 Well, welcome everybody to Auditorial's latest 101 webinar. It's great to see so many people lined up for this one. So today I'm on my own. I'm presenting on groundwater related issues, which is my background. And we are looking at multi-level wells for high resolution characterisation of groundwater contamination. It's a little bit about myself. So I've got a Bachelor Degree in Science and a Master's in Hydrogeology and Burmese Science, and I used to work in that area, both at catchment scale, sort of hydrogeological investigations and a lot of work in contaminated sites, side of things to be an EPA auditor for contaminated land before setting up hydraterra. And I have been involved quite a bit with these multi-levels in a number of facets. Once setting up hydraterra, obviously came very away with the technology and how to install it and also done many reviews of these sorts of technologies as part of projects. So yes, that's my background and I look forward to sharing some knowledge with you today. Before we charge into things though, don't forget the Q&A. We love getting questions from you and it's a big part of what this is all about, sharing knowledge. So to raise a question, just use the Q&A button at the top as indicated on that slide. What are hydraterra's webinar series all about? Well, we're a specialist technology provider and we believe that with technology we can solve many problems, including how to do environmental monitoring better. And because we know about those technologies, we want to share how they've been applied in the industries so we can improve the industry as a whole. We're also keen to facilitate education. So a lot of these webinars we're preparing, we're looking to ultimately have as part of broader training courses. And we'd like to see ourselves as a bit of an industry leader bringing new technologies to market and raising awareness amongst the engineers, engineering consultants and scientists, et cetera, about what can be done in that area. Alright, so that's the introduction underway. Now into the more serious side of things. So I'm going to start with the overview of multilevels, why we actually need multilevels. Then I'm going to look at the technology aspects of these multilevels. And then we're going to delve into some detail around two of Solon's multilevel products probably the industry leaders and have been used widely in Australia. Then the final part of the webinar will be for questions and answers. Okay, so multilevel wells for high resolution characterisation of groundwater contamination. What is this all about? Most hydrogeologists are familiar with these terms, but I think it's important to go over a couple of things. Really multilevels are used to help us with our hydrogeological assessments. And as part of those hydrogeological assessments, we are looking at systematic study of the geology, hydrogeology, geochemistry and contamination at a site. Okay, so there's quite a few things that come into that. Really what underpins the hydrogeological assessment is a clear conceptual model of what's going on. And it is so important to get that right when you're dealing with managing contaminated sites. But this is sometimes hard to do, right? So there is some guidance on how to undertake hydrogeological assessments. Now I've got the EPA guidance there, EPA Publication 668. I'd suggest to you that you have a read of that. It provides some guidance. Multilevels provide us with important information for some hydrogeological assessments that would be very difficult to otherwise obtain. And sometimes that data is crucial. So I'll be showing you a few examples of that shortly. So the references, here's a few references that sort of relate. Feel free to have a look at those at your leisure. I'm going to charge on a bit. I've got quite a few things to talk about today. Okay, so really the objective of using multilevels is to aid our hydrogeological assessment, right? You don't just use them for the sake of it. You use them when you think you're going to get data that will really benefit your understanding of a site. So what do we really need to understand when we're putting out doing our hydrogeological assessment? We need to understand the aquifers and aquatards. So an aquifer is a water bearing, is a rock that has capacity to hold water. Okay, so it doesn't necessarily, it's not always wet, right? But the aquifer is the description of the material itself. And an aquatard is typically a material that is two orders of magnitude of lower permeability. I think it's two orders of magnitude lower than the material adjacent to it. In other words, it's the stuff that stops groundwater flow. And we refer to that as aquatards. Apologies to those hydrogeologists in the room if I muck that definition up slightly. We also like to know groundwater flow directions and rates, right? That's important because it tells us where the contamination might be going. And it also gives a thumb indication of the rate that it might be traveling. But then we want to know the quality and we want to know the contamination status of that. And those are all very important things to understand to be able to assess the risk that the site might pose. In reality, layers of permeable deposits or fractured rock, which are often aquifers, are often isolated from each other hydraulically. What does that mean? It means that water does not move between them. Okay, they're separate layers. And therefore they need to be assessed independently. You can't drill a hole through both and screen across it. That's actually illegal. You're not allowed to do that. So you need to install multiple wells to characterize these different aquatards. So what do multi-levels do? Well, multi-levels help accurately define the vertical hydraulic gradients, right? So that's the difference between the heads or the hydraulic pressure between one