Jones of Oswestry covers all angles in drainage solution for Wembley Arena landscaping
24 January 2007
Jones of Oswestry’s expertise in bespoke drainage has helped to create a dynamic focal point to landscaping at Arena Square, Wembley.
The steel specialist has designed, manufactured and installed a triangular, patterned drainage unit – totalling 55m in length – to frame an impressive interactive fountain.
The innovative landscaping scheme, designed by Randle Siddeley Associates with Laing O‘Rourke as contractor, is part of a major redevelopment of over 70 acres of land at Wembley by Quintain Estates and Development Plc.
The intricately profiled grating, made from stainless steel throughout, fulfils demanding criteria for performance, design and construction.
The hydraulic capacity met performance calculations for the area of free draining specified by the consulting engineers, Buro Happold, and fountain manufacturer, Ghesa.
Extreme precision was needed in fabricating the triangular assembly to ensure it would dovetail with groundworks. Jones’s fabrication expertise also ensured that the position of spray outlets in the grating coordinated exactly with nozzle positions in the pipework beneath.
In line with Construction (Design and Management) (CDM) and Disability Discrimination Act requirements, the grating was designed to minimise any potential hazards to the public.
The frame and drop-in grating sections were precision manufactured to ensure a consistent finished level throughout, and a flush fit with abutting paviours on site. This eliminates the risk of pedestrians tripping over and allows unhindered movement of wheelchairs and pushchairs across the grating. It will also safeguard children or anyone who wants to enjoy the fountain with bare feet.
The recessed design was infilled with granite paviours to give the required aesthetic blend with adjacent landscaping. The ability to maximise paviour coverage around the fountain ensured a non-slip surface. Specialist bead blasting of the steel grating gave the additional reassurance of a non-slip matt finish on exposed surfaces.
The unit’s slip rating was designed and tested by an external laboratory to comply with project safety requirements.
The grating was also designed to be easily removed in manageable sections for maintenance purposes.
The impressive fountain combines water jets, music and lighting, which can be activated by members of the public. Jones also manufactured 10 circular decorative grids, with a 700mm diameter, for the fountain’s integral misting jets.
The grating was engineered for class B125 loads (12.5 tonnes test load to BS EN 124) to accommodate anticipated crowd loadings.
For continuity of quality and performance, Jones of Oswestry’s trend-setting Arborslot recessed tree grids, and Suprabloc recessed access covers were specified for other parts of the £10 million scheme.
Innovated by Jones in the 1980s, the recessed design allows seamless continuation of block paving over access chambers and around tree features.
Chosen for its total service capabilities and technical expertise, Jones provided design, risk assessment, manufacture and installation of the complete steelwork package comprising over 60 products.
The creation of Arena Square formed part of Quintain Estates and Development’s £47million refurbishment of the Grade II listed Wembley Arena.
In all, 70 acres of land around Wembley Stadium is to be redeveloped into a mixed-use quarter providing 6.2 million sq ft of residential, retail, commercial and leisure space, based on master plans by the Richard Rogers Partnership.
Extreme skill is required to assure the dimensional and geometric accuracy of an assembly comprising several hundred frame and grating components. The corner assemblies alone incorporated over 200 different pieces, each individually cut and formed. But when the grating was assembled for pre-delivery inspection at Jones’s factory, it came within a couple of millimetres of the design drawing - well within the 5mm design tolerance.
Designers who attended Jones of Oswestry’s works to view a test assembly of the sizeable grating were impressed with the level of accuracy achieved.
Nick Askew of landscape architects, Randle Siddeley Associates, said: “Jones of Oswestry produced a series of shop drawings for approval and a number of samples for client approval.
“During the manufacture of the grating, our designers met at Jones’ works to review the progress and ascertain the quality of workmanship.
“Very few comments were passed onto Jones at this stage as the grating had been constructed to a very high standard.”
Installation of the complex grating was carried out by Jones of Oswestry’s team of trained fitters.
Installation engineer, Martin Creaven, said: “It was vitally important that the grating was installed flush with surrounding paving as it is likely it will be walked on bare foot by children, in particular.
“We had to make sure the grating was in line with finished levels of granite flooring running up to it, taking into account changes of gradient across what is a very large installation area. We used laser leveling technology to pinpoint and check we were within very fine tolerances of paving levels some 20m away, packing and building up each grating piece on the concrete slab as required.”
The accuracy of the fountain working systems and marble flooring were dependent on the success of the grating, so Jones of Oswestry carried a big responsibility as the grating manufacturer and fitter.
Martin Creaven said: “If we had not achieved the 1mm to 2mm accuracy we did, this would have impacted on other trades.”
Nick Askew of Randle Siddeley Associates said: “From our point-of-view, installation on site went very well. The tolerances required on the concrete sub-base were very high. As a result of the construction methodology used to lay the grating, the two elements interfaced very well.”
Talking about the landscape design, Nick Askew said: “The Arena Square design seeks to deliver a first class setting for the new National Stadium and to create a character of outstanding sequences of major public spaces and high quality routes.
“The aim was to achieve a public space of wide appeal, which is permeable, legible and well managed, and generates vibrancy and vitality in the day, in the evening and at the weekend.”
A detailed concept developed through the design process for the water feature. The specialist fountain contractor, Gesha, was selected to co-ordinate and supply the features within the fountain.
Sketch scheme development of the water feature was through Randle Siddeley Associates, Buro Happold and Pyott Ronson, with specialist input from Gesha. Jones of Oswestry was brought in after the general dimensions and appearance of the gratings had been decided.
Along with other chosen suppliers, Jones of Oswestry spent six months as an integral part of the design consultancy team before starting on production. A design engineer from the company made several trips to Wembley to advise on steelwork design specifications, health and safety, and compliance with CDM and the DDA.