 Well, thanks, everyone, for joining us today at HydroTerror's latest webinar. Today we're looking at all things about monitoring wells, leachate sumps and gas wells in and around landfills. We're fortunate to be joined by Pete McCurry, who's Director from Matrix Drilling, who's got a wide range of experience in the actual application of this topic. Before we go too far, I'd just like to acknowledge, whoops, I've snuck past that slide. I'd like to acknowledge the traditional owners and custodians of the land on which we meet today, the Bunarong people of the Kulin Nation. I also pay my respects to their elders, past and present. There's a picture of our friend Pete McCurry, a little bit about Pete. So Pete's a hydrogeologist by training, and he studied both at Monash University and in Canada. And he worked in predominantly contaminated land for around 10 years, I think it was with coffee mainly, undertaking site investigation and remediation projects on petroleum and industrial sites across Australia, before taking a leap of faith and starting Matrix Drilling in 2008. Pete's proud to now say they're operating 10 rigs across Australia, which is obviously a major investment and a great achievement. Matrix specializes in the provision of safe, high quality, and reliable geotechnical and environmental drilling services to the site investigation and resource drilling sectors. I think it's important to acknowledge the wisdom that one can gain from drillers on site. Now, often the engineering scientists and engineers miss the opportunity of really picking up on the things that the drillers do know. So when you're working with them on site, my experience is they typically know more than most people about how to do the drilling, how to install these things. So that was the real driver for getting Pete involved today was there is a lot of wisdom and a lot of knowledge in how to deploy these things that we should all know about. Before we charge into the actual webinar, just we love your questions and it's a really important part of these webinars. So to raise a question, just use the Q&A button at the top of your screen and type that in and I will read out the answers to that at the end of Pete's presentation. Why does Hydrotera undertake these webinars? Well, we like to share knowledge and we feel that there's a real need to be facilitating that at the moment in the industry. We like to facilitate education and we like to be an industry leader. So bringing knowledge into the industry that's going to help us all to move forward. All right, without further ado, I'd like to pass over to Pete who's going to talk to us about digging deep, discovering the secrets of monitoring wells, leachate sumps and gas wells in and around landfills. Over to you, Pete. Thanks, Richard. Thanks everybody for joining. It's an absolute pleasure. Hats off to Hydrotera, Richard and your team for releasing this together. It's fantastic. I, as Richard said, I'm a former consultant turned drilling operator. I would say I'm a much of a driller employee drillers to do the tough work. There is a fair bit of wisdom. I think that was a pretty nice depiction that Richard gave of drillers, not something that they hear very often that they're wise, but I think they are as well with all of the things they need to do. I wanted to give just an overview, I guess, of drilling methodologies and some of them will be relevant, more relevant to landfill drilling than others. But I think the interesting thing is with a landfill site is that you're dealing with waste, a waste mass, but you're also looking at the surrounding site as well. So there's conventional drilling that's an important part of site assessments on landfill. So I will cover off on some of those methodologies, but I'll sort of make the main focus will be on landfill mass drilling. So might go to the next slide. Richard, if that's all right. Thank you. So the purpose of drilling at landfills is probably where we should start. Often, we get asked to come out and drill a bunch of holes on landfills to determine the extent of a landfill, whether that's vertical or the lateral extent. And in some instances that can be on the landfill occupied land, or you might end up in suburban streets drilling holes in people's backyards chasing landfill gas and things like that, which is obviously a pretty concerning thing for residents and whatnot. So it's not just on the landfill itself that we find ourselves. And most commonly, we'll be drilling to collect representative samples of soil and rock. So the cap of the landfill and the surrounds, obviously the waste material itself, groundwater in the surrounding areas and below the landfill mass, and then lead chate and gas within and obviously hopefully not on the outside. But quite often it is found on the outside. And then obviously the selection of drilling methodologies is really important for getting good accurate samples at the end of the day. When we install a well and we do it properly and do it with the right techniques and install the right materials and constructions and often we'll get good results and representative samples. Some of the things that we need to consider prior to getting out to site are things like is the landfill operating or is it a closed site? That's more a health and safety issue for us. So if it's an operating site, you quite often have dump trucks and various bulldozers and things moving around. So that's in and of itself a risk. But if you've got friable material and asbestos, especially kicking around, people driving around site and just causing all sorts of inhalation issues. So that's of interest to us. The waste type is obviously really interesting for us to know. So is it municipal waste or is it construction rubble that's going to obviously determine the type of drilling that we are likely to do? The surrounding geology is really important as well. So just around Melbourne, we have such a variety of former quarries and existing quarries and landfills. So in areas like Footscray, we've got Quarry Park, which is a former Basalt quarry. And it's surrounded obviously by a pretty massive Basalt, same as out in Coburg, around the prison out there. And then out in Franburne, you would have like a sand quarry where, say, like the Cranburne Botanical Gardens are and then dotted all around the place. But Gronswijk and out east Oakley, you've got your clay quarries. So knowing that's really important when you're looking at drilling in the surrounds. And also knowing whether there's a confining layer or a seal at the bottom of the landfill is really important to know. Like, is there a liner? Because if we're punching down through that, we're obviously potentially going to contaminate the groundwater resource for lots. That's a pretty interesting thing for us to know as well. So I'm going to touch on the drilling techniques. I'm not going to spend a lot of time on conventional techniques. But just in terms of what we do and what most other drillers do, so looking at auger drilling, direct push, rotary air. We use compressed air as the essentially the drilling fluid to remove cuttings and to cut the rock. Diamond core drilling, wash boring. And then you get into the, I guess, more unconventional drilling techniques. So sonic and bucket auger. And one that I haven't listed there is cable tool, which is probably one of the oldest drilling techniques. No, I think it was invented some 5,000 years ago in China. It's still quite relevant today in some instances. So this slide, just in terms of selection of drilling, this is a table that we send out to our clients just to give a bit more information on what they should expect and how to go about choosing your drilling technique. But probably the important thing here is to look at geology and consider that when considering a methodology. And the two main things to look at are unconsolidated and consolidated geologies. And in the sense of land from mass, obviously you're looking at unconsolidated. But then to dig a little bit deeper into that, it's really important to know whether that material is likely to stay open once you've drilled it and pulled your tooling out. Or whether it's going to collapse. And typically, we find that landfill mass, especially municipal waste, will collapse. Building rubble is the same. So the risks there, I guess, are using particular methods, which if there is collapse, you can actually get tooling stuck in the ground, which is expensive for everybody involved. But also just the idea of installing instrumentation for monitoring in any type of bore or well, you obviously have to have an open hole. So whether it's collapsing or staying open will determine whether you need to case that hole off or whether you can install into an open hole. I might go to the next slide and just go through some of these drilling methodologies, Richard. So I guess a common drilling methodology is solid auger. What have you seen that before? Just that helical flights surrounding a solid stem rod, which as you rotate just like a drill bit on your hand drill, it'll just cut and bring the material to the surface. You probably have to flick through these reasonably quickly. So that's an example of sand coming up. But in that instance, in that photo there, that sand would probably stay open down to the water table. Once you get to the water