DESIGN, PROCUREMENT, SHIPMENT AND SUPERVISION OF DESIGN BUILD CONTRACT

The Adi Nefas Water Treatment Plant is a design-build contract to produce treated water (to WHO Standards) continuously at the peak day rate of 20,000.00m³ per day.

The main treatment sequence comprises gravity transmission of raw water from the Toker Reservoir to the treatment plant, pre-treatment, metering (partial flume), clarification (lamella plates), filtration and disinfection. The specification for the filters is a dual media (sand and Anthracite) filter type with a loading rate of 9.82m/hr and suitable for a combined airscour backwash (CASBW).

The filter design offered by Paterson Candy was the proven type “K” filter floor designed for combined airscour and backwash (CASBW) and utilising dual media. The “K” Floor is a single suspended slab of reinforced concrete cast in site upon support walls to form a plenum for passage of air and water, the design of the filter required the installation of high-level washout troughs (without dis-entrainment baffles) within the filters at a position, which prevents media loss during CASBW.

Paterson Candy Scope of works included the design, procurement, shipment and site supervision of installation for filter floor materials and special installation tool kit, including the civil structural design for the reinforced concrete filter floor and dwarf walls.