Construction World December 2015

Shemula Water Project – Upgrade: Phase I – Shemula Water Treatment Works

73

voir and the clear water pumpstation and rising main. Phase IB, an EPC contract, included the full water treatment works design and construction. The design of Phase IA was carried out by UWP while the design of Phase IB was carried out by the contractor. UWP prepared a detailed specification for the turnkey tender to ensure that a state-of-the-art facility was provided under the EPC contract. The raw water pumpstation has been designed as a dry well and consists of a 9 m deep x 7 m diameter concrete structure embedded in the left bank of the Pongola River. Generally the flow in the river is kept constant at 5 cumec and is controlled at the Pongolapoort Dam some 60 km upstream. However every September DWS releases a controlled flood peaking at 600 cumec. During the flood the water level rises to within 2 m of the roof of the pumpstation. To allow for a variable flow rate into the head of the waterworks in the absence of a raw water reservoir, variable speed drives controlled by the works operator were installed on the raw water pumpsets. Allow- ance has been made to install larger pumps when the works is increased from 20 Mℓ/day to 40 Mℓ/day. The waterworks layout allows for the smallest feasible footprint. Emphasis was on simplicity of operation, operational control

UWP Consulting was appointed in April 2011 to commence planning of the Shemula Bulk Water Supply Scheme Upgrade, a R845-million bulk water supply scheme to serve 230 000 people in the northern half of the Jozini and Umhlabuyalingana Municipalities. During the preliminary design, the client decided that the water works itself should be let as an EPC (turnkey) tender. Certain elements of the design had already reached an advanced stage and it was decided to split the contract into two sub-phases. Phase IA, a conventional EPCM contract, included the raw water pumpstation and rising main, the clear water storage reser-

and maintenance, high performance effi- ciency and stability together with reliability, flexibility and economy of operation, as well as a pleasant working environment. One of the main design features was using natural slope of the land to eliminate the need for any pumping requirements withintheplantandhencesaveonelectricity. The filters discharge potable water from the clearwell directly into the 2,5 Mℓ clear water reservoir from where a 700 mm dia- meter gravity main conveys water to the clear water pumpstation. The clear water pumpstation, pipework and rising main have been sized to cater for the ultimate demand. Allowance has been made to add a further two pumps alongside the current four when the plant is upgraded to 40 Mℓ/day. The pumps operate at a working pres- sure of 20 bar and deliver water via a 2 500 m long x 700 mm diameter GRP rising main to the existing 4,5 Mℓ command reservoir from where an existing bulk distribution system distributes water. The existing bulk distribution system is severely undersized and in very poor condition and Phases 2 to 6 of the scheme will include bulk pipelines from 700 mm Ø to 200 mm Ø, terminal reservoirs and booster pump stations to supply water to the entire region.

Project information • Comany entering: UWP Consulting • Project start date: 14 October 2013 • Project end date: 10 June 2015

• Client: uMkhanyakude District Municipality • Main contractor: Icon Construction/Veolia Joint Venture • Consulting engineer: UWP Consulting • Project value: R125-million

2 15 BEST PR O JECTS

CONSTRUCTION WORLD DECEMBER 2015

Made with