Construction World February 2018

PROJECT PROFILE

LOERIESFONTEIN and KHOBAB wind farms

C oncor Infrastructure was responsible for the construction of all 122 wind turbine generator foundations, as well as the adjoining hard stands and all internal roads on both sites. The company brought its extensive experience and expertise in civil engineering, concrete design and sustainable project management to these construction projects in a remote endemically sensitive and arid location. In planning and implementing its work, Concor Infrastructure was able to ensure a high quality product and service – with innovative cement-saving concrete mixes for the wind turbine bases – as well as water saving strategies and environmental care, all delivered well ahead of schedule. The environmental impact of the project was carefully considered and addressed through a number of integrated strategies. These in- cluded the conservation and recycling of scarce water resources, the bioremediation of hydrocarbons on site, relocation of protected plant species and an overall reduction in the project’s carbon footprint. Concor Infrastructure was also able to promote local employment and skills development in the area by sourcing much of its labour from the town of Loeriesfontein. In addition to the training provided, Concor Infrastructure mentored local small businesses to become effective suppliers and subcontractors. The company’s ongoing commitment to Zero Harm through strong health and safety practices allowed the projects to reach the 1,3 million LTIF (Lost Time Incident Free) milestone in January 2017. As at August 2017, the project was standing on 2 million LTIF for the Consortium. Loeriesfontein Wind Farm and Khobab Wind Farm are both part of the South African Government’s Round 3 Renewable Energy Independent Power Producer Procurement Programme (REIPPP). South Africa Mainstream Renewable Power has managed the construction and will manage operations of these wind farms, following commercial operations. Innovation Substantial innovation in concrete mixes was applied at the Loeriesfontein and Khobab sites, contributing to various environmental considerations while enhancing performance. The plinths at Loeriesfontein were constructed using high strength 60 MPa concrete with a design mix comprising 75% ground granulated corex slag (GGCS) in place of cement. As much as 95% waste replacement was used in the 12 200 cubic metres of 15 MPa concrete used for the blinding beneath the bases. Concor Infrastructure used 50% waste material for both the 60 MPa plinth concrete as well as the 30 MPa conical base concrete. Strengths were achieved at 28 days. Together, these initiatives reduced the wind farm’s construction carbon footprint from approximately 300 kg of CO 2 per cubic metre to 90,7 kg of CO 2 per cubic metre, Cape, are two pioneering renewable energy projects in which Concor Infrastructure played an important and innovative role. The wind farms were constructed by Concor Infrastructure in a consortium with CONCO. Loeriesfontein Wind Farm and Khobab Wind Farm, in the HantamMunicipality of the Northern

reducing the project’s estimated overall carbon footprint by 31%. Performance of concrete is vital for this demanding application. Each of the 122 wind turbine bases is 19 metres in diameter, and was constructed in the same manner to accommodate a 99 metre high turbine tower on which is placed a nacelle weighing in excess of 80 tonnes. The efficient, continuous work process allowed the construction of one foundation base – from excavation to completion – to take just 10 days. Corporate social environment Much of the workforce on both wind farm contracts was employed from the Loeriesfontein community 60 km to the south of the site, in support of local employment and upliftment. This is in line with Concor Infrastructure’s skills development strategy, as these workers needed specialised induction and training – and will also facilitate the sustainable development of the community. In addition to providing direct employment and skills develop- ment, Concor Infrastructure mentored several Enterprise Develop- ment initiatives, setting these up carefully to ensure their future sus- tainability even after the project construction had been completed. Transportation from Loeriesfontein to the project site could have posed a challenge and forward thinking from Concor Infrastructure saw the company assist a local resident of the town to start up his own transport business. In addition to purchasing a brand new Quan- tum mini bus to get the business started, the company also provided ongoing mentorship and training in the necessary skills that would be required to ensure a sustainable business model going forwards. Other enterprise development initiatives included a waste recycling operation, a woman-owned security company and a car wash facility in the town. Concor Infrastructure also ensured that existing local businesses were empowered and provided mentorship to these business owners as well. The company invested significant amounts of money and time in upgrading various community facilities including the local school and sports facilities. Significantly, even though the project has largely been completed, the investment in the local community is ongoing to ensure long term sustainability. Innovative design To reduce the project’s carbon footprint, carefully selected and treated waste material was used as a replacement for cement in low cement geo-polymer readymix concrete. The bases at the Loeriesfon- tein site contained a design mix comprising 50% ground granulated corex slag (GGCS). For the blinding beneath the bases, as much as 95% waste replacement was used in the concrete. 50% waste mate- rial was used for both the 60 MPA plinth concrete and the 30 MPa conical base concrete with strengths being achieved at 28 days. These design innovations had a profound impact on the project’s carbon footprint. While the carbon footprint of a standard 30 MPa concrete equates of approximately 300 kg to 350 kg per cubic metre, the reduced use of cement by these special mixes has helped dramatically reduce the wind farm’s carbon footprint to 90,7 kg of carbon dioxide per cubic metre. The wash bay comprised a series of settlement ponds, each having an overflow reporting to the next pond once it reached a certain level. Concrete sludge settling in the pond was removed manually and left on a specially constructed bunded slab to dry. Dried material was removed to the quarry site where it was crushed and blended with aggregate for reuse in the turbine bases.

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CONSTRUCTION WORLD FEBRUARY 2018