1、Designation: D7953 14Standard Practice forElectrical Leak Location on Exposed Geomembranes Usingthe Arc Testing Method1This standard is issued under the fixed designation D7953; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the y
2、ear 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 practice is a performance-based standard for anelectrical method for locating leaks in exposed geomembrane
3、s.For clarity, this practice uses the term “leak” to mean holes,punctures, tears, knife cuts, seam defects, cracks, and similarbreaches in an installed geomembrane (as defined in 3.2.4).1.2 This practice can be used for geomembranes installed inbasins, ponds, tanks, ore and waste pads, landfill cell
4、s, landfillcaps, canals, and other containment facilities. It is applicablefor geomembranes made of materials such as polyethylene,polypropylene, polyvinyl chloride, chlorosulfonatedpolyethylene, bituminous geomembrane, and any other electri-cally insulating materials. This practice is best applicab
5、le forlocating geomembrane leaks where the proper preparationshave been made during the construction of the facility.1.3 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.1.4 This standard does not purport to address all of thesaf
6、ety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D4439 Terminology for Geosynthe
7、ticsD6747 Guide for Selection of Techniques for ElectricalDetection of Leaks in GeomembranesD7002 Practice for Leak Location on Exposed Geomem-branes Using the Water Puddle SystemD7703 Practice for Electrical Leak Location on ExposedGeomembranes Using the Water Lance System3. Terminology3.1 Definiti
8、ons:3.1.1 For general definitions used in this practice, refer toTerminology D4439.3.2 Definitions of Terms Specific to This Standard:3.2.1 conductive-backed geomembrane, na specialtygeomembrane manufactured using coextrusion technology fea-turing an insulating layer in intimate contact with a condu
9、ctivelayer3.2.2 current, nthe flow of electricity or the flow ofelectric charge.3.2.3 electrical leak location, na method which useselectrical current or electrical potential to locate leaks in ageomembrane.3.2.4 leak, nfor the purposes of this document, a leak isany unintended opening, perforation,
10、 breach, slit, tear,puncture, crack, or seam breach. Significant amounts of liquidsor solids may or may not flow through a leak. Scratches,gouges, dents, or other aberrations that do not completelypenetrate the geomembrane are not considered to be leaks.Types of leaks detected during surveys include
11、 but are notlimited to; burns, circular holes, linear cuts, seam defects, tears,punctures and material defects.3.2.5 leak detection sensitivity, nthe smallest leak that theleak location equipment and survey methodology are capableof detecting under a given set of conditions. The leak detectionsensit
12、ivity specification is usually stated as a diameter of thesmallest leak that can likely be detected.3.2.6 poor contact condition, nfor the purposes of thisdocument, a poor contact condition means that a leak is not inintimate contact with the conductive layer above or underneaththe geomembrane to be
13、 tested. This occurs on a wrinkle orwave, under the overlap flap of a fusion weld, in an area ofliner bridging and in an area where there is a subgradedepression or rut.3.2.7 probe, nfor the purposes of this document, anyconductive rod or conductive brush that is attached to a powersource to initiat
14、e the arc 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 July 1, 2014. Published July 2014. DOI: 10.1520/D795314.2For referenced ASTM standards, visit the ASTM webs
15、ite, 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 State
16、s14. Significance and Use4.1 Geomembranes are used as barriers to prevent liquidsfrom leaking from landfills, ponds, and other containments. Forthis purpose, it is desirable that the geomembrane have as littleleakage as practical.4.2 The liquids may contain contaminants that if releasedcan cause dam
17、age to the environment. Leaking liquids canerode the subgrade, causing further damage. Leakage can resultin product loss or otherwise prevent the installation fromperforming its intended containment purpose.4.3 Geomembranes are often assembled in the field, eitherby unrolling and welding panels of t
18、he geomembrane materialtogether in the field, unfolding flexible geomembranes in thefield, or a combination of both.4.4 Geomembrane leaks can be caused by poor quality ofthe subgrade, poor quality of the material placed on thegeomembrane, accidents, poor workmanship, manufacturingdefects, and carele
19、ssness.4.5 Electrical leak location methods are an effective andproven quality assurance measure to detect and locate leaks.5. Summary of Exposed Geomembrane ElectricalLocation Methods5.1 Principles of the Electrical Leak Location Methods forExposed Geomembranes:5.1.1 The principle of the electrical
