The construction of the new Metolong Dam will provide a much needed boost for Lesotho’s capital, with Chinese contractor Sinohydro forging ahead with the construction programme, driven by its Cat earthmoving fleet.

CONSTRUCTION IS NOW well advanced on the Metolong Dam and Water Supply Programme (MDWSP). The dam is designed to ensure a dedicated future downstream source of potable and wastewater for domestic and industrial use for Lesotho’s capital, Maseru, as well as the neighbouring towns of Teyateyaneng, Roma, Mazenod and Morija, which will help meet Maseru’s medium- to longer-term macroeconomic objectives.

Valued in excess of R540 million, the project will be implemented in set phases. Sinohydro Corporation was awarded the contract for the construction of the key stage, namely the Metolong Dam and allied pump station, and established on-site in January 2012.

Situated on the Phuthiatsana River, some 35 km from Maseru, this will be a 73 m high roller-compacted concrete (RCC) dam. The coffer dam was completed at the end of February 2013, allied with the earlier construction of a 4.4 m x 5.5 m high deviation tunnel measuring 248 m in length and drilled through solid rock. Once fully constructed, the dam will have a designed capacity of 53 million cubic litres with a 210 m crest length and a reservoir with an upstream reach of approximately 16 km. Sinohydro’s goal is to have around 80% of the dam wall completed by the end of 2013 Construction of the raw water treatment works,being carried out by a separate contractor, is now also in progress. Concrete quantities for the dam entail approximately 280 000 m³ of RCC and 40 000 m³ of normal concrete, with Sinohydro having set up batch plant facilities on-site. Concrete aggregates are drilled, blasted and excavated from nearby sources. A global hydropower specialist and construction group based in Beijing, Sinohydro traces its origins back to 1950 and is now ranked 23rd out of 225 international contractors, according to the 2012 poll compiled by US-based magazine Engineering News-Record, and is ranked sixth in terms of Chinese construction companies. Rankings are based on annual revenues generated.

In its home country, Sinohydro continues to be a major player in the establishment of China’s modern-day infrastructure and has worked on mega projects that include the world’s largest water scheme: the Three Gorges Dam project on the Yangtze River. Back in Africa, Sinohydro is currently active on a range of hydropower and road projects across the continent, where, as in the rest of the world, its preferred earthmoving requirements are driven by Cat machines.

On the Metolong project, these include the deployment of a Cat D8R dozer for general construction and three Cat D3K dozers that are being used for the RCC phase, as well as Cat 966H wheel loaders, Cat backhoe loaders,compactors and a range of Cat hydraulic excavators ranging from Cat 320D L, 330D L to 336D L units. Local support is provided by Barloworld Equipment’s Maseru depot. Approximately 18 tipper trucks have been used during the bulk earthworks establishment programmes.

From a donor perspective, the Metolong Dam is being designed and constructed with funds provided by the Kuwait Fund for Arab Economic Development (collectively KBOS), the Saudi Fund for Development, the OPEC Fund and the Arab Bank for Economic Development in Africa. The World Bank funded the Environment and Social Impact Assessment for the dam.

The project’s overall scope of works by the various appointed contractors entails the construction of a 75 Ml/d water treatment plant and ancillary facilities, which include a raw water transmission main and a high lift pump station for the treated water. Funding for the water treatment works is being provided by the Millennium Challenge Corporation.

The water treatment works has three major components, namely a 800 m long, 1 100 mm diameter raw water transmission main (sized for 2035 demands) from the dam to the water treatment plant located on the top of the right bank; a 75 Ml/d water treatment plant (WTP) to meet 2020 demands, with a peak capacity of 94 Ml/d; and a pump station at the WTP with an average pumping capacity of 859 l/s (75 Ml/d) and a peak discharge capacity of 1 088 l/s (94 Ml/d) to meet 2020 demands. Then there is the Downstream Conveyance System (DCS), which requires construction of transmission pipelines, reservoirs and other ancillary facilities to convey treated water to Maseru, Morija, Mazenod, Roma and Teyateyaneng.

In the initial phase, the installed pipeline system will have the capacity to supply Maseru with around 75 000 m³/d, guaranteeing water on tap for its citizens, as well as for the capital’s thriving industrial base.