 My name is Aaron Ostland. I am a research extension specialist at NDSU in the Soil Science Department. I also have the pleasure of sitting on the planning committee for the North Dakota Reclamation Conference. So you can blame me or thank me for the programming over the last day and a half. I have the pleasure of having a PhD student join me for this last presentation on EM surveys. Beverly Alvarez Torres is a dynamic PhD student at NDSU, specializing in soil science with a strong focus in soil chemistry. She also has a focus in education and science communication. Her work focuses on innovative soil remediation research and leading the Soil Science Ladies project, which aims to empower women in soil science. Beverly brings a blend of technical expertise in environmental conservation and digital mapping along with a passion for science communication to promote sustainable practices and engage audiences in soil science discussions. So I'm going to get us started here and first off, I got a question for folks. Anyone seen one of these before? Alright, so we have a few people that know what an EM-38 is, which is one of the instruments that we're going to be talking about and its implications into delineation associated with brine-impacted soils. And so it's one instrument that is ultimately in this larger category of electromagnetic induction survey methods. And it really helps in situations like this. And ultimately the objective of today's presentation is to empower reclamation specialists to use a parent electrical conductivity for delineation of brine-impacted or brine releases and how the use of these surveys can can be implemented in remediation management and planning. So just a little bit of background, one of the primary concerns as far as environmental impact of releases of produced water is the the salinity associated with with brine. And over the last 15 years of development, we've really seen an increasing in the ratio of brine produced per barrel of oil. So what used to be in early well development, kind of a one-to-one ratio of oil to brine, we're now getting upwards to one to 30 in some cases. And so it's a byproduct of the development that we experience in the Bakken and continues to be a concern as far as the environmental risk that it poses. Basically when we're talking about produced water or brine is what we're talking about is really old seawater back from a time when North Dakota was an inland sea and the deposition of all of the algal and other flora and fauna that ultimately turned into the oil that we are after are all associated with this ancient seawater. There's a lot of things in brine, but it is primarily sodium chloride. We're basically looking at a saturated solution of sodium chloride, so upwards of 350 milligrams per liter of dissolved solids and an electrical conductivity exceeding 200 decisemons per meter. And so what we're looking at is if we can be more efficient in that delineation process, ultimately that leads to an acceleration of site characterization and a more efficient delineation process. And so I'm going to pass the mic off to Beverly and she's going to give a little bit more background on what soil salinity is and how we can understand what EM surveys are actually telling us. Well, it's very nice to be here again in another year. So this year let's talk a little bit about what is a salt and to understand the importance of why we need to delineate this situation into the soils where a solid is basically a compound that have one cation, one anion and they are held together by an onyx bonds and typically they are formed when a acid and a basic reacts together and neutralizing their charge. So basically can you Sorry, I can't thank you. Okay, so basically when you have salts into the soil, they are dissolved because we know that we have water into the soil. So when we have these brine spills into the soil, we are turning normal soils like this one into solid soils that sometimes they decrease the yield of our crops as you can see here. These photos are from Puerto Rico just to have something different to show here. And sometimes we will have sodic some conditions that are very common observed in brine spills because as we know the dominant salt in that produce water is sodium chloride. So in these soils we can see problems like drainage because the sodium basically destroy the soil structure and because of that we lost connection between the soil capillars and that decrease the soil drainage. But we can also have like saline and sodic soils. These soils can have like empty spaces as you can see in the image probably that are dominated by sodium. But once we reclaim this soil we need to be like very careful because that there can turn into sodic soils like really quickly once we drain the salts from the soil profile. So they are very interesting but also a little bit tricky to manage. But just to have a different perception into the reclamation sign we can also use the ratio between onions and cations into the soil to classify them and to select better remediation strategies. Because for example in my PhD project I am working with biopolymers and sometimes we can have better remediation effort if we know which is the onion or the cation dominant into the system in order to select the best components to do that. So here I have some image of the impact of salts on the land use and soil functions. First and I think that the most important heater in North Dakota is the decrease in available water into the soil because we usually are worried about the yields onto the crop but we need to remember that the plants and the animals that need water. So when we have salts in the soil the water