Rocky Flats Site, Colorado, Tour – The Notch

Behind me is the South Walnut Creek drainage and that's this the stream that comes through here it's can't you can't even see because this was taken in the mid 90s 1994 time frame and so at that time frame the the drainage was there's part of it here and there's part of it down here but it's really hard to tell some things that you can see the shed is in this isn't the shed because this predates building of the shed but that's where the shed is located and there are four tall conifers here that you can see right over there and the dirt road that's just to the left of those four trees used to be paved and used to cross South Walnut Creek obviously it no longer does so this with the blue roofs is the former sewage treatment plant so Rocky Flats had a water treatment plant that would make potable water and then and make water for all the processes and so forth and then all the used water the sewage sewage water that was generated on site and so forth would be routed to the sewage treatment plant which would treat it and the the former solar evaporation ponds and the former 903 pad that are other stops on this tour so moving farther down past the elk you can see a the backside of a small solar array and a couple of a couple of ground level features that have railings surrounding them those two features are the former treatment cells for the mound site plume treatment system which was installed in 1998 it was at that time innovative technology the treatment basis was zero valent iron which is a granular media also known as zvi and in just up uphill from that you can see what look like well heads and those are actually marking the the center of a an interceptor trench where ground water is intercepted because the ground water will flow down towards and discharge into South Walnut Creek if it's not intercepted and that ground water has chlorinated solvents in it above the standard so we need to intercept that water and treat it it was the mound site plume treatment system and it had the zvi it was totally gravity driven passive treatment the solar array was not there it was just a flow through media but it did not maintain treatment to the required levels after closure in part due to tying in a second source area in other words there was another area near there an oil burn pit that where some chlorinated solvents had been disposed and although the the source material was excavated there was still residual chlorinated solvents in the subsurface and so after that was backfilled the there was a gravel trench routed to the collection feature for that treatment system which which dramatically increased the flow volume and flow rate through the zvi and also increased the concentrations of these chlorinated solvents and because the zvi treats water by one of the most important things is is contact time now you're pushing more water through the same amount of zvi so there's less contact time with that iron and as a result there was less treatment so we were no longer meeting the standards and as a result what we did was do some prototyping here to look at whether we might easily add air stripping which is another treatment mechanism where you you force air through the water to take the the dissolved organics out of the liquid phase in other words it's no longer in the water it's not dissolved in the water instead it's in the air that has been pushed through that water and then exhaust it and so that was one of the things we tried we tried it more more thoroughly down the valley here at the east trenches plume treatment system which is another stop on the tour and that was also originally passive flow through tanks of zvi it was never as effective at treating the chlorinated solvents as at the mound because the the concentrations there the the flow is is greater and as a result it was not as effective so what we did is between the prototyping of our air stripping at the mound and additional prototyping at the east trenches plume treatment system or etpts we eventually went to what you see now which is a connex with a lot of solar panels attached to it inside that connex the cargo container are a number of batteries and so the batteries power an air stripper that we'll see on another stop on the tour the reason for these two systems is it's the conceptual site model for the entire site rocky flats is predominantly was predominantly built on the rocky flats alluvium pediment surface which we're standing on up here it's the basically what others might call the the the mesa tops and the rocky flats alluvium it's a variable thickness it's over 100 feet west of the rocky flat site and where we're standing now it's maybe a dozen or 20 feet thick the groundwater is flowing in that along the top of a a much lower permeability unit it's lower permeability meaning it the groundwater doesn't want to well it doesn't flow vertically down into this material because it's a dense clay stone clay is is very good at resisting water flowing through it and so the water flows laterally through the rocky flats alluvium along the top of that clay stone unit that's underground and then when it gets close when that groundwater gets close to a drainage because it's it wants to flow downhill which is normally west to east but as it nears a drainage it peels off down the hill towards that drainage and it'll discharge to the surface water and therefore with with a contamination from the mound site plume contamination from the east trenches plume which is added to by the 903 pad plume these two treatment systems would were installed to intercept that contaminated groundwater and treat that contaminated groundwater so that it wouldn't discharge and contaminate south walnut creek so that's the way the hydrology works at rocky flats the source areas for these at the in terms of the mound which is now in incidentally it's called the mound site plume collection system because we no longer do active treatment there instead we