layer and another. And that provides you with some thoughts about which way that water is going to move between those formations. And it also provides us with a higher level of resolution of characterization of what contamination is there in those particular layers. Okay, if you don't screen across discrete layers, then you can't really definitively describe the condition of those discrete layers. Okay, so many studies I've been involved in, people have screened across multiple, you know, fairly small lacrophers. And they've taken effectively an average across it because that water is mixing in the well. That's not good practice, right? That's not good practice at all. It's possible that you've got one layer that's got free phase in it and another layer that's clean. So that data is not much good to us. That's why multi-levels can be useful. So in summary, multi-level monitoring systems improve our hydrogeological assessments by collecting high resolution data, informing our conceptual hydrogeological models, increasing our understanding of the contaminant migration pathways, allowing us to look at the chemical distributions. And this is both in soil vapor and in groundwater. So they're really good for looking at those relationships where you might have contaminated groundwater and you're interested in how that contaminations also affecting the soil vapor phase. And they're very good at helping us with our hydraulic gradients. Okay, so that little picture on the right-hand side just sort of shows if you have multiple measurement points, how you can plot up a distribution of contamination more clearly, and also inform your groundwater flow directions. So what do multi-levels look like? Okay, so we're going to look at this in a few ways today. This schematic, and thanks to Solans for preparing this picture, really shows a pretty good summary of three sort of fundamentally different approaches to collecting groundwater at multiple discrete depths. So the one on the left is what we call a multi-level system, which is the topic of the day. It's got one casing and it's got multiple ports in it. You'll see that those ports that are in it, which are that sort of hatched pattern. I'm not sure if you can see my mouse or not, but the hatch pattern there, they have a sand screen around that. And then either side of it, that gray material is clay or bentonite, just like if you're constructing a normal monitoring well. So lots of isolated zones down one hole. Okay, so a multi-level system can be defined in that way. Multiple levels being collected within one hole. Now, sometimes we talk about nested wells or well nests. This is where you've got multiple wells and those multiple wells are installed within one hole that you've drilled, but you've got multiple casings. Now, in that instance, you obviously need to drill quite a wide hole or you need to be installing pretty narrow casings. Now, with these ones, my experience is they can be problematic. These well nests, I have installed some or been involved with installation where we've had troubles, which I'll talk to in a minute. Then we have what we call well clusters. Okay, so well clusters is effectively where you drill separate monitoring wells. You construct them as you would normally construct monitoring wells. And you have them, you install them apart, but you know, it might be across an area, you know, say five metres, something like that. That's a pretty good way to do it. The problem with doing it that way is cost. You're drilling lots of holes, so there's significant cost with it. There are also some other considerations which I'll come to in a minute. So there's sort of three broad categories, okay, of how you might collect multi-level data. The one on the left is what we're talking about today really, these multi-level systems. I'm just going to compare the pros and cons of these a little bit in the next couple of slides. Okay, so if we're looking at a traditional well and we decided that, okay, we don't need to have multi-level at all. We just want to use a traditional well and have a decent length screen. That's obviously going to be compromising our ability to extract high-resolution data that might be characterising different layers within the strata we've drilled through. The consequence of that is you can make some bad decisions in terms of the actual total extent of contamination. For example, it's quite possible that that contamination was isolated to a shallow zone, but because you've screened down to a more substantial depth, you might assume that contamination goes further down than you realise. Now, obviously your borehole logs and things help a bit, but it's a pretty common error, right? And there's obviously long consequences that come from those assumptions in terms of remediation costs, etc. So in this schematic, you can see on the right-hand picture that's a fully screened well. So I assume that might be going down five metres. And on the right-hand side, you've got a multi-level system which is screened and discreetly screened across multiple pretty fine aquifers. So obviously, if you're collecting samples which are discreet to that particular layer, you're going to get a different data set if you're getting an average flow into your monitoring well through a fully screened well. Interesting to note on the left, that's some real data that so-and-so provided to me, which shows how much contamination can vary down a profile. So these are differences in concentrations in milligrams related down profile corresponding to the schematic on the left. So if they hadn't used multi-levels and they just used a fully screened well, it's quite likely they would not have picked up that variance in the quality of the groundwater within those individual strata. So that's one big reason to use multi-levels versus one long screen. So now on the well clusters versus