ASTM D5855-95(2013)
(Test Method)Standard Test Method for (Analytical Procedure) for Determining Transmissivity and Storage Coefficient of Confined Nonleaky or Leaky Aquifer by Constant Drawdown Method in Flowing Well
Standard Test Method for (Analytical Procedure) for Determining Transmissivity and Storage Coefficient of Confined Nonleaky or Leaky Aquifer by Constant Drawdown Method in Flowing Well
SIGNIFICANCE AND USE
5.1 Assumptions—Leaky Aquifer:
5.1.1 Drawdown (sW) in the control well is constant,
5.1.2 Well is infinitesimal diameter and fully penetrates aquifer,
5.1.3 The aquifer is homogeneous, isotropic, and areally extensive, and
5.1.4 The control well is 100 % efficient.
5.2 Assumptions—Nonleaky Aquifer:
5.2.1 Drawdown (sW) in the control well is constant,
5.2.2 Well is infinitesimal diameter and fully penetrates aquifer,
5.2.3 The aquifer is homogeneous, isotropic, and areally extensive,
5.2.4 Discharge from the well is derived exclusively from storage in the nonleaky aquifer, and
5.2.5 The control well is 100 % efficient.
5.3 Implications of Assumptions:
5.3.1 The assumptions are applicable to confined aquifers and fully penetrating control wells. However, this test method may be applied to partially penetrating wells where the method may provide an estimate of hydraulic conductivity for the aquifer adjacent to the open interval of the well if the horizontal hydraulic conductivity is significantly greater than the vertical hydraulic conductivity.
5.3.2 Values obtained for storage coefficient are less reliable than the values calculated for transmissivity. Storage coefficient values calculated from control well data are not reliable.
SCOPE
1.1 This test method covers an analytical solution for determining transmissivity and storage coefficient of a leaky or nonleaky confined aquifer. It is used to analyze data on the flow rate from a control well while a constant head is maintained in the well.
1.2 This analytical procedure is used in conjunction with the field procedure in Practice D5786.
1.3 Limitations—The limitations of this technique for the determination of hydraulic properties of aquifers are primarily related to the correspondence between field situation and the simplifying assumption of the solution.
1.4 Units—The values stated in either SI Units or inch-pound units are to be regarded separately as standard. The values in each system may not be exact equivalents; therefore each system shall be used independently of the other. Combining values from the two systems may result in non-conformance with the standard. Reporting of test results in units other than SI shall not be regarded as nonconformance with this test method.
1.5 All observed and calculated values shall conform to the guidelines for significant digits and rounding established in Practice D6026.
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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Standards Content (Sample)
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Designation:D5855 −95(Reapproved 2013)
Standard Test Method for
(Analytical Procedure) for Determining Transmissivity and
Storage Coefficient of Confined Nonleaky or Leaky Aquifer
by Constant Drawdown Method in Flowing Well
This standard is issued under the fixed designation D5855; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope* 2. Referenced Documents
1.1 This test method covers an analytical solution for 2.1 ASTM Standards:
determiningtransmissivityandstoragecoefficientofaleakyor D653Terminology Relating to Soil, Rock, and Contained
nonleakyconfinedaquifer.Itisusedtoanalyzedataontheflow Fluids
rate from a control well while a constant head is maintained in D4043Guide for Selection of Aquifer Test Method in
the well. Determining Hydraulic Properties by Well Techniques
D5786Practice for (Field Procedure) for Constant Draw-
1.2 Thisanalyticalprocedureisusedinconjunctionwiththe
down Tests in Flowing Wells for Determining Hydraulic
field procedure in Practice D5786.
Properties of Aquifer Systems
1.3 Limitations—The limitations of this technique for the
D6026Practice for Using Significant Digits in Geotechnical
determination of hydraulic properties of aquifers are primarily
Data
related to the correspondence between field situation and the
3. Terminology
simplifying assumption of the solution.
