1、Designation: D7852 13Standard Practice forUse of an Electrically Conductive Geotextile for LeakLocation Surveys1This standard is issued under the fixed designation D7852; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of
2、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 practice describes standard procedures forusing a conductive geotextile with electrical methods to locat
3、eleaks in exposed geomembranes and geomembranes coveredwith water or earth materials containing moisture.1.2 This standard practice provides guidance for the use ofappropriate conductive geotextile used in leak location surveyon geomembrane. This guide includes all types of conductivegeotextile with
4、 sufficient conductivity for the particular elec-trical leak location method. A conductive geotextile is appli-cable to all types of geoelectric surveys when there is otherwisenot a conductive layer under the geomembrane.1.3 The leak stream itself being adequately conductive. Aconductive geotextile
5、is applicable to all types of geoelectricsurveys when there is otherwise not a conductive layer underthe geomembrane.1.4 This standard practice is intended to ensure that leaklocation surveys can always be performed with a reasonablelevel of certainty. This standard practice provides guidance forthe
6、 use of appropriate conductive geotextile used in leaklocation survey on geomembranes.1.5 Leak location surveys can be used on non-conductivegeomembranes installed in basins, ponds, tanks, ore and wastepads, landfill cells, landfill caps, other containment facilitiesand building applications such as
7、 in parking garages, decks andgreen roofs. The procedures are applicable for geomembranesmade of non conductive materials such as polyethylene,polypropylene, polyvinyl chloride, chlorosulfonatedpolyethylene, bituminous material, and other electrically-insulating materials. Leak location survey invol
8、ving conduc-tive or partially conductive geomembranes are not within thescope of this document.1.6 WarningThe electrical methods used for geomem-brane leak location could use high voltages, resulting in thepotential for electrical shock or electrocution. This hazardmight be increased because operati
9、ons might be conducted inor near water. In particular, a high voltage could exist betweenthe water or earth material and earth ground, or any groundedconductor. These procedures are potentially VERYDANGEROUS, and can result in personal injury or death.Because of the high voltage that could be involv
10、ed, and theshock or electrocution hazard, do not come in electrical contactwith any leak unless the excitation power supply is turned off.The electrical methods used for geomembrane leak locationshould be attempted only by qualified and experienced person-nel. Appropriate safety measures must be tak
11、en to protect theleak location operators as well as other people at the site.1.7 This standard guide does not purport to address all ofthe safety and liability concerns, if any, associated with its use.It is the responsibility of the user of this standard guide toestablish appropriate safety and hea
12、lth practices and deter-mine the applicability 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 GeomembranesD7002 Practice for Leak Location on Exposed Geom
13、em-branes Using the Water Puddle SystemD7007 Practices for Electrical Methods for Locating Leaksin Geomembranes Covered with Water or Earth Materials3. Terminology3.1 For general definitions related to geosynthetics, seeTerminology D44393.2 Definitions:3.2.1 conductive geotextile, na geotextile fabr
14、icated in aplant using conductive materials, in part or in whole, andproviding a sufficient electrical conductivity to perform elec-trical leak location. D70023.2.2 electrical leak location, nany method which useselectrical current or electrical potential to locate leaks. D70021This practice is unde
15、r the jurisdiction of ASTM Committee on Geosyntheticsand is the direct responsibility of Subcommittee D35.10 on Geomembranes.Current edition approved Jan. 15, 2013. Published February 2012. DOI:10.1520/D7852132For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Custom
16、er 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 States13.2.3 leak, nfor the purposes of this
17、document, a leak isany unintended opening, perforation, breach, slit, tear,puncture, crack, or seam breach through which liquid can flow.Scratches, gouges, dents, or other aberrations that do notcompletely penetrate the geomembrane are not considered tobe leaks. Leaks detected during surveys have be
18、en groupedinto five categories: (1) Holesround shaped voids which mayor may not have downward or upward protruding rims, (2)Tearslinear or areal voids with irregular edge borders, (3)Linear cutslinear voids with neat close edges, (4) Seamdefectsarea of separation between sheets, and (5) Burnedthroug
19、h zonesareas where the polymer has been meltedduring the welding process. D70023.2.4 water, nfor the purposes of this document, waterincludes electrolytes and electrically conductive solutions suchas wastewater, brine, leachate, or any other conductive liquid.D70024. Summary of Practice4.1 The princ
20、iple of the electrical leak location method is toplace a voltage across a geomembrane and then locate areaswhere electrical current flows through discontinuities in thegeomembrane and at seams. It requires an electrically conduc-tive layer below the geomembrane.4.2 The electrical leak location surve
21、y can be applied toexposed and covered geomembranes. The various electricalleak location methods are described in Guide D6747. Stan-dards procedures for the relevant leak location methods aredescribed in Practices D7002 and D7007.4.3 Appropriate conductive geotextiles can be used as theconductive me
