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Using Geology to Follow the Groundwater: Follow the Flow to Successful Remediation

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Video Transcitption

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 the 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. The topic of today’s webinar will be environmental sequence stratigraphy. To give us insight into this topic, we’re pleased to have with us today Rick Cramer, ESS Practice Lead at Burns & McDonnell. Rick is a California Licensed Professional Geologist with over 30 years of environmental experience and serves out of their Brea, California office.

Rick has a bachelor’s of science degree in geology from the University of the Pacific, and a master’s of science degree in geology from the University of California, Davis. He began his professional career in the petroleum industry and pioneered the application of sequence stratigraphy to groundwater projects. We also have with us today Craig Sandefur, Vice President of Remediation Applications Development at REGENESIS.

Craig Sandefur has more than 20 years of experience in the remediation industry and has developed much of the current product application capabilities at REGENESIS. Mr. Sandefur was the focal point in the development of what are now commonly accepted direct push application protocols for delivery of electron acceptors like ORC Advanced, electron donors like HRC and 3D microemulsion, and chemical oxidants like RegenOx. Mr. Sandefur has successfully designed and implemented a wide range of in-situ remediation strategies on hundreds of projects and provides expertise in the areas of technical troubleshooting and field performance.

All right, that concludes our introductions. So now I’ll hand things over to Rick Cramer to get started.

Rick: Thank you, Dane, and thank you all for your attention. So the overall thesis and approach, and what I’m gonna be talking about today is really about what I consider a paradigm shift in our industry, environmental industry, and more of a focus on geology. And a subset of that is environmental sequence stratigraphy. By that I mean this is focusing on sedimentary aquifers.

So generally in any sites that are underlain by sands, silts, and clays. So that’s just a general background. That’s the focus, and as Dane mentioned, I’m a Practice Lead for our environmental sequence stratigraphy practice. But all the work that you’re gonna see here is primarily done by our lead stratigraphers, and that’s Mike Shultz whose out of our office in Concord, and Colin Plank whose out of our Grand Rapids office.

So this is an outline of what I’ll present. First I’ll focus on geology, then why environmental sequence stratigraphy, and then what is ESS. And then the main thing is to get to the case studies to show the application. So I’m starting off with a definition of geology, the science that deals with the earth’s physical structure and subsurface, its history and the processes the processes that happen on it. And my focus here is about the science of geology, and that’s more than a boring log. It’s more than just looking at individual data that we collect.

It’s really about applying the science to interpret between and beyond where our data are. And that’s where this application of sequence stratigraphy comes in, and it’s primarily like I’ll show you in a little bit, it’s primarily about the practitioner, the trained stratigraphers. And the reason this is important for our groundwater projects is that the geology really is what defines the subsurface plumbing because it’s dark down there. We have only limited amount of data to try and understand what’s the uncertainty of the subsurface.

And before I go too far into some of the details and bury the headlines, I just wanna show the takeaways from our case studies real quick and that’s, again, about this focus on the geology. You know, and the first that I’m gonna show from Silicon Valley on the left, what you see is the original conceptual site model, which did not focus on understanding depositional environments which we’re gonna talk about, and the geology impact or control on pathways. On the right, you’ll see the geology-based CSM which actually maps out the preferred pathways in the subsurface.

And that was key for defining the sources from comingled plumes. And the second that I’ll show is on the top you see before are ESS analysis that just was a lot of lumping of understanding of the subsurface, whereas after ESS we’re able to define the details of, in this case, channel deposits which helped to save, like, over $50million in the remediation product design.

So why ESS? I just gave a couple of reasons right there, but it’s about building an improved more representative subsurface conceptual site management about understanding the plumbing, and about better outcomes. And the main reason this ends up showing up in our projects, it really reduces because we’re able to reduce this unnecessary treatment of clean, unimpacted water because we’re able to better understand the contaminant migration pathways. And target the contaminated mass more effectively.

Now, this is a paper that came out, a report that came out in 2013 from the National Research Council. And these were some of the results from that paper. And it really puts a spotlight on the importance of understanding the geology and the heterogeneity. This report said there are more than 126,000 sites, contaminant groundwater sites, in the U.S. that require remediation. And more than 10% of these, over 12,000, would be considered complex, which generally is saying that we’re not gonna be able to clean these to established endpoints due to the inherent geologic complexities.

So right there, that puts a focus at, yeah, yes we have been successful, there’s a lot of sites we’ve been able to take care of over the last 30 years. But those remaining complex sites are still an issue, and it primarily has to do with the complexity of the subsurface. And that focus evolved in a collaboration with EPA, so Mike Shultz and Colin Plank and I are coauthors with Herb Levine from EPA Region 9 on this EPA technical issue paper, on ESS as a best practice for site management. And oh, another one of our coauthors is Ken Earman.

