The Swartland Municipality said it was forced to evacuate Riverlands residents for a second time after a spillway created to slowly release water from the fourth dam instantly turned into a flash flood on Saturday, 17 August, reports Cape {town} Etc.
This comes less than two weeks after three retention dams on Dassenberg Farm burst their banks, resulting in severe flooding which caused serious damage to homes, decimated water infrastructure and halted the electricity supply in parts of Riverlands, Chatsworth and Dassenberg, outside Malmesbury.
Also read: Riverlands dam wall breaks in Cape Town, flooding Dassenberg
‘The evacuation was necessitated following work that the Department of Water and Sanitation (DWS) was doing at the fourth dam,’ said the Swartland Municipality in a statement.
‘Although the initial plan indicated to the municipality was to slowly release water from this dam to minimise the risk of possible flooding, the plan by the department failed.’
The municipality added that it was disappointed with the department, saying it had requested on several occasions not to further intervene with the dam as the situation had stabilised and the risks were mitigated satisfactorily.
‘The municipality’s proposal was to leave the fourth dam and do any necessary work in the summer when drier conditions will have worked in our favour,’ said the Swartland Municipality. ‘The Department specialists on site, however, decided to further lower the dam levels via a newly dug spillway.’
As a result, the released water flowed quicker than expected, causing a sudden surge downstream which led to widespread flooding in the surrounding areas.
‘Die water kom, die water kom’
‘People were screaming “die water kom, die water kom” and roads quickly turned into rivers as everyone rushed to get to safety,’ said Gift of the Giver spokesperson Ali Sablay.
The humanitarian organisation was in the area providing aid to families affected by the previous flood at the time of the incident as mop-up operations for the previous flood were still underway.
In an update shared on Sunday, 18 August, the municipality confirmed that the water subsided and no injuries or deaths were reported during the incident but several residents were treated for shock at the Riverlands clinic.
While the municipality currently cares for 128 residents spread across two community centres, the update reported that residents affected by this latest incident were able to return to their homes late Saturday afternoon and no additional damage to infrastructure was reported.
However, repairs to the water network made by the municipality after the initial flood were washed away and will have to be restarted. A fleet of water tankers will continue operating in the area to provide water to residents.
‘Protect[ing] the lives of the community members’
In its statement, DWS confirmed that the fourth dam had been emptied and no longer posed a threat, arguing that the decision was made to prevent a more catastrophic collapse of the dam wall.
‘The department established that there is a progressing piping failure (on the downstream slope) at the highest section of the dam wall during an inspection on 12 August,’ said DWS.
‘The integrity of the Dam was compromised and hence the possibility of failure was detected. Subsequently, the decision was taken to empty the dam to protect the lives of the community members living downstream.’
The department also emphasised that the dam wall has not failed and that very little additional damage was caused by the release of water from the fourth damn.
‘The emptying of the dam was planned during daytime to ensure that the increased outflow from the dam would occur during daylight, to enable it to be managed more easily. Should the dam have failed late in the evening or early morning hours while the public was asleep, the consequences could have been far worse,’ said DWS.
‘Dam 4 emptied faster than anticipated, however, the public was precautionarily evacuated and hence no injuries and loss of life were reported,’ the department added.
‘The damage to infrastructure was caused by the floods of the dam breaks of the previous three dams during the early hours of [7 August].’
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Picture: Gift of the Givers / Facebook