Mercury in the Penobscot River and Estuary
Mercury is a common pollutant in Maine and more general information is available on the State’s website. The mercury impacts to the Penobscot River that are the focus of the Phase III Study have been determined through Court proceedings to be result of wastewater discharges from the former HoltraChem mercury-cell chlori-alkali plant.
The chlor-alkali plant, located on a 240-acre property in Orrington, Maine, manufactured chlorine and sodium hydroxide. Various companies that operated the plant over its lifetime released mercury-impacted brine sludge into its sewer system, and in the early years of operation through the facility’s outfall directly into the Penobscot River, or placed mercury-impacted brine sludge into waste disposal ponds that leached into the River. The majority of these releases occurred from December 1967 through June 1970, and declined, but continued to some extent, after 1970.
During the time of peak releases, the chlor-alkali plant was owned and operated by International Minerals and Chemical Corporation (IMC), a corporate predecessor to Mallinckrodt US LLC (Mallinckrodt). More recently, from 1994 through 2000, the plant was owned and operated by HoltraChem Manufacturing Company, LLC (HoltraChem). As a result, it is often referred to as the HoltraChem plant. However, HoltraChem ceased operations in 2000 and dissolved in 2001, leaving Mallinckrodt solely responsible for addressing the environmental contamination from the plant.
Mercury contamination at the HoltraChem site is the focus of a mandated remediation project being conducted by Mallinckrodt and overseen by the State of Maine. More information is available through the DEP’s website.
To address mercury contamination in the Penobscot River, the Maine People’s Alliance and Natural Resources Defense Council (collectively the Plaintiffs) filed a lawsuit against HoltraChem and Mallinckrodt (collectively the Defendants) on April 10, 2000, alleging violation of certain provisions of the Resource Conservation and Recovery Act (RCRA). The Plaintiffs requested that the Defendants undertake an independent scientific study of the mercury contamination downstream of the HoltraChem site, and develop and implement a remediation plan. Following findings by the United States District Court – District of Maine (the Court) that Mallinckrodt was liable under RCRA, the Court ordered on November 25, 2003 that Mallinckrodt fund a study of mercury in the Penobscot River (Implementing Order).
Mallinckrodt has funded that study, which resulted in both a Phase I Study and Phase II Study. Both studies have been supervised by the Special Master appointed by the Court. Mallinckrodt is funding the current Phase III Engineering Study.