So, welcome everyone for our latest Hydrotera webinar. Many thanks for joining us today, it's great to see so many people turning out. Today's topic is on low-flow pneumatic pump selection for groundwater sampling applications. It's going to cover selection criteria, setup deployment, and we've got a video from one of our key suppliers, a technical specialist there to run through the various pneumatic pump options that they have as well. So, before we get started, just a little bit of a background on myself and Joe, who's the presenter of the video. So, in my background, I'm the founder of Hydrotera, but before starting Hydrotera, I worked in consulting like many of the people who are on this call today. I'm a hydrogeologist by training, and I've done quite a lot of work looking at monitoring options for various companies, including evaluating sampling technologies and a lot around low-flow pumps. So, I thought I'd share this one today, and it's great to be here with you. As I mentioned, Joe Revelle from Solanced is a specialist around low-flow pump technologies based in Solanced. Solanced is a company in Canada who make a range of monitoring and sampling equipment, originally founded by a hydrogeologist similar to myself at about 20 years older than me. So, looking forward to the knowledge that the suppliers bring a certainly great depth of knowledge in various suppliers, and that's something that Hydrotera really has the advantage of levering off in providing advice. So, we love to get questions and answers. Well, we love to get questions, and then I'll provide the answers. So, please use the Q&A button, and then I will endeavour to answer your questions. If I don't know the answer, I will find out from some of my colleagues and come back to you in emails, post the webinar. So, you do that by using the Q&A button there. Why does Hydrotera host these webinars? Well, we believe in sharing of knowledge, and I think right now in the current environment, we've got a lot of people who have been working from home for the last two years. It's even more important to be sharing our knowledge, to build the depth of knowledge in the environmental consulting sector in particular. So, these webinars, these 101 series are really targeted at people who are using monitoring equipment, whether it's sampling or sensors, etc., to provide you with awareness of what to use when, but also what technologies are out there. We also believe in facilitating education. So, we're hoping that there's some undergrads and the like who are in the audience, as well as maybe some older people who are interested for the same purpose of sharing knowledge on technology. Finally, we like to consider ourselves a bit of a leader in terms of thought leadership around environmental monitoring. Hydrotera's got a business strategy of becoming the marketplace for all things environmental monitoring, and we're heading well down that path. And obviously, a big part of that is to train up the industry. So, what are we covering off today in today's webinar? So, we're going to be first hearing from myself. I'm going to talk about some low-flow sampling considerations with a real emphasis on the pneumatic pumps. And then the second part of this is a video presentation from Solanced. It's a bit hard for them to be live, given there's about a 12-hour time difference. So, that's how we'll handle their presentation piece. And then Q&A will come back to myself and looking forward to getting lots of questions raised either by my presentation or by Solanced. So, firstly, with respect to pumps, I think it's important to remember some of the low-flow sampling considerations that we're needing to meet in order to make the right choice on whether or not to use a pneumatic pump in the first place. So, what are we trying to aim for? Well, EPA Publication 669, which is a Victorian EPA publication, provides a pretty good summary of what we need to be considering. So, the primary objective of any groundwater quality sampling is to produce groundwater samples that are representative of groundwater in the aquifer and will remain representative until analytical measurements are made. So, what does that really mean? Well, it means that the aquifer has a certain water quality and we stick a well down into that aquifer and we start collecting samples from that well. There's a whole lot of things that can change the water quality in that process and that can, in some instances, get to a point where the waterware sampling is no longer representative of what the actual water quality in the aquifer is. So, we try to minimise the potential for that change in water quality, but you can imagine the repercussions if you use the wrong sampling technology. For example, a classic example is sampling for volatiles. You have some volatile loss between collection and laboratory and you may say there is no contamination, but in the aquifer itself, there is a significant quantity. So, we need to be careful to adopt the best sampling for the application. So, we need to have some guidance. Some guidance is important for two reasons. It helps us to choose the best technical method, but it also helps protect us in terms of if we choose a method and there's a reference or a standard around that, then if someone questions whether you chose the right method in the future, you can reference that and say, well, we've adopted these particular guidelines, and that is typically sufficient protection for you if you're ever unlucky enough to be questioned in court about some work you've done. So, here's a selection of some groundwater sampling guidance. There is a lot of guidance out there. Most of it's pretty similar and tells the same story. I've always found publication 669 from EPA Victoria, great place to start, and I'd recommend that you all read it. It's readily available online. There are, however, some other ones there. Another one which is of interest if you're sampling really, really deep samples and you're worried about off-gassing is the GeoScience Australia guidance document, but there are not plenty of guidance documents out there, and you should really use them to develop up your standard operating procedures for sampling. So, what are the requirements that we're about to start talking about pneumatic pumps? What are the requirements that we're really looking at to fulfill? So, we need a pump that's going to allow us to undertake low flow purging until chemical equilibrium is reached. Low flow purging or micro purging involves minimal disturbance to the water column and the aquifer. This method removes only small volumes of water at a discrete depth within the bore. It's a few key words there, right? Small volumes, so that means it needs to be able to operate at low flow rates. Discrete depth means it needs to be justifiable that it is actually collecting it from a discrete depth. That can be a little bit contentious sometimes. So, these are things that, as you look at this video later in this presentation, you should think about, okay, how are they doing this? How are they achieving this? Low flow purging relies on the concept that ground water moves horizontally through the screened interval. That's the screened interval about well in a bore and that the formation water does not mix with the stagnant water above the screened interval. Okay, so I've got a little schematic in a minute just to show you what that all means. Easy to say, not always easy to technically justify. Okay, so we'll have a look at that in a second. Finally, low flow purging consists essentially of the following steps. The pump inlet is carefully and slowly placed in the middle or slightly above the middle of the screened interval at the point where the contaminant concentration is required. Now, we've got in brackets, dedicated pumps are ideal for low flow sampling. Well, they're ideal for minimizing the disturbance associated with deploying a pump and removing it. So, it's a bit of a no-brainer, really. You've got less disturbance if you leave the pump dedicated. Placement of the pump inlet too close to the bottom of the bore can cause increase in treatment of solids. So, you do tend to find solids built up in the base of your wells. Often, you have a sump section of a solid PVC at the bottom. Well, unslotted, I should say, at the bottom, which forms a bit of a sump for those sediments, which you shouldn't have your pump located in that, because it will end up getting clogged up with sediments. And that can cause problems with the ball valves that these pumps use. All right. So, just in the context of what I've just discussed, here's a schematic. We've grabbed this from that EPA publication, 669. What we've just said there is if you look at that, the spots on this schematic, that's the aquifer. Right. So, this could be fractured rock. In this case, I think they're trying to depict sand. But it's the layer that we're wanting to sample from. What's critical in this is that the well construction is suitable and isolated to that aquifer. Often, people will install wells and put slotted sections that cut across multiple aquifers. That's actually illegal, because it can spread contamination, but it also leads to results which are very difficult to interpret. In fact, what are they really? They're not very meaningful. So, groundwater sampling should be specific to a specific aquifer. And the slotted section of your monitoring well and how it's sealed is a big part of ensuring that that occurs. So, all of that needs to be done before we start putting our pneumatic pumps in the well. So, if you look at this schematic, you can see that there's a slotted section. That slotted section is where the water flows in and out of the well. In quite a few sites, water actually does flow through these wells in the same direction as groundwater flows. It really depends on the groundwater hydraulic gradient and the hydraulic conductivity of the aquifer, how quickly that water's flowing. But it is important to understand that water does move in and out of these screen intervals. And therefore, we can have the assumption that the water in that screen interval is the same as the water in the aquifer. What gets in the way of the party is that if you look at our standing water level, you see that little