So that’s another outcome of this, again, focus on geology. But now I’m gonna talk about what our roots are in order for us to understand where we are now and how we look at the subsurface. You know, like any culture that’s developed, you need to look at where it evolved from. Our industry evolved out of engineering, from engineering firms primarily, and also on the hydrogeology side from groundwater productions side. So that shows by the way we…the standard for defining the subsurface, describing it, is the unified soil classification system, which is an engineering practice.

It defines the geotechnical and the soil properties and does not focus on the geology itself. And then like I mentioned, on the hydrogeology side, we evolved from our water supply industry, which we’re talking about a whole different scale there. And that’s where these assumptions of homogeneous and isotropic conditions, they’re reasonable assumptions to make. And that’s also the case, probably, for thousands of those sites from that study, but when we’re talking about the remaining complex sites that are still a problem, we’re still having an issue, that’s when we’re talking about a need to better define the heterogeneity.

So this is an example of our traditional products that we…more that’s the standard in our industry for defining the subsurface. What you see here is a cross-section where what’s posted are the USCS strip logs, okay, Unified Soil Classification Strip Logs. And the standard for our industry is to plot those logs and do what’s called lithostratigraphic correlation. And that simply means to match up sands versus sands. And light colors are sands, the darks are silts and clays, all right.

And what this shows and this from our first case study is there’s a lot of complexity, and a lot of heterogeneity in the subsurface here. But the way we try and overcome that and get our arms around this so we can move forward is…there we go. Okay, is we identify, the best we can, any continuous clay layers, okay and identify those to separate and identify saturated zones. In this case that shows it divided into zone A, B1, B2, B3, okay.

And then we take those zones, and then we treat them as if they’re homogenous and isotropic. We use that assumption. And that’s shown by the, and implied, by the products that we use to define our subsurface and groundwater. And they’re, primarily, what you see on the left is we take groundwater equipotential surface mass. So what we’re doing here is we’re mapping out. We plot groundwater elevation data and then contour that out. As we develop those contours or draw those contours that’s what this implied assumption of homogeneous conditions, okay.

And then based on that, we define a flow direction like you see with that blue arrow. And then what you see on the right is we then plot out the chemistry concentrations. And then based on that assumed flow direction, we then plot out what’s considered the contaminant plume, okay. So, again, that’s what this simplifying assumption of homogeneous conditions. What this doesn’t really take into account is the impacts that the geology may have in controlling contaminant flow. And that’s the focus of what we’re gonna talk about with ESS.

What I’m gonna…I’m gonna take you on a little field trip here to show where we run into problems when we assume homogenous conditions, and basically ignore the aquifer heterogeneity. Where we are here, this is what you see is a…the photo is an outcrop in one of the most studied areas outcrops in Canada because it’s a hydrocarbon-bearing upper cretaceous horseshoe canyon formation, right.

Now, these are sands and silts and the sand bodies, the sand channels, those are the light colored rocks that you see there. The dark colored are your fine-grained silts and clays, all right? And that circle that you see there that’s a geologist, a stratigrapher, climbing around the outcrop mapping that out. And that’s what stratigraphers do. That’s what they study throughout the world is look at outcrops of different depositional environments that are shown on that black diagram.

We’ll see more a little later, but what I’ve circled there is this is a buried sand channels. This is basically like a buried Mississippi River meandering stream deposit, all right. But now we’re gonna look a little closer at this. Blow it up well. And what we see is, you know, and generally speaking we’re saying that these deposits, these sediments, are deposited from the bottom up. So basically you have that bright lighter colored sand unit, those are the channel deposits.

So that’s courser-grain. That’s where most of the water would flow through if that was saturated. And then in this case above it are the finer-grained floodplain deposits of silts and clays. All right. But what you need to point out here in this particular depositional environment, you see those thinner clay layers in there. Those are actually very aerially extensive. Those clay layers, all right. They could be continuous on the order of tens of meters to kilometers.

And I’m just gonna show ’em here to emphasize them. Yeah, there you see, okay. So in this depositional environment, these sand bodies, the details of the sand bodies is really they’re not been deposited layer cake from the bottom up. They’re actually been deposited from the left of the slide to the right of the slide, okay. So that’s a natural depositional slope that we’re seeing, that’s emphasized or characterized by these continuous thin clay deposits, all right. And that’s what’s called…yeah, we even have a name for it. It’s called lateral accretion of the sand channel, all right.

