Geochemical and Isotopic Constraints on Groundwater Flow Directions, Mixing, and Recharge at Yucca Mountain, Nevada Rev 00, ICN 00

ANL-NBS-HS-000021

August 2000

1. PURPOSE 
This analysis is governed by the Office of Civilian Radioactive Waste Management (OCRWM) 
Analysis and Modeling Report Development Plan entitled Geochemical and Isotopic 
Constraints on Groundwater Flow Directions, Mixing and Recharge at Yucca Mountain 
(CRWMS M&O 1999a). As stated in this Development Plan, the purpose of the work is to 
provide an analysis of groundwater recharge rates, flow directions and velocities, and mixing 
proportions of water from different source areas based on groundwater geochemical and isotopic 
data. The analysis of hydrochemical and isotopic data is intended to provide a basis for 
evaluating the hydrologic system at Yucca Mountain independently of analyses based purely on 
hydraulic arguments. Where more than one conceptual model for flow is possible, based on 
existing hydraulic data, hydrochemical and isotopic data may be useful in eliminating some of 
these conceptual models. 
This report documents the use of geochemical and isotopic data to constrain rates and directions 
of groundwater flow near Yucca Mountain and the timing and magnitude of recharge in the 
Yucca Mountain vicinity. The geochemical and isotopic data are also examined with regard to 
the possible dilution of groundwater recharge from Yucca Mountain by mixing with groundwater 
downgradient from the potential repository site. Specifically, the primary tasks of this report, as 
listed in the AMR Development Plan (CRWMS M&O 1999a), consist of the following: 
1. Compare geochemical and isotopic data for perched and pore water in the unsaturated zone 
with similar data from the saturated zone to determine if local recharge is present in the 
regional groundwater system 
2. Determine the timing of the recharge from stable isotopes such as deuterium (2H) and 
oxygen-18 (18O), which are known to vary over time as a function of climate, and from 
radioisotopes such as carbon-14 (14C) and chlorine-36 (36Cl) 
3. Determine the magnitude of recharge from relatively conservative tracers such as chloride 
and/or groundwater age and unsaturated-zone thickness 
4. Correct 14C ages for possible dilution of radiocarbon by calcite fracture coatings using 
geochemical reaction models 
5. Establish mixing relations between waters from different source areas using relatively 
conservative species such as 2H and 18O or chloride and sulfate, and evaluate if inferred flow 
paths and mixing relations are reasonable based on chemical reactions required to reproduce 
the observed water chemistry. 
The analysis presented in this report is appropriate for the intended use described above. This 
analysis is not directly related to the principal factors, or other factors, for the post-closure safety 
case, nor is it used directly in calculations or analyses that provide estimates of the effects of 
potentially disruptive processes and events, as described in AP-3.15Q, Managing Technical 
Product Inputs.

ANL-NBS-HS-000021, REV 00 14 of 131 August 2000 
INTENTIONALLY LEFT BLANK

ANL-NBS-HS-000021, REV 00 15 of 131 August 2000 
2. QUALITY ASSURANCE 
The activities documented in this Analysis and Modeling Report (AMR) were evaluated in 
accordance with QAP-2-0, Conduct of Activities, and were determined to be quality affecting and 
subject to the requirements of the U.S. Department of Energy (DOE) Office of Civilian 
Radioactive Waste Management (OCRWM) Quality Assurance Requirements and Description 
(QARD) (DOE 2000). This evaluation is documented in Activity Evaluation of M&O Site 
Investigations-(Q) (CRWMS M&O 1999b; 1999c) and Activity Evaluation for Work Package 
WP 1301213SM1 (Wemheuer 1999). Accordingly, the analysis activities documented in this 
AMR have been conducted in accordance with the CRWMS M&O quality assurance (QA) 
program, using approved procedures identified in CRWMS M&O (1999a). This AMR has been 
developed in accordance with procedure AP-3.10Q, Analyses and Models. The conclusions in 
this AMR do not affect the repository design or permanent items as discussed in QAP-2-3, 
Classification of Permanent Items. 
The work activities documented in the AMR depend on electronic media to store, maintain, 
retrieve, modify, update, and transmit quality affecting information. As part of the work process, 
electronic databases, spreadsheets, and sets of files were required to hold information intended 
for use to support the licensing position. In addition, the work process required the transfer of 
data and files electronically from one location to another. Consequently, all electronic files 
consisting of source data, developed model inputs, model outputs, and post-processing results 
were maintained and processed according to the seven compliance criteria listed in AP-SV.1Q, 
Control of the Electronic Management of Data, pursuant to the Work Direction and Planning 
Document governing these activities (CRWMS M&O 1999a).

ANL-NBS-HS-000021, REV 00 16 of 131 August 2000 
INTENTIONALLY LEFT BLANK

ANL-NBS-HS-000021, REV 00 17 of 131 August 2000 
3. COMPUTER SOFTWARE AND MODEL USAGE 
The following commercially available software (as per AP-SI.1Q, Software Management) was 
used in this analysis and documentation: 
 SURFER for Windows, version 6: used to create post-plots [(Golden Software 1995); 
(exempt software in accordance with AP-SI.1Q)]. 
 TECPLOT, version 7.5: used to create x-y scatterplots [(AMTEC Engineering 1998); 
(exempt software in accordance with AP-SI.1Q)]. 
This software met the acceptance criteria of being able to produce plots of acceptable graphic 
quality in formats suitable for incorporation into this AMR. 
The following public-domain geochemical software was used in this analysis: 
NETPATH, version 2.13 (Plummer et al. 1994, pp. 130; STN: 10303-2.13-00): used to 
correct carbon-14 ages for the effects of chemical reactions. (Note: NETPATH is a 
FORTRAN program running under MS-DOS; was developed by the U.S. Geological Survey 
(USGS); and was run on a COMPAQ Professional Workstation AP400, with a Intel Pentium 
II processor, manufacturers serial number AP400 400S1/1P/128/4S/2D+ DOM 
D828BZY50021, located at Los Alamos National Laboratory, TA-3, Bldg. 31.) 
This software is subject to the configuration controls and qualification processes in accordance 
with AP-SI.1Q. The software was obtained from Configuration Management, was appropriate 
for its intended use, and used only within the range of validation. The range of hydrochemical 
data used in NETPATH for this AMR is indicated by Table 3. 
The output from SURFER and TECPLOT was visually checked for correctness, and the results 
of all calculations using NETPATH were checked with order-of-magnitude estimations.

ANL-NBS-HS-000021, REV 00 18 of 131 August 2000 
INTENTIONALLY LEFT BLANK

ANL-NBS-HS-000021, REV 00 19 of 131 August 2000 
4. INPUTS 
4.1 DATA AND PARAMETERS 
Input data directly used in this analysis come from several sources that are summarized in 
Table 1. Tables 2 and 3 list the chemical and isotopic groundwater data used in the analysis, 
including not only local data for the Yucca Mountain area but also regional data for the Death 
Valley flow system and Nevada Test Site (NTS). The qualification status of data inputs is 
indicated in the electronic Document Input Reference System (DIRS) database. Data 
qualification efforts, as needed, will be conducted in accordance with AP-SIII.2Q, Qualification 
of Unqualified Data and the Documentation of Rationale for Accepted Data, and documented 
separately from this AMR. 
Table 1. Sources of Data Referenced in This Report 
Input Data for Hydrogeologic Setting, Potentiometric Surface, and Previous Work (Sections 6.2, 6.3, and 6.4) 
Data Description DTN 
Only corroborative data were used N/A 
Input Data for Areal Distributions of Chemical and Isotopic Species (Section 6.5.1) 
Data Description DTN 
Chemical and isotopic data from borehole TW-5 MO0007GNDWTRIS.004, 
MO0007MAJIONPH.002 
Chemical and isotopic data from the Nye County EWDP Wells in Amargosa Valley, 
Nevada, collected between 12/11/98 and 11/15/99. 
MO0007GNDWTRIS.012, 
MO0007MAJIONPH.015 
Chemical data from borehole NDOT collected 5/17/95 MO0007MAJIONPH.009 
Chemical and isotopic data from boreholes WT-7, WT-10, WT#12, WT#14, and WT#15 MO0007GNDWTRIS.006, 
MO0008MAJIONPH.017 
Chemical and isotopic data from the CIND-R-LITE well GS000700012847.001 
Stable isotope ratios and radiocarbon data for WT#12, WT#14, and WT#15 MO0007GNDWTRIS.007 
Chemical and isotopic data from test well UE-25 p#1, Yucca Mountain area, Nye County, 
Nevada 
MO0007GNDWTRIS.008, 
MO0007MAJIONPH.010 
Chemical and isotopic data for groundwater in the Yucca Mountain area, Nevada 1971 
1984 
MO0007GNDWTRIS.009, 
MO0007MAJIONPH.011 
Chemical analyses of water from selected wells and springs in the Yucca Mountain area, 
Nevada, and southeastern California 
MO0007MAJIONPH.012 
Chemical data from borehole USW VH-2 GS930108315213.002 
Uranium isotopic analyses of groundwaters from SW Nevada  SE California GS930108315213.004 
Chemical composition of groundwater in the Yucca Mountain area MO0007MAJIONPH.013 
Chemical and isotopic data for groundwater in the west-central Amargosa Desert, Nevada MO0007GNDWTRIS.011, 
MO0007MAJIONPH.014 
Hydrochemical data from USW VH-1, JF#3, UE-29 UZN#91, Virgin Spring, Nevares 
Spring, UE-25 J-12, UE-25 J-13, UE-22 ARMY#1, and USW UZ-14 
GS930908312323.003 
Selected groundwater data for Yucca Mountain region, southern Nevada, through 
December 1992 
MO0007GNDWTRIS.005, 
MO0007MAJIONPH.008 
Hydrochemical data base for the Death Valley Region MO0007MAJIONPH.006 
Field, chemical, and isotopic data describing water samples collected in Death Valley 
National Monument and at various boreholes in and around Yucca Mountain, Nevada, 
between 1992 and 1995 
GS950808312322.001

ANL-NBS-HS-000021, REV 00 20 of 131 August 2000 
Input Data for Areal Distributions of Chemical and Isotopic Species (Section 6.5.1) Continued 
Data Description DTN 
Uranium and thorium isotope data for waters analyzed between 1/94 and 9/96 GS960908315215.013 
d18O and dD stable isotope analyses of borehole waters from GEXA Well 4 and VH-2 GS970708312323.001 
Uranium isotopic data for SZ and UZ waters collected between 12/96 and 12/97 GS980108312322.003 
Uranium isotopic data for saturated- and unsaturated-zone waters collected by non-YMP 
personnel between May 1989 and August 1997 
GS980208312322.006 
Chemical and isotopic data for groundwater samples collected at boreholes USW UZ-14, 
UE-25 WT#3, and UE-25 WT-17 
MO0007GNDWTRIS.003, 
MO0007MAJIONPH.005 
U concentrations and 234U/238U ratios from spring, well, runoff, and rainwaters collected 
from the NTS and Death Valley vicinities and analyzed between 01/15/98 and 08/15/98 
GS980908312322.009 
Chemical composition of groundwater from UZ#16 MO0007MAJIONPH.007 
Chemical and isotopic data for borehole USW G-2 MO0007GNDWTRIS.002, 
MO0007MAJIONPH.003 
Isotopic data for borehole USW H-6 See Assumption 23 
Input Data for Regional Flow Paths Inferred from Hydrochemical Data (Section 6.5.2) 
Data Description DTN 
Chemical and isotopic data from the Nye County EWDP Wells in Amargosa Valley, 
Nevada, collected between 12/11/98 and 11/15/99. 
MO0007GNDWTRIS.012, 
MO0007MAJIONPH.015 
Chemical data from borehole NDOT collected 5/17/95 MO0007MAJIONPH.009 
Chemical and isotopic data from boreholes WT-7, WT-10, WT#12, WT#14, and WT#15 MO0007GNDWTRIS.006, 
MO0008MAJIONPH.017 
Chemical and isotopic data from the CIND-R-LITE well GS000700012847.001 
Chemical and isotopic data from test well UE-25 p#1, Yucca Mountain area, Nye County, 
Nevada 
MO0007GNDWTRIS.008, 
MO0007MAJIONPH.010 
Chemical and isotopic data for groundwater in the Yucca Mountain area, Nevada 1971 
1984 
MO0007GNDWTRIS.009, 
MO0007MAJIONPH.011 
Chemical analyses of water from selected wells and springs in the Yucca Mountain area, 
Nevada, and southeastern California 
MO0007MAJIONPH.012 
Chemical data from borehole USW VH-2 GS930108315213.002 
Chemical composition of groundwater in the Yucca Mountain area MO0007MAJIONPH.013 
Chemical and isotopic data for groundwater in the west-central Amargosa Desert, Nevada MO0007GNDWTRIS.011, 
MO0007MAJIONPH.014 
Selected groundwater data for Yucca Mountain region, southern Nevada, through 
December 1992 
MO0007GNDWTRIS.005, 
MO0007MAJIONPH.008 
Hydrochemical data base for the Death Valley Region MO0007MAJIONPH.006 
Field, chemical, and isotopic data describing water samples collected in Death Valley 
National Monument and at various boreholes in and around Yucca Mountain, Nevada, 
between 1992 and 1995 
GS950808312322.001 
Chemical and isotopic data for groundwater samples collected at boreholes USW UZ-14, 
UE-25 WT#3, and UE-25 WT-17 
MO0007GNDWTRIS.003, 
MO0007MAJIONPH.005 
Chemical composition of groundwater from UZ#16 MO0007MAJIONPH.007 
Chemical and isotopic data for borehole USW G-2 MO0007GNDWTRIS.002, 
MO0007MAJIONPH.003 
Isotopic data for borehole USW H-6 See Assumption 23

ANL-NBS-HS-000021, REV 00 21 of 131 August 2000 
Input Data for Evaluation of Evidence for Local Recharge (Section 6.5.3) 
Data Description DTN 
Chemical and isotopic data from boreholes WT-7, WT-10, WT#12, WT#14, and WT#15 MO0007GNDWTRIS.006, 
MO0008MAJIONPH.017 
Chemical and isotopic data for groundwater in the Yucca Mountain area, Nevada 1971 
1984 
MO0007GNDWTRIS.009, 
MO0007MAJIONPH.011 
Chemical analyses of water from selected wells and springs in the Yucca Mountain area, 
Nevada, and southeastern California 
MO0007MAJIONPH.012 
Chemical data from borehole USW VH-2 GS930108315213.002 
Uranium isotopic analyses of groundwaters from SW Nevada  SE California GS930108315213.004 
Chemical composition of groundwater in the Yucca Mountain area MO0007MAJIONPH.013 
Chemical and isotopic data for groundwater in the west-central Amargosa Desert, Nevada MO0007GNDWTRIS.011, 
MO0007MAJIONPH.014 
Hydrochemical data from USW VH-1, JF#3, UE-29 UZN#91, Virgin Spring, Nevares 
Spring, UE-25 J-12, UE-25 J-13, UE-22 ARMY#1, and USW UZ-14 
GS930908312323.003 
Hydrochemical data base for the Death Valley Region MO0007MAJIONPH.006 
Field, chemical, and isotopic data describing water samples collected in Death Valley 
National Monument and at various boreholes in and around Yucca Mountain, Nevada, 
between 1992 and 1995 
GS950808312322.001 
Uranium and thorium isotope data determined by mass spectrometry for dating subsurface 
secondary deposits from ESF and drill hole locations 
GS960208315215.001 
Uranium and thorium isotope data for waters analyzed between 1/94 and 9/96. GS960908315215.013 
U and Th isotope data for ESF secondary minerals collected between 3/96 and 7/96 GS960908315215.014 
Uranium and thorium isotope data collected between 9/96 and 2/97 from secondary 
minerals in the ESF 
GS970208315215.001 
Uranium-lead isotope data for ESF secondary minerals from Sep. 96 to Feb. 97 GS970208315215.002 
Uranium and thorium isotope data from secondary minerals in the ESF collected between 
2/15/97 and 9/15/97 
GS970808315215.012 
234U/238U activity ratios for perched water GS980108312322.003 
Chemical data from borehole WT-24 collected in 1997 GS980108312322.005 
Uranium isotopic data for saturated- and unsaturated-zone waters collected by non-YMP 
personnel between May 1989 and August 1997 
GS980208312322.006 
Field, chemical, and isotopic data for groundwater samples collected at boreholes USW 
UZ-14, UE-25 WT#3, and UE-25 WT-17 
MO0007GNDWTRIS.003, 
MO0007MAJIONPH.005 
U concentrations and 234U/238U ratios from spring, well, runoff, and rain waters collected 
from the NTS and Death Valley vicinities and analyzed between 01/15/98 and 08/15/98 
GS980908312322.009 
Chemical and isotopic data for borehole USW G-2 MO0007GNDWTRIS.002, 
MO0007MAJIONPH.003 
Chemical composition of groundwater from UZ#16 MO0007MAJIONPH.007 
d13C, dD, d18O, 14C data for perched water samples MO0007GNDWTRIS.013 
Chemical composition of perched water samples MO0007MAJIONPH.016 
Chlorine-36 analyses of packrat urine LAJF831222AQ98.011 
Chemical and isotopic data from the Nye County EWDP Wells in Amargosa Valley, 
Nevada, collected between 12/11/98 and 11/15/99. 
MO0007GNDWTRIS.012, 
MO0007MAJIONPH.015

ANL-NBS-HS-000021, REV 00 22 of 131 August 2000 
Input Data for Evaluation of Evidence for Timing of Recharge (Section 6.5.4) 
Data Description DTN 
Chemical and isotopic data from boreholes WT-7, WT-10, WT#12, WT#14, and WT#15 MO0007GNDWTRIS.006, 
MO0008MAJIONPH.017 
Chemical and isotopic data from the CIND-R-LITE well GS000700012847.001 
Stable isotope ratios and radiocarbon data for WT#12, WT#14, and WT#15 MO0007GNDWTRIS.007 
Chemical and isotopic data from test well UE-25 p#1, Yucca Mountain area, Nye County, 
Nevada 
MO0007GNDWTRIS.008, 
MO0007MAJIONPH.010 
Chemical and isotopic data for groundwater in the Yucca Mountain area, Nevada 1971 
1984 
MO0007GNDWTRIS.009, 
MO0007MAJIONPH.011 
Chemical analyses of water from selected wells and springs in the Yucca Mountain area, 
Nevada, and southeastern California 
MO0007MAJIONPH.012 
Chemical data from borehole USW VH-2 GS930108315213.002 
14C activities in samples from borehole a#2 MO0007GNDWTRIS.010 
Chemical and isotopic data for groundwater in the west-central Amargosa Desert, Nevada MO0007GNDWTRIS.011, 
MO0007MAJIONPH.014 
Hydrochemical data from USW VH-1, JF#3, UE-29 UZN#91, Virgin Spring, Nevares 
Spring, UE-25 J-12, UE-25 J-13, UE-22 ARMY#1, and USW UZ-14 
GS930908312323.003 
Selected groundwater data for Yucca Mountain region, southern Nevada, through 
December 1992 
MO0007GNDWTRIS.005, 
MO0007MAJIONPH.008 
Hydrochemical data base for the Death Valley Region MO0007MAJIONPH.006 
Field, chemical, and isotopic data describing water samples collected in Death Valley 
National Monument and at various boreholes in and around Yucca Mountain, Nevada, 
between 1992 and 1995 
GS950808312322.001 
d18O and d D stable isotope analyses of borehole waters from GEXA Well 4 and VH-2 GS970708312323.001 
Chemical and isotopic data for groundwater samples collected at boreholes USW UZ-14, 
UE-25 WT#3, and UE-25 WT-17 
MO0007GNDWTRIS.003, 
MO0007MAJIONPH.005 
Chemical and isotopic data for borehole USW G-2 MO0007GNDWTRIS.002, 
MO0007MAJIONPH.003 
d13C, dD, d18O, and 14C data for perched water MO0007GNDWTRIS.010 
Chlorine-36 analyses of packrat urine LAJF831222AQ98.011 
Isotopic data for borehole USW H-6 See Assumption 23 
Input Data for Evaluation of Evidence for Mixing Relations 
Between Waters from Different Sources (Section 6.5.5) 
Data Description DTN 
Chemical and isotopic data from the Nye County EWDP Wells in Amargosa Valley, 
Nevada, collected between 12/11/98 and 11/15/99. 
MO0007GNDWTRIS.012, 
MO0007MAJIONPH.015 
Chemical and isotopic data from boreholes WT-7, WT-10, WT#12, WT#14, and WT#15 MO0007GNDWTRIS.006, 
MO0008MAJIONPH.017 
Chemical and isotopic data from the CIND-R-LITE well GS000700012847.001 
Stable isotope ratios and radiocarbon data for WT#12, WT#14, and WT#15 MO0007GNDWTRIS.007 
Chemical and isotopic data from test well UE-25 p#1, Yucca Mountain area, Nye County, 
Nevada 
MO0007GNDWTRIS.008, 
MO0007MAJIONPH.010 
Chemical and isotopic data for groundwater in the Yucca Mountain area, Nevada 1971 
1984 
MO0007GNDWTRIS.009, 
MO0007MAJIONPH.011 
Chemical composition of groundwater in the Yucca Mountain area MO0007MAJIONPH.013 
Selected groundwater data for Yucca Mountain region, southern Nevada, through 
December 1992 
MO0007GNDWTRIS.005, 
MO0007MAJIONPH.008

ANL-NBS-HS-000021, REV 00 23 of 131 August 2000 
Input Data for Evaluation of Evidence for Mixing Relations 
Between Waters from Different Sources (Section 6.5.5) Continued 
Data Description DTN 
Field, chemical, and isotopic data describing water samples collected in Death Valley 
National Monument and at various boreholes in and around Yucca Mountain, Nevada, 
between 1992 and 1995 
GS950808312322.001 
d18O and d D stable isotope analyses of borehole waters from GEXA Well 4 and VH-2 GS970708312323.001 
Chemical and isotopic data for groundwater samples collected at boreholes USW UZ-14, 
UE-25 WT#3, and UE-25 WT-17 
MO0007GNDWTRIS.003, 
MO0007MAJIONPH.005 
Chemical and isotopic data for borehole USW G-2 MO0007GNDWTRIS.002, 
MO0007MAJIONPH.003 
Isotopic data for borehole USW H-6 See Assumption 23 
Input Data for Evaluation of Evidence for the Magnitude of Recharge (Section 6.5.6) 
Data Description DTN 
Chemical and isotopic data for groundwater in the Yucca Mountain area, Nevada 1971 
1984 
MO0007GNDWTRIS.009, 
MO0007MAJIONPH.011 
Chemical analyses of water from selected wells and springs in the Yucca Mountain area, 
Nevada, and southeastern California 
MO0007MAJIONPH.012 
Chemical composition of groundwater in the Yucca Mountain area MO0007MAJIONPH.013 
Chemical and isotopic data for groundwater in the west-central Amargosa Desert, Nevada MO0007GNDWTRIS.011, 
MO0007MAJIONPH.014 
Field, chemical, and isotopic data describing water samples collected in Death Valley 
National Monument and at various boreholes in and around Yucca Mountain, Nevada, 
between 1992 and 1995 
GS950808312322.001 
Chemical and isotopic data for groundwater samples collected at boreholes USW UZ-14, 
UE-25 WT#3, and UE-25 WT-17 
MO0007GNDWTRIS.003, 
MO0007MAJIONPH.005 
Chemical and isotopic data for borehole USW G-2 MO0007GNDWTRIS.002, 
MO0007MAJIONPH.003 
Chemical composition of perched water samples MO0007MAJIONPH.016 
Chemical composition of groundwater from UZ#16 MO0007MAJIONPH.007 
Apparent infiltration rates in alluvium from USW UZ-N37, USW UZ-N54, USW UZ-14 and 
UE-25 UZ#16, calculated by chloride mass balance method 
LA0002JF831222.001 
Apparent infiltration rates in PTn units from USW UZ-7a, USW UZ-N55, USW UZ-14, UE- 
25 UZ#16, USW NRG-6, USW NRG-7a, and USW SD-6, SD-7, SD-9 and SD-12, 
calculated by chloride mass balance method 
LA0002JF831222.002 
Input Data for Evaluation of Evidence for Downgradient Dilution (Section 6.5.7) 
Data Description DTN 
Chemical and isotopic data from the Nye County EWDP Wells in Amargosa Valley, 
Nevada, collected between 12/11/98 and 11/15/99. 
MO0007GNDWTRIS.012, 
MO0007MAJIONPH.015 
Chemical and isotopic data from boreholes WT-7, WT-10, WT#12, WT#14, and WT#15 MO0007GNDWTRIS.006, 
MO0008MAJIONPH.017 
Chemical and isotopic data from the CIND-R-LITE well GS000700012847.001 
Stable isotope ratios and radiocarbon data for WT#12, WT#14, and WT#15 MO0007GNDWTRIS.007 
Chemical and isotopic data from test well UE-25 p#1, Yucca Mountain area, Nye County, 
Nevada 
MO0007GNDWTRIS.008, 
MO0007MAJIONPH.010 
Chemical and isotopic data for groundwater in the Yucca Mountain area, Nevada 1971 
1984 
MO0007GNDWTRIS.009, 
MO0007MAJIONPH.011

ANL-NBS-HS-000021, REV 00 24 of 131 August 2000 
Input Data for Evaluation of Evidence for Downgradient Dilution (Section 6.5.7) Continued 
Data Description DTN 
Uranium isotopic analyses of groundwaters from SW Nevada  SE California GS930108315213.004 
Chemical composition of groundwater in the Yucca Mountain area MO0007MAJIONPH.013 
Chemical and isotopic data for groundwater in the west-central Amargosa Desert, Nevada MO0007GNDWTRIS.011, 
MO0007MAJIONPH.014 
Hydrochemical data from USW VH-1, JF#3, UE-29 UZN#91, Virgin Spring, Nevares 
Spring, UE-25 J-12, UE-25 J-13, UE-22 ARMY#1, and USW UZ-14 
GS930908312323.003 
Selected groundwater data for Yucca Mountain region, southern Nevada, through 
December 1992 
MO0007GNDWTRIS.005, 
MO0007MAJIONPH.008 
Field, chemical, and isotopic data describing water samples collected in Death Valley 
National Monument and at various boreholes in and around Yucca Mountain, Nevada, 
between 1992 and 1995 
GS950808312322.001 
Uranium and thorium isotope data for waters analyzed between 1/94 and 9/96 GS960908315215.013 
d18O and dD stable isotope analyses of borehole waters from GEXA Well 4 and VH-2 GS970708312323.001 
Uranium isotopic data for SZ and UZ waters collected between 12/96 and 12/97 GS980108312322.003 
Chemical and isotopic data for groundwater samples collected at boreholes USW UZ-14, 
UE-25 WT#3, and UE-25 WT-17 
MO0007GNDWTRIS.003, 
MO0007MAJIONPH.005 
U concentrations and 234U/238U ratios from spring, well, runoff, and rain waters collected 
from the NTS and Death Valley vicinities and analyzed between 01/15/98 and 08/15/98 
GS980908312322.009 
Chemical and isotopic data for borehole USW G-2 MO0007GNDWTRIS.002, 
MO0007MAJIONPH.003 
Isotopic data for borehole USW H-6 See Assumption 23 
The input data listed in Table 1 represent geochemical and isotopic characteristics of perched 
water and groundwater in the vicinity of Yucca Mountain and hence are appropriate for the 
intended use of this AMR. 
4.2 CRITERIA 
This AMR complies with the Department of Energy (DOE) interim guidance (Dyer 1999). 
Subparts of the interim guidance that apply to this analysis are those pertaining to the 
characterization of the Yucca Mountain site (Subpart B, Section 15), the compilation of 
information regarding geochemistry and mineral stability of the site in support of the License 
application (Subpart B, Section 21(c)(1)(ii)), and the definition of geochemical parameters and 
conceptual models used in performance assessment (Subpart E, section 114(a)). 
4.3 CODES AND STANDARDS 
No specific formally established codes or standards have been identified as applying to this 
analysis and modeling activity. This activity does not directly support License Application (LA) 
design.

ANL-NBS-HS-000021, REV 00 25 of 131 August 2000 
Table 2. Summary of Groundwater Wells and Data Sources Used in This Report 
Well 
identifier 
Abbreviation 
used in report 
Fig. 2 
sample 
UTM-X 
(m) 
UTM-Y 
(m) Areaa 
Approximate interval 
sampled (m) 
Geologic 
unitb 
Reference for sampled depth and 
chemical (C) and isotopic (I) datac 
a#2(dp) 1 247354 Th UE-29 a#2 
a#2(sh) 2 
555753 4088351 FM-N Fortymile WashNorth 
87213 Th 
DTN: MO0007GNDWTRIS.010 (I), 
MO0007MAJIONPH.013 (C) 
UE-25 J-12 J-12 3 554444 4068774 FM-N Fortymile WashNorth open borehole (226347) Tv 
UE-25 J-13 J-13 4 554017 4073517 FM-N Fortymile WashNorth open borehole (2821063) Tpt 
DTN: MO0007GNDWTRIS.010 (I), 
MO0007MAJIONPH.013 (C) 
UE-25 JF#3 JF#3 5 554498 4067974 FM-N Fortymile WashNorth open borehole (216347) Tv DTN: MO0007GNDWTRIS.005(I), 
MO0007MAJIONPH.008 (C), 
GS930908312323.003 (I) 
UE-25 WT#14 WT#14 6 552630 4077330 FM-N Fortymile WashNorth open borehole (346399) Th 
UE-25 WT#15 WT#15 7 554034 4078702 FM-N Fortymile WashNorth Open borehole (354415) Tpt 
DTN: MO0007GNDWTRIS.007 (I), 
MO0007GNDWTRIS.006 (I), 
MO0008MAJIONPH.017 (C) 
USW G-2 G-2 8 548143 4082542 YM-N Yucca MountainNorth Open borehole (5341831) Th/Tct DTN: MO0007GNDWTRIS.002 (I), 
MO0007MAJIONPH.003 (C) 
UZ-14(sh) 9 bailed (579) Tcp USW UZ-14 
UZ-14(dp) 10 
548032 4080260 YM-N Yucca MountainNorth 
bailed (655) Tcb 
DTN: MO0007GNDWTRIS.003 (I), 
MO0007MAJIONPH.005 (C) 
H-1(Tcp) 11 572687 Tcp USW H-1 
H-1(Tcb) 12 
548727 4079926 YM-N Yucca MountainNorth 
6871829 Tcb 
DTN: MO0007GNDWTRIS.010 (I), 
MO0007MAJIONPH.013 (C) 
b#1(bh) 13 open borehole (4701220) Th/Tct UE-25 b#1 
b#1(Tcb) 14 
549949 4078423 YM-N Yucca MountainNorth 
863875 Tcb 
DTN: MO0007GNDWTRIS.010 (I), 
MO0007MAJIONPH.013 (C) 
UE-25 c#1 c#1 15 550955 4075933 YM-E Yucca MountainEast open borehole (400914) Tcb/Tct 
UE-25 c#2 c#2 16 550955 4075871 YM-E Yucca MountainEast open borehole (401913) Tcb 
c#3 17 open borehole (402913) Tcb/Tct 
DTN: MO0007GNDWTRIS.009 (I), 
MO0007MAJIONPH.011 (C), 
MO0007MAJIONPH.012 (C) 
UE-25 c#3 
c#3('95) 18 
550930 4075902 YM-E Yucca MountainEast 
open borehole (402913) Tcb/Tct DTN: GS950808312322.001 (C,I) 
UE-25 ONC#1 ONC#1 19 550479.9 4076608 YM-E Yucca MountainEast open borehole (433469) Th/Tcp MO0007MAJIONPH.004 (C) 
P#1(v) 20 3811197 Tcp UE-25 p#1 
P#1(c) 21 
551501 4075659 YM-E Yucca MountainEast 
12971805 DSlm 
DTN: MO0007GNDWTRIS.009 (I), 
MO0007MAJIONPH.011 (C), 
MO0007GNDWTRIS.008 (I), 
MO0007MAJIONPH.010 (C) 
USW G-4 G-4 22 548933 4078602 YM-C Yucca MountainCentral open borehole (541915) Tct DTN: MO0007GNDWTRIS.010 (I), 
MO0007MAJIONPH.013 (C) 
USW H-3 H-3 23 547562 4075759 YM-C Yucca MountainCentral open borehole (8221220) Tct DTN: MO0007GNDWTRIS.009 (I), 
MO0007MAJIONPH.011 (C), 
MO0007MAJIONPH.012 (C) 
USW H-4 H-4 24 549188 4077309 YM-C Yucca MountainCentral open borehole (5191220) Tcb/Tct 
USW H-5 H-5 25 547668 4078841 YM-C Yucca MountainCentral open borehole (7041220) Tcb/Tct 
DTN: MO0007GNDWTRIS.010 (I), 
MO0007MAJIONPH.013 (C) 
UE-25 UZ#16 UZ#16 26 549484.9 4076986 YM-C Yucca MountainCentral 490492 Tcp DTN: MO0007MAJIONPH.007 (C)

ANL-NBS-HS-000021, REV 00 26 of 131 August 2000 
Table 2 (Continued). Sources of Groundwater Samples Used in This Report 
Well 
identifier 
Abbreviation 
used in report 
Fig. 2 
sample 
UTM-X 
(m) 
UTM-Y 
(m) Areaa 
Approximate interval 
sampled (m) 
Geologic 
unitb 
Reference for sampled depth and 
chemical (C) and isotopic (I) datac 
UE-25 WT#12 WT#12 27 550168 4070659 YM-S Yucca MountainSouth open borehole (345399) Tpt/Th DTN: MO0007GNDWTRIS.007 (I), 
MO0007GNDWTRIS.006 (I), 
MO0008MAJIONPH.017 (C) 
USW WT-17 WT-17 28 549905 4073307 YM-S Yucca MountainSouth open borehole 
(depth not reported) 
Tcp DTN: MO0007GNDWTRIS.003 (I), 
MO0007MAJIONPH.005 (C) 
UE-25 WT#3 WT#3 29 552090 4072550 YM-S Yucca MountainSouth open borehole 
(depth not reported) 
Tcb DTN: MO0007GNDWTRIS.003 (I), 
MO0007MAJIONPH.005 (C) 
H-6(bh) 30 open borehole (5261220) Tcb/Tct DTN: MO0007GNDWTRIS.010 (I), 
MO0007MAJIONPH.013 (C) 
H-6(Tct) 31 753835 Tct 
USW H-6 
H-6(Tcb) 32 
546188 4077816 CF Crater Flat 
608646 Tcb 
DTN: MO0007MAJIONPH.012 (C), 
See Assumption 23 (C,I) 
USW WT-7 WT-7 33 546151 4075474 CF Crater Flat open borehole (421491) Tv 
USW WT-10 WT-10 34 545964 4073378 CF Crater Flat open borehole (347431) Tpt 
DTN: MO0007GNDWTRIS.006 (I), 
MO0008MAJIONPH.017 (C) 
USW VH-1 VH-1 35 539976 4071714 CF Crater Flat open borehole (184762) Tcb DTN: MO0007GNDWTRIS.010 (I), 
MO0007MAJIONPH.013 (C) 
USW VH-2 VH-2 36 537738 4073214 CF Crater Flat open borehole (1641219) Tv DTN: GS930108315213.002 (C), 
GS970708312323.001 (I) 
MO0007MAJIONPH.008 (C) 
Gexa Well 4 Gexa Well 4 37 534069 4086110 CF Crater Flat open borehole (188488) Tv DTN: GS970708312323.001 (I), 
MO0007MAJIONPH.008 (C) 
NC-EWDP-2D NC-EWDP-2D 38 547744 4057164 NC-EWDP Nye County EWDP not reported not reported 
NC-EWDP-5S NC-EWDP-5S 39 555676 4058229 NC-EWDP Nye County EWDP not reported not reported 
NC-EWDP-3D NC-EWDP-3D 40 541273 4059444 NC-EWDP Nye County EWDP not reported not reported 
NC-EWDP-9S NC-EWDP-9S 41 539039 4061004 NC-EWDP Nye County EWDP not reported not reported 
NC-EWDP-1D NC-EWDP-1D 42 536768 4062502 NC-EWDP Nye County EWDP not reported not reported 
DTN: MO0007GNDWTRIS.012 (I), 
MO0007MAJIONPH.015 (C) 
CIND-R-LITE CIND-R-LITE 43 544027 4059809 NC-EWDP Nye County EWDP not reported Tv DTN: GS930108315213.002 (C), 
MO0007MAJIONPH.006 (C), 
GS000700012847.001 (C,I) 
UE-25 J-11 J-11 44 563799 4071058 JF Jackass Flats open borehole (317405) Tb DTN: MO0007MAJIONPH.012 (C) 
15S/50E-19b1 15S/50E-19b1 45 553862.5 4054720 LW Amargosa Valley 
(formerly Lathrop Wells) 
open borehole (103110) Qal DTN: MO0007MAJIONPH.006 (C) 
Airport Well Airport Well 46 552818 4054929 LW Amargosa Valley open borehole (76229) Qal DTN: MO0007MAJIONPH.008 (C) 
15S/50E-18cdc 15S/50E-18cdc 47 553934.3 4055151 LW Amargosa Valley open borehole (105120) Qal DTN: MO0007MAJIONPH.006 (C) 
Claassen 1985, Table 1, sample 34

ANL-NBS-HS-000021, REV 00 27 of 131 August 2000 
Table 2 (Continued). Sources of Groundwater Samples Used in This Report 
Well 
identifier 
Abbreviation 
used in report 
Fig. 2 
sample 
UTM-X 
(m) 
UTM-Y 
(m) Areaa 
Approximate interval 
sampled (m) 
Geologic 
unitb 
Reference for sampled depth and 
chemical (C) and isotopic (I) datac 
NDOT NDOT 48 553685 4055242 LW Amargosa Valley open borehole (105151) Qal DTN: MO0007MAJIONPH.008 (C), 
MO0007MAJIONPH.009 (C) 
15S/50E-18ccc 15S/50E-18ccc 49 553710 4055273 LW Amargosa Valley open borehole (105120) Qal DTN: MO0007MAJIONPH.006 (C), 
Claassen 1985, Table 1, sample 35 
16S/48E-23da 16S/48E-23da 51 542391 4044364 FMW-S Fortymile WashSouth open borehole (24140) Qal DTN: MO0007MAJIONPH.006 (C) 
Claassen 1985, Table 1, sample 53 
15S/49E-22a1 15S/49E-22a1 52 550086.3 4054974 FMW-S Fortymile WashSouth open borehole (90174) Qal DTN: MO0007MAJIONPH.006 (C) 
16S/49E-05acc 16S/49E-05acc 53 546664.5 4049439 FMW-S Fortymile WashSouth open borehole (2190) Qal DTN: MO0007MAJIONPH.012 (C), 
MO0007GNDWTRIS.011 (I), 
MO0007MAJIONPH.014 (C), 
Claassen 1985, Table 1, sample 4 
15S/49E-27acc 15S/49E-27acc 54 549552.9 4052722 FMW-S Fortymile WashSouth open borehole (73467) Qal DTN: MO0007MAJIONPH.012 (C) 
15S/49E-22dcc 15S/49E-22dcc 55 549672.5 4053523 FMW-S Fortymile WashSouth open borehole (78148) Qtal DTN: MO0007MAJIONPH.006 (C), 
MO0007GNDWTRIS.011 
(I, Amargosa Well 3) 
15S/49E-22dc 15S/49E-22dc 56 549697 4053524 FMW-S Fortymile WashSouth open borehole (78150) Qal DTN: MO0007MAJIONPH.012 (C), 
MO0007GNDWTRIS.011 (I), 
MO0007MAJIONPH.014 (C), 
Claassen 1985, Table 1, sample 3 
16S/49E-8abb 16S/49E-8abb 57 546695 4048453 FMW-S Fortymile WashSouth open borehole (4560) Qal DTN: MO0007MAJIONPH.012 (C), 
MO0007GNDWTRIS.011 (I), 
MO0007MAJIONPH.014 (C), 
Claassen 1985, Table 1, sample 5 
16S/49E-8acc 16S/49E-8acc 58 546723 4047806 FMW-S Fortymile WashSouth open borehole (4590) Qal DTN: MO0007MAJIONPH.012 (C), 
Claassen 1985, Table 1, sample 6 
16S/49E-9cda 16S/49E-9cda 59 548168 4047291 FMW-S Fortymile WashSouth open borehole (4690) Qal DTN: MO0007MAJIONPH.012 (C), 
Claassen 1985, Table 1, sample 7 
16S/49E-9dcc 16S/49E-9dcc 60 548343 4047045 FMW-S Fortymile WashSouth open borehole (4960) Qal DTN: MO0007MAJIONPH.012 (C), 
MO0007GNDWTRIS.011 (I), 
MO0007MAJIONPH.014 (C), 
Claassen 1985, Table 1, sample 8 
16S/49E-18dc 16S/49E-18dc 61 545144 4045579 FMW-S Fortymile WashSouth open borehole (33110) Qal DTN: MO0007MAJIONPH.012 (C), 
MO0007GNDWTRIS.011 (I), 
MO0007MAJIONPH.014 (C), 
Claassen 1985, Table 1, sample 9 
16S/49E-16ccc 16S/49E-16ccc 62 547508 4045222 FMW-S Fortymile WashSouth open borehole 
(depth not reported) 
Qal DTN: MO0007MAJIONPH.012 (C), 
MO0007GNDWTRIS.011 (I), 
MO0007MAJIONPH.014 (C), 
Claassen 1985, Table 1, sample 10

