1、Designation: D6747 12D6747 15Standard Guide forSelection of Techniques for Electrical Detection LeakLocation of Leaks in Geomembranes1This standard is issued under the fixed designation D6747; the number immediately following the designation indicates the year oforiginal adoption or, in the case of
2、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 guide is intended to assist individuals or groups in assessing different options a
3、vailable for locating leaks ininstalled geomembranes using electrical methods. For clarity, this documentguide uses the term leak“leak” to mean holes,punctures, tears, knife cuts, seam defects, cracks, and similar breaches throughin an installed geomembrane.geomembrane (asdefined in 3.2.3).1.2 This
4、guide does not cover systems that are restricted to seam testing only, nor does it cover systems that may detect leaksnon-electrically. It does not cover systems that only detect the presence, but not the location of leaks.1.3 (WarningThe electrical methods used for geomembrane leak location could u
5、se high voltages, resulting in the potentialfor electrical shock or electrocution. This hazard might be increased because operations might be conducted in or near water. Inparticular, a high voltage could exist between the water or earth material and earth ground, or any grounded conductor. Thesepro
6、cedures are potentially very dangerous, and can result in personal injury or death. The electrical methods used for geomembraneleak location should be attempted only by qualified and experienced personnel. Appropriate safety measures must be taken toprotect the leak location operators as well as oth
7、er people at the site.The electrical methods used for geomembrane leak locationcould use high voltages, resulting in the potential for electrical shock or electrocution. This hazard might be increased becauseoperations might be conducted in or near water. In particular, a high voltage could exist be
8、tween the water or earth material andearth ground, or any grounded conductor. These procedures are potentially very dangerous, and can result in personal injury ordeath. The electrical methods used for geomembrane leak location should be attempted only by qualified and experiencedpersonnel. Appropri
9、ate safety measures must be taken to protect the leak location operators as well as other people at the site.)1.4 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.1.5 This standard does not purport to address all of the safety
10、concerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatoryrequirements prior to use.2. Referenced Documents2.1 ASTM Standards:2D4439 Terminology for GeosyntheticsD7
11、002 Practice for Electrical Leak Location on Exposed Geomembranes Using the Water Puddle MethodD7007 Practices for Electrical Methods for Locating Leaks in Geomembranes Covered with Water or EarthEarthen MaterialsD7240 Practice for Leak Location using Geomembranes with an Insulating Layer in Intimat
12、e Contact with a Conductive Layervia Electrical Capacitance Technique (Conductive Geomembrane Spark Test)D7703 Practice for Electrical Leak Location on Exposed Geomembranes Using the Water Lance MethodD7953 Practice for Electrical Leak Location on Exposed Geomembranes Using the Arc Testing Method3.
13、Terminology3.1 For general definitions used in this document, refer to D4439. For general definitions used in this guide, refer toTerminology D4439.1 This guide is under the jurisdiction of ASTM Committee D35 on Geosynthetics and is the direct responsibility of Subcommittee D35.10 on Geomembranes.Cu
14、rrent edition approved Feb. 15, 2012Jan. 1, 2015. Published February 2012January 2015. Originally approved in 2002. Last previous edition approved in 20022012as D674704.12. DOI: 10.1520/D6747-12.10.1520/D6747-15.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Cust
15、omer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to th
16、e previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.Copyright A
17、STM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States13.2 Definitions of Terms Specific to This Standard:3.2.1 conductive-backed geomembrane, na specialty geomembrane manufactured using the coextrusion process with aninsulating layer in intimate conta
