Hello and welcome everyone. My name is Dane Menke. I am the digital marketing manager here at Regenesis in Land Science. Before we get started, I have just a few administrative items to cover. Since we’re trying to keep this under an hour, today’s presentation will be conducted with the audience audio settings on mute. This will minimize unwanted background noise from the large number of participants joining us today. If the webinar or audio quality degrades, try refreshing your browser. If that does not fix the issue, 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 focus on a proven approach to reduce long-term risk on chlorinated solvent sites. With that, I’d like to introduce our presenters for today. We were pleased to have with us Joel Parker, Principal Engineer at Hamp Matthews & Associates, a firm that provides environmental consulting services to private and public sector clients located in the state of Michigan, but also with an expanding client base across the country. In his current role, he offers clients sound technical advice for optimal remediation outcomes and provides technical direction and guidance on environmental project strategy. Prior to joining Hemp Matthews and Associates, he served as the senior environmental engineer and remediation group manager at other environmental engineering firms.

We’re also pleased to have with us today Ryan Moore, senior technical manager and PFAS program manager at Regenesis. Ryan has 20 years of experience as an environmental project manager and laboratory account executive relating to multimedia contamination sites throughout the US. His experience has focused on site investigations of soil and groundwater contamination, corrective action evaluations, operation and maintenance of remediation systems, large soil removal remedial projects, and in situ groundwater and soil treatment. All right, so that concludes our introduction and now I will hand things over to Joel Parker to get us started.

Thank you, Dane. It’s a pleasure to be here and present this case study on a challenging former dry cleaner site where we are conducting in situ remediation in parallel with risk management at the receptor. And before I dive in, I’d like to just pay kudos to the team. And there’s a number of key collaborators on this project. First and foremost, our client, the State of Michigan Department of Environment, Great and Energy Eagle. They are the technical and financial lead on this project and I’ll touch on that in a moment. Regenesis, of course, provided the remediation compounds and the remediation contracting that I’m going to talk about as we move through this webinar. Beacon Environmental provided passive soil gas analysis that I think you will find very elucidating. And then GeoServe, a local drilling contractor that provided the bulk of the samples that you’ll see data from throughout the talk.

Last and not least, I’d like to just thank the HMA Internal Technical Team, the Volatilization Indoor Air Pathway Team, or BIAP Team, as they’re known, and you’re going to hear that acronym in the talk a couple places. Our internal data acquisition and data analysis and visualization teams were key to the data and the interpretation of data that you’ll see throughout the presentation. So in the vein of telling you what I’m going to tell you, I’ll quickly outline the talk. I’m going to just briefly intro the site. You can see you get a little preview of where it’s at here in Michigan. I’m going to touch on few key elements of the conceptual site model. I can’t go through the entire CSM, that talk, that would be an entirely longer and different talk and quite fascinating. I’m going to touch on a few interim response activities that we did in parallel with the RIFS work that we did to come to doing in situ remediation. Then I’m gonna get into the weeds a bit on what we did for in situ remediation, give you a current conditions update, talk about what the future looks like, and then close with some lessons learned.

So this site is in Temperance, Michigan, and here you see a aerial photo, the site proper, the subject property, is just less than an acre. It’s bounded by this red bold line. north is off on this photo and the site is located on kind of a prominent north-south thoroughfare in Temperance, Michigan known as Lewis Avenue and Temperance is kind of down here in the southeast corner of Michigan, Monroe County, almost to Ohio. Site was a dry cleaner from the late 60s until fairly recently and as I said it’s an eagle-led, it’s a state-led site and What that really means, one of the things that means is that the liable party is either no longer or just deemed financially incapable of leading the work at the site. So the state of Michigan EGLE leaves the work both technically and financially. There are plenty.

As I said, the site’s subject property, the former dry cleaner, just under an acre. And a new property owner acquired the property and has redeveloped it as a custom kitchen cabinetry shop. And through their due diligence process, in late 2018, they discovered PCE and related degradation CBOCs in a number of environmental matrices, including soil vapor, groundwater and soil. At that point, EGLE became involved and in early 2019, EGLE contracted Hemp Matthews and the immediate focus was on vapor mitigation at the receptor. As I said, this project is VIAF driven. It’s really related to the volatilization indoor air pathway. Here in Michigan, we use VIAF. For those of you in Michigan, you know, consider biop synonymous with vapor intrusion. So before I move on to the CFM, I want to orient you a little bit here.

