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Title: Development and Testing of a Groundwater Management Model for the Faultless Underground Nuclear Test, Central Nevada Test Area

Abstract

This document describes the development and application of a user-friendly and efficient groundwater management model of the Central Nevada Test Area (CNTA) and surrounding areas that will allow the U.S. Department of Energy and state personnel to evaluate the impact of future proposed scenarios. The management model consists of a simple hydrologic model within an interactive groundwater management framework. This framework is based on an object user interface that was developed by the U.S. Geological Survey and has been used by the Desert Research Institute researchers and others to couple disparate environmental resource models, manage the necessary temporal and spatial data, and evaluate model results for management decision making. This framework was modified and applied to the CNTA and surrounding Hot Creek Valley. The utility of the management model was demonstrated through the application of hypothetical future scenarios including mineral mining, regional expansion of agriculture, geothermal energy production, and export of water to large urban areas outside the region. While the results from some of the scenarios indicated potential impacts to the region near CNTA and others did not, together they demonstrate the usefulness of the management tool for managers who need to evaluate the impact proposed changes in groundwatermore » use in or near CNTA may have on radionuclide migration.« less

Authors:
; ; ; ;
Publication Date:
Research Org.:
Desert Research Institute, Nevada System of Higher Education
Sponsoring Org.:
USDOE
OSTI Identifier:
875339
Report Number(s):
45212; DOE/NV/13609-41
TRN: US200603%%93
DOE Contract Number:
AC52-00NV13609
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
15 GEOTHERMAL ENERGY; AGRICULTURE; DECISION MAKING; EXPORTS; GEOLOGIC SURVEYS; GEOTHERMAL ENERGY; MANAGEMENT; MINING; PERSONNEL; PRODUCTION; RADIONUCLIDE MIGRATION; STREAMS; TESTING; URBAN AREAS; WATER; GROUND WATER; Geothermal Legacy

Citation Formats

Douglas P. Boyle, Gregg Lamorey, Scott Bassett, Greg Pohll, and Jenny Chapman. Development and Testing of a Groundwater Management Model for the Faultless Underground Nuclear Test, Central Nevada Test Area. United States: N. p., 2006. Web. doi:10.2172/875339.
Douglas P. Boyle, Gregg Lamorey, Scott Bassett, Greg Pohll, & Jenny Chapman. Development and Testing of a Groundwater Management Model for the Faultless Underground Nuclear Test, Central Nevada Test Area. United States. doi:10.2172/875339.
Douglas P. Boyle, Gregg Lamorey, Scott Bassett, Greg Pohll, and Jenny Chapman. Wed . "Development and Testing of a Groundwater Management Model for the Faultless Underground Nuclear Test, Central Nevada Test Area". United States. doi:10.2172/875339. https://www.osti.gov/servlets/purl/875339.
@article{osti_875339,
title = {Development and Testing of a Groundwater Management Model for the Faultless Underground Nuclear Test, Central Nevada Test Area},
author = {Douglas P. Boyle and Gregg Lamorey and Scott Bassett and Greg Pohll and Jenny Chapman},
abstractNote = {This document describes the development and application of a user-friendly and efficient groundwater management model of the Central Nevada Test Area (CNTA) and surrounding areas that will allow the U.S. Department of Energy and state personnel to evaluate the impact of future proposed scenarios. The management model consists of a simple hydrologic model within an interactive groundwater management framework. This framework is based on an object user interface that was developed by the U.S. Geological Survey and has been used by the Desert Research Institute researchers and others to couple disparate environmental resource models, manage the necessary temporal and spatial data, and evaluate model results for management decision making. This framework was modified and applied to the CNTA and surrounding Hot Creek Valley. The utility of the management model was demonstrated through the application of hypothetical future scenarios including mineral mining, regional expansion of agriculture, geothermal energy production, and export of water to large urban areas outside the region. While the results from some of the scenarios indicated potential impacts to the region near CNTA and others did not, together they demonstrate the usefulness of the management tool for managers who need to evaluate the impact proposed changes in groundwater use in or near CNTA may have on radionuclide migration.},
doi = {10.2172/875339},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Wed Jan 25 00:00:00 EST 2006},
month = {Wed Jan 25 00:00:00 EST 2006}
}

Technical Report:

