Water & Wastewater Treatment

PUMPS AND PUMPING SYSTEMS impeller pump where the impeller is located in a tubular casing immersed in the water. Explosion protected to ATEX II G2 T3, the pump has a maximum flow capacity of up to 7,000l/s and a maximum head of 12m. Low vibration hydraulics and a vortex-free flow due to the inlet ribs and wide bellmouth ensure that the pump is hydraulically optimised. Operating efficiency is provided by the slim motor that minimises discharge tube flow losses. From the outset of its involvement in the project, KSB recognised that its responsibilities would go far beyond merely supply and installing the required number of pumps. Technical adaptations to the various pumping stations would be necessary in order to provide optimum performance for the pumps. Examples of this include: • • • Extending La Fosse PS to increase drainage by a further 3m³/s Planning and equipping a new PS at the end of the Canal de Capette to increase drainage by a further 9m³/sec Refurbishing the PSs at Souteyranne/ Mas Livers, La Cave/Le Mole, Sylvéréal and Bourgidou/Aigues-Mortes in order to adapt to their new drainage volumes "The floods covered 30,000ha, caused damage worth an estimated £250M million and took more than three months to pump clear." Counting the cost of flooding The Petit Camargue lies in the Languedoc-Roussillon region of southern France, between the Mediterranean Sea and the right side of the Petit Rhône, one of the two arms of the Rhône River Delta. Covering an area of 55,000ha, of which 38,000ha comprise wetlands, the Petite Camargue is largely given over to agriculture and fisheries, whilst its very special flora and fauna make it a haven for wildlife and tourism. With large areas of the Petite Camargue lying some 2m below sea level, it is prone to regular flooding, resulting from the rising levels of the rivers Vistre, Vidourle and Rhône, and sometimes by breaks in the dykes. The earth of the wetlands is naturally saturated so in the event of great floods, when water courses rise above river and drainage channel banks, some 300km² of the Petite Camargue can be transformed into a massive overflow area. Basically, this means that the water gathers here until it flows or drains off again, a process that can take a considerable amount of time and at a considerable cost to the local communities. Drainage As land reclaimed from the sea, the Petite Camargue has been drained, both manually and by drainage structures for several centuries. In the more Each PS had its own special requirements, which in certain cases required KSB to simulate flow conditions to evaluate and test its civil engineering structures in order to ensure that the pumps would fulfil their duties. At Sylvéréal, it was necessary to construct special inlet u 25 recent past, pumping stations (PS) have eased the burden, with the flood water being initially pumped from the flooded areas and then fed into the Rhône where it flows into the sea. However, in the past 20 years, these PSs have proved to be inadequate when put to the ultimate test. Intense flooding occurred in 1993 and 1994, and as a result a special body, Syndicat Mixte de la Camargue Gardoise (SMCG) was established with the eight communities affected to address the problem. Eventually in 1998 a further public body was created to thoroughly investigate how to reduce the risks of flooding, with the results expected by 2003. However, in September 2002, flooding of the Rhône upstream occurred and this had a serious effect on the region. This was followed in December 2003 when flooding on the Rhône and its main tributaries took on considerable, even historical, dimensions. Evacuation In the lower course of the Rhône, which runs in part along the Petite Camargue, 2003 was the third-largest known flood, even greater that the two floods of 1840 and 1856 which had massive effects on the region. In Beaucaire, which is situated several kilometres north of the Petite Camargue, floods peaked at 11,500m³/s. In the lower course of the Rhône it took several days, in some parts even several weeks, before the water flowed into the sea. Some residential areas were 4m underwater and, on both sides of the river, 32,000 people had to be evacuated. The floods covered 30,000ha, caused damage worth an estimated £250M and took more than three months to pump clear. Engineering work being undertaken at Sylvéréal. January 2014 Water & Wastewater Treatment 23

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