WEBVTT 00:00:00.000 --> 00:00:07.000 Thanks. Jane, my name is Ian Bowen I'm a hydrogeologist based in Denver, which is Cpa's region. 00:00:07.000 --> 00:00:15.000 8 office, and today, I'm going to be talking about groundwater surface wide and interactions and a little bit different perspective. 00:00:15.000 --> 00:00:19.000 I don't wanna join the audio. Right? Jean. Okay. 00:00:19.000 --> 00:00:23.000 I'm gonna guess now, , so in Region 8, we have a lot of mining sites. 00:00:23.000 --> 00:00:25.000 So I'm going to be speaking about mining sites. 00:00:25.000 --> 00:00:33.000 So a little less organics, but still Csms and advanced characterization techniques that we employed here so a little bit of an outline and we're going to talk about site history because it's long and complicated. 00:00:33.000 --> 00:00:46.000 And so is the Csm. And then I kind of wanted to highlight how we use the traditional data to evaluate whether groundwater surface water reactions may be important. 00:00:46.000 --> 00:00:54.000 And then we use those to develop basically the data quality objectives for our groundwater service water investigation and some of the tools and results from that investigation. 00:00:54.000 --> 00:00:54.000 And then how that affected our Csm. And where we're going from here. 00:00:54.000 --> 00:00:58.000 And then what I'm showing in the photo is actually a fault. 00:00:58.000 --> 00:01:10.000 So this is a fractured bedrock environment, at least part of it is, as you'll see, but that's one of the faults very near the site, and that's actually called Arrow Ringfall. 00:01:10.000 --> 00:01:12.000 Okay, so the Bineta Peak mining district. 00:01:12.000 --> 00:01:12.000 I'm not talking about operable Unit 2. But that doesn't matter. 00:01:12.000 --> 00:01:17.000 There's like 300 mines in this watershed. 00:01:17.000 --> 00:01:22.000 This is one of the potential source areas. It's a large mine waste repository. 00:01:22.000 --> 00:01:31.000 It's immediately adjacent to the Animus river, and for those of you asking the Benita Peak mining district site is the site that got listed after the Gold King Incident. 00:01:31.000 --> 00:01:35.000 But this is not about the Gold King mine. This is about a nearby source. 00:01:35.000 --> 00:01:39.000 It is down in the quarter of southwest Colorado. 00:01:39.000 --> 00:01:41.000 And so why were the repositories there? 00:01:41.000 --> 00:01:49.000 Well, because the mill was there. So the mill was built in 1,929 this is a photo of it that you're seeing here. 00:01:49.000 --> 00:01:52.000 One of the really cool features about this mill is I should just look on the screen. Is that the tram? 00:01:52.000 --> 00:02:11.000 Building, which is right here, is still in existence. In fact, the trams themselves are still there, so these cables run like 2 miles up into this Cirque, where one of the mines that fed this this mill, or is located, but it processed or from over 60 mines in this watershed and 00:02:11.000 --> 00:02:11.000 again, there are over 300 so there are other mills as well. 00:02:11.000 --> 00:02:19.000 Yeah. Mill was built in 1,929 and operated until 1,991. 00:02:19.000 --> 00:02:29.000 Okay, so the mill is way over here in this corner I recognize some of these are small, but the impoundments are in orange here, and they were built successively. 00:02:29.000 --> 00:02:38.000 The first one was built in 1935, and he had an impoundment of mind tailings via slurry successively through here down this valley. 00:02:38.000 --> 00:02:46.000 And there's there's a number of things going on here, including multiple sources and a complex Csm, but I just kind of wanted to delay the groundwork. 00:02:46.000 --> 00:02:49.000 I know there's no scale here the town of Silverton is down here. 00:02:49.000 --> 00:02:55.000 This is like 3 miles in the yellow hashed area that we're looking at here for some general sense of scale. 00:02:55.000 --> 00:02:59.000 It's quite a large site. 00:02:59.000 --> 00:03:05.000 And intrepid minor. In 1,875 climbed up one of these mountains and took this photo. 00:03:05.000 --> 00:03:10.000 Can you imagine that back? Then, with prehistoric camera equipment, I shouldn't call it prehistoric camera equipment, but the responsible part in this case actually, geo-referenced this photo. 00:03:10.000 --> 00:03:19.000 And so we have it now to kind of provide some perspective for you again. 00:03:19.000 --> 00:03:26.000 You can see the town of Silverton, a couple miles in the distance, and you can kind of get the footprint for some of these impoundments. 00:03:26.000 --> 00:03:36.000 One thing I want to point out that you can kind of make out in this photo is the topography kind of falls off as you move towards town. 00:03:36.000 --> 00:03:44.000 And it's relatively flat in a relatively wide floodplain here, where the most recent impoundment tailings pile 4 tp. 00:03:44.000 --> 00:03:44.000 4 was built, the river actually had to be moved to put Tp. 00:03:44.000 --> 00:03:53.000 4 in I'm more on that later. But they geo-referenced the part of the river that weren't moved in order to do this geerereferencing work. 00:03:53.000 --> 00:03:56.000 So kind of fun to do your reference in a bleak photo. 00:03:56.000 --> 00:03:59.000 I'd never seen that done before. All right. 00:03:59.000 --> 00:04:03.000 So what do they look like now? Well, this is June. 00:04:03.000 --> 00:04:05.000 This is 9,300 feet. These are full-size trees. 00:04:05.000 --> 00:04:11.000 So you've got like 100 feet of mind waste piled up on what I just showed you. 00:04:11.000 --> 00:04:15.000 There. And yes, it's snowing, and but this, this is actually Tanley's impoundment for. 00:04:15.000 --> 00:04:21.000 And I took this photo. I think this was 2,019, which was a big snow year, but but 2,023 is a big snow year, too. 00:04:21.000 --> 00:04:26.000 It looks about the same we only have to go like a mile up the road, and it looks like this. 00:04:26.000 --> 00:04:45.000 So, in fact, the other direction you go a few miles. It was they bulldozed through 50 feet of snow, so I know those of you that live in California are thinking well, we had that this year, but it's still a lot of snow to manage and that and you know as a person who's got a drilling program. That's kicking. 00:04:45.000 --> 00:04:50.000 Off as soon as we can get up there this year. I'm very excited for the snow to melt. 00:04:50.000 --> 00:04:57.000 Okay, so conceptual site models. That's that's the one of the main topics we're going to talk about here. 00:04:57.000 --> 00:04:57.000 I give a shameless plug to a recent EPA technical guide called Best Practices for psych characterization, and it's really a conceptual site model. 