Electrical response of a leak in a geomembrane liner

Abstract

A leak in a geomembrane lined impoundment or landfill has a characteristic electrical response. I simulate the waste material, the liner, and the soil under the liner by infinite horizontal layers and express the secondary potential for a leak in the geomembrane liner in terms of a three‐layer medium Green’s function and the unknown current density distribution at the leak. The area of the leak is sufficiently small for the leak current density to be essentially uniform. I add the primary potential associated with a leak‐free liner to the secondary potential to form an integral equation and derive a general expression for the current density at the boundary between the waste material and the liner. From the expression for the current density, I determine the current flow through the leak by assuming that the total current distribution flows vertically across a finite region of the infinite, thin liner layer. This finite region has the same surface area as does the waste disposal site or landfill. My analysis implies that the current density is the most sensitive variable affecting the magnitude of current flow through the leak and the amplitude of the leak anomaly response. Multiple circular leaks in the thin resistive liner are included in the analysis. The potential anomaly of a leak is a localized response which is capable of providing a useful means for detecting and locating such leaks accurately in large waste disposal sites or landfills. Excellent agreement between experimental and model data shows my general solution is accurate in predicting leak signatures and suggests the solution may be useful to model field data acquired in geomembrane lined impoundments or landfills.