20、 leak location methods isto place a voltage across a geomembrane and then locate areaswhere electrical current flows through leaks in the geomem-brane.5.1.2 Currently available methods include the water puddlemethod (Practice D7002), the water lance method (PracticeD7703), and the arc testing method
21、.5.1.3 All of the methods listed in 5.1.2 are effective atlocating leaks in exposed geomembranes. Each method hasspecific site and labor requirements, survey speeds, advantagesand limitations. A professional specializing in the electricalleak location methods can provide guidance on the advantagesan
22、d disadvantages of each method for a specific project (seeGuide D6747).5.1.4 Alternative ASTM Standard Practices for electricalleak location survey methods should be allowed when mutuallyagreeable and warranted by adverse site conditions, clearlytechnical superiority, logistics, or schedule.6. Arc T
23、esting Method6.1 A summary of the method capabilities and limitations ispresented in Table 1.NOTE 1If used, conductive-backed geomembrane must be installedper the manufacturers recommendations in order to allow it to be testedusing all of the available electrical leak location methods. In particular
24、,there must be some means to break the conductive path through the fusionwelds along the entire lengths of the welds, the undersides of adjacentpanels (and patches) should be electrically connected together, and ameans of preventing unwanted grounding at the anchor trenches or otherunwanted earth gr
25、ounds should be provided.6.2 The Principle of the Arc Testing Method:6.2.1 The principle of this electrical leak location method isto introduce a high voltage between a leak detection test probeand the conductive medium underneath the geomembrane. Thearea is then swept with a test probe to locate po
26、ints where thecurrent completes the circuit through a leak.Avisible electricalarc is formed when the current completes the circuit and thecurrent flow is also converted into an alarm (audible, visual orother, which confirms leak detection and location).6.2.2 Fig. 1 shows a wiring diagram of the arc
27、tester, powersupply and test probe for the arc testing electrical leak locationmethod.6.3 Leak Location Surveys of Exposed Geomembrane Usingthe Arc Testing Method:6.3.1 A grid, test lanes or other acceptable system should beused to ensure that the entire area is tested with the test probe.6.3.2 The
28、probe attachment can be different shapes andlengths, depending on the application to be surveyed. The testprobe may be wider than 1 m, but with a longer the probe itmay be more difficult to make good contact with the geomem-brane along its length.6.4 Preparations and Measurement Considerations:6.4.1
29、 Testing must be performed on geomembranes that aregenerally clean and dry. For geomembrane covered by water orsoils, other test procedures, such as described in Guide D6747are used for testing the geomembrane.6.4.2 Proper field preparations and other measures shall beimplemented to ensure an electr
30、ical connection to the conduc-tive material directly below the geomembrane is in place tosuccessfully complete the leak location survey.6.4.3 There shall be a sufficiently conductive material belowthe geomembrane being tested. A properly-prepared subgradetypically will have sufficiently conductivity
31、. Under properTABLE 1 Summary of Arc Testing MethodGeomembranes Bituminous, CSPE, CPE, EIA, fPP, HDPE, LLDPE, LDPE, PVC, VLDPE U applicableConductive-backed Geomembrane U applicable 1Seams All types: welded, tape, adhesive, glued and other U applicable: project specificJunctions At synthetic pipes a
32、nd accessories U applicable: project specificAt grounded conducting structures X not applicableSurvey During construction phase (installation of GM) U applicableAfter installation (exposed) U applicableSlopes U applicable: project specificInsufficiently conductive subgrade X not applicableDuring the
33、 service life (if exposed) U must be generally clean and dryClimate Sunny, temperate, warm U applicableRainy weather X not applicableFrozen conditions U applicableLeaks detected Discrimination between multiple leaks U applicableD7953 142conditions and preparations, geosynthetic clay liners (GCLs)can
34、 be adequate as conductive material. There are some otherconductive layers such as conductive geotextiles and aluminumfoils with successful field experience which can be installedbeneath the geomembrane to facilitate electrical leak survey(that is, on dry subgrades, or as part of a planar drainagege
