Executive Summary

Introduction

Los Alamos National Laboratory (LANL) in northern New Mexico has played an essential role in the nuclear weapons complex and has practiced poor waste disposal techniques in the past, making it a major source of groundwater contamination (DOE, 2001). The contamination has the potential to impact public health and also brings up issues of environmental justice. LANL is on land that is part of a large Sacred Area that has historically been home to Pueblo tribes and whose natural resources are now at risk of major pollution (Clapp & Silver, 2006; Masco, 2006). There are multiple conversations between the Department of Energy (DOE), the New Mexico Environment Department (NMED), and affected stakeholders about how portions of the property should be remediated, two of which concern plutonium contamination in Material Disposal Area C (MDA-C) and a chromium plume in Technical Area 5 (TA-5) (DOE Office of Environmental Management, 2019). Upcoming decisions will be critical to future land-use at these sites.

MDA-C is a 12-acre plot in TA-50, as shown in Figure ES1, that served as a primary toxic waste dump for LANL and contains significant quantities of plutonium waste. The presence of plutonium threatens regional aquifers that provide drinking water to nearby communities through migration (Marty et al., 1997). The DOE will finalize key actions for remediation upon the release of a corrective measures evaluation in early 2021, which is an opportunity for the community to voice input and concerns. Whether or not plutonium from MDA-C is migrating off the site will help them decide to simply cover the area with an impermeable cap or to relocate the radioactive material to a repository where it will be permanently stored (Nuclear Watch New Mexico, 2020).

TA-5 is the location of a subsurface plume of chromium-6, as shown in Figure ES1 (Amigos Bravos & Concerned Citizens for Nuclear Safety, 2006; Los Alamos Study Group, n.d.). The chromium was a consequence of waste disposal practices on top of Sandia Canyon, from where chromium traveled across and percolated underground into the regional aquifer. Chromium threatens the Pueblo de San Ildefonso and has potential to continue migrating through groundwaters, posing widespread exposure risk (Oswald, 2015; Andersen, 2018). The DOE has enacted an interim measure to control the contamination and will propose a final remedy in 2021, which will be subject to public comment and analyzed for approval by the NMED (DOE, 2015; N3B Los Alamos, 2019). Collecting more sampling data to gain an updated picture of the extent and shape of the plume will help them create a viable treatment plan (Chamberlain, 2019).

The overarching goal of our project was to assess the presence and migration of plutonium-239 from MDA-C and chromium-6 from TA-5 using available environmental sampling data to inform ongoing debates about remediation approaches on the property. Our analyses will serve the purpose of supporting our sponsor, Nuclear Watch New Mexico (NukeWatch), in their safety and environmental protection efforts. NukeWatch has long lobbied for remediation at LANL and calls for more transparency in operational activities at the laboratory. The team delivered on our goals for NukeWatch by:

1. Collecting data about plutonium-2239 and chromium-6 contamination in Los Alamos National Laboratory property and surrounding areas available from a publicly accessible database.

2. Assessing migration of plutonium-239 and chromium-6 in soil and waterborne samples over time.

3. Assessing the feasibility and resilience of remedial options for Material Disposal Area C and the chromium plume.

Methods

The data for our project was sourced from Intellus, a publicly-accessible database that contains environmental records from LANL. We collected chromium-6 contamination data from the plume’s origin in TA-3 as well as Technical Areas 5, 60, and 72 and the Pueblo de San Ildefonso. These locations were chosen based on the general flow of groundwater in the region towards the Rio Grande, which is chromium’s likely migration path. For plutonium, we collected data for plutonium-239 as well as its isotopes plutonium-238 and plutonium-240 since they indicate previous presence of plutonium-239. We pulled data from all across the laboratory property and off-site locations near the property, but we largely focused on TA-50 and downstream technical areas, as shown in Figure ES1. There is some data that exists from 1970, but available data depends on when sampling began in certain locations. A major challenge we experienced was the numerous gaps and inconsistencies in the data taken from Intellus, hindering the extent of our independent assessment.

Using this data, we created visual representations of the chromium and plutonium contamination using graphing and mapping functions in Excel. Specifically, we made concentration graphs, groundwater elevation graphs, sample depth graphs, number of samples graphs, and heat maps depicting concentration levels over time at various locations. Our visuals as a result of our independent assessment of Intellus data offer Nukewatch tools and visual aids to be used in future public events regarding remediation of MDA-C and the chromium plume. As a result of our data analysis, we developed the following results and recommendations.

Results and Recommendations

Plutonium

Our first finding about plutonium contamination is that plutonium is detected beyond LANL boundaries. This is concerning since plutonium was disposed of in MDA-C and MDA-G, but nowhere off-site, meaning plutonium could have migrated across the laboratory. To explore this further, we looked into Cochiti Lake, which is located about ten miles south of the laboratory. Any contamination showing up here would be evidence of significant migration.

Figure ES2 reveals a slight upward trend in plutonium concentrations in Cochiti Lake sediment over the past twenty-six years. Concentrations range from background levels of 0.01 picoCuries per gram (pCi/g) to higher than upper levels of 0.1 pCi/g (Agency for Toxic Substances and Disease Registry, 2011). This warrants concern because Cochiti Lake lies near populated regions such as the town of Albuquerque. Therefore, its contamination could pose risk to many people.

The long and consistent testing period at Cochiti Lake allows for more meaningful analysis than what we have experienced while analyzing data on-site. If testing across wells beyond LANL boundaries was conducted in this manner, a more complete picture of contaminant migration off-site would be available, which would aid in the remediation discussion.

