The Recent Flood & Plutonium at Rocky Flats: Is the Current DOE Rocky Flats Manager Confused?

See the previous entry in this blog for a Boulder Weekly article about plutonium and the recent flood. This brief letter to the author of that article responds to a quoted erroneous statement made by the current manager of the DOE portion of the Rocky Flats site.

Joel:

Your recent Boulder Weekly article, “Flood Raises Questions at Rocky Flats,” says Scott Surovchak, the Manager of the DOE portion of the Rocky Flats site, disputes claims Marco Kaltofen of the Boston Chemical Data Corp. made in a report in early 2012 giving results of soil sampling he had done for the Rocky Mountain Peace & Justice Center on the eastern edge of the Rocky Flats site along Indiana St. Kaltofen reported that according to his work the plutonium levels in this area were just as high in 2012 as they were 40 years earlier before any cleanup activity had happened at Rocky Flats. He suggested that water leaving the site as a result of the September flood was quite possibly contaminated with small quantities of plutonium. Surovchak disputed this claim, saying (according to your article) that Kaltofen’s sampling “was done with an optical rather than radiological analysis and was therefore inappropriate for determining the true levels of plutonium in surface soil.” Kaltofen responded: “The plutonium was determined by both electron backscatter and gamma spectroscopy. Both are standard methods. Neither is an optical method.”

Clearly, DOE Manager Surovchak either doesn’t know what he is talking about, or he is deliberately demeaning an experienced soil sampler. Neither enables the public to trust what a DOE official says.

LeRoy

September 2013 Flood and Plutonium at Rocky Flats

Boulder Weekly, Thursday, October 10,2013

FLOOD RAISES QUESTIONS AT ROCKY FLATS

By Joel Dyer

Photos courtesy of the EPA

Rocky Flats in 1995, prior to being remediated.

Like the rest of the region, the rain started soaking into the ground at Rocky Flats on Monday, Sept. 9. By the following Wednesday night, the ground was fully saturated and the flooding began in earnest, with runoff from the hills, gullies and holding ponds at the site, filling North and South Walnut Creeks as well as Woman Creek beyond their capacities.

As the water finally began to recede, the debris caught in the fences above the usual creek banks bore witness to the unprecedented water levels that had swept through the area between Wednesday night and Saturday morning.

The water washing across the four square miles of land at Rocky Flats had raced down the creeks and dry washes and off the property towards the lakes and housing additions to the east, closing Indiana Avenue and raising concerns and more than a few questions.

Was there contamination in the floodwater and, if so, what kind and at what levels? And is the threat of contamination spreading due to the rains now over?

At least some of the answers to these questions will likely come sometime around Oct. 11, when the Colorado Department of Public Health and Environment (CDPHE) estimates that it will get back test results from two labs that examined samples from the 10 surface-water monitoring stations at the Flats, most of which are located along the Walnut and Woman creeks. But will these test results answer all the questions being raised? Considering the long history of Rocky Flats and the ongoing, 30-plus years of controversy surrounding its contamination and cleanup, it seems unlikely.

Rocky Flats is a former nuclear weapons production facility just south of Boulder that operated from 1952 to 1992.

At one time, prior to its closure and remediation, the former plant and the lands surrounding it were considered one of the most contaminated places in the world. The area’s ground and surface waters are still being monitored today for radiation, and there are measurable levels of plutonium, Americium and uranium in some locations at the site that exceed Environmental Protection Agency (EPA) standards.

Other contaminants at the Flats include PCBs and carcinogenic BTEX contaminants, named for benzene, toluene, ethylbenzene and xylene.

In addition, groundwater recovery systems designed to capture uranium and nitrate contamination that has leaked into groundwater are in place to strip out the contamination before allowing the groundwater to be released into the area’s creeks and lakes.

And finally, critics of the government’s remediation of Rocky Flats, including the Rocky Mountain Peace and Justice Center, claim that plutonium contamination well above normal background levels can still be found in the surface soils at Rocky Flats in widespread locations across the area, including, according to tests commissioned by RMPJ in 2012, outside the site’s eastern boundary along Indiana Avenue, where a privately funded toll road, the Jefferson Parkway, has been proposed for construction.

