Town Received Verdantas Field Investigation and Data Analysis Summary

On March 27, 2025, the Town received Verdantas’ Field Investigation and Data Analysis Summary from MassDEP. The purpose of this report is to summarize the limited subsurface investigation and associated activities conducted between November 2024 and January 2025. This investigation was focused on identifying the presence and extent of PFAS at the Fairgrounds campus. Based on the site investigation performed, Verdantas offers the following conclusions (refer to page 13 of the report):

• The laboratory analytical results of soil samples collected indicate that PFAS6 concentrations are relatively low and are distributed relatively evenly across surficial soil at the Site and surrounding town-owned properties with no indication of a PFAS source at the surface. Furthermore, there is no evidence indicating that soil near the water table is impacted with PFAS at the locations investigated.
• The highest concentration of PFAS6 at 22.33 ng/L was detected in the groundwater sample collected from monitoring well VDT-4FG-4, which is located on the Site(4 Fairgrounds Road) and is directly behind the Nantucket Public Safety Complex building to the east. The next highest concentrations were detected at monitoring wells VDT-WAITT-12 and VDT-2FG-5 which are both located on Town-owned properties and on the Site (2 Fairgrounds Road), respectively.
• Concentrations of PFAS6 were not detected in groundwater samples collected from monitoring wells located furthest to the west and southwest of the Site.
• There does not appear to be a correlation between the concentrations of PFAS6 detected in soil samples and groundwater samples. PFOA and PFOS were detected in both soil and groundwater samples. However, the concentrations of PFOA and PFOS detected in soil samples were relatively lower than the concentrations detected in groundwater samples.
• Select non-regulated PFAS substances were detected in groundwater samples, including PFBS, PFBA, PFHxA, and PFPeA. Non-regulated PFAS substances were not detected in soil samples.
• A minimal hydraulic gradient was observed based on the results of this investigation; however, the groundwater elevation data indicates that the groundwater flow is in a northerly direction, towards Old South Road.