The Tongaat Water Treatment Works (TWTW) was one of the hardest hit pieces of water and sanitation infrastructure in last year’s April floods in KwaZulu-Natal. It resulted in water supply issues for nearly 90 000 people.

By Kirsten Kelly

“During the floods, the Tongaat Dam overtopped, causing substantial damage to the TWTW downstream,” says Bhavna Soni, deputy head: eThekwini Water and Sanitation (EWS), eThekwini Metropolitan Municipality.

The access road to the TWTW (on land owned by Tongaat Hulett) was washed away and no repairs or even a comprehensive assessment of the damage to the treatment works could be done until a new road was built.

Other damage included:

• The motor control centre (MCC) was located underground within the pump house, and both were submerged in nearly 4 m of water – destroying all electrical equipment and damaging mechanical systems like the pumps, motors, instrumentation and control systems.
• A lot of silt and rocks were found in the clarifiers and some of them were severely damaged.
• The head of works channel was significantly damaged and founding material washed away. This channel settled and required significant repairs, including being jacked back into position.
• The floods also caused substantial erosion, resulting in the undermining of the chemical and chlorine building foundations.
• Most interconnecting pipework, cabling and ducting on-site was damaged.

Tongaat Hulett assisted with rebuilding the road and repairing the raw water steel pipeline – which was completed in just over a month. The pipeline reinstatement followed the road repair.

Finding alternative water sources for the area was EWS’s first priority. Three projects were expedited to bring relief:

1. Fast-track the tie-in of the Mamba Ridge pipeline from the Hazelmere Waterworks to the Mamba Ridge Reservoir. Once completed, this resulted in directing 2 Mℓ of water a day from the Hazelmere Water Treatment Plant to some parts of oThongathi.
2. Supplying water from the Belvedere Reservoir (cross connection to Hazelmere System).
3. Laying a water main to the Tongaat South Reservoir from the Nyaninga Reservoir, using eThekwini Municipality’s in-house construction team as far as possible in order to bypass the lengthy procurement process.

Professional team

Section 36 of the Municipal Supply Chain Management Regulations was invoked to speed up the procurement process and acquire funding. Section 36 falls within the Municipal Finance Management Act (No. 56 of 2003), to select who will carry out a particular contract.

eThekwini used a quotation process and a Naidu Consulting/MSW Consulting joint venture appointed as the consultant, Icon Construction was appointed as the contractor, with PCI Africa as a subcontractor for the mechanical, electrical, instrumentation, automation and control work.

The Naidu Consulting/MSW JV did the initial damage assessments and produced multiple options to ensure the restoration of the water supply to the Tongaat area. “We also did a full assessment to determine a baseline for the work that needed to be undertaken to restore the plant to operation, including assessing various approaches to the remediation woks and produced the applicable emergency tender documentation for this contract,” states Devesh Ramghulam, technologist, Naidu Consulting.

105 days

“The repair of the TWTW was completed within the agreed upon 15 weeks or 105 days (from 13July to 27October 2022). To put this into perspective, 9 to 12 months would have been an ordinary contract period for this volume of work. The TWTW repair project ran on the tightest schedule Icon Construction has ever had. Fortunately, we had an extremely competent professional team that worked on the project,” says Peter Hope, commercial manager, Icon Construction.

All investigative work from the Naidu Consulting/MSW Consulting JV was completed days after the flood. Ramghulam adds that everyone (client, consulting engineers, contractor and subcontractors) was available 24/7 to ensure the works were completed on time. “Naidu Consulting placed a full-time design engineer (Devesh Ramghulam) and resident engineer (Neelesh Hira) on-site with process support from MSW Consulting. The client also provided a dedicated, full-time project vmanager (Shalina Ramnund) to fast-track eThekwini approvals and decisions. The entire professional team held weekly meetings to identify project bottlenecks, assess availability of equipment and determine on-the-spot resolutions.”

PCI Africa had the expertise to design and execute all the mechanical, electrical, control and instrumentation work in-house. This made meeting the extremely tight deadline possible, despite some external difficulties. “Globally, the world has been grappling with serious supply chain delivery delays. It is impossible to import PLCs, communication cards and general automation equipment in short time frames. This is caused by the closure of Chinese ports and factories due to Covid-19 restrictions and the Russia/Ukraine war,” explains Lebo Rathebe, proposal manager, PCI Africa.

“To counter this, our in-house electrical and instrumentation design capacity allowed us to remain flexible. We were able to design around equipment that is available, meaning we can present a design that is uncompromising, yet still achievable. Our extensive network allowed us to call on suppliers for assistance and, when coupled with our good relationship with EWS, we were able to acquire all the hardware that was required,” adds Desmond Kopke, electrical engineering manager at PCI Africa.

“Everyone on-site had a mindset and goal to deliver water to the people of Tongaat within the 105-day contract period. We received an extensive amount of support from the Tongaat community and this played a significant role in avoiding project delays,” says Ramghulam.

Hope states that while the project had a high level of political involvement, where the mayor and senior officials from the Department of Water and Sanitation visited the site often, no one hindered the project’s progress.

Repair

The plant was originally constructed by Tongaat Hulett before it was taken over (operationally) by eThekwini Municipality in 2001. In 2014, eThekwini had complete ownership of the TWTW.

“While Tongaat Hulett no longer owns the TWTW, a substantial amount of damage was caused to its own water infrastructure and it has been a huge support in the restoration of the TWTW. In addition to repairing the access road and raw water pipeline, the company allowed a part of the new MCC to be built on its land,” explains Soni.