The following is an overview of what is known to have occurred at Rocky Flats due to the flooding, concerns about what may have occurred, and possible future problems that could arise as a result of the September floods.

* * * *

Shortly after the flood, several news outlets, including Denver television station Fox 31, reported that a cap covering a landfill at Rocky Flats had cracked due to the flooding and that emergency repairs were under way even as the rain was falling. No further details were offered.

Rocky Flats in 2007, after cleanup. | Photo courtesy of the EPA

The station, aided by Dr. Jeffrey King of the Colorado School of Mines, later tested for radiation along the creeks where the water coming from the Flats had passed and reported that nothing alarming was found.

As for the cracked landfill cap, there are two former landfills at Rocky Flats. One is known as the original landfill (OLF) and the other is referred to as the present landfill (PLF).

According to Carl Spreng, Rocky Flats coordinator for the CDPHE, both of the landfills are capped, but with differing types of caps for different purposes.

The PLF cap is a combination of clay and waterproofing materials designed to prevent rainwater from infiltrating the landfill beneath the cap, an outcome that would likely cause groundwater contamination that could spread from the PLF, eventually making its way into area surface waters.

The primary contaminant of concern in the PLF, according to Spreng, is benzene, one of the BTEX compounds. As a result, a waterproof cap is needed because BTEX contaminants are easily transported long distances in groundwater. Spreng says that no plutonium or other radioactive contaminants are in the PLF, and that the cap on the PLF was not the one breached during the flood.

The top of the OLF is what actually cracked. Although news reports referred to a “cap on a landfill,” what actually cracked was not a cap but the cover over the OLF, which is made of earth. According to the Department of Energy’s Rocky Flats Site Manager Scott Surouchak, “cap” is a term describing a federally required waterproof covering under the RCRA laws such as the one over the PLF. He says that the dirt top over the OLF predates the Resources Conservation and Recovery Act (RCRA) and can only be referred to as a “cover.”

Spreng says the OLF cover is made of dirt and was not designed to be waterproof. The primary contaminants of concern in the OLF are polychlorinated biphenyls (PCBs). PCBs are not easily soluble in water and tend to cling to soil. They can migrate, however, in water along with soil that is being swept away. They are also easily re-emitted to the air and can travel long distances before settling or being driven down by rain, according to the EPA and the Oregon Department of Environmental Quality.

This explains the need to quickly repair the OLF cover following the flood. Spreng says that the OLF cover will likely be re-engineered in coming weeks because it was already sagging in some spots.

Surouchak says that the Department of Energy has no plans to test for potential PCB releases because the levels in the OLF years ago were already very low and looking for PCBs would be pointless.

Another potential, but by no means substantiated at this time, source of contamination resulting from the floods could be the release of sediments from the three remaining holding ponds at the Flats, which are located on North Walnut, South Walnut and Woman Creeks.

According to a 1996 technical report titled Characterization of Releases to Surface Water From the Rocky Flats Plant, in 1972-73 the three holding ponds were drained and reconstructed. During this draining process, the levels of radioactivity found in the creeks increased 80-fold as a result of sediment-heavy waters containing plutonium being released from the ponds to the creeks.

Plutonium is heavy and not particularly water-soluble, so it tends to collect in sediment at the bottoms of ponds and creeks, or in the sediment of the lakes where the creeks eventually deposit their waters.

This explains why there are still low levels of plutonium in the top 12 inches of sediment in both Stanley Lake, which receives water from Woman Creek, and Great Western Reservoir, which gets its water from the two Walnut Creeks. Neither reservoir has been used as a city water supply since the 1990s due to the discovery of contamination originating from Rocky Flats.

During the September floods, the water levels in the three current holding ponds rose extremely fast and approached overtopping the spillways but did not do so, according to Spreng.

“It reached up to the overflow but then drained off quickly without ever going over. But it doesn’t really matter, the water all goes to the same place anyway. It was drained off into the channels to the creeks where it is monitored,” he says.

The question of whether or not the rapid rise and equally quick draining of the holding ponds could have caused the release of sediments from the ponds and whether there was any contamination in that sediment could be answered by the upcoming release of the CDPHE’s creek monitoring results.

