DAMS & RESERVOIRS
Automatic control valves regulate the levels Amanziflow Projects’ pressure-sensitive, purpose-designed diaphragm valves (DVs) open and close intuitively to keep reser voir levels and water system flows constant. By Peter Townshend*
T
he programme for the City of Mthatha’s bulk water conveyance master plan star ted in 2012 within the O.R. Tambo District Municipality, as well as the surrounding villages. This entails the construction of a new bulk water supply system, including rising and gravity mains, as well as reser voirs to transfer the clear water pumped out of the Thornhill and Highbur y water treatment works (WTWs). The review, design, project management and implementation phases were awarded to GIBB consulting engineers. The implementing agent is Amatola Water. There are 25 concrete reser voirs ranging in size from 0.5 Mℓ to 12 Mℓ in capacity positioned in rural settings, some in remote areas. Each reser voir required self-regulating inlet control valves that open to fill and close off when full. Amanziflow Projects’ locally
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IMIESA January 2021
developed and manufactured DVs by were selected because: • They do not require any external electrical source or telemetr y to operate them. • They will close off when the reser voir is full to prevent over flow and will open automatically as the water level drops to fill the reser voir. • They close over a short period of time
Large 1 350 mm diameter DV as a dam outlet at Ncora Dam, Eastern Cape
to prevent water hammer surges in the pipelines. • They are totally submerged inside the reser voir to prevent vandalism. • They are cost-effective and are supplied in sizes from 150 mm to 400 mm, as
