Vapor Intrusion: Impact on Environmental Due Diligence

Video Transcript

Dane: Hello and welcome everyone. My name is Dane Menke, I am the Digital Marketing Manager here at Regenesis in Land Science. Before we get started I have just a few administrative items to cover. Since we’re trying to keep this under an hour, today’s presentation will be conducted with the audience audio settings on mute. This will minimize unwanted background noise from the large number of participants joining us today.

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We are recording this webinar and a link to the recording will be emailed to you once it is available. In order to continue to sponsor events that are of value and worthy of your time, we will be sending out a brief survey following the webinar to get your feedback. Today’s presentation will focus on vapor intrusion and its impact on the environmental due diligence industry. With that I’d like to introduce our presenters here today. We are pleased to have with us Dr. Kenneth Tramm, Principal with Modern Geosciences, a Texas based engineering firm. Dr. Tramm’s day to day work includes air quality monitoring, environmental due diligence, risk-based closures, and remediation design.

Prior to founding Modern Geosciences, he directed environmental due diligence for two international engineering firms. He is also the author of “Environmental Due Diligence,” a professional handbook which provides a comprehensive guide to the due diligence process. We also have with us today Mr. Thomas Szocinski, Director of Vapor Intrusion at Land Science. Mr. Szocinski is a nationally recognized vapor intrusion expert with over 15 years’ experience as an environmental scientist, focusing on vapor intrusion assessment and mitigation, remediation, site assessment and brownfield site management.

He has served on both state and federal regulatory vapor intrusion review boards, assisting with the development of vapor intrusion and mitigation guidance, regulations and exposure criteria. All right, that concludes our introduction. So, now I’ll hand things over to Ken to get us started.

Dr. Tramm: Well, good morning or afternoon depending on where you sit. Thank you very much for the opportunity and I appreciate your time. So with that I’ll jump right in. So, first I’ll give us a plug and introduce Modern, perhaps, to those people that we’ve not worked with or had a chance to meet on site sometimes. We’re based in Texas but we’ve done stuff really in the adjoining states primarily but I’ve had the benefit of working probably about 25, 26 states now. I think you’ve covered our day-to-day stuff from your due diligence which we do a lot of and that leads to a lot of remediation and then I can lead to the vapor intrusion concerns that I often run into and the screening investigation and mitigation approaches we take. And then air quality being a natural offshoot from some of the tools and instruments that we have.

I’m the squirrelly looking guy and, not the very bottom right but one up. That’s us doing some real-time vapor intrusion and kind of building verification under different pressures. So, with that…so, as an overview for what I’d like to cover today is to mainly touch on why we’re talking about vapor intrusion. Well, now that the conversation is really going nationally so it’s probably not as new a question for you, but how does due diligence fit in with vapor intrusion and back and forth. And then a little bit on the history for those that haven’t covered this extensively but there’s lots of in-depth ones, I’ll try not to bore everybody with it but hit, what I at least believe, are the high points, and then dive into the screening part which factors into your due diligence. And then from that screening part, many of our clients today in this industry jump right to the mitigation component and then we’ll have Tom help us out from there. But I do have a take home slide from some of this as well.

All right, so my number one answer to that when I get this question of why is vapor intrusion a concern? Well, it turns out I’m giving this presentation right now from inside a building and most of you are probably sitting in a building and listening to it. So, many of these studies point as much as 90% of our time is spent indoors but I’d say on average at least 80% of it for all of us, is gonna be indoors. So, number one we’re in, right, so we’re there, we’re physically there. Number two, the dynamics of VOC migration preferentially moved from those higher concentrations that are beneath the structure and into a structure. We’ll touch a little more on that in a moment.

And then another nuance to it is, while these risk-based corrective action models that we use within a regulatory closure structure in the state that we’re working in, or in some cases, on a federal project that we’re working on, will often leave impacted media in place. Several of those models have not emphasized vapor intrusion when they were put together. Some of them don’t have an evaluation of that pathway at all. I won’t belabor that but there are some times a closure may not mean what you think it means, may not address every possible reuse that you may be looking at for a piece of property.

And in the last piece, is that that we have those closures with impact, not only on our sites where we might have these buildings that we are in today but they also go away from these sites and they’re not well behaved, they like to go to other properties too and they can make concerns there. So all these elements together make a reason that vapor intrusion’s kind of a newer concern perhaps to look at, but by and large, it may mean that closure which you hold in your hand when you’re doing your due diligence may not mean what it meant at the time that it was given.

So one piece of that puzzle was what is a VOC? So what compounds are normally the ones that we are gonna look at? So if I’m doing due diligence and I’m looking at different industries, certainly we’ve all become very accustomed to saying my recognized environmental condition perhaps is for this gas station, this dry cleaner and we have certain compounds that we know are related to those. Turns out several of those compounds, just by the nature of them being VOCs, which generically falls into definition of right, having a Henry constant. Even having one at least means that you’re a volatile. But in this case having, you know, the higher the number the more volatility you would expect so something greater than 0.1 perhaps. And then having a boiling point which is suggestive that this would be not in solid phase, you know, at standard temperature and pressure.

So, on the right you actually see a depiction of different Henry constants for different compounds but, by and large, which ones are the most common ones? Well, if they’re chlorinated, they’re the ones that we would expect to encounter at a dry cleaner, right, where 80% plus of the dry cleaners, at least up until prior to the last four or five years, were perc based. There’s a lot of history and elements that go with that, but, so tetrachloroethylene or PCE, trichloroethylene or TCE and several other chlorinated compounds related to industrial solvent use, some from fumigants, some from actually the manufacturing process.

So there’s a chlorinated grouping and we kind of throw arms around them and we think about them a little differently than we think about the petroleum grouping from a vapor intrusion concern, but those are your common actors. With those common actors, there are other elements such as naphthalenes and trimethylbenzenes, so I guess just single methylene but trimethylbenzenes too, that we’ve put into the SVOC category, but it doesn’t exclude other things that are volatile you may have concern with. I unfortunately have to wrestle methane for some of my clients and make sure that we design buildings to keep the future occupants safe. I’ve had a site in New Jersey with a mercury concern. So those can factor in. It does mean, you know, may for intrusion, that my number one concern for some of those but in some cases, it is. So physical properties allow it to become a concern because it’s going to volatilize and head on up, so that’s one part of the story.

So another piece of how I would answer that question is, who is asking it? Right. So, now it’s more formally part of our due diligence process with the passage of E15, 2713, right, the last phase one environmental site assessment standard that actually has an element of migrating vapor built into it for the environmental professional to make a decision and render their opinion on what a recognized environmental condition is. So more specifically the people who are asking me that question usually in the form of due diligence would be a sophisticated developer, maybe they’ve had a problem before, maybe they understand they want their asset to be worth everything that they wanted to be when they expected the project to be over. And actually having vapor intrusion come up late in the game could hurt that.

