Hammanskraal, Bulk 3, Pipe Jacking, 148.840 m, 2015

Pipe jacking is a specialist tunneling method for installing underground pipelines with the minimum surface disruption. Primarily used for new sewer construction it is also used for sewer replacement and relining, water mains and pipelines installations.

Construction conditions are extremely difficult as this new line runs alongside the Hammanskraal dam which results in unstable soil conditions and continuous seepage of ground water through the soil into the excavations.

The construction process had to be altered to allow for continuous water pumping and the import of stable material for construction. Hard rock in trench excavations was encountered all along the pipeline. A portion of the pipeline needed to be constructed that crossed underneath a dam wall close to a main Eskom Power line by means of Pipe Jacking. The Pipe Jacking is 149m Long and 5.9 meters deep, and it allows the pipe line to cross these obstacles undisturbed.