PFAS Perspectives: Lessons Learned from a Decade of Experience

Jack: Okay, Dane, thank you. And again, sorry, everybody for the difficulties here today. Challenging times right now for sure. Thank you also to Regenesis for hosting this webinar today and certainly the very timely topic of PFAS.

And then, it’s good that Karen and I can be here. We’re fortunate to work for a firm that has been involved with PFAS risk management and sampling for over a decade now. So we have access to a considerable number of sample results from all sorts of different media and to an extensive library of PFAS information. So from our standpoint, PFAS has been an exciting topic for a number of years. We’re happy to be able to be here with you today and share that. And again, Dane pointed out so many of you are working from your home or in limited groups at your offices. So hopefully there’ll be a little something in the webinar today that will fit for each and every one of you.

So Karen, next slide, please.

So perhaps your introduction to PFAS came through a newspaper article, a TV presentation of some PFAS issue, a law review, some sort of an online resource. Perhaps even you’ve seen the documentary on Netflix, The Devil We Know, or the recently released movie called Dark Waters, or have even read the book by the attorney Rob Bilott called “Exposure.” All those things will give you perspective on PFAS, and to some degree, there’s been a fair amount of hype and even levels of hysteria, and perhaps some of that’s warranted, given that PFAS has impacted a number of drinking water supplies across the country.

So we know that PFAS is a big issue, but it probably means something a little bit different to each and every one of you. Next slide please.

Perhaps some of you are eating you familiar with the large legal settlements that have been broadcast out there, the 3M settlement in Minnesota, the Dupont settlement through West Virginia, and those are in the hundreds of millions of dollars. And yet there are still numerous legal actions that are taking place to this very day against various industrial entities. And so that goes on. And that’s something that’s going to continue on into the future.

And if you look to the right of your screen right now, you will see our recent tally of PFAS sites that exist across the US. Now a number of those are military installations or airports or fire training academies, but there are a few industrial sites that are sprinkled in there along with landfills and even a couple of car washes. So there are unique sort of circumstances to under which PFAS presents itself, but that’s our most recent tally. And as any of us that are involved in the PFAS world know, that will quickly change. So next slide, please.

So our agenda for today, I’m going to assume that the vast majority of you have been like me, where you’ve stood in the back of the room at a standing room only PFAS session at a conference, or you’ve been to a recent workshop on PFAS. So we’re going to go fairly light on the PFAS basics, I will make it a point to touch on sampling and analysis and remediation briefly, and I’m going to talk to you about what you can tell from a safety data sheet, an SDS, and believe me, there’s more in that then you might appreciate.

And then we’re going to move on to Karen and she’s going to talk about a unique sampling case study. And then we’re going to get into our way to look at your PFAS data and some patterns that may emerge. That’ll be interesting for you to recognize. And then, as a bonus to this webinar, we’re going to finish up with Regenesis and Dr. Kristen Thorson, who will talk about the actual performance of PlumeStop at a PFAS remediation site in Michigan. So that’s how we’ll finish up today. Next slide, please.

So we’re gonna start off with PFAS Basics. And again, I’ll go light on this, since I believe most of you have knowledge in this area, but we’re going to talk about the what, the why, and the how very quickly. So next slide.

So PFAS, the acronym stands for Per- and Poly- fluoroalkyl Substances. And we mostly talk about the Perfluoroalkyl substances which are featured to the right of the tree and you’ll see the cursor moving around on that now. The most notable of those would be PFOS and PFOA. We have a good amount of information on those particular PFAS compounds. And a lot of toxicology information on them.

Now we’re gaining information on many other Perfluoroalkyl substances, but it’s going to take time to accumulate all that and we are going to get more knowledgeable but there’s a certain time element associated with it.

To the left top portion of the tree, you’re going to see the Polyfluoroalkyl substances. And an example of that would be fluorotelomer alcohols, which in other words, are precursors. Precursors are fluoro compounds that have a tail on them that is oxidizable and biodegradable. That little tail can be acted upon through oxidation, biodegradation and converted or transformed to a Perfluoroalkyl compound. You can never increase the number of carbons when you make that transformation, but you can decrease the number of carbons, so you can go from a C10 compound to a C8 compound, but you cannot go from a C10 to a C12.

So it’s possible you could have a polyfluoroalkyl substance and have a transformation take place and wind up with PFOA, that’s certainly important. And we talk in terms of these compounds as short chain and long chain, most typically refer to long chain as those with eight carbons and above, short chain typically C7, C6 and below. And those are very, very important as we hear a lot nowadays about materials that have short chain PFAS or even that are PFAS free. And those designations are very, very important. Next slide please.

So what is PFAS? PFAS are man-made chemicals. At most recent tally, we’re in the neighborhood of about 5000 compounds, we know that they’re very, very stable in the environment, which means they persist. They bio magnify, they bio accumulate. So nearly each and every one of us on this call right now has some concentration of PFAS in our bloodstream, and that stays in our bodies for years at a time before it’s removed from the body. So, PFAS has a specific resiliency.

