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Te Uku near Raglan, Meridian Energy’s latest wind farm, is ahead of schedule thanks to its close working partnership between developers and contractors. BY ALAN TITCHALL.
Although it features only 28 turbines, the site covers over 55 square kilometres and involves some 23 kilometres of new roads. The site is also a working sheep and cattle farm at heights of over 400 metres above sea level, so the civil works were always going to be challenging. The wind farm’s name, Te Uku, is also a reference to the region’s red, claggy, clay, which turns into a slippery glue when wet. It was the soil types that presented the biggest challenge for the wind project, both from an environmental perspective and the logistics of building 23 kilometres of road through steep grades and ravines over a short construction window. “The soil conditions at this site are some of the most challenging our contractors have ever had to work with,” says Meridian’s Te Uku project manager, Robert Batters. “It only needs to get a little water on it and it turns into a slippery slush, so erosion and sediment control was a key environmental management focus from the start, as was managing the very dangerous working conditions, particularly at the start of the project.”
“Then we got some of the worse weather conditions the region has ever experienced during that time of the year and one of the wettest Februarys on record,” says Batters. “To secure approval from Environment Waikato for the project we had to demonstrate that we could continue to meet the strict consent conditions if bulk earthworks were to be undertaken over the winter.” Despite the weather, and even the dangers – the site had to be evacuated a couple of times through February due to poor weather, roading was completed in time and the construction of the 28 turbine foundations remains ahead of schedule. “Luckily, we managed to avoid undertaking bulk earthworks in the restricted period as we had excellent weather during March and April. We even managed to get about four, to six weeks, ahead of programme in respect to the construction of turbine foundations.” A unique partnership
Other partners in the project sharing the site office in Raglan are Siemens NZ, who are supplying and installing the turbines; WEL Networks, who is building the 26 kilometre transmission line from the wind farm to the Te Kowhai and Te Uku sub stations; Transfield Services, who are performing on site electrical works; and NZ Cranes, who will erect the turbines. “We refer to our partners as ‘our construction team’ as we have worked collaboratively together and under one roof. This makes sure we are communicating effectively and making decisions quickly as a team. The ‘one team’ concept is something people talk about particularly during the tender phase of a project but doesn’t often eventuate, but here it does.” Batters suspects the contracting industry was surprised that Meridian chose two smaller-sized civil contractors for the project rather than one of the ‘big boys’. “We felt Hicks/Spartan JV offered us a lot in terms of the practical experience their people would bring to the job. Plus they allow us to run a very flat management structure between my role as project manager and the guys on the tools who in some cases are the owners of their business,” he says.
It’s an arrangement with cost benefits by providing an effective way of communicating and making decisions very quickly as a team, he adds. “Because of the project’s timeframe, construction decisions had to be made quickly – we just didn’t have a week to think about things.” This approach to contracting is a different approach from that used on some of our previous wind farm projects, says Batters. “It represents a major shift for our organisation and introduces other operators into the wind farm civil construction market who have demonstrated that they are more than capable of doing a very challenging job.” FoundationsAt the time of Contractor magazine’s visit to the site, 23 foundations had been finished some weeks ahead of schedule.
Spartan used a laminated reinforcing mesh permanent formwork system (an alternative to timber/steel formwork) to speed up construction and reduce costs. “We did look at using pile foundations on this job but there are a lot of boulders throughout the site,” says Batters, adding that the form work system used at Te Uku will be used for Meridian’s future wind farms. Heavy haulage challengeRoading was consented at 10 metres wide, however the bulk earthworks were reduced in scale by making the primary spine road just six metres wide, and the secondary roads and an average of 4.5-5 metres wide. The narrower roads were achievable through the use of narrow-wheeled cranes for the tower erection.
These turbines are fitted with 49 metre blades, presenting its own heavy haulage logistic problems along a fairly challenging route. “There are two bridges at Te Mata and a pedestrian bridge at Huntly that we have had to manage,” says Batters. “We have managed to configure the transport vehicles so that the tower sections can go under the Huntly pedestrian bridge, while the blades are currently planned to come down the western side of the Waikato River after turning-off at Rangiriri.” The company completed a number of trial loads along the narrow, twisting road that peels off State Highway 23 to the site at Te Mata. “We will need three or four prime movers to pull some of the equipment up steep hills on site,” he says. A 300-tonne crane will be used to erect the base of the towers, which are secured onto their foundations with 160, 1.5 metre bolts. A large, Terex-Demag TC 2800 wheeled crane, one of the largest mobile cranes seen in New Zealand (with a lifting capacity of 600 tonnes) will finish the job by early 2011 (weather permitting), which is at least six weeks ahead of schedule. “When we arrived here, the view was that the project would take two summer seasons to complete the civil works and even some who tendered for the civil works didn’t think it could be done in one season. Our construction team has certainly surprised a lot of people in the civil industry and it demonstrates the value the likes of Steve and Bob Hicks have brought to the job,” says Batters.
Contractor Vol.34 No.8 September 2010 |
Meridian raised a few industry eyebrows when it selected a joint venture between Hick Bros Civil and Spartan Construction, instead of one of the ‘big five’, to build its latest and most challenging wind farm project on the precipitous ridges surrounding Te Mata near Raglan in Waikato.
Because of the region’s soil types, Environment Waikato does not usually allow bulk earthworks to be undertaken over the winter period. Permission to continue bulk earthworks beyond April was based on guarantees from Meridian as to its environmental management practices. Works started in November 2009 with construction going well until late in the summer.
The civil construction team did an “outstanding job under the conditions”, says Batters. By July this year the concrete/aggregate mix roading and pavement was in place and 23 of the 28 turbine foundations were poured, with works carried out by the Hicks/Spartan joint venture.
“Take Bob Hicks, 70 years of age and still on the tools. You couldn’t put a dollar value on the experience he has brought to the project.”
The foundation design is a massive (up to 18.5 metres wide) ‘gravity’ type pad. The concrete platforms are up to 2.25 metres deep and constructed with reinforced steel and up to 471 cubic metres of concrete produced at the onsite concrete batching plant. The plant was brought in by Allied Concrete from Hampton Downs Raceway and re-erected on site in 10 working days on site. An existing quarry, owned by one of the four land owners (Tom Jowsey), was upgraded within eight weeks enabling the quarry to increase production from 20,000-30,000 tonnes per annum to over 200,000 tonnes of aggregate for roads and foundations over a 10-month period.
The next stage (beginning in September 2010) is the transportation of the 80 metre Siemens turbine towers (in three sections), blade sets and components from the Port of Auckland.