4rain FLAT S Notice D'installation Et D'entretien page 42

5.1 Overview
Fig. 21: Recommended installation – example with FLAT
5.2 Foundation
The following criteria must be verified prior to installation:
•
The structural suitability of the soil in accordance with DIN 18196
•
Maximum groundwater levels / drainage of the subsoil
A soil survey should be requested from the local building authority to determine the physical properties of
the soil.
5.3 Pit
To ensure that sufficient working space is available, the base area of the pit must exceed the tank dimen-
sions by > 500 mm on all sides. The distance from fixed structures must be at least 1000 mm.
If the trench depth is greater than 1250 mm, an 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 covering (760 mm above tank shoulder) 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 600 mm; for accurate information, please con-
tact the responsible authority.
5.3.1 Substructure
FLAT and COMPACT tanks
Lay the substructure in the form of a layer of round gravel (max grain size 8/16 mm, depth 100–
150 mm).
MODULARIS tank
Lay the substructure in the form of a layer of chips (max grain size 2/5 mm, depth 100–150 mm).
info@4rain.com
www.4rain.com
5 Installation and assembly
42 / 108

Soil

Cover (shaft ring and shaft
cover)

Tank dome

Covering layer

Surround
(round gravel8/16)

FLAT flat tank

Compacted base layer
β embankment angle (DIN
4124) from pit depth of
1250 mm