When an alternating current voltage is applied to a disposal yard with leakage in the geomembrane sheet, the current through the leakage can be extracted from the total current by a phase sensitive detector, compared with the phase of the applied alternating voltage. By placing a set of linear electrodes in parallel and at equal intervals above the geomembran:e and another set below the membrane but orthogonal to the upper set, leakage position can be determined by the electrical current flowing between selected electrodes above and below the sheet. The observed performance of the system in experiments shows that: (1) except in wet condition, 2 cm2 leakage can be pinpointed and existence of 1 cm2 leakage can be determined, (2) smaller interval of electrodes improves the accuracy of the leakage detection and (3) the buried electrical conductors may not hinder detection of the leakage positions.
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