00:04:57.000 --> 00:05:05.000 Guidance, document, I would encourage you to use it. 00:05:05.000 --> 00:05:17.000 This sunrise chart we affectionately call it is included in there as one of the figures, and it's intended to capture 8 of the key components related to Csms. 00:05:17.000 --> 00:05:27.000 We're mostly going to talk about past use, previous investigations and media and transport here today, but you'll see it includes other things like your pathway receptor network diagram. 00:05:27.000 --> 00:05:31.000 Your potential. Future land use potential remedies, etc. 00:05:31.000 --> 00:05:43.000 So when you're developing a Csm document, I would definitely encourage you to look at this and also note this slide shows what the guidebook says or the tech guide says, which is calls this module geology and hydrogeology. 00:05:43.000 --> 00:05:48.000 We recognize that? That's not quite holistic enough. So that's going to be renamed media and transport. 00:05:48.000 --> 00:05:54.000 Moving forward regardless. If you, Google, EPA, best practices tech Ed, you'll find it. 00:05:54.000 --> 00:05:57.000 Okay, so step one of our geology. Introduction. 00:05:57.000 --> 00:06:08.000 This is a big volcanic system. There's like 3 miles thick lava and ashflow tuffs here, but it's very important for this. 00:06:08.000 --> 00:06:15.000 Csm, because our site is shown here in this green box, and it's right along the river and the river formed where it did, because it's right along the boundary of a Caldera. 00:06:15.000 --> 00:06:28.000 In fact, this is nested called Deris, and this quote from Doug Yeager, and both, and Usgs from a document in 2,007, kind of gets at the point. 00:06:28.000 --> 00:06:36.000 These Caldera ring faults and veins, are collaterally and vertically continuous, and they may be important groundwater flow paths. 00:06:36.000 --> 00:06:52.000 So this is something. We went into this one from the very beginning, recognizing that there was potential bedrock groundwater discharge as well as potential bedrock fracture, flow components to this Csm, so what you're seeing here on the photo just as an fyi 00:06:52.000 --> 00:06:52.000 everywhere that's white is like milestick lava, and all the black lines are big. 00:06:52.000 --> 00:07:00.000 Major faults, and then there are lots of minor faults. 00:07:00.000 --> 00:07:06.000 Okay, so back to our study area may fire Mill again up here. 00:07:06.000 --> 00:07:11.000 But really this is 3 different groundwater systems, and maybe that oblique photo from 1,875 kind of makes that clear. 00:07:11.000 --> 00:07:27.000 There's a perch bedrock system up here underneath the mill, and that water discharges to seeps in the bedrock here that are exposed along these couple of there's actually 3 or 4 roads here below the mill that are kind of cut into the bedrock as 00:07:27.000 --> 00:07:32.000 a central groundwater system that's associated with this fairly large tributary called Boulder Creek. 00:07:32.000 --> 00:07:40.000 We're not going to spend a lot of time on that one, but we will spend the fair most of our time talking about the the the Western groundwater system, which is shown here in blue, and it's it's much more loudly continuous. 00:07:40.000 --> 00:07:47.000 It's essentially the floodplain aquifer. It. 00:07:47.000 --> 00:07:56.000 It's connected to the river, and again I mentioned numerous seeps near the mill, but there's also numerous seeps in other places associated with these other groundwater disjarge zones, including this very large one. 00:07:56.000 --> 00:08:02.000 We affectionately called the Red Seep. Because I think you guys can see that maybe it's behind the table. Apologies. 00:08:02.000 --> 00:08:07.000 But the red staining is pretty prevalent there. I've got another photo of it from from down there. 00:08:07.000 --> 00:08:11.000 This one's Google earth. 00:08:11.000 --> 00:08:18.000 So a quick moment on the mill area I show the photo of the mill. 00:08:18.000 --> 00:08:23.000 As I as I mentioned. It's it's based, a closed basin that's kind of perched on top of bedrock. 00:08:23.000 --> 00:08:33.000 And we also see this red Aquitard. That's important throughout the site, because it isolates an upper aquifer that's more contaminated than a deeper, lower aquifer. 00:08:33.000 --> 00:08:45.000 But in this case it's able to spill over that Aquitard and through the bedrock and kind of discharge along the road, as I was mentioning before. 00:08:45.000 --> 00:08:50.000 This is where the bulk of our effort is spent, related to the Western groundwater system. 00:08:50.000 --> 00:08:51.000 I'll show the come. The contaminant concentration data. 00:08:51.000 --> 00:08:57.000 That shows why our focus is here. But I just kind of want to point out that you know, groundwater flow is is mostly parallel to the river. 00:08:57.000 --> 00:09:04.000 Here that was somewhat surprising to me, given just how steep the topography is. 00:09:04.000 --> 00:09:07.000 These mountains are extremely steep. This is a gaining river. 00:09:06.000 --> 00:09:21.000 Here as that kind of had us trying to investigate. Why, it was one of our one of our first clues that that this was going to be a complicated site. 00:09:21.000 --> 00:09:22.000 To be honest, figure figure out there was 3 aquifers, Swiss, maybe our first clue that it was gonna be a complicated site, regardless. 00:09:22.000 --> 00:09:31.000 This is how we began the Taylor, the Western groundwater system Investigation. 00:09:31.000 --> 00:09:37.000 There's a lot on this slide. But this is a historical aerial photo from 1,972. 00:09:37.000 --> 00:09:48.000 And what you see is the former road alignment. Here the former river alignment through here and you can see the current footprint of the impoundment in Orange. 00:09:48.000 --> 00:09:52.000 So they move the road, they move the river in order to build this impoundment. 00:09:52.000 --> 00:09:55.000 You can also see in other areas that were relatively flat. 00:09:55.000 --> 00:09:58.000 Pretty heavy usage, other other tailings, ponds, and processed water ponds, etc. 00:09:58.000 --> 00:10:04.000 So numerous sources. Here, in addition to our site. 00:10:04.000 --> 00:10:21.000 In fact, this little guy is is a pre different mills waste, regardless the the key thing here is that there are numerous side channels, including one relatively prevalent one that appears to be a spring creek and emanates from beneath this tailings of poundment 00:10:21.000 --> 00:10:24.000 4. And I think that this kind of explains that groundwater flow system that we were seeing. 00:10:24.000 --> 00:10:36.000 There's basically a big preferential flow path here that what lets water transport more parallel to the river. 