ANL-NBS-HS-000021, REV 00 28 of 131 August 2000 
Table 2 (Continued). Sources of Groundwater Samples Used in This Report 
Well 
identifier 
Abbreviation 
used in report 
Fig. 2 
sample 
UTM-X 
(m) 
UTM-Y 
(m) Areaa 
Approximate interval 
sampled (m) 
Geologic 
unitb 
Reference for sampled depth and 
chemical (C) and isotopic (I) datac 
16S/49E-19daa 16S/49E-19daa 63 545777 4044535 FMW-S Fortymile WashSouth open borehole (3090) Qal DTN: MO0007MAJIONPH.012 (C), 
MO0007GNDWTRIS.011 (I), 
MO0007MAJIONPH.014 (C), 
Claassen 1985, Table 1, sample 11 
16S/48E-24aaa 16S/48E-24aaa 64 544077 4045235 FMW-S Fortymile WashSouth open borehole (29150) Qal DTN: MO0007MAJIONPH.012 (C), 
Claassen 1985, Table 1, sample 12 
16S/48E-25aa 16S/48E-25aa 65 544160 4043602 FMW-S Fortymile WashSouth open borehole (2650) Qal DTN: MO0007MAJIONPH.012 (C), 
MO0007GNDWTRIS.011 (I), 
MO0007MAJIONPH.014 (C), 
Claassen 1985, Table 1, sample 13 
16S/48E-36aaa 16S/48E-36aaa 66 544168 4042031 FMW-S Fortymile WashSouth open borehole (2150) Qal DTN: MO0007MAJIONPH.012 (C), 
MO0007GNDWTRIS.011 (I), 
MO0007MAJIONPH.014 (C), 
Claassen 1985, Table 1, sample 14 
17S/48E-1ab 17S/48E-1ab 67 544152 4040182 FMW-S Fortymile WashSouth open borehole (1660) Qal DTN: MO0007MAJIONPH.012 (C), 
MO0007GNDWTRIS.011 (I), 
MO0007MAJIONPH.014 (C), 
Claassen 1985, Table 1, sample 15 
17S/49E-7bb 17S/49E-7bb 68 544758 4038645 FMW-S Fortymile WashSouth open borehole (12150) Qal DTN: MO0007MAJIONPH.012 (C), 
MO0007GNDWTRIS.011 (I), 
MO0007MAJIONPH.014 (C), 
Claassen 1985, Table 1, sample 16 
17S/49E-8ddb 17S/49E-8ddb 69 547575 4037612 FMW-S Fortymile WashSouth Open borehole (15100) Qal DTN: MO0007MAJIONPH.012 (C), 
MO0007GNDWTRIS.011 (I), 
MO0007MAJIONPH.014 (C), 
Claassen 1985, Table 1, sample 18 
16S/49E-23add 16S/49E-23add 70 551958 4045217 FMW-S Fortymile WashSouth open borehole 
(depth not reported) 
Qal DTN: MO0007MAJIONPH.012 (C), 
MO0007GNDWTRIS.011 (I), 
MO0007MAJIONPH.014 (C), 
Claassen 1985, Table 1, sample 21 
16S/48E-23bdb 16S/48E-23bdb 71 541469 4044729 FMW-S Fortymile WashSouth open borehole (2950) Qal DTN: MO0007MAJIONPH.012 (C), 
Claassen 1985, Table 1, sample 24 
16S/48E-36dcc 16S/48E-36dcc 72 543530 4040395 FMW-S Fortymile WashSouth open borehole (13120) Qal DTN: MO0007MAJIONPH.012 (C), 
Claassen 1985, Table 1, sample 26 
17S/49E-9aa 17S/49E-9aa 73 549262 4038515 FMW-E Fortymile WashEast open borehole 
(depth not reported) 
Qal DTN: MO0007MAJIONPH.012 (C), 
MO0007GNDWTRIS.011 (I), 
MO0007MAJIONPH.014 (C), 
Claassen 1985, Table 1, sample 17

ANL-NBS-HS-000021, REV 00 29 of 131 August 2000 
Table 2 (Continued). Sources of Groundwater Samples Used in This Report 
Well 
identifier 
Abbreviation 
used in report 
Fig. 2 
sample 
UTM-X 
(m) 
UTM-Y 
(m) Areaa 
Approximate interval 
sampled (m) 
Geologic 
unitb 
Reference for sampled depth and 
chemical (C) and isotopic (I) datac 
17S/49E-15bbd 17S/49E-15bbd 74 549843 4036855 FMW-E Fortymile WashEast open borehole (17110) Qal DTN: MO0007MAJIONPH.012 (C), 
MO0007GNDWTRIS.011 (I), 
MO0007MAJIONPH.014 (C), 
Claassen 1985, Table 1, sample 19 
17S/49E-35ddd 17S/49E-35ddd 75 552739 4031202 FMW-E Fortymile WashEast discharge, Ash Tree Spring Qal DTN: MO0007MAJIONPH.012 (C), 
MO0007GNDWTRIS.011 (I), 
MO0007MAJIONPH.014 (C), 
Claassen 1985, Table 1, sample 20 
17S/49E-15bc 17S/49E-15bc 76 549870 4036577 FMW-E Fortymile WashEast open borehole 
(depth not reported) 
Qal DTN: MO0007MAJIONPH.012 (C), 
Claassen 1985, Table 1, sample 38 
16S/48E-15dda 16S/48E-15dda 77 540893 4045620 FMW-W Fortymile WashWest open borehole 
(depth not reported) 
Qal DTN: MO0007MAJIONPH.012 (C), 
Claassen 1985, Table 1, sample 22 
16S/48E-15aaa 16S/48E-15aaa 78 540838 4046636 FMW-W Fortymile WashWest open borehole (2950) Qal DTN: MO0007MAJIONPH.012 (C), 
MO0007GNDWTRIS.011 (I), 
MO0007MAJIONPH.014 (C), 
Claassen 1985, Table 1, sample 23 
16S/48E-10cba 16S/48E-10cba 79 539766 4047463 FMW-W Fortymile WashWest open borehole 
(depth not reported) 
Qal DTN: MO0007MAJIONPH.012 (C), 
MO0007GNDWTRIS.011 (I), 
MO0007MAJIONPH.014 (C), 
Claassen 1985, Table 1, sample 25 
16S/48E-15ba 16S/48E-15ba 80 539670 4046693 FMW-W Fortymile WashWest open borehole (3050) Qal DTN: MO0007MAJIONPH.012 (C), 
Claassen 1985, Table 1, sample 37 
TW-5 TW-5 81 562604 4054686 SH Skeleton Hills open borehole (207244) Qal DTN: MO0007MAJIONPH.006 (C) 
MO0007GNDWTRIS.004 (I), 
MO0007MAJIONPH.002 (C), 
16S/50E-7bcd 16S/50E-7bcd 82 553757 4047786 SH Skeleton Hills open borehole (4360) Qal DTN: MO0007MAJIONPH.012 (C), 
MO0007GNDWTRIS.011 (I), 
MO0007MAJIONPH.014 (C), 
Claassen 1985, Table 1, sample 27 
16S/49E-12ddd 16S/49E-12ddd 83 553834 4047386 SH Skeleton Hills open borehole 
(depth not reported) 
Qal DTN: MO0007MAJIONPH.012 (C). 
Claassen 1985, Table 1, sample 28 
16S/49E-15aaa 16S/49E-15aaa 84 550556 4046842 SH Skeleton Hills open borehole (51120) Qal DTN: MO0007MAJIONPH.012 (C), 
MO0007GNDWTRIS.011 (I), 
MO0007MAJIONPH.014 (C), 
Claassen 1985, Table 1, sample 29 
16S/49E-36aaa 16S/49E-36aaa 85 553569 4042053 GF Gravity Fault open borehole 
(depth not reported) 
Qal DTN: MO0007GNDWTRIS.011 (I), 
MO0007MAJIONPH.014 (C), 
Claassen 1985, Table 1, sample 30 
16S/49E-36aba 16S/49E-36aba 86 553222 4041836 GF Gravity Fault open borehole 
(depth not reported) 
Qal DTN: MO0007MAJIONPH.012 (C), 
Claassen 1985, Table 1, sample 31

ANL-NBS-HS-000021, REV 00 30 of 131 August 2000 
Table 2 (Continued). Sources of Groundwater Samples Used in This Report 
Well 
identifier 
Abbreviation 
used in report 
Fig. 2 
sample 
UTM-X 
(m) 
UTM-Y 
(m) Areaa 
Approximate interval 
sampled (m) 
Geologic 
unitb 
Reference for sampled depth and 
chemical (C) and isotopic (I) datac 
16S/49E-35aaa 16S/49E-35aaa 87 551980 4041520 GF Gravity Fault open borehole 
(depth not reported) 
Qal DTN: MO0007MAJIONPH.012 (C), 
Claassen 1985, Table 1, sample 32 
16S/49E-35baa 16S/49E-35baa 88 551307 4042040 GF Gravity Fault open borehole 
(depth not reported) 
Qal DTN: MO0007MAJIONPH.012 (C), 
Claassen 1985, Table 1, sample 33 
17S/49E-11ba 17S/49E-11ba 89 551873 4038623 GF Gravity Fault open borehole 
(depth not reported) 
Qal DTN: MO0007MAJIONPH.012 (C), 
Claassen 1985, Table 1, sample 36 
18S/50E-6dac 18S/50E-6dac 90 556035 4029960 GF Gravity Fault open borehole 
(depth not reported) 
Qal DTN: MO0007MAJIONPH.012 (C), 
Claassen 1985, Table 1, sample 43 
17S/50E-19aab 17S/50E-19aab 91 555998 4035691 GF Gravity Fault open borehole 
(depth not reported) 
Qal DTN: MO0007MAJIONPH.012 (C), 
Claassen 1985, Table 1, sample 58 
18S/50E-7aa 18S/50E-7aa 92 556040 4029158 GF Gravity Fault open borehole 
(depth not reported) 
Qal DTN: MO0007MAJIONPH.014 (C), 
Claassen 1985, Table 1, sample 59 
17S/49E-28bcd 17S/49E-28bcd 93 548370 4033395 AR/FMW Amargosa River / 
Fortymile Wash 
open borehole 
(depth not reported) 
Qal DTN: MO0007MAJIONPH.012 (C) 
18S/49E-1aba 18S/49E-1aba 94 554035 4031056 AR/FMW Amargosa River / 
Fortymile Wash 
0 Qal DTN: MO0007MAJIONPH.014 (C), 
Claassen 1985, Table 1, sample 40 
18S/49E-2cbc 18S/49E-2cbc 95 551377 4030023 AR/FMW Amargosa River / 
Fortymile Wash 
open borehole (22160) Qal DTN: MO0007MAJIONPH.012 (C), 
Claassen 1985, Table 1, sample 41 
18S/49E-11bbb 18S/49E-11bbb 96 551307 4029283 AR/FMW Amargosa River / 
Fortymile Wash 
open borehole 
(depth not reported) 
Qal DTN: MO0007MAJIONPH.012 (C), 
Claassen 1985, Table 1, sample 42 
17S/49E-29acc 17S/49E-29acc 97 547349 4033420 AR/FMW Amargosa River / 
Fortymile Wash 
open borehole 
(depth not reported) 
Qal DTN: MO0007MAJIONPH.012 (C), 
Claassen 1985, Table 1, sample 44 
16S/48E-8ba 16S/48E-8ba 98 536979 4048129 AR Amargosa River open borehole (3480) Qal DTN: MO0007MAJIONPH.012 (C), 
Claassen 1985, Table 1, sample 45 
16S/48E-7bba 16S/48E-7bba 99 534791 4048366 AR Amargosa River open borehole 
(depth not reported) 
Qal DTN: MO0007MAJIONPH.012 (C), 
Claassen 1985, Table 1, sample 46 
16S/48E-7cbc 16S/48E-7cbc 100 534546 4047441 AR Amargosa River open borehole 
(depth not reported) 
Qal DTN: MO0007MAJIONPH.012 (C), 
MO0007GNDWTRIS.011 (I), 
MO0007MAJIONPH.014 (C), 
Claassen 1985, Table 1, sample 47 
16S/48E-18bcc 16S/48E-18bcc 101 534827 4045747 AR Amargosa River open borehole 
(depth not reported) 
Qal DTN: MO0007MAJIONPH.012 (C), 
Claassen 1985, Table 1, sample 48 
16S/48E-17ccc 16S/48E-17ccc 102 536122 4045106 AR Amargosa River open borehole 
(depth not reported) 
Qal DTN: MO0007MAJIONPH.012 (C), 
Claassen 1985, Table 1, sample 49 
16S/48E-18dad 16S/48E-18dad 103 536069 4045814 AR Amargosa River open borehole 
(depth not reported) 
Qal DTN: MO0007MAJIONPH.012 (C), 
MO0007GNDWTRIS.011 (I), 
MO0007MAJIONPH.014 (C), 
Claassen 1985, Table 1, sample 50

ANL-NBS-HS-000021, REV 00 31 of 131 August 2000 
Table 2 (Continued). Sources of Groundwater Samples Used in This Report 
Well 
identifier 
Abbreviation 
used in report 
Fig. 2 
sample 
UTM-X 
(m) 
UTM-Y 
(m) Areaa 
Approximate interval 
sampled (m) 
Geologic 
unitb 
Reference for sampled depth and 
chemical (C) and isotopic (I) datac 
16S/48E-8cda 16S/48E-8cda 104 537063 4045941 AR Amargosa River open borehole 
(depth not reported) 
Qal DTN: MO0007MAJIONPH.012 (C), 
Claassen 1985, Table 1, sample 51 
16S/48E-17abb 16S/48E-17abb 105 537035 4046681 AR Amargosa River open borehole (3190) Qal DTN: MO0007MAJIONPH.012 (C), 
Claassen 1985, Table 1, sample 52 
27N/4E-27bbb 27N/4E-27bbb 106 541520 4034130 AR Amargosa River open borehole (1490) Qal DTN: MO0007MAJIONPH.012 (C), 
Claassen 1985, Table 1, sample 54 
Nucl. Eng. Co. NEC Well 107 527519 4068738 AR Amargosa River open borehole (86180) Qal DTN: MO0007GNDWTRIS.011 (I), 
MO0007MAJIONPH.014 (C), 
Claassen 1985, Table 1, sample 60 
DTN: As listed in the reference column of this table 
NOTES: aSee Figure 2 and Section 6.5.1 for a definition of subareas in the vicinity of Yucca Mountain. 
bGeologic units: Qal Quaternary alluvium; Qtal Quaternary-Tertiary alluvium; Tv Tertiary volcanic rocks; Tb Tertiary basalts; Tpt Tertiary Topopah Spring Member of 
Paintbrush Tuff; Tct Tertiary Crater Flat Tuff; Th Tertiary tuffaceous beds of Calico Hills; Tac Calico Hills Formation; Tcb Tertiary Bullfrog Member of Crater Flat Tuff; Tcp 
Tertiary Prow Pass Member of Crater Flat Tuff; DSlm Devonian and Silurian Lone Mountain Dolomite (Oliver and Root 1997, p. 5; Buesch et al. 1996, Table 4; Day et al. 
1998, map sheet 2). Also, see stratigraphy column in Figure 3. 
cC: the DTN or reference was the source for chemical data for this well; I: the DTN or reference was the source for isotopic data for this well. References to sample 
identifiers in Claassen (1985, Table 1) provide traceability between identifiers used in the listed DTNs and those listed in column 1 of this table.

ANL-NBS-HS-000021, REV 00 32 of 131 August 2000 
Table 3. Chemical and Isotopic Compositions of Groundwater Samples Used in This Report (data sources listed in Table 2) 
Chemical concentrations (mg L1) Isotopic analyses Calculated valuesb Fig. 2 
Well 
Namea 
Fig. 2 
sample 
No. Area pH Ca Mg Na K Cl SO4 HCO3 SiO2 
d  13C 
(per mil) 
14C activity 
(pmc) 
d  D 
(per mil) 
d  18O 
(per mil) 
log PCO2 
(atm) IAP/Kcal 
(Ca+Mg)/ (Na+K) 
(meq meq1) 
a#2(dp) 1 FM-N 7.2 10 0.2 44 1.1 11 22 107 44 12.6 62.3 93.5 12.8 2.164 0.07 0.265 
a#2(sh) 2 FM-N 7.0 10 0.3 44 1.3 8.8 21 107 44 13.1 60.0 93.0 12.8 1.978 0.041 0.269 
J-12 3 FM-N 7.1 14 2.1 38 5.1 7.3 22 119 54 7.9 32.2 97.5 12.8 2.008 0.09 0.489 
J-13 4 FM-N 7.2 12 2.1 42 5 7.1 17 124 57 7.3 29.2 97.5 13.0 2.063 0.116 0.395 
JF#3 5 FM-N 7.7 18 3.1 38 8.9 10 30 120 56 8.6 30.7 97 13.2 2.613 0.439 0.613 
WT#14 6 FM-N 7.3 10 0.8 45 5 8.2 22 119 57 12.75 24.1 97.5 12.75 2.154 0.107 0.271 
WT#15 7 FM-N 7.5 12 1.7 62 4.6 12 16 166 52 11.8 21.6 97.5 13.2 2.26 0.27 0.262 
G-2 8 YM-N 7.5 7.7 0.47 46 5.3 6.5 15 121 51 11.8 20.5 98.8 13.33 2.352 0.161 0.198 
UZ-14(sh) c 9 YM-N 8.4 0.48 0.023 70.0 1.9 6.7 14 133 44 14.1 24.6 100.4 14.0   0.008 
UZ-14(dp) c 10 YM-N 8.4 0.21 0.030 74 1.9 7.7 14 137 47 14.4 21.1 100.6 14.0   0.004 
H-1(Tcp) 11 YM-N 7.7 4.5 <0.1 51 2.4 5.7 18 115 47  19.9 103 13.4 2.583 0.136 0.102 
H-1(Tcb) 12 YM-N 7.5 6.2 <0.1 51 1.6 5.8 19 122 40 11.4 23.9 101 13.5 2.345 0.132 0.141 
b#1(bh)c 13 YM-N 7.3 18 0.66 49.5 3.6 10.75 23 156 52.5 10.55 16.7 100.3 13.4 2.036 0.318 0.424 
b#1(Tcb) 14 YM-N 7.1 18 0.72 46 2.8 7.5 21 133 51 8.6 18.9 99.5 13.5 1.892 0.175 0.462 
c#1 15 YM-E 7.6 11 0.34 56 2.0 7.4 23 151 56 7.1 15 102 13.5 2.309 0.426 0.232 
c#2 16 YM-E 7.7 12 0.4 54 2.1 7.1 22 139 54 7 16.6 100 13.4 2.454 0.524 0.263 
c#3 17 YM-E 7.7 11 0.4 55 1.9 7.2 22 137 53 7.5 15.7 103 13.5 2.458 0.479 0.238 
c#3('95) 18 YM-E 7.7 11 0.3 57 1.9 6.5 19 141 58   99.7 13.38 2.4 0.471 0.227 
ONC#1 19 YM-E 8.7 13 1.1 51 3.6 7.1 24 115d 27       0.32 
p#1(v) 20 YM-E 6.8 37 10 92 5.6 13 38 344 49 4.2 3.5 106 13.5 1.229 0.397 0.644 
P#1(c) 21 YM-E 6.6 100 39 150 12 28 160 694 41 2.3 2.3 106 13.8 0.661 1.404 1.2 
G-4 22 YM-C 7.7 13 0.2 57 2.1 5.9 19 139 45 9.1 22 103 13.8 2.488 0.494 0.263 
H-3 23 YM-C 9.2 0.8 0.02 120 1.1 9.5 31 274 43 4.9 10.5 101 13.9 3.854 0.808 0.008 
H-4 24 YM-C 7.4 17 0.29 73 2.6 6.9 26 173 46 7.4 11.8 104 14.0 2.099 0.377 0.269 
H-5 c 25 YM-C 7.85 1.95 0.01 60 2.1 6.1 16 126.5 48 10.3 19.8 102 13.6 2.729 0.109 0.037 
UZ#16 26 YM-C  11.4 1.6 79.2  10.6 29.1 210 36.2       0.547 
WT#12 27 YM-S 7.6 15 0.3 66 2.6 7.8 28 167 47 8.1 11.4 102.5 13.75 2.303 0.469 0.263 
WT-17 c 28 YM-S 7.1 8.9 0.85 49.0 2.6 6.4 17.5 129.5 39.0 8.3 16.2 101.9 13.7   0.234 
WT#3 c 29 YM-S 7.6 11.2 1.0 49.0 3.9 6.0 18.3 138.5 56.2 8.2 22.3 102.1 13.6   0.287

ANL-NBS-HS-000021, REV 00 33 of 131 August 2000 
Table 3 (Continued). Chemical and Isotopic Compositions of Groundwater Samples Used in This Report (data sources listed in Table 2) 
Chemical concentrations (mg L1) Isotopic analyses Calculated valuesb Fig. 2 
Well 
Namea 
Fig. 2 
sample 
No. Area pH Ca Mg Na K Cl SO4 HCO3 SiO2 
d  13C 
(per mil) 
14C activity 
(pmc) 
d  D 
(per mil) 
d  18O 
(per mil) 
log PCO2 
(atm) IAP/Kcal 
(Ca+Mg)/ (Na+K) 
(meq meq1) 
H-6(bh) 30 CF 8.1 4.1 0.09 86 1.3 7.6 29 182 48 7.5 16.3 106 13.8 2.764 0.501 0.056 
H-6(Tct) 31 CF 8.3 1.4 0.02 88 1.3 7.2 25 217 47 7.3 10.0 105 14.0 2.868 0.342 0.019 
H-6(Tcb) 32 CF 8.3 4.7 0.07 88 1.4 7.4 32 234 49 7.1 12.4 107 14.0 2.868 1.071 0.062 
WT-7 33 CF 8.7 2.6 0.18 97 2.1 13 7.2 252 20 9.01   13.95 3.272 1.36 0.034 
WT-10c 34 CF 8.4 2.6 0.045 94.5 1 7.8 33.5 186 46.5 6.1 7.3 103 13.82 3.055 0.603 0.032 
VH-1c 35 CF 7.6 10.3 1.53 79 1.9 10.33 44.33 164.7 49.7 8.5 12.2 108 14.2 2.355 0.411 0.184 
VH-2c 36 CF 7.1 78.5 29.75 70.8 8.1 16 142.5 391.8 26.25   99.4 13.4   1.937 
Gexa Well 4c 37 CF 7.9 11.5 0.37 71 3.25 13.5 45.5 150 48   105.55 14.1   0.191 
NC-EWDP-2Dc 38 NC-EWDP 7.5 19 1.2 42 4.1 6.1 22 149 49 8.3 23.5 104 14.1   0.57 
NC-EWDP-5Sc 39 NC-EWDP 8.3 17 3.5 149 11 39 146     107 14   0.177 
NC-EWDP-3Dc 40 NC-EWDP 8.4 0.51 0.07 113 3.0 9.0 45 223 54 6.8 10 105.6 14.4    
NC-EWDP-9Sc 41 NC-EWDP 8.0 20.3 7.7 76 4.3 11.0 61.7 212 52 6.5  104.2 14.0    
NC-EWDP-1Dc 42 NC-EWDP 7.2 55.5 31 73.5 10 16 136 369 46.5 4.5  101.3 13.5    
CIND-R-LITEc 43 NC-EWDP 7.8 12.33 6.17 71.7 3.97 9.23 46 193.7 54.3   102 13.65   0.349 
J-11 44 JF 7.6 82 13 143 15 18 449 102 68       0.782 
15S/50E-19b1 45 LW 8.1 20 3.9 107.5 6 17.5 127.5 167.5 43       0.273 
Airport Well 46 LW 9 5.6 0.23 70 1.5 10 46 110 40       0.097 
15S/50E-18cdc 47 LW 8 12 0.5 93 3.9 13.1 100 157 34       0.159 
NDOTc 48 LW 8 16.33 0.813 101.3 3.83 14.67 110 160 43.7       0.196 
15S/50E-18ccc 49 LW 8.4 16.8 0.5 93.1 3.9 13.1 100 157 34.3       0.212 
16S/48E-23da 51 FMW-S 8.2 22 2.2 69 6.6 26.6 67.2 134.2        0.4 
15S/49E-22a1 52 FMW-S 8 25 2.4 41 5.2 8 33 145 52       0.754 
16S/49E-05acc 53 FMW-S 8.1 29 2.2 35 5.1 6 26 135 62 7.1 19.3 103 13.2   0.982 
15S/49E-27acc 54 FMW-S 7.8 22 1.6 48 2.9 7.3 36 151 19       0.569 
15S/49E-22dcc 55 FMW-S 6.7 27 2.0 43 4.6 8.5 33 149 49 10.2 15.6 102 12.8   0.760 
15S/49E-22dcc 56 FMW-S 7.8 26.9 1.9 43 4.7 8.5 32.7 148.9 49.3  15.6 102 12.8   0.75 
16S/49E-8abb 57 FMW-S 7.5 30.1 2.7 37 5.5 7.8 29.8 151.9 54.1 6.8 21.4 99.5 13.2   0.98 
16S/49E-8acc 58 FMW-S 7.9 22.8 2.4 37 6.6 6.0 28.8 137.9 58.3       0.75 
16S/49E-9cda 59 FMW-S 7.6 30.5 3.4 51 8.6 12.1 64.4 143.4 65.5       0.74

ANL-NBS-HS-000021, REV 00 34 of 131 August 2000 
Table 3 (Continued). Chemical and Isotopic Compositions of Groundwater Samples Used in This Report (data sources listed in Table 2) 
Chemical concentrations (mg L1) Isotopic analyses Calculated valuesb Fig. 2 
Well 
Namea 
Fig. 2 
sample 
No. Area pH Ca Mg Na K Cl SO4 HCO3 SiO2 
d  13C 
(per mil) 
14C activity 
(pmc) 
d  D 
(per mil) 
d  18O 
(per mil) 
log PCO2 
(atm) IAP/Kcal 
(Ca+Mg)/ (Na+K) 
(meq meq1) 
16S/49E-9dcc 60 FMW-S 8.2 22.8 2.7 56.1 9.0 9.9 67.2 140.9 72.1 7.3 21.9 103 13.4   0.51 
16S/49E-18dc 61 FMW-S 8.1 20.0 2.7 42.1 9.0 7.4 27.9 150.1 58.9  28.4 102 12.6   0.59 
16S/49E-16ccc 62 FMW-S 7.9 30.1 1.9 39.8 4.3 8.2 50.9 132.4 76.9 5.2 24.8 97.5 13.2   0.9 
16S/49E-19daa 63 FMW-S 8.2 24.0 1.2 36.1 8.2 6.7 32.7 134.2 75.1  20.8 101 13.1   0.73 
16S/48E-24aaa 64 FMW-S 8.1 18.0 0.7 54 7.0 7.8 29.8 147.1 78.7       0.38 
16S/48E-25aa 65 FMW-S 8.1 18.8 0.7 43 7.4 9.2 27.9 133.0 72.1  19.3 102 13.0   0.49 
16S/48E-36aaa 66 FMW-S 8.4 16.8 1.9 40 6.3 6.7 25.0 133.0 78.7   98.5 12.6   0.53 
17S/48E-1ab 67 FMW-S 8.2 18.8 1.5 40 7 6.4 25.0 134.8 78.7  18.4 104 13.0   0.55 
17S/49E-7bb 68 FMW-S 8.3 24.0 1.7 48 7.4 9.6 30.7 153.2 79.9  10.0 104 12.7   0.59 
17S/49E-8ddb 69 FMW-S 8.4 20.8 2.7 36.1 7.4 6.4 26.9 123.3 80.8  27.8 102 13.0   0.72 
16S/49E-23add 70 FMW-S 8.2 16 1.7 55.9 6.5 8.9 34.6 126.9 76.3 8.4 27.4 99 13.2   0.36 
16S/48E-23bdb 71 FMW-S 7.3 9.2 1.0 66.0 6.6 8.9 26.9 156.2 73.9       0.18 
16S/48E-36dcc 72 FMW-S 7.2 54.9 9.7 100.0 12.9 33.0 110.5 300.2 70.3       0.76 
17S/49E-9aa 73 FMW-E 8.0 24.8 3.6 48.0 9.8 9.9 69.2 131.2 70.3  18.9 105 12.8   0.66 
17S/49E-15bbd 74 FMW-E 8.1 20.8 3.9 31.3 8.2 9.9 34.6 120.2 72.7  40.3     0.87 
17S/49E-35ddd 75 FMW-E 8.0 15.2 4.6 50.6 8.2 6.7 40.3 157.4 81.1  13.8 102 12.4   0.47 
17S/49E-15bc 76 FMW-E 8.2 21.6 1.0 39.1 6.6 10.6 27.9 122.0        0.62 
16S/48E-15dda 77 FMW-W 8.0 20.0 5.8 70.8 7.4 17.4 37.5 175.7 71.5       0.45 
16S/48E-15aaa 78 FMW-W 8.1 9.6 3.2 57.9 5.9 7.4 27.9 153.2 67.9 7.1 17.1 103 13.4   0.28 
16S/48E-10cba 79 FMW-W 8.3 9.2 3.9 60.9 5.5 8.2 32.7 166 64.3 5.6 15.6 102 13.4   0.28 
6S/48E-15ba 80 FMW-W 8 60.1 7.8 147.1 9.8 65.6 198.8 264.2 37.3       0.55 
TW-5 81 SH 7.9 33 17 130 12 21 99 395 19   113.2 15.4   0.51 
16S/50E-7bcd 82 SH 7.6 47.7 17.5 111.5 12.9 29.1 151.8 291.7 28.8 3.6 7.0 105 13.8   0.74 
16S/49E-12ddd 83 SH 7.6 45.7 17 120.0 4.3 24.1 160.4 288.6 20.4       0.69 
16S/49E-15aaa 84 SH 7.7 40.9 7.5 80.0 9.8 23 129.7 195.3 46.3 3.4  105 13.8   0.71 
16S/49E-36aaa 85 GF 7.8 52.1 22.1 120.0 18.0 26.9 168.1 314.2 37.9 4.4 10.3 104 13.7   0.78 
16S/49E-36aba 86 GF 7.7 44.9 19.9 110.1 16.8 24.1 155.6 292.9 42.7       0.74 
16S/49E-35aaa 87 GF 7.7 44.1 16.0 120.0 16.0 29.1 147.9 271.5 36.7       0.63 
16S/49E-35baa 88 GF 7.4 53.3 18.0 113.1 13.3 31.2 170 302.7 37.9       0.79 
17S/49E-11ba 89 GF 8.1 40.1 14.1 97.0 14.1 28.0 160.4 209.9 52.9       0.69

ANL-NBS-HS-000021, REV 00 35 of 131 August 2000 
Table 3 (Continued). Chemical and Isotopic Compositions of Groundwater Samples Used in This Report (data sources listed in Table 2) 
Chemical concentrations (mg L1) Isotopic analyses Calculated valuesb Fig. 2 
Well 
Namea 
Fig. 2 
sample 
No. Area pH Ca Mg Na K Cl SO4 HCO3 SiO2 
d  13C 
(per mil) 
14C activity 
(pmc) 
d  D 
(per mil) 
d  18O 
(per mil) 
log PCO2 
(atm) IAP/Kcal 
(Ca+Mg)/ (Na+K) 
(meq meq1) 
18S/50E-6dac 90 GF 8.2 23.6 11.9 102.5 13.7 20.6 106.6 230.0 80.5       0.45 
17S/50E-19aab 91 GF 8.6 7.6 8.5 252.0 27.4 69.8 175.8 415.5 42.7       0.09 
18S/50E-7aa 92 GF 8.4 25.7 9.5 140.9 19.2 37.6 147 261.2 47.5       0.31 
17S/49E-28bcd 93 AR/FMW 7.6 42.9 10.0 100.0 12.1 24.1 89.3 294.7 70.3       0.64 
18S/49E-1aba 94 AR/FMW 8.6 24.0 11.9 94.9 19.2 18.1 99.9 263.0 72.7       0.47 
18S/49E-2cbc 95 AR/FMW 7.8 28.9 11.9 120.0 9.8 19.9 74.0 352.1 58.9       0.44 
18S/49E-11bbb 96 AR/FMW 7.6 34.1 8.5 99.1 11.7 30.8 90.3 224.6 78.1       0.52 
17S/49E-29acc 97 AR/FMW 7.6 54.1 15.1 160.0 19.9 69.8 186.4 275.8 72.1       0.53 
16S/48E-8ba 98 AR 7.9 58.5 6.3 180.5 12.9 79.8 202.7 295.9 37.9       0.42 
16S/48E-7bba 99 AR 7.4 52.9 9.5 140.0 10.2 63.1 179.6 250.8 69.1       0.54 
16S/48E-7cbc 100 AR 7.7 46.9 16 130.1 9.4 62.0 179.6 239.2 64.3 6.2 31.4 102 13.1   0.62 
16S/48E-18bcc 101 AR 8.0 54.9 10.9 150.1 11.7 61.0 190.2 271.5 79.9       0.53 
16S/48E-17ccc 102 AR 7.7 66.1 10.9 169.9 12.1 83.0 235.3 239.2 77.5       0.55 
16S/48E-18dad 103 AR 7.7 52.9 8.5 149.9 10.6 63.1 187.3 236.1 76.9 5.7  104 13.6   0.49 
16S/48E-8cda 104 AR 7.6 48.1 6.8 160.0 10.2 67.0 179.6 264.2 67.9       0.41 
16S/48E-17abb 105 AR 7.4 60.1 7.8 157.0 12.1 69.1 178.7 302.0 75.1       0.51 
27N/4E-27bbb 106 AR 7.8 58.1 19.0 134.0 19.2 31.9 106.6 438.1 72.1       0.71 
NEC Well 107 AR 7.6 54.9 14.1 170.1 10.2 79.1 190.2 328.3 70.3 5.9 28.8     0.51 
DTN: See Table 2 
NOTES: adp = deep sample, sh = shallow sample, Tcp = sample from Prow Pass Tuff, Tcb = sample from Bullfrog Tuff, bh = sample from entire borehole, 95 = 
sample from 1995, v = sample from volcanic aquifer, c = sample from carbonate aquifer, Tct = sample from Tram Member or Crater Flat Tuff. Where not 
otherwise indicated, sample is from entire open interval of borehole. 
b These values are for reference only. The logarithm of carbon dioxide partial pressure (log PCO2) and the ratio of the calcium-bicarbonate ion activity 
product to the calcite equilibrium constant (IAP/Kcal) were determined using NETPATH (Plummer et al. 1994, pp. 130). Values presented for log PCO2 
and IAP/Kcal were calculated only for groundwater samples for which 14C-age corrections were made. 
cAverage value 
dThis sample also contained 8.8 mg L1 carbonate (DTN: MO0007MAJIONPH.004)

ANL-NBS-HS-000021, REV 00 36 of 131 August 2000 
INTENTIONALLY LEFT BLANK

ANL-NBS-HS-000021, REV 00 37 of 131 August 2000 
5. ASSUMPTIONS 
The analyses presented in this report sometimes required that assumptions be made concerning 
certain aspects of the hydrochemical or hydrologic system. Typically, these assumptions were 
made (1) to simplify a problem so that a solution could be approximated, (2) to obtain bounding 
estimates, or (3) because no relevant data were available at the time the analysis was made. In 
this section, these assumptions are listed along with the basis for the assumption, an indication as 
to whether or not the assumption is to be verified, where it is used in the report, and where the 
conclusions are likely to have been affected by the assumption (Table 4). 
Table 4. Assumptions Used in This Report 
Assumption Rationale for assumption TBV Section 
1 Reported chemical and isotopic data 
for pore water, perched water, and 
saturated-zone groundwater are of 
sufficient quantity and quality that 
meaningful inferences can be made 
about the hydrologic system in the 
vicinity of Yucca Mountain. 
Standard quality-control measures used by the 
laboratories producing the chemical data include 
analyses of blanks, standards, and replicates. In 
addition, the data are used in this report to define 
general qualitative trends, such that outliers, if 
present, can be distinguished from the general 
population. It is acknowledged that spatial gaps 
in the data impart uncertainties. 
No Throughout 
Secs. 6, 7, 
basis for 
conclusions 
in Sec. 7.7 
2 Water samples are representative of 
the hydrogeologic units from which 
they were collected. Mineral 
precipitation or equilibration with 
atmospheric gases at atmospheric 
pressure and temperature have not 
altered the sample water 
compositions during sampling. 
In general, water samples were collected from 
boreholes from which many borehole volumes of 
groundwater had been pumped prior to 
sampling. Only in a few cases, primarily where 
groundwater samples were bailed from 
boreholes drilled for unsaturated-zone testing 
(UZ-holes) or water-table monitoring (WT-holes), 
were the boreholes not properly developed prior 
to sampling. For many of the other boreholes, 
lithium bromide was used as a tracer during 
drilling; samples were not collected until lithium 
concentrations decreased to low levels, 
indicating that most of the drilling fluid had been 
removed. Where calcite saturation indices and 
PCO2 partial pressures were calculated, the 
groundwater samples are unsaturated with 
respect to calcite and have log PCO2 partial 
pressures greater than atmospheric log PCO2 
partial pressure (3.5), indicating calcite 
precipitation or equilibration with the atmosphere 
gases did not occur. 
No Throughout 
Secs. 6, 7 
3 It is assumed that the hydraulic 
conductivity and transmissivity of the 
volcanic rocks are isotropic and, 
thus, that flow lines can be drawn 
perpendicular to the hydraulic 
gradient. 
In spite of the likely anisotropy introduced by the 
presence of north and northwest trending faults 
in the Yucca Mountain area, this assumption was 
made to get an overall sense of the flow 
directions indicated by the hydraulic gradients. 
The likelihood that actual flow directions may be 
more aligned with fault orientations than 
indicated by these flow lines is acknowledged in 
the text. 
No Sec. 6.3, 
Fig. 4, 
affects 
conclusions 
in Sec. 7.1 
and 7.7

