PFAS – per- and polyfluoroalkyl substances – are rapidly becoming one of the most discussed issues in contaminated land.

Often referred to as “forever chemicals”, PFAS are not one contaminant but a very large group of synthetic chemicals that have been used for decades across industrial processes, firefighting foams and a huge range of commercial and consumer products.

Their properties made them incredibly useful.

Unfortunately, many of those same properties make them particularly difficult to manage once they enter the environment.

PFAS can be highly persistent, some are mobile in water, conventional remediation techniques may not be effective and regulatory expectations continue to develop.

For anyone involved in owning, acquiring, developing, investigating or excavating land, this raises an obvious question:

What does PFAS actually mean for my project?

The answer depends very much on where you sit in the development process.

First: what are PFAS?

PFAS stands for per- and polyfluoroalkyl substances.

They are a large family of synthetic fluorinated chemicals developed because of properties including resistance to heat, water, oil and chemical degradation.

Those characteristics resulted in their use in applications ranging from firefighting foams and industrial processes to coatings, textiles, packaging and consumer products.

The term PFAS therefore describes a family of substances rather than a single contaminant.

Some of the better-known compounds include:

PFOS – perfluorooctane sulfonic acid

PFOA – perfluorooctanoic acid

PFHxS – perfluorohexane sulfonic acid

PFNA – perfluorononanoic acid

These are only a small part of the wider PFAS family.

The important point from a contaminated land perspective is that PFAS behave differently from many of the contaminants the industry has traditionally dealt with.

Their persistence, potential mobility and very low concentrations of regulatory interest can make investigation, risk assessment, remediation and waste management challenging.

Why are we talking about PFAS now?

PFAS contamination isn’t new.

Our understanding of it is.

Historical use means PFAS may already be present within soil, groundwater, surface water, infrastructure and waste streams associated with sites that have been operating for decades.

At the same time, scientific understanding, analytical capability and regulation are developing quickly.

The UK Government published its PFAS Plan in February 2026, setting out actions around understanding PFAS sources, tackling pathways and reducing exposure.

CL:AIRE has also progressively developed resources for the contaminated land sector, including guidance on managing PFAS risks and liabilities, identifying potentially affected sites, interim soil screening levels and, most recently, TB23 and a worksheet tool relating to the new European environmental quality and groundwater standards.

The direction of travel is therefore clear.

PFAS is becoming an increasingly important consideration in land and water management.

That does not mean every site suddenly has a PFAS problem.

It means we need to become better at identifying when PFAS is a credible consideration and responding proportionately.

CONTINUES BELOW… 

Where might PFAS be found?

This is where understanding the history of a site becomes particularly important.

Potential PFAS sources can include sites associated with:

• firefighting and fire training
• airports and aviation
• fuel storage and distribution
• chemical manufacture
• metal finishing and plating
• textiles and surface treatments
• paper and packaging
• waste management
• wastewater treatment
• certain manufacturing processes

One of the most recognised sources is the historical use of aqueous film-forming foam (AFFF) for fighting hydrocarbon fires.

That means sites where firefighting foam was repeatedly used, stored, tested or discharged can warrant particular consideration.

However, PFAS use is extremely broad and a site does not necessarily need an obvious chemical manufacturing history for PFAS to be relevant.

That makes a good conceptual site model particularly important.

I’m a landowner – what do I need to know?

The first point is:

Don’t assume that PFAS is somebody else’s problem.

Understanding historic land use is increasingly important when assessing environmental liability.

If a site has a plausible PFAS source, the questions should include:

What activities historically took place here?

Could PFAS-containing materials have been used?

Could PFAS have entered soil or groundwater?

Could contamination have migrated beyond the site boundary?

Could neighbouring activities have affected my land?

What does this mean for the current or future use of the property?

This becomes particularly important when selling, refinancing or redeveloping land.

Discovering a potential PFAS liability during a transaction or, worse, during construction can create considerably more uncertainty than understanding it beforehand.

The objective shouldn’t necessarily be to undertake PFAS testing on every site.

It should be to identify whether there is a credible source-pathway-receptor relationship that warrants further assessment.

I’m a developer – what do I need to know?

For developers, the biggest issue is often uncertainty.

A PFAS issue identified early can be investigated, assessed and incorporated into the development strategy.

A PFAS issue discovered once excavation has started can become a very different commercial problem.

Potential consequences include:

• additional investigation
• changes to remediation strategy
• restrictions on soil reuse
• additional groundwater management
• changes to earthworks sequencing
• unexpected waste classification requirements
• reduced disposal options
• additional treatment
• programme delays
• regulatory engagement
• increased cost

PFAS therefore needs to be considered alongside other ground risks during acquisition, planning and pre-construction.

This doesn’t mean automatically adding PFAS analysis to every ground investigation.

It means asking the right question early enough:

Is there a credible reason why PFAS might be present on this site?

If there is, establishing the risk before fixing the earthworks and remediation strategy can be considerably less expensive than discovering it afterwards.

I’m a consultant – what do I need to know?

For environmental and geotechnical consultants, PFAS introduces some important considerations.

Perhaps the most fundamental is that a conventional analytical suite does not necessarily tell you whether PFAS is present.

If the desk study identifies credible PFAS sources, the investigation strategy needs to consider whether PFAS-specific assessment is appropriate.

But sampling for PFAS isn’t simply a matter of adding another line to a laboratory schedule.

PFAS are present in numerous everyday materials and products, meaning careful sampling protocols and quality assurance are important to minimise the potential for cross-contamination.

