Caption title. At head of title: Project summary. Distributed to depository libraries in microfiche. "Sept. 1988." "EPA/600-S2-88-035."

"An electrical method for locating leaks in geomembrane liners was developed and demonstrated for a wide variety of applications. Geomembrane liners are sheets of elastomeric material used to prevent the leakage of waste and to prevent rainwater from infiltrating solid waste landfills and surface impoundments. When no leaks are present, a voltage applied between the material in the liner and the earth under the liner produces a relatively uniform electrical potential distribution in the material in the liner. Leaks are located by mapping the anomaly in the potential distribution caused by current flowing through a leak. A computer simulation model of layered earth sequences above and below an insulating liner with a leak was developed to efficiently predict the effect of a wide range of parameters on the leak signature. Tests on a double-lined physical model demonstrated the applicability of the method for a variety of drainage layers under various test conditions such as leak size, electrode depth, and presence of protective cover soil. Leaks smaller than 0.8 mm in the primary liner can be reliably located to within 10 mm. Leaks in the bottom liner can be detected, but not located. The electrical leak location method was successful in finding a leak in a full-scale impoundment that had been fully tested using the vacuum box method. The method was adapted for locating leaks in the geomembrane liner of landfill cover systems. Scale model tests demonstrated the applicability of the method under a wide range of cover soil thicknesses and leak sizes. Special non-polarizing electrodes were used to locate leaks as small as 3 mm under 600 mm of cover soil."