 Welcome all. I'll just leave another 30 seconds just for everyone to join and then we'll get started. A few participants there now. Thank you for joining us here for another of the HydroTera webinar series for 2021. Thank you all very much for taking the time with us today. For those of you who are new to our webinars throughout this year will be continuing with a series of presentations about Fortnightly and look to share our knowledge with you all as much as possible. These will be a mixture of method and theory and also product focus. So be sure to be able to look out for presentations that you may be interested in. And for today we're looking into a bit of our learnings and knowledge around low flow groundwater sampling. So today we're joined by our managing director, HydroTera Richard Campbell, who will kick us off around the theory associated with low flow sampling and some considerations prior to doing so. My name is Kai McLaren. I'm the sales manager here at HydroTera. And Michelle, who is our webinar organizer, will make sure that it all goes well and hopefully the trend of it all running smoothly continues. So thanks for joining us today guys. As many of you may be familiar with now the way we run these sessions is that throughout the presentation. Please feel free to write any questions you may have in the QA box at the top. I'll collate these and we'll also allow some time at the end of the presentation for Richard and myself to answer as best we can. If we do go significantly over time and can't get through them all. I'll make sure to contact you with some answers and also happy to discuss with anybody after the session any of the things we speak about today. Our objectives are always to generate awareness of the methodologies and technologies and develop along with you. The knowledge of options to consider in this case when we do our low flow sampling. Educate as best we can for the appropriate adoption of technologies in your future projects and understand from you your needs. I've heard a lot of tricky scenarios in the time that I've been here with my clients around groundwater sampling. But the beauty of this is that there's always something new. And if we can assist in providing options for your unique projects, that's something me and the team really get a kick out of. So a quick overview of the run sheet for today. Richard will kick us off with some theoretical considerations of low flow sampling, some guidance resources and addressing challenges prior to conducting. And then I'll be taking over for the remainder to talk about the basic operation principles of the sampling pumps that we generally deal with here in HydroTerror. When doing our low flow sampling and also some considerations around each of the technologies that you may be looking at to do the low flow sampling. As well as some frequently asked questions that I've sort of collated over the time that I've been dealing with the clients and the groundwater sampling. What I most commonly receive and looking to my thoughts on those for those frequently asked questions and a bit of a discussion piece there. But without further ado, I'd like to hand over to Richard at this point in time. So thanks Richard, if you could please take it away. Thanks very much, Kyle. So I guess the presentation today is going to draw a bit upon my previous work experience in consulting. Also in auditing where I had to review data collected from low flow. And then some of the projects that we've conducted at HydroTerror where we've had to undertake low flow sampling, but in more extreme environments than would typically be undertaken. So I think there's some valuable learnings to share there too. So what's the actual real objective of low flow sampling? The end of the day, we are trying to collect the groundwater sample of quality and what does that mean? Well, it needs to be representative of the aquifer that we are trying to collect that sample from. And whilst that sounds straightforward, often we're in a hurry and low flow becomes rushed low flow, for example. And we start to compromise our samples. So a big and important part of this is to realise that low flow sampling does need to be taken in a patient way to make sure we are meeting the requirements and the assumptions that sit behind it. There's a really good publication which is EPA Publication 669 which outlines some of the theoretical considerations and the operational considerations. That's a Victorian EPA publication. If you're not familiar with it, I suggest you jot that down and have a read because it's a very good document. Next slide, thanks, Tom. So there's a few references. The first one is the one I just mentioned. There's others out there and there will be more than these, no doubt. The one I typically use most is that first one. If you're looking more at how to actually think of considerations around a broader hydrogeological assessment, then the second one there is useful. There's a little bit of a crossover between those two documents, but the first one is most relevant to today's discussions. If you're looking at considerations around things like preservation times and that sort of thing associated with the samples once collected, EPA Publication 441 is useful in that context. And the Geoscience Australia document is actually a pretty good document where you're looking at doing low flow sampling where you tend to have off-gassing samples. So a lot of those guidance documents were developed at the time that coal seam gas industry was trying to work out how to monitor their groundwater quality. And a lot of the contaminants of interest were gaseous and at significant depth. So as you bring those samples up to the surface, they start to off-gas, and then it's pretty hard, isn't it? You've got a sample that's a mixture of gas and water, and it actually does. We call it FFS, but it starts to bubble and you're at the top of a narrow piece of sampling tube and you're