Update on The Evolving Vapor Intrusion Regulatory Landscape

Dane: Hello and welcome everyone. My name is Dane Menke. I am the digital marketing manager here at REGENESIS and 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. If the webinar or audio quality degrades, please disconnect and repeat the original login steps to rejoin the webcast. If you have a question, we encourage you to ask it using the question feature located on the webinar panel. We’ll collect your questions and do our best to answer them at the end of the presentation. If we don’t address your question within the time permitting, we’ll make an effort to follow up with you after the webinar.

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 provide an update on the evolving vapor intrusion regulatory landscape.

So with that, I’d like to introduce our presenters for today. We are pleased to have with us Dr. Sigrida Reinis, associate at Langan. Dr. Reinis has over 25 years of consulting and academic experience in the areas of construction, engineering and management as well as environmental engineering. She leads the vapor intrusion mitigation practice at Langan in California. Dr. Reinis has designed vapor mitigation systems for new structures to be located on closed landfills and brownfields redevelopment sites as well as for existing structures on sites undergoing remediation. She has expertise in the areas of decision analysis, probabilistic performance assessment and cost estimating and project risk management.

We’re also pleased to have with us today, Rick Gillespie, senior vice president of North America for REGENESIS and Land Science. Mr. Gillespie directs a team of technical sales consultants and engineers across North America providing industry-leading support to REGENESIS and Land Science customers. He has over 20 years of experience in the environmental remediation industry. All right. So that concludes our introduction. So now I will hand things over to Dr. Sigrida Reinis to get us started.

Dr. Reinis: All right. Thank you. Thanks for the introduction and thank you very much to REGENESIS and Land Science for this opportunity to provide this brief presentation. So I’ve been asked to talk about recent developments in vapor intrusion and specifically in that nexus of regulation, mitigation and monitoring. Sorry about that. To give you an idea of where we are going today, I’ll go through a quick intro, but just to start off with, I wanted to say that this webinar is sponsored by REGENESIS and Land Science. I just wanted to say, I’ll be talking about a variety of projects where a variety of venting and vapor barrier membrane products have been utilized. But what I will say is that on those projects where a Retro-Coat specifically was used or is being contemplated that’s been noted in this presentation, and throughout this presentation presents professional opinions, observations, experiences.

And I just wanted to emphasize that every site and every project is unique and therefore, you know, opinions might differ, might vary and certainly regulatory requirements vary from one jurisdiction to another. And also lastly, just wanted to point out that all of the projects that are discussed in this presentation are truly still works in progress. So again, even their opinions or views might change if new information or new data comes to light. So in terms of topics addressed, we’ve got to start off with, I’ll just do a hopefully quick run-through, some recent changes in federal regulation and then a couple that applies specifically to the San Francisco Bay area. And then I’ll do that fairly quickly because I wanna focus most of my time on the two case studies. And then kind of hopefully end up on a kind of a looking forward note.

So this is now going back to 2014, so it’s not that recent, but it’s definitely affecting projects that we’re currently working on. And that is back in July of 2014, US EPA came out with their Accelerated Response Action Levels and Urgent Response Action Levels, specifically for TCE in indoor air from subsurface vapor intrusion. And the idea here is that the accelerated response action needs to be taken if TCE levels are detected at predetermined levels. And those actions need to be done within like a few weeks type of timeframe, whereas if the concentrations are higher and reached the urgent response action level, the response needs to occur literally within a few days. And furthermore, temporary relocation might be required, especially for women of reproductive age that have been exposed or might reasonably be expected to be exposed.

So just to talk, so here are the numbers. The ARAL is based on a hazard quotient of one, URAL, hazard quotient of three. And here you see it’s broken down between residential and commercial land uses and a slight variation between 8-hour and 10-hour exposures. So what does that mean? Here’s an example. This is a project where Langan was retained to provide both environmental consulting services and vapor intrusion mitigation system design. And here this was a project where, and I’ll talk about this and one of the case studies in more detail, but this is a project where Retro-Coat was preemptively applied just so that the client could get access to this space and begin their operations. But on the topic of this regulatory change, the URAL and ARAL had to be addressed in the monitoring plans and it specifically requires that employees be notified that they might be subject to temporary relocation if monitoring data indicates that TCE is ever detected at those levels.

Also in the early indoor air monitoring, it was revealed that one of the pieces of equipment actually uses some PCE. So the client was reminded that they need to install and maintain the filters so that the PCEs would remain below detectable levels. And from an employee exposure standpoint, essentially, the monitoring plan for essentially nearly continuous indoor air monitoring for the foreseeable future to be able to protect our employees from the URAL or ARAL exposures.

