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Rock Islands

The Rock Islands have been designed to prevent out of control shipping vessels from running into one of the main span tower piers. The rock island works to stop a ship before it ever hits the tower by causing it to run aground. Each rock island is approximately one acre above the water and extends down to five acres across the bottom of the riverbed. They are constructed with three sizes of Newfoundland limestone.

The bases of the two rock islands are constructed with twelve shiploads of small Newfoundland quarry stone. It took six days for the stone to travel from Canada’s most easterly province. When it arrived in Charleston, the stone was loaded into one of two different types of barges depending how it was to be used to form the island. Stones placed on “bottom-dump” barges were released directly into the river to form the perimeter of the island. Stones placed on “flat top” barges were picked up by a clamshell bucket and placed in precise areas around the drilled shafts.

Once the quarry stone had been placed for both islands, 3 shiploads of 160 to 300 lbs pieces of armor stone are placed on top of the quarry stone. After the medium stone has been placed, approximately 2 shiploads of the large 2400 to 4000 lbs armor stones were placed around the tower footings where waves strike the towers.

Picture of Rock Island