Sophisticated municipalities, lenders and equity partners, council is very good at introducing the conversation because there’s a lot of liability elements that come with it and some are very much intimately familiar with the deal-making process and what can derail it. And this is one of the obvious things that can derail, you know, a deal at the end of a transaction whether you’re construction side or even just the property sales side. Environmental insurance brokers, of course, because a lot of the way people actually get comfortable purchasing contaminated land is to actually have some backstop to the amount of environmental liability they’re gonna have and insurance brokers are now looking at this as part of their understanding of the site.

And that doesn’t mean I’m leaving the last one on purpose but state regulators some looking only at petroleum, some looking at chlorinated and petroleum, some only looking at site by site cases or if it’s only being something that’s being closed in a high-end regulatory program like a voluntary cleanup program. By the way, all these people are gonna ask, they may ask early in the conversation, they may ask late but these are your target audience, from at least my experience. Now the, “Why they’re asking.” I’ve kind of mentioned some of that as I was going through who they were. But your long-term worker, resident health risk, if you’re gonna put something together and you’re gonna have to occupy it to sell your widgets.

There is liability concerns for being responsible for having that structure and those people working in it, that can introduce certain third party liabilities. As I mentioned before, impact to an asset. Is it gonna be worth what you think it is? Or, is somebody gonna look at it and say, “You know what, you didn’t have this and this in it, so that’s too much risk for us.” Then just early in the process, they can anticipate the actual cost to address vapor intrusion into their business decision of, “Does this look like a piece of property we would want to take and redevelop?”

And then the last one is one of the hardest ones to grab, which is to stay ahead of changing state closure requirements. If you’re in a state where maybe there’s not a mature program for determining if vapor intrusion will be taken off the table for a specific property, it makes it hard to aim at that target. So with that said, you know, regulators may add activities limitations or the EPA or other entities may go back and look at their closures. I have more on that in a second.

One part for kind of the public consensus of is it a concern or not, is when we start to see commercials. I have a notation of one, I’m not giving them a plug, he’s probably great but, you know, there are specific commercials that you can find now that are actually just like the asbestos ones were, a long time ago. “Have you or anyone you know ever been exposed to asbestos?” Now substitute that with TCE. And the ubiquitous nature of TCE in industrial operations unfortunately means that’s a large audience.

All right, so diving in on the third-party liability element, I have two or three examples of really specific cases where things like this have popped up. If there’s anybody, you know, from the Grand Rapids area, they may know a lot more about this and I, but I try to watch, I have enough feelers and individuals and consultants I’ve worked with. They know I’m highly interested in this area but this was one that was at least came to my attention last year. But, you know, here’s a scenario where a historic dry cleaner has impacted the neighboring properties. And so people have developed those properties, have occupants in them, in this case, an apartment complex connected to this one.

So, it ended up that it’s made it onto a list, that list made it into, “Hey, let’s go check out those neighboring properties and see if they’re okay or not.” And so here you have a collision of a lowering criteria for certain chlorinated compounds and you have individuals going out and sampling a media that probably wasn’t part of what would’ve been a traditional closure even five to 10 years before. So the end result is that you get samples taken where people are actually in an area that requires them to be removed from their building. In fact, that fence that you see up in the top right, that is from the site.

So the last thing my clients want is a letter after they’ve already built maybe an apartment complex or whatever was, you know, on their agenda. But the County Health Department sending a letter that, “Hey, you’re exceeding these things and either A, you have to take some samples or B you need to actually outright come on out and you can’t go back in until we tell you it’s safe.” That opens a lot of cans of worms that they were not interested in when they were doing their due-diligence process.

So, you know, a second one is that, you know, our clients continue to read the paper, read the news. But whether you’re in Texas, Florida, California, Michigan or in the Northeast, there’s more and more notation of vapor intrusion or legacy environmental issues. You know, this is a sophisticated conversation to have anyway but when you’ve got to do it in a headline fashion, it never comes out good, I can tell you that. So more and more these types of things are hitting the press and gaining traction because a lot of them actually are a real news story as unfortunate that is, but my clients don’t like to normally be in the news, at least not for that.

On the reopener side, meaning we’ve done everything we could possibly do and we’ve arrived at a closure that means my piece of property is worth what it’s meant and everybody’s safe to use it and go forward, the old re-opener component is always a scary one. And it’s a question I get that is hard to answer how to be reopener or proof. Massachusetts being probably one of your current…other than Michigan being, you know, a current one, that’s looking at multiple sites and sending out letters saying, “You know, what we did a screening of, you know, a thousand plus sites that we’ve closed. Now we’re rethinking how we feel about TCE because there’s some changes in the risk dynamics for us to hold that against.” That means we’ve got 200 priority sites where we might send a letter similar to what you have on the right, asking for people to actually go in and take samples or that they may themselves go forward and take samples to demonstrate there is or is not a concern on a piece of property.

So there’ll be a lot that comes out of that effort and again, if you want that scrutiny you want it all in the due diligence phase, so you can make all your business decisions upfront. So that leads you to an element that’s happening now, which is a little bit of changing risk, your poster child for changing risk is TCE, as many on this call are probably familiar with. In 2011, the EPA adjusted its risk criteria. You could do a whole presentation just on the study and some shortcomings that came from that and really how we evaluate risk and how we adjust for modifying factors and things like that. Nonetheless, the EPA was satisfied, it went into IRIS and so it affects all the databases that then stem out of IRIS.

So, in this case, you know, Massachusetts being an early adopter that resulted in the letter that I just showed you. A more recent one, which is kind of the evolution of how these things kind of roll down, is you not only have what I have here in the box, right, this table one is from a 2016, Ohio EPA guidance on specifically when would you need to… If you get these concentrations from TCE, for example…so you’re doing due diligence. You’ve identified maybe there is a industrial operation that actually use TCE, maybe it’s in their waste stream. And so you go and do your investigation, typically soil and groundwater. If you’re in a state that actually has some nuanced guidance on soil gas that may lead you into other media, so either way you may eventually find impact that leads to the next question which is there anything indoor air, say an indoor air sample is taken. Here’s your criteria on the left are your microgram per meter cubed and your more toxicologically driven evaluation format versus parts per billion by volume which is your more generalized, you know, density of a contaminant representation of concentration.

So these concentrations on the left side with the accelerated response action, so if you have these concentrations which are relatively low getting close to what detection limits were, again, five to 10 years ago, that scene is an issue that needs to be fixed within weeks, versus you take it and you’re at 6.3 micrograms per meter cube, for example, in a residential setting. That needs to be fixed in days, versus 20, that needs to be addressed by removing any of the sensitive receptors. So, these are urgent things, this is an acute evaluation, right, so it’s short-term.

The natural thing that comes out, and my reason to emphasize the Ohio one, is that’s one where they’ve actually worked backwards and said, “All right well that’s our indoor air, our consultants are out there taking soil, soil gas, groundwater. What can we do backwards from that?” And so if you want to dive into other pages in this guidance you would note we actually have as low as 11 micrograms per liter, being something that’s a, “Hey, within two weeks you need to address the risk, evaluate the site and address the concern,” versus the 32 micrograms per liter being something that is an urgent.

