1.1 本指南回顾了通过使用直接推动法插入地下水采样装置在离散点或增量进行地下水采样的方法( D6286/D6286M ，见3.3.2）。通过直接推动取样器，土壤被置换，并有助于在取样区上方形成环形密封。直接推动式水采样可以是一次或多次采样事件。要使用这些设备成功获取地下水样本，必须了解现场特定的地质和水文地质条件。 1.2 地下水水质和地质水文研究采用直接推进法进行水样采集。 根据地质水文条件，地表以下不同深度的水质和渗透性可能不同。增量采样或离散深度采样用于确定污染物的分布，并更完整地描述地质水文环境。在描述危险和有毒废物场地以及进行地质水文研究时，经常建议进行这些勘探。 1.3 本指南涵盖了几种类型的地下水采样器；密封筛网取样器、剖面取样器、双管取样系统和简单暴露筛网取样器。 通常，驱动至离散深度的密封滤网取样器可提供最高质量的水样。使用在采样事件之间清除的暴露屏幕的分析采样器允许在多个深度更快速地采集样本。如果将简单暴露的筛网取样器驱动至试验区，且在取样前未进行吹扫，则如果暴露于上部污染区，可能会导致更可疑的水质，在这种情况下，将被视为筛网装置。 1.4 介绍了获取地下水样本用于水质分析和污染物检测的方法。 这些方法包括使用相关标准，例如:；吹扫和取样装置的选择（指南 D6452 和 D6634/D6634M )，采样方法（指南 D4448号 和 D6771 )和采样准备和处理（指南 D5903 , D6089 , D6517 , D6564/D6564M 和 D6911 ). 1.5 当适当安装和开发时，许多此类设备可用于执行气动缓动测试（实践 D7242/D7242M )定量评估松散地层离散层段的地层导水率。这些段塞试验提供了可靠的导水率测定，可在水质采样完成后进行。 1.6 直接推进水取样仅限于可用设备可穿透的松散地层。在坚硬土壤中，插入取样器时，杆弯曲或组件屈曲可能会导致损坏。在某些地面条件下，贯入可能受到限制，或对取样器或杆件造成损坏，其中一些在 5.7 . 钻井设备，如声波钻井（实践 D6914/D6914M )或旋转钻孔（导向 D6286/D6286M )可用于通过使用典型的直接推动设备难以穿透的地层推进钻孔。有些土层不能及时产水直接用于灌溉- 推送采样。对于不屈服地层，可以进行直接推土取样（指南 D6282/D6282M ). 1.7 也可以使用锥贯入仪设备（指南）使用一次性密封滤网取样器进行直接推水取样 D6067/D6067M ). 1.8 本指南不涉及永久性水取样系统的安装，如实践中介绍的系统 D5092/D5092M . 指南中介绍了用于长期监测的直接推注监测井 D6724/D6724M 和实践 D6725/D6725M . 1.9 单位- 以国际单位制或英寸-磅单位表示的数值[括号内]应单独视为标准值。 每个系统中规定的值可能不是精确的等效值；因此，每个系统应相互独立使用。将两个系统的值合并可能会导致不符合标准。以国际单位制以外的单位报告试验结果不应视为不符合本标准。 1.10 所有观察值和计算值应符合实践中确定的有效数字和舍入准则 D6026 ，除非被本标准取代。 1.11 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。 1.12 本指南提供了有组织的信息收集或一系列选项，并不推荐具体的行动方案。本文件不能取代教育或经验，应与专业判断一起使用。并非本指南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。 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。 1.13 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 直接推动地下水采样和剖面分析是在许多土壤和松散地层中获取离散间隔地下水水质样本的经济方法，无需花费永久监测井安装费用 ( 1- 10 ) . 4. 其中许多装置可通过执行重复采样和测试事件，用于随深度分析地下水质量或污染和/或导水率。DP地下水采样通常用于快速现场表征（实践 D6235 )并作为实现高分辨率场地表征（HRSC）的一种手段 ( 11 , 12 ) . 待取样地层应具有足够的渗透性，以允许在相对较短的时间内填充取样器。可通过匹配取样器筛网长度来隔离待采样区域和/或待测段塞，以获得薄饱和渗透层的离散样本。 使用这些采样和水力测试技术将更详细地描述包含多个含水层的场地。应审查现场条件、采样器设计和数据质量目标，以确定是否开发（指南 D5521/D5521M )筛分地层的厚度是合适的。取样器没有像常规井那样设计用于保留细粒的过滤组件，只有一个开槽滤网或钢丝网覆盖的端口。因此，在含有大量细粒的地层中，获取低浊度样品可能很困难，甚至不可能- 颗粒材料。对于大多数系统，浊度总是很高，因此请参阅指南 D6564/D6564M 如果需要现场过滤样品。离散水采样，结合目标含水层的位置和厚度知识，可以更好地确定薄多含水层中的条件，而不是具有长筛选间隔的监测井，可以相交并允许多个含水层相互通信 ( 4. , 6. , 11- 15 ) . 在不知道目标含水层的位置和厚度的情况下进行DP采样可能会导致对错误含水层进行采样或穿透封闭层。 DP勘探的结果可用于开发概念性现场模型、指导永久性地下水监测井的布置和直接修复工作。这些设备通常在动态工作计划下使用 ( 11 , 16 ) 在一次动员中完成现场特征描述。然而，可以执行多个采样事件来描述随时间变化的条件，或者根据需要改进早期工作。 5.2 针对含水层样本测试区进行准确采样- 与任何调查一样，重要的是分阶段进行调查，以便准确定位地下水采样的目标间隔。 对于允许表面推动取样装置的现场，离散水取样通常与锥体贯入试验（试验方法）一起进行 D6067/D6067M ) ( 4- 6. , 13 , 14 ) 或连续土壤采样（指南 D6282/D6282M )它通常用于绘制含水层的地层图，并划定高渗透带进行采样。或者，电阻率测井或注入测井（实践 D8037/D8037M )可用于在地下水采样或剖面分析活动之前评估地层渗透性和岩性，以指导采样间隔的选择 ( 10 , 15 , 17 ) . 在这种情况下，DP水取样通常在之前的测试孔附近进行。在复杂的沉积环境中 ( 12 ) 薄含水层的连续性可能不同，因此水取样装置可能不会在与配套HPT、圆锥贯入仪或电阻率剖面测深相同的深度处与同一层相交。 5.2.1 当地下存在三氯乙烯（TCE）或苯等挥发性有机污染物（VOC）时，使用膜界面探针（MIP）进行测井（实践 D7352 )可在地下水采样之前进行。 MIP测井确定了许多挥发性有机化合物的显著浓度所在，并可用于指导地下水采样位置、深度和间隔的选择 ( 17 ) . 当地下激光诱导荧光（LIF）中存在石油燃料时（实践 D6187 )或光学成像轮廓仪（OIP） ( 18 ) 可用于确定存在重大石油污染的位置，以帮助指导选择样品位置和深度。 5.3 可以使用多个DP地下水采样器进行段塞试验( D7242/D7242M )确定离散区间的导水率。 应制定筛选间隔，以确保流入和流出装置的地层流量代表自然地层条件。使用简单的惯性泵进行喘振和净化地层通常是足够的。其他开发方法( D5521/D5521M )可根据现场条件和数据质量目标进行建议。 5.4 可以密封水取样室，以保持现场压力，并允许进行压力测量和渗透性测试（实践 D7242/D7242M ) ( 6. , 13 , 19 ) . 在压力下密封样品可能会减少某些有机化合物的可能挥发。 现场比较可用于评估采样设备和方法中的任何系统误差。比较研究可能包括需要对样品加压，或使用真空更快速地从低导水率土壤中提取液体( 8.2.3.1 ( 2. )). 