Graf 320001 Instrucciones Para La Instalacion Y Mantenimiento página 14

6.2.4 Slope, embankment, etc.
On installation of the tank in the immediate vicinity
(< 5 m) of a slope, earthen mound or slope, a
statically calculated supporting wall must be erected
to absorb the soil pressure. The wall must exceed
the dimensions of the tank by at least 500 mm in all
directions, and must be located at least 500 mm
away from the tank.
6.2.5 Installation next to accessible areas
When installing the tanks near accessible areas, it
has to be provided that occurring strains by vehicles
are not transferred to the tanks. The angle of the
fictitious connection line between outer edge of the
thoroughfare area and lower edge of the tank must
be 45° at the most, i.e. the minimum distance to the
accessible area is 2.6 m.
6.2.6 Connection several tanks
Two or more tanks are connected using the mounting areas situated on the bottom of the tanks via GRAF
expansion kit (Order No. 322008) and plastic tubes used for underground installation (to be provided by
the customer). The recesses have to be drilled using the GRAF special bit drill (Order No. 332001) in the
corresponding size. It has to be paid attention to the distance between the tanks not falling below
800 mm. The plastic tubes used for underground installation have to extend into the tanks at least
200 mm. If more than two tanks are connected, a connection on the upper side for ventilation purposes
has to be made along with the connection on the lower side.
6.2.7 Insertion and backfilling
The tanks have to be introduced into the prepared excavation pit without impacts using appropriate
equipment (see also point 4 - Transport and storage)
In order to avoid deformations, the tank is filled with water up to 1/3 of its volume before starting to
backfill the tank coating. Afterwards, the coating (rounded gravel max. granulation 8/16 according to
DIN 4226-1) is backfilled and compressed layer-wise in steps of maximum 30 cm until reaching 1/3 of the
height. Then, the tank is filled with water up to 2/3 of its volume and backfilled and compressed with
layers of 30 cm again until reaching 2/3 of the height, etc. The individual layers have to be compressed
properly (hand rammer). Damaging the tank during compacting is to be avoided. Mechanical compression
machines must not be used in any case. The coating has to have a width of at least 500 mm.
6. Overground and underground installation
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supporting tube
supporting
tube