 Well, welcome everybody to another of HydroTerror's webinars. Today we're joined by John Hunt from Venture, who's a bit of an industry legend, and he's going to talk to us about PFAS remediation, the role of ESD, sustainable practices, practicability and proportionality. And many thanks to Venture for giving John the time to present today. Before we get into things, I would like to begin by acknowledging that we conduct our work across this great land, and for that privilege we would like to thank the traditional owners. HydroTerror respectfully acknowledges the Boon Wurrung people of the Kulin Nation, where we are located today, and we pay our respects to their elders past, present and emerging. There's a picture of John Hunt wearing a suit, looking very smart. A little bit about John. So, John has a PhD and is a Senior Technical Advisor in Venture's contaminated site remediation group. He worked for Venture and its predecessor, T-Services and associated companies from 2000 to 2021, taking a mentoring role at GHD after retiring from Venture. But he's now back at Venture, I'm happy to say, and some of the work he's presenting here today was done with GHD. So there's a little bit of input from GHD there as well, so thank you to them too. Before joining the environmental industry, he was a coal research geologist at CSIRO, and that's where he did his PhD. And oil and gas exploration geologist with Delhi Petroleum and SO Australia Limited. In the remediation field, he started with GTA in the 90s doing in situ and ex situ remediation of total recoverable hydrocarbons and other contaminants in soil and groundwater. He then worked for ADI, which is Australian Defence Industries, on remediation of several former Defence Munition Manufacturing sites before moving to T-Services, for the Rhodes Peninsula Dioxin Remediation Tender. During his career in site remediation, he became interested in sustainability and has been a member of the Sustainable Remediation Forum Australia and New Zealand since its formation in the mid-2000s. He is a past president of Australian Land and Groundwater Association. We love your questions, and I'm sure John would love to get lots of questions to play as well. To raise a question, use the Q&A button at the top of your screen, and I will read those questions out once John has finished his presentation. We have a lot of people here today. Third largest number of registrants behind Susie Reichman and Mark Stuckey, but a great audience. So well done, and that shifts Phil Mulvey to fourth position. Phil, you're here. Why does Hydrotera run these? Well, we like to share knowledge. We like to facilitate education, and we like to hear from industry leaders. So many thanks to you, John, for presenting today. Before we move on to John's presentation, there is an aligned, I guess, what do we call it, symposium, I guess, aligned to this topic that we're talking about today, that ALGA is running next week, and recommend that as many of you who can should attend that. So that one's PFAS management into the future 2024 symposium in UTS Sydney on the 14th of March. Got over 150 delegates attending there. So please get in touch with ALGA if you want to learn more about PFAS. All right, John, I'd like to pass over to you now, and thanks very much for presenting. Thanks for the introduction, Richard, and thanks very much for putting these seminars on. It's good to see companies giving back to the industry, so to speak. And I'd like to thank Ventia for supporting me to be here, and GHD, where I learned all about PFAS. Next slide. Just for the record, I tried to avoid PFAS in my career. I figured someone else needed to keep doing the other stuff, but when I joined GHD, I was thrown into the PFAS washing machine, and I came out knowing a bit more about PFAS, but not too much more about remediation. It seems to me that remediation of PFAS uses the same methods and strategies that we've used in most other contaminants, and we're still waiting for the silver bullet to turn up. So my agenda today is basically a third, a third, a third. I'm going to speak on ecologically sustainable development, or ESD, using some notes that David Tully put together for surf ANZ. I'm then going to speak on sustainable remediation using some notes that Tony Scott put together for surf ANZ. And then I'm going to speak on a hypothetical PFAS remediation case study that I put together for GHD for the workshop next week. And the keywords through all of this will be practicability and proportionality. There's a lot of nomenclature in ESD, sustainable remediation, and the regulations that we deal with state to state. And it's good to know where it comes from and have a stab at what it might mean. Next one. So sustainable development all started with the Bruntland report in Belgium. You can see the definition there. The date's 1987. I was in the museum in Antwerp a few years ago, in South Florida, actually devoted to the Bruntland report and sustainability. So there you go. Haven't seen that in Australia yet. Next one. So following the Bruntland report, Australia put together a national strategy for ESD, which was endorsed by the Council of Australian Governments in December 1992. And it was then up to the states to implement ESD and their regulation and legislation. And as you can, as you all see as we go through the language in ESD actually keeps appearing in our regulations as they're updated, possibly with a different focus from time to time, but basically that's where it's coming from. So it's good to understand. Next one. All of the state based contaminated land legislation in fact includes objects to promote the principles of ESD. For instance, in the ASC NEPM 2013. Next one. And I wouldn't be surprised now that there's a sustainable remediation standard out an Australian standard that auditors and EPAs start to ask for formal sustainability analysis when you're doing your raps going forward. I know that's already happening in some states and with some auditors. And I expect it would become more prevalent in the future. So some of the keywords and concepts. Sustainable development meets the needs to the present without compromising the needs of the future. ESD has six principles and I've listed them all there. And you will recognize some of them. Sustainable use has the words has words like prudent, rational, wise and appropriate. How you measure those things of course is a bit of a difficult task. Integration talks about integrating environmental, economic and social considerations and that's straight into the standard for sustainable remediation. The precautionary principle. And I actually stated the precautionary principle there in the orange highlighting and there's lots of different ways of saying it. But in the precautionary principle, it says that a zero risk standard is inappropriate and it talks about proportionality. That is the effort to address risk should be proportional to the nature of the risk. And you'll find that language keeps coming back into regulations and most recently I think into the Victorian regulation. The remaining three principles you'll be aware of as well, but they're not really what I'm focusing on. If anyone wants to get a practical field for how ESD is applied in the law, Justice Brian J Preston, Chief Judge of the Land Environment Court in New South Wales has made a career of selecting cases to illustrate the application of the principles of ESD. And it makes for very interesting reading that title there, which Stephanie Martin at GHD found was actually a talk he gave recently at a seminar on PFAS in Queensland. I think it was to do with PFAS replacement. Next one. So keywords in the guidelines, precautionary principle, cost effective, risk based decisions, sustainability. And in the intergovernment agreement on PFAS