5.5 DP地下水剖面工具 ( 7. , 8. , 10 , 20 , 21 ) 允许研究人员在装置递增推进期间在多个深度采集地下水样本。清洁水通过这些工具的滤网或端口注入，以保持滤网打开，并在推进过程中进行冲洗。必须考虑交叉污染和污染物下拉的问题。 有些工具在地面上或井下都有一个内联压力传感器，用于监测推进过程中向地层注水所需的压力。压力注入测井可用于指导采样渗透带的选择。当同时测量注入流量时，可以计算地层渗透率的估计值。 5.6 如果将密封滤网取样器的离散水采样事件与潜在污染物的实时现场分析相结合，可以减少处理和运输过程中水样的降解。在有限的研究中，研究人员发现，将离散密封筛网采样与现场分析测试相结合，可以提供测试时含水层水质状况的准确数据 ( 4. , 6. ) . 根据测试过程中采取的预防措施，可能需要开发或吹扫的外露滤网取样装置的DP水取样被视为筛选工具。 5.7 在困难的行驶条件下，可能无法穿透至所需深度以确保采样器滤网的密封。如果无法将滤网插入地层中并进行充分密封，则需要按照惯例对水取样事件进行密封 D5092/D5092M 隔离含水层。应与经验丰富的操作员或制造商协商，选择适当的设备和方法，以在相关现场达到所需深度。 如果没有关于地下条件的信息，则初始勘探包括渗透阻力测试，例如测试方法 D6067/D6067M ，电阻率剖面，或使用注入测井系统进行DP测井（实践 D8037/D8037M )为了进行试验，可以选择合适的测试系统。 5.7.1 特定设备配置的典型穿透深度取决于许多变量。其中一些变量是驱动系统、取样器和立管的直径以及材料的阻力。 5.7.2 某些地下条件可能会阻止插入取样器。 在坚硬岩石中不可能穿透，有时在粘土岩和页岩等较软岩石中也不可能穿透。砾石、鹅卵石和巨砾等粗颗粒可能难以穿透或损坏取样器或立管。根据土层的强度和厚度，水泥土区可能难以渗透。如果存在阻止表面DP的地层，则采用旋转或冲击钻井方法（指南 D6286/D6286M )可用于通过阻碍层推进钻孔，以达到测试区域。 5.7.3 驱动系统通常根据测试深度和待穿透材料进行选择。 对于主要使用静态反作用力插入取样器的系统，深度将受到设备反作用力重量或材料锚固稳定性和渗透阻力的限制。还应考虑回拉抽油杆柱的能力。冲击或冲击土壤探测具有减少穿透所需反应重量的优点。通过增加尖端或减阻剂来减少杆摩擦，可以提高粘土中的穿透能力。然而，过度扩孔可能会增加杆屈曲的可能性，并允许不同地下水位的通信。 手持式设备通常用于非常浅的勘探，通常深度小于5米[15英尺]，但在非常软的湖相粘土中已达到约10米[30英尺]的深度。中型驱动系统，例如小型卡车安装的液压推动和冲击驱动器，通常在5到30米[20到100英尺]的深度范围内工作。根据地下条件，较大的DP机器可能能够达到60米[200英尺]。重型静态推锥贯入仪车辆，如20吨卡车，通常在15至45米[50至150英尺]的深度范围内工作，在软土地基条件下也可达到100米[300英尺]的深度范围。 指导 D6286/D6286M 显示了其他钻井设备达到更大深度的深度范围。 注1: 用户和制造商无法就不同土壤类型的深度范围达成一致。用户应咨询有经验的当地生产商和制造商，以确定其特定现场条件的深度能力。 5.8 在单个样本室中组合多个采样事件（分析），而无需净化（实践 D5088 )通常不鼓励。在此应用中，应对滤网或取样室进行吹扫，以确保隔离取样事件。 应通过移除多个体积的流体来进行吹扫，直到新的化学性质稳定，或用已知化学性质的流体冲洗元件。吹扫要求可能取决于取样器中使用的材料和取样器设计（指南 D6634/D6634M ). 可以收集和分析冲洗液样本，以评估来自严重污染覆盖区的污染物携带问题。监测水质参数（pH值、电导率、溶解氧、氧化还原电位等）的稳定性，通常用于记录从采样间隔清洗代表性水的时间（实践 D6771 ). 5.9 应避免通过将DP地下水采样器驱动至地层底部并在滤网暴露的情况下逐渐缩回进行自下而上的剖面分析，以减少深度采样，因为这可能导致交叉污染和不准确的污染物分布信息。段塞测试不应采用自下而上的剖面法，因为在这些条件下，对测试的地层长度控制较差或没有控制。 5.10 在双管使用中设计和部署的滤网通常设计用于双管内，过钻滤网穿过套管可能会损坏取样器滤网，随后暴露的滤网样品将受到交叉污染。 根据制造商说明使用设备。 注2: 本标准产生的结果的质量取决于执行该标准的人员的能力，以及所用设备和设施的适用性。符合执业标准的从业人员 D3740 通常认为能够胜任和客观的测试/采样/检查等。本标准的用户应注意遵守惯例 D3740 本身并不能保证可靠的结果。可靠的结果取决于许多因素；实践 D3740 提供了一种评估其中一些因素的方法。 实践 D3740 是为从事土壤和岩石测试和/或检查的机构开发的。因此，它并不完全适用于执行该现场实践的机构。然而，这种做法的用户应该认识到，实践框架 D3740 适用于评估执行此实践的机构的质量。目前，还没有已知的合格国家机构来检查执行这种做法的机构。

1.1 This guide covers a review of methods for sampling groundwater at discrete points or in increments by insertion of groundwater sampling devices using Direct Push Methods ( D6286/D6286M , see 3.3.2). By directly pushing the sampler, the soil is displaced and helps to form an annular seal above the sampling zone. Direct-push water sampling can be one time, or multiple sampling events. Knowledge of site specific geology and hydrogeologic conditions is necessary to successfully obtain groundwater samples with these devices. 1.2 Direct-push methods of water sampling are used for groundwater quality and geohydrologic studies. Water quality and permeability may vary at different depths below the surface depending on geohydrologic conditions. Incremental sampling or sampling at discrete depths is used to determine the distribution of contaminants and to more completely characterize geohydrologic environments. These explorations are frequently advised in characterization of hazardous and toxic waste sites and for geohydrologic studies. 