table, like if you're digging a hole at the beach, once you find water, it just starts to collapse. So trying to get an installation in through a solid auger is pretty challenging in those kinds of materials. So then you look at hollow augers, which is essentially the same idea, except it's got a hollow pipe and these come in various sizes. So you can install different size installations, maybe 50 mil or 100 mil into it. The drillers would typically get pretty upset if they know that they have to use hollow augers because they're really, really heavy by themselves. And then once you take those in mud and clays and whatnot, they just become really unenjoyable to work with. So if you see a nasty look on your drillers face, anytime that we need to switch to hollows, that's usually why, because it just makes their day a bit harder. Direct push is more of a soil sampling methodology generally, but there's a couple of different types. So there's a single tube, so like a macro core, which you drive down, pull your sample out. And in doing so, you have to pull the entire drill string out. And if it's collapsing formation, you'll just have a clutched hole. But there's also a dual tube, which allows you to case ahead. So once you pull your sample out, you go back down and continue to drill. And the idea behind that is that you get in-situ samples. You don't have collapsing material and re-sample that same formation. But it also allows you, particularly with the four and a half inch tooling, allows you to install wells. And so quite often we'll install prepacked wells into four and a half inch dual tube. Downhole hammer is a pretty common one. So using compressed air and a reciprocated hammer, so with rotation, and it's great in consolidated formations. It's no good in landfills because of the, I guess, the varying levels of compaction, building rubble, potentially falling in on the back of the hammer. It's really easy to lose a hammer in that kind of type of drilling. So we're still clear of that as well. Diamond core, again, are quite good for the surrounds of a landfill, not really any good on the inside. So you might just step past that one. You might want to just mention that using diamond core is great for if you're looking at identifying, you know, preferential flow paths in bedrock and that sort of thing. So sometimes it's good to get that detail because you are getting truly a solid core out that can be interpreted. Yeah, that's right. So yeah, you can look at fractures and fracture sets. And yeah, you can throw a flute liner down a diamond core hole and get ideas of Dean up with contamination and separate fracture sets. It is good for that. Wash boring is not a bad option because if a hole is staying open, obviously you can just, you know, use drilling fluid. So quite often we add things like bentonite or polymer to hold a hole open to form a wall cake in the case of bentonite. Not great in landfill mass, again, because of the lack of compaction, you just lose your water forever filling up and using more and more attitudes. So it's not great, but you can run a casing with that and have a casing advance, which allows you to do case ahead of the whole if you want to put installation in. So again, a conventional method, not really well suited to landfill mass. You end up with a big annulus around the outside of the casing with that technique or is it sort of tight fit to the casing? It's typically kept to the case, to the bit size, especially if you're using a heavy mud or like a heavy bentonite mud, you'll form a wall cake. And so if you're in a sand, for example, you'll be able to hold a bore hole open for a reasonable amount of time to allow for an installation. It's a really common method for groundwater well resource pours. But yeah, in landfill, just because of the lack of compaction and loss of water, it just becomes not really ideal. But do you use it commonly for resource wells, but not for observation wells? That's right, yeah. So the previous methodologies I would consider conventional and we'll move into the non-conventional drilling techniques. Sonic being probably the most common now and to really take the industry by storm. There just seems to be more and more Sonic rigs out there. I guess the premise, there was a figure on that slide that's not showing that essentially showing that how the head works. So it really is just like a rotary rig, but you've got a set of oscillating weights inside the head and they oscillated a frequency that can be manipulated to the resonant frequency of the material you're drilling through. It's pretty amazing what it does. It essentially fluidizes the substrate that you're going through and you can change that as the substrate changes. So in landfill, for example, you can just get, you can do like a three meter or six meter run in a matter of a second, a minute. It typically uses water. It doesn't have to use water, but some people would consider it a bit of a silver bullet and I'd say maybe in landfills and tailings down and things like that. They're right. It's not always the answer, but it's a really amazing system and it runs like a casing and sampling system. So you would, for example, run a six inch casing and have a four inch sample barrel collecting sample for analysis. And you've got a cased hole the entire way down. So it's really, really good for landfill type situations. The water is really just to cool the bit so you don't need to recirculate typically, but if it does recirculate, it's captured and sent back down. But it really is becoming the methodology of choice at landfill sites. And that's our, yeah, sorry. With the sample that's retrieved, is that coming up as a like a solid core or is it coming up sort of messed up core? It comes out very much in situ. So it's almost like a direct, it's like a big, direct push sample. If you're drilling through rock, the vibration can sometimes shut up the rock. So if you're looking at it from a geotechnical point of view, or if you're looking for fracture sets, it can sometimes affect the outcome of that type of analysis. But in terms of sampling waste material or any sort of unconsolidated material, it's, yeah, it's as good as anything out there or better than anything out there. And that rig there, that's our little LS250, I'll say little, it's the biggest rig that we've got, but that's a baby compared to the larger sonics that are out there. But it's a small footprint that gets out into some pretty tight spots. So that's been a good one for us. When wouldn't you use Sonic? Say again, sorry. When wouldn't it be appropriate to use Sonic? So with a smaller Sonic like ours, we typically don't run in massive basalt. We'd use it in sedimentary rock quite often, metamorphic rock, anything that's, it's quite hard. Our Sonic would probably start to struggle after a few meters. But if you put, so ours is a 75 Hertz, if you put 150 Hertz machine on there, so say Southwestern drilling, we've got a couple of the bigger ones. If you put one of Berkey's Sonic rigs out on pretty much anywhere in Melbourne, you'll, you'll get amazing call back. Yeah, they're incredible in terms of their ability to just go through anything. And now I'm talking railway sleepers and railway steel and car bodies and things like that. You go through an engine block with that, and then back into sand or clay or rock or whatever. So pretty amazing some of the stuff you see come out of these things. When you, when you shake the sample out at the end, they usually come out and put them into plastic bags, samples, just like sausages, or you can put it into like a hard plastic liner. When you say they shake the sample out, so I've got a picture there of a couple of people holding a big long black. What is that drill rod? That's a drill rod, yeah. And is there a sample inside that or? So essentially that as that gets driven down into the ground, you would pull, that would be an outer casing that they've got there. You pull it up vertically and the head actually rotates to the side and you, you vibrate and you can use a bit of water to pressurize the sample and push it out, basically. And as it, as it comes out the sample barrel, you just come straight out into a bag for seals off and take it over to the, to the consultant, just the same as a direct push sample liner would be. Okay. Thank you. So I might move on to that. So that's essentially the same rig that's out at Coldstream landfill in Victoria. So that's installing a landfill gas bore. And basically I think that one was to 25, 30 meters, you can see in the foreground, the gravel. In terms of the whole size in that. HTTP that's going in 10 mil or 16 mil whole size per foot and then backfield with that gravel. So just give you an example. The guys complain a bit about the hard work. I'll tell you what, they get some pretty spectacular sunrises and whatnot. Not a bad job. Sometimes spoken like a true employer there, Pete. Let's move on to the next slide there. So bucket or go is something that we, we found out about for use in landfill mass from some drillers in the UK, we're having some issues trying to open up holes is as before. Sonic days. And, yeah, somebody just mentioned, if you use a big enough bucket or go. It's the size of the hole seems to be able to hold the holes open, at least for purposes of an installation. So we gave it a go and so that