The construction of a wind farm in Jeffreys Bay, in the Eastern Cape, was completed in May, with the 60-turbine 138-MW-a-day plant expected to supply renewable electricity to power about 115 000 homes at full capacity, project civil and structural works designer and South African arm of engineering consultancy WorleyParsons, reports.

In November 2012, South African construction firm Murray & Roberts awarded WorleyParsons the civil and structural works design for the construction, a first of its kind in South Africa.

“The Jeffreys Bay wind farm is one of the first full-scale wind energy projects to be constructed in South Africa, and WorleyParsons was very excited to be directly involved,” says project lead and WorleyParsons Port Elizabeth manager Willem Hofmeyr.

The scope of work included the design and quality control of access roads, concrete foundations for the wind turbines, geotechnical verification and modifications on the N2 highway for the wind turbines to be transported from the Nqgura Deep Water Harbour to the site.

The development stretches across eight farms, covering an area of over 3 000 ha. The wind turbines have a hub height of 80 m and a 110 m rotor diameter. Each turbine is supported by a reinforced concrete foundation.

Other key components of the project included gravel surfaced hardstand areas adjacent to each turbine, a substation, a single- storey operation and maintenance building, a permanent wind measuring mast, 50 km of gravel surfaced roads to provide access to the turbines and substation from the existing public road systems, and temporary facilities to serve as a construction site and lay-down area for the assembly of the turbines.

“Designing wind farm access roads and turbine foundations is a first for WorleyParsons, and a number of new principles had to be investigated and mastered. We are proud to have set new industry benchmarks for a project that is one of the first of its kind in South Africa,” explains Hofmeyr.

The contract used joint expertise across WorleyParsons’s regional offices in Port Elizabeth and Pretoria, assisted by WorleyParsons’s global renewable energy division. The civil works were executed by the local office in Port Elizabeth, while the structural design for the concrete foundations was undertaken by the Pretoria office, with the assistance of Denmark-based specialist designers COWI which has designed more than 12 000 wind tower foundations.

Despite a number of challenges, including role-players scattered across the country and globally, complying with strict project specifications application from suppliers, and tight timeframes, the project progressed well, with zero lost-time injury, reports Hofmeyr.

The operational life of the turbines is expected to be a minimum of 25 years.