up-so-down triangle that depicts groundwater level. That level has air above it, right? That water within our casing and air will interact with our water in our well. And that can change the chemical composition. So, depending on the contaminants we're looking for, we need to be careful to consider that influence on the chemistry within that well. And we need to make an assumption that the water within that well hasn't been affected to the point where it's affected its representativeness. Now, to get around that, right? Or to deal with this fact that water quality could change, we tend to adopt protocols when we're doing groundwater sampling to ensure we've got some indicators that the water quality is representative. And that's what they call about sampling until parameters are stabilized. So, you measure your water quality at the surface. When your parameter is stabilized, it's assumed that it's stabilized because we're bringing water from that aquifer formation into the pump. And there's reasonable logic around that. So, that's what we're trying to achieve with our pneumatic pumps. There's a few things we need to decide upon. Okay, but before I move on to that, just keep in mind there are many types of low-flow pumps. Today's one is just about pneumatic pumps. So, other presentations we have to deal with other sorts of sampling pumps. Some things to consider when you're choosing a pneumatic pump are what is the well construction? A classic rookie error is going to site and finding that the well diameter is too narrow for your bladder pump or your double valve pump. And then you're in all sorts of trouble. Or sometimes it just fits and when you slide it down, the screened intervals just a little bit narrower than the casing and the pump gets stuck. That's very expensive for everybody. So, really make sure you understand as much as you can about your well construction before you go to sample it. You also need to know your depth.  You've got to take everything you need to site. It's impossible to keep coming back and forwards to site. So, think ahead. And you need to make sure you've got a tag line that can attach to the pump that's deep enough to go down to your sampling depth so you can retrieve that pump. Contaminant type's important. It's good to know before you go what you've got to sample. If it's got volatiles or if you're sampling from great depth, you need to think about volatile losses as the samples come up. All these systems we look at today still suffer from the issue of when you get the sample to the surface. It can degas. So, need to think about that. And there are various ways to do that. Some very specialised ones that we've worked with. If you're ever sampling something like that, just give us a call at Hydrotura. We'll give you some guidance. So, decisions to make. The type of pump to use. Whether to dedicate it or have it as portable. That sort of comes down to frequency of sampling and budgets. If you do have budget, you're better off to dedicate. You get higher quality samples. The materials you need. The decon procedures to use. And very importantly, if you're sampling a long one away, how long you can preserve your samples for before they're outside the holding tops. Just in sort of conclusion to my part of this publication, 6.6.1, that I mentioned earlier, has a nice little table in the back which talks about parameters that you may want to be sampling for and what sort of pump types you can use with those parameters. You'll see for bladder pumps, pneumatic pumps, that it's considered by EPA in this publication to be suitable for all of those particular types of contaminants listed. All right. I'd now like to hand over to Gleadsom who's going to activate the video and you'll learn a lot more about the specifics of two types of pneumatic pumps, double valve pumps and bladder pumps. And then I will see you in the Q&A. So I'll start off by doing a comparison between our bladder pumps and double valve pumps, our two pneumatic pump options. Then I'll be looking at deployment options. So in that section, I'll be talking about a portable versus a dedicated setup and all the components involved in those. Then I'll take all that information and apply it to real world situations. So I put together a few case studies where I'll give you the background of each of those particular applications and from that determine what's the most suitable or what I believe is the most suitable option to meet that particular requirement. So on the screen now you can see all of our different groundwater samplers that we have available. And as you know, today's focus and the next two will be focusing in on the pneumatic pumps. So that's in the center of the image you can see on your screen. But I just wanted to draw your attention to the other sampling devices we have available. So even though I'm focusing on pneumatic pumps, we do offer lots of other options. So if pneumatic pumps are something that might not fit into your needs, then we do have other pieces of equipment available. And you'll see one of the PDF handouts that I've included is our groundwater samplers chart. So that's just a chart form of everything you can see on the screen here. So it has all the sizes, depths they can be used to tubing examples, all of that. But on the screen here, these are just images of all of those. So we have our parasalted pumps, discrete interval samplers, inertial pumps, so foot valves. And then we have balers. So whether those are the stainless steel point source or just the plastic biodegradable bio balers. And you'll also notice I've included two images of our low pressure packers. You might be wondering why those are there. Well, those work in conjunction with a lot of our equipment, but more specifically in this particular case with our pneumatic pumps. So we do offer a pump to packer adapter for the pumps that I'm talking about today. And that allows you to sample below an isolated zone is one of the ways you can use the pump to packer adapter. So now on the screen, you can see a typical pneumatic pump setup. So I just want to go over the various components that make a complete setup. And then over the next two slides, I'll get into detail on each one of those components. So a pneumatic pump, what actually makes that pneumatic, it needs to have an air source or gas source to complete the operation to make it fully functional. So in the center, you can see we have a portable compressor. So you need that gas air source, so either a compressor or a two stage compressor, or if you're using more pressure than maybe a compressed cylinder. And obviously we have the pump for the sampling device, which is downhole. We have the electronic control unit that's used to regulate the flow between your gas source and your pump. And then we have the connection point at the surface, which then goes out to your sample bottle. So all of the pieces you can see on the screen there make up a complete pneumatic pump setup. So just keep that in mind that you need all of those components to have a fully functional system. Now solence pneumatic pumps, I'm going to talk about the two options we have available. But before I do that, I just want to step back a bit and get a thought process going of why you would actually want to use pneumatic pumps for your sampling needs. So one, they're a widely accepted sampling protocol. So a lot of the regulators worldwide call on pneumatic pumps for that type of sampling. So that's why we're focusing in on that, because it is so widely accepted worldwide. Also, if you think about using a baler or an inertial pump, when you're lowering that down into the well, maybe with an inertial pump, you're moving that up and down, you're creating a lot of turbulence in the well. So depending on the type of sampling you're doing, let's say you're sampling for VOCs, creating all that turbulence could then lead into off-gassing of those VOCs. So when you actually collect your sample, it's not fully representative of the true condition. So with the pneumatic pump, you lower that in place, you start your sampling, there's no moving pieces that affect the well. So you're not creating that turbulence that normally wouldn't be there. And also, if you think of using a submersible pump, you lower that down into the well, you turn the motor on, that motor is a heat source. So you're introducing heat that normally wouldn't be there within the column. So you're just making a condition that isn't naturally occurring. So with a pneumatic pump, there's no mechanical pieces that are down well. So you don't have that external heat source causing variations that normally wouldn't be there. So those are just a few things of, or reasons why you'd want to deploy or use a pneumatic pump. Obviously, there's a lot more than that, but those are kind of key, three key points of why you might want to use pneumatic pumps. So now jumping into the two options we have available. So we've got our 407 bladder pump and our 408 double valve pump. So on the left hand side of the screen, now you can see our 407 bladder pump. And on the right hand side, you can see our double valve pump. Now what makes these different? So just envision lowering the bladder pump down into the column of water. So as you're lowering that, the bladder is filling up with water and then water goes up the drive line to static or up the sample line to static. Then during the drive cycle, when you're pushing air from the surface down into the pump body, on the left hand side, you can see two orange arrows pointing in on the bladder. So what happens there? The bladder compresses, so squeezes together. And when that squeezes, the sample is pushed up the sample line to the surface. Then during your vent cycle, that pressure is released, the bladder fills back up. And then during the drive cycle, squeezes again. So that fluctuation of squeezing, releasing, squeezing, releasing is what causes the sample to rise to the surface. Now a bladder pump so widely accepted, mainly for that reason, because you have one dry side, one wet side. So you can say with 100% certainty that these drive gas has never come in contact with the sample inside the bladder. So you've got defensible data. When you're submitting that for analysis or submitting your