Envitech offers independent third-party CQA services and Electronic Leak Location (ELL) testing services, which may be required in terms of project specifications or prevailing legislation and regulations. The ELL testing is carried out by qualified and experienced ELL Engineers, and provides the facility owner with increased confidence that damage caused to the geomembrane liner during installation and subsequent backfilling has been located and repaired. ASTM D6747 is normally used as an initial guide to determine the type of ELL test suitable for the application.

ELL testing is carried out using state of the art calibrated equipment and technology, providing engineers, installers, contractors, and facility owners with invaluable information with regards to the integrity of the geosynthetic lining installation.

• Arc test method for exposed geomembranes (ASTM D7953)
  The arc testing method is generally preferred for exposed geomembranes, since no water is required to perform the test and it can be more sensitive than water-based methods because the leak detection does not depend on water getting through the leak. The minimum sensitivity is a 1 mm diameter leak per ASTM D7953, but leaks smaller than that are regularly located.

  A high voltage power supply is applied to a test wand above the geomembrane and is grounded to the underlying conductive layer. The area is swept with the test wand and an electrical arc is formed in the presence of a leak. When the system senses the discharge current arc, it is converted into visual and audio alarms. The test wand can be supplied in custom sizes and shapes for specific applications.

• Dipole test method for earthen or water covered geomembranes (ASTM D7007 or ASTM D8265)

  The Dipole Test Method is used with earthen or water covered geomembranes, typically to verify that an installation has not been damaged during the installation and backfilling process. This type of test requires that the geomembrane is in intimate contact with the subgrade, that the covering material is completely electrically isolated from the surrounds and earth soil, and there is sufficient conductivity in the materials above and below the geomembrane. A high voltage power supply is used to inject a current through the covering material, and a dipole unit is used to take and record voltage readings over a predetermined grid, precisely locating potential damages.

For further information on our range of technical services, please contact us directly at info@envitech.co.za

10mm hole found using dipole

2mm pinhole hole found using dipole method