Balancing the Costs of Active Cleanup and Long Term Stewardship During Remedial Planning

Jeff: Great. Thank you, Dane, and good morning. Good morning, everyone, or afternoon, depending on where you may be. Thanks for being here. I’m guessing that most of the audience today is consisting of consultants and environmental professionals. So although the concepts I’m gonna talk about are pretty basic, I’m gonna allow myself to use our own style of language that we’re all used to hearing with the acronyms and terms that we commonly use. I hope also that there are some representatives of responsible parties here, too, because we are gonna talk about some things that I think they would find really interesting.

There we go. Thanks. So, again, I’m Jeff Carnahan. I’m a geologist. I’ve been Environmental Consultant for right at 20 years. I’ve been very fortunate to have worked on a nice variety of sites including retail petroleum, platers, dry cleaners, MGPs, steel mills, refineries. I do wanna state real quickly that I’m a geologist. I’m not an attorney like most environmental consultants. However, I’ve worked very closely alongside some great environmental attorneys during my career which has given me the perspective that I have and that I’ll be talking about today regarding risk and liability, okay? Any responsible party with an environmental problem, please retain a qualified environmental attorney to help you out with those issues.

Okay, so there’s that. When I joined EnviroForensics about eight years ago, I became part of a team of experts managing a large number of chlorinated solvent releases, primarily a dry cleaner sites. Now, many dry cleaners are small businesses who have to rely on their past insurance assets to fund the work, and it’s a part of our jobs to help them navigate that process as well as clean up their problem.

When you get to know someone personally who’s struggling with real world financial and legal consequences that arise from being an accidental polluter, it’s really not just about an academic exercise or accounting exercise anymore. You really wanna help them get to the end point of their problem, and I mean the real end point. It’s important to keep in mind the regulatory closure is really only an interim step in the process of protecting our clients from risk, that’s why we have to look at post-closure costs and long-term stewardship in such great detail.

Real quickly, I wanna say thanks to REGENESIS for the opportunity to present in this forum. Like many of you, I started using ORC, a petroleum site, almost immediately after getting my first job as a consultant. It’s been really fun to watch them grow and continually release better and better products as the years have gone by, really helps us environmental practitioners help our clients and be more successful.

So as you know, the driver for meaningful environmental cleanup is cercla liability, right? RPs can either earn that liability by having a release during their time of operations or they can inherit that liability via property or business acquisition. Inheriting a costly environmental liability sometimes doesn’t seem fair to our clients, it doesn’t feel right, but those are the rules because somebody has to be responsible for paying for it.

Brownfields Programs and the all-appropriate inquiry process can provide some relief which is great for business. It’s great for promoting redevelopment, but they don’t promote a meaningful site cleanup beyond exposure pathway elimination in most parts. That’s bad for the overall status of the environmental degradation of the plane, right? If we only eliminate risk and don’t ever clean up, our ancestors will be walking around on a balloon full of contamination someday.

Now, everyone agrees that the number one goal should be preventing or halting human exposure to harmful contamination. But the methods and regulations related to planning for continued risk elimination into perpetuity are still foggy at best. When responsible parties actually accept the need to clean up and restore the environment in addition to controlling risk of exposure, the financial burden increases dramatically and so does the importance of balancing the remedial effort with the anticipated future costs.

For example, the vapor mitigation system on this structure to your left is not nearly as expensive as the remedial effort indicated on the right. Both efforts could be used to eliminate an exposure pathway and result in a regulatory closure. The thing is, however, the cost of that same remedial effort may seem small if the vapor mitigation system is not maintained and that same structure has a different use in the future and a meaningful remedy still has not been performed. When dealing with persistent recalcitrant compounds like chlorinated solvents like perc dry cleaning solvent, the threat of future exposure stays around a long time and could become a reality if engineered or institutional controls should fail or be abandoned. So out of this concern, the concept of long-term stewardship has been developed over the past several years as the means of ensuring that risk remains under control when harmful concentrations of contaminants remain in place after regulatory closure.

