Page 59 - Bulletin 23- 2020

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Clearing the sandbar at the sea

To avoid the necessity to allow the winter rains to cause flooding, prior to natural breaching

of the sand bar at the sea, several mechanical methods of “clearing the bar” were

investigated.

These investigated methods included the provision of a pair of large inflatable weirs with a

pumped system for automatically eroding the sand bar. Full scale experiments on site with
pumps running for several days showed the method to be effective.

Other bar-clearing methods that failed included:

- water jetting with fire-hoses (a dozen firemen were very wet after trying this method) and
- burial of large water pipes with multiple nozzles creating a local quicksand condition

between the rubble weir and the sea.

Anglo American offered to provide the “double inflatable weir” solution, but the CCC

preferred their “bulldozer at low tide” method, that had been used over many years.

Provision of additional water

Investigations showed that to overcome the seepage and evaporation losses during summer an
additional water supply was needed to maintain the “Operating Water Level”.

A large Fehlmann radial well, 27m deep, over 3m in diameter with lateral screens extending
40m to the sides was constructed near the shore on the alignment of the Muizenberg beach

promenade. The pumping system had the capability of more than 14 million litres per day.

This was built at considerable cost to Anglo American. It was commissioned and handed over
to the CCC, but was never used. The surface pump-house has been demolished.

Appearance of banks – a critical aesthetic Issue

At the outset of the project the planning team identified the appearance of the waterside

banks as a critically important aesthetic issue. I was asked to investigate this matter as an
issue of great importance in my 1971 visit to comparable overseas projects with Quentin

Scott.

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