ANL-NBS-HS-000021, REV 00 38 of 131 August 2000 
Table 4. Assumptions Used in This Report (Continued) 
Assumption Rationale for assumption TBV Section 
4 Regional flow paths can be traced 
by linking areas with similar 
chemical and isotopic compositions 
in a downgradient direction. 
This is a purely simplifying assumption and 
clearly identified as such in the text. The 2-D 
nature of the analysis implicitly assumes the 
constancy of chemical compositions with depth 
in the water-table aquifer and ignores the 
possible chemical changes that may result from 
local recharge or vertical mixing between 
aquifers. 
No Sec. 6.5.2, 
Fig. 17, 
affects 
conclusions 
in Sec. 7.1 
5 It is assumed for the purpose of 
tracing flow lines from chemical and 
isotopic data that, once in the 
saturated-zone groundwater system, 
dD, d18O, Cl, SO4
2, Na+, and Ca2+ 
are sufficiently conservative to 
identify likely flow paths. 
This assumption is acknowledged in the text as 
an approximation. Changes in the input 
concentrations of these constituents as a result 
of climate change, or modifications to some of 
these constituents because of water/rock 
interaction, is expected to result in variability 
along a flow path in some or all of these 
constituents. However, in many cases, the areal 
contrast in concentrations between at least some 
of these constituents is large enough that 
meaningful inferences about flow directions can 
be made. 
No Secs. 6.5.2, 
6.5.5, Fig. 
17, affects 
conclusions 
in Secs. 
7.1, 7.4 
6 The 234U/238U ratio of Yucca 
Mountain recharge is elevated 
relative to the ratio in other recharge 
areas, so that elevated 234U/238U 
ratios in groundwater downgradient 
of Yucca Mountain can be used to 
identify the presence of Yucca 
Mountain recharge 
Some variability in the 234U/238U ratio of Yucca 
Mountain recharge is indicated by the differences 
in the 234U/238U ratios of perched water at 
boreholes UZ-14, WT-24, and SD-7 (Table 7). 
The lower 234U/238U ratios of perched water at 
borehole SD-7 in southern Yucca Mountain 
approaches the 234U/238U ratios of groundwater 
in the surrounding areas. The perched-water 
data from UZ-14 and WT-24 indicate that even 
under relatively high recharge conditions 
presumed to have existed during the late 
Pleistocene, some recharge had elevated 
234U/238U ratios, an argument supported by 
elevated 234U/238U ratios in groundwater at some 
downgradient boreholes. 
No Secs. 
6.5.3.1, 
6.5.7.1, 
affects 
conclusions 
in Secs. 
7.2, 7.6 
7 The offset of the dD and d18O values 
of the most isotopically depleted 
groundwater near Yucca Mountain 
from the present-day Yucca 
Mountain meteoric water line (Fig. 
21) indicates paleoclimatic effects, 
rather than evaporation or 
water/rock interaction. 
The dependence of the deuterium excess (the 
constant in the equation for the meteoric water 
line when the slope is 8) on the relative humidity 
over the moisture source area is established by 
theory (Clark and Fritz 1997, p. 45). Also, this 
assumption is supported by a correlation 
between dD and 14C (Figure 27), and between 
d18O and 14C, which shows that groundwater 
becomes more depleted with respect to dD and 
d18O with increasing 14C age. 
No Sec. 
6.5.4.1, Fig. 
21, affects 
conclusions 
in Sec. 7.3 
8 It can be assumed that groundwater 
flow to Yucca Mountain from areas 
directly north of Yucca Mountain is 
minor, particularly in areas south of 
Drillhole Wash. 
This assumption is based on the southeastward 
direction of the hydraulic gradient north of 
Drillhole Wash, and the likelihood that northwestsoutheast 
trending faults present in this area 
impart anisotropy that enhances flow along the 
trend of the faults. (See section 7.7.1). 
TBV Secs. 6.5.3, 
6.5.5.1, 
6.5.7, 
affects 
conclusions 
in 7.2, 7.4, 
7.6, 7.7.1

ANL-NBS-HS-000021, REV 00 39 of 131 August 2000 
Table 4. Assumptions Used in This Report (Continued) 
Assumption Rationale for assumption TBV Section 
9 Cl is relatively conservative in the 
groundwater system and the effects 
of water/rock interactions on this 
constituent are negligibly small. 
In the saturated zone, minerals containing Cl 
are rare in the Yucca Mountain area. 
No Secs. 6.5.2, 
6.5.5.1, 
6.5.5.2, 
Table 10, 
Fig. 24, 
affects 
conclusions 
in Secs. 
7.1, 7.4, 
7.5, Fig. 17 
10 For the purposes of modeling the 
interaction between meteoric water 
and mineral phases using 
NETPATH, the dissolved 
concentrations of Fe and Al are 
assumed to be negligibly small, such 
that these elements remain in the 
solid phases. 
Fe and Al are only sparingly soluble under 
oxidizing conditions and neutral pH, which is 
typical of groundwaters under consideration. 
No Sec. 
6.5.4.2 
11 The chemical and isotopic 
composition of the groundwater 
sample from the carbonate aquifer 
at borehole p#1 (sample p#1(c) in 
table 3) and, in particular, its Cl 
concentration, are representative of 
the composition of groundwater in 
carbonate aquifer at Yucca 
Mountain. 
Borehole p#1 is the only borehole near Yucca 
Mountain where groundwater was directly 
sampled from the carbonate aquifer, so this 
assumption is made out of necessity. The Cl 
concentration of groundwater at p#1 (0.79 mmol 
L1) is at the high end of the range of Cl 
concentrations for the carbonate aquifer 
measured at Ash Meadows (0.59 to 0.76 mmol 
L1), which may indicate the extent of the 
variability that could be expected at Yucca 
Mountain. 
No Sec. 
6.5.5.2, 
Fig. 24, 
affects 
conclusions 
in Sec. 7.4 
12 The estimated range of annual 
deposition rates for chloride at 
Yucca Mountain encompasses the 
present-day rate as well as the rates 
that prevailed when the sampled 
pore waters infiltrated below the soil 
zone. 
This assumption is supported by several 
independent lines of evidence. First, the range 
of deposition rates assumed for Yucca Mountain 
encompass the present-day rates calculated for 
sites at Red Rock Canyon and Kawich Range, 
Nevada, which represent climates that are drier 
and wetter, respectively, than that prevailing at 
Yucca Mountain today. The second line of 
evidence is the constancy of the 36Cl/Cl ratio 
throughout the Holocene, based on packrat 
midden data (Plummer et al., 1997). Finally, the 
nearly uniform Cl concentrations in the perched 
water and SZ groundwaters beneath Yucca 
Mountain also support the assumption. 
However, what is still needed is an estimate of 
the uncertainty in this deposition rate, and 
propagation of that uncertainty through the 
resulting estimates of recharge obtained by the 
chloride mass-balance method (see 
Assumption 13). 
TBV Secs. 
6.5.3.2, 
6.5.5.1, 
6.5.6, Table 
10, affects 
conclusions 
in Secs. 
7.2, 7.5, 
7.7.2

ANL-NBS-HS-000021, REV 00 40 of 131 August 2000 
Table 4. Assumptions Used in This Report (Continued) 
Assumption Rationale for assumption TBV Section 
13 The CMB method is assumed to be 
applicable to the estimation of 
recharge rates at Yucca Mountain. 
The CMB method assumes onedimensional, 
downward piston flow 
in the soil zone, no run-on or runoff, 
no Cl source other than 
precipitation, and no Cl sink (e.g., 
the formation of halite is negligible). 
The absence of chloride sources and sinks is 
indicated by the absence of halite or other Clbearing 
minerals in the soils and rocks at Yucca 
Mountain. The departures of actual flow 
conditions from the assumption of onedimensional 
piston flow are mitigated somewhat 
for calculations done on the basis of the 
saturated-zone chloride data. This is because, 
for Yucca Mountain as a whole, flow can be 
assumed to be vertical between the ground 
surface and the water table, even though lateral 
flow in the unsaturated zone could redistribute 
water on a more local scale. Similarly, when 
using the saturated-zone data with the CMB 
method, the effects of non-piston flow are 
mitigated because hydrodynamic mixing and 
mixing in the wellbore when groundwater is 
pumped tend to average the chloride 
concentrations of fast- and slow-moving water 
percolating through fractures and matrix in the 
unsaturated zone. Run-on and run-off both can 
redistribute chloride locally at Yucca Mountain. 
However, although run-on is a factor to consider 
for wells near Fortymile Wash, run-on from other 
areas to Yucca Mountain does not occur and so 
the total chloride balance for Yucca Mountain 
itself is not affected by this process. Run-off 
from Yucca Mountain to Fortymile Wash would 
tend to cause the actual chloride deposition rates 
at Yucca Mountain to be less than those 
assumed in the calculation (105 mg Cl cm2 
yr1) and thus cause the estimated Yucca 
Mountain recharge rates to overestimate the 
actual recharge. 
TBV Secs. 
6.5.3.2, 
6.5.6.1, 
Table 10, 
affects 
conclusions 
in Secs. 
7.2, 7.5 
14 The 14C activities of the carbonbearing 
phases assumed to be 
available to react with meteoric 
water in the NETPATH model 
(Plummer et al. 1994, pp. 130) are 
100 pmc for CO2 gas and 0 pmc for 
calcite and dolomite. 
The 14C activities of CO2 gas in the atmosphere 
and shallow soil zone have probably been near 
100 pmc prior to the onset of atmospheric 
nuclear weapons testing. However, the 14C 
activity of CO2 gas in the deep UZ is less than 25 
pmc, so the NETPATH model implicitly assumes 
that the water dissolved CO2 in the shallow soil 
zone. If recharge water acquired some of its 
CO2 in the deep UZ, its actual age would be less 
than the NETPATH-corrected age. Conversely, 
the NETPATH model assumes that all calcite 
and dolomite are completely depleted in 14C, a 
reasonable assumption based on measurements 
made on fracture-deposited calcite deep in the 
UZ. However, if meteoric water interacted with 
calcite in the shallow soil zone, where the 14C 
activities of calcite may be substantially nonzero, 
the actual age of the groundwater would be 
greater than the NETPATH-corrected ages. 
No Sec. 
6.5.4.2, 
Table 8, 
affects 
conclusions 
in Secs. 
7.3, 7.5

ANL-NBS-HS-000021, REV 00 41 of 131 August 2000 
Table 4. Assumptions Used in This Report (Continued) 
15 The mineral phases assumed to 
interact with meteoric water in the 
NETPATH models (Section 6.5.4.2) 
are present in the Yucca Mountain 
environment, either as primary or 
secondary minerals in the rock, or 
as windblown dust deposited at the 
ground surface. 
All minerals assumed in the NETPATH agecorrection 
models are confirmed to be present in 
the Yucca Mountain environment with the 
exception of dolomite, which is assumed to be 
available as dust deposited at the ground 
surface. This is a plausible but unconfirmed 
scenario based on the presence of dolomite 
outcrops at Bare Mountain, in the direction of the 
prevailing winds. In any case, the presence of 
dolomite is invoked to provide a source for Mg2+. 
Because most groundwaters to which the model 
was applied are low in Mg2+, very little dolomite 
is predicted to dissolve in the meteoric water and 
the corrected ages are little affected by this 
assumption. 
No Sec. 
6.5.4.2, 
Table 8, 
affects 
conclusions 
in Secs. 
7.3, 7.5 
16 The composition of meteoric water 
can be approximated as pure water 
in equilibrium with an atmospheric 
CO2 concentration of 103.5 atm with 
no other ions present in the meteoric 
water. 
This assumption implicitly ignores the 
concentration increases that all ions in the 
meteoric water undergo during 
evapotranspiration. The effect of this 
assumption is that, because evaporative 
increases in dissolved ion concentrations are 
ignored, the NETPATH age-correction models 
(Section 6.5.4.2) overestimate the amount of 
calcite and dolomite that have been dissolved 
and, hence, tend to underestimate the ages that 
would be calculated if such evaporative 
increases in concentrations had been 
considered. The effects of this assumption are 
clearly identified in the discussion of the models 
in Section 6.5.4.2. 
No Sec. 
6.5.4.2, 
Table 8, 
affects 
conclusions 
in Secs. 
7.3, 7.5 
17 Carbon isotope exchange is not a 
significant process affecting 14C 
activities of groundwater near Yucca 
Mountain. 
The NETPATH age-correction models (Section 
6.5.4.2) did not consider the process of carbonisotope 
exchange, a process that alters the 
carbon isotope composition of groundwater 
without increasing the net concentrations of 
elements contained in the carbon-bearing solid 
phases. Isotope exchange is important to 
consider where the groundwater is already 
saturated with calcite and additional interaction 
between groundwater and calcite that might alter 
the isotopic composition (14C and d13C) of the 
dissolved carbon would not be reflected by a 
change in the concentration of the total dissolved 
carbon. The groundwater in the carbonate 
aquifer is already saturated with calcite and, 
thus, exchange reactions are important to 
consider in this environment. In the volcanic 
aquifer, almost all groundwater samples for 
which calcite saturation indices have been 
calculated are undersaturated with calcite. Any 
interaction between groundwater and calcite in 
the volcanic aquifer should, therefore, be 
reflected by an increase in the dissolved carbon 
concentrations in the groundwater, a process 
already considered by the mass-balance 
approach embedded in the NETPATH modeling. 
No Sec. 
6.5.4.2, 
Table 8, 
affects 
conclusions 
in Secs. 
7.3, 7.5

ANL-NBS-HS-000021, REV 00 42 of 131 August 2000 
Table 4. Assumptions Used in This Report (Continued) 
Assumption Rationale for assumption TBV Section 
18 The chemical composition of 
groundwater at borehole J-11 is 
representative of groundwater in 
central Jackass Flats. 
Because borehole J-11 is the only borehole that 
has been drilled and sampled in central Jackass 
Flats, this is a necessary assumption. 
No Sec. 
6.5.7.2 
19 The dD and d18O compositions of 
groundwater are not substantially 
modified by water/rock interaction 
with carbonate alluvium. 
This assumption was used to infer that 
groundwater in the vicinity of the Skeleton Hills is 
groundwater from the carbonate aquifer in the 
eastern Amargosa Desert, based on their similar 
dD and d18O compositions, rather than 
chemically modified recharge from Fortymile 
Wash. It is generally accepted that the d18O 
composition of groundwater is unaffected by 
water/rock interaction at groundwater 
temperatures typical of the area and that dD 
values would be unaffected because of the trace 
levels of hydrogen in the rock (Clark and Fritz 
1997, pp. 247249). 
No Sec. 
6.5.7.2.1 
20 Groundwater near Fortymile Wash 
in the Amargosa Desert is assumed 
to have been recharged by water 
having an initial 14C activity similar to 
that at borehole a#2 (65 pmc). 
The assumption is reasonable, although difficult 
to prove, given the similarity of the environments 
and the likely cause of recharge (periodic 
channel runoff). The assumption leads to 
calculated ages between 7,000 and 15,500 years 
for groundwater in the Amargosa Desert near 
Fortymile Wash. Estimated ages based on other 
initial 14C activities are also provided in Section 
6.5.4.2. 
No Sec. 
6.5.4.2 
21 The variability in U concentrations 
and 234U/238U ratios of saturatedzone 
groundwater are attributable to 
differences in the U concentrations 
and 234U/238U ratios of recharge 
water. Once in the saturated zone, 
the U concentrations and 234U/238U 
ratios of water are unaltered by 
water/rock interaction and are 
potentially affected only by 
groundwater mixing. 
The U concentrations of groundwater in the 
immediate Yucca Mountain area do not vary 
substantially (less than a factor of 2), indicating 
that relatively little U is being added as a result of 
water/rock interaction in the saturated zone. 
Under oxidizing conditions, U seems to have 
very low affinity for sorption onto the rock as 
indicated by its low Kd values (DTN: 
LAIT831341AQ96.001, SEP Table S97026.004). 
No Sec. 
6.5.3.1, 
6.5.7.1 
22 Water coming from north or NW of 
Yucca Mountain does not have high 
234U/238U activity ratios characteristic 
of some Yucca Mountain perched 
waters. 
Data from groundwater immediately north and 
NW of Yucca Mountain are sparse, so this 
assumption is difficult to validate. However, on 
the basis of hydraulic gradients and fault 
orientations in northern Yucca Mountain, 
groundwater flow directly from the north under 
Yucca Mountain may be small (see 
Assumption 8) 
TBV Sec. 
6.5.7.1, 
affects 
conclusions 
in Sec. 7.1 
23 Chemical and isotopic data reported 
for borehole USW H-6 in USGS 
(n.d.) are representative of the 
sampled intervals and hence are 
appropriate to use to establish 
geochemical constraints on 
groundwater flow paths in the 
vicinity of Yucca Mountain. 
The data in USGS (n.d.) are all that are available 
regarding the chemical and isotopic 
compositions of groundwater from the deeper 
portion of USW H-6. However, these data are 
consistent with data from the same stratigraphic 
intervals in other boreholes in the Yucca 
Mountain vicinity. 
No Sec. 6.5.1, 
6.5.2, 6.5.4, 
6.5.5, 6.5.7 
DTN: N/A 
Note: TBV: To be verified

ANL-NBS-HS-000021, REV 00 43 of 131 August 2000 
6. ANALYSIS/MODEL 
6.1 GEOGRAPHIC AND GEOLOGIC SETTING 
Yucca Mountain is located in the Great Basin about 150 km northwest of Las Vegas, Nevada. 
The mountain consists of a series of fault-bounded blocks of ash-flow and ash-fall tuffs and a 
smaller volume of lava deposited between 14 and 11 Ma (million years before present) from a 
series of calderas located a few to several tens of kilometers to the north (Sawyer et al. 1994, 
Fig. 1). Yucca Mountain itself extends southward from the Pinnacles Ridge toward the 
Amargosa Desert, where the tuffs thin and pinch out beneath the alluvium (Figure 1). The tuffs 
dip 5 to 10 degrees to the east over most of Yucca Mountain. Crater Flat is west of Yucca 
Mountain and separated from it by Solitario Canyon, which is the surface expression of the 
Solitario Canyon Faulta steeply dipping scissors fault with down-to-the-west displacement of 
as much as 500 m in southern Yucca Mountain (Day et al. 1998, pp. 67). Underlying Crater 
Flat is a thick sequence of alluvium, lavas, and tuffs that has been locally cut by faults and 
volcanic dikes. East of Yucca Mountain, and separated from it by Fortymile Wash, is Jackass 
Flats, which is underlain by a thick sequence of alluvium and volcanic rocks. Timber Mountain, 
approximately 25 km to the north of the potential repository area, is a resurgent dome within the 
larger caldera complex that erupted the tuffs at Yucca Mountain. 
The central block of Yucca Mountain, into which waste would be emplaced if the site were 
licensed, is bounded by Drill Hole Wash on the north, the Solitario Canyon Fault on the west, the 
Bow Ridge Fault on the east, and is dissected by the Ghost Dance and Dune Wash Faults 
(Figure 2). Topography is pronounced and, north of the central block, is controlled by long, 
northwest-trending, fault-controlled washes. Within and south of the central block, washes are 
shorter and trend eastward. Topography in the southern part of Yucca Mountain is controlled by 
south-trending faults. 
6.2 HYDROGEOLOGIC SETTING 
The boundaries of the numerical model for saturated-zone flow and transport are shown in 
Figures 1 and 2, as well as on many subsequent figures. The hydrogeologic setting of the 
saturated-zone flow system in the vicinity of Yucca Mountain was summarized by Luckey et al. 
(1996, p. 13). Yucca Mountain is part of the Alkali Flat-Furnace Creek subbasin of the Death 
Valley groundwater basin, as described by Waddell (1982, pp. 1516). Discharge within the 
subbasin occurs at Alkali Flat (Franklin Lake Playa) and, possibly, Furnace Creek in Death 
Valley (Figure 1). Water inputs to the subbasin include groundwater inflow along the northern 
boundary of the subbasin, recharge from precipitation in high-elevation areas of the subbasin, 
and recharge from surface runoff in Fortymile Canyon and Fortymile Wash. North and northeast 
of Yucca Mountain, recharge from precipitation also probably occurs at Timber Mountain, 
Pahute Mesa, Rainier Mesa, and Shoshone Mountain (Luckey et al. 1996, p. 13).

ANL-NBS-HS-000021, REV 00 44 of 131 August 2000 
DTN: N/Areference only 
NOTE: The blue rectangle is the boundary of the numerical model for saturated zone flow and transport. 
Figure 1. Important Physiographic Features Near Yucca Mountain 
The saturated volcanic units at Yucca Mountain have been grouped into two confining layers and 
two aquifers by Luckey et al. (1996, pp. 1719), based on similarity in their core-scale 
hydrologic and mechanical properties (Figure 3). In general, the confining units are zeolitic, 
nonwelded tuffs, and the uppermost aquifers are fractured, welded and devitrified tuffs (the 
Upper Volcanic Aquifer) or include intervals of fractured, welded and devitrified tuffs (the 
Lower Volcanic Aquifer). Most zeolite development took place before approximately 11 Ma 
(Broxton et al. 1987, p. 101; Bish 1989, pp. 31, 33) and was concentrated in the originally 
permeable, nonwelded vitric tuffs; development was less intense in the partly to densely welded, 
devitrified tuffs that are present in the interiors of the Prow Pass and Bullfrog Tuffs of the Crater 
Flat Group. Additionally, alteration to zeolites and clays was more intense and zeolite facies 
were displaced upward in northern Yucca Mountain because of the high paleotemperature 
gradients that existed near the calderas (Broxton et al. 1987, pp. 107108; Bish 1989, p. 35). 
510000.00 530000.00 550000.00 570000.00 
4030000.00 
4040000.00 
4050000.00 
4060000.00 
4070000.00 
4080000.00 
4090000.00 
4100000.00 
4110000.00 
Yucca Flat 
Pahute Mesa 
Jackass 
Flats Crater 
Flat 
Calico 
Hills 
Striped 
Hills 
Skeleton 
Hills 
Amargosa Desert 
Rock Valley 
Skull 
Mountain 
Oasis Valley 
Yucca Mountain 
Amargosa River 
Fortymile Wash 
Sarcobatus 
Flat
Bullfrog Hills 
Buckboard 
Mesa 
Bar 
e Mountain 
BeattyWash 
Timber 
Mountain 
Rainer 
Mesa
Eleana Range 
Shoshone 
Mountain 
Fort 
ymile 
Canyon 
Funeral Mountains 
Specter Range 
Ash Meadows 
L. Skull 
Mountain 
Amargosa 
Flat 
Death Valley 
Mine Mountain 
Franklin Lake 
Playa 
UTM-X (meters) 
UTM-Y (meters) 
Solitario Canyon 
Furnace Creek 
Pinnacles Ridge 
Amargosa Valley 
(formerly Lathrop Wells) 
Site-Model Boundary

ANL-NBS-HS-000021, REV 00 45 of 131 August 2000 
Regionally, argillite of the Eleana Formation is a confining layer, and the Paleozoic carbonate 
rocks are an important aquifer (Winograd and Thordarson 1975, Table 1; Laczniak et al. 1996, 
Table 1). The Eleana Formation was not intersected by the one borehole drilled deep enough to 
penetrate it at Yucca Mountain but has been inferred to be present in northern Yucca Mountain 
based on areal magnetic data (Luckey et al. 1996, p. 20). The carbonate aquifer was penetrated 
at borehole p#1 (the correspondence between well identifiers and borehole abbreviations is given 
in Table 2), but its continuity and thickness in this part of southern Nevada, and consequently, its 
importance as a regional aquifer, may be less near Yucca Mountain than in areas farther to the 
east (Thomas et al. 1996, Fig. 17). 
Average hydraulic conductivities of the hydrogeologic units present at Yucca Mountain were 
calculated based on single-borehole aquifer-test data summarized in Luckey et al. (1996, 
Table 4) and are listed in Table 5. Flow logs reported in Luckey et al. (1996, pp. 3739) indicate 
that most of the flow in the lower volcanic aquifer is produced by the Prow Pass and Bullfrog 
Tuffs, with generally lesser amounts produced by other formations. Flow logs for other 
boreholes (Benson et al. 1983, Figs. 46) indicate that variable amounts of water are produced 
from other formations. The percentages of water contributed to water samples by individual 
formations based on flow logs conducted during pumping were determined as part of the present 
analysis and are listed for wells near Yucca Mountain in Table 6. 
Water production from boreholes in the northern Amargosa Desert is generally from valley-fill 
deposits, with the exceptions of the CIND-R-LITE borehole in which production is from the 
upper volcanic aquifer and borehole TW-5 in which production is from the lower carbonate 
aquifer (Czarnecki et al. 1997, Fig. 8). The distribution of the different types of valley-fill 
deposits in the Amargosa Desert is shown by Kilroy (1991, Fig. 3) and includes channel and 
playa sediments of Holocene age, alluvial fan and freshwater carbonate deposits of Quaternary 
age, and conglomerates of Tertiary age. Within the model boundary area of Figure 1, 
Precambrian and Paleozoic clastic and carbonate rocks crop out in the Striped Hills and Skeleton 
Hills (Claassen 1985, Fig. 1). Alluvium directly south of Yucca Mountain and along the 
Fortymile Wash drainage is predominantly derived from volcanic rocks, whereas alluvium near 
Bare Mountain and near the southeast and southwest corners of the model area is predominantly 
derived from carbonate rocks (Claassen 1985, Fig. 1). Alluvium of mixed lithology is present 
between these areas. The hydraulic conductivity of the valley fill in the Amargosa Desert is 
poorly known; Winograd and Thordarson (1975, p. C37, Table 3) reported that valley fill on the 
NTS had a transmissibility that ranged from 800 to 33,500 gal d1 ft1, based on the results of 
pump tests from six boreholes. The saturated hydraulic conductivities calculated by dividing the 
transmissibilities by the saturated thickness at these boreholes range from 5 to 70 gal d1 ft2 (0.2 
to 2.9 m d1).

ANL-NBS-HS-000021, REV 00 46 of 131 August 2000 
Figure 2. Locations of Boreholes in the Vicinity of Yucca Mountain 
and the Northern Amargosa Desert (continued on next page) 
525000.00 535000.00 545000.00 555000.00 565000.00 
4030000.00 
4040000.00 
4050000.00 
4060000.00 
4070000.00 
4080000.00 
4090000.00 
4100000.00 
UTM-X (meters) 
UTM-Y (meters) 
Bare 
Mountain FaultGravity Fault 
Specter Range 
Thrust Fault 
Highway 95 Fault 
Fortymile Wash 
Amargosa River 
Paintbrush Canyon Fault 
BowRidge 
Fault 
Windy WashFault 
Solitario Canyon Fault 
Crater Flat Fault 
Dune Wash Fault 
Highway 95 
Site-Model 
Boundary 
94 
96 
95 
93 97 
76 
106 
90 
92 
75 
91 
89 
74 
73 
69 68 
67 72 
85 
86 87 
88 
70 
66 
65 63
62 
51 71 
61 64 
83 
82 
84 58 
57
53 
60 
59 
77 
78 
79 
80 
98 99 
100 
101 
102 103 104 
105 
107 
81 
54 
56
52 
55 
39 38 
43 40 
41 
42 
36 
35 
34 
27 
46 
47 
50 49 
45 
48 
44 
37 
33 
3
5 
4
7 
6 
1,2 
8 
9,10 
11,12 
13,14 
30,31,32 
28 29 
20,21 
15-18 26 
24 19 
22 
23 
25
Ghost Dance Fault 
DHW

ANL-NBS-HS-000021, REV 00 47 of 131 August 2000 
DTN: GS991208314221.001 (fault locations); MO9907YMP99025.001 and 
GS920508312321.004 (borehole coordinates) 
NOTES: See Table 2 for well identifiers 
DHW = Drill Hole Wash 
Well groupings are discussed in Section 6.5.1. 
The figure has color-coded data points and should not be read in a black and white version. 
Figure 2 (Continued). Locations of Boreholes in the Vicinity 
of Yucca Mountain and the Northern Amargosa Desert 
Fortymile Wash - North (FMW-N) 
Yucca Mountain - North (YM-N) 
Yucca Mountain - East (YM-E) 
Yucca Mountain - Central (YM-C) 
Yucca Mountain - South (YM-S) 
Crater Flat (CF) 
Nye County EWDP (NC-EWDP) 
Jackass Flats (JF) 
Lathrop Wells (LW) 
Fortymile Wash - South (FMW-S) 
Fortymile Wash - East (FMW-E) 
Fortymile Wash - West (FMW-W) 
Skeleton Hills (SH) 
Gravity Fault (GF) 
Amargosa River/Fortymile Wash (AR/FMW) 
Amargosa River (AR) 
Sub-areas

ANL-NBS-HS-000021, REV 00 48 of 131 August 2000 
DTN: N/A-reference only; Source: Luckey et al. (1996), Fig. 7 
NOTE: The explanations for the symbols for the geologic units are given in a footnote to Table 2. 
Figure 3. Selected Geologic and Hydrogeologic Units for the Saturated Zone at Yucca Mountain 
Table 5. Hydraulic Conductivities of Hydrogeologic Units 
Hydraulic Conductivity 
Hydrogeologic 
Unit 
Range 
(m d1) 
Geometric Mean 
(m d1) 
Arithmetic Mean 
(m d1) 
Number of 
Measurements 
Upper Volcanic Aquifer 1.0   1 
Upper Volcanic 
Confining Unit 
2.0 x 102 to 
2.6 x 101 
8.5 x 102 1.3 x 101 3 
Lower Volcanic Aquifer < 3.7 x 103 to 1.4 1.4 x 101 4.3 x 101 10 
Lower Volcanic 
Confining Unit 
5.5 x 106 to 
1.1 x 101 
9.1x104 1.7x102 7 
Carbonate Aquifer 1.9 x 101   1 
DTN: N/A-reference only; Source: Luckey et al. (1996), Table 4 
Crater 
Flat 
Group 
Selected Geologic Units 
Paintbrush 
Group
Topopah Spring Tuff 
(Tpt) 
Calico Hills Formation (Tac) 
Prow Pass Tuff (Tcp) 
Bull Frog Tuff (Tcb) 
Tram Tuff (Tct) 
Flow Breccia and Lava 
Lithic Ridge Tuff (Tlr) 
Older Tuffs, Lavas, 
and Breccias 
Lower Volcanic Aquifer 
Upper Volcanic Confining Unit 
Upper Volcanic Aquifer 
Lower Volcanic 
Confining Unit 
Eleana Formation 
Cambrian to 
Devonian Formations 
Proterozoic Rocks 
Upper Clastic 
Confining Unit 
Lower Carbonate 
Aquifer 
Proterozoic 
Confining Unit 
Saturated-Zone 
Hydrogeologic 
Units 
Depths of pre-Tertiary 
units are variable or uncertain ? ? 
1000 
2000
?
?
? 
Typical Depths (m) 
0
?

ANL-NBS-HS-000021, REV 00 49 of 131 August 2000 
Table 6. Percentage of Water Contributed to Water Samples by Individual Formations 
Lower Vol. 
Confining 
Unit Lower Volcanic Aquifer 
Upper Vol. 
Confining 
Unit 
Upper 
Volcanic 
Aquifer 
Sample 
% Lithic 
Ridge Tuff 
and older 
tuffs 
% Tram 
Tuff of 
Crater Flat 
Group 
% Bullfrog 
Tuff of 
Crater Flat 
Group 
% Prow Pass 
Tuff of Crater 
Flat Group 
% Calico 
Hills 
Formation 
% Topopah 
Spring Tuff 
J-12     0.0 100.0 
J-13 0.0 5.0 0.0 0.0 0.0 95.0a 
JF#3      100.0 
WT#14     0.0 100.0b 
WT#15      100.0 
G-2 0.0 0.0 0.0 0.0 100.0  
UZ-14 (Tcp)   0.0 100.0c 0.0  
UZ-14 (Tcb)   100.0c 0.0 0.0  
H-1 (Tcp) 0.0 0.0 0.0 100.0 0.0  
H-1 (Tcb) 0.0 0.0 92.0 8.0 0.0  
b#1 (bh)  0.0 49.0 19.0 32.0  
b#1 (Tcb)  0.0 100.0 0.0 0.0  
c#1  36.0 64.0 0.0 0.0  
c#2  0.0 93.0 7.0 0.0  
c#3  25.0 75.0 0.0 0.0  
c#3 ('95)  25.0 75.0 0.0 0.0  
p#1(v) 35.0 0.5 4.5 58.0 2.0  
G-4  98.5 1.0 0.5   
H-3 10.0 90.0     
H-4 12.5 32.0 36.5 19.0   
H-5  11.0 89.0    
UZ#16    100.0   
ONC#1     0.0 100.0 
WT#12      100.0b 
WT-17    100.0   
WT#3   100.0    
H-6(bh) 0.0 34.0 66.0 0.0   
H-6(Tct) 0.0 100.0 0.0 0.0   
H-6(Tcb) 0.0 0.0 100.0 0.0   
WT-7     0.0 100.0b 
WT-10      100.0 
DTN: GS920408312321.002; Sources: Luckey et al. (1996, pp. 3739); Benson et al. (1983, Figs. 46); Thordarson (1983, p. 50). 
NOTES: aAlthough borehole J-13 is a deep borehole that extends into the Lithic Ridge Tuff, Thordarson (1983, p. 50) estimated 
that 95% of the J-13 water sample used in this report originated from the Topopah Spring Tuff between depths of 282.7 to 
422.5 m. This estimate was presumably based on the distribution of transmissivity in the borehole, as determined from 
hydraulic tests in which packers isolated discrete intervals. The transmissivity of the interval of the Topopah Spring Tuff 
between 282.7 to 422.5 m was 120 m2 d1, whereas the total transmissivity for the remainder of the borehole was about 
5% of this value (Thordarson 1983, p. 55). 
bIndicates the open, saturated interval of the borehole was in the Topopah Spring Tuff and Calico Hills Formation. The 
water may have come from anywhere within this interval. 
cBailed sample from open borehole (DTN: GS980908312322.008).

ANL-NBS-HS-000021, REV 00 50 of 131 August 2000 
6.3 POTENTIOMETRIC SURFACE 
A map of the potentiometric surface in the Yucca Mountain area was developed as part of an 
associated AMR (USGS 2000, Fig. 1-2) based on average water-level data collected from 1985 
to 1995 (Figure 4). The potentiometric-surface elevations at individual boreholes are based on 
composite water levels in the volcanic units, or at boreholes where heads were measured at 
multiple depths in the units, on the shallowest head measurement. The water levels have been 
influenced by local pumping in the southern part of the model area (USGS 2000, p. 4). 
Water potential elevations are about 1,030 m at the northern end of the mountain, 810 m at 
borehole VH-2 in Crater Flat, 730 m beneath much of central Yucca Mountain, and 728 m 
beneath Fortymile Wash (Tucci and Burkhardt 1995, Fig. 4). The potentiometric heads in the 
lower monitored intervals of the volcanic units were higher than 775 m at boreholes H-1, H-5, 
and H-6 and 756.8 m at borehole H-3 (Tucci and Burkhardt 1995, Table 2). The potentiometric 
head in the carbonate aquifer at p#1 was 752.4 m, indicating that an upward head gradient exists 
between the carbonate aquifer and the lower volcanic aquifer in this part of Yucca Mountain. In 
the small-gradient area east and southeast of Yucca Mountain, where the potentiometric surface 
elevations are between 728 to 732 m, the hydraulic gradient ranges from 0.0001 to 0.0004 (Tucci 
and Burkhardt 1995, p. 9). 
The moderate hydraulic gradient (0.02 to 0.04) (Tucci and Burkhardt 1995, p. 9) across the 
western boundary of Yucca Mountain was attributed by Luckey et al. (1996, p. 25) to the 
possible presence of low-permeability fault gouge in the Solitario Canyon Fault or to the 
juxtaposition of transmissive formations in the hanging block of the fault against less 
transmissive formations in the footwall side of the fault. An additional but related explanation 
may be that, as a result of the down-to-the-west displacement in the southern part of Yucca 
Mountain, the most transmissive parts of the lower volcanic aquifer are locally above the water 
table immediately east of the Solitario Canyon Fault. The transmissivities of the lower volcanic 
aquifer at boreholes H-3 and H-5 are < 1.1 m2 d1 and 35 m2 d1, values that are low compared to 
the transmissivities of boreholes east of Yucca Mountain Crest, such as H-4 (178 m2 d1) and 
G-4 (589 m2 d1) (Luckey et al. 1996, Table 5). The very low transmissivity measured at 
borehole H-3 may be the result of the near-complete desaturation of the Bullfrog Tuff at this 
location, whereas the much larger transmissivity at borehole H-5 may be the result of the nearcomplete 
saturation of the Bullfrog Tuff. 
The cause, and even the existence, of the large hydraulic gradient (0.11) in the northern part of 
Yucca Mountain have been the subject of considerable debate, as summarized by Luckey et al. 
(1996, pp. 21, 24, 25). The possible causes include: (1) flow across the thick upper volcanic 
confining unit; (2) a smaller than average hydraulic conductivity in the lower volcanic aquifer 
resulting from a combination of hydrothermal alteration and lithostatic pressure; (3) an artifact of 
attempting to contour heads in two distinct aquifers, the upper and lower volcanic aquifers, 
separated by a thick confining unit; (4) a graben-bounding fault that drains water from the 
volcanic aquifer into the carbonate aquifer beneath northern Yucca Mountain, decreasing flow in 
the volcanic aquifer south of the fault; (5) a graben-bounding fault marks the effective northern 
limit of the lower volcanic aquifer, due to thinning and alteration of the tuffs of the Crater Flat

ANL-NBS-HS-000021, REV 00 51 of 131 August 2000 
DTN: GS991208314221.001 (Tertiary faults); Source: USGS (2000, Fig. 1-2) 
NOTE: The inferred groundwater flow paths are based on Assumption 3 in Table 4. 
Figure 4. Potentiometric Surface and Inferred Flow Paths (Blue Lines) for Yucca Mountain and Vicinity

ANL-NBS-HS-000021, REV 00 52 of 131 August 2000 
Group north of the fault; and (6) the upper clastic confining unit, the Eleana Formation, is buried 
beneath northern Yucca Mountain and blocks groundwater flow toward the south. Another 
explanation, not cited by Luckey et al. (1996), is that the potentiometric surface is simply 
reflecting the large change in ground-surface elevation in the northern part of the Site-Model area. 
Explanations 4 through 6 rely extensively on interpretations of magnetic and gravity data. There 
is no direct surface expression of the postulated graben-bounding fault, nor is there direct 
evidence from boreholes or outcrop that the Eleana Formation is present in northern Yucca 
Mountain. However, the transmissivity of the lower volcanic aquifer would be expected to 
decrease north of Yucca Mountain because of the thinning and disappearance of Bullfrog and 
Prow Pass Tuffs in the Pinnacles Ridge area (Carr et al. 1986, Figs. 14 and 15). In this case, 
decreases in head might accompany the increases in transmissivity that result from the greater 
thicknesses of these units toward the south. 
Flow logs for borehole G-2 (Luckey et al. 1996, Fig. 15) provide evidence that the 
transmissivities of the Bullfrog and Prow Pass Tuffs may be less in the northern part of Yucca 
Mountain compared to areas further south. These logs show that water inflow during pumping 
was restricted to the upper volcanic confining unit (the Calico Hills Formation) at this borehole. 
Pump tests conducted at borehole G-2 in the Calico Hills Formation resulted in an estimated 
mean transmissivity of 9.4 m2 d1 (OBrien 1998, p. 21); however, the natural, predrilling 
transmissivity at borehole G-2 is probably even less than this value because the Calico Hills 
Formation may have been hydrofractured by excess downhole fluid pressure applied during 
drilling (Stock et al. 1985, p. 8691). 
Several possible flow paths were defined by drawing flow lines perpendicular to the gradient in 
the potentiometric surface (Figure 4). The flow paths were drawn under the assumption that 
hydraulic conductivity and transmissivity are isotropic (Assumption 3 in Table 4). In fracturedrock 
aquifers, such as those at Yucca Mountain, hydraulic conductivity probably is anisotropic 
(Luckey et al. 1996, p. 36). However, Czarnecki and Waddell (1984, pp. 2728 and Table 4) 
reported that their subregional model duplicated measured water levels more accurately when the 
aquifer was simulated as isotropic rather than anisotropic. Therefore, this assumption provides a 
reasonable basis for evaluating the possible sources and destinations of groundwater in the 
Yucca Mountain area. Groundwater models of the site that account for the effects of faults and 
anisotropy on the flow paths may indicate paths substantially different than those drawn in 
Figure 4. 
The flow paths shown in Figure 4 indicate that water may flow under Yucca Mountain 
predominantly from the northwest. In Figure 4, some of the flow from the north is predicted to 
be diverted southeastward toward Fortymile Wash in northern Yucca Mountain, an area 
dominated by northwest-trending, fault-controlled washes. The inferred flow lines indicate that 
groundwater flows southeast from Yucca Mountain and southwest from Jackass Flats toward the 
Fortymile Wash area. Groundwater from the Fortymile Canyon area flows south and then 
southwest in the southern part of the Site-Model Area. Flow in the southern part of Yucca 
Mountain is predominantly southeastward toward Fortymile Wash rather than south toward the 
Amargosa Desert (Figure 4). The faults in the southern part of Yucca Mountain do not seem to 
exert an observable effect on the potentiometric surface, but this lack of evidence could simply 
be due to the sparseness of boreholes and shallowness of the hydraulic gradient in this area.

