There are likely more than 57,000 sites contaminated by PFAS (per- and polyfluoroalkyl substances) in the U.S., according to a recent Northeastern University-led study published in Environmental Science & Technology Letters, but, to date, relatively few are known.
While most early PFAS attention has been focused on aqueous film-forming foam (AFFF) releases at military bases and airports, mainly resulting from firefighting training drills – there are many additional PFAS sources that have not received as much widespread attention.
Industrial facilities may account for approximately 90 percent of the probable PFAS contamination sites nationwide, according to the study. However, as PFAS contamination has either not been discovered or made public at most of these facilities, they remain hidden. Recent directives from the U.S. EPA will begin to uncover these sites, bringing more awareness to the scope of the problem relating to industry.
On April 28, 2022, the U.S. EPA issued a Memorandum directing the Office of Water to use the National Pollutant Discharge Elimination System (NPDES) to restrict PFAS discharges to water bodies. The first step in this process is to identify industrial PFAS sources through testing. For facilities where PFAS substances are expected or likely to be present in their discharge, testing for 40 individual PFAS is now required for EPA-issued NPDES permits. Some states have similar regulations on the books while most others are expected to follow. These new sampling requirements shed light on many potential industrial sources of PFAS contamination affecting surface water bodies, public drinking water systems, and wastewater treatment plants (WWTPs).
PFAS Source Zones and Groundwater Plume Development
The cause of most groundwater contamination begins with PFAS leaching, followed by contaminant plume development away from source zones. Such source zones include burn pits used for firefighting drills, leaking AFFF storage tanks, or other chemical spills containing PFAS.
PFAS releases associated with these sources often occur at or near the surface and deposit onto shallow soils. Precipitation events induce PFAS leaching downward through the vadose zone. Over time, PFAS residing in soils can be driven deep enough to reach groundwater. The forever chemicals readily move with the groundwater, forming contaminant plumes extending for thousands of feet or even miles downstream.
As the size of PFAS groundwater plumes increase, so does the risk of the chemicals contaminating drinking water wells. Containing PFAS at or near their source can prevent plume development or stop advancing plumes, eliminating PFAS exposure risks downstream.
Treating PFAS Source Zones to Prevent Drinking Water Exposures
Colloidal activated carbon (CAC) is a patented technology1 developed by REGENESIS® to contain PFAS at the source and prevent groundwater plume development. CAC works by coating individual soil grains with microscopic carbon particles milled to the size of red blood cells (i.e., 1 to 2 microns). The treatment creates an in-ground (i.e., in situ) passive filtration system where PFAS are removed as water containing the chemicals migrates through a CAC-treated zone. CAC’s effectiveness is governed by its small particle size and proprietary colloidal formula, which allows the material to distribute evenly through soils without clumping.
CAC is applied directly to the soil above the water table to prevent PFAS soil leaching and plume formation or as permeable barriers that halt advancing PFAS groundwater plumes. Optimal treatments might also involve surface capping or other soil modifications to reduce infiltrating rainwater and soil permeability. Typical treatments are designed to be effective for decades, backed by advanced modeling software2 to predict performance and a robust warranty program3.
Treating PFAS in Drinking Water: Costs and Complications
Once PFAS has contaminated a drinking water well, the situation changes from simple prevention to emergency response. At this stage, aboveground filtration is the only practical treatment method for removing PFAS in drinking water, and unfortunately, it is a costly and complicated exercise.
Drinking water treatment systems for PFAS utilize sorbents such as granular activated carbon, ion exchange resins, or reverse osmosis filters. These materials form large quantities of PFAS waste streams requiring disposal or incineration. The amount of sorbent materials needed to treat PFAS effectively is massive, primarily due to their exceptionally low drinking water cleanup targets. The most protective PFAS treatment systems aim to achieve “non-detect” with detection levels typically in the single parts-per-trillion range. According to the most recent (2022) Health Advisories issued by the U.S. EPA, any detection of certain PFAS might result in an adverse health risk.
Besides generating large quantities of spent materials, managing PFAS wastes involves further complications. For instance, many landfills and incinerators do not accept spent sorbents from these systems to avoid potential legal exposure. In September, the U.S. EPA proposed regulating two PFAS compounds, PFOA and PFOS, as hazardous substances under the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA), meaning that these filtration media will also become hazardous substances, attended by strict requirements for transportation, storage, and disposal.
These factors accumulate to make treating drinking water for PFAS at the wellhead a monetary proposition far beyond the already crimped budgets of most public water utilities. To help recoup the costs for installing, operating, and maintaining these PFAS treatment systems, some public water utilities and organizations, such as the National Rural Water Association (NWRA), have filed lawsuits against potentially responsible parties contributing to the PFAS problem. Settling these lawsuits will likely take many years.
Preventing contaminant movement away from PFAS source zones is necessary to avoid further costly drinking water impacts and protracted environmental liabilities. Since 2016, advanced CAC materials have effectively prevented PFAS movement in groundwater, containing PFAS in place and eliminating the threat to drinking water sources.
1 Commercially manufactured as PlumeStop® US Patents #7,585,132 #9,770,743, #9,776,898; #10,005,684; and SourceStop™ (patent pending)
2 PlumeForce™
3 PlumeShield®
