1、Designation: D7007 15D7007 16Standard Practices forElectrical Methods for Locating Leaks in GeomembranesCovered with Water or Earthen Materials1This standard is issued under the fixed designation D7007; the number immediately following the designation indicates the year oforiginal adoption or, in th
2、e case of 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 These practices cover standard procedures for using electrical methods to locate leaks
3、 in geomembranes covered with wateror earthen materials. For clarity, this practice uses the term “leak” to mean holes, punctures, tears, knife cuts, seam defects, cracks,and similar breaches in an installed geomembrane (as defined in 3.2.5).1.2 These practices are intended to ensure that leak locat
4、ion surveys are performed with demonstrated leak detection capability.To allow further innovations, and because various leak location practitioners use a wide variety of procedures and equipment toperform these surveys, performance-based operations are used that specify the minimum leak detection pe
5、rformance for theequipment and procedures.1.3 These practices require that the leak location equipment, procedures, and survey parameters used are demonstrated to resultin an established minimum leak detection distance. The survey shall then be conducted using the demonstrated equipment,procedures,
6、and survey parameters.1.4 Separate procedures are given for leak location surveys for geomembranes covered with water and for geomembranescovered with earthen materials. Separate procedures are given for leak detection distance tests using actual and artificial leaks.1.5 Examples of methods of data
7、analysis for soil-covered surveys are provided as guidance in Appendix X1.1.6 Leak location surveys can be used on geomembranes installed in basins, ponds, tanks, ore and waste pads, landfill cells,landfill caps, and other containment facilities. The procedures are applicable for geomembranes made o
8、f materials such aspolyethylene, polypropylene, polyvinyl chloride, chlorosulfonated polyethylene, bituminous material, and other electrically-insulating materials.1.7 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.1.8 (Warni
9、ngThe electrical methods used for geomembrane leak location could use 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 e
10、arthen material and earth ground, or any grounded conductor. Theseprocedures are potentially VERY DANGEROUS, and can result in personal injury or death. The electrical methods used forgeomembrane leak location should be attempted only by qualified and experienced personnel. Appropriate safety measur
11、es mustbe taken to protect the leak location operators as well as other people at the site.)1.9 This standard does not purport to address 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 pract
12、ices and determine the applicability of regulatorylimitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D4439 Terminology for GeosyntheticsD6747 Guide for Selection of Techniques for Electrical Leak Location of Leaks in Geomembranes1 These practices are under the jurisdiction of ASTM C
13、ommittee D35 on Geosynthetics and is the direct responsibility of Subcommittee D35.10 on Geomembranes.Current edition approved Jan. 1, 2015Jan. 1, 2016. Published February 2015January 2016. Originally approved in 2003. Last previous edition approved in 20092015 asD700709.-15. DOI: 10.1520/D7007-15.1
14、0.1520/D7007-16.2 For referencedASTM standards, 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
15、intended only to provide the user of an ASTM 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 c
16、urrent versionof the standard as published by ASTM is to be considered the official document.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States13. Terminology3.1 For general definitions related to geosynthetics, see Terminology D4439.3.2
17、 Definitions of Terms Specific to This Standard:3.2.1 artificial leak, nan electrical simulation of a leak in a geomembrane.3.2.2 current source electrode, nthe electrode that is placed in the water or earthen material above the geomembrane.3.2.3 dipole measurement, nan electrical measurement made o
18、n or in a partially conductive material using two closely-spacedelectrodes.3.2.4 earthen material, nsand, gravel, clay, silt, combinations of these materials, and similar materials with at least minimalmoisture for electrical current conduction.3.2.5 leak, nfor the purposes of these practices, a lea
19、k 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, orother aberrations that do not completely penetrate the geomembrane are not considered to be leaks. Ty
20、pes of leaks detected duringsurveys include, but are not limited to: burns, circular holes, linear cuts, seam defects, tears, punctures, and material defects.3.2.6 leak detection distance, nThe distance that a leak location equipment and survey methodology are capable of detectinga specified leak. T
21、he leak is usually specified as a circular leak with a specified diameter. For surveys with earthen materials onthe geomembrane, the leak detection distance is usually measured from the surface projection of the leak.3.2.7 noise, nthe unwanted part of a measured signal contributed by phenomena other
22、 than the desired signal.3.2.8 pole measurement, nan electrical measurement made on or in a partially conductive material using one measurementelectrode and a remote reference electrode.3.2.9 potential, nelectrical voltage measured relative to a reference point.4. Significance and Use4.1 Geomembrane
23、s are used as impermeable barriers to prevent liquids from leaking from landfills, ponds, and othercontainments. The liquids may contain contaminants that, if released, can cause damage to the environment. Leaking liquids canerode the subgrade, causing further damage. Leakage can result in product l
24、oss or otherwise prevent the installation fromperforming its intended containment purpose. For these reasons, it is desirable that the geomembrane have as little leakage aspractical.4.2 Geomembrane leaks can be caused by poor quality of the subgrade, poor quality of the material placed on the geomem
25、brane,accidents, poor workmanship, manufacturing defects, and carelessness.4.3 The most significant causes of leaks in geomembranes that are covered with only water are related to construction activitiesincluding pumps and equipment placed on the geomembrane, accidental punctures, and punctures caus
26、ed by traffic over rocks ordebris on the geomembrane or in the subgrade.4.4 The most significant cause of leaks in geomembranes covered with earthen materials is construction damage caused bymachinery that occurs while placing the earthen material on the geomembrane. Such damage also can breach addi
27、tional layers ofthe lining system such as geosynthetic clay liners.4.5 Electrical leak location methods are an effective final quality assurance measure to detect and locate leaks.5. Summary of the Electrical Leak Location Methods for Covered Geomembranes5.1 The principle of the electrical leak loca
