedial action can be adequately addressed. 4.5.2 The unique elements for a CSM for a NAPL sediment site (compared to an upland NAPL site) include, but are not limited to: (1) Characteristics of the sediment and water body. (a) Physical characteristics : hydrology (for example, river currents, tidal conditions), sedimentology (for example, native water body bottom characteristics, deposited sediment characteristics, sedimentation rates, erosive forces), and hydrogeology (for example, groundwater-surface water interactions). (b) Geochemical: for example, redox conditions (c) Biological characteristics: for example, presence of benthic community (2) Characteristics of the NAPL release(s) including sources, mechanisms, and timing unique to surface water and sediment that affect the conditions under which the NAPL was emplaced in the sediment. (3) Mechanisms of NAPL emplacement in sediments, which include: (a) Advective transport from upland sources, (b) Deposition on a competent sediment surface from direct releases to surface water, with potential burial by sediment deposition (applies to DNAPL only), and (c) Formation and deposition of OPAs, with potential burial by sediment deposition. (4) Indicators for the potential presence and extent of NAPL, including observance of seeps, droplets and/or sheens within a water body. (5) The potential for human and ecological exposures to NAPL in sediment or by means of NAPL release to overlying surface water. 4.6 The user of this guide should review the overall structure and components of this guide before proceeding with use, including: 4.6.1 Section 1 – Scope; 4.6.2 Section 2 – Referenced Documents; 4.6.3 Section 3 – Terminology; 4.6.4 Section 4 – Significance and Use; 4.6.5 Section 5 – Unique Aspects of Sediment Sites; 4.6.6 Section 6 – NAPL Emplacement Mechanisms; 4.6.7 Section 7 – NAPL Movement Decision Analysis Framework; 4.6.8 Section 8 – Keywords; 4.6.9 Appendix X1 – Emplacement Models: Potential NAPL Interactions at Surface Water Boundaries and Effects on NAPL Movement; 4.6.10 Appendix X2 – Sedimentary Processes and Groundwater – Surface Water Interactions; 4.6.11 Appendix X3 – NAPL Movement Terminology. 4.7 This guide provides an overview of the unique characteristics influencing the presence and potential movement of NAPL in aquatic sediment environments. This guide is not intended to provide specific guidance on sediment site investigation, risk assessment, monitoring or remedial action. 4.7.1 This guide may be used by various parties involved in a sediment site, including regulatory agencies, project sponsors, environmental consultants, site remediation professionals, environmental contractors, analytical testing laboratories, data reviewers and users, and other stakeholders. 4.7.2 This guide does not replace the need for engaging competent persons to evaluate NAPL emplacement and movement in sediments. Activities necessary to develop a CSM should be conducted by persons familiar with NAPL impacted sediment site characterization techniques, physical and chemical properties of NAPL in sediments, fate and transport processes, remediation technologies, and sediment evaluation protocols. The users of this guide should consider assembling a team of experienced project professionals with appropriate expertise to scope, plan, and execute sediment NAPL data acquisition activities.