ASTM D6564-00(2012)e1
(Guide)Standard Guide for Field Filtration of Groundwater Samples
Standard Guide for Field Filtration of Groundwater Samples
SIGNIFICANCE AND USE
4.1 A properly designed, installed and developed groundwater monitoring well, constructed in accordance with Practice D5092, should facilitate collection of samples of groundwater that can be analyzed to determine both the physical and chemical properties of that sample. Samples collected from these wells that require analysis for dissolved constituents should be filtered in the field prior to chemical preservation and shipment to the laboratory for analysis.
SCOPE
1.1 This guide covers methods for field filtration of groundwater samples collected from groundwater monitoring wells, excluding samples that contain non-aqueous phase liquids (either Dense Non-Aqueous Phase Liquids (DNAPLs) or Light Non-Aqueous Phase Liquids (LNAPLs)). Methods of field filtration described herein could also be applied to samples collected from wells used for other purposes. Laboratory filtration methods are not described in this guide.
1.2 This guide provides procedures available for field filtration of groundwater samples. The need for sample filtration for specific analytes should be defined prior to the sampling event and documented in the site-specific sampling and analysis plan in accordance with Guide D5903. The decision should be made on a parameter-specific basis with consideration of the data quality objectives of the sampling program, any applicable regulatory agency guidelines, and analytical method requirements.
1.3 This guide offers an organized collection of information or a series of options and does not recommend a specific course of action. This guide 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 guide 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 guide be applied without consideration of the many unique aspects of a project. The word “Standard” in the title of this guide means only that the guide has been approved through the ASTM consensus process.
1.4 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 and health practices and determine the applicability of regulatory limitations prior to use.
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NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
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Designation: D6564 − 00 (Reapproved 2012)
Standard Guide for
Field Filtration of Groundwater Samples
This standard is issued under the fixed designation D6564; 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.
ε NOTE—Editorial changes were made throughout in May 2012.
1. Scope 2. Referenced Documents
1.1 This guide covers methods for field filtration of ground-
2.1 ASTM Standards:
water samples collected from groundwater monitoring wells, D653 Terminology Relating to Soil, Rock, and Contained
excluding samples that contain non-aqueous phase liquids
Fluids
(either Dense Non-Aqueous Phase Liquids (DNAPLs) or Light D5088 Practice for Decontamination of Field Equipment
Non-Aqueous Phase Liquids (LNAPLs)). Methods of field
Used at Waste Sites
filtration described herein could also be applied to samples D5092 Practice for Design and Installation of Groundwater
collected from wells used for other purposes. Laboratory
Monitoring Wells
filtration methods are not described in this guide. D5903 Guide for Planning and Preparing for a Groundwater
Sampling Event
1.2 This guide provides procedures available for field filtra-
D6089 Guide for Documenting a Groundwater Sampling
tion of groundwater samples.The need for sample filtration for
Event
specific analytes should be defined prior to the sampling event
F740 Definitions ofTerms Relating to Filtration (Withdrawn
and documented in the site-specific sampling and analysis plan
2002)
inaccordancewithGuideD5903.Thedecisionshouldbemade
on a parameter-specific basis with consideration of the data
3. Terminology
quality objectives of the sampling program, any applicable
regulatory agency guidelines, and analytical method require- 3.1 Definitions: For definitions of common technical terms
ments.
in this standard, refer to Terminology D653.
1.3 This guide offers an organized collection of information 3.2 Definitions of Terms Specific to This Standard:
oraseriesofoptionsanddoesnotrecommendaspecificcourse
3.2.1 filter, v—to pass a fluid containing particles through a
of action. This guide cannot replace education or experience
filter medium whereby particles are separated from the fluid.
and should be used in conjunction with professional judgment.
F740
Not all aspects of this guide may be applicable in all circum-
3.2.2 filter, n—a device for carrying out filtration which
stances. This guide is not intended to represent or replace the
consists of the combination of the filter medium and suitable
standard of care by which the adequacy of a given professional
hardware for constraining and supporting it in the path of the
service must be judged, nor should this guide be applied
fluid. F740
without consideration of the many unique aspects of a project.
3.2.3 filter medium—the permeable material used for a filter
The word “Standard” in the title of this guide means only that
that separates particles from a fluid passing through it. F740
the guide has been approved through the ASTM consensus
3.2.4 filter preconditioning—theprocessofpreparingafilter
process.
medium for filtration
1.4 This standard does not purport to address all of the
3.2.5 filter system—the combination of one or more filter
safety concerns, if any, associated with its use. It is the
responsibility of the user of this standard to establish appro- with all the associated process hardware required for filtration.
F740
priate safety and health practices and determine the applica-
bility of regulatory limitations prior to use.