1.3 This guide covers several types of groundwater samplers; sealed screen samplers, profiling samplers, dual tube sampling systems, and simple exposed screen samplers. In general, sealed screen samplers driven to discrete depth provide the highest quality water samples. Profiling samplers using an exposed screen(s) which are purged between sampling events allow for more rapid sample collection at multiple depths. Simple exposed screen samplers driven to a test zone with no purging prior to sampling may result in more questionable water quality if exposed to upper contaminated zones, and in that case, would be considered screening devices. 1.4 Methods for obtaining groundwater samples for water quality analysis and detection of contaminants are presented. These methods include use of related standards such as; selection of purging and sampling devices (Guide D6452 and D6634/D6634M ), sampling methods (Guide D4448 and D6771 ) and sampling preparation and handling (Guides D5903 , D6089 , D6517 , D6564/D6564M , and D6911 ). 1.5 When appropriately installed and developed many of these devices may be used to perform pneumatic slug testing (Practice D7242/D7242M ) to quantitatively evaluate formation hydraulic conductivity over discrete intervals of unconsolidated formations. These slug tests provide reliable determinations of hydraulic conductivity and can be performed after water quality sampling is completed. 1.6 Direct-push water sampling is limited to unconsolidated formations that can be penetrated with available equipment. In strong soils damage may result during insertion of the sampler from rod bending or assembly buckling. Penetration may be limited, or damage to samplers or rods can occur in certain ground conditions, some of which are discussed in 5.7 . Drilling equipment such as sonic drilling (Practice D6914/D6914M ) or rotary drilling (Guide D6286/D6286M ) can be used to advance holes past formations difficult to penetrate using typical Direct Push equipment. Some soil formations do not yield water in a timely fashion for direct-push sampling. In the case of unyielding formations, direct-push soil sampling can be performed (Guide D6282/D6282M ). 1.7 Direct push water sampling with one-time sealed screen samplers can also be performed using cone penetrometer equipment (Guide D6067/D6067M ). 1.8 This guide does not address installation of permanent water sampling systems such as those presented in Practice D5092/D5092M . Direct-push monitoring wells for long term monitoring are addressed in Guide D6724/D6724M and Practice D6725/D6725M . 1.9 Units— The values stated in either SI units or inch-pound units [presented in brackets] are to be regarded separately as standard. The values stated in each system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in nonconformance with the standard. Reporting of test results in units other than SI shall not be regarded as nonconformance with this standard. 1.10 All observed and calculated values shall conform to the guidelines for significant digits and rounding established in Practice D6026 , unless superseded by this standard. 1.11 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. 1.12 This guide offers an organized collection of information or a series of options and does not recommend a specific course of action. This document cannot replace education or experience and should be used in conjunction with professional judgment. Not all aspects of this guide 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 of this document means only that the document has been approved through the ASTM consensus process. 