This work was required to tie in energy generated by the new White Rock Wind Farm, into TransGrid’s network. The wind farm is owned by CECEP and Goldwind, and this first stage of the wind farm consists of 70 turbines that will produce 175 MW of electricity annually.
The biggest hurdle Zinfra faced from the outset of the project was an accelerated schedule. The original delivery timeframe of 35 weeks was shortened by 90 days: that’s a 35% reduction before work even began.
As a national company, with extensive resources, Zinfra was able to mobilise extra resources to site in a short time frame to meet this accelerated delivery schedule. Electricians, linesman, testing and commissioning employees and their support team were brought in to expedite works.
Civil works for the substation site were planned in such a way that the different site areas were delivered in stages in order for Zinfra to commence electrical construction while civil works continued concurrently.
The weather at White Rock Wind Farm is highly changeable and can be wet and, obviously, windy. Wet weather however proved the greatest nemesis for this project. A single day of rain could lead to two weeks of down-time as wet, muddy and slippery conditions made heavy machinery use impossible.
The civil team prepared the substation site to mitigate the risk of down-time from rain. They graded the site well and put down sheeting to assist with run off, and facilitate a fast return to work for the construction teams after rain.
Access in steep, rocky terrain
Access on the site, which extends over a 10 kilometre range, was via a single road on which all contractors had to travel. Constructed for the project, the road was subject to the vagaries of wet weather, the landholders’ livestock and the frequent oversized deliveries of turbine blades and parts.
The eight kilometre dual circuit transmission line runs from the existing TransGrid network at the bottom of the site location. The line includes two long spans – one 600 metres and the other 900 metres – to breach deep ravines along its path.
The steep terrain and wet conditions meant getting in to clear an easement and erect the 47 transmission poles over 30 sites was no mean feat.
Safety on site
Safety on site was a non-negotiable, though, on a project of this scale there are always challenges. Teamwork was critical on this site. With crews having to change in and out regularly because of weather delays. Good communication and the ability to absorb change were important.
Transmission pole erection
The erection of the final two dual circuit transmission poles had to coincide with a one day outage scheduled by TransGrid.
Stringing of the cables was expedited by the use of helicopters. After extensive preparation, risk mitigation and safety controls were implemented, helicopters successfully strung approximately 26 kilometres of cable and OPGW over three days.
Project success was attributed to the people on site who put in hard work to overcome the challenges on this project, along with strong collaboration between Zinfra and its key stakeholders, TransGrid and Goldwind, and the many contractors on site.
Throughout the project a consultative approach, coupled with Zinfra’s extensive network and electrical knowledge, led to improved construction methodologies for TransGrid.