getting a mixed flow of these things. So working out what the water quality is like a depth in the scenario where the water quality is actually changing within your sampling apparatus as you bring it up a tube is challenging. So there's various methods around that that we have worked on in the past. So there's some publications that I'd suggest if you're interested, have a read. The top one is probably a must-do check if you're doing low flow sampling to give yourself good context. Thanks, Kyle. On to the next one. Okay, so the principle behind low flow is that the water that's in the aquifer adjacent to your well is the water that you're sampling into your low flow equipment. Now, the reality is that that's a bit of a reach, right? It's an assumption that is hard to prove. It's an assumption that is fundamental to this technology. But if you think about it from a practical context, it's easier for the water to flow up the well from underneath the inlet point or down from above because there's no resistance to flow. It's not like it's passing through a sandy matrix or anything. So we need to have various lines of evidence to convince ourselves that the water we are actually sampling isn't coming from the stagnant part of the well above us. It is, in fact, coming from the aquifer. And so the lines of evidence that we use are monitoring the disturbance of the water level in the well as we undertake this pumping. Now, we call this drawdown, right? It's drawing down the level of water in a well. The rate we pump affects how far we draw down the water in the well. The amount we draw it down is a function of the actual hydraulic conductivity of the aquifer itself. So hydraulic conductivity is the ability for water to pass through the aquifer. And depending on the type of aquifer that varies quite a bit. Sands have a high hydraulic conductivity, clays have a low. So if you're trying to pump in a well screened in a clay for the same pumping rate as in a sand, you will see a much higher drawdown level. Auditors in the like worry about drawdown because it affects the assumptions that are behind low flow sampling. So one of the lines of evidence that people look at when they're deciding whether or not the assessment work you've done is suitable is drawdown. So they like to see data on that. And that's typically collected with something like a water level meter. Or if you want to do it continuously, you can use a pressure transducer, which can be deployed down the hole. So there's a few ways to measure water level, but it's a very important metric to have. The second main one is you can use water quality parameters. And so in the guidance documents, you'll find a lot of discussion around stabilization of water quality parameters. The assumption here is that if you're seeing stable measurements of parameters like pH electrical conductivity and those sorts of things, that that indicates the water that's coming in is coming in from a constant source. And if you've got that data plus the data from your water level meter, you can say, okay, that constancy of data suggests it's coming from the aquifer. And that's a really important set of data as well that you need to collect. So there's a couple of important assumptions that sit behind this. So low flow perging relies on the concept that groundwater moves horizontally through the screened interval in a bore. So there's an assumption that it's not mixing with that water I mentioned before from above your screen. So really for this to work, we need to assume that the water within the screened interval of your well is of the same quality as the water in the aquifer itself. And we need to assume that when we're pumping, because we've got the inlet of our pump placed within that screened interval, we're pumping water that's coming from the aquifer. Okay, so what are the steps we need to go through? Well, the first one is we need to lower our pump pretty gently. We don't want to make this well or turbulent. We don't want to have water from above the well screen getting pushed down into the well screen area. So we lower it slowly and carefully. And we like to place that inlet roughly in the middle of the screen. Why would we want to put it there? Well, the reality is that's the furthest point from where it might be stagnant and being affected by things like the air above the water. So within your well, if you think about it, the surface of the water in your well is exposed to the atmosphere. So there's chemical reactions going on there and there's off-gassing and that sort of thing. So concentrations of various parameters as you get nearer that air-water interface change. And they're not representative of the aquifers. So you want to get your pump inlet down where it's most likely to be representative of the aquifer. Obviously, when you lower a pump down in a well, it causes some problems, right? It causes the mixing of the water above it. It pushes some down. So if you're in a situation where you're doing a long-term low-flow sampling program, like on a mine site, for example, or on a long-term contaminated facility, then dedicating low-flow pumps, that means you leave them there for good, right, is a much better way to go than using portable ones and decontaminating them between holes. Not just because of the potential for you to bring contamination from one well to another, but because of that disturbance of the water, pushing that water down into your screened interval can cause errors. On a practical consideration, a lot of the low-flow pumps have these little ball valves in the bottom. And if you place a pump too near the bottom, you can end up with sediments getting in there. And that not only causes more sediment in your sample, but it can also affect the function of a lot of pumps. So high-spumps don't like sediments. Next slide, thanks, Con. All right, so a couple of factors to think about if you're planning a low-flow sampling program. Well, some