The 138 MW Jeffreys Bay Wind Farm in the Eastern Cape is characterised by the extremely fast track nature of the project. A consortium for the provision of civils and electrical infrastructure to one of the continent’s largest wind farm was formed by Murray & Roberts Construction companies, Concor Civils and Concor Roads & Earthworks, in joint venture with Consolidated Power Projects (Conco) with a contract start date of November 2012.
Murray & Roberts Construction’s portion of the project included the construction of 50 km of gravel road, 60 concrete foundations for the wind turbines, route modifications on the N2 highway and the building of an operations and maintenance building, as well as trenching for 200 km of MV cabling to the substation.
Each of the turbine foundations required approximately 335 cubic metres of concrete and the selection of a suitable cement supplier was based on a number of factors.
Globeleq is the majority shareholder and is jointly managing the construction of Jeffreys Bay Wind Farm. The company is an independent power industry leader in the emerging markets participating in nearly 14,000 MW of generation capacity in more than 25 countries. The project’s consortium partners include Old Mutual, Thebe Investment Corporation, Mainstream Renewable Power South Africa, Jeffreys Bay Community Trust, Enzani Technologies and Usizo Engineering.
The wind farm’s civils and electrical infrastructure consortium selected AfriSam’s HSC 52.5N cement due to its early strength properties. “The customer required cement that was not only able to provide the high strengths required for the turbine foundations, but that would also expedite the fast track construction programme due to its rapid hardening properties. This versatile cement is cost effective due to its workability, strength and durability properties,” Meredith Jordan, AfriSam sales manager: building, civil and manufacturing (BCM), explains.
“Delivery of the 4,000 tonnes of cement began in March 2013 and the last consignment was delivered in December the same year before the annual building and construction shutdown. The bulk of the product was sent from our Ulco factory, some 80 km outside of Kimberley. This equates to a lead distance in the order of 1,000 km each time we made a delivery. Our depots in Queenstown and East London were placed on standby as a backup and we were able to meet all our deadlines,” Jordan says.
The civils and electrical infrastructure project consortium was given ten milestone dates with which they needed to comply. Joe Nell, project manager for the consortium, says, “We were under extreme pressure but we have managed to meet the first nine milestones timeously and we are on track to achieve the final milestone in the first quarter of 2014. The seamless and expeditious delivery of cement by AfriSam has played a large role in the successful attainment of the turbine foundation deadlines.”
Murray & Roberts’ Concrete Centre of Excellence was tasked with developing the optimum concrete mix for the high temperatures generated beneath the turbines. The mix also needed to be extremely durable, so the concrete had a fair quantity of fly ash added to accommodate the demands of the end application.
“We established a concrete batching plant at a commercial quarry close to the project and the concrete was transported to various locations on this 3,800 ha site. It was critical to micro manage the interface with all parties, including AfriSam, Conco and Siemens, to ensure that the specified delivery periods were concluded without incident. Apart from the huge physical extent of the project’s footprint, at peak we had 650 people on site from the civil and electrical consortium and Siemens, leading to complex logistical planning,” Nell adds.
Nell points out that all the roads and the foundations are completed and the environmental rehabilitation process is underway. “A total of 97% of the cabling installation has been completed and the substation was energised on 6 December 2013. Siemens erected 70% of the turbines and the first two circuits were commissioned prior to the December 2013 shutdown. All component deliveries will be completed in February 2014 and the erection of the remaining turbines will be completed before the handover in April 2014.”