ASTM D7240-18

Standard Practice for Electrical Leak Location Using Geomembranes with an Insulating Layer in Intimate Contact with a Conductive Layer via Electrical Capacitance Technique (Conductive-Backed Geomembrane Spark Test)

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 which, 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.  
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.
SCOPE
1.1 This practice is a performance-based standard for an electrical method for locating leaks in exposed conductive-backed 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 3.2.7).  
1.2 This practice can be used for conductive-backed geomembranes installed in basins, ponds, tanks, ore and waste pads, landfill cells, landfill caps, canals, and other containment facilities. It is applicable for conductive-backed geomembranes made of materials such as polyethylene, polypropylene, polyvinyl chloride, chlorosulfonated polyethylene, bituminous geomembrane, and any other electrically insulating materials. This practice is best applicable for locating conductive-backed geomembrane leaks where the proper preparations have been made during the construction of the facility.  
1.3 For electrical leak location of conductive-backed geomembranes using methods in lieu of or in addition to the spark testing method, the installation must be electrically isolated (as defined in 3.2.5).  
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 The spark test may produce an electrical spark and therefore should only be used where an electrical spark would not create a hazard. 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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
1.6 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

General Information

• Status: Published
• Publication Date: 31-Jan-2018
• ICS: 59.080.70 - Geotextiles
• Technical Committee: D35 - Geosynthetics
• Drafting Committee: D35.10 - Geomembranes

Relations

• Replaces: ASTM D7240-06(2011) - Standard Practice for Leak Location using Geomembranes with an Insulating Layer in Intimate Contact with a Conductive Layer via Electrical Capacitance Technique (Conductive Geomembrane Spark Test)
• Effective Date: 01-Feb-2018
• Refers: ASTM D4439-24 - Standard Terminology for Geosynthetics
• Effective Date: 01-Feb-2024
• Refers: ASTM D5820-95(2023) - Standard Practice for Pressurized Air Channel Evaluation of Dual-Seamed Geomembranes
• Effective Date: 01-Nov-2023
• Refers: ASTM D4439-18 - Standard Terminology for Geosynthetics
• Effective Date: 15-Apr-2018
• Refers: ASTM D5820-95(2018) - Standard Practice for Pressurized Air Channel Evaluation of Dual-Seamed Geomembranes
• Effective Date: 01-Feb-2018
• Refers: ASTM D4439-17 - Standard Terminology for Geosynthetics
• Effective Date: 01-Aug-2017
• Refers: ASTM D5641/D5641M-16 - Standard Practice for Geomembrane Seam Evaluation by Vacuum Chamber
• Effective Date: 01-Jul-2016
• Refers: ASTM D4439-15a - Standard Terminology for Geosynthetics
• Effective Date: 01-Sep-2015
• Refers: ASTM D4439-15 - Standard Terminology for Geosynthetics
• Effective Date: 01-Jul-2015
• Refers: ASTM D4439-14 - Standard Terminology for Geosynthetics
• Effective Date: 01-Mar-2014
• Refers: ASTM D6747-12 - Standard Guide for Selection of Techniques for Electrical Detection of Leaks in Geomembranes
• Effective Date: 15-Feb-2012
• Refers: ASTM D4439-11 - Standard Terminology for Geosynthetics
• Effective Date: 01-Oct-2011
• Refers: ASTM D5820-95(2011) - Standard Practice for Pressurized Air Channel Evaluation of Dual Seamed Geomembranes
• Effective Date: 01-Jun-2011
• Refers: ASTM D5820-95(2006) - Standard Practice for Pressurized Air Channel Evaluation of Dual Seamed Geomembranes
• Effective Date: 01-Jun-2006
• Refers: ASTM D6747-04 - Standard Guide for Selection of Techniques for Electrical Detection of Potential Leak Paths in Geomembrane
• Effective Date: 01-Nov-2004

Overview

ASTM D7240-18: Standard Practice for Electrical Leak Location Using Geomembranes with an Insulating Layer in Intimate Contact with a Conductive Layer via Electrical Capacitance Technique (Conductive-Backed Geomembrane Spark Test) establishes procedures for detecting and locating leaks in conductive-backed geomembranes. Primarily used in containment facilities such as landfills, ponds, tanks, and landfill caps, this performance-based standard details the application of electrical spark testing through the capacitance technique to ensure the integrity and functionality of geomembrane barriers.

