Hydrology: Projects

Modeling Yucca-Mountain Saturated-Zone Flow and Transport

Yucca Mountain will serve as the nation's first long-term geologic repository for radioactive waste and spent nuclear fuel. It will use barrier systems to keep the stored waste safely in place. Monitoring the performance of these barrier systems will be critical to ensure public health and safety.

Because the Yucca Mountain system is very complex, existing systems to model and monitor site performance involve uncertainty. We work to reduce this uncertainty and increase confidence that the Site-Scale Saturated-Zone Flow and Transport Model provides accurate information about saturated-zone flow and its role as part of the barrier systems. Our work includes thermal modeling, hydrogeochemical analyses, and the use of new hydrogeological and boundary fluxes data.

Evaluating Disposal Strategies for Radioactive Waste.

What happens after radioactive waste is placed in a waste repository? How can we ensure that the waste stays in place? To answer these questions, we are investigating the risks associated with the transport of radionuclides in groundwater at the Nevada Test Site. We are developing a reactive transport model using results from field observations and facture-column experiments. Our goal is to use our test data and transport model to define the parameters for the physical and chemical processes that affect colloid-facilitated transport of plutonium.

Where's the Water? Modeling the Española Basin Aquifer

he Española basin provides drinking water to an ever-growing population in the high desert of Northern New Mexico. Will it be able to provide safe, sufficient water for decades to come? Or will contaminants and over-pumping destroy the water subply?

To address these questions, we draw on large sets of real-world data to simulate and predict the behavior of the water subply under a range of "what if" scenarios. We integrate hydrologic, geologic, geophysical, and geochemical data through 3-D flow and transport modeling. We also use numerical analysis techniques to understand how reliable our predictions are.

Three-dimensional basin model computational domain showing local topography.

Our major accomplishments include capture zone analysis of areas near the Rio Grande River and estimations of the groundwater flow paths, travel times, and contaminant dilution factors.

Looking at the Lab's Impact: Hydrogeology of the Pajarito Plateau

How have years of Laboratory activity at various sites on the Pajarito Plateau affected the groundwater of Northern New Mexico? To answer this question and maintain compliance with U.S. Environmental Protection Agency standards, we plan and execute a broad spectrum of hydrogeologic investigations across the Pajarito Plateau. We use data from these investigations to develop conceptual models for groundwater systems and to model contaminant transport as part of risk assessments and site decisions.

By collecting data from 32 deep wells in the regional aquifer and 51 shallow wells in canyon-floor alluvium, we refine our understanding of the Laboratory's hydrogeologic framework. Our increased knowledge of recharge areas, flow paths, and flow rates will help us to successfully define areas of potential groundwater contamination and predict the direction and rate at which that contamination will move.

Fig. 2. Data from hydrogeologic investigations are used to develop conceptual models for groundwater systems and to model contaminant transport as part of risk assessments and site decisions. Shown are a pore-water nitrate profile from a drillhole in Mortandad Canyon, and a conceptual model block diagram for highexplosives transport at TA-16.

Confining Radioactive Waste: Assessing Surface and Near-Surface Hydrologic Processes in Canyons at Los Alamos

Radioactive waste poses health and environmental hazards. Confining its spread is critical. But before we can confine it, we must know what causes it to spread.

We evaluate the human health and ecological risks from radioactive and nonradioactive Laboratory-derived contaminants in the canyons surrounding Los Alamos. We assess future impacts of the transport of these contaminants through the canyons to areas outside the Laboratory. Our work includes sediment sampling, geomorphic mapping, and surface-water and alluvial groundwater investigations. Recent progress includes publishing a probabilistic model of the fate of sediment and other pollutants in fluvial systems.