Surouchak says that while it’s certainly possible that plutonium in the pond sediments could have been released by floodwaters, he doesn’t believe that it is of much concern because the levels of plutonium in the sediment have been tested and are near or even below background levels. But the ponds are not the most likely area to have released plutonium into the watershed.

The easiest pathway for plutonium to have left the Rocky Flats site during the flood was simply by way of surface soils being washed away by the incredible amounts of rain that fell over the five-day period. That’s because, according to a recent test, plutonium levels on top of and in some of the soils at the Flats are just as prevalent today as they were decades ago.

In 2012, the Rocky Mountain Peace and Justice Center, which has been monitoring the operation and cleanup at Rocky Flats for the past 30 years (see related story, page 15), commissioned a study to determine how much plutonium was still in the soil at the site.

Because they were not allowed to sample on the site itself, the samples were actually taken outside of the fence line on the east side of the Flats, along Indiana Avenue. According to RMPJ, the plutonium levels were just as high in 2012 as they were 40 years earlier, before Rocky Flats had ever been cleaned up.

If true, this would mean that nearly all of the water leaving Rocky Flats during the flood was quite possibly contaminated with small quantities of plutonium.

Surouchak disputes the claims of the 2012 RMPJ study, saying that it was done with an optical rather than radiological analysis and was therefore inapropriate for determining the true levels of plutonium in surface soil.

He does say that the rains left “two inches of sheet water just flowing across the prairie” during the floods.

But when it comes to measuring any contaminant in moving water, the more water that’s flowing, the more diluted the contamination becomes, and the less likely it is to be measured as it passes by a monitor. For that reason, it is quite likely that the CDPHE monitoring stations along the creeks, which saw unprecedented water flows, will find no increase in contamination at the time of the flood, even if the amount of contamination leaving the site had actually increased during the flood.

In fact, it’s quite possible that even the lone monitoring station that, for some still unexplained reason, frequently shows spikes in both plutonium and Americium levels in surface water may well show a decrease in contaminant levels during the flood event itself.

Because of the obvious, temporary dilution from flood waters, the time for accurate testing to determine if contamination was released is actually now, after the flood, under more normal conditions. If plutonium was being transported in floodwaters, the evidence of such movement could likely be found today in the area’s creek and lake sediments or even the drainage ditches along Indiana Avenue.

Surouchack says the DOE has no plans for any additional testing because the levels since the completion of the Cleanup have been so low.

Uranium is another issue at Rocky Flats. While plutonium is heavy and not likely to travel far in groundwater, uranium is the opposite. Uranium is quite soluble and is already contaminating groundwater at Rocky Flats, groundwater that has to be captured and cleaned by way of an expensive, ongoing remediation process.

There is no question that the long, lingering rains of September and the subsequent floods have caused a flushing of sorts in our groundwater aquifers. For that reason it is imperative that the groundwater uranium capture system at Rocky Flats should be rechecked to determine that groundwater pathways weren’t temporarily shifted during the rains and floods, allowing contaminants to bypass the system.

And finally, any massive infiltration of rain such as what occurred in September has the potential to drive old contamination to groundwater, whether it is by getting under caps/covers over pits and landfills or simply by leaching through long-ago-contaminated soil on its way to the underlying aquifer.

Considering that such groundwater normally only moves towards its eventual connection to surface water at a rate of a few feet per year at Rocky Flats, according to the CDPHE, some contamination resulting from September’s rains and floods may not show up in the groundwater and surface water monitoring systems at the site for quite some time.

What happened at Rocky Flats has been called a 1,000-year event. So it’s not likely that we will know or understand all of the implications of such an event for quite some time.

Respond: letters@boulderweekly.com

Plutonium Hitches a Ride on Subsurface Particles

This article, by Arnie Heller, published in Science & Technology Review (October-November. 2011)  , tells of the research led by Annie Kersting of the DOE Livermore National Lab on migration of plutonium attached to colloids in subsurface water.  She says plutonium “travels underground faster and farther than anyone at first expected.” Her  work is of great significance for Rocky Flats, where an unknown quantity of plutonium was knowingly left in the soil on the site after the Superfund cleanup. The cleanup was based on the assumption drawn from computer modeling that plutonium remaining in the Rocky Flats soil would not migrate. Kersting’s work counters this assumption.

