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Title: Processing and geologic analysis of conventional cores from well ER-20-6 No. 1, Nevada Test Site

Abstract

In 1996, Well Cluster ER-20-6 was drilled on Pahute Mesa in Area 20, in the northwestern corner of the Nevada Test Site (NTS). The three wells of the cluster are located from 166 to 296 meters (m) (544 to 971 feet [ft]) southwest of the site of the underground nuclear test code-named BULLION, conducted in 1990 in Emplacement Hole U-20bd. The well cluster was planned to be the site of a forced-gradient experiment designed to investigate radionuclide transport in groundwater. To obtain additional information on the occurrence of radionuclides, nature of fractures, and lithology, a portion of Well ER-20-6 No. 1, the hole closest to the explosion cavity, was cored for later analysis. Bechtel Nevada (BN) geologists originally prepared the geologic interpretation of the Well Cluster ER-20-6 site and documented the geology of each well in the cluster. However, the cores from Well ER-20-6 No. 1 were not accessible at the time of that work. As the forced-gradient experiment and other radio nuclide migration studies associated with the well cluster progressed, it was deemed appropriate to open the cores, describe the geology, and re-package the core for long-term air-tight storage. This report documents and describes the processing, geologic analysis, andmore » preservation of the conventional cores from Well ER20-6 No. 1.« less

Authors:
;  [1]
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  1. and others
Publication Date:
Research Org.:
Bechtel Nevada Corp., Las Vegas, NV (United States)
Sponsoring Org.:
USDOE, Washington, DC (United States)
OSTI Identifier:
623024
Report Number(s):
DOE/NV/11718-162
ON: DE98052966; TRN: 98:006916
DOE Contract Number:
AC08-96NV11718
Resource Type:
Technical Report
Resource Relation:
Other Information: PBD: Sep 1997
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES; 45 MILITARY TECHNOLOGY, WEAPONRY, AND NATIONAL DEFENSE; NEVADA TEST SITE; SITE CHARACTERIZATION; BOREHOLES; GROUND WATER; NUCLEAR EXPLOSIONS; UNDERGROUND EXPLOSIONS; DRILL CORES; RADIONUCLIDE MIGRATION; RADIOECOLOGICAL CONCENTRATION; RADIOISOTOPES

Citation Formats

Prothro, L.B., Townsend, M.J., and Drellack, S.L. Jr.. Processing and geologic analysis of conventional cores from well ER-20-6 No. 1, Nevada Test Site. United States: N. p., 1997. Web. doi:10.2172/623024.
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Prothro, L.B., Townsend, M.J., & Drellack, S.L. Jr.. Processing and geologic analysis of conventional cores from well ER-20-6 No. 1, Nevada Test Site. United States. doi:10.2172/623024.
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Prothro, L.B., Townsend, M.J., and Drellack, S.L. Jr.. Mon . "Processing and geologic analysis of conventional cores from well ER-20-6 No. 1, Nevada Test Site". United States. doi:10.2172/623024. https://www.osti.gov/servlets/purl/623024.
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@article{osti_623024,
title = {Processing and geologic analysis of conventional cores from well ER-20-6 No. 1, Nevada Test Site},
author = {Prothro, L.B., Townsend, M.J. and Drellack, S.L. Jr.},
abstractNote = {In 1996, Well Cluster ER-20-6 was drilled on Pahute Mesa in Area 20, in the northwestern corner of the Nevada Test Site (NTS). The three wells of the cluster are located from 166 to 296 meters (m) (544 to 971 feet [ft]) southwest of the site of the underground nuclear test code-named BULLION, conducted in 1990 in Emplacement Hole U-20bd. The well cluster was planned to be the site of a forced-gradient experiment designed to investigate radionuclide transport in groundwater. To obtain additional information on the occurrence of radionuclides, nature of fractures, and lithology, a portion of Well ER-20-6 No. 1, the hole closest to the explosion cavity, was cored for later analysis. Bechtel Nevada (BN) geologists originally prepared the geologic interpretation of the Well Cluster ER-20-6 site and documented the geology of each well in the cluster. However, the cores from Well ER-20-6 No. 1 were not accessible at the time of that work. As the forced-gradient experiment and other radio nuclide migration studies associated with the well cluster progressed, it was deemed appropriate to open the cores, describe the geology, and re-package the core for long-term air-tight storage. This report documents and describes the processing, geologic analysis, and preservation of the conventional cores from Well ER20-6 No. 1.},
doi = {10.2172/623024},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Mon Sep 01 00:00:00 EDT 1997},
month = {Mon Sep 01 00:00:00 EDT 1997}
}
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Technical Report:
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DOI:  10.2172/623024
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  • This report documents the interpretation and analysis of the hydraulic data collected for the Fiscal Year (FY) 2004 Multiple-Well Aquifer Test-Tracer Test (MWAT-TT) conducted at the ER-6-1 Well Cluster in Yucca Flat Corrective Action Unit (CAU) 97, on the Nevada Test Site (NTS). The MWAT-TT was performed to investigate CAU-scale groundwater flow and transport processes related to the transport of radionuclides from sources on the NTS through the Lower Carbonate Aquifer (LCA) Hydrostratigraphic Unit (HSU). The ER-6-1 MWAT-TT was planned and executed by contractor participants for the Underground Test Area (UGTA) Project of the Environmental Restoration (ER) program of themore » U.S. Department of Energy (DOE), National Nuclear Security Administration Nevada Site Office (NNSA/NSO). Participants included Stoller-Navarro Joint Venture (SNJV), the Environmental Engineering Services Contractor; Bechtel Nevada (BN); the Desert Research Institute (DRI); Los Alamos National Laboratory; and the University of Nevada, Las Vegas-Harry Reid Center. The SNJV team consists of the S.M. Stoller Corporation, Navarro Research and Engineering, Battelle Memorial Institute, INTERA Inc., and Weston Solutions, Inc. The MWAT-TT was implemented according to the ''Underground Test Area Project, ER-6-1 Multi-Well Aquifer Test - Tracer Test Plan'' (SNJV, 2004a) issued in April 2004. The objective of the aquifer test was to determine flow processes and local hydraulic properties for the LCA through long-term constant-rate pumping at the well cluster. This objective was to be achieved in conjunction with detailed sampling of the composite tracer breakthrough at the pumping well, as well as with depth-specific sampling and logging at multiple wells, to provide information for the depth-discrete analysis of formation hydraulic properties, particularly with regard to fracture properties.« less

