 Well, hello everybody and welcome to another Hydrotera webinar. Really appreciate you all joining us today, another great crowd. Today, the topic is all about tailings dam monitoring and we're joined by two people who have done a lot of work in this area. We've got Gavin Mudd from RMIT, who's an associate professor there, but more importantly Gavin has a very strong background in hydrogeology and a PhD, which sends it on a topic around tailings, like these ash ponds down in Gippsland. But a wealth of experience also dealing with mine sites more generally, particularly from an oversight perspective. So really looking forward to his take on tailings management and where the world is at. And we've got Steve, who has also got a huge amount of experience in the mining sector and in monitoring instrumentation. He's currently working at Hydrotera as one of our principals in integrated systems. He's worked very extensively with monitoring systems around tailing stands. So we've got Gavin, who can give us a sort of global perspective on what's required to improve, but also maybe the sources of problems with tailings. And we've got Steve, who has got a lot of experience with how the area state is, et cetera, and monitor on the ground. And between those two, I think it'll be a really good presentation. So thanks very much to both of you for joining us today. So I've gone over those. Before we charge into the actual presentation, a couple of things. So we love your questions. And we've been getting lots of questions, which is great. In terms of raising a question during this forum, if you can please use the Q&A button and type your questions in there. I will read those questions out to the speakers at the end of the presentation. And between the three of us, we'll endeavor to answer them. If we can't answer them, we'll send you an email later on with the answer to the question. Why does Hydrotera like doing these webinars? Well, we actually really do enjoy sharing knowledge and love getting speakers in who have a wealth of knowledge. We learn from it. They get to expose their knowledge to the industry and the industry learns too. And I think together collaborating in this sort of forum does help everybody. We like to facilitate education. There's a bit of a shortage of really good applied training in some areas around this and there's also a bit of a loss of a lot of knowledge from the industry with people retiring and that sort of thing. So we love to get that knowledge shared through the industry. So trying to help with educating. And we also like to bring new technologies in and show people what's coming and what's available that can be used to help provide some leadership around the technology application sort of things. So we hope you enjoy it today. All right. So there's two sort of main parts to this topic. Gavin's going to lead us out talking about tailings, dam construction techniques and failure modes. And then we shift over to Steve, who's going to talk about instrumentation and monitoring, including the types of instrumentation, the installation and the data logging side of those instruments, including some telemetry. Then we'll move to Q&A, which if it's anything like the last webinar that went on for about 45 minutes. So hopefully we get plenty of questions from you today. So without further ado, I will pass over to Gavin. And thanks very much for joining us today. No worries. Good day, everyone. And thanks, Richard. So it's a pleasure and I'm very happy to help you. I guess I've been looking at tailings and pretty much my whole professional life. And I guess there's a whole range of questions. But it's a problem that hasn't gone away. And in many ways, it's actually getting bigger. And some people believe it's getting worse. But obviously we need to be doing better. And so I think hopefully my sort of short few slides here will help give you a better sense of that and what we can do. And then also why we need better monitoring, I guess, as well. So next slide, thanks. There we go. Now, I think just as a framing point, I mean, obviously, mining gives us the metals, the minerals, the energy that we need. And the technology that we're listening to on this webinar is probably a mix of about 60 different elements that make up either a laptop, whether it's the batteries, the screens, the circuit boards and everything else. And so let alone all of the infrastructure we have with our cars, our homes, our buildings and everything else. And so that comes at an environmental cost. And that environmental cost with mining tailings is certainly one of the biggest areas plus waste rock as well. And so depending on the mine and the metal, there's an enormous variability around all of the characteristics of tailings. But I think even some of the more recent disasters, such as Somarco, have highlighted that even if something is not chemically toxic, it can still cause significant ecological impact because a tailing stand failure like Somarco smothers an ecosystem, prevents light from getting in, prevents oxygen from being available in that ecosystem. So even if something is not chemically toxic, we still have to recognise that tailings can be a problem. So when you're looking at the different metals, they all have their own story. But gold mines, we're dealing with grams per tonne. So for every tonne of ore you process, you get a tonne of tailings, pretty much. With iron ore, probably 80, 90% of the material you process becomes saleable product and so only 10 to 20% actually becomes tailings. So there is that sort of variability right across the industry. But we need to understand all of these, I suppose, the characteristics of tailings, how they're produced and so on. But largely we still pretty much manage tailings in the same way we have for decades and that's an engineered storage dam. And there's a lot of analogies in the way we look at hydroelectric dams and the way we build those or water storage dams. But there are some key differences because those are storing water, whereas of course the tailings dam is storing solids and water. And this is the typical engineering approach we used to building a tailings dam. Mines typically start small. So you go upstream. So you use on the top left here, we start with an initial starter dyke and then we keep adding new dykes on the upstream side of that dam or downstream where we keep adding downstream. So we increase the area of that dam and so on. Or you can see examples on the right hand side where you have hybrid approaches as well. So all of those speak to how we engineer and we design and construct our tailings dams. In some parts of the world, like Chile, for example, upstream delines are banned because of earthquake risk. So certainly some people advocate that upstream should be banned everywhere, but I certainly don't do that. But again, we need to make sure we understand the engineering of all of these designs and make sure it's designed properly, built properly, operated properly and decommissioned properly. Next slide, thanks. All right, yep. Now, this is just an estimate I put together when I was involved with the U.N. environment's global environmental outlook a few years ago. And what we're trying to basically show here is if you look over the past couple of centuries, so the main sort of line there in the dark purple, the presentation is not that sharp, but that dark purple line is the ore grates. In other words, the percent copper in every tonne of ore that's mine. All right, and so when you're looking at the amount of copper production, along with the amount of tailings that we're producing to produce that copper, there's the other two lines which are just growing exponentially. So if we look a couple of clicks, you'll see the sort of arrows coming in here and the patterns are pretty obvious. So if you've got the decline in grade over the long term and then you've got