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In the Canadian Northwest Territories, a large-scale sediment clean-up project has started.
The project aims to remove contaminated sediment from Mill Lake and its surroundings which were polluted by mining activities in the middle of the last century.
The contractor, Sanexen Environmental Services opted for Damen DOP150 submersible dredge pump to clean the lake bottom and pump contaminated material into Geotubes.
The main challenge of the dredging operations is not the sediment removal itself – dredging at a maximum of 5 meters is no real challenge for the DOP dredge pump.
The real challenge is the debris at the bottom of the lake; branches of all sizes have accumulated at the bottom over the years. When the suction head passes, the branches get stuck in its suction openings. This slows down the cleaning operation.
Yet, as the mesh size of the drag head grid is smaller than the ball passage of the dredge pump, the vast majority of the debris can be removed from the grid.
The DOP dredge pump is connected to an approximately 350-meter length discharge pipeline. This discharge line leads to a dedicated storage area, the so-called Confined Disposal Facility.
Here, dozens of Geotubes are filled with the contaminated sediments and the process water is captured and treated before being returned to the environment.
When the lake has been cleaned, the Geotubes will be covered and capped, ensuring the contamination is effectively contained.