I said Lewis Avenue runs north-south to the west. To the north, this is Eagle Ridge Trail, a street that we will talk about quite a bit to the north, and you see that this former dry cleaner is sandwiched into a lot of residential to the north. Fairly construction. This is a commercial property, Scoops Ice Cream, a really good ice cream shop if you’re ever in Temperance. And then to the south, we have another street and neighborhood, the Dempster Street, and this this neighborhood is a little bit older, but again what you’ve got here is a former dry cleaner kind of sandwiched in and amongst a bunch of residential development. Again, north is up, south is down. So now we’ll get into the CSM, touch on a few elements. As I said, it really is kind of a perfect storm of circumstances. Very shallow, unconfined sand aquifer. Fine, homogeneous brown sand overlying a clay aquitard, typically around seven feet below grade is the aquatard. Groundwater is extremely shallow here, typically encountered three to four feet below grade. And here you see a plan view map of the site with groundwater potentiometric surface contours overlaying and you see flow arrows to the north and flow arrows to the south.

So groundwater flow is bifurcated, there is a divide. The local surface water that should control shallow groundwater flow is to the north, even further north than Eagle Ridge Trail. So flow to the north was not a total surprise. Flow to the south was a little bit of a surprise. What we found as we immediately got into this project is that these basement, because of shallow groundwater basement sump systems were running nearly continuously and acting as hydraulic sinks and you can kind of see that you see the concentric circles around this home along Eagle Ridge Trail and then you see this very sharp steep hydraulic gradient are coming to this home along Dempster. Another distinction I want to make is that these homes with the green A’s or These structures with green A’s represent structures that we assessed via, and then these structures with the yellow coloring and the M’s were structures that indeed had shallow groundwater and soil vapor intrusion, and we had to mitigate these structures.

So again, I said that the initial focus was at the receptor. let’s get the receptor. We came into a situation, receptor is being exposed with indoor air, let’s get the receptor protected, which we did via retrofitting subslab depressurization systems into both structures. And ultimately, we were able to prove that as a successful means of risk management through indoor air samples in the structure. However, and this is a picture of the Dempster home. You can kind of see the map here of that home. And then this picture to the right just kind of conveys the type of shallow groundwater episodic challenges that we would periodically face. In other words, it’s really tough to depressurize the full footprint of a structure when you’re faced with a water table at this elevation. So this kind of launched us into asking some questions of ourselves could we potentially remediate vapor source in parallel with protecting the receptor through the SSDS type system.

So again, this is a exposure pathway driven project, VIAP is the Exposure Pathway Volatilization indoor air. And throughout the talk, and you’re going to hear me talk about CSM refinement, and we’re going to present data. And I want to stress that it’s very focused on source-transport receptor relationships. So this STR linkage or relationship, and this graphic, you’re going to see this again later in the talk with some data, this exemplifies that focus. To the left here on the graphic, you see the former dry cleaner and what I’ll call the source, kind of generically, albeit I’m kind of tipping my hand and showing one of the sources that we discovered through CSM refinement, a solvent drum. So we’ve got this gross punitive source at the former dry cleaner. Then we’ve got this transport mechanism, bulk advective groundwater flow, and then we’ve got our receptor who is being potentially exposed by a water and vapor intrusion through their basement zone.

So the point of this slide really is to just emphasize this focus on source transport receptor relationships, and it kind of set the stage for some later graphics. So, as I said, we did a lot of CSM refinement. It was very iterative, and we used a variety of techniques, including ground penetrating radar, coincident groundwater and saturated soil sampling, soil traditional soil gas sampling, again, really focused on source transport receptor relationships, and then we also through Beacon Environmental Services, we did this passive soil gas survey and that’s what this map that you see here to the right, I’ll call it a heat map of PCE in the soil gas. And so just to kind of orient you again, here’s the dry cleaner, north is up, here’s the home that we mitigated to the north, and then the home that we mitigated to the south is almost off, just off the map here. If you look over at the scale, just crudely, blue is cold, orange is warm, and red is very hot.

This passive soil gas sampling involves the installation of these devices, letting them sit for a few weeks in the subsurface, and then retrieve those, send those to Beacon, they analyze them and give you the results back, and also give you a map like this. And so this really, to us, elucidated several things. It got us focusing on this area just to the south where we were kind of yellowish-orange. Well, this ended up being a spent solvent tank that was a direct source to the home to the south. It also got us focusing to the east the former dry cleaner in the backyard of this residential property. This ended up being some commercial septic tanks formerly related to the dry cleaner. And maybe most importantly, it got us focused on this kind of north-south orientation of this reddish-orange hotline, which was synonymous with a 12-inch storm sewer that ended up being a preferential pathway for transport so To the north the plume really wasn’t moving with bulk of active groundwater flow It was moving along this 12 inch storm sewer, which was installed around the year 2000 significantly after this contamination would have been released So we thought this was a really cool technique to help refine the CSF And then I’ll quickly roll through just some pictures of some other techniques.

