 Well, hello everybody, and many thanks, a huge number of registrations for this particular webinar, the latest in Hydrotera's webinar series, this one on deep groundwater sampling, which is something that Hydrotera has had a lot of experience with. Next slide. Thanks, Kyle. So today we have Kyle McLaren, who's Hydrotera's product sales manager, presenting on various technology options and how they applied for the particular purpose of deep groundwater sampling. And you have myself talking about various methods for deep groundwater sampling. So Kyle will be focused more on the technology and I'll be focused more on the methods and some learnings from some pretty big projects we've worked on, which have required sampling from really deep depths. And in the background, we have Michelle Canton, who is looking after the webinar. So many thanks to the team. Okay, now this is a very important part of our webinars. We love getting lots of questions and we have a really good history of getting lots of questions. Just make sure that you do type them in to that Q&A section. It's great to get that and type those questions in and at the end I will read out those questions and Kyle and myself will then do our best to provide you with comprehensive answers to those. All right, so why does Hydrotera undertake these webinars? We like to generate awareness and share knowledge of the technologies and the methodologies that Hydrotera is developing or responsible for. And we really like to get that out to the broader community. So that's one of the key objectives. We also believe in facilitating training. I think training is an ongoing and really important part of what Hydrotera is about. And that is obviously part of this webinar. Lastly and most importantly, we like to get a better understanding of industry needs. Everyone has their own specific needs for environmental monitoring. And this is one mechanism for us to get a greater understanding from yourselves of these specific challenges that you're facing. Next slide, thanks, Kyle. All right, so in terms of the topic of deep groundwater sampling, I will be talking a bit about the methods and guidelines and some of the challenges around deep groundwater sampling. And Kyle's going to take over and run through various equipment technology options and considerations in putting together your sampling plans and equipment requirements for any particular job. We will then talk about a specific case study, which involved very deep groundwater sampling. Next slide, thanks, Kyle. All right, so into the guts of this. In Hydrotera's history, really our knowledge on deep groundwater sampling stemmed from two really large projects, which allowed us to spend a lot of time to research not only how to collect samples, but the various technologies that were out there. One of those projects was up in the Surat Basin, which was associated with Colson gas monitoring. Colson gas operations occur at depths of in excess of 800 metres. And part of the operation of those Colson gas fields involved monitoring the various aquifers adjacent to the gas bearing layers as well as monitoring the water levels within the gas bearing layers. So Colson gas involves depressurising the Colson gas formations, and that means gas is then generated and that they collect that gas. The concern, obviously, is if you're extracting that water and depressurising at a particular depth that you will impact on the aquifers either side of of that formation, which might affect other beneficial uses of those other formations. So I just put this schematic in on the right to show you a little bit about the challenges of this job. So there were several different geological formations. There was the Gubbaramanda formation, the Westbourne formation, Springbok formation, the Waloon coal measures, which were really the main formation of the gas in it. Then underneath that, the Urembar formation and the Hutton formation. Now, those formations had varying degrees of water in them and different hydraulic conditions. But the challenge of this job was how to collect a groundwater sample to look at the impacts on water quality that were occurring potentially associated with the Colson gas operation. Some of the things to think about there are which formation are you actually trying to collect those samples from? This particular schematic shows slotted casing. But in many of the holes, they were just open open hole below. So you'd have a steel casing at the top coming down a fairway. But then you just have an open hole section. So some of those sections of open hole were, you know, very long in themselves, 50 or 100 meters long of open holes. So even within the open hole section, which part of that did you want to sample? So there's various complexity around that. But I guess the main purpose of this schematic is to make you think about, well, when you're going deep, typically you are dealing with multiple layers of formation and you're also dealing with various issues such as off-gassing. So when you're doing this sort of thing, we were engaged to review the various sampling options that were available to collect samples from those sort of depths. The deepest depths were in excess of 1,000 meters below ground surface. And there are many things you need to consider in that. So the first thing we did was a big technology sort of review and developed a bit of a selection process around that out of all of that. Really, it boiled down to two groupings of technologies that we thought would be most applicable in that particular scenario. It's not to say they're applicable in all, but in that scenario. And