that increase, that exponential increase in the amount of tailings. And I think one thing that's always worth, as a good thought exercise, extrapolate those trends for the next 50 years and see where we get to. So we're already producing a few billion tons a year just for the copper sector. So that's a pretty extraordinary amount of waste. And so if we add all that up, we're dealing with billions upon billions and billions of tons of tailings just for the copper sector. OK, next one, thanks. Here's our little animations. There we go. And just a few clicks. Here we go. So there's those animations I was talking about. OK, so again, these are the sort of trends we know. And if you look at different examples around the world, each of these have an interesting story behind them. But the top right here, the main sort of panorama there, that's in South Africa, where they're reprocessing old gold tailings. Where if you look at the Witwatersrand, it's basically Whitewater River. If you translate that literally. And so these areas used to be springs. They used to be wetlands, and so they're now all full of tailings. And so gradually the gold industry in South Africa is reprocessing these tailings, shifting them out of these areas where they're fully engineered. They weren't required to do much, except just deposit the tailings there back in the old days. And so now they're basically trying to remediate and rehabilitate these areas and hopefully get to the point where they can restore some of these springs and these wetland systems in the area. And so other examples there in the the bottom middle there, you've got the Mount Keith tailing stand in West Australia. And for a sense of scale, that's about five kilometres across. Pretty big structure, that one. All right, the top left, you've got the old tailings stand in the centre of Norseman in WA. And the bottom right there is the Golden Cross Mine in New Zealand, just near the Wahi Mine, a few hours southeast of Auckland there. And so it's an example of a mine that's been closed and rehabilitated and seemingly a good job, I must admit. And so there is a residual acid mine drainage problem there that they do actually have to treat the seepage water coming out of that tailing stand to make sure it's acceptable for the receiving environment. OK, next slide, thanks. Now globally, we keep seeing headlines. And I think, you know, I think the day after Jagusfontein happened, when Richard happened to ask me to do this seminar and Richard hadn't heard of that yet. So I think we're still seeing these sort of these really bad accidents. And the last news I saw, I think, was 78 people killed from the Jagusfontein failure. Now, one of the problems there is that was a mine that was closed in 1971. And it was sold last year and transferred ownership from a big mining company to a small little junior company that represents a community. And so now they've got a tailing stand failure that from a site they never operated, they have no financial capacity. And so how does government deal with that? How do we make sure we've got the financial capacity? We've got the we understand the liabilities and the risks and the monitoring is still ongoing. So I think that's a huge problem. And who decides what's an acceptable risk? And these are these are really important questions that certainly the very recent disasters in either Brazil now this year in South Africa. But again, we've had our own failure here in Australia, Acadia as well. So that's led the industry to say we need to be doing better. So they've set up a new global tailing standard internationally environmental groups have basically put out their own, which they call safety first. And again, there's different opinions on who's is better or whatever. And these are working nicely. These are just some animations of how tailing stand failures happened. And again, the reason why we monitor and it's one of the things I guess I'm always sort of explaining to my students, it's not just the cost of monitoring. It's the value proposition that that generates. All right. And so if we're looking at the value of now that we're getting for that investment in monitoring, we're preventing these types of failures. One of the reasons we do maintenance in aircraft or all sorts of things, we make sure we have the data to show that things are safe. And so when we're looking at monitoring, there's a whole range of different potential modes of failure. We can see the top left is basically an earthquake or a seismic event. We can see on the top right, that's a piping failure. We can see over topping on the bottom left and also excess pore pressure on the on the bottom right. So all of our monitoring is designed to give us information so that we can say, right, this is how we can see a potential failure occurring and we can make management decisions accordingly. And so prevent, ideally, prevent that accident from occurring. Next slide, please. Here we go. Just click through those and again, just acknowledge Peter deal for that. And in Australia, we have had our own failure. I think in many ways we really dodged a bullet here because we can see where that failures occurred on that the southwestern corner of the upper tailings dam. And if that happened to be much worse, it could have cascaded and caused quite a catastrophic event. So in many ways, quite lucky there. Now, what that led to is basically the use of the old Cadillac Hill open cut as now the storage site for the tailings stands and old tailings stands also old open cuts can be quite useful in terms of tailings stands these days, but they do have a finite capacity. And so the other problem with Cadillac that has emerged is, of course, dust, you no longer depositing the slurry, the tailings, you no longer have the water on top of the tailings. And so therefore the tailings are drying out. You've got a dust problem. You now have to manage as well. And so again, you can see the scale of these facilities. They're pretty big. Next slide, thanks. Now, typically when we looked at our guidelines, we have fairly stringent guidelines here in Australia. We have our own Australian National Committee on Large Dams all. So I think how we deal with the legacy issues and the significance of Jagger's Fontaine is it raises this issue very explicitly. So if we think about 50 years from now, how are we still going to be monitoring and managing our tailings stands? And I think that's why it's a really important question that we think about how do we fund the monitoring, who manages that data, who makes decisions based on that data and so on. So that's something that I guess we need to have a very broad conversation about. Next slide, thanks. So the typical approach we've always used is based on our engineering approach. We've used our groundwater monitoring. We've used geotechnical approaches. And that's largely focused around either water quality or physical stability. We've often used modeling as a part of that. I've done that myself. It's seepage modeling or all sorts of things, stability modeling. And that's served as well. And I think we have to acknowledge that, but increasingly it's not enough. It's like necessary, I guess, but it's still insufficient and especially when we're dealing with legacy sites. And so I think we have to evolve. And I think that's one of the things these days is that there's a lot more tools and I suppose the acquivers in the boat or bows in the quiver that can actually allow us to monitor. So these are just some examples. I've just pulled them out from various reports, but again, we can see the groundwater monitoring, whether that's sort of pH on the top one or salinity, for example. And on the right-hand side, we can see a particular solute. And we can see that you're starting to see breakthrough. So on the right-hand side, you can see that the tailings dam, this bore is monitoring the tailings dam. And