ASTM D5980-96(2004)
(Guide)Standard Guide for Selection and Documentation of Existing Wells for Use in Environmental Site Characterization and Monitoring
Standard Guide for Selection and Documentation of Existing Wells for Use in Environmental Site Characterization and Monitoring
SIGNIFICANCE AND USE
This guide describes a general approach for the use of existing wells in environmental investigations with a primary focus on the subsurface and major factors affecting the surface and subsurface environment.
Existing wells represent a valuable source of information for subsurface environmental investigations. Specific uses of existing wells include:
4.2.1 Well driller logs provide information on subsurface lithology and major water-bearing units in an area. Existing wells can also offer access for downhole geophysical logging for stratigraphic and aquifer interpretations. Examples include natural gamma logs in cased wells and an entire suite of methods in uncased bedrock wells (see Guide D 5753). This information can assist in developing the preliminary conceptual model of the site.
4.2.2 Well tests using existing wells may provide information on the hydrologic characteristics of an aquifer.
4.2.3 Monitoring of water levels in existing wells, provided that they are cased in the aquifer of interest, allow development of potentiometric maps and interpretations of ground-water flow directions.
4.2.4 Existing wells are the primary means by which regional drinking water quality is evaluated and monitored.
4.2.5 Existing wells may assist in the mapping of contaminant plumes, and in ongoing monitoring of ground-water quality changes at the site-specific level.
Data from existing wells should only be used when characteristics of the well have been sufficiently documented to determine that they satisfy criteria for the purpose for which the data are to be used.
SCOPE
1.1 This guide covers the use of existing wells for environmental site characterization and monitoring. It covers the following major topics: criteria for determining the suitability of existing wells for hydrogeologic characterization and ground-water quality monitoring, types of data required to document the suitability of an existing well, and the relative advantages and disadvantages of existing large- and small-capacity wells.
1.2 This guide should be used in conjunction with Guide D 5730, that provides a general approach for environmental site investigations.
1.3 This guide does not specifically address design and construction of new monitoring or supply wells. Refer to Practices D 5092 and D 5787.
1.4 This guide does not specifically address ground-water sampling procedures. Refer to Guide D 5903.
1.5 The values stated in SI units are to be regarded as the standard. However, dimensions of materials used in the water well industry are given in inch-pound (English) units by convention; therefore, inch-pound units are used where necessary in this guide.
1.6 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.
1.7 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 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.
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Designation: D5980 – 96 (Reapproved 2004)
Standard Guide for
Selection and Documentation of Existing Wells for Use in
Environmental Site Characterization and Monitoring
This standard is issued under the fixed designation D5980; 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 aspects. The word “Standard” in the title of this document
means only that the document has been approved through the
1.1 This guide covers the use of existing wells for environ-
ASTM consensus process.
mental site characterization and monitoring. It covers the
following major topics: criteria for determining the suitability
2. Referenced Documents
of existing wells for hydrogeologic characterization and
2.1 Pertinent guides addressing specific information neces-
ground-water quality monitoring, types of data required to
sary to utilize existing wells for hydrologic and water-quality
document the suitability of an existing well, and the relative
data for environmental site characterization. A comprehensive
advantages and disadvantages of existing large- and small-
listofguides,standards,methods,practices,andterminologyis
capacity wells.
contained in Guide D5730. Other guidance documents cover-
1.2 This guide should be used in conjunction with Guide
ing procedures for environmental site investigations with
D5730, that provides a general approach for environmental site
specific objectives or in particular geographic settings may be
investigations.
available from federal, state, and other agencies or organiza-
1.3 This guide does not specifically address design and
tions. The appropriate agency or organization should be
construction of new monitoring or supply wells. Refer to
contactedtodeterminetheavailabilityandmostcurrentedition
Practices D5092 and D5787.
of such documents.
1.4 This guide does not specifically address ground-water
2.2 ASTM Standards:
sampling procedures. Refer to Guide D5903.
D653 Terminology Relating to Soil, Rock, and Contained
1.5 The values stated in SI units are to be regarded as the
Fluids
standard. However, dimensions of materials used in the water
D4750 Test Method for Determining Subsurface Liquid
well industry are given in inch-pound (English) units by
Levels in a Borehole or Monitoring Well (Observation
convention; therefore, inch-pound units are used where neces-
Well)
sary in this guide.
D5092 PracticeforDesignandInstallationofGroundWater
1.6 This standard does not purport to address all of the
Monitoring Wells
safety concerns, if any, associated with its use. It is the
D5254 Practice for Minimum Set of Data Elements to
responsibility of the user of this standard to establish appro-
Identify a Ground-Water Site
priate safety and health practices and determine the applica-
D5408 Guide for Set of Data Elements to Describe a
bility of regulatory limitations prior to use.
