ASTM D6564-00(2005)
(Guide)Standard Guide for Field Filtration of Groundwater Samples
Standard Guide for Field Filtration of Groundwater Samples
SIGNIFICANCE AND USE
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
Designation: D6564 − 00(Reapproved 2005)
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.
1. Scope 2. Referenced Documents
2.1 ASTM Standards:
1.1 This guide covers methods for field filtration of ground-
D653 Terminology Relating to Soil, Rock, and Contained
water samples collected from groundwater monitoring wells,
Fluids
excluding samples that contain non-aqueous phase liquids
D5088 Practice for Decontamination of Field Equipment
(either Dense Non-Aqueous Phase Liquids (DNAPLs) or Light
Used at Waste Sites
Non-Aqueous Phase Liquids (LNAPLs)). Methods of field
D5092 Practice for Design and Installation of Ground Water
filtration described herein could also be applied to samples
Monitoring Wells
collected from wells used for other purposes. Laboratory
D5903 Guide for Planning and Preparing for a Groundwater
filtration methods are not described in this guide.
Sampling Event
1.2 This guide provides procedures available for field filtra-
D6089 Guide for Documenting a Ground-Water 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
3.1 filter, v—to pass a fluid containing particles through a
regulatory agency guidelines, and analytical method require-
filter medium whereby particles are separated from the fluid.
ments.
F740
1.3 This guide offers an organized collection of information
3.2 filter, n—a device for carrying out filtration which
oraseriesofoptionsanddoesnotrecommendaspecificcourse
consists of the combination of the filter medium and suitable
of action. This guide cannot replace education or experience
hardware for constraining and supporting it in the path of the
and should be used in conjunction with professional judgment.
fluid. F740
Not all aspects of this guide may be applicable in all circum-
3.3 filter medium—the permeable material used for a filter
stances. This guide is not intended to represent or replace the
that separates particles from a fluid passing through it. F740
standard of care by which the adequacy of a given professional
3.4 filter preconditioning—the process of preparing a filter
service must be judged, nor should this guide be applied
medium for filtration
without consideration of the many unique aspects of a project.
The word “Standard” in the title of this guide means only that 3.5 filter system—the combination of one or more filter with
alltheassociatedprocesshardwarerequiredforfiltration. F740
the guide has been approved through the ASTM consensus
process.
3.6 filtrate—thefluidthathaspassedthroughthefilter. F740
1.4 This standard does not purport to address all of the
3.7 filtration—the process by which particles are separated
safety concerns, if any, associated with its use. It is the
from a fluid by passing the fluid through a permeable material.
responsibility of the user of this standard to establish appro-
F740
priate safety and health practices and determine the applica-
3.8 filtered sample—a groundwater sample which has
bility of regulatory limitations prior to use.
passed through a filter medium.
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 Nov. 1, 2005. Published December 2005. Originally the ASTM website.
approved in 2000. Last previous edition approved in 2000 as D6564 – 00. DOI: The last approved version of this historical standard is referenced on
10.1520/D6564-00R05. www.astm.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D6564 − 00 (2005)
TABLE 1 Examples of Equipment Options for Positive and
3.8.1 Discussion—This type of sample may also be referred
Negative Pressure Filtration of Groundwater Samples
to as a “dissolved” sample. An unfiltered sample containing
Positive Pressure Filtration Equipment:
dissolved, sorbed, coprecipitated and all suspended particles
In-line capsules
may be referred to as a “total” sample.
attached directly to a pumping device discharge hose
attached to a pressurized transfer vessel
3.9 particle—a small discrete mass of solid or liquid matter.
attached to a pressurized bailer
F740
Free-standing disk filter holders
Syringe filters
Zero headspace extraction vessels
4. Significance and Use
Negative Pressure Filtration Equipment:
4.1 A properly designed, installed and developed ground-
Glass funnel support assembly
water 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
turbulence and mixing of the sample with air can cause aeration and
chemical properties of that sample. Samples collected from
oxidation of dissolved ferrous to ferric iron. Ferric iron rapidly precipi-
tates as amorphous iron hydroxide and can adsorb other dissolved trace
these wells that require analysis for dissolved constituents
metals (2).
shouldbefilteredinthefieldpriortochemicalpreservationand
shipment to the laboratory for analysis.
