Nantucket Memorial Airport begins Phase 4 PFAS scoping to target soil remediation near runways

Madison Collins, the airport’s environmental coordinator, told the Nantucket Memorial Airport Commission on June 17 that the airport is launching Phase 4 scoping to better locate per- and polyfluoroalkyl substances (PFAS) in soil and measure leaching toward groundwater.

Collins said engineers plan two kinds of sampling: lysimeters to capture soil moisture fluxes and targeted soil samples—“15 shallow locations and 4 deep locations”—to map vertical extent. She said the goal of the testing is to “support a reduced footprint and shallower depths for soil remediation.”

The testing will guide whether active remediation (excavation and soil washing or a treatment called Florasorb tilling) or monitored natural attenuation is appropriate at each location. Collins described excavation and soil washing as “much higher cost and will be much more destructive,” and said Florasorb tilling is a lower-cost, less-disruptive option that “will help ... bind to the PFAS and freeze it where it is, so it prevents further leaching into groundwater.”

Jim (consultant), who discussed how lysimeters work, said the team plans a two-phase installation, with five or six lysimeters placed in the first phase and others held in reserve pending initial results. “What the lysimeters are is essentially it's a monitoring well that you complete in the unsaturated zone,” he said, describing how the device collects soil moisture over days for PFAS analysis. He added, “Ultimately, what we wanna do here is clean up the groundwater. Right? That's our — that's our risk pathway is people drinking the groundwater.”

Airport Manager Smith told the commission that McFarland Weston Solutions is the subconsultant performing PFAS services under a McFarland Johnson contract amendment included in the contracts packet; that amendment was approved as part of the multi-item contracts motion later in the meeting. Smith also reported that three affected homes have been connected to municipal water since the last meeting and that bottled-water deliveries for those homes have stopped because MassDEP rules exempt homes on town water.

Why this matters: PFAS are persistent chemicals linked to health concerns, and the airport’s sampling and remediation choice will determine the size, cost and community impact of cleanup work. Commissioners asked about the number and depth of samplers and whether remediation would focus only on soils that contribute to groundwater contamination.

The commission did not adopt a remediation decision at the meeting; the work described is planning and sampling to define a targeted remediation strategy. Staff said monitoring and staged sampling will precede any broader excavation-based work, and that monitored attenuation is being considered for nondrinking-water-source areas.