Geomembranes without installed monitoring system can also be investigated, under certain conditions. In order to perform the survey, the geomembrane should be cleaned at the edge of the pond, the liquid should not be in contact with the geomembrane outside the pond, otherwise it will distort the survey results. With this method our company detected leaks in leaking ponds, at several sites in Hungary.
During the survey, in parallel with the side of the ponds electrical potential is measured on the electrodes placed every meter. The value of the potential decreases in reverse proportion to the location of the current source. Meaning that converging towards the source of the current (i.e. leak), the electrical potential values should increase, and the maximum value will mark the leak. On the below figure the measured electrical potential values are shown.
The defects of the geomembrane act as current source during the analysis. The survey results show the measured electrical potential values, whose maximum value marks the point(s) next to the side where the current flows out of the pond. As the geomembrane is electrically insulative, the location of the current outflow is the same as the leak on the geomembrane.
In the next example the results of the survey and the detected leak can be seen.