 Well, thank you all for joining us today for the latest in our Hydrotera webinar series. Got a fantastic turnout today, and I think that goes to show the reputation of our guest speaker today, Nick Simmons from Australian Environmental Auditors. So today's topic is on landfill monitoring, and we will be covering a range of issues that are associated with that. And then we're going to be looking at some technologies to help with that as well. A little bit about our speaker, our guest speaker today, Nick Simmons. So prior to his current role, Nick was EPA's principal environmental expert for landfills, and he, in Victoria, and he filled that role for several years. Since then, he's entered the world of the private sector and seems to be doing pretty well there too. And he is now principal technical specialist and auditor assistant with Australian Environmental Auditors. So welcome to you today, Nick, and thanks very much for participating. Before we charge into all things technical, this is very important. We like to get your feedback. It's really a two-way street these webinars. So there's a Q&A button at the top of the screen, and this provides you with the opportunity to log a question, which we will then read out at the end of the presentation and attempt to answer it. If we can't answer it during the session, we will get back in touch with you post-presentation with an answer. But remember that. So use the Q&A button, please. Why does Hydrotera undertake these webinars? Well, we're passionate about sharing knowledge, and we tend to be a bit of a conduit for knowledge. We have a lot of suppliers and specialists who work with us, and it's one way to share knowledge, both of our suppliers and organisations we work with. We're passionate about education, and we do collaborate a lot with universities and that sort of thing. So we see this as another form of education for the industry, and we really appreciate the positive feedback we've been getting around that. And finally, we try to take a leadership role in the industry. So we are typically aware of new technologies and that sort of thing before many of the people in the industry, and a critical role for us is to be sharing that knowledge with you. So today's webinar, as I mentioned, is all about landfills. So Nick's going to talk to you about the importance of landfill monitoring to protect the environment, environmental management plans for landfill regulatory compliance and auditing, and landfill performance and risk. Then I'll be talking to you about what we can measure, what are our monitoring options in terms of technology, and then I'll be showing you a couple of case studies. Finally, we will move over to Q&A, and we'll have about 10 or 15 minutes for Q&A, I would think. So without further ado, I'm going to pass the reins over to Nick. I'll be driving the slides from my end, so if we get a little bit out of sync, apologies for that, but we will do our best. So over to you, Nick, and thanks very much. Thanks, Richard. Thanks to everyone coming along today as well. I appreciate probably a lot of you have heard me prattle on about landfill several times and you've come back for more, so that's a good thing. So we'll just start off with why are we care, really? Why are we monitoring? What are the things that landfills can do to the environment? And there's a few juicy pictures that I've swung on the right-hand side there. So we've got a pretty obvious one. You fill a landfill up with waste, it generates leachate. Leachate's fairly highly polluting liquid that can impact groundwater. Should it get there? You can get service water pollution as well. So you can have leachate breaking up from the landfill itself, service water that's hit the waste, or interaction with groundwater that's been polluted by leachate, subsequently with service water. Biggest hazard by far to humans anyway is landfill gas migration. That's catastrophic when that goes really, really badly wrong. And that picture you can see at the very top right there was 1986 in the UK, where it did go very badly wrong. No one actually died, but there were three people in that building when it exploded. And then we've got the fact that landfill gas stinks as well. So those emissions at the surface get picked up, carried by the air, and over to a receptor. And one thing that came about and is increasingly recognised, and rightly so, is the psychological impacts that that can have when people are living with odours all the time. Not least because it annoys them, but a lot of people, because they don't know really what landfill gas is made of, they assume that it's bad for their health as well, because they can smell it. So they have this bad situation where they get in the head a few problems. And then overall, those emissions of landfill gas being methane and CO2 are obviously pretty potent global warming gases as well. So they're the general impact. So that's why we monitor, we're looking to evaluate how good or bad those things are. Thanks, Richard. So I'd like to start with a conceptual model that really shows what we monitor and where the CSMs are, an absolute cornerstone of the work that we do. And just to allow you to understand the classic source pathway receptor linkages. So the source is the landfill. And the pathway is the route by which something from the landfill that is bad gets to a receptor, which is something that can impact in a negative manner. So if we just go start right through to left, I'll focus this on the things that the EPA is focused on, which the environmental monitoring programs that auditors verify are focused on as well. And all of these have various performance standards, emissions limits, action levels, etc., associated with them to evaluate whether or not there's a problem. So the landfill gas, we've got it entering buildings on or adjacent to the site. That's not good from that asphyxiation and explosion point of view. Immediately to the right of that, all we've got subsurface services. So, you know, Telstra pits, water supplies, gas lines, all that stuff. If it enters those, they can become conduits for its movement. It's important to understand it's not the actual pipe itself, the pipe is sealed or whatever it is. It's the backfill around the pipe in the trench that it will move through. That's where we tend to find it. There are certain underground bodies that can enter like a Telstra pit, you know, but when it's a pipe, it doesn't go in the pipe, it's around it. The surface emissions directly out the cap or directly out the landfill surface, but there are only action levels in Victoria for whether there's intermediate cover or a cap in place. Then we've got the subsurface geology, the red arrow to the right there. So gas moving out of the landfill underground through the geology and that can interact with the subsurface services one where it can go geology, services, geology, can go services, geology and vice versa, depending on what's present. Considering leachates are on the brown arrows now. Leachate straight through the Vado zone into groundwater. You can see the groundwater is the blue line. If that water is closer, then the risk is higher. You can have online sites that are sub-water table where you've got waste in contact with groundwater, so more problems there. Over to the right, that leachate can then hit the groundwater and then that groundwater can move and interact with the surface water body and pollute that as well. Then you've got that overland leachate flow if it breaks out from the landfill or if you've got storm water that's hitting the waste and running off into the surface water body. The one that's often not considered, I put it in here on purpose for that reason and we discuss it a bit later, is that leachate radial flow, that one going backwards. So if you can see I've got groundwater flow going left to right, but radial flow going against the inferred groundwater flow and that's something that is not often considered, but I'll park that for now because we'll talk about that when we get to groundwater. But