Nearly 60 years after industrial mercury pollution began contaminating the Penobscot River, a project to remediate it has taken a step forward.
One of the legal entities established to run the multimillion dollar cleanup, Penobscot Estuary Mercury Remediation Trust, filed state and federal permit applications last week for a pilot project to cap East Cove 3 in Orrington with several inches of sand.
If approved, the results of that multiyear pilot would help determine how the trust remediates at least nine tons of mercury that have remained in the river and its estuary since the late 1960s.
That contamination has limited human uses in the river and affected animal health downstream of Orrington, as well as in surrounding areas including North Bucksport, the channel east of Verona Island, Mendall Marsh in Frankfort and Prospect, the Orland River and further upstream to Indian Island.
Mercury makes its way up the food chain and acts as a neurological poison in fish, wildlife and people. The river’s flats have been closed to fishing for a decade because of mercury levels, and eating advisories have been in place even longer.
The pilot project would place four to six inches of sand on about 6.3 acres of Orrington Reach in East Cove 3, next to the town’s Picnic Park. It aims to show this method is effective in the river, as it has been elsewhere, according to project documents. The cap is expected to speed up the river’s natural sediment deposit process and reduce current mercury exposure.
Work would take two to four months and be completed by barge in the water, according to proposal documents.
Applications for the work were filed last week with the Maine Department of Environmental Protection and the U.S. Army Corps of Engineers.
Researchers plan to check for erosion, stability, mercury levels and effects on the nearby marsh and shoreline for at least two years after construction. The pilot also aims to answer the question raised by some members of the public about the ability of the cap to withstand winter ice floes.
“[It’s] a demonstration so we can answer our questions and everyone else’s,” Lauri Gorton, program manager for the remediation trust, said.
Many residents have been supportive throughout the town hall meetings and informational sessions the trust has held on the project, according to Gorton.
Public comment on the permit will be open through the processing period and the department may hold a public hearing if enough people request it. Maine DEP currently lists application processing times of 120 to 150 days.
If permits are approved, construction would start in the fall months to avoid disrupting spring spawning, according to Gorton. That could happen this year or next, depending on the approval process.
If the pilot project is successful, draft plans call for eventually capping about 130 acres of intertidal flats in Orrington Reach, dredging sediments that move with the tides and finding a plan for contaminated sediment in the Orland River and the east channel around Verona Island.
For the final cleanup, the group managing the trusts will need permits and approvals from neighboring landowners, its president told the BDN in 2024.
Mallinkrodt and the state continue to monitor the roughly 12-acre factory site and work on remediation of its contaminated land. It has removed more than 265,000 tons of contaminated soil across eight sites.
The cleanup of mercury contamination in the river could become a model for addressing industrial contamination in other Maine waterways. It’s also unique because it’s happening through the terms of a consent decree that took almost 22 years to move through the court system.
The mercury was discharged in the river starting in 1967 under previous owners of the Holtra-Chem Manufacturing Plant, which produced caustic soda, chlorine and other chemicals for the state’s paper and pulp industries. Occasional spills were reported into the late 1990s. That plant closed in 2000, and the same year, the Maine People’s Alliance and the Natural Resources Defense Council sued its owners.
In the eventual consent decree, Mallinckrodt USA LLC, the last company with an ownership stake in the plant that still exists, agreed to pay between $187 million and $267 million for cleanup.
The decree created two independent trusts, one charged with leading the expansive remediation process and the other to focus on environmental projects. The remediation plans result from an engineering study and scientific research outlined in that decree.
The overall remediation is expected to take years.
Correction: A previous version of this story misstated the name of Penobscot Estuary Mercury Remediation Trust. It also misspelled Lauri Gorton’s first name and misstated her role.