Work to raise La Gogue dam to be completed in December 2022 |30 October 2021
Ms Victor (Photo: Thomas Meriton)
The Public Utilities Corporation’s La Gogue Dam project which started in 2018 will now be fully completed by December 2022 as 97% of the work has been completed.
Originally, work to raise the level of the dam was expected to finish by the end of 2019, but the targeted completion date was later pushed to June 2021 and once again the Public Utilities Corporation (PUC) has said that additional work has to be done before the dam can be commissioned.
It was the project manager, Erna Victor, who made the statement in a briefing with the press at the La Gogue dam site yesterday morning.
Ms Victor said that as was mentioned during the last update in March this year, additional work was needed on the dam, which was 95% complete. That was in regards to stabilising the slope on the south saddle dam (looking towards Sorento, Glacis), one of the lowest areas within the La Gogue dam and also remedial works to control seepage on the far-right of the dam’s embankment (right abutment), where part of the dam’s clay core was found to be absent.
“Work on the south saddle of the dam has started and is around 40% completed but work on the right abutment, where piling is supposed to take place, has not started yet and we expect to start by January 2022,” Ms Victor said.
Work at the south saddle of the dam is aimed at improving the stability of the slope and control seepages through the dam’s structure once it reaches its maximum capacity of 1.6 million cubic metres. Currently, a carpet-like material known as PVC membrane is being laid upstream at the south saddle dam. This will eventually be covered with a layer of rocks similar to that found at the embankment. This will be further complemented by two four-metre deep drainage trenches, downstream of the south saddle dam facing Sorento. The main purpose of the trenches is to drain the saddle and lower the water table in the slope. In addition, a rockfill embankment will be constructed at the toe of the slope to provide further stability.
Piling works are expected to be undertaken on the right abutment to address seepages. This solution will consist of the construction of a 37m long secant wall with piles of one-metre diameter and an average depth of 30m. In addition, jet grouting injections will be undertaken underneath the spillway to address seepages. This component is expected to begin in January 2022 if everything goes according to plan.
The additional works on the dam is expected to cost R98 million and is being funded by the African Development Bank (AFDB). Approximately R182 million has already been paid so far for the work done on the project to raise the level of the dam by six metres.
Upon completion, the dam will be 45 metres deep with an additional 600,000 cubic metres of water in storage capacity, 60% over the current figure which stands at one million cubic metres.
The dam will be fenced off to prevent access by unauthorised people while a road will also be built all around. The original dam was built in 1976.
Patrick Joubert / PUC press release