Here we are in the backyard of the Dempster home doing just ground penetrating radar. You can kind of see these rectangular lines on the ground. That’s us discovering this former residential septic tank that was still connected to a of the home and also had a large drain field that later acted as a, that we later discovered acted as a secondary source. Here we are using the same techniques in the backyard of the Eagle Ridge Trail Home. We’re kind of down here where these red tanks are and we’re, this is our first discovery of these red tanks one and two that ended up being large commercial septic tanks formerly connected to the dry cleaner now on residential property and ended up being pretty significant sources of contamination. So I’m going to just touch on some, quickly touch on some interim measures before we get more into the in situ remediation part.

Again, I mentioned here’s the former dry cleaner. Here we are where that spent solvent, where that heat map was for the beacon. We ended up doing work there, targeting our RIFS, and lo and behold, we discovered a spent solvent tank. Was really just a 55-gallon drum laid on its side. It was found in a very dilapidated condition. We ended up hand-digging, hand-exposing, removing all the sludge, and removing some grossly impacted soils related to this. This, because of its proximity to the structure, it was all hand excavation with some removal via basically a vacuum air knife-type equipment. This soil was very grossly contaminated, greater than 1 million parts per billion, all of it characteristically hazardous. We ended up getting about 8 to 10 cubic yards out of here, and the coolest thing about it that we were able to backfill this area knowing that there was still a lot of residual contamination around the perimeter here.

We were able to backfill this area with P stone and some remediation in some potential future remediation delivery infrastructure, which you see us doing here. Also, I mentioned the commercial septic tanks. Here you see tanks one and two they would be right here on the map and there’s the back of the former dry cleaner so here these are in the backyard of somebody’s residence and these were previously unknown by all parties these were massive concrete vaults approximately 15 feet below grade and ultimately they contained about 30% By volume, this sludge that you see me sampling, and this sludge was very characteristically hazardous to the point that its disposal, only disposal option was to be placed in drums and incinerated, which is what occurred.

We ultimately basically abandoned these tanks in place after emptying them and cleaning them. Then also, I mentioned the, this, now we’re back to the Dempster property, and I mentioned that we found this residential septic tank, well, there was a, we also found a pipe that ran from that tank south and was still in connection with the basement wall, and here see, if you can see my pointer, my cursor, there is the pipe, still connected, stubbed off at the basement wall. And we actually were able to deduce that this pipe was also intruding CVOCs into the indoor airspace and ultimately we were able to cut and cap and abandoned that pipe, which caused a dramatic improvement in indoor air quality in the basement, particularly with regard to CIS-12DCE.

So now I’m gonna get into the data to kind of set the table for in situ remediation. You know, in parallel with a lot of that work that you just saw pictorially, we did a traditional RIFS. This was all, the bulk of that was done in early 2020, right as COVID was hitting. And this RIFS was also done around that same time. And we did a number of soil moorings, almost 100 saturated soil samples, almost 40 groundwater samples, really examined coincidence soil water ratios to help us understand was an area a source? Was it more of a distal plume or mid-plume area, or was it very near the receptor? Looking at, again, coincident soil-water ratios. At the end of the day, we ended up with a contaminant distribution in saturated soil that kind of looks like this amoebic Loch Ness monster. In fact, we came to refer to this as Nessie. You see a plume from that spent solvent tank kind of directly heading right for the basement sump crack of the Dempster home. You see a plume coming from the septic tank area in the backyard here traveling down the storm sewer over to the Eagle Ridge Trail home. And then also there was some, because of that bifurcation and flow divide, you saw a plume kind of heading from this septic tank area still heading toward the Dempster basement sub-croc system.

This areal extent is about 0.4, not quite half an acre, and in total it had about 105 kilograms of total mass, the bulk of which was PCE. In groundwater, a very similar picture, a little bit more cysts in the groundwater than in the saturated soil, vinyl chloride in the groundwater, even some dissolved ethane, albeit low concentrations, about 20 microgram per liter at a few key locations in the groundwater, but generally, the same basic contaminant distribution, which really didn’t come as too much of a surprise. So as we started to go through the RIFS, we noticed that one, redox was already pretty favorable for reducing technologies. Again, acknowledging that groundwater’s pretty shallow, so it’s easy to access or deliver to the groundwater. and we started to ask ourselves, could we reduce the source mass significant, could we, could we do in situ remediation to reduce source mass, you know, significantly and achieve low VIAP screening levels in groundwater at the receptor and these are quite low screening levels, almost basically method detection limits for these chlorinated compounds.