contamination talks about financially and logistically sustainable. So financially is a fair consideration. Proportionate to risk, so there's our proportionality and managing risks in a way that's financially and logistically feasible. Next one. In regulations, and I think this is from the Victorian regulation, we find this CUSFARP or ESFARP if you're working on defence sites clean up so far as reasonably practicable. I looked up reasonable and practicable in the dictionary. And that's what I found in the first two cases. Once again, things that are more certainly reasonable, difficult to measure. But in the regulation, they talk about proportionate controls. So eliminate engineering administrative, which speaks directly to remediation options and the greater the risk, the greater the controls, which is another expression of proportionality. Next one. Before we do so, SUSFARP on defence sites, what's SUSFARP stand for? It's just the CU is missing. ESFARP, so far as reasonably practicable. Thanks. So this is the section on sustainable remediation. It's a sustainable remediation forum of Australia and New Zealand and this material here is taken from the website. If you want to look at more detail, you can go to the website and find these talks. Its mission statement is the development and promotion of sustainable practices and thinking for application to contaminated land and groundwater projects. Next one. We also have a soil quality and sustainable remediation standard AS ISO 18504. So that should be 2022. The idea of sustainability in terms of the three considerations, social environmental and economic is shown in the Venn diagram on the right, which is a handy way of thinking about it. Next one. As of the background, the ISO came out in 2017 and Paul Nathaniel, who many of you will have come across at conferences here, was I think the chair of that committee and whipped it through the process. It was adopted as a British standard in 2017. It went on the Australian standard to do list, but they forgot about it. So it didn't happen until 2022. It was adopted before. It's probably fair game now for EPAs and auditors to ask for your SR analysis in a wrap, given that we have a standard. And what I'm doing today is basically just demonstrating a very simple application of the standard to PFAS remediation. There's what's covered in the standard. It's only 23 pages. It's simple, readable, usable and flexible. It's not a normative standard. So it doesn't tell you what to do. It tells you how to do it. Next one. The basic definition of sustainable remediation is elimination and control of unacceptable risks in a safe and timely manner while optimizing environmental, social and economic value of the work. It's about risk and risk management. It's not actually about this method or that method or this chemistry or that device. So it refers to demonstrably breaking the source pathway receptor linkages, and that can be done using very simple methods like capping and cap and contain all the way to very complex methods like thermal treatment, which is always site and place and time specific. And the thought at the bottom is mine. Sustainable remediation is time and place specific. And to figure that out, think about what you can do on a countryside versus what you can do on a city site when it comes to remediation simply because of land value. It's about the outcome of comparing feasible options right now. And it's not about taking a solution and greening it so to speak, substituting solar energy for diesel generation or something like that. It's about holistically thinking about problems. Next one. Basically, it allows for the process to be done simply where that's the appropriate thing to do or if you have complicated projects and the solutions are very similar, then you may need to go to a much more complicated analysis of sustainability. But as the general rule, you do the simplest form that you can that's appropriate for the problem being thought about. Next one. The process outline in the standard you'll all be familiar with framing the project, identifying the options, assessing the options, selecting the preferred strategy and then developing the plan. Next one. And the key to the key principles when you're making decisions in a sustainability context for remediation are to identify legal requirements. So you if a sustainable solution is outside what's legally allowed, then it's not sustainable by definition under the standard. So you can't have any unacceptable risks as defined by law to human health in the environment and no unacceptable risks to workers or nearby communities. And decision making should be transparent, of course, and the good governments would always mean that there's significant or appropriate stakeholder involvement. Now the nomenclature, which I need to talk about is dimensions indicators and metrics the dimensions you're familiar with economic social environment indicators are characteristics that represent a sustainability effect. They can be compared across options. So something like 10 kilometers if you've got movements on road for CO2E if you've got emissions. Metrics are the way you measure the indicator can be dollars a meter cube for a financial dimension, for instance, 10 kilometers for for social impacts via truck movements on road. Risk reduction noise in decibels and so on and so forth. Next one. Some things, of course, are difficult or hard to measure or can't be measured because they're very subjective and some social and environmental values fall into that category. So you end up doing sustainability analysis with some things that can be measured and some that are difficult to measure. The guideline has lots of metrics. These are the ones I'm looking at today for my little hypothetical. I'm looking at direct cost. If we knew the direct cost for all the remediation options that we consider, we'd be streets ahead. But usually we don't because it's a bit opaque. Actually, you know, you've got to have the tools and the experience to work out the direct costs. I'm also looking at CO2E emissions. So in remediation, we dig stuff up. We transport it around. We run it through treatment plants. We move it again. We put it back in the ground. We bring in backfill. They all have emissions associated with them. And that's a good way, a good thing that's fairly, I find fairly easy to calculate and compare. My social indicator was disturbance by trucks on roads, not trucks off roads. And I measured that in tonne kilometers. So I just figured out how many tons went, how many kilometers for my various options. And the final one was risk reduction, which I measured by looking at how much of the contaminant was destroyed or immobilized. They are having different risk footprints, of course. Next one. At the end of the day, the sustainable remediation standard is more or less a checklist. And I think that most of us in fact have been using elements of the checklist when we do our assessments. But the standard basically gives you a systematic way of going about it. And believe it or not, when you do it systematically, you will discover new things and get new insights that you might not have had previously. So I guess in retrospect, most remediation options assessments do arrive at more or less sustainable outcomes. But if you want to get the Sustainable Remediation Award from ALGA, then you need to go through this checklist up front about how sustainable it was, actually put this out of the auditor asks, it'll be there. Next one. You broke up a little bit during that slide, John. Oh, okay. Yeah, do this up front. If you want the Sustainable Remediation Award from ALGA, you can't do it after the fact. And if you do it up front and the auditor or the EPA asks for it, there it will be. Thanks. So our hypothetical site is