Now, let’s say our site, our contaminated site, is underlain by this depositional system, all right. And then what I just showed there for the example, there’s our groundwater table, and so everything beneath it, the sediments beneath it, are saturated. Now, if we were to start working on that project, the first thing we start doing is try and collect some data to understand where our contamination is and how groundwater is flowing. So for an example, here’s three monitoring wells that are streamed in that sand.

And our standard assumption is that’s the first sand, saturated sand, that will be like the A sand, and we would assume that all those streams are in communication. However, a stratigrapher who understands the depositional environment, in this case, the meandering stream depositional environment, also understands that there’s more to the details of how these sands are put together. So the stratigrapher would know to look for this continuous clay units, right. And this is the difference that in this situation, each of those wells are not in communication because of those continuous clay layers.

So well one is not in communication with well two, is not in communication with well three. So you can imagine the impact that could have on a monitoring system, on a means of trying to define where your contaminants are migrating to, and then also to the design. That’s why we have these thousands of complex sites out there where we’re not getting success, we’re not getting the closure, is we have this kind of complexity.

In this depositional environment, what I show you here is the rule not the exception. And this is something that a stratigrapher would look for knowing the depositional environment. Okay. So that’s a little background on why ESS is important.

Now, I’m gonna talk about what environmental sequence stratigraphy is. So sequence stratigraphy is a science that was developed in the petroleum industry, and I like to think that the petroleum industry evolved very much like our industry has evolved. And what I mean by that is in the early days all the geologist was responsible for was finding the oil and finding the reservoir. And the biggest challenge was at the surface, the facilities, how to engineer handling that. And it wasn’t until these, decades later, that these oil reservoirs came in decline and started pumping water. Then the economics of it was such that we needed to understand the stratigraphy, the geology. So that’s when that industry, the petroleum industry, over the last several couple decades has invested billions of dollars in research and development on the stratigraphic control of fluid flows.

That’s basically what we’re doing in our industry. And that’s what we’re talking about is this initial assumption of homogeneous conditions that serve the purpose to the degree that now with complex heterogeneous sites, we need to apply this more sophisticated analysis of our subsurface data. So that’s the science of sequence stratigraphy, which by the way now that’s the standard. That’s what taught in all of our schools as far as… In geology courses when you talk about stratigraphy, the focus is on sequence stratigraphy.

Now, what environmental sequence stratigraphy is, is that’s applying the concepts, major concepts of depositional environment and facies analysis, which I’ll talk about in a little bit, to the kind of data that we collect in our industry, okay. And it’s generally these three components, all right. The first one we already talked about, with that field trip I took you on, is about the depositional environments. We’ll talk a little bit more about that in a second. The second piece is about leveraging the data that we have, the existing data that we collected, in a format such that we can make interpretations away from the data points between and away.

And then the last step is actually mapping out the permeability aquifer architecture. Actually mapping out the plumbing in the subsurface, okay. So what this is it’s all about pattern recognition. I mentioned earlier here about the importance of the practitioner. Stratigraphers, sequence stratigraphers, trained stratigraphers haven an encyclopedic knowledge of these depositional environments And the best way to think about it is like a jigsaw puzzle. You know, if we did not have that cover of that puzzle to know that this was a scene on a lake on a lake with some sailboats, you know, for all we know it could have just been a cap, then we’d have a lot harder time putting those pieces together.

Well, same with the limited data that we get for any site. We just have boring logs, and we don’t even have all the pieces of the puzzle, right. But, again, with stratigraphers, once they determine what the depositional environment is, then they have an understanding of how the major sand bodies and clay bodies are put together in that system. They understand the geometries and the continuity, and the dimensions of these sand bodies, depending where they are, which system they’re in and where they are in the system, okay. So that’s the importance of the practitioner. It has to do, again, with pattern recognition.

Now, what I’m gonna show you is the nexus, the relationship between the data that we have, and this understanding of the depositional environments. So there’s that block diagram I showed before that has various depositional environments. What you see on the left are these grain-sized distributions, vertical grain sized distributions, where the finer grain materials are plotted to the left, the coarser grain like coarse sands and gravels are plotted to the right.

And what we’re showing here is the major sand bodies in these different depositional systems, major sand bodies, have characteristic vertical grain size patterns. So, for instance, that’s an alluvial fan and has a coarsening upwards sequence for the sand bodies that are mappable there. For a fluvial meandering river, that’s a fining upwards sequence. For braided river, braided fluvial, that’s a blocky pattern. When we’re talking about offshore, we have transgressive and regressive impact on the sand.

And then for near shore deltaic that again. So this is an example of a handful of depositional environments and then, again, characteristic vertical grain size patterns. Okay. And this just for your reference, a colleague, Mike Shultz, he actually wrote a part of the ITRC guidance document on next-generation DNAPL characterization, and part of it includes this table, which shows like I mentioned some characteristic dimensions of these sand bodies and clay bodies in these depositional environments.