they were dedicated pneumatic bladder pumps or double valve pumps. In the case of the bladder pumps, these are equipped with a drop tube assembly with or without a multi-port in-let assembly. Our drop tube assembly sits below your bladder pump and it's lowered down into the well and it has an inlet significantly deeper than where the pump itself is deployed. When you operate the pump, the water flows up the drop tube assembly. Kyle will talk more about the operation of those. One of the key considerations, though, is whether or not you're actually trying to collect constituents of the water, which dissolve gases. And if you are, then you need to take into account that those dissolved gases do start effervesce as you bring them to the surface. So you need to deal with the fact that whilst they may be dissolved at depth, by the time they're depressurizing, coming up your sampling, they start effervesce. And if you don't collect that gas, you've got a changed composition of your water. Therefore, you're no longer connecting something representative of what it's like at that depth. So quite a few challenges there. The second sorts of devices grab sampling devices. These can be mechanical or pneumatic. And Kyle is going to run through a couple of examples of those, including some new ones, some of which weren't even around at the time of this particular project we worked on. A real challenge with collecting grab samples at depth is those samples are collected from a zone of very high pressure. You know, they've got, say, 800 metres of head of water on them. That's a lot of pressure. When you bring those samples up to the surface, that sample is pressurized in that because these devices tend to be sealed. So when you get to the surface, you have a pressurized device, which has safety considerations and all sorts of things about it. So how you decant a sample out of a pressurized sampling device is not immaterial. Next slide, thanks, Kyle. So on this project, I just thought it was worth putting in here. This is a matrix which helped us to ultimately select and rank what was the best way to collect samples. Down the left hand column there, you'll see a bunch of different technology types like grab samplers, mechanical depth, specific samplers, etc. It just really shows you that there are a wealth of different ways to collect ground water samples. And then across the top with the site specific considerations, right? So what do we need to think about on our site when looking to choose the particular methodology to use? So just going across that top row, well construction is something that is very, very important. Often the diameter of your well is critical. Some of these sampling devices are quite wide in diameter. So you need to make sure, for example, it will actually fit down your well. You know, you might be sniggering, but that is often the case that people have got to site and found that they can't actually fit the device down the hole. Second thing is what they call headworks. So in the Colesham gas fields, the headworks on a number of wells were actually pretty complex. Some wells were artesian, so the headworks structures of your wells or the piece that's sitting at the ground surface, you need to be able to have an idea of that before you go out and sample. Sometimes the headworks is actually the headworks associated with an existing pump that might be down that well. That's particularly the case on farmers wells. So you need to know that before you start. Do you need to be monitoring level at the same time you're sampling? If the answer to that is yes, then you need to think carefully about how you're deploying your pumps to allow that to happen. If you're dedicating low flow pumps down a well, for example, then lowering a dip meter down next to that is something that's important, but it also instigates the potential for that device to get tangled in there. Some people dedicate pressure transducers next to the pumps they deploy, for example. It's really important to think about your monitoring frequency requirements. So that's typically stipulated in your monitoring plan. But if you need to monitor, you know, more than three or four times a year or even less when you're talking about really deep sampling, you're better off to dedicate these deep sampling devices because it takes a lot of time to deploy them. And there's a lot of risk when you're deploying for very deep sampling that you're going to tangle things up and potentially block a well. So you want to think about the risk reward there, the cost of dedicating a bladder pump or a double valve pump becomes immaterial in the context of having a blocked well. So in this particular study, we ended up recommending dedicated pumps in wells. And it's worth doing a sort of time and motion study to work out how long it's going to take to deploy the sampling, because sometimes just deploying the pump takes, you know, a couple of hours and your cost versus the cost of the pump when the payoff period is very quick. Aquifer considerations. Well, I mentioned that earlier, but one thing to really think hard about is if you're dealing with an open screened interval and you're lowering a low flow pump, there's plenty of works being done on stratification of water quality within open screen intervals. You need to think about your formation and the homogeneity of that and whether a low flow approach is appropriate, for example, or grab sampling for that matter. Sometimes you want to prevent connectivity between various zones and you can get various discs and things to put up above and below your sampling devices to