Because disposed materials containing per- and polyfluoroalkyl substances (PFAS) enter the waste management system, landfills are considered passive receivers of PFAS. In 2022, a group of 48 landfill owners and operators hired Barr to organize and help implement a study to obtain reliable and consistent data regarding the presence and concentration of certain PFAS in groundwater at Minnesota landfills.
This innovative study provided the participating facilities flexibility in utilizing site-specific sampling methods and crews within a thoughtful study framework. We generated a robust dataset, backed by site-specific information, to examine corresponding upgradient groundwater quality data with land uses and downgradient groundwater quality data with landfill waste types and liner statuses.
StudyEach of the 48 participating landfills developed site-specific sampling plans, collected two rounds of groundwater samples from their selected monitoring wells, and provided site-specific details to inform the evaluation of the study data set.
Barr provided sampling guidance to the participating facilities, coordinated with a certified laboratory for the analysis of all the study samples using consistent analytical methods and reporting limits, prepared online surveys to collected supporting information from each facility, conducted the PFAS data quality review, and prepared the study report. The participating landfills, monitoring wells, and groundwater sample data were maintained under confidentiality.
ResultsThe study categorized upgradient PFAS concentrations by area land use categories and downgradient PFAS concentrations by landfill waste types and landfill liner status. The study results showed that:
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Regulated PFAS were found to be more prevalent upgradient of landfills with upgradient industrial/solid waste or agricultural uses than residential/undeveloped uses.
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Landfill bottom liners effectively manage solid waste containing PFAS. The PFAS concentrations in groundwater met promulgated state groundwater samples downgradient of the lined landfill cells and approximately half of the unlined landfill cells.
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Concentrations of PFAS did not strongly correlate with concentrations of traditional routine groundwater monitoring parameters; however, comparison of traditional routine groundwater monitoring parameter data versus non-promulgated screening criteria is a conservative and effective method for identifying potential landfill releases that may minimize the need for routine PFAS groundwater monitoring.
Final reportBarr’s final published report provided the participating landfills with a better understanding of how groundwater conditions compare with those at other solid waste facilities in Minnesota. The Minnesota Landfill Coalition has shared the report within the solid waste industry and regulatory agencies to advance understanding about the effectiveness of solid waste facility practices.
Click here to read the final report.