DEVENS – After nearly two years of collecting samples and gathering data, contractors for the U.S. Army Corps of Engineers announced progress in filtering out chemical compounds in local water supplies.
Last Thursday’s meeting of the Devens Restoration Advisory Board featured another update of the engineers’ investigation into traces of per- and polyfluoroalkyl substances, or PFAS, detected in area wells.
The Corps has been sampling water wells surrounding the former Fort Devens since 2018, two years after the Massachusetts Department of Environmental Protection required towns with those wells to test for PFAS in response to reports about contamination.
At the board’s last meeting in October, contractors detailed three areas surrounding the former base in Ayer, Shirley and Harvard that had sources of groundwater contaminated with the chemical compounds.
The exact cause of the contamination has yet to be confirmed by the Corps, though Washington, D.C.-based nonprofit The Environmental Working Group reported last month that fire-fighting foam containing PFAS was used at the base.
The group claimed bits of the foam seeped into nearby water wells and groundwater sources, leading to traces of PFAS in local drinking water supplies.
Jim Ropp, project manager for Koman Government Solutions, also noted that the highest concentrations of PFAS in groundwater in Devens were located at the Moore Army Airfield, where a firefighter training area was found at the end of one of the runways. Firefighters would set up a burn area and use the foam to put out fires.
“Back when this was done, there was no concern for the foam,” he said.
Both the state DEP and the U.S. Environmental Protection Agency advise that the maximum amount of the chemical compounds to have in any form of drinking water is 70 parts per trillion. However, the DEP proposed last month to have the maximum contaminant level for PFAS in drinking water lowered to 20 ppt. The DEP is hosting five public hearings throughout the year to garner public opinion on the proposed level
That proposed lowered measurement is what the Corps used as an additional measuring stick to show off the lowered levels of chemical compounds in the local water. Ropp said about 100 private water wells in Harvard were sampled for PFAS and other chemical compounds, with none of them having levels going over the EPA health advisory level.
Eight of the sampled wells in Harvard had traces exceeding the proposed 20 ppt level, including wells on Ayer Road, Blanchard Road, and Lancaster County Road. Nearly 40 of the sampled wells had levels of chemical compounds under the proposed 20 ppt, including wells on Myrick Lane, Old Mill Road and Depot Road.
Ropp said that the two areas that have compounds traces above 20 ppt are north of Ayer Road and near Blanchard Road. He added that more sampling of wells in Ayer and Shirley, specifically wells north of the closed airfield, have been proposed.
“Multiple sources could be possible,” Ropp said. “We’ve now taken the next step into the remedial investigation, which is the in-depth sampling: lots of groundwater and lots of soil. We’ve been able to target a dozen or so areas of concern.”
Ropp then moved on to samples taken at five wells in Ayer in November. Ropp said the “area of focus” was three wells located at Grove Pond, where a water treatment plant is currently being built. The plant is expected to be completed by this June and will treat up to two million gallons of water per day. When the water of the three wells were mixed together for public use, 16.7 ppt of chemical compounds were detected, making it well under both the established and proposed health advisory levels of compounds.
The other two wells located at Spectacle Pond, where another water treatment plant is being designed, had a combined chemical compound level of 27.2 ppt, well under the established levels but slightly higher than the proposed compound level.
“The town is doing some bench scale testing for a possible treatment option and are working with the state,” Ropp said.
The Corps plans to continue its remedial investigation of areas in Ayer, Shirley and Harvard. Sampling of municipal water supply wells and more private water wells north of the old airfield are set to take place in February and March.
Katie Thomas, a Koman project manager, said that more vertical profiles and monitoring wells are planned to be installed through the areas of concern this year. There are also plans to collect samples of surface water and sediment samples for further investigation of compound traces in forms of water aside from drinking water. She also announced a specific investigation of Cold Spring Brook, located southeast of Devens.
“We have a number of sites close to the brook based on the groundwater data we’ve collected so far,” Thomas said. “It looks like PFAS is coming to the edge of the brook, so we’re planning more surface water sediment sampling.”
The Corps also has its Community Involvement Plan, which describes the Army’s outreach program to local residents discussing further environmental investigations at the former base. Residents can view the plan at ftdevens.org and submit comments about the plan until Feb. 3, when the Corps will take in the data to create a final draft plan to be presented in early May. The final set plan is expected to be established by mid-June.
Attendees still showed concern not only for local drinking water, but how contaminated water could impact surrounding nature. Groton resident Marion Stoddart, who co-founded the Nashua River Watershed Association, said she was concerned about traces of PFAS entering the Nashua River and emphasized the need to focus on natural water quality.
Laurie Nehring, president of the People of Ayer Concerned about the Environment, shared Stoddart’s concerns.
“The longer we wait and study these aquifers and the contamination issues, the more they spread into the river systems and other people’s drinking water,” she said. “I would be concerned about trying to address it while its as compact as it can be, because it’s only going to get worse.”