In Situ PFAS Remediation: Lessons Learned from a Decade of Success

Do you really think a barrier will last hundreds of years?

In some cases, for some species, quite possibly.

The calculations and logic for the examples I presented are informal papers in the public domain, so we can read these and decide for ourselves if we agree with them.

But for sources with moderate to high flux, that’s expected to be ongoing flux, as a company Regenesis will typically design for less, perhaps 25 to 30 years, and this be more cost effective as it allows the reapplication in 30 years to be tailored more precisely to the actual flux and conditions at that time and it also means that the upfront spend is less.

 

You argued for PFAS remediation by retention in place. Isn’t there a risk that all PFAS will come out again? And then similarly, you know, PFAS are retained in place. What will happen eventually? Won’t all the PFAS come out again as a secondary source?

Okay, I think there are really two parts to these questions which are related but distinct. First, is there a risk the retained PFAS will be released again? And second, is this going to become a points. What is the direction of equilibration? And what are the kinetics or rates of any change?

So in terms of the direction of equilibration, this is a remediation exercise. We’re putting carbon into the plume. So mass is going to transfer from the dissolved phase to the sorb phase, from the plume to the carbon.

And the reduced contaminant concentration in groundwater becomes the new stable point. In other words, it’s about the order of operations. When you spill into a peat layer, for example, it’s going to equilibrate out and you get a secondary source as we might be familiar with from other remediation exercises.

But when you put the carbon into a spill, it equilibrates in. This means in terms of groundwater concentration, you have a sink and not a source.

The second part of the question, I think, was, is the mass going to come out eventually? Well, I think you first have to ask how long is eventually.

And here it’s important to distinguish between practical and absolute. Ultimately, this is a question of rates. If you run it to infinity, we can anticipate a weathering of the CAC and a reduction in its sorptive capacity.

But how slow is this? And specifically, how does the rate of weathering compare to the rate of capture? If we’re looking at geological weathering or indeed any realistic scenario, we’d certainly not be seeing a return to pre-remediation conditions.

We’d still be looking at overall flux reductions, overall concentration reductions, and overall risk reductions of orders of magnitude, which is ultimately the purpose of remediation.

 

Won’t we have to come back later to remediate the captured PFAS?

I actually suspected this question would come up or something like it and so I’ve got a slide prepared. Is in-situ retention remediation? Well the first thing to say is that according to the US EPA Superfund definition of remediation we’ve already remediated the plume by containing it so it is a remediation.

The PFAS haven’t gone but the exposure potential has been addressed and so the remediation. Will we have to come back later? Well presumably not if there’s no risk driving us to do so.

I’ve already argued against bringing the PFAS above ground but if in future a silver bullet in situ remediation technology for PFAS is developed as Chuck Newell and GSI have called it then we now have PFAS corralled in a focused zone rather than dispersed through a wide area.

You could what we’ve created is a silver bullet shooting gallery and I’m sure that would be helpful if any suitable in-city destructive technology was ever developed. We’d know where the PFAS was and the area will be focused and I believe more accessible.

But the main point is remediation is containment and if the risk is not there then why do you want to spend money or effort going back?

 

You mostly talked about PFOS and PFOA. What about shorter chain PFAS species?

Well, shorter chain PFAS will absorb too, but you generally need more carbon to get the same reduction because their isotherms are weaker. But in many cases, the target cleanup concentrations for these is higher than for the longer chain species.

And in practice, they’ve seldom been a limiting factor for a project. But that said, we’ve had C4 PFAS as specified targets alongside longer chain species. And they’ve had shared reduction targets.

And these targets have been met. One example is a West Coast NatFact project on a circular site installed in 2023, which included C4 species, and I expect that will be formally published soon.

It was successful. The application was back three years ago. It’s still looking good.

 

What about fractured rock geologies?

We’ve done a few and we’ve had success, but the answer really comes down to site specifics and the quality of the conceptual site model, the delineation, how well do we know the fractures and so forth.

There’s a Pennsylvania PFAS bedrock case study on our website, for example, where the PFAS target concentrations were reduced by three nines, 99.9%. The application was through wells and was to a depth of 87 feet below surface.

Also, I believe Rick McGregor and Leticia Benevenuto included a bedrock example, a bedrock application and performance evaluation of plume stop and PFAS in a 2021 paper they published in Remediation Journal.

I can’t remember the formal reference now, but if you write to me again, I can send you a link. It’s open source.