results, you can say with 100% certainty the drive gas didn't come in contact. Now on the other side with the double valve pump, the way that that operates, again, just envision lowering the pump body down into the well. The body fills up with water and water goes up the drive line and the sample line all the way to static. Then during the drive cycle, water is pushed down through the drive line, through the pump body, up the sample line. During the vent cycle, water fills back into the body, goes back up the drive line. And then when you drive again, it pushes down through that U. And that series of falling out, going back, is what pushes your sample up to the surface. Now I don't want to get into any more detail on that, because Webinar 2 will get into more of the operation of the two pumps. So we'll explain that further. And in the meantime, if you are interested in learning a bit more about that, we have a couple YouTube videos that show the operating principles behind both pumps. Now in terms of the different configurations or options we have for each, our bladder pump is offered in two sizes. So our 1.66, which is in front of me here. So it's got a larger diameter on the pump body, which means it has a larger diameter bladder, which has a higher volume. So you've got more volume within the pump body compared to our second option, which is our one inch. So it's used for narrower applications, maybe a portable setup. It's more lightweight, so you don't have the larger pump to have the weight. Now you can use the larger pump and a portable setup as well, but the one inch is nice. It's easy to carry, fits into those smaller diameter wells. Then for the double valve pump, we again have the 1.66 inch. So from the outside, it looks the same. The only difference with the double valve on the inside, we don't have the bladder. And then we have a drop tube assembly instead of that bladder inside. So larger 1.66. And then we also offer the five eighths inch diameter. So for narrow applications, you can use this guy here, really lightweight, nice and portable. So it works out well and portable setup, which I'll discuss here shortly. Okay, so now moving into the actual deployment options. I've talked about pneumatic pumps, what they are, why you would use them, and then the options we have available. That's great, but how do we actually then deploy those into the field? So the first option I want to talk about is a portable setup. So this would be if you have all the equipment with you in your truck or your car, you take it out, drop it in the well, do your sampling, pull it all up, take it to your next well, or take it back to the office. So that would be a portable setup. So we start with our sampling device for a pump, which would be down well. And that would be any of the options I've just discussed. So I won't go into any more detail on that. Next piece, you're looking at your electronic control unit. So I mentioned at the beginning, this is used to regulate the flow between your gas source and the pump.  So we have our pressure regulator. So it's a turn gauge here that with the pressure gauge, you can see what you have set. Battery operated. So it runs off of four AA batteries. So those are easily obtained at any convenience store or gas station. So if you do need to have replacement batteries, they're easy to find. We have our quick connect fittings over here. So first, our driveline and sample line adapters. So you can make everything together with just your quick connect fittings. LCD screen up here. So that shows the particular settings that you set for that sampling event. Inside the memory, we've got presets, so low, medium and high flow settings. And you also have the ability of saving up to 99 user sites. So if you've got some number of wells, you can save the events. So when you show up next month, next year, you just select the name of that particular site. And you can see all of the parameters that were used in your previous sampling event. And then we have our manual override button over here. So that works out well. Let's say your batteries die at the end of the day and you still have some sampling to do, you're able to operate the control unit just by pressing the button to drive releasing to bed. So if you don't have replacement batteries, you can still use the control unit and do what you need to do. On the lid here, we put in the quick start guide. So that gives you an overview of how to set everything up. So if you're unfamiliar with operation or you've passed it to somebody who's unfamiliar with it, they have the quick start guide here to get them up and running. The unit comes with your driveline and sample line adapters. So again, quick connects on either end to meet everything up quickly. Now moving on to the next piece, we have our portable compressor. So as I mentioned earlier, a pneumatic pump does require a gas source. So we do offer our low flow portable compressor. So good for depth up to about 100 feet or 30 meters. And that comes down to the overall tank volume on the compressor. So if you are going deeper than that, a larger two stage or a compressed cylinder would be what you would use. But for any of your low flow shallower applications, this is a great option. So runs off of 12 volt batteries. So we have alligator clips here. So if you have a vehicle on site or 12 volt battery, you can just clip those on. It has auto on off. So when you get everything set up, you turn that on and you start sampling. It will come on when it needs to, shuts off when it doesn't need to inflate the or fill the tank up anymore. So you kind of set it and forget it. So it's a great option for portable setups. And you can see here I can lift it easily. So one person can handle it in the field without any problems. And the last piece to a portable setup is our portable tubing reel. So hopefully a lot of you are familiar with our water level meters, and you're seeing a lot of similarities here. So we've got our nice convenient carry handle, sturdy frame. So when I set that on the ground, the tubing staying up off the ground. So I'm not picking up any debris that I don't want to introduce into the well. We have our handle here.  So really easy to lower the pump and raise it. We have our quick connect fittings on the front. So we have our quick connect for a drive line here. So from the control unit, that snaps into place easily with no tools. And on the other end, we have our sample line connection here.  And the sample would come up through the tubing out here to your sample body. Now in terms of tubing, what we usually do with a portable reel is we have our dual bonded. So it's dual strip tubing and it's bonded together. So that makes it easy to coil it on and it keeps all the tubing story organized. I have a sort section here. So it looks like one, but it actually is two pieces of tubing. So you have one for drive line, one for your sample line. That's all connected through the hub. And again, comes out to these quick connect fittings. So lots of different options available in tubing, but with the portable reel, typically we would go with the quarter inch, quarter inch dual strip bonded. So the reel itself we offer in three different sizes. So depending on the deployment depth that you're sampling at, we've got different size reels to accommodate that tubing. And on the faceplate and backplate steel, so very robust keeps everything protected. So all of those pieces together, one person can easily handle all of that to bring everything out into the field. And then obviously the sample bottle, depending on the type of sampling you're doing, there will be different sizes, different types to use. Now on the other side, looking at a dedicated setup, all of the pieces would be the same except for how you actually connect at the surface. So you would have instead of the portable reel, we'd be using our dedicated well cap. So again, maybe some of you out there are familiar with their two inch locking well cap. From the outside it looks the same, but on the inside we have some differences. So our insert here, again we have our quick connect. So we can connect our drive line quickly. On the other end, see it with the light here, we have push fits for tubing which would be running down to the dedicated pump. So that pump would stay in the well all the time the tubing would stay and it would be connected to both sides of our push fits here. And on the other end, I mentioned the quick connect and we have a push fit for our sample line. So we'd come, have our sample line go into the sample bottle, put everything together, start sampling. When we leave, this would stay at the well as well as all the tubing running down hole to the pump. So everything from the well cap down would stay and everything else you would take with you from location to location. Now we also have on the bottom our eyeball. So that serves a couple purposes. One, we have a safety line when we have a pump down well, we can tie off a safety line. So we know that that intake depth is the same all the time, plus it supports the weight of the pump. And let's say you want to also deploy some of our level loggers or you have some other transducers that you want to deploy, you can use that as a hanging point. So maybe you have some Kevlar cord or something like that, you can hang other pieces of equipment from that eyeball. On the top here, we have an access hole. So that pops out and see here, you've got an opening. So you're able to access the well without disrupting the pump down hole. So you take the cover out and you can take static water level readings. So any of our water level meters, the probes will fit through there. So you're able to take that static reading without disrupting the pump or the intake depth down hole. So all in all, it's a great piece when you have a dedicated setup. As I mentioned, that's the only difference. Everything else would be the same. So you still have your sampler, control unit, air source, and your sample bottles. Okay, so now you see all of the options we have available in terms of ladder pumps, double valve pumps, deployment options. That's great. But how do we actually now take all that knowledge and apply it to the applications that we come across daily or quarterly, whatever