1.13 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 Direct-push groundwater sampling and profiling are economical methods for obtaining discrete interval groundwater quality samples in many soils and unconsolidated formations without the expense of permanent monitoring well installation ( 1- 10 ) . 4 Many of these devices can be used to profile groundwater quality or contamination and/or hydraulic conductivity with depth by performing repetitive sampling and testing events. DP groundwater sampling is often used in expedited site characterization (Practice D6235 ) and as a means to accomplish high resolution site characterization (HRSC) ( 11 , 12 ) . The formation to be sampled should be sufficiently permeable to allow filling of the sampler in a relatively short time. The zone to be sampled and/or slug tested can be isolated by matching sampler screen length to obtain discrete samples of thin saturated, permeable layers. Use of these sampling and hydraulic testing techniques will result in more detailed characterization of sites containing multiple aquifers. The field conditions, sampler design and data quality objectives should be reviewed to determine if development (Guide D5521/D5521M ) of the screened formation is appropriate. The samplers do not have a filter pack designed to retain fines like conventional wells, but only a slotted screen or wire-mesh covered ports. So, obtaining low turbidity samples may be difficult or even impossible in formations with a significant proportion of fine-grained materials. With most systems turbidity will always be high so consult Guide D6564/D6564M if field filtration of samples is required. Discrete water sampling, combined with knowledge of location and thickness of target aquifers, may better define conditions in thin multiple aquifers than monitoring wells with long screened intervals that can intersect and allow for intercommunication of multiple aquifers ( 4 , 6 , 11- 15 ) . DP sampling performed without knowledge of the location and thickness of target aquifers can result in sampling of the wrong aquifer or penetration through confining beds. Results from DP explorations can be used to develop conceptual site models, guide placement of permanent groundwater monitoring wells, and direct remediation efforts. These devices are often used under dynamic work plans ( 11 , 16 ) to complete site characterizations in a single mobilization. However, multiple sampling events can be performed to depict conditions over time or refine earlier work if needed. 5.2 Targeting Aquifer Sample Test Zones for Accurate Sampling— As with any investigation it is important to phase the investigation such that target intervals for groundwater sampling are accurately located. For sites that allow surface push of the sampling device, discrete water sampling is often performed in conjunction with the cone penetration test (Test Method D6067/D6067M ) ( 4- 6 , 13 , 14 ) or continuous soil sampling (Guide D6282/D6282M ) which is often used for stratigraphic mapping of aquifers and to delineate high-permeability zones for