  • The ER-6-1 multiple-well aquifer test-tracer test (MWAT-TT) investigated groundwater flow and transport processes relevant to the transport of radionuclides from sources on the Nevada Test Site (NTS) through the lower carbonate aquifer (LCA) hydrostratigraphic unit (HSU). The LCA, which is present beneath much of the NTS, is the principal aquifer for much of southern Nevada. This aquifer consists mostly of limestone and dolomite, and is pervasively fractured. Groundwater flow in this aquifer is primarily in the fractures, and the hydraulic properties are primarily related to fracture frequency and fracture characteristics (e.g., mineral coatings, aperture, connectivity). The objective of the multiple-wellmore » aquifer test (MWAT) was to determine flow and hydraulic characteristics for the LCA in Yucca Flat. The data were used to derive representative flow model and parameter values for the LCA. The items of specific interest are: Hydraulic conductivity; Storage parameters; Dual-porosity behavior; and Fracture flow characteristics. The objective of the tracer transport experiment was to evaluate the transport properties and processes of the LCA and to derive representative transport parameter values for the LCA. The properties of specific interest are: Effective porosity; Matrix diffusion; Longitudinal dispersivity; Adsorption characteristics; and Colloid transport characteristics. These properties substantially control the rate of transport of contaminants in the groundwater system and concentration distributions. To best support modeling at the scale of the corrective action unit (CAU), these properties must be investigated at the field scale. The processes represented by these parameters are affected by in-situ factors that are either difficult to investigate at the laboratory scale or operate at a much larger scale than can be reproduced in the laboratory. Measurements at the field scale provide a better understanding of the effective average parameter values. The scale of this tracer test is still small compared to the scale of a CAU, but is of sufficient scale to be generally representative of the processes that affect in-situ transport. The scale of the tracer test undertaken is limited by the rate of transport in the formation and the resultant time frame required for completing such a test. The measurements at the field scale will provide information for relating laboratory measurements for transport processes to the larger scale. This report describes the analysis of the tracer test data and development of a conceptual model of transport in the LCA in Yucca Flat.« less

  • This report documents the analysis of data collected for Well ER-6-2 during fiscal year (FY) 2004 Yucca Flat well development and testing program (herein referred to as the ''testing program''). Participants in Well ER-6-2 field development and hydraulic testing activities were: Stoller-Navarro Joint Venture (SNJV), Bechtel Nevada (BN), Desert Research Institute (DRI), Los Alamos National Laboratory (LANL), Lawrence Livermore National Laboratory (LLNL), U.S. Geological Survey (USGS), and the University of Nevada, Las Vegas-Harry Reid Center (UNLV-HRC). The analyses of data collected from the Well ER-6-2 testing program were performed by the SNJV.

  • ER-20-6{number_sign}1 was cored to determine fracture and lithologic properties proximal to the BULLION test cavity. Selected samples from ER-20-6{number_sign}1 were subjected to matrix and/or fracture diffusion experiments to assess solute movement in this environment. Micrographic analysis of these samples suggests that the similarity in bulk chemical composition results in very similar mineral assemblages forming along natural fractures. These samples are all part of the mafic-poor Calico Hills Formation and exhibit fracture-coating mineral assemblages dominated by mixed illite/smectite clay and illite, with local opaline silica (2,236 and 2, 812 feet), and zeolite (at 2,236 feet). Based on this small sample population,more » the magnitude to which secondary phases have formed on fracture surfaces bears an apparently inverse relationship to the competency of the host lithology, reflected by variations in the degree of fracturing and the development of secondary phases on fracture surfaces. In the flow breccia at 2,851 feet, thinly developed, localized coatings are developed along persistent open fracture apertures in this competent rock type. Fractures in the devitrified lava from 2,812 feet are irregular, and locally blocked by secondary mineral phases. Natural fractures on the zeolitized tuff from 2,236 feet are discontinuous and irregular and typically obstructed with secondary mineral phases. There are also a second set of clean fractures in the 2,236 foot sample which lack secondary mineral phases and are interpreted to have been induced by the BULLION test. Based on these results, it is expected that matrix diffusion will be enhanced in samples where potentially transmissive fractures exhibit the greatest degree of obstruction (2,236>2,812=2,835>2,851). It is unclear what influence the induced fractures observed at 2,236 feet may have on diffusion given the lack of knowledge on their extent. It is assumed that the bulk matrix diffusion characteristics of the sample at 2,835 feet will be equivalent to the unfractured characteristics of the sample at 2,812 feet.« less

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