And then of course we have the carbon fluorine bond that is characteristic of this class of compounds and it takes a tremendous amount of energy to break that bond, which complicates PFAS remediation, takes a lot energy again to break that bond. It’s one of the strongest bonds in nature. Next slide, please.

So why do we use PFAS in the first place? Well, the answer lies in its properties. PFAS can impart oil, heat and grease resistance. It has excellent waterproofing properties. It is the best fire retardant on the market. And it provides surfactant properties and longevity, durability, anti-corrosion properties. But probably the two that stand out the most here, the surfactant properties are key because so many products that you can think of either as raw materials, or as actual end products, contain surfactants. And a lot of those surfactants are fluoro surfactants, which contain PFAS.

And then lastly, it’s hard to go away from a material that imparts such good quality properties. So there is a resistance to doing away with AFFF, aqueous film forming foam for fire scenarios because it is so good at what it does. So a lot of the agencies that regulate that are hesitant to move forward with other types of foam materials because they just can’t get the same quality of property. So that’s why we use PFAS. Next slide please.

And this is an example of all the different industries that are touched by PFAS. The fluoro council here has produced this list and within each and every one of those industries there are a number of different uses for PFAS compounds. Again, surfactants play a key role, but they’re also, because they impart so many good properties, find their way into all these different areas and frankly, everyone listening, this list grows all the time, we’re learning about new PFAS sources almost on a weekly basis.

So PFAS is pervasive in our environment. Next slide, please.

And to make things extra interesting with PFAS, PFAS is measured in parts per trillion, or nanograms per liter. For those of us that have been in the environmental industry a long time, you know, we’re used to measuring things in parts per million, or parts per billion, milligrams per liter, micrograms per liter. Well, here we’re talking nanograms per liter.

You know, occasionally if we’re looking at a raw material source or a very concentrated PFAS scenario, we might see percent concentrations, we might even see part per million or part per billion concentrations. Most of the time, we are working in parts per trillion. When you’re working with units that are that small, there’s an awful lot of care that has to come into your sampling and your analysis. So that’s very, very critical, very key distinction for PFAS. Next slide, please.

So important PFAS topics here. Again, I mentioned we’ll touch on sampling, analysis and remediation very briefly. So let’s move on to the next slide.

So sampling, so our lessons learned from all the decades of experience that we have is that PFAS sampling takes careful planning, you just don’t send someone out to the field to collect PFAS samples. The planning component is the most important part because you have to think about the matrix that you’re sampling, the equipment that you’re using, the sample containers that you’re using. And then of course, all the potential for background contamination that may exist within the environment that you’re sampling under, and also the clothing that you’re wearing, the cosmetics that may be on your skin, the bug repellent that may also be on your skin. All those things are important considerations if you’re going to sample at a PFAS impacted site.

Many firms may have their own SOPs, standard operating procedures, for how to sample PFAS, but there are also state guidelines that can be used, and those things have to be married up in order to do the sampling in a proper manner within a particular state.

And then lastly, it’s important to have blanks along with the sampling because blanks will tell you a lot about the environment. We often find in a field blank that we’ll pick up a little bit of PFAS contamination because it is within dust particles that are moving across the area that we’re sampling under. So that’s a very, very important point, to have blanks available as part of your sampling program. Next slide, please.

And of course, the analysis component is critical. Now we, we make it a point to work with laboratories that have experience with PFAS sampling. I know everyone wants to be in the PFAS game now. But it’s important to work with laboratories that have done numerous rounds of samples and have an ability to test different matrices, whether it’s soil, groundwater surface water, sludge, materials, raw materials, all those things to have that versatility. And to be able to have a conversation with the lab up front, because it’s important that the lab understands what matrix you’re sampling, what sort of potential concentrations they might encounter.

It’s also important to work with a laboratory that’s worked through the issues of laboratory contamination before. It’s hard to get rid of PFAS in the air in a laboratory. It takes an effort, it takes time, it takes awareness. And so we tend to gravitate to laboratories that have whipped this issue or can deal with it more effectively.

And lastly, it’s important that any lab report that you get, that you scrutinize the data, and that you go through a good level of data validation. Don’t just take your laboratory results at face value, make sure that data are valid, that someone who’s a solid data validator is looking at that particular scenario and can ensure you that your data is of quality nature.

And again, it’s important that your lab have capacity, right? Number of labs have multiple locations where PFAS is analyzed. It’s important they have capacity to deal with your samples and that you can get a reasonable turnaround time. Next slide please.

So remediation side of things, I know a good deal of the remediation out there has been done on federal sites or on airports or fire training academies. We do have an arsenal of ex situ technologies that are used for PFAS. They’ve been used for a number of years now. They have varying degrees of success. Some are very effective, and maybe have only a couple of PFAS compounds that they struggle with. Some have struggles with different concentrations of PFAS compounds. So as you can see there, there is a decent list of technologies that are available. But of course we want better, faster, cheaper, and that is coming along. And in situ technologies are of great value to us now. You’ll hear later in the webinar a discussion on the PlumeStop technology which now has more than a year of infield data, and that becomes valuable to us.

