In 2019 we laid the foundations of the pontoons for the development of the Eric Tabarly promenade, which runs along the magnificent lake of Enghien-les-Bains. Placed on more than 150 screw piles, the pontoons are made of aluminum with an oak floor. In order to avoid contact between steel and aluminium, neoprene plates were used. During the work, despite the favorable geotechnical study, we discovered premature refusals, which we initially took for a stonework. The study of the city archives has shown that it is an old quay, made with cobblestones, built at the beginning of the 19th century, and covered with embankment during the 20th century because of the rise of the lake level. We managed to preserve the old work, placing the piles in a timely manner and without causing as much damage as possible.