Geomembranes are critical components in environmental containment, designed to prevent the migration of liquids-which may contain hazardous contaminants-into the surrounding environment. The presence of leaks can erode subgrades, compromise structural integrity, and result in environmental and economic loss. ASTM D7240-18 provides a reliable quality assurance practice for identifying leaks such as punctures, tears, seam defects, and other breaches in installed geomembrane systems.

Key Topics

• Scope and Application: Covers electrical methods (specifically spark testing) for locating leaks in exposed, conductive-backed geomembranes consisting of an insulating geomembrane layer in direct contact with a conductive backing.
• Leak Definition: Includes holes, punctures, tears, knife cuts, seam defects, cracks, and other breaches that compromise geomembrane integrity.
• Testing Conditions:
  • Suitable for geomembranes made of materials such as polyethylene, polypropylene, PVC, and chlorosulfonated polyethylene with a conductive base.
  • Geomembrane surfaces must be clean and dry; alternate methods are required for submerged or soil-covered installations.
• Safety: Emphasizes the use of high-voltage, low-current equipment, requiring qualified personnel and adequate safety measures to prevent electrical hazards.
• Testing Methodology:
  • Use of a high-voltage pulsed power supply and a conductive coupling pad.
  • A test wand is employed to sweep the geomembrane surface; leaks are detected through current discharge, often signaled by an audible alarm.
  • Testing is performed in a systematic grid or lane-based approach to ensure complete area coverage.

Applications

• Landfills: Integrity surveys of geomembrane liners and caps during and after installation to prevent leakage of hazardous waste.
• Ponds and Basins: Verification of containment in industrial, agricultural, and environmental management applications.
• Tanks and Pads: Ensuring secure containment for ore, waste, and chemical storage facilities.
• Canals and Channels: Leak detection for long-term performance and regulatory compliance.
• Construction Quality Assurance (CQA): Used by contractors, engineers, and owners to verify the performance of geomembrane installations before commissioning and throughout service life.
• Regulatory Compliance: Meets requirements for environmental protection agencies and governing bodies seeking robust leak detection and prevention measures.

Related Standards

ASTM D7240-18 references and is complemented by several related ASTM standards for geosynthetics and leak detection:

• ASTM D4439: Terminology for Geosynthetics
• ASTM D5641/D5641M: Practice for Geomembrane Seam Evaluation by Vacuum Chamber
• ASTM D5820: Practice for Pressurized Air Channel Evaluation of Dual Seamed Geomembranes
• ASTM D6747: Guide for Selection of Techniques for Electrical Leak Location of Leaks in Geomembranes

These related documents assist in ensuring the comprehensive evaluation and maintenance of geomembrane systems, bolstering the effectiveness of quality assurance programs within environmental containment applications.

Keywords: ASTM D7240-18, electrical leak location, conductive-backed geomembrane, spark testing, leak detection, geomembrane integrity, environmental containment, quality assurance, leak location survey.

Standards Content (Sample)