And there are lots of other technologies that are being looked at right now for subsurface applications. They fall into the categories of oxidation, whether that’s tried and true oxidation with some novel activation mechanisms, or that’s electrochemical oxidation. There’s some plasma technologies now too that are gaining an interest. And there are a number of things that are being looked at that focus in on the breaking of the carbon fluorine bond. And we can expect to hear more on those technologies as we move forward. And then I think those technologies are really just around the corner and really only need a couple of sites to be tested on in order to see their validity. So stay tuned for that, and it’s an evolving area, and I expect we’ll see even more in that area of remediation this year. Next slide, please.

Alright, so my last piece of the webinar right now before we transition is, “What can you tell from an SDS?” A safety data sheet. Seems like a very simple document. So what could you tell if you’re looking at a safety data sheet of a raw material or a finished product and whether or not it contains a PFAS compound? So next slide, please.

So looking at the two boxes on the screen there, the upper box will give you a little tip, right? If you look toward the bottom of the circled area there, it’ll say proprietary fluorosurfactant. That is your tip right there that that is a PFAS containing material. If you look at the box to the bottom, which happens to come from an AFFF product, it’ll say something like the chemical and/or percentage of composition is being withheld as a trade secret or as a proprietary component. That’s what you see more times than not.

Now, will you ever see a safety data sheet say, “This product contains PFOS”? Or PFOA? Well, not so much PFOS. I’ve rarely seen that except for some very, very old Material Safety Data sheets. Once in a while, as we review SDS, we will see PFOA noted. So that’s obviously a dead giveaway right there. There’s PFAS in that particular material. But most of the time, the listing will be very cryptic. You might even have to go down to the section that talks about combustion products and see that it notes fluorinated byproducts produced from combustion. Oh, okay, well, that’s another tip that that’s probably a PFAS containing material.

But most of the time, beyond the SDS, you will have to go back to the products website, and you will have to dig for technical information within that. So it’s a combining of the SDS and that additional research that’s going to help you understand whether a material is PFAS containing. And it might even entail a phone call to the manufacturer to better understand what exactly is in that product.

So there’s one other reason why a safety data sheet is important from a PFAS perspective. Just recently, the National Defense Authorization Act by EPA has created an additional requirement to list 160 PFAS compounds on their Toxics Release Inventory. That’s very, very important because that requires industry to take a tally of what they have on hand as far as PFAS goes and collect data on that PFAS, and they have to report that data by July of 2021. So that’s very, very important. And again, there’s 160 PFAS compounds on that list. So that’s a very, very important aspect of why an SDS is so important and why you might want to know if a particular raw material you have on hand, or a product you make, contains PFAS.

So lots and lots of other little details we can go into regarding the basics of PFAS and we can certainly cover that in other webinars. But for the sake of time, we’re going to move on to our next aspect of the webinar. And, Karen, we’re going to have you take over from here.

Karen: Okay, thank you, Jack. And can everybody hear me all right?

So let’s take a look ahead at what you can expect as regulations continue to evolve. In this case, we’ll cover not only a unique sampling method, but also what we can learn from it.

So how many of you had the opportunity to work on a facility or had a facility where a fire had occurred?

Well, we had, and in this case, in 2016 an explosion and fire occurred resulting in over a million dollars in damages. And that was bad, and these were reasonable unexpected costs, but this is only the beginning with the unexpected costs associated with managing PFAS in stormwater. And this is because the state was in the process of designating PFOA and PFOS as hazardous substances.

So, upon the fire being put out or the state had actually arrived on site and mandated that all storm water in all water firefighting water be contained, storm water drains recovered, and not only contained but contained until that storm water had achieved 70 parts per trillion.

Well, you know, first thought, we looked at this and thought, well, it’s a surfactant and it should just wash away right with rainfall and we’ll just keep collecting it until it dissipates. Well, that’s not exactly what happened. And so I’m asking you, what kind of conclusions can you draw from this graph?

So at the top bar here what you’re looking at is a logarithmic scale of the PFOS concentration in green, and the PFOA in purple and your standard in orange. And this is over a four-month period. It’s not dissipating. And it says to us, even after rigorous cleaning, we still start at 165,000 parts per trillion. And still, after four months, we’re at 10,000 parts per trillion. And you do see a decrease here, but that’s as the temperatures are freezing and we had less rainfall, but as soon as things started to melt again and we had more rainfall, well we had a rebound. Suggests there’s an ongoing source. It’s not depleting fast enough. And we needed a fast-qualitative method to understand the source, and whether this source of stormwater was on the majority of the property, was it off the property? And where the foam, you know, where the foam had landed? We had no knowledge of where the foam had actually touched. There’s no visual other indicators for PFAS, right? There’s no odor associated with it. You can’t see any visual aspects of it.

So projecting out, hey, the cost to contain, transport, and dispose of the stormwater’s tracking out to be greater than $400,000 per year. That’s not sustainable, plus it interferes with operations. So not only was the asphalt already high pressure washed, we’re still seeing these high concentrations. So what and where to sample, it’s a completely impermeable surface we’re looking at. So obviously a hotspot source and extent assessment was needed, the challenge is how do you sample the infrastructure?