7. Groundwater Sample Filtration Procedures
7.1 Preparation for Groundwater Sample Filtration—The
5. Purpose of Groundwater Sample Filtration
groundwater sample filtration process consists of three phases:
5.1 Groundwater samples may be filtered to separate a
selection of filtration method; selection and pretreatment of
defined fraction of the sample for analysis.
filter media; and groundwater sample filtration prior to transfer
into the sample container.
6. Timing of Groundwater Sample Filtration
7.1.1 Filtration Method Selection Criteria—A wide variety
6.1 Groundwater samples should be filtered immediately
of methods are available for field filtration of groundwater
upon collection and prior to chemical preservation of the
samples. In general, filtration equipment can be divided into
sample. (1) Filtration should be completed in as short a time
positive pressure filtration and vacuum (negative pressure)
as possible while minimizing sample aeration, agitation, pres-
filtrationmethods,eachwithseveraldifferentfiltrationmedium
sure changes, temperature changes and prolonged contact with
configurations. Groundwater samples undergo pressure
ambient air.
changes as they are brought from the saturated zone (where
NOTE 1—The pressure change that occurs when the sample is brought groundwater is under pressure greater than atmospheric) to the
to the surface may cause changes in sample chemistry which include
surface (where it is under atmospheric pressure), resulting in
losses of dissolved gases and precipitation of dissolved constituents such
changes in sample chemistry. Vacuum filtration methods fur-
as metals. When handling samples during filtration operations, additional
ther exacerbate pressure changes. For this reason, positive
pressure filtration methods are preferred. Table 1 presents
equipment options available for positive pressure and vacuum
The boldface numbers given in parentheses refer to a list of references at the filtration of groundwater samples. Fig. 1 presents examples of
end of the text.
FIG. 1 Examples of Common Filter Characteristics and Applications
D6564 − 00 (2005)
common filter characteristics and applications. manufacturers, conducting leach tests or collecting equipment
blanks) to minimize sample bias:
7.1.2 When selecting a filtration method, the following
criteria should be evaluated on a site-by-site basis:
7.1.3.1 Potential for negative bias due to adsorption of
7.1.2.1 Effect on sample integrity considering the potential
constituents from the sample (2);
for the following to occur:
7.1.3.2 Potential for positive bias due to desorption or
7.1.2.2 Sample aeration (Note 2),
leaching of constituents into the sample (3-6);
7.1.2.3 Sample agitation (Note 2),
7.1.3.3 Reduction of the effective filter pore size caused by
clogging when filtering water containing suspended particles;
NOTE 2—Sample aeration and increased agitation may result in sample
chemical alteration.
(6) and
7.1.3.4 Aeration of the sample leading to precipitation of
7.1.2.4 Change in partial pressure of sample constituents
resulting from application of negative pressure to the sample some constituents (for example, ferric hydroxide) (3).
during filtration,
7.1.4 Selection and Pretreatment of Filter Media—Filtration
7.1.2.5 Sorptive losses of components from the sample onto
media are manufactured with specific pore size diameters
the filter medium or components of the filtration equipment
designed to permit particles of a selected size to be retained by
(for example, flasks, filter holders etc.); and
the filter medium. Filtration media must be selected after
7.1.2.6 Leaching of components from the filter medium or
considering filter pore size, and materials of construction.
