BUSINESSES on Winwick Quay industrial estate were evacuated after a chemical spill at Cameron Court on Tuesday at 1.55pm.
Twenty litres of nitric acid spilled into a contained drainage system and reacted with steel.
All fluid was contained on site and there were no casualties or injuries reported.
A Cheshire Fire spokesman said: “The premises were ventilated and the quality of air was sampled by an on-site chemist.
“Adjoining properties were evacuated as a precaution.
“The buildings were declared clear and staff were allowed to re-enter the buildings.”