No injuries were reported as a result of the accident at the Defense Waste Processing Facility, where high-level radioactive waste is encased in glass, and officials said it did not warrant the notification of people living near the site.
However, authorities barricaded access points into the site and cut off traffic on South Carolina Highway 125 from 10:39 a.m., when the accident happened, until 2:17 p.m.
Employees were told to remain indoors.
Bobby James, a member of the emergency response team and a Washington Savannah River Co. employee, said the chemical was contained in a concrete holding area beneath the tank at the facility.
The chemical is a colorless, corrosive liquid that can cause severe burns on the skin and is harmful to the lungs and eyes.
Will Callicott, a company spokesman, said the formic acid is used to dissolve sludge waste from the high-level waste tanks.
Bill Poulson, Washington Savannah River Co.'s executive vice president for liquid waste, said special teams with air monitoring equipment determined that the chemical spill did not pose any danger to anyone in the vicinity of the facility.
"They came at it from both upwind, downwind and around it, and they're all showing zero detectable levels of any of this vapor in the air," Mr. Poulson said.
Authorities didn't know when the cause of the spill would be determined, but normal operations were expected to resume Monday, Mr. Poulson said.
"We will critique the event to see how the leak occurred and implement any fixes," he said.
Officials became aware of the incident when an operator, whose name has not been revealed, was checking the Defense Waste Processing Facility area and noticed that the formic acid was draining from a holding tank into a concrete holding area below. The employee closed a manual valve to stop the leak.
"An operator making rounds was, I guess I'll say, to be congratulated - he was inquisitive," Mr. Poulson said.
He said a site emergency was declared and all employees were directed to remain indoors as a precaution as the facility's emergency operations center and technical support center were activated.
South Carolina and Georgia officials were notified, and the site's perimeter barricades were moved into place as law enforcement closed Highway 125 through the site, he said.
"Being good neighbors is a part of this whole operation," Mr. Poulson said.
James R. Giusti, a spokesman in the office of external affairs for the Department of Energy, said department officials in Washington, D.C., also were contacted.
Mr. Poulson said employees wearing protective suits should be able to finish pumping the chemicals back into a storage tank today.
Reach Nathan Dickinson at (706) 828-3904 or firstname.lastname@example.org.
ABOUT FORMIC ACID
Formic acid is a colorless, volatile organic acid that occurs naturally in ants and also is formed as a byproduct in the oxidation of turpentine. Its commercial source is sodium formate, and it is used in leather manufacture to control pH levels, and in acid dyeing of some leathers. It's also used in some household limescale cleansers.
Source: Stanford University