 

Your example showed savings of 60% or so. Is the difference always going to be that large?

Actually, the examples I gave were from relatively high-flux sites. And the comparisons were deliberately conservative. So the cost difference would, in fact, be greater on most sites rather than less. So 60% is kind of the smallest difference you’re going to get.

The difference is likely to be bigger on most sites. And this was shown in the Wurtsmith Air Force base data, for example, where a second phase of the CAC and pump-and-treat installations was implemented where the PFAS flux was about 73% lower.

At this point, the CAC was not 60% lower, it was about 80% lower. In other words, it was about 20% of the cost of the pump and treat at the 30-year point. It was about $1.4 million versus $7 million at the lower flux. So the examples I gave were quite conservative.

 

Could you elaborate on your point about barriers and grids having different dose responses?

Sure. The point I made was that grid treatments and barrier treatments respond differently to the quantity of CAC that’s applied.

Grid treatment will be a whole plume application or a source area treatment, for example, where a grid of points is installed throughout the target area as opposed to a barrier which would be installed as a line across the plume to intercept affecting flux.

In a grid, the whole target area is treated at once and the contaminant concentrations drop as the new equilibrium is established. In modeling terms, this is due to the Kd being increased. The more CAC is added, the higher the Kd and the lower the equilibrium concentration.

So concentration is the dose dependent response. In a barrier, it’s a little different. The CAC dose influences how long the barrier will last for a given incoming contaminant flux. In modeling terms again, the CAC dose influences the retardation factor.

The more CAC is added, the greater the retardation factor and the longer the barrier will last. For a installed barrier and the constant input flux, the groundwater coming out of a barrier is clean until eventually the plume breaks through.

The question therefore isn’t how clean, it’s how long.

And so longevity is the principal dose-dependent response for a barrier.

You do sometimes see different concentrations downgraded to a barrier, but in many cases these are a barrier and what are the matrix effects downgradient as the clean water reaches them and maybe partially recontaminated by mass that’s already downgradient.

 

Could you explain again why PFOA declines faster than PFOS in a pump and treat system?

Yes it’s basically about the different proportions of mass in the phase relative to the dissolved phase for the two species, different KOC values in other words. The salt mass acts as a reservoir and this is proportionally bigger for PFOS than PFOA because PFOS has the higher KOC.

So to understand how this works and simplifying a little, first imagine all the contamination is in the dissolved phase. If you remove one pore volume, you’ve removed all the contamination.

Now imagine 95 percent of the contaminant mass is partitioned onto the solids. Remove one pore volume and you’ve only removed 5% of the mass.

The sorbed mass equilibrates back into the groundwater and you’re soon almost back to where you started so you have to keep pumping.

The bigger the sorb reservoir the smaller the incremental reduction with each volume of groundwater removed and the slower the concentration declines and so this is why the PFOS cleanup is slower than PFOA because PFOS has a proportionally larger sorb reservoir.

The sorbed phase is, of course, only one storage compartment. There are others, too, like the low-K units. But they’re not necessarily as different for PFOS and PFOA.

And that’s perhaps the difference that I showed in the slides earlier. It was not as great as the KOC difference in the example that I showed. KOC is only one part of the story.

 

Are your liability points realistic? 

The liability points are entirely realistic. The legal position is clear and the EPA guidance is too.

I made the point in my talk that documented precedents exist for a wide variety of releases from ex-situ waste treatment and handling and so the potential for fugitive releases is therefore objectively foreseeable.

It would therefore be reasonable to expect legal heat if your company or your client acting on your advice had sent concentrated PFAS waste to a facility that was later found to be leaking PFAS into, say, a township’s water supply or up into the air and impacting a downwind population.

This is the 2020s, so the records are all there. The law is clear on who would be on the hook for this, and the EPA guidance is too. Genuine contributions or not, I suspect even defending against allegations could be expensive. I also think it’s worth restating that widespread practice doesn’t make the liability go away.

Many conventional plumes we’re cleaning up now, for example, arose from what was widespread practice in the past.

So yes, I do believe the liability points are realistic and that to dismiss them would, in my opinion, be no more than wishful thinking.

 

You had a slide, I think, that showed there are lots of sites in the evaluation phase or the design review phase. So which types of sites do you see that go forward with the colloidal activated carbon treatment that you’re describing?

Well, I don’t think there is any specific sites from an industry sector which aren’t going forward. We see a lot of airport sites, we see military sites, we see industrial sites, and so forth. So a whole range of sites are going forward.

