Hydraulic - France

Seine-Aval treatment plant, Achères

Aerial view of the worksite
Aerial view of the worksite - © VINCI and subsidiaries

VINCI Construction companies have been working for many years at the site of Europe's largest wastewater treatment plant, which treats a substantial proportion of the Greater Paris area's effluents. 

Nitrogen pollution treatment facility
Between 2004 and 2007, a VINCI Construction France led consortium designed and built the nitrification/denitrification unit, which treats nitrogen pollution and improves the quality of water discharged from the plant. It took 17,000 tonnes of steel and 145,000 cu. metres of concrete, cast over a period of 18 months, to build the 50,000 sq. metre plant on a 10-hectare site.

Restructuring of the pretreatment plant
In 2010, a consortium made up of two VINCI Construction France companies - Sogea IDF GC and GTM TP Idf - and Razel-Bec won the contract to restructure the pre-treatment unit for the SIAAP wastewater authority (overall contract value: €230 million). The €110 million civil engineering part of the contract, led by Sogea IDF GC, accounted for five years of work. It called for 27,000 cu. metres of concrete, 3,150 tonnes of steel, 14,000 sq. metres of metal framing and 4,000 sq. metres of wood framing. The new facilities will be handed over in October 2014; overall site commissioning is set for March 2017. 

Biological treatment train 
Meanwhile, in parallel with the pretreatment unit, Sogea IDF GC, GTM TP Idf and Dodin Campenon Bernard, in a consortium with OTV and Degremont, are carrying out the civil engineering works for the plant's biological treatment facilities. The purpose of the new process, called the ""biological treatment train"", is to replace the existing facilities with more efficient units that meet the requirements of the European regulations on good ecological status of water. This part of the Seine-Aval upgrade will take 12 months of design studies (initiated in January 2012) and 40 months of works and will cost €406 million. Work will get under way in the summer of 2013.

70 m3/s is the throughput of the Achères treatment plant, equivalent to one-third of the flow rate of the Seine.

1,000 people will be working on the civil engineering of the plant's biological treatment train. 

170,000 cu. metres of concrete will be cast for the biological treatment train.