We are frequently asked whether leak location can be
performed on geocomposite clay liner (GCL) materials. The
answer is always the same: as long as the liner is not
completely dried out, leak location is possible.
Leak location requires a minimum GCL moisture content of
around 5%. In some cases, this GCL materials can exhibit a
moisture content below 5% immediately following their
installation. But one the GCL has been in place for 2-3
days, the capillary activity of the GCL on moisture in the
ground is enough to make the GCL electrically conductive.
So, it bears repeating: geocomposite clay liners do not
prevent electrical leak location!
The following photographs show two leaks detected with the
dipole method (ASTM D7007) on a geomembrane installed on a
GCL layer. The stakes indicate the location of the leaks.
The first leak passed through both the geomembrane and the
GCL, and in such cases the GCL poses no problem for leak
In the second case the leak was only in the liner and the
GCL was intact, but the leak was nevertheless easy to
locate using standard dipole methods. Groupe Alphard’s
technicians have located a large number of leaks in
geomembranes installed on GCL layers over the years, so it
bears repeating: geocomposite clay liners do not prevent
electrical leak location!