The second regulatory update I wanted to touch on was one that just came about in January of this year. This was something that everyone had been anticipating for quite some time. But nobody knew about the exact timing of it until it actually was issued. And this was a revision to the environmental screening levels that the San Francisco Bay Regional Water Quality Board basically regulates on. And the driver for this change was that they considered that they wanted to use empirical attenuation factors instead of the ones that had been previously determined using the Johnson and Ettinger vapor intrusion model. And they also had some additional suggestions such as verification of model predictions and also to not forget to evaluate the sewer or utility kind as a potential conduit to indoor air.

And here are some of the numbers. This is just an extremely, extremely abbreviated list. The list goes on for multiple pages, but just to give you an idea of the change from 2016 to 2019. If you kinda compare the numbers, what you see is that the screening levels have dropped by one to as many as three orders of magnitude. And furthermore, additional compounds have been included in the list

And in practice, what strikes some people that perhaps practice outside of the state of California as unusual is that here, the environmental screening levels are in effect action levels and exceedance of one or more of the soil gas ESL essentially means that a vapor intrusion mitigation is required unless a site-specific health risk assessment is prepared. And what that means for our clients is that sites that prior to January of 2019 might have been okay now require mitigation because they’re considered impacted. Furthermore, again, with the change in the screening levels, there are cases where additional CFCs are identified, also from a practical standpoint for people collecting the samples in the field. Greater care needs to be taken to avoid leaks because compound detections then can elevate detection limits, which then renders your data, well, difficult to use or useless. And also, again, because of the lower screening levels TO-15 SIM might need to be used just to get the data that’s needed to verify compliance with these ESLs.

And here’s an example of what that means. This is a rehab of a public housing project in San Francisco. This is like an example where soil gas data previously would have been okay, but as of January 2019, all of a sudden, our client had an impacted site that required vapor intrusion mitigation. So Langan was retained specifically for the vapor intrusion mitigation task. And essentially, what we came down to was we submitted to the regulator a proposal whereby VI mitigation would be done just with an application of, in this case, Retro-Coat. These are existing buildings, where trying to install a ventilation system underneath the slab is very, very cost-prohibitive. And, but our calculations we believe show that membrane-only approach will be fully protective of future occupants. And as a bit of an aside, some pre-mitigation indoor air sampling has already been conducted in a small handful of units and it looks like our existing vapor intrusion risk, even with no mitigation, is very low and possibly non-existent. But more sampling will be done to verify that as this project moves forward. And we are waiting for regulatory approval of our approach.

Here’s another quick example. This is a project in Oakland where again, our client previously had an okay site, but suddenly in January of this year, they now have find out that they need to actually install a vapor intrusion mitigation system. So here, Langan was retained to provide that service, the engineering design of a vapor intrusion mitigation system, which in this case will be a passive venting-and-membrane approach. And the impact on our clients is, you know, they did not have in their project budgets, you know, this type of a system. So they’re looking at an incremental cost that’s not insignificant for engineering design, for regulatory oversight, site visits, etc., and of course the actual construction of the venting and membrane system.

And the third item I’ll touch on is even more recent development. This came out in just July of this year, which is the water board’s fact sheet regarding development on properties with a potential vapor intrusion threat. And I won’t go through each of the key takeaways there. They all make good sense. You know, vapor mitigation is not a substitute for remediation. We see that across in, you know, multiple agencies that the vapor intrusion happens either in parallel with or after remediation has been implemented. There is a greater preference for sub-slab depressurization systems for specifically slab on grade design. And I’ll talk about that more in the next few slides.

Another item is that the water board really wants to have oversight over these projects for the duration of the cleanup and that has some real, you know, cost implications where in the past perhaps folks thought, well, in maybe three to five years, we can demonstrate through sampling that everything is fine. And we can sunset the monitoring program, but that is really no longer the case. People need to think about that if the cleanup is gonna take 30 years, then monitoring is gonna need to occur in some way, at least for the next 30 years, which then leads to the financial insurance requirements. And the water board has seen an, you know, increase in their workload. There’s so much development occurring in the San Francisco Bay Area that they’re now saying that they need a full two months to review documents. But I wanna go back onto this slab on grade caveat here.

So those that have practiced here know that essentially some slab depressurization systems are technically impracticable where you have these types of site conditions. For example, if you’re developing on top of a landfill or an old fill site that has a layer of refuse or compressible soils. Here in the San Francisco Bay Area, we have clay layers that are known as Bay mud or old Bay mud that are highly, highly compressible. We have liquefiable soils. We also have uncompacted fill. For example, the 1906 earthquake in San Francisco was quite devastating. And after that, a lot of the rubble, the debris was just simply brought to the edge of the Bay and dumped into the Bay. And then, of course, there are also areas that have very shallow groundwater tables, you know, as little as 2 to 5 feet below the ground surface.

