Hegeman Avenue PFAS Investigation

WHEM was contracted by the Islamic Society of Vermont (ISV) in 2021 to perform a Site Investigation to address an Initial Release Notification Letter provided to them by the Vermont Department of Environmental Conservation (VT DEC) in 2021 at their former property on Hegeman Avenue (SMS #2021-5056). From 1973 to 1982, the Site and neighboring property were operated by Harbour Industries (HI), a manufacturer of high temperature wire and cable for manufacturers in the aerospace, computer, and appliance industries. The manufacturing of such wire and cable often involved coating lengths of wire with a Teflon-like substance, and PFAS contamination to groundwater has been observed at another HI plant in Shelburne, Vermont. In 1981, a complaint of dumping at the Site led to a state investigation. The results of this investigation reported that, up to 1981, it was HI policy to dispose of spent solvents on the ground, particularly sandy ground. The investigation also suggested that several possible PFAS-containing solvents may have been dumped on the ground surface at the Site. Following the State investigation, HI promptly changed their waste handling policy, and closed the Colchester facility in 1982.

In February 2022, WHEM conducted a Site Investigation and oversaw the advancement of seven (7) monitoring wells and coordinated with another consultant working on an adjacent property to finish an additional three (3) exploratory soil borings as monitoring wells. In all, twelve (12) monitoring wells were sampled for PFAS, with ten of the twelve wells reporting concentrations of regulated PFAS compounds in exceedance of Vermont standards (20 ng/L, sum of 5 compounds). Informal fingerprinting of PFAS compounds conducted by WHEM at the source wells compared to other wells, both upgradient and downgradient, shows a generally consistent makeup of PFAS constituents, suggesting that the Site is being impacted by a single PFAS source, rather than multiple inputs from different historic site uses or abutting properties’ historic uses.

In March 2023, WHEM conducted an Additional Site Investigation, which included the installation of six (6) new groundwater monitoring wells, the sampling of the new wells and eleven (11) existing wells, and the collection of five (5) soil samples from areas of interest. Total PFAS concentrations exceeded the PFAS standard in fourteen (14) of the seventeen (17) wells sampled, with concentrations of total PFAS concentrations ranging from 13.8–1,750 ng/L. Soil sampling revealed low levels of PFOA and PFOS in soils near potential historic disposal areas, but well below concentrations what would constitute any kind of source. It is possible that source soils have been removed or mixed up during landscaping and redevelopment of the Site and surroundings, or that the age of the plume and lack of fine-grained in shallow soils has allowed for significant downward migration of contaminated material. 

In November 2024, WHEM conducted a Supplemental Site Investigation to expand the monitoring network. Three (3) additional monitoring wells were installed and a total of twenty-five (25) monitoring wells were sampled. The investigation continued to document widespread PFAS contamination, with twenty-one (21) of the wells reporting concentrations in exceedance of Vermont standards. Based on the concentrations and ratios of PFAS compounds present, WHEM determined that the PFAS contamination stems from one or more releases at the former HI locations. As of October 2025, VT DEC is determining potential next steps for the Site.

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