Because the technical areas along the transportation pathway were not tested each year, we could not see how plutonium concentrations were changing. Data trends may be misleading and can be attributed to new wells being tested that were never tested before, not the discovery of plutonium that was not there before. In an attempt to assess migration, we removed data points that were sampled only once, a few times over a short window of time, or sampled sporadically with large gaps between samples. However, even when only mapping the data that was sampled over longer spans of time, there still was not consistency.

Figure ES3 shows multiple areas with higher concentrations of plutonium that raise concern for LANL and the surrounding communities. Some of these areas are outside both MDA-C and MDA-G, therefore providing high probability that plutonium migrated from its original source. However, analyzing the data over time does not yield any concrete results in terms of migration trends. To address information gaps as well as our limited findings about the plutonium contamination at LANL, we propose two recommendations:

1. LANL should design and implement more consistent sampling practices across locations to allow identification of trends in contamination data.

2. The DOE and the NMED should consider factors of climate change and future land-use in analyses of proposed remedial options for MDA-C, which will entail asking questions such as:

1. Will decreased percolation of rainwater through soil reduce likelihood of downwards migration, thus mitigating the need for relocation of contaminants?

2. Does increased reliance on the regional aquifers beneath LANL justify the implementation of more thorough remediation that would remove the sources of plutonium?

3. Will degradation overtime of landfill caps and leachate collection systems be accelerated by harsher storms and increased frequency and size of wildfires?

Chromium

In 2017, the DOE conducted treatment tests at regional wells R-28 and R-42 located in the center of the plume where chromium was highly concentrated as an interim measure effort. These tests show that the treatments were successful, providing evidence in support of a final remedy involving in situ treatment via chemical application. Although the data proves its short-term viability, it is unclear if complications will arise in the long-term.

Another interim measure effort that the DOE implemented was an extract-and-inject system at the southern edge of the chromium plume in which contaminated groundwater is pumped to the surface, treated, and re-introduced into the aquifer. Data of chromium levels at the injection wells show concentrations close to zero. Additionally, a graph of chromium levels at the well in Pueblo property shows that concentration levels are below the legal limit of 50 ppb. Our analysis supports the claim that the extract-and-inject system is currently preventing migration of the plume across the border that LANL shares with the Pueblo. However, there are two areas of concern that could become challenges for the extract-and-inject system at the southern edge of the plume:

1. Contamination from the plume center (CRPZ-2) could migrate directly south or southeast in the direction of groundwater flow because chromium levels at this well have been dangerously above the Environmental Protection Agency drinking water standard of 100 ppb since 2018, and there is a recent increase in concentration.

2. There is still probability that contamination could cross into Pueblo property, proving that the extract-and-inject system is unlikely to be effective by itself to control migration in the long-run because chromium levels at extraction wells along the Pueblo border (CrEX-1 and CrEX-2) remain over 100 ppb, and those at regional wells along the border (R-50 and R-61) have recent values nearing 50 ppb.

Two more important findings about the plume shape are that it has slightly expanded to the west and it is starting to break off and form a second contamination oval to the east. The first is evidenced by the chromium levels in a western monitoring well (MCOI-6) that have lingered above 50 ppb since 2010, suggesting that the plume is wider than the DOE believed it to be in 2019 (Submittal of the Completion Report for Conversion of CrIN-6 to CrEX-5, 2019). The second is evidenced by high chromium levels above 200 ppb at relatively new wells in the east (R-70 and CrEX-5) and gradually increasing levels approaching 50 ppb at the southeast edge, suggesting expansion of the right side of the plume. Figure ES4 shows heat maps depicting the intensity of contamination at various sampling locations of the plume in 2017 and 2020. Comparing these images reveals that the plume has drawn back from the southern border and is elongating, suggesting that interim measure efforts at the bottom of the plume might be redirecting contamination east.

Evidently, concentrations at the plume center remain high and some levels at plume borders are increasing. Additionally, without knowing the future impacts of climate change and how groundwater levels could change in the coming decades, mischaracterizing the plume and underestimating chromium migration could pose risk to the widespread community should contamination spread to the Pueblo or Los Alamos water supply wells. Therefore, we propose four recommendations:

1. For LANL to continue the extract-and-inject method of controlling the plume until full-scale remediation is planned and deployed,

2. For the DOE to install new monitoring wells in Pueblo territory along the border with TA-5 to ensure chromium contamination is not continuing to migrate off LANL property,

3. For the DOE to install additional monitoring wells surrounding R-70 that will aid in characterizing the northeast area of the plume, and

4. For LANL to take sample depth and groundwater table data for TA-5 to aid in projection of plume migration over time due to changing water tables in the region.

The Value of Independent Assessments to Improve Transparency

Independent assessments are of high importance for a DOE facility such as LANL. LANL’s own reports regarding findings on contamination data can be susceptible to bias (Tuler & Kasperson, 2013). Independent assessments done by us, watchdog organizations, and any other third-party would reduce this bias and are more reliable to the community. Funding for organizations that do this work will allow for different groups to provide their own assessments, and increase social trust in the laboratory itself (Tuler & Kasperson, 2013). Because of its ability to improve the conditions, we recommend more financial support from the DOE to enable watchdog organizations and others to do independent assessments of environmental data in New Mexico. These funds can promote public interest and involvement with decision-making processes regarding remediation of contaminated sites as well as to promote best practices for remediation of contaminated sites.