ANL-NBS-HS-000021, REV 00 53 of 131 August 2000 
6.4 PREVIOUS WORK 
Yucca Mountain has been under investigation as a potential repository site since the early 1980s, 
and an extensive body of literature exists concerning its hydrologic and geologic characteristics. 
The following summary of that literature is not exhaustive but represents the range of 
interpretations that have been made concerning groundwater flow at and near Yucca Mountain. 
6.4.1 Data Sources 
Many of the geochemical and isotopic data for Yucca Mountain discussed in this report were 
first presented in Benson et al. (1983, Table 1), Ogard and Kerrisk (1984, Tables I, II, V, and 
VI), and Benson and McKinley (1985, Table 1). Benson et al. (1983, Figs. 4, 5, and 6) also 
provided data on the depths of water-producing zones in the wells that produced the groundwater 
samples. Additional hydrochemical and isotopic data from the regional groundwater system 
were obtained from relatively shallow wells drilled to monitor water table depths and from 
unsaturated-zone test wells that reached the water table. 
Benson et al. (1983, p. 16) and Luckey et al. (1996, p. 43) cautioned that the high lithium 
concentrations and the presence of foam in some of the groundwater samples indicated that these 
samples contained air-foam drilling fluids to which lithium bromide had been added as a tracer. 
These comments referred primarily to samples collected at water-table (WT) boreholes but may 
also apply to samples collected at unsaturated-zone test holes that reached the water table. Based 
on the lithium concentrations of the water samples, Benson et al. (1983, p. 16) estimated that the 
percentage of drilling fluid in the samples was generally much less than 1%; however, lithium 
readily sorbs to rock, so the lithium concentrations may be an unreliable indicator of remnant 
drilling fluid in the samples (see Assumption 2 in Table 4). 
Pore- and perched-water data from the unsaturated zone at Yucca Mountain were reported by 
Yang et al. (1996, Tables 24, 6, 7) and Yang et al. (1998, Tables 24, 6, 913, 1517). Milne et 
al. (1987, Tables 3 and 5) and Ingraham et al. (1991, Tables 1 and 2) discussed delta deuterium 
(dD) and delta oxygen-18 (d18O) values of modern precipitation in southern Nevada. 
Hydrochemical and isotopic data for the Amargosa Desert were reported by Claassen (1985, 
Tables 1 and 6) and by McKinley et al. (1991, Table 2). Additional hydrochemical data for 
much of the NTS were summarized in McKinley et al. (1991, Table 6), data for the Death Valley 
Region were summarized by Perfect et al. (1995, attached dataedit.exe data file), and data for 
Nye County were compiled by Oliver and Root (1997, attached yucca.xls data file). 
6.4.2 Interpretations of Flow Patterns in the Vicinity of Yucca Mountain from 
Hydrochemical and Isotopic Data 
Over the past ten years, several published studies (White and Chuma 1987; Benson and Klieforth 
1989; Stuckless et al. 1991; Fridrich et al. 1994; Luckey et al. 1996; Campana and Byer 1996) 
have focused on the origin and flow paths of groundwater in the vicinity of Yucca Mountain. 
These authors primarily differed with respect to the extent of recharge occurring through Yucca 
Mountain or along Fortymile Wash, the residence time of groundwater beneath Yucca Mountain, 
and the extent of mixing between the volcanic and carbonate aquifers.

ANL-NBS-HS-000021, REV 00 54 of 131 August 2000 
Based on dD and d18O data for the Yucca Mountain region, Benson and Klieforth (1989, p. 48) 
proposed that groundwater beneath Yucca Mountain could be a mixture of overland flow along 
Fortymile Wash and groundwater flow from upland areas to the north (Pahute Mesa). Benson and 
Klieforth (1989, pp. 4849, Fig.11) reported that the d18O values of groundwater in the vicinity of 
Yucca Mountain were higher for water with apparent 14C ages between 18.5 and 9 ka (thousand 
years before present) and were lower and constant since then, a relation that was attributed to 
global climate change and accompanying changes in the paths of storms bringing moisture to 
southern Nevada prior to 9 ka. Benson and Klieforth (1989, p. 42) also argued that groundwater 
14C ages in the Yucca Mountain area do not require substantial correction to account for the 
dissolution of calcite, based on geochemical modeling of three wells in Fortymile Wash by White 
and Chuma (1987, Table 2, Fig. 23) and the observation that surface runoff in Fortymile Wash 
was saturated with calcite and yet still had a 14C activity of 100 percent modern carbon (pmc). 
Groundwater in the volcanic aquifers in the Yucca Mountain area was interpreted by Stuckless et 
al. (1991, p. 1414) to be a mixture of at least three end members. One source of groundwater in 
the volcanic aquifer, represented by groundwater from borehole UE-29 a#2 in Fortymile Canyon, 
is characterized by isotopically light carbon-13 (d13C), a high carbon-14 (14C) activity, and 
isotopically heavy dD. This groundwater is either mixed with groundwater from the Paleozoic 
carbonate aquifer having an isotopically heavy d13C and a low 14C activity, or alternatively, is 
modified by calcite derived from the carbonate aquifer with these isotopic characteristics. A 
third, poorly constrained end member with a d13C value and 14C activity intermediate between 
that of the first and second sources and having a lighter dD value than the first source was 
hypothesized to explain the scatter in the d13C and 14C about a possible mixing trend line 
(Stuckless et al. 1991, Fig. 4). Groundwater at Pahute Mesa from borehole UE-20 a#2 has these 
characteristics and was suggested by Stuckless et al. (1991, p. 1414) as a possible third source 
for the groundwater at Yucca Mountain. 
Fridrich et al. (1994, pp. 153159) used the spatial variability in d13C, water-table temperature, 
magnetic data, and unsaturated-zone heat flux to infer that groundwater in the northern part of 
Yucca Mountain entered the deep carbonate aquifer and reemerged into the shallow volcanic 
aquifer along faults in the central and southern parts of the mountain. Luckey et al. (1996, p. 44) 
noted the downgradient increase in the calcium-to-sodium ratio from west to east across Yucca 
Mountain and speculated that it might reflect either upwelling from the underlying carbonate 
aquifer through faults on the east side of Yucca Mountain or mixing of water flowing from the 
west with calcium-rich water recharged from Fortymile Wash. 
Campana and Byer (1996, p. 465) presented a steady-state mixing-cell model of the NTS 
regional groundwater flow system that used corrected 14C ages to determine flow volumes and 
directions and recharge rates in the regional flow system. Their results indicated that between 28 
and 88% of the groundwater beneath Yucca Mountain originated as local recharge, which was 
estimated to be between 1.9 to 4.2 mm yr1 as an annual average distributed evenly across the 
cells surface area (Campana and Byer 1996, p. 473). In their model, the remainder of the flow 
beneath Yucca Mountain originated from the west in Crater Flat. Flow from upland areas north 
of Yucca Mountain was diverted eastward toward Fortymile Canyon and Fortymile Wash before 
reaching Yucca Mountain. Groundwater beneath Yucca Mountain was interpreted by Campana 
and Byer (1996, Fig. 5) to be a mixture of groundwaters having different 14C activities, with a

ANL-NBS-HS-000021, REV 00 55 of 131 August 2000 
mean age of 10.9 to 16.0 ka and a median age of 6.3 to 6.5 ka (Campana and Byer 1996, Table 
7). Approximately 20 to 25% of the total recharge in their regional model domain originated 
from the Fortymile Canyon and Wash area, where areally distributed recharge rates were 
estimated to be 26 to 32 mm yr1 (5.3 x 106 to 6.6 x 106 m3 yr1) (Campana and Byer 1996, 
p. 476). Water in the Amargosa Desert originated from groundwater flow from Fortymile 
Canyon and Wash area and Crater Flat. 
6.4.3 Origin of Water in the Amargosa Desert 
Winograd and Thordarson (1975, p. C111) concluded from chemical data that groundwater in 
the central Amargosa Desert (Figure 1) originates from at least three sources: (1) water 
dominated by calcium, magnesium, sodium, and bicarbonate that flows across the hydraulic 
barrier responsible for springs at Ash Meadows; (2) water southwest of Amargosa Valley 
(formerly, Lathrop Wells) dominated by sodium, potassium, and bicarbonate that probably flows 
from western Jackass Flats; and (3) water in the west-central and northwestern Amargosa Desert 
that flows from Oasis Valley. In addition, Winograd and Thordarson (1975, p. C112) noted the 
dilute nature of the groundwater near Fortymile Wash and interpreted the low dissolved solids 
content of this water to indicate an origin from paleorecharge along the channel rather than 
underflow from areas north of Jackass Flats. Winograd and Thordarson (1975, p. C112) also 
noted the higher dissolved solids content in wells at and south of Amargosa Valley, which they 
attributed to small amounts of groundwater leaking upward from the carbonate aquifer into the 
valley fill near the Gravity Fault. 
Claassen (1985) and White and Chuma (1987) presented different hypotheses regarding the 
origin of water in the northern Amargosa Desert near the present-day Fortymile Wash drainage. 
Claassen (1985, p. F30) argued that groundwater near surface drainages was predominantly 
derived from surface runoff during the Pleistocene and the very early Holocene based on its 
apparent 14C age (Claassen 1985, Fig. 15) and on the high ratio of calcium plus magnesium to 
sodium plus potassium [(Ca2+ + Mg2+)/(Na+ + K+)] of groundwater from the northern Amargosa 
Desert compared to groundwater from upgradient locations (Claassen 1985, p. F13, Fig. 9). In 
contrast, White and Chuma (1987, p. 578) argued that groundwater in the northern Amargosa 
Desert evolved chemically from groundwater that had recharged upgradient in Fortymile 
Canyon. The 14C age of groundwater in the northern Amargosa was used to calculate 
groundwater velocities beneath Fortymile Wash of between 3 and 30 m yr1 over an average 
distance of about 15 km extending southward from borehole J-13 to the north-central Amargosa 
Desert (White and Chuma 1987, p. 578). 
6.4.4 Numerical Flow Models 
Numerical models of flow in the Yucca Mountain region include those by Czarnecki and 
Waddell (1984, Plate 2) and Czarnecki (1984, p. 1). In the models of Czarnecki and Waddell 
(1984, Plate 2) and Czarnecki (1984, Fig. 14), groundwater recharged in Fortymile Canyon 
flowed around a low-permeability barrier (assumed to cause the large hydraulic gradient in the 
northern part of Yucca Mountain) and under Yucca Mountain from the west and northwest. 
From the potential repository area of Yucca Mountain, groundwater flowed south-southeast and 
then southwest into the northern Amargosa Desert. Czarnecki and Waddell (1984, p.12 (model 
variable Qfm) and p. 20) estimated recharge beneath Fortymile Wash and Canyon to be 2.2 x 104 
m3 d1 (8.0 x 106 m3 yr1) based on a trial-and-error fit of the model to measured water-level data.

ANL-NBS-HS-000021, REV 00 56 of 131 August 2000 
This volume of water corresponded to an average recharge rate of 41 mm yr1 for the model area 
corresponding to Fortymile Wash and Canyon (Czarnecki 1984, p. 5). Czarnecki (1984, p. 18) 
used the same recharge rate for the Fortymile Wash and Canyon area in his model and assumed 
an areally distributed recharge rate of 0.5 to 2.0 mm yr1 in the vicinity of Yucca Mountain. 
Sensitivity analyses by Czarnecki (1984, p. 21) investigated the possible effects of increased 
recharge rates that might occur under a wetter climate with twice the annual precipitation of the 
present climate. These analyses indicated that a 130-m water-table rise and an increase in 
groundwater flux by a factor of 2 to 4 could be expected beneath the potential repository area 
during such a climate (Czarnecki 1984, p. 32). Flow directions simulated for the wetter climate 
were similar to those simulated for the present climate (Czarnecki 1984, Figs. 14 and 15). 
However, this conclusion may have resulted from the two-dimensional nature of the model and 
the model assumptions regarding the cause of the large hydraulic gradient in the northern part of 
Yucca Mountain. 
DAgnese et al. (1997, Figs. 1 and 32) presented a model of flow in the Death Valley region that 
included Yucca Mountain; however, because of its very large areal extent, the model lacks the 
detail near Yucca Mountain provided by the earlier models. Generalized flow vectors based on 
the model show groundwater from the north flowing west of Yucca Mountain beneath Crater 
Flat and east of Yucca Mountain beneath Fortymile Canyon (DAgnese et al. 1997, Fig. 32). 
6.4.5 Fortymile Wash Recharge 
In addition to the recharge estimates for Fortymile Wash made by Czarnecki and Waddell (1984, 
p. 12) through numerical flow modeling (8.1 x 106 m3 yr1) (Section 6.4.4) and by Campana and 
Byer (1996, p. 476) through hydrochemical mixing models (5.3 x 106 to 6.6 x 106 m3 yr1) 
(Section 6.4.2), recharge estimates for various reaches of Fortymile Wash were also made by 
Savard (1998, p. 20) based on channel-volume losses during runoff and an assumed inversely 
proportional relationship between these volume losses and recharge. Long-term groundwater 
recharge rates were 27,000 m3 yr1 for Fortymile Canyon, 1,100 m3 yr1 for upper Jackass Flats, 
16,400 m3 yr1 for lower Jackass Flats, and 64,300 m3 yr1 for the Amargosa Desert (Savard 
1998, p. 1). Adding these values, the total recharge estimated for Fortymile Canyon and 
Fortymile Wash by Savard (1998) is 1.1 x 105 m3 yr1, or 1.3% of the 8.1 x 106 m3 yr1 used in 
the models of Czarnecki and Waddell (1984, p. 12) and Czarnecki (1984, p. 18), or about 0.6 
mm yr1, assuming the same area for Fortymile Canyon and Wash that was used in those models. 
6.5 ANALYSIS OF HYDROCHEMICAL AND ISOTOPIC DATA 
This section presents the results of the analysis of the hydrochemical and isotopic data in the 
vicinity of Yucca Mountain in seven major subsections. Subsection 6.5.1 presents areal 
distribution maps showing values measured for chemical and isotopic constituents in 
groundwater samples from wells in the vicinity of Yucca Mountain (data for these plots are 
listed in Table 3). Subsection 6.5.2 presents an analysis of groundwater flow paths in the Yucca 
Mountain region based on these distribution maps. Subsection 6.5.3 presents an evaluation of 
the evidence regarding local recharge at Yucca Mountain. An evaluation of the evidence for the 
timing of recharge is presented in Subection 6.5.4. Evidence for mixing relations among 
groundwaters is discussed in Subection 6.5.5. Section 6.5.6 reviews geochemical and isotopic 
evidence for the magnitude of recharge at Yucca Mountain. Evidence for downgradient dilution 
of chemical constituents in groundwaters from Yucca Mountain is evaluated in Subection 6.5.7.

ANL-NBS-HS-000021, REV 00 57 of 131 August 2000 
6.5.1 Areal Distributions of Chemical and Isotopic Species 
In this subsection, areal distributions of values measured for the concentrations of major cations 
and anions and for isotopic ratios are presented, along with some preliminary analysis. The 
discussions of areal trends in individual chemical and isotopic constituents are intended to be 
somewhat general in character. 
The locations of wells cited in this section are shown in Figure 2. As the figure shows, areal 
coverage is somewhat uneven, with many wells located at Yucca Mountain and in agricultural 
areas in the Amargosa Desert but with far fewer wells elsewhere in the map area. Data are 
particularly scarce in the eastern and northern parts of the map area and in the southern part of 
Yucca Mountain, north of the Nye County Early Warning Detection Program (NC-EWDP) 
wells. Consequently, the extent to which the available data are representative for these areas is 
difficult to assess (Assumptions 1 and 2 in Table 4). 
The boreholes shown in Figure 2 and listed in Table 2 generally could be grouped by geographic 
area or by association with particular features, such as Fortymile Wash or the Gravity Fault, or by 
hydrochemical signature. Each group of boreholes is identified by a unique symbol and color, 
which are used in plots presented in later sections. The use of different symbols in the plots 
allows the differences (or similarities) in the concentrations of chemical and isotopic species to be 
more easily distinguished. The basis for grouping the boreholes in the manner shown in Figure 2 
is largely self-explanatory, but some further explanation for particular groups follows. 
Boreholes at Yucca Mountain were divided into (1) a northern group (YM-N), which includes 
boreholes along and north of Drillhole Wash, (2) an eastern group (YM-E) including borehole 
p#1, which extends to the carbonate aquifer, (3) a central group (YM-C), which includes 
boreholes located within the central block of Yucca Mountain, as defined by Day et al. (1998, 
p. 1, Map I-2601), and (4) a southern group (YM-S), which includes boreholes along and south of 
Dune Wash. 
Boreholes in the Crater Flat group (CF) include boreholes WT-10, WT-7, and H-6, which are 
located near Yucca Mountain but west of the Solitario Canyon Fault. Existing boreholes drilled 
as part of the NC-EWDP are generally located along the southern edge of Crater Flat, except for 
borehole NC-EWDP-5S, which is east of Fortymile Wash in southern Jackass Flats. The NCEWDP 
boreholes are grouped together with the CIND-R-LITE borehole into a single group (NCEWDP) 
despite the lack of association with a single geographic or hydrologic feature. 
Boreholes near Fortymile Wash were divided into a northern group (FMW-N), which includes 
the boreholes east and northeast of Yucca Mountain, and a southern group (FMW-S), which 
includes the boreholes between or along the main channels of Fortymile Wash in the Amargosa 
Desert, as shown in Claassen (1985, Fig. 3). Boreholes in the Amargosa Desert located to the 
east and west of the distributary channels of Fortymile Wash but not associated with other 
hydrologic or geographic features are included in the groups FMW-E and FMW-W, respectively. 
The Jackass Flats (JF) group consists of a single borehole (J-11), located in central Jackass Flats. 
The boreholes located near the community of Amargosa Valley are in the group LW. Boreholes 
near the Skeleton Hills and Specter Range Thrust Fault are grouped together (SH), as are 
boreholes located farther south near the Gravity Fault (GF). The Amargosa River group (AR) 
includes boreholes located near the southwest corner of the Site Model, the NEC Well west of 
Bare Mountain, and borehole 27N/4E-27bbb in California. Boreholes located near the

ANL-NBS-HS-000021, REV 00 58 of 131 August 2000 
confluence of the Amargosa River and Fortymile Wash drainages are grouped together 
(AR/FMW). This group does not include site 17S/49E-35ddd (Ash Tree Spring), which is 
included in the FMW-E group. 
6.5.1.1 Chloride 
The chloride (Cl) concentrations of groundwater samples in the Yucca Mountain vicinity are 
shown in Figure 5. The areal distribution clearly shows spatial zonations in Cl concentrations. 
Except for borehole p#1, where groundwater was sampled from the carbonate aquifer and from 
deep in the volcanic section where groundwater seems to be mixed with groundwater from the 
carbonate aquifer, the Cl concentrations of groundwater in the Yucca Mountain area generally 
are low (less than 9 mg L1) compared to areas to the west and east. Although few data are 
available, groundwater in eastern Crater Flat has low Cl concentrations compared to 
groundwater in western Crater Flat, a distinction that is preserved at the south end of Crater Flat 
at the NC-EWDP boreholes. Low Cl concentrations associated with the Fortymile Wash area 
east of Yucca Mountain extend southward into the Amargosa Desert, where the lowconcentration 
zone is bounded by areas having substantially higher Cl concentrations. 
Groundwater near the southwest corner of the Site-Model boundary has Cl concentrations in 
excess of 50 mg L1, as does the single sample from the NEC Well in the hydraulically 
upgradient area west of Bare Mountain. 
6.5.1.2 Sulfate 
The areal distribution of sulfate (SO4
2) (Figure 6) has patterns similar to those described for Cl 
(Figure 5). Except at borehole p#1 where the SO4
2 concentrations are much higher, 
groundwater at Yucca Mountain generally has SO4
2 concentrations less than 35 mg L1, whereas 
SO4
2 concentrations west and east of Yucca Mountain are moderately to substantially higher. 
Borehole J-11 in central Jackass Flat has a SO4
2 concentration of 449 mg L1. The 
compositional differences between groundwater in western and eastern Crater Flat are also 
evident in SO4
2 concentrations, with the difference that the SO4
2 concentration at Gexa Well 4 
in the northwest corner of the Site-Model Area more closely resembles groundwater in eastern 
(VH-1) rather than western (VH-2) Crater Flat. As is the case for Cl, the low SO4
2 
groundwater associated with Fortymile Wash east of Yucca Mountain also extends southward 
into the Amargosa Desert, where it is surrounded by groundwater having distinctly higher SO4
2 
concentrations. The groundwater with high Cl concentrations near the southwest corner of the 
Site-Model Area also has relatively high (100 to 200 mg L1) SO4
2 concentrations. 
Groundwater north and northwest of this area has similarly high SO4
2 concentrations. 
6.5.1.3 Bicarbonate 
The areal distribution of bicarbonate (HCO3
) is shown in Figure 7. The areal patterns for 
HCO3
 are similar to those described for SO4
2 and Cl with some differences. Groundwater 
with high (greater than 200 mg L1) HCO3
 concentrations is present in easternmost Crater Flat 
and western Yucca Mountain near Solitario Canyon. Elsewhere at Yucca Mountain, 
groundwater generally has HCO3
 concentrations less than 175 mg L1. Groundwater in central 
Jackass Flats at borehole J-11, where the high SO4
2 was noted previously, has one of the lowest 
HCO3
 concentrations (102 mg L1) in the map area. Groundwater near the Fortymile Wash 
drainage in the Amargosa Desert has much lower (less than 160 mg L1) HCO3
 concentrations 
than groundwater in the surrounding areas but has slightly higher HCO3
 concentrations than 
groundwater upgradient along Fortymile Wash.

ANL-NBS-HS-000021, REV 00 59 of 131 August 2000 
DTN: GS000700012847.001, GS930108315213.002, GS950808312322.001, MO0007MAJIONPH.002, MO0007MAJIONPH.003, 
MO0007MAJIONPH.005, MO0007MAJIONPH.006, MO0007MAJIONPH.007, MO0007MAJIONPH.008, MO0007MAJIONPH.009, 
MO0007MAJIONPH.010, MO0007MAJIONPH.011, MO0007MAJIONPH.012, MO0007MAJIONPH.013, MO0007MAJIONPH.014, 
MO0007MAJIONPH.015, MO0008MAJIONPH.017 
NOTE: This figure has color-coded data points and should not be read in a black and white version. 
Figure 5. Areal Distribution of Chloride in Groundwater 
525000.00 535000.00 545000.00 555000.00 565000.00 
4030000.00 
4040000.00 
4050000.00 
4060000.00 
4070000.00 
4080000.00 
4090000.00 
4100000.00 
5.00 to 6.00 
6.00 to 7.00 
7.00 to 8.00 
8.00 to 9.00 
9.00 to 10.00 
10.00 to 12.00 
12.00 to 14.00 
14.00 to 16.00 
16.00 to 18.00 
18.00 to 20.00 
20.00 to 30.00 
30.00 to 50.00 
50.00 to 75.00 
75.00 to 100.00 
Chloride (mg/L) 
Site-Model 
Boundary 
UTM-Y (meters) 
UTM-X (meters)

ANL-NBS-HS-000021, REV 00 60 of 131 August 2000 
DTN: GS000700012847.001, GS930108315213.002, GS950808312322.001, MO0007MAJIONPH.002, MO0007MAJIONPH.003, 
MO0007MAJIONPH.005, MO0007MAJIONPH.006, MO0007MAJIONPH.007, MO0007MAJIONPH.008, MO0007MAJIONPH.009, 
MO0007MAJIONPH.010, MO0007MAJIONPH.011, MO0007MAJIONPH.012, MO0007MAJIONPH.013, MO0007MAJIONPH.014, 
MO0007MAJIONPH.015, MO0008MAJIONPH.017 
NOTE: This figure has color-coded data points and should not be read in a black and white version. 
Figure 6. Areal Distribution of Sulfate in Groundwater 
525000.00 535000.00 545000.00 555000.00 565000.00 
4030000.00 
4040000.00 
4050000.00 
4060000.00 
4070000.00 
4080000.00 
4090000.00 
4100000.00 
5.00 to 10.00 
10.00 to 15.00 
15.00 to 20.00 
20.00 to 25.00 
25.00 to 30.00 
30.00 to 35.00 
35.00 to 40.00 
40.00 to 50.00 
50.00 to 100.00 
100.00 to 200.00 
200.00 to 400.00 
400.00 to 600.00 
Sulfate (mg/L) 
UTM-Y (meters) 
UTM-X (meters) 
Site-Model 
Boundary

ANL-NBS-HS-000021, REV 00 61 of 131 August 2000 
DTN: GS000700012847.001, GS930108315213.002, GS950808312322.001, MO0007MAJIONPH.002, MO0007MAJIONPH.003, 
MO0007MAJIONPH.005, MO0007MAJIONPH.006, MO0007MAJIONPH.007, MO0007MAJIONPH.008, MO0007MAJIONPH.009, 
MO0007MAJIONPH.010, MO0007MAJIONPH.011, MO0007MAJIONPH.012, MO0007MAJIONPH.013, MO0007MAJIONPH.014, 
MO0007MAJIONPH.015, MO0008MAJIONPH.017 
NOTE: This figure has color-coded data points and should not be read in a black and white version. 
Figure 7. Areal Distribution of Bicarbonate in Groundwater 
525000.00 535000.00 545000.00 555000.00 565000.00 
4030000.00 
4040000.00 
4050000.00 
4060000.00 
4070000.00 
4080000.00 
4090000.00 
4100000.00 
100.00 to 110.00 
110.00 to 120.00 
120.00 to 130.00 
130.00 to 140.00 
140.00 to 150.00 
150.00 to 160.00 
160.00 to 170.00 
170.00 to 180.00 
180.00 to 190.00 
190.00 to 200.00 
200.00 to 300.00 
300.00 to 400.00 
400.00 to 600.00 
Bicarbonate (mg/L) 
UTM-Y (meters) 
UTM-X (meters) 
Site-Model 
Boundary

ANL-NBS-HS-000021, REV 00 62 of 131 August 2000 
6.5.1.4 Calcium 
The calcium (Ca2+) concentrations of groundwater at Yucca Mountain are generally less than 20 
mg L1 (Figure 8), except at borehole p#1 where groundwater from the carbonate aquifer has a 
concentration of 100 mg L1. Along the eastern edge of Crater Flat and in western Yucca 
Mountain, Ca2+ concentrations are less than 5 mg L1. The Ca2+ concentration is higher in 
western Crater Flat at borehole VH-2 than in eastern Crater Flat at borehole VH-1. The Ca2+ 
concentration at Gexa Well 4 in the northwest corner of the Site-Model Area is similar to the 
value at VH-1 and at NC-EWDP wells southeast of Crater Flat. The Ca2+ concentration is 
relatively high (82 mg L1) at borehole J-11 in central Jackass Flats, where SO4
2 is also 
relatively high (Figure 6). The Ca2+ concentration along Fortymile Wash is between 10 to 20 
mg L1 east and northeast of Yucca Mountain and increases to values generally between 20 to 30 
mg L1 in the Amargosa Desert. The Ca2+ concentration increases to either side of Fortymile 
Wash in the Amargosa Desert. Groundwater Ca2+ concentrations in the southwest corner of the 
Site-Model Area are similar to the Ca2+ concentrations in upgradient areas in western Crater Flat 
and west of Bare Mountain. 
6.5.1.5 Magnesium 
The areal distribution of magnesium (Mg2+) (Figure 9) shows that Mg2+ concentrations in 
groundwater at Yucca Mountain range from 0.1 to 1.6 mg L1, except at borehole p#1 where the 
Mg2+ concentration is 10 mg L1 in the volcanic aquifer and 39 mg L1 in the carbonate aquifer. 
The Mg2+ concentration in groundwater in western Crater Flat at borehole VH-2 is high (30 mg 
L1) compared to groundwater at borehole VH-1 (1.5 mg L1). In NC-EWDP wells south of 
Crater Flat, Mg2+ concentrations range from less than 1 to 31 mg L1, with concentrations 
generally increasing to the west. Concentrations of Mg2+ are low (0.2 mg L1) at the 
northernmost borehole along Fortymile Wash (a#2) but are generally between 2 and 3 mg L1 
along the length of Fortymile Wash east of Yucca Mountain and in the Amargosa Desert. In the 
eastern part of the Amargosa Desert near Amargosa Valley, Mg2+ concentrations can be both 
higher and lower than in groundwater near the adjacent reach of Fortymile Wash. South of the 
southern boundary of the Site Model near the Gravity Fault, Mg2+ concentrations are generally 
between 5 and 20 mg L1. In the southwest corner of the model area, Mg2+ concentrations 
generally are between 5 to 10 mg L1, but a few samples have concentrations between 10 and 20 
mg L1, similar to the concentration of groundwater at the NEC Well west of Bare Mountain (14 
mg L1). The concentration of Mg2+ is 13 mg L1 at borehole J-11 in central Jackass Flats. 
6.5.1.6 Sodium 
The areal distribution of sodium (Na+) is shown in Figure 10. Excluding data from the carbonate 
aquifer (borehole p#1), the Na+ concentrations of groundwater at Yucca Mountain range between 
46 and 120 mg L1. The values toward the high end of this range are generally in the western 
part of Yucca Mountain and are similar to values along the eastern edge of Crater Flat. The Na+ 
concentrations of groundwater in the NC-EWDP boreholes west of Fortymile Wash are generally 
between 40 and 80 mg L1, except at borehole NC-EWDP-3D where the Na+ concentration was 
anomalously high (113 mg L1). The Na+ concentrations of groundwater at borehole NCEWDP-
55 west of the Striped Hills and at J-11 in central Jackass Flats are also high (149 and 
143 mg L1, respectively).

ANL-NBS-HS-000021, REV 00 63 of 131 August 2000 
DTN: GS000700012847.001, GS930108315213.002, GS950808312322.001, MO0007MAJIONPH.002, MO0007MAJIONPH.003, 
MO0007MAJIONPH.005, MO0007MAJIONPH.006, MO0007MAJIONPH.007, MO0007MAJIONPH.008, MO0007MAJIONPH.009, 
MO0007MAJIONPH.010, MO0007MAJIONPH.011, MO0007MAJIONPH.012, MO0007MAJIONPH.013, MO0007MAJIONPH.014, 
MO0007MAJIONPH.015, MO0008MAJIONPH.017 
NOTE: This figure has color-coded data points and should not be read in a black and white version. 
Figure 8. Areal Distribution of Calcium in Groundwater 
525000.00 535000.00 545000.00 555000.00 565000.00 
4030000.00 
4040000.00 
4050000.00 
4060000.00 
4070000.00 
4080000.00 
4090000.00 
4100000.00 
0.00 to 5.00 
5.00 to 10.00 
10.00 to 15.00 
15.00 to 20.00 
20.00 to 25.00 
25.00 to 30.00 
35.00 to 40.00 
45.00 to 50.00 
50.00 to 60.00 
60.00 to 75.00 
75.00 to 100.00 
100.00 to 125.00 
Calcium (mg/L) 
UTM-X (meters) 
UTM-Y (meters) 
Site-Model 
Boundary

ANL-NBS-HS-000021, REV 00 64 of 131 August 2000 
DTN: GS000700012847.001, GS930108315213.002, GS950808312322.001, MO0007MAJIONPH.002, MO0007MAJIONPH.003, 
MO0007MAJIONPH.005, MO0007MAJIONPH.006, MO0007MAJIONPH.007, MO0007MAJIONPH.008, MO0007MAJIONPH.009, 
MO0007MAJIONPH.010, MO0007MAJIONPH.011, MO0007MAJIONPH.012, MO0007MAJIONPH.013, MO0007MAJIONPH.014, 
MO0007MAJIONPH.015, MO0008MAJIONPH.017 
NOTE: This figure has color-coded data points and should not be read in a black and white version. 
Figure 9. Areal Distribution of Magnesium in Groundwater 
525000.00 535000.00 545000.00 555000.00 565000.00 
4030000.00 
4040000.00 
4050000.00 
4060000.00 
4070000.00 
4080000.00 
4090000.00 
4100000.00 
0.00 to 0.25 
0.25 to 0.50 
0.50 to 1.00 
1.00 to 1.50 
1.50 to 2.00 
2.00 to 2.50 
2.50 to 3.00 
3.00 to 4.00 
4.00 to 5.00 
5.00 to 10.00 
10.00 to 20.00 
20.00 to 40.00 
Magnesium (mg/L) 
UTM-Y (meters) 
UTM-X (meters) 
Site-Model 
Boundary

ANL-NBS-HS-000021, REV 00 65 of 131 August 2000 
DTN: GS000700012847.001, GS930108315213.002, GS950808312322.001, MO0007MAJIONPH.002, MO0007MAJIONPH.003, 
MO0007MAJIONPH.005, MO0007MAJIONPH.006, MO0007MAJIONPH.007, MO0007MAJIONPH.008, MO0007MAJIONPH.009, 
MO0007MAJIONPH.010, MO0007MAJIONPH.011, MO0007MAJIONPH.012, MO0007MAJIONPH.013, MO0007MAJIONPH.014, 
MO0007MAJIONPH.015, MO0008MAJIONPH.017 
NOTE: This figure has color-coded data points and should not be read in a black and white version. 
Figure 10. Areal Distribution of Sodium in Groundwater 
525000.00 535000.00 545000.00 555000.00 565000.00 
4030000.00 
4040000.00 
4050000.00 
4060000.00 
4070000.00 
4080000.00 
4090000.00 
4100000.00 
30.00 to 40.00 
40.00 to 50.00 
50.00 to 60.00 
60.00 to 70.00 
70.00 to 80.00 
80.00 to 90.00 
90.00 to 100.00 
100.00 to 110.00 
110.00 to 120.00 
120.00 to 130.00 
130.00 to 140.00 
140.00 to 150.00 
150.00 to 175.00 
Sodium (mg/L) 
UTM-X (meters) 
UTM-Y (meters) 
Site-Model 
Boundary

ANL-NBS-HS-000021, REV 00 66 of 131 August 2000 
Most of the groundwater samples along Fortymile Wash have Na+ concentrations between 35 
and 50 mg L1; there are not any obvious trends in the Na+ concentrations of groundwater 
beneath Fortymile Wash east of Yucca Mountain and beneath the wash in the Amargosa Desert. 
In the Amargosa Desert, Na+ concentrations in groundwater increase away from Fortymile Wash 
in both eastward and westward directions. Groundwater in the southwest corner of the Site- 
Model Area has high Na+ concentrations (130 to 180 mg L1) similar to that of the NEC Well 
(170 mg L1) west of Bare Mountain, whereas groundwater slightly further east along the 
southern boundary of the Site-Model Area has lower Na+ concentrations similar to groundwater 
in Crater Flat. 
6.5.1.7 Potassium 
The areal distribution of potassium (K+) (Figure 11) shows that K+ concentrations in 
groundwater at Yucca Mountain range between 1 and 6 mg L1, except in the carbonate aquifer 
at borehole p#1 where the K+ concentration is 12 mg L1. The highest K+ concentration in 
groundwater within the map area is at borehole J-11 in central Jackass Flats (15 mg L1). The K+ 
concentrations in groundwater in western Crater Flat at borehole VH-2 is high (8 mg L1) 
compared to groundwater at borehole VH-1 (1.9 mg L1). In the NC-EWDP wells south of 
Crater Flat, K+ concentrations range from 3.0 to 10 mg L1, with concentrations generally 
increasing to the west. Concentrations of K+ are low (between 1.0 and 1.5 mg L1) at the 
northernmost borehole along Fortymile Wash (a#2) but are generally between 5 and 8 mg L1 
along the length of Fortymile Wash east of Yucca Mountain and in the Amargosa Desert. In the 
eastern part of the Amargosa Desert, K+ concentrations can be both higher and lower than in 
groundwater near the adjacent reach of Fortymile Wash. In the southwest corner of the model 
area, K+ concentrations generally are between 10 to 12 mg L1, concentrations that are similar to 
those of groundwater at the NEC Well west of Bare Mountain (10 mg L1). 
6.5.1.8 Delta Deuterium 
The areal distribution of delta deuterium (dD) values is shown in Figure 12 (this isotopic 
parameter is defined and discussed in Section 6.5.4.1). The dD values in groundwaters from the 
Yucca Mountain area range from about 104 per mil at borehole H-4 to about 99 per mil at 
borehole G-2. In Crater Flat, the dD values measured in water from borehole VH-1 (108 per 
mil) and from Gexa Well 4 (106 per mil) are substantially more depleted (i.e., more negative) 
than that for water from borehole VH-2 (99 per mil). The dD values at borehole NC-EWDP- 
1D (101.3 per mil) and at borehole NC-EWDP-3D (105.6 per mil) are similar to the values at 
upgradient boreholes VH-2 and VH-1, respectively. 
The dD values of groundwater near Fortymile Wash show a general trend toward more depleted 
values from north to south, ranging from about 93 per mil at borehole a#2 near the northern 
boundary of the Site-Model Area to values that are generally 100 per mil or less near the 
southern boundary of the model area. East of Yucca Mountain, groundwater beneath Fortymile 
Wash has dD values of about 97 per mil. The dD value of groundwater at borehole NC-EWDP- 
2D (104 per mil) is substantially lighter than that for groundwater associated with Fortymile 
Wash.

ANL-NBS-HS-000021, REV 00 67 of 131 August 2000 
DTN: GS000700012847.001, GS930108315213.002, GS950808312322.001, MO0007MAJIONPH.002, MO0007MAJIONPH.003, 
MO0007MAJIONPH.005, MO0007MAJIONPH.006, MO0007MAJIONPH.008, MO0007MAJIONPH.009, MO0007MAJIONPH.010, 
MO0007MAJIONPH.011, MO0007MAJIONPH.012, MO0007MAJIONPH.013, MO0007MAJIONPH.014, MO0007MAJIONPH.015, 
MO0008MAJIONPH.017 
NOTE: This figure has color-coded data points and should not be read in a black and white version. 
Figure 11. Areal Distribution of Potassium in Groundwater 
525000.00 535000.00 545000.00 555000.00 565000.00 
4030000.00 
4040000.00 
4050000.00 
4060000.00 
4070000.00 
4080000.00 
4090000.00 
4100000.00 
1.00 to 1.50 
1.50 to 2.00 
2.00 to 2.50 
2.50 to 3.00 
3.00 to 4.00 
4.00 to 5.00 
5.00 to 6.00 
6.00 to 8.00 
8.00 to 10.00 
10.00 to 12.00 
12.00 to 14.00 
14.00 to 16.00 
Potassium (mg/L) UTM-X (meters) 
UTM-Y (meters) 
Site-Model 
Boundary

ANL-NBS-HS-000021, REV 00 68 of 131 August 2000 
DTN: GS000700012847.001, GS950808312322.001,GS970708312323.001, MO0007GNDWTRIS.002, MO0007GNDWTRIS.003, 
MO0007GNDWTRIS.004, MO0007GNDWTRIS.005, MO0007GNDWTRIS.006, MO0007GNDWTRIS.007, 
MO0007GNDWTRIS.008, MO0007GNDWTRIS.009, MO0007GNDWTRIS.010, MO0007GNDWTRIS.011, 
MO0007GNDWTRIS.012, USGS (n.d.) (see Assumption 23 in Table 4) 
NOTE: This figure has color-coded data points and should not be read in a black and white version. 
Figure 12. Areal Distribution of Delta Deuterium in Groundwater 
525000.00 535000.00 545000.00 555000.00 565000.00 
4030000.00 
4040000.00 
4050000.00 
4060000.00 
4070000.00 
4080000.00 
4090000.00 
4100000.00 
-115.00 to -108.00 
-108.00 to -107.00 
-107.00 to -106.00 
-106.00 to -105.00 
-105.00 to -104.00 
-104.00 to -103.00 
-103.00 to -102.00 
-102.00 to -101.00 
-101.00 to -100.00 
-100.00 to -99.00 
-99.00 to -98.00 
-98.00 to -97.00 
-97.00 to -95.00 
-95.00 to -92.00 
delta deuterium 
UTM-Y (meters) 
UTM-X (meters) 
Site-Model 
Boundary

ANL-NBS-HS-000021, REV 00 69 of 131 August 2000 
Groundwater in the Amargosa Desert has variable dD values, and spatial patterns are not as 
regular as for other chemical species. Groundwater in the eastern part of the Amargosa Desert is 
generally more depleted in dD than groundwater farther to the west near Fortymile Wash. The 
dD values for groundwater in the southwest corner of the Site-Model Area vary between 104 
and 102 per mil. 
6.5.1.9 Delta Oxygen-18 
Figure 13 shows the areal distribution of delta oxygen-18 (d18O) values for the Yucca Mountain 
area (this isotopic parameter is defined and discussed in Section 6.5.4.1). Groundwater at Yucca 
Mountain has d18O values between 13.3 and 14 per mil, with groundwater in western Yucca 
Mountain near Solitario Canyon having values that fall toward the more depleted end of this 
range. Groundwater at borehole VH-1 in Crater Flat has a d18O value of 14.2 per mil, similar to 
the d18O value for groundwater at Gexa Well 4 (14.1 per mil), whereas groundwater at VH-2 
has a d18O value of 13.4 per mil. Groundwaters sampled from the NC-EWDP wells along the 
southern edge of Crater Flat generally have d18O values that are similar to those in wells directly 
to the north at boreholes VH-1 AND VH-2. 
The d18O values of groundwater near Fortymile Wash fall within a relatively narrow range 
(13.2 to 12.8 per mil) north of the Amargosa Desert. The d18O values of groundwater near 
Fortymile Wash generally are distinct from those of groundwater farther east or west from the 
Wash, although near the southern boundary of the Site-Model Area, this distinction becomes less 
well defined. 
6.5.1.10 Delta Carbon-13 
The areal distribution of delta carbon-13 (d13C) values is shown in Figure 14 (this isotopic 
parameter is defined and discussed in Section 6.5.4.1). Excluding the data from borehole p#1, 
where groundwater has d13C values of 2.3 per mil in the carbonate aquifer and 4.2 per mil in 
the volcanic aquifer, the d13C values of groundwater at Yucca Mountain vary between 14.4 per 
mil at borehole UZ-14 to 4.9 per mil at borehole H-3. Although patterns are complex on a 
borehole-by-borehole basis, groundwater in the northern part of Yucca Mountain is generally 
more depleted in 13C than groundwater in the southern part of Yucca Mountain, which has d13C 
values similar to that of groundwater in Crater Flat at borehole VH-1 (8.5 per mil). The d13C 
values of groundwater in the NC-EWDP boreholes at the southern edge of Crater Flat increase 
toward the west. 
The d13C values of groundwater near Fortymile Wash generally increase between the north and 
south boundaries of the Site-Model Area, although local reversals in this trend are evident. The 
groundwater d13C values near Fortymile Wash are generally more depleted than the d13C values 
toward the western and eastern parts of the Amargosa Desert. The d13C values of groundwater 
near the southwest corner of the Site-Model Area (5.7 and 6.2 per mil) are similar to the value 
at the NEC Well (5.9 per mil) west of Bare Mountain.