effectively isolate zones to some degree. Depth and pressure considerations, well, absolutely critical. And, you know, standing water level in particular becomes very important in terms of choosing pneumatic devices, for example. Do you need to do conventional purging? So sometimes the requirements in your monitoring plan are driven by a legislative requirement. If conventional purging is required, then obviously you're not going to be selecting a low flow pump for that because it won't have the capacity to purge it. With these really deep wells, conventional purging is pretty impractical. The volumes of water you need to purge a one kilometre deep well, for example, just make it a pretty silly thing to consider. Is low flow sampling appropriate? That's sort of a bit of a double up with what I think about in terms of aquifer considerations. No purge or passive sampling is that appropriate? Sometimes it is. So you need to decide on that. Passive samplers are those sorts of samplers that you leave in place, come back, retrieve and they basically stay in the hole most of the time. They can be useful. They're no good for in general for if you're dealing with dissolved gases. Minimal water column disturbance, you can imagine if you're lowering a pump down eight hundred metres, there's a fair bit of mixing going on in your water column as you lower that pump down. That's one of the big considerations for whether or not to choose dedicating a pump in a well. Or going between wells using the same sampling set up as a general rule. I would recommend dedicating pumps when you have, you know, repeat sampling to be done. It's just removes a whole lot of errors associated with samples. Sample preparation, storage and handling. This really was very significant in this area because the sewer basin is a very isolated area. And just the holding times to get samples to the laboratory were extremely challenging. And the sampling times that we had using the low flow technologies meant that you may only be doing a couple of samples a day. And then you had to somehow get these samples to a lab that was often many hours away. So you really do need to think about what you're going to do to prepare, store and handle those samples with those logistical considerations. Water quality parameters. So we I presume most people on this webinar understand the importance of collecting field parameters. But a lot of sampling methods where you're using grab samples don't really allow you to get the intel that you get through a low flow sampling or continuous sampling approach where you have the opportunity to let those parameters stabilise. So that can be a really important factor. The next one, dissolve gas sampling. If you need to collect dissolved gas samples, that rules out a lot of sampling options. And it's really important to check your analyte list in that sort of instance. In trained or evolving gas sampling, that's really the end of dissolved gas sampling is when those gases partitioned, do you need to collect those gases that are partitioning? What I mean by partitioning, they're bubbles actually coming up your sampling line. So you're not getting a solid stream of water coming out of your pump anymore. You're getting a bit of a mixture of gas and water coming out. That can be very challenging. Lastly, the operation of maintenance. So here is it's really about, well, how long will it take you to collect that sample and what sort of maintenance is required around the system that you're setting up? So what I wanted to point out here is there's a lot of things to consider and it's not something to take lightly when you're doing those really deep sampling options. Next slide, thanks, Kyle. There's some guidance out there. Okay, you're probably going, gee, there's a lot to consider. Well, other people have done some of the considering for us. Some of these are the same guidelines that we would have showed you with just standard low flow sampling. The Geoscience Australia one does take into account sampling and how to collect gases that are coming out of waters. So it is particularly useful for those deeper groundwater sampling options. It's not to say the others aren't relevant, but Geoscience Australia publication does have additional information in it. Next slide. Thanks, Kyle. All right, so my last comment before handing over to Kyle is that deep groundwater sampling is not straightforward. So the two case studies that we talked a bit about today both had the need for a site-specific specification to be prepared to ensure adequate and appropriate materials were procured before undertaking sampling. That's really important with these bigger projects because the costs of what you're actually equipment, et cetera, it's really important to get your head around that at the time of quoting. The next one is around installation and sampling methodology. Significant time is required to install these things and significant time to sample. It's very easy to not include enough time for the sampling. One of two things happens in that sort of scenario. You're either collecting samples inappropriately because you're trying to collect them too quickly or you end up underquoting the job because you haven't allowed sufficient time. So it's really important to understand how much time it's going to take to actually do these things. Now installation normally you can get a pretty good, safe number, but the actual sampling side of things, if you're sampling from 800 meters depth, it takes four hours sometimes to collect a single sample. So you need to be very careful in how you estimate those times. Now Hydrotera