So, I found that concentration in groundwater, I need to make some urgent decisions about potential receptors above it. Those are numbers I see all the time, so I can only imagine what a ripple impact this will mean and this gives you something that directly ties to a regulator which, for those that are very familiar with the phase one process, right, that decision of, “If I brought this to the attention of a regulator, would they determine if this was of concern or not?” That’s my de minimis line versus my REC line, “I’m gonna go down.” So, in this case, you have numbers in your hand that can relate back to media that may be closed from a time before this guidance document. So changing risk is a big deal so staying ahead of that is a really important thing for any environmental professional that’s on this call.

All right, so there’s a lot of history that happened, and it’s… I don’t want you to read it all on the slide although you probably could faster than I can say it, and I won’t say at all. In general, vapor intrusion and how it fit at least into a regulatory perspective and thereby into a due diligence perspective… If we’re talking about vapor intrusion in the ’80s, ’90s we’re probably talking about methane, maybe radon, depending on where we are in the country. As we move into the ’90s, we at least get introduced to the Johnson-Ettinger model. That makes its way in ’95 into an ASTM standard. So that’s our first place where that lives in a formal recognized manner to make decisions of concern, no concern.

What happened in ’96, again as an observer of history and not somebody involved in that, is that it actually was excluded from the EPA Soil Screening Guides, which then becomes a document that actually informs many state regulatory programs, as well as a few other federal programs. So, it’s absent there, is a unique, you know, point where, “It’s on the books, but we’re gonna leave that out.” There’s a site that probably gets more mentioned than others, so I will mention it here, which is the Redfield Rifle Scopes Site, I have more on that in a second, in Colorado. It plays an important role in vapor intrusion, it kind of actually shows in kind of an almost black and white way that this is a pathway concern that needs to be on the table.

Then from ’99 on, we start to see it included with different documents. The 2002…felt like it was out forever, in draft. ITRC stepping up and actually starting to have some practical guidelines and approaches in 2007, very helpful and really began a conversation of, “Okay, how do we tackle this?” Then fast forward to your ASTM Vapor Intrusion assessment standard which came out in ’08 then later updated to be a vapor encroachment condition standard in ’10 and ’15. There in my red stars your TCE component, that’s only one compound but it’s one of specific interest because it now has an acute risk exposure component, right? So, I mean there’s some motivation to bring that forward. Almost a similar motivation to, “Hey, I found something in the groundwater. I need to look around and see if somebody’s drinking it.” Right, this is the same level that we had in early due diligence and investigation work that we did.

Then the last bunch, I have kind of crammed together. Post 2010, we really started to see things line up and have formal things that we could look at whether it be the vapor intrusion database that was put together by the EPA which gave us a wealth of data to then extrapolate a few things from. Specifically, my little bouncing ball there, right, the attenuation factor. So how much is there by the time it gets to me, how much less will it be? And kind of a little bit black box but sometimes you can climb in the box and update it.

EPA presents us with vapor intrusion screening levels and then by 2015, we actually have our petroleum vapor intrusion guidance and then a more generalized vapor intrusion guidance. So there finally, at least, are things we can point towards in states where maybe the guidance is not very specific. So, there’s a few states that are holdouts. I happen to be talking to you from one of them. It doesn’t mean we don’t look at it, again we’re on that site-by-site basis more here in Texas, than not. But there’s a few others that are kind of rolling right now. I understand from Tom, Georgia’s in the works and on its way shortly. So this is what that journey felt like for those that got to the story late.

So what did that result in? That resulted in a lot of guidance. A lot of it is contradictory but more and more, good standards, good practices seem to be brought forward and the older kind of methodology and things that didn’t play out…because we’ve had study, after study, after study…has led to some really good guidance probably in the last five years for sure. One plug for Tom and for Land Science is I have up at the top, most of these guidance as you see here as well as probably 10 times this can be connected to state specifically on the Land Science website. So it’s worth your time if you are working in multiple states or you just want to confirm, “Hey, has there been an update or a change in an area that I might be going to?” So, now you…I’ll leave it at that. So in those guidance documents and in how we think about due diligence and how we really just think about vapor intrusion in general, this was a very early presentation, right? So, this is New Jersey out in front on this one, way to go Garden State.

So, back in 2005, long ago this was their model they presented, right? So, we had some industry, industry has a release, it’s hit the groundwater table here, illustrated by the triangle that you see, and then obviously the gradient is moving to the right on your screen. And then we have volatilization for the water table. We have diffusion through the vadose zones so above the water table. And in this case, we have a stack effect as well as other things that are preferentially causing it to go into that home.

So, it still is a nice way to think of things and it’s helpful. I put these together only to explain kind of how things have evolved. Now, this is a closer look at what’s going on in that structure, that all our plume was moving towards. This is from ITRC in 2007 so we started to understand we actually have subgrade portions to our homes and if so, is that a commercial as you see on the left, or is that residential as you see on the right? I don’t know why they force the grandparent to live in the basement, that just seems me… Or is it like the greenhouse on the very far right where we actually have slab and we at least have some amount of space or subsurface vadose zone to attenuate the concentrations that are coming at us. That’s an odd depiction of a plume, but there it is nonetheless.

So then that all involves forward until the EPA put out kind of their overarching demonstration of, “Hey, these are the factors that are in play and if you want to understand your conceptual site model better, you might want to think about these things.” Right, so, I’ve got my industry on the far left and we’ve got our release and then we have a couple things going on with that release. Obviously, you know, the actual amount of our source, right, what we call our source strength plays into my understanding of, “How far do I think it should go?” Or, “Should I think it’d be a concern?” That might means I free product like non-aqueous phase liquid that’s shown here. Obviously the closer you get to the coast, you may have a large smear zone that we’re talking about which extends that up and it shortens the amount of area we have to get some attenuation from. Or you may have, something that might move with or contrary to groundwater, depending on what kind of aquitard you have underneath it, right?

So, that’s the release. Beyond that, we actually have the structures themselves. Here you’ve got the depiction of right something at grade, something with a subgrade, something perhaps even with a crawl space. All right, so those are nuances. In due diligence, we’re gonna assume the most conservative of these, right? More specifically, we’re gonna look at the pieces we think we’re gonna play the biggest part of our puzzle here. So the cubeship soil, how much is coming from the subsurface into that structure? We need to assume some conservative values for that. And then for the building itself, how much air is moving through and out, how much dilution, what’s our air exchange rate? All those elements become the biggest part of that story later and there’s more on that later in the presentation.

All right, so I mentioned the Redfield Rifle Scopes Site, not one of mine, this is as a bystander, just somebody who’s looking at different sites and saying, “You know what? This one does stand out historically.” So, on the right I have a depiction of the largest rectangle you see underneath the blue triangle…oh sorry, the blue arrow there, right? That’s where the site is and as you can see here, in green, I’ve depicted its impact to the neighborhood in groundwater. And so around…it’s got a very lengthy plume here, we can talk about plume lengths in a minute too, but that’s where groundwater was known that’s where the impact was.

