Wairakei Diversion

Wairakei Diversion

This project for McConnell Dowell involved completing two sections of the Wairakei Diversion under the Wairarapa Stream, which meanders its way through the suburb of Fendalton.

The stream had to be maintained in a clean and risk-free environment.

Johnston Civil used their sheet-piling crews to form temporary barriers and dewater the immense ground water installation from the Riccarton gravels below the invert of the stream bedwhich was approximately 1.5 metres.

The connection on to the live main proposed challenge to connect while the trunk main flows were too great to over pump, so a flume system was created by Johnston Civil engineers to provide flow whilst creating a benched connection. This ensured one of the City’s main trunk sewers was flowing uninterrupted whilst the connections and construction was successfully completed to the satisfaction of the client and the main contractor.