The City of Cape Town Council approved the R2.3-billion Water Supply Agreement (WSA) with the Department of Water and Sanitation (DWS) on October 27, 2022 for the Berg River to Voëlvlei Augmentation Scheme (BRVAS).
The BRVAS, implemented by the DWS and the Trans-Caledon Tunnel Authority, enables the abstraction of surplus winter water from a proposed low level diversion weir across the Berg River and the pumped delivery of that water into Voëlvlei dam.
The Western Cape Reconciliation Strategy Study, developed by the DWS, identified the need to augment the Western Cape water supply system. A detailed feasibility study found that the BRVAS would be the most cost-effective solution, producing about 63-million additional litres of water a day and increasing the yield by about 5.22% once completed.
Acting Water and Sanitation MMC Siseko Mbandezi says the City of Cape Town must conclude a 20-year WSA with the DWS, which was stated in the contract.
The contract, which incurs a financial obligation proposes to boost supply to the City of Cape Town by about 40-million litres of drinking water a day from mid-2025.
Mbandezi says the BRVAS is an important component of the Cape Town City Water Strategy to help ensure long-term water security to navigate future climate shocks and droughts.
“The BRVAS project involves the pumped abstraction of surplus winter water from the Berg River once the ecological water requirements of the River and the estuary have been met.”
The scheme consists of the pumped abstraction of water in winter from the Berg River to increase the yield of the Voëlvlei dam by about 23-million cubic metres a year; a low-level weir and pumpstation to be located at the Lorelei site on the Berg River; and a 6.3-km-long pipeline to deliver the water into the dam.
The pipeline will be designed for reverse operation during summer so that releases can be made from the Voëlvlei dam to the downstream users and the ecological water requirements of the estuary can be met.
Once finance from the National Treasury has been secured, a service provider or contractor will be appointed. The detailed design of the scheme must still be undertaken, states Mbandezi.
The BRVAS is a critical component of the City of Cape Town’s water strategy, which aims to increase available supply to the City by adding 300 Mℓ/d of water by 2030.
Other water augmentation schemes that are being implemented as part of the water strategy, and which will diversify supply, are groundwater development, water reuse and desalination, Mbandezi concludes.