During the driving of the foundation piles of the Borssele-Beta, internal grout seals in the pile sleeves broke. As a result, the seal did not seal properly and no sound grout connection could be made.
After an extensive inspection by divers, the situation proved to be rather complex. Not only because of the repair work required and the very limited at the bottom (250 mm), but also because the narrow gap (30 – 100 mm) between the outside of the pile and the inside of the sleeve had become overgrown and clogged with marine growth. So not only the seals needed to be repaired but also all the inner surfaces required extensive cleaning.
After evaluating all kind of fancy HP-water jetting systems, chemicals etc, it was decided to use a simple but effective method: brush all 6 sleeves from the top with divers over a height of approx. 11,20 m ! using small brushes on long sticks.
A DP-2 diving support vessel was mobilized with 2 diving teams for the day and night. In a 24-hour operation, the sleeves were cleaned and temporarily sealed at the top and bottom for many weeks. Then everything was rinsed extensively and inspected by means of very small cameras. New sealing rings were placed on the underside of the sleeves. For this purpose about 25 cm was available to the top of the scour bed and the mudmats.