If the question, and I’d also state that I’m not aware of any or geographies where the proposals have been put in and they have not been able to go forward when all of the questions have been answered.

If the question is more about what type of sites are not treatable, I think that I’d probably point to very high concentration sites where you may have no large amounts of the equivalent of free product to PFAS, they’d probably be a challenge. And it may be that there’s other things that need to be done first or simply use an awful lot more carbon.

We have a source stop project that we use in source areas to reduce high concentrations, for example. But I think for groundwater, so long as the characterization is good and access is half reasonable, then the treatment should be considered.

If you have a site in mind and you’re not sure about it, I would recommend reaching out to Regenesis. If it’s not treatable, we’ll soon tell you because we don’t want to have sites that aren’t working. It’s a waste of our time. It’s a waste of your time. And we like to see projects succeed.

So reach out to us and we’ll give you a level assessment of its feasibility and we’ll complete a formal design for you if you so wish.

 

What have you seen in terms of what the regulatory community thinks of this approach and has it been accepted by regulators?

Well, I think the geography slide that I shared kind of answers that objectively.

We’re in countries, that’s nine countries with different regulatory regimens and different regulators and different levels of stringency and across the states.

I don’t know how many states we’re in but a good number of states again different states have different regulatory perspectives and different levels of questions that we’ve been asked but there have been no examples of where there’s been flat refusal to use the technology.

We get a range of questions, some of them we’ve heard again at the end of this webinar, and we generally get a good deal of interest, but carbon is used for PFAS remediation, exit you with a pump and treat, sorption onto activated carbon is well known.

So really there’s very little mystery about the technology. It’s simply a matter of ensuring that the designs are done properly, the application is credible and the project is being progressed professionally and that’s absolutely what we aspire to do.

 

You talked about pump-and-treat systems and comparing colloidal activated carbon to pump-and- treat. So do you ever see a site where it’s a combination of pump-and-treat and colloidal activated carbon or in such a case can a pump and treat system be shut down using this colloidal activated carbon approach?

Well, clearly it could be. We saw on the Wurtsmith example and the formal paper that I had the pleasure of working with John Wilson on that even with a high flux site the colloidal activated carbon approach was going to be a good deal cheaper and that a good deal of the money that was saved was from the operational expense of the pump and treat system.

And so using that site as an example, yes, there can clearly be an equivalent remediation put in with a CAC barrier. And yes, moving forward, the costs of operation and the associated risks are going to be eliminated.

So it would be entirely possible to make that if it was so desired. There are a lot of pump and treat systems which start to become asymptotic and at the point that the concentrations aren’t getting any lower, then looking at an approach that can deal with those concentrations in a more efficient manner is clearly going to be something worth considering. I trust that answers the question.

Today’s webinar is titled, Institute Colloidal Activated Carbon for PFAS Remediation in Groundwater, Perspectives from the First Decade.

With that, I’d like to introduce our presenter for today. We are pleased to have with us Dr.

Jeremy Birnstingl, Vice President of Environmental Technology at Regenesis.

Dr. Birnstingl serves as a senior Regenesis technical resource on key remediation projects involving advanced in situ technologies worldwide.

He is the author of the PlumeForce software used for design and modeling of the Regenesis activated carbon based technologies.

Dr. Birnstingl received a bachelor’s of science in environmental biology from the University of Essex and a PhD in environmental chemistry from the University of Lancaster.

He is a fellow of the Royal Society of Chemistry in the United Kingdom and a chartered environmentalist.

He has 36 years experience in the commercial and academic environmental sectors, including 23 years with Regenesis.

His creative and scientific insights have been recognized through three commercial patents.

All right, That concludes our introduction.

So now I will hand things over to Dr. Jeremy Birnstingl to get us started.

 

Very good. Thank you, Dane.

So the perspective I’m going to bring to this talk is that of a technology developer and provider of colloidal activated carbon, or CAC, for in-city remediation.

The perspective draws from 10 years’ experience in PFAS project design, application, and performance reviewing of over 60 projects now the ground around the world and many more evaluated for practicability or the design or pre-implementation stages.

For context PFAS remediation is a subset of a larger body of commercial CAC applications which include the treatment of conventional contaminants such as hydrocarbons and chlorinated solvents. These are on some 600 sites now in 15 countries around the world and date back to 2014 when CAC was first commercially launched as a remediation approach.

PFAS, of course, are a relatively new concern, and this is reflected in the numbers.