multi-levels. So well clusters have some potential to create preferential flow paths between them. And the schematic in front of us which shows those arrows of water flowing down through one area of screen and then across into another is hypothetically quite possible to have happen. If you think about what you've got around your screen, it tends to be your sand filter back, which is high hydraulic conductivity. So therefore it potentially becomes a preferential flow path impacting on that. So if you can avoid those sorts of things from happening, you're less likely to get errors. So that's one of the downsides of fusing well clusters. I would say though, in terms of well clusters, if you put a reasonable space between them, you're going to avoid that problem. Well nest versus multi-levels. Well, well nests, I would steer you away from well nests. Some of you watching may have had better experience with on the mind, but they tend to be pretty fiddly to install. And you tend to therefore get compromised data. And I think this schematic shows what happens. So I installed one of these up at the Anzac Park Rifle Range in Maruba in Sydney to monitor a coastal aquifer one time. And they promised me it would work. And we put seven of these tubes down inside one well. And in the end, we only had one that actually could retrieve groundwater. So it sort of put me off these a bit of experience. But you can see from this schematic what can happen. So you can get bridging. So what is bridging? It's where you've got these multiple tubes down one well and you're trying to backfill and effectively fill up voids that are in the subsurface with your bentonite, for example. But it's pretty easy to get one of those tubes because you've got so many cutting across a bit and creating a bit of a hole effectively behind it as the bentonite fills up on top of it. So you're never quite sure if you've achieved a good seal around each of these ports. So that can be a risk with these types of installation. All right. So I hope that part of things helps. So there's some reasons to use multi levels and some case studies. I thought you might be interested in just so you realize they are quite widely adopted in Australia in the Melbourne area in the basalt aquifers of the newer Volcanics. So that's the sort of Western suburbs of Melbourne. You get a lot of basalt out there and there's some good basalt quarries and you tend to get the groundwater in the fractures within that basalt. It used to be a very valuable, valuable aquifer. Unfortunately, it has been impacted in quite a few of the industrial areas with significant amounts of hydrocarbons, etc. So you can use multi levels to identify various fracture sets to see whether or not the contamination is extending down through all those fracture sets or is bound up in just some of them. And some of those fracture sets are discontinuous, so there's no reason why they would be contaminating groundwater further down. But as a hydrogeologist, you don't know which ones are connected and which ones aren't. So multi levels help characterizing that. So those have been used for looking at various non-aqueous phase liquids, you know, hydrocarbons, fuel, etc. On many sites in those newer Volcanic basalts. Just a couple of things I wanted to talk about here is they are excellent for looking at where you've got VOCs, free phase and groundwater. They're excellent to sort of look at those different components. Other sites where we're dealing with Dean apples like various chlorinated hydrocarbons, they're good for also screening at multiple levels to look at those dynamics. In some instances, people want continuous data from multi levels. Now it's not as straightforward as a traditional monitoring well, but we do do continuous monitoring senses that fit inside multi levels. So you can get continuous data from those over in South Australia. We've been involved with some investigations of saltwater impacts on the Murray River and use of multi levels to monitor, you know, which particular aquifers are hyper saline. A lot of the aquifers over there have got long screen wells that go through them that were actually designed to drain irrigation waters. So using those as monitoring wells is pretty problematic versus actually sticking down a multi level to actually work out where the hyper saline waters are. In Western Australia, we've used these to investigate groundwater surface water interaction at a particular mining site. You get some really good vertical hydraulic gradient data to help you work out the dynamics between those. And then in terms of soil vapor assessments, these have been used pretty widely for looking at VOCs within both rock and soils. They've been used for landfill gas profiling, particularly where there's been an issue identified with landfill gas sites. It helps tell you which strata the gas is moving through. And then a sort of a more interesting application in a way was on a mine site where they sometimes use what they call a wet cover over tailings. Tailings are the crushed up rock from mine processing. So you use a wet cover to stop those tailings from acidifying and producing acid mine drainage. But in this particular application, we used it to assess how far oxygen was moving through their wet covers. We set up a multi level and we used a manual device to measure the vapor in a bunch of ports. So there's a few examples of how you could use this. All right, under the technology options. So many years ago, we did a big review of this for origin energy when they were looking at ways of monitoring groundwater impacts from coal seam gas. And they asked us to look at everything under the sun. So we looked at multi levels as well. And out of that, I got a quite a good understanding of what was out there around the world. So there's a few different systems. Schlumberger have this thing called the