competition starts between the salts and the soil so we don't have available water for the environment like in organisms. So after that we will see some soil dispersion and pore clogging especially in soil dominated by sodiums and in this image we can see how one soil aggregates just as well after adding sodium chloride into the solution and that is causing obviously pore drainage. So to analyze the soil salinity it's pretty common to use soil saturated repays because it simulates the soil condition and maximum field capacity but also in the field because we don't have the lab there we usually use the soil water solution because it's simple, it's fast, it's economically and easy to replicate. The situation is that no matter how easy is the soil water solution we are observing a lot of variability in the ECA values because it's dependent on the dissolution usage. So the preferred method and the recommended method is the soil saturated repays but it's leverage, it causes a lot of money and it takes a lot of time and effort to proceed so using the EEM38 you can reduce not just the labor but as well the number of samples and the effort and your delimitation. So now Aaron will explain us a little bit more about how we can do that. Thank you for that background Beverly. Alright so this is an EEM38 by Genomics it is just one of the companies that ultimately produces similar instruments that will be able to be used as a mechanism for conducting these electromagnetic induction surveys. Ultimately what they're doing is the meter itself is emitting an electromagnetic current and then there is a sensor dipole on there that can measure the voltage or conductivity coming back to the meter and so implementing these things in the field can look different depending on the application. In some larger scale agricultural applications you see side by sides with large sleds and you can cover a pretty good area of ground. We choose a little bit different approach for most surveys associated with delineation because hopefully we don't have a quarter section of area that we're trying to determine changes in soil salinity so that we can have an effective delineation and management plan and so it is also as simple as throwing something like this over your shoulder as you're doing a site walk and so it's a fairly limited investment in order to get some very useful information and so I'm going to take a couple slides here just to talk through some of the considerations of what you want to understand about what this instrument is telling you about your site and how that can influence the steps that would be necessary for an effective delineation of say like a brine contaminated site. So just like any field instrument it's only as good as the calibration and understanding what the interactions with the physical environment it is trying to tell you and so without effective calibration or understanding the potential interference and understanding the factors of the environment that influence the number that the EM-38 is giving you it's going to be fairly limited so we want to just cover a couple of the primary factors that will influence the accuracy of an electromagnetic survey and one of the primary ones is soil moisture so if you have a site that is going to have very variable soil moisture across one side to the next the EM survey is going to be dominated by that factor of the site and so for those cases it is helpful for there to be a recent rainfall you don't necessarily want a completely saturated soil but you don't want to be in a position where you have a lower landscape area that because of its topography or position on the landscape the soil moisture is going to be significantly different than a ridge line and so understanding that when that last precipitation happened and how soil moisture across that landscape is at the time of the survey is helpful in interpreting the data that you're getting from it one of the early applications of electromagnetic induction surveys was to look at soil texture and a lot of that comes back to the soil moisture so different textures are going to have different soil moisture holding capacities and those discrepancies or changes across the landscape are going to be picked up by this type of a survey one of the unique things that can be exploited and utilized is the depth of the electromagnetic field which is going to be dependent on the specific instrumentation you're looking at in this case some of the older models will have a two different settings so you have to kind of go at two different times to determine how deep or how strong you want that signal so you can look at the conductivity within the upper half a meter or up to like a meter and a half we're fortunate enough in the soils department to have a newer model that will do both of them at the same time and it can give you that opportunity to have a sense of the vertical delineation not just the spatial delineation of a spill which might be helpful for things like estimating excavation quantities or getting after those things ultimately what we're after is salt concentration and it is a great tool for understanding what the variability across the site is as far as salt concentration so we're going to kind of focus on going forward but some of the additional factors that you want to understand is survey design and data processing so the most efficient way isn't to in this case walk along and just look at the number and try to take notes at the same time but to pair it with other technologies like data loggers and GPS units which the newer units absolutely have those things integrated so it's as easy as having a GPS data logger a Bluetooth communication