Rocky Flats Site, Colorado, Tour – Woman Creek Point of Compliance (WOMPOC)

I'm standing at the Woman Creek Point of Compliance, known as WOMPOC, W-O-M-P-O-C, L-O-N, acronym. This is one of our two surface water points of compliance. The other one is WALPOC, or the Walnut Creek Point of Compliance, on the Walnut Creek drainage. What you see behind me is a flume. It's the concrete structure down there, and the two boxes are the automated sampler equipment. If you look carefully, you can see next to the sampler on the right a very low precipitation gauge. It's about that high, white with a caramel-colored top. The way this works is the sampling equipment inside the stations are always on, always running, 24-7, 365, or 366. They are not shut down. At WOMPOC, we monitor for plutonium, americium, and uranium. This is the combined surface water from Woman Creek, which is the drainage on the right with most of the trees, and the flow from Pond C-2, which is on the left, with just the one tree and another sampler close to the hillside there. That hillside is actually the dam for Pond C-2, which you can't see. You can see the dam, but not the pond. In this dam are some typical piezometers used to measure the water level within the dam. It's an earthen dam, as the other dams are on Rocky Flats. So, flow from the Woman Creek and C-2 join just upstream of this location, WOMPOC, and the water is sampled automatically through the sampling equipment that's in the little boxes over there. It's flow-paced monitoring, which means that as the flow increases, the sampler is collecting a small portion of that flow more frequently. What we do is, based on our historical knowledge and a statistically derived number of samples that we'd like to get for a given year, to provide adequate statistical confidence in our data, we set what's called the pacing on the sampler to collect a sample for a given flow regime. What that means is, in the spring, when we have a lot more water, there's a lot of water flowing through the flume here. This is just a hypothetical number, say it's 2,000 gallons a minute. Well, if you program the pacing to take a grab, a sample, aliquot, a small volume of that water, every 2,000 gallons, then in the spring, 2,000 gallons will be coming by fairly quickly and it'll keep collecting an aliquot, a grab, putting it in a big bottle inside the sampler. What happens is, as the flow increases, the amount of time between it collecting a small amount is reduced, so it's collecting more and more frequently. And then as conditions dry, it'll slow down so that it continues to collect a small amount of water for every equal interval of water, equal volume of water that has flown through the flume. We monitor this from the office and on our phones via telemetry. That's what the antenna attached to the next to the two samplers is for, so that we can collect those data remotely. And then we know how the sampler is working, how full the sample bottle is, which is a 40-liter carboy, and we can tell when it's time to come out and exchange those bottles. If we have a flood condition where we can't get out here in time to pull that bottle, which happened in 2013, and parts of Indiana where the culverts rotted through and cars fell into the drainage and the road was closed and Highway 93 was closed, so you physically weren't able to get out here, you weren't allowed to. In an instance such as that, we have the second box. There's a similar sampler inside that, but it's set at a different pacing. So again, hypothetically, if the one everyday normal use all conditions sampler has filled up because of these unexpected flood conditions, and say it's programmed to collect a grab every 2,000 gallons that passes through the flume, the other sampler may be programmed to collect a sample every 10,000 gallons that passes through. So if the one that's used routinely is now full, the second one will take over. And since it's set at a pace of so much higher, every 10,000 gallons, then it's collecting grabs more slowly. And in that way, this flood won't overwhelm it as quickly. And we're out here every workday, and you know, in conditions like the flood of 2013, when that was physically impossible until Colorado Department of Transportation escorted us out to our gate. But that was only like two days or so after the flood conditions had ended. And had that second sampler been on station and enabled, we wouldn't have missed any sample. That's why that second sample's there, is because we learned from that flood, and we put that second sampler there. We have a second sampler at Walpok as well for the same reasons. So we monitor for plutonium, americium, and uranium here. And doing that in flow paste method is much more effective than if we came out and just filled bottles manually. First, because you're getting this 24 hours a day, all conditions sample. So whether it's raining, or snowing, or really, really hot or windy, when humans wouldn't necessarily want to be out here, this thing is still working. And secondly, the flow or the concentrations of say plutonium and americium will vary depending on the environment, the climatic conditions differently than uranium will. Uranium can be present dissolved in the surface water and dissolved in groundwater. Instead, plutonium will only flow when the surface soil is moving, because it's only soluble at extremely acidic pH, extremely acidic conditions, which we don't get out here at Rocky Flats in nature. So being that this location is downstream from the 903 pad and the 903 hillside, and those soils were cleaned up to 50 picocuries per gram, that's a measure of radioactivity. So the plutonium and americium move under different environmental conditions than uranium does. Uranium will be dissolved in the groundwater and surface water, whereas plutonium sticks to silts and clays and therefore only moves when those silts and clays move. That happens when we get a heavy rainstorm, heavy runoff from snow, hailstorm, something like that, that pummels the surface of the ground. And we know that there's residual low levels of plutonium contamination basically east and southeast of the former 903 pad. It's only at a picocury per gram or two picocuries per gram, something on that order. The cleanup standard was 50 picocuries per gram, but our standard for surface water is 0.15 picocuries per liter, and that's how much radioactivity can be in a liter of water. So cleaning up to 50 picocuries per gram of the soil does not necessarily protect surface water quality. That's why we maintain the erosion controls and the vegetation so thoroughly and actively. Uranium doesn't move during those conditions any more or less. Instead, since it's dissolved in the surface water and groundwater, under a heavy storm, that tends to dilute the concentrations of uranium. So this heavy storm that may make muddy runoff if it's eroding a lot of sediment can carry a lot more plutonium and americium, but it would dilute the uranium. And then as the flow goes down and the plutonium and americium sticking to those soil particles are no longer present, well, the uranium concentration will appear to go up, and that's because there's less flow. It's being fed by the groundwater, which has higher concentrations of uranium here due to the natural uranium in the sediments and in the rock in this area. What you can see here on the C2 dam, you've got the piezometers, and for station Wumpok over here, we are fully off the grid at Rocky Flats. You can see the high voltage transmission line that basically goes over the dam, but that's just for transmission of electricity. We don't get to tie into that. Instead, we run off the batteries that are inside the sampler and the solar panel that recharges those batteries. As I said, we monitor americium, plutonium, and uranium at this location, and the concentrations, the activities have all been well below our standards. I mentioned that it's 50 picocuries per gram of soil was the action level for surface soils in the cleanup, and 0.15 picocuries per liter is the standard that applies here at Wumpok, but we've not come close to that, and that's the plutonium, what we call the PU standard. As far as uranium, it's 16.8 micrograms per liter, which is a mass-based concentration. It's a ppb, 16.8 parts per billion equivalent, and we haven't come close to that either. We're way below that. Walking across the dirt road, you can see that the downstream portion of Woman Creek is right now, first of all, just as the upstream portion, there's no flow, but it's very heavily vegetated. You can't see the gravel bed or anything due to all of the vegetation, and downstream is Stanley Lake, which you can see in the distance. Between us and Stanley Lake is the Woman Creek Reservoir, also known as the Stanley Lake Protection Project, which DOE built to contain water from the Woman Creek, and from that reservoir, it then is discharged so that it bypasses Stanley Lake.