Designs on foundations of the chemical and chlorine building, as well as the inlet pipe and underpinning, were completed on-site to ensure structures were safe, accessible and suitable for future use. This was done in short timeframes to enable access to other areas of the site. “Due to the nature of the ground conditions and surrounding buildings, heavy vibratory equipment could not be used beneath structures, and therefore applicable concrete underpinning was implemented,” explains Ramghulam.

All six clarifiers were filled with 2-3 m of debris. They had to be drained, cleared of stones and sand, and have mud pumped out of them. “This was a complicated process because the clarifiers are over 9 m deep, the sides are sloped at 60-degree angles, and people had to work inside the clarifiers. The sand filters had to be cleaned and backwashed, and channels had to be cleaned. Most of the digging could not be done by machine because the site was small, so most of the work required a lot of manual labour,” states Hope.

As the TWTW is a few decades old, there was no detailed, updated plan of the layout, which made it difficult to reinstate all of the pipelines. “We were unsure as to what was underneath the pump station and had to figure out what pump went where. PCI Africa therefore had to make changes to some of the pipework,” says Hope. PCI Africa took charge of reinstating or replacing the pumps.“The existing MCC housing the old electrical and control systems, comprising 20 starters, was completely destroyed, and was therefore discarded. All the mechanical equipment had to be removed for inspection. Most of the bigger pumps were repaired while the smaller units were replaced,” adds Rathebe.

Building back better

To avoid damage caused by future floods, a decision was made prior to the commencement of the Contract by EWS and the Naidu Consulting/MSW JV to move the MCC from the pump room to a higher elevation in a separate building, between 55 m and 75 m away. The newly designed and built MCC was installed (as the support work was being removed from the new structure) with the associated electrical and control cabling and racking. The eleven rising main pump sets, backwash pumps, blowers, as well as fans in the pump room are managed from the MCC room – resulting in 15 km of cable being installed. A concrete culvert was constructed to protect the cables that run from the pump room to the MCC, which also expedited the cable-laying activities.

Other protection works included gabion baskets around the TWTW to protect it from future erosion, while a separate stormwater channel was constructed to direct water away from the building. For additional security, a new fence was constructed around the TWTW and existing roads were rehabilitated.

Commissioning

Before commissioning the TWTW, all five reservoirs were inspected, cleaned, disinfected and the water quality was tested. Since the entire system had not been in operation for months, it was therefore expected that there would be multiple pipe bursts once the TWTW was commissioned. However, this did impede efforts to build capacity in the reservoirs. One trunk main and reservoir was commissioned at a time so that the EWS team could focus on a particular zone and immediately resolve any issues that may arise.

Naidu Consulting was actively involved in the commissioning activities and its project team also assisted EWS with assessing the situation, identifying the bursts and fast-tracking the pipeline reinstatement.

“The Hambanathi area had no alternative water supply (other than water tankers) and was therefore the first community to receive water from the newly repaired TWTW. In addition to burst pipes, another challenge was that water demand in the area was high, as community members were storing water. We therefore made the decision to run two pumps in parallel, with a third pump as a backup,” adds Soni.

Another challenge was that the Emona pipeline was old and required extensive repairs. Fortunately, this was resolved because a trunk main at the newly built Emona Reservoir was being built and fast-tracked to replace that old pipeline.

The Mamba Ridge area has also experienced some difficulties, with a suspected burst trunk; however, there is an alternative supply from Hazelmere.

Phase 2

Originally designed for 21 Mℓ/day, the TWTW is currently operating at 14 Mℓ/day. The Naidu Consulting/MSW JV has been appointed to design the TWTW’s functional upgrade. Currently, EWS has limited abstraction rights from the Tongaat Dam, which restricts the plant’s capacity. An agreement will need to be reached between the Department of Water and Sanitation, Tongaat Hulett and EWS to determine the maximum amount of water that can be abstracted for Phase 2 of the TWTW functional upgrade.

Phase 2 will include upgrading the inlet channel, trunk mains and pumps in order to cater for future demand. The head of the works will be upgraded to give better assurances of water quality and how water is channelled to clarifiers and filters.

“While we would have liked to have included this work in the actual repair project of TWTW, we were heavily focused on restoring water supply to the local communities as quickly as possible,” states Soni.

Conclusion

Soni adds that while EWS has experience and expertise in the day-to-day operations of water and sanitation systems, the floods were an unusual event and the municipality was not fully equipped to deal with a disaster of that magnitude. “Going forward, there should be a national disaster management team that has already appointed contractors and consultants as well as funding in place to handle these disasters. If something like this were in place, a lot of the restoration work would have been completed more rapidly. The biggest delay in responding to disasters is a procurement process, and a national disaster management team and our own in-house construction teams can assist with quicker response times.”

“This project is an example of what can be achieved if all project stakeholders work towards a common goal, in this case resulting in achieving the near impossible – the restoration of a treatment plant within 105 days,” explains Ramghulam.

He adds that supplying the community of Tongaat with water after almost eight months without it was something the Naidu Consulting team will never forget. “We are glad to be able to have assisted on this feat of engineering.”

The repair of the TWTW was Hope’s last project before he entered retirement. “While this was a relatively small project (totalling R48 million) when compared to other work that I have been involved in, it was a great last job for me personally, because of its huge impact on people’s lives. The team working on the project were exceptional and the high attendance record and commitment shown on-site by the workforce made the job that much easier.”