Hydraulic characterization of volcanic rocks in Pahute Mesa using an integrated analysis of 16 multiple-well aquifer tests, Nevada National Security Site, 2009–14

Abstract

For more information on the USGS-the Federal source for science about the Earth, its natural and living resources, natural hazards, and the environment-visit http://www.usgs.gov or call 1-888-ASK-USGS.For an overview of USGS information products, including maps, imagery, and publications, visit http://store.usgs.gov/.Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government.Although this information product, for the most part, is in the public domain, it also may contain copyrighted materials as noted in the text. Permission to reproduce copyrighted items must be secured from the copyright owner.Suggested citation: Garcia, C.A., Jackson, T.R., Halford, K.J., Sweetkind, D.S., Damar, N.A., Fenelon, J.M., and Reiner, S.R., 2017, Hydraulic characterization of volcanic rocks in Pahute Mesa using an Integrated Analysis of 16 multiple-well aquifer tests, Nevada National Security Site, 2009-14: U.S. Geological Survey Scientific Investigations Report 2016-5151, 62 p., https://doi.org/10.3133/sir20165151. ISSN 2328-0328 (online) iii AcknowledgmentsThis report was made possible by funding from the U.S. Department of Energy under Interagency Agreement DE-NA0001654 with the Department of Energy, National Nuclear Security Administration.The authors gratefully acknowledge the U.S. Department of Energy (DOE), Navarro Nevada Environmental Services, LLC., Navarro-Intera, LLC, and Navarro for providing aquifer test data at pumping wells, long-term water-level monitoring data at observation and background wells, and the draft Phase II hydrostratigraphic framework model; Jeffery Wurtz and Daniel Neubauer of Navarro and Jeffery Sanchez of Navarro-Intera, LLC, for data collection and data processing; and Peter Martian of Navarro and Rishi Parashar of the Desert Research Institute for helpful review comments.The authors also gratefully acknowledge Terry L. Miller, Glenn L. Locke, and Gary L. Otto, retired, for data collection and data processing and Shana L. Mashburn and Marshall W. Gannett, all of the U.S. Geological Survey, for helpful review comments. Horizontal coordinate information is referenced to the North American Datum of 1983 (NAD 83).Elevation, as used in this report, refers to distance above the vertical datum. Supplemental Information AbstractAn improved understanding of groundwater flow and radionuclide migration downgradient from underground nuclear-testing areas at Pahute Mesa, Nevada National Security Site, requires accurate subsurface hydraulic characterization. To improve conceptual models of flow and transport in the complex hydrogeologic system beneath Pahute Mesa, the U.S. Geological Survey characterized bulk hydraulic properties of volcanic rocks using an integrated analysis of 16 multiple-well aquifer tests. Single-well aquifer-test analyses provided transmissivity estimates at pumped wells. Transmissivity estimates ranged from less than 1 to about 100,000 square feet per day in Pahute Mesa and the vicinity. Drawdown from multiple-wel...

Pervasive, Preferential Flow through Mega‐Thick Unsaturated Zones in the Southern Great Basin

“…Focused recharge at the water table, analogous to a slug injection, will propagate outward to distant wells as a hydraulic‐pressure response. Hydraulic responses propagating more than a kilometer have been noted from large‐scale multiple‐well aquifer test investigations on Pahute Mesa (Garcia et al 2017).…”

Understanding long-term groundwater flow at Pahute Mesa and vicinity, Nevada National Security Site, USA, from naturally occurring geochemical and isotopic tracers

“…Welded tuffs and lavas tend to be the most permeable rocks and are designated as aquifers, whereas porous, altered zeolitic rocks are generally the least permeable rocks and are considered confining units. However, individual rock types exhibit considerable internal heterogeneity and substantial overlap with other rock types in both their measured and model-calibrated permeabilities (Fenelon et al 2016;Garcia et al 2017;Frus and Halford 2018;Halford and Jackson 2020). Given that for almost all hydrostratigraphic units (HSUs), the permeability of the rock matrix is very low compared to the bulk-rock permeability, the variability in bulk-rock permeability can be reasonably attributed to spatial variations in the density, openness, and interconnectedness of fractures.…”

“…Fig. 5 Cross sections through the Pahute Mesa Bench area a east-west and b north-south (modified fromGarcia et al 2017) …”