Defect in a geomembrane created by sheer tension
Below is a series of pictures of a rare fault in a polyethylene geomembrane (HDPE).
The dipole method was used to locate the fault, an electrical leak location method standardised by the ASTM (D7007) and effective on up to 1m of covering materials, with optimal precision at 30cm and below.
The dipole method locates leaks by measuring voltage loss between two points on the covering material layer. Stakes are placed at the two points with the fault being somewhere between the two stakes, and the process is repeated until there are enough pairs of points (usually 2 or 4) to confirm the location of the leak.
In this case, the geomembrane layer had been put under enormous pressure during the installation of the covering material, ultimately leading to the fault. It should always be remembered that geomembrane materials are not suitable for structural applications and should only be used to ensure a site’s impermeability and environmental integrity.