00:10:36.000 --> 00:10:37.000 So I gotta go through some data. Now, this is this is from the top of tailings. 00:10:37.000 --> 00:10:46.000 Impoundment for tp. 4 in. In September, with with beautiful yellow leaves. 00:10:46.000 --> 00:10:50.000 But you can kind of get a sense of scale here. In fact, there's a seat. 00:10:50.000 --> 00:10:53.000 There's a mountainside seee right here that there's a there's a run- control happening. 00:10:53.000 --> 00:10:58.000 The mill is behind the rig. Here! 00:10:58.000 --> 00:11:04.000 Okay, so with mindsights, we often start with surface water because it's easy. 00:11:04.000 --> 00:11:09.000 Right hits cheap, and it's easy, and in this case zinc is our wrist. 00:11:09.000 --> 00:11:13.000 Driver because it causes significant risk to the to the aquatic receptors in the area. 00:11:13.000 --> 00:11:21.000 So we have an overall, site-wide goal to lower the zinc load, which is kind of the sum of concentration. 00:11:21.000 --> 00:11:25.000 Times flow it's concentration. Times flow. Shouldn't call it a sum regardless. 00:11:25.000 --> 00:11:33.000 So we have an overall goal to reduce zinc load in the river, and a couple of things I want to point out as we go through this so this is a profile. 00:11:33.000 --> 00:11:36.000 I'll love multiple server-water Stations. 00:11:36.000 --> 00:11:39.000 We're kind of integrating a bunch of different data here and numerous sampling locations. 00:11:39.000 --> 00:11:45.000 And you can see I've kind of laid out the site map above it on the top. 00:11:43.000 --> 00:11:52.000 A subtle increase in concentrations. Here, in the in the blue line. 00:11:49.000 --> 00:12:14.000 So when we have more base flow, the green line is actually the spring concentration, profile when it's mostly runoff, and you can see there's quite a bit of dilution in the spring, so so the goal is really to reduce base flow and then again, the red seep I mentioned the red seep actually, comes 00:12:14.000 --> 00:12:19.000 in right right here, and you can see associated with the red, seep as well as downgrading the Red Seap. 00:12:19.000 --> 00:12:23.000 Significant concentration increases, and in fact, the bulk of our concentrations increases. 00:12:23.000 --> 00:12:31.000 Come in downstream of the actual impoundments again, somewhat confounding for my Csm. 00:12:31.000 --> 00:12:38.000 Originally, but it makes more sense. Obviously, if we've as we collected additional data, we we did didn't know there were 3 aquifers at first. 00:12:38.000 --> 00:12:41.000 Okay. So again, a busy side. But a lot of groundwater zinc concentrations here. 00:12:41.000 --> 00:12:55.000 So so we started with the surface water. Yeah, we're seeing we're seeing significant increases in zinc concentrations and zinc load in the surface water and and numerous potential sources, particularly on the what we call the right banker in this case, the north side of of this stream. 00:12:55.000 --> 00:13:02.000 And and so we knew we needed to investigate these sources. 00:13:02.000 --> 00:13:02.000 There was also a responsible party involved in the investigation. 00:13:02.000 --> 00:13:14.000 At this point, and so the responsible party started a fairly substantial drilling campaign to to investigate these sources. 00:13:14.000 --> 00:13:17.000 It took multiple mobilizations. This is again, a lot of data. 00:13:17.000 --> 00:13:36.000 But what I really want to point out is you've got basically high concentration zone kind of starting from the Red Sea, which is which is here in this photo and continuing through the flood plain in the general vicinity of that spring creek that I showed before so again, we're seeing 00:13:36.000 --> 00:13:40.000 the greatest groundwater impacts along the preferential pathways. 00:13:40.000 --> 00:13:44.000 The there's little tiny diamonds on here. 00:13:40.000 --> 00:14:03.000 Water, characterization technique. If you're not familiar with poor water sampling, the goal is to get groundwater from the bed of the river so if you're below about 12 inches in depth and collecting a sample in the riverbed, you're most likely getting the groundwater system. 00:14:03.000 --> 00:14:07.000 so the goal is to push in some kind of micro pushpoint in this case, or temporary well or prisometer, etcetera. 00:14:07.000 --> 00:14:24.000 But push in some kind of point to let you get a sample of that, and let's commonly done for risk assessments to help you evaluate risk to Benthic macro invertebrates and other things that live in the stream bed salmon etc. but in this case we're using 00:14:24.000 --> 00:14:27.000 it, to identify groundwater, discharge zones as well. 00:14:27.000 --> 00:14:33.000 Okay, so that's a lot of the site history as as quick as I can work through it. 00:14:33.000 --> 00:14:38.000 Forgive me as it's, you know it's even more complicated than that. 00:14:38.000 --> 00:14:57.000 Of course, regardless. You know what I tried to show there is that because the site is close to the river, because the site was built on top of historic river channels, because the bedrock is a complicated system here and there are numerous seeps as well as the actual investigation results from potentomatic surface maps and surface water and 00:14:57.000 --> 00:15:02.000 groundwater data. We're seeing a lot of indications that there's potential for groundwater surface water interactions here. 00:15:02.000 --> 00:15:06.000 And I'm showing another seep. In this case this seep is significant enough. 00:15:06.000 --> 00:15:11.000 I should have shown a video instead. But it's significant enough to have resulted in them building a culvert for the round. 00:15:11.000 --> 00:15:17.000 They flows several gallons a minute, and it's just upstream of our site. 00:15:17.000 --> 00:15:23.000 Okay. I already mentioned that the Csm is is complicated. 00:15:23.000 --> 00:15:42.000 I also mentioned that there was a responsible party. Fortunately, that lawsuit has been settled, and so now I can talk about this today, regardless that some of the other considerations we had going into the site was that there are lots of other potential sources, including including many on the on the left gank or the South 00:15:42.000 --> 00:15:47.000 side, of the river. In this case there would not have been associated with this responsible party's word. 00:15:47.000 --> 00:15:51.000 Our actions, sources that exist from before their involvement with the site. 00:15:51.000 --> 00:15:58.000 And so. So there was just a lot of reasons to get the characterization to develop a robust Csm. 00:15:58.000 --> 00:16:17.000 And to get the characterization correct. We're also in a naturally mineralized zone, the background loading here is high, and so we need to understand what is coming onto the site from other sources as well as what's coming under the site from potential natural sources and then another confounding thing 00:16:17.000 --> 00:16:24.000 again in the early days was they were pretty limited impact groundwater impacts below the impoundments. 