you can see for about close to 15 years, it's no impact. And then after 15 years, you start to see a gradual rise in concentration. And so that's very, very significant rise there. And so that's a bloom. So we're seeing seepage impacts from that tailings dam. And so from an engineering point of view, we would say, well, what remediation might we need? Do we need a pump and treat system or an in-situ treatment system or something else? But monitoring gives us the data on which to be able to make these decisions so we can minimize environmental impacts or other issues. Yep, next slide, thanks. So when you're looking at the recent dam failures, whether it's Simaco or Brumadinho, they've really highlighted that we have to up our game. We have to get much more real-time monitoring, but also a whole range of different technologies. Juggers Fontaine was able to be predicted from satellite measurements. So if you look at INSAR as one technique, but the same with Brumadinho, right? Brumadinho, the modeling showed that Brumadinho was metastable and was probably going to fail. It was a matter of when, right? And so when we're looking at these types of things, we can use all of these different technologies now as a way to try and predict which ones are catastrophic risk of failure very, very soon. Others maybe take longer. So it should allow us to really get a better handle on, I suppose, what are the high-priority sites? And really, has the engineering worked? Are things stable? Is there a risk of a catastrophic failure or not? And so the instrumentation monitoring, I'll handball that to Stephen a second. But I think another important principle that's really, I think, become much more firmly established is the need to have public reporting. If you've got communities, and it's the same here in Australia, is in all parts of the world, I think it's a fair thing to say that they want that transparency around reporting and the data being made public, right? So I think there's traditional approach where a lot of that assessment of the data and the monitoring and so on was held between the company and the various government agencies. I think in order to make sure we've got a better case to say, yes, our tailings stamps are safe. Part of that is the transparency and accountability for that. And so the monitoring data and the public reporting of that I think is a really important principle. And that also underpins our financial liability. If we've got a tailings stamp that's safe, then the liability should be pretty low. But if we've got tailings stamps that we can verifiably show and need work or that liability should be higher. So we can help justify some of these financial aspects from having that better data and so on as well. Next slide, thanks. So if we look at globally, mining is producing the order of at least 10 billion tons of tailings a year. And that's dominated by sectors like the copper sector and the gold sector. But Australia were very much a part of that. So as Katie has shown, and there's other examples across Australia as it was around the world. And I think our typical approach is they've been, they're still important, they're still necessary absolutely, but they're not enough. And there's certainly not enough to really assure communities or investors or regulators that tailings stamps are safe. And so I think that's why we do need a lot more new technologies, but also realize that it's never gonna be just one size fits all. We need to have a plethora of different monitoring systems in place. But ultimately it comes back to making sure we're managing liability. We've got public reporting of all of that information. And so that we can have confidence in what's happening. So over to you, Steve, thank you. Okay, so let's go back to my pretty picture. Thank you. So that is a typical tailings operation. You can see that the one that was under development was TSF-6, five times before the built tailings stands in the outgrown. Next slide please. So in a lot of cases, oh, sorry, it's good to have the luxury of putting all your instrumentation sorted in during the design phase, but sometimes it's not. And that photo is of a site I went to where it's got this beautiful curved slip failure cracks occurring at the top of the site. And there's some seepage down the bottom that go with it. And they had to do a bit of mucking around to make sure that wasn't gonna fall down. When you choose an instrument, you got to pick one that's gonna work over a long time. And you got to make sure it's stable. If you've buried something under a couple of hundred tons or a couple of thousand tons of waste, you're not gonna get that instrument back. You're gonna pull it out and recalibrate it. So you got to be very careful about what instruments you choose. When you place your instrumentation, you have to allow for future construction, raising walls, putting a riprap on and dropping rocks on your loggers and things like that. So to try to avoid all of that. So the selection of what you choose and how you implement it is quite important. Next slide please. So for measuring a phreatic surface, which is to do with pore pressures, mostly we use pressure sensors and typically I'd use a vibrating wire because that gives you the best stability. This is on that site that we saw the photo of at the start and you can see we've run some very long cables through sand and up the tailings wall to a data logger. And that's gonna be there for a long time. And so these sensors typically go around the dam floor and it bearing depths around the dam walls. These are the areas where we expect pore pressure to show its head and often monitoring at the toe of the wall on the outside. Now, when you decide where you're gonna put your sensors, you've got to also decide we also got to have a think about the geological structure under the dam and around the dam and with you've got equifters and things like that. It all comes into the placement of the instrument. And like I said, vibrating wires is my preference. It's quite a simple technology. It doesn't drift, doesn't let it be recalibrated at intervals and can remain stable for very long periods. And it's also, it's largely immune to the effects of cable leak as opposed to voltage or something like that. So next slide. The other instrumentation we wanna put in sometimes is to profile the movement of the wall. So there's a couple of ways. One I've had some exposure to is shape arrays which is not the best photo, but that one with the green box on top. And that's an array of accelerometers. And if you get any ground movement, the accelerometer will change orientation and you can calculate from those changes in orientation how the wall is moving or not moving. A cheaper solution, but requiring manual intervention is to use inclinometers. You basically drill and install some casing with slots in it at 90 degrees and you run your little trolley down that casing and you measure the deflection as you go down and pull it up, put it in the 90 degrees, cut it down, run it up, put it in the 180 degrees, put it down, run it up and in the 270 degrees. So you get a bunch of readings that will tell you at any depth what the movement is and you're monitoring for changes. So that's ground profile. Let's move to the next step, please. Now, once you've got cracks happening and you've got something dynamic happening, you would use something like I show there which is a crack displacement monitor. And essentially if that peg on the earth stake moves away from the support stake, you know, you know about it. There's a couple of weaknesses with that which is if you've got clumsy miners working around there or wildlife to trip over that wire, that's gonna mess things up and scare the daylights out of people. And I've also seen a resonant frequency during the wind and vibrate. In one installation in the northern part of Western Australia, we had