NP Paper mill with smokestacks along the river
ND Paper mill in Old Town, pictured in November 2020. Credit: Linda Coan O'Kresik / BDN

ND Paper will have to pay Old Town $101,400 to resolve violations tied to an October 2020 spill when more than 30,000 gallons of pulping chemicals leaked into the Penobscot River, according to a pending agreement.

The agreement is between ND Paper and the Maine Department of Environmental Protection, and it describes violations and steps the pulp mill has taken to correct them.

It also requires the company to pay a penalty to Old Town so the city can complete a $450,000 environmental project that would remove a corrugated steel pipe culvert under College Avenue Extension and replace it with a larger, higher quality concrete culvert. The hope is to restore the stream and provide better access to fish and other organisms from the Stillwater and Penobscot Rivers.

The agreement is the first time new details of the Oct. 7, 2020, spill and its cause have been made public. On that day, ND Paper discovered elevated pH levels at its wastewater treatment plant and concluded the most likely source was the sewer system from the mill’s recovery boiler area, spokesperson Jay Capron said. More specifically, the agreement details a ruptured below-ground sewer line that seeped into the river.

“Sustainability and environmental compliance are a key part of ND Paper’s 100-year vision and we highly value energy conservation and environmental protection,” Capron said.

ND Paper investigated the leak and estimated 30,720 gallons of 50 percent sodium hydroxide — also called caustic soda, which can harm those who come into contact with it — were discharged to a failed floor drain in one of the mill’s buildings. This happened daily between Sept. 29, 2020, and Oct. 7, 2020, and intermittently over 56 days throughout 2021, according to the agreement.

The solution then traveled through the ground and groundwater at the mill, eventually releasing from several unlicensed points into the forebay area of the Penobscot River.

ND Paper suspended operations on the day of the spill and notified the Maine DEP and the United States Nuclear Regulatory Commission on Oct. 8, 2020. Operations resumed Oct. 27 of that year.

Workers discovered another spill involving the same solution on June 29, 2022, which they tied to the failed floor drain that was one of the main reasons for the 2020 spill. The company estimated that 1,076 gallons leaked into the ground below the building over 30 days.

ND Paper has worked to correct its violations tied to the 2020 incident, Capron said, though he didn’t provide details.

The agreement lists installation of new shut-off valves in the mill’s caustic line and alarms for better detection of caustic liquid flows, among other actions. Equipment in the building with the failed floor drain will now have regular monitoring.

The Maine DEP issued a notice of violation to ND Paper on March 19, 2021, not including the leak and discharge that the company found in June 2022.

In July 2021, ND Paper submitted a consultant engineer’s report to the Maine DEP, which described the event, response, status and conclusions. The report did not recommend any further remedial measures, according to the agreement.

ND Paper replaced about 400 feet of stainless steel piping, equipping the piping with electric heat tape and repaired failed floor drains in response to the June 2022 spill, according to the agreement.

The Maine DEP is accepting public input on the agreement until July 28.