ASTM D5717-95e1
(Guide)Standard Guide for Design of Ground-Water Monitoring Systems in Karst and Fractured-Rock Aquifers (Withdrawn 2005)
Standard Guide for Design of Ground-Water Monitoring Systems in Karst and Fractured-Rock Aquifers (Withdrawn 2005)
SCOPE
1.1 Justification -This guide considers the characterization of karst and fractured-rock aquifers as an integral component of monitoring-system design. Hence, the development of a conceptual hydrogeologic model that identifies and defines the various components of the flow system is recommended prior to the design and implementation of a monitoring system.
1.2 Methodology and Applicability -This guide is based on recognized methods of monitoring-system design and implementation for the purpose of collecting representative ground-water data. The design guidelines are applicable to the determination of ground-water flow and contaminant transport from existing sites, assessment of proposed sites, and determination of wellhead or springhead protection areas.
1.3 Objectives -The objectives of this guide are to outline procedures for obtaining information on hydrogeologic characteristics and water-quality data representative of karst and fractured-rock aquifers.
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.
WITHDRAWN RATIONALE
This guide considers the characterization of karst and fractured-rock aquifers as an integral component of monitoring-system design.
Formerly under the jurisdiction of ASTM Committee D18 on Soil and Rock, this guide was withdrawn in May 2005 in accordance with section 10.5.3.1 of the Regulations Governing ASTM Technical Committees, which requires that standards shall be updated by the end of the eighth year since the last approval date.
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e1
Designation: D 5717 – 95
Standard Guide for
Design of Ground-Water Monitoring Systems in Karst and
Fractured-Rock Aquifers
This standard is issued under the fixed designation D 5717; 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 1.5 was added editorially October 1998.
INTRODUCTION
This guide for the design of ground-water monitoring systems in karst and fractured-rock aquifers
promotes the design and implementation of accurate and reliable monitoring systems in those settings
where the hydrogeologic characteristics depart significantly from the characteristics of porous media.
Variances from government regulations that require on-site monitoring wells may often be necessary
in karst or fractured-rock terranes (see 7.3) because such settings have hydrogeologic features that
cannotbecharacterizedbytheporous-mediaapproximation.Thisguidewillpromotethedevelopment
of a conceptual hydrogeologic model that supports the need for the variances and aids the designer or
governmental reviewer in establishing the most reliable and efficient monitoring system for such
aquifers.
Many of the approaches contained in this guide may also have value in designing ground-water
monitoring systems in heterogeneous and anisotropic unconsolidated and consolidated granular
aquifers. The focus of this guide, however, is on unconfined karst systems where dissolution has
increased secondary porosity and on other geologic settings where unconfined ground-water flow in
fractures is a significant component of total ground-water flow.
1. Scope acteristics and water-quality data representative of karst and
fractured-rock aquifers.
1.1 Justification—This guide considers the characterization
1.4 This standard does not purport to address all of the
of karst and fractured-rock aquifers as an integral component
safety concerns, if any, associated with its use. It is the
of monitoring-system design. Hence, the development of a
responsibility of the user of this standard to establish appro-
conceptual hydrogeologic model that identifies and defines the
priate safety and health practices and determine the applica-
various components of the flow system is recommended prior
bility of regulatory limitations prior to use.
to the design and implementation of a monitoring system.
1.5 This guide offers an organized collection of information
1.2 Methodology and Applicability—This guide is based on
or a series of options and does not recommend a specific
recognized methods of monitoring-system design and imple-
course of action. This document cannot replace education or
mentation for the purpose of collecting representative ground-
experienceandshouldbeusedinconjunctionwithprofessional
water data. The design guidelines are applicable to the deter-
judgment. Not all aspects of this guide may be applicable in all
mination of ground-water flow and contaminant transport from
circumstances. This ASTM standard is not intended to repre-
existing sites, assessment of proposed sites, and determination
sent or replace the standard of care by which the adequacy of
of wellhead or springhead protection areas.
a given professional service must be judged, nor should this
1.3 Objectives—The objectives of this guide are to outline
document be applied without consideration of a project’s many
procedures for obtaining information on hydrogeologic char-
unique aspects. The word “Standard” in the title of this
document means only that the document has been approved
through the ASTM consensus process.
This guide is under the jurisdiction of ASTM Committee D-18 on Soil and
Rock and is the direct responsibility of Subcommittee D18.21 on GroundWater and
2. Referenced Documents
Vadose Zone Investigations.
Current edition approved April 15, 1995. Published June 1995. 2.1 ASTM Standards:
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D 5717
D 653 Terminology Relating to Soil, Rock, and Contained collapse of a cave roof, or flushing or collapse, or both, of soil
Fluids and other sediment into a subjacent void.
