A small spill of muriatic acid along U.S. 441 in the Great Smoky Mountains National Park initiated a rapid clean-up response from park personnel last Thursday, blocking all traffic through the park between Cherokee and Gatlinburg for 5 hours in the process.

The spill happened just past the Oconaluftee Visitor Center at the park’s main North Carolina entrance.

A gallon plastic container of muriatic acid fell off a truck and was hit and ruptured by another vehicle causing the material to spew out onto the south-bound lanes, according to a park press release. The spill created a fog of vapors that were irritating to those breathing the fumes.

Muriatic acid is used in concrete cleaning and finishing so Rangers suspect that the container may have fallen from a contractor vehicle doing work inside the Park.

The liquid on the pavement was cleaned up with the assistance of the Cherokee Fire Department using absorbent pads, but part of the material had already run off onto the adjacent grassy shoulder.

Park managers contracted with a firm in Cherokee that is certified to clean up hazardous materials to dig up contaminated soil from the roadside and to collect it in drums for disposal. Personnel handling the materials donned protective suits and respirators to operate heavy equipment and hand tools to collect the soil. No acid is believed to have escaped into the Oconaluftee River, which lies across U.S. 441 from the spill area.

There were no injuries reported, but three Park employees who had been exposed were sent to be checked out.