ASTM D7703-11
(Practice)Standard Practice for Electrical Leak Location on Exposed Geomembranes Using the Water Lance System
Standard Practice for Electrical Leak Location on Exposed Geomembranes Using the Water Lance System
SIGNIFICANCE AND USE
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.
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.
Geomembranes are often assembled in the field, either by unrolling and welding panels of the geomembrane material together in the field, or unfolding flexible geomembranes in the field.
Geomembrane leaks can be caused by poor quality of the subgrade, poor quality of the material placed on the geomembrane, accidents, poor workmanship, and carelessness. describes the electrical methods for locating leaks in Geomembranes Covered with Water or Earth Materials.
Electrical leak location methods are an effective and proven quality assurance measure to locate previously undetected leaks and check the integrity of a liner.
SCOPE
1.1 This standard is a performance-based practice using the water lance system, a electrical method for detecting leaks in exposed geomembranes. For clarity, this document uses the term “leak” to mean holes, punctures, tears, knife cuts, seam defects, cracks and similar breaches in an installed geomembrane.
1.2 This standard 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 electricallyinsulating materials. This standard may not be applicable for locating geomembrane leaks where the proper preparations have not been made during the construction of the facility.
1.3 WarningThe electrical methods used for geomembrane leak location could use high voltages, resulting in the potential for electrical shock or electrocution. This hazard might be increased because operations might be conducted in or near water. In particular, a high voltage could exist between the water or earth material and earth ground, or any grounded conductor. These procedures are potentially VERY DANGEROUS, and can result in personal injury or death. The electrical methods used for geomembrane leak location should be attempted only by qualified and experienced personnel. Appropriate safety measures must be taken to protect the leak location operators as well as other people at the site.
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.
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Designation: D7703 − 11
StandardPractice for
Electrical Leak Location on Exposed Geomembranes Using
the Water Lance System
This standard is issued under the fixed designation D7703; 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 2. Referenced Documents
2.1 ASTM Standards:
1.1 This standard is a performance-based practice using the
D4439 Terminology for Geosynthetics
water lance system, a electrical method for detecting leaks in
D6747 Guide for Selection of Techniques for Electrical
exposed geomembranes. For clarity, this document uses the
Detection of Leaks in Geomembranes
term “leak” to mean holes, punctures, tears, knife cuts, seam
D7007 Practices for Electrical Methods for Locating Leaks
defects, cracks and similar breaches in an installed geomem-
in Geomembranes Covered with Water or Earth Materials
brane.
1.2 Thisstandardcanbeusedforgeomembranesinstalledin 3. Terminology
basins, ponds, tanks, ore and waste pads, landfill cells, landfill
3.1 For general definitions used in this document, refer to
caps, canals, and other containment facilities. It is applicable
D4439.
for geomembranes made of materials such as polyethylene,
3.2 Definitions of Terms Specific to This Standard:
polypropylene, polyvinyl chloride, chlorosulfonated
3.2.1 artificial leak, n—an electrical simulation of a leak in
polyethylene, bituminous geomembrane, and any other electri-
a geomembrane.
callyinsulating materials. This standard may not be applicable
3.2.2 current, n—the flow of electricity or the flow of
for locating geomembrane leaks where the proper preparations
electric charge.
have not been made during the construction of the facility.
3.2.3 electrode, n—the conductive plate that is placed in
1.3 Warning—The electrical methods used for geomem-
earthorinthematerialunderthegeomembraneoraconductive
brane leak location could use high voltages, resulting in the
element typically placed inside the water reservoir.
potential for electrical shock or electrocution. This hazard
3.2.4 electrical leak location, n—a method which uses
might be increased because operations might be conducted
electrical current or electrical potential to detect and locate
in or near water. In particular, a high voltage could exist
leaks.
between the water or earth material and earth ground, or
3.2.5 leak, n—for the purposes of this document, a leak is
any grounded conductor. These procedures are potentially
any unintended opening, perforation, breach, slit, tear,
VERY DANGEROUS, and can result in personal injury or
puncture, crack, or seam breach. Significant amounts of liquids
death. The electrical methods used for geomembrane leak
or solids may or may not flow through a leak. Scratches,
location should be attempted only by qualified and experi-
gouges, dents, or other aberrations that do not completely
enced personnel. Appropriate safety measures must be
penetrate the geomembrane are not considered to be leaks.
taken to protect the leak location operators as well as other
Leaks detected during surveys have been grouped into five
people at the site.
categories:
1.4 This standard does not purport to address all of the
holes— round shaped voids with downward or upward
safety concerns, if any, associated with its use. It is the
protruding rims.
