Articles & Case Studies

Paris fountains get a new lease of life

Posted: Tuesday 22nd May 2012

Entering the pump hall beneath the Varsovie Fountains in the Trocadero Gardens Paris, the first thing that impresses is the myriad colours of the pumps powering the fountains. Most underground pump halls are rather gloomy, poorly illuminated places, but not here. Every pump is colour coded to the specific fountains and displays, with pumps painted lilac, green, yellow, copper, light blue, dark blue, red and gold. Then one has to marvel at how the pumps were installed, as the entrance from the plaza above is extremely restricted and many of the pumps are relatively large.

Featuring a series of basins, cascades and fountains that dominate the great pond, the fountains of the Trocadero Gardens were originally built in 1878, but were rebuilt as the Varsovie Fountains for the 1937 Paris Exposition. Over the past three years, these spectacular fountains opposite the Eiffel Tower have undergone an extensive programme of renovation. The replacement of all the pumps powering the fountains have been central to bringing one of Paris most popular tourism landmarks back to its full glory. Much to the delight of Parisians and tourists alike, the Trocadero Gardens fountains were back in operation in 2011just in time for the French national holiday on the14th July.

The 100 metre long water basin features 12 fountains creating columns of water 12 meters high; 24 smaller fountains four meters high; and 10 arches of water. At one end, facing the Seine, are 20 water cannons capable of projecting a jet of water 50 meters. Above the long basin are two smaller basins, linked to the lower basin by cascades flanked by 32 four meter-high sprays. The volume of water required for all the pumps in the system to operate at the same time is immense, requiring the pumps to deliver up to 8,224m of water an hour. The fountains are operated up to 13 hours a day, but in order to optimise water usage the plumes, cascades, columns and cannons are rarely all run at the same time. The cannons, in particular, use large quantities of water so in order not deprive the other features they are only operated for five minutes at any one time. The pumping system is substantially a closed-loop operation, with water drawn from a large holding tank which is topped up from the City water supply in order to replace that which is lost to the atmosphere. Sets of filters are located in the tank to remove debris that builds up in the main pond and prevent blockage to the pump suction infrastructure.

The renovation of the Trocadero Fountains was long in the planning, stretching back over six years. During this time studies were instigated into the pump types and dimensions required, and programmes costs evaluated and funding raised. One constant throughout this period was the presence of KSB, whose knowledge of the existing pumping system was to be of great importance for the consultants and contractors.

Although various maintenance programmes have been undertaken since 1980, by 2009 only three of the eight pumps were working and many of the fountains, plumes and sprays were blocked. Also the 20 cannons were no longer functioning as these needed a major overhaul.

Since their installation in1984, time had taken its toll on many of the pumps, and they had become blocked and components were broken. Rather than try and rescue these pumps, a decision was taken to go for a complete refit and thereby benefit from the most up to date and energy efficient models available. KSB pumps were chosen based on their proven reliability and robust construction. Together with the cleaning of the fountains, cascades, basins, replacement of the pumps and associated renovation work to the undergrounds pipes, filters and valves, this project has cost in the region of half-a-million Euros.

The eight pumps specified by the project contractor SATELEC consisted of six KSB Etanorm M and RM Series for the overflow, upper plumes, obelisk, cannons, lower plumes vaults, and two Sewatek K Series for the columns and large cascade. The KSB Etanorm horizontal single stage volute pump is very much associated with water supply duties. Providing flows up 792m/hr all six Etanorm pumps were supplied with single mechanical seals mounted on stainless steel shafts and bronze impellers and wear rings. More recognised as wastewater pumps, the two Sewatek pumps are required give a much higher flow rate of up 1908m/hr. These horizontal single stage volute pumps feature a double channel K-type impeller and two mechanical seals that are independent of the direction of rotation. This double protection means that the pumps can operate for long periods, and should one seal fail the pump retains its full operational capabilities.

KSBs role in the projected extended beyond their manufacture and supply of the pumps to site. As has been mentioned already, the access to the pump hall from ground level is extremely restricted, so it was necessary for KSBs service department in France to dismantle the pumps at the ground level entrance and then reassemble them in the pump hall and securely fix them to their mountings. It is all very well to be able to deliver fully assembled, factory tested pumps to a site for installation, but when they have to be dissembled and the components lowered down a staircase well and carried along a narrow passage and then rebuilt in situ, the job is very demanding. This highly specialised job was made all the more challenging because the entrance is on a very busy traffic concourse.

Careful planning and co-operation between KSB and the SATELEC meant that the fountains were turned off for only one month to allow for the removal of the old pumps and the installation of the new ones. With the new pumps installed and all the other major hydraulic components and features fully restored, Parisians and visitors to the Trocadero Gardens will be able to marvel at the spectacular water displays in this city of fountains for many more years.

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August 2021

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