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Backfill
•
The backfill must provide sufficient support of the pit on all
sides and ensure that the load can be transferred without
detrimental point impacts or similar impacts.
•
The backfill must meet the same requirements as those for the
bedding layer.
•
Backfilling must be carried out so that the pit is not damaged
or deformed.
•
The backfill must be compacted in layers of maximum 30 cm
(corresponding to approx. 20 cm after compaction).
Warning
Before the pit is lowered into position, various
connections must be retightened, as they may
have become loose during the transport.
Check the pit for external damage before
lowering it into position. When the pit has been
Note
installed, Grundfos cannot be held responsible
for possible damage.
Place the pit on the bedding layer.
Check that the pit is vertical.
Groundwater must not rise above the bedding layer until
backfilling has been completed.
Compact the backfill under the inlet and outlet
pipes properly so that they are not exposed to
Note
downward loads when the backfill settles.
See fig. 18.
Fig. 18 Insufficient compaction under pipes
During backfilling, the cover must be fitted on the
Note
pit to ensure that the pit is not deformed
(becomes oval).
Fig. 19 Oval pit after compaction
2
If the hole for the pit is drilled, pay special
Caution
attention to the compaction of the backfill to
prevent uplift.
1
1a
Use mechanical compacting equipment and
Caution
compact the backfill to 98-100 % proctor density.
Uplift prevention
•
The pit design ensures that the pit is protected against uplift if
installed correctly. Requirements for uplift prevention depend
on the geotechnical conditions. They should be determined by
the engineer/contractor and are outside Grundfos' area of
responsibility.
The above requirements are minimum
Caution
requirements. Observe local regulations.
8.1 Installation of valve chamber
When installing the valve chamber, follow the same instructions
as for installation of the pit. See section
The valve chamber is only to be installed for
Note
PS.R.17 pits.
Isolating valves
Non-return valves
Fig. 20 Valve chamber
Max.
25 kN
Max.
150 kg
8.
Installation.
9
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