that's a photo of quarry park in footscray and we installed somewhere in the vicinity of 30 to 40 landfill gas extraction wells and manifold of them all together and essentially had those running to some methane loving grasses that were growing in containers and essentially a passive gas removal system that was fatis back in the day. But yeah, the bucket or go is amazing what it will do. They're expensive. That's probably to get one of those soil max out the site. It's quite expensive compared to a conventional or even a sonic jury. But the results are incredible. They really will go through anything. And so out at quarry park. When we were asked what we asked what we're likely to go through they said it'll be a building rubble so municipal waste. There'll be a layer of of telecom handsets from the 1990s. And that's and then you'll probably get into some some military vehicles such as you know like literally like military tanks and things like that so we didn't bring up any any that sort of paraphernalia but as a pretty amazing result with those things. So it's something to seriously keep in mind using a bucket or go if you're looking to open up a big, big diamond hole in a landfill. Just looking at that photo the the section the pipe above the ground is that the outside of the bucket or is that a pre collar. So that is the actual bucket and unfortunately there was an image showing that in a different sort of angle but that section that's coming looks like it's coming out of the ground that is the bucket. The rest is like I guess is part of the rig so you're limited to the depth you can go to you can add extensions to that but essentially like you are limited to probably depending on the size of the rig 15 to 30 meters of drilling. And it just acts like a Kelly rod so it just stays in place and get you know the bucket gets drilled down the depth of the bucket and then it gets emptied and then it takes another bite of it, it's sort of its length. And you just you continue on with that but it's really it's a quick process and it removes a lot of material really quickly. What's a Kelly, what's your call Kelly rod. Kelly rod is like, you know, there's old, old drilling styles where you have like a static rod essentially that's, that's always going up and down and then you just add to that. And so it's the same here so you, you have like a length of rod that goes through that Kelly drive which, you know, there's a, I don't know if you can see the rotating the section that would rotate that rod. The round bit kind of grabs onto it. And it just it just rotates that and then you can add to the bottom of it but it stays at its same length out of the ground and so it just it only has a certain stroke. So in this instance, I think it's about 12 meters. Okay. It's worth you tubing, because it's pretty hard to explain, but it's essentially it's a piling. So if you've seen a piling read your action, it's the same thing. They just they just drive sections down and then and remove them as they as they need to freeze. And this one is the cable to rig. And like I said, it's a 5,000 year old technology and that that read probably isn't far off that age. It's and that's what they all look like. Like, you know, you don't very rarely see like a brand new cable to a rig. There are always these rickety looking things with a couple of handles there coming off the mast and a whole bunch of cables and wire lines. And the idea is that you use the weight of the tooling. So like a solid slug. And it just drops to the bottom of the hole. And then you do that a couple of times and then you pull out a you change it over for a hollow tool with a flap that actually collects the material that you've just sort of busted up. And these things will just go through absolutely anything. They're incredible. They're slow, but they're incredible. So problem is, is that you don't meet many cable tool drillers who still have all their fingers. It's, you know, renowned for being a very dangerous type of drilling and not something you can really put a cage around so much. So those two handles coming off the mast, that's just like that's forward and reverse. And that's all they do. They just, they lift it and they drop it and they lift it and they drop it over and over and over. So it's really popular in the UK, people who have had experience over there drilling in the chalk. Well, no, this type of methodology. And it is, it's used here. A lot of groundwater drillers will use it down in the sort of fiery skips land around some of the rivers down there where you football sized cobbles. This thing will just go through anything. Yeah, but probably not, not something that I'd highly recommend on the landfill side. All right, so moving to installation of bores. So the purpose to install these boards is to obviously try and get representative samples of either substrate or groundwater lead shade or gas. And there's really two types of installations monitoring wells and extraction. Also, there's a third is injection as well. But for all intents and purposes monitoring and extraction wells and the construction materials that need to be considered based around what you're trying to do with the ball. So let's go to the next slide. That's just in brief that we're looking at groundwater wells, lead shade sumps, gas wells across the top there and the material type. So groundwater is a number of different material types like PVC stainless steel as dry points. There's reinforced fiberglass and there's HDPE sometimes leachate sumps predominantly PVC and HDPE same as landfill gas wells. So vapor is typically PVC stainless steel. This aluminium is used in those beacon samples. And then the multi levels are more the sophisticated system. I want to get you to talk to those in a bit, Richard. So I might just move in and talk about the different types of material PVC. So it's UPVC on plasticized polyglon chloride. The benefits are that it comes in a range of sizes. It's pretty easy to extrude. It's cheap. It's light. So it's really easy to handle. It's non corrosive, which is great in a lot of conditions. I guess the disadvantages are that it's relatively low in compressive strength. Because of the dynamic nature of landfills and a lot of subsidence and whatnot. Over time, quite often you'll find that you'll install a bore within months or a year or two. It'll have sheared off. And if you've got monitoring equipment down there or if you're trying to collect samples, then it just becomes a pretty costly process to replace over time. So just PVC on the outside of the landfill is the most commonly used material. So the top image there is two different slotting patterns. So the top one is groundwater screen. And that's usually 0.4 to 0.8 millimeter slots to allow groundwater to infiltrate into the well. The one below that is a landfill gas bore. And that's typically a 2 millimeter. They suggest 2 to 4 millimeters, but usually about 2 millimeters. And the spacing there provides 10 to 15 percent open area for gas to infiltrate, which is an EPA requirement. Below those is just an example PVC again, but a prepap screen. So in instances where you do have some collapse, you might have like a sandy clay or clay sand also in a silty sand. You've drilled down with an auger and you want to install a bore. You can push something down through it, but you're not going to get any filter pack around to really filter out the groundwater and to get rid of the fines as they come in. You can essentially have a pre-packed filter pack, which is just sand around that screen with a stainless steel wire mesh. I can't remember the micron for that screen off the top of my head, but essentially it's ready to go. It can be pushed down to depth and you've got already made well without having to try and pour sand from service. Are they quite commonly used? Yeah, they are actually. We make them ourselves and I've just put in another order for 20 to go up to Sydney. They get used more often than they have in the past. I think people are starting to see the benefits of those. When you're deploying those, so do you then put an additional sand filter pack around the outside of that? Or that just goes into your bare hole? Yeah, so what we typically do because if you... So let's talk for example for like an Elm Apple well or dissolve phase, we typically screen across groundwater in that instance. And so you'll have a bit of that filter pack, that pre-pack, exposed above the water level. And that's probably, it's not maybe going to have collapsed around that so much. So we would typically measure off half a metre to a metre of sand above that section of screen just to make sure that we've covered off and we're not getting surface water infiltration. And also that the bentonite seal isn't going to clog up that screen. One more question. So the slot sizes in the top one for the groundwater, is that actually specified in any guidance documentation or that's just what's generally... I think it's typically industry practice. We will often get asked for different slot sizes. Point four is standard. Occasionally we'll get asked for point eight. Different clients will ask for different filter packs. So for example, there's one client, there's probably a bunch of you listening now that ask for a finer sand than others. So we stock that separately for that particular client. And