Isthmus

Room to breathe.
Waitahora
Wind Farm.

Approach

Consideration of landscape at all scales was the driving principle behind the design of Waitahora, a Contact Energy wind farm project given consent in 2008. The site is on the Puketoi Range, a distinctive cuesta east of Dannevirke, toward which wind is funnelled from the saddle between the Tararua and Ruahine Ranges.

Below The wind farm is located on a broad ‘dip slope’, set back from the escarpment ridge and landmark peak of Oporae. Numbers on the map represent the proposed positions of turbines.

You can’t hide a wind farm. They are prominent because of the size of their turbines and the requirement for windy locations – which means open coast or high inland ranges. At Waitahora, as with all wind farms, choosing an appropriate location and layout for the wind farm was of prime importance. The Puketoi Range is an ‘outstanding natural landscape’ – a ‘cuesta’ characteristic of the east coast of the North Island, significant to Rangitāne and a backdrop for the Waitahora farming community.

Above Diagrams illustrate the positioning of wind turbines so there is a clear figure–ground separation between the wind farm and the underlying detailed features.

‘Appropriateness’ of the wind farm was a question of location and design. With regard to location, the wind farm was designed to fit the broadest area of dip slope at the northern end of the range. This was considered the most appropriate location because it confined the wind farm to a discrete section of the range while allowing a viable number of turbines. The turbines were set back several hundred metres from the most distinctive elements: the escarpment ridge and Oporae – a landmark peak which acts as a full stop at the northern end of the range. The layout allows these elements room to breathe.

At a finer scale, the Puketoi Range comprises distinctive limestone features, so the civil engineering and wind turbine locations were fine-tuned to avoid these and to minimise the impacts on the karst landscape as a whole. Avoiding fine-scale natural features allowed the land surface to remain legible despite the height of the turbines, the size of which was a contentious design issue.

Below Elevation and slope angle diagrams illustrate that the wind farm avoids the highest points and steepest slopes. Rather it is located on the broadest area of the dip slope, highlighting the ‘cuesta’ landform; a cuesta landform comprises a hill or ridge with a gentle backslope on one side and a steep face on the other.

As there were no examples of large, 150-metre-high turbines in New Zealand at the time, Isthmus researched wind farms in Sicily, where 150-metre and smaller turbines are co-located. That study showed the difficulty in perceiving differences in size where objects have generic shape, such as wind turbines, and are of such a size that normal scale references no longer apply. It demonstrated that the scale relationship is with the horizontal landscape rather than with small vertical features such as trees and buildings, and that in contexts where there is a bold landscape, such as Waitahora, it is better to have larger and fewer turbines compared to a more cluttered array of smaller turbines.

Team Members
Gavin Lister, Alan England,
Past Team Members

Emma Golightly, Grace He, Kent Lundberg

Consultant Team
EMS – Stephen Daysh (planner)
Trevor Robinson (barrister)
Buddle Findlay – David Allen (lawyer)
Auckland University – Prof. Paul Williams (geology and geomorphology); Prof. Richard Holdaway (paleoecology);
Boffa Miskell; Dr Vaughan Keesing (ecology)

Client
Contact Energy Limited