OLD TOWN — The ND Paper mill in Old Town spilled more than 30,000 gallons of pulping chemicals into the Penobscot River earlier this month, officials said.

The mill suspended production after discovering that chemicals were spilling into the river through a ruptured underground sewer line and a failed floor drain on Oct. 7, the Bangor Daily News reported.

The mill reported the leak to the Department of Environmental Protection, which helped with the spill cleanup and repairs to the infrastructure the following day.

Chemicals spilled periodically over a six-day span, said Brian Kavanah, director of the state agency’s bureau of water quality.

The mill restarted production Oct. 17, according to Brian Boland, vice president of government affairs and corporate initiatives at ND Paper, which also operates the paper mill in Rumford.

“Our priority is the safe operation of our facilities, in full compliance with all applicable rules and regulations,” he said.