On the actual left of that it’s kind of a zoom into that box as seen and so I’ve got, you know, the 1, 1-DCE, PCE, TCE, 1, 1, 1-TCA common compounds that have a vapor intrusion story today, less so then. And so these are the concentrations you’ve had. These are not, blow you away numbers. There certainly are higher impacts on the site itself but further away those obviously diminish. Now, down the bottom left, I chose Texas and Louisiana only because Texas doesn’t have hard and fast rules like prescriptive lookup values that are vapor intrusion based and Louisiana does. And then on the far right, I have your vapor intrusion screening level, so as I go from left to right I have two. The groundwater sub ING is my, “How much is in groundwater based on me drinking it?”

And then I have the groundwater inhalation of volatiles to the right of that and then the groundwater and closed structure non-industrial is the Louisiana based numbers, starting with the 18,000 for the DCE and then of course the vapor intrusion screening level that we all know and love today and use in our due diligence, hopefully. In Texas, we have a tool known as an MSD, similar to a ground water use restrictions. It could be something that’s putting in place by, you know, a city itself. Another entity could put it in place but this allows us in Texas for example so I can remove that pathway, so that’s my reason to put the MSD on top of it. That would mean my next lowest concentration to compare would be the groundwater inhalation of volatiles, INH-V. So you can see a huge jump in the numbers. I only use this to illustrate how prescriptive numbers that we are given in our due diligence process may or may not include vapor intrusion.

Now, Louisiana to the right of that you can see definitely much lower concentrations are acceptable for that enclosed structure. This actually is based on a Johnson-Ettinger model. Regardless, jumping to the vapor intrusion screening level, you can see even lower numbers in groundwater would drive those 200, 58, 5.2, so I would compare those so we’d exceed at that 810, we’d be right at it with the 58 that I have circled. And then we would be exceeding it with the 41 but not with the 1, 1, 1-TCA, 7400. So, today we would screen in some but we wouldn’t screen in that many, we’d start to get lower concentrations as you head north on this map you see in white.

So, that said, we should have some vapor intrusion suspected but it shouldn’t be all over the place. So what happened, when in 2007 this site in the process of addressing its release and pursuing regulatory closure, went in and actually sampled inside homes. So, if you see something other than green, right, so you see purple, you see yellow and you see blue, you’ve had an exceedance. And one thing I like in this map is this a great example of it following the plume, right? So, I can definitely have internal sources that are biasing my data but my chances of having it match my plume and go through here, highly unlikely.

So, this was a poster child of…not only is it real some of our screening criteria even that we would use today may not always catch it. And I’ll go back to the prior slide only because at the very top is some of your reasoning for that, right? So we actually have highly porous soil underneath this whole area, so most of the models that we would use to screen don’t use that. They actually use a soil type. And then we kind of branching all the way up to sand, not up to gravel or boulders or cobbles. So, the larger and more coarse the material, of course the more room we’re gonna have for vapor to come up to.

Now, one of the good thing is that there are an area where this can be modified and addressed and so if you remember the kind of basic side to that plume, this is what it looks like when I actually did post mitigation sampling. So it can be addressed, there are solutions to these, they don’t have to be super expensive. I say that not as somebody who had to pay the bill though. I did look just to see if there was an update and so there is no… I think to date, right, there’s a whole lot going on with the source area that we spoke about. Another 381 homes that have ventilation systems, already 187 have been cleared. And so this is not meant to be a forever thing. If you can address the source and stop feeding but this moves us from due diligence into kind of remedial and mitigation steps, which we’ll talk about a little later.

All right, a take-home from these area studies, background concentrations might be higher if you’re using very low levels. The 2011 risk criteria and there’s a lot of sources for indoor impacts because I’ve seen many studies where they get confused by their data and they keep going back and back and it doesn’t repeat. Sometimes, it turns out there’s an interior source. So, in the phase one process, which is where most due diligence is gonna have where the rubber meets the road, right, you’re looking for the hazardous substances or petroleum products. Is it under there an addictive manner that it might be a release or is there material threat of release. If so, that’s simple, right?

We arrive at our REC, it could be from the gas station, the dry cleaner, whatever operation that you see solvents or fuels that we are concerned about, might be metals, might be other things. If it’s not, not an REC. Beyond that, does the release present a threat to human health in the environment? Would it be subject to enforcement? This is why the regulatory mindset for where you are and where the site would sit is a big piece of that. It may be de minimis to a lot of people. Has it been released? If not then that would be an REC. If it has been released and it has no activities limitations and it’s a historical REC versus a controlled REC where there might be a control in place, then it’s safe now.

The point at which you may find vapor intrusion and the environmental professional needs to make the opinion can be each of these. So a CREC may be an REC for a different reason now. An REC can be arrived at perhaps beyond that de minimis component now. But either way, you have to put it in context for the site, its use and even though we have no crystal ball, perhaps what the concern would be if brought to a regulator under the right use concerns.

So, in due diligence typically we have early steps like the phase one, we may even have site characterization, where we go out and collect some samples and then we evaluate. If there’s future structures, we evaluate that one way, if there’s current structures we might evaluate those a different way. I do have more on the future structure, existing structure and I’ll give a plug for that in a minute. But you can jump from these right to the mitigation, right? So that mitigation could be…address the source, build a barrier that actually prevents contact as most of you if you’ve taken any toxicology or risk classes, risk equals toxicity times exposure. You can address the toxicity or you can address this exposure. Sometimes we do a balance of the two.

So, in part of due diligence if we want to still step out from the ASTM standard, a lot of what we talk about has to do with distance, right? I don’t care if there is a dry cleaner that even if it has had a release, if it’s moving a direction that it just can’t get to me, that might be a concern to somebody else but it won’t be to my site. Now that requires a few pieces of information. If I don’t have those pieces of information, then I have to assume I’m either cross gradient perhaps or maybe I am up gradient. I need to know more about what I think is coming at me and how long those plumes might be. So, since that’s part of the ASTM standard kind of built in to your REC evaluation but more so with the E 2600 I’ll talk about in a second, knowing length of plumes is actually pretty valuable.

So, there are several studies and sometimes they’re contradictory. An API one you see on the top would present the majority of plumes being within that 200 to 300-foot length. I still think that 300’s not a bad number. There are other studies which show a median level, right, so in the middle of that curve are closer to 500-plus feet. A California criteria for evaluating plumes, this is all petroleum, I’ve got it written on top, put your average at 198 going down to 5 micrograms per liter versus four TPH and then an MTBE may actually be. And then the 90th percentile gets you closer to that 500 feet and then full plume lengths for like a maximum one that they saw will be substantially larger but understanding what that plume is kind of helps with that storyline.

I’ve put this in here only to emphasize if I was doing due diligence and looking at something I didn’t have a reason to rule out I was down gradient from, I would wanna be judging more by the 90th percentile maybe not the max unless you felt there was something different about that specific site. But that gets you closer to 200, 300, even more feet and actually some of the studies that we’re done as you see on the far right. So that said there’s a petroleum number the ASTM puts out and I’ll show that in a second.

