Monceau-sur-Sambre - Weir
At Monceau-sur-Sambre Ghent Dredging carried out repair works at the downstream side of the weir and its scour-bed.
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The reported damage:
- Rupture of the concrete bottom of the weir. As a result a 3 m deep scour-hole had developed. Along approx. 100m about 800m3 of rip-rap was placed to fill the hole.
- Damage to both banks, consisting of subsidence of both banks.
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The location where the damage has occurred made a hard job to repair with:
- Stricted access by land
- Shallow water and limited headroom
- Huge variations in both waterlevels and flows
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The job in hand consisted of:
- Dredging downstream of the scour area
- Removal of the concrete floor around the scour area
- Filling out the scour area, using armour stones 300/1000 kg on top of a bottom layer of rip-rap 0/180 mm.
- Penetration with colloidal concrete of the armour stones
- Reinstating both banks, using armour stones, concrete and cut-stones.
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To carry out the job a self-propelled pontoon, mounted with a 20T digger, equipped with DGPS was used.
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The pontoon had to be modified several times to be able to carry out the various stages of the contract, i.e. dredging, rock dumping, incorporating concrete and fixing both banks.
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Some quantities:
- 2.300T armour stones
- 400m³ colloïdal concrete
- 300m bank reinstatement
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