Kristi Diller is geologist with over 12 years of environmental consulting experience focused on site characterization and remediation. She specializes in complex site assessments, remedy selection, remedial design, and remedial actions at industrial and Department of Defense sites for a range of media (groundwater, soil, soil gas) and contaminants (chlorinated solvents, petroleum, metals, per- and polyfluoroalkyl substances, etc.). Ms. Diller earned a B.S. in Geological Sciences from the University of Idaho and a M.S. in Geological Sciences from Arizona State University. She is a registered geologist in the States of California and Oregon.
Expanded Site Inspection for PFAS at Burlington Air National Guard Base
An expanded site inspection (ESI) for per- and polyfluoroalkyl substances (PFAS) was conducted at the Burlington Air National Guard Base (the Base) in South Burlington, Vermont where a previous site inspection had documented the presence of PFAS in groundwater, soil, surface water, and sediment. The focus of the ESI was at six areas of concern (AOCs) where eight carbon chain based Aqueous Film Forming Foam (AFFF) may have been used or spilled during historical firefighting operations. The primary objectives of the ESI were to assess potential for PFAS migration pathways between the AOCs and downgradient receptors and to determine if there are upgradient sources that may be contributing PFAS mass to groundwater and surface water near the Base. The Vermont Department of Environmental Conservation has one of the most stringent state-promulgated Groundwater Enforcement Standards for PFAS at a value of 20 nanograms per liter individually or for the sum of five PFAS compounds: perfluorooctanoic acid (PFOA), perfluorooctane sulfonic acid (PFOS), perfluorohexane sulfonic acid (PFHxS), perfluoroheptanoic acid (PFHpA), and perfluorononanoic acid (PFNA). The ESI was designed to augment the data collected during the previous site inspection. The investigation included the collection of groundwater samples from 38 locations from shallow water table wells to deep bedrock wells. Samples were collected from 19 existing groundwater monitoring wells, and 19 additional groundwater monitoring wells were installed and sampled. In addition, one downgradient private water well used for agricultural purposes was sampled. The ESI also included collection of 13 sediment samples, 29 surface water samples, and 17 stormwater samples. All samples were analyzed for 24 PFAS target analytes, based on the PFAS compounds included in the United States Environmental Protection Agency (USEPA) draft target analyte list, using USEPA Test Method 537. Results of the investigation, including the magnitude and distribution of the PFAS contaminants at the AOCs, will be presented. The presentation will include an assessment of PFAS migration pathways at the site. In addition, lessons learned regarding implementation of a PFAS-free approach to a drilling and sampling program will be shared.