So, let’s talk chlorinated, right, so your medium plume lengths, these were developed by as you see go into a model known as BIOCHLOR. They’re from, you know, a good representation of the United States as you can see on the top. Here I’d be looking at that 75th percentile, wouldn’t go to the maximum, but this gives you some comfort level of plume length. So, the chlorinated easily over a thousand, is where I would start and then some as long as 2000 depending on specific information.

So kind of put together, some of your biggest factors in judging a plume really should be source strength. Is it from one tank on a site that was 500 gallons that’s more than 500 feet away? I feel pretty comfortable. If it is an industrial facility with tens of thousands of gallons and it’s subgrade and the groundwater velocity is anticipated, because of the soil conditions, that’d actually be relatively high, right? Then I might extend my distance before I get comfortable. On the right side, you have some depiction of not only length but a little bit of width that came from a study where 400 were sent in and put together so you had high and low but they kind of averaged out and this is what you see.

On the left side, on the bottom, however, is kind of a contradictory one. Now that study had, you know, greater than 100 but you have chlorinated plume lengths that are easily in the 90th percentile closing in on 6,000. So, getting you a “good enough” from that one becomes hard. There’s a whole lot of differentiation that needs to happen because it turns out there are small sites with low source strength that happen to be in places that have low groundwater velocity and then there’s the contrary.

So, I would always judge using the higher end for my screening and then let the data actually dictate if I want to back off from that. So, from ASTM standpoint, we’ve got the phase one standard that now mentions vapor migration within your REC, CREC definition. You’ve got the vapor encroachment screening criteria which gives you a search distance called their Tier One Criteria, right? So that was lateral we were just looking at, so 528 feet, 1,760 feet, so you can see some basis for those. You can adjust those critical distances, using the things like we just went through.

For the vapor encroachment, they actually also include a vertical, I say lateral here but its vertical, distance of 30 and a 100 for your chlorinated and then your petroleum. ITRC gives you an inclusion zone also of 30 feet, a separation distance of five feet, 18 feet for different types of plumes as you go vertical. So, a lot of that requires you have information in front of you, you can make these decisions so keep that in mind. Oops, backwards, all right.

So, one of the thing I wanted to emphasize in the world of chlorinated versus petroleum plumes in environmental due diligence is the understanding of the risk components that go with it. “Yes, there’s been a release, yes it’s gonna migrate as it would normally in the environment.” The chlorinateds, not only do they go so far, unfortunately they don’t have a lot of attenuation on their way up to you as well. So, if I was gonna compare on the left, the petroleum vapor intrusion PVI, right, so non-chlorinated probably benzene is your best example, that will be light non-aqueous phase liquid, very rapid in general, that there’ll be aerobic degradation on its way up so it usually has lower vapor intrusion potential. So, I’ve gotta be closer to the concern for my vapor intrusion issues to be my top thing, probably. Versus on the chlorinated side, vapor intrusion potential is high. Why? Because there’s very limited attenuation of most of the chlorinated compounds as they’re going to be coming up towards you.

To that end, prior, most petroleum vapor intrusion concerns are gonna happen within the majority of the gasoline range that you see there in yellow. Aviation fuel if you happen to be doing a site that has that, there’s part of the abgas falls right in there as well. To a lesser degree, you’re gonna have Jp4, but you can see diesel, just very limited in what it can actually touch. Then there’s a depiction of the amount of oxygen as these VOCs are coming up and obviously that plays a big role in the attenuation.

So EPA has given us some screening guides for vertical, they also mention some for lateral. I’m trying to be mindful of my time here. So that said, this at least gives you some criteria if you’re dealing with a site that’s got maybe a prior closure or maybe it’s an adjacent site that you pulled the file for and you’re worried about a lateral component, right? So, there’s not really a lateral component issue in the EPA criteria. However, there is a, at least a presentation that way. You know, you can use the same criteria laterally as you do vertically provided you actually have separation. So, we actually have a data point that is suggesting that there’s not a concern.

So, for example, you may be dealing with a site like we have on the left, where I’ve only got these four wells. At least I have some groundwater flow information that can actually help me in my critical distances, like on the top. If I wanted to look for clean wells, if I wanted to factor in groundwater flow as I see in the bottom, so if I was trying to make a judgment for these one, two, three, four homes that are to the west as to if there was a concern, if it was me, if I was gonna look at those homes right there, I probably would still need a well to make a decision if something’s moved or not. Because there’s a limited amount of data for part of this site and the abandoned tank, as depicted here, right, is on the western side of their understanding of the site. And there is some Southwest, I guess South if I’m looking at the North arrow movement, that could impact one of those four homes.

For some of you, in your due diligence process you actually have a vapor intrusion screening criteria. Again, New Jersey out in front perhaps, right, so you can start with an actual flow through chart and say, “I’ll start here, is there a trigger, or is there not a trigger?” And I move through, so you have specific numbers to look at and you actually have distances. So, when you’re doing due diligence in areas where there’s been a process laid out for you, it makes it easier. If you screen in, then go get some data.

Now, most of us on this call in your due diligence process, there’s gonna be a point where you’ve got to go and you’ve got to pull some files and you’re using data to help make a screening possible. Maybe it’s within that search distance and so now you’re trying to make that decision. So I’ve depicted in the top left there’s there industry again. In the bottom right is perhaps the property that our client is interested in acquiring. So, is there data? Is that impact actually delineated? These things all factor into the story. So sometimes you’ll get numbers hopefully, of a specific chemical concern that you have. Even better yet, if you’ll get a plume I will be mindful and suggest you do the same. If the groundwater plume is incredibly well behaved and it doesn’t cross lines but there’s an absence of data to suggest that, you may wanna rethink if you’re gonna be totally comfortable that there is, “Yes, it’s delineating, yes it’s closed.” So, for those that believe groundwater will stop at a fence line, news alert, sometimes it doesn’t, right? So knowing groundwater flow then should influence is it coming at you or not, so in this one right I think I probably need additional data, depending on what that risk criteria was.

So to kind of summarize what we just went through, I’ve got my industry, I’ve got my house again, perhaps there’s been a spill. Right, the spill’s impacted soil to some extent, groundwater to some extent. Do we have data? I would love to have a data between us and that release. If so, right, then I can judge it against some risk criteria, like groundwater is either non-detect or it’s below whatever that risk criteria is that you’re using state-based or federal-based, if you have an absence of state-based criteria, right?

So what is that distance then you can make a decision, I’m good or not good. The assumption that goes along with that is that soil gas should also be limited, right? There’s only so much mass exists, so second piece of that is, okay, well vertically maybe it’s made it over to me. I’ve got my concentrations in groundwater, not unlike the one generalized one we just did. And so I need to know a little more about our distance. And that distance is also helping me make a determination. Is the soil gas that will be present within the vadose zone gonna be enough that it can get to the home itself? And so off to the right, I have some of the criteria that comes from above, that we talked about.

