ASTM D7909-21a

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: D7909 − 21 D7909 − 21a
Standard Guide for
Placement of (Blind) Actual Intentional Leaks During
Electrical Leak Location Surveys of Geomembranes
This standard is issued under the fixed designation D7909; 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 guide is for placing (blind) actual leaks in geomembranes before performing an electrical leak location survey. The
geomembranes can be bare (not covered) or can be covered with water or moist soil.
1.2 This guide is intended to serve as an additional quality control/quality assurance (QC/QA) measure to ensure that leaks through
the geomembrane are detectable, site conditions are proper for leak location surveys, and a valid and complete leak location survey
is performed. Because various leak location practitioners use a wide variety of equipment to perform these surveys and have a wide
range of expertise, placement of actual leaks by the owner or owner’s representative helps ensure that the leak location survey is
being performed correctly and completely.
1.3 Placing actual leaks should be done with the consent and knowledge of all involved parties and specifically the “owner” of
the geomembrane. Geomembranes are typically purchased and installed by dedicated geosynthetic installers who “own” the
geomembrane until the ownership gets transferred to the end user. A project meeting should be set up with the owner, the
consultant, the geosynthetic installers, and the leak location contractor. The intention to use actual create leaks should be clearly
stated by the owner or consultants or both, and the scope and number to be placed should be understood by all parties. The
consultant should broadly identify to the lining contractor a location that can be easily repaired after the test. It is critical that all
actual leaks be included on the liner documentation and repair record drawing.
1.4 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 electrically insulating materials.
(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 shall be taken to
protect the leak location operators as well as other people at the site.)
1.5 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.6 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.
This guide is under the jurisdiction of ASTM Committee D35 on Geosynthetics and is the direct responsibility of Subcommittee D35.10 on Geomembranes.
Current edition approved Feb. 15, 2021May 1, 2021. Published February 2021May 2021. Originally approved in 2014. Last previous edition approved in 20142021 as
D7909 – 14.D7909 – 21. DOI: 10.1520/D7909-21.10.1520/D7909-21A.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D7909 − 21a
1.7 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
D6747 Guide for Selection of Techniques for Electrical Leak Location of Leaks in Geomembranes
D7002 Practice for Electrical Leak Location on Exposed Geomembranes Using the Water Puddle Method
D7007 Practices for Electrical Methods for Locating Leaks in Geomembranes Covered with Water or Earthen Materials
D7240 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)
D7703 Practice for Electrical Leak Location on Exposed Geomembranes Using the Water Lance Method
D7953 Practice for Electrical Leak Location on Exposed Geomembranes Using the Arc Testing Method
D8265 Practices for Electrical Methods for Mapping Leaks in Installed Geomembranes
3. Terminology
3.1 Definitions—For general definitions used in this guide, refer to Terminology D4439.
3.2 Definitions of Terms Specific to This Standard:
3.2.1 actualblind leak, n—for the purposes of this guide, an actuala blind leak is a circular hole in the geomembrane intentionally
placed by the owner or owner’s representative to ensure that the site conditions are suitable for an electrical leak location survey.
A blind actual leak is also referred to as an actual leak in this guide. One actual leak is used for equipment calibration and to gauge
site-specific leak detection sensitivity before beginning in a location unknown to the leak location survey.practitioner.
3.2.2 blind actual leak, n—for the purposes of this guide, a blind actual leak is an actual leak created in a location unknown to
the leak location practitioner.
3.2.2 electrical leak location, n—method that uses electrical current or electrical potential to detect and locate leaks in electrically
isolating geomembranes.
3.2.3 known leak, n—for the purposes of this guide, a known leak is a circular hole in the geomembrane intentionally placed by
the owner or owner’s representative to ensure that the site conditions are suitable for an electrical leak location survey. One known
leak is used for equipment calibration and to gauge site-specific leak detection sensitivity before beginning the leak location survey.
