1、Designation: D6452 99 (Reapproved 2012)1D6452 18Standard Guide forPurging Methods for Wells Used for Groundwater GroundWater Quality Investigations1This standard is issued under the fixed designation D6452; the number immediately following the designation indicates the year oforiginal adoption or, i
2、n the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1 NOTEEditorial changes were made throughout in July 2012.1. Scope Scope*1.1 This guide covers
3、 methods for purging wells used for groundwater ground water quality investigations and monitoringprograms. These methods could be used for other types of programs but are not addressed in this guide.1.2 This guide applies only to wells sampled at the wellhead.1.3 This standard describes seven metho
4、ds (A-G) for the selection of purging methods. Method AFixed Volume Purging,Method BPurging Based on Stabilization of Indicator Parameters, Method CPurging Based on Stabilization of TargetAnalytes, Method DPurging Based on Fixed Volume Combined with Indicator Parameter Stabilization, Method ELowFlow
5、/Low Volume (Minimal Drawdown) Purging, Method FWell Evacuation Purging, and Method GUse of Packers inPurging.Method AFixed Volume Purging,Method BPurging Based on Stabilization of Indicator Parameters,Method CPurging Based on Stabilization of Target Analytes,Method DPurging Based on Fixed Volume Co
6、mbined with Indicator Parameter Stabilization,Method ELow Flow/Low Volume (Minimal Drawdown) Purging,Method FWell Evacuation Purging, andMethod GUse of Packers in Purging.1.4 This guide offers an organized collection of information or a series of options and does not recommend a specific courseof ac
7、tion. 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 replacethe standard of care by which the adequacy of a give
8、n professional service must be judged, nor should this documente be appliedwithout consideration of a projects many unique aspects. The word “Standard” in the title of this guide means only that thedocument has been approved through the ASTM consensus process.1.4 This guide offers an organized colle
9、ction of information or a series of options and does not recommend a specific courseof 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
10、 not intended to represent or replacethe standard of care by which the adequacy of a given professional service must be judged, nor should this document be appliedwithout consideration of a projects many unique aspects. The word “Standard” in the title of this guide means only that thedocument has b
11、een approved through the ASTM consensus process.1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety safety, health, and healthenvironmental practices and to det
12、ermine theapplicability of regulatory limitations prior to use.1.6 This international standard was developed in accordance with internationally recognized principles on standardizationestablished in the Decision on Principles for the Development of International Standards, Guides and Recommendations
13、 issuedby the World Trade Organization Technical Barriers to Trade (TBT) Committee.1 This guide is under the jurisdiction of ASTM Committee D18 on Soil and Rock and is the direct responsibility of Subcommittee D18.21 on Groundwater and VadoseZone Investigations.Current edition approved July 1, 2012D
14、ec. 1, 2018. Published November 2012December 2018. Originally approved in 1999. Last previous edition approved in 20052012as D645299(2005).D645299(2012)1. DOI: 10.1520/D6452-99R12E01.10.1520/D6452-18.This document is not an ASTM standard and is intended only to provide the user of an ASTM standard a
15、n indication of what changes have been made to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is t
16、o be considered the official document.*A Summary of Changes section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States12. Referenced Documents2.1 ASTM Standards:2D653 Terminology Relating to Soil, Rock,
17、 and Contained FluidsD4750 Test Method for Determining Subsurface Liquid Levels in a Borehole or Monitoring Well (Observation Well)(Withdrawn 2010)3D5088 Practice for Decontamination of Field Equipment Used at Waste SitesD5092D5092/D5092M Practice for Design and Installation of Groundwater Monitorin
18、g WellsD5521D5521/D5521M Guide for Development of Groundwater Monitoring Wells in Granular AquifersD6089 Guide for Documenting a Groundwater Sampling EventD6771 Practice for Low-Flow Purging and Sampling for Wells and Devices Used for Ground-Water Quality Investigations3. Terminology3.1 Definitions:
