Standard Guide for Development of Groundwater Monitoring Wells in Granular Aquifers

SIGNIFICANCE AND USE
A properly designed, installed, and developed groundwater monitoring well, constructed in accordance with Practice D5092 should provide the following: representative samples of groundwater that can be analyzed to determine physical properties and water-quality parameters of the sample or potentiometric levels that are representative of the total hydraulic head of that portion of the aquifer screened by the well, or both. Such a well may also be utilized for conducting aquifer tests used for the purpose of determining the hydraulic properties of the geologic materials in which the well has been completed.
Well development is an important component of monitoring well completion. Monitoring wells installed in aquifers should be sufficiently developed to ensure that they serve their intended objectives. Well development methods vary with the physical characteristics of the geologic formation in which the monitoring well is screened, the construction details of the well, the drilling method used during the construction of the borehole in which the well is installed, and the quality of the water. The development method for each individual monitoring well should be selected from among the several methods described in this guide and should be employed by the well construction contractor or the person responsible for monitoring well completion.
The importance of well development in monitoring wells cannot be overestimated; all too often development is not performed or is carried out inadequately. Proper and careful well development will improve the ability of most monitoring wells to provide representative, unbiased chemical and hydraulic data. The additional time and money spent performing this important step in monitoring well completion will minimize the potential for damaging pumping equipment and in-situ sensors, and increase the probability that groundwater samples are representative of water contained in the monitored formation.
SCOPE
1.1 This guide covers the development of screened wells installed for the purpose of obtaining representative groundwater information and water quality samples from granular aquifers, though the methods described herein could also be applied to wells used for other purposes. Other well-development methods that are used exclusively in open-borehole bedrock wells are not described in this guide.
1.2 The applications and limitations of the methods described in this guide are based on the assumption that the primary objective of the monitoring wells to which the methods are applied is to obtain representative water quality samples from aquifers. Screened monitoring wells developed using the methods described in this guide should yield relatively sediment-free samples from granular aquifer materials, ranging from gravels to silty sands. While many monitoring wells are considered “small-diameter” wells (that is, less than four inches in inside diameter), some of the techniques described in this guide will be more easily applied to large-diameter wells (that is, four-inches or greater in inside diameter).
1.3 The values stated in inch-pound units are to be regarded as standard. All other units in parentheses are provided for information only.
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.
1.5 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 professio...

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ASTM D5521-05 - Standard Guide for Development of Groundwater Monitoring Wells in Granular Aquifers
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NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
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Designation: D5521 − 05
StandardGuide for
Development of Groundwater Monitoring Wells in Granular
1
Aquifers
This standard is issued under the fixed designation D5521; 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 sent or replace the standard of care by which the adequacy of
a given professional service must be judged, nor should this
1.1 This guide covers the development of screened wells
document be applied without consideration of a project’s many
installed for the purpose of obtaining representative ground-
unique aspects. The word “Standard” in the title of this
water information and water quality samples from granular
document means only that the document has been approved
aquifers, though the methods described herein could also be
through the ASTM consensus process.
applied to wells used for other purposes. Other well-
development methods that are used exclusively in open-
2. Referenced Documents
borehole bedrock wells are not described in this guide.
2
2.1 ASTM Standards:
1.2 The applications and limitations of the methods de-
D653 Terminology Relating to Soil, Rock, and Contained
scribed in this guide are based on the assumption that the
Fluids
primary objective of the monitoring wells to which the
D5088 Practice for Decontamination of Field Equipment
methods are applied is to obtain representative water quality
Used at Waste Sites
samples from aquifers. Screened monitoring wells developed
D5092 Practice for Design and Installation of Ground Water
using the methods described in this guide should yield rela-
Monitoring Wells
tively sediment-free samples from granular aquifer materials,
ranging from gravels to silty sands. While many monitoring
3. Terminology
wells are considered “small-diameter” wells (that is, less than
3.1 Definitions:
four inches in inside diameter), some of the techniques
3.1.1 Many of the terms discussed in this guide are con-
described in this guide will be more easily applied to large-
tained inTerminology D653.The reader should refer to this for
diameter wells (that is, four-inches or greater in inside diam-
definitions of selected terms.
eter).
3.2 Definitions of Terms Specific to This Standard:
1.3 The values stated in inch-pound units are to be regarded
3.2.1 air entrapment—trapping of air or other gas in pore
as standard. All other units in parentheses are provided for
spaces of the formation or filter pack during development with
information only.
compressed air.
1.4 This standard does not purport to address all of the
3.2.2 air lift pump—a device consisting of two pipes, with
safety concerns, if any, associated with its use. It is the
one (the air line) inside the other (the eductor pipe), used to
responsibility of the user of this standard to establish appro-
withdraw water from a well. The lower ends of the pipes are
priate safety and health practices and determine the applica-
submerged, and compressed air is delivered through the inner
bility of regulatory limitations prior to use.
pipe to form a mixture of air and water. This mixture rises in
1.5 This guide offers an organized collection of information
the outer pipe to the surface because the specific gravity of this
or a series of options and does not recommend a specific
mixture is less than that of the water column.
course of action. This document cannot replace education or
3.2.3 air line—a small vertical air pipe used in air-lift
experienceandshouldbeusedinconjunctionwithprofessional
pumping.Itusuallyextendsfromthegroundsurfacetonearthe
judgment. Not all aspects of this guide may be applicable in all
submerged lower end of the eductor pipe. The length of the air
circumstances. This ASTM standard is not intended to repre-
line below the static water level is used in calculating the air
pressure required to start air-lift pumping.
1
This guide is under the jurisdiction of ASTM Committee D18 on Soil and
Rockand is the direct responsibility of Subcommittee D18.21 on Groundwater and
2
Vadose Zone Investigations. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved Nov. 1, 2005. Published December 2005. Originally contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
approved in 1994. Discontinued in 2002 and reinstated as D5521–05. Last previous Standards volume information, refer to the standard’s Document Summary page on
e1
edition approved in 1994 as D5521–94 . DOI: 10.1520/D5521-05. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
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