Ground-Water Site; Part One—Additional Identification
1.7 This guide offers an organized collection of information
Descriptors
or a series of options and does not recommend a specific
D5409 Guide for Set of Data Elements to Describe a
course of action. This guide cannot replace education or
Ground-Water Site; Part Two—Physical Descriptors
experience and should be used in conjunction with professional
D5410 Guide for Set of Data Elements to Describe a
judgment. Not all aspects of this guide may be applicable in all
Ground-Water Site;Part Three—Usage Descriptors
circumstances. This guide is not intended to represent or
D5474 Guide for Selection of Data Elements for Ground-
replace the standard of care by which the adequacy of a given
Water Investigations
professional service must be judged, nor should this guide be
D5521 Guide for Development of Ground-Water Monitor-
applied without consideration of a project’s many unique
ing Wells in Granular Aquifers
This guide is under the jurisdiction ofASTM Committee D18 on Soil and Rock
and is the direct responsibility of Subcommittee D18.21 on Ground Water and For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Vadose Zone Investigations. contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Current edition approved May 1, 2004. Published May 2004. Originally Standards volume information, refer to the standard’s Document Summary page on
´1
approved in 1996. Last previous edition approved in 1996 as D5980 - 96 . DOI: the ASTM website.
10.1520/D5980-96R04. Withdrawn.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D5980 – 96 (2004)
D5730 Guide for Site Characterization for Environmental 4.2.5 Existing wells may assist in the mapping of contami-
Purposes With Emphasis on Soil, Rock, the Vadose Zone nant plumes, and in ongoing monitoring of ground-water
and Ground Water quality changes at the site-specific level.
D5753 Guide for Planning and Conducting Borehole Geo- 4.3 Data from existing wells should only be used when
physical Logging characteristicsofthewellhavebeensufficientlydocumentedto
D5787 Practice for Monitoring Well Protection determine that they satisfy criteria for the purpose for which
D5903 GuideforPlanningandPreparingforaGroundwater the data are to be used.
Sampling Event
5. General Considerations in Selection and Use of
D5978 Guide for Maintenance and Rehabilitation of
Existing Wells
Ground-Water Monitoring Wells
5.1 Selection and use of existing wells should take place in
D5979 Guide for Conceptualization and Characterization of
the context of a conceptual framework consisting of a descrip-
Ground-Water Systems
tion of the system, including, as necessary, physical and
cultural characteristics, such as climate, hydrology, ecology,
3. Terminology
physiography, population, water use and land use, and hypoth-
3.1 Definitions—Except as noted below, all definitions are
eses about processes of interest that occur within that system.
in accordance with Terminology D653:
A step-wise approach for conceptualization and characteriza-
3.1.1 aquifer, n—a geologic formation, group of forma-
tion is a direct approach to develop the framework for
tions, or part of a formation that is saturated and is capable of
Hydrologic Systems as described in Kolm (1) , (see Guide
providing a significant quantity of water (see Practice D5092).
D5979). Conceptualization of hydrologic and regional ground-
3.1.2 monitoring well (observation well), n—a special well
water quality systems can be formulated using the methods
drilled in a selected location for observing parameters such as
outlined in Alley (2). The framework is reviewed and refined
liquid level or pressure changes or for collecting liquid
by an iterative process of data collection and analysis, testing
samples. The well may be cased or uncased, but if cased, the
hypotheses with data collected, and identifying data needs to
casing should have openings to allow flow of borehole liquid
further revise the framework. Refinement must be made within
into or out of the casing.
the limits established by the accuracy, precision, and complete-
3.1.3 observation well, n—for the purposes of this guide, an
ness of the data. Methods for data collection are selected that
existing well constructed for other purposes that is also used to
will provide data appropriate for testing hypotheses which
measure water levels and to collect ground-water quality
evaluate the conceptual framework.
samples. Observation well may be referred to as “well” in this
5.2 Well design and installation can critically affect the
guide.
quality of water level measurements and ground-water
3.1.4 supply (production) well, n—well primarily installed
samples. Such effects apply both to existing wells and to wells
for public supply, irrigation, and industrial use. Supply wells
specifically installed for a purpose. The effects of well design
may be used as an observation well.
and installation, therefore, need to be considered regardless of
whether existing wells are selected or if wells are specifically
4. Significance and Use
installedforaspecificpurpose.Themostcommonfeatureofan
4.1 This guide describes a general approach for the use of
existing well that may render it unsuitable for water level
existing wells in environmental investigations with a primary
measurement or water-quality monitoring is that multiple
focus on the subsurface and major factors affecting the surface
hydrogeologic units are connected causing water levels and
and subsurface environment.
water-quality parameters to reflect a mixing of multiple hydro-
4.2 Existing wells represent a valuable source of informa-
geologic units. Such data cannot be reliably compared with
tion for subsurface environmental investigations. Specific uses
data from wells completed in the individual hydrogeologic
of existing wells include:
units.
