Close to the "Plage de Marbella" in the south of Biaritz, the local authority built a new sewage treatment plant. A 780-meter-long sea outfall pipeline would divert the treated water out into the Atlantic - far away enough from the beach and the tourists that are the village's main source of income. According to the tender schedule, all construction works for shafts and pipelines have to be completed within 9 months.
An extended AVN1200TB by Herrenknecht with accessible excavation chamber started tunnelling from a 19-meter-deep launch shaft. The cutterhead, with its cutting tools and the cone crusher, were specially adapted to the geological conditions. Polymers were used in order to prevent the clogging of the cutterhead and to support the automatic bentonite lubrication system. To ensure a safe disconnection of the machine from the pipeline during recovery, the first nine concrete pipes (each of 3.3m length) were fitted with steel cores, and reinforced. For the recovery by barge, a seven meters long target shaft was cut in the seabed.