ASTM_D_6431_-_18.pdf

Designation:D643118Standard Guide forUsing the Direct Current Resistivity Method for SubsurfaceSite Characterization1This standard is issued under the fixed designation D6431;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.1.Scope*1.1 Purpose and Application:1.1.1 Thisguidesummarizestheequipment,fieldprocedures,and interpretation methods for the assessment ofthe electrical properties of subsurface materials and their porefluids,using the direct current(DC)resistivity method.Mea-surements of the electrical properties of subsurface materialsare made from the land surface and yield an apparent resistiv-ity.These data can then be interpreted to yield an estimate ofthe depth,thickness,voids,and resistivity of subsurfacelayer(s).1.1.2 Resistivity measurements as described in this guideare applied in geological,geotechnical,environmental,andhydrologic investigations.The resistivity method is used tomap geologic features such as lithology,structure,fractures,and stratigraphy;hydrologic features such as depth to watertable,depth to aquitard,and groundwater salinity;and todelineate groundwater contaminants.General references are,Keller and Frischknecht(1),2Zohdy et al(2),Koefoed(3),EPA(4),Ward(5),Griffiths and King(6),and Telford et al(7).1.1.3 This guide does not address the use tomographicinterpretation methods,commonly referred to as electricalresistivity tomography(ERT)or electrical resistivity imaging(ERI).While many of the principles apply the data acquisitionand interpretation differ from those set forth in this guide.1.2 Limitations:1.2.1 This guide provides an overview of the Direct CurrentResistivity Method.It does not address in detail the theory,field procedures,or interpretation of the data.Numerousreferences are included for that purpose and are considered anessential part of this guide.It is recommended that the user ofthe resistivity method be familiar with the references cited inthe text and with the Guide D420,Practice D5088,PracticeD5608,Guide D5730,Test Method G57,D6429,and D6235.1.2.2 This guide is limited to the commonly used approachfor resistivity measurements using sounding and profilingtechniques with the Schlumberger,Wenner,or dipole-dipolearrays and modifications to those arrays.It does not cover theuse of a wide range of specialized arrays.It also does notinclude the use of spontaneous potential(SP)measurements,induced polarization(IP)measurements,or complex resistivitymethods.1.2.3 The resistivity method has been adapted for a numberof special uses,on land,within a borehole,or on water.Discussions of these adaptations of resistivity measurementsare not included in this guide.1.2.4 The approaches suggested in this guide for the resis-tivity method are the most commonly used,widely acceptedand proven;however,other approaches or modifications to theresistivity method that are technically sound may be substitutedif technically justified and documented.1.2.5 This guide offers an organized collection of informa-tion or 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 professionaljudgements.Not all aspects of this guide may be applicable inall circumstances.This ASTM standard is not intended torepresent or replace the standard of care by which theadequacy of a given professional service must be judged,norshould this document be applied without consideration of aprojects many unique aspects.The word“Standard”in thetitle of this document means only that the document has beenapproved through the ASTM consensus process.1.3 UnitsThe values stated in SI units are to be regardedas standard.No other units of measurement are included in thisstandard.Reporting of test results in units other than SI shallnot be regarded as nonconformance with this test method.1.4 Precautions:1.4.1 It is the responsibility of the user of this guide tofollow any precautions in the equipment manufacturers rec-ommendations and to consider the safety implications whenhigh voltages and currents are used.1.4.2 If this guide is used at sites with hazardous materials,operations,or equipment,it is the responsibility of the user ofthis guide to establish appropriate safety and health practicesand to determine the applicability of regulations prior to use.1This guide is under the jurisdiction ofASTM Committee D18 on Soil and Rockand is the direct responsibility of Subcommittee D18.01 on Surface and SubsurfaceCharacterization.Current edition approved Feb.1,2018.Published March 2018.Originallyapproved in 1999.Last previous edition approved in 2010 as D643199(2010).DOI:10.1520/D6431-18.2The boldface numbers in parentheses refer to the list of references at the end ofthis standard.*A Sum