does a lot of this sort of work and we're happy to work with consultants and obviously industry with some guidance on that or to assist on various projects. Now over to Kyle who's going to talk in more depth about the technologies and how we've applied them. Thanks Richard. Good afternoon everybody or good morning depending on where you are and thanks for joining us. The ways in which we would be able to obtain a sample from depth is quite wide and the technologies and offerings out there in the market can be almost daunting with how much is out there. We see a few examples here of some of the technologies from simple balers, point source balers, grab samplers, passive samplers in the diffusion bags, hydro sleeves, gas-driven pumps, a lot of the things that Richard was talking about in that previous schematic. And if we go through each method and technology we'd be here for a very long time. But given the vast and various ways to sample a lot of the times the preferred method to obtain the best representative samples of the aquifer is attempting to conduct low flow or in some instances grab sampling from the screen of deep bores and often times the technologies that allow us to perform this in your standard 50mm bores gives us a bit of a size restriction as well. So it's often the main scenario that we see most of the time and this leads us to a couple of pieces of kit and considerations which will be our main focus today. So what are the methods that we typically select or what I see. So Richard did speak just briefly on the bladder pump with the drop tube assembly. Our main bladder pump that we deal with obviously is the 407 bladder pump. So we're utilising basically a 1.6 inch pump with the drop tube set up. The important part with this is that generally with the bladder pumps we have a maximum operation limit and in the case of the 407 this is 150 metres below ground level. So the reason for the drop tube is that our pump can be placed higher and the drop tube wherever you'd like basically for less pressure requirements. Our bladders that are available in the bladder pumps LDPE, PTFE for longer term deployments. When we're dealing with those higher pressures we might see if we elect to sit the pump in between that sort of 100 metre to 150 metre mark which we tend to see on standing water levels with very deep bores. Generally recommend sort of the Teflon bladder if you can given the higher pressure ratings. Typically sometimes this can be a method that people elect to use just from the preventative of contact of air supply with the sample water and the operation with the bladder pumps. Some people prefer as it's less fine tuning. However we'll talk a bit more in depth in a minute in the installation sort of considerations when looking to go with the drop tube assembly. The maximum flow rates approximately 1.5 around about 2 litres a minute in these bladder pumps. And the ability to dedicate as well for the 407 also. I've seen that a lot with our clients that they do often with the deeper stuff want to dedicate these drop tubes with the bladder pumps. But also as we also said and Richard mentioned that our choice for preferred deep groundwater pump is the Solance double valve for 408. Important that we sort of address a couple of things here on this one in that. Compression fittings used for deep applications. Recently Solance have elected a standard to have the connections on the pump as barb fittings. That's okay with sort of your normal depth sampling our requirements. We've been fortunate enough to have the ability to still order these pumps with the compression fittings as they were a while back which is what we recommend if you're looking to deal with deeper applications on this. So just a little bit around the theory I suppose on these double valve pumps that allow us to be able to sample from such a depth. With the 407s or any bladder pump you're actually calculating PSI pressures based on the pump intake given that there's a bladder there. So that has its limitations. They're in electing without a drop tube. But in the case of the double valve if we have the ability to have our standing water level in our bores less than 150 metres theoretically we can place this pump wherever we like the pump intake. It comes more into play I guess around the installation requirements when we're going a bit deeper which I'll talk about in a minute. But the quick theory on these pumps is that the valves inside the pump allow that water to come back up the drive line to standing water level and then we're simply applying drive gas on that column of water in that drive tube down to create that loop which pushes the sample line up to get our samples. So we're using a little less pressures when we're just calculating it standing water level that way. So we do see some higher flow rates that we can achieve with the double valve pump which is another reason why we sort of elect this way. We tend to see that we sort of get a little bit less of a sample and takes a little bit longer in the 407 with the drop tube assembly aspect. As I said, yeah, less PSI pressure required as calculations work on standing water level. So there's a lot of considerations really that we've learned over the time and a lot of clients that I've spoken with and what we have experienced out in the field ourselves for the deep groundwater sampling. So key factors and probably just to reiterate a few points that Richard might have mentioned earlier but these points I guess I'll go into a bit more detail in a minute but probably the first one, initial sounding of the well, it sounds pretty basic but