So as part of the RIFS, we embedded a number of technologies. And this is the preliminary screening matrix from the RIFS report. Right away, due to logistic constraints, the cost of hazardous waste disposal, and just the intrusiveness, a number of kind of brute force ex situ and even in situ technologies were just deemed infeasible. their cost was just getting too high, too intrusive on these two residential properties. We knew that the redox was already looking favorable from a reducing standpoint. And with the remedial clean-up objectives of qualitative, reduce source mass, and then quantitative, achieve low VIAF screening levels at the receptor, we retained some in-situ technologies, primarily in-situ chemical technologies, both chemical reduction and chemical oxidation, and in-situ biological technology, namely halo respiration or what a lot of people call enhanced reductive de-coronation.

We also retained an in-situ physical technology that we envisioned coupling with those destructive technologies, colloidal activated carbon, with the mindset that those destructive technologies coupled with carbon could give us very rapid expeditious lowering of concentrations and achievement of the RCOs, and yet coupled with destructive mechanism, we could get this long-term sustainable treatment train. So after a vetting process and a bid process, we selected regensis to provide both the remediation compounds and the on-site delivery, and so I just want to talk about our treatment train for a minute. we selected in situ chemical reduction, coupled with enhanced reductive dechlorination. And at some locations of the site, we wanted to go further and yet couple that or fuse that with the colloidal carbon, what I just talked about on the previous slide. And at the risk of being redundant, I’ll kind of hammer on that a little bit more on this slide.

So for the ISCR, we selected the sulfidated micro ZVI, sulfonated zero-valent iron to promote aviotic degradation. For the biological component, we selected, in some areas, hydrogen release compound or in other areas, 3D ME as the electron donors. And then in all cases, the halo-respiring inoculum of BDI+. So this concoction or this accoutrement would offer us an electron donor and the halo-respiring bacteria needed to promote microbially-mediated transformation of these chlorinated ethenes. And then lastly, but importantly, at some locations, and we’re going to touch on those, we combine those two destructive technologies with rapid physical absorption via plume stop. Again, with the hypothesis that coupling the destructive technologies with this adsorptive technology, the porosites would remain open for continued long-term sustained treatment. So we would get both rapid treatment and sustained long-term treatment.

Here below, we show a couple of the destructive pathways at play. This upper pathway is the microbially mediated sequential decoronation where PCE would de-coronate and go through TCE, cis-1 ,2-DCE, vinyl chloride, and then non-toxic ethyl. The lower destructive pathway is the abiotic pathway, and that is where we see a number of acetylenes formed, eventually acetylene, which would then be also converted to ethyl long-term. So with all that, with that hypothesis or concept for treatment train in mind, we set about breaking this Loch Ness monster up into parts and based on coincident soil-water ratios and where we thought we could get the most bang for the buck, we broke the site up into six areas, areas one through six that you see here on the map, and areas one where the spent solvent tank was, area two just down gradient of the septic tanks, and area four encompassing tank one, the tank one area. Those were considered to be sources and the deployment there was a little bit more of Well, let me back up and say that delivery was accomplished at all locations via direct push geo probe.

At areas one, two, and four, the deployment was a little bit more of a source grid style, touch the whole thing up, touch it all. Areas three, five, and six, especially these long, kind of skinny ones, three and five, were really more distal PRB style configurations. Areas two and four did not have colloidal carbon or plume stop. And that was primarily because they were at locations where the hydrodynamics were quite slow. If you recall, they were kind of in that flow in the area of the flow divide. And so the hydraulic gradient, some of the other hydrodynamics here were a little slower and we felt we could get away without the plume stop here. Whereas areas one, three, six, and five really on severe flow paths to the receptor, we wanted that instant gratification that came with the absorption that the plume stop could provide. Here at the lower left, you see the recipes for all the areas in total 121 injection points, just under 11 ,000 gallons of injectant volume.

This is really the same information, and I kind of already explained this, but areas one, two, and four were sources. Areas three, five, and six represented a little more distal plume, and so the FAST dynamics at one, three, five, and six necessitated that we added plume stop to the injectant mix, whereas this slower dynamics at two and four allowed us to not use PlumeStop. In this lower table here you just see some of the some more of the rationale and thinking that went into our initial pilot. And I’m going to roll through a few pictures somewhat quickly here, but here is area five. There’s the former dry cleaner. Here we are at the Eagle Ridge Trail and this is that area five along that storm sewer flow path up to the receptor. And you see a number of hoses carrying injectant from a remediation trailer that’s kind of around the corner behind these trees to injection points.