So if you have any of these types of conditions and SSDS is just not going to work, certainly not the long-term. The photo on the right is a project we’re currently working on. It’s a commercial development on top of a closed landfill. And the next couple slides kind of show you what happens at some point down the road. This is a slide, I know this might be difficult to sort of focus in on, but the upper arrow points to a sub-slab spray-applied membrane that’s doing a fairly good job of adhering to the underside of that structural slab. And in the 10 years or so since this project was built on earthquake fill, you can see there’s about 3, 4 or more inches the settlement that’s occurred. But what’s occurred there is due to the settlement, there were some shortcomings in the construction of the utilities and a contractor was brought in to essentially tunnel underneath this building and effect the utility repairs. So that gave us an opportunity to also go underneath this building and take a look at how our venting system has stood up over time and has dealt with the settlement issues.

And a more extreme example is this one. This was not a Langan design. This was a much older design some 30 years ago on a former landfill. And here we’re looking at 4 feet or more of settlement since original construction. And here, Langan was brought in really to provide geo-technical services because the piles were losing their capacity because they were no longer surrounded by soil but by air. So eventually, these void spaces were filled in with lightweight fill. But again, it gave us an opportunity to go in and look at how this particular system was performing. And we made some retrofits to that system as well. But yeah, in these conditions sub-slab depressurization is just not feasible. So that’s why in the Bay Area, certainly, where we have a lot of pile support instructors, we’ll continue to essentially not really look at SSDS very frequently.

So next I wanted to go into a couple of case studies that look at vapor intrusion and that nexus between regulation, and mitigation, and monitoring. So here’s an example where we have a warehouse that was built on a former naval base back in the ’40s. And the warehouse itself and other areas were identified as sources of contamination and the groundwater. And we had a client who came to us who wanted to lease one of these buildings, this warehouse known as Building 360, for the purpose of converting it to a manufacturing space.

And this is what the warehouse looked like at the very beginning. So you can see on the left-hand side, it’s fairly nondescript, but on the left-hand side, there’s a bicycle leaning against the wall and you see a little square, a little rectangle in the wall. The picture to the right is a close-up of that type of vent. There is a crawl space underneath this building and there are these vents around it at sort of regular intervals around the building, which becomes important as you start to look at the vapor intrusion data.

But stepping inside for a moment at the beginning the warehouse had been more or less cleaned out, but there was some additional cleanup that needed to occur before our client could really occupy the space and also the pictures to the right show what that crawl space look like. There too, the warehouse was built on tiles and because it’s sitting on Bay muds and other compressible soils, and so there’s been some additional settlement that’s occurred. As you can see, the piles are kind of hanging in the air there. You also notice there’s ponded water there. The groundwater here is extremely shallow, as little as two feet below the ground surface. So there’s ponded water, not just below the slab, but also in these utilidors. Those had to be pumped out in order to get access to them. So you can imagine the challenges with trying to sample this space and you can appreciate the technical and practicality of trying to convert this into a depressurization system as well.

So fast forward a little bit. The approach that we took here was we felt confident that the future occupants of the building would be fully protected with a membrane-only system. Here again, we suggested that Retro-Coat be used and also the client identified a moveable wall product, kind of a curtain wall manufactured by Shaver Industries that can be, you know, basically moved down the warehouse as the client expands their operations. But our client was really wanting to get into the space very quickly. So what they chose to do was essentially preemptively mitigate against vapor intrusion so that they could occupy the building and begin manufacturing operations. Ultimately, we’ve collected by now multiple rounds of data which seems to indicate that there’s little or no vapor intrusion risk.

And just to focus in on a couple of things. If you look at the 11DCA results, the screening levels are presented at the bottom and the blue boxes. So for indoor air, the ESL is 7.7 micrograms per cubic meter. For soil gas, it’s 260. And you can see in the bold and the subgrade, we did have some exceedances of the 260 screening level. So we were in the four hundreds and the five hundreds. But in co-located the samples in the crawlspace, you can see that the DCA drops to hundredths of a microgram per cubic meter. So we’re multiple orders of magnitude below the indoor air screening criteria already there in the crawlspace. And then as you go up into either the unoccupied or the occupied portion of the building, you get to a pretty much non-detectable levels of 11DCA and you see a similar type of attenuation for the other two COCs that are listed. Those are just the ones that were actually detected. Other COCs were not even detected.

So now going to a second case study, this is a project we’ve been working on for some time. It’s located in Palo Alto, California. And the environmental consultant performed a soil gas investigation looking specifically for chlorinated solvents because the site sits on a regional plume that dates back to manufacturing activities going all the way back to the 1950s in which chlorinated solvents were used. And sure enough in the soil gas investigation, they found PCE and TCE up into the five and six figures. So Langan was retained to design a vapor intrusion mitigation system for this new development.