conceptually, keep that in your head when we're talking about the stuff that we get to because that's the crux of it right there. So some fundamental stuff before we get into it. I just clicked down one more time for my Star Trek next-gen joke. So absolutely number one thing that I saw in EPA and I continue to see as an auditors assistant now is poor monitoring data and it can be poor for a bunch of reasons that again we'll get into a bit later on but if you've got poor data you don't have a full story so it's a problem. A really key thing that I like to see and I don't see enough of it is that monitoring data is not just collected because the regulator tells you to collect it. That's actually for you to look at and use as feedback on how well you're doing. So just take landfill gases as an example right. So if you've got gas migration that starts appearing in the perimeter pores at the edge of your landfill, someone's going wrong, it's telling you you've got to manage it properly, it's going to do something with the gas field or something else. So use that as feedback and over time you get that provenance of data where you can look at change over time and go yeah we've managed that well and now we've got a problem, we've got a large data set to be able to use to evaluate your environment performance. I want to just put this out there because I got a lot of questions about this still since I left EPA. The first part is you know use the EPA guidance that's what it's there for. But right as of now continue to use Bethan because it's still in force and in use in the new app world because it hasn't been replaced yet. Intrinsically linked to that if you've got a EMP an environment for monitoring program it's going to be your order to verify if you have audits done on your site and that's going to contain what you need to monitor how and when and with what. So it's a guide you please use that that's what it's there for and and if you're conversing with the EPA or your auditor and you haven't done it as per EMP or your consultants haven't done it by EMP or you're the consultant you can't do it for how the EMP says you know that's not in the world. Note down why have a correct divest but then tell the EPA tell the auditor about that. I couldn't do this that way because this is what I did instead or just flat out couldn't do it. It's really difficult as a regulator but also as an auditors assistant to work out what's going on if we've just got no information because and we're not being told because we don't know you know the auditor audits what's given to the auditor so you know you have to give us everything and please use other state and territories and international guidance as well there's no issue whatsoever with that. There's a lot of the time guidance has not been reproduced because there's no point reinventing the wheel so there's no there's no issues with we're going ahead and doing that. An example is the British standard for you know BSA485 for ground gas and landfill gas risk assessment. I think there might be one more Richard or maybe it's the next slide. Yep and I think I've probably covered off on that sufficiently already but you know use your auditor as a resource engage with the auditor and the same goes to EPA. Hopefully that's the experience you had of me when I was there. I firmly believe my role was to help you know as well as as well as do the you know the the regulatory stuff. Okay so we'll go straight into landfill gas monitoring so it's just an overview at first and then the way I've structured this is here's what you do in a very basic one slide sense but then I've moved on to some of the pitfalls and things that can go wrong things to watch out for when you do those various types of monitoring. So for the subsurface geology we're looking in terms of gas action levels so EPA performance you know criteria for regulatory purposes you're looking for methane and CO2 or lack of hopefully and that's from monitoring boards you know sunk into the geology around the edge of the landfill but critically they've got to be at least 20 meters away from from the waste mass if they're too close and you're probably going to get landfill gas there because of the sort of general halo around the sites that you get even when it's well managed. So it's generally accepted that 20 meters is the point where if you've got a bore there and you've got gas migration occurring you've got a problem that needs fixing. Now when I say at least 20 meters away you know around there you know don't put the five kilometers away right because that's not going to tell you anything either and that's done with the the unit or what that's one type of unit you can see to the right hand side of the screen with an extractive landfill gas analyzer there are various types. To find out which ones are okay use EPA publication 1684 because when I wrote that I put all the performance standards in there so if you're looking in the monitor and you want no it's all right grab that publication and see if it's good. Surface emissions speaks for itself it's emissions of methane so not CO2 just methane at the surface all capterias all areas with intermediate cover but don't forget the features so if you've got leachate some sticking up you've got gas well sticking up you've got cracks you've got holes or the random bits and pieces sticking out a big patch of dead grass and multi-beautiful grass you know they're the features that you'd want to go and have a look at and see what's happening with with methane emissions at that point. That's normally done these days with a TDL 500 or a Hubeberg laser one to less extent an FID the TDL and the Hubeberg they're both methane specific the FID is not methane specific it will pick up anything that burns but the assumption correctly is that what you're going to pick up the burns at the surface of a landfill or around landfill is going to be majority methane as in like 99.9 percent methane but volume that won't be the actual concentration you mean and again the performance for those machines are in publication 1684 and some things that just that I pick up on a little bit is when you're doing those surface emissions there's lots of data points on we often see reporting by exceedance or acceptance and that's not ideal because although it's important to see where the exceedances are what you want is you want the total picture because the total picture gives you the patterns so you might have an area over here that's not exceeding but there's clearly higher emissions here than anywhere else again thinking about that feedback from your monitoring to your management that's telling you that something's going on over there that needs your attention and so to get all the data data logos are typically used these days because it's a lot easier and you can overlay that on google maps images various images that's by far the best way to do it that's how EPA likes it that's how i like it as an auditors assistant because it's just all there you can go yeah great i know exactly what's happening um for hang on you've gone ahead there mate uh yep so for buildings and subsurface services i wanted to just pick up on it being methane only because sometimes still cco2 being picked up in those areas and there's a few reasons why you don't do that most most the biggest one is there's a lack of equipment that can do that really well as going in doing it portable and periodically so but for buildings in particular it's really important to make sure that you're using a tdl or a huberg i'm not an fid because of the interference you can get from non-methane uh sources in those areas so if you go if you go into it i don't know a canteen and people are frying up some bacon there's people smoking nearby that sort of stuff the frd is going to pick up and burn those things and you're going to it's you're going to read that as methane because it doesn't speciate it and also please make sure it's not an extractive landfill gas analyzer that's used for those areas again use epa publication 1684 um and there are alternative