Over the 10-year period since the first use of CAC for PFAS remediation, it’s been used for PFAS treatment in groundwater on some 64 sites in nine countries.

So I’ll start this talk with a concise overview the CAC technology and share some key statistics on applications to date.

I’m then going to focus on a question that’s receiving growing attention in the literature and on the conference circuit which is the debate on whether PFAS should be retained in the subsurface or removed for ex situ treatment and I will present three arguments in favor of in situ retention.

So let’s look at technology.

The first commercial CAC product for groundwater remediation was PlumeStop from Regenesis in 2014.

This currently represents the majority of CAC projects.

PlumeStop is a liquid containing tiny activated carbon particles about a micron in diameter.

A proprietary carrier fluid prevents clumping and supports injectability and distribution efficiency.

In simple terms can think of it as an activated carbon ink. It flows but it sticks.

The carbon coating on soil particles is micron thin and doesn’t interfere with groundwater flow.

Plume stop is used to break the pathway of the source pathway receptor pollutant linkage.

It’s injected as a liquid into plume and carbon particles attached to the soil as a thin coating.

Overlapping injections form a capture barrier.

Groundwater continues to flow freely through the barrier but contaminants are stripped out by the carbon. The contaminant migration is stopped, plume and stop, the pathway is broken, downgradient receptors are protected and remediation is secured.

A single application can last many years. If the source remains ongoing, the barrier can be repainted and the clock restarts. Statistics.

To date, there have been some 64 completed plume stop applications for PFAS remediation in groundwater, with about three times this number presently in the final design stages. Applications span nine countries and multiple regulatory jurisdictions.

Applications. The first application of CAC for PFAS was 10 years ago.

Half the present projects have been installed since 2022. Target PFAS species range from C4 to C10 chain lengths.

Median starting concentrations are in the nanogram per litre range.

The upper quartile is in the microgram per litre range and some field applications are now exploring the milligram per litre range.

The highest groundwater velocity treated to date is over a thousand feet per year on a large Swedish site. The highest recorded flux is 21.6 milligrams per meter squared per day at a Californian site, while a recent experimental installation in Florida exceeds 100 milligrams per meter squared per day, although performance data are awaited.

Barrier length ranges from 30 pilots to over 1600 feet up in Michigan. That’s half a kilometer.

The current maximum depth is 150 feet at a military site in Massachusetts. This envelope continues expanding as limits are tested.

How are these performing?

Well, this analysis is from a recent publication by Newell and others coming out of the SADA PSTC program, extended with a few more sites. Data are from a range of projects installed between 2016 and 2025.

The numbers you can see here represent ranked values in each category, so the maximum concentrations before and after treatment, for example, the maximum concentrations before and after treatment aren’t necessarily from the same site.

To me, there are three interesting points in these data.

The first, of course, is that multiple orders of magnitude reductions are common, three to five nines at the top end.

Secondly, there is a skew artefact at the lower end, where after-treatment PFAS concentrations are reported as method quantitation limits. True reductions may be greater, but aren’t reported as such.

Third, the after-treatment concentration range is narrower than pre-treatment.

The difference between the highest and lowest pre-treatment concentrations is about five orders of magnitude, compared to only three orders of magnitude from the highest to the lowest post-treatment.

Now, this partly reflects NQL reporting, of course, but also, I think, is because in properly CAC barriers, the principal dose response variable is longevity, time before breakthrough, rather than the exit concentration.

So this last point is important and easily overlooked, so I’ll restate it. The principal dose response variables differ between barrier and grid treatments.

In a source or a grid treatment, CAC quantity principally influences the post-treatment equilibrium concentration. This is analogous to a laboratory batch study. In a barrier treatment, CAC quantity influences longevity or time to breakthrough. This is analogous to a column study.

The tighter bunching of after-treatment concentrations we saw in the performance analysis is consistent with this. So if Longevity is the principal variable for a cat barrier.

What might we expect? Well, let’s take a look. Because the technology is still too new for actual field data, its longevity must be estimated through calculation and modeling. Longevity estimation was the principal theme of this paper from which the preceding table was also taken.

Analysis of 17 field sites installed between 2016 and 2023 yields projected longevity from 4 to over 100 ,000 years. The median longevity values for PFOS, PFOA and PFHXS are 870, 150 and 180 years respectively.

For perspective, 150 years ago was around the American Civil War. This is the shortest median projection. And 870 years ago was three centuries before Columbus.

