SITE INVESTIGATION OF A PFAS-IMPACTED FIREFIGHTER TRAINING FACILITY IN SOUTHWEST VERMONT

The State-owned Vermont Fire Academy, located in southwest Vermont, used aqueous film-forming foams (AFFF) for firefighter training from the 1990s until 2011 when a fluorine-free training foam was introduced. In 2016 a release of per- and polyfluoroalkyl substances (PFAS), primarily perfluorooctanesulfonic acid (PFOS), was identified in near-surface soils. Subsequent investigation beginning in 2020 identified a PFAS-contaminated vadose zone up to 30 meters thick comprised of glaciolacustrine sand and gravel overlying basal till interpreted as a kame terrace. The site is underlain by Neoproterozoic-lower Cambrian metawackes and dolostones of the Pinnacle Formation (CZpw) and Forestdale Formation (CZfd), respectively. On-going investigation activities are focused on 1) potentially impacted drinking water and/or surface water receptors, and 2) defining the extent of impacted groundwater with the goal of supporting a groundwater reclassification pursuant to the Vermont Groundwater Protection Rule and Strategy. Additional site features include a large PFAS-contaminated concrete training pad and underground concrete water reclaim tank used to support firefighter training events. The training grounds are served by municipal water unimpacted by PFAS; however, the training activities require the capture of meteoric water for use in training purposes under the site’s Act 250 Land Use Permit first issued in 1988. The water reclaim tank was historically discharged to the ground surface and has included a permanent effluent treatment system since 2020 utilizing granular activated carbon. Soil and groundwater investigations are being conducted by the Vermont Department of Buildings and General Services under the oversight of the Vermont Department of Environmental Conservation, with geophysical (Tromino™ passive seismic) and detailed structural mapping data provided by the Vermont Geological Survey. The latest conceptual site model will be shared along with challenges related to the site geology and release mechanisms.