Site preparation for Monwabisi desalination plant kicks off

14 Dec 2017

The site preparation for the Monwabisi desalination plant, one of the City of Cape Town’s seven desalination projects, is under way. These projects aim to make additional water available to supplement Cape Town’s existing water supply.

The Monwabisi desalination plant is part of the City’s dedicated efforts to help see Cape Town through the worst drought ever.

Seven projects have been earmarked as part of the first phase of the City’s Additional Water Supply Programme. These are the Monwabisi, Strandfontein, V&A Waterfront, and the Cape Town Harbour desalination plants; the Atlantis and Cape Flats Aquifer projects; and the Zandvliet water recycling project which will collectively produce an additional 196 million litres per day between February and July 2018.

In addition, the City has 12 projects at an advanced planning stage.

‘Being mindful of the potential financial impact on water users, the City has worked really hard to see what existing budget it has available by making tough choices and reprioritising spending to boost drought mitigation initiatives. In the first phase, seven projects are being developed using savings and reprioritisation of funds.

‘It is anticipated that the Monwabisi plant will produce a total of 7 million litres of drinking water per day which will be fed into the water reticulation system to supplement current supply from the dams and other water sources.

‘A nine-week construction period is planned for the completion of the first phase comprising two million litres. The first drinking water generated by the desalination plant is expected to be fed into the reticulation system by March 2018 with the second phase of 5 million litres to follow on after a further nine weeks.

‘The plant is intended to operate for a period of two years, based on a service agreement in which the City has agreed to buy water from the service provider, Water Solutions Proxa JV. The value of the tenders for the establishment and operation of the desalination plant at Monwabisi for a period of 24 months is R260 million,’ said the City’s Mayoral Committee Member for Informal Settlements, Water and Waste Services; and Energy, Councillor Xanthea Limberg.

All plants will comply with national legislation, which also provides for some fast-track measures for disaster relief projects such as the City’s emergency projects. Even so, to ensure appropriate controls and governance, the City has established an Emergency Water Augmentation Environmental Monitoring Committee with representatives from all relevant government spheres and departments to oversee the monitoring of the additional supply projects. The committee will also oversee the closure and removal phase at the end of the contracts.

‘There will be minimal risks to public health and safety, and work will comply with the applicable national health and safety regulations. All construction areas will be clearly demarcated and will be off-limits to the public. Any pipe work that is not underground will be clearly marked. The plant has been designed to ensure fast-tracked construction and production but with the smallest possible construction footprint.

‘The City will monitor the site and regularly test the drinking water that is produced. We are proud that the plant in Monwabisi will be our flagship desalination plant. We are truly grateful for the support of the community leadership and residents in this area. They will be true partners in this exciting and necessary development,’ said the City’s Mayoral Committee Member for Area East, Councillor Anda Ntsodo.

In addition, the Strandfontein plant site preparation is set to commence which will also produce 7 million litres of water per day when in full production.

The evaluation of a tender for a temporary desalination plant on East Pier Road in the V&A Waterfront is in its final stages. This plant is to be located in an open-air parking lot opposite the heliports, and will produce 2 million litres of water per day.

What is desalination?

Desalination is a process that produces fresh drinking water by removing salt and impurities from salt water. The Monwabisi plant is a Salt Water Reverse Osmosis (SWRO) plant.

How does an SWRO plant work?

  • Sea water is abstracted off-shore and conveyed to the SWRO plant via a pipeline
  • The plant produces high-quality drinking water from the sea water and injects it straight into the City’s water reticulation network
  • The waste product from this desalinisation process is called brine and is simply highly concentrated salt water. This is conveyed back to the sea via a pipeline, and released into the ocean through a diffuser which is designed to ensure that any potential environmental impact is limited

‘We all need to stand together, as we have done successfully already by almost halving our water usage, to avoid Day Zero. We will only beat this drought if we continue to reduce our water usage while at the same time doing everything we possibly can to make additional water available,’ said Councillor Limberg.