So, we came up with a method that was going to mimic the stormwater, right? We needed something qualitative, not quantitative. We needed something that was going to be repeatable. So we wanted to make sure that we always use the same volume of water rinsing and the same surface areas from sample to sample, regardless of whether it was a tank surface, the pavement surface, the chip seal or gravel above the pavement, and soil beneath the pavement.

And actually the state accepted it. And this is a picture of one of our sampling locations for the asphalt. And we noticed that at some locations, there are cracks in the asphalt and that’s where we wanted to take some soil samples. And here’s what we got from the asphalt samples. Here’s a depiction of the site on the right. And we have, you can see there’s really not a smoking gun here. We see some parts per trillion concentrations, we see something maybe a little bit elevated, and that’s just happens to be over on this side. But that’s not our hotspot and that’s definitely not causing these high concentrations in our storm water retention area, which was over here.

This is the direction of the stormwater by the way. And this circle over in red actually represents where the tank fire occurred. So let’s see what we get in our next sampling suite.

Well, okay, here’s a zoomed in area of the tank area. And here’s the actual direction of the application of AFFF we found out later. But select ASTs had 30,000, 20,000 parts per trillion. Well, okay, we found our source area. We now know it didn’t go off site, it was very localized, and we can now set ourselves at ease that this could be addressed, and it didn’t carry very far.

Now look at this AST number five. Hey, we’re now seeing that where the AFFF actually landed was a good indicator where we’d find our hotspot. It didn’t transfer very far via aerosols.

So let’s look ahead at, okay, our soil samples, the pre soil samples before excavation, the remedy that the client selected was removal of the tanks and removal of the infrastructure, removal of the chip seal beneath the tanks and the asphalt beneath the tanks, and then a foot and a half of soil beneath the tanks. And that was just precautionary. Before we did that, we put up a berm to keep stormwater from running into the excavation to make sure that we didn’t contaminate the soils after this material was excavated.

Now in soil when you run these tests, the results are in parts per billion. So we had some detections in the pre samples but they weren’t as elevated as post excavation. This one sample was kind of alarming to us and we had to dig a little deeper here. But how did that get there? There are no cracks in this particular area, and what we are hypothesizing is that during the excavation, the bucket probably dragged down some of the PFAS. And so our resolution now is to decontaminate between the buckets and actually try to do the excavation in lifts.

So here’s the rest of the story. Here’s an extension of the earlier graph of PFOA and PFOS concentrations in stormwater, except it’s stretched over eight months. And now we’re starting to see some action here. Now we’re starting to see some prolonged reductions. And it wasn’t until we actually repaved that area that we actually got down to our target levels. So the client was relieved. They didn’t have to spend another million or so on wastewater for the next year and who knows how long that could have lasted. But it was a success and a value to the client.

So what are our takeaways? Well, here’s some remedial tips. The rinse sampling method was an effective qualitative tool. It was accepted by the state and really got to home in on our hotspot. Our hotspot, what we found, was very localized. And it was basically at the point of application. The hotspot didn’t travel far from its point of application. So the other thing is you have to be very careful about excavating and removal. Soil removal is very easy to drag it down. So you’d want to do that in a surgical manner. One-foot lifts, if that, if possible, half-foot lifts, and then you’d want to decontaminate your bucket between lifts.

Also we use this practice, the stormwater containment berms to prevent stormwater from run-on into the clean excavation. Other things that you can consider is also learn about the AFFF that was used. This case, the fire department didn’t have any records of the AFFF that was used. There was no SDS. But we did get some information as to where they were positioned and how they were pointing and what areas they were focusing on the fire.

We also noticed there was a ratio between PFOA and PFOS and it stayed roughly the same throughout the entire monitoring event. And we kind of see that in a lot of our site investigations. And we though, “Oh, that’s kind of interesting.” But the biggest takeaway here is the rain did not simply wash away the PFAS. It stayed around 10,000 nanograms per liter for months after the AFFF was deployed. It’s, I like to call it, just sticky.

So those ratios in that case study, and others, kinda piqued their interest and we wanted to take a deeper look at that. So that led to further studying for us.

And we dove into our database. We had thousands of samples and we kind of honed it in on 25 sites. And those 25 sites were all AFFF sites for various types of industry. And we decided, well, let’s use some typical plots to see what we get. And there’s what we got. Total chaos, right? This is a common tool used in environmental forensics, but hey, this was not meaningful at all.

We didn’t give up. So we wanted to take a look at, “Okay, what do we know more about these 25 sites?” Well, we looked in and all these sites, we had a survey. We knew what brand of AFFF was used. We knew that nine sites had brand A, seven sites were mixtures of A, B, C, and D. And that wasn’t very helpful. But three had brand B, and that was helpful. So let’s take a little look and see if we can find if any other patterns come up. Well, this is one airport site and no go. There’s not a real good pattern here. So why would that be? There are lots of variables. Geochemical, and these are individual PFAS that all behave differently because they all act differently depending on your pH, your, your, oh, FOC, organic carbon, that’s a very important one.

