1、Designation: D7703 15D7703 16Standard Practice forElectrical Leak Location on Exposed Geomembranes Usingthe Water Lance Method1This standard is issued under the fixed designation D7703; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revisio
2、n, 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 practice is a performance-based standard for an electrical method for locating leaks in exposed ge
3、omembranes. Forclarity, this practice uses the term “leak” to mean holes, punctures, tears, knife cuts, seam defects, cracks, and similar breaches inan installed geomembrane (as defined in 3.2.5).1.2 This practice can be used for geomembranes installed in basins, ponds, tanks, ore and waste pads, la
4、ndfill cells, landfill caps,canals, and other containment facilities. It is applicable for geomembranes made of materials such as polyethylene, polypropylene,polyvinyl chloride, chlorosulfonated polyethylene, bituminous geomembrane, and any other electrically insulating materials. Thispractice is be
5、st applicable for locating geomembrane leaks where the proper preparations have been made during the constructionof the facility.1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.1.4 This standard does not purport to address
6、 all of the safety 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 regulatorylimitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D4439 Terminology f
7、or GeosyntheticsD6747 Guide for Selection of Techniques for Electrical Leak Location of Leaks in GeomembranesD7002 Practice for Electrical Leak Location on Exposed Geomembranes Using the Water Puddle Method1 This practice is under the jurisdiction of ASTM Committee D35 on Geosynthetics and is the di
8、rect responsibility of Subcommittee D35.10 on Geomembranes.Current edition approved Jan. 1, 2015Jan. 1, 2016. Published February 2015January 2016. Originally approved in 2011. Last previous edition approved in 20112015 asD770311.-15. DOI: 10.1520/D770315.10.1520/D7703-16.2 For referencedASTM standar
9、ds, visit theASTM website, www.astm.org, or contactASTM Customer 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
10、 standard an indication of what changes have been made to the 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 b
11、y ASTM is to be considered the official document.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1D7953 Practice for Electrical Leak Location on Exposed Geomembranes Using the Arc Testing Method3. Terminology3.1 Definitions:3.1.1 For g
12、eneral definitions used in this practice, refer to Terminology D4439.3.2 Definitions of Terms Specific to This Standard:3.2.1 artificial leak, nan electrical simulation of a leak in a geomembrane.3.2.2 conductive-backed geomembrane, na speciality geomembrane manufactured using coextrusion technology
13、 featuring aninsulating layer in intimate contact with a conductive layer.3.2.3 current, nthe flow of electricity or the flow of electric charge.3.2.4 electrical leak location, na method which uses electrical current or electrical potential to locate leaks in a geomembrane.3.2.5 leak, nfor the purpo
14、ses of this practice, a leak is any unintended opening, perforation, breach, slit, tear, puncture, crack,or seam breach. Significant amounts of liquids or solids may or may not flow through a leak. Scratches, gouges, dents, or otheraberrations that do not completely penetrate the geomembrane are not
15、 considered to be leaks. Type of leaks detected during surveysinclude, but are not limited to: burns, circular holes, linear cuts, seam defects, tears, punctures, and material defects.3.2.6 leak detection sensitivity, nthe smallest leak that the leak location equipment and survey methodology are cap
16、able ofdetecting under a given set of conditions. The leak detection sensitivity specification is usually stated as a diameter of the smallestleak that can likely be detected.3.2.7 poor contact condition, nfor the purposes of this practice, a poor contact condition means that a leak is not in intima
17、tecontact with the conductive layer above or underneath the geomembrane to be tested. This occurs on a wrinkle or wave, under theoverlap flap of a fusion weld, in an area of liner bridging and in an area where there is a subgrade depression or rut.3.2.8 probe, nfor the purposes of this practice, any
18、 conductive rod that is attached to a power source.3.2.9 water stream, nfor the purposes of this practice, a continuous stream of water between the water lance and thegeomembrane that creates a conduit for current to flow through any leaks.3.2.10 water lance, nfor the purposes of this practice, a pr
