Geomembrane Leak Detection Surveys

Survey Methodology

All geomembrane leak detection surveys are conducted in accordance with present Environment Agency guidelines.

Portable monitoring electrodes are used to measure the potential difference over the geomembrane cover material on a grid system. The monitoring electrodes usually have a spacing of 1.0 metre.  Data is usually acquired at 1.0 metre intervals along survey lines running at 1.0 metre intervals across the cover material. This equates to the survey being carried out on a 1m grid. Geotect set out the survey grid free of charge.

On site voltages are logged automatically to a digital data logger, enabling immediate download and processing of the data in the field for interpretation and quality control.

In order to ensure the sensitivity of the survey is continuous throughout, simulated trial leaks are performed at the start of the survey and every time the current electrodes are moved.

Data is gathered over an area of approximately 10,000 m² per day (depending on conditions). On completion of each days data gathering, the data is processed. Voltage profiles of each survey line and contour plots are produced to identify anomalous readings. The locations of all anomalous measurements are brought to the attention of the Contractor the following morning, when they can be pinpointed and exposed.

After the repair of any identified defects, a resurvey is carried out to ensure that the defect has been repaired and that it was not masking another anomaly.  The resurvey is carried out over an area of twice the size of the original anomaly and logged as before.

Following completion of the survey a report is issued within five working days of demobilisation. The report includes a general methodology and the survey results.  The main survey, trial leak and resurvey results are presented as colour contour plots.