Massingir Dam : A premiere in Mozambique

Rehabilitation of Massingir dam was driven by the construction of a massive auxiliary spillway. Excavated within the dam’s embankment, the auxiliary spillway is controlled by 14 Fusegates, 5.80 m high by 10.85 m wide.

Massingir Dam lies about 300 km north of Maputo city (Gaza province), right at the border with the Limpopo National Park. Its 4.5 km long earthfill embankment structure retains the water of the Olifants river, primarily for agriculture and flood protection purposes.

Following the extreme 2000 floods, the National Directorate of Water (DNA) launched studies to assess the safety of the dam. Results highlighted its vulnerability as the service spillway was unable to pass the flood. The client’s engineer advocated the use of Hydroplus® Fusegates to equip the auxiliary spillway instead of a fuse plug design. Fusegates were favored for their long term durability, inherent safety and minimal maintenance.

Fourteen cast-in-situ Fusegates, 5.80 m high by 10.85 m wide, span along the auxiliary spillway. Concreting works were carried out in a mere 2 months. Hydroplus® proposed a unique scheme taking advantage of the dividing piers between each Fusegate. The inlet wells are anchored to the piers instead of being placed on the Fusegate® structure. Embedded pipes running into the piers down to the concrete weir slab connect the inlet wells to each Fusegate base chamber. Such a design improves significantly the hydraulic conditions of the system.