they'll ask for a point four wheel screen where others will... And I guess it depends on the hydro who's looking at the project and it also depends on whether you're trying to extract. If you're looking for a particular volume of water or flow rate to come out, you might decide that you want a larger screen and a larger filter pack. Do you recommend the sand size as well for the filter pack? Yep. So eight on 16 is the sieve size. And that's around two mil. On average, a two millimeter grain size. It's specified that it needs to be a rounded to well rounded non calcarus material. So it's typically just silica sand. And yeah, that's the usual size. The size that we also get asked for is 16 on 32, I believe, which is a finer sand. So that's, I think it's around one mil. When would you use that? Is that for your gas wells? No, only when that particular client asks for it. For the gas wells, for the two millimeter slots, we use between five and 10 millimeter aggregate. You say you can use, it's best to use sub rounded pebbles, river pebbles. Occasionally you can use that quarter minus, you know, blue stone chips, but the preference is for rounded to sub rounded, so silica based material. And washed is very important that it's washed. So you get rid of all the fines. Thanks for that. So stainless steel is another option for using in and around landfills. Obviously, ladders can be pretty corrosive. So mild steel doesn't last very long in there in a lot of them. So the stainless obviously has that benefit. It's very strong. And probably one thing I'll say about PVC just quickly is that it's rapidly decreases in strength under temperature. So at around 23 degrees, you get your maximum strength. And as you get up to 40 low 40s, you probably about 50% strength. And it doesn't take much once you have 60 degrees, which isn't uncommon in the lead shape. You're around 20% strength. So stainless steel obviously has the benefit of not having the temperature constraints. You can connect it to PVC, just have the screen and the sump below it. And stainless steel, which can be a cheaper method because it is quite expensive. It can be threaded and it can be welded on site. It's not a great idea to have a blow torch out when you've got concentrations of methane pouring out of the hole. But you do have options with that. It's available in lots of different diameters as well. So it is a pretty good solution, but it is expensive and it can be subject to biofouling. But that's more of a grab on a resource issue rather than landfill, I think. It's not the material of choice, but it does get used quite often. Just a note of caution for people. Sometimes the internal diameter of the casing at the surface, like it might be fiberglass or PVC, that's been an end of depth. You've got, say, a stainless steel screen. There are actually slightly different diameters sometimes. So you can lower down pumps and fit in the internal diameter at the top, but then get wedged in the stainless steel screen further down. So before you do your sampling, I'm going to take a look at the side of things that's a good idea to check the well construction records, particularly on some of these deep wells. It's just a note of caution. Yeah, so the last one that I'll see is kind of, this is the material of choice in the landfill mass. So high density polyethylene, HDPE. It's used in the majority of leachate wells and gas extraction wells that we install. It's obviously a very flexible material. It's really strong. The fact that it's flexible means that you do get a longer life if you do get movement in the landfill. It doesn't shear. It doesn't become brittle essentially, so you can still use it to a large extent. You can butt weld it or electrofusion weld it on site and given that you just use a hand drill. I mean, we perforate these with machines in our warehouse, but you can easily drill them on site. So a 10 mil or 16 mil drill bit and a hand drill with a bunch of batteries and you can just go for gold. Now, they're typically drilled at 90 degree intervals, 100 mil spacing, but it's totally up to the consultant to the client who whoever's installing them will determine how they want that perforating pattern done. Obviously non corrosive and plastic and not really adversity affected by temperature. So these have become the material of choice for landfill installations and you'll see them everywhere. If you're driving past a Clayton landfill, the plethora of landfills out east, you just see these things popping out of the ground everywhere with headworks and well, the manifolds of the same material. So it's very easy to work with. And yeah, that's probably the material choice for all of these types of wells and sumps. All different types of wall thicknesses, diameters. And you can attach these to steel screens as well. So very versatile. In terms of cross contamination from the material, is there any risk or any issue with that versus PVC? Is it an issue? Well, I think both are quite inert. And that's my understanding. And I think the degradation of PVC over time, whether it's by UV light or whether it's in a corrosive or acidic environment, the PVC tends to become really brittle. The HEPA seems to stand up a lot better than that. Whether or not you get leaching of material, I'm not too sure whether that's of concern in the leachate material itself. I assume it's been testing. I'm just a low lead drill off Richard. So I don't have the facts around the analysis of that. But I would imagine that it's inert enough to get the level of accuracy that we're looking for in these types of assessments. And the colouring of the lines, does that relate to the internal diameter or external diameter? It's actually to do with wall thickness. The blue line, I find it quite confusing because sometimes we'll ask for a particular pressure rating on HDPE and it will come with the blue line. Others will come and they'll just be purely black. So, yeah, that's a good question. I like the blue line. For some reason, I think it looks better. But I don't know that there's a massive difference in terms of quality or whatnot. But it tends to come to us in that colour. Having said that, we've got 12 meter lengths being perforated right now, which are purely black. And they're quite thick wall as well. But these things come in. I mean, you would have seen some of the culverts that they do in this PE. It's like super strong and they can be meters in diameter. Again, extruded to whatever diameter you need, really. And it's a really good cross promotion. This is a company called Matrix Piping. They're actually, I think they're based up in Swan Hill that we tend to work a lot with. They make fittings and pipes and whatnot. And we quite often receive their emails as well. So, pretty close connection with those guys. But that picture down the bottom on the left, you can see it. That's an electro fused end cap as well, I believe. So yeah, and then you essentially just hook those up to a power pack and press go. And it runs an electrical current through, melts the plastic and creates like a really hardy seal on it. So yeah, they're very easy to work with. That term you mentioned before, butt welding, was it? Yeah, yep. So that is essentially a machine that you put two pipes from either end. It's got a cutting tool on it. So it cuts a really smooth edge on each. And then it's got an iron, like a heating iron. And you place that in the middle and then you press go. And it essentially drives both pipes into the centre, into contact with that heating iron. And depending on the material, there's like different lengths of time that they need to be heated, depending on wall thickness and quality. And you then remove the iron and then the machine pushes the two heated ends together and forms a bead. Obviously under a certain pressure over a certain time and they become as strong as the pipe itself. I've never seen one break on site. And as you see the guys putting them in there, like as you put these in, sometimes there's like a lot of flex. And so those joints are under a fair bit of pressure. I've never seen one go. So they're really portable way of doing it. And they're reasonably cheap, very accessible. There's lots of places who hire them out. And we do that ourselves on site, typically. And yeah, so just a quick one on dry points and vapor pins. So these are for in situ grab samples essentially of water, typically groundwater and gas. And there's a few different types. So on the left there, you've got the solid screen, which you drive down into sandy materials. And as soon as you're into the level of water that you want or gas that you want, you can retrieve that through the Teflon tubing. The one below that, the second one is a sheath screen. So you can drive that down through a clay material and you're not going to get smearing over those ports. So you're driving down to depth, maybe just slightly past the depth you're after and then retract and the screen comes out. So it's kept clean from clay or any sort of sludge. And get your sample again that way. The picture on the right hand side, a bit blurry there, but that's a sort of paper implant. So we utilize those a lot on petroleum sites, less used on usually PVC for landfill gas sites. But I think these do get used occasionally. But yeah, essentially we would, you know, you drop that in, there's a