EPA gave us a look at what a long-term stewardship plan might look like when they released their institutional control implementation plan or ICIAP guidance. As a matter of fact, Attorney David Gillay with Barnes and Thornburg talks specifically about the ICIAP during a webinar hosted by REGENESIS way back in 2013. So this has been around a while. This has been under development for quite some time. Most recently, the ICRC gave us an online tool to better plan for long-term stewardship. That’s available on their website. I recommend that you go and give that a look. I think you’re gonna find it very helpful for future planning for long-term stewardship. So there are a lot of regulators working on a sustainable process to document, track, and enforce long-term stewardship needs for risk-based environmental closures. That’s great. But remember that a well-crafted LTS program costs money, real money. That same money might be better spent getting actual contaminant mass out of the ground.

So there’s the dilemma. So a dilemma is defined as a choice between undesirable outcomes or making a choice that one doesn’t wanna make. Do I spend more money now on cleanup or do I spend more money later on LTS? Cleanup costs are inversely proportional to long-term stewardship costs. As more cleanup is performed, the need for LTS is reduced. Although LTS costs may ultimately be larger than initially conceptualized, common remedial decision-making will typically result in a strategy that relies heavily on LTS following a limited remedy.

Another cost component that’s often overlooked however is the potential legal damages that maybe occur when leaving contaminant mass behind. Where the cleanup effort is kept minimal at the direct expense of future LTS costs and liabilities, quantifying this future risk component is difficult due to inconsistently enforced and not yet fully defined LTS requirements. They’re working on it. We’re not yet fully enforced. Although there’s not an exact science of predicting future third party liabilities, those liabilities exist, but they’re really hard to predict.

Since these factors are difficult to put price tags on, they’re more commonly sidelined during discussions of total project lifecycle costs especially when there are multiple financial stakeholders involved with making those decisions. Each of those financial stakeholders may have their own hire consultants and they may have different short-term objectives. The responsible party is probably looking out for their total liability while purely financial stakeholders may be focused more sharply on the shorter-term goal of regulatory closure. But as we know, regulatory closures are only a milestone.

We found that a very useful exercise is compartmentalizing the cost components of the project risk lifecycle prior to designing our recommended remedial approach. This completely changes the dynamic of remedial planning. Spending known dollars today to remove mass is definitely a safer bet than gambling for a best case long-term liability scenario. Validating the real potential of significant LTS and future legal risks tips the balance back toward more contaminant mass removal which reduces those long-term costs and also has a positive side effect of promoting a higher degree of environmental restoration.

So now, let’s look at a few examples of this decision-making process and the results, okay? Please note that the examples I’m using are real sites that are in different state-led cleanup programs. The LTS costs were assigned based on the applicable requirements or standards or lack of requirements or standards that were in place in that state at the time the remedial decision-making was being undertaken. Also, the values assigned to future liability were prepared in cooperation with the client’s attorney following their full analysis of legal risk factors. These sites aren’t yet closed, but the remediation is in place. Now, I wanna talk about three specific examples and kinda walk through the decision-making process.

So, what we like to do is use a risk evaluation and point of exposure assessment tool during remedial planning. I’m sure everybody has seen something like this. This one’s pretty cartoonish, but let’s walk through it quickly because it really helps identify where remedial efforts and long-term stewardship efforts may be needed in the future. So we have the impacted soil reservoir with mass fluxes via the direct contact exposure to the receptor, migration to groundwater pathway, and a vapor source directly to the vapor phase reservoir, right? Groundwater fluxes to the receptor via ingestion exposure pathway among others and to the vapor phase reservoir due to off-gassing of groundwater impacts. Of course, the primary flux from the soil gas reservoir is through the inhalation pathway as a result of vapor intrusion. The game is to try to eliminate all arrows to the receptor by eliminating exposure and/or those reservoirs.

Okay, so here, we see a groundwater plume beneath a mixed commercial and residential area. Businesses to the west, private residences to the east, the RPs property is at the very north of this plume. I hope that comes across and everybody can see what we’re talking about. We’ve got commercial, we’ve got residential, we’ve got a lot of potential threat not only for the exposure but also, we’ve got several properties being impacted there as you can see that might lead to someone thinking that their property could be diminished in value at some time in the future.

Walking through the conceptual site model. The site was fully characterized at first, and what we have is impacts present on site, in vadose zone, above the direct contact thresholds, and the migration of ground water standards. The groundwater plume is expanding, contributing to vapor intrusion exposure issues. The vapor intrusion pathway, the vapor intrusion reservoir, if you will, the soil gas reservoir was resulting in a scenario where mitigation was necessary at the source area and downgradient residential structures. So there was the threat or the direct connection of the vapor intrusion exposure pathway.

