Werbung
1.5 Installation Details
In clay ground conditions: 1.75-m depth of the excavation (picture 2 and 13a under point 3) no
angle of repose necessary. The excavated area should be wide enough so that compression of the
filling material is possible (200 in picture 2 under point 3). With installations deeper than 1.75 m
an area of 500 mm is necessary; the tank should be covered with at least 300 mm thick with
filling material (picture 13a under point 3).
With loose grounds (coarse sand, gravel) the above information is valid for 1.25-m excavation
depth.
Also with excavated area widths of 500 mm, in the pictures from 3 to 12 as well as 13a, shown
installation steps are valid.
1.6 Further criteria
Existing pipelines, pipes, vegetation as well as other specifics have to be considered, so that
damage or hazards will be avoided. The soil coverage from the tank shoulder (point 4) may be up
to a maximum 1.0 m.
TIP!
It is possible to maximise the volume by using a customary nozzle. The pipe bend should be
87.50 and the overflow mounted upwards.
2. Installation
2. 1 Backfill material at the tank (backfill, bedding; point 3 figures 3, 4 and 10)
The backfill material has to be well compactable and permeable to water, allowing a close packing
and no damage the surface of the tank. If the filling material contains sharp or sharp-edged
components, the wall of the tank has to be protected by a sandy coating.
2.1.1 Sand - gravel mixtures (SW and GW to German Institute for Standardization 18196 and
ENV 1046) are the most favourable filling materials, because they have a grain line which
consists of several grain sizes with only a low amount of fines (fines: under Ø 0,06mm). At the
description of the mixtures the first number gives the mesh width (simplified Ø) of the smallest
grain and the second one those of the biggest grain: e.g., 0/32; 2/16; 2/8; 2/32; 4/16. Which
mixtures are available, strongly depends on the regional supplies.
2.1.2 Grit is broken rock of the grain range of 2/32 and basically is suitable as a backfill material;
but because of its sharp edges the tank must be protected against damages, e.g., by a sandy
wrapping.
2.1.3 Excavation, sand and gravel mixtures with an irregular grain line are suitable as backfill
material if they correspond to the criteria under point 2.1.
2.1.4 Soil, loam or other cohesive soil conditions are not suitable for the backfilling.
2.2 Filling beyond the backfill
Excavated soil (point 3 figures 1 and 10) or other material can be used if this is stable and
permeable.
2.4 Pipes
2.4.1 The feed pipe should be laid with a fall to the tank (>1%).
2.4.2 The overflow / drain pipe should have a deeper fall away from the tank than the fall from
the feed pipe to the tank.
2.4.3 The service pipe is to be installed to prevent any flooding from the tank entering the
service room (e.g., cellar) if the tank is full. This can be achieved, for example, by a high enough
incline of the pipe from the house to the tank. Or by the installation of a seal.
2.4.4 The pipes have to be installed in such a way that frost damage is avoided. This is to be
arranged according to the local climatic circumstances, if necessary in co-ordination with the local
authorities.
DORW1009
10.01.2012
4 / 16
Werbung
