The Department of Water and Sanitation (DWS) has emptied the fourth dam in Riverlands, in the Western Cape, by means of a side channel spillway to prevent a more catastrophic collapse of the dam wall.
This followed the August 7 breach of three farm dams in Riverlands, which resulted in flooding that caused severe property and infrastructure damage.
An inspection of a fourth dam on August 12 found a progressing piping failure on the downstream slope at the highest section of the dam wall.
“The integrity of the fourth 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 DWS said in a statement issued on Sunday.
The draining of the fourth dam was undertaken during the daytime on Saturday to enable it to be managed more easily.
However, the dam emptied faster than anticipated and the public was precautionarily evacuated and no injuries and loss of life were reported. The members of the public who were evacuated have returned to their homes, the DWS said.
“The dam wall of dam four has not failed. Very little additional damage was caused by the release of water from dam four. The damage to infrastructure was caused by the floods of the dam breaks of the previous three dams during the early hours of August 7,” the department said.
Meanwhile, on Friday, Water and Sanitation Minister Pemmy Majodina granted departmental engineers an extra week to conduct diligent and adequate investigation into what led to the failure of three farm dams.
According to the DWS, the three failed dams did not have sufficient spillways and had filled beyond the safe level, resulting in overtopping owing to high rainfall and associated runoff, causing them to fail in series.
The fourth dam, which is the highest dam in the valley, also has no spillway, and it was discovered that it had some structural damage.
DWS noted that, depending on the results of the investigation, DWS may implement regulatory actions to ensure accountability.
A previous press statement by the DWS noted that the four dams are not owned by DWS; however, as DWS exercises a regulatory function over all the dams in the country, it has since sent engineers on the ground to assist with normalising of the area. 