West Bay system. There's a thing called the Fluke system, which the McCurry boys matrix drilling, I think are the distributors for in Australia. Then we have the Solence Waterloo system and the Solence CMT system, which products, which hydroterror are the distributors for. I guess if you're interested in the Fluke system or you could reach out to MatrixTron. So just a little bit about each of these. Look, the Schlumberger West Bay system is very expensive, but it can go very deep. I've never installed one myself. And I don't think you would use it much in contaminated investigation. I don't think it's ever been used in Australia. I might be wrong, but I certainly haven't come across it. So it will be unusual to be using it. But just in terms of some stuff about it, so it consists of multiple casings that you would attach together. There's many ports that you can fit to it and you can isolate discrete zones and you progressively build it and lower it into your drill hole. Looks like there's two particular sizes of 38mm one and a 55mm one. And you need to drill your hole either 75mm or 160mm in diameter. Alright, so a little summary about that one is you'll see the bottom row. It's very expensive. They are designed for long-term deployment. It takes a moderate amount of time to collect sample. Now this is moderate in the context of multi-levels. Multi-levels typically do take longer to collect samples than traditional monitoring levels. I think the big key feature of this one is its maximum deployment depth. So that can go at 1200 metres, so that's a significant depth. I won't go into too much more detail there. The flute system. Look, this is a really clever technology. It involves effectively, it's a bit like a balloon. If you look at that picture on the right, you can inflate it down into your groundwater well. And then on the outside of what you've sort of pushed down into the well are a series of ports that are held out against the side of the well. And that is clever. So that's how that works. I'm not going to talk in detail about that today. We don't have that much time. But it is clever. And there's a few key things you can do with this technology. Like you can actually, with one application, it will allow you to detect the seepage that's coming in along a bear hole. So you might put it down in a bear, down the bear hole. And it will show you the input depth that bearers contamination has come in at because it actually reacts with the sleeve that you push down into the ground. So that's quite clever. A few key features about this one. It's medium sort of length time to deploy versus the others. So, you know, it's probably not a differentiator. It might be a bit quicker in some instances. There's obviously various pumping devices that you can connect to it and the rate of sample collection will depend on those. You can go greater than 1200 meters with this deployment. I'd be interested to hear from the McCurry boys on how deep they have gone in Australia if they're on this call. What else should we talk about there? Suitable to do low flow sampling can remove relatively large volumes using YouTube sampling pumps. Waste volume load you to zone isolation. So that's an important thing. You're not having large purge volumes to remove. It's a dedicated system. So you don't have to worry about decontamination between sites. So that's pretty clever. It's quite expensive, the sample to collect. Now on to the two products that I know a lot more about than those ones, but be aware there are other options, right? So Solon's test to multi-level systems, which we've been involved in installing both of those and sold quite a few. Less of this particular one and more of the one that's about to come called CMT. The Waterloo system is modular. So it's a bit like a West Bay system. You build it in sections of casing and you'll see that picture on the right there. So it has stainless steel ports that allow water to flow in at the depths that you install them at. And you put in packers. So packers are things that swell up an isolated zone in a hole. So they sort of come in two sorts. There's chemical ones which sort of react and swell when they come in contact with water. And you have others called inflatable packers, which you inflate with compressed gas from ground surface. So the components of those are stainless steel sampling ports, and then you have carbon and packers to isolate the zones. Dedicated or portable monitoring instruments. So you can have things like vibrating wire piezometers to measure water level automatically mounted in those stainless steel ports. You have a well head, which is where you connect up to your telemetry, etc. You can also up to your sampling, up to collector samples from. So in terms of deployment, it does take a long time. I don't know, very is an emotive word, but it does take a long time. And the installations we've been involved with these Waterloo systems have taken quite a bit of time. They're really used in sites like uranium waste, radioactive sites, highly sensitive sites, which need long-term multi-level monitoring. And you put a fair bit of time into designing where those ports need to be and set them up. They're a very robust system. Everything about them is pretty serious, you know, the size of the packers and everything. So it's not a small job to install them. And if you've got a decommissioned one, you'll have to drill it out. Okay, but it's a very robust system. They do go to substantial depth. We don't seem to have, well, we've said it's an unlimited depth. You can certainly go a long, long way down. So these systems, when would you use a Waterloo system? When you need to go deep. Okay, when you need to go substantially deep. So the last one that I wanted to talk about was continuous multi-channel tubing for the CMT system. And this is by far the most commonly used multi-level