of these things happen well and truly before you even start sampling. And one of the big ones is drilling. How has that well been installed? Has it been developed? And what do we mean by developed? It's really removing any residual sediment that's in your well. If you come along and do low-flow sampling and have well hasn't been properly developed, then you will have residual in there, and that will affect your samples. It also depends on the type of well. So I've listed a few there. So there's drive points, which I've got a picture of later where you just built them into the ground. There's multi-levels, where you have multiple screens within wells within the one location. And then you have your standard monitoring wells. And they all need to be considered because certain pumps don't work in certain types. So you need to know what you're going to be sampling from. I have seen situations where people have gone to site and need to discover they can't fit their pumps in the wells. I've mentioned board development, so I'll move past that. Before you go, you need to really know your depth, the screen interval, because you need to be able to lower your pump to that desired depth. You also need to be able to know for sure whether or not you've got a pump that can have the capacity to lift that water out. Often Hydrotera works with really deep wells, you know, long way down. Some of the wells we've sampled have screen intervals more than a kilometre below ground surface, right? This photo we're looking at here with this gas separator with the orange shirt. Alex used to work with us. He is sampling from a well, which is very deep, and we've got off-gassing concerns around that. So there's all sorts of considerations as you start dealing with deeper samples. That picture of a pump second from the left is a converted double valve pump where the bottom section of that is just a solid stainless steel weight. So the whole thing, just to give you some kind of scale, is about a metre and a half long, and that weight is heavy. It's solid stainless steel. And the idea of that is you need to overcome buoyancy effects when you're sampling from a long way below ground surface. So in this particular project, we had lots of wells where the standing water level was quite shallow, like maybe less than 50 metres below ground surface. But the screened interval where we needed to collect the sample from was over a kilometre. So you had all this tubing that came down above those pumps, which caused buoyancy effects. So we couldn't get the pumps down without putting those big stainless steel spikes on the end of it. Contaminant type is important. You really need to know before you go what the contaminants are because there's a misconception about low flow sampling that it's about the pump type. It's not. It's about the pump rate. So you can use all sorts of different pumps to collect the low flow sample as long as you can reduce the pumping rate to a slow rate. So you can use like a 12 volt electrical pump as long as you can get the rate down far enough. But it depends a bit on the contaminant type to which pump you should select for your low flow sampling. And I have a table I'll show you in a minute which provides a bit of guidance on that. Other decisions we need to make, right? Well, I've said the first one, pump selection. The second one is to whether or not to dedicate or do portable ones. That involves a cost analysis as well as considerations on data quality. As I said before, dedicated systems always provide better data because there's less variables. You need to work out how much tubing you need, how many bottles, that sort of thing. And what sort of tubing, right? So LDP is fine up to a certain depth. But when you're dealing with these really deep samples, the tubing flexes too much and it takes too much gas to get a sample up. You're literally creating a bigger volume as you pressurize the system. So in those instances, we use HDPE, which is a more rigid tubing. You need to know about your decontamination procedures. And we have standard operating procedures for that. Most of the companies you work for would also have their own SOPs. So I won't talk too much about that other than to say it's obviously very important that you do decontaminate. Sample preservation, you can put a lot of work into collecting samples, but if you aren't preserving them in the appropriate way, which is in one of those references I mentioned earlier, or your laboratory often tells you, then you can have significant changes in your water quality of your samples before you get them analyzed. So you've got to be careful with that. So really, these photos, I've talked about a couple of those. The one on the left though, that system on the top there is a gas water separator. So in that particular project where we're collecting these low flow samples, which we're effervescing, and we had a chamber which partitioned the gas from the water. A water sample was collected into a bottle, and a gas sample was collected into a tedlar bag, and we did a back calculation on the concentrations in the gas to work out what the total concentrations would be in the water. I will, and that's Kyle. Is that you, Kyle? That is Kyle on the right there doing some sampling. So Kyle can talk more about that particular project. I wasn't involved directly with that one. Now, next slide please, Kyle. Okay, so in terms of monitoring wells, just to recap a little bit on some of the things I've said. So we want to have our sample coming into that well-screened interval, which is that slotted section that you'll see in this picture. So we need to know what the depth is of that well-screened before we go out, right? And that should be marked on the well-construction records. Sometimes people go out and they think I'll just sample, and I've seen this, right? When I sample, when I hit my water, I'll go about a metre below it and that'll all be okay. Well, I've worked