00:16:24.000 --> 00:16:38.000 It's not Aquitard that I alluded to before, that if you're below that aquitar, the water is basically clean, and and most of the wells were were sunk there originally, because they made good water once they got below that, aqua target and so it was it was that 00:16:38.000 --> 00:16:45.000 first round of well installations. Many of those wells are a little too deep to be to be in the area of interest. 00:16:45.000 --> 00:16:45.000 Yeah, so what this figure is actually from a work plan from several years ago. 00:16:45.000 --> 00:16:56.000 But it shows we had moved on to investigating the the, not the impoundments themselves, but the other areas. 00:16:56.000 --> 00:17:08.000 And so that's kind of what these these zones are highlighting, and you'll see that the flood plain area in yellow as well as this other flood plain area and orange those are those are kind of our current area of investigation. 00:17:08.000 --> 00:17:21.000 Regardless. We identified numerous data needs to better refine our Csm and and we set out an A, an investigation to accomplish them via multiple lines of evidence. 00:17:21.000 --> 00:17:22.000 So so one thing we needed was higher resolution, surface water sampling. 00:17:22.000 --> 00:17:27.000 I showed that surface water, concentration, profile that that had. 00:17:27.000 --> 00:17:33.000 I don't. You've got 10 something sampling points in in 3 miles. There! 00:17:33.000 --> 00:17:43.000 Well, we need a greater resolution than that. If we're going to tease apart sources, we also have this question of whether the sources are coming from the right bank or the left bank. 00:17:43.000 --> 00:17:57.000 Did 2 things to address those 2 questions. We did a tracer test to give us better to higher resolution, surface water data as well as equal, discharging increment sampling where we sampled left right and center of the stream itself. 00:17:57.000 --> 00:17:59.000 More about that. And just a second. But we we tried to tease apart. 00:17:59.000 --> 00:18:10.000 Left bank versus right bank sources, and we also recognize that there is very likely seepage below the stream water level right below the stream. 00:18:08.000 --> 00:18:22.000 The elevation, because you know that that's what of our key data gaps was is the bedrock system discharging significant amounts of groundwater and causing loading in this reach. 00:18:22.000 --> 00:18:29.000 And so we we developed a, so we used a technique called fiber optic distributed temperature sensing to identify sampling targets to evaluate that. 00:18:29.000 --> 00:18:42.000 And then also related to the bedrock. There's a potential for a deep groundwater pathway that was kind of alluded to in that Jaeger and Beauv quote that I gave it to early on where these faults are laterally in vertically continuous 00:18:42.000 --> 00:18:51.000 they are potential groundwater conduits. And so we wanted to evaluate whether that what the potential for deep ground water discharge to surface water was. 00:18:51.000 --> 00:18:51.000 And so that was primarily based on the geophysical investigation. 00:18:51.000 --> 00:19:04.000 But also seep sampling. So I gotta step through all of these various data collection efforts so you kind of see what we did and how we refined our Csm. 00:19:04.000 --> 00:19:09.000 As we went. So this is the tracer test, the high resolution, surface water, characterization, work. 00:19:09.000 --> 00:19:13.000 It was a constant rate, bromide, injection. 00:19:13.000 --> 00:19:28.000 I make a bromide solution and dose it into the river at a constant rate I do this at a time of year that the stream is at base, flow we did it in September, so that we're out of the monsoon, season, and in this case because we want continuous river discharge we don't 00:19:28.000 --> 00:19:32.000 want, dilution because we're using the dilution itself to estimate flow so as new water comes into the system, the dilution we can use that. 00:19:32.000 --> 00:19:40.000 It's just mass balance, we use that to calculate flow. 00:19:40.000 --> 00:19:53.000 And then so the stream samples themselves are shown here in the blue squares, and then we also try to characterize as many of the right bank and left bank inputs as we could find and so right bank is shown in red and left bank is shown in green my apologies if you're red 00:19:53.000 --> 00:20:01.000 green colorblind, but north side circles are our right bank and south side the circles are left bank. 00:20:01.000 --> 00:20:07.000 So you can see much greater resolution than the original data set that we had. 00:20:07.000 --> 00:20:13.000 So, some so the goal of that tracer test was to evaluate the potential sources, to identify the potential. 00:20:13.000 --> 00:20:21.000 Sources, and so I'm just gonna start here. What we're looking at is zinc load and the flow is the other direction. 00:20:21.000 --> 00:20:26.000 This time my apologies, but I have a colleague, Rob Brunkel, with the Usgs, who who provided me these figures, and and as a result they go the other direction, regardless. 00:20:26.000 --> 00:20:39.000 The mill side is down here. And the downstream side is up here, and there's few things I want to point out. 00:20:39.000 --> 00:20:52.000 25% of the load run comes from upstream of this site, and another 12% of the load comes in from a tributary immediately upstream of the site. 00:20:52.000 --> 00:20:56.000 So basically 35 plus percent of the load is not related to the site of the total load. 00:20:56.000 --> 00:21:02.000 As compared up here. You can also see significant loading around the places where we have seeps. 00:21:02.000 --> 00:21:07.000 There were seeps near the mill. There's actually some seeps around the central aquifer area. 00:21:07.000 --> 00:21:10.000 This is the red Seep area itself. But the real thing. 00:21:10.000 --> 00:21:13.000 I want to point out is you've got another several significant seeps downstream of the impoundments, including this one that's shown here in the photo. 00:21:13.000 --> 00:21:29.000 It contributes nearly 12% of the load itself looks relatively innocuous, but tailings upon the 4 is actually way back here in the background. 