And the approach that we took was they’re fairly standard spray-applied sub-slab membrane with a passive venting system. And over the last three-plus years, we’ve collected upwards of 400 samples, plus a handful of sorbent samples. And from very early on, we were fairly confident that we actually had an indoor source of PCE. We did though take a look at the sanitary sewer as a contributor, potential contributor to what we are seeing in indoor air and through a fairly diligent round of sampling of pretty much everything we could collect a sample from. We ultimately ruled out this as a contributor.

And before and after what we’ve been doing is our client has been installing a Retro-Coat in selected areas of the building in the basement. So starting with back in July of 2017, Retro-Coat was applied at the basement level of all four stairwells, and then later more recently in two of the elevator pits, and most recently in one of the trash rooms. And just to give you an idea of what that all looks like, here’s kind of the plan sheet of our piping system layout and just wanted to point out that the piping system leads to four different risers. Loosely speaking, we’ve got four quadrants there. In each of the four corners of the building, you have a stairwell, an elevator, and a trash room. And the stairwell and the elevator are kind of, you know, frequently thought as a potential, you know, preferential pathways for vapor intrusion.

What caught us by surprise here, which is the real lesson learned is the importance of the trash room. But before we get to that, just a little more background, we were monitoring PCE and TCE concentrations in the risers, which are we believe generally indicative of what’s happening immediately beneath the slab. And we can see it took about a year for conditions to sort of stabilize. But since about April of 2017, PCE and TCE concentrations in the sub-slab have been very, very similar, certainly similar in terms of orders of magnitude.

So as we were looking at the indoor air results for one of the stairwells, in this case, stairwell two, that’s where we saw the greatest PCE detections in terms of magnitude and frequency. But you look over at the TCE graph on the right and those concentrations look quite different. They’re much, much, much lower, generally below 0.2 micrograms per cubic meter. The dashed black line is the residential ESL which doesn’t exactly apply in the stairwells, but it’s a good marker to use for reference. And also, just to point out on the left hand Y-axis are the indoor air concentrations for PCE and TCE respectively. And on the right-hand side, you have the riser concentrations which go up into the thousands.

So you can see the riser or sub-slab concentrations have varied quite a bit over time, at times down into the double digits, but at times up into the quadruple digits. And yet you don’t see that type of response in indoor air. So to us, you know, this looks a lot like there’s not exactly a connection between what we see in indoor air and what we see under the slab. Not only did the PCE and TCE concentrations not track what’s happening under the lab, they also don’t track each other.

And lastly, this yellow line is the marks, the date where Retro-Coat was applied at the basement level in all four stairwells. And I think it’s fairly obvious that that application of Retro-Coat hasn’t really affected the data. And to us, that means that we are not looking at a vapor intrusion condition. There’s something else going on and we’re quite sure that it’s an indoor source. And similar type of data for the hallways. So the hallways are up on the second and third floors. Again, there’s a disconnect between what you see under the slab and what you see in indoor air in terms of TCE versus PCE concentrations. And again here, the concentrations in the hallways have not been affected by either the application of Retro-Coat in the stairwells back in 2017. More recently Retro-Coat’s been applied in the elevator pits and you might think, “Oh, that’s, you know, that’s helped bring down the concentrations.” But we had the presence of mind a couple of years ago to actually start looking at what’s happening in the trash rooms. And if you look at the architectural drawing in the corners, you can see there’s a trash room and there’s a very small dash circle that actually is a trash shoot and residents that live on the second and third floors can go to the corners of the building and basically drop their trash down the trash shoot, which ends up in a dumpster down in the garage level.

And if you look at the PCE concentrations in the hallways versus the PCE concentrations in that trash room, I think it’s fairly clear that the hallways respond to what’s going on in that trash room. And when we detected these first initial results, we had a conversation with the building ownership and building management and they took further measures to restrict tenant access to the actual trash rooms. What it looked like was that tenants, it was kind of an open secret among tenants that those doors could just be pushed in even though they were locked and tenants were dumping all kinds of stuff into those dumpsters. And it would appear that one of those tenants is doing something. We don’t know who it is, we don’t know what they’re doing, but they are using PCE or some type of a product that contains PCE.

So we’re continuing to chase this down, but it seems like hardening the trash room doors has caused this tenant to, if not quite cease and desist to at least reduce their activities and reduce their dumping. So here, kind of coming back to Retro-Coat, I think that the application of Retro-Coat has been helpful in that it hasn’t affected what we see in indoor air, but it has definitely helped us to really make the case that what we’re looking at is not a vapor intrusion problem but an indoor source.

So just to touch very briefly on sewers and utility tunnels, I had mentioned earlier that for this particular project, and this one photo was taken out in the street in front of that building. We did do a fairly extensive investigation of the sewers as a potential contributor to what we were seeing in indoor air, and we did ultimately rule that out. But for those that are needing to undertake this type of an investigation, I just wanted to point out that for those that are not familiar, there’s a DOD-funded program, sort of an ESTCP and one of their teams has developed a conceptual model and an investigation protocol for these types of investigations. We would’ve been happy if we had had this available to us when we tried to do this. But for those that are needing it, this is available now.