an airfield that's been using a lot of AFFF historically for fire training. It's an alluvial soil. I've got some quantities of soil and some concentrations of PFAS. You can work out the soil mass and the PFAS mass. The bug graphs on the right show soil mass in red and PFAS masses in red. It's in grams. And soil masses in blue and it's in tons. And the funny scaling is because I've got them both on the same diagram of course. But you can see the typical pattern that I've seen throughout my career for most contaminants is there's a small amount of matrix with a large amount of contamination and then a relatively large amount of matrix with a small amount of contamination. And what I've done is I have worked up a remediation strategy where I'm treating all of that PFAS right down to the lower levels. And then I'm going to have a look at proportionality at the end. The cross section shows a typical sort of PFAS distribution on a site. It's only in the PFAS is in the top two meters. The hotspot is fairly shallow. It's in fact from half a meter to one meter and surprise surprise it's deleted. It's depleted in the upper half meter because we've got a lot of mass flux into surface water. So the objective of a hypothetical is to basically reduce the mass flux to surface water as much as we can. And I'm going to do that in this case by excavating and either treating and reusing or treating and destroying. I'm assuming that the risk is proportional to the mass and that's a very simple assumption. Obviously given the way the contaminations layered you could get into all sorts of debates and come up with much cleverer models. But that's my simple assumption. Next one. So in terms of the process we determine human health and environmental risks. And in this case we've decided there due to the the mass of contaminant present compare with acceptable levels. Determine the required concentration mass or mass flux reduction remediate and then monitor in this hypothetical. Some of the hotspots are quite hot and do represent a risk to human health but only in small areas. But the main driver is environmental risk of course because of the mass flux in the surface water. We have offsite aquatic ecosystems freshwater ecosystems that have to be protected. There's the there's our breakdown of PFAS mass and soil mass again. And you can see that the greater than 50 milligrams a kilogram which is in a very small amount of soil contains 30% of the mass. And you can read down the table there and immediately remediation options will start popping into your mind. Next one. Just before you do say this mass flux reduction to do a baseline flux estimation first and then. All of all of these sites would have fairly I'm going to say long winded assessments occurring and monitoring of surface water mass flux. The hypothetical the main risk pathway is mass flux into surface water. And given it at the end we're not going to remediate everything monitoring post remediation is very important to demonstrate just how much the mass flux was reduced by. Professor Professor Ilke Wallace I think it flinders uni has a very nicely calibrated model that can actually look at mass flux from hotspots or from PFAS in soil. And probably model before and after mass fluxes. But at the end of the day monitoring needs to be done. You probably hadn't thought about that Richard. Next one. So just for the record of course we're going to try and remove as much PFAS as we can but at the end of the day there are practical considerations if you are going to excavate you probably can't excavate closer than X. Another 10% of mass is in the very low level class which for the hypothetical I'm mediating but at the end of the day you probably went with that when you apply proportionality to the exercise. And of course. So you might be removing my dependent on that but it could actually dig in less than less than that even without being dead as. And so you need to honor this one. John I think you better go. Have I lost you frozen. You did. You did get very unclear there. Have you tried that slide. Okay. Considering we want to remove mass there are some practical limitations at the end of the day on most sites you will be leading PFAS around services that you can't approach with excavators. And that could be around 10%. And if you leave the low level halo that could be another 10% of the mass. So despite your best endeavors to remove as much as you can there will be practical limitations even on sites where you excavate. Next one. What's in the halo is of interest to me my hypothetical I think has 10% of the mass in the halo. These cumulative graphs of PFAS and soil from a 3d model suggest that it could be a lot more mass in the halo. Personally, I'm not sure that I believe them because 3d models tend to overestimate what's in the halo around hotspots particularly as you move into higher confidence intervals if you're doing. So I answered the analysis on the results and these graphs here for a 70% confidence interval of a 3d model. I simply raise it because it is difficult to actually estimate how much mass is in the halo. Next one. The options I looked at. The first three options managed cap and contain and encapsulation aren't being done in my hypothetical because we can excavate and because the site owner doesn't want to have to manage the PFAS on site. The options that I've constant immobilize and reuse immobilize and dispose to landfill so in the hypothetical this state will let you take PFAS to landfill but it has to be immobilized to meet leachability criteria. And the third one is thermal treatment and reuse and the only facilities that do that at the moment are in Victoria. I'm traveling a thousand kilometers by road for thermal treatment. I'm traveling a hundred kilometers by truck for disposal. And there you can see my plant on site doing some immobilization. I think that's actually EPS's plant just to give EPS a plug. Next one. When I did my metrics, I costed up those five options. One was to immobilize and reuse everything except for material over 50 kilograms and 50 milligrams a kilogram that always went to thermal treatment because under the nemp you can't actually reuse that on site. The second option was immobilize and dispose all now we all know that silly because it's going to cost an arm and a leg but I put it in just so we could see that. The third one was to thermally treat all and we all know that silly too because we're not going to take the whole lot down to Victoria and that's going to cost more than an arm and a leg but I put it in just so you could see that. And the four and five immobilize and reuse combinations immobilize and dispose and thermal treatment and five is immobilize and reuse and thermal treatment without immobilize and dispose. So those are the five options I costed up in my hypothetical you can see the results below total cost thermal treatment which is in the middle is obviously not practicable not financially practicable. And immobilization and disposal is also quite expensive if you do it for everything. The options one four and five however have similar costs so in the sustainability analysis those are the ones you'll be focusing on and trying to discriminate between them. The two charts to the right just so rates per cubic meter or per tonne and they basically follow the same pattern and finally rate per kilogram of PFAS treated which also follows the same pattern. Remembering that we didn't treat all the PFAS because we left some around the services and maybe we left the halo. The second thing that's easy to consider are the metrics around risk which can be an environmental or a social metric. And you can check those out in the bar graph to the right thermal treatment obviously destroys all every one of them has the 50 greater than 50 milligrams per kilogram