some serious concerns about stability. And this was connected to a data logger which in turn was connected to a mine site radio. And if the data logger ever detected too much movement, it would turn the radio on and the radio would make a prerecorded announcement for everybody in the pit to get out of dodge. And until the geotech had gone around and checked whether it was real or not. So very good technology for instantaneous results. If you've got some dynamic changes happening on your side. Okay, next one. And the newer technologies now, you're getting remote sensing. So you can use radar and satellite imagery and photogrammetry which is coming good with the ubiquity of drones. Now you can fly over and using photography. You can build a 3D model and you can observe changes and that works well. It's also good if you've got contractors on site that are moving dirt around because you can calculate the tonnage of how much they moved and where it's going to and coming from. All right, next slide. So installation. Another thing you've got to put a bit of effort into because that ground is going to settle, it's going to move and you don't make sure you don't break those cables. So the image on the left is cable was pulled through steel pipe to protect it. You can't really see but in the background there you can see that they're using rock for facing and capping and all that sort of stuff. We don't want rocks to touch your cables at all. The one on the right was a cast structure in the middle of the dam and we had to put a sensor below that and you can see we've got big, heavy steel pipe concreted it in, we've covered our cable, protected it from any sort of movement so that none of that rock is going to damage the cable. And plus also, I should say on that site that was all installed while construction was still in process. So we had to be very careful about machinery movement and stuff and there was one particular operator who copped a lot of flak but continually tearing up our cables. The piezometer itself has to be protected and typically that would be installed in a sand-filled sock that maintains permeability and if you're grouting it, you're using a bentonite cement which also maintains permeability. Then the other thing to be careful of is you have to place your instruments and survey them so you know exactly where they are. You can't just slap them in the hole and think I've got a reading that's good enough. You're going to build a model of the internal water surfaces, the phreatic surface, you need to make sure you know exactly where those sensors are. And the final thing to be careful of is lightning activity. If you've got your mine site out on a very flat plane where thunderstorms roll across, having a spider web of long cables in the ground makes you vulnerable to nearby lightning strikes, creating potential differences between the sensor and the logger and damaging things. So you need to do some careful design for how you manage that and how you protect from that. Okay, next one. So we've got our instruments in the ground. We're looking after them. We want to decide how we're going to record the data. The simplest technique is to send the junior engineer out of the box and take a reading at intervals. And on most sites, the parameters or the readings don't change all that fast but once or twice a week or once a month even is easy enough to keep track of what's going on. But in these lazier times, we can put data loggers in. So the one on the right is the data logger that has to be sent that every same junior engineer out to at intervals and getting downloaded to a laptop. And you would typically log at six to our intervals or something in that order. The other one is where we had some sites that were a long way from anywhere useful. And so we put radio links in. And so on the top of that antenna there's a five gig radio link back to base. We've done some work recently with Laura-based networks, low power, long range. And that shows promise. One of the disadvantages of Laura is it's not a high speed network but one of the advantages of these applications is you don't need high speed. So next one, please. I should also mention that some of these Laura devices will go 10 years without a battery change. So pretty much set to forget as long as the data keeps pouring in. Next page, please, Richard. So that covers, that's a bit of a quick coverage of things. So some of the takeaways from what Gavin and I have spoken about. Do you want to talk about your stuff, Gavin? Or do you want me to just do it? I can reach myself, there we go. Yeah, I think we have to recognise the problems getting worse. And that way we're producing more and more tailings. And I think we have to make sure that our monitoring, our management is also modernising, also growing in the way that we deal with that. So I think the way we've dealt with tailing stamps in the past has been pretty good but we need to do better. And I think that's probably a key message from me. And then I just want to conclude by stressing about good installation and good instrumentation. It's important to do it properly from the start. And don't neglect the system. I actually have seen systems where they're working okay and then the new engineer leaves and people forget and the spiders get in there and the rain gets in there. Suddenly something's starting to happen and you go out looking for your data and you discover that things haven't been downloaded for a year and batteries are flat and all sorts of nasty things have happened. So please, even though things aren't super dynamic, don't neglect your system and accidents happen. On this particular job, the guys in the loaders were very rough and they kept tearing up my bloody cables. And I was a long way from anywhere and it was very hard to get jointing kits and yeah, that's tearing my hair out. That's why I am what I'm like. So just the last point there is that Ryderterra have a wheeler stick which is using electrical gradients through ground to measure water flow. And some of these newer technologies are holding good promise for ongoing monitoring. Well, thanks very much, Steve and Gavin. That was excellent. We have quite a few questions coming in. So we'll move to Q&A, but I'd like to ask the first question which sort of relates to your comment initially, Gavin, which was that we've got a lot of good tools like modelling and we've got good at designing these things. And then we've had Steve talking about frequency of measurement and locations, sensors. But sometimes I think the piece of the puzzle that isn't always documented and I would have thought that the people who should be documenting it would be the people who did the original design pair is just the location and frequency of measurement to confirm that the design is actually performing as expected. I would have thought that should be tied in and mandatory on all tailings, dam design. So I was just a bit curious because we had a project come across our desk and a couple of weeks ago where the design had been done but the monitoring locations and measurement frequencies hadn't been spent. So I'm just wondering what your view is in terms of what best practice design is. And does it also constitute the location and frequency of measurement? I would think so. Certainly in my experience, I've put different minds all over the place that often different aspects are done by different groups so that sometimes they're not joined together or things like that. But I think certainly at some sites I know really well there is extensive documentation but it's often held within the company or often shared to the regulator to verify things like safety or environmental compliance and so on. So I guess there are sites I've worked on where that isn't the case at all. And so there's a reserve, I suppose a disconnect between some of these types of aspects of the way we