sampling. Alternately, resistivity logging, or injection logging (Practice D8037/D8037M ) may be used to assess formation permeability and lithology prior to the groundwater sampling or profiling activities to guide selection of sampling intervals ( 10 , 15 , 17 ) . In such cases, DP water sampling is normally performed close to previous test holes. In complex depositional environments ( 12 ) , thin aquifers may vary in continuity such that water sampling devices may not intersect the same layer at equivalent depths as companion HPT, cone penetrometer, or electrical resistivity profiling soundings. 5.2.1 When volatile organic contaminants (VOC) such as trichloroethylene (TCE) or benzene are present in the subsurface, logging with the membrane interface probe (MIP) (Practice D7352 ) may be performed prior to groundwater sampling. MIP logs identify where significant concentrations of many VOCs are present and may be used to guide selection of groundwater sampling locations, depths and intervals ( 17 ) . When petroleum fuels are present in the subsurface laser induced fluorescence (LIF) (Practice D6187 ) or the Optical Imaging Profiler (OIP) ( 18 ) may be used to identify where significant petroleum contamination is present to assist in guiding selection of sample locations and depths. 5.3 Slug tests can be performed with several of the DP groundwater samplers ( D7242/D7242M ) to determine hydraulic conductivity over discrete intervals. Development of the screened interval should be conducted to assure that formation flow into and out of the device is representative of natural formation conditions. Development with a simple inertial pump to surge and purge the formation is often adequate. Other methods for development ( D5521/D5521M ) may be advised depending on field conditions and data quality objectives. 5.4 Water sampling chambers may be sealed to maintain in situ pressures and to allow for pressure measurements and permeability testing (Practice D7242/D7242M ) ( 6 , 13 , 19 ) . Sealing of samples under pressure may reduce the possible volatilization of some organic compounds. Field comparisons may be used to evaluate any systematic errors in sampling equipments and methods. Comparison studies may include the need for pressurizing samples, or the use of vacuum to extract fluids more rapidly from low hydraulic conductivity soils ( 8.2.3.1 ( 2 )). 5.5 DP groundwater profiling tools ( 7 , 8 , 10 , 20 , 21 ) allow the investigator to sample groundwater at multiple depths during incremental advancement of the device. Clean water is injected through the screen(s) or port(s) of these tools to keep the screens open and rinsed as advancement proceeds. Concerns for cross contamination and contaminant drag down must be considered. Some tools have an inline pressure transducer either above grade or down hole to monitor pressure required to inject water into the formation during advancement. The pressure injection log may be used to guide selection of permeable zones for sampling. When the injection flow rate is also measured, estimates of formation permeability may be calculated. 