intervals you have. So like I mentioned at the beginning, I put together a few case studies. So I want to go through the background information on each. And from that, give a recommendation of the type of pump that I would use and also explain why I came to that conclusion. So case study one, what do I know? So I've been asked to do VOC sampling. I have six wells to sample yearly. My well is two inch in diameter. I have a depth, the pump of 50 feet and a static level of 40 feet. So all of that together, I calculate that out and I would say a 407 blotter pump portable setup. Now how did I actually come to that conclusion? Well, the first one is VOC. So I know I need to have low flow, nice steady flow. And with VOC, I want to ensure that the drive gas hasn't come into contact with the samples. So I want to have defensible data when I submit that for analysis. So that puts me into the blotter pump because I mentioned the drive gas only stays on the outside of the blotter and never comes into contact with the sample. So that right there puts me into blotter pump. Now a two inch well, I don't have any restrictions in terms of diameter. So I can use either the 1.66 or the one inch. For this, I probably would use the one inch just because it is a portable setup. So I have lighter weight. So when I'm lowering that and raising it, I'm using a lighter weight pump. Again, you can still use the 1.66 to have that increased volume if you want. But I'm looking at low flow. So I don't need to have that increased volume to have a higher flow rate at the surface. So the one inches is a great option. Another reason why I'm thinking blotter pump is I know at my depth, the pump is 50 feet. My static is 40. I have 10 feet of head. So I don't have a lot of water above the pump itself. So a blotter pump is a little more suited for a shallower head above the pump. So that's another reason why I'm looking at a blotter pump. Now case study two. Again, what do I know about the well? So I've just been asked to do standard sampling. So just general water chemistry. So higher flow rates are possible. So no limitations there. Three wells to sample every year. This time I have a one inch well. So a narrower diameter well depth the pump of 30 feet and a static of 15. So all of that together puts me into the 408 double valve pump and I'll be looking at a portable setup. Now why did I come to that conclusion? The biggest thing here is the diameter of the well. So I have a one inch well. And I know with the pump options I have available, I can use my double valve pump five eighths inch diameter. Now I didn't mention it earlier, but we do have a double valve micro pump. So a 408m and that has a three eighths inch diameter. So it's a specialty pump that that we usually use with our CMT wells. But in this particular case with the one inch well, that would be a suitable option as well. Also with the double valve pump, you can get higher flow rates at depth. So with the standard sampling, I can I can do higher flow rates. So the double valve pump works out great for there and portable because I only have to go out and sample yearly. I don't really have the need or I'm not really justifying spending the extra money dedicating pumps when I'm only going out once a year. Whereas with the portable setup, I can go with just one setup and sample the three wells, de-con between sites and I get exactly what I need to do. Case study three, a little bit different story here. So the same I'm looking at general water chemistry. So higher flow rates are possible. Five wells to sample quarterly. So it's a higher frequency of site visits. I have a four inch well and I've got a much deeper deployment. So I've got a depth, the pump of 650 feet and static is 300 feet. So all of that together makes me point to a double valve pump. And I'd be looking at a dedicated setup in this particular case study. Now why am I I come into that or why did I come to that conclusion? First thing is the depth. So I'm looking at 650 feet. So again, I mentioned a double valve pump. You can obtain higher flow rates at greater depths. And in this particular case, I've been asked to do three well volumes or I'm doing three well volumes. So I want to get as much of the sample to the surface as quickly as possible that for a way I can do that. I've got a four inch well. So I can use the 1.66. I've got a larger diameter body. So I've got increased volume within the pump. So I can get more of that sample up. And I'm looking at a dedicated setup because I have to go out and do quarterly sampling. So one, I'm doing a lot of site visits. So you'd be spending a lot of time bringing the pieces out, packing it up, bringing it back. So it would be easy just to bring my gas source and my control unit connect. I'm good to go. And the second part is why I want to use a portable setup just with the overall depth. So 650 feet, that's a lot of tubing. And it takes a lot of time to lower and raise the pump up. Plus then I would need to decon 650 feet of tubing between each of the five wells. So this one works out great for a dedicated setup. I lower the pump down. I've dedicated tubing. So I'm not spending the time each time I go out quarterly to lower, raise, decon. So perfect application for a dedicated setup. Now I mentioned earlier in the presentation that the portable reel, we would usually use the quarter inch by quarter inch bonded tubing. In this particular case, I'd be looking at single line tubing. And I would be looking at three eighths inch for the drive line and quarter inch for the sample line. Now, why do I want to have a larger diameter drive line? If you think back to when I was talking about the differences between the two pumps with the double valve pump, when I lower that down into the well, water fills up through the pump body, but it also goes up through the drive line and the sample line to the static water level. So now I have in the drive line, which is then getting pushed down when I drive the gas from the surface down into the pump body, I'm pushing a larger volume of sample down and then up through to the surface. So that's how you can get a higher flow rate as well. By all means, I could use the quarter inch quarter inch. But if you can envision 650 feet of tubing with 350 feet actually having water in it, the difference in volume between a quarter inch and three eighths of an inch, that's substantial. So it's just going to give me an overall quicker result up at the surface so I can move on to the next well quicker between sampling events. Okay. So I hope you enjoyed that video. I think it's great to hear from the suppliers because they understand the technology very well. In terms of sort of the take home messages and perhaps some of my own personal experiences with challenges and things that can go wrong in considerations, I'm just going to cover a few of those now. So what have we learned so far? There's two key types of pneumatic pumps, okay, for low flow sampling. They are bladder and double valve pumps. Bladder pumps are really highly regarded for sampling of VOCs because the drive air doesn't come in contact with the sample. Imagine if it could, that's potential for you to lose volatiles into the air. So that's why they prefer the bladder. However, double valve pumps are excellent low flow option, particularly for sampling at depth. So they didn't really go into it in that video, but there's a true cutoff point of 150 meters where you just can't go deeper with a bladder pump and you need to switch to a different sort of pump. With a double valve pump, you can go very deep. In fact, hydrogen is sampled from wells deeper than a kilometer using double valve pumps. I'll talk a little bit more about that later. In terms of dedicated versus portable, well, there's a few considerations with that video they showed in terms of the portable setups. Very few people in Australia actually use those portable reels. The majority of people using these sorts of pumps are sampling for contaminated groundwater and therefore they're worried about the cross-contamination and deconing that tubing. So typically people buy the tubing and dispose of it. However, if you're working in research and that sort of things, well, cross-contamination is less likely and therefore those sort of portable setups are used. So keep that in mind. Dedicated pumps are fantastic and I would seriously recommend them anywhere where there is a real repeated monitoring program. What it comes down to is a calculation that you yourselves need to do for your clients, which is well, how long does it take for me to deploy and remove my pump each time? What's the cost of consumables and what does that add up to in terms of cost effectiveness versus using a portable versus dedicated? The other thing you need to consider is the quality of the samples you're getting. There's no doubt that dedicated samplers achieve a much higher quality of sample. Why? Because they don't disturb the water column. So you can get stabilization of parameters quicker and you have less chance of changes to the water quality in the water column also well. As I mentioned, there's always economic considerations. You know, the sorts of sites where double valve pumps are typically deployed are things like landfills and facilities where you have an ongoing monitoring requirement. Now, some of my landings and then we'll get to Q&A. If you have any more questions, feel free to log them. My experience over time that I just wanted to share, I suppose, is things to really be careful of is choosing between compressors and bottled gas. You need to calculate how much air your pump is likely to use and we can help you with this. But you need to choose carefully between compressors and bottled gas because compressors can get to a point where they're needing to run all the time to drive the pumps and they will overheat. So we have some rules of thumb we use depending on the deployment depth that you're doing and the tubing diameters for whether or not to use bottled gas or compressors. But keep that one in mind. When deploying dedicated samplers, often you can have a lot of tubing, right? So particularly if you're sampling down at the sort of depths they referred to before. So there it's good to have your tubing set up on