19、obe (lance) incorporating one or two electrodes that directs a solidstream of water through a single nozzle mounted at the end.4. Significance and Use4.1 Geomembranes are used as barriers to prevent liquids from leaking from landfills, ponds, and other containments. For thispurpose, it is desirable
20、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 erode thesubgrade, causing further damage. Leakage can result in product loss or otherwise prevent the installation from perfo
21、rming 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, unfolding flexible geomembranes in the field, or a combination of both.4.4 Geomembrane leaks can be caused by poor quality
22、 of the subgrade, poor quality of the material placed on the geomembrane,accidents, poor workmanship, manufacturing defects, and carelessness.4.5 Electrical leak location methods are an effective and proven quality assurance measure to detect and locate leaks.5. Summary of Exposed Geomembrane Electr
23、ical Leak Location Methods5.1 Principles of the Electrical Leak Location Methods for Exposed Geomembranes:5.1.1 The principle of the electrical leak location methods is to place a voltage across a geomembrane and then locate areaswhere electrical current flows through leaks in the geomembrane.5.1.2
24、Currently available methods include the water puddle method (Practice D7002), the arc testing method (Practice D7953),and the water lance method.5.1.3 All of the methods listed in 5.1.2 are effective at locating leaks in exposed geomembranes. Each method has specific siteand labor requirements, surv
25、ey speeds, advantages, and limitations. A professional specializing in the electrical leak locationmethods can provide advice on the advantages and disadvantages of each method for a specific project.5.1.4 Alternative ASTM Standard Practices for electrical leak location survey methods should be allo
26、wed when mutuallyagreeable and warranted by adverse site conditions, clearly technical superiority, logistics, or schedule.6. Water Lance Method6.1 A summary of the method capabilities and limitations is presented in Table 1.6.2 The Principle of the Water Lance Method:D7703 1626.2.1 Fig. 1 shows a d
27、iagram of electrical leak location using the water lance method for exposed geomembranes. One outputof an electrical excitation power supply is connected to an electrode placed in the water reservoir; a pump sends this charged waterto the water lance that jets the water in a solid stream on top of t
28、he geomembrane. The other output of the power supply isconnected to an electrode placed in electrically conductive material under the geomembrane.6.2.2 The water lance method can also be set up with the same configuration as the water puddle method, as shown in Fig. 2,if the detector electronics are
29、 capable of measuring current and converting that to an audible alarm.6.3 Leak Location Surveys of Exposed Geomembrane Using the Water Lance Method:6.3.1 The water lance leak location method usually consists of a single nozzle mounted at the end of a probe (lance) that directsa solid stream of water
30、 onto a geomembrane, and an electronic detector assembly, as shown in Figs. 1 and 2. A pressurized watersource, usually from a reservoir on top of the liner, or from a tank truck isolated from ground parked at higher elevation, isconnected to the water lance using a plastic or rubber hose.6.3.2 Dire
31、ct current power supplies (often a 12 to 36 volt battery or series of batteries) have been used for water lance leaklocation surveys.6.3.3 For leak location surveys of exposed geomembrane, the solid water stream (not a spray) is moved systematically over thegeomembrane area to locate the points wher
32、e the electrical current flow increases as the charged water from the water lancecontacts the oppositely charged conductive media under the geomembrane through a hole.6.3.4 The voltage drop signal between the two electrodes in the water column in the water lance (or the current flow throughthe detec
33、tor electronics) is connected to an electronic detector assembly that converts the electrical signal to an audible signal thatincreases in pitch and amplitude as the leak signal increases.6.3.5 When a leak signal is detected, the location of the leak is then marked or located relative to fixed point
34、s.6.3.6 The leak detection sensitivity can be very good for this technique. Leaks smaller than 1 mm in diameter are routinelyfound, including leaks through seams in the geomembrane.6.4 Preparations and Measurement Considerations:TABLE 1 Summary of Water Lance MethodGeomembranes Bituminous, CSPE, CPE
