ASTM D6452-18(2023)
(Guide)Standard Guide for Purging Methods for Wells Used for Ground Water Quality Investigations
Standard Guide for Purging Methods for Wells Used for Ground Water Quality Investigations
SIGNIFICANCE AND USE
4.1 Purging is done for a variety of reasons and the purging method may depend on the hydrogeologic setting, condition of the well, or the contaminants of interest and well production rates. well hydrological conditions, condition of the well, or the contaminants of interest, and well production rates. This guide presents an approach for selecting an appropriate purging method if purging is to be performed., Water above the screened interval or open borehole may not accurately reflect ambient ground water chemistry.
Note 1: Some sampling methods, such as passive sampling, do not require the practice of purging prior to sample collection (1,2).3
4.2 There are various methods for purging. Each purging method may have a different volume of influence within the aquifer or screened interval. Therefore, a sample collected after purging by any one method is not necessarily equivalent to samples collected after purging by the other methods. The selection of the appropriate method will be dependent on several factors, which should be defined during the development of the sampling and analysis plan. This guide describes the methods available and defines the circumstances under which each method may be appropriate.
SCOPE
1.1 This guide covers methods for purging wells used for ground water quality investigations and monitoring programs. 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 methods (A-G) for the selection of purging methods.
Method A—Fixed Volume Purging,
Method B—Purging Based on Stabilization of Indicator Parameters,
Method C—Purging Based on Stabilization of Target Analytes,
Method D—Purging Based on Fixed Volume Combined with Indicator Parameter Stabilization,
Method E—Low Flow/Low Volume (Minimal Drawdown) Purging,
Method F—Well Evacuation Purging, and
Method G—Use 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 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 guide means only that the document has been 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 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.
General Information
Relations
Standards Content (Sample)
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.
Designation: D6452 − 18 (Reapproved 2023)
Standard Guide for
Purging Methods for Wells Used for Ground Water Quality
Investigations
This standard is issued under the fixed designation D6452; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope* priate safety, health, and environmental practices and deter-
mine the applicability of regulatory limitations prior to use.
1.1 This guide covers methods for purging wells used for
1.6 This international standard was developed in accor-
ground water quality investigations and monitoring programs.
dance with internationally recognized principles on standard-
These methods could be used for other types of programs but
ization established in the Decision on Principles for the
are not addressed in this guide.
Development of International Standards, Guides and Recom-
1.2 This guide applies only to wells sampled at the well-
mendations issued by the World Trade Organization Technical
head.
Barriers to Trade (TBT) Committee.
1.3 This standard describes seven methods (A-G) for the
selection of purging methods.
2. Referenced Documents
Method A—Fixed Volume Purging,
2.1 ASTM Standards:
Method B—Purging Based on Stabilization of Indicator
D653 Terminology Relating to Soil, Rock, and Contained
Parameters,
Fluids
Method C—Purging Based on Stabilization of Target
D5088 Practice for Decontamination of Field Equipment
Analytes,
Used at Waste Sites
Method D—Purging Based on Fixed Volume Combined
D5092/D5092M Practice for Design and Installation of
with Indicator Parameter Stabilization,
Groundwater Monitoring Wells
Method E—Low Flow/Low Volume (Minimal Drawdown)
D5521/D5521M Guide for Development of Groundwater
Purging,
Monitoring Wells in Granular Aquifers
Method F—Well Evacuation Purging, and
D6089 Guide for Documenting a Groundwater Sampling
Method G—Use of Packers in Purging.
Event
1.4 This guide offers an organized collection of information
D6771 Practice for Low-Flow Purging and Sampling Used
or a series of options and does not recommend a specific
for Groundwater Monitoring
course of action. This document cannot replace education or
experience and should be used in conjunction with professional
3. Terminology
judgment. Not all aspects of this guide may be applicable in all
3.1 Definitions:
circumstances. This ASTM standard is not intended to repre-
3.1.1 For definitions of common technical terms in this
sent or replace the standard of care by which the adequacy of
standard, refer to Terminology D653.
a given professional service must be judged, nor should this
document be applied without consideration of a project’s many
3.2 Definitions of Terms Specific to This Standard:
unique aspects. The word “Standard” in the title of this guide
3.2.1 fixed volume purging, n—in ground water sampling,
means only that the document has been approved through the
removing a specified number of well volumes to achieve
ASTM consensus process.
purging.
