The Department of Water and Sanitation (DWS) has sent a team of dam safety engineers to conduct a technical assessment of, and monitor, reported damage of a privately-owned dam near Barberton, in Mpumalanga, that had been reported to be at risk of failure.

The department is working with the owner’s previously appointed approved professional person (APP) for the dam, which is named My Own Dam, but publicly referred to as Senteeko dam.

The dam, an earthfall embarkment dam with a concrete spillway, is registered with the DWS’s Dam Safety Office as a 26-m-high medium size dam, with a storage capacity of 1.8-million cubic metres, and is owned by Shamile Communal Property Association. It is used for irrigation purposes.

“Assessments and observations by the department’s dam safety specialists indicate that undercutting of the spillway channel is continuing, eroding and posing a threat to the stability of the structure. The spillway channel slab is currently slightly suspended or cantilevered,” the DWS said in a statement late on Wednesday.

“There is currently no overtopping of the dam wall and no excessive seepage has been observed on the earthfill embankment wall.”

The dam’s outlet valve is fully opened in line with the dam operating rules; however, owing to increased inflows from the Die Kaap river, which is a tributary to the dam, the lowering of the dam water level has been minimal.

The owner of the dam is expected to start excavations of a side-channel spillway, under the supervision of the APP, to lower the water level in the dam, thereby reducing undercutting of the spillway channel and preventing catastrophic failure of the dam.

It is anticipated that this exercise will proceed even if additional rainfall is experienced.

Observations of the upper reaches of the Die Kaap river by the Inkomati-Usuthu Catchment Management Agency indicate that river flows have decreased since January 19.

The Crocodile river, located 60 km from Senteeko dam, is currently flowing within normal recent peak levels.

“Any additional flows that may result from an unforeseen dam failure, should the current intervention measures not prevent it, are expected to have minimal impact on transboundary flows to Mozambique which are currently elevated owing to the recent flooding conditions.”

The areas most likely to be affected have been identified as those in close proximity to the dam, particularly the Barberton Valley.

Relevant communications, warnings, and evacuation processes are being implemented by the relevant authorities.

The department will continue to monitor the dam closely.

“The DWS takes dam safety seriously and urges communities to comply with all evacuation orders issued along the Die Kaap river. The public is also advised to avoid low-water bridges, unnecessary travel and activities near rivers.”