ANL-NBS-HS-000021, REV 00 70 of 131 August 2000 
DTN: GS000700012847.001, GS950808312322.001,GS970708312323.001, MO0007GNDWTRIS.002, MO0007GNDWTRIS.003, 
MO0007GNDWTRIS.004, MO0007GNDWTRIS.005, MO0007GNDWTRIS.006, MO0007GNDWTRIS.007, 
MO0007GNDWTRIS.008, MO0007GNDWTRIS.009, MO0007GNDWTRIS.010, MO0007GNDWTRIS.011, 
MO0007GNDWTRIS.012, USGS (n.d.) (see Assumption 23 in Table 4) 
NOTE: This figure has color-coded data points and should not be read in a black and white version. 
Figure 13. Areal Distribution of Delta Oxygen-18 in Groundwater 
525000.00 535000.00 545000.00 555000.00 565000.00 
4030000.00 
4040000.00 
4050000.00 
4060000.00 
4070000.00 
4080000.00 
4090000.00 
4100000.00 
-16.00 to -15.00 
-15.00 to -14.00 
-14.00 to -13.80 
-13.80 to -13.60 
-13.60 to -13.40 
-13.40 to -13.20 
-13.20 to -13.00 
-13.00 to -12.80 
-12.80 to -12.60 
-12.60 to -12.40 
-12.40 to -12.20 
-12.20 to -12.00 
delta oxygen-18 
UTM-X (meters) 
UTM-Y (meters) 
Site-Model 
Boundary

ANL-NBS-HS-000021, REV 00 71 of 131 August 2000 
DTN: GS930908312323.003, GS950808312322.001, MO0007GNDWTRIS.002, MO0007GNDWTRIS.003, 
MO0007GNDWTRIS.005, MO0007GNDWTRIS.006, MO0007GNDWTRIS.007, MO0007GNDWTRIS.008, 
MO0007GNDWTRIS.009, MO0007GNDWTRIS.010, MO0007GNDWTRIS.011, MO0007GNDWTRIS.012, USGS (n.d.) (see 
Assumption 23 in Table 4) 
NOTE: This figure has color-coded data points and should not be read in a black and white version. 
Figure 14. Areal Distribution of Delta Carbon-13 in Groundwater 
525000.00 535000.00 545000.00 555000.00 565000.00 
4030000.00 
4040000.00 
4050000.00 
4060000.00 
4070000.00 
4080000.00 
4090000.00 
4100000.00 
-18.00 to -16.00 
-16.00 to -14.00 
-14.00 to -12.00 
-12.00 to -11.00 
-11.00 to -10.00 
-10.00 to -9.00 
-9.00 to -8.00 
-8.00 to -7.00 
-7.00 to -6.00 
-6.00 to -5.00 
-5.00 to -4.00 
-4.00 to -2.00 
Delta Carbon-13 
UTM-X (meters) 
UTM-Y (meters) 
Site-Model 
Boundary

ANL-NBS-HS-000021, REV 00 72 of 131 August 2000 
6.5.1.11 Carbon-14 Activity 
The areal distribution of 14C activity in pmc is shown in Figure 15. Excluding groundwater from 
borehole p#1, which has a 14C activity of 2.3 pmc in the carbonate aquifer and 3.5 pmc in the 
volcanic aquifer, the 14C activity of groundwater at Yucca Mountain ranges from 10.5 pmc at 
borehole H-3 to 25 pmc at borehole UZ-14. Groundwater at the eastern edge of Crater Flat near 
Solitario Canyon has some of the lowest 14C activities of groundwater in the map area, with 
values as low as 7.3 pmc at borehole WT-10 and 10 pmc in a sample from borehole H-6. 
Groundwater 14C activities are slightly higher farther to the west in Crater Flat at borehole VH-1 
(12 pmc). The existing data indicate that groundwater at borehole NC-EWDP-3D (10 pmc) is 
similar to the 14C activity of groundwater at borehole VH-1. The groundwater at borehole NCEWDP-
2D has a 14C activity of 23.5 pmc, similar to groundwater in Dune and Fortymile Washes. 
Groundwater near Fortymile Wash has 14C activities that range from over 60 pmc at borehole 
a#2 near the northern boundary of the model area to values under 20 pmc near the southern 
boundary of the model area. South of the southern boundary of the Site-Model Area, 14C 
activities range from 10 to 40 pmc. The single groundwater 14C activity measured in the 
southwest corner of the Site-Model Area is 31 pmc, which is considerably larger than the value 
of 12 pmc measured in Crater Flat and similar to the value of 29 pmc measured in groundwater 
at the NEC Well west of Bare Mountain. 
6.5.1.12 234U/238U Activity Ratios 
Figure 16 shows the areal distribution of uranium concentrations and 234U/238U activity ratios. 
The highest activity ratios in the region are found at Yucca Mountain and are localized in an area 
between the Yucca Mountain crest and the eastern edge of Busted Butte and between the 
northern extent of Yucca Mountain and just south of Busted Butte. The activity ratios decrease 
in all directions from this central area. Moving southward along the Fortymile Wash drainage, 
the ratios first increase to values from 4.5 to 6.0 at wells J-13 and J-12 then decrease to values 
below 3.0 in the northern Amargosa Desert. In Crater Flat, the ratios decrease from east to west. 
6.5.2 Regional Flow Paths Inferred from Hydrochemical Data 
Groundwater flow paths were estimated from areal plots of dissolved ions and isotopes based on 
compositional differences and similarities between areas. The potentiometric surface map 
(Figure 4) was used to determine which areas of similar chemical and isotopic composition could 
potentially be located along the same flow path with allowances made for the possibility that 
flow paths could be somewhat oblique to the potentiometric gradient because of possible 
anisotropy in permeability. 
Groundwater chemistry can vary for a number of reasons, including changes in the composition 
of recharge waters over time, variable soil/rock/water/gas interactions, and mixing between 
waters of different compositions. This preliminary analysis assumes that the groundwater 
chemistry data obtained on a water sample from a given well is representative of the 
groundwater at that location (Assumption 2 in Table 4). That is, it is assumed vertical variations 
in groundwater chemistry in the volcanic aquifer at a given location are insignificant 
(Assumption 4). Given this assumption, the available water chemistry data can be used to define 
flow paths in two dimensions and to interpret relations between groundwaters from different 
regions (Assumption 4).

ANL-NBS-HS-000021, REV 00 73 of 131 August 2000 
DTN: GS930908312323.003, GS950808312322.001, MO0007GNDWTRIS.002, MO0007GNDWTRIS.003, 
MO0007GNDWTRIS.005, MO0007GNDWTRIS.006, MO0007GNDWTRIS.007, MO0007GNDWTRIS.008, 
MO0007GNDWTRIS.009, MO0007GNDWTRIS.010, MO0007GNDWTRIS.011, MO0007GNDWTRIS.012, USGS (n.d.) (see 
assumption 23 in Table 4) 
NOTE: This figure has color-coded data points and should not be read in a black and white version. 
Figure 15. Areal Distribution of Carbon-14 in Groundwater 
525000.00 535000.00 545000.00 555000.00 565000.00 
4030000.00 
4040000.00 
4050000.00 
4060000.00 
4070000.00 
4080000.00 
4090000.00 
4100000.00 
0.00 to 5.00 
5.00 to 10.00 
10.00 to 15.00 
15.00 to 20.00 
20.00 to 25.00 
25.00 to 30.00 
30.00 to 35.00 
35.00 to 40.00 
40.00 to 45.00 
45.00 to 50.00 
50.00 to 55.00 
55.00 to 60.00 
60.00 to 65.00 
Carbon-14 (pmc) 
UTM-Y (meters) 
UTM-X (meters) 
Site-Model 
Boundary

ANL-NBS-HS-000021, REV 00 74 of 131 August 2000 
DTN: GS930108315213.004; GS960908315215.013; GS980108312322.003; GS980208312322.006; GS980908312322.009 
NOTE: This figure has color-coded data points and should not be read in a black and white version. 
Figure 16. Areal Distributions of Uranium Concentration and 234U/238U Activity Ratio in Groundwater 
In general, the various chemical constituents in groundwater are affected to widely varying 
extents by soil/rock/water/gas interactions. Some readily measured constituents such as chloride, 
bromide, and the isotopes of hydrogen and oxygen show minimal effects from 
soil/rock/water/gas interactions at ambient aquifer temperatures. The concentrations of these 
constituents are controlled primarily by the composition of recharge waters and by mixing of 
waters of different compositions. That is, these constituents show conservative behavior 
(Langmuir 1997, p. 292). Because the isotopic compositions of hydrogen and oxygen in 
recharge waters have almost certainly changed over time, it is to be expected that isotopic 
variability would be evident in groundwaters of different ages (Benson and Klieforth 1989, 
Fig. 11; Winograd et al. 1992, Fig. 2).

ANL-NBS-HS-000021, REV 00 75 of 131 August 2000 
Flow paths can be traced using conservative constitutents only where compositional differences 
exist that allow some directions to be eliminated as possible flow directions. Some chemical and 
isotopic species in some areas have relatively uniform compositions and, thus, provide no 
information about flow paths. In other areas, they show more distinct compositional differences 
and, thus, can be used to infer flow directions. Because no single chemical or isotopic species 
varies sufficiently to determine flow paths everywhere in the study area, multiple chemical and 
isotopic species are used to construct the flow paths inferred in this section. 
The analysis of flow paths that follows assumes that Cl and SO4
2 values are conservative in 
addition to certain chemical species, such as dD, d18O, Na+, and Ca2+ (Assumption 5 in Table 4). 
None of these species is truly conservative. For example, there are potential mineral sources of 
SO4
2 in the map area. Additionally, groundwater in the carbonate aquifer is high in both Cl and 
SO4
2 compared to groundwater in the volcanic aquifer (Figures 5 and 6), so upwelling from the 
carbonate aquifer could potentially modify the concentrations of Cl and SO4
2 in the volcanic 
aquifer. In spite of the potential nonconservatism of Na+ and Ca2+, the contrast in 
concentrations between some areas is great enough that meaningful inferences about flow 
directions can be made. 
6.5.2.1 Regional Flow Paths 
The flow paths determined from the areal distribution maps described in Section 6.5.1 are 
superimposed on a map showing the areal distribution of chloride (Figure 17). These paths were 
developed, in part, based on the maps of other chemical and isotopic data. The reasoning by 
which each of the flow paths were developed follows. 
Flow Path 1 connects the area in the vicinity of the NEC Well west of Bare Mountain with the 
area in the southwest corner of the model area. A more north-south flow path from Crater Flat to 
the southwest corner of the map area was ruled highly improbable based on the dissimilarities in 
Cl and Na+ values in these two areas (Figures 5 and 10). 
Flow Path 2 connects areas near Fortymile Canyon and Fortymile Wash northeast and east of 
Yucca Mountain with the Fortymile Wash area in the Amargosa Desert. This flow line is 
constrained on the east by the much higher Cl, SO4
2, and Na+ concentrations in groundwater in 
Jackass Flats and the southeast corner of the model area (Figures 5, 6, and 10). Near Yucca 
Mountain, the position of this flow line is constrained on the west by the distinct dD and d18O 
composition of groundwater at Yucca Mountain (Figures 12 and 13), including groundwater at 
the CIND-R-LITE and NC-EWDP-2D wells south of Yucca Mountain. Near the southern 
boundary of the Site Model, Flow Path 2 is constrained by the higher Cl, SO4
2, and Na+ 
concentrations of groundwater west of the Wash (Figures 5, 6, and 10). 
Flow Path 3 connects areas in the northwest corner of the Site-Model Area, central Crater Flat, 
the NC-EWDP wells, and wells along the southern boundary of the Site Model. The flow path is 
constrained on the west by the higher Cl, SO4
2, and Ca2+ concentrations in western Crater Flat 
at borehole VH-2, the western NC-EWDP wells at the southern edge of Crater Flat, and the 
southwestern corner of the Site-Model boundary (Figures 5, 6, and 8). Additional constraints are

ANL-NBS-HS-000021, REV 00 76 of 131 August 2000 
DTN: GS000700012847.001, GS930108315213.002, GS950808312322.001, MO0007MAJIONPH.002, MO0007MAJIONPH.003, 
MO0007MAJIONPH.005, MO0007MAJIONPH.006, MO0007MAJIONPH.007, MO0007MAJIONPH.008, MO0007MAJIONPH.009, 
MO0007MAJIONPH.010, MO0007MAJIONPH.011, MO0007MAJIONPH.012, MO0007MAJIONPH.013, MO0007MAJIONPH.014, 
MO0007MAJIONPH.015, MO0008MAJIONPH.017 
NOTE: This figure has color-coded data points and should not be read in a black and white version. Flow paths are 
drawn based on Assumptions 4 and 5 in Table 4. 
Figure 17. Regional Flow Paths Inferred from Hydrochemical and Isotopic Data 
525000 535000 545000 555000 565000 
4030000 
4040000 
4050000 
4060000 
4070000 
4080000 
4090000 
4100000 
5.00 to 6.00 
6.00 to 7.00 
7.00 to 8.00 
8.00 to 9.00 
9.00 to 10.00 
10.00 to 12.00 
12.00 to 14.00 
14.00 to 16.00 
16.00 to 18.00 
18.00 to 20.00 
20.00 to 30.00 
30.00 to 50.00 
50.00 to 75.00 
75.00 to 100.00 
Chloride (mg/L) 
Site-Model 
Boundary 
UTM-Y (meters) 
UTM-X (meters) 
? 
? 
Path #1 
Path #2 
Path #4 
Path #3 
Path #5
Path #6

ANL-NBS-HS-000021, REV 00 77 of 131 August 2000 
imposed by the distinct dD and d18O composition of groundwater at boreholes VH-1 and VH-2 
in central Crater Flat (Figures 12 and 13) and by the distinctly higher Na+ concentration of 
groundwater in the southwest corner of the model area (Figure 10). The starting location for this 
flow path was determined based on the similarity of the SO4
2 and Ca2+ concentrations and dD 
and d18O values of groundwater at Gexa Well 4 in the northwest corner of the model area to 
groundwater at VH-1 in central Crater Flat (Figures 6, 8, 12, and 13). The Cl and Na+ 
concentrations of groundwater at Gexa Well 4 were not clearly associated with groundwater in 
either western or eastern Crater Flat (Figures 5 and 10). 
Flow Path 4 connects areas in central Jackass Flats and Amargosa Valley to wells located south 
of the model boundary near the Gravity Fault. This flow path was defined by the western extent 
of groundwater with high Cl, SO4
2, and Na+ concentrations east of Fortymile Wash (Figures 5, 
6, and 10). The position of this flow path is poorly constrained by data in central Jackass Flats 
and may be further to the west than is shown, as also indicated by the fact that the high Ca2+ and 
SO4
2 concentrations at borehole J-11 have no downgradient counterparts. Near the southeast 
corner of the Site-Model Area, groundwaters east of the flow path are isotopically lighter than 
groundwaters west of the flow path, supporting the contention that groundwaters east and west of 
this flow path have different origins (Figures 12 and 13). No isotopic data are available from 
borehole J-11 to provide possible links between groundwaters in central Jackass Flats and 
downgradient groundwaters. The bicarbonate concentrations in the southeast corner of the 
model are also much higher than that for groundwater from borehole J-11 (Figure 7), indicating 
possible interaction of groundwater from Jackass Flats with carbonate rocks that crop out in the 
area or another source of water altogether contributing to the southeast corner of the model area. 
The location of Flow Path 5 was based primarily on contrasts between the relatively high Cl and 
SO4
2 concentrations of groundwater in Crater Flat and the much lower Cl and SO4
2 
concentrations of groundwater under Yucca Mountain and Fortymile Wash (Figures 5 and 6). 
The distal end of the flow line was a point near the southern boundary of the flow model that had 
Cl and SO4
2 concentrations intermediate between the groundwater typical of Yucca Mountain 
and Crater Flat. This line was then extended upgradient through southern Yucca Mountain and 
Crater Flat. Because of the lack of data toward the upper part of the flow-model area, the flow 
path in this area is queried. 
The regional flow paths constructed on the basis of the hydrochemical and isotopic data 
(Figure 17) are generally consistent with flow paths that could be inferred from the 
potentiometric surface (Figure 4), but they have a stronger north-south component. This stronger 
north-south component could be reflecting the general north-south structural fabric of the rock, 
the inability of the method to account for vertical heterogeneities in groundwater chemistry 
within a borehole, or simply the sparseness of data in certain regions of the model area. It is 
interesting that regional flow lines appear to be traceable from hydrochemical and isotopic data 
even where flow lines converge to the discharge areas south of the model boundary, suggesting 
long-term stability of the hypothesized flow paths over thousands to tens of thousands of years.

ANL-NBS-HS-000021, REV 00 78 of 131 August 2000 
6.5.2.2 Likely Flow Paths from the Potential Repository Area 
General flow paths in the Yucca Mountain area were constructed by identifying areas that had 
similar concentrations of conservative chemical species, such as chloride or sulfate, and tracing a 
path through these chemically similar areas in a downgradient direction. Of particular interest 
for this report are the paths leading from the potential repository area, such as the one 
constructed primarily on the basis of groundwater chloride concentrations (Figure 17). This 
pathway (Flow Path 6) starts with groundwater from the repository area just east of Yucca 
Mountain Crest that has chloride concentrations of about 6 mg L1. The pathway follows wells 
along Dune Wash with similarly low chloride concentrations before turning south-southwest 
near Fortymile Wash. Well WT#12, located immediately south of Dune Wash, has a chloride 
concentration of 7.8 mg L1, indicating that the dilute water beneath Dune Wash probably flows 
southeast along the Dune Wash Fault towards Fortymile Wash before turning south-southwest, 
rather than flowing directly south under Dune Wash. From the intersection of Dune Wash and 
Fortymile Wash, the only downgradient borehole with a chloride concentration of approximately 
6 mg L1 is borehole NC-EWDP-2D. Groundwater at this borehole has a d18O value of 14.1 per 
mil, a value that indicates this water was probably not derived from the Fortymile Wash where 
d18O values are generally 13.2 to 12.8 per mil (Figure 13). Borehole NC-EWDP-2D provides 
the basis for extending Flow Path 6 south-southwest from the Dune Wash/Fortymile Wash area 
along the western margin of Fortymile Wash. South of borehole NC-EWDP-2D, the pathway is 
constrained by the presence of two areas of groundwater with much higher chloride 
concentrations: (1) a western zone, composed of groundwater flowing south from Crater Flat 
and, possibly, southeast from Oasis Valley; and (2) an eastern zone, composed of groundwater 
flowing southwest from Jackass Flats and from leakage upward from the carbonate aquifer near 
the Gravity Fault (Winograd and Thordarson 1975, pp. C84C85, C112). Groundwater in wells 
south of NC-EWDP-2D with chloride concentrations of approximately 6 mg L1 have isotopic 
(dD and d18O) characteristics that indicate the water may have been recharged by overland flow 
during the late Pleistocene (Section 6.5.7.2.1). The hypothesized flow path was extended south 
from NC-EWDP-2D by keeping the path to the west of the axis of Fortymile Wash and east of 
the more highly concentrated water from Crater Flat and Oasis Valley. 
Importantly, the chloride data shown in Figure 17, as well as other chemical and isotopic data, 
suggest that groundwater from beneath the potential repository area does not flow along the 
south-trending faults in the southern part of the mountain. This conclusion is consistent with the 
potentiometric surface map that indicates that groundwater in this area probably flows from 
Crater Flat. 
6.5.3 Evaluation of Evidence for Local Recharge 
In this subsection, uranium-isotope ratio data (234U/238U activity ratios) are presented that 
indicate that local recharge is present in the saturated-zone waters beneath Yucca Mountain. 
This conclusion is further evaluated using data on the concentrations of major anions and 
cations.

ANL-NBS-HS-000021, REV 00 79 of 131 August 2000 
6.5.3.1 Description of Perched-Water Data 
Perched water was encountered in at least five boreholes at Yucca Mountain: USW UZ-14, USW 
NRG-7a, USW SD-9, USW SD-7, and USW WT-24. The perched-water samples were obtained 
by bailing or by pumping, depending on factors related to the drilling of the borehole. In 
general, it is believed that pumping produces a water sample more likely to represent in-situ 
chemical and isotopic conditions. Drilling has the potential to affect the chemical and isotopic 
composition of water in the borehole by putting foreign drilling fluids (generally air) into contact 
with the water in the borehole and, also, by grinding the rock and thereby exposing fresh, 
unaltered rock surfaces that may react with the water. If a water sample is bailed without first 
pumping the borehole to remove the water contacted by the drilling fluids and ground rock, the 
representativeness of the water sample of in-situ conditions is uncertain. By first purging the 
borehole of water present in the borehole at the time of drilling and drawing many borehole 
volumes of additional water from the formation into the borehole before sampling, confidence is 
gained that the water sample represents actual chemical conditions in the formation. 
Of the perched-water samples considered in this analysis, samples from boreholes SD-9 and 
NRG-7a (Table 7) were obtained exclusively by bailing (Yang and Peterman 1999, Table 19) 
during a hiatus in drilling following the encounter with the perched water. No pumping was 
done prior to sample collection at these boreholes. 
Perched-water samples from UZ-14 (Table 7) obtained prior to August 17, 1993, were obtained 
without first pumping the borehole. Pumped samples were obtained between August 17 and 
August 27, 1993, and an additional bailed sample was taken after pumping on August 31. A 
time series of delta strontium-87 (d87Sr) versus water production showed that d87Sr values 
continued to evolve until about 12,000 liters had been pumped from the borehole, or sometime 
after August 25 (Yang and Peterman 1999, Table 19, Fig. 113). Therefore, the d87Sr data, and 
perhaps other data, obtained from UZ-14 after this date probably best represent in-situ 
conditions. 
Perched water from borehole SD-7 sampled on March 8, 1995, was obtained by bailing prior to 
pumping. Perched-water samples obtained from borehole SD-7 between March 16 and March 
21, 1995, were obtained by pumping (Yang et al. 1996, p. 37). 
Perched water was sampled by pumping from borehole WT-24. However, according to 
Patterson et al. (1998, p. 277), the isotopic data obtained prior to the end of the 24-hour pumping 
test conducted on October 21 to 22, 1997, were collected during what the authors considered to 
be a clean-out period. 
In summary, the perched-water data are thought to represent in-situ conditions to varying 
degrees, depending on whether the samples were bailed or pumped and the extent to which the 
borehole was cleaned out prior to sampling. The data collected from borehole SD-7 on or after 
March 16, 1995, from borehole UZ-14 after August 25, 1993, and from borehole WT-24 on 
October 22, 1997, are thought to best represent the actual chemical and isotopic conditions of the 
perched water at Yucca Mountain. These samples are weighted more heavily than the remaining 
samples in developing the conclusions of this report.

ANL-NBS-HS-000021, REV 00 80 of 131 August 2000 
6.5.3.2 Evidence from 234U/238U Activity Ratios 
As a consequence of radioactive decay, 234U is preferentially enriched relative to 238U in 
migrating groundwater (Osmond and Cowart 1992, Fig. 9.1). The primary causes for this 
enrichment are the greater solubility of 234U due to radiation damage of crystal lattice sites 
containing 234U atoms (Szilard-Chalmers effect) and the greater probability that these 234U atoms 
have been converted to the more soluble uranyl ion due to the effects of radiation-induced 
ionization (Gascoyne 1992, section 2.5.1). In addition, decay of 238U can cause the displacement 
of the intermediate 234Th daughter (which rapidly decays to 234U) off of crystal surfaces into the 
adjacent water by alpha-recoil processes. The amount of excess 234U relative to 238U is 
controlled by 234U decay, water/rock ratios, flow-path length, uranium concentrations in the host 
rock, and the rate of rock dissolution in the aquifer. For this study, 234U decay is insignificant. 
Meteoric water (that is, precipitation) interacts with readily soluble soil components resulting in 
soil waters that contain relatively large amounts of both 234U and 238U derived by bulk 
dissolution (DTN: GS960908315215.013 and GS980908312322.009). Measured 234U/238U 
activity ratios in secondary minerals formed in soil zones on Yucca Mountain range from 1.4 to 
1.8 (DTN: GS960908315215.013 and GS980908312322.009). 
Pore waters extracted from core samples from the unsaturated zone at Yucca Mountain have 
234U/238U activity ratios that range from 1.5 to 3.0. Pore waters extracted from the top of the 
Paintbrush Tuff nonwelded hydrogeologic unit (PTn) have 234U/238U activity ratios of 1.5 to 2.5, 
whereas pore waters from the upper lithophysal unit of the welded Topopah Spring Tuff (Tpt) 
have 234U/238U activity ratios of 2.5 to 3.8 (DTN: GS991299995215.001, data set 
MOL.20000104.0007). These data suggest there is a general increase in 234U/238U activity ratios 
in pore waters from the soil zone down through the upper unsaturated zone. 
Analyses of 234U/238U activity ratios in perched-water samples range from 3.5 at borehole SD-7 
to 8.4 at borehole WT-24 (DTN: GS960908315215.013 and GS980108312322.003). The values 
at the high end of this range are unusual and suggest the existence of certain flow conditions. In 
particular, the high ratios are consistent with small intermittent fluxes of water passing through a 
fracture network. As a result of processes associated with alpha recoil during the decay of 238U, 
the 234U daughter product tends to be more readily mobilized than the parent 238U. In fractures 
that are not continuously or frequently flushed, these processes allow 234U to preferentially 
accumulate over time relative to 238U. When a small flux of water flows through such a fracture, 
it may preferentially incorporate 234U relative to 238U, resulting in water with an elevated 
234U/238U ratio. The accumulation of such small water fluxes could result in perched water with 
the observed high 234U/238U ratios. The changes to the 234U/238U activity ratios that would occur 
over time within the perched water are uncertain. Changes, if any, in the 234U/238U activity ratio 
of the perched water would depend on the 238U content of the host rock, the water volume to 
fracture-surface area (a function of fracture density and aperture), redox conditions, and other 
factors (Clark and Fritz 1997, pp. 238240). The 234U/238U activity ratio of the perched water 
might either increase or decrease with time, depending on the relative importance of these 
factors.

Table 7. Chemical and Isotopic Composition of Perched Water at Yucca Mountain 
Chemical Concentrations (mg L1) 
Water 
sample 
Depth 
(m) 
Sampling 
Method Date pH Ca Mg Na K Cl SO4 HCO3 SiO2 
13C 
() 
14C 
(pmc) 
3Ha,c 
(TU) 
dD 
() 
d18O 
() 
234U/238U 
Activity 
ratio 
36Cl/Cl 
(x 1015) 
479.76 Bailed 03-08-95  14.2 0.13 45.5 5.3 4.4 9.1 112 62.3 10.4 34.4 6.2 99.8 13.4  511 
488.29 Pumped 03-16-95 8.1 13.3 0.13 45.5 5.3 4.1 9.1 128 57.4 9.4 28.6  99.7 13.3   
488.29 Pumped 03-17-95 8.2 12.8 0.08 45.8 5.5 4.1 8.6 130 50.9 9.5 28.4  99.6 13.4 3.504 657 
488.29 Pumped 03-20-95 8.0 12.9 0.07 45.5 5.4 4.1 8.5 127 55 9.5 27.9  99.6 13.4 3.58  
SD-7 
488.29 Pumped 03-21-95 8.2 13.5 0.08 44.6 5.5 4.1 10.3 128 55.9 9.5 28.4 < 0.3 99.6 13.3 3.69 609, 635 
 Bailed 03-07-94          14.4 41.8 0 97.8 13.3   
 Bailed 07-07-94               2.42b
 
453.85 Bailed 07-17-94 8.6 2.9 0.2 98 9.8 5.6 27.6 197d 64.2 14.4 41.8 0 97.8 13.3  449 
SD-9 
 Bailed 09-12-94               2.42b
 
UZ-14 A 384.60 Bailed 08-02-93 7.6 23 1.8 39 5.6 7.9 14.3 150 34.2 10.2 41.7 0.3 98.6 13.8  559 
UZ-14 A2 384.60 Bailed 08-02-93 7.8 24 1.8 38 3.9 9.1 13.8 148.8 36.4 10.1 40.6 3.1 97.5 13.5  538 
UZ-14 B 387.68 Bailed 08-03-93 8.1 31 2.7 40 4.4 8.3 16.3 147.6 51.4 9.5 36.6 0 97.1 13.4  566 
UZ-14 C 390.75 Bailed 08-05-93 8.3 45 4.1 88 5.8 15.5 223 106.1 7.7 9.2 66.8 0.4 87.4 12.1  389 
UZ-14 PT-1 390.75 Pumped 08-17-93  37 3.1 40 6.3 7.2 57.3 144 21.4 9.8 32.3 1.8 97.8 13.3  644 
UZ-14 PT-2 390.75 Pumped 08-19-93  30 2.4 35 3.3 7.0 22.9 144 25.7  28.9 3.1 97.9 13.4  656 
UZ-14 PT-4 390.75 Pumped 08-27-93  27 2.1 34 1.8 6.7 14.1 141.5 32.1 9.6 27.2 0 97.3 13.4 7.56 675 
UZ-14 D 390.75 Bailed 08-31-93 7.8 31 2.5 35 4.1 7.0 24.2 146.4 40.7 11.3 29.2 0 97.6 13.1  690 
ANL-NBS-HS-000021, REV 00 81 of 131 August 2000

Table 7 (Continued). Chemical and Isotopic Composition of Perched Water at Yucca Mountain 
Chemical Concentrations (mg L1) 
Water 
sample 
Depth 
(m) 
Sampling 
Method Date pH Ca Mg Na K Cl SO4 HCO3 SiO2 
13C 
() 
14C 
(pmc) 
3Ha,c 
(TU) 
dD 
() 
d18O 
() 
234U/238U 
Activity 
ratio 
36Cl/Cl 
(x 1015) 
Pumped 10-06-97             99.6 13.4 4.36b  
Pumped 10-16-97               6.58b
 
Pumped 10-17-97               8.33  
WT-24e  
Pumped 10-22-97 8.1 23 1.4 37 2.4 9.0 16 135 46 11.8 29.6 <0.3 99.4 13.5 8.34 586 
 Bailed 03-04-94               5.17b
518 
460.25 Bailed 03-07-94 8.7 3 0 42 6.8 7 4 114 9 16.6 66.9 10 93.9 12.8  474 
NRG-7a 
 Bailed 03-08-94                 
DTN: GS980108312322.005 (ions, d13C, dD, d18O, 3H), GS950808312322.001 (3H), GS980108312322.003 (234U/238U activity ratios), GS991299992271.001 (3H), LAJF831222AQ98.011 
(36Cl/Cl), MO0007GNDWTRIS.003 (14C), MO0007GNDWTRIS.013 (d13C, dD, d18O, 14C), MO0007MAJIONPH.016 (chemistry) 
NOTES:  not available 
aTritium analyses have an accuracy of plus or minus 12 TU. 
bThese results are not representative of in-situ conditions due to sample contamination 
cThese data are included for reference only. 
dThis sample also contains 10 mg L1 CO3 
eAverage values of samples collected on October 22, 1997 
ANL-NBS-HS-000021, REV 00 82 of 131 August 2000

ANL-NBS-HS-000021, REV 00 83 of 131 August 2000 
As shown in Figure 18, saturated-zone waters also tend to have relatively high 234U/238U activity 
ratios compared to soil waters and unsaturated-zone pore waters at Yucca Mountain. 
Interestingly, waters from the shallow saturated zone beneath Yucca Mountain tend to have 
higher ratios than saturated-zone waters from adjacent areas (for example, Crater Flat, Fortymile 
Wash, and Highway 95; Figure 16). High 234U/238U activity ratios in saturated-zone waters from 
the area between the crest of Yucca Mountain and the eastern boundary of Busted Butte strongly 
suggest these waters contain a large perched-water component (Assumption 6 in Table 4). An 
attempt to quantify this proportion is presented in Section 6.5.6. 
DTN: GS930108315213.004, GS960208315215.001, GS960908315215.013, GS960908315215.014, 
GS970208315215.001, GS970208315215.002, GS970808315215.012, GS980108312322.003, 
GS980908312322.009 
Figure 18. Comparison of 234U/238U Activity Ratios in Saturated-Zone Waters to 
Ratios in Soil Waters and Unsaturated-Zone Pore Waters at Yucca Mountain

ANL-NBS-HS-000021, REV 00 84 of 131 August 2000 
6.5.3.3 Evidence from Other Chemical Constituents 
The concentrations measured for the major cations and anions in saturated-zone waters in the 
Yucca Mountain vicinity have proportions very similar to those found in perched waters, as 
shown in the trilinear diagram in Figure 19. The main differences in the major cation 
compositions of these waters involve calcium and magnesium. Perched waters have somewhat 
higher concentrations of these constituents than most saturated-zone waters at Yucca Mountain. 
This result could reflect the fact that saturated-zone waters have a high probability of coming in 
contact with zeolite minerals, which are known to have a high affinity for calcium and 
magnesium. In all, the major ion data for perched and saturated-zone waters are also consistent 
with the idea that the saturated-zone waters beneath Yucca Mountain contain a high proportion 
of perched water. 
6.5.4 Evaluation of Evidence for Timing of Recharge 
Hydrochemical data that potentially bear on the question of the age or timing of local recharge 
include hydrogen and oxygen isotope ratios and 14C radioactivities. Hydrogen and oxygen 
isotope ratios potentially contain age information because the numerical values of these ratios in 
groundwaters reflect the climate under which the waters were infiltrated. Therefore, if waters 
were recharged in a climatic regime different from the current regime, this fact should be 
reflected in the isotope ratios of the groundwaters. 
The activity of 14C in a particular groundwater sample potentially offers a more direct indication 
of the time at which that groundwater was recharged. In general, the older the sample, the lower 
the 14C activity. However, the interpretation of the age of a groundwater sample from 14C 
activity data is complicated by the fact that groundwaters can undergo soil/water/rock/gas 
interactions that can alter the proportions of carbon isotopes in a groundwater sample. This 
process, in turn, can lead to modification of the age calculated for the sample based on 14C 
activity as discussed further below. 
6.5.4.1 Evidence from Hydrogen and Oxygen Isotope Ratios 
Hydrogen and oxygen isotope ratios are useful for tracing groundwater movement where spatial 
differences in their concentrations exist that allow different parts of the groundwater system to be 
distinguished. Both hydrogen and oxygen are composed of more than one stable isotope. The 
stable hydrogen isotopes of interest here are 1H and 2H. The latter isotope is commonly referred 
to as deuterium with the chemical symbol D. The ratio of these two isotopes is measured and is 
generally reported in d notation as follows, with units of per mil: 
dD = [(D/1H)sample/(D/1H)standard  1] x 1000 (Eq. 1) 
The standard used for these measurements is known as Vienna Standard Mean Ocean Water 
(VSMOW) (Clark and Fritz 1997, p. 8).

ANL-NBS-HS-000021, REV 00 85 of 131 August 2000 
DTN: GS930108315213.002, GS950808312322.001, MO0007MAJIONPH.003, MO0007MAJIONPH.004, MO0007MAJIONPH.005, 
MO0007MAJIONPH.006, MO0007MAJIONPH.007, MO0007MAJIONPH.011, MO0007MAJIONPH.012, MO0007MAJIONPH.013, 
MO0007MAJIONPH.014, MO0008MAJIONPH.017 
NOTE: Open symbols are perched waters; closed symbols are groundwaters. 
Figure 19. Trilinear Diagram Comparing Compositions 
of Perched Waters and Saturated-Zone Groundwaters

ANL-NBS-HS-000021, REV 00 86 of 131 August 2000 
The stable oxygen isotopes of interest here are 16O and 18O. The ratio of these isotopes is 
measured and also reported in d notation as follows, with units of per mil: 
d18O = [(18O/16O)sample/(18O/16O)standard  1] x 1000 (Eq. 2) 
Vienna Standard Mean Ocean Water (VSMOW) is also used as the standard for oxygen isotope 
measurements (Clark and Fritz 1997, p. 8). 
The 2H and 18O atoms are part of the water molecule and, at low temperatures, are generally less 
affected by water/rock interactions than most major cations and anions. The values of dD and 
d18O in precipitation, fresh surface water, and groundwater are typically negative because of 
fractionation between the heavy and light isotopes of hydrogen and oxygen during evaporation 
over the initial moisture source area and because the residual water vapor becomes progressively 
more depleted in the heavier isotopes (2H and 18O) during successive precipitation events. A 
detailed discussion of all the processes affecting the isotopic composition of precipitation and 
recharge, and possible effects of water-rock interactions, is beyond the scope of this report. A 
summary of these processes is available in textbooks, such as Clark and Fritz (1997, Chps. 24, 
9). Some of the net effects of these processes are depicted in Figure 20. 
The values of dD and d18O in precipitation are strongly correlated on a global basis. This 
correlation has been termed the global meteoric water line. The equation for this line is dD = 8 
d18O + 10 (Clark and Fritz 1997, p. 36). The slope of the line is related to the ratio of the 
equilibrium fractionation factors for 2H and 18O, which is approximately 8.2 at 25C (Clark and 
Fritz 1997, p. 50). Locally, the isotopic composition of precipitation may follow a line with a 
somewhat different slope and intercept. Such lines have been referred to as the local meteoric 
water line. The deuterium excess is the intercept in the meteoric water line when the slope is 
8. This excess has been shown to be inversely related to the relative humidity of the air in the 
moisture source area (Clark and Fritz 1997, p. 45; Merlivat and Jouzel 1979, p. 5029). 
One of the primary factors affecting the isotopic composition of precipitation is condensation 
temperature, which is a function of season, elevation, and climate. Precipitation falling during 
periods when temperatures are low has more negative (depleted) dD and d18O values than 
precipitation falling during warm periods. Because average surface temperatures are correlated 
with elevation, precipitation falling at higher elevations tends to have more negative isotope 
ratios than precipitation falling at lower elevations. Late Pleistocene groundwater, identified by 
carbon-14 age dating or other techniques, is often more isotopically depleted compared to 
modern waters because it was recharged under conditions that were cooler than at present. Also, 
because of the inverse relation between the value for the deuterium excess and relative humidity 
of the moisture source areas, data for old groundwaters recharged during pluvial periods in the 
Pleistocene sometimes plot below the present-day global or local meteoric water line (Clark and 
Fritz 1997, pp. 198199, Fig. 8-2).

