Marine Construction

Deep Sea Cellular Dock – Polaris Mine, Little Cornwallis Island, Nunavut

In the early 1980’s, with an innovative engineering and construction proposal, Tower Arctic Ltd. was awarded the contract to build the Cominco Polaris Mine’s deep sea cellular dock on Little Cornwallis Island. The project included the offshore construction of four (4) – eight five (85) foot in diameter cells, joined by three (3) smaller cells. The eighty (80) foot long sheet piles were driven into the ocean silt below using an internal guide frame and electric vibro hammer.

To achieve our three (3) month construction window, Tower Arctic Ltd. used the Arctic winter cold to construct a seaside ice platform, that was 700 feet long x 200’ wide x 9 feet thick, to work from and that was joined to the existing shoreline on each end. Ice and ocean silt were dredged from the cells core from the ice platform before the installation of a bridge structure to mount a transfer conveyor system. The cells were backfilled with blasted native granular material and once stabilized, the shoreline was pushed out to join the land with the recently constructed cellular dock structure. To complete the installation, a ship loader and insulated conveyor galleries from the concentrate storage facility were constructed.

Under a separate contract with Fisheries and Oceans Canada, Tower Arctic Ltd. constructed and installed a remotely controlled, tidal gauge system to the dock, providing valuable, real time tidal information. Some twenty (20) years later, at the end of the mine’s useful life, Tower Arctic Ltd. was contracted to decommission and remove the complete dock infrastructure to fifteen (15) feet below mean low-tide and to restore the shoreline to its original properties.