Meet Andy Horn

Presenting for Rocky Mountain Association of Environmental Professionals

Geotech Field Days - Friday, June 29th, 2025

5:00pm - 7:00pm

Speaker:
Andy Horn, MSc., PG - Westwater Hydrology LLC

Abstract:
Per- and polyfluoroalkyl substance (PFAS) sampling and analysis procedures have evolved greatly over the past decade. Due to the potential presence of PFAS in consumer goods and sampling materials and sub-part-per-trillion detection levels, many PFAS sampling standard operating procedures (SOPs) have been based on a highly restrictive “precautionary principle” intended to prevent sample contamination by PFAS from sampling materials or other sample bias. The resulting SOPs frequently prohibited items such as water resistant field logbooks, Post-it Notes®, or insect repellents, from sampling activities. Research on PFAS in common sampling materials and their likelihood of contaminating samples has shown a more practical “pathways to contamination” approach can be used for most projects as long as sample media do not contact materials known to contain PFAS. Additionally, PFAS laboratory analytical methods have changed from one drinking water method and multiple proprietary laboratory-modified methods for wastewater and groundwater, reporting only a few PFAS compounds, to multiple EPA-validated analytical methods reporting up to 40 compounds.

This presentation will discuss the two PFAS sampling paradigms, analytical methods, and their applicability to various project types. Mr. Horn will share his experience as a contributor to two National Groundwater Association (NGWA) PFAS sampling and analysis task groups, one in 2017, and a subsequent 2023 NGWA task group drawing on recent research to develop a more practical guide to PFAS sampling.

Biography:
Andy Horn, MSc., PG, has been an environmental and water resource consultant for over 30 years. He has served on a variety of professional society boards and working groups including multiple National Groundwater Association PFAS task groups. He has written highly rigorous as well as more practical PFAS sampling SOPs, and has presented on PFAS technical and regulatory issues and the state of major PFAS litigation. He is a current contributor to a NGWA PFAS source identification white paper task group. Andy has performed environmental investigations at hazardous waste sites and facilities including US EPA Superfund, manufacturing, fueling & maintenance, and chemical manufacture, storage, & distribution and for basic scientific research. His areas of expertise include data collection program design and management for environmental and water resources investigations, data analysis and synthesis, and study results reporting and presentation. Andy earned his Bachelor of Science in Geology from the University of Alabama in 1990 and his Master of Science from the University of Colorado, Boulder in 1997.