4.2.1 Well driller logs provide information on subsurface
5.3 Major steps in the selection of existing wells for
lithology and major water-bearing units in an area. Existing
environmental investigations include: developing specific cri-
wells can also offer access for downhole geophysical logging
teria for evaluating the suitability of existing wells in relation
for stratigraphic and aquifer interpretations. Examples include
to the objectives of the investigations (see Section 6), conduct-
natural gamma logs in cased wells and an entire suite of
ing an inventory of existing wells in the area of interest (see
methods in uncased bedrock wells (see Guide D5753). This
8.1), documenting the characteristics of the wells identified in
information can assist in developing the preliminary concep-
the inventory that are relevant to the selection criteria (see8.2),
tual model of the site.
and identification of wells that satisfy the selection criteria (see
4.2.2 Well tests using existing wells may provide informa-
Section 9).
tion on the hydrologic characteristics of an aquifer.
6. Well-Selection Criteria
4.2.3 Monitoring of water levels in existing wells, provided
6.1 Assessing the suitability of existing wells for hydrologi-
thattheyarecasedintheaquiferofinterest,allowdevelopment
cal and ground-water quality studies requires development of
of potentiometric maps and interpretations of ground-water
flow directions.
4.2.4 Existing wells are the primary means by which re-
The boldface numbers in parentheses refer to the list of references at the end of
gional drinking water quality is evaluated and monitored. this standard.
D5980 – 96 (2004)
specific well-selection criteria. The criteria are based on 7. General Characteristics of Major Types of Existing
considerations of project objectives by defining the problem to Wells
be solved, the conceptual framework, and data-collection
7.1 There are two general categories of existing wells
requirements.
available for hydrologic and ground-water quality studies:
6.2 Specific Well-Selection Criteria—Specific criteria will
large- and small-capacity supply or production wells installed
depend on the objectives of the investigation. The following
fordrinking,irrigation,andindustrialuse(see7.2and7.3);and
general criteria will apply to most situations:
wells specially designed and installed to monitor hydrologic or
6.2.1 The well is suitably located for use in relation to the
water-quality studies, or both (see 7.4). Each type of well has
conceptual framework.
its own general advantages and disadvantages.
6.2.2 The well must be completed in the targeted hydrogeo-
7.2 Large-Capacity Supply Wells—Large-capacity supply
logic unit or units.
wells are usually developed for drinking water systems that
6.2.3 Welldesignandconstructionmustnotbiaswaterlevel
supply multiple households, and for irrigation and industrial
measurements or water-quality sampling results (see Note 1).
purposes.
Section7providesinformationonthegeneralcharacteristicsof
7.2.1 Advantages:
major types of existing wells.
7.2.1.1 Documentation of well construction commonly is
good.
NOTE 1—Gillham et al. (3), provides information on the suitability of
materials coming in contact with water samples and that table provides
7.2.1.2 Large-capacity wells generally are well developed
information on the compatibility of well casing materials with different
and fully purged.
organic contaminants.
7.2.1.3 Long-term access may be possible, particularly for
6.2.4 The well is accessible for measurements and sam-
municipal wells.
pling.
7.2.1.4 Large-capacity wells generally provide a larger ver-
6.2.5 The well’s maintenance condition may not compro-
tical mix of water in an aquifer or aquifer system than
mise it as a sampling point; however, there are examples that
small-capacity wells, and thus can provide a more integrated
may compromise it as a sampling point, that is, a cracked
measure of regional ground-water quality than small-capacity
casing allowing non-screened water into the well.
wells.
6.3 Examples of Well Selection Criteria—The following are
7.2.1.5 Much of the water produced for irrigation and
illustrative examples of criteria for specific investigation ob-
municipal water is from large-capacity wells equipped with
jectives (see Note 2).
taps which allow a direct sample of the pumped water.
7.2.1.6 Long-term water-quality and quantity data may be
NOTE 2—These are illustrative examples and should not be construed
as recommended criteria. available.
7.2.2 Disadvantages:
6.3.1 A project to determine the quality of potable ground
7.2.2.1 Large-capacity wells may not have flow-rate con-
water might require the following selection criteria: wells
trols and a sampling point near the well head.
selected must be used for public water supply, must be
7.2.2.2 High pumping rates may entrain artifacts, such as
geographically distributed over the entire aquifer of interest,
colloids or suspended material, into the sample stream.
and must be able to be sampled prior to any water treatment.
7.2.2.3 Pumping schedules could be irregular: for example,
6.3.2 All wells or a subset of wells down-gradient from a
irrigation wells generally are pumped seasonally, and could
hazardous-waste site would be unsuitable to include in a
lead to seasonal variations in water quality that actually are an
network designed for a study to determine non-point source
artifact of the pumping regime.
ground-water quality.
7.2.2.4 Large capacity wells may have a long vertical gravel
6.3.3 Choosing a well located down-gradient of a complex
pack, screened or open intervals might span more than one
mix of land uses would be inappropriate in a study designed
...
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