2,000 litres of hydrochloric acid escaped from a vat at the Denman plant before being contained by staff. Nobody was injured in the incident.
WorkCover has issued three improvement notices to Muswellbrook Shire Council in relation to emergency management procedures, plant maintenance and work procedures.
The council says it has some concerns about the cause of the spill.
Muswellbrook Mayor Martin Rush says staff have co-operated fully with Workcover investigators.
“But there are some things that are of concern,” he said.
“Standard work method statements didn’t appear to be in place.
“It would appear that a maintenance regime would have assured that this didn’t occur.”