a sort of tubing reel that you can lower down into the well as you're deploying rather than trying to unravel it off those cardboard rails that you get. That way you keep things very ordered. Jewel bonded tubing is quite good. However, when you get to depths of over about 300 meters, buoyancy starts to become an issue with these pumps and you need to use HDPE tubing as well putting weights on the bottom of the pumps. So use HDPE tubing because it's stiffer and doesn't expand as much for each pumping cycle and you use weights to overcome the buoyancy considerations. So on some of the projects we've worked on, we've actually had solid stainless steel below the pumps. It's almost a metre long and a diameter of about 40 millimeters. So really quite heavy weights to get those pumps down where we need them. With the double valve pump, a common rookie error is to be in a real hurry and to set your drive period for too long. You've heard from the presenter, Joe, that it's a good day. You can have all that water in the line and you can effectively drive through the pump to accelerate pumping. The thing to be careful of is if you drive all the water out of the pump, then you're blowing a whole lot of air back through your sample. So you need to be careful in selecting your drive and vent cycles to ensure that the air never enters the pump chamber but always stays up above it in the drive line. Now, that's about it from me. I hope you've enjoyed it. I have one question in the Q&A, which I will have a look at now. Hi, Richard. It's from an anonymous attendee. Do you have a rule of thumb to preemptively assess flow flow sampling is going to draw down the standing water level too much to be viable? Therefore, some rough values for hydraulic conductivity, installation, air lift, yield, etc. I know the minimum flow rate will affect this. So maybe a standard sized bladder. I don't have a guide as such for you. Typically, people monitor the drawdown when they're in the field. One thing is for sure is once you've worked it out the first time in your sampling round, it's obviously something very good to record for your next sampling round. So you already know. So that's one thing that I often find people don't record that they should. And we use field tablets to record these things is just what were your pump rate settings? What was your flow rate that you had? And if you're measuring drawdown, then you effectively know those numbers. That's one way to do it. That's the last and first question of this webinar. I was hoping for more questions. There is another one. Do you, Richard, do you measure the standing water level to ensure there is no drawdown from the pump to ensure the sample is representative? Do you run hydro cam measurements in intervals over a certain time or purge a certain volume from the well to ensure the sample is representative? So there's a few things in that. There's really three questions. Yes, we run hydro cam measurements. We typically use handheld water quality meters with data logging functions. And they can be set up and configured to give you a sound signal when you have a tooth stabilisation. It's really important to have those. In fact, you need them to comply with that publication 669 that I mentioned. So that's what they're referring to as stabilisation parameters. So with the standing water level questions, so do you measure the standing water level? People do that in a couple of ways. If it's a long term sort of sampling event, you might actually choose to use a data logger. But people often use drawdown meters to keep an eye on the drawdown level that's occurring. Other people use manual dippers, all of which we have here for rent and sale. Now the last part is probably a bit of a loaded question, really, or purge a certain volume from the well to ensure the sample is representative. So there's two sorts of sampling in terms of purging. Really, there's low flow where we've got those assumptions I mentioned at the start. So low flow is assuming that we're getting water in from the aquifer. And therefore it's not about how much you pump. It's about the stabilisation of the parameters. So really important to understand that. So it's not about the volume. It's about showing that you've got repeated readings showing that the water coming into the pump is stable within certain bounds. And those bounds are actually listed in some of the guidance documents. So low flow, it's not about the volume. If you don't think low flow is going to work, right, or if the specification for the monitoring round is to undertake purging, purging typically is considered adequate if you remove three well volumes. Now, what's a well volume? If I think I can go back up in my presentation a few slides. Well volume is the volume of water between our standing water level and the base of our well screen there as depicted there. So if you multiply the cross-sectional area of the well by the depth of saturation within that well, that gives you your volume of water. So traditional purge as they call it involves, you would calculate that volume and you would track how much you've removed and you would need to remove three of those. This becomes a problem, right, guys, if you're dealing with deep wells, right, and so often you'll get a spec where not often but quite frequently in mine sites in particular you'll get a spec which talks about undertake traditional purge, remove three well volumes, but you end up with a lot of water, right, and that means a lot of pumping time and that means a lot of water to dispose of. Next question from Cheng Wang, I hope I've got that pronunciation correct. For the portable setup, does the tubing reel use LDPE tubing or HDPE tubing? So for the one in the video that is LDPE tubing, sometimes they'll provide Teflon coated tubing, very expensive, but Teflon is superior in terms of contaminants that will adhere to it. In other words, it's better in terms of de-conning between wells. But as I mentioned earlier, most people who are doing Contam land sampling dispose of tubing between samples, and that's one of the reasons to look at dedicating because, well, it's less waste, right. HDPE tubing is used where you're looking at high pressure applications, okay. So HDPE tubing is a bit stiffer and it certainly doesn't stretch as much as LDPE tubing. So it's actually a really good material to use for deep wells. Cheng asks, how deep can it reach? So a couple of considerations in that question.  So the standing water level is just another definition for that water that's represented in our well. What we need to be thinking about when we're setting up our pumps is what's that depth from the top of our casing where we're collecting our sample, okay. So if that depth is less than 150 metres, we can then theoretically deploy a double valve pump, an unlimited distance. And Hydrotera has really put this to the test, you know. I think the deepest is 1.2 kilometres that we have put that down. Just keep in mind when you get that deep, it takes a long time to collect a couple of representative samples. So we were looking at one or two a day at that sort of depth. So in a way, it is unlimited. We've tested it to 1.2 kilometres, which I think covers most people's requirements, you know. So that was for looking at Coal Seam gas applications. That's why that was so deep. So I hope that answers your question. Question from Ross Bonn. Do you find that saving a tubing of a pump such as a so-on is a better and more viable endeavour than decontaminating tubing between pumps with a setup such as a Bennett pump? I've only had limited experience with the Bennett pumps. Just to read your question again to see if I can answer it. Do you find disposing tubing with a pump such as a so-on is a better and more viable endeavour than decontaminating tubing between pumps? With the Bennett pumps, its strengths are that it's sort of got a mechanical piston within it that drives the water to the surface. So you can achieve quite high flow rates at depth. The Bennett pump though is expensive and deconing the equipment is labour intensive. So the vast majority of people don't use Bennett pumps. I've seen them used in some applications but the vast majority of people tend to go for the so-on and QED bladder pumps and double valve pumps. In our rental fleet we have QED for our portable bladder pumps because they have a very easy bladder to change and we have so-on for all our dedicated sites because they have a really good configuration for the deployments. So you would have seen in those pictures that the bladder gets pushed from the side, squeezed together, that has less propensity to get blown off the end than the QED setup. So QED for our rental fleet because it's easier to change the bladders and so-ons for dedicated because a better design for those applications. In terms of disposing of tubing, I mean disposal of tubing is something that annoys me as an environmentalist but it's more time efficient than trying to decon the Bennett pump. So what's the industry need to do? It needs to look at the cost effectiveness of dedicating those sort of pumps we just looked at because they are a superior lower cost pump to use in these applications and something like a Bennett pump which is really quite big to take around between sites. So that was a long-winded answer to that question Ross but I hope that helps. I think we've finished up on questions. I've got maybe a couple in the chat here. What is the criteria for stabilisation parameters? That's listed in those guidance documents that I referred to on the slide. So have a look at those. They've got some indicators and their error bands that you can have around those to define stabilisation. Thanks Ross for that nice comment as well and Adam. So I think we might leave it there. We have four minutes over time. I really appreciate you all coming along today and keep hydrogen in mind if you need some advice on your monitoring needs. It's been great to have you here today. It would be good to get some feedback on the format of this one. This is the first one where we've combined the video side of things to get the supplier's knowledge in with I guess more of the application knowledge that HydroTera brings to the equation. Thanks very much for joining us today.