So how does this connect to the data we have? So this approach, ESS is about using all the projects we’ve worked on. You know, for me it’s been hundreds since 1992 applying this application, applying the ESS. I have been using existing data. It’s usually in the form of boring logs, but CPT logs, geophysical logs, now the direct push methods that we have, those are all…they’re all representative of vertical grain sized distribution, all right. And that’s what we focus on.

There’s been several stratigraphers and geologists who’ve come over from the oil industry before. So we’ve had that kind of expertise, but where things are falling apart is this argument that “Gee, all we have are these lousy USCS boring logs. They’re not a geological description of the subsurface.” And then plus you get different geologists, different drilling methods, different sampling intervals.

What I’m showing there is, you know, the standard that we use usually in interpreting on cross-sections. And that’s a strip log of the unified soil classification system. But what we do, what the ESS process is what we take that existing data and we format it by preparing what I call “graphic grain size logs.” So this focus and what you see in the middle there is, just like I mentioned on those other log curves, the finer grain clays are to the left, the coarser grain materials plot out to the right, all right.

And this is the connection between depositional environment and being able to interpret the data that we have, between and beyond the data that we have. So what you see is for this particular log, you see the graphic grain size log bars that are there. And now let’s look at it a little closer. So you see that there is an upper SM, silty sand and that one is fine to medium grain, and a lower SM which is fine to coarse grain. So it plots out differently, okay, because of the different grain size.

So we’re able to tease all these details out of existing boring logs, all right. And now this is what we…so what the stratigrapher sees now is you look at that boring log, the stratigrapher…first of all this is March Air Force Base, and this is buried sand channel deposits. So the major sand bodies are finding upward sequences, and what you see are two from the bottom up, two finding upward sequences. Two channel deposits.

And these aren’t just a one-off. It’s able to correlate and actually define these subsurface channel deposits. And these are the course grain materials that groundwater primarily flows through, and the primary pathways for contaminants. So it’s really important to be able to map these out. And this is an example of the zone of impact, and mapping out what you see in yellow, so actually in three dimensions understanding the pathways, okay, the subsurface plumbing.

And this slide is to make the point. The one on the left is using the same data, using our more standard USCS approach of lithostratigraphic correlations. And as you can see, you can’t define the sand channels using that approach, all right. So basically there’s no way to map those out. So that shows, you know, the limitations, you know, for not applying this more, you know, sophisticated analysis and have the right practitioner.

So that’s the basis of what it is, and now I’m gonna go through two case studies on where we’ve applied it. The first one is in the Silicon Valley, and so this is a chlorinated VOC impacted site. So, basically, I got solvents at a chips manufacturing company. And similar to I showed before the geology, or buried stream channels, okay. And I already showed this. This is the original CSM and using a more standard approach. And most of the contamination was in the B1 zone. So that’s gonna be our focus, all right.

Now, what you see in that map, that map is the kind of products that I showed you that’s more of a standard in our industry where the contours are groundwater elevation. Those wide arrows show an estimate of what the flow direction is based on that. The white dot shows the on-site source area of contamination, and the red rectangle, that’s the extent of the property of our client. And the yellow dot is an offsite impact. The blue is the concentration of…oops that was…there we go. The blue is a concentration of TCE of the contaminant. The darker the blue, the greater the contamination.

So at the five-year review of this project, the EPA said that due to the increasing contamination at the downgrading boundary we see there, that increasing VOC contamination, that more source needed to be removed. Well, this is after the client had already invested the last 15 years in cleaning up the source, such that the immediate downgrading wells showed that it had been cleaned. But based on these results, and this understanding of the subsurface, there was more cleanup that was needed.

Okay. So we took the same data, applied this approach that I mentioned, a stratigrapher understanding that this is, you know, buried meandering stream channel deposits. That’s what you see up top are the graphic grain size logs. What you see below is the interpretation of the sand channels, the sand bodies which are in orange and yellow. And then the fine grain, you know, silts and clays are in grey. And this is important because, at the area of that zone B1 that I talked about, was able to actually map out two separate sand channels.

One’s called hydrostratigraphic unit one, HSU-1 is the shallower one, and HSU-2 is the deeper sand channel. And these were important because these were the channels that actually intersected the source areas. And where HSU-2 when you map that out you see it on the map above, it goes…trends through this offsite sourced area, and then to that monitoring well that’s at the down-gradient that is the down-gradient property boundary, okay. And, again, at the source area, onsite source area, they had done extensive remediation.

