LHDA awards major contract for Final Phase II bridges, ensuring critical connectivity to Polihali reservoir12 September 2023
The Lesotho Highlands Development Authority (LHDA) successfully concluded the procurement process for the final two major bridges under Phase II at the end of August. The contract, worth M511,500,000.00, was awarded to the Concor-Nthane Brothers M&K Bridges Joint Venture.
Construction activities under the contract began on August 29th, with the anticipated completion of the two bridges spanning the Mabunyaneng and Khubelu rivers slated for late October 2025.
The JV is comprised of main partners Concor Construction (Pty) Ltd (South Africa) and Nthane Brothers (Pty) Ltd (Lesotho) and sub-contractors: Post Tensioning and Structural Solutions (Pty) Ltd (South Africa) and Bridge Joints and Rehabilitation Contractors (Pty) Ltd (Lesotho).
The contract for constructing the largest among the trio of bridges, known as the Senqu Bridge, was granted in late 2022. Significant progress has been made in establishing temporary site facilities at the Senqu Bridge site, and excavation work has commenced for the substantial pier and abutment foundations needed to support the impressive 825-meter-long and 90-meter-high bridge.
Upon their completion, these three major bridges will ensure continued access to Mokhotlong town even when the reservoir is at full capacity. Additionally, they will maintain connectivity to the national road network via the A1, which serves as the primary route between the mountainous northeast district of Mokhotlong and the capital city, Maseru.
“The impounding of the Polihali reservoir will submerge existing roads and tracks, affecting communities in the valleys and tributary catchments of the Senqu, Khubelu, Mokhotlong, Moremoholo and Sehonghong rivers. The major bridges along with a network of feeder roads and the main access roads to the Project area all contribute towards minising this disruption and help to restore community access to healthcare facilities, schools, shops and markets,” said Gerard Mokone, Manager of the LHDA’s Polihali Branch.
Similar to the approach taken for the Senqu Bridge, the design of the Khubelu and Mabunyaneng bridges has been carefully tailored to accommodate the challenging conditions of high-altitude construction and the harsh, frigid winters in the Mokhotlong highlands. Ensuring the health and safety of workers during the bridge construction remains a paramount concern.
The Khubelu Bridge is set to span approximately 270m, featuring nine spans of 30m each and two abutments. In contrast, the Mabunyaneng Bridge, the smallest among the three major bridges, will measure approximately 120m in length, boasting four spans of 30m each and two abutments. Both bridges will have a width of 13.55m.
“The trio of bridges will not only form part of the safe and efficient road infrastructure network constructed under Phase II but will be a major tourist attraction contributing to long term benefits in stimulating sustainable economic growth,” Ntsoli Maiketso, Phase II Divisional Manager, stated.
Work on the design of the Mabunyaneng and Khubelu bridges started in 2018, led by Zutari, formerly Aurecon Lesotho. Zutari also designed the Senqu Bridge and is supervising the construction of the three bridges.
Phase II of the the Lesotho Highlands Water Project entails the construction of the Polihali Dam, the 38km Polihali Transfer Tunnel, the associated infrastructure and a hydropower scheme at Oxbow. It builds on the successful completion of Phase I in 2003.
The LHWP delivers water to the Gauteng region of South Africa and utilises the water delivery system to generate hydroelectricity for Lesotho. Phase II will increase the current supply rate of 780 million cubic metres per annum incrementally to more than 1 270 million cubic metres per annum. At the same time, it will increase the quantity of electricity generated in Lesotho and is a further step in the process of securing an independent electricity source to meet Lesotho’s domestic requirements and reducing the country’s dependence on imported energy.
Above: NW Abutment 1 looking across the Senqu River towards the SW abutment. Access roads to and excavations for some of the 15 piers can be seen.
Top image: Cofferdam and start of excavations for the approximately 90m high pier 9 whose foundations sit partially within the Senqu River bed.