A preliminary report into the Riverlands dam failure has revealed that all dams located in Riverlands farm in the Swartland Local Municipality did not meet the dam safety standards and standard engineering criteria.
Water and Sanitation Minister Pemmy Majodina released the report during a media briefing at Riverlands Primary School in Riverlands, in the Western Cape on Thursday.
A two-week investigation by Department of Water and Sanitation (DWS) engineers, which was granted by Majodina, followed the failure of three farm dams that breached, resulting in flooding which caused severe property and infrastructure damage to the affected area, leading to hundreds of people being provided with humanitarian assistance.
The investigation looked into what caused the failure of the three dams, determined ownership of the dams, verified if the dams complied with dam safety regulatory requirements, and if there was proper authorisation from the department.
Releasing the findings, Majodina noted that the dams had no names, hence they were referred to “dam one, two and three, starting from the downstream dam”.
“None of them had adequate spillways and initial information suggested that dam three filled beyond the safe level, resulting in over-topping due to high rainfall and associated run off, causing dams two and one to fail in series.
“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 [and] at this point it was discovered that dam four also had insufficient spillway to accommodate the incoming flood,” Majodina said.
When the DWS dam safety teams assumed the investigation on 12 August 2024, it was 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, the dam safety office took a decision to partially empty the dam to protect the lives of the community members living downstream.
Majodina said the team also discovered another dam downstream of dam one, which “we call dam zero”.
Ownership
The investigation discovered that dam three is the oldest dam, which was constructed between 1960 and 1966, with dam one and two constructed between 1966 and 1992, while dam four and dam zero were built between 2000 and 2005.
According to the report, when dams three to one were constructed, the property was owned by Dassenberg Plaas Pty Ltd, and was then sold to Agrico Machinery Pty (Ltd), which proceeded to construct dam four and zero.
The report showed that the property was acquired by national government in 2019, and the Department of Agriculture, Land Reform Rural and Development (DALRRD) became the custodian of the property on behalf of government.
“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 DALRRD to Mazibuyinkomo Primary Agricultural Co-Operative,” Majodina said.
The Minister explained that 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, as the custodian of the property on behalf of government.
Majodina said 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.
Due diligence
Majodina said DALRRD failed to conduct due diligence to ascertain whether the five dams on the property are compliant with the National Water Act and whether the dams are registered with the relevant authority.
While noting that the dams were not constructed by government, and that the property was acquired together with the dams, Majodina said the current owner was required to do due diligence and ensure that the dams comply with all the relevant legislation.
Majodina emphasised that the previous owners who constructed the dams were required to obtain a dam safety licence to construct a dam before commencing with construction. However, there is no record of any permit or licence being issued by the DWS.
The report showed that the dams were not registered with the dam safety office, as per the NWA requirement by the owner.
Dam safety standards
“Our investigation shows that dam three failed as a result of piping failure (internal erosion) which compromised the stability of the dam wall significantly. The failure of dam three led to a cascading failure effect on dam two, dam one, and dam zero due to over-topping failures since 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.
The Minister also noted that when the first three dams were constructed, the Water Act (Act 54 of 1956) which requires for a licence to construct a dam, was in place.
“There is no record of a licence having been issued for the construction of any of the dams on the property. The owners of the Dassenberg Farm appear to have constructed these dams without first obtaining a licence/permit in terms of the then Water Act.
“When the farm was sold to the Agrico Machinery Pty (Ltd), the new owner proceeded to construct the fourth dam, also without a licence to construct as required by the National Water Act of 1998.
“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 5.0m 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 [and] 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,” Majodina said.
The investigation has further established that the design or construction of the Dassenberg Farm dams are not in accordance with the latest and best practices in dam engineering.
Majodina said this could be due to the dams age and no inspections conducted to ascertain if the dams meet the relevant dam engineering standards.
Flood handling capacity
“The dams were not equipped with sufficient spillways to accommodate foreseeable floods. Had this been identified earlier, DWS would have issued an instruction to the owner to ensure that these dams have adequate flood handling capacity.
“Due to the historic existence of the dams on the Dassenberg Farm, which precedes the National Water Act of 1998, no licence in terms of the NWA was issued, and there is no record a license being issued in terms of the 1956 Water Act,” Majodina said.
Action against dams owner
Majodina said 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.”
She said action may also be considered to obtain financial compensation for damage to infrastructure, and DALRRD must present a rehabilitation plan for the areas affected by the Dassenberg Farm dams’ failure and implement it in accordance with applicable legislation.
DALRRD is also 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 Dassenberg Farm dams.
“Should the Department of Land Reform and Rural Development decide to rebuild the dams, it must apply to DWS for a water-use license and a dam safety license.
“The department is [also] required to conduct an audit of all the properties where dams have been constructed and apply for classification and registration of all dams that meet the definition in terms of Section 117(c) of NWA, to avoid a recurrence of the disaster that has befallen the community of Riverlands and Chatsworth in the Swartland Local Municipality.
“The Swartland Local Municipality should conduct a storm-water management assessment to investigate the current and future impact that the Swart River will have on the residents of the town of Riverlands, in the absence of any flood retention which was provided by the Farm Dassenberg dams,” Majodina said. – SAnews.gov.za