22、dia that is needed under the geomembrane. Themethods described in Guide D6747 will require various levelsof conductivity of the geotextile, depending on the method, theconductivity of the media on the geomembrane, the thicknessof the material on the geomembrane, the leak detectioncapabilities of the
23、 equipment, the leak location survey param-eters and other factors.For exposed geomembranes, one output of an electricalexcitation power supply is connected to an electrode placed ina water puddle created on top of the geomembrane. Forcovered geomembranes, the most common implementation ofthis metho
24、d is to make dipole measurements using two movingelectrodes spaced a constant distance apart. Pole measurementscan also be made by making potential measurements on theprotective soil cover using one moving electrode referenced toa second distant electrode. In both case, the other output of thepower
25、supply is connected to an electrode clamped to theelectrically conductive geotextile placed under the geomem-brane (Fig. 1).5. Significance and Use5.1 With the increased use of geomembranes as a barriermaterial to restrict liquid migration from one location toanother, a need has been created for sta
26、ndardized tests bywhich the integrity of the installed geomembrane, including theseams, can be evaluated. This practice is intended to meet sucha need whenever the sub-graded soil is non-conductive, or ageomembrane is installed on a non-conductive material.5.2 The use of a suitably-conductive geotex
27、tile installedbetween a non-conductive soil or material and the geomem-brane will permit electrical leak location survey to be con-ducted.5.3 The compatibility of a conductive geotextile and leaklocation equipment shall be assessed for each leak locationtechnique considered (covered or exposed, when
28、 applicable).Arealistic small scale test shall have been conducted by thesupplier of geotextile and / or leak detection equipment todemonstrate their mutual compatibility for a given leak detec-tion technique.FIG. 1 Schematic of leak detection with conducting geotextileD7852 1326. System calibration
29、 and functionality6.1 The conductive geotextile6.1.1 Geotextile installation The geotextile shall be laidflat and smooth so that it is in direct contact with the subgrade.The geotextile shall be free of tension, folds, and wrinkles. Thenumber of seams and overlaps shall be minimized by selectiveorie
30、ntation of geotextile panels, within the limitations ofmaintaining a consistent pattern. Geotextile shall be placedimmediately prior to geomembrane installation to limit damageto the geotextile from equipment, repeated pedestrian trafficand weather.6.1.2 Seaming (sewing) of the geotextileThe electri
31、calconductive geotextile shall be sewn, heat welded or overlappedaccording to the recommendations of the conductive geotextilemanufacturer.6.1.3 Electrical source and connectionsInsulation mustbe secured prior to a survey to prevent pipe penetration, flangebolts, steel drains and batten strips on st
32、ructure to conductelectricity through the liner and mask potential leak paths. Theconductive geotextile must be connected to the power supplyusing clamps or ground sheets/plates and electrically conduct-ing wires installed below the geomembrane. The design,number, and spacing of the clamps, electrod
33、es, or wires neededto connect to the conductive geotextile depends on the con-ductance of the geotextile, the electrical leak location methodbeing used, and other factors. These factors must be consideredto provide sufficient conductance for aIl possible leak points onthe geomembrane being tested.6.
34、1.4 Electrical conductivity calibrationA test of thegeotextile conductivity and leak detection sensitivity for theworst-case points away from the clamps, electrodes, or wiresshould be performed and documented before the textile iscovered by the geomembrane.6.2 The leak location system calibration6.2
35、.1 A realistic test of the leak detection sensitivity shouldbe performed and documented as part of the leak locationsurvey. An actual or artificial leak simulator can be used. Thecorresponding standard practice for the various leak locationsystems can be used to determine the size, construction, use
36、,and operation of the actual or artificial leak simulator for thatsystem.6.2.2 For the water puddle and water lance systems, PracticeD7002 contains relevant details about the use of an artificialleak. An artificial leak consists of a leak placed in a piece ofgeomembrane installed on the conductive g
37、eotextile. The leaklocation equipment and procedures should be demonstrated tobe able to detect the artificial or actual leak.6.2.3 For a soil-covered geomembrane, Practice D7007contains the relevant details about the construction and use ofan artificial leak. The artificial leak is buried in the pr
38、otectivesoil cover at the depth of the geomembrane with an insulatedwire connecting the electrode to the conductive geotextileunder the geomembrane. The leak location equipment andprocedures should be demonstrated to be able to detect theartificial leak under worst-case conditions.7. Report7.1 In ad
39、dition to the reporting required in the ASTMstandard procedure for the electrical leak location methodbeing used, the report should contain the complete identifica-tion of the conductive geotextile installed.8.1 No statement is made about either the precision or biasof this practice since it merely
40、refers to nondestructive methodsthat could be used in determining the integrity of an installedgeomembrane9. Keywords9.1 conductive geotextile; geomembrane; leak detection;electrical leak location systemASTM International takes no position respecting the validity of any patent rights asserted in con
41、nection with any item mentionedin this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any time by the respon
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