Cofferdams on the Congaree River are beginning to take shape

The effort to build two cofferdams on the Congaree River is taking shape. If you ride across the Gervais Street Bridge, you can see it.

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Dominion Energy has contracted a company to build the cofferdams so that coal tar from long-closed oil plant can be cleaned from the river bottom.

The work site is on the Columbia side of the river just yards from the Gervais Street Bridge. The first cofferdam is being built across from the West Columbia Riverwalk Amphitheater.

Currently, a rock wall, jutting out into the river is visible. It will eventually have three sides to it. Construction has also begun on the second cofferdam. It is smaller and it’s closer to the Blossom Street Bridge in Cayce.

The clean-up is being conducted on a portion of the river that could contain Confederate Army unexploded ordinances disposed of in February 1865, during The Civil War. It’s possible that unexploded ordinances are buried in the sediment.

Completion of the two dams is expected by October, said Greg Cassidy in May. He’s a project manager for the State Voluntary Clean-Up Program that is connected to the SC Department of Health and Environmental Control. Removal of the tar would likely begin in the spring of 2023 because of the unpredictable level of the river in the months of November, December of January, said Cassidy.

Removing the coal tar will allow for more access to the river, and the opportunity for increased residential development, between the Gervais and Blossom Street bridges.