Not only do we have a Plan A and Plan B to maintain sufficient water supply, we also have a Plan C and Plan D to ensure adequate water supply to residents in the decades to come,” says Stephen Müller, Director of Infrastructure and Planning at the Overstrand Municipality.
This follows concerns by residents that not enough is being done to prevent a
similar situation to that of other areas in the Western Cape that are currently suffering from a severe shortage of water.
According to Stephen their arsenal of plans includes the sinking of more boreholes, the purification of greywater and desalinisation.
Understandably residents are concerned over our water situation against the backdrop of the terrible drought in other areas of the country. But in the Overstrand we are in a fortunate position that we have access to enough water to meet the demand.
“People must also realise that no new dams can or will be built due to the huge ecological impact it has on the environment and therefore we need to look at other sources of water to keep up with demand in future.”
But, says Stephen, much more can be done to optimise the current water usage in the Overstrand. “It’s interesting to note that even now between 50% and 60% of municipal water is being used for gardening purposes. If residents make a concerted effort to plant water-wise gardens, we can save millions of litres every month.
“In addition, international research has shown that the average daily water usage per capita in South Africa is 235 litres compared to an average of 173 litres per capita in the rest of world. Currently people in Cape Town use less than 87 litres per person per day.”
At the moment Hermanus uses approximately 10 million litres of water per week and the level of the De Bos dam stood on 50.7% by the end of January 2018 and on 46% by end of February 2018, compared to 74.8% by the end of February 2017.
Hermanus had 54.4 mm of rain during February 2018, compared to the long-term average of 32.4 mm for February.
Saving water remains best option
The Buffels River Dam, which supplies water to Rooi-Els, Pringle Bay, and Betty’s Bay, is still at 85% of capacity, the Kraaibosch Dam at Gansbaai is also at 85%, and the Pearly Beach Dam is at 100%. The boreholes supplying Hermanus, Stanford, Baardskeerdersbos and Buffeljagsbaai have not been adversely affected by the drought at this stage.
The average daily water demand of Hermanus during February 2018 was 10.22 million litres per day, compared to 12.24 million litres per day during February 2017. This amounts to a saving of 16.5%, or 56.6 million litres of water in total in February compared to the previous year.
According to Stephen the first steps to increase water reserves will be the sinking of an additional four boreholes over the next two years. “The underground reserves we can tap into are enormous. This water system forms part of the Table Mountain Group (TMG) and is called a fractured rock aquifer, which means it is water trapped in the cracks in the sandstone. The TMG has been identified as one of the major regional aquifers in South Africa, spanning an area of 248 000 km² covering almost the whole Western Cape and part of the Eastern Cape.
“Even after three dry seasons we have not seen a drop in the level of our groundwater and it is estimated that a change in the level will only occur after at least ten dry seasons. I can assure everyone that we constantly monitor the water levels and we must adhere to very strict licencing conditions.” The nine boreholes produce op to 3.5 million litres per day.
Says Stephen: “In addition to the boreholes, reused water is the cheapest and easiest way for us to add to our water reserves. At present we use approximately 1.5 million litres of greywater for the irrigation of various sports fields and the golf course. In future we plan to build an additional purification plant to purify greywater to add to our drinking water. In fact, once greywater has been purified it is some of the cleanest water you can get.” He emphasised that the greywater does not include recycled sewerage water.
Longer term plans are being put into motion to build a desalinisation plant in Hermanus. “Although this is a very expensive option, we are in the best position possible to implement desalinisation quickly and easily. More than a quarter of your capital investment in such a plant is building extraction points to bring the seawater onto dry land. We are in the fortunate position that several abalone farms already have that infrastructure in place. We would be able to source extracted seawater from these farms. In fact, discussions in his regard have been had with the farms.
“Further to this, the fact that the seawater used by the abalone farms is already cleaner after the necessary nutrients to feed the abalone have been removed, also counts in our favour. Also, after the water has been used by the farms its temperature is higher, which assists in the desalinisation process,” says Stephen.
According to him desalinisation is highly complex, but the Municipality is gaining valuable information from the reverse osmosis process it currently applies to brackish water that is purified from two fountains near De Kelders. “Although the salt content in brackish water is much lower than seawater, the purification process is the same. We are gaining useful insight from this that will help us when a desalinisation plant is built.”
The Gansbaai region is served primarily by the Kraaibosch Dam and it has more than sufficient capacity to meet the growing demand for water. “The Municipality is an equal shareholder in the dam together with three farmers in the area. Only one of the three farms is operational and between the Municipality and the farm, less than the allotted quota is being used. Should the need arise the Municipality would be able to buy a bigger stake in the dam,” he says. This is in addition to the brackish spring water that is purified.
Both Kleinmond and Pringle Bay have never suffered from water shortages. The dams and rivers that supply water to these towns form part of the Palmiet river system that is fed by several springs and groundwater in the Kogelberg Biosphere. There are two unused boreholes in Kleinmond that can be used in an emergency.
Betty’s Bay did have minimal water problems but that was fixed by repairing leakages in the system. Should the need ever arise, the wall of the Buffels River Dam, which supplies water to Rooi-Els, Pringle Bay, and Betty’s Bay can be raised by 1.5 metres.
The spring that supplies water to Stanford provides enough water to feed both the water system and the furrows in town. “Residents have asked that we discontinue the flow of water through the furrows because of the drought. It is not necessary to do that as runoff into the furrows is water that we have no need for. The system forms part of the unique heritage of the town and we want to keep that. The water from the furrows in turn feed into the Klein River and is therefore not wasted.”
According to Stephen there are also four boreholes outside Stanford of which only 25% of the water from one is being used at the moment.
“Interestingly, the whole area surrounding Stanford used to be a large delta from which the Klein River fed into the ocean. Geological surveys have shown that there are numerous ancient, or paleo channels filled with water still running underground and feeding into the ocean. These channels are in actual fact strong running underground rivers from millions of years ago.”