WATER & SANITATION

Development Organisation) have collaborated to build and operate a RemixWater demonstration plant at eThekwini’s Central Wastewater Treatment Works at no cost to Council. The demonstration project compromised a 300 m3/day containerised unit and a 6 250 m3/day demonstration plant. The construction of the plant was completed in February 2020 and was severely affected by the COVID-19 pandemic. The plant was successfully recommissioned in August 2021 and was operational until February 2022; operational results were recorded and met potable water standards.

2020/21 projects completed

Zwelibomvu Inlet Phase 1: Zwelibomvu 2 Reservoir is supplied via an existing 300 mm diameter gravity main from Shongweni Reservoir. Two types of pipe material were used for this pipeline, namely steel and fibre glass. The fibre glass section has become brittle over time and is resulting in numerous bursts which require constant repairs. This pipeline also has insufficient capacity to cater for future demand and needs to be upsized. This project is for the construction of a 3.6 km long 500 mm diameter welded steel branch pipeline to the existing Zwelibomvu 2 Reservoir.

Maphephetheni Augmentation Project (Phase 1 & 2): The upper and lower Maphephetheni areas, located in Ward 2, north-west of Durban were designed to be supplied by Mkhizwana Water Treatment Works (MWTW). Over the years, the demand for water supply in these areas has increased, gradually putting strain on the limited supply from the MWTW. EWS therefore proposed to augment the supply into the area via gravity feed to pump water to a reservoir zoned for high-level areas. Phases 1 and 2 are complete.

Inlet to

Hammarsdale Trunk

Main: The demand at the Hammarsdale High Level Reservoir is projected to increase from 7.7 Mℓ/ day to 13.9 Mℓ/day in 2036. In order to meet this projected demand, a dedicated inlet trunk main from the recently constructed Western Aqueduct is to be constructed. This contract is for the construction of a 1.5 km long 500 mm diameter welded steel branch pipeline from the Western Aqueduct to the existing supply pipeline to Hammarsdale Reservoir.

Redcliffe Valleyview Drive Trunk Sewer: The project entailed construction of 860 m of 355 mm diameter trunk sewer to serve 720 units from the Redcliffe housing development and surrounds. This includes gabion protection works and manhole construction. The project was completed in October 2021.

Kingsway 2 Rising Main: The project entailed the construction of approximately 40 m of 400 mm diameter steel sewer pipelines that will tie into the existing Kingsway 2 rising main within the Kingsburgh area located in Ward 97.

Select projects under construction

Shongweni Reservoir: The Shongweni Reservoir supplies the existing Shongweni zone and the Zwelibomvu, Ofudu, Clifton and Salem reservoirs downstream. The wider increase in water demand has resulted in supply constraints due to insufficient onsite storage. The objective of the project is to increase storage capacity at the existing Shongweni Reservoir, including the construction of a 6 Mℓ reinforced concrete reservoir and ancillary works. Replacement of Water Pipes in Chatsworth

Reservoir 4 Zone: The objective of this contract is to assist the Municipality in its objective to replace approximately 2% of existing water mains year-on-year in critical reservoir zones within the eThekwini Municipal Area. The expected outcome of this programme is that the budget provided in respect of each financial year will be spent on replacing water mains in accordance with the critical reservoir zones identified.

Emona Reservoir: EWS identified the need to increase the storage at the existing Emona Reservoir, in order to accommodate the increase for water demand in the area, which is due to growth in the supply zone, including the proposed Sunhills development. The project includes the construction of a 5 Mℓ reinforced concrete potable water reservoir and a 15 kℓ elevated steel tank, among other associated infrastructure.

Kweqetho Reservoir: The need to increase storage at the existing Kweqetho Reservoir was identified in order to accommodate the increase for water demand in the area. This project entails the construction of a 6 Mℓ square, reinforced concrete reservoir for the storage of potable water, as well as all associated works.

Ntuzuma B Sewer Reticulation: This project is required in order to complete the waterborne sewer reticulation in the Ntuzuma B area. The project entails the construction of approximately 5 500 m of sewer reticulation of 160 mm diameter pipe, as well as 205 manholes and nine road crossings in Ward 45. Ntuzuma Sewer Reticulation: This project, broken into localised contracts for various areas within Ntuzuma, entails the construction of extensive sewer reticulation throughout the township. Residents in the area are dependent upon on-site sanitation, such as pit latrines, septic tanks and conservancy tanks. The provision of a waterborne sewer system is required to eliminate the pollution risk posed by the current on-site sanitation.

Inanda B Sewer Reticulation: The project entails the construction of approximately 2.7 km of 160 mm diameter sewer pipelines, tying into existing waterborne sewerage network within Inanda B of Ward 107, for the provision of sanitation services to approximately 118 households.

Mkhizwana WTW Capacity Upgrade: The existing Mkhizwana WTW is located in the Valley of a Thousand Hills and receives raw water from the Nagle Aqueduct. It has a design capacity of 1.3 Mℓ/day, based on slow sand filter technology. Currently being serviced by a temporary package plant since 2018 due to vandalism of the plant during service delivery protests, the works is being upgraded from 1.3 Mℓ/day to 4 Mℓ/day capacity. The project commenced in September 2021 and is due to be completed in September 2023.

Ogunjini WTW upgrade: The existing Ogunjini WTW, which is located alongside the Mdloti River in the rural area of Iqadi north of Verulam, receives raw water from this river and has a current design capacity of 1 Mℓ/day, based on slow sand filter technology. The proposed capacity increase will comprise a new abstraction pumping system, inlet works, pre-treatment comprising flocculation and clarification, balancing tank, pressure filter units, storage reservoir, hypochlorite dosing unit, clear water high-lift pumps and sludge dewatering unit. Construction work for the upgrade commenced in September 2021.

Hammarsdale WWTW Improvements: The existing Hammarsdale WWTW, which is located in the Hammarsdale area in the Inner West and receives wastewater predominantly from the surrounding industries, has a design capacity of 27 Mℓ/day based on the extended aeration activated sludge process. However, the very high chemical and organic load over the years has resulted in this plant being derated to approximately 9 Mℓ/day. The proposed improvements will comprise a new inlet works with mechanical coarse, fine and ultrafine screens, grit removal facility comprising induced vortex Pista grit traps, new 27 Mℓ/day raw sewage pump station (to replace existing), new sludge dewatering facility designed for four solid bowl decanter centrifuges, as well as new medium- and low-voltage electrical infrastructure. The estimated cost of the project is R170 million (currently on hold due to budget reprioritisation due to flood damages).

Special mention: Tongaat WTW

The Tongaat WTW was severely damaged by the flooding of the Tongaat Dam in April 2022. The road to the WTW 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.

What followed was identifying the need for the emergency remediation and operationalisation of the WTW. Requiring work that would normally take between 9 and 12 months, the various stakeholders involved came together to realise a highly impressive feat of engineering by getting the Tongaat WTW up and running within 105 days. Extensive works were also undertaken to ensure that similar events may be avoided in the future.

After: The repair of the Tongaat WTW was completed within the agreed upon 15 weeks or 105 days (13 July to 27 October 2022)

Before: The motor control centre (MCC) of the Tongaat WTW was located underground within the pump house, and both were submerged in nearly 4 m of water

Supplier

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