With three repairs in three years, the 1964 drinking water pipe located under avenue Professor Charles-Foulon in Beaulieu, in Rennes (Ille-et-Vilaine) was showing serious signs of fatigue. Classically, it should have been completely changed. The ground would have been ripped open, and a 700 meter long trench would have had to be traced. This time, the Rennes Basin Water community has opted for an innovative solution.
An inflated sheath inside
The pipe will be repaired from the inside. The principle? Four introduction pits or wells were opened at four different points. After mechanical cleaning, a fiberglass and resin sheath is pulled. Then, using a compressor, the flat sheath is inflated to stick to the walls of the tube. It remains to pass “a little train of ultraviolet lamps” which will heat (polymerize) and solidify the whole, without altering the drinking water which will soon pass through it. The operation carried out by the company Axeo TP is called lining. “Once finished, it will last for at least fifty years!” » assures the manager. The work will be completed on December 10, 2024.
Trees preserved
It is impossible to pull a sheath of this type over the entire pipe. The work, which began at the end of September, will be carried out in three segments. “One of 100 meters and two of 295 meters which for this technique constitutes a record in France”, argues Maxime Aubeaux of the Rennes Basin Water community.
Another advantage: the fairly recent cycle paths are little damaged and above all the numerous plane trees lining the avenue have been preserved. The operations do not affect the root system at any time. However, this new, more gentle technique, which also has the advantage of reducing the carbon footprint, cannot be reproduced everywhere. It can in fact only be carried out on sections with no or few connections.
France
