Geosynthetics

Attenuation systems

Off-line tank & On-line tank

The membrane surrounding the FlowBlockTM has to be sufficiently robust to resist damage during construction and over the service life of the tank. The membrane also needs to span across the gaps on the side of the FlowBlockTM requiring sufficient tensile strength. To achieve this a robust membrane with welded joints is required — typically 1mm thick with welded joints and installed by a specialist contractor...

A few pounds saved by installing a poor quality membrane will be minor in comparison to the costs that will occur if the tank leaks. This can result in groundwater pollution, settlement of paved areas and car parks or the undermining of foundations.

In line with industry guidelines, and as advised by Ciria, we recommend that all attenuation systems use a fully welded membrane solution installed by qualified technicians.

On-line tank

Overflow storage tank design off the main drainage network

Off-line tank

Storage tank that is connected to the main drainage network