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DECEMBER • 2016
Construction
WORLD
28
Civil Engineering and Building Contractors (outside South Africa)
A
3
KASANE-KAZUNGULA VILLAGES
SANITATION PROJECT
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
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
• Mechanical subcontractor: Pumpco
• Electrical subcontractor: Chronos
• Project value: R586-million (approximately)
Winner