Dominion Energy Announces Early Completion of Congaree River Project

Gov. McMaster, City of Columbia Recognize Multiyear Environmental Achievement

CAYCE, S.C. (Nov. 13, 2023) – Dominion Energy on Monday marked the completion of a complex, multiyear project to remove tar-like material from the Congaree River in downtown Columbia.

Gov. Henry McMaster and Columbia Mayor Daniel Rickenmann joined other dignitaries to recognize the $20 million project that finished ahead of schedule.

“This was a highly unique project that had never been attempted anywhere in the United States in a river at this scale,” Dominion Energy South Carolina President Keller Kissam said. “Its successful completion is a testament to the excellent coordination and relationships among our employees, regulators, contractors and stakeholders who helped guide the work. There were many who doubted that it could be done, but I’m here today to say proudly that not only did our exceptionally talented and dedicated team do it, they did it in a manner that sets the example for others to follow.”

Crews removed tar-like material in the Congaree riverbed that was first discovered in June 2010. Dominion Energy committed to remediating the material after lab testing showed it was consistent with coal tar created at a manufactured gas plant located near what is now the South Carolina State Museum and operated by predecessor companies approximately a century ago. The plant produced gas from coal, oil and other feedstocks, which was used for lighting, cooking and heating Columbia homes and businesses. 

Starting in June 2022, crews installed cofferdams and dewatering pumps at two locations in the river so they could work on a dry riverbed. They then removed more than 35,000 tons of sediment for disposal in an approved landfill. Dominion Energy also worked with archaeologists to recover hundreds of historical artifacts from the river sediment, including cannonballs and other ordnance that have been in the river bottom since the Civil War.

"Protecting our environment and natural resources is a top priority for Team South Carolina," said Governor Henry McMaster. "Healthy waterways benefit us all and ultimately lead to a happier and healthier state. I thank Dominion Energy and all of those involved for getting this project done ahead of schedule."

The modified removal agreement reached with the South Carolina Department of Health and Environmental Control, Army Corps of Engineers and other stakeholders authorized work in the river from May 1 until Oct. 31 of each year.

“The river levels over the last two years were very cooperative,” Dominion Energy Director, Environmental Tom Effinger said. “It helped our crews finish work in the river a year earlier than originally scheduled. I’m very proud of the way our contractors found innovative ways to overcome the numerous challenges to make this happen for the good of our community.”

In addition to the sediment, crews also removed more than 2.5 tons of debris from the river, including tires, scrap metal and other trash.

Video: Dominion Energy Completes Work on Congaree River (Please credit Dominion Energy

About Dominion Energy
About 7 million customers in 15 states energize their homes and businesses with electricity or natural gas from Dominion Energy (NYSE: D), headquartered in Richmond, Va. The company is committed to providing reliable, affordable, and increasingly clean energy every day and to achieving Net Zero emissions by 2050. Please visit to learn more.