ANL-NBS-HS-000021, REV 00 87 of 131 August 2000 
DTN: N/A-reference only; Source: based on Clark and Fritz (1997, Figures 2-1, 2-9, 2-11, and 9-1) 
Figure 20. Effects of Different Processes on Delta Deuterium 
and Delta Oxygen-18 Composition of Subsurface Water 
Despite seasonal variations in the dD and d18O composition of precipitation, the isotopic 
composition of the recharge water in humid regions is generally close to the average volumeweighted 
isotopic composition of precipitation. In arid climates, the isotopic composition of the 
recharge can be substantially different from the average volume-weighted isotopic composition 
of precipitation because of the preferential recharge of winter precipitation (see, for example, 
Ingraham et al. 1991, p. 256) and because of evaporation prior to recharge. Generally, 
evaporation shifts the dD and d18O composition of the infiltrating water to the right of the 
meteoric water line. The slope of the evaporation line increases with increasing relative 
humidity of the air (Clark and Fritz 1997, Fig. 2-8). The slope of the evaporation line ranges 
between 3.9 and 4.5 for relative humidities between 0 and 50 percent, which encompasses the 
range of relative humidities typical of Yucca Mountain during the summer months. 
Once in the ground, interaction between groundwater and the solid surfaces in soil or rock can 
cause the d18O composition of groundwater to be shifted horizontally to the right of the meteoric 
water line. This interaction is facilitated by high temperatures such as those associated with 
known geothermal fields (Clark and Fritz 1997, pp. 250255). At low temperatures, these 
interactions are kinetically inhibited. However, under special circumstances, interactions 
between groundwater and silicate minerals, or between groundwater and subsurface gases, may 
cause the isotopic compositions of groundwater to be shifted to the left of the meteoric water line 
(Clark and Fritz 1997, Fig. 9-1). The special circumstances typically involve alteration of rock 
to clays at high rock/water ratios or, in the case of gases, proximity to gas vents associated with 
volcanoes. Note that hydrogen isotope ratios are not generally affected as much by water/rock

ANL-NBS-HS-000021, REV 00 88 of 131 August 2000 
interactions as oxygen isotope ratios because rocks generally contain much less hydrogen than 
water on a volume-to-volume basis. 
Many of the effects of seasonal and long-term temperature changes described in the preceding 
paragraphs have been reported for the Yucca Mountain area. Seasonal variations in the isotopic 
values of precipitation were reported by Ingraham et al. (1991, p. 248, Fig. 3) and by Benson and 
Klieforth (1989, Table 1a) for a number of sites at different elevations in the NTS vicinity. The 
average monthly volume-weighted d18O values of precipitation were shown by Ingraham et al. 
(1991, Figs. 3 and 4) to vary between about 14 per mil in March and April and 3 per mil in 
August. The d18O of springs discharging from perched water was generally shifted from the 
average volume-weighted d18O of precipitation toward the values typical of winter precipitation 
(Ingraham et al. 1991, Figs. 10 and 11), supportive of the concept that winter precipitation is 
preferentially recharged in arid regions. 
The effects of temperature differences associated with climate change may be evident in the data 
reported for Yucca Mountain groundwaters. Benson and Klieforth (1989, Fig. 11) noted a 
correlation between d18O values and the 14C age of groundwaters near Yucca Mountain. Waters 
are more depleted in 18O with increasing age between 9,000 and 18,500 yr ago, a trend they 
attributed to the colder temperatures existing at the time the older water was recharged. 
Variations in the d18O compositions of groundwater discharging in the Ash Meadows area at 
Devils Hole 55 km southeast of Yucca Mountain were preserved in calcites deposited between 
570,000 and 60,000 yr before the present (Winograd et al. 1992, Figs. 2 and 3). These variations 
were shown to correlate well with known glacial and interglacial episodes during the period of 
record, with d18O decreasing, on average, by 1.9 per mil during glacial periods. 
The dD and d18O values of regional groundwater samples and perched-water samples at Yucca 
Mountain are plotted in Figure 21. Also plotted in this figure is a local meteoric water line (dD = 
8 d18O + 8.9) as defined by Benson and Klieforth (1989, Fig. 14) from snow samples obtained 
from Yucca Mountain. Snow samples were used to define the local meteoric water line because 
these samples were less likely to be affected by evaporation than rain samples, especially 
samples of light summer rains that can have a substantial fraction of their volume evaporated 
before reaching the ground. 
The local groundwater data have been separated into two groups in terms of dD and d18O values. 
The first group is defined by samples from the northern Fortymile Wash area and includes 
samples from boreholes a#2, WT#15, JF#3, J-13, and J-12. Based on its chemical and isotopic 
characteristics, groundwater from borehole WT#14 seems to be associated with this group, 
despite its location approximately 1.8 km west of the Wash. This well will be included with the 
Fortymile Wash group of boreholes (Group 1) in subsequent discussions. Perched water samples 
have isotopic values similar to those of the low-dD saturated-zone samples in Group 1 (FMWN). 
The second group (Group 2) includes all the other saturated-zone water samples from the 
Yucca Mountain area. 
Group 1 samples have relatively heavy dD and d18O values compared to groundwater from other 
boreholes at Yucca Mountain and have relatively consistent dD values (excluding the a#2 
sample). The scatter in the data points within Group 1 probably reflects a combination of 
analytical errors and evaporation. The a#2 sample was obtained from upper Fortymile Canyon at 
a site of active recharge (Savard 1994, p. 1805). The relative enrichment of the dD and d18O

ANL-NBS-HS-000021, REV 00 89 of 131 August 2000 
values at borehole a#2 likely reflects the fact that this water is young and was recharged under 
current climatic conditions. The remainder of samples in Group 1 appear to have been infiltrated 
under slightly cooler climatic conditions than those reflected in the a#2 sample. However, the 
fact that these samples have heavier dD and d18O values compared to groundwaters in Group 2 
suggests Group 1 waters were infiltrated under warmer conditions than the prevailing conditions 
for Group 2 samples. 
DTN: GS000700012847.001, GS950808312322.001, GS970708312323.001, MO0007GNDWTRIS.002, MO0007GNDWTRIS.003, 
MO0007GNDWTRIS.005, MO0007GNDWTRIS.006, MO0007GNDWTRIS.007, MO0007GNDWTRIS.008, 
MO0007GNDWTRIS.009, MO0007GNDWTRIS.010, MO0007GNDWTRIS.012, MO0007GNDWTRIS.013, USGS (n.d.) (see 
assumption 23 in Table 4), (data are listed in Tables 3 and 7) 
NOTE: This figure has color-coded data points and should not be read in a black and white version. The solid line 
is the local meteoric water line from Benson and Klieforth (1989, Fig. 14). 
Figure 21. Delta Deuterium and Delta Oxygen-18 Data for 
Perched Water and Groundwater Near Yucca Mountain

ANL-NBS-HS-000021, REV 00 90 of 131 August 2000 
The samples in Group 2 come from wells west of Fortymile Wash on Yucca Mountain and in 
Crater Flat. The range in d18O for all the samples from the Yucca Mountain area is about 2 per 
mil, which is about the range in d18O expected between interglacial and glacial periods from the 
Devils Hole data (Winograd et al. 1992, Fig. 2). Therefore, the lightest (i.e., most negative) dD 
and d18O values shown in Figure 21 for samples from Group 2 are consistent with the hypothesis 
that the groundwaters they represent were infiltrated primarily during the late Pleistocene or 
early Holocene. Whether the range in dD and d18O values within Group 2 samples reflects 
infiltration under a range of climatic regimes or mixing of older and younger groundwaters 
cannot be resolved on the basis of dD and d18O values alone. 
6.5.4.2 Evidence from Carbon Isotope Data 
6.5.4.2.1 Carbon-14 Ages of Saturated-Zone Groundwaters 
Theoretically, the activity of 14C in a groundwater sample reflects the time at which the water 
was recharged. Unfortunately, precipitation waters are generally very dilute and have a high 
affinity for dissolution of solid phases in the soil zone, unsaturated zone, and/or saturated zone. 
In particular, in the transition from precipitation compositions to groundwater compositions, the 
bicarbonate + carbonate concentration in the water commonly increases by several orders of 
magnitude (Langmuir 1997, p. 292, Table 8.7). Because bicarbonate is the principal 14Ccontaining 
species in most groundwaters, the source of this additional bicarbonate can have a 
major impact on the age calculated from the 14C activity of a given water sample. If the source 
is primarily decaying plant material in an active soil zone, the calculated age for the water 
sample should be close to the real age. On the other hand, if the source of the bicarbonate is 
dissolution of old (. 104 yr) calcite with low 14C activity, the calculated age for the sample will 
be too old. 
A useful measure of the source of the carbon in a water sample is the d13C value of the sample 
because this value is different for organic materials compared to calcites. The d13C value is 
defined as follows, and expressed in units of per mil: 
d13C = [(13C/12C)sample/(13C/12C)standard  1] x 1000 (Eq. 3) 
The standard used for reporting stable carbon isotope measurements is carbon from a belemnite 
fossil from the Cretaceous Peedee formation in South Carolina (Clark and Fritz 1997, p. 9). 
The d13C values of carbon species typical of the soil waters in arid environments range from 25 
to 13 per mil (Forester et al. 1999, p. 36). At Yucca Mountain, pedogenic carbonate minerals 
have d13C values that generally are between 8 and 4 per mil, although early-formed calcites 
are also present that have d13C values greater than 0 per mil (Forester et al. 1999, Fig. 16; 
Whelan et al. 1998, Fig. 5). Paleozoic carbonate rocks typically have d13C values close to 0 per 
mil (Forester et al. 1999, Fig. 16; Whelan et al. 1998, Fig. 5). 
Values for d13C and 14C (in percent modern carbon, pmc) in perched waters and groundwaters 
from the Yucca Mountain area are plotted in Figure 22. Excluding the perched-water and the 
Fortymile Wash area (FMW-N) samples, the d13C and 14C values reported for the groundwater 
samples appear to be negatively correlated. In the absence of chemical reactions and/or mixing, 
waters moving from source areas to Yucca Mountain should experience no change in d13C but

ANL-NBS-HS-000021, REV 00 91 of 131 August 2000 
their 14C activity should decrease with time. If waters infiltrating into the source area had more 
or less constant d13C values, data points for waters infiltrated at different times would form a 
vertical trend in Figure 22. The fact that the data points in the figure do not form a vertical trend 
suggests either that the d13C of waters infiltrated at the source areas are not constant or that 
chemical reactions or mixing have affected the carbon isotope values. If waters that infiltrate 
into the source areas have randomly variable d13C ratios, then a random relation between d13C 
and 14C values would be expected. Rather the d13C and 14C values for Yucca Mountain and 
Crater Flat groundwaters are well correlated as shown in Figure 22. 
DTN: GS930908312323.003, GS950808312322.001, MO0007GNDWTRIS.002, MO0007GNDWTRIS.003, 
MO0007GNDWTRIS.005, MO0007GNDWTRIS.006, MO0007GNDWTRIS.007, MO0007GNDWTRIS.008, 
MO0007GNDWTRIS.009, MO0007GNDWTRIS.010, MO0007GNDWTRIS.012, MO0007GNDWTRIS.013, USGS (n.d.) (see 
assumption 23 in Table 4), (data are listed in Tables 3 and 7) 
NOTE: This figure has color-coded data points and should not be read in a black and white version. 
Figure 22. Carbon-14 Activity Versus Delta Carbon-13 of Perched 
Water and Groundwater Near Yucca Mountain 
It has been noted that d13C values in infiltrating waters reflect the types of vegetation present at 
the infiltration point. According to the data of Quade and Cerling (1990, p. 1550), the d13C of 
modern water infiltrated in cooler climates (for example, at higher elevations) is more negative 
than for modern water infiltrated in warmer climates (for example, at lower elevations). This 
relation would result in a positive correlation in Figure 22 because the older samples (that is,

ANL-NBS-HS-000021, REV 00 92 of 131 August 2000 
lowest pmc) plotted would tend to have the most negative d13C (that is, they infiltrated when the 
climate was cooler than it is now). Because the observed correlation in the groundwater values 
is negative instead of positive, the primary cause of the correlation must involve some other 
process(es). 
A likely cause of the negative correlation evident in Figure 22 is the dissolution of carbonate 
minerals such as calcite. For example, calcite with a d13C value of 4 per mil and a 14C activity 
of zero could readily explain the correlation if it were being dissolved by infiltrating soil waters. 
This explanation assumes that points on the regression line are of the same age but that the water 
dissolved different amounts of calcite. In this explanation, the scatter of points about the 
regression line could represent samples of slightly different ages. For example, dD and d18O 
data suggest that groundwaters from the northern part of Fortymile Wash (FMW-N) and the 
perched waters have younger ages than most Yucca Mountain groundwaters. This observation is 
consistent with the data plotted in Figure 22. 
The data points for water samples from drillhole a#2 are of particular interest because they 
represent recent infiltration (see below). As shown in the figure, the 14C activities in these two 
samples are only 60 and 62 pmc. This result suggests these samples obtained a significant 
fraction of their bicarbonate concentrations from a source with little or no 14C activity. 
Interestingly, these samples have lower d13C values than most groundwaters from the Yucca 
Mountain area. This result suggests the bicarbonate source was not calcite typical of the soil 
zone on Yucca Mountain as these have d13C values between 2 and 8 per mil (Whelan et al. 
1998, Fig. 5). 
To attempt to quantify the impact of calcite dissolution on ages calculated for groundwaters 
from Yucca Mountain, mass-balance calculations using the code NETPATH (Plummer et al. 
1994, pp. 2430) were carried out. For each groundwater sample, the initial water available to 
react with the rock and soil gas was assumed to be pure water that had equilibrated with 
atmospheric concentrations of CO2 (103.5 atm) (Assumption 16 in Table 4); therefore, the 
NETPATH models considered the net chemical changes in a water sample from the time it 
condensed as precipitation up until the time of sampling. The assumed values for the 14C 
activities (14A) of atmospheric CO2 (100 pmc) and of calcite and dolomite (0 pmc) (Assumption 
14) were combined with estimates of the amount of carbon contributed to the water sample by 
these phases to estimate the initial 14C activity of the samples prior to decay (14A0). The values 
of 14A0 were then used with the measured 14A of the water sample in the radioactive decay 
equation to determine the corrected 14C age of the groundwater. NETPATH returned two 
possible models for each groundwater sample, with and without the dissolution of pyrite and the 
formation of zeolite as a reaction product: 
Pure water + X1 calcite + X2 Ca2+/Na+ exchange + X3 CO2(g) + X4 NaCl + X5 gypsum + 
X6 dolomite + X7 glass + X8 SiO2 = groundwater + X9 zeolite + X10 clay (Model 1) 
Pure water + X1 calcite + X2 Ca2+/Na+ exchange + X3 CO2(g) + X4 NaCl + X5 gypsum + 
X6 dolomite + X7 glass + X8 SiO2 + X9 pyrite = groundwater + X10 clay. (Model 2) 
Each Xi represents the number of millimoles per liter of phase i dissolving into or precipitating 
out of solution or, in the case of Ca2+/Na+ exchange, sorbing or desorbing from the mineral 
surface. Because the models estimated that the amounts of pyrite dissolved and the amounts of 
zeolite and clay precipitated were small, the two models resulted in nearly identical corrected 14C

ANL-NBS-HS-000021, REV 00 93 of 131 August 2000 
ages. For brevity, only the results from the second model are given in Table 8. Dolomite, 
although not an important mineral phase in rocks above the carbonate aquifer, was assumed to be 
available to interact with the water as aeolian dust deposited at the land surface from dolomite 
outcrops located upwind of Yucca Mountain (Assumption 15 in Table 4). Although limited 
sampling has not confirmed the presence of Mg-bearing carbonates, such as dolomite, in dust at 
Yucca Mountain, the assumption of wind-blown dolomite dust as a source for Mg2+ is not 
expected to substantially affect the calculations because of the generally very low concentrations 
of Mg2+ in the groundwater. Gypsum and NaCl were assumed to have been available at the land 
surface as dust or as minerals precipitated from soil-zone water concentrated by 
evapotranspiration. Other minerals included in the model are known to be present in the tuffs at 
Yucca Mountain (Bish and Chipera 1989, Appendix A). 
The estimated values of 14A0 used to calculate the corrected ages are generally about 50 pmc 
(Table 8) because the reaction models estimated that approximately 50% of the carbon was 
derived from atmospheric CO2 with an assumed 14C activity of 100 pmc and 50% of the carbon 
was derived from either calcite or dolomite with an assumed 14C activity of 0 pmc (Assumption 
14). The 14C activity of calcite in the deep unsaturated zone and in the saturated zone is probably 
close to 0 pmc based on the distribution of 14C ages of calcite from the deep unsaturated zone 
(Whelan et al. 1998, Fig. 9). If shallow calcite dissolved by infiltrating water had a 14C activity 
similar to that of CO2 dissolved in the water, then no substantial dilution of the 14C activity of the 
water would result from calcite dissolution. The true values of 14A0 and the 14C ages of the 
groundwater samples may have been underestimated by the values in Table 8 because the 
NETPATH models assumed that all calcite had a 14C activity of 0 pmc; however, at least some of 
the calcite in the water samples probably originated from the soil zone where 14C activities are 
significantly nonzero. On the other hand, the effects of this assumption are partially 
counterbalanced by the assumption that all of the CO2 entered into solution in the soil zone 
where the 14C activity of the gas is probably near 100 pmc. If CO2 is dissolved deep in the 
unsaturated zone where the 14C activity of CO2 may be much less than 100 pmc (Yang et al. 
1996, Fig. 20), the corrected 14C ages would be erroneously old. 
The values of 14A0 from known recharge areas indicate that corrections to groundwater 14C ages 
are necessary but that the values of 14A0 may be slightly higher than indicated by Table 8 
(average 14A0 = 50  6 for 34 samples). Thomas et al. (1996, p. C51) reported that water samples 
from recharge areas in the central Spring Mountains and Sheep Range, west and north of Las 
Vegas, respectively, had bomb-pulse concentrations of tritium but were saturated with calcite 
and had 14C activities of 76 to 100 pmc. The presence of bomb-pulse tritium indicates that the 
14C activity of the water should also have contained a component of young water with 14C 
activities greater than 100 pmc because of elevated 14C activity in the atmosphere following 
atmospheric nuclear testing. Dilution of the 14C of recharge water by the dissolution of calcite is 
also indicated by data from samples from borehole a#2 in Fortymile Canyon, which had 14C 
activities of 60 and 62 pmc and tritium concentrations of 37 pCi L1 (12 TU) (DTN: 
MO0007GNDWTRIS.010). Water levels in boreholes adjacent to borehole a#2 have shown a 
rapid

Table 8. Results of NETPATH Corrections to Groundwater 14C Ages 
Sample mcalcite mCa/Na mCO2 mNaCl mgypsum mdolomite mglass
a mpyrite mSiO2 mclay
b d13C 14A 14A0 
Uncorrected 
14C agec (yr) 
Corrected 
14C agec (yr) 
J-12 0.664 0.672 1.240 0.206 0.209 0.167 0.335 0.010 0.041 0.159 7.9 32.2 55.9 9,368 4,565 
J-13 0.799 0.763 1.205 0.200 0.157 0.125 0.329 0.010 0.108 0.156 7.3 29.2 54.0 10,176 5,085 
b#1(bh) 1.016 0.845 1.255 0.240 0.215 0.051 0.230 0.007 0.277 0.109 10.55 16.7 53.4 14,795 9,607 
b#1(Tcb) 1.067 0.867 1.302 0.211 0.208 0.051 0.184 0.006 0.461 0.087 8.6 18.9 53.2 13,772 8,551 
c#1 1.115 1.094 1.367 0.209 0.232 0.029 0.131 0.004 0.596 0.062 7.1 15.0 54.3 15,683 10,633 
c#2 1.107 1.053 1.138 0.200 0.221 0.033 0.138 0.004 0.546 0.066 7.0 16.6 49.8 14,845 9,085 
c#3 1.105 1.076 1.110 0.203 0.223 0.031 0.125 0.004 0.563 0.059 7.5 15.7 49.3 15,306 9,465 
p#1(v) 1.878 1.762 4.377 0.367 0.374 0.454 0.368 0.011 0.126 0.175 4.2 3.5 61.2 27,713 23,659 
p#1(c) 1.973 2.749 10.612 0.791 1.620 1.698 0.789 0.024 1.337 0.375 2.3 2.3 66.5 31,184 27,802 
a#2(dp) 0.803 0.791 1.121 0.310 0.225 0.017 0.072 0.002 0.547 0.034 13.0 62.3 57.8 3,912 0d 
a#2(sh) 0.838 0.820 1.224 0.248 0.214 0.022 0.085 0.003 0.514 0.041 13.1 60.0 58.6 4,223 0d 
G-4 1.254 1.136 1.015 0.166 0.190 0.024 0.138 0.004 0.396 0.066 9.1 22.0 44.4 12,517 5,808 
H-1(Tcp) 0.925 1.005 0.946 0.161 0.178 0.022 0.158 0.005 0.379 0.075  19.9 50.0 13,346 7,621 
H-1(Tcb) 0.964 1.011 1.088 0.164 0.192 0.016 0.105 0.003 0.397 0.050 11.4 23.9 52.8 11,832 6,547 
H-3 2.219 2.522 1.686 0.155 0.319 0.009 0.072 0.002 0.531 0.034 4.9 10.5 43.3 18,631 11,721 
H-4 1.606 1.465 1.340 0.195 0.260 0.032 0.171 0.005 0.329 0.081 7.4 11.8 45.0 17,666 11,066 
H-5(sample 1) 1.078 1.198 0.950 0.172 0.158 0.016 0.138 0.004 0.446 0.066 7.4 18.2 46.8 14,084 7,800 
H-5(sample 2) 1.081 1.198 0.964 0.172 0.158 0.016 0.138 0.004 0.446 0.066 10.3 21.4 47.1 12,745 6,514 
H-6(bh) 1.547 1.751 1.368 0.214 0.297 0.014 0.085 0.003 0.581 0.041 7.5 16.3 46.9 14,996 8,745 
H-6(Tct) 1.574 1.800 1.862 0.203 0.255 0.011 0.085 0.003 0.564 0.041 7.3 10.0 54.2 19,035 13,971 
H-6(Tcb) 1.577 1.796 2.134 0.209 0.328 0.014 0.092 0.003 0.580 0.044 7.1 12.4 57.4 17,256 12,665 
VH-1(sample 3) 1.265 1.538 1.356 0.282 0.451 0.075 0.118 0.004 0.513 0.056 8.5 12.2 49.4 17,391 11,562 
WT#14 0.800 0.813 1.183 0.231 0.209 0.071 0.329 0.010 0.108 0.156 12.7 24.1 56.2 11,763 7,000 
WT#15 1.196 1.133 1.450 0.339 0.148 0.105 0.302 0.009 0.109 0.144 11.8 21.6 51.2 12,668 7,136 
G-2 0.872 0.855 1.075 0.183 0.135 0.060 0.348 0.010 0.042 0.166 11.8 20.5 52.6 13,101 7,791 
WT-10 1.634 1.924 1.567 0.220 0.350 0.011 0.072 0.002 0.598 0.034 6.2 7.3 49.0 21,636 15,742 
WT#12 1.370 1.300 1.397 0.220 0.281 0.032 0.171 0.005 0.345 0.081 8.1 11.4 49.8 17,951 12,188 
ANL-NBS-HS-000021, REV 00 94 of 131 August 2000

Table 8 (continued). Results of NETPATH Corrections to Groundwater 14C Ages 
Sample mcalcite mCa/Na mCO2 mNaCl mgypsum mdolomite mglass
a mpyrite mSiO2 mclay
b d13C 14A 14A0 
Uncorrected 
14C agec (yr) 
Corrected 
14C agec (yr) 
JF#3 0.604 0.596 1.009 0.282 0.277 0.196 0.585 0.018 0.564 0.278 8.6 30.7 51.0 9,762 4,189 
WT-17 0.954 0.949 1.128 0.181 0.172 0.055 0.171 0.005 0.212 0.081 8.3 16.2 52.0 15,047 9,647 
WT#3 0.989 0.942 1.208 0.169 0.175 0.071 0.256 0.008 0.280 0.122 8.2 22.3 52.2 12,405 7,025 
UZ-14(Tcp) 1.274 1.409 0.798 0.189 0.138 0.015 0.125 0.004 0.413 0.059 14.1 24.6 38.7 11,593 3,745 
UZ-14(Tcb) 1.340 1.482 0.794 0.217 0.138 0.016 0.125 0.004 0.463 0.059 14.4 21.1 37.4 12,862 4,731 
16S/49E-5acc 0.986 0.624 0.988 0.169 0.250 0.130 0.342 0.010 0.158 0.162 7.1 19.3 44.8 13,599 6,969 
15S/49E-22dcc 0.995 0.737 1.211 0.214 0.325 0.121 0.312 0.009 0.017 0.148 10.2 15.6 50.0 15,359 9,632 
DTN: GS930108315213.002, GS930908312323.003, GS950808312322.001, MO0007GNDWTRIS.002, MO0007GNDWTRIS.003, MO0007GNDWTRIS.007, 
MO0007GNDWTRIS.009, MO0007GNDWTRIS.010, MO0007GNDWTRIS.011, MO0007MAJIONPH.003, MO0007MAJIONPH.005, MO0007MAJIONPH.006, 
MO0007MAJIONPH.011, MO0007MAJIONPH.012, MO0007MAJIONPH.013, MO0007MAJIONPH.014, (input data for major ions are listed in Table 3) 
DTN (output data): LA0006EK12213S.001 
aGlass composition was defined as: K0.402Na0.368Ca0.023Fe(3+)0.026Al0.7826Si4.190O10.0 (Broxton et al. 1987, Table 3, Topopah Spring Member). 
bClay composition was defined as: K0.027Na0.127Ca0.164Mg0.245Fe(3+)0.1186Al1.646Si3.434O10.0. 
cCarbon-14 age was calculated from tyears = 8266.6 ln(14A0/14A), where 14A0 = 100 pmc for the uncorrected ages and 14A0 was determined by NETPATH for the corrected 14C ages. 
Corrected ages are based on Assumptions 14, 15, 16 and 17 in Table 4. 
dThe NETPATH model calculated a negative 14C age for this sample. 
ANL-NBS-HS-000021, REV 00 95 of 131 August 2000

ANL-NBS-HS-000021, REV 00 96 of 131 August 2000 
response to runoff events in the wash (Savard 1994, p. 1805), and recent water samples from 
borehole a#2 have bomb-pulse levels of chlorine-36 (DTN: LAJF831222AQ98.011), providing 
confirmation that borehole a#2 is located in an area of active recharge. A number of lines of 
evidence therefore indicate that, although the 14C activities of groundwater near Yucca Mountain 
require corrections for the effects of calcite dissolution, the actual value of 14A0 in some cases 
may have been underestimated by the NETPATH models. The effect of using a different 14Ao in 
calculating 14C ages is shown in Table 9 for samples with various pmc values. The true 14C ages 
for groundwater samples from the volcanic units probably are between the uncorrected 14C ages 
and the corrected 14C ages calculated, assuming 14A0 is 50 pmc. 
Table 9. Calculated 14C Ages for Different Assumed Values of Initial 14C Activity (14A0) 
Measured 14C Activity 
(pmc) 
14C Age Using 14A0 = 100 pmc 
(yr) 
14C Age Using 14A0 = 65 pmc 
(yr) 
14C Age Using 14A0 = 50 pmc 
(yr) 
5 24,765 21,204 19,035 
10 19,035 15,474 13,305 
15 15,683 12,122 9,953 
20 13,305 9,744 7,575 
25 11,460 7,899 5,730 
30 9,953 6,392 4,223 
35 8,679 5,117 2,949 
40 7,575 4,014 1,845 
45 6,601 3,040 871 
50 5,730 2,169 modern 
55 4,942 1,381 modern 
60 4,223 662 modern 
65 3,561 modern modern 
70 2,949 modern modern 
75 2,378 modern modern 
DTN: N/A 
In general terms, the 14C ages calculated for groundwaters in the vicinity of Yucca Mountain are 
youngest in the northeast (i.e., borehole a#2) and increase to the south-southwest and southwest 
across Yucca Mountain into Crater Flat. The uncorrected ages increase from approximately 
4,000 yr in the northeast to approximately 21,000 yr (borehole WT-10) in the southwest. Ages 
corrected on the basis of NETPATH calculations including the dissolution of calcite with zero 
14C activity range from 0 yr in the northeast (borehole a#2) to approximately 15,000 yr in the 
southwest (borehole WT-10). 
The 14C ages of groundwater samples from wells in or near Fortymile Wash are younger than the 
ages of groundwaters beneath Yucca Mountain and Crater Flat. The uncorrected ages range 
from approximately 4,000 yr in the north (borehole a#2) to approximately 10,000 yr in the south 
(borehole JF#3). Corrected ages range from 0 yr in the north (borehole a#2) to approximately 
4,100 yr in the south (borehole JF#3). The sample from well J-13 has slightly older uncorrected 
and corrected ages (Table 8).

ANL-NBS-HS-000021, REV 00 97 of 131 August 2000 
In all, the 14C age calculations suggest groundwaters beneath Yucca Mountain were recharged 
between 6,000 and and 19,000 yr ago depending on whether corrected or uncorrected ages are 
used. The dD and d18O data are consistent with recharge of these waters during cooler climates 
than exist in the region today and have existed for approximately the last 10,000 yr. Therefore, 
the data favor recharge ages between approximately 10,000 and 19,000 yr for groundwaters 
beneath Yucca Mountain and southern Crater Flat. The groundwaters in Fortymile Wash have 
ages that range from modern to approximately 10,000 yr. Therefore, these waters were 
recharged more recently than most groundwaters beneath Yucca Mountain. This conclusion is 
consistent with the available dD and d18O data, which suggest groundwaters in Fortymile Wash 
(except borehole a#2) were recharged during climates that were cooler than the modern climate 
but warmer than the climate under which the groundwaters beneath Yucca Mountain were 
recharged. 
A comparison of the 14C ages of the dissolved inorganic and dissolved organic carbon in 
groundwater from the regional carbonate aquifer has indicated that isotope exchange needs to be 
considered in addition to dissolution of calcite or dolomite when correcting the 14C ages of the 
dissolved inorganic carbon in the carbonate aquifer (Thomas 1996, pp. 95101). Isotope 
exchange was not considered in applying NETPATH to groundwater samples from the carbonate 
aquifer at borehole p#1 (Assumption 17) and, therefore, the 14C ages listed in Table 8 for 
samples from borehole p#1 probably overestimate the true ages. Reaction models that included 
isotope exchange resulted in a range of corrected 14C ages that included some ages less than 
10,000 yr. As originally reported by Thomas (1996, pp. 95101), the magnitude of the age 
correction was very sensitive to the amount of carbon assumed to be contributed by isotope 
exchange and the assumed d13C of the carbonate exchanging with the groundwater. 
6.5.4.2.2 Carbon-14 Ages of Perched Waters 
The same reaction models and assumptions used to correct the 14C ages of the groundwater 
samples from the regional flow system were also used to correct the 14C ages of some of the 
perched-water samples reported in Table 7. The corrected 14C ages of the selected perched-water 
samples, including those from boreholes SD-7 and UZ-14, were generally less than 5,000 yr. 
However, other observations indicate that the 14C ages of the perched-water samples do not 
require substantial correction for the dissolution of carbonate. First, the ratios of chlorine-36 to 
stable chlorine (36Cl/Cl) of the perched-water samples were similar to those expected for their 
uncorrected 14C age, based on reconstructions of 36Cl/Cl ratios in precipitation throughout the 
late Pleistocene and Holocene from pack-rat midden data (Plummer et al. 1997, Fig. 3; DTN: 
LAJF831222AQ97.002, GS950708315131.003 and GS960308315131.001). Second, Winograd 
et al. (1992, Fig. 2) presented data from calcite deposits that indicated the d18O values in 
precipitation during the Pleistocene were, on average, 1.9 per mil more depleted during pluvial 
periods compared to interpluvial periods. The d18O values of the perched-water samples 
generally are more depleted than pore-water samples from the shallow unsaturated zone at Yucca 
Mountain by more than 1.0 per mil (Figure 23). This consistent difference suggests that, at some 
boreholes, the perched water may contain a substantial component of water from the Pleistocene. 
The lack of agreement between the corrected 14C age determined for the perched-water samples 
from the NETPATH model and the greater age indicated by the 36Cl/Cl and d18O data may have

ANL-NBS-HS-000021, REV 00 98 of 131 August 2000 
DTN: GS000700012847.001, GS950808312322.001, MO0007GNDWTRIS.002, MO0007GNDWTRIS.003, 
MO0007GNDWTRIS.005, MO0007GNDWTRIS.006, MO0007GNDWTRIS.007, MO0007GNDWTRIS.008, 
MO0007GNDWTRIS.009, MO0007GNDWTRIS.010, MO0007GNDWTRIS.012, MO0007GNDWTRIS.013, 
USGS (n.d.) (see assumption 23 in Table 4), (data are listed in Tables 3 and 7) 
NOTE: This figure has color-coded data points and should not be read in a black and white version. 
Figure 23. Delta Deuterium and Delta Oxygen-18 Data for Borehole UZ-14 Unsaturated-Zone 
Pore Water, Perched Water, and Groundwater Near Yucca Mountain 
resulted from erroneous assumptions in the NETPATH model regarding the 14C activity of soilzone 
calcites; the NETPATH model assumes the soil-zone calcite was completely depleted in 
14C (Assumption 14). Another possible reason for underestimated values of 14A0 is that the massbalance 
approach does not account for the increase in Ca2+ and Mg2+ due to evapotranspiration of 
precipitation, an increase that was then erroneously attributed to the dissolution of calcite or 
dolomite (Assumption 16). In summary, it is tentatively concluded that the uncorrected 14C ages 
of the perched water calculated from their measured 14C activities approximate their true 14C 
ages. Based on the 14C activities of perched-water samples in Table 7 and assuming 14A0 equals 
100 pmc, the 14C ages of the perched-water samples are generally between 7,000 and 11,000 yr, 
although the single sample from borehole NRG-7a and one of several samples from UZ-14 had 
much younger 14C ages of about 3,300 yr.

ANL-NBS-HS-000021, REV 00 99 of 131 August 2000 
In summary, the available 14C, dD, and d18O data for perched waters suggest these waters are 
older and were infiltrated during climates that were cooler than those under which the shallow 
unsaturated-zone pore waters were infiltrated. 
6.5.5 Evaluation of Evidence for Mixing Relations Between Waters from Different 
Sources 
6.5.5.1 Evaluation of Evidence for Mixing Relations Between Perched Waters at Yucca 
Mountain and Upgradient Groundwaters 
Although it may seem that establishing whether or not mixing is an important process in the 
Yucca Mountain flow system should be a relatively simple matter, this turns out not to be the 
case. The problem is that groundwater compositions of mixing end members are not unique and 
are not constant. That is, instead of there being a limited number of well-defined compositions 
that mix to form other compositions, the factors that determine groundwater compositions are 
continuously variable even for conservative constituents. The processes that determine the 
concentrations of major constituents in groundwaters such as those present at Yucca Mountain 
include the following: 
1. The composition of precipitation 
2. Evapotranspiration 
3. Precipitation or dissolution of solid phases in the soil zone, the unsaturated zone, or the 
saturated zone 
4. Interaction of waters with the solid phases in soils and rocks (e.g., leaching, sorption) 
5. Interaction of waters with any gas phases present (e.g., CO2 and carbonic acid) 
6. Mixing of waters of different compositions. 
To determine whether or not mixing (6) has influenced the composition of a given groundwater, 
the effects of the other five processes listed above must be independently known or quantifiable. 
The most likely constituents for which this might be possible are conservative constituents such 
as chloride. This possibility results from the following facts: 
a) Chloride minerals involving the major cations are highly soluble. Therefore, 
precipitation of a solid phase is generally not a factor in determination of the chloride 
concentration in groundwaters. 
b) The aquifer host rocks generally are not a significant source of chloride ions. That is, the 
concentration of chloride ions in groundwaters are generally not changed by additions 
from the host rocks, particularly if those host rocks are volcanic rocks at near-surface 
temperatures (Assumption 9 in Table 4). Factors (a) and (b) combined eliminate factor 
(3) above from further consideration.

ANL-NBS-HS-000021, REV 00 100 of 131 August 2000 
c) Chloride ions do not have much affinity for the solid surfaces present in aquifers. 
Therefore, chloride ions that are in the water stay in the water. Factors (b) and (c) 
eliminate factor (4) above from further consideration. 
d) The chloride ion is not a volatile species when dissolved in water at ambient 
temperatures. Therefore, once dissolved in water, chloride ions do not tend to become 
enriched in any gas phase that may be present. This fact eliminates factor (5) above from 
further consideration. 
If it can be assumed for the sake of argument, that precipitation compositions are adequately 
known or can be obtained (Assumptions 10 and 12), factor (1) can be eliminated from further 
consideration. This result leaves factors (2) and (6) as independent variables. If the amount of 
evapotranspiration associated with a given groundwater composition could be independently 
determined, then, under certain conditions, mixing relations for groundwaters could be 
determined from the concentrations of conservative species. Unfortunately, the amount of 
evapotranspiration represented by a given groundwater composition is commonly inferred from 
the concentrations of conservative species in the waters. This fact precludes the use of 
conservative species in the definition of mixing relations unless the amount of evapotranspiration 
can be independently determined. This determination is usually difficult to do. 
One case in which conservative species may allow the definition of mixing relations is the 
situation in which the number of waters that are mixing is known and there are a sufficient 
number of conservative species with a sufficient range of concentrations to determine the 
proportions of each groundwater in the mixture. A possible example of this case could be that in 
which local recharge at Yucca Mountain mixes into the underflow coming from upgradient 
sources. Both the recharge water and the underflow water must have well defined and different 
concentrations of conservative constituents for meaningful mixing relations to be derived. The 
chloride concentrations in perched waters and groundwaters upgradient of Yucca Mountain (e.g., 
borehole H-6) show similar ranges (Table 3). Therefore, chloride concentrations cannot be used 
to define mixing relations for these waters. 
Other conservative constituents (e.g., SO4
2, F, U6+, As, Se, dD, and d18O) may show greater 
differences in concentrations between perched and upgradient groundwaters at Yucca Mountain 
and could be used to define mixing relations. For example, if it could be determined that 
uranium was a conservative constituent in Yucca Mountain perched and groundwaters, a strong 
candidate for a method to derive the desired mixing proportions would be one involving 
234U/238U activity ratios and uranium concentrations. For this method to be viable, the uranium 
activity ratios in each component would have to be different (and separately constant). The 
uranium concentrations of the two components could either be the same value or two different 
values. However, the concentrations must be constant and measurable for each component. 
Unfortunately, the hydrochemical database currently available for the Yucca Mountain area is 
inadequate to test mixing relations of this type.

