Construction & Installation Of Attenuation Tank; Installation Of Attenuation Tank; Laying Geomembrane And Geotextile - Graf ECO BLOC INSPECT FLEX Notice D'installation

8. Construction & installation of attenuation tank
8. Construction & installation of attenuation tank
8.1

Installation of attenuation tank

Chapters 7.1 and 7.2 describe how to prepare the
excavation and lay the first layer of geotextile.
8.2

Laying geomembrane and geotextile

Further steps follow laying the first layer of
geotextile.
The water-impermeable membrane is placed on
the first sheet of geotextile, followed by another
layer of geotextile. This three-layered surround
provides protection and a water-tight shell.
GRAF and your local trading partner remain at
your service for any further information or advice
concerning waterproof film.
8.3 Construction & installation of attenuation tank
For use as a retention tank, a flow controller or a drainage throttle should be installed in a separate shaft.
GRAF and your local trading partner remain at your service for any further information or advice.
Please note:
When setting up a retention tank, it is essential to note the groundwater level. An accumulation of
groundwater may cause uplift, resulting in damage to the system and its surroundings.
If you intend to install in groundwater, please consult with GRAF beforehand. Please provide
GRAF with the necessary information about the construction project (soil cover, groundwater
level, loading etc.) and consult on this.
Depending on the soil type, heavy rainfall may cause local rises in standing groundwater,
particularly in the filling material of the trench. When installing the retention system, check again
that no compression of the subsoil or silting-up has taken place during the construction phase.
It may be necessary to install extra drainage. GRAF will be happy to provide advice on this.
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