Livermore scientists are conducting field studies and microscopic experiments to determine how plutonium is transported in groundwater. Transmission electron microsope images such as the one shown above allowed the researchers to examine colloids taken from groundwater at the Nevada National Security Site (in the background). These studies and others have confirmed that colloids play an important role in transporting plutonium at contaminated sites worldwide.

FOR decades Lawrence Livermore researchers have worked to obtain a detailed understanding of the actinides, a group of 14 radioactive elements that includes plutonium and uranium. The long-standing research is driven by the Laboratory’s historic roles in assessing the nation’s nuclear stockpile, ensuring the safe storage of nuclear waste, and evaluating the fate and transport of radionuclides in the environment.

Environmental contamination by radionuclides, particularly actinides, is a serious concern at several Department of Energy (DOE) facilities, including the Hanford Site, the Nevada National Security Site (formerly the Nevada Test Site), and the former Rocky Flats Plant, as well as at a number of contaminated sites worldwide. Although concentrations of most of the actinides transported from the original source location are detected at levels below regulatory dose limits, actinides’ long half-lives combined with their high toxicity make them of particular concern.

A five-year experimental effort involving about a dozen Laboratory scientists and their collaborators is examining the geochemical processes that control plutonium’s sometimes baffling behavior in the ground. The researchers’ goal is to gain sufficient understanding of the processes that control plutonium’s behavior so they can more accurately predict long-term transport.

“We want to provide decision makers with the scientific basis to support plans for the remediation and long-term stewardship of legacy sites where plutonium contamination occurred,” says Livermore geochemist Annie Kersting, leader of the plutonium transport effort and director of the Livermore branch of the Glenn T. Seaborg Institute, one of the world’s leading centers for actinide research. Other Livermore researchers include lead scientist Mavrik Zavarin, Susan Carroll, Zurong Dai, Ross Williams, Scott Tumey, Pihong Zhao, Ruth Tinnacher, Patrick Huang, Harris Mason, James Begg, and Ruth Kips. Collaborators include Brian Powell (a former Livermore postdoctoral researcher) from Clemson University in South Carolina and Duane Moser from Desert Research Institute in Nevada. The group’s research is funded by the DOE Office of Science’s Biological and Environmental Research Program.

Plutonium Is a Perplexing Element
Scientists regard plutonium as one of the most complex and perplexing elements in the entire periodic table. For example, its transport in groundwater strongly depends on its oxidation state, and plutonium is one of the few elements that can exist in four unique oxidation states simultaneously. Plutonium has been shown to migrate while associated with small (less than 1 micrometer in diameter) particles, or colloids. It may also migrate while associated with mobile organic matter.

For many years, scientists had assumed that plutonium, because of its low solubility in water and its strong tendency to sorb (adhere) to soil and rocks, does not migrate. However, in 1999, Kersting and colleagues from Lawrence Livermore and Los Alamos national laboratories detected plutonium in groundwater at the Nevada Site. Isotopic signatures showed that it originated from a specific nuclear test conducted years earlier more than 1.4 kilometers away. The team found that the plutonium was associated with colloids in the groundwater. Since 1999, additional studies by this team and fieldwork by other scientists have confirmed that colloids play an important role in transporting plutonium at a number of other contaminated sites around the world.

Past laboratory experiments aimed at understanding how plutonium moves in the subsurface were performed at concentrations higher than those observed in the field. However, the dominant geochemical processes operating at higher concentrations may not be the same as those that occur in nature at much lower concentrations. New analytical tools developed at Livermore are providing an opportunity to conduct experiments at the much lower concentrations measured in nature. The extremely sensitive instruments allow researchers for the first time to mimic environmental conditions. Much of the Livermore team’s focus is on determining how plutonium hitches a ride on colloids. These microscopic colloidal particles are found in all waters and can be composed of organic material, inorganic minerals (for example, clays), or microbes.