with the device which is what we're doing in the photo on the left which is actually an ag application of mapping soil salinity but you can have a simple sled if you don't want to be carrying that thing all over the place and pull it behind you hanging on to or integrating that GPS unit and collecting a spatial data set associated with the survey additionally you kind of want to have an eye on the sky so if you think that it's going to take you the entire day to do a survey of that site that is going to influence the numbers you're getting back and so if it's nice and sunny in the morning but you're still surveying when a cloud comes through in the afternoon and drops some moisture you might want to consider resurveying that area because those types of environmental factors are going to influence the overall continuity and reliability of your data as well as the humidity and vegetative cover it's fairly, I guess, easy in a moonscape type situation like this or a freshly plowed field but if you're trucking through the grasslands of Puerto Rico it's a little bit harder you kind of have to deal with additional obstacles and understand how that might influence the numbers that are coming from this one other thing that didn't make it on the list is kind of user air it is an electromagnetic survey if you have steel-tolled boots or you're taking your phone in and out or you have a big key chain on your hip those are things that you're going to want to understand and it's mostly thinking about being consistent with your approach not necessarily understanding that those things are going to have a huge change in numbers but they could influence it if you're changing your approach like you change your shoes out halfway through the survey or you decide to leave your keys at the truck the next kind of lap you come around the site so understanding just like any field instrument the variables that it's collecting and how those different environmental factors or characteristics of the site can influence the number coming out of there is pretty critical for the efficient and accuracy collection of that data and so ultimately once you're able to conduct a survey in this case this is the the map that was produced following the picture where we are pulling the unit in the sled in an agricultural setting you have an opportunity to pull transects and orientation collect that data and produce a a continuous spatial geospatial map of an area and a lot of times that comes down to utilizing statistical models like krigging in order to make a continuous map and zoning areas out and so understanding what the high end of the readings are what the low end readings are and then appropriately giving a breakdown to then map your entire area out into zones there are opportunities to go from what this is calling what this number is giving you which is an apparent soil conductivity to other EC meter metrics but it's probably not something I would recommend for delineation of brine impacted areas we should probably be considering it more just as a zoning tool where is our hotspot where is our edge of delineation and how can we use that information for kind of the next steps in the process which then comes into play with kind of the soil extraction and an actual electrical conductivity of like a saturated paste or a one to five soil solution for then getting at maybe a number that would be more in tune of making decisions based on like a regulatory compliance type of situation so this is kind of what the raw data looks like once you're walking the site and so that's me meandering across an area that had some vegetative impacts trying to understand what's going on on that site and so from there we're able to then utilize a krigging and produce a map more like this where we are breaking it down into four different zones based on that apparent electrical conductivity and utilizing those zones to then dictate where we take grab samples and so they're fairly small but from here we basically instead of what might have been taking 20 samples across a grid format to try to delineate this area through a simple walking of the site with an EM-38 a simple three samples from each one of those delineated zones gives us a really good idea of what we're working with as far as the site characterization of where those impacts are the highest and kind of where are we getting to the point of more of a background electrical conductivity and so a lot of times we end up calling this the zoning following a krigging of the data that's coming from the electrical apparent electrical conductivity there is opportunities like I said with the newer models to do some of the vertical components and so a lot of times you can get two or three maps out of a single pass and giving you an idea of what's happening below the surfaces of all which can also be utilized determining what a next step for preliminary investigation might look like for grabbing soil samples to validate the delineation process it can go as far as dictating at least early remediation protocols and so if you are in a situation where you have like an irrigation system or tile drainage you're going to want to pay attention to what that is doing to soil moisture because those things are going to pop up on your variability from the electrical magnetic survey but it also might give you a chance to say okay if I only have limited resources and I am approaching this site for the first time following this bill where do I want to go put my resources first and just making that overall initial steps of remediation reclamation that much more efficient and responsive because honestly this doesn't take more work than just your initial site