This chapter summarizes the committee’s findings and recommendations developed in Chapters 3, 4, and 5 of this report. Los Alamos National Laboratory’s (LANL’s) current groundwater protection program began under mandate from the New Mexico Environment Department (NMED) in 1998, and it is to be completed by 2015 according a Consent Order issued by NMED. To help ensure a timely and successful completion, the Department of Energy (DOE) requested the National Academies to provide technical advice on certain technical aspects of the program. The committee’s statement of task is given in Sidebar 1.1.

Because the groundwater protection program is at about its midpoint, the committee viewed it as a work in progress, and this report is necessarily a snapshot in time. The committee’s findings are based on information presented by LANL and other stakeholders through about April 2007. The committee’s recommendations are directed toward improving the effectiveness of the program and providing a sound scientific basis for LANL’s future remedial actions and long-term monitoring.

LANL’s groundwater protection program faces substantial technical challenges. There is considerable uncertainty about the contamination sources themselves. The pathways for transport of contaminants from their sources include four different hydrologic regimes: (1) surface streams and runoff, (2) near-surface groundwater in the canyon alluvium, (3) intermediate-perched groundwater in the unsaturated (vadose) zone, and (4) a deep, regional aquifer. Each of these regimes adds considerable uncertainty to the understanding of the overall system. Even with best efforts to understand contaminant sources and pathways, the uncertainty will always be great. Nevertheless, LANL has no other options except to advance its program in the face of uncertainty. Surprises will be inevitable in this learning process.

On the positive side, LANL scientists learned a good deal through the Hydrogeologic Workplan, which was conducted from 1998 to 2005 (LANL, 2005a). While the thickness of the vadose zone and the depth of the regional aquifer, some 1000 feet, make their scientific study difficult, these features are assets for groundwater protection. The substantial relief provided by the canyons that cut through the volcanic sequence provides a good conceptual picture of the site’s geology. The direction of surface and groundwater flow is generally known, even if the identification of the specific pathways is problematic.

Regardless of the difficulties that lie ahead, prudence and the law require that a groundwater monitoring system be established. The recommendations in this report support the proposition that it is technically feasible to monitor the groundwater. The efficacy of the monitoring system will have to be determined based on the analysis of the future data that will be obtained as the system is developed.

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.¹ Geochemistry 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 monitoring data are representative of actual groundwater. The specific need is to understand how contaminant migration caused by

groundwater is affected by geologic or anthropogenic media that are encountered along the groundwater’s flowpath. The committee saw few fundamental, site-specific studies that quantitatively address this need. Conducting such studies in the laboratory is not difficult, but it requires dedicated scientific effort to plan and conduct appropriate tests and to interpret their results.

LANL needs better ways to demonstrate its considerable understanding—and eventually its mastery—of potential threats to the regional aquifer. Specifically this means knowing the site’s inventory of contaminants and where they are.² Most contaminants are evidently still in or near their sources; a sizeable fraction of some have migrated into the vadose zone; and a small fraction are in the regional aquifer. This information needs to be quantified and presented succinctly. The committee judged that mass balance is an appropriate tool for this purpose.³ Mass balances, which LANL has begun developing for a few disposal areas (Birdsell et al., 2006), could be developed for other high-inventory areas and integrated to eventually account for contaminants sitewide. Such accounting for contaminants is the essence of groundwater protection, and it can help foster trust among LANL, its regulators, and public stakeholders.

Uncertainty is inherent in scientific knowledge, and work to address uncertainty leads to improved knowledge. LANL needs to do a better job of describing uncertainties in its groundwater protection program to both scientific and public audiences. This includes describing 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 judged that greater openness about uncertainty—on the parts of LANL and its stakeholders—could improve the quality and transparency of LANL’s groundwater protection program.

Peer review is the standard of science. The committee is not hesitant to take 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, and the additional step of summarizing and publishing key portions, as it did with some information from the Hydrogeologic Workplan (VZJ, 2005), can help authenticate LANL’s groundwater protection program. This is not to discount LANL’s other peer-reviewed publications from the program, but rather to encourage more. Besides peer-reviewed literature, other venues are available for peer review of important work that is not amenable to journal publication.⁴ Demonstrations of sound science through peer review will go a long way toward ensuring the effectiveness of LANL’s groundwater protection program and enhancing confidence among stakeholders.

This section gives the detailed findings and recommendations developed in the main text of this report according to the task statement.