instruments for co2 um there might be instances where you need to use co2 but that's where you need some specialist advice so don't just go in there with an extractive analyzer because there's reasons why it's not going to do the right job for you all right thanks Richard um so some of the bits there some of the pitfalls um this came up a lot when i was a regulator the first dot point there which is compliance with the better gas action levels which are reproduced on the screen for you they you have an obligation under your license or your pc phone or whatever you've got from epa to meet those and you can't make that obligation go away by a risk assessment that's a separate thing so you have to take all reasonable steps to meet those gas action levels and that's what epa should be regulating you on but if you have an actual risk that remains after that that's where you go into a landfill gas risk assessment so the way to think about it is those gas action levels are blinds to the actual risk they apply whether you've got a house five meters away or you're in the middle of nowhere you still want to meet them and that's because that's a really conservative way of doing it because of that catastrophic result of gas migration occurring um i've said please please please because it's something that we see all the time do feel calibrations also known as bump checks of your gas monitoring instruments because um we see lots of really really weird results and we never whenever provided with any evidence that those calibrations have been done and we think that's part of the reason why so you'll receive it if you hire it calibrated but it can drift in between you picking it up and using it so the bump cal is really quick just to go is it still reading what i expect and you're good and this is another one gas monitoring um when you're looking at the barometric conditions i often see reports where the barometric conditions are reported at the time of the monitoring so monitoring start monitoring end um that that's that you need to record that but what i need to know and what anyone doing gas risk assessments need to know um is what was happening to the pressure before you did the monitoring because there's a lag in response between the barometric pressure changing and the ground gas regime changing um so that needs to be captured need to understand whether it was static rising falling and my advice is about eight to twelve hours before is what you need the information for easily obtainable from bomb just needs to be considered uh uh when you're reporting that and that's in epa 1684 that guidance as well um the ball monitoring methodology is another one that gets a bit sideways um so this is you know the the perimeter monitoring boards around the edge of the landfill in in the geology um the order is there relative pressure first then flow and then you gas concentrations because that provides the least disturbance to the ground gas regime and that's because the relative pressure is a transducer there's no there's no gas movement it's just the gas pressing on it flow does actually open the ball and allows it to go into a micro orifice plate and then number three the gas concentrations that's when you cause disturbance because you're physically pumping the ball now imagine you did that first imagine you pump the ball first then you did the pressure then you did the flow you're reading the result if you aspirating the ball not the natural ground gas regime or the influence on that regime from the landfill gas moving through it so that's really important uh and that's covered off in 1684 as well um this one sounds really obvious but the amount of times I think it's not done um that the units give you the results in real time so as they come in and have a look at them does it make sense um if it doesn't make sense question why um so what we'll often see is we'll see results reported from from doors uh with you know 24 26 28 plant oxygen uh which is is impossible in in the in the natural environment so had you been looking at screen you go hang on I think I've got a calibration issue so just keep an eye on it while it's while it's doing its thing and see if it's okay um ball league tests are a bit of a passion of mine as well um I want to see that they've been done on installation but I just wonder about this is just out of my head you know whether this should be periodically done thereafter if certainly if there's any had been any damage to the ball but um sometimes you'll see results that you had landfill gas landfill gas landfill gas then it goes atmosphere and then it just continues to be atmosphere and I'm just thinking hmm don't think that's real I think you've got a leak in the door you know so if we were picking that up with with somewhat regular leak tests then you'd find those those those issues so just yeah just a few things that have come along um sorry Richard you're good to go there um this is landfill gas is by far the heaviest bit of this whole thing by the way because it's the most I suppose the most complex area and it's the newest area so to speak particularly when in Victoria if you consider groundwater there's been groundwater audits in bit forever so people are pretty well schooled in that um now bring up bore spacings because it comes up all the time count all the time in EPA comes up all the time now as an auditors assistant and my advice is use what's in Beppen it's recommended spacing so you can have an argument about it you can have a discussion about it whatever uh but like if you start there it's a good place to start um and the other thing to bear in mind with that is if you've already got gas action levels being exceeded in your existing bores it's going to be a pretty hard sell to the regulator that you don't need to meet those recommended spacings so just think about what's what's happening with uh with those um uh personal favourite of mine background carbon dioxide please don't use the perimeter monitoring bores to to determine that um you're using the very things that are there to try and find landfill gas to try and say that the CO2 that you've got in them is not landfill gas right so you I think you can probably see the problem there right so it's a minimum of two bores that are offsite or sufficiently distant from the waste mass so that they are not expected to be influenced by landfill gas but they're still representative of the strata that your uh your primitive bores are sunk into and you can compare the bologna to you know are they in vaguely similar stuff or the same stuff great if they are um once um you're so you're doing a background CO2 assessment you've established what that source is please say what it is in the report um again sounds really basic right but it doesn't happen a lot um someone will go I've done the assessment here's my numbers and background CO2 is eight thanks very much love personally kiss right and you just like you haven't told me what it is right so is it biochemical is it is it dissolution of CO2 from limestone strata right you know you need to know what these things are you can't just say I've done some numbers and some some statistics and therefore it's it's a thing um now mr. Mr. Stuart Thurlow who is my uh my off-sider and my boss uh who uh and oh we constantly go around the ringer about this one um but groundwater bores are for groundwater monitoring and landfill gas bores are for landfill gas monitoring please don't mix them up um especially don't use groundwater bores for landfill gas monitoring now because Stuart's not not here and he can't speak for himself um there are some very limited circumstances where you can do it um but they are very limited and I don't go into them in this presentation for that reason so my view is just don't do it um but if you if you absolutely do have to do it then have a really good think about it and consider these things right and the reason why is a groundwater ball is for measuring groundwater right the monitoring groundwater so its screen's going to be in where the aquifer is it's