3.1 Definitions:
1.4 Units—The values stated in either SI units or inch-
3.1.1 For definitions of terms used in this test method, see
pound units are to be regarded separately as standard. The
Terminology D653.
values in each system may not be exact equivalents; therefore
3.2 Symbols and Dimensions:
each system shall be used independently of the other. Combin-
2 −1
3.2.1 T—transmissivity [L T ].
ing values from the two systems may result in non-
conformance with the standard. Reporting of test results in
3.2.2 K —modifiedBesselfunctionofthesecondkind,first
units other than SI shall not be regarded as nonconformance
order [nd].
with this test method.
3.2.3 K — modified Bessel function of the second kind,
1.5 All observed and calculated values shall conform to the zero order [nd].
guidelines for significant digits and rounding established in
3.2.4 J — Bessel function of the first kind, zero order [nd].
Practice D6026.
3.2.5 Y — Bessel function of the second kind, zero order
1.6 This standard does not purport to address all of the
[nd].
safety concerns, if any, associated with its use. It is the
3.2.6 W(u)—w (well) function of u [nd].
responsibility of the user of this standard to establish appro-
3.2.7 u—variable of integration [nd].
priate safety and health practices and determine the applica-
bility of regulatory limitations prior to use. 3.2.8 t—elapsed time test [ T].
3 −1
3.2.9 Q—discharge rate [L T ].
3.2.10 s —constant drawdown in control well [L].
1 W
ThistestmethodisunderthejurisdictionofASTMCommitteeD18onSoiland
Rock and is the direct responsibility of Subcommittee D18.21 on Groundwater and
Vadose Zone Investigations. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved March 15, 2013. Published April 2013. Originally contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
approved in 1995. Last previous edition approved in 2006 as D5855–95 (2006). Standards volume information, refer to the standard’s Document Summary page on
DOI: 10.1520/D5855-95R13. the ASTM website.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D5855−95 (2013)
3.2.11 S—storage coefficient [nd]. 4α ` π Y x
2 ~ !
o
2αx 21
G~a! 5 xe 1 tan dx @nd# (8)
* F S DG
ο
π 2 J ~x!
o
3.2.12 r —radius of control well.
W
4.3.1.2 Storage coefficient is given by:
4. Summary of Test Method
Tt
4.1 This test method describes the analytical procedure for
S 5 @nd# (9)
αr
W
analyzing data collected during a constant drawdown aquifer
4.3.2 Semi-Log—The solution is given by Jacob and
test. This test method is usually performed on a flowing well.
Lohman.
After the well has been shut-in for a period of time, the well is
openedandthedischargerateismeasuredoveraperiodoftime
NOTE 4—Jacob and Lohman showed that for all but extremely small
after allowing the well to flow. The water level in the control
values of t, the function of G(a) shown above can be approximated very
wellwhilethewellisflowingistheelevationoftheopeningof closely by 2/ W(u). For sufficiently small values of u, W(u) are further
approximated by 2.30 log 2.25Tt/r S.The use of this semi-logarithmic
the control well through which the water is allowed to flow. 10 W
method will produce values of transmissivity that are slightly elevated.
Data are analyzed by plotting the discharge rate versus time.
Examples of this error are shown below:
NOTE 1—This test method involves the withdrawal of water from a
Estimated
control well that is fully screened through the confined aquifer. The
u W(u) Error, %
withdrawalrateisvariedtocausethewaterlevelwithinthewelltoremain
0.25000 1.044283 25
constant.Thefieldprocedureinvolvedinconductingaconstantdrawdown
0.00625 4.504198 10
test is given in Practice D5786. Methods used to develop a conceptual
0.000833 6.513694 5
model of the site and for initially selecting an analytical procedure are
1.25E-05 10.71258 2
described in Guide D4043.
4.3.2.1 Transmissivity is calculated as follows:
4.2 Leaky Aquifer Solution—The solution is given by Han-
tush. Transmissivity is calculated as follows:
NOTE 5—These equations are Eqs (71) and (73) of Lohman.
