Tetra Tech, an environmental consulting firm that has been handling testing and mitigation of per- and polyfluoroalkyl substances (PFAS) at the area of Martha’s Vineyard Airport, has finished phase one of its initial site investigation (ISI).
After private wells near the airport tested positive for levels of PFAS above the threshold of 70 parts per trillion (PPT), Tetra Tech began an in-depth analysis of private wells and groundwater flow near the affected area.
According to correspondence from Tetra Tech to the MassDEP, the first phase of the investigation yielded a “robust data set.”
Tetra Tech has sampled and analyzed 21 groundwater monitoring wells, along with 193 private wells since PFAS was discovered at the airport.
“PFAS impacts to source area soils are not significant, and further assessment of soils will be limited” in the scope of work for phase two of the investigation, the letter reads.
In areas where aqueous film-forming foam concentrates (AFFF) containing PFAS were released, the letter states, additional investigation of groundwater impacts will be warranted.
Deeper groundwater monitoring wells will be installed to assess the impact of PFAS on groundwater flow at various depths.
Additional wells will also be installed where elevated concentrations of PFAS were detected in a monitoring well but PFAS was not detected in surrounding private wells.
These wells will be installed at various depths in order to determine flow paths of PFAS in groundwater.
According to the projected milestone schedule in the letter, monitoring and mitigation efforts will continue until September 2022.