not going to be in the unsaturated zone where landfill gas is expected to move so if you've got it long screened solid casing through the exact bit where gas is going to occur you're going to get a false negative gas could be moving outside of that it's not going to go in the bore because the perforated sections are submerged in groundwater and also if you um if you get a groundwater movement in that bore because it's quite its feet wet because it's a groundwater bore that can induce that that can induce um a a flow on the monitor because the piston effects the groundwater comes up it causes that gas to move in the bore so you get false pressure increases and decreases if it goes down uh and false flows that have got absolutely nothing to do with gas generation and the assumption is if you get pressure and flow in the strata that it's from gas moving and generating through it when it's not it's groundwater movement um particularly within the bore that's not to say the piston effect isn't real in the geology but if it is real you'll pick it up in the landfill gas bore um and the other concern I've got is uh groundwater bores may or may not meet the uh specification for a gas monitoring bore that's in table b3 of of Beppham um and my personal favorite don't purge landfill gas monitoring bores right now that by that I don't mean you know don't turn the pump on and pull the gas out of it that's what you need to do right but what I've seen is um uh people connecting the analyzer and purging it first um you know applying a groundwater methodology effectively to a landfill gas bore uh and so they and it's normally I did three three bore volumes and it's great when there's like a 50 meter deep bore or something they pull you know nine million litres out of it and then go oh I didn't find any landfill gas they go oh did you not yes because you pulled it all out before you actually turned the analyzer on properly um so when you hear about purging particularly in vapor bores and that sort of stuff what it's talking about I think it's CRC care publication 23 it actually says bore purge and but later on it says line purge and that's exactly what it means it means get the air out of the the tubing of the instrument not purging the bore itself so just watch out for that one okay thanks Richard in fact sorry could you just go back one because I forgot to reference diagram have a look at that pitch on the right um you can see mw09 and then you can see mw13 right so um what you've got that's the landfill in pink to the left so if imagine you've got gas moving out of that landfill to the right and you've got mw09 you can see that's perforated that's going to pick up the gas it's going to go through that but if you were to undertake monitoring from mw13 it's way below the base of the landfill and that's solid casing above that perforated section so the gas is not going to go into that port or that picture there just perfectly illustrates that point that that I made earlier and I forgot to talk to it when we were actually in that section all right thanks Richard lead tech monitoring another personal favorite of mine how many people have come home covered in lead tech many many many times um so not huge amounts to say on this but um just a few things that come to mind so um consider um you know you want to get the geochemistry of the leachate across the site so take samples from as many samples as there are um to get that cross section to be representative of the site particularly where you've got a cell that might have taken a vastly different waste type to um to the rest of cells on the site so let's imagine cell one only ever took solid nert waste and every other one from there on took potential waste you're going to get some differences in those geochemistries um there are a couple of sites of course that we know about old school ones that might have taken some real old school hazardous stuff liquid hazardous stuff you know that's going to have vastly different leachate to the to when uh it had a newer permitted cell so just just think about that um our cmp's normally include something of leachate from the dam or the pond or the goon whatever you want to call it um that's that's fine and that needs to happen but just consider it's not going to be necessarily representative of the true leachate geochemistry because of that oxidation that exposure to air especially if it's aggressively aerated so it's needed but you'd still need the samples from the sump as well to have a look at what's happening with the with this composition um so then when you're doing the level measurements so not the samples um that's typically done with the dip meat where there's a picture of one of those on the right um but you can use pressure transducers as well um I don't see too many of those most people tend to go with the the dip meat still I think it's forcing publicity um but you come unstuck with those when you've got a side riser uh because you can't you can't use that vertical dip meter method uh you've got to use a sled uh on a probe uh and then do some trigonometry um or you can go down that pressure transducer route as well um so just just a few things with with leachate monitoring um and I think I've mentioned yes one next slide uh now you you're good Richard um I'll get to that picture in a minute um so with leachate something in particular it's really important because we we look at things in relative levels um that uh that they're surveyed and surveyed uh relatively regularly especially in the first five years because in that first five years you're going to get a lot of settlement of the waste and even though these these things are built up from the waste they tend to go you know a bit sideways as as the as the waste settles um so you have a level change so um that survey is really really important to get an accurate leachate dip um when you uh when you did it um uh another personal favorite mine um don't dip leachate something when the pumps in operation because you're not reading the standard liquid level in the waste you're reading in cone of depression you're reading this all right um whereas what you want you want to be reading that but you're reading what's the base of my hands here uh because the you know the the pumping will create a sort of funnel effect um so the the general advice I give is is just if you have to dip that something is to is to uh suspend the pump on it for 24 to 48 hours um which one you choose you know I'd say be guided by your compaction if you're getting really good compaction ratios 48 hours uh if you're not getting great compaction because the waste I've taken in you might get away with 24 and that's just because the recharge to the sum before you get that true level representation um some of the other stuff um that is an alternative uh if you wanted to keep pumping uh is to use dedicated leachate um monitoring bores that aren't used for pumping so a lot smaller diameter um that are remote from from the sum so you can keep pumping but then you can dip these things that are sufficiently remote from the something that will give you the standing liquid level in the waste while you're still pumping uh at the sum uh if you've got a real objection to to suspending the uh the pumps uh another alternative uh is to use the gas wells so you've got if you've got a site with active gas extraction you've got you've got you know little insights into the uh the liquid level all the way across the landfill if you can dip the uh dip the gas wells but importantly uh one thing I've written out in the second one I haven't consulted the drill log of that well first you know how deep it is because if it's above where your compliance level is there's no use secondarily uh you know popping open a gas well is um not too much of a bad thing but you definitely want to be having a chat with the gas system operator first normally it's just a little dip port you just screw it off and drop the meter in get your number and and pull out but um it will bring a bit of air in so if they're quite sensitive to