Here are those injection points. Here’s one, here’s another one with the red hose. It’s simply a GEOPRO broad with a tight, you know, leak proof fitting, injecting from an injection trailer under a slight amount of pressure through the GEOPRO broads. Here we are at Area 1. This is the spent solvent drum location, and here you see this is the concrete. Remember our excavation, we replaced that concrete. That’s right in here. So you see us here’s a geo probe rod geo probe rod. Here we are. Remember that PVC Delivery gallery that we installed here. You see us connected to that and another rod So that’s kind of what that’s what injection looks like an area once here is a close-up of that and the cool thing about this is you see one of the field people was dropping a baler down a proximal well and And here is visual identification that the material is indeed being delivered and distributing. This black color comes from the plume stop and I believe the sulfated micro ZVI also has a black color, but this is definitely got plume stop in it.

And then here is the remediation trailer. This remediation trailer is parked at the southeast corner for the duration of the injection projects, so we were able to inject in areas one through six with just the the trailer parked right here at the southeast corner of the former drag clear. So now let’s just look at how we did, and this was some really early performance data, and this actually is data pre-remediation. And again, from left to right, this is distance from the source, from the spent solvent tank, like this MW-20 and MW-19, these are those wells that you saw, one of these is that well that you saw with the guy pulling the baler out that was black, so you see, pre-remediation, we had PCE up around 78 ,000 micrograms per liter, and then you see the concentrations with distance, of course, degrade, or decline, I should say, not degrade, but decline, reduced concentrations as you get closer to the receptor, albeit still a few parts per billion in the sump water at the receptor. And then cysts, you know, not a lot of cysts, a little bit more as you get further away from the receptor.

Now let’s look, after one month we injected, we delivered in August, so the black line is right before injection, now this red line is one month after delivery. and we see some decline already in PCE, little bit of increase at MW32, which happened to be in that drain field of the connected to the residential septic tank. And I mentioned before that ended up being a secondary source and we see a little bit of cysts, but we’re only, we’re early at this point, only one month out, two months out. We still see really nice rapid decline in PCE and we’re seeing some cis generation to be expected, right, because we’re dechlorinating, and then three months out fairly similar but very encouraging results. So we saw a really rapid decline in the source in PCE, a little bit of a bump in PCE in this former drain field area, which we considered a second source based on soil water ratios.

Mind you, we didn’t deliver in that area for the first pilot. You know, and we see some bumps and sifts which are better to be expected. We felt very encouraging results after only three months. So then about six months later, with comparable results still occurring, we decided to augment the pilot. The first pilot we did in August of 2020 and this augmentation or what we call phase two we did in May of 21 and We added four areas area seven which now really connects two and four together and encompasses the bulk of the former commercial septic tank area area eight which now encompasses this drain field this former drain field that we started to field was really a secondary source. And then we augmented a bit in area one where we were still seeing some residual cyst buildup. And again, the main objective here was to give us some better spatial coverage, although we did increase our bottom injection depth to eight feet from seven feet before wanting to get into that upper six inches to a foot of the underlying clay.

So now I wanna fast forward to current conditions or what we perceive to be current conditions. This is June, 2022 data. So this is approximately one year after that augmentation event. And again, this is that source transport receptor flow path from the spent solvent tank from the former dry cleaner to the Dempster Street Receptor, the basement cell. And we thought this was a really clever way, an interesting way to present this data. Here you see the cross section of the flow path. The blue shows you the areas where we did in situ injections. And then down below, you see trendline graphs for PCE and cis-DCE for the source along the transport route and at the receptor. And then what we’ve done here in this upper right, it’s a lot of information, so hang with me, folks. I realize that. But what we’ve done also is listed the maximum concentrations that have ever been seen, and then what the current concentration is, okay?

So, here in the source, we really don’t have any PCE, and actually along this whole flow path, we really have no PCE being detected anymore. We still have a little bit of DCE, but considerably less. You see it initially blipped, and it’s hard with the scale, I know, but it’s pretty darn low now at the source. And as you get closer to the receptor, it’s even lower. And as you get to the receptor now, we’re non-detect at the compliance point, which is this basement cell. And we’ve achieved that now for about six months, so we’re pretty excited about it. An analogous figure for the north plume, this is the plume that flows along the storm sewer. Here you see the storm sewer. Here you see the tank one with the sludge. Again, keep in mind that we removed all that, but it spilled over and caused a lot of residual source contamination. And you see fairly similar results.

