Project West Wind is a wind farm development just off Oteranga Bay in New Zealand. Located on the southern tip of New Zealand’s Northern Island, the wind farm – to be the largest in the country when it comes on line next year – will be able to power 110,000 homes in the town of Wellington.
For this project, Griffiths Drilling Ltd. had difficult terrain to contend with, as well as very fractured rock, due to the close proximity to major fault lines. Compounding this were the very high winds and extreme weather conditions in which the crews were operating.
For the wind farm development, Griffiths drilled more than 30 holes across the site on the ridgelines where the turbines were to be sited. Further bores were drilled for the wharf structure on the beach at Oteranga Bay, where the submarine power cables come ashore, and other investigations, including inclined cored holes for suitable quarry material, were carried out across the site.
For the transmission line segment of the endeavor, Griffiths carried out a number of holes at possible tower locations to assist with design of a new transmission line to carry the power from the wind farm to the national grid.
Limited access, steep terrain, wet slippery conditions and very high winds all were complicating factors to overcome. The rock was very fractured due to the proximity of the main fault line, and required the skills the firm has developed in working with Wellingtons’ difficult ground conditions to successfully core the highly fractured weathered greywacke.
For the transmission line project, no new roading across the steep terrain could be constructed, meaning careful planning and complicated logistics were needed to get to the proposed tower locations. For example, some sites required scaffolding to fly the gear onto, due to the steepness of the terrain.
One of the drilling contractor’s helicopter-portable units was used to reach the bore locations high up on the hillside that were only accessible by air. Due to the proximity of the national grid, safety of both the network and all personnel was paramount, and required meticulous planning before getting off the ground. This was made easier by the helicopter operator, who routinely flies maintenance crews on live line work in and around the lines.
Griffiths Drilling, established in 1971, is a Wellington-based operation, specializing in geotechnical, exploration and construction projects throughout New Zealand and the surrounding islands. Its experience encompasses some of the largest, and most technically challenging drilling projects in New Zealand.