19、3.1.1 For definitions of common technical terms in this standard, refer to Terminology D653.3.2 Definitions:Definitions of Terms Specific to This Standard:3.1.1 For definitions of common technical terms in this standard, refer to Terminology D653.3.1.2 casing volumethe quantity of water contained in
20、 the casing above the screen or open borehole.3.2.1 fixed volume purgingpurging, nin ground water sampling, removing a specified number of well volumes to achievepurging.3.2.2 flow-through cell (purging)(purging), nin ground water sampling, a vessel that allows purge water to pass over sensorsfor co
21、ntinuous measurement of indicator parameters.3.1.5 flushingsee purging.3.2.3 grab sampling devicedevice, nin ground water sampling, a bailer or similar device that removes an aliquot of waterfrom the well with each insertion and removal from the well.3.1.7 indicator parameters (purging)those physica
22、l or chemical properties, or both, used as a correlative measure to determinewhen water to be sampled reflects ambient groundwater chemistry.3.2.4 low yield wellwell, nin ground water sampling, a well that does not produce sufficient water such that the objectivesof purging and sampling cannot be ac
23、hieved without first removing most or nearly all water from the well.3.2.5 packer (purging)(purging), nan expandable device used to physicallyin ground water samplingin monitoring wells,isolate one or more zones in a well.a transient or dedicated device placed in a well that isolates or seals a port
24、ion of the well, wellannulus, or borehole at a specific level.3.1.10 purge volumethe quantity of water removed from the well to accomplish the objectives of purging.3.2.6 purgingpurging, nin ground water sampling, the practice of removing stagnant (standing) water from a well prior tosampling.3.1.12
25、 purging ratethe rate at which water is removed from a well or sampling point during purging.3.1.13 recovery rate (purging)the rate at which the water level in a well returns to equilibrium with the hydraulic conditionsof the formation after the removal of water.3.2.7 stabilizationstabilization, nin
26、 ground water sampling, a decrease in the change between measured values to conditionoccurring when changes in indicator parameters and operational parameter values are maintained within a specified range orpercentage of the measured value over a selected number of consecutive readings and it appear
27、s the readings will continue toremain within that specified range during subsequent readings.3.2.7.1 DiscussionThe interval between readings is chosen for either a given time period or volume of water removed.3.2.8 stagnant waterwater, nin ground water sampling, the water contained in a well above t
28、he screened interval orformation inflows (for uncased wells) between sampling events that may have interacted with materials or the headspace in thewell, or both, and thus may be different from ambient groundwater ground water conditions.3.2.8.1 Discussion2 For referencedASTM standards, visit theAST
29、M website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.D6452 182Water within the screened area or formation inflows are generally reflective of the ambient grou
30、nd water conditions.3.2.9 target analytewell intake, (purging)nin ground water sampling,a chemical constituent or physical characteristic to beanalyzed for the purpose of fulfilling program objectives. the area in a screened well or open bore well where formation waterenters.3.2.10 well volumevolume
31、, nin ground water sampling, the quantity of water contained in the casing and the screen for ascreened well, or in the open borehole and casing in an unscreened well. For an unscreened well, this volume may also be referredto as a borehole volume.3.2.10.1 DiscussionRegulations or guidance documents
32、 may contain other definitions of well volume and should be consulted.4. Significance and Use4.1 Wells used in groundwater quality investigations or monitoring programs are generally purged prior to sampling (Note 1).Purging is done to minimize the bias associated with stagnant water in the well, wh
33、ich generally does for a variety of reasons andthe purging method may depend on the hydrogeologic setting, condition of the well, or the contaminants of interest and wellproduction rates. well hydrological conditions, condition of the well, or the contaminants of interest, and well production rates.