5.6 Degradation of water samples during handling and transport can be reduced if discrete water sampling events with sealed screen samplers are combined with real time field analysis of potential contaminants. In limited studies, researchers have found that the combination of discrete sealed screen sampling with onsite field analytical testing provide accurate data of aquifer water quality conditions at the time of testing ( 4 , 6 ) . DP water sampling with exposed screen sampling devices, which may require development or purging, are considered as screening tools depending on precautions that are taken during testing. 5.7 In difficult driving conditions, penetrating to the desired depth to make sure of sealing of the sampler screen may not be possible. If the screen cannot be inserted into the formation with an adequate seal, the water-sampling event would require sealing in accordance with Practice D5092/D5092M to isolate the aquifer. Selection of the appropriate equipment and methods to reach required depth at the site of concern should be made in consultation with experienced operators or manufacturers. If there is no information as to the subsurface conditions, initial explorations consisting of penetration-resistance tests, such as Test Method D6067/D6067M , resistivity profiling, or DP logging with the injection logging system (Practice D8037/D8037M ) to perform trials can be performed to select the appropriate testing system. 5.7.1 Typical penetration depths for a specific equipment configuration depend on many variables. Some of the variables are the driving system, the diameter of the sampler and riser pipes, and the resistance of the materials. 5.7.2 Certain subsurface conditions may prevent sampler insertion. Penetration is not possible in hard rock and sometimes not possible in softer rocks such as claystones and shales. Coarse particles such as gravels, cobbles, and boulders may be difficult to penetrate or cause damage to the sampler or riser pipes. Cemented soil zones may be difficult to penetrate depending on the strength and thickness of the layers. If layers are present that prevent DP from the surface, then rotary or percussion drilling methods (Guide D6286/D6286M ) can be employed to advance a boring through impeding layers to reach testing zones. 5.7.3 Driving systems are generally selected based on testing depths and the materials to be penetrated. For systems using primarily static reaction force to insert the sampler, depth will be limited by the reaction weight of the equipment or anchoring stability and penetration resistance of the material. The ability to pull back the rod string is also a consideration. Impact or percussion soil probing has an advantage of reducing the reaction weight required for penetration. Penetration capability in clays may be increased by reducing rod friction by enlarging tips or friction reducers. However, over reaming of the hole may increase the possibility of rod buckling and may allow for communication of differing groundwater tables. Hand-held equipment is generally used on very shallow explorations, typically less than 5 m [15 ft] depth, but depths on the order of 10 m [30 ft] have been reached in very soft lacustrine clays. Intermediate size driving systems, such as small truck-mounted hydraulic-powered push and impact drivers, typically work within depth ranges from 5 to 30 m [20 to 100 ft]. Larger DP machines may be capable of reaching 60 m [200 ft] depending