on systems where the inlet there is more than a kilometre, or that water level is more than a kilometre from where your slotted screen section is. So what happens in those scenarios, and I have seen projects done like this, people have gone and sampled not from the screen and have all done a complete sampling round and the data's been deemed not representative. It's very important to do that. Next thing to look at is just the actual well-construction. So you'll see the sort of gravel depicted of the filter pack. The filter pack's important. It's effectively part of your screen, right? The screen refers to the slots in the PVC, but when you start pumping, that filter pack is of a much higher conductivity typically than the aquifer. So water will flow from that filter pack as well. So sometimes people construct wells badly and you have a very long filter pack, and that can lead to problems, particularly if that goes up above the boundary of the aquifer. I'm able to talk more about that another time, but we're going to run out of time otherwise, so I will move on, but just a couple of practical considerations there. Next slide, thanks, Colin. This is a drive point pesometer. You would use these sorts of things, particularly in areas where it's difficult to get access for a drill rig, or if you're doing a very short-term low-flow sampling exercise where the depth of water is less than about sort of three metres maximum, even three metres is quite a long way down with this technology. The reason I wanted to show this was you'll see the tube poking out the top of this. Well, the only way you can really sample a low-flow sample from this sort of drive point is using the peristaltic pump, which is a, you can see it on the ground there to, well, to the right of that operator as he's facing us, but left of the image. So drive points are a useful way in combination with a peristaltic pump of collecting low-flow samples in shallow systems. Next slide, thanks, Colin. Multi-levels can be used to collect low-flow samples as well. Now, multi-levels are used a lot, quite a lot these days, because this continuous multi-channel tubing is the CMT and rarely used these water-lose systems on the left. So I'll talk more about the continuous multi-channel tubing. That picture is pretty much to scale. So each one of those little sections of that tube is effectively its own monitoring well and you have a well-screen that's constructed into those tubes. So you can monitor from multiple aquifers from the one well by using each discrete tube to monitor a separate aquifer. You never cut one tube into two aquifers because you'd be breaching and causing connectivity between those. So always cut one into that. The reason I wanted to talk about this with respect to low-flow is there are these little dedicated low-flow pumps that you can fit in those tubes. So you can conduct low-flow sampling from these and you can set up manifolds to allow you to collect low-flow samples from multiple tubes at the same time. Next slide, thanks, Colin. Okay, so last slide for me. This is a useful table that's in that EPA Publication 668. And in there, they have recommendations on sampling devices, but this also covers your low-flow pumps. So you'll see down that left-hand column a number of different pump types, like peristaltic pump, gas lift pumps, for example. What I typically use this for is to give you a gut feel of how the regulator feels about such things and what sort of pumps one should be using for certain types of parameters. So you'll see across the third row from the top is a list of parameters, and then you'll see that they have a coding for whether or not a certain device is suitable. Now, I don't agree with all of what's on here, but it gives you a snapshot of what the regulator felt quite a few years ago now, but it is good guidance and a good point of reference for yourselves. Now, I think a better hand over to Kyle to continue forward. He's going to talk more about the specifics of various pump types and how to utilize in low-flow sampling. So over to you, Kyle. Thanks for that, Richard. Yeah, it's good in-depth detail there on the theories behind that. I'll start some things off with a bit of a chart here. I'll start to delve a bit more into the operation principles of the most common things that we deal with and also just some considerations for equipment selection when you are out in the field and just some things to be wary of in my experience that I've had so far with groundwater sampling. So here is a list of basically the most common pumps that we deal with at HydroTerror. We can issue a copy of these slides to participants here today if you wish to delve a bit more into these charts. But the main pumps that we deal with here at HydroTerror when looking at low-flow sampling is the QED sample pro, which a lot of you majority would be familiar with. Great portability and ease of bladder changes for easy de-contamination and really the main pump of choice in OZ for the more shallower sampling, so less than sort of 50 metres on paper. It has some sampling of up to about 70. I've found, in my experience, I tend to struggle to get significant flow rates past the sort of 55 to 60 metre range. So it's just something to keep in mind. And then we have the Solance range of pumps, so the 407 bladder and the 408 double valve, which I'm going to talk a bit more in depth in the next slides. There's also the micro double valve pump for those CMT systems that Richard mentioned earlier, the multi-level systems and of course the peri-pump, which we've also spoke about. The 12-volt pumps, which some clients use more so on the purging method of sampling, but the low-flow controllers that do associate with some of those pumps do allow for that control being able to utilise the low-flow method. And just something to consider of doing a sampling round where you have a bit time constrained and you need an economically viable option quite