walk yet you can come out with a lot more information to be efficient in your next steps for the remediation process including looking at some of the other work that we're doing in our soil reclamation laboratory of like looking at salt tolerant species and determining where those things might be appropriate and where they might not be appropriate relative to more traditional methods of kind of dig and haul for the use of amendments in some cases as well and so that's my our introduction to the use of electromagnetic induction surveys for mapping soil salinity and how those things can be integrated into the delineation process of a brine impacted site and so I'd like to thank Beverly for joining me and we can take any questions that you guys might have yeah thankfully I don't have to go back to the handy tool in that as long as you have a modern computer you can pull it off if it can run ArcGIS then no problem you got it in it is going to be determined on the unit you're using so this one is from Genomics they have their own data interpretation and conversion software it's a pretty simple package but basically it's turning the numbers that are being reported by the unit GIS database or platform and so in this case it's a three-step process you take it from the raw data into a geolocated data form most of the time I end up having that go into just a simple excel sheet where we have longitude latitude and then the associated electrical conductivity number and you can change the frequency so if you're having it ping every second or every half a second that can kind of dictate if you're going to have 15,000 lines in that excel or less and that might not allow you to actually pull this off in the field depending on the size of the data set in the survey but once you have it in that kind of geolocated excel format that's really easy to pull into I can ArcGIS and use their cringing tools within that GIS platform to produce a map like I was showing and so in that case that's what we do and it might have a little bit of a learning curve because dealing with different file file types and the conversion of those can be hit or miss depending on how experienced you are with it but I promise if I can figure it out you guys can figure it out any other questions? Yeah, in back so it's definitely not perfect but and it's going to depend on the unit and so the most experienced with the genomics units and in the case of the newer one it has two levels one is roughly a half of a meter deep and the other one can go a meter and a half or you can convert it to a half meter and one meter and so it is only we are still talking only feet down we're not going to be chasing things really far but in comparing those two maps that will produce it can give you a little bit better of a sense of are things moving differently subsoil versus topsoil and how you maybe want to design your next step of sampling based on that one more yeah yep so that's the critical part basically we use this to tell us where and how many samples we need and so almost always we end up zoning it out grabbing samples from topsoil and deeper from each one of our soil samples and so in the case of the map that I showed we ended up just grabbing three grab samples from one from each one of those zones a shallow and a deep coming back running saturated paste and then running that through both an ICP OES as well as an ion chromat chromatography in order to get specific ion and cat ion concentrations that way you kind of have to go that additional way to be able to have any meaningful numbers to to make management decisions on whether or not certain actions are necessary on a regulatory compliance or not so it's more just how can we be a little bit more efficient to get to that point to have those lab lab numbers to make good decisions well if you are well the most important part in the number of sample that you are taking from this surveys is based on the resolution that you are taking in your map if you are looking for a high resolution you will need a real number of sample like more than three nine so the USA ARS they have a model that is is that so basically there they have a couple of models where you can like determine the soil sampling design based on your easy values and you can also like calibrate the signal using that models so it's depending of what you are looking for if you are looking for something that will be used for decision-making in the community you will need more soil samples because probably you will need more how was the word that I used? I forget. The resolution of the map so okay thank you guys and with that we are going to wrap up the 2024 North Dakota Reclamation Conference I do want to take an opportunity to thank our sponsors one more time so thank you to Metalark Environmental 2x, Stantec, KC Harvey, B&I Cole, Chisak Seed House, Midwest Erosion Control, Bar Engineering and Martin Construction without their support we won't be able to pull you out. And I thank you guys for your attendance. When you get back out of the back home or back in the office please take a moment to answer the email from Miranda Meehan and fill out that survey so that we can get some feedback from the conference itself. And if you are here for Chase's discussion at the beginning of this last session we are asking that you participate in his survey so that we can get a perspective of Reclamation happening here in North Dakota. It will really help him in his PhD analysis of where we can be more successful in Reclamation in North Dakota so it would be greatly appreciated if you took a couple minutes to fill out each one of those surveys. Thank you all for coming and safe travels home.