ASTM D7007-03

Standard Practices for Electrical Methods for Locating Leaks in Geomembranes Covered with Water or Earth Materials

SIGNIFICANCE AND USE
Geomembranes are used as impermeable barriers to prevent liquids from leaking from landfills, ponds, and other containments. 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. For these reasons, it is desirable that the geomembrane have as little leakage as practical.  
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.
The most significant causes of leaks in geomembranes that are covered with only water are related to construction activities including pumps and equipment placed on the geomembrane, accidental punctures, and punctures caused by traffic over rocks or debris on the geomembrane or in the subgrade.
The most significant cause of leaks in geomembranes covered with earth materials is construction damage caused by machinery that occurs while placing the earth material on the geomembrane. Such damage also can breach additional layers of the lining system such as geosynthetic clay liners.
Electrical leak location methods are an effective final quality assurance measure to locate previously undetected or missed leaks.
SCOPE
1.1 This standard practice describes standard procedures for using electrical methods to locate leaks in geomembranes covered with water or earth materials containing moisture.
1.2 This standard practice is intended to ensure that leak location 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 to perform these surveys, performance-based operations are used that specify the minimum leak detection performance for the equipment and procedures.
1.3 This standard practice requires that the leak location equipment, procedures, and survey parameters used are demonstrated to result in an established minimum leak detection sensitivity. The survey shall then be conducted using the demonstrated equipment, procedures, and survey parameters.
1.4 Separate procedures are given for leak location surveys for geomembranes covered with water and for geomembranes covered with earth materials. Separate procedures are given for leak detection sensitivity tests using actual and artificial leaks.
1.5 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 of materials such as polyethylene, polypropylene, polyvinyl chloride, chlorosulfonated polyethylene, bituminous material, and other electrically-insulating materials.
1.6 Warning-The 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.
1.7 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.

General Information

• Status: Historical
• Publication Date: 30-Nov-2003
• ICS: 59.080.70 - Geotextiles
• Technical Committee: D35 - Geosynthetics
• Drafting Committee: D35.10 - Geomembranes

Relations

• Replaced By: ASTM D7007-09 - Standard Practices for Electrical Methods for Locating Leaks in Geomembranes Covered with Water or Earth Materials
• Effective Date: 01-Jun-2009
• Referred By: ASTM D6747-21 - Standard Guide for Selection of Techniques for Electrical Leak Location of Leaks in Geomembranes
• Effective Date: 01-Dec-2003
• Referred By: ASTM D7700-22 - Standard Guide for Selecting Test Methods for Geomembrane Seams
• Effective Date: 01-Dec-2003
• Referred By: ASTM D7909-21a - Standard Guide for Placement of Intentional Leaks During Electrical Leak Location Surveys of Geomembranes
• Effective Date: 01-Dec-2003