destroyed by thermal which is the green bit at the top. And then the rest of the risk could see the going to landfill which removes the risk from the site but transfers it to the landfill perhaps. Or reusing on site which then brings in management and administration because these things tend to get lost with time where they are and what we should or shouldn't do and that's a very important risk management consideration. The older I get the more important it becomes next one. For social metrics I did off road tonne kilometers on road tonne kilometers and rail tonne kilometers. I'm not going to tell you the answer you've got to go to the symposium next week if you want to see that but you can probably guess what it is. The off the offsite road has the highest impact of course because it's affecting communities. Next one. Another environmental metrics CO2E I'm not telling you the answer either you've got to go to the symposium to see that in general. However, earthworks don't contribute a lot to CO2E transport doesn't consider a lot to contribute a lot to CO2E immobilization. Well if you want to find out how much that contributes you better do some surfing no pun intended on the web. And of course we all know that thermal treatment has very high CO2Es and therefore must not be sustainable. I'm joking of course because thermal treatment can be and is sustainable in the right circumstances like treating that greater than 50 that by law you can't do anything with except for treat and destroy. Next one. So in considering our practicability. The regulation would say the greater the risk the greater the controls and what would what I'm what I'm going to do in my solution is I'm going to destroy the highest risk material so the greater than 50 milligrams a kilogram and this site actually had up to I think 200 milligrams a kilogram on it. The site my hypotheticals based on so there are some pretty high levels out there when I started I was told one milligram per kilogram was a high number for PFAS. The 20 to 50 milligrams per kilogram you can destroy it you can landfill it or you could reuse it on site I haven't found anyone who wants to immobilize and reuse simply because of the risk of managing it. The one to 20 could be immobilized and reused and often is and the zero point one to one can also be immobilized and reused or just simply managed without any treatment. So practicability and proportionality how do they apply let's have a look at the next slide. In terms of the options I considered immobilize and reuse all the risk the management risk is too high the ongoing management and that's not reasonably practicable. Immobilize and dispose all that's not practical simply because of the cost and the social impacts and thermal treatment of all isn't practicable simply because of the cost. What is reasonably practicable is immobilization and reuse immobilization and disposal and thermal treatment in some sort of combination. Now thinking about proportionate of course, we have 10% of the PFAS mass in the halo, but it accounts for 40% of the cost if you treat everything in the hypothetical. And that's where I'd be doing that sort of analysis of mass distributions to figure out what is proportionate it's really a value for money thing how much risk. What's the cost benefit for reducing risk and in this hypothetical we can reduce 90% of the risk by spending 60% of the money and to get the extra 10% of the risk we'd have to spend another 40%. So that's how I would see proportionality of applying next one. Does the reduction actually really equate to the risk though so. Well that's a good question and we could spend many many minutes or many hours days even talking about that. I made the very clever simplifying assumption that it did early in my hypothetical so for my hypothetical it does. You're asking is it a case in reality and I mentioned looking at the cross section, particularly given that there's depletion in the upper half meter. There still is flux coming from the lower from the next half meter down in back into the upper half meter of course. And you could develop a much more complicated rationale in your remediation options assessment and then do you sustain ability analysis on that. My hypothetical fortunately is very simple so so I can in less hypothetical sort of situations do you still approach still apply that sort of logic or do you have to go to a more complex. Well you can go to a more complex remediation proposal and then assess it and you're doing the sustainability analysis will be more complicated you might have to do models and calculations you know of flux rates and things like that. I'm just trying to keep it simple to demonstrate how it can be done in a simple case and then it's up to everyone to go off and apply it to their more complicated cases would would be my answer. No worries. And doing a very simple analysis will put you right into the right ballpark. You know you can you can get rid of the the things that obviously aren't going to fly or maybe they obviously weren't going to fly or it wasn't obvious they wouldn't fly, but you can use it to eliminate options and then you've got to do a much more detailed analysis of the two or three that remain. Makes sense. So in conclusion, thinking about PFAS and risk and risk management you insights where you can actually do something as opposed to sites where you can't and some sites you can't you've got a cap or cap and contain that sort of thing but if you can do something. You start from the top down because the risk in this model and I think in reality is associated with the mass. And eventually at some stage you will run out of money or technology or something but you start at the top. In terms of proportionate of course you look at the mass the risk and the cost and for this model here we had an inflection around one milligram a kilogram so we we actually ended up treating everything above one milligram a kilogram and leaving the halo in place to be managed. Once again that's very site specific because I was looking at the site the other day that where the concentrations range from about 10 down to 0.1. And it came it actually remediated down to about 0.1 maybe they I think they went below 0.1. So that that'll always be site specific. In terms of the important learnings from all of this I always go back to understand the problem if you don't understand the problem you're not going to develop the right solution. So spend more time understanding the problem actually looking at the side assessments in detail doing the 3d models doing the mass flux measurements and. If you understand the problem properly then you're going to develop an appropriate solution if you don't your engineers will go off and do a very good job of putting the wrong solution in place. Number two develop sustainable remediation metrics for your solutions. And number three find ways of identifying that concept in ESD of proportionate action action that's proportionate to the risks. So between all those three you'll you should come up with the best answer possible for the site today. It may not be the best answer 10 years down the track. Maybe the regulations will change because at the moment applying the precautionary principle in regulation where we're being very precautionary because we don't really know what the effects are of PFAS on the environment or human health for that matter. And that's where I'll leave it time for questions. Thanks very much John. All right. Early bird questions. Thanks for everyone I sent these in. Number one how can Australia's airports work on soil remediation has the horse already bolted. This is a pretty tricky question. In fact I proposed a presentation with with that has the horse already bolted in the title. People got very nervous about talking about it. Obviously