Trench - Graf 319039 Instrucciones De Instalación Y Mantenimiento

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6. Installation and assembly
6.2

Trench

To ensure that sufficient working space is available, the base area of the trench must exceed the tank
dimensions by 500 mm on all sides. The distance from fixed structures must be at least 1000 mm.
The embankment should be built in accordance with DIN 4124. The foundation must be horizontal and
even and must offer sufficient load-bearing capacity.
The trench must be deep enough that the maximum earth cover above the tank
(see 2 - Installation Conditions) is not exceeded. For the system to be usable all year round, the tank and
water-carrying parts must be installed in a frost-free zone. The frost-free depth is usually around 800 mm;
for accurate information, please contact the responsible authority.
The substructure is made from a layer of compacted round gravel (grain 8/16 in accordance with
DIN 4226- 1, approx. 100 mm thick). If the ground is non-load-bearing, a reinforced lean concrete slab
approx. 100 mm thick must be made.
6.2.1 Groundwater and cohesive (non-water-permeable) soils
The maximum anticipated groundwater level must
not be higher than the top edge of the cylinder
jacket. The minimum earth covering is 600 mm
(maximum 1000 mm). If the tank is submerged in
groundwater by less than 400 mm, a minimum
covering of over 400 mm is required.
If it is likely that the groundwater level will rise
above the top edge of the cylinder jacket, sufficient
drainage must be installed. The drainage system
must end in a vertical pipe in which a submersible
pressure pump is fitted to pump out the excess
water.
The pump should be checked regularly. The size of the pipe depends on the size of submersible pump
used. The float switch must be able to function fully at all times.
6.2.2 Positioning on a slope, embankment etc.
If the tank is installed in immediate proximity (less
than 5 m) to a slope, mound or embankment, a
statically calculated supporting wall must be
constructed to bear the pressure of the soil. The
wall must exceed the tank dimensions by at least
500 mm in all directions and must be at least
1200 mm away from the tank.
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