D 5092 Practice for Design and Installation of Ground 3.2.12 slowflow—ground-waterflowwithavelocity<0.001
Water Monitoring Wells in Aquifers m/s.
D 5254 Practice for Minimum Set of Data Elements to 3.2.13 swallet—the hole into which a surface stream sinks.
Identify a Ground-Water Site 3.2.14 tertiary porosity—porosity caused by dissolutional
enlargement of secondary porosity.
3. Terminology
3.2.15 tracer—a substance added to a medium, typically
water, to give it a distinctive signature that makes the medium
3.1 Definitions:
3.1.1 For terms not defined below, see Terminology D 653. recognizable elsewhere.
3.2.16 underflow spring—a spring that is at or near the
3.2 Definitions of Terms Specific to This Standard:
3.2.1 aliasing—the phenomenon in which a high-frequency lowestdischargepointofaground-waterbasinandthatusually
flows perennially (compare with overflow spring).
signal can be interpreted as a low-frequency signal or trend
because the sampling was too infrequent to characterize the
4. Significance and Use
signal.
3.2.2 conduit—pipe-like opening formed and enlarged by 4.1 Users—This guide will be useful to the following
dissolution of bedrock and that has dimensions sufficient to groups of people:
sustain turbulent flow under ordinary hydraulic gradients. 4.1.1 Designers of ground-water monitoring networks who
3.2.3 dissolution zone—a zone where extensive dissolution may or may not have experience in karst or fractured-rock
of bedrock has occurred; void size may range over several terranes;
orders of magnitude. 4.1.2 The experienced ground-water professional who is
3.2.4 epikarst—a zone of enhanced bedrock-dissolution familiar with the hydrology and geomorphology of karst
immediately beneath the soil zone; characterized by storage of terranes but has minimal familiarity with monitoring problems;
water in dissolutionally enlarged fractures and bedding planes, and
and that may be separated from the phreatic zone by a 4.1.3 Regulators who must evaluate existing or proposed
relativelywaterlessintervallocallybreachedbyverticalvadose monitoring for karst or fractured-rock aquifers.
flow. 4.2 Reliable and Effıcient Monitoring Systems—A reliable
3.2.5 fractured-rock aquifer—an aquifer in which flow of and efficient monitoring system provides information relevant
water is primarily through fractures, joints, faults, or bedding to one or more of the following subjects:
planes that have not been significantly enlarged by dissolution. 4.2.1 Geologic and hydrologic properties of an aquifer;
3.2.6 karst aquifer—an aquifer in which all or most flow of 4.2.2 Distribution of hydraulic head in time and space;
water is through one or more of the following: joints, faults, 4.2.3 Ground-water flow directions and rates;
bedding planes, pores, cavities, conduits, and caves, any or all 4.2.4 Water quality with respect to relevant parameters; and
of which have been significantly enlarged by dissolution of 4.2.5 Migration direction, rate, and characteristics of a
bedrock. contaminant release.
3.2.7 karst terrane—a landscape and its subsurface charac- 4.3 Limitations:
terized by flow through dissolutionally modified bedrock and 4.3.1 This guide provides an overview of the methods used
characterized by a variable suite of surface landforms and tocharacterizeandmonitorkarstandfractured-rockaquifers.It
subsurface features, not all of which may be present or does not address the details of these methods, field procedures,
obvious. These include: sinkholes, springs, caves, sinking or interpretation of the data. Numerous references are included
streams, dissolutionally enlarged joints or bedding planes, or for that purpose and are considered an essential part of this
both, and other dissolution features. Most karsts develop in guide. It is recommended that the user of this guide be familiar
limestone or dolomite, or both, but they may also develop in with the relevant material within this guide and the references
gypsum, salt, carbonate-cemented sandstones, and other cited. This guide does not address the application of ground-
soluble rocks. water flow models in the design of monitoring systems in karst
3.2.8 overflow spring—a spring that discharges generally or fractured-rock aquifers. The use of flow and transport mode
intermittently at a ground-water stage above base flow (com- at fractured-rock sites summarized in Ref (1) provide a more
pare with underflow spring). recent comparison of fracturent and transport modeling.
3.2.9 rapid flow—ground-water flow with a velocity >0.001 4.3.2 The approaches to the design of ground-water moni-
m/s. toring systems suggested within this guide are the most
3.2.10 secondary porosity—joints, fissures, faults, that de- appropriate methods for karst and fractured-rock aquifers.
velop after the rock was originally lithified; these features have These methods are commonly used and are widely accepted
not been modified by dissolution. and proven. However, other approaches or methods of ground-
3.2.11 sinkhole—a topographic depression formed as a water monitoring which are technically sound may be substi-
result of karst-related processes such as dissolution of bedrock, tuted if justified and documented.