quick. There's still some considerations with these, but I'll talk about that shortly. So the 407 bladder pump, I'm just going to talk about the operation principle and this does apply with the exception of a few specification differences to the QED sample pro as well. So the principle of drawing in water from the pump intake into our bladder during vent cycle and a drive cycle, which is us applying our compressed gas or air, allows us to compress the bladder inward to draw water up a sample line. It does prevent contact with air supply to the sample water and there is less fine-tuning involved when wanting to select the bladder pump for these operations. We have a maximum depth range on these pumps at about 150 metres in the 407 bladder pump. And again, compare this to the QED, which is about 60 metres in my experience. So if a bladder pump is a method of choice that you may be sampling or you've selected to do your low-flow sampling, if there's instances where it's a bit deep-up, then the specs of the QED sample pro, the 407 may be something to consider as well. And there's the option of a drop tube assembly with these bladder pumps to change the screen pump intake to deeper depths while still utilising our calculated PSI pressures and drive and vents for where the body of the pump is sitting. So there's also options for dedication of these pumps, which Richard did speak about earlier. The 408 double-valve pump operates without the use of a bladder and work on the principle of applying our drive gas to the column water that comes back up to equilibrium with the standing water level. So that's the main difference. When we're doing our calculations between these two pumps in consideration, in the bladder pumps, both the QED and the Silent 407 and basically any bladder pump, we're doing our PSI calculations with the pump intake of where the pump is actually sitting with the double-valve pump that allows us more flexibility because we're doing our calculations based on the standing water level. So the operation inside that pump allows for that water to come back up the driveline into standing water level so we don't have to apply as much gas. So we can say that if we have standing water levels of less than 150 metres below ground level, theoretically pump anywhere. And in the case that Richard mentioned earlier, we have done so with these pumps to over a kilometre deep. There is a bit more fine-tuning process to avoid air contact with water if that's something that really needs to occur in your site. But if the PSI drive and vent calculations are utilised, this process can be easily overcome, which is the calculations I'll talk about in just a second. There isn't a need for a drop tube assembly and you can sit the pump anywhere, again provided our standing water levels are less than 150 metres and also have an option to dedicate these systems to which we have done so for numerous sites around Australia with these double-valve pumps. So this is just a cross-comparison of the two pumps side by side and below us some quick sort of calculations when looking at our PSI drive and vent times. These are a good starting point. I have covered this a lot more in-depth in detail in another webinar that I've done previously, which is directly comparing the 407 and 408. But it's really good to hit home these calculation principles because it is a very good starting point for your low-flow sampling when considering and going out into the field to do so. There's a document that I've put together and I can provide, which is a bit of a cheat sheet on these calculations for anybody that may be interested also. And the calculations for the bladder pump also apply to the QED should be mentioned as well. So for calculating our PSI for the bladder pump, this can be both, as I said, for the 407 or the QED. We calculate based on where the screen intake is, as I mentioned earlier. But I want to place my pump somewhere in the middle of the screen. And we use our calculation, which is actually taken from Solace, where they say that one PSI can lift about 2.3 foot of water. So I take my depth in meters and there's a couple of ways you can do this calculation. But I times that by 3.3 to convert that to feet. I then divide that by that 2.3. So the 2.3 foot of water per PSI. And then I add plus 10 to account for what they call line loss. So you will get some bleed from your tubing and your connections and your pumps and that sort of thing. So this plus 10 PSI does account for that. And conversely with the 408 double valve pump, it's the same calculation, but we're working this out again just at the standing water level initially and not from the pump intake. You can do this at the pump intake for the double valve pump if you wish to increase your, get that sort of low flow purging levels happening. But generally for our, in the case of our low flow sampling, we're just calculating at the standing water level initially. And these PSI are calcs are a good starting point to come at with whatever bore you're coming up. So I take a look at my bore logs. I have my screened interval. I've got my meter edge of where I want to sit my pump. Once I have that, I'll be able to use these calculation to see how much PSI I'm going to need prior to even going out in the field. So for the drive time, you can apply in the 407 bladder pumps and for the QED bladder pumps, you can apply manually your air or gas to the pump and you can place your sample line at the top of your bore into a submerged bucket of water. When you apply your drive gas, you should see bubbles being expelled from this sample line, which indicates to me that the bladder is being compressed and the air in the water is traveling up that sample line. So when the bubbles stop, that indicates to me that that bladder is fully compressed and we want to be at 80% of that time as a good starting point for a drive cycle. So 100% of that time means that the bladder is being fully