The engineer who saved the Dam

by Willie Meyer – from his book “Magaliesberg Kaleidoscope”

The construction of Hartbeespoort Dam was one engineering project envisaged for many years but was so fraught with legal, social and engineering problems that it almost did not come to fruition.

The dam wall as it eventually looked after completion. Photograph courtesy Hartbeespoort Dam Snake and Animal Park

Just when everything seemed to fall into place, floods in 1921 and the engineering problems inherent in the project caused the engineer in charge to throw in the towel and many others involved in the project decided to call it a day. It was at this desperate stage that the government decided to appoint a young engineer, FW Scott, to take charge of the project.

In an affidavit Johan Schoeman submitted to the government concerning his claims for compensation later on, he described Scott as the only honest engineer involved in the construction of the dam. The others, he implied, were only concerned with enriching themselves and getting as much as they could for their own benefit. Scott also supported Schoeman in his efforts to uplift the “poor whites” that initially formed the bulk of the labour force employed in the construction of the dam. 

Scott immediately revised the plans and suggested to replace the enormous gravity wall (the same type of wall that was used at Sophia Dam which collapsed in 1909) with an arched wall, which would be supported against the rock faces on both sides of the Poort. Because the barrage was already placed in the far northern position in the Poort, Scott could not choose the ideal position for his arch wall. The compromise was thus a position where the western side support reached only half the height of the wall. The remaining support he got from broadening the wall on that side, and spanning the bridge that stretched over the spillway and using the weight of the “Victory Arch”.

The Hartbeespoort Environment Heritage Association, in an unattributed report on the history of the dam[1], says that after Scott’s appointment everything went smoothly. The cofferdams were reinforced in April 1921 and on 24 May the river was “tamed” so that concrete could be poured into the new foundations of the wall on 26 July. On 7 September the wall was already 2m high and in 1922 it could handle the floodwater. The wall was completed in 1923.

The road over the dam wall provided a route through the Poort for the first time. Photograph courtesy Hartbeespoort Dam Snake and Animal Park

Despite the scope of the project and the number of unskilled people working on the wall, and the haste to complete the project, only four fatal accidents were reported.  One of the workers was killed at the tunnel and the other three fell off the half-finished wall at different stages. In 1927 their relatives and friends erected a monument for them on a slope of the Magaliesberg near the tunnel. The inscription reads:

Deze steen is opgericht voor de arbeiders van Hartebeestpoort Irrigatie Werken ter ere van: Stobie, Putter, Venter en Dixion, die verongelukte zyn in het verrichting van hun arbeid.

RUST IN VREDE”

(This stone was erected for the labourers of Hartebeestpoort Irrigation Works to honour: Stobie, Putter, Venter and Dixion, who were killed during the execution of their work. REST IN PEACE.)

FWC Venter was killed in 1922 when he was thrown from the wall by a cable car just before he was to come off duty that afternoon. He fell off the dry side of the wall and was killed instantly. His friends knew him as a quiet introverted person, unmarried and about 30 years of age. Of the others nothing is known.

At the height of the construction, towards the end of 1924, 2 500 workmen and 19 engineers were directly employed to have Hartbeespoort Dam completed by the end of that year, as reported in the Irrigation Magazine of 15 June, 1924. 

One of the “modern” innovations incorporated in the wall of the Dam was a small hydro electric power plant which was commissioned shortly after the completion of the wall in 1924. It was in operation for about 40 years, supplying electricity for the operation of all the pumps and other equipment as well as the residential areas and offices of the Department of Water Affairs.

The power plant was an almost forgotten feature of the dam after it was decommissioned about 40 years ago. It, once again, came to the public’s attention when reports about it appeared in the press after a site visit in 2008[2].

Research into the history of the power plant reveals that all the valves and cast iron pipes of the plant were manufactured in England and shipped to Cape Town for delivery to the site by rail.

The drop from the East bank canal to the river was to be used to drive the turbines for the hydro-electric generator to supply electricity to the immediate surroundings.

The machinery arrived by March 1924 and on 13 June of that year it was reported that the plant had been in operation for a couple of months. It replaced the 45 KW paraffin oil generator that was removed for use elsewhere.

Apparently, the plant was damaged by lightning in December 1924 but reports that it had then been decommissioned were refuted by a resident whose father was the electrician responsible for the installation and maintenance of the plant.

Ms Joanita Norman was born in the Water Affairs compound and her father, Mr JMP Redelinghuys, was the electrician responsible for the plant from 1922 until he retired in 1949. According to Ms Norman her father kept a diary of events concerning the plant and he didn’t mention the lightning strike of 1924.

However, he did mention the floods of 1944 and how he and his assistant tried to save the equipment when it became clear that the plant would be flooded. Eventually they had to flee for their lives. She remembers how he later tried to dry the meters in her mother’s oven.

The plant was still operating when he retired in 1949 and supplied all the electricity for the immediate area.

When ESCOM (as Eskom was known then) was contracted to supply power to the Department of Water Affairs in the early sixties, Jack Seale and Sydney Swarts from the Lake Hotel, offered to rent the plant from the Department of Water Affairs because private businesses and residential areas around the Dam had to supply their own power. The department, however, for various reasons, was not prepared to rent out the plant. Eskom shortly afterwards extended its services to the whole of Hartbeespoort and the plant was forgotten.

But early in the 21st century plans were mooted to resurrect the hydro-electric power station. The Department of Water Affairs planned to re-commission the plant and use the electricity to power the equipment needed to reclaim sediment from the bottom of the lake. Huge suction pumps would be needed for this operation and their power consumption would have been such that it would be economical to have power generated locally.

That would have required the refurbishment of the whole plant, which would have amounted to virtually a new plant. With the cost of power generation and the possibility of selling excess capacity to the Eskom grid (the so-called REFIT – Renewable Energy Feed In – option), it could just have been a viable proposition.

A copy of the book by Willie Meyer is available at the Kormorant office.

Also see:

The building of the Dam Wall

The Dutchman who wouldn’t budge

Dam of dreams