1.5 This standard does not purport to address all of the
3.2.2 flow-through cell (purging), n—in ground water
safety concerns, if any, associated with its use. It is the
sampling, a vessel that allows purge water to pass over sensors
responsibility of the user of this standard to establish appro-
for continuous measurement of indicator parameters.
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
Vadose Zone Investigations. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved Nov. 1, 2023. Published November 2023. Originally contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
approved in 1999. Last previous edition approved in 2018 as D6452–18. DOI: Standards volume information, refer to the standard’s Document Summary page on
10.1520/D6452-18R23. the ASTM website.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D6452 − 18 (2023)
require the practice of purging prior to sample collection (1,2).
3.2.3 grab sampling device, n—in ground water sampling, a
bailer or similar device that removes an aliquot of water from
4.2 There are various methods for purging. Each purging
the well with each insertion and removal from the well.
method may have a different volume of influence within the
aquifer or screened interval. Therefore, a sample collected after
3.2.4 low yield well, n—in ground water sampling, a well
purging by any one method is not necessarily equivalent to
that does not produce sufficient water such that the objectives
samples collected after purging by the other methods. The
of purging and sampling cannot be achieved without first
selection of the appropriate method will be dependent on
removing most or nearly all water from the well.
several factors, which should be defined during the develop-
3.2.5 packer (purging), n—in ground water sampling—in
ment of the sampling and analysis plan. This guide describes
monitoring wells, a transient or dedicated device placed in a
the methods available and defines the circumstances under
well that isolates or seals a portion of the well, well annulus, or
which each method may be appropriate.
borehole at a specific level.
5. Criteria and Considerations for Selecting an
3.2.6 purging, n—in ground water sampling, the practice of
Appropriate Purging Method
removing water from a well prior to sampling.
5.1 Regulations or Other Guidance—Determine if any local
3.2.7 stabilization, n—in ground water sampling, a condi-
or national regulations or guidance exist pertaining to purging
tion occurring when changes in indicator parameters and
monitoring wells. Purging may be addressed as part of a
operational parameter values are maintained within a specified
broader regulation or guidance document on field investiga-
range over a selected number of consecutive readings and it
tions or ground water monitoring.
appears the readings will continue to remain within that
5.2 Historical Data—Review of historical data can provide
specified range during subsequent readings.
the user with information about the chemical and physical
3.2.7.1 Discussion—The interval between readings is cho-
behavior of the ground water at the sampling point during
sen for either a given time period or volume of water removed.
purging and details regarding past purging practices.
3.2.8 stagnant water, n—in ground water sampling, the
5.3 Well Design (Practice D5092/D5092M)—The design of
water contained in a well above the screened interval or
the well should be considered when selecting an appropriate
formation inflows (for uncased wells) between sampling events purging method. Refer to Section 7 for how specific well
that may have interacted with materials or the headspace in the design details affect the selection of purging methods.
well, or both, and thus may be different from ambient ground
5.4 Well Development (Guide D5521/D5521M)—Well de-
water conditions.
velopment is part of the well construction or maintenance
3.2.8.1 Discussion—Water within the screened area or for-
process and not part of a purging and sampling event. Infor-
mation inflows are generally reflective of the ambient ground
mation on well development can be found in Guide D5521/
water conditions.
D5521M.
3.2.9 well intake, n—in ground water sampling, the area in
NOTE 2—Improper or inadequate well development can affect the
suitability of the well for use in the sampling program.
a screened well or open bore well where formation water
enters.
5.5 Hydraulics of the Well—Selection of a purging method
should include an assessment of well-specific hydraulic
3.2.10 well volume, n—in ground water sampling, the quan-
conditions, which are directly related to formation transmis-
tity of water contained in the casing and the screen for a
sivity and well design, construction, development, and main-
screened well, or in the open borehole and casing in an
tenance. Well and formation hydraulics (the 3-dimensional
unscreened well. For an unscreened well, this volume may also
distribution of head) influence the rate at which water flows
be referred to as a borehole volume.
through or enters the well intake under laminar flow condi-
3.2.10.1 Discussion—Regulations or guidance documents
tions. Purging strategies are commonly categorized as being
may contain other definitions of well volume and should be
suitable for high-yield wells or low-yield wells.
consulted.
NOTE 3—Wells in Karst areas present challenges, such as when wells
are linked into subsidiary conduit systems. In some cases, the purging and
4. Significance and Use
sampling may not reliably characterize the aquifer (3), (4).