compressed all the way down. There's no more. It's only a set volume of water in that bladder. So we won't see any more coming out until we do another drive and then another vent and then our next drive cycle. So about 80% of that time, that's where that calculation comes from. 408 is a little bit tricky and a little bit harder to get your head around, but you can place the pump initially. You can time your manually applied gas the same as with your 407s, or your QEDs, whatever bladder pump. And effectively, we want to wait until our sample line expels all the water from the drive line and again it comes back up to standing water level in that drive line all the way down through the pump and up through the sample line where you'll get an expulsion of your compressed air-compressed gas. And this happens initially when you place the pump. So again, if you're worried about your air contact with your water, just remembering before we even take our water samples, we are ensuring that we're purging enough water to get our equilibrium in our parameters to come through. So hopefully that process will avoid that. So if we consider that time that we've timed to get all that water from the drive line through the pump up the sample line to be 100% of the time, we want to be up 40% of that time will be a good starting point for a drive cycle. That is a bit tricky to consider, but basically if you cut the pump in half, essentially you have 50% of time on each side. So we want to avoid that air contact with water. So we're saying 40% of that time will allow the air to go down the drive line and then when we reach event cycle and we'll come back up to equilibrium and back to the standing water level and then we'll repeat that process again. So if done correctly, you won't have air contact with your sample water. But these calculations can be a bit of a guide for you and I can talk more in depth about that if you have more questions regarding that. We're calculating our vent times. We say that it's definitely based on your bore and your hydraulic conductivity and your recovery and your draw down when you're doing these samples. So as a basic principle, I always say at least twice to three times your drive time because again when we're driving that's when we're drawing water from the aquifer and that vent time allows that water to recover. So that's where we're closely monitoring our draw down level with our water level meter and the vent just allow is just our bore recovery time. So we want to have a good amount of time for that bore to recover and you can adjust that to be increased more it might need more recovery if it's a slow recharging bore or it might need less if it's a rapidly recharging bore. So once you calculate your PSI once you calculate your drive times and you give it a vent time of least twice then there's the some basic starting points for when you come across to any bore really. The maximum depth ranges are situated there and then your drive and sample lines probably just one quick thing to mention is that on the QED and the 407 bladder pump you have a quarter inch with our twin bonded tubing your quarter inches the air the three eighth is the sample the only difference is in the 408 out of the box the three eighth is the air and the quarter is the sample. This can be changed and we always recommend to change over and it's a quick process just to change those fittings around using less PSI pressures with a smaller diameter tubing in that quarter inch and so I always swap those connections over but that's just something to consider if you do have double valve pumps that are looking at those for future projects. So by utilizing those basic calculations that I said it provides us with more details prior to the sampling to ensure that we have the right tools for the job. So if I look at my bore logs and I can do my PSI calculations based on what pump I'm using prior to even going out I can ensure that my controllers my compressors my regulators are going to be enough for the job to occur. So in the case of the science controller if I take a look at my bore logs and I'm on the cusp of my 120 PSI range I may want to consider going to that 250 PSI range just to give myself a bit of a buffer if the site is quite remote and I just want to ensure that for whatever reason if I'm not getting a bit of a sample I might need to bump up my PSI a bit more but my pre-calculations are right on that cusp that's the things to consider there. So those calculators give you a bit more of an insight before you even get out to site what you might need in terms of your gear to spec you know what to do your low flow sampling. So the compressed air I've used the example here of the 12 volt compressor from Silenced but it's a very viable and portable option. More shallower applications I would say the compressor is better to utilise so I generally say if you have bores that are greater than about 40 metres and you have quite a few of them just some things to consider the compressor is the operation of it. So the operation of the compressor is that it's trying to maintain a constant pressure inside the chamber of the compressor. So if you have quite deep bores and you're using quite high PSIs with quite multiple bores there's a chance that you might burn out those compressors whichever one it may be. So if you're on a remote site and you're wanting to utilise a compressor it's just something to keep in mind that you might want to consider going back up there of some compressed gas and a regulator prior to going out to site but that's just something to consider there. In the case of the compressed gas we generally utilise CO2 but nitrogen is also an option sometimes CO2 might not be viable for some VOCs that are of concern on the site if you're worried about that gas contact with your sample water so some people might typically shift to a nitrogen and generally you will find that if you're sampling quite deep nitrogen