That is, I want to mention that this vertical line represents the phase two pilot augmentation. So the first pilot started right around here, just after the first monitoring point. And then here’s the pilot augmentation. So again, pretty similar results. Really good destruction of PCE. Again, not a lot of PCE in the transport anymore. And at the receptor, no PCE. In fact, we’re non-detect, again, for PCE at the compliance point, which is the basement sump crack. Similarly, we had, as the other flow path, We had some big spikes in SysDCE, but that started to come back down. And at the receptor, again, importantly, we are achieving the VIEP screening level for DCE. We’ve got a little small detection, 1.5 micrograms per liter, and that’s been pretty consistent too over the last six months. So we’re really excited about this data from the standpoint of achieving these stringent biop screening levels at the receptor.

So another more familiar way to look at this data is to look at the change in groundwater concentration over time in a plan view. So here was our Loch Ness Monster for PCE and groundwater pre-remediation. See the hotspots. You see the fact that it’s traveling along the storm sewer to the receptor or not with bulk and back to groundwater flow. Here’s where it was about eight months after the first pilot, right before we augmented. And you can see a significant contraction of aerial extent and severity of the PCE plume. But again, we wanted to hit this area in particular with some more spatial coverage in this area with some spatial coverage and then after the augmentation the current conditions june 2022 here we see out of 20 some monitoring points we’re left with one tiny little blip that’s above 10 micrograms per liter so just dramatic reduction in aerial extent and severity of the PCE pool. This actually calculates to a 99.9% reduction in the groundwater mass.

If that reduction were to hold up in the saturated soil, that would mean that the remaining soil mass of PCE is about a tenth of a kilogram. So that would represent almost a hundred kilogram reduction in PCE mass. Let’s do the same thing for cis-12DCE because that’s a pretty prominent contaminant out here as well. Again, here’s the pre-remediation Loch Ness Monster. It’s got a little bit weirder shape, we came to learn. But again, about the same, about four of an acre of aerial extent, some hotspots. This is pre-remediation for CIFS-12DCE. After eight months, well, it’s actually gotten a little bit bigger and more severe, right? There’s a couple of red hotspots that are above 10 ,000 and it’s gone up in total mass. If you take this area and convert that to a volume and convert that to gallons of water, we’ve actually, we’ve gone up in mass after eight months, you know, to be expected to a degree because we are de-coronating here, but how are we doing now?

Okay, after our phase two in May of 21, a year later, we’ve seen significant aerial contraction and a decrease in the magnitude and severity of the CYS-12DCE plume. This represents overall about a 63% reduction in groundwater mass from the pre-remediation condition. And again, if you translate this into saturated soil mass, there’s about two and a half kilograms of CYS left from about six kilos before. So again, pretty significant reduction. we think it’s really very promising after only 12 months of doing the phase two augmentation of the pilot. So what does the future look like? We acknowledge that, you know, groundwater moves slow and things take time and one or two quarters do not a trend make. So we’re going to stay watchful. And that means we’re going to continue to monitor on a quarterly basis. We’re going to monitor groundwater and soil gas at probably about 20 to 25 locations throughout that that point for acreish former Loch Ness monster plume. So we’ll continue to look for BOCs and dissolved gases and other performance indicator parameters throughout that to to really develop multiple lines of evidence to give us the warm fuzzy that this is really working outstandingly well.

Again, we’ll monitor quarterly a nice spatial network. We’re going to keep our eye out for diffusion from the underlying clay. We realize that that could be a possibility. One of our plans is to, after what we hope is about a year of stable, consistent groundwater data, we would like to go out and collect saturated soil at key locations to corroborate this mass destruction and really verify, have we really remediated this much off the saturated solids. To close out, here’s a nice picture of area five where we were doing all those injections in the beginning of the remediation part of the presentation. To close out, you know, we acknowledge that mitigation at the receptor can be really challenging due to some factors beyond our control. You know, really shallow water table can really provide some challenges.

When you’re considering in situ remediation, we think saturated soil data is really key for not only predicting the mass to be degraded, but understanding the balance between remediation compound and contaminant mass. we also Institute vapor source remediation can be effective in parallel with mitigation at the receptor and Lastly that these low Detection level type screening levels can be achieved at compliance points as a Remedial cleanup objective and with that I would like to turn it over to Ryan more Yeah, thank you Joel. Um, I the information is a very good case study and we look forward to seeing what the future brings on the project.