4.1 Purging is done for a variety of reasons and the purging
5.6 Purge Water Management—Manage purge water in
method may depend on the hydrogeologic setting, condition of
accordance with the site-specific waste management provisions
the well, or the contaminants of interest and well production
of the sampling and analysis plan. It may be preferable to select
rates. well hydrological conditions, condition of the well, or the
a purging method to minimize the purge volume, especially
contaminants of interest, and well production rates. This guide when purge water must be containerized. (See Note 1.)
presents an approach for selecting an appropriate purging
5.7 Physical Condition of the Wells—The physical condition
method if purging is to be performed., Water above the
of a well may affect the purging method by limiting the choice
screened interval or open borehole may not accurately reflect
ambient ground water chemistry.
The boldface numbers given in parentheses refer to a list of references at the
NOTE 1—Some sampling methods, such as passive sampling, do not end of the text.
D6452 − 18 (2023)
of equipment. For example, physical aberrations of the sam- 7.1.4.1 May increase the cost associated with management
pling point such as a cracked casing or siltation could preclude of purge water.
the use of certain purging devices. 7.1.4.2 Not practical for use in low yield wells.
7.1.4.3 Sometimes the number of well volumes is expressed
5.8 Subsurface Geochemistry—Knowledge of the subsur-
as a range (for example, 3 to 5 volumes) making actual purge
face geochemistry can be useful in selecting a purge method
volume open to interpretation and potentially variable between
that will achieve the goal of removing water that is non-
sampling events.
representative of the formation water. Water within the
7.1.4.4 There are no well-specific indicator parameter or
screened or intake area is generally representative of the
target analyte data to determine when the well has been
ambient formation water chemistry. In other cases, the chemi-
adequately purged.
cal and biological interaction between formation water and the
7.1.4.5 The determination of an appropriate purging device,
solid-phase materials in the aquifer, bacteria, or the well
intake location, and rate of water removal are prerequisite to
materials can modify the chemistry of water standing in the
the effective use of this method.
well or near the well. Dissolved gases can be transported into
or out of the screened or open interval and added to or removed 7.2 Method B—Purging Based on Stabilization of Indicator
from the ground water across the free surface of the water in Parameters:
the well. Obtaining consistent representative samples may
7.2.1 Method Description—In this method, field measure-
require that the well be profiled to identify the source(s) of
ments of selected parameters are taken to indicate when the
formation water or contaminants flowing into the well, particu-
well is sufficiently purged. The indicator parameters to be
larly in karsts systems (3) and repeating the purging procedures measured and frequency of measurements should be specified
for every sampling episode.
in the sampling and analysis plan. The most commonly
measured parameters include (but are not limited to) pH,
5.9 Hydrogeologic Setting—Optimizing purging rates re-
specific conductance, turbidity, temperature, dissolved oxygen,
quires consideration of the hydrogeologic characteristics that
and oxidation-reduction potential. The parameters should be
control the direction and rate of water movement and the
selected based on knowledge of water chemistry and analytes
transport of dissolved and colloidal material. Constituents or
of interest, or regulatory requirements, or both. The frequency
concentrations of constituents not characteristic of the forma-
of measurement should be based on purging rate. The accept-
tion water chemistry at the well screen may be transported
able variation of parameter values to define stabilization and
from distant areas to the well by induced flow or reversal of
the number of consecutive stable readings within the pre-
flow direction when purging rates are higher than optimal or
scribed variation for each indicator parameter should be
when purging times are longer than optimal.
defined in the sampling and analysis plan (5, 6). Once
6. Equipment Used for Purging
stabilization has been reached, purging is complete regardless
of the volume of water removed (D6771).
6.1 A variety of devices are appropriate for purging wells.
7.2.2 Applicability—This method can be used in wells
Consideration of the factors in Section 5 may also be useful in
where sufficient yield can be sustained to reliably measure field
selecting purging devices.
indicator parameter concentrations.
6.2 The purging methods described herein require water
7.2.3 Advantages:
level measurements. Some of the purging methods will require
7.2.3.1 Can be performed using a variety of grab sampling
the measurement of indicator parameters. When pumping
and pumping devices.
devices are used for purging, it is preferable to use a flow
7.2.3.2 May result in a lower total purge volume.
through cell for optimal measurement of indicator parameters.
7.2.3.3 Provides well-specific chemical data to determine
when the well has been adequately purged.
7. Purging Methods
7.2.4 Limitations.
7.1 Method A—Fixed Volume Purging:
7.2.4.1 Requires the use and calibration of field parameter
7.1.1 Method Description—This method involves the re-
measurement instrumentation.
moval of a s
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