might be your gas of choice because we tend to get a few slightly higher PSI ranges with nitrogen, gas and regulators. It also can be tricky to make sure that your regulators for these are also capable of handling enough PSI pressures and they are often difficult to find but if you are struggling with that I can certainly assist if you're struggling to find a regulator that is fit for purpose. I'll just breeze quickly over these other options that Rich has already spoken about the parasolid pumps just a couple of things on paper, 10 metres based on sea level because it's a vacuum pump I generally find that 6 to 7 metres lift is about where you start to get more of a trickle so just consider that sometimes whilst it's on paper that says 10 metres generally we're never going to be directly level on sea level or below sea level so just keep that in mind there. They are reversible with those controllers so for shallow board development like those little pyzos that Richard mentioned earlier that is the little nifty thing to keep in mind and great portability for a site to when access might be quite difficult so you're taking your portable paysometers and your parasolid pump and you can get some samples that way. I mentioned earlier the 12 volt submersible pumps as I said they are small diameter options in 12 volt you can achieve good depths with them so something like a stainless steel monsoon can give you about 50 metres of lift the low flow control that gives you that control to be able to still do a low flow sample but some considerations for this is that there is a high potential for burnout of lift running continuously I generally find more than an hour or two hours there can be some problems with those they highly turbid water can be problematic for these pumps as well so if you're no prior to going outside that you have quite a high turbidity in your water that might be something to consider if you're already looking at the 12 volt submersible pumps but they are economically viable for a short sampling round so there's just some things to keep in mind with the submersible pumps there and just quickly mentioned I guess the foot valves whilst the principle of these might not necessarily be low flow and the definition of these guys are based on the diameter of the foot valve correlating to whether it's a standard or a high or a low flow it's just something to keep in mind if you have a very tricky scenario where you have very small diameters or a bore that might be semi blocked and we can't get anything else down there to get a sample foot valves might be something that you could consider and there are sort of mechanical actuators with those that you could utilise with those foot valves is it necessarily a low flow sample well point of contention but are you getting a sample with it in those tricky scenarios just something to keep in mind there with that and finally I'll just brief over I suppose some frequently asked questions before we get into any questions that you guys might have so some touch points I've already spoken about here but the frequently asked questions that I get almost on the daily would be when would I use a QED versus a 407 bladder pump well you have those depth restrictions that I spoke about before with those that's probably the main one you also have your timing in terms of your bladder changes with the 407 bladder pump that can be a little bit longer than the QED sample pro so you might want to weigh up those considerations but generally if you have greater depths than the QED can handle but you still want to go for that bladder pump option then the 407 might be something to consider there I did touch on bottle gas versus compressor air previously in that slide but again your bottle gas you're going to get higher PSI pressures than your compressors your compressors have a potential to burn out if you have high utilization on those and you're also limited to your PSI ranges with your compressors you can use higher spec compressors for sure it doesn't really matter what compressor you do use you can change your fittings in those compressors to directly connect to any controller you have but just to consider that if you're operating these with multiple bores at quite deep depths that's something that can happen what if I've got a less than 50mm bore well there are quite a few options for this those 407s and 408 pumps that I spoke about can be in a lot smaller diameters than your general 1.66 inch so there is a 5 eighth inch double valve pump there's a 1 inch bladder pump there's those foot valves that I spoke about to give you a sample there's a lot of different ways to obtain a sample when you have a lot less than 50mm diameter bore the 408 and 407 I did touch on previously PFAS sampling are there options? yes it is tricky as we probably all know it is quite a point of contention coming in in Australia certainly some things that I would consider when you have a site that is potentially PFAS contaminated and that is an area of concern from the client your materials when going to do the sampling obviously we know your HDPE over LDPE needs to happen anything that you can change for stainless steel for example in some of these pumps generally they're Teflon balls but we can have stainless steel check balls implemented in and also to consider your statements from your suppliers sometimes your statements from your suppliers in terms of the PFAS side of things they are happy to provide but the statement will generally always say that there is no known PFAS with known being the key word there that's something that people can give and that's fine because they're never going to sort of state unless there is laboratory testing that there is no PFAS in the equipment that we provide sometimes that's okay for orders sometimes that's not so there is some more options around the PFAS stuff that I'm happy to deal with there's also considerations with your decontamination for