ANL-NBS-HS-000021, REV 00 101 of 131 August 2000 
6.5.5.2 Implications of Chloride and Deuterium Data for Mixing Between the Carbonate 
and Volcanic Aquifers 
To evaluate the question of upwelling of water from the carbonate aquifer into the volcanic units, 
Cl concentrations were plotted as a function of dD (Figure 24). Chloride and dD were chosen to 
investigate possible mixing relations because these constituents are relatively conservative once 
in the groundwater. As the figure shows, groundwater samples from the volcanic units have 
variable dD values that encompass the dD value of groundwater from the carbonate aquifer, 
represented by the sample p#1(c). The absence of a large contrast in the dD of groundwater in 
the volcanic and carbonate aquifers is, in itself, inconclusive with regards to mixing because the 
dD value of two unrelated groundwaters can be similar if the climate under which recharge 
occurred was similar. As discussed in the following paragraphs, the large contrast between the 
Cl concentrations of groundwater in the carbonate and volcanic aquifers is far more diagnostic 
with regard to the extent of mixing between the two aquifers. 
Groundwaters in the volcanic units have some variability in Cl- concentrations, but most of this 
variability is confined to areas bordering Yucca Mountain in Crater Flat (samples VH-1 and VH- 
2), the southern edge of Crater Flat (samples NC-EWDP-1D, NC-EWDP-9S, and NC-EWDP- 
3D), or Fortymile Wash (samples WT-15, JF-3 and 29a#2). Except for sample p#1(v), the 
groundwater samples in the volcanic aquifer at Yucca Mountain itself have relatively uniform 
Cl concentrations of approximately 0.2 mmol L1 (7 mg L1). The higher Cl- concentration of 
the p#1(v) sample can be explained by mixing between groundwater from the carbonate and 
volcanic aquifers within the borehole. It is estimated from flow logs that the p#1(v) sample 
received about 28.6 percent of its water from the carbonate aquifer as a result of upward flow in 
the borehole, despite an attempt to isolate the volcanic and carbonate aquifers from each other 
with a temporary plug (Craig and Robison, 1984, p. 49). 
The data for sample p#1(c) indicate that groundwater in the carbonate aquifer at Yucca Mountain 
has a Cl concentration nearly four times as high (0.79 mmol L1, or 28 mg L1) as that typical 
for groundwaters in the volcanic aquifer. The representativeness of the Cl- concentration data for 
the carbonate aquifer at p#1 was assessed by comparing these data with the Cl concentrations of 
major springs discharging from the carbonate aquifer in Ash Meadows. The Cl- concentrations at 
Ash Meadows ranged from 0.59 to 0.76 mmol L1 and had a discharge-weighted average of 0.66 
mmol L1 (Winograd and Pearson, 1976, Table 1). Although the Cl concentrations of 
groundwater at p#1 are slightly higher than the groundwater discharging at Ash Meadows, the 
data for the carbonate aquifer from these two areas are consistent and support the contention that 
the groundwater in the carbonate aquifer at Yucca Mountain has a much higher Cl concentration 
than groundwater in the volcanic aquifer. 
The large contrast in Cl concentrations between the volcanic and carbonate aquifers indicates 
that, unless all the volcanic aquifer water samples were uniformly affected by water from the 
carbonate aquifer, groundwaters in the volcanic units beneath Yucca Mountain contain, at most, 
only a minor amount of water from the carbonate aquifer. A uniform response of groundwater 
Cl concentrations in the volcanic aquifer to upwelling from the carbonate aquifer seems 
unlikely, however, given the variable depths of the groundwater samples and the variability in 
other chemical and isotopic constituents. The conclusion that upwelling of groundwater from the 
carbonate aquifer into the volcanic aquifer is minor does assume that the Cl concentration of

ANL-NBS-HS-000021, REV 00 102 of 131 August 2000 
groundwater sample p#1(c) is representative of the carbonate aquifer in the vicinity of Yucca 
Mountain (Assumption 11). 
DTN: GS000700012847.001, GS950808312322.001, GS970708312323.001, MO0007GNDWTRIS.002, MO0007GNDWTRIS.003, 
MO0007GNDWTRIS.005, MO0007GNDWTRIS.006, MO0007GNDWTRIS.007, MO0007GNDWTRIS.008, 
MO0007GNDWTRIS.009, MO0007GNDWTRIS.010, MO0007GNDWTRIS.011, MO0007GNDWTRIS.012, 
USGS (n.d.) (see assumption 23 in table 4), (data are listed in Tables 3 and 7) 
NOTE: This figure has color-coded data points and should not be read in a black and white version. 
Figure 24. Chloride Versus Delta Deuterium of Groundwater Near Yucca Mountain 
Fridrich et al. (1994, p. 157) hypothesized that the Solitario Canyon Fault could be a conduit for 
upwelling of water from the carbonate aquifer into the volcanic units overlying it. The 
groundwater samples obtained near the Solitario Canyon Fault (boreholes H-3, H-5, H-6, 
WT-10) have low Cl concentrations suggesting that they contain little water from the carbonate 
aquifer (Figure 24). Because the dD contents of groundwater near Fortymile Wash and water 
from the carbonate aquifer are very different (Figure 24), the slightly elevated Cl concentrations 
of some groundwater samples from the Fortymile Wash area compared to wells on Yucca 
Mountain were probably not caused by groundwater mixing between the carbonate and volcanic 
aquifers.

ANL-NBS-HS-000021, REV 00 103 of 131 August 2000 
6.5.6 Evaluation of Evidence for the Magnitude of Recharge at Yucca Mountain 
The magnitude of recharge at Yucca Mountain is estimated in this section on the basis of the 
concentrations of constituents such as chloride that are considered conservative in groundwater 
systems of the type present at Yucca Mountain (Assumption 9). In particular, the Cl mass 
balance (CMB) method will be used for this purpose. This method is based on the premise that 
the flux of Cl deposited at the surface equals the flux of Cl carried beneath the root zone by 
infiltrating water. With increasing depth in the root zone, Cl concentrations in soil waters 
increase and apparent infiltration rates decrease as water is extracted by the processes of 
evapotranspiration (Figure 25). However, once soil waters move below the zone of 
evapotranspiration, they become net infiltration and their Cl concentrations are assumed to 
remain constant. It is these Cl concentrations that are used to calculate net infiltration rates and 
ultimately, recharge rates. 
The CMB method uses the following equation to calculate the infiltration rate (I): 
I = (P C0)/Cp (Eq. 4) 
where P is average annual precipitation, C0 is average Cl concentration in precipitation, 
including the contribution from dry fallout, and Cp is the measured Cl concentration in 
groundwaters. The CMB method (Figure 25) assumes one-dimensional, downward piston flow, 
constant average annual precipitation rate, constant average annual Cl deposition rate, no run-on 
or run-off, no Cl source other than precipitation (e.g., it is assumed that the concentrations of Cl 
brought in by surface runoff and Cl released from weathering of surface rocks are negligible), 
and no Cl sink. 
Estimates of recharge using the CMB technique for 15 groundwater basins in Nevada were found 
to be in fairly good agreement with estimates obtained by the Maxey-Eakin linear step function 
(Dettinger 1989, p. 75). Using a 6-year study of two upland basins selected as analog wetter 
climate sites for Yucca Mountain, Lichty and McKinley (1995, p. 1) showed the CMB method to 
be more robust than a water-balance modeling approach using a deterministic watershed model 
for estimating basin-wide recharge for two comparatively wet sites in the Kawich Range north of 
Yucca Mountain. They attributed the robustness of the CMB method to the small number of 
measured parameters required as compared to the number of parameters needed for defining a 
deterministic watershed model.

ANL-NBS-HS-000021, REV 00 104 of 131 August 2000 
DTN: N/Areference only 
Note: Part (a) illustrates the underlying basis of the CMB method. Part (b) shows prorewater Cl concentrations as 
a function of infiltration, assuming a range of chloride deposition rates (106 to 183 mg porewater Cl m2 yr-1). 
Assuming an average annual precipitation rate of 170 mm, these deposition rates correspond to effective Cl 
concentrations of 0.62 mg L1 to 1.07 mg L1 in local precipitation. 
Figure 25. Chloride Mass Balance Method for Estimating Infiltration 
Point estimates of net infiltration or recharge using the CMB method tend to be less robust than 
basin-wide estimates because of additional assumptions concerning vertical groundwater flow 
and surface water flow. Conditions under which these assumptions may not be valid at Yucca 
Mountain are discussed in another AMR (CRWMS M&O 2000, section 6.9.2.2). The 
applicability of the CMB method to the specific conditions at Yucca Mountain (e.g., fractured 
rock) is an assumption to be verified (TBV) (Assumption 13). Another TBV assumption is that 
the annual deposition rate for chloride is known and constant for present-day conditions as well 
as over the long-term past (Assumption 12). Values of net infiltration estimated at Yucca 
Mountain using the CMB method range from less than 0.5 mm yr1 in washes to a maximum of 
nearly 20 mm yr1 beneath ridgetops and sideslopes (based on data and calculations in DTN: 
LA0002JF831222.001, LA0002JF831222.002, LA9909JF831222.010, LA9909JF831222.012; 
CRWMS M&O 2000, Sec. 6.9.2.4), depending on the Cl deposition rate assumed in the 
calculation.

ANL-NBS-HS-000021, REV 00 105 of 131 August 2000 
Table 10 lists recharge rates calculated from measured groundwater Cl concentrations using the 
CMB method. This method requires that the Cl deposition rate, which is the product of 
precipitation and effective Cl concentration in precipitation (including both wet and dry fallout), 
be known. The average annual precipitation rate for Yucca Mountain is 170 mm (Hevesi et al. 
1992, p. 677), and estimates of average Cl concentrations in precipitation at Yucca Mountain 
range from 0.3 to 0.6 mg L1 (CRWMS M&O 2000, Sec. 6.9.2.3). To bound the recharge rate 
estimates, Rate 1 in Table 10 is calculated using the lower estimate for Cl concentration whereas 
Rate 2 is calculated using the higher estimate. The CMB recharge estimates average 7  1 mm 
yr1 for Rate 1, and 14  2 mm yr1 for Rate 2 (Table 10). The much narrower range of fluxes 
estimated for the saturated zone samples compared to the unsaturated zone samples can probably 
be attributed to the greater volume averaging of the saturated-zone samples, as well as to mixing 
in the aquifer and in the borehole when the saturated-zone samples were pumped. 
Table 10. Recharge Rates Based on the Chloride Mass Balance Method 
Apparent Recharge Ratea 
(mm yr1) Well 
Identifier 
Chloride 
concentration 
(mg L1) Rate 1 Rate 2 
G-2 6.5 7.8 15.7 
UZ-14 (sh) 6.7 7.4 14.8 
H-1 (Tcp) 5.7 8.9 17.9 
b#1(bh) 10.8 4.7 9.4 
c#1 7.4 6.9 13.8 
c#2 7.1 7.2 14.4 
c#3 7.2 7.1 14.2 
c#3('95) 6.5 7.8 15.7 
ONC#1 7.1 7.2 14.4 
p#1(v)b 13.0 3.9 7.8 
G-4 5.9 8.6 17.3 
H-3 9.5 5.4 10.7 
H-4 6.9 7.4 14.8 
H-5 6.1 8.4 16.7 
UZ#16 10.6 4.8 9.6 
WT#12 7.8 6.5 13.1 
WT-17 6.4 7.7 15.5 
WT#3 6.0 8.2 16.5 
DTN: GS950808312322.001, MO0007MAJIONPH.003, MO0007MAJIONPH.004, 
MO0007MAJIONPH.005, MO0007MAJIONPH.007, MO0007MAJIONPH.011, 
MO0007MAJIONPH.012, MO0007MAJIONPH.013, (chloride concentrations are listed in Table 3) 
NOTE: aRate 1 is calculated using the lower estimate for Cl concentration in precipitation (0.3 mg L1); Rate 2 is 
calculated using the higher estimate (0.6 mg L1). Recharge estimates obtained by the CMB method are 
based on Assumptions 9, 10, 12 and 13 in Table 4. 
bApproximately 28.6 percent of the water in this sample is from upward flow in the borehole from the 
carbonate aquifer (Craig and Robison 1984, p. 49).

ANL-NBS-HS-000021, REV 00 106 of 131 August 2000 
6.5.7 Evaluation of Evidence for Downgradient Dilution 
The areal distributions of chemical and isotopic constituents shown in figures in Section 6.5.1 
and the regional flow paths that were determined from these distributions (Figure 17) suggest 
that the groundwater can retain its chemical identity over transport distances of at least forty 
kilometers. Remarkably, the chemical and isotopic identity of the source water appears to be 
preserved even where regional flow paths converge as groundwater flows toward discharge areas 
south of the Site-Model boundary (Figure 17). The fact that compositional differences are 
preserved even where flow lines converge suggests that mixing and dispersion perpendicular to 
the flow lines is very limited. Therefore, dilution of chemical constituents in groundwaters that 
flow from the area of the proposed repository is also expected to be very limited. 
Locations where dilution of chemical and radiological constituents along potential flowpaths 
might be expected include the area where groundwaters from beneath the footprint of the 
proposed repository encounter the groundwaters in Fortymile Wash and the area where 
groundwaters in Fortymile Wash encounter the groundwaters of the Amargosa Desert. These 
areas will be discussed separately. 
6.5.7.1 Evaluation of Evidence for Dilution of Constituents in Yucca Mountain 
Groundwaters by Mixing with Groundwaters in Fortymile Wash 
The distribution of 234U/238U activity ratios shown in Figure 16 indicates that the high activity 
ratios found in samples from boreholes on Yucca Mountain do not occur in boreholes in 
Fortymile Wash. Because flowlines based on chloride concentrations feed into Fortymile Wash 
from the northwest, the high 234U/238U activity ratios might be expected to extend to the 
Fortymile Wash boreholes. One possible reason they do not is that mixing of groundwater from 
Yucca Mountain with groundwater from further upgradient in Fortymile Wash has decreased the 
uranium activity ratios in groundwaters in wells J-12, JF#3, and J-13. 
If this dilution process does operate as envisioned (i.e., a two-component mixing process), and if 
uranium acts as a conservative component in the Yucca Mountain and Fortymile Wash 
groundwaters, the 234U/238U activity ratio of the mixture could be derived using the following 
equation (Faure 1977, p. 98): 
234 U 
238 U 
. 
. 
. . 
. 
. 
mixture 
= 
[U]a#2[U]WT#3 
234U 
238U 
. 
. 
. 
. 
. 
. 
WT#3 
- 
234U 
238U 
. 
. 
. 
. 
. 
. 
a#2 
. 
. 
. 
. 
. 
. 
[U]mixture [U]a# 2 -[U]WT#3 ( ) + 
[U]a#2 
234U 
238U 
. 
. 
. 
. 
. 
. 
a#2 
-[U]WT#3 
234U 
238U 
. 
. 
. 
. 
. 
. 
WT#3 
[U]a# 2 -[U]WT#3 ( ) 
(Eq. 5) 
The 234U/238U activity ratio in a groundwater sample from borehole a#2 is 4.0, and the average 
uranium concentration is 0.67 (DTN: GS980108312322.003). The water in this well could be 
used as one end member in the mixing equation. Well WT#3 is the closest well with a high 
234U/238U activity ratio typical of wells on Yucca Mountain. The water from this well could be 
used as the other end member in the mixing calculation. Three samples from this well give an 
average 234U/238U activity ratio of 7.2, with a range of 7.207 to 7.283, and an average uranium

ANL-NBS-HS-000021, REV 00 107 of 131 August 2000 
concentration of 0.77 ppb, with a range of 0.756 to 0.776 (DTN: GS980908312322.009). A 
problem exists with choosing the uranium concentration to be used for the mixture. The wells 
J-12 and JF#3 could logically be considered to be downgradient of wells a#2 and WT#3 and, 
thereby, be potential candidates for representing the mixed water. However, the uranium 
concentrations measured for groundwater from the former two wells are 0.3 and 0.8 ppb, 
respectively. Both of these values are outside the range of uranium concentrations measured in 
samples of the end-member groundwaters. This fact precludes the use of the mixing equation. 
The total range of uranium concentrations in groundwaters identified as potential end members 
in the mixing problem is 0.3 to 0.8 ppb. Because this range is small, it may be appropriate to 
assume that uranium concentrations are the same in all the waters involved in the mixing process 
and use a simpler mixing equation. In the simpler equation, the proportion of each end-member 
water in the mixture is given by the following: 
X = 
234U 
238U 
. 
. 
. 
. 
. 
. 
mixture 
- 
234U 
238U 
. 
. 
. 
. 
. 
. 
WT#3 
234U 
238U 
. 
. 
. 
. 
. 
. 
a#2 
- 
234U 
238U 
. 
. 
. 
. 
. 
. 
WT#3 
(Eq. 6) 
where X is the fraction of groundwater from borehole a#2 in the mixture. In the two-component 
mixture, the fraction of groundwater from borehole WT#3 in the mixture would be 1  X. The 
234U/238U activity ratios of groundwater samples from wells JF#3 and J-12 are 4.1 and 5.5, 
respectively (DTN: GS930108315213.004). If it is assumed that the 234U/238U activity ratio for 
groundwater JF#3 represents the ratio of the mixture, the proportion of a#2 in the mixture would 
be 0.96. On the other hand, if it assumed that the 234U/238U activity ratio for groundwater J-12 
represents the ratio of the mixture, the proportion of a#2 in the mixture would be 0.5. These 
proportions indicate dilution factors of 25 and 2 (or less if the flow path from Yucca Mountain 
does not extend to Fortymile Wash), respectively, for the WT#3 component. 
Interestingly, the 234U/238U activity ratios measured in samples of J-13 water over a period of 4 
yr range from 5.4 in 1994 to 7.3 in 1997 (DTN: GS960908315215.013, GS980108312322.003). 
These data suggest groundwater in Fortymile Wash can have a range of 234U/238U activity ratios. 
However, an alternative interpretation of these data is that the large volumes of water pumped 
from this well over this time interval have drawn high 234U/238U activity-ratio groundwater from 
Yucca Mountain (e.g., WT#3) into the aquifers beneath Fortymile Wash. 
Unfortunately, the limited number of data points available for samples from Fortymile Wash 
make it difficult to more tightly constrain potential mixing/dilution processes between 
groundwaters from Yucca Mountain and Fortymile Wash using uranium concentrations and 
isotopic ratios. The data available on other conservative constituents are also inadequate to 
realistically constrain potential mixing processes.

ANL-NBS-HS-000021, REV 00 108 of 131 August 2000 
6.5.7.2 Evaluation of Evidence for Dilution of Constituents in Fortymile Wash 
Groundwaters by Mixing with Groundwaters and Local Recharge in the 
Amargosa Valley 
As shown in Figure 5, groundwaters with Cl concentrations between 6 and 7 mg L1 are present 
at the boundary of the Site-Model Area along a continuation of the Fortymile Wash trend with 
higher concentrations evident in groundwaters to the east and west. This result suggests that 
there may not be significant dilution of constituents in Fortymile Wash groundwaters as they 
enter the alluvium in the Amargosa Valley. However, the possibility exists that low Cl 
concentrations in groundwaters in the Amargosa Valley alluvial aquifer reflect local recharge as 
well as inflow from upgradient. If local recharge were a significant proportion of groundwaters 
in Amargosa Valley alluvial aquifer, this should be reflected in the stable isotope, major ion, and 
14C data for these groundwaters. These data are discussed in the following sections. 
6.5.7.2.1 Evaluation of Evidence from Deuterium and Oxygen-18 
A scattergram of the available dD and d18O data from the Amargosa Desert and from upgradient 
areas is shown in Figure 26. Many of the data plot below the present-day global meteoric water 
line (dD = 8 d18O + 10) or the Yucca Mountain meteoric water line determined from snow 
samples (dD = 8 d18O + 8.9) (Benson and Klieforth 1989, Fig. 14). The most enriched (i.e., least 
negative) samples are those from Fortymile Wash; the lightest samples are those from Skeleton 
Hills and Crater Flat. 
The dD and d18O data help to distinguish the source of the groundwater associated with 
Fortymile Wash in the Amargosa Desert. The dD values of groundwater near Fortymile Wash in 
the Amargosa Desert (FMW-S samples in Figure 26) are lower than the dD values of 
groundwater near Fortymile Wash east of Yucca Mountain (FMW-N samples), suggesting either 
a different origin or a different age for the groundwater in these two areas. The more depleted 
dD values associated with Fortymile Wash in the Amargosa Desert may be reflecting a 
predominantly Pleistocene age of groundwater in the Amargosa Desert. The observation that 
most of the low chloride groundwater samples from the Amargosa Desert (FMW-S, FMW-W, 
FMW-E, and SH samples in Figure 26) appear to be associated with a meteoric water line with a 
smaller deuterium excess (dD = 8 d18O + 5) than the present-day global or local Yucca Mountain 
meteoric water lines also may be indicating a predominantly Pleistocene origin for Amargosa 
Desert groundwater. The value of the deuterium excess decreases with increasing relative 
humidity in the moisture source area, and relative humidity would be expected to have been 
higher over the oceans in the Pleistocene, when global temperatures were cooler than at present 
(Section 6.5.4.1; Clark and Fritz 1997, p. 45; Merlivat and Jouzel 1979, p. 5029). 
Data for two samples indicate that groundwater near the Skeleton Hills and Gravity Fault is more 
depleted in dD and d18O than is groundwater near Fortymile Wash. The difference in the dD and 
d18O compositions of groundwater from the Fortymile Wash area in the Amargosa Desert and 
groundwater near the Skeleton Hills and Gravity Fault areas supports the contention that these 
groundwaters have different source areas and that groundwater near the Skeleton Hills and 
Gravity Fault is not simply groundwater from Fortymile Wash that has been chemically modified 
by interaction with carbonate alluvium near the Skeleton Hills. Unlike major cations and anions, 
the dD and d18O compositions would not be substantially modified by water/rock interaction

ANL-NBS-HS-000021, REV 00 109 of 131 August 2000 
with the carbonate alluvium. The dD and d18O compositions of groundwater near the Skeleton 
Hills and Gravity Fault is similar to water from the carbonate aquifer at Yucca Mountain 
(p#1(c)) and from Fairbanks Spring, the northernmost large spring in Ash Meadows (Figure 26). 
This observation is consistent with the interpretation that the groundwater in the alluvium near 
the Skeleton Hills and Gravity Fault is derived from upward leakage from the carbonate aquifer 
along the fault (Winograd and Thordarson 1975, pp. C84C85, C112). 
DTN: GS000700012847.001, GS950808312322.001, GS970708312323.001, MO0007GNDWTRIS.002, MO0007GNDWTRIS.003, 
MO0007GNDWTRIS.005, MO0007GNDWTRIS.006, MO0007GNDWTRIS.007, MO0007GNDWTRIS.008, 
MO0007GNDWTRIS.009, MO0007GNDWTRIS.010, MO0007GNDWTRIS.011, MO0007GNDWTRIS.012, 
USGS (n.d.) (see Assumption 23 in Table 4) 
NOTE: This figure has color-coded data points and should not be read in a black and white version. 
Figure 26. Delta Deuterium Versus Delta Oxygen-18 of Groundwater 
in the Amargosa Desert and in Upgradient Areas 
6.5.7.2.2 Evaluation of Evidence from 14C Data 
Generally, groundwater in Amargosa Valley alluvium near the Fortymile Wash drainage has 14C 
activities that range between 10 and 28 pmc (Figure 15). Groundwater near the Skeleton Hills 
(SH) and Gravity Fault (GF) has 14C activities that are about 10 pmc or less. 
The variable 14C activities of groundwater near Fortymile Wash in the Amargosa Desert were 
attributed by Claassen (1985, p. F27) to variable distances from surface drainageways, rather

ANL-NBS-HS-000021, REV 00 110 of 131 August 2000 
than to variable well depths. In the Amargosa Desert, 14C activities near Fortymile Wash do not 
show any obvious trend that would indicate that groundwater in the lower reaches of the Wash is 
older than groundwater beneath its upper reaches, a trend that would be expected if groundwater 
beneath the lower reaches was derived primarily by southerly groundwater flow beneath the 
Wash. 
Three lines of evidence support the contention that groundwater near the Fortymile Wash in the 
Amargosa Desert was recharged no later than the early Holocene. First, the uncorrected 14C ages 
for groundwater samples with 14C activities less than 30 pmc are greater than about 10,000 yr 
(Table 8), which is consistent with late Pleistocene recharge as the source for the groundwater in 
the Amargosa Desert. An initial 14C activity (14A0) of about 65 pmc was determined by 
groundwater samples from borehole a#2, which had bomb-pulse concentrations of tritium and 
36Cl but a 14C activity of approximately 62 pmc. Assuming that groundwater in the Amargosa 
Desert near Fortymile Wash was recharged by water having an initial 14C activity of 65 pmc, the 
age of Amargosa Desert groundwater near Fortymile Wash is between 7,000 and 15,500 yr. The 
lower limits of this age range are about 2,000 yr less than the bounding ages for the Fortymile 
Wash groundwater presented in Claassen (1985, Fig. 15). 
A second line of evidence is the association of the dD and d18O values of Amargosa groundwater 
with a paleometeoric water line consistent with a paleoclimate more humid and cooler than the 
prevailing climate. A related line of evidence is that, for groundwater in the Yucca Mountain 
area and Amargosa Desert, dD is roughly correlated with 14C activity (Figure 27). The 
correlation trend supports the hypothesis that groundwater depleted in dD contains a greater 
fraction of water recharged during the Pleistocene when temperatures were relatively cool than 
does groundwater enriched in dD. 
Finally, the uncorrected ages for the groundwater near Fortymile Wash in the Amargosa Desert 
are consistent with data from radiocarbon-dated plant assemblages preserved in packrat middens 
in the Skeleton Hills. These data indicate that wetter conditions in the Amargosa Desert 
persisted until about 9,300 yr before present, at which time conditions abruptly became more arid 
(Spaulding and Graumlich 1986, Fig. 3a). The absence of groundwater samples with 
uncorrected 14C ages less than 9,000 yr supports the contention that recharge has not been 
important in the Amargosa Desert near Fortymile Wash during the Holocene (Claassen 1985, 
Fig. 14, p. F27).

ANL-NBS-HS-000021, REV 00 111 of 131 August 2000 
DTN: GS930908312323.003, GS950808312322.001, MO0007GNDWTRIS.002, MO0007GNDWTRIS.003, 
MO0007GNDWTRIS.005, MO0007GNDWTRIS.006, MO0007GNDWTRIS.007, MO0007GNDWTRIS.008, 
MO0007GNDWTRIS.009, MO0007GNDWTRIS.010, MO0007GNDWTRIS.012, USGS (n.d.) (see Assumption 23 in Table 4) 
NOTE: This figure has color-coded data points and should not be read in a black and white version. 
Figure 27. Delta Deuterium Versus Carbon-14 Activity of Groundwater 
in the Amargosa Desert and in Upgradient Areas

ANL-NBS-HS-000021, REV 00 112 of 131 August 2000 
INTENTIONALLY LEFT BLANK

ANL-NBS-HS-000021, REV 00 113 of 131 August 2000 
7. SUMMARY AND CONCLUSIONS 
Hydrochemical data from the saturated zone in the Yucca Mountain region were compiled, 
documented, and analyzed in this report. The data were collected over several decades by 
different organizations, sometimes under less than optimal sampling conditions. Moreover, data 
are sparse or lacking altogether at critical locations. As a result, the data are subject to multiple 
interpretations. The following summary includes the favored interpretations, based on the data 
and analysis in this report. It should be recognized that the acquisition of new data could change 
the interpretations presented in this report or suggest new interpretations not previously 
considered. Additionally, various hypotheses suggested by the hydrochemical and isotopic data 
have yet to be systematically investigated with numerical flow and transport models of the site. 
A systematic analysis of the hypotheses discussed in this report combined with improved models 
of the site hydrologic system could change the present understanding of the flow system. 
7.1 REGIONAL FLOW PATHS 
Areal distributions of chemical and isotopic data were used to constrain flow paths in the region. 
The analysis traces flow paths by connecting upgradient areas with distinct chemical 
compositions to downgradient areas with similar chemical compositions. The map of the 
potentiometric surface was used to guide, but not determine, the selection of which downgradient 
areas could potentially be linked by a flow path to an upgradient area. Because the flow-path 
analysis presented assumes that groundwater can be traced in two dimensions, it does not 
consider the possible effects of local recharge and vertical mixing between aquifers. 
Flow paths can be traced using chemistry and isotopes only where compositional differences 
exist that allow some directions to be eliminated as possible flow directions. Because no single 
chemical or isotopic species varies sufficiently to determine flow paths everywhere in the study 
area, multiple chemical and isotopic species were used to construct the flow paths. The flowpath 
analysis assumed that the dD, d18O, Cl, SO4
2, Na+, and Ca2+ composition of groundwater 
along a flow path did not change because of water/rock interaction, recharge of water with a 
different composition, or vertical mixing between aquifers. 
Flow Path 1 shows groundwater moving roughly parallel to the Amargosa River from an area 
west of Bare Mountain toward the southwest corner of the Site-Model Area (Figure 17). Flow 
Path 2 indicates that groundwater flows parallel to Fortymile Wash to connect upgradient areas 
in Fortymile Canyon with downgradient areas in the Amargosa Desert. Groundwater following 
Flow Path 3 flows from areas in the northwest corner of the Site Model, through central Crater 
Flat, and then southward to the southern boundary of the Site Model. Groundwater in central 
Jackass Flats flows southwestward along Flow Path 4, roughly parallel to Fortymile Wash in the 
vicinity of Amargosa Valley, before turning south-southeast near the southern boundary of the 
Site-Model Area. Flow Path 5 shows groundwater moving predominantly south-southeast in 
eastern Crater Flat and then south-southwest after reaching the southern edge of Yucca 
Mountain. Groundwater from beneath the potential repository area is estimated to flow southeast 
along Dune Wash (Flow Path 6) toward Fortymile Wash and then south/southwest, or roughly 
parallel to Fortymile Wash, toward the Amargosa Desert.

ANL-NBS-HS-000021, REV 00 114 of 131 August 2000 
The regional flow paths constructed on the basis of the hydrochemical and isotopic data are 
generally consistent with flow paths that could be inferred from the potentiometric surface but 
with a stronger north-south component. The stronger north-south component could be reflecting 
the general north-south structural fabric of the rock, the inability of the method to account for 
chemical mixing due to recharge or upwelling from the carbonate aquifer, or simply the 
sparseness of the data in certain regions of the model area. 
7.2 EVALUATION OF EVIDENCE FOR LOCAL RECHARGE 
Hydrochemical and isotopic data from perched water at Yucca Mountain were compared to 
similar data from the regional groundwater system at Yucca Mountain to verify whether local 
recharge is present in the groundwater. The data examined included uranium isotopes 
(234U/238U) and major anions and cations. Based on this comparison, local recharge, as 
represented by the perched water, was inferred to be a major component in the groundwater 
beneath Yucca Mountain. Realistic quantification of the percentage of local recharge in 
groundwater beneath Yucca Mountain is not possible with the currently available hydrochemical 
database. The conservative position on this issue would be to assume shallow groundwater is 
composed entirely of local recharge. 
7.3 EVALUATION OF EVIDENCE FOR TIMING OF RECHARGE 
The timing of recharge at Yucca Mountain as determined by the uncorrected 14C ages of the 
perched water is predominantly between 11,000 and 7,000 yr before present. However, the 
possibility exists that even younger recharge may be present in the groundwater beneath Yucca 
Mountain because of the presence of some perched water with a younger 14C age and the absence 
of shallow groundwater samples from fault zones and other likely paths for rapid recharge. 
Corrections to the 14C ages of groundwater in the vicinity of Yucca Mountain were made using 
the geochemical code NETPATH, which considers the plausible chemical reactions that may 
have produced the observed chemistry of the groundwater samples. The corrected 14C ages of 
the groundwater were approximately one 14C half-life (5715 yr) younger than the uncorrected 
14C ages, which were about 22,000 to 18,000 yr in Crater Flat, 14,000 to 12,000 yr in northern 
Yucca Mountain, 18,000 to 15,000 yr in southern Yucca Mountain, and 13,000 to 9,000 yr 
beneath Fortymile Wash. Because of the assumption that all the carbon contributed by carbonate 
dissolution had a 14C activity of 0 pmc and because the model did not consider the increase in 
Ca2+ and Mg2+ in soil water due to evaporation in the soil zone, the corrected 14C ages are 
considered lower limits for the true average age. The true 14C ages probably are bounded by the 
corrected and uncorrected 14C ages. 
The 14C activity of recently recharged groundwater near Fortymile Wash was used to support an 
estimate for the initial 14C activity of recharge (14A0) of approximately 65 pmc for this setting. 
This value of 14A0 for the Fortymile Wash area is less than the value of 100 pmc previously 
assumed for that area by Benson and Klieforth (1989, p. 42), which had been based on the 14C 
activity of calcite-saturated surface runoff in the wash. It is not possible to conclusively 
reconcile the difference in these two values for 14A0. Estimated groundwater 14C ages calculated

ANL-NBS-HS-000021, REV 00 115 of 131 August 2000 
with a 14A0 value of 65 pmc are approximately 3700 yr younger than the uncorrected ages and 
are considered to be the best estimate of groundwater 14C ages in the Yucca Mountain area. 
7.4 EVALUATION OF EVIDENCE FOR MIXING RELATIONS BETWEEN 
DIFFERENT WATERS AT YUCCA MOUNTAIN 
An evaluation of potential mixing relations among waters in the Yucca Mountain region is 
important because such mixing could lead to dilution of constituents that might be released to 
groundwater beneath the potential repository. Unfortunately, proving the occurrence of mixing 
between two or more groundwaters is a difficult problem. In fact, the available hydrochemical 
database is inadequate to prove the existence of mixing processes between groundwaters in the 
Yucca Mountain region beyond a reasonable doubt. To the contrary, the available 
hydrochemical database can be used to argue that there is minimal mixing between groundwater 
in the carbonate and volcanic aquifers beneath Yucca Mountain. 
7.5 EVALUATION OF EVIDENCE FOR THE MAGNITUDE OF RECHARGE 
Estimates of the magnitude of recharge at Yucca Mountain were obtained using the chloride 
mass balance (CMB) method. This method is simple and appears reliable based on comparisons 
with other techniques used to estimate the magnitude of recharge. The estimates range from less 
than 0.5 mm yr1 beneath washes with thick alluvial cover to a maximum of 20 mm yr1 beneath 
ridge tops and side slopes. For groundwaters within the immediate vicinity of Yucca Mountain, 
chloride concentrations range from 5 to 9 mg L1, indicating local recharge rates between 7 and 
14 mm yr1. 
7.6 EVALUATION OF EVIDENCE FOR DOWNGRADIENT DILUTION 
If groundwater from Yucca Mountain flows toward Fortymile Wash, as suggested by the flow 
lines drawn on the basis of potentiometric and hydrochemical data, the potential exists for 
constituents in Yucca Mountain groundwater to be diluted by groundwaters below Fortymile 
Wash. Uranium concentration and isotope data were used to evaluate this potential dilution 
process. It was assumed that the uranium concentrations and activity ratios are conservative 
parameters in the flow systems involved. 
The potential for mixing was evaluated using a two-component mixing equation involving the 
uranium concentration and 234U/238U activity ratio. Uranium concentration and isotopic data are 
available only for five wells in the area of interest, and these data do not allow a unique solution 
to this mixing equation. In effect, the range in uranium concentrations measured for multiple 
samples of the mixing end-member groundwaters is similar to the total range of uranium 
concentrations observed for the full set of groundwater analyses. If it is assumed that the 
uranium concentrations in the end-member groundwaters are the same in the mixing process, 
then the mixing proportions are only a function of the differences in the uranium activity ratios. 
Under this assumption, the estimated proportions of the Fortymile Wash component in the 
mixture range from 0.5 to 0.9 depending on which downgradient groundwater (from borehole 
J-12 or JF#3) is used to represent the mixed water.

ANL-NBS-HS-000021, REV 00 116 of 131 August 2000 
The areal plot of chloride concentrations in groundwaters within the model boundary suggests 
that low chloride concentrations typical of groundwaters beneath Yucca Mountain and Fortymile 
Wash extend to wells at the southern boundary of the model area. This observation, in turn, 
suggests there would be minimal dilution of constituents that may be present in upgradient 
groundwaters by mixing with groundwaters within alluvium of the Amargosa Valley. 
An alternative interpretation is that the low chloride concentrations found in some Amargosa 
Valley wells reflect local recharge. In this case, dilution of constituents in upgradient waters by 
mixing with groundwaters in Amargosa Valley alluvium is a viable process. However, the 
viability of this interpretation is brought into question by data that suggest the groundwaters in 
Amargosa Valley alluvium are as old or older than groundwaters at Yucca Mountain. If these 
groundwaters had a large component of local recharge, they would be expected to have relatively 
young ages. On the other hand, the available age data would be consistent with the idea that 
these waters are largely composed of flow from upgradient sources north of Amargosa Desert 
(i.e., from Fortymile Wash) or with paleorecharge along Fortymile Wash in the Amargosa Desert 
itself. 
7.7 RECOMMENDATIONS 
The analyses presented in this report have highlighted the need for particular types of data in 
certain areas. A sampling strategy that would reduce uncertainty in key elements of the 
conceptual model of groundwater flow in the Yucca Mountain area is outlined in this section. 
7.7.1 Upgradient Sampling Locations 
Groundwater beneath Yucca Mountain seems to be composed of water from several sources. 
Local recharge and groundwater flow from the north or west remain likely possibilities. Local 
recharge (as represented by perched water) and shallow groundwater in the north, as represented 
by samples from borehole G-2, are dilute with respect to Cl and SO4
2, have high 
(Ca2+ + Mg2+)/(Na+ + K+) ratios and low Na+ concentrations, and are enriched in dD, d18., and 
14C compared to most groundwater samples from Yucca Mountain. A second source of 
groundwater, more concentrated in Cl and SO4
2, with lower (Ca2+ + Mg2+)/(Na+ + K+) ratios 
and higher Na+ concentrations and with greater depletion of dD, d18. and 14C compared to the 
first source, is also present at Yucca Mountain. Groundwater in Crater Flat has many of the 
characteristics of the second source. The sample from borehole G-2, the sole groundwater 
sample in northernmost Yucca Mountain, originated from the relatively shallow Calico Hills 
Formation. Deep groundwater, from the Prow Pass and Bullfrog Tuffs, has not been sampled in 
northern Yucca Mountain, and its chemical and isotopic characteristics are unknown. We 
propose that borehole WT-6 in Yucca Wash be extended from its present depth in the Calico 
Hills Formation through the Bullfrog Tuff to evaluate the chemical and isotopic characteristics of 
deep groundwater in northernmost Yucca Mountain. 
7.7.2 Local Recharge Sampling 
Most existing groundwater samples were obtained by pumping boreholes from intervals that 
were open to flow over a large range of depths. Frequently, flow logs taken during pumping

ANL-NBS-HS-000021, REV 00 117 of 131 August 2000 
indicated that inflow to the boreholes was over widely separated, discrete intervals. Despite 
possible groundwater mixing during sampling, the existing samples suggest that local recharge 
may be present in groundwater beneath Yucca Mountain. To further examine this hypothesis, 
and to better determine the extent and character of local recharge at Yucca Mountain, it is 
proposed that shallow groundwater be sampled from the vicinity of faults, where focussed 
recharge may be present. Borehole WT-2 is a strong candidate for sampling because of its 
location within the potential repository area and because it intersects the water table near the 
Ghost Dance Fault. Borehole WT-1 is also a strong candidate for sampling because of its 
proximity to the Dune Wash Fault and its location downgradient from the potential repository 
area. Both of these boreholes are open to the saturated zone only within a few tens of meters of 
the water table and local recharge, if present, would have a good chance of being detected. 
7.7.3 Discrete Interval Sampling 
One conceptual model of flow of groundwater at Yucca Mountain is that local recharge pushes 
underflow from areas upgradient of Yucca Mountain deeper into the flow system. In this model, 
both local and upgradient sources of recharge remain in their respective flow tubes and do not 
undergo much mixing. Mixing that seems to be evident in trends exhibited by the groundwater 
samples is, in this model, mostly or entirely attributed to mixing in the borehole during pumping. 
Chemical and isotopic trends, or the lack thereof, are attributed by this model to the effects of 
sampling variable amounts of groundwater from flow tubes containing groundwater from 
different sources. It is proposed that groundwater samples be collected in existing and planned 
deep boreholes, such as those drilled as part of the NC-EWDP, in such a way as to maximize the 
chances of detecting compositional differences between groundwater in shallow and deep zones. 
7.7.4 Fault Plane Sampling 
Groundwater sampled from near faults in southern Yucca Mountain at the NC-EWDP boreholes 
and CIND-R-LITE Well is similar in composition to groundwater in Crater Flat, an observation 
that suggests groundwater from the potential repository area is not moving southwestward under 
the fault-block ridges in southernmost Yucca Mountain. Groundwater samples from existing and 
planned boreholes located along these faults would provide valuable additional evidence to 
evaluate this hypothesis. Of existing wells, borehole WT-11 is favorably situated to help in this 
evaluation and groundwater samples from this borehole would also be useful in narrowing 
existing gaps in areal coverage. Some future boreholes should be located so as to directly 
sample groundwater from faults in southern Yucca Mountain. 
* * * 
This document and its conclusions may be affected by technical product input information that 
requires confirmation. Any changes to the document or its conclusions that may occur as a result 
of completing the confirmation activities will be reflected in subsequent revisions. The status of 
the input information quality may be confirmed by review of the document input reference 
system database.