18、ct with a conductive layer.3.2.2 electrical leak location, na method which uses electrical current or electrical potential to detect and locate leaks.locateleaks in a geomembrane.3.2.3 leak, nfor the purposes of this document,guide, a leak is any unintended opening, perforation, breach, slit, tear,
19、puncture,crack, or seam breach. Significant amounts of liquids or solids may or may not flow through a leak. Scratches, gouges, dents, orother aberrations that do not completely penetrate the geomembrane are not considered to be leaks. Leaks Types of leaks detectedduring surveys have been grouped in
20、to five categories:include, but are not limited to: burns, circular holes, linear cuts, seamdefects, tears, punctures, and material defects.3.2.2.1 holesround shaped voids with downward or upward protruding rims.3.2.2.2 tearslinear or areal voids with irregular edge borders.3.2.2.3 linear cutslinear
21、 voids with neat close edges.3.2.2.4 seam defectsarea of partial or total separation between sheets.3.2.2.5 burned through zonesvoids created by melting polymer during welding.3.2.4 leak detection sensitivity, nthe smallest leak that the leak location equipment and survey methodology are capable ofd
22、etecting under a given set of conditions. The leak detection sensitivity specification is usually stated as a diameter of the smallestleak that can be likely detected.3.2.5 poor contact condition, nfor the purposes of this guide, a poor contact condition means that a leak is not in intimatecontact w
23、ith the sufficiently conductive layer above or underneath the geomembrane to be tested. This occurs on a wrinkle or wave,under the overlap flap of a fusion weld, in an area of liner bridging and in an area where there is a subgrade depression or rut.4. Significance and Use4.1 Geomembranes are used a
24、s barriers to prevent liquids from leaking from landfills, ponds, and other containments. For thispurpose, it is desirable that the geomembrane have as little leakage as practical.4.2 The liquids may contain contaminants that, if released, can cause damage to the environment. Leaking liquids can ero
25、de thesubgrade, causing further damage. Leakage can result in product loss or otherwise prevent the installation from performing itsintended containment purpose.4.3 Geomembranes are often assembled in the field, either by unrolling and welding panels of the geomembrane materialtogether in the field,
26、 unfolding flexible geomembranes in the field, or a combination of both.4.4 Leaks are typically related to the Geomembrane leaks can be caused by poor quality of the sub-grade material,subgrade,poor quality of the cover material, care in the cover material installation and quality of geomembrane ins
27、tallation.material placedon the geomembrane, accidents, poor workmanship, manufacturing defects and carelessness.4.5 Experience demonstrates that geomembranes can have leaks caused during their installation and placement of material(s)on the geomembrane.4.6 The damage to a geomembrane can be detecte
28、d using electrical leak location systems. Such systemsElectrical leak locationmethods are an effective and proven quality assurance measure to locate leaks. Such methods have been used successfully to locateleaks in electrically-insulating geomembranes such as polyethylene, polypropylene, polyvinyl
29、chloride, chlorosulfonatedpolyethylene and bituminous geomembranes installed in basins, ponds, tanks, ore and waste pads, and landfill cells.4.7 The principle behind these techniques is to place a voltage across a synthetic an electrically insulating geomembrane andthen locate areas where electrical
30、 current flows through discontinuitiesleaks in the geomembrane (as shown schematically in Fig.1). Other electrical leak paths such as prevent pipe penetrations, flange bolts, steel drains, and batten strips on concrete and otherextraneous electrical paths should be electrically isolated or insulated
31、 to prevent masking of leak signals caused by electricalcurrent flowing short-circuiting through those preferential electrical paths. The only electrical paths should be through leaks in thegeomembrane. This electric detection method ofThese electrical detection methods for locating leaks in geomemb
32、ranes can beperformed on exposed geomembranes, on geomembranes covered with water, or on geomembranes covered with an earthenmaterial layer, or both.layer.5. Developed Methods5.1 Electrical leak detection methods were developed in the early 1980s and commercial surveys have been available since1985.