weight down the bottom there. You drop that into an open borehole, cover the implant, which is 150mm length. Cover that with sand and then run Teflon tubing to the surface. And then the consultant can come past with a landfill gas monitor or PID or LEL and get a reading from that. So that's not sure that's drilling and insulation materials. So I'll probably hand over to you, Richard, for the more technical stuff. Thanks very much, Pete. That was excellent. We thought it would be worth just talking a little bit about some of the specifics of the drive points and multi levels, which is something that HydroTerror does quite a lot on. These figures are all courtesy of Solvanced, who we work with. So you don't always need a drill rig. OK, so this is a schematic on the right here. This is just a slide hammer that you typically use for belting a star, pick it into the ground, and that can drive your drive point in. One thing to note is you can actually get a wide enough drive point to stick a pressure transducer into it if you want to get real-time data-logged readings from these things. There's obviously depth limitations. I don't know. Many people have belted these in more than about four metres, and you put galvanised, the bottom section is made of stainless steel, but typically we use just galvanised steel extensions up above to belt them in and they can be sourced from places like Bunnings and that sort of thing. So the critical piece is the slide hammer at the top, and this top section is called a drive head assembly, and you're really sliding the hammer up and down against that, and it's pushing these into the ground. Some people ask, can they be reused? They can, sort of, but it depends how far it goes in, because it can be quite hard to get it out. You can use a jack to pull it out sometimes. So that's what they look like, and that's one with a pressure transducer deployed in it, so it's got a wider diameter nearer the surface to do that. You wouldn't want to go too deep because, you know, it's a fair effort to belt these things into the ground, and if it's consolidated clay, it can be hard work, but for less consolidated materials and in areas where it's not easy to get a drill rig into, you know, like based on a slope, et cetera, this is a really good way to collect samples. What does it look like to collect samples from drive points? You've got this tubing bypass. They call it that because the slide hammer needs to be kept away from your tubing, otherwise it would split the tubing when it goes up and down, so they've got this bypass assembly, and you hook that tube up to a peristaltic pump and you can extract a sample from that. The sort of maximum lift you can get out of a peristaltic pump, in my experience, they're saying 10 metres there. I'd be saying sort of four to five metres, really, to collect a sample, but they are a good low-cost way to collect samples, and you can collect samples in remote locations. Some sort of projects, we've used them on include actually belting nays into the base of creek beds and things where you're looking at upward flow of groundwater as well. They can also be used for collecting landfill gas, so you can belt them in and use them for that application as well. Okay, so under true multi-levels, there's a couple that HydroTerror is familiar with. CMT, which is continuous multi-channel tubing, and the other one called the Waterloo multi-level systems. Both of these are made by Solance, and the idea is that you can monitor at discrete depths. In some applications, you'll be monitoring both for gas and for groundwater levels in the same setup, which is one of the real strengths of, in particular, the CMT system. So we've used them in both landfill gas and groundwater applications around landfills. This is the sort of well-head of a Waterloo system. What does it mean, multi-level? It means you have multiple levels that you are getting water in from, so multiple screened intervals, which means you have multiple outlets at the top to collect samples from, and also you can dedicate things like vibrating wire piezometers and that sort of thing in those ports to collect the pressure head at those discrete intervals. They're not easy to install. It takes a bit of time to install them. The sonic rig that Pete was showing us is a good way to do these, because it keeps the hole open. What's a Waterloo system have as its components? Well, that's the well-head. You can have permanent packers to isolate zones. So they're effectively like having a bentonite seal, but they're pre-built, a bit like Mike's pre-built sand pack. In terms of dedicated ports, they're made of stainless steel, and you screw them into the casing so you progressively build this as you lower it into a well. And you'll see at the top of that stainless steel section, you can attach there. There's a pressure transducer attached to that, which would be measuring the groundwater pressure associated with that port. So you can have up to 24 of those pressure transducers mounted in one single Waterloo system. So that's pretty impressive. I don't know of many applications where you're going to have that many variable heads down through one hole. The sorts of applications for these devices that are related to this topic have been used around nuclear waste repositories and that sort of thing to monitor discrete fracture sets and that sort of thing in the US. In Australia, we've used the mooring mining applications where we're looking at studies like groundwater surface water interaction, that sort of thing. That's what they sort of look like, I guess in cross-section, you've got packers and you've got ports. So you're isolating zones for water to flow in through those ports and you're using the packers to isolate those zones. Various different configurations basically showing the same thing there. The second one is this CMT which stands for Continuous Multi-Channel Tubing. You see these little pictures in the middle here. You'll see that you can have three channels or seven channels. Each one of these channels can be set up as a discrete zone to sample from. So you literally physically cut a hole through the side of one of those channels at the desired interval you want and so you're effectively custom-building a port which you then wrap stainless steel mesh around it which is on this right-hand picture they're sort of showing what that is. So the multi-channel tubing is made of polyethylene and then you've got this screen which is made of stainless steel mesh that goes around that and you've got these old TECA clamps which are a bit like a hose clamp that goes around them to hold those screens in place. So the real strength of this is let's say you're trying to intercept landfill gas at a particular layer you can build that screen length to your desired screen for your target interval that you want to put in. At a deeper level you might be sampling for groundwater you can cut another discrete slot to sample from that at a different depth. A bit like the Waterloo system you can isolate the zones you can get bentonite packers that attach to the outside of these so they're pre-packed or you can manually do it with your traditional bentonite pellets and sand around the actual screened sections. Just some examples of how you connect up to the various things that Pete was talking about. If you are wanting to connect up to the gas wells that sort of thing just keep in mind that your job's not done once you've put a well in you also need to configure them to actually be monitoring so consideration of how you're terminating these at the surface and what ports you've got what connect fittings and that sort of thing. So these are examples of continuous landfill gas setups installed on gas wells and you need to keep in mind that there can be vandalism and that sort of thing so we often build enclosures around this sort of thing as well. When you're sucking gas samples particularly for continuous applications you've also got to make sure you've got a filter in place to get rid of the moisture otherwise it can affect the sensors and that's what that capsule is on the right hand side of that enclosure there. Finally on the sumps you know so Mark's been talking a bit about leachate sumps few considerations practical considerations when you're trying to deploy monitoring equipment one is often they're sealed right they're trying to collect gas as well as leachate in these particular sumps in this instance we've deployed a bubbly unit which is a tube that attaches to the pump line that comes up from the pump and you literally just take them to them and you bring the tube up and it comes into this bubbly unit that you see there so that's one way to do that. Other ways to monitor within those sumps is to use pressure transducers but keep in mind you need to be able to bring those fittings up back through the caps and sometimes you've got to think about intrinsic safe issues as well. Now we're running out of time so we better get on to the questions we've got quite a lot that have come in but just in summary what have we learned today importance of correct well and bore installation is a must have for accurate data collection if we get that bit wrong it doesn't matter how good our monitoring equipment is we're not going to get good data that we can apply. It's very important to choose the correct