ANL-NBS-HS-000021, REV 00 118 of 131 August 2000 
INTENTIONALLY LEFT BLANK

ANL-NBS-HS-000021, REV 00 119 of 131 August 2000 
8. REFERENCES 
8.1 CITED REFERENCES 
Benson, L. and Klieforth, H. 1989. "Stable Isotopes in Precipitation and Ground Water in the 
Yucca Mountain Region, Southern Nevada: Paleoclimatic Implications." Geophysical 
Monograph, 55, 41-59. Washington, D.C.: American Geophysical Union. TIC: 224413. 
Benson, L.V. and McKinley, P.W. 1985. Chemical Composition of Ground Water in the Yucca 
Mountain Area, Nevada, 1971-84. Open-File Report 85-484. Denver, Colorado: U.S. Geological 
Survey. ACC: NNA.19900207.0281. 
Benson, L.V.; Robison, J.H.; Blankennagel, R.K.; and Ogard, A.E. 1983. Chemical Composition 
of Ground Water and the Locations of Permeable Zones in the Yucca Mountain Area, Nevada. 
Open-File Report 83-854. Denver, Colorado: U.S. Geological Survey. ACC: 
NNA.19870610.0028. 
Bish, D.L. 1989. Evaluation of Past and Future Alterations in Tuff at Yucca Mountain, Nevada, 
Based on the Clay Mineralogy of Drill Cores USW G-1, G-2, and G-3. LA-10667-MS. Los 
Alamos, New Mexico: Los Alamos National Laboratory. ACC: NNA.19890126.0207. 
Bish, D.L. and Chipera, S.J. 1989. Revised Mineralogic Summary of Yucca Mountain, Nevada. 
LA-11497-MS. Los Alamos, New Mexico: Los Alamos National Laboratory. ACC: 
NNA.19891019.0029. 
Broxton, D.E.; Bish, D.L.; and Warren, R.G. 1987. "Distribution and Chemistry of Diagenetic 
Minerals at Yucca Mountain, Nye County, Nevada." Clays and Clay Minerals, 35, (2), 89-110. 
Long Island City, New York: Pergamon Press. TIC: 203900. 
Buesch, D.C.; Spengler, R.W.; Moyer, T.C.; and Geslin, J.K. 1996. Proposed Stratigraphic 
Nomenclature and Macroscopic Identification of Lithostratigraphic Units of the Paintbrush 
Group Exposed at Yucca Mountain, Nevada. Open-File Report 94-469. Denver, Colorado: U.S. 
Geological Survey. ACC: MOL.19970205.0061. 
Campana, M.E. and Byer, R.M., Jr. 1996. "A Conceptual Evaluation of Regional Ground-Water 
Flow, Southern Nevada-California, USA." Environmental and Engineering Geoscience, II, (4), 
465-478. Boulder, Colorado: Geological Society of America. TIC: 246651. 
Carr, W.J.; Byers, F.M., Jr.; and Orkild, P.P. 1986. Stratigraphic and Volcano-Tectonic 
Relations of Crater Flat Tuff and Some Older Volcanic Units, Nye County, Nevada. Professional 
Paper 1323. Denver, Colorado: U.S. Geological Survey. TIC: 216598. 
Claassen, H.C. 1985. Sources and Mechanisms of Recharge for Ground Water in the West- 
Central Amargosa Desert, Nevada  A Geochemical Interpretation. Professional Paper 712-F. 
Washington, D.C.: U.S. Geological Survey. TIC: 204574.

ANL-NBS-HS-000021, REV 00 120 of 131 August 2000 
Clark, I.D. and Fritz, P. 1997. Environmental Isotopes in Hydrogeology. Boca Raton, Florida: 
Lewis Publishers. TIC: 233503. 
Craig, R.W. and Robison, J.H. 1984. Geohydrology of Rocks Penetrated by Test Well UE-25p#1, 
Yucca Mountain Area, Nye County, Nevada. Water-Resources Investigations Report 84-4248. 
Denver, Colorado: U.S. Geological Survey. ACC: NNA.19890905.0209. 
CRWMS M&O 1999a. Geochemical and Isotopic Constraints on Groundwater Flow Directions, 
Mixing and Recharge at Yucca Mountain, Nevada. TDP-NBS-HS-000019 REV 00. Las Vegas, 
Nevada: CRWMS M&O. ACC: MOL.19990819.0005. 
CRWMS M&O 1999b. M&O Site Investigations. Activity Evaluation, January 23, 1999. Las 
Vegas, Nevada: CRWMS M&O. ACC: MOL.19990317.0330. 
CRWMS M&O 1999c. M&O Site Investigations -- (Q). Activity Evaluation, September 28, 
1999. Las Vegas, Nevada: CRWMS M&O. ACC: MOL.19990928.0224. 
CRWMS M&O 2000. Analysis of Geochemical Data for the Unsaturated Zone. ANL-NBS-HS- 
000017 REV 00. Las Vegas, Nevada: CRWMS M&O. ACC: MOL.20000725.0453. 
Czarnecki, J.B. 1984. Simulated Effects of Increased Recharge on the Ground-Water Flow 
System of Yucca Mountain and Vicinity, Nevada-California. Water-Resources Investigations 
Report 84-4344. Denver, Colorado: U.S. Geological Survey. ACC: HQS.19880517.1750. 
Czarnecki, J.B. and Waddell, R.K. 1984. Finite-Element Simulation of Ground-Water Flow in 
the Vicinity of Yucca Mountain, Nevada-California. Water-Resources Investigations Report 84- 
4349. Denver, Colorado: U.S. Geological Survey. ACC: NNA.19870407.0173. 
Czarnecki, J.B.; Faunt, C.C.; Gable, C.W.; and Zyvoloski, G.A. 1997. Hydrogeology and 
Preliminary Calibration of a Preliminary Three-Dimensional Finite-Element Ground-Water 
Flow Model of the Site Saturated Zone, Yucca Mountain, Nevada. Administrative Report. 
Denver, Colorado: U.S. Geological Survey. ACC: MOL.19980204.0519. 
D'Agnese, F.A.; Faunt, C.C.; Turner, A.K.; and Hill, M.C. 1997. Hydrogeologic Evaluation and 
Numerical Simulation of the Death Valley Regional Ground-Water Flow System, Nevada and 
California. Water-Resources Investigations Report 96-4300. Denver, Colorado: U.S. Geological 
Survey. ACC: MOL.19980306.0253. 
Day, W.C.; Potter, C.J.; Sweetkind, D.S.; Dickerson, R.P.; and San Juan, C.A. 1998. Bedrock 
Geologic Map of the Central Block Area, Yucca Mountain, Nye County, Nevada. Map I-2601. 
Washington, D.C.: U.S. Geological Survey. TIC: 237019. 
Dettinger, M.D. 1989. "Reconnaissance Estimates of Natural Recharge to Desert Basins in 
Nevada, U.S.A., by Using Chloride-Balance Calculations." Journal of Hydrology, 106, 55-78. 
Amsterdam, The Netherlands: Elsevier Science. TIC: 236967.

ANL-NBS-HS-000021, REV 00 121 of 131 August 2000 
DOE (U.S. Department of Energy) 2000. Quality Assurance Requirements and Description. 
DOE/RW-0333P, Rev. 9. Washington, D.C.: U.S. Department of Energy, Office of Civilian 
Radioactive Waste Management. ACC: MOL.19991028.0012. 
Dyer, J.R. 1999. "Revised Interim Guidance Pending Issuance of New U.S. Nuclear Regulatory 
Commission (NRC) Regulations (Revision 01, July 22, 1999), for Yucca Mountain, Nevada." 
Letter from J.R. Dyer (DOE/YMSCO) to D.R. Wilkins (CRWMS M&O), September 3, 1999, 
OL&RC:SB-1714, with enclosure, "Interim Guidance Pending Issuance of New NRC 
Regulations for Yucca Mountain (Revision 01)." ACC: MOL.19990910.0079. 
Faure, G. 1977. Principles of Isotope Geology. New York, New York: John Wiley & Sons. TIC: 
235628. 
Forester, R.M.; Bradbury, J.P.; Carter, C.; Elvidge-Tuma, A.B.; Hemphill, M.L.; Lundstrom, 
S.C.; Mahan, S.A.; Marshall, B.D.; Neymark, L.A.; Paces, J.B.; Sharpe, S.E.; Whelan, J.F.; and 
Wigand, P.E. 1999. The Climatic and Hydrologic History of Southern Nevada During the Late 
Quaternary. Open-File Report 98-635. Denver, Colorado: U.S. Geological Survey. TIC: 245717. 
Fridrich, C.J.; Dudley, W.W., Jr.; and Stuckless, J.S. 1994. "Hydrogeologic Analysis of the 
Saturated-Zone Ground-Water System, Under Yucca Mountain, Nevada." Journal of Hydrology, 
154, 133-168. Amsterdam, The Netherlands: Elsevier Science B.V. TIC: 224606. 
Gascoyne, M. 1992. "Geochemistry of the Actinides and Their Daughters." Chapter 2 of 
Uranium-Series Disequilibrium: Applications to Earth, Marine, and Environmental Sciences. 
Ivanovich, M. and Harmon, R.S., eds. Pages 34-61. Oxford, England: Clarendon Press. TIC: 
246658. 
Hevesi, J.A.; Flint, A.L.; and Istok, J.D. 1992. "Precipitation Estimation in Mountainous Terrain 
Using Multivariate Geostatistics. Part II: Isohyetal Maps." Journal of Applied Meteorology, 31, 
(7), 677-688. Boston, Massachusetts: American Meteorological Society. TIC: 225248. 
Ingraham, N.L.; Lyles, B.F.; Jacobson, R.L.; and Hess, J.W. 1991. "Stable Isotopic Study of 
Precipitation and Spring Discharge in Southern Nevada." Journal of Hydrology, 125, 243-258. 
Amsterdam, The Netherlands: Elsevier Science Publishers B.V. TIC: 238581. 
Kilroy, K.C. 1991. Ground-Water Conditions in Amargosa Desert, Nevada-California, 1952-87. 
Water-Resources Investigations Report 89-4101. Carson City, Nevada: U.S. Geological Survey. 
TIC: 209975. 
Laczniak, R.J.; Cole, J.C.; Sawyer, D.A.; and Trudeau, D.A. 1996. Summary of Hydrogeologic 
Controls on Ground-Water Flow at the Nevada Test Site, Nye County, Nevada. Water-Resources 
Investigations 96-4109. Carson City, Nevada: U.S. Geological Survey. TIC: 226157. 
Langmuir, D. 1997. Aqueous Environmental Geochemistry. Upper Saddle River, New Jersey: 
Prentice Hall. TIC: 237107.

ANL-NBS-HS-000021, REV 00 122 of 131 August 2000 
Lichty, R.W. and McKinley, P.W. 1995. Estimates of Ground-Water Recharge Rates for Two 
Small Basins in Central Nevada. Water-Resources Investigations Report 94-4104. Denver, 
Colorado: U.S. Geological Survey. ACC: MOL.19960924.0524. 
Luckey, R.R.; Tucci, P.; Faunt, C.C.; Ervin, E.M.; Steinkampf, W.C.; D'Agnese, F.A.; and 
Patterson, G.L. 1996. Status of Understanding of the Saturated-Zone Ground-Water Flow System 
at Yucca Mountain, Nevada, as of 1995. Water-Resources Investigations Report 96-4077. 
Denver, Colorado: U.S. Geological Survey. ACC: MOL.19970513.0209. 
McKinley, P.W.; Long, M.P.; and Benson, L.V. 1991. Chemical Analyses of Water from 
Selected Wells and Springs in the Yucca Mountain Area, Nevada and Southeastern California. 
Open-File Report 90-355. Denver, Colorado: U.S. Geological Survey. ACC: 
NNA.19901031.0004. 
Merlivat, L. and Jouzel, J. 1979. "Global Climatic Interpretation of the Deuterium-Oxygen 18 
Relationship for Precipitation." Journal of Geophysical Research, 84, (C8), 5029-5033. 
Washington, D.C.: American Geophysical Union. TIC: 247773. 
Milne, W.K.; Benson, L.V.; and McKinley, P.W. 1987. Isotope Content and Temperature of 
Precipitation in Southern Nevada, August 1983-August 1986. Open-File Report 87-463. Denver, 
Colorado: U.S. Geological Survey. ACC: NNA.19900601.0002. 
O'Brien, G.M. 1998. Analysis of Aquifer Tests Conducted in Borehole USW G-2, 1996, Yucca 
Mountain, Nevada. Water-Resources Investigations Report 98-4063. Denver, Colorado: U.S. 
Geological Survey. ACC: MOL.19980904.0095. 
Ogard, A.E. and Kerrisk, J.F. 1984. Groundwater Chemistry Along Flow Paths Between a 
Proposed Repository Site and the Accessible Environment. LA-10188-MS. Los Alamos, New 
Mexico: Los Alamos National Laboratory. ACC: HQS.19880517.2031. 
Oliver, T. and Root, T. 1997. Hydrochemical Database for the Yucca Mountain Area, Nye 
County, Nevada. Denver, Colorado: U.S. Geological Survey. ACC: MOL.19980302.0367. 
Osmond, J.K. and Cowart, J.B. 1992. "Ground Water." Chapter 9 of Uranium-Series 
Disequilibrium: Applications to Earth, Marine, and Environmental Sciences. Invanovich, M. and 
Harmon, R.S., eds. 2nd Edition. New York, New York: Oxford University Press. TIC: 234680. 
Patterson, G.L.; Peterman, Z.E.; and Paces, J.B. 1998. "Hydrochemical Evidence for the 
Existence of Perched Water at USW WT-24, Yucca Mountain, Nevada." High-Level Radioactive 
Waste Management, Proceedings of the Eighth International Conference, Las Vegas, Nevada, 
May 11-14, 1998. Pages 277-278. La Grange Park, Illinois: American Nuclear Society. TIC: 
237082. 
Perfect, D.L.; Faunt, C.C.; Steinkampf, W.C.; and Turner, A.K. 1995. Hydrochemical Data Base 
for the Death Valley Region, California and Nevada. Open-File Report 94-305. Denver, 
Colorado: U.S. Geological Survey. ACC: MOL.19940718.0001.

ANL-NBS-HS-000021, REV 00 123 of 131 August 2000 
Plummer, L.N.; Prestemon, E.C.; and Parkhurst, D.L. 1994. An Interactive Code (NETPATH) for 
Modeling Net Geochemical Reactions Along a Flow Path, Version 2.0. Water-Resources 
Investigations Report 94-4169. Reston, Virginia: U.S. Geological Survey. TIC: 234831. 
Plummer, M.A.; Phillips, F.M.; Fabryka-Martin, J.; Turin, H.J.; Wigand, P.E.; and Sharma, P. 
1997. "Chlorine-36 in Fossil Rat Urine: An Archive of Cosmogenic Nuclide Deposition During 
the Past 40,000 Years." Science, 277, 538-541. Washington, D.C.: American Association for the 
Advancement of Science. TIC: 237425. 
Quade, J. and Cerling, T.E. 1990. "Stable Isotopic Evidence for a Pedogenic Origin of 
Carbonates in Trench 14 Near Yucca Mountain, Nevada." Science, 250, 1549-1552. Washington, 
D.C.: American Association for the Advancement of Science. TIC: 222617. 
Savard, C.S. 1994. "Ground-Water Recharge in Fortymile Wash Near Yucca Mountain, Nevada, 
1992-93." High Level Radioactive Waste Management, Proceedings of the Fifth Annual 
International Conference, Las Vegas, Nevada, May 22-26, 1994. 4, 1805-1813. La Grange Park, 
Illinois: American Nuclear Society. TIC: 210984. 
Savard, C.S. 1998. Estimated Ground-Water Recharge from Streamflow in Fortymile Wash Near 
Yucca Mountain, Nevada. Water-Resources Investigations Report 97-4273. Denver, Colorado: 
U.S. Geological Survey. TIC: 236848. 
Sawyer, D.A.; Fleck, R.J.; Lanphere, M.A.; Warren, R.G.; Broxton, D.E.; and Hudson, M.R. 
1994. "Episodic Caldera Volcanism in the Miocene Southwestern Nevada Volcanic Field: 
Revised Stratigraphic Framework, 40Ar/39Ar Geochronology, and Implications for Magmatism 
and Extension." Geological Society of America Bulletin, 106, (10), 1304-1318. Boulder, 
Colorado: Geological Society of America. TIC: 222523. 
Spaulding, W.G. and Graumlich, L.J. 1986. "The Last Pluvial Climatic Episodes in the Deserts 
of Southwestern North America." Nature, 320, (6061), 441-444. London, England: Macmillan 
Journals. TIC: 225766. 
Stock, J.M.; Healy, J.H.; Hickman, S.H.; and Zoback, M.D. 1985. "Hydraulic Fracturing Stress 
Measurements at Yucca Mountain, Nevada, and Relationship to the Regional Stress Field." 
Journal of Geophysical Research, 90, (B10), 8691-8706. Washington, D.C.: American 
Geophysical Union. TIC: 219009. 
Stuckless, J.S.; Whelan, J.F.; and Steinkampf, W.C. 1991. "Isotopic Discontinuities in Ground 
Water Beneath Yucca Mountain, Nevada." High Level Radioactive Waste Management, 
Proceedings of the Second Annual International Conference, Las Vegas, Nevada, April 28-May 
3, 1991. 2, 1410-1415. La Grange Park, Illinois: American Nuclear Society. TIC: 204272. 
Thomas, J.M. 1996. Geochemical and Isotopic Interpretation of Groundwater Flow, 
Geochemical Processes, and Age Dating of Groundwater in the Carbonate-Rock Aquifers of the 
Southern Basin and Range. Ph.D. dissertation. Reno, Nevada: University of Nevada, Reno. TIC: 
247758.

ANL-NBS-HS-000021, REV 00 124 of 131 August 2000 
Thomas, J.M.; Welch, A.H.; and Dettinger, M.D. 1996. Geochemistry and Isotope Hydrology of 
Representative Aquifers in the Great Basin Region of Nevada, Utah, and Adjacent States. 
Professional Paper 1409-C. Denver, Colorado: U.S. Geological Survey. TIC: 235070. 
Thordarson, W. 1983. Geohydrologic Data and Test Results from Well J-13, Nevada Test Site, 
Nye County, Nevada. Water-Resources Investigations Report 83-4171. Denver, Colorado: U.S. 
Geological Survey. ACC: NNA.19870518.0071. 
Tucci, P. and Burkhardt, D.J. 1995. Potentiometric-Surface Map, 1993, Yucca Mountain and 
Vicinity, Nevada. Water-Resources Investigations Report 95-4149. Denver, Colorado: U.S. 
Geological Survey. ACC: MOL.19960924.0517. 
USGS (U.S. Geological Survey) 2000. Water-Level Data Analysis for the Saturated Zone Site- 
Scale Flow and Transport Model. ANL-NBS-HS-000034 REV 00. Denver, Colorado: U.S. 
Geological Survey. Submit to RPC URN-0281 
USGS (U.S. Geological Survey) n.d. Laboratory Analytical Sheets and Water Quality Data for 
USW H-6, Station ID: 3650491162855. Denver, Colorado: U.S. Geological Survey. ACC: 
NNA.19940323.0240. 
Waddell, R.K. 1982. Two-Dimensional, Steady-State Model of Ground-Water Flow, Nevada Test 
Site and Vicinity, Nevada-California. Water-Resources Investigations Report 82-4085. Denver, 
Colorado: U.S. Geological Survey. ACC: NNA.19870518.0055. 
Wemheuer, R.F. 1999. "First Issue of FY00 NEPO QAP-2-0 Activity Evaluations." Interoffice 
correspondence from R.F. Wemheuer (CRWMS M&O) to R.A. Morgan, October 1, 1999, 
LV.NEPO.RTPS.TAG.10/99-155, with enclosures. ACC: MOL.19991028.0162. 
Whelan, J.F.; Moscati, R.J.; Allerton, S.B.M.; and Marshall, B.D. 1998. Applications of Isotope 
Geochemistry to the Reconstruction of Yucca Mountain, Nevada, PaleohydrologyStatus of 
Investigations: June 1996. Open-File Report 98-83. Denver, Colorado: U.S. Geological Survey. 
ACC: MOL.19981012.0740. 
White, A.F. and Chuma, N.J. 1987. "Carbon and Isotopic Mass Balance Models of Oasis Valley 
- Fortymile Canyon Groundwater Basin, Southern Nevada." Water Resources Research , 23, (4), 
571-582. Washington, D.C.: American Geophysical Union. TIC: 237579. 
Winograd, I.J. and Pearson, F.J., Jr. 1976. "Major Carbon 14 Anomaly in a Regional Carbonate 
Aquifer: Possible Evidence for Megascale Channeling, South Central Great Basin." Water 
Resources Research, 12, (6), 1125-1143. Washington, D.C.: American Geophysical Union. TIC: 
217731. 
Winograd, I.J. and Thordarson, W. 1975. Hydrogeologic and Hydrochemical Framework, South- 
Central Great Basin, Nevada-California, with Special Reference to the Nevada Test Site. 
Professional Paper 712-C. Washington, D.C.: U.S. Geological Survey. TIC: 206787.

ANL-NBS-HS-000021, REV 00 125 of 131 August 2000 
Winograd, I.J.; Coplen, T.B.; Landwehr, J.M.; Riggs, A.C.; Ludwig, K.R.; Szabo, B.J.; Kolesar, 
P.T.; and Revesz, K.M. 1992. "Continuous 500,000-Year Climate Record from Vein Calcite in 
Devils Hole, Nevada." Science, 258, 255-260. Washington, D.C.: American Association for the 
Advancement of Science. TIC: 237563. 
Yang, I.C. and Peterman, Z.E. 1999. "Chemistry and Isotopic Content of Perched Water." In 
Hydrogeology of the Unsaturated Zone, North Ramp Area of the Exploratory Studies Facility, 
Yucca Mountain, Nevada. Rousseau, J.P.; Kwicklis, E.M.; and Gillies, D.C., eds. Water- 
Resources Investigations Report 98-4050. Denver, Colorado: U.S. Geological Survey. ACC: 
MOL.19990419.0335. 
Yang, I.C.; Rattray, G.W.; and Yu, P. 1996. Interpretation of Chemical and Isotopic Data from 
Boreholes in the Unsaturated Zone at Yucca Mountain, Nevada. Water-Resources Investigations 
Report 96-4058. Denver, Colorado: U.S. Geological Survey. ACC: MOL.19980528.0216. 
Yang, I.C.; Yu, P.; Rattray, G.W.; Ferarese, J.S.; and Ryan, J.N. 1998. Hydrochemical 
Investigations in Characterizing the Unsaturated Zone at Yucca Mountain, Nevada. Water- 
Resources Investigations Report 98-4132. Denver, Colorado: U.S. Geological Survey. ACC: 
MOL.19981012.0790. 
8.2 CODES, STANDARDS, REGULATIONS, AND PROCEDURES 
AP-3.10Q, Rev.2, ICN 2. Analysis and Models. Washington, D.C.: U.S. Department of Energy, 
Office of Civilian Radioactive Waste Management. ACC: MOL.20000619.0576. 
AP-3.15Q, Rev. 1, ICN 2. Managing Technical Product Inputs. Washington, D.C.: U.S. 
Department of Energy, Office of Civilian Radioactive Waste Management. ACC: 
MOL.20000713.0363. 
AP-SI.1Q, Rev. 2, ICN 4. Software Management. Washington, D.C.: U.S. Department of 
Energy, Office of Civilian Radioactive Waste Management. ACC: MOL.20000223.0508. 
AP-SIII.2Q, Rev. 0, ICN 2. Qualification of Unqualified Data and the Documentation of 
Rationale for Accepted Data. Washington, D.C.: U.S. Department of Energy, Office of Civilian 
Radioactive Waste Management. ACC: MOL.19991214.0625. 
AP-SV.1Q, Rev. 0, ICN 1. Control of the Electronic Management of Data. Washington, D.C.: 
U.S. Department of Energy, Office of Civilian Radioactive Waste Management. 
MOL.20000512.0068. 
QAP-2-0, Rev. 5. Conduct of Activities. Las Vegas, Nevada: CRWMS M&O. ACC: 
MOL.19980826.0209. 
QAP-2-3, Rev. 10. Classification of Permanent Items. Las Vegas, Nevada: CRWMS M&O. 
ACC: TBD.

ANL-NBS-HS-000021, REV 00 126 of 131 August 2000 
8.3 SOFTWARE 
Los Alamos National Laboratory 1994. Software Code: NETPATH. V2.13. 10303-2.13-00. 
URN-0371. 
8.4 SOURCE DATA, LISTED BY DATA TRACKING NUMBER 
GS000700012847.001. Chemical and Isotopic Data from Cind-R-Lite Well Samples Collected 
on 5/17/95 and 9/6/95. Submittal date: 07/10/2000. 
GS920408312321.002. Flowmeter (Tracejector) Survey on Test Wells in Permeable Zones in 
Yucca Mountain Area. Submittal date: 04/27/1987. 
GS920508312321.004. Chemical Analyses of Water from Selected Wells and Springs in the 
Yucca Mountain Area, Nevada and Southeastern California. Submittal date: 05/28/1992. 
GS930108315213.002. Water Chemistry and Sample Documentation for Two Samples from 
Lathrop Wells Cone and USW VH-2. Submittal date: 01/15/1993. 
GS930108315213.004. Uranium Isotopic Analyses of Groundwaters from SW Nevada  SE 
California. Submittal date: 01/21/1993. 
GS930308312323.001. Chemical Composition of Groundwater and the Locations of Permeable 
Zones in the Yucca Mountain Area. Submittal date: 03/05/1993. 
GS930908312323.003. Hydrochemical Data from Field Test and Lab Analyses of Water 
Samples Collected at Field Stations: USW VH-1, JF3, UE-29 UZN#91, Virgin Spring, Nevares 
Spring, UE-25 J#12, UE-25 J#13, UE-22 ARMY#1, and USW UZ-14. Submittal date: 
09/30/1993. 
GS950708315131.003. Woodrat Midden Age Data in Radiocarbon Years Before Present. 
Submittal date: 07/21/1995. 
GS950808312322.001. Field, Chemical, and Isotopic Data Describing Water Samples Collected 
in Death Valley National Monument and at Various Boreholes in and Around Yucca Mountain, 
Nevada, Between 1992 and 1995. Submittal date: 08/16/1995. 
GS951208312272.002. Tritium Analyses of Porewater from USW UZ-14. Submittal date: 
00/00/0000. URN-0527 
GS960208315215.001. Uranium and Thorium Isotope Data Determined by Mass Spectrometry 
for Dating Sub-Surface Secondary Deposits from ESF and Drill Hole Locations. Submittal date: 
02/21/1996. 
GS960308315131.001. Woodrat Midden Radiocarbon (C14) . Submittal date: 03/07/1996.

ANL-NBS-HS-000021, REV 00 127 of 131 August 2000 
GS960908315215.013. Uranium and Thorium Isotope Data for Waters Collected Between 
January 1994 and September 1996. Submittal date: 09/25/1996. 
GS960908315215.014. Uranium and Thorium Isotope Data for ESF Secondary Minerals 
Collected Between March 1996 and July 1996. Submittal date: 09/25/1996. 
GS970208315215.001. Uranium and Thorium Isotope Data Collected Between September 1996 
and February 1997 from Secondary Minerals in the ESF. Submittal date: 03/06/1997. 
GS970208315215.002. Uranium-Lead Isotope Data for ESF Secondary Minerals from Sep. 96 to 
Feb. 97. Submittal date: 03/06/1997. 
GS970708312323.001. Delta 18-O and Delta D Stable Isotope Analyses of a Bore-Hole Waters 
from GEXA Well 4 and VH-2. Submittal date: 07/22/1997. 
GS970808315215.012. Uranium and Thorium Isotope Data from Secondary Minerals in the ESF 
Collected Between 02/15/97 and 09/15/97. Submittal date: 09/17/1997. 
GS980108312322.003. Uranium Isotopic Data for Saturated- and Unsaturated-Zone Waters 
Collected Between December 1996 and December 1997. Submittal date: 01/29/1998. 
GS980108312322.005. Water Chemistry Data from Samples Collected at Borehole USW WT- 
24, Between 10/06/97 and 12/10/97. Submittal date: 01/26/1998. 
GS980208312322.006. Uranium Isotopic Data for Saturated- and Unsaturated-Zone Waters 
Collected by Non-YMP Personnel Between May 1989 and August 1997. Submittal date: 
02/03/1998. 
GS980908312322.008. Field, Chemical, and Isotopic Data from Precipitation Sample Collected 
Behind Service Station in Area 25 and Ground Water Samples Collected at Boreholes UE-25 C 
#2, UE-25 C #3, USW UZ-14, UE-25 WT #3, UE-25 WT #17, and USW WT-24, 10/06/97 to 
07/01/98. Submittal date: 09/15/1998. 
GS980908312322.009. Uranium Concentrations and 234U/238U Ratios from Spring, Well, 
Runoff, and Rain Waters Collected from the Nevada Test Site and Death Valley Vicinities and 
Analyzed Between 01/15/1998 and 08/15/1998. Submittal date: 09/23/1998. 
GS991208314221.001. Geologic Map of the Yucca Mountain Region. Submittal date: 
12/01/1999. 
GS991299992271.001. Preliminary Unsaturated Zone Borehole Hydrochemistry Data. Submittal 
date: 12/23/1999. 
GS991299995215.001. Preliminary Hydrochemical Data from Yucca Mountain. Submittal date: 
12/29/1999.

ANL-NBS-HS-000021, REV 00 128 of 131 August 2000 
LA0002JF831222.001. Apparent Infiltration Rates in Alluvium from USW UZ-N37, USW UZN54, 
USW UZ-14 and UE-25 UZ#16, Calculated by Chloride Mass Balance Method. Submittal 
date: 02/25/2000. 
LA0002JF831222.002. Apparent Infiltration Rates in PTN Units from USW UZ-7A, USW UZN55, 
USW UZ-14, UE-25 UZ#16, USW NRG-6, USW NRG-7A, and USW SD-6, SD-7, SD-9 
and SD-12 Calculated by the Chloride Mass Balance Method. Submittal date: 02/25/2000. 
LA9909JF831222.010. Chloride, Bromide, Sulfate, and Chlorine-36 Analyses of ESF 
Porewaters. Submittal date: 09/29/1999. 
LA9909JF831222.012. Chloride, Bromide, and Sulfate Analyses of Porewater Extracted from 
ESF Niche 3566 (Niche #1) and ESF 3650 (Niche #2) Drillcore. Submittal date: 09/29/1999. 
LAIT831341AQ96.001. Radionuclide Retardation, Measurements of Batch Sorption Distribution 
Coefficients for Barium, Cesium, Selenium, Strontium, Uranium, Plutonium, and Neptunium. 
Submittal date: 11/12/1996. 
LAJF831222AQ97.002. Chlorine-36 Analyses of Packrat Urine. Submittal date: 09/26/1997. 
LAJF831222AQ98.011. Chloride, Bromide, Sulfate and Chlorine-36 Analyses of Springs, 
Groundwater, Porewater, Perched Water and Surface Runoff. Submittal date: 09/10/1998. 
MO0007GNDWTRIS.002. Isotopic Content of Groundwater from Yucca Mountain Project 
Borehole, USW G-2, Extracted from ANL-NBS-HS-000021, Geochemical and Isotopic 
Constraints on Groundwater Flow Directions, Mixing and Recharge at Yucca Mountain, Nevada. 
Submittal date: 07/27/2000. Submit to RPC URN-0496 
MO0007GNDWTRIS.003. Isotopic Content of Groundwater from Yucca Mountain Project 
Boreholes UZ-14, WT-17, and WT #3, Extracted from ANL-NBS-HS-000021, Geochemical and 
Isotopic Constraints on Groundwater Flow Directions, Mixing and Recharge at Yucca Mountain, 
Nevada. Submittal date: 07/27/2000. Submit to RPC URN-0497 
MO0007GNDWTRIS.004. Isotopic Content of Groundwater from Borehole TW-5, Extracted 
from ANL-NBS-HS-000021, Geochemical and Isotopic Constraints on Groundwater Flow 
Directions, Mixing and Recharge at Yucca Mountain, Nevada. Submittal date: 07/27/2000. 
Submit to RPC URN-0498 
MO0007GNDWTRIS.005. Isotopic Content of Groundwater from Yucca Mountain Project 
Borehole JF #3, Extracted from ANL-NBS-HS-000021, Geochemical and Isotopic Constraints 
on Groundwater Flow Directions, Mixing and Recharge at Yucca Mountain, Nevada. Submittal 
date: 07/28/2000. Submit to RPC URN-0499 
MO0007GNDWTRIS.006. Isotopic Content of Groundwater from Selected Yucca Mountain 
Project WT Boreholes, Extracted from ANL-NBS-HS-000021, Geochemical and Isotopic

ANL-NBS-HS-000021, REV 00 129 of 131 August 2000 
Constraints on Groundwater Flow Directions, Mixing and Recharge at Yucca Mountain, Nevada. 
Submittal date: 07/28/2000. Submit to RPC URN-0500 
MO0007GNDWTRIS.007. Isotopic Content of Groundwater from Yucca Mountain Project 
Boreholes WT #14, WT #15, and WT #12, Extracted from ANL-NBS-HS-000021, Geochemical 
and Isotopic Constraints on Groundwater Flow Directions, Mixing and Recharge at Yucca 
Mountain, Nevada. Submittal date: 07/28/2000. Submit to RPC URN-0501 
MO0007GNDWTRIS.008. Isotopic Content of Groundwater from Yucca Mountain Project 
Borehole UE-25 p#1 Extracted from ANL-NBS-HS-000021, Geochemical and Isotopic 
Constraints on Groundwater Flow Directions, Mixing and Recharge at Yucca Mountain, Nevada. 
Submittal date: 07/28/2000. Submit to RPC URN-0502 
MO0007GNDWTRIS.009. Isotopic Content of Groundwater from Selected Yucca Mountain 
Project Boreholes Extracted from ANL-NBS-HS-000021, Geochemical and Isotopic Constraints 
on Groundwater Flow Directions, Mixing and Recharge at Yucca Mountain, Nevada. Submittal 
date: 07/28/2000. Submit to RPC URN-0503 
MO0007GNDWTRIS.010. Isotopic Content of Groundwater from Selected Yucca Mountain 
Project Boreholes Extracted from ANL-NBS-HS-000021, Geoochemical and Isotopic 
Constraints on Groundwater Flow Directions, Mixing and Recharge at Yucca Mountain, Nevada. 
Submittal date: 07/28/2000. Submit to RPC URN-0516 
MO0007GNDWTRIS.011. Isotopic Content of Groundwater from Selected Boreholes Not 
Drilled for the Yucca Mountain Project Extracted from ANL-NBS-HS-000021, Geochemical 
and Isotopic Constraints on Groundwater Flow Directions, Mixing and Recharge at Yucca 
Mountain, Nevada. Submittal date: 07/28/2000. Submit to RPC URN-0517 
MO0007GNDWTRIS.012. Isotopic Content of Groundwater from NC-EWDP Boreholes, 
Extracted from ANL-NBS-HS-000021, Geochemical and Isotopic Constraints on Groundwater 
Flow Directions, Mixing and Recharge at Yucca Mountain, Nevada. Submittal date: 07/28/2000. 
Submit to RPC URN-0504 
MO0007GNDWTRIS.013. Isotopic Content of Perched Groundwater from Yucca Mountain 
Project Boreholes Extracted from ANL-NBS-HS-000021, Geochemical and Isotopic Constraints 
on Groundwater Flow Directions, Mixing and Recharge at Yucca Mountain, Nevada. Submittal 
date: 07/28/2000. Submit to RPC URN-0505 
MO0007MAJIONPH.002. Major Ion Content of Groundwater from Borehole TW-5 Extracted 
from ANL-NBS-HS-000021, Geochemical and Isotopic Constraints on Groundwater Flow 
Directions, Mixing and Recharge at Yucca Mountain, Nevada. Submittal date: 07/27/2000. 
Submit to RPC URN-0506 
MO0007MAJIONPH.003. Major Ion Content of Groundwater from Yucca Mountain Project 
Borehole USW G-2, Extracted from ANL-NBS-HS-000021, Geochemical and Isotopic

ANL-NBS-HS-000021, REV 00 130 of 131 August 2000 
Constraints on Groundwater Flow Directions, Mixing and Recharge at Yucca Mountain, Nevada. 
Submittal date: 07/27/2000. Submit to RPC URN-0507 
MO0007MAJIONPH.004. Major Ion Content of Groundwater from Borehole ONC #1, 
Extracted from ANL-NBS-HS-000021, Geochemical and Isotopic Constraints on Groundwater 
Flow Directions, Mixing and Recharge at Yucca Mountain, Nevada. Submittal date: 07/27/2000. 
Submit to RPC URN-0508 
MO0007MAJIONPH.005. Major Ion Content of Groundwater from Boreholes UZ-14, WT-17, 
and WT #3, Extracted from ANL-NBS-HS-000021, Geoochemical and Isotopic Constraints on 
Groundwater Flow Directions, Mixing and Recharge at Yucca Mountain, Nevada. Submittal 
date: 07/27/2000. Submit to RPC URN-0509 
MO0007MAJIONPH.006. Major Ion Content of Groundwater from Selected Boreholes Not 
Drilled on the Yucca Mountain Project, Extracted from ANL-NBS-HS-000021, Geochemical 
and Isotopic Constraints on Groundwater Flow Directions, Mixing and Recharge at Yucca 
Mountain, Nevada. Submittal date: 07/25/2000. Submit to RPC URN-0510 
MO0007MAJIONPH.007. Major Ion Content of Groundwater from Yucca Mountain Project 
Borehole UE-25 UZ #16, Extracted from ANL-NBS-HS-000021, Geochemical and Isotopic 
Constraints on Groundwater Flow Directions, Mixing and Recharge at Yucca Mountain, Nevada. 
Submittal date: 07/27/2000. Submit to RPC URN-0511 
MO0007MAJIONPH.008. Major Ion Content of Groundwater from Selected YMP and Other 
Boreholes Extracted from ANL-NBS-HS-000021, Geochemical and Isotopic Constraints on 
Groundwater Flow Directions, Mixing and Recharge at Yucca Mountain, Nevada. Submittal 
date: 07/27/2000. Submit to RPC URN-0512 
MO0007MAJIONPH.009. Major Ion Content of Groundwater from Borehole NDOT Extracted 
from ANL-NBS-HS-000021, Geochemical and Isotopic Constraints on Groundwater Flow 
Directions, Mixing and Recharge at Yucca Mountain, Nevada. Submittal date: 07/27/2000. 
Submit to RPC URN-0518 
MO0007MAJIONPH.010. Major Ion Content of Groundwater from Borehole UE-25 p #1 
Extracted from ANL-NBS-HS-000021, Geochemical and Isotopic Constraints on Groundwater 
Flow Directions, Mixing and Recharge at Yucca Mountain, Nevada. Submittal date: 07/27/2000. 
Submit to RPC URN-0519 
MO0007MAJIONPH.011. Major Ion Content of Groundwater from Selected Yucca Mountain 
Project Boreholes Extracted from ANL-NBS-HS-000021, Geochemical and Isotopic Constraints 
on Groundwater Flow Directions, Mixing and Recharge at Yucca Mountain, Nevada. Submittal 
date: 07/27/2000. Submit to RPC URN-0520 
MO0007MAJIONPH.012. Major Ion Content of Groundwater from Selected YMP and Other 
Boreholes Extracted from ANL-NBS-HS-000021, Geochemical and Isotopic Constraints on

ANL-NBS-HS-000021, REV 00 131 of 131 August 2000 
Groundwater Flow Directions, Mixing and Recharge at Yucca Mountain, Nevada. Submittal 
date: 07/27/2000. Submit to RPC URN-0521 
MO0007MAJIONPH.013. Major Ion Content of Groundwater from Selected YMP and Other 
Boreholes Extracted from ANL-NBS-HS-000021, Geoochemical and Isotopic Constraints on 
Groundwater Flow Directions, Mixing and Recharge at Yucca Mountain, Nevada. Submittal 
date: 07/27/2000. Submit to RPC URN-0522 
MO0007MAJIONPH.014. Major Ion Content of Groundwater from Selected Boreholes Not 
Drilled on the Yucca Mountain Project Extracted from ANL-NBS-HS-000021, Geochemical and 
Isotopic Constraints on Groundwater Flow Directions, Mixing and Recharge at Yucca Mountain, 
Nevada. Submittal date: 07/27/2000. Submit to RPC URN-0523 
MO0007MAJIONPH.015. Major Ion Content of Groundwater from NC-EWDP Boreholes 
Extracted from ANL-NBS-HS-000021, Geochemical and Isotopic Constraints on Groundwater 
Flow Directions, Mixing and Recharge at Yucca Mountain, Nevada. Submittal date: 07/27/2000. 
Submit to RPC URN-0524 
MO0007MAJIONPH.016. Major Ion Content of Perched Groundwater from Selected YMP 
Boreholes with Perched Water Extracted from ANL-NBS-HS-000021, Geochemical and Isotopic 
Constraints on Groundwater Flow Directions, Mixing and Recharge at Yucca Mountain, Nevada. 
Submittal date: 07/28/2000. Submit to RPC URN-0525 
MO0008MAJIONPH.017. Major Ion Content of Groundwater from Selected WT Boreholes 
Drilled for the Yucca Mountain Project, Extracted from ANL-NBS-HS-000021, Geochemical 
and Isotopic Constraints on Major Ion Concentrations and pH from Table 3 of AMR ANL-NBSHS-
000021. Submittal date: 08/01/2000. Submit to RPC URN-0526 
MO9907YMP99025.001. YMP-99-025.01, List of Boreholes. Submittal date: 7/19/1999. 
8.5 OUTPUT DATA, LISTED BY DATA TRACKING NUMBER 
LA0006EK12213S.001. NETPATH Model Results for Yucca Mountain Groundwater Carbon- 
14 Age Corrections. Submittal date: 06/05/2000.