harking back to our cross section PFAS has been around for decades and most of these sites show depletion in the top half meter. So to some extent the horse has bolted but there is still a heck of a lot of mass left in the ground because the rate of mass flux to actually get all of that PFAS out into the environment is going to take many more decades to centuries. So I think yes if you can remediate it you should because basically it's not out there yet but it will be one day if you don't do something about it. Number two is there an online real-time analysis method for PFAS in soil or do we rely on lab testing? To my knowledge no online real-time we're relying on lab testing. It would be nice if there was something even that would give you relative readings in the field. Well you know 10 years ago I saw a presentation at Battelle by a school kid who developed a method for shaking water in a vial and measuring the thickness of the froth on top that actually gave a reasonable rough correlation of PFAS content for the site they were looking at. But I'm not aware of any sophisticated calibrated field methods but I'm not really the right person to answer that question either. I'm not aware of any either but we can do a bit of research into that one. Number three would you recommend using bioremediation as a sustainable remediation method if so which bioremediation method do you recommend? Well I like this question because you could substitute any method for bioremediation. You could say immobilization, you could say thermal. I think the whole point of the talk is there is no such thing as an innately sustainable method. You've always got to look at the site and the context. If you have an inner city site with development pressure bioremediation is not the sustainable method to use even if it's just got simple TRHs on it. Not the sustainable method on site. You might do it off site. Which method you would use once again depends on the situation. If you're out in the countryside somewhere you might like to land farm happily away because the site's got no value and no pressure. If you're somewhere else if you're trying to deal with PAHs you're going to need to do something a bit more active. Is bioremediation a pretty slow process with the PAHs? Well you need time and space and in some circumstances you don't have time and space. By definition it won't be sustainable at that site simply because of the context. It may be sustainable at other sites that don't have the same constraints on them or it may be sustainable to do it off site. You simply go through the metrics and look at the options or look at the options and go through the metrics. And bioremediation is like most most technologies it has a sweet spot where it's very time and cost effective. But as you run into more difficult contaminants of concern or more difficult matrices the costs and the time will go up. And eventually you'll stretch it to the point where it's no longer feasible. You know technically it can't be done or financially it can't be done or suddenly it costs the same as doing something a lot more high tech like thermal treatment. So there's no sort of one answer to this it's always in the context of time and place. Would it be a challenge for regulators to work past the proprietary information on chemicals in commercial products? I'm not sure I understand the question and even if I did I'm not the person to answer that. Okay I think I'm the same but number five the agricultural impacts of not applying biosolids to land versus continued and improved monitoring of PFAS in biosolids. I think what we're talking about there is does PFAS in biosolids pose a risk? Do we have a cost effective way to monitor them? I can't really answer that one I'm not a biosolid specialist but I think Matthew Askelund at ADE has spoken at great lengths about this. I've done some very good presentations at some recent PFAS symposia. In fact the one last year that's the predecessor of the symposium on next week. So I would highly recommend going talk to him or Google the stuff up and see what he had to say. How does the concept of ESD and proportionality apply to the Queensland DESI EV approach and 440ZF of the EP Act? I don't know I didn't have time to look up 440ZF of the EP Act before the talk. But like I said ESD was a national concept and it was up to each state to implement it. And what I reckon happens is every time the regulations every five or ten years whatever the cycle is every time they get revamped upgraded ESD concepts come back into them maybe in a different focus. So they all are related to ESD and I think the regulators are all committed to ESD and that's why the language keeps appearing in the regulations. Alright number seven PFAS and vapour intrusion. As I said previously vapour intrusion isn't really a PFAS issue for the PFAS in soil but I am aware of a site where I think it had an industrial process using PFAS as a blanket on something hot where the PFAS was actually in the off gas stream coming out of the process. But that's really the exception rather than the rule and then in a much larger context I think PFAS is moving in the environment or in the atmosphere as an aerosol and circulating quite widely. And the famous case is PFAS turning up in the polar bears in the north polar course possibly by atmospheric mechanisms and redeposition and then getting into the food chain. Number eight hi John what is your opinion on the National Remediation Framework Documents as another tool in sustainable remedial design. Yeah the NRF has some documentation basic documentation on methods which if you're not familiar with methods that's a good place to start. I think when it was finished when the first version came out we were asked where to next and most of the methods there could be expanded on in quite some detail. So it is limited in that sense but there are resources on the internet if you don't know about methods. It does have a cost benefit and sustainability analysis tool that I find a bit clumsy to use I guess. It is it was developed at the request of some of the multinationals because there was no cost benefit guidance in Australia for big resources projects. And so while it can be applied to small remediation projects what's in the ISO or the AS ISO is a lot simpler and more straightforward I find. But if you're into CBA go to the NRF. Number nine. John's views on how sustainability decisions are made with disposal and thermal. Well I have in fact of course touched on that today. If you look at the I think the analysis of risk for the different methods thermal destroys the PFAS down to 99.9999%. Having said that the treated soil to my knowledge is not actually being reused in the countryside in Victoria. But it is being reused beneficially on the landfills as cover and roadways and that sort of thing. If you send it to landfill that's a whole different issue you've simply transferred the risk somewhere else and in the Australian context it probably does sit with the landfills. But in the US context of course people who put stuff in landfills often find themselves on the wrong end of the lawsuit when the landfill closes or the owners disappear or whatever. It's a risk transference thing anyway and that depends on the value of the people who are making the remediation decisions and they're often clients with budgets and their own view on risks that they will and won't accept and they will or won't manage. So in the US if you're a landfill operator and you received say some PFAS contaminated soil and then say you were the remediation contractor and the original side owner went bust and then there was a case against the landfill. Would the risk sit with the contractor or how does that work? In the US to my knowledge the risk seems to go back to the owners of the material that went into the landfill and possibly that's where the landfills are shut and the operators no longer exist and that sort of thing. If you then have problems coming from historic dumping of chemicals in landfills and back in the bad old days they may not have been very well designed landfills of course. I think it's actually the owners of the material that went in that end up on the hook and there can be lots and lots of them of course. It's sort of interesting in the context of something like pesticides applied on paddocks and now we've changed our view on them. Something to ponder. 