Geomembrane Leak Detection Surveys

How the Survey Works 

Conducting a leak detection survey over a newly constructed landfill cell is a very cost effective method for finding defects in the geomembrane liner that occur before and during placement of the overlying drainage blanket.

Even with a comprehensive CQA regime small defects, such as knife cuts can be very difficult to identify visually. Damage caused by heavy machinery while installing the drainage blanket is the most significant cause of damage to geomembranes.

The basic principle of a leak detection survey is simple. An electric potential is applied, via two electrodes, between the medium directly above the geomembrane liner and the medium directly beneath the geomembrane liner. In the case of a newly constructed landfill cell electrodes are placed in the engineered clay or substrate and the overlying leachate drainage gravel, as shown in the figure below.

An intact geomembrane liner will act as an insulator and not allow any current to flow between the two mediums. Current will only flow through holes in the geomembrane.

The potential gradients in the overlying medium are then measured by using two mobile monitoring electrodes to locate the high gradient, associated with a hole. The electrical arrangement of the survey is closely related to the direct-current electrical resistivity method.

NOTE - In the above figure the anchor trenches are left open to increase survey sensitivity, for more information see Requirements.