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Kouga Municipality: Fining bulk water solutions underground

Home Engineering Kouga Municipality: Fining bulk water solutions underground

KOUGA Municipality recently commissioned four water purification plants at Jeffreys Bay, Humansdorp, St Francis Bay and Hankey. Like many municipalities, it is taking steps towards becoming more self-reliant. The Eastern Cape Industrial & Business News asked Executive Mayor, Hattingh Bornman for more background on the project.

Although there are seasonal fluctuations with the influx of holidaymakers, Kouga Municipality has a total daily average water usage of 21.5 megalitres a day (Ml/d).

Approximately 70% of this was supplied by surface water sourced from the Gamtoos Irrigation Board (GIB) and the Nelson Mandela Metro (NMM). The only surface water Kouga Municipality has developed and is in production at present is the Humansdorp fountains and fountains in Cape St Francis Bay, which accounts for 8% of total usage.

“About 70% of the water used in Kouga Municipality is provided by external sources (GIB and NMM) over which the municipality does not have full control and thus limits its water security. This was highlighted in 2022 when the NMM indicated that the Churchill supply would be shut down due to the supply dams being unable to supply water,” says Bornman.

As the NMM water treatment works at Churchill and Mpofu Dams supply water to Humansdorp, Jeffreys Bay, St Francis and Cape St Francis Bay, Gamtoos River Caravan Park, Crossways and other small water users along the Churchill Pipe, this would effectively cut the municipalities supply by 63%.

It was facing a very real disaster.

Sourcing alternative water supply

Kouga Municipality investigated new surface water sources, reverse osmosis (desalination) plants and further borehole/aquifer developments.

New dam sites were investigated, but Bornman says that they proved to be very expensive due to amongst other factors, the costs of the relevant approvals, land, and construction costs.” A dam on the Kabeljouws River was found not to be feasible due to land ownership, inadequate water security due to high upstream water consumption by irrigation farmers, legal claims on water and approvals by relevant authorities.

A number of locations were investigated for reverse Osmosis Plants. These were also ruled out due to the high cost of capital and development required, as well as the high electricity demand with associated costs, maintenance costs and the skills levels required. “This option is not viable at present, but will be re-investigated in future as new technical innovation and development may result in reverse osmosis development becoming more viable in future,” says Bornman.

The further development of boreholes is favoured by the Department of Water and Sanitation and the Department of Environmental Affairs and Tourism in areas where undeveloped aquifers are available.

“Historical aquifer investigations in Kouga Municipal area indicated aquifers that can be further developed in Humansdorp, Jeffreys Bay, St Francis Bay and Hankey and it was therefore decided to follow this route,” says Bornman.

“Borehole development is normally less costly than surface water development or reverse osmosis and less complicated with regards to obtaining the required approvals. The development of borehole fields must, however, include an extensive borehole monitoring system to be developed by the users.”

“By developing borehole fields, a strategy of diversification is followed which will result in the municipality being less dependent on external water suppliers, more water security and less risk as water is obtained from different sources.”

New process

Although the treatment process is used in mining and agriculture, the municipality believes that it is the first to set up these processing plants at municipal scale. The process is fairly new and these plants are the largest in Africa to make use of this process for municipal supply.

From the boreholes, water is oxidised in the pipelines as it is pumped to the water treatment works. At the treatment works, the water is filtrated in filters with glass media on top to remove most of the oxidised iron and manganese. Synthol media below acts as a filter to remove the remaining iron and manganese as well as the metallic taste and smell. After filtration, water is pumped into the reservoirs to mix with chlorinated water from existing sources.

The use of ‘waste’ iron and manganese is being investigated as a flocculant in wastewater treatment processes.

Cost savings

“Substantial cost savings will be achieved as borehole water production is less costly compared to buying water from the NMM for example, even including the cost of managing an extensive borehole monitoring system,” says Bornman. The operation and maintenance costs and requirements of this plant are substantially less compared to conventional treatment processes as no chemicals are required for operations.

The municipality says it cannot, at this stage, be totally independent from external supply.

Kouga Municipality’s long-term aim is to supply 70% of its average water demand via boreholes. As seasonal demand increases, the municipality says that in addition to the 30%, peak holiday supply will always have to be obtained from external sources.
The municipality procured package plants which include highly technical elements and procedures. A service provider will probably operate and maintain the plant for a specified period. In the meantime, internal staff are being trained to operate the plant and monitoring computers and screens have been installed.

Substantial backup staff for future maintenance work and possible upgrading of the plants are available in the Gqeberha area

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