reconfigured that to transfer the water from that's collected there down the valley to be treated at the east trenches plume treatment system or etpts by that air stripper that air stripper is now treating the contamination from the east trenches plume the mound site plume and the contaminated water from that oil burn pit that i mentioned and all three of those source areas have the same types of contaminants that are these volatile organics meaning they readily evaporate very easily evaporate hence air stripping being so effective a treatment method so those two treatment systems well that were installed to protect south walnut creek water and the source areas for the mound site plume now collection system the mound site source area is on the hilltop the pediment surface just uphill from that low of that line of small juniper trees there and the oil burn pit source area is just to the right of of that there's nothing remarkable as a landscape that i can point to but it's to the right before you get to that riprap channel which is one of our functional channels and then as far as the east trenches plume the source area is across from where we are there are some trenches hence the name east trenches plume there were several trenches and dug on that pediment surface to dispose of various wastes like sewage wastes and laundry wastes and other wastes this was back in the 60s time frame when digging a trench and disposing of that type of waste was standard practice across the country and across the world probably still standard practice in some areas of the world we know better now not to do that but back then that's what you did and and obviously as evidence came that we were contaminating the surface water here it became obvious that we needed to deal with that contamination and so that's why these two treatment systems were installed at the mound the collection trench can can be kind of approximated by the those stick ups just past the the railing the silver railings you'll see some what look like well heads and those outline the collection trench it's only a couple hundred feet long at that particular unit the east trenches plume treatment system has a roughly a thousand foot long collection trench approximately underneath the dirt road behind me and the way those are fashioned it's a perforated pipe so that it'll collect the groundwater and that perforated pipe is bedded in sand and gravel so that that's also a permeable media that can act like a pipe and then on the down gradient side meaning closer to the surface water there's a plastic barrier a thick plastic barrier so that even even if the if the water isn't captured by the pipe or the gravel it'll hit that plastic and be diverted down the hill down gradient to be captured and treated at the east trenches plume treatment system the water that's treated is then discharged to the surface water behind those or to the subsurface behind those cottonwoods there and that's the way the treatment systems work how do we know whether these treatment systems are working and what the water quality is like we collected a lot of samples all in accordance with the rocky flats legacy management agreement or rifflema attachment two that has the locations the frequency of monitoring the analytical suite in other words what chemicals are to be analyzed by the laboratory we also only submit samples to qualified labs that pass epa requirements and they're also audited periodically through a program of lab auditing to ensure that the labs are performing properly their equipment is kept up to specs their cap the equipment is calibrated right so on and so forth so everything from the laboratory analysis end is is very sound what about the sample collection we wear specific ppe or personal protective equipment both to protect the worker from any contaminants that might be in the water should they splash some water on their hands or what have you but also so that whatever might be on their hands doesn't go into the samples a sample to be analyzed for these organic compounds for example if the samplers got lotion on their hands and the water gets on their hands and then into the sample that can throw off the sample concentrations so that it no longer represents the groundwater it's contaminated by the samplers hands but that kind of information won't make it through to the data user and that can result in in bad decisions because the data are bad so we we take very careful measures to make sure that the data we get are high quality and the analyses that are performed are also high quality to further check on that we collect what are known as qaqc or quality assurance quality control samples this includes sample duplicates that's field duplicates where one sample is collected and a second sample is collected exactly the same way same size bottle same time and both samples are submitted to the lab and then the results are compared we also collect what's called an equipment rinse blank which is where the equipment has been cleaned what we call it is decontaminated or deconned so that we know that that can that equipment is now ready to be sampled at the next to be used at the next sampling location but for an equipment rinse blank after we decon it we will pour clean water distilled or deionized water that's free of the the chemicals that are being analyzed by the laboratory we pour that water over the equipment and collect it in a laboratory for the the analytes of interest and from that we know whether the equipment is contributing contaminants to the sample and all of these measures are undertaken so that the data that we get from a specific location can be shown to be representing the water at that location at that time because again we don't want to make bad decisions so that goes to both the groundwater and the surface water and surface water again is the reason we're treating the groundwater and also basically the reason we sample the groundwater because the groundwater contamination is