2.30
NOTE 2—These are Eq (93) through (97) of Lohman.
2 21
T 5 @L T # (10)
4π∆ s /Q /∆log t/r
~ ! ~ !
W 10 W
Q
2 21
T 5 @L T # (1)
2πs G~α,r /B! by extrapolating the straight line to s /Q =0 (the point of
W W
W
zero drawdown), storage coefficient is given by:
where:
t
Tt
S 5 2.25 T @nd# (11)
α 5 @nd# (2) r
W
Sr
W
NOTE 6—In (Eq 10) and (Eq 11), Q is in cubic feet per day, t is in days.
20.5 2
r /B 5 r T/ K'/b' L (3)
@ ~ !# @ #
W W
5. Significance and Use
and:
5.1 Assumptions—Leaky Aquifer:
r r K r /b r r
~ !
W W 1 w W
5.1.1 Drawdown (s ) in the control well is constant,
G 5 1 exp 2α . (4) W
F G F GF G F S D G
B B K r /b π B
~ !
0 W
5.1.2 Well is infinitesimal diameter and fully penetrates
aquifer,
` uexp~2αu ! du
· nd
* @ # 5.1.3 The aquifer is homogeneous, isotropic, and areally
2 2 2 2
ο J u 1Y u u 1 r /B
~ ! ~ ! ~ !
0 0 W
extensive, and
4.2.1 Storage coefficient is given by:
5.1.4 The control well is 100% efficient.
Tt
5.2 Assumptions—Nonleaky Aquifer:
S 5 nd (5)
@ #
r α
5.2.1 Drawdown (s ) in the control well is constant,
W
W
5.2.2 Well is infinitesimal diameter and fully penetrates
4.3 Non-Leaky Aquifer:
aquifer,
4.3.1 Log-Log—The solution is given by Lohman.
5.2.3 The aquifer is homogeneous, isotropic, and areally
NOTE 3—These equations are Eq (66) through (69) of Lohman.
extensive,
4.3.1.1 Transmissivity is calculated as follows:
5.2.4 Discharge from the well is derived exclusively from
storage in the nonleaky aquifer, and
Q
2 21
T 5 @L T # (6)
5.2.5 The control well is 100% efficient.
2πG α s
~ !
W
5.3 Implications of Assumptions:
where:
5.3.1 The assumptions are applicable to confined aquifers
Tt
and fully penetrating control wells. However, this test method
α 5 nd (7)
@ #
Sr
W maybeappliedtopartiallypenetratingwellswherethemethod
may provide an estimate of hydraulic conductivity for the
and:
aquifer adjacent to the open interval of the well if the
Hantush,M.S.,“NonsteadyFlowtoFlowingWellsinLeakyAquifer,” Journal
of Geophysical Research, Vol 64, No. 8, 1959, pp. 1043–1052. Jacob, C. E., and Lohman, S. W., “Nonsteady Flow to a Well of Constant
Lohman, S. W., “Ground-Water Hydraulics,” Professional Paper 708, U.S. Drawdown in an Extensive Aquifer,” American Geophysical Union Transactions,
Geological Survey, 1972. Vol 33, No. 4, 1952, pp. 552–569.
D5855−95 (2013)
horizontal hydraulic conductivity is significantly greater than 8.1.2.3 Overlay the data plot on the type curve plot and,
the vertical hydraulic conductivity. while the coordinate axes of the two plots are held parallel,
5.3.2 Valuesobtainedforstoragecoefficientarelessreliable shift the data plot to align with the type curve.
than the values calculated for transmissivity. Storage coeffi- 8.1.2.4 Select and record the values of an arbitrary point,
cient values calculated from control well data are not reliable. referred to as the match point, anywhere on the overlapping
part of the plots. Record the values of G(α,r ⁄B), α, Q, and t.
W
6. Apparatus
For convenience the point may be selected where G(α,r ⁄B)
W
and α are integer values.
6.1 Analysis of data from the field
...
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