Thanks, everyone. As the partner said, I'm Paul Gansel. I'm a software developer in the New York office in Bloomberg. And I also maintain Python Datetail. So just a warning for this talk. I am dialectically challenged. And so it's really not going to be possible for me to mentally transform these Zs to Zeds. And I'm going to say it a lot. So you should just be prepared every time I say Z. Just think Zed. OK, so I'm just going to get right into it. Because as everyone knows, time zones, when you want to learn about them, they should probably take a half an hour, 40 minutes at most to learn. But I only have 20 minutes, so I'm going to go fast. So for starters, we have UTC. Just to get everyone on the same page, UTC is sort of the reference time zone. No one lives in UTC. No one really does anything in UTC. But it's supposed to be an easy time zone that you can transform your local times into. It's supposed to be monotonic, but it's really monotonic-ish.  Don't ask me why. Another concept that you should know about is time zones versus offsets. So right now, the offset from UTC in London is one hour, UTC plus one. That's an offset. Whether that's in London now or in France in six months makes no difference. That's always, if you see UTC plus one, just add or subtract, I always forget, one. And that gets you to UTC. Europe slash London is a time zone. It's a set of rules for transforming your local time into UTC. Now, what's BST? So if you print your current daytime, you get BST. Is that a time zone as an offset? It's kind of an offset in the sense that it only refers to the part of your London time that is one hour ahead of UTC. But the problem with these is that these are very highly context dependent. Because if you're here and you say BST, that means British summertime. If you're in Bangladesh, it means UTC plus six. And if you're in Papua New Guinea, it's Bougainville Standard Time, which is UTC plus 11. So as a general rule, people will like to see these if you display them. But don't count on them to mean anything. And don't try and parse them. So now here's everyone's favorite part, where I go through all the crazy edge cases. And honestly, there's not actually time to go through all the crazy edge cases. So I'm going to start us off easy with Australia. They have a non-integer number of hours offset in certain parts. Like, oh, that's real spooky. Then we move on to Nepal. They have not even an integer number of half hours. They're off on a 15 minute. And if you go into history in Liberia before 1979, they don't even have an integer number of minutes. It's off by 30 seconds. So you can say, OK, well, at least we know that daylight saving time, the only reason you're going to change is daylight saving time, right? Wrong. The base offset can also change. So in Portugal, in 1992, the Portuguese decided instead of being in Western European time, they wanted to be in Central European time. So they wanted to move over by one hour. And sensibly, they did this when they were already transitioning from summertime back to standard time. So what they did was they said, OK, in September of 1992, we're going to stop being on Western European summertime, and we're just going to start being on central time, which means that the UTC offset did not change, but the DST offset did change. So that can happen. And you can note that this first change didn't go so well. They were having sunsets that were after midnight. So about four years later, they did the same thing in reverse, with another offset change, DST change with no offset change. So OK, maybe you say, all right, well, yeah, there's that one weird edge case. But maybe at least if you're on daylight saving time, you're only going to transition once per year, right? Incorrect. In Morocco, since 2012, what happens is they go onto daylight saving time, like many people do, in the spring. So you have your standard transition there. And then at the end of July, they go back to standard time for about one month. And then they go back onto daylight saving time. So what's going on here? Well, Morocco has a large Muslim population. And Ramadan falls in the middle of summer. And in Ramadan, Muslims aren't allowed to eat until sunset. And so their solution to this is to say, OK, we'll just have sunset an hour earlier during Ramadan. So you have to keep that in mind. You can say, OK, well, all right, we have that. But everyone at least does daylight saving time at 2 in the morning or 1 in the morning. So I'm never going to see an ambiguous date time that is in the middle of the day, right? Incorrect. In Kiribati, or Christmas Island, in 1994, the Kiribatians, they decided that they preferred one trading partner, the other Australia, or the US. I forget which. I'm terrible at details. But essentially what they said was they live right on the international date line. So they said, all right, we're just going to switch from being on one side of the date line to the other. So we're just going to skip December 31. It's just like December 30, 1159. And then one minute later, happy New Year. So you say, OK, maybe. Yeah, that happened. It was the 90s. We were watching a lot of Seinfeld, water cooler talk. But no, it can happen today. It happened, again, in Samoa in 2011. And if you go back pretty far in time, you can see in the Quadrillion Atoll, they went the other way. So in 1969, there were two September 30 in the Quadrillion Atoll. So OK, now you say, all right, fine. Yeah, the offsets are all crazy. The people will do crazy stuff with their offsets. But at least we know that if we're in one place, there will always be one time zone. I can always say what the time is in a certain time. China, in an effort to rationalize their time zones, said we're going to have one time zone throughout all of China. It's going to be UTC plus 8. So over here in Beijing, that's pretty good. If you're over here in Xinjiang, that's not so great, because the sun rises at 4 in the morning. So in Xinjiang, a lot of people start using what's called Xinjiang time, which is UTC plus 6. But the Chinese government doesn't recognize Xinjiang time and doesn't really care for it. So all the trains still run on UTC plus 8, and all the planes do, and all the official offices. And if you look on Wikipedia, it seems that the breakdown between whether you use Xinjiang time or Beijing time is your race. If you're part of the Uyghur minority, you use Xinjiang time. So this is a racial time zone. Get that through GDPR. All right, so now I thoroughly scared you. Time zones are terrifying. They're crazy. Why should we work with them at all? Why can't we just go UTC for everything? Well, you can imagine that it would be a common occurrence in, say, Bloomberg to say, I would like to know when trading ended in New York on any given day. So I can write this nice recurrence rule that says Friday, 5 o'clock, trading ends. I could maybe say Friday, 10 o'clock UTC, but is that really going to work when I change my UTC offset because of daylight saving time? It's not, right? So I still have to say, there are still times where there's something important in looking at the civil time. The civil time is 5 o'clock. That's what people actually use. And when you want to find out when that time actually is, you need to make the mapping there. So how does Python deal with this? So Python has a very specific time zone model. And the way it works is there's an abstract-based class called tzinfo. This is one of these z's. And you're supposed to subclass it. And your subclass should implement three functions, tzname, UTC offset, and dst. And these are functions of the naive daytime. So it's supposed to be one sort of singleton object that represents the set of rules. And those rules are implemented as functions. So here's an example. This is Eastern Time. I've implemented it. I have this little isdaylight function that uses actual US rules. And if I go on one side of the daylight saving time transition and then on the other, I get the appropriate thing, right? So then, if I go through this appropriate rules type situation, I say, all right, now I go from UTC. I get the first one, the Eastern Standard Time. And then I go one hour ahead in UTC. And now it shows up, instead of as 130 minus 5, it shows up as 230 minus 5. So what's up with that? So to explain why that's broken, you have to understand ambiguous times. So ambiguous times are times where the wall time occurs twice. As you remember, the functions that you're implementing are functions of the wall time. So obviously, if you have two wall times that are differentiated only by their offset, there's no function that you can write that will map wall times to the correct offset. So here's an example. You have two 130s, one on one side and one on the other. So how does this work in Python? Up until maybe a year or two ago, it just didn't. It was just broken. It was like, you just can't do that. But Python 3.6 introduced the fold attribute with PEP 4.95. And the fold is a property of the date time that tells you which side of any given fold that you're on. So here, I have this implementation that says 130, and then I pass it fold. And if I put fold equals 0, it's on the daylight time because that's the first one that occurred. And if I pass it fold equals 1, that's the second time that time occurred. And so I can write a function that takes this fold and turns it into an offset. So now I'm going to take a brief digression into the semantics of comparison. So if you have two day times and you want to know, are they the same daytime? What does that mean? In Python, what it means is that if they're in the same zone, and this is a bit complicated, but if they're in the same zone, what it does is it imagines that they're not in any zone at all. It just takes the naive portions and compares them, which is a fine rule when you don't have ambiguous day times because that always means the same thing. When you do have ambiguous day times, you have to decide whether the fold is part of the thing you're comparing or not. And I don't know why this decision was made, but it was decided that that is not part of what you're comparing. So if you have two things, you have your 130 minus 4 and 130 minus 5, those are considered equal because the naive portion of the daytime is the same. Now, if you have different zones, those are still considered comparable. And what happens is they just convert them both to UTC and compare that. So you can have a situation like this, where it's almost exactly an identical situation where the naive portion is the same and the offset is different. But the difference is that one of them is in New York and the other one is in Chicago. Whereas in the previous example, they were both in New York. So in Chicago, because they're in different zones, they get converted with the offset. And then the other problem here is that I guess there's some kind of weird thing with hash invariance. I really can't explain this. I don't know why I mentioned it in the slides. But if either daytime is ambiguous, Python just throws up its hands. It's like, no, I don't know. They're not the same, whatever. Maybe who cares? Really, come on. You're trying to pull a fast one on