only in the shallow interval that's in that rocky flats alluvium and the shallowest claystone where it's been weathered and then that would discharge to surface water and so that surface water needs to also be monitored the white box down there is a surface water monitoring station it's a it's it's classified in the rifflema as a point of evaluation or poe and that's gs10 and it conducts flow paced monitoring meaning that when there's very slow moving flow not very much flow the stream is is near dry it only collects a little bit of water into its sample container infrequently very separated by a long amount of time and it's it's programmable we don't program it for the time we program it for the flow and i'll describe that more fully when we're at the location on the tour as the flow increases say there's a rainstorm and now the stream is is really gushing in order to have a flow paced sample the the let's say it collects a sample every every hundred cubic feet that passes by there as the water level increases and the flow increases those will be collected more and more frequently because the hundred cubic feet are going by more rapidly than when it's nearly dry and it's just a trickle so that's how we get the sample to be representative of all the conditions for the time in which that particular large bottle was in place in the sampler and then when we swap out bottles we take the filled one out and we put in a clean previously decontaminated bottle we can reprogram that sampler for a different what's called a different pace in other words how what instead of maybe a hundred cubic feet maybe it's 120 cubic feet if we're getting into a wetter time of year we have many many many years of data on which we can base these predictions and of course they're based on normal flow normal precipitation conditions that we have come to expect based on the data that we've got over the seasons and the past decades sometimes those predictions are inaccurate like the 2013 flood when we got up in September which is usually a dry month we got something like a 500 to 1000 year flood here so we we can reset the pace to accommodate different seasonal flow conditions and at this particular location we analyze for plutonium americium uranium and then four different metals and it's important that we do the the flow paste monitoring rather than go down and just hand collect a bottle every quarter because that would be on a day like today not in the middle of the night when we're in a hailstorm and that hailstorm can cause soil to move and because the soil is moving and because plutonium and americium stick to soil particles that's when your plutonium and americium might be moving into the surface water and might be flowing by gs10 so we want to get that sample we want to get that water as part of our sample we're not going to have somebody come out here with a bottle every time there's a storm in the middle of the night so that's why we have these programmable samplers so that's how the plutonium and americium move is in heavy downpours and and in hailstorms that kind of thing it doesn't move in the groundwater it sticks to soil particles and the groundwater doesn't transport soil particles but uranium on the other hand will dissolve and therefore when there's a larger fraction of uranium of groundwater in the flow which is typical of our winter conditions aside from snow melt events if there's not a lot of snow melt then the water in that drainage is going to be predominantly groundwater and that will have more uranium in it so again that's going to be maybe at times when you wouldn't have somebody out here hand collecting a sample same thing with the metals another way we know how this is working is through our telemetry all of the data well the sample performance the flow flow rates the status of the carboy the large bottle in that structure and so forth is collected and beamed back and accessible by us at the office or on our cell phone through a router that's over here all of this is on telemetry there's a little antenna that you might be able to see it's got a rain gauge mounted towards the base of it it's right on top of that little wall the rain gauge is white and there's a black pole that's an antenna and the signal from that particular sampler is relayed by this router to our office and via cell phone so that we can get it on our phones as well so that way we know the conditions at the sampler we also know a lot about our treatment systems they're not sampled remotely the samples aren't collected automatically like it ground at the surface water but we know if if say the air stripper has stopped working or something which it doesn't do but we can monitor the flow rates the water levels that kind of thing remotely we don't have to come out here and visibly check and then the last thing I'll say about this South Walnut Creek drainage you can probably see that there are some unusual features here there used to be five ponds a total of five ponds in this drainage and from this vantage you can see four of the previous ponds their dams have been breached and in those breaches it's a it's a basically it's a a notch through the dam that's cut to meet specific engineering designs those breaches have these grouted rip rap it's they're big boulders that are cemented in place and so there's no more dam there instead it's wetland behind each of the the breached dams and those used to be ponds so this was former pond b1 b2 b3 and then just past the cottonwoods there was b4 pond b4 pond b5 is farther down the drainage it's a terminal pond that still exists and eventually the plan is to breach the terminal pond dams as well but these dam breaches have performed very well they were all done after closure through a rigorous process of meeting with the regulators to make sure that everybody was accepting the path forward to breach the dams and then designing them to meet the state engineer's requirements so that the dam breaches could could be created