And lastly, I wanted to mention in another research effort, this one under ITRC, the Interstate Technology and Research Council, which essentially supports state environmental regulators. There were a couple of vapor intrusion guidance documents that came out in the past. 2007 was the VI guidance, which was followed in 2014 by the Petroleum Vapor Intrusion Guidance. And then both of those guidance documents had their training programs associated with them. This is very typical for how ITRC works. Guidance documents are then followed with training programs. And currently, there’s a team which I’m a member of who’s tasked with creating a new vapor intrusion training program and any supplemental documents that we might feel are helpful. And the goal of this revamp is to assist end users generally thought of as regulators, but certainly the consulting community as well with determining appropriate vapor intrusion controls for specific sites or situations, identifying performance closure, consideration strategies and ultimately to assist them in evaluating vapor intrusion submittals.

And for the moment, the team is focused on three broad areas and the one that kind of sets the stage is the site conceptual model or conceptual site model. People use different phrases, but what we wanted to do is narrow that down to vapor intrusion and really identify those factors that need to be understood in order to develop an effective vapor intrusion mitigation strategy. And what we’ve already kind of identified is that because regulatory requirements vary so much from state to state, from jurisdiction to jurisdiction, is that even with the same site conceptual model in four different States, you might have four different consultants who come up with four different vapor intrusion mitigation designs. And that’s just because there are regional differences in guidance and regulation. And then the team is also gonna look at, you know, passive venting systems, different membrane products and also active venting systems, including sub-slab depressurization systems. So you can look for that to come out hopefully in October of next year. That’s our target deadline.

So just to wrap up in terms of trends, I think what you see is an increasing recognition among both regulators, consultants and certainly, our clients that vapor intrusion continues to be a very complex field with a lot of confounding factors and a lot of intricacies. I’ve just named a few preferential pathways. Just think back to the trash shoot as a, you know, who would’ve thought that a trash shoot was a preferential pathway, but it certainly can be. Then the special challenges posted by rehabbing/retrofitting existing structures. For example, the warehouse case study that I touched on. And then the myriad of potential indoor sources, be it benzene emitted by forklifts during construction, you know, PCE from manufacturing equipment even today. And then, you know, random residence in a residential, you know, multi-units structure, you know, who knows what people might do.

And then for a typical of urban areas, we have confounding factors, just general air pollution. You know, benzene has long been known to be one of those contaminants that’s ubiquitous. There are others certainly and then already touched on sewers and utilities. And so what that all boils down to at least where we are here in the Bay Area, but I think this is true kind of throughout is that regulators are asking for a greater density of samples, more and more sampling locations, you know, not just one elevator pit, but all the elevator pits, you know, that type of thing. Greater frequency instead of maybe annual, we’re now looking at semi-annual or quarterly and longer monitoring periods. If that groundwater plume is going to be around and gonna be, you know, remediated over the course of the next 30 years, then you need to be prepared for some type of monitoring program for potentially as long as that same 30 years that the plume is being remediated. So what that means is as our understanding of these types of sites and the regulations continues to evolve for our clients. You know, owners, developers, public agencies, there continues to be some uncertainty as to, you know, what they’re looking at down the road. But that’s where we are. With that, I’m done for now and I’ll turn it back to our host.

Rick: So, great. Thanks, Sigrida. This is Rick Gillespie. Just do a quick transfer of the screen over to me. I just wanna say thank you. Did a very thorough job of evaluating different technologies. So to be employed to address vapor intrusion mitigation at new and existing buildings. Just as a reminder to the group, you do have the ability to post questions. We will have a Q&A opportunity available for Sigrida at the end of the presentation. So just use the GoToWebinar question box to post your questions there.

So Dane, I’m gonna ask you guys just a quick question. I’m having some audio issues on my end, so I just wanna confirm that you can hear me.

Dane: Yeah, we can hear you great.

Rick: Perfect. Okay, I’ll just fight through it and we’ll keep going. So I’m gonna build on Sigrida’s presentation and just spend a few minutes discussing some exciting developments at Land Science. For those of you that I’ve not had the pleasure to meet with, my role at REGENESIS and Land Science is to support our team across North America. In my 20 years of REGENESIS, I’ve been fortunate to be a part of an incredible track record of technology innovation for both soil and groundwater remediation as well as vapor intrusion. So there may be a few people on the call that they didn’t realize or didn’t know that Land Science was actually at a division of REGENESIS from the very beginning. That’s important because REGENESIS has a 25-year track record of product innovation, of bringing new technologies to the environmental market.

