State and federal environmental agencies contend that the U.S. Air Force isn’t doing enough to find and stop the source of PFAS chemicals that may be contaminating Bedford’s suspended indigenous water supply.
The disagreement was acknowledged at last week’s annual meeting of the Restoration Advisory Board at Town Center. The board reports on remediation progress and plans involving areas at Hanscom Field contaminated by hazardous waste.
PFAS is an abbreviation for per- and polyfluoroalkyl substances; they have been identified as possible human carcinogens. Matthew Greenberg, the Air Force’s remedial project manager, told the board meeting that these “emerging contaminants” are found in many commercial and industrial products, including the foam used to suppress burning liquids such as jet fuel.
In 2019, Bedford officials suspended use of the Shawsheen Road wellfields after levels of PFAS were detected approaching maximum state standards for safe consumption. Those wells are adjacent to the Shawsheen River; Hanscom Field is a couple of miles upstream in the Shawsheen watershed.
In a Nov. 10 letter to Greenberg, an official of the state Department of Environmental Protection’s Bureau of Waste Site Cleanup cited the most recent five-year review, issued two months ago.
“There is no groundwater/drinking water exposure pathway associated with Hanscom,” the letter said.
But that position “improperly minimizes the potential risks posed by PFAS impacts from Hanscom,” wrote Diane Baxter, director of the bureau’s Division of Federal Grants Programs. “The wellfields have not been permanently abandoned. The town of Bedford reserves the right to use those wells in the future.”
The concerns were also summarized at the advisory board meeting by Randi Augustine, a DEP environmental analyst, who was speaking remotely. “There are several downstream drinking water sources that have reported elevated levels at their intake point – these were not considered exposure pathways in the five-year review.”
Several weeks ago, similar concerns were raised by Bryan Olson, director of the federal Environmental Protection Agency’s Superfund and Emergency Management Division. The EPA oversees Superfund remediation efforts.
That letter rejected the Air Force plan to separate PFAS source investigation from the ongoing site cleanup.
“Since PFAS is present in media with other chemical contaminants, cumulative risk and treatment options must be assessed holistically,” he wrote.
Identification and remediation of contaminated sites at Hanscom Field, including grassy areas around the runway and landfill sites, have been ongoing for decades. They fall under the federal Comprehensive Environmental Response, Compensation and Liability Act, also known as the Superfund.
There are three Superfund “operable units” for cleanup at the airfield. One of them, the source of PFAS as well as other contaminants, comprises areas near the runways where many years ago Air Force personnel set and extinguished fuel fires for firefighters’ practice and disposed of paint and jet fuel.
The Air Force turned the runways over to the Massachusetts Port Authority almost 50 years ago but is responsible for the contamination that took place under its ownership.
The pollutants’ presence continues to be detected in groundwater, and a treatment plant has been operating at Hanscom since 1991. The plant was taken offline in 2021 to repair a boiler. Early this year the EPA and DEP requested that the facility remain idle because PFAS chemicals were detected in the effluent.
Greenberg acknowledged at the meeting in Bedford that the treatment “works great for chlorinated organic compounds, but was not designed to treat PFAS,” that “wasn’t a contaminant concern until five to seven years ago.”
Indeed, in answer to a question from Bedford resident Jennifer Boles, he acknowledged that the treatment plant may have been exacerbating PFAS content by continuing to pump. “We have been extracting groundwater that contained PFAS and discharging to an effluent point that does connect to a wetland and eventually to the Shawsheen River.”
Baxter, of the Massachusetts DEP, noted that her agency’s surface water studies several months ago resulted in evidence that the PFAS in the Shawsheen River, as well as its tributary Elm Brook, emanated from Hanscom.
“The studies identified the presence of PFAS with a fingerprint indicative of legacy PFOS-based AFFF, which historically have been used in firefighting operations,” she wrote. “The highest concentrations were detected near the headwaters of the Shawsheen within Hanscom, with a pattern of decreasing concentrations with distance from Hanscom.”
Baxter’s letter also pointed out that “the Town of Burlington’s Mill Pond Reservoir draws its drinking water supply directly from an intake on the Shawsheen River,” and PFAS contamination was discovered in that supply in April 2021. That remains an active water supply, she added.
Greenberg said the “expanded site inspection” for PFAS is complete and development of a remedial investigation work plan is underway. Baxter’s letter said the Air Force hopes to determine if a restored groundwater treatment plant “can be retrofitted to address the PFAS contamination in groundwater extracted.”
The EPA directed that by the end of September 2024, “the Air Force must complete its groundwater treatment plant treatability study for PFAS and implement any resultant recommendations necessary to ensure compliance” with effluent standards.
And a year later, “the Air Force must complete its PFAS remedial investigation and address the nature and extent of contamination throughout the site, regardless of source.”
In answer to a question from Boles, Greenberg reported that when PFAS was first identified in 2016, wells that could be affected were surveyed and found to be below the federal limits for the chemicals.
Greenberg said another contaminant, 1.4 Dioxane, also has been identified within the operating unit. So, the continuing groundwater monitoring now also includes that compound. The Air Force has directed a “plume stability study” to see if concentrations of contaminants change while the pumping station is offline.
There’s a cluster of wells for sampling and “we want to know about the source of the CVOCs (chlorinated volatile organic compounds),” he continued. “We want to know where they might be coming from and why they’re still there.”