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storm water sumps in Basement-2, where it will be pumped up to Basement-1 to the storm water outlet pipe.
Water The water system consists of a domestic water feed from council, which then reticulates up the building in a shaft and supplies water to the main domestic water tank on the roof. This tank, which has a volume of 400 000l( 400m 3), can supply the building for up to two days in the case of an emergency.
The water discharged from the water tank reticulates down a shaft and supplies each floor( which consists of two water ring mains supplying either side of the floor).
The hot water plant, which was designed by Spoormaker & Partners, consists of a chiller with a heat exchanger, with backup heat pumps in case the chiller fails. The domestic water tank supplies the hot water plant with cold water and the hot water produced is reticulated down a shaft to all floors. The team also installed a backup booster pump on the council main feed in the event that the council’ s water pressure drops. If this happens, the pump’ s pressure sensor will sense the drop in pressure and the pump will be activated, pumping the water up to the water tank on the roof of the building, which then supplies the hot water plant and all floors.
A grey water tank is located on Level 8 and it collects water from the hospital’ s autoclaves and renal dialysis plant room. This water then gravitates to the first and ground floors to be used to flush toilets and urinals, helping the hospital to save water.
Challenges As mentioned, the one element that was particularly challenging was fitting the drainage pipes in the extremely limited ceiling space and routing the piping around the HVAC ducts.“ These ducts are quite large and because we have sprinkler pipes just below them, it was very difficult for us to co-ordinate around them,” explains Davids.“ To solve this we required intensive co-ordination sessions with all design consultants, and all services had to accommodate one another.” Additional drainage stacks were added where a compromise couldn’ t be made.
Product selection Geberit HDPE was used for the sewer piping.“ Because we had such a confined ceiling space, we required a pipe that would be customisable in regard to its fittings,” explains Davids. PVC piping has fixed fittings and therefore there were many instances where the size and the angle would have compromised the planned drainage route. With HDPE, the fittings are welded together, so the fitting and piping can be cut to the required size and angle, thus giving much more options with regard to routing the piping in confined spaces. The other advantage is that the piping is welded together, which means that there should be little to no leaks over a long period.
Racetrack ward design.
Continued on page 43 >> www. plumbingafrica. co. za February 2017 Volume 22 I Number 12