Date of Award
2026
Document Type
Honors Thesis (Open Access)
Department
Colby College. Environmental Studies Program
Advisor(s)
Gail Carlson
Second Advisor
Manny Gimond
Third Advisor
Philip Nyhus
Abstract
Per- and polyfluoroalkyl substances (PFAS) are highly persistent and harmful environmental pollutants. One source of PFAS in the environment is sewage sludge, which results from general wastewater treatment (Class B) or sludge treatment to remove pathogens (Class A). In Maine, the spreading of and contamination from Class B sludge is well documented, but that is not the case for Class A sludge. We used records from the Maine Department of Environmental Protection (DEP) to create ArcGIS maps documenting deliveries of Soil Prep Inc.’s N-Viro Soil® which was sold to farms across Central Maine. We sampled surface water near N-Viro Soil® delivery sites to attempt to determine a “fingerprint” of contamination. PFAS levels varied across our sites, with the highest contamination in runoff water down the hill from the now closed Soil Prep Inc. facility in Plymouth, ME (P3). The most prevalent analyte in Plymouth samples and the N-Viro Soil® itself was PFOA. Both P3 and the N-Viro Soil® had majority PFCAs (83.8% and 74.8% respectively). The samples had equal percentages of 8C analytes with more short-chain PFAS (< 8C) in P3 and more long-chain PFAS (>8C) in the N-Viro Soil®.
Keywords
PFAS, pollution, compost, biosolids, Class A sludge, surface water
Recommended Citation
Hanson, Kate I., "Environmental PFAS Contamination from Industrial Compost in Maine: The Role of Soil Prep Inc." (2026). Honors Theses. Paper 1536.https://digitalcommons.colby.edu/honorstheses/1536