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  • Many sites of groundwater contamination rely heavily on complex numerical models of flow and transport to develop closure plans. This has created a need for tools and approaches that can be used to build confidence in model predictions and make it apparent to regulators, policy makers, and the public that these models are sufficient for decision making. This confidence building is a long-term iterative process and it is this process that should be termed ''model validation.'' Model validation is a process not an end result. That is, the process of model validation cannot always assure acceptable prediction or quality ofmore » the model. Rather, it provides safeguard against faulty models or inadequately developed and tested models. Therefore, development of a systematic approach for evaluating and validating subsurface predictive models and guiding field activities for data collection and long-term monitoring is strongly needed. This report presents a review of model validation studies that pertain to groundwater flow and transport modeling. Definitions, literature debates, previously proposed validation strategies, and conferences and symposia that focused on subsurface model validation are reviewed and discussed. The review is general in nature, but the focus of the discussion is on site-specific, predictive groundwater models that are used for making decisions regarding remediation activities and site closure. An attempt is made to compile most of the published studies on groundwater model validation and assemble what has been proposed or used for validating subsurface models. The aim is to provide a reasonable starting point to aid the development of the validation plan for the groundwater flow and transport model of the Faultless nuclear test conducted at the Central Nevada Test Area (CNTA). The review of previous studies on model validation shows that there does not exist a set of specific procedures and tests that can be easily adapted and applied to determine the validity of site-specific groundwater models. This is true for both deterministic and stochastic models, with the latter posing a more difficult and challenging problem when it comes to validation. This report then proposes a general validation approach for the CNTA model, which addresses some of the important issues recognized in previous validation studies, conferences, and symposia as crucial to the process. The proposed approach links model building, model calibration, model predictions, data collection, model evaluations, and model validation in an iterative loop. The approach focuses on use of collected validation data to reduce model uncertainty and narrow the range of possible outcomes of stochastic numerical models. It accounts for the stochastic nature of the numerical CNTA model, which used Monte Carlo simulation approach. The proposed methodology relies on the premise that absolute validity is not even a theoretical possibility and is not a regulatory requirement. Rather, it highlights the importance of testing as many aspects of the model as possible and using as many diverse statistical tools as possible for rigorous checking and confidence building in the model and its predictions. It is this confidence that will eventually allow for regulator and public acceptance of decisions based on the model predictions.« less
  • An evaluation of groundwater monitoring at non-Nevada Test Site underground nuclear test sites raised questions about the potential for radionuclide migration from the Faultless event and how to best monitor for such migration. With its long standing interest in the Faultless area and background in Nevada hydrogeology, the Desert Research Institute conducted a field investigation in FY92 to address the following issues: The status of chimney infilling (which determines the potential for migration); the best level(s) from which to collect samples from the nearby monitoring wells, HTH-1 and HTH-2; the status of hydraulic heads in the monitoring well area followingmore » records of sustained elevated post-shot heads. The field investigation was conducted from July 27 to 31 and August 4 to 7, 1992. Temperature and electrical conductivity logging were performed in HTH-1, HTH-2, and UC-1-P-2SR. Water samples were collected from HTH-1 and HTH-2. Lawrence Livermore National Laboratory (LLNL) also collected samples during the July trip, including samples from UC-1-P-2SR. This report presents the data gathered during these field excursions and some preliminary conclusions. Full interpretation of the data in light of the issues listed above is planned for FY93.« less
  • The Central Nevada Test Area was the site of the Faultless underground nuclear test that could be a source of radionuclide contamination to aquifers in Hot Creek Valley, Nevada. Field studies in 1992 and 1993 have used hydrologic logging and water sampling to determine the adequacy of the current groundwater monitoring network and the status of water-level recovery to pre-shot levels in the nuclear chimney. The field studies have determined that there is a possibility for contaminant migration away from the Faultless event though the pre-event water level has not been attained, while new data raise questions about the abilitymore » of the current monitoring network to detect migration. Hydrologic logs from the postshot hole (drilled into the chimney created by the nuclear detonation) reveal inflow around 485 m below land surface. The physical and chemical characteristics of the inflow water indicate that its source is much deeper in the chimney, perhaps driven upward in a convection cell generated by heat near the nuclear cavity. Logging and sampling at monitoring wells HTH-1 and HTH-2 revealed that the completion of HTH-1 may be responsible for its elevated water level (as compared to pre-nuclear test levels) and may have also created a local mound in the water table in the alluvium that accounts for higher post-test water levels at HTH-2. This mound would serve to divert flow around the monitoring wells, so that only migration of contaminants through the underlying, higher pressure, volcanic units is currently monitored. A hydraulic high found in an abandoned hole located between the nuclear chimney and the monitoring wells further reduces the likelihood of HTH-1 or HTH-2 intercepting contaminant migration.« less
  • An evaluation of groundwater monitoring at non-Nevada Test Site underground nuclear test sites raised questions about the potential for radionuclide migration from the Faultless event and how to best monitor for such migration. With its long standing interest in the Faultless area and background in Nevada hydrogeology, the Desert Research Institute conducted a field investigation in FY92 to address the following issues: The status of chimney infilling (which determines the potential for migration); the best level(s) from which to collect samples from the nearby monitoring wells, HTH-1 and HTH-2; the status of hydraulic heads in the monitoring well area followingmore » records of sustained elevated post-shot heads. The field investigation was conducted from July 27 to 31 and August 4 to 7, 1992. Temperature and electrical conductivity logging were performed in HTH-1, HTH-2, and UC-1-P-2SR. Water samples were collected from HTH-1 and HTH-2. Lawrence Livermore National Laboratory (LLNL) also collected samples during the July trip, including samples from UC-1-P-2SR. This report presents the data gathered during these field excursions and some preliminary conclusions. Full interpretation of the data in light of the issues listed above is planned for FY93.« less
  • The Central Nevada Test Area (CNTA) is a U.S. Department of Energy (DOE) site undergoing environmental restoration. The CNTA is located about 95 km northeast of Tonopah, Nevada, and 175 km southwest of Ely, Nevada (Figure 1.1). It was the site of the Faultless underground nuclear test conducted by the U.S. Atomic Energy Commission (DOE's predecessor agency) in January 1968. The purposes of this test were to gauge the seismic effects of a relatively large, high-yield detonation completed in Hot Creek Valley (outside the Nevada Test Site [NTS]) and to determine the suitability of the site for future large detonations.more » The yield of the Faultless underground nuclear test was between 200 kilotons and 1 megaton (DOE, 2000). A three-dimensional flow and transport model was created for the CNTA site (Pohlmann et al., 1999) and determined acceptable by DOE and the Nevada Division of Environmental Protection (NDEP) for predicting contaminant boundaries for the site.« less