35、, EIA, fPP, HDPE, LLDPE,LDPE, PVC, VLDPE,U applicableConductive-backed Geomembrane U applicableASeams All types: welded, tape, adhesive, glued, and other U applicable: project specificJunctions At synthetic pipes and accessories U applicable: project specificAt grounded conducting structures X not a
36、pplicableSurvey During construction phase (installation of GM) U applicableAfter installation (exposed) U applicableSlopes U applicable: project specificInsufficiently conductive subgrade X not applicableDuring the service life (if exposed) U project specificClimate Sunny, temperate, warm U applicab
37、leRainy weather X not applicableFrozen conditions X not applicableLeaks detected Discrimination between multiple leaks U applicableA If used, conductive-backed geomembrane must be installed per the manufacturers recommendations in order to allow it to be tested using all of the available electricall
38、eak location methods. In particular, there must be some means to break the conductive path through the fusion welds along the entire lengths of the welds, the undersidesof adjacent panels (and patches) should be electrically connected together, and a means of preventing unwanted grounding at the anc
39、hor trenches or other unwanted earthgrounds should be provided.FIG. 1 Diagram of the Water Lance Method Using Voltage MeasurementD7703 1636.4.1 Proper field preparations and other measures must be implemented to assure an electrical connection to the sufficientlyconductive material directly below th
40、e geomembrane is in place to successfully complete the leak location survey.6.4.2 There shall be a sufficiently conductive material directly below the geomembrane being tested. A properly-preparedsubgrade typically will have sufficiently conductivity. Under proper conditions and preparations, geosyn
41、thetic clay liners (GCLs)can be adequate as conductive material. There are some other conductive layers such as conductive geotextiles and aluminum foilswith successful field experience which can be installed beneath the geomembrane to facilitate electrical leak survey (that is, on drysubgrades, or
42、as part of a planar drainage geocomposite).6.4.3 Measures should be taken to perform the leak location survey when geomembrane wrinkles are minimized. If a hole islocated on a wrinkle, then this poor contact condition may result in an undetected leak. The leak location survey should beconducted at n
43、ight or early morning when wrinkles are minimized. Sometimes wrinkles can be flattened by personnel walking orstanding on them as the survey progresses.6.4.4 Conversely, surveys should not be made in areas with bridging geomembrane. The survey of areas with minor bridgingmight be accomplished when t
44、he geomembrane is warmer.6.4.5 For lining systems comprised of two geomembranes with only a geonet or geonet/geocomposite between them, to makethe method feasible a sufficiently conductive layer such as a conductive geotextile, conductive geocomposite, aluminum foil, orany appropriate conductive mat
45、erial shall be installed under the geomembrane or integrated into the geonet geocomposite.Conductive-backed geomembrane can also be used as the primary geomembrane to enable the method. See Guide D6747.6.4.6 For best results, conductive paths such as metal pipe penetrations, pump grounds, and batten
46、 strips on concrete should beisolated or insulated from the water lance on the geomembrane. These conductive paths conduct electricity and mask nearby leaksfrom detection.6.4.7 The water stream applied to the geomembrane should not be allowed to flow out of the survey area, connecting the waterto th
47、e ground of the power supply. The results in a false positive signal and will compromise survey sensitivity.6.4.8 Depending on specific construction practices and site conditions, other preparations and support may still be needed tosuccessfully perform the leak location survey.6.5 Practices for Sur
48、veys with the Water Lance Method:6.5.1 A realistic test of the leak detection sensitivity shall be performed and documented as part of the leak location survey. Anactual or artificial leak can be used. The leak location equipment and procedures should demonstrate the ability to detect theartificial
49、or actual leak when the water stream is passed over the leak in the geomembrane.6.5.2 Artificial LeakAn artificial leak may consist of the cut end of an insulated solid core or standard wire, with a crosssection no larger than 1.0 mm diameter, IEC 0.75 mm2 or 18 AWG. The other end of the insulated wire shall be connected to aground electrode or an electrode between the geomembranes in a double geomembrane installation. The distance between theartificial leak ground and the return electrode of the excitation power supply shall be greater than 3 m.6.5.3 Actual LeakIf
