The operation consists of the realisation of the transfer networks of the current stations of the village of Robert (Pointe Lynch, Windmill and Courbaril) to the new treatment plant of Pontaléry and the transformation of these respective buffer basins (except Courbaril). The concrete structures will be protected from the aggressiveness of the H2S gas and a nitrate salt treatment will be put in place for each transfer site. A resising of the gravitary networks is necessary in order to be able to transit the effluent in the village of Robert. The creation of the new Pontalery STEP involves the transformation of the various treatment units into an effluent transfer system.