Kersting says it is important to capture processes such as colloidal transport of contaminants so that models can accurately estimate how much, how far, and how fast plutonium can travel. “Colloidal transport was originally not considered in most transport models. Now, researchers are trying to understand when colloids are important in transport and when they are not,” she says. Currently, a basic understanding of how plutonium adheres to mineral colloids (and desorbs from them) is lacking. In particular, transport models suggest that the rates of sorption and desorption control colloid-facilitated actinide transport, but the factors affecting reaction rates have not been determined experimentally.

Sensitive Instruments Provide Unique Opportunity
Livermore instruments allow researchers to conduct experiments involving extraordinarily low (but environmentally realistic) levels of plutonium in the femtomolar to attomolar range (10^–15 to 10^–18 moles per liter, with a 10^–18 concentration of plutonium being roughly equivalent to dissolving one grain of salt in 100 Olympic-size swimming pools). Instruments include the accelerator mass spectrometer at the Laboratory’s Center for Accelerator Mass Spectrometry and the newest generation of inductively coupled plasma–mass spectrometers. With these extremely sensitive instruments, researchers can identify where the plutonium is sited on a microscopic colloid, determine how it was deposited on the colloid, and elucidate the geochemical processes controlling its mobility.

Plutonium-containing colloids are being characterized in terms of their inorganic, organic, and microbial associations by using a transmission electron microscope and a nanometer-scale secondary-ion mass spectrometer. The Livermore experiments entail reacting extremely low concentrations of plutonium with different materials such as mineral colloids, organic matter, and microbes, and determining to what extent changing parameters, such as pH and concentration, affect the interaction of plutonium with these substrates.

“The experiments show that each mineral colloid interacts with plutonium in a unique manner,” says Zavarin. For example, one form of plutonium, nanocrystalline plutonium-4–oxygen-7 (Pu₄O₇), readily precipitates on goethite, an iron oxide and a common constituent of soil. The team is examining the surface deposition of(Pu₄O₇ to determine why plutonium molecules bind so tightly to goethite. The research indicates that plutonium surface precipitates become distorted as they are deposited, which apparently strengthens the bond between goethite and plutonium. In contrast, this process does not occur when plutonium interacts with quartz (silica dioxide), one of the many silicates found in soil.

The experimental results are being compared to samples taken from contaminated sites at Nevada, Rocky Flats, Hanford, and Russia’s Mayak nuclear complex. Kersting notes that colloids may not play a major transport role at all sites and that the depositional geology and hydrology affect transport. “We’re slowly filling in the scientific gaps,” she says.

One undetermined factor is how microbes affect plutonium transport. Desert Research Institute scientists have collected microbes at the Nevada Site colocated with plutonium contamination, identified and cultured the microbes, and shipped them to Livermore for studying the interaction between plutonium and microbial communities.

Collaborator Duane Moser from the Desert Research Institute collects groundwater containing plutonium from the Nevada Site.

A scanning electron microscope image shows colloidal particles produced during the reaction of nuclear melt glass in groundwater at the Nevada Site.

Leveraging Research Results
Zavarin notes that other actinides are present at contamination sites, and the team’s research results may also shed light on how these elements are transported. “We want to apply our resources to other actinides such as neptunium, americium, and uranium,” he says. The research is also applicable for European scientists and decision makers who are planning the construction of facilities to store high-level waste from nuclear power plants. Kersting’s team is collaborating with several international scientists in this effort.

An added benefit of the Livermore research is the opportunity for a new generation of actinide scientists to work with plutonium. Several postdoctoral researchers and summer graduate students are contributing to the research, with some participating in the Seaborg Institute’s Nuclear Forensics Summer Internship Program, funded by the Department of Homeland Security. Thanks to the research, the most perplexing element on the periodic table is slowly losing some of its mystery about how it travels underground faster and farther than anyone at first expected.

—Arnie Heller

Key Words: actinide, Glenn T. Seaborg Institute, Hanford Site, Mayak nuclear complex, Nevada National Security Site, Nevada Test Site, nuclear forensics, plutonium, Rocky Flats Plant.

For further information contact Annie Kersting (925) 423-3338 (kersting1@llnl.gov).