The Studor single stack solution, incorporating AAVs and P.A.P.A. (Positive Air Pressure Attenuator), has provided the drainage solution for the innovative and iconic 02 Arena in London, UK.
The Millennium Dome, built originally as a temporary structure on the banks of the River Thames for the year 2000 celebrations in Greenwich, has now developed into an amazing permanent venue. Renamed the O2 Arena, it was initially only intended to have a one-year lifespan, but was quickly considered for a long-term purpose. Although the Dome sat idle for six and a half years, it was given a multi-million-pounds injection by its new owners and now ranks among the world’s most exciting sports and entertainment precincts.
The O2 has an overall diameter of 365m, an internal diameter of 320m, a circumference of 1km and is 50m high at its central point.
Apart from the huge music and sports arena with a seating capacity of 23,000, the O2 Arena includes a massive 20,000² feet of restaurants, bars, retail outlets, night clubs and a skating rink. There is also an eleven screen cinema complex, two concert halls, an exhibition space and even an indoor beach, all housed under the huge tented roof.
When at full capacity, the entire building can hold 60,000 people. The O2’s owners, AEG Europe, claim to have alleviated the ‘50-minute queue for the loo’ by installing 548 toilets. And therein lies part of the problem faced by some of the UK’s best plumbing engineers. For the massive redevelopment, the local Greenwich Council dismissed the use of open stacks within the tented surface because of perceived threats of SARS and other airborne viruses.
When it was a temporary structure the arena had open stacks. However, when the entire structure underwent a complete rebuild, due to concerns of the local council of perceived risks from SARS and other airborne viruses, they dismissed the option to use open stacks within the tented area. With this restriction and the design of the structure, this introduced a drainage design problem. Before the Studor single stack solution (comprising of the Studor AAVs and P.A.P.A.) was proposed the only option seemed to be for the drainage ventilation to run to the outside, around 180m away (the equivalent of a 60-storey building) – a costly and time consuming option.
Normally, vent stacks stabilise the air pressure, with the soil stack to maintain it at near atmospheric pressure and help to reduce the incidence of ‘hydraulic shock’, which has the potential to damage trap seals. This can cause them to leak or build-up positive pressures. In extreme cases this can also lead to the trap water-seat blowing out of the fixture and leaking sewer gases into the building’s interior.
The solution to this has been to use Studor AAVs and P.A.P.A. Originally developed for high-rise buildings and comprising a large bladder within a cylinder, the P.A.P.A. unit acts like a shock absorber, dissipating pressure waves and stopping them bouncing around the plumbing system, hence eliminating the need for vent piping and, in the case of the O2, roof penetrations.
The O2 was a difficult project because this was breaking new ground and no typical model existed. By insisting that the waste extraction pipes be so long, gas build-up within the plumbing system when the arena was not in use was a major concern to all parties. Studor, together with ME Engineers and a team at Heriot-Watt University in Edinburgh, Scotland (led by Professor John Swaffield), worked to develop a suitable system for the O2 Arena and to prove to Building Control that the system would work. The data produced by the group included flow calculations, flow rates and pipe sizing to deal with air and transient pressures. The university team determined that any gas build-up would follow the water flow. By placing all urinals on a twelve-hour flush cycle they greatly alleviated the potential of any gas build-up problem.
Inside the Dome the full drainage and ventilation system is sealed. However, outside pump stations are on pillars with open vents that are spaced 300 metres apart to dispense any odours are generated within the complex. All vertical stacks are cast iron, with only a few waste pipes being plastic. No expense was spared on the system, with some pumps costing more than £1 million!
The O2, a world-class music, entertainment and sports venue, was re-developed with the world's first sealed drainage system, totally without the need for any open vents. This maintained the integrity of the clean lines of the iconic dome roof, reducing environmental impact and cost by way of a significant reduction in materials and labour, as well as providing a drainage system capable of fully functioning under the peak demands of the complex when filled to capacity. This was only made possible through the installation of the Studor single stack solution, which comprised of the Studor Mini-Vent, Studor Maxi-Vent and Studor P.A.P.A.