Work will begin in a month in the north of New Caledonia on a port and canal for the 3.3 billion US dollar Koniambo nickel project.
The mining conglomerate Xstrata says a five kilometre channel will be dredged, with a total of eight million cubic metres of sediment to be dumped at sea.
70 people will be involved in the dredging work which is to be completed in November next year.
There has been criticism over the destruction of mangroves in the preparatory phase to build the nickel smelter.
Last month, local truck drivers blockaded the construction site amid claims that they were shut out of possible contracts by outside companies.
Koniambo is scheduled to start nickel production in 2011.