The National Collaborative PFAS Project, coordinated by the University of Arizona’s WEST Center, is designed to evaluate the incidence and mobility of PFAS in soils with a history of land application of biosolids. PIs include University of Arizona’s Dr. Ian Pepper and Dr. Marc Brusseau, and Greg Kester, Director of the Renewable Resource Program at the California Association of Sanitation Agencies (CASA).

Background

EPA regards PFAS as emerging chemicals of concern due to potential adverse health effects. In 2016, the EPA Health Advisory levels for PFOS and PFOA went from a combined 600 parts per trillion (ppt) down to a combined 70 ppt. On June 15, 2022, EPA further reduced the levels to 0.004 ppt for PFOA and 0.02 ppt for PFOS. Since all biosolids contain some PFAS compounds, this has led many U.S. states to be concerned about land application of biosolids due to the potential for PFAS contamination of groundwater used as a potable water source. These concerns prompted a 2022 ban on biosolids application in Maine with other Northeastern States considering similar legislation.

Only a couple years earlier, in 2020, a temporary moratorium on land application was placed on biosolid disposal in Pima County, AZ for similar reasons. In response, researchers from the University of Arizona and Pima County Wastewater partnered to conduct an in-depth local study to evaluate risks from PFAS in biosolids.  Data showed that input of PFAS from long-term application of biosolids was minimal at local agricultural sites and concentrations decreased rapidly with depth. Due to this collaborative study, the moratorium on land application was rescinded in Pima County in November 2020 (Pepper et al., 2021).

Project Concept

Following the success of the Pima County study to evaluate PFAS risks at a local level, the University of Arizona initiated the National Collaborative PFAS Project to better understand the incidence and mobility of PFAS from biosolids in diverse environments across the country. Specifically, the study asks, “Does land application of biosolids result in significantly increased human exposure to PFAS?” It seeks to evaluate exposure risk by measuring PFAS in soils and groundwater. In a later phase, it also hopes to investigate potential plant uptake where biosolids are used as a soil amendment.

Study Objectives

1. To evaluate the incidence and mobility of PFAS analytes in soils that have received land-applied biosolids for multiple years.
2. To measure PFAS concentrations in groundwater co-located with land application sites to create paired data sets of soil and water PFAS concentrations.
3. To evaluate land application sites nationally across the U.S. with differing soils, depths to groundwater and climates, including irrigated and non-irrigated sites.
4. To utilize the collected field data to validate a screening level transport model that predicts the potential of PFAS leaching to groundwater.

Methodology

In this extensive study, the National Collaborative PFAS Project aims to enroll 25 to 30 sites from across the United States to assist with soil sampling. The team at WEST Center supports participating sites by providing a sampling kit with supplies and equipment; instructing sites regarding standardized sampling methods and protocols to prevent PFAS contamination (SOP and instructional video); and meeting with site representatives to discuss the project and answer questions.

At each site, personnel work pro-bono to sample soils within three (3) plots. Appropriate blanks (travel, field, and equipment) are also collected.

• Control plot – no biosolids
• Low biosolid rate land application plot
• High biosolid rate land application plot

For each plot, soil samples are obtained via a soil core at 1’, 3’ and 6’ depths. Three cores are taken from each plot, resulting in a total of 27 soil samples (3 plots x 3 cores x 3 depths). Whenever possible, corresponding groundwater samples are also obtained. All samples are shipped to the University of Arizona Water and Energy Sustainable Technology (WEST) Center where they are processed and subsequently analyzed for PFAS analytes at the Arizona Laboratory for Emerging Contaminants (ALEC).

Progress to Date

Project Funding

To date, a total of $450,000 in financial support has been donated by utilities, private sector companies, and non-profit organizations. This funding is being used to support sampling and analysis of soils from 25-30 sites around the country.

Sampling and Analysis

Sampling began in fall 2022 and has continued throughout 2023. As of November 2023, 20 sites from states around the country had completed sampling with an additional three (3) sites in progress (see map above). Soil characterization and PFAS analyses are ongoing.

There is still time to offer a site! UArizona continues to respond to inquiries and enroll new land application sites in the United States.