Massingir Dam is a 48 m-high, 4.8 km-long embankment dam on the Rio dos Elefantes in Gaza Province, Mozambique. It has a major socio-economic impact on communities using water from the dam for domestic, irrigation and other purposes.
Less than a year after its construction in 1977, the Massingir Dam started displaying major distress defects. Following the installation of crest gates to raise the full supply level of the dam, a sudden failure of the outlet conduits in May 2008 resulted in an uncontrolled discharge of approximately 1 000 m³/s of water to the downstream area, threatening the structural safety of the dam.
Zutari was appointed to assist in the rehabilitation of the dam by investigating the cause of the failure of the bottom outlet as well as investigating alternative methods of reinstating the bottom outlet. Zutari also prepared detailed designs and tender documentation and undertook a comprehensive safety assessment of the dam.
The rehabilitation works comprised the installation of 6.4 m diameter steel liners into the existing 8 m diameter reinforced concrete (RC) outlet conduits, infill concreting and grouting, and the rehabilitation of the downstream radial gates, including an entirely new hydraulic actuator system.
Other work on the dam included the construction of large diameter pressure relief wells, installation of supplementary dam safety instrumentation and crest lighting on the earth fill embankment and the supervision contract also included a new water supply for the town of Massingir and other minor works.
Less than a year after its construction in 1977, the Massingir Dam started displaying major distress defects.
Zutari’s cost-effective rehabilitation method dealt with safety concerns and at the same time restored the dam to full functionality.
Reinforcement detailing defects in the original design combined with pore pressure within the concrete appear to have triggered the failure. Pore pressure should be considered when designing RC pressure conduits, particularly in cases like this where water is under pressure on both sides of the dividing wall.
Zutari’s cost-effective rehabilitation method dealt with safety concerns and at the same time restored the dam to full functionality.
“We are proud of our contribution to reinstating the dam to full serviceability through safe design, and ensuring sustainable water supply to communities and the
*The Aurecon Africa business has been officially renamed Zutari as at 21 July 2020. Zutari acquired Aurecon Middle East on 20 November 2020.