2 4
Annual Book of ASTM Standards, Vol 04.08. The boldface numbers given in parentheses refer to a list of references at the
Annual Book of ASTM Standards, Vol 04.09. end of the text.
D 5717
5. Special Characteristics of Karst and Fractured-Rock granular aquifer, effective porosity is primarily a consequence
Aquifers of depositional setting, diagenetic processes, texture, and
mineralcompositionwhileinfractured-rockandkarstaquifers,
5.1 Karst and fractured-rock aquifers differ from granular
effective porosity is a secondary result of fractures, faults, and
aquifers in several ways; these differences are outlined in 5.2.
bedding planes. Secondary features modified by dissolution
Designing reliable and efficient monitoring systems requires
comprise tertiary porosity.
the early development of a conceptual hydrogeologic model
5.2.2 Isotropy—Fractured-rock and karst aquifers are typi-
that adequately describes the flow and transmission character-
cally anisotropic in three dimensions. Hydraulic conductivity
istics of the site under investigation. Section 5.3 outlines
canfrequentlyrangeoverseveralordersofmagnitude,depend-
various approaches to conceptualizing these systems and 5.4
ing upon the direction of measurement. Ground water in
contains subjective guidelines for determining which concep-
anisotropic media does not usually move perpendicular to the
tual approach is appropriate for various settings.
hydraulic gradient, but at some angle to it (4 and 5).
5.2 Comparison of Granular, Fractured-Rock, and Karst
Aquifers—Table 1 lists aquifer characteristics and compares
5.2.3 Homogeneity—Thevariationofaquifercharacteristics
the qualitative differences between granular, fractured-rock, within the spatial limits of the aquifer is frequently large in
and karst aquifers. This table represents points along a con-
fractured-rock and karst aquifers. Hydraulic conductivity dif-
tinuum. For this guide a karst aquifer is defined as an aquifer
ferences of several orders of magnitude can occur over very
in which most flow of water is through one or more of the
short horizontal and vertical distances.
following: joints, faults, bedding planes, pores, cavities, con-
5.2.4 Flow—Flow in fractured rocks that are not signifi-
duits, and caves, any or all of which have been significantly
cantly soluble is dependent upon the number of fractures per
enlarged by dissolution of bedrock (2). For this guide a
unit volume, their apertures, their distribution, and their degree
fractured-rockaquiferisdefinedasanaquiferinwhichtheflow
of interconnection. Aquifers with a large number of well-
is primarily through fractures that have not been significantly
connected and uniformly distributed fractures may approxi-
enlarged by dissolution. Fracture is “a general term for any
mate porous media. In these settings, the equations describing
break in rock, whether or not it causes displacement, due to
flow in granular media, based on Darcy’s law, are sometimes
mechanical failure by stress. Fractures include cracks, joints,
applicable. Fractured-rock aquifers that have a few localized
and faults” (3). The following factors must be evaluated to
highly transmissive fractures, or fracture zones that exert a
properly characterize an aquifer’s position in the continuum.
dominant control on ground-water occurrence and movement,
5.2.1 Porosity—The type of porosity is the most important
are not accurately characterized by the porous-media approxi-
difference between these three types of aquifers. All other
mation; they more closely resemble karst aquifers. Ground
differences in characteristics are a function of porosity. In a
water moves through most karst aquifers predominantly
through conduits formed by dissolution and fractures enlarged
by dissolution that occupy a small percentage of the total rock
TABLE 1 Comparison of Granular, Fractured-Rock, and Karst
mass. Ground-water flow in the rock mass is both intergranular
Aquifers (3)
and through fractures that have not been significantly modified
Aquifer Aquifer Type
by dissolution. Such flow is usually only a small percentage of
Characteristics
Granular Fractured Rock Karst
the volume of water discharging from the aquifer, though it
Effective Mostly primary, Mostly Mostly tertiary
provides most of the storage (6).
Porosity through secondary, (secondary porosity
5.2.4.1 It was formerly thought, after the work of Shuster
intergranular through joints, modified by
pores fractures, and dissolution); through
and White (7), that conduit flow was dominant in some
bedding plane pores, bedding
aquifers, and diffuse flow was dominant in others. The
partings planes, fractures,
diffuse-flow dominated regime was thought to be characterized
conduits, and caves
Isotropy More Probably Highly anisotropic
by low variation in hardness, turbidity, and discharge—as
isotropic anisotropic
measuredataspring.Itisnowrecognizedthatthevariationsof
Homogeneity More Less Non-
these parameters are due to the aquifer boundary conditions,
homogeneous homogeneous homogeneous
Flow Slow, laminar Possibly rapid Likely rapid
such as the number of sinking stream inputs or whether the
and possibly and likely turbulent
spring is an underflow or overflow
...
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