Standards Content (Sample)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation: D 7007 – 03
Standard Practices for
Electrical Methods for Locating Leaks in Geomembranes
Covered with Water or Earth Materials
This standard is issued under the fixed designation D 7007; 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 (e) indicates an editorial change since the last revision or reapproval.
1. Scope attempted only by qualified and experienced personnel.Appro-
priate safety measures must be taken to protect the leak
1.1 This standard practice describes standard procedures for
location operators as well as other people at the site.
using electrical methods to locate leaks in geomembranes
1.7 This standard does not purport to address all of the
covered with water or earth materials containing moisture.
safety concerns, if any, associated with its use. It is the
1.2 This standard practice is intended to ensure that leak
responsibility of the user of this standard to establish appro-
location surveys are performed with demonstrated leak detec-
priate safety and health practices and determine the applica-
tion capability. To allow further innovations, and because
bility of regulatory limitations prior to use.
various leak location practitioners use a wide variety of
procedures and equipment to perform these surveys,
2. Referenced Documents
performance-based operations are used that specify the mini-
2.1 ASTM Standards:
mum leak detection performance for the equipment and pro-
D 4439 Terminology for Geosynthetics
cedures.
D 6747 Guide for Selection of Techniques for Electrical
1.3 This standard practice requires that the leak location
Detection of Potential Leak Paths in Geomembranes
equipment, procedures, and survey parameters used are dem-
onstrated to result in an established minimum leak detection
3. Terminology
sensitivity. The survey shall then be conducted using the
3.1 Definitions of Terms Specific to This Standard:
demonstrated equipment, procedures, and survey parameters.
3.1.1 artificial leak, n—an electrical simulation of a leak in
1.4 Separate procedures are given for leak location surveys
a geomembrane.
for geomembranes covered with water and for geomembranes
3.1.2 current source electrode, n—the electrode that is
covered with earth materials. Separate procedures are given for
placed in the water or earth material above the geomembrane.
leak detection sensitivity tests using actual and artificial leaks.
3.1.3 dipole measurement, n—an electrical measurement
1.5 Leak location surveys can be used on geomembranes
made on or in a partially conductive material using two
installed in basins, ponds, tanks, ore and waste pads, landfill
closely-spaced electrodes.
cells, landfill caps, and other containment facilities. The
3.1.4 earth material, n—sand, gravel, clay, silt, combina-
proceduresareapplicableforgeomembranesmadeofmaterials
tions of these materials, and similar materials with at least
such as polyethylene, polypropylene, polyvinyl chloride, chlo-
minimal moisture for electrical current conduction.
rosulfonated polyethylene, bituminous material, and other
3.1.5 leak, n—any unintended opening, perforation, slit,
electrically-insulating materials.
tear, puncture, crack, hole, cut, or similar breaches through an
1.6 Warning—The electrical methods used for geomem-
installed geomembrane. Significant amounts of liquids or
brane leak location could use high voltages, resulting in the
solids might or might not flow through a leak. Scratches,
potential for electrical shock or electrocution. This hazard
gouges, dents, or other aberrations that do not completely
might be increased because operations might be conducted in
penetrate the geomembrane are not considered to be leaks.
or near water. In particular, a high voltage could exist between
3.1.6 leak detection sensitivity, n—the smallest size leak
the water or earth material and earth ground, or any grounded
that the leak location equipment and survey methodology are
conductor. These procedures are potentially VERYDANGER-
capable of detecting under a given set of conditions. The leak
OUS, and can result in personal injury or death. The electrical
detection sensitivity specification is usually stated as a diam-
methods used for geomembrane leak location should be
eter of the smallest leak that can be reliably detected.
1 2
These practices are under the jurisdiction of ASTM Committee D35 on For referenced ASTM standards, visit the ASTM website, www.astm.org, or
GeosyntheticsandisthedirectresponsibilityofSubcommitteeD35.10onGeomem- contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
branes. Standards volume information, refer to the standard’s Document Summary page on
Current edition approved Dec. 1, 2003. Published January 2004. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D7007–03
3.1.7 pole measurement, n—an electrical measurement 4.3.1 Leak location surveys for geomembranes covered
made on or in a partially conductive material using one with water can be conducted with water on the geomembrane
measurement electrode and a remote reference electrode. or with water covering a layer of earth materials on the
3.2 Definitions: geomembrane.
3.2.1 noise, n—the unwanted part of a measured signal 4.3.2 For leak location surveys with water on the geomem-
contributed by phenomena other than the desired signal. brane,usuallyadipoleprobeissystematicallyscannedthrough
3.2.2 potential, n—electrical voltage measured relative to a the water over the geomembrane to locate the points of
reference point. abnormal potential distribution. The dipole spacing is typically
0.2 to 1 metre.
4. Summary of the Leak Location Methods
4.3.3 Various types of probes can be used to perform the
surveys. Some are for when the operator wades in the water;
4.1 The principle of the electrical leak location method is to
some are for towing the probe back and forth across the
place a voltage across a geomembrane and then locate the
geomembrane; and some are for raising and lowering along
points were electrical current flows through discontinuities in
vertical or sloping walls.
the geomembrane.
4.3.4 The probe is typically connected to an electronic
4.2 General Principles:
detector assembly that converts the electrical signal from the
4.2.1 Figs. 1 and 2 show diagrams of the electrical leak
probe to an audible signal that increases in pitch and amplitude
location method for a geomembrane covered with water and
for a geomembrane covered with earth materials respectively. as the leak signal increases.
4.3.5 When a leak signal is detected, the point with the
One output of an electrical excitation power supply is con-
nected to a current source electrode placed in the material maximum signal is then determined. This point of maximum
signal corresponds to the location of the leak. The location of
covering the geomembrane. The other output of the power
supply is connected to an electrode in contact with electrically the leak is then marked or measured relative to fixed points.
4.3.6 The leak detection sensitivity depends on the conduc-
conductive material under the geomembrane.
4.2.2 When there are leaks, electrical current flows through tivity of the materials within, above, and below the leak, the
