Jeffares & Green Water Division working on projects worth multi-billions - Water & Sanitation , July/August 2009
Jeffares & Green (J&G), firm of consulting engineers, has just signed a R22 million contract with Mozambique to carry out rehabilitation on the Nacala Dam, the main source of water to the Nampula province. The contract was awarded after an international tendering process.
The contract provides for increasing the dam’s capacity to 21 million cubic metres benefiting around 70% of the population in the Nacala area. Currently, the dam has a capacity of 14 million cubic metres and supplies only 20% of the population.
The Nacala Dam is in a state of disrepair, and the reduction of the water level since 2005 has seen a portion of the local population relying on cisterns. J&G will be assisted on the project by Lamont (Zimbabwe) and Conseng (Mozambique). The hydrology, geotechnical engineering and environmental services will be undertaken by Terratest.
In total, a team of 34 engineers, hydrologists, as well as social and environmental specialists will be assigned to the project which will be undertaken in three phases: feasibility studies, detailed design and tendering process, and construction.
According to J&G director Andy Pepperell, the project will investigate several key aspects. “The first will be to determine the current condition of the dam to check its safety factors. The second will be to raise the dam capacity so as to increase its yield and to provide additional water for environmental purposes. And the third will be to redesign and reconstruct the dam spillway to ensure that it is fully compliant with international dam safety requirements,” said Pepperell.
Construction is expected to commence towards the end of 2010. Work on the dam is expected to cost R95 million, expanding the Nacala water supply system will cost a further R81 million and reconstruction of the waste water collection system will cost another R140 million.
Botswana, Dikgathlong Dam
An important milestone has been reached in the construction of the Dikgathlong Dam, which is a project run by the Botswana Department of Water Affairs (BDWA).
This entails the diversion of the flow of the Shashe River so that the dam wall can be built through the dry river bed during the winter season. The dam has been under construction for just under a year. A core trench excavation through a section of the Shashe River started at the beginning of May and a diversion conduit has been successfully installed. This runs parallel to the river channel and carries the dry-weather flow around the dam wall excavation.
The diversion has now been put into use by means of closing the upstream and downstream coffer dams and the contractor is in the process of excavating the core trench through the now dry river-bed section. The aim is to bring the main clay core up to riverbed level by the end of the dry season after which it will be suitably protected to allow the river to flow along its natural course again during the wet season.
At a cost of R2.4 billion provided by the Botswana government, the dam will not only be the largest source of water in Botswana but will also be used to establish and operate a new coal mine and a 3 600 MW power station at Mmamabula, approximately 130 km north of Gaborone. Since power will be fed into the Eskom grid in South Africa, Dikgathlong Dam will not only be vital to Botswana but extremely important to South Africa as well. The dam is scheduled to be up and running by October 2012.
Lesotho, Metolong project
In the Kingdom of Lesotho, the Lesotho Lowlands Bulk Water Supply Project was completed at the end of October 2008, and Jeffares & Green (J&G), who was part of an international joint venture team working on the project, was asked to put together a proposal for the preparation of a design-and-construct tender document for the Metolong wastewater treatment works (WTW). This is to be followed with technical assistance in implementing the project. The project is being funded by a number of international funding agencies, such as the World Bank, the European Union, the Millennium Challenge Corporation and a group of Arab Banks as well as the governments of Lesotho and South Africa. Construction of the Metolong WTW and bulk water conveyance system is due to start in 2010.
Water quality
Water quality has become an issue of serious concern recently and J&G is currently working on two projects with the Water Research Commission. The first is an analysis of water laboratories throughout the country to identify capacity gaps, laboratory statistics, staff issues and testing methodologies. These have been compiled into a survey of national laboratory facilities. The project will eventually result in the development of a tool, both for water services authorities and for the regulator, to enable improved water quality testing. It will also improve laboratory coverage of the country and capacity within the laboratories.
The second project involves the development of an innovative integrated water quality management model. The model addresses the current split between water resource quality management and drinking water quality management. A paper arising out of this project has been accepted for platform presentation at the National Drinking Water Quality Conference and at the first International Water Association Development Congress in Mexico City.
Another cutting-edge project is being undertaken by J&G’s Cape Town wastewater specialists. They are working to improve the quality of storm water in order to improve the quality of marine water at the point of discharge.
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