The Vapor Intrusion Risk Pathway: Regulatory Updates & Continuous Monitoring
Video Transcription
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 with the webinar today, I have just a couple of 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 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 do not address your question, 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’ll be sending out a brief survey following the webinar to get your feedback.
Today’s webinar will focus on updates regarding the vapor intrusion pathway including regulatory updates and continuous monitoring. With that, I’d like to introduce our presenters for today. We’re pleased to have with us today Dr. Blayne Hartman, of Hartman Environmental Geoscience. Dr. Hartman is a nationally recognized expert on soil vapor sampling, soil vapor analysis, and vapor intrusion. He’s provided training on soil gas methods and vapor intrusion to state regulatory agencies in over 30 states. His organization, Hartman Environmental Geoscience, provides vapor intrusion, soil gas and analytical expertise, and specializes in VI and soil gas training, real-time continuous monitoring of TCE and other VOCs in indoor air, and vapor intrusion regulatory guidance.
We also have with us today Dr. Mark Kram, founder and chief technology officer for Groundswell Technologies, a group specializing in automated cloud-based monitoring and modeling of environmental sensor and analytical instrumentation networks. Dr. Kram has over 30 years of experience using innovative environmental assessment techniques and has authored articles, national standards, and book chapters on the subject, and taught graduate level courses on related topics.
We’re also pleased to have with us today Tom Szocinski, director of Vapor Intrusion at Land Science. Mr. Szocinski is a nationally recognized vapor intrusion expert with over 18 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 development of vapor intrusion and mitigation guidance, regulations, and exposure criteria.
All right, that concludes our introduction. So now, I will hand things over to Blayne Hartman to get a start.
Dr. Hartman: Okay. Thanks and hi to all of you out there. I took a quick look at the attendance list, see a lot of familiar names. So thanks to all of you for signing up and listening. As usual, Mark and I have about two hours of material which we’re going to squash down in about 40 minutes of time. So the first thing though I want to say is, don’t forget this everybody, this is our Valentine’s Day special seminar, and if you don’t take anything else away from this webinar today, remember, in two days, remember your sweeties.
All right, here we go, these are the topics we’re going to cover. Current hot topics going on in the vapor intrusion world, that’s what I will cover. And then Mark will…Dr. Kram will get up and talk about the high resolution continuous monitoring, the lessons we’re finding out by using that technology.
Why is vapor infusion such a concern? Long distances, meaning that we have very wide nets, both spatially and vertically. Lots of compounds, EPA lists about 80 possible compounds, although in reality, we generally worry about 10 or less. Low screening levels, we’re measuring parts per trillion for some of these compounds. Lots of receptors, people, of course, but we’re also worried about animals in some cases, bird eggs, turtle eggs. We’ve even been worried about fruit, in some cases. So when you put all that together, it keeps the vapor intrusion pathway still a very, very hot topic, although it’s now fallen to number two, probably behind [inaudible 00:04:23].
All right, hot topics, what are they? These are the topics that are still being debated at the vapor intrusion conferences: sewers, indicators of vapor intrusion, use of models, attenuation factors, and is still the short term trichloroethylene exposure issue. So we’ll go through these very quickly.
Sewers, you can think of sewers really as just another indoor source. And as long as you keep these P-traps wet, you’re gonna block that potential…a pathway in from a sewer. So when do we tend to see impacts from sewers? We tend to see it in structures, it can be a house, it can be a commercial building, where they have a sink or a shower that they have not used in a long time, they go dry, and then the sewer get vapors are able to enter the structure. So as long as we keep these wet, then really, the only other pathway into the house from a sewer might be from the leaky wax ring around a toilet. And if that’s leaking, chances are you’re gonna smell it when you’re on the toilet.
All right, sewers are easy to sample, if you suspect they’re a source. It’s very easy. You can run up on the roof. You can sample the roof vents. You can go to clean-outs that are usually right next to the structure, outside the structure. You can even go to the P-trap, drill a very small hole on the sewer side of the P-trap, a very tiny hole, stick a syringe needle through, collect a sample, and analyze it. So sewers are very, very easy to assess if they are a potential inside source.
Vapor intrusion indicators, the idea, the concept is can we use some easy to measure variable to predict when vapor intrusion is essentially turned on or occurring? So what are some of those variables? Well, how about wind speed, for example, barometric pressure, temperature change, radon concentrations? Well, EPA, at least the EPA headquarters out of Washington, D.C., they’re really, really interested and focused on this issue. They’ve held all all-day workshops on this topic at AEHS in March 2017, March 2018, AEHS in October 2019, and they’re doing it again this March, in 2020. So this is a topic of high focus for them. But the question I always ask is why would I want to do this? Why do I want to only sample when vapor intrusion is essentially turned on or its maximum? When we’re talking about risk to occupants, we’re supposed to do this under nominal conditions, not when the results will be biased high or biased low. So that’s what I consider to be one disadvantage of trying to find an indicator for VI.