So Land Science is recognized as an industry leader and at the forefront of AI mitigation. Between the two companies, we have combined experience at more than 26,000 contaminated sites worldwide and over 27 countries. That visibility gives us a very unique perspective. In working collaboratively with engineering firms, federal and state regulators, end users and applicators, we’re just in a very unique position compared to other vapor intrusion providers. Our research and development team led by Kristen Thoreson from REGENESIS and Hieu went from Land Science creates a truly unique situation where solutions are developed for complex VII conditions and then supported by the highest levels of scientific research.

In addition to our R&D team, our Land Science team is positioned across the US to provide local support including design assistance, assistance in developing specifications, assisting engineering firms with every aspect of the project. We also help regulators to evaluate various options and to work with our team of certified applicators to ensure that every application is a high-quality installation. Land Science entire focus is to build and implement the best or the absolute best vapor barrier solutions in the marketplace today.

So Land Science offers a full suite of vapor intrusion technologies. Our core technologies include TerraShield, Nitra-Seal, MonoShield and Geo-Seal. These are all composite membranes for new construction. In addition, as Sigrida mentioned, we manufacture Retro-Coat for existing buildings. Each one of these products are designed to fill a specific niche required by the environmental industry.

The other thing we pride ourselves is in quality assurance and quality control. Only contractors that we certify are allowed to install Land Science vapor barriers. We provide them with continuing education and oversight to ensure the quality of the installation. In addition, and probably more importantly as we train and certify third-party inspectors to warranty that barrier to ensure that it’s installed properly. And for those of you that are on the call, if you’re an environmental consultant, I encourage you to get more information on becoming a third-party inspector. This incorporates you into the QA/QC process and helps for you to be part of that chain of command to ensure a successful installation.

So just a quick note here. So when we talk about contaminant vapor barriers, they’re often evaluated by two primary criteria. Chemical resistance is the ability to block vapors and then constructability which measure ease of installation and more importantly, the quality of the installation. It is the combination of these two factors that often determine which barrier is selected. There is a third criteria and not shown, but it’s always valued and always considered on a barrier selection that’s cost. So it goes without saying that all the barriers that we will discuss today are comprised competitively within the marketplace. Our focus is gonna be on chemical resistance and constructability. So, and I’ll get to that slide just a moment. We did have a technical issue, so I’m gonna go back one for Dane.

So I mentioned earlier that technology innovation is at the core of who we are as a company. The following is just a general timeline for the development of passive mitigation barriers. Beginning in the early 2000s, the marketplace saw the entry of spray-applied asphalt emulsions. These systems evolve from the waterproofing industry and methane mitigation barriers, which were widely applied in certain markets like the methane zone in Southern California. These early rubberized spray-applied asphalt systems provided relatively high constructability, but low chemical resistance. Against primary contaminants that most of us are dealing with environmental sites. Petroleum hydrocarbons like benzene, chlorinated solvents like TCE are often absorbed into these latex barriers and chemical resistance testing just generally wasn’t available.

Since REGENESIS was not from the waterproofing industry, we recognized immediately that these modified asphalt barriers would likely not meet regulatory standards. In 2007 Land Science for the industry Geo-Seal, the first composite vapor barrier. This was adapted from the waterproofing industry by our scientists with an advancement over simple spray-applied products being promoted as contaminant vapor barriers at the time.

Over the past decade, Land Science has committed significant resources to developing new materials and new technologies to increase the cost effectiveness and more importantly, the chemical resistance of our barrier system. Since 2015, we’ve led an internal R&D process to develop new approaches. Simply put, we weren’t satisfied with the success of our original Geo-Seal system and knew it was time to improve. Folks within our team like Hieu Nguyen and Kristen Thoreson, our full R&D team were instrumental on developing a new nitrile core material. This represents a major improvement over SBR type asphalt latex emulsions by protecting against Permian’s, against other organic contaminants.

So we talked a little bit about chemical resistance a moment ago. I’m gonna get to constructability as well. Constructability, you can have the most chemically-resistant barrier out there, but if it’s too rigid, difficult to install, if it uses tapes at the scenes or the penetrations or the perimeter terminations, or if it doesn’t use certified installers, you’re very likely to have challenges installing that quality vapor barrier. Land Science prides itself on our systems representing the highest and chemical resistance with a high degree of chemical resistance.

We’re proud to announce that we have three new vapor barrier technologies on the market. Today, we’re gonna focus on TerraShield, but I do wanna introduce these quickly. TerraShield is the most chemically resistant vapor barrier on the market today. This new barrier incorporates layers of combined with an innovative nitrile spray-applied core. It offers maximum protection and for construction projects while maintaining excellent constructability. Nitra-Seal provides all the constructability of our original Geo-Seal system which is updated with nitrile spray-applied core offering 10 times greater protection against vapor intrusion against traditional spray-applied systems. And then finally MonoShield. MonoShield’s specifically designed for preemptive mitigation sites that have historically used thin mill plastic sheets with tape seams or rigid HDPE with heat-welded scenes. MonoShield is a rapidly applied single ply nitrile system. It’s an excellent solution for those preemptive sites, say large warehouses where people have traditionally used 10 mil plastic seats or heat welded HDPE systems.

