R30-billion water transfer plan to top-up Durban’s giant ‘leaking bucket’

Two of these giant mechanical moles/tunnel boring machines will be needed to carve out a 33km-long underground tunnel between Bulwer and Baynesfileld. The machines incorporate a cutter head with an outside diameter of about 4,5m. (Photo: Nemai Consulting report)

By Tony Carnie

31 Jan 2023

Government authorities are planning to build what would become the country’s biggest water transfer scheme to slake Durban’s burgeoning water demand — when more than 56% of the city’s water is now leaking out of broken pipes, is stolen or not paid for.

The proposed uMkhomazi water transfer scheme involves building two major dams on the third-largest river in KwaZulu-Natal, and boring a 33km tunnel beneath mountainous terrain to shift the captured water to a new purification plant northwest of Durban.

Building the first major dam (the 81m-high Smithfield Dam near the town of Bulwer) will also entail relocating sections of the Eskom high voltage network and provincial roads; the possible installation of several hydroelectric turbines along the water route to Durban, and a significant increase in water tariffs in several parts of KZN.

water transfer durban The proposed Smithfield Dam, along with major water transfer and treatment infrastructure is likely to cost at least R30 billion. (Photo: Department of Water and Sanitation)

According to the national Department of Water and Sanitation, the uMkhomazi transfer scheme will become “the largest water transfer scheme in South Africa, comparable to the Lesotho Highlands Water Project in terms of water volume and tunnel lengths and diameters”.

The first phase alone aims to purify up to more than 600 ML/day at a time when water consumption in the eThekwini (Durban) municipality has increased by nearly 200 ML/d over the past five years — largely due to leaking pipes and other infrastructure failures. That is equivalent to about one-third of the water that will be generated by the new scheme, even before it is built.

water transfer durban Durban is running out of water and faces a growing deficit unless more water is saved or stored (Graph: Department of Water and Sanitation)

At a meeting on 26 January to brief the media on Umgeni Water’s latest annual report, chief financial officer Thami Mkhwanazi observed that Durban is Umgeni’s largest single customer, accounting for nearly 75% of the water utility’s business.

A recent report to Ethekwini council’s executive committee laments the likelihood of higher water tariffs due to 56% of its water being lost to leaks, theft or non-payment. (Image: Ethekwini Council)

Last year, Our Burning Planet also revealed that the eThekwini municipality’s “non-revenue water” use has soared to 56% compared with just under 37% five years ago. Ten years ago, the city’s non-revenue water losses stood at 33%.

Where Durban’s water goes to

water durban A table explaining Durban’s current water balance. It shows that more than 56% of the water purchased by the city is not paid for and is classified as Non-Revenue Water. It also suggests that more than 44% of water purchased from Umgeni Water is lost from leakage (either from faulty pipes and meter connections or overflowing storage tanks) while the remaining 12% of losses is attributed to unauthorised or unbilled water use. (Table: Ethekwini Council)

Senior national water department official Ashley Starkey has also cautioned that eThekwini will be facing water shortages soon unless the new uMkhomazi water transfer scheme is brought into operation to supplement the existing Midmar, Albert Falls and Inanda dams.

The main uMkhomazi dams and the transfer scheme will be built by the national department (through the Trans-Caledon Tunnel Authority), with Umgeni Water responsible for the new treatment works near Baynesfield outside Pietermaritzburg, but no firm construction date had been announced.

Nevertheless, Umgeni Water confirmed in a recent media release that several KZN municipalities (including eThekwini) baulked at the cost of the new transfer scheme and had been “reluctant to sign user agreements because of concern that the tariff would be unaffordable”.

Our Burning Planet asked Umgeni Water board chair Ziphozethu Mathenjwa whether a final decision had been made about building the uMkhomazi water scheme and how much it would cost. Bearing in mind that Umgeni’s largest customer was losing 56% of its water, we also asked her how national water authorities could justify major expenditure on new infrastructure along the uMkhomazi when most of Durban’s water was leaking, stolen or not paid for?

R30bn-plus first phase

Mathenjwa said no final decision had been taken by the national department as local municipalities and major water users wanted to ensure that the final tab was affordable. She said the total cost remained “a moving target”, while other sources suggest the total cost of the first phase would exceed R30-billion.

Responding to our question about the wisdom of spending billions to top-up eThekwini’s increasingly leaky bucket, Mathenjwa said Umgeni had launched a pilot project to assist the city to trace the worst leaks.

“We think it would be a responsible thing (for eThekwini) to save more water,” she said.

Umgeni’s acting chief executive, Sipho Manana, said there had been top-level discussions between senior government officials, Umgeni and the city to develop a non-revenue water mitigation plan, which included plans to detect and repair leaks.

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The water utility also indicated that a proposed funding model for the uMkhomazi project had been developed by a political steering committee appointed by national water minister, Senzo Mchunu.

“The proposed funding model incorporates fiscal support through 25% grant funding on project costs and a 25% interest-free loan that will significantly reduce the cost of purchasing water from the scheme. The rest of the project cost will have to be raised on the open market,” the utility said in a media statement.

While no firm timeframe has been announced, water planners are concerned that Durban is heading closer to major water shortages unless the leaks are plugged timeously — or the uMkhomazi plan is authorised swiftly.

‘At least 10 years’ before delivery

Technical sources have also warned that even if construction began tomorrow, it would take at least 10 years before any water from the uMkhomazi arrived in Durban.

The national department suggests that water supplies from the Umgeni and Mooi rivers are not sufficient to meet long-term demand in Durban and Pietermaritzburg.

water transfer durban A cross-section view of the 33km water transfer tunnel stretching from Smithfield Dam to Baynesfield near Pietermaritzburg. (Image: Nemai Consulting report)

The uMkhomazi scheme also presents several costly engineering challenges — including the excavation of a 33km underground tunnel stretching from Smithfield to the outskirts of Pietermaritzburg.

water transfer durban Two of these giant mechanical moles/tunnel boring machines will be needed to carve out a 33km-long underground tunnel between Bulwer and Baynesfileld. The machines incorporate a cutter head with an outside diameter of about 4,5m. (Photo: Nemai Consulting report)

The purpose of the tunnel is to allow water to be gravity-fed towards Durban, thereby reducing the cost of pumping water up and over hilly terrain. To achieve this, two massive tunnel-boring machines would have to be installed along the tunnel route to carve away millions of tons of rock.

To provide enough air to staff operating these mechanical moles at depths of nearly 600m below ground level, at least three air ventilation shafts will also have to be drilled or blasted.

https://youtu.be/Bie00h3lxKI

https://youtu.be/sGEMHn01p4g

These ventilation shafts would help to ensure adequate oxygen levels for workers and to dilute exhaust fumes, while also cooling the machinery which generates very high temperatures while digging through rock and groundwater.

At a later point, the scheme would involve building a second major dam further upriver, near Impendle.

Together, the Smithfield and Impendle dams would provide about 1,020ML/day. DM/OBP

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Where Durban’s water goes to