DHEC reviews new plan to seal coal tar in Congaree River

Cofferdam plan not favored

Coal tar remediation on the Congaree River has officially moved to a plan to seal and cap the spill.

Tar site after the 2015 flood and a portion of the Columbia Canal wall collapse. Sandbags are where clean-up is planned.

The S.C. Department of Health and Environmental Control (DHEC) held a public meeting, Monday, to discuss plans to mitigate the hardened coal tar sediment on the bottom of the Congaree River. The tar accumulation is on the Columbia side, between the Gervais and Blossom Street bridges.

At one time, SCE&G, the company cleaning the 50-100-year-old spill, planned to build a cofferdam to “dry” clean the river bed and remove the tar.

But DHEC’s Ken Taylor said Monday night, the Army Corps of Engineers came out against the $18 million plan to build a cofferdam. The Army Corps must approve any plan regarding the tar clean up. The risk of causing erosion and flooding was the reason the Army Corps opposed a cofferdam, Taylor said.

He also said cleaning the tar without damming off the river could expose the cleaning crew to the danger from un-exploded munitions, that could be buried in the river from when the Union Army of Gen. William Sherman dumped them in the river in 1865.

DHEC and SCE&G have proposed a $7-to-8 million plan to the Army Corps to seal the hardened coal tar with a fabric cover and then place a stone topping on that. The cap would isolate the tar and create a permanent barrier. Natural silt would then cover the installed cap, according to the plan.

“We are waiting to hear from the army Corps of Engineers,” Taylor said. The site would be monitored to make sure the tar is contained under the barrier.

He also said SCE&G preferred the more expensive plan to totally remove the tar, but could not incorporate it because of the Army Corps of Engineers.

Ken Taylor of DHEC shows a shovel of coal tar photo.

After Taylor explained the process, the floor was opened for questions.

Some complained about the fix.

“You need to go back to the drawing board,” said Ann Timberlake.

She said she is not satisfied with the cap and seal approach and planners need to” think more creatively.”

Another asked if there would be a chain link fence over the three-acre area. Taylor said there would not be.

Joe Azar alluded to an oil eating bacteria that was used to help clean an oil spill in the Gulf of Mexico.

Taylor said that would not be effective in the Congaree River clean up.

Monday’s meeting was held at the Edventure Children’s Museum.

 

Lots of questions were asked.

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