ASTM D7002-15

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Designation: D7002 − 10 D7002 − 15
Standard Practice for
Electrical Leak Location on Exposed Geomembranes Using
the Water Puddle SystemMethod
This standard is issued under the fixed designation D7002; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope
1.1 This practice, practice is a performance-based standard for electrical methods, covers detectingan electrical method for
locating leaks in exposed geomembranes. 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 This practice can be used for geomembranes installed in basins, ponds, tanks, ore and waste pads, landfill 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. This
practice may not be is best applicable for locating geomembrane leaks where the proper preparations have not been made during
the construction of 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 all of the safety concerns, if any, associated with its use. It is the responsibility
of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory
limitations prior to use.
2. Referenced Documents
2.1 ASTM Standards:
D4439 Terminology for Geosynthetics
D6747 Guide for Selection of Techniques for Electrical Leak Location of Leaks in Geomembranes
D7703 Practice for Electrical Leak Location on Exposed Geomembranes Using the Water Lance Method
This practice is under the jurisdiction of ASTM Committee D35 on Geosynthetics and is the direct responsibility of Subcommittee D35.10 on Geomembranes.
Current edition approved July 1, 2010Jan. 1, 2015. Published September 2010January 2015. Originally approved in 2003. Last previous edition approved in 20032010
as D7002–03.D7002–10. DOI: 10.1520/D7002-10.10.1520/D7002-15.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D7002 − 15
D7953 Practice for Electrical Leak Location on Exposed Geomembranes Using the Arc Testing Method
3. Terminology
3.1 Definitions:
3.1.1 For general definitions used in this practice, refer to Terminology D4439.
3.2 Definitions of Terms Specific to This Standard:
3.2.1 artificial leak, n—an electrical simulation of a leak in a geomembrane.
3.2.2 conductive-backed geomembrane, n—a specialty geomembrane manufactured using coextrusion technology featuring an
insulating layer in intimate contact with a conductive layer.
3.2.3 current, n—the flow of electricity or the flow of electric charge.
3.2.4 electrical leak location, n—a method which uses electrical current or electrical potential to detect and locate leaks.
3.2.4 electrodes, n—the conductive plate that is placed in earth ground or in the material under the geomembrane or a
conductive structure, such as a copper manifold, that is placed in the water puddle on the geomembrane.
3.2.5 leak, n—for the purposes of this document, 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
other aberrations that do not completely penetrate the geomembrane are not considered to be leaks. Leaks Types of leaks detected
during surveys have been grouped into five categories:include, but are not limited to: burns, circular holes, linear cuts, seam
defects, tears, punctures, and material defects.
3.2.5.1 burned through zones—voids created by melting polymer during welding.
3.2.5.2 holes—round shaped voids with downward or upward protruding rims.
3.2.5.3 linear cuts—linear voids with neat close edges.
3.2.5.4 seam defects—area of partial or total separation between sheets.
3.2.5.5 tears—linear or areal voids with irregular edge borders.
3.2.6 leak detection sensitivity, n—the smallest leak that the leak location equipment and survey methodology are capable of
detecting under a given set of conditions. The leak detection sensitivity specification is usually stated as a diameter of the smallest
leak that can likely be reliably detected.
3.2.7 poor contact condition, n—for the purposes of this practice, a poor contact condition means that a leak is not in intimate
contact with the 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.
3.2.8 probe, n—for the purposes of this practice, any conductive structure that is attached to a power source.
3.2.9 squeegee, n—for the purposes of this document, a squeegee is a device used to contain and push water on top of an
exposed geomembrane. It may consist of a handle and a transverse piece at one end set with a strip of leather or rubber.rubber,
or a roller apparatus.
3.2.10 water puddle, n—a small pool of water placed on the geomembrane to create a conduit for current to flow through any
leaks.
4. Summary of Practice
4.1 Principle of Electrical Leak Location Method Using the Water Puddle System:
4.1.1 The principle of the electrical leak location method is to place a voltage across a geomembrane and then locate areas where
electrical current flows through discontinuities in the geomembrane and at seams.
4.1.2 Fig. 1 shows a diagram of the electrical leak location method of the water puddle system for exposed geomembranes. One
output of an electrical excitation power supply is connected to an electrode placed in a water puddle created on top of the
geomembrane. The other output of the power supply is connected to an electrode placed in electrically conductive material under
the geomembrane.
4.1.3 Measurements are made using an electrical current measurement system, the magnitude of the current being related to the
size of the leak. An electronic assembly is usually used to produce an audio tone whose frequency is proportional to the current
flow.
4.2 Leak Location Surveys of Exposed Geomembrane Using the Water Puddle System:
4.2.1 The water puddle detection system usually consists of a horizontal water spray manifold with multiple nozzles that spray
water onto a geomembrane, a squeegee device to push the resultant puddle of water, and a handle assembly as shown in Fig. 2.
A pressurized water source, usually from a tank truck parked at higher elevation, is connected to the spray manifold using a plastic
or rubber hose. Figs. 3 and 4 show one example of such an apparatus.
4.2.2 Direct current power supplies (usually a 12 or 24 volt battery) have been used for leak location surveys. An alternating
current (output requirement of 12 to 30 volt ac) could be used.
