Construction World April 2017

WASTE MANAGEMENT AND RECYCLING

INNOVATIVE environmental INITIATIVES

Situated close to the Helios substation in the Hantam Municipality, when completed these two wind farms will boast a total of 122 wind turbine generators between them and each will feed 563 500 MWh of clean renewable energy into the national grid. The Loeriesfontein Wind Farm and the Khobab Wind Farm were constructed by Murray & Roberts Construction in a consortium with CONCO. Significantly, the two companies also successfully completed the construction of the Noupoort Wind Farm for operator, Mainstream Renewable Power South Africa. An arid region “Constructing such important projects in Murray & Roberts Infrastructure on the Loeriesfontein Wind Farm and Khobab Wind Farm project in the Northern Cape. An innovative approach saw several impressive environmental initiatives implemented by

this remote location called for innovative thinking on our part,” Stephan Venter, project manager for Murray & Roberts Infrastructure, says. Boesmanland in the Northern Cape is an arid region, which has been further exacerbated by the grips of a severe drought making the availability of water a major challenge for all. As a result of this major water scarcity, limited extraction rates were allowed in the Water Use Licences. Venter says that the water shortage and low extraction limit was taken into account by the Murray & Roberts Infrastructure team, and an intense water management plan aimed at reducing water consumption was put into place. Marli van Rooy, environmental officer for Murray & Roberts Infrastructure on the project, says that the main strategy was to reuse as much of the water under the company’s control as possible as this would reduce the need to source additional water supply. As part of the initiative, Murray & Roberts Infrastructure installed a modular water treatment plant on site. The plant has a screening system which removes

the heaviest solids, while bacteriological rollers treat the remainder. Significantly, no chemicals are used during the process. “Having the plant allowed the treatment of grey and black water generated on site and the reuse of this recycled water for construction purposes,” Van Rooy explains. Majority of the recycled water was used on the earthwork layers for the wind turbine bases. On average, the treatment plant cleaned 30 000 litres per day and the treated water was stored in two reservoirs for reuse. Another initiative aimed specifically at reducing water consumption was the construction of a specialised wash bay solution at the on-site batch plant. “Wash- ing the drums of readymix concrete trucks is a necessity on any construction site, but wasting water is not,” Van Rooy explains. The wash bay comprises a series of settlement ponds, with each having an overflow which reports to the next pond once it reaches a certain level. The concrete sludge settles in the pond and once this happens it is removed manually and left on a specially constructed bunded slab to dry. “This resultant dried material was removed

Marli van Rooy, environmental officer for Murray & Roberts Infrastructure, outside the modular water treatment plant installed by the company.

“On a site as remote as this, soil contamination can be an extreme challenge as there are further complications including the distances to the nearest hazardous landfill site which is in Cape Town.”

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CONSTRUCTION WORLD APRIL 2017