build, design, operate and monitor tailings dam. But I think given the scale of the sort of facilities we're dealing with now and they're generally getting bigger and bigger all the time. So I think that means the risk is getting bigger and bigger all the time. So I think we have to get a lot more systematic and a lot more comprehensive in the way we make sure we get all of this right. So I think that's hopefully one of the key things. Thanks for that. I'm just going to check if we put the early bird questions. Yes, they are. All right. So thanks. We've got a lot of early bird questions. So we've got a charge on. Got 14 questions lined up already. So the early bird questions let's get stuck into that. So these are questions to both of you really. Is it still a problem in the mining industry that they attempt, can you see that at your end Kevin? Technical problems. I can see it Richard. So is it still a problem in the mining industry that they attempt to use their tailings dams for water storage? I haven't actually seen tailings dams used for water storage. In most cases they decant the liqueur out of the middle of the dam and put it into an evaporation pond just to make sure that they don't get too much poor pressure and the problems associated with that. Does that answer the question or do you want to add something in there? Some extra thoughts. Certainly there are some dams where there's a much bigger build-up of water than expected and that can certainly exacerbate seepage problems at some sites. But typically water storage, no, I mean tailings dams are built largely to store the solids and depending on the site and the climatic context and so on there's a lot of variability there but for the most part as you're saying Steve, I think the mines are managing their water balance. It's a significant risk if there's too much water in a tailings dam. A lot of our failure modes revolve around water so we don't want to be storing too much water in our tailings dams and often that's going to be poor quality water. So we don't want to be building up a lot of excess inventory of poor quality water either. So typically I think these things are sort of fairly well understood but a lot of that is very site specific and so a lot of that needs to be very carefully monitored and assessed at each site. Okay, so I can see my questions now Steve. Take over again. Question two, other types of dams for products such as industrial waste. How viable in central Australia for cattle stations? Not sure, probably a bit beyond my sort of thinking I would guess but it's some cattle stations that normally wouldn't have large storage dams. I mean you've got large water storage dams for things like cotton for example but not sure about that question. Any other thoughts Steve? I'm not quite sure what the question is because industrial waste usually carted out of urban areas and central Australian cattle stations are usually a long way from urban areas. I would think that would be more a canonical way of dealing with industrial waste. Let's have some lateral thinking though. All right. Next question, seepage management. I guess they're asking about how to manage that from where you have seepage occurring. I've got first if you like Steve. I think the first point is there will be seepage. The question is how much, where does it go and then what impacts there are. I think that's really the way we have to frame seepage. Now my engineering point of view you always want to minimize the amount of seepage and if I had a dollar that I sold every tailings dam doesn't leak I certainly wouldn't be rich but I'd probably be better off. So I think we always have to assume there will be some seepage and then work out where it's likely to travel to and what the potential impacts of that are and there's certainly some cases of mines I've worked on where those where it has been very badly managed and there's some sites where it's been very well managed. So I think you can certainly see the full spectrum there but it's an ongoing problem and it's something we need to be very fussy about I think. In most cases I've seen they've put a tow drain around the base of the wall and moisture sensors. So I didn't mention moisture monitoring but you can stick them in the in the drains and give yourself an idea of how much almost free water flow is in that drain. Take it away and again pump it somewhere where it can evaporate it or deal with it. And we've used the STF tools like Willowstick to track where the seepage is actually going. It's effective for that application. So there's a few different ways to manage seepage obviously some instrumentation, some physics. Okay on to the next question mine closure and monitoring aspects. I guess this is after we've closed how long should we monitor for and how? What's your view on that? How far down the rabbit hole do we want to go? I don't think we've got really many case studies where we've monitored beyond 10 years. I don't think that's something that we need to fix. We need to be monitoring for a lot longer than 10 years and Dacus Fontaine the failure occurred 50 years afterwards. Now when we're looking at what means for modern minds and Cadia or many others of the different dams that are out there we need to be thinking about monitoring for decades beyond and I think that's something that we're only just starting to get our heads around. How do we finance that who's responsible reporting the data and all of that sort of stuff. So all of those things we know we need to keep monitoring whether seepage whether stability whether ecological restoration of the cover of the top of the tailings dam for example there's a whole range of things we know we need to keep monitoring for. How long we keep monitoring for will be very scientific but we need to make sure we've got to a point where we're stable where it's safe and I think that's going to take decades. And in terms of monitoring too I'd also be interested to see how many people here could get their hands on it Windows XP laptop running some downloading software from a company that's been long disappeared or swallowed up and that's that's part of a 10 year thing you know like I wouldn't give much more than 10 years for any operating system and data loggers if they you know if they've been orphaned in the process and no good here anymore. Yep. I think that's a really valid point along with the maintenance of those systems often ignored and slowly mature the networks go offline I was interested Gavin you made a comment earlier about you know that typically it's the regulator and the mind that other people who know what's going on and then but why is that an issue really like the regulator's job is to regulate them don't you think that putting it out into the public domain is potentially going to confuse people rather than help the problem like isn't the regulator qualified to assess the problem and aren't they acting on our behalf. That's a great question Richard but regulators sometimes get it wrong companies sometimes get it wrong and sometimes communities get it wrong I think we have to be honest about all of that and so Mount Poly is a great example of that where the regulator and the company both underestimated the potential for failure there the consultants to the company there had actually seen it and they'd actually written to the regulator saying effectively in Morse code but yes we're worried and that worry was not acted upon so I think there are times when we do get it wrong and that's how we've got failures and so I think we need to be asking that question so right well we need to make sure our regulators are resourced they've got the expertise there and same within the companies and I think that's been one of the things that's been really good to see over the last couple of years is a real reinvigoration of commitment to expertise and careers within tailings dams in the big mining companies