it's very important obviously for obvious reasons. We want to make sure that there's not a breakage 200 metres down before we even start placing the pump. So very important, the weights if you set up buoyancy issues with your weight, the tubing considerations is there drop tube needed? Another point that Richard made was allowance of time for proper installation per well. Obviously the last thing we want to do is have a pump stuck at 600 metres and it's probably a thing that snags a lot of clients in is the allowance of time for the proper installation of these and taking your time with it very slowly to be able to install these pumps at the depth, you'd rather take your time than have it stuck. So that's an important one. Your designs of your well caps Richard did mention about the off-gassing which we'll talk a little bit in a second and of course coming back to that allowance of time dedicated verse portable setups. So when we're talking about sampling depth considerations just around the specs I suppose of those pumps and what I was talking about earlier. So again we're calculating pressure requirements depending on the standing water level if we elect to go with the double valve. So that allows a lot of flexibility there to be able to put it wherever we like really and we'll talk about a case study shortly about how deep we've actually gone with these specific pumps and then for this reason the tangles of the pumps during deployment with tubing, cable, etc. There's a lot of stuff going down there especially if you have additional things down your hole. So for this reason what I was talking about with allowance of time is that it should be undertaken very slowly to install your pumps. We can use manual reels if you think about our installation at depths of 800, 900 sometimes even a kilometer down we're utilizing some pretty heavy gear at the top with manual cranks that sort of thing to let our wire down slowly and just allow to give us the best possible chance to not get any blockages. So one thing I talk about a lot with clients looking to do deep groundwater sampling is the buoyancy considerations. So around about the 300 meters of merchants depth we start to see the buoyancy and the tubing coming to effect. So actually the tubing will have enough buoyancy in it to start to cause the pump to come back up on itself around the 300 meter mark. So that obviously opens up a lot of things in terms of potentially getting stuck. So it's important to have enough weight on the bottom of the pump to all drop tubes to allow for a straighter tube rolling. A couple of examples there is the double valve pump on the left. We had a custom milled that's just a milled stainless steel spike which is a solid piece which just is for the sheer purpose of weight down there just to give us enough weight to put that pump down where we needed it to be for the buoyancy issues. If people wanted to elect to go with the drop tube I have seen in other instances with that picture on the right just as a little example some short pieces of thick stainless steel pipe or even like discs on the end of the drop tube threaded through that half inch tubing just to allow that extra weight and the reason why we have short pieces along the length of it is just to allow us to have that flexibility in the tubing to potentially snake down the hole if we have really long pieces and that's something that occurred with the picture on the left is that that was probably a little bit too long that spike and was causing a little bit of difficulty in that but just to allow us to have that flexibility in the drop tube to still snake down the hole and not cause any rigid areas with long pieces of pipe so considerable amount of weight just consider your weight requirements when you're dealing depending on how deep you're going but obviously we can talk through that in more detail if you need more guidance on that the tubing considerations so your pressure and burst pressure of your tubing so this is an important one that I talk about a lot with people around again that 300 metre mark you know LDP is considered suitable by many operators and it's for general sampling that is fine, it is okay but there's probably consideration to switch to HDPE if we're dealing with really deep stuff so it can be a little bit harder to work with but when we've got really long pieces of tubing taking hundreds of metres there's a stretching that can occur along the length and it actually compresses the diameter inside the tubing which puts a bit of strain on our upstream controls and pressure and that sort of thing to allow us to get enough through that tubing so that stretching actually reduces the diameter internally of that tubing and can cause a bit of strain so by having that extra rigidity in the HDPE it's allowed us to overcome a few things and that's what we utilise in the case study we'll talk about later in some cases Teflon Codile DPE tubing can be used as it's just less prone to contamination from organic compounds that sort of thing but there's also the cost consideration on that because Teflon tubing is quite expensive but just a point to make there and food grade or similarly tested material should be used when possible to minimise false positives so coming back again I guess in that weight consideration when we're talking about pump suspension so there is a risk of pump detachment at the tubing connectors which is why we recommend having those compression fittings on that tubing I have seen in the past that people install these dedicated pumps just on the tubing and compression fittings themselves I always recommend