in the contaminated land industry. And that's because it's relatively low cost versus these other options we've looked at. And it's relatively easy to install versus those other options. So it's a beautifully simple design. The CMT, the term continuous multi-channel tubing is referring to the tubing itself, which is a continuous extrusion. And each of the channels of that tube can be used to create a discrete port at a certain depth. And it's pretty simple to make those ports. You can just cut a hole at the depth you want. And you wrap some stainless steel mesh around it at that depth. So the good thing about that is it can be constructed on site. Because often you don't really know the strata until you go to the site, right? You're drilling and then you've got to install maybe that same day or the next day. So you don't have a lot of time. So it's great if you can build these things on site. It can be a lot more adaptive to what you find under the ground. And that is one of the key strengths of this product. It's not to say that installing these things is easy. Each of these ports needs to be considered as about the same amount of effort that you put around sealing off any well screen. In our traditional world, you've got to put your vent tonight in. You've got to put your sand filter pack in, etc. So it takes time. I will be looking at that in a little bit more detail in a minute. All right. So just going into detail now about those two, the Waterloo system and the CMT. So where do these ideas come from? Who invented these multi levels? Well, it's interesting. Normally they come out of a university. These sort of great ideas. And in this case, the Waterloo system was initially conceived by researchers at the University of Waterloo, which is located in an outer suburb of Toronto, really. So over in Canada. And they've been being used for over 30 years. So as we said earlier, so I won't spend much time on this. It's made up of modular components. There's the packer on the right. You've got your stainless steel port there. What's attached to the top of that is actually these vibrating wire piezometers. So they are giving continuous data, the one on the left. The one on the right is a small double valve pump, which is how you pump that water to the surface. So water rent is through the stainless steel port and is pumped to the surface with these very small double valve pumps. Meanwhile, groundwater level pressure is measured using those vibrating wire piezometers. At the head, you can see, look, there's a fair bit going on there on this little, at the well head, you've got various wires coming up from your vibrating wire piezometers, et cetera. So when we install these, typically consultants get us involved to do the installation because they're pretty complicated to install. When it comes to actually collecting the samples from these, you can see you've got your typical low flow pneumatic controller there on the right. That's a good way. I mean, that's the way you do it. So you use the same sort of controller that you're familiar with for any low flow sampling. But as you can see, right, it's not immaterial, the amount of effort to build one of these systems. Typically what happens is you've got the drill rig on site and you're progressively lowering this section down and you're adding in your next packer, you're adding in your next screen, you're making sure you've got all your cables, et cetera, coming up to the surface. So it truly is quite a complicated machine to build. Here's a bit of a picture just to sort of back up what I just said. Look at all those cables and things coming to the surface. You can see the casing being progressively lowered there. You've got an orange clamp on it, holding it in place on the right. You've got next section of gray casing that would be pushed down and screwed onto the top of that one that's there. So you need to take your time and make sure your sample lines and your cables are all threaded through correctly. So that's how you build them. You can see that little fitting on the left there. That's how you attach the packers to the casing. So you have seals on there. And that's so the casing attaches to the top of that packer section. Ports and accessories. So ports are made of 316 stainless steel, a single or dual stem, which means you can have pumps, transducers or open tubes all connected to port stems. That's what I was talking about before. You can use a one inch bladder pump or a 5-8 inch double valve pump to bring those samples to the surface. Pressure transducers can be read from the surface without readout or data loving equipment. Water levels are measured manually with a small diameter water level meter. Open tubes can be sampled via peristaltic pump or foot valves. Now there's these little micro foot valves that you use. So you're probably familiar with the traditional foot valves that you use, the Watera style ones. Well, these are a much narrower version of that, but it's the same technology. So the packers are used to isolate the zones, right? So in this instance, you're not using bentonite. A lot of you might be familiar with. You're actually using these packets to seal up against the wall of your hole. When you're putting in something like a Waterloo system, it's so much easier if you've actually drilled the hole with a diamond core rig. So you've got your core and you've got a really good awareness of the strata that you're installing it in. The packers use internal water to hydrate the permanent packer expansion material. So I swill up in it. The casing internal diameter is filled with water to overcome the buoyancy. So obviously as they get pretty long, if it was filled at the bottom, it would float. So they don't do that. They let the water flow up as you're installing it. That's what the Wellhead manifold looks like on the Waterloo multi-level system. The