electrical homogeneity of the material above the leak, the
the leaks, which produces high current density and a localized
abnormality in the potential distribution in the material above output level of the excitation power supply, the design of the
measurement probe, the sensitivity of the detector electronics,
the geomembrane. Electrical measurements are made to locate
those areas of abnormal signal at the leaks. and the survey procedures. Leaks as small as 1 mm in diameter
have been routinely found, including tortuous leaks through
4.2.3 Measurements are made using a dipole or pole mea-
surement configuration. Various types of data acquisition are welds in the geomembrane. Leaks larger than 25 mm in
diameter can usually be detected from several metres away.
used, including audio indications of the signal level, manual
measurements with manual recording of data, and automated 4.3.7 The survey rate depends primarily on the spacing
between scans and the depth of the water. A close spacing
digital data acquisition.
4.2.4 Directcurrent and alternating current excitationpower between scans is needed to detect the smallest leaks.
4.4 Leak Location Surveys of Geomembranes Covered with
supplies and potential measurement systems have been used
for leak location surveys. Earth Materials:
4.3 Leak Location Surveys of Geomembranes Covered with 4.4.1 For leak location surveys with earth materials cover-
Water: ing the geomembrane, point-by-point measurements are made
FIG. 1 Diagram of the Electrical Leak Location Method for Surveys with Water Covering the Geomembrane
D7007–03
FIG. 2 Diagram of the Electrical Leak Location Method for Surveys with Earth Material Covering the Geomembrane
on the earth material using either dipole measurements or pole containments. The liquids may contain contaminants that if
measurements. Dipole measurements are typically made with a released can cause damage to the environment. Leaking liquids
spacing of 0.5 to 5 metres. Measurements are typically made can erode the subgrade, causing further damage. Leakage can
along parallel survey lines or on a grid pattern. result in product loss or otherwise prevent the installation from
4.4.2 The survey procedures are conducted in a systematic performing its intended containment purpose. For these rea-
data collection mode. The measurements and positions are sons,itisdesirablethatthegeomembranehaveaslittleleakage
recorded manually or using a digital data acquisition system. as practical.
4.4.3 The data is typically downloaded or manually entered 5.2 Geomembrane leaks can be caused by poor quality of
into a computer and plotted. Sometimes data is taken along the subgrade, poor quality of the material placed on the
survey lines and plotted in raster. Sometimes data is taken in a geomembrane, accidents, poor workmanship, and carelessness.
grid pattern and plotted in two-dimensional contour, shade of 5.3 The most significant causes of leaks in geomembranes
gray, or color contour plots, or in three-dimensional represen- that are covered with only water are related to construction
tations of the contours. The data plots are examined for activities including pumps and equipment placed on the
characteristic leak signals. geomembrane, accidental punctures, and punctures caused by
4.4.4 The approximate location of the leak signal is deter- traffic over rocks or debris on the geomembrane or in the
minedfromtheplotsandadditionalmeasurementsaremadeon subgrade.
the earth material in the vicinity of the detected leak signal to 5.4 The most significant cause of leaks in geomembranes
accurately determine the position of the leak. covered with earth materials is construction damage caused by
4.4.5 The leak detection sensitivity depends on the conduc- machinery that occurs while placing the earth material on the
tivity of the materials within, above, and below the leak, the geomembrane. Such damage also can breach additional layers
electrical homogeneity of the material above the leak, the of the lining system such as geosynthetic clay liners.
design of the measurement electrodes, the output level of the 5.5 Electrical leak location methods are an effective final
excitation power supply, the sensitivity of the detector elec- quality assurance measure to locate previously undetected or
tronics, the survey procedures, and data interpretation methods missed leaks.
and skill. Leaks as small as 5 mm in diameter can be located
6. General Leak Location Survey Procedures
under 600 mm of earth material. Leaks larger than 25 mm in
diameter can usually be detected from several metres away.
6.1 The following measures shall be taken to optimize the
4.4.6 The survey rate depends primarily on the spacing leak location survey:
between the measurement points, the type of data acquisition,
6.1.1 Conductive paths such as metal pipe penetrations,
and whether data interpretation is accomplished in the field.A pump grounds, and batten strips on concrete should be isolated
close spacing between measurement points is needed to ad-
or insulated from the water or earth material on the geomem-
equately replicate the leak signals and to detect smaller leaks. brane whenever practical. These conductive paths conduct
electricity and mask nearby leaks from detection.
5. Significance and Use
6.1.2 In applications where a single geomembrane is cov-
5.1 Geomembranes are used as impermeable barriers to ered with earth materials that overlap the edges of the
prevent liquids from leaking from landfills, ponds, and other geomembrane, if practical, measures should be taken to isolate
D7007–03
the edges. If earth materials overlap the edges of the survey brane.Additional area can be surveyed by placing water on the
area to earth ground, electrical current will flow from the earth earth material on the primary geomembrane.
material to earth ground, causing a large signal that will mask 6.1.5 For surveys with earth materials on the geomembrane,
small leak signals near the edges of the survey area. Isolation the earth materials shall have adequate moisture to provide a
can be accomplished by either: performing the leak location continuous path for electrical current to flow through the leak.
survey before the edges of the geomembrane are covered; Earth materials usually have sufficient moisture at depth, but
removing the earth materials from a narrow path around the sometimes the surface of the earth materials becomes too dry.
perimeter of the geomembrane; or allowing the edge of the This dry material shall be scraped away at the measurement
geomembrane to protrude above the earth materials. points, or the surface shall be wet with water. The earth
6.1.3 There shall be a conductive material below the materials do not have to be saturated with water. The amount
geomembrane being tested to conduct electrical current of moisture required depends on the earth material, the
through the leaks. The detection of a leak depends on the equipment and procedures. Successful leak location surveys
amount of electrical current flowing through it. The current have been conducted on earth materials containing as little as
must flow through the subgrade to complete an electrical 0.5 percent moisture by weigh
...