July 29--An engineering firm tasked with figuring out the most cost-effective ways to clean up the estimated nine tons of mercury from the state's largest river has come up with six options -- including one that calls for doing nothing.
The now defunct HoltraChem Manufacturing Co. made chlorine, pesticides and papermaking chemicals at the 235-acre Penobscot River property in Orrington over four decades, and Amec Foster Wheeler, a global engineering firm with an office in Portland, is researching ways to get rid of contaminants the company dumped into the waterway.
"We're looking at all the remediation options ... that may be feasible in the river," Mary Kelley, of Amec Foster Wheeler, said Wednesday.
The range of river cleanup options include digging it up; putting a barrier over the pollution; trapping sediments using a berm; adding a substance that clumps particles; digging the mercury out and capping the area with an underwater containment cell; as well as replacing the contaminated soil with clean sediment, or just leaving the mercury as is, according to Amec Foster Wheeler's website created to keep residents informed of the progress.
Leaving the area to recover naturally is one option, but a 2015 report from a panel of scientists assigned to investigate it, estimated it would take "about 33 years for [mercury] concentrations to be low enough in the main stem of the river to not cause problem levels in biota." It would take even longer -- 60 years -- in Mendall Marsh, where there is a pool of mercury.
A federal judge next year will decide which method the company responsible will use. The overall cleanup cost is estimated at $130 million.
"Ultimately, the court will make a decision ... whether the benefits of any one or more alternatives proposed by Amec outweigh those of other options available," said Mark Robinson, spokesman for Mallinckrodt Inc., the only former operator of the plant that still exists, and is paying for the cleanup.
While Amec Foster Wheeler completes its study and creates river cleanup recommendations, Camp, Dresser & McKee-Smith, an environmental firm hired to do the site cleanup, this week continued to remove contaminated soils from the property. It worked on the edge of Southern Cove, an inlet on the property, and have scheduled dredging work in the river in the near future to remove even more contaminants from the cove.
Maine People's Alliance, along with the National Resource Defense Council, sued HoltraChem and Mallinckrodt Inc. in 2000 to force the cleanup under the Resource Conservation and Recovery Act.
"The public's role at this point is to demand the full cleanup of the river," said Mike Tipping, MPA spokesman. "And that Mallinckrodt pay for what they did here. [Amec Foster Wheeler's] feat is to figure out the technical means to do it."
One option is to let nature take its course, but Tipping said he believes the study will conclude that additional cleanup steps are needed.
"This is an unprecedented level of mercury," he said, referring to a 2013 Department of Environmental Protection scientific study that says six to 12 tons of mercury was discharged from HoltraChem into the Penobscot between 1967 and the early 1970s, and smaller amounts were released afterward. About 9 tons remain, the report found.
After the study was released, the Maine Department of Marine Resources in 2014 banned fishing for lobsters and crabs from Orrington down to Fort Point Lighthouse on Cape Jellison in Stockton Springs. In 2016, the ban was extended further south, down to Squaw Point and Perkins Point, which is several miles south of Verona Island.
Mercury remains in plants and animals in the river, according to a 2016 environmental monitoring report released by Amec Foster Wheeler on May 31.
HoltraChem, which was owned by various companies over the years, produced chemicals and pesticides from the mid-1960s to 2000, when it closed in bankruptcy.
Mallinckrodt, a subsidiary of global health care products giant Covidien, owned and operated the plant from 1967 to 1982 and is the sole former owner still in existence. The company has already paid millions to remove contaminated buildings and equipment, and tons of mercury from the site.
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