The Martha's Vineyard Times Martha’s Vineyard Airport is working with environmental firm Tetra Tech to monitor and mitigate PFAS pollution caused by aircraft firefighting foams. The Martha’s Vineyard Airport Commission is continuing to work with consulting and engineering firm, Tetra Tech, to monitor private wells for per- and poly-fluoralalkyl substances (PFAS), and treat them with filtration systems if the compounds are found at higher concentrations above 20 parts per trillion (PPT). Environmental engineer for Tetra Tech, Ron Myrick, said at Thursday’s commission meeting that for the past three years, his company has periodically tested private wells and sample wells dug specifically for monitoring PFAS as it spreads with groundwater flow. Activated charcoal filtration systems have also been installed at private wells with higher levels of PFAS.