You know my name is Ryan Moore I’m the senior technical manager for our Great Lakes District and also our PFAS program manager. I’m just real quickly going to kind of talk about some of the technologies that Joel mentioned that were used there at the project site. First before I get in that just a quick introduction of Regenesis for those you may not be as familiar with us. You know we’re kind of broken up into four main divisions. Our research and development team is headquartered down in Southern California and our headquarters in San Clemente, California. Our remediation technologies, that’s the actual products that are used to be injected at project sites. You know, anything from enhanced aerobic, anaerobic, bio, a couple different in-situ chemical oxidation technologies, ISCR, in-situ chemical reduction, and then in-situ absorption and biodegradation. We also have our field services, we call that Regenesis Remediation Services, where we have crews and trailers strategically placed throughout the country to actually go out and do the applications, as you saw here in Joel’s presentation. And then finally, we do have land science technologies, which is a premier vapor intrusion barrier technologies where we go out and put down those barriers, you know, prior to constructing new buildings.

Real quick, you know, Regenesis, we really kind of run the full spectrum of the types of project sites anywhere from the corner dry cleaner or corner gas station all the way to large industrial manufacturing or Department of Defense projects. Again, the contaminants, you know, I think majority of what we’re doing these days is chlorinated solvents, petroleum hydrocarbons, and things like PFAS. But we get into a lot of other organic contaminant treatment. So our process, and this is really what was key with working with Joel on this site, you know, we spent a lot of time on the front end listening to what Joel had to say regarding the site goals. So that site evaluation process, before we even get to the technology selection, is real important. And if we don’t listen to the concern that Joel has, and it could be, hey, you know, we’ve got the shallow groundwater, you know, we can’t, you know, be having any negative impacts on those receptors that are really close to the treatment. You know, it could be timing goals as well. You know, this is a project where there was true risk, true vapors, you know, initially going into these buildings.

And so what Hant Matthews had to do is kind of, you know, mitigate that and stop that risk right away. And then looking at the groundwater treatment, you know, how do we, you know, you know, have sustained reductions over time? So understanding Joel’s goals and listening to what they needed helped us kind of come up with this strategy of utilizing the plume stop and the S micro ZVI. When we get done with the kind of the technology selection, well, we’ll put the design to get together. That’s in true collaboration with Hank Matthews and other clients when working with them. You know, so there’s a lot of upfront work before we ever get out to product implementation. When we get out in the field, obviously the trailer, you know, you saw the pictures of our guys and the trailers out there doing the work, you know, nobody has more experience with the application of our technologies than our own guys. And so this is something that they do every day.

So product implementation is an important step that you really don’t want to miss out on because all the chemistry is great in the lab or in theory, but if you don’t get it where it needs to go, you’re gonna show non-performance. And that’s something that we really don’t have an appetite for. And then finally on the back end, when you start getting data for your project sites, we really spend a lot of time with clients to kind of go over that from a post op evaluation, right? You know, how is this looking? How does it compare to similar sites? Am I ahead of schedule or behind schedule, et cetera?

So real quick, you know, the three primary technologies that were talked about today, PlumeStop, S-micro, ZVI, and 3D micro emulsion. So first, you know, PlumeStop. What is PlumeStop? In essence, it’s activated carbon milled down to really small particles, one to two microns. It’s the size of red blood cells, right? As you can see in the video here, it really is easily mixed into a water solution that makes it easily injected, right? When we inject it under low pressure, it allows it to get even distribution in the subsurface. In essence, what we’re trying to do is convert that aquifer into a purifying filter. The goal of the plume stop treatment is really, again, coat the contaminant flux zones and then control against long-term back diffusion. Here in the picture, you see, this is not from Joel’s site, but an example of what a good soil core would look like post-application with Plumestop. You see that real good uniform distribution of the colloidal activated carbon.

Next, real quickly, 3D micromulsion. 3D micromulsion is our electron donor. Again, Joel talked about the different processes or mechanisms for remediation here, and the primary one is reductive chlorination. Again, like Joel said, converting PCE to ethene is the goal. Well, enhanced reductive chlorination has been going on for 20-plus years. A lot of times, and especially in the early days, what people really used was soluble substrates or simple sugars. It’s really an inappropriate substrate to use, primarily because it would release hydrogen very quickly and kind of wash out. Typically, after four or six weeks, you’d have to reapply. So theoretically, in most cases, for simple sugars like this, you’d be reapplying six or eight times a year. Well, in the late 90s, Regenesis developed an engineered controlled release substrate, or we called it HRC, hydrogen release compound. And hydrogen release compound is still used to this day, and a lot of times it’s used with our Plum Stop product because it won’t interfere with the desorption of the carbon. The benefit of hydrogen release compound was that you get greater than two years of longevity in terms of the hydrogen production, and you avoid that multiple applications. Regenesis kind of looked at this and said, well, how can we improve that even further? And that’s how we got 3D micromulsion.