So we thought, okay, let’s not give up. Let’s dig a little deeper. And we started look at the more stable and frequently detected PFAS. And we chose from this list. Now this list is what was included in our analytical procedures and some of it ran from 4 chain all the way up to 12 chain. But we picked these three sulfinates because they were the most prominent, most frequently detected and PFOA, because we know that to be a very common and it was also in AFFF and it was also highly detected and more frequently.

So what did we get? Wow, hey, we start to see a pattern here. And, you know, the reason why we kept the PFBS in, PFBS was only found in older formulations. It’s not really conducive to use in AFFF because it doesn’t have that film forming property. And that’s this right here, that’s the 4 chain. And it kinda looks like a pattern here. Right? So, the next step was okay, let’s take this brand A AFFF and compare it to other sites with brand A.

Good, okay, we do see some kind of trend here. It’s not a perfect match. What we’re seeing is there’s slight variations from site to site. But these are a great start to looking at what does your site picture look like for these ratios? And what is the meaning of that?

So in comparison we just thought, oh, let’s take a non AFFF site and see what that looks like. And this is all groundwater and there is a pattern even in non AFFF sites. But then, okay, we wanted to see, okay, what does it look like from one site, the sample for more than one media? Just as you expected, because of how PFAS behaves associated with FOC or other variables or other geochemistry, the pattern is not going to hold true.

So that’s one of our lessons here. You can’t use pattern matching across the media.

But in closing, the case study that we started out with, in the stormwater, the pattern did hold true for us and it was very site specific. And it can help tell us something about your AFFF and help identify off site sources from your on-site surface.

So, takeaways from that experiment and study we did, the PFOA, PFOS and the PFHxS and others will stick around infrastructure and will simply not wash away on their own after AFFF application. It takes high energy to remove. The PFOA, PFOS remained roughly the same ratios in groundwater. Although there are precursors and transformations going on. Either they may have already occurred or it’s a very slow process. The ratios, they seem to be very site specific. And there might be some variations between sites even with the same brand. Even with the same brand lot number there are some variations. There are logarithms that are available for PFAS source typing, but understand the assumptions built in before you apply it to your site. No two sites are alike. And no pattern matches or ratios between media and even on the same site even the same brand. And it’s very important to understand your fate in transport to collect such data as your fraction of organic carbon, the pH, the anions and cations and possibly other factors in in the media.

So with that, I’d like to thank you and turn now on over to Kristen Thoreson of Regenesis.

Kristen: All right, great. Thank you, Karen and Jack for joining us today and for sharing that information with us. It’s a lot of good insight from your experiences. I’d like to take the last few minutes of the webinar here to discuss the strategy in the use of PlumeStop colloidal activity carbon to address PFAS in situ. Something we’ve been doing for the last, you know, especially over last year, but even the last few years. So next slide, please.

So the few slides I’ll share are going to cover these bullet points. The first one is really just the strategy of using colloidal activated carbon in situ. And then some key considerations for using colloidal activated carbon and what how you might make a decision to think if this as a possible choice for your site or not. And then we’ll actually go to a field case study and show some of the results at the end of the year. Next slide.

Okay. So the approach we’re taking is in situ sequestration of PFAS to protect sensitive receptors from PFAS. And we’re doing this by injecting a permeable cutoff barrier of colloidal activated carbon. And the approach here really is about removing PFAS from the groundwater in order to prevent further migration and magnification of this problem and to remove it from the groundwater so that we decrease the exposure pathway by preventing it from getting into surface bodies of water or drinking water supplies in order to protect and reduce the risk that we’re exposed to as humans from these various pathways. Next slide, please.

And so the way we can actually do this is using PlumeStop Colloidal Activated Carbon. And if you’re familiar with this product, and even if you’re familiar with other ways of addressing PFAS, you know that activated carbon is something that works to [inaudible 00:38:54] PFAS, and we developed a form of activated carbon that allows us to distribute the activated carbon via the in situ under low pressures. We can use dry push or injection wells to actually inject this into the ground and we’re able to get a permeable barrier in which the PFAS can passively transport through this zone, stick to the activated carbon and the down gradient water gets cleaned up.

The key tell this is the [inaudible 00:39:23] activated carbon. We actually take a traditional activated carbon, melt it down two microns in size, that’s what allows us to inject it widely in the subsurface.

Typically, it’s really hard to get activated carbon in the ground. But by doing this, it makes it possible along with some other additives that keeps it from clumping and from you know, getting stuck right at the injection point. The idea here is that it spreads out in the subsurface and it actually will adhere to this soil particles so that it will not continue to move once it’s injected. Forward, please.

Now I want to be really clear around the mode of action with PFAS and activated carbon. This is true with any activated carbon. This is a dynamic adsorption, which means it’s not a permanent immobilization. This is not going to necessarily last forever, but it can last for a significant amount of time. And the reason for that and really, the way to think about it, is that it’s actually increasing the retardation factor of a PFAS plume much beyond anything that can naturally pair with the natural [inaudible 00:40:25] that’s present in the soil.

