ASTM_D_5126_-_16e1.pdf

Designation:D5126161Standard Guide forComparison of Field Methods for Determining HydraulicConductivity in Vadose Zone1This standard is issued under the fixed designation D5126;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last revision.A number in parentheses indicates the year of last reapproval.Asuperscript epsilon()indicates an editorial change since the last revision or reapproval.1NOTEThe designation was editorially corrected to match the units of measurement statement in October 2016.1.Scope*1.1 This guide covers a review of the test methods fordetermining hydraulic conductivity in unsaturated soils andsediments.Test methods for determining both field-saturatedand unsaturated hydraulic conductivity are described.1.2 Measurement of hydraulic conductivity in the field isused for estimating the rate of water movement through clayliners to determine if they are a barrier to water flux,forcharacterizing water movement below waste disposal sites topredict contaminant movement,and to measure infiltration anddrainage in soils and sediment for a variety of applications.Test methods are needed for measuring hydraulic conductivityranging from 1 102to 1 108cm/s,for both surface andsubsurface layers,and for both field-saturated and unsaturatedflow.1.3 For these field test methods a distinction is madebetween“saturated”(Ks)and“field-saturated”(Kfs)hydraulicconductivity.True saturated conditions seldom occur in thevadose zone except where impermeable layers result in thepresence of perched water tables.During infiltration events orin the event of a leak from a lined pond,a“field-saturated”condition develops.True saturation does not occur due toentrapped air(1).2The entrapped air prevents water frommoving in air-filled pores that,in turn,may reduce thehydraulic conductivity measured in the field by as much as afactor of two compared to conditions when trapped air is notpresent(2).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-ringinfiltrometer test methods,air-entry permeameter test methods,and borehole permeameter tests.Many empirical test methodsare used for calculating hydraulic conductivity from dataobtained with each test method.A general description of eachtest method and special characteristics affecting applicability isprovided.1.5 Field test methods used to determine unsaturated hy-draulic conductivity in the field include direct measurementtechniques and various estimation methods.Direct measure-ment techniques for determining unsaturated hydraulic conduc-tivity include the instantaneous profile(IP)test method and thegypsum crust method.Estimation techniques have been devel-oped using borehole permeameter data and using data obtainedfrom desorption curves(a curve relating water content tomatric potential).1.6 The values stated in SI units are to be regarded asstandard.No other units of measurement are included in thisstandard.1.7 All observed and calculated values shall conform to theguidelines for significant digits and rounding established inPractice D6026.1.7.1 The method used to specify how data are collected,calculated,or recorded in this standard is not directly related tothe accuracy to which the data can be applied in design or otheruses,or both.How one applies the results obtained using thisstandard is beyond its scope.1.8 This standard does not purport to address all of thesafety concerns,if any,associated with its use.It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.1.9 This guide offers an organized collection of informationor a series of options and does not recommend a specificcourse of action.This document cannot replace education orexperience and should be used in conjunction with professionaljudgment.Not all aspects of this guide may be applicable in allcircumstances.This ASTM standard is not intended to repre-sent or replace the standard of care by which the adequacy ofa given professional service must be judged,nor should thisdocument be applied without consideration of a projects many1This guide is under the jurisdiction ofASTM Committee D18 on Soil and Rockand is the direct responsibility of Subcommittee D18.21 on Groundwater andVadose Zone Investigations.Current edition approved July 1,2016.Published July 2016.Originally approvedin 1990.Last previous edition approved in 2010 as D512690(2010)1.DOI:10.1520/D5126-16E01.2The boldface numbers in parentheses refer to a list of references at the end ofthe text.*A Summary of Changes section appears at the end of this standardCopyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 unique aspects.The word“Standard”in the title of thisdocument means only tha