10 site examples of where stabilised PFAS soils have been accepted and reused on sites in accordance with the NEP or is it meant to be NEPM? Well it is happening but it's always to my knowledge it's only happened on sites so to speak. If you immobilise soil on your site you can reuse it on your site in accordance with the NEP. I'm not aware of anywhere where someone's immobilised soil and found a home for off the site for instance. I really can't be more specific than that without applying to people for permission to talk about their sites. No worries. Number 11, to what extent have the respective state regulators been engaged in development of the standard? Well I suppose it depends which standard you're talking about. If you're talking about ESD then the states were I imagine intimately involved in the process. I certainly wasn't. I was around at the time which would have been the early 90s. If you're talking about sustainable remediation the standard I'm not sure. Being sort of led by an international committee I'm not sure whether regulators around the world were actually involved at any stage. And if you're talking about the standards that apply to PFAS then yes the state regulators will have been involved in the NEPM and the NEP of course. So the difference between the NEP and the NEPM just for me? The NEPM we're all familiar with sort of the overarching documents on land contamination. The NEP I've been around for a while and when I started off there were NMPs not NEMPs. And there were NMPs for dioxins and furans, PCBs, OCPs and HCB applying only to the Oracle Botany site. So I see the PFAS NEP as sort of the fifth or sixth NMP national management plan but somebody thought it was appropriate to put the word environment into the title this time. So it's a plan that applies specifically to PFAS whereas the NEPM it sort of applies across the board and deals with you know lists of chemicals. Thanks for that. Well we've got a lot of questions coming through in the Q&A, we've got a charge onto that. Malcolm Barker, thanks for the presentation. What can be done when the PFAS is already well off the site of initiation in the groundwater? Well you'd need to look at the context. You need to do your risk assessment on the groundwater pathway and where it's going to and what receptors it's affecting to determine what the real risk is and whether you should or shouldn't take action. Obviously if it's a situation where you've got high concentrations and you've got sensitive down gradient receptors you can apply the usual groundwater remediation strategies from containment down to pump and treat and that sort of thing. And hopefully there'll be some more innovative solutions coming there with injection of nanoparticles and things to lock plumes up etc etc. I would point out that for most sites I've seen and I think most sites that everyone's seen groundwater is not the main pathway for PFAS and not the main risk for PFAS it's actually the surface water pathway. Okay there's a question from Ken Gilbert about are the mass buckets based on thresholds? Well the concentration classes I was dealing with were I guess classes of convenience not necessarily of risk. The top one, the greater than 50 is related to the NEMP and that greater than 50 appears in the other national management plans for OCBs and PCBs and HCB. Below that though are simply classes of convenience for the hypothetical and the hypothetical is sort of based on multiple sites and that sort of formula works where you've got high concentrations i.e. greater than 50 down to low concentrations. If your site went from 10 milligrams a kilogram down to .01 whatever then you might subdivide it into other classes. If you're using 3D models to actually develop sort of an understanding of how the mass is distributed you can interrogate those models by whatever class increments you want to discover how the mass is distributed. But with 3D models there's a lot to be known about how to apply them of course and if your data going in isn't good then the answer coming out won't be good either. You mentioned that they tend to overestimate the mass. Yeah this was working with the EVS model which does apply certain confidence intervals you can actually calculate confidence intervals. Some models don't do that they just sort of deal with the most likely case or the 50% confidence interval. You know the 50% the value may be higher or maybe lower with equal confidence. What we found with the EVS model was you needed to use higher confidence intervals to better define the hot spots. But if you applied the same higher confidence interval to the low concentrations then you tended to overestimate what was in them. And when you look at those cumulative plots I had there from 0.1 to 1 there are 9 decimal points but there was 40% of the mass. So that's 3 to 4% per decimal point. But from 1 to 150 there's 150 milligrams a kilogram and there's 40% of the mass so that's only half a percent per milligram per kilogram. And the sensitivity of 9 decimal points having 40% of the mass it tells you if you make a small error in selecting the concentration in that low concentration zone you're going to have a big impact on the amount of mass you calculate. If you make the same error for the rest you won't it's just a mathematical artifact. So I get very suspicious. You've got to be very questioning when you see model outcomes I guess make sure they make sense. So presumably you give a range when you're doing these sorts of things based on those different estimates of community confidence. Yeah it will be site specific. It depends on what range of concentrations you're dealing with in the first place. Okay. All right next question from Ron Blankenforth. I think the question is, can you use hemp to remediate PFAS in soils? Oh I don't know. Ron likes hemp. And where does the PFAS in soil come from? Where does it come from? It's totally made to start off with somebody put it there. Usually it comes from firefighting training on airport sites. And lots of other industrial sites. You'd be surprised the number of people I've spoken to in my mentoring role. Younger scientists who tell me, oh yeah we used to go to Christmas parties at the such and such a site and they'd foam it up for us to play in the foam. I'm just surprised by the number of people who can tell me that. It didn't happen to me when I was a kid. Next question from Malcolm Barker. Leaving the low level PFAS means you are leaving a risk. When is that acceptable as far as concentration? Well once again that would be site specific and you'd have to do a risk assessment. But at the end of the day it's also a practicability issue because if we don't have the financial resources to address that low level concentration the risk will remain and we may have to find other ways to deal with it. There are people looking at, given that the risk will be it gets mobilized into surface water. The question is can we actually trap it in the surface water. There are people looking at all sorts of innovative ways to put funneling gates in the streams or carbon beds in the streams or carbon coated pebbles in the streams that will take the PFAS out. The problem is the flow regimes are very peaky