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6. Sizing
The pit volume depends on the wastewater flow rate and the
pump performance.
If the liquid in the pit is static during long periods, sediments may
build up in the pit sump. The pump should therefore be started at
least twice every 24 hours.
7. Transportation and handling
When transporting and handling the pit at low
Note
temperatures, take into consideration that the pit
impact resistance is reduced.
Precautions in order to avoid damage to the pit during transport
and handling:
•
Do not dump the pit from the lorry.
•
Use approved straps of textile or similar materials when lifting
the pit on to or down from a lorry or moving it on the
construction site.
Handle and lift the pit according to local regulations.
•
When lifting the pumping station with a strap, use the ribs on
the pumping station.
•
Do not drag the pit over the ground.
•
Point loads must not occur.
•
The pit must not be exposed to sharp edges.
•
Fix the pit securely during transport.
•
When the pit is placed on the ground, make sure the ground is
even.
If the pit is equipped with a lifting point, use it
Caution
during handling.
Fig. 16 Lifting the pit
Support for the crane must be placed in a
suitable distance from the pit to avoid collapse of
Caution
pit hole.
Work according to local regulations.
Warning
Make sure that the lifting bracket is tightened
before attempting to lift the pit.
Tighten if necessary. Carelessness during lifting
or transportation may cause injury to persons or
damage to the pit.
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8. Installation
Warning
Installation of pits must be carried out by an
authorised person in accordance with local
regulations.
Work in or near wastewater pits must be carried
out according to local regulations.
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Fig. 17 Schematic installation drawing
Pos.
Description
1
Foundation layer
2
Bedding layer
3
Backfill, compacted in layers of maximum 30 cm
Distance of 50 cm from cover where heavy loads must
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not occur
The location of the pit must be selected so that
its installation does not damage other equipment.
Caution
And the other equipment must not damage the
buried pit.
Foundation layer
•
The pit must be placed on a foundation layer if soil analyses
and information about pit load indicate that the soil is not
capable of bearing the weight. The bedding layer on which the
pit is placed is not regarded as a foundation layer.
•
The foundation layer can be made after the excavation by
laying a stable layer of suitable gravel or similar material and
compacting it in layers of maximum 30 cm (corresponding to
approx. 20 cm after compaction). Such a foundation layer is
also required if the excavation has become too deep by
mistake.
Bedding layer
•
The material for the bedding layer must be compactable and
composed so that neither its properties nor the compaction will
cause damage to the pit.
•
Grains larger than 16 mm must not be present.
•
The content of grains between 8 and 16 mm must not exceed
10 %.
•
The material must not be frozen.
•
Sharp flint etc. must not be present.
•
The bedding layer must have a thickness of 10 cm.
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3
2
1
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