drilling method I think we've seen some really good advice around that in terms of well construction materials I think this webinar has provided good guidance that there's a couple there that we can use just PVC and stainless steel etc but keep in mind cost considerations my recommendation is you talk to your driller there are many different types of wells so we saw drive points, mouldy levels standard well casing choose carefully I'd also say look at your geological information prior to going to site if you've got it or if you're on site on the fly try and work out carefully what length of screen you need it's often where things can go wrong think about how to connect to wells and sumps having the correct fittings at the surface and enclosures is important and keep in mind that landfill gas can become explosive methane is an explosive gas so you need to think about those considerations as well all right so Pete without further ado I'm going to head to the questions and hopefully you're going to provide the answers I'll try to answer these really quick no worries so question number one legislative approach in the application of these various drilling methods so there's obviously there's environmental legislation that needs to be considered there's health and safety that needs to be considered but from a regulatory consideration we have these landfill gas construction requirements that's probably the one I'll focus on so EPA do require for a landfill gas ball you need 100 to 150mm diameter ball drilled with a 50mm OD casing doesn't specify the material it's typically PVC a 1m bentonite seal 10 to 15% open space with 2 to 4mm slots 10mm diameter gravel that's a pretty specific regulation terms of environmental regulations we obviously need to make sure when we're drilling with these various methods that we're not harming the environment things like contaminating groundwater resources drilling through a landfill going through a seal at the base and into the aquifer which would just be a really demonstrous result so we're very mindful of that and obviously having good information about landfills before you start drilling is great but it's not always the case it's always a bit of a challenge and so we would generally be really cautious of how drilling too deep in them there's different classes of drillers as well so that's a way to I guess look up make sure that we maintain environmental don't contaminate other aquifers there's class 1 and 2 so class 1, 2 and 3 class 1 can work in unconfined aquifers class 2 in multiple aquifers and class 3 in artesian aquifers so there are some regulations around those things in terms of drilling and construction and bores and then the health and safety is massive on every site we work on especially when we're out on particularly these tier 1 infrastructure projects it's pretty amazing the hoops but some of the real basic ones are cages, e-stops on rigs and just PPE on a landfill site and obviously there's particular PPE that you would use which I think I'll cover in one of the other questions Alright question number 2 decommissioning of groundwater wells best practice versus common practice Alright so in outside of a landfill the the most common decommissioning process and the one that is I guess accepted by the minimum construction requirements or the preferred method is to grout the entire bore so from the bottom to the top and that can be just a fully cementous grout or it can be a percentage, say 2 to 5% bentonite mix to give it a bit of I guess rubberise it a little bit a bit more of a seal but in a nutshell it's grouting the entire thing we occasionally have clients say well we want to put sand across the screen section and that's fine as well it's not a requirement but trying to decommission in a landfill I wish I could show you a picture of it it's actually a picture of my dad about 10 years ago out at a landfill and we tried to do it using cement bags and once we got through the first pallet of cement bags we audited a 20 ton agitator and we released the entire agitator into into one borehole and didn't fill it so we essentially filled the landfill and not the bore so just be mindful if you're trying to decommission any bore if you're having a significant loss you can use bentonite and say in that instance bentonite chips is ideal they have to pay a levy on that next question in landfill sites have known or suspected asbestos contamination how do you monitor limit fibre exposure and silica dust yep so for for the contractor we typically govern by the site operator or our client as to the levels of expected fibres and dust contamination particularly asbestos air monitoring for asbestos is really common so that would just be in our work space and typically in spaced locations around the site they'll have air monitoring which gets checked daily but for our guys it's there's no we'll just essentially be wearing Tyvex suits P2 masks, nitrile bulbs undone bulbs all the usual things I don't like in that space just remove any kind of dermal contact and any potential for inhalation you just can't take any risks especially in light of recent events with silica dust and things like that so keeping the area moist as well is really important so just wetting down your work area just to keep that dust down okay next question well designed for LNAPL and DNAPL detection and monitoring yep so LNAPL the short answer is screen across the groundwater interval and we would typically if we were putting a three meter screen we'd put two thirds of it below groundwater and a meter above where that becomes challenging is if you're using you know like compressed air so if you're in the Silurian for example and you blast a whole bunch of air down to 20 meters and then you go to install well quite often you've driven groundwater out into the formation you come back the next day and the water level sitting above your screen and then you hope like crazy that when you develop it it comes back down which doesn't always happen so that's always a can be a bit of a gamble best if you can leave the hole open before you install it other issues like around SA augering through clays and where you can smear the water bearing zone and it can sometimes take a bit of time for that to recover and it can be quite hard to know but yeah again if you can leave it for a bit of time allow the water to recover back into the bore and work out where to set that screen that's ideal so yeah that's fairly straightforward. Dean Apple was a different thing together so it's so challenging to know what pathways it's taken particularly in Fractured Rock many people would be aware of the Barkley Street site and historically how challenging that's been to identify and then any chance of significant recovery of that sort of material but again there are ways of doing it flute liner is one way of mapping fractures and looking at fractures that are potentially transporting Dean Apple but yeah the idea at the end of it all is to put a sump at the bottom of your well so you don't have a fully screened well where the Dean Apple could just exit the bottom of the well it could be half a meter, it could be two meters but at least it will capture any Dean Apple that enters the well because it will sink to the bottom and you'll be able to sample it that's the short answer and along. I might just add to that so when you're actually doing your drilling and your logging it's really important to note the moisture as you go because if you wait for your standing at the water level to recover afterwards it can often be a very different elevation to where the waters actually float into your well so it can be a little bit misleading in terms of where you're screening so what do I mean by that is if you've got a bit of a positive head i.e. when you punch through a confining layer the water moves up the actual portion that you're wanting to screen is further down where you've actually hit the saturated layer so it's quite a common error that we see where people haven't noted that change in moisture when they've been drilling and then they've screened across too wide an area so just keep that in mind all right number five what are the management alternatives and matrix drilling services to facilitate the disposal of spoil from drilling works hmm yep it's a massive component of the cost of a drilling program and it's one that sometimes I wish I owned a landfill Richard sometimes or a treatment facility because it's just incredibly expensive but so generally we'll put any spatable materials into 205 litre drums and we send them off on our drum truck which is an EPA licensed truck you have to have EPA licensed operators to drive those things in Victoria a bit different in different states and there's actually there's tracking of that waste where that's come from who's transporting it and where it's going to and then for water drilling and drilling fluids it's 1000 litre IBCs are typically the vessel but you can also use an NDD truck to come and suck out materials but we dispose to a variety of different landfills and treatment facilities Viola is one that we transport to in Melbourne Cleanaway in Sydney also but there's rules and regulations in New South Wales that determine like distances from sites you have to be within a certain distance you can't carry the waste over a certain number of kilometres you need