In a briefing at Riverlands near Malmesbury in the Western Cape, Minister of Water and Sanitation (DWS) Pemmy Majodina released the preliminary findings of the cause of the dam failures in the area.
On August 8, during the early hours of the morning extensive flooding took place in the area, resulting in flooding that caused severe property and infrastructure damage to the affected area, leading to hundreds of people being provided with humanitarian assistance.
Three dams breached.
In the report, Majodina said the three dams located on Dassenberg Farm is within the jurisdiction of the City of Cape Town. However, the flooding caused by the failure of these dams affected the downstream community of Riverlands, in the Swartland Municipal area.
“These dams had no names or their names were not known. We came to refer to them as dam one, two and three, starting from the downstream dam. All of them did not have adequate spillways and initial information suggested that dam three filled beyond the safe level, resulting in overtopping due to high rainfall and associated run-off, causing dams two and one to fail in series,” Majodina said.
“On the same day, the City of Cape Town appointed a dam engineer to assess the extent of the failure of the dams, who then assessed a fourth dam – dam four – on the upper stream. At this point it was discovered that dam four also had insufficient spillway to accommodate the incoming flood. The City of Cape Town, through the dam engineer, requested permission to construct a spillway, which the department granted. The spillway was then constructed by the City of Cape Town on Saturday, August 10, 2024.”
Majodina said she instituted an investigation into the cause of the dam failures on August 11.
The investigation was also to determine ownership of the dams, verify if the dams complied with dam safety regulatory requirements and if there was proper authorisation from the Department of Water and Sanitation. The teams were given seven days to investigate.
“On August 12, our dam safety team began with the investigation in Riverlands. On arrival, our team discovered that dam four, which is the highest dam in the valley, was on the verge of failure. To reduce the risk of potential failure, our Dam Safety Office took the decision to partially empty the dam to protect the lives of the community members living downstream. Furthermore, the team discovered another dam downstream of dam one, which we call dam zero.
“Our team spent the first few days trying to prevent further damage, thus delaying the investigation. Additional resources were mobilised from our team working on the Clanwilliam Dam project to alleviate what could have been disastrous. The investigating team requested a seven-day extension to complete its work, which I granted. On Monday, August 26, they handed a preliminary report to me,” Majodina said.
The report found dam three was constructed between 1960 and 1966. Between 1966 and 1992, dam one and two were constructed. Dam four, which is the largest on the property, was built between 2000 and 2005. It appears that dam zero was constructed at the same time as dam four.
It was found the property was previously privately owned, however, it was acquired by national government in 2019 and the Department of Agriculture, Land Reform Rural and Development became the custodian of the property.
“With the reconfiguration of departments, the property currently belongs to the Department of Land Reform and Rural Development. The Dassenberg Farm is currently leased by the Department of Rural Development and Land Reform to Mazibuyinkomo Primary Agricultural Co-Operative,” Majodina said.
She said in terms of the National Water Act (NWA), the responsibility for the safety of dams rests with the dam owner which is currently the Department of Land Reform and Rural Development, which is the custodian of the property on behalf of government.
“The owner of the dams had a legal obligation to register the dams that meet the requirements to be classified as dams with a safety risk within 120 days as required by Section 120(2) of NWA. This obligation extends to all other previous owners for failure to register the dams as required. The Department of Land Reform and Rural Development failed to conduct due diligence to ascertain whether the five dams in the property are compliant with the National Water Act and whether the dams are registered with the relevant authority,” Majodina said.
She also made it clear that the dams were not constructed by government, however, it was the owner’s responsibility to follow due diligence and ensure the dams comply with all the relevant legislation.
The dams were not registered with the Dam Safety Office as per the NWA requirement by the owner.
The report further revealed that dam three failed as a result of piping failure (internal erosion) which compromised the stability of the dam wall significantly. This resulted in a domino effect on dams two, one and zero due to overtopping failures, as dam three’s capacity was larger than the capacities of the dams downstream.
“All the dams had no prominent spillway structures and therefore they did not meet the dam safety standards and standard engineering criteria. The failure of the dams could have been avoided if the dams had been registered with DWS so that they could be properly regulated, and if mandatory dam safety evaluations had been conducted by an experienced dam engineer,” Majodina said.
It was also revealed in terms of the Water Act, a license should be issued to construct a dam. There is no record of a licence being issued for the construction of any dams on the property.
“The investigation has established that dams one to four meet the requirements to be classified as dams with a safety risk since they have vertical wall heights of more than 5.0 metres and can contain more than 50,000 m3 of water as defined in Section 117 of the NWA. Dam zero is too small and therefore does not fall in this category. None of the owners (both the previous and the current owners) complied with s120 of the NWA to register the dams with a safety risk,” the minister said.
The design or construction of the Dassenberg Farm dams are not in accordance with the latest and best practices in dam engineering. According to the report, this could be because of the age of the dams and no inspections having been conducted to ascertain if the dams meet the relevant dam engineering standards. The dams were not equipped with sufficient spillways to accommodate foreseeable floods.
“The department will take action against the owner of the dams for non-compliance with the Act and associated regulations. The action will include relief for financial compensation for damage to infrastructure. Criminal investigations are ongoing and will focus on current and past owners that constructed and operated the dam in non-compliance with water use authorisation and dam safety requirements. Action may also be considered to obtain financial compensation for damage to infrastructure,” Majodina said.
She further stated the current land owners must present a rehabilitation plan for the areas affected by the failure of the Dassenberg Farm dams and implement it in accordance with applicable legislation.
The Department of Land Reform and Rural Development will be required to engage the Swartland Local Municipality in an effort to make a determination on the extent of damages caused by the failure of the dams.
Should they decided to rebuild the dams, it must apply to DWS for a water-use license and dam safety license.