Standard Guide for Comparison of Field Methods for Determining Hydraulic Conductivity in the Vadose Zone

SCOPE
1.1 This guide covers a review of the test methods for determining hydraulic conductivity in unsaturated soils and sediments. Test methods for determining both field-saturated and unsaturated hydraulic conductivity are described.
1.2 Measurement of hydraulic conductivity in the field is used for estimating the rate of water movement through clay liners to determine if they are a barrier to water flux, for characterizing water movement below waste disposal sites to predict contaminant movement, and to measure infiltration and drainage in soils and sediment for a variety of applications. Test methods are needed for measuring hydraulic conductivity ranging from 1 10 2 to 1 108 cm/s, for both surface and subsurface layers, and for both field-saturated and unsaturated flow.
1.3 For these field test methods a distinction must be made between "saturated" (Ks) and "field-saturated" ( Kfs) hydraulic conductivity. True saturated conditions seldom occur in the vadose zone except where impermeable layers result in the presence of perched water tables. During infiltration events or in the event of a leak from a lined pond, a "field-saturated" condition develops. True saturation does not occur due to entrapped air (). The entrapped air prevents water from moving in air-filled pores that, in turn, may reduce the hydraulic conductivity measured in the field by as much as a factor of two compared to conditions when trapped air is not present  (). Field test methods should simulate the "field-saturated" condition.
1.4 Field test methods commonly used to determine field-saturated hydraulic conductivity include various double-ring infiltrometer test methods, air-entry permeameter test methods, and borehole permeameter tests. Many empirical test methods are used for calculating hydraulic conductivity from data obtained with each test method. A general description of each test method and special characteristics affecting applicability is provided.
1.5 Field test methods used to determine unsaturated hydraulic conductivity in the field include direct measurement techniques and various estimation methods. Direct measurement techniques for determining unsaturated hydraulic conductivity include the instantaneous profile (IP) test method and the gypsum crust method. Estimation techniques have been developed using borehole permeameter data and using data obtained from desorption curves (a curve relating water content to matric potential).
1.6 The values stated in SI units are to be regarded as standard.
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.
1.7 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 professional service must be judged, nor should this document be applied without consideration of a project's many unique aspects. The word "Standard" in the title of this document means only that the document has been approved through the ASTM consensus process.

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ASTM D5126-90(2004) - Standard Guide for Comparison of Field Methods for Determining Hydraulic Conductivity in the Vadose Zone
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NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation: D5126 – 90 (Reapproved 2004)
Standard Guide for
Comparison of Field Methods for Determining Hydraulic
1
Conductivity in Vadose Zone
This standard is issued under the fixed designation D5126; 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 obtained with each test method. Ageneral description of each
testmethodandspecialcharacteristicsaffectingapplicabilityis
1.1 This guide covers a review of the test methods for
provided.
determining hydraulic conductivity in unsaturated soils and
1.5 Field test methods used to determine unsaturated hy-
sediments. Test methods for determining both field-saturated
draulic conductivity in the field include direct measurement
and unsaturated hydraulic conductivity are described.
techniques and various estimation methods. Direct measure-
1.2 Measurement of hydraulic conductivity in the field is
menttechniquesfordeterminingunsaturatedhydraulicconduc-
used for estimating the rate of water movement through clay
tivityincludetheinstantaneousprofile(IP)testmethodandthe
liners to determine if they are a barrier to water flux, for
gypsum crust method. Estimation techniques have been devel-
characterizing water movement below waste disposal sites to
opedusingboreholepermeameterdataandusingdataobtained
predictcontaminantmovement,andtomeasureinfiltrationand
from desorption curves (a curve relating water content to
drainage in soils and sediment for a variety of applications.
matric potential).
Test methods are needed for measuring hydraulic conductivity
−2 −8
1.6 The values stated in SI units are to be regarded as
ranging from 1 310 to 1 310 cm/s, for both surface and
standard.
subsurface layers, and for both field-saturated and unsaturated
1.7 This standard does not purport to address all of the
flow.
safety concerns, if any, associated with its use. It is the
1.3 For these field test methods a distinction must be made
responsibility of the user of this standard to establish appro-
between “saturated” (K ) and “field-saturated” (K ) hydraulic
s fs
priate safety and health practices and determine the applica-
conductivity. True saturated conditions seldom occur in the
bility of regulatory limitations prior to use.
vadose zone except where impermeable layers result in the
1.8 This guide offers an organized collection of information
presence of perched water tables. During infiltration events or
or a series of options and does not recommend a specific
in the event of a leak from a lined pond, a “field-saturated”
course of action. This document cannot replace education or
condition develops. True saturation does not occur due to
2 experienceandshouldbeusedinconjunctionwithprofessional
entrapped air (1). The entrapped air prevents water from
judgment. Not all aspects of this guide may be applicable in all
moving in air-filled pores that, in turn, may reduce the
circumstances. This ASTM standard is not intended to repre-
hydraulic conductivity measured in the field by as much as a
sent or replace the standard of care by which the adequacy of
factor of two compared to conditions when trapped air is not
a given professional service must be judged, nor should this
present (2). Field test methods should simulate the “field-
document be applied without consideration of a project’s many
saturated” condition.
unique aspects. The word “Standard” in the title of this
1.4 Field test methods commonly used to determine field-
document means only that the document has been approved
saturated hydraulic conductivity include various double-ring
through the ASTM consensus process.
infiltrometertestmethods,air-entrypermeametertestmethods,
and borehole permeameter tests. Many empirical test methods
2. Referenced Documents
are used for calculating hydraulic conductivity from data
3
2.1 ASTM Standards:
D653 Terminology Relating to Soil, Rock, and Contained
1
Fluids
ThisguideisunderthejurisdictionofASTMCommitteeD18onSoilandRock
and is the direct responsibility of Subcommittee D18.21 on Ground Water and
Vadose Zone Investigations.
CurrenteditionapprovedJuly1,2004.PublishedJuly2004.Originallyapproved
´1 3
in 1990. Last previous edition approved in 1998 as D5126-90 (1998) . DOI: For referenced ASTM standards, visit the ASTM website, www.astm.org, or
10.1520/D5126-90R04. contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
2
The boldface numbers in parentheses refer to a list of references at the end of Standards volume information, refer to the standard’s Document Summary page on
the text. the ASTM website.
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