Hydraulic-property estimates for use with a transient ground-water flow model of the Death Valley regional ground-water flow system, Nevada and California

Belcher, Wayne R.; Elliott, Peggy E.; Geldon, Arthur L.

doi:10.2172/790848

Cited by 25 publications

(32 citation statements)

References 34 publications

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“…Hydraulic properties are assigned on the basis of HGUs using the hydrogeologic-unit flow (HUF2) package (Anderman and Hill, 2000). Values of hydraulic conductivity, storage coefficient, vertical anisotropy, and depth decay of hydraulic conductivity (KDEP package) for the HGUs are based on Belcher et al (2001) and vary spatially by zonation within HGUs based primarily on spatial distribution of geologic properties (Belcher, 2004). Hydrogeologic units in all layers (except the top layer) were assigned values of storage coefficient as obtained from literature sources and were not adjusted during calibration (values estimated during calibration testing were all unrealistically high).…”

Section: Overview Of Regional Groundwater Flow Modelmentioning

confidence: 99%

Uncertainty and Sensitivity of Contaminant Travel Times from the Upgradient Nevada Test Site to the Yucca Mountain Area

Zhu¹,

Pohlmann²,

Chapman³

et al. 2009

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Yucca Mountain (YM), Nevada, has been proposed by the U.S. Department of Energy as the nation's first permanent geologic repository for spent nuclear fuel and highlevel radioactive waste. In this study, the potential for groundwater advective pathways from underground nuclear testing areas on the Nevada Test Site (NTS) to intercept the subsurface of the proposed land withdrawal area for the repository is investigated. The timeframe for advective travel and its uncertainty for possible radionuclide movement along these flow pathways is estimated as a result of effective-porosity value uncertainty for the hydrogeologic units (HGUs) along the flow paths. Furthermore, sensitivity analysis is conducted to determine the most influential HGUs on the advective radionuclide travel times from the NTS to the YM area. Groundwater pathways are obtained using the particle tracking package MODPATH and flow results from the Death Valley regional groundwater flow system (DVRFS) model developed by the U.S. Geological Survey (USGS). Effectiveporosity values for HGUs along these pathways are one of several parameters that determine possible radionuclide travel times between the NTS and proposed YM withdrawal areas. Values and uncertainties of HGU porosities are quantified through evaluation of existing site effective-porosity data and expert professional judgment and are incorporated in the model through Monte Carlo simulations to estimate mean travel times and uncertainties. The simulations are based on two steady-state flow scenarios, the pre-pumping (the initial stress period of the DVRFS model), and the 1998 pumping (assuming steady-state conditions resulting from pumping in the last stress period of the DVRFS model) scenarios for the purpose of long-term prediction and monitoring. The pumping scenario accounts for groundwater withdrawal activities in the Amargosa Desert and other areas downgradient of YM. Considering each detonation in a clustered region around Pahute Mesa (in the NTS operational areas 18, 19, 20, and 30) under the water table as a particle, those particles from the saturated zone detonations were tracked forward using MODPATH to identify hydraulically downgradient groundwater discharge zones and to determine the particles from which detonations will intercept the proposed YM withdrawal area. Out of the 71 detonations in the saturated zone, the flowpaths from 23 of the 71 detonations will intercept the proposed YM withdrawal area under the pre-pumping scenario. For the 1998 pumping scenario, the flowpaths from 55 of the 71 detonations will intercept the proposed YM withdrawal area. Three different effective-porosity data sets compiled in support of regional models of groundwater flow and contaminant transport developed for the NTS and the proposed YM repository are used. The results illustrate that mean minimum travel time from underground nuclear testing areas on the NTS to the proposed YM repository area can vary from just over 700 to nearly 700,000 years, depending on the locations of the undergroun...

