Watering the Soccer City pitch with recycled water

Soccer City Stadium

The World Cup comes to Africa

In 2010, South Africa was very proud to be chosen as the first African country to hold the Football World Cup. Thousands of spectators and visitors, along with billions of television viewers around the world, experienced how the Rainbow Nation provided a vibrant, unique and colourful competition. Who can forget the vuvuzela horns that formed the backdrop to the matches?

Water scarcity
At the same time, South Africa is a water scarce country. Average annual rainfall is around 50% of the global rainfall average, making it the 30th driest country in the world. Some estimates show that South Africa already exploits up to 98% of available water supply resources. In these circumstances, using 26,417 US gallons (100,000 litres) of potable water daily to irrigate the stadium’s football pitch was not desirable. The stadium designers therefore came up with an innovative solution that combined unused infrastructure from the original stadium with the new roof – and new thinking.

Soccer City Stadium and the calabash
The spectacular opening ceremony, the opening match and the final were among the matches played at the Soccer City Stadium in Johannesburg. With a design inspired by the symbolic African pot known as the calabash, the stadium is immediately recognizable with its curved sides and multi-coloured façade tiling made up of 40,000 panels of varying size, colour and texture. In the Rainbow Country, the stadium symbolizes the ‘melting pot of cultures’ that the World Cup brought to life when 32 teams and their supporters arrived in the country.

The solution

Rainwater harvesting

A custom installed rainwater harvesting system, which drains the rainwater from the stadium’s enormous roof area, handles the first phase of the system. This provides the majority of the recycled water, though the system also collects rainwater runoff from the stands and the pitch itself.

80% recycled water
Keeping the pitch in perfect condition requires a lot of water – up to 26,417 US gallons (100,000 litres) a day. The recycling solution implemented in Soccer City is able to fulfil approximately 80% of the demand with recycled water.

Roof cleaning with Grundfos
A total of four Grundfos CR 5-9 vertical multi-stage centrifugal pumps are installed at the upper concourse level of the stadium. They boost the water pressure to the four piped roof wash-down systems, located at the main gutter on the field side of the stadium roof. These systems are utilized to regularly wash the translucent sections of the stadium roof. All to keep the translucent roof clean, all year around.

Reusing infrastructure
Once the water has been used for washing down the roof, it is transported to the ground. Ingenuously, the recycling solution then makes use of disused infrastructure from the original stadium, where a moat had been constructed to prevent the spectators from reaching the field. This moat is no longer required in the Soccer City stadium, so it has been covered with a concrete slab to provide water storage facilities.

The recycling solution implemented in Soccer City is able to fulfil approximately 80% of the demand with recycled water.

3,000 cubic meters capacity
The moat storage facility is able to store approximately 793 US gallons (3,000 cubic meters) of water from both the roof recycling system and the runoff from the stands and pitch itself. A separate basement tank is filled with potable water from the municipal water supply. In times of plentiful rainfall, water is pumped from the moat to the basement storage tank to serve the toilets, maintaining a minimum supply of rainwater in the moat for irrigation of the playing field. The pumps used for this also double as playing field irrigation water supply pumps. In times of limited rainfall, municipal water is used to irrigate the playing field and also to fill the water tank feeding the toilets. Control of the system is automatic, based on water level sensors at various locations.

Domestic water
The domestic water supply to the stadium consists of two components; a potable water system to supply to basins, sinks, showers etc., and a separate water supply system serving only flush valves on toilets. The toilet supply pumps also double as external irrigation system supply pumps, as the irrigation system does not run when demand exists for the toilet pumps. All the pumps are speed controlled, ensuring minimum power consumption while still providing the required flow rate.

BMS controlled toilet flushing
Water saving is taken seriously throughout the stadium. For example, with around 1,100 toilets subjected to peak use over short periods during breaks in events, flushing of urinals is carried out on a programmed basis to conserve water. The Building Management System controls this sequence so that only one bank is flushed at a time, thus reducing peaks in the water flow rate.

The sustainable water reuse solution was the result of a partnership between IZAZI Solutions, MAH Pump Sales and Installations and Grundfos South Africa.

Pumps on display

Glass-fronted pump room

Normally, pumps work behind the scenes, out-of-sight of the many spectators who visit the stadium. Here, though, the distributor thought that the sleek Grundfos Hydro booster systems deserved better – so the two Grundfos Hydro pumps in the building complex are installed in a glass-fronted pump room, giving the spectators the chance to admire them.

Grundfos throughout
Grundfos supplied the pumps for applications throughout the rebuilt stadium. With Grundfos pumps in place, a reliable and efficient water supply was guaranteed for player and spectator facilities, office spaces and business facilities, in addition to the irrigation of the football pitch. Soccer City utilizes the following Grundfos pumps:

* 4 CR 5-9 multistage centrifugal pumps in the water reuse solution

* 2 MPC-E booster systems with 2 CRE 32-5 variable speed multistage centrifugal pumps, controller and tanks to irrigate the pitch

* 1 CR 90-4 multistage centrifugal pump for other irrigation purposes

* Water transfer is handled by one set-up featuring a Hydro MPC-F with 4 CR 45-3 multistage centrifugal pumps and another set-up with 1 Hydro MPC-F with 3 CR 45-3 multistage pumps

* Dewatering makes use of a total of seven Unilift drainage pumps, including the Unilift AP 35B, Unilift CC 9 and Unilift KP 150A drainage pumps.

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