But the PFAS stay in the ground. Isn’t it better to remove them? Well, this brings me to the second half of my talk, the relative merits of remediation through in situ retention versus removal for ex situ treatment. I’ll offer three arguments for the case of in situ retention.

These arguments are practicality, cost, and liability. First, practicality. This comes down to feasibility and time.

Pump and treat can clearly remove PFAS mass from an aquifer. But can we realistically remove enough for it to be considered clean?

And how long would this take? My first argument is by analogy.

How many aquifers have we freed from solvent contamination and would we expect the task to be easier or harder for PFAS?

In 2013, the National Research Council assessed that over 126 ,000 US sites had residual contamination preventing closure, stating MCL-level restoration would be unachievable for many within 50 to 100 years. I believe we can anticipate a greater challenge for PFAS.

Our remediation toolkit is smaller, and cleanup targets are more challenging. Stronger natural aquifer retention also means dissolved phase mass will be just the tip of a much larger iceberg.

Hidden PFAS mass on the solved phase creates a reservoir that may slow the rate of plume decline as mass is extracted.

It’s the evidence of this slowdown in practice. These graphs are from a 2024 paper reporting performance of a pump and treat system at the former Birdsmith Air Force Base in Michigan.

We’re looking at PFOS and PFOA concentrations in combined extraction water over the first six years of operation. The central line is the regression of best fit. Upper and lower bands are 80% confidence intervals.

The statistical probability of the regression being outside these bands is therefore 10% in either direction. This table reports the extrapolation of the regression.

We see minimum, mean and maximum time to target for PFOS and PFOA. The highlighted row shows projected time for PFOS to reach the 4 nanogram per litre target. PFOA may reach the target earlier, but the system must keep running until PFOS complies also.

The chance of this occurring within 150 years is under 10%, even before considering that the extrapolations are trend lines, not maxima, and multiple rounds of compliance may be required for closure.

This extrapolation is of course too extreme to have any real predictive value in a numeric sense but we can still conclude that centuries may be required for this system to achieve cleanup.

But I believe these data may be telling us more than just time to target. Why is PFOA declining faster than PFOS despite extraction from the same aquifer in the same water by the same system?

My suspicion is that this is a consequence of the relative retention of the two species on the aquifer solids. This makes the salt reservoir greater for PFOS than PFOA.

Each volume of water removed by the pump and treat system contains a smaller proportion of the overall PFAS mass than PFOA mass, and therefore the incremental decline is slower. The relative kinetics broadly correlate with respective KOC values, and this is consistent with decline rates being limited by re-equilibration of salt mass.

The relevance of this to the present argument is again through comparison with familiar contaminants. If PFOS declines much slower than PFOA, how much slower might PFOS removal be compared to TCE, for example, given the KOC differential between PFOS and TCE is a factor not of 5, but of 21.

Even PFOA has reported KOC values four times higher than TCE. This would suggest PFAS removal by extraction to be much more challenging than TCE, for which our track record is already poor.

Let’s look at the cost arguments, both financial and resource. This graph compares costs of an installed pump and treat system and a hypothetical CAC barrier at the Wurtsmith site over a projected 100-year period.

The red line is pump and treat and the green line is the CAC barrier. Costs are adjusted for discounted present value so incremental costs decline over time. The cost difference is considerable.

Pump and treat costs more than double the CAC alternative throughout most of the projection. This bar chart compares the 30 year point.

CAC is on the left, pump and treat is on the right. Dark blue is capital expenditure, green is operational expense. The CAC barrier is entirely passive with no operational expense beyond the monitoring common to both approaches. The pump and treat system accrues maintenance, waste disposal, and energy costs continually.

The CAC cumulative cost is 7.2 million compared to 19 million for pump and treat at the 30-year point, making the CAC cost 62% lower. CAPEX is about the same for both in this example, so the principal saving is the OPEX.

How representative is this comparison? This is an analogous study at a UK airport by Mallet and others. At Wurtsmith, pump and treat is installed and the CAC barrier costs are calculated.

For this site, it’s the other way round. CAC is installed, and the pump-and-treat alternatives are calculated. The similarity is immediately evident, although the studies were independent.

For the UK airport, two different treatment options were considered for the pump-and-treat system. Granular activated carbon is coloured orange on the graph, and foam fractionation is coloured dark blue.

The CAC barrier cost is 60-65% lower than pump-and-treat costs. At Wurtsmith, CAC is 62% lower. This chart from Kristin Thorson and others presents relative greenhouse gas emissions from the same UK airport study.