00:21:29.000 --> 00:21:29.000 So you can see again. We're like on a mile and a half downstream of it here. 00:21:29.000 --> 00:21:42.000 So so much of the load is actually coming in well, downstream of the potential sources. 00:21:42.000 --> 00:21:49.000 So that was the tracer test. The main goal there is to get the best flow data that we've ever had, as well as higher grizz solution sampling. 00:21:49.000 --> 00:21:51.000 We also had to evaluate the left and right bank sources, the potential for which ones have greater impact. 00:21:51.000 --> 00:21:51.000 And so we did equal discharge, increment, sampling. 00:21:51.000 --> 00:22:07.000 There, like left Rider Center, may be affectionately known where you're dividing the river into thirds, not by area or with, but by flow. 00:22:07.000 --> 00:22:15.000 And so we go measure the flow, and then estimate how how the river flows, so you can deal with the thaw leg, etc., as you can see in this particular transect. 00:22:15.000 --> 00:22:16.000 The river is relatively, I guess, uniform across the Channel, but that's not always the case. 00:22:16.000 --> 00:22:22.000 It's deeply incised in the bedrock in places. 00:22:22.000 --> 00:22:26.000 It's it's. It's somewhat complicated morphology. 00:22:26.000 --> 00:22:31.000 Regardless. It gives you some good indicators of where your potential sources may be. 00:22:31.000 --> 00:22:38.000 If you're looking at whether concentration is there a concentration gradient across the stream itself? 00:22:38.000 --> 00:22:44.000 And if you've ever played Lafrent and Center, you know, that's all I could think of when we talk about this. 00:22:44.000 --> 00:22:46.000 So anyway, regardless. So these are. This is the equal discharge, increment sampling results. 00:22:46.000 --> 00:23:10.000 Stream center is shown in yellow here, and it basically plots in the middle string left is shown in green, and it largely plots below the other 2 and Streamwright is shown on right so stream right right bank or in this case north north of the river so so it to use the surface water terms I recognize I'm talking to a lot 00:23:10.000 --> 00:23:14.000 of people that do a lot more groundwater work when you're from downstream right? 00:23:14.000 --> 00:23:20.000 Side is stream right right right bank. So apologies as I use those interchangeably. 00:23:20.000 --> 00:23:24.000 I will. I will try to define them as I go. 00:23:24.000 --> 00:23:30.000 We regardless the the takeaway. Here is much the screen concentrations are higher. 00:23:30.000 --> 00:23:37.000 On the right bank than they are on the left bank. Here's another photo of the red steep the from from the actual street level. 00:23:37.000 --> 00:23:43.000 You can really see it's pronounced red Discharge. 00:23:43.000 --> 00:23:43.000 And you can actually see the central locker for groundwater input here. 00:23:43.000 --> 00:23:49.000 So I. So this is this is where the site sources basically end here. 00:23:49.000 --> 00:23:57.000 Everything from 6.5 meters or so downstream is downstream of the sources. 00:23:57.000 --> 00:24:04.000 Okay, so one more look at surface water data that we're gonna change directions again, we're still looking at flow left or right. 00:24:04.000 --> 00:24:11.000 Here we're looking at dissolved zinc again, because it's our primary risk driver. 00:24:11.000 --> 00:24:29.000 But the the key message here is that the right bank sources significantly higher concentrations than the stream, and significantly higher concentrations than the left bank sources which are shown with the arrows that face left in green. 00:24:29.000 --> 00:24:35.000 Okay, so that kind of wraps up the surface water investigation component. 00:24:35.000 --> 00:24:49.000 As I mentioned, we also had a geophysical investigation primary data needs there were to evaluate deep groundwater pathways or the potential for deep groundwater groundwater pathways as well as to potentially map other sources and and then to also identify the potential for seepage 00:24:49.000 --> 00:24:55.000 zones beneath the stream. Yeah, beneath the stream, through the stream bed. 00:24:55.000 --> 00:24:58.000 This data is available. I have many collaborators here. 00:24:58.000 --> 00:25:01.000 I will acknowledge them at the end. Usgs, EPA, so rd, lots of people help me with this. In this case. Usgs has released a data. 00:25:01.000 --> 00:25:12.000 Release on this one. But we did 3 different techniques, fiber, optic distributed temperature, sensor. 00:25:12.000 --> 00:25:29.000 Again, identifying groundwater discharge points with that and the locations where that is shown are in red and green, where red is a right bank or north side deployment in green is a left bank or south side deployment, and again, we were trying to identify secret zones on both banks 00:25:29.000 --> 00:25:32.000 to make sure that we had evaluated it thoroughly. 00:25:32.000 --> 00:25:37.000 Well, also did an electromagnetic survey and a magnetic survey in both those cases they were handheld instruments. 00:25:37.000 --> 00:25:50.000 The the geophysicists followed each other around so the tracks are the same, and those tracks are shown in white, and they also they traced all the way up to the beginning of our of our distributed temperature. 00:25:50.000 --> 00:25:53.000 Sensor deployment, but they're kind of underneath those red and green lines. 00:25:53.000 --> 00:26:01.000 Okay, so the point of the em survey was basically to, or what I should say is an electromagnetic survey. 00:26:01.000 --> 00:26:08.000 Gives you bulk, electrical conductivity. That's that's kind of a combined signal from your poor fluids as well as your geologic materials. 00:26:08.000 --> 00:26:13.000 Geographic Materials. So it's fluids and solids, data. 00:26:13.000 --> 00:26:19.000 We coupled that with a magnetic survey, because that's sensitive to the ferrous solids materials. 00:26:19.000 --> 00:26:30.000 So by looking at the 2, and where they where they may be different, you can evaluate whether you have a potential groundwater source or a potential solid source of your anomalies. Doug. 00:26:30.000 --> 00:26:38.000 I'm looking at you. I'm no geophysicist, so I have many people to think, regardless. 00:26:38.000 --> 00:26:38.000 So you can see you can see all 3 of these instruments shown here. 00:26:38.000 --> 00:26:47.000 So we, you know the a very common electromagnetic survey is the gym, too, and then we use them. 00:26:47.000 --> 00:26:54.000 A magnetometer here, as shown, and then this is fiber optic distributed temperature, sensor cable on a stand-up paddle board. 00:26:54.000 --> 00:26:56.000 And that's how that's how it was deployed. 