So here’s that exposure assessment model for this example, all reservoirs are full, all fluxes and exposure pathways are complete or potentially complete. So that’s the starting point for this decision-making process. So as we looked at potential remedial strategies for the site, we saw a couple of different approaches. There is more than two obviously, but for demonstration purposes, we’re gonna limit it to two here. Remedial strategy A included a soil excavation to cut the head off the snake and promote future plume stability and place an institutional control for groundwater usage. You’re gonna see that one a lot. Because when groundwater plume gets below a concentration that it may not make sense to make more remedial efforts, we have to impart that institutional control. Because as we all know the MCL for a perc is five, and that’s really hard to get.

So strategy A also included installing and maintaining vapor mitigation systems at the affected structures. So what you notice is we don’t have any groundwater treatment and no vapor phase treatment. With remedial strategy B, for this example, we could add a groundwater treatment component which would stop off-gas into the vapor phase, knock out the rest of the exposure pathways.

So here’s how that looks from a cost analysis. Soil excavation remedial strategy A, 45K. Groundwater treatment, we’re not gonna do any, zero dollars. VI mitigation, well, we’re gonna have to take care of those residential homes and we’re gonna have to take care of those commercial homes with vapor intrusion mitigation systems, 100K. Long-term stewardship’s been estimated to include both VI monitoring, long-term, as well as groundwater monitoring because remember, we’re not touching this big plume, $445,000. Future liability, again, we’ve dealt with the attorneys. We’ve tried to determine what type of potential long-term legal liability may result from leaving these conditions in place so we assigned a pretty conservative $95,000 there. Again, these are not bodily injury claims that we’re anticipating. It’s typically got something to do with property value. Total for remedial strategy A, $685,000.

So if we wanna augment that for a potential analysis remedial strategy B, soil excavation stays the same, 45k. Groundwater treatment, this time, we want to address that groundwater plume and see if we can knock the contaminants down, and what would that do to the rest? Well, you saw in the exposure model previously what would happen if we got rid of the groundwater treatment. VI mitigation goes away. Long-term stewardship essentially goes down to nothing although, of course, some of you guys are questioning that. Of course, there’s an IC component of maintaining that institutional control. But as far as this analysis, it doesn’t really come into play too much. Future liability is just a fraction of what would be because we’ve essentially eliminated exposure pathways to most of the outlying properties. Total there, 265K.

Remedial strategy is implemented. Again, this remedial strategy has already been put into place. Soil source area removal via excavation, that was completed. Groundwater, we treated the plume directly with REGENESIS products, 3DME, CRS, and BDI, knocked that plume down. Vapor intrusion pathway elimination via that groundwater treatment, and the anticipated LTS is essentially institution control monitoring for groundwater usage.

Early results, this is what this thing looks like. We got pre-remediation to the left. I chose a couple of monitoring wells within the area of highest impacts, one being up near the source area, one being a little further downgradient. As you can see, the red line is perc, the other are our daughter products, and you can see that initially as soon as we injected the cocktail in January of 2016, you saw perc take a dive in both wells. Daughter products increased as you’d anticipate and perc has been pretty much flatlined ever since downgradient and most recent results were non-detect. So I think that’s a great result. We look forward to that trend continuing.

Wrapping up example one, project lifecycle cost, total investigation plus remediation, about 1,000,450. Cost of active groundwater remedy, 200K. Lifecycle cost savings due to active ground water treatment $420,000. I think this is a great example. I think it really demonstrates my point very clearly. By spending an extra $200,000 which, if you really look at the total investigation and remediation, is just a small fraction of that, you are incurring significant project savings.

So here’s my second example. This one, we’re gonna look at a project pay-off from the installation and operation. It’s a little vapor extraction system. Don’t worry, REGENESIS, we’ve got a little product in there for you, too. This figure shows a large soil gas plume residing within a deeper sand vadose unit. Note the building to the southwest, that’s a seven-story multifamily residential housing unit. Numerous residential structures overlying the plume to the north. Concentrations, as you can see there, really high.

