Project

Dredging work to remove 230.000m³ heavily and lightly polluted materials. Transport and storage, making heavily polluted materials sample proof (sieve belt filter presses).

Location : Belgium
Client : Haven van Brussel
Contractor : J.V. Dredging International – Baggerwerken Decloedt – Duchène
Period : June 1991 – October 1994
Value : 11 mio Euro

Scope of work

Dredging
Environmental works

General Information

Description of the works

Dredging work to remove 230,000 m3 heavily and lightly polluted dredging materials - class 2 to 5 according to OVAM classification (Belgian Standard) or Class II to Class IV according to 3rd Memo Water Management (Dutch Standard), and transport and storage of the lightly polluted materials and transporting and making heavily polluted materials sample proof (15%).
The bottom surface of the canal to be dredged (14 km long mainly in built up area) was split into zones of lightly and heavily polluted materials following a pre-inspection. The zones were then selectively dredged using environmentally friendly bucket dredging equipment. The heavily polluted dredging sediment was delivered to the quay on mobile sieve belt filter presses where the sediment was made sample proof prior to being removed to class I depositories. The lightly polluted material was removed in elevator bins to a dredging sludge depository set up for this in Ruisbroek.

The unloading of the materials from the transport (elevator bins) was done using patented unloading equipment. This is equipment which scrapes out the materials in the elevator bin using a mobile scraping ladder which transports the materials via a covered shaft to moving roller sieve plant containing a hopper below which a volumetric pump (Putzmeister) was installed. The sludge was thus pumped into the depot through a pipe without the addition of water. The dredging material depot in Ruisbroek was an old, disused sheltering harbour that was set up as a depository. The harbour was filled with an 8 metre thick layer of sludge. A half metre thick layer of sand was sprayed onto this sludge using special sand pumps made up of a network of 200 mm diameter pipes and modified spray heads. Vertical drains for vacuum drainage were introduced into the sludge deposit using lightweight plant and the deposit was then covered with membrane; this accelerated the consolidation of the sludge, which was then rearranged.

Main Equipment

Bucket dredging equipment
Scraping system Eureco