Dipole Method

Like the water puddle method, the dipole method (standardized by ASTM standard D7007) is a geoelectrical technique that allows technicians to identify faults in the geomembrane material made during installation

Again, the dipole method uses the electrical insulation properties of the geomembrane material to identify and locate faults (see figure below). However, whilst the water puddle method requires an external water source to humidify the membrane surface, the dipole method passes an electrical charge (around 500V DC) directly into sand or soil material covering the geomembrane.

If any faults are present in the membrane, this charge will pass through the fault to a grounding electrode placed in the earth outside the test site, generating an electrical signature identifiable by a qualified technician. These faults can then be localised, providing a full profile of the membrane’s material integrity. Groupe Alphard applies the method as standardised by ASTM standard D7007.