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Drainage & Plumbing

The Sita Siphonic Roof Drainage System “made in Germany” installed in England, draining English rainfall


Standing 38 metres tall, the new Coca-Cola Enterprises Ltd. high-bay warehouse is the current highlight of the extensive construction project in the English city of Wakefield. The installation of a Sita siphonic drainage system for the 6,000 square metre flat roof was a major challenge.

The huge construction of the Coca-Cola Enterprises Ltd. (CCE) plant in Wakefield covers an area equal to 33 football fields, and is the largest and the most environmentally friendly fully-automatic bottling factory in Europe, it is a plant of superlatives. 6,000 cans of soft drinks and 3,200 PET bottles a minute can be produced here. The plant recently became accredited to the Energy-Management Standard ISO 50001 – the first of its kind in the world. Since 2009 the plant has been operating in line with the “Zero Waste to Landfill Principle” by either recycling waste or incineration. The complex was extended in 2013 with a new high-bay warehouse in order to optimise the storage capacity and logistic capability as well as to minimise transportation. The possibility to deliver directly to the customers will save in the future an average of approx. 500,000 miles ( 804,672 km) of road travel per year, in addition to saving the environment a lot of CO2 pollution.

No space wasted
In order to get the utmost out of the new warehouse capacity, the Architects decided to exploit the advantages of a Sita siphonic rainwater drainage system for the 6000 square metre flat roof. This would incorporate space-saving ceiling-mounted horizontal piping set almost parallel to the roof, allowing the maximum height of storage space for the racking.

Frank Birwe, a technical design specialist at Sita Bauelemente GmbH, explains further: “In this way, racking space is not wasted. Another advantage is that fewer downpipes are necessary, and correspondingly, less pipework protection is required, which increases the useable floor area of the warehouse and with fewer downpipes, less underground piping is required and considerable savings in cost and effort are “achieved”

Working in free air
High-bay warehouses have a special construction feature.
The building shell and roof are erected around the already standing racking construction. This poses particular challenges for the installation of the flat roof drainage. Suspended scaffolding, (attached to the track rails of the store-and-retrieve vehicle), could only be utilised in the aisles. The remaining work high above the floor was carried out by experienced industrial siphonic rainwater system installers from the specialist firm V-TECH Lochmann & Semmelmann GbR based in Dortmund. The project leader Thomas Glunz, who accompanied the installation work, said “The Coca-Cola Enterprises Ltd. high-bay warehouse was a very tall building site.

The technicians had to work, secured with harnesses connected to running safety ropes. It was an advantage for them that the pipes were made of polyethylene, and consequently were relatively light to handle, even in 5 metre lengths. Also, the high degree of prefabrication of the mounting system was appreciated by the team under these challenging conditions”. Mr. Cengiz Karadeniz, who is a key-account manager at Sita, commented: “The SitaDSS mounting system has been so designed that the complete fitting of the drainage pipes can be concluded with the minimum use of fixing tools. In a high-bay warehouse, the technicians are dependent on managing with fewer tools.

The workplace is 35 meters above ground and only a limited amount of space is available for tools and equipment”.

On the right tracks
The SitaDSS rapid assembly technology for PE pipes proved itself on site in Wakefield as a dependable support for the installation team. Thanks to the SitaRail mounting rails with the prefabricated clamp pipe brackets, the 300 metres for the main drainage and 340 metres for the emergency drainage were fitted relatively quickly. Now 640 metres of PE pipeline and 32 Sita DSSProfi rainwater outlets are connected together to provide a high-performance siphonic rainwater drainage system which can hold its own against the infamous English rainfall. Because siphonic drainage systems function especially effectively with fully-filled pipes, it is sufficient to employ pipes and formed parts with relatively small diameters – a fact which serves not only the static structure of the building, but also reduces the construction cost.

Siphonic drainage systems are power plants which project water under pressure through pipelines. The mounting of those pipelines must therefore be given a significance which cannot be underestimated. The SitaDSS mounting system, which is typified by pipeline with rail guides and fixed-point fittings on pipes and building parts, holds the ceiling-mounted pipes of the siphonic rainwater drainage system securely at a defined distance from the roof construction. The provision of fixed points which fasten the pipeline at intervals of 5 metres as well as all branches to the rainwater outlets, ensure secure anchoring. Expansion of pipe length, through thermal effects, or sagging of the pipes, is prevented. The so-called “rocking” associated with siphonic systems working with high pressure is avoided by transferring unwanted movements safely into the anchor points.

Rainy, but not intensively rainy
In preparation for the project, the Sita calculation specialists who were to design, with the help of CAD programmes the layout plan of the main and emergency drainage became active. With a calculated rainfall r(5,5) of 320 l/s x ha and a century rainfall r(5/100) of 640 l/s x ha, the location Wakefield in Yorkshire counted as a “rainy” but not “intensively rainy” area. For the main drainage, 16 SitaDSS Profi DN 75 siphonic rainwater outlets with an extension element to accommodate the thickness of the thermal insulation were selected. They feed 183 litres of water every second into the underground drains.

Because the warehouse is surrounded on three sides, the emergency drainage could not be designed with simple parapet spouts. Therefore the emergency rainwater drainage includes 16 further Sita rainwater outlets of the same type which are however equipped with additional accumulation elements for their special task. As soon as the water level, due to extreme rainfall on the roof rises above a defined accumulation height, they dispose the difference between the main rainwater drainage and the emergency rainwater drainage through a special emergency pipeline, which drains freely to an outside area of ground that may be flooded without concern. (It is regulated that emergency drainage systems must be separate from regular drainage systems and that the outflow may not be fed into regular drains).

Every second, the emergency system can swallow up 183 litres of water, resulting in the roof being relieved of additional extra weight. The particular positioning of the new warehouse directly onto the existing building complex made it necessary to find a unique solution to piping the emergency rainwater away. Sita technical specialist Frank Birwe summarised: “Because no free run-off at the lowest-point axis was possible, the emergency drainage pipeline had to be led partially through the forward zone of the high-bay warehouse, this however posed no problem thanks to the horizontal positioning of the pipes in the Sita siphonic rainwater drainage system.“

Conclusion: a “watertight” system
The project in Wakefield was not only about delivering a perfectly functioning rainwater drainage system, but was also about establishing just-in-time international project logistics. The one-stop-one-shop concept of Sita proved to be convincing. From the CAD calculations for the effective Sita siphonic rainwater drainage system, to the Sita siphonic rainwater outlets, the piping, the fittings and everything was “made in Germany – made by Sita Bauelemente GmbH“, at Sita`s plant location in Rheda-Wiedenbrueck.

One of their DSS Siphonic rainwater drainage systems is now taking care of the safe rainwater drainage of the English rain.

Portrait Bernard Rawlings_300 dpi

Bernard Rawlings, Country Manager UK of Sita Bauelemente GmbH, Rheda-Wiedenbrück

Scope: New construction of a high-bay warehouse  at Coca-Cola Enterprises Ltd., Wakefield, Yorkshire, UK

Owners:Coca-Cola Enterprises Ltd. (CCE) Wakefield

Main Contractor: Morgan Sindall


SitaDSS-System with SitaDSS Profi
SitaDSS extension elements
SitaDSS accumulation elements
SitaDSS PEHD pipes and formed parts
SitaDSS mounting system

Manufacturer: Sita Bauelemente GmbH,Rheda-Wiedenbrueck, Deutschland

Contractors: Hammersen Elementbau GmbH & Co. KG., Osnabrück, Deutschland