The geologger® system
This system was first employed in Germany in the 1990s and since then has undergone further developments to make it suitable for a further range of applications. The geologger manufactured by PROGEO Monitoring GmbH in Großbeeren is now is in use in many countries.
The survey method employed facilitates the effective inspection of an entire sealing system. The survey is performed quickly and to a large extent independently of any load or work being undertaken above the sealing system. There is extremely precise localisation of any breaches.
The required cabling is installed when the sealing system is constructed. Inspection can then be undertaken with the help of these cables using either mobile or static measuring equipment.
An electrical technique is employed. An electrical signal is generated on one side of the synthetic membrane and the arrival of this signal is detected simultaneously on the other. As the synthetic liner sheet itself provides electrical insulation , the signal will only be recorded on the measuring side if damage is present.
Simple and durable
The installed cables are particularly durable. During the BAM certification body accreditation procedure, it was confirmed that the geologger® Carbon system has a service life of at least 30 years. Cables and detection contacts are extremely robust and are adapted to the loads and stresses associated with underground constructions. The cables have a ductility of over 10% and are therefore also able to withstand local subsidence without damage.
The fundamental components of the system are the detection cables, which must be installed before the synthetic liner sheet. These cables are unrolled at intervals of several metres in parallel and measured to size.
Thanks to the complete prefabrication of the cables, this work can also be carried out by the synthetic liner installer or by the construction company without hindering the progress of the construction schedule.
OFFLINE/ONLINE measurement technology
All cables are routed through the edge area of the liner into a switch cabinet, where they are connected. There are two possible operating modes:
OFFLINE: A mobile measuring device is connected to the cables in the cabinet to undertake the survey and then removed once the procedure is complete.
ONLINE: All cables are permanently connected to a detection device which is installed in the cabinet. The detection system is operated via a web server.
Analysis and display
The results are clear-cut and can be readily displayed in understandable form. The locations of any leaks are identified conspicuously and precisely.
The entire extent of a membrane can be inspected for the slightest leak with the help of this electrical technique. Thanks to interpolation, accuracy of the detection of leaks is significantly better than the actual interval between electrodes.