Les Grands Chais de France
XXL siphonic drainage system
The latest XXL high-bay warehouse of French wine wholesaler Les Grands Chais de France in Landiras, Bordeaux towers a massive 37 metres into the air.
The siphonic drainage system which removes rainwater from the 3,045 square metre flat roof in Département Gironde which is heavily influenced by the Atlantic climate is quality German workmanship, made in Rheda-Wiedenbrück.
There is a great likelihood that wine bought by a large German discount chain comes from this high-bay warehouse. One of the largest logistics centres in the French wine trade has been growing here for decades on a site measuring 72 hectares amidst the pine landscape typical for this region. Les Grands Chais de France has a workforce of over 500 people who prepare around 1.3 million bottles every day in the small 2000-strong community of Landiras. Founded just over 35 years ago by Alsace-born Joseph Helfrich, the group of companies is now the second-largest dealer in France and the largest wine exporter in the country. The company now wants to almost double its storage capacity of 22,000 pallets as soon as possible. At the end of March 2014 another section was added to the enormous logistics centre – a new high-bay warehouse reaching 36.75 metres into the sky covered by a massive flat roof.
Just as the Germany love French wine, the French developer appreciates German craftsmanship. He engaged Hammersen Elementbau GmbH based in Osnabrück in Lower Saxony to act as general contractor. In turn Hammersen brought V-Tech Lochmann & Semmelmann GbR on board, an installation company with international experience in high-bay logistics. Rolf Semmelmann: “Cross-border projects require lots of advance planning as a result of the bureaucracy involved, for example every employee and vehicle has to be registered.”
“There is no such thing as the Kostra Calaogue or data from the German Meteorological Service in France to provide information on local rainfall figures”, says Thomas Glunz from V-Tech Lochmann & Semmelmann GbR. “The roof drainage systems therefore had to be calculated using standard values. A figure of 300 l/s was used to estimate the rainfall volume r(5,5) whilst 600 l/s was used for the once in a century rainfall event r(5,100). The entire siphonic drainage system was calculated and designed on the basis of this calculation.
Small number of outlets for lots of rain
12 SitaDSS Profi outlets were used for the main drainage system to protect the flat roof which measures 29.58 m wide and 102.84 m long against the French rain in the Atlantic. As a result of the efficiency of the siphonic drainage system, which operates on the basis of the pipes being filled and creating a vacuum, this rather small number of outlets will be enough to provide the calculated total drainage volume of 90 l/s in the main drainage system. Each main drainage outlet will drain approx. 8.5 litres per second into the ground pipeline almost 37 m below. And if a once in a century rainfall event occurs, a battery of 12 additional outlets of the same type are available, fitted with yellow Sita retaining elements for emergency drainage. Each main drain has an emergency drain next to it which comes into play at a defined retaining height of 55 mm so that the emergency drainage system can remove a further 90 l/s in the event of very heavy rain. The six pairs of outlets, in other words 12 outlets per side, were positioned at the lowest points on the two sides of the flat roof.
Sita retaining units were used to bridge the 120 mm thick heat insulation of the steel trapezoidal plate roof. The planner selected the outlet version with the desired connecting sleeve to provide a secure connection to the 1.5 mm PVC roofing membrane. To ensure that German craftsmanship could be provided here too, personnel from a German company which is active throughout Europe worked on sealing the flat roof. Martin Bonn, Managing Director of Helmut Schmidt GmbH: “The outlets were supplied to the site with connecting sleeves which had been specially manufactured for the roofing membrane type and were then welded by us using hot air to produce a homogeneous material. From our long experience we know that outlets with a foamed membrane flange provide particularly secure connections. In view of the exposed location close to the sea where high winds are prevalent, this is definitely an important additional safety factor.”
Long pressurised pipeline
An effective siphonic drainage system is based on the pipelines being completely filled, in other words a fill level of h/d = 1.0. This is why DSS outlets which are fitted as standard with SitaAirstop are used, to prevent the ingress of air caused by the “Coriolis Effect”. Freed from water and air eddies the completely filled pipeline system can develop the desired vacuum and high suction force which make DSS systems so effective. Function without a collapse in the flow is based on a different view of all outlets and pipe sections in which, for example, parameters such as fall height, pressure loss from friction and flow resistance are also used in the pipeline. The longer a pipeline, the greater the pressure loss. To ensure that the physical conditions can be satisfied, sizes must be selected which have a low pipe friction pressure gradient per metre. The alignment of the 130 metres of flow routes in Landiras required a relatively large size gradient. Whilst the longest flow route was designed to be relatively large, the individual connecting pipelines for the shortest flow route had to be designed in a very small size. To generate suction effects in a siphonic drainage system, the vertical fall pipe, for example, must at least have a size which is less than the horizontal manifold pipeline. On this basis of these hydraulic calculations, a total of 600 metres of PE pipes in diameters from DN 200 to 40 were installed in Landiras.
The two drainage pipelines deliver the collected rainwater down on the southeast side of the logistics building. The rainwater from the main drainage system goes into the network of ground pipes, the fall pipes for the emergency drainage system end 100 centimetres above the ground where they allow the water from a once in a century rainfall event to flow freely onto areas which can be flooded safely.
Pipe installation like a circus high-wire act
As a result of the height of the building, the construction of the wide-ranging pipelines under the insulated trapezoidal steel roof was similar to a high-wire act in a circus. As with any high-bay warehouse, the building shell and roof were install once the skeleton of the building had been erected. Thomas Glunz: “The erection of a high-bay warehouse is like playing with Lego, but on a gigantic scale.” For the erection work the installation team were able to use the basket systems which the logistics team had already installed in the 12 m wide corridors between the high-bay shelving. The cavities between the shelving, measuring approx. 3.4 m in height, were also used as platforms and the erection work was completed by trained industrial climbers who were protected with safety harnesses.
Rolf Semmelmann: “Five metre long PE pipe elements, connected to a fall pipe plunging a good 30 m downwards – that all makes the fastenings extremely important.. Beforehand the system was calculated based on the weight which would be achieved when all the pipes were full. Consideration was also given to the special forces which act on DSS systems. The clips to hold the pipes on the wall were then designed on this basis. They were secured to threaded plates, thick steel plates with a one inch or half inch thread into which threaded rods were screwed. These are special fastenings. We have proof that these clips will hold the system in place even when exposed to the most extreme load case, in other words when the pipes are completely filled.”
The installation work at great height was made easier by the Site fastening system which enables the DSS PE pipes to be installed on a prepared rail system to save time. This system for fastening to a building is also designed to absorb the stresses and movements of a siphonic drainage system and dissipate them safely into the building and roof structures. Because when the water flows into the pipeline system due to the vacuum, siphonic drainage systems tend to develop their own dynamic by oscillation. “Strategically” positioned fixed points at the start and end of each manifold pipe compensate for thermal changes in length – expansion and contraction as the temperature changes.
The incessant heavy rain which prevented the installation work in the first four weeks demonstrated how important an effective flat roof drainage system is in the seaside location of Landiras. But the perfect interaction between the various contractors and the systematic construction of the various system components meant that building project was completed just in time.