to go to a more local landfill there's a lot of grey area around it I think we've got it pretty nailed down in terms of how we do it and in pretty close contact with EPA getting guys licensed all the time to carry that stuff so yeah one thing we don't do is store it at our Victorian facility it's not allowed so it needs to be moved on pretty quick from site to receiving facility but again it's so expensive and it's becoming more and more expensive to dispose of waste so if you can minimise it and that's great if you can keep it on site it's even better So most wells you drill on site I presume you dispose of the spoil at the landfill site is that right? Yeah and so it's a rough calculation for a typical borehole of 100 to 150mm diameter you would allow one drum for every 10m drill and so if you go to hollow workers you essentially double that and with a big investigation like you can end up with tens of drums which is yeah it's not a good look they don't like being left on site so they want to move them on pretty quickly because it looks like a toxic waste dump and you quite often get public voicing their concerns but I feel like there could be a better way Sounds like it Alright question number 6 Managing gas risk in dual purpose lead shape extraction and gas systems Alright I think we agreed on this one, I can only really talk to this in the context of managing the risk associated with the deployment of monitoring systems The main risk I guess we're dealing with and some site operators actually require us to have intrinsically safe equipment is the explosion risk and typically if we're concerned we use the bubbler tubes and have those bubblers that were in one of my slides that means you've got no electronics actually in the sump it's just a hard plastic tube that's running into and you put a burst of compressed gas down there each time you take a measurement so that's one way to manage those sorts of scenarios Now we have another 18 questions and we're 15 minutes over, are you happy to keep going for another 15 minutes? Yeah 100% Excellent alright So I'll just switch to the Q&A Thanks for all these questions everyone Alright Martin O'Rourke In my experience drilling a hole is a partnership between the driller and the geologist engineering geologist hydrogeologist on site Drillers may appear to be people as roughnecks clearly but most are skilled operators of their rig without good samples the geologist can't do their job so it's in the driller's interest to do a good job it's also in the interest in the geologist to not interfere too much It's more a statement than a question but do you have something to add to that Pete? Just that I agree and that I think the less teeth in a driller's mouth the better experience they've got and the more wary you probably should be of them most of our drillers have all their teeth That's a requirement I'm working at Matrix Thanks for that Next question Stuart Turlow In waste in waste tend to get a bore that has significantly reduced gas leachate yield I think we're talking about the yield when we've got a well screened in the waste Have you got much experience around that? Typically I haven't come across it I guess as a contractor where usually we put the well in and then we're gone so we don't I think I just saw something come up on that one you could say admin would like to answer this No, I don't think so I think it might be in the fact that it's exhausting it's a gas or a leachate I'm not too sure I think as the waste the grades and consolidates its permeability gets lower so I can sort of understand why that might occur We might move on to the next question How does cost of sonic the other drilling methods? Yep, so I'll give you a specific example conventional drilling with say a Geopro if they're an environmental site you would be looking at around $300 an hour sonic you'd be looking at $600 to $650 so double double the price that's a pretty standard price run Is it worth it? Yeah It actually is for what it does it's not a silver bullet in every instance but for the speed and ease of installation I think you would get double the penetration rate and double the amount of work completed using sonic versus some other conventional techniques Another question from Stuart Turlow What diameter hole can you drill with sonic? Can you achieve 500mm like the barrel augers? So up to 12 inch so you're looking at $300mm it's probably where it peed us out for most sonic drills there's probably bigger ones around the ones that we have around Australia and you wouldn't get significant depth you might get to 30m with that whereas the barrel auger starts at around $600mm and it needs to be bigger than that Kelly rod that we saw but they can go up to I think a couple of meters so yeah $300mm Stuart So if you want to install a sump in a landfill where it needs a sump on a closed landfill say would you use one of those bucket augers to retrospectively put that in? Yeah absolutely Okay Martin O'Rourke I saw a sonic rig used in the unconsolidated alluvium in the upper Namoi aquifer the return samples were amazing so quick too there you go I think you could probably sit on that one Pete that sounds like a good recommendation Stuart I agree bucket augers are by far best for waste having seen thousands of landfill wells go in I've seen concrete blocks engine blocks drilled through like butter like all rigs though they don't like mattresses kebab on the bucket do you want to add to that? No I agree augers are terrible once they get a bit of wire around them it's either worse if it's fiber optic Yeah well that's a bad day Is the bucket auger in land feel much slower than the comparison to say sonic or auger? Definitely faster than auger that it doesn't case out always gives me a little bit of trepidation but I've never seen a bucket auger hole collapse so in my experience they've been very good I guess you take small bites with a bucket auger you pull it out empty it and do the same thing with a sonic it's kind of the same you might take a 3 or 6 meter bite at a time and you've got to empty it out so they're fairly similar time frame the bucket auger machines they're absolute monsters big piling rigs they've got so much torque I would say the methodologies are very comparable in terms of time I'd say a bucket auger would probably cost more I'd imagine 10 grand a day is a typical cost for one of those rigs Sorry how do you just say the cost was about 10 8 to 10 Last time we used one Okay next question from Matthew Jessup Hunt Do you find pre-packed screens handle landfill conditions better than standard PVC? Probably not and I can't speak from experience because I don't think we've installed many PVC wells into landfill mass in terms of the exterior it's still a PVC well it's just got a pre-packed screen so it doesn't change the properties of the PVC Okay Emmat Del Borrello I've seen different classes of PVC used in monitoring well installation e.g. class 15 and commonly class 18 Does it matter which class of PVC is used? Yeah absolutely so the typical monitoring well for a 50mm well is class 18 100mm well is usually either class 12 or class 18 and as you get down to class 9 it's a strength thing and it's a pressure rating so you start to it's a lower quality I guess it's a cheaper installation but it probably doesn't have the longevity of say class 18 class 18 can be overkill in some instances if it's not it doesn't need to be high pressure so I typically recommend class 18 for 50mm and at least class 12 for 100mm and 125mm Okay now we've got a little concern here we've got someone questioning what we said Stuart Turlow I thought this is the colouring of the pipe stripes I thought it was relating to what the pipe was used for blue for potable water yellow for gas and purple for telecons I think that's 100% right I think and that's why there's not a huge distinction for what we're using it for but I think the blue being potable water it just distinguishes it from on a construction site you know what to tap into if you're trying to run water to a property versus running opening up the yellow pipe and getting a bit of gas coming out so I think that's my understanding is that that's the distinction Okay Thanks for that clarification there Jesse Simcus has got an interesting one it's relating to the butt welding does the butt welding cause an internal bead which can lead to equipment catching on it Yeah I think that's a really good question because the bead on the outside will be the same size as the bead on the inside and you usually get somewhere between 8mm of a bead so if you're trying to put down a really tight pump it might make you think instead of going 110 nominal diameter I might go 160 nominal diameter so I'm not going to get caught up on that the shoulder of the pump is not going to get caught up on that bead it is rounded so things will typically move past it but something to keep in mind for sure Jesse Okay Sam Levi Thanks Pete Are you guys also using the Geoprobe TM push run tubing Brackets PRT Method for Soil Gas Sampling Thanks Sam Look we haven't actually had a request for it but if we did we'd certainly look at getting that tooling it's really cool what that does so I won't go into it now but we have four Geoprobes and we're always investing in new tooling water sampling and drilling tooling so if you're interested in using it I'll