Analytical study of the performance of a geomembrane leak detection system

摘要

The electrical detection of leaks in geomembranes is a method that allows identifying leakage of contaminants in lined facilities (e.g. sanitary landfills, pollutant ponds, etc.). The procedure in the field involves placing electrodes above and below the geomembrane, to generate an electrical current, which in turn engenders an electric potential distribution in the protective layer (generally a clayey soil). The electric potential will be greater in areas with higher current density, i.e. near leaks. In this study, we combined models from the literature to carry out a parametric analysis to identify the variables that most influence the amplitude of the electrical signals produced by leaks. The basic hypothesis is that the electrical conduction phenomena in a liner system could be depicted by a direct current circuit. After determining the value of the current at the leak, we calculated the electric potential distribution according to the model of Darilek and Laine. This enabled analysing the sensitivity of the parameters, which can be useful in the design of landfills and facilitate the location of leaks. This study showed that geomembranes with low electrical resistance (owing to low thickness, low resistivity, or extensive area) can hinder the leak detection process. In contrast, low thickness and high resistivity of the protection layer magnify the leak signal.