D7002 − 15
FIG. 1 Diagram of the Electrical Leak Location Method for Surveys with Water Puddle on Exposed GeomembraneWater Puddle Method
4.2.3 For leak location surveys of exposed geomembrane, the water puddle created is pushed systematically over the
geomembrane area to locate the points where the electrical current flow increases.
4.2.4 The signal from the probe is typically connected to an electronic detector assembly that converts the electrical signal to
a detector and an audible signal that increases in pitch and amplitude as the leak signal increases.
4.2.5 When a leak signal is detected, the location of the leak is then marked or measured relative to fixed points.
4.2.6 The leak detection sensitivity can be very good for this technique. Leaks smaller than 1 mm in diameter are routinely
found, including leaks through seams in the geomembrane.
4.2.7 The survey rate depends primarily on the manifold and squeegee width and the presence of wrinkles and waves in the
geomembrane.
4.3 Preparations and Measurement Considerations:
4.3.1 Proper field preparations and other measures shall be implemented to ensure an electrical connection to the conductive
material directly below the geomembrane is in place to successfully complete the leak location survey.
4.3.2 There shall be a conductive material below the geomembrane being tested. Leak location survey of geomembrane have
been conducted with a conductivity of a subgrade equivalent to sand with moisture greater than 0.7 % (by weight). A
properly-prepared subgrade typically will have sufficiently conductivity. Under proper conditions and preparations, geosynthetic
clay liners (GCLs) can be adequate as conductive material. There are some conductive geotextiles with successful field experience
which can be installed beneath the geomembrane to facilitate electrical leak survey (that is, on dry subgrades, or as part of a planar
drainage geocomposite).
4.3.3 Measures should be taken to perform the leak location survey when geomembrane wrinkles are minimized.
NOTE 1—The leak location survey should be conducted at night or early morning when wrinkles are minimized. Sometimes wrinkles can be flattened
by personnel walking or standing on them as the survey progresses.
4.3.4 For lining systems comprised of two geomembranes with only a geonet or geonet geocomposite between them, to make
the method feasible a conductive layer such as a conductive geotextile shall be installed under the geomembrane or integrated into
the geonet geocomposite.
4.3.5 For best results, conductive paths such as metal pipe penetrations, pump grounds, and batten strips on concrete should be
isolated or insulated from the water puddle on the geomembrane. These conductive paths conduct electricity and mask nearby leaks
from detection. See also Guide D6747.
4.3.6 Depending on specific construction practices and site conditions, other preparations and support may still be needed to
successfully perform the leak location survey.
4.3.7 The system specifications are presented in Table 1.
4. Significance and Use
4.1 Geomembranes are used as barriers to prevent liquids from leaking from landfills, ponds, and other containments. For this
purpose, 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 erode the
subgrade, causing further damage. Leakage can result in product loss or otherwise prevent the installation from performing its
intended containment purpose.
4.3 Geomembranes are often assembled in the field, either by unrolling and welding panels of the geomembrane material
together in the field, unfolding flexible geomembranes in the field, or a combination of both.
D7002 − 15
TABLE 1 Specifications—Water Puddle Leak Detection TechniquesSummary of Water Puddle Method
Geomembranes Bituminous, CSPE, CPE, EIA, fPP, HDPE, LLDPE, LDPE, PVC, VLDPE U applicable
EPDM, GCL X not applicable
Exposed U applicable
Covered X not applicable
A
Conductive-backed Geomembrane U applicable
Characteristics Training time 1 day
Set up time and calibration time 1 to 3 h
Measurement time instantaneous
Leak location time 10 min max
Subgrade moisture (by weight) equivalent to sand with > 0.7 %
Average survey speed (horizontal surface) 500 m per hour per operator
Power supply 12 or 24 volts dc or ac
Seams All types: welded, tape, adhesive, glued and other U applicable: project specific
Seams All types: welded, tape, adhesive, glued and other U applicable: project specific
Junctions At synthetic pipes and accessories U applicable: project specific
Junctions At synthetic pipes and accessories U applicable: project specific
At permanent structure U applicable: project specific
At grounded conducting structures X not applicable
Survey During construction phase (installation of GM) U applicable
After installation (exposed) U applicable
After soil covering X not applicable
Presence of large wrinkles and waves X not applicable
Slopes U applicable: project specific
Desiccated subgrade (conductivity equivalent to sand with < 0.7 % moisture) X not applicable
Insufficiently conductive subgrade X not applicable
During the service life (if exposed) U applicable
During the service life (if exposed) U project specific
Electrical isolated conductive structures U applicable
Climate Sunny, temperate, warm U applicable
Rainy weather, freezing weather X not applicable
Rainy weather X not applicable
Leak detected Size of 1 mm and larger U applicable
Frozen conditions X not applicable
Leaks detected Discrimination between multiple leaks U applicable
A
If used, conductive-backed geomembrane must be installed per the manufacturer’s recommendations in order to allow it to be tested using all of the available electrical
leak 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 undersides
of adjacent panels (and patches) should be electrically connected together, and a means of preventing unwanted grounding at the anchor or other unwanted earth grounds
should be provided.
4.4 Geomembrane leaks can be caused by poor quality 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. Significance and Use
5.1 Geomembranes are used as barriers to prevent liquids from leaking from landfills, ponds, and other containments. For this
purpose, it is desirable that the geomembrane have as little leakage as practical.
5.2 The liquids may contain contaminants that if released can cause damage to the environment. Leaking li
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