The works were split into three drives in varying lengths. Working from 2.4 metre caisson shafts with trench sheets at a depth below 4 metres a 74-metre drive was installed before rotating the GAB machine and installing a 24-metre drive from the same caisson shaft. Following installation, the pipelines were connected in the drive shaft and fully tested in accordance with EN610.

The third pipeline required installation from another 2.4 metre caisson shaft at a depth of 5 metres which was required so the installed pipeline was 3 metres beneath a CLH pipeline (CLH-PS) fuel pipeline. To ensure that the ground movement beneath the CLH pipeline was inside the acceptable limits the pipeline had to be exposed and monitored by authorised personal wduring the installation of the jacking pipes. Following the installation of the jacking pipes the ground around the CLH pipeline was reinstated under supervision.

The ground conditions for the third drive changed to chalk with a high level of flint, water was added during the auger process which slowed the installation rate from 12 metres per shift to 5 metres. As installation progressed the full 18,000Nm of rotary torque was required, to rotate the flight augers in the hard ground encounted.

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Allen Watson Limited

Offices at:
- Horsham, West Sussex
- Harlow, Essex
- Barnsley, South Yorkshire

01403 790772

Case Studies

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