Radioactive or chemically hazardous wastes disposed onsite at LANL constitute the sources of contamination that the committee considered in addressing its statement of task. These sources are the inputs from which contaminants enter the soils, rocks, and water that comprise the hydrogeologic environment beneath the LANL 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.⁵

The committee’s statement of task posed three questions regarding sources:

1. What is the state of the Laboratory’s understanding of the major sources of groundwater contamination originating from Laboratory operations and have technically sound measures to control them been implemented?

1. Have potential sources of non-Laboratory groundwater contamination been identified?

2. Have the potential impacts of this [non-Laboratory] contamination on corrective-action decision making been assessed?

The committee’s short answer to the first question is yes for liquid sources and no for solids. Liquid waste discharges are generally eliminated or controlled. LANL’s data indicate that previous liquid discharges were the sources of contamination currently found in groundwater. However, solid wastes and contaminants deemed by LANL to have less near-term potential to impact groundwater have received much less attention than the liquid sources and are not well understood, especially in terms of source inventories.

The short answer to the second question is a qualified yes. The answer to the third has to be no because LANL is only beginning to determine corrective actions under the Consent Order. This aspect of decision making was not discussed with the committee.

The committee offers the following findings and recommendations to assist LANL in future work to understand and control its contamination sources, with emphasis on longer-term concerns that have not been addressed during the first portion of the groundwater protection program.

Solid wastes, e.g., the 25 material disposal areas (MDAs),and certain contaminants deemed by LANL to be essentially immobile (e.g., Pu) have the potential for impactinggroundwater in the future. MDA AB in Technical Area-49 (TA-49), which contains some 2300 Ci of Pu-239, isan example. The committee received little informationthat would provide assurance that these sources are wellunderstood or well controlled.

Priority for investigating sources is established by the Consent Order. This recommendation emphasizes the need to confirm assumptions that underpin the assignment of lower priority to “immobile” wastes.

There are still large uncertainties in LANL’s estimatesof the inventories of principal contaminant sources andtheir locations. Similarly, analyses are lacking to approximate the current locations of contaminants (which mayhave migrated from these sources) in the various hydrogeological units that constitute the LANL site and surrounding areas.

These analyses, with estimates of data uncertainties, should help LANL account for contaminant sources, releases, radioactive decay, and migration through the hydrogeologic system in a way that is transparent and understandable to all of its stakeholders.

Surface water is an important pathway for transportof contaminants to the groundwater. Stormwater canremobilize contaminants that have been deposited incanyons and transport them downstream. The contaminants can enter the shallow groundwater away from theiroriginal source or be transported offsite.

The geochemistry of contaminant migration has not beenstudied at a level of detail comparable to the site investigations conducted under the Hydrogeologic Workplan.This is a gap in LANL’s current groundwater protectionprogram.

LANL will continue to be an active DOE site with thepotential for release of contaminants from its ongoingoperations. Discharges and releases have been cut substantially at TA-50, the location of the site’s radioactiveliquid waste treatment facility. Yet, its discharges will continue to provide a flow of water that will tend to remobilizecontaminants already deposited in the canyons.

LANL carried out its Hydrogeologic Workplan from 1998 through 2004 to better characterize the site’s hydrogeology and the potential pathways for contaminant transport. The purpose of the characterization program was to develop the scientific basis for a sitewide groundwater monitoring plan.

The committee’s statement of task posed two questions regarding LANL’s current (interim) monitoring program:

1. Does the laboratory’s interim groundwater monitoring plan follow good scientific practices? Is it adequate to provide for the early identification and response to potential environmental impacts from the laboratory?

2. Is the scope of groundwater monitoring at the laboratory sufficient to provide data needed for remediation decision making? If not, what data gaps remain, and how can they be filled?

After reviewing LANL’s Interim Facility-wide Monitoring Plan⁷ the committee answered the two parts of item 1 with a qualified yes and no, respectively. While the Interim Plan generally follows good scientific practices, there are opportunities for improving it. The plan is not adequate to provide early identification of potential contaminant migration with high confidence because LANL’s understanding of pathways for contaminant transport, especially inter-watershed pathways, is not yet adequate to support such confidence. The committee answered item 2 with a qualified no.