35、ocomposite).6.4.4 Measures should be taken to perform the leak locationsurvey when geomembrane wrinkles are minimized. Themaximum arc length for the site conditions can be determinedduring equipment calibration. Any hole located on wrinkleswith a height exceeding the maximum arc length will likely n
36、otbe detected. The leak location survey should be conducted atnight or early morning when wrinkles are minimized. Some-times wrinkles can be flattened by personnel walking orstanding on them as the survey progresses.6.4.5 For lining systems comprised of two geomembraneswith only a geonet or geonet g
37、eocomposite between them, tomake the method feasible a sufficiently conductive layer suchas a conductive geotextile, conductive geocomposite, alumi-num foil, or any appropriate conductive material shall beinstalled under the geomembrane or integrated into the geonetgeocomposite. Conductive-backed ge
38、omembrane can also beused as the primary geomembrane to enable the method. SeeGuide D6747.6.4.6 If the test probe gets too close to the edge of thegeomembrane or to grounded objects, the electrical charge canarc to the grounded object or surrounding soil and will cause afalse positive.6.5 Practices
39、for Surveys with the Arc Testing Method:6.5.1 Before beginning a leak survey, the equipment mustbe checked to ensure it is in working order. The power sourceshould have a range of voltage from 6,000 to 30,000 volts. Awider voltage range is acceptable but the maximum practicalvalue is typically 30,00
40、0 volts.6.5.2 Once the equipment has been checked and wiredproperly, the equipment should be adjusted to the appropriatesensitivity level according to the thickness of the geomembranebeing tested.6.5.3 Once the equipment has been checked and wiredproperly, a trial test must be performed. A puncture
41、(deliberatedefect) should be introduced in a test piece of geomembrane.The deliberate defect should be no greater than 1 mm indiameter. The test piece of geomembrane must be of sufficientsize to enable movement of the testing probe at normal testingspeed over the deliberate defect without touching t
42、he edges ofthe test piece.6.5.3.1 Adjust the sensitivity if necessary in order to easilydetect the deliberate defect.6.5.3.2 Ensure the audible alarm sounds when the test probepasses over the deliberate defect. If the alarm does not sound,recheck the connections and retest. If the alarm sounds prior
43、 topassing over the damage, turn the sensitivity down and retestthe area. The sensitivity setting is site specific and will varywith atmospheric and other site conditions.6.5.3.3 At a minimum, the equipment should be checkedbefore testing begins and after any shut down of an hour ormore. In the even
44、t a test reveals the equipment is not workingproperly, the entire area arc tested since the last passing checkof the equipment must be retested to assure it was arc testedwith working equipment.6.5.4 Field testing may be performed by marking a pre-determined grid, or another acceptable method, and p
45、erformingthe survey within that grid at the same speed as the sensitivitytest was performed.6.5.5 The leak location survey shall be conducted usingprocedures whereby the test probe contacts every point on thesurface of the geomembrane being surveyed for leaks -neglecting the edge and other ground ef
46、fects.6.6 Safety:6.6.1 (WarningThe electrical methods used for geomem-brane leak location use high voltage, low current powersupplies, resulting in the potential for electrical shock. Theelectrical methods used for geomembrane leak location shouldbe attempted by only qualified and experienced person
47、nel.Appropriate safety measures must be taken to protect the leaklocation operators as well as other people at the site.)7. Report7.1 The leak location survey report shall contain the follow-ing information:7.1.1 Description of the survey site,7.1.2 Weather conditions,7.1.3 Type and thickness of geo
48、membrane,FIG. 1 Diagram of the Arc Testing MethodD7953 1437.1.4 Liner system layering,7.1.5 Description of the electrical leak location method,7.1.6 Survey methodology,7.1.7 Identification of equipments and operators,7.1.8 Results of sensitivity test,7.1.9 Specific conditions of survey,7.1.10 Locati
49、on, type and size of detected leaks, and7.1.11 Map of the surveyed areas showing the approximatelocations of the leaks.8. Keywords8.1 arc testing method; bare geomembrane survey; damage;electrical leak detection method; electrical leak location; elec-trical leak location method; exposed geomembrane survey;geoelectric leak location; geomembrane; leak detection; leaklocation survey; leak survey; liner integrity survey; sparktesting method; water lance method; water puddle methodASTM International takes no position respecting the validity of any patent rights asserted in con