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Section: Overview Of Regional Groundwater Flow Modelmentioning

confidence: 99%

Uncertainty and Sensitivity of Contaminant Travel Times from the Upgradient Nevada Test Site to the Yucca Mountain Area

Zhu¹,

Pohlmann²,

Chapman³

et al. 2009

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“…Belcher and Elliot (2001) compiled estimates of transmissivity, hydraulic conductivity, storage coefficients, and anisotropy ratios for major hydrogeologic units within the Death Valley region. Rock permeability has been determined by single and crosshole hydraulic testing (BSC, 2003;Eddebbarh et al, 2003).…”

Section: Regional and Site-specific Groundwater Systemmentioning

confidence: 99%

Feature Detection, Characterization and Confirmation Methodology: Final Report

Karasaki¹,

Apps²,

Doughty³

et al. 2007

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Executive SummaryThis is the final report of the NUMO-LBNL collaborative project: Feature Detection, Characterization and Confirmation Methodology under NUMO-DOE/LBNL collaboration agreement, the task description of which can be found in the Appendix.We examine site characterization projects from several sites in the world. The list includes Yucca Mountain in the USA, Tono and Horonobe in Japan, AECL in Canada, sites in Sweden, and Olkiluoto in Finland. We identify important geologic features and parameters common to most (or all) sites to provide useful information for future repository siting activity. At first glance, one could question whether there was any commonality among the sites, which are in different rock types at different locations. For example, the planned Yucca Mountain site is a dry repository in unsaturated tuff, whereas the Swedish sites are situated in saturated granite. However, the study concludes that indeed there are a number of important common features and parameters among all the sites-namely, (1) fault properties, (2) fracture-matrix interaction (3) groundwater flux, (4) boundary conditions, and (5) the permeability and porosity of the materials.We list the lessons learned from the Yucca Mountain Project and other site characterization programs. Most programs have by and large been quite successful. Nonetheless, there are definitely "should-haves" and "could-haves," or lessons to be learned, in all these programs. Although each site characterization program has some unique aspects, we believe that these crosscutting lessons can be very useful for future site investigations to be conducted in Japan. One of the most common lessons learned is that a repository program should allow for flexibility, in both schedule and approach.We examine field investigation technologies used to collect site characterization data in the field. An extensive list of existing field technologies is presented, with some discussion on usage and limitations. Many of the technologies on the list were in fact used during the characterization of Yucca Mountain and elsewhere by LBNL personnel. The study also includes emerging technologies and identifies the need to develop better estimation of important parameters for repository siting. Notable emerging technologies include 3-D seismic and satellite-based remote sensing and wireless micro electro mechanical systems (MEMS) sensors. They enable cost-effective and ubiquitous monitoring to be applied for site characterization.We list and classify the types of uncertainties involved in site characterization. Uncertainties can exist in all aspects of site characterization: data, interpretation, conceptualization, and modeling. We use the Swedish program to exemplify such uncertainties. We also devote a chapter on geochemical issues regarding the interaction between groundwater and natural and engineered barrier materials. A recommendation has been made to take advantage of the recent advancement in geochemical modeling capabilities in natural systems. Although it is not o...

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“…The plots of measured hydraulic conductivities versus depth that are reported in the literature tend to show a relatively large amount of scatter, and thus a large amount of spread about any best-fit line, representing the functional relationship of decreasing permeability or hydraulic conductivity versus increasing depth (e.g., Lavenue et al, 1990;DOE/NV, 1997;Belcher et al, 2001 and. However, utilizing these depth-dependent relationships is a useful approach to assist in parameterizing groundwater flow models because often there are limited data available to characterize the full depth and lateral extent of all HSUs in large regional groundwater flow models.…”

Section: B-17mentioning

confidence: 99%

Phase II Groundwater Flow Model of Corrective Action Unit 98: Frenchman Flat, Nevada Test Site, Nye County, Nevada, Rev. No.: 0

McCord¹

2006

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Hydraulic-property estimates for use with a transient ground-water flow model of the Death Valley regional ground-water flow system, Nevada and California

Cited by 25 publications

References 34 publications

Uncertainty and Sensitivity of Contaminant Travel Times from the Upgradient Nevada Test Site to the Yucca Mountain Area

Uncertainty and Sensitivity of Contaminant Travel Times from the Upgradient Nevada Test Site to the Yucca Mountain Area

Feature Detection, Characterization and Confirmation Methodology: Final Report

Phase II Groundwater Flow Model of Corrective Action Unit 98: Frenchman Flat, Nevada Test Site, Nye County, Nevada, Rev. No.: 0

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