The £200 million brownfield Swansea Waterfront re-development, owned by Welsh Water, is part of a wider regeneration of the Swansea Docks in Wales. It required raw sewage to be conveyed down a 14m drop in a constrained space as part of a cost-saving solution within a tight 14-week project window.
“The solution recommended to Welsh Water involved installing the Hydro VortexDrop Shaft in an existing 4m bore access shaft within the dock,” said Len Burgess, project engineer for Hyder Consulting.  “The Drop Shaft takes the sewage 14m from street level down to the existing main sewage line below water level in the dock.
“The Drop Shaft uses a hydrodynamic vortex to throttle back the flow, dissipating the energy of the falling liquid and protecting the surrounding infrastructure from undue stresses. This solution was much more economical in terms of time, space and cost than trying to incorporate a new cascade or other alternative in the dock.”
The Hydro Vortex Drop Shaft from Hydro International is a single-shaft self-activating system with no moving parts, designed to drop water or sewage from heights in a space-saving design. By controlling the flows, the system avoids noise and vibration which could damage the network infrastructure.
In Swansea, the 150mm bore Hydro Vortex Drop shaft is designed for a maximum flow volume of 20l/s. It is sited in a 4m bore foul access shaft which had been located in the dock structure to access the sewage outflow pipeline installed following renewal of the area’s sewage infrastructure in the 1990s.