In essence, what we did was taken that HRC molecule, which is that lactate and polylactate esters, and combined it with a long chain fatty acid. So now with 3D micromulsion, that long chain fatty acid, in essence, it helps it distribute a little bit better. so you’ve kind of got a hydrophobic and a hydrophilic ends, it allows it to distribute very evenly in the subsurface and kind of self-distribute a little bit on its own. But the primary benefit of the 3D Micromulsion is having that long-term hydrogen production of up to five years. So with a one-time treatment, we’re gonna get fast release of hydrogen, mid-release of hydrogen, and then long-term release of hydrogen. So for example, for like Joel’s site where the 3D micromulsion was used, we’re gonna get treatment many years after initial application. Onto the S-micro-ZVI, right? So what is ZVI? It’s zero-valent iron. It’s just nothing more than an engineered reductant that is manufactured to be reactive with chlorinated solvents and water. Why do you use it, right?

One, you can address the CVOCs through the reductive dechlorination process or a chemical reduction. And when doing the chemical reduction, it can help reduce daughter generation. Kind of back to the graphic again, that Joel showed is, you know, this pathway, the top pathway again, is that reductive dechlorination process that we’re using a lot of times in the bioprojects, but the abiotic pathway or beta elimination pathway, it’s often called. So, the parent compounds of PCE and TCE will convert to different acetylenes and then through to ethene and ethane. Now you don’t, you know, you don’t, sometimes people think you’ll never generate daughters with using iron. It’s not true. In a lot of cases, iron will react a lot with water, so you still get this kind of traditional reduction pathway where DCE and vinyl chloride will be generated. The goal, though, is to minimize the generation of daughters through the abiotic or that beta elimination pathway.

So a couple of quick slides on the difference of S-micro-ZVI and commodity ZVI’s. First, bare metal iron will react mostly with water. And on the right, you see a graph here in the white column is the reactions of bare metal, the bare ZVI. You get almost 90% reaction with the water and a small maybe 10 or 15% reactions with the TCE. Well, what does that mean in terms of your project? Well, first, it’s going to kind of create this passivization of the iron particles. In essence, think of it as kind of like a rind or a rust forming around that iron particle. It’s going to decrease the efficiency of the electron’s transfer. and so you get less treatment or you know you’re not using the iron to its full potential. Our solution is to coat that iron particle with an iron sulfide and when you give that coating or that sulfidated coating you’ve kind of reversed that relationship in terms of reactions with water right instead of now reacting mostly with the water it reacts very little with the water and mostly with the parent compound.

So again, back to the graph on the right, you see that that bar represents that you’re getting more 90% plus, you know, reactions with the TCE and very little with the water. So, you know, by coating the iron particle with this iron sulfide, we minimize reaction rate with the water and we maximize the reaction rate with the CVOC. Next, I want to kind of show example or kind of a few slides here that really visually show you the difference between commodity powdered iron and the colloidal S-micro ZVI, right? So what you’ll see is that first when adding iron, this is the commodity kind of powdered iron, it’s kind of clumpy. You add it to water. This doesn’t mix very easily. You can shake this up. You can stir this. Think about trying to inject It’s not going to go in very easily. One, the iron particles are very large. You won’t get uniform distribution. And it’ll clump and kind of settle out.

So you have to have lots of agitation. When you look at the S-micro-ZVI, again, it goes in kind of like a liquid. And when you just stir it, the iron particles are so small that it is easily injected in the subsurface. And it is great with injecting under low pressure. You can see even after a few minutes, the iron in the S-microZVI will stay suspended in the water much longer than a commodity powdered iron. So you not only get the benefit of the reaction efficiencies with the S-microZVI, but you also get the benefit of the ease of use or the injectability. You know, real quick before I end it, these technologies, there’s a lot of synergy with the S-Micro ZVI for our existing products, like with Plum Stop or with 3D Micromulsion. As the example from Joel’s presentation, Plum Stop and S-Micro ZVI, they’re mixed in the same tank and blended and injected all together. So that makes it from an application and ease of use, very application friendly, so to speak. And then with the 3D Micromulsion and S-Micro ZVI, again, they could be mixed together and applied at the same time.

By combining these different mechanisms for mediation, you get much more efficient treatment, you get kind of that acceleration on the timetable, especially when you’re using the plume stop, and your daughter product generation is lower. And so it’s not that you won’t generate daughters, but instead of getting these large peaks post application, you’ve really muted the daughter generation. And so that helps to get results kind of back to what Joel’s site looked like. So with that, you know, again, I appreciate the time and we thank you, Joel, for your presentation. It’s very informative and we look forward to hearing your questions and talking with you guys.