The Berg water project was undertaken to augment the water supply of the Western Cape region of South Africa, and specifically that of the Greater Cape Town metropolitan area. The project was implemented by the Trans Caledon Tunnel Authority on behalf of the Department of Water Affairs.
Aurecon provided extensive management, technical and environmental input to this significant project as a member of the Berg River Consultants joint venture.
The project consists of the following principal components:
Advance infrastructure in the form of a permanent access road and housing.
The Berg River Dam, a 62m high concrete faced rockfill dam with an embankment with a volume of 4 million m3 and a gross storage capacity of 130 million m3. This includes an outlet works and a side channel spillway.
The Berg Supplement Scheme comprising two pump stations with capacities of up to 6 m3/s and total installed power of 25 MW, an abstraction works comprising a weir, sediment exclusion works, balancing dam and revetments as well as 12km of 1 500mm diameter steel pipelines.
Particular innovations in the dam design include dynamic compaction of alluvial deposits in portions of the dam foundations and the use of articulated slabs with special water-stop features to cater for potential differential settlement.
One of the exceptional features of the outlet works is their ability to mimic the periodic natural floods that are necessary to mitigate the impact on the ecology and geomorphology in and around the river.
The plunge pool is used as an energy dissipator for the flood releases from the outlet works. Model studies were undertaken of both the spillway and the outlet works, resulting in significant refinement of the designs, including the provision of an aeration gallery in the spillway.
The Berg Water project featured planning and implementation which introduced significant achievements, such as the preservation of the associated ecological reserve, empowerment of local communities by sourcing skills and services locally and the forging of public partnerships.
The Berg Water Project has received four major awards to date.