5.4.2 Groundwater and cohesive (water-
impermeable) soils (e.g. clay soil)
If it is anticipated that the tanks will be immersed
deeper into the groundwater than is shown in the
adjacent figure, sufficient dissipation must be
ensured. (See table for max. immersion depth).
Dissipation of the drainage water (e.g. via an
annular drainage system) is recommended in the
case of cohesive, water-impermeable soils.
Tank
max. immersion depth
5.4.3 Installation below HGV-bearing surfaces
The shaft can only be driven over with HGV in
conjunction with a self-supporting, iron-reinforced
concrete plate. To ensure that no additional forces
or effects of HGV-bearing are transferred to the
tanks, the dimensions and strength of the concrete
plate must be statically calculated.
If you have any questions in this regard, please
contact your GRAF-Team.
5.4.4 Installation adjacent to surfaces used by
vehicles
If the underground tanks are installed adjacent to
surfaces which are used by heavy vehicles
weighing over 3,5 t, the minimum distance away
from these surfaces is at least the depth of the
trench.
5.4.5 Connection of several tanks
Two or more tanks are connected via the assembly
surfaces by means of GRAF special seals and
basic pipes (to be provided at construction site).
The apertures must be drilled to the corresponding
size using only the GRAF special crown bit. It must
be ensured that the distance between the tanks is
at least 600 mm. The pipes must project at least
200 mm into the tanks.
www.graf.info
5.
Installation and assembly
20.000 l - 65.000 l
1250 mm
>750 <1500 mm
Max.
Max.
> H
/
Max.
> 700 < 1500
Max.
H
min.
600 mm