Engineering and environmental consultancy SSI will, this month, complete the commissioning of a 13 Mℓ/d extension module, at a cost in excess of R17-million, at the existing Sundumbili water treatment works (WTW), which treats water drawn from the Tugela river, in KwaZulu-Natal (KZN).

The extension will increase the treatment works’ capacity from 27 Mℓ/d to 40 Mℓ/d.

The treatment works currently serves the Sundumbili township, the Isithebe industrial estate, the Inyoni housing project and the rural areas surrounding Sundumbili.

Following the bulk infrastructure upgrades, it will also serve the Mandeni, Tugela, Macambini and Tugela Mouth areas.

The upgrade entailed the construction of reinforced concrete water-retaining structures, as well as the supply and installation of mechanical and electrical equipment for the new module.

SSI water engineer Gordon Druce reports that, in April 2008, the iLembe district municipality contracted SSI to extend the treatment works to meet the demand for additional water supply to the areas surrounding Sundumbili and Mandeni as part of the municipality’s service delivery drive.

The consultancy undertook the design of the new module, its structural and hydraulic design, preparation of the tender documentation for civil works, the design and supply of the mechanical and electrical equipment contract, as well as contract administration for both the civil contract and the mechanical and electrical contract.

A number of subcontractors were instrumental in completing the extension project.

The main civil contractor was bpb Sindi Civils, which was responsible for the earthworks, reinforced concrete structures for sand traps, the flash mixer, clariflocculator, filters and filter gallery building, the interconnecting steel pipework and site drainage and site works.

Mechanical and electrical contractor WPCP was responsible for the design of the water treatment process and the mechanical equipment supply thereof, while subcontracting electrical company Electron was responsible for the design, supply and installation of the electrical equipment.

JC Martin Surveys conducted the engineering survey, while Geosure conducted a geotechnical investigation.

C&M Safety Consultants conducted the necessary health and safety audits on site, while Environmental Planning & Design was the environmental control officer.

“The coordination of multiple contractors with interdependent programmes, as well as an initial delay in the award of the civil works contract, proved challenging, but was overcome through regular project management meetings with the client, as well as regular site progress meetings,” says Druce.

The project also includes the bulk distribution aspects of the water supply scheme, the designs of which are now under way, to enable the effective distribution of the water.

This bulk infrastructure includes the construction a 10 Mℓ reservoir, a 5-km-long 600-mm-nominal-diameter bulk gravity main, the upgrade of a pump- station and rising main and the construction of a 5 Mℓ reservoir at Rocky Ridge, in Mandeni, from where the bulk distribution to the future supply areas will be undertaken.

The Sundumbili water treatment works is Blue Drop- accredited for high-quality drinking water as outlined by the Department of Water Affairs.

To acquire Blue Drop status, a water system must have scored 95% or more when assessed against the Blue Drop requirements, which look at not only drinking water quality compliance, but also the overall management of the drinking water system.

The plant operator, Water & Sanitation Services South Africa, is working hard to maintain this status, says Druce.

Once commissioned, the municipality will be able to provide more people with safe drinking water and will create a redundancy in the water treatment process by ensuring sufficient potable water supply to the areas.

Meanwhile, SSI reports that the construction of the Waterloo reservoir, at a cost in excess of R16-million, in the north Durban corridor area, between Umhlanga Ridge and King Shaka International Airport, was completed in November 2011, with the final inspection still to be conducted.

The construction of a 15 Mℓ reinforced concrete reservoir will increase the storage capacity at the existing 10 Mℓ Waterloo reservoir site.

The reservoir currently supplies the areas surrounding Waterloo and Blackburn, in KZN.

The Waterloo site is currently supplied by water from the Hazelmere WTW. However, the Northern Aqueduct pipeline system, which is currently in the design stage, will extend to the Waterloo site and ensure the area is supplied from the proposed Western Aqueduct pipeline, which will be supplied from the Midmar WTW.

The eThekwini Water and Sanitation division contracted SSI to undertake the detailed design, structural design, tender documentation preparation and project administration.

SSI states that, if demand in the area increases in future, there is available space at the Waterloo site to accommodate a further 10 Mℓ reservoir.

Meanwhile, the Umtamvuna WTW pumpstation and storage dam were recently upgraded.

The Umtamvuna WTW serves a large area in the southernmost region of the Ugu district municipality.

Areas supplied with potable water from this facility include the coastal strip from Port Edward, in the south, to Ramsgate, in the north. It also serves the rural and semi- rural Izingolweni, Vukuzithathe, Nzimakwe and KwaXolo areas.

The longer-term water service planning makes provision for pumped water to be extended beyond Ramsgate to supply Margate as well, says SSI water engineer Rowen Clark.

It is reported that 24 255 households will benefit from the upgraded system.

The project objectives included the replacement of the ageing and leaking existing pipeline with a 800-mm-diameter, 2.1-km-long welded steel pipeline as well as the replacement of low-lift and high-lift pump sets to double the rated capacity of the river abstraction works to 40-million litres a day. This undertaking also required increasing the capacity of all the delivery pipework, as well as the electrical power plant and all ancillary equipment.

By filling the 172 Mℓ raw water storage dam, the Umtamvuna WTW has a ten-day guaranteed water supply in peak periods and a 14-day water supply in off-peak periods.

The pumps are also able to operate in line with State-owned power utility Eskom’s programme to reduce energy consumption, which translates into a saving of R2.4-million a year, notes Clark.

SSI undertook the project engineering, while Shulu Construction was awarded the steel pipeline contract and PCI Africa was contracted to complete the pumpstation upgrade.

Construction started on the new pipeline on March 3, 2009, and the first high-lift pumps started filling the dam on August 27, 2010 with the final project handover taking place on November 30, 2011.

Umtamvuna works manager Charles Thorp says that, when consulting with clinics in the area, it was noted that there was a significant decrease in the infant mortality rate owing to the fresh water supply to the previously marginalised rural communities.

The construction of the new pipeline proved significantly challenging, owing to the treacherous mountainous terrain; the weight and size of the pipes, which required the use of 30 t excavators; and environmental considerations, which had to be considered before the final pipe-laying could take place.