All right, modeling getting the boot. Most state agencies now are shying away from modeling, in some cases, not allowing it at all. Instead, they’re asking you to go to the Vapor Intrusion Screening Level calculator, VISL, the Visual Vapor Intrusion Screening Level calculator, and use that instead of using a model. Now, there’s a lot of people I saw on the signup list from California, and notice, in California, the second bullet, I put a couple of question marks. In May of 2019, California’s HERO, DTSC HERO came out and said they do not recommend use of the models. Last week, at CalCUPA, I happen to listen to a DTSC staff person say modeling is going to be allowed again, but only for a limited purpose. So we’re still waiting to see exactly what that limited purpose is. We know that’s not going to be allowed as a exit ramp only. On the other hand, will it be allowed to determine attenuation factor? So we’re still waiting to hear what the California agencies are going to come out with. And the water boards, are they gonna follow DTSC’s lead or not? California’s still very much up in the air for all of you listening from California.
So if we’re not using models, what are we doing? Well, let me say this first, the EPA decided to really confuse us by taking down the old Johnson-Ettinger Excel spreadsheets and basically say we don’t support or we’re not…favors of doing modeling. However, then in September 2017, lo and behold, they put new versions of the J-E model up on their website, and it’s still there, by the way. However, the text says it’s not intended to replace the VISL. It says, for screening, go to the VISL spreadsheet tool. So that makes you wonder, well, then, what’s the point of the model? We also have found bugs in the model. For example, the third bullet, the ventilation rate changes the risk for soil gas data, but not sub-slab data. In other words, if you double the ventilation rate of a room, the indoor air concentrations don’t change for sub-slab data, but they do change for soil gas data. It makes no sense. There’s other bugs too that I won’t go into, but the EPA has actually sent an email to some people saying that the model should not be used because of all the bugs in it. So that’s the status on that. And all it’s doing is making things more confusing.
All right, so that leads us to the attenuation factor concept. Now, this is the plot in the EPA’s own 2012 document, that’s the title of the document there, I listed it straight from the document, except that I put in red “residential” and underlined it to make the point. It’s a plot of indoor air versus sub-slab concentration. So in other words, every one of those points you see is where they had indoor air and sub-slab data in that structure, not necessarily at the same time. So what you should see there is it’s a lot of scatter in that plot. It’s a very poor correlation if anyone try to do a regression analysis on this plot that would get a very low regression, r-squared, and probably not be acceptable to most oversight people. So keep that mind, a lot of scatter in the data.
All right, where’s the database come from? Well, this is a map showing where those sample points come from, and you can see it’s heavily skewed by three areas, the Northeast, mostly New York sites, Colorado sites, and San Francisco Bay sites. And except for that, you can see there’s very poor coverage for the rest of the country. So that should raise some red flags to you of if you’re in any one of these other states, no, really, are these data applicable to us or not?
All right, so that raises the question that, all right, if we’re going to use this default attenuation factor of 0.03, then why are we using it when the conclusions from this study do not say it should be used at all times. So in this box is the actual table in the conclusion section of this document, the EPA’s own document. And what you see is that the 0.03 applies to residences with basements or all residences of all types of foundations. But if you look at slab-on-grade residences only, if that’s what you look at, the attenuation factor is 0.01. So why are we using 0.03 in the VISL calculator for all structures, and what about commercial structures? The database is for residential buildings.
Well, let’s look at the data plot, the same plot of indoor air versus soil gas concentration for commercial structures. Th ere it is. No, that’s not a mistake. There are no data. At least the EPA hasn’t compiled such data. So what to do for commercial structures? Use 0.03? That doesn’t have any real jurisdiction or application.
Well, a couple of people have done some things on this. Robbie Ettinger and a group of his colleagues from a couple other companies, they went in mined some data from California, mostly commercial with some residential, and if you look in the center column, you see at the 95th percentile, the EPA’s…there’s the 0.03, 0.26 which is round up to 0.03. If you look to the right of that, from the California database that Ettinger and his colleagues put together, it came out to be 0.002, about a factor of 10 lower, which means a factor 10 higher screening values. So that’s a recent study by Ettinger.
Now, another study going on or compilation, I should say, is being done by Suzie Nawikas of H&P Mobile Geochemistry. H&P has collected a lot of samples over the years, both indoor and sub-slab for radon analysis, so Suzie began mining the radon data. She gave a presentation last week on this in CalCUPA Burlingame, and here’s what she found out. All right, these are for commercial structures. Are you ready? The answer is 0.004, much lower, almost a factor of 10 lower than 0.03. If your interested in different percentiles, there they are. They’re even lower, of course. The 0.004 is the 95th percentile. So what that means is 0.004 is one unit the indoor air for every 250 below. And in contrast, the EPA, is course, 0.03, 1 to 33 units.
All right, so we have two studies now or compilations that have been done. If you simply take the point 0.01 for slab-on-grade structures, which most commercial structures are, and you make an adjustment for the difference in exchange rate, which depending on the state is at least a factor of two, so if you’re ventilating the structure two times faster than a house, then you should be able to take that 0.01, essentially divide it by 2, fast exchange rate, and lo and behold, the attenuation factor you would get for a commercial structure would be 0.005, just a quick little simple arithmetic. Suzie Nawikas’ study said 0.004. Ettinger, which is a combination, 0.002.