to have a suspension anchor particularly with the deeper stuff as you can imagine we might have additional weight at the bottom of that pump as well to overcome some buoyancy issues so just allowing having an allowance on those compression fittings themselves on the tubing is just simply not enough we need to utilise that suspension anchor that's on the pump to avoid that coming off and probably one to mention is that if you can imagine we're dealing with hundreds of metres of cabling if we elect to go the stainless steel cable just your weight considerations on that can be incredibly heavy and so for the really deep stuff that we did we elected to go with the Kevlar line on there just to reduce some of the weight in the setup so important to consider that so just a bit more detail on the drop tubes deploying the drop tubes can be problematic they are prone to tangling in the bores and that's probably the biggest one to underline there in that the installation requirements of having the drop tube probably the one thing that comes undone with our selection versus a double valve and a drop tube assembly we have a weight at the bottom we have a large piece a long piece of half inch tubing and then we have another weight in the pump body itself and then more tubing in that twin bonded so it just opens up more room for that drop tube assembly there's not enough weight there to come back up on that half inch tubing and start to tangle as we keep lowering that pump body down to where we need it to be and that can just cause can cause tangles and that tended to occur a lot with some people trying to install those so it's really important that if we elect that again it comes back to that time allowance when you're doing your installations with those pumps you can take your time with it if you want to elect to go with a drop tube but again that's why we recommend having the double valves because your entirety of your weight is at the very bottom and you're only dealing with twin bonded tubing all the way down instead of thicker half inch tubing which has more potential to be wrapped up in it so just consider that your buoyancy restrictions as well and also you're just a little bit of decrease in weight between the two so Richard did mention about the off-gassing considerations on this as we move from high pressures in very deep wells up to lower pressures we bring the sample up and we can potentially see some off-gassing occur in waters containing dissolved gas and ourselves and Geoscience Australia have developed some methods to enable us to sort of sample those off-gasses which we'll talk about in a minute just on a case study there but Richard did mention a bit of that before so we'll move on now your well cap considerations as well probably just another point that I wanted to mention in this is generally we utilise the dedicated silenced well cap just with the 50mm casings with the safety hook and push fittings on the bottom there in that lower right hand picture there are several well cap options on the market and there is compatibility with the pumps that you elect versus the well caps that you might utilise along with the controllers that you might utilise to get your desired pressures when doing your sampling it's probably just important to mention that most of the pumps have cross compatibility with whatever well cap you elect generally there's just going to be some tubing push fittings at the bottom there to connect into it and then your head works at the top of that cap would probably be compatible with whatever controller you want to elect so for well casings that are greater than 50mm a couple of options you can either go a customised sort of well cap that you drill yourself which is in that picture there up on the left or we go to reducer couplings over the top of the casing to put it back to that 50mm capacity to then allow us to use the dedicated caps so just a couple of considerations in regards to the well cap and just your air supply options just a couple of points I suppose when dealing with the higher pressures required for the sampling we just recommend having really high rated PSI controllers and compressed gas that sounds simple but it just allows us flexibility on site to be able to increase pressure as if needed sometimes people will try and spec to meet getting lower rated controllers or something like that and it's just important to just have that allowance when you're dealing with upper echelons of some potentially lower PSI rated controllers you just run the risk of some maintenance requirements there through that so important to spec highly on the PSI ratings and recommended with the compressors I've been asked that quite a bit around using compressors for general low flow sampling they're okay however with really high pressures we always recommend bottled gas to do that sort of operation of the compressor trying to maintain a pressure in its chamber while you're utilizing it if you needed to go compressors you have to then look at exploring options with that sort of dive rated compressor that allows you to have quite high pressures and they can be quite expensive if we go to the lower rated compressors there's just a risk of burning them out because if we're dealing with higher pressures we can maintain a pressure within the chamber so there's just that risk there and generally with the compressed gas side of things CO2 and nitrogen are the ones we typically use with the really deep stuff we tend to get higher pressure ratings with nitrogen but I can explore that with you and talk that through if you need just before the case study is an