Wiggins Road Water Purification Works

Project Overview: Wiggins Road Water Purification Works was experiencing significant media loss, prompting the need for a refurbishment. ASW Engineering, a prominent supplier of water treatment systems in Southern Africa, was contracted by Umgeni Water to refurbish 12 twin-cell rapid gravity sand filters.

Problem Identification: The initial assessment by ASW pinpointed that the seals between the filter nozzle sleeves and the concrete panels, as well as the sealant used between the precast slabs of the filter floor, had degraded. This deterioration was primarily due to the acidity of the raw water, which leached calcium from the concrete. Such deterioration is a common issue in conventional floor construction, resulting in uneven air scour. This, in turn, caused media loss during backwash and media migration between the slabs into the plenum chamber.

Innovative Solution Implemented: ASW proposed a novel solution involving the installation of Cadar’s corrugated Glassfibre Reinforced Concrete (GRC) panels equipped with nozzle sleeves. These panels were designed to underlay a layer of poured concrete, forming a jointless monolithic floor. The unique construction of Cadar’s nozzle sleeves ensured a superior bond with the concrete, while the GRC panels served as a robust primary seal against the corrosive effects of the raw water.

Guarantee and Outcome: Upon completion of the refurbishment, ASW issued a 15-year guarantee, promising that the rate of media loss would not exceed two percent per annum, marking a significant improvement in the durability and efficiency of the water purification infrastructure.



Monolithic Filter Floor before poring concrete Laying Monolithic Flat floor panels in Rapid gravity filter cell Monolithic flat floor panels installed in rapid gravity filter cell


Monolithic Floor Panels Air Scour test of rapid gravity filter floor Installing Filter Nozzle sleeves into water treatment Monolithic Filter Floor


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