On the offsite source area, no remediation had been done. The onsite was bioremediation, so there was a lot of degradation and vinyl chloride, for those of you who are familiar with that, was one of the primary daughter products that’s left behind. But at HSU-2, no remediation was done, so there was no degradation at the TCE there. And this shows the flow direction in the red arrows, but the point here is the map in the upper left, that shows the pathway of that HSU-1, and how that goes through the onsite source area.

And the yellow that you see both in cross-section and up in that map is the pathway of HSU-2. And what we did then is we mapped out the chemistry to actually be able to fingerprint what the chemistry represented at the offsite versus onsite. And the primary indicator was the onsite impact had vinyl chloride in it because of the remediation that happened. The offsite did not. And when you look at the details of where these wells are screened, you end up seeing that those wells that are screened just in the upper HSU-1, they have vinyl chloride in. For those that are just screened into HSU-2, vinyl chloride is absent. And when you get to that down-gradient well, that was the point of concern, that’s because they treated that B-1 zone as one homogenous unit, they actually screened that monitoring well in both the upper and the lower HSU-1. So what ended up been determined was the higher concentrations that was above the MCLs, that was coming from this offsite source. So we were able, actually, able to map out the pathways from these different sources.

And that was already inferred and considered just by looking at the chemistry data, but there wasn’t compelling evidence because we didn’t understand the details of the pathway. It wasn’t until after the ESS was done that we were able to actually convince that…EPA was convinced and our client was no longer required to do any additional source remediation. So this just shows the difference from before and after.

And now my second case study is of a different scale. What you saw there, that was for the previous one. That was about a 10-acre site, and we’re looking at about 60 feet of stratigraphy beneath the site, beneath ground surface. Now this one is more like a 1,000-acre site, and we’re looking on more in the order of 600 feet of geology beneath the subsurface. We were brought on in this project, they had already developed the remedial action plan, and the initial design of what they were gonna do. The impact was primarily perchloric, but also volatile organics as well. But the primary driver was the perchloric because downgrading at about a mile away from the source is where production wells were producing perchloric at above drinking water standards. So the client was responsible for wellhead treatment.

So this particular part of the remedy was about plume capture. So it required installing extraction wells to contain the plume. And they already…what you see down below is that cross-section that was…the design of the extraction program was based on that conceptual site model. We came in, and first of all right away our stratigraphers knowing the depositional environment, in this case, was a braided stream environment, understood that in these depositional environments you tend to have…you can actually map out more detailed sand channels than what was lumped together in that original CSM.

So this is a network of cross-sections that were put together. We don’t have time to go through the details of the geology, but this is just to show that we are able to use this understanding of how these finer grain floodplain deposits are continuous in the area of deposition. And in this case, there’s a dip or a slope to this because this was next to…near the San Gabriel Fault. So that’s actually structure that was there. But just getting to the bottom line, what our stratigraphers ended up been able to show is that you see in yellow, those are individual sand channels that were mapped out, versus the green and blue are the finer grain floodplain deposits, okay.

So based on the understanding where these detailed sand channels are, again, that’s like the plumbing, and where the source was we’re then able to map out the pathways. Then once we have the geologic framework, then we’re able to take the chemistry data and plot it and apply it to understand how the contaminants were moving through the subsurface. And we also get a field program, where we understanding the stratigraphy did very focused pumping tests to understand the communication of these different sand channels between each other, okay.

And this is the bottom line that the original design was 125-foot long streams for the extraction wells based on this conceptual site model. After using, again, the same existing data, applying ESS concepts, we find that the actual contaminants were limited to just the upper 35 feet, the channels that were in the upper 35 feet. So when you do the calculations on an extraction system, ends up that that original would be pumping more than 75% of the water that would be pumping would have been clean water, okay. And the results is an over $50 million cost savings on a remedy, on a 30 year pump and treat system.

So that’s a completion of the case studies, but I’m gonna wrap this up first by making some more general statements about the application. I mentioned a little difference in scale. The geology is totally scalable. For instance, this shows an example of our regional scale evaluation that was done at an Air Force facility. And so three general scales that we could think about. One is regional, another is more the plume scale like this shows here focusing at the level of understanding, the fate and transport of the contaminant in the sense of the plume. And then, like I showed in that case study, remediation scale focusing in on source areas and how to, you know, cut the head off the snake and get rid of the under-skin mass flux. And get rid of most of the contaminant mass.

And then it goes beyond that. Those of you who are familiar with the issues we run into with our back diffusion, matrix diffusion. Well, this is from a petroleum publication from 2014. And this shows even to the point of going from what they call megascopic all the way to the microscopic, those characteristics are related to depositional environments, and different types of facies models, okay. So my point here is even when we might need a high-resolution site characterization to define some of these higher resolution issues, once we do that, or even before, we can actually map out where these kinds of conditions maybe using existing data.

