Réalisation de l'émissaire de la Salie au sud d'Arcachon

Construction of a sewage outfall at La Salie, near Arcachon (France)

Ingénieur des Ponts et Chaussées, Direction Départementale de l'Équipement de la Gironde

Abstract

The sewage outfall at La Salie, near Arcachon (France), is the first pier of any size to be built on the Bay of Biscay. The pier is owned by S.I.A.C.R.I.B.A. ("Syndicat Intercommunal du Bassin d'Arcachon") and was engineered by the "Service de l'Equipement de la Gironde". Sea conditions are severe throughout the year and the entire length of the structure is often subjected to strong currents and breaking waves. The offshore part of the 800 m long sewage outfall consist of a 1.50 m diameter overhead steel pipe. The pipe discharges effluent from a paper pulp plant and sewage from neighbouring towns. It is supported every 36 m on steel piles deeply embedded in the sandy sea bottom. The project provides a good example of the use of jack-up barges, which offer a perfectly stable offshore working area and thereby enable construction work to be performed under severe conditions. The works were carried out by G.E.M. Hersent who subcontracted steel structure fabrication and pile driving to C.F.E.M. and Soletanche, respectively.