Contaminant conceptual site model, notice I’ve got two soil reservoirs, one shallow soil, one deep soil. Shallow soil impacts are present in excess of direct contact thresholds. Deeper soil holds a very high vapor concentration. Shallow is actually a finer-grained unit, more of a loam, deep soil is actually a pretty well-sorted sand. Groundwater plume, stable and dilute, not above what we call VIGWSLs via groundwater screening levels here in Indiana, meaning it’s not causing a big problem for vapor intrusion concerns but definitely above the maximum contaminant levels. Vapor intrusion, exposure pathway was complete at numerous offsite properties with basements.

So again, let me point out that even though I may say that no further vapor mitigation systems are necessary as a part of the remedy, that doesn’t necessarily mean that vapor mitigation systems weren’t installed as an interim measure to eliminate risk during the investigation process.

So here’s how that scenario looks as our exposure assessment model. Note the lack of significant flux from groundwater to vapor phase. The massive soil gas plume is fed mainly by the deep soil impacts. So our two strategies for consideration here, demo the on-site building, perform shallow slow excavation and place a groundwater usage restriction. Again, there it is. Mitigate the VI pathway. This would leave that soil gas plume in place and could potentially cause problems in the future.

Strategy B, we considered adding a soil vapor extraction component to knockout VI concerns altogether. So as we consider that, here’s how those numbers look. Demo and soil excavation, about 265. Groundwater treatment, none anticipated. VI mitigation, a few hundred thousand dollars necessary to make sure that everyone was going to be kept safe not only in the present but also in the future. Long-term stewardship, you know, we’re gonna anticipate a couple hundred thousand dollars there, both ICs and VI, long-term O&M. Future liability, that one we’re a little concerned about here. We had several offsite properties. We had that big multifamily, and, you know, a quarter million dollars we had for future liability. Total, a little over a million.

So as we looked at the remedial strategy B, note that although it’s much cheaper, almost all the money gets spent in the first couple of years, whereas in strategy A, half the cost get deferred until later. So if you can think back to what I said about gambling, if you will, today’s dollars are a better bet when you removing mass than tomorrow’s dollars, potentially, when you’re dealing with unknown liability. So demo soil excavation, soil vapor extraction, $265,000. Add in 450 for the SVE. Groundwater treatment, none spent. VI mitigation, no additional mitigation necessary. Long-term stewardship, since we don’t have to deal with VI and we can focus on our institutional control for groundwater, we only put in 15K for that for analysis for purposes. Future liability, again, a fraction of what we had with our previous option. Totaling here $760,000.

Remedial strategy as implemented. Shallow soil, buildings knocked down, source areas soils, stabilized in place with REGENESIS. There you go. PersulfOx, worked really well. And then excavated as non-haz. Excavated and disposed of as non-hazardous material. Deeper soils, installed the SVE, fired it up, operated for a couple of years. Groundwater institutional control, vapor intrusion, again, pathway elimination via soil excavation and treatment, and the SVE elimination of that pretty significant deeper sand reservoir. Anticipated LTS, just IC monitoring for groundwater usage.

So just to demonstrate, if you’re thinking earlier that those SVE costs were pretty high, they were. But here’s our effective radius of influence from that system. You know, we really appreciate all the support and cooperation of all the financial stakeholders in getting on board with this because I think it really ended up giving the client a great conclusion here. It was a big cost, but they check out these results.

Here’s how that project laid out. Project lifecycle costs, you know, and again this is not, you know, everything of soup to nuts, I think they call it. It’s not everything encompassing, but for the major cost components for analysis, total investigation remediation, 1.6 million. Cost of active deep soil SVE remedy, 450K. Lifecycle cost savings due to active groundwater treatment, 250. Now, $250,000 is a smaller savings for a larger investment in the first example, but a quarter million dollars is still a lot of cash and it’s 15% savings over the project lifecycle.

So firing right through, sounds like we’re gonna have plenty of time for questions and answers, but my last example here, I wanna lay it out just a little bit differently. Here, the third example involves variable degrees of groundwater treatment. So the first reservoir, soil. CSN tells us that sandy vadose zone impacts were present directly or above direct contact levels and the migration of groundwater thresholds, so both of those fluxes are present directly contributing to on-site and off-site VI exposures.