1 2
This guide is under the jurisdiction ofASTM Committee D18 on Soil and Rock For referenced ASTM standards, visit the ASTM website, www.astm.org, or
and is the direct responsibility of Subcommittee D18.21 on Groundwater and contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Vadose Zone Investigations. Standards volume information, refer to the standard’s Document Summary page on
Current edition approved May 15, 2012. Published December 2012. Originally the ASTM website.
approved in 2000. Last previous edition approved in 2005 as D6564 – 00 (2005). The last approved version of this historical standard is referenced on
DOI: 10.1520/D6564-00R12E01. www.astm.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
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D6564 − 00 (2012)
3.2.6 filtrate—the fluid that has passed through the filter. configurations. Groundwater samples undergo pressure
F740 changes as they are brought from the saturated zone (where
groundwater is under pressure greater than atmospheric) to the
3.2.7 filtration—the process by which particles are sepa-
surface (where it is under atmospheric pressure), resulting in
rated from a fluid by passing the fluid through a permeable
changes in sample chemistry. Vacuum filtration methods fur-
material. F740
ther exacerbate pressure changes. For this reason, positive
3.2.8 filtered sample—a groundwater sample which has
pressure filtration methods are preferred. Table 1 presents
passed through a filter medium.
equipment options available for positive pressure and vacuum
3.2.8.1 Discussion—This type of sample may also be re-
filtration of groundwater samples. Fig. 1 presents examples of
ferred to as a “dissolved” sample. An unfiltered sample
common filter characteristics and applications.
containing dissolved, sorbed, coprecipitated and all suspended
7.1.2 When selecting a filtration method, the following
particles may be referred to as a “total” sample.
criteria should be evaluated on a site-by-site basis:
3.2.9 particle—a small discrete mass of solid or liquid
7.1.2.1 Effect on sample integrity considering the potential
matter. F740
for the following to occur:
7.1.2.2 Sample aeration (Note 2),
4. Significance and Use
7.1.2.3 Sample agitation (Note 2),
4.1 A properly designed, installed and developed ground-
NOTE 2—Sample aeration and increased agitation may result in sample
water monitoring well, constructed in accordance with Practice
chemical alteration.
D5092, should facilitate collection of samples of groundwater
7.1.2.4 Change in partial pressure of sample constituents
that can be analyzed to determine both the physical and
resulting from application of negative pressure to the sample
chemical properties of that sample. Samples collected from
during filtration,
these wells that require analysis for dissolved constituents
7.1.2.5 Sorptive losses of components from the sample onto
shouldbefilteredinthefieldpriortochemicalpreservationand
the filter medium or components of the filtration equipment
shipment to the laboratory for analysis.
(for example, flasks, filter holders etc.); and
7.1.2.6 Leaching of components from the filter medium or
5. Purpose of Groundwater Sample Filtration
components of the filtration equipment into the sample.
5.1 Groundwater samples may be filtered to separate a
7.1.2.7 Volume of sample to be filtered;
defined fraction of the sample for analysis.
7.1.2.8 Chemical compatibility of filter medium with
groundwater sample chemistry;
6. Timing of Groundwater Sample Filtration
7.1.2.9 Anticipated amount of suspended solids and the
6.1 Groundwater samples should be filtered immediately
attendant effects of particulate loading (reduction in effective
upon collection and prior to chemical preservation of the
filter pore size);
sample. (1) Filtration should be completed in as short a time
7.1.2.10 Time required to filter samples (Note 3);
as possible while minimizing sample aeration, agitation, pres-
NOTE 3—Short filtration times are recommended to minimize the time
sure changes, temperature changes and prolonged contact with
available for chemical changes to occur in the sample.
ambient air.
7.1.2.11 Ease of use;
NOTE 1—The pressure change that occurs when the sample is brought
7.1.2.12 Availability of an appropriate medium in the de-
to the surface may cause changes in sample chemistry which include
sired filter pore size
losses of dissolved gases and precipitation of dissolved constituents such
7.1.2.13 Filter surface area;
as metals. When handling samples during filtration operations, additional
turbulence and mixing of the sample with air can cause aeration and
7.1.2.14 Use of disposable versus non-disposable equip-
oxidation of dissolved ferrous to ferric iron. Ferric iron rapidly precipi-
ment;
tates as amorphous iron hydroxide and can absorb other dissolved trace
7.1.2.15 Ease of cleaning equipment if not disposable;
metals (2).
7.1.2.16 Potential for sample bias associated with ambient
7. Groundwater Sample Filtration Procedures air contact during sample filtration; and
7.1.2.17 Cost, evaluating the costs associated with: equip-
7.1 Preparation for Groundwater Sample Filtration—The
ment purchase price, expendable supplies and their disposal,
groundwater sample filtration process consists of three phases:
selection of filtration method; selection and pretreatment of
filter media; and groundwater sample filtration prior to transfer TABLE 1 Examples of Equipment Options for Positive and
Negative Pressure Filtration of Groundwater Samples
into the sample container.
