Nationwide studies since the early 2000s indicate that PFAS exist in influent, effluent and residuals (biosolids) of wastewater treatment plants (Bogdan, D. 2021). Some of the most frequently detected PFAS compounds are PFAAs (perfluoroalkyl acids). This makes wastewater treatment plants important in managing and mitigating the environmental spread of PFAAs and a key participant in protecting both human and environmental health.

In Delaware, various wastewater streams (domestic, industrial and municipal) are treated and discharged into surface water bodies (NPDES discharges) as well as onto the ground surface, where it infiltrates the soil and ultimately enters groundwater (on-site wastewater discharges). Additionally, biosolids are land applied at numerous sites across the state, which also has the potential to impact groundwater.

Statewide Studies of PFAS in Wastewater

DNREC’s Water Resource Protection team has started statewide studies of PFAS related to wastewater treatment and utilization.

As these studies are completed, data summaries and other reports will be posted on this page.

Biosolids were selected to be examined first under a Biosolids Project Design and Sampling Plan. From December of 2022 through the summer of 2024, samples of biosolids (before being land applied), soils (from a selected land application site) and groundwater (from the monitoring wells installed at the selected site) were collected.

In October of 2024, a second biosolids study was initiated. This study examines PFAS in groundwater associated with long-term Class B biosolids land application sites. This study will help DNREC better understand the impacts of biosolids land application to shallow groundwater resources.

During the summer of 2024, field sampling of wastewater influent, effluent and discharge receival media (soil and groundwater) was completed, under a Project Design and Sampling Plan for Wastewater.  

Sampling of pump-outs from septic systems was completed in the summer of 2023, under a Project Design and Sampling Plan for septages.

Pilot Site Study: James Thompson Fabric Processing Plant

Upon the receipt and evaluation of the laboratory analysis results from the initial of sampling of the PFAS in Wastewater study, James Thompson — a fabric processing plant with an onsite wastewater treatment and disposal facility — was selected as a pilot site for further investigations due to elevated PFAS in samples from the plant.

A Project Design and Sampling Plan was developed. Additional samples of groundwater, surface water, sediment (from wastewater storage pond) and domestic wells downgradient of the facility were collected in the spring of 2024. A Data Summary Report of this pilot study was prepared.

Related Topics:  EPA, GenX, HSCA, PFAS, PFOA, waste and hazardous substances, wastewater, watar, water