ASTM_D_7240_-_06_2011.pdf

Designation:D724006(Reapproved 2011)Standard Practice forLeak Location using Geomembranes with an InsulatingLayer in Intimate Contact with a Conductive Layer viaElectrical Capacitance Technique(ConductiveGeomembrane Spark Test)1This standard is issued under the fixed designation D7240;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.Scope1.1 This standard is a performance-based practice for usingthe spark test to electrically locate leaks in exposed geomem-branes with an insulating layer that are in intimate contact witha conductive layer.For clarity,this document uses the termleak to mean holes,punctures,tears,cuts,cracks and similarbreaches over the partial or entire area of an installed geomem-brane(as defined in 3.2.3).1.2 This test method can be used on exposed geomembranesinstalled in basins,ponds,tanks,ore and waste pads,landfillcells,landfill caps,and other containment facilities.Thisstandard is applicable for geomembranes in direct and intimatecontact with a conductive surface or with a conductive layerintegrally included.1.3 SAFETY WARNING:The electrical methods used forgeomembrane leak location use high voltage,low currentpower supplies,resulting in the potential for electrical shock.The electrical methods used for geomembrane leak locationshould be attempted by only qualified and experienced person-nel.Appropriate safety measures must be taken to protect theleak location operators as well as other people at the site.1.4 This standard does not purport to address all of thesafety and liability concerns,if any,associated with its use.Itis the responsibility of the user of this standard to establishappropriate safety and health practices and determine theapplicability of regulatory limitations prior to use.2.Referenced Documents2.1 ASTM Standards:2D4439 Terminology for GeosyntheticsD6747 Guide for Selection of Techniques for ElectricalDetection of Leaks in Geomembranes3.Terminology3.1 Definition of terms applying to this test method appearin Terminology D4439.3.2 Definitions:3.2.1 electrical leak location,na method which useselectrical current or electrical potential to detect and locateleaks.3.2.2 geomembrane,nan essentially impermeable mem-brane used with foundation,soil,rock,earth or any othergeotechnical engineering related material as an integral part ofa man made project,structure,or system.3.2.3 leak,nFor the purposes of this document,a leak isany unintended opening,perforation,breach,slit,tear,punctureor crack.Significant amounts of liquids or solids may or maynot flow through a leak.Scratches,gouges,dents,or otheraberrations that do not completely penetrate the geomembraneare not considered to be leaks.Leaks detected during surveys have been grouped into threecategories:Holes round shaped voids with downward or upwardprotruding rims Tears linear or circular voids with irregular edge borders Linear cuts linear voids with neat close edges3.2.4 intimate contact,nfor the purposes of thisdocument,intimate contact is when a conductive layer is indirect contact with the insulating geomembrane,and there areno gaps between the two layers to prohibit the flow of current.3.2.5 leak detection sensitivity,nThe smallest size leakthat the leak location equipment and survey methodology arecapable of detecting under a given set of conditions.The leakdetection sensitivity specification is usually stated as a diam-eter of the smallest leak that can be reliably detected.3.2.6 wand,nfor the purposes of this document,any rodthat has a conductive brush that is attached to a power sourceto initiate the spark test.1This practice is under the jurisdiction of ASTM Committee D35 on Geosyn-thetics and is the direct responsibility of Subcommittee D35.10 on Geomembranes.Current edition approved June 1,2011.Published July 2011 Originally publishedin 2006.Last previous edition approved 2006 as D724006.DOI:10.1520/D7240-06R11.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMStandards volume information,refer to the standards Document Summary page onthe ASTM website.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 4.Summary of Practice4.1 The principle of this electrical leak location method is touse a high voltage pulsed power supply to charge a capacitorformed by the underlying conductive layer,the non-conductivelayer of the geomembrane and a coupling pad.The area is thenswept with a test wand to locate points where the capacitordischarges through a leak.Once the system senses the dis-charge current,it is converted into an audible alarm.4.2 General Principles4.2.1 Fig.1 shows a wiring diagram of the coupling pad,power supply and te