The new $100-million Metolong dam, in Lesotho, has achieved a significant project success this year, with the dam spilling for the first time since its completion in 2016.
Spilling occurs when the dam is at full capacity, and the dam’s spillway – meant to direct excess water downstream during flood periods – comes into operation. This was the first time the dam was subjected to the full range of stresses it was designed for, says multidisciplinary engineering and architecture company GIBB, which took the lead on the project.
Metolong dam project manager Beyers Havenga said the spilling stage was the last test of the integrity of the dam following the construction phase.
“Now we can say that the project was a success. It’s fulfilling its objective, which is to supply water to Maseru and its environs for domestic use, as well as for economic development.”
The 83-m-high dam is located 30 km east of Maseru. It features a 280-m-long crest, with a 75 m spillway just below it.
It is a roller-compacted concrete gravity dam, with a total concrete volume of 315 000 m3. It is designed to hold 63-million cubic metres of water.
The Metolong dam forms part of the Lesotho Lowlands Water Project, which is aimed at improving water supply for domestic consumption in the country and for local industry.
Several Years
“Despite only achieving capacity now, the dam has been yielding water for several years. The dam now delivers water to the water treatment works, which supplies Maseru and neighbouring towns like Mazenod, Morija, Roma and Teyateyaneng,” Havenga said.
The dam was built at a cost of $450-million and was financed by the World Bank and a consortium of funders from the Middle East, Europe and South Africa, along with the government of Lesotho.