Groundwater, pretty big plume, pretty complex plume, shallow impacts on site at a depth of around 50 feet below grade. We had a diving plume downgradient at depths of 150 to 250 feet below grade. Problem is that that plume at depth during the middle reaches wasn’t causing any particular VI concerns of the overlying residential neighborhood, but down near the leading edge, that plume actually started to upwell up underneath the smaller portion of the residential neighborhood. Vapor intrusion, therefore, so we have pathway was complete at the site, at some neighboring municipal buildings and downgradient commercial and residential structures. But again, potential future risk downgradient for VI.

So here, I’ve actually got two components of the risk evaluation and point of exposure assessment. I’ve got a near-source and a downgradient. Near-source, as you can see, all fluxes and exposure pathways were present and causing problems. Downgradient were focused primarily on the ground water and the vapor phase. First strategy included a measure of treatment for each of the major mass reservoirs XXX and a groundwater use restriction at the source area. Only exposure control elements, downgradient, okay? So the first remedial strategy did not include any consideration of groundwater treatment downgradient.

For evaluating LTS needs, we modeled plume behavior based on our first remedial strategy for timing. So that’s gonna include a source area injection. That’s the red line you see, basically, a source area injection infiltration gallery and a near-source, but yet downgradient cut-off barrier. And as you can see, that as modeled, that was gonna take about 16 years for that plume to degrade to the point that we modeled it to.

Second strategy, we added additional groundwater treatment consideration downgradient to eliminate future concerns of VI. Okay, so this time, we’re gonna go ahead and kick out the VI or kick out the groundwater pathway downgradient thus we’ll eliminate any vapor phase PCE problems down there. And as you can see that when this strategy was modeled, time frame was basically cut in half. Again, everybody, I understand these are models, but for planning purposes and for making strategic decisions, I think these are great tools in order to help us make these types of decisions.

Here’s how the numbers play out. Remedial strategy A, soil excavation plus SVE, 50K, $380,000. Source groundwater treatment, that’s a pretty high price tag, $800,000. VI mitigation, $400,000. It’s gonna be a lot of vapor intrusion both downgradient as well as up near the source reaches of the plume. Long-term stewardship up here, 16 years vapor mitigation system, groundwater monitoring, $825,000. You get a lot of vapor mitigation systems and you get a lot of long-term stewardship costs associated with that. Future liability, pretty significant, $375,000. Totaling a little over $2.8 million.

Now, remedial strategy B. We’re the same in the vadose zone. Soil excavation plus SVE, source and downgradient groundwater treatment in this model, totaling $1.4 million. That’s a pretty decent chunk and that’s money that you’re spending pretty quickly upfront, no doubt. But look at VI mitigation. VI mitigation didn’t have to be an additional component of post-closure analysis. Long-term stewardship, again, IC monitoring, that’s about it. Future liability, just a fraction, $75,000. Total project costs 1.9 mil.

So here’s what we did. Soil, source area soils excavated, you saw it wasn’t a very big dollar amount, wasn’t real big. It was a pretty small vadose zone. I should say unconsolidated vadose zone soil impacts. SVE system installed and operated for deeper vadose zone. In this case, it actually turned out to be a bedrock application, a sandstone, which was really intriguing. Engineers did a great job on that. Source area ground water treated with REGENESIS 3DME, CRS, and BDI again. This is a great combination for us. It works really well. Cut-off barrier, also, part of this remedy, barrier wall or a cut-off wall with PlumeStop installed immediately downgradient. And we do have plans to install the additional PlumeStop cut-off barriers downgradient. Downgradient vapor intrusion, pathway elimination, done. Anticipated LTS, again, IC monitoring for groundwater usage only.

Early results, here’s how it looks. Pre-remediation, in 2016, that red blob that you see there is anything over a part per a million, pretty significant compounds or pretty significant concentrations. Post-remediation, fall 2016, and again, this is only after the source area injection. So you can see that concentrations, you know, we’ve got an order of magnitude reduction in six months’ time. Post-remediation, spring, we’re still on the same order of magnitude but you can see that the extent is continuing to decline, I should say.

Here’s the way we’re hoping it all plays out from the life cycle. Remember, we’ve got a little bit more work to do on this one, but the analysis has proven true in other examples and we’re hoping it’s gonna be the same here. We have faith in the technologies. Total investigation in remediation, 3.8 mil. Cost of downgradient cut off barriers, 600K. Lifecycle cost savings due to groundwater treatment, $925,000.