manifold organizes tubing and cabling from each monitoring zone. That's pretty important to know. So in the end, you can build these things and wonder which port, which tube at the top corresponds to which port depth. So it's very important to document these things as you go. So when you do finally get to collecting your data, you're getting it from the right port. There is this optional multi-purge feature, which allows you to pump from multiple double valve pumps that are down the well in the same time. So that does speed up sampling. So you can be collecting many samples at the same time. So that's quite clever. As I said, these multi-levels have been used in various applications. In Australia, we've used them for characterizing groundwater surface water interaction over in Western Australia. Over in the US, they've been used in various military and nuclear installations. They're used to look at saltwater intrusion, soil gas surveys, et cetera. All right. So now onto my favorite, the continuous multi-channel tubing or CMT. I think I'll just skip. The main thing out of this particular picture or this slide is to understand that it comes in two sorts. A three-channel and a seven-channel. Three-channel means you're going to have three ports. Seven-channel means you're going to have seven. Now, sometimes people like to cut two ports at the same depth and use one to collect water. And the other one just to measure the water level limit. It's not a bad idea. So really, you choose based on how many ports you think you're going to need. So you want to think that through first. In terms of installing these, though, it's fairly sonorous versus what you've just seen with the Waterloo system. So in this case, it's using stuff that you're all probably pretty familiar with. So you're using your sand, your typical filter back sand, and you're using your bentonite pellets to backfill and create your seals for those zones. At the top of it, you have these various tubes coming to the top or channels, I should say. And they've got this neat little numbering system on there. As I said, they must log just like your well-construction record. Make sure you note very carefully the depths that you have ultimately screened across the port depth. Make sure you record the lengths of your sand filter packs because that all affects the performance and the actual data you're getting out of these ports. Sometimes people get along and halfway through the thing, they decide, oh, we've actually put it at the wrong depth, and they adjust things and pull up, and that obviously compromises a lot of things. So it's very important to be planned out before you start the installation on site. So you know what depth to be standing at, and you can construct it as you like for the well. So these are ideal for shallow groundwater monitoring. So the Waterloo system we were looking at, that's ideal for depths sort of greater than 300 metres, really. But the CMT has depth considerations. So I think within here, they tell us the optimum depth. So we just like to see what they say there. Most of the CMT systems I've installed have been down to a depth of about 30 metres. And when you think about most contaminated sites, that has most of them. So it's pretty handy. So these are good for monitoring contaminant plumes. They're good for determining those groundwater gradients. And they're very good for the vapor monitoring. You can see in the picture on the left there, they're installing one. So this is mid-installation. So typically you've built this on site. You've finished your drilling. You've got your geological log and you're saying, okay, I want ports at these depths. And then these, if you look at what's being lowered into the hole there, you can see these various screens and spaces that they've put on there. So that's sort of how it works. One thing to be really wary of is when you first turn up the site, it comes in a big roll with tubing. And it's got a fair bit of springiness to it because it's been rolled up for a while. So it's good to lay it out flat, stick some sandbags on top of it, and leave it for a day just to flatten it out before you sort of really get stuck into things. Otherwise it's pretty hard to make it go straight down the hole. There's an example of what I mean. So it comes in that roll and they're laying it out on a plastic sheet on the site and then they're going to start cutting ports and things into it. Okay, so then you mark the depth but you want to actually cut your ports in too. So you typically just do that with a texter. And then they've got this CMT toolkit to actually make the ports. That strange looking sort of pipe is the thing you use to orientate and cut the starting hole into the channel and you screw in the things on the sides to punch a hole into the channel. The clip is there to actually then cut out the plastic between the holes that you've punched with the port cutter. The little red screwdriver is used to put in the expansion bungs and then these black tecker pliers they're called to use to attach the metal around the ports. Now here they are using the port cutting tool and you'll see on the right there, it punches a nice, neat little hole. That line drawn across would have been the line where they've said we want to have a port at this particular depth. The line going up the middle is to mark the location of the particular channel. Obviously, you've got to be a bit careful because there's a fairly thin wall between the channels and it's not unheard of for some people to accidentally cut through the wall between the channels which is counterproductive for what you're going to do. Here you can see someone cutting a port and pushing in the expansion bung which is then done up tight to seal the port. You see the hole below the port that's allowed to allow water to flow down the port below that bung otherwise it