34、This guide presents an approach for selecting an appropriate purging method if purging is to be performed., Water above thescreened interval or open borehole may not accurately reflect ambient groundwater chemistry (ground water chemistry.Note 2).NOTE 1Some sampling methods, such as passive sampling
35、, do not require the practice of purging prior to sample collection (1,2).3NOTE 2This guide does not address the practice of post-sample purging (purging again after sampling is completed), which is intended for purposesother than the minimization of bias associated with stagnant water in the well.4
36、.2 There are various methods for purging. Each purging method may have a different volume of influence within the aquiferor screened interval. Therefore, a sample collected after purging by any one method is not necessarily equivalent to samplescollected after purging by the other methods. The selec
37、tion of the appropriate method will be dependent on a number of severalfactors, which should be defined during the development of the sampling and analysis plan. This guide describes the methodsavailable and defines the circumstances under which each method may be appropriate.5. Criteria and Conside
38、rations for Selecting an Appropriate Purging Method5.1 Regulations or Other GuidanceDetermine if any Statelocal or Federalnational regulations or guidance exist pertaining topurging monitoring wells. Purging may be addressed as part of a broader regulation or guidance document on field investigation
39、sor groundwater ground water monitoring.5.2 Historical DataReview of historical data can provide the user with information about the chemical and physical behaviorof the groundwater ground water at the sampling point during purging and details regarding past purging practices.5.3 Well Design (Practi
40、ce D5092D5092/D5092M)The design of the well mustshould be considered to selectwhen selectingan appropriate purging method. Refer to Section 7 for how specific well design details affect the selection of purging methods.5.4 Well Development (Guide D5521D5521/D5521M)Well development is part of the wel
41、l construction or maintenanceprocess and not part of a purging and sampling event. Information on well development can be found in Guide D5521D5521/D5521M.NOTE 2Improper or inadequate well development can affect the suitability of the well for use in the sampling program.5.5 Hydraulics of the WellSe
42、lection of a purging method should include an assessment of well-specific hydraulic conditions,which are directly related to formation transmissivity and well design, construction, development, and maintenance. Well andformation hydraulics (the 3-dimensional distribution of head) influence the rate
43、at which water flows through or enters the wellintake under laminar flow conditions. Purging strategies are commonly categorized as being suitable for high-yield wells orlow-yield wells.NOTE 3Wells in Karst areas present challenges, such as when wells are linked into subsidiary conduit systems. In s
44、ome cases, the purging andsampling may not reliably characterize the aquifer (3), (4).5.6 Purge Water ManagementManage purge water in accordance with the site-specific waste management provisions of thesampling and analysis plan. It may be preferable to select a purging method to minimize the purge
45、volume, especially when purgewater must be containerized. (See Note 1.)3 The last approved version of this historical standard is referenced on www.astm.org.3 The boldface numbers given in parentheses refer to a list of references at the end of the text.D6452 1835.7 Physical Condition of the WellsTh
46、e physical condition of a well may affect the purging method by limiting the choice ofequipment. For example, physical aberrations of the sampling point such as a cracked casing or siltation could preclude the useof certain purging devices.5.8 Subsurface GeochemistryKnowledge of the subsurface geoch
47、emistry can be useful in selecting a purge method that willbest achieve the goal of removing stagnant water. It can also be useful in distinguishing between water that is non-representativeof the formation water. Water within the screened or intake area is generally representative of the ambient for
48、mation water andstagnant water during the purging process. Chemical chemistry. In other cases, the chemical and biological interaction betweenformation water and the solid-phase materials in the aquifer, bacteria, or the well materials can modify the chemistry of waterstanding in the well or in the
49、vicinity of the near the well. Dissolved gases can be transported into or out of the screened or openinterval and added to or removed from the groundwater ground water across the free surface of the water in the well. Obtainingconsistent representative samples may require that the well be profiled to identify the source(s) of formation water or contaminantsflowing into the well, particularly in karsts systems (3) and repeating the purging procedures for every sampling episode.5.9 Hydrogeologic SettingOptimizing purgi
