Plans and Practices for Groundwater Protection at the Los Alamos National Laboratory: Final Report (2007)

The world’s first nuclear bomb was developed in 1943 at a site near the town of Los Alamos, New Mexico. Designated as the Los Alamos National Laboratory (LANL) in 1981, the 40-square-mile site is today operated by Los Alamos National Security LLC¹ under contract to the National Nuclear Security Administration (NNSA) of the U.S. Department of Energy (DOE). Like other sites in the nation’s nuclear weapons complex, the LANL site harbors a legacy of radioactive waste and environmental contamination. Radioactive materials and chemical contaminants have been detected in some portions of the groundwater beneath the site.

Groundwater protection is an important issue because water resources in the LANL area of north-central New Mexico are limited. Seven of Los Alamos County’s twelve drinking water supply wells are located on the LANL site. Los Alamos County and the County and City of Santa Fe have water supply wells located along the projected flowpath of groundwater leaving the LANL site. The Pueblo de San Ildefonso² also lies on the pathways of the groundwater and the few surface streams that flow from the site to the Rio Grande, which supplies water to much of the state.

Under authority of the U.S. Environmental Protection Agency, the State of New Mexico regulates protection of its water resources through the New Mexico Environment Department (NMED). In 1995 NMED found LANL’s groundwater monitoring program to be inadequate. Consequently LANL conducted a detailed workplan to characterize the site’s hydrogeology in order to develop an effective monitoring program. A legally binding Consent Order³ issued by NMED in 2005 establishes requirements and schedules for the monitoring program, which LANL is now developing, as well as a schedule for completing future remedial actions by 2015.

The study described in this report was initially requested by NNSA, which turned to the National Academies for technical advice and recommendations regarding several aspects of LANL’s groundwater protection program. The DOE Office of Environmental Management funded the study. The study came approximately at the juncture between completion of LANL’s hydrogeologic workplan⁴ and initial development of a sitewide monitoring plan. In addressing its statement of task (given in Sidebar 1.1), the committee considered LANL’s groundwater protection program to be work in progress. The committee’s findings are necessarily a snapshot in time, reflecting publicly available information through about April 2007.

Successful completion of the groundwater protection program will not be easy. The program is challenged by scientific and technical problems in understanding and quantifying LANL’s sources of contamination and the migration of contaminants from these sources. Because groundwater is an important resource in the area, citizens are concerned about the dangers of its pollution by LANL. Some citizens’ groups seek assurances of essentially zero contamination. Reflecting citizens’ concerns, state officials and regulators have imposed strict schedules and detailed regulations (e.g., the Consent Order) on the program.

Regardless of the difficulties that lie ahead, prudence and the law require that a groundwater monitoring system be established. In deliberating on the issues in its task statement, the committee came to the conclusion that it is technically feasible for LANL to establish a monitoring system that meets the groundwater protection requirements of the Consent Order. The findings and recommendations presented in this report are intended to help ensure the efficacy of LANL’s work.

There are four overarching findings that arose from the committee’s study and that have relevance to essentially all parts of the task statement.

LANL demonstrated substantial progress in site characterization under the hydrogeologic workplan. However, LANL’s work in geochemistry has not kept pace with work in hydrogeology. Geochemistry⁵ is central to understanding the extent to which contaminants move with groundwater; it is a tool for better understanding hydrogeologic pathways; and it is essential for determining the degree to which groundwater monitoring samples are representative of actual groundwater.

LANL needs better ways to demonstrate its considerable understanding—and eventually its mastery—of potential threats to the regional aquifer arising from site contamination. Specifically this means knowing the site’s inventory of contaminants and where they are. Most contaminants are evidently still in or near their sources; a sizeable fraction of some have migrated into the vadose zone;⁶ and a small fraction are in the regional aquifer. This information can be quantified and presented succinctly by the method referred to as mass balance, which is introduced in Chapter 3.

LANL’s groundwater protection program is proceeding in the face of substantial technical uncertainty—about the contamination sources themselves, pathways by which contaminants might reach potable water, and how contaminants can reliably be detected at near-background levels. Uncertainty is inherent in scientific knowledge, and work to address uncertainty can improve knowledge. LANL needs to do a better job of describing the uncertainties in its groundwater protection program to both scientific and public audiences. This includes fundamental conceptual uncertainty—things that are simply not known, such as the nature of some groundwater pathways—and measurement uncertainty, such as the variability of laboratory results for contaminants detected at very low levels.

The committee was not hesitant to accept LANL’s motto: “The World’s Greatest Science Protecting America” at face value. However, like many publications from DOE laboratories, LANL reports typically fall in the area of non-peer-reviewed literature. LANL has produced massive amounts of report material in its groundwater investigations. The additional step of summarizing and publishing key portions as authoritative contributions to peer-reviewed scientific journals, as done with some information from the hydrogeologic workplan (VZJ, 2005), can demonstrate the scientific merit of the program. This in turn can help allay public concerns about LANL’s ability to protect their groundwater.

The task statement and the outline of this report generally follow the sequence of issues one would consider in developing a groundwater protection program. The first set of questions to be addressed asked the committee to judge LANL’s understanding of its major sources of groundwater contamination and whether these sources have been controlled. The second set asked the committee to judge the scientific basis and scope of LANL’s current (interim) groundwater monitoring program and, in particular, if it is adequate to provide early warning and response to potential groundwater contamination from LANL operations. The third set dealt with practicalities of conducting a monitoring program, including whether LANL is using sound scientific practices in assessing the quality of its groundwater monitoring data and if the data are properly qualified so that they can be interpreted correctly.