So the figure here is a TerraShield and we’re gonna get to some chemical resistance testing in a moment, but I just wanna kind of go through the basic components of the TerraShield system and the innovation that is within that. TerraShield incorporates innovative dual metalized film technology that provides superior chemical resistance. This metalized film layer provides 100 times greater protection against contaminant vapors compared to 10 mil HDPE that has been used traditionally and not spray-applied barriers. The TerraShield system also is comprised of an innovative and highly chemically-resistant Nitrile spray. That Nitrile core provides 10 times greater chemical resistance to VOCs than traditional SBR Asphalt Latex.

In addition to the greater chemical resistance, the Nitrile trial also provides improved tensile strength and puncture resistance along with a reduction of tackiness at high temperatures. It’s understated for, as they were really excited about this new VI barrier and some of the features and benefits that come along with it. So TerraShield is specifically designed for brownfield redevelopment sites where VOCs are present. I do wanna get into some of the chemical resistance testing that we talk about. Here at Land Science, we talk about chemical resistance a lot because it’s so critical to developing true vapor intrusion solutions.

Chemical resistance really matters when we are protecting human health. From the development of TerraShield, extensive studies have been performed to understand the relative chemical resistance of TerraShield compared to other systems in the marketplace. So what we’re gonna go through is just the testing that’s been done. First, we compare to our Terra base, which is our dual metalized film at the base of the composite system against 10 mil HDPE. The purpose of this task was to evaluate the relative chemical resistance between our new Terra base and older HDPE base layers. The second portion of that test was to compare our new Nitrile core to older typical styrene-butadiene modified asphalt core.

A simple way to think about this is the innovation between Nitrile gloves and latex gloves. Our Nitrile core provides greater chemical resistance to contaminants and greater puncture resistance. So the figure on the right shows our custom made testing apparatus consisting of a top and bottom chamber separated by the material to be tested. Results will show the relative performance of our Terra base versus 10-mile HDPE and then second are Nitrile core versus SBR test, SBR. Both were tested under identical conditions.

So the figure on the left shows the results for Terra base versus 10 mil HDPE. These results were obtained by comparing the relative TCE flux through two barrier materials as measured in the top chamber. The results of the study indicate that over 100 times less TCE diffuse through Terra base or said differently terra bases 100 times more protective than a 10 mil HDPE. The figure on the right shows the results of Nitrile core versus typical SBR Modified Asphalt. The Nitrile Modified Asphalt shows an attenuated rate of TCE diffusion that has over 10 fold lower than TC flux compared to typical SPR modified asphalt.

The real purpose of this testing was to show that the improvements to barrier materials could result in significant improvements in chemical resistance that could be quantified in terms of TCE, mass flux with 100 times greater chemical resistance of Terra base combined. With 10 times can rate or chemical resistance of our new Nitrile based core, we believe it represents a significant improvement over any vapor intrusion barrier available in the market today.

Just wanted to show a quick slide on low-profile venting. Typically done, these are the passive or active venting systems that are often recommended for all of our barriers. These low-cost systems provide maximum flexibility and an additional layer of protection for any passive mitigation system. So as I mentioned at the beginning, our Land Science team, the entire focus is to support your project from beginning to the end. Our team is available to review analytical data to make recommendations based on site conditions, to help with venting layout and venting design, to help with construction specifications for the GC process and any drawings that might be required to get you all the way to the installation.

And then finally, we’ll have just a couple more slides and we’ll get to your Q &A. I want to talk a little bit about vapor barrier systems with warranty. We offer industry-leading warranty options for very pro barriers including material and system warranties from 1 to 30 years. These extended warranties do require site-specific evaluation, Land Science. In addition, for extended warranties, we have third party inspection to ensure the quality of the installation. But warranties really help you to ensure that your investment is protected for the long term.

So very quick overview of some of our new technologies including TerraShield and Nitra-Seal and MonoShield. We have a number of questions that have come in to the group. So I’m gonna go ahead and ask a few of Sigrida. Feel free to ask your questions and we will get to them as many of those as we can. So give me just a moment, Sigrida, I’m pulling these up to ask you a good one. All right, I’ve got the first question here. This comes in from Bill Schwake. So this is for, Sigrida. If a dry cleaner site was closed via no further action in 2017 and had HHRA completed including J&E modeling, is that closure still valid?