So to give you some numbers on that, the natural retardation factor for PFAS, due to the natural [inaudible 00:40:34] of an aquifer is typically on the order of three to 20 times. So I think that’s, the PFAS is moving about three or four times slower than the groundwater. But by being able to inject the colloidal activated carbon in a typical dose, depending on the concentration, of course, and the exact species we’re talking about, we can now increase that retardation factor by orders of magnitude. And what that means is that it’s really contained for decades. That PFAS going to stay in that zone a significant amount of time. Next slide please.

What this looks like is a low-cost option, and that a single application can last for years to decades. Once that application is conducted, there’s no continual operation and maintenance costs beyond continuing to sample wells down gradient. There’s no waste because we’re not pumping anything out of the ground. Now, it is important to realize that yes, at some point, these barriers will fill up and so it could require reapplication at some future point in time. Typically what that would look like is another application down-gradient of the original barrier. If there’s some room there, it could be in a very similar zone to where it was originally placed.

The other idea here is that we are taking a large solute plume and we’re able to localize the contaminant, contain it in a localized area and concentrate it. And as Jeff mentioned at the beginning there’s a lot of work being done on disruptive technologies right now. And so with this in mind, as those developments occur, there’s a possibility that down the road within these zones where we’ve actually trapped and contained the PFAS, we could go back and take one of these to be developed disruptive technologies and actually implement that in that area. And now it’s in a much smaller than if you’d have to do that across the entire plume, or much wider area. Next slide, please.

So some key considerations that we go through and something that you can think about as well, if you think you might have a site that this could make sense for, is first of all, what are the target contaminants of concern? Just like any activated carbon, not all species, absorb with the same affinity. So the longer chain PFAS do absorb more strongly, more readily than the shorter chain. The shorter chains do still absorb but they are going to be required either much more activated carbon, or the longevity is going to be somewhat decreased there. So something to consider.

Really, it all boils down to contaminant flux. So I often get the question, “Well, what is the max concentration of PFAS that you can treat?” And the answer is not that easy, we typically have to take into account both the concentration as well as the groundwater philosophy because it is about flux. You know, there are cases where a little bit higher concentration of PFAS can be treated because it’s moving quite a bit slower. And there are also some cases where it’s actually quite low concentration, but it’s moving really fast. And then that may be a situation where this is not gonna be a viable technology. But these are all things that have to be considered and have to be weighed in on a site by site basis. Forward, please.

The other consideration that’s really important and this is true of any time that we’re using PlumeStop for any type of contaminant. We need to know what other dissolved organic species are present. Whether that’s other contaminants, whether they’re concerned or not, any and other dissolved organic species, because we cannot tell the carbon to only absorb the species that we care about. And so this all has to be taken into account upfront. If there’s any significant demand from something else that’s going to drive what we have to do to design, that’s gonna require more carbon. And it’s something that we can consider and may have to get a little creative how we deal with it. But it’s important to know that up front in order to understand what the potential longevity of the treatment can be. And next slide, or forward, please.

And then the final component is the application. So there’s a lot of care that goes into actually applying this in the ground. As I mentioned, this is a form of activated carbon that is meant to be distributed in the ground. And so we’re really building this underground fence, underground permeable reactive barrier. In order to make sure we don’t have holes in that fence. There’s a lot of work during the application that has to be done, quality control, to ensure that we’re getting that connection between different injection points, whether that’s an indirect push or injection wells. And so as an example, we’ll take a lot of soil borings as we’re doing the injection to make sure that we are getting the distribution and the connection.

There’s also a lot of work that goes on even before we get to the application to understand what the geology, what the nature of the site looks like to make sure we come with the right tools, and the right assumptions to be able to get that into the ground, as needed. Next slide.

And so to give you an idea of how this has been implemented: Today, there have been nine sites where colloidal activated carbon has been used to adjust PFAS, many of these are pilot sites, so to get the first understanding of how it’s working for those particular contaminants at that particular site. And there’s quite a few more pending that we’ll be implementing here over the course of the next year. As you’ll see, I think almost every site we’ve done so far has been a mixture of PFAS along with another commingling contaminant, typically petroleum or chlorinated solvents.

And you can also see that there’s a range of concentrations that we’ve addressed so far. Again, it’s not just about the concentration, it’s about the flux at the end of the day. But the one side I’d like to take a little time to go forward is this US Army Guard Base in Camp Grayling, Michigan. You can go ahead again, one more slide, please.

So the background here on Camp Grayling is a National Guard Training Center, and also is home to the Grayling Army Airfield. And we started working with the Michigan National Guard on this site because they have had various contaminant releases over the years including petroleum, chlorine and some PFAS. Obviously PFAS is the issue that brought us to the table here because the various other remediation strategies weren’t addressing that. So next slide, please.

So we went to come up with a pilot test and this is in a portable storage tanks area. You can see in the contamination levels there, it’s a mixture of PCE along with PFOS and PFHxS. And it’s fairly low levels of the PFAS, in that kind of 100, 150 parts per trillion level. That’s really going to be a good scenario, the site is not moving incredibly fast. So again, when we think about the flux, it’s in a reasonable range, where it’s going to be effective.

