PFAS (per- and polyfluoroalkyl substances) are a large family of synthetic chemicals used for decades because they repel water, grease, and heat. The problem is that many PFAS are highly persistent in the environment and can migrate from soil into groundwater and surface waters—often creating long-term liabilities for industrial sites, airports, landfills, training grounds, and any location linked to PFAS-containing products (notably firefighting foams).
This article explains what PFAS are, where they come from, how to figure out a sampling plan, and which remediation pathways are realistic.
What exactly are PFAS?
PFAS is an umbrella term for thousands of fluorinated chemicals. Many are “surfactant-like,” which means they can move in water and interact with soils and organic matter in different ways. Their carbon–fluorine bonds are extremely stable, which contributes to their persistence and why they’re often called “forever chemicals” due the difficulty of their treatment.
Why PFAS are so hard to manage?
PFAS challenges rarely come from one single issue—it’s the combination:
- Many compounds, different behavior: some bind to soil, others travel fast in groundwater
- Low regulatory thresholds in some jurisdictions: especially drinking water
- Analytical complexity: avoiding contamination and selecting the right lab method
- Remediation tradeoffs: capturing PFAS is easier than destroying PFAS (and so far the most applied techniques); destruction options can be expensive and high energy consumption
Common PFAS sources and pathways (soil → groundwater)
Most PFAS investigations begin with identifying potential source categories such as:
- AFFF firefighting foam use: airports, industrial sites, training areas. Even the fact that they have been banned for years
- Industrial facilities: chemical manufacturing, metal plating, textiles, paper/packaging
- Landfills and waste handling: leachate can be a long-term source
- Wastewater and biosolids: site-dependent, but important for some catchments
From a conceptual site model standpoint, PFAS typically move through:
- Surface release or historical disposal
- Retention in shallow soils: varies by PFAS type and soil properties
- Leaching to groundwater: especially where infiltration is significant
- Migration along groundwater flow paths: potentially to receptors like wells or surface waters
The regulatory context
PFAS regulation is moving quickly, and the direction is consistent: more compounds, lower thresholds, more accountability.
United States: Drinking water standards (NPDWR)
In April 2024, the US EPA finalized the first enforceable national drinking water regulation for PFAS. It set MCLs of 4 ppt for PFOA and PFOS, and 10 ppt for PFNA, PFHxS, and HFPO-DA (GenX), plus a Hazard Index approach for mixtures involving PFHxS, PFNA, HFPO-DA, and PFBS.
EU: Restrictions and tightening controls
In Europe, regulators are progressing toward broader restrictions and product controls on PFAS, with ongoing work under ECHA and additional targeted restrictions (for example, on PFAS in firefighting foams).
What this means for site owners/operators: PFAS is increasingly treated as a long-tail environmental liability—and sites that wait often end up reacting under tighter timelines and higher costs.
How to test PFAS properly
PFAS sampling fails most often for two reasons:
- No site-specific sampling strategy: poor conceptual site model
- Cross-contamination: during sampling/handling
Step 1: Build a PFAS-specific sampling plan
A defensible plan typically defines:
- Likely sources (AFFF areas, process areas, storage, waste zones)
- Target media (soil, groundwater, surface water, sediment, wastewater—site dependent)
- Data Quality Objectives (screening vs compliance vs remedy design)
- QA/QC approach (field blanks, trip blanks, duplicates, equipment blanks)
The ITRC guidance emphasizes PFAS-specific sampling protocols and the need to prevent PFAS-containing materials from contacting samples (certain water-resistant coatings, etc.).
Step 2: Choose analytical methods that match your matrix
For non-potable waters, soils, biosolids, and tissues, EPA Method 1633A (December 2024) supports multi-matrix PFAS analysis via LC-MS/MS.
Tip: Don’t let a lab “pick a PFAS panel” without aligning it to your site history and regulatory needs. The “right” list depends on known sources (AFFF vs industrial fluoropolymers), receptors, and jurisdiction.
Step 3: Interpret results with transport in mind
PFAS results are not just numbers. For decision-making you typically want:
- Spatial distribution (source zones vs plume)
- Vertical profiling (shallow vs deeper units)
- Trends over time (is the source still active?)
- Geochemistry/soil properties (can influence partitioning and mobility)
PFAS remediation: multi-component instead of “silver bullet”
PFAS remedies are usually designed around three goals:
- Stop or reduce ongoing releases (source control)
- Prevent exposure (risk management)
- Reduce mass or plume (treatment/removal)
Because PFAS can be persistent and mobile, remedies are often multi-component rather than a single “silver bullet.”
1) Source control
Before choosing a treatment technology, the fastest gains often come from:
- Eliminating ongoing PFAS inputs (process change, foam management, waste controls)
- Controlling stormwater/runoff pathways
- Isolating highly impacted soil “hot spots”
- Managing landfill leachate or wastewater contributions (as applicable)
2) Ex-situ soil options
Depending on site constraints and contaminant distribution:
- Excavation + off-site disposal (effective for hot spots; needs disposal pathway and cost planning)
- Soil washing/separation (can reduce mass in some contexts)
- Thermal treatment (site- and vendor-specific; requires careful evaluation of efficacy, emissions, and cost)
Industry and guidance reviews emphasize that PFAS chemistry can make traditional soil remedies less effective and push projects toward integrated, site-specific strategies.
3) Groundwater treatment
Common approaches include:
- Pump-and-treat with:
- Collodial Activated Carbon (CAC)
- Ion Exchange (IX) resins
- Reverse osmosis / nanofiltration (high removal, but generates concentrate)
- Targeted hydraulic control near receptors (e.g., drinking water wells)
- Emerging/adjunct methods (site-specific): separation processes such as foam fractionation for certain matrices
ITRC’s PFAS guidance compares remediation approaches and highlights that treatment selection depends on matrix, PFAS types, concentration ranges, and waste management needs.
4) In-situ approaches
In-situ remedies often focus on immobilization and flux reduction rather than “destruction,” using sorbents or amendments designed to reduce PFAS mobility. Some projects also explore in-situ methods that enhance capture in impacted groundwater zones, depending on site conditions and regulatory acceptance.
Reality check: Many PFAS programs succeed by controlling migration, while long-term destruction strategies are evaluated in parallel.
Need a PFAS plan?
PFAS behaves differently in soil and groundwater, so effective programs start with a clear site model and an action plan for both media.
FAQ
Are PFAS only a “water problem”?
No. Soil can store PFAS mass and act as a long-term source to groundwater. Many programs treat soil and groundwater together through the conceptual site model and remedy design.
Can PFAS be fully removed from a site?
It depends on site scale, PFAS types, and matrices. Hot spots may be removed; plumes can be controlled and treated; long-term management is often required.
What’s the biggest mistake companies make with PFAS?
Starting with technology before establishing a PFAS-specific sampling program and a defensible conceptual site model.
Next step: make PFAS manageable
PFAS projects become manageable when you treat them like any other complex environmental issue: define the problem, get representative data, prioritize receptor protection, and choose remedies that match site reality—not marketing claims.
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