in surface waters. Of course you get very large flows in very short periods of time and designing treatment processes to actually try and capture the flux is extremely difficult. Better to try and address the source but it's not going to be done everywhere. We just don't have the resources nationally to do it. Yeah so it seems that's more about take as much out as she can afford to do but there'll be this residual in most instances. Yeah exactly and that's where this proportionality thing comes in if you can remove 90% of the mass well that's a great thing to do. Number one let's get rid of 90% of the mass and then stress about the 10% that's left but you know let's get the 90% out to start off with. I'm reminded in fact I've been around for long enough I use the Dutch guidelines back in the 90s and the Dutch guidelines to sort of clean up everything everywhere to nothing. Now in the northeast the Dutch suddenly realized they were spending lots of money and they went and surveyed the hot they took a pause and they took five years and surveyed all of the rest of the problems in in the Netherlands environmental problems and they figured out they would bankrupt themselves you know a thousand times over in the next hundred years if they kept going with the Dutch guidelines so they in fact adopted a totally different remediation strategy and created sort of regions of contamination instead of having everyone fighting with lawyers about who did what they forced them all into groupings to address contamination in regions and they did innovative things like pumping groundwater for heating and doing remediation of the water on the way through and totally changed their strategy but the bottom line was they didn't have the resources to do what their regulations said they should be doing so that's a very financial issue is very important and like I say we start at the top and stop when you run out of money. Just as a general comment we used to do a lot of sort of environmental management plans which had a long-term monitoring component to them I'm not sure if they were ever really implemented properly like it's always been the weak point you know once something's been built I suppose that's just another pondering next one from Laura Tan Do you also monitor and manage cumulative concentrations of PFAS at receptors that have been transported via surface water? It's kind of outside my area of expertise but I know the risk assessors will actually be doing biota sampling and that sort of thing particularly for surface water systems where you've got birds and fish and mammals involved so yes it does happen and it has a place I'm sure it's a very important field of endeavor in its own right Well it's part of risk assessment It was a pretty good presentation at one of the Algar ECO forums up in Newcastle where they had a study of the PFAS built up in turtles that they were looking at that was pretty dramatic in terms of the impacts I think on the hardness of the eggs Alright next question, James Stewart James from Always Carbon Super presentation and very interesting information Can biochar be used to capture and immobilize PFAS? Is it being done in Australia yet? Well we know that PFAS binds to carbon so yes I'm sure you can use biochar but that's not the question I'd be asking what's the efficiency of the capture and this is something I'm not going to tell you the answer to in any detail we've got to go to the symposium next week to find this out and there's some really interesting stuff around on this do some googling, try biochar pack US Forestry Service and that's as much clue as I'm going to give you Andy Hitts, next one Understand this is from Laura Tan understanding of PFAS impact on flora in the pulbara is limited and therefore it is difficult to risk assess are you aware of any research being done in this space? Well there is certainly research being done on PFAS and vegetation the pulbara I don't know about and risk assessment isn't my forte but I would suggest that what's happening and the latest developments will be discussed at the symposium next week by risk assessors Malcolm Barker, how do you have ongoing evaluation of the PFAS as you excavate and dispose of material for every load? Well there's a couple of schools of thought on this and it depends a bit on time and space on budget you can dig up number one, you will have a good idea what's where once you've done your site assessment and you can actually proceed by digging to stockpiles and testing stockpiles appropriately and classifying and then doing whatever you need to do depending on how they classify the second school of thought which is also occurring is basically to do in situ classification so collect your assessment data at the density that you would be collecting it if you were doing classification in stockpile which means you've got to get a lot more assessment data classified in situ and then dig it straight to a truck and take it to treatment or to landfill or to immobilization and reuse and putting that extra time and effort in up front will speed up your field programs if time is a critical element and the EPA is to my knowledge I'm not aware of any EPA that hasn't that has rejected that approach providing the assessment data is at the correct density for waste classification according to whatever the state guidelines are What bulking factor do you use for that John? When you go from in situ to stockpile Sorry what? What bulking factor would you apply so like does it change? I'm not I can't remember bulking factors off the top of my head but the projects I worked on where we did in situ we did back calculate you know how many cubic meters in the ground equaled how many cubic meters in the stockpile because I think the regulations I'm not sure whether the regulations talk about in stockpile or in in situ cubic meters when they specify rates in remediation we always work from in situ cubic meters that's the basic unit of measurement and everything else stems from that usually it's in situ meters and tons because in situ meters can be surveyed and tons can be weighed if you put it in the stockpile it becomes the measurements are less certain I think so 1.6 comes to mind as a bulking factor Should mass reduction this is from Ken Gilbert should mass reduction be based on leachable limits rather than soil concentrations it could be I actually did this hypothetical was a site with PFOS plus PFHS on it and I've done quite a lot of correlation between leachability and concentration for those sorts of chemicals which are typical of some of the firefighting sites and there's a very good correlation so it's simpler to work with the concentration data but you do need to have a database of ASLPs or TCLPs if you're in New South Wales for waste classification purposes okay we've got about 12 questions to go you happy to get going for another 15 minutes John? sure thanks for that okay excuse my mug excellent okay this is from Christy Hansen good question Richard about the risk once one could argue that the associated risk doesn't change much across all these options just playing devil's advocate maybe don't pull any of it out I'm interpreting that question to mean the risk between immobilised and thermally treated whether the risks are the same which is always the question you know how long will it last because if you can immobilise it do you need to go the extra yard and thermally treat it using high grade packs and I'm not going to define what high grade packs are but we were seeing 99.99% reduction in leachability which is a pretty significant reduction and it's kind of equivalent to getting 99.9999% destruction in a thermal plant what's left is pretty small the question is how long will it last there's a lot of research going on in this area at the moment with accelerated