starts to float, I should say. Here they are putting a port screen in place so that's your stainless steel mesh. These centralises are very handy. They help keep the whole thing in the middle of the hole. It allows you to get your bentonite and sand down to the depths you need it to be at. At the bottom of this, you need to seal cubes. You use these plugs, these expansion bungs but there is a central port and that central port is effectively provided water to flow through this nosed man that you see on the right-hand side so that attaches to the bottom, water flows in through that mesh that's on there and it comes up your central tube. What we're looking at there is the fed-in channel CMT. Here's another picture of people installing. As I said, or maybe I didn't say, Hydrotera is a certified installer of these systems and we've done quite a few now. So feel free to reach out to us. How to measure as you go, right? Because you've got all these ports you're trying to construct. It's important to have a tagline which is that device on the right-hand side. You'll see there's a heavy weight. All this is is a weight on a cable with measured depths on it. So you use that when you're constructing your seals to measure the depth that you have placed your bentonite just and etc. And you write all of that down on your well construction record. Very important. At the top, that's what your finished well head looks like. And you use that to sample. And I believe we've got various sampling options here. So they have been very clever solans to developing these micro double valve pumps. You can see on the left-hand picture, that's a pump, believe it or not. That is a double valve pump. And it fits inside these small tubes and allows you to collect samples which you control those double valve pumps just using your normal pneumatic controller at surface. So these pumps are also pretty handy for collecting groundwater samples in general when you're dealing with a really, really narrow well. Like sometimes you've got what you think is a blocked well, happens from time to time. Keep in mind that these sorts of pumps do exist to allow you to collect a groundwater sample even from some sites that would appear impenetrable to a standard sort of 30mm double valve pump, for example. You can collect vapours through plugs for soil gas. That's that picture on the right-hand side there. It's one of the great applications of the CM2 that you can collect soil vapour across multiple levels. You can use mini inertia pumps which are like your Watera pumps, just really narrow ones. I've used them. They're surprisingly effective. If it's shallow enough, you can use a peristaltic pump and attach a bit of tubing to the end of that but you won't do better than about five metres below ground surface for that. The last thing there is they do have a water level metre that is narrow enough. It's got a 102 water level metre, narrow enough to go down those particular channels to allow you to collect water level data. Just a little summary on those and then I've got a bit of time for some questions. CMT versus Waterloo system. The Waterloo system is best from 30 metres to 300 metres. But as I said, technically it can go a lot deeper than that but everything gets heavy. It gets more difficult to install. The CMT system is best between, all I would have said, maybe even less than six metres depending what you're doing it in, but six metres to 50 metres. I think the way best we've done is about 30 metres using the same term. It can be installed both in overburden, soil for example, and bedrock. In terms of how you isolate the zones, if you're wanting to use packers, you can always use a packer with the Waterloo system. If you want to use it with a three channels, if you want to use it with CMT you've got to use just the three channel. That comes down to the particular diameter that they've set their packers for. You can use layers of sand and bents tonight in both options, although with the Waterloo systems I've seen they use packers a lot. Maximum number of sampling zones is an interesting one. So a Waterloo system can have up to 24 and a CMT system can have up to seven because it's only got seven channels. There's another key differentiator. Both can handle soil gas as well. Measuring depth to water, greater than six metres below ground water. You can use your 1.2 water level metre and sorry, that was less than six metres. Greater than six metres, you can use a 1.2 water level metre or you can use pressure transducers. So we have deployed pressure transducers both in the Waterloo system and in the CMT systems, which have been successful and we've installed these systems where you're just using discrete pumps or when we've had that manifold and collected modable samples from channels at the same time. So in summary, these multi-levels are quite handy to help inform your conceptual model. Obviously there's a bit more work to be done to install them than traditional monitoring wells but there's also significant money to be saved by not having to install as many wells. There was four options, technology options. We went through the Schlumberger West Bay system, the Fluke system, the Sollanced Waterloo system and the Sollanced CMT system. By far the most commonly used is the Sollanced CMT system. We can help you install those if you want to go ahead with it. We've also covered the differences between those two systems in detail. All right. So we might now move to the Q&A. Hopefully we've got some questions. No open questions. Goodness gracious, that's a first. All right. Well, if we've got no questions, I think we're just about out of time. Feel free to reach out to Hydrotera for any further information you'd like on multi-levels and how they can be used for your hydrogeological investigations. And thanks very much for joining us today. Have a good day. Thank you.