So, you know, we’re talking about a 30-minute webinar here today but I don’t think we need to beat this any further, just three great examples. Long-term stewardship requirements are necessary. The associated cost to implement those LTS obligations are real cost analysis components, okay? Don’t forget to factor in the potential for future liabilities and risks from third parties. They are hard to quantify, but that doesn’t mean that they’re not real. You can save your clients some real money if they’ll only let you.

I mentioned this earlier but I think it merits mentioning again. Regulatory closure is only an interim step in the process of protecting our clients from risk, the people in our communities from exposure, and the environment from degradation. Thanks a lot. Let’s go to some questions.

Dane: All right, thank you very much, Jeff. That was great. That concludes the formal section of our presentation. And at this point, we would like to shift into the Q&A as Jeff said. So before we do this, just a couple of quick reminders. First, you will 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, after the webinar, you will receive a link to the recording as soon as it is available. All right, so let’s circle back to the questions here. Some good questions coming in, Jeff. A lot of…it looks like at least three folks have asked questions regarding future liability. On what basis were future liability costs calculated in your examples? I know you mentioned something about property value, is that right? There’s a lot of questions asking about details about that future liability.

Jeff: Sure, absolutely, guys. Great question. I fully anticipated that. Like I said, it really relies pretty heavily on the case-specific situations, and working with our attorneys, counselors and coming up with what we think makes sense. But I will tell you that very largely, it has to do with an estimated potential damage from a property damage claim. So, you know, there’s been analysis of court cases across different parts of the country. Depending on that analysis, we’ll see whether or not these types of claims are prevalent. And if they are, then we’re probably gonna sign a higher cost component to that.

At times, if it’s not a very volatile situation from that perspective, we might figure out how many different parcels we have, assign an average damage to that, and then maybe even take a component or a factor of that, be it 50%, 75%, 25%. It’s really hard, again, to quantify bodily injury claims. They come up every once in a while. They don’t come up all that often. And even when they do come up with these types of compounds, you know, their success in getting or demonstrating a real risk or a real damage just hasn’t really shown up in the case law.

Dane: Okay. All right, thank you very much. Let’s see here. So next question sounds like a good question. Overall, how receptive have your clients been to seriously calculating long-term stewardship costs?

Jeff: Well, you know, again, they’re very open to seriously considering it and evaluating it. As I mentioned earlier, we were in a bit of a unique scenario in that a lot of our clients actually have the benefit of historical insurance assets. We work very closely with the insurance companies. They are very open to this kind of analysis, and they really do appear to have a great idea and a great deal for the risks.

I will tell you, though, that most of our private clients will also really understand this. Because remember, I’m dealing with a lot of small business owners. These guys are, half the time, scared out of their wits, and they wanna do anything to help limit their long-term liability. A lot of times, they’re looking for an exit strategy. Dry cleaning isn’t as great as it used to be. It’s not as good as a market as it used to be. They’re looking for an exit strategy. I can’t tell you how many times people tell me, “I just don’t wanna leave a problem for my kids.” And so they’re very motivated to do whatever they can do, even if it’s their own money, to eliminate risk on the backend.

Dane: That’s interesting. Okay, all right. So let’s see here. Next question, several questions related to vapor intrusion. This one asks, “How might your cost saving analysis differ if VI isn’t a component to remedial action?”

Jeff: Well, I think that it’s a good question, which means that if you eliminate the vapor intrusion or the soil gas reservoir from those analyses, you know, long-term stewardships…I mean, from what I’ve seen, ICIAP guidance, the ITRC stuff that just came out, and then also from dealing with different state agencies, I’m seeing a lot of agencies want significant groundwater modeling…not modeling, pardon me, monitoring if you want to leave significant mass in place. It’s not just the IC monitoring. You know, if we’re lucky, we’ll be able to get them to agree on a limited monitoring well network, maybe some plume line stuff, maybe reduce to annual or even to five years. But the problem is if you’ve got significant groundwater impacts in place and you need to monitor them over the long haul, what’s the right number, 30 years? How long is 30 years of monitoring even if you do it in every 5 years? Those can turn into some significant dollars. You know, so when you start adding that up, it really becomes a significant component.