on subsurface conditions. Heavy static-push cone penetrometer vehicles, such as 20 ton trucks, typically work within depth ranges from 15 to 45 m [50 to 150 ft], and also reach depth ranges on the order of 100 m [300 ft] in soft ground conditions. Guide D6286/D6286M shows depth ranges of other drilling equipment to attain greater depths. Note 1: Users and manufacturers cannot agree on depth ranges for different soil types. Users should consult with experienced local producers and manufacturers to determine depth capability for their specific site conditions. 5.8 Combining multiple-sampling events in a single-sample chamber (profiling) without decontamination (Practice D5088 ) is generally discouraged. In this application, purging of the screen or sampling chamber should be performed to make sure of isolation of the sampling event. Purging should be performed by removing several volumes of fluid until new chemical properties have been stabilized or elements are flushed with fluid of known chemistry. Purging requirements may depend upon the materials used in the sampler and the sampler design (Guide D6634/D6634M ). Rinsate samples may be collected and analyzed to assess concerns with carryover of contaminants from overlying zones that are heavily contaminated. Monitoring water quality parameters (pH, specific conductance, dissolved oxygen, oxidation-reduction potential, etc.) to stability is often used to document when representative water is being purged from a sampling interval (Practice D6771 ). 5.9 Bottom-up profiling by driving a DP groundwater sampler to the base of the formation and retracting incrementally, while the screen is exposed, for sampling at decreasing depths should be avoided as this may lead to cross contamination and inaccurate contaminant distribution information. Slug tests should not be performed by bottom-up profiling as there is poor or no control on the length of formation being tested under these conditions. 5.10 Screens designed and deployed in dual tube use are generally designed for use inside the dual tubing and overdriving the screen past the casing can damage the sampler screen and subsequent exposed screen samples would be subject to cross contamination. Use equipment according to manufactures instructions. Note 2: The quality of the result produced by this standard is dependent on the competence of the personnel performing it, and the suitability of the equipment and facilities used. Practitioners that meet the criteria of Practice D3740 are generally considered capable of competent and objective testing/sampling/inspection/etc. Users of this standard are cautioned that compliance with Practice D3740 does not in itself assure reliable results. Reliable results depend on many factors; Practice D3740 provides a means of evaluating some of those factors. Practice D3740 was developed for agencies engaged in the testing and/or inspection of soils and rock. As such, it is not totally applicable to agencies performing this field practice. However, users of this practice should recognize that the framework of Practice D3740 is appropriate for evaluating the quality of an agency performing this practice. Currently there is no known qualifying national authority that inspects agencies that perform this practice.