Graf EcoBloc Inspect smart Notice Pour L'installation, L'utilisation Et L'entretien page 32

8. Structure as retention volume/retention tank
8.1 Structure of retention volume
The preparation of the trench and the laying of the
first geotextile layer is described in sections 7.1
and 7.2.
8.2 Laying geotextile, film and geotextile
Subsequent to laying the initial layer of geotextile,
the next steps involve the placement of a water-
impermeable film atop the first geotextile layer,
succeeded by the addition of another layer of ge-
otextile. This three-layered configuration serves
to provide comprehensive protection and estab-
lish a water-tight shell for the infiltration system.
Should you require any further information or guid-
ance regarding the waterproof film or any related
matters, GRAF and your local trading partner are
available to assist you.
8.3 Structure as retention volume / retention 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 consider the groundwater level. An accumulation
of groundwater may cause uplift, resulting in damage to the system and its surroundings.
If you intend to install the system in groundwater, please consult with GRAF beforehand. Please
provide GRAF with the necessary information about the construction project (soil cover, ground-
water level, loading etc.) and consult on this.
Depending on the soil type, heavy rainfall may cause local rises in stratum water, particularly in the
material used to backfill the trench. When installing the retention system, check again that no com-
paction 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.
8. Structure as retention volume/retention tank
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