buy it There's a commitment Alright Question from Graham Ross I'm aware of a number of suburban historic landfill sites that are not listed on the EPA landfill register I assume that there are no requirements for councils to monitor these what are the requirements for monitoring closed sites Yeah I would have put your order to hat on there at all A little bit rusty on that stuff That surprises me that they're not on the register Yeah the councils do have they do have most of their abandoned or closed landfills mapped and most of them have an overlay on them with designated buffers around them but if they're not covered by that I would have thought they'd be covered by the contaminated land overlay but good question Graham it might be that they are on a some kind of planning control under a planning control but not sure they probably should be anonymous attendee what is the correct drilling method from slope how can we get soil samples from slope I think they mean drilling on slope Yeah it's a really challenging situation when you're on a slope and the machines typically all our machines are track mounted and they have a cutoff so at a particular angle they just won't turn off because they're like well you're going to flip me if you keep going like this the easiest way of doing it is to create a flat area to drill from and all of the machines including the sonic can be claimed in so it might be really important to get a hole done on a slope then you can create a flat work area using excavators they tend to be able to get anywhere because they've got the weighted boom and you could get a machine either craned in or create a cut-off pathway to get there so there's ways to do it it's expensive so it just really depends on how important it is to get that location drilled okay another anonymous question is there a particular reason running temporary casing is not frequently used even when drilling through multiple aquifers this is standard practice in the US and UK yeah look it's something that comes up all the time for us because when we're doing work day in day out you know that you could run a casing say for example you'd run an SW casing down to a clay layout at 10 meters and then you could run a PQ or HWT through that and we know from experience that it doesn't leak for the period that you're doing the works you could install a well put a gravel pack seal it and then grout it and in the time that you've drilled that well the cross-contamination is really really low it really comes down to client risk appetite and there's generally none the idea of there potentially being some cross-contamination between aquifers kind of just nullifies the question they just say no it has to be grouted in it has to be done, it has to be left for overnight or three days and then come back and keep drilling which for us it just means things take longer we get to charge more so I shouldn't complain but we think that there's definitely efficiencies and given that they do it in you know I'd say more advanced but places where they've been doing it for longer successfully I think hopefully people will start to be a little bit less risk averse to it I do also understand that there's massive risks involved all right I think we'll just answer two more questions we've gone over our second deadline Justin Dory he's got a pretty long question slash comment here Pete a few things have you ever looked at ODEX for methodology yes it's a really really cool system so just in a nutshell hammer but the bit essentially has one or more wings that can be set off from the surface if you think about the drill bit will actually fit through the casing so it's a casing advanced method the drill bit will fit through once it gets through the bottom of the drill tooling or the casing you can flick a switch at surface and activate these wings which pop out and you can cut a bigger hole than the casing which allows the casing to just drop in behind it that's remarkable for overburden on mine sites and I think they use it in some tailings stands but typically for mine sites where they're trying to get through the overburden really quickly set a casing and get to the ore body so we have looked at it it's quite expensive we've never been asked for it so again one of those things now that we've got sonic we probably wouldn't deal with it but it is a really really it's a tried and tested methodology what does it stand for or is that a brand name? I don't know it could be a brand name I think Odex all right then next part of this question in general for everyone if your job requires hollows or additional off-site as expect additional costs yes so basically hollow orgas are expensive we've used sonic a couple of times for geotech and it can provide limited data but not as useful as other methodologies and if geotech is required Enviro should consider additional bore holes on that point we quite often do combination Enviro and geotech holes once you get into the rock Enviro's aren't overly interested because most of what we're looking for in Enviro is limited in the unconsolidated material unless you're chasing groundwater and contamination in the fractured rock so it's very common particularly with tier 1 companies where they have tier 1, 2 and 3s in a geotechnical group they'll do a bit of cross work using the same bore hole but I agree any additional bore holes is always good for me so do you think that it is limited in its application for geotech I do particularly look I'll qualify that so in the unconsolidated material it's no different to any other conventional methodology you can drill down you can run an SBT you can push a YouTube so you can get all of the information you would typically get in unconsolidated formations once you get into rock sometimes if you're in vesicular basalt sometimes you pull out a metre long stick of basalt you'll see fractures the potential for it to shatter the rock and then I guess you can an experienced geologist might be able to look at it and go okay well that's a fracture fluid's been running through that fracture or it's oxidised or something versus this one which is fresh and I can see which is which but just adds a level of complexity to logging something that's already a pretty challenging thing to do when you're in fractured rock so I think diamond coring is by far the superior method in rock okay you spoke about PVC and degrading with temperature the temperature of grout going off especially in deep groundwater monitoring wells can weaken the PVC and people should consider stainless have you had that experience look I think that's a really reasonable thing to to discuss and I don't know that there's been a lot of discussion about it but you know you get this exothermic reaction and obviously it's you know there's going to be potential consequences I don't know whether it gets you know we'd create a massive drama I've never been recalled back to re-drill a well that's been damaged by the grout but I think it's a really reasonable comment stainless is awesome it's just the expense of it I think is what precludes it from a lot of assessments Liam wanted to say hi I am and were you at Monash and did you study under Pat Vickers Rich were you at Monash early 2000s and yes I did there you go we're re-uniting people here today last question I think we might select Paul McGrath today Paul haven't seen you for a while okay for the people we haven't managed to answer we will send out some emails in an effort to answer your questions and we'll circulate them to everybody so Paul McGrath EPA EPA Act focus on the GED which can be achieved by duty to manage and duty to notify so councils with old closed known landfills have to follow those requirements which should mean need to scroll down a little bit which should mean once known goes on the landfill register based on risk the landfills may or may not have buffer distances applied not all councils have buffers on planning systems there is the ability under the Act now to insert buffer overlays but people in these buffers may oppose councils putting them in so that was really in response to our earlier question about where councils have landfills that aren't listed so just to read that again um councils with old closed known landfills have to follow the requirements set out in the EPA Act which should mean once known these sites go on the landfill register ok so based on risk the landfills may or may not have to have buffer distances but it sounds like it's a little bit of a can of worms if you owned a house and council suddenly put a buffer over it you probably wouldn't be happy so that's thanks very much Paul for clarifying that one apologies to everyone questions we didn't get time to read out if you if you want to get your question read out get them into the early birds a question many thanks for those early bird questions as well that came through and most of all many thanks to Pete from matrix drilling for putting on a fantastic presentation today thanks very much everyone thanks for having me and I you got something out of it and feel free to give me a call any questions I'm more than happy to field drilling questions all day every day I love it and congratulations you had more than 30 300 registrants today so that's a fact to give it clearly a good driller well done mate well done appreciate it thanks everyone cheers everyone