Geotechnical design of the Те Apiti Wind Farm

Recently built Те Apiti Wind Farm, the largest in the southern hemisphere and New Zealand's newest, feeds up to 90 MW into the national power grid from the 55 1.65 MW turbines (each 106 m high) built on the north side of the Manawatu Gorge, near Palmerston North City. Те Apiti is located on 1200 hectares of undulating hill terrain. Steep eroded gullies and numerous active landslide scars expose an uplifted and tilted marine sequence of Tertiary rocks. Site investigations were undertaken to assess the stability of the wind turbine platforms and to provide information for the design of the access roads and the turbine foundations. The turbines were founded on 16 m to 18 m wide octagonal shallow pad foundations. Geotechnical investigation and design issues are discussed.