Retention capacities can be realised with both moulded tanks and storage modules welded in a waterproof plastic liner.
Setup as a Tank
The storage modules have a non-woven 300g sheet of geotextile (or similar) laid over the top of the tanks. They are then wrapped completely in a 1mm LLDPE plastic liner, and then finally in a non-woven 300g geotextile. This setup is referred to as a complete tank.
Setup as a Tray
A simpler example of a tank setup with storage modules is based on the tray principle with an open cover.