5.2. Excavations
Load-bearing soil is required as subsoil!
The following EV2 value is required for
the soil compaction: 45 MN/sqm.
To provide sufficient working space,
which can also be compacted, the
footprint of the excavations must exceed
the tank size by
≥
400 mm (for a
trafficable variant) and by
≥
200 mm (for
a walkonable variant) on each side.
For a walkonable variant, the tanks can
be placed directly next to each other, for
a trafficable variant the tanks required
≥
400 mm distance between each other.
The distance of the excavations from
fixed structures must be at least 1.00 m.
From excavation depth > 1250 mm, the
excavations must be battered with a
slope to DIN 4124 (with or without
excavation supports – depending on the
requirements and situation)
The depth of the pit must be dimensioned
so that the maximum soil cover (see
section 4 – installation conditions) above
the tank is not exceeded.
For all-year round use of the system, the
tank and the water-carrying parts of the
system must be installed at a frost-free
depth. In general the frost-free depth is
approx. 600 mm (Northern Germany) to
approx. 1200 mm (Austria); contact the
competent authority for the place of
installation for more precise information.
A layer of gravel (max. grading range
0-5 mm stone free, approx. 100-150 mm
thick) is laid and compacted as the
subbase/blinding layer.
5.2.1 Hillside location, slope, etc.
If the tank is installed in the immediate
vicinity (< 5.00 m) of a hill, hillside or
slope, a structurally designed retaining
wall must be built to absorb the soil
pressure; the wall must protrude above
the tank dimensions by at least 500 mm
and be a minimum distance of 1000 mm
from the tank.
If the underground tanks are installed
next to traffic areas, which is used by
heavy vehicles (over 3.5 t) (e.g. adjacent
road), the minimum distance of the tank
from these areas should be at least equal
to the excavation depth.
5.2.2 Installation next to trafficked areas (e.g. roads)
the named conditions for the excavations apply to all installation situa-
tions (the shallow variant has been illustrated here by way of example)
At least 1000 mm
distance from fixed
structures
Construction of slope (batter) or excavation supports from
1.25 m excavation depth, to DIN 4124
installation at a frost-free depth is required for all-year use
Installation of several tanks:
- the tanks can be positioned directly next to each other for a walkonable version
- a compacting space at least 40 cm wide must be left between the tanks for a trafficable version
Blinding layer, gravel, max. grading range 0/5 mm stone-free, compacted
> 200 mm
(walkonab-
le variant)
400 mm
(trafficable
variant)
Depending on
the installation
situation
Distance =
Excavation depth
Excavation depth