So we have essentially three independent lines of evidence saying that 0.03 for commercial structures is way, way too conservative. We should be at least closer to 10 times lower, which means 10 times higher screening values. So we’ll see where this goes with the agencies. I know that California DTSC is going to do their own compilation. I don’t know when that’ll get finished, but my guess is that we’ll find out it’ll fall within the range of these three numbers here, anywhere for 0.002 to 0.005. That’s what…for the regulators that are listening, that’s…would be a much more, should we say, representative of the attenuation factor to use for commercial structures.
The other thing you can do is go measure radon, and use radon as a surrogate. Measure radon indoor air, measure radon under the structure, and then calculate the attenuation factor by simply the ratio of the two. I advise doing that all the time, whenever I do sub-slab sampling.
All right, the final point, the short term trichloroethylene exposure. This has, of course, been still the hottest vapor intrusion topic for many years now. Let’s see what’s going on with it.
Johnson et al, this is where the study came from, you know, this is like 10 years old now, roughly, and what they found was that they had malformations of the heart in my mice fetuses, but it was based on oral exposure, not inhalation. Okay, the mice were drinking water that had been laced with TCE. There’s actually been five studies that have done this, some were before the Johnson study, some were after, and none of the other studies could reproduce the Johnson study. None agreed with the Johnson study.
All right, so the solvent industry said, “Wow, you know, we really need to put this issue to rest. We need to do a more advanced study, a more controlled study, and see if we can reproduce the effects of the Johnson study.” So they did. In 2018, they did the study. They tried to mimic the Johnson study, indeed they did it also based on oral, because they wanted to do exactly what the Johnson study did. Completed in the summer 2018. What did they find? No treatment-related effects. The results of the study have been peer reviewed and published in “Birth Defects Research” journal. The results have been submitted to EPA. As far as I know, we’re still waiting for an EPA response.
There’s the study right there. I included this so that you can go and download it and read it yourself. That’s the peer reviewed journal article. So this would say there is no short term trichloroethylene issue.
All right, so that’s an update on what’s going on with the hot topics. So now, I want to say to you that I’ve been doing vapor intrusion since 2005, I’m sorry, 1995. So what’s that? It’s almost 25 years now. And the fundamental problem with vapor intrusion assessments is we don’t get enough information to be able make decisions, to be able to figure out what’s going on. So when we’re using passive samplers or canisters, this is what we end up with. We end up with a data point. And sometimes that’s the only point you have in a structure. Sometimes, you have more than one room, but sometimes that’s what you get. If that’s the screening level right there, then what you have is an exceedance just above the screening level. What are you going to do? You’re going to go back. What happens when you go back and you get this? Now, what? Probably you’re going to go back, and now, you get this. So now what? And this is what is very, very common in vapor intrusion investigations is without enough data, it’s very, very difficult to figure out what’s going on. And these delays, from the first sample and event to the second or third can go for many months, sometimes even years. I’ve seen projects where they’ve been going out with canisters for two, three, four years, and not figuring out what’s going on.
So the good news is we have technology that can overcome this problem, this fundamental problem, and that’s what Mark is going to talk to you about next.
Dr. Kram: Thank you, Blayne. And thanks everybody for joining us today. I’m going to quickly cover a couple of key points here. Obviously, I want to update you on the findings over the past few years using continuous automated monitoring. And if there’s a take home message, it would be that we’ve been able to recognize some of these key patterns with a single field campaign.
Dane, can I have the next slide, please. So the outline will be as follows. I’ll discuss a couple of the key questions that we’re always trying to answer. I’ll describe the technology briefly, and then I’ve selected samples and examples to make a couple of key points. Some of these are based on something that Blayne just mentioned, for instance, where previous data had been collected but some of these key questions remained. And then, I’ll summarize.
Next Blayne, or Dane, thank you. So the key questions that we often find ourselves asking, is there even an exceedance? And if so, what’s causing it? Is it an indoor source? If so, where is it and what’s causing that? If it’s really vapor intrusion, where is it coming into the structure? And how long are these exposures for? That gets back to some of the things that Blayne was talking about before regarding the indicators, if you will. And then what can we do to reduce that risk and does it work? Next, please. And I submit to you that when you see these dynamic data patterns, the spatial and temporal relationships and correlations, we can get these answers very quickly.
Next. So as Blayne mentioned, a couple of the items and considerations when you’re looking, for instance, at the TCE assessment options, where at least, for now, we want to be able to respond very quickly. With the passive, time integrated options, you get one number over that sampling duration, and so you don’t really get to see that pattern, and often, you can’t answer these questions, particularly in a single mobilization. And since there’s no real-time feedback, the responses are often delayed. And we’ve seen where you can get a false negative or a false positive, and then, getting back to the indicator issues that folks like Henry Schuver’s focusing on, the reasonable maximum exposure questions arise. In fact, they are stating that you need 58 randomly timed samples to meet the criteria that’s articulated in the 2015 EPA guidance. And it becomes costly if you have to go out there often or do multiple rooms.