00:26:56.000 --> 00:27:01.000 And then this is the controller box that makes it go. 00:27:01.000 --> 00:27:13.000 Okay. So I just mentioned that your electromagnetic survey gives you a parent electrical connectivity a bulk, bulk, bulk, electrical conductivity. 00:27:13.000 --> 00:27:21.000 And so what I want to point out is, you have a few anomalies, particularly down here downstream of this empowerment. 00:27:20.000 --> 00:27:41.000 You also see high electrical conductivity near the Red Seap, which is shown here, we see some other moderate electrical conductivity signals near other secret zones as well. Yeah. Near other secret zones. 00:27:41.000 --> 00:27:46.000 When we look at the magnetic susceptibility again, we're looking at the solid material. 00:27:46.000 --> 00:28:01.000 The the main takeaway here is that in that zone where we saw that really high bulk, electrical conductivity, we don't see nearly as much magnetic susceptibility near near as many ferrous materials which suggests that's likely a groundwater pathway so likely 00:28:01.000 --> 00:28:08.000 groundwater impacts, whereas these zones here are likely tailings, deposition areas. 00:28:08.000 --> 00:28:12.000 There's actually a mill here that's likely associated with this one. 00:28:12.000 --> 00:28:14.000 There is tailing deposited here, likely from an upstream mill, or potentially before the impoundments were built. 00:28:14.000 --> 00:28:21.000 This is actually a photo of those ones in the center to tailings themselves. 00:28:21.000 --> 00:28:28.000 The solids, materials themselves and then there's also a pretty significant magnetic anomaly near one of those tributaries that comes in again. 00:28:28.000 --> 00:28:33.000 We're thinking it was transporting tailings, materials. 00:28:33.000 --> 00:28:36.000 So the the real power is combining the 2 and trying to tease apart. 00:28:36.000 --> 00:28:42.000 What's more likely, a groundwater signal from the solid. 00:28:42.000 --> 00:28:49.000 So this, this was. This photo is of the fiber optic distributed temperature sensor. 00:28:49.000 --> 00:28:56.000 Again in fact, it's the whole. The whole team deploying it in one of the tributaries we studied previously where we had to do it by hand. 00:28:56.000 --> 00:29:01.000 I'm sure they were thankful to have the stand-up paddle board this time, because that cable weighed 300 pounds. 00:29:01.000 --> 00:29:14.000 The premise here is that temperature affects the light transmissivity of fibre, optics, and as a result, you can use them to basically get continuous temperature measurements along the cable. 00:29:14.000 --> 00:29:27.000 And we had 3 kilometers of cable that we deployed here at any given time, so characterizing large swaths of river for potential groundwater, discharge phones. 00:29:27.000 --> 00:29:30.000 So I recognize this slide is pretty busy. What we're looking at here are a couple of different things. 00:29:30.000 --> 00:29:38.000 It's it's in the upper panel we're looking at the absolute temperatures. 00:29:38.000 --> 00:29:45.000 At 6, 37 pm. Along a ailometer of cable, and at 6 37 p. 00:29:45.000 --> 00:29:53.000 M. The surface water is warm. Remember, this is deployed in the stream under the water, so the surface water temperatures, warm groundwater temperature is constant over time. 00:29:53.000 --> 00:29:59.000 So the groundwater temperature is cold. Same location 607 a. M. 00:29:59.000 --> 00:30:04.000 The next day. Groundwater temperatures, warm surface water temperature is cold right and you're seeing right. 00:30:04.000 --> 00:30:12.000 The absolute temperature between these is, you've got 5 and one over 2 degrees C at the second panel and 12 degrees C. 00:30:12.000 --> 00:30:16.000 In the upper panel, so that kind of gives you an indication of how much variability we have day to day. 00:30:16.000 --> 00:30:17.000 And that's that standard deviation, that variability is exactly how we evaluate these potential groundwear secret zones. 00:30:17.000 --> 00:30:28.000 So again, the groundwater signal is constant, so places that are groundwater dominated have low standard deviation. 00:30:28.000 --> 00:30:46.000 In fact, it's the standard deviation. Data itself can be used to give you basically used a high-pass filter in this bottom panel to give relative strength of seeps and so you can see, kind of small and medium seeps out here and then a large and in this case this one's actually, off 00:30:46.000 --> 00:30:50.000 the charts very large, seep down below. What's that? 00:30:50.000 --> 00:31:02.000 Say 15. I'm good, so when you do, when you apply those high pass filters, this is the. 00:31:02.000 --> 00:31:13.000 This is the result. Where we identified many, many, many seeps, as you can see, and it's somewhat difficult to see here. 00:31:13.000 --> 00:31:22.000 But you know we had deployed on the right bank and the left bank so so there's more more details to come here about which ones are right bank associated which ones are left bank associated. 00:31:22.000 --> 00:31:34.000 But there are there are numerous seeps in this area but 1 one key takeaway is that they basically end in the vicinity of the red seep, and they start upstream of there. 00:31:34.000 --> 00:31:37.000 If you remember our loading profile and our concentrations, profiles all of our load basically comes in down here below, where there are much fewer seeps. 00:31:37.000 --> 00:31:59.000 So another line of evidence suggesting that the source of load is this groundwater discharge in the in the flood plain area rather than bedrock, discharge upstream, and another photo of our friend the red seep for you guys to get a look at it it's 00:31:59.000 --> 00:32:05.000 pretty significant. We did find that some of these mineral veins and or faults do discharge water. 00:32:05.000 --> 00:32:17.000 Almost certainly many of these seeps are associated with the faults, and there is a well mapped vein through here that we saw some seepage around, so that that did kind of point to I need to do some sleep sampling. 00:32:17.000 --> 00:32:27.000 I mentioned that we have in the plan seep, sampling due to the joys of government contracting network, has not been completed yet, but we, I think we just got our contract awarded, and we'll be doing that work. 00:32:27.000 --> 00:32:35.000 Maybe this year so I'm gonna combine some a little data of the seeps with this, which was basically the forensic data to identify them. 00:32:35.000 --> 00:32:40.000 To identify them and and provide targets to sample them. 00:32:40.000 --> 00:32:40.000 But again, the key takeaway here is that. Yes, there are lots of seeps. 00:32:40.000 --> 00:32:52.000 Yes, the bedrock discharges water, but most of that water is relatively clean. 