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Title: Site Characterization Data from the U3ax/bl Exploratory Boreholes at the Nevada Test Site

Abstract

This report provides qualitative analyses and preliminary interpretations of hydrogeologic data obtained from two 45-degree, slanted exploratory boreholes drilled within the Area 3 Radioactive Waste Management Site (RWMS) at the Nevada Test Site. Borehole UE-3bl-D1 was drilled beneath the U3ax/bl mixed waste disposal unit, and Borehole UE-3bl-U1 was drilled in undisturbed alluvium adjacent to the disposal unit. The U3ax/bl disposal unit is located within two conjoined subsidence craters, U3ax and U3bl, which were created by underground nuclear testing. Data from these boreholes were collected to support site characterization activities for the U3ax/bl disposal unit and the entire Area 3 RWMS. Site characterization at disposal units within the Area 3 RWMS must address the possibility that subsidence craters and associated disturbed alluvium of the chimneys beneath the craters might serve as pathways for contaminant migration. The two boreholes were drilled and sampled to compare hydrogeologic properties of alluvium below the waste disposal unit with those of adjacent undisturbed alluvium. Whether Borehole UE-3bl-D1 actually penetrated the chimney of the U3bl crater is uncertain. Analyses of core samples showed little difference in hydrogeologic properties between the two boreholes. Important findings of this study include the following: No hazardous or radioactive constituents of wastemore » disposal concern were found in the samples obtained from either borehole. No significant differences in physical and hydrogeologic properties between boreholes is evident, and no evidence of significant trends with depth for any of these properties was observed. The values observed are typical of sandy materials. The alluvium is dry, with volumetric water content ranging from 5.6 to 16.2 percent. Both boreholes exhibit a slight increase in water content with depth, the only such trend observed. Water potential measurements on core samples from both boreholes show a large positive potential gradient (water moves upward, via evapotranspiration) for the entire vertical depth. Very little liquid flow occurs through the vadose zone. The direction of flow in the upper vadose zone (approximately the upper 35 meters) is upward, based on unsaturated hydraulic conductivity data, water potential data, and environmental tracer data.« less

Authors:
;
Publication Date:
Research Org.:
BECHTEL NEVADA
Sponsoring Org.:
USDOE
OSTI Identifier:
860153
Report Number(s):
DOE/NV/11718-003-REV.1
TRN: US0504874
DOE Contract Number:  
AC03-96NV11718
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
12 MANAGEMENT OF RADIOACTIVE WASTES, AND NON-RADIOACTIVE WASTES FROM NUCLEAR FACILITIES; BOREHOLES; CHIMNEYS; HYDRAULIC CONDUCTIVITY; LIQUID FLOW; METERS; NEVADA TEST SITE; RADIOACTIVE WASTE MANAGEMENT; SITE CHARACTERIZATION; TESTING; WASTE DISPOSAL; WATER

Citation Formats

Bechtel Nevada, and U.S. Department of Energy, National Nuclear Security Administration Nevada Site Office. Site Characterization Data from the U3ax/bl Exploratory Boreholes at the Nevada Test Site. United States: N. p., 2005. Web. doi:10.2172/860153.
Bechtel Nevada, & U.S. Department of Energy, National Nuclear Security Administration Nevada Site Office. Site Characterization Data from the U3ax/bl Exploratory Boreholes at the Nevada Test Site. United States. doi:10.2172/860153.
Bechtel Nevada, and U.S. Department of Energy, National Nuclear Security Administration Nevada Site Office. Mon . "Site Characterization Data from the U3ax/bl Exploratory Boreholes at the Nevada Test Site". United States. doi:10.2172/860153. https://www.osti.gov/servlets/purl/860153.
@article{osti_860153,
title = {Site Characterization Data from the U3ax/bl Exploratory Boreholes at the Nevada Test Site},
author = {Bechtel Nevada and U.S. Department of Energy, National Nuclear Security Administration Nevada Site Office},
abstractNote = {This report provides qualitative analyses and preliminary interpretations of hydrogeologic data obtained from two 45-degree, slanted exploratory boreholes drilled within the Area 3 Radioactive Waste Management Site (RWMS) at the Nevada Test Site. Borehole UE-3bl-D1 was drilled beneath the U3ax/bl mixed waste disposal unit, and Borehole UE-3bl-U1 was drilled in undisturbed alluvium adjacent to the disposal unit. The U3ax/bl disposal unit is located within two conjoined subsidence craters, U3ax and U3bl, which were created by underground nuclear testing. Data from these boreholes were collected to support site characterization activities for the U3ax/bl disposal unit and the entire Area 3 RWMS. Site characterization at disposal units within the Area 3 RWMS must address the possibility that subsidence craters and associated disturbed alluvium of the chimneys beneath the craters might serve as pathways for contaminant migration. The two boreholes were drilled and sampled to compare hydrogeologic properties of alluvium below the waste disposal unit with those of adjacent undisturbed alluvium. Whether Borehole UE-3bl-D1 actually penetrated the chimney of the U3bl crater is uncertain. Analyses of core samples showed little difference in hydrogeologic properties between the two boreholes. Important findings of this study include the following: No hazardous or radioactive constituents of waste disposal concern were found in the samples obtained from either borehole. No significant differences in physical and hydrogeologic properties between boreholes is evident, and no evidence of significant trends with depth for any of these properties was observed. The values observed are typical of sandy materials. The alluvium is dry, with volumetric water content ranging from 5.6 to 16.2 percent. Both boreholes exhibit a slight increase in water content with depth, the only such trend observed. Water potential measurements on core samples from both boreholes show a large positive potential gradient (water moves upward, via evapotranspiration) for the entire vertical depth. Very little liquid flow occurs through the vadose zone. The direction of flow in the upper vadose zone (approximately the upper 35 meters) is upward, based on unsaturated hydraulic conductivity data, water potential data, and environmental tracer data.},
doi = {10.2172/860153},
journal = {},
number = ,
volume = ,
place = {United States},
year = {2005},
month = {8}
}