Next, please. With the continuous automated analyzers, you get to see a pattern and it jumps out at you. You can track chemistry as well as the controlling factors. And that allows you to answer these key questions in short order. And you can even automate those responses. Next, please.
The system that we’ve been deploying is fully quantitative. It’s not a screening method. Next. You can meet the requirements for some of these screening levels for TCE, PCE, vinyl chloride, and other VOCs. Next. The analytical time is very short. So within 10 minutes, you can get a sample and then you can go to the next location. It’s all automated so that you can sample from up to 16 locations. We can actually modify that and update that to 30 locations, and we know the GPS coordinates, so we get spatial along with temporal. It’s essentially a modified EPA method TO-14A. Instead of bringing the canisters to a robotic arm, we have the robotic arm in the field, if you will. Very stable, we can remotely control this, so we can reach into it from a off-site, and all the data is processed in near real-time so you can visualize and respond. And one of the most important factors that you can switch from the monitoring mode to discrete sample mode. So if you see a detection somewhere that was not expected, you can go and explore that and resolve that.
Next. So continuous monitoring can be used not only for assessment and answering those kinds of questions, but we’re also using it to confirm mitigation, optimize it, and prevent exposure. So on the mitigation side, we can recognize the changes caused by building manipulations. That could be with ventilation. It can be isolating sumps and drains. It can be when you turn on the sub-slab depressurization system. Next. On the remediation side, we also can track things like fugitive emissions during aggressive remediation like ISCR, ISCO, thermal. And we can also see buildup of methane when you have the agent is causing in a reducing environment methane buildup.
Next. In terms of deployment, it’s very straightforward. It’s a gas chromatograph. We just need a small table with some temperature control. Sampling lines can be run several hundred meters away, small diameter tubing. O&M is traditional power. We’ve gone overseas and had to modify a couple of those things for those deployments, but it’s traditional. If you’re going to do a long term deployment, you would change the nitrogen out every several months. And you do need internet connectivity, and if you don’t have that on-site, we can easily bring a jet pack to the site.
Next. So here’s an image of the system. Many of you have probably seen systems like this. We’ve customized it a couple of different ways. Blayne is very crafty and pragmatic about this, so he’s customized a valving system to allow us to monitor from multiple locations. He’s done some really neat tricks to reduce the detection capabilities or increase those, improve those. And then everything gets sent to the internet automatically as well. And as I mentioned, we can reach in and control that system so we can modify the operational parameters.
Next, please. A couple field images. Here’s a gentleman that’s deploying some of the sample tubing. Again, we would deploy these, run that back to the staging area where we have the instrument. We would also get a GPS coordinate for that sample location, so that you can display that on a map through the web browser.
Next. Here are a couple of images whereby we ship the equipment to a facility. We ended up renting an RV and we can drive it around as a mobile lab, if you will. And in this case, you can see, we’re running the sample tubings out of the mobile lab or the RV that’s been modified to places that were…can you go back just a little bit…to different properties that were adjacent to each other, across the street from each other.
Next, please. The way we treat the data, you could track the concentration over time and space. We also track differential pressure and I’ll show you why that is, as well as temperature and other climatic barometric types of data sources. Next. The dashboard, we try to make this very intuitive so you can look at any location over time, the parameter you’re interested in. The stacked time series, I’ll show you some examples of that because that’s where you can make the correlations and look for these controlling factor impacts. You can look at contour and pinpoint images, moving averages, and set up alerts. Next. You could even trigger relays or samplers, so you can turn on blowers, etc. And everything is web based, password protected. If you check on a box, you can receive a daily report with the summary of all the statistics for the previous 24 hours.
Next. Here’s one example of the web dashboard for a particular project. So you see the spatial renderings that are in real time, or a selected time step. This is for TCE distribution. You can look at moving averages, those are the panels in the middle and on the right. You can look at time series for any location. And in the lower right side, you’re tracking when you’ve had an exceedance that triggered an alert. All that is downloadable. You can right-click and use the images however you’d like as well as grab all the data in an Excel-type of format.
Next. So when we’re looking at stacked time series, this is probably the most exciting way to look at this for me. You look for inflection points. In this case, we’re looking at tetrachloroethylene barometric pressure and differential pressure. I’ll dive into this a little deeper in a bit, but you can see that when the barometer dropped, you got an increase in that differential pressure. In this case, the increase means that the subsurface has a higher pressure than indoors and that Earth basically exhaled at that time and you got an increase in the indoor PCE.
Next, please. So the historical perspective is that indoor air concentrations might be a little bit dynamic, but not that great. And so a lot of people kind of assumed, with a time weighted average, that you’d get this flat line. Well, reality strikes when you start to monitor at a high frequency.
Next, please. This is a site where we monitored for about 10 days for freon, and you can see that there’s this beautiful pattern. When you see a pattern like that, it looks kind of like an EKG to me. We rapidly determined that this was being controlled by the HVAC system, and the changes in the differential pressure.
Next, please. Here’s a situation at a large industrial facility where we’re looking at it for seven days, and this is TCE. You can see the 300 microgram per cubic meter line. These were extremely dynamic responses that were happening on a daily basis. Next, please. In actuality, you can see that within an hour or two, you would get changes that were greater than 50X in some cases.