Dr. Reinis: That is a good question. I would say it depends on the jurisdiction. If you were in the San Francisco Bay Area, that might no longer be the case. Again, because those screening levels came down. Now with the site-specific HHRA, there’re two. Hopefully, you’re still good, but I couldn’t guarantee it. You might need to… You know, what I’ve done is I’ve gone back to the actual regulators and just said, “Hey, look, you know, we’ve just been retained by such and such client for this and such a site. It was previously closed under your program. You know, what’s your involvement now? Do we need to work with you or, you know? So to me, you know, erring on the side of caution is the best to do is reach back out to the regulator and ask them. That would be my recommendation.

Rick: Good. I’ve got a technical question based on the sampling that you did at the warehouse location, this comes in from Lisa Augusta, says, in the warehouse, how were the samples collected from the crawlspace?

Dr. Reinis: Very carefully. You saw the photo there with the stairs that went down into the Utilidor where we had access hatches such as those, we use those. It’s my understanding that the field crew did pump the water out from areas where they were gonna need to get access. But ultimately, they were Summa canisters that were very carefully-attached to and suspended from those ladders. And in other areas where the surface of the crawlspace was firm and seem certainly safe enough, there we actually, in some cases, installed temporary soil gas probes and collected soil gas samples there and then the actual Summa canister within the crawlspace right there where that soil gas probe was. And then after closing everything up for the duration of sampling collected in indoor sample above the slab in that location as well. So what you saw in that little cross-section cartoon were these, you know, triple co-located samples. But yeah, Summa canisters and just very carefully suspended on those ladders.

Rick: Okay, great. Here’s one, I’m gonna combine two questions related to the Retro-Coat application and I’ll take. One is just a general question on cost per square foot. And I’m gonna add another question here about kind of preparation does the slab need. The reason I’m combining those two is because slab preparation, really, is one of the primary drivers for Retro-Coat costing. So let me ask at high level or answer at high level for, so generally Retro-Coat applications range from about $5 to $9 a square foot installed. They can go higher under unique conditions. And those unique conditions can be varied, but often they’re related to the quality of the concrete. So if you’re dealing with a structure or a building that either has very old concrete or concrete that’s been damaged over time through operations of the building, it’s gonna need more prep, more grinding, more repairs, all those types of things would drive costs.

Square-footage also comes into it. Oftentimes, people will come to us with, you know, maybe it’s 1,000-square foot facility or even smaller. Those tend to be higher just based on the size of them and moving to them. There’s some economies of scale as the square foot’s increase, but five to nine is a good general rule of thumb. Always encourage folks to reach out to our team and they can give you a lot of more detailed saying, “Okay, this is… We can help you with an onsite inspection. We can get certified installers to come out and take a look at it for you.”

That’s great. You’re getting some good ones. I’m gonna come back to you. So this one says, please discuss the need for post-installation, indoor air confirmation sampling, especially for new construction. In regulatory guidance this is often not clear, but suggestive sampling should be done. This is from the question, but rarely sees those samplings being collected and practiced. Have any guidance or thoughts on that topic?

Dr. Reinis: Well, it seems to be in part that’s a reflection of different regulatory environments. Certainly here in the Bay Area, whether our site falls under that, well, we have, for those that are not familiar, we have two state agencies. There’s our water quality control board and the department of toxic substances control. And your site may fall under the regulatory purview of one or the other agency. And further, with the water board there are, you know, nine different regions and we are in the San Francisco Bay region. And the San Francisco Bay region takes kind of its own approach to regulating these sites. But what I can say is that either agency, you know, they’re quite and not just those agencies but also at the county level, whether you’re talking about San Francisco County or Alameda County. Those regulators are very assertive in terms of wanting to see the mitigation system design. They want to see a monitoring plan. They want to see an operations and maintenance plan. And they will review and comment on those documents.

And that’s where on that last slide I was saying, you know, we’re seeing, you know, more sample density being requested, more greater sampling frequency and potentially a much longer duration of sampling. So, you know, here I would say that that indoor air sampling post-construction does get done and the regulators keep a very watchful eye on that program. So, you know, there may be other areas, other jurisdictions where, or that’s not quite the case which I can’t speak to, but certainly here the monitoring does occur.

Rick: So we’ve got a ton of great questions. If we don’t get to yours, I promise we will respond to each and every one of them. Dane, feel free to interrupt. But I’m gonna keep answering, keep asking them until you tell me to stop.

Dane: So I think yeah, sorry. We’re past time right now, so I think we should probably wrap up the Q&A portion at this time. But yeah, as you said, Rick, if we didn’t get your question, someone’s going to make an effort to follow up with you. So that’s gonna do it for today’s presentation. If you’d like more information about environmental services from Langan, please visit langan.com and if you would like to learn more about vapor intrusion solutions from Land Science, please do visit landsciencetech.com. Thanks again so much to our presenters today, to Dr. Sigrida Reinis, and to Rick Gillespie. And thank you to everyone who could join us. Have a great day.

Rick: Great, thank you.