Construction World December 2016

Winner

Civil Engineering and Building Contractors (outside South Africa) A 3 KASANE-KAZUNGULA VILLAGES SANITATION PROJECT

logistical constraints, the contractor was granted a four month extension of time, while all other client deadlines were met on time and the project completed within budget. Originality and engineering excellence was displayed both in the design of the new sanitation system and its construction methodology. Various sanitation system options were considered including the more traditional pumped waste transportation. Despite the lack of experience in Africa with vacuum-based systems, Aurecon designed an innovative combined gravity and vacuum solution that was more economical and practical for the topography and required transportation distances in the project footprint. Supply of a system from Europe was ruled out on the basis of cost. Therefore, Aurecon undertook the design and arranged for the local manufacture and procurement of all components. The existing sanitation system was inadequate for this tourism hub and commercial transport link with Zambia, resulting in frequent contamination of the Chobe River and causing significant health concerns among local communities. The project’s vacuum- based collection and transportation system is working flawlessly and has achieved the objective of creating a significantly healthier local environment. To eliminate the potential for sewage odours from vacuum stations and collection chambers, simple bio-filters were designed and installed using a bed of stones and eucalyptus chips. Indigenous trees were used to screen system installations. A preferred pipeline route was also replanned to bypass a large baobab tree. The stations in the new scheme are fully automated and transport the sewage in a closed system with minimal risk of spillages into the Chobe River. Protecting such an ecologically sensitive area, by designing the highest quality sanitation scheme, will ensure the sustainability of all ecosystems. Initiated in March 2012, practical completion of the project was achieved by 5 October 2015. Ground rehabilitation and general aesthetics was completed by subcontractors in April 2016. This was a noteworthy accomplishment for a unique project carried out in a challenging remote location. The main contractual deadline was met in spite of a legal land dispute delaying establishment of the project’s lift station for six months and the contractor having a four-month delay as a result of supplier delivery overruns. Project information • Company entering: Aurecon • Client: Botswana Department of Wast Management and Pollution Control • Start date: 20 March 2012 • End date: 5 October 2015 • Main contractor: Unik Construction Engineering • Geotechnical subcontractor: Material Investigation Centre • Project manager: Aurecon • Consulting engineer: Aurecon

An innovative vacuum-based system was the highly successful solution for the Kasane- Kazungula Villages’ Sanitation Project to improve the sanitation system in this northern part of Botswana, close to the Chobe River and the border with Zambia. The existing sanitation services were typically septic tanks or small and inefficient treatment works, which were continually overflowing and contaminating the river, causing health concerns for the estimated 30 000 residents of the villages and over 250 000 tourists a year. Aurecon was appointed by the Botswana Department of Waste Management and Pollution Control to provide strategic design input including an inception report, preliminary design report, and final design report for a new sanitation system. The company’s responsibilities also included preparation of construction drawings and tender documentation. During the inception report stage, Aurecon mobilised the project by collecting data, producing a detailed programme of the required work and conducted the necessary surveys and investigations. The preliminary design report also involved lengthy consultation with stakeholders to motivate community participation. The topography of the two villages presented challenges for a traditional gravity line and lift station design. To overcome this, Aurecon developed an innovative vacuum system to collect and transport the sewage. The concept is used in Europe, but the technology is new on the African continent. The final design is believed to be the largest vacuum system of its kind in the world and consists of five vacuum stations and 50 km of vacuum pipe. The system’s vacuum pots were designed in Botswana by Aurecon and fabricated in South Africa. Construction used an advanced electrofusion method to weld the vacuum pipelines. Aurecon’s strategic design provided the innovative engineering solution for a hygienic sanitation system to serve the various communities in Botswana’s Kasane-Kazungula region. Due to

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• Mechanical subcontractor: Pumpco • Electrical subcontractor: Chronos • Project value: R586-million (approximately)

Construction WORLD

DECEMBER • 2016