Bringing water to the people of Lesotho: Lafarge proud of its role in the Metolong Dam

The spectacular mountains of the Kingdom of Lesotho are typically associated with an unceasingly bountiful supply of water – and yet the communities in Lesotho’s Lowland areas have historically suffered from water shortages. The Metolong Dam is the major structure in the Metolong Dam and Water Supply Programme (MDWSP) designed to address this disparity and provide potable water to Lesotho’s rapidly growing population, as well as remove the water constraints on the country’s key textile industry.

First commissioned in 2016, the Dam has been delivering raw water to the water treatment works built to supply around two-thirds of the country’s 2 million people, largely located in Lesotho’s capital, Maseru, and the neighbouring towns. With Lafarge South Africa’s long association with many of the world-class water projects in the Mountain Kingdom, it was a special occasion in August 2018 for all parties involved with the project, when the Metolong Dam reached full capacity and began overflowing its spillway for the first time. The last test in the commissioning of any dam, Metolong had proven its integrity!           

Lafarge South Africa is a member of the international LafargeHolcim Group, a world leader in building materials. The Group is committed to addressing the challenges presented by urbanisation and uses its technical strength to contribute innovative solutions for sustainable infrastructure.

A major RCC dam

Metolong Dam is an 83 m high roller-compacted concrete (RCC) dam with a crest length of 280 m, constructed on the Phuthiatsana River. The main contractor established an on-site batch facility to provide approximately 330 000 m³ of RCC and 40 000 m³ of conventional vibrated concrete (CVC).  The contractor was a global top-ranking construction and hydropower group, which was involved in a range of projects on the African continent, and had worked on major international projects such as China’s Three Gorges Dam, the world’s largest dam.

Lafarge’s holistic approach

Ash Resources, Lafarge South Africa’s fly ash company had been supplying its quality DuraPozz® classified siliceous fly ash for the construction of water pipelines and other water infrastructure, and was well-placed to supply the Dam project. In keeping with its ‘One Lafarge’ holistic partnership approach with main contractors on major infrastructure projects, Lafarge South Africa focused on contributing innovative technical, commercial and logistical solutions to help ensure the successful construction of the project rather than merely being a commodity building material supplier. Realising Heat of Hydration would be a significant concern for mass concrete pours, Lafarge proposed their premium technical cement, Powercrete CEM II 42,5R.

Innovation in cement

Cement for water infrastructure projects in Southern Africa had traditionally been dominated by CEM I products, whereas Lafarge’s innovative CEM II product was a Low Heat cement and also had the capability of being enhanced further on site with additional fly ash, enabling the contractor to customise cost-effective mixes as required. However, the engineers and the contractor for the Metolong Dam were not familiar with this versatile, high performance product. It took a two-year determined motivation campaign, with strong technical support from Lafarge’s highly regarded accredited civil engineering testing facility, Quality Department Southern Africa (now renamed Integrated Solutions and Innovation Centre), to achieve a change in the technical mindset and a commercial breakthrough. A significant benefit for the contractor was the same quality and source of fly ash would be incorporated in the cement as would be used for on-site concrete batching.

The outcome of extensive laboratory evaluations of the proposed RCC (Roller Compacted Concrete) and the CVC (Conventional Vibrated Concrete) mixes for the Dam was the selection of Powercrete cement from the Lafarge Lichtenburg Cement Works, and DuraPozz® fly ash from Ash Resources’ Lethabo Plant as binder materials. The Lafarge products had performed exceptionally well, exceeding the contractor’s expectations. The longer term impact was the significant technical breakthrough achieved by Lafarge in the choice of a CEM II cement for RCC dam construction in Southern Africa.

Pride in delivery service

Delivering to the remote mountain site of the Dam was a continual logistical challenge, but  

the Lafarge logistic teams have a recognised track record for ensuring product is always available on a customer’s project site, no matter what delivery challenges may be encountered. For Metolong, Lafarge complied fully with the contractor’s requirement of an eight-day estimated usage stock on site to avoid the project running short of materials.

Safety the No 1 priority

Another facet of Lafarge’s culture that impacted positively on the Dam project was the company’s non-negotiable priority concern for safety. In an impressive performance, over a two-year supply period to the challenging remote project site, there were not any Lost Time Injuries at the Lafarge Cement Works, Ash Resources’ Lethabo production plant, or among their transport contractors.

Performance praised

“The highly-experienced international main contractor was extremely complimentary about Lafarge South Africa’s service on the project saying we gave them outstanding support and, in particular, achieved a hundred per cent on-time delivery record to site,” says Andrew McKeen, Infrastructure Civil Development Manager – Lafarge South Africa. “It is rewarding to see Metolong Dam successfully complete its full capacity test, and to witness the people in the Lesotho Lowlands starting to benefit from a quality, reliable water supply.”

 Concrete work  on Lesotho’s Metolong Dam nears completion at the end of 2014.

The innovative Lafarge products provided the solution for the RCC and CVC concrete.

Metolong Dam showing the completed spillway.