1、Designation: D7002 10Standard Practice forLeak Location on Exposed Geomembranes Using the WaterPuddle System1This standard is issued under the fixed designation D7002; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of las
2、t 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, a performance-based standard for electri-cal methods, covers detecting leaks in exposed geomembranes.For c
3、larity, 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 3.2.5).1.2 This practice can be used for geomembranes installed inbasins, ponds, tanks, ore and waste pads, landfill cells, land
4、fillcaps, canals, and other containment facilities. It is applicablefor geomembranes made of materials such as polyethylene,polypropylene, polyvinyl chloride, chlorosulfonated polyethyl-ene, bituminous geomembrane, and any other electricallyinsulating materials. This practice may not be applicable f
5、orlocating geomembrane leaks where the proper preparationshave not 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 Potential Leak Paths in Geomembranes3. Terminology3.1 Definitions: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 artificial leak, nan electr
8、ical simulation of a leak ina geomembrane.3.2.2 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 detect and locateleaks.3.2.4 electrodes, nthe conductive plate that is placed inearth grou
9、nd or in the material under the geomembrane or aconductive structure, such as a copper manifold, that is placedin the water puddle on the geomembrane.3.2.5 leak, nfor the purposes of this document, a leak isany unintended opening, perforation, breach, slit, tear, punc-ture, crack, or seam breach. Si
10、gnificant amounts of liquids orsolids may or may not flow through a leak. Scratches, gouges,dents, or other aberrations that do not completely penetrate thegeomembrane are not considered to be leaks. Leaks detectedduring surveys have been grouped into five categories:3.2.5.1 burned through zonesvoid
11、s created by meltingpolymer during welding.3.2.5.2 holesround shaped voids with downward or up-ward protruding rims.3.2.5.3 linear cutslinear voids with neat close edges.3.2.5.4 seam defectsarea of partial or total separationbetween sheets.3.2.5.5 tearslinear or areal voids with irregular edgeborder
12、s.3.2.6 leak detection sensitivity, nthe smallest leak that theleak location equipment and survey methodology are capableof detecting under a given set of conditions. The leak detectionsensitivity specification is usually stated as a diameter of thesmallest leak that can be reliably detected.1This p
13、ractice 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, 2010. Published September 2010. Originallyapproved in 2003. Last previous edition approved in 2003 as D700203. DOI:10.152
14、0/D7002-10.2For 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.1Copyright ASTM International, 100 Barr Harbor Dri
15、ve, PO Box C700, West Conshohocken, PA 19428-2959, United States.3.2.7 squeegee, nfor the purposes of this document, asqueegee is a device used to contain and push water on top ofan exposed geomembrane. It may consist of a handle and atransverse piece at one end set with a strip of leather or rubber
16、.3.2.8 water puddle, na small pool of water placed on thegeomembrane to create a conduit for current to flow throughany leaks.4. Summary of Practice4.1 Principle of Electrical Leak Location Method Using theWater Puddle System:4.1.1 The principle of the electrical leak location method isto place a vo
17、ltage across a geomembrane and then locate areaswhere electrical current flows through discontinuities in thegeomembrane and at seams.4.1.2 Fig. 1 shows a diagram of the electrical leak locationmethod of the water puddle system for exposed geomem-branes. One output of an electrical excitation power
18、supply isconnected to an electrode placed in a water puddle created ontop of the geomembrane. The other output of the power supplyis connected to an electrode placed in electrically conductivematerial under the geomembrane.4.1.3 Measurements are made using an electrical currentmeasurement system, th
19、e magnitude of the current beingrelated to the size of the leak.An electronic assembly is usuallyused to produce an audio tone whose frequency is proportionalto the current flow.4.2 Leak Location Surveys of Exposed Geomembrane Usingthe Water Puddle System:4.2.1 The water puddle detection system usua
20、lly consists ofa horizontal water spray manifold with multiple nozzles thatspray water onto a geomembrane, a squeegee device to pushthe resultant puddle of water, and a handle assembly as shownin Fig. 2. A pressurized water source, usually from a tank truckparked at higher elevation, is connected to
21、 the spray manifoldusing a plastic or rubber hose. Figs. 3 and 4 show one exampleof such an apparatus.4.2.2 Direct current power supplies (usually a 12 or 24 voltbattery) have been used for leak location surveys. An alternat-ing current (output requirement of 12 to 30 volt ac) could beused.4.2.3 For
22、 leak location surveys of exposed geomembrane,the water puddle created is pushed systematically over thegeomembrane area to locate the points where the electricalcurrent flow increases.4.2.4 The signal from the probe is typically connected to anelectronic detector assembly that converts the electric
23、al signalto a detector and an audible signal that increases in pitch andamplitude as the leak signal increases.4.2.5 When a leak signal is detected, the location of the leakis then marked or measured relative to fixed points.4.2.6 The leak detection sensitivity can be very good for thistechnique. Le
24、aks smaller than 1 mm in diameter are routinelyfound, including leaks through seams in the geomembrane.4.2.7 The survey rate depends primarily on the manifoldand squeegee width and the presence of wrinkles and waves inthe geomembrane.4.3 Preparations and Measurement Considerations:4.3.1 Proper field
25、 preparations and other measures shall beimplemented to ensure an electrical connection to the conduc-tive material directly below the geomembrane is in place tosuccessfully complete the leak location survey.4.3.2 There shall be a conductive material below thegeomembrane being tested. Leak location
