The Winthrop Landfill Superfund site on Tuesday. Joe Phelan/Kennebec Journal

WINTHROP — Town officials have agreed to amend a consent decree with the U.S. Environmental Protection Agency regarding the town’s superfund landfill and arsenic accumulating in the sediment at Hoyt Brook.

Superfund sites were designated under the Comprehensive Environmental Response, Compensation, and Liability Act of 1980 and are defined as polluted areas in the country with hazardous material contaminations that require a long-term clean-up response. 

The Winthrop landfill, which consists of two contiguous parcels of 11 acres, 9.5 of which are along the shore of Annabessacook Lake, was deemed a superfund site in 1985. According to the Nov. 22, 1985, decision, “it is estimated that more than three million gallons of chemical wastes, mostly complex organic compounds including resins, plasticizers, solvents, and other process chemicals were disposed at the site.”

Since the decree was established, the EPA has monitored and addressed treatment of the landfill. In 2015, officials installed a barrier on the bank of the brook with United Technologies Corp. (now known as Raytheon Technologies Corp.) as part of a pilot study. EPA officials recently found that groundwater discharging into Hoyt Brook was depositing arsenic into the brook’s sediment.

The new amendments include continuing to use the sediment cover system installed during the pilot study, surface water and sediment monitoring, inspections and maintenance of the cover system. A new amendment also includes recording an environmental covenant on the property where the cover system is located, granting access for construction and repair work and preventing any unauthorized excavation or other disturbance to the cover system.

Rebecca Hewett, project manager for the Maine Department of Environmental Protection’s national priority list of superfund sites, spoke of the amendments during a Monday night public hearing hosted by the Winthrop Town Council. Hewett said that those involved with the original consent decree likely did not anticipate the accumulation of arsenic into the sediment.


“We were treating the groundwater for a long time, but they found that even if you treated the groundwater leaving the landfill, the ground would sort of pick up arsenic along the path to Hoyt Brook, and so there was no amount of treatment we could do to the groundwater that would solve the issue with arsenic accumulating in the sediment,” said Sarah Meeks, enforcement counsel for the EPA. “So we had to address the sediment directly with a new add-on remedy.”

Aside from arsenic, which is an inorganic contaminant, Hewett said the main contaminates for the landfill were volatile organic compounds, although these are now at acceptable levels.

“We will have some detection of certain (volatile organic compounds) in the southern flow path, but they’re below standards,” said Hewett. “So we’re meeting the cleanup criteria — all but arsenic.”

A Winthrop resident who owns land adjacent to the landfill asked about the eventual delisting of the site as a superfund, and how that will impact the area in terms of oversight and work being accomplished. Meeks said the deletion of the Winthrop landfill as a superfund is coming in the future, but the amendment being presented was solely related to amending the decree to address the arsenic deposits.

Almerinda Silva, environmental project manager and engineer at the EPA, said the public will be involved every step of the way during the deletion process.

“We’re going to put out a fact sheet. And we’re going to have a meeting, which will probably end up being virtual, to be able to answer questions that people may have,” Silva said.


The Winthrop Landfill Superfund site Tuesday. Joe Phelan/Kennebec Journal

She said that while the wording may sound like the site is being “deleted,” the EPA, Raytheon and the town will continue to perform long-term monitoring.

Hewett and Silva said deletion means that the EPA can tell lawmakers there are no outstanding issues or tasks in the consent decree that need to be addressed.

“But we don’t go away,” Silva said, “we continue to keep an eye on the site to make sure nothing unexpected happens. This is why we do five-year reviews, to make sure that it continues to be safe.”

Sandy Small-Hughes, chairperson of the Cobbossee Watershed District, asked if officials have looked at the budgetary aspect of monitoring the site.

Town Council Chairperson Sarah Fuller said that Raytheon handles the majority of fiscal responsibilities, and the town does not have to budget for monitoring personnel or costs associated with that work.

Hewett added that the town and Raytheon’s agreement works in such a way that if Raytheon went bankrupt, the town would be responsible for picking up where the work left off.

“However, Raytheon seems to be a fairly healthy company and you guys have been good partners since coming on board, so hopefully that will continue,” said Fuller.

All five present councilors voted Monday night in favor of accepting the amendment. Councilors Priscilla Jenkins and Rita Moran were absent.

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