example DECON90 is not suitable for PFAS when decontamination you need something like a liquid ox or something like that that is okay to to DECON your your equipment but happy to discuss this if anyone else is looking at a site that might be PFAS contaminated and happy to provide some guidance on that after this low flow versus purging method is something I get asked to be quite a lot the purging method where we take our three ball volumes might take a bit more time than our low flow sampling we also have to consider is the site maybe a bit sensitive on where we you know expel that purge water from if we over pump we're starting to draw down past that screen into the sump level which we get increased turbidity coming through that might affect our overall water quality for our metals that sort of thing purging method might be the method of choice both are acceptable in the guidelines low flow is our preferred method but certainly it's not to discredit purging method at all there's a lot more depth and detail that we can go into after the fact but that is a question I get asked quite a lot and we did cover a lot of things that Richard spoke about in terms of sampling quite deep some things to consider that was your HDPE tubing as opposed to your LDPE tubing apologies and also your depth and weight on the pumps when you get a buoyancy issue past your sort of 300, 350 meter mark you need some significant weight on the end of your pumps and there's just some things that we can speak about if sampling from deep is something that you're looking into we've certainly done a lot of that so happy to provide any guidance through to you if need be but I think that's enough from me thank you all I will take just a little bit of time now we have gone a little bit over so apologies for people but thanks for sticking around and we'll filter some questions that you might have so if you want to take this time to share any questions that you might have we can maybe answer a couple but if you push for time please feel free to reach out to us and we'll be able to answer thank you Nicholas thanks for attending the average lifespan of the QED pump Julie it's a tricky one it also depends on your utilization of that pump and where you're utilizing it they tend to we have quite a large fleet in our rental fleet of the QED pumps and they last for quite a long time the lifespan of it is definitely a grey area where we're looking about where have you utilized and highly turbid areas have you used it in aggressive mediums that type of thing but certainly it's a highly reliable pump that has quite a long life if cared for properly definitely unless we yes we can provide you the copy of those slides no problem at all waters of QED pump in waters of EC yes that's okay that's generally okay it's about half of sea water so the 316 stainless that's okay to be utilized for pumping I would just a good cleaning process after the fact if you're doing portable sampling would be key there and a good decon of everything after you do it but I've done so in higher EC ranges from a portable system aggressive your mediums are also important to consider prior to you wanting to dedicate systems as well so it's important to take a look over to those if dedication to pumps is something you might be looking at because that's when obviously you have the pumps being constantly in that water some high EC that type of thing just some things to look at but we're happy to provide your guidance on that if that's something you're interested in just checking both avenues of the questions here thanks Liam thank you for joining us thanks Graeme no problems at all look we've taken up Hang on sorry Julie's supply as mentioned plastic tubing for QED pump is once off use seems wasteful, can you recommend if tubing can be used more than once yeah that's also a common question that I get Julie in that is is tubing able to be reused it is able to be if decontaminated properly and can you guarantee that you're decontaminating that prior before you go to each and every bore the way that you would have to decontaminate that is to you know have a have a drum of water that's decon and have that pump running through the cycle of the entirety of that tubing to be able to effectively decontaminate prior to going to each and every site so whilst it may seem wasteful there's also time considerations with this in terms of reusing tubing but something to keep in mind in terms of the wastefulness is that we often try to go with biodegradable tubing and that's an important process for us as well to have we generally don't go with anything else that's not biodegradable just as a bit of an offset for that wastefulness on the tubing so there's a way up there in terms of the time investment to decontaminate that tubing if you wish to do the sampling process as per the guidelines as best you can with how much tubing you're using and are you decontaminating it properly so that's probably some things for you to consider there in terms of reusing tubing. Me personally I wouldn't I just think a setup that you have to take to properly decontaminate to run a cycle of water all the way through with decon through the entirety of the tubing if you have quite a deep bore that might be quite a long length might outweigh the cost of the tubing and if we go with biodegradable that's less I suppose less for our conscience on that hopefully that answers your question there Julie thanks Santo on joining us I'm glad you can make it so if there's no other questions there our contact details are there for myself and Richard thanks Hips Richard for joining me today on this and providing your knowledge on the theory associated with the low sampling and obviously if there's any other questions or any other discussions you may wish to have please feel free to reach out to us either by email or the phone number below but thank you all have a good rest of your day and hopefully talk to you soon thank you