ASTM D5980-96e1
(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
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.
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Designation: D 5980 – 96
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 D 5980; 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 (e) indicates an editorial change since the last revision or reapproval.
e NOTE—Paragraph 1.7 was added editorially October 1998.
1. Scope unique aspects. The word “Standard” in the title of this
document means only that the document has been approved
1.1 This guide covers the use of existing wells for environ-
through the 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 ASTM guides addressing specific information
ground-water quality monitoring, types of data required to
necessary to utilize existing wells for hydrologic and water-
document the suitability of an existing well, and the relative
quality data for environmental site characterization. A compre-
advantages and disadvantages of existing large- and small-
hensive list of guides, standards, methods, practices, and
capacity wells.
terminology is contained in Guide D 5730. Other guidance
1.2 This guide should be used in conjunction with Guide
documents covering procedures for environmental site inves-
D 5730, that provides a general approach for environmental
tigations with specific objectives or in particular geographic
site investigations.
settings may be available from federal, state, and other
1.3 This guide does not specifically address design and
agencies or organizations. The appropriate agency or organi-
construction of new monitoring or supply wells. Refer to
zation should be contacted to determine the availability and
Practices D 5092 and D 5787.
most current edition of such documents.
1.4 This guide does not specifically address ground-water
2.2 ASTM Standards:
sampling procedures. Refer to Guide D 5903.
D 653 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
D 4750 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.
D 5092 Practice for Design and Installation of Ground
1.6 This standard does not purport to address all of the
Water Monitoring Wells in Aquifers
safety concerns, if any, associated with its use. It is the
D 5254 Practice for a 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-
D 5408 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
D 5409 Guide for Set of Data Elements to Describe a
course of action. This document cannot replace education or
Ground-Water Site; Part Two—Physical Descriptors
experience and should be used in conjunction with professional
D 5410 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 ASTM standard is not intended to repre-
D 5474 Guide for Selection of Data Elements for Ground-
sent or replace the standard of care by which the adequacy of
Water Investigations
a given professional service must be judged, nor should this
D 5521 Guide for Development of Ground-Water Monitor-
document be applied without consideration of a project’s many
ing Wells in Granular Aquifers
This guide is under the jurisdiction of ASTM Committee D-18 on Soil and
Rockand is the direct responsibility of Subcommittee D18.21 on Ground Water and
Vadose Zone Investigations.
Current edition approved July 10, 1996. Published November 1996. Annual Book of ASTM Standards, Vol 04.08.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
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D5980–96
D 5730 Guide to Site Characterization for Environmental 4.2.4 Existing wells are the primary means by which re-
Purposes with Emphasis on Soil, Rock, the Vadose Zone, gional drinking water quality is evaluated and monitored.
and Ground Water 4.2.5 Existing wells may assist in the mapping of contami-
D 5753 Guide for Planning and Conducting Borehole Geo- nant plumes, and in ongoing monitoring of ground-water
physical Logging quality changes at the site-specific level.
D 5787 Practice for Monitoring Well Protection 4.3 Data from existing wells should only be used when
D 5903 Guide for Planning and Preparing for a Ground- characteristics of the well have been sufficiently documented to
Water Sampling Event determine that they satisfy criteria for the purpose for which
D 5978 Guide for Maintenance and Rehabilitation of the data are to be used.
Ground Water Monitoring Wells
5. General Considerations in Selection and Use of
D 5979 Guide for Conceptualization and Characterization
3 Existing Wells
of Ground-Water Systems
5.1 Selection and use of existing wells should take place in
3. Terminology
the context of a conceptual framework consisting of a descrip-
tion of the system, including, as necessary, physical and
3.1 Definitions—Except as noted below, all definitions are
in accordance with Terminology D 653: cultural characteristics such as climate, hydrology, ecology,
physiography, population, water use and land use, and hypoth-
3.1.1 aquifer, n—a geologic formation, group of forma-
tions, or part of a formation that is saturated and is capable of eses about processes of interest that occur within that system.
A step-wise approach for conceptualization and characteriza-
providing a significant quantity of water (see Practice D 5092).
3.1.2 monitoring well (observation well), n—a special well tion is a direct approach to develop the framework for
Hydrologic Systems as described in Kolm (1), (see Guide
drilled in a selected location for observing parameters such as
liquid level or pressure changes or for collecting liquid D 5979). Conceptualization of hydrologic and regional
ground-water quality systems can be formulated using the
samples. The well may be cased or uncased, but if cased the
methods outlined in Alley (2). The framework is reviewed and
casing should have openings to allow flow of borehole liquid
refined by an iterative process of data collection and analysis,
into or out of the casing.
testing hypotheses with data collected, and identifying data
3.1.3 observation well, n—for the purposes of this guide, an
needs to further revise the framework. Refinement must be
existing well constructed for other purposes that is also used to
made within the limits established by the accuracy, precision,
measure water levels and to collect ground-water quality
and completeness of the data. Methods for data collection are
samples. Observation well may be referred to as 88well” in this
selected that will provide data appropriate for testing hypoth-
guide.
eses which evaluate the conceptual framework.
