PFAS Site Characterization Learning Objectives Site Characterization Issues

PFAS Site Characterization

Learning Objectives Site Characterization Issues Relevant to PFAS Initial Site Steps Investigation Data Analysis and Interpretation Source Identification 2

Site Characterization Issues Relevant to PFAS Focus on Groundwater Historical view Plumes may be quite extensive Monitoring point construction Widespread use Compound suite Geologic heterogeneity 3

Site Characterization Issues Relevant to PFAS Evolving State Science and Regulations: of the Science Analytical Methodologies Sampling Methodologies Regulatory Environment 4

Site Characterization Issues Relevant to PFAS Unique Source, Fate, and Transport Properties Atypical Broad Sources Variety of Unusual Primary Sources “Secondary Atypical Sources” Pathways Complex transitions between media Partitioning 5

Initial Steps Drinking Water Might be first indication (e. g. , UCMR) Might require prioritization/Point-of-Use treatment Preliminary Potential Initial Assessment Reconnaissance Sampling Conceptual Site Model Receptor Surface Identification Water Body Secondary Sources 6

Site Investigation Development Geological of Site-Investigation Workplan and Hydrogeological Investigation PFAS-Specific Nature Tools for Site Screening or Characterization of PFAS Sources 7

Site Investigation Nature of Secondary PFAS Sources Leaching from the Vadose Zone Back-diffusion Desorption NAPL Dissolution Other Sources Atmospheric Deposition Overland Runoff Groundwater Seepage into Surface Water or Vice-Versa Subsurface Features, including Utility Lines Multicomponent Mixtures Precursors 8

Site Investigation Development Geological of Site-Investigation Workplan and Hydrogeological Investigation PFAS-Specific Tools of Site Screening or Characterization Nature of PFAS Sources Extent of PFAS 9

Data Analysis Retardation Mass Coefficients and Travel Time Flux/Mass Discharge Contributions from Different Sources Atmospheric deposition Vadose-zone percolation Back-diffusion Upgradient site contributions Alternate Sources 10

Data Analysis Transformation Pathways and Rates Radial diagrams showing the production of various PFAAs in the vicinity of an oxygen infusion zone at an AFFF release site remediated for hydrocarbons in groundwater Source: G. Carey, Porewater Solutions, used with permission 11

Data Analysis Assessing Modeling Plume Stability PFAS Fate and Transport Visualization Fence diagrams 3 D Models Bar charts Radial Methods diagrams Image from Wood Environment & Infrastructure Solutions, Inc. – used with permission of client 12

Source Identification Tools Chemical fingerprinting Multivariate Isomer TOP Statistical Analysis Profile Evaluation Assay Quadrupole Challenges Time-of-Flight Mass Spectrometry (QTOF-MS) and Reasonable Expectations 13