1.1 本规程描述了用于从井中收集地下水样本以评估地下水质量的低流量清洗和采样方法。 1.2 该程序的目的是收集地下水样本，代表在环境条件下通过井网附近地层输送的溶质和胶体浓度的流量加权平均值。使用这种方法采集的样品可以分析地下水污染物和/或自然产生的分析物。 1.3 这种做法通常不适用于产量极低的油井，不能使用抓取取样或惯性提升装置进行。这种做法不适用于含有非水相液体的油井。 1.4 单位- 以国际单位制表示的数值应视为标准值。括号中给出的值是英寸-磅单位的近似数学转换，仅供参考，不被视为标准值。 1.5 本实践提供了一组用于执行一个或多个特定操作的说明。本文件不能取代教育或经验，应与专业判断一起使用。并非本惯例的所有方面都适用于所有情况。本ASTM标准不代表或取代必须根据其判断给定专业服务的充分性的谨慎标准，也不应在不考虑项目的许多独特方面的情况下应用本文件。标题中的“标准”一词仅表示该文件已通过ASTM共识程序获得批准。 1.6 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。 1.7 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====== 5.1 方法注意事项- 大多数地下水采样计划的目标是获得与井网附近地层水成分相似的样本。低流量吹扫和采样方法使用指标参数的稳定来确定何时将泵排量视为代表地层水的流量加权平均值。操作参数测量用于确定泵送操作可能引入的潜在采样偏差（例如，人为浊度和温度升高），并确保样本代表地层水。 低流量清洗速率最大限度地降低了环境地下水位，从而最大限度地减少了滤网上方或下方的空白立管（以及潜在的滞水）水夹带到油井屏蔽区的可能性。这种取样方法假设油井已按照实践中所述进行了适当的设计和建造 D5092/D5092M 和 D6725/D6725M ，如指南中所述充分开发 D5521/D5521M ，并已按照指南中的说明进行了适当的油井维护和修复 D5978/D5978M （参见 注1 ). 注1: 本标准无意取代或取代任何监管要求、标准操作程序（SOP）、质量保证项目计划（QAPP）、地下水采样和分析计划（GWSAP）或现场特定监管许可要求。本标准中描述的程序可与监管要求、SOP、QAPP、GWSAP或具有管辖权的机构允许的许可证一起使用。 5.2 适用性- 低流量吹扫和取样可用于监测井，该监测井可以以恒定的低流速泵送，而不会不断增加井内的压降 ( 2. ) . 如果即使在非常低的泵送速率下（例如，50–100毫升/分钟），也无法在不持续增加压降的情况下清洗油井，则不应使用本标准中所述的这种取样方法对油井进行取样；如指南中所述的被动采样方法 D7929 ，可作为替代方案。 5.3 目标分析物- 低流量吹扫和取样可用于收集各类水相污染物和天然分析物的样品。它特别适用于需要对可能吸附或分配到颗粒物的水相成分进行采样的情况，因为与使用泵、水罐或惯性泵的高流量/高容量清洗相比，该方法最大限度地降低了产生人为浑浊的可能性- 提升装置 ( 9- 12 ) .

1.1 This practice describes the method of low-flow purging and sampling used to collect groundwater samples from wells to assess groundwater quality. 1.2 The purpose of this procedure is to collect groundwater samples that represent a flow-weighted average of solute and colloid concentrations transported through the formation near the well screen under ambient conditions. Samples collected using this method can be analyzed for groundwater contaminants and/or naturally occurring analytes. 1.3 This practice is generally not suitable for use in wells with very low-yields and cannot be conducted using grab sampling or inertial lift devices. This practice is not suitable for use in wells with non-aqueous phase liquids. 1.4 Units— The values stated in SI units are to be regarded as standard. The values given in parentheses are approximate mathematical conversions to inch-pound units that are provided for information only and are not considered standard. 1.5 This practice offers a set of instructions for performing one or more specific operations. This document cannot replace education or experience and should be used in conjunction with professional judgment. Not all aspects of this practice may be applicable in all circumstances. This ASTM standard is not intended to represent or replace the standard of care by which the adequacy of a given professional service must be judged, nor should this document be applied without consideration of a project's many unique aspects. The word “standard” in the title means only that the document has been approved through the ASTM consensus process. 1.6 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. 1.7 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 ====== 5.1 Method Considerations— The objective of most groundwater sampling programs is to obtain samples that are similar in composition to that of the formation water near the well screen. The low-flow purging and sampling method uses the stabilization of indicator parameters to determine when the pump discharge is considered to represent a flow-weighted average of the formation water. Measurements of operational parameters are used to determine potential sampling bias (for example, artifactual turbidity and increased temperature) that may have been introduced by pumping operations and to ensure that the sample is representative of formation water. The low-flow purge rate minimizes lowering of the ambient groundwater level and thereby minimizes potential entrainment of blank-riser pipe (and potentially stagnant) water above or below the screen into the screened-zone of the well. This sampling method assumes that the well has been properly designed and constructed as described in Practices D5092/D5092M and D6725/D6725M , adequately developed as described in Guide D5521/D5521M , and has received proper well maintenance and rehabilitation as described in Guide D5978/D5978M (see Note 1 ). Note 1: This Standard is not intended to replace or supersede any regulatory requirements, standard operating procedure (SOP), quality assurance project plan (QAPP), ground water sampling and analysis plan (GWSAP) or site-specific regulatory permit requirements. The procedures described in this Standard may be used in conjunction with regulatory requirements, SOPs, QAPPs, GWSAPs or permits where allowed by the authority with jurisdiction. 5.2 Applicability— Low-flow purging and sampling may be used in a monitoring well that can be pumped at a constant low-flow rate without continuously increasing drawdown in the well ( 2 ) . If a well cannot be purged without continuously increasing drawdown even at very low pumping rates (for example, 50 – 100 mL/min), the well should not be sampled using this sampling method as described in this standard; a passive sampling method, as described in Guide D7929 , may be considered as an alternative. 5.3 Target Analytes— Low-flow purging and sampling can be used to collect samples for all categories of aqueous-phase contaminants and naturally-occurring analytes. It is particularly well suited for use where it is desirable to sample aqueous-phase constituents that may sorb or partition to particulate matter, because the method minimizes the potential for artifactual turbidity compared with high flow/high volume purging using a pump, bailer, or inertial-lift device ( 9- 12 ) .