Groundwater Annual Status Report for Fiscal Year 1999

Nylander, C. L.; Bitner, K. A.; Henning, Karl-Heinz; Johnson, A. S.; Keating, E. H.; Longmire, Patrick; Newman, Brent D.; Robinson, Brooks; Rogers, David B.; Stone, William J.; Vaniman, D. T.

doi:10.2172/752541

Cited by 3 publications

(7 citation statements)

References 6 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…These stratigraphic factors compounded by the relatively high net infiltration rates in wet canyons likely yield the fastest vadose zone travel times for contaminants from the land surface of the plateau to the regional aquifer. Transport to the regional aquifer beneath wet canyons is predicted to be on the order of decades to hundreds of years (LANL, 2003b; Nylander et al, 2003).…”

Section: Vadose Zone Conceptual Models Of the Pajarito Plateaumentioning

confidence: 99%

Conceptual Models of Vadose Zone Flow and Transport beneath the Pajarito Plateau, Los Alamos, New Mexico

Birdsell

Newman

Broxton

et al. 2005

Vadose Zone Journal

View full text Add to dashboard Cite

field observations. To best develop and test conceptual models, supporting data should be derived using a num-The Pajarito Plateau in northern New Mexico, on which the Los ber of observational techniques and include a variety Alamos National Laboratory is situated, is characterized by a thick of data types. vadose zone overlying the regional aquifer of the western Espanola Basin. In this study, conceptual models of vadose zone flow and Los Alamos National Laboratory (the Laboratory or transport processes are presented and then supported through the LANL; Fig. 1) has performed research and development interpretation of field data, including synthesis with numerical models. in nuclear weapons technologies and other national de-The conceptual models differentiate the rate of percolation by their fense activities for more than 60 yr, beginning with the location and surface hydrologic setting, including wet and dry canyons, Manhattan Project in the 1940s. During this time, Laboand wet, dry, and disturbed mesas. Net infiltration beneath wet canratory operations have been accompanied by both disyons is the highest, with rates on the order of a meter per year posal of and intentional or accidental releases of chemi-(100-1000 mm yr Ϫ1 ). Transport to the regional aquifer beneath the cal contaminants into the environment at a variety of wettest canyons is likely on the order of several years to several sites. Contaminants with possible negative impacts to decades, depending on the thicknesses of the various hydrostratigroundwater include high explosives, radionuclides, chemgraphic layers. Perched water is sometimes found beneath wetter canyons and is associated with near-surface alluvial systems and at ical solvents, and metals. Today, the Laboratory is reintermediate depths along low-permeability interfaces such as buried sponsible for ensuring that none of its past contaminant soils or unfractured regions of basalt flows. Percolation through the releases pose a threat to human health now or in the volcanic tuffs is generally considered to be via matrix-dominated flow, future, and to carry out remediation activities to clean whereas fracture flow may play a key role in contaminant transport up contaminated sites. One of the key potential risks is through densely welded tuffs or basalt units beneath wet canyons.groundwater contamination, possibly affecting drinking Infiltration beneath dry canyons and dry mesas is much slower (10 water quality in municipal or private wells. Contaminants mm yr Ϫ1 or less), yielding transport times to the aquifer of hundreds must travel through a thick vadose zone to reach the to several thousands of years. However, long-term surface disturregional aquifer. Therefore, a well-developed conceptual bances at mesa-top locations may alter infiltration rates such that model describing vadose zone flow and transport beneath at a local scale, the infiltration rates temporarily approach those of wetter canyons.

show abstract

Section: Vadose Zone Conceptual Models Of the Pajarito Plateaumentioning

confidence: 99%

Conceptual Models of Vadose Zone Flow and Transport beneath the Pajarito Plateau, Los Alamos, New Mexico

Birdsell

Newman

Broxton

et al. 2005

Vadose Zone Journal

View full text Add to dashboard Cite

show abstract

“…Keating and others (2003) demonstrated that the elevation above which significant recharge occurs at the basin‐scale is very well constrained (2195 ± 177 m). Using streamflow data from the Pajarito Plateau, Kwicklis (Nylander et al, 2003) calculated that if all streamflow loss becomes recharge on the plateau, this would contribute a maximum of 4 to 10% of the total recharge to the aquifer. A more recent estimate, by Kwicklis et al (2005) using a combination of streamflow data and indirect estimations of streamflow, suggests a higher number, approximately 23% (14% total in streams that flow at least partly within LANL boundaries).…”

Section: Hydrogeologic Settingmentioning

confidence: 99%

“…The basalt flows beneath the plateau include massive, fractured lava units, breccia zones, and interflow zones with significant clay content. Permeability within the Cerros del Rio basalts ranges from 10 −11.2 to 10 −13.8 m 2 (Nylander et al, 2003).…”

