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Europe's Largest Water Treatment Plant Utilises DSM's Composite resins

27 May 2005

A construction project is underway in the Netherlands to build Europe's largest water treatment plant which includes GRP pipes and DSM's Synolite and Atlac resins.

The new plant will be built close to the cities of Delft and Rijswijk and includes a run of 450 metres of filament wound GRP pipe for effluent and hot air pipelines with a diameter ranging from 125mm up to 2 metres.

The 2 metre pipes were manufactured by the specialist producer Nsguassero SA using DSM Composite Resins’ Synolite 0266-N-4, standard isophthalic acid based unsaturated polyester resin combined with a flexible liner based on Synolite 0268-N-4. The relatively low peak exotherm of Synolite 0266-N-4 makes it possible to wind pipes in one go without the exotherm levels getting too high, with the consequent risk of delamination. Pipe wall thickness varies from 20 mm for the wound pipe, up to 60 mm at points where direct connection to the pumps have been laminated onto the main pipe. Versteden Leidingsystemen B.V., is delivering and installing pipework for this part of the project as a turnkey operation.

The main contractor for the project is BAHR Consortium vof, and one of the engineering companies active on the project is OTV Rossmark AHR v.o.f.

Mr. Olivier Vermes of OTV remarked: “originally, some pipelines were designed in coated carbon steel or stainless steel, but calculating on an operational life of 30 years, GRP pipes based on Atlac and Synolite resins were considered ultimately more suitable for the project. GRP piping systems do not suffer from typical steel corrosion problems, meaning much lower maintenance over the total operational period. Another advantage was the intrinsic flexibility of the GRP pipe joints, so if we need to replace valves in the future, this can be done without taking extra measures.”

The project, on a 30-year concession, includes the design, construction and operation of a new wastewater treatment plant (Harnaschpolder WWTP) with a capacity of 1.3 million population equivalent, as well as the refurbishment and operation - in order to comply with more stringent discharge requirements - of an existing wastewater treatment plant (Houtrust WWTP, with a capacity of 0.4 million population equivalent.

Delfluent, a consortium of five companies, has been commissioned by Delfland District Water Authority to build the new and to renovate the existing wastewater treatment plant. Construction work started at the end of 2003. The two projects will be handed over in mid 2009 and will then remain under Delfluent's management until 2033.

Total contract value over the 30 year concession is EUR 1.58 billion. Not surprisingly the project received the European Water Deal of the Year 2003 award from Euromoney's Project Finance Magazine. And being the largest European PFI transaction in the water sector, the project was referred to as a landmark deal.

The pumping buildings and (biological) water treatment basins are made from concrete structures, but GRP pipelines are necessary to transport the treated and untreated water, and to carry hot air to the biological cleaning process. The first GRP pipeline has now been installed and will be connected to the five large effluent pumps, with a total capacity of 40.000 m3/hr, with 3 out of 5 pumps (the remaining 2 being stand-by pumps), that will be used for the transport of the cleaned effluent to the North Sea.

Later this year, a further 400 metres of GRP pipe, varying from 125 mm to 800mm in diametre, will be installed to secure the hot air supply to the eight biological treatment tanks. Since the operational temperature will be 114°C, a more temperature resistant resin type was required. All hot air pipes will therefore be produced using Atlac 382 Bisphenol a based unsaturated polyester, to ensure reliable operation in these more aggressive conditions.

The Image shows a 2 metre diameter header section of GRP pipe, showing the connections to the pumps.






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