responsibility of the user of this standard to establish appro- tears—linear or areal voids with irregular edge borders.
priate safety and health practices and determine the applica- linear cuts—linear voids with neat close edges.
bility of regulatory limitations prior to use. seam defects— area of partial or total separation between
1 2
This practice is under the jurisdiction of ASTM Committee D35 on Geosyn- For referenced ASTM standards, visit the ASTM website, www.astm.org, or
thetics and is the direct responsibility of Subcommittee D35.10 on Geomembranes. contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Current edition approved June 1, 2011. Published July 2011. DOI: 10.1520/ Standards volume information, refer to the standard’s Document Summary page on
D7703–11. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D7703 − 11
sheets. water source, usually from a small reservoir on top of the liner,
burned through zones—voids created by melting polymer or from a tank truck isolated from ground parked at higher
during welding. elevation, is connected to the water lance using a plastic or
rubber hose.
3.2.6 leak detection sensitivity, n—the smallest leak that the
4.2.2 Direct current power supplies (often a 12 or 24 volt
leak location equipment and survey methodology are capable
battery) have been used for leak location surveys.
of detecting under a given set of conditions. The leak detection
4.2.3 For leak location surveys of exposed geomembrane,
sensitivity specification is usually stated as a diameter of the
the solid water stream (not a spray) is moved systematically
smallest leak that can be reliably detected.
over the geomembrane area to locate the points where the
3.2.7 water stream, n—for the purposes of this document, a
electrical current flow increases as the charged water from the
continuous stream of water between the water lance and the
water lance contacts the oppositely charged conductive media
geomembrane that creates a conduit for current to flow through
under the geomembrane through a hole.
any leaks.
4.2.4 The voltage drop signal between the two electrodes in
3.2.8 water lance, n—for the purposes of this document, a
thewatercolumninthewaterlanceistypicallyconnectedtoan
probe (lance) incorporating two electrodes that directs a solid
electronic detector assembly that converts the electrical signal
stream of water through a single nozzle mounted at the end.
to an audible signal that increases in pitch and amplitude as the
leak signal increases (Fig. 3).
4. Summary of Practice
4.2.5 When a leak signal is detected, the location of the leak
4.1 The Principle of the Electrical Leak Location Method
is then marked or located relative to fixed points.
Using the Water Lance System:
4.2.6 Theleakdetectionsensitivitycanbeverygoodforthis
4.1.1 The principle of the electrical leak location method is
technique. Leaks smaller than 1 mm in diameter are routinely
to place a voltage across a geomembrane and then locate areas
found, including leaks through seams in the geomembrane.
where electrical current flows through leaks. ASTM Standard
4.3 Preparations and Measurement Considerations:
D6747 is a guide for the selection of the various implementa-
4.3.1 Proper field preparations and other measures must be
tions of the method.
implemented to assure an electrical connection to the conduc-
4.1.2 Fig. 1 shows a diagram of the electrical leak location
tive material directly below the geomembrane is in place.
method of the water lance system for exposed geomembranes.
4.3.2 There must be a conductive material directly below
One output of an electrical excitation power supply is con-
the geomembrane being tested. Typically a properly-prepared
nected to an electrode placed in the water reservoir; a pump
subgrade will have sufficient conductivity. Under proper con-
sends this charged water to the water lance (Fig. 2) that jets the
ditions and preparations, geosynthetic clay liners (GCLs) can
water in a solid stream on top of the geomembrane. The other
be adequate as conductive material.There are some conductive
output of the power supply is connected to an electrode placed
geotextiles with successful field experience which can be
in electrically conductive material under the geomembrane.
installed beneath the geomembrane to facilitate electrical leak
4.2 Leak Location Surveys of Exposed Geomembrane Using
survey(thatis,ondrysubgrades,oraspartofaplanardrainage
the Water Lance System:
geocomposite).
4.2.1 The water lance detection system usually consists of a
4.3.3 Measures should be taken to perform the leak location
singlenozzlemountedattheendofaprobe(lance)(Fig.2)that
survey when geomembrane wrinkles are minimized.
directs a solid stream of water onto a geomembrane, and an
electronic detector assembly as shown in Fig. 3. A pressurized NOTE 1—The leak location survey could be conducted at night or early
FIG. 1 Diagram of the Electrical Leak Location Method for Surveys with Water Lance on Exposed Geomembrane
D7703 − 11
FIG. 2 Typical water lance
FIG. 3 Photographs of Water Lance Electronic Detector Assembly
morning when wrinkles are minimized. Sometim
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