so I think we need to be doing all of that and more but I think another part of it is that transparency because there are commitments or promises being made whether it's to communities or investors or regulators about safety so we need to make sure that there is many eyes on that as possible and I think that's the way we can get the best safe outcomes It's been interesting to look at the various models that have been tried like almost independent oversight committees and I may have been involved in a few so I think the model probably exists but maybe it needs to be mandated across the industry better move on to the next question sorry so IOT and connectivity options for sensors in tailings dam monitoring that's probably my area yes I'm seeing now low power wireless coming into use last time I did used RST product it's a Canadian company and they are using ZIGV which is a bit like Laura and we got very good connectivity with a couple of base stations and they were in fact telemetering their data out of the loggers into their SCADA system with alarms and all the usual stuff works well and it's getting better what about satellite side of things Steve are you seeing that being used more I'm just trying to remember if I've seen much in the last satellite satellites up to now has been quite expensive and for a site that's got 10 or 20 or 30 sensors around the dam wall it can get quite expensive and certainly cheaper to send the junior engineer at times so with anything electronic you've still got to maintain batteries and solar panels and all that sort of stuff so there is an ongoing cost no matter how simple it makes the gathering of the data it'd be interesting to look at that again in the light of some of these micro-satellites that have come out in the last couple of years just in terms of whether they can be applied for this sort of monitoring certainly some more in that area the question to ask is are they going to last more than that 10 years certainly the iridium satellite system went up from Motorola I think put it up and they never even put the full constellation of satellites up and then they went bust and now I can't remember what it's called now but the business of trying to run the satellite system for data is just the value's not there and now with the ubiquity of mobile phones most remote sites will have a satellite link to a local mobile tower and the people on site and the telemetry gear is all running over the satellite right alright thanks for that Steve what is the current level of interest from the community in tailings dam management good there is a broad interest and I think it varies depending on where you are at the international level you've got all sorts of different NGOs that have come together to create their safety first standard and that's been in response to the failures and so I think depending on what part of the world you're in there will be very significant interest and so I think and a lot of that will revolve around safety but also it's just around as we're talking about before the regulators, companies and things like that as well so there's certainly a lot of interest because it's people are concerned if things go wrong they can be very catastrophic and so we need to make sure that we are monitoring and managing our tailings dams in a way that we don't have accidents so hence the the name of the code or guideline for the NGO community is safety first it certainly seems to be growing I mean as you said there's more tailings and there's been some big failures so I think the public industry interests pretty high these days Dyke wall stability this is probably you Gavin initially well I think a lot of these things it's with the tailings dam you've got your dyke walls and things like that so you've got your internal structures inside a tailings dam as well as your main ring dykes and things like that so they can be quite important but it depends on how you're managing tailings, what the regulatory requirements will allow or not allow but again so all of those things need to be looked at it's but yeah I'm not quite sure exactly what else the questions getting out there but it's but certainly it's part of making sure we understand our the management of our tailings Steve did you have anything there? No All right well I think the next questions for you Steve. Yeah that's my baby vibrating wall I'm a big fan of vibrating wall it's such a simple technique and it's largely immune to cable length, immune to electrical noise and things like that so it provides a very stable long-term instrument and quite happily bury one of those and expect it to keep on working the technology is quite simple it's just basically a guitar string stretched between a diaphragm and the frame of the instrument and you're just measuring the frequency so there's no temperature effect on cable resistance or anything like that and I think they're perfect for this application Given all of that when wouldn't you use a VWP? You certainly wouldn't bury one for long term if it wasn't VWP on stuff that's a bit more accessible like moisture monitoring around tow drains you could put different technologies in and it comes down to price doesn't it if you want an instrument that's going to last a long time you might have to pay a little bit more one of the problems with vibrating wire is you actually need a specialised interface on your diaphragm to make use of it as opposed to something that's 4 to 20mA or voltage or something like that so it costs a little bit more, a bit harder to manage in that regard but it depends who's paying the bills they might have slightly different opinions that's always the problem isn't it? Generally Okay so that was a lot of early bird questions thanks very much for everyone who emailed those through now over to today's questions in the Q&A what is being done to remediate gold mining tailings? Hmm reprocessing them often and sometimes they're left there there's certainly if you're looking at western Australia there's been a rapid growth in the use of in pit tailings for the gold sector and there's certainly no shortage of pits in western Australia for gold so there's plenty of opportunity there but I think one of the problems and I think this is an issue that sort of popped up in a few of the different questions there and comments in the Q&A box is that a lot of gold mines will be put into care and maintenance maybe 5, 10 even 30 years later there will be more exploration work done and a new mine project put in place and so the old tailings dam becomes a new one and so I think that's often an approach you see so there are some sites where a tailings dam is actually formally remediated and rehabilitated so there's certainly some like that and Kidston's probably one of the examples that the industry used to love to promote but there's certainly different things out there but often I think there's still residual gold left in gold tailings and so often one of the best things we do to find a use for gold tailings is to reprocess it and then find it often in a different site for long-term storage. Okay thanks for that. Next question regarding legacy tailings dams I've been waiting every year to hear the tailings dam of the Rio Tinto Gove operation in Nellamby Northern Territory has collapsed. Unstable mountain of incredibly alkaline tailings next to a bay in a cyclone zone I suppose it hasn't collapsed but I'm sure how much you want to comment on that it's probably a bit tricky because it's a specific site. It's a site I mean I've never been there myself but I certainly have colleagues and friends that work there. It's an issue we know that red mud tailings has to be very carefully managed it's quite alkaline and so on so it's a problem we need to make sure I think we've got that transparency around and I think that's one of the key points hopefully I've been able to help justify is that rather than