Water production (augmentation) plans for Cape Town
(Strandfontein temporary desalination plant.)
Bulk water supply and storage is the responsibility of central government. From this bulk supply, water is then allocated and supplied to other users (e.g. agriculture) while the municipalities are responsible only for water treatment, distribution and waste management.
If you have not already done so, please read the “FAQ’s and Honest Answers” from Helen Zille in the interview published here in the Daily Maverick.
Water augmentation initiatives by Cape Town City.
The City is proceeding with interventions to produce additional fresh water (read the excellent explanatory article about these technologies by Dr Anthony Turton here).
This chart published by CoCT in February 2018. gives an outline of the specific interventions planned. It appears that CoCT is now proceeding as fast as possible with “Immediate” and “Tranche-1” items. Starting in February, 2018, these aim to progressively produce up to 120+ML/day by July 2018.
Augmentation projects: Updated
The mayor reports that, while protecting funds for basic and emergency services, some non-water-related projects have been temporarily postponed and that R2 billion of funds have been re-prioritised to fund CoCT’s first seven additional water projects.
Here are the already announced initiatives implemented by the City of Cape Town together with their estimated water production impact and the dates by which the improvement should occur:
- Atlantis Aquifer abstraction improvements started contributing 5 ML/d extra from November 2017. Additional boreholes will be drilled to to progressively add another 20ML/day to the system by June 2018. The extra water will be used to supply neighbouring areas like Melkbos and further afield to make others independent of the “grid”. On 9th January 2018 this estimated yield was increased to 30 ML/day, with interim goal of 20 ML/d fro October 2018.
- Cape Flats Aquifer abstraction boreholes are expected to progressively contribute 25ML/d starting February and reaching full production by June 2018. Initially priority will be on abstraction but later on systems will be installed to accelerate recharge of the aquifer (as is done at Atlantis). Procurement of the boreholes is in progress. On 9th January 2018 this estimated maximum yield was increased to 80 ML/day from end-June.
- Exploratory work has commenced on the Cape Peninsula Aquifer and the Hottentots-Holland Aquifer, together expected to produce 50 ML/d after June 2018.
Given the better than expected estimated production of underground water, more resources will be diverted to this source as it is quicker and less expensive to install and operate than desalination.
- Orangezicht Springs is supplying 2 ML/d to the Molteno reservoir from November 2017. This with other mountain springs should contribute total 4 ML/d into the system from March.
- V&A de-salination plant construction has been delayed but it is intended to contribute 2 ML/d from end-March 2018.
- Monwabisis and Strandfontein desalination plants have been contracted to each produce 2 ML/d from April 2018. The first 2 ML/d of desalination output should commence in March 2018 from the new Strandfontein plant with Monwabisi following two weeks later.
- Tenders for the planned Cape Town Harbour desalination plant have closed and the proposals will be studied to decide what best should be done to bring this water production on line. It is intended to be dimensioned to produce 50ML/day but work has not yet commenced.
- Refitting the Zandvliet water treatment plant to reclaim waste water is under way – the necessary equipment is being procured which should produce 10ML/d of potable water by June 2018. Work on the Fisantekraal treatment plant, also expected to produce 10ML/day of reclaimed water per day, has not yet commenced.
- In the Steenbras catchment area CoCT has drilled several 200m deep boreholes into the TMG aquifers alongside the lower dam aiming to produce approximately 10 million litres of extra water per day at this site, after February 2018. They have struck water and pump testing is now being conducted to check water quality and sustainable abstraction volumes. It is expected that the iron and manganese content may require pre-treatment. This will be done extremely carefully as artificial recharging of such deep aquifers is not practical.
- Currently some 8% of the water used in Cape Town (i.e 47 ML/d out of total 600ML/d used is being reclaimed. Building contractors are being urged by the City to use recycled water for all non-sensitive construction work, such as dust suppression, cleaning, etc (potable water is still required for mixing cement). Reclaimed water is the least expensive and costs less that R5.50/KL. The city is planning to increase the availability of recyclable water that can be piped to some areas and trucked to others.
- Alien vegetation is being cleared in the catchments. At Wemmershoek, 50Ha of pines have already been felled and another 110 Ha will be cleared over the coming 12 months. This action is expected to save on average over 1 ML/day.
Regarding costs of such interventions, CoCT has announced that the first desalination plant at Monwabisi should produce 2 ML/day of water from March and 7 ML/day from May. Simply calculated, the total production would be 4.74 M.cuM over the two years (equivalent to just 3.3 days of water supply for the city running at current consumption rates of 10.1 M.cuM/wk).
The contracted cost of this plant is reported to be R260 million over two years, so the cost would work out at around R55 per kilolitre. By comparison, water sourced from the dams is estimated to cost about R5.20/kilolitre to produce. And the City produces and offers recycled water at under R6.00/kilolitre.
In Summary:
Actions by Cape Town City to “produce” extra water from underground water and recycled effluent are already adding over 30ML/day to Cape Town’s available water resources. Up to 130ML/day should become available from other boreholes and recycling plants by mid-2018, with all contributions from desalination planned to rise to over 160ML/d by December. If these plans come to fruition it appears that over 40% of the City’s current daily fresh water needs could ultimately be met from such augmented sources. Some shift in resources and funding from desalination initiatives to abstracting underground water has occurred.
In anticipation of “Day Zero”
City of Cape Town’s disaster management plan foresees at stage 2 of three stages (the first stage that we are now in involves extremely reduced pressure (throttling) and in some cases water outages (rationing) that the flow of potable water to most domestic users will be stopped and residents will be required to collect drinking water from collection sites that will be located across the city.
The assessment of specialists is that there is sufficient water in the system such that provided water savings continue and we receive similar rainfall inflows as last year, the closing off of water from the taps (“Day Zero”) and rationing should be deferred until at least November 2018. An assessment will be made at end-October 2018 by Department of Water and Sanitation (DWS) as to how much water may be allocated across summer 2018/2019 to the various users of potable water supplied by the main dams as part of the Western Cape Water Supply System (WCWSS).
However; “Day Zero” is not abolished and should 2018 winter rainfall turn out to be poor and less than 2017 then there is a high probability that “Day Zero” could be implemented as early as November 2018, with rationing and water collection commencing before the end of November.
Cape Town City has built and is testing a water collection point. When Day Zero arrives, Cape Town’s residents will have to collect water from centres like this.
- There will be approximately 230 collection sites across the city, some with 600 water points.
- Distance from any resident is unlikely to exceed 1.5 km.
- Residents will be able to collect 25 litres per person per day, without need for IDs.
- Each site is expected to service up to 20 000 people per day.
- The City’s Water and Sanitation Department will try to limit the impact on sanitation services and to limit the risk of disease by separately flushing the sewers with 2nd quality, recycled water.
- SAPS and the National Defence Force will be engaged to help maintain law and order with Law Enforcement at collection points
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