Emirates Stadium, North London

Client: Arsenal Football Club
Architect: HOK
Contractor: Rock Asphalte
Type of works: installation of an 1,800m interlinked stainless-steel channel drainage system that removes surface water from the entire spectator entry area.

Emirates Stadium, the spectacular new home of Arsenal Football Club, has ensured that its exposed perimeter and entrances are kept free from standing water by turning to a cost-effective solution developed by ACO Building Drainage and installed by structural waterproofing specialist Rock Asphalte.

Arsenal is one of the leading clubs in world football, and its new home in north London, Emirates Stadium, certainly befits the club’s status. Formerly the location of a waste recycling plant, the 70,000m² site has been transformed into a state-of-the-art 60,000 seater stadium that rises to a height of over 41m. The project was completed on time within its projected 123 week schedule and represents a total investment of close to £390 million.

Spectators arriving at the stadium walk up to a wide, open podium area where all the main entrances and turnstiles are situated. Creating an ideal gathering space for fans before a game - and one that gives unobstructed views of the stadium and the surrounding area - this raised pedestrian area allows the mechanical and electrical plant, as well as a car park, to be located beneath the stadium.

Designed by architects, HOK, the external wall of the main stadium structure forms a perfect ellipse. Running around its entire perimeter, and all at the same level, is the 22,000m² podium. To ensure adequate drainage for the area, the design had specified a run of stainless-steel drainage channel around the entire stadium with separate channel spurs radiating out to edge of the mezzanine. In total, an 1,800m interlinked channel drainage system all finished to the same high specification.

Rock Asphalte approached drainage specialist, ACO Building Drainage, to look at the feasibility of the proposed design and assess if was cost-effective to manufacture and install a channel that would run exactly parallel to the external curve of the building. "Rather than manufacturing a true elliptical channel, we proposed that the run be constructed in short sections of straight channel. Each would be slightly offset to give, over a distance, the impression of a curve," says Martin Fairley, Division Director at ACO Building Drainage. "This approach would not only offer significant time and cost savings during manufacture but also be a lot easier and quicker to install on site."

To prove the viability of the solution, ACO carried out a test to show that a combination of 2 and 3m sections of straight channel could, with the correct offset, produce the smooth, curved finish the architects had specified. The ACO design team had calculated that just a half millimetre offset between each section was all that was required to attain the finish and that this could be readily achieved using a 10mm thick compressible neoprene flange at each section joint. Satisfied with the test site results, HOK and Sir Robert McAlpine gave approval for full system manufacture.

Every channel section is identical - 120mm deep and 155mm wide – and each carries a Load Class C250 perforated stainless steel grating that is fitted with ACO’s Quicklock^® system. This spring-clip mechanism firmly locks the grating into the channel without the need for screws and prevents accidental removal and vandalism. To release the grating, a special tool, which slides through the perforations, unlocks the clip and allows the grating to be lifted.

The system was installed in stages over a seven month period by specialist structural waterproofing contractor, Rock Asphalte. "With the channel supplied to site in easy-to-assemble sections, we were very quickly in a position to achieve the installation rates needed to keep the project on track," says Rock Asphalte Area Manager, Mike Goddard. "This modular approach using straight lengths of channel proved the ideal solution, achieving the exact finish required by the architects."