00:32:52.000 --> 00:32:56.000 This is a, this is this area immediately downstream of the site. 00:32:56.000 --> 00:33:06.000 And when I first came onto the site I was told that this was a natural blog. 00:33:06.000 --> 00:33:12.000 There are multiple lines of evidence. This geophysical evidence that the monitoring well data, etc. 00:33:12.000 --> 00:33:19.000 That suggests this is impacted. Mine water just exposed at the surface here. 00:33:16.000 --> 00:33:32.000 This is this, this is potentially related to where their pump ax system was for the tailing slurry, because they would discharge as a slurry and then pump back the water to the mill to reuse it, and it was very close to this area where the pump ax system was originally 00:33:32.000 --> 00:33:43.000 built. Mineral veins are likely preferential groundwater discharge zones, but the load is likely small. 00:33:43.000 --> 00:33:47.000 And again groundwater seeps are more prevalent above andoundment. 00:33:47.000 --> 00:33:52.000 4. But surface water impacts are prevalent below in pound. 00:33:52.000 --> 00:33:56.000 And then a little a little aside, that I didn't talk about. 00:33:56.000 --> 00:34:10.000 But in the central groundwater system we do have. We saw a lot of magnetic material it suggests there's actually tailings being deposited by that little tributary stream, and again, that affects our Csm because it means we're potentially taking an action. 00:34:10.000 --> 00:34:19.000 That I wasn't previously considering, so I think I think I got. I think I hit on the soup sampling and the need for that plenty. 00:34:19.000 --> 00:34:32.000 But where is still some additional groundwater investigation to work to do both upstream and downstream of the of tilings, appendment for the other impoundments are relatively well characterized, and then there are those tailings depositional areas that the magnetic survey 00:34:32.000 --> 00:34:37.000 identify those also need additional investigation. Again, those are places we can likely take actions right? 00:34:37.000 --> 00:34:46.000 We can dig out those orange tailings that I showed deposited along the flood plain there, and they would likely have a significant improvement to water quality. 00:34:46.000 --> 00:34:49.000 So! 00:34:49.000 --> 00:35:09.000 I talked fast, but I have a lot a lot, a lot of people to thank to help this entire investigation occurred while I was well at the time my daughter was born, so I was not in the field for any of this work, and so so I've got a huge host of people to think namely, Dale workmen with 00:35:09.000 --> 00:35:17.000 EPA's Rd. And Neil Terry, Rob Ruckle and Marty Briggs with Usgs, and and then a whole host of contractors and other support. 00:35:17.000 --> 00:35:23.000 That's a photo of me on top of tailings in palm of 4 in the fall. 00:35:23.000 --> 00:35:26.000 It's pretty. It's really really pretty. 00:35:26.000 --> 00:35:31.000 Oh, sorry! And with that I will take some questions I left you plenty of time. 00:35:31.000 --> 00:35:42.000 He did. Now we'll start in the room. Any hands up in the room oh, go ahead, Poppy, thank you. 00:35:42.000 --> 00:35:47.000 This is a complex surface water groundwater, and even water does sense. 00:35:47.000 --> 00:36:01.000 Still problem that I think you need to do. Contaminant transport using Geo chem models because zinc is impacted by the geochemical parameter. 00:36:01.000 --> 00:36:05.000 It is beard, and then you need to start looking at the source term. 00:36:05.000 --> 00:36:12.000 How it was I did not see how the souls were originated, so I wish you could discuss it. 00:36:12.000 --> 00:36:23.000 I know you cannot talk more about it. So more complex problem, I believe there's lots of more work in order to do some kind of modeling and to try to do monitoring and addiction. 00:36:23.000 --> 00:36:27.000 I think maybe mining also is combined with other kind of minerals that you are looking for. 00:36:27.000 --> 00:36:37.000 That is another factor 2. In our case. We are looking at the norm enrichment of Norman looking at today. 00:36:34.000 --> 00:36:46.000 Thank you. No, thank you. So I really oversimplified the data that we have and the Csm. 00:36:46.000 --> 00:36:47.000 For the sake of time. Maybe I should have built it out a little bit more. 00:36:47.000 --> 00:36:52.000 There's a lot of data related to the source term that we've already collected. 00:36:52.000 --> 00:36:55.000 Leachability of these tailings, etc. 00:36:55.000 --> 00:37:06.000 1 one reason that I'm focused on zinc is because it's basically conservative at Ph is below 10. 00:37:06.000 --> 00:37:25.000 Our Ph in this stream is like 4. So so zinc is easy, because it's not as complex geochemically, you know, less precipitation and reactions happening and and other interactions happening with sync, so zinc is somewhat easier to focus on because it's 00:37:23.000 --> 00:37:29.000 We we have done, and we'll continue to do geochemical modeling equilibrium type modeling. 00:37:29.000 --> 00:37:51.000 We likely will also to pursue additional. You know, transport type, modeling or something too, when we get to the remaining selection phase, because at this point in time it's relatively clear that we're going to need to take an action downstream of tailings impoundment 4 there 00:37:51.000 --> 00:37:51.000 are sensitivities. That's that's immediately adjacent to the town. 00:37:51.000 --> 00:38:00.000 You know, they're we're gonna have to evaluate scenarios to to control the sources far upstream as we can, etc. 00:38:00.000 --> 00:38:06.000 So there's so it's it's complex, certainly, and and yes, I definitely simplified it. 00:38:06.000 --> 00:38:14.000 There were 60 different minds. There are lots of different types of, orres and wastes deposited here, and some of them are more leachable than others. 00:38:14.000 --> 00:38:23.000 Some of them are more important than others, and again, I kind of kind of made, settled, made it simple. 00:38:23.000 --> 00:38:30.000 Alright! I see another hand in the room. Okay, are your optical cables, purchased, and remain in place? 00:38:30.000 --> 00:38:35.000 And how often do you get data? Or they have rental units that you had for a season or so? 00:38:35.000 --> 00:38:36.000 And how does that work? The Usgs owns cables? 00:38:36.000 --> 00:38:42.000 They own a 2 kilometer cable and a one kilometer cable. 00:38:42.000 --> 00:38:43.000 We use an interagency agreement to bring them out to do the work. 00:38:43.000 --> 00:38:51.000 So this deployment lasted, they were actually excuse me, there are actually 3 different deployments to cover that whole. 