And then use high-res characterization being able to develop a more focus targeted program for collecting high-res data.

The slide is mainly to show that the application of ESS is done regardless where you are on the remediation life cycle from site characterization, remediation design, implementation, and all the way to site closure. You know, all those little bubbles are pieces or parts of those life cycle that are impacted by heterogeneity, okay. And especially when we’re talking at the end about the end product trying to convince regulatory agencies that it’s, you know, we know enough that, you know, we could…we cleaned up the site, or we met the requirements. A lot of that is about understanding the uncertainties and the heterogeneities.

So these are highlights that environmental sequence stratigraphy uses existing data. So we don’t need new data, but we’re scientists, so the more data is gonna be collected then all the better. But the point is what you wanna do is optimize what you have with the existing data, and then we could help to high grade any data gaps analysis. And then also it’s applicable to all contaminant types because this is about defining the plumbing.

So it doesn’t matter what impact is moving through groundwater. So we’ve applied it to all of those contaminants that you see there. I’ve already talked about the variety of scales, and critical to all phases of the remediation. And then it’s considered an emerging best practice. I mentioned about the U.S. EPA paper that was published just a couple of months ago.

And then just before I hand off to Craig, I just wanna show this off too. This is about moving forward. How we collect data. I mentioned it’s this focused on geology. And we like to call it now remediation geology. There’s gonna be a technical session at this year’s Battelle that Herb Levine and I are co-session chairs on remediation geology. And one thing that was presented at the last Battelle Conference is this better approach to…I mentioned, versus the USCS there’s borehole geologic logs. And this is a collaboration with, you know, some of our folks, Mike Shultz, and Colin Plank, as well as Marie Anderson, and Jessica Meyer of the University of Guelph as well have helped develop this. That’s it. Thank you.

Craig: Thanks, Rick. So wonderful job and technical transfer. This is Craig Sandefur, and I’m going to talk about design verification. As many of you might know that our REGENESIS customers, we’ve been proposing design verifications now for a couple of years. This was based on the notion that we step back and look at our designs. And find there are reasons, there are themes as to why performances are occurring as we anticipate based on our designs and the remedial outcomes.

So what I’m gonna talk about real briefly today is kind of what you as a remediation practitioner would need to know to do a design verification and to improve your site’s outcome. To coin the term “Why stratigraphy rules,” I wonder now if it might not be, Rick, why heterogeneity rules remediation. Might be a better term. So I’m gonna give you a few terms to better understand geologic conditions, and then I’m gonna summarize a design verification program of sites that we’ve been following for a while and give you some updates.

So what do you need to know as a practitioner? Well, as Rick’s been discussing and Mike Shultz and his group are all talking about is organization of position of contaminant storage units and transport units. And this comes from whether it’s fine grain, I’m calling a storage unit, or coarse grain unit, I’m calling a transport unit. But these vertical and lateral relationships between storage and transport units, or fine grain/coarse grain are critical. They need to know as Rick has so eloquently described in the previous slides.

So I’m gonna say, in most situations, that we work for our customers as remediation designers at REGENESIS. We care about where the sand is. How much of it, how well sorted, and what’s its position in relation to the fine-grain unit? So Rick’s talked about this in great detail and I will not overemphasize it here, but these sedimentary processes control these relationships. They’re organized. They may appear random, but they’re not, and they are card cataloged by depositional environment facies analysis.

Once we’re in that…the correct area, we can start to be somewhat predictive. And we can also be predictive as to the organization of these fine and coarse grain units. So since sedimentary processes control these relationships, the mass storage and distribution of contaminants, and the ultimate shape of the contaminant plume is a result of this heterogeneity, or this organization, or in a relationship.

Since contamination is distributed by soil and positional relationships of those soil types, identifying the vertical and lateral relationships between these low and high K-zones are very critical. And so, essentially, your site and the scalability that Rick talked about, whether it’s a smaller site or larger site, this is what makes remedial design from our perspective site-specific. Specifically, hydraulic conductivity and those positional relationships. So, segueing into, well how can I better understand that? I mean, Rick’s come at it from a very detailed view.

The remediation designers at REGENESIS have conferred for a long time on what do we need to know? How do we make remediation better? Now, if we had some of Rick’s information, we had some of those great site conceptual models, it would make all our lives a lot easier. But in a lot of sites, we look at, we don’t have that level of the detail. So design verification was developed to cover off on technical gaps. These are pre-application, field verifications of the design assumptions we’re making.