So judging that allows you to make some screening in or out decisions. You should end up…now this one’s for petroleum, but it’s still general. Either you have on the far-left scenario, there’s something down there but it’s not enough to present a concern for me. Either because the compound’s not toxic enough, or the properties in which…physical properties of the site I’m looking at don’t allow it. You may hit the middle ground, that there’s a potential for it, and you need to make a decision, “Do I need data to actually answer that question?” In the absence of data it may remain an REC. The third one is you could run into that emergency situation, either during your sampling or as we saw in that Ohio 1996 guidance document, you could have numbers that are in place that it’s not a burning building but, you know, it’s hard to make things exciting in the environmental industry. So, there you go.

Modeling played a bigger role before but as I mentioned the Johnson-Ettinger model is a tool. California has an updated component. As you would guess, New Jersey does too. It can be modified to meet state goals or risk based corrective action criteria, can adjust for soil properties. I will say that the 2004 Excel that the EPA put out was taken off their website in 2015. So that’s suggestive that maybe messing with the black box is not desirable for everybody unless it’s being done under the scrutiny or in consultation with the regulator, perhaps. But either way you could end up with, at least, numbers you can work backwards from.

Now, I caution all those things we just went through, which are all screening based is if you believe there are preferential pathways, right, then that attenuation we were just talking about, that happens from there before it gets to me, may be different. So you got to understand the release itself, the guidance you’re gonna be looking under, site utilities, site lithology, and then underground water. So, under all those things if you can’t use those to make your decisions that you had before as your normal tools and this now tells you, you know, what all those things that are the assumptions that were based on actually are not currently true from my side, you may need to screen it in.

All right, to kind of wrap up, hopefully Tom won’t be mad at me too much. So I’ve had Nixon up at the top right only because he loved good investigations as you guys know. So investigations are what we might screen in and then head towards next. Our next pools would be your soil gas components, right? So that might be a soil gas monitor point which is kind of here at Modern we use as other names, vapor points whatever you like. Sub-slab if you have an existing structure. If you can do air sampling, there’s lots of nuance to doing time-weighted indoor sampling or getting multiple point samples.

Doing control building pressure testing, we see more and more of that. You need to have the ability to actually monitor real time in the field and move around and find sources, but it’s a great and helpful tool. If you really feel you have a problem that needs to be addressed, you get into the burning building scenario we just looked at. But each of those investigation efforts needs to start with your conceptual site model being well understood.

So with that on the mitigation front, just as a preface… Right, so if I look at it, I may adjust the HVAC system when possible, again a regulator conversation likely happens there. I will begin looking at barriers, spray applied, you can use poly based ones. If you have a lot of penetrations, not my favorite, you can use collection systems usually in tandem with and make it active or passive. Depressurization, pressurization less common these days but void space design in your building and you can do air exchange rates, some more temporary things, with HVAC. On the right, you just have some basic design elements. This is an apartment complex that we here at Modern did and there’s an example at the bottom right of smoke testing. And we were doing that in that process of doing the inspections and obviously you can see, there’s a leak in that one.

So, final thought, planning’s key, marketplace is gonna ask for vapor intrusion in your discussions, so be ready. Default screening is conservative but you have to know if your site meets those assumptions. We use generic attenuation factors such as the vapor intrusion screening levels. Mostly I will find them to over predict. There are certain compounds that will screen in under that that may actually have more attenuation on the way up because oxygen is actually a helpful. Aerobic degradation is actually anticipated. And then mitigation efforts in future design is probably our best way to stay away from those reopener or stay away from those liability concerns that we talked about earlier. Either way it’s gonna be a big part of the story going forward and it’s already a part of due diligence that’s probably affecting all of you, or you wouldn’t be on this call. Tom, how’d I do? I’m over, I’m probably. All right, I think we’re switching here. Thanks again to everybody for sitting through that.

Thomas: Thanks Ken, I appreciate it.

Dr. Tramm: You bet.

Thomas: So, for essence of time, folks, I will be going through my slides and if we have time at the end of this for questions, feel free to chime in but realize with the essence of time, we may just have to get back with you afterwards. So with that, I’m gonna get going into this. So, what is vapor intrusion mitigation? Most of you probably do know what the concept of vapor intrusion mitigation is. It’s the actual physical implementation of a vapor barrier or sub-slab ventilation system into a vapor, into a building structure itself.

And not to be confused with an SVE system and many times I’ve been involved with where consultants have designed SVE systems of source areas outside of the building. And that is not truly a vapor mitigation system. It has to be implemented with the building structure itself. What options do you have with vapor intrusion? Well, you can collect sufficient subsurface and indoor data to provide that there’s no risk, make a science project out of you, if you will. You can also do a preemptive mitigation, which is what we’re seeing across the nation as Ken alluded to briefly, we’re seeing more and more where they’re just going to the preemptive aspects.

Why pre-emptive mitigation? Well, it’s quite a few different drivers and what’s gaining traction is the fact that regulators are starting to build that into their updated guidances where they’re giving them a route to go right to vapor mitigation with very little information, sometimes just information on their phase one and historical RECs, RECs what not. But also, what we’re also seeing is the financial lending institutes are pushing this a little bit further as far as understanding that their liability risk is on hand too with potentially having the property fall back to them on a bad note.

And then larger corporations, nobody wants to be the ExxonMobil, nobody wants to be thinking of oil-filled ducks. Same thought process with vapor intrusion, it’s such a leading concept in the environmental world now that they don’t want to be having an ill-blended concept. So they’re taking an opportunity to just put in a mitigation system to reduce their liability and overall, still protect the property which is the main concern.

So, really quick, we’re leading experts of vapor intrusion mitigation. This is a few emblems of who we’re working with this State of Michigan, CalEPA, U.S. EPA. Ultimately what we’re doing is we’re providing our barrier information to them but we’re also giving them real-world hands-on boots-on-the-ground information, so that they can build into their documents. And as Ken also gave a plug to us, you can see a plug here, this is our Land Science website for the resources.

If you’re not familiar with our new website, we released a little less than a year ago, I encourage you guys to go to our website and check it out especially the resource links. We keep it updated to where you can go there. Let’s say you’re a consultant in New Jersey and all of a sudden, you’ve got a project in Mississippi and you don’t know what’s going on in their vapor intrusion world, you can go to our website. We have a state-by-state guidance list and if there is a guidance, it’s updated, and it’ll send it to you directly. Because we all know the state websites sometimes they’re very hard to traverse, so we’ve taken that opportunity for you guys, to be able to give that link to it.

So if you haven’t bookmarked that, I encourage you to do because it will benefit you in future projects. So, you know, the questions are what are the most recent regulations? What about short-term TCE? You know, that’s the benefit of having these resources, understanding that if you hear of it at a conference or on a webinar, “Hey, I just heard about an acute concept in TCE. I’m not familiar with that.” Well, we can have a one-stop shop for you guys, so you can go there and read all about what’s the information related to the short-term TCE. What’s going on in the different states? What has ITRC done recently? What is ASTM, etc.?

