Hundreds of artifacts, including Confederate ammunition dumped by Union soldiers in the Civil War, were recovered during a cleanup of the Congaree River in Columbia, South Carolina.

The multiyear, $20 million project was declared complete by Dominion Energy Monday. A predecessor had operated an unclean gas plant around a century ago, the company said, and had in the process dumped a material akin to coal tar into the river, trapping artifacts in the sediment.

The artifacts ranged the gamut of the state capital’s history, from indigenous peoples to the Civil War.

Cannonballs and other ordnance in the river dated to the Feb. 17-18, 1865, capture of Columbia by Union Gen. William Tecumseh Sherman as part of his Carolinas campaign to close out the war. The munition, left behind by fleeing Confederate troops, was dumped in the river by the Union to further demoralize the secessionists.

The Civil War-related finds also included a sword blade and even a preserved wooden wagon wheel believed to have come from a supply wagon that exploded.

“It’s an interesting story to tell. It’s a good one — that we were able to take a real piece of it rather than just the written record showing this is what happened,” Sean Norris, the archaeology program manager with environmental consulting firm TRC, told The Associated Press.

The recovered artifacts will now head to the South Carolina State Museum and the South Carolina Confederate Relic Room and War Museum, both located in Columbia. They will not see public display for a couple of years as they undergo testing.

One piece of the uncovered ordnance was “demilitarized” at Shaw Air Force Base, AP said.

“I think it’s very important. I think we need to preserve our history because we can learn so much from it. We’re in the middle of a restoration of battlefields all across South Carolina,” South Carolina Gov. Henry McMaster, a Republican, said, WLTX-TV reported. 

In addition to the artifacts, other debris, including trash, scrap metal and tires, was removed from the Congaree River. Altogether, 2.5 tons of debris were taken out, in addition to the tar-like pollutant and river sediment.

The project ended up finishing ahead of schedule with the help of Mother Nature.

“The river levels over the last two years were very cooperative. It helped our crews finish work in the river a year earlier than originally scheduled,” Tom Effinger, the environmental director at Dominion Energy, said in the company’s announcement.

• Brad Matthews can be reached at bmatthews@washingtontimes.com.