worrying about it potentially braiding all the time we should be in the opposite position where we can say yeah we have confidence that it's everything's in good order but I think that's the position we really should be aiming to get to and actually make sure we achieve. Yeah that's a good good claim for. Thanks for that. Next question we have new technology which could be especially useful on legacy dams but adoption of this technology appears to be slow what do you think can be done to help educate the market to prevent future catastrophic failures? Yeah it's a really good question and I think it's not just about the market I think it's also about the regulators but also about the community and I think a lot of it is understanding that that risk is there and so in parts of the land in South Africa the community are certainly very aware of their tailings dams and the issues going on whether it's water pollution from acid mine drainage whether it's the potential for failure so I think there's certainly it's a multifaceted sort of approach I think what you're looking at is that we need to educate the regulators companies often the consultants but we also need to work out how to fund it all I think that's one of the other problems that when you're dealing with legacy sites governments don't have much budget to apply to cleaning up or for remediating legacy sites so we need to come up with a system that allows us to come up with the funding process for that and there are examples the Northern Territory for example has a mining legacy fund and 1% levy is put on all operating mines and that goes into this mining legacy fund which they're using to clean up some of these old legacy sites now if that was adopted nationally we'd have hundreds of millions of dollars a year on which to go and clean up legacy sites so I think there are models out there and it's kind of the super fun type model I guess that used to operate in the US so I think that's part of the way we get that education out there it's got to be the regulators, the companies as well as working with communities as well but I think there's a range of solutions but it's a process not just a single point I guess super fun was certainly successful in driving remediation of polluted sites in the US that's a pretty well tested model next question G'day Gavin I'm all for transparency but how do you provide the data in large portions of the public are not literate in the technical aspects of these reports and studies how do you get the right level of transparency without creating unnecessary concerns for the public that aren't able to understand the data and terminology that's a good question Thanks Ben, it's great to cross paths again it's some I think it's the stuff we've always been doing we have really detailed technical reports and then there's summary reports or other approaches we can use as well but I remember being out at a tailing stand in New Zealand once where I was touring a particular mine with the community there and the company were being very open and the community asked me how would we know whether the company would whether there was an earthquake, whether this tailing stand would be safe and so I turned to the engineer and said well where's the monitoring data so I picked out the book showed me all the the piezos, the porpoises and where all the monitoring boards were and showed me where they've got their factor of safety analysis done and everything I said well there you go this is a pretty safe dam the manager was saying he wouldn't be worried about a tailing stand failure because he'd be more worried about the local gorge destroying the highway out of town which I thought was a rather odd response really so a tailing stand failure is significant regardless of what else happened so I think we have to address that concern and I think there is potential for that Ben and I don't think we can avoid that but we have to make sure that I think the reverse situation where we don't have information and there is that uncertainty that's a much worse situation to be in where I think you're creating a lot worse concern by having that uncertainty by not knowing so we do need to get better I think in making sure we translate what the data means and there's various ways to do that and I think there are some good models out there and the state of the environment style reports are one approach so it's an issue absolutely but I think we can address that but I think we have to address that and I think the position of saying well we don't have anything transparent and in the public realm I think only creates a lot worse uncertainty and therefore more concern so I think we have to do it and we have to work out how we get it right so that would be my approach hopefully that answers your question even it's interesting the use of the internet of things and the ability to in real time create virtual variables does provide the opportunity for very timely reporting of agreed metrics that would not have been possible like 10 years ago and could be published in a public domain so maybe part of the process which is a declaration of what the key indicators are and they can simplify the outputs like you say definitely I remember a really good example of something that's kind of similar there was an incinerator in Japan that was burning industrial waste and so they were always required to operate above 2000 degrees and the community understood that if you operated at a lower temperature than that you're at risk of forming dioxins and so the solution to that was a 36 foot neon sign at the front of the incinerator linked to a temperature gauge and so the company knew that if that temperature gauge, the display ever dropped below 2000 degrees they'd get a cavalcade of phone calls and it never did because they had that simple metric as you're saying and it was displayed publicly and so that way the public had confidence that everything was working properly so sometimes there may be some simple solutions like that and for an incinerator that one works well tailings dams are more complex but there's probably other ways we can deal with that. Thanks for that. Next question. Currently it is seen that various displacement rate alert levels low, medium, moderate are being proposed for INSAR tailings dams how could these displacement relationships be defined for each dam since it is observed that they are highly variable? Steve, you want to go to that one first? Yeah, I think you go for that. The movement at each dam is going to be very scientific so I think a lot of these things you can't just it's not a single quantitative number that we have to say is low, medium or moderate or extreme so and I think monitoring of things like earth movements whether it's in slope stability failures or things like that there's other examples where this sort of monitoring is being used but I guess for for tailings dams what we need to be able to work out is what's the significance with respect to failure risk or the impact downstream, they're the sort of questions I think we really need to focus on a lot of the alert levels or the risk assessment will have to be done at a site specific sort of basis so and I think that's why you'll see they're all highly variable but that would be my thoughts for the moment. Next question is from Dinesh. Have deep brooded tree stands been used to stabilise tailings dam slopes? Yes but do they actually work while variable? Sometimes I've seen examples where tree roots have actually helped destabilise walls and I've seen other times when they've clearly helped to stabilise them but again it also depends when we're talking physical stability to debate that Gavin, sorry the internet other times of course we're seeing issues with infiltration infiltration but it's tricky but yeah, you got an extra thoughts there Steve? I think what we've heard there is yet what trees have been used for