28、tion method is to place a voltage across a geomembrane and then locate the pointsof anomalous potential distribution where electrical current flows through leaks in the geomembrane. Additional information canbe found in Guide D6747.5.2 General Principles:5.2.1 Figs. 1 and 2 show diagrams of the elec
29、trical leak location method for a geomembrane covered with water and for ageomembrane covered with earthen materials respectively. One output of an electrical excitation power supply is connected to acurrent source electrode placed in the material covering the geomembrane. The other output of the po
30、wer supply is connected toan electrode in contact with electrically conductive material under the geomembrane.5.2.2 When there are leaks, electrical current flows through the leaks, which produces high current density and a localizedanomaly in the voltage potential distribution in the material above
31、 the geomembrane. Electrical measurements are made to locatethose areas of anomalous signal at the leaks.5.2.3 Measurements are made using a dipole or pole measurement configuration. Various types of data acquisition are used,including audio indications of the signal level, manual measurements with
32、manual recording of data, and automated digital dataacquisition.5.2.4 Direct current and alternating current excitation power supplies and potential measurement systems have been used forleak location surveys.D7007 1625.3 Leak Location Surveys of Geomembranes Covered with Water:5.3.1 Leak location s
33、urveys for geomembranes covered with water can be conducted with water on the geomembrane or withwater covering a layer of earthen materials on the geomembrane.5.3.2 For leak location surveys with water on the geomembrane, usually a dipole probe is systematically scanned through thewater covering th
34、e geomembrane to locate the points of anomalous potential distribution. The dipole spacing is typically 0.2 to1 m.5.3.3 Various types of probes can be used to perform the surveys. Some are for when the operator wades in the water; someare for towing the probe back and forth across the geomembrane; a
35、nd some are for raising and lowering along vertical or slopingwalls.5.3.4 The probe is typically connected to an electronic detector assembly that converts the electrical signal from the probe toan audible signal that increases in pitch and amplitude as the leak signal increases.5.3.5 When a leak si
36、gnal is detected, the point with the maximum signal is then determined. This point of maximum signalcorresponds to the location of the leak. The location of the leak is then marked or measured relative to fixed points.5.3.6 The leak detection distance depends on the leak size, the conductivity of th
37、e materials within, above, and below the leak,the electrical homogeneity of the material above the leak, the output level of the excitation power supply, the design of themeasurement probe, the sensitivity of the detector electronics, the distance away from the leak,survey area configuration andisol
38、ation, and the survey procedures. Leaks as small as 1 mm in diameter have been routinely found, including tortuous leaksthrough welds in the geomembrane. Leaks larger than 25 mm in diameter can usually be detected from several metres away.5.3.7 The survey rate depends primarily on the spacing betwee
39、n scans and the depth of the water.Aclose spacing between scansis needed to detect the smallest leaks.5.4 Leak Location Surveys of Geomembranes Covered with Earthen Materials:5.4.1 For leak location surveys with earthen materials covering the geomembrane, point-by-point measurements are made onthe e
40、arthen material using either dipole measurements or pole measurements. Dipole measurements are typically made with aspacing of 0.5 to 3 m. Measurements are typically made along parallel survey lines or on a grid pattern.5.4.2 The survey procedures are conducted by systematically taking measurements
41、of voltage potential in a grid pattern. Leakscan be located during the performance of the voltage measurements, but the voltage data must be collected for post-surveyevaluation. The measurements and positions can be recorded manually or using a digital data acquisition system. Appendix X1details the
42、 two main methods of data analysis and the advantages and disadvantages of each.FIG. 1 Diagram of the Electrical Leak Location Method for Surveys with Water Covering the GeomembraneFIG. 2 Diagram of the Electrical Leak Location Method for Surveys with Earthen Material Covering the GeomembraneD7007 1
43、635.4.3 The data is typically downloaded or manually entered into a computer and plotted. Sometimes data is taken along surveylines and plotted in graphical format. Sometimes data is taken in a grid pattern and plotted in two-dimensional contour, shade ofgray, or color contour plots, or in three-dim
44、ensional representations of the contours. The data plots are examined for characteristicleak signals.5.4.4 The approximate location of the leak signal is determined from the data plots and additional measurements are made onthe earthen material in the vicinity of the detected leak signal to more acc
45、urately determine the position of the leak.5.4.5 The leak detection distance depends on the leak size, the conductivity of the materials within, above, and below the leak,the electrical homogeneity of the material above the leak, the design of the measurement electrodes, the output level of theexcit
46、ation power supply, the sensitivity of the detector electronics, the distance away from the leak, the survey procedures, andsurvey procedures, the survey area configuration and isolation, and the data interpretation methods and expertise. Usually leaksas small as 5 mm in diameter can be located unde
47、r 600 mm of earthen material. Leaks larger than 25 mm in diameter can usuallybe detected from several metres away.5.4.6 The survey rate depends primarily on the spacing between the measurement points, the type of data acquisition, andwhether data interpretation is accomplished in the field. A close
48、spacing between measurement points is needed to adequatelyreplicate the leak signals and to detect smaller leaks.6. General Leak Location Survey Procedures6.1 The following measures shall be taken to optimize the leak location survey:6.1.1 Conductive paths such as metal pipe penetrations, pump groun
49、ds, and batten strips on concrete should be isolated orinsulated from the water or earthen material on the geomembrane whenever practical. These conductive paths conduct electricityand mask nearby leaks from detection, as well as compromising the overall survey quality.6.1.2 In applications where a single geomembrane is covered with earthen materials that overlap the edges of the geomembrane,if practical, measures should be taken to isolate the edges. If earthen materials overlap the edges of the survey area to earth ground,electrical current will flow from the earthen
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