that just have a chat with it first okay oh sorry I didn't do the picture today um so that was um one for mild EPA days uh just for reference that was uh that is not a leachate sample um that was from groundwater um but obviously had had leachate in it and I recall the conversation that I explained to that duty holder that they might have the groundwater contamination problem and a leachate management problem and I was told I was unreasonable I thought I was fairly reasonable given it looks like a Russian imperial staffed okay on to groundwater so um EPA talks to publication 668 and rightly so it's still a good uh publication um and that states uh you need a minimum of three groundwater bores to determine a hydraulic gradient um now that's fine right um so if you imagine you've got a bore here and you've got a bore there that one's reading higher than that one okay your gradient might be that way but if you've got a bore over here that's even lower again now your gradient's going that way um so that's good three I think is okay but in reality you do need more because groundwater systems are rarely that simple um so um and and you certainly need more than three for a representative network to actually obtain groundwater chemistry samples as well um now I'm going to link back to that CSM right at the start now um with that radial flow situation so you've got groundwater go a flow going that way and you've got radial flow of leachate going this way um on that picture uh the right and this is one of our client sites but I've sanitized it so only they should know which one of these if any of them are on um I'll look at bore um tp l1 up there uh where it says online cell one uh and you've got um where's the other one um you've got tp l2 as well um so the hydraulic gradient here is uh north to south so this bores are strictly um considered uh up hydraulic gradient but they're proximity to the waste mass there means that they're at risk of that radial outflow situation particularly where you've got groundwater flows that are very very low which is a relatively common you know like particularly in bass spots and that's what's for um if you've got low transmissivity you've got a real risk that you've got uh leachate that's actually going to move out in all directions so you need groundwater bores that are up on our up hydraulic gradient that's sufficiently far away that they're not going to be influenced by that it's particularly pronounced where your leachate level is above your your groundwater level which it it typically will be especially in new sites because of that two minute separation that's required so if you look now look right up to the very top of the diagram you've got epaul 8 that's a spot on location uh for uh a not hydraulic gradient bore um you're not going to get any influence of uh of leachate at that proximity there um so that is what i was getting at um and that's because diffusion will uh will will move things against the hydraulic gradient unless the water's just ripping through there and now why that's important is um we look for change don't we we look is the upgrading condition similar to the downgraded condition or are the different on the assumption that the upgraded will be clean and the downgraded might have a few leachate indicators in it well if you're upgrading scott leachate indicator indicators in it any downgraded scott leachate indicators in it but you don't actually understand that properly all you're going to look at is oh there's no real change between the up and the down therefore everything's okay so the key thing here is to first evaluate the location of those bores but then secondarily have a look for key leachate indicators when you are evaluating your monitoring data so i'll put a couple of the ones i use up there um so bicarbonate real real key one ammonia real key one um iron and manganese together um another key one i look for together is potassium and an ammonia because they don't exist naturally elevated uh in any natural system um uh but you've got to look at those relative sorry they don't don't know it exists really um elevated together uh in any natural system uh but they need to be looked at relative to your calcium, magnesium as well which are naturally occurring so if you're seeing those trends across that hydraulic gradient they look the same with that stuff and you've got bores quite close or hydraulic gradient that's what's going on you've got leachate going in all directions um and linking into that is that that leachate to natural ratio is is an important measure as well but it's but you can only use that when you thoroughly understand the background aquifer chemistry as well and the key thing to that is that you've got ball locations that are representative of the background chemistry so if they're too close to the waist you see the problem right so that's the main issues that i've come across with there with groundwater all right thanks Richard um so uh last bit from me uh is just about monitoring frequency because this this comes up a lot particularly as an auditors assistant as well how often do we need to monitor what um so i don't think it's that commonly known but but EPA is slant or licensing guidelines so publication 1323 uh requires a minimum frequency of quarterly monitoring for for everything right so just i hope you know start there um and uh then evaluate what you've what you've got so if you're you've got a you know you've had an audit period or two that shows things uh a static um you can have a conversation about um whether or not you could reduce that that that frequency um or do less monitoring uh conversely if you've got things getting worse uh then um you might have to increase it right so um start quarterly evaluate what you've got uh and then have that conversation from there including with the EPA as well um and on landfill gas there's an increased interest and rightly so and a lot of use of and i fully support it of continuous landfill gas monitoring it provides a lot of um uh it provides a lot of advantages over the periodic stuff um most key to that is a huge amount of data resolution compared to going out there you know once in a month for example with a j5 000 um and it's going to pick up all those peaks and troughs those highs and lows in that ground gas regime and and now you know with things like the um you know the ambient gas flux uh you get flowing included as well so continuous gas concentrations relative pressure and flow everything you need for developing your conceptual site model um the the what you can have with periodic monitoring that can sort of trip you up and i use those frequency diagrams on the right hand side on purpose here uh is if you happen to go out with a an analyzer so not using a continuous monitoring just going out periodically uh and only pick um the peaks or only pick the troughs you're either going to always pick the low results or the high results completely unbeknown to you so you could uh over or underestimate the risk um equally you could always be reporting non-compliance to EPA when there were points where there was compliance and also and this might be a advantage but you can never call it uh reporting compliance when there's actually non-compliance that occur in between when you were there um but from the ground gas risk point of view it's particularly important in the landfill gas risk because that continuous stuff is really really helpful for us capturing meeting that uh worst credible scenario on the barometric conditions so if you've got i don't know you've had a a gas flux in in a couple of boards for i don't know a month um recording every minute think about the size of that data set and the chances that it will actually capture um your worst credible barometric drop probably probably highly likely and contrast that with going out there maybe once or twice with a more than gas monitor during that month period the chance of you hitting that is is not very high um okay that's me i'll um hand over to uh to richard thanks very much nick that was uh fantastic