me? Give me an ambiguous daytime? No way, buddy. So here's a curious case. This came into the issue tracker. So I have this x equals daytime. It's March 25th at 1 AM in London. I convert it to a UTC offset. I'm now UTC an epoch time. So I convert it to a timestamp. And then I convert it back. And I put it in the same time zone, same exact time zone object. And then I create another one where I just get a new instance of the same time zone, still Europe-London. So now I'm going to compare these. They should all be true, because they all represent the same time. So x equals y false, not off to a great start. x equals z true, maybe a little better, but that's still a little puzzling. But I guess that means y equals z is false, right? Oh, no, wait, it's true. So what's happening here? Why is there this non-transitive comparison property of time zones? So this comes down to what's known as imaginary times. So we already talked about ambiguous times. Now there can be a gap on the other side when you go from standard to daylight. And so I have an example here of where you jump from 1 to 3 AM. So now let's look at the values from our original example. So we have this 1 AM. It's 1 AM plus 1. But if you try and turn that into UTC, if you go to that same time at UTC, it's midnight. And then one second later, or one hour later, it's 2 AM. So that 1 AM didn't actually exist. You can just construct a non-existent time. But why was it non-transitive? So we can assume that it's some sort of undefined behavior otherwise, but why was it not transitive? So if you look here, you see that when you take the London date, you turn it to UCC, you get this midnight date. And when you turn it back, you also get midnight at a different offset, but it's in Europe. Now when you look at y and z, y and z are both the existing time, the UTC time. So you maybe know where this is going. If you look at x.tzinfo and y.tzinfo, they're the same object. So what's the rule for the same object? You compare the naive portion. So the x has 1 AM, y has midnight, and so they're not the same. But when you go x versus z, they're actually different objects. And that's what Python uses to determine whether two day times are in the same time zone is the is relationship. And so what happens there is they go, oh, these are not the same time zone. Let's convert them to UTC. And x can go to UTC just fine. It's just UTC that can't go to x. And so they both go to UTC, they get the same daytime, and they're the same. So that's your non-transitive daytime. So how do you work with actual time zone objects? I don't think I'm going to have time to go into the details of how to use date utils, particular time zones, but I'll tell you right now I recommend that you use date util over PyTZ. PyTZ was doing the right thing for like 14 years before date util was even able to do the right thing. But now date util is able to do the right thing, and it's a little more pythonic. So if you take, date util provides a number of time zone objects. I'm going to take this one that represents specific time. I can just pass it to the constructor as you would expect from the documentation. So you set tz info equals this thing, and it works just fine. Now if I want to take that and just keep the wall time, but say this is actually a wall time that's not in Pacific time, it's in Eastern time, I can use the dot replace. And that just sort of drops off the tz info and gives me a new date time with Eastern time in it. But if you want to know the same moment in time represented in Eastern time, so I want to say you're scheduling a call, and it's represented in Pacific time, you use as time zone. And what as time zone does is it goes to UTC, and then it goes to whatever other time zone you told it to go to. So that's how it works with date util zones. Now with pi tz, if you attach a pi tz zone, if you take a date time and you do as time zone for a pi tz zone, it'll work just fine. It's exactly what you expect. But if you construct a date time directly that way, or use replace as I mentioned, it fails in this horrible way. You see this should say Eastern standard time or Eastern daylight time or something, but it says LMT. The offset is minus 4.93 hours. What is that? Well, that's local mean time. That's what it was before time zones were standardized, and that's what it was like in New York. And pi tz has a strange time zone model. All of pi tz tz infos that get attached to date times are static offsets. So what happens is pi tz will just take the date time, figure out what offset to attach, and then attach it directly to the date time. This has some advantages, such as being able to disambiguate between ambiguous times and imaginary times as you're attaching the date time. So what they do is they take the time zone object, then they localize to the date time, and that attaches the right one. But if you do some arithmetic on it, like you add six months, there's no hooks for it to update that information. And so what happens is it just still keeps returning the daylight time. So you have to use the time zone object again, and you do normalize, which is essentially saying, figure out why this is wrong and do the right thing. I have way more detail on this in my blog posts on blog.cancel.io. It's called pi tz, the fastest foot gun in the West. So how do you handle ambiguous times? So if you're using the as time zone, where you have something that's already UTC and you want it as an aware date time, that'll just work with both day util and pi tz. Pi tz will set the fold attribute. Pi tz will not, because pi tz doesn't need the fold attribute and doesn't do anything with it. If you're working in something before 3.6, and who really is doing that these days, then day util provides a backwards compatibility mode that you can use the tz.infold method.  The default is just setting it to one. It'll set the fold method if you're in 3.6 plus, or if it's not, if you're in 2.7, it'll create this sort of daytime subclass that has the fold attribute back ported. So this has most of the same semantics, and you can use it as appropriate. And also, as time zone, we'll still work that way. If you wanna detect ambiguous times, day util has to detect ambiguous, and so, or it's just called daytime ambiguous. So you pass it a daytime, it tells you whether or not it's ambiguous. If you want, so if you wanna say something, you have it coming in, say you're adding an hour each time, and if it's an ambiguous daytime, you wanna be on one side or the other, you wanna be on the standard side, you can sort of say, if it's ambiguous, set fold to one. But you actually don't have to do this because the spec says that if fold is one on a non-ambiguous time or a non-gap time, then what you get is just whatever the value is. It has no effect. So you can just set fold equals one all the time, and it'll get you standard. But if you want it to be neat and not see folds, then don't set fold equals one. So handling imaginary times, day util provides a daytime exists. It's the same as a daytime ambiguous. You ask if a daytime exists. If it exists, it'll say true, if not false. Generally, the kind of hard thing to do is if you're sort of adding one hour at a time to an aware daytime, and you're at 130, you go one hour ahead, it should be 330 instead of 230, then the thing that you usually wanna do is not skip back, you wanna skip forward by an hour. So day util added during one of the sprints by this young lady right here in the second row has this resolve imaginary function. You pass it something, and if it's not imaginary, it just gives you the same thing back. If it is imaginary, it skips forward by whatever the gap was. So if that gap is one hour, it skips forward one hour, and in the case of Christmas Island, if it's one day, you skip forward one day. And both these functions will actually work just fine with pi tz time zones. All right, so I'm gonna skip over this part because I wanna be able to take questions. Just a parting response. A lot of people ask me things about what should I do with time zones and things like that, and I'm happy afterwards to take all kinds of questions. I could talk about this stuff for hours. The things that I would keep in mind are civil times versus timestamps.  If you have something where it matters what the time on the wall is, such as a meeting, almost every date that you care about in the future, other than the asteroid will hit on Monday at 2 a.m. UTC. If it's human related, store it as actually a local time with the time zone. Don't convert it to UTC because that mapping is not stable. You could, as was in the case of Egypt all the time when they decide whether or not to have daylight saving time or whether to have daylight saving time during Ramadan or not, they will give you three days notice. Your phone is not necessarily gonna be updated there. You could have scheduled the meeting three days ahead of time, even if you managed to update your phone correctly. If you stored it in UTC, it's now off by an hour. So for things in the past, you can store them as UTC just fine. As long as you care about the time between two events or how long ago it happened, like the exact time that it happened, you can store it in UTC or UTC with an offset. And with the INA, never rely on these three letter abbreviations. You can use the INA keys, but if you're localizing, like if you wanna show someone something that's some time in Ukraine, you probably wanna use CLDR because those keys are not intended to really be human readable. All right, so that's it. You can try and help with DayUtil. I'm open for a lot of pull requests. We've been running sprints here and they've been going fantastically well. Check out my website or my blog. And thanks to Bloomberg for flying me out here and hosting this conference and everything. All right. So I think we have two minutes for questions. I just wanna thank you, Paul. That was quite interesting, especially because I'm sure we all have one or two nightmare stories about working with time zones. Anyone? Yeah. Thanks for talking. What have been some of the practical ways you've faced or overcome some of these challenges in your work here? Well, so to be honest, I hit most of these problems when people come to the issue tracker of DayUtil, which is why I'm always old hat by the time I have to do something. If I ever have to use this stuff myself, it's like I know where the pitfalls are because I had to fix 10 other people's bugs. A lot of times it comes down to just making assumptions it comes down to making assumptions about what the time zones are doing, not really understanding the model. And after every time I give this talk or any related talk, a lightning talk or anything, what happens is someone comes after me afterwards and says, oh, I have some bugs in prod because I've been using PyTZ by just attaching it to the TZ info. So watch out for that. Like do a search, a control F over your whole code base for PyTZ time zones and check to see that they're not being used that way. Okay, I think that's all we have for time. You can just find Paul afterwards if you have any more questions. We have a five minute break and then we'll start the next session.


