TINKHAM GARAGE

As of September 2025, the Tinkham Garage Superfund site is considered ‘Insufficient Data to make a Human Exposure evaluation’ (HEID) because of emerging contaminants (1,4-dioxane and PFAS) currently found in groundwater (GW), surface water (SW), and drinking water downgradient of the Site. A full characterization of the Site source areas is not complete. The Site was previously categorized as Human Health Exposure Under Control via a protective remedy as volatile organic compounds (VOCs) in soils and groundwater were initially, but limitedly, addressed via several treatment technologies. The Groundwater extraction and treatment was modified to MNA to address migration of VOCs to the neighborhood. Currently there remains VOCs greater than MCLs within the Site, and uncontrolled migration of 1,4-dioxane and PFAS in groundwater and surface water. There remains insufficient data from the Site to make a complete Human Exposure Evaluation. EPA uses this Human Exposure status when there is a lack of evidence to suggest that actual or reasonably anticipated human exposures are occurring and that those exposures are above acceptable risk-based levels. The on-going activities include a RI/FS to assess residual VOCs, 1,4-dioxane and PFAS in Site media, including groundwater, leach fields, soils, sediments and surface water and to perform a risk assessment to evaluate these emerging contaminants and potential exposure pathways at the Site. EPA completed a risk evaluation for these contaminants in drinking water and determined there to be an unacceptable risk. An Interim ROD was signed on September 30, 2025, to require the extension of a nearby water line and connection of nearly 90 households for the provision of a clean, alternative water source. In the meantime, residents were supplied with bottled water as a temporary mitigation measure. EPA anticipates that there will be sufficient data to make a Human Exposure evaluation by September 2030 because that is the expected completion date for the RI/FS.