26、survey of geomem-brane have been conducted with a conductivity of a subgradeequivalent to sand with moisture greater than 0.7 % (byweight). A properly-prepared subgrade typically will haveFIG. 1 Diagram of the Electrical Leak Location Method for Surveys with Water Puddle on Exposed GeomembraneD7002
27、102sufficiently conductivity. Under proper conditions and prepa-rations, geosynthetic clay liners (GCLs) can be adequate asconductive material. There are some conductive geotextileswith successful field experience which can be installed beneaththe geomembrane to facilitate electrical leak survey (th
28、at is, ondry subgrades, or as part of a planar drainage geocomposite).4.3.3 Measures should be taken to perform the leak locationsurvey when geomembrane wrinkles are minimized.NOTE 1The leak location survey should be conducted at night or earlymorning when wrinkles are minimized. Sometimes wrinkles
29、can beflattened by personnel walking or standing on them as the surveyprogresses.4.3.4 For lining systems comprised of two geomembraneswith only a geonet or geonet geocomposite between them, tomake the method feasible a conductive layer such as aconductive geotextile shall be installed under the geo
30、mem-brane or integrated into the geonet geocomposite.4.3.5 For best results, conductive paths such as metal pipepenetrations, pump grounds, and batten strips on concreteshould be isolated or insulated from the water puddle on thegeomembrane. These conductive paths conduct electricity andmask nearby
31、leaks from detection. See also Guide D6747.4.3.6 Depending on specific construction practices and siteconditions, other preparations and support may still be neededto successfully perform the leak location survey.4.3.7 The system specifications are presented in Table 1.5. Significance and Use5.1 Geo
32、membranes 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.5.2 The liquids may contain contaminants that if releasedcan cause damage to the environment. Leaking
33、liquids canFIG. 2 Diagram of Electrical Leak Water Puddle SystemFIG. 3 Photograph of a Water Puddle Leak Location EquipmentD7002 103erode the subgrade, causing further damage. Leakage can resultin product loss or otherwise prevent the installation fromperforming its intended containment purpose.5.3
34、Geomembranes are often assembled in the field, eitherby unrolling and welding panels of the geomembrane materialtogether in the field, or unfolding flexible geomembranes in thefield.5.4 Geomembrane leaks can be caused by poor quality ofthe subgrade, poor quality of the material placed on thegeomembr
35、ane, accidents, poor workmanship, and carelessness.5.5 Electrical leak location methods are an effective andproven quality assurance measure to locate previously unde-tected or missed leaks and check the integrity of a liner.6. Practices for Surveys with Water Puddle System6.1 A realistic test of th
36、e leak detection sensitivity shall beperformed and documented as part of the leak location survey.An actual or artificial leak can be used. The leak locationequipment and procedures should be demonstrated to be able todetect the artificial or actual leak when water puddle is passedover the leak on t
37、he geomembrane.6.2 Artificial LeakIf an artificial leak is used, it shall beconstructed by drillinga1mmdiameter hole in approximatelythe center of a piece of geomembrane. The piece of geomem-brane should have a width of at least twice the width of thesqueegee, and a length of at least four times the
38、 width of thesqueegee. The hole should be drilled, and the drill bit recipro-cated in the hole so the geomembrane material is removedrather than displaced. The artificial leak shall be placed on asubgrade that is prepared to be the same as the subgrade underthe actual geomembrane. When surveying lea
39、k detection onexisting containment facilities, a geomembrane sample equiva-lent to the liner installed should be used.6.3 Actual LeakIf an actual leak is used, it shall beconstructed by drillinga1mmdiameter hole in the installedgeomembrane that is to be tested. For double geomembranes,measures shall
40、 be taken to ensure that the secondary geomem-brane is not damaged. The hole shall be drilled at least 600 mmaway from the edge of the geomembrane. The hole should bedrilled, and the drill bit reciprocated in the hole so thegeomembrane material is removed rather than displaced.6.4 The excitation pow
41、er supply and the water supply shallbe turned on, and the water puddle detection system shall bepushed over the artificial or actual leak at a speed equal to thedesired production survey speed.6.5 If the resultant signal is at least 10 percent of the fullscale reading of the detector electronics, th
42、e leak detectionequipment and procedures shall be considered to be success-fully demonstrated.6.6 The leak location survey shall be conducted using thesame water puddle detection system speed as that used for thecalibration.6.7 Periodic testing of the integrity of the electrical circuit isrecommende
43、d. It is recommended to check every 15 to 20 minthe integrity of electrical circuit by contacting (touching) thesubgrade with the equipment squeegee unit or by using an extraelectrical cable well-connected to the subgrade.At a minimum,this check shall be conducted at the beginning and end of eachday
44、 of survey. If the equipment fails to pass the leak detectionsensitivity test, then the area surveyed with that set of equip-ment in the period since the previous leak detection sensitivitytest shall be repeated.7. Report7.1 The leak location survey report shall contain the follow-ing information:7.
45、1.1 Description of the survey site,7.1.2 Climatic conditions,7.1.3 Type and thickness of geomembrane,7.1.4 Liner system layering,7.1.5 Description of the leak location method,7.1.6 Survey methodology,7.1.7 Identification of equipments and operators,7.1.8 Results of artificial or actual leak test,7.1
46、.9 Specific conditions of survey,7.1.10 Location, type and size of detected leaks, and7.1.11 Map of the surveyed areas showing the approximatelocations of the leaks.8. Keywords8.1 electrical leak location method; geomembrane; leakdetectionFIG. 4 Photograph of Leak Location EquipmentD7002 104ASTM Int
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