Next. So you can expedite these assessments. You can see the pattern right away. You can rapidly determine whether it’s from VI or an indoor source, and you can tie that to controlling factors. You can know how often it’s above a screening level so you can use that for risk assessment. And then you can answer these key questions right away as well. Next, please. Again, that data pattern, spatial and temporal, is the opportunity to resolve those questions.
Next. Okay, I’ll get in a couple more quick examples here. This was a relatively complicated site because, as you can see, we’re looking at barometric pressure, tetrachloroethylene and trichloroethylene, over a couple of days, two and a half days or so. It was a former drycleaner. So we obviously expected tetrachloroethylene, but we didn’t really expect TCE. Well, you can see the inflection point between barometric pressure and PCE, which indicated to me that as the barometric pressure rose, we got flux moving downwards, so we got a drop in tetrachloroethylene. Maybe that’s a VI indicator. But on the TCE side, when the facility was closed, the C there, the C levels, all of a sudden, you saw a rise in concentration. As soon as the facility was open, you got a drop in concentration. The building was essentially acting like a flux chamber. Next, please. So I would interpret that to be vapor intrusion for PCE, but there was an indoor TCE source.
Next, please. This is a wonderful example here. This was that one I showed you where you got greater than 50X change. On the top chart, you’ve got grey is barometric pressure, blue is trichloroethylene concentration, and you can see that when there was a drop in barometric pressure, the Earth basically exhaled, and you got a rise in indoor TCE. If you look at the bottom chart, you see the differential pressure, again, positive differential pressure in this case means that the subsurface has a higher pressure than indoors. So what we’re seeing here…next, please…is as the daily barometric pressure changes, you get a differential pressure and that results in the vapor intrusion. So the implications associated with the timing for sampling is tremendous.
Next, please. So because of that, we have now built our own differential pressure systems that can wirelessly transmit the information to the web so that you can couple that data. And you can couple it with weather activities as well as concentration distributions.
Next, please. This is an example where folks optimized a sub-slab depressurization system and they wanted to, in real time, see the impacts of that. And so it’s readily obvious to the most casual observer that when the system, the mitigation system was engaged, it was effective in all the rooms that we were monitoring, all the locations.
Next, please. This was from a super fun remediation site where we…there was a resistive heating so we were looking at thermal, and we started monitoring before the energizing of the probes. And as soon as things started to heat up, we started to see a rapid increase in an adjacent warehouse in TCE.
Next, please. Fortunately, people were alerted immediately, and the vapor extraction system was adjusted and they knocked that out and resolved that issue, while everybody was on site and you can see that in near real time.
Next. Okay, this is one of my last examples here. This was a facility where the building was for sale and it was a furniture manufacturing tenant. And the owner tried to sell the building and was getting a low offer, by $2 million less than asking price. There have been previous data collected. They knew there was subsurface TCE and PCE, and indoors, they had seen mostly TCE with a little PCE. So we started to monitor after a shift was done in the nighttime. And you can see in the early times, there was not much TCE observed. But then as soon as the machines fired up and people started to work, we start to see these large hits. If your eyes are good, that’s over 200 micrograms per cubic meter. And then it dropped off when the shift was done. So Dr. Hartman walked around with the consultant to try to figure out what people were actually doing because the spatial distribution was ubiquitous, it was everywhere.
Next, please. They identified these cans of silicone spray that were being used in their process. Next, please. When you look at the label, TCE was not listed. It didn’t even say other materials on the labels at all. But Blayne got a very clever idea. He said, “You know, we have the GC here, let’s analyze the spray. Next, please. So here you have the chromatogram, where he conclusively demonstrated that TCE was in that material. So they got rid of that material and, lo and behold, the TCE signal dropped out in that building during the monitoring.
Next, please. This was a rousing success. So we had multiple lines of evidence to conclude that there was no vapor intrusion. The earlier methods, they just had to keep doing it over and over and over again and they weren’t really able to answer the questions, but we were able to accurately source that and resolve these uncertainties. So they were able to also protect the occupants. In that situation, there were a lot of young women. But what happened that was most exciting is as soon as we were done, the owner of that building received an offer for full asking price. So in three field days, a single mobilization, he basically made $2 million.
Next, please. Here’s my last example. This occurred less than two weeks ago. There was a room in a facility with multiple rooms, and one of the rooms had very high TCE. In fact, it exceeded a thousand micrograms per cubic meter in some of the readings. Well, we were able to convince the folks to turn the HVAC system off because we were seeing some strange patterns everywhere. And so here we’re looking at one, two, three, four, five different locations not in the room that we suspected was a potential source. The ventilation system was off. And as soon as it turned on, it was distributed from that room, from the hot spot, throughout the facility. You can see that rapid increase in concentrations. Next, please. And simultaneously, in that other room, we saw a drop, from greater than a thousand to less than 300 micrograms per cubic meter. So the building manipulations with the live real-time high resolution data helps you get a picture of what’s really happening at that facility.