And the strategy here was, again, in the pilot test to implement a cut off barrier. In this case, direct push was used to inject the colloidal activated carbon, those points in that arc are the direct push injection points.

And if you see there’s a couple blue dots on that, there’s a blue dot up gradient of that barrier, and there’s a blue dot down gradient. So those are the monitoring wells and I really like the orientation of the setup. This is something that we worked with them on because we have that up gradient control well that’s going to make sure that we can monitor what is coming into that barrier, if anything has changed, again, we can look for any other organic species that come in that might change how the barrier is performing. And then obviously, we have the down gradient wells to monitor the actual performance over time. So next slide, please.

So first, the data I have shown here is just the up gradient well, and so these are the concentrations coming into that barrier. And we just have the one-year data point recently, so you can see that the concentrations have stayed pretty consistent, moving from the up-gradient source and into this barrier. So no real changes there, no surprises coming through. Go forward one more.

This is the data from the down gradient wells of the PlumeStop area. And this is pretty typical. This is what we would expect to see when the application has been successfully applied, when we have good distribution within about one to three months here, we saw the concentrations decrease in all those down gradient wells. And as you can see, over the course of the year, they have stayed at a non tech level.

Again, this was a pilot test, and so this was implemented to understand that this was going to be a viable option here. We’re going to continue monitoring, and then there are plans to go full scale in the next couple of years. Next slide, please.

So to wrap up, I like that example of the use of PlumeStop to address PFAS at Camp Grayling. It’s really demonstrating this idea that we have a flexible, low cost in situ option to address PFAS to really have this passive plume control and containment. In this case, we were cutting out that barrier from getting into a neighborhood. We’re preventing the expansion of the problem. And in doing all of this we’re removing the PFAS from the dissolve phase from the groundwater, and again, that’s helping to manage the risk, to reduce that exposure pathway.

So we’re going to continue monitoring these sites. I didn’t get a chance to mention, we have actually one other site in Canada that has four years of data from a single application has been working. There’s a lot of information on our website, if you want to look into that one. That’s the longest running site we have. And we have more sites that have been implemented, we’re continuing to collect data. And we’ll have more to present on that in the coming months and years. So with that I’ll turn it back over to Dane and I think he’ll open this up for Q&A.

Dane: Yes, thank you very much, Kristen. So yeah, that concludes the formal section of this presentation. Again, we apologize for the audio issues at the beginning. This caused us to go over a little bit. So we are over our hour, and usually we cut it off at exactly an hour, but we’re going to go over a little bit, so we get into some more your questions. So with that, let’s circle back to the questions here. The first question, this is one for Karen, and it is are there facilities that will dispose of or incinerate PFAS waste.

Karen: Yes. First of all, PFAS waste management is a bit behind in the regulations. There are facilities and I have a list of them, and I can’t name them off, but for water, there is carbon treatment and ion exchange are the two proven methods and then for solids it’s incineration or landfilling. And you want to make sure that, if you’re going the landfill route, you want to make sure that you’re going to align landfill, really inspect that landfill and make sure you’re protected from future liabilities. But for incineration, there are some facilities that are operating but there are some potential bans out there for incineration. Certainly there are a few communities that have issues with enough quality controls to make sure that the incinerators are operating at the optimal temperatures, and they feel the communities feel safe that what’s coming out in the atmosphere is not causing any harm.

Dane: All right, thank you very much, Karen. So here’s the next question. Also for you, Karen is from a PFAS regulatory standpoint. What are the most active states right now?

Karen: Oh, okay. Well that’s a big question. Actually, there are 29 active states. And the best way to look that up is to type in ‘safe states and PFAS’ and you’ll get a map of the states, but the majority of them are in the northeast. And then a number of them are in the western states. Certainly, and then you’ve got the Michigan, Wisconsin, Indiana, Minnesota and Iowa but there’s a whole bunch of them in the north east, all the way down to Florida. And then your Washington, Oregon, California are very active.

Dane: Okay, all right, thanks. So here’s another question. This is a question for Jack. And it is, “I heard most PFAS are non-volatile. So, how do they get into the air and can we analyze them in air?”

Jack: That’s an excellent question. And most PFAS are non-volatile. There’s probably some exceptions hidden within that massive list. But typically what we find with PFAS is that the PFAS compounds adhere themselves to dust particles and travel through the air. We’ve seen sites where at the exit point of a scrubbing unit at an industrial facility, at that exit point, you can sometimes find PFAS concentrated because it’s come through with dust particles and it accumulates there. Yeah, as far as analysis goes, we’ve seen people try to analyze an accumulation of dust, wash the dust and try to analyze PFAS. But the only place we’ve actually seen a vapor method for PFAS is in Europe. If there’s one available here in the US, I’d like to hear about it. But the only place we’ve been able to find that so far is in Europe.

Dane: Okay, thank you very much, Jack. So here’s a question for Kristen. And it is regarding the case study, the Camp Grayling case study. Or I’m sorry no, this is a more generic one. Do you use a water [inaudible 00:54:41] to push the PlumeStop out into the surrounding areas?

