ASTM D5912-20
(Practice)Standard Practice for (Analytical Procedure) Determining Hydraulic Conductivity of an Unconfined Aquifer by Overdamped Well Response to Instantaneous Change in Head (Slug)
Standard Practice for (Analytical Procedure) Determining Hydraulic Conductivity of an Unconfined Aquifer by Overdamped Well Response to Instantaneous Change in Head (Slug)
SIGNIFICANCE AND USE
5.1 Assumptions of Solution:
5.1.1 Drawdown (or mounding) of the water table around the well is negligible.
5.1.2 Flow above the water table can be ignored.
5.1.3 Head losses as the water enters or leaves the well are negligible.
5.1.4 The aquifer is homogeneous and isotropic.
Note 6: Slug and pumping tests implicitly assume a porous medium. Fractured rock and carbonate settings may not provide meaningful data and information.
5.2 Implications of Assumptions:
5.2.1 The mathematical equations applied ignore inertial effects and assume that the water level returns to the static level in an approximate exponential manner.
5.2.2 The geometric configuration of the well and aquifer are shown in Fig. 1, that is after Fig. 1 of Bouwer and Rice (1).
Note 7: Short term refers to the duration of the slug test.
Note 8: The function of wells in any unconfined setting in a fractured terrain might make the determination of k problematic because the wells might only intersect tributary or subsidiary channels or conduits. The problems determining the k of a channel or conduit notwithstanding, the partial penetration of tributary channels may make a determination of a meaningful number difficult. If plots of k in carbonates and other fractured settings are made and compared, they may show no indication that there are conduits or channels present, except when with the lowest probability one maybe intersected by a borehole and can be verified, such problems are described by Smart (1999) (6). Additional guidance can be found in Guide D5717.
Note 9: The comparison of data from various methods on variable head permeability tests has been documented. Variation in instrumentation, assumptions and calculational methods will lead to differing results (7). Users should be familiar with the assumptions, instrumentation and calculational aspects of the test when evaluating the results (8).
Note 10: The quality of the result produced by this standard is dependen...
SCOPE
1.1 This practice covers the determination of hydraulic conductivity from the measurement of inertial force free (overdamped) response of a well-aquifer system to a sudden 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 characterized by recovery to initial water level in an approximate exponential manner with negligible inertial effects.
1.2 The analytical procedure in this practice is used in conjunction with the field procedure in Test Method D4044/D4044M for collection of test data.
1.3 Limitations—Slug tests are considered to provide an estimate of hydraulic conductivity. The determination of storage coefficient is not practicable with this practice. Because the volume of aquifer material tested is small, the values obtained are representative of materials very near the open portion of the control well.
Note 1: Slug tests are usually considered to provide estimates of the lower limit of the actual hydraulic conductivity of an aquifer because the test results are so heavily influenced by well efficiency and borehole skin effects near the open portion of the well. The portion of the aquifer that is tested by the slug test is limited to an area near the open portion of the well where the aquifer materials may have been altered during well installation, and therefore may significantly impact the test results. In some cases, the data may be misinterpreted and result in a higher estimate of hydraulic conductivity. This is due to the reliance on early time data that is reflective of the hydraulic conductivity of the filter pack surrounding the well. This effect was discussed by Bouwer (1).2 In addition, because of the reliance on early time data, in aquifers with medium to high hydraulic conductivity, the early time portion of the curve that is useful for this data analyses is too short (for example,
1.4 Units—The values stated in S...
General Information
Relations
Standards Content (Sample)
This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation:D5912 −20
Standard Practice for
(Analytical Procedure) Determining Hydraulic Conductivity
of an Unconfined Aquifer by Overdamped Well Response to
1
Instantaneous Change in Head (Slug)
This standard is issued under the fixed designation D5912; 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* this standard. Reporting of test results in units other than SI
shall not be regarded as nonconformance with this standard.
1.1 This practice covers the determination of hydraulic
conductivity from the measurement of inertial force free
1.5 All observed and calculated values shall conform to the
(overdamped) response of a well-aquifer system to a sudden
guidelines for significant digits and rounding established in
change in water level in a well. Inertial force free response of
Practice D6026.
the water level in a well to a sudden change in water level is
1.5.1 Theproceduresusedtospecifyhowdataarecollected/
characterized by recovery to initial water level in an approxi-
recorded and calculated in the standard are regarded as the
mate exponential manner with negligible inertial effects.
industry standard. In addition, they are representative of the
1.2 The analytical procedure in this practice is used in
significant digits that generally should be retained. The proce-
conjunction with the field procedure in Test Method D4044/
dures used do not consider material variation, purpose for
D4044M for collection of test data.
obtaining the data, special purpose studies, or any consider-
1.3 Limitations—Slug tests are considered to provide an
ations for the user’s objectives; and it is common practice to
estimate of hydraulic conductivity. The determination of stor-
increase or reduce significant digits of reported data to be
agecoefficientisnotpracticablewiththispractice.Becausethe
commensuratewiththeseconsiderations.Itisbeyondthescope
volume of aquifer material tested is small, the values obtained
of these test methods to consider significant digits used in
arerepresentativeofmaterialsveryneartheopenportionofthe
analysis methods for engineering data.
control well.
1.6 This practice offers a set of instructions for performing
NOTE 1—Slug tests are usually considered to provide estimates of the
one or more specific operations. This document cannot replace
lower limit of the actual hydraulic conductivity of an aquifer because the
test results are so heavily influenced by well efficiency and borehole skin
educationorexperienceandshouldbeusedinconjunctionwith
effects near the open portion of the well. The portion of the aquifer that is
professional judgment. Not all aspects of the practice may be
testedbytheslugtestislimitedtoanareaneartheopenportionofthewell
applicable in all circumstances. This ASTM standard is not
wheretheaquifermaterialsmayhavebeenalteredduringwellinstallation,
intended to represent or replace the standard of care by which
and therefore may significantly impact the test results. In some cases, the
data may be misinterpreted and result in a higher estimate of hydraulic
the adequacy of a given professional service must be judged,
conductivity.Thisisduetotherelianceonearlytimedatathatisreflective
nor should this document be applied without the consideration
of the hydraulic conductivity of the filter pack surrounding the well. This
2 ofaproject’smanyuniqueaspects.Theword“Standard”inthe
effect was discussed by Bouwer (1). In addition, because of the reliance
title of this document means only that the document has been
on early time data, in aquifers with medium to high hydraulic
conductivity, the early time portion of the curve that is useful for this data
approved through he ASTM consensus process.
analyses is too short (for example, <10 s) for accurate measurement;
1.7 This standard does not purport to address all of the
therefore, the test results begin to greatly underestimate the true hydraulic
conductivity.
safety concerns, if any, associated with its use. It is the
responsibility of the user of this standard to establish appro-
1.4 Units—The values stated in SI units are to be regarded
as the standard. No other units of measurement are included in priate safety, health, and environmental practices and deter-
mine the applicability of regulatory limitations prior to use.
1
This practice is under the jurisdiction of ASTM Committee D18 on Soil and
1.8 This international standard was developed in accor-
Rock and is the direct responsibility
...
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