Designation:D5126/D5126M−90(Reapproved2010)´1StandardGuideforComparisonofFieldMethodsforDeterminingHydraulicConductivityinVadoseZone1ThisstandardisissuedunderthefixeddesignationD5126/D5126M;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginaladoptionor,inthecaseofrevision,theyearoflastrevision.Anumberinparenthesesindicatestheyearoflastreapproval.Asuperscriptepsilon(´)indicatesaneditorialchangesincethelastrevisionorreapproval.ε1NOTE—Theunitsstatementin1.6andthedesignationwererevisededitoriallyinAugust2010.1.Scope1.1Thisguidecoversareviewofthetestmethodsfordetermininghydraulicconductivityinunsaturatedsoilsandsediments.Testmethodsfordeterminingbothfield-saturatedandunsaturatedhydraulicconductivityaredescribed.1.2Measurementofhydraulicconductivityinthefieldisusedforestimatingtherateofwatermovementthroughclaylinerstodetermineiftheyareabarriertowaterflux,forcharacterizingwatermovementbelowwastedisposalsitestopredictcontaminantmovement,andtomeasureinfiltrationanddrainageinsoilsandsedimentforavarietyofapplications.Testmethodsareneededformeasuringhydraulicconductivityrangingfrom1×10−2to1×10−8cm/s,forbothsurfaceandsubsurfacelayers,andforbothfield-saturatedandunsaturatedflow.1.3Forthesefieldtestmethodsadistinctionmustbemadebetween“saturated”(Ks)and“field-saturated”(Kfs)hydraulicconductivity.Truesaturatedconditionsseldomoccurinthevadosezoneexceptwhereimpermeablelayersresultinthepresenceofperchedwatertables.Duringinfiltrationeventsorintheeventofaleakfromalinedpond,a“field-saturated”conditiondevelops.Truesaturationdoesnotoccurduetoentrappedair(1).2Theentrappedairpreventswaterfrommovinginair-filledporesthat,inturn,mayreducethehydraulicconductivitymeasuredinthefieldbyasmuchasafactoroftwocomparedtoconditionswhentrappedairisnotpresent(2).Fieldtestmethodsshouldsimulatethe“field-saturated”condition.1.4Fieldtestmethodscommonlyusedtodeterminefield-saturatedhydraulicconductivityincludevariousdouble-ringinfiltrometertestmethods,air-entrypermeametertestm...