Kristen: There are definitely different strategies for how to get PlumeStop into the ground. The most common way is that we are, you know, PlumeStop is delivered to the site as a concentrate, does get diluted with water before it gets injected. There is going to be some chase water [inaudible 00:55:06] afterwards, there can be different reasons for doing more or less chase water. But we’ll use just at least a little bit to push out some, but typically the design is that that total volume of PlumeStop trying to get it to where it needs to be. But, yeah, well we’ll look at each site on a case by case basis to make sure that we can get that distribution where it needs to be.

Dane: Okay, thanks, Kristen. So here’s a question for Karen it is, “What is a chips seal sample?

Karen: Well, a chip seal basically is what the owner was calling the gravel underneath their tanks, and the chip seal is a bit smaller than gravel. And so we had to calculate the surface area of that gravel. Too big of something to send in for a soil sample, but certainly we wanted to apply the rinse sampling. So what we used is a colander and put in the amount of chip seal that would equate to the same surface area of other surfaces. And so to answer your question, it is basically a smaller grain sized gravel.

Dane: Okay, thank you, Karen. So, Kristen, here’s another question for you. And this one is regarding the Camp Grayling case study. It’s “Did you find generation of short chain PFAS compounds down gradient of the barrier?”

Kristen: So downgrade of the barrier, the detections have all been [inaudible 00:56:42]. So we don’t have any new formation of anything that I’m aware of. Also, this particular site has very limited different total species going into that [inaudible 00:56:55] as well. Again, it’s from really PFOS or PFHxS or the yearly predominant, and maybe just a trace of one or two other components going into that, but we’re not seeing any other products down gradient.

Dane: All right, makes good sense. So here’s another question for Karen. And the question is how do you decontaminate the bucket between samples?

Karen: You set up a de-con station. You use high pressure wash, steam, you can use Alconox, and then have to put it in your containment system with all that water and between samples, I would recommend actually using new brushes and dispose of your de-con water each time into your… So you can set up a decon, and I use a high-pressure wash and probably some scrubbing with an approved brush type with bristles that wouldn’t contribute to the PFAS.

Jack: And Dane, I’m gonna add to that, too. Maybe someone’s asked it already, but they often do, what de-con solutions can you use, and Karen mentioned Alconox, but we’ve use Liquinox, Citranox and a material called DeconIt. So those are some of the other examples of what you can use as de-con solutions.

Okay, great. Yeah, thank you very much, Jack. Actually, we did have some people asking that exact question. So, Jack, here’s another question for you. It’s in regards to the pollution response. Is there a quick reference way of identifying versions of AFFF foam that contains PFOS or PFOA? And those versions that does not contain such C2 AFFF?

Jack: Yeah, this is a great question. And it’s one that we see an awful lot. So, you know, in addition to going to the MSDS, if it’s an old material or an SDS, if it’s new material, the date in which it was manufactured will tell you a lot about how it was manufactured, and what potentially it might contain. I think the ITRC has done a great job in some of their guidance documents, of sort of outlining that history and helping people understand what they might look for in these different firefighting foam.

So it’s way more complex than just looking at the SDS. You got to do some of the background history research on that and have some conversations in terms of what people remember, conversations with suppliers. All that comes into play and then it helps you age date the material beyond some of the scientific and statistical techniques you can try in order to do that.

Dane: Okay, thank you, Jack. So this is a question for Kristen. And it is, “Given the colloidal nature of the carbon, I assume you need to understand its migration potential?”

Kristen: Absolutely. So yeah, we have a unique reagent, basically, with PlumeStop, and that it can distribute in the subsurface, but obviously we don’t want it to distribute forever. And so we have done a lot of research to understand how it sticks to various soil types. As a just general rule of thumb, if you have a really clean sand, it’ll have a thinner layer but also spread out wider, but it will continue to deposit onto that sand. If there’s more silt and clay around, it will deposit a little bit of a thicker layer, you can think of it, and it won’t necessarily go quite as far.

As a lens part of the assessment we do up front through really trying to understand what the geology looks like in the zone we’re injecting into. So we have an understanding of that. We can use that to help us design the total volumes, the concentrations, all that, what we need to do to make sure we get that distribution.

We also in some cases, do you have questions about will it go too far? Will it continue to move? Again, if there’s mostly clean sand and there’s not a whole lot of fines, there for it to stick to. In those cases, we do have some processes and some procedures we can do to make sure that it doesn’t go too far. We call it a parking agent; we can utilize that to make sure that it stops once it gets to that area that we need it to get to.

And that is one thing we have done on a few cases when it’s really necessary. So yeah, having to understand how it’s going to travel is really important. And that’s something we look at up front to make sure we can design that appropriately spacing, and the formulations that we’re using.

Dane: All right. Thank you very much, Kristen. That’s going to be the end of our chat questions. If we didn’t get to your question someone will make an effort to follow up with you. For more information about services from anteagroup, please visit anteagroup.com. And if you’d like to learn more about remediation solutions from Regenesis, please visit Regenesis.com.

Thanks again very much to Jack Sheldon and Karen Cole and Dr. Kristen Thoreson and thanks to everyone who joined us. Have a great day.