Difficulties arising from the site
Franki Fondation, working as a sub-contractor of the Fayat Group for building and public works, started work in October 2013. In addition to the tight schedule and to the host of work programmes, the main difficulty lay in the terrain of the worksite where the borers came up against blocks in the moraine. Franki Fondation was in charge of two kinds of retaining walls:
· A temporary retaining wall downslope of the site made with adjoining piles sunk with a hollow auger, with a total of 117 piles with a diameter of 620mm sunk to depths of between 8 and 13 metres.
· A permanent retaining wall upstream, with secant piles using a dual rotation borer (auger and tube), with a total of 180 piles with a diameter of 620mm sunk to depths of between 8 and 14.5 metres.