interesting one that is released which is the 425 deep discreet sampler this is the piece of kit that Richard said has been released prior to us doing all that sampling which would have been handy to have but I just thought it was an interesting piece of kit to add here so now I have capability to take a discreet sample up to 1200 meters down utilizing this slightly adjusted discreet sampler that's going on an internal piston system overcoming hydrostatic pressure at those depths that you're looking to sample at so again that also has the options to then start adding weights to the bottom to overcome that buoyancy issue on there so this is a new piece of kit and we're looking to explore as well and we'll get one and test it and we'll be happy to talk through some potential on how that could potentially work with your applications also so just at the end here was the case study so we undertook some groundwater and dissolved gas sampling on behalf of DPI in the Gippsland and Otway basins for Victorian water science studies and we sampled some bores there that were in excess of 1200 meters in depth so obviously as Richard and myself have been talking about that sort of proved some very high challenges there in terms of how we sample to that depth and we developed and reviewed some SOPs and source custom equipment in order to conduct the sampling at those depths required and the sampling of the dissolved gas as it was depressurized was sort of monitored through a water gas separator as you can see in the right image there a GA and the gas was actually collected through sewer mechanisms used to sample from the custom well head so that schematic on the on the top there was a bit of a breakdown with the various different ways and you can sort of see the complexity in how to actually sample from those depths when we bring it up and the challenges with having that depressurized gas coming up through the separator and how we go about actually obtaining those samples so that was a very interesting case study on there but before we go to any questions Richard I was just wondering if you had anything else to add in terms of this case study also No Kyle I think you've covered it all pretty well I might just emphasise a couple of things here so the challenge with the selection of tubing is and the expansion that you mentioned is when you're under deploying at great depths choosing to use HDPE is better because it's a harder material and it actually expands less which means you when you're rising from the surface you don't lose as much pressure when you're on your drive cycle so it actually holds firm if you can imagine across a length of a kilometre a little expansion in tubing across a whole kilometre adds up to a lot which can be a lot of volume of air to deliver to try and push that sample up it's important that you do consider HDPE for those deeper samples so just clarifying a little bit there the second one is with the the things that I guess the learning from these sorts of projects are drop tube assemblies whilst they sound attractive are actually the source of quite a few blocked holes out there but the tubing does end up wrapping around your pump like Kyle mentioned before so when we're doing this we typically have the double valve pump at the end of the tubing and with weights on that double valve pump just to avoid the potential for that jamming of the wells because it does happen right it's a reality and then maybe the last sometimes you can have descriptions of wells which aren't actually accurate in terms of their diameters so things like often you'll have say a stainless steel screen down the well which may be a different diameter to the PVC casing for example and that can lead to problems where if you've got relatively low tolerances between the diameter of your pump and of the screen you can end up with that pump getting stuck in the screen interval so definitely worth learning about that but this project was a fantastic project it involved sampling something like 70 wells and it was a good example of us collaborating with Jacobs to deliver that data for ultimately a statewide assessment of the groundwater and the dissolved gases within it so at that time Kyle I think we might head over to the Q&A yeah we'll start to see what we have coming through we have a few questions I'll just go through the chat area first just to see if there's anything Andrew Davidson removing the pumps and tubing can be problematic the tubing can be electrostatically attracted to the sides of the bore that's interesting that's an interesting point there and temperature depth is also an important consideration for tubing yes that's a good point and thanks Elizabeth Elizabeth Stanmore said thank you keep going with the webinar series it's great thank you for the feedback there Elizabeth so in terms of some questions we've got a couple anonymous what depth is it generally accepted that a program is considered deep water sampling versus a depth which uses conventional standard monitoring methods I could probably answer that one yeah yeah I'm in normally where you've got a standing water level that is getting towards the limit of deploying a pump without a drop tube assembly I suppose so you're operating depth in maximum operating depth of say a solence ladder pump is about 150 meters so when you're so when you're deploying or needing to deploy at that sort of depth below ground surface I would consider that as being deep would be the way I would view that yeah yeah I think that's true I guess it's just the when we start to look at the specs of an operation of the equipment being utilized