They’re usually localized and are fairly high density. And they focus on contaminant transport zones unless you might be in a source area. Most of the time we’re in the body of the flow. So our objective is to improve reagent and placement accuracy, and ID and target the mass flux zones. So if you believe the practitioners out there right now, most of them are saying typically 10% of the aquifer’s controlling about 90% of the contaminant mass distribution. So if you can nail that down, you go long ways in knocking your plume body down considerably for a much lower cost.

So what is design verification? I told you kind of a little bit what it does. What it’s not. It’s not more of the same folks. It’s not the winning, the lateral and vertical extent defining plume boundaries, receptor pathways, and liability and risk. What it is it improves remedial outcomes, and that’s by focusing on identification of the position of high contaminant mass, and the associated mass flux zones. We emphasize identification of the principally impacted units resulting in better reagent contaminant contact. We don’t sweat the 5% that doesn’t matter. We sweat the 10% that really matters, the 90% conduit.

So design verification is designed to aid us as a designer to ID these technical blind spots, and I’ll talk about them in a slide. It refines our design assumption. It fits within the site conceptual model. It dovetails the site conceptual models. It helps us with reagent selection. It helps us also calibrate reagent design. So is my mass of contaminant marrying up with the volumes and mass of the reagent, the remedial solution that I’m proposing? Or a better, bigger question is can I actually fit the remedial reagent volumes in the target treatment zone?

A lot of folks miss that boat sometimes, and we end up putting more reagent on the ground than in the ground. So this allows us to kind of calibrate target treatment zone accommodation rates and volumes and ID those hydraulic limitations. One of this we like, and Rick is a big proponent of and I confer with him often on this, is continuous core logging. Recording soil types using, and I stress this, geologically based descriptions is incredibly important. I don’t know if you can see on Rick’s poster, but he has a whole section on settling tubes.

We like to look at contaminants of concern lab analysis when it’s necessary, when we see high hits on the FID or the PID. Clearwater injection, we’re gonna talk a little bit about that, and we’ve also added sieve analysis. We think that has some merit, and it’s a low-cost analysis. So I wanna talk about a few of the parameters that I think are really critical for people to understand and to start using. It’s a soil settling tube. It’s a field technique. It’s semiquantitative with a trained field geologist to be very accurate.

It’s a visual determination. It gives a relative soil particle size. It helps define sand, silt, and clays. It helps define the sands in the ways that geologists need to understand them. That is relative grain size. How well sorted it might be. It’s simple. It’s reasonably reliable and rapid and, in my opinion, it decreases subjectivity to a great deal. Especially in those mixed up transitional zones that are silty sandy, or silty clayey sands. It helps a lot. If you look at the right, you can see clay, silt, sand, fine sand and coarse grain are all represented in a single settling tube. It’s pretty easy to relatively figure out, “Hey, I’ve got fine, coarse sand with some clays and silts.” It can be fairly high density. You can do this relatively inexpensively, one-foot intervals or where you see the big transition zones.

The clear water injection test is a second method that we use extensively. It helps us document the acceptance rates and volumes. So that’s specific to the vertical target treatment zone that we’re interested in treating. It assists in application decisions.

Like, for instance, if we’re using direct push injection techniques, do we wanna go top-down, or do we wanna go bottom up? It also helps with injection wells. It helps us define the screened intervals better. Data collection often differs. The data that we collect from this often differs greatly from the hydraulic, the KH based reagent volumes estimate we’re given on our project evaluation sheets. So we often see a fairly large disparity between what we calculated, and what we actually were able to achieve.

Finally, I wanna address technical blind spots. This is where the rubber meets the road. This is where REGENESIS and our technical team feel a lot of pain because technical blind spots are blind spots. You don’t know ’em until you define them. You may think you know ’em, but a lot of times you don’t. When we perform design verification, 46% of the time we find unidentified hydrogeologic conditions. That’s a lot. Lower injection rates, 25% of the time, or decrease our lives than what we anticipated.

Unidentified contaminant transport settles 21% of the time. That means 21% of the time there’s a transport, you know, that doesn’t show up on logs. Eighteen percent of the time we see a thicker contaminant zone, but I find it’s very important 18% of the time we see a higher contaminant concentration than was anticipated. And I can tell you most of the time a higher contaminant concentration comes from the notion that you used groundwater data to do a remedial design. And just don’t take into consideration the slow mass banked on the surface of soils.

And for my final slide is simply design verification. It fits within good site conceptual model definitions and should be used in concert with a good site conceptual model. It helps refine that site conceptual model to very specific remedial objectives. It helps us refine our design assumptions. It calibrates and helps us select reagent selection, or make reagent selections. Maybe it isn’t ISCO after you do this, maybe it is ERD. It helps as calibrate the remedial design in terms of mass versus reagent…contaminant mass versus reagent mass.

