Pipeline is working as planned – Umgeni

Tony Singh asks Umgeni Water to “explain to the public how they come with R38 million to have the pipeline done which ends so far from the dam” (Letters, July 3).

Umgeni Water’s response is as follows:

In 2014 KwaZulu-Natal entered a drought cycle. The effects of this are being felt at different levels throughout the province, with the worst affected areas being along the coastal regions. The Department of Water and Sanitation’s water resources infrastructure (Hazelmere Dam) is designed to impound enough water to sustain the worst drought in 50 years.

It has since emerged that the drought is worse than what the water resource infrastructure can manage and hence towards the end of last year restrictions were imposed. At that stage it was requested that consumers conserve 30% of their water demand. But this was not achieved because only certain areas had conserved water, and in some instances an increase in water demand was experienced.

With restrictions not having the desired effect and with Hazelmere Dam continually reducing, Umgeni Water considered alternate schemes for augmenting supply to the area. The most feasible solution was to construct an emergency scheme from the uThongathi River to the Hazelmere Dam catchment to transfer in the region of 8Ml/d.

It was understood, when planning this scheme, that the full transfer would not be possible during the winter months, although historical river flows from the uThongathi did show that up to half of that amount would be available to pump over the divide during winter.

The scheme was designed as a two-stage pumping scheme. The inlet to the scheme is on a Tongaat Hulett furrow alongside the uThongathi River and water is pumped from there to a booster pump station almost half way along the 7.5km pipeline. The scheme was designed to cross the Ndwedwe road and to discharge into a very steep rocky river which flows down into Hazelmere Dam. It was understood that there would be losses along this river section, although these losses were expected to be very small for this type of river and have been proved to be so.

The reason for discharging into the river and not the dam is three-fold. Firstly, the losses were expected to be small; secondly, there would be an extra cost associated with construction of this 1.5km pipeline down the steep rocky river, and finally it was expected that there would be substantial impact to the environment of trenching down this gradient.

The transfer scheme is operating as was expected. It was not expected to increase the level of Hazelmere Dam. It was implemented as a means to slow down the decline in the dam level. Before the scheme the dam was decreasing at 1% every four days. After implementation the decrease was slowed to 1% every five days during the commissioning phase and last week before the mandatory restrictions and with the transfer scheme operating at between 5Ml/d and 6 Ml/d the decline in the level of the dam slowed to 1% decrease in seven days.

With a 1% decrease in dam level every seven days the amount of water in the dam will last to the beginning of October. The risk of failure if there are no rains is still unacceptably high and hence mandatory restrictions are now being enforced to ensure consumers use less water. The Water Services Authorities are ensuring that areas only receive a certain allocation of water every day. If consumers use more than this allocation then water to the area is restricted. In this way consumers will use less water and this will allow the dam to last further into the year. As the dam decreases further and the risk of the dam failing increases, then restrictions on areas will also increase to prevent the ultimate failure of the dam.

SHAMI HARICHUNDER

Umgeni Water

Pietermaritzburg