So, vapor intrusion mitigation options, are there a lot of options? Absolutely. Ken touched base on a few of them. Void space,
building pressurization, active venting, sub-slab depressurization, passive venting, barriers, user vapor intrusion. Void space, if you’re not familiar with this picture, it’s actually what they call Cupolux. It was design not for vapor mitigation, it was designed for construction matter to decrease the concept of what kind of subgrade could that be, it was actually designed in Italy. A lot of times we design things for one purpose and turns into another so, you know, Cupolux has been something that’s been coming a little bit more in the United States, more so in Canada. It’s definitely a benefit, it’s gonna help especially if you’re designing active systems, can reduce the size of the ventilation fan. It can reduce actually imported fill.

But realize every system, every type of design you’re gonna work to, you’re gonna have potential limitations, everything has limitations. Decisions to mitigate need to be made early on this, so what I mean by that is, you can’t just say at the 11th hour, “Oh, we’re gonna throw this Cupolux in there.” Because they have to…the architect, the civil engineers, they all have to understand the process ahead of time. In a lot of times, still here in the United States it’s outside of the general contractor. That’s what I mean by GC there, general contractors comfort zone.

And what I have lesson-learned and I’ve lived it, is it can be an expensive alternative to an active system. Now some of you might scratch your head and say, “Well, wait a minute, what I’ve heard, if you have heard of Cupolux, it’s pretty cheap.” Correct per square foot it is, however, the other aspects of concrete foundation design etc. can increase. Because the actual concrete placement may be a different method and therefore if you’re talking about a large building envelope that different method could increase exponentially for the concrete placement itself.

Now building pressurization, if some of you guys are on the webinar here with Michigan you probably are familiar with this picture, this is the Pontiac Silverdome. I always put this in here as kind of a joke because I was originally from Michigan. And I say after the Lions got done losing all those years in a row that’s what happened to it, at the top picture, it’s just deflated. But joking aside, what we’re looking at here is the building pressurization. Can all buildings be pressurized? Absolutely not, but if you can could that be a positive solution? Sure. But you need to understand, there are still limitations to that too. When the HVAC is off or if you have electricity power blackout like we did, well, you’re not gonna have any positive pressurization to the building and now you have envelopes of exposure concerns and the cost of electricity. Think of the cost of electricity just to blow that big old building up.

But also, I’ve seen systems where they design where a building pressurization would be on that, or they propose that, I should say, on a convenience store. Well, let’s think about that. How many times is that front door opening in and out? Unless they have a set of doors like you do at like hotels, probably not the best solution. So, again, limitations to everything when you’re thinking through these. Active ventilation. Quite a few of you are probably saying, “Yeah that’s my first thought when I think of mitigation systems.” Okay, absolutely it’s gonna be a good part, I have a picture here of a radon system and inline fan. And then also the actual picture, the photograph, is vents that are actively drawing from the rooftop.

You’re gonna have a lot of benefits for active venting. However, same thing, it’s an electrical concept so if you have a power failure, you have a concern. I lived through a lesson-learned on a project in Indiana where they kept wondering why they kept getting TCE hits inside the building within a few days after they just checked the system and it was operating. Well, it turns out that the homeowners didn’t like the noise of the fan and every time the people would come they’d turn the fan on because they knew they were supposed to be doing it and then when they’d leave they’d turn it back off, not really caring that the concept…that they were potentially being exposed and actually were being exposed to TCE. So you do have some limitations. What…one of the benefit on active systems is, is really when you combine it with the actual vapor barrier itself.

Passive venting, well that’s really where we need to push along, a lot of times passive venting systems are gonna be your one stop discussion as far as creating a preferential pathway underneath that barrier. It’s not to be confused as a be-all-end-all venting system. It’s to create a preferential pathway. Yes, you want to get an ROI, radius of influence, underneath that building structure and ultimately this is combined with a vapor barrier. But you also want to understand that this is passively vented. Now some people may argue when you see in this picture here a wind turbine that that is not passive, it’s almost semi-active. Most states that we work in and regulators that we work through concur that this is still passive, it’s just a wind-driven turbine that creates a CFM in a draw so that you can appropriate the draw from underneath. In the pictures, you’ll see that there’s a vapor vent here connected to this as well and I’m gonna get into that in the next slide.

So vapor vent, quite a few you’re probably familiar with it but the vapor vent is a low profile. It’s a opportunity to place it in lieu of PVC pipe. It can be installed in shallow subgrade 406 introduced. Subgrade itself which ultimately reduces install costs. The vapor vent can install to passively or active but understand if you’re gonna design it actively, communicate with Land Science and we’ll help you through it because there is a different head loss concept to calculate. And we’ll work through that with your engineers and your scientists to make sure that you guys are designing it appropriately.

Now, sub-slab vapor barriers, there’s a lot of them out there. There’s HDPE Geomembranes, Spray-Applied Asphalt, Composite vapor barriers, and vapor barrier coatings. Where does this all line up? Well, before they started putting in vapor barrier contaminant vapor barrier thicknesses, it was all over the board. Unfortunately, in some states it still is, but what we’ve noticed is in more and more than just a few of them. What you’re seeing is the federal, the states they’re putting in a minimum contaminant vapor barrier thickness.

And I put in here an actual little cutout from the EPA where this is their language, sheet membranes less than 30 mil are not durable enough to prevent significant damage. Now, that’s not the only reason. There’s also a diffusion concept there and the degradation concept that you don’t want to have those chemical degrade, over time, the barrier itself. So that’s why you want to have the appropriate thicknesses.

Here’s a moisture barrier. A lot of times when you’re designing systems or you’re getting involved in the 10th hour if you will, sometimes they’ll say, “I already have a contaminant vapor barrier, we’re good to go.” Well, do you? Because a lot of times it just says a vapor barrier and it’s just a moisture barrier. As you can see here, it’s very thin and it’s usually duct-taped together on the utility penetrations and seaming a barrier itself together. HDPE or HDPE high density polyethylene Geomembranes very durable, chemical resistant, had a long-time history in landfills, still does with pond lining, landfill lining.

But what we’re also dealing with here is understanding that it has major limitations when you’re putting it in the building. Why? Well, think of your garbage can when you go home tonight and think of that plastic, now imagine a taking that plastic and trying to bend that around a utility pipe or bending that around the foundation, pretty difficult. Not saying it can’t be done, you can see here they’re welding it there on the bottom picture but you don’t have to understand that. If you have a site whether it’s a multi-use or a residential and you have a ton of penetrations, a ton of bathrooms, probably not your best solution then, designing with an HDPE Geomembrane.

Now your next is a spray-applied Asphalt latex membrane. That was actually born here in Southern California in the LA region. And it was because of the methane concerns they’ve had here in the LA for a long time. And when they noticed it, that they had to understand a quick solution, knowing HDPE wasn’t gonna be a solution. Nope, because you can see here, look at these penetrations coming up like this, gentlemen. Those penetrations need to be easily bonded and they’ve got to move, move, move. So out came the Asphalt latex membranes.

