In principle, all PEHD membrane sealing systems can be inspected using this method. Typical applications are listed below. As part of the tendering process, ELD will evaluate the technical background conditions that are relevant to monitoring and ensure the optimal preparation of the system for performing a survey.
Landfill base liners
There are several phases of preparation of landfill base liners, starting with the positioning of the membrane, until these can be covered with several metres of refuse. These membranes may be damaged during preparation, but can also be inspected and repaired. It is advisable to undertake inspections at regular intervals.
Areas which are already covered and are many meters below the surface and which are therefore no longer readily accessible for repair should nevertheless be inspected if there is any concrete reason to suspect that their integrity could have been impaired, for example as a result of fire.
For reasons of environmental protection, basins often need to be leakproof, e.g. seepage basins on landfill sites. However, it can also be important to ensure, for example, that valuable water does not escape into the subsoil undetected.
Due to the diversity of basin types, there are also many different possible technical solutions that can be used for monitoring them. Ideally, a detection cable network should be installed when the basin is built. However, if the conditions are favourable, the leak-proofing characteristics of existing basins can be determined even when these are filled.
Areas used to store substances which could represent a hazard if they escape into groundwater must also be leakproof in case accidents occur.
If these membranes are installed as two synthetic liner sheets, then the detection cables can be positioned between both the sheets together with an electrically conductive fleece. Thus their leak integrity can also be verified when the membrane is no longer directly accessible through the surface, for example, because it is covered with concrete.
Landfill surface liners
Unlike base liners, surface liners are not buried at some point under many metres of waste and instead are usually protected over the course of many years only by a 1-metre thick mineral layer. As a result, there can be uncertainty about the integrity of their leak-proofing characteristics, particularly if the land is subsequently used for other purposes; however, at the same time, repairs are also possible at reasonable cost if the location of any damage can be established.
Retrofitting in existing landfill site surface liner systems
It is also possible to retrofit a monitoring system in existing surface sealing liners without impairing the synthetic liner sheet or the immediately adjacent functional layers. For this purpose, cable trenches must be dug in the recultivation layer above the drainage layer. The detection cables are then laid in these trenches.
In the mining industry, dams are built in order to create large storage basins.
In the event of undetected damage, internal erosion can occur in the dam, and as a result, dam stability can also be affected at certain points. This risk can be minimised significantly by regular monitoring and repair as and when required, especially during and shortly after construction.