At Le Crotoy, the Oscar Savreux company uses a STICHWEH bucket wheel to wash and dewater raw gravel transported by a suction dredger located 400 m from the shore. This was put into operation almost two years ago and has the task of picking up the entire 140 ha deposit left on the bottom so that the operator can start extraction in a new area at the end of this large expanse of water. Ultimately, 1.5 million tons of material should be recovered in this way.
The recovery of deposits decided by Savreux, a subsidiary of the Eurovia Group, located in the middle of the Somme Bay Regional Natural Park in Le Crotoy, required the acquisition of two new machines:
- A suction dredger capable of recovering material from depths of over 15 m
- and a large bucket wheel from STICHWEH (E-series, model E 6511 H) to wash and dewater the material before it is transported to the plant via a conveyor belt.
The material extracted from this alluvial deposit, which was formed during the Cretaceous period, consists of 35 % sand, 35 % crushed material and 30% gravel, which has a silicon content of 99 % and very high strength.
Continuity in the work imperative - the suction dredger.
"The resumption is a delicate operation that could only be carried out with a suction dredger," explains Fabien Ridel, operations manager at Oscar Savreux.
"This dredging system was chosen because its operating principle is better than with a grab dredger for recovery over long distances and with large tonnages are well suited.
The dredge, equipped with a jet system, makes it possible to extract siliceous material down to the chalk layer while avoiding chalk mining.
"Oscar Savreux has a strict policy on the quality of its materials, which is why a drill head is only installed when we need to mine at full height," explains Fabien Ridel.