00:38:51.000 --> 00:39:04.000 Both sides of that whole stream, and and so we deployed them for 40, 48 to 72 h each, and so that data is kind of time integrated over that. 00:39:04.000 --> 00:39:11.000 That said, we're actually planning a long-term deployment Usgs has a research interest in this, and in a different part of the site. 00:39:11.000 --> 00:39:22.000 But there will be a long-term deployment hopefully this summer where we will look at, you know, variability over time in a different wetland complex. 00:39:22.000 --> 00:39:28.000 I see another room oh, maybe one more thing on Chris. The first question. 00:39:28.000 --> 00:39:34.000 There is one, I think, private vendor, that that does fiber optic distribute good temperatures, sensor work. 00:39:34.000 --> 00:39:37.000 But you know I was fortunate enough to have Usgs. 00:39:37.000 --> 00:39:40.000 Kobe. 00:39:40.000 --> 00:39:51.000 Yeah. Great talk. So with the, how are you using temperature to look at the differentiation between groundwater and surface water? 00:39:51.000 --> 00:39:51.000 And I'm assuming you've looked at other water quality parameters. 00:39:51.000 --> 00:40:00.000 Are there any anything shouting out for like Ph or Ec. 00:40:00.000 --> 00:40:12.000 Yes, the short answer is, yes, so temperature is great because the precision, and accuracy of fiber, optic attributed to temperature sensors is really really good. 00:40:12.000 --> 00:40:17.000 And so you can find those really subtle variations with with those with that technique. 00:40:17.000 --> 00:40:20.000 But that's kind of the like you. You bring that toy out when you've tried other things first. 00:40:20.000 --> 00:40:33.000 Basically right? So I would certainly recommend a different reconnaissance method if you're kind of contemplating something like this, based on electrical connectivity or even handheld temperature. 00:40:33.000 --> 00:40:39.000 So you can kind of walk around a stream bank and poke a conductivity or temperature probe in in and around the sediments as you work around and do, and get a rough feel at the same time. 00:40:39.000 --> 00:40:49.000 In this case we really needed to be as accurate as possible. 00:40:49.000 --> 00:40:55.000 Okay, because it is a complex political site. So we were trying to get it. 00:40:55.000 --> 00:41:01.000 We're trying to get it correct. Choose my words carefully. 00:41:01.000 --> 00:41:19.000 Alright. I see a hand in the back, Lucy, there should be a mic, maybe that black Puck at the table. If not, let me get you a microphone. 00:41:19.000 --> 00:41:26.000 Oh, have you contemplated doing thermal infrared like drone surveys of this site? 00:41:26.000 --> 00:41:33.000 We did walk with flea cameras. We walked, looking for for groundwater district zones. 00:41:31.000 --> 00:41:44.000 Are are relatively easy to identify in this area. Because, yeah, there's snow on the ground in June, right? 00:41:44.000 --> 00:41:46.000 I mean, it was relatively easy to find the things discharging about the surface. 00:41:46.000 --> 00:41:55.000 So the real goal of the fiber optic investigation was to identify groundwater discharge below the water surface. 00:41:55.000 --> 00:41:57.000 But yes, we didn't do it with a drone. 00:41:57.000 --> 00:42:02.000 We walked it with clear cameras. 00:42:02.000 --> 00:42:08.000 Yeah. Erica, I think. Hi, this is Erica Elfo. 00:42:08.000 --> 00:42:23.000 This is a great talk I think it's really for me, from a geochemical standpoint, it's a piece that often gets missed in Csms, especially when we're looking at points of compliance and groundwater surface water interactions and how dynamic those systems can 00:42:23.000 --> 00:42:33.000 be, and how dynamic changes over time! Weather, or not, it's a gaining stream or a losing stream, or even points where groundwater is constantly discharging to surface water. 00:42:33.000 --> 00:42:54.000 You still have these interactions that have significant fluctuations in water levels which then have significant fluctuations in groundwater, concentrations, especially when you're pointed compliance wells are located along these surface water bodies and so for me, it's always a challenge to how 00:42:54.000 --> 00:43:02.000 do you? From a temporal, from a larger scale, long-term, temporal manner, how do you account for this? 00:43:02.000 --> 00:43:04.000 Not only in your Csm. From a geochemical standpoint, but also in how do you, when you're looking at performance? 00:43:04.000 --> 00:43:14.000 Remediation and achieving Raos. How do you account for that? 00:43:14.000 --> 00:43:21.000 I wish I had a good answer for you. You know I'm the EPA technical guys. 00:43:21.000 --> 00:43:25.000 My answer is more data, of course, but I recognize that's not always practical. 00:43:25.000 --> 00:43:45.000 We we have found an this site. It is extremely dynamic you, there's a lot of intra-annual variability and so so we try to use a minimum of 3 years and 6 sampling events worth of data to make any decisions at this site, at all especially risk-related decisions but we know that that's 00:43:45.000 --> 00:44:02.000 not sufficient, either we're just fortunate to have had the 2 largest snow years ever in our study time period, as well as the least snow year ever in our study time period, so we were fortunate to be able to have a pretty good brackets on our Max and men I guess load 00:44:02.000 --> 00:44:08.000 in the surface water. But that was luck. That was just weather related. 00:44:08.000 --> 00:44:10.000 Luck in our case. So so I wish I had a good answer for you. 00:44:10.000 --> 00:44:14.000 We are contemplating a point of compliance. 00:44:14.000 --> 00:44:15.000 Approach here, downstream of this in the surface water, because there are just so many other potential sources. 00:44:15.000 --> 00:44:26.000 And it's going to take a holistic watershed approach in order to remediate this site just to oh, sorry! 00:44:26.000 --> 00:44:42.000 Just a follow-up. I mean, there are some ethics that leave a py at some EPA sites where you, from a temporal standpoint, you kind of account for all of these different covariates that impact your groundwater concentrations, where you're so surface water concentrations 00:44:42.000 --> 00:44:47.000 over time. So there are some methods that you can use these multiple regression covariate type methods that are a little bit more simplistic than developing large-scale groundwater models. 00:44:47.000 --> 00:44:56.000 But there are more data. They rely more on the actual data as opposed to modeling. 00:44:56.000 --> 00:45:05.000 But there are some methods, but still it's tricky to capture all that, and often I find that it's not captured. 00:45:05.000 --> 00:45:12.000 Thank you. I will catch you with Frank. I'd love to hear a little more about that.