Designation:D5126−16´1StandardGuideforComparisonofFieldMethodsforDeterminingHydraulicConductivityinVadoseZone1ThisstandardisissuedunderthefixeddesignationD5126;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginaladoptionor,inthecaseofrevision,theyearoflastrevision.Anumberinparenthesesindicatestheyearoflastreapproval.Asuperscriptepsilon(´)indicatesaneditorialchangesincethelastrevisionorreapproval.ε1NOTE—ThedesignationwaseditoriallycorrectedtomatchtheunitsofmeasurementstatementinOctober2016.1.Scope*1.1Thisguidecoversareviewofthetestmethodsfordetermininghydraulicconductivityinunsaturatedsoilsandsediments.Testmethodsfordeterminingbothfield-saturatedandunsaturatedhydraulicconductivityaredescribed.1.2Measurementofhydraulicconductivityinthefieldisusedforestimatingtherateofwatermovementthroughclaylinerstodetermineiftheyareabarriertowaterflux,forcharacterizingwatermovementbelowwastedisposalsitestopredictcontaminantmovement,andtomeasureinfiltrationanddrainageinsoilsandsedimentforavarietyofapplications.Testmethodsareneededformeasuringhydraulicconductivityrangingfrom1×10−2to1×10−8cm/s,forbothsurfaceandsubsurfacelayers,andforbothfield-saturatedandunsaturatedflow.1.3Forthesefieldtestmethodsadistinctionismadebetween“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-entrypermeametertestmethods,andboreholep...
