The Southern Pipeline is a large wastewater pipeline that is needed to transfer sewage from Tauriko/Greerton to the Te Maunga Wastewater Treatment Plant. It will also take away a lot of the pressure from the rest of the City's wastewater system.
The project involved four trenchless crossings under motorway, rail and high voltage power lines. A combination of temporary works and trenchless pipe installation solutions were employed to complete the project.
One of the key constraints of the project was constructing the sheet piled launch shaft for the Pipe Hammer drive in a stormwater detention basin. Careful planning, and construction of temporary platforms permitted the safe construction of the 20m long launch shaft, and subsequent successful installation of the hammer drive under state highway 29.
The remaining three shafts were constructed using soldier piles and timber lagging, and were pipe jacked by hand excavation. Due to the weak ground conditions, continual monitoring was required for the rail lines to prevent any settlement.