The Performance of Electrical Methods for Assessing the Integrity of Geomembrane Liners in Landfill Caps and Waste Storage Ponds

Abstract

Geomembrane leak location methods have been established based on injecting electrical current through the liner into the surrounding soil and then, using pairs of electrodes above the liner, high potential gradients associated with current leakage may be identified. Recently, permanent electrode arrays have been installed at a number of sites as a means of long term monitoring of the integrity of a landfill liner. There has, however, been no scientific study to date which addresses the performance of such systems. Here, we utilise a physical scale model of a landfill liner∕cap and investigate the usefulness of grid based and boundary electrode arrays for detecting multiple leaks in a landfill liner or cap. We compare the two electrode geometries under a series of controlled electrical leak experiments and demonstrate how both these arrangements can detect and locate leaks in a geomembrane. We also demonstrate some of the limitations of the method. For example, present data processing schemes can give misleading results when there are multiple leaks. The influence of variation in resistivity of the soil above or below the liner and also boundary current leakage on the performance of the technique is also studied. The results suggest that these two factors, unless they are accounted for, can have a significant impact on the results and subsequently affect the practical value of electrical leak detection systems.