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: D7240 − 18
Standard Practice for
Electrical Leak Location Using Geomembranes with an
Insulating Layer in Intimate Contact with a Conductive
Layer via Electrical Capacitance Technique (Conductive-
Backed Geomembrane Spark Test)
This standard is issued under the fixed designation D7240; 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 1.6 This international standard was developed in accor-
dance with internationally recognized principles on standard-
1.1 This practice is a performance-based standard for an
ization established in the Decision on Principles for the
electrical method for locating leaks in exposed conductive-
Development of International Standards, Guides and Recom-
backed geomembranes. For clarity, this practice uses the term
mendations issued by the World Trade Organization Technical
“leak”tomeanholes,punctures,tears,knifecuts,seamdefects,
Barriers to Trade (TBT) Committee.
cracks, and similar breaches in an installed geomembrane (as
defined in 3.2.7).
2. Referenced Documents
1.2 This practice can be used for conductive-backed
2.1 ASTM Standards:
geomembranes installed in basins, ponds, tanks, ore and waste
D4439 Terminology for Geosynthetics
pads, landfill cells, landfill caps, canals, and other containment
D5641/D5641M Practice for Geomembrane Seam Evalua-
facilities.Itisapplicableforconductive-backedgeomembranes
tion by Vacuum Chamber
made of materials such as polyethylene, polypropylene, poly-
D5820 Practice for Pressurized Air Channel Evaluation of
vinyl chloride, chlorosulfonated polyethylene, bituminous
Dual Seamed Geomembranes
geomembrane, and any other electrically insulating materials.
D6747 GuideforSelectionofTechniquesforElectricalLeak
This practice is best applicable for locating conductive-backed
Location of Leaks in Geomembranes
geomembrane leaks where the proper preparations have been
3. Terminology
made during the construction of the facility.
3.1 Definitions:
1.3 For electrical leak location of conductive-backed
3.1.1 For general definitions used in this practice, refer to
geomembranes using methods in lieu of or in addition to the
Terminology D4439.
spark testing method, the installation must be electrically
3.2 Definitions of Terms Specific to This Standard:
isolated (as defined in 3.2.5).
3.2.1 conductive-backed geomembrane, n—a specialty
1.4 The values stated in SI units are to be regarded as
geomembrane manufactured using coextrusion technology,
standard. No other units of measurement are included in this
featuring an insulating layer in intimate contact with a conduc-
standard.
tive layer.
1.5 The spark test may produce an electrical spark and
3.2.2 coupling pad, n—an electrically conductive pad
therefore should only be used where an electrical spark would
placed on top of the geomembrane and connected to the spark
not create a hazard. This standard does not purport to address
testing apparatus used to induce electrical potential across the
all of the safety concerns, if any, associated with its use. It is
conductive-backed geomembrane.
the responsibility of the user of this standard to establish
3.2.3 current, n—the flow of electricity or the flow of
appropriate safety, health, and environmental practices and
electric charge.
determine the applicability of regulatory limitations prior to
use. 3.2.4 electrical leak location, n—a method which uses
electrical current or electrical potential to locate leaks in a
geomembrane.
This practice is under the jurisdiction of ASTM Committee D35 on Geosyn-
thetics and is the direct responsibility of Subcommittee D35.10 on Geomembranes. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved Feb. 1, 2018. Published February 2018. Originally contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
published in 2006. Last previous edition approved 2011 as D7240 – 06 (2011). DOI: Standards volume information, refer to the standard’s Document Summary page on
10.1520/D7240-18. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D7240 − 18
3.2.5 electrically isolated conductive-backed geomembrane 4.5 Electrical leak location methods are an effective and
installation, n—an installation of conductive-backed geomem- proven quality assurance measure to detect and locate leaks.
brane that achieves a continuously conductive surface on the
5. Principles and Context of Exposed Geomembrane
bottomlayer,whileelectricallyisolatingthebottomconductive
Electrical Leak Location Methods
layer from the top insulating layer of the entire geomembrane
installation.
5.1 Principles of the Electrical Leak Location Methods for
3.2.6 false positive, n—an alarm or spark, or both, generated Exposed Geomembranes:
by the spark testing equipment on a feature that is not an actual 5.1.1 The principle of the electrical leak location methods is
breach in the geomembrane. to place a voltage across a geomembrane and then locate areas
where electrical current flows through leaks in the geomem-
3.2.7 leak, n—for the purposes of this document, a leak is
brane.
any unintended opening, perforation, breach, slit, tear,
5.1.2 The spark testing method is only applicable to
puncture, crack, or seam breach. Significant amounts of liquids
conductive-backed geomembranes.
or solids may or may not flow through a leak. Scratches,
5.1.3 Typical installations of conductive-backed geomem-
gouges, dents, or other aberrations that do not completely
branes can be spark tested to within about 100 mm of the seam
penetrate the geomembrane are not considered to be leaks.
edge. The seams are then tested with the appropriate seam
Types of leaks detected during surveys include but are not
testing method such as Practice D5641/D5641M or D5820.
limitedto:burns,circularholes,linearcuts,seamdefects,tears,
5.1.4 In electrically isolated conductive-backed geomem-
punctures, and material defects.
brane installations, it may also be possible to spark test the
3.2.8 wand, n—for the purposes of this document, any rod
seams.
that has a conductive element that is attached to a power source
5.1.5 Electrical leak location methods in addition to the
to initiate the spark test.
spark testing method may be used on electrically isolated
conductive-backed geomembrane installations. Available
4. Significance and Use
methods for exposed and covered geomembranes are detailed
4.1 Geomembranes are used as barriers to prevent liquids
in Guide D6747.
fromleakingfromlandfills,ponds,andothercontainments.For
this purpose, it is desirable that the geomembrane have as little
6. Spark Testing Method
leakage as practical.
6.1 A summary of the method is presented in Table 1.
4.2 The liquids may contain contaminants which, if
6.2 Principles of the Spark Testing Method:
released, can cause damage to the environment. Leaking
6.2.1 The principle of this electrical leak location method is
liquids can erode the subgrade, causing further damage.
that the nonconductive (insulating) layer(s) of the geomem-
Leakage can result in product loss or otherwise prevent the
brane acts as a dielectric in a capacitor, which provides a low
installation from performing its intended containment purpose.
impedance through the geomembrane. The capacitor formed
4.3 Geomembranes are often assembled in the field, either
by the conductive pad, the geomembrane, and the conductive
by unrolling and welding panels of the geomembrane material
layer provides capacitive coupling between one output of a
together in the field, unfolding flexible geomembranes in the
high-voltage power supply to the underlying conductive layer.
field, or a combination of both.
The area is then swept with a test wand to locate points where
4.4 Geomembrane leaks can be caused by poor quality of thecapacitordischargesthroughaleak.Oncethesystemsenses
the subgrade, poor quality of the mat
...