and very comprehensive uh so this part of the presentation is just more about um how to do some of that monitoring you know what are the what's the instrumentation you've certainly heard from nick uh some of the pitfalls particularly around spot measurement data um this emphasis on this is really around continuous monitoring um why the emphasis on continuous i see the shift in regulation towards uh operational efficiency and improvement there to prevent pollution in the first place um tying a lot more into continuous monitoring than spot monitoring why because that's how you keep an arm whether things are working or not nothing it's a great shift in the regulations to be honest um we will have a lot less problems with landfills if they are compliant and we'll have a lot less problems with achieving compliance if you know how your various systems are working like landfill gas extraction leach out extraction etc so i've just made a bit of a list there of the various sorts of things that can be monitored continuously and uh there's quite a lot right and all of these technologies are very well established um even litter we've set up an automated monitoring system for litter at one stage it's a bit of an outlaw but certainly typically we get involved a lot with monitoring leachate you know the quantities of leachate that are on the site are we meeting the compliance levels above our liners are the pumping systems working what volumes of leachate are coming out are the pumps working full stop right so often uh you can have some sites where pumps haven't been working for quite a while and they're they're closed sites and no one knows so these sorts of things very important another one i'd just like to bring your attention to is cap performance so we're getting involved more with uh lysimeters which are used on transpiration caps so for those of you who aren't aware of transpiration caps an alternative to a fully designed cap with a membrane etc on it um compact you know we've got compacted clay plastic liner etc um a a transpiration cap is based on having a soil layer that's supporting vegetation that will suck up any moisture that rains on that soil so you need to have a really close understanding of the performance of the transpiration or the evapotranspiration that's occurring so we've been involved uh more and more with those sorts of lysimeters so how to measure such things and what are the parameters um typically when you're dealing with leachate pumping and collection systems you're looking at levels and flows um and levels are typically dealt with using things like pressure transducers and bubblers um ground gas monitoring there are a couple of really good options and that's one area that hydrogen has spent a fair bit of time working in where you can pick up your continuous ground gas concentrations so that gas that nick was referring to moving through the geology so through the fractures and through the the pore spaces in the soil can be detected but it does vary a lot and at one stage we did a bit of a review and a presentation on the variance in concentrations that you see versus the likelihood of picking it up based on the eba's required frequency and we found there was about a 75 percent chance of something on that particular data set of actually missing an exceedance so um whilst we can rely on uh some of these standards as a starting point when you get the data like that um it really begs the question well are we doing enough monitoring and that's the strength of continuous is that you are doing enough um groundwater level monitoring systems these are important in terms of looking at your hydraulic gradients around the site and also for determining your flow regimes generally so often that sort of groundwater level data is collected using either dip meters if it's spot measurement or using things like pressure transducers these days you can collect that data and you can automate the contouring of that data obviously uh when you're contouring it's a bit like using a surfer package or what's called surfer um doesn't always take into account all that geology uh considerations but it does provide you with a bit of a snapshot of how things are changing which is always useful water quality monitoring we get involved a lot with that around particularly the sort of surface water end of things and around trade waste discharge so when you're trade waste license you have to meet certain requirements and your trade waste regulator will require you to show proof that your meeting knows and real-time sensors installed in line is one way to do that um in terms of storm water and discharging of storm water often you need to prove what you always need to prove that the water quality is okay before you discharge and that can be a cheaper sensors or with grab samples. In terms of air quality that comes up because landfills are dusty sites they also produce litter they also have surface air emissions and we've been involved in monitoring all sorts of weird and wonderful emissions from landfills sometimes there'll be a subsurface fire and they're worried about potential emissions being generated from that as well so you need to be thinking about your air emissions as well as your subsurface gas migration pathways as Nick said gas is a big part of managing landfills um noise monitoring sometimes around an operational area you know these days landfills are often reasonably close to urban settings and there can be problems there weather stations are very important around things like those transpiration caps that I mentioned and sometimes it's good to have high definition cameras just to keep an eye on your operations so just briefly into those a few examples so some pictures here of continuous ground gas monitors so the two most common ones that we utilize and I think they're the most common in the industry there's a thing called the ambi sense which that's mounted on a pole there it could be mounted on top of your bore hole and it tends to have a quick connect fitting to the top of your well and you can program to take quite frequent measurements using that and those results are to limited back just a word of caution these sorts of devices typically have a bunch of calibration algorithms and conversions that occur outside of the instruments know up in the cloud and uh some people will record those the data just within the unit and think they've got the appropriate uh reading but if it hasn't had those conversions then you don't have good data so that was one little looky error we came up with early on so I'd advise you not to go down that path typically when we're renting these sorts of units out we provide these um and install them so we'll do all of that setup rather than having those occur on the right is the uh gas clamp and that was the first ever continuous ground gas monitor uh in the in the world and that was a UK invention and uh was taken over and it's gone on quite a journey the differences between these is you can use the gas clamp in an intrinsically safe environment okay so it can't it's it's certified as suitable for intrinsically safe conditions when's that important not so much with landfills more with things like refinery sites and that sort of thing but keep that in mind both of these produce continuous data both can be hooked up to telemetry if you hook up the gas clamp to telemetry it's no longer intrinsically safe so just be aware of that one how am I going for time nick spray I was on mute and we passed one so we've got 10 minutes to be a lot of time left okay I'll skip over these for continuous ground water and leachate level monitoring a couple of options that have been successful that we've deployed in the landfills you heard Nick mention using pressure transducers on inclined sumps we've also used bubbler tubes let this device on the right is a bubbler it measures uh level continuously as well and there's a telemetry unit attached to that the advantage of bubblers is you have no electronics down the sump right so this thing this photo on the right here with the the tube