Higgins is carrying out all the civil works for the Project West Wind wind farm, scheduled to be completed by the end of next year, on behalf of the project’s owner Meridian Energy Ltd.
Work on the $400 million project started in November 2007, with the end result being a 62-turbine wind farm producing 143 MW of renewable energy – enough electricity to supply most households in the Greater Wellington region.
Currently there are four operational windfarms in NZ, two under construction, and two which have just received resource consent.
Despite Wellington’s windy reputation – it is located on the northern side of Cook Strait between the North and South Islands, which often funnels the full force of the Roaring 40s – this is the first wind farm being constructed in the region. At least another two sites are being investigated for future projects.
All NZ’s major power companies are currently investing in windfarms, with another half a dozen on the drawing board around the country.
According to David Rubery, manager of Higgins Contractors Projects Division, the company has had more experience in wind farm civil works than any other contractor – and the scale of the works is very substantial.
"Our responsibilities include earthworks, access roads, foundations for the turbines, trenching 60 km of trenches, and cable laying between the sixty-two 2.3 MW turbines, as well as substation construction and miscellaneous works," he said.
"All up, the civil works have about 1.2 million cubic metres of earthworks, 45km of road construction, plus about 24,000 cu m of concrete for turbine foundations which we’ll be batching on site, and we’ll be producing around 75,000 cu m of crushed rock – the majority which will be handled by the Komatsu crusher.
"This project is also unique in that we are trying to be completely self-sufficient in producing aggregate on site, so it doesn’t need to be trucked in," said David.
Cobus van Vuuren, manager of Higgins’ aggregates division, said the BR380JG-1 crusher is producing GAP 65 product, derived from river gravel and rock from excavated cuttings.
"We started on the crushing side of the project in December 2006, and [as of early March] we’re about 50% of the way through it," said Cobus.
"We’re very pleased with the BR380JG-1, it’s very well cut out for this kind of job.
"It’s a very mobile unit, and it’s economical to run. It’s crushing typical grey wacke, which is the predominant rock in the region.
"On this job, it’s a primary crushing application, bringing the rock down to 65 mm all-in product, which is what we need for the road base and the tower bases.
Quite separately to this project, Higgins recently bought two WA480-6 loaders, which are working at its aggregate production facility in Matai Road, Palmerston North.
"These two loaders working at our shingle plant, where we use gravel from a land-based source, crushing to material for road base and chip sealing," said Cobus.
"They are used to load the crushing plant, then carry the crushed product to stockpiles, and to load sales trucks.
"Since they were delivered late last year, they’ve been doing very well. They are economical to run and they are very comfortable machines.
"In this application, they do run around quite a bit; there’s a lot of load-and-carry work, which they are well suited to," he said.
"Both are fitted with 5 cu m buckets, which allows them to load most trucks in a single pass, so they can get them loaded and out of there very quickly.
"With the density of the product, each bucket load is between 8 to 11 tonnes, depending on the product. So after just one pass, most of the truck bodies are loaded to capacity," Cobus said.