www.graf.info
22
/
48
6.
Installation and assembly
6.2.6 Insertion and filling
The shafts should be carefully lowered into the
excavation avoiding any sudden jolts.
The shaft must be filled 1/3 full of water before
commencing the back filling. The back fill should
be carried out using 8 to 16mm single sized gravel
and compacted in 30cm (max.) layers until the top
of the shaft is reached.
The individual layers and the lower zone of the
shafts must be well compacted
(with a hand tam-
per). Be careful to avoid damaging the shafts when
compacting
the gravel. Mechanical compression
machines must never be used. The trench sur-
round must be at least 300 mm wide.
Please note:
It is especially important for the filling in the bottom third of the shaft to be well compacted
1. 1/3
2. 3/3
>300