Next. Okay, last concept here. We’ve worked at a lot of sites where we’re talking about large shallow groundwater VOC plumes that are underlying many, many structures. And I know that there’s reluctance to go indoors because of the potential for indoor sources. But since we can identify those sources now, I submit to you that we can rapidly screen these neighborhoods or these areas with these large plumes. In the discrete sample mode, we can process about 50 analyses per day. We’ve actually exceeded that before. And then when we monitor, so we go to monitor to refine our conceptual site model or because there’s some exceedance of a threshold criteria that we’re interested in, for instance, you want to determine the reasonable maximum exposure or identify an indoor source etc., you can monitor and when you’re in monitoring mode, you can process over 150 analyses per day. But you get a rapid answer to these questions and then you can expedite the exposure prevention and mitigation steps that you can take.
Next, please. So here’s again a picture that I showed you before. On the lower left, you can see these discrete samplers. This takes a few seconds to collect the sample and about 10 minutes to run. Go back, please, if you can, sorry about that. And you can see also, if monitoring is warranted, then you can then start monitoring to answer those other questions.
Okay, next slide, please. I’m going to wrap this up now. This technology exists for monitoring, response, and to confirm that your response has met your objectives. Next. Again, the data pattern is that opportunity. It’s the most important takeaway I hope you get. I know I sound like a broken record but it just jumps out at you. Next. Because of those data patterns we’re generating, within a single mobilization, we can answer these critical questions regarding whether a risk exists, whether you need to respond to TCE short term risks, whether there’s indoor sources, identify those, where the vapors might be coming into the building, or whether you have preferential pathways from sewer connections, etc. And then you can evaluate and optimize mitigation or remediation systems. For brownfields, this is very helpful when you want to try to quickly resolve questions associated with whether or not there’s going to be a risk, and then as I mentioned, the large neighborhoods, we can do a combination of discrete screening with continuous monitoring to then quickly answer the questions. Next, please. This, I am seeing folks save time, save money, prevent exposures and liability.
Thank you very much.
Oh, let’s go back. Wait, wait, wait, go back a little bit and we’ll wait for that one. Maybe go to Tom’s first.
Tom: All right. Thank you, Mark, and thank you, Blayne. So I want to take a brief moment to just kind of…for the folks that are listening in, you might be familiar with Land Science, but if you’re not, Land Science is a global leader in advanced technology for contaminated site remediation under Regenesis when we focus on vapor intrusion. If you’re dealing with this continuous monitoring that you just heard or some of the other updates that Blayne had discussed as far as vapor intrusion is going, what are your options? Land Science, we work with federal and state and local regulatory agencies on providing these viable solutions, so not just a tangible concept, but a solution to how do we get to what the most important thing is, protection and making sure that vapor intrusion is not happening.
So at Land Science, we don’t just offer a vapor barrier, which I’m going to get into, but we also offer design assistance. So the folks that are listening, if they are intimidated or if they have a in-depth site that they need assistance with on, not only maybe regulatory approval but maybe client approval, we can help assist with those designs. We also have a in-depth QA/QC process for our vapor barriers as well as our design. We also have certified applicators and certified inspectors so that what that meaning is we have a rigorous training that we put our applicators through so they understand how to meet our requirements for our barriers. And we also provide onsite support.
So going into more of the tangible concepts of what Land Science offers, if you weren’t familiar with Land Science until last year, we were offering two types of products for solution, Geo-Seal and Retro-Coat. We are still absolutely excited to be able to provide those solutions. But as an innovative company, we decided to see what else we could do as the industry was requiring and asking for different types of solutions for situations, because every building and every situation could require a different look at the situation.
So with that being said, Geo-Seal has been our situation of what we’ve provided for many, many years of millions of square feet of success. It was the first concept that we brought to the market where we blended HDPE and a spray membrane. As you can see here, we blended that durability concept with a chemical resistance, and we had a diffusion coefficient that was 685 times less than just the spray applied that first hit the market many years ago for the methane situations that we were dealing with here in California.
And the other aspect that we provided, probably about eight years ago now, is Retro-Coat. And Retro-Coat is a unique solution. When you have a site where possibly you’re looking at you have a vapor intrusion risk, let’s say you did your continuous monitoring and you say, “Oh wow, this is what we’re faced with.” What are you going to deal with? Do you want to do sub-slab depressurization? Possible. But do you have that impermeable barrier that you can then lean on, so let’s say, if you did find that when the SSD is not working, you don’t have the VI [inaudible 00:46:22]. So Retro-Coat gives an option of being able to give you that solution for vapor intrusion. It’s highly chemical resistant, we have hundreds of sites across the nation to where they actually drive cars and forklifts on it. It contains no VOCs, which is highly important. Don’t you want to have a layer that doesn’t off gas VOCs? And multiple regulatory agency approvals, and actually recommendations, throughout the industry.
But as I said earlier, we, as an innovative company, recognize that there’s there was more need in the market, there was more need in the industry. And so we offer TerraShield, Nitra-Seal, and MonoShield. That was launched in 2019, just last year.