location headings there's pros and cons I guess We seem to have a bad connection occurring we might move to the next question but I think the answer to that is yes sometimes Are IoT solutions such as Laura Wann preferred over traditional Cable sensor solutions is Laura cost competitive? Steve that's your question Yeah, I don't know if I can answer preferred just yet. There are some big advantages with low power long range wireless and there are some disadvantages to cabling in terms of cost it's quite cheap if you're paying $3 a metre for cable and running out a kilometre of cable you basically bought yourself a Laura station so I think as that technology becomes more accessible that it would start to take preference again we still have the long issue of if the technology changes can you still support it piece of wire is always a piece of wire but equipment manufactured by people who go out of business becomes unsupportable and that has to factor into your decision making process I guess the flip side of that is you could probably replace a fair few Laura Wann and then you could submit as before you got to the cost of the cabling with its installation so I think what we're seeing is yes we're starting to embrace more of those sorts of telemetric solutions and they're very promising and mines never close they go into care and maintenance just in case it becomes chemical to mine again there's a fair bit of truth in that what do you think Gavin? Yeah I think that comments I guess the next couple of comments they're all sort of very closely related so we're always backing up together but certainly if you look at the gold sector absolutely and there's extremely few mines we've actually closed and rehabilitated and then monitored for a long time so a lot of them do get closed and again so we're seeing that all over the place I guess so the question becomes especially the third question down about the regulation and modern territory as an example is how do we make sure we're still regulating these things to maintain the monitoring maintain the stability assessments so that we aren't leaving this liability for future generations or in case a company gets bankrupt and then of course government has to step in and fund that liability or pay for the cost of remediation etc so I think that's a really difficult question and I don't think any state's got a great solution to that yet I think the NT model as much as sometimes we often point to mines in the Northern Territory but the NT model of the mining legacy fund I think is a good one it's one that I think was bought in under significant opposition from industry governments of government in the Northern Territory but it was bought in for the right reasons and it's achieving the right outcomes and so I think there are models out there we need to make sure they're implemented much more consistently right across the board not just in the Northern Territory but also elsewhere okay so I think that covers a couple of those questions that are listed there so I might move there's a specific question about a supply I think we might skip over that one in terms of any conflicts of interest I must say I haven't come across those vibration monitors myself but I have done a bit of work on micro seismic monitoring and that was in a Long War coal mine and in the block caving setup where we were listening to the and calculating the amount of energy released by all the pops and the creeks as rock occurred I'm not sure how applicable it is to the soft material like tailings whether you would get any useful localization going on you might pick up ground movements in the wall I've had no experience with that I'm just wondering if they mean geocon vibrating wire piezometers but I'm not sure could also mean that sorry, although I reread it I mean geocon are one of the big supplies of these globally next question from Sudir, great presentation and very informative would you be able to share the short answer is you can share the presentations if you log into the Hydrotera website under training you'll find a full a list of all the webinars and their recordings so feel free to share that link with anyone that you like Pamela, what are the most used technique to create sites impacted by acid mine drainage goodness, that's a big question how long is a piece of string I'm very simply almost every technique you can think of sometimes using microbes other times using engineered soil covers water covers bulk soil I've seen like using red mud as a treatment method alkalinity from within that site what else I've seen, zero-valent permeable barriers or reactive barriers that are put in place pump and treat systems so I've seen lots of different techniques out there I guess what I haven't seen is a really good long-term monitoring of different sites that are affected by AMD to actually make sure we've got it under control and there are some, like certainly captain's flat out near Canberra is one that was remediated back about 45 or 50 years ago and the covers for there seem to be holding pretty well there's still a small tail of acid mine drainage there but it's certainly the Molongo River based on the monitoring and the reporting obscene of that some 30, 40 years afterwards it certainly seems to be in a reasonably good state so that small tail of acid mine drainage is certainly not causing as significant impacts ecologically so I think that to me is the big question there is like yes we know we've got to recognize how big the problem is and work out different ways to remediate the site but there are sites where we've got it really wrong like Rum Jungle and many others where the remediation hasn't worked that effectively and so I think that's the sort of one of the key things is we do the remediation but then we need the long-term monitoring and the transparency around reporting of what that monitoring is showing and I think that's a really important part of the process okay thanks for that so lucky last question for Nick Watkins and thanks very much to the speakers for hanging around for so long today how could the long-term impact of offsite contaminant transporting groundwater be best regulated? that's a big one with great difficulty it's a really tricky area because in a lot of ways most of our mines are not in areas where there's a local groundwater use there may be some but for the most part we're not dealing with mines that are next to large groundwater uses but a lot of them also we have to then think about in terms of offsite contaminant transport whether you've got surface water systems nearby there's mines I've been to where you've got salt lakes next door and so and you're dealing with salt lakes that are normally dry systems and now because of water associated from mining they're now permanently wet all the time and so sometimes there's all of these other questions that we need to think about as well in terms of contaminant transport and that groundwater surface water interaction so I think a lot of it is making sure that we ask that question and we do understand what the various risks are because they will be different in different parts so and then chose accordingly I guess but it's a really difficult one though because I think for the most part in Australia a lot of our mines are not near communities or near areas of large groundwater use so and that's why I think the problem largely gets swept under the aquifer swept under the aquifer it's the best I could come up with Richard it's a Friday afternoon. Alright well that's probably enough for the day thank you so much everybody for attending and great to see so many questions we've got over 21 questions there and well done to Gavin and Steve on answering those and if you want to look at the webinar again please feel free to log into our website and you will see all of the webinar recordings so thanks very much and see you next week thank you bye bye