This week the Army began its investigation to determine if the PFAS (per- and polyfluoroalkyl substances) found in the water of private wells in northwest Harvard may have come from the former Fort Devens. Engineers performed a “seismic survey” along Old Mill Road this week to understand the topography under the soil there. It plans to drill two monitoring wells in Harvard to test for PFAS: one each on Old Mill and Blanchard roads, and multiple monitoring wells to the west of those roads in Devens. If testing shows that northwest Harvard’s PFAS originated in Devens, that section of Harvard would be incorporated into the Devens PFAS cleanup site, and the Army would bear responsibility for remediation.
In 2019, at the Harvard Board of Health’s request, the Army tested private wells in Harvard near areas of known PFAS groundwater contamination in Devens. Of the 52 wells that tested positive for PFAS, 45 were in the northwest corner of Harvard, at residences on Old Mill, Blanchard, Lancaster County, and Cedar Ledge roads.
The 2019 tests showed that 14 of the northwest Harvard wells contained PFAS levels that exceed the state’s maximum contaminant level of 20 parts per trillion for the sum of six specific substances (known as PFAS6). Last month the Environmental Protection Agency finalized a more stringent maximum contaminant level for specific substances. Concentrations of PFOA and PFOS, two of the more prevalent substances found in water in this area, may be no higher than 4 ppt each. Three other substances, PFHxS, PFNA, and HFPO-DA, cannot be over 10 ppt. It is unclear how many of the Harvard wells tested in 2019 may exceed any of those limits.
Unfortunately, the Army is using state PFAS levels to guide its investigation. According to the work plan, engineers will look for a Devens source of Harvard’s PFAS only if the new monitoring wells show PFAS levels above the state’s maximum contaminant level. According to the state’s Department of Environmental Protection, it has two years to establish regulations “that are no less stringent than the federal standards,” with the possibility of a two-year extension. That process, which includes opportunities for written comments as well as public hearings, will not be a speedy one. When the state’s revisions are finalized, it is unclear if the investigation would be reopened if the work has been completed.
Suspected PFAS source is former landfill, Area of Concern (AOC) 40
The Army began testing for PFAS in the groundwater at multiple locations in Devens in 2018 as part of the process dictated by the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA). This act requires the Army to clean up contaminated sites that could be harmful to human health or the environment. Engineers identified locations with high PFAS levels as numbered areas of contamination. One area, AOC 40, is a former landfill located just over the Harvard line west of Old Mill and Blanchard roads. In 2019, tests in AOC 40 showed PFAS in the groundwater as high as 394 ppt.
According to an investigation summary published for the Army Corps of Engineers in June 2020, the old landfill known as AOC 40 contained about 110,000 cubic yards of “construction debris (masonry, asphalt, wire, and metal), ash, stumps, and logs,” spread over about 4 acres. Part of the landfill was in wetlands, which over time became submerged under Cold Spring Brook Pond.
The area was cleaned up between 2000 and 2002 as part of the initial CERCLA remediation effort at Devens. Almost 150,000 cubic yards of debris and contaminated soil and sediment were removed and disposed of at the Devens Consolidation Landfill, which was built to receive excavated material from various unpermitted landfills in Devens. But PFAS was not on anyone’s radar at that time.
Investigating the spread of PFAS
The PFAS remediation investigation, the part of the CERCLA process that defines the nature and extent of the contamination, began in 2018 when engineers drilled hundreds of monitoring wells on the former Army base to identify PFAS levels in the groundwater. This next phase of the investigation will determine whether PFAS-contaminated water is migrating outside the boundaries of Devens; northwest Harvard tests will take place this summer.
Board of Health member Chris Mitchell, a hydrogeologist, told the Press engineers will be looking to see if the aquifers supplying water to that section of town are connected to contaminated aquifers in Devens. If they are connected, they’ll be looking at the PFAS levels as the water moves from Devens to Harvard.
He said most of the existing test wells at Devens were drilled into aquifers in the “overburden,” or deep soil and gravel deposits that sit on top of bedrock. Engineers will look at the overburden aquifers in northwest Harvard, but they will also be drilling into the bedrock and testing those aquifers for PFAS. In addition, they’ll be drilling into the bedrock in the area near AOC 40 in Devens.
Mitchell said if a PFAS connection to Devens is found, it could take a long time for residents to see any remedial action, because the CERCLA process “takes forever.” He said there are emergency measures that could be put in place ahead of remedial action if the state or federal government determines that the problem is serious enough to warrant them.