and when we have to go think about going above those specs on standard standard operation principles I think is probably when we start to look at considering a deep water sampling and utilization of drop tubes and everything to take that screen past you probably you might be utilizing it you might be utilizing drop tubes before you even get to 150 meters if you're looking to just not having to use that much PSI pressure but there's considerations based on the specs of the equipment and if there's potential if you're looking at a particular program where you're sort of thinking it might be on the cusp between standard equipment and whether you need to make a few adjustments based on this webinar we're happy to chat through with you so Kelvin Baldock come through saying question one to ensure isolation of sampling pump to the target zone packages above and below the pump position are deployed yes so Solans to have got what we call straddle packets which allow you to inflate packers either side of your inlet of your pump to isolate a zone the challenge is to make sure that the packers expect for the particular setting that you're looking at them to perform at but the short answer is yes there's also other devices that are sometimes used which are a bit of a sort of compromise but still considered significant some times I've seen plastic discs used which are either side of the pump at either end and it sounds like a plastic disc but it actually does significantly restrict the vertical movement of the water column therefore you're at least getting a much higher level of confidence that the water you're sampling is coming in laterally from your screen and from your formation so obviously that's a key assumption of low flow sampling that you are getting water coming in from the aquifer not just coming from either side of your inlet within your well so short answer yes on that one yeah and the question too for Calvin is has sampling for stygophonar or toglophonar ever been part of the specifications for sampling analysis in the projects in our projects yes so we have actually on that case that I spoke to at the Surat base in stygophonar was was a target and I would need to go back to my notes so Kel it's a while ago to look at what the sampling devices we used for that from recollection we did all of that sampling separate to the actual you know devices that we're talking about here today so you can't use your obviously your double valve pumps and that sort of thing to collect stygophonar you needed separate sampling devices which I think were like little nets from memory but I need to check my notes so maybe I'll take that one I notice and come back to you but certainly was a key factor excellent Prachi is there any contamination from the tubing that you need to worry about do you want me to answer that one Kyle yeah sure so there's quite a few studies of different sorts of tubing out there there's studies on contaminants that come out of the plasticis that are used into the water and there's studies on the absorption of contaminants that are in your water into those plastics so there's two potential problems one is that you're getting contamination that's being absorbed to your sample line and then potentially impacting other samples you might be collecting so if you're moving between wells that becomes a real problem if you're reusing the sampling materials like the tubing but the second factor is you can have effectively some contaminants absorbed to that and then effectively moving back into the water column later on and therefore you might have some difference between the composition of what your sampling versus what the actual condition is at some point in time so there's absorption of the contaminants and most of the issues that used to be associated with early problems with choice of plastics and them contaminating water have now sort of been put to rest if you look back 25 years ago there was a whole lot of papers written about such things and a lot of it related to well materials like gasing materials and that sort of thing but now it's pretty well accepted if you're choosing food grade LDPE that you're in pretty reasonable shape or food grade HDPE you know that's sort of become reasonably well accepted I hope you can answer the question Yeah excellent Anonymous again just saying which products are available for long-term monitoring in deep aquifers greater than 250 meters e.g. vented or non-vented water quality probes I'd probably say there is a few options out there if it came up non-anonymous I'd ask if you wanted to contact me through those details on the screen there we'll be able to talk through those types of equipment that you might be looking for there certainly are a couple of options that you might be able to look at for there so feel free to shoot me an email Andrew Davidson is the case study in New South Wales of Victoria Victoria Victoria was that that case study that we explored before the other one was in Queensland the other one was in Queensland I can quite remember where that one was I think that's everything that we've answered so far but that's given us a good allowance of time for today so we might wrap it up there but thanks everybody for joining us today excellent turnout and really appreciate all your all your time to listen to us talk about the groundwater sampling so feel free to contact myself or Richard if you have any other further questions outside of this but from myself and from Richard we thank you very much for taking the time today to listen to us thanks very much everybody thanks very much Carl well done thanks Richard