Dane: Okay, all right. So let’s see another…it looks like a possibly related question here. For your examples, were there soil gas conditions that required action? If so, how were soil gas conditions remediated or did soil gas naturally assimilate during groundwater remediation implementation?

Jeff: The second example that I showed where we actually had a significant sand soil gas reservoir, you know, that one did actually require evacuation through the SVE and that what was what we talked about. And again, the third example, we had significant SVE up in the source area where it was causing a problem. The first example, we actually had a finer grain material although the soil gas reservoir was there as an analysis component dissipated pretty quickly because groundwater table was pretty shallow and a lot of off-gassing straight into preferential pathways directly into basements. So that the soil gas reservoir itself was not voluminous, I’ll say.

Oh, real quick, though, Dane, the first part of that question was how did we address it. Anytime that there’s a vapor intrusion exposure identified, mitigation immediately to stop that exposure pathways is always the course of action.

Dane: Okay, great, yeah. And actually, that same person did ask a second part to that question which you just answered, which is was interim VI mitigation required, so thanks for noting that. Okay, so a few more questions here. A couple of questions regarding PlumeStop, which is great. The first one is how is compliance monitoring handled downgradient of a PlumeStop injection? And then also with PlumeStop injection, are VI concerns completely mitigated or is there still a VI concern? So if you might handle those couple of questions about PlumeStop.

Jeff: Sure, let me see if I can get those in my memory bank here. So the first one, how is compliance monitoring handled downgradient of a PlumeStop injection? From what we’ve seen so far, it hasn’t really changed. It’s not different from compliance monitoring from any other type of remedial action. You know, you will make your injection, it starts its process, and we start monitoring the plume downgradient of that injection point and watch concentrations decrease. Those concentrations are locked up in that product and do not cause concern for VI. So it eliminates it from the plume or from the…I’ll say from the dissolve phase, the mobile phase.

Dane: Okay. All right, so let’s see here, a couple more questions. We have…one here is, was your analysis based on NPV or total lifecycle cost?

Jeff: Those analyses do not include any present value components if we really are digging into the full-scale costs. In other words, you know, if we have to really sharpen our pencil and know exactly, and we are talking about long-term stewardship components that might be 30, 40, 50 years, we definitely will do a present value analysis of that. And we do that so it’s…but, you know, the thing is, though, if we’re able to seriously evaluate a remedial strategy that eliminates more mass upfront and we get to knock that 50, 40, 30-year timeframe down, you know, the present value analysis of that becomes less important.

Dane: All right. Okay, great. So another question here is regarding the institutional controls or IC, as you refer to them. Regarding the institutional controls for groundwater, are these generally related to a regulatory prohibition on use of groundwater for drinking water or were there aspects?

Jeff: The one that we commonly use, and as we see it in the Midwest anyway pretty frequently, is just a groundwater usage restriction, meaning no wells, no groundwater usage, period, for on-site groundwater. Now, that does vary from state to state. I think a lot of states don’t even really quite yet know what to make of it. And so the regulations are…or the requirements are a little fuzzy right now, but that’s what we use. We assume no wells.

Dane: All right. Let’s see here. Another question is, under what conditions are long-term stewardship only solutions the right solution?

Jeff: Well, I think that, you know, what is…how do you define right, I guess, but the deal is, like I said, the number one concern is eliminating risk. The number one concern is eliminating, I’ll say, exposure, pardon me. You know, if you got $12 and you spend that $12 to tell everybody to get out of the house, then that’s all you can do. You’ve eliminated the vapor intrusion exposure and you’ve taken care of that. You know, that doesn’t mean that the problem has gone away, but you use the resources that you’ve got to the best extent and to the best result possible.

Dane: Okay, great. Thank you very much, Jeff. That’s it. That concludes our presentation today. Before we sign off, just a few reminders. First, you will receive a follow-up email with a brief survey. We do appreciate your feedback so take a minute to let us know how we did. And you will also receive a link to the webinar recording as soon as it is available. And also, thank you for your questions today. If you would like more information about environmental engineering from EnviroForensics, please visit enviroforensics.com. And if you need immediate assistance with a remediation solution from REGENESIS, please visit regenesis.com to find your local technical representative and they will be happy to speak with you. Thanks again to our presenter, Mr. Jeff Carnahan, and thanks to everyone who could join us. Have a great day.

Jeff: Thanks, Dane. Thanks, everybody.