connected up to it that is a landfill sump it's sealed because it's also collecting some gas okay so on quite a few sumps these days you are have you've got multiple purposes of those sumps there are some things to be aware of pressure can build up in those can affect various readings that you might be wanting to be taken down there so I like bubblers they're good they're a bit more expensive than pressure transducers but they're very low maintenance okay you don't have any instrumentation in contact with the leachate just to chew so keep that one in mind okay I'll skip over these other than to say obviously there's continuous monitors that nice picture with the sunset there shows two forms of technology achieving the same sort of thing so you've got your traditional dust deposition gauge but you've also got a continuous nephelometer there providing continuous landfill gas data um this just as case study was about monitoring operational uh side of a closed landfill so this is a site that hydroterra commissioned a landfill leachate pumping system um this was all solar powered and it had telemetry set up to continuously monitor those pumps and those levels so there's a lot you can do these days in terms of automating these sites and for having alarm systems to keep you informed 24 seven about the operation of these sites so without further ado we will move to a summation which is landfills can have significant impacts on the environment Nick certainly made us aware of those exploding houses and things like that poor monitoring data is by far the number one issue encountered as a regulator and auditors assistant so Nick wants you all to get better at providing him with less grief when he's doing his role and I thought it was a really good summary of some of the errors that occur with collecting data there are strong regulations in place and I think Nick's provided a great uh reference for you to look at what is a great starting point for making sure you're doing enough okay um and finally I sort of covered off on there are many well established monitoring technologies both for spot measurement and continuous now over to our favorite part of things Q&A um so yeah the monument ones um the the way I've seen that done I've only ever seen it done uh uh done once um is um it's the same way as um as what you suggested there so he said almost all guidance refers back to testing a shroud uh on the on the gadget covers it's doing the same the same thing uh but just creating a shroud around the monument if you have a look at I'm pretty sure there's a picture of that being done in um in that CRC care uh technical report 23 that that I mentioned the key thing is to make sure that you've got a good seal around it obviously um and um the one thing I didn't cover off on in uh the in the presentation I forgot while I was talking uh was I I like to use the the 10% threshold uh that's also in CRC care 23 as well which is if you've got 10% of the concentration of the gas you introduced in the shroud in the bore uh then actually threshold for for having a leak um so um I hope that answers that question it's the real key thing it there's no real hard and fast way you know a lot of people uh do that using a variety of methods from a great big plastic cover with sandbags and all sorts of stuff to to to make that seal um and another thing that I'm seeing for simplicity that helps as well as people using isopropyl alcohol as you trace uh rather than uh helium um because uh just for the simplicity of doing that um if that's not an answer to your question um my contact details at the end uh give me an email and we'll we'll we'll talk about from there um next one is from Liz uh if you have two background co2 bores uh how do you apply of sound it's moving on me there uh how do you apply the results to your primitive bores uh use the results and to or calculate uh the the average so um what you would do with that is um if you look at epa publication 1684 I've covered off on that in there uh it links to a recommended statistical technique uh for effectively accounting for outliers and generating a dataset per bore uh and then uh that is how you apply that to your to your general background for your um for your landfill site if you had two bores um uh and you and you've got two different results uh then uh I would be I'd imagine those I would imagine to hope those two bore results would be relatively close to each other so there probably wouldn't be too much of a need to to do a mean on them uh if you had two dramatically different results um that would be okay and if you worked out why they were different and explained it satisfactorily then you could do a mean on those as long as uh you were really happy that they were they were real results um so if you had one result that was from was biological uh respiration of uh of bogs in the soil versus one that was was dissolution of co2 from some sort of carrier strata they're both relevant but you wouldn't necessarily do a mean on those two uh because you got sort of two different sources unless you were happy with the bore logs around the site that the bore that the strata that was generating that co2 was in place around your landfill as well um not too common but that that that's how I go about doing that um next one is anonymous uh if of a landfill gas bore is found not securely fitted on the bore um or attempting to attach jay for five thousand to get a gas measurement what is the likelihood of the results being skewed I would say 100 you need the bore to be sealed to atmosphere as best as possible because you want to be reading the the ground gas regime in the response zone of the bore as undisturbed as possible you're never going to get zero communication with atmosphere because of biometric pumping unless it's really really deep but yeah if you've got a crack in the bore casing you've got a loose cap and leave that bore uh off for that day resecure the cap and pick it up the next time record that in your field sheets as to why you didn't take the result um an alternative could be you could take the result anyway but note the fact that the cap was uh was loose I think either of those are okay as long as you make the client and the regulator and the auditor whoever aware of what you found uh Richard that one's for you this is how Richard will attendees get a copy of the presentation uh yes they will uh that that's accessible on our website so we'll uh send you an email with a link and whoops I want from bryden hi bryden uh what lateral leachate flow or upgraded flow how far do you see this occurring particularly doing through leachate in the landfill um that is really highly site specific um there's so many factors at play there um you know transmissivity of the upper permeability of the geology strength of the leachate uh determinants in the leachate uh whether or not you can lose those materials through some sort of a tenetive process on the way from the landfill to the bore I don't think I can give you a sort of hard and fast answer you'd have to look at all of the factors in the csm to answer that site site specifically uh next one from ross uh there's increasing pressure on reducing landfill buffers uh clearance zones uh what's been my experience for reducing these clearance zones based on conservatively derived technical merits or there always be a policy that simply prohibits and defers to a generic 500 meter no-go zone yeah that's a great question um I think the first point to note there is that the purpose of a buffer is not to sanitize that land uh it's effectively a flag in the planning system that says if you want to do something within 500 meters uh or 200 meters of the landfill depending on what type of landfill it is you're talking about uh you need to undertake appropriate assessments to work out if that risk is acceptable uh and that's driven by the responsible authority not not EPA although EPA is a referral authority um but my personal view on it is that um if a risk assessment is done well it's done well um the times when that is extremely