State of the art dam commissioned

The Department of Water and Sanitation (DWS) are exploring all avenues to get water out to residents on the north coast of Durban and surrounding areas. Water and Sanitation Minister, Pemmy Majodina, has emphasised the important role the eThekwini Metro, iLembe and KwaDakuza Municipalities in the North Coast have to play to ensure the reticulation of water to houses.

This follows the commissioning of the world’s highest piano key weir dam, Hazelmere Dam, to improve water supply in the three municipalities.

Minister Majodina recently commissioned the world’s highest piano key weir dam (a low dam built across a river to raise the level of water upstream or regulate its flow) located in the Mdloti River, KwaZulu-Natal (KZN).

A piano key weir is a non-linear, labyrinth-type weir well suited for rehabilitation projects. This is due to a relatively small footprint and the ability to pass large discharge for lesser upstream-head values when compared with other weir types, said Minister Majodina.

The commissioning of the state-of-the-art dam comes after the DWS successfully completed a project to raise the dam wall by seven metres to increase storage capacity, and to augment water supply to areas including Verulam, Groutville, Blythedale and Ballito. Speaking during a community engagement, Minister Majodina emphasised the important role that municipalities have to play to ensure the reticulation of water.

“The Department of Water and Sanitation upgraded the Hazelmere Dam wall to meet the needs of the increasing population in the North Coast, as it is our role to ensure bulk water supply. The concerned municipalities should now roll up their sleeves to ensure that water is directed to households,” Ms Majodina said.

The North Coast of KZN has experienced rapid growth in recent years, especially in the housing sector, which resulted in an increased demand for potable water, she said.

“Hazelmere Dam can now be measured against world class standards due to the type of spillway selection, technology and innovation used in implementing the project.The raising of the dam wall will address water challenges in some parts of the three municipalities,” she said.

The project scope of the work includes the raising of the dam wall by seven metres (from 86m to 93m); the construction of and retrofitting a piano key weir (PKW) onto an existing dam spillway structure; the installation of 83 rock anchors, as well as foundation grouting and other minor related works.

The Minister added that the dam has an uncontrolled PKW spillway. This was done to ensure that the dam wall withstands extreme concentration of floods of between six and eight hours for the dam catchment area.

“Some of the employed technologies undertaken to upgrade the dam wall include the world’s highest piano key weir; the world’s largest anchors were installed to improve stability of the concrete gravity dam wall structure, and the largest capacity post-tensioning stressing jacks were deployed during construction,” the minister said. “The technologies employed also included the use of innovative data management software for real-time monitoring of anchor performance and 3D digital crack meters. The upgrading of the wall assisted with the creation of employment opportunities for 187 locals, including 16 women and 53 young people.”

Minister Majodina said a total number of small, micro and medium enterprises (SMMEs) appointed were 11, with two of them being owned by women. In addition, the successful training of 14 engineers took place during the project, with some subsequently obtaining professional registration, marking a significant achievement in capacity building, she said.