Findings and recommendations to assist LANL address remaining gaps in pathway conceptualizations and improve its monitoring plans are as follows:

The current conceptualization of the LANL flow systeminto alluvial, intermediate-perched, and regional components, along with their importance to understandingthe flow system within and below wet canyons, is a majoraccomplishment by LANL scientists. However, thereis a lack of understanding of theinterconnectednessofpathways between basins. While there is a general understanding that perched waters are probably redirectingcontaminants from areas directly below canyons wherethey originally infiltrate, to submesa areas and to othernearby canyons, the detailed knowledge needed to predictsubsurface flowpaths does not exist. Lack of understanding of these phenomena, coupled with rapid flow in thealluvium and apparent rapid flow facilitated by perchedwaters, was central to the surprise over detection ofchromium near the water supply wells. An improvedknowledge of these inter-watershed processes is needed todesign an effective, early warning monitoring program.

• Design additional characterization, modeling, andgeochemical investigations to better understandpotential fast pathways between watersheds.

• Increase the area of the regional aquifer that ismonitored by sampling inter-canyon areas frommesas or using directional wells from canyonbottoms.

• Provide additional monitoring locations in thesouthern area of the site and on Pueblo de SanIldefonso lands.

• Develop more applications of geophysical techniques to supplement information provided by welldrilling and sampling, especially for understanding vadose zone pathways.

• As LANL’s site characterization and monitoringprograms mature, well locations should be derivedfrom a quantitative spatial analysis of monitoringwell locations to identify areas with the greatestuncertainty in plume concentrations, using geostatistics or other methods, possibly coupled withflow and transport modeling.

Mathematical models are essential tools for both codifying current knowledge and identifying knowledge gaps.Although LANL is using a numerically sophisticatedmultiphase model for vadose and regional groundwatermodeling, it is not yet possible to predict with confidencewhen, where, or if a contaminant might appear in theregional aquifer. This is due largely to an exceptionallycomplex vadose zone. Studies show that most of the massof many contaminants is likely still in the vadose zone onthe way down from the release location to the regionalaquifer.

• Mathematical models that incorporate the uncertainties from alternative conceptual models shouldunderpin plans for design and operation of thesitewide monitoring system. Characterization ofthe vadose zone begun under the HydrogeologicWorkplan should continue with emphasis on newresults from characterization and monitoringbeing used to test and improve the mathematicalmodels.

• To support an evaluation of the effectiveness ofthe monitoring system to provide early warning ofpotential impacts on the regional aquifer, LANLshould quantify, to the extent possible, the inventory and current location of the contaminantsdisposed of in the major waste sites.

Large waste disposal sites in the dry canyons and on drymesas have not received as much attention as wet canyonsand wet mesas because they presumably lack an aqueousdriver to move contamination. The presumed dry locations have received minimal characterization with regardto the presence, strength, and potential impact of aqueousdrivers. In some of these, surface disturbances have led tounexpected increased infiltration rates. LANL providedfew data to justify assumptions about the relative immobility of wastes at these sites.

LANL’s present conceptualizations of the regional aquifer lead to very different pictures of how contaminantsin the aquifer might behave. If there is low connectivitybetween layers within the aquifer, the contaminantsmight remain near the top of the regional aquifer andmost likely discharge in the springs near the Rio Grande.On the other hand, higher connectivity could result inthe contaminants spreading vertically and more likelyentering the deep screened intervals of regional watersupply wells.

LANL’s efforts to understand the role of geochemistry incontaminant migration have not kept pace with effortsto understand hydrology. The committee found a lack ofbasic, site-specific geochemical data to support LANL’sassumptions about the relative immobility of importantcontaminants—especially radionuclides—along transport pathways and judged that LANL underestimatedthe value of both field and laboratory geochemicalmeasurements.

The following finding and recommendations reflect the committee’s evaluation of the Interim Facility-wide Groundwater Monitoring Plan (LANL 2006c), which was requested in the Statement of Task.

The Hydrogeologic Workplan has been effective inimproving characterization of the site’s hydrogeology.However, the knowledge gained through the workplandoes not appear to have been used effectively in the development of the interim monitoring plan. The workplan ismentioned only in the introduction of the interim plan,and rationale for the siting of new wells in the interimplan is not grounded in the scientific understanding ofthe site evident in the Synthesis Report and other publications such as theVadose Zone Journal(VZJ, 2005).

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?

During this study the committee was presented a good deal of information suggesting that most or all 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 knowledge that could help ensure future success. Evidence about the conditions prevalent around the screens in the compromised wells is indirect—relying on plausible but unproven⁸ chemical interactions, general literature data, analyses of surrogates, and apparent trends in sampling data that may not be statistically valid.