difficult I would say impossible is when you've got an operating landfill uh unless all the new cells are moving away from where you are um because the problem you've got is um you cannot future predict all of the variables and the performance of those cells that could lead to a landfill gas migration problem so if you're next to a cell that's not been filled that long ago it's got it's got a cap on it's got a gas extraction system and everything seems to be okay okay good um but it's okay it's okay when you looked at it or it's okay for the period that you looked at it but if that operator drops the ball floods the gas wells with leachate someone um just drops the ball on on the field balancing or whatever uh then you've now got a change in your source which changes the magnitude of your risk so um I wouldn't go near it for operating landfills but for closed landfills it's absolutely a thing because you don't expect too much of a material change uh in the nature of the source um but that is based upon how old that closed landfill is you know so if it's 50 years old and there's not a lot going on yet all right but if it's closed it's been close for two weeks you know it's not that much different to one that is the distilled operating um so a good question that comes up a lot and um that view I've given there uh is a view I've given multiple times in the witness boxes an expert witness and it has been accepted so um that view around you know don't try this with operating ones because there's too many variables that you can't compute um next one is a repeat of the can we have a copy which we know the answer to oops I've got time now um one for me for continuous land for gas monitoring what is it suggested suggested ratio between continuous monitoring and periodic monitoring um I wouldn't say that there is one um I'd probably advise against chopping and changing while you're doing one um or do you mean if you've got to say I'm gonna sorry I'm gonna pursue I may can't answer it I'm gonna assume by that you mean let's say you had 10 bores um would you put your on continuous monitors and do periodic monitoring for um for the rest um assuming I'm answering your question right I'll just keep going with it um then um that's that's relatively common and what I would do is select the bores uh for continuous monitoring that are the ones that show probably the the highest risk uh based upon the results or the proximity to the receptor that you're concerned about uh or maybe the most variance you know so if they're all over the place you've got 1% one day you've got 25% the next day you've got 60 next year somebody's going on there and that data resolution will really help you pick the teeth out of that as to as to what's occurring um so again um I wouldn't say there's a hard and fast ratio I would say be guarded by the dataset and the CSM and what you're trying to achieve in making that decision um Mark asked how do we measure smell uh you usually knows um not being facetious there um the the mark one knows uh has got uh what we are now about 180 000 years of evolution that's created that machine um so it's by far the best one uh in my my opinion um just need to make sure it's calibrated as well maybe um there are various electronic versions of noses emerging um I've sort of been around for about 15 years now um what what they struggle with is you need to identify the particular compound that's causing odor and then uh effectively make sure you've got a sensor that's aligned to detecting those particular compounds um but yeah certainly there's some research going on in Canada about 15 years ago and they were producing e noses and things like that um so you used them have you had a crack at a machine uh well not not really um had had distribution rights to the technology for a little while but it um wasn't applied so much in landfill but they do exist I suppose is the point I'm making yeah I saw one we played with one in the environment agency before I migrated to Australia and um it was pretty early technology we're going back a long while now and I know there were there were concerns about it at that time not being exactly as a as a as a nose calibrated with n butanol uh but um uh yeah okay cool um where we get to uh regional Queensland landfill gas is hardly monitored and no legacy landfills how many landfill gas monitoring boards is it due to the dry landfill aspect of the bore and the minimal waste qualities um okay first thing I'll probably want to associate queen of Queensland and dry in the same sentence it's um you don't other than maybe certain parts of the centre or maybe parts of northern territory you're going to find it hard to find an absolutely dry tomb landfill um my suggestion is if gas is hardly monitored and there aren't bores around that's probably due to either um a weak regulator or a insufficient guidance materials or and by the week I don't mean that as an insult I mean a regulator that might not have the the correct amount of resources to get out and do that stuff or maybe doesn't have the people with sufficient experience um I don't think it's because someone's gone out and evaluated and said this isn't the problem you haven't got to worry about it that's been my experience of being a regulator for two different regulatory bodies uh Nick just conscious of time I know you've got another meeting that you're meant to be at now yeah I'll just smash these last two that's right with you and then I'll yeah that's fine that's part of that during time but I don't want to let anybody down um the last two and then I'll I'll vacate and thank everyone for your time um so based on my experience kind of represent uh provide some standard background concentrations for CO2 um yeah okay so uh look the place to go for that is uh Syria C665 there's a table in that document um that gives typical background background concentrations of CO2 and their source their sources as well and it does it does uh all sorts of things in there does methane does h2s and and a bunch of the bits so that's where I'd start to uh I'd start with that um and um it's look if you're getting above 10% CO2 um it's it's not normally background on its own uh so have a read of that table uh because it tends to max out uh with uh uh you know biological oxidation of of organic matter and soils at 10% and that's got to be within you know alluvial colluvial soils you know if you've got something that's not got a lot of organic matter in you know sand for example you're not going to get that so that's where that's where I'd go to for that um is the frequency of bump testing in any guidance uh yes it is I wrote it into EPA 1684 and it's every time you do it um uh so the frequency is if you're going out to site uh you should bump test every single time you're you're you're going out um to to do it uh we'll take you um not depending on how many machines you've got whether with a um a tdl or a huberg it's going to take you 30 seconds uh with a j 5000 gfm 436 that's that's going to take maybe about five minutes something like that so do it every time if you're particularly concerned my advice is particularly if you take your samples that might be a challenge legally um you do before and after so you pick up the drift from the calibration to when you commence monitoring and you pick up the drift between when you started monitoring or when you finish monitoring um do both of those and record it all um and that's it from what I can see for questions um all right well I might just um say thank you very much Nick that was a fantastic presentation really um appreciate your time today I think uh it shows someone who's very close to the coalface and used to dealing with questions related to landfills everything in landfill um and monitoring in particular so great job and many many things for that and um feel free to shoot any other inquiries through to either Nick or myself by email and we'll do our best to um come back to you yeah thanks very much everyone for it really thanks and thanks for coming along see you later see you bye thanks