Okay, well, this is our final lecture for dilution as an attenuation process, sometimes. Today, we're going to wrap up our talk about delusion as an emanate process. So Dave, can you give us a quick update from the last lecture? >> Sure, let's put this graphic up that we used in the last lecture. The way to visualize this is to have a vertical control plane, perpendicular to your ground water flow, and then you use the combination of the concentrations the ground water velocity and the size of the plume, you get a mass discharge, that's a grams per day number. And mass discharge in this case, you're basically using that to describe the amount of loading. >> That's right. And then the other term, mass flux, is mass per time, per area, such as grams per day, per meter squared. Now just a quick note, that many earlier publications, the mass flux was used instead of mass discharge for this grams per day number. So you just have to be careful. But now the convention is that the loading is called mass discharge, and at this in the most common units of grams per day, and this mass flux is this loading per area, based what it goes on. So you can use this mass discharge as a first-order approximation of the impact, or it could be used for prioritization. >> And maybe let's a little bit of time talking about how this prioritization works. There's a lot of variability in the mass discharge numbers from site to site, right? >> That's right. So, we'll first talk about OoMs, or Orders of Magnitude. These are these factors of 10. And I think the main message is that our business is a order of magnitude type business. And if you look on the left there, we have this plume map. And typically we draw them using orders of magnitude, like the outer contour is 1 microgram per liter. Then ten microgram per liter, 100 and 1000, they step up by factors of ten. And Dave, what's on the right hand side? >> On the bottom right, we've got basically hydraulic conductivity values. So these are a bunch of values, the source here in this case is the Biochlor manual, this modelling software, but basically describing that if we're talking about various types of geologic media, all the way from clays to gravels and you're talking hydraulic conductivities in terms of this order of magnitude changes. So you might use terms as such as like a 10 to the minus three sand or 10 to the minus six clay. In this case, we're talking about the centimeters per second hydraulic conductivities. So a lot of times, we're dealing with concentrations or hydraulic conductivity terms in these orders of magnitude type terms. >> Okay, and that sort of sparks some thinking on our part. So let's expand our discussion and think about other natural phenomenon that are based on this idea of orders of magnitude, so Dave is going to give you a test here, I'm going to show you some pictures. >> Okay. >> Can you tell me what is the natural phenomenon and what is the scale that described it? So let's go to the first one here. What do you see? >> Well, this is earthquake, this one I know, so this is what we're dealing with the Richter scale here, it goes from 1 to 9. Every time you go up a unit, you're talking about an increase in damages by a factor of 10, right? >> It's orders of magnitude. Okay, let's do this next one, next test. What is this phenomenon? And then, what's the scale? >> These are photos of hurricanes, or hurricane damage. We use the Saffir-Simpson scale, right, to describe hurricanes or cyclones? We're going from CAT 1 to CAT 5. Basically damage again is going up by an order of magnitude as you go up this category scale. I'm familiar with the pictures on the left. I believe that's hurricane Ike and the damage associated with that. I'm not so familiar with the photos on the right, Chuck. >> Well, I was personally impacted by Hurricane Ike. Actually that's a picture of my, well, old car. That was the tree hit the chimney, and it rolled down the roof, and went right into my car. So I was part of that factors of ten damage in that Category 3-type storm. But the key point is that there are these natural sort of classification systems out there, Richter scale, Saffir Simpson some hurricane scale that are based on these factors of 10, orders of magnitude. And we said, can we do this for groundwater? And so we started out by taking all the sites that we knew, and this was using data that I helped compile along with Graham Carey from the ITRC report. And we put all of our sites together, and came up with this table here, so there's I think about 40 sites, ranked from the highest site to the lowest site. And Dave, what do you see when you look at this mass discharge table? >> Let me count what I'm seeing in terms of the orders of magnitude. But I think I'm getting up to nine different orders of magnitude, based just on the sites within these charts. >> Go on from 56,000 grams per day, which is mega site, okay? And then this one over here, 0.0078 grams per day. Now that's the smallest one. What would we call that site? >> Well, that would be pissant site, correct? >> Exactly, okay. But then you see the scale here between the pissant site and the mega site, nine orders of magnitude. And so we said, hey, can we put these sites that are here, or any site, if you knew the mass discharge, into 10 different buckets. And let's see what we did here. So this is a paper written by Dr Shawl Forhad, your co-author Brian Lonnie. But we said that if you know your mass discharge, you can go into one of these buckets. And if you look right here, if you grade them 100,000 grams per day, what are your cost find is? >> Mag 10 Plume in this case. >> Okay, and then a perimeter middle one to ten grams per day is a mag 5 Plume and then this really small one if you're less than 0.001 grams per day a Mag 1 Plume. So that's this idea you can get this idea of what they were. So one other thing we asked ourselves is what was the statistical distribution of this? Let's look at our 40 sites and see where they fall in