33、5.2 The principal conditions for the successful application of the methods are as follows:5.2.1 There must be sufficiently conductive material above the geomembrane or the geomembrane should be clean and dry(extent depends on method),D6747 1525.2.2 There must be sufficiently conductive material unde
34、rneath the geomembrane,5.2.3 There must be good contact of the material above and below the geomembrane through the leak, and5.2.4 The sufficiently conductive material above and below the geomembrane are to be in contact only through the leaklocations.5.3 The methods can be organized into two catego
35、ries depending on whether the geomembrane is bare or covered with asufficiently conductive material. A short description of each of the methods that can be applied to these geomembrane conditionsis presented in Sections 6 and 7.5.4 Choosing which method is appropriate for a particular application wi
36、ll depend foremost on whether the geomembrane isbare or covered with water or earth. If the geomembrane is bare, multiple methods are effective. Each method has different featuresand limitations and typical leak detection sensitivities, as described in Section 6. If the geomembrane is covered, the m
37、ethodselection will depend on whether the material is covered with water or earth, and whether the method is to be performed as partof construction or as part of a permanent leak monitoring system, as described in Section 7.5.5 For geomembranes that are to be covered with earthen materials, for enha
38、nced leak detection, a bare geomembrane leaksurvey method should be performed before cover material is placed. The survey on the bare geomembrane will detect the smallerleaks caused during the geomembrane installation. Then after the earth material is placed, the dipole method (Practices D7007)can b
39、e used to locate any damage incurred during material placement. If only the dipole method is used, the smallest leaks causedduring liner installation will likely not be detected due to the variable and generally lower sensitivity of the dipole method.5.6 Conductive-backed geomembrane is manufactured
40、 using a coextrusion process with an insulating layer in intimate contactwith a sufficiently conductive layer and can be used to overcome the subgrade conductivity and hole contact limitations of the waterpuddle, water lance, arc testing, and soil-covered dipole leak location methods. If it is used,
41、 the geomembrane should be installedwith the manufacturers recommended specific installation procedures and equipment to enable electrical leak location methods.If the manufacturers specific recommendations are not followed, in most cases false positive signals will be measured along theseams. In so
42、me cases, some of the methods may not work at all. For example, the false positive signals along the seams can drawtoo much current away from the survey area for the dipole method to be effective, and if the water puddle method is used, falsesignals from the seams can mask the signal of a hole near
43、the seam.6. Exposed Geomembrane Methods6.1 Comparison of Methodologies:6.1.1 Currently available methods include the water puddle method (Practice D7002), the water lance method (Practice D7703),the spark testing method (Practice D7240), and the arc testing method (Practice D7953).6.1.2 All of the m
44、ethods listed in 6.1.1 are effective at locating leaks in exposed geomembranes. Each method has specific siteand labor requirements, survey speeds, advantages, limitations, and cost factors. A professional specializing in the electrical leaklocation methods can provide advice on the advantages and d
45、isadvantages of each method for a specific project. Alternatives toa projects specified method should be accepted when warranted by site conditions, logistics, schedule, or economic reasons.6.2 A summary of the comparisons of the exposed geomembrane electrical leak location methods is presented in T
46、able 1.6.3 The Water Puddle MethodThis technique is appropriate to survey a dry uncovered geomembrane placed directly on asufficiently conductive layer below the electrically insulating geomembrane. Practice D7002 is a standard practice describing thewater puddle method. The lower sufficiently condu
47、ctive material is usually the subgrade soil and the upper sufficiently conductiveFIG. 1 Schematic of the Electrical Leak Location Method (Earthen material-CoveredMaterial-Covered Geomembrane System is Shown)D6747 153layer is the water in an applied puddle. One electrode of a low voltage power supply
48、 is placed in contact with the lower sufficientlyconductive material and another electrode is placed in a water puddle maintained by a squeegee or roller bar (as shownschematically in Fig. 2). Water is usually supplied from a tank or other pressurized water source. For this technique to be effective
49、in locating leaks, the water in the puddle or stream must come into contact through the leak with the electrical conducting materialbelow the geomembrane. This completes an electrical circuit and electrical current will flow. Detector electronics are used tomonitor the electrical current. The detector electronics convert a change in the current into a change in an audio tone. This methodcan typically locate leaks as small as 1 mm in diameter and smaller.TABLE 1 Summary of Comparisons of Exposed Geomembrane Leak Location Methods (typical)Geomembrane Type Water Pud