The conceptual site model remains fundamental.

Consider:

Source – where could PFAS have originated?

Pathway – how could it migrate?

Receptor – what could potentially be affected?

For some sites, groundwater and surface water pathways may be particularly important because of the mobility of certain PFAS.

Investigation therefore needs to answer a question rather than simply generate analytical data.

And because regulation and technical understanding are continuing to develop, assumptions and limitations should be clearly communicated to the client.

I’m a contractor – what do I need to know?

For contractors, PFAS can quickly move from an environmental issue to a delivery issue.

Imagine excavating a significant volume of soil that the tender information assumed could be reused on site.

PFAS is subsequently identified.

Suddenly several questions arise:

Can the material still be reused?

Does it constitute waste?

Can it leave site?

Where can it go?

Will the proposed receiving facility accept it?

Does it require treatment?

What happens to the programme while this is resolved?

That is why understanding the basis of the remediation and materials management strategy before excavation starts is so important.

Contractors should be particularly cautious about accepting broad contractual responsibility for unforeseen contamination without understanding the underlying investigation and risk assessment.

If PFAS is a credible risk, it should be identified, allocated and managed before large-scale earthworks begin wherever possible.

What about soil reuse?

This could become one of the more commercially significant areas for brownfield development.

Modern earthworks and remediation strategies increasingly seek to retain and reuse suitable site-won soils rather than automatically exporting them as waste.

That is generally positive.

It reduces vehicle movements, landfill dependency, imported aggregate requirements, carbon emissions and cost.

But reuse needs to be demonstrably suitable.

Where PFAS is identified, simply knowing that it is present doesn’t necessarily answer whether material can or cannot be reused.

The decision needs to consider factors including:

• concentration
• the PFAS compounds present
• material characteristics
• proposed location of reuse
• receptors
• groundwater and surface water pathways
• the overall conceptual site model
• applicable regulatory requirements

This is another reason why early assessment matters.

A materials management strategy designed without considering a credible PFAS risk may have to be reconsidered later.

What if the soil needs to leave the site?

This is where PFAS can have significant practical and commercial consequences.

Once material becomes waste, the waste producer has responsibilities for understanding and correctly describing that waste.

PFAS should therefore not be treated purely as a WAC-testing issue.

Waste classification and landfill acceptance are different processes.

The first question is what the waste is.

The next is where it can lawfully and practically go.

Certain PFAS are already regulated as Persistent Organic Pollutants (POPs), bringing additional waste management requirements where relevant concentration limits are reached.

That distinction matters because POPs waste can be subject to requirements for the POP content to be destroyed or irreversibly transformed rather than simply moved elsewhere.

Even where material is not POPs waste, the presence of PFAS may affect the willingness or ability of particular facilities to accept it.

Therefore:

Don’t excavate thousands of tonnes of potentially PFAS-affected soil and assume that a disposal route will be available afterwards.

Characterise the material and understand the receiving route first.

Can PFAS be remediated?

Yes – but it can be challenging.

Traditional remediation techniques used for contaminants such as hydrocarbons are not necessarily effective for PFAS.

Depending on the site, media, concentrations and objectives, management approaches may include:

• excavation and off-site management
• containment
• immobilisation or stabilisation
• soil washing or separation technologies
• groundwater extraction and treatment
• adsorption technologies such as activated carbon or ion exchange
• specialist destructive treatment technologies

There is no universal PFAS remediation solution.

In many cases the real question isn’t:

“How do we remove every trace of PFAS?”

It is:

“What intervention is necessary to manage the identified risk in a proportionate, sustainable and technically defensible way?”

That distinction is important.

Should every site now be tested for PFAS?

In my view, no.

PFAS should not become another box that is automatically ticked on every ground investigation.

Good contaminated land management remains risk based.

The starting point should be understanding the site’s history and developing a robust conceptual site model.

Where credible PFAS sources or pathways exist, further investigation may be entirely appropriate.

Where they don’t, indiscriminate testing can generate data without necessarily improving decision-making.

The objective should be better information, not simply more information.

Five questions I would ask about a site today

If I were acquiring, developing, investigating or tendering a brownfield site, I would want answers to five relatively simple questions:

1. Is there a credible historic or current PFAS source?
2. If PFAS could be present, has the investigation actually considered it?
3. Could groundwater or surface water provide an important migration pathway?
4. What would PFAS mean for the proposed remediation, earthworks and soil reuse strategy?
5. If material has to leave site, do we understand its classification and have we established a viable receiving route?

If those questions have been considered early, PFAS becomes another risk that can be managed.

If they haven’t, it can become an expensive uncertainty.

PFAS isn’t just an environmental issue

Perhaps this is the most important point.

PFAS sits at the intersection of:

environmental risk, regulatory compliance, land value, design, earthworks, waste management, programme and commercial risk.

That makes it relevant to far more people than contaminated land specialists.

The regulatory and technical landscape will undoubtedly continue to develop.

The response shouldn’t be panic or indiscriminate testing.

It should be a better risk assessment.

Understand the history.

Identify credible sources.

Develop the conceptual site model.

Investigate proportionately.

Understand the implications for materials and waste.

And do it early enough that the project still has options.

Because, as with most ground risk, the expensive part is rarely identifying the problem.

It’s discovering it too late.

Concerned PFAS may affect a site? Grounded can review the available site information and help determine whether further assessment is warranted.

Grounded. Contaminated Land Solutions

Helping landowners, developers, consultants and contractors understand and manage contaminated land risk from investigation through to remediation, materials management and verification.