3.1.4 supply (production) well, n—well primarily installed
5.2 Well design and installation can critically affect the
for public supply, irrigation, and industrial use. Supply wells
quality of water level measurements and ground-water
may be used as an observation well.
samples. Such effects apply both to existing wells and to wells
4. Significance and Use
specifically installed for a purpose. The effects of well design
and installation, therefore, need to be considered regardless of
4.1 This guide describes a general approach for the use of
existing wells in environmental investigations with a primary whether existing wells are selected or if wells are specifically
installed for a specific purpose. The most common feature of an
focus on the subsurface and major factors affecting the surface
and subsurface environment. existing well that may render it unsuitable for water level
measurement or water-quality monitoring is that multiple
4.2 Existing wells represent a valuable source of informa-
tion for subsurface environmental investigations. Specific uses hydrogeologic units are connected causing water levels and
water-quality parameters to reflect a mixing of multiple hydro-
of existing wells include:
geologic units. Such data cannot be reliably compared with
4.2.1 Well driller logs provide information on subsurface
data from wells completed in the individual hydrogeologic
lithology and major water-bearing units in an area. Existing
units.
wells can also offer access for downhole geophysical logging
5.3 Major steps in the selection of existing wells for
for stratigraphic and aquifer interpretations. Examples include
environmental investigations include: developing specific cri-
natural gamma logs in cased wells and an entire suite of
teria for evaluating the suitability of existing wells in relation
methods in uncased bedrock wells (see Guide D 5753). This
to the objectives of the investigations (see Section 6), conduct-
information can assist in developing the preliminary concep-
ing an inventory of existing wells in the area of interest (see
tual model of the site.
8.1), documenting the characteristics of the wells identified in
4.2.2 Well tests using existing wells may provide informa-
the inventory that are relevant to the selection criteria (see 8.2),
tion on the hydrologic characteristics of an aquifer.
and identification of wells that satisfy the selection criteria (see
4.2.3 Monitoring of water levels in existing wells, provided
that they are cased in the aquifer of interest, allow development Section 9).
of potentiometric maps and interpretations of ground-water
6. Well-Selection Criteria
flow directions.
6.1 Assessing the suitability of existing wells for hydrologi-
cal and ground-water quality studies requires development of
Annual Book of ASTM Standards, Vol 04.09. specific well-selection criteria. The criteria are based on
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D5980–96
considerations of project objectives by defining the problem to 7. General Characteristics of Major Types of Existing
be solved, the conceptual framework, and data-collection Wells
requirements.
7.1 There are two general categories of existing wells
6.2 Specific Well-Selection Criteria—Specific criteria will
available for hydrologic and ground-water quality studies:
depend on the objectives of the investigation. The following
large- and small-capacity supply or production wells installed
general criteria will apply to most situations:
for drinking, irrigation, and industrial use (see 7.2 and 7.3); and
6.2.1 The well is suitably located for use in relation to the
wells specially designed and installed to monitor hydrologic or
conceptual framework.
water-quality studies, or both, (see 7.4). Each type of well has
6.2.2 The well must be completed in the targeted hydrogeo- its own general advantages and disadvantages.
logic unit or units.
7.2 Large-Capacity Supply Wells—Large capacity supply
6.2.3 Well design and construction must not bias water level wells are usually developed for drinking water systems that
measurements or water-quality sampling results (see Note 1). supply multiple households, and for irrigation and industrial
Section 7 provides information on the general characteristics of purposes.
major types of existing wells. 7.2.1 Advantages:
7.2.1.1 Documentation of well construction commonly is
NOTE 1—Gillham et al. (3), provides information on the suitability of
good.
materials coming in contact with water samples and that table provides
information on the compatibility of well casing materials with different 7.2.1.2 Large-capacity wells generally are well developed
organic contaminants.
and fully purged.
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.
NOTE 2—These are illustrative examples and should not be construed
7.2.1.6 Long-term water-quality and quantity data may be
as recommended criteria.
available.
7.2.2 Disadvantages:
6.3.1 A project to determine the quality of potable ground
water might require the following selection criteria: wells
7.2.2.1 Large-capacity wells may not have flow-rate con-
selected must be used for public water supply, must be trols and a sampling point near the well head.
geographically distributed over the entire aquifer of interest,
7.2.2.2 High pumping rates may entrain artifacts, such as
and must be able to be sampled prior to any water treatment.
colloids or suspended material, into the sample stream.
6.3.2 All wells or a subset of wells down-gradient from a
7.2.2.3 Pumping schedules could be irregular: for example,
hazardous-waste site would be unsuitable to include in a
irrigation wells generally are pumped seasonally, and could
network designed for a study to determine non-point source
lead to seasonal variations in water quality that actually are an
ground-water quality.
artifact of the pumping regime.
6.3.3 Choosing a well located down-gradient of a complex
7.2.2.4 Large capacity wells may have a long vertical gravel
mix of land uses would be inappropriate in a study designed to
pack, screened or open intervals might span more than one
assess the effects of specific land uses on ground-water quality.
aquifer or aquifer system, making them unsuitable for poten-
tiometric mapping or water quality monito
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