In several instances, the committee’s short answers to these questions were negative. Such findings do not necessarily indicate major deficiencies in LANL’s groundwater protection program, but rather that the program is incomplete. Work remains to be done in order to satisfy completely the conditions questioned in the task statement. The committee’s recommendations are intended to help LANL increase its effectiveness in completing its groundwater protection program. Chapter 6 of this report provides a complete summary of all of the committee’s findings and recommendations, which are developed and described in detail in Chapters 3, 4, and 5.

Radioactive or chemically hazardous wastes disposed of onsite at LANL are the sources from which contaminants enter the soils, rocks, and water that comprise the hydrogeologic environment beneath the site. The Laboratory has practiced onsite disposal of its wastes since the early 1940s. Disposal methods include the discharge of liquid effluents into canyons and the emplacement of solid wastes, mainly on mesa tops.⁷

In responding to its task statement, the committee found that liquid waste discharges, which LANL considers to be sources of the contamination currently detected in groundwater, are generally eliminated or controlled. Solid wastes and contaminants deemed by LANL to have less near-term potential to impact groundwater have received much less attention—the committee found that they are not well inventoried or controlled.

These and other findings and recommendations related to sources and their control are described in Chapter 3.

LANL carried out its hydrogeologic workplan from 1998 through 2004 to better characterize the site’s hydrogeology and potential pathways for contaminant transport in order to develop the basis for a sitewide groundwater monitoring plan. The committee found that the hydrogeologic workplan was effective in improving characterization of the site’s hydrogeology.

The task statement directed the committee to review LANL’s current (interim) monitoring plan. In doing so, the committee found that the knowledge gained through the hydrogeologic workplan does not appear to have been used effectively in the development of the interim monitoring plan (LANL, 2006a,c). The workplan is mentioned only in the introduction of the monitoring plan, and rationale for the siting of new wells in the monitoring plan is not grounded in the scientific understanding of the site evident in the Synthesis Report (LANL, 2005a), which summarized results from the workplan.

The committee found that LANL’s current conceptualization of the site’s groundwater system into alluvial, intermediate-perched, and regional components, along with the importance of these components for understanding the flow system within and below wet canyons, is a major accomplishment. However, there is a lack of understanding of the interconnectedness of subsurface pathways between watersheds. While there is a general understanding that perched waters are probably redirecting contaminants from areas directly below canyons where they originally infiltrate to submesa areas and to other nearby canyons, the detailed knowledge needed to predict subsurface flowpaths does not exist.

• Design additional characterization, modeling, and geochemical investigations to better understand potential fast pathways between watersheds.

• Increase the area of the regional aquifer that is monitored by drilling more wells to sample the intercanyon areas underneath the mesas as well as more wells in the canyons.

• Provide additional monitoring locations in the southern area of the site and on Pueblo de San Ildefonso lands.

These and other findings and recommendations related to contaminant pathways and LANL’s current plan for monitoring are described in Chapter 4.

Implementing a monitoring plan involves the practicalities of constructing groundwater wells and analyzing samples from the wells. Any monitoring activity faces a conundrum: If little or no contamination is found, does this mean that there is in fact little or no contamination, or that the monitoring itself is flawed?

In responding to the questions asked in the statement of task, which dealt with data quality issues, the committee found that LANL is using good practices in terms of having the proper quality assurance and quality control (QA/QC) plans and documentation in place, but falls short of consistently carrying out all the procedures cited in the plans. Results of analyzing groundwater samples often do not carry the proper qualifiers according to good QA/QC practices. This especially applies to analytical results near or below the limits of practical quantitation and detection, near the natural background, or both. The difficulty here is that reported detection of contamination that is not statistically significant may be taken as real by regulators and other stakeholders—with concomitant concerns and calls for remedial actions.

During this study the committee was presented with information suggesting that many wells into the regional aquifer at LANL (R-wells) are flawed for the purpose of monitoring. The committee did not disagree, but rather found a lack of basic scientific understanding of the subsurface geochemistry that could help ensure future success. Evidence about the conditions prevalent around the sampling points (screens) in the compromised wells is indirect—relying on plausible but unproven chemical interactions around the screens, general literature data, analyses of surrogates, and apparent trends in sampling data that may not be statistically valid.

The committee received little scientific information—for example, on a par with LANL’s publications about vadose zone pathways (VZJ, 2005)—regarding the geochemical behavior of contaminants in the subsurface or effects of non-native materials (drilling fluids, additives, construction materials) on the geologic media to be sampled. Data from scientifically vetted (peer-reviewed) studies are necessary to authoritatively address concerns and uncertainties about how drilling and well completion processes might alter the native conditions around well screens and to ensure reliable monitoring activities in the future.

• Determining the nature of interactions among materials proposed for use in constructing monitoring wells and the types of geological media that LANL intends to monitor;

• Quantitative measurement of sorption or precipitation of contaminants onto the natural, added, and possibly altered constituents that would constitute the sampling environment of a monitoring well; and

• Publication of results in peer-reviewed literature.

The committee is not recommending open-ended research. Rather the work would underpin plans for future monitoring of specific areas of the site: contaminants of greatest concern in the area; geologic media expected to be sampled; and drilling fluids, additives, and other materials intended to be used in constructing the monitoring well(s).

These and other findings and recommendations related to the implementation of groundwater monitoring at LANL are described in Chapter 5.

LANL’s groundwater protection program is at about its temporal midpoint, continuing for another eight years until 2015. The Consent Order establishes an enforceable process and schedule for the program. The committee hopes that the assessments, findings, and recommendations presented in this report will be useful in informing future technical decisions that will be made within the Consent Order process.