And the old question, can we fit what we think we can into the entire treatment zone? Finally, you know, a critical piece is calibrating that target treatment zones, accommodation rates, and volumes. How fast do I need to pump it to keep integrity of the aquifer without fracking, and how much can I get in? With that, I’ll conclude. I appreciate people’s time. We’ll take some questions.

Dane: All right. Thanks, Craig. Yeah, that’s gonna conclude the formal section of the presentations. So at this point, we’d like to shift into the Q&A portion. Before we do this, just a few quick…

Dane: All right, so let’s go ahead and circle back to the questions. We have a lot of questions today, so if we do run out of time before your question, we’ll follow up with you after the webinar. All right, so here we go. The first question is, “I’ve come to think we should map the sites strategically before installing wells. The mistakes ESS are trying to solve seem related to this thought. Should we be looking to revise our approach to investigations to map then sample?”

Rick: Yeah, great question. Yes, that goes to the first steps that I show in the approach of environmental sequence stratigraphy and the comment about the importance of the practitioner. So whenever Mike and Colin are working on a project, the first thing they do is to look at Google Earth to understand what the surface…depositional surface geology is like. And then they go look at research, existing reports, and publications typically USGS that has interpretations of what the geology and the depositional environments are that they’re dealing with.

And once, you know, a stratigrapher gets that, they already got a model in mind. It’s like that example I showed of the jigsaw puzzle. So as soon as they know the depositional environments, they already understand something about the kind of sand bodies that they’re gonna interact. What kind of a data they’re gonna be looking for in the boring logs, the actual site data. And so the models are already being put together in a sense, the conceptual model, before they even start looking at the existing data, okay.

So I think that will address…the question is definitely. That’s if we’re starting a new project today, that’s the first thing you wanna do is first get an understanding of depositional environment, and have your stratigrapher identify where you might expect to define where the major sand bodies are, the major…where the best area is. For instance, if it is a stream deposit, you know, understanding generally what is the orientation of the stream channels.

Dane: All right. Okay, great. The next question here is, “During subsurface type investigations, I imagine you strongly recommend conducting grain size analysis on every sample, correct? If so, at what intervals, continuous, every two feet, every five feet, what are your thoughts and recommendations?”

Rick: Yes, grain size is critical. That’s, like I mentioned, the focus is when we have…when we’re limited to the data that’s already available, we focus on developing these vertical grain size…graphic grain size logs. So as our poster shows, and that’s gonna be presented, I believe as a learning lab at this year’s Battelle, that we don’t necessarily recommend that you go out and do, you know, sieve analysis. So that degree, it’s like…I think what Greg was showing…I’m sorry, what Craig was showing using things like the settling tubes, still making field calls on grain size is a good thing. But also depending on your depth of investigation and the kinds of materials, you know, it’s ideal to our other more continuous, maybe call them objective, sampling or devices like direct push using, for instance, a cone penetrometer test, CPT or geophysical logs. A very good modern inexpensive way to get continuous data. But having said that, that’s providing you have some continuous course that you take in order to calibrate those logs.

So getting back to that, no it’s a…the importance is not to understand grain size like you would need for a geotechnical study. It’s really…for the stratigrapher, it’s mainly understanding what the vertical grain size pattern is because that’s equated to the energy of the depositional system. So a stratigrapher is not particularly concentrating or needing the absolute grain size designation. Just mainly understanding relative. So that’s why things like CPT and geophysical logs are really good tools for stratigraphic analysis.

Dane: Okay, great. I think we probably have time for one more question. This question says he does a lot of the transport modeling and has worked with Colin Plank before. Is there a way there a way to map these ESS facies into a type of numerical model grid, or unstructured grid?

Rick: Oh yeah. Yeah, that’s a good question. Now, so I was focusing on the geology of course, but what’s really important is linking that to the hydrogeology. And how you’re gonna design and engineer systems. So, yeah, this focus on geology and what we call the lithofacies, and what I mean by that is saying these sand bodies, sand channels that we’re showing versus floodplain these different lithofacies, these different sedimentary bodies that we map out, they do have, you know, representative range and hydraulic conductivity.

So you could say that we can use this ESS mapping out of the subsurface in 3-D as a proxy for hydraulic conductivity. So we can do that, run some tests to define field test as well to define relative hydraulic conductivity. So then these can…the mapping and geology would then be very valuable to groundwater models for representing that in groundwater models.

Dane: All right, great. Thank you very much, Rick. So that’s gonna be the end of our chat questions. If we did not answer your questions, someone will make an effort to follow up with you. If you’d like more information about the services offered by Burns & McDonnell, please visit burnsmcd.com. If you need immediate assistance with our 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, very much to Rick Cramer and Craig Sandefur, and thanks to everyone who could join us. Have a great day.