Former President Donald Trump referred to people who have been imprisoned for the January 6, 2021, attack on the US Capitol as hostages during a campaign rally on Thursday, his latest move to embrace his supporters involved in the riot.Ateeth the beginning of the rally in Houston, Trump stood saluting as a song in which Trump collaborated with men known as the J6 Prison Choir who were incarcerated for their role in the attack was played to his supporters in attendance, the riot wasn't. Attempt to overturn Trump's election loss to Democratic President Joe Biden, which the frontrunner for the 2024 Republican nomination continues to falsely claim was the result of widespread fraud. The Biden gets his way. The United States will be reduced to an impoverished third world crippled blackouts. We're going to have crippling blackouts. We're going to have people literally begging our enemies for mercy. We're losing all of our power with what they're doing. It's crazy. It's crazy. So Biden's crooked Joe's green new energy calamity is one of the biggest factors causing, as you know, the inflation disaster, which is about the worst we've ever had. So we're going to create millions of new jobs and we're setting the ambitious goal of achieving the absolute lowest cost for energy and electricity. We're going to rebuild our grid system. We're going to do things that nobody's ever thought possible, and we're going to do them fast. It's going to get done very fast. And this place and this state, but this particular place, but this state will be one of the big beneficiaries. I can tell you that you have a lot of states will benefit, but this will be one of the better. We've seen under the Biden administration, energy security is really it's national security. Think of it. Energy security is national security. That's what it is. And we don't have national security now.  If you don't have energy and if you don't have borders and if you don't have fair elections, you don't have a country. You don't have a country. And we're close. We're close to having no country.


Hi everyone, Joe for Jasper's case breaks calm coming at you with 2019 2020 upper-deck stature hockey three box random team break number three One spot gets you two teams and there is a combo because there's 31 teams Big thanks to these folks right here. So let's double this up really quick one spot gets you two and There's the combo right here sabers and caps Let's roll it. Let's randomize it three times for this three box break one Two and three after three times we got Kevin down to couple Scots Three times for the teams one two and three That stars down to sharks All right, Kevin with the stars chatted with the combo Scott with the Canadians in the Doug Zach with the coyotes in the devil Scott with the Bruins Kevin with the Blue Jacks Khalil with the Oilers Zach with the Flyers came with the Prez Scott your double-ass spot mojos right here Panthers and Blues Johnny with the flames penguins for Kevin Scott with the Islanders Kevin with the Canucks Chad with the Maple Leafs Kevin with the Lightning King with the Rangers Khalil with the Black Hawks Kevin with the Wild Scott with the abs Johnny with the Jets Rory with the Senators Scott with the Red Wings Rory with the Kings Zachary with the Knights Scott with the Carolina Hurricanes and the San Jose sharky sharks All right, let's sort by column B by team Any trades? Maybe we'll give it a few seconds. Here are the the stature box right there remember I think we we mark them so we know that they're from the same Same case So this is a one-pack egg Don't remember doing any Stature Kevin's looking for Rangers Kings or Oilers if anybody's interested in in a trade those are the teams that he has right there Blue Jack at stars wild penguins lightning and Canucks And he's looking for Rangers Kings Oilers anybody's These people are here. Maybe they might not even be here What's hockey season restarting? Basketball's got a restart date right December 22nd anyone know If they've been talking about a start date for hockey. All right, maybe not Kevin. Sorry TWC trade window closed. Let's print and rip Kevin says not sure for hockey Ryan a a soft is saying that possibly Aiming for January 1st. All right, it's not too long after basketball then are they gonna do a full season I know basketball cut a few Like ten games or so is hockey trying to do all games I don't know where the hits are, but these last two hits The second one the hit what's in here? I Don't know. We'll just do these one at a time. Here we go. There's a Vechkin Pretty good-looking cards right here coat Kanemi For the Canadians. Oh Vechkin goes to the caps Grab my list here so the Ovechkin goes to The combo Chad with the caps and then the Canadians will get the put Konami that would be for Scott Coran and the Canadians Got a numbered card here Giovanni Smith kind of hard to see the numbers right there But that's the 399 255 out of 399 We've got a green Carl Grunstrom To 149 118 out of 149 for the Kings that's gonna be for Rory The Red Wings gets the Smith that'll be for Detroit. That's gonna go to Scott Scott corn We got Nico Sturm 60 out of 60 out of 85 that is for the Minnesota wild that's gonna be for Kevin Doug Gilmore The 75 that is 5 out of 75 for Toronto that's gonna be for Chad And here's our autograph right here that's to 75 it's Max Jones Anaheim ducks that's gonna be for Scott Corwin to 399 Kirby doc For Chicago Khalil and we've got Century momentous Mike Madonna for the stars Lifting the cup right there So Ryan a is saying that they haven't revealed how many Games that the NHL will play Alexander to share Or Texia actually sorry, I'm thinking of Mark to share a Texia we got Ilya Mikheyev working on these hockey names Toronto that'll be for Chad someday Ray Bork for the Bruins Boston that'll go to Scott To vertebrae vinyan terra vinyan Carolina That'll be for Scott Max Jones to 399 Ducks just saw his autograph a second ago. It's got Corwin We got rookie reliance Ilya Mikheyev 89 out of 99 It's almost got like a tribute feel right tops tribute feel that'll be for Toronto that's gonna go to Chad harp There's Mike Madonna again 20 out of 25 for the Dallas Stars Kevin Benedict and the autograph is Florida Panthers goalie Sergei Bobrowski For Florida Scott Corwin last spot mojo strikes again last spot 60% of the time last spot mojo hits a hundred percent of the time There's Philip Zinia right here for Detroit, that's gonna be for Scott Corwin as well Final box. All right final box. I think that's the autograph on the very very bottom Noah Dobson Islanders That's three out of 20 for the Islanders Scott Corwin again. Nice We got Nick Suzuki Canadians Scott Patrice bourgeois Bruins Scott He's heating up. He's on fire Jonathan masher salt Golden Knights Zachary Ville Hainola to 399 Ville Ville Ville Winnipeg that's gonna be for Johnny Another one for you Johnny Winnipeg 7 out of 99 Blake Wheeler There's Jerome Eginla He's pretty good right 126 out of 149 Calgary that's gonna go to Johnny. We've got Carl Goonstrom to 45 44 out of 45 For the Kings that'll be for Rory and the autograph is Cam Neely 54 out of 65 For the Boston Bruins that goes to Scott Corwin There you go ladies gentlemen very nice break Thanks for watching. Thanks for breaking with us. We'll see you next time for more. We got series one hockey Available on the site right now jasmicecasebreak.com just dropped recently I don't think we'll be able to get to it tonight if you're watching live, but Definitely something we can do tomorrow Saturday. Thanks for watching. I'm Joe. I'll see you next time for the next break. Bye. Bye