CAC is on the left of each graph, Pump and Treat is on the right, and the difference is stark.

CAC projected emissions are 98% lower than Pump and Treat over the nominal 15-year analysis, principally because Pump and Treat had high recurring operation and maintenance, GAC replacement and waste costs.

Error bars show sensitivity analysis for different GAC usage rates. The corresponding GAC analysis is shown but is indistinguishable from the axis. This chart presents the output of a structured sustainability assessment for the same site conducted by Ramboll.

The process considered 15 indicators across environment, economy, and society, each with domain weight, indicator weight, and performance score. A panel of three Ramble practitioners scored indicators using life cycle assessment outputs and qualitative inputs.

CAC scores 84 out of a maximum of 100 versus 43 for pump and treat, with clear advantages in each domain. The CAC score for environment was in fact the highest category score attainable.

Finally, liability.

How might the alternatives impact this? Will they reduce liability or expand it? PFAS extracted from the subsurface become wastes.

The PFAS wastes require treatment or disposal. This introduces the potential for unintentional, unforeseen, or accidental releases.

These may carry significant liabilities. Meanwhile, as we’ve seen in earlier slides, the original subsurface liability may still persist. In this paper, the authors document fugitive PFAS releases from a range of waste handling, treatment, and disposal activities.

Arrows illustrate PFAS movements during such activities. The illustrated releases to air, soil, surface water and groundwater are based on literature examples.

PFAS waste may pass through different stages and releases may occur at any point. For example, PFAS have been detected in incinerator off gases, in incinerator ash and even in landfill leachate from incinerator ash monophils.

Another publication has reported PFAS in landfill off gases with off gas venting or flaring being a legal requirement. These releases have the potential to spread PFAS to other environmental compartments and to expose new receptors.

But waste for pump and treat systems has been handled for years. So is this anything new? Well, it is new for PFAS and PFAS differ from familiar groundwater contaminants in two important ways. They don’t attenuate or biodegrade like conventional organics and problem concentrations are perhaps a thousand times lower and we’re dealing here with concentrated wastes.

Importantly the difference between extractive and in situ CAG barriers do not.

The 2024 designation of PFOS and PFOA as hazardous substances under CERCLA introduced new implications relating to stewardship and liability.

Under this, fugitive releases take on a new significance. The liabilities are both strict and joint and several. Well, what does this mean? A strict liability means that intent to break the law is not a prerequisite for prosecution.

This means that the best intentions that we all share are no protection. We may follow accepted practice with good intent and in good company, but still be held liable and have to pick up the tab.

The liability is binary, not quantitative. Simply contributing some of the PFAS can land a party with the entire liability.

Joint and several means any or all contributors may be held liable and one party being prosecuted, whether successfully or not, doesn’t mean others won’t be at any present or future date.

Not just disposal facilities, not just originators, anyone in the chain, even transporters. Furthermore, anyone potentially responsible party may be held liable for the full cleanup of the site, for impacted natural resources, and more.

Costs could be huge, so we could anticipate the EPA or other prosecutor aggressively pursuing anyone they think can pay. These are scary scenarios. Will they happen? Well, who can say? We’re only just starting. The track record is still to be written but documented precedents for unintentional PFAS releases from waste handling exist.

The release potential might be low but with each operation year the possibility that a release will have occurred will grow.

Over the century projection we considered earlier for example even a once in a hundred years event becomes a certainty. And so to The first use of CAC for PFAS remediation was Plumestop now a decade ago. Since that first site in Canada, it has since been used on over 60 sites in nine countries over four continents representing a range of application geologists and regulatory jurisdictions.

The projects range from pilot sites to large full scale applications. Orders of magnitude concentration reductions of PFAS are widely achieved. Third-party projections of longevity are typically in the range of decades to centuries. Institute CAC treatment of PFAS plumes in groundwater brings no contaminated material above ground.

I’ve offered three arguments in favour of PFAS remediation through retention place over removal. These are practicality. Is it realistically possible to free an aquifer of PFAS and if we can’t remove all the contamination what’s the benefit of removing some of it?

The aquifer remains contaminated. Cost. PFAS can be retained in place for a fraction of the financial and environmental costs meaning more plumes could be remediated for the same outlay and liability.

Bringing PFAS waste above ground may introduce new exposure pathways and expand liabilities rather than reduce them. And with those thoughts, I’ll finish.

So thank you very much.

All right, thank you very much, Jeremy.