3.2.4 leak, n—for the purposes of this guide, a leak is any unintended opening, perforation, breach, slit, tear, puncture, crack, or
seam breach in electrically isolating geomembranes.
3.2.4.1 Discussion—
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.
4. Significance and Use
4.1 Geomembranes are used as low-permeability barriers to control 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
also erode the subgrade. 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.
4.2 Geomembrane leaks can result even when the quality of the subgrade preparation, the quality of the material placed on the
geomembrane, and the quality of the workmanship are not deficient.
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.
D7909 − 21a
4.3 Electrical leak location methods are an effective final quality assurance (QA) measure to locate previously undetected leaks
in electrically insulating geomembranes. Practices for these implementations are contained in Guide D6747 and Practices D7002,
D7007, D7240, D7703, D7953, and D8265.
4.4 It is important to realize that the detection of leaks depends not only on the capabilities of the leak location equipment,
procedures, and experience of the leak location practitioner, but also on local site conditions that are not under the control of the
leak location practitioner. In particular, to detect a leak, there shall be an electrical conduction path through the leak and through
the materials above and below the leak to allow sufficient electrical current through the leak for detection. Some site conditions,
such as a leak not making contact with the subgrade, dry geotextile, or geocomposite above or below the leak; dry materials above
or below the leak; degree of isolation between the materials above and below the geomembrane; and other factors, may preclude
the detection of leaks. Therefore, the use of a properly placed actual leak is also a test of site preparations and conditions.
4.5 It is not necessarily proper to conclude that, if an actual a leak is not detected, a leak location survey using the proper relevant
ASTM International standard has no validity. Other leaks that have more favorable local conditions and larger leaks may still be
detected.
4.6 The importance of blind actual leaks is to provide an additional measure to assess whether the site conditions throughout the
entire survey area are proper for a leak location survey and that the electric leak location survey is performed correctly and
completely. The use of blind actual leaks provides: (1) a check that the equipment is operating properly, (2) a test for proper survey
coverage, and (3) a check that all survey data (results) have been assessed to confirm a proper survey has been done. These all
result in a high likelihood that significant-sized leaks are detected.
4.7 The placement of blind actual leaks should not replace hiring a reputable and qualified leak location practitioner to perform
the electrical leak location survey. Many site-specific issues and technical limitations can preclude the detection of actual leaks,
but a non-expert will find it difficult to impossible to determine whether the non-detection of actual leaks is due to survey
performance errors or issues with site conditions. It is therefore important to achieve a satisfactory resolution to any issues with
the non-detection of actual leaks but, much more importantly, to check leak location practitioner references and qualifications
before hiring. In addition to checking references from previous clients, qualifications should include reports from at least three
projects completed, similar in cross section to the proposed project, where actual leaks were found. The report output should
provide indisputable evidence that the survey was performed effectively.
4.8 It is important to note that the placement of actual leaks may affect the sensitivity of the electrical leak location survey for
geomembranes covered with soil or water or both. The placement of actual leaks larger than the leaks present in the lining system
may preclude detection of those smaller leaks, especially for highly conductive cover materials.
5. Procedural Guidance for the Placement of (Blind) Actual Leaks
5.1 The fact that actual leak(s) will be installed in the geomembrane, project specification should include: who will install the
leak(s), who will survey the locationslocation(s) of the leak(s), and finally who will repair the leaks leak(s). This should be clearly
described in the project specifications and understood by all affected parties so responsibilities and costs involved are fully
understood by all affected parties. understood. This guide details the placement of one actual leak in a location known to the leak
location practitioner to practitioner, referred to as a “known leak,” to verify site-specific leak location survey functionality and
optionally placing blind actual leak(s). For the geomembrane leak location survey and use of blind actual leaks to be decisive, the
project specifications should also specify the relevant ASTM International standard procedures to be used to perform the
geomembrane leak location survey (see 2.1)
...