leachabilities and all sorts of things and there are two questions one is how long will the carbon last and the second is how long will the absorption last now the carbon is interesting there's been a bit of research in the last decade on agriculturally improved soils in South America that date back thousands of years so the Inca and Aztec where they used charcoal as an additive to soil and you can still identify those agricultural areas today from the charcoal content and I think the latest I heard was that the researchers have come to a similar conclusion in terms of the longevity of the activated carbon having said that packed vessels are known for taking up oxygen and having oxygen deficient atmospheres and also spontaneous combustion so the carbon must be reacting with atmospheric oxygen and degrading slowly over time but it looks like the carbon is lasting thousands of years and the second question is how long will the PFAS stay absorbed and CSIRO has been doing some longitudinal studies with some samples that were immobilized a decade ago or more and left in a warehouse and now they've been pulled out and they're being reanalyzed I think it's part of a defence project and I think they've published the second round of longitudinal study was published recently and some of the packs are performing over time and some of them aren't so there's a lot more to be discovered there but it's looking promising that immobilization will have a similar outcome obviously not the same as thermal treatment but I'll be retired finally and one of that one comes up of course well it's good to raise that that's a nice segue into the next one what made you want to come back from retirement well I never really retired I just semi-retired and I find it fun it's still very interesting and stimulating for myself and maybe I've got something to contribute as well so pick my brains while you can not a question but Scott Carroll's got a comment that ADE have a mobile PFAS analyser might follow you up on that school I believe this to be quite accurate backed up by additional lab testing for peace of mind that's a good development then Brent Davie, good day Brent I don't think PFAS are regarded as being susceptible to bioremediation or biological breakdown in any event that's also my understanding there is some biotransformation goes on but not bioremediation however there are people trying bioremediation to see if they can crack it Scott Carroll has a question is there a best way to schedule the programme of works for a project so that it maximises the potential for sustainable outcomes yes and it's not to send me the request two weeks before Christmas but seriously if you run out of time if you don't do the work up front and you come in a rush you're not going to get the best solution it's always better to have a very holistic approach to these things identify the problem properly and that way you'll develop the right solution all of that takes time and money up front so it'll just be in some circumstances on the site owners as to whether you do or don't get the advantage of having time to plan the best solution okay an anonymous attendee do you find that EPA and regulations to be mostly helpful or mostly in the way of remediation oh that's a tricky one because when I started there were virtually no regulations we just did what we feel like we followed regulations from other countries I think the current generation of PFAS regulations are really really good actually they do allow flexibility and they do allow innovation the only complaint I would have is the time it takes to get them in place and that's just a function of the process of getting everyone to agree of course and getting all the technical people to put all the technical stuff together for consideration in the first place the process is unwieldy but I think the results are very good I think we've already answered the next question from Ron Blankinforth so the Luke Minix hi John have you any examples of the social aspect in ESG has been considered in detail not necessarily for PFAS the social dimension is always site specific as well you don't need to overcook it if it doesn't need to be overcooked but I've worked on projects that have had a year or more of consultation before anything happened then they've had regular consultation through 5 to 10 years of work I'm thinking of the roads remediation, so doxons and thermal plants and that sort of thing Orica Botany of course the Orica projects have all had very long ongoing community consultation that's been very well done as well I've worked on projects where the community meetings maybe two or three people turned up and some of the sites Kendall Bay for instance Germany did such a good job on the consultation that by the time it came to the project people literally weren't interested anymore they'd found out everything they needed to know and it sort of became a non-issue and then other projects that are very small they might just be door knocks and they're not going to impact people so you don't need to do the whole ongoing consultation Next question Where do you think the future of PFAS management within the regulatory space is headed? I think as I said before it's fairly early days and I view the regulations as very precautionary they're set at very low levels because you really don't know the answers and you can't be setting high levels if you don't know that they're acceptable so I'm expecting as the science matures that the regulations will move and possibly the concentrations will come up I know that there are some areas where numbers will change but that's conservative simply because the research has been done and the answers have changed views but once again the process of getting those changes into the regulations is fairly unwieldy Next question What is your opinion on activated carbon for PFAS remediation considering PFAS is only absorbed in this case? We've touched on that several times already and it comes down to that discussion of how long will the carbon last and how long will the absorption last At the moment as I said the carbon looks like it is fairly long lasting adsorption is different if the fluid is moving through the carbon it's very fast if the composition of the fluids change or the pH changes you could see desorption so that's a complication it's always going to be an area where there's some uncertainty and some monitoring required and I would observe in other areas like landfills and landfill liners they all have design lives and at the end of their design lives which are usually in decades will fail and the remediation needs to be redone now what the design life is of carbon I'm just not sure I don't think anyone knows but it's subject to ongoing research That's a good question Final question from Emilu Cook Is there opportunity to include the value of ecosystem services within the sustainability assessment for example loss of these associated with disposal of soil to landfill Say that one again Opportunity to Is there opportunity to include the value of ecosystem services within the sustainability assessment for example loss of these associated with disposal of soil to landfill So in terms of the assessment framework you're using and looking at the various options is there an assessment of potential impact of ecosystem between those I'd say there is but the concept of ecosystem services etc needs to be socialised perhaps in the regulatory community and the remediation community I'd like to talk to Emilu about that one offline Sounds like we left the trickiest question to the last That brings us to an end John Thank you very much for your contribution today It was fantastic and many thanks to everyone who attended as well Thanks Richard for the opportunity and thank you all for listening Hope you learned something