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H
>H
>800 <1200
Max.
Max.
>700 <1200
5.
5.1
Construction site
Under all circumstances, the following points must be clarified prior to installation:
The structural suitability of the ground according to DIN 18196
Maximum groundwater levels which occur and drainage capability of the subsoil
Types of load which occur, e.g. traffic loads
An expert ground report should be requested from the local planning authority to determine the physical
characteristics of the subsoil.
5.2
Trench
To ensure that sufficient space is available for working, the base area of the trench must exceed the
dimensions of the tank by > 100 mm on each side; the distance from solid constructions must be at least
1000 mm.
If the depth of the trench is > 1250 mm an embankment must be designed according to DIN 4124. The
construction site must be horizontal and plane and must guarantee sufficient load-bearing capacity.
The depth of the trench must be dimensioned so that the max. earth coverage (see point 2
– installation
conditions) above the tank is not exceeded. To use the system throughout the entire year, it is necessary
to install the tank and those parts of the system which conduct water in the frost-free area. The frost-free
depth is usually approx. 600 mm
– 800 mm; precise information in this regard can be obtained from the
responsible authority.
A layer of compacted, round-grain gravel (grain size 8/16, thickness approx. 100 - 150 mm) is applied as
the foundation.
5.2.1 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 1000 mm
away from the tank.
5.2.2 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
1500 L
3000 L
5000 L
7500 L
max. immersion depth
700 mm
735 mm
950 mm
1250 mm
5.2.3 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.
