Tararua Stage 3

The Tararua wind farm, built in three stages, and located at the northern end of the Tararua Ranges, near Palmerston North, is the largest in New Zealand.

Our geotechnical and civil engineers were commissioned during Stage 3 to provide:

• A comprehensive geotechnical assessment of the foundation conditions and requirements for each of the 31 3MW turbine locations.

• Slope stability analysis and upgrading for a 25km roading network, taking into consideration a 30,000m3 gully fill.

• A geotechnical assessment, including slope stability analysis of the proposed disposal areas.

• An earthworks management plan outlining measures to control erosion, sediment runoff and dust.

Time was an important factor. It was necessary to have early identification of the suitability of the foundation system for each turbine site, and possible foundation alternatives, in order to organise drilling rigs at a time when the industry was at its busiest.
Many of the proposed turbine sites are located in remote areas with access only possible via quad bikes or 4x4 vehicles. The sites are near or adjacent to moderate to steeply sloping ground.

Whilst the stability of the turbine sites and the foundation requirements was a high priority, the assessment of the stability and engineering requirements for the new roads, road widening and aggregates also received significant focus. Much of the proposed area for the siting of the new turbines is remote and no road system existed. The new roading system needed to be carefully designed to accommodate the 47m long transportation vehicles. Civil construction included approximately 450,000m3 of earthworks.

Continued involvement includes reviewing monitoring data and undertaking civil inspections.

 THE OUTCOME 

Successful completion of access roads, construction platforms and turbine foundation excavations.