Section: Hydrogeologic Settingmentioning

confidence: 99%

Development and Application of Numerical Models to Estimate Fluxes through the Regional Aquifer beneath the Pajarito Plateau

Keating

Robinson

Vesselinov

2005

Vadose Zone Journal

View full text Add to dashboard Cite

primarily agricultural) and decreased baseflow because of groundwater production. For example, in 2002 the Before recent drilling and characterization efforts in the vicinity State of New Mexico was unable to honor interstate of Los Alamos National Laboratory (LANL), conceptual models had been developed for recharge and discharge in the regional aquifer on stream compacts for surface water delivery to Texas and the basis of sparse data. By integrating site-wide data into a numerical incurred substantial penalties. There are also concerns model of the aquifer beneath the plateau we provide new insight into about water quality at the regional scale because of a large-scale aquifer properties and fluxes. This model is useful for variety of contaminants, both nonanthropogenic and anunderstanding hydrologic mechanisms, assessing the magnitudes of thropogenic. Beneath the Pajarito Plateau, there is subdifferent terms in the overall water budget, and, through sampling, for stantial contamination from various LANL sources in interpreting contaminant migration velocities in the overlying vadose shallow groundwaters in some locations (primarily alluzone. Modeling results suggest that the majority of water produced vial aquifers), and it is unclear what the ultimate impact in well fields on the plateau, extracted at rates approaching 70% ofof this contamination will be on the regional aquifer in total annual recharge, is derived from storage. This result is insensitive the future. Some of the LANL-derived contamination to assumptions about the percentage of total recharge that occurs in the near vicinity of water supply wells, because of strong anisotropy has been observed in the regional aquifer at trace conin the aquifer that prevents fast transport of local recharge to deeper centrations much below the EPA drinking water stanunits from which production occurs. Robust estimates of fluxes in the dards. To assess the future water quality and quantity shallow portion of the aquifer immediately down gradient of LANL issues, 21 deep characterization wells have been drilled are important for contaminant transport simulations. Our model calsince 1995, and flow and transport models have been culations show that these fluxes have decreased in the past 50 years developed both at the site-and basin-scale.by approximately 10% because of production in water supply wells. Historical liquid effluent discharges in canyons areTo explore the role of parameter uncertainty in flux prediction, a the most likely sources of this deep groundwater conpredictive analysis method was applied. Results showed that predicted tamination. These contaminants must migrate through flux through older basalts in the aquifer can vary by a factor of three the unsaturated rocks of the vadose zone before reachbecause of uncertainty in aquifer properties and total recharge. We explored the impact of model parameter uncertainty on these results; ing the regional aquifer. Some of the most convenient however, the true uncertainty of our predictions, including the imp...

show abstract

“…The piezometric surface of the regional aquifer ranges in depth from about 20 ft above ground level (artesian water conditions) in portions of lower Los Alamos Canyon near the confluence with Guaje Canyon, to about 750 ft below ground surface along the eastern edge of LANL property near PM-1, to more than 1230 ft below ground surface near the center of the Pajarito Plateau at well PM-5. Water in the regional aquifer generally moves eastward to southeastward beneath the plateau toward the Rio Grande, where at least a portion of the water is discharged into the river through seeps and springs (e.g., Purtymun 1984;Purtymun and Stoker 1988;Purtymun 1995;Nylander et al, 2001). Most of these seeps and springs are located adjacent to the western side of the Rio Grande between Otowi Bridge and Frijoles Canyon above Cochiti reservoir.…”

Section: Brief Description Of the Regional Aquifer And The Los Alamosmentioning

confidence: 99%

“…In this area of the Pajarito Plateau, the deeper units of the regional aquifer may have upward hydraulic gradients (Broxton et al 2001a;Broxton et al 2001b). Additional information about recent water-level data and regional aquifer gradient is reported in the LANL Annual Groundwater Status Report (e.g., Nylander et al 2002).…”

Section: Regional Aquifer Characterization Wellsmentioning

confidence: 99%

Water Supply at Los Alamos 1998-2001

Koch¹,

Rogers²

2003

View full text Add to dashboard Cite

Groundwater Annual Status Report for Fiscal Year 1999

Cited by 3 publications

References 6 publications

Conceptual Models of Vadose Zone Flow and Transport beneath the Pajarito Plateau, Los Alamos, New Mexico

Conceptual Models of Vadose Zone Flow and Transport beneath the Pajarito Plateau, Los Alamos, New Mexico

Development and Application of Numerical Models to Estimate Fluxes through the Regional Aquifer beneath the Pajarito Plateau

Water Supply at Los Alamos 1998-2001

Contact Info

Product

Resources

About