to this magnitude scale. We're looking at here. What's the X and Y axis here? >> We've got Plume Magnitude Category on your x-axis here, so how many different sites then is shown on the y-axis. So, we've got a sort of a distribution across from one to nine in this case, a count of a plume magnitude and a few sites that fall into most of those different categories. >> sort of looks like a bell curve. Maybe a little bit. >> A little bit. A little bit. >> You can sort of see this distribution in here. But, the idea is to try to come up with this universal nomenclature or this point of reference for people. When you talk about earthquakes or hurricanes. But for groundwater hydrologists working on these plumes. It's like if you and I were at a bar somewhere and I said, Dave, I just got asked to work on a Mag 7 plume. Now, what would you say? >> Well, I've been working on a Mag 8 plume myself. >> Okay, and then we're there, and then somebody we don't know standing at the end of the bar. She says, you guys are slackers, I'm working on two mag ten plumes. >> Well, sounds like a pretty good bar, some place I might want to hang out at. >> Yeah, so if you had a bar with a groundwater focus, maybe you can do some of the things. Like instead of a martini, you would have a darcitini, right? >> Would play a lot of talking heads, once in a lifetime, water flowing underground? >> And then you'd get your ice in different sizes, based on sieve size. So, man, this sounds like a pretty good bar. >> Yeah, I think we can move on from that. >> Okay, but the idea is you have this classification system, you can also get information about potential impacts. And you can think about what's going to happen if that magnitude plume impacts a water supply well, or does stream dilution. So if we look at this one here, we have mass discharge on the left and we could see what does it take to impact a domestic, well, that's pumping at about 600 liter per day. >> Um-hm. >> And it would take a Mag 2 Plume to do that. >> Um-hm. >> And then a municipal well, pumping at 400 liters per minute, that's about a hundred gallons per minute. >> In this case, it'd be a Mag 5 Plume. >> And then for the stream with a mixing zone flowing at 4 cubic meters per second >> Mag 8 Plume does it take an impact that stream. >> Okay, and so a in those examples of this different things about this different loadings >> The sounds a lot like a TMDL concept >> That's right, so lets talk about that interesting point I just have a slide about this. In the Surface Water Program called TMDL total max from daily loads and it's the amount of a pollutant that a water body or a water segment can assimilate without exceeding their water quality standards. So here are some examples where they do some of these studies. What they really do is they say, here's the safe water quality criteria that we want to have, for in this case, Copper dioxin and they figure out what loading won't exceed that level. So in the Copper River, it's fifty four hundred and fifty grams per day and then there's Dioxin in the Houston Ship Channel about 0.04 grams per day. >> All right, so a lot of difference in these two different cases. I would like to point out that I do recognize one of the people in this picture on the right. >> Well, that's actually my wife, Dr Hanadi Rifai, who runs a big TMDL program at the University of Houston in Galveston Bay. Looks like she's holding up one of those darcitinis at this bar we've been talking about, right? >> You'd be willing to drink that? >> Yeah, but she does a lot of work trying to calculate those loadings. So in some ways, we're talking about a concept that's very similar to this total maximum daily load idea that goes on in surface water. >> Okay, well, that's pretty neat stuff. I think we may want to take a little bit of a step back and address a few questions about mass flux and mass discharge in general. Sort of covering the last three lectures that we've dealt with, so what's the big advantage to using mass flux of mass discharge concepts? >> Good question. Just think about wastewater treatment plant discharges from wastewater plants. What they want to know is the loading. Simple capacity is based on these loadings, it's mass per time and not just concentration. Concentration in some ways is just one dimension, one factor that you might understand. That you might need to know about to figure out the impact the contaminant may have. >> Well, if you're worried about impacts, why don't you just measure the concentration in the well or in the surface water? >> So you're talking about that iron on some a k paper and the idea was to use this formula but they were using more as a screening system for MTV plumes. Some unit. We're saying, if this plume continues to migrate, could it cause a problem when it hit that water supply well or surface water? But if you had a plume that had already reached a water supply well, you wouldn't need to do that. The whole mass flux discharge you just measure that well. >> And then finally, I think for an MNA course that we're dealing with is it really okay to consider dilution when we're talking about MNA? >> I think it really depends on the program and the contaminant. There's some ideas that the contaminant 1,4-dioxane has some pretty high aquatic levels. It's pretty safe in surface water relatively. But these other per or polyfluorinated substances, they're not, right? They would be much lower. So you have to think of those type things. Some groundwater mediation experts have wondered why dilution's relied upon for wastewater and air discharges, but not groundwater. So it's an interesting question overall. >> Mm-hm, well maybe let's go over the key points then for this lecture. >> Okay, first, mass discharge can be used as a prioritization system for plumes, and as a trip wire to estimate if your plume is relatively strong or relatively weak. >> And then secondly, dilution can be used as an MNA process, but really only under certain circumstances.