Construction World December 2023

CIVIL ENGINEERING CONTRACTORS

PRETORIUSRAND 20 Mℓ RESERVOIR

I n recent years, unreliable access to clean drinking water has not only provided endless frustration for everyday South African citizens but it has now begun to affect the country’s economy and the health of its citizens. Whilst not facing the water scarcity problems plaguing provinces like the Western Cape and Northern Cape, Gauteng’s aging water infrastructure has struggled to keep up with potable water demands simply due to the swift growth in demand that accompanies rapid urbanisation. Consequently, municipalities and developers have begun to partner together to meet the province's growing demand. The Pretoriusrand 20 Mℓ Reservoir project is one such example displaying the success of this partnership. Having recently pioneered the first prestressed, round reservoir floor in Africa at the Khutsong 30 Mℓ Reservoir, Quantibuild was eager to repeat the innovative application’s success at the Pretoriusrand 20 Mℓ Reservoir. Whilst the

Khutsong Reservoir floor was designed as a 450 mm thick raft slab given the dolomitic founding conditions, the Pretoriusrand Reservoir site offered no problematic founding conditions, and therefore the basis for an alternative prestressed floor would have to be in terms of both quality and economy. The case for end product quality of a jointless floor in a water-retaining structure was an easy sell given the short-term and long-term issues often caused by floor joints in reservoirs. Additionally, eliminating the jointing products and the entire underfloor drainage system provided savings that could be used to offset the additional costs of prestressing. The significant reduction in reinforcing steel from prestressing however provided substantial savings and made the alternative economically appealing. One of the key requirements for the alternative floor slab is that there were to be no stress raisers under the floor slab

16 22 nd Best Projects Awards 2023