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 the previous version. Because
it 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 version
of the standard as published by ASTM is to be considered the official document.
Designation: D7240 − 06 (Reapproved 2011) D7240 − 18
Standard Practice for
Electrical Leak Location usingUsing Geomembranes with an
Insulating Layer in Intimate Contact with a Conductive
Layer via Electrical Capacitance Technique
(Conductive(Conductive-Backed Geomembrane Spark Test)
This standard is issued under the fixed designation D7240; 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 standardpractice is a performance-based practice for using the spark test to electrically locate standard for an electrical
method for locating leaks in exposed geomembranes with an insulating layer that are in intimate contact with a conductive layer.
conductive-backed geomembranes. For clarity, this documentpractice uses the term ‘leak’“leak” to mean holes, punctures, tears,
cuts, cracks knife cuts, seam defects, cracks, and similar breaches over the partial or entire area of in an installed geomembrane
(as defined in 3.2.33.2.7).
1.2 This test method practice can be used on exposedfor conductive-backed geomembranes installed in basins, ponds, tanks, ore
and waste pads, landfill cells, landfill caps, canals, and other containment facilities. This standard It is applicable for geomembranes
in direct and intimate contact with a conductive surface or with a conductive layer integrally included.conductive-backed
geomembranes made of materials such as polyethylene, polypropylene, polyvinyl chloride, chlorosulfonated polyethylene,
bituminous geomembrane, and any other electrically insulating materials. This practice is best applicable for locating
conductive-backed geomembrane leaks where the proper preparations have been made during the construction of the facility.
1.3 SAFETY WARNING:For The electrical methods used for geomembrane leak location use high voltage, low current power
supplies, resulting in the potential for electrical shock. The electrical methods used for geomembrane leak location should be
attempted by only qualified and experienced personnel. Appropriate safety measures must be taken to protect the leakelectrical leak
location of conductive-backed geomembranes using methods in lieu of or in addition to the spark testing method, the installation
must be electrically isolated (as defined in 3.2.5location 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 The spark test may produce an electrical spark and therefore should only be used where an electrical spark would not create
a hazard. This standard does not purport to address all of the safety and liability concerns, if any, associated with its use. It is the
responsibility of the user of this standard to establish appropriate safety safety, health, and healthenvironmental practices and
determine the applicability of regulatory limitations prior to use.
1.6 This international standard was developed in accordance with internationally recognized principles on standardization
established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued
by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
2. Referenced Documents
2.1 ASTM Standards:
D4439 Terminology for Geosynthetics
D5641/D5641M Practice for Geomembrane Seam Evaluation by Vacuum Chamber
D5820 Practice for Pressurized Air Channel Evaluation of Dual Seamed Geomembranes
D6747 Guide for Selection of Techniques for Electrical Leak Location of Leaks in Geomembranes
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 June 1, 2011Feb. 1, 2018. Published July 2011February 2018. Originally published in 2006. Last previous edition approved 20062011 as
D7240D7240 – 06 (2011).–06. DOI: 10.1520/D7240-06R11.10.1520/D7240-18.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. 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
D7240 − 18
3. Terminology
3.1 Definition of terms applying to this test method appear in Terminology D4439.
3.1 Definitions:
3.1.1 For general definitions used in this practice, refer to Terminology D4439.
3.2 Definitions:Definitions of Terms Specific to This Standard:
3.2.1 conductive-backed geomembrane, n—a specialty geomembrane manufactured using coextrusion technology, featuring an
insulating layer in intimate contact with a conductive layer.
3.2.2 coupling pad, n—an electrically conductive pad placed on top of the geomembrane and connected to the spark testing
apparatus used to induce electrical potential across the conductive-backed geomembrane.
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. locate
leaks in a geomembrane.
3.2.5 geomembrane, electrically isolated conductive-backed geomembrane installation, n—an essentially impermeable mem-
brane used with foundation, soil, rock, earth or any other geotechnical engineering related material as an integral part of a man