Constructability, yeah, easy to work through, however, chemical resistance when you’re dealing with chlorinateds or your other VOCs specifically chlorinated, it’s not chemically resistant, and over time it’s gonna adsorb to that and degrade that actual barrier itself. So, what you’re seeing here is they’re actually just spray applying the Asphalt to a geofabric. Which then leads me to a composite membrane. That’s the blending of both worlds. You saw some positives on some of those. Well, you can take the positives and put them together, right? So, that’s what we did here at Land Science with Geo-Seals. We took the durability of HDPE, the chemical resistance and the constructability of the spray applied and we brought them together in a sandwich type concept. We’ve got our first U.S. patent, multiple regulatory agency approvals in many of the states, in all 48 states I should say and the ones I actually have a vapor intrusion guidance’s in teams.

But also, the last point here, you’ll see here, is the diffusion coefficient of 685 times lower diffusivity. What I’m getting at there, not to bore you, is basically just think that 685 times less of those TC, PC molecules are gonna get through the barrier itself. Ultimately, if you put in any type of modeling system it’s showing you that nothing will be breaking through. And we’ve tested it on a pure solution of TCE and benzene and it does not break through on…over a period of time.

The other thing I want you guys to take home from this today though, is a vapor barrier system with a warranty. If you’re in the middle of this or you’re getting brought into a site or you’re in the beginning of a site and you’re thinking about a vapor barrier, one of your first questions should be, “Does the system have a warranty?” And if not, why? Maybe that’s something you need to re-ask whoever else you’re talking to as a provider. Because warranty is huge so you have to look at this concept of what type of warranties are offered. Sometimes they’ll say, “Yeah, we offer a one-year material.” Wonderful, but if it’s for a building that’s gonna be there for 30 years, is that really something that’s gonna be beneficial because now it’s underneath the building and you have one year warranty.

Here at Land Science, we offer up to 20, 30-year material warranty. System warranties, as you can see here, little asterisks below provided on a site-specific basis. If you provide us the data information and site-specific information and request the priors installation reports and whatnot we can offer the system warranties up to the 20-year too. So, talk to us on this and this is on Geo-Seal Electrical, we do offer a one year because it is a wearable surface. And I’ll get into those barriers here in a second.

QA/QC measures, it’s important and understand that if you don’t have a QA/QC thought process in place, it should be when these barriers are being put in. Certified applicator network here at Land Science, we took the opportunity. There’s no standard training for any type of barrier installation, so if you’ve got another type of barrier you’re considering, another question you should ask is, “Do they understand how to put this in, what’s their background? Maybe they’re great in HDPE, putting it in ponds and in landfills but have they ever put in HDPE liner inside of a building?” It’s a huge difference.

So here at Land Science we put our applicators through a rigorous certified program to make sure they understand how to put the barriers in, we walk through that with them and we keep an annual training process with them as well. You ever ask that, where we learned and lesson-learned in the role, is we brought an opportunity for a third-party inspector training and certification. Not saying that if you design this you can’t be the certified inspector too but a lot of times they want a third-party inspector and sometimes we’ll request it depending on the site and where it’s located. We want somebody to oversee that. And that inspector training is walking you through what are you looking for, how are you understanding that this barrier is put in correctly by that applicator? Was it thick enough? Is it tight enough, what not?

So the thickness verification here, if you can see this picture it’s a caliper-measuring coupon and the coupon is actually cutting the barrier itself. I know it seems counter intuitive, you put a barrier and that’s vapor intrusion barrier and now you’re cutting it. But what you do is you cut a three by three-inch coupon out, measure it to make sure that you have a 60-mil thickness. And that’s the appropriate thickness that you should have in the spray applied. And then verify that that thickness is appropriate.

You do this and some guidance’s actually out there will dictate how many square feet of a building you should actually take a coupon sample. And some don’t. We recommend if you start as a good reference of every 500 square feet, however, let’s put common sense cap on for a second, if you have an 800,000-square foot warehouse and you’re cutting a coupon every 500 square feet, you need to reconsider that. And talk with us on it, because we can help walk you through those stages.

The last other thing we wanna talk about is understanding smoke tests. In essence of time I’m gonna cut this out there, with concept of discussing too much of it, but understand that we pump smoke…or we shouldn’t, I shouldn’t say we do. But our applicators pump smoke underneath the barrier, looking for any imperfections and then they can repair that during the installation. So, last and I’ll get through this as quick as I can, the Retro-Coat is a highly chemical resistant coating that can be on existing building. So Retro-Fit if you’re thinking Retro-Fit, Retro-Coat same kind of concept, thought process. It’s retro-fitting the building, we can be customizable so it doesn’t necessarily have to be a white floor, we can do a multi fleck look, we can do a slip resistant. Work with us on that.

We’ve also done our calculated diffusion rates on PCE and TCE and understand, here’s our rates below. Basically if you put those into it and that’s on a pure solution, you’re not gonna get a breakthrough. Electrical process, so you’ve got the surface prep here that’s important. You see the gentleman here with a shot blaster? If you’re not familiar it’s actually shooting beads or steel balls into the concrete to scarify the concrete. Why we’re doing that? You want to create a profile that concrete, remove any residual on top of that concrete and allow that opportunity to create the perfect bonding opportunity for the primer. Before you do that you want to also treat the cracks expansion joints in preparing the concrete and seal any penetration with the caulking material because then you can be prepared to put your six-mil primer.

I say six mil primer but that’s done on the basis of that you’ve done your moisture tests. We recommend a calcium chloride test on that concrete and then verify what that moisture of that concrete is, because concrete is still porous, it’s still gonna hold some moisture. We need to know that to make sure we have the appropriate primer. The Retro-coat will go on as a 20 mil on 210 mil applications. Here’s a finished Retro-coat so like I said, it doesn’t have to be an ugly floor. This is Retro-coat here that’s Retro-coat there and it’s a finished floor over in the San Francisco Bay Area.

So we can work through the process and understand that this is your be-all, end-all barrier. It’s a wear resistant too, you’re looking forklift traffic. We can put in a demarcation color underneath if you have to have a discussion with your regulator of how do you know when it’s gonna wear down but, you know, ultimately this barrier is your be-all end-all for, a lot of the existing buildings and it’s taken off across the nation. We are seeing tons of projects across the nation.

And here, this is my last slide I wanted to reiterate that we’re gonna have another continued webinar coming up in May, so look for that in some emails coming up. And what I want you to understand is that’s gonna also talk about more vapor intrusion investigation and also mitigation, some successful case studies and so I’ll talk about some details maybe in your neck of the woods as well. Here’s also my contact information. With that, I will turn it back over Dane. Thank you.

Dane: All right. Thank you so much Tom. That is gonna conclude our presentation, just a couple of real quick reminders. First, you are going to receive a follow-up email with a brief survey. We really do appreciate your feedback, so please take a minute to let us know how we did. Also, you will receive a link to the recording of this webinar as soon as it is available. We are out of time so if you asked any questions, don’t worry, someone will follow up with you with an answer to your question.

If you need immediate assistance with a vapor intrusion solution from Land Science, please visit landsciencetech.com to find your local representative and they will be happy to speak with you. And for more information about environmental services from Modern Geosciences, you can visit moderngeosciences.com. Thanks again very much to our presenters Dr. Kenneth Tramm and Thomas Szocinski and thank you to everyone who could join us. Have a great day.