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STATEMENT: Urgent repairs to Nagle Dam‐Durban Heights WTW Aqueduct 3: From Thursday, 7 July 2022
A leak has occurred in one of the four Nagle Dam‐Durban Heights Water Treatment Works (WTW) raw water pipelines, necessitating urgent repairs to be done in order to prevent a potential hazardous situation. The leak is on Aqueduct 3 in the vicinity of Annet Drive, Reservoir Hills, Durban, which has worsened over the past three months, from a drip to a constant flow that is visible to passers‐by.
Similar to the other three aqueducts, this is a high‐pressure pipe that conveys large volumes of water for treatment at the plant. In the interest of public safety and to prevent further water loss, uMngeni-uThukela Water has taken a decision to shut down Aqueduct 3 from the morning of Thursday, 7 July 2022, so that this essential work can be undertaken. In terms of the work schedule provided by the contractor, it will take six days for the repairs to be completed, which includes a day (Thursday, 7 July 2022) for draining and drying of the inside of the pipe. Repair work will begin on Friday, 8 July 2022. uMngeni-uThukela Water has informed Ethekwini Water and Sanitation of the urgent nature of the work and of its duration.
The work was originally scheduled for Tuesday, 5 July 2022, to Monday, 11 July 2022, but was deferred to a later date because of damage to EThekwini Water and Sanitation’s Southern Aqueduct that was caused by an accident at the weekend.
Aqueduct 3 conveys, on average, 180 million litres (Ml/d) of raw water daily from Nagle Dam to the Durban Heights WTW. During the shutdown, there will be a reduction in the amount of treated (potable) water uMngeni-uThukela Water normally supplies to EThekwini Water and Sanitation. Due to reduced volumes of raw water reaching the plant and reduced volumes of potable water being produced during the period when Aqueduct 3 will be offline, it may not be possible to maintain the on‐site Reservoir 2 at a minimum of four (4) metres.
This level is required for there to be sufficient head pressure to supply Ethekwini Water and Sanitation’s reservoirs in high‐lying areas, particularly in the South of Durban. Therefore, consumers in Umlazi, Chatsworth, Northdene and surrounding areas are likely to experience low pressure or intermittent water supply. uMngeni-uThukela Water wishes to apologise for any inconvenience that may be caused.
At this stage, aqueducts 1 and 2, which were severely damaged in the April 2022 floods, remain decommissioned while awaiting completion of repair work on them. As a consequence, uMngeni-uThukela Water is using three and intermittently the fourth emergency shaft pumps to transfer water from Inanda Dam to the Durban Heights WTW. To mitigate possible risk of failure, the fourth shaft pump is brought into use for five (5) days in a week. In the period in which the shaft pumps are used, the full required volumes of raw water reach the plant for treatment; conversely, a deficit occurs in the remaining two days.
At this stage, replacement of the 180 million litres of raw water that will be temporarily lost from Aqueduct 3 is not possible due to implementation of available contingency measures. uMngeni-uThukela Water provides an assurance that everything possible will be done to try to complete the work on Aqueduct 3 within or even before the allocated timeframe. There are significant benefits to restoring Aqueduct 3 in the shortest possible period. This includes increased volumes of raw water being conveyed through it, thereby further reducing the shortfall in raw water. As this deficit reduces, more drinking water will become available for supply to Durban.
Issued by Corporate Stakeholder Management Unit, Office of the Chief Executive
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