made project, structure, or system. installation of conductive-backed geomembrane that achieves a continuously conductive surface
on the bottom layer, while electrically isolating the bottom conductive layer from the top insulating layer of the entire
geomembrane installation.
3.2.6 false positive, n—an alarm or spark, or both, generated by the spark testing equipment on a feature that is not an actual
breach in the geomembrane.
3.2.7 leak, n—Forfor the purposes of this document, a leak is any unintended opening, perforation, breach, slit, tear, puncture
or crack. 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. Types of leaks
detected during surveys include but are not limited to: burns, circular holes, linear cuts, seam defects, tears, punctures, and material
defects.
Leaks detected during surveys have been grouped into three categories:
• Holes – round shaped voids with downward or upward protruding rims
• Tears – linear or circular voids with irregular edge borders
• Linear cuts – linear voids with neat close edges
3.2.4 intimate contact, n—for the purposes of this document, intimate contact is when a conductive layer is in direct contact with
the insulating geomembrane, and there are no gaps between the two layers to prohibit the flow of current.
3.2.5 leak detection sensitivity, n—The smallest size 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 be reliably detected.
3.2.8 wand, n—for the purposes of this document, any rod that has a conductive brushelement that is attached to a power source
to initiate the spark test.
4. Summary of Practice
4.1 The principle of this electrical leak location method is to use a high voltage pulsed power supply to charge a capacitor
formed by the underlying conductive layer, the non-conductive layer of the geomembrane and a coupling pad. The area is then
swept with a test wand to locate points where the capacitor discharges through a leak. Once the system senses the discharge current,
it is converted into an audible alarm.
4.2 General Principles
4.2.1 Fig. 1 shows a wiring diagram of the coupling pad, power supply and test wand for the electrical leak location method
of a geomembrane with a lower conductive layer. Once all necessary connections are made, the pad is placed on the upper surface
of the geomembrane. The nonconductive (insulating layer(s)) of the geomembrane act as a dielectric in a capacitor which stores
electrical potential across the geomembrane.
4.2.2 A grid, test lanes or other acceptable system should be used to ensure that the entire area is tested with the test wand.
4.2.3 Either a hand held wand or a larger wand mounted to an all terrain vehicle may be used. Generally a hand held wand is
a more efficient method unless the area is quite large and flat.
4.3 Preparations and Measurement Considerations
4.3.1 Testing must be performed on geomembranes that are clean and dry. For geomembrane covered by water or soils, other
test procedures, such as described in Guide D6747 will have to be used for testing the geomembrane.
4.3.2 Fusion and extrusion welds must be tested using state of the practice nondestructive methods such as air channel test and
vacuum box test, respectively. If the test wand gets too close to the edge of the conductive geomembrane, the electrical charge can
arc to the back side of the conductive geomembrane and may cause a false positive.
D7240 − 18
FIG. 1 Wiring Diagram of the Equipment Required for Spark Testing Geomembrane in Intimate Contact With a Conductive Surfac-
e.Spark Testing Method
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 thatwhich, 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, or unfolding smaller flexible geomembranes in the field. field, or a combination of both.
4.4 In exposed geomembrane applications, geomembrane 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 final and proven quality assurance measure to locate previously
undetecteddetect and locate leaks.
6. Procedure
6.1 Before beginning a leak survey, the equipment must be checked to ensure it is in working order. The power source should
have a range of voltage from 15,000 to 35,000 volts. A wider voltage range is acceptable but the maximum is typically 35,000 volts.
The test wand may be up to 6 feet wide with a brass brush. The coupling pad should be connected as shown in Fig. 1.
6.2 Once the equipment has been checked and wired properly, a trial test must be performed. A puncture (deliberate defect)
should be introduced in a test piece of geomembrane. The deliberate defect should be approximately 1 mm in diameter. The test
piece of geomembrane must be of sufficient size to enable movement of the brush at normal testing speed over the deliberate defect
without touching the edges of the test piece or the coupling pad.
6.3 Place the test piece on a large scrap of geomembrane or on the installed geomembrane with the conductive side down. The
del
...