ASTM D5912-96e1

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e1
Designation: D 5912 – 96
Standard Test Method for
(Analytical Procedure) Determining Hydraulic Conductivity
of an Unconfined Aquifer by Overdamped Well Response to
Instantaneous Change in Head (Slug)
This standard is issued under the fixed designation D 5912; 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—Note 5 was added editorially in December 1996.
1. Scope 1.5 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
1.1 This test method covers the determination of hydraulic
responsibility of the user of this standard to establish appro-
conductivity from the measurement of inertial force free
priate safety and health practices and determine the applica-
(overdamped) response of a well-aquifer system to a sudden
bility of regulatory limitations prior to use.
change in water level in a well. Inertial force free response of
the water level in a well to a sudden change in water level is
2. Referenced Documents
characterized by recovery to initial water level in an approxi-
2.1 ASTM Standards:
mate exponential manner with negligible inertial effects.
D 653 Terminology Relating to Soil, Rock, and Contained
1.2 The analytical procedure in this test method is used in
Fluids
conjunctionwiththefieldprocedureinTestMethodD 4044for
D 4043 Guide for Selection of Aquifer-Test Methods in
collection of test data.
Determining Hydraulic Properties by Well Techniques
1.3 Limitations—Slug tests are considered to provide an
D 4044 Test Method (Field Procedure) for Instantaneous
estimate of hydraulic conductivity. The determination of stor-
Change in Head (Slug Test) for Determining Hydraulic
age coefficient is not possible with this test method. Because
Properties of Aquifers
the volume of aquifer material tested is small, the values
D 4104 Test Method (Analytical Procedure) for Determin-
obtained are representative of materials very near the open
ing Transmissivity of Nonleaky Confined Aquifers by
portion of the control well.
Overdamped Well Response to Instantaneous Change in
NOTE 1—Slug tests are usually considered to provide estimates of the
Head (Slug Test)
lower limit of the actual hydraulic conductivity of an aquifer because the
test results are so heavily influenced by well efficiency and borehole skin
3. Terminology
effects near the open portion of the well. The portion of the aquifer that is
3.1 Definitions—For definitions of terms used in this test
testedbytheslugtestislimitedtoanareaneartheopenportionofthewell
method, see Terminology D 653.
wheretheaquifermaterialsmayhavebeenalteredduringwellinstallation,
and therefore may significantly effect the test results. In some cases the 3.2 Symbols:Symbols and Dimensions:
data may be misinterpreted and result in a higher estimate of hydraulic
3.2.1 A [nd]—coefficient that is a function of L/r and is
w
conductivity.This is due to the reliance on early time data that is reflective
determined graphically.
of the hydraulic conductivity of the filter pack surrounding the well. This
3.2.2 B [nd]—coefficient that is a function of L/r and is
2 w
effect was discussed by Bouwer. In addition, because of the reliance on
determined graphically.
early time data, in aquifers with medium to high hydraulic conductivity,
3.2.3 C [nd]—coefficient that is a function of L/r and is
w
the early time portion of the curve that is useful for this data analyses is
determined graphically.
too short (for example, <10 s) for accurate measurement; therefore, the
test results begin to greatly underestimate the true hydraulic conductivity. 3.2.4 D [L]—aquifer thickness.
3.2.5 H [L]—distance between static water level and the
1.4 The values stated in SI units are to be regarded as the
base of open interval of the well.
standard.
3.2.6 L [L]—length of well open to aquifer.
3.2.7 rc [L]—inside diameter of the portion of the well
This test method is under the jurisdiction of ASTM Committee D-18 on Soil
casing in which the water level changes.
and Rock and is the direct responsibility of Subcommittee D18.21 on GroundWater
3.2.8 R [L]—effective radius, determined empirically based
e
and Vadose Zone Investigations.
on the geometry of the well, over which y is dissipated.
Current edition approved Feb. 10, 1996. Published June 1996.
Bouwer, H., and Rice, R. C., “A Slug Test for Determining Hydraulic
Conductivity of Unconfined Aquifers with Completely or Partially Penetrating
Wells,” Water Resources Research, Vol 12, No. 3, 1976, pp. 423–428. 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.
D 5912
3.2.9 r [L]—radial distance from well center to original 5.2 Implications of Assumptions:
w
undisturbed aquifer. 5.2.1 The mathematical equations applied ignore inertial
3.2.10 t [T]—time at end point of straight-line portion of effectsandassumethatthewaterlevelreturnstothestaticlevel
f
graph. in an approximate exponential manner.
3.2.11 t [T]—time at beginning of straight-line portion of
5.2.2 The geometric configuration of the well and aquifer
graph. are shown in Fig. 1, that is after Fig. 1 of Bouwer and Rice.
3.2.12 y [L]—head difference at end point of straight-line
5.2.3 For filter-packed wells, Eq 1 applies to cases in which
f
portion of graph. the filter pack remains saturated. If some of the filter pack is
3.2.13 y [L]—head difference at beginning of straight-line
dewatered during testing, r should be replaced by the
c
portion of graph. following:
2 2 0.5
r corrected 5 1 2 n r 1 nr (4)
~ ! @~ ! #
c a w
4. Summary of Test Method
where:
4.1 This test method describes the analytical procedure for
n 5 short-term specific yield of the filter pack,
analyzing data collected following an instantaneous change in
r 5 uncorrected well casing radius, and
head (slug) test in an overdamped well.The field procedures in a
r 5 borehole radius.
w
conducting a slug test are given in Test Method D 4044. The
analytical procedure consists of analyzing the recovery of
NOTE 6—Short term refers to the duration of the slug test.
water level in the well following the change in water level
induced in the well. 6. Procedure
4.2 Solution—The solution given by Bouwer and Rice
6.1 The overall procedure consists of conducting the slug
follows:
test field procedure (see Test Method D 4044) and analysis of
the field data that is addressed in this test method.
r ln R /r 1 y
~ !
c e w 0
K 5 ln (1)
2L yf 6.2 The water level data are corrected so that the difference
~t 2 t
f 0
between the original static water level and the water level
where:
during the test is known. This difference in water level at time
ifD>H
“t” is deno
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