The committee’s statement of task posed two questions regarding the reliability of data produced in LANL’s current monitoring program:

1. Is the laboratory following established scientific practices in assessing the quality of its groundwater monitoring data?

2. Are the data (including qualifiers that describe data precision, accuracy, detection limits, and other items that aid correct interpretation and use of the data) being used appropriately in the laboratory’s remediation decision making?

The short answer to the first item is a qualified yes. 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. Well drilling and completion methods are continuing to evolve, and the site is only beginning to implement its groundwater monitoring program under the Consent Order.

The answer to the second item as written was judged as no. Although LANL appears to be generating sound analytical data, the results presented in databases and LANL reports 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.

The following findings and recommendations are intended to strengthen LANL’s well drilling and sample analyses for site monitoring.

Data from scientifically vetted (peer-reviewed) studies arenecessary to authoritatively address concerns and uncertainties about how drilling and well completion processesmight alter the native conditions around well screensand to ensure reliable monitoring activities in the future.The committee received little scientific information—forexample, on a par with LANL’s publications about vadosezone pathways (VZJ, 2005)—regarding the geochemicalbehavior of contaminants in the subsurface or effects ofnon-native materials (drilling fluids, additives, construction materials) on the geologic media to be sampled.

• Determining the nature of interactions amongmaterials proposed for use in constructing monitoring wells and the types of geological media thatLANL intends to monitor,

• Quantitative measurement of sorption of contaminants onto the natural, added, and possiblyaltered constituents that constitute the samplingenvironment of a monitoring well, and

• Publication of results in peer-reviewed literature.

The committee is not recommending open-ended research. Rather, targeted investigations 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 (known from previous site characterization), and drilling fluids, additives, and other materials intended to be used in constructing the monitoring well(s). Screening tests envisioned by the committee would include simple batch equilibrium tests to measure solubilities and sorption coefficients (K_d) and to determine what, if any, interactions actually occur among drilling materials and the geologic media—and whether alterations are permanent or temporary. More detailed column tests can simulate and measure effects of flow rate and surface area (mass transfer) around the well screens. Planning, conducting, and interpreting the results will require the high quality of science one would expect of a national laboratory.

LANL’s work under the Hydrogeologic Workplan significantly enhanced understanding of the hydrologicalcharacteristics of the site, and lessons learned duringthe program can improve future drilling efforts. Wellsconstructed under the Hydrogeologic Workplan wereintended for characterization. LANL later attempted touse the characterization wells that reached the regionalaquifer for monitoring. As noted earlier, their use formonitoring was evidently compromised by drilling andwell development procedures.

With the more complete hydrogeologic characterizationthat is now available (seeChapter 4), LANL can designand construct future monitoring wells more confidently.LANL’s plans to obtain geologic and geophysical logs during drilling further increase confidence that well screenscan be installed to intercept a contaminant pathway.

• Aborehole drilled through the monitoring zonewithout the introduction of drilling muds or additives (i.e., use air or water),

• One screened interval that targets a single saturated zone, and

• Acarefully planned design (length and depth) ofthe well screen, which is confirmed with information collected in the drilling process.

Drilling under specific conditions and sampling requirements can lead to exceptions to the above, and adapting to circumstances will be necessary.

With regard to LANL’s practices in assessing the qualityof its groundwater sampling data, the committee foundthat good data quality procedures are in place, but thereis a lack of follow-through in how the data are reported.

• having clear data quality objectives;

• documenting how samples are to be collected;

• documenting how data are handled, statisticallycompiled, and reported;

• clear documentation of the quality of the data;and

• identification of all suspect data.

Interpreting data at or near analytical detection limits isan area of growing scientific interest. LANL can benefitfrom scientific exchanges with other groups and organizations that are actively working in this area (e.g., theEnvironmental Protection Agency, American Societyfor Testing and Materials). Lack of agreement betweenLANL, regulators, and concerned citizens as to whatconstitutes the appropriate representation of groundwater contamination data is a source of confusion anddistrust.

LANL’s Groundwater Background Investigation Report(LANL, 2006b) is an important step in establishing levelsof naturally occurring contamination in the regionalaquifer, although some data quality gaps were identifiedby the committee. The Integrated Groundwater Monitoring Plan (LANL, 2006c) lists non-LANL sources ofgroundwater contamination. Such data are important tosupport future remediation decision making.

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.