Positive Pressure Filtration Equipment:
7.1.1 Filtration Method Selection Criteria—A wide variety
In-line capsules
of methods are available for field filtration of groundwater
attached directly to a pumping device discharge hose
samples. In general, filtration equipment can be divided into
attached to a pressurized transfer vessel
positive pressure filtration and vacuum (negative pressure) attached to a pressurized bailer
Free-standing disk filter holders
filtrationmethods,eachwithseveraldifferentfiltrationmedium
Syringe filters
Zero headspace extraction vessels
Negative Pressure Filtration Equipment:
The boldface numbers given in parentheses refer to a list of references at the Glass funnel support assembly
end of the text.
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D6564 − 00 (2012)
FIG. 1 Examples of Common Filter Characteristics and Applications
time required for filtration, time required for decontamination using a medium with a pore size that meets the requirements of
of non-disposable equipment and quality control measures. the approved sampling and analysis plan.
7.1.2.18 The filtration method used for any given sampling
7.1.5 Preconditioning of the Filtration Medium:
program should be documented in the site-specific sampling
7.1.5.1 Filter media require preconditioning prior to sample
and analysis plan and should be consistent throughout the life
filtration (7). Purposes of filter preconditioning include: to
of the sampling program to permit comparison of data gener-
minimize positive sample bias associated with residues that
ated. If an improved method of filtration is determined to be
may exist on the filter surface or constituents that may leach
appropriate for a sampling program, the sampling and analysis
from the filter; and to create a uniform wetting front across the
plan should be revised and implemented in lieu of continuation
entire surface of the filter to prevent channel flow through the
of the existing filtration method. In this event, the effect on
filter and increase the efficiency of the filter surface area.
comparability of data needs to be examined and quantified to
Preconditioning the filter medium may not completely prevent
allow proper data analysis and interpretation (Note 4).
sorptive losses from the sample as it passes through the filter
medium.
NOTE 4—Statistical methods may need to be implemented to determine
thesignificanceofanychangesindataresultingfromachangeinfiltration
7.1.5.2 In most cases, filter preconditioning should be done
method.
at the wellhead (Note 5) immediately prior to use. Some
7.1.3 Filtration Equipment Materials of Construction—
manufacturers prerinse filters prior to sale. These filters are
Filtration equipment and filtration media are available in a
typically marked “prerinsed” on filter packaging and provide
wide variety of materials of construction. Materials of con-
directions for any additional field preconditioning required
struction should be evaluated (for example, by contacting
prior to filter use.
manufacturers, conducting leach tests or collecting equipment
NOTE 5—Some filters require preconditioning procedures that can only
blanks) to minimize sample bias:
be done in the laboratory (for example, GF/F filters must be baked prior
7.1.3.1 Potential for negative bias due to adsorption of
to use).
constituents from the sample (2);
7.1.5.3 The procedure used to precondition the filter me-
7.1.3.2 Potential for positive bias due to desorption or
dium is determined by the following: the design of the filter
leaching of constituents into the sample (3-6);
(thatis,filtercapsules,ordisks),thematerialofconstructionof
7.1.3.3 Reduction of the effective filter pore size caused by
the filter medium, the configuration of the filtration equipment,
clogging when filtering water containing suspended particles;
and the parameters of concern for sample analysis. Filtration
(6) and
medium manufacturers’ instructions should be followed prior
7.1.3.4 Aeration of the sample leading to precipitation of
to implementing any filter preconditioning protocols in the
some constituents (for example, ferric hydroxide) (3).
field to ensure that proper methods are employed and to
7.1.4 Selection and Pretreatment of Filter Media—Filtration
minimize potential bias of samples being filtered.
media are manufactured with specific pore size diameters
designed to permit particles of a selected size to be retained by 7.1.5.4 Thevolumeofwaterusedinfilterpreconditioningis
the filter medium. Filtration media must be selected after dependent upon the surface area of the filter and the medium’s
considering filter pore size, and materials of construction. abilitytoabsorbliquid.Manyfiltermediabecomefragilewhen
Groundwater samples requiring field filtration must be filtered saturated and are highly subject to damage during handling.
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D6564 − 00 (2012)
Therefore, saturated filter media should be handled carefully 7.2.2.4 Initiate and gradually increase the flow of water
and are best preconditioned immediately prior to use. through the filter to reach the appropriate rate and pressure, not
to exceed the maximum recommended by the filtration equip-
7.1.6 Preconditioning of Disk Filters—Disk filters (also
ment manufacturer (for example, 450 kPa (< 65 psi)) pressure
known as plate filters) should be preconditioned as follows:
for many capsule filters);
7.1.6.1 Hold the edge of the filter with filter forceps con-
7.2.2.5 Collect the filtered groundwater sample directly into
st
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