components of the filtration equipment into the sample. Groundwater samples requiring field filtration must be filtered
7.1.2.7 Volume of sample to be filtered; using a medium with a pore size that meets the requirements of
7.1.2.8 Chemical compatibility of filter medium with the approved sampling and analysis plan.
groundwater sample chemistry;
7.1.5 Preconditioning of the Filtration Medium:
7.1.2.9 Anticipated amount of suspended solids and the
7.1.5.1 Filter media require preconditioning prior to sample
attendant effects of particulate loading (reduction in effective
filtration (7). Purposes of filter preconditioning include: to
filter pore size);
minimize positive sample bias associated with residues that
7.1.2.10 Time required to filter samples (Note 3);
may exist on the filter surface or constituents that may leach
from the filter; and to create a uniform wetting front across the
NOTE 3—Short filtration times are recommended to minimize the time
available for chemical changes to occur in the sample. entire surface of the filter to prevent channel flow through the
filter and increase the efficiency of the filter surface area.
7.1.2.11 Ease of use;
Preconditioning the filter medium may not completely prevent
7.1.2.12 Availability of an appropriate medium in the de-
sorptive losses from the sample as it passes through the filter
sired filter pore size
medium.
7.1.2.13 Filter surface area;
7.1.5.2 In most cases, filter preconditioning should be done
7.1.2.14 Use of disposable versus non-disposable equip-
at the wellhead (Note 5) immediately prior to use. Some
ment;
manufacturers prerinse filters prior to sale. These filters are
7.1.2.15 Ease of cleaning equipment if not disposable;
typically marked “prerinsed” on filter packaging and provide
7.1.2.16 Potential for sample bias associated with ambient
directions for any additional field preconditioning required
air contact during sample filtration; and
prior to filter use.
7.1.2.17 Cost, evaluating the costs associated with: equip-
ment purchase price, expendable supplies and their disposal,
NOTE 5—Some filters require preconditioning procedures that can only
be done in the laboratory (for example, GF/F filters must be baked prior
time required for filtration, time required for decontamination
to use).
of non-disposable equipment and quality control measures.
7.1.2.18 The filtration method used for any given sampling
7.1.5.3 The procedure used to precondition the filter me-
program should be documented in the site-specific sampling
dium is determined by the following: the design of the filter
and analysis plan and should be consistent throughout the life
(thatis,filtercapsules,ordisks),thematerialofconstructionof
of the sampling program to permit comparison of data gener-
the filter medium, the configuration of the filtration equipment,
ated. If an improved method of filtration is determined to be
and the parameters of concern for sample analysis. Filtration
appropriate for a sampling program, the sampling and analysis
medium manufacturers’ instructions should be followed prior
plan should be revised and implemented in lieu of continuation
to implementing any filter preconditioning protocols in the
of the existing filtration method. In this event, the effect on
field to ensure that proper methods are employed and to
comparability of data needs to be examined and quantified to
minimize potential bias of samples being filtered.
allow proper data analysis and interpretation (Note 4).
7.1.5.4 Thevolumeofwaterusedinfilterpreconditioningis
dependent upon the surface area of the filter and the medium’s
NOTE 4—Statistical methods may need to be implemented to determine
thesignificanceofanychangesindataresultingfromachangeinfiltration abilitytoabsorbliquid.Manyfiltermediabecomefragilewhen
method.
saturated and are highly subject to damage during handling.
Therefore, saturated filter media should be handled carefully
7.1.3 Filtration Equipment Materials of Construction—
and are best preconditioned immediately prior to use.
Filtration equipment and filtration media are available in a
wide variety of materials of construction. Materials of con- 7.1.6 Preconditioning of Disk Filters—Disk filters (also
struction should be evaluated (for example, by contacting known as plate filters) should be preconditioned as follows:
D6564 − 00 (2005)
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
structed of materials that are appropriate for the analytes of a prepared sample bottle;
interest (Note 6);
7.2.2.6 Preserve the filtered groundwater sample as required
on a parameter-specific basis;
NOTE 6—Manufacturers often use colored parchment paper disks (for
example, yellow or blue) to separate filter disks and these should not be 7.2.2.7 Release the pressure from the filtration equipment
confused with the filtration medium.
and disconnect it from the sampling device discharge hose;
7.1.6.2 Saturate the entire filter disk with wat
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