Trench - Graf CARAT-S Série Notice D'installation

5.3

Trench

To ensure that sufficient space is available for working, the base area of the trench must exceed the
dimensions of the tank by 500 mm on each side; the distance from solid constructions must be at least 1000
mm.
The trench embankment must be designed so that slippage or collapse of the embankment wall is not to be
anticipated. 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. 150 - 200 mm) is applied as the
foundation.
5.3.1 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.
5.3.2 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 size
Immersion depth
5.3.3 Installation adjacent to surfaces used by vehicles
If the underground tanks are installed adjacent to surfaces
which are used by vehicles heavier than passenger cars,
the minimum distance away from these surfaces is at least
the depth of the trench.
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5. Installation and assembly
2700 L
700 US-gallons 1000 US-gallons
700 mm
>800 <1800
3750 L 4800 L
1250 US-gallons
795 mm 910 mm
7 /
6500 L
1700 US-gallons
1050 mm