TerraShield, it’s unparalleled chemical resistance. So we have sites where we possibly have [inaudible 00:47:08] or [inaudible 00:47:09] situation in sub-slab situations, then we are dealing with a severe VI potential risk. So this TerraShield offers a dual-metalized film and we also blended a new Nitra-Core. A Nitra-Core is adding, basically, thinking about like latex versus nitrile gloves, more chemically resistant. So it’s an improvement of that spray applied core. So we’re creating a more robust chemically resistant barrier in a sandwich-like fashion.
Nitra-Seal. So similar to what we’ve provided and continue to provide with GeoSeal, we just basically decided to offer Nitra-Seal as an option and it’s taken to a great success. We’re seeing that an option of blending HDPE with the Nitra-Core and giving just a little bit more chemical resistance. For essence of time today, I’m not going to get into that chemical resistance, but we do have it on our website, at landsciencetech.com that you can go into and look at some of the success information that we would not only internally, but externally been able to identify for TCE and benzene, etc.
And MonoShield, this one is a unique aspect in the marketplace that we’re finding where there’s large warehouse developments, maybe they have a low-level contaminant and they do identify that there’s a potential VI, they wanted to have that solution, that peace of mind. So this is a single layered barrier that’s laid out. It is a metalized film, blended as you can see, all those separate layers are actually come as one layer as it rolls out, but it is sprayed seam with our Nitro-Core that I just mentioned earlier, and it gives an option opportunity to create a more rapid installation and it gives still that VI protection. As you can see here from a third-party testing, our MonoBase, which is the base layer of MonoShield, has a diffusion coefficient for benzene of 2.55×10 to the -15. If you are needing that for a regulatory approval, we’re more than happy to provide a technical sheet for you, or any type of write up that’s necessary as you’re putting this into your specifications.
And last, I just wanted to wrap this up with Land Science stands behind our products. And what we look at this is we offer industry-leading vapor intrusion barrier warranties for a slew of all of the products you see from what I’ve just discussed. So it is a sliding scale depending on the site-specific situations, to maybe even the banks’ or the clients’ requests. So if you have inquiries about what type of warranties we can offer for you on the different barriers, I encourage you to get ahold of one of the Land Science sales managers, technicians or the engineers, and we would gladly give you a overhaul of, kind of, what we’re looking through and, kind of, what type of warranty and what would be this best barrier in the suite of barriers that we offer.
And with that, I’m going to turn it back over to Dane for questions and answers.
Dane: All right, thank you very much, Tom. That concludes the formal portion of our presentation. So at this point, we’d like to shift into the question and answer portion. Before we get into this, a couple of quick reminders. First, you’re going to receive a follow-up email with a brief survey. We really appreciate your feedback so please do take a minute to let us know how we did. And also, right after the webinar, you will receive a link to the recording as soon as it’s available.
All right, so let’s circle back to the questions here. Let’s see, the first question here is one for Blayne and it is “How is wind speed a factor for indoor vapor intrusion?”
Dr. Hartman: Well, it’s the old Bernoulli effect, if you remember that. It causes airplanes, of course, to lift. So when you get wind blowing over a structure, you’re going to get, on one side of the structure, a pressure differential versus the other side, which can essentially create an updraft inside the structure.
Dane: Okay. Let’s see. Here’s a question for Mark. Mark, the question is “Is the continuous monitoring system available for petroleum, for example, VTECs sites? Is it suitable for residential buildings? ”
Dr. Kram: I’m going to let Blayne actually answer that one.
Dr. Hartman: It can be used on VTEC sites. We have to be careful with VTEC sites that we can get resolution of benzene or speciation of benzene from cyclohexane, but yes, it can. And the second part of that question was the residences. Yes, we’ve used the system on residences. Quite often, it’s a little pricey to use on a single residence, but in the pictures Mark showed, they were in a neighborhood, they were able to run tubing to several residences, three or four or five at one time, so that made it cost-effective. We’ve also been in large residences with lots of rooms where it was cost-effective. So yes, we have done residences, but most often, we do commercial structures.
Dane: Great. Let’s see, here’s a question for Tom, and it is “Is Land Science working on any vapor barrier technologies that can work for mercury? ”
Tom: So yeah, that’s a great question. The barriers that we provide, especially the metalized films, are performing at such a high level for preventing vapor intrusion that we’re taking it to that next level in taking a third-party lab to do the analysis for mercury. And we’re pretty confident, once we get the data back, that we’ll be able to provide that quantitative information for regulatory approval or just industry requirements. But in the interim, we do have a internally published letter that we can provide where it indicates why TerraShield and MonoShield would be a viable barrier for the mercury vapor intrusion situation.
Dane: Okay, thank you. Here’s another question for Mark. And it is “Has continuous monitoring system been installed in sub-slab or soil gas applications as opposed to just indoor air? ”
Dr. Kram: Yes, it has. What we do is we oftentimes are asked to look at the sub-slab at the same time as indoors. And so we work a few different tricks into that. Obviously, in the sub-slab, we would expect a higher concentration, and so we may try to run a blank before we start to monitor indoors following a sub-slab sample, but yes, we do that.
Dane: Okay, great. Thank you so much. Let’s see. Here’s another question for Tom and it is “Is a 20 HDPE barrier still considered protective or should 40-mil barrier be used?”
Tom: So that’s a great question. Many years ago, the U.S. EPA issued a memorandum and a lot of state regulatory have also, kind of, followed suit. With 30 mils, both on the construction aspect and scientific aspect for diffusion, has been identified to be the more appropriate barrier minimum, hence it’s kind of why we rolled out our MonoShield, and when we designed it, we brought it out as a 30-mil barrier, meeting not only the construction standard, the integrity of being able to hold up to the construction aspect of the building, but also diffusion tests lying towards the solution being 30 mils or thicker.
The other thing they need to think about is if you’re looking or considering 20 mils, you have to think about how protected are you’re working on those seams. A lot of the 20-mil systems out there are taped together. And if you’re only as successful as your weakest link, the tape is your weakest link, and you may still have a concern in those tape aspects in the 20 mils.
Dane: Okay, great. Thank you very much, Tom. Here’s a question for Blayne. This one’s a little detailed, so please bear with me here. “Giving the example of, let’s say, you’re sampling indoor air for PCE, TCE and vinyl chloride from impacted groundwater, but the facility uses various VOC products, so you know the VOCs are in the air. Can you keep a low reporting limit for vinyl chloride, or does the abundant VOCs in the air mask the vinyl chloride, erase the recordings if it’s too high?” [inaudible 00:57:01]
Dr. Hartman: Not at all, because the analytical system brings in samples from the outside and does not see any air from the inside unless you want it to, unless you want to monitor some inside rooms. So the system brings in the air through the tubing. Now, if indeed in the building itself, the whole building has VOCs and you’re trying to resolve it from, say, subsurface VOCs, then the trick there or the key there is to look at the ratios. And Mark showed you one example, the furniture example, where there, we had sub-slab data that had both TCE and PCE, but in the indoor air, we only had TCE. Well, if it was coming from vapor intrusion from the subsurface, we should have had both. So we’ve had, I would say off the top my head, five or so cases, where by looking at the ratio of what’s below, a compound ratio, and comparing it to what we’re seeing inside, we were able to resolve the fact that it was coming from indoor versus sub-slab or the reverse.
Dane: Okay, thank you very much, Blayne. So here’s a question for Mark. And it is “Can continuous monitoring be used for methane monitoring only and having the alret system set up? ”
Dr. Kram: Yes, it can. Blayne actually could probably answer that in greater detail as well, but it certainly can. And the alerts can be set up to be universal, meaning that you have, say that you want to look at 10% of the LEL anywhere, or you can look at a specific location, you can set up a different rule for that. So it’s very flexible the way it’s been designed. Blayne, I don’t know if you want to add to the detection of methane at all.
Dr. Hartman: Only to say that the system can measure very, very low, down to the ppm level, or can measure very high, up at the percent level.
Dane: Okay, great. We have time for one more question. This is for Tom. And the question is “Can any of the vapor barrier barrier products Land Science offer be applied over an existing floor or does the existing floor need to be removed, the barrier applied to the subfloor concrete base? ”
Tom: So yeah, the brief answer is yes. As you’re seeing some of our slides here, the bottom barrier that we offer, Retro-Coat is applied to the concrete itself. It is not just painted on though. It is a process where we scarify the concrete. So we do encourage that if you have a site where you’re looking at possibly putting a barrier on top of the concrete that we do a site walk and one of our certified applicators can go through that process with you.
The other barriers can go on top of a concrete, however they are not designed to be left exposed. So if we are going to use the other sub-slab barriers, we have installed, in some cases, the barrier over a concrete slab, but then a protective concrete slab has to be installed over the top of that, something like a or whatnot. But we would first look at look at using that Retro-Coat as a solution.
Dane: Thanks, we have some more time, so one more question here. This is for Blayne, and it is “Are there any specific study that show radon and VOC attenuations correlate? ”
Dr. Hartman: Well, the best one is to look at the Indianapolis test house that EPA’s been involved with for a number of years now. In fact, whoever asked that question, I just asked the EPA’s research people for cross plots showing radon versus, in that case, it was perc to see how well they correlate. So those test plots were actually just sent to me just yesterday. So ask me again, whoever asked me this question, email me in a few days after I’ve had a chance to look at them. I will say however that EPA headquarters is very much promoting the use of radon as a surrogate, so that would make me think that they have concluded that the radon and the VOCs go together. Again, I haven’t looked at the actual plots myself. I will do that. As of right now, based on EPA’s indicators, radon being one of their indicators, it would lead me to think that there must be a decent correlation between the two.
Dane: All right. Thank you very much, Blayne. So that’s gonna be then of our chat questions. If we didn’t get your question, someone will make an effort to follow up with you. For more information about Dr. Hartman’s vapor intrusion services, you can visit hartmaneg.com. For